Vehicle

Abstract

To improve an energy efficiency in a vehicle comprising a plurality of motors.SOLUTION: A vehicle 100 comprises: a first motor which gives driving power to a first wheel via a first speed reducer; a second motor which gives driving power to a second wheel via a second speed reducer; and a controller 500 which controls the driving power of the first motor and the driving power of the second motor. A maximum driving power that the first motor can output is larger than a maximum driving power that the second motor can output. The controller 500 drives the second motor in priority to the first motor when a temperature parameter correlating with a temperature of the first speed reducer and a temperature of the second speed reducer is lower than a predetermined temperature.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a vehicle including a plurality of motors.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2012-034433 (Patent Document 1) discloses a technique for a vehicle including a first motor and a second motor. When the output required for the vehicle (required driving force) is equal to or less than the smaller of the allowable outputs of the first motor and the second motor, the motor on the lower temperature side of the first motor and the second motor is selected and operated. In this technique, when the temperature difference between the first motor and the second motor does not reach a predetermined value, switching from the first motor to the second motor or switching from the second motor to the first motor is prohibited.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the above technique, by driving only the motor on the lower temperature side of the first motor and the second motor, it is possible to reduce the temperature difference between the first motor and the second motor. However, from the viewpoint of energy efficiency, it is not always preferable to stop the motor on the higher temperature side and drive only the motor on the lower temperature side. Further, Patent Document 1 does not mention how to control each motor when the temperatures of both the first motor and the second motor are low. In a vehicle in which a motor applies a driving force to a wheel via a speed reducer, when the temperature of the speed reducer becomes too low, the energy loss tends to increase.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to improve energy efficiency in a vehicle including a plurality of motors.

Means for Solving the Problems

[0006] According to one aspect of the present disclosure, a vehicle having the following configuration is provided. The vehicle includes a first motor that applies a driving force to a first wheel via a first speed reducer, a second motor that applies a driving force to a second wheel via a second speed reducer, and a control device that controls the driving force of the first motor and the driving force of the second motor. The maximum driving force that the first motor can output is greater than the maximum driving force that the second motor can output. When a temperature parameter correlated with the temperature of the first speed reducer and the temperature of the second speed reducer is lower than a predetermined temperature, the control device preferentially drives the second motor rather than the first motor.

Advantages of the Invention

[0007] According to the present disclosure, it becomes possible to improve energy efficiency in a vehicle including a plurality of motors.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0009] Embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their description will not be repeated.

[0010] FIG. 1 is a diagram showing a schematic configuration of a vehicle according to this embodiment. Referring to FIG. 1, the vehicle 100 includes motors 110 and 210, inverters 120 and 220, speed reducers 130 and 230, axles 140 and 240, a power storage device 300, lubrication devices 10 and 20, a cooling device 30, heat exchangers 41 and 42, a control device 500, and wheels W1 to W4. The cooling device 30 is configured to be heat-exchangeable with each of the lubrication devices 10 and 20. The cooling device 30 is configured to cool the inverters 120 and 220 and the power storage device 300. The control device 500 is configured to control the inverters 120 and 220, the lubrication devices 10 and 20, and the cooling device 30. The vehicle 100 is, for example, a four-wheel BEV (battery electric vehicle) configured to be capable of traveling using the electric power output from the power storage device 300.

[0011] The wheels W1 and W2, the motor 110, the speed reducer 130, and the axle 140 are arranged in the front portion of the vehicle 100. A wheel W1 is attached to one end of the axle 140, and a wheel W2 is attached to the other end. Each of the wheels W1 and W2 corresponding to the front wheels of the vehicle 100 corresponds to an example of the "first wheel" according to the present disclosure. The motor 110, the speed reducer 130, and the axle 140 are mechanically connected to each other. The motor 110 applies a driving force (torque) to the axle 140 (and thus the wheels W1 and W2) via the speed reducer 130.

[0012] The inverter 120 functions as a PCU (Power Control Unit) for the motor 110. The inverter 120 generates driving power for the motor 110 using the electric power supplied from the power storage device 300. The motor 110 is driven by the inverter 120 to rotate the wheels W1 and W2. The torque output by the motor 110 is transmitted to the axle 140 (and thus the wheels W1 and W2) via the speed reducer 130.

[0013] The lubrication device 10 includes an oil circuit P1 (first oil circuit) through which the lubricating oil of the speed reducer 130 circulates, a pump 11, and a temperature sensor 12 (first temperature sensor). The pump 11 functions as an oil pump. The pump 11 is controlled by a control device 500 to circulate the lubricating oil of the speed reducer 130 through the oil circuit P1. The oil circuit P1 passes through the motor 110, the speed reducer 130, and the heat exchanger 41. The lubrication device 10 supplies lubricating oil to the motor 110 and the speed reducer 130 and cools the motor 110 and the speed reducer 130 with the lubricating oil. Since such a cooling method can directly supply oil to the heat-generating part for cooling, the cooling effect is high. The temperature sensor 12 detects the temperature of the lubricating oil of the speed reducer 130 flowing through the oil circuit P1 and outputs the detection result to the control device 500.

[0014] The wheels W3, W4, the motor 210, the speed reducer 230, and the axle 240 are arranged at the rear part of the vehicle 100. A wheel W3 is attached to one end of the axle 240, and a wheel W4 is attached to the other end. Each of the wheels W3, W4 corresponding to the rear wheels of the vehicle 100 corresponds to an example of the "second wheel" according to the present disclosure. The motor 210, the speed reducer 230, and the axle 240 are mechanically connected to each other. The motor 210 applies a driving force (torque) to the axle 240 (and thus the wheels W3, W4) via the speed reducer 230.

[0015] The inverter 220 functions as a PCU (Power Control Unit) for the motor 210. The inverter 220 generates driving power for the motor 210 using the power supplied from the power storage device 300. The motor 210 is driven by the inverter 220 to rotate the wheels W3, W4. The torque output by the motor 210 is transmitted to the axle 240 (and thus the wheels W3, W4) via the speed reducer 230.

[0016] The lubrication device 20 includes an oil circuit P2 (second oil circuit) through which the lubricating oil of the speed reducer 230 circulates, a pump 21, and a temperature sensor 22 (second temperature sensor). The pump 21 functions as an oil pump. The pump 21 is controlled by the control device 500 to circulate the lubricating oil of the speed reducer 230 through the oil circuit P2. The oil circuit P2 passes through the motor 210, the speed reducer 230, and the heat exchanger 42. The lubrication device 20 supplies lubricating oil to the motor 210 and the speed reducer 230, and cools the motor 210 and the speed reducer 230 with the lubricating oil. Such a cooling method has a high cooling effect because the oil can be directly passed through the heat generating part for cooling. The temperature sensor 22 detects the temperature of the lubricating oil of the speed reducer 230 flowing through the oil circuit P2 and outputs the detection result to the control device 500.

[0017] The cooling device 30 includes three-way valves 31, 32, a pump 33, a temperature sensor 34, and passages P31, P32, P32a, P33, P34, P34a, P35 through which the refrigerant flows. The pump 33 is configured to receive the refrigerant from the passage P35 and send the refrigerant to the passage P31. The refrigerant flowing through the passages P35 and P31 exchanges heat with the inverters 120 and 220, respectively. Thereby, the inverters 120 and 220 are cooled. Also, the refrigerant flowing through each of the passages P31 and P33 exchanges heat with the power storage device 300. Thereby, the power storage device 300 is cooled. The temperature sensor 34 detects the temperature of the refrigerant and outputs the detection result to the control device 500. In this embodiment, water is adopted as the refrigerant, and a water pump is adopted as the pump 33. However, the type of the refrigerant can be changed as appropriate. The refrigerant is not limited to a liquid and may be a gas. The cooling device 30 may be configured to be able to adjust the temperature of the refrigerant. The cooling device 30 may be configured to be able to exchange heat with a refrigeration cycle for an air conditioner, for example.

[0018] Of the three ports of the three-way valve 32, the first port (inlet) is connected to the passage P31, the second port (first outlet) is connected to the passage P32, and the third port (second outlet) is connected to the passage P32a. The three-way valve 32 connects one of the second port and the third port specified by the control device 500 to the first port. The passage P32 is connected to the passage P33 through the heat exchanger 42. The passage P32a is connected to the passage P33 without passing through the heat exchanger 42. The passage P32a corresponds to a bypass passage.

[0019] Of the three ports of the three-way valve 31, the first port (inlet) is connected to the passage P33, the second port (first outlet) is connected to the passage P34, and the third port (second outlet) is connected to the passage P34a. The three-way valve 31 connects one of the second port and the third port specified by the control device 500 to the first port. The passage P34 is connected to the passage P35 through the heat exchanger 41. The passage P34a is connected to the passage P35 without passing through the heat exchanger 41. The passage P34a corresponds to a bypass passage.

[0020] In this embodiment, the maximum driving force that the motor 110 can output is greater than the maximum driving force that the motor 210 can output. The motors 110 and 210 function as a main driving motor (first motor) and a sub-driving motor (second motor), respectively. The sensitivity of the loss with respect to the rotational speed is smaller for the motor 210 than for the motor 110. The control device 500 controls the driving force of the motor 110 and the driving force of the motor 210. The control device 500 can individually change the outputs of the motors 110 and 210 by means of the inverters 120 and 220.

[0021] FIG. 2 is a diagram for explaining first motor control executed by the control device 500. Referring to FIG. 2, the vehicle 100 further includes an HMI (Human Machine Interface) 600. The HMI 600 includes, for example, an input device and a display device. The HMI 600 may include an operation unit (for example, an accelerator pedal, a brake pedal, and a steering wheel) for a user to request acceleration, deceleration, and steering of the vehicle 100 (control device 500). In addition, various sensors (not shown) are also mounted on the vehicle 100. The in-vehicle sensors may include, for example, sensors that detect the states of the motors 110 and 210, and sensors that detect the input power and output power of the inverters 120 and 220.

[0022] The control device 500 includes a processor 510 and a storage device 520. The storage device 520 is configured to be able to store stored information. In addition to programs, various information used in the programs is stored in the storage device 520. In this embodiment, by the processor 510 executing the programs stored in the storage device 520, for example, the control described below is executed. However, these controls may be executed only by hardware (electronic circuits) without using software.

[0023] The control device 500 executes each processing flow shown in a flowchart in FIG. 2 and FIG. 3 described later. "S" in the flowchart means a step. The storage device 520 stores a flag FG used in these processing flows. The flag FG indicates the driving mode of the vehicle 100. The initial value of the flag FG is set to, for example, "0".

[0024] The control device 500 starts the processing flow F1 triggered by, for example, the startup of the control system (including the control device 500) of the vehicle 100. In S11, the control device 500 calculates the required driving force required for the vehicle 100. In the vehicle 100 during manual driving, the control device 500 may calculate the required driving force based on, for example, the state of the vehicle 100 (such as vehicle speed, load, etc.) and the driving requests from the user (such as accelerator operation amount, brake operation amount, steering angle, etc.). Also, the vehicle 100 may be configured to enable autonomous driving. The vehicle 100 may be equipped with a camera and / or radar for recognizing the surrounding situation. In the vehicle 100 during autonomous driving, the control device 500 may calculate the required driving force based on, for example, the state of the vehicle 100 and the surrounding situation of the vehicle 100 (such as pedestrians, other vehicles, road gradient, road signs, traffic lights, etc.).

[0025] In the subsequent S12, the control device 500 determines whether the flag FG is "0". Initially, since the flag FG is "0", it is determined as YES in S12, and the process proceeds to S13. In S13, the control device 500 controls the inverters 120 and 220 so as to generate the required driving force calculated in S11 by driving the motors 110 and 210.

[0026] Specifically, the control device 500 controls the driving force of the motor 110 and the driving force of the motor 210 so that the total value of the driving forces applied to all the drive wheels (wheels W1 to W4) provided in the vehicle 100 approaches the required driving force. At this time, the control device 500 may determine the driving force distribution between the driving force of the motor 110 (main drive motor) and the driving force of the motor 210 (sub-drive motor) so that the difference between the temperature of the lubricating oil of the speed reducer 130 and the temperature of the lubricating oil of the speed reducer 230 becomes small. The driving force distribution is represented by, for example, the ratio of the driving force of the motor 110 to the sum of the driving forces of the motor 110 and the motor 210 (total driving force) (hereinafter, also referred to as "main drive distribution"). The main drive distribution is represented by an equation such as "main drive distribution = driving force of main drive motor / total driving force". In the control of S13, the higher the main drive distribution, the higher the temperature of the lubricating oil of the speed reducer 130 tends to be, and the lower the temperature of the lubricating oil of the speed reducer 230 tends to be. When the temperature of the lubricating oil of the speed reducer 130 is lower than the temperature of the lubricating oil of the speed reducer 230, increasing the main drive distribution makes it easier for the temperature difference between the two to become small. When the temperature of the lubricating oil of the speed reducer 130 is higher than the temperature of the lubricating oil of the speed reducer 230, decreasing the main drive distribution makes it easier for the temperature difference between the two to become small. In S13, the main drive distribution is set to a value greater than "0" and less than "1". In S13, both the motors 110 and 210 are in an operating state, and four-wheel drive (4WD) is executed.

[0027] In the subsequent S21, the control device 500 determines whether a temperature parameter (hereinafter referred to as "To") correlated with the temperature of the speed reducer 130 and the temperature of the speed reducer 230 is lower than a predetermined temperature (hereinafter referred to as "Th1"). The main body of the speed reducer 130 exchanges heat with the lubricating oil flowing through the oil circuit P1. Therefore, the temperature of the speed reducer 130 and the temperature of the lubricating oil of the speed reducer 130 are correlated. The main body of the speed reducer 230 exchanges heat with the lubricating oil flowing through the oil circuit P2. Therefore, the temperature of the speed reducer 230 and the temperature of the lubricating oil of the speed reducer 230 are correlated. In this embodiment, the average value of the temperature of the lubricating oil of the speed reducer 130 (first oil temperature) detected by the temperature sensor 12 and the temperature of the lubricating oil of the speed reducer 230 (second oil temperature) detected by the temperature sensor 22 is set as To. However, it is not limited to this, and the added value of the first oil temperature and the second oil temperature may be adopted as To. Also, among the first oil temperature and the second oil temperature, the lower temperature or the higher temperature may be adopted as To. Th1 may be set according to the characteristics of the lubricating oil (for example, the relationship between viscosity and temperature). The lubricating oil of the speed reducer tends to have a higher viscosity as the temperature decreases. And when the temperature of the lubricating oil of the speed reducer becomes too low, the loss of the speed reducer tends to increase due to the increase in the viscosity of the lubricating oil. Th1 may be the boundary temperature at which the viscosity of the lubricating oil becomes greater than the appropriate range.

[0028] If To is lower than Th1 (YES in S21), in S22, the control device 500 determines whether the required driving force is less than or equal to the maximum driving force of the motor 210. If the required driving force is less than or equal to the maximum driving force of the motor 210 (YES in S22), the process proceeds to S23. In S23, the control device 500 sets the main drive distribution to "0" and sets the flag FG to "1". Setting the main drive distribution to "0" means that the drive force distribution (main:sub) becomes "0:10". The control device 500 stops the motor 110 and generates the required driving force by the motor 210 according to this main drive distribution. Thereby, the drive mode is changed from 4WD to two-wheel drive (2WD). The fact that the required driving force is less than or equal to the maximum driving force of the motor 210 means that the required driving force can be output only by the motor 210.

[0029] When the required driving force is greater than the maximum driving force of the motor 210 (NO in S22), in S24, the control device 500 determines whether the required driving force is less than or equal to the maximum driving force of the motor 110. If the required driving force is less than or equal to the maximum driving force of the motor 110 (YES in S24), the process proceeds to S25. In S25, the control device 500 sets the main drive distribution to "1" and sets "2" to the flag FG. Setting the main drive distribution to "1" means that the driving force distribution (main:sub) becomes "10:0". The control device 500 stops the motor 210 and generates the required driving force by the motor 110 according to this main drive distribution. Thereby, the driving mode is changed from 4WD to 2WD.

[0030] When the process of S23 or S25 is executed, the process returns to the first step (S11). In this case, since the flag FG is "1" or "2", it is determined as NO in S12 and the process proceeds to S14. In S14, the control device 500 controls the inverters 120 and 220 so that the required driving force calculated in S11 is generated by the operating motor (either one of the motors 110 and 210). Two-wheel drive (2WD) is executed by the operating motor. The operating motor is the motor 210 when the flag FG is "1", and the motor 110 when the flag FG is "2". Then, the process returns to S11. While the flag FG is not "0", the processes of S11, S12, and S14 are repeated.

[0031] When To is greater than or equal to Th1 (NO in S21) as well, the process returns to S11. Also, when the required driving force is greater than the maximum driving force of the motor 110 (NO in S24), the process returns to S11. However, in these cases, the flag FG is "0". Therefore, it is determined as YES in S12 and the process of the aforementioned S13 is executed. While the flag FG is "0", the processes of S11 to S13 are repeatedly executed.

[0032] The control device 500 executes the processing flow F3 shown in FIG. 3 in parallel with the processing flow F1 shown in FIG. 2. For example, when the control system of the vehicle 100 is activated, the processing flow F3 is started together with the processing flow F1. FIG. 3 is a diagram for explaining the second motor control executed by the control device 500.

[0033] Referring to FIG. 3, in S31, the control device 500 determines whether or not the flag FG is "0". Initially, since the flag FG is "0", it is determined as YES in S31, and the process proceeds to S32. When the flag FG is "0", both the motors 110 and 210 are in an operating state (see S13 in FIG. 2). In S32, the control device 500 controls the cooling device 30 shown in FIG. 1 so that the lubricating oil of the speed reducer 130 mechanically connected to the motor 110 and the lubricating oil of the speed reducer 230 mechanically connected to the motor 210 are each cooled. In S32, all of the pumps 11, 21, and 33 are in an operating state.

[0034] Specifically, the control device 500 controls the three-way valves 31 and 32 so that the passage P31 and the passage P32 are connected, and the passage P33 and the passage P34 are connected. And in this state, the control device 500 controls the pump 33 so that the refrigerant (cooling water) flows through the passages P31, P32, P33, P34, and P35 in order. By the heat exchanger 41, the lubricating oil of the speed reducer 130 flowing through the oil circuit P1 and the refrigerant (cooling water) flowing through the passage P34 exchange heat. The lubricating oil of the speed reducer 130 is cooled by this heat exchange. Also, by the heat exchanger 42, the lubricating oil of the speed reducer 230 flowing through the oil circuit P2 and the refrigerant (cooling water) flowing through the passage P32 exchange heat. The lubricating oil of the speed reducer 230 is cooled by this heat exchange. When the process of S32 is executed, the process returns to the first step (S31). While the flag FG is "0", the cooling (S32) of the lubricating oil of each speed reducer by the cooling device 30 is continuously executed.

[0035] In the processing flow F1 (Figure 2) executed in parallel with the processing flow F3, when the flag FG becomes not "0" due to the execution of the process in S23 or S25, it is determined as NO in S31, and the process proceeds to S33. When the flag FG is not "0", one of the motors 110 and 210 is in the stopped state and the other is in the operating state. In S33, the control device 500 controls the cooling device 30 shown in FIG. 1 so that the lubricating oil of the speed reducer 130 or 230 mechanically connected to the operating motor is cooled, and the lubricating oil of the speed reducer 230 or 130 mechanically connected to the stopped motor is not cooled. Specifically, the cooling control described below is executed. Thereby, it is suppressed that the temperature of the lubricating oil of the speed reducer mechanically connected to the operating motor rises too much, and the temperature of the lubricating oil of the speed reducer mechanically connected to the stopped motor is likely to rise. According to such a configuration, it becomes easy to appropriately execute the heat management of each of the front portion and the rear portion of the vehicle 100.

[0036] For example, when the flag FG is "1", the motor 210 (sub-drive motor) is in the operating state and the motor 110 (main-drive motor) is in the stopped state. In this case, in S33, the control device 500 controls the three-way valves 31 and 32 so that the passage P31 and the passage P32 are connected, and the passage P33 and the passage P34a are connected. In this state, the control device 500 drives the pump 33. In this case, the refrigerant (cooling water) passes through the heat exchanger 42 but does not pass through the heat exchanger 41. The lubricating oil of the speed reducer 230 is cooled by the heat exchange in the heat exchanger 42. On the other hand, the lubricating oil of the speed reducer 130 is not cooled by the refrigerant (cooling water). Further, the control device 500 stops the pump 11. Thereby, the power consumption is reduced.

[0037] Also, when the flag FG is "2", the motor 110 (main drive motor) is in the operating state and the motor 210 (sub-drive motor) is in the stopped state. In this case, the control device 500 controls the three-way valves 31 and 32 in S33 such that the passage P31 and the passage P32a are connected, and the passage P33 and the passage P34 are connected. In this state, the control device 500 drives the pump 33. In this case, the refrigerant (cooling water) passes through the heat exchanger 41 but does not pass through the heat exchanger 42. The lubricating oil of the speed reducer 130 is cooled by the heat exchange in the heat exchanger 41. On the other hand, the lubricating oil of the speed reducer 230 is not cooled by the refrigerant (cooling water). Also, the control device 500 stops the pump 21. Thereby, the power consumption is reduced.

[0038] When the flag FG is not "0", the control device 500 executes the above cooling control (S33). Subsequently, the control device 500 determines in S34 whether to cancel the setting of the driving force distribution (the state where the main drive distribution is set to "0" or "1"). Specifically, the control device 500 executes the processing flows F4 and F5 in parallel in S34.

[0039] In the processing flow F4, the control device 500 determines in S41 whether the latest required driving force calculated in S11 of FIG. 2 is greater than the maximum driving force of the operating motor. If the required driving force is greater than the maximum driving force of the operating motor (YES in S41), the control device 500 sets "0" to the flag FG in S42. Thereby, the setting of the driving force distribution is canceled, and it becomes YES in S12 of FIG. 2. Then, both the motors 110 and 210 are in the operating state in S13. The fact that the required driving force exceeds the maximum driving force of the operating motor means that the required driving force cannot be output only by the operating motor.

[0040] When the process of S42 is executed, the processing flow F4 ends. If the required driving force does not exceed the maximum driving force of the operating motor (NO in S41), the process of S42 is not executed. In this case, the flag FG remains "1" or "2", and the processing flow F4 ends.

[0041] In processing flow F5, at S51, the control device 500 determines whether the aforementioned To is higher than a predetermined temperature (hereinafter referred to as "Th2"). Th2 may be the same temperature as Th1 or a temperature higher than Th1. When the flag FG is "1" or "2", the required driving force is generated by only one motor (S14 in FIG. 2). As a result, the motor in operation is more likely to generate heat than when the required driving force is generated by two motors, and the temperature of the speed reducer mechanically connected to the motor in operation is likely to increase. Also, since the cooling water passage for cooling the motor and its speed reducer during stoppage is blocked (see S33), the temperature of the speed reducer mechanically connected to the motor during stoppage is also likely to increase. For this reason, To rises. When To becomes higher than Th2 (YES at S51), the process proceeds to S52.

[0042] At S52, the control device 500 determines whether the latest required driving force calculated at S11 in FIG. 2 is greater than a predetermined value (hereinafter referred to as "Th3"). Th3 is smaller than the maximum driving force of the motor 210. Th3 may be a boundary value at which the required driving force becomes greater than the recommended range of 2WD. When the required driving force is greater than Th3 (YES at S52), the control device 500 sets "0" in the flag FG at S53. As a result, the setting of the driving force distribution is cancelled, and it comes to be judged YES at S12 in FIG. 2. Then, both the motor 110 and 210 are in an operating state at S13. When the process of S53 is executed, the processing flow F5 ends.

[0043] If it is judged NO at S51 or S52, the process of S53 is not executed and the processing flow F5 ends. In S34, when both the processing flows F4 and F5 are executed, the process returns to S31. Thus, the processing flow F3 is repeatedly executed.

[0044] As described above, the motor control method according to this embodiment includes each process of processing flows F1, F3, F4, and F5. When the temperature parameter (To) correlated with the temperature of the speed reducer 130 (first speed reducer) and the temperature of the speed reducer 230 (second speed reducer) is lower than a predetermined temperature, the control device 500 preferentially drives the motor 210 (second motor) over the motor 110 (first motor) (S21 to S25 in FIG. 2). When To becomes low, it is estimated that the temperatures of the speed reducers 130 and 230 are low. In such a case, by preferentially driving the motor 210 over the motor 110, the temperature of the speed reducer 230 can be increased. The control device 500 acquires To using the detection results of each of the temperature sensors 12 and 22. According to such a configuration, it becomes easier to manage the lubricating oil of the speed reducer at an appropriate temperature. Thus, by suppressing the temperature of the speed reducer (for example, the temperature of the lubricating oil) from becoming too low, an increase in loss can be suppressed. Moreover, driving the motor 210 with a smaller maximum driving force rather than driving the motor 110 with a larger maximum driving force results in better heat generation efficiency (efficiency of converting electric power into heat). Also, since the motor 210 tends to have less loss than the motor 110, driving the motor 210 rather than driving the motor 110 results in better electricity costs (power consumption rate). According to the above configuration, early warm-up becomes possible without using additional energy. Therefore, the energy efficiency is improved in the vehicle 100 including a plurality of motors.

[0045] When the control device 500 determines whether a predetermined first condition is satisfied while generating the required driving force required for the vehicle 100 by the motors 110 and 210 (S21, S22 in FIG. 2). The first condition is satisfied when the temperature parameter (To) is lower than a predetermined temperature (Th1) and the required driving force is equal to or less than the maximum driving force of the motor 210. When it is determined that the first condition is satisfied (YES in both S21 and S22), the control device 500 stops the motor 110 and generates the required driving force by the motor 210 (S23 in FIG. 2). By stopping the motor 110, the power consumption can be reduced. Also, if the required driving force is equal to or less than the maximum driving force of the motor 210, it is considered that the vehicle can still run even if the motor 110 is stopped. According to the above configuration, it is possible to suppress an increase in loss caused by an excessive decrease in the temperature of the speed reducer while suppressing any hindrance to the operation of the vehicle.

[0046] When it is determined that the above first condition is not satisfied (NO in S22 of FIG. 2), the control device 500 determines whether a predetermined second condition is satisfied (S24 in FIG. 2). The second condition is satisfied when the temperature parameter (To) is lower than a predetermined temperature (Th1), the required driving force is greater than the maximum driving force of the motor 210, and is equal to or less than the maximum driving force of the motor 110. When it is determined that the second condition is satisfied (YES in S21, NO in S22, and YES in S24), the control device 500 stops the motor 210 and generates the required driving force by the motor 110 (S25 in FIG. 2). In this way, by stopping the motor 210 and driving the motor 110, the temperature of the speed reducer 130 can be increased. Thereby, it is possible to suppress the temperature of the speed reducer from becoming too low and suppress an increase in loss. Also, by stopping the motor 210, the power consumption can be reduced. Furthermore, if the required driving force is equal to or less than the maximum driving force of the motor 110, it is considered that the operation of the vehicle 100 is not hindered even if the motor 210 is stopped.

[0047] When one of the motors 110 and 210 is in the stopped state and the other is in the operating state, the control device 500 determines whether or not a predetermined third condition is satisfied (S34 in FIG. 3). The third condition is satisfied when the maximum driving force that the operating motor can output exceeds the required driving force required for the vehicle 100. When it is determined that the third condition is satisfied (YES in S41), the control device 500 sets both the motors 110 and 210 to the operating state (S42). With such a configuration, when the required driving force cannot be covered by only one of the motors 110 and 210, both the motors 110 and 210 are set to the operating state. For this reason, it is possible to suppress a problem in the operation of the vehicle 100 due to one of the motors 110 and 210 being stopped.

[0048] FIG. 4 is a diagram for explaining the operations and effects exhibited by the vehicle 100 according to this embodiment in comparison with a reference example. In FIG. 4, the line L1 indicates the data of the vehicle 100 according to this embodiment, and the line L2 indicates the data of the vehicle according to the reference example. The vehicle according to the reference example controls the driving force distribution of the main drive motor and the sub-drive motor so that the efficiency at that time is maximized without considering the temperature of the speed reducer (that is, without performing thermal management related to the speed reducer). According to such control, for example, the efficiency changes as indicated by the line L2 in FIG. 4. On the other hand, in the vehicle 100 (embodiment), the efficiency changes as indicated by the line L1, for example, by the above-described control (see FIGS. 2 and 3). Comparing the efficiencies of both, the line L2 is higher than the line L1 in the short term, but in the long term, the line L1 exceeds the line L2. In long-distance driving, the electricity cost of the vehicle according to the embodiment is better than that of the vehicle according to the reference example.

[0049] Note that the configuration of the vehicle is not limited to the configuration shown in FIG. 1. For example, the means for shutting off the cooling water passage is not limited to a three-way valve and can be changed as appropriate. The number of valves is also arbitrary. For example, a five-way valve, a six-way valve, an eight-way valve, a nine-way valve, or a ten-way valve may be used to reduce the number of valves.

[0050] In the configuration of FIG. 1, the front motor (motor 110) is the main drive motor and the rear motor (motor 210) is the auxiliary drive motor, but the configuration is not limited to this. FIG. 5 is a diagram showing a first modification of the configuration shown in FIG. 1. As shown in FIG. 5, the front motor (motor 110A) may be the auxiliary drive motor and the rear motor (motor 210A) may be the main drive motor. The maximum driving force of motor 210A is greater than the maximum driving force of motor 110A.

[0051] In the configuration of FIG. 1, not only the speed reducers 130 and 230 but also the motors 110 and 210 are cooled by the lubricating oil supplied from the lubricating devices 10 and 20. However, it is not limited to this, and the motors 110 and 210 may be cooled by water. FIG. 6 is a diagram showing a second modification of the configuration shown in FIG. 1. In the configuration shown in FIG. 6, the lubricating devices 10A and 20A supply lubricating oil to the speed reducers 130 and 230 through the oil circuits P1A and P2A, respectively, but do not supply lubricating oil to the motors 110 and 210. The passages P35A and P31A that constitute the cooling water passages pass through the motors 110 and 210 and the inverters 120 and 220, respectively. The cooling device 30A cools the motors 110 and 210, the inverters 120 and 220, and the power storage device 300.

[0052] The vehicle may be provided with three or more motors. The vehicle may be provided with a plurality of in-wheel motors. The vehicle may be an electric vehicle (xEV) other than a BEV. The number of wheels is also arbitrary and may be two, three, or five or more.

[0053] The processing flows F1, F3, F4, and F5 shown in FIGS. 2 and 3 can be changed as appropriate. For example, in the processing flow F5 shown in FIG. 3, S52 may be omitted. Th2 may be variable according to the required driving force. Also, in the above-described embodiment, as motor control for preferentially driving the second motor over the first motor, when stopping either the first motor or the second motor does not interfere with the operation of the vehicle, motor control for stopping the first motor is adopted. However, the present invention is not limited to this, and as motor control for preferentially driving the second motor over the first motor, motor control for biasing the driving force distribution between the driving force of the first motor and the driving force of the second motor toward the second motor side may be adopted. For example, the processing flow F1 shown in FIG. 2 may be changed so that the main drive distribution is set within a range greater than 0.0 and equal to or less than 0.3 at S23.

[0054] The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is shown not by the description of the above-described embodiments but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims be included.

Explanation of Reference Numerals

[0055] 10, 20 Lubrication device, 30 Cooling device, 100 Vehicle, 110, 210 Motor, 130, 230 Reducer, 500 Control device, P1, P2 Oil circuit, W1 to W4 Wheels.

Claims

1. A first motor that applies a driving force to a first wheel via a first speed reducer; A second motor that applies a driving force to a second wheel via a second speed reducer; A control device that controls the driving force of the first motor and the driving force of the second motor; Comprising: The maximum driving force that the first motor can output is greater than the maximum driving force that the second motor can output; When the temperature parameter correlated with the temperature of the first speed reducer and the temperature of the second speed reducer is lower than a predetermined temperature, the control device preferentially drives the second motor over the first motor. A vehicle.

2. When the control device generates a required driving force required for the vehicle by the first motor and the second motor, it determines whether a predetermined first condition is satisfied. When it is determined that the first condition is satisfied, the first motor is stopped, and the second motor is configured to generate the required driving force. The first condition is satisfied when the temperature parameter is lower than the predetermined temperature and the required driving force is less than or equal to the maximum driving force of the second motor. The vehicle according to claim 1.

3. When it is determined that the first condition is not satisfied, the control device determines whether a predetermined second condition is satisfied. When it is determined that the second condition is satisfied, the second motor is stopped, and the first motor is configured to generate the required driving force. The second condition is satisfied when the temperature parameter is lower than the predetermined temperature, and the required driving force is greater than the maximum driving force of the second motor and less than or equal to the maximum driving force of the first motor. The vehicle according to claim 2.

4. When one of the first motor and the second motor is in a stopped state and the other is in an operating state, the control device determines whether a predetermined third condition is satisfied. When it is determined that the third condition is satisfied, both the first motor and the second motor are configured to be in an operating state. The third condition is satisfied when the maximum driving force that the operating motor can output exceeds the required driving force required for the vehicle. The vehicle according to claim 3.

5. One of the first wheel and the second wheel is a front wheel of the vehicle, and the other is a rear wheel of the vehicle. The vehicle is A first oil circuit in which the lubricating oil of the first speed reducer circulates; A second oil circuit in which the lubricating oil of the second speed reducer circulates; a first temperature sensor for detecting the temperature of the lubricating oil of the first speed reducer; a second temperature sensor for detecting the temperature of the lubricating oil of the second speed reducer; a cooling device for cooling the lubricating oil of the first speed reducer and the lubricating oil of the second speed reducer; further comprising; the control device obtains the temperature parameter by using the detection result of the first temperature sensor and the detection result of the second temperature sensor; while one of the first motor and the second motor is in a stopped state and the other is in an operating state, the control device cools the lubricating oil of the first speed reducer or the second speed reducer that is mechanically connected to the operating motor by the cooling device, and the lubricating oil of the second speed reducer or the first speed reducer that is mechanically connected to the stopped motor is not cooled by the cooling device. The vehicle according to any one of claims 1 to 4, wherein the cooling device is controlled.

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