Vehicle travel driving control device

Abstract

A vehicle travel drive control device 1 comprises: an engine 2 that drives travel drive wheels of a vehicle via a first power transmission path 11; a motor 4 that drives the travel drive wheels via a second power transmission path 12 different from the first power transmission path 11; an engine clutch 7a that is capable of connecting / disconnecting the first power transmission path 11; and a motor clutch 7b that is capable of connecting / disconnecting the second power transmission path 12 and switching a reduction ratio between high gear and low gear. The vehicle travel drive control device 1 controls the operations of the engine clutch 7a, the motor clutch 7b, the engine 2, and the motor 4 on the basis of parameters such as a vehicle speed. The vehicle travel drive control device 1 further comprises a hybrid control unit 30 that, when a failure of the motor clutch 7b is detected in a parallel mode, sets the engine clutch 7a to the low gear with a high reduction ratio regardless of a change in the parameters to enable the vehicle to travel by the engine 2.

Description

Travel drive control device for a vehicle

[0001] The present invention relates to a travel drive control device for a hybrid vehicle.

[0002] Conventionally, in a plug-in hybrid vehicle or a hybrid vehicle (hereinafter collectively referred to as a hybrid vehicle) equipped with an engine and an electric motor as travel drive sources, a vehicle capable of switching travel modes has been developed. Known travel modes include an EV mode in which only an electric motor drives the vehicle, a series mode in which an electric motor and an engine drive the vehicle, and a parallel mode. [[ID=,7]]

[0003] For example, the vehicle described in Patent Document 1 includes a clutch (engine clutch) in the power transmission path between the engine and the travel drive wheels. By releasing the engine clutch, a series mode is possible in which the generator is driven by the engine to generate electricity while the vehicle is driven by the motor. On the other hand, in the above-described vehicle, a parallel mode is possible in which the vehicle is driven by the engine while the driving force is assisted by the motor by engaging the engine clutch.

[0004] Further, the vehicle described in Patent Document 1 includes a clutch (motor clutch) in the power transmission path between the motor and the travel drive wheels. By releasing the motor clutch, it becomes possible to stop driving the motor while driving the vehicle by the engine.

[0005] The engine clutch and the motor clutch automatically switch based on the vehicle speed, the required driving torque of the vehicle, etc.

[0006] Also, a hybrid vehicle has been devised that employs an engine clutch configured to be able to switch the reduction ratio in the power transmission path between the engine and the travel drive wheels in multiple stages.

[0007] WO2020 / 148973 / A1

[0008] Incidentally, the importance of fail-safe mechanisms has been increasing in recent years. For example, in vehicles equipped with both a motor clutch and an engine clutch, as mentioned above, the ability to drive the vehicle in the event of a clutch malfunction or other abnormality is required. In particular, if the motor clutch becomes stuck in the disengaged position while driving in parallel mode, it may become difficult to move the vehicle to safety.

[0009] This invention has been made in view of the above problems, and its objective is to provide a vehicle drive control device that enables safe evasive driving in the event of a motor clutch failure in a hybrid vehicle equipped with a motor clutch and an engine clutch capable of switching the reduction ratio in multiple stages.

[0010] To achieve the above objective, the vehicle drive control device of the present invention includes: an engine that drives the vehicle's drive wheels via a first power transmission path; a motor that drives the drive wheels via a second power transmission path different from the first power transmission path; an engine clutch provided in the first power transmission path that can disconnect and reconnect power transmission between the engine and the drive shaft of the drive wheel, and when connected, can select a reduction ratio in the first power transmission path of at least a low gear or a high gear with a reduction ratio higher than that low gear; and a motor clutch provided in the second power transmission path that can disconnect and reconnect power transmission between the motor and the drive shaft. A vehicle driving control device having a switch and a parameter acquisition unit that acquires parameters relating to the driving state of the vehicle, and which controls the operation of the engine clutch, the motor clutch, the engine and the motor based on the parameters, is characterized in that it comprises a clutch failure detection unit that detects a failure of the motor clutch, and the driving control unit which, when a failure of the motor clutch is detected while the engine clutch is engaged with the high gear selected, executes a low gear driving process that engages the engine clutch with the low gear regardless of the parameters.

[0011] The vehicle drive control device of the present invention, when a motor clutch failure is detected while the engine clutch is engaged in high gear, executes a low-gear driving process that engages the engine clutch in low gear regardless of the parameters, thereby enabling the vehicle to travel at a low speed using the engine's driving force. This allows for safer, low-speed escape driving in the event of a motor clutch failure.

[0012] This is a diagram showing the configuration of the drive system of a vehicle equipped with a drive control device according to an embodiment of the present invention. This is a part of a flowchart showing an example of the control procedure for motor clutch failure. This is the remainder of the flowchart showing an example of the control procedure for motor clutch failure. This is a part of a flowchart showing an example of the control procedure for engine clutch failure. This is the remainder of the flowchart showing an example of the control procedure for engine clutch failure. This is an explanatory diagram showing the control content for motor clutch failure.

[0013] Embodiments of the present invention will be described below with reference to the drawings.

[0014] Figure 1 is a diagram showing the configuration of the drive system of a vehicle employing a drive control device according to one embodiment of the present invention.

[0015] The driving control device of this embodiment is applied to vehicles equipped with an engine and a motor as a driving source, such as plug-in hybrid vehicles (PHEVs) and hybrid vehicles that can be charged and supplied with external power.

[0016] As shown in Figure 1, a vehicle equipped with the driving control device 1 of this embodiment can drive by driving the drive wheels (for example, the front wheels) with the output of the engine 2, and is also equipped with an electric motor 4 that drives the drive wheels.

[0017] The engine 2 is capable of driving the drive shaft 8 of the drive wheels via the reduction gear 7, and is also capable of driving the motor generator 9 via the reduction gear 7 to generate electricity.

[0018] Motor 4 is powered by high-voltage electricity supplied from a drive battery (not shown) and a motor generator 9 mounted on the vehicle, and drives the drive shaft 8 via a reduction gear 7. In the reduction gear 7, the first power transmission path 11, which is the power transmission path between the engine 2 and the drive shaft 8, and the second power transmission path 12, which is the power transmission path between motor 4 and the drive shaft 8, are separate paths. The motor generator 9 is also powered by receiving power from the engine 2 via a third power transmission path.

[0019] The reduction gear 7 incorporates an engine clutch 7a that can switch the transmission of power in the first power transmission line 11 on and off. The reduction gear 7 also incorporates a motor clutch 7b that can switch the transmission of power between it and the second power transmission line 12 on and off.

[0020] The engine clutch 7a is driven by an electric engine clutch actuator 21 and can switch the first power transmission path 11 between connected and disconnected states. When the clutch is engaged (connected), it can also switch the reduction ratio in the first power transmission path 11 between two levels (high gear and low gear).

[0021] The motor clutch 7b is driven by an electric motor clutch actuator 22 and is capable of switching the second power transmission path 12 on and off.

[0022] The engine clutch actuator 21 and the motor clutch actuator 22 are driven and controlled by a hybrid control unit 30 (driving control unit, first determination unit, second determination unit, clutch failure detection unit) via a transmission control unit 25 mounted on the vehicle.

[0023] The power generated by the motor generator 9 is capable of charging a drive battery (not shown) mounted on the vehicle and driving the motor 4. The drive battery is equipped with a battery monitoring unit 35 that monitors the charge level (State of Charge, hereinafter referred to as SOC) and the like.

[0024] Furthermore, the vehicle is equipped with a notification unit 36 ​​that notifies the driver of a malfunction of the motor clutch 7b and the engine clutch 7a. The notification unit 36 ​​can be any device that can notify the driver, for example, through a display on the vehicle's control panel or by sound.

[0025] The hybrid control unit 30 is a control device for comprehensively controlling the vehicle and includes input / output devices, memory devices (ROM, RAM, non-volatile RAM, etc.), a central processing unit (CPU), and the like. The transmission control unit 25 is a control device for controlling the engine clutch 7a and motor clutch 7b as described above and includes input / output devices, memory devices (ROM, RAM, non-volatile RAM, etc.), a central processing unit (CPU), and the like.

[0026] The hybrid control unit 30 has the transmission control unit 25, battery monitoring unit 35, engine control unit 37 for driving and controlling engine 2, accelerator opening sensor 40 for detecting accelerator operation, and vehicle speed sensor 43 (parameter acquisition unit) for detecting vehicle speed connected to its input side. The hybrid control unit 30 receives detection information and operation information from these devices.

[0027] The hybrid control unit 30 has the transmission control unit 25, engine control unit 37, motor 4, motor generator 9, etc., connected to its output side.

[0028] The hybrid control unit 30 then calculates the vehicle's required output and driving torque necessary for driving the vehicle, based on the various detected quantities and operating information from the accelerator opening sensor 40 and other sensors. The hybrid control unit 30 also transmits control signals to the engine control unit 37, motor 4, motor generator 9, transmission control unit 25, etc. As a result, the hybrid control unit 30 switches between driving modes (EV mode: electric vehicle mode, series mode, and parallel mode), controls the output of the engine 2 and motor 4, and controls the output (generated power) of the motor generator 9.

[0029] In EV mode, the hybrid control unit 30 stops the engine 2, disengages the engine clutch 7a of the reduction gear 7, engages the motor clutch 7b, and drives the motor 4 with power supplied from the drive battery to move the vehicle.

[0030] In series mode, the hybrid control unit 30 disengages the engine clutch 7a of the reduction gear 7 and engages the motor clutch 7b, thereby operating the motor generator 9 with the engine 2. The hybrid control unit 30 then drives the motor 4 with the power generated by the motor generator 9 and the power supplied from the drive battery to move the vehicle. In series mode, the hybrid control unit 30 also sets the rotational speed of the engine 2 to a predetermined speed and supplies surplus power to the drive battery to charge it.

[0031] In parallel mode, the hybrid control unit 30 engages the engine clutch 7a of the reduction gear 7, mechanically transmitting power from the engine 2 to the drive shaft 8 via the reduction gear 7 to drive the drive wheels. The hybrid control unit 30 also drives the motor 4 using electricity generated by the motor generator 9 operated by the engine 2 and electricity supplied from the drive battery to propel the vehicle.

[0032] The hybrid control unit 30 sets the driving mode to parallel mode in areas where the engine 2 is efficient, such as high speeds. In areas other than parallel mode, i.e., in the medium to low speed range, the hybrid control unit 30 switches the vehicle's driving mode between EV mode and series mode based on the vehicle's driving torque and the state of charge (SOC) of the drive battery.

[0033] Furthermore, in parallel mode, the hybrid control unit 30 switches the engine clutch 7a to high gear or low gear based on the vehicle speed V. For example, in parallel mode, when the vehicle speed V is above a predetermined speed, the hybrid control unit 30 sets the engine clutch 7a to a high gear with a low reduction ratio. Furthermore, when the vehicle speed V is below a predetermined speed, the hybrid control unit 30 sets the engine clutch 7a to a low gear with a high reduction ratio.

[0034] Furthermore, in parallel mode, the hybrid control unit 30 releases the motor clutch 7b when the requested output becomes, for example, 0 or less. This prevents the motor 4 from being forcibly driven in conjunction with the rotation of the drive wheels when the output of the motor 4 is not needed, thereby improving the vehicle's fuel efficiency.

[0035] Furthermore, in parallel mode, when the motor clutch 7b is released, the engine clutch 7a is set to a high gear with a low reduction ratio.

[0036] The engine clutch 7a is equipped with an engine clutch stroke sensor 45 that detects the clutch stroke of the engine clutch 7a. The motor clutch 7b is equipped with a motor clutch stroke sensor 46 that detects the clutch stroke of the motor clutch 7b. The detected values ​​from the engine clutch stroke sensor 45 and the motor clutch stroke sensor 46 are input to the transmission control unit 25.

[0037] <Motor Clutch Failure Control> The hybrid control unit 30 performs motor clutch failure control to enable the vehicle to move in the event of a motor clutch failure 7b failure. Note that the motor clutch failure control may also be performed by the transmission control unit 25.

[0038] Figures 2 and 3 are flowcharts showing an example of a control procedure for motor clutch failure control.

[0039] The control shown in Figures 2 and 3 is repeatedly executed at predetermined intervals (e.g., several msec) while the vehicle is in motion (for example, when the vehicle speed V is greater than 0 km / h).

[0040] First, the hybrid control unit 30 determines whether the value of the failsafe flag F1 is 1 (step S10). In this step, the value of the failsafe flag F1 is set to 0 when the vehicle power is turned on or after a clutch failure is repaired at a repair shop, etc., and is set to 1 in step S30, which will be described later, when a motor clutch fails.

[0041] Next, the hybrid control unit 30 determines whether or not the motor clutch 7b is malfunctioning (step S20). Specifically, the hybrid control unit 30 compares the operation control signal of the motor clutch actuator 22 with the detected value of the motor clutch stroke sensor 46 to determine whether or not the motor clutch 7b is malfunctioning.

[0042] If the hybrid control unit 30 determines that the motor clutch 7b is malfunctioning, it sets the value of the failsafe flag F1 related to the motor clutch 7b to 1 (step S30).

[0043] Next, the hybrid control unit 30 controls the notification unit 36 ​​to start notifying the driver that the motor clutch 7b has malfunctioned (step S40).

[0044] Then, the hybrid control unit 30 determines whether the motor clutch 7b is in the released state based on the detection value of the motor clutch stroke sensor 46 (step S50).

[0045] When the hybrid control unit 30 determines that the motor clutch 7b is in the released state, it acquires the current driving mode set based on the vehicle speed, required output, etc. (step S60).

[0046] Next, as shown in FIG. 3, the hybrid control unit 30 determines whether the driving mode acquired in step S60 is the parallel mode and whether the engine clutch 7a is in the high gear (step S75).

[0047] When the hybrid control unit 30 determines that the driving mode is the parallel mode and the engine clutch 7a is in the high gear, it acquires the current vehicle speed V from the vehicle speed sensor 43 (step S80).

[0048] Subsequently, the hybrid control unit 30 determines whether the vehicle speed V is less than the minimum speed at which the vehicle can travel in the parallel mode (parallel minimum speed Vp). The parallel minimum speed Vp is the vehicle speed corresponding to the lower limit rotational speed of the engine 2 in the parallel mode.

[0049] When the hybrid control unit 30 determines that the vehicle speed V is less than the parallel minimum speed Vp, it controls the engine clutch actuator 21 to release the engine clutch 7a in the high gear and terminate the parallel mode (step S100). As a result, the driving mode of the vehicle shifts to the series mode or the EV mode based on the vehicle speed, required output, etc. as described above.

[0050] When the hybrid control unit 30 determines in step S75 that the driving mode of the vehicle is not the parallel mode, it determines whether the engine clutch 7a is in the low gear based on the detection value of the engine clutch stroke sensor 45 (step S135).

[0051] When the hybrid control unit 30 determines that the engine clutch 7a is in low gear, it drives the motor generator 9 to drive the vehicle (step S136).

[0052] On the other hand, if the hybrid control unit 30 determines that the engine clutch 7a is not in low gear (determines that the engine clutch 7a is in high gear), it engages the engine clutch 7a in low gear (step S137).

[0053] Furthermore, after the hybrid control unit 30 determines in step S50 that the motor clutch 7b is not in the disengaged state (i.e., it is in the engaged state), it prevents the motor clutch 7b from disengaging, as shown in Figure 2, and maintains the engaged state (step S140).

[0054] Furthermore, after determining in step S20 that the motor clutch 7b is not malfunctioning, the hybrid control unit 30 updates the driving mode (step S150). That is, the vehicle's driving mode is updated to a driving mode set based on the vehicle speed V, the requested output, etc.

[0055] The hybrid control unit 30 returns to this process if it determines in step S90 that the vehicle speed V is equal to or greater than the parallel minimum speed Vp, or if it has executed any of the processes in steps S100, S136, S137, S140, and S150.

[0056] The hybrid control unit 30 performs motor clutch failure control as shown in Figures 2 and 3. If it determines that the motor clutch 7b has failed while the vehicle is running (YES in step S20), it sets the value of the failsafe flag F1 to 1 (step S30) and notifies the driver that the motor clutch 7b has failed (step S40).

[0057] Furthermore, the hybrid control unit 30 determines that the motor clutch 7b is faulty (YES in step S20), and if it determines that the motor clutch 7b is not in an open state (is in a connected state) (NO in step S50), it prohibits the opening of the motor clutch 7b (step S140), thereby restricting the switching of the driving mode.

[0058] Furthermore, in the event of a motor clutch 7b failure (YES in step S20), if the motor clutch 7b is in an open state (YES in step S50) and the engine clutch 7a is in parallel mode in low gear (NO in step S75 and YES in step S135), the hybrid control unit 30 enables driving by the motor generator 9 (step S136).

[0059] Then, in the event of a motor clutch 7b failure (YES in step S20), if the motor clutch 7b is in an open state (YES in step S50) and the driving mode is series mode or EV mode (NO in steps S75 and S135), the hybrid control unit 30 engages the engine clutch 7a in low gear.

[0060] Furthermore, in the event of a motor clutch 7b failure (YES in step S20), if the motor clutch 7b is in an open state (YES in step S50) and the engine clutch 7a is in high-gear parallel mode (YES in step S75), the hybrid control unit 30 reduces the vehicle speed V to the minimum parallel speed Vp (YES in step S90) and then releases the engine clutch 7a (step S100). This allows the vehicle to travel at a low speed using the engine 2 until the vehicle speed V drops to the minimum parallel speed Vp in the event of a motor clutch 7b failure.

[0061] Furthermore, if the fail-safe flag F1 is set to 1 due to a motor clutch 7b failure, it will remain at 1 until the vehicle power is switched from OFF to ON, or until it is set to 0 at a repair shop or similar location. This ensures that once a motor clutch 7b failure is detected, further failure detection of the motor clutch 7b is unnecessary, at least until the vehicle comes to a stop.

[0062] <Engine Clutch Failure Control> The hybrid control unit 30 also performs engine clutch failure control, which controls the vehicle to enable retraction driving in the event of a failure of the engine clutch 7a. Note that the engine clutch failure control may also be performed by the transmission control unit 25.

[0063] Figures 4 and 5 are flowcharts showing an example of a control procedure for engine clutch failure control.

[0064] The engine clutch failure control is repeatedly executed at predetermined intervals (e.g., several msec) while the vehicle is in motion (e.g., when the vehicle speed V is greater than the speed [0 km / h]).

[0065] First, the hybrid control unit 30 determines whether the value of the fail-safe flag F2 is 1 (step S210). In this step, the value of the fail-safe flag F2 is set to 0 when the vehicle power is turned on or after a clutch failure is repaired at a repair shop, etc., and is set to 1 in step S230, which will be described later, when an engine clutch failure occurs.

[0066] When the hybrid control unit 30 determines that the value of the failsafe flag F2 is 1, it determines whether or not the engine clutch 7a is malfunctioning (step S220). Specifically, the hybrid control unit 30 compares the operation control signal of the engine clutch actuator 21 with the detected value of the engine clutch stroke sensor 45 to determine whether or not the engine clutch 7a is malfunctioning.

[0067] If the hybrid control unit 30 determines that the engine clutch 7a is malfunctioning, it sets the value of the fail-safe flag F2 related to the engine clutch 7a to 1 (step S230).

[0068] Next, the hybrid control unit 30 controls the notification unit 36 ​​to start notifying the driver that the engine clutch 7a is malfunctioning (step S240).

[0069] Next, the hybrid control unit 30 acquires the current driving mode, which is set based on the vehicle speed V and the requested output, and determines whether or not the driving mode is parallel mode (step S250).

[0070] When the hybrid control unit 30 determines that the driving mode is parallel mode, it controls the engine clutch actuator 21 to release the engine clutch 7a and end the parallel mode (step S260).

[0071] Then, the hybrid control unit 30 updates the driving mode (step S270). That is, the vehicle's driving mode is updated from parallel mode to series mode or EV mode.

[0072] If the hybrid control unit 30 determines in step S250 that the vehicle's driving mode is not parallel mode, it determines whether or not the engine clutch 7a is in an open state based on the value detected by the engine clutch stroke sensor 45 (step S280).

[0073] When the hybrid control unit 30 determines that the engine clutch 7a is not in the disengaged state, it determines that the engine clutch 7a is stuck and, as shown in Figure 5, terminates the series mode and commands the engine control unit 37 to make the engine torque Te equal to the friction torque Tf (in this embodiment, torque 0 [Nm] or less) (step S290).

[0074] Next, the hybrid control unit 30 obtains the engine torque Te from the engine control unit 37 (step S300).

[0075] Next, the hybrid control unit 30 obtains the current vehicle speed V from the vehicle speed sensor 43 (step S310).

[0076] The hybrid control unit 30 then determines whether the engine torque Te is less than or equal to the lower limit torque (in this embodiment, torque 0 [Nm]) (step S320).

[0077] When the hybrid control unit 30 determines that the engine torque Te is below the lower limit torque, it determines whether the vehicle speed V is below the motor drive upper limit speed Vf (in this embodiment, whether the speed is 20 [km / h] or less) (step S330).

[0078] When the hybrid control unit 30 determines that the vehicle speed V is less than or equal to the motor drive upper limit speed, it performs driving using the motor 4, with a maximum speed of 20 [km / h] (step S340).

[0079] If the hybrid control unit 30 determines in step S320 that the engine torque Te is greater than the lower limit torque, it controls the amount of power generated by the motor generator 9 to offset the engine torque Te (step S350). The hybrid control unit 30 controls the deceleration of the rotational speed of the engine 2 by controlling the motor generator 9 in this way. If the hybrid control unit 30 determines in step S330 that the vehicle speed V is greater than the motor drive upper limit speed Vf, or if it performs the process in S350, it controls the motor torque to torque 0 [Nm] to decelerate the vehicle (step S360).

[0080] If the hybrid control unit 30 determines in step S280 that the engine clutch 7a is not in the disengaged state (i.e., it is in the engaged state), it prohibits the parallel mode (step S370). In other words, even if the conditions for selecting the parallel mode are met due to changes in vehicle speed V or requested output, the vehicle's driving mode will not switch to the parallel mode, but will maintain the series mode or EV mode.

[0081] After determining in step S220 that the engine clutch 7a is not malfunctioning, the hybrid control unit 30 updates the driving mode (step S380). That is, the vehicle's driving mode is updated to a driving mode set based on the vehicle speed V, requested output, etc.

[0082] Then, the hybrid control unit 30 performs the processing in step S270, or the processing in step S340, or one of the processing in steps S360, S370, and S380, and then returns to this routine.

[0083] The hybrid control unit 30, by executing the engine clutch failure control shown in Figures 4 and 5, determines that the engine clutch 7a has failed while the vehicle is in motion (YES in step S220), sets the value of the failsafe flag F2 to 1 (step S230), and notifies the driver that the engine clutch 7a has failed (step S240).

[0084] Furthermore, the hybrid control unit 30 determines that the engine clutch 7a is faulty (step S220), and if the vehicle's driving mode is parallel mode (YES in step S250), it terminates the parallel mode (step S260).

[0085] Furthermore, if the hybrid control unit 30 determines that the engine clutch 7a is faulty (YES in step S220), and that the driving mode is series mode or EV mode (NO in step S250), and that the engine clutch 7a is disengaged (YES in step S280), it prohibits parallel mode (step S370).

[0086] Then, the hybrid control unit 30 determines that the engine clutch 7a is faulty (YES in step S220), that the driving mode is series mode or EV mode (NO in step S250), and that the engine clutch 7a is disengaged (YES in step S280), and prohibits parallel mode (step S370). As a result, the vehicle's driving mode is maintained in series mode or EV mode.

[0087] Furthermore, if the hybrid control unit 30 determines that the engine clutch 7a is faulty (YES in step S220), that the driving mode is series mode or EV mode (NO in step S250), and that the engine clutch 7a is not disengaged (NO in step S280), it terminates the series mode and reduces the engine torque Te to friction torque Tf (step S290).

[0088] Furthermore, if the engine torque Te exceeds 0 [Nm] (NO in step S320), the hybrid control unit 30 uses the motor generator 9 to counteract the engine torque Te (step S350), quickly setting the motor torque Tm to 0 [Nm] to decelerate the vehicle (step S360).

[0089] Furthermore, the hybrid control unit 30, after the engine torque Te has become 0 [Nm] or less (YES in step S320), and the vehicle speed V is less than or equal to the maximum vehicle speed Vf in case of failure (YES in step S330), executes a motor driving continuation process that uses the maximum vehicle speed Vf in case of failure as the upper limit for motor driving (step S340). By controlling the amount of power generated to offset the engine torque Te (step S350), the motor torque Tm is quickly set to 0 [Nm] to decelerate the vehicle (step S360).

[0090] Furthermore, the hybrid control unit 30 also decelerates the vehicle by setting the motor torque Tm to 0 [Nm] if the engine torque Te is 0 [Nm] or less (YES in step S320) and the vehicle speed V exceeds the upper limit vehicle speed Vf in case of failure (NO in step S330) (step S360).

[0091] Furthermore, if the fail-safe flag F2 is set to 1 due to a motor clutch 7b failure, it will remain at 1 until the vehicle power is switched from OFF to ON, or until it is set to 0 at a repair shop or similar location. This ensures that once a failure of the engine clutch 7a is detected, further failure detection of the engine clutch 7a is unnecessary, at least until the vehicle comes to a stop.

[0092] <Operation of Motor Clutch Failure Control> Figure 6 is an explanatory diagram showing the control content of motor clutch failure control, and shows the driving control content when the motor clutch 7b is functioning normally and when it fails during parallel driving.

[0093] As shown in Figure 6, for example, when the motor clutch 7b is in an open state, such as during deceleration in parallel mode, if the motor clutch 7b is functioning normally, the motor clutch 7b will engage in response to a decrease in vehicle speed or a change in the requested output. Furthermore, the vehicle's driving mode changes to series mode or EV mode when the engine clutch 7a is released based on a decrease in vehicle speed V or a change in the requested output, i.e., a change in parameters related to the driving state.

[0094] In parallel mode, if the motor clutch 7b is disengaged and it is determined that the motor clutch 7b is malfunctioning, the parallel mode is maintained with the engine clutch 7a engaged, keeping the motor clutch 7b disengaged regardless of changes in parameters related to the driving state, until the vehicle speed V reaches the minimum parallel speed Vp. Then, when the vehicle speed V reaches the minimum parallel speed Vp, the low-gear driving process is initiated, switching the engine clutch 7a from high gear to low gear.

[0095] Furthermore, even after the vehicle has stopped during emergency maneuvers, the low-gear driving process allows the vehicle to start again at a low speed using motor 4.

[0096] As described above, in this embodiment, if a malfunction of the motor clutch 7b is detected by the hybrid control unit 30 during driving, the motor clutch 7b will not be released if it is in the engaged state. That is, if the hybrid control unit 30 is determined to be in parallel mode, where the engine clutch 7a is engaged, based on parameters such as the vehicle's driving speed, and a malfunction of the motor clutch 7b is detected, the unit will maintain the engagement of the engine clutch 7a regardless of subsequent changes in the parameters. This makes it possible to continue driving by outputting the driving force of the engine 2 to the drive shaft 8.

[0097] Furthermore, if the hybrid control unit 30 detects a malfunction in the motor clutch 7b and the engine clutch 7a is set to a high gear with a low reduction ratio, it initiates a low gear driving process to set it to a low gear with a higher reduction ratio. This makes it easier to slow down the vehicle and perform evasive maneuvers.

[0098] Furthermore, if the hybrid control unit 30 detects a malfunction in the motor clutch 7b while it is disengaged, and the engine clutch 7a is in high gear, it switches the engine clutch 7a from high gear to low gear when the vehicle speed falls below the parallel minimum speed Vp. This suppresses vibrations and other issues during the switching process, thereby reducing discomfort for the driver and other occupants of the vehicle.

[0099] Furthermore, as described above, the hybrid control unit 30 prohibits the disengagement of the motor clutch 7b when it detects that the motor clutch 7b has failed while engaged. This allows the vehicle to coast, then move away using the motor 4, and then come to a complete stop.

[0100] The hybrid control unit 30 may prohibit vehicle acceleration if a malfunction of the motor clutch 7b is detected.

[0101] This prevents a vehicle with a faulty motor clutch 7b from reaching high speeds, thereby improving safety in the event of a motor clutch failure.

[0102] Furthermore, in the event of a motor clutch 7b failure, if the vehicle is in parallel mode and the reduction ratio is set to low gear, the drive control device 1 controls the operation of the motor generator 9 so that the output torque of the motor generator 9 is transmitted to the drive shaft 8. By transmitting the output of the motor generator 9 from the low gear with a high reduction ratio to the drive shaft 8, it is possible to drive at low vehicle speeds, making it easier for the vehicle driver to take evasive action.

[0103] Furthermore, when the motor clutch 7b fails, the hybrid control unit 30 performs low-gear driving as described above, and after the vehicle has stopped after performing a retreat run, if, for example, an acceleration command is issued by operating the accelerator, it controls the operation of the motor generator 9 so that the output torque of the motor generator 9 is transmitted to the drive shaft 8. As a result, even after the vehicle has temporarily stopped during a retreat run in the event of a motor clutch 7b failure, the vehicle can be driven again, improving the retreat performance, such as adjusting the vehicle's stopping position.

[0104] Furthermore, when a malfunction of the motor clutch 7b is detected, the hybrid control unit 30 notifies the driver of the malfunction via the notification unit 36, allowing the driver to easily recognize the malfunction of the motor clutch 7b and prompting them to take evasive action.

[0105] This concludes the description of the embodiments, but the embodiments of the present invention are not limited to those described above. For example, in the vehicle of the above embodiment, the engine clutch can switch the reduction ratio between two stages, high gear and low gear, but the reduction ratio may be switchable between three or more stages.

[0106] Furthermore, the present invention can be applied to front-wheel drive vehicles, rear-wheel drive vehicles, and four-wheel drive vehicles.

[0107] 1. Driving control device 2. Engine 4. Motor 7b. Motor clutch 7a. Engine clutch 8. Drive shaft 9. Motor generator 11. First power transmission path 12. Second power transmission path 13. Third power transmission path 30. Hybrid control unit (driving control unit, first determination unit, second determination unit, clutch failure detection unit) 36. Notification unit 43. Vehicle speed sensor (parameter acquisition unit)

Claims

1. A vehicle driving control device comprising: an engine that drives the vehicle's drive wheels via a first power transmission path; a motor that drives the vehicle's drive wheels via a second power transmission path different from the first power transmission path; an engine clutch provided in the first power transmission path that can disconnect and reconnect power transmission between the engine and the drive shaft of the vehicle's drive wheels, and when connected, can select a reduction ratio in the first power transmission path of at least low gear or a high gear with a reduction ratio higher than said low gear; a motor clutch provided in the second power transmission path that can disconnect and reconnect power transmission between the motor and the drive shaft; and a parameter acquisition unit that acquires parameters relating to the vehicle's driving state, wherein the vehicle driving control device controls the operation of the engine clutch, the motor clutch, the engine and the motor based on the parameters, comprising: a clutch failure detection unit that detects a failure in the motor clutch; and a driving control unit that, when a failure in the motor clutch is detected while the engine clutch is engaged with a high gear selected, executes a low gear driving process to engage the engine clutch with the low gear regardless of the parameters.

2. The driving control device according to claim 1, characterized in that the parameter acquisition unit acquires the driving speed of the vehicle as the parameter, and the driving control unit starts the low-gear driving process when the driving speed falls below a predetermined lower limit speed.

3. A driving control device according to claim 1 or 2, comprising a first determination unit for determining whether or not the motor clutch is engaged, wherein the driving control unit prohibits the disengagement of the motor clutch if a malfunction of the motor clutch is detected while the motor clutch is engaged.

4. The driving control device according to claim 1 or 2, characterized in that the driving control unit prohibits acceleration of the vehicle when a malfunction of the motor clutch is detected.

5. A driving control device according to claim 1 or 2, applicable to a vehicle having a battery, a motor generator, and a third power transmission path for transmitting power between the motor generator, the drive shaft, and the engine, wherein the driving control device comprises a second determination unit that determines whether the reduction ratio is set to the low gear or the high gear by the engine clutch, and the driving control unit controls the operation of the motor generator so that the output torque of the motor generator is transmitted to the drive shaft when the reduction ratio is set to the low gear.

6. The driving control device according to claim 5, characterized in that the driving control unit controls the operation of the motor generator so that the output torque of the motor generator is transmitted to the drive shaft when the vehicle restarts after stopping.

7. A driving control device according to claim 1 or 2, comprising a notification unit that notifies the engine clutch of a malfunction when the clutch malfunction detection unit detects a malfunction of the engine clutch.

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