Control device for a vehicle

Abstract

This invention provides a vehicle control device capable of implementing appropriate fail-safe handling for the clutch, taking into account the vehicle's fault location. When an abnormality occurs, the control device performs fail-safe control as follows: setting the clutch to any of the following three states: a released fixed state (keeping the clutch in a released state), an engaged fixed state (keeping the clutch in an engaged state), and a switching prohibition state (keeping the clutch in its current state). In the event of a fault preventing the clutch from being engaged, the clutch is set to a released fixed state. In the event of an actuator failure, the clutch is set to a switching prohibition state. In the event of a fault preventing the clutch from being released and a power source (first electric motor) failure, the clutch is set to an engaged fixed state.

Description

Technical Field

[0001] The present invention relates to a control device for a vehicle, the vehicle comprising: a power source that drives a main drive wheel; an electric motor that drives an auxiliary drive wheel; and a clutch disposed on the power transmission path between the auxiliary drive wheel and the electric motor. Background Technology

[0002] A vehicle control device is known, comprising: a power source driving a main drive wheel; an electric motor driving an auxiliary drive wheel; and a clutch disposed on the power transmission path between the auxiliary drive wheel and the electric motor. For example, the drive control device described in Patent Document 1 is such a device. Patent Document 1 discloses a technique for determining clutch malfunctions by using the rotational speed of the electric motor and the rotational speed of the auxiliary drive wheel when engaging or disengaging the clutch.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2018-149968 Summary of the Invention

[0004] In the aforementioned vehicle, in the event of an abnormality (e.g., malfunction) in the clutch and the actuator that switches the clutch, conventionally, as a fail-safe control for the clutch, the following controls were implemented: if the clutch cannot be engaged, the clutch is kept in a released state and remains in a released state; if the clutch cannot be released, the clutch is kept engaged and remains in an engaged state; or clutch switching is prohibited and the current state is maintained. However, conventional fail-safe controls do not consider malfunctions other than those involving the clutch and actuator, leaving room for improvement. For example, in the aforementioned vehicle, if the power source malfunctions in all-wheel drive (4WD) mode with the clutch engaged, and the driver switches to two-wheel drive (2WD) mode with only the main drive wheels in this state, the clutch may be switched to a released state since the clutch and actuator are functioning normally, potentially leading to the vehicle becoming immobile. That is, even with malfunctions other than those involving the clutch and actuator, depending on the location of the malfunction, if appropriate fail-safe measures are not implemented for the clutch, the vehicle may stop on the road, affecting driver safety.

[0005] The present invention was made against the background described above, and its purpose is to provide a vehicle control device capable of performing appropriate fail-safe handling of the clutch in consideration of the vehicle's faulty parts.

[0006] The subject of the first invention is a control device for a vehicle, (a) the vehicle comprising: a power source driving a main drive wheel; an electric motor driving an auxiliary drive wheel; a battery transmitting and receiving power between the battery and the electric motor; a clutch disposed on the power transmission path between the auxiliary drive wheel and the electric motor; and an actuator for switching the clutch in a released state and an engaged state, (b) in the event of an abnormality, the control device performs the following fail-safe control: a released fixed state in which the clutch is in a released state and remains in a released state; an engaged fixed state in which the clutch is in an engaged state and remains in an engaged state; and a switching prohibition state in which the clutch remains in its current state, (c) in the event of a fault that prevents the clutch from being set to the engaged state, the clutch is set to the released fixed state; in the event of a fault that prevents the clutch from being set to the released state and a fault that prevents the power source from being set to the engaged fixed state, the clutch is set to the engaged fixed state.

[0007] Invention Effects

[0008] According to the first invention, when the control device malfunctions, the following fail-safe controls are performed: a released fixed state (keeping the clutch in a released state), an engaged fixed state (keeping the clutch in an engaged state), and a switching prohibition state (keeping the clutch in its current state). If the malfunction is a fault preventing the clutch from being engaged, the clutch is set to the released fixed state. If the actuator malfunctions, the clutch is set to the switching prohibition state. In the event of both a fault preventing the clutch from being released and a power source malfunction, the clutch is set to the engaged fixed state. Thus, in the event of a power source malfunction, the clutch is set to the engaged fixed state, thereby enabling appropriate fail-safe control of the clutch that takes into account the faulty parts of the vehicle, such as by appropriately implementing avoidance maneuvers. Attached Figure Description

[0009] Figure 1 This is a diagram illustrating the general configuration of a vehicle to which the present invention is applied.

[0010] Figure 2 This is a flowchart illustrating the main control actions of the electronic control device, and a flowchart illustrating an example of the fail-safe control action of the clutch performed by the electronic control device when an abnormality occurs.

[0011] Figure 3 This is a flowchart illustrating the control actions of an existing example of an electronic control device. Detailed Implementation

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0013] Example

[0014] Figure 1 This is a diagram illustrating the schematic configuration of the vehicle 10 to which the present invention is applied. Figure 1 In this vehicle 10, the left and right front wheels 12, the front drive unit 20 driving the front wheels 12, the left and right rear wheels 14, and the rear drive unit 30 driving the rear wheels 14 are all separately provided. Furthermore, the vehicle 10 includes: a battery 40, which serves as a DC power source capable of charging and discharging; and an on-board charger 42, which charges the battery 40 from an external power source. Additionally, the term "left and right" refers to left and right relative to the direction of travel of the vehicle 10.

[0015] Vehicle 10 is an all-wheel drive vehicle capable of adjusting the drive torque distribution between the front wheels 12 and the rear wheels 14. All-wheel drive (AWD) has the same meaning as four-wheel drive (4WD). In addition to driving in 4WD mode, vehicle 10 can also drive in two-wheel drive (2WD) mode, distributing drive torque only to the rear wheels 14. The rear wheels 14 are equivalent to the "main drive wheels" of this invention, and the front wheels 12 are equivalent to the "auxiliary drive wheels" of this invention.

[0016] The front drive unit 20 includes a second electric motor MG2 and a front power control unit (PCU) 24. The second electric motor MG2 is a known rotating electromechanical device, a so-called motor generator, and is connected to the battery 40 via the front PCU 24. The second electric motor MG2 is an electric motor that drives the front wheel 12, which serves as an auxiliary drive wheel. The front PCU 24 is a motor control device that controls the power exchanged between the battery 40 and the second electric motor MG2 and controls the operation of the second electric motor MG2. It controls the power of the second electric motor MG2 through the electronic control unit 80 described later.

[0017] The front drive unit 20 includes a reversing gear mechanism 50, a reversing shaft 52, a final gear 54, and a front differential gear (hereinafter referred to as the front differential) 56. Furthermore, the front drive unit 20 includes left and right front drive shafts 58 connected to the front differential 56. The reversing gear mechanism 50 is a gear pair having a drive gear 50a and a driven gear 50b meshing with the drive gear 50a. The drive gear 50a is connected to the second electric motor MG2, and the driven gear 50b is connected to the final gear 54 via the reversing shaft 52. The final gear 54 meshes with the differential ring gear 56r of the front differential 56. The front drive shafts 58 connect the front differential 56 and the front wheels 12. The front drive unit 20 transmits power from the second electric motor MG2 to the front wheels 12.

[0018] The front drive unit 20 includes a clutch mechanism 60. The clutch mechanism 60 includes a claw clutch 62 and an actuator 64. The claw clutch 62 is a known engaging clutch located on the power transmission path between the front wheel 12 and the second electric motor MG2. The actuator 64 is, for example, an electrically driven or hydraulically driven actuator, which switches the engagement and disengagement states of the claw clutch 62 under control from an electronic control unit 80 described later. The claw clutch 62 corresponds to the "clutch" of this invention.

[0019] A claw clutch 62 is provided, for example, in the power transmission path between the front differential 56 and the left front wheel 12. The claw clutch 62 has a first tooth 62a and a second tooth 62b as opposing meshing teeth. The first tooth 62a is connected to the front differential 56 and is the meshing tooth on the side of the second electric motor MG2. The second tooth 62b is connected to the left front drive shaft 58 and is the meshing tooth on the side of the front wheel 12. The claw clutch 62 is engaged by the first tooth 62a and the second tooth 62b, and is released by disengaging them.

[0020] The rear drive unit 30 includes a first electric motor MG1 and a rear PCU 34. The first electric motor MG1 is a known rotating electromechanical device, a so-called motor-generator, and is connected to the battery 40 via the rear PCU 34. The first electric motor MG1 is the power source for driving the rear wheel 14, which serves as the main drive wheel. The rear PCU 34 has the same function as the front PCU 24 and controls the power of the first electric motor MG1 through the electronic control unit 80 described later.

[0021] The rear drive unit 30 includes a reversing gear mechanism 70, a reversing shaft 72, a final gear 74, a rear differential gear 76, and left and right rear drive shafts 78. The rear drive unit 30 has the same function as the front drive unit 20, transmitting power from the first electric motor MG1 to the rear wheels 14.

[0022] In vehicle 10, the rear wheel 14 is driven in both 2WD and 4WD states, while the front wheel 12 is driven only in 4WD state. In 4WD state, the front wheel 12 and rear wheel 14 are driven with the claw clutch 62 engaged, and the power transmission path between the front wheel 12 and the second electric motor MG2 is connected. In 2WD state, the rear wheel 14 is driven only with the claw clutch 62 disengaged, and the power transmission path between the front wheel 12 and the second electric motor MG2 is disconnected. Being disconnected in 2WD state stops the rotation of the rotating components of the front drive unit 20 or the second electric motor MG2, which are closer to the second electric motor MG2 than the claw clutch 62. This prevents or suppresses power loss caused by the rotation of the reverse gear mechanism 50, the final gear 54, the front differential 56, etc. The claw clutch 62 is a disconnecting mechanism capable of cutting off the power transmission path between the front wheel 12 and the second electric motor MG2.

[0023] The vehicle 10 also includes an electronic control unit 80 as its control device. The electronic control unit 80 includes an integrated electronic control unit (ECU) 82 and a clutch ECU 84. The integrated ECU 82 controls systems related to the driving of the vehicle 10, including the front PCU 24 (second electric motor MG2), the rear PCU 34 (first electric motor MG1), and the battery 40. The clutch control ECU 84 controls the actuator 64 based on command signals from the integrated ECU 82 to switch the engagement and disengagement states of the claw clutch 62. The integrated ECU 82 and the clutch ECU 84 constitute a controller comprising a so-called microcomputer.

[0024] The integrated ECU 82 is supplied with various signals based on the detection values ​​of various devices and sensors present in the vehicle 10. These devices and sensors include, for example, the front PCU 24, the rear PCU 34, the on-board charger 42, the clutch ECU 84, the throttle opening sensor 90, the brake sensor 92, the driving status setting switch 94, the battery charge remaining sensor 96, the acceleration sensor 98, the yaw acceleration sensor 100, the wheel speed sensor 102, and the on-board camera 104. Various signals include, for example, MG2 operating information Img2 including the rotational speed Nmg2, drive current Amg2, and internal temperature Tmg2 of the second motor MG2; MG1 operating information Img1 including the rotational speed Nmg1, drive current Amg1, and internal temperature Tmg1 of the first motor MG1; charger operating information Ibc indicating the operating status of the on-board charger 42; clutch operating information Ic including the travel position Ldg of the claw clutch 62 or the drive current Adg (or drive oil pressure Pdg) of the actuator 64; throttle opening θacc; brake operation amount Bra; driving status setting signal Dmd; battery charge remaining amount SOC of the battery 40; lateral acceleration Gy of the vehicle 10; yaw acceleration Ryaw, which is the rotational angular velocity of the vehicle 10 about the vertical axis; left front wheel speed Nwfl; right front wheel speed Nwfr; left rear wheel speed Nwrl; right rear wheel speed Nwrr; and on-board camera image information Iard. The driving state setting switch 94 is a switch for the driver to select whether to drive in 2WD or 4WD mode, and supplies a driving state setting signal Dmd corresponding to the selected driving state. Lateral acceleration Gy and yaw acceleration Ry aw represent the left-right acceleration and turning acceleration generated in the vehicle 10, respectively.

[0025] The integrated ECU 82 outputs various command signals to the various devices in the vehicle 10. These devices include, for example, the front PCU 24, the rear PCU 34, the on-board charger 42, and the clutch ECU 84. The various command signals include, for example, the MG2 control signal Smg2 for controlling the second electric motor MG2, the MG1 control signal Smg1 for controlling the first electric motor MG1, the charger control signal Sbc for controlling the on-board charger 42, and the clutch control signal Sc for controlling the switching between the engagement and disengagement states of the claw clutch 62.

[0026] The integrated ECU 82 calculates the requested acceleration or deceleration of the vehicle 10 based on the throttle opening θacc and / or braking operation amount Bra, and switches the drive state based on the requested acceleration or deceleration, wheel slip, driver driving state setting, etc. For example, in 2WD state, when the driver selects 4WD state through the operation of the driving state setting switch 94, the integrated ECU 82 controls the front PCU 24 (second motor MG2) to synchronize the first dog tooth 62a's first dog rotation speed Ndg1 calculated based on the second motor MG2's rotation speed Nmg2 with the second dog tooth 62b's second dog rotation speed Ndg2, which is equivalent to the left front wheel rotation speed Nwfl. Then, it outputs a clutch control signal Sc to the clutch ECU 84 to engage the claw clutch 62. Then, the clutch ECU 84 controls the actuator 64 to switch the claw clutch 62 to the engaged state, thereby switching to 4WD state.

[0027] Figure 3 This is a flowchart illustrating an existing example of fail-safe control of the claw clutch 62 performed by the integrated ECU 82 in the electronic control unit 80 when an abnormality occurs, for example, repeated execution.

[0028] First, in step S101 (hereinafter, steps omitted), it is determined whether multiple faults have occurred in vehicle 10. If the determination in S101 is affirmative, in S102, vehicle 10 is shut down to an inoperable state, and this process ends.

[0029] If the determination in S101 is negative, in S103, it is determined whether a fault has occurred that prevents the claw clutch 62 from being engaged. This determination is made, for example, when the claw clutch 62 is engaged, if the rotation of the first dog tooth 62a and the second dog tooth 62b is asynchronous, that is, when the dog tooth rotation speed difference ΔNd, which is the absolute value of the difference between the rotation speeds of the first dog tooth Ndg1 and the second dog tooth Ndg2, is greater than a preset value N1 (ΔNd=|Ndg1-Ndg2|>N1), a fault is determined to have occurred. If the determination in S103 is positive, that is, if a fault has occurred that prevents the claw clutch 62 from being engaged, and the power transmission based on the claw clutch 62 cannot be ensured, in S104, a clutch control signal Sc is output to the clutch ECU 84 to put the claw clutch 62 into a released state, maintaining the released state in a fixed state, thus ending the process.

[0030] If the determination in S103 is negative, in S105, it is determined whether a fault has occurred that prevents the claw clutch 62 from being set to the released state. This determination is made, for example, when the claw clutch 62 is set to the released state, if the synchronization between the first dog tooth 62a and the second dog tooth 62b is not disengaged, i.e., when the dog tooth rotation speed difference ΔNd is less than a preset value N2 (ΔNd=|Ndg1-Ndg2|<N2), a fault is determined to have occurred. If the determination in S105 is positive, i.e., if a fault has occurred that prevents the claw clutch 62 from being set to the released state, and the engagement and disengagement of the claw clutch 62 cannot be ensured, in S106, a clutch control signal Sc is output to the clutch ECU 84 to put the claw clutch 62 into the engaged state, maintaining the engaged state in a fixed engagement state, thus ending the process.

[0031] If the determination in S105 is negative, in S107, it is determined whether the actuator 64 has malfunctioned. This determination is made, for example, by checking for abnormalities in the travel position Ldg or drive current Adg (or drive oil pressure Pdg) in the clutch operating information Ic. If an abnormality is found, it is determined that a malfunction has occurred. If the determination in S107 is positive, that is, if the actuator 64 has malfunctioned, the switching action between the engagement and disengagement states of the pawl clutch 62 cannot be ensured. In S108, the process is in a switching prohibition state that keeps the pawl clutch 62 in its current state, and the process ends.

[0032] If the determination in S107 is negative, i.e., no malfunction has occurred in actuator 64, in S109, it is determined whether there is a driving state switching request based on the driver's operation. If the determination in S109 is negative, the process ends. If the determination in S109 is positive, in S110, based on the driving state switching request—that is, in the case of a request to switch to 2WD state, the pawl clutch 62 is switched to the released state; in the case of a request to switch to 4WD state, the pawl clutch 62 is switched to the engaged state—the clutch control signal Sc is output to the clutch ECU 84, and the process ends.

[0033] In existing examples, in the event of a malfunction in the clutch mechanism 60 (claw clutch 62, actuator 64), as a fail-safe control for the claw clutch 62, controls are implemented as described above to set it to a released fixed state, an engaged fixed state, or a switching prohibited state. However, the fail-safe control in existing examples does not consider malfunctions other than those of the clutch mechanism 60. For example, in vehicle 10, if the first electric motor MG1 malfunctions in the 4WD state with the claw clutch 62 engaged, and the driver operates the driving state setting switch 94 to set the 2WD state in this state, the claw clutch 62 will be switched to the released state since the clutch mechanism 60 is functioning normally, potentially leading to the vehicle being unable to move. That is, even with malfunctions other than those of the clutch mechanism 60, depending on the location of the malfunction, if fail-safe measures are not properly implemented for the claw clutch 62, it could lead to the vehicle stopping on the road and affecting driver safety.

[0034] Figure 2 This is a flowchart illustrating an example of a fail-safe control operation of the claw clutch 62 performed by the integrated ECU 82 in the electronic control device 80 of this embodiment when an abnormality occurs, for example, repeated execution.

[0035] Control actions from S1 to S8 and S12 to S13 and Figure 3 In the existing example, the control actions of S101 to S108 and S109 to S110 are the same. Figure 2 The flowchart of this embodiment adds control actions S9 to S11 between S7 and S12. Therefore, the description of the same steps is omitted, and only the added steps are described.

[0036] If the judgment in S7 (whether a fault has occurred in actuator 64) is negative, in S9 and S10, it is sequentially determined whether a fault has occurred in either the second motor MG2 or the on-board charger 42. The judgment in S9 is, for example, performed by checking for abnormalities in the speed Nmg2, drive current Amg2, etc., in the MG2 operating information Img2 relative to the output of the MG2 control signal Smg2; if an abnormality is found, a fault is determined to have occurred. Similarly, the judgment in S10 is, for example, performed by checking for abnormalities in the charger operating information Ibc relative to the output of the charger control signal Sbc; if an abnormality is found, a fault is determined to have occurred. If the judgment in either S9 or S10 is positive, the process proceeds to S8, entering a switching prohibition state that keeps the claw clutch 62 in its current state, and the process ends. If either the second motor MG2 or the on-board charger 42 malfunctions, the switching operation of the claw clutch 62 cannot be guaranteed, and the claw clutch 62 is in a switching prohibition state, prohibiting switching operations.

[0037] If both S9 and S10 are negative, in S11, it is determined whether a fault has occurred in the first motor MG1. This determination is made, for example, by checking for abnormalities in the speed Nmg1, drive current Amg1, etc., in the MG1 operating information Img1 relative to the output of the MG1 control signal Smg1. If an abnormality is found, it is determined that a fault has occurred. If the determination in S11 is positive, that is, if the first motor MG1 has failed, in S6, a clutch control signal Sc is output to the clutch ECU84, causing the claw clutch 62 to be engaged, thereby maintaining the power transmission between the second motor MG2 and the front wheel 12, and keeping the claw clutch 62 in a fixed engaged state, thus ending the process.

[0038] If the judgment in S11 is negative, proceed to S12, and then execute the operation and the transition. Figure 3 (Existing example) S109 is the same control action.

[0039] Apart from Figure 2 Apart from the typical operation, preferably in cases where no fault has occurred but an event has occurred that restricts the switching action between the release and engagement states of the claw clutch 62, such as when the remaining charge (SOC) of the battery 40 drops below a specified level or when the internal temperature (Tmg2) of the second motor MG2 rises above a specified temperature, the claw clutch 62 is placed in a switching prohibition state. Thus, by restricting the switching action of the claw clutch 62, appropriate fail-safe control is implemented for the claw clutch 62.

[0040] Furthermore, the claw clutch 62 is preferably engaged and fixed when the lateral acceleration Gy or yaw acceleration Ryaw of the vehicle 10 is above a predetermined acceleration, or when the driving conditions or environment of the vehicle 10 are worse than usual, such as when driving on a low-friction road. This allows the vehicle to switch to 4WD mode under more stringent driving conditions or environments, thereby improving driving stability. The determination of driving on a low-friction road is made, for example, based on the variation trends of the left front wheel speed Nwfl, right front wheel speed Nwfr, left rear wheel speed Nwrl, and right rear wheel speed Nwrr, or information from road surface images obtained from the vehicle camera image information Iard of the vehicle camera 104. The road surface friction value RE is calculated according to a pre-preferred calculation method, and the determination is made by whether the road surface friction value RE is lower than a predetermined value Rn. The predetermined value Rn is a set value designed or experimentally calculated in advance for determining low-friction roads.

[0041] Furthermore, it is preferred to be in Figure 2In step S9, a malfunction of the second electric motor MG2 is detected. After the claw clutch 62 is in a switching-prohibited state in step S8, the claw clutch 62 is in a released and fixed state when the vehicle 10 stops moving. The stopping of the vehicle 10 is determined, for example, by the left front wheel speed Nwfl, right front wheel speed Nwfr, left rear wheel speed Nwrl, and right rear wheel speed Nwrr being below preset values. Therefore, when the vehicle 10 resumes movement after a stop, a malfunction of the second electric motor MG2 is avoided from hindering the movement of the vehicle 10.

[0042] Furthermore, preferably, in the event of a fault in the integrated ECU 82, the clutch ECU 84 puts the claw clutch 62 into a switching prohibition state. In the event of a fault in the integrated ECU 82, to ensure the smooth switching between the engagement and disengagement states of the claw clutch 62, the clutch ECU 84 puts the claw clutch 62 into a switching prohibition state, prohibiting switching operations. The fault in the integrated ECU 82 can be detected, for example, through a fault notification from the integrated ECU 82 or through a prolonged period of unresponsiveness.

[0043] As described above, the electronic control device 80 according to this embodiment performs fail-safe control as follows when an abnormality occurs: the claw clutch 62 is set to any of the following three states: a released fixed state where the clutch is in a released state and remains in the released state; an engaged fixed state where the clutch is in an engaged state and remains in the engaged state; and a switching prohibition state where the clutch remains in its current state. In the event of a fault that prevents the claw clutch 62 from being engaged, the claw clutch 62 is set to a released fixed state. In the event of a fault in the actuator 64, the claw clutch 62 is set to a switching prohibition state. In the event of a fault that prevents the claw clutch 62 from being released and a fault in the first electric motor MG1, the claw clutch 62 is set to an engaged fixed state. Therefore, in the event of a fault in the first electric motor MG1, the claw clutch 62 is set to an engaged fixed state, thus allowing for appropriate fail-safe control of the clutch mechanism 60, taking into account the fault location of the vehicle 10, such as by appropriately implementing avoidance maneuvers.

[0044] Furthermore, according to the electronic control device 80 of this embodiment, in the event of a fault in either the second electric motor MG2 or the on-board charger 42, the claw clutch 62 is placed in a switching prohibition state. In the event of a fault in either the second electric motor MG2 or the on-board charger 42, to ensure that the switching operation between the engagement and disengagement states of the claw clutch 62 cannot be guaranteed, appropriate fail-safe control is implemented for the claw clutch 62 by placing it in a switching prohibition state.

[0045] Furthermore, according to the electronic control device 80 of this embodiment, in the event of an event in which the switching action of the claw clutch 62 is restricted between the released and engaged states, even though no fault has occurred, such as a decrease in the remaining charge SOC of the battery 40 or an increase in the internal temperature Tmg2 of the second motor MG2, the claw clutch 62 is placed in a switching prohibition state. Thus, by restricting the switching action of the claw clutch 62, appropriate fail-safe control is implemented for the claw clutch 62.

[0046] Furthermore, according to the electronic control device 80 of this embodiment, when the driving conditions or driving environment of the vehicle 10 are more severe than usual, such as when the lateral acceleration Gy or yaw acceleration Ryaw of the vehicle 10 is large, or when driving on a low-friction road, the claw clutch 62 is engaged and fixed. Therefore, under more demanding driving conditions or driving environments, the system switches to 4WD mode, thereby improving driving stability.

[0047] Furthermore, according to the electronic control device 80 of this embodiment, when the claw clutch 62 is in a switching-prohibited state due to a malfunction of the second electric motor MG2, and the vehicle 10 stops moving, the claw clutch 62 is in a released and fixed state. Therefore, when the vehicle 10 resumes driving after stopping, the malfunction of the second electric motor MG2 is prevented from hindering the movement of the vehicle 10.

[0048] Furthermore, according to the electronic control device 80 of this embodiment, in the event of a malfunction in the integrated ECU 82, the clutch ECU 84 puts the claw clutch 62 into a switching prohibition state. In the event of a malfunction in the integrated ECU 82, to ensure the smooth switching between the engagement and disengagement states of the claw clutch 62, appropriate fail-safe control is implemented for the claw clutch 62 by putting it into a switching prohibition state through the clutch ECU 84.

[0049] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention can also be applied to other methods.

[0050] For example, in the aforementioned embodiments, the power source for the rear drive unit 30 may be an engine, in addition to or replacing the first electric motor MG1. Furthermore, the main drive wheel may be the front wheel 12, and the auxiliary drive wheel may be the rear wheel 14. In this case, the unit includes: a power source driving the front wheel 12; an electric motor driving the rear wheel 14; and a clutch disposed on the power transmission path between the rear wheel 14 and the electric motor.

[0051] Furthermore, the above is only one embodiment, and the present invention can be implemented in various ways with modifications and improvements based on the knowledge of those skilled in the art.

[0052] Symbol Explanation

[0053] 10 - Vehicle, 12 - Front wheel (auxiliary drive wheel), 14 - Rear wheel (main drive wheel), 40 - Battery, 42 - On-board charger, 62 - Claw clutch (clutch), 64 - Actuator, 80 - Electronic control unit (control unit), 82 - Integrated ECU, 84 - Clutch ECU, Gy - Lateral acceleration, MG1 - First electric motor (power source), MG2 - Second electric motor (electric motor), Ryaw - Yaw acceleration, SOC - Remaining battery charge, Tmg2 - Internal temperature.

Claims

1. A control device for a vehicle, the vehicle comprising: a power source driving a main drive wheel; an electric motor driving an auxiliary drive wheel; a battery for transmitting and receiving power between the battery and the electric motor; a clutch disposed on a power transmission path between the auxiliary drive wheel and the electric motor; and an actuator for switching between a disengaged state and an engaged state of the clutch, characterized in that... When an abnormality occurs, the control device performs the following fail-safe controls: a release-locked state where the clutch is in a released state and remains in the released state; an engagement-locked state where the clutch is in an engaged state and remains in the engaged state; and a switching prohibition state where the clutch remains in its current state. In the event of a fault that prevents the clutch from being engaged, the clutch is set to the released fixed state. In the event of a fault in the actuator, the clutch is set to the switching prohibited state. In the event of a fault that prevents the clutch from being engaged and a fault in the power source, the clutch is set to the engaged fixed state.

2. The vehicle control device according to claim 1, characterized in that, The vehicle also features: An on-board charger for charging the battery from an external power source of the vehicle. If the abnormality is a malfunction of either the electric motor or the on-board charger, the clutch will be set to the switching disabled state.

3. The vehicle control device according to claim 1, characterized in that, In the event that the abnormality is an event in which no fault has occurred but the switching action between the clutch's released and engaged states is restricted, the clutch is set to the switching prohibited state.

4. The vehicle control device according to claim 1, characterized in that, When the vehicle's driving conditions or driving environment are worse than usual, the vehicle sets the clutch to the engaged fixed state.

5. The vehicle control device according to claim 2, characterized in that, If the vehicle stops moving after the clutch is set to the switching prohibited state due to a malfunction of the electric motor, the clutch is set to the released fixed state.

6. The vehicle control device according to claim 1, characterized in that, The control device includes: a clutch ECU that controls the actuator; and an integrated ECU that controls vehicle-related systems including the power source, the electric motor, and the battery. In the event that the abnormality is a fault of the integrated ECU, the clutch ECU will set the clutch to the switching disabled state.

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