Vehicle control system

Abstract

This promotes the warm-up of the exhaust gas purification catalyst. [Solution] A vehicle control device for controlling a hybrid vehicle comprising an engine having an exhaust gas purification catalyst and an exhaust throttle valve located downstream of the exhaust gas purification catalyst in the exhaust passage, and a motor capable of motorizing the engine, comprising a control unit that, when there is no request to start the engine, performs control to raise the temperature of the exhaust gas purification catalyst by fully closing the exhaust throttle valve and motoring the engine in accordance with the temperature in the exhaust passage being below a predetermined temperature.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a vehicle control device.

BACKGROUND ART

[0002] It is known to control the engine and the motor so that when engine startup is predicted and the engine coolant temperature is lower than a threshold value, the engine is cranked by the motor to warm up the engine before the engine is started (see, for example, Patent Document 1).

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0003]

PATENT DOCUMENT 1

PATENT DOCUMENT 2

PATENT DOCUMENT 3

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] An object of the present disclosure is to promote warm-up of an exhaust purification catalyst.

MEANS FOR SOLVING THE PROBLEMS

[0005] One aspect of the present disclosure is a vehicle control device that controls a hybrid vehicle including an engine having an exhaust purification catalyst in an exhaust passage and an exhaust throttle valve disposed downstream of the exhaust purification catalyst, and a motor capable of cranking the engine, the vehicle control device including a control unit that executes control to increase the temperature of the exhaust purification catalyst by fully closing the exhaust throttle valve and performing cranking in response to the temperature in the exhaust passage being lower than a predetermined temperature when there is no request to start the engine. [Effects of the Invention]

[0006] According to this disclosure, the warm-up of the exhaust gas purification catalyst can be accelerated. [Brief explanation of the drawing]

[0007] [Figure 1] This is a diagram showing the schematic configuration of a vehicle according to the first embodiment. [Figure 2] This is a flowchart showing the control flow in the ECU according to the first embodiment. [Figure 3] This is a diagram showing the schematic configuration of a vehicle according to the second embodiment. [Figure 4] This is a flowchart showing the control flow in the ECU according to the second embodiment. [Modes for carrying out the invention]

[0008] Exhaust gas purification systems using precious metal catalysts require warming up to a predetermined temperature, which is generally achieved by the heat of the incoming exhaust gas. Numerous techniques have been proposed to accelerate the warming-up of such exhaust gas purification systems by increasing the exhaust gas temperature. For example, a known technique involves completely closing an exhaust throttle valve located in the exhaust passage downstream of the catalyst, thereby increasing the exhaust gas temperature due to the increased engine load caused by the rise in back pressure. In addition, another known technique involves controlling a low-pressure EGR valve downstream of the exhaust throttle valve to open it, thereby recirculating the high-temperature EGR gas and increasing the exhaust gas temperature. However, before the exhaust gas purification system is fully warmed up, unpurified exhaust gas passes through the catalyst, and therefore enters the catalyst before warming up is complete. Controlling the concentration and flow rate of hazardous substances is also important.

[0009] Conventional methods of generating heat through combustion result in exhaust gases containing harmful substances such as NOx and HC. To reduce the concentration of these harmful substances, technologies for generating heat by means other than combustion, such as using a dedicated electric heating device, are known. However, dedicated electric heating devices are expensive and have the disadvantage of complex system configurations. Another known example is a technology that compresses the air in the cylinder by motoring and controls the valve timing to efficiently extract the heat. However, this technology has the problem that the gas temperature decreases because the compressed air in the cylinder undergoes an expansion stroke before being discharged and also expands when passing through the exhaust valve. Therefore, the vehicle control device according to this disclosure generates heat by compressing the air in the exhaust passage through motoring while the engine is stopped, in order to suppress the release of harmful substances into the atmosphere, and supplies heat to the exhaust purification device without the temperature decrease caused by expansion.

[0010] Specifically, a vehicle control device, which is one aspect of this disclosure, is a vehicle control device for controlling a hybrid vehicle comprising an engine having an exhaust gas purification catalyst and an exhaust throttle valve located downstream of the exhaust gas purification catalyst in the exhaust passage, and a motor capable of motorizing the engine. The hybrid vehicle is a PHEV (Plug-in Hybrid Electric Vehicle). and HEV (Hybrid Electric Vehicle). Exhaust purification catalysts are catalysts that require warming up. It has the function of sufficiently purifying harmful components in the exhaust gas above its activation temperature. The exhaust throttle valve adjusts the flow rate of the exhaust gas. The motor can motorize the engine, for example, by rotating the engine's output shaft when no fuel is being supplied to the engine. When motoring is performed, air is discharged from the engine into the exhaust passage.

[0011] The vehicle's control device includes a control unit that, when there is no request to start the engine, performs motoring by fully closing the exhaust throttle valve in accordance with the temperature in the exhaust passage being below a predetermined temperature, thereby raising the temperature of the exhaust purification catalyst. "When there is no request to start the engine" may also mean when there is no need to start the engine. The control unit may determine that there is a request to start the engine when it becomes necessary to start the engine. When there is no request to start the engine, fuel is not supplied to the engine. When there is no request to start the engine, the engine can be motored by the motor. At this time, by fully closing the exhaust throttle valve and performing motoring, the pressure in the exhaust passage upstream of the exhaust throttle valve increases. As a result, the temperature in the exhaust passage upstream of the exhaust throttle valve increases. The temperature in the exhaust passage may be the temperature of the exhaust gas, or it may be the temperature of the exhaust purification catalyst. By raising the temperature in the exhaust passage in accordance with the temperature in the exhaust passage being below a predetermined temperature, the temperature in the exhaust passage can be raised to above the predetermined temperature. The predetermined temperature is, for example, the temperature at which the exhaust purification catalyst is activated. In other words, by performing motoring with the exhaust throttle valve fully closed, it becomes possible to warm up the exhaust catalytic converter before starting the engine.

[0012] Furthermore, the phrase "when there is no request to start the engine" may include situations where there is no current request to start the engine, but it is predicted that the need to start the engine will arise in the near future. In other words, it may also include situations where the engine is expected to be started in the near future. For example, when the battery charge level approaches the threshold for starting the engine, it may be determined that the engine will be started in the near future. This would prevent unnecessary warm-up of the exhaust gas purification catalyst.

[0013] Furthermore, when the control unit is performing control to raise the temperature of the exhaust gas purification catalyst, it may control the opening degree of the exhaust throttle valve so that the pressure upstream of the exhaust throttle valve is below a predetermined pressure. The predetermined pressure is the upper limit of the pressure at which no problems occur in the exhaust passage. These problems include component damage due to pressure and exhaust leaks. In other words, when the pressure in the exhaust passage upstream of the exhaust throttle valve is high, controlling the exhaust throttle valve to the open side can reduce the pressure in the exhaust passage, thereby suppressing the occurrence of pressure-related problems in the exhaust passage.

[0014] Furthermore, the control unit may open the exhaust throttle valve and terminate the motoring in response to a request to start the engine. In this way, the engine can be started immediately when a request to start the engine is made. It is possible that the temperature of the exhaust purification catalyst may not be sufficiently high at this time, but since the engine is started when the temperature of the exhaust purification catalyst is at a certain level, the exhaust purification catalyst can be activated more quickly.

[0015] Furthermore, the engine may further include an EGR passage connecting the exhaust passage and the intake passage upstream of the exhaust throttle valve, and an EGR valve for adjusting the cross-sectional area of ​​the EGR passage. The control unit may, when there is no request to start the engine, fully close the exhaust throttle valve and perform motoring in accordance with the fact that the wall temperature of the intake passage is lower than a predetermined wall temperature. The control unit may also control the EGR valve to open if the pressure in the exhaust passage upstream of the exhaust throttle valve becomes higher than a predetermined pressure, or if the temperature in the exhaust passage upstream of the exhaust throttle valve becomes higher than a second predetermined temperature.

[0016] The predetermined pressure is the upper limit value of the pressure at which no problem occurs in the exhaust passage. Such problems include damage to components due to pressure, exhaust gas leakage, and the like. That is, when the pressure in the exhaust passage upstream of the exhaust throttle valve is high, the pressure in the exhaust passage can be reduced by controlling the EGR valve to the open side, so that the occurrence of pressure-related problems in the exhaust passage can be suppressed. The wall surface temperature of the intake passage may be the temperature of a component to be heated, or may be the temperature of a specific component of the engine. Further, the second predetermined temperature is a temperature at which the temperature of the component provided in the intake system or the inside of the engine can be raised to the warm-up completion temperature. When the temperature in the exhaust passage upstream of the exhaust throttle valve is high, high-temperature gas can be supplied to the intake passage by controlling the EGR valve to the open side. Thereby, the temperature of the components provided in the intake passage and the inside of the engine can be increased before the engine is started.

[0017] Further, even after the control unit controls the EGR valve to the open side, when the pressure in the exhaust passage upstream of the exhaust throttle valve is higher than the predetermined pressure, the control unit may control the exhaust throttle valve to the open side. If the pressure in the exhaust passage does not decrease sufficiently even after the EGR valve is controlled to the open side, the control unit controls the exhaust throttle valve to the open side to reduce the pressure in the exhaust passage. Thereby, the occurrence of pressure-related problems in the exhaust passage can be suppressed.

[0018] Note that the vehicle control device according to the present disclosure is An engine having an exhaust passage provided with an exhaust purification catalyst and an exhaust throttle valve disposed downstream of the exhaust purification catalyst, an EGR passage that communicates the exhaust passage upstream of the exhaust throttle valve with the intake passage, and an EGR valve that adjusts the passage cross-sectional area of the EGR passage, a motor capable of motoring the engine, A vehicle control device for controlling a hybrid vehicle comprising When there is no request to start the engine, in response to the fact that the wall surface temperature of the intake passage is lower than a predetermined wall surface temperature, the exhaust throttle valve is fully closed to perform the motoring, When the pressure in the exhaust passage upstream of the exhaust throttle valve becomes higher than a predetermined pressure, or when the temperature in the exhaust passage upstream of the exhaust throttle valve reaches or exceeds a second predetermined temperature, a control unit is provided that controls the EGR valve to the open side, This may be a control device for a vehicle.

[0019] Further, the control unit may control the exhaust throttle valve to the open side when the pressure in the exhaust passage upstream of the exhaust throttle valve is higher than the predetermined pressure even after controlling the EGR valve to the open side.

[0020] Further, the control unit may execute opening the exhaust throttle valve, closing the EGR valve, and terminating motoring in response to a request to start the engine.

[0021] Hereinafter, embodiments for carrying out this disclosure will be described in detail by way of example with reference to the drawings. However, unless otherwise specifically stated, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of this disclosure only to those aspects.

[0022] <First Embodiment> Figure 1 is a diagram showing a schematic configuration of a vehicle 10 according to the first embodiment. The vehicle 10 is a hybrid vehicle having an engine 1 and a motor 2, such as a PHEV (Plug-in Hybrid Electric Vehicle) or a HEV (Hybrid Electric Vehicle). The engine 1 shown in Figure 1 is, for example, an engine having four cylinders 11. The engine 1 may be, for example, either a gasoline engine or a diesel engine. The engine 1 is an example of an internal combustion engine. The motor 2 can rotate the output shaft (that is, the crankshaft) of the engine 1 by supply of electric power.

[0023] Furthermore, the engine 1 is connected to an intake passage 3 and an exhaust passage 4. The intake passage 3 is equipped with an airflow meter 31 that outputs a signal corresponding to the flow rate of air circulating within the intake passage 3. The amount of intake air for the engine 1 is measured by this airflow meter 31. Downstream of the airflow meter 31, the intake passage 3 is equipped with an intake throttle valve 32 that adjusts the flow rate of intake air circulating within the intake passage 3. This intake throttle valve 32 is opened and closed by an electric actuator to adjust the cross-sectional area of ​​the intake passage 3. A fuel injector 12 for injecting fuel is located in each of the intake passages 3 leading to each cylinder 11 of the engine 1.

[0024] Furthermore, a catalyst casing 40 is provided in the exhaust passage 4. A catalyst 41 is arranged inside the catalyst casing 40. The catalyst 41 may be, for example, a DOC (oxidation catalyst), a TWC (three-way catalyst), an SCR (selective reduction type NOx catalyst), an SCRF (filter supported by an SCR catalyst), or an NSR (storage reduction type NOx catalyst). The catalyst 41 exhibits sufficient exhaust gas purification capacity above its activation temperature. Note that the catalyst and filter arranged inside the catalyst casing 40 are not limited to these. The catalyst casing 40 is equipped with an exhaust gas temperature sensor 42 for detecting the temperature of the exhaust gas and an exhaust gas pressure sensor 43 for detecting the pressure of the exhaust gas. Downstream of the catalyst casing 40 in the exhaust passage 4, an exhaust throttle valve 44 is provided to adjust the flow rate of the exhaust gas circulating in the exhaust passage 4. This exhaust throttle valve 44 is opened and closed by an electric actuator to adjust the cross-sectional area of ​​the exhaust passage 4.

[0025] An electronic control unit (ECU) 100 is connected to the engine 1. The ECU 100 comprises a control unit 110 and a storage unit 120. The control unit 110 can be implemented by a hardware processor such as a CPU. The control unit 110 may also include RAM, ROM, cache memory, etc. The storage unit 120 is a means for storing information and is composed of a storage medium such as RAM or flash memory. The storage unit 120 stores programs executed by the control unit 110, data used by said programs, etc. The control unit 110 of the ECU 100 responds to the operating conditions of the engine 1 and the driver's requests. This controls engine 1.

[0026] Furthermore, the above-mentioned sensors are connected to the ECU 100 via electrical wiring, and the output signals from these sensors are input to the ECU 100. In addition, the motor 2, fuel injector 12, intake throttle valve 32, and exhaust throttle valve 44 are connected to the ECU 100 via electrical wiring, and the control unit 110 of the ECU 100 controls the motor 2, fuel injector 12, intake throttle valve 32, and exhaust throttle valve 44.

[0027] Furthermore, when there is no request to operate the engine 1 and the catalyst 41 is not activated, the control unit 110 rotates the crankshaft of the engine 1 with the motor 2 without supplying fuel to the engine 1. At this time, the control unit 110 closes the exhaust throttle valve 44. As a result, the control unit 110 expels air from the engine 1 and compresses the air in the exhaust passage 4 upstream of the exhaust throttle valve 44. Because the air temperature rises due to the compression of the air, the control unit 110 can raise the temperature of the catalyst 41.

[0028] Figure 2 is a flowchart showing the control flow in the ECU 100 according to the first embodiment. The routine shown in Figure 2 is repeatedly executed in the ECU 100 at predetermined time intervals. In step S101, the control unit 110 determines whether the engine start request is ON or OFF. The engine start request is ON when it is necessary to start engine 1 and OFF when it is not necessary to start engine 1. For example, if the remaining charge of the battery that supplies power to motor 2 falls below a threshold, the engine start request is ON in order to charge the battery. Also, for example, if the speed of vehicle 10 becomes equal to or greater than the starting speed of engine 1, the engine start request is ON in order to increase the driving force of vehicle 10. Here, if engine 1 is operating, the control unit 110 cannot motor engine 1. In other words, the engine start request being OFF is one of the conditions for motoring. If the control unit 110 makes a positive determination in step S101, the process proceeds to step S102.

[0029] In step S102, the control unit 110 fully opens the exhaust throttle valve 44. The control unit 110 fully opens the exhaust throttle valve 44 to release the exhaust gas produced when the engine 1 is operating into the atmosphere. The opening degree of the exhaust throttle valve 44 may be adjusted depending on the state of the engine 1 and the vehicle 10. For example, the exhaust throttle valve 44 may be controlled to the closed side in order to increase the load on the engine 1 while the engine 1 is operating. Once the process in step S102 is completed, the process proceeds to step S103.

[0030] In step S103, the control unit 110 turns off the motoring request. The motoring request is a request to motor engine 1. When the motoring request is OFF, the control unit 110 does not motor engine 1. Once the processing in step S103 is complete, this routine terminates.

[0031] Furthermore, if the control unit 110 determines that the condition is not met in step S101, the process proceeds to step S104. In step S104, the control unit 110 determines whether the exhaust temperature TC is equal to or greater than a predetermined temperature TCT. The control unit 110 obtains the exhaust temperature TC from the exhaust temperature sensor 42. As another example, the control unit 110 may estimate the exhaust temperature TC from the intake air temperature and exhaust pressure. Alternatively, a sensor that detects the floor temperature of the catalyst 41 may be used instead of the exhaust temperature sensor 42. The predetermined temperature TCT may be the activation temperature of the catalyst 41, or it may be the exhaust temperature required to activate the catalyst 41. If the exhaust temperature TC is equal to or greater than the predetermined temperature TCT, there is no need to motor the engine 1. Here, since motoring more than necessary is undesirable as it reduces the battery charge level, one of the conditions for motoring is that the exhaust temperature TC is less than the predetermined temperature TCT. If the control unit 110 determines that the result is positive, the process proceeds to step S102; if it determines that the result is negative, the process proceeds to step S105.

[0032] In step S105, the control unit 110 determines whether the exhaust pressure PC is higher than a predetermined pressure PCMX. The control unit 110 obtains the exhaust pressure PC from the exhaust pressure sensor 43. As another example, the control unit 110 may estimate the exhaust pressure PC from the intake air temperature and the rotational speed of the engine 1 accumulated from the start of motoring. Furthermore, as yet another example, the control unit 110 may estimate the exhaust pressure PC from the magnitude of the reaction force that the motor 2 receives when the motor 2 drives the engine 1. Here, if the exhaust pressure PC becomes too high, there is a risk that components such as the catalytic converter casing 40 located in the exhaust passage 4 may be damaged, or exhaust gas may leak from the components located in the exhaust passage 4. Therefore, the control unit 110 controls the exhaust throttle valve 44 so that the exhaust pressure PC is less than the predetermined pressure PCMX. For this reason, the predetermined pressure PCMX is the upper limit of the exhaust pressure at which damage to components located in the exhaust passage 4 is suppressed and exhaust gas leakage is suppressed. The predetermined pressure PCMX may be determined by experimentation or simulation and stored in the memory unit 120. If the control unit 110 makes a positive determination in step S105, the process proceeds to step S106.

[0033] In step S106, the control unit 110 increases the opening of the exhaust throttle valve 44 beyond its current opening. This reduces the exhaust pressure upstream of the exhaust throttle valve 44. The opening of the exhaust throttle valve 44 may be adjusted according to the state of the engine 1 and the vehicle 10. As another example, the control unit 110 may also use feedback control to adjust the opening of the exhaust throttle valve 44 based on the value detected by the exhaust pressure sensor 43 so that the exhaust pressure PC is less than or equal to a predetermined pressure PCMX. Once the processing in step S106 is completed, the process proceeds to step S107.

[0034] In step S107, the control unit 110 turns on the motoring request. This initiates motoring of engine 1. Once the processing in step S107 is complete, this routine terminates.

[0035] On the other hand, if the control unit 110 determines that the condition is negative in step S105, the process proceeds to step S108. In step S108, the control unit 110 completely closes the exhaust throttle valve 44. This causes the exhaust pressure upstream of the exhaust throttle valve 44 to rise rapidly. The opening degree of the exhaust throttle valve 44 may be adjusted depending on the state of the engine 1 and the vehicle 10. Once the process in step S108 is completed, the process proceeds to step S107.

[0036] As described above, according to this embodiment, when the engine start request is OFF and the exhaust temperature TC is below a predetermined temperature TCT, the motor 2 motors the engine 1. At this time, by making the opening of the exhaust throttle valve 44 smaller than fully open, the exhaust pressure PC upstream of the exhaust throttle valve 44 can be increased. As the exhaust pressure PC increases, the exhaust temperature TC increases, and the temperature of the catalyst 41 rises. In this way, even when the engine 1 is stopped, the temperature of the catalyst 41 can be maintained at an appropriate temperature. Therefore, it is possible to purify the exhaust immediately after the engine 1 is started. Furthermore, even if the engine start request is ON and motoring is interrupted, the engine 1 is started when the temperature of the catalyst 41 has risen to a certain extent, so the amount of harmful substances released into the atmosphere after the engine 1 is started can be reduced, and the time it takes for the catalyst 41 to rise to its active temperature can be reduced.

[0037] <Second Embodiment> Figure 3 is a diagram showing the schematic configuration of a vehicle 10 according to the second embodiment. The main differences from Figure 1 will be explained. The engine 1 is equipped with an EGR device 50 that recirculates a portion of the exhaust gas flowing through the exhaust passage 4 to the intake passage 3. This EGR device 50 has an EGR passage 51 It is configured to include an EGR valve 52.

[0038] The EGR passage 51 connects the exhaust passage 4 upstream of the catalyst casing 40 (i.e., the exhaust passage 4 upstream of the exhaust throttle valve 44) and the intake passage 3 downstream of the intake throttle valve 32. The gas in the exhaust passage is recirculated as EGR gas through this EGR passage 51. The EGR valve 52 adjusts the amount of EGR gas flowing through the EGR passage 51 by adjusting the passage cross-sectional area of ​​the EGR passage 51. The EGR valve 52 is connected to the ECU 100 via electrical wiring, and the control unit 110 of the ECU 100 controls the EGR valve 52.

[0039] A wall temperature sensor 33 is positioned in the intake passage 3 downstream of the point where the EGR passage 51 is connected to the intake passage 3 to detect the temperature of the wall surface of the intake passage 3. The wall temperature sensor 33 may be a sensor that detects the temperature of intake system components, or it may be a sensor that detects the temperature of components that are to be heated before the engine 1 is started. The wall temperature sensor 33 is connected to the ECU 100 via electrical wiring, and the output signal of the wall temperature sensor 33 is input to the ECU 100.

[0040] The control unit 110 supplies the exhaust gas, which has become hotter due to the motoring of the engine 1, to the intake passage 3 via the EGR device 50, thereby increasing the temperature of the walls of the intake passage 3, the temperature of the components in the intake passage 3, and the internal temperature of the engine 1. This promotes the evaporation of fuel injected from, for example, the fuel injection valve 12 after the engine 1 is started. Furthermore, it enables the engine 1 to be warmed up even before it is started.

[0041] Figure 4 is a flowchart showing the control flow in the ECU 100 according to the second embodiment. The routine shown in Figure 4 is repeatedly executed in the ECU 100 at predetermined time intervals. In step S201, the control unit 110 determines whether or not the engine start request is ON. The engine start request is the same as in the first embodiment. If the control unit 110 determines in step S201 that it is ON, the process proceeds to step S202.

[0042] In step S202, the control unit 110 fully opens the exhaust throttle valve 44 and fully closes the EGR valve 52. As a result, the exhaust gas from the engine 1 is released into the atmosphere after passing through the catalyst 41. The opening degree of the exhaust throttle valve 44 or the EGR valve 52 may be adjusted depending on the state of the engine 1 and the vehicle 10. For example, the exhaust throttle valve 44 may be controlled to the closed side in order to increase the load on the engine 1 while the engine 1 is running. Alternatively, the EGR valve 52 may be controlled to the open side in order to supply EGR gas to the intake passage 3 while the engine 1 is running. Once the process in step S202 is completed, the process proceeds to step S203.

[0043] In step S203, the control unit 110 turns off the motoring request. As a result, the control unit 110 terminates the motoring. Once the processing in step S203 is complete, this routine terminates.

[0044] Furthermore, if the control unit 110 determines that the condition is not met in step S201, the process proceeds to step S204. In step S204, the control unit 110 determines whether the wall temperature TW is equal to or greater than a predetermined wall temperature TWT. The control unit 110 obtains the wall temperature TW from the wall temperature sensor 33. As another example, the control unit 110 may estimate the wall temperature TW from the EGR gas temperature and the rotational speed of the engine 1 accumulated from the time control to open the EGR valve 52 is started. The predetermined wall temperature TWT is determined according to, for example, the temperature at which fuel evaporation is promoted, the temperature at which the increase in fuel injection amount becomes within an acceptable range, the temperature at which the emission of air pollutants becomes within an acceptable range, etc. The predetermined wall temperature TWT may be obtained by experiment or simulation and stored in the storage unit 120. If the wall temperature TW is equal to or greater than the predetermined wall temperature TWT, Motorizing Jin 1 is not necessary. Here, since excessive motoring would reduce the battery charge level, which is undesirable, one of the conditions for motoring is that the wall surface temperature TW is less than a predetermined wall surface temperature TWT. If the control unit 110 makes a positive determination in step S204, the process proceeds to step S202; if it makes a negative determination, the process proceeds to step S205.

[0045] In step S205, the control unit 110 determines whether the exhaust pressure PC is higher than a predetermined pressure PCMX. The control unit 110 obtains the exhaust pressure PC from the exhaust pressure sensor 43. The predetermined pressure PCMX may be the same value as in the first embodiment. Alternatively, the predetermined pressure PCMX may be a pressure threshold that enables effective supply of EGR gas to the intake passage 3. The predetermined pressure PCMX may be determined by experiment or simulation and stored in the storage unit 120. If the control unit 110 determines in step S205 that it is positive, the process proceeds to step S206.

[0046] In step S206, the control unit 110 increases the opening of the EGR valve 52 beyond its current opening. This reduces the exhaust pressure upstream of the exhaust throttle valve 44. At this time, the opening of the EGR valve 52 may be adjusted according to the state of the engine 1 and the vehicle 10. Alternatively, the control unit 110 may use feedback control to adjust the opening of the EGR valve 52 based on the value detected by the exhaust pressure sensor 43 so that the exhaust pressure PC is less than or equal to a predetermined pressure PCMX. Once the processing in step S206 is completed, the process proceeds to step S207.

[0047] In step S207, the control unit 110 determines whether the exhaust pressure PC is higher than a predetermined pressure PCMX. The control unit 110 makes this determination in the same manner as in step S205. However, it is possible that even when the EGR valve 52 is fully open, the exhaust pressure PC may not fall below the predetermined pressure PCMX. In such cases, the control unit 110 opens the exhaust throttle valve 44, as in the first embodiment. If the control unit 110 makes a positive determination in step S207, the process proceeds to step S208; if it makes a negative determination, the process proceeds to step S209.

[0048] In step S208, the control unit 110 increases the opening of the exhaust throttle valve 44 beyond its current opening. This reduces the exhaust pressure upstream of the exhaust throttle valve 44. In other words, if the exhaust pressure PC does not decrease sufficiently even when the opening of the EGR valve 52 is adjusted to the open side, the control unit 110 further adjusts the exhaust throttle valve 44 to the open side to reduce the exhaust pressure PC. The opening of the exhaust throttle valve 44 may be adjusted according to the state of the engine 1 and the vehicle 10. As another example, the control unit 110 may also use feedback control to adjust the opening of the exhaust throttle valve 44 based on the detected value of the exhaust pressure sensor 43 so that the exhaust pressure PC is below a predetermined pressure PCMX. Once the processing in step S208 is completed, the process proceeds to step S209.

[0049] In step S209, the control unit 110 turns on the motoring request. This initiates motoring of engine 1. Once the processing in step S209 is complete, this routine terminates.

[0050] On the other hand, if the control unit 110 determines that the condition is not met in step S205, the process proceeds to step S210. In step S210, the control unit 110 determines whether the exhaust temperature TC is equal to or greater than the second predetermined temperature TT. The control unit 110 obtains the exhaust temperature TC from the exhaust temperature sensor 42. As another example, the control unit 110 may estimate the exhaust temperature TC from the intake air temperature and exhaust pressure. The second predetermined temperature TT may be an exhaust temperature that can effectively raise the temperature of the walls of the intake passage 3, etc. If the exhaust temperature TC is equal to or greater than the second predetermined temperature TT, high-temperature EGR gas can be supplied to the intake passage 3 via the EGR passage 51. This allows the intake passage wall temperature TW to be increased. On the other hand, if the exhaust temperature TC is less than the second predetermined temperature TT, the control unit 110 fully closes the exhaust throttle valve 44, further increasing the exhaust temperature TC. If the control unit 110 makes an affirmative determination in step S210, the process proceeds to step S206; if it makes a negative determination, the process proceeds to step S211.

[0051] In step S211, the control unit 110 completely closes the exhaust throttle valve 44. This causes the exhaust pressure PC upstream of the exhaust throttle valve 44 to rise rapidly. As a result, the exhaust temperature TC also rises rapidly. The opening degree of the exhaust throttle valve 44 may be adjusted depending on the state of the engine 1 and the vehicle 10. Once the process in step S211 is completed, the process proceeds to step S209.

[0052] As described above, according to this embodiment, when the engine start request is OFF and the wall temperature TW is less than a predetermined wall temperature TWT, the motor 2 motors the engine 1. At this time, by making the opening of the exhaust throttle valve 44 smaller than fully open, the exhaust pressure PC upstream of the exhaust throttle valve 44 can be increased. As the exhaust pressure PC increases, the exhaust temperature TC increases, and therefore the temperature of the EGR gas also increases. Then, by opening the EGR valve 52, high-temperature EGR gas can be supplied to the intake passage 3, so the wall temperature TW of the intake passage 3 can be rapidly increased. In this way, even when the engine 1 is stopped, the wall temperature TW of the intake passage 3 can be maintained at an appropriate temperature. Also, even when the engine 1 is stopped, the internal temperature of the engine 1 can be raised to warm up the engine 1. Therefore, it is possible to promote fuel evaporation from immediately after starting the engine 1, and the amount of fuel injection can be reduced. Therefore, fuel efficiency can be improved. In addition, the concentration of harmful substances such as HC contained in the exhaust can be reduced.

[0053] Furthermore, the control unit 110 can execute the control according to the first embodiment and the control according to the second embodiment in parallel. If a conflicting process occurs between the control according to the first embodiment and the control according to the second embodiment, the control according to either the first embodiment or the control according to the second embodiment may be given priority. For example, in order to prioritize raising the temperature of the catalyst 41, the control according to the first embodiment may be executed preferentially. [Explanation of symbols]

[0054] 1 Engine 2 motors 3. Intake passage 4 Exhaust passage 10 vehicles 12 Fuel Injector 41 Catalyst 42 Exhaust temperature sensor 43 Exhaust pressure sensor 44 Exhaust throttle valve 100 ECU 110 Control Unit 120 Storage section

Claims

1. An engine having an exhaust catalytic converter and an exhaust throttle valve located downstream of the exhaust catalytic converter in the exhaust passage, The aforementioned engine is equipped with a motor capable of motorizing it, A vehicle control device for controlling a hybrid vehicle equipped with the following: The control unit includes a mechanism that, when there is no request to start the engine, performs motoring by completely closing the exhaust throttle valve, thereby raising the temperature of the exhaust purification catalyst, depending on whether the temperature in the exhaust passage is below a predetermined temperature. Vehicle control system.

2. When the control unit is performing a control to raise the temperature of the exhaust gas purification catalyst, it controls the opening degree of the exhaust throttle valve so that the pressure upstream of the exhaust throttle valve is below a predetermined pressure. A vehicle control device according to claim 1.

3. The control unit, in response to a request to start the engine, performs the actions of opening the exhaust throttle valve and terminating the motoring. A vehicle control device according to claim 1 or 2.

4. The engine further comprises an EGR passage connecting the exhaust passage and the intake passage upstream of the exhaust throttle valve, and an EGR valve for adjusting the cross-sectional area of ​​the EGR passage. The control unit, When there is no request to start the engine, the exhaust throttle valve is fully closed and the motoring is performed in accordance with the fact that the wall temperature of the intake passage is lower than a predetermined wall temperature. When the pressure in the exhaust passage upstream of the exhaust throttle valve becomes higher than a predetermined pressure, or when the temperature in the exhaust passage upstream of the exhaust throttle valve becomes higher than a second predetermined temperature, the EGR valve is controlled to open. A vehicle control device according to claim 1.

5. Even after the control unit has controlled the EGR valve to the open position, if the pressure in the exhaust passage upstream of the exhaust throttle valve is higher than the predetermined pressure, the control unit will control the exhaust throttle valve to the open position. The vehicle control device according to claim 4.

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