Control device for a vehicle

Abstract

The present application aims to promote warm-up of an exhaust purification catalyst. A control device of a vehicle controls a hybrid vehicle that is provided with an engine having an exhaust purification catalyst and an exhaust throttle valve disposed further downstream than the exhaust purification catalyst on an exhaust passage, and an electric motor capable of motor-driving the engine, the control device being provided with a control section that, when there is no request to start the engine, performs control to raise the temperature of the exhaust purification catalyst by setting the exhaust throttle valve to be fully closed and motor-driving the engine, in accordance with the temperature within the exhaust passage being less than a prescribed temperature.

Description

Technical Field

[0001] This invention relates to a vehicle control device. Background Technology

[0002] It is known that when the engine is predicted to start and the engine coolant temperature is below a threshold, the engine and electric motor are controlled to start the engine after warming up the engine based on motor driving (e.g., see Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2022-107218

[0004] Patent Document 2: Japanese Patent Application Publication No. 2008-302774

[0005] Patent Document 3: Japanese Patent Application Publication No. 2008-008206 Summary of the Invention

[0006] The purpose of this invention is to promote the warm-up of exhaust gas purification catalysts.

[0007] One aspect of the present invention is a vehicle control device that controls a hybrid vehicle, the hybrid vehicle comprising: an engine having an exhaust purification catalyst and an exhaust throttle valve disposed downstream of the exhaust purification catalyst in an exhaust passage; and an electric motor capable of driving the engine. The vehicle control device includes a control unit that, when there is no request to start the engine, sets the exhaust throttle valve to be completely closed and drives the electric motor based on the temperature in the exhaust passage being lower than a predetermined temperature, thereby performing control to increase the temperature of the exhaust purification catalyst.

[0008] Invention Effects

[0009] According to the present invention, it is possible to promote the warm-up of the exhaust gas purification catalyst. Attached Figure Description

[0010] Figure 1 This is a diagram showing the schematic structure of the vehicle according to the first embodiment.

[0011] Figure 2 This is a flowchart illustrating the control flow in the ECU according to the first embodiment.

[0012] Figure 3 This is a diagram showing the general structure of the vehicle according to the second embodiment.

[0013] Figure 4 This is a flowchart illustrating the control flow in the ECU according to the second embodiment. Detailed Implementation

[0014] Exhaust gas purification systems using precious metal catalysts require engine warm-up to a specified temperature, typically achieved through the heat of the incoming exhaust gas. For such systems, numerous techniques have been developed to accelerate warm-up by increasing exhaust temperature. For example, it is known to completely close the exhaust throttle valve, located downstream of the catalyst, and increase exhaust temperature through increased engine load caused by increased back pressure. Furthermore, it is known to raise exhaust temperature by controlling the low-pressure EGR valve, located downstream of the throttle valve, to open, thereby recirculating high-temperature EGR gas. On the other hand, before the exhaust gas purification system has fully warmed up, unpurified exhaust gas passes through the catalyst; therefore, it is also important to suppress the concentration and flow rate of harmful substances flowing into the catalyst before warm-up is complete.

[0015] In conventional combustion processes, heat is generated through combustion, resulting in exhaust gases containing harmful substances such as NOx and HC. To reduce the concentration of these harmful substances, techniques are known to generate heat using methods other than combustion, such as dedicated electric heating devices. However, dedicated electric heating devices are expensive and have complex system structures. Furthermore, as another example, techniques are known to compress air in the cylinder using a motor and control valve timing to effectively extract its heat. However, in this technique, the compressed air in the cylinder is discharged after an expansion stroke and expands further as it passes through the exhaust valve, resulting in a decrease in gas temperature. Therefore, the vehicle control device of the present invention, in order to suppress the release of harmful substances into the atmosphere, compresses air in the exhaust passage using a motor while the engine is stopped, thereby generating heat and supplying heat to the exhaust purification device without the accompanying temperature drop due to expansion.

[0016] Specifically, as one aspect of the present invention, a vehicle control device controls a hybrid vehicle, which includes: an engine having an exhaust purification catalyst and an exhaust throttle valve disposed downstream of the exhaust purification catalyst in the exhaust passage; and an electric motor capable of driving the engine. Hybrid vehicles include plug-in hybrid electric vehicles (PHEVs) and hybrid electric vehicles (HEVs). The exhaust purification catalyst is a catalyst requiring warm-up and has the function of sufficiently purifying harmful components in the exhaust gas above its activation temperature. The exhaust throttle valve adjusts the exhaust flow rate. The electric motor can drive the engine by rotating the engine's output shaft, for example, when no fuel is supplied to the engine. When the motor is driving the engine, air is discharged from the engine into the exhaust passage.

[0017] The vehicle's control unit includes a control unit that, when there is no request to start the engine, sets the exhaust throttle valve to full closure and operates the electric motor to drive the engine if the temperature in the exhaust passage is below a predetermined temperature. This controls the increase in temperature of the exhaust purification catalyst. "When there is no request to start the engine" can mean when starting the engine is not required. If starting the engine is required, the control unit can determine that there is a request to start the engine. When there is no request to start the engine, no fuel is supplied to the engine. Furthermore, when there is no request to start the engine, the engine can be operated by electric motor. In this case, by setting the exhaust throttle valve to full closure and operating the electric motor, the pressure in the exhaust passage upstream of the exhaust throttle valve increases. This causes the temperature in the exhaust passage upstream of the exhaust throttle valve to rise. The temperature in the exhaust passage can be either the exhaust temperature or the temperature of the exhaust purification catalyst. Since the temperature in the exhaust passage is below a predetermined temperature, by raising the temperature in the exhaust passage, the temperature in the exhaust passage can be increased to above the predetermined temperature. The predetermined temperature is, for example, the temperature at which the exhaust purification catalyst is activated. That is, by setting the exhaust throttle valve to be completely closed while driving the motor, the exhaust purification catalyst can be warmed up before the engine starts.

[0018] Additionally, "when there is no request to start the engine" can include situations where starting the engine is not currently required, but is predicted to be necessary. That is, it could also be a situation where starting the engine is imminent. For example, when the battery's remaining charge is close to the threshold for starting the engine, it can be determined that the engine will start soon. This helps to prevent unnecessary warm-up of the exhaust gas purification catalyst.

[0019] Furthermore, when controlling the temperature of the exhaust purification catalyst, the control unit can control the opening of the exhaust throttle valve to bring the pressure upstream of the exhaust throttle valve below a specified pressure. The specified pressure is the upper limit of the pressure at which no problems occur in the exhaust passage. These problems include pressure-induced component damage or exhaust leakage. In other words, when the pressure in the exhaust passage upstream of the exhaust throttle valve is high, by controlling the exhaust throttle valve to the open side, the pressure in the exhaust passage can be reduced, thus suppressing pressure-related problems in the exhaust passage.

[0020] Furthermore, the control unit can perform operations such as opening the exhaust throttle valve and stopping the motor drive according to a request to start the engine. In this way, the engine can be started immediately upon request. Additionally, even if the exhaust purification catalyst temperature is not sufficiently raised, starting the engine when the exhaust purification catalyst temperature has reached a certain level allows the exhaust purification catalyst to be activated earlier.

[0021] Furthermore, the engine also includes: an EGR passage connecting the exhaust passage upstream of the exhaust throttle valve and the intake passage; and an EGR valve that adjusts the cross-sectional area of ​​the EGR passage. When there is no request to start the engine, the control unit can set the exhaust throttle valve to be completely closed and drive the motor if the wall temperature of the intake passage is lower than a specified wall temperature. If the pressure in the exhaust passage upstream of the exhaust throttle valve is higher than a specified pressure or the temperature in the exhaust passage upstream of the exhaust throttle valve is higher than a second specified temperature, the EGR valve can be controlled to be on the open side.

[0022] The specified pressure is the upper limit of the pressure at which no problems will occur in the exhaust passage. These problems include component damage or exhaust leakage caused by pressure. That is, when the pressure in the exhaust passage upstream of the exhaust throttle valve is high, by keeping the EGR valve open, the pressure in the exhaust passage can be reduced, thus suppressing pressure-related problems in the exhaust passage. The intake passage wall temperature can be the temperature of the component being heated or the temperature of a specific engine component. Furthermore, the second specified temperature is the temperature at which the temperature of the components in the intake system or the engine interior rises to the warm-up completion temperature. When the temperature in the exhaust passage upstream of the exhaust throttle valve is high, by keeping the EGR valve open, high-temperature gas can be supplied to the intake passage. This allows the temperature of the components in the intake passage or the engine interior to be increased before engine start-up.

[0023] Furthermore, the control unit can, after controlling the EGR valve to the open side, control the exhaust throttle valve to the open side if the pressure in the exhaust passage upstream of the exhaust throttle valve is still higher than the predetermined pressure. Even if the EGR valve is controlled to the open side, if the pressure in the exhaust passage does not sufficiently decrease, the control unit reduces the pressure in the exhaust passage by controlling the exhaust throttle valve to the open side. This suppresses pressure-related problems in the exhaust passage.

[0024] In addition, the vehicle control device involved in this invention can be the following device:

[0025] The vehicle control device controls the hybrid vehicle, the hybrid vehicle comprising:

[0026] An engine having an exhaust gas purification catalyst and an exhaust gas throttle valve disposed downstream of the exhaust gas purification catalyst in an exhaust passage, and having an EGR passage connecting the exhaust passage, which is located upstream of the exhaust gas throttle valve, to an intake passage, and an EGR valve for adjusting the cross-sectional area of ​​the EGR passage; and

[0027] An electric motor, which can drive the engine.

[0028] The vehicle's control device includes a control unit, which performs the following controls:

[0029] When there is no request to start the engine, and the intake passage wall temperature is lower than a specified wall temperature, the exhaust throttle valve is set to be completely closed to drive the motor; and

[0030] When the pressure in the exhaust passage upstream of the exhaust throttle valve is higher than a specified pressure, or when the temperature in the exhaust passage upstream of the exhaust throttle valve is higher than a second specified temperature, the EGR valve is controlled to be on the open side.

[0031] Furthermore, the control unit can control the exhaust throttle valve to the open side after controlling the EGR valve to the open side, provided that the pressure in the exhaust passage upstream of the exhaust throttle valve is still higher than the specified pressure.

[0032] Furthermore, the control unit can execute steps such as opening the exhaust throttle valve, closing the EGR valve, and ending the motor drive according to a request to start the engine.

[0033] Hereinafter, with reference to the accompanying drawings, illustrative details will be provided regarding embodiments of the present invention. However, unless otherwise specified, the dimensions, materials, shapes, and relative arrangements of the constituent components described in this embodiment are not intended to limit the scope of the invention to these.

[0034] <First Embodiment>

[0035] Figure 1 This is a diagram showing the schematic structure of the vehicle 10 according to the first embodiment. The vehicle 10 is a hybrid vehicle such as a plug-in hybrid electric vehicle (PHEV) or a hybrid electric vehicle (HEV) that has an engine 1 and an electric motor 2. Figure 1 The engine 1 shown is, for example, an engine with four cylinders 11. Alternatively, engine 1 can be, for example, either a gasoline engine or a diesel engine. Engine 1 is an example of an internal combustion engine. The electric motor 2 is capable of rotating the output shaft (i.e., crankshaft) of engine 1 by supplying electricity.

[0036] Furthermore, the intake passage 3 and exhaust passage 4 are connected to the engine 1. An air flow meter 31 is installed in the intake passage 3, and this air flow meter 31 outputs a signal corresponding to the flow rate of the air flowing within the intake passage 3. The air flow meter 31 measures the amount of air intake by the engine 1. Furthermore, an intake throttle valve 32, adjusting the flow rate of the intake air flowing within the intake passage 3, is installed downstream of the air flow meter 3. This intake throttle valve 32 is opened and closed by an electric actuator, adjusting the cross-sectional area of ​​the intake passage 3. In the intake passage 3, which communicates with each cylinder 11 of the engine 1, a fuel injection valve 12 is installed for each cylinder 11.

[0037] Furthermore, a catalyst housing 40 is provided in the exhaust passage 4. A catalyst 41 is disposed inside the catalyst housing 40. The catalyst 41 can be, for example, DOC (oxidation catalyst), TWC (three-way catalyst), SCR (selective reduction NOx catalyst), SCRF (strain-cooled filter with SCR catalyst), or NSR (non-reducing NOx catalyst). The catalyst 41 exerts sufficient exhaust purification capability above its active temperature. However, the catalyst or filter disposed inside the catalyst housing 40 is not limited to these. An exhaust temperature sensor 42 for detecting the exhaust temperature and an exhaust pressure sensor 43 for detecting the exhaust pressure are disposed in the catalyst housing 40. An exhaust throttle valve 44, which adjusts the flow rate of the exhaust gas flowing within the exhaust passage 4, is provided downstream of the catalyst housing 40. This exhaust throttle valve 44 is opened and closed by an electric actuator to adjust the cross-sectional area of ​​the exhaust passage 4.

[0038] An ECU 100, serving as an electronic control unit, is connected to the engine 1. The ECU 100 includes a control unit 110 and a storage unit 120. The control unit 110 can be implemented using a hardware processor such as a CPU. Furthermore, the control unit 110 can be configured to include RAM, ROM, cache memory, etc. The storage unit 120 is a mechanism for storing information and is composed of storage media such as RAM or flash memory. The storage unit 120 stores the program executed by the control unit 110, the data used by that program, etc. The control unit 110 of the ECU 100 controls the engine 1 according to the operating conditions of the engine 1 or the driver's request.

[0039] Furthermore, the aforementioned sensors are connected to the ECU 100 via electrical wiring, and the output signals of these sensors are input to the ECU 100. Additionally, the ECU 100 is connected to the electric motor 2, fuel injection valve 12, intake throttle valve 32, and exhaust throttle valve 44 via electrical wiring, and the control unit 110 of the ECU 100 controls the electric motor 2, fuel injection valve 12, intake throttle valve 32, and exhaust throttle valve 44.

[0040] Furthermore, when there is no request to operate the engine 1 and the catalyst 41 is not activated, the control unit 10 rotates the crankshaft of the engine 1 via the electric 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 exhausts air from the engine 1 and compresses the air in the exhaust passage 4, which is located upstream of the exhaust throttle valve 44. Moreover, due to the compression of the air, the temperature of the air rises, thus the control unit 110 is able to raise the temperature of the catalyst 41.

[0041] Figure 2 This is a flowchart illustrating the control flow in the ECU100 according to the first embodiment. Figure 2 The routine shown is repeatedly executed in the ECU 100 at predetermined intervals. In step S101, the control unit 110 determines whether the engine start request is ON. The engine start request is ON when it is necessary to start the engine 1, and OFF when it is not necessary to start the engine 1. For example, if the remaining charge of the battery supplying power to the electric motor 2 is less than a threshold, the engine start request is ON in order to charge the battery. Also, for example, if the speed of the vehicle 10 is higher than the starting speed of the engine 1, the engine start request is ON in order to increase the driving force of the vehicle 10. Here, when the engine 1 is running, the control unit 110 cannot drive the motor of the engine 1. That is, the engine start request being OFF becomes one of the conditions for driving the motor. If the control unit 110 makes an affirmative determination in step S101, the process proceeds to step S102.

[0042] In step S102, the control unit 110 fully opens the exhaust throttle valve 44. The control unit 110 sets the exhaust throttle valve 44 to be fully open to release exhaust gas from the engine 1 during operation into the atmosphere. Alternatively, the opening degree of the exhaust throttle valve 44 can be adjusted according to the state of the engine 1 or the vehicle 10. For example, to increase the load on the engine 1 during operation, the exhaust throttle valve 44 can be controlled to be closed. If step S102 is completed, the process proceeds to step S103.

[0043] In step S103, the control unit 110 sets the motor drive request to OFF. The motor drive request is a request to drive the motor of engine 1. When the motor drive request is OFF, the control unit 110 does not drive the motor of engine 1. If the processing of step S103 is completed, this routine ends.

[0044] Furthermore, if the control unit 110 makes a negative determination in step S101, the process proceeds to step S104. In step S104, the control unit 110 determines whether the exhaust temperature TC is above or equal to a predetermined temperature TCT. The control unit 110 obtains the exhaust temperature TC from the exhaust temperature sensor 42. Alternatively, as another example, the control unit 110 can infer the exhaust temperature TC based on the intake air temperature and exhaust pressure. Furthermore, a sensor that detects the bed temperature of the catalyst 41 can be used instead of the exhaust temperature sensor 42. The predetermined temperature TCT can be set as the activation temperature of the catalyst 41, or it can be set as the exhaust temperature required to activate the catalyst 41. If the exhaust temperature TC is above or equal to the predetermined temperature TCT, then there is no need to drive the motor of the engine 1. Here, excessive motor driving would reduce the remaining charge of the battery, which is undesirable; therefore, an exhaust temperature TC lower than the predetermined temperature TCT is one of the conditions for driving the motor. In step S104, if the control unit 110 makes a positive determination, the process proceeds to step S102; if it makes a negative determination, the process proceeds to step S105.

[0045] In step S105, the control unit 110 determines whether the exhaust pressure PC is higher than the specified pressure PCMX. The control unit 110 obtains the exhaust pressure PC from the exhaust pressure sensor 43. Alternatively, the control unit 110 can calculate the exhaust pressure PC based on the intake air temperature and the accumulated engine speed of the engine 1 since the start of motor drive. Furthermore, the control unit 110 can infer the exhaust pressure PC based on the magnitude of the reaction force experienced by the electric motor 2 when it drives the engine 1. If the exhaust pressure PC becomes too high, it may cause damage to components such as the catalyst housing 40 disposed in the exhaust passage 4, or exhaust leakage from components disposed in the exhaust passage 4. Therefore, the control unit 110 controls the exhaust throttle valve 44 to make the exhaust pressure PC lower than the specified pressure PCMX. Therefore, the specified pressure PCMX is the upper limit of the exhaust pressure at which damage to components disposed in the exhaust passage 4 or exhaust leakage is suppressed. The specified pressure PCMX can be determined through experiments or simulations and stored in the storage unit 120. If the control unit 110 makes a positive determination in step S105, the process proceeds to step S106.

[0046] In step S106, the control unit 110 adjusts the opening of the exhaust throttle valve 44 to be greater than the current opening. This reduces the pressure of exhaust gases upstream of the exhaust throttle valve 44. Alternatively, the opening of the exhaust throttle valve 44 can be adjusted based on the state of the engine 1 or the vehicle 10. Furthermore, as another example, the control unit 110 can perform feedback control on the opening of the exhaust throttle valve 44 based on the detection value of the exhaust pressure sensor 43, so that the exhaust pressure PC is below a predetermined pressure PCMX. If step S106 is completed, the process proceeds to step S107.

[0047] In step S107, the control unit 110 sets the motor drive request to ON. This initiates motor drive of engine 1. If the processing in step S107 is complete, the routine ends.

[0048] On the other hand, if the control unit 110 makes a negative determination in step S105, the process proceeds to step S108. In step S108, the control unit 110 completely closes the exhaust throttle valve 44. As a result, the pressure of the exhaust gas upstream of the exhaust throttle valve 44 rises rapidly. Alternatively, the opening of the exhaust throttle valve 44 can be adjusted according to the state of the engine 1 or the vehicle 10. If the process in step S108 is completed, the process proceeds to step S107.

[0049] As explained above, according to this embodiment, when the engine start request is OFF and the exhaust temperature TC is less than the specified temperature TCT, the engine 1 is driven by the electric motor 2. At this time, by making the exhaust throttle valve 44 less than fully open, the exhaust pressure PC, which is upstream of the exhaust throttle valve 44, can rise. As the exhaust pressure PC rises and the exhaust temperature TC rises, the temperature of the catalyst 41 rises. Thus, even when the engine 1 is stopped, the temperature of the catalyst 41 can be maintained at an appropriate temperature. Therefore, exhaust purification can begin immediately after the engine 1 is started. Furthermore, even when the engine start request is ON and the electric motor drive is interrupted, the engine 1 is started while the temperature of the catalyst 41 is somewhat higher, thus reducing the amount of harmful substances released into the atmosphere after the engine 1 starts, or reducing the time it takes for the catalyst 41 to rise to its activation temperature.

[0050] <Second Implementation>

[0051] Figure 3 This is a diagram showing the schematic structure of the vehicle 10 according to the second embodiment. It mainly relates to... Figure 1 The different points will be explained. An EGR device 50 is provided in the engine 1 to recirculate a portion of the exhaust gas flowing in the exhaust passage 4 into the intake passage 3. The EGR device 50 is configured to include an EGR passage 51 and an EGR valve 52.

[0052] EGR passage 51 connects the exhaust passage 4, which is upstream of the catalyst housing 40 (i.e., upstream of the exhaust throttle valve 44), and the intake passage 3, which is downstream of the intake throttle valve 32. Through this EGR passage 51, the gas in the exhaust passage is recirculated as EGR gas. EGR valve 52 adjusts the amount of EGR gas flowing through the EGR passage 51 by adjusting the cross-sectional area of ​​the passage. EGR valve 52 is connected to ECU 100 via electrical wiring, and the control unit 110 of ECU 100 controls EGR valve 52.

[0053] A wall temperature sensor 33 is disposed on the intake passage 3, located downstream of the point where the EGR passage 51 connects to the intake passage 3, to detect the temperature of the wall surface of the intake passage 3. The wall temperature sensor 33 can be a sensor that detects the temperature of components of the intake system, or it can be a sensor that detects the temperature of components that are subject to temperature rise before the engine 1 is started. The wall temperature sensor 33 is connected to the ECU 100 via electrical wiring, and its output signal is input to the ECU 100.

[0054] The control unit 110 supplies exhaust gas, which has been heated by the electric motor driving the engine 1, to the intake passage 3 via the EGR device 50, causing the temperature of the walls of the intake passage 3, the temperature of the components in the intake passage 3, and the temperature inside the engine 1 to rise. This, for example, promotes the evaporation of fuel injected from the fuel injection valve 12 after the engine 1 is started. Furthermore, it allows for engine warm-up before starting the engine 1.

[0055] Figure 4 This is a flowchart illustrating the control flow in the ECU100 according to the second embodiment. Figure 4 The routine shown is repeatedly executed in the ECU 100 at predetermined intervals. In step S201, the control unit 110 determines whether the engine start request is ON. Regarding the engine start request, it is the same as in the first embodiment. If the control unit 110 makes an affirmative determination in step S201, the process proceeds to step S202.

[0056] In step S202, the control unit 110 sets the exhaust throttle valve 44 to fully open and the EGR valve 52 to fully close. As a result, the exhaust gas from the engine 1 is released into the atmosphere after passing through the catalyst 41. Alternatively, the opening degree of the exhaust throttle valve 44 or the EGR valve 52 can be adjusted according to the state of the engine 1 or the vehicle 10. For example, to increase the load on the engine 1 during operation, the exhaust throttle valve 44 can be controlled to the closed side. Furthermore, to supply EGR gas to the intake passage 3 during engine 1 operation, the EGR valve 52 can be controlled to the open side. If step S202 is completed, the process proceeds to step S203.

[0057] In step S203, the control unit 110 sets the motor drive request to OFF. Therefore, the control unit 110 terminates the motor drive. If the processing in step S203 is complete, this routine ends.

[0058] Furthermore, if the control unit 110 makes a negative determination in step S201, the process proceeds to step S204. In step S204, the control unit 110 determines whether the wall temperature TW is above or equal to a predetermined wall temperature TWT. The control unit 110 obtains the wall temperature TW from the wall temperature sensor 33. Alternatively, as another example, the control unit 110 can infer the wall temperature TW based on the EGR gas temperature and the accumulated engine speed of the engine 1 from the point when the control of the EGR valve 52 is opened. The predetermined wall temperature TWT is determined, for example, based on the temperature at which fuel evaporation is promoted, the temperature at which the increase in fuel injection quantity is within the allowable range, and the temperature at which the emission of atmospheric pollutants is within the allowable range. The predetermined wall temperature TWT can be obtained through experiments or simulations and stored in the storage unit 120. If the wall temperature TW is above or equal to the predetermined wall temperature TWT, then there is no need to drive the motor of the engine 1. Here, excessive motor driving will reduce the remaining battery charge, which is undesirable. Therefore, a wall temperature TW lower than a specified wall temperature TWT becomes one of the conditions for motor driving. In step S204, if the control unit 110 makes a positive determination, the process proceeds to step S202; if it makes a negative determination, the process proceeds to step S205.

[0059] 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 can be the same value as in the first embodiment. Alternatively, the predetermined pressure PCMX can be a threshold pressure at which EGR gas can be effectively supplied to the intake passage 3. The predetermined pressure PCMX can be determined experimentally or through simulation and stored in the storage unit 120. If the control unit 110 makes a positive determination in step S205, the process proceeds to step S206.

[0060] In step S206, the control unit 110 increases the opening degree of the EGR valve 52 to be greater than the current opening degree. This reduces the pressure of the exhaust gas upstream of the exhaust throttle valve 44. Furthermore, the opening degree of the EGR valve 52 can be adjusted according to the state of the engine 1 or the vehicle 10. Alternatively, the control unit 110 can perform feedback control on the opening degree of the EGR valve 52 based on the detection value of the exhaust pressure sensor 43, so that the exhaust pressure PC is below a predetermined pressure PCMX. If step S206 is completed, the process proceeds to step S207.

[0061] In step S207, the control unit 110 determines whether the exhaust pressure PC is higher than the specified pressure PCMX. The control unit 110 makes the determination in the same manner as in step S205. Here, it is also possible to consider a case where the exhaust pressure PC does not fall below the specified pressure PCMX even if the EGR valve 52 is fully open. In this case, the control unit 110 opens the exhaust throttle valve 44, similar to the first embodiment. In step S207, if the control unit 110 makes a positive determination, the process proceeds to step S208; if it makes a negative determination, the process proceeds to step S209.

[0062] In step S208, the control unit 110 adjusts the opening of the exhaust throttle valve 44 to be greater than the opening at the current time. This reduces the pressure of the exhaust gas upstream of the exhaust throttle valve 44. That is, even if the EGR valve 52 is adjusted to the open side, if the exhaust pressure PC is not sufficiently reduced, the control unit 110 further adjusts the exhaust throttle valve 44 to the open side to reduce the exhaust pressure PC. Alternatively, the opening of the exhaust throttle valve 44 can be adjusted according to the state of the engine 1 or the vehicle 10. Furthermore, as another example, the control unit 110 can perform feedback control on the opening of the exhaust throttle valve 44 based on the detection value of the exhaust pressure sensor 43 to make the exhaust pressure PC below a predetermined pressure PCMX. If step S208 is completed, the process proceeds to step S209.

[0063] In step S209, the control unit 110 sets the motor drive request to ON. This initiates motor drive of engine 1. If step S209 is completed, the routine ends.

[0064] On the other hand, if the control unit 110 makes a negative determination in step S205, the process proceeds to step S210. In step S210, the control unit 110 determines whether the exhaust temperature TC is above or equal to the second predetermined temperature TT. The control unit 110 obtains the exhaust temperature TC from the exhaust temperature sensor 42. Alternatively, as another example, the control unit 110 can infer the exhaust temperature TC based on the intake air temperature and exhaust pressure. The second predetermined temperature TT can be set as an exhaust temperature that can effectively increase the temperature of the wall surface of the intake passage 3, etc. If the exhaust temperature TC is above or equal to the second predetermined temperature TT, high-temperature EGR gas can be supplied to the intake passage 3 via the EGR passage 51. This can increase the wall temperature TW of the intake passage. On the other hand, if the exhaust temperature TC is less than the second predetermined temperature TT, the control unit 110 sets the exhaust throttle valve 44 to be completely closed, causing the exhaust temperature TC to rise further. In step S210, if the control unit 110 makes a positive determination, the process proceeds to step S206; if it makes a negative determination, the process proceeds to step S211.

[0065] In step S211, the control unit 110 completely closes the exhaust throttle valve 44. As a result, the exhaust pressure PC, which is upstream of the exhaust throttle valve 44, rises rapidly. Consequently, the exhaust temperature TC also rises rapidly. Alternatively, the opening of the exhaust throttle valve 44 can be adjusted according to the state of the engine 1 or the vehicle 10. If step S211 is completed, the process proceeds to step S209.

[0066] As explained above, according to this embodiment, when the engine start request is OFF and the wall temperature TW is less than the specified wall temperature TWT, the engine 1 is driven by the electric motor 2. At this time, by making the exhaust throttle valve 44 less than fully open, the exhaust pressure PC upstream of the exhaust throttle valve 44 can rise. Due to the increase in exhaust pressure PC, the exhaust temperature TC rises, and therefore the temperature of the EGR gas also rises. Moreover, by opening the EGR valve 52, high-temperature EGR gas can be supplied to the intake passage 3, thus causing the wall temperature TW of the intake passage 3 to rise rapidly. 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. Furthermore, even when the engine 1 is stopped, the internal temperature of the engine 1 can be increased to warm up the engine 1. Therefore, fuel evaporation can be promoted immediately after starting the engine 1, thereby reducing the amount of fuel injected. Therefore, fuel efficiency can be improved. Furthermore, the concentration of harmful substances such as HC contained in the exhaust can be reduced.

[0067] Furthermore, the controls involved in the first embodiment and the controls involved in the second embodiment can be executed in parallel by the control unit 110. In the event of a conflict between the controls involved in the first embodiment and the controls involved in the second embodiment, either control involved in the first embodiment or control involved in the second embodiment can be prioritized. For example, in order to prioritize the temperature rise of the catalyst 41, the controls involved in the first embodiment can be prioritized.

[0068] Symbol Explanation

[0069] 1-Engine, 2-Electric motor, 3-Intake passage, 4-Exhaust passage, 10-Vehicle, 12-Fuel injection valve, 41-Catalyst, 42-Exhaust temperature sensor, 43-Exhaust pressure sensor, 44-Exhaust throttle valve, 100-ECU, 110-Control unit, 120-Storage unit.

Claims

1. A vehicle control device for controlling a hybrid vehicle, the hybrid vehicle comprising: An engine having an exhaust purification catalyst and an exhaust throttle valve disposed downstream of the exhaust purification catalyst in the exhaust passage; and An electric motor, which can drive the engine. The control device for the vehicle is characterized by having: The control unit, when there is no request to start the engine, sets the exhaust throttle valve to be completely closed and drives the motor to drive it, thereby performing control to increase the temperature of the exhaust purification catalyst.

2. The vehicle control device according to claim 1, characterized in that, When the control unit performs the control to increase the temperature of the exhaust purification catalyst, it controls the opening of the exhaust throttle valve so that the pressure upstream of the exhaust throttle valve is below a specified pressure.

3. The vehicle control device according to claim 1 or 2, characterized in that, The control unit performs actions such as opening the exhaust throttle valve and stopping the motor drive according to the request to start the engine.

4. The vehicle control device according to claim 1, characterized in that, The engine also includes: an EGR passage connecting the exhaust passage and the intake passage, which are located upstream of the exhaust throttle valve; and an EGR valve that adjusts the cross-sectional area of ​​the EGR passage. The control unit performs the following controls: When there is no request to start the engine, and the intake passage wall temperature is lower than a specified wall temperature, the exhaust throttle valve is set to be completely closed to drive the motor; and When the pressure in the exhaust passage upstream of the exhaust throttle valve becomes higher than a specified pressure, or when the temperature in the exhaust passage upstream of the exhaust throttle valve becomes higher than a second specified temperature, the EGR valve is controlled to be on the open side.

5. The vehicle control device according to claim 4, characterized in that, After the control unit controls the EGR valve to the open side, if the pressure in the exhaust passage upstream of the exhaust throttle valve is still higher than the specified pressure, the control unit controls the exhaust throttle valve to the open side.

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