Hybrid vehicle control device

Abstract

To suppress a battery from overdischarging.SOLUTION: An electronic control unit 100 executes: a driving force switching process for making braking torque that is generated by a driving system during deceleration of a vehicle smaller when a fuel cut process in an engine 10 provided with a filter device that captures PMs being exhausted is prohibited from being executed, more than when the process is not prohibited from being executed; a motoring process for burning and purifying the PMs captured by the filter device by making a first rotary electric machine rotate and drive the engine 10 during deceleration of the vehicle; and a setting process for setting a vehicle speed, at which execution of the motoring process is permitted, to a higher speed when the execution of the fuel cut process is prohibited than when the execution is not prohibited.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a control device for a hybrid vehicle. [Background technology]

[0002] Some hybrid vehicles are equipped with engines equipped with a filter device that captures particulate matter in the exhaust. If a fuel cut is performed on the engine when a large amount of particulate matter has accumulated on the filter device, the accumulated particulate matter may burn all at once, causing the filter device to overheat. Therefore, as described in Patent Document 1, if the amount of particulate matter accumulated on the filter device exceeds a certain amount, the engine fuel cut may be prohibited.

[0003] On the other hand, when fuel cut is prohibited, the braking torque generated by the engine during deceleration, known as engine braking, is reduced. As a result, the vehicle's deceleration decreases, which may cause discomfort to the occupants. The decrease in vehicle deceleration due to the reduction in engine braking can be compensated for by increasing the amount of regenerative braking. However, increasing the amount of regenerative braking can disrupt the balance between charging and discharging, which may result in overcharging the battery. For this reason, the control device described in Patent Document 1 performs a driving force switching process that reduces the deceleration of the hybrid vehicle more than when fuel cut is not prohibited when fuel cut is prohibited. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-128152 Summary of the Invention [Problem to be solved by the invention]

[0005] While the vehicle is decelerating, motoring, which rotates the engine using a motor, may be performed to regenerate the filter device. Reducing the vehicle's deceleration through the driving force switching process reduces the amount of power generated through regeneration. Therefore, if the regeneration process is performed while the deceleration is reduced, the power consumption for motoring may far exceed the amount of power generated through regeneration, potentially resulting in over-discharge of the battery. [Means for solving the problem]

[0006] A hybrid vehicle control device that solves the above problem controls a hybrid vehicle provided with a drivetrain having an engine equipped with a filter device that traps particulate matter in the exhaust, a first rotating electric machine that generates rotational force to be applied to the engine in response to power supplied from a battery, and a second rotating electric machine that generates electricity by receiving rotational force transmitted from the wheels. The control device performs the following operations during deceleration of the hybrid vehicle: a fuel cut-off process that cuts fuel to the engine to generate engine braking; a driving force switching process that, when the fuel cut-off process is prohibited, reduces the braking torque generated by the drivetrain during deceleration of the hybrid vehicle compared to when the fuel cut-off process is not prohibited; a motoring process that, when the hybrid vehicle decelerates, rotates the engine using the first rotating electric machine to combust and purify the particulate matter trapped in the filter device; and a setting process that, when the fuel cut-off process is prohibited, sets the vehicle speed at which the motoring process is permitted to be performed to a speed higher than when the fuel cut-off process is not prohibited.

[0007] If the motoring process is performed at the same vehicle speed range while the fuel cut process is prohibited and the braking torque is reduced by the driving force switching process, the amount of regenerative power generated by the second rotating electric machine during the motoring process will decrease due to the reduction in braking torque. In the above control device, when the fuel cut process is prohibited, the motoring process is performed at a higher vehicle speed range than when the fuel cut process is not prohibited. Therefore, the decrease in the amount of regenerative power generated during the motoring process when the fuel cut process is prohibited is suppressed. Therefore, the above control device for a hybrid vehicle has the effect of suppressing over-discharge of the battery due to the motoring process.

[0008] The electric power stored in the battery is also supplied to parts other than the drivetrain of the hybrid vehicle. When the motoring process is performed while the electric power consumption of these parts is high, and the electric power consumption for driving the engine by the first rotating electric machine is added, the battery is likely to be over-discharged. Therefore, it is desirable that the control device of the hybrid vehicle be configured to prohibit the motoring process when the amount of discharge of the battery is equal to or greater than a predetermined judgment value.

[0009] If a fuel cut process is performed when the amount of particulate matter accumulated in the filter device is large, the filter device may overheat due to heat generated by combustion of the particulate matter. Therefore, it is desirable that the control device for the hybrid vehicle be configured to prohibit the fuel cut process when the amount of particulate matter accumulated in the filter device is equal to or greater than a predetermined threshold value. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram schematically illustrating a configuration of a drive system of a hybrid vehicle to which a control device of an embodiment is applied; [Figure 2] FIG. 2 is a diagram schematically illustrating a configuration of the control device. [Figure 3] 4 is a graph showing a setting manner of a target drive torque of the control device. [Figure 4] 3 is a flowchart of a regeneration request determination routine executed by the control device. [Figure 5] 4 is a flowchart of a motoring processing routine executed by the control device. [Figure 6] 4 is a graph showing a setting manner of the motoring permitted vehicle speed of the control device. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of a control device for a hybrid vehicle will be described in detail below with reference to FIGS. <Hybrid vehicle drivetrain> First, the configuration of a drivetrain of a hybrid vehicle to which the control device of this embodiment is applied will be described with reference to Figure 1. The drivetrain of this hybrid vehicle is provided with an engine 10, a first rotating electric machine 71, and a second rotating electric machine 72. The engine 10 is an internal combustion engine that generates power by burning fuel. The first rotating electric machine 71 and the second rotating electric machine 72 function as electric motors that generate power by receiving power from an electric power source, and as generators that generate power by receiving power from an external source.

[0012] 1 is further provided with a battery 77, a first inverter 75, and a second inverter 76. The first inverter 75 converts the DC current discharged from the battery 77 into AC current and supplies it to the first rotating electric machine 71. The first inverter 75 also converts the AC current generated by the first rotating electric machine 71 into DC current and charges the battery 77. The second inverter 76 converts the DC current discharged from the battery 77 into AC current and supplies it to the second rotating electric machine 72. The second inverter 76 also converts the AC current generated by the second rotating electric machine 72 into DC current and charges the battery 77.

[0013] The engine 10 has a plurality of cylinders 11 that combust an air-fuel mixture. The engine 10 is also provided with an intake passage 15 that serves as a passage through which air is introduced to each cylinder 11. The intake passage 15 is provided with a throttle valve 16, which is a valve for adjusting the flow rate of intake air. The portion of the intake passage 15 downstream of the throttle valve 16 is branched off for each cylinder. An injector 17 is provided at each branched portion of the intake passage 15 for each cylinder. Meanwhile, each cylinder 11 is provided with an ignition device 18 that ignites the air-fuel mixture introduced into the cylinder 11 by spark discharge. The engine 10 is also provided with an exhaust passage 21 that serves as a discharge passage for exhaust gas generated by the combustion of the air-fuel mixture in each cylinder 11. A three-way catalytic device 22 that purifies the exhaust gas is provided in the exhaust passage 21. Furthermore, a filter device 23 that collects particulate matter (PM) in the exhaust gas is provided downstream of the three-way catalytic device 22 in the exhaust passage 21.

[0014] An air-fuel mixture containing fuel injected by an injector 17 is introduced into each cylinder 11 of the engine 10 through an intake passage 15. When an ignition device 18 ignites this air-fuel mixture, combustion occurs in the cylinder 11. Exhaust gas produced by this combustion is discharged from the cylinder 11 into an exhaust passage 21. In this engine 10, a three-way catalytic device 22 oxidizes HC and CO in the exhaust gas and reduces NOx, and a filter device 23 captures PM in the exhaust, thereby purifying the exhaust gas.

[0015] On the other hand, the hybrid vehicle is provided with a first planetary gear mechanism 40. The first planetary gear mechanism 40 has a sun gear 41, which is an external gear, and a ring gear 42, which is an internal gear, arranged coaxially with the sun gear 41. A plurality of pinion gears 43 are arranged between the sun gear 41 and the ring gear 42, and mesh with both the sun gear 41 and the ring gear 42. Each pinion gear 43 is supported by a carrier 44 in a state in which it can freely rotate and revolve. The sun gear 41, the ring gear 42, and the carrier 44 constitute three rotating elements of the first planetary gear mechanism 40. The carrier 44 of the first planetary gear mechanism 40 is connected to the crankshaft 14, which is the output shaft of the engine 10, and the sun gear 41 is connected to a first rotating electric machine 71. A drive shaft 45 is connected to the ring gear 42. Wheels 62 are connected to the drive shaft 45 via a reduction mechanism 60, a differential mechanism 61, and wheel axles 63. That is, the drive shaft 45 is a shaft for extracting power to the wheels 62 .

[0016] A second rotating electric machine 72 is connected to the drive shaft 45 via a second planetary gear mechanism 50. The second planetary gear mechanism 50 has a sun gear 51, which is an external gear, and a ring gear 52, which is an internal gear, arranged coaxially with the sun gear 51. A plurality of pinion gears 53 are arranged between the sun gear 51 and the ring gear 52, and mesh with both the sun gear 51 and the ring gear 52. Each pinion gear 53 is rotatable on its own axis but is unable to revolve. The ring gear 52 of the second planetary gear mechanism 50 is connected to the drive shaft 45, and the second rotating electric machine 72 is connected to the sun gear 51. The second planetary gear mechanism 50 functions as a reduction mechanism that reduces the rotation of the second rotating electric machine 72 and transmits it to the drive shaft 45.

[0017] <Control device configuration> Next, the configuration of the control device for the hybrid vehicle of this embodiment will be described with reference to FIG.

[0018] A hybrid vehicle is equipped with an electronic control unit 100 as a control device. The electronic control unit 100 includes a processing unit 101 that executes various processes for vehicle control, and a storage unit 102 that stores programs and data for vehicle control. In reality, the electronic control unit 100 is composed of multiple control units for engine control, battery control, etc.

[0019] The hybrid vehicle is equipped with sensors such as an air flow meter 103, a crank angle sensor 104, an air-fuel ratio sensor 105, an accelerator pedal sensor 106, a shift position sensor 107, and a vehicle speed sensor 108. The air flow meter 103 is a sensor that detects the intake air amount GA of the engine 10. The crank angle sensor 104 is a sensor that detects the rotational phase of the crankshaft 14. The air-fuel ratio sensor 105 is a sensor that detects the air-fuel ratio of the mixture burned in the cylinder 11. The accelerator pedal sensor 106 is a sensor that detects the accelerator pedal operation amount ACC by the driver. The shift position sensor 107 is a sensor that detects the operation position of the shift lever by the driver. The vehicle speed sensor 108 is a sensor that detects the vehicle speed V of the hybrid vehicle.

[0020] Detection signals from these sensors are input to an electronic control unit 100. The electronic control unit 100 then executes various controls for the hybrid vehicle based on the detection results of these sensors. For example, the electronic control unit 100 controls the operation of the engine 10 through control of a throttle valve 16, an injector 17, an ignition device 18, etc. The electronic control unit 100 also controls the torque of the first rotating electric machine 71 and the second rotating electric machine 72 through control of a first inverter 75 and a second inverter 76.

[0021] <Driving control of hybrid vehicles> The electronic control unit 100 configured as described above performs driving control of the hybrid vehicle based on input detection signals and information. During driving control, the electronic control unit 100 sets a value for the target drive torque T* based on the accelerator pedal depression amount ACC, the vehicle speed V, and the like. The target drive torque T* represents a target value for the torque of the drive shaft 45 generated by the drive train. The electronic control unit 100 then controls the torque of the engine 10, the first rotating electric machine 71, and the second rotating electric machine 72 so that the torque of the drive shaft 45 generated by the drive train has a value equal to the target drive torque T*. At this time, the electronic control unit 100 determines the distribution of torque generated by the engine 10, the first rotating electric machine 71, and the second rotating electric machine 72 based on the efficiency of the engine 10 and the charge state of the battery 77.

[0022] <Fuel cut processing> The electronic control unit 100 may set a negative value as the value of the target drive torque T* when the hybrid vehicle is decelerating. Here, deceleration of the hybrid vehicle refers to when the hybrid vehicle is coasting. At this time, the electronic control unit 100 controls the torque of the engine 10, the first rotating electric machine 71, and the second rotating electric machine 72 so that the drivetrain generates a braking torque on the drive shaft 45. If the braking torque at this time were generated solely through regenerative braking of the second rotating electric machine 72, the battery 77 may be overcharged. In such a case, the electronic control unit 100 performs a fuel cut process to stop fuel injection from the injector 17, thereby generating engine braking. That is, at this time, the engine 10 is rotated by the rotational force transmitted from the drive shaft 45. The engine 10 generates a braking torque that slows down the rotation of the drive shaft 45 due to friction loss and pumping loss.

[0023] As described above, the engine 10 is equipped with the filter device 23 that captures PM in the exhaust gas. When a fuel cut is performed, the gas in the exhaust passage 21 is replaced with fresh air, causing a large amount of oxygen to flow into the filter device 23. This oxygen then combusts the PM captured in the filter device 23. Therefore, if a fuel cut is performed when a large amount of PM has been captured, there is a risk that the temperature of the filter device 23 will rise above the allowable upper limit due to heat generated by the combustion of the PM.

[0024] Meanwhile, the electronic control unit 100 estimates the amount of PM accumulated in the filter device 23 based on the operating conditions of the engine 10. If the amount of PM accumulated exceeds a predetermined threshold, the electronic control unit 100 prohibits the execution of fuel cut processing. Note that the electronic control unit 100 indicates that fuel cut is prohibited by setting an FC prohibition flag.

[0025] <Driving force switching process> As described above, the electronic control unit 100 sets a negative value as the target drive torque T* during deceleration and generates braking torque in the drivetrain. When the fuel cut process is prohibited, the engine braking effect is weakened, and this must be compensated for by the regenerative braking of the second rotating electric machine 72. On the other hand, if the amount of regenerative power generated by the second rotating electric machine 72 becomes excessive, there is a risk that the battery 77 will be overcharged. Therefore, when the fuel cut process is prohibited, the electronic control unit 100 performs a drive force switching process to reduce the braking torque generated in the drivetrain during deceleration of the hybrid vehicle. Note that once the electronic control unit 100 reduces the braking torque during deceleration in the drive force switching process, it maintains this state until the end of the trip. In other words, when the fuel cut process is prohibited in the drive force switching process, even if the fuel cut process is subsequently permitted, the reduced braking torque is maintained until the end of the trip. In the following description, the state in which the braking torque during deceleration is reduced by the driving force switching process will be referred to as "driving force switching", and the state in which the braking torque is not reduced will be referred to as "normal".

[0026] FIG. 3 shows the control flow of the electronic control unit 100. Target driving torque T* Fig. 3 shows the vehicle speed and the acceleration / deceleration ratio when the accelerator pedal depression amount ACC is 25%, 50%, 75%, and 100%. Target driving torque T* In addition, Fig. 3 shows the relationship between the vehicle speed and the fuel cutoff time when the accelerator pedal depression amount ACC is 0% and when fuel cut is prohibited and permitted. Target driving torque T* As shown in the figure, when the accelerator pedal operation amount ACC is 25% or more, Target driving torque T* On the other hand, when the accelerator pedal operation amount ACC is 0%, that is, when the hybrid vehicle is decelerating, if the vehicle speed becomes higher than a certain level, Target driving torque T* Furthermore, when the accelerator pedal operation amount ACC is 0%, a value larger than normal is set as the value of Target driving torque T* is set as the value of

[0027] <Filter regeneration> The filter device 23 installed in the engine 10 may become clogged with trapped PM. When the amount of PM accumulated in the filter device 23 exceeds a certain amount, the electronic control unit 100 performs filter regeneration to purify the accumulated PM. During filter regeneration, the electronic control unit 100 performs a motoring process in which the first rotating electric machine 71 rotates the engine 10 while combustion in the engine 10 is stopped, such as when the hybrid vehicle is decelerating. When the motoring process is performed, the exhaust gas flowing through the exhaust passage 21 is replaced with fresh air, and oxygen is supplied to the filter device 23. The supplied oxygen then combusts and purifies the PM accumulated in the filter device 23.

[0028] Even during the fuel cut process, oxygen is supplied to the filter device 23 to burn PM. However, it is difficult to control the duration of the fuel cut process and the amount of oxygen supplied to the filter device 23 during the process, and it is desirable to prohibit the process in order to reliably avoid overheating of the filter device 23 even when the amount of PM accumulation is large. In contrast, during the motoring process, the engine 10 is rotated by the first rotating electric machine 71, and it is easier to control the duration of the process and the amount of oxygen supplied to the filter device 23 during the process than during the fuel cut process. Therefore, when the amount of PM accumulation is large and there is concern that the filter device 23 may overheat during regeneration, it is desirable to prohibit the fuel cut process and regenerate the filter device 23 through the motoring process.

[0029] A flowchart of a regeneration request determination routine for determining whether or not filter regeneration is required is shown in Figure 4. The electronic control unit 100 repeatedly executes this routine at predetermined control intervals while the hybrid vehicle is running.

[0030] When the processing of this routine starts, the electronic control unit 100 first determines in step S100 whether the discharge amount of the battery 77 is less than a predetermined judgment value X2. More specifically, in step S110, the electronic control unit 100 determines whether the balance of charge and discharge of the battery 77 over a predetermined period up to the present is biased toward discharge. If the discharge amount of the battery 77 is equal to or greater than the judgment value X2 (NO), the electronic control unit 100 clears the regeneration request flag in step S110. Furthermore, the electronic control unit 100 ends the processing of this routine for the current control cycle. The regeneration request flag, when set, is a flag that indicates that filter regeneration is requested.

[0031] If the discharge amount of the battery 77 is less than the judgment value X2 (S100: YES), the electronic control unit 100 proceeds to step S120. Then, in step S120, the electronic control unit 100 determines whether or not the regeneration request flag is set. If the regeneration request flag is set (YES), the electronic control unit 100 ends the processing of this routine for the current control cycle. On the other hand, if the regeneration request flag is not set (NO), the electronic control unit 100 proceeds to step S130.

[0032] In step S130, the electronic control unit 100 determines whether the amount of PM accumulated in the filter device 23 is equal to or greater than a predetermined judgment value X1. The electronic control unit 100 estimates the amount of PM accumulated based on the operating conditions of the engine 10. The judgment value X1 is set to a value that is smaller than the amount of PM accumulated when the filter device 23 becomes clogged. If the amount of PM accumulated is less than the judgment value X1 (NO), the electronic control unit 100 ends the processing of this routine for the current control cycle. On the other hand, if the amount of PM accumulated is equal to or greater than the judgment value X1 (YES), the electronic control unit 100 proceeds to step S140. Then, the electronic control unit 100 sets a regeneration request flag in step S140, and then ends the processing of this routine for the current control cycle.

[0033] 5 shows a flowchart of a filter regeneration routine executed by the electronic control unit 100 to perform filter regeneration. This routine is also a process that is repeatedly executed by the electronic control unit 100 at predetermined control intervals while the hybrid vehicle is running.

[0034] When this routine starts, the electronic control unit 100 first determines whether the regeneration request flag is set in step S200. If the regeneration request flag is set (YES), the electronic control unit 100 proceeds to step S210, and if the regeneration request flag is not set (NO), the electronic control unit 100 ends the processing of this routine for the current control cycle.

[0035] In step S210, the electronic control unit 100 determines whether the hybrid vehicle is decelerating. For example, the electronic control unit 100 determines that the hybrid vehicle is decelerating when the accelerator pedal operation amount ACC is "0" and the vehicle speed is equal to or greater than a certain speed. If the electronic control unit 100 determines that the hybrid vehicle is decelerating (YES), the electronic control unit 100 proceeds to step S220, and if the hybrid vehicle is not decelerating (NO), the electronic control unit 100 ends the processing of this routine for the current control cycle.

[0036] In step S220, the electronic control unit 100 determines whether or not the driving force is being switched. That is, in step S220, the electronic control unit 100 determines whether or not the braking torque generated by the drivetrain during deceleration is being reduced by the driving force switching process. Then, the electronic control unit 100 proceeds to step S230 when the driving force is being switched, and proceeds to step S240 under normal circumstances.

[0037] In step S230, the electronic control unit 100 calculates the motoring permission vehicle speed VM based on the battery SOC using a first calculation map MAP1 pre-stored in the storage device 102. The battery SOC represents the state of charge (State of Charge) of the battery 77. Meanwhile, in step S240, the electronic control unit 100 calculates the motoring permission vehicle speed VM based on the battery SOC using a second calculation map MAP2 pre-stored in the storage device 102. That is, the electronic control unit 100 calculates the motoring permission vehicle speed VM using different calculation maps when driving force is switched and when the vehicle is normally driven.

[0038] 6 shows the relationship between the battery SOC and the motoring permission vehicle speed VM in each of the first calculation map MAP1 and the second calculation map MAP2. In both calculation maps, when the battery SOC is low, a higher vehicle speed is set as the value of the motoring permission vehicle speed VM than when the battery SOC is high. However, when the battery SOC is the same, a higher vehicle speed is set as the value of the motoring permission vehicle speed VM in the first calculation map MAP1 used when driving force is switched than in the second calculation map MAP2 used normally.

[0039] After calculating the motoring permission vehicle speed VM in step S230 or S240, the electronic control unit 100 proceeds to step S250. In step S250, the electronic control unit 100 determines whether the vehicle speed is equal to or greater than the motoring permission vehicle speed VM. If the vehicle speed is less than the motoring permission vehicle speed VM (NO), the electronic control unit 100 ends the processing of this routine for the current control cycle. On the other hand, if the vehicle speed is equal to or greater than the motoring permission vehicle speed VM (YES), the electronic control unit 100 proceeds to step S260.

[0040] In step S260, the electronic control unit 100 starts the motoring process. Then, the electronic control unit 100 ends the motoring process when any of the following first to third cases occurs. In the first case, the regeneration of the filter device 23 is completed. In the second case, the hybrid vehicle is stopped or accelerates again and is no longer decelerating. In the third case, the temperature of the filter device 23 reaches or exceeds a certain temperature. In the first case, that is, when the regeneration of the filter device 23 is completed, the electronic control unit 100 clears the regeneration request flag.

[0041] The electronic control unit 100 determines the completion of regeneration of the filter device 23, for example, in the following manner. When making this determination, the electronic control unit 100 calculates the execution time of the motoring process required to burn the PM of the accumulated amount based on the PM accumulated amount at the start of the motoring process. Then, the electronic control unit 100 determines that the regeneration of the filter device 23 is completed when the calculated time has elapsed since the start of the motoring process.

[0042] <Effects of the embodiment> The operation and effects of this embodiment will be described. The electronic control unit 100 sets a regeneration request flag when the discharge amount of the battery 77 is less than the judgment value X2 and the PM accumulation amount is equal to or greater than the regeneration request judgment value X1. When the regeneration request flag is set, the electronic control unit 100 permits the execution of motoring processing if the hybrid vehicle is decelerating and the vehicle speed is equal to or greater than the motoring permission vehicle speed VM. Note that the electronic control unit 100 sets a higher vehicle speed as the motoring permission vehicle speed VM as the value for the battery SOC.

[0043] During the motoring process, the engine 10 is driven to rotate by the first rotating electric machine 71. Therefore, during the motoring process, power is consumed for the power running of the first rotating electric machine 71. Meanwhile, the motoring process is performed while the hybrid vehicle is decelerating. During the deceleration of the hybrid vehicle, the second rotating electric machine 72 generates braking torque through regenerative power generation. If the amount of power consumed by the first rotating electric machine 71 during the motoring process greatly exceeds the amount of regenerative power generated by the second rotating electric machine 72, the power stored in the battery 77 may be drawn, resulting in over-discharge of the battery 77. Note that when the battery SOC is high, the amount of power that the battery 77 can discharge before over-discharge occurs is greater than when the battery SOC is low.

[0044] The electronic control unit 100 permits the motoring process to be performed on the condition that the vehicle speed is equal to or greater than the motoring permission vehicle speed VM. When the battery SOC is low, the electronic control unit 100 sets a higher vehicle speed VM as the value of the motoring permission vehicle speed VM than when the battery SOC is high. In other words, when the battery SOC is low, the electronic control unit 100 performs the motoring process at a higher vehicle speed range than when the battery SOC is high. On the other hand, the amount of regenerative power generated by the second rotating electric machine 72 during deceleration increases as the vehicle speed increases. Therefore, the motoring process can be performed without over-discharging the battery 77.

[0045] On the other hand, the electronic control unit 100 prohibits the execution of the fuel cut process when the amount of PM accumulation in the filter device 23 is equal to or greater than the determination value X1. When the execution of the fuel cut process is prohibited in the driving force switching process, the electronic control unit 100 reduces the braking torque generated by the drive train during deceleration of the hybrid vehicle until the end of the trip. Note that, since the engine 10 cannot generate braking torque during the motoring process, the braking torque of the drive train is generated by regenerative power generation of the second rotating electric machine 72.

[0046] When the braking torque generated by the drivetrain during deceleration is reduced by the driving force switching process, the amount of regenerative power generated by the second rotating electric machine 72 during motoring processing decreases. In response to this, the electronic control unit 100 sets a higher vehicle speed than normal as the value of the motoring permitted vehicle speed VM when driving force switching is performed. Therefore, when driving force switching is performed, the vehicle speed range in which motoring processing is performed becomes a vehicle speed range higher than normal.

[0047] According to the control device for a hybrid vehicle of the present embodiment described above, the following effects can be achieved. (1) When the fuel cut process is performed, oxygen is supplied to the filter device 23, causing the accumulated PM to burn. If the fuel cut process is performed when the amount of PM accumulation is large, a large amount of PM is burned in the filter device 23, and the heat generated by the combustion may cause the filter device 23 to overheat. In response to this, the electronic control unit 100 in this embodiment prohibits the execution of the fuel cut process when the amount of PM accumulation in the filter device 23 is equal to or greater than the determination value X1. This makes it difficult for the filter device 23 to overheat.

[0048] (2) When fuel cut is prohibited, the effectiveness of the engine brake weakens during deceleration of the hybrid vehicle. Therefore, if the braking torque generated by the drivetrain of the hybrid vehicle is maintained the same when fuel cut is prohibited as when fuel cut is not prohibited, the amount of regenerative power generated by the second rotating electric machine 72 may increase, causing the battery 77 to be overcharged. In response to this, the electronic control unit 100 in this embodiment performs a driving force switching process to reduce the braking torque generated by the drivetrain of the hybrid vehicle when fuel cut is prohibited. Therefore, the battery 77 is less likely to be overcharged due to regenerative power generation by the second rotating electric machine 72 during deceleration of the hybrid vehicle.

[0049] (3) The fuel cut process may be prohibited or permitted multiple times while the hybrid vehicle is traveling. If the deceleration sensation of the hybrid vehicle changes each time the driving force switching process is performed, drivability may be adversely affected. In response to this, the electronic control unit 100 maintains the reduction in braking torque through the driving force switching process until the end of the trip. This reduces the frequency of changes in the deceleration sensation while the vehicle is traveling, making it less likely that drivability will be adversely affected.

[0050] (4) The electronic control unit 100 permits the execution of motoring processing when the vehicle speed is equal to or greater than the motoring permission vehicle speed VM during deceleration of the hybrid vehicle. Furthermore, when switching driving force, the electronic control unit 100 sets a vehicle speed higher than normal as the value of the motoring permission vehicle speed VM. Therefore, even in a situation where the amount of regenerative power generated by the second rotating electric machine 72 is reduced due to a decrease in braking torque caused by the driving force switching processing, the battery 77 is less likely to be over-discharged due to the power consumption for the motoring processing.

[0051] (4) The electric power stored in the battery 77 is also supplied to parts other than the drivetrain of the hybrid vehicle. If the motoring process is performed when the electric power consumption of these parts is high, the battery 77 may be excessively discharged, resulting in over-discharge. In this embodiment, the electronic control unit 100 clears the regeneration request flag when the amount of discharge of the battery 77 is equal to or greater than the determination value X2. In other words, the electronic control unit 100 prohibits the execution of the motoring process when the amount of discharge of the battery 77 is equal to or greater than the determination value X2. This also makes it less likely that the battery 77 will be over-discharged.

[0052] (Other embodiments) This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility.

[0053] In the above embodiment, the fuel cut process is prohibited when the amount of PM accumulation exceeds a predetermined threshold. However, the fuel cut process may be prohibited under other conditions. For example, if the fuel cut process is performed when the deterioration of the three-way catalytic device 22 is advanced, the deterioration of the three-way catalytic device 22 may be accelerated. Therefore, the fuel cut process may be prohibited when the degree of deterioration of the three-way catalytic device 22 exceeds a threshold.

[0054] In the above embodiment, when the discharge amount of the battery 77 is equal to or greater than the determination value X2, the motoring process is prohibited from being performed. However, the motoring process may be permitted to be performed regardless of the discharge amount of the battery 77.

[0055] In the driving force switching process of the above embodiment, once the fuel cut process is prohibited, the braking torque is reduced until the trip ends. However, if the fuel cut process is permitted again after the reduction in braking torque, the reduction in braking torque may be canceled. In other words, the driving force switching process may be performed so that the braking torque is reduced only during the period when the fuel cut process is prohibited.

[0056] The vehicle control of the above embodiment may be applied to a hybrid vehicle having a drive train with a different configuration from that shown in FIG. (Additional notes) [Appendix 1] A device for controlling a hybrid vehicle provided with a drivetrain having an engine equipped with a filter device that captures particulate matter in the exhaust, a first rotating electric machine that generates rotational force to be applied to the engine in response to power supply from a battery, and a second rotating electric machine that generates electricity by receiving rotational force transmitted from wheels, the hybrid vehicle control device performing a fuel cut process that cuts fuel to the engine to generate engine braking while the hybrid vehicle is decelerating, a driving force switching process that makes the braking torque generated by the drivetrain while the hybrid vehicle is decelerating smaller when the fuel cut process is prohibited than when it is not prohibited, a motoring process that rotates the engine using the first rotating electric machine while the hybrid vehicle is decelerating, and combusts and purifies the particulate matter captured in the filter device, and a setting process that sets the vehicle speed at which the motoring process is permitted to be performed to a speed higher than when the fuel cut process is not prohibited when the fuel cut process is prohibited.

[0057] [Appendix 2] The control device for a hybrid vehicle according to [Appendix 1], wherein execution of the motoring process is prohibited when the discharge amount of the battery is equal to or greater than a predetermined judgment value. [Appendix 3] A control device for a hybrid vehicle as described in [Appendix 1] or [Appendix 2], which prohibits the fuel cut process from being performed when the amount of particulate matter deposited in the filter device is equal to or greater than a predetermined judgment value. [Explanation of symbols]

[0058] 10...Engine 11...cylinder 14...Crankshaft 15...Intake passage 16...Throttle valve 17...Fuel injection valve 18...Ignition device 21...Exhaust passage 22…Three-way catalyst device 23...Filter device 40...First planetary gear mechanism 41,51...Sun gear 42,52...Ring gear 43,53...Pinion gear 44...Career 45...Ring gear shaft 50...Second planetary gear mechanism 60…Reduction mechanism 61…Differential mechanism 62...Wheel 63...Drive wheels 71...1st rotating electric machine 72...2nd rotating electric machine 75...First inverter 76...Second inverter 77...Battery 100...Electronic control unit 101...Processing device 102...Storage device 103...Air flow meter 104...Crank angle sensor 105...Air-fuel ratio sensor 106...Accelerator pedal sensor 107...Shift position sensor 108...Vehicle speed sensor

Claims

1. A control device for a hybrid vehicle provided in a drivetrain having an engine equipped with a filter device that collects particulate matter in exhaust, a first rotating electric machine that generates a rotational force to be applied to the engine in response to power supplied from a battery, and a second rotating electric machine that generates electricity by receiving a rotational force transmitted from wheels, a fuel cut process for performing a fuel cut of the engine to generate engine braking while the hybrid vehicle is decelerating; a driving force switching process that reduces a braking torque generated by the drive train during deceleration of the hybrid vehicle when the fuel cut process is prohibited compared to when the fuel cut process is not prohibited; a motoring process in which the engine is rotationally driven by the first rotating electric machine during deceleration of the hybrid vehicle, and the particulate matter trapped in the filter device is combusted and purified; a setting process for setting the vehicle speed at which the motoring process is permitted to be performed, when the fuel cut process is prohibited, to a speed higher than that when the fuel cut process is not prohibited; A control device for a hybrid vehicle that performs the above.

2. 2. The control device for a hybrid vehicle according to claim 1, wherein execution of the motoring process is prohibited when the amount of discharge of the battery is equal to or greater than a predetermined judgment value.

3. 2. The control device for a hybrid vehicle according to claim 1, wherein the fuel cut process is prohibited when the amount of particulate matter deposited in the filter device is equal to or greater than a predetermined determination value.

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