Vehicle control device

Abstract

To maintain a temperature of a catalyst of an exhaust gas purifier in a hybrid vehicle in consideration of the SOC of a battery.SOLUTION: A deceleration control unit 89 performs the following first or second control during deceleration of a vehicle 10. The first control is control to, when the SOC of a battery 26 is a first predetermined threshold value or more, increase engine resistance of an engine 1 so that the deceleration becomes larger than a required deceleration and allow a motor 21 to execute a motor assist operation in accordance with an amount of increase in the engine resistance. The second control is control to, when the SOC of the battery 26 is a second threshold value lower than the first threshold value, control a combustion state of the engine 1 to increase a temperature of an SCR catalyst 43 and allow the motor 21 to execute a regeneration operation.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a control device for a hybrid vehicle including an engine and a motor as driving sources for traveling.

Background Art

[0002] Hybrid vehicles equipped with an engine having a combustion chamber and an electric motor as driving sources for traveling have become widespread. In the exhaust system of the engine, a catalyst device for detoxifying exhaust gas is arranged. In the case of a diesel engine, an exhaust gas purification device having an SCR catalyst for purifying NOx may be used. In order to activate the catalyst, it is essential to maintain the catalyst at an appropriate operating temperature. Patent Document 1 discloses a control device that performs catalyst temperature increase control while causing motoring to rotate the engine in a fuel cut state when the catalyst temperature has not reached a predetermined temperature in a hybrid vehicle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a hybrid vehicle, during deceleration, regenerative braking based on the regenerative resistance of the motor may be used with the engine disengaged from the drive train. At this time, the electric power generated by the motor is stored in the battery. Therefore, for example, in a driving scenario where deceleration is performed on a long downhill slope, the SOC (State Of Charge) of the battery may reach the upper limit. In this case, the engine is connected to the drive train to be in a motoring state, and engine braking is utilized. On the other hand, since the engine will be at rest for a relatively long time, the catalyst temperature may drop below the set temperature. In this case, it is effective to cause combustion in the engine cylinder to maintain the catalyst temperature. However, if an attempt is made to substitute the regenerative brake for the loss of engine braking due to the combustion, the SOC will exceed the upper limit. For this reason, a problem may occur in that combustion for maintaining the catalyst temperature cannot be performed.

[0005] An object of the present invention is to provide a vehicle control device that can maintain the temperature of the catalyst of an exhaust gas purification device while taking into account the SOC of a battery in a hybrid vehicle.

Means for Solving the Problems

[0006] A vehicle control device according to an aspect of the present invention includes an exhaust system having a combustion chamber and a catalyst, an engine that generates a driving force for driving the driving wheels of the vehicle, a motor capable of driving the driving wheels, and a battery that supplies driving power to the motor in a motor assist operation in which the motor drives the driving wheels and is charged in a regenerative operation in which the motor generates electricity. The vehicle control device includes a control unit that controls the operation of the vehicle. The control unit, when the vehicle is decelerating, performs a first control in which when the SOC of the battery is equal to or higher than a first predetermined value, the engine resistance is increased so that the deceleration is greater than the required deceleration, and the motor assist operation is executed according to the increase in the engine resistance, or a second control in which when the SOC of the battery is a second predetermined value lower than the first predetermined value, the combustion state of the engine is controlled to increase the temperature of the catalyst, and the regenerative operation is executed.

[0007] According to this aspect, when the vehicle decelerates, first control or second control is performed according to the state of charge (SOC) of the battery. In the first control, while increasing the engine resistance to strengthen the engine brake, a motor assist operation is performed to consume the power of the battery. That is, the SOC is decreased. On the contrary, in the second control, the engine is combusted to increase the temperature of the catalyst and maintain the catalyst temperature. Also, a regeneration operation is performed by utilizing the margin of the SOC, that is, the difference between the first predetermined value and the second predetermined value, to generate a regenerative brake. Therefore, it is possible to achieve both suppression of overcharging of the battery and maintenance of the catalyst temperature.

[0008] In the above vehicle control device, it is desirable that the control unit performs the first control even when the temperature of the catalyst is lower than the set temperature, and switches to the second control when the SOC decreases to the second predetermined value by the execution of the first control.

[0009] According to this aspect, even when the temperature of the catalyst is lower than the set temperature, cooperative control is performed in which first the battery is discharged by the first control to give a margin to the SOC, and then the catalyst is heated by the subsequent second control. In the first control, the motor torque based on the motor assist operation can cancel out the strengthening of the engine brake. Also, in the second control following the first control, a deceleration corresponding to the amount of the engine brake disappearing due to the regenerative brake can be created. Therefore, it is possible to maintain the drivability without giving a sense of discomfort to the driver during deceleration.

[0010] In the above-described vehicle control device, the vehicle further includes a clutch that changes a torque transmission state between an output shaft of the engine and a drive shaft of the drive wheels. The control unit releases the clutch to disconnect the engine from the drive shaft, and when the SOC is equal to or higher than the first predetermined value and the temperature of the catalyst is higher than the set temperature in a state where deceleration is being performed by the regenerative resistance of the motor, the control unit performs a third control of engaging the clutch and rotating the engine in a fuel cut state to generate a first engine resistance. During the execution of the third control, when the temperature of the catalyst becomes lower than the set temperature, it is desirable to perform the first control with a second engine resistance that is greater than the first engine resistance.

[0011] According to this aspect, when the SOC becomes equal to or higher than the first predetermined value in a state where deceleration is being performed by the regenerative brake, the third control for generating an engine brake by motorring is performed. Thereby, an increase in the SOC is suppressed. Further, when the catalyst temperature becomes lower than the set temperature while the third control is being performed, the first control is performed by increasing the engine resistance, and the engine brake is strengthened. This strengthening of the engine brake is offset by the motor assist operation. Therefore, it is possible to form a state in which the second control for performing combustion that reduces the SOC and increases the catalyst temperature can be subsequently executed while maintaining drivability.

[0012] In the above-described vehicle control device, it is desirable that the control unit switches to the first control when the SOC becomes equal to or higher than the first predetermined value in a state where the deceleration of the vehicle continues after switching to the second control.

[0013] According to this aspect, during the deceleration operation of the vehicle, the first control and the second control are repeated according to the SOC of the battery. Therefore, for example, even when driving on a long downhill slope, it is possible to maintain the catalyst temperature without overcharging the battery.

[0014] In the above vehicle control device, in the second control, it is desirable that the control unit controls the combustion state so that the load on the engine becomes zero.

[0015] According to this aspect, in the second control, the engine performs combustion only for heating the catalyst without generating torque for driving. Therefore, the driver does not feel an acceleration feeling during the deceleration operation of the vehicle.

[0016] In the above vehicle control device, it is desirable that the control unit sets the regeneration resistance of the motor in the second control so as to compensate for the disappearance of the engine resistance due to the switching from the first control to the second control.

[0017] According to this aspect, the deceleration corresponding to the engine brake that disappears at the end of the first control can be compensated by the regenerative brake. Therefore, even when the switching from the first control to the second control occurs, the driver does not feel a sense of discomfort in the deceleration feeling.

[0018] In the above vehicle control device, as a control for increasing the engine resistance, the control unit may execute a control for reducing the in-cylinder pressure of the engine below the ambient environment to increase the piston resistance. According to this aspect, the engine resistance can be easily increased by operating the in-cylinder pressure.

[0019] In the above vehicle control device, the vehicle includes a transmission between the drive shafts of the drive wheels of the engine and the motor, and as a control for increasing the engine resistance, the control unit may perform a control for downshifting the gear stage of the transmission. According to this aspect, the engine resistance can be easily increased by downshifting.

[0020] In the above vehicle control device, it is desirable that the control unit causes fuel injection to be performed during the expansion stroke of the engine as a control for increasing the temperature of the catalyst.

[0021] According to this aspect, it is easy to perform combustion that does not substantially generate engine torque. Therefore, the catalyst temperature can be maintained without acceleration during deceleration.

[0022] In the vehicle control device described above, the vehicle includes a supercharger that supercharges the air supplied to the combustion chamber of the engine, and it is desirable that the control unit controls the supercharger to increase the supercharging pressure when performing control to raise the temperature of the catalyst.

[0023] When fuel injection is performed during the expansion stroke, there is a tendency for the injected fuel to easily adhere to the inner wall of the cylinder. By increasing the supercharging pressure, the flight distance of the fuel injected into the cylinder becomes shorter, and as a result, the adhesion of the fuel to the inner wall can be suppressed.

Effect of the Invention

[0024] According to the present invention, in a hybrid vehicle, it is possible to provide a vehicle control device that can maintain the temperature of the catalyst of the exhaust gas purification device while taking into account the SOC of the battery.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0026] Hereinafter, based on the drawings, a vehicle control device according to an embodiment of the present invention will be described in detail. The vehicle controlled by the control device of the present embodiment includes, as a traveling drive source for driving the drive wheels of the vehicle, an engine having a combustion chamber and an electric motor, and is a hybrid vehicle having a catalyst in the exhaust system of the engine.

[0027] [Overall Configuration of Hybrid Vehicle] FIG. 1 is a block diagram showing a schematic configuration of a hybrid vehicle 10 according to the present embodiment. The vehicle 10 includes an internal combustion engine type engine 1, a motor 21, an automatic transmission 22, a clutch CL1, a differential device 23, drive wheels 24, an inverter 25 and a battery 26, and a processor 80 as a vehicle control device in the present embodiment. Both the engine 1 and the motor 21 can apply a driving force for traveling to the drive wheels 24.

[0028] The engine 1 is an internal combustion engine that generates a driving force by burning fuel. The engine 1 of the present embodiment is a four-cycle diesel engine using light oil as fuel. The engine 1 may be a gasoline engine using fuel mainly composed of gasoline.

[0029] The motor 21 is, for example, a three-phase AC synchronous motor generator, and generates a driving force by receiving the supply of electric power stored in the battery 26. When the vehicle 10 decelerates, the motor 21 performs a regeneration operation of generating electricity by the rotational force transmitted from the drive wheels 24. In this case, a regeneration resistance corresponding to the electric power generated by the motor 21 acts on the drive wheels 24. The regeneration resistance becomes a regeneration braking force for decelerating the vehicle 10. The generated electric power of the motor 21 is charged into the battery 26 via the inverter 25.

[0030] The engine 1 and the motor 21 are connected in series via the clutch CL1. The motor 21 is connected to the drive shaft of the drive wheels 24 via the automatic transmission 22 and the differential device 23. With this configuration, both the engine 1 and the motor 21 can drive the drive wheels 24 of the vehicle 10. The clutch CL1 connects or disconnects the crankshaft, which is the output shaft of the engine body 2, and the rotating shaft of the motor 21.

[0031] The automatic transmission 22 has a function of shifting and outputting the rotations of the output shaft of the engine body 2 and the rotating shaft of the motor 21. The automatic transmission 22 includes an input shaft, a plurality of planetary gear mechanisms, a plurality of brake mechanisms, a plurality of clutch mechanisms, and an output shaft. The automatic transmission 22 shifts the speed of the rotating shaft by switching the transmission path of the rotational force input to the input shaft by the operation of each mechanism, and outputs it from the output shaft. The input shaft is connected to the rotating shaft of the motor 21. The output shaft is directly or indirectly connected to the differential device 23 via a drive shaft. Note that the plurality of clutch mechanisms of the transmission 6 can be generally regarded as one clutch CL2 in order for them to cooperate to realize a desired gear stage. Therefore, when the clutch CL2 is disengaged, the torque transmission between the input shaft and the output shaft is interrupted.

[0032] In a state where the clutch CL2 of the transmission 6 is engaged and the clutch CL1 is disengaged, only the driving force generated by the motor 21 is transmitted to the drive wheels 24 via the automatic transmission 22. On the other hand, in a state where both the clutches CL1 and CL2 are engaged, the driving forces of the engine 1 and the motor 21 are transmitted to the drive wheels 24. At this time, when the motor 21 does not generate a driving force, that is, when no power is supplied to the motor 21, only the driving force generated by the engine 1 is transmitted to the drive wheels 24.

[0033] With the above driving modes, the vehicle 10 can travel in any of the following modes: a motor driving mode in which it travels only by the driving force of the motor 21, a composite driving mode in which it travels by the driving forces of both the motor 21 and the engine 1, and an engine driving mode in which it travels only by the driving force of the engine 1. In the composite driving mode, the required torque of the vehicle 10 is shared by the engine torque generated by the engine 1 and the motor torque generated by the motor 21. For example, in the composite driving mode, although mainly aiming to travel with engine torque, when the required torque cannot be satisfied only by the engine torque, a motor assist operation is performed to supplement the shortage with motor torque. As will be described later, in the present embodiment, when the engine brake is strengthened more than the required deceleration, the term motor assist operation is also used for the operation of generating motor torque so as to cancel out the strengthening amount of the engine brake.

[0034] The battery 26 is a rechargeable secondary battery. As the battery 26, for example, a lithium-ion battery or a nickel-metal hydride battery is applicable. When the motor 21 generates a driving force including the motor assist operation, the battery 26 supplies driving power to the motor 21 via the inverter 25. Further, in the regeneration operation in which the motor 21 generates electric power, the battery 26 is charged by receiving the electric power generated via the inverter 25.

[0035] The inverter 25 performs conversion of three-phase AC power into DC power and vice versa. Specifically, when the motor 21 generates a driving force, the inverter 25 converts the DC power stored in the battery 26 into three-phase AC power and supplies it to the motor 21. On the other hand, when three-phase AC power is generated by the motor 21, the inverter 25 converts the three-phase AC power into DC power and supplies it to the battery 26.

[0036] The processor 80 comprehensively controls the operations of the vehicle 10 including the engine 1, the motor 21, the inverter 25, the automatic transmission 22, the clutch CL1, etc., so that the running of the vehicle 10 according to the driving conditions is realized. The processor 80 is configured based on a well-known microcomputer and includes a CPU (Central Processing Unit) that executes various programs and a memory such as a ROM and a RAM for storing programs and various data. The functional configuration of the processor 80 will be described later with reference to FIG. 3.

[0037] [Overall Configuration of Engine] FIG. 2 is a system diagram showing the overall configuration of the engine. The engine 1 illustrated in FIG. 2 is a four-cycle diesel engine. The engine 1 includes an engine body 2, an intake passage 30 through which intake air introduced into the engine body 2 flows, an exhaust passage 40 through which exhaust gas discharged from the engine body 2 flows, an EGR device 50 that recirculates a part of the exhaust gas flowing through the exhaust passage 40 to the intake passage 30, and an exhaust turbo device 60 that supercharges the intake air flowing through the intake passage 30. The operation of the engine 1 is controlled by the processor 80.

[0038] The engine body 2 has a plurality of cylinders 2a arranged in a direction orthogonal to the plane of FIG. 2. The engine body 2 includes a cylinder block 3, a cylinder head 4, and a plurality of pistons 5. The cylinders 2a are formed by the cylinder block 3 and the cylinder head 4. That is, a plurality of cylindrical spaces corresponding to the plurality of cylinders 2a are formed inside the cylinder block 3, and the cylinder head 4 is attached to the upper surface of the cylinder block 3 so as to close the cylindrical space from above. The pistons 5 are respectively accommodated in the cylinders 2a so as to be reciprocally slidable.

[0039] Above the piston 5 of each cylinder 2a, a combustion chamber C is formed respectively. Each combustion chamber C is a space partitioned by the lower surface of the cylinder head 4, a cylinder liner constituting the side circumferential surface of the cylinder 2a, and the crown surface of the piston 5. The combustion chamber C receives the supply of fuel injected from an injector 9 described later. The piston 5 reciprocates in the vertical direction receiving the combustion energy of the fuel supplied to the combustion chamber C.

[0040] Below the piston 5 and at the lower part of the cylinder block 3, a crankshaft 7 which is the output shaft of the engine body 2 is provided. The crankshaft 7 is connected to the piston 5 of each cylinder 2a via a connecting rod 8, and rotates around the central axis according to the reciprocating motion of the piston 5.

[0041] A crank angle sensor SN1 and a water temperature sensor SN2 are attached to the cylinder block 3. The crank angle sensor SN1 detects the crank angle which is the rotation angle of the crankshaft 7 and the engine speed which is the rotational speed of the crankshaft 7. Based on the detection result of the crank angle sensor SN1, it is possible to calculate the vehicle speed and acceleration of the vehicle 10. The water temperature sensor SN2 detects the temperature of the cooling water flowing inside the cylinder block 3 and the cylinder head 4, that is, the engine water temperature.

[0042] An injector 9 is attached to the cylinder head 4. The injector 9 supplies fuel to the combustion chamber C of each cylinder 2a. The injector 9 is attached to the cylinder head 4 such that its tip portion is exposed to the combustion chamber C. A plurality of injection holes serving as fuel outlets are formed in the tip portion of the injector 9. The fuel injected from each injection hole burns by auto-ignition in the combustion chamber C which has been heated and pressurized by the compression action of the piston 5.

[0043] The cylinder head 4 is formed with an intake port 11 and an exhaust port 12. The intake port 11 is a port that connects the combustion chamber C of each cylinder 2a and the intake passage 30. The exhaust port 12 is a port that connects the combustion chamber C of each cylinder 2a and the exhaust passage 40. An intake valve 13 is provided at the intake port 11 of each cylinder 2a. An exhaust valve 14 is provided at the exhaust port 12 of each cylinder 2a.

[0044] The cylinder head 4 is equipped with an intake valve operating mechanism 15 and an exhaust valve operating mechanism 16. The intake valve operating mechanism 15 drives the intake valve 13 of each cylinder 2a to open and close in conjunction with the rotation of the crankshaft 7. The exhaust valve operating mechanism 16 drives the exhaust valve 14 of each cylinder 2a to open and close in conjunction with the rotation of the crankshaft 7. The intake valve 13 periodically opens and closes the opening on the combustion chamber C side of the intake port 11 in response to the drive of the intake valve operating mechanism 15. The exhaust valve 14 periodically opens and closes the opening on the combustion chamber C side of the exhaust port 12 in response to the drive of the exhaust valve operating mechanism 16.

[0045] The intake passage 30 is a passage for introducing intake air into the combustion chamber C of each cylinder 2a. The intake passage 30 has an intake manifold 30a and a surge tank 30b in a downstream portion closer to the engine body 2. The surge tank 30b is a tank that provides an enlarged space for equalizing the intake air introduction amount to each cylinder 2a. The intake manifold 30a includes a plurality of branch pipes that connect the surge tank 30b and the intake port 11 of each cylinder 2a.

[0046] An air cleaner 31, an intercooler 32, and an intake shutter valve 33 are sequentially provided in a portion of the intake passage 30 upstream of the surge tank 30b. The air cleaner 31 is a filter that removes foreign substances in the intake air. The intercooler 32 is a heat exchanger that cools the intake air compressed by the exhaust turbo device 60. The intake shutter valve 33 is a butterfly valve provided in the intake passage 30 so as to be openable and closable to throttle the intake air flow rate.

[0047] In the intake passage 30, an air flow sensor SN3, an intake pressure sensor SN4, and an intake air temperature sensor SN5 are attached. The air flow sensor SN3 is a sensor that detects the flow rate of the intake air introduced into the engine body 2, and is disposed at a portion downstream of the air cleaner 31 in the intake passage 30. The intake pressure sensor SN4 is a sensor that detects the pressure of the intake air introduced into the engine body 2, and is disposed in the surge tank 30b. The intake air temperature sensor SN5 is a sensor that detects the temperature of the intake air, and is disposed downstream of the intercooler 32.

[0048] The exhaust passage 40 is a passage for discharging the exhaust gas discharged from the combustion chamber C of each cylinder 2a to the outside. The exhaust passage 40 has an exhaust manifold 40a at an upstream portion close to the engine body 2. The exhaust manifold 40a includes a plurality of branch pipes communicating with the exhaust ports 12 of each cylinder 2a, and an exhaust gas collecting portion where the branch pipes converge.

[0049] In a portion of the exhaust passage 40 downstream of the exhaust manifold 40a, a plurality of catalysts for purifying various harmful components contained in the exhaust gas are disposed. Specifically, an oxidation catalyst 41, a DPF (Diesel Particulate Filter) 42, an SCR (Selective Catalytic Reduction) catalyst 43, and a slip catalyst 44 are arranged in order from the upstream side of the exhaust gas flow. Between the DPF 42 and the SCR catalyst 43 in the exhaust passage 40, a urea injector 45 and a mixing plate 47 are disposed.

[0050] The oxidation catalyst 41 oxidizes and detoxifies CO and HC in the exhaust gas. The oxidation catalyst 41 has, for example, a porous carrier and a catalyst substance such as platinum or palladium supported on the carrier. The DPF 42 collects particulate matter such as soot contained in the exhaust gas. The DPF 42 contains a catalyst substance such as platinum for burning soot under high temperature conditions during filter regeneration.

[0051] The SCR catalyst 43 reduces and detoxifies NOx in the exhaust gas. The SCR catalyst 43 has, for example, a porous carrier and a catalyst substance such as vanadium, tungsten, or zeolite supported on the carrier. The SCR catalyst 43 supports ammonia generated from aqueous urea solution. The SCR catalyst 43 converts NOx in the exhaust gas into N2 and H2O by a chemical reaction using this ammonia as a reducing agent.

[0052] The slip catalyst 44 is an oxidation catalyst for oxidizing ammonia that has slipped from the SCR catalyst 43, that is, ammonia that has flowed out to the downstream side without being used for reducing NOx. As the slip catalyst 44, for example, one having the same structure as the oxidation catalyst 41 can be used.

[0053] The urea injector 45 supplies aqueous urea solution to the SCR catalyst 43. The urea injector 45 injects aqueous urea solution in which high-purity urea is dissolved into the inside of the exhaust passage 40. The urea injector 45 is supplied with aqueous urea solution from a tank 46 that stores the aqueous urea solution through a supply pipe 46a. When the urea injector 45 injects the aqueous urea solution, the urea contained in the aqueous urea solution is converted into ammonia by hydrolysis at high temperature and adsorbed by the SCR catalyst 43. The mixing plate 47 sends the aqueous urea solution injected from the urea injector 45 to the downstream SCR catalyst 43 while uniformly dispersing it. The mixing plate 47 is a plate-like member that partitions the exhaust passage 40 back and forth, and a plurality of openings are formed for stirring the flow of the exhaust gas.

[0054] In order to activate the SCR catalyst 43 and achieve a good NOx purification effect, it is necessary to maintain the SCR catalyst 43 within an appropriate temperature range. The temperature range is, for example, a high-temperature region exceeding 150°C. When the temperature of the SCR catalyst 43 drops below a predetermined high-temperature region, the NOx purification effect of the SCR catalyst 43 decreases. For example, when the engine 1 is started immediately after cold start or when fuel cut operation continues for a long time during driving on a long downhill slope, the purification ability of the SCR catalyst 43 decreases. Note that the three-way catalyst used when the engine 1 is a gasoline engine also has a reduced exhaust gas purification ability when the catalyst temperature drops.

[0055] In particular, in the hybrid vehicle 10, the engine 1 tends to stop for a long time, and the temperature of the SCR catalyst 43 is likely to drop. For example, when driving on a long downhill slope, there are scenarios where the clutch CL1 is disengaged to stop the engine 1 and the vehicle runs relying on the regenerative brake, or scenarios where the clutch CL1 is engaged to perform motoring driving. If these driving scenarios continue for a long time, the temperature of the SCR catalyst 43 will drop. In view of such problems, in the present embodiment, control is performed to maintain the temperature of the SCR catalyst 43 while taking into account that the SOC of the battery 26 does not exceed the upper limit. This will be described in detail later.

[0056] An exhaust O2 sensor SN6, a NOx concentration sensor SN7, and an exhaust temperature sensor SN8 are arranged in the exhaust passage 40. The exhaust O2 sensor SN6 is arranged upstream of the oxidation catalyst 41 in the exhaust passage 40 and measures the amount of oxygen in the exhaust gas. The NOx concentration sensor SN7 is arranged in the portion between the DPF 42 and the SCR catalyst 43 and detects the concentration of NOx contained in the exhaust gas. The exhaust temperature sensor SN8 is arranged in the portion downstream of the NOx concentration sensor SN7 and immediately upstream of the SCR catalyst 43 and detects the temperature of the exhaust gas. The detection value of the exhaust temperature sensor SN8 is used for estimating the temperature of the SCR catalyst 43.

[0057] The exhaust turbocharger 60 supercharges the air supplied to the combustion chamber C by utilizing the exhaust gas discharged from the combustion chamber C. The exhaust turbocharger 60 includes a compressor 61, a turbine 62, and a VGT actuator 63. The compressor 61 is disposed at a portion between the air cleaner 31 and the intercooler 32 in the intake passage 30. The turbine 62 is disposed at a portion upstream of the oxidation catalyst 41 in the exhaust passage 40. The exhaust gas discharged from the engine body 2 is introduced into the turbine 62, and the turbine 62 is rotationally driven by the exhaust gas. The compressor 61 rotates in conjunction with the turbine 62 to pump the intake air to the downstream side. That is, supercharging is performed to compress the intake air in the intake passage 30 and send it to the engine body 2.

[0058] The turbine 62 is of the VGT (Variable Geometry Turbocharger) specification with a variable vane mechanism for changing the exhaust gas flow rate (turbine capacity). The variable vane mechanism includes a plurality of nozzle vanes whose angles can be changed. By adjusting the angles of the nozzle vanes, the exhaust gas flow rate is adjusted. The VGT actuator 63 is an actuator for adjusting the angles of the nozzle vanes.

[0059] The EGR device 50 includes an EGR passage 51, an EGR cooler 52, and an EGR valve 53. The EGR passage 51 is a passage for recirculating the exhaust gas from the exhaust passage 40 to the intake passage 30. The EGR passage 51 connects a portion upstream of the turbine 62 in the exhaust passage 40 and a portion between the intake shutter valve 33 and the surge tank 30b in the intake passage 30. The EGR cooler 52 cools the EGR gas recirculated to the intake passage 30 through the EGR passage 51. The EGR valve 53 is a valve for adjusting the recirculation amount of the EGR gas.

[0060] [Vehicle control system] FIG. 3 is a functional block diagram showing the control system of the vehicle 10. In addition to the engine 1 and the motor 21, the vehicle 10 includes a processor 80 that comprehensively controls each part of the vehicle 10. Detection information from various sensors is input to the processor 80. For example, information detected by a crank angle sensor SN1, a water temperature sensor SN2, an air flow sensor SN3, an intake pressure sensor SN4, an intake air temperature sensor SN5, an exhaust O2 sensor SN6, a NOx concentration sensor SN7, and an exhaust temperature sensor SN8, that is, information such as crank angle, engine speed, engine water temperature, intake air flow rate, intake air pressure, intake air temperature, exhaust oxygen amount, NOxn concentration, and exhaust temperature, is sequentially input.

[0061] In addition to the above-mentioned sensor group, an outside air temperature sensor SN9 and an accelerator opening sensor SN10 are installed in the vehicle 10. The outside air temperature sensor SN9 measures the outside air temperature around the vehicle 10. The accelerator opening sensor SN10 detects the opening of the accelerator pedal operated by the driver of the vehicle, that is, the accelerator opening. The accelerator opening information is information for obtaining the required torque for the engine system including the engine 1 and the motor 21 in the vehicle 10. Detection information by the outside air temperature sensor SN9 and the accelerator opening sensor SN10 is also sequentially input to the processor 80.

[0062] The processor 80 controls each part of the vehicle 10 based on the input information from the above-mentioned sensors SN1 to SN10. The processor 80 is electrically connected to the injector 9, the intake shutter valve 33, the EGR valve 53, the urea injector 45, the VGT actuator 63, the automatic transmission 22, and the inverter 25 described above. The processor 80 outputs a control signal generated based on the input information from the sensors SN1 to SN10 to these devices.

[0063] When a predetermined program is executed, the processor 80 operates to functionally include an engine control unit 81, a motor control unit 82, a required torque calculation unit 83, an engine torque calculation unit 84, a motor torque calculation unit 85, a catalyst temperature estimation unit 86, an SOC calculation unit 87, a storage unit 88, and a deceleration control unit 89 (control unit).

[0064] The engine control unit 81 controls the operation of the engine 1. The engine control unit 81 determines the intake air amount, fuel injection amount, etc. so as to output the finally set engine torque to the engine 1 according to various situations, and controls the injector 9, the intake shutter valve 33, etc. The motor control unit 82 controls the inverter 25 so that the finally set motor torque is output by the motor 21.

[0065] The required torque calculation unit 83 calculates the required torque of the vehicle 10 according to the driver's accelerator operation, that is, based on the accelerator opening detected by the accelerator opening sensor SN10. In the hybrid vehicle 10 of the present embodiment, this required torque is shared by the engine torque generated by the engine 1 and the motor torque generated by the motor 21. The engine torque calculation unit 84 calculates the engine torque to be generated in the engine 1 according to the driving situation, required torque, etc. The motor torque calculation unit 85 calculates the motor torque to be generated in the motor 21 according to the driving situation, required torque, etc.

[0066] The catalyst temperature estimation unit 86 performs a calculation process for estimating the temperature of the SCR catalyst 43. An example of the calculation process of the catalyst temperature estimation unit 86 will be given. Based on the temperature of the exhaust gas immediately before the SCR catalyst 43 detected by the exhaust gas temperature sensor SN8 and the flow rate of the exhaust gas, the heat input amount to the SCR catalyst 43 is calculated. The flow rate of the exhaust gas can be estimated from the intake air flow detected by the air flow sensor SN3, the opening degree of the EGR valve 53, etc. Next, based on the vehicle speed derived from the detection value of the crank angle sensor SN1 and the outside air temperature detected by the outside air temperature sensor SN9, the heat dissipation amount from the SCR catalyst 43 is calculated. Then, based on the heat input amount, the heat dissipation amount, and the heat capacity of the SCR catalyst 43 stored in advance, the temperature Ts of the SCR catalyst 43 is calculated. Instead of the catalyst temperature estimation unit 86, a sensor for directly measuring the temperature of the SCR catalyst 43 may be provided.

[0067] The SOC calculation unit 87 performs calculations to estimate the current SOC of the battery 26. The SOC calculation unit 87 calculates the integrated charge amount by continuously integrating the charge and discharge current values detected by the current detector installed in the charge and discharge circuit of the battery 26. During this integration, the charging charge is added during charging, and the discharging charge is subtracted during discharging, thereby calculating the integrated charge amount. The SOC of the battery 26 is calculated from this integrated charge amount.

[0068] The storage unit 88 stores the setting values and data necessary for the processing of the processor 80. In the present embodiment, the storage unit 88 stores SOC-related setting information (such as the first predetermined value and the second predetermined value of SOC), such as the heat capacity of the SCR catalyst 43, the set temperature suitable for the operation of the SCR catalyst 43, and the upper limit SOC (for example, 80%) of the battery 26.

[0069] The deceleration control unit 89 performs temperature maintenance control to maintain the temperature of the SCR catalyst 43 within a predetermined high temperature range while preventing the SOC of the battery 26 from exceeding the upper limit value during a specific deceleration of the vehicle 10, for example, in a driving scenario of a long downhill slope. The deceleration control unit 89 performs at least the following first control or second control as the temperature maintenance control. · First control: When the SOC of the battery 26 is equal to or greater than a first predetermined value corresponding to the SOC upper limit value, the engine resistance of the engine 1 is increased so that the deceleration is greater than the required deceleration. Further, in accordance with the increase in the engine resistance, the motor 21 is made to execute a motor assist operation. This first control is executed even when the temperature of the SCR catalyst 43 is lower than the set temperature. · Second control: When the SOC of the battery 26 is a second predetermined value lower than the first predetermined value, the combustion state of the engine 1 is controlled to increase the temperature of the SCR catalyst 43. Further, the motor 21 is made to execute a regeneration operation.

[0070] When the vehicle 10 is decelerating and the SOC of the battery 26 is equal to or greater than the first predetermined value and the temperature of the SCR catalyst 43 is higher than the set temperature, the deceleration control unit 89 does not perform the above temperature maintenance control and performs the following third control or fourth control. · Third control: Clutch CL1 is engaged and motoring is performed to rotate the engine in a fuel cut state, generating engine resistance to decelerate using engine braking. · Fourth control: Clutch CL1 is released to disconnect engine 1 from the drive shaft of drive wheels 24, and deceleration is performed using regenerative braking based on the regenerative resistance of motor 21.

[0071] As control for increasing the temperature of SCR catalyst 43 executed in the above second control, deceleration control unit 89 causes fuel injection to be performed during the expansion stroke of engine 1. FIG. 4 is a graph showing the relationship between the fuel injection pattern by injector 9 of engine 1 and the in-cylinder heat generation rate (dQ / dθ). Heat generation rate characteristic H1 shown in FIG. 4 indicates the heat generation rate of typical combustion performed in engine body 2 during normal operation. Heat generation rate characteristic H1 has a large peak at a crank angle slightly retarded from TDC (top dead center of compression), indicating that a large engine torque can be generated.

[0072] The fuel injection pattern A1 shown in the lower part of the graph of FIG. 4 is the split injection pattern executed by injector 9 during normal operation. In fuel injection pattern A1, injection is mainly performed in the last half of the compression stroke and near TDC. By executing fuel injection with such a fuel injection pattern A1, it is possible to perform compression ignition combustion that exhibits heat generation rate characteristic H1 for generating engine torque.

[0073] Another heat generation rate characteristic H2 shown in FIG. 4 indicates the heat generation rate of combustion performed in the engine body 2 when the above temperature maintenance control is performed. In the heat generation rate characteristic H2, small peaks appear multiple times in the expansion stroke after TDC. That is, the heat generation rate characteristic H2 indicates that combustion with a small heat generation rate continues over the middle region from TDC to the expansion stroke. Even if combustion such as the heat generation rate characteristic H2 is performed in the engine body 2, substantially no engine torque is generated. However, it is possible to send out high-temperature exhaust gas accompanying combustion to the exhaust passage 40. Therefore, by executing the combustion of the heat generation rate characteristic H2, the SCR catalyst 43 can be heated or kept warm. That is, even without performing combustion that would generate engine torque during deceleration, the temperature of the SCR catalyst 43 can be maintained.

[0074] The fuel injection pattern A2 is a split injection pattern executed by the injector 9 during temperature maintenance control. In the fuel injection pattern A2, multiple fuel injections are performed over the region from near TDC to the middle region of the expansion stroke. The fuel injection near TDC is an injection for raising the in-cylinder temperature so that the fuel injected in the middle region of the expansion stroke burns without misfiring, and is not intended to generate engine torque.

[0075] When executing the fuel injection pattern A2 for maintaining the temperature of the SCR catalyst 43, it is desirable to control the exhaust turbo device 60 by the deceleration control unit 89 to increase the supercharging pressure. Specifically, the deceleration control unit 89 operates the VGT actuator 63 to adjust the angle of the nozzle vane so that the exhaust flow rate becomes faster. Thereby, the rotational speed of the compressor 61 can be increased and the supercharging pressure can be raised. When fuel injection is performed in the expansion stroke in which the piston 5 descends, the fuel tends to adhere to the inner wall of the cylinder 2a, that is, the cylinder liner. In this case, the fuel may enter the oil pan of the cylinder block 3, resulting in fuel dilution of the engine oil. Increasing the supercharging pressure shortens the flight distance of the fuel injected into the cylinder 2a, and as a result, fuel adhesion to the cylinder liner can be suppressed.

[0076] [Specific Example of Temperature Maintenance Control] FIG. 5 is a time chart showing the operations of the engine and the motor when temperature maintenance control is executed in the downhill driving mode of the vehicle. From the upper part of FIG. 5 in order, charts of the transmission speed, the catalyst temperature, the SOC, the bmep, and the motor torque are shown. A table showing the operating states of the clutch CL1, the engine 1, and the motor 21 is appended to the upper part of the chart.

[0077] The transmission speed (rpm) indicates the rotational speed of the rotating shaft of the automatic transmission 22. When the engine 1 is disconnected by releasing the clutch CL1, the transmission speed = the rotational speed of the motor 21 (mot_rev), and when the clutch CL1 is engaged, the transmission speed = mot_rev = the engine speed (NE). The catalyst temperature (° C.) is the temperature of the SCR catalyst 43 obtained by the catalyst temperature estimator 86.

[0078] The SOC is the remaining charge of the battery 26 obtained by the SOC calculator 87. In FIG. 5, SOC = 80% is exemplified as the first predetermined value which is the SOC upper limit value, and SOC = 75% is exemplified as the second predetermined value which is the threshold for switching the battery 26 from the discharge mode to the charge mode in the temperature maintenance control. The first predetermined value and the second predetermined value may be appropriately set according to the properties of the battery 26, the control concept, etc.

[0079] The bmep (Pa) is an index indicating the pressure of the engine brake of the engine 1. When bmep = 0 (Pa), the engine brake and the engine torque are in a zero state. In the negative region where bmep is 0 (Pa) or less, an engine brake is generated to decelerate the vehicle 10. In the positive region, an engine torque is generated to accelerate the vehicle 10. The motor torque (Nm) indicates the torque generated by the motor 21 and the regenerative brake. In the negative region where the motor torque is 0 (Nm) or less, a regenerative brake is generated, and in the positive region, the motor torque is generated.

[0080] Time T0 is a certain time when downhill driving has already been performed and the above-described fourth control is being executed. At time T0, the catalyst temperature is still higher than the set temperature, and the SOC is in a state lower than the first predetermined value (80%). The vehicle 10 is being decelerated by the regenerative brake. That is, the clutch CL1 is released, and the engine 1 is stopped (i-stop). Only the motor 21 connected to the drive shaft of the drive wheels 24 via the automatic transmission 22 generates a braking force corresponding to the regenerative resistance. After time T0, since the engine 1 is in a stopped state, the catalyst temperature will decrease, and since the motor 21 performs a regenerative operation, the SOC will increase.

[0081] Time T1 is the time when the SOC reaches the first predetermined value and is in a state where the control has shifted from the fourth control to the third control. The catalyst temperature is still higher than the set temperature. When time T1 is reached, the deceleration control unit 89 engages the clutch CL1 and rotates the engine 1 in a fuel cut state (F / C). As a result, an engine brake is generated as shown in the bmep chart. On the other hand, the deceleration control unit 89 controls the inverter 25 to stop the regenerative operation so as not to increase the SOC. Therefore, the vehicle 10 is in a state of being decelerated by the engine brake due to the motoring of the engine 1. After time T1, since the engine 1 is in a fuel cut state, the catalyst temperature will further decrease. The SOC is maintained at the first predetermined value.

[0082] Time T2 is the time when the SOC is at the first predetermined value and the catalyst temperature has decreased to the set temperature. When the state of time T2 is reached, the deceleration control unit 89 executes the above-described first control. That is, the deceleration control unit 89 increases the engine resistance of the engine 1 so that the deceleration becomes greater than the required deceleration derived by the required torque calculation unit 83. That is, a second engine resistance greater than the first engine resistance set at time T1 is set, and the engine brake is strengthened (displayed as "embrake strengthening" in the table of FIG. 5).

[0083] On the one hand, if the engine brake is strengthened more than necessary, the driver may feel uncomfortable in the decelerating state. To address this, in response to an increase in engine resistance, the motor 21 is made to execute a motor assist operation (displayed as "power running" in the table of FIG. 5). The deceleration control unit 89 instructs the motor control unit 82 to supply driving power to the motor 21 via the inverter 25 and generate a driving force in the motor 21. By such control, the increase in the engine brake can be offset by the motor torque based on the motor assist operation. Therefore, drivability can be maintained. Also, by supplying power to the motor 21, the SOC of the battery 26 is consumed, creating a state where regenerative braking can be utilized. That is, even when the catalyst temperature becomes the set temperature or lower, first, the battery 26 is discharged by the first control to give a margin to the SOC. After time T2, since the engine 1 continues to be in a state where combustion does not occur, the catalyst temperature further decreases. On the other hand, the SOC decreases from the first predetermined value.

[0084] In the first control, as a control for increasing engine resistance, for example, control for reducing the in-cylinder pressure of the cylinder 2a below the ambient environment to increase the operating resistance of the piston 5 can be exemplified. Specific examples include the operation of the intake shutter valve 33 and the operation of the opening timing of the intake valve 13. Creating a timing to close the intake shutter valve 33 makes the cylinder 2a in a semi-sealed state and increases the operating resistance of the piston 5. By retarding the opening timing of the intake valve 13 and creating a period of negative overlap where both the intake valve 13 and the exhaust valve 14 are closed, the cylinder 2a can also be sealed to increase the operating resistance of the piston 5. The increase in the operating resistance of the piston 5 leads to an increase in engine resistance, and the engine brake can be strengthened.

[0085] As another control for increasing engine resistance, control for downshifting the gear stage of the automatic transmission 22 can be exemplified. When an increase in engine resistance is required, the gear stage of the automatic transmission 22 is downshifted by one or more stages from the current gear stage to increase the engine speed. By increasing the engine speed, the engine resistance can be easily increased.

[0086] Time T3 is the time when the SOC has decreased to the second predetermined value (75%) and the catalyst temperature has decreased below the set temperature. When the deceleration control unit 89 reaches the state at time T3, it executes the second control described above. The deceleration control unit 89 gives an instruction to the engine control unit 81 so that the engine body 2 performs combustion for maintaining the temperature of the SCR catalyst 43. The engine control unit 81 causes the injector 9 to execute fuel injection in the fuel injection pattern A2 of FIG. 4 and performs combustion only for heating the catalyst. That is, the combustion state is controlled so that the load of the engine 1 becomes zero (displayed as "N / L" in the table of FIG. 5). By this control, as shown in the bmep chart, the engine brake disappears.

[0087] On the other hand, at time T3, since the SOC has decreased to the second predetermined value, it is possible to cause the motor 21 to perform a regeneration operation. By utilizing the margin of this SOC, that is, the difference between the first predetermined value and the second predetermined value, the motor 21 is caused to perform a regeneration operation to generate a regeneration brake. The deceleration control unit 89 gives an instruction to the motor control unit 82 so as to generate a regeneration resistance that can compensate for the disappearance of the engine brake. That is, the regeneration brake creates a deceleration corresponding to the engine brake.

[0088] As described above, if the SOC is equal to or higher than the first predetermined value, the deceleration control unit 89 performs the first control even when the catalyst temperature is lower than the set temperature. After that, when the SOC decreases to the second predetermined value by the execution of the first control, the control is switched to the second control. In this way, even when the catalyst temperature is lower than the set temperature, first, the battery 26 is discharged by the first control to provide a margin for the SOC, and then the SCR catalyst 43 is heated up by the subsequent second control, and the cooperative control is performed. In the first control, the deceleration torque that is excessively generated by strengthening the engine brake can be canceled by the motor torque generated by the motor assist operation. Further, in the second control following the first control, the deceleration rate corresponding to the engine brake can be created by the regenerative brake. Therefore, it is possible to maintain the drivability without giving a sense of discomfort to the driver during deceleration.

[0089] After time T3, since the engine body 2 performs combustion for maintaining the catalyst temperature, the catalyst temperature rises. On the other hand, since the motor 21 performs a regeneration operation, the SOC rises. Time T4 is the time when the SOC has recovered to the first predetermined value (80%) in a state where the deceleration of the vehicle 10 continues. In this case, the deceleration control unit 89 switches the control mode from the second control to the first control. That is, the deceleration control unit 89 generates an engine brake with the strengthened second engine resistance and generates a regenerative brake force so as to cancel the strengthened engine braking force. Thereby, it is possible to suppress the increase in the SOC while maintaining the drivability.

[0090] Thereafter, when time T5 is reached at which the SOC decreases to the second predetermined value (75%), the deceleration control unit 89 switches the control mode from the first control to the second control. Thereafter, during the deceleration operation of the vehicle 10, the first control and the second control are repeated according to the SOC of the battery 26. Therefore, for example, even when driving on a long downhill slope, it is possible to maintain the temperature of the SCR catalyst 43 without overcharging the battery 26.

[0091] [Example of Vehicle Deceleration Control] FIG. 6 is a flowchart showing an example of deceleration control in the downhill driving mode of the vehicle 10 by the processor 80. When the vehicle 10 is running, the processor 80 determines whether the vehicle 10 is running downhill (step S1). Whether it is running downhill can be determined based on measurement data such as the accelerator opening detected by the accelerator opening sensor SN10, the vehicle speed and acceleration of the vehicle 10 based on the detection result of the crank angle sensor SN1, and the decrease in the intake pressure accompanying the self-weight running of the vehicle detected by the intake pressure sensor SN4.

[0092] When it is determined that the vehicle is not running downhill (NO in step S1), the processor 80 causes other driving modes to be executed in accordance with the engine control algorithm based on the detection results of various sensors (step S2). On the other hand, when it is determined that the vehicle is running downhill (YES in step S1), the deceleration control unit 89 of the processor 80 stops the engine 1 via the engine control unit 81 (step S3). Further, the deceleration control unit 89 performs control to release the clutch CL1 and decelerates the vehicle 10 by the regenerative brake of the motor 21 (step S4). The state of this step S4 corresponds to the state at time T0 in the time chart of FIG. 5.

[0093] Next, the deceleration control unit 89 determines whether the SOC of the battery 26 has reached or exceeded a first predetermined value (exemplified as SOC = 80% in FIG. 5) based on the output value of the SOC calculation unit 87 (step S5). When the SOC is equal to or higher than the first predetermined value (YES in step S5), if the regenerative operation of the motor 21 is continued, the battery 26 will be overcharged. Therefore, the deceleration control unit 89 decelerates the vehicle 10 using the engine brake instead of the regenerative brake.

[0094] Specifically, the deceleration control unit 89 performs control to engage the clutch CL1 and connects the engine 1 to the drive shaft of the drive wheels 24 (step S6). However, the deceleration control unit 89 rotates the engine in a fuel cut state where fuel supply from the injector 9 is not performed, and performs motoring (step S7). The state of step S4 corresponds to the state at time T1 in the time chart of FIG. 5.

[0095] Subsequently, the deceleration control unit 89 determines whether or not the catalyst temperature of the SCR catalyst 43 (hereinafter referred to as the SCR temperature) is equal to or lower than a predetermined set temperature based on the output value of the catalyst temperature estimation unit 86 (step S8). When the SCR temperature is lower than the set temperature (YES in step S8), the deceleration control unit 89 executes catalyst temperature maintenance control to maintain the temperature of the SCR catalyst 43 (step S11). On the other hand, when the SCR temperature is higher than the set temperature (NO in step S8), the deceleration control unit 89 continues the motoring in step S7.

[0096] In step S5, when the SOC is less than the first predetermined value (NO in step S5), the deceleration control unit 89 determines whether or not the SCR temperature is equal to or lower than the set temperature (step S9). When the SCR temperature is higher than the set temperature (NO in step S9), there is a margin in both the SOC and the SCR temperature. Therefore, the process returns to step S4, and the deceleration of the vehicle 10 by the regenerative brake is continued. On the other hand, when the SCR temperature is lower than the set temperature (YES in step S9), the deceleration control unit 89 performs control to engage the clutch CL1 and connects the engine 1 to the drive shaft of the drive wheels 24 (step S10). Then, the deceleration control unit 89 executes catalyst temperature maintenance control (step S11).

[0097] FIG. 7 is a flowchart showing an example of the catalyst temperature maintenance control by the deceleration control unit 89. The deceleration control unit 89 determines whether or not the SOC of the battery 26 is equal to or greater than a first predetermined value (step S21). When the SOC is equal to or greater than the first predetermined value (YES in step S21), the deceleration control unit 89 decides to execute the above-described first control (step S22). When the SOC is less than the first predetermined value (NO in step S21), the deceleration control unit 89 decides to execute the above-described second control (step S23).

[0098] In the first control, the deceleration control unit 89 forms a deceleration torque greater than the required deceleration rate derived by the required torque calculation unit 83 (step S24). Specifically, the deceleration control unit 89 causes any one or a plurality of means among closing of the intake shutter valve 33, retarding the opening timing of the intake valve 13, and downshifting of the gear stage of the automatic transmission 22 to be executed. Thereby, the engine resistance can be increased and the engine brake can be strengthened. Arrow C1 in FIG. 5 corresponds to the strengthening of the engine brake in step S24.

[0099] Furthermore, the deceleration control unit 89 causes the motor 21 to execute a motor assist operation (step S25). That is, the motor torque calculation unit 85 calculates a motor torque corresponding to the increase in the above-described engine resistance. The deceleration control unit 89 gives an instruction to the motor control unit 82 so that the calculated motor torque is generated by the motor 21. Arrow C2 in FIG. 5 corresponds to the generation of the motor torque in step S25. By this control, since the increase in the engine brake is canceled by the motor torque, the driver does not feel a sense of discomfort such as a sudden change in the deceleration feeling. The timing at which the controls of steps S24 and S25 are started corresponds to the time T2 in the time chart of FIG. 5.

[0100] Subsequently, the deceleration control unit 89 determines whether the SOC of the battery 26 has reached a predetermined second value (exemplified as SOC = 75% in FIG. 5) or is below the second value based on the output value of the SOC calculation unit 87 (step S26). When the SOC is equal to or lower than the second value (YES in step S26), the SOC has a margin such that the battery 26 can be operated in the charging mode. In this case, the deceleration control unit 89 executes a second control to cause the engine 1 to perform no-load combustion to increase the temperature of the SCR catalyst 43 and cause the motor 21 to perform a regeneration operation. The case of YES in step S26 and the case determined to execute the second control in step S23 are synonymous in terms of control.

[0101] Specifically, the deceleration control unit 89 causes the injector 9 to perform fuel injection for causing the engine 1 to perform no-load combustion as shown in the fuel injection pattern A2 of FIG. 4 via the engine control unit 81 (step S7). By this control, combustion gas flows through the exhaust passage 40, and the heating of the SCR catalyst 43 is started. On the other hand, the engine brake disappears due to engine combustion. Therefore, the deceleration control unit 89 causes the motor torque calculation unit 85 to calculate the required motor torque in order to cover the deceleration torque corresponding to the current required deceleration with the regenerative brake. Then, the deceleration control unit 89 causes the motor 21 to perform a regeneration operation so as to generate a regenerative torque corresponding to the calculated motor torque (step S28).

[0102] The timing at which the control of steps S27 and S28 is started corresponds to the time T3 in FIG. 5. The arrow C3 in FIG. 5 corresponds to the transition from the motor assist operation to the regeneration operation in step S28. Thereafter, if deceleration end is not detected (NO in step S29), the process returns to step S21 and the process is repeated. On the other hand, when deceleration end is detected, the deceleration control unit 89 ends the catalyst temperature maintenance control.

Explanation of Signs

[0103] 1 Engine 2 Engine body 7 Crankshaft (output shaft) 10 Vehicle 21 Motor 22 Automatic Transmission 24 Driving Wheel 26 Battery 40 Exhaust Passage (Exhaust System) 43 SCR Catalyst (Catalyst) 60 Exhaust Turbocharger (Supercharger) 80 Processor (Vehicle Control Device) 89 Deceleration Control Unit 89 (Control Unit) C Combustion Chamber CL1 Clutch

Claims

1. A vehicle control device comprising an engine that generates a driving force for driving drive wheels of a vehicle, an exhaust system having a combustion chamber and a catalyst, a motor capable of driving the drive wheels, a control unit that controls the operation of the vehicle, including a battery that supplies driving power to the motor in a motor assist operation in which the motor drives the drive wheels and is charged in a regeneration operation in which the motor generates electricity, wherein the control unit, when the vehicle decelerates, in a first control, when the state of charge (SOC) of the battery is equal to or higher than a first predetermined value, increases engine resistance so that the deceleration becomes greater than a required deceleration, and executes the motor assist operation according to an increase in the engine resistance, or in a second control, when the SOC of the battery is equal to a second predetermined value lower than the first predetermined value, controls the combustion state of the engine to increase the temperature of the catalyst and executes the regeneration operation.

2. The vehicle control device according to claim 1, wherein the control unit performs the first control even when the temperature of the catalyst is lower than a set temperature, and switches to the second control when the SOC decreases to the second predetermined value by execution of the first control.

3. The vehicle control device according to claim 2, wherein the vehicle further includes a clutch that changes a torque transmission state between an output shaft of the engine and a drive shaft of the drive wheels, and the control unit in a third control, when the SOC is equal to or higher than the first predetermined value and the temperature of the catalyst is higher than a set temperature in a state where the clutch is released to disconnect the engine from the drive shaft and the vehicle is decelerated by the regeneration resistance of the motor, engages the clutch and rotates the engine in a fuel cut state to generate a first engine resistance. A control device for a vehicle that, when the temperature of the catalyst becomes lower than a set temperature during the execution of the third control, performs the first control with a second engine resistance that is greater than the first engine resistance.

4. In the vehicle control device according to claim 2, after switching to the second control, when the SOC becomes equal to or higher than the first predetermined value in a state where the deceleration of the vehicle continues, the control unit switches to the first control. A control device for a vehicle.

5. In the vehicle control device according to any one of claims 1 to 4, the control unit controls the combustion state so that the load on the engine becomes zero in the second control. A control device for a vehicle.

6. In the vehicle control device according to claim 2, the control unit sets the regeneration resistance of the motor in the second control so as to compensate for the disappearance of the engine resistance due to the switching from the first control to the second control. A control device for a vehicle.

7. In the vehicle control device according to any one of claims 1 to 4, the control unit executes control to decrease the in-cylinder pressure of the engine below the ambient environment to increase the piston resistance as control to increase the engine resistance. A control device for a vehicle.

8. In the vehicle control device according to any one of claims 1 to 4, the vehicle includes a transmission between the drive shafts of the drive wheels of the engine and the motor, and the control unit performs control to downshift the gear stage of the transmission as control to increase the engine resistance. A control device for a vehicle.

9. In the vehicle control device according to any one of claims 1 to 4, The control unit is a vehicle control device that causes fuel injection to be performed during the expansion stroke of the engine as control for raising the temperature of the catalyst.

10. In the vehicle control device according to claim 9, The vehicle includes a supercharger that supercharges the air supplied to the combustion chamber of the engine, The control unit is a vehicle control device that controls the supercharger so as to increase the supercharging pressure when controlling to raise the temperature of the catalyst.

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