Vehicle control device

Abstract

To allow a vehicle to perform retreat-travel in a first traveling mode while avoiding engine stall at a low vehicle speed even in both cases of on failure and off failure of a second engagement device.SOLUTION: In the event of a failure of a WSC clutch (second engagement device), by forcibly turning the WSC clutch into an engaged state and turning a K0 clutch (first engagement device) into the engaged state, a vehicle performs retreat-travel (S3, S4, S5, S6) in an HEV travel mode (first travel mode) using an engine as a power source, therefore a cruising range can be increased. In addition, since the WSC clutch is forcibly turned into the engaged state, the vehicle can perform the retreat-travel in the HEV travel mode not only in the case of on failure of the WSC clutch, but also in the case of off failure. On the other hand, if a vehicle speed V falls below a predetermined low-speed determination threshold Vs during the retreat-travel (determination in S4 is NO), since the K0 clutch is turned into the open state (S7), the engine is disconnected from a power transmission path and engine stall is avoided.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device, and more particularly to control when a second engagement device disposed between an electric motor and a drive wheel fails. [Background technology]

[0002] Hybrid vehicles are known that include an engine, an electric motor connected to a power transmission path between the engine and drive wheels so as to transmit power, a first engagement device that connects and disconnects the engine and the electric motor, and a second engagement device that connects and disconnects the electric motor and the drive wheels, and in which the engine and the electric motor are used as a power source for traveling. Such vehicles can be switched between a first traveling mode in which the first engagement device and the second engagement device are both engaged and the vehicle travels using at least the engine, and a second traveling mode in which the first engagement device is disengaged and the second engagement device is engaged and the vehicle travels using the electric motor. Patent Document 1 describes an example of such a vehicle. In Patent Document 1, in the event of an on-fault in which the second engagement device (CL2) remains engaged, transition to the second traveling mode (EV mode) is prohibited and evacuation traveling is performed in the first traveling mode (HEV mode), thereby extending the cruising range of the evacuation traveling. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2016 / 151657 publication Summary of the Invention [Problem to be solved by the invention]

[0004] However, because the second engagement device is maintained in an engaged state, if the first engagement device cannot be made to slip, there is a risk of the engine stalling when the vehicle speed decreases. Also, in the event of an off fault in which the second engagement device is maintained in a disengaged state, there is a risk that power transmission between the engine and electric motor (power sources) and the drive wheels will be interrupted, making it impossible to travel.

[0005] The present invention was made against the background of the above circumstances, and its purpose is to enable evacuation driving in the first driving mode while avoiding engine stall at low vehicle speeds in either the case of an on-failure or an off-failure of the second engagement device. [Means for solving the problem]

[0006] In order to achieve this object, a first invention relates to a vehicle including: (a) an engine; an electric motor connected to a power transmission path between the engine and drive wheels so as to be able to transmit power; a first engagement device that connects and disconnects the engine and the electric motor; and a second engagement device that connects and disconnects the electric motor and the drive wheels, wherein the engine and the electric motor are used as a power source for traveling; (b) a vehicle control device that can switch between a first traveling mode in which the first engagement device and the second engagement device are both in an engaged state and the vehicle travels using at least the engine; and a second traveling mode in which the first engagement device is in a disengaged state and the second engagement device is in an engaged state and the vehicle travels using the electric motor, and (c) in the event of a failure of the second engagement device, the second engagement device is forcibly brought into an engaged state and the first engagement device is brought into an engaged state and evacuation traveling is performed in the first traveling mode, while the first engagement device is brought into a disengaged state if the vehicle speed during the evacuation traveling falls below a predetermined low speed determination threshold. (d) when the vehicle speed becomes equal to or greater than the low speed determination threshold, the first engagement device is brought into an engaged state to return to the evacuation traveling mode in the first traveling mode. It is characterized by: [Effects of the Invention]

[0008] According to this vehicle control device, in the event of a failure of the second engagement device, the second engagement device is forcibly put into an engaged state and the first engagement device is also put into an engaged state, and evacuation travel is performed in the first traveling mode using the engine as a power source, thereby extending the cruising distance during evacuation travel. Furthermore, because the second engagement device is forcibly put into an engaged state, evacuation travel can be performed in the first traveling mode not only in the event of an ON failure in which the second engagement device is maintained in an engaged state, but also in the event of an OFF failure in which the second engagement device is maintained in a disengaged state. On the other hand, if the vehicle speed falls below a predetermined low speed determination threshold during evacuation travel, the first engagement device is put into a disengaged state. This allows you to drive in the second driving mode to avoid the accident. This disconnects the engine from the powertrain, preventing engine stalls. . Continue evacuation driving in 2 driving mode Meanwhile, the car speed When the speed exceeds the low speed threshold The first engagement device is again in the engaged state. Return to evacuation driving in driving mode 1 In this way, if the speed exceeds the low speed determination threshold during evacuation driving in the second driving mode, the system returns to evacuation driving in the first driving mode. This can extend the cruising range. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating a vehicle drive system equipped with a control device according to an embodiment of the present invention; [Figure 2] 2 is a hydraulic circuit diagram illustrating an example of a hydraulic control circuit for a WSC clutch provided in the vehicle of FIG. 1. FIG. [Figure 3] 2 is a flowchart specifically illustrating the operation of an evacuation travel control unit that is functionally provided in the electronic control device of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention can be applied to various hybrid vehicles that are equipped with an engine and an electric motor as power sources and that can switch between a first driving mode in which the vehicle runs using at least the engine and a second driving mode in which the vehicle runs using the electric motor. A motor generator that also functions as a generator is preferably used as the electric motor, but an electric motor that does not function as a generator can also be used. A fluid-type power transmission device such as a torque converter or an automatic transmission can be provided in the power transmission path between the electric motor and the drive wheels, as needed. If the fluid-type power transmission device is provided with a lock-up clutch (direct-coupling clutch), the lock-up clutch can also be used as the second engagement device. A gear-shift engagement device of the automatic transmission can also be used as the second engagement device.

[0011] In the event of a failure of the second engagement device, the second engagement device is forcibly placed into an engaged state. However, for example, in the event of an ON failure in which the second engagement device is maintained in an engaged state, forcible engagement control is not necessarily required; it is also possible to simply perform forcible engagement control in the event of an OFF failure in which the second engagement device is maintained in a disengaged state. When the vehicle speed falls below a predetermined low-speed determination threshold, engine stalling can be avoided by placing the first engagement device in a disengaged state, and evacuation travel can be continued, for example, in the second traveling mode. In the event that slip engagement control of the first engagement device is possible, it is also possible to perform low-speed travel, stopping, and starting while remaining in the first traveling mode by using slip engagement control of the first engagement device. [Example]

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating the schematic configuration of a drive system of a vehicle 10 equipped with an electronic control device 90 as a control device according to one embodiment of the present invention, and also illustrates key control functions and control systems for various controls in the vehicle 10. The vehicle 10 is a hybrid electric vehicle equipped with an engine 12 and an electric motor MG as power sources. The vehicle 10 includes the engine 12, drive wheels 14 (either left or right rear wheels or front wheels), and a power transmission device 18 provided in a power transmission path between the engine 12 and the drive wheels 14. The engine 12 is an internal combustion engine such as a gasoline engine or a diesel engine. The engine 12 is controlled by an electronic control device 90, which controls an engine control device 22 including a throttle actuator, a fuel injection device, an ignition device, and the like, thereby controlling the engine torque Te of the engine 12. The electric motor MG is a rotating electric machine, a so-called motor generator, that functions as both a motor that generates mechanical power from electric power and a generator that generates electric power from mechanical power. The electric motor MG is connected to a battery 28 via a PCU (Power Control Unit) 24 including an inverter, etc. The electric motor MG has the PCU 24 controlled by the electronic control device 90, whereby the MG torque Tmg, which is the torque of the electric motor MG, is controlled.

[0013] The power transmission device 18 is equipped with a K0 clutch 34, a WSC clutch 36, an automatic transmission (AT) 38, etc., within a case 32, which is a non-rotating member attached to the vehicle body, and power is transmitted from a transmission output shaft 40 to the drive wheels 14 via a differential gear 42 and a pair of drive shafts 44. The K0 clutch 34 is a first engagement device that connects and disconnects the engine 12 and the electric motor MG, and is an engine disconnection clutch that disconnects the engine 12 from the power transmission path. The WSC clutch 36 is a second engagement device that connects and disconnects the electric motor MG and the drive wheels 14, and functions as a starting clutch and an input clutch by being controlled for slip engagement by an electronic control device 90.

[0014] The power transmission device 18 is provided in the case 32 with an engine connecting shaft 46 that connects the engine 12 and the K0 clutch 34, and an electric motor connecting shaft 48 that connects the K0 clutch 34 and the WSC clutch 36. The electric motor MG is connected to the electric motor connecting shaft 48 so as to be able to transmit power. The K0 clutch 34 and the WSC clutch 36 are both wet or dry friction engagement devices formed of multi-plate or single-plate clutches pressed by actuators, and their control states, such as engaged and disengaged states, are switched by an electronic control device 90. The control state of the K0 clutch 34 is switched by changing the K0 torque Tk0, which is the torque capacity of the K0 clutch 34, using the K0 oil pressure PRk0 supplied from the hydraulic control circuit 52. The control state of the WSC clutch 36 is switched by changing the WSC torque Twsc, which is the torque capacity of the WSC clutch 36, using the WSC oil pressure PRwsc supplied from the hydraulic control circuit 52. An input side member of the WSC clutch 36 is connected to an electric motor connecting shaft 48 , and an output side member of the WSC clutch 36 is connected to a transmission input shaft 50 which is an input rotating member of the automatic transmission 38 .

[0015] The automatic transmission 38 is a known planetary gear automatic transmission equipped with, for example, multiple planetary gear devices and multiple engagement devices CB. The engagement devices CB are hydraulic friction engagement devices, such as multi-plate or single-plate clutches or brakes pressed by a hydraulic actuator, or band brakes tightened by a hydraulic actuator. Each of the engagement devices CB has its torque capacity, or CB torque Tcb, changed by the regulated CB oil pressure PRcb supplied from the hydraulic control circuit 52, thereby switching its control state, such as an engaged state or a disengaged state. The automatic transmission 38 is a stepped transmission in which one of multiple gears with different gear ratios γat (=input rotational speed Ni / output rotational speed No) is established by engaging one of the engagement devices CB. The input rotational speed Ni is the rotational speed of the transmission input shaft 50 and is the input rotational speed of the automatic transmission 38. The input rotational speed Ni is also the rotational speed of the output member of the WSC clutch 36. The output rotation speed No is the rotation speed of the transmission output shaft 40, and is the output rotation speed of the automatic transmission 38.

[0016] The vehicle 10 is equipped with a mechanical oil pump 58 and an electric oil pump 60. The mechanical oil pump 58 is connected to the electric motor connecting shaft 48 via a gear, belt, chain, or the like so as to be capable of transmitting power, and is driven by at least one of the engine 12 and the electric motor MG to discharge hydraulic oil used in the power transmission device 18. The electric oil pump 60 is rotationally driven by a pump motor (not shown) to discharge hydraulic oil. The hydraulic oil discharged by the mechanical oil pump 58 and the electric oil pump 60 is supplied to the hydraulic control circuit 52. The hydraulic control circuit 52 outputs regulated CB hydraulic pressure PRcb, K0 hydraulic pressure PRk0, WSC hydraulic pressure PRwsc, and the like based on the hydraulic oil discharged by the mechanical oil pump 58 and the electric oil pump 60, respectively.

[0017] The hydraulic control circuit 52 includes a WSC forced engagement unit 54 related to the engagement / disengagement control of the WSC clutch 36. FIG. 2 shows the hydraulic circuit of the hydraulic control circuit 52 related to the WSC clutch 36. The WSC hydraulic pressure PRwsc, which is adjusted by a linear solenoid valve SLW using line pressure PL as the source pressure, is supplied to the WSC clutch 36 to control engagement / disengagement. The line pressure PL is the source pressure for various control hydraulic pressures and is controlled, for example, in response to the accelerator pedal position θacc. The linear solenoid valve SLW is a normally open type that outputs the line pressure PL as the WSC hydraulic pressure PRwsc without modification, for example, when an excitation current is not applied. When the excitation current is not applied, the WSC clutch 36 is engaged. When an excitation current is supplied in accordance with a WSC hydraulic control command signal Swsc, the WSC hydraulic pressure PRwsc is reduced in accordance with the magnitude of the excitation current, which reduces the WSC torque Twsc accordingly. Furthermore, when the excitation current exceeds a predetermined value, the WSC clutch 36 is disengaged. An electromagnetic switching valve 56 is provided as a WSC forced engagement portion 54 in a drain oil passage 55 of the linear solenoid valve SLW.

[0018] The solenoid changeover valve 56 is normally maintained in a normal connection state shown on the right side of FIG. 2 to allow hydraulic oil to be drained from the drain oil passage 55. However, when an excitation current is supplied in accordance with a WSC forced engagement command signal Scomp output from the electronic control device 90, the solenoid changeover valve 56 is switched to a forced engagement connection state shown on the left side, and the line pressure PL is supplied to the drain oil passage 55 to forcibly engage the WSC clutch 36. In other words, even if the linear solenoid valve SLW is maintained in a closed state (drain state) due to, for example, a short circuit in the electrical circuit of the linear solenoid valve SLW, and the output of the WSC hydraulic pressure PRwsc from the linear solenoid valve SLW is stopped, the solenoid changeover valve 56 is switched to the forced engagement connection state, and the line pressure PL is supplied to the WSC clutch 36 from the solenoid changeover valve 56 via the drain oil passage 55 and the linear solenoid valve SLW, forcibly engaging the WSC clutch 36. Note that a normally closed type linear solenoid valve SLW that stops the output of the WSC hydraulic pressure PRwsc when an excitation current is not applied may also be used. Although not shown, the K0 clutch 34 is also controlled for engagement and disengagement in the same manner as the WSC clutch 36, for example, by controlling the K0 oil pressure PRk0 output from a linear solenoid valve in accordance with the K0 oil pressure control command signal Sk0.

[0019] The vehicle 10 is equipped with an electronic control device 90 as a control device that executes various types of control. The electronic control device 90 includes a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, etc., and executes various types of control of the vehicle 10. The electronic control device 90 includes multiple computers for engine control, MG control, hydraulic control, etc., as needed.

[0020] The electronic control device 90 receives signals relating to various information required for various controls from, for example, the engine rotational speed sensor 70, the input rotational speed sensor 72, the output rotational speed sensor 74, the MG rotational speed sensor 76, the accelerator pedal position sensor 80, the throttle valve position sensor 82, the brake switch 84, the battery sensor 86, the oil temperature sensor 88, and the like, such as the engine rotational speed Ne which is the rotational speed of the engine 12, the input rotational speed Ni, the output rotational speed No which corresponds to the vehicle speed V, the MG rotational speed Nmg which is the rotational speed of the electric motor MG, the accelerator pedal position θacc which indicates the amount of output required by the driver as an operation amount of the accelerator pedal or the like, the throttle valve position θth which is the opening of the electronic throttle valve, the brake ON signal Bon which is a signal indicating a state in which the brake pedal for operating the wheel brakes is being operated by the driver, the battery temperature THbat, the battery charge / discharge current Ibat, and the battery voltage Vbat of the battery 28 which is an electricity storage device, and the oil temperature THoil which is the temperature of the hydraulic oil in the hydraulic control circuit 52. The MG rotational speed Nmg is the same as the rotational speed of the input side member of the WSC clutch 36, and the input rotational speed Ni is the same as the rotational speed of the output side member of the WSC clutch 36. From these rotational speeds Nmg and Ni, the operating state of the WSC clutch 36, i.e., whether it is in a fully engaged state, a slipping engaged state, or a released state, can be determined.

[0021] The electronic control device 90 outputs an engine control command signal Se for controlling the engine 12, an MG control command signal Smg for controlling the electric motor MG, a CB hydraulic control command signal Sbc for controlling the engagement device CB, a K0 hydraulic control command signal Sk0 for controlling the K0 clutch 34, a WSC hydraulic control command signal Swsc for controlling the WSC clutch 36, a WSC forced engagement command signal Scomp for forcibly engaging the WSC clutch 36, an electric oil pump control command signal Seop, and the like to various devices provided in the vehicle 10, such as the engine control device 22, the PCU 24, the hydraulic control circuit 52, and the electric oil pump 60. The hydraulic control circuit 52 is provided with a linear solenoid valve SLW controlled by the WSC hydraulic control command signal Swsc, an electromagnetic switching valve 56 switched to a forced engagement connection state by the WSC forced engagement command signal Scomp, and various other solenoid valves that switch oil paths and control oil pressure in accordance with the K0 hydraulic control command signal Sk0 and the CB hydraulic control command signal Sbc.

[0022] The electronic control unit 90 functionally comprises a power source control unit 92, a WSC engagement control unit 94, a gear shift control unit 96, and an emergency travel control unit 98 in order to realize various controls in the vehicle 10.

[0023] The power source control unit 92 calculates the amount of driving demanded by the driver for the vehicle 10, for example, by applying the accelerator opening θacc and the vehicle speed V to a driving demand map. The driving demand map is a relationship for calculating the driving demand, which is determined experimentally or by design and stored in advance, i.e., a predetermined relationship. The driving demand may be, for example, a required driving torque Trdem [Nm], a required driving force Frdem [N], or a required driving power Prdem [W] at the drive wheels 14. The power source control unit 92 calculates a required input torque Tidem at the transmission input shaft 50 that can achieve the required driving demand, taking into account transmission loss, accessory load, the gear ratio γat of the automatic transmission 38, and the like, and then calculates a target engine torque Tetgt and a target MG torque Tmtgt that will achieve the required input torque Tidem. The power source control unit 92 then outputs an engine control command signal Se that controls the engine 12 to output the target engine torque Tetgt, and outputs an MG control command signal Smg that controls the electric motor MG to output the target MG torque Tmtgt.

[0024] For example, when the required input torque Tidem can be satisfied only with the output of the electric motor MG, the power source control unit 92 selects a BEV (Battery Electric Vehicle) driving mode, which is a motor driving mode in which the electric motor MG is driven only by power from the battery 28. In the BEV driving mode, the K0 clutch 34 is disengaged to stop the engine 12, and the WSC clutch 36 is engaged to perform BEV driving, which uses only the electric motor MG as a power source. In this BEV driving mode, the MG torque Tmg is controlled to achieve the required input torque Tidem. On the other hand, when the required input torque Tidem cannot be satisfied without using at least the output of the engine 12, the power source control unit 92 selects an HEV (Hybrid Electric Vehicle) driving mode, which is an engine driving mode. In the HEV driving mode, both the K0 clutch 34 and the WSC clutch 36 are engaged to perform engine driving, i.e., HEV driving, in which the vehicle is driven using at least the engine 12 as a power source. In this HEV driving mode, the engine torque Te is controlled to realize all or part of the required input torque Tidem, and the MG torque Tmg is controlled to compensate for the torque that is insufficient at the engine torque Te relative to the required input torque Tidem. In the HEV driving mode, for example, the engine 12 may be operated on the optimal fuel economy line, and the excess or deficiency of the engine torque Te relative to the required input torque Tidem may be compensated for by increasing or decreasing the MG torque Tmg, which is the torque of the electric motor MG. Alternatively, the engine 12 may be operated at an engine torque Te equal to or greater than the required input torque Tidem, and the surplus torque may be absorbed by regenerative control of the electric motor MG to charge the battery 28. The BEV driving mode corresponds to the second driving mode, and the HEV driving mode corresponds to the first driving mode.

[0025] The WSC engagement control unit 94 controls the WSC clutch 36 to maintain a disengaged state or a slipping engagement state when the vehicle 10 is stationary. By maintaining the WSC clutch 36 in a slipping engagement state while the vehicle is stationary, the vehicle 10 can be driven in a so-called creep mode, where the vehicle 10 creeps slowly when, for example, the accelerator pedal is released and the brake is released. Furthermore, when the vehicle 10 is driven in the BEV driving mode or the HEV driving mode, the WSC clutch 36 is controlled to maintain a fully engaged state. However, if the input rotation speed Ni falls below the operable rotation speed of the engine 12 while the vehicle is driven in the HEV driving mode at low vehicle speeds, the WSC clutch 36 is controlled to maintain a slipping engagement state.

[0026] The shift control unit 96 determines whether to shift the automatic transmission 38 using, for example, a shift map, which is a predetermined relationship, and outputs, as necessary, a CB hydraulic pressure control command signal Scb for switching the gear position of the automatic transmission 38. The shift map is a predetermined relationship having shift lines for determining whether to shift the automatic transmission 38 on a two-dimensional coordinate system using, for example, vehicle speed V and required drive torque Trdem as variables.

[0027] The evacuation travel control unit 98 performs evacuation travel to extend the cruising range when the WSC clutch 36 fails, and specifically executes signal processing in accordance with steps S1-S8 (hereinafter, the steps will be omitted and simply referred to as S1-S8) in the flowchart of Figure 3. In the flowchart of Figure 3, YES in the decision steps indicated by diamonds means affirmative, and NO means negative.

[0028] In S1 of FIG. 3, the emergency travel control unit 98 determines whether the WSC clutch 36 has failed. If not, normal travel is performed in S2. A failure of the WSC clutch 36 is typically an ON failure, in which the WSC clutch 36 remains engaged, due to a disconnection or short circuit in the electrical circuit for the linear solenoid valve SLW, or a loose connector, or an OFF failure, in which the WSC clutch 36 remains disengaged. Therefore, the emergency travel control unit 98 can determine whether the WSC clutch 36 has failed by, for example, comparing the WSC hydraulic control command signal Swsc with the operating state of the WSC clutch 36, such as the differential rotation ΔNmi (=Nmg-Ni) between the MG rotation speed Nmg and the input rotation speed Ni. During normal travel in S2, the power source control unit 92 switches between HEV and BEV driving modes based on, for example, the vehicle speed V and the required drive torque Trdem.

[0029] If it is determined in S1 that the WSC clutch 36 has failed, the evacuation travel control unit 98 executes S3 and forcibly engages the WSC clutch 36. Specifically, by outputting a WSC forced engagement command signal Scomp, the electromagnetic changeover valve 56 of the WSC forced engagement unit 54 is switched to a forced engagement connection state. As a result, in the event of an OFF failure in which the normally open linear solenoid valve SLW is closed due to a short circuit or the like in the electrical circuit, the WSC hydraulic pressure PRwsc is drained from the drain oil passage 55, and the WSC clutch 36 is maintained in an open state, the line pressure PL is supplied from the electromagnetic changeover valve 56 via the drain oil passage 55 and the linear solenoid valve SLW to the WSC clutch 36, and the WSC clutch 36 is forcibly engaged by the line pressure PL. In the event of an ON fault, in which the linear solenoid valve SLW is open due to a wire break or the like and the line pressure PL is supplied directly from the linear solenoid valve SLW to the WSC clutch 36, causing the WSC clutch 36 to be maintained in an engaged state by the line pressure PL, the WSC clutch 36 is maintained in an engaged state regardless of whether the line pressure PL is supplied from the electromagnetic switching valve 56. In other words, the WSC clutch 36 is maintained in an engaged state regardless of whether an ON fault or an OFF fault has occurred.

[0030] In the next step S4, the emergency travel control unit 98 determines whether the vehicle speed V is equal to or greater than a predetermined low-speed determination threshold Vs. If V≧Vs, the K0 clutch 34 is maintained engaged in step S5, and normal travel is performed in step S6. The low-speed determination threshold Vs is a vehicle speed at which the K0 clutch 34 would be disengaged under normal travel control, i.e., a low vehicle speed at which the engine 12 may stall. The normal travel in step S6 is emergency travel when the WSC clutch 36 fails. Since the K0 clutch 34 is maintained engaged in step S5, the vehicle is essentially traveling in HEV travel mode using the engine 12 as a power source. In this HEV travel mode, the vehicle can travel using the engine 12 as a power source while, as needed, regenerative control of the electric motor MG is performed to charge the battery 28, for example, so that the battery 28 is kept fully charged.

[0031] When the vehicle speed V decreases and becomes slower than the low-speed determination threshold Vs, resulting in a NO determination in S4, the evacuation travel control unit 98 executes S7 to disengage the K0 clutch 34 and executes S8 to perform evacuation travel in the BEV travel mode using the electric motor MG as the power source. Disengaging the K0 clutch 34 in S7 prevents the engine 12 from stalling. Stopping the engine 12 in the BEV travel mode in S8 reduces fuel consumption. When the vehicle speed V becomes equal to or greater than the low-speed determination threshold Vs during re-acceleration or starting from a stopped state, the determination in S4 becomes YES, and S5 and S6 are executed to return to evacuation travel in the HEV travel mode using the engine 12 as the power source.

[0032] As described above, the evacuation travel control unit 98 functionally provided in the electronic control device 90 of the vehicle 10 of this embodiment forcibly engages the WSC clutch 36 and engages the K0 clutch 34 in the event of a failure of the WSC clutch 36, thereby performing evacuation travel in HEV travel mode using the engine 12 as a power source (S3, S4, S5, S6), thereby extending the cruising distance during evacuation travel. Furthermore, because the WSC clutch 36 is forcibly engaged, evacuation travel can be performed in HEV travel mode not only in the event of an ON failure in which the WSC clutch 36 is maintained in an engaged state, but also in the event of an OFF failure in which the WSC clutch 36 is maintained in a released state.

[0033] On the other hand, if the vehicle speed V falls below the predetermined low-speed determination threshold Vs during evacuation travel (NO in S4), the K0 clutch 34 is opened (S7), and the engine 12 is disconnected from the power transmission path, preventing engine stall. In this case, evacuation travel can be continued in the BEV travel mode (S8), and when the vehicle speed V becomes equal to or greater than the low-speed determination threshold Vs, the system returns to evacuation travel in the HEV travel mode (S6), thereby extending the cruising range.

[0034] Although the embodiments of the present invention have been described in detail above with reference to the drawings, this is merely one embodiment, and the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0035] 10: Vehicle 12: Engine 14: Drive wheels 18: Power transmission device (power transmission path) 34: K0 clutch (first engagement device) 36: WSC clutch (second engagement device) 90: Electronic control unit (control unit) 98: Evacuation travel control unit MG: Electric motor V: Vehicle speed Vs: Low speed determination threshold

Claims

[Claim 1] A vehicle includes an engine, an electric motor connected to a power transmission path between the engine and drive wheels so as to be able to transmit power, a first engagement device that connects and disconnects the engine and the electric motor, and a second engagement device that connects and disconnects the electric motor and the drive wheels, and the engine and the electric motor are used as power sources for traveling, A vehicle control device that can switch between a first driving mode in which the first engagement device and the second engagement device are both in an engaged state and the vehicle is driven using at least the engine, and a second driving mode in which the first engagement device is in a disengaged state and the second engagement device is in an engaged state and the vehicle is driven using the electric motor, When the second engagement device fails, the second engagement device is forcibly put into an engaged state and the first engagement device is put into an engaged state, and evacuation travel is performed in the first traveling mode, while if the vehicle speed falls below a predetermined low speed determination threshold during the evacuation travel, the first engagement device is put into a disengaged state and evacuation travel is performed in the second traveling mode, and then, when the vehicle speed becomes equal to or greater than the low speed determination threshold, the first engagement device is put into an engaged state and the vehicle returns to evacuation travel in the first traveling mode. A vehicle control device characterized by:

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