JP2005054778A - Exhaust gas recirculation device for multiple cylinder supercharged engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce NOx in a multiple cylinder supercharged engine due to increase of an EGR ratio in an operation state where a rotary type EGR valve is opened at timing of transmission of peak pressure of exhaust pulsation pressure to set supply boost pressure to be higher than exhaust gas pressure. <P>SOLUTION: An EGR gas inlet 31 to an EGR gas passage 32 is provided in an exhaust pipe 24 between an exhaust manifold collected part 23 of this multiple cylinder supercharged engine 70 and an exhaust gas inlet 26 of a supercharger. A rotary type EGR valve 100 is disposed on the EGR gas passage 32. The rotary type EGR valve 100 is driven to rotate by a crankshaft 51. It is controlled to open at timing when peak pressure of exhaust pulsation pressure is transmitted in engine operation conditions that are varied depending on a rotation phase changeable device 57. The EGR ratio can thus be increased in a wide operation range of the multiple cylinder supercharged engine. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an exhaust gas recirculation device for a multi-cylinder engine equipped with a supercharger.

The exhaust gas discharged from an internal combustion engine such as a diesel engine contains NOx harmful to the human body. As one of the means for reducing NOx exhausted from the engine, exhaust gas recirculation (Exhaust Gas Re) in which a part of the exhaust gas is conventionally taken out from the middle of the exhaust passage and returned to the intake pipe of the engine to mix the intake air. -circulation) (hereinafter referred to as EGR). By mixing EGR gas, which is exhaust gas separated and extracted from the middle of the exhaust passage, into intake air and sucked into the engine as intake air, the inert gas (N ₂ , CO ₂ , H _{2) 2} O) and the like, and the combustion temperature decreases, so that the generation of NOx can be suppressed. In order to perform this EGR smoothly, the pressure in the exhaust passage needs to be higher than the pressure in the intake pipe. Since this condition is satisfied in the non-supercharged engine, EGR is possible in the entire operation region of the engine.
However, under high-load operating conditions of the turbocharged engine, the exhaust gas diverted from the exhaust passage at the inlet of the exhaust turbine is recirculated to the intake pipe of the engine inlet having a high boost pressure downstream of the supply air blower via the EGR pipe. It becomes a state. Under certain engine operating conditions in which the boost boost pressure is higher than the exhaust gas pressure, the exhaust gas may not recirculate to the intake air, and EGR may become impossible. There is a phenomenon that the exhaust pulsation pressure of the exhaust pulsation during engine operation is higher than the supply boost pressure even under specific engine operating conditions in which the supply boost average pressure is higher than the average exhaust gas pressure. EGR is made possible by utilizing this high exhaust pulsation pressure. Patent documents 1, 2, and 3 are known as materials related to this technology.

In the techniques described in Patent Document 1 and Patent Document 2, a reed valve is provided at a connection portion between the EGR gas passage and the intake pipe, and the high pressure exhaust pulsation pressure generated by the exhaust stroke of the engine is higher than the boost pressure. Sometimes, the reed valve is opened by the pressure of the high pressure peak of the exhaust pulsation, so that the exhaust gas is recirculated to the intake air and EGR is performed. As a result, EGR is possible even under specific engine operating conditions in which the intake boost average pressure in the intake pipe is higher than the average exhaust gas pressure in the exhaust gas passage.

In the technique described in Patent Document 3, a rotary valve is provided in each branch pipe portion of an exhaust manifold connected to an exhaust port of each cylinder of a multi-cylinder engine equipped with a turbocharger, and exhaust pulsation occurs in the rotary valve. The valve is periodically opened at the timing, and the exhaust gas having an exhaust pulsation pressure higher than the supply boost pressure is led to the EGR gas passage so that the exhaust gas is recirculated to the intake air. This rotary valve is configured to always rotate by rotational driving from a crankshaft and to open in synchronization with a high pressure peak of exhaust pulsation. As a result, EGR is made possible even under specific engine operating conditions in which the supply boost average pressure is higher than the average exhaust gas pressure.
6-40343 JP-A-9-137754 JP-A-8-338322

However, in the above-mentioned Patent Document 1 and Patent Document 2, the reed valve provided at the connection portion between the EGR gas passage and the intake pipe has a high peak pressure of the exhaust pulsation pressure generated by the exhaust stroke of the engine. The valve is pushed up against the spring force and boost pressure to open, and is closed by the spring force and boost pressure of the reed valve when the exhaust pulsation pressure has a low-pressure waveform. In this way, a part of the energy of the peak pressure with a high exhaust pulsation pressure is consumed because the reed valve is pushed up and opened against the spring force of the reed valve, so the recirculation of the EGR gas is caused by the remaining exhaust pulsation pressure. It will be done by pressure energy. Thus, when the reed valve is used for the EGR valve, the pressure loss of the EGR gas flow becomes large, so that a large amount of exhaust gas is recirculated, and a significant NOx reduction due to an increase in the EGR rate cannot be obtained. It is a problem.

In addition, in order for the reed valve to open and close following the exhaust pulsation and to improve the durability of the reed valve, it is necessary to increase the rigidity of the reed valve body and increase the spring force. Since the pressure loss of the gas flow increases, the EGR rate decreases, and a problem that a sufficient function as the EGR device can be performed occurs.
In addition, since the reed valve that controls the exhaust gas recirculation is disposed at the connection portion of the EGR gas passage and the intake pipe, the exhaust pulsation is attenuated while propagating through the EGR gas passage, and the peak pressure of the exhaust pulsation pressure is high. Decreasing the energy also causes a problem that causes a decrease in the EGR rate.

In the thing of the said patent document 3, the rotary EGR valve which controls the recirculation | reflux of exhaust gas is provided in each of the branch pipe part of the exhaust manifold connected to the exhaust port of each cylinder of a multicylinder engine. In order to recirculate the exhaust gas to the intake air by the peak pressure with a high exhaust pulsation pressure of each cylinder, a rotary EGR valve is provided for each cylinder and opens and closes at a predetermined timing. As described above, in Patent Document 3, since the rotary EGR valve is provided for each cylinder, the same number of rotary EGR valves as the number of cylinders is required. This increases the cost of the engine, which is a problem in practice. Further, since the rotary EGR valve provided for each cylinder needs to be opened and closed at a predetermined timing, it is a component for smoothly driving each rotary EGR valve provided in the branch pipe portion of the exhaust manifold of the engine. Needs to be composed of parts with high rigidity and accuracy, and the structure becomes complicated. Therefore, the thing of the said patent document 3 has a problem which becomes very expensive.

The present invention has been devised in view of the above problems, and has an EGR gas passage for recirculating a part of exhaust gas to intake air and a rotary EGR valve, and exhaust gas discharged from a plurality of cylinders is exhaust manifold. In the multi-cylinder supercharged engine configured to join at the collecting portion and flow into the supercharger, an EGR gas inlet of the EGR gas passage is provided between the exhaust manifold collecting portion and the exhaust gas inlet of the supercharger, A rotary EGR valve is disposed in the vicinity of the EGR gas inlet or in the middle of the EGR gas passage, and the rotary EGR valve is turned on when the peak pressure of the exhaust pulsation pressure of each cylinder propagates to the rotary EGR valve. By opening the valve so that the exhaust gas is recirculated to the intake air, the peak pressure of the exhaust pulsation pressure propagated from a plurality of cylinders is reduced to one rotary EGR. And an object thereof to reflux effectively exhaust gases in compact air by the operation.

In order to achieve the above object, the present invention adopts the following configuration. In other words, the EGR device for a multi-cylinder supercharged engine according to the first aspect of the present invention includes an EGR gas inlet in the EGR gas passage in the exhaust pipe between the exhaust manifold assembly of the multi-cylinder engine and the exhaust gas inlet of the supercharger. A rotary EGR valve is provided in the exhaust pipe or the EGR gas passage, and the peak pressure of the exhaust pulsation pressure generated in the exhaust stroke of the multi-cylinder engine is transmitted to the rotary EGR valve at the timing The rotary EGR valve is opened to recirculate part of the exhaust gas to the intake pipe.

In the first aspect of the present invention, after exhaust gas discharged from a plurality of cylinders of a multi-cylinder supercharged engine is merged at an exhaust manifold collecting section through an exhaust manifold branch pipe connected to an exhaust port of each cylinder, Into the turbocharger. An EGR gas intake port of the EGR gas passage is provided between the exhaust manifold collecting portion and the exhaust gas inlet port of the supercharger, and a rotary EGR valve is provided in the EGR gas passage. Alternatively, a rotary EGR valve is arranged directly in the exhaust pipe between the exhaust manifold collecting portion and the exhaust gas inlet of the supercharger. The exhaust pulsation generated in the exhaust stroke of each cylinder that joins the exhaust gas propagates to the flow of the exhaust gas that joins the exhaust manifold collecting portion, and the EGR gas passage from the EGR gas inlet of the EGR gas passage extends from the exhaust manifold collecting portion. The exhaust pulsation also propagates to the inlet of the rotary EGR valve. A part of the exhaust gas is recirculated to the intake air by opening the rotary EGR valve in synchronism with the timing when the peak pressure with high exhaust pulsation propagates to the inlet of the rotary EGR valve. At this time, the EGR valve is opened during a period when the exhaust pressure at the inlet of the rotary EGR valve is higher than the supply boost pressure, and the exhaust gas required for NOx control of engine combustion is recirculated through the intake pipe. The amount of gas can be secured. The rotary EGR valve is most preferably disposed in the vicinity of the EGR gas inlet, but may be in the middle of the EGR gas passage.

The invention according to claim 2 relates to the EGR device of the multi-cylinder supercharged engine according to claim 1, wherein the rotary EGR valve is composed of a cylindrical case and a cylindrical valve rotatably fitted in the cylindrical case. The cylindrical valve is rotationally driven by a crankshaft of the multi-cylinder engine, a cylindrical case first port is disposed on the cylindrical surface of the cylindrical case, and the cylindrical surface of the cylindrical valve has a rotational periphery of the cylindrical valve. A plurality of cylindrical valve ports penetrating the rotation center space in the direction are disposed, and the cylindrical case is always in communication with the rotation center space of the cylindrical valve at any rotation angle position of the cylinder valve. In the state where the cylindrical case second port is disposed and the cylindrical valve is incorporated in the cylindrical case, the cylindrical case first port and the cylindrical valve port are sequentially engaged by the rotation of the cylindrical valve, and the cylindrical valve is engaged. The cylinder case first port and the cylindrical valve port are arranged so as to communicate with each other, and every time the cylindrical case first port communicates with the rotation center space of the cylindrical valve by the rotation of the cylindrical valve, the rotary When the rotary EGR valve is opened, EGR gas flows out from the cylindrical case second port when the rotary EGR valve opens, and conversely, EGR gas flows out of the cylindrical case. When flowing from the second port, it is a cylindrical valve type rotary EGR valve that flows out from the first port of the cylindrical case.

According to the second aspect of the present invention, the rotary EGR valve is composed of a cylindrical case and a cylindrical valve fitted in a confidential manner so as to be rotatable within the cylindrical case, and the cylindrical valve is driven to rotate by the multi-cylinder engine. Is done. A cylindrical case first port through which EGR gas flows in or out is disposed on the cylindrical surface of the cylindrical case, and a cylinder through which EGR gas flows in or out of any one of the cylindrical end surfaces orthogonal to the cylindrical surface of the cylindrical case. A case second port is provided. Therefore, when the EGR gas inlet of the rotary EGR valve communicates with the cylindrical case first port, the EGR gas outlet of the rotary EGR valve and the cylindrical case second port communicate with each other, and the EGR gas intake of the rotary EGR valve When the inlet communicates with the cylindrical case second port, the EGR gas outlet of the rotary EGR valve and the cylindrical case first port communicate with each other.

In addition, a plurality of cylindrical valve ports penetrating the rotation center space of the cylindrical valve in the circumferential direction of rotation are disposed on the cylindrical surface of the cylindrical valve. In the state where the cylindrical valve is incorporated in the cylindrical case, the cylindrical case second port is configured to always communicate with the rotation center space of the cylindrical valve at any rotational angle position of the cylindrical valve. The cylindrical case first port and the cylindrical valve port are sequentially engaged with each other by rotation so that the cylindrical case first port and the cylindrical valve port communicate with each other. When the cylindrical valve rotates in the cylindrical case, the cylindrical case first port and the cylindrical valve port are engaged, and the cylindrical case first port and the central space of the cylindrical valve communicate with each other. The second port is in a communicating state, and the rotary EGR valve is opened. When the cylindrical valve rotates within the cylindrical case and the engagement between the cylindrical case first port and the cylindrical valve port is deviated, the rotary EGR valve is closed. The rotary EGR valve is opened each time the cylindrical case first port communicates with the rotation center space of the cylindrical valve by the rotation of the cylindrical valve. When the rotary EGR valve is opened, if EGR gas flows in from the cylindrical case first port, it flows out from the cylindrical case second port, and conversely, if EGR gas flows in from the cylindrical case second port, It is structured to flow out from the cylindrical case first port. The number of cylindrical valve ports arranged in the cylindrical valve of the cylindrical valve type rotary EGR valve varies depending on the number of cylinders of the engine, the specifications of the engine cycle, the ratio of the rotational speed of the cylindrical valve to the rotational speed of the crankshaft, and the like.

For example, in the case of a four-cycle four-cylinder engine equipped with one turbocharger, when the rotary EGR valve has one cylindrical case first port and is driven to rotate at half the rotational speed of the crankshaft. Since the exhaust stroke is 4 times during one cycle operation of the engine, a peak pressure with high exhaust pulsation pressure is generated four times. Therefore, the cylindrical valve that rotates once in one cycle has four cylindrical valve ports on the cylindrical surface. Is disposed. Also, for example, a 4-cycle 6-cylinder engine equipped with two turbochargers is divided into two cylinder groups, and the two cylinder groups are ignited at equal intervals, and each of the two cylinder groups has one independent cylinder group. The cylindrical valve type rotary EGR valve is arranged, and each cylindrical valve type rotary EGR valve is provided with a cylindrical valve which is driven to rotate at a half rotation number of one cylindrical case first port and a crankshaft. In addition, when an independent intake, exhaust, and EGR gas flow circuit is provided for each of the two cylinder groups, the exhaust stroke of each cylinder group during one-cycle operation of the engine is three times, so three exhaust pulsations Since a high peak pressure is generated, three cylindrical valve ports are provided on the cylindrical surface of the cylindrical valve that rotates once in one cycle of the engine.

The invention according to claim 3 relates to the rotary EGR valve device of the multi-cylinder supercharged engine according to claim 1, wherein the rotary EGR valve is rotatably fitted in the disc case and the disc case. The disc valve is rotationally driven by the crankshaft of the multi-cylinder engine, and the disc case first port is disposed on one of the circular end surfaces of the disc case and faces the disc. It is configured to have confidentiality with the plate valve, and the other circular end surface of the disc case is provided with a disc case second port and a disc case chamber is provided between the opposing disc valve, The disc case second port and the disc case chamber are always in communication with each other, and a plurality of disc valve ports are arranged in the rotational circumferential direction on the disc surface of the disc valve. When the disc valve is installed, the disc valve rotates. Further, the disc valve port and the disc case first port are arranged to engage with the disc case first port and communicate with each other. The disk case first port is sequentially communicated to open the rotary EGR valve. When the rotary EGR valve is opened, if EGR gas flows from the disk case first port, the disk case When the EGR gas flows out from the second port and conversely flows from the disk case second port, it is a disk valve type rotary EGR valve configured to flow out from the disk case first port. It is characterized by

In this invention, the rotary EGR valve is constituted by a disc case and a disc valve that is rotatably fitted in the disc case, and the disc valve is driven to rotate by the multi-cylinder engine. . A disc case first port is provided on one end face of the disc case and confidentiality is provided between a disc valve facing the disc end face of the disc case provided with the disc case first port. It has a configuration that has. A disc case second port is disposed on the other end surface of the disc case, and a disc case chamber is provided between the disc end surface of the disc case having the disc case second port and the disc valve. The disc case second port and the disc case chamber are always in communication with each other. In addition, a plurality of disc valve ports are provided in the same radial direction of the rotation circumference of the disc valve, and when the disc valve rotates in the disc case, the disc valve port is It arrange | positions in the position which can be engaged with a disk case 1st port. By rotating the disc valve with the disc valve incorporated in the disc case, the disc valve engages with the disc case first port so that the disc valve port communicates with the disc case first port. The plate valve type rotary EGR valve is open. Therefore, the disc valve port and the disc case first port are sequentially communicated by the rotation of the disc valve, and the rotary EGR valve is opened. When the rotary EGR valve is opened, if EGR gas flows from the disk case first port, it flows out from the disk case second port, and conversely if EGR gas flows from the disk case second port, the disk Outflow from the case first port.
The disk case second port may be disposed in a position where communication with the disk case chamber is always possible. The number of disc valve ports arranged on the disc valve of the disc valve type rotary EGR valve varies depending on the number of engine cylinders, engine cycle specifications, the ratio of the rotational speed of the cylindrical valve to the rotational speed of the crankshaft, etc. . For example, in the case of a four-cycle four-cylinder engine equipped with one supercharger, the disc valve type rotary EGR valve has one disc case first port and is at half the rotational speed of the crankshaft. When the engine is driven to rotate, the exhaust stroke is four times during one cycle operation of the engine, so that a high peak pressure of four exhaust pulsation pressures is generated. Four disc valve ports are provided.

A fourth aspect of the present invention relates to a rotary EGR valve device for a multi-cylinder supercharged engine according to any one of the second or third aspects, wherein the crankshaft is changed to the cylindrical valve or the disc valve. A rotation phase variable device capable of changing the rotation phase is disposed in the middle of a rotation driving force transmission circuit for transmitting rotation driving, and a peak pressure with a high exhaust pulsation pressure generated in the exhaust stroke of the multi-cylinder engine is the rotary type. In order to open the rotary EGR valve at the timing of propagation to the EGR valve, the rotational phase variable device changes the engine rotation phase and the rotary EGR valve rotation phase in accordance with the engine operating conditions. The valve opening timing of the rotary EGR valve is advanced or retarded.

In the invention according to claim 4, the timing (crank angle) at which the high peak pressure of the exhaust pulsation pressure of each cylinder is propagated to the cylindrical valve type rotary EGR valve or the disc valve type rotary EGR valve at the sonic speed is the engine operation. In order to change depending on conditions, the cylindrical valve or the disc valve is opened at the timing of the engine crank angle at which the high peak pressure of the exhaust pulsation pressure of the rotary EGR valve consisting of the cylindrical valve or the disc valve has reached. The opening timing of the rotary EGR valve composed of a disc valve needs to be changed according to the operating state of the engine.

In the present invention, a rotational phase variable device capable of changing the rotational phase is disposed between a rotary EGR valve composed of a cylindrical valve or a disc valve and a rotational driving force transmission circuit between the crankshafts to cope with engine operating conditions. By changing the rotation phase of the rotation phase variable device by a predetermined crank angle, the rotary EGR valve composed of a cylindrical valve or a disc valve is an engine in which a peak pressure with a high exhaust pulsation pressure has reached the EGR gas inlet The valve is opened at the timing of the crank angle. The rotational phase of the rotation phase variable device is changed by a predetermined crank angle corresponding to the engine operating conditions, and the EGR gas intake of the rotary EGR valve consisting of a cylindrical valve or a disc valve is changed in all engine operating states of the engine. Since the rotary EGR valve opens at the timing of the engine crank angle at which the peak pressure with high exhaust pulsation pressure reaches the inlet, a large amount of exhaust gas is recirculated to the intake air even when the intake boost pressure is high It is possible to do that.

According to a fifth aspect of the present invention, there is provided an EGR device for a multi-cylinder supercharged engine according to any one of the first to fourth aspects, wherein the EGR gas flows from the exhaust pipe to the intake pipe in the middle of a flow circuit. An EGR gas pressure accumulator is disposed downstream of the EGR gas flow of the rotary EGR valve, an EGR amount adjustment valve is provided downstream of the EGR gas pressure accumulator, and the EGR amount adjustment valve corresponds to an engine operating condition. The opening area is controlled.

In the fifth aspect of the present invention, an EGR amount adjusting valve is newly provided between the rotary EGR valve and the intake pipe, and an EGR gas pressure accumulating chamber is provided between the rotary EGR valve and the EGR amount adjusting valve. It is. Therefore, by opening the rotary EGR valve in synchronism with the timing at which the peak pressure with high exhaust pulsation has propagated to the inlet of the rotary EGR valve, a part of the exhaust gas flows into the EGR gas pressure storage chamber, and the EGR gas pressure storage The chamber pressure increases. By controlling the opening area of the EGR amount adjusting valve in accordance with the engine operating conditions, an EGR gas amount suitable for the engine operating conditions is returned to the intake air.

A sixth aspect of the present invention relates to an EGR device for a multi-cylinder supercharged engine according to any one of the first or fourth aspect, wherein the bypass for bypassing the rotary EGR valve and flowing EGR gas. A bypass shut-off valve is disposed in the middle of the passage and the bypass passage, and the bypass shut-off valve is opened under specific engine operating conditions so that EGR gas can flow through the rotary EGR valve. .

According to the sixth aspect of the present invention, the EGR gas bypass passage extending from the upstream EGR gas passage to the downstream EGR gas passage 33 of the rotary EGR valve and the bypass cutoff valve in the middle of the bypass passage are provided. By opening the bypass cutoff valve, the EGR gas can bypass the rotary EGR valve and recirculate to the intake air. In operating conditions with a low exhaust temperature such as engine partial load, the exhaust gas has low exhaust energy because the exhaust gas temperature and pressure are low, and the charge boost pressure by the exhaust turbocharger does not increase. The average pressure of the exhaust gas is sufficiently lower than the average pressure of the exhaust gas pressure. Therefore, EGR gas can be caused to flow from the exhaust pipe to the intake pipe by opening the bypass passage and the bypass cutoff valve.

As described above, according to the first aspect of the present invention, the exhaust gas is exhausted from the exhaust gas passage between the exhaust manifold assembly portion of the exhaust manifold connected to the exhaust ports of the plurality of cylinders and the upstream of the exhaust gas inlet of the supercharger. An EGR gas intake port of an EGR gas passage for dividing a part of the gas as EGR gas is provided, and a rotary EGR valve is provided in the vicinity of the EGR gas intake port. High peak pressure of exhaust pulsation pressure generated by the exhaust stroke of a plurality of cylinders propagates to one rotary EGR valve, and high peak pressure of high exhaust pulsation pressure of a plurality of cylinders propagates to this rotary EGR valve. The rotary EGR valve is opened at the timing of propagation of the peak pressure. Thus, a plurality of high peak pressures of exhaust pulsation pressure generated by the exhaust strokes of a plurality of cylinders of a multi-cylinder engine are propagated to one rotary EGR valve. In this way, the rotary EGR valve is opened each time a plurality of high peak pulsation pressures of the cylinders propagate to the rotary EGR valve.

Therefore, the rotary EGR valve of the present invention is designed to open a plurality of times at the timing of propagation of the high peak pressure of the exhaust pulsation pressure propagating to the rotary EGR valve during one cycle operation of the multi-cylinder engine. is there. According to the first aspect of the present invention, EGR can be performed by using one rotary EGR valve by using a peak pressure with high exhaust pulsation pressure of a plurality of cylinders. Therefore, the rotary EGR for each cylinder is provided in the exhaust passage for each cylinder. Compared with the case of using a valve, the number of rotary EGR valves is reduced, the structure is simplified, and the cost can be reduced.

Further, when a rotary EGR valve is disposed in the vicinity of the connection position between the EGR gas passage where EGR gas is mixed with intake air and the intake pipe, the peak of exhaust pulsation pressure generated by the exhaust stroke of a plurality of cylinders is high. When the pressure attenuates while propagating through the EGR gas passage and propagates to the rotary EGR valve, the peak pressure of the exhaust pulsation pressure decreases, the EGR rate decreases, and the required NOx reduction cannot be achieved. There is a fear. However, according to the first aspect of the invention, the rotary EGR valve is disposed in the vicinity of the EGR gas inlet of the EGR gas passage for diverting a part of the exhaust gas as EGR gas from the exhaust pipe. Since the peak pressure of the exhaust pulsation pressure propagating to the EGR gas intake port of the rotary EGR valve is prevented from being attenuated, EGR is possible due to the peak pressure of the exhaust pulsation pressure when the rotary EGR valve is opened. Depending on the engine operating conditions, there is an effect that it is possible to sufficiently reduce NOx by increasing the EGR rate even in a relatively high charge boost pressure state.

According to the second aspect of the present invention, the rotary EGR valve is composed of a cylindrical case and a cylindrical valve that is rotatably fitted in the cylindrical case. The rotary EGR valve is opened at the timing when the cylindrical case first port and the cylindrical valve port are engaged and communicated with each other by the rotation of the cylindrical valve. Therefore, it is possible to adjust the rotational phase of the connecting part of the rotating shaft between the cylindrical valve and the crankshaft or the connecting part of the rotating shafts, or adjust the meshing position of the teeth of the rotary drive transmission gear, and rotate it at any crank angle timing. It is possible to open the EGR valve.

In turbocharged engines, there are certain engine operating conditions in which the boost boost pressure is higher than the exhaust gas pressure and the exhaust gas cannot be recirculated to the intake pipe. Under this specific engine operating condition, exhaust pulsation is adjusted by adjusting the rotational phase of the connecting part of the rotating shaft between the cylindrical valve and the crankshaft or the connecting part of the rotating shafts, or by adjusting the meshing position of the teeth of the rotary drive transmission gear. The rotary EGR valve is opened at the timing of the crank angle at which the high peak pressure is propagated from the exhaust valve of each cylinder through the exhaust pipe to the rotary EGR valve. As a result, EGR is enabled under specific engine operating conditions in which the charge boost pressure is higher than the exhaust gas pressure. In the second aspect of the invention, the rotary EGR valve is opened and closed by the rotation of the cylindrical valve driven by the crankshaft. Therefore, the peak pressure energy with high exhaust pulsation pressure is consumed for opening the rotary EGR valve. There is nothing to do. Therefore, there is no loss of energy of peak pressure with high exhaust pulsation pressure because the reed valve is pushed up and opened against the spring force of the reed valve unlike when a reed valve is used for the rotary EGR valve. Since all of the peak pressure energy having a high exhaust pulsation pressure is used for exhaust gas recirculation, a large amount of exhaust gas is recirculated, and a significant NOx reduction due to an increase in the EGR rate can be obtained.

In addition, the rotary EGR valve is operated a plurality of times at the timing when the high peak pressure of the plurality of exhaust pulsation pressures propagated from the plurality of cylinders passes through the exhaust pipe from the exhaust valve of each cylinder and propagates to one rotary EGR valve. Because of the structure for opening the valve, the rotary EGR valve can be made compact. Therefore, it becomes easy to attach to the engine. And since the engine which mounted | wore with the rotary EGR valve to this invention can avoid the large increase in an external dimension, there exists an effect which the mounting to a motor vehicle becomes easy.

According to a third aspect of the present invention, the rotary EGR valve is composed of a disc case and a disc valve that is rotatably fitted in the disc case, and the disc valve is rotated from the crankshaft of the engine. The rotary EGR valve is opened when the disk case first port and the disk valve port are engaged and communicated with each other by the rotation of the disk valve. For this reason, the rotational phase of the connecting part of the rotating shafts of the disc valve and the crankshaft or the connecting part of the rotating shafts or the meshing position of the teeth of the rotary drive transmission gear is adjusted, and the rotary shaft is rotated at any crank angle timing. It is possible to open the EGR valve.

Therefore, in turbocharged engines, the peak boost pressure of exhaust pulsation pressure is exhausted from the exhaust valve of each cylinder under specific operating conditions of the engine where the boost boost pressure is higher than the exhaust gas pressure and the exhaust gas cannot be recirculated to the intake pipe. EGR is made possible by opening the rotary EGR valve at the timing of the crank angle transmitted through the pipe to the rotary EGR valve. Since the rotary EGR valve is opened and closed by the rotation of the disc valve driven by the crankshaft, the peak pressure energy with high exhaust pulsation pressure is not consumed for the rotary EGR valve, and the exhaust gas is recirculated to the intake pipe. It is a structure that is consumed to do. Therefore, a part of the peak pressure energy with high exhaust pulsation pressure is opened because the reed valve is pushed up and opened against the spring force of the reed valve as when the reed valve is used for the rotary EGR valve. Therefore, it is not consumed. Therefore, since peak pressure energy having a high exhaust pulsation pressure is used for exhaust gas recirculation, it is possible to recirculate a large amount of exhaust gas and obtain a significant reduction in NOx due to an increase in the EGR rate.

In addition, at the timing when a plurality of high peak pressures of exhaust pulsation pressure propagated from a plurality of cylinders pass through the exhaust pipe from the exhaust valve of each cylinder to the EGR gas intake port of one rotary EGR valve, Since the valve is opened a plurality of times by rotation, a compact rotary EGR valve can be obtained. Therefore, it becomes easy to attach to the engine. And since the engine which mounted | wore with the rotary EGR valve to this invention can avoid the large increase in an external dimension, there exists an effect which the mounting to a motor vehicle becomes easy.

According to the fourth aspect of the present invention, the cylindrical valve or the disc valve is rotationally driven by the crankshaft, and the rotational phase variable device capable of changing the rotational phase is arranged between the rotational driving force transmission circuits. Set up. Under different engine operating conditions, the timing of the crank angle of the engine at which the peak pressure of the exhaust pulsation pressure reaches the rotary EGR valve composed of a cylindrical valve or a disc valve is different. Therefore, in order to open the cylindrical valve or the disc valve at the timing of the engine crank angle at which the peak pressure of the exhaust pulsation pressure reaches the rotary EGR valve consisting of the cylindrical valve or the disc valve, it consists of the cylindrical valve or the disc valve. The timing of the crank angle of the engine for opening the rotary EGR valve needs to be changed according to the operating state of the engine. For this reason, the rotation phase variable device relatively advances or retards a predetermined crank angle between the rotation phase of the engine and the rotation of the cylindrical valve or the disc valve in accordance with the engine operating condition. This makes it possible to perform EGR using a peak pressure with a high exhaust pulsation pressure in a wide range of the engine operating range, increase the EGR rate in the wide range of the engine operating range, and greatly reduce NOx in the wide range of the engine operating range. There is.

According to the fifth aspect of the present invention, the rotary EGR valve is opened to increase the pressure in the EGR gas accumulator chamber in synchronization with the timing at which the peak pressure with high exhaust pulsation has propagated to the inlet of the rotary EGR valve. By controlling the opening area of the EGR amount regulating valve downstream of the EGR gas flow in the EGR gas accumulating chamber in accordance with the engine operating conditions, the EGR gas amount suitable for the engine operating conditions is returned to the intake air. Therefore, it is possible to achieve an optimum EGR rate in a wide range of the engine operating region, and there is an effect that further NOx can be reduced in a wide range of the engine operating region.

According to the sixth aspect of the present invention, since the average pressure of the boost boost pressure is sufficiently lower than the average pressure of the exhaust gas pressure in the light load operation state of the engine, the rotary EGR valve is not used. However, the EGR gas can be recirculated to the intake air through the bypass passage with the bypass cutoff valve opened. On the other hand, since the peak pressure of the exhaust pulsation is low in the light load operation state of the engine, the EGR gas pressure rise by the rotary EGR valve becomes insufficient, and the rotary pulsation other than the timing at which the peak pressure of the exhaust pulsation propagates Since the EGR valve is closed, the valve opening time is insufficient, and therefore, there is a problem that the EGR gas amount necessary and sufficient for reducing the NOx of the engine cannot be recirculated only by the rotary EGR valve. Therefore, at the light load of the engine, the necessary EGR gas is recirculated to the intake air through the bypass passage with the bypass shutoff valve opened, so that the required EGR rate is obtained in the light load operation state of the engine and sufficient NOx reduction is achieved. There is an effect that can be realized.

A first embodiment of the present invention will be described in detail with reference to FIGS. First, based on FIG. 1, which is a schematic plan view showing a specific configuration of the entire engine system stem when a cylindrical valve type rotary EGR valve is adopted in the four-cylinder supercharged diesel engine of the first embodiment. I will explain.
The engine according to the first embodiment is an in-line four-cylinder four-cycle direct injection supercharged diesel engine for automobiles. Each cylinder of the in-line four-cylinder engine main body 70 is numbered “1” to “4” in order from the cylinder near the cooling fan 71 as shown in the figure, and each of them is designated as “first cylinder” to “fourth”. It will be called "cylinder".

The first cylinder 1 is provided with one electronically controlled fuel injector 81a, two intake valves 10a, two exhaust valves 20a, and one exhaust port 21a. The second cylinder 2 has one electron. The control fuel injector 81b, the two intake valves 10b, the two exhaust valves 20b, and the one exhaust port 21b are provided. The third cylinder 3 has one electronically controlled fuel injector 81c and two intake valves. 10c, two exhaust valves 20c, and one exhaust port 21c are disposed. The fourth cylinder 4 has one electronically controlled fuel injector 81d, two intake valves 10d, two exhaust valves 20d, and 1 A book exhaust port 21d is provided. The in-line cylinder engine body 70 is ignited at equal intervals of 180 degrees (crank angle), and light oil is injected from each electronically controlled fuel injector into each cylinder so that the ignition cylinder order is 1-3-4-2. Is done.

Next, intake and exhaust of the engine and EGR will be described. The intake air taken in from the air cleaner 11 passes through the intake pipe 12 and is pressurized by an air supply blower 41 of a variable capacity turbocharger (hereinafter referred to as VG turbocharger) 40. The pressurized and high-temperature and high-pressure intake air is led to the air-cooled air supply intercooler 14 by the intake pipe 13 and cooled, and the cooled intake air is led to the intake manifold 17 by the intake pipe 15 and the engine main body. The air is sucked into each cylinder via intake valves 10a, 10b, 10c, and 10d of 70 cylinders.

The exhaust gas of each cylinder of the engine main body 70 passes through the exhaust manifold 22 via the exhaust valves 20a, 20b, 20c, 20d and the exhaust ports 21a, 21b, 21c, 21d of each cylinder, and passes through the exhaust pipe 24 and passes through the exhaust pipe 24. Guided to turbocharger 40.

The exhaust gas guided to the VG turbocharger 40 drives the exhaust turbine 42 and rotates the intake blower 41 coaxial with the exhaust turbine 42 to pressurize the intake air taken into the engine body 70. In the VG turbocharger 40, the valve opening degree of the variable exhaust turbine nozzle 43 is adjusted by an electronically controlled variable exhaust turbine nozzle actuator 44 by a signal from an engine ECU (not shown) to control the rotational speed of the exhaust turbine 42. By adjusting the rotational speed of the exhaust turbine 42, the intake boost pressure, which is the pressure of the intake air pressurized by the intake blower 41 driven coaxially with the exhaust turbine 42, is adjusted, and the intake air amount sucked into the engine body 70 Is adjusted.

Next, the exhaust gas flowing out from the exhaust turbine 42 flows into an oxidation catalyst regeneration type particulate matter removing device (Diesel Particulate Filter) (hereinafter referred to as an oxidation catalyst regeneration type DPF device) 28 through an exhaust pipe 27 and exhaust gas. The particulate matter (Particulate Matter) (hereinafter referred to as “PM”) is collected in the oxidation catalyst regeneration type DPF device 28, and the PM in the exhaust gas is purified. Next, the exhaust gas flowing out from the oxidation catalyst regeneration type DPF device 28 flows into the exhaust muffler 29 and then released to the atmosphere.

Further, the exhaust gas of each cylinder of the engine main body 70 is merged at the exhaust manifold collecting portion 23 of the exhaust manifold 22 via the exhaust ports 21a, 21b, 21c, and 21d, but the exhaust manifold collecting portion 23 and the VG turbocharger are combined. An EGR gas inlet 31 of the EGR gas passage is provided between the 40 exhaust gas inlets 26. A cylindrical valve type rotary EGR valve 100 is disposed in the vicinity of the EGR gas inlet 31 of the EGR gas passage 32. By opening the cylindrical valve type rotary EGR valve 100 at a timing when a high peak pressure of exhaust pulsation generated by the exhaust stroke of each cylinder of the engine body 70 propagates to the cylindrical valve type rotary EGR valve 100, a relatively high pressure is achieved. The EGR gas flows into the EGR gas pressure accumulation chamber 34 via the EGR gas passage 33 and is accumulated in the EGR gas pressure accumulation chamber 34.

Further, a pressure sensor 35 is provided in the EGR gas pressure storage chamber 34 to detect the EGR gas pressure storage chamber pressure, and a pressure sensor 16 is provided in the intake pipe 15 to detect the supply air boost pressure. The pressure signal and the charge boost pressure signal are input to the EGR control ECU 80. A control signal for the opening area of the EGR amount adjustment valve 36 is output from the EGR control ECU 80 according to a program stored in advance in the EGR control ECU 80 in response to these input signals and the operating state of the engine. By controlling the opening area, the amount of EGR gas flowing into the EGR cooler 37 is controlled. The EGR gas whose flow rate is adjusted in accordance with the operating state of the engine is cooled by the EGR cooler 37 and then flows into the intake pipe 15 via the EGR gas passage 38.

As a result, the EGR rate is controlled to an optimum value even in an engine operating state in which the average pressure of the supply boost pressure is higher than the average pressure of the exhaust gas pressure, and NOx discharged from the engine can be greatly reduced. In addition, it is possible to return the EGR gas amount optimum for the engine operating state to the intake air even in the engine operating state where the average pressure of the boost boost pressure is higher than the average pressure of the exhaust gas pressure.

Next, the opening and closing of the cylindrical valve type rotary EGR valve 100 will be described. First, the crankshaft gear 51 mounted on the crankshaft 50 rotates the EGR valve drive gear 53 via the idle gear 52. In the transmission of rotation by the combination of gears, the number of teeth of each gear is set so that the EGR valve drive gear 53 rotates at half the number of rotations of the crankshaft 50. The rotation transmitted to the EGR valve drive gear 53 is transmitted to the rotation phase variable device 57 by the rotation transmission shaft 56, and the cylindrical valve 101 of the cylindrical valve type rotary EGR valve 100 rotates from the rotation phase variable device 57 by the rotation transmission shaft 59. Driven. When the cylindrical valve 101 of the cylindrical valve type rotary EGR valve 100 rotates, the cylindrical valve type rotary EGR valve 100 is opened and closed. Here, since the EGR valve drive gear 53 is set to rotate at half the rotational speed of the crankshaft 50, the cylindrical valve 101 driven by the EGR valve drive gear 53 is half the crankshaft 50. The rotation speed is 1.

The rotation phase varying device 57 arranged in the transmission path of the rotational driving force between the EGR valve driving gear 53 and the cylindrical valve 101 changes the rotation phase transmitted to the rotation phase varying device 57 by the rotation transmission shaft 56 and rotates. It is a device that transmits rotation to the transmission shaft 59. Thereby, the phase of rotation of the cylindrical valve 101 coupled to the rotation transmission shaft 59 can be changed, and the opening and closing of the cylindrical valve type rotary EGR valve 100 can be advanced or retarded. Since the timing (crank angle) at which the peak pressure with high exhaust pulsation propagates to the cylindrical valve type rotary EGR valve 100 varies depending on the operating conditions of the engine, the rotational phase variable device 57 opens the cylindrical valve type rotary EGR valve 100. Is changed so that the cylindrical valve-type rotary EGR valve 100 can be opened at the timing (crank angle) at which the peak pressure with high exhaust pulsation is propagated to the cylindrical valve-type rotary EGR valve 100.

Next, the change of the rotation phase transmitted from the rotation transmission shaft 56 to the rotation transmission shaft 59 by the rotation phase varying device 57 will be described. A pulsar 54 is fixedly mounted on the same rotation transmission shaft 56 as the EGR valve drive gear 53 that rotates at half the number of revolutions of the crankshaft 50, and a protrusion on the outer peripheral surface of the pulsar 54 is formed on the outer peripheral surface of the pulsar 54. The EGR valve drive gear rotational speed sensor 55 outputs a detection signal every time it crosses the EGR valve drive gear rotational speed sensor 55 that is mounted to face the projected protrusion, and the EGR valve drive gear rotational speed sensor 55 detects the EGR from the detection signal. The rotation speed and rotation angle of the valve drive gear 53 are detected.

Since the EGR valve drive gear 53 receives the rotational force from the crankshaft gear 51 through a combination of gear mechanisms via the idle gear 52 by the crankshaft gear 51, the rotation speed of the crankshaft is detected from the detection signal of the EGR valve drive gear rotation speed sensor 55. And the rotation angle is detected. Similarly to the detection of the rotational speed of the EGR valve drive gear 53, the protrusion of the pulsar 58 crosses the EGR valve rotational speed sensor 60 mounted facing the protrusion on the outer peripheral surface of the pulsar 58 disposed on the rotation transmission shaft 59. The EGR valve rotation speed sensor 60 outputs a detection signal every time, and the rotation speed and rotation angle of the cylindrical valve 101 are detected from the detection signal of the EGR valve rotation speed sensor 54. Further, the pressure sensor 25 disposed in the EGR gas passage 32 detects a high peak pressure of exhaust pulsation propagated through the cylindrical valve type rotary EGR valve 100.

High peak pressure of exhaust pulsation propagated to the cylindrical valve type rotary EGR valve 100 detected by the pressure sensor 25, crank shaft rotation angle detected by the EGR valve drive gear rotation speed sensor 55, detection by the EGR valve rotation speed sensor 60 The engine operating state signal such as the rotation angle of the cylindrical valve 101 and the engine load (not shown) is input to an EGR control ECU (Electronic Control Unit) 80. Based on these input signals, the EGR control ECU 80 opens the cylindrical valve-type rotary EGR valve 100 at the timing (crank angle) at which the peak pressure with high exhaust pulsation propagated to the cylindrical valve-type rotary EGR valve 100 is detected. Then, a signal for changing the rotation phase is output to the rotation phase varying device 57 to change the rotation phase of the cylindrical valve 101.

Thus, the EGR control ECU 80 outputs a signal for changing the rotation phase from the rotation phase varying device 57 to change the rotation phase of the cylindrical valve 101, and the cylindrical valve type rotary EGR valve 100 has a peak pressure with high exhaust pulsation. The cylindrical valve-type rotary EGR valve 100 is opened at the timing (crank angle) at which is propagated.

Alternatively, a map of the timing (crank angle) of high peak pressure of exhaust pulsation propagating to the cylindrical valve type rotary EGR valve 100 corresponding to the operating condition of the engine is stored in the EGR control ECU 80 in advance, and the cylindrical valve type rotary The EGR control ECU 80 may change the rotation phase from the rotation phase variable device 57 so that the expression EGR valve 100 opens at a timing (crank angle) corresponding to the operating condition of the engine.

Further, a pressure sensor 35 is disposed in the EGR gas accumulating chamber 34 to detect the EGR gas accumulating chamber pressure, and a pressure sensor 16 is disposed in the intake pipe 15 to detect the supply air boost pressure, and each EGR gas accumulating pressure is detected. The chamber pressure signal and the charge boost pressure signal are input to the EGR control ECU 80, and the EGR control ECU 70 opens the EGR amount adjusting valve 36 in accordance with the operating state of the engine as preprogrammed and stored in the EGR control ECU 80. An area control signal is output to control the opening of the EGR amount adjusting valve 36, and a high-pressure EGR gas is caused to flow into the intake pipe 15 via the EGR gas passage 38 so that the average pressure of the supply boost pressure becomes the exhaust gas. Control to achieve an EGR rate that is optimal for engine operating conditions higher than the average pressure so that NOx emitted from the engine can be significantly reduced. It was.

Next, the structure of the cylindrical valve type rotary EGR valve 100 will be described with reference to FIG. 2 which is a schematic drawing showing a specific configuration. In the cylindrical valve type rotary EGR valve 100, a cylindrical valve 101 is rotatably fitted in an internal space of a cylindrical case constituted by a cylindrical case body 110 and a cylindrical case cover 113. The cylindrical valve 101 is rotated by the rotation transmission shaft 59 at a rotational speed that is a half of the crankshaft of the engine. Since the cylindrical valve cylinder end surface 104 of the cylindrical valve 101 facing the cylindrical case cover 113 is open, the cylindrical case second port 112 disposed in the cylindrical case cover 113 is always set regardless of the rotational position of the cylindrical valve 101. The cylindrical case second port 112 and the rotation center space 103 are in communication with each other. Since the cylindrical case second port 112 is connected to the EGR gas passage 32, the exhaust gas from the EGR gas passage 32 always flows into the rotation center space 103.

Since the engine according to the first embodiment is a four-cycle direct-injection supercharged diesel engine with in-line four-cylinder ignition for automobiles, the engine body 70 has four rotations of the crankshaft 50 in one cycle. A high peak pressure with four exhaust pulsations is generated in the exhaust stroke. Therefore, the cylindrical valve type rotary EGR valve 100 needs to be opened four times in one cycle of the engine. Since the cylindrical valve 101 has a structure that rotates at half the rotational speed of the crankshaft, a total of four cylindrical valve ports 102 are provided on the cylindrical surface of the cylindrical valve 101 at 90 ° intervals in the circumferential direction of the cylindrical valve 101. It is arranged. One cylindrical case first port 111 is disposed on the cylindrical surface of the cylindrical case main body 110. When the cylindrical valve 101 rotates, the four cylindrical valve ports 102 of the cylindrical valve 101 sequentially turn into the cylindrical case first port. 111 is a structure that engages with and communicates with 111. In this way, the cylindrical case first port 111 and the cylindrical valve port 102 are arranged so that the cylindrical valve port 102 and the cylindrical case first port 111 communicate with each other four times per rotation of the cylindrical valve 101. The cylindrical case first port 111 is connected to the EGR gas passage 33.

Therefore, the high peak pressure of the exhaust pulsation propagated to the EGR gas intake 31 of the EGR gas passage 32 is propagated to the rotation center space 103 through the EGR gas passage 32 and the cylindrical case second port 112. The cylindrical valve port 102 and the cylindrical case first port 111 are communicated with each other at a timing (crank angle) at which a peak pressure with high exhaust pulsation has propagated to the rotation center space 103 so that high-pressure EGR gas flows into the EGR gas passage 33. To.

As described above, in the engine according to the first embodiment, the timing at which the peak pressure with high exhaust pulsation propagates to the cylindrical valve type rotary EGR valve 100 depending on the engine operating state such as the engine speed and the engine load (crank Since the opening and closing of the cylindrical valve type rotary EGR valve 100 is controlled by the driving force of the crankshaft 50 at an angle), the engine operation is such that the average pressure of the boost boost pressure is higher than the average pressure of the exhaust gas pressure. In the state, it is possible to make the pressure of the EGR gas accumulator 34 sufficiently high by effectively utilizing the peak pressure energy with high exhaust pulsation.

By controlling the opening of the cylindrical valve type rotary EGR valve 100, the pressure in the EGR gas accumulating chamber 34 is sufficiently increased, the EGR rate of the engine body 70 can be improved, and discharged from the engine body 70. There is an effect that NOx can be greatly reduced. Further, an EGR amount adjusting valve 36 is disposed between the EGR gas accumulating chamber 34 and the intake pipe 15, and the opening area of the EGR amount adjusting valve 36 corresponding to the operating state of the engine body 70 is controlled by the EGR control ECU 70. Since it can be controlled to an accurate EGR rate that is optimal for engine combustion, NOx generation due to engine combustion can be suppressed, and as a result, an extremely low NOx emission level can be achieved.

Next, a detailed description will be given based on FIGS. 3 to 4 according to the second embodiment of the present invention. FIG. 3 is a schematic plan view showing a specific configuration of the entire engine system stem when a disc valve type rotary EGR valve is adopted in the four-cylinder supercharged diesel engine in the second embodiment. explain. In this figure, the same reference numerals are given to the same elements shown in FIGS. 1 and 2 according to the first embodiment.

In the second embodiment, the cylindrical valve type rotary EGR valve 100 according to the first embodiment of the present invention is replaced with a disk type rotary EGR valve 200, and an EGR bypass valve 220 and an EGR control ECU 80 newly provide an EGR bypass. The electronic control of the valve 220 is added, and the rotary EGR valve bypass passage is added. Other than these, the second embodiment is the same as the first embodiment. The engine main body 70 is an in-line four-cylinder four-cycle direct-injection supercharged diesel engine for automobiles, and the same applies to the intake system and the exhaust system. The structure of 200, its drive system, the flow of EGR gas and its control, etc. will be described focusing on the EGR system.

First, the opening and closing of the disc type rotary EGR valve 200 will be described with reference to FIG. A crankshaft gear 51 mounted on the crankshaft 50 is rotationally driven by an EGR valve drive gear 53 via an idle gear 52. In the transmission of rotation by the combination of gears, the number of teeth of each gear is set so that the EGR valve drive gear 53 rotates at half the number of rotations of the crankshaft 50. The rotation transmitted to the EGR valve drive gear 53 is transmitted to the rotation phase variable device 57 by the rotation transmission shaft 56, and the cylindrical valve 201 of the disc type rotary EGR valve 200 is rotated from the rotation phase variable device 57 by the rotation transmission shaft 59. Driven. By rotating the disc valve 201 of the disc valve type rotary EGR valve 200, the disc valve type rotary EGR valve 200 is opened and closed. Here, since the EGR valve drive gear 53 is set to rotate at half the rotational speed of the crankshaft 50, the disc valve 201 driven by the EGR valve drive gear 53 is half the crankshaft 50. Is rotated at a rotation speed of 1.

A rotational phase varying device 57 disposed in the transmission path of the rotational driving force between the EGR valve driving gear 53 and the disc valve 201 determines the phase of rotation transmitted from the rotational transmission shaft 56 to the rotational transmission shaft 59. It is a device to change by the signal from. As a result, the phase of rotation of the disc valve 201 coupled to the rotation transmission shaft 59 is changed so that the opening and closing of the disc valve type rotary EGR valve 200 can be advanced or retarded.

Under different operating conditions of the engine body 70, the wing (crank angle) at which the peak pressure with high exhaust pulsation propagates to the disc valve type rotary EGR valve 200 changes. Therefore, by making it possible to change the valve opening timing of the disc valve type rotary EGR valve 200 by the rotation phase variable device 57 corresponding to the operating conditions of the engine main body 70, it is possible to change the circle for all engine operating conditions. The disc valve type rotary EGR valve 200 can be opened at the timing (crank angle) at which the peak pressure with high exhaust pulsation propagates to the plate valve type rotary EGR valve 200.

Next, the structure of the disc valve type rotary EGR valve 200 will be described with reference to FIG. 4 which is a schematic drawing showing a specific configuration. In the disc valve type rotary EGR valve 200, the disc valve 201 is rotatably fitted in the internal space of the disc case constituted by the disc case body 210 and the disc case cover 213. Then, the disc valve 201 is rotated by the rotation transmission shaft 59 at a rotational speed that is half that of the crankshaft of the engine. The disc case cover 213 is provided with one disc case second port 212, one connected to the EGR gas passage 32 and the other opened to the disc case chamber 203. Since the EGR gas passage 32 is always in communication with the disc case chamber 203, exhaust gas always flows into the disc case chamber 203 from the EGR gas passage 32.

The disc valve 201 is provided with a disc valve port 202 penetrating the disc in the rotational circumferential direction of the disc surface. The disc case main body 210 is provided with one disc case first port 211 having one end connected to the EGR gas passage 33 and the other end engaged with and communicated with the disc valve port 202 of the disc valve 201. It is installed. The disc valve 201 is structured such that the disc valve port 202 and the disc case first port 211 are engaged when the disc valve 201 is rotated. Thus, during the period in which the disc valve port 202 and the disc case first port 211 are engaged and communicated, the exhaust gas in the disc case chamber 203 is used as EGR gas as the disc valve port 202 and the disc case first. The disc valve type rotary EGR valve 200 that flows through the port 211 and flows into the EGR gas passage 33 is opened.

Since the engine of the second embodiment is a four-cycle direct-injection supercharged diesel engine with in-line four-cylinder ignition for automobiles, the crankshaft 50 makes two revolutions to generate a high peak pressure with four exhaust pulsations. . The disc valve type rotary EGR valve 200 needs to be opened at the timing when the high peak pressure of the exhaust pulsation generated four times by the crankshaft 50 every two rotations propagates to the disc valve type rotary EGR valve 200. is there.

On the other hand, the disc valve 201 of the disc valve type rotary EGR valve 200 has a structure that rotates at half the rotational speed of the crankshaft. A total of four disc valve ports 202 were arranged at intervals of 90 ° in the rotational circumferential direction. As a result, the disc valve 201 makes one rotation, so that the four disc valve ports 202 of the disc valve 201 are sequentially engaged with the disc case first port 211 and the disc case chamber 203 and the disc case. The disc valve type rotary EGR valve 200 communicated with the first port 211 is opened, and the exhaust gas in the disc case chamber 203 passes through the disc valve port 202 and the disc case first port 211 as EGR gas. Then, it can be discharged to the EGR gas passage 33. That is, the disc valve type rotary EGR valve 200 has a structure in which the disc valve 201 is opened four times by one rotation of the disc valve 201.

In the engine of the second embodiment, a high peak pressure of four exhaust pulsations generated by the exhaust stroke of each cylinder of the engine body 70 is generated every two rotations of the crankshaft 50. The expression EGR valve 200 rotates once to open four times. In this case, the valve opening timing is changed under the control of the rotation phase variable device 57 corresponding to the operating state of the engine, and the timing (crank angle) at which the peak pressure with high exhaust pulsation is propagated to the disc valve type rotary EGR valve 200 Thus, the disc valve type rotary EGR valve 200 is opened.

By opening the disc valve type rotary EGR valve 200 at the timing (crank angle) at which the peak pressure with high exhaust pulsation has propagated to the disc valve type rotary EGR valve 200 in this way, a relatively high pressure EGR gas is obtained. Is caused to flow into the EGR gas pressure accumulation chamber 34 via the EGR gas passage 33 to increase the pressure in the EGR gas pressure accumulation chamber 34.

Further, a pressure sensor 35 is provided in the EGR gas accumulator 34 to detect the EGR gas accumulator pressure, and a pressure sensor 16 is provided to the intake pipe 15 to detect the supply air boost pressure. An EGR gas accumulator pressure signal and a charge boost pressure signal are input. A control signal for the opening area of the EGR amount adjustment valve 36 is output from the EGR control ECU 80 according to a program stored in advance in the EGR control ECU 80 in response to these input signals and the operating state of the engine. By controlling the opening area, the amount of EGR gas flowing into the EGR cooler 37 is controlled.

The EGR gas whose flow rate is adjusted according to the operating state of the engine is cooled by the EGR cooler 37 and then flows into the intake pipe 15 via the EGR gas passage 38. This makes it possible to control to an optimum EGR rate in an engine operating state in which the average pressure of the boost boost pressure is higher than the average pressure of the exhaust gas pressure, so that the effect of greatly reducing NOx exhausted from the engine can be obtained. .

Further, in order to allow the EGR gas to flow by bypassing the disc valve type rotary EGR valve 200, the bypass passage 90 for diverting the EGR gas from the EGR gas passage 32 to the EGR gas passage 33, and the bypass cutoff valve 220. In addition, a bypass circuit composed of the bypass passage 91 is provided. Then, in an engine operating state where the average pressure of the boost boost pressure is sufficiently lower than the average pressure of the exhaust gas pressure, the EGR control ECU 80 outputs a control signal to the bypass cutoff valve 220 to open the bypass cutoff valve 220. The EGR gas is caused to flow from the EGR gas passage 32 to the EGR gas passage 33 by bypassing the disc valve type rotary EGR valve 200.

Then, in an engine operating state where the average pressure of the supply boost pressure is sufficiently lower than the average pressure of the exhaust gas pressure, the bypass shutoff valve 220 is opened to increase the pressure in the EGR gas pressure accumulating chamber 34. To do. As a result, a circuit that allows the EGR gas to pass through the bypass flow circuit from the bypass passage 90 to the bypass passage 91 in an engine operating state where the average pressure of the charge boost pressure is sufficiently lower than the average pressure of the exhaust gas pressure is added. Thus, the EGR gas flow pressure loss is reduced, and the EGR rate can be improved as compared with the case where the EGR gas is a single EGR circuit that passes through the disc valve type rotary EGR valve 200. . However, even when the EGR gas passes through the bypass flow circuit, in order to accurately control the EGR rate, the EGR control ECU 80 outputs a control signal of the opening area of the EGR amount adjusting valve 36 to output the EGR amount adjusting valve 36. The valve opening is controlled.

As mentioned above, although 1st Embodiment and 2nd Embodiment of this invention were explained in full detail with drawing, a concrete structure is not restricted to these forms, The design of the range which does not deviate from the summary of this invention Any changes and the like are included in the scope of the present invention. That is, the engine body 70 is an in-line four-cylinder four-cycle direct-injection supercharged diesel engine for automobiles, but it can also be applied to other engines. For example, it may be other than for automobiles. Further, although an in-line four-cylinder four-cycle direct-injection supercharged diesel engine is used, an in-line six-cylinder four-cycle direct-injection supercharged diesel engine or an in-line six-cylinder four-cycle liquid fuel pilot injection self-ignition natural gas engine may be used. Further, an engine having 6 or more cylinders may be used.

In the first embodiment, the cylindrical valve type rotary EGR valve 100 is used, and the disc valve type rotary EGR valve 200 of the second embodiment is used. The rotary EGR valve of the present invention is not limited to a cylindrical valve type or a disc valve type. For example, as in the first embodiment, a plurality of ports may be rotated in a circumferential direction on a conical surface that rotates in a conical case as in the case of rotating the cylindrical valve 101 in the cylindrical case. good.
The cylinder valve 101 of the cylindrical valve type rotary EGR valve 100 of the first embodiment and the disc valve 201 of the disc valve type rotary EGR valve 200 of the second embodiment have the same rotational speed as the crankshaft 51. In the case of rotational driving, a total of two cylindrical valve ports 102 of the cylindrical valve 101 are arranged at intervals of 180 ° in the rotational circumferential direction, and the disc valve port 202 of the disc valve 201 is 180 in the rotational circumferential direction. Two in total are arranged at intervals of °.
Further, the EGR gas accumulating chamber 34 of the first embodiment and the second embodiment is not specially arranged, and EGR gas may be accumulated in the EGR gas passage 33. In that case, a pressure sensor 35 is disposed in the EGR gas passage 33 in order to detect the EGR gas pressure accumulated in the EGR gas passage 33.

In addition, a cylinder valve of a cylindrical valve type rotary EGR valve and a disc valve of a disc valve type rotary EGR valve in an in-line six-cylinder equidistant ignition four-cycle supercharged engine have a rotational speed that is half the crankshaft. In the case of rotational driving, a total of six cylindrical valve ports of the cylindrical valve are arranged at intervals of 60 ° in the circumferential direction of the rotation, and the disc valve ports of the disk valve are totaled at intervals of 60 ° in the circumferential direction of rotation. Six are arranged.
In addition, the cylinder valve of the cylindrical valve type rotary EGR valve and the disc valve of the disc valve type rotary EGR valve are driven to rotate at the same rotational speed as the crankshaft in an in-line six-cylinder equidistant ignition four-cycle supercharged engine. In this case, a total of three cylindrical valve ports of the cylindrical valve are arranged at intervals of 120 ° in the rotation circumferential direction, and a total of three circular valve ports of the disk valve are arranged at intervals of 120 ° in the rotation circumferential direction. Arranged.

Further, when the lengths of the exhaust passages of each cylinder of the multi-cylinder engine and the cylindrical valve type rotary EGR valve or the disc valve type rotary EGR valve are greatly different from each other, there is a tang that propagates a high peak pressure of exhaust pulsation of each cylinder ( It is not necessary to change the intervals at which the plurality of ports of the cylindrical valve port or the disc valve port are arranged so that the valves can be opened at a crank angle).

FIG. 3 is a schematic plan view showing a specific configuration of the entire engine system stem when a cylindrical valve type rotary EGR valve is employed in the four-cylinder supercharged diesel engine in the first embodiment. 2 is a schematic drawing showing a specific configuration of a cylindrical valve type rotary EGR valve in the four-cylinder supercharged diesel engine of the first embodiment. It is a typical top view which shows a concrete structure about the whole stem of an engine system at the time of employ | adopting a disc valve type rotary EGR valve for the 4-cylinder supercharged diesel engine in this 2nd Embodiment. 2 is a schematic drawing showing a specific configuration of a disc valve type rotary EGR valve for a four-cylinder supercharged diesel engine according to the first embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st cylinder 2 2nd cylinder 3 3rd cylinder 4 4th cylinder 10a, 10b, 10c, 10d Intake valve 11 Air cleaner 12, 13 Intake pipe 14 Air-cooling type supply intercooler 15 Intake pipe 16 Pressure sensor
17 Intake manifolds 20a, 20b, 20c, 20d Exhaust valves 21a, 21b, 21c, 21d Exhaust port 22 Exhaust manifold 23 Exhaust manifold assembly 24 Exhaust pipe 25 Pressure sensor 26 Exhaust gas inlet 27 Exhaust pipe 28 Oxidation catalyst regeneration type DPF device 29 Exhaust muffler 31 EGR gas intake 32, 33 EGR gas passage 34 EGR gas accumulator chamber 35 Pressure sensor 36 EGR amount adjustment valve 37 EGR cooler 38 EGR gas passage 40 VG turbocharger 41 Supply blower 42 Exhaust turbine 43 Variable exhaust turbine Nozzle 44 Electronically controlled variable exhaust turbine nozzle actuator 50 Crankshaft 51 Crankshaft gear 52 Idle gear 53 EGR valve drive gear 54 Pulsar 55 EGR valve drive gear rotational speed sensor 56 Rotation transmission shaft 57 Rotation phase variable device 58 Pulsar 59 Rotation transmission shaft 60 EGR valve rotation speed sensor 70 Engine body 71 Cooling fan 80 EGR control ECU
81a, 81b, 81c, 81d Electronically controlled fuel injector 90, 91 bypass passage 100 Cylindrical valve type rotary EGR valve 101 Cylindrical valve 102 Cylindrical valve port 103 Rotation center space part 104 Cylindrical valve cylindrical end face 110 Cylindrical case main body 111 Cylindrical case first Port 112 Cylindrical case second port 113 Cylindrical case cover 200 Disc valve type rotary EGR valve 201 Disc valve 202 Disc valve port 203 Disc case chamber 210 Disc case body 211 Disc case first port 212 Disc case 2nd port 213 Disc case cover 220 Bypass shutoff valve

Claims (6)

An EGR gas inlet for the EGR gas passage is provided in the exhaust pipe between the exhaust manifold collecting portion of the multi-cylinder engine and the exhaust gas inlet of the supercharger, and a rotary EGR valve is provided in the exhaust pipe or the EGR gas passage. The rotary EGR valve is opened at a timing when a high peak pressure of the exhaust pulsation pressure generated in the exhaust stroke of the multi-cylinder engine propagates to the rotary EGR valve, and a part of the exhaust gas is recirculated to the intake pipe. EGR device for multi-cylinder supercharged engine The rotary EGR valve is composed of a cylindrical case and a cylindrical valve rotatably fitted in the cylindrical case, and the cylindrical valve is rotationally driven by a crankshaft of the multi-cylinder engine, and the cylindrical surface of the cylindrical case A cylindrical case first port is disposed, and a plurality of cylindrical valve ports penetrating the rotation center space in the rotational circumferential direction of the cylindrical valve are disposed on the cylindrical surface of the cylindrical valve. A cylindrical case second port is provided so as to always communicate with the rotation center space of the cylindrical valve at any rotational angle position of the cylindrical valve, and the cylindrical valve is in the state where the cylindrical valve is incorporated in the cylindrical case. The cylindrical case first port and the cylindrical valve port are sequentially engaged by rotation of the valve so that the cylindrical case first port and the cylindrical valve port communicate with each other. The rotary EGR valve is opened each time the first port of the cylindrical case communicates with the rotation center space of the cylindrical valve by the rotation of the valve. When the rotary EGR valve is opened, EGR gas is removed from the cylindrical case. A cylindrical valve-type rotary that flows out from the cylindrical case second port when flowing from the first port, and conversely when EGR gas flows from the cylindrical case second port, flows out from the cylindrical case first port. 2. The EGR device for a multi-cylinder supercharged engine according to claim 1, wherein the EGR device is an EGR valve. The rotary EGR valve is composed of a disc case and a disc valve rotatably fitted in the disc case, and the disc valve is rotationally driven by a crankshaft of the multi-cylinder engine. A disk case first port is disposed on one circular end surface of the plate case and has a confidentiality with the disk valve facing the disk case, and the other circular end surface of the disk case is the disk case second. A disk case chamber is provided between the disk valve facing and facing the disk valve, and the disk case second port and the disk case chamber are always in communication with each other. A plurality of disc valve ports are arranged on the surface in the circumferential direction of rotation, and when the disc valve is incorporated in the disc case, the disc valve is engaged with the disc case first port by the rotation of the disc valve. The disc valve port communicates with the disc case first port. When the disc valve rotates, the disc valve port and the disc case first port sequentially communicate with each other to open the rotary EGR valve, and the rotary EGR valve When EGR gas flows in from the disk case first port when the valve is opened, it flows out of the disk case second port, and conversely, if EGR gas flows in from the disk case second port, the disk case 2. The EGR device for a multi-cylinder supercharged engine according to claim 1, wherein the EGR device is a disc valve type rotary EGR valve that flows out from the first port. A rotational phase variable device capable of changing the rotational phase is disposed in the middle of a rotational driving force transmission circuit for transmitting rotational driving from the crankshaft to the cylindrical valve or the disc valve, and in the exhaust stroke of the multi-cylinder engine. The rotational phase variable device adjusts the phase of the engine rotation so that the rotary EGR valve is opened at the timing when the generated peak pressure of the exhaust pulsation pressure propagates to the rotary EGR valve. 4. The multi-cylinder overload according to claim 1, wherein a phase of rotation of the rotary EGR valve is changed to advance or retard the valve opening timing of the rotary EGR valve. 5. EGR device for feed engine. In the middle of the EGR gas flow circuit that recirculates from the exhaust pipe to the intake pipe, an EGR gas pressure accumulator is disposed downstream of the EGR gas flow of the rotary EGR valve, and an EGR amount downstream of the EGR gas pressure accumulator. The EGR device for a multi-cylinder supercharged engine according to any one of claims 1 to 4, wherein a control valve is provided, and an opening area of the EGR amount control valve is controlled in accordance with an engine operating condition. . A bypass passage for bypassing the rotary EGR valve and flowing EGR gas and a bypass cutoff valve in the middle of the bypass passage are opened, and the bypass cutoff valve is opened under specific engine operating conditions. The EGR device for a multi-cylinder supercharged engine according to any one of claims 1 to 5, wherein the rotary EGR valve can be bypassed to flow.

Images