Vehicular driving device

Abstract

To prevent heat-generation control from influencing behavior of a vehicle while performing the control during running of the vehicle.SOLUTION: When executing heat-generation control, a control part of a vehicular driving device controls a first rotary electric machine so that the machine generates first cancelling / driving force and controls a second rotary electric machine so that the machine generates second cancelling / driving force that acts on the opposite side of a running direction of the vehicle with respect to the first cancelling / driving force. In executing the heat-generation control, when required driving force (Trq) is larger than a switching restriction range (SWLim), the control part performs regenerative control of the first rotary electric machine and performs powering-control of the second rotary electric machine, during acceleration of the vehicle, and performs powering-control of the first rotary electric machine and performs regenerative control of the second rotary electric machine, during deceleration of the vehicle. In executing the heat-generation control, when the required driving force is within the switching restriction range (SWLim), the control part keeps on performing the regenerative control or the powering-control of the first rotary electric machine and the second rotary electric machine in the heat-generation control executed in the last minutes, without switching.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a vehicle drive device including a first rotating electric machine drivingly connected to one of front wheels and rear wheels, and a second rotating electric machine drivingly connected to the other of the wheels. [Background technology]

[0002] For example, in a vehicle drive device mounted on an electric vehicle, when the temperature of the battery is low, the efficiency of charging and discharging decreases. In particular, when the battery is extremely cold (for example, below 0 degrees), it becomes difficult to charge the battery, and even when the vehicle decelerates while traveling, regeneration cannot be performed, resulting in a problem of reduced power consumption. For this reason, when traveling a vehicle that has been left in a low-temperature environment for a long time, for example, it is required to warm up the vehicle quickly, but it is more difficult to warm up an electric vehicle than a hybrid vehicle that is equipped with an internal combustion engine as a heat source. Therefore, a device has been proposed that, while the vehicle is stopped or traveling, a d-axis current is passed through the traveling motor in addition to the q-axis current that provides driving force, thereby warming up the traveling motor extra, thereby accelerating the warming up of the battery (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-165526 ​​A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above-mentioned Patent Document 1, in which a d-axis current is passed to warm up a driving motor, the increase in the amount of heat generated by the driving motor is limited, and the warm-up time is long, particularly in an extremely low-temperature environment, making it insufficient for practical use. For this reason, it is possible to warm up the battery by installing a high-voltage heater, for example, but high-voltage heaters are expensive and hinder cost reduction of the vehicle. For this reason, it is possible to warm up the vehicle by controlling a front motor that drives the front wheels and a rear motor that drives the rear wheels to generate driving forces that cancel each other out (hereinafter referred to as "heat generation control").

[0005] In a vehicle equipped with a vehicle drive device having a front motor and a rear motor, the vehicle weight is likely to be applied to the front wheels of the vehicle. For this reason, power running control is performed with the front motor (front wheels) when the vehicle accelerates, and regenerative control is performed with the front motor when the vehicle decelerates, thereby improving the electricity consumption. However, for example, when the above-mentioned heat generation control is being performed while the vehicle is traveling, if the required driving force switches between the acceleration direction and the deceleration direction, the directions of the generated driving forces also switch so as to cancel each other out, which may affect the behavior of the vehicle.

[0006] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide a vehicle drive device that is capable of performing heat generation control while the vehicle is traveling, while preventing any effect on the behavior of the vehicle. [Means for solving the problem]

[0007] One aspect of the present invention relates to a vehicle having a first rotating electric machine that is drivingly connected to one of the front wheels and the rear wheels of a vehicle, a second rotating electric machine that is driven independently of the first rotating electric machine and is drivingly connected to the other of the front wheels and the rear wheels, and a control unit that controls the first rotating electric machine and the second rotating electric machine, wherein, when performing heat generation control to warm up the vehicle, the control unit controls the first rotating electric machine to generate a first counteracting driving force, and controls the second rotating electric machine to generate a second counteracting driving force that acts on the opposite side of the vehicle's traveling direction with respect to the first counteracting driving force, and when performing the heat generation control during acceleration of the vehicle, the required driving force is This is a vehicle drive device that, when the required deceleration force is greater than the switching limit range in the acceleration direction, regeneratively controls the first rotating electric machine and powers the second rotating electric machine, and when executing the heat generation control during deceleration of the vehicle, if the required deceleration force is greater than the switching limit range in the deceleration direction of the vehicle, powers the first rotating electric machine and regeneratively controls the second rotating electric machine, and when executing the heat generation control and the required driving force is within the switching limit range, continues the regenerative control or powering control of the first rotating electric machine and the second rotating electric machine in the heat generation control that was executed immediately before without switching. Effect of the Invention

[0008] According to the present invention, it is possible to perform heat generation control while the vehicle is running, while preventing the behavior of the vehicle from being affected. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic diagram showing the configuration of a vehicle and a vehicle drive device according to a first embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing a state in which the vehicle according to the first embodiment is stopped. [Diagram 3] 2A to 2C are schematic diagrams showing states during acceleration and steady running while the vehicle according to the first embodiment is running forward. [Figure 4] FIG. 2 is a schematic diagram showing a state in which the vehicle according to the first embodiment is decelerating while traveling forward. [Diagram 5] FIG. 2 is a schematic diagram showing a state in which the vehicle according to the first embodiment is being charged while stopped. [Figure 6] FIG. 2 is a schematic diagram showing a state during acceleration while the vehicle according to the first embodiment is traveling backward. [Figure 7] 4 is a flowchart showing ON / OFF control of heat creation control according to the first embodiment. [Figure 8] 4 is a flowchart showing vehicle state control according to the first embodiment. [Figure 9] 10 is a time chart showing an example of driving when heat generation control according to the second embodiment is executed. [Figure 10] 5 is a time chart showing an example of driving when heat generation control according to a comparative example is executed; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] First Embodiment A vehicle drive device 1 according to a first embodiment will be described below with reference to FIGS. 1 to 8. FIG.

[0011] [Vehicle configuration] First, the configuration of a vehicle 100 on which the vehicle drive device 1 is mounted will be described with reference to FIG. 1. FIG. 1 is a schematic diagram showing the configuration of a vehicle according to the first embodiment and the vehicle drive device. As shown in FIG. 1, the vehicle 100, which is a four-wheel drive electric vehicle on which the vehicle drive device 1 is mounted, travels forward in the upward direction in the figure, and includes left and right front wheels 7FL, 7FR, left and right rear wheels 7RL, 7RR, a battery unit 20, the vehicle drive device 1 that drives the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR using the power of the battery unit 20, a compressor 30 for air conditioning the interior of the vehicle, and the like. In addition, brakes 9, such as disc brakes, are provided on the left and right front wheels 7FL, 7FR and the left and right rear wheels 7RL, 7RR, respectively, as an example of a brake device.

[0012] Vehicle 100 is also provided with a driver's seat 50, which is shown in a simplified manner, and is provided with a shift lever 51, an accelerator pedal 52, a brake pedal 53, etc. Shift lever 51 is configured to allow the driver to select a shift range, such as a parking range, a neutral range, a drive range, or a reverse range, and transmits a signal of the selected shift range to ECU 10, which will be described in detail later. Accelerator pedal 52 is also configured to be able to detect the accelerator opening, and transmits a signal of the accelerator opening to ECU 10. ECU 10, having received the signal, detects the driver's requested driving force in the accelerating direction of vehicle 100 (hereinafter, the requested driving force in the accelerating direction will be referred to as "requested driving force Trq") based on the accelerator opening. Furthermore, the brake pedal 53 is configured to be able to detect the brake pressure and transmits a signal of the brake pressure to the ECU 10. The ECU 10, upon receiving the signal, detects the driver's requested driving force in the deceleration direction of the vehicle 100 (hereinafter, the requested driving force in the deceleration direction will be referred to as "requested deceleration force Tdec") based on the brake pressure.

[0013] In addition, the parking range and neutral range are non-driving ranges that prevent the vehicle 100 from driving, the drive range is a forward range (driving range) that causes the vehicle 100 to drive forward, and the reverse range is a reverse range (driving range) that causes the vehicle 100 to drive backward.

[0014] In addition, in this embodiment, the required driving force Trq is described as being detected based on the accelerator opening, which is the amount of operation of the accelerator pedal 52 by the driver. However, this is not limited to this, and the required driving force Trq may be determined by the control unit, for example, by automatic driving, cruise control, etc.

[0015] Similarly, in this embodiment, the required deceleration force Tdec is described as being detected based on the brake pedal pressure, which is the amount of operation of the brake pedal 53 by the driver, but this is not limited to the above, and the required deceleration force Tdec may be determined by the control unit, for example, by automatic driving, cruise control, etc.

[0016] The vehicle drive device 1 includes a front motor 2, which is a three-phase brushless DC motor as a first rotating electric machine (motor generator) drivingly connected to the front wheels 7FL, 7FR, a rear motor 3, which is a three-phase brushless DC motor as a second rotating electric machine (motor generator) that is driven independently of the front motor 2 and is drivingly connected to the left and right rear wheels 7RL, 7RR, a drive circuit 5 that can freely control the drive force (regenerative force) by supplying a drive current (electric power) to the front motor 2 and the rear motor 3, and a control unit (ECU) 10 that can control the drive circuit 5. That is, the front motor 2 is configured to be able to rotate and drive the front wheels 7FL, 7FR or to generate regenerative power, and the rear motor 3 is configured to be able to rotate and drive the left and right rear wheels 7RL, 7RR or to generate regenerative power. The drive circuit 5 is also configured to be able to directly supply a drive current (electric power) to a compressor 30 without passing through a battery unit 20.

[0017] 1, the front motor 2 and the rear motor 3 are simply shown as motors, but are generally configured as drive units equipped with a reduction gear mechanism, a differential device, etc., which are not shown. In addition, the control unit 10 that performs various controls in this embodiment is described as being provided in the vehicle drive device 1, but may be another control unit provided in the vehicle 100.

[0018] [Vehicle state control] Next, in the first embodiment, state control for transitioning between modes according to the state of the vehicle 100, which is controlled by the control unit 10 of the vehicle drive device 1, will be described with reference to Fig. 8. Fig. 8 is a flowchart showing the vehicle state control according to the first embodiment. Note that the vehicle state control shown in Fig. 8 is repeatedly executed at predetermined time intervals according to the processing speed of the control unit 10, for example, and the state set in each mode transitions as the judgment changes.

[0019] In detail, as shown in Fig. 8, when the start switch of the vehicle 100 is turned on, the control unit 10 starts this state control, and first, based on a signal from a position detection sensor (not shown), determines whether the position of the shift lever 51 is in a non-driving range such as a parking range or a neutral range (S11). Next, when the control unit 10 determines that the shift lever 51 is in a non-driving range (YES in S11), it determines whether the vehicle is being charged (S12). When the control unit 10 determines that the vehicle 100 is connected to an external charger 200 (Fig. 5), that is, when the vehicle is being charged (YES in S12), it sets the state of the vehicle 100 to a charging mode (S14). When the control unit 10 determines that the vehicle is not being charged (NO in S12), it sets the state of the vehicle 100 to a stop mode (S15).

[0020] On the other hand, when the control unit 10 determines that the vehicle is not in the non-driving range based on the position of the shift lever 51 (NO in S11), it determines whether the vehicle is in the drive range (forward range) based on the position of the shift lever 51 (S13). When the control unit 10 determines that the vehicle is in the drive range (YES in S13), it sets the state of the vehicle 100 to the forward mode (S16), and when the control unit 10 determines that the vehicle is not in the drive range (NO in S13), that is, the vehicle is in the reverse range (reverse range), it sets the state of the vehicle 100 to the reverse mode (S17). When the vehicle 100 is in the forward mode or reverse mode, it can distinguish between a state in which the vehicle 100 is accelerating or steadily running based on the required driving force Trq and a state in which the vehicle 100 is decelerating based on the required deceleration force Tdec.

[0021] [Heat generation control ON / OFF control] Next, the ON / OFF control of the heat creation control for warming up the vehicle 100, which is controlled by the control unit 10 of the vehicle drive device 1 in the first embodiment, will be described with reference to Fig. 7. Fig. 7 is a flowchart showing the ON / OFF control of the heat creation control according to the first embodiment. Note that the ON / OFF control of the heat creation control shown in Fig. 7 is also repeatedly executed at predetermined time intervals according to the processing speed of the control unit 10, for example, and the ON / OFF of the heat creation control is switched as the judgment changes.

[0022] 7, for example, when the start switch of the vehicle 100 is turned on, the control unit 10 starts ON / OFF control of the heat creation control, and first determines whether the air conditioning in the vehicle 100 is ON (S1). If the air conditioning is ON (YES in S1), the control unit 10 determines whether the temperature of the coolant circulating through the front motor 2, rear motor 3, battery unit 20, drive circuit 5, compressor 30, etc. is less than 40 degrees (S2). If the air conditioning is ON (YES in S1) and the coolant temperature is less than 40 degrees (YES in S2), the control unit 10 determines that the heat creation control is ON because the heat used for heating by the air conditioning cannot be obtained from the coolant, that is, executes the heat creation control (S4).

[0023] Furthermore, when the air conditioning is not ON (NO in S1), or when the air conditioning is ON but the water temperature is 40 degrees or higher (YES in S1 and NO in S2), the control unit 10 determines whether the temperature of the battery unit 20 (i.e., the battery) is below 0 degrees (S3). Even in this case, if the temperature of the battery unit 20 is below 0 degrees (YES in S3), the control unit 10 determines to turn on the heat creation control, that is, executes the heat creation control (S4). Then, when the temperature of the battery unit 20 is 0 degrees or higher (NO in S3), the control unit 10 determines to turn off the heat creation control, that is, does not execute the heat creation control (S5), and sets the vehicle in a normal driving state.

[0024] [Problems with general motor heat control] Here, problems with general motor heat generation control will be described. The front motor 2 and rear motor 3 according to the first embodiment are configured as three-phase brushless DC motors. In general, when a three-phase brushless DC motor is used to generate heat without outputting torque, a current larger than normal is passed only to a single-phase coil while the vehicle is stopped to generate heat. However, when a large current is passed through a single-phase coil while the vehicle is stopped, for example, when the vehicle moves slightly due to some external cause, causing a change in rotation of the motor, a large driving force is output from the motor, which may cause a shock or the like. In addition, when the vehicle is started, a local driving force is generated by the single-phase coil, and even if a command is issued to control the rotation smoothly, it is difficult to make the current control follow the local driving force. Furthermore, since the control is performed by passing a current only through a single-phase coil, there is also a problem that it takes a long time to warm up the motor when the amount of heat generated is small and the motor, battery unit, coolant, etc. are at extremely low temperatures. Therefore, when it is determined that the heat creation control is ON as described above and it is decided to execute the heat creation control, in the first embodiment, the following heat creation control is executed in each mode.

[0025] [When heat generation control is executed] Next, detailed operations during execution of heat generation control in the first embodiment will be described with reference to Figs. 2 to 6. In the following description, heat generation is basically performed by reversing the output direction of the driving force of the front motor 2 and the rear motor 3 relative to the vehicle travel direction to cancel each other out, but since the detailed operations differ in each driving state (each mode), each driving state (each mode) will be described separately. Generally, the battery unit 20 has a property that, although it is difficult to charge when it is in a low temperature state below 0 degrees, it can output electricity if there is a remaining charge. For this reason, in the heat generation control described below, the control unit 10 controls the battery unit 20 to output electric power but not to charge the battery unit 20.

[0026] (Heat generation control when stationary) First, the operation of the heat generation control in a state where the vehicle 100 is stopped without charging (stop mode) will be described with reference to Fig. 2. Fig. 2 is a schematic diagram showing a state when the vehicle according to the first embodiment is stopped. In the stop mode shown in Fig. 2, the brake pedal 53 is depressed and the brake 9 is ON (operated and locked) (BRK ON), or the brake 9 of the vehicle 100 is ON (locked) by brake hold or the like even if the brake pedal 53 is not depressed, or other brakes (so-called parking brakes or side brakes) (not shown) are ON (locked), and the left and right front wheels 7FL, 7FR and the left and right rear wheels 7RL, 7RR of the vehicle 100 are forcibly fixed.

[0027] When the control unit 10 determines the stop mode through the vehicle state control and determines that the heat generation control is ON through the ON / OFF control of the heat generation control, as shown in Figure 2, it powers the front motor 2 using the power of the battery unit 20 so that the front motor 2 generates a backward driving force TF1 as a first counteracting driving force Tcan1 at the left and right front wheels 7FL, 7FR, and powers the rear motor 3 using the power of the battery unit 20 so that, while synchronized with the front motor 2, the rear motor 3 generates a forward driving force TR1 as a second counteracting driving force Tcan2 acting on the opposite side of the traveling direction of the vehicle 100 and having the same magnitude as the driving force TF1 at the front wheels 7FL, 7FR.

[0028] In this case, it is safer if the driving force TF1 of the front wheels 7FL, 7FR output by the front motor 2 and the driving force TR1 of the rear wheels 7RL, 7RR output by the rear motor 3 are smaller than the braking force that stops the rotation of the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR by turning on the brake 9, for example, but since these driving forces TF1 and TR1 are in a direction that cancels each other out, they may be larger than the braking force of the brake 9. In addition, it is preferable that the rotation speeds of the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR are detected by an ABS sensor (not shown) or the like, and when it is determined that the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR are not rotating, the driving of the front motor 2 and the rear motor 3 by this heat generation control is permitted, and when the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR rotate due to slippage, for example, the driving of the front motor 2 and the rear motor 3 is stopped.

[0029] In addition, in this stop mode, the front motor 2 and the rear motor 3 are powered and no power is generated by regeneration from the front motor 2 as in the drive mode described in detail below, and therefore the compressor 30 is not driven. However, it is possible to drive the compressor 30 using power from the battery unit 20 to heat the interior of the vehicle.

[0030] As described above, in heat generation control in the stop mode, the driving force TF1 of the front wheels 7FL, 7FR by the front motor 2 and the driving force TR1 of the rear wheels 7RL, 7RR by the rear motor 3 are output so as to cancel each other out in the direction of travel of the vehicle 100. This makes it possible to pass a larger current through the front motor 2 and the rear motor 3 than when current is passed through, for example, a single-phase coil. This allows the amount of heat generated during warm-up to be increased, and the warm-up time to be shortened.

[0031] (Heat generation control during acceleration and steady driving while driving forward) Next, the operation of the heat generation control in a state (forward mode) in which the vehicle 100 is accelerating or running steadily while traveling forward will be described with reference to FIG. 3. FIG. 3 is a schematic diagram showing a state during acceleration and steady running of the vehicle according to the first embodiment during forward running. In the forward mode shown in FIG. 3, the brake pedal 53 is not depressed and the brake 9 is OFF (released) (BRK OFF), and other brakes (so-called parking brakes and side brakes) not shown in particular are also OFF (released), and the left and right front wheels 7FL, 7FR and the left and right rear wheels 7RL, 7RR of the vehicle 100 are rotatable. In addition, steady running is a state in which the running resistance of the vehicle 100 and the driving force in the accelerating direction (required driving force Trq) are in balance, and in a broad sense, the operation of the vehicle 100 is the same as that during acceleration. Furthermore, if the running resistance of the vehicle 100 is greater than the driving force in the accelerating direction (required driving force Trq), the speed of the vehicle 100 will decrease, but in a broad sense, the operation of the vehicle 100 can be said to be in the same state as when accelerating.

[0032] When the control unit 10 determines the forward mode by the vehicle state control and determines the ON of the heat generation control by the ON / OFF control of the heat generation control, and determines that there is a required driving force Trq based on the accelerator opening degree of the accelerator pedal 52, as shown in Fig. 3, the control unit 10 controls the rear motor 3 using the power of the battery unit 20 so that a forward driving force TR2, which is the sum of the second counteracting driving force Tcan2 and the required driving force Trq, is generated by the rear motor 3 at the left and right rear wheels 7RL, 7RR, as shown in Fig. 3, and controls the front motor 2 to regenerate so that a backward driving force TF2 as the first counteracting driving force Tcan1 is generated by the front motor 2 at the left and right front wheels 7FL, 7FR while synchronizing with the powering control of the rear motor 3. In other words, the control unit 10 sets the magnitude of the powering of the rear motor 3 and the regeneration of the front motor 2 so that the difference between the driving force TR2 of the rear wheels 7RL, 7RR by the rear motor 3 and the driving force TF2 of the front wheels 7FL, 7FR by the front motor 2 becomes the required driving force Trq. That is, while generating a driving force TF2 for the front wheels 7FL, 7FR from the front motor 2, a driving force TR2 for the rear wheels 7RL, 7RR is generated from the rear motor 3 so as to be larger than the driving force TF2 for the front wheels 7FL, 7FR. Note that, although it depends on the output performance of the front motor 2 and the rear motor 3, it is preferable to set so that the required driving force Trq is generated as the driving force for the vehicle 100 according to the limit value of either one of them.

[0033] During acceleration or steady driving during forward driving, the rear motor 3 is supplied with power from the battery unit 20, but the power regenerated by the front motor 2 is also supplied to the rear motor 3 via the drive circuit 5. Therefore, the amount of power consumed by the battery unit 20 can be significantly reduced compared to, for example, when both the front motor 2 and the rear motor 3 are powered. In addition, by supplying a portion of the power regenerated by the front motor 2 to the compressor 30, the vehicle interior can be air-conditioned (heated) without using the power of the battery unit 20. In particular, for example, when the vehicle 100 is accelerating while traveling downhill, the front motor 2 can perform regeneration, so that even if the battery unit 20, which is in a low temperature state, cannot be charged, power can be supplied to the compressor 30, and the vehicle interior can be air-conditioned (heated) without increasing the power consumption of the battery unit 20. Therefore, by controlling the front motor 2 to regenerate in this manner, the electric power consumption of the vehicle can be improved.

[0034] Furthermore, even during acceleration during forward travel and steady travel, it is preferable to detect the rotational speeds of the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR using an ABS sensor (not shown) or the like, and if it is determined that the deviation in the rotational speeds of the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR is small, to permit regeneration of the front motor 2 and driving (powering) of the rear motor 3 through this heat generation control, and to stop regeneration of the front motor 2 and driving of the rear motor 3 if the deviation in the rotational speeds of the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR becomes large due to, for example, slippage, etc.

[0035] In the first embodiment, the front motor 2 performs regeneration while the rear motor 3 performs powering, but the front motor 2 may perform powering while the rear motor 3 performs regeneration. However, although it depends on the weight distribution between the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR of the vehicle 100, regeneration by the front motor 2 generally has higher regeneration efficiency and can improve electricity consumption. In addition, the control unit 10 may control the front motor 2 and the rear motor 3 to switch between powering and regeneration during travel depending on the travel situation, such as cornering, travelling uphill, travelling downhill, etc., including deceleration during forward travel, which will be described later.

[0036] As described above, in heat generation control during acceleration and steady driving during forward driving (driving mode), the driving force TF2 for the front wheels 7FL, 7FR by the front motor 2 and the driving force TR2 for the rear wheels 7RL, 7RR by the rear motor 3 are output so as to cancel each other out in the traveling direction of the vehicle 100, which makes it possible to pass a larger current through the front motor 2 and the rear motor 3 than when a current is passed through, for example, a single-phase coil, so that the amount of heat generated during warm-up can be increased and the warm-up time can be shortened. Also, in this heat generation control during acceleration and steady driving during forward driving (driving mode), regeneration is performed by the front motor 2, thereby improving the electric power consumption of the vehicle.

[0037] (Heat generation control during deceleration while driving forward) Next, the operation of the heat generation control in a state where the vehicle 100 is decelerating while traveling forward (forward mode) will be described with reference to Fig. 4. Fig. 4 is a schematic diagram showing a state when the vehicle according to the first embodiment is decelerating while traveling forward. In the forward mode shown in Fig. 4, the brake pedal 53 is depressed and the brake 9 is ON (activated and slipping) (BRK ON), and other brakes (not shown, in particular so-called parking brakes and side brakes) are OFF (released), and the left and right front wheels 7FL, 7FR and the left and right rear wheels 7RL, 7RR of the vehicle 100 are rotating.

[0038] When the control unit 10 determines the forward mode by the vehicle state control and determines the ON of the heat generation control by the ON / OFF control of the heat generation control, and determines that there is a required deceleration force Tdec based on the amount of depression of the brake pedal 53, etc., it controls the rear motor 3 using the power of the battery unit 20 so that the rear motor 3 generates a forward driving force TR3 as a second counteracting driving force Tcan2 on the left and right rear wheels 7RL, 7RR, as shown in Fig. 4, and regeneratively controls the front motor 2 so that the front motor 2 generates a backward driving force TF3 as a first counteracting driving force Tcan1 on the left and right front wheels 7FL, 7FR while synchronizing with the power running control of the rear motor 3. That is, the control unit 10 controls so that the driving force TR3 of the rear wheels 7RL, 7RR by the rear motor 3 and the driving force TF3 of the front wheels 7FL, 7FR by the front motor 2 are the same in magnitude, thereby controlling so that the required deceleration force Tdec is generated by the braking force of the brake 9. Also, although it depends on the output performance of the front motor 2 and the rear motor 3, it is preferable to set the magnitude of regeneration of the front motor 2 and power running of the rear motor 3 according to the limit value of one of them.

[0039] During this deceleration while traveling forward, a small amount of power is supplied from the battery unit 20 to the rear motor 3, but essentially, power regenerated by the front motor 2 is supplied to the rear motor 3 via the drive circuit 5. For this reason, the amount of power consumed by the battery unit 20 is small, and can be significantly reduced compared to, for example, when both the front motor 2 and the rear motor 3 are powered. Also, as during acceleration while traveling forward, by supplying a portion of the power regenerated by the front motor 2 to the compressor 30, it is possible to perform air conditioning (heating) inside the vehicle without using power from the battery unit 20. Therefore, by controlling the front motor 2 to regenerate in this manner, it is possible to improve the electric power consumption of the vehicle.

[0040] Even when decelerating during forward travel, it is preferable to detect the rotational speeds of the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR using an ABS sensor (not shown), and if it is determined that the deviation in the rotational speeds of the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR is small, to permit regeneration of the front motor 2 through this heat generation control and driving (powering) of the rear motor 3, and to stop regeneration of the front motor 2 and driving of the rear motor 3 if the deviation in the rotational speeds of the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR becomes large due to, for example, slippage, etc.

[0041] Similarly, in the first embodiment, regeneration is performed by the front motor 2 while powering is performed by the rear motor 3, but the reverse may be true: regeneration is performed by the rear motor 3 while powering is performed by the front motor 2. However, although it depends on the weight distribution between the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR of the vehicle 100, regeneration by the front motor 2 generally has higher regeneration efficiency and can improve electricity consumption. Furthermore, the control unit 10 may control the powering and regeneration of the front motor 2 and the rear motor 3 to be switched during traveling depending on the traveling conditions, such as cornering, traveling uphill, traveling downhill, etc., including during acceleration during forward traveling and during steady traveling as described above.

[0042] As described above, in heat generation control during deceleration during forward travel (travel mode), the driving force TF3 of the front wheels 7FL, 7FR by the front motor 2 and the driving force TR3 of the rear wheels 7RL, 7RR by the rear motor 3 are output so as to cancel each other out in the traveling direction of the vehicle 100, which makes it possible to pass a larger current through the front motor 2 and the rear motor 3 than when a current is passed through, for example, a single-phase coil, so that the amount of heat generated during warm-up can be increased and the warm-up time can be shortened. Also, in this heat generation control during deceleration during forward travel (travel mode), regeneration is performed by the front motor 2, thereby improving the electric power consumption of the vehicle.

[0043] (Control of heat generation during charging) Next, the operation of the heat generation control in a state (charging mode) in which the vehicle 100 is charging and stopped will be described with reference to Fig. 5. Fig. 5 is a schematic diagram showing a state in which the vehicle according to the first embodiment is charging while stopped. In the charging mode shown in Fig. 5, as in the above-mentioned stopped state, the brake pedal 53 is depressed and the brake 9 is ON (locked) (BRK ON), or even if the brake pedal 53 is not depressed, the brake 9 of the vehicle 100 is ON (locked) by brake hold or the like, or other brakes (so-called parking brakes or side brakes) not shown are ON (locked), and the left and right front wheels 7FL, 7FR and the left and right rear wheels 7RL, 7RR of the vehicle 100 are forcibly fixed.

[0044] As described above, it is difficult to charge the battery unit 20 at low temperatures. Therefore, in this charging mode, the purpose is to warm up the battery unit 20 in particular with the power of the charger 200 so that the battery unit 20 can be charged by the charger 200.

[0045] When the control unit 10 determines the charging mode through the vehicle state control and determines that the heat generation control is ON through the ON / OFF control of the heat generation control, as shown in Figure 5, it powers the front motor 2 using the power of the charger 200 so that the front motor 2 generates a backward driving force TF1 as a first counteracting driving force Tcan1 at the left and right front wheels 7FL, 7FR, and powers the rear motor 3 using the power of the charger 200 so that, while synchronized with the front motor 2, the rear motor 3 generates a forward driving force TR1 as a second counteracting driving force Tcan2 that is the same magnitude as the driving force TF1 of the front wheels 7FL, 7FR.

[0046] As in the case of stopping the vehicle, it is safer for the driving force TF1 of the front wheels 7FL, 7FR output by the front motor 2 and the driving force TR1 of the rear wheels 7RL, 7RR output by the rear motor 3 to be smaller than the braking force that stops the rotation of the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR by turning on the brake 9, but since the driving forces TF1 and TR1 cancel each other out, they may be larger than the braking force of the brake 9. Also, when the rotation speeds of the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR are detected by an ABS sensor (not shown) or the like and it is determined that the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR are not rotating, it is preferable to permit the driving of the front motor 2 and the rear motor 3 by this heat generation control, and to stop the driving of the front motor 2 and the rear motor 3 when the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR rotate due to slippage, for example.

[0047] In addition, in this charging mode, if the driving force TF1 on the front wheels 7FL, 7FR by the front motor 2 and the driving force TR1 on the rear wheels 7RL, 7RR by the rear motor 3 are the same as those during the stop state, it is possible to perform simple control of simply switching the power supply source from the charger 200 to the battery unit 20 when charging is terminated and the vehicle transitions to the stop mode. However, this is not limited to the above, and since the charging mode can accept power from the charger 200 that is greater than the output performance of the battery unit 20, such as in quick charging, the driving forces generated in the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR may be made larger than in the stop mode, and in this case the warm-up period can be shortened.

[0048] In addition, in this charging mode, as in the stop mode described above, the front motor 2 and the rear motor 3 are powered and controlled, i.e., no power is generated by regeneration of the front motor 2, so the compressor 30 is not driven; however, the compressor 30 may be driven using power from the charger 200 to heat the interior of the vehicle.

[0049] As described above, even in heat generation control in charging mode, by outputting the driving force TF1 of the front wheels 7FL, 7FR by the front motor 2 and the driving force TR1 of the rear wheels 7RL, 7RR by the rear motor 3 so as to cancel each other out in the direction of travel of the vehicle 100, it is possible to pass a larger current through the front motor 2 and the rear motor 3 than when current is passed through, for example, a single-phase coil. This makes it possible to increase the amount of heat generated during warm-up and shorten the warm-up time.

[0050] (Heat generation control while reversing) Finally, the operation of the heat generation control in a state where the vehicle 100 is accelerating or running steadily while traveling backward (reverse mode) will be described with reference to Fig. 6. Fig. 6 is a schematic diagram showing a state when the vehicle according to the first embodiment is accelerating while traveling backward. In the reverse mode shown in Fig. 6, the brake pedal 53 is not depressed and the brake 9 is OFF (released) (BRK OFF), and other brakes (not shown, so-called parking brakes and side brakes) are also OFF (released), and the left and right front wheels 7FL, 7FR and the left and right rear wheels 7RL, 7RR of the vehicle 100 are rotatable.

[0051] In this heat generation control during acceleration and steady driving while traveling in reverse, the roles (relationship) of the front motor 2 and the rear motor 3 are reversed compared to the heat generation control during acceleration and steady driving while traveling forward described above (see Figure 3).

[0052] That is, when the control unit 10 determines the reverse mode through the vehicle state control and determines that the heat generation control is ON through the heat generation control ON / OFF control, and determines that there is a required driving force Trq based on the accelerator opening degree of the accelerator pedal 52, etc., it controls the front motor 2 using the power of the battery unit 20 so that the front motor 2 generates a reverse driving force TF4, which is the sum of the first counteracting driving force Tcan1 and the required driving force Trq, to ​​the left and right front wheels 7FL, 7FR, as shown in Figure 6, and regeneratively controls the rear motor 3 so that the rear motor 3 generates a forward driving force TR4 as a second counteracting driving force Tcan2 to the left and right rear wheels 7RL, 7RR, while synchronizing with the powering control of the front motor 2.

[0053] Other than this, the operation is the same as the heat generation control during acceleration and steady running in the forward mode (see FIG. 3) except that the operations of the front motor 2 and the rear motor 3 are reversed. Also, although not shown, deceleration during reverse running is the same as the heat generation control during acceleration and steady running in the forward mode (see FIG. 4) except that the operations of the front motor 2 and the rear motor 3 are reversed.

[0054] In this way, in heat generation control during reverse running (driving mode), the driving force TF4 of the front wheels 7FL, 7FR by the front motor 2 and the driving force TR4 of the rear wheels 7RL, 7RR by the rear motor 3 are output so as to cancel each other out in the traveling direction of the vehicle 100, which makes it possible to pass a larger current through the front motor 2 and the rear motor 3 than when a current is passed through, for example, a single-phase coil, so that the amount of heat generated during warm-up can be increased and the warm-up time can be shortened. Also, in this heat generation control during reverse running (driving mode), regeneration is performed by the rear motor 3, thereby improving the electric power consumption of the vehicle.

[0055] <Second embodiment> Next, a second embodiment, which is a partial modification of the first embodiment, will be described with reference to Figs. 9 and 10. Fig. 9 is a time chart showing an example of driving when heat generation control according to the second embodiment is executed. Fig. 10 is a time chart showing an example of driving when heat generation control according to a comparative example is executed. In the description of the second embodiment, the same reference numerals are used for parts similar to those of the first embodiment, and the description thereof will be omitted.

[0056] In the above-described vehicle drive device 1 according to the first embodiment, in the heat generation control during acceleration during forward driving and during steady driving (see FIG. 3), the second counteracting driving force Tcan2 is added to the required driving force Trq and output from the rear motor 3, that is, the vehicle is driven and controlled as a rear-wheel drive type vehicle. On the other hand, in the vehicle drive device 1 according to the second embodiment, except when the required driving force described below falls within a limited range, the front motor 2 adds the first counteracting driving force Tcan1 to the required driving force Trq and outputs it by powering control, and the rear motor 3 generates the second counteracting driving force Tcan2 by regenerative control, that is, the vehicle is driven and controlled as a front-wheel drive type vehicle. In this case, the driving force TF2 of the front wheels 7FL, 7FR is output toward the front of the vehicle 100, and the driving force TR2 of the rear wheels 7RL, 7RR is output toward the rear of the vehicle 100.

[0057] In the vehicle drive device 1 according to the second embodiment, similarly to the first embodiment, except when the required driving force described below falls within the limited range, in the heat generation control during deceleration during forward driving (see FIG. 4), a first cancellation driving force Tcan1 is generated from the front motor 2 by regenerative control, and a second cancellation driving force Tcan2 is generated from the rear motor 3 by powering control.

[0058] (Driving example in comparative example) Here, a driving example in the comparative example will be described with reference to FIG. 10, and a problem in the comparative example will be described. As shown in FIG. 10, for example, when the vehicle 100 is traveling forward with the forward range selected and the heat generation control is inactive, the ECU 10 calculates the sum of the driving force TF of the front wheels and the driving force TR of the rear wheels to be the required driving force Trq according to the depression amount (accelerator opening) of the accelerator pedal 52, and performs power running control so that the driving force TF is output from the front motor 2 and power running control so that the driving force TR is output from the rear motor 3. As a result, the front wheel actual driving force TFr is output according to the driving force TF calculated from the front wheels 7FL, 7FR, and the rear wheel actual driving force TRr is output according to the driving force TR calculated from the rear wheels 7RL, 7RR. That is, when accelerating forward traveling in this heat generation control inactive state, the vehicle 100 is in a state of accelerating in four-wheel drive.

[0059] For example, at time t31, when the ECU 10 determines to start heat generation control (see S4 in FIG. 7), the heat generation control during acceleration while traveling is started. Then, the ECU 10 calculates the sum of the driving force TF of the front wheels and the driving force TR of the rear wheels to be the required driving force Trq according to the required driving force Trq (i.e., the required driving force in the acceleration direction). That is, as described above, in the heat generation control during acceleration while traveling forward, the ECU 10 sets it so that the first counteracting driving force Tcan1 and the required driving force Trq are generated from the front wheels 7FL, 7FR by powering control of the front motor 2, and the second counteracting driving force Tcan2 is generated from the rear wheels 7RL, 7RR by regenerative control of the rear motor 3. At this time, the sum of the first counteracting driving force Tcan1 and the required driving force Trq (i.e., the driving force TF of the front wheels) is set to the powering limit driving force TlimP which is the performance limit of the front motor 2 (or the limit determined by the remaining charge of the battery unit 20, etc.), and the second counteracting driving force Tcan2 is set to be the same magnitude as the first counteracting driving force Tcan1. As a result, from time t31 to time t32, the actual front wheel driving force TFr becomes the powering limit driving force TlimP which is a driving force in the acceleration direction, and the actual rear wheel driving force TRr becomes the second counteracting driving force Tcan2 which is a driving force in the deceleration direction.

[0060] After that, for example, from time t32 to time t33, the driver reduces the depression amount of the accelerator pedal 52, and at time t33, the brake pedal 53 is depressed to turn on the brake 9, and the heat generation control during acceleration while traveling is switched to the heat generation control during deceleration while traveling. Then, from time t33 to time t37, the ECU 10 calculates the sum of the driving force TF of the front wheels and the driving force TR of the rear wheels according to the required deceleration force Tdec (i.e., the required driving force in the deceleration direction) so that the required deceleration force Tdec is the sum of the driving force TF of the front wheels and the driving force TR of the rear wheels. That is, in the heat generation control during deceleration while traveling forward as described above, the ECU 10 sets it so that the first counteracting driving force Tcan1 and the required deceleration force Tdec are generated from the front wheels 7FL, 7FR by regeneratively controlling the front motor 2, and the second counteracting driving force Tcan2 of the same magnitude as the first counteracting driving force Tcan1 is generated from the rear wheels 7RL, 7RR by powering control of the rear motor 3. At this time, the sum of the first counteracting driving force Tcan1 and the required deceleration force Tdec (i.e., the driving force TF of the front wheels) is set to the regenerative limit driving force TlimR, which is the performance limit of the front motor 2 (or the limit determined by the remaining charge of the battery unit 20, etc.). In addition, since the driving force TF that the front motor 2 can generate does not exceed the regenerative limit driving force TlimR, when the required deceleration force Tdec increases, as in the case from time t34 to time t36, the first counteracting driving force Tcan1 decreases accordingly, and the driving force TR of the rear wheels that outputs the second counteracting driving force Tcan2 also decreases accordingly. As a result, from time t33 to time t35, the actual front wheel driving force TFr becomes the regenerative limit driving force TlimR, which is the driving force in the deceleration direction, and the actual rear wheel driving force TRr becomes the second counteracting driving force Tcan2, which is the driving force in the acceleration direction.

[0061] Next, for example, from time t36, the driver reduces the depression amount of the brake pedal 53, and at time t37, the brake 9 is turned off and the accelerator pedal 52 is pressed, and the required driving force Trq increases, and the heat generation control during deceleration while traveling is switched to the heat generation control during acceleration while traveling. Then, similar to the time from time T31 to time t33, the front motor 2 is powered to generate the first counteracting driving force Tcan1 and the required driving force Trq from the front wheels 7FL, 7FR, while the rear motor 3 is regeneratively controlled to generate the second counteracting driving force Tcan2 from the rear wheels 7RL, 7RR. Furthermore, for example, from time t38, the driver reduces the depression amount of the accelerator pedal 52, and at time t39, the brake pedal 53 is pressed to turn on the brake 9, and the heat generation control during acceleration while traveling is switched to the heat generation control during deceleration while traveling. As a result, from time t37 to time t39, the front wheel actual driving force TFr moves toward the powering limit driving force TlimP, which is a driving force in the acceleration direction, while the rear wheel actual driving force TRr moves toward the second cancellation driving force Tcan2, which is a driving force in the deceleration direction, and then at time t39, the trends reverse, and the front wheel actual driving force TFr moves toward the regenerative limit driving force TlimR, which is a driving force in the deceleration direction, while the rear wheel actual driving force TRr moves toward the second cancellation driving force Tcan2, which is a driving force in the acceleration direction.

[0062] If the driver subsequently increases the depression amount of the brake pedal 53 from time t39 to time t41, that is, if the required deceleration force Tdec increases, then at time t40 the front wheel actual driving force TFr becomes the regenerative limit driving force TlimR, which is a driving force in the deceleration direction, and the rear wheel actual driving force TRr becomes the second counteracting driving force Tcan2, which is a driving force in the acceleration direction. Also, since the driving force TF that the front motor 2 can generate does not exceed the regenerative limit driving force TlimR, if the required deceleration force Tdec increases as from time t39 to time t41, the first counteracting driving force Tcan1 decreases accordingly, and the driving force TR of the rear wheels that outputs the second counteracting driving force Tcan2 also decreases accordingly.

[0063] As described above, in the traveling example of the comparative example, the ECU 10 executes heat generation control during acceleration while traveling when the required driving force Trq is a positive value and is a required driving force in the acceleration direction, and executes heat generation control during deceleration while traveling when the required driving force Trq is a negative value and is a required driving force in the deceleration direction (when the required deceleration force Tdec occurs). In other words, when the required driving force Trq switches between the acceleration direction and the deceleration direction, the directions of the first counteracting driving force Tcan1 and the second counteracting driving force Tcan2 that are generated to cancel each other out are also switched, which may affect the behavior of the vehicle.

[0064] (Driving example in the second embodiment) Next, a driving example in the second embodiment will be described with reference to Fig. 9. Fig. 9 is a time chart showing a driving example when heat generation control in the second embodiment is being executed.

[0065] In the second embodiment, when the required driving force Trq in the acceleration direction of the vehicle 100 is greater than the range of the switching limit range SWlim (for example, the range of 20 Nm to -20 Nm), the front motor 2 is powered and the rear motor 3 is regeneratively controlled to generate the first counteracting driving force Tcan1 and the second counteracting driving force Tcan2 as described above. When the required driving force Trq in the deceleration direction of the vehicle 100 (i.e., the required deceleration force Tdec) is greater than the range of the switching limit range SWlim, the front motor 2 is regeneratively controlled and the rear motor 3 is powered and controlled to generate the first counteracting driving force Tcan1 and the second counteracting driving force Tcan2 as described above. When the required driving force Trq falls within the switching limit range SWlim, the regenerative control or powering control of the front motor 2 and the rear motor 3 in the heat generation control executed immediately before is continued as it is without switching.

[0066] In addition, it is preferable to determine the range of the switching limit range SWlim depending on the reduction ratio between the front motor 2 and the front wheels 7FL, 7FR and the reduction ratio between the rear motor 3 and the rear wheels 7RL, 7RR, as well as the frequency of hunting that occurs depending on the torque responsiveness and torque accuracy of the front motor 2 and the rear motor 3, etc.

[0067] In addition, when the required driving force Trq falls within the switching limit range SWlim, the magnitude of the driving force of the front motor 2 (i.e., the driving force TF of the front wheels) and the driving force of the rear motor 3 (i.e., the driving force TR of the rear wheels) is limited to be within the driving force limit range TlimSW.

[0068] 9, for example, when the vehicle 100 is traveling forward with the forward range selected and the heat generation control is inactive, the ECU 10 calculates the sum of the front wheel driving force TF and the rear wheel driving force TR to be the required driving force Trq according to the depression amount (accelerator opening) of the accelerator pedal 52, and performs powering control so that the driving force TF is output from the front motor 2 and the driving force TR is output from the rear motor 3. As a result, the front wheel actual driving force TFr is output according to the driving force TF calculated from the front wheels 7FL, 7FR, and the rear wheel actual driving force TRr is output according to the driving force TR calculated from the rear wheels 7RL, 7RR. In other words, when accelerating forward traveling in this heat generation control inactive state, the vehicle 100 is accelerated in four-wheel drive.

[0069] For example, at time t11, when the ECU 10 determines to start heat generation control (see S4 in FIG. 7), the heat generation control during acceleration while traveling is started. Then, the ECU 10 calculates the sum of the driving force TF of the front wheels and the driving force TR of the rear wheels according to the required driving force Trq (i.e., the required driving force in the acceleration direction) so that the required driving force Trq is the sum of the driving force TF of the front wheels and the driving force TR of the rear wheels. That is, as described above, in the heat generation control during acceleration while traveling forward, the ECU 10 sets it so that the first counteracting driving force Tcan1 and the required driving force Trq are generated from the front wheels 7FL, 7FR by powering control of the front motor 2, and the second counteracting driving force Tcan2 is generated from the rear wheels 7RL, 7RR by regenerative control of the rear motor 3. At this time, the sum of the first counteracting driving force Tcan1 and the required driving force Trq (i.e., the driving force TF of the front wheels) is set to the powering limit driving force TlimP which is the performance limit of the front motor 2 (or the limit determined by the remaining charge of the battery unit 20, etc.), and the second counteracting driving force Tcan2 is set to be the same magnitude as the first counteracting driving force Tcan1. As a result, from time t11 to time t12, the actual front wheel driving force TFr becomes the powering limit driving force TlimP which is a driving force in the acceleration direction, and the actual rear wheel driving force TRr becomes the second counteracting driving force Tcan2 which is a driving force in the deceleration direction.

[0070] After that, for example, from time t12 to time t13, the driver reduces the depression amount of the accelerator pedal 52, and when the required driving force Trq falls within the switching limit range SWlim at time t13, the ECU 10 limits the magnitude of the front wheel driving force TF and the rear wheel driving force TR to be within the driving force limit range TlimSW. As a result, while the front motor 2 is powered, the total driving force of the first counteracting driving force Tcan1 and the required driving force Trq output from the front wheels 7FL, 7FR is limited within the driving force limit range TlimSW, that is, the first counteracting driving force Tcan1 is limited to be significantly small. In addition, since the first counteracting driving force Tcan1 is limited to be small, the second counteracting driving force Tcan2, which is set to the same magnitude as the first counteracting driving force Tcan1, also falls within the driving force limit range TlimSW. As a result, from time t13 to time t14, the front wheel actual driving force TFr becomes a driving force in the acceleration direction that is the limit driving force of the driving force limit range TlimSW, and the rear wheel actual driving force TRr becomes a second cancellation driving force Tcan2 that is a driving force in the deceleration direction.

[0071] Next, for example, when the driver depresses the brake pedal 53 at time t14 to turn on the brake 9, the required driving force Trq becomes a negative value, that is, the required deceleration force Tdec is generated and the vehicle 100 enters a deceleration state, but since the required driving force Trq is within the switching limit range SWlim, the ECU 10 continues the powering control of the front motor 2 and the regenerative control of the rear motor 3 in the state that was executed just before the required driving force Trq entered the switching limit range SWlim, that is, the heat generation control during acceleration. Therefore, the ECU 10 controls so that the first counteracting driving force Tcan1 is output from the front wheels 7FL, 7FR, and the second counteracting driving force Tcan2 and the required deceleration force Tdec are generated from the rear wheels 7RL, 7RR. In this state, the total driving force of the second counteracting driving force Tcan2 and the required deceleration force Tdec output from the rear wheels 7RL, 7RR is limited to within the driving force limit range TlimSW, that is, the second counteracting driving force Tcan2 is limited to a significantly smaller value. Furthermore, since the second counteracting driving force Tcan2 is limited to a small value, the first counteracting driving force Tcan1, which is set to the same magnitude as the second counteracting driving force Tcan2, also falls within the driving force limit range TlimSW.

[0072] Furthermore, for example, from time t17, if the driver reduces the amount of depression of the brake pedal 53, and at time t18 turns off the brake 9 and depresses the accelerator pedal 52, the required driving force Trq will increase, and from time t18 to t19 the required driving force Trq will increase and become a positive value until time t20, that is, the vehicle 100 will be in an accelerating state, but since the ECU 10 continues heat generation control during acceleration, the powering control of the front motor 2 and the regenerative control of the rear motor 3 will continue. Furthermore, thereafter, for example, at time t20, if the driver again depresses the brake pedal 53 to turn on the brake 9, the required driving force Trq becomes negative, that is, a required deceleration force Tdec is generated and the vehicle 100 enters a deceleration state. However, since the required driving force Trq remains within the switching limit range SWlim, the ECU 10 continues the powering control of the front motor 2 and the regenerative control of the rear motor 3 in the state that was being executed just before the required driving force Trq entered the switching limit range SWlim, that is, in the heat generation control during acceleration.

[0073] Then, for example, when the driver increases the depression amount of the brake pedal 53 and the required deceleration force Tdec (required driving force Trq in the deceleration direction) exceeds the range of the switching limit range SWlim at time t21, the ECU 10 transitions from a state similar to the heat generation control during acceleration while traveling to the above-mentioned heat generation control during deceleration while traveling. That is, the state in which the front motor 2 is powered and the rear motor 3 is regeneratively controlled is switched to a state in which the front motor 2 is regeneratively controlled and the rear motor 3 is powered. Then, after time t21, the ECU 10 calculates the sum of the driving force TF of the front wheels and the driving force TR of the rear wheels to be the required deceleration force Tdec according to the required deceleration force Tdec (i.e., the required driving force in the deceleration direction). That is, as described above, in the heat generation control during deceleration during forward travel, the ECU 10 sets the front motor 2 to regeneratively control the front wheels 7FL, 7FR to generate the first counteracting driving force Tcan1 and the required deceleration force Tdec, while the rear motor 3 is powered to control the rear wheels 7RL, 7RR to generate the second counteracting driving force Tcan2 having the same magnitude as the first counteracting driving force Tcan1. The sum of the first counteracting driving force Tcan1 and the required deceleration force Tdec (i.e., the driving force TF of the front wheels) at this time is set to the regenerative limit driving force TlimR, which is the performance limit of the front motor 2 (or the limit determined by the remaining charge of the battery unit 20, etc.). In addition, since the driving force TF that the front motor 2 can generate does not exceed the regenerative limit driving force TlimR, when the required deceleration force Tdec increases as from time t21 to time t22, the first counteracting driving force Tcan1 decreases accordingly, and the driving force TR of the rear wheels that outputs the second counteracting driving force Tcan2 also decreases accordingly. As a result, from time t21 to time t22, the front wheel actual driving force TFr becomes the regenerative limit driving force TlimR, which is a driving force in the deceleration direction, and the rear wheel actual driving force TRr becomes the second cancellation driving force Tcan2, which is a driving force in the acceleration direction.

[0074] Thereafter, when the required driving force Trq becomes larger than the switching limit range SWlim in a state where the front motor 2 is regeneratively controlled and the rear motor 3 is powered, the system transitions from a state similar to the heat generation control during deceleration while traveling to the heat generation control during acceleration while traveling described above. In other words, the system switches from a state where the front motor 2 is regeneratively controlled and the rear motor 3 is powered to a state where the front motor 2 is powered and the rear motor 3 is regeneratively controlled. This state is similar to the state from time t11 to time t21, and therefore description thereof will be omitted.

[0075] As described above, in the second embodiment, when the required driving force Trq falls within the switching limit range SWlim, the regenerative control or power running control of the front motor 2 and the rear motor 3 in the heat generation control that was executed immediately before is continued without switching. This reduces frequent switching of the direction in which the driving force is output from the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR, and prevents the behavior of the vehicle from being affected while the heat generation control is being executed.

[0076] In addition, in the second embodiment, when the required driving force Trq falls within the switching limit range SWlim, the magnitude of the driving force of the front motor 2 (i.e., the driving force TF of the front wheels) and the driving force of the rear motor 3 (i.e., the driving force TR of the rear wheels) is limited to fall within the driving force limit range TlimSW. As a result, when the required driving force Trq falls outside the switching limit range SWlim, the direction of outputting the driving force at the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR may be switched. However, since the driving force is limited within the driving force limit range TlimSW, a large switching of the driving force can be prevented, and this can also prevent the behavior of the vehicle from being affected while the vehicle is traveling when the heat generation control is being executed.

[0077] In the second embodiment, the magnitude of the switching limit range SWlim is set to a constant value. However, there is a risk that the required driving force Trq (required deceleration force Tdec) may hunt between the range and the outside of the switching limit range SWlim. Therefore, the ECU 10 may be configured to set the switching limit range SWlim to a first range (for example, a range of 10 Nm to -10 Nm) when the required driving force Trq is larger than the switching limit range SWlim, and to set the switching limit range SWlim to a second range (for example, a range of 20 Nm to -20 Nm) larger than the first range when the required driving force Trq is within the switching limit range SWlim. In short, by providing a difference between the threshold value at which it is determined that the required driving force Trq enters the switching limit range SWlim from outside the range and the threshold value at which it is determined that the required driving force Trq goes out of the range from within the range, it is possible to prevent hunting from occurring even when determining whether the required driving force Trq is within the switching limit range SWlim or outside the range.

[0078] <Possibilities for other embodiments> In the above description of the first and second embodiments, the front motor 2 has been described as the first rotating electric machine and the rear motor 3 as the second rotating electric machine, but the opposite is also possible, that is, the first rotating electric machine is drivingly connected to one of the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR of the vehicle 100, and the second rotating electric machine is drivingly connected to the other of the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR of the vehicle 100. Specifically, the roles of the front motor 2 and the rear motor 3 may be reversed, such as outputting driving force in the vehicle's traveling direction (described in detail later) or switching between power running and regeneration.

[0079] In the first and second embodiments, the heat generation control is described as being executed in all states of the vehicle 100, including stopped, forward traveling, charging, and reverse traveling. However, as long as the heat generation control is executed in some of these states, it is acceptable not to execute the heat generation control in other states. In particular, the heat generation control is described as being executed even during reverse traveling, but since reverse traveling is used less frequently in terms of time than other traveling states, it is acceptable not to execute the heat generation control in the reverse mode.

[0080] In addition, in the first and second embodiments, there are no particular limitations on the size and performance of the front motor 2 and the rear motor 3, but the size and performance of these motors may differ as long as the driving forces can be cancelled out.

[0081] Furthermore, the vehicle 100 described in the first and second embodiments is described as not being equipped with a heater (such as a high-voltage heater) that directly warms the coolant or the battery unit 20, but this is not limiting and does not exclude the inclusion of such a heater. When such a heater is installed, it is conceivable to improve the power consumption by supplying the heater with the electric power regenerated by the front motor 2 during heat generation control during forward driving, or the electric power regenerated by the rear motor 3 during heat generation control during reverse driving.

[0082] Furthermore, in the first and second embodiments, the vehicle 100 has been described as an example of a so-called four-wheel drive electric vehicle in which the front wheels 7FL, 7FR are driven by a front motor 2 and the rear wheels 7RL, 7RR are driven by a rear motor 3. However, the present invention is not limited to this. For example, even if one or both of the front and rear wheels are configured with a hybrid drive device using an engine and a motor (rotating electric machine) as a drive source, the motor of the hybrid drive device can be used as a first rotating electric machine or a second rotating electric machine to output a first cancellation drive force or a second cancellation drive force.

[0083] In addition, in the second embodiment, when the required driving force Trq (required deceleration force Tdec) falls within the switching limit range SWlim, the front wheel driving force TF and the rear wheel driving force TR are limited to be within the driving force limit range TlimSW. However, this is not limited to the above, and the front wheel driving force TF and the rear wheel driving force TR may not be particularly limited, and may be output up to the powering limit driving force TlimP or the regenerative limit driving force TlimR. [Explanation of symbols]

[0084] 1...vehicle drive device / 2...front motor (first rotating electric machine) / 3...rear motor (second rotating electric machine) / 7FL, 7FR...front wheels / 7RL, 7RR...rear wheels / 10...control unit / 100...vehicle / SWlim...switching limit range / Tcan1...first counter driving force / Tcan2...second counter driving force / Trq...request driving force / TlimSW...driving force limit range

Claims

1. a first rotating electric machine drivingly connected to one of the front wheels and the rear wheels of the vehicle; a second rotating electric machine that is driven independently of the first rotating electric machine and is drivingly connected to the other of the front wheels and the rear wheels; a control unit that controls the first rotating electric machine and the second rotating electric machine, The control unit is When performing heat generation control for warming up the vehicle, a first counteracting driving force is controlled to be generated from the first rotating electric machine, and a second counteracting driving force acting on a side opposite to a traveling direction of the vehicle with respect to the first counteracting driving force is controlled to be generated from the second rotating electric machine; When the heat generation control is executed during acceleration of the vehicle, if a required driving force is greater than a switching limit range in an acceleration direction of the vehicle, the first rotating electric machine is regeneratively controlled and the second rotating electric machine is powered; When the heat generation control is executed during deceleration of the vehicle, if a required deceleration force is larger than the switching limit range in a deceleration direction of the vehicle, the first rotating electric machine is powered and the second rotating electric machine is regeneratively controlled; When the heat generation control is executed and the required driving force falls within the switching limit range, the regenerative control or power running control of the first rotating electric machine and the second rotating electric machine in the heat generation control executed immediately before is continued without switching. A drive unit for a vehicle.

2. When the required driving force falls within the switching limit range, the control unit limits the magnitudes of the driving force of the first rotating electric machine and the driving force of the second rotating electric machine to fall within a driving force limit range. The vehicle drive device according to claim 1 .

3. the control unit sets the switching limit range to a first range when the required driving force is greater than the switching limit range, and sets the switching limit range to a second range greater than the first range when the required driving force is within the switching limit range. The vehicle drive device according to claim 1 .

4. the first rotating electric machine is drivingly connected to rear wheels of the vehicle; The second rotating electric machine is drivingly connected to front wheels of the vehicle. The vehicle drive device according to claim 1 .

Images