JP2005098278A - Exhaust gas recirculating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust gas recirculation device easy to perform high temperature control of exhaust gas in an exhaust gas recirculation passage 4 and capable of preventing sticking of a first valve element body 61 in an EGR gas cooler 14 side of an exhaust gas flow rate ratio regulation valve 18 due to deposit of sticky material. <P>SOLUTION: Only the first valve element 61 in the EGR gas cooler 14 side of a double poppet type valve 53 of the exhaust gas flow rate ratio regulation valve 18 is opened during engine stop. Consequently, sticking of the first valve element 61 in the EGR gas cooler 14 side of the exhaust gas flow rate ratio regulation valve 18 due to deposit od sticky material is prevented. A double poppet type valve 53 of the exhaust gas flow rate ratio regulation valve 18 is arranged in vicinity of a downstream side of an exhaust gas cooling device composed of the EGR gas cooler 14 and a bypass piping 15 or the like. Consequently, high temperature control of exhaust gas flowing in the exhaust gas recirculation passage toward an inside of the intake passage 3 is easy to be performed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an exhaust gas recirculation device having an exhaust gas recirculation passage for recirculating a part of exhaust gas of an internal combustion engine from an exhaust passage to an intake passage. The present invention relates to an exhaust gas recirculation device equipped with an exhaust heat exchanger and a bypass pipe that bypasses the exhaust heat exchanger.

[Conventional technology]
Conventionally, in an exhaust gas recirculation device having an exhaust gas recirculation pipe for recirculating a part of exhaust gas of an internal combustion engine from an exhaust passage to an intake passage, the internal combustion engine is recirculated when the exhaust gas is recirculated to the intake side. The exhaust gas recirculation amount control valve for adjusting the flow rate (exhaust gas recirculation amount: EGR amount) of the exhaust gas recirculated (recirculated) to the intake side is exhaust gas. It is provided at the inlet part of the reflux pipe or in the middle or at the outlet part. Further, in an exhaust gas recirculation device provided with an exhaust gas recirculation pipe (EGR pipe) for recirculating a part of the exhaust gas of the internal combustion engine from the exhaust passage to the intake passage, the exhaust gas recirculated to the intake passage of the internal combustion engine. When the gas is cooled in the middle of the EGR pipe, the temperature of the exhaust gas is lowered and the volume is reduced, so that the combustion temperature of the fuel in the internal combustion engine is lowered without lowering the output of the internal combustion engine. Since it is possible to reduce the generation of nitrogen oxides (NOx), there are some equipped with a water-cooled EGR gas cooler in the middle of an EGR pipe for recirculating exhaust gas to an internal combustion engine. However, if an EGR gas cooler is provided in the middle of the EGR pipe, the exhaust gas to be recirculated to the internal combustion engine is always cooled, so that the warming effect on the intake air is small even if the exhaust gas is recirculated during cold weather. That is, in general, recirculation of exhaust gas having a high temperature to the intake side during cold weather can obtain a warming effect on the intake air, but the exhaust gas cooled by the EGR gas cooler during cold weather is brought to the intake side. Since the recirculation is performed, a sufficient warming effect cannot be obtained, and the ignitability in the internal combustion engine may be reduced during cold weather, and white smoke may be generated.

  Therefore, for the purpose of optimizing the temperature of the exhaust gas in accordance with the operating state of the internal combustion engine, exhaust for recirculating a part of the exhaust gas of the internal combustion engine (exhaust gas recirculation gas: EGR gas) from the exhaust passage to the intake passage. A cooling passage provided with an exhaust heat exchanger (EGR gas cooler) that cools EGR gas using engine cooling water and a bypass passage that bypasses the cooling passage are provided in the middle of the gas recirculation passage (EGR passage). An exhaust gas flow rate adjusting valve (3-way valve) for adjusting the EGR gas flow rate ratio of the cooling passage and the bypass passage is provided downstream of the EGR gas cooler, and the exhaust gas for adjusting the total EGR amount in the vicinity of the outlet of the EGR passage An exhaust gas recirculation device (EGR device) provided with a recirculation amount control valve (flow rate control valve) has been proposed (see, for example, Patent Document 1). This EGR device includes an exhaust side exhaust gas recirculation pipe, a bypass pipe from the branching part to the merging part, an exhaust side exhaust gas recirculation pipe from the branching part to the EGR gas cooler, and an intake side exhaust gas recirculation pipe from the EGR gas cooler to the merging part. In addition, the merging portion and the intake pipe are connected by an intake side exhaust gas recirculation pipe. The engine coolant is configured to circulate between the engine and the EGR gas cooler through a pair of coolant pipes.

[Conventional technical problems]
However, in the EGR device described in Patent Document 1, a three-way valve, an EGR gas cooler, a bypass pipe, and a flow rate control valve are each configured as a single unit. Thereby, since it couple | bonds using the exhaust gas recirculation | reflux pipe | tube which introduce | transduces EGR gas into each single-piece | unit, the channel length of the whole EGR channel | path becomes very long. In particular, a response delay occurs when adjusting the flow rate ratio of the EGR gas between the cooling passage and the bypass passage, and it is difficult to perform advanced temperature control. In addition, since the outside air hits the exhaust gas recirculation pipes connecting the single units, the EGR gas temperature obtained by adjusting the flow rate ratio of the EGR gas in the cooling passage and the bypass passage is likely to fluctuate. hard. As a result, it becomes impossible to mix the EGR gas controlled to the optimum temperature corresponding to the operating state of the internal combustion engine into the intake air, so that there is a problem in performance, particularly the NOx reduction effect in the exhaust gas is deteriorated. .

  In order to obtain a satisfactory NOx reduction effect in the exhaust gas, and to protect the internal components of the three-way valve and the flow control valve from heat, the EGR gas cooler It is necessary to introduce engine cooling water not only to the three-way valve and the flow rate control valve. In this case, a cooling water pipe for circulating engine cooling water to the EGR gas cooler, the three-way valve and the flow rate adjustment valve is required between the engine and the engine, and the cooling water passage of the EGR gas cooler is connected to the three-way valve. Due to the necessity of a cooling water pipe connecting the cooling water passage of the valve, a cooling water pipe connecting the cooling water passage of the EGR gas cooler and the cooling water passage of the flow rate control valve, etc. The number of parts of the entire required EGR gas cooling device increases, and the assembly becomes complicated, resulting in a problem that the mountability in the engine room of the vehicle is poor.

  A cooling passage provided with an exhaust heat exchanger (EGR gas cooler) that cools the EGR gas using engine cooling water in the middle of the EGR passage for returning the EGR gas from the exhaust passage to the intake passage, and a cooling passage A bypass passage is provided, and an exhaust gas flow rate adjustment valve for adjusting the EGR gas flow rate ratio between the cooling passage and the bypass passage is provided on the EGR gas cooler upstream side of the cooling passage and the inlet side of the bypass passage, There has also been proposed an exhaust gas recirculation device (EGR device) provided with an EGR control valve that adjusts the total EGR amount downstream of the junction between the outlet side and the outlet side of the bypass passage (see, for example, Patent Document 2). ).

  However, in the EGR device described in Patent Document 2, the exhaust gas flow rate control valve is installed on the upstream side of the EGR gas cooler that forms the cooling passage inside and the bypass pipe that forms the bypass passage inside. When the target value of the EGR gas temperature is changed and the EGR gas temperature is changed, the control responsiveness is deteriorated by the volume (length) of the EGR gas cooler and the bypass pipe, and it is difficult to control the EGR gas temperature. Therefore, it is conceivable to install an exhaust gas flow rate control valve on the downstream side of the EGR gas cooler that forms the cooling passage inside and the bypass pipe that forms the bypass passage inside.

However, the exhaust gas flow ratio control valve is provided in the EGR passage through which exhaust gas containing particulate matter such as combustion residue and carbon flows. In particular, the fine particles cooled after passing through the EGR gas cooler adhere to the valve body on the EGR gas cooler side of the exhaust gas flow ratio control valve, and deposit an adhesive (the lower temperature side has higher adhesiveness than the high temperature side). Form. Then, after the engine is stopped, the EGR gas cooler side valve element of the exhaust gas flow ratio adjusting valve is seated on a valve seat (for example, a valve seat), and the EGR gas is introduced from the EGR gas cooler into the EGR passage on the intake passage side. Is closed, the adhesive deposit accumulates across the valve body and the valve seat on the EGR gas cooler side of the exhaust gas flow rate control valve, so that the valve on the EGR gas cooler side of the exhaust gas flow rate control valve Since the body adheres to the valve seat, there is a possibility that the valve body on the EGR gas cooler side of the exhaust gas flow rate adjustment valve may not be smoothly opened and closed by an actuator made of, for example, a diaphragm.
JP-A-11-280565 (page 1-6, FIG. 1) EP1030050A1 (page 1-7, FIGS. 1 to 3)

  An object of the present invention is to provide an exhaust gas recirculation device that can easily control the exhaust gas temperature in the exhaust gas recirculation path to a high degree. It is another object of the present invention to provide an exhaust gas recirculation device capable of preventing the exhaust gas flow ratio adjusting valve on the exhaust heat exchanger side from sticking due to an adhesive deposit. It is another object of the present invention to provide an exhaust gas recirculation device that can improve the mountability to a vehicle by reducing the length of the exhaust gas recirculation path or the cooling water circulation path. Furthermore, it is an object of the present invention to provide an exhaust gas recirculation device capable of effectively reducing the generation of nitric oxide without causing a decrease in the output of the internal combustion engine and a decrease in the operability of the internal combustion engine.

  According to the first aspect of the present invention, in the exhaust gas recirculation device provided with the exhaust gas recirculation path for recirculating a part of the exhaust gas of the internal combustion engine to the intake side, the exhaust gas flowing in the exhaust gas recirculation path The flow rate of the exhaust gas flowing in the exhaust heat exchanger in the vicinity of the downstream side of the water-cooled exhaust heat exchanger that cools the gas and the bypass pipe that bypasses the exhaust gas flowing in the exhaust gas recirculation path from the exhaust heat exchanger By providing an exhaust gas flow rate control valve that continuously or stepwise adjusts the ratio of the flow rate of the exhaust gas flowing through the bypass pipe, the exhaust gas flow rate control valve is connected to the exhaust heat exchanger through the first introduction hole. Thus, the low temperature exhaust gas introduced into the intake side and the high temperature exhaust gas introduced into the intake side from the bypass pipe through the second introduction hole can be mixed (mixed).

  In addition, by providing an exhaust gas flow ratio control valve in the vicinity of the downstream side of the water-cooled exhaust heat exchanger and bypass pipe, the exhaust heat exchanger and bypass pipe can be changed when the exhaust gas temperature in the exhaust gas recirculation path is changed. The control responsiveness of the exhaust gas flow rate control valve is improved by the volume (length). As a result, the exhaust gas temperature in the exhaust gas recirculation path is highly controlled so that the exhaust gas temperature in the exhaust gas recirculation path quickly converges to the target value without abnormally overshooting or undershooting the target value. It becomes easy to do.

  In addition, a first introduction hole for introducing exhaust gas from the exhaust heat exchanger, a second introduction hole for introducing exhaust gas from the bypass pipe, and two second openings in the vicinity of the downstream side of the water-cooled exhaust heat exchanger and bypass pipe 1. An exhaust gas flow ratio control valve having a valve for adjusting an opening area of at least the first introduction hole of the first and second introduction holes is provided, and the valve of the exhaust gas flow ratio control valve is opened when the operation of the internal combustion engine is stopped. By doing so, even if fine particles contained in the exhaust gas adhere to the exhaust heat exchanger side valve to form a sticky deposit, the exhaust gas flow rate control valve and the valve housing (for example, the valve Since no sticky deposit is deposited across the seat or valve seat), the valve of the exhaust gas flow rate control valve does not stick. Accordingly, for example, the valve of the exhaust gas flow rate control valve can be smoothly opened and closed by the actuator, so that the control response of the exhaust gas flow rate control valve can be improved.

  In addition, the exhaust gas recirculation pipe (pipe) that connects the exhaust heat exchanger and the exhaust gas flow ratio control valve, and the exhaust gas recirculation pipe (pipe) that connects the bypass pipe and the exhaust gas flow ratio control valve are extremely shortened. This makes it easy to handle the piping. Therefore, assembly becomes easy and the passage length of the exhaust gas recirculation path is shortened, so that the mountability to the vehicle can be improved. Further, since the total flow rate of the exhaust gas passing through the exhaust gas recirculation path can be optimized and recirculated to the intake side of the internal combustion engine, it is accompanied by a decrease in the output of the internal combustion engine and a decrease in the operability of the internal combustion engine. Therefore, the generation of nitric oxide can be effectively reduced. In addition, since the temperature of the exhaust gas passing through the exhaust gas recirculation path can be optimized and recirculated to the intake side of the internal combustion engine, a sufficient warming effect on the intake air can be obtained to improve the ignitability in the internal combustion engine. Can greatly improve.

  According to the second aspect of the present invention, when the second valve body on the bypass pipe side fully opens the second introduction hole for introducing the exhaust gas from the bypass pipe, The first valve body on the exchanger side has a structure in which a first introduction hole for introducing exhaust gas from the exhaust heat exchanger is opened by a predetermined opening or more. That is, even when high-temperature exhaust gas is introduced from the bypass pipe through the second introduction hole, the first introduction hole is not fully closed so that the exhaust heat exchanger introduces the first introduction hole through the first introduction hole. The internal components of the exhaust gas flow rate control valve can be cooled by the low temperature exhaust gas. Therefore, since the internal components of the exhaust gas flow rate control valve can be protected from the heat of the high temperature exhaust gas, the control response of the exhaust gas flow rate control valve can be improved.

  In addition, a normally open type (normally open type) valve is used as the first valve body on the exhaust heat exchanger side, and a normally closed type (normally closed type) valve is used as the second valve body on the bypass piping side. Thus, even when the actuator of the exhaust gas flow rate control valve cannot be controlled, the low-temperature exhaust gas cooled by passing through the exhaust heat exchanger flows into the exhaust gas flow rate control valve. As a result, even if the actuator of the exhaust gas flow ratio control valve fails, the internal components of the exhaust gas flow ratio control valve can be protected from the heat of the hot exhaust gas, preventing secondary failure of the exhaust gas recirculation device. it can.

  According to the invention described in claim 3, the exhaust gas flow rate control valve is configured such that the first valve body on the exhaust heat exchanger side opens when the operation of the internal combustion engine is stopped, and the bypass pipe side Since the second valve body is configured to close, fine particles contained in the exhaust gas adhere to the first valve body on the exhaust heat exchanger side of the exhaust gas flow rate control valve, and an adhesive deposit is formed. Even if formed, an adhesive deposit does not accumulate across the first valve body on the exhaust heat exchanger side of the exhaust gas flow ratio control valve and the valve housing (for example, a valve seat or a valve seat). The exhaust gas flow rate control valve does not stick. Accordingly, for example, the valve of the exhaust gas flow rate control valve can be smoothly opened and closed by the actuator, so that the control response of the exhaust gas flow rate control valve can be improved.

  According to invention of Claim 4, as a valve | bulb, the substantially circular 1st bowl-shaped part which comprises a 1st valve body, the substantially circular 2nd bowl-shaped part which comprises a 2nd valve body, and a 1st bowl-shaped The first valve body and the second valve body are reciprocated by separate shaft-like parts by being constituted by a double poppet type valve comprising a shaft-like part that reciprocates integrally with the first and second hook-like parts. Compared to the above, the number of parts and the number of assembling steps can be reduced, and the cost can be reduced. According to the fifth aspect of the present invention, the first valve body and the second valve body can be operated by one actuator and one valve body urging means. Compared with the case where the body is operated by separate actuators and separate valve body urging means, the number of parts and assembly man-hours can be reduced, and the cost can be reduced.

  According to the sixth aspect of the present invention, the exhaust gas flow rate control valve is exhausted from the first introduction hole for introducing the exhaust gas from the first exhaust gas passage of the exhaust heat exchanger and from the second exhaust gas passage of the bypass pipe. A second introduction hole for introducing gas, a normally open first valve body for adjusting an opening area of the first introduction hole, a normally closed second valve body for adjusting an opening area of the second introduction hole, and an inside thereof By configuring the mixture chamber for mixing the high temperature exhaust gas and the low temperature exhaust gas, in the exhaust gas flow rate control valve, the mixture is introduced from the first exhaust gas passage of the exhaust heat exchanger through the first introduction hole. It is possible to mix (mix) the low-temperature exhaust gas introduced into the room and the high-temperature exhaust gas introduced from the second exhaust gas passage of the bypass pipe into the mixture chamber through the second introduction hole.

  According to the invention of claim 7, the exhaust gas recirculation amount control valve communicates with the exhaust heat exchanger via the first introduction hole and communicates with the bypass pipe via the second introduction hole, An exhaust heat exchanger is constituted by a valve body that adjusts the opening area of the communication passage, an actuator that drives the valve body in a valve opening direction, and a valve body biasing means that biases the valve body in a valve closing direction. Since the exhaust gas cooled inside the exhaust gas flows into the communication passage of the exhaust gas recirculation amount control valve, the internal components of the exhaust gas recirculation amount control valve can be protected. The control responsiveness can be improved.

  According to the invention described in claim 8, the exhaust heat exchanger and the bypass pipe are arranged in parallel in the middle of the exhaust gas recirculation path for recirculating a part of the exhaust gas of the internal combustion engine to the intake side. By arranging the exhaust gas cooling device in the vicinity, the size of the exhaust gas cooling device can be reduced as compared with the prior art in which the exhaust heat exchanger and the bypass pipe are provided apart from each other. Therefore, the piping can be easily handled and the exhaust gas cooling device can be easily assembled, so that the mounting property on the vehicle can be improved.

  According to the ninth aspect of the present invention, the bypass pipe has a dimension that is substantially the same as the dimension of the exhaust heat exchanger in the cylinder direction, and is arranged in parallel to and in the vicinity of the exhaust heat exchanger. And by providing the bypass pipe with a bellows-like bellows part that can be expanded and contracted in the cylinder direction of the bypass pipe, the high-temperature exhaust gas is cooled with cooling water and the exhaust heat exchanger becomes a low-temperature part, The bellows part can absorb the difference in thermal expansion from the bypass pipe that becomes the high temperature part by passing the exhaust gas as it is. Thereby, it becomes an exhaust-gas cooling device excellent in durability.

  According to the invention described in claim 10, in the middle of the exhaust gas recirculation path for recirculating a part of the exhaust gas of the internal combustion engine to the intake side, the exhaust heat exchanger, the bypass pipe, and the exhaust gas flow rate control valve Are connected and integrated in series to provide an exhaust gas recirculation pipe (pipe) that connects the exhaust heat exchanger and the exhaust gas flow rate control valve, and a bypass pipe and an exhaust gas flow rate control valve. Since an exhaust gas recirculation pipe (pipe) to be coupled is not necessary, the number of parts can be reduced. Therefore, the assembling property between the exhaust heat exchanger and the exhaust gas flow rate control valve can be improved, or the assembling property between the bypass pipe and the exhaust gas flow rate control valve can be improved, and the exhaust gas recirculation can be improved. Since the passage length of the road can be greatly shortened, the piping can be easily routed and the mounting property to the vehicle can be further improved. Further, in the middle of the exhaust gas recirculation path, the exhaust heat exchanger and the exhaust gas flow rate control valve are directly connected and integrated in series, so that the heat of the exhaust gas cooled by the exhaust heat exchanger is exhausted. Since heat can be efficiently transferred to the gas flow rate control valve and the internal components of the exhaust gas flow rate control valve can be cooled, the internal components of the exhaust gas flow rate control valve can be protected from the heat of the exhaust gas. Therefore, the control responsiveness of the exhaust gas flow rate control valve can be improved.

  According to the eleventh aspect of the present invention, the exhaust gas flow rate control valve, the exhaust gas recirculation amount control valve, and the exhaust gas recirculation path for recirculating a part of the exhaust gas of the internal combustion engine to the intake side are provided. Are directly coupled and integrated in series, so that an exhaust gas recirculation pipe (pipe) for coupling the exhaust gas flow rate control valve and the exhaust gas recirculation amount control valve becomes unnecessary, and the number of parts can be reduced. Therefore, it is possible to improve the assembly of the exhaust gas flow rate control valve and the exhaust gas recirculation amount control valve, and the passage length of the exhaust gas recirculation path can be greatly shortened. Can be more easily mounted. Further, exhaust temperature variation between the exhaust gas flow rate control valve and the exhaust gas recirculation amount control valve can be suppressed, and the exhaust gas recirculation path length is shortened, so that the exhaust gas flow rate control valve In addition, the control response of the exhaust gas recirculation amount control valve can be improved.

  According to the twelfth aspect of the present invention, the internal components of the exhaust gas flow rate control valve and the internal components of the exhaust gas recirculation amount control valve are accommodated and held in a single housing, so that the exhaust gas flow rate is controlled. The ratio control valve and the exhaust gas recirculation amount control valve can be directly connected and integrated in series, and the exhaust gas flow ratio control valve and the exhaust gas recirculation amount control valve can share one housing.

  According to the invention described in claim 13, the exhaust heat exchange is performed in the middle of the cooling water circulation path for circulating the cooling water of the internal combustion engine in the order of the exhaust heat exchanger, the exhaust gas flow rate control valve, and the exhaust gas recirculation amount control valve. A cooling water pipe for connecting the exhaust heat exchanger and the exhaust gas flow rate control valve by directly connecting and integrating the exhaust gas, the exhaust gas flow rate control valve and the exhaust gas recirculation control valve in series, and Since the cooling water piping for connecting the exhaust gas flow rate control valve and the exhaust gas recirculation amount control valve is not required, the number of parts can be reduced. Therefore, the passage length of the cooling water circulation path can be greatly shortened, so that the cooling water pipe can be easily routed and the mountability to the vehicle can be improved. Then, by introducing cooling water directly from the exhaust heat exchanger to the exhaust gas flow rate control valve and the exhaust gas recirculation amount control valve, the exhaust gas passing through the exhaust gas flow rate control valve, the exhaust gas recirculation amount control valve The exhaust gas passing through the exhaust gas, the internal components of the exhaust gas flow rate control valve, and the internal components of the exhaust gas recirculation amount control valve can be cooled using cooling water.

  According to the fourteenth aspect of the present invention, the exhaust gas flow rate is controlled with respect to the exhaust gas recirculation path in the housing that houses and holds the internal component parts of the exhaust gas flow rate control valve and the internal component parts of the exhaust gas recirculation amount control valve. A cooling water passage constituting a part of the cooling water circulation path is formed on the internal component side of the ratio control valve and the internal component side of the exhaust gas recirculation amount control valve. The exhaust heat exchanger is disposed on the internal component side of the exhaust gas flow rate control valve and the internal component side of the exhaust gas recirculation amount control valve with respect to the bypass pipe. As a result, the internal components of the exhaust gas flow rate control valve and the internal components of the exhaust gas recirculation amount control valve are cooled by cooling the housing using the cooling water introduced directly from the exhaust heat exchanger into the cooling water passage. Can be cooled. Therefore, since the internal components of the exhaust gas flow rate control valve and the internal components of the exhaust gas recirculation control valve can be protected from the heat of the exhaust gas, the control responsiveness of the exhaust gas flow ratio control valve and the exhaust gas recirculation control valve Can be improved.

  According to the fifteenth aspect of the present invention, the exhaust gas flow rate is controlled with respect to the exhaust gas recirculation path in the housing that houses and holds the internal component parts of the exhaust gas flow rate control valve and the internal component parts of the exhaust gas recirculation amount control valve. A cooling water passage constituting a part of the cooling water circulation path is provided on the internal component side of the ratio control valve and the internal component side of the exhaust gas recirculation amount control valve. Then, by providing heat transfer fins in the cooling water passage of the housing, the heat of the housing heated to high temperature by the exhaust gas passing through the housing of the exhaust gas flow rate control valve and the exhaust gas recirculation amount control valve is cooled. The cooling water circulating in the water passage can be efficiently transmitted. As a result, the internal components of the exhaust gas flow rate control valve and the internal components of the exhaust gas recirculation amount control valve can be cooled using the cooling water. Therefore, since the internal components of the exhaust gas flow rate control valve and the internal components of the exhaust gas recirculation control valve can be protected from the heat of the exhaust gas, the control responsiveness of the exhaust gas flow ratio control valve and the exhaust gas recirculation control valve Can be improved.

  According to the sixteenth aspect of the present invention, the valve opening degree of the exhaust gas flow rate control valve and the exhaust gas temperature detected by the operating state detecting means or the exhaust gas temperature detected by the exhaust temperature gas detecting means are determined. By controlling the opening degree of the exhaust gas recirculation amount control valve continuously or stepwise, the temperature and total flow rate of the exhaust gas recirculated from the exhaust gas recirculation passage to the intake passage can be optimized. As a result, the temperature and total flow rate of the exhaust gas recirculated from the exhaust gas recirculation path to the intake passage can be optimized. For example, the exhaust gas is cooled by the exhaust heat exchanger at normal times and recirculated to the intake passage. As a result, the emission amount of nitrogen oxide (NOx) can be effectively reduced without lowering the output of the internal combustion engine and the operability of the internal combustion engine, and exhaust particulates (particulate matter) : PM) can also be reduced. In addition, since the exhaust gas can be recirculated to the intake passage while the temperature is high during cold weather, a sufficient warming effect on the intake air can be obtained, and the generation of white smoke during cold weather can be prevented.

  According to the invention described in claim 17, at the time of cold start, that is, when the temperature of the cooling water of the internal combustion engine is lower than the first predetermined value, the valve opening degree of the exhaust gas flow rate control valve is controlled, The second valve body is opened. As a result, the second introduction hole is opened, so that most of the exhaust gas flowing in the exhaust gas recirculation path bypasses the exhaust heat exchanger and passes through the bypass pipe. Therefore, since the high-temperature exhaust gas is recirculated to the intake side during the cold start, a sufficient warming effect can be obtained, and the ignitability in the internal combustion engine is improved during the cold start, thereby generating white smoke. Can be suppressed. Further, after the internal combustion engine is warmed up, that is, when the temperature of the cooling water of the internal combustion engine is higher than the second predetermined value, the first valve body is opened by controlling the valve opening of the exhaust gas flow rate control valve. And the second valve body is closed. As a result, the first introduction hole is opened and the second introduction hole is closed, so that the total flow rate of the exhaust gas flowing through the exhaust gas recirculation path passes through the exhaust heat exchanger. Therefore, the temperature of the exhaust gas passing through the exhaust gas recirculation path is reduced and the volume is reduced, so that the combustion temperature of the fuel in the internal combustion engine is effectively reduced without reducing the output of the internal combustion engine. In addition, generation of nitrogen oxides (NOx) can be reduced.

  According to the eighteenth aspect of the invention, the actual exhaust gas temperature detected by the exhaust gas temperature detecting means is substantially equal to the target value set corresponding to the load state of the internal combustion engine. Based on the temperature deviation between the gas temperature and the target value, the valve opening of the exhaust gas flow ratio control valve is feedback controlled, so that the temperature of the exhaust gas passing through the exhaust gas recirculation path is abnormally lower than the target value. There is nothing. Therefore, the combustion state in the internal combustion engine becomes good, and the rotation speed of the internal combustion engine is stabilized. Further, based on the temperature deviation between the actual exhaust gas temperature and the target value, the valve opening of the exhaust gas flow ratio control valve is adjusted so that the exhaust gas temperature detected by the exhaust gas temperature detecting means substantially matches the target value. By performing feedback control, the temperature of the exhaust gas passing through the exhaust gas recirculation path does not abnormally exceed the target value. Therefore, there is no shortage of the exhaust gas recirculation amount for recirculating a part of the exhaust gas of the internal combustion engine from the exhaust passage to the intake passage, or the ratio of the exhaust gas recirculation amount to the new intake air amount. Deterioration of emissions can be suppressed.

  The best mode of the present invention facilitates advanced control of the exhaust gas temperature in the exhaust gas recirculation path, and prevents sticking of the first valve body on the exhaust heat exchanger side of the exhaust gas flow ratio control valve due to the adhesive deposit. The first introduction hole for introducing the exhaust gas from the exhaust heat exchanger, the second introduction hole for introducing the exhaust gas from the bypass pipe, the first, in the vicinity of the downstream side of the water-cooled exhaust heat exchanger and the bypass pipe, An exhaust gas flow rate control valve having a first valve body on the exhaust heat exchanger side for adjusting the opening area of the introduction hole and a second valve body on the bypass pipe side for adjusting the opening area of the second introduction hole is provided, This was realized by opening the first valve body on the exhaust heat exchanger side of the exhaust gas flow rate control valve when the engine was stopped.

[Configuration of Example 1]
1 to 3 show a first embodiment of the present invention, and FIG. 2 is a diagram showing an overall configuration of an exhaust gas recirculation device for a diesel engine.

  The exhaust gas recirculation device of the present embodiment is used in an internal combustion engine (hereinafter referred to as an engine) 1 such as a diesel engine, for example, and is connected to an exhaust passage 2 formed in an exhaust pipe of the engine 1 to exhaust the exhaust gas. An exhaust gas recirculation passage 4 is provided for recirculating a part of the gas (exhaust gas recirculation gas: hereinafter referred to as EGR gas) to an intake passage 3 formed in the intake pipe. Note that exhaust gas flows in the exhaust passage 2 of the engine 1. Intake air filtered by the air cleaner 10 flows in the intake passage 3 of the engine 1. In the middle of the exhaust gas recirculation pipe forming the exhaust gas recirculation path 4 of this embodiment, that is, between the exhaust side exhaust gas recirculation pipe 5 branched from the exhaust pipe and the intake side exhaust gas recirculation pipe 6 joined to the intake pipe. The EGR module 7 is directly coupled in series. Here, the exhaust side exhaust gas recirculation pipe 5 of this embodiment is connected to the exhaust manifold of the exhaust pipe. The intake-side exhaust gas recirculation pipe 6 is connected to an intake manifold or surge tank of the intake pipe.

  Further, the engine 1 is provided with an engine cooling water circuit (cooling water circulation path) for circulatingly supplying engine cooling water to the EGR module 7. The engine cooling water circuit includes a cooling water pipe 8 for circulating and supplying engine cooling water from a water jacket (not shown) of the engine 1 to a cooling water inlet pipe 11 of the EGR module 7, and a cooling water outlet of the EGR module 7. A cooling water pipe 9 for circulatingly supplying (returning) engine cooling water from the pipe 12 to a water jacket of the engine 1 through a radiator (not shown) and a circulating flow of engine cooling water in the engine cooling water circuit are generated. And a water pump (not shown). In this embodiment, the engine coolant in a predetermined temperature range (for example, 75 to 80 ° C.) is returned to the water jacket of the engine 1 by exchanging heat between the engine coolant and outdoor air (outside air) using a radiator. It is configured.

  Next, the structure of the EGR module 7 of this embodiment will be briefly described with reference to FIGS. Here, FIG. 1 is a diagram showing the entire structure of an EGR module in which an exhaust gas cooling device, an exhaust gas flow rate control valve and an exhaust gas recirculation amount control valve are integrated, and FIG. 3 is an exhaust gas flow rate control valve and an exhaust gas. It is the figure which showed the gas recirculation amount control valve.

  The EGR module 7 of the present embodiment includes an exhaust gas cooling device (to be described later) that cools the EGR gas by exchanging heat between the high temperature EGR gas and the low temperature engine cooling water, and the EGR gas and the engine of the exhaust gas cooling device. The valve housing 17 is directly coupled in series downstream with respect to the flow direction of the cooling water, and is a part of the exhaust gas recirculation pipe of the exhaust gas recirculation device and one of the cooling water pipes of the engine cooling water circuit. Part.

  First, the exhaust gas cooling device has a high temperature EGR gas introduced from the exhaust gas recirculation path 4 formed in the exhaust side exhaust gas recirculation pipe 5 and a low temperature flowing from the cooling water passage formed in the cooling water pipe 8. Heat-exchanging with the engine cooling water of the engine, water-cooled exhaust heat exchanger (hereinafter referred to as EGR gas cooler) 14 for cooling the EGR gas to a desired exhaust temperature or less, and the exhaust-side exhaust gas recirculation pipe 5 The EGR gas introduced from the exhaust gas recirculation path 4 is configured by a bypass pipe 15 for bypassing the EGR gas cooler 14.

  A branch joint portion 13 for directly connecting the EGR gas cooler 14 in series to the downstream end portion of the exhaust side exhaust gas recirculation pipe 5 is integrally formed on the upstream side in the exhaust gas flow direction of the EGR gas cooler 14 of the present embodiment. It is connected to the. Further, a connecting joint portion 16 for directly connecting the EGR gas cooler 14 in series to the upstream end portion of the valve housing 17 is integrally connected to the downstream side in the exhaust gas flow direction of the EGR gas cooler 14. Further, between the branch joint portion 13 and the connection joint portion 16, a bypass pipe 15 is arranged in parallel to the EGR gas cooler 14 so as to be adjacent to the EGR gas cooler 14. These branch joint part 13, EGR gas cooler 14, bypass pipe 15 and connecting joint part 16 are exhausted to 400 to 500 ° C. or higher EGR gas containing sulfide, nitric acid, sulfuric acid, ammonium ion, acetic acid, etc. and its condensed water. Since the passage side is exposed, it is manufactured by integrally brazing and joining a metal material (for example, stainless steel) excellent in heat resistance and corrosion resistance, and the exhaust gas cooling device is integrated.

  The EGR gas cooler 14 constituting the main part of the exhaust gas cooling device is directly coupled in series to the downstream end portion of the exhaust side exhaust gas recirculation pipe 5 via the branch joint portion 13, and is connected to the valve housing via the connection joint portion 16. 17 is configured by a rectangular tubular casing 21 directly coupled in series to the upstream end of 17 and a plurality of exhaust tubes 22 accommodated in the casing 21. The casing 21 houses a plurality of exhaust tubes 22 therein, and has a cooling water passage 23 through which engine cooling water circulates around the plurality of exhaust tubes 22.

  The casing 21 that forms the outline of the EGR gas cooler 14 has two molded plates (metal plates) that are press-molded into a substantially U-shaped cross section made of a metal material (for example, stainless steel) having excellent heat resistance and corrosion resistance. ) In the plate thickness direction using a brazing material such as copper to form a square pipe. A cooling water inlet pipe 11 for allowing the engine cooling water to flow into the cooling water passage 23 from the water jacket of the engine 1 is provided at the left end of the casing 21 in the figure. A cooling water outlet is provided for leading the engine cooling water from the cooling water passage 23 into the valve housing 17 through the connecting joint portion 16. In the casing 21, a plurality of reinforcing ribs 24 for increasing boiling resistance and pressure strength are formed at equal intervals so as to be convex toward the outside.

  The plurality of exhaust tubes 22 are a plurality of flat tubes into which EGR gas is introduced from an EGR gas branching portion 30 formed in the branch joint portion 13. These exhaust tubes 22 are stacked in a plurality of stages with a predetermined gap in the minor axis direction, and the major axis direction is extended so as to cover the entire length of the casing 21 in the cylinder direction. Note that the EGR gas cooler 14 of the present embodiment has a plurality of flow directions of the engine cooling water in the cooling water passage 23 of the casing 21 in order to improve the boiling resistance of the engine cooling water passing through the cooling water passage 23. The flow direction of the EGR gas in each first exhaust gas passage 31 of the exhaust tube 22 is the same direction (parallel flow).

  Each exhaust tube 22 is formed in a flat tubular shape. Each exhaust tube 22, like the casing 21, is formed of two molded plates (metals) having a substantially U-shaped cross section made of a metal material (for example, stainless steel) having excellent heat resistance and corrosion resistance. A plurality of plates) are alternately stacked in the plate thickness direction to form a heat exchange portion having a multi-tube structure, and are manufactured by integrally brazing and joining using a brazing material such as copper. As described above, the first exhaust gas passages 31 constituting the exhaust gas cooling passages are formed in the plurality of exhaust tubes 22, and in each of the first exhaust gas passages 31, the EGR gas and A rectangular wave-shaped inner fin (not shown) for increasing the heat transfer area and improving the heat exchange efficiency between the EGR gas and the engine coolant is provided.

  The bypass pipe 15 has substantially the same dimension as the cylinder direction of the casing 21 of the EGR gas cooler 14, and is arranged in parallel with and in the vicinity of the EGR gas cooler 14. It is a substantially cylindrical tube into which EGR gas is introduced. As with the casing 21, the bypass pipe 15 brazes two molded plates (metal plates) made of a metal material (for example, stainless steel) excellent in heat resistance and corrosion resistance using a brazing material such as copper. By joining, it is formed in a cylindrical tube shape. The illustrated left end portion of the bypass pipe 15 is brazed and joined in a state of being inserted into the round hole-shaped mounting hole of the core plate 34 of the branch joint portion 13, and the illustrated right end portion of the bypass pipe 15 is connected to The joint portion 16 is brazed and joined in a state of being inserted into a round hole-shaped attachment hole of the inner partition wall portion 35 of the joint portion 16.

  In the bypass pipe 15, a second exhaust gas passage 32 for bypassing the EGR gas introduced from the EGR gas branching portion 30 from the first exhaust gas passage 31 is formed. The upstream end of the second exhaust gas passage 32 is connected to the EGR gas branching portion 30, and the downstream end of the second exhaust gas passage 32 is the second exhaust gas formed in the connection joint portion 16. It is connected in the passage 32b. The bypass pipe 15 is integrally formed with a bellows-like bellows portion 36 that can expand and contract in the cylinder direction of the bypass pipe 15.

  The branch joint portion 13 constitutes an exhaust introduction joint portion for introducing EGR gas from the exhaust gas recirculation path 4 of the exhaust side exhaust gas recirculation pipe 5, and is composed of a tank plate 33 and a core plate 34. Yes. The branch joint portion 13 is directly coupled to the upstream end portion of the casing 21 in the cylindrical direction by brazing. And the tank plate 33 and the core plate 34 use the brazing material, such as copper, for the shaping | molding plate (metal plate) which consists of metal materials (for example, stainless steel) excellent in heat resistance and corrosion resistance similarly to the casing 21. It is formed into a predetermined shape by brazing and joining. The internal space surrounded by the tank plate 33 and the recess of the core plate 34 is an EGR gas cooler for diverting (distributing) the EGR gas that has flowed into the EGR gas diversion portion 30 to the first exhaust gas passages 31. 14 inlet side tank parts are constituted.

  The internal space (inlet side tank chamber) surrounded by the tank plate 33 and the core plate 34 is configured to supply EGR gas introduced from the exhaust gas recirculation path 4 of the exhaust side exhaust gas recirculation pipe 5 to the EGR gas cooler 14. The EGR gas that is diverted into the first exhaust gas passage 31 and the second exhaust gas passage 32 of the bypass pipe 15 at a predetermined flow rate ratio or introduced from the exhaust gas recirculation passage 4 of the exhaust side exhaust gas recirculation pipe 5 is used. It functions as an EGR gas diverter 30 that introduces the entire flow rate into the first exhaust gas passage 31 of the EGR gas cooler 14. Here, the core plate 34 has square hole-shaped insertion holes for the number of the exhaust tubes 22 that are brazed and joined in the state in which the illustrated left end portions of the first exhaust gas passages 31 of the plurality of exhaust tubes 22 are inserted. Only formed.

  Similar to the casing 21, the connection joint portion 16 is manufactured by press-molding a metal plate made of a metal material (for example, stainless steel) having excellent heat resistance and corrosion resistance so as to have a predetermined shape. The connection joint portion 16 has a mounting flange portion 37 for directly connecting the downstream portion of the EGR gas cooler 14 and the bypass pipe 15 to the valve housing 17 in series. In addition, the connection joint portion 16 has square hole-shaped insertion holes for the number of the exhaust tubes 22 that are brazed and joined in a state where the right end portions of the first exhaust gas passages 31 of the plurality of exhaust tubes 22 are inserted. The internal partition wall portion 35 formed only by this is integrally formed.

  The internal space surrounded by the valve housing 17 and the recessed portion of the internal partition wall portion 35 has an outlet side tank portion (first side) of the EGR gas cooler 14 for merging the EGR gas flowing in from the first exhaust gas passages 31. An exhaust gas passage 31b is formed. Further, the connection joint portion 16 is provided on the upper side in the drawing with respect to the second exhaust gas passage 32b, and directly connects the cooling water outlet portion of the cooling water passage 23 of the casing 21 and the cooling water passage in the valve housing 17 to each other. 26 is formed. Here, the inner partition wall 35 of the present embodiment includes an upper partition wall in the figure that partitions the cooling water passage 26 and the first exhaust gas passage 31b in a liquid-tight and air-tight manner, and the first exhaust gas passage 31b and the first exhaust gas passage 31b. 2 has an illustrated lower partition wall portion that partitions the exhaust gas passage 32b in a liquid-tight and air-tight manner.

  Next, in the valve housing 17 of the present embodiment, the flow rate of EGR gas flowing in each first exhaust gas passage 31 of the EGR gas cooler 14 and the flow rate of EGR gas flowing in the second exhaust gas passage 32 of the bypass pipe 15 are set. An exhaust gas flow rate adjustment valve 18 that continuously adjusts the ratio, an exhaust gas recirculation amount control valve (EGR control valve) 19 that continuously adjusts the total flow rate of EGR gas that passes through the valve housing 17 and the like are integrated. It is attached to. Further, the valve housing 17 converts the valve opening (rotation angle) of the exhaust gas recirculation amount control valve 19 into an electric signal, and how much EGR gas is mixed in the intake air flowing in the intake passage 3, that is, An EGR amount sensor 20 that outputs an EGR gas recirculation amount (EGR amount) from the exhaust passage 2 into the intake passage 3 to an engine control device (engine control unit: hereinafter referred to as ECU) 100 is integrally mounted.

  The valve housing 17 of this embodiment is commonly used by the exhaust gas flow rate control valve 18 and the exhaust gas recirculation amount control valve 19. Therefore, as shown in FIGS. 1 and 3, the first exhaust gas introduction into which EGR gas is introduced from the first exhaust gas passage 31 of the EGR gas cooler 14 through the first exhaust gas passage 31 b is introduced into the valve housing 17. Mixing the passage 41, the second exhaust gas introduction passage 42 through which the EGR gas is introduced from the second exhaust gas passage 32 of the bypass pipe 15 through the second exhaust gas passage 32b, and the high temperature EGR gas and the low temperature EGR gas An exhaust gas recirculation path (mixture chamber) 43, a communication path 45 communicating with the exhaust gas recirculation path 43 via the exhaust gas recirculation path 44, and the communication path 45 into the intake side exhaust gas recirculation pipe 6. An exhaust gas recirculation path 46 for introducing EGR gas is formed in the exhaust gas recirculation path 4 formed. These first exhaust gas introduction path 41, second exhaust gas introduction path 42, exhaust gas recirculation path 43, exhaust gas recirculation path 44, communication path 45 and exhaust gas recirculation path 46 constitute exhaust gas recirculation path 4.

  In the exhaust gas recirculation path 43, EGR gas is introduced from the first exhaust gas introduction path 41 through the first introduction hole 51, and EGR is introduced from the second exhaust gas introduction path 42 through the second introduction hole 52. Gas is introduced. The communication passage 45 communicates with the first exhaust gas passage 31 of the EGR gas cooler 14 via the first exhaust gas introduction passage 41 and the first introduction hole 51, and is connected to the second exhaust gas passage 32 of the bypass pipe 15. 2 A valve hole of the exhaust gas recirculation amount control valve 19 communicating with the exhaust gas introduction path 42 and the second introduction hole 52 is configured. A plug 47 is attached to the opening formed at the lower end of the second exhaust gas introduction path 42 in the figure.

  In the valve housing 17, a cooling water passage 27 is formed in which engine cooling water is introduced from the cooling water outlet portion of the cooling water passage 23 of the EGR gas cooler 14 through the cooling water passage 26. A cooling water inlet provided at the left end of the cooling water passage 27 in the drawing is directly coupled in series to the cooling water passage 26 of the connection joint portion 16. A cooling water outlet pipe 12 connected to the cooling water pipe 9 is provided at the right end of the cooling water passage 27 in the figure. Note that the cooling water passage 23 of the EGR gas cooler 14 and the cooling water passage 27 of the valve housing 17 of the present embodiment are the internal component (for example, bearing) 57 side of the exhaust gas flow rate control valve 18 and the exhaust gas recirculation amount control valve 19. The internal components (for example, bearings) 76 are arranged on the side, and the internal components are more easily cooled using engine cooling water.

  The valve housing 17 of the present embodiment is integrally formed in a predetermined shape by aluminum casting or aluminum die casting, and is downstream of the connecting joint portion 16 of the exhaust gas cooling device integrated by brazing. Further, it is fastened and fixed using a screw such as a fastening bolt (not shown). In this case, the mounting flange portion 37 of the connection joint portion 16 is prevented from leaking from the coupling portion where the cooling water passage 26 of the connection joint portion 16 and the cooling water passage 27 of the valve housing 17 are connected. A rubber seal (not shown) is attached between the right end face shown in the figure and the left end face shown in the figure of the valve housing 17. Further, the EGR gas is prevented from leaking from the joint where the first exhaust gas passage 31b of the connection joint portion 16 and the first exhaust gas introduction passage 41 of the valve housing 17 are connected, and the second exhaust of the connection joint portion 16 The illustrated right end surface of the mounting flange portion 37 of the connection joint portion 16 and the valve housing 17 are illustrated so that the EGR gas does not leak from the coupling portion where the gas passage 32b and the second exhaust gas introduction path 42 of the valve housing 17 are coupled. A metal gasket (not shown) is mounted between each left end surface.

  When a metal material capable of being integrally brazed with the connection joint portion 16 is used as the material of the valve housing 17, the valve housing 17 may be brazed and joined when the exhaust gas cooling device is integrally brazed. good. In this case, after integrally brazing, each component of the exhaust gas flow rate control valve 18, each component of the exhaust gas recirculation amount control valve 19, and each component of the EGR amount sensor 20 are assembled to the valve housing 17. Like that. Here, the cooling water passage 27 of the valve housing 17 connects the internal components (for example, bearings) 57 of the exhaust gas flow rate control valve 18 and the internal components (for example, bearings) 76 of the exhaust gas recirculation amount control valve 19 with EGR gas. For the purpose of protecting from heat, the internal components (for example, bearings) 57 of the exhaust gas flow rate control valve 18 and the internal components (for example, bearings) 76 of the exhaust gas recirculation amount control valve 19 and a drive motor (described later) are surrounded. It may be provided to go around.

  The exhaust gas flow rate adjusting valve 18 is composed of first and second introduction holes 51 and 52 provided in the valve housing 17 and a metal double poppet that adjusts the opening area of the first and second introduction holes 51 and 52. Type valve 53, a metal valve shaft (shaft-like portion) 54 that reciprocates in the axial direction integrally with the double poppet type valve 53, and a valve that drives the double poppet type valve 53 and the valve shaft 54 upward in the figure. Body drive means (described later) and valve body urging means (for example, a spring) 55 for urging the double poppet type valve 53 and the valve shaft 54 downward in the figure are provided. Here, the second introduction hole 52 is formed in a metal valve seat 56.

  The double poppet type valve 53 of the present embodiment is formed in a substantially disc shape with a metal material excellent in heat resistance and corrosion resistance, such as stainless steel, and normally adjusts the opening area of the first introduction hole 51. Open type (normally open type) first valve body (first bowl-shaped part, valve) 61 and normally closed type (normally closed type) second valve body (first type) for adjusting the opening area of the second introduction hole 52 2) and a cylindrical connecting portion 63 for connecting the first and second valve bodies 61, 62, and the like, on the outer periphery of the valve holding portion on the lower end side of the valve shaft 54 in the figure. It is fitted and integrated with the valve shaft 54. Here, the double poppet type valve 53 of the present embodiment has a structure in which the first valve body 61 on the EGR gas cooler 14 side is not fully closed even when the second valve body 62 on the bypass pipe 15 side is fully opened. Yes. Further, when the second valve body 62 on the bypass pipe 15 side of the double poppet type valve 53 is fully closed, the second valve body 62 is seated on the second valve seat on the upper end side of the substantially annular valve seat 56 so that the second The introduction hole 52 is airtightly closed.

  The valve shaft 54 of the present embodiment is slidably provided in an internal component (for example, a bearing) 57 accommodated and held in the bearing support portion on the left side of the valve housing 17 in the drawing, and is the same as the double poppet type valve 53. And a valve holding portion that is integrally formed of a metal material excellent in heat resistance and corrosion resistance, such as stainless steel, and holds and fixes the double poppet type valve 53 using a fixing means such as welding. ing. Here, a large-diameter sleeve 58 is mounted on the outer periphery of the valve shaft 54. The valve housing 17 is provided with a small-diameter sleeve 59 that enters the inner diameter of the large-diameter sleeve 58. The large diameter sleeve 58 and the small diameter sleeve 59 allow fine particles contained in the EGR gas to enter into a bearing sliding portion formed between the outer periphery of the valve shaft 54 and the inner periphery of the bearing 57 to form a deposit. That is restrained. As a result, the deposit is caught in a minute gap between the outer periphery of the valve shaft 54 and the inner periphery of the bearing 57, whereby the valve shaft 54 is fixed (sticked) to the sliding surface with the bearing 57, and the exhaust gas is exhausted. The problem that the double poppet valve 53 of the gas flow rate control valve 18 does not smoothly open and close can be solved.

  The valve body driving means for driving the double poppet type valve 53 and the valve shaft 54 of the exhaust gas flow rate control valve 18 of this embodiment is a negative pressure actuated actuator that uses negative pressure. The first valve body 61 on the gas cooler 14 side is driven in the valve closing direction, and the second valve body 62 on the bypass pipe 15 side in the double poppet valve 53 is driven in the valve opening direction. The negative pressure actuated actuator controls the pressure difference between the negative pressure chamber 65a and the atmospheric pressure chamber 65b formed between the casing 60 and the thin film diaphragm 64 by an electromagnetic or electric negative pressure control valve 18a. Then, by displacing the diaphragm 64, the double poppet type valve 53 and the valve shaft 54 are reciprocally displaced in the axial direction. The center portion of the diaphragm 64 is pressed by two pressing plates 66 for fixing the illustrated upper end portion of the valve shaft 54 by fixing means such as caulking.

  Further, a negative pressure from a vacuum pump as a negative pressure source acts on the negative pressure chamber 65a via an electromagnetic or electric negative pressure control valve 18a. The electromagnetic or electric negative pressure control valve 18a can continuously change the negative pressure introduced into the negative pressure chamber 65a. Further, an intake pipe negative pressure may be used as the negative pressure source. The spring 55 is disposed in the negative pressure chamber 65a and presses the diaphragm 64 toward the atmospheric pressure chamber 65b, thereby urging the first valve body 61 in the valve opening direction and the second valve body. A spring (valve element urging means) that urges 62 in the valve closing direction. The exhaust gas flow ratio adjusting valve 18 of the present embodiment includes a cylindrical stopper 68 for holding an oil seal 67 between the bearing support portion of the valve housing 17 and the upper end side portion of the valve shaft 54 in the figure. A cylindrical guide 69 is attached.

  The exhaust gas recirculation amount control valve 19 includes a communication passage 45 provided in the valve housing 17, a metal valve (valve element) 71 that adjusts the opening area of the communication passage 45, and the valve 71. Metal valve shaft 72 operating in the rotational direction, valve body driving means (described later) for driving valve 71 and valve shaft 72 in the valve opening direction, and urging valve 71 and valve shaft 72 in the valve closing direction And a valve body biasing means (for example, a spring) 73. The communication passage 45 is formed in a metal cylindrical tube (nozzle) 74 fitted in the valve housing 17.

  The valve 71 of this embodiment is formed in a substantially disc shape from a metal material having excellent heat resistance and corrosion resistance, such as stainless steel. A seal ring 75 that can slide in contact with the inner wall surface (flow channel wall surface) of the nozzle 74 near the valve fully closed position is held on the outer periphery of the valve 71. As with the valve 71, the seal ring 75 is also formed in a substantially cylindrical shape from a metal material having excellent heat resistance and corrosion resistance, such as stainless steel. The valve shaft 72 is slidably provided in an internal component (for example, a bearing) 76 that is housed and held in the bearing support portion on the right side of the valve housing 17 in the figure. The valve holding part is formed integrally with a metal material having excellent corrosion resistance, such as stainless steel, and holds and fixes the valve 71 using a fixing means such as welding. Here, in the outer periphery of the valve shaft 72, fine particles contained in the EGR gas enter a bearing sliding portion formed between the outer periphery of the valve shaft 72 and the inner periphery of the bearing 76 to form a deposit. A guide 77 for restraining is attached. As a result, the deposit is caught in a minute gap between the outer periphery of the valve shaft 72 and the inner periphery of the bearing 76, whereby the valve shaft 72 is fixed (sticked) to the sliding surface with the bearing 76, and the exhaust gas is exhausted. The problem that the valve 71 of the gas recirculation amount control valve 19 does not smoothly open and close can be solved.

  The valve body drive means of the exhaust gas recirculation amount control valve 19 is an electric actuator composed of a power unit, and drives the valve 71 in the valve opening direction by driving the valve shaft 72 to rotate. A fixing means such as caulking is provided at the upper end of the valve shaft 72 of the present embodiment in the figure by a valve side gear 78 that is one of the components of the power transmission mechanism and the rotor 79 that is one of the components of the EGR amount sensor 20. The caulking fixing part for fixing by is integrally formed.

  The power unit includes a drive motor (not shown) that drives the valve 71 and the valve shaft 72 of the exhaust gas recirculation amount control valve 19 in the rotational direction, and the rotational power of this drive motor is the valve shaft of the exhaust gas recirculation amount control valve 19. 72 and a power transmission mechanism (in this example, a gear reduction mechanism) for transmitting to 72. The gear reduction mechanism reduces the rotation speed of the motor shaft of the drive motor so as to have a predetermined reduction ratio. The gear reduction mechanism meshes with a pinion gear (not shown) fixed to the outer periphery of the motor shaft of the drive motor and the pinion gear. An intermediate reduction gear (not shown) that rotates and a valve-side gear 78 that rotates in mesh with the intermediate reduction gear.

  Note that the valve side gear 78 is integrally formed, for example, with a resin material in a predetermined substantially annular shape, and a gear portion 80 that meshes with the intermediate reduction gear is integrally formed on the outer peripheral portion of the valve side gear 78. . Here, in the exhaust gas recirculation amount control valve 19 of the present embodiment, the bottom wall surface of the gear case portion or the motor case portion 81 integrally formed on the upper end side of the valve housing 17 and the lower end surface of the valve side gear 78 shown in the drawing. Between them, a spring 73 is mounted. A rotor 79 made of an iron-based metal material (magnetic material) is insert-molded on the inner peripheral portion of the valve side gear 78.

  The EGR amount sensor 20 is a rotation angle detection device that detects the opening degree of the exhaust gas recirculation amount control valve 19, that is, the rotation angle of the valve 71 and the valve shaft 72, and is the rotor 79 and the magnetic field generation source. A split-type permanent magnet 91, a split-type yoke (not shown) magnetized by the permanent magnet 91, and the sensor cover 92 made of an electrically insulating resin so as to face the permanent magnet 91 are integrally formed. A plurality of arranged hall elements (non-contact type rotation angle detecting elements) 93, a terminal 94 for electrically connecting the hall element 93 and the external ECU 100, and a magnetic flux to the hall element 93 are concentrated. And a stator 95 made of an iron-based metal material (magnetic material). An oil seal 96 is mounted between the bearing support portion of the valve housing 17 and the upper end side portion of the valve shaft 72 of the exhaust gas recirculation amount control valve 19 in the present embodiment.

  The ECU 100 is a microcomputer having a well-known structure that includes functions of a CPU that performs control processing and arithmetic processing, a storage device (memory such as ROM and RAM) that stores various programs and data, an input circuit, and an output circuit. Is provided. Further, when an ignition switch (not shown) is turned on (IG / ON), the ECU 100, for example, the valve opening degree of the double poppet valve 53 of the exhaust gas flow rate control valve 18 and the exhaust gas based on the control program stored in the memory. The valve opening degree of the valve 71 of the gas recirculation amount control valve 19 is electronically controlled. The ECU 100 is configured to forcibly terminate the above control based on the control program stored in the memory when the ignition switch is turned off (IG · OFF).

  Here, sensor signals from various sensors are A / D converted by an A / D converter and then input to a microcomputer built in the ECU 100. The microcomputer has a rotational speed sensor 101 for detecting the engine rotational speed (also referred to as engine rotational speed: NE) as an operational state detecting means for detecting the operational state of the engine 1, and an accelerator pedal depression amount. An accelerator opening sensor (engine load detecting means) 102 for detecting a corresponding accelerator opening (ACCP), and a temperature of intake air (intake air temperature) sucked into each cylinder of the engine 1 from the intake pipe An intake air temperature sensor 103, an intake air amount sensor (air flow meter: not shown) for detecting the flow rate (intake air amount) of intake air sucked into each cylinder of the engine 1 from the intake pipe, and engine coolant temperature ( A cooling water temperature sensor (cooling water temperature detecting means: not shown) for detecting (THW) is connected.

  Further, the microcomputer detects the temperature of the EGR gas flowing out of the EGR module 7 and flowing into the intake passage 3 through the EGR amount sensor 20 and the exhaust gas recirculation passage 4 of the intake side exhaust gas recirculation pipe 6. An exhaust temperature sensor (exhaust temperature detection means) 104 is connected to this. Here, the exhaust gas temperature sensor 104 is a temperature of the EGR gas after mixing the EGR gas flowing through each first exhaust gas passage 31 of the EGR gas cooler 14 and the EGR gas flowing through the second exhaust gas passage 32 of the bypass pipe 15. A sensor signal (voltage signal) corresponding to is output to the ECU 100.

[Control Method of Example 1]
Next, the control method of the exhaust gas recirculation device of the present embodiment will be briefly described with reference to FIGS.

  The ECU 100 is configured to control an electromagnetic valve of an injector (for example, an electromagnetic fuel injection valve) attached corresponding to each cylinder of the engine 1. That is, the basic injection amount (Q) is calculated from the engine rotation speed (NE) detected by the rotation speed sensor 101 and the accelerator opening (ACCP) detected by the accelerator opening sensor 102, and this basic injection amount (Q ) And an injection amount correction amount that takes into account the engine coolant temperature (THW), fuel temperature (THF), and the like, and a command injection amount (target injection amount: QFIN) are calculated. Further, the command injection timing (TFIN) is calculated from the engine speed (NE) and the command injection amount (QFIN).

  In the present embodiment, the exhaust gas is set so that the target EGR gas temperature (target value) commanded (determined) by the ECU 100 and the detected EGR gas temperature (detected value) detected by the exhaust temperature sensor 104 substantially coincide. The drive current value to the valve body drive means for driving the double poppet type valve 53 and the valve shaft 54 of the flow rate control valve 18, particularly the electromagnetic or electric negative pressure control valve 18 a, is changed to a known proportional integral differential control (PID control). ) Or proportional-integral control (PI control). The target EGR gas temperature is determined based on at least one of the sensor signal from the rotational speed sensor 101, the accelerator opening sensor 102, the exhaust temperature sensor 104, and the command injection amount (QFIN). The operating state is detected and determined to be an optimum value for the current operating state of the engine 1. Here, the control of the control command value (drive current value) to the electromagnetic or electric negative pressure control valve 18a is preferably performed by duty (DUTY) control. In other words, the ON / OFF ratio (energization ratio / duty ratio) of the control pulse signal per unit time is adjusted according to the temperature deviation between the target EGR gas temperature and the detected EGR gas temperature, and the exhaust gas flow ratio control valve 18 is adjusted. Duty (DUTY) control for continuously changing the valve opening (rotation angle) of the double poppet type valve 53 is used.

  In the present embodiment, the command EGR amount (target valve opening) commanded (determined) by the ECU 100 and the detected EGR amount (actual valve opening) detected by the EGR amount sensor 20 are substantially matched. The drive current value to the drive motor that rotationally drives the valve 71 and the valve shaft 72 of the exhaust gas recirculation amount control valve 19 is fed back using known proportional integral differential control (PID control) or proportional integral control (PI control). I have control. The command EGR amount detects the operating state of the engine 1 based on sensor signals and command injection amount (QFIN) from the EGR amount sensor 20, the rotation speed sensor 101, the intake air temperature sensor 103, the intake air amount sensor, etc. Amount of nitrogen oxide (NOx) generated in the exhaust gas so as to be an optimum value for the current operating state of the engine 1, that is, while suppressing a decrease in the output of the engine 1 and a decrease in the operability of the engine 1 Is determined so as to be an optimum value that can be reduced. Here, it is desirable to control the control command value (drive current value) to the drive motor by duty (DUTY) control. That is, the ON / OFF ratio (energization ratio / duty ratio) of the control pulse signal per unit time is adjusted according to the deviation between the command EGR amount (target valve opening) and the detected EGR amount (actual valve opening). Thus, duty (DUTY) control for continuously changing the valve opening (rotation angle) of the valve 71 of the exhaust gas recirculation amount control valve 19 is used.

  Next, an example of a control method of the valve opening degree of the double poppet type valve 53 of the exhaust gas flow rate control valve 18 corresponding to the operating state of the engine 1 will be described. First, when the operation of the engine 1 is stopped, the exhaust gas is used for the purpose of preventing the fine particles contained in the exhaust gas from adhering to the surface of the first valve body 61 on the EGR gas cooler 14 side to form a sticky deposit. To the electromagnetic or electric negative pressure control valve 18a, the first valve body 61 on the EGR gas cooler 14 side of the flow ratio control valve 18 is fully opened and the second valve body 62 on the bypass pipe 15 side is fully closed. Stop energization. Thus, when the operation of the engine 1 is stopped, the first introduction hole 51 for introducing the exhaust gas from the first exhaust gas passage 31 in the EGR gas cooler 14 into the exhaust gas recirculation passage (mixture chamber) 43 on the intake side is opened (fully opened). The second introduction hole 52 for introducing the exhaust gas from the second exhaust gas passage 32 in the bypass pipe 15 into the exhaust gas recirculation passage 43 on the intake side is closed (fully closed). That is, when the operation of the engine 1 is stopped, the temperature of the EGR gas passing through the exhaust gas recirculation passage 4 for recirculating the EGR gas to the intake passage 3 of the intake pipe is set high.

  Further, when the operating state of the engine 1 is cold start, that is, when the engine coolant temperature (THW) detected by the coolant temperature sensor is lower than a first predetermined value (for example, 0 ° C.), sufficient warm air to the intake air is obtained. In order to obtain the effect, the second valve body 62 on the bypass pipe 15 side is fully opened. In the present embodiment, even when the second introduction hole 52 for introducing the exhaust gas from the second exhaust gas passage 32 in the bypass pipe 15 is fully opened, the first valve body 61 on the EGR gas cooler 14 side is The first introduction hole 51 for introducing the exhaust gas from the first exhaust gas passage 31 in the gas cooler 14 is opened by a predetermined opening or more. That is, the first valve body 61 on the EGR gas cooler 14 side is not fully closed and does not sit on the valve seat.

  Further, after the warm-up operation of the engine 1 is completed (after the engine 1 is warmed up), that is, the engine coolant temperature (THW) detected by the coolant temperature sensor is a second predetermined value (higher than the first predetermined value). For example, when the temperature is higher than 80 ° C., an exhaust gas flow rate control valve is used for the purpose of effectively reducing the generation of nitrogen oxides (NOx) by lowering the combustion temperature of the fuel in the combustion chamber of each cylinder of the engine 1. The energization to the electromagnetic or electric negative pressure control valve 18a is stopped so that the first valve body 61 on the EGR gas cooler 14 side of the 18 is fully opened and the second valve body 62 on the bypass pipe 15 side is fully closed. . As a result, after the engine 1 is warmed up, the temperature of the EGR gas passing through the exhaust gas recirculation passage 4 for recirculating the EGR gas to the intake passage 3 of the intake pipe becomes sufficiently low. Specifically, the temperature of the EGR gas recirculated to the intake passage 3 of the intake pipe becomes, for example, about 120 ° C.

  Further, the engine coolant temperature (THW) detected by the coolant temperature sensor from the cold start to the warm-up time is equal to or higher than a first predetermined value (for example, 0 ° C.) and a second predetermined value (for example, 80). When the temperature is within the following temperature range, the EGR gas temperature detected by the exhaust temperature sensor 104 (the temperature of the EGR gas flowing out of the EGR module 7 and entering the intake passage 3) corresponds to the operating state of the engine 1. The valve opening degree of the double poppet valve 53 of the exhaust gas flow rate control valve 18 is set to a well-known proportional integral differential control (PID control) or proportional integral control (PI) so as to substantially match the target EGR gas temperature set by Control). As a result, the temperature of the EGR gas passing through the exhaust gas recirculation passage 4 for recirculating the EGR gas to the intake passage 3 of the intake pipe becomes the target EGR gas temperature from the cold start time to the warm-up time. Is controlled accordingly. Specifically, the temperature of the EGR gas recirculated to the intake passage 3 of the intake pipe is controlled to about 130 ° C. to 300 ° C., for example.

  Here, between the cold start time and the warm-up time, the exhaust gas temperature changes depending on the engine load. Specifically, when the engine load is low, the exhaust gas temperature is about 180 ° C., for example, and when the engine load is medium load, the exhaust gas temperature is about 350 ° C., for example. For this reason, during the period from cold start to warm-up, the EGR gas temperature is set to the target by optimizing the valve opening of the double poppet type valve 53 of the exhaust gas flow rate control valve 18 according to the engine load. The EGR gas temperature (for example, about 130 ° C. to 300 ° C.) is controlled.

[Operation of Example 1]
Next, the operation of the exhaust gas recirculation device of this embodiment will be briefly described with reference to FIGS.

  For example, when the engine 1 such as a diesel engine is started and the intake valve of the intake port formed in the cylinder head of the engine 1 is opened, the intake air filtered by the air cleaner 10 is supplied to the intake passage 3 of the intake pipe, the throttle It is distributed to the intake manifold of each cylinder through the body and surge tank, and is sucked into each cylinder of the engine 1. In the engine 1, the air is compressed until it reaches a temperature higher than the temperature at which the fuel burns, and high pressure fuel is sprayed from the injector there and combustion is performed. The combustion gas burned in each cylinder is discharged from an exhaust port formed in the cylinder head of the engine 1 and is discharged through an exhaust manifold and an exhaust passage 2 of an exhaust pipe.

  At this time, when the drive current value to the electromagnetic or electric negative pressure control valve 18a is adjusted by the ECU 100 so that the double poppet type valve 53 of the exhaust gas flow rate control valve 18 has a predetermined valve opening degree, A negative pressure is introduced into the negative pressure chamber 65a, the diaphragm 64 is displaced according to the pressure difference between the negative pressure chamber 65a and the atmospheric pressure chamber 65, and the valve shaft 54 is lifted by a predetermined lift amount in the drawing. As a result, the first valve body 61 on the EGR gas cooler 14 side of the double poppet type valve 53 is driven in the valve closing direction, so that the opening area of the first introduction hole 51 formed in the valve housing 17 has a predetermined valve opening. Adjusted to degree. At the same time, the second valve body 62 on the bypass pipe 15 side in the double poppet type valve 53 is driven in the valve opening direction so that the opening area of the second introduction hole 52 formed in the valve housing 17 has a predetermined valve opening degree. Adjusted to. Therefore, the flow rate of the EGR gas flowing in each first exhaust gas passage 31 of the EGR gas cooler 14 and the flow rate of the EGR gas flowing in the second exhaust gas passage 32 of the bypass pipe 15 depend on the operating state of the engine 1 and the EGR gas flow. Optimized according to temperature.

  On the other hand, when the drive motor is energized by the ECU 100 so that the valve 71 of the exhaust gas recirculation amount control valve 19 has a predetermined valve opening, the motor shaft of the drive motor rotates. As the motor shaft rotates, the pinion gear rotates and torque is transmitted to the intermediate reduction gear. Then, with the rotation of the intermediate reduction gear, the valve side gear 78 including the gear portion 80 that meshes with the intermediate reduction gear rotates. Thereby, the valve shaft 72 integrated with the valve side gear 78 rotates by a predetermined rotation angle, and the valve 71 of the exhaust gas recirculation amount control valve 19 opens from the valve fully closed position to the fully opened position side (valve opening direction). ). Thus, the first exhaust gas passage 31 of the EGR gas cooler 14 communicates with the first exhaust gas introduction passage 41 and the first introduction hole 51, and the second exhaust gas introduction is introduced into the second exhaust gas passage 32 of the bypass pipe 15. The opening area of the communication passage 45 communicating with the passage 42 and the second introduction hole 52 is adjusted to a predetermined valve opening. Therefore, the total flow rate of the EGR gas passing through the exhaust gas recirculation path 43, the exhaust gas recirculation path 44, the communication path 45, and the exhaust gas recirculation path 46 of the valve housing 17, that is, the EGR gas is recirculated to the intake passage 3 of the intake pipe. The total flow rate of the EGR gas passing through the exhaust gas recirculation path 4 for circulation is optimized according to the operating state of the engine 1 and the temperature of the EGR gas.

  Therefore, the EGR gas introduced from the exhaust passage 2 of the exhaust pipe into the exhaust gas recirculation path 4 formed in the exhaust side exhaust gas recirculation pipe 5 is formed in the EGR module 7 and in the intake side exhaust gas recirculation pipe 6. Then, the air flows into the intake passage 3 of the intake pipe through the exhaust gas recirculation passage 4 and is mixed with the intake air from the air cleaner 10. Here, the EGR gas that has flowed into the EGR gas branching portion 30 of the branch joint portion 13 from the exhaust side exhaust gas recirculation pipe 5 is the first exhaust gas passage 31 of the EGR gas cooler 14 and the second exhaust gas passage 32 of the bypass pipe 15. And divert at a predetermined flow rate ratio. The EGR gas that has flowed into the first exhaust gas passage 31 of the EGR gas cooler 14 is cooled by exchanging heat with the engine coolant that flows through the cooling water passage 23 of the EGR gas cooler 14, and then the first exhaust of the connection joint portion 16. It flows into the first exhaust gas introduction passage 41 of the valve housing 17 through the gas passage 31b. Then, the EGR gas that has flowed into the first exhaust gas introduction path 41 flows into the exhaust gas recirculation path 43 through the first introduction hole 51.

  On the other hand, the EGR gas that has flowed into the second exhaust gas passage 32 of the bypass pipe 15 passes through the second exhaust gas passage 32b of the connection joint portion 16 without exchanging heat with the engine cooling water, and thus the second exhaust of the valve housing 17. It flows into the gas introduction path 42. Then, the EGR gas that has flowed into the second exhaust gas introduction passage 42 flows into the exhaust gas recirculation passage 43 through the second introduction hole 52 and passes through the first introduction gas passage 31 of the EGR gas cooler 14. The EGR gas that has flowed in through 51 is mixed and controlled to an optimum temperature. Thereafter, the EGR gas flows into the intake side exhaust gas recirculation pipe 6 through the exhaust gas recirculation path 44, the communication path 45, and the exhaust gas recirculation path 46.

  Engine cooling water for cooling the EGR gas in the EGR gas cooler 14 is supplied from the water jacket (not shown) of the engine 1 through the cooling water pipe 8 and the cooling water inlet pipe 11 of the EGR module 7. The EGR gas flows into the cooling water passage 23 and takes the heat of the EGR gas flowing in the first exhaust gas passage 31 of the EGR gas cooler 14 to cool the EGR gas. Thereafter, the engine coolant flows from the coolant outlet portion of the coolant passage 23 of the EGR gas cooler 14 into the coolant passage 26 of the connection joint portion 16. The engine coolant that has flowed into the coolant passage 26 flows into the coolant passage 27 of the valve housing 17 and cools the valve housing 17 that is heated to high temperature by the heat of the EGR gas. Thereafter, the engine coolant is circulated and supplied from the coolant outlet pipe 12 of the EGR module 7 to the water jacket of the engine 1 via the radiator.

  Here, for example, during normal operation, the valve 71 of the exhaust gas recirculation amount control valve 19 is opened at an appropriate valve opening, and the first valve on the EGR gas cooler 14 side of the double poppet type valve 53 of the exhaust gas flow rate control valve 18 is used. By opening the body 61 and closing the second valve body 62 on the bypass pipe 15 side, all EGR gas introduced into the exhaust gas recirculation path 4 formed in the exhaust side exhaust gas recirculation pipe 5 is EGR. If recirculation is made to the intake passage 3 of the intake pipe via the first exhaust gas passage 31 of the gas cooler 14, the EGR gas is sufficiently cooled by the engine coolant. As a result, since the EGR gas having a low temperature and a small volume is mixed with the intake air, the combustion temperature can be lowered and the generation of NOx can be effectively reduced without lowering the output of the engine 1. it can.

  Further, for example, during cold weather, the valve 71 of the exhaust gas recirculation control valve 19 is opened to an appropriate valve opening, and the first valve body on the EGR gas cooler 14 side of the double poppet type valve 53 of the exhaust gas flow rate control valve 18 is used. 61 and the second valve body 62 on the bypass pipe 15 side are both opened, so that the EGR gas introduced into the exhaust gas recirculation path 4 formed in the exhaust side exhaust gas recirculation pipe 5 is converted into each of the EGR gas coolers 14. When the temperature of the EGR gas is optimized by diverting it to the first exhaust gas passage 31 and the second exhaust gas passage 32 of the bypass pipe 15 at a predetermined flow rate ratio, it is then recirculated to the intake passage 3 of the intake pipe. The EGR gas is recirculated while the temperature is relatively high. Thus, a sufficient warming effect on the intake air can be obtained, the ignitability in the engine 1 can be improved, and the generation of white smoke can be prevented.

  Further, when the temperature of the intake air is lowered by cooling the EGR gas, the NOx emission amount tends to decrease. However, under relatively low engine speed and low load operating conditions, the EGR gas is Cooling increases the emission of exhaust particulates (particulate matter: PM). For this reason, the first valve body 61 on the EGR gas cooler 14 side and the second valve body 62 on the bypass pipe 15 side of the double poppet type valve 53 of the exhaust gas flow rate control valve 18 are appropriately controlled according to the operating state of the engine 1. By controlling to the opening degree, it is possible to change the temperature of the EGR gas so as to be an optimum temperature, and to simultaneously reduce the NOx emission amount and the PM emission amount.

[Effect of Example 1]
As described above, in the exhaust gas flow rate control valve 18 of the present embodiment, when the energization of the electromagnetic or electric negative pressure control valve 18a is stopped when the operation of the engine 1 is stopped, the exhaust gas flow ratio adjustment valve 18 enters the negative pressure chamber 65a. The introduction of the negative pressure is eliminated, and the pressure difference between the atmospheric pressure chamber 65 and the negative pressure chamber 65a is reduced. Therefore, the diaphragm 64 and the valve shaft 54 are moved downward in the figure by the urging force of the spring 55, and the second valve body 62 on the bypass pipe 15 side of the double poppet type valve 53 is moved to the second upper end side of the valve seat 56 on the upper end side in the figure. 2 Sit on the valve seat. As a result, the first valve body 61 on the EGR gas cooler 14 side of the exhaust gas flow ratio control valve 18 fully opens the first introduction hole 51, and the second valve body 62 on the bypass pipe 15 side fully opens the second introduction hole 52. Close. That is, when the engine is stopped, the first introduction hole 51 for introducing exhaust gas from the first exhaust gas passage 31 in the EGR gas cooler 14 into the exhaust gas recirculation passage 43 on the intake side is opened (fully opened), and the inside of the bypass pipe 15 The second introduction hole 52 for introducing the exhaust gas from the second exhaust gas passage 32 into the exhaust gas recirculation passage 43 on the intake side is closed (fully closed).

  Here, when the EGR gas that generally passes through the exhaust tube 22 (first exhaust gas passage 31) of the EGR gas cooler 14 is cooled by the engine coolant that circulates in the cooling water passage 23 of the casing 21, the EGR gas The adhesiveness of the fine particles contained therein is increased. In the type in which the first valve body 61 on the EGR gas cooler 14 side of the exhaust gas flow ratio control valve 18 is seated on the first valve seat of the valve seat, sticky fine particles adhere to the surface of the first valve body 61 and stick. If a quality deposit is formed, an adhesive deposit may be deposited across the first valve body 61 and the first valve seat. In this case, the first valve body 61 is fixed to the first valve seat at the next engine start, and the double poppet type valve 53 of the exhaust gas flow rate control valve 18, particularly the first valve body on the EGR gas cooler 14 side. There was a possibility that the control responsiveness of the valve opening of 61 would be deteriorated.

  However, as in the present embodiment, when the engine is stopped, only the first valve body 61 on the EGR gas cooler 14 side of the double poppet type valve 53 of the exhaust gas flow rate control valve 18 is opened. Even if fine particles contained in the exhaust gas adhere to the surface of the first valve body 61 on the EGR gas cooler 14 side and the periphery of the first introduction hole 51 to form a sticky deposit, the exhaust gas flow rate control valve 18 Since no sticky deposit can be accumulated across the first valve body 61 and the valve housing (first valve seat or valve seat) 17 on the EGR gas cooler 14 side, the exhaust gas flow ratio control valve 18 The first valve body 61 on the EGR gas cooler 14 side does not stick. Thereby, for example, the double poppet type valve 53 of the exhaust gas flow rate adjusting valve 18, particularly the first valve body 61 on the EGR gas cooler 14 side, can be opened and closed smoothly by a negative pressure actuator such as a diaphragm 64. The control responsiveness of the valve opening degree of the double poppet type valve 53 of the valve 18, particularly the first valve body 61 on the EGR gas cooler 14 side can be improved.

  Here, as described above, during the period from the cold start to the warm-up time, the exhaust gas recirculation path 4 of the intake side exhaust gas recirculation pipe 6 flows out of the EGR module 7 toward the intake air path 3. It is necessary to control the EGR gas temperature to a target EGR gas temperature (for example, about 130 ° C. to 300 ° C.) set in accordance with the operating state (for example, engine load) of the engine 1. Therefore, in the present embodiment, the exhaust gas recirculation is performed by disposing the double poppet type valve 53 of the exhaust gas flow rate control valve 18 in the vicinity of the downstream side of the exhaust gas cooling device constituted by the EGR gas cooler 14, the bypass pipe 15 and the like. When changing the exhaust gas temperature toward the intake passage 3 through the passage 4, the opening degree of the double poppet type valve 53 of the exhaust gas flow ratio control valve 18 is set by the volume (length) of the exhaust gas cooling device. Control responsiveness is improved.

  In addition, the exhaust gas flow rate is determined based on the temperature deviation between the exhaust gas temperature and the target EGR gas temperature so that the exhaust gas temperature toward the intake passage 3 in the exhaust gas recirculation path 4 substantially matches the target EGR gas temperature. By performing feedback control of the valve opening degree of the double poppet type valve 53 of the ratio control valve 18, the temperature of the exhaust gas flowing through the exhaust gas recirculation passage 4 into the intake passage 3 is abnormally lower than the target EGR gas temperature (under) Never shoot). Therefore, the combustion state (engine combustion) in the combustion chamber of each cylinder of the engine 1 becomes good, and the rotation speed of the engine 1 is stabilized. Further, based on the temperature deviation between the exhaust gas temperature and the target EGR gas temperature, the exhaust gas flow rate ratio is set so that the exhaust gas temperature traveling in the exhaust gas recirculation path 4 toward the intake passage 3 substantially matches the target EGR gas temperature. By performing feedback control of the valve opening degree of the double poppet type valve 53 of the control valve 18, the temperature of the exhaust gas that flows in the exhaust gas recirculation passage 4 into the intake passage 3 is abnormally higher than the target EGR gas temperature (overshoot). Do not). Therefore, the EGR gas recirculation amount (EGR amount) or the EGR rate that is the ratio of the EGR amount to the new intake air amount is not deficient, and the deterioration of the emission of the engine 1 can be suppressed.

  That is, the valve opening degree of the double poppet type valve 53 of the exhaust gas flow rate control valve 18 is fed back based on the temperature deviation between the exhaust gas temperature passing through the exhaust gas recirculation passage 4 into the intake passage 3 and the target EGR gas temperature. By controlling, the exhaust gas temperature traveling in the exhaust gas recirculation passage 4 into the intake passage 3 is quickly converged to the target EGR gas temperature without abnormally overshooting or undershooting the target EGR gas temperature. Further, it becomes easy to control the exhaust gas temperature in the exhaust gas recirculation path 4 toward the intake passage 3 at a high level. Therefore, disposing the double poppet type valve 53 of the exhaust gas flow rate control valve 18 in the vicinity of the downstream side of the exhaust gas cooling device configured by the EGR gas cooler 14 and the bypass pipe 15 or the like makes it possible to arrange the exhaust gas flow rate control valve 18. The control response of the valve opening degree of the double poppet type valve 53 is also very effective.

  Further, in the exhaust gas recirculation device of this embodiment, the engine cooling water is further provided between the exhaust side exhaust gas recirculation pipe 5 branched from the exhaust pipe and the intake side exhaust gas recirculation pipe 6 joined to the intake pipe. Between the cooling water pipe 8 and the cooling water pipe 9 of the circuit, an exhaust gas cooling device constituted by a branch joint part 13, an EGR gas cooler 14, a bypass pipe 15 and a connection joint part 16, and the like, and an exhaust gas flow rate control valve The EGR module 7 including 18 component parts, the exhaust gas recirculation amount control valve 19, and the valve housing 17 that holds the EGR amount sensor 20 is directly coupled in series. Thus, the exhaust gas recirculation pipe connecting the EGR gas cooler 14 and the bypass pipe 15 and the exhaust gas flow ratio control valve 18, and the exhaust gas recirculation pipe connecting the exhaust gas flow ratio control valve 18 and the exhaust gas recirculation amount control valve 19. The cooling water pipe for connecting the EGR gas cooler 14 and the exhaust gas flow rate control valve 18 and the cooling water pipe for connecting the exhaust gas flow ratio control valve 18 and the exhaust gas recirculation amount control valve 19 are not required. Can be reduced. Therefore, it is possible to improve the assembling property of the EGR gas cooler 14 and the bypass pipe 15 and the exhaust gas flow rate control valve 18, and the assembling property of the exhaust gas flow rate control valve 18 and the exhaust gas recirculation amount control valve 19. The passage lengths of the exhaust gas recirculation passage 4 and the cooling water passage can be greatly shortened, so that the piping (layout) can be easily performed and the mountability to the vehicle can be further improved.

Further, in the present embodiment, the EGR gas cooler 14 and the bypass are configured by arranging the EGR gas cooler 14 and the bypass pipe 15 in parallel and in the vicinity in the middle of the exhaust gas recirculation path 4. The physique of the exhaust gas cooling device can be reduced in size as compared with the conventional technique in which the pipe 15 is provided apart. Accordingly, the piping can be easily handled and the exhaust gas cooling device can be easily assembled, so that the mounting property on the vehicle can be improved.
In this embodiment, each component of the exhaust gas flow rate control valve 18 and each component of the exhaust gas recirculation control valve 19 are held in one valve housing 17, that is, one valve housing. The exhaust gas flow rate control valve 18 and the exhaust gas recirculation amount control valve 19 are integrated in series by using 17 in common (common use). As a result, in the prior art, the exhaust gas flow rate adjustment valve 18 and the exhaust gas recirculation amount control valve 19 are connected via the exhaust gas recirculation pipe, so that the exhaust gas recirculation pipe between the two contacts the outside air. Although the temperature variation of the EGR gas has been a problem, the temperature of the EGR gas passing through the exhaust gas recirculation path 4 of the valve housing 17 is stabilized by flowing engine cooling water into the cooling water path 27 of the valve housing 17. In addition, since the passage length of the exhaust gas recirculation passage 4 is shortened, the temperature variation of the EGR gas can be suppressed.

Further, the heat of the EGR gas and the bypass pipe 15 that have become low temperature by passing through the EGR gas cooler 14 are passed through the valve housing 17 around the exhaust gas recirculation path of the exhaust gas flow rate control valve 18 and the exhaust gas recirculation control valve 19. Since the heat of the EGR gas that maintains the high temperature by passing through is efficiently transmitted together, the temperature of the valve housing 17 that is heated to absorb the heat of the EGR gas becomes close to the temperature of the EGR gas. The temperature of the EGR gas flowing in the exhaust gas recirculation path of the valve housing 17 is stabilized.
Further, since the passage length of the exhaust gas recirculation passage 4 is shortened, the EGR gas flowing in the first exhaust gas passages 31 of the EGR gas cooler 14 and the EGR gas flowing in the second exhaust gas passage 32 of the bypass pipe 15. In order to improve the detection accuracy of the exhaust gas temperature sensor 104 that detects the temperature of the EGR gas after mixing with the exhaust gas, the control response of the double poppet valve 53 of the exhaust gas flow rate control valve 18 and the exhaust gas return The control responsiveness of the valve opening degree of the valve 71 of the flow control valve 19 can be improved.

  Further, the exhaust gas flow rate control valve 18 and the exhaust gas recirculation amount control valve 19 are formed in the exhaust gas flow rate control valve 18 by commonly using one valve housing 17 having a cooling water passage 27. The cooling water passage and the cooling water passage formed in the exhaust gas recirculation amount control valve 19 can be integrated. This eliminates the need for a cooling water pipe that connects the cooling water passage of the exhaust gas flow ratio control valve 18 and the cooling water passage of the exhaust gas recirculation amount control valve 19, and therefore passes through the cooling water pipe therebetween. The engine coolant does not exchange heat with the outside air, and the temperature of the engine coolant does not become unstable. Therefore, the temperature of the EGR gas flowing in the exhaust gas recirculation path of the valve housing 17 can be stabilized, the control response of the valve opening degree of the double poppet type valve 53 of the exhaust gas flow rate control valve 18 and the exhaust gas return. The control responsiveness of the valve opening degree of the valve 71 of the flow control valve 19 can be improved.

  Further, in the present embodiment, the exhaust gas cooling device, in particular, the EGR gas cooler 14 and the exhaust gas flow rate control valve 18 are directly connected and integrated in series via the connection joint portion 16. As a result, in the conventional technique, the EGR gas cooler 14 and the exhaust gas flow rate control valve 18 are connected via the exhaust gas recirculation pipe, and the heat transfer efficiency between the two is poor. That is, the heat of the EGR gas is transmitted to the internal components (for example, bearings) 57 of the exhaust gas flow rate control valve 18 through the valve housing 17 when mixing, but the EGR gas cooler 14 and the exhaust gas flow rate control valve 18 are mixed. , The heat of the low-temperature EGR gas cooled by the engine coolant from the connection joint portion 16 is directly transmitted to the valve housing 17 and is heated by the heat of the high-temperature EGR gas flowing directly from the bypass pipe 15. The valve housing 17 to be converted can be efficiently cooled. Thereby, by integrating the EGR gas cooler 14 and the exhaust gas flow rate control valve 18, the heat transfer efficiency is improved, and the internal components of the exhaust gas flow rate control valve 18 can be efficiently cooled.

  Further, in this embodiment, the exhaust gas flow ratio control valve 18 has an internal component (for example, a bearing) 57 and an exhaust gas recirculation amount control valve 19 having an internal component (for example, a bearing) 76 that accommodates and holds the exhaust in the valve housing 17. The EGR gas cooler 14 is cooled on the internal component (for example, bearing) 57 side of the exhaust gas flow rate control valve 18 and the internal component (for example, bearing) 76 side of the exhaust gas recirculation amount control valve 19 with respect to the gas reflux path 4. A cooling water passage 27 into which engine cooling water flows from the water passage 23 through the cooling water passage 26 is formed. Then, the EGR gas cooler 14 is disposed on the internal component (for example, bearing) 57 side of the exhaust gas flow rate control valve 18 and the internal component (for example, bearing) 76 side of the exhaust gas recirculation amount control valve 19 with respect to the bypass pipe 15. It is arranged. As a result, the exhaust gas flow ratio control valve 18 is cooled by cooling the valve housing 17 using the engine coolant directly introduced into the coolant passage 27 from the coolant passage 23 of the EGR gas cooler 14 through the coolant passage 26. The internal components (for example, bearings) 57 and the internal components (for example, bearings) 76 of the exhaust gas recirculation amount control valve 19 can be efficiently cooled.

  Further, the exhaust gas flow ratio adjusting valve 18 of the present embodiment employs a normally open type (normally open type) valve as the first valve body 61 on the EGR gas cooler 14 side, and the second valve body on the bypass pipe 15 side. By adopting a normally closed type (normally closed type) valve as 62, when a failure occurs, that is, when the valve body drive means of the exhaust gas flow ratio control valve 18 is uncontrollable, an abnormal valve closing (for example, exhaust Even when the double poppet type valve 53 and the valve shaft 54 of the gas flow ratio control valve 18 are fixed without being lifted), the second valve body 62 on the bypass pipe 15 side of the double poppet type valve 53 is closed. However, the first valve body 61 on the EGR gas cooler 14 side of the double poppet type valve 53 is opened by a predetermined valve opening. As a result, even at the time of failure, the low-temperature exhaust gas cooled by passing through the EGR gas cooler 14 enters the exhaust gas recirculation path of the valve housing 17 of the exhaust gas flow rate control valve 18 and the exhaust gas recirculation amount control valve 19. Will flow in. Thereby, the internal components (for example, bearing) 57 of the exhaust gas flow rate control valve 18 and the internal components (for example, bearing) 76 of the exhaust gas recirculation amount control valve 19 can be protected from the heat of the high-temperature exhaust gas.

  Further, when a failure occurs, that is, when the valve body drive means of the exhaust gas flow rate control valve 18 is uncontrollable, the valve opening abnormality (for example, the double poppet type valve 53 and the valve shaft 54 of the exhaust gas flow rate control valve 18 are In the double poppet type valve 53, the first valve body 61 on the EGR gas cooler 14 side and the second valve body 62 on the bypass pipe 15 side are both opened. As a result, even in the case of a failure, the low-temperature exhaust gas cooled by passing through the EGR gas cooler 14 is mixed with the high-temperature exhaust gas passing through the bypass pipe 15, thereby cooling the high-temperature exhaust gas. . Thereby, the internal components (for example, bearing) 57 of the exhaust gas flow rate control valve 18 and the internal components (for example, bearing) 76 of the exhaust gas recirculation amount control valve 19 can be protected from the heat of the high-temperature exhaust gas.

In addition, the exhaust gas flow ratio adjusting valve 18 of the present embodiment has a second introduction hole 52 through which the second valve body 62 on the bypass pipe 15 side introduces exhaust gas from the second exhaust gas passage 32 in the bypass pipe 15. When fully open, the first valve body 61 on the EGR gas cooler 14 side opens the first introduction hole 51 for introducing exhaust gas from the first exhaust gas passage 31 in the EGR gas cooler 14 by a predetermined opening or more. . That is, even when high-temperature exhaust gas is introduced from the second exhaust gas passage 32 in the bypass pipe 15 through the second introduction hole 52, the EGR gas cooler is configured so that the first introduction hole 51 is not fully closed. Due to the low-temperature exhaust gas introduced from the first exhaust gas passage 31 in the engine 14 through the first introduction hole 51, internal components (for example, bearings) 57 of the exhaust gas flow rate control valve 18 and the exhaust gas recirculation amount control valve Nineteen internal components (eg, bearings) 76 can be cooled.
Accordingly, the internal component (for example, bearing) 57 of the exhaust gas flow rate control valve 18 and the internal component (for example, bearing) 76 of the exhaust gas recirculation amount control valve 19 can be protected from the heat of the high-temperature exhaust gas. The sliding failure of the valve shaft 54 of the ratio control valve 18 and the sliding failure of the valve shaft 72 of the valve 71 of the exhaust gas recirculation control valve 19 can be prevented, and the double poppet type valve 53 of the exhaust gas flow rate control valve 18 can be prevented. The control response of the valve opening and the control response of the valve opening of the valve 71 of the exhaust gas recirculation amount control valve 19 can be improved.

In addition, a plurality of reinforcing ribs 24 are formed at equal intervals in the casing 21 forming the outline of the EGR gas cooler 14 so as to be convex toward the outside. As a result, concave portions that cause turbulent flow in the engine coolant passing through the coolant passage 23 formed in the EGR gas cooler 14 are formed on the inner wall side of the plurality of reinforcing ribs 24. Therefore, it is difficult to form a stagnation part of the engine cooling water in the cooling water passage 23, so that it is possible to prevent the engine cooling water from absorbing the heat of the EGR gas and excessively heating (boiling) in the stagnation part. In other words, the cooling performance of the EGR gas passing through the first exhaust gas passage 31 of the EGR gas cooler 14 can be prevented from being lowered, and an excessive pressure increase in the casing 21 of the EGR gas cooler 14 can be prevented. It becomes an exhaust gas cooling device.
In the present embodiment, the bellows-like bellows portion 36 that can be expanded and contracted in the cylinder direction of the bypass pipe 15 is formed integrally with the bypass pipe 15. As a result, the difference in thermal expansion between the EGR gas cooler 14 that cools the high-temperature exhaust gas with the engine cooling water and becomes the low-temperature portion and the bypass pipe 15 that passes the high-temperature exhaust gas as it is and becomes the high-temperature portion is Can be absorbed. Thereby, it becomes an exhaust-gas cooling device excellent in durability.

  FIG. 4 shows a second embodiment of the present invention. FIGS. 4 (a) and 4 (b) show an EGR module in which an exhaust gas cooling device, an exhaust gas flow rate control valve and an exhaust gas recirculation amount control valve are integrated. It is the figure which showed the main structures.

In the present embodiment, a spiral heat transfer fin 29 is provided in a cooling water inlet portion 28 provided at the left end of the cooling water passage 27 formed in the valve housing 17, thereby passing through the valve housing 17. The heat of the valve housing 17 heated to high temperature by the exhaust gas can be efficiently cooled using the engine coolant that circulates in the coolant passage 27. As a result, the heat transfer efficiency (heat radiation performance) of the engine cooling water is further improved, so that the internal components (for example, the bearings) 57 of the exhaust gas flow rate control valve 18 and the internal configuration of the exhaust gas recirculation amount control valve 19 are improved. The part (for example, bearing) 76 can be efficiently cooled using engine cooling water.
Accordingly, the internal component (for example, bearing) 57 of the exhaust gas flow rate control valve 18 and the internal component (for example, bearing) 76 of the exhaust gas recirculation amount control valve 19 can be protected from the heat of the high-temperature exhaust gas. The sliding failure of the valve shaft 54 of the ratio control valve 18 and the sliding failure of the valve shaft 72 of the valve 71 of the exhaust gas recirculation control valve 19 can be prevented, and the double poppet type valve 53 of the exhaust gas flow rate control valve 18 can be prevented. The control response of the valve opening and the control response of the valve opening of the valve 71 of the exhaust gas recirculation amount control valve 19 can be improved.

[Modification]
In the present embodiment, the valve body driving means of the exhaust gas flow rate control valve 18 is constituted by a negative pressure actuated actuator provided with an electromagnetic or electric negative pressure control valve 18a. The valve body drive means is constituted by an electric actuator provided with a power unit including a drive motor and a power transmission mechanism (for example, a gear reduction mechanism) or an electromagnetic actuator such as an electromagnetic flow control valve. Also good. In this embodiment, the valve body driving means of the exhaust gas recirculation amount control valve 19 is an electric actuator provided with a power unit that includes a drive motor and a power transmission mechanism (a gear reduction mechanism in this example). However, it may be configured by an electromagnetic actuator such as an electromagnetic or electric negative pressure control valve or an electromagnetic flow control valve.

  In this embodiment, the valve housing of the exhaust gas flow rate control valve 18 is directly connected in series to the downstream side of the exhaust gas cooling device (EGR gas cooler 14 and bypass pipe 15), and the exhaust gas flow rate control valve 18 The valve housing of the exhaust gas recirculation amount control valve 19 is directly connected in series downstream, and the exhaust gas flow rate control valve 18 and the exhaust gas recirculation amount control valve 19 share one valve housing 17. However, only the valve housing of the exhaust gas recirculation amount control valve 19 may be directly coupled in series to the downstream side of the EGR gas cooler 14. Even in this case, the exhaust gas recirculation pipe and the cooling water pipe that connect the EGR gas cooler 14 and the exhaust gas recirculation amount control valve 19 become unnecessary, and the number of parts can be reduced. In addition, the assembly of the EGR gas cooler 14 and the exhaust gas recirculation amount control valve 19 can be improved, and the lengths of the exhaust gas recirculation passage and the cooling water passage can be greatly shortened. This facilitates the mounting on the vehicle.

  In addition, the valve housing of the exhaust gas flow ratio control valve 18 is disposed close to the downstream side of the EGR gas cooler 14 or the bypass pipe 15 to connect the EGR gas cooler 14 or the bypass pipe 15 and the exhaust gas flow ratio control valve 18. The exhaust gas recirculation pipe and the cooling water pipe may be shorter than the conventional technology. Further, a valve housing of the exhaust gas recirculation amount control valve 19 is disposed close to the downstream side of the exhaust gas flow rate control valve 18 so that the exhaust gas flow rate control valve 18 and the exhaust gas recirculation amount control valve 19 are coupled. The exhaust gas recirculation pipe and the cooling water pipe may be shorter than the conventional technology.

  In the present embodiment, a valve (valve) of the exhaust gas flow ratio adjusting valve 18 is a double poppet valve 53 that adjusts the opening area of the first and second introduction holes 51 and 52, and the double poppet valve 53 The valve shaft 54 that reciprocates integrally in the axial direction, and further includes a double poppet type valve 53, a first valve body 61 of a normally open type that adjusts the opening area of the first introduction hole 51, and a second introduction. Although constituted by the normally closed second valve body 62 that adjusts the opening area of the hole 52, the valve (valve body) of the exhaust gas flow rate adjusting valve 18 is connected to the EGR gas cooler (water-cooled exhaust heat exchanger) 14 side. You may comprise by the normally open type valve body (for example, poppet type valve) which adjusts the opening area of only the 1st introduction hole 51 of this. Further, the valve body such as the double poppet type valve 53 or the poppet type valve and the valve shaft 54 may be integrally formed of a metal material to reduce the number of parts and the number of assembling steps, thereby further reducing the cost.

1 is a partial cross-sectional view showing an entire structure of an EGR module in which an exhaust gas cooling device, an exhaust gas flow rate control valve, and an exhaust gas recirculation amount control valve are integrated (Example 1). 1 is a configuration diagram illustrating an overall configuration of an exhaust gas recirculation device for a diesel engine (Example 1). FIG. FIG. 3 is a cross-sectional view showing an exhaust gas flow rate control valve and an exhaust gas recirculation amount control valve (Example 1). (A) is sectional drawing which showed the main structures of the EGR module which integrated the exhaust gas cooling device, the exhaust gas flow ratio control valve, and the exhaust gas recirculation amount control valve, (b) is the A section enlarged view of (a). (Example 2).

Explanation of symbols

1 Engine (for example, an internal combustion engine such as a diesel engine)
2 Exhaust passage of exhaust pipe 3 Intake passage of intake pipe 4 Exhaust gas recirculation path 5 Exhaust side exhaust gas recirculation pipe 6 Intake side exhaust gas recirculation pipe 7 EGR module 8 Cooling water pipe 9 Cooling water pipe 11 Cooling water inlet pipe of EGR module 12 Cooling water outlet pipe of EGR module 14 EGR gas cooler (water-cooled exhaust heat exchanger)
15 Bypass piping 17 Valve housing (housing)
18 Exhaust gas flow ratio control valve 19 Exhaust gas recirculation control valve 20 EGR amount sensor 23 EGR gas cooler cooling water passage 27 Valve housing cooling water passage 29 Heat transfer fin 31 First exhaust gas passage of EGR gas cooler 32 First bypass gas passage 2 exhaust gas passage 36 bellows portion 41 first exhaust gas introduction passage 42 second exhaust gas introduction passage 43 exhaust gas recirculation passage (mixture chamber)
44 exhaust gas recirculation path 45 communication path 46 exhaust gas recirculation path 51 first introduction hole 52 second introduction hole 53 double poppet type valve of exhaust gas flow ratio control valve 54 valve shaft (shaft-shaped part) of exhaust gas flow ratio control valve
55 Exhaust Gas Flow Ratio Control Valve Spring (Valve Energizing Means)
57 Internal components of exhaust gas flow ratio control valve (bearing)
61 Normally open type first valve (EGR gas cooler side first bowl)
62 Normally closed type second valve body (second flange on the bypass piping side)
71 Valve of exhaust gas recirculation amount control valve
72 Valve shaft of exhaust gas recirculation control valve 73 Spring of exhaust gas recirculation control valve (valve element urging means)
76 Internal components of exhaust gas recirculation control valve (bearing)
100 ECU (engine control unit, engine control device)
101 Rotational speed sensor (operating state detection means)
102 Accelerator opening sensor (operating state detection means)
103 Intake air temperature sensor (operating state detection means)
104 Exhaust temperature sensor (exhaust gas temperature detection means)

Claims (18)

(A) an exhaust gas recirculation path for recirculating a part of the exhaust gas of the internal combustion engine to the intake side;
(B) an exhaust gas recirculation amount control valve for continuously or stepwise adjusting the total flow rate of exhaust gas passing through the exhaust gas recirculation path;
(C) a water-cooled exhaust heat exchanger that is provided in the middle of the exhaust gas recirculation path and cools the exhaust gas flowing in the exhaust gas recirculation path;
(D) a bypass pipe that is provided in the middle of the exhaust gas recirculation path and bypasses the exhaust gas flowing in the exhaust gas recirculation path from the exhaust heat exchanger;
(E) Exhaust gas that is provided in the middle of the exhaust gas recirculation path and continuously or stepwise adjusts the ratio of the flow rate of exhaust gas flowing through the exhaust heat exchanger and the flow rate of exhaust gas flowing through the bypass pipe In an exhaust gas recirculation device equipped with a gas flow ratio control valve,
The exhaust gas flow ratio control valve is provided in the vicinity of the exhaust heat exchanger and the downstream side of the bypass pipe,
A first introduction hole for introducing exhaust gas from the exhaust heat exchanger to the intake side;
A second introduction hole for introducing exhaust gas from the bypass pipe to the intake side;
And a valve for adjusting an opening area of at least the first introduction hole of the two first and second introduction holes,
An exhaust gas recirculation device configured to open the valve when the operation of the internal combustion engine is stopped. The exhaust gas recirculation device according to claim 1,
The valve includes a normally open first valve body that adjusts an opening area of the first introduction hole, and a normally closed second valve body that adjusts an opening area of the second introduction hole,
The exhaust gas flow rate control valve is configured such that when the second valve body fully opens the second introduction hole, the first valve body opens the first introduction hole by a predetermined opening or more. An exhaust gas recirculation device characterized by the above. The exhaust gas recirculation device according to claim 2,
The exhaust gas flow rate control valve is configured such that the first valve body is opened and the second valve body is closed when the operation of the internal combustion engine is stopped. Exhaust gas recirculation device. The exhaust gas recirculation device according to claim 2 or 3,
The valve includes a substantially circular first hook-shaped portion constituting the first valve body, a substantially circular second hook-shaped portion constituting the second valve body, the first hook-shaped portion, and the second hook-shaped portion. An exhaust gas recirculation device comprising a double poppet type valve having a shaft-like portion that reciprocates integrally with the portion. The exhaust gas recirculation device according to any one of claims 2 to 4, wherein the exhaust gas flow rate control valve includes:
An actuator for driving the first valve body in a valve closing direction and driving the second valve body in a valve opening direction;
And an exhaust gas recirculation device comprising valve body urging means for urging the first valve body in the valve opening direction and urging the second valve body in the valve closing direction. The exhaust gas recirculation device according to any one of claims 1 to 5, wherein the exhaust heat exchanger includes an exhaust gas passage tube that forms a first exhaust gas passage therein.
The bypass pipe has a second exhaust gas passage for bypassing the exhaust gas from the first exhaust gas passage inside,
The exhaust gas flow rate control valve has a mixing chamber for mixing high-temperature exhaust gas and low-temperature exhaust gas inside,
The mixture chamber communicates with the first exhaust gas passage of the exhaust gas passage pipe through the first introduction hole, and communicates with the second exhaust gas passage of the bypass pipe through the second introduction hole. An exhaust gas recirculation device.   The exhaust gas recirculation device according to any one of claims 1 to 6, wherein the exhaust gas recirculation amount control valve communicates with the exhaust heat exchanger via the first introduction hole. A communication passage communicating with the bypass pipe via the second introduction hole, a valve body for adjusting an opening area of the communication passage, an actuator for driving the valve body in a valve opening direction, and a valve body in a valve closing direction. An exhaust gas recirculation device comprising valve body urging means for urging the gas.   The exhaust gas recirculation device according to any one of claims 1 to 7, wherein the exhaust heat exchanger and the bypass pipe are arranged in parallel and in the vicinity of the exhaust gas recirculation path. An exhaust gas recirculation device comprising an exhaust gas cooling device arranged in   The exhaust gas recirculation device according to any one of claims 1 to 8, wherein the bypass pipe has a dimension substantially the same as a cylinder dimension of the exhaust heat exchanger, An exhaust gas recirculation device having a bellows-like bellows portion capable of expanding and contracting in a pipe direction of a pipe.   The exhaust gas recirculation device according to any one of claims 1 to 9, wherein the exhaust heat exchanger, the bypass pipe, and the exhaust gas flow rate control valve are provided in the middle of the exhaust gas recirculation path. And an exhaust gas recirculation device characterized by being directly coupled in series. The exhaust gas recirculation device according to any one of claims 1 to 10,
An exhaust gas recirculation device in which the exhaust gas flow ratio control valve and the exhaust gas recirculation amount control valve are directly coupled in series in the middle of the exhaust gas recirculation path. The exhaust gas recirculation device according to any one of claims 1 to 11,
An exhaust gas recirculation device characterized in that an internal component of the exhaust gas flow rate control valve and an internal component of the exhaust gas recirculation amount control valve are accommodated and held in one housing. The exhaust gas recirculation device according to any one of claims 1 to 12,
A cooling water circulation path for circulating the cooling water of the internal combustion engine in the order of the exhaust heat exchanger, the exhaust gas flow rate control valve, and the exhaust gas recirculation amount control valve;
An exhaust gas recirculation device in which the exhaust heat exchanger, the exhaust gas flow rate control valve, and the exhaust gas recirculation amount control valve are directly coupled in series in the middle of the cooling water circulation path. The exhaust gas recirculation device according to claim 13,
The housing that houses and holds the internal components of the exhaust gas flow rate control valve and the internal components of the exhaust gas recirculation amount control valve is an internal component of the exhaust gas flow rate control valve with respect to the exhaust gas recirculation path. A cooling water passage constituting a part of the cooling water circulation path on the side and the internal component side of the exhaust gas recirculation amount control valve,
The exhaust heat exchanger is disposed on an internal component side of the exhaust gas flow rate control valve and an internal component side of the exhaust gas recirculation amount control valve with respect to the bypass pipe. Gas recirculation device. The exhaust gas recirculation device according to claim 13,
The housing that houses and holds the internal components of the exhaust gas flow rate control valve and the internal components of the exhaust gas recirculation amount control valve is an internal component of the exhaust gas flow rate control valve with respect to the exhaust gas recirculation path. A cooling water passage constituting a part of the cooling water circulation path on the side and the internal component side of the exhaust gas recirculation amount control valve,
An exhaust gas recirculation device, wherein heat transfer fins are provided in the cooling water passage for efficiently transferring heat of the cooling water circulating in the cooling water passage to the housing. The exhaust gas recirculation device according to any one of claims 2 to 15,
An operating state detecting means for detecting an operating state of the internal combustion engine;
Exhaust gas temperature detecting means for detecting the exhaust gas temperature in the exhaust gas recirculation path;
Based on the operating state of the internal combustion engine detected by the operating state detecting means or the exhaust gas temperature detected by the exhaust gas temperature detecting means, the valve opening of the exhaust gas flow rate control valve and the exhaust gas recirculation amount control valve An exhaust gas recirculation device comprising an engine control device for controlling the valve opening degree of the exhaust gas. The exhaust gas recirculation device according to claim 16,
The operating state detecting means has at least a cooling water temperature detecting means for detecting a temperature of the cooling water of the internal combustion engine,
The engine control device
When the temperature of the cooling water of the internal combustion engine detected by the cooling water temperature detecting means is lower than a first predetermined value, the valve opening of the exhaust gas flow rate control valve is set to open the second valve body. Control and
When the temperature of the cooling water of the internal combustion engine detected by the cooling water temperature detecting means is higher than a second predetermined value, the first valve body is opened and the second valve body is closed. An exhaust gas recirculation device that controls a valve opening degree of an exhaust gas flow rate control valve. The exhaust gas recirculation device according to claim 16 or 17,
The operating state detecting means includes at least engine load detecting means for detecting a load state of the internal combustion engine,
The engine control device
The exhaust gas flow ratio adjustment is performed so that the exhaust gas temperature detected by the exhaust gas temperature detecting means substantially matches a target value set corresponding to the load state of the internal combustion engine detected by the engine load detecting means. An exhaust gas recirculation device that performs feedback control of the valve opening degree of a valve.

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