Vehicle drive device

Abstract

To increase the amount of heat generated during warm-up of a rotary electric machine.SOLUTION: A vehicle drive device 1 comprises a rotary electric machine (2) that is drivingly connected to at least one of front wheels (7FL, 7FR) and rear wheels (7RL, 7RR) of a vehicle (100), and a control unit (10) capable of controlling the rotary electric machine (2) and a brake device (9) of the vehicle (100). When performing heat generation control for warming up the vehicle (100), the control unit (10) performs control such that a canceling driving force (Tcan1) acting in the traveling direction of the vehicle (100) is generated from the rotary electric machine (2), and performs control such that a canceling braking force (Tcan2) acting on the opposite side in the traveling direction with respect to the canceling driving force (Tcan1) is generated from the brake device (9) of the vehicle (100).SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] For example, in a vehicle drive system installed in an electric vehicle, low battery temperatures reduce the efficiency of charging and discharging. This makes charging particularly difficult when the battery is extremely cold (e.g., below 0°C). This, in turn, results in poor fuel economy due to the inability to regenerate power even when the vehicle slows down while traveling. Therefore, for example, when a vehicle is left parked in a low-temperature environment for a long period of time and then driven again, it is necessary to quickly warm up the vehicle. However, warming up an electric vehicle is more difficult than warming up a hybrid vehicle, which is equipped with an internal combustion engine as a heat source. Therefore, a system has been proposed that, while the vehicle is stopped or traveling, pass a d-axis current through the traction motor, separate from the q-axis current that provides driving force, to additionally warm up the traction motor and thereby accelerate battery warm-up (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-165526 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the case of the above-mentioned Patent Document 1, in which a d-axis current is passed through the driving motor to warm it up, the increase in the amount of heat generated by the driving motor is limited, and the warm-up time becomes long, especially in an extremely low temperature environment, making it insufficient for practical use.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a vehicle drive device that can increase the amount of heat generated during warm-up of a rotating electrical machine. [Means for solving the problem]

[0006] One aspect of the present invention is a vehicle drive device that includes a rotating electric machine that is drivingly connected to at least one of the front wheels and rear wheels of a vehicle, and a control unit that can control the rotating electric machine and the vehicle's brake device, wherein when performing heat generation control to warm up the vehicle, the control unit controls the rotating electric machine to generate a counteracting drive force that acts in the vehicle's direction of travel, and controls the vehicle's brake device to generate a counteracting braking force that acts in the opposite direction of travel to the counteracting drive force. [Effects of the Invention]

[0007] According to the present invention, the amount of heat generated during warm-up of a rotating electrical machine can be increased. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing the configuration of a vehicle and a vehicle drive device according to a first embodiment. [Figure 2] 5A and 5B are schematic diagrams showing a state in which heat generation control is executed during acceleration and steady running while the vehicle according to the first embodiment is running forward. [Figure 3] 4 is a schematic diagram showing a state in which heat generation control is executed when the vehicle according to the first embodiment is decelerating while traveling forward. FIG. [Figure 4] 3 is a flowchart showing vehicle travel control according to the first embodiment. [Figure 5] 4 is a flowchart showing vehicle state control according to the first embodiment. [Figure 6] FIG. 10 is a schematic diagram showing the configuration of a vehicle and a vehicle drive device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] First Embodiment A vehicle drive device 1 according to a first embodiment will be described below with reference to FIGS. 1 to 5. FIG.

[0010] [Vehicle configuration] First, the configuration of a vehicle 100 equipped with the vehicle drive device 1 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 front-wheel drive electric vehicle equipped with the vehicle drive device 1, travels forward with the upward direction in the figure, and is equipped with left and right front wheels 7FL, 7FR, left and right rear wheels 7RL, 7RR, a battery unit 20, a so-called front-wheel drive vehicle drive device 1 that drives the front wheels 7FL, 7FR using power from the battery unit 20, a compressor 30 that is a compressor included in an air conditioner 65 that conditions the interior of the vehicle, and the like. In addition, brakes 9, such as disc brakes, are provided on each of the left and right front wheels 7FL, 7FR and the left and right rear wheels 7RL, 7RR.

[0011] The vehicle 100 is also provided with a driver's seat 50, which is shown in a simplified illustration, and the driver's seat 50 is provided with a shift lever 51, an accelerator pedal 52, a brake pedal 53, a steering sensor 54, etc. The vehicle 100 is also provided with a vehicle speed sensor 61, a wheel speed sensor 62, an outside air temperature gauge 63, a battery temperature gauge 64, an air conditioner 65, etc.

[0012] The shift lever 51 is configured to allow the driver to select a shift range, such as parking range, neutral range, drive range, or reverse range, and transmits a signal of the selected shift range to the control unit (ECU) 10, which will be described in detail later.

[0013] 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] Accelerator pedal 52 is configured to be able to detect the accelerator opening and transmits a signal of the accelerator opening to control unit 10. Upon receiving the signal, control unit 10 detects the driver's required driving force Trq based on the accelerator opening. Brake pedal 53 is configured to be able to detect the brake pedal pressure and transmits a signal of the brake pedal pressure to control unit 10. Upon receiving the signal, control unit 10 detects the driver's required deceleration force Tdec based on the brake pedal pressure (amount of depression).

[0015] 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.

[0016] Similarly, in this embodiment, the required deceleration force Tdec is described as being detected from the brake pedal pressure, which is the amount of operation of the brake pedal 53 by the driver, but this is not limited to this, and the required deceleration force Tdec may also be determined by the control unit, for example, by automatic driving, cruise control, etc.

[0017] The steering sensor 54 is configured to detect the steering angle when the driver turns a steering wheel (not shown) in the driver's seat 50. A signal of the steering angle detected by the steering sensor 54 is transmitted to the control unit 10.

[0018] Meanwhile, the vehicle speed sensor 61 is disposed in the drive unit of the front motor 2 (described in detail below) and detects the vehicle speed of the vehicle 100 by detecting the output rotation speed of the front motor 2. The wheel speed sensor 62 is disposed to detect the rotation speed of, for example, the rotor hubs of the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR, thereby detecting the rotation speed of each wheel. The control unit 10 can, for example, determine wheel slippage and calculate the road surface friction coefficient based on the rotation speed of each wheel detected by the wheel speed sensor 62. While the steering angle is detected by the steering sensor 54 as described above, the vehicle's turning angle may be calculated from the difference in rotation speeds of each wheel detected by the wheel speed sensor 62, and this may be used instead of the steering angle. Although the vehicle speed is detected by the vehicle speed sensor 61 as described above, the vehicle speed may also be calculated based on the rotation speed of each wheel detected by the wheel speed sensor 62.

[0019] An outside air thermometer 63 is disposed, for example, near the front grille and detects the temperature of the air outside the vehicle 100. A battery thermometer 64 is disposed near the battery unit 20 and detects the temperature of the battery unit 20. The air conditioner 65 has the compressor 30 that compresses a refrigerant, and exchanges temperature between the coolant circulating through a radiator (not shown), the front motor 2, the battery unit 20, the compressor 30, etc. and the refrigerant compressed by the compressor 30, and uses the temperature of the refrigerant to heat or cool the interior of the vehicle.

[0020] Next, details of the vehicle drive device 1 will be described. The vehicle drive device 1 is configured to include a front motor 2, which is a three-phase brushless DC motor serving as a first rotating electric machine (motor generator) drivingly connected to the front wheels 7FL, 7FR, a drive circuit 5 that can control the drive force (regenerative power) by supplying a drive current (electric power) to the front motor 2, and a control unit (ECU) 10 that can control the drive circuit 5. In other words, the front motor 2 is configured to be able to drive the front wheels 7FL, 7FR to rotate or to regenerate power. In addition, the drive circuit 5 is configured to be able to supply a drive current (electric power) directly to a compressor 30 without going through a battery unit 20.

[0021] 1, the front motor 2 is simply shown as a motor, but is generally configured as a drive unit equipped with a reduction gear mechanism, a differential device, etc. (not shown). In addition, the control unit 10 that performs various controls in this embodiment is described as being provided in the vehicle drive system 1, but may be another control unit provided in the vehicle 100.

[0022] [Vehicle state control] Next, in the first embodiment, state control that is controlled by the control unit 10 of the vehicle drive device 1 and that transitions between modes depending on the state of the vehicle 100 will be described with reference to Fig. 5. Fig. 5 is a flowchart showing the vehicle state control according to the first embodiment. Note that the vehicle state control shown in Fig. 5 is repeatedly executed at predetermined time intervals that depend on the processing speed of the control unit 10, for example, and the state set in each mode transitions as the determination changes.

[0023] 5, for example, when the start switch of the vehicle 100 is turned on, the control unit 10 starts this state control. First, the control unit 10 determines whether the position of the shift lever 51 is in a non-driving range such as the parking range or the neutral range based on a signal from a position detection sensor (not shown) (S11). Next, if the control unit 10 determines that the shift lever 51 is in a non-driving range (YES in S11), it determines whether the vehicle 100 is being charged (S12). For example, if the control unit 10 determines that the vehicle 100 is connected to an external charger, that is, that the vehicle 100 is being charged (YES in S12), it sets the state of the vehicle 100 to the charging mode (S14). If the control unit 10 determines that the vehicle 100 is not being charged (NO in S12), it sets the state of the vehicle 100 to the stop mode (S15).

[0024] On the other hand, when the control unit 10 determines based on the position of the shift lever 51 that the vehicle is not in the non-driving range (NO in S11), it determines based on the position of the shift lever 51 whether the vehicle is in the drive range (forward range) (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). 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 the reverse mode, it can distinguish between a state in which the vehicle 100 is accelerating or steadily traveling based on the required driving force Trq and a state in which the vehicle 100 is decelerating based on the required deceleration force Tdec.

[0025] [Vehicle driving control] Next, in the first embodiment, the driving control of the vehicle 100 controlled by the control unit 10 of the vehicle drive device 1 will be described with reference to Fig. 4. Fig. 4 is a flowchart showing the driving control of the vehicle according to the first embodiment. Note that the driving control of the vehicle shown in Fig. 4 is repeatedly executed at predetermined time intervals according to the processing speed of the control unit 10, for example, when the state of the vehicle 100 is set to forward mode as described above, and the state transitions between a normal driving state and a driving state under heat generation control as the determination of the heat generation request and permission conditions, which will be described in particular in detail later, changes.

[0026] As shown in FIG. 4, when the state of vehicle 100 is set to forward mode as described above, control unit 10 starts vehicle driving control and first determines whether a heat generation request is present (S1). This heat generation request occurs when at least one of the following conditions is met: the outside air temperature detected by outside air thermometer 63 is below a predetermined temperature (e.g., 0°C or below); the air conditioner 65 is turned on for heating and the circulating water temperature is low and therefore does not generate enough heat; or the temperature of battery unit 20 is below a predetermined temperature (e.g., 0°C or below). That is, if control unit 10 determines that warming up (heat generation) is necessary in vehicle 100, it determines that a heat generation request is present; and if it determines that warming up (heat generation) is not necessary, it determines that a heat generation request is not present. Note that the conditions for determining the heat generation request are not limited to these, and may be determined based on other conditions, such as when the temperature inside the vehicle (driver's seat 50) is lower than a predetermined temperature or when the temperature of drive circuit 5 is lower than a predetermined temperature. If the control unit 10 determines that there is no heat generation request (NO in S1), the process proceeds to step S3, and if it determines that there is a heat generation request (YES in S1), the process proceeds to step S2.

[0027] When the process proceeds to step S2, the control unit 10 determines whether or not the conditions for permitting the execution of heat generation control (hereinafter referred to as "permission conditions"), which will be described in detail later, are met. Specifically, the control unit 10 first determines that the permission conditions are not met because one of the permission conditions is whether or not the remaining charge (SOC) of the battery unit 20 is equal to or greater than a predetermined amount (for example, 20% or greater). If the remaining charge is less than the predetermined amount, the remaining charge may be consumed by the heat generation control, making it impossible to drive.

[0028] Furthermore, when the remaining charge is equal to or greater than a predetermined amount, if a parameter that affects the behavior of vehicle 100 while it is traveling is detected, it is determined that the permission condition is not satisfied, and if no such parameter is detected, it is determined that the permission condition is satisfied. Parameters that affect the behavior of vehicle 100 while it is traveling include, for example, a steering angle of equal to or greater than a predetermined angle (e.g., 5 degrees or more) detected by steering sensor 54, a friction coefficient of the road surface that is equal to or less than a predetermined value determined based on detection by wheel speed sensor 62 as described above, a vehicle speed that is equal to or less than a predetermined speed (e.g., 7 km / h or less) determined based on detection by vehicle speed sensor 61, etc.

[0029] That is, when the steering sensor 54 detects a steering angle equal to or greater than a predetermined angle, the vehicle 100 is turning. If an unnecessary driving force from the front motor 2 and a braking force from the brake 9 are generated on each wheel due to heat generation control, which will be described in detail later, the turning performance of the vehicle 100 may be affected. Therefore, it is determined that the permission conditions are not met. Also, when a road friction coefficient equal to or less than a predetermined value is detected, the vehicle 100 is traveling on a road surface with a low friction coefficient, such as a snowy road or a rough road. Similarly, if an unnecessary driving force from the front motor 2 and a braking force from the brake 9 are generated on each wheel due to heat generation control, the behavior of the vehicle 100 may be affected. Therefore, it is determined that the permission conditions are not met. Furthermore, when it is detected that the vehicle speed is equal to or less than a predetermined speed, which means that the vehicle 100 is likely to be stopped or starting, and therefore, if an unintended driving force is generated from the front motor 2, it may affect the ability of the vehicle 100 to stay stopped or cause a shock due to a large change in driving force when starting, it is determined that the permission conditions are not met.

[0030] Furthermore, the control unit determines that the permission condition is not met when the brake depression amount detected by the brake pedal 53 is equal to or greater than a predetermined threshold, i.e., when the required deceleration force is equal to or greater than the predetermined threshold, and determines that the permission condition is met when the brake depression amount detected by the brake pedal 53 is less than the predetermined threshold, i.e., when the required deceleration force is less than the predetermined threshold. In other words, when the brake depression amount detected by the brake pedal 53 is equal to or greater than the predetermined threshold, the driver intends to suddenly decelerate the vehicle 100, and outputting driving force from the front motor 2 through heat generation control may affect the deceleration force of the vehicle 100, so the control unit determines that the permission condition is not met in order to immediately stop the driving force of the front motor 2.

[0031] As described above, if there is no heat generation request (NO in S1) or the permission conditions are not satisfied (NO in S2), the control unit 10 proceeds to step S3 and sets a normal driving state in which heat generation control is not performed. Here, when the accelerator pedal 52 is depressed, the control unit 10 calculates the required driving force Trq based on the accelerator opening detected by the accelerator pedal 52 and the vehicle speed detected by the vehicle speed sensor 61, and calculates the motor driving force of the front motor 2 that achieves the required driving force Trq. Also, when the brake pedal 53 is depressed, the control unit 10 calculates the required deceleration force Tdec based on the brake depression amount detected by the brake pedal 53, and calculates the motor driving force (regenerative force) and brake braking force that achieve the required deceleration force Tdec. Then, the control unit 10 proceeds to step S5, where it controls the front motor 2 (torque control or rotational speed control) to achieve the calculated motor driving force, and also controls the brake 9 (actuation control) to achieve the calculated brake braking force, and returns to step S1.

[0032] On the other hand, if there is a heat generation request (YES in S1) and the permission conditions are met (YES in S2), the control unit 10 proceeds to step S4 and sets a driving state during heat generation control in which heat generation control is performed. Here, when the accelerator pedal 52 is pressed, the control unit 10 calculates the required driving force Trq based on the accelerator opening detected by the accelerator pedal 52 and the vehicle speed detected by the vehicle speed sensor 61. It also calculates a counteracting driving force Tcan1 to be generated by the front motor 2 by executing the heat generation control, and for the front motor 2, calculates the motor driving force of the front motor 2 that achieves the total driving force of these forces. It then calculates a counteracting braking force Tcan2 to be generated by the brake 9 to counteract the counteracting driving force Tcan1 generated by the front motor 2.

[0033] Furthermore, when the brake pedal 53 is depressed, the system calculates the required deceleration force Tdec according to the brake depression amount detected by the brake pedal 53, calculates the brake braking force that achieves the required deceleration force Tdec, and then calculates a counteracting braking force Tcan2 to be generated by the brake 9 by executing heat creation control, and calculates the brake braking force of the brake 9 that achieves the total braking force of these. Then, it calculates a counteracting driving force Tcan1 to be generated by the front motor 2 to counteract the counteracting braking force Tcan2 generated by the brake 9. Note that when the vehicle 100 is decelerating in a traveling state during heat creation control, power is applied to the front motor 2 to generate heat, so regeneration of the front motor 2 is not performed.

[0034] Then, the process proceeds to step S5, where the control unit 10 performs motor control (torque control or rotational speed control) on the front motor 2 so that the motor driving force is the calculated motor driving force, and also performs brake control (operation control) on the brake 9 so that the brake braking force is the calculated brake braking force, and then returns to step S1.

[0035] In the vehicle driving control described above, whether or not a single condition, the heat generation control permission condition, is met is determined based on multiple states (remaining charge, presence or absence of parameters that affect behavior, brake depression amount, etc.), but this is not limiting, and the system may be configured to determine each condition one by one and execute heat generation control when all conditions are met. In other words, the permission condition represents each condition as a single concept, and does not limit the method for determining whether or not to execute heat generation control.

[0036] [Problems with general motor heat generation control] Here, we will explain the problems with general motor heat generation control. The front motor 2 according to the first embodiment is a three-phase brushless DC motor. Generally, when a three-phase brushless DC motor generates heat without outputting torque, a larger-than-normal current is passed through only a single-phase coil while the vehicle is stopped, for example. However, when a large current is passed through a single-phase coil while the vehicle is stopped, if the rotation of the motor changes, for example, due to a slight movement of the vehicle caused by some external factor, the motor may output a large driving force, potentially causing shocks or other problems. Furthermore, when starting the vehicle, a local driving force is generated by the single-phase coil, making it difficult to control the current even when a command is issued to smoothly control the rotation. Furthermore, because the control passes current only through a single-phase coil, the amount of heat generated is small, and if the motor, battery unit, coolant, etc., are extremely low, warming up the motor may take a long time. Therefore, when it is determined that the conditions for permission of heat generation control are met (permission to execute control is determined) as described above and it is decided to execute heat generation control, in the first embodiment, the following heat generation control is executed.

[0037] [Heat generation control] Next, the heat generation control according to the first embodiment will be described. In the heat generation control according to this embodiment, basically, when execution of the heat generation control is permitted during forward travel, the front motor 2 outputs a driving force in the vehicle's traveling direction, and the brake 9 generates a braking force that acts in the opposite direction to the vehicle's traveling direction, and heat is generated by canceling these forces. Generally, the battery unit 20 has the property that it is difficult to charge when it is in a low-temperature state below 0 degrees, but 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 power but not charge it.

[0038] (When accelerating forward and during steady driving) Here, detailed operation of heat generation control during acceleration and steady driving while traveling forward will be described specifically with reference to FIG. 2. FIG. 2 is a schematic diagram showing a state in which heat generation control is executed during acceleration and steady driving while traveling forward of a vehicle according to the first embodiment. Note that during acceleration and steady driving while traveling forward as shown in FIG. 2, the brake pedal 53 is not depressed, and the accelerator pedal 52 is depressed, and the vehicle 100 is accelerating or traveling steadily while traveling forward. This steady driving is a state in which the running resistance of the vehicle 100 and the driving force in the acceleration direction (required driving force Trq) are balanced, and in a broad sense, the operation of the vehicle 100 can be said to be the same as when accelerating. Furthermore, if the running resistance of the vehicle 100 is greater than the driving force in the acceleration direction (required driving force Trq), the vehicle speed of the vehicle 100 will decrease, but in a broad sense, the operation of the vehicle 100 can be said to be the same as when accelerating.

[0039] As described above, when the vehicle is traveling forward and there is a heat generation request (YES in S1) and the conditions for permitting heat generation control are met (YES in S2), the control unit 10 calculates the motor driving force and brake braking force for traveling during heat generation control according to the accelerator opening of the accelerator pedal 52, i.e., the required driving force Trq (S4), and controls the front motor 2 and brake 9 accordingly (S5).

[0040] 2, the control unit 10 controls the front motor 2 to power so that a forward driving force TF, which is the sum of the required driving force Trq and the counteracting driving force Tcan1, is generated at the left and right front wheels 7FL, 7FR, and the control unit 10 also operates the brake 9 so that a counteracting braking force Tcan2, which is a braking force TB (i.e., a deceleration force) equal in magnitude to the counteracting driving force Tcan1 and opposite to the forward direction, is generated at the left and right front wheels 7FL, 7FR and the left and right rear wheels 7RL, 7RR (i.e., four wheels). In other words, the counteracting driving force Tcan1 and the counteracting braking force Tcan2 are canceled out (cancelled), resulting in a traveling state in which the required driving force Trq, which is the difference between the forward driving force TF generated at the front wheels 7FL, 7FR and the braking force TB generated at the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR, is generated as a driving force in the forward direction of the vehicle 100.

[0041] The magnitudes of the counteracting driving force Tcan1 and the counteracting braking force Tcan2 may be set so that the sum of the required driving force Trq and the counteracting driving force Tcan1 is the limit value of the output of the front motor 2 (i.e., so that "output limit value - required driving force = counteracting driving force"). In this case, the limit value of the output of the front motor 2 may be calculated from the remaining battery charge, battery temperature, the temperature of the front motor 2, etc. Also, instead of calculating the counteracting driving force Tcan1 from the limit value of the output of the front motor 2 in this way, it is also possible to set the counteracting driving force Tcan1 to a constant magnitude within a range in which a certain level of required driving force Trq can be output. In any case, the counteracting braking force Tcan2 is set to be equivalent to the counteracting driving force Tcan1.

[0042] As described above, when heat generation control is executed during acceleration during forward travel or steady travel, power is supplied from the battery unit 20 to the front motor 2, but the amount of power supplied to output the counteracting driving force Tcan1 is greater than the amount of power supplied when simply outputting the required driving force Trq during normal travel. As a result, the amount of heat generated in the front motor 2 increases by the amount of counteracting driving force Tcan1 output, shortening the warm-up time of the vehicle 100. Furthermore, warming up the vehicle 100 allows the temperature of the battery unit 20 to quickly reach a temperature at which charging is possible (for example, 0 degrees or higher), and charging becomes possible during subsequent travel by regenerative control of the front motor 2, thereby ultimately improving the power efficiency of the vehicle 100.

[0043] (When decelerating while driving forward) Next, detailed operations when heat generation control is executed during deceleration while traveling forward will be described with reference to Fig. 3. Fig. 3 is a schematic diagram showing a state in which heat generation control is executed during deceleration while traveling forward of the vehicle according to the first embodiment. Note that during deceleration while traveling forward as shown in Fig. 3, accelerator pedal 52 is not depressed, and brake pedal 53 is depressed, and vehicle 100 is decelerating while traveling forward.

[0044] As described above, when the vehicle is traveling forward and there is a heat generation request (YES in S1) and the conditions for permitting heat generation control are met (YES in S2), the control unit 10 calculates the motor driving force and brake braking force for traveling during heat generation control according to the amount of depression of the brake pedal 53, i.e., the required deceleration force Tdec (S4), and controls the front motor 2 and brake 9 accordingly (S5).

[0045] 3, the control unit 10 controls the front motor 2 to operate in a powered manner so that a counteracting driving force Tcan1 is generated on the left and right front wheels 7FL, 7FR as a driving force TF in the forward direction, and the control unit 10 also operates the brake 9 so that a braking force TB (i.e., a deceleration force) in the opposite direction to the forward direction is generated on the left and right front wheels 7FL, 7FR and the left and right rear wheels 7RL, 7RR (i.e., four wheels). In other words, the counteracting driving force Tcan1 and the counteracting braking force Tcan2 are canceled out (cancelled), resulting in a traveling state in which the required deceleration force Tdec, which is the difference between the driving force TF in the forward direction generated on the front wheels 7FL, 7FR and the braking force TB generated on the front wheels 7FL, 7FR and the rear wheels 7RL, 7RR, is generated as a braking force in the opposite direction to the forward direction of the vehicle 100.

[0046] Note that the magnitudes of the counteracting driving force Tcan1 and the counteracting braking force Tcan2 may be set so that the counteracting driving force Tcan1 is equal to the limit value of the output of the front motor 2, because the limit value of the braking force of the brake 9 is generally much greater than the limit value of the output of the front motor 2. In this case, the limit value of the output of the front motor 2 may be calculated from the remaining battery charge, battery temperature, the temperature of the front motor 2, etc. Also, instead of calculating the counteracting driving force Tcan1 from the limit value of the output of the front motor 2 in this way, it is also possible to set the counteracting driving force Tcan1 to a fixed magnitude. In any case, the counteracting braking force Tcan2 is set to be equivalent to the counteracting driving force Tcan1.

[0047] As described above, during normal driving, power is not supplied to the front motor 2, or the front motor 2 is under regenerative control. However, when heat generation control is being executed during deceleration while the vehicle is traveling forward, the battery unit 20 may not be able to charge, and therefore power is supplied to the front motor 2 from the battery unit 20 in an amount corresponding to the output of the counteracting driving force Tcan1. As a result, the amount of heat generated (the amount of heat generated) in the front motor 2 increases by the amount of the output of the counteracting driving force Tcan1, thereby shortening the warm-up time of the vehicle 100. Furthermore, warming up the vehicle 100 allows the temperature of the battery unit 20 to quickly reach a temperature at which charging is possible or higher (for example, 0 degrees or higher), and subsequent driving conditions allow charging by regenerative control of the front motor 2. As a result, the power consumption of the vehicle 100 can be improved.

[0048] [Summary of the first embodiment] As described above, in the vehicle drive system 1 according to the first embodiment, when the control unit 10 executes heat generation control to warm up the vehicle 100 (i.e., when there is a heat generation request), it performs powering control so that the front motor 2 generates a counteracting driving force Tcan1 acting in the traveling direction of the vehicle 100, and also controls so that the brakes 9 of the vehicle 100 generate a counteracting braking force Tcna2 acting in the opposite direction to the traveling direction of the counteracting driving force Tcan1. As a result, when the vehicle 100 is warming up, the amount of heat generated (amount of heat generated) in the front motor 2 can be increased by the amount of the counteracting driving force Tcan1 output, and the warm-up time of the vehicle 100 can be shortened.

[0049] The control unit 10 also determines whether the permission conditions are met (S2), and if the permission conditions are met (YES in S2), executes the heat creation control (S4, S5). This allows the heat creation control to be executed without affecting the running of the vehicle 100.

[0050] In particular, when the required deceleration force Tdec becomes equal to or exceeds a threshold value, for example, when the driver brakes suddenly, the control unit 10 determines that the permission conditions are not met (NO in S2), thereby stopping the heat generation control, and preventing the cancellation driving force Tcan1 of the front motor 2 from affecting the sudden deceleration of the vehicle 100.

[0051] In addition, when the remaining charge of the battery unit 20 is less than a predetermined amount, for example, the control unit 10 determines that the permission conditions are not met (NO in S2), thereby preventing the remaining charge from being consumed by heat generation control.

[0052] In addition, when the control unit 10 detects a parameter that affects the behavior of the vehicle 100 while it is traveling, it can stop the heat generation control by determining that the permission conditions are not met (NO in S2), thereby preventing the execution of the heat generation control from affecting the behavior of the vehicle 100 while it is traveling.

[0053] Specifically, for example, if the steering sensor 54 detects a steering angle greater than a predetermined angle as the above parameter, it is possible to stop the heat generation control by determining that the permission conditions are not met, thereby preventing any impact on the cornering performance of the vehicle 100.

[0054] Furthermore, for example, if a road surface friction coefficient below a predetermined value is detected as the above parameter based on detection by wheel speed sensor 62, it is possible to stop heat generation control by determining that the permission conditions are not met, thereby preventing any impact on the behavior of vehicle 100 while driving.

[0055] Furthermore, for example, if the vehicle speed is detected as a parameter based on detection by the vehicle speed sensor 61 to be below a predetermined speed, the heat generation control can be stopped by determining that the permission conditions are not met, thereby preventing an impact on maintaining the vehicle 100 at a standstill or a shock due to a large change in driving force when starting.

[0056] Second Embodiment Next, a second embodiment, which is a partial modification of the first embodiment, will be described with reference to Fig. 6. Fig. 6 is a schematic diagram showing the configuration of a vehicle and a vehicle drive device according to the second embodiment.

[0057] Compared to the vehicle driving device 1 in the vehicle 100 according to the first embodiment, the vehicle driving device 1 in the vehicle 200 according to the second embodiment includes a rear motor 3 drivingly connected to the left and right rear wheels 7RL, 7RR instead of the front motor 2. In other words, the vehicle driving device 1 of the vehicle 200 is a so-called rear-wheel drive vehicle driving device that drives the rear wheels 7RL, 7RR using electric power from the battery unit 20.

[0058] In the vehicle drive device 1 of the vehicle 200 configured in this manner, when heat generation control is executed, a counteracting driving force Tcan1 acting in the direction of travel of the vehicle 100 is generated at the rear wheels 7RL, 7RR by powering control of the rear motor 3, and a counteracting braking force Tcan2 is generated by the brake 9, thereby increasing the amount of heat generated by the rear motor 3 as in the first embodiment.

[0059] Other than this, the configuration, operation, and effects of the second embodiment are the same as those of the first embodiment, and therefore a description thereof will be omitted.

[0060] <Possibilities for other embodiments> In the first embodiment described above, a vehicle drive system including a front motor 2 that drives the front wheels 7FL, 7FR has been described, and in the second embodiment, a vehicle drive system including a rear motor 3 that drives the rear wheels 7RL, 7RR has been described, but the present invention is not limited to these, and the vehicle drive system 1 may be a so-called four-wheel drive vehicle drive system including a front motor 2 and a rear motor 3, that is, a system including a rotating electric machine that is drivingly connected to at least one of the front wheels and the rear wheels. When the front motor 2 and the rear motor 3 are provided, it is conceivable to power-control the front motor 2 and the rear motor 3 to output a counteracting drive force Tcan1 while operating the brake 9 to generate a counteracting braking force Tcan2.

[0061] In addition, the first embodiment has been described as including a front motor 2 that drives the front wheels 7FL, 7FR, and the second embodiment has been described as including a rear motor 3 that drives the rear wheels 7RL, 7RR, but this is not limiting. For example, one or both of the front and rear wheels may be configured as a hybrid drive system using an engine and a motor (rotating electric machine) as a drive source. In this case, the motor of the hybrid drive system may be configured to output the cancellation drive force Tcan1 using the motor as a rotating electric machine.

[0062] Furthermore, in the first and second embodiments, the heat generation control is executed when the vehicle 100 or the vehicle 200 is traveling forward, and in particular, the execution of the heat generation control is not permitted at vehicle speeds below a predetermined speed, but this is not limiting, and the heat generation control may also be executed when the vehicle is traveling backward or when stopped (including when charging). In particular, when the heat generation control is executed while the vehicle is stopped, it is conceivable to not permit the execution of the heat generation control when the vehicle starts moving, and to resume the execution of the heat generation control when the vehicle speed reaches a predetermined speed or above.

[0063] Furthermore, in the first and second embodiments, the counteracting driving force Tcan1 to be generated by the front motor 2 or the rear motor 3 is calculated, and then the counteracting braking force Tcan2 to be generated by the brake 9 is calculated accordingly. However, this is not limiting, and it is also possible to first calculate the counteracting braking force Tcan2 to be generated by the brake 9, and then calculate the counteracting driving force Tcan1 to be generated by the front motor 2 or the rear motor 3 accordingly. In this case, it is conceivable to set the counteracting braking force Tcan2 to a constant value that can be sufficiently counteracted by the front motor 2 or the rear motor 3.

[0064] Furthermore, the vehicle 100 or the vehicle 200 described in the first and second embodiments may or may not be provided with a heater (such as a high-voltage heater) that directly heats the coolant or the battery unit 20. [Explanation of symbols]

[0065] 1... Vehicle drive device / 2... Front motor (rotating electric machine) / 3... Rear motor (rotating electric machine) / 7FL, 7FR... Front wheels / 7RL, 7RR... Rear wheels / 9... Brake (brake device) / 10... Control unit / 100... Vehicle / 200... Vehicle / Tcan1... Cancellation driving force / Tcan2... Cancellation braking force / Tdec... Required deceleration force

Claims

1. a rotating electric machine drivingly connected to at least one of the front wheels and the rear wheels of the vehicle; a control unit capable of controlling the rotating electric machine and a brake device of the vehicle, When executing heat generation control to warm up the vehicle, the control unit controls the rotating electric machine to generate a counteracting driving force acting in the traveling direction of the vehicle, and controls the vehicle brake device to generate a counteracting braking force acting in the opposite direction of the traveling direction to the counteracting driving force. Vehicle drive unit.

2. The control unit determines whether a permission condition is satisfied, and executes the heat generation control when the permission condition is satisfied. The vehicle drive system according to claim 1 .

3. The control unit determines that the permission condition is not satisfied when the required deceleration force is equal to or greater than a threshold, and determines that the permission condition is satisfied when the required deceleration force is not equal to or greater than the threshold. The vehicle drive system according to claim 2 .

4. the control unit determines that the permission condition is not satisfied when a parameter that affects the behavior of the vehicle while it is traveling is detected, and determines that the permission condition is satisfied when the parameter is not detected. The vehicle drive system according to claim 2 .

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