Vehicle control devices

Abstract

To provide a vehicle control device that can stably engage the clutch. [Solution] In the case of straight-line driving where the steering angle θsw of the vehicle 10 is less than or equal to a first predetermined value θn and the difference in front and rear wheel rotation speeds ΔNw is less than or equal to a second predetermined value NWn, the electronic control unit 80 calculates the synchronous rotation speed Ntgt from the MG1 rotation speed Nmg1. As a result, in the case of straight-line driving, the MG1 rotation sensor 94, which has high detection accuracy, is used instead of the second wheel speed sensor 92, which has low detection accuracy, in the engagement control of the dog clutch 60, and the rotation synchronization of the first dog teeth 60a and the second dog teeth 60b is performed with high accuracy, so that the engagement control of the dog clutch 60 is performed stably.

Description

Technical Field

[0001] The present invention relates to a control device for a vehicle including a power source that drives a main drive wheel, an electric motor that drives an auxiliary drive wheel, and a clutch provided in a power transmission path between the auxiliary drive wheel and the electric motor.

Background Art

[0002] A control device for a vehicle including a power source that drives a main drive wheel, an electric motor that drives an auxiliary drive wheel, and a clutch provided in a power transmission path between the auxiliary drive wheel and the electric motor is well known. For example, the drive vehicle for a vehicle described in Patent Document 1 is such a device. In this Patent Document 1, after controlling the electric motor so that the rotational speed of the electric motor estimated from the current and duty value of the electric motor matches the rotational speed corresponding to the wheel speed of the auxiliary drive wheel detected by a sensor, it is disclosed that an engagement-type clutch is engaged.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the aforementioned vehicle, clutch engagement occurs only after the rotational speeds of the opposing meshing teeth of the clutch are sufficiently close, that is, when the absolute value of the difference in rotational speeds falls below a permissible value. This is to suppress noise and shock, which occur when the clutch is engaged when the difference in rotational speeds is large. Conventionally, this difference in rotational speed was calculated using values ​​detected from a wheel speed sensor installed on the auxiliary drive wheel and values ​​detected from a rotational speed sensor (e.g., resolver) installed on the electric motor. However, since the wheel speed sensor has lower detection accuracy than the electric motor's rotational speed sensor, there was room for improvement in stably engaging the clutch while suppressing noise and shock. Furthermore, in order to compensate for the low detection accuracy of the wheel speed sensor, it was necessary to set the aforementioned permissible value small, which resulted in problems such as a deterioration in the responsiveness of clutch engagement.

[0005] The present invention was made against the above circumstances, and its objective is to provide a vehicle control device that can stably engage the clutch. [Means for solving the problem]

[0006] The gist of the first invention is a vehicle comprising (a) a power source for driving the main drive wheels, an electric motor for driving the auxiliary drive wheels, a meshing clutch provided in the power transmission path between the auxiliary drive wheels and the electric motor, a first wheel speed sensor for detecting the rotational speed of the main drive wheels as a first rotational speed, a second wheel speed sensor for detecting the rotational speed of the auxiliary drive wheels as a second rotational speed, a power source rotation sensor for detecting the rotational speed of the power source as a third rotational speed, and an electric motor rotation sensor for detecting the rotational speed of the electric motor as a fourth rotational speed, wherein the clutch is released In a vehicle control device that switches the clutch from a disengaged state to an engaged state, the difference between the synchronous rotational speed, which is the rotational speed of the meshing teeth on the auxiliary drive wheel side of the clutch, and the rotational speed of the meshing teeth on the motor side calculated from the fourth rotational speed is less than an allowable value, wherein (b) in the case of straight-line driving where the steering angle of the vehicle is less than or equal to a first predetermined value and the difference in front and rear wheel rotational speeds, which is the difference between the first rotational speed and the second rotational speed, is less than or equal to a second predetermined value, the synchronous rotational speed is calculated from the third rotational speed.

[0007] The gist of the second invention is that, in the case of turning, when the steering angle of the vehicle is greater than a first predetermined value or the difference in rotational speed between the front and rear wheels is greater than a second predetermined value, the vehicle control device calculates the synchronous rotational speed from the second rotational speed, and in the case of straight-line driving, the allowable value is made larger than in the case of turning. [Effects of the Invention]

[0008] According to the first invention, in the case of straight-line driving where the steering angle of the vehicle is less than or equal to a first predetermined value and the difference in front and rear wheel rotation speeds, which is the difference between the first rotation speed and the second rotation speed, is less than or equal to a second predetermined value, the synchronous rotation speed is calculated from the third rotation speed. As a result, in the case of straight-line driving, in the clutch engagement control, the power source rotation sensor with high detection accuracy is used instead of the second wheel speed sensor with low detection accuracy, and the synchronization of the rotation of the meshing teeth is performed with high accuracy, so that the clutch engagement control is performed stably.

[0009] According to the second invention, the vehicle control device calculates the synchronous rotational speed from the second rotational speed when the steering angle of the vehicle is greater than a first predetermined value or when the difference in rotational speed between the front and rear wheels is greater than a second predetermined value, and when the vehicle is driving straight, it sets the allowable value to be larger than when the vehicle is driving straight. As a result, the timing of determining the synchronization of the rotation of the meshing teeth is advanced, and the responsiveness of the clutch engagement is improved. [Brief explanation of the drawing]

[0010] [Figure 1] This diagram illustrates the schematic configuration of a vehicle to which the present invention is applied, as well as the control functions and key components of the control system for various control functions in the vehicle. [Figure 2] This flowchart illustrates an example of control operation during dog clutch engagement. [Figure 3] This is a time chart illustrating an example of control operation when the dog clutch is engaged. [Figure 4] This flowchart illustrates an example of the control operation of the subroutine that calculates the synchronous rotation speed, as shown in the flowchart in Figure 2. [Figure 5] This flowchart illustrates another embodiment of the subroutine used to calculate the synchronous rotational speed in the control operation of the electronic control unit shown in Figure 4. [Modes for carrying out the invention]

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Examples]

[0012] Figure 1 is a diagram illustrating the schematic configuration of a vehicle 10 to which the present invention is applied. In Figure 1, the vehicle 10 is equipped with left and right front wheels 12, a front drive unit 20 that drives the front wheels 12, left and right rear wheels 14, and a rear drive unit 30 that drives the rear wheels 14, all spaced apart from each other. The vehicle 10 is also equipped with a battery 40, which is a rechargeable DC power source. Note that "left and right" above refers to left and right with respect to the forward direction of the vehicle 10.

[0013] Vehicle 10 is an all-wheel drive vehicle in which the drive torque distribution between the front wheels 12 and the rear wheels 14 can be adjusted. All-wheel drive (AWD) and four-wheel drive (4WD) are synonymous. In addition to driving in 4WD mode, vehicle 10 can also drive in two-wheel drive (2WD) mode in which drive torque is distributed only to the rear wheels 14. The rear wheels 14 correspond to the "main drive wheels" of this invention, and the front wheels 12 correspond to the "secondary drive wheels" of this invention.

[0014] The front drive unit 20 comprises a second electric motor MG2 and a front PCU (Power Control Unit) 24. The second electric motor MG2 is a known rotating electric machine, a so-called motor generator, and is connected to the battery 40 via the front PCU 24. The second electric motor MG2 is the motor that drives the front wheels 12, which are auxiliary drive wheels. The front PCU 24 is a power control device that controls the power exchanged between the battery 40 and the second electric motor MG2. The front PCU 24 controls the power of the second electric motor MG2 by being controlled by the electronic control device 80 described later.

[0015] The front drive unit 20 includes a counter gear mechanism 50, a counter shaft 52, a final gear 54, a front differential gear (hereinafter referred to as front differential) 56, etc. The front drive unit 20 also includes left and right front drive shafts 58 connected to the front differential 56, etc. The counter gear mechanism 50 is a gear pair having a drive gear 50a and a driven gear 50b that meshes 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 counter 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 to the front wheels 12. The front drive unit 20 transmits power from the second electric motor MG2 to the front wheels 12.

[0016] The front drive unit 20 includes a dog clutch 60 and an actuator 62. The dog clutch 60 is a known meshing clutch provided in the power transmission path between the front wheel 12 and the second electric motor MG2. The actuator 62 controls the switching between the engaged and disengaged states of the dog clutch 60 by being controlled by the electronic control unit 80 described later. The dog clutch 60 corresponds to the "clutch" of the present invention.

[0017] The dog clutch 60 is provided, for example, in the power transmission path between the front differential 56 and the left front wheel 12. The dog clutch 60 has a first dog tooth 60a and a second dog tooth 60b as opposing meshing teeth. The first dog tooth 60a is connected to the front differential 56 and is the meshing tooth on the second electric motor MG2 side of the opposing meshing teeth. The second dog tooth 60b is connected to the left front drive shaft 58 and is the meshing tooth on the front wheel 12 side of the opposing meshing teeth. The dog clutch 60 is engaged when the first dog tooth 60a and the second dog tooth 60b mesh, and is released when their meshing is disengaged.

[0018] The rear drive device 30 includes a first electric motor MG1 and a rear PCU 34. The first electric motor MG1 is a known rotary electric machine, which is a so-called motor generator, and is connected to the battery 40 via the rear PCU 34. The first electric motor MG1 is a power source for driving the rear wheels 14, which are the main drive wheels. The rear PCU 34 has the same function as the front PCU 24, and controls the power of the first electric motor MG1 by being controlled by an electronic control device 80 described later.

[0019] The rear drive device 30 includes a counter gear mechanism 70, a counter shaft 72, a final gear 74, a rear differential gear 76, left and right rear drive shafts 78, etc. The rear drive device 30 has the same function as the front drive device 20, and transmits the power from the first electric motor MG1 to the rear wheels 14.

[0020] In the vehicle 10, the rear wheels 14 are driven when in the 2WD state and the 4WD state, and the front wheels 12 are driven only when in the 4WD state. The 4WD state is a driving state in which the front wheels 12 and the rear wheels 14 are driven in the engaged state of the dog clutch 60, and the power transmission path between the front wheels 12 and the second electric motor MG2 is in a connected state, that is, a connect state. The 2WD state is a driving state in which only the rear wheels 14 are driven in the released state of the dog clutch 60, and the power transmission path between the front wheels 12 and the second electric motor MG2 is in a disconnected state, that is, a disconnect state. By being in the disconnect state during the 2WD state, the rotation of the rotating members of the front drive device 20 on the side of the second electric motor MG2 and the rotation of the second electric motor MG2 are stopped. Thereby, the occurrence of power loss due to the rotation of the counter gear mechanism 50, the final gear 54, the front differential 56, etc. is prevented or suppressed. The dog clutch 60 is a disconnect mechanism capable of disconnecting the power transmission path between the front wheels 12 and the second electric motor MG2.

[0021] The vehicle 10 further includes an electronic control device 80 configured to include a so-called microcomputer as a vehicle control device of the vehicle 10.

[0022] The electronic control unit 80 is supplied with various signals based on the detection values ​​from various sensors provided in the vehicle 10. These various sensors include, for example, a first wheel speed sensor 90 provided on the rear wheel 14, a second wheel speed sensor 92 provided on the front wheel 12, an MG1 rotation sensor 94 provided on the first motor MG1, an MG2 rotation sensor 96 provided on the second motor MG2, an accelerator opening sensor 98, a brake sensor 100, and a steering angle sensor 102. The various signals include, for example, the rear wheel rotation speed Nwr, the front wheel rotation speed Nwf, the rotation speed of the first motor MG1 (MG1 rotation speed Nmg1), the rotation speed of the second motor MG2 (MG2 rotation speed Nmg2), the accelerator opening θacc, the brake operation amount Bra, and the steering wheel steering angle θsw. The MG1 rotation sensor 94 and the MG2 rotation sensor 96 are configured to include a known resolver that detects the rotation angle of the motor generator, and can detect the rotation speed with high accuracy. Furthermore, the MG1 rotational speed Nmg1 corresponds to the vehicle speed V of the vehicle 10, and the MG2 rotational speed Nmg2 corresponds to the disconnection rotational speed Ndg1, which is the rotational speed of the first dog tooth 60a. The MG1 rotation sensor 94 and the MG2 rotation sensor 96 correspond to the "power source rotation sensor" and the "motor rotation sensor" of the present invention, respectively. Also, the rear wheel rotational speed Nwr, the front wheel rotational speed Nwf, the MG1 rotational speed Nmg1, and the MG2 rotational speed Nmg2 correspond to the "first rotational speed," "second rotational speed," "third rotational speed," and "fourth rotational speed" of the present invention, respectively.

[0023] The electronic control unit 80 outputs various command signals to each device installed in the vehicle 10. These devices include, for example, the front PCU 24, the rear PCU 34, and the actuator 62. The various command signals include, for example, the MG2 control signal Smg2 for controlling the second motor MG2, the MG1 control signal Smg1 for controlling the first motor MG1, and the actuator control signal Sc for controlling the switching between the engaged and disengaged states of the dog clutch 60.

[0024] The electronic control unit 80 functionally includes a drive control unit 82, a dog control unit 84, and the like. The dog control unit 84 also functionally includes a dog calculation unit 86.

[0025] The drive control unit 82 calculates a required acceleration or a required deceleration for the vehicle 10 based on the accelerator opening θacc and / or the brake operation amount Bra, etc., and determines a switching of the drive state based on the required acceleration or deceleration, wheel slip, a driving mode selection by the driver, etc. For example, when the required acceleration or deceleration is increased during the 2WD state, the drive control unit 82 determines a switching to the 4WD state, and outputs a command to switch the dog clutch 60 to the engaged state to the dog control unit 84.

[0026] FIG. 2 is a flowchart for explaining an example of a control operation when the dog clutch is engaged, which is executed by the dog control unit 84. This flowchart is repeatedly executed, for example.

[0027] First, in step (hereinafter, steps are omitted) S1, it is determined whether there is a command to switch the dog clutch 60 to the engaged state. If this determination is negative, the determination in S1 is repeated. If the determination in S1 is affirmative, in S2, a subroutine (to be described later) is executed by the dog calculation unit 86 to calculate the synchronous rotation speed Ntgt, which is the rotation speed of the second dog tooth 60b, and the synchronous rotation speed Ntgt is calculated. Next, in S3, the second electric motor MG2 is driven so that the rotation of the first dog tooth 60a and the second dog tooth 60b is synchronized, that is, so that the disengagement / engagement rotation speed Ndg1 of the first dog tooth 60a becomes the synchronous rotation speed Ntgt, and the MG2 rotation speed Nmg2 is increased. Then, in S4, it is determined whether the absolute value of the difference between the synchronous rotation speed Ntgt and the disengagement / engagement rotation speed Ndg1, that is, the dog rotation speed difference ΔNdg, is less than the allowable value Nlmt (ΔNdg = |Ntgt - Ndg1| < Nlmt). The allowable value Nlmt is a threshold value for determining the start of engagement of the dog clutch 60, and a suitable value obtained in advance by design or experiment is set. If the determination in S4 is negative, S2 and below are repeated. If the determination in S4 is affirmative, in S5, the actuator 62 is operated so that the dog clutch 60 is in the engaged state, the dog clutch 60 is switched to the engaged state, and this routine is terminated.

[0028] FIG. 3 is a time chart for explaining an example of the control operation at the time of engagement of the dog clutch 60 performed by the electronic control unit 80 when switching the vehicle 10 from the 2WD state to the 4WD state.

[0029] In FIG. 3, starting from traveling at a vehicle speed V of V0, an acceleration operation by the driver (the accelerator opening θacc increases from θ1 to θ2) is performed from time t0, and acceleration starts due to an increase in the driving torque of the first motor MG1. Then, in accordance with the acceleration request, the drive control unit 82 determines at time t1 to switch to the 4WD state, and the driving (torque application) of the second motor MG2 starts at time t1. As the rotational speed Nmg2 of MG2 increases, the disengagement / engagement rotational speed Ndg1 of the first dog tooth 60a is increased so as to become the synchronous rotational speed Ntgt of the second dog tooth 60b. Then, at time t2 when the dog rotational speed difference ΔNdg becomes less than the allowable value Nlmt (ΔNdg = |Ntgt - Ndg1| < Nlmt), the operation of the actuator 62 is started so as to engage the dog clutch 60. Then, after the meshing operation (see the inset in FIG. 3) due to the top surface contact between the first dog tooth 60a and the second dog tooth 60b, the switching to the engaged state of the dog clutch 60 is performed at time t3.

[0030] By the way, in the engagement control of the dog clutch 60, conventionally, the synchronous rotational speed Ntgt has been calculated from the front wheel rotational speed Nwf detected by the second wheel speed sensor 92. However, since the wheel speed sensor (the second wheel speed sensor 92) has lower detection accuracy than the rotational speed sensor (for example, a resolver) provided in the motor or the like, the detection accuracy of the dog rotational speed difference ΔNdg becomes low. As a result, there has been room for improvement in stably engaging the dog clutch 60 while suppressing noise and shock. Also, in order to compensate for the low detection accuracy of the wheel speed sensor (the second wheel speed sensor 92), it has been necessary to set the allowable value Nlmt small. As a result, there has also been a problem that the timing at time t2 in FIG. 3 becomes late, that is, the responsiveness of the engagement of the dog clutch 60 deteriorates.

[0031] Therefore, in this embodiment, the electronic control device 80, through the control operation described later in Figure 4, stabilizes the engagement of the dog clutch 60 when the vehicle 10 is traveling in a straight line by calculating the synchronous rotational speed Ntgt from the MG1 rotational speed Nmg1.

[0032] Figure 4 is a flowchart illustrating the control operation of the subroutine that calculates the synchronous rotation speed Ntgt, which is executed by the dog calculation unit 86 at S2 in the flowchart of Figure 2.

[0033] First, in S10, it is determined whether the steering angle θsw is small or not. This determination is made, for example, by determining whether the absolute value of the steering angle θsw is less than or equal to the first predetermined value θn (|Nmg1-Nmg2|≦θn). If the determination in S10 is affirmative, in S20, it is determined whether the front-to-rear wheel rotation speed difference ΔNw, which is the absolute value of the difference between the rear wheel rotation speed Nwr and the front wheel rotation speed Nwf, is small or not, that is, whether the front-to-rear wheel rotation speed difference ΔNw is less than or equal to the second predetermined value NWn (ΔNw=|Nwr-Nwf|≦NWn). If the determination in S20 is affirmative, that is, if both the determinations in S10 and S20 are affirmative, in S30, it is determined that the vehicle 10 is traveling in a straight line, the synchronous rotation speed Ntgt is calculated from the MG1 rotation speed Nmg1, and this routine returns. The calculation of the synchronous rotation speed Ntgt from the MG1 rotation speed Nmg1 is performed, for example, by calculating the vehicle speed V corresponding to the MG1 rotation speed Nmg1, and then calculating the synchronous rotation speed Ntgt corresponding to the calculated vehicle speed V. If at least one of the judgments in S10 and S20 is rejected, in S40 it is determined that the vehicle 10 is turning, the synchronous rotation speed Ntgt is calculated from the front wheel rotation speed Nwf, and this routine returns. The first predetermined value θn and the second predetermined value NWn are set values ​​that have been determined in advance, either by design or experiment, to suitably determine whether the vehicle 10 is moving straight or turning.

[0034] When the vehicle 10 is traveling in a straight line, the MG1 rotation sensor 94, which has high detection accuracy, is used instead of the second wheel speed sensor 92, which has low detection accuracy, in the engagement control of the dog clutch 60. As a result, the rotation of the first dog teeth 60a and the second dog teeth 60b is synchronized with high accuracy, and the engagement control of the dog clutch 60 is performed stably. Furthermore, when the vehicle 10 is traveling in a turn, the difference in front and rear wheel rotation speeds ΔNw increases with the turn, so the difference between the synchronous rotation speed Ntgt calculated from the MG1 rotation speed Nmg1 and the actual synchronous rotation speed Ntgt (hereinafter referred to as the turning deviation difference) increases, and the detection accuracy of the dog rotation speed difference ΔNdg deteriorates. For this reason, when traveling in a turn, the second wheel speed sensor 92, which does not generate a turning deviation difference, is used, and the engagement control of the dog clutch 60 is performed stably.

[0035] As described above, according to the electronic control device 80 of this embodiment, in the case of straight-line driving where the steering angle θsw of the vehicle 10 is less than or equal to a first predetermined value θn and the front and rear wheel rotation speed difference ΔNw is less than or equal to a second predetermined value NWn, the synchronous rotation speed Ntgt is calculated from the MG1 rotation speed Nmg1. As a result, in the case of straight-line driving, the MG1 rotation sensor 94, which has high detection accuracy, is used instead of the second wheel speed sensor 92, which has low detection accuracy, in the engagement control of the dog clutch 60, and the rotation synchronization of the first dog teeth 60a and the second dog teeth 60b is performed with high accuracy, so that the engagement control of the dog clutch 60 is performed stably. Furthermore, in the case of turning driving where the steering angle θsw of the vehicle 10 is greater than the first predetermined value θn, or the front and rear wheel rotation speed difference ΔNw is greater than the second predetermined value NWn, the synchronous rotation speed Ntgt is calculated from the front wheel rotation speed Nwf. As a result, when turning, the second wheel speed sensor 92, which does not cause a turning deviation, is used, allowing for stable engagement control of the dog clutch 60.

[0036] Next, other embodiments of the present invention will be described. In the following description, parts common to multiple embodiments will be denoted by the same reference numerals and their descriptions will be omitted. [Examples]

[0037] Figure 5 is a flowchart illustrating a control operation example different from that of Example 1 (Figure 4) of the subroutine that calculates the synchronous rotation speed Ntgt, which is executed by the dog calculation unit 86 at S2 in the flowchart of Figure 2.

[0038] This embodiment is an example in which S500 is added after S300, which corresponds to S30, and S600 is added after S400, which corresponds to S40, to the flowchart of Embodiment 1 (Figure 4).

[0039] In Figure 5, at S600, following S400 where turning is determined, the allowable value Nlmt is set to a predetermined value NB, and the routine returns. The predetermined value NB is the allowable value when synchronization is determined using the synchronous rotation speed Ntgt calculated from the front wheel rotation speed Nwf, and is determined in advance through design or experiment. Similarly, at S500, following S300 where straight-line driving is determined, the allowable value Nlmt is set to a predetermined value NA (NA>NB), which is greater than the predetermined value NB, and the routine returns. The predetermined value NA is the allowable value when synchronization is determined using the synchronous rotation speed Ntgt calculated from the MG1 rotation speed Nmg1, and is determined in advance through design or experiment. Since the detection accuracy of the MG1 rotation speed Nmg1 is higher than that of the front wheel rotation speed Nwf, the detection of the dog rotation speed difference ΔNdg can be performed with high accuracy. Therefore, when calculating from the MG1 rotational speed Nmg1, the detection accuracy is higher than when calculating from the front wheel rotational speed Nwf, allowing for a larger tolerance value Nlmt (Nlmt = NA > NB). As a result, the timing at time t2 in Figure 3, i.e., the timing of the synchronization determination of the rotation of the first dog tooth 60a and the second dog tooth 60b, is accelerated, improving the responsiveness of the engagement of the dog clutch 60.

[0040] As described above, according to the electronic control device 80 of this embodiment, in the case of straight-line driving where the steering angle θsw of the vehicle 10 is less than or equal to a first predetermined value θn and the difference in front and rear wheel rotation speeds ΔNw is less than or equal to a second predetermined value NWn, the synchronous rotation speed Ntgt is calculated from the MG1 rotation speed Nmg1. In the case of turning driving where the steering angle θsw of the vehicle 10 is greater than the first predetermined value θn, or the difference in front and rear wheel rotation speeds ΔNw is greater than the second predetermined value NWn, the synchronous rotation speed Ntgt is calculated from the front wheel rotation speed Nwf. In the case of straight-line driving, the allowable value Nlmt is made larger than in the case of turning driving. As a result, in addition to the effects of Embodiment 1 described above, the timing of the synchronization determination of the rotation of the first dog tooth 60a and the second dog tooth 60b is advanced, so the responsiveness of the engagement of the dog clutch 60 is improved.

[0041] Although embodiments of the present invention have been described in detail above with reference to the drawings, the present invention is also applicable to other embodiments.

[0042] For example, in the above-described embodiments 1 and 2, the power source for the rear drive unit 30 may be an engine in addition to, for example, the first electric motor MG1. Alternatively, the main drive wheels may be the front wheels 12 and the secondary drive wheels may be the rear wheels 14. In this case, the system includes a power source for driving the front wheels 12, an electric motor for driving the rear wheels 14, and a clutch provided in the power transmission path between the rear wheels 14 and the electric motor.

[0043] It should be noted that the above-described embodiment is merely one example, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art. [Explanation of symbols]

[0044] 10: Vehicle 12: Front wheels (auxiliary drive wheels) 14: Rear wheels (main drive wheels) 60: Dog clutch (clutch) 80: Electronic control unit (vehicle control unit) 90: First wheel speed sensor 92: Second wheel speed sensor 94: MG1 rotation sensor (power source rotation sensor) 96: MG2 rotation sensor (motor rotation sensor) MG1: First motor (power source) MG2: Second motor (motor) Nlmt: Allowable value Nmg1: MG1 rotation speed (third rotation speed) Nmg2: MG2 rotation speed (fourth rotation speed) Ntgt: Synchronous rotation speed Nwf: Front wheel rotation speed (second rotation speed) NWn: Second predetermined value Nwr: Rear wheel rotation speed (first rotation speed) ΔNw: Front and rear wheel rotation speed difference θn: First predetermined value θsw: Steering angle

Claims

1. A vehicle comprising a power source for driving the main drive wheels, an electric motor for driving the auxiliary drive wheels, a meshing clutch provided in the power transmission path between the auxiliary drive wheels and the electric motor, a first wheel speed sensor for detecting the rotational speed of the main drive wheels as a first rotational speed, a second wheel speed sensor for detecting the rotational speed of the auxiliary drive wheels as a second rotational speed, a power source rotation sensor for detecting the rotational speed of the power source as a third rotational speed, and an electric motor rotation sensor for detecting the rotational speed of the electric motor as a fourth rotational speed, wherein when switching the clutch from a disengaged state to an engaged state, the vehicle control device controls the clutch to be switched to an engaged state when the difference between the synchronous rotational speed, which is the rotational speed of the meshing teeth on the auxiliary drive wheel side of the clutch, and the rotational speed of the meshing teeth on the electric motor side calculated from the fourth rotational speed, is less than an allowable value, In the case of straight-line driving where the steering angle of the vehicle is less than or equal to a first predetermined value and the difference in front and rear wheel rotation speeds, which is the difference between the first rotation speed and the second rotation speed, is less than or equal to a second predetermined value, the synchronous rotation speed is calculated from the third rotation speed. A vehicle control device characterized by the following features.

2. The vehicle control device calculates the synchronous rotational speed from the second rotational speed when the steering angle of the vehicle is greater than a first predetermined value, or when the difference in rotational speed between the front and rear wheels is greater than a second predetermined value. In the case of straight-line driving, the allowable value is made larger than in the case of turning driving. The vehicle control device according to feature 1.

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