Control method for electric vehicles, and control device for electric vehicles

Abstract

To provide a control method of an electric vehicle and a control device of an electric vehicle that allow regenerative brake force to be efficiently set.SOLUTION: There is provided a control method of an electric vehicle, in which the electric vehicle comprises: a first drive motor which includes a motor body, and a drive motor accommodating first oil for cooling the motor body, and in which the drive motor transfers drive power to driving wheels on a front side of the vehicle; and a second drive motor for transferring drive power to second driving wheels disposed on a rear side of the vehicle. Further, the electric vehicle distributes, to the first drive motor, all requested drive power requested by a driver when starting up the vehicle. In the control method of the electric vehicle, when a temperature of the first oil at start-up of a vehicle is lower than a predetermined temperature, brake force of the second drive motor is set to a prescribed regenerative brake force, the drive power of the first drive motor is set to an aggregated drive power obtained by summing a setoff drive power cancelling the regenerative brake force, and the requested drive power, and a magnitude of the regenerative brake force is set to a half or less of the magnitude of the requested drive power.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a control method for an electric vehicle and a control device for an electric vehicle.

Background Art

[0002] Patent Document 1 discloses that in a vehicle having two or more axles and a pair of drive motors, one or more axles are drivingly coupled to one of the drive motors, and the other one or more axles are drivingly coupled to the other drive motor. When performing a warm-up operation, a required driving force requested by a driver is output to one of the pair of drive motors, and a regenerative braking force is output to the other.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in Patent Document 1, when the required driving force is small and there is a margin in the maximum driving force of the drive motor, an appropriate amount of regenerative braking force is calculated within the margin, but a specific calculation method is not disclosed, and the regenerative braking force cannot be determined efficiently.

[0005] An object of the present invention is to provide a control method for an electric vehicle and a control device for an electric vehicle that can efficiently determine a regenerative braking force.

Means for Solving the Problems

[0006] The electric vehicle control method according to the present invention includes a motor body for driving a motor shaft, a motor case housing the motor body, a drive motor in which a first oil for cooling the motor body is contained within the motor case, a drive shaft for supporting a drive wheel, a gear mechanism for engaging the motor shaft and the gear mechanism by gear coupling, and a gear case housing the gear mechanism, and a gearbox in which a second oil for cooling the gear mechanism is contained within the gear case. The drive motor includes a first drive motor for transmitting driving force to a first drive wheel located on one of the drive wheels in the longitudinal direction of the vehicle, and a second drive motor for transmitting driving force to a second drive wheel located on the other of the drive wheels in the longitudinal direction of the vehicle. The gearbox includes a first gearbox for transmitting the driving force of the first drive motor to the first drive wheel, and a second gearbox for transmitting the driving force of the second drive motor to the second drive wheel. The electric vehicle control method distributes all the requested driving force requested by the driver to the first drive motor when the vehicle is started. This control method, when the temperature of the first or second oil is below a predetermined temperature at vehicle startup, sets the output state of the first drive motor to the powering state and the output state of the second drive motor to the regenerative state, sets the braking force of the second drive motor to a predetermined regenerative braking force, and sets the driving force of the first drive motor to a combined driving force which is the sum of the offsetting driving force that cancels out the regenerative braking force and the required driving force. Then, sets the magnitude of the regenerative braking force to half or less of the magnitude of the required driving force. [Effects of the Invention]

[0007] According to the present invention, the first and second oils can be warmed up and the battery charged without interfering with the vehicle's operation, and the regenerative braking force can be efficiently determined in relation to the required driving force. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram of a vehicle to which the electric vehicle control method (control device) of this embodiment is applied. [Figure 2] Figure 2 shows the changes in the output state of the first and second drive motors. [Figure 3]Figure 3 is a schematic cross-sectional view of the drive motor and gearbox. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the attached drawings.

[0010] [Vehicle 100 configuration] Figure 1 is a block diagram illustrating the configuration of a vehicle 100 to which the electric vehicle control method (control device) of this embodiment is applied. Vehicle 100 is an electric vehicle. An electric vehicle is a vehicle that is equipped with drive motors 4 (front drive motor 4f, rear drive motor 4r) as a drive source and runs by generating a driving force at the front wheels 9f and rear wheels 9r due to the torque generated by the drive motors 4.

[0011] As shown in Figure 1, the vehicle 100 comprises a front drive system FDS, a rear drive system RDS, a battery 1, and a controller 2 (control unit).

[0012] The front drive system fds receives power from battery 1 and drives the front wheels 9f under the control of controller 2. The front drive system fds includes a front inverter 3f, a front drive motor 4f, a front gearbox 5f, a front rotation sensor 6f, a front drive shaft 8f, and front wheels 9f. The subscript f indicates that it is a front-side component. The front wheels 9f are a pair of drive wheels 9 that are relatively in the forward direction of the vehicle 100, out of the four drive wheels 9 that the vehicle 100 has. The forward direction of the vehicle 100 is a predetermined direction formally determined according to the orientation of the driver's seat, etc. With the front drive system fds, the front wheels 9f function as drive wheels 9 that generate the driving force of the vehicle 100.

[0013] The rear drive system (rds) receives power from the battery (1) and drives the rear wheels (9r) under the control of the controller (2). The rear drive system (rds), symmetrically to the front drive system (fds), comprises a rear inverter (3r), a rear drive motor (4r), a rear gearbox (5r), a rear rotation sensor (6r), a rear drive shaft (8r), and rear wheels (9r). The subscript 'r' indicates that it is a rear component. The rear wheels (9r) are a pair of drive wheels (9) located relatively towards the rear of the vehicle (100) among the four drive wheels (9) of the vehicle (100). "Rearward" refers to the direction opposite to the forward direction of the vehicle (100). The rear drive system (rds) causes the rear wheels (9r) to function as drive wheels (9) that generate the driving force for the vehicle (100).

[0014] Battery 1 is connected to the drive motor 4 via inverter 3 and supplies drive power to the drive motor 4 by discharging. Battery 1 can also be charged by receiving regenerative power from the drive motor 4. In the front drive system fds, battery 1 is connected to the front drive motor 4f via front inverter 3f. Similarly, in the rear drive system rds, battery 1 is connected to the rear drive motor 4r via rear inverter 3r.

[0015] Controller 2 is a control device for vehicle 100 and is a computer composed of a central processing unit (CPU), read-only memory (ROM), random access memory (RAM), input / output interface (I / O interface), etc. Controller 2 generates control signals to control the front drive motor 4f and rear drive motor 4r based on vehicle variables of vehicle 100. Vehicle variables are information that indicates the operating state or control state of the vehicle 100 as a whole or each part that constitutes the vehicle 100, and can be obtained by detection, measurement, or calculation, etc. Vehicle variables include, for example, accelerator opening APO, longitudinal G and lateral G, vehicle speed V, gradient value, steering angle, wheel speed, as well as the rotational speed Nmf of the front drive motor 4f, the rotational speed Nmr of the rear drive motor 4r, and three-phase AC current. Controller 2 uses these vehicle variables to control the front drive motor 4f and rear drive motor 4r, respectively.

[0016] The front inverter 3f converts the DC current supplied from the battery 1 into AC current by switching its switching element on and off in response to the drive signal generated by the controller 2, and adjusts the current supplied to the front drive motor 4f. Similarly, the rear inverter 3r converts the DC current supplied from the battery 1 into AC current by switching its switching element on and off in response to the drive signal generated by the controller 2, and adjusts the current supplied to the rear drive motor 4r. In addition, the front inverter 3f reverses the AC current generated by the front drive motor 4f due to regenerative braking into DC current and adjusts the current supplied to the battery 1. Similarly, the rear inverter 3r reverses the AC current generated by the rear drive motor 4r due to regenerative braking into DC current and adjusts the current supplied to the battery 1.

[0017] The front drive motor 4f (first drive motor) and the rear drive motor 4r (second drive motor) are, for example, three-phase AC motors, and generate driving force (torque T) by AC current supplied from the connected inverter 3. The driving force generated by the front drive motor 4f is transmitted to the front wheels 9f via the front gearbox 5f and the front drive shaft 8f. Similarly, the driving force generated by the rear drive motor 4r is transmitted to the rear wheels 9r via the rear gearbox 5r and the rear drive shaft 8r. When the front drive motor 4f and the rear drive motor 4r rotate together with the front wheels 9f and the rear wheels 9r, respectively, they generate regenerative braking force and recover the kinetic energy of the vehicle 100 as electrical energy.

[0018] The gearbox 5 (front gearbox 5f, rear gearbox 5r) is composed of multiple gears and includes a reduction gear 52 (Figure 3) that reduces the rotational speed Nm of the drive motor 4 and transmits it to the drive shaft 8, and a differential gear 53 (Figure 3) that creates a difference in the rotational speed of the left and right drive wheels 9 when the vehicle 100 is steered.

[0019] As described later, the front drive motor 4f and the front gearbox 5f are formed as a single unit, and the rear drive motor 4r and the rear gearbox 5r are formed as a single unit (see Figure 3).

[0020] The front rotation sensor 6f and the rear rotation sensor 6r detect the rotor phase of the drive motor 4 to which each is connected, and output the detected phase to the controller 2. Based on the output of the front rotation sensor 6f, the controller 2 detects the rotational speed Nmf of the front drive motor 4f, and based on the output of the rear rotation sensor 6r, the controller 2 detects the rotational speed Nmr of the rear drive motor 4r. The front current sensor 7f and the rear current sensor 7r detect the current flowing through the drive motor 4 to which each is connected, and output the detected current to the controller 2. In the present embodiment, the front current sensor 7f detects the three-phase alternating current of the front drive motor 4f, and the rear current sensor 7r detects the three-phase alternating current of the rear drive motor 4r.

[0021] In addition to the front rotation sensor 6f, the front current sensor 7f, the rear rotation sensor 6r, and the rear current sensor 7r described above, the vehicle 100 includes various sensors 15. The various sensors 15 include, for example, an accelerator opening sensor 15a, a temperature sensor 15b, an acceleration sensor 15c, and a steering angle sensor 15d. The accelerator opening sensor 15a detects the accelerator opening APO, which is the operation amount of the accelerator pedal. The temperature sensor 15b is constituted by, for example, a thermistor, and detects any one of the temperature of the first oil 46 (Fig. 3) circulating in the front drive motor 4f (or the rear drive motor 4r), the temperature of the second oil 55 (Fig. 3) circulating in the front gearbox 5f (or the rear gearbox 5r), and the outside air temperature. The acceleration sensor 15c detects the acceleration of the vehicle 100 in the longitudinal and lateral directions, that is, the longitudinal G and the lateral G. The steering angle sensor 15d detects the steering angle of the steering wheel. As other various sensors 15, a brake sensor, a gradient sensor, and a vehicle speed sensor are provided. The brake sensor detects the presence or absence of the operation of the brake pedal. The vehicle speed sensor detects the vehicle speed V of the vehicle 100. The vehicle speed V is the moving speed of the entire vehicle body of the vehicle 100, that is, the vehicle body speed. The gradient sensor detects the gradient value, which is the gradient of the traveling road of the vehicle 100. The detection values detected by the various sensors 15 are input to the controller 2.

[0022] The controller 2 distributes the required driving force (the product of the required torque and the rotational speed) required by the driver to the front drive motor 4f and the rear drive motor 4r based on the vehicle variables of the vehicle 100. However, when the vehicle 100 starts and runs immediately after startup, the controller 2 distributes all of the required driving force to the first drive motor (front drive motor 4f).

[0023] At this time, the second drive motor (rear drive motor 4r) to which the required driving force is not distributed is in a state of being carried along by the first drive motor (front drive motor 4f). Alternatively, the controller 2 sets the second drive motor (rear drive motor 4r) to a driving state having an auxiliary driving force (auxiliary torque × rotational speed) for canceling the friction torque of the second drive motor (rear drive motor 4r).

[0024] Here, the first drive motor is the front drive motor 4f and the second drive motor is the rear drive motor 4r, but the first drive motor may be the rear drive motor 4r and the second drive motor may be the front drive motor 4f.

[0025] When the temperature detected by the temperature sensor 15b is lower than a predetermined temperature (for example, -20 [°C]) immediately after the vehicle 100 starts, the controller 2 sets the output state of the second drive motor (rear drive motor 4r) to a regenerative state having a predetermined regenerative braking force (regenerative torque × rotational speed), and sets the output state of the first drive motor (front drive motor 4f) to a power running state having a combined driving force obtained by adding together the canceling driving force for canceling the regenerative braking force and the required driving force.

[0026] Here, the predetermined temperature is the lower limit temperature at which the viscosity of the first oil 46 or the second oil 55 is maintained at a level that does not affect the driving of the drive motor 4 and the gearbox 5, and it is desirable to obtain this experimentally from the oil quantity and oil performance.

[0027] The vehicle 100 is driven by the combined force of the first drive motor (front drive motor 4f) and the second drive motor (rear drive motor 4r), that is, the required driving force.

[0028] At this time, the first drive motor (front drive motor 4f) and inverter 3 (front inverter 3f) consume energy based on the combined driving force, and the heat generated can heat the first oil 46 and the second oil 55 on the first drive motor side.

[0029] The second drive motor (rear drive motor 4r) and inverter 3 (rear inverter 3r) charge the battery 1 with regenerative power based on regenerative braking force, and the heat from the regenerative power can heat the first oil 46 and second oil 55 on the second drive motor side.

[0030] When the drive motor 4 is in operation, the temperature of the gearbox 5 becomes higher than the temperature of the drive motor 4, so heat is transferred from the gearbox 5 (second oil 55) to the drive motor 4 (first oil 46). As the first oil 46 and the second oil 55 are heated, their viscosity decreases, which reduces the friction torque in the drive motor 4 and the gearbox 5.

[0031] Controller 2 sets the magnitude of the regenerative braking force to a value greater than zero and less than or equal to half the magnitude of the required driving force. This allows the warming of the first oil 46 and the second oil 55 and the charging of the battery 1 to be performed without interfering with the driving of the vehicle 100, and the regenerative braking force to be efficiently determined in relation to the required driving force. For example, if the power consumption related to the required driving force is 20 [kW], the power consumption related to the regenerative braking force will be 10 [kW]. Therefore, the temperature of the drive motor 4 (gearbox 5) in the powering state rises faster than that of the drive motor 4 (gearbox 5) in the regenerative state.

[0032] Here, the regenerative torque and rotational speed of the second drive motor (first drive motor) when generating regenerative braking force are set such that, in a coordinate space with the torque and rotational speed of the second drive motor (first drive motor) as coordinate axes, the operating point represented by the rotational speed and regenerative torque of the second drive motor (first drive motor) coincides with the optimal operating line that represents the relationship (trajectory) between rotational speed and torque when the operating efficiency of the second drive motor (first drive motor) is maximized (power consumption is minimized). As a result, when the power consumption related to regenerative braking force is 10 [kW], approximately 5 [kW] of power can be supplied to battery 1.

[0033] When the acceleration (forward / backward G) detected by the acceleration sensor 15c decreases to a predetermined value (when the vehicle speed becomes nearly constant), the controller 2 gradually changes the output state of the first drive motor (front drive motor 4f) from a powering state related to the combined driving force to a regenerative state related to regenerative braking force.

[0034] At this time, the controller 2 gradually changes the output state of the second drive motor (rear drive motor 4r) from a regenerative state related to regenerative braking force to a traction state related to the combined drive force, so as to maintain a state in which the combined force of the first drive motor (front drive motor 4f) and the second drive motor (rear) becomes the required driving force.

[0035] Furthermore, if the acceleration sensor 15c detects an acceleration (lateral G) exceeding a predetermined value, or if the steering angle sensor 15d detects a steering angle exceeding a predetermined value, i.e., if the vehicle 100 begins to turn (travel on a curve, turn right, turn left), the controller 2 will not perform the above-mentioned change in output state.

[0036] Furthermore, if the vehicle 100 starts turning while the controller 2 is performing the above-mentioned change in output state, the controller 2 stops the above-mentioned change in output state and maintains the output state at the time of stopping. Then, when the acceleration (lateral G) detected by the acceleration sensor 15c falls below a predetermined value, and the steering angle detected by the steering angle sensor 15d falls below a predetermined value, that is, when the vehicle 100 has finished turning and is traveling in a nearly straight line, the controller 2 resumes changing the output state.

[0037] By changing the output state as described above, the second drive motor (rear drive motor 4r) and inverter 3 (rear inverter 3r) consume energy based on the combined driving force, and the resulting heat can heat the first oil 46 and second oil 55 on the second drive motor side.

[0038] The first drive motor (front drive motor 4f) and inverter 3 (front inverter 3f) charge the battery 1 with regenerative power based on regenerative braking force, and the heat from the regenerative power can heat the first oil 46 and the second oil 55 on the first drive motor (front drive motor 4f) side.

[0039] Furthermore, in conditions where the road surface on which the vehicle 100 is traveling is frozen or otherwise has low road surface friction (μ), the first drive motor (front drive motor 4f) and the second drive motor (rear drive motor 4r) are set to the powered state in order to prioritize drivability, and the required driving force is appropriately distributed to the first drive motor (front drive motor 4f) and the second drive motor (rear drive motor 4r) based on the vehicle variables of the vehicle 100.

[0040] [Changes in output status] Figure 2 shows the changes in the output state of the first and second drive motors. The output state of the first and second drive motors changes in the order shown in Figure 2(A) (initial state) to Figure 2(F).

[0041] As shown in Figure 2(A), in the initial state, the first drive motor is in the powering state, and its driving force is the sum of the required driving force and a predetermined offsetting driving force. The second drive motor is in the regenerative state, and its braking force is a predetermined regenerative braking force. The magnitude of the regenerative braking force is less than half the magnitude of the required driving force, and the magnitude of the offsetting driving force is equal to the magnitude of the regenerative braking force.

[0042] As shown in Figure 2(B), the counteracting driving force of the first drive motor and the regenerative braking force of the second drive motor gradually decrease at the same rate.

[0043] As shown in Figure 2(C), the offsetting drive force of the first drive motor and the regenerative braking force of the second drive motor become zero simultaneously.

[0044] As shown in Figure 2(D), the required driving force of the first drive motor gradually decreases, and the second drive motor switches from a regenerative state to a powered state, and its driving force gradually increases to the amount of the decrease in the required driving force of the first drive motor.

[0045] As shown in Figure 2(E), the driving force of the first drive motor becomes zero, and the driving force of the second drive motor becomes the required driving force.

[0046] As shown in Figure 2(F), the first drive motor transitions from a powered state to a regenerative state, and its braking force gradually increases until it reaches a predetermined regenerative braking force. Meanwhile, the driving force of the second drive motor increases at the same rate as the braking force increasing in the first drive motor, and the combined driving force is the sum of the offsetting driving force that cancels out the regenerative driving force generated by the first drive motor and the required driving force.

[0047] Even when the output state changes as shown in Figures 2(A) to 2(F) above, the combined force of the first and second drive motors remains constant, maintaining the required driving force.

[0048] Subsequently, although not shown in the diagram, controller 2 changes the output states of the first drive motor and the second drive motor in the reverse order of Figures 2(A) to 2(F), and finally returns them to their original state (initial state).

[0049] [Drive motor 4 and gearbox 5] Figure 3 is a schematic cross-sectional view of the drive motor 4 and gearbox 5. As shown in Figure 3, in the vehicle 100, the inverter 3 (front inverter 3f), drive motor 4 (front drive motor 4f), and gearbox 5 (front gearbox 5f) are integrally formed. Similarly, the inverter 3 (rear inverter 3r), drive motor 4 (rear drive motor 4r), and gearbox 5 (rear gearbox 5r) are integrally formed.

[0050] The inverter 3 consists of an inverter case 31 and an inverter body 32.

[0051] The drive motor 4 consists of a motor case 41, a motor body (stator 42, rotor core 43, rotor shaft 44), and a first oil pan 45.

[0052] The gearbox 5 consists of a gear case 51, a gear mechanism (reduction gear 52, differential gear 53), and a second oil pan 54.

[0053] The inverter case 31, motor case 41, and gear case 51 are integrated into a single unit. A partition wall 47 separates the motor case 41 and the gear case 51. Each case is formed from aluminum die-cast, which has good thermal conductivity.

[0054] The drive shaft 8 (drive shaft 81, drive shaft 82), rotor shaft 44, reduction gear 52, and differential gear 53 are supported by bearings located in each case.

[0055] In the motor case 41, the stator 42, rotor core 43, rotor shaft 44 (motor shaft), and drive shafts 8 (drive shafts 81 and 82) are arranged coaxially.

[0056] The rotor shaft 44 has a hollow structure, and the drive shaft 8 is inserted through its interior. The rotor shaft 44 also protrudes into the gear case 51 and is gear-coupled to the reduction gear 52.

[0057] The reduction gear 52 reduces the driving force of the rotor shaft 44 by a predetermined reduction ratio and transmits it to the differential gear 53. The differential gear 53 transmits the driving force transmitted from the reduction gear 52 to the drive shafts 8 (drive shafts 81 and 82). Furthermore, when the vehicle 100 turns, based on the difference obtained by subtracting the load from the inner drive wheel 9 from the load from the outer drive wheel 9, the differential gear 53 operates such that, for example, the rotational speed of the drive shaft 81 supporting the outer drive wheel 9 becomes higher than the rotational speed of the drive shaft 82 supporting the inner drive wheel 9, corresponding to that difference.

[0058] The first oil pan 45 is located at the bottom of the motor case 41. The first oil pan 45 stores the first oil 46. Although not shown in the diagram, a circulation pump (circulation mechanism) is located inside the motor case to circulate the first oil 46 to the motor body (stator 42, rotor core 43, rotor shaft 44). The circulation pump draws up the first oil 46 stored in the first oil pan 45 and supplies it to the motor body. The first oil 46 supplied to the motor body cools the motor body and then returns to the first oil pan 45.

[0059] The second oil pan 54 is located at the bottom of the gear case 51. The second oil pan 54 stores the second oil 55. The second oil 55 is stored in the second oil pan 54 such that its liquid level is higher than, for example, the bottom of the reduction gear 52 (gear). As a result, when the reduction gear 52 rotates, the reduction gear 52 (gear tooth surface) scrapes up the second oil 55, which is then supplied to the gear mechanism (reduction gear 52, differential gear 53) to cool the gear mechanism, and then returns to the second oil pan 54. In Figure 3, the reduction gear 52 is positioned to be in contact with the second oil 55 stored in the second oil pan 54, but the differential gear 53 may be positioned to be in contact with the second oil 55 stored in the second oil pan 54.

[0060] As shown in Figure 3, the first oil pan 45 and the second oil pan 54 are arranged so as to sandwich the partition wall 47.

[0061] The first oil pan 45 is formed such that the surface of the partition wall 47 facing the motor case 41 is part of the inner wall of the first oil pan 45.

[0062] The second oil pan 54 is formed such that the side of the partition wall 47 opposite to the first oil pan 45 (the side facing the gear case 51) becomes part of the inner wall of the second oil pan 54.

[0063] Furthermore, the first oil 46 stored in the first oil pan 45 and the second oil 55 stored in the second oil pan 54 are stored in such a way that they overlap each other in the height direction.

[0064] As a result, the first oil 46 and the second oil 55 are arranged facing each other with a partition wall 47 in between, allowing for efficient heat exchange between the first oil 46 and the second oil 55. In particular, when heating the first oil 46 and the second oil 55, the heat from the second oil 55 heated by the gear mechanism (reduction gear 52, differential gear 53) can be efficiently transferred to the first oil 46, allowing the first oil 46 to be heated in a short time and reducing the friction torque of the drive motor 4 and gearbox 5 in a short time. Conversely, if the temperature of the motor body is higher than that of the gear mechanism, the heat from the first oil 46 heated by the motor body (stator 42, rotor core 43, rotor shaft 44) can be efficiently transferred to the second oil 55, allowing the second oil 55 to be heated in a short time and reducing the friction torque of the drive motor 4 and gearbox 5 in a short time.

[0065] [Effects of this embodiment] According to the electric vehicle control method of this embodiment, the motor body (stator 42, rotor core 43, rotor shaft 44) that drives the motor shaft (rotor shaft 44), the motor case 41 that houses the motor body, the drive motor 4 in which a first oil 46 for cooling the motor body is housed in the motor case 41, the drive shaft 8 that pivotally supports the drive wheel 9, the motor shaft (rotor shaft 44), the gear mechanism (reduction gear 52, differential gear 53) that engages these components by gear coupling, and the gear case that houses the gear mechanism The gearbox 5 includes a gear case 51 containing a second oil 55 for cooling the gear mechanism, and the drive motor 4 includes a first drive motor (e.g., front drive motor 4f) for transmitting driving force to a first drive wheel (e.g., front wheel 9f) located on one side of the vehicle 100 in the longitudinal direction (e.g., the front) of the drive wheels 9, and a second drive motor (rear drive motor 4r) for transmitting driving force to a second drive wheel (rear wheel 9r) located on the other side of the vehicle 100 in the longitudinal direction (e.g., the rear) of the drive wheels 9, and Abox 5 includes a first gearbox (front gearbox 5f) that transmits the driving force of the first drive motor (front drive motor 4f) to the first drive wheel (front wheel 9f), and a second gearbox (rear gearbox 5r) that transmits the driving force of the second drive motor (rear drive motor 4r) to the second drive wheel (rear wheel 9r), and is an electric vehicle control method that distributes all the requested driving force requested by the driver to the first drive motor (front drive motor 4f) when the vehicle 100 is started, and when the vehicle 100 is started, the first oil 46 or the 2 When the temperature of oil 55 is lower than a predetermined temperature, the output state of the first drive motor (front drive motor 4f) is set to the powering state and the output state of the second drive motor (rear drive motor 4r) is set to the regenerative state, the braking force of the second drive motor (rear drive motor 4r) is set to a predetermined regenerative braking force, the driving force of the first drive motor (front drive motor 4f) is set to a combined driving force which is the sum of the offsetting driving force that cancels out the regenerative braking force and the required driving force, and the magnitude of the regenerative braking force is set to half or less of the magnitude of the required driving force.

[0066] By the above method, the first oil 46 and second oil 55 that cool the first drive motor (front drive motor 4f) can be warmed up by the heat generated when the first drive motor (front drive motor 4f) outputs the combined driving force, and the first oil 46 and second oil 55 that cool the second drive motor (rear drive motor 4r) can be warmed up by the heat generated when the second drive motor (rear drive motor 4r) outputs the regenerative braking force. Furthermore, the warming up of the first oil 46 and second oil 55 and charging of the battery 1 can be performed without interfering with the driving of the vehicle 100, and the regenerative braking force can be efficiently determined in relation to the required driving force.

[0067] In this embodiment, the temperature of the first oil 46 or the second oil 55 is estimated based on the ambient temperature or the temperature of the drive motors 4 (front drive motor 4f, rear drive motor 4r).

[0068] This allows for the estimation of the temperature of the first oil 46 or the second oil 55 using a simple method.

[0069] In this embodiment, when the acceleration of the vehicle 100 falls below a predetermined value, the output state of the first drive motor (front drive motor 4f) is gradually changed from a powering state related to the combined driving force to a regenerative state related to regenerative braking force, and the output state of the second drive motor (rear drive motor 4r) is gradually changed from a regenerative state related to regenerative braking force to a powering state related to the combined driving force.

[0070] When vehicle 100 is accelerating, it is unstable, but it becomes stable during cruising at a constant speed. Therefore, when the acceleration falls below a predetermined value determined experimentally, the output state of the first drive motor (front drive motor 4f) (drive state related to the combined driving force) and the output state of the second drive motor (rear drive motor 4r) (regenerative state related to a predetermined regenerative driving force) are switched between each other. As a result, since the output in the accelerating state is greater than the output in the regenerative state, the first oil 46 (second oil 55) that cools the second drive motor (rear drive motor 4r) can be heated efficiently.

[0071] In this embodiment, when the acceleration of the vehicle 100 falls below a predetermined value, the output state of the first drive motor (front drive motor 4f) is gradually changed from a powering state related to the combined driving force to a regenerative state related to regenerative braking force, and the output state of the second drive motor (rear drive motor 4r) is gradually changed from a regenerative state related to regenerative braking force to a powering state related to the combined driving force so as to maintain a state in which the combined force of the first drive motor (front drive motor 4f) and the second drive motor (rear drive motor 4r) becomes the required driving force.

[0072] The above method makes it possible to suppress the decrease in the driving stability of the vehicle 100 when switching between the output state of the first drive motor (front drive motor 4f) and the output state of the second drive motor (rear drive motor 4r).

[0073] The control device for the electric vehicle of this embodiment includes a motor body (stator 42, rotor core 43, rotor shaft 44) that drives the motor shaft (rotor shaft 44), a motor case 41 that houses the motor body, a drive motor 4 in which a first oil 46 for cooling the motor body is housed in the motor case 41, a drive shaft 8 that pivotally supports the drive wheel 9, a gear mechanism (reduction gear 52, differential gear 53) that engages the motor shaft (rotor shaft 44) by gear coupling, and a gear case 51 that houses the gear mechanism. The drive motor 4 includes a gearbox 5 in which a second oil 55 for cooling the gear mechanism is housed in case 51, and the drive motor 4 includes a first drive motor (e.g., front drive motor 4f) for transmitting driving force to a first drive wheel (e.g., front wheel 9f) located on one side of the vehicle 100 in the longitudinal direction (e.g., front) of the drive wheels 9, and a second drive motor (rear drive motor 4r) for transmitting driving force to a second drive wheel (rear wheel 9r) located on the other side of the vehicle 100 in the longitudinal direction (e.g., rear) of the drive wheels 9, and the gearbox 5 includes a first drive motor (front drive motor 4f) for transmitting driving force to a first drive wheel (e.g., front wheel 9f) located on the other side of the vehicle 100 in the longitudinal direction (e.g., rear) of the drive wheels 9, and the drive motor 4 includes a first drive motor (front drive motor 4f) for transmitting driving force to a second drive wheel (rear drive motor 4r) A control device for an electric vehicle, comprising: a first gearbox (front gearbox 5f) that transmits the driving force of a front drive motor (4f) to the first drive wheel (front wheel 9f); a second gearbox (rear gearbox 5r) that transmits the driving force of a second drive motor (rear drive motor 4r) to the second drive wheel (rear wheel 9r); and a control unit (controller 2) that distributes all the requested driving force requested by the driver to the first drive motor (front drive motor 4f) when the vehicle 100 is started, wherein the control unit (controller 2) distributes all the requested driving force requested by the driver to the first drive motor (front drive motor 4f) when the vehicle 100 is started. When the temperature of oil 1 46 or oil 2 55 is lower than a predetermined temperature, the output state of the first drive motor (front drive motor 4f) is set to the powering state and the output state of the second drive motor (rear drive motor 4r) is set to the regenerative state, the braking force of the second drive motor (rear drive motor 4r) is set to a predetermined regenerative braking force, the driving force of the first drive motor (front drive motor 4f) is set to a combined driving force which is the sum of a counteracting driving force that cancels out the regenerative braking force and the required driving force, and the magnitude of the regenerative braking force is set to half or less of the magnitude of the required driving force.

[0074] With the above configuration, the first oil 46 and second oil 55 that cool the first drive motor (front drive motor 4f) can be warmed up by the heat generated when the first drive motor (front drive motor 4f) outputs the combined driving force, and the first oil 46 and second oil 55 that cool the second drive motor (rear drive motor 4r) can be warmed up by the heat generated when the second drive motor (rear drive motor 4r) outputs the regenerative braking force. Furthermore, the warming up of the first oil 46 and second oil 55 and the charging of the battery 1 can be performed without interfering with the driving of the vehicle 100, and the regenerative braking force can be efficiently determined in relation to the required driving force.

[0075] In this embodiment, the drive motor 4 and the gearbox 5 are integrally formed in such a manner that a partition wall 47 is formed by a part of the outer wall of the motor case 41 and a part of the outer wall of the gear case 51 being integrated. The drive motor 4 includes a first oil pan 45 for storing first oil 46 and a circulation mechanism (circulation pump) for circulating the first oil 46 stored in the first oil pan 45 to the motor body (stator 42, rotor core 43, rotor shaft 44). The gearbox 5 includes a second oil pan 54 for storing second oil 55. The gear mechanism (reduction gear 52, differential gear 53) includes a second oil pan 54. The gear mechanism comes into contact with the second oil 55 stored in the oil pan 54, and as the gear mechanism rotates, it scrapes up the second oil 55 and supplies it to the gear mechanism, thereby being cooled by the second oil 55. The first oil pan 45 is formed such that the surface of the partition wall 47 facing the motor case 41 is part of the inner wall of the first oil pan 45, and the second oil pan 54 is formed such that the surface of the partition wall 47 on the opposite side of the first oil pan 45 is part of the inner wall of the second oil pan 54. The first oil 46 stored in the first oil pan 45 and the second oil 55 stored in the second oil pan 54 overlap each other in the height direction.

[0076] With the above configuration, the first oil 46 and the second oil 55 are arranged facing each other with a partition wall 47 in between, so that heat exchange between the first oil 46 and the second oil 55 can be performed efficiently. In particular, when heating the first oil 46 and the second oil 55, the heat from the second oil 55 heated by the gear mechanism (reduction gear 52, differential gear 53) can be efficiently transferred to the first oil 46, allowing the first oil 46 to be heated in a short time and reducing the friction torque of the drive motor 4 and gearbox 5 in a short time. Conversely, if the temperature of the motor body is higher than that of the gear mechanism, the heat from the first oil 46 heated by the motor body (stator 42, rotor core 43, rotor shaft 44) can be efficiently transferred to the second oil 55, allowing the second oil 55 to be heated in a short time and reducing the friction torque of the drive motor 4 and gearbox 5 in a short time.

[0077] Although embodiments of the present invention have been described above, these embodiments only represent a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments. Furthermore, the above embodiments can be combined as appropriate. [Explanation of Symbols]

[0078] 2 Controller, 4 Drive motor, 4f Front drive motor, 4r Rear drive motor, 41 Motor case, 42 Stator, 43 Rotor core, 44 Rotor shaft, 46 First oil, 5 Gearbox, 5f Front gearbox, 5r Rear gearbox, 51 Gear case, 52 Reducer, 53 Differential gear, 55 Second oil, 9 Drive wheels, 9f Front wheels, 9r Rear wheels, 100 Vehicle

Claims

1. A motor body that drives the motor shaft, a motor case that houses the motor body, and a drive motor in which a first oil for cooling the motor body is contained within the motor case, A gearbox comprising a drive shaft that supports a drive wheel, a gear mechanism that engages the motor shaft with a gear coupling, and a gear case that houses the gear mechanism, wherein a second oil for cooling the gear mechanism is contained within the gear case, The drive motor includes a first drive motor for transmitting driving force to a first drive wheel located on one of the drive wheels in the longitudinal direction of the vehicle, and a second drive motor for transmitting driving force to a second drive wheel located on the other of the drive wheels in the longitudinal direction of the vehicle. The gearbox includes a first gearbox that transmits the driving force of the first drive motor to the first drive wheel, and a second gearbox that transmits the driving force of the second drive motor to the second drive wheel. A control method for an electric vehicle, wherein all of the requested driving force requested by the driver at the time of starting the vehicle is distributed to the first drive motor, When the vehicle is started, if the temperature of the first oil or the second oil is lower than a predetermined temperature, the output state of the first drive motor is set to the powering state and the output state of the second drive motor is set to the regenerative state. The braking force of the second drive motor is set to a predetermined regenerative braking force, The driving force of the first drive motor is set to a combined driving force obtained by adding the offsetting driving force that cancels out the regenerative braking force and the required driving force. A control method for an electric vehicle that sets the magnitude of the regenerative braking force to half or less of the magnitude of the required driving force.

2. A control method for an electric vehicle according to claim 1, wherein the temperature of the first oil or the temperature of the second oil is estimated based on the ambient temperature or the temperature of the drive motor.

3. A control method for an electric vehicle according to claim 1, wherein when the acceleration of the vehicle falls below a predetermined value, the output state of the first drive motor is gradually changed from a powering state relating to the total driving force to a regenerative state relating to the regenerative braking force, and the output state of the second drive motor is gradually changed from a regenerative state relating to the regenerative braking force to a powering state relating to the total driving force.

4. A control method for an electric vehicle according to claim 1, wherein when the acceleration of the vehicle falls below a predetermined value, the output state of the first drive motor is gradually changed from a powering state relating to the combined driving force to a regenerative state relating to the regenerative braking force, and the output state of the second drive motor is gradually changed from a regenerative state relating to the regenerative braking force to a powering state relating to the combined driving force so as to maintain a state in which the resultant force of the first drive motor and the second drive motor equals the required driving force.

5. A motor body that drives the motor shaft, a motor case that houses the motor body, and a drive motor in which a first oil for cooling the motor body is contained within the motor case, A gearbox comprising a drive shaft that supports a drive wheel, a gear mechanism that engages the motor shaft with a gear coupling, and a gear case that houses the gear mechanism, wherein a second oil for cooling the gear mechanism is contained within the gear case, The drive motor includes a first drive motor for transmitting driving force to a first drive wheel located on one of the drive wheels in the longitudinal direction of the vehicle, and a second drive motor for transmitting driving force to a second drive wheel located on the other of the drive wheels in the longitudinal direction of the vehicle. The gearbox includes a first gearbox that transmits the driving force of the first drive motor to the first drive wheel, and a second gearbox that transmits the driving force of the second drive motor to the second drive wheel, and further, A control device for an electric vehicle, comprising: a control unit that distributes all the requested driving force requested by the driver to the first drive motor when the vehicle is started, The control unit, When the vehicle is started, if the temperature of the first oil or the second oil is lower than a predetermined temperature, the output state of the first drive motor is set to the powering state and the output state of the second drive motor is set to the regenerative state. The braking force of the second drive motor is set to a predetermined regenerative braking force, The driving force of the first drive motor is set to a combined driving force obtained by adding the offsetting driving force that cancels out the regenerative braking force and the required driving force. A control device for an electric vehicle that sets the magnitude of the regenerative braking force to less than or equal to half the magnitude of the required driving force.

6. The drive motor and the gearbox are integrally formed in such a manner that a portion of the outer wall of the motor case and a portion of the outer wall of the gear case form a partition wall. The drive motor includes a first oil pan for storing the first oil, and a circulation mechanism for circulating the first oil stored in the first oil pan to the motor body. The gearbox includes a second oil pan for storing the second oil, The gear mechanism comes into contact with the second oil stored in the second oil pan, and the gear mechanism rotates, scooping up the second oil and supplying it to the gear mechanism, thereby being cooled by the second oil. The first oil pan is formed such that the surface of the partition wall facing the motor case becomes part of the inner wall of the first oil pan. The second oil pan is formed such that the side of the partition wall opposite to the first oil pan is part of the inner wall of the second oil pan. The control device for an electric vehicle according to claim 5, wherein the first oil stored in the first oil pan and the second oil stored in the second oil pan overlap each other in the height direction.

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