JP2009047138A - Internal combustion engine - Google Patents

Abstract

An internal combustion engine capable of reliably preventing overheating and maintaining catalyst purification performance is provided.
A cooling medium independent of an exhaust gas introduction part cooling means 71 capable of cooling an exhaust gas introduction part 60 for introducing exhaust gas into a supercharging means 5 by a cooling medium and a cooling system for cooling an internal combustion engine body 2 is provided. The cooling medium passage 72 can be circulated to the exhaust gas introduction portion cooling means 71, the radiator 73 can be cooled the cooling medium circulated through the cooling medium passage 72, and the flow rate of the cooling medium supplied to the exhaust gas introduction portion cooling means 71 The supercharging means cooling system 70 having a flow rate adjusting means 74 capable of adjusting the exhaust gas, the exhaust gas temperature detecting means 94 for detecting the temperature of the exhaust gas introduced into the catalyst 10b, and the exhaust gas detected by the exhaust gas temperature detecting means 94. And a control means 90 for controlling the flow rate adjusting means 74 based on the temperature of the gas.
[Selection] Figure 1

Description

  The present invention relates to an internal combustion engine, and more particularly to an internal combustion engine including a supercharger that compresses and supercharges intake air.

  Generally, in an internal combustion engine for automobiles, it is preferable to increase the amount of air charged into a combustion chamber in order to improve the output. Therefore, conventionally, not only air is sucked into the combustion chamber by the negative pressure generated in the combustion chamber as the piston moves, but also the compressor is driven by the exhaust turbine driven by the energy of the exhaust gas, and the intake air is supplied to the internal combustion engine. A supercharger has been proposed and put into practical use in which air is forcibly fed into a combustion chamber by supercharging, that is, compressed and supplied, and the efficiency of charging the air into the combustion chamber is increased. In recent years, in order to realize downsizing of an internal combustion engine, there is one that realizes further increase in output of the internal combustion engine by setting the supercharging pressure by the supercharger as described above to be high. It achieves a substantial large displacement despite the displacement.

Then, in the internal combustion engine in which the efficiency of charging the air into the combustion chamber is increased in this way, for example, the exhaust air ratio (over the entire operating range is required due to exhaust gas purification (NOx reduction) and fuel efficiency improvement (CO ₂ reduction). Excess air ratio λ = actual air / fuel ratio / theoretical air / fuel ratio, if λ> 1, the air / fuel ratio is on the lean side, whereas if λ <1, the air / fuel ratio is on the rich side) = 1 When operating at (theoretical air-fuel ratio), the exhaust gas temperature discharged from the combustion chamber tends to be relatively high. For this reason, in such an internal combustion engine, it is necessary to increase the heat resistance of an exhaust gas introduction section such as an exhaust manifold or a turbine housing that introduces exhaust gas into the supercharger in order to prevent overheating. On the other hand, when a high heat-resistant material is frequently used in the exhaust gas introduction part, there is an influence of the recent increase in material cost, which may result in an increase in cost.

  For this reason, the conventional internal combustion engine is provided with a jacket portion so as to cover an exhaust gas introduction portion such as an exhaust manifold or a turbine housing that is heated by exhaust gas, and a cooling medium, for example, cooling water is supplied to the jacket portion. There are some which cool the exhaust gas introduction part. For example, a temperature control device for a catalytic converter described in Patent Document 1 serves as a cooling system for cooling an exhaust manifold, and closes a water jacket covering the exhaust manifold and a cooling water circulation passage of the water jacket when the engine is cold. The on-off valve device is configured to open after the engine is warmed up, and the reservoir tank passage that discharges the cooling water in the water jacket when the engine is cold. As a result, the exhaust manifold cooling system provided in the temperature control device of the catalytic converter improves the warming-up performance of the catalytic converter when the engine is cold, and prevents overheating of the exhaust manifold and the catalytic converter after the engine is warmed up. Yes.

Japanese Patent Laid-Open No. 3-179122

  However, in the exhaust manifold cooling system provided in the temperature control device for the catalytic converter described in Patent Document 1 described above, for example, the exhaust manifold is cooled too much in an operation region after the engine is warmed up and the heat load is low. As a result, the exhaust gas temperature is excessively lowered, and the catalyst bed temperature of the catalytic converter may be lower than a predetermined activation temperature, which may reduce the purification performance of the catalytic converter. There is.

  Accordingly, an object of the present invention is to provide an internal combustion engine that can reliably prevent overheating and maintain catalyst purification performance.

  In order to achieve the above object, an internal combustion engine according to a first aspect of the present invention is configured to exhaust gas from an internal combustion engine body and to have an exhaust passage having a catalyst for purifying the exhaust gas, and an exhaust gas introduction unit. Supercharging means for compressing and supercharging the intake air to the internal combustion engine body by being driven by the introduced exhaust gas, and exhaust gas introduction part cooling means capable of cooling the exhaust gas introduction part with a cooling medium; A cooling medium passage capable of circulating the cooling medium to the exhaust gas introduction part cooling means independently of a cooling system for cooling the internal combustion engine body; and a radiator capable of cooling the cooling medium circulating in the cooling medium passage; A supercharging means cooling system having a flow rate adjusting means capable of adjusting a flow rate of the cooling medium supplied to the exhaust gas introducing section cooling means, and detecting a temperature of the exhaust gas introduced into the catalyst. An exhaust gas temperature detection means, and a controlling means for controlling the flow rate adjusting means based on the temperature of the exhaust gases the exhaust gas temperature detecting means has detected.

  In the internal combustion engine according to claim 2, the exhaust passage has an exhaust introduction passage for introducing the exhaust gas into the supercharging means, and the supercharging means is an exhaust gas introduced from the exhaust introduction passage. A turbine in which a wheel that is rotationally driven by the turbine housing is housed in a turbine housing, and a compressor in which an impeller that rotates when the wheel is rotationally driven is housed in the compressor housing, and the exhaust gas introduction portion includes the exhaust gas introduction passage. And the turbine housing, wherein the exhaust gas introduction part cooling means is provided in at least one of the exhaust introduction passage and the turbine housing.

  In the internal combustion engine according to the third aspect of the invention, the catalyst includes a first catalyst and a second catalyst provided downstream of the first catalyst with respect to the exhaust direction of the exhaust gas, and the exhaust passage. Comprises a bypass passage through which the exhaust gas can bypass the first catalyst, and a flow path control means capable of regulating the flow of the exhaust gas to the bypass passage, wherein the exhaust gas temperature detection means comprises the The temperature of the exhaust gas introduced into the second catalyst is detected, and the control means controls the flow path control means when the temperature of the exhaust gas is lower than a preset bypass regulation temperature to control the bypass passage. The flow of the exhaust gas to is regulated.

  An internal combustion engine according to a fourth aspect of the present invention includes a radiator cooling means capable of cooling the radiator, and a cooling medium temperature detecting means for detecting a temperature of the cooling medium after cooling the exhaust gas introducing portion, The control means controls the radiator cooling means and the flow rate adjusting means stepwise based on the temperature of the cooling medium detected by the cooling medium temperature detecting means.

  In the internal combustion engine according to the fifth aspect of the present invention, the internal combustion engine includes a thermal load reducing unit capable of reducing a thermal load caused by the internal combustion engine body, and the control unit detects the temperature of the cooling medium detected by the cooling medium temperature detecting unit. When the temperature is higher than an overheat avoidance temperature for avoiding overheating of the supercharging means in advance, the thermal load reducing means is controlled to reduce the heat load caused by the exhaust gas.

  In the internal combustion engine according to the sixth aspect of the present invention, the thermal load reducing means includes fuel supply means capable of supplying fuel to a combustion chamber of the internal combustion engine body, and the control means includes the cooling medium temperature detection means. When the detected temperature of the cooling medium is higher than the overheat avoidance temperature, the fuel supply means is controlled so that the air-fuel ratio of the mixture of fuel and intake air in the internal combustion engine body is made leaner than the stoichiometric air-fuel ratio. It is characterized by setting.

  In the internal combustion engine according to the invention according to claim 7, the thermal load reducing means includes ignition means for igniting an air-fuel mixture of the fuel and intake air in a combustion chamber of the internal combustion engine body, and the control means When the temperature of the cooling medium detected by the cooling medium temperature detecting means is higher than the overheat avoidance temperature, the ignition means is controlled to set the ignition timing of the internal combustion engine body to the advance side. .

  In the internal combustion engine according to the invention according to claim 8, the thermal load reducing means includes intake air amount adjusting means for adjusting an intake air amount sucked into the internal combustion engine main body, and the control means is the cooling medium temperature. When the temperature of the cooling medium detected by the detecting means is higher than the overheat avoidance temperature, the intake air amount adjusting means is controlled to set the intake air amount sucked into the internal combustion engine body to the increasing side. Features.

  In an internal combustion engine according to a ninth aspect of the present invention, the internal combustion engine includes: a rotation speed detection unit that detects a rotation speed of the internal combustion engine body; and a load detection unit that detects a load of the internal combustion engine body. The overheat avoidance temperature is set based on a rotation speed of the internal combustion engine body detected by the speed detection means and a load of the internal combustion engine body detected by the load detection means.

  According to the internal combustion engine of the present invention, the exhaust gas introduction part for introducing the exhaust gas into the supercharging means is cooled by the supercharging means cooling system independent of the cooling system for cooling the internal combustion engine body, and is introduced into the catalyst. Since the coolant flow rate of the supercharging means cooling system is adjusted based on the temperature of the exhaust gas, overheating can be reliably prevented and catalyst purification performance can be maintained.

  Embodiments of an internal combustion engine according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  1 is a schematic sectional view of an engine according to Embodiment 1 of the present invention, FIG. 2 is a flowchart showing a flow of turbine cooling control of the engine according to Embodiment 1 of the present invention, and FIG. 3 is an embodiment of the present invention. 2 is a diagram showing the relationship between the exhaust gas temperature at the second catalyst inlet of the engine according to 1 and the control current of the electric water pump.

  As shown in FIG. 1, an engine 1 as an internal combustion engine according to the present embodiment introduces intake air into an engine body 2 in which a mixture of fuel and intake air as an internal combustion engine body burns, and the engine body 2. An intake passage 3, an exhaust passage 4 for exhausting exhaust gas from the engine body 2, and a turbocharger 5 as supercharging means for compressing and supercharging the intake air to the engine body 2 are provided. The engine body 2 is an engine mounted on a vehicle such as a passenger car or a truck, and the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke are performed while the piston 11 provided in the cylinder bore 12 is capable of reciprocating twice. This is a so-called four-cycle engine that performs a series of four strokes, but is not limited to this type of internal combustion engine, and can be applied to various internal combustion engines. The turbocharger 5 drives a compressor 52 as a compressor by a turbine 51 driven by exhaust gas exhausted from the engine body 2 to improve the output and fuel consumption of the engine body 2, and to the engine body 2. The intake air is supercharged, that is, compressed and supplied to increase the efficiency of filling the combustion chamber 13 with air.

  Specifically, as shown in FIG. 1, the engine 1 includes an engine body 2, an intake passage 3, an exhaust passage 4, a turbocharger 5, an air cleaner 6, an intercooler 7, a throttle valve 8, A surge tank 9 and a catalyst device 10 as a catalyst are provided.

  The engine body 2 includes a cylinder head 20 and a cylinder block 21. The cylinder head 20 is fastened on the cylinder block 21. Further, the engine body 2 includes a cylinder bore 12 in which the pistons 11 can reciprocate, a combustion chamber 13 provided on one side in the movement direction of the piston 11, and a crank chamber 14 provided on the other side in the movement direction of the piston 11. Prepare. The cylinder bore 12 is formed in a cylindrical shape inside the cylinder block 21. The piston 11 is fitted to the cylinder bore 12 so as to be movable up and down. The crank chamber 14 communicates with the cylinder bore 12. Here, the moving direction of the piston 11 is the axial direction of the cylinder bore 12 formed in a cylindrical shape. That is, the combustion chamber 13 is provided on one side in the axial direction of the cylinder bore 12 with the piston 11 in between, and the crank chamber 14 is provided on the other side. The engine body 2 includes a plurality of pistons 11, cylinder bores 12, combustion chambers 13, and crank chambers 14.

  Further, the engine body 2 is positioned above the combustion chamber 13 and mixed with an intake port 15 and an exhaust port 16 communicating with the combustion chamber 13, an injector 17 capable of directly injecting fuel into the combustion chamber 13. A spark plug 18 that ignites the mind and a crankshaft 19 that can rotate in conjunction with the reciprocating motion of the piston 11 are provided.

  The crankshaft 19 is rotatably supported in the crank chamber 14 so as to pass through the plurality of crank chambers 14, and each piston 11 is connected to the crankshaft 19 via a connecting rod (not shown). The The crankshaft 19 has a counterweight (not shown) around its axis. The reciprocating motion of each piston 11 is transmitted to the crankshaft 19 via the connecting rod, where it is converted into rotational motion and taken out as the output of the engine body 2.

  The combustion chamber 13 is provided on the opposite side of the crank chamber 14 with the piston 11 in between. A plurality of combustion chambers 13 are formed corresponding to the plurality of cylinder bores 12. Two intake ports 15 and two exhaust ports 16 are formed in the upper portion of the combustion chamber 13, that is, in the lower surface of the cylinder head 20. An intake valve 22 and an exhaust valve 23 are provided at the openings of the intake port 15 and the exhaust port 16. The intake valve 22 and the exhaust valve 23 can open and close the intake port 15 and the exhaust port 16, respectively, and can communicate the intake port 15 with the combustion chamber 13 and the combustion chamber 13 with the exhaust port 16. The injector 17 is attached to the intake port 15 side of the cylinder head 20. The injector 17 is provided with a tip inclined toward the center line of the cylinder bore 12 by a predetermined angle with respect to the vertical direction. The injector 17 injects fuel spray toward the top surface of the piston 11. The spark plug 18 is mounted between the intake port 15 and the exhaust port 16 on the ceiling portion of the combustion chamber 13, that is, on the lower surface of the cylinder head 20.

  The intake passage 3 supplies intake air to the engine body 2. An intake manifold 31 and an intake pipe 32 are provided. In the intake manifold 31, each intake port 15 is connected to one end side (downstream side in the intake direction), while the surge tank 9 is connected to the other end side (upstream side in the intake direction). The surge tank 9 is a tank that temporarily stores intake air to suppress intake pulsation. The intake pipe 32 is connected to the surge tank 9. Further, the intake pipe 32 is provided with the above-described air cleaner 6, intercooler 7, and throttle valve 8 in order from the upstream side with respect to the intake air intake direction. A compressor 52 of the turbocharger 5 described later is provided between the air cleaner 6 and the intercooler 7 on the intake pipe 32. The air cleaner 6 is a filter that is disposed at the inlet of the intake pipe 32 and removes dust, dust, and the like in the intake air. The intercooler 7 is a device that cools the air that has been compressed and heated by the compressor 52 of the turbocharger 5. The throttle valve 8 is a flow rate adjusting valve that adjusts the amount of air supplied to the engine body 2 (intake air amount), and is driven, for example, by operating an accelerator pedal (not shown).

  The exhaust passage 4 discharges exhaust gas from the engine body 2. The exhaust passage 4 has an exhaust manifold 41 and an exhaust pipe 42. Each exhaust port 16 is connected to one end side (upstream side in the exhaust direction) of the exhaust manifold 41, and a turbine 51 of the turbocharger 5 described later is connected to the other end side (upstream side in the intake direction). The exhaust pipe 42 is connected to the turbine 51.

  Here, the turbocharger 5 realizes higher output (or lower fuel consumption) of the engine body 2 by supercharging. The turbocharger 5 includes a turbine 51 disposed on the exhaust passage 4 and a compressor 52 disposed on the intake passage 3.

  The turbine 51 has a turbine wheel 53 as a wheel and a turbine housing 54 that accommodates the turbine wheel 53, while the compressor 52 has a compressor impeller 55 as an impeller and a compressor housing 56 that accommodates the compressor impeller 55. . The turbocharger 5 includes a rotor shaft 57 that connects the turbine wheel 53 and the compressor impeller 55. That is, the rotor shaft 57 is provided with the turbine wheel 53 on one end side, and the compressor impeller 55 is provided on the other end side. The turbine wheel 53 and the compressor impeller 55 have the rotation axis of the rotor shaft 57 as the rotation center. It can rotate together.

  Accordingly, in the turbocharger 5, the turbine wheel 53 of the turbine 51 is rotationally driven by the exhaust gas passing through the exhaust passage 4, and the power is transmitted to the compressor impeller 55 via the rotor shaft 57, so that the compressor impeller 55 is rotationally driven. Is done. Then, the compressor impeller 55 of the compressor 52 is rotationally driven, whereby the air in the intake pipe 32 is compressed and supplied (supercharged) to the engine body 2, thereby increasing the output of the engine 1.

  Further, the exhaust passage 4 includes a waste gate passage 43 as an exhaust passage that bypasses the turbine 51. The waste gate passage 43 has an inlet connected to the upstream side of the turbine 51 on the exhaust passage 4 and an outlet connected between the turbine 51 and a first catalyst 10a of the catalyst device 10 described later. The The wastegate passage 43 is provided with a wastegate valve (open / close valve) 44 that can open and close the wastegate passage 43. The waste gate valve (open / close valve) 44 opens and closes the waste gate passage 43 to adjust the amount of exhaust gas introduced into the turbine 51, thereby rotating the turbine wheel 53 of the turbine 51 and the compressor impeller 55 of the compressor 52. The number is adjusted.

  Further, the exhaust pipe 42 of the exhaust passage 4 is provided with a catalyst device 10 that purifies the exhaust gas downstream of the turbine 51 of the turbocharger 5 with respect to the exhaust gas exhaust direction. The catalyst device 10 is activated when the catalyst reaches a predetermined activation temperature or higher, thereby oxidizing and reducing harmful substances such as HC, CO, and NOx contained in the exhaust gas to purify the catalyst. Yes, sufficient purification efficiency of harmful substances can be obtained near the theoretical air-fuel ratio.

  More specifically, the catalyst device 10 includes a first catalyst 10a and a second catalyst 10b provided on the downstream side of the first catalyst 10a with respect to the exhaust gas exhaust direction. The exhaust passage 4 has a bypass passage 45 through which exhaust gas discharged from the engine body 2 can bypass the first catalyst 10a. That is, the exhaust pipe 42 of the exhaust passage 4 branches into the bypass passage 45 and the first catalyst passage 46 on the downstream side of the turbine 51, more specifically, on the downstream side of the outlet portion of the waste gate passage 43. , They merge again upstream of the second catalyst 10b. The first catalyst 10 a is provided in the first catalyst passage 46, and the flow path control valve 47 as flow path control means is provided in the bypass passage 45.

  The flow path control valve 47 is an open / close valve that can open and close the bypass passage 45 by the actuator 47a. The flow path control valve 47 closes the bypass passage 45 so that the exhaust gas to the bypass passage 45 is closed. The flow can be regulated. That is, when the flow control valve 47 is opened, exhaust gas flows through the bypass passage 45, so that the exhaust gas flows by bypassing the first catalyst 10a, while when the flow control valve 47 is closed, the exhaust gas is first It passes through the catalyst 10a and is purified here. The flow path control valve 47 is opened and closed according to the operating state of the engine 1, thereby controlling the flow of exhaust gas to the first catalyst 10 a and suppressing overheating of the first catalyst 10 a.

  For example, when the engine main body 2 is cold-started (warm-up) or is operated at a low rotation / low load, the flow control valve 47 is set to the closed position and the exhaust gas is sent to the first catalyst passage 46. The exhaust gas is purified by passing through the first catalyst 10a. The exhaust gas that has passed through the first catalyst 10a further passes through the second catalyst 10b downstream of the exhaust gas in the exhaust direction, and is purified by the second catalyst 10b. Since the first catalyst 10a is provided closer to the engine body 2 than the second catalyst 10b, the catalyst temperature is likely to rise, so the first catalyst 10a can be warmed up early and the engine Since the temperature of the exhaust gas is low during the warm-up operation of the main body 2 or during low rotation and low load, the first catalyst 10a that is easily exposed to high-temperature exhaust gas by setting the flow path control valve 47 to the closed position. Even when the exhaust gas is allowed to pass through, since the temperature of the exhaust gas is low, the temperature of the first catalyst 10a can be suppressed from becoming too high.

  On the other hand, when the engine body 2 is warmed up or operating at a high rotation / high load, the flow control valve 47 is set to the open position, and the exhaust gas is introduced into the bypass passage 45 so that the exhaust gas is discharged. Bypasses the first catalyst 10a, passes through the second catalyst 10b, and is purified by the second catalyst 10b. In this case, almost all of the exhaust gas flowing in the exhaust pipe 42 flows to the bypass passage 45, so that there is almost no exhaust gas flow in the first catalyst passage 46. As described above, since the exhaust gas hardly flows into the first catalyst passage 46 by setting the flow path control valve 47 to the open position, the exhaust gas does not pass through the first catalyst 10a, and the direction of the second catalyst 10b. And flows through the second catalyst 10b and is purified only by the second catalyst 10b. Further, when the engine body 2 is warmed up or operated at a high rotation / high load, the temperature of the exhaust gas becomes high, but the exhaust gas flows downstream while dissipating heat, and the second catalyst 10b Since it is located downstream of the first catalyst 10a in the gas exhaust direction, the temperature of the exhaust gas decreases when the high-temperature exhaust gas passes through the second catalyst 10b. It is suppressed that the temperature of 10b becomes too high.

  Further, the engine 1 is controlled to drive each part in accordance with the operating state by an electronic control unit (ECU: Electronic Control Unit) 90 as a control means mainly composed of a microcomputer. That is, the ECU 90 determines the fuel injection amount (fuel injection amount) based on the engine operating state such as the intake air amount, intake air temperature, intake pressure, throttle opening, accelerator opening, engine speed, engine coolant temperature detected by various sensors. Time), injection timing, ignition timing, etc. are determined, and the injector 17 and spark plug 18 are driven to execute fuel injection and ignition. The ECU 90 is also electrically connected to the throttle valve 8, the waste gate valve 44, and the flow path control valve 47, and controls the driving thereof.

  The ECU 90 includes a crank angle sensor 91 as a rotational speed detection means, a throttle position sensor 92 as a load detection means, an A / F sensor 93, and a second catalyst inlet exhaust gas temperature sensor 94 as an exhaust gas temperature detection means. Are electrically connected.

  The crank angle sensor 91 transmits the detected crank angle to the ECU 90. The ECU 90 determines the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke in each cylinder based on the received crank angle, and rotates the internal combustion engine body. The engine speed (rpm) of the engine body 2 as the speed is calculated. Here, the engine speed corresponds to the rotational speed of the crankshaft 19 in other words, and the higher the rotational speed of the crankshaft 19, the higher the rotational speed of the crankshaft 19 and the engine rotational speed.

  The throttle position sensor 92 detects the opening degree of the throttle valve 8, and transmits the detected opening degree of the throttle valve 8 to the ECU 90. The ECU 90 detects the engine of the engine body 2 based on the received opening degree of the throttle valve 8. Calculate the load.

  The A / F sensor 93 is provided upstream of the turbine 51 with respect to the exhaust direction on the exhaust passage 4, detects the air-fuel ratio of the exhaust gas, and transmits the detected air-fuel ratio to the ECU 90. The fuel injection amount by the injector 17 is corrected based on the air-fuel ratio. The A / F sensor 93 detects an exhaust gas air-fuel ratio of exhaust gas before being introduced into an exhaust gas purification catalyst (not shown) out of exhaust gas exhausted from the combustion chamber 13 to the exhaust port 16, and sends it to the ECU 90. Output. The air / fuel ratio (estimated air / fuel ratio) detected by the A / F sensor 93 is used for feedback control of the air / fuel ratio (theoretical air / fuel ratio) of the mixed gas composed of intake air and fuel. In other words, the A / F sensor 93 detects the exhaust air / fuel ratio from the rich region to the lean region from the oxygen concentration and the unburned gas concentration in the exhaust gas, and feeds this back to the ECU 90 to feed back the air / fuel ratio in the combustion chamber 13. It is possible to control the combustion so that the optimum combustion state in accordance with the operation state, for example, the air-fuel ratio becomes stoichiometric (theoretical air-fuel ratio).

  The second catalyst inlet exhaust gas temperature sensor 94 is provided at the inlet (upstream side) of the second catalyst 10b of the catalyst device 10, and the exhaust introduced into the second catalyst 10b at the inlet of the second catalyst 10b. The temperature of the gas is detected, and the detected second catalyst inlet exhaust gas temperature is transmitted to the ECU 90.

  In addition to the crank angle sensor 91, the throttle position sensor 92, the A / F sensor 93, and the second catalyst inlet exhaust gas temperature sensor 94, the ECU 90 includes an intake air temperature sensor for detecting the intake air temperature in the air cleaner, an accelerator. An accelerator sensor that detects the amount of pedal depression (accelerator opening), an intake pipe pressure sensor that detects the pressure in the intake passage downstream of the throttle valve 8, and a fuel pressure sensor that detects the fuel pressure in the fuel supply passage if necessary Various sensors such as are connected.

  In the engine body 2 of the engine 1 configured as described above, the piston 11 descends in the cylinder bore 12, whereby air is sucked into the combustion chamber 13 through the intake pipe 32, the intake manifold 31 and the intake port 15. (Intake stroke), this air and fuel injected from the injector 17 into the combustion chamber 13 are mixed to form an air-fuel mixture. Then, the air-fuel mixture is compressed by the piston 11 going up through the cylinder bore 12 via the intake stroke bottom dead center (compression stroke), and when the piston 11 approaches the top dead center of the compression stroke, the mixture is made into the air-fuel mixture by the spark plug 18. It is ignited, the air-fuel mixture burns, and the piston 11 is lowered by the combustion pressure (expansion stroke). The air-fuel mixture after combustion passes through the exhaust port 16, the exhaust manifold 41, and the exhaust pipe 42 communicating with the combustion chamber 13 as the piston 11 rises again toward the top dead center of the intake stroke via the expansion stroke bottom dead center. Released as exhaust gas (exhaust stroke). The reciprocating motion of the piston 11 in the cylinder bore 12 is transmitted to the crankshaft 19 through the connecting rod, where it is converted into a rotational motion and taken out as an output. By rotating further, the cylinder bore 12 reciprocates as the crankshaft 19 rotates. By rotating the crankshaft 19 twice, the piston 11 reciprocates the cylinder bore 12 twice. During this time, a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke are performed, and once in the combustion chamber 13. Explosion takes place.

  During this time, the turbine wheel 53 provided in the turbine 51 of the turbocharger 5 is rotationally driven by the exhaust gas passing through the exhaust passage 4, and the rotational power is transmitted to the compressor impeller 55 via the rotor shaft 57, so that the compressor impeller 55 rotates. Driven. As a result, the intake air in the intake pipe 32 is compressed and supercharged to the engine body 2. For this reason, the charging efficiency of air into the combustion chamber 13 can be increased, and the output of the engine 1 can be increased. At this time, the exhaust gas discharged from the combustion chamber 13 to the exhaust passage 4 warms and activates the first catalyst 10a and the second catalyst 10b of the catalyst device 10, and the contained harmful substances are purified. From the atmosphere.

By the way, in recent years, in order to realize downsizing of the engine 1, there is one that further increases the output of the engine body 2 of the engine 1 by setting the supercharging pressure by the turbocharger 5 as described above. Accordingly, there is a technology that realizes a substantial large displacement even though the displacement is small. Then, in the engine 1 in which the efficiency of filling the combustion chamber 13 with air is increased in this way, for example, the exhaust air ratio is increased over the entire operation region due to demands for exhaust gas purification (NOx reduction) and fuel efficiency improvement (CO ₂ reduction). (Air excess ratio λ = actual air / fuel ratio / theoretical air / fuel ratio, if λ> 1, the air / fuel ratio is on the lean side, whereas if λ <1, the air / fuel ratio is on the rich side) = 1 When operating with stoichiometry (theoretical air-fuel ratio), the exhaust gas temperature discharged from the combustion chamber 13 tends to be relatively high. For this reason, in such an engine 1, it is necessary to increase the heat resistance of the exhaust gas introduction part 60 that introduces the exhaust gas into the turbine wheel 53 of the turbocharger 5 in order to prevent overheating. On the other hand, when a high heat-resistant material is frequently used in the exhaust gas introduction part 60, there is also an influence of a recent increase in material cost, and as a result, there is a risk of increasing the cost. For this reason, the engine 1 of the present embodiment is provided with the water jacket 71 in the exhaust gas introduction part 60 that becomes high temperature by the exhaust gas, and the cooling water as the cooling medium is supplied to the water jacket 71 so that the exhaust gas introduction part 60 Is cooling. Here, for example, if the exhaust gas introduction unit 60 is overcooled in the operation region where the heat load of the engine 1 is low, the exhaust gas temperature is excessively lowered accordingly, and as a result, the catalyst of the catalyst device 10 is reduced. There is a possibility that the bed temperature may be lower than a predetermined activation temperature, and thus the purification performance of the catalyst device 10 may be reduced.

  Therefore, the engine 1 of the present embodiment cools the exhaust gas introduction portion 60 that introduces exhaust gas into the turbocharger 5 by the turbine cooling system 70 as a supercharging means cooling system independent of the cooling system that cools the engine body 2. At the same time, by adjusting the cooling water flow rate of the turbine cooling system 70 based on the temperature of the exhaust gas introduced into the second catalyst 10b of the catalyst device 10 used in the normal operation state, the overheating is surely prevented. The proper catalyst purification performance in the catalyst device 10 is maintained.

  Specifically, as shown in FIG. 1, the turbine cooling system 70 includes the above-described water jacket 71 as a cooling means for exhaust gas introduction, a cooling water circulation passage 72 as a cooling medium passage, a radiator 73, and a flow rate adjustment. And an electric water pump 74 as means.

  Here, the exhaust gas introduction part 60 for introducing exhaust gas to the turbine wheel 53 of the turbocharger 5 includes an exhaust manifold 41 and a turbine housing 54 as an exhaust introduction passage for introducing exhaust gas to the turbine 51 of the turbocharger 5. Consists of. The water jacket 71 is provided in at least one of the exhaust manifold 41 and the turbine housing 54 that form the exhaust gas introduction portion 60. The water jacket 71 of the present embodiment is provided at a connection portion connected to the turbine housing 54 in the exhaust manifold 41. The water jacket 71 is provided so as to cover the outer periphery of the connection portion between the exhaust manifold 41 and the turbine housing 54. The cooling water circulation passage 72 is a loop-like passage for circulating the cooling water supplied to the water jacket 71 and is provided independently from a cooling system (not shown) for cooling the engine body 2. The water jacket 71 is provided on the cooling water circulation passage 72, and therefore, the water jacket 71 is supplied with cooling water circulating through the cooling water circulation passage 72 to the exhaust manifold of the exhaust gas introduction unit 60. 41 can be cooled.

  In the cooling water circulation passage 72, a radiator 73, an electric water pump 74, and a cooling water temperature sensor 95 as a cooling medium temperature detecting means are installed in order from the water jacket 71 side in the cooling water circulation direction. The cooling water temperature sensor 95 is provided between the water jacket 71 and the radiator 73 in the cooling water circulation passage 72, downstream of the water jacket 71 and upstream of the radiator 73 with respect to the cooling water circulation direction. The temperature of the cooling water is detected. That is, the cooling water temperature sensor 95 detects the temperature of the cooling water after cooling the exhaust manifold 41 forming the exhaust gas introduction unit 60 and transmits the detected temperature of the cooling water to the ECU 90. The electric water pump 74 is provided between the radiator 73 and the water jacket 71 in the cooling water circulation passage 72. In other words, the cooling water circulation passage 72 connects the outlet side of the water jacket 71 and the radiator 73, connects the radiator 73 and the electric water pump 74, and further, the inlet side of the electric water pump 74 and the water jacket 71. And connect.

  The radiator 73 acts as a heat radiating unit and can cool the cooling water circulating in the cooling water circulation passage 72 by traveling wind or the like. Therefore, the cooling water whose temperature has been increased by cooling the exhaust manifold 41 of the exhaust gas introduction section 60 by the water jacket 71 radiates heat when passing through the radiator 73. For this reason, the cooling water dissipates heat when passing through the radiator 73 and the temperature decreases, and when heat exchange is performed with the exhaust gas introduction unit 60 by the water jacket 71, the temperature is increased by absorbing heat. That is, the cooling water radiates the heat absorbed by the exhaust gas introduction part 60 by the radiator 73.

  The electric water pump 74 is electrically driven and can pump the cooling water in the cooling water circulation passage 72, and therefore the electric water pump 74 can adjust the flow rate of the cooling water supplied to the water jacket 71. . Then, the cooling water is circulated between the water jacket 71 and the radiator 73 by the electric water pump 74 to cool the exhaust manifold 41 that forms the exhaust gas introduction portion 60 by the cooling water, while cooling the exhaust manifold 41. Cooling water whose temperature has risen is cooled by the radiator 73. The electric water pump 74 is electrically connected to the ECU 90 and its drive is controlled.

  Further, the turbine cooling system 70 of this embodiment includes an electric fan 75 as a radiator cooling means capable of cooling the radiator 73. The electric fan 75 is provided to face the radiator 73. Accordingly, when it is desired to forcibly reduce the temperature of the cooling water, such as when the running wind does not hit the radiator 73 or when the running wind is low, the radiator 73 is forced by driving the electric fan 75. Can be cooled to. The electric fan 75 is electrically connected to the ECU 90 and its drive is controlled.

  Then, the ECU 90 as control means controls the driving of the electric water pump 74 based on the second catalyst inlet exhaust gas temperature detected by the second catalyst inlet exhaust gas temperature sensor 94. Further, the ECU 90 controls the driving of the electric fan 75 and the electric water pump 74 in a stepwise manner based on the cooling water temperature after cooling the exhaust manifold 41 constituting the exhaust gas introduction unit 60 detected by the cooling water temperature sensor 95. To do.

  Next, the flow of turbine cooling control in the engine 1 will be described with reference to FIG. In this turbine cooling control, first, the ECU 90 detects and reads the cooling water temperature WT after cooling the exhaust manifold 41 forming the exhaust gas introduction unit 60 with the water jacket 71 by the cooling water temperature sensor 95 (S100). Then, the ECU 90 sets the warm normal state temperature TW1, the overheat prevention temperature TW2, the overheat avoidance temperature TW3, the overheat countermeasure temperature TW4, and the coolant temperature detected in S100 as the reference temperature (cooling water temperature serving as a reference for control) TW. Compare WT, and according to the comparison result, that is, according to the temperature of the coolant temperature WT, warm-up mode (00 control selection), normal mode (01 control selection), overheat prevention (02 control selection), overheat avoidance An appropriate control mode is selected from (03 control selection) and overheat countermeasure (04 control selection). Here, each reference temperature TW of the warm normal state temperature TW1, the overheat prevention temperature TW2, the overheat avoidance temperature TW3, and the overheat countermeasure temperature TW4 depends on the specifications of the engine 1 and the turbocharger 5 [TW1 <TW2 <TW3. What is necessary is just to set as a fixed threshold value beforehand so that it may become <TW4].

  Specifically, the ECU 90 first compares the coolant temperature WT with the warm normal state temperature TW1, and determines whether or not the coolant temperature WT is higher than the warm normal state temperature TW1 (S102). When it is determined that the cooling water temperature WT is equal to or lower than the warm normal state temperature TW1 (S102: No), since the engine 1 is in the cold state, the electric water pump 74 is set as the warm-up mode (00 control selection). And the drive of the electric fan 75 is controlled, the electric water pump 74 and the electric fan 75 are set to a stop state, and it complete | finishes (S104). Thereby, the circulation of the cooling water in the turbine cooling system 70 is stopped by setting the electric water pump 74 and the electric fan 75 to the stopped state, and the cooling of the exhaust manifold 41 by the water jacket 71 and the cooling of the exhaust gas associated therewith are performed. Stopped. As a result, the temperature reduction of the exhaust gas is prevented, so that the warm-up property of the catalyst device 10 can be improved.

  When it is determined that the coolant temperature WT is higher than the warm normal state temperature TW1 (S102: Yes), the ECU 90 compares the coolant temperature WT with the overheat prevention temperature TW2, and the coolant temperature WT is overheat prevention temperature TW2. It is determined whether it is higher (S106). When it is determined that the cooling water temperature WT is equal to or lower than the overheat prevention temperature TW2 (S106: No), since the engine 1 is in a normal warm operation state, the ECU 90 performs the electric operation in the normal mode (01 control selection). The drive of the water pump 74 and the electric fan 75 is controlled and the electric fan 75 is stopped, while the control of the electric water pump 74 is controlled to the second catalyst inlet exhaust gas temperature detected by the second catalyst inlet exhaust gas temperature sensor 94. The control mode is set based on this, and the process ends (S108).

  Here, FIG. 3 is a diagram showing the relationship between the second catalyst inlet exhaust gas temperature and the control current of the electric water pump 74 in the normal mode (01 control selection) of S108, and the horizontal axis is the second catalyst inlet exhaust gas. The temperature GT and the vertical axis are the control current of the electric water pump 74. As shown in FIG. 3, the ECU 90 stores the control current of the electric water pump 74 in advance in a storage unit (not shown) as a map in association with the second catalyst inlet exhaust gas temperature GT. Then, in the normal mode of S108 (01 control selection), the ECU 90 reads a predetermined control current of the electric water pump 74 from this map based on the second catalyst inlet exhaust gas temperature GT, and the read out electric water pump 74 Based on the control current, the drive of the electric water pump 74 is controlled.

  That is, in the normal mode (01 control selection) of S108, the ECU 90 controls the control current of the electric water pump 74 as the second catalyst inlet exhaust gas temperature GT becomes higher in a region where the second catalyst inlet exhaust gas temperature GT is higher than a predetermined value. To increase the operation output of the electric water pump 74, thereby increasing the flow rate of the cooling water supplied to the water jacket 71. As a result, in the operation region where the exhaust gas temperature is relatively high, the second catalyst inlet exhaust gas temperature GT is high, so that the cooling water supplied to the water jacket 71 while maintaining the catalyst device 10 at a predetermined activation temperature. The exhaust manifold 41 forming the exhaust gas introduction part 60 can be sufficiently cooled by increasing the flow rate of. At this time, the exhaust gas is also cooled along with the cooling of the exhaust manifold 41, so that the first catalyst 10a and the second catalyst 10b of the catalyst device 10 can be prevented from being thermally deteriorated. On the other hand, in the region where the second catalyst inlet exhaust gas temperature GT is higher than a predetermined value, the control current of the electric water pump 74 is lowered and the operation output of the electric water pump 74 is lowered as the second catalyst inlet exhaust gas temperature GT becomes lower. Thereby, the flow rate of the cooling water supplied to the water jacket 71 is decreased. As a result, in the operation region where the exhaust gas temperature is relatively low, the cooling of the exhaust manifold 41 by the water jacket 71 and the accompanying cooling of the exhaust gas are suppressed. As a result, since the temperature drop of the exhaust gas is suppressed, it is possible to suppress the temperature of the catalyst device 10 from being excessively lowered, and maintain the catalyst device 10 at a predetermined activation temperature to ensure proper purification performance. At this time, even if the flow rate of the cooling water supplied to the water jacket 71 is reduced, the exhaust gas temperature is relatively low, so that the exhaust manifold 41 forming the exhaust gas introduction unit 60 is burned in or the turbocharger 5 is overheated. Can be prevented. As a result, by adjusting the flow rate of the cooling water supplied to the water jacket 71 based on the temperature of the exhaust gas introduced into the second catalyst 10b of the catalyst device 10, it is possible to ensure overheating in the operation region where the heat load is high. In the operation region where the heat load is low, it is possible to prevent the temperature of the catalyst device 10 from being excessively lowered and maintain proper catalyst purification performance in the catalyst device 10. At this time, since the turbine cooling system 70 is provided as a separate system independently of the cooling system for cooling the engine body 2, the temperature of the cooling water circulating in the turbine cooling system 70 can be easily controlled, and the turbine The temperature of the cooling water circulating through the cooling system 70 can be quickly set to an appropriate temperature according to the operating state of the engine 1.

  When it is determined that the coolant temperature WT is higher than the overheat prevention temperature TW2 (S106: Yes), the ECU 90 compares the coolant temperature WT with the overheat avoidance temperature TW3, and the coolant temperature WT is higher than the overheat avoidance temperature TW3. It is determined whether or not (S110). If it is determined that the cooling water temperature WT is equal to or lower than the overheat avoidance temperature TW3 (S110: No), the turbocharger 5 is not immediately overheated, but the cooling water temperature WT is higher than normal. The ECU 90 controls driving of the electric water pump 74 and the electric fan 75 to prevent overheating (02 control selection), starts the operation of the electric fan 75, and sets the electric water pump 74 to the second catalyst inlet exhaust gas temperature GT. First, the operation output is increased and the process ends (S112). As a result, the electric fan 75 is started to operate and the operation output of the electric water pump 74 is increased, whereby the radiator 73 is forcibly cooled and the flow rate of the cooling water supplied to the water jacket 71 is further increased. Therefore, the cooling performance of the exhaust manifold 41 by the water jacket 71 is improved, and overheating of the turbocharger 5 can be prevented.

  When it is determined that the coolant temperature WT is higher than the overheat avoidance temperature TW3 (S110: Yes), the ECU 90 compares the coolant temperature WT with the overheat countermeasure temperature TW4, and the coolant temperature WT is higher than the overheat countermeasure temperature TW4. It is determined whether or not (S114). When it is determined that the cooling water temperature WT is equal to or lower than the overheat countermeasure temperature TW4 (S114: No), the turbocharger 5 has not yet overheated but is in a state just before overheating, so the ECU 90 avoids overheating (03 control). As the selection, the driving of the electric water pump 74 and the electric fan 75 is controlled, and the operation outputs of the electric fan 75 and the electric water pump 74 are increased to the maximum (S116). Thereby, by increasing the operation outputs of the electric fan 75 and the electric water pump 74 to the maximum, the cooling performance of the exhaust manifold 41 by the water jacket 71 is improved to the maximum, and overheating of the turbocharger 5 can be avoided.

  When it is determined that the cooling water temperature WT is higher than the overheat countermeasure temperature TW4 (S114: Yes), the turbocharger 5 is in an overheated state, so the ECU 90 performs the throttle as an overheat countermeasure (04 control selection). By decreasing the opening degree of the valve 8 and increasing the opening degree of the waste gate valve 44 to reduce the supercharging pressure, the output of the engine body 2 is lowered, and the temperature of the exhaust gas discharged from the engine body 2 itself. Is finished (S118). However, even in this case, since the turbine cooling system 70 is provided as a separate system independently of the cooling system for cooling the engine main body 2, the engine main body 2 even if the turbocharger 5 or the exhaust gas introduction unit 60 is overheated. The cooling water temperature of the cooling system that cools the engine can be prevented from rising along with this, and overheating of the engine body 2 itself can be prevented from being induced. Therefore, even if the turbocharger 5 and the exhaust gas introduction unit 60 are overheated and seized or damaged, the cooling system on the engine body 2 side is not affected, and the engine body 2 is also overheated and seized or damaged. Can be prevented from occurring.

  According to the engine 1 according to the embodiment of the present invention described above, the exhaust gas is discharged from the engine main body 2 and the exhaust passage 4 having the catalyst device 10 for purifying the exhaust gas, and the exhaust gas introduction unit 60 are provided. A turbocharger 5 that compresses and supercharges intake air to the engine body 2 by being driven by exhaust gas introduced through the engine, a water jacket 71 that can cool the exhaust gas introduction part 60 from cooling water, and an engine body 2 is supplied to the water jacket 71, a cooling water circulation passage 72 that can circulate cooling water to the water jacket 71 independently of the cooling system that cools the cooling water 2, a radiator 73 that can cool the cooling water that circulates in the cooling water circulation passage 72, and the water jacket 71. A turbine cooling system 70 having an electric water pump 74 capable of adjusting the flow rate of cooling water, and the second catalyst 10 of the catalyst device 10. A second catalyst inlet exhaust gas temperature sensor 94 for detecting the temperature of the exhaust gas introduced into the engine, and an ECU 90 for controlling the electric water pump 74 based on the temperature of the exhaust gas detected by the second catalyst inlet exhaust gas temperature sensor 94; Is provided.

  Therefore, the exhaust gas introduction part 60 for introducing the exhaust gas into the turbocharger 5 is cooled by the turbine cooling system 70 independent of the cooling system for cooling the engine body 2, and the exhaust gas introduced into the second catalyst 10 b of the catalyst device 10. Since the coolant flow rate of the turbine cooling system 70 is adjusted based on the gas temperature, overheating can be reliably prevented in an operation region where the heat load is high. On the other hand, in the operation region where the heat load is low, it is possible to prevent the temperature of the catalyst device 10 from excessively decreasing and maintain an appropriate catalyst purification performance in the catalyst device 10, and to reduce exhaust energy due to excessively low exhaust gas temperature. As a result, it is possible to prevent the turbo response from deteriorating. Further, since the turbine cooling system 70 is provided as a separate system independently of the cooling system for cooling the engine body 2, the temperature of the cooling water circulating in the turbine cooling system 70 can be easily controlled, and the turbine cooling system 70 The temperature of the cooling water circulating through the engine can be quickly set to an appropriate temperature according to the operating state of the engine 1.

  Furthermore, according to the engine 1 according to the embodiment of the present invention described above, the exhaust passage 4 has the exhaust manifold 41 for introducing the exhaust gas to the turbocharger 5, and the turbocharger 5 is introduced from the exhaust manifold 41. A turbine 51 in which a turbine wheel 53 that is rotationally driven by the exhaust gas is housed in a turbine housing 54, and a compressor 52 in which a compressor impeller 55 that is rotated by the turbine wheel 53 being rotationally driven is housed in a compressor housing 56. The exhaust gas introduction unit 60 includes the exhaust manifold 41 and the turbine housing 54, and the water jacket 71 is provided in the exhaust manifold 41. Therefore, since the water jacket 71 is provided in the exhaust manifold 41 that forms the exhaust gas introduction unit 60, the exhaust gas introduced into the turbocharger 5 as the exhaust manifold 41 is cooled by the water jacket 71 based on the exhaust gas temperature. Can be cooled to an appropriate temperature.

  Furthermore, according to the engine 1 which concerns on the Example of this invention demonstrated above, the cooling water temperature which detects the temperature of the cooling water after cooling the electric fan 75 which can cool the radiator 73, and the exhaust gas introduction part 60. The ECU 90 controls the electric fan 75 and the electric water pump 74 in a stepwise manner based on the temperature of the cooling water detected by the cooling water temperature sensor 95. Therefore, the operation outputs of the electric fan 75 and the electric water pump 74 are stepwise according to the warm normal state temperature TW1, the overheat prevention temperature TW2, the overheat avoidance temperature TW3, and the overheat countermeasure temperature TW4 set with respect to the cooling water temperature WT. Since the frequency of thermal load reduction, in other words, the frequency of output suppression can be reduced, the catalyst purification performance is maintained while reliably preventing overheating, and more efficient operation is realized. be able to.

  The internal combustion engine according to the above-described embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope described in the claims. In the above description, the engine main body 2 has been described as an in-cylinder injection internal combustion engine main body, but is not limited thereto, and may be a so-called port injection internal combustion engine main body that injects fuel into the intake port 15.

  Further, in the above description, the flow rate adjusting means has been described as being the electric water pump 74 that is electrically driven. You may comprise by the mechanical water pump which can pump the cooling water of the channel | path 72, and the flow control valve which can adjust the flow volume of the cooling water supplied to the water jacket 71 by opening and closing the cooling water circulation channel | path 72. . In the above description, the radiator cooling means is described as being the electric fan 75, but is not limited thereto.

  In the above description, the load detecting means for detecting the load of the internal combustion engine body is described as being the throttle position sensor 92. However, the present invention is not limited to this, and based on the accelerator opening detected by the accelerator opening sensor. It may be calculated or calculated based on the engine speed detected by the crank angle sensor 91 or the like. In the above description, the catalyst device 10 as a catalyst has been described as having the first catalyst 10a and the second catalyst 10b, but may be one.

  FIG. 4 is a flowchart showing a flow of the first catalyst bypass stop control of the engine according to the second embodiment of the present invention. The internal combustion engine according to the second embodiment has substantially the same configuration as the internal combustion engine according to the first embodiment, but is different from the internal combustion engine according to the first embodiment in that the first catalyst bypass stop control is executed in a predetermined operation state. Different. In addition, about the structure, effect | action, and effect which are common in the Example mentioned above, while overlapping description is abbreviate | omitted as much as possible, the same code | symbol is attached | subjected. Also, refer to FIG. 1 for the configuration of the main part.

  As shown in FIG. 4, the engine 201 as the internal combustion engine according to the second embodiment has a second catalyst detected by the second catalyst inlet exhaust gas temperature sensor 94 during execution of the normal mode (01 control) described in FIG. 2. When the catalyst inlet exhaust gas temperature GT is lower than the preset bypass regulation temperature TG, the flow control valve 47 (see FIG. 1) is controlled to regulate the flow of exhaust gas to the bypass passage 45 (see FIG. 1). . That is, the ECU 90 (see FIG. 1) first reads the second catalyst inlet exhaust gas temperature GT detected by the second catalyst inlet exhaust gas temperature sensor 94 (S200). Next, the ECU 90 (see FIG. 1) determines whether or not the second catalyst inlet exhaust gas temperature GT read in S200 is lower than the bypass regulation temperature TG (S202). When it is determined that the second catalyst inlet exhaust gas temperature GT is equal to or higher than the bypass regulation temperature TG (S202: No), the first catalyst bypass stop control is terminated as it is. When it is determined that the second catalyst inlet exhaust gas temperature GT is lower than the bypass regulation temperature TG (S202: Yes), the ECU 90 determines whether or not the first catalyst 10a is being bypassed, that is, the flow path control valve 47 is It is determined whether or not it is in the open position (S204). When it is determined that the first catalyst 10a is not being bypassed (S204: No), the first catalyst bypass stop control is terminated as it is. When it is determined that the first catalyst 10a is being bypassed (S204: Yes), the ECU 90 drives the actuator 47a of the flow path control valve 47 to set the flow path control valve 47 to the closed position (S206), and ends. To do. Thereby, for example, when the engine main body 2 is operated at a low rotation and a low load, the exhaust gas is excessively cooled along with the cooling of the exhaust manifold 41 by the water jacket 71 of the turbine cooling system 70, and the second Even when the temperature of the catalyst 10b has dropped to the vicinity of the catalyst activation temperature, the exhaust gas is introduced into the first catalyst 10a that is provided near the engine body 2 and is easily exposed to exhaust gas having a temperature higher than that of the second catalyst 10b. By purifying with the first catalyst 10a, it is possible to prevent deterioration of exhaust gas purification performance due to overcooling under low temperature environment conditions. Note that the bypass regulation temperature TG may be appropriately set in advance according to the catalyst activation temperature of the second catalyst 10b.

  According to the engine 201 according to the embodiment of the present invention described above, the exhaust gas introduction unit 60 that introduces exhaust gas into the turbocharger 5 is cooled by the turbine cooling system 70 independent of the cooling system that cools the engine body 2. At the same time, since the cooling water flow rate of the turbine cooling system 70 is adjusted based on the temperature of the exhaust gas introduced into the second catalyst 10b of the catalyst device 10, it is possible to reliably prevent overheating in an operation region where the heat load is high. it can. On the other hand, in the operation region where the heat load is low, it is possible to prevent the temperature of the catalyst device 10 from excessively decreasing and maintain an appropriate catalyst purification performance in the catalyst device 10, and to reduce exhaust energy due to excessively low exhaust gas temperature. As a result, it is possible to prevent the turbo response from deteriorating. Further, since the turbine cooling system 70 is provided as a separate system independently of the cooling system for cooling the engine body 2, the temperature of the cooling water circulating in the turbine cooling system 70 can be easily controlled, and the turbine cooling system 70 The temperature of the cooling water circulating through the engine can be quickly set to an appropriate temperature according to the operating state of the engine 1.

  Furthermore, according to the engine 201 according to the embodiment of the present invention described above, the catalyst device 10 includes the first catalyst 10a and the first catalyst 10a provided downstream of the first catalyst 10a with respect to the exhaust gas exhaust direction. The exhaust passage 4 includes a bypass passage 45 in which exhaust gas can bypass the first catalyst 10a, and a flow path control valve 47 that can regulate the flow of exhaust gas to the bypass passage 45. The second catalyst inlet exhaust gas temperature sensor 94 detects the temperature of the exhaust gas introduced into the second catalyst 10b, and the ECU 90, a bypass restriction temperature TG at which the second catalyst inlet exhaust gas temperature GT is preset. When it is lower, the flow control valve 47 is controlled to restrict the flow of exhaust gas to the bypass passage 45. Therefore, even when the exhaust gas is cooled excessively along with the cooling of the exhaust manifold 41 by the water jacket 71 of the turbine cooling system 70, the exhaust gas is exposed to the exhaust gas that is provided near the engine body 2 and is higher in temperature than the second catalyst 10b. By introducing exhaust gas into the first catalyst 10a, which is easy to purify, and purifying with the first catalyst 10a, it is possible to prevent deterioration of exhaust gas purification performance due to overcooling under low temperature environment conditions.

  FIG. 5 is a schematic cross-sectional view illustrating a configuration of a main part of a turbocharger provided in an engine according to Embodiment 3 of the present invention. The internal combustion engine according to the third embodiment has substantially the same configuration as that of the internal combustion engine according to the first embodiment, but is different from the internal combustion engine according to the first embodiment in that an exhaust gas introduction part cooling means is provided in the turbine housing. Different. In addition, about the structure, effect | action, and effect which are common in the Example mentioned above, while overlapping description is abbreviate | omitted as much as possible, the same code | symbol is attached | subjected. Also, refer to FIG. 1 for the configuration of the main part.

  First, the configuration of the turbine 351 of the turbocharger 305 as supercharging means provided in the engine 301 as the internal combustion engine of the third embodiment will be described in detail with reference to FIG. The turbine 351 includes a turbine wheel 353 as a wheel and a turbine housing 354 that accommodates the turbine wheel 353.

  Specifically, the turbocharger 305 includes a turbine 351 and a compressor 352 (substantially the same configuration as the compressor 52 shown in FIG. 1) that are connected to each other via a bearing portion 358. The bearing portion 358 includes a center housing 359 and a bearing 359 a that rotatably supports the rotor shaft 357 within the center housing 359. The rotor shaft 357 protrudes from the center housing 359 at the left and right ends. As described above, the rotor shaft 357 is joined to one end thereof so that the turbine wheel 353 constituting the turbine 351 can rotate integrally, and the turbine wheel 353 is accommodated in the turbine housing 354. On the other hand, the rotor shaft 357 is joined to the other end thereof so that a compressor impeller 355 constituting the compressor 352 can rotate integrally.

  The turbine housing 354 includes an exhaust inlet 361, an exhaust outlet 362, and a scroll portion 363 that communicates the exhaust inlet 361 and the exhaust outlet 362. The turbine wheel 353 is rotatably accommodated in the scroll part 363. In the turbine housing 354, a scroll wall 364, an introduction nozzle 365, and a discharge nozzle 366 are integrally formed. The scroll wall 364 forms a scroll portion 363 as a spiral exhaust passage in which the passage area gradually decreases. The introduction nozzle 365 is formed in a substantially cylindrical shape, and an exhaust introduction port 361 is formed inside. The discharge nozzle 366 is formed in a substantially cylindrical shape, and forms an exhaust discharge port 362 inside. The introduction nozzle 365 is formed so as to introduce the exhaust gas in the tangential direction of the spiral scroll portion 363, while the discharge nozzle 366 is arranged so that the cylindrical axis is located at the approximate center of the spiral of the scroll portion 363. It is formed. The axis of the discharge nozzle 366 is substantially perpendicular to the axis of the cylindrical introduction nozzle 365. The introduction nozzle 365 and the discharge nozzle 366 are formed so as to protrude outward from the scroll wall 364. The exhaust introduction port 361 as a hollow portion of the introduction nozzle 365 and the exhaust discharge port 362 as a hollow portion of the discharge nozzle 366 are communicated with each other via the scroll portion 363 as described above.

  The turbine wheel 353 is fixed to one end of the rotor shaft 357 so as to be positioned substantially at the center of the spiral of the scroll portion 363 formed in the turbine housing 354. An exhaust manifold 41 (see FIG. 1) of the exhaust passage 4 (see FIG. 1) is connected to the introduction nozzle 365 from the engine body 2 (see FIG. 1), and the exhaust gas of the engine body 2 is introduced from the exhaust introduction port 361. Then, it is guided to the turbine wheel 353 through the scroll part 363 and flows in the direction of the exhaust discharge port 362 and is discharged. During this time, the exhaust gas flows into the turbine wheel 353, hits a plurality of blades, and rotates the turbine wheel 353. When the turbine wheel 353 rotates, the rotor shaft 357 fixed to the turbine wheel 353 also rotates together, and the compressor impeller 355 fixed to the other end of the rotor shaft 357 also rotates together. To do. As a result, the intake air in the intake pipe 32 (see FIG. 1) is compressed and supercharged to the engine body 2 (see FIG. 1).

  The turbine cooling system 370 provided in the engine 301 includes a water jacket 371 as an exhaust gas introduction part cooling means, a cooling water circulation passage 372 as a cooling medium passage, a radiator 373, and an electric water pump 374 as a flow rate adjusting means. And an electric fan 375 as a radiator cooling means.

  Here, the exhaust gas introduction part 360 that introduces exhaust gas into the turbine wheel 353 of the turbocharger 305 is configured to include an exhaust manifold 41 (see FIG. 1) as an exhaust introduction passage and a turbine housing 354. The water jacket 371 is provided in at least one of the exhaust manifold 41 and the turbine housing 354 that form the exhaust gas introduction part 360. The water jacket 371 of this embodiment is provided in the turbine housing 354. More specifically, the water jacket 371 is annularly provided on the scroll wall 364 on the bearing portion 358 side. The cooling water circulation passage 372 is a loop-like passage for circulating the cooling water supplied to the water jacket 371, and is provided independently from the cooling system for cooling the engine body 2 (see FIG. 1). The water jacket 371 is provided on the cooling water circulation passage 372. Therefore, the water jacket 371 is supplied with cooling water circulating through the cooling water circulation passage 372, so that the turbine housing of the exhaust gas introduction unit 360 is provided. 354 can be cooled.

  The center housing 359 that houses the bearing 359 a is provided with a bearing water jacket 367 in addition to the water jacket 371. The bearing water jacket 367 cools the sliding portion of the bearing 359a with cooling water supplied from a cooling system that cools the engine body 2 (see FIG. 1). A lubricating oil passage 368 is also provided in the vicinity of the bearing water jacket 367 of the center housing 359. The lubricating oil passage 368 lubricates the sliding portion of the bearing 359a with lubricating oil supplied from a lubricating system that lubricates the engine body 2 (see FIG. 1).

  The radiator 373 can cool the cooling water circulating in the cooling water circulation passage 372. The electric water pump 374 can adjust the flow rate of the cooling water supplied to the water jacket 371. The electric fan 375 can cool the radiator 373. Then, the ECU 90 controls the driving of the electric water pump 374 based on the second catalyst inlet exhaust gas temperature detected by the second catalyst inlet exhaust gas temperature sensor 94. Further, the ECU 90, as in the first embodiment, determines the electric fan 375 and the electric water pump based on the cooling water temperature after cooling the turbine housing 354 forming the exhaust gas introduction part 360 detected by the cooling water temperature sensor 95. The drive of 374 is controlled stepwise.

  According to the engine 301 according to the embodiment of the present invention described above, the exhaust gas introduction unit 360 that introduces exhaust gas into the turbocharger 305 is cooled by the turbine cooling system 370 that is independent of the cooling system that cools the engine body 2. At the same time, since the cooling water flow rate of the turbine cooling system 370 is adjusted based on the temperature of the exhaust gas introduced into the second catalyst 10b of the catalyst device 10, it is possible to reliably prevent overheating in an operation region where the heat load is high. it can. On the other hand, in the operation region where the heat load is low, it is possible to prevent the temperature of the catalyst device 10 from excessively decreasing and maintain an appropriate catalyst purification performance in the catalyst device 10, and to reduce exhaust energy due to excessively low exhaust gas temperature. As a result, it is possible to prevent the turbo response from deteriorating. Further, since the turbine cooling system 370 is provided as a separate system independently of the cooling system that cools the engine main body 2, the temperature of the cooling water circulating through the turbine cooling system 370 can be easily controlled, and the turbine cooling system 370. The temperature of the cooling water that circulates can be quickly set to an appropriate temperature according to the operating state of the engine 301.

  Furthermore, according to the engine 301 according to the embodiment of the present invention described above, the exhaust passage 4 includes the exhaust manifold 41 that introduces exhaust gas into the turbocharger 305, and the turbocharger 305 is introduced from the exhaust manifold 41. A turbine wheel 353 that is rotationally driven by the generated exhaust gas is accommodated in the turbine housing 354, and a compressor impeller 355 that is rotated when the turbine wheel 353 is rotationally driven includes a compressor 352 that is accommodated in the compressor housing 356. The exhaust gas introduction part 360 includes the exhaust manifold 41 and the turbine housing 354, and the water jacket 371 is provided in the turbine housing 354. Accordingly, since the water jacket 371 is provided in the turbine housing 354 that forms the exhaust gas introduction part 360, the exhaust gas introduced into the turbocharger 305 as the turbine housing 354 is cooled by the water jacket 371 based on the exhaust gas temperature. Can be cooled to an appropriate temperature.

  The internal combustion engine according to the above-described embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope described in the claims. In the above description, the water jacket 371 has been described as being provided on the scroll wall 364 (on the bearing portion 358 side), but may be provided so as to cover the entire turbine housing 354.

  6 is a schematic sectional view of an engine according to Embodiment 4 of the present invention, FIG. 7 is a flowchart showing a flow of turbine cooling control of the engine according to Embodiment 4 of the present invention, and FIG. 8 is an embodiment of the present invention. FIG. 9 is a flowchart showing the flow of the engine exhaust gas temperature lowering control according to the fourth embodiment of the present invention, FIG. 10 is a diagram showing the relationship between the engine speed of the engine according to FIG. FIG. 11 is a flowchart showing the flow of intake air increase control of the engine according to Embodiment 4 of the present invention, and FIG. 11 shows the air-fuel ratio and intake pipe pressure, ignition timing, turbine inlet exhaust gas of the engine according to Embodiment 4 of the present invention. It is a diagram which shows the relationship with temperature. The internal combustion engine according to the fourth embodiment has substantially the same configuration as the internal combustion engine according to the first embodiment, but differs from the internal combustion engine according to the first embodiment in that it includes a thermal load reducing unit. In addition, about the structure, effect | action, and effect which are common in the Example mentioned above, while overlapping description is abbreviate | omitted as much as possible, the same code | symbol is attached | subjected.

  The engine 401 as the internal combustion engine of the present embodiment includes a thermal load reduction unit 480 as a thermal load reduction unit. The thermal load reducing unit 480 can reduce the thermal load caused by the exhaust gas, and includes the injector 17, the ignition plug 18, and the wastegate valve 44 described above. That is, as described above, the injector 17 functions as the fuel supply means of the present invention capable of supplying fuel to the combustion chamber 13 of the engine body 2, and the spark plug 18 sucks fuel and intake in the combustion chamber 13 of the engine body 2. The waste gate valve 44 functions as an intake air amount adjusting unit of the present invention that adjusts the intake air amount sucked into the engine body 2.

  Then, the ECU 90 as the control means controls the thermal load reducing unit 480 when the cooling water temperature WT detected by the cooling water temperature sensor 95 is higher than the overheat avoidance temperature TW3 for avoiding overheating of the turbocharger 5 in advance. To reduce the heat load caused by the exhaust gas. In this embodiment, the ECU 90 controls the injector 17 to mix the fuel of the engine body 2 and the intake air when the coolant temperature WT is higher than the overheat avoidance temperature TW3 and equal to or lower than the overheat prevention temperature TW4. The air / fuel ratio of the engine is set to be leaner than the stoichiometric air / fuel ratio, the ignition plug 18 is controlled to set the ignition timing of the engine body 2 to the advance side, and the wastegate valve 44 is controlled to increase the supercharging pressure. The intake air amount sucked into the engine body 2 is set to the increase side.

  Here, in the first embodiment described above, the overheat avoidance temperature TW3 has been described as being set as a fixed threshold in advance according to the specifications of the engine 1 and the turbocharger 5, but in this embodiment, the engine speed is set. And is set according to the engine load. That is, the ECU 90 sets the overheat avoidance temperature TW3 based on the engine speed and the engine load detected by the crank angle sensor 91 as the rotation speed detection means and the throttle position sensor 92 as the load detection means, respectively. FIG. 8 is a diagram showing the relationship between the engine speed, the engine load, and the overheat avoidance temperature TW3, where the horizontal axis represents the engine speed and the vertical axis represents the engine load. As shown in FIG. 8, the ECU 90 stores the overheat avoidance temperature TW3 in advance in a storage unit (not shown) as a map in association with the engine speed and the engine load. Here, the overheat avoidance temperature TW3 is stored in association with the engine speed and the engine load so that [TW3-1> TW3-2> TW3-3> TW3-4].

  That is, in the engine 401, the exhaust heat capacity tends to increase on the high rotation / high load side, but the cooling capacity of the radiator 73 increases due to the relationship with the vehicle running wind and the like. Therefore, the overheat avoidance temperature TW3 is set to a relatively high value on the high rotation (high speed) / low load side according to the engine speed and the engine load, while on the low rotation (low speed) / high load side. Set to a relatively low value. As a result, in an operating state where overheating is more likely to occur, transition to overheating avoidance (03 control) is performed even when the cooling water temperature WT is relatively low, whereas in an operating state where overheating is difficult, the cooling water temperature WT is a relatively high temperature. Then, control is performed so as to shift to overheat avoidance (03 control). Then, the ECU 90 reads any one of TW3-1 to TW3-4 from this map based on the engine speed and the engine load, and sets it to the overheat avoidance temperature TW3 that is actually used for determination. Note that the warm normal state temperature TW1, the overheat prevention temperature TW2, and the overheat countermeasure temperature TW4 may be appropriately set according to the operating state of the engine 1 instead of a fixed value, similarly to the overheat avoidance temperature TW3.

  Next, the flow of turbine cooling control, exhaust gas temperature reduction control, and intake air increase control in the engine 1 will be described with reference to FIGS. In this turbine cooling control, as shown in FIG. 7, the ECU 90 first reads the engine speed and the engine load detected by the crank angle sensor 91 and the throttle position sensor 92, respectively (S300). Next, the ECU 90 reads any one of TW3-1 to TW3-4 from the map of FIG. 8 based on the engine speed and the engine load as the reference water temperature TW, and actually uses the overheat avoidance temperature TW3 used for the determination. (S302). At this time, the warm normal state temperature TW1, the overheat prevention temperature TW2, and the overheat countermeasure temperature TW4 are also set.

  Next, the ECU 90 detects and reads the cooling water temperature WT after the cooling water temperature sensor 95 cools the intake manifold forming the exhaust gas introduction unit 60 with the water jacket 71 (S304). Then, the ECU 90 compares the coolant temperature WT with the warm normal state temperature TW1 and determines whether the coolant temperature WT is higher than the warm normal state temperature TW1 (S306). When it is determined that the cooling water temperature WT is equal to or lower than the warm normal state temperature TW1 (S306: No), the drive of the electric water pump 74 and the electric fan 75 is controlled as a warm-up mode (00 control selection) to The water pump 74 and the electric fan 75 are set in a stopped state, and the process ends (S308). When it is determined that the coolant temperature WT is higher than the warm normal state temperature TW1 (S306: Yes), the ECU 90 compares the coolant temperature WT with the overheat prevention temperature TW2, and the coolant temperature WT is overheat prevention temperature TW2. It is determined whether or not it is higher (S310). When it is determined that the cooling water temperature WT is equal to or lower than the overheat prevention temperature TW2 (S310: No), the ECU 90 controls the driving of the electric water pump 74 and the electric fan 75 as a normal mode (01 control selection) to While the fan 75 is stopped, the control of the electric water pump 74 is set to a control mode based on the second catalyst inlet exhaust gas temperature GT detected by the second catalyst inlet exhaust gas temperature sensor 94, and the process ends (S312). .

  When it is determined that the coolant temperature WT is higher than the overheat prevention temperature TW2 (S310: Yes), the ECU 90 compares the coolant temperature WT with the overheat avoidance temperature TW3, and the coolant temperature WT is higher than the overheat avoidance temperature TW3. It is determined whether or not (S314). When it is determined that the cooling water temperature WT is equal to or lower than the overheat avoidance temperature TW3 (S314: No), the ECU 90 controls the drive of the electric water pump 74 and the electric fan 75 to prevent overheating (02 control selection), and The operation of the fan 75 is started, and the electric water pump 74 is ended by increasing the operation output regardless of the second catalyst inlet exhaust gas temperature GT (S316).

  When it is determined that the coolant temperature WT is higher than the overheat avoidance temperature TW3 (S314: Yes), the ECU 90 compares the coolant temperature WT with the overheat countermeasure temperature TW4, and the coolant temperature WT is higher than the overheat countermeasure temperature TW4. It is determined whether or not (S318). When it is determined that the cooling water temperature WT is equal to or lower than the overheat countermeasure temperature TW4 (S318: No), the ECU 90 controls the driving of the electric water pump 74 and the electric fan 75 to avoid overheating (03 control selection), and The operation output of the fan 75 and the electric water pump 74 is increased to the maximum (S320), exhaust gas temperature lowering control (S322) and intake air increase control (S324) are executed, and the process is terminated.

  Here, in the exhaust gas temperature lowering control of S322, the ECU 90 determines whether or not to execute the exhaust gas temperature lowering control as shown in FIG. 9 (S400). The determination as to whether or not to execute the exhaust gas temperature lowering control may be made using the determination result regarding whether or not the coolant temperature WT in S314 (see FIG. 7) is higher than the overheat avoidance temperature TW3. If it is determined not to execute the exhaust gas temperature lowering control (S400: No), this control is terminated as it is. If it is determined that the exhaust gas temperature lowering control is to be executed (S400: Yes), the ECU 90 controls the injector 17 so that the excess air ratio λ = 1, that is, the fuel injected from the injector 17 and the intake air Feedback control for setting the air-fuel ratio of the mixed gas to the stoichiometric air-fuel ratio is stopped (S402). Then, the ECU 90 reads the fuel amount Qλ (hereinafter abbreviated as “λ1 operating fuel amount Qλ”) in the operation with the excess air ratio λ = 1 determined from the engine speed, the engine load, and the like (S404). The fuel amount reduced by multiplying the λ1 operating fuel amount Qλ by a leaning coefficient corresponding to a preset lean operation degree is calculated and set, and the fuel injection amount by the injector 17 is controlled to control the air-fuel ratio of the mixture Is set to be leaner than the stoichiometric air-fuel ratio (S406). Further, the ECU 90 calculates and sets the ignition timing SA advanced by multiplying the ignition timing SA by the spark plug 18 by a leaning coefficient corresponding to a preset lean operation degree, The ignition timing SA by the plug 18 is controlled to set the ignition timing SA to the advance side, and the process ends (S408). As a result, the amount of heat generated in the engine body 2 can be reduced by setting the air-fuel ratio to be leaner than the stoichiometric air-fuel ratio, and the output by leaning can be achieved by setting the ignition timing SA to the advance angle side. (TRQ) A decrease can be minimized. If the cooling water temperature WT does not fall below the predetermined temperature, here, the overheat avoidance temperature TW3, even when the exhaust gas temperature lowering control is executed, the leaning coefficient is changed stepwise (see FIG. 11 described later). What is necessary is just to control so that the lean operation degree may be strengthened.

  In the intake air increase control in S324, the ECU 90 first determines whether or not supercharging pressure upper limit control such as limiting the amount of exhaust gas introduced into the turbine 51 is being executed as shown in FIG. 10 (S500). ). When it is determined that the supercharging pressure upper limit control is not being executed (S500: No), this control is terminated as it is. When it is determined that the supercharging pressure upper limit control is being executed (S500: Yes), the ECU 90 sets the supercharging pressure temporarily high by multiplying the supercharging pressure upper limit value by a preset up factor, and the waist The gate valve 44 is controlled to reduce the opening degree of the waste gate valve 44 to an opening degree corresponding to the increase in the supercharging pressure (S502). As a result, by controlling the wastegate valve 44 to increase the supercharging pressure and setting the intake air amount sucked into the engine body 2 to the increase side, it is possible to further suppress the output (TRQ) decrease due to leaning. it can.

11, in the engine 401, is a diagram showing an air-fuel ratio A / F intake pipe pressure MV, the ignition timing SA, an example of the relationship between the turbine 51 inlet exhaust gas temperature _{T in} under equal torque (TRQ constant) . As described above, the injector 17 is controlled to set the air / fuel ratio of the fuel / intake air mixture in the engine body 2 to be leaner than the stoichiometric air / fuel ratio, thereby reducing the amount of heat generated in the engine body 2 and ignition. The plug 18 is controlled to set the ignition timing of the engine body 2 to the advance side, and the wastegate valve 44 is controlled to increase the supercharging pressure and set the intake air amount sucked into the engine body 2 to the increase side. substantially even when kept constant, it can be understood that it is possible to sufficiently lower the turbine 51 inlet exhaust gas temperature T _in the torque by.

  Returning to FIG. 7 again, when it is determined that the coolant temperature WT is higher than the overheat countermeasure temperature TW4 (S318: Yes), the ECU 90 decreases the opening of the throttle valve 8 as an overheat countermeasure (04 control selection). At the same time, by increasing the opening degree of the wastegate valve 44 and reducing the supercharging pressure, the output of the engine body 2 is lowered, and the temperature of the exhaust gas discharged from the engine body 2 itself is lowered and the process ends (S326). ).

  According to the engine 401 according to the embodiment of the present invention described above, the exhaust gas introduction unit 60 that introduces exhaust gas into the turbocharger 5 is cooled by the turbine cooling system 70 independent of the cooling system that cools the engine body 2. At the same time, since the cooling water flow rate of the turbine cooling system 70 is adjusted based on the temperature of the exhaust gas introduced into the second catalyst 10b of the catalyst device 10, it is possible to reliably prevent overheating in an operation region where the heat load is high. it can. On the other hand, in the operation region where the heat load is low, it is possible to prevent the temperature of the catalyst device 10 from excessively decreasing and maintain an appropriate catalyst purification performance in the catalyst device 10, and to reduce exhaust energy due to excessively low exhaust gas temperature. As a result, it is possible to prevent the turbo response from deteriorating. Further, since the turbine cooling system 70 is provided as a separate system independently of the cooling system for cooling the engine body 2, the temperature of the cooling water circulating in the turbine cooling system 70 can be easily controlled, and the turbine cooling system 70 The temperature of the cooling water circulating through the engine can be quickly set to an appropriate temperature according to the operating state of the engine 1.

  Furthermore, the engine 401 according to the embodiment of the present invention described above includes the thermal load reducing unit 480 that can reduce the thermal load due to the engine body 2, and the ECU 90 detects the cooling water detected by the cooling water temperature sensor 95. When the temperature WT is higher than the overheat avoidance temperature TW3 for avoiding overheating of the turbocharger 5 in advance, the thermal load reduction unit 480 is controlled to reduce the heat load due to the exhaust gas. Therefore, since the thermal load can be reduced on the engine body 2 side by the thermal load reducing unit 480 in a state just before overheating although the turbocharger 5 has not yet overheated, the temperature of the exhaust gas can be lowered, Thereby, overheating of the turbocharger 5 can be reliably prevented.

  Furthermore, according to the engine 401 according to the embodiment of the present invention described above, the thermal load reducing unit 480 includes the injector 17 capable of supplying fuel to the combustion chamber 13 of the engine body 2, and the ECU 90 includes cooling water. When the cooling water temperature WT detected by the temperature sensor 95 is higher than the overheat avoidance temperature TW3, the injector 17 is controlled so that the air-fuel ratio of the mixture of fuel and intake air of the engine body 2 is leaner than the stoichiometric air-fuel ratio. Set. Therefore, the amount of heat generated in the engine body 2 can be reliably reduced by setting the air-fuel ratio to be leaner than the stoichiometric air-fuel ratio in a state just before overheating although the turbocharger 5 has not yet overheated.

  Furthermore, according to the engine 401 according to the embodiment of the present invention described above, the thermal load reducing unit 480 has the spark plug 18 that ignites the mixture of fuel and intake air in the combustion chamber 13 of the engine body 2. When the coolant temperature WT detected by the coolant temperature sensor 95 is higher than the overheat avoidance temperature TW3, the ECU 90 controls the spark plug 18 to set the ignition timing of the engine body 2 to the advance side. Therefore, even when the air / fuel ratio is set to be leaner than the stoichiometric air / fuel ratio when the turbocharger 5 has not yet overheated but is about to overheat, by setting the ignition timing to the advance side, Output reduction due to leaning can be suppressed to a minimum, and fuel consumption deterioration can also be suppressed.

  Furthermore, according to the engine 401 according to the embodiment of the present invention described above, the thermal load reduction unit 480 includes the wastegate valve 44 that adjusts the intake air amount sucked into the engine body 2, and the ECU 90 includes: When the coolant temperature WT detected by the coolant temperature sensor 95 is higher than the overheat avoidance temperature TW3, the wastegate valve 44 is controlled to set the intake air amount sucked into the engine body 2 to the increase side. Therefore, even if the turbocharger 5 has not yet overheated, but the air-fuel ratio is set to be leaner than the stoichiometric air-fuel ratio in a state just before overheating, the supercharging pressure is increased by controlling the wastegate valve 44 to increase the supercharging pressure. By setting the intake air amount sucked into the increase side, it is possible to further suppress the output decrease due to leaning.

  Furthermore, according to the engine 401 according to the embodiment of the present invention described above, the crank angle sensor 91 for detecting the engine speed of the engine body 2 and the throttle position sensor 92 for detecting the engine load of the engine body 2 are provided. The ECU 90 sets the overheat avoidance temperature TW3 based on the engine speed detected by the crank angle sensor 91 and the engine load detected by the throttle position sensor 92. Therefore, in an operation state in which overheating is likely to occur, transition to overheating is avoided even when the cooling water temperature WT is relatively low. In an operation state in which overheating is difficult, overheating is avoided after the cooling water temperature WT becomes relatively high. Therefore, overheating can be reliably avoided, and the air-fuel ratio can be prevented from being set to the lean side unnecessarily. It can be minimized. As a result, it is possible to prevent the exhaust purification performance from deteriorating.

  The internal combustion engine according to the above-described embodiment of the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope described in the claims. In the above description, the intake air amount adjusting means has been described as being the waste gate valve 44. However, the throttle valve 8 may be configured if there is a margin in the upper limit opening of the throttle valve 8.

  As described above, the internal combustion engine according to the present invention can reliably prevent overheating and maintain catalyst purification performance, and is applied to various internal combustion engines equipped with a supercharger. Is preferred.

It is a schematic sectional drawing of the engine which concerns on Example 1 of this invention. It is a flowchart which shows the flow of the turbine cooling control of the engine which concerns on Example 1 of this invention. It is a diagram which shows the relationship between the 2nd catalyst inlet exhaust gas temperature of the engine which concerns on Example 1 of this invention, and the control current of an electric water pump. It is a flowchart which shows the flow of the 1st catalyst bypass stop control of the engine which concerns on Example 2 of this invention. It is a schematic sectional drawing which shows the structure of the principal part of the turbocharger with which the engine which concerns on Example 3 of this invention is provided. It is a schematic sectional drawing of the engine which concerns on Example 4 of this invention. It is a flowchart which shows the flow of the turbine cooling control of the engine which concerns on Example 4 of this invention. It is a diagram which shows the relationship between the engine speed of the engine which concerns on Example 4 of this invention, an engine load, and overheat avoidance temperature. It is a flowchart which shows the flow of the exhaust gas temperature fall control of the engine which concerns on Example 4 of this invention. It is a flowchart which shows the flow of the intake air increase control of the engine which concerns on Example 4 of this invention. It is a diagram which shows an example of the relationship between the air fuel ratio of the engine which concerns on Example 4 of this invention, an intake pipe pressure, ignition timing, and turbine inlet exhaust gas temperature.

Explanation of symbols

1, 201, 301, 401 Engine (Internal combustion engine)
2 Engine body (Internal combustion engine body)
3 Intake passage 4 Exhaust passage 5, 305 Turbocharger (supercharging means)
8 Throttle valve 10 Catalyst device 10a First catalyst 10b Second catalyst 11 Piston 12 Cylinder bore 13 Combustion chamber 15 Intake port 16 Exhaust port 17 Injector (fuel supply means)
18 Spark plug (ignition means)
19 Crankshaft 41 Exhaust manifold (exhaust introduction passage)
42 Exhaust pipe 43 Wastegate passage 44 Wastegate valve (intake air amount adjusting means)
45 Bypass passage 46 First catalyst passage 47 Flow path control valve (flow path control means)
51, 351 Turbine 52, 352 Compressor 53, 353 Turbine wheel 54, 354 Turbine housing 55, 355 Compressor impeller 56, 356 Compressor housing 57, 357 Rotor shaft 60, 360 Exhaust gas introduction part 70, 370 Turbine cooling system (supercharging means) Cooling system)
71,371 Water jacket (exhaust gas inlet cooling means)
72,372 Cooling water circulation passage (cooling medium passage)
73, 373 Radiator 74, 374 Electric water pump (flow rate adjusting means)
75, 375 Electric fan (radiator cooling means)
90 ECU (control means)
91 Crank angle sensor (rotational speed detection means)
92 Throttle position sensor (load detection means)
93 A / F sensor 94 Second catalyst inlet exhaust gas temperature sensor (exhaust gas temperature detection means)
95 Cooling water temperature sensor (cooling medium temperature detection means)
364 Scroll Wall 480 Thermal Load Reduction Unit (thermal load reduction means)

Claims (9)

Exhaust gas exhaust from the internal combustion engine body, and an exhaust passage having a catalyst for purifying the exhaust gas;
Supercharging means for compressing and supercharging the intake air to the internal combustion engine body by being driven by the exhaust gas introduced through an exhaust gas introduction unit;
An exhaust gas introduction part cooling means capable of cooling the exhaust gas introduction part by a cooling medium; and a cooling medium capable of circulating the cooling medium to the exhaust gas introduction part cooling means independently of a cooling system for cooling the internal combustion engine body. Cooling means cooling comprising a passage, a radiator capable of cooling the cooling medium circulating in the cooling medium passage, and a flow rate adjusting means capable of adjusting a flow rate of the cooling medium supplied to the exhaust gas introduction portion cooling means. The system,
Exhaust gas temperature detecting means for detecting the temperature of the exhaust gas introduced into the catalyst;
Control means for controlling the flow rate adjusting means based on the temperature of the exhaust gas detected by the exhaust gas temperature detecting means,
Internal combustion engine. The exhaust passage has an exhaust introduction passage for introducing the exhaust gas into the supercharging means,
The supercharging means includes a turbine in which a wheel that is rotationally driven by exhaust gas introduced from the exhaust introduction passage is accommodated in a turbine housing, and a compressor in which an impeller that is rotated when the wheel is rotationally driven is accommodated in a compressor housing. And
The exhaust gas introduction part is configured to include the exhaust introduction passage and the turbine housing,
The exhaust gas introduction part cooling means is provided in at least one of the exhaust introduction passage and the turbine housing,
The internal combustion engine according to claim 1. The catalyst has a first catalyst and a second catalyst provided downstream of the first catalyst with respect to the exhaust direction of the exhaust gas,
The exhaust passage has a bypass passage in which the exhaust gas can bypass the first catalyst, and a flow path control means capable of regulating the flow of the exhaust gas to the bypass passage,
The exhaust gas temperature detecting means detects the temperature of the exhaust gas introduced into the second catalyst,
The control means controls the flow path control means to regulate the flow of the exhaust gas to the bypass passage when the temperature of the exhaust gas is lower than a preset bypass regulation temperature,
The internal combustion engine according to claim 1 or 2. Radiator cooling means capable of cooling the radiator;
Cooling medium temperature detecting means for detecting the temperature of the cooling medium after cooling the exhaust gas introduction part,
The control means controls the radiator cooling means and the flow rate adjusting means stepwise based on the temperature of the cooling medium detected by the cooling medium temperature detecting means.
The internal combustion engine according to any one of claims 1 to 3. A heat load reducing means capable of reducing the heat load by the internal combustion engine body,
The control means controls the thermal load reducing means when the temperature of the cooling medium detected by the cooling medium temperature detecting means is higher than an overheat avoidance temperature for avoiding overheating of the supercharging means in advance. The thermal load caused by the exhaust gas is reduced,
The internal combustion engine according to claim 4. The thermal load reducing means has fuel supply means capable of supplying fuel to a combustion chamber of the internal combustion engine body,
When the temperature of the cooling medium detected by the cooling medium temperature detection means is higher than the overheat avoidance temperature, the control means controls the fuel supply means to mix the fuel of the internal combustion engine body and the intake air The air-fuel ratio of the gas is set to be leaner than the theoretical air-fuel ratio,
The internal combustion engine according to claim 5. The thermal load reducing means includes ignition means for igniting a mixture of fuel and intake air in a combustion chamber of the internal combustion engine body,
The control means controls the ignition means to set the ignition timing of the internal combustion engine body to an advance side when the temperature of the cooling medium detected by the cooling medium temperature detection means is higher than the overheat avoidance temperature. It is characterized by
The internal combustion engine according to claim 5 or 6. The thermal load reducing means includes intake air amount adjusting means for adjusting an intake air amount sucked into the internal combustion engine body,
The control means controls the intake air amount adjusting means when the temperature of the cooling medium detected by the cooling medium temperature detecting means is higher than the overheat avoidance temperature, and the intake air sucked into the internal combustion engine body The amount is set to the increasing side,
The internal combustion engine according to any one of claims 5 to 7. Rotation speed detection means for detecting the rotation speed of the internal combustion engine body;
Load detecting means for detecting a load of the internal combustion engine body,
The control means sets the overheat avoidance temperature based on the rotation speed of the internal combustion engine body detected by the rotation speed detection means and the load of the internal combustion engine body detected by the load detection means.
The internal combustion engine according to any one of claims 5 to 8.

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