Vehicle

Abstract

The invention provides a vehicle. A vehicle is provided with a first electric motor that applies driving force to a first wheel via a first speed reducer, a second electric motor that applies driving force to a second wheel via a second speed reducer, and a control device that controls the driving force of the first electric motor and the driving force of the second electric motor. The maximum driving force that can be output by the first motor is greater than the maximum driving force that can be output by the second motor. When a temperature parameter relating to 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 than the first motor.

Description

Technical Field

[0001] The present disclosure relates to a vehicle having a plurality of electric motors. Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2012 - 034433 relates to a vehicle having a first electric motor and a second electric motor. The following technique is disclosed in Japanese Unexamined Patent Application Publication No. 2012 - 034433: When the output required for the vehicle (required driving force) is equal to or less than the allowable output of the smaller one of the allowable outputs of the first electric motor and the second electric motor, the motor on the lower temperature side among the first electric motor and the second electric motor is selected and operated. In this technique, when the temperature difference between the first electric motor and the second electric motor does not reach a specified value, switching from the first electric motor to the second electric motor or switching from the second electric motor to the first electric motor is prohibited. Summary of the Invention

[0003] According to the above technique, by driving only the motor on the lower temperature side among the first electric motor and the second electric motor, the temperature difference between the first electric motor and the second electric motor can be reduced. However, from the viewpoint of energy efficiency, it is not necessarily preferable to stop the motor on the higher temperature side and drive only with the motor on the lower temperature side. In addition, in Japanese Unexamined Patent Application Publication No. 2012 - 034433, how to control each electric motor when the temperatures of both the first electric motor and the second electric motor become low is not mentioned. In a vehicle in which an electric motor applies a driving force to a wheel via a speed reducer, if the temperature of the speed reducer is too low, there is a tendency for energy loss to increase.

[0004] The present disclosure has been made to solve the above problems, and an object thereof is to improve energy efficiency in a vehicle having a plurality of electric motors.

[0005] According to one aspect of the present disclosure, a vehicle having the following structure is provided.

[0006] The vehicle includes: a first electric motor that applies a driving force to a first wheel via a first speed reducer; a second electric 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 electric motor and the driving force of the second electric motor.

[0007] The maximum driving force that the first electric motor can output is greater than the maximum driving force that the second electric motor can output.

[0008] When a temperature parameter related to the temperature of the first speed reducer and the temperature of the second speed reducer is lower than a specified temperature, the control device preferentially drives the second electric motor compared to the first electric motor.

[0009] According to the present disclosure, in a vehicle having a plurality of electric motors, improvement in energy efficiency can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Hereinafter, features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described with reference to the drawings, in which like reference numerals denote like components, wherein: Figure 1 is a diagram showing a schematic structure of a vehicle according to an embodiment of the present disclosure; Figure 2 is a diagram for explaining the control of a first electric motor according to the present embodiment; Figure 3 is a diagram for explaining the control of a second electric motor according to the present embodiment; Figure 4 is a diagram for explaining actions and effects achieved by the vehicle according to the present embodiment in comparison with a reference example; Figure 5 is showing Figure 1 a first modification of the structure of the vehicle shown in; and Figure 6 is showing Figure 1 a second modification of the structure of the vehicle shown in. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0011] 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.

[0012] Figure 1 is a diagram showing a schematic structure of a vehicle according to the present embodiment. Referring to Figure 1 , the vehicle 100 includes electric motors 110, 210, inverters 120, 220, speed reducers 130, 230, axles 140, 240, a power storage device 300, lubrication devices 10, 20, a cooling device 30, heat exchangers 41, 42, a control device 500, and wheels W1 to W4. The cooling device 30 is configured to be able to perform heat exchange with the lubrication devices 10, 20, respectively. The cooling device 30 is configured to cool the inverters 120, 220, and the power storage device 300. The control device 500 is configured to control the inverters 120, 220, the lubrication devices 10, 20, and the cooling device 30. The vehicle 100 is, for example, a four-wheel BEV (battery electric vehicle) configured to be able to drive using electric power output from the power storage device 300.

[0013] The wheels W1, W2, the motor 110, the speed reducer 130, and the axle 140 are arranged at the front part of the vehicle 100. The wheel W1 is mounted at one end of the axle 140, and the wheel W2 is mounted at the other end. The wheels W1 and W2 corresponding to the front wheels of the vehicle 100 are respectively an example of the "first wheels" of 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, W2) via the speed reducer 130.

[0014] The inverter 120 functions as a PCU (Power Control Unit) for the motor 110. The inverter 120 uses the power supplied from the power storage device 300 to generate the driving power for the motor 110. 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, W2) via the speed reducer 130.

[0015] The lubrication device 10 includes an oil circuit P1 (first oil circuit) for circulating the lubricating oil of the speed reducer 130, 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 the 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 using the lubricating oil. Such a cooling method can directly supply oil to the heat generating part for cooling, so 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.

[0016] 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. The wheel W3 is mounted at one end of the axle 240, and the wheel W4 is mounted at the other end. The wheels W3 and W4 corresponding to the rear wheels of the vehicle 100 are respectively an example of the "second wheels" of 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.

[0017] The inverter 220 functions as a PCU (Power Control Unit) for the motor 210. The inverter 220 uses the power supplied from the power storage device 300 to generate drive power for the motor 210. The motor 210 is driven by the inverter 220 to rotate the wheels W3 and W4. The torque output by the motor 210 is transmitted to the axle 240 (and further to the wheels W3 and W4) via the speed reducer 230.

[0018] The lubrication device 20 includes an oil circuit P2 (second oil circuit) for circulating the lubricating oil of the speed reducer 230, 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 using the lubricating oil. Such a cooling method can directly supply oil to the heat generating part for cooling, so the cooling effect is high. 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.

[0019] 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 a cooling medium flows. The pump 33 is configured to receive the cooling medium from the passage P35 and deliver the cooling medium to the passage P31. The cooling medium flowing in the passages P35 and P31 exchanges heat with the inverters 120 and 220, respectively. Thereby, the inverters 120 and 220 are cooled. In addition, the cooling medium flowing in 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 cooling medium and outputs the detection result to the control device 500. In this embodiment, water is used as the cooling medium, and a water pump is used as the pump 33. However, the type of the cooling medium can be appropriately changed. The cooling medium is not limited to a liquid and can also be a gas. The cooling device 30 can also be configured to be able to adjust the temperature of the cooling medium. The cooling device 30 can also be configured to be able to exchange heat with the refrigeration cycle of the air conditioning device, for example.

[0020] The first port (inlet) of the three ports of the three-way valve 32 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 either the second port or the third port designated 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.

[0021] The first port (inlet) of the three ports of the three-way valve 31 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 either the second port or the third port designated 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.

[0022] 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. Regarding the sensitivity to loss with respect to rotational speed, the motor 210 is smaller than the motor 110. The control device 500 controls the driving forces of the motors 110 and 210. The control device 500 can independently vary the outputs of the motors 110 and 210 through the inverters 120 and 220.

[0023] Figure 2 It is a diagram for explaining the first motor control executed by the control device 500. Refer to Figure 2 , the vehicle 100 further includes an HMI (Human Machine Interface). The HMI 600 includes, for example, an input device and a display device. The HMI 600 may also include an operation unit (for example, an accelerator pedal, a brake pedal, and a steering wheel) used by the user to request acceleration, deceleration, and steering of the vehicle 100 (control device 500). In addition, various sensors (not shown) are mounted on the vehicle 100. The in-vehicle sensors may also include, for example, sensors for detecting the states of the motors 110 and 210 and sensors for detecting the input power and output power of the inverters 120 and 220.

[0024] The control device 500 includes a processor 510 and a storage device 520. The storage device 520 is configured to be able to store the accommodated information. In the storage device 520, in addition to storing programs, various information used in the programs is also stored. In this embodiment, by the processor 510 executing the program stored in the storage device 520, the control described below, for example, is executed. However, these controls can also be executed only by hardware (electronic circuit) without using software.

[0025] The control device 500 executes Figure 2 and the following Figure 3 each processing flow shown in the flowchart. "S" in the flowchart refers to 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 "0", for example.

[0026] The control device 500 starts the processing flow F1, for example, triggered by the startup of the control system of the vehicle 100 (including the control device 500). In S11, the control device 500 calculates the required driving force required by the vehicle 100. In the vehicle 100 during manual driving, the control device 500 can also calculate the required driving force based on the state of the vehicle 100 (vehicle speed, load, etc.) and the driving requirements from the user (accelerator operation amount, brake operation amount, steering angle, etc.), for example. In addition, the vehicle 100 can also be configured to be able to drive autonomously. The vehicle 100 can also be equipped with a camera and / or radar for recognizing the surrounding conditions. In the vehicle 100 during autonomous driving, the control device 500 can also calculate the required driving force based on the state of the vehicle 100 and the surrounding conditions of the vehicle 100 (pedestrians, other vehicles, road gradient, road signs, traffic lights, etc.), for example.

[0027] In the next S12, the control device 500 determines whether the flag FG is "0". In the initial stage, 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 by driving the motors 110 and 210 to generate the required driving force calculated in S11.

[0028] Specifically, the control device 500 controls the driving force of the motor 110 and the driving force of the motor 210 such that the total value of the driving forces applied to all the drive wheels (wheels W1 to W4) of the vehicle 100 approaches the required driving force. At this time, the control device 500 may also 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) in such a way that the difference in the temperature of the lubricating oil of the speed reducer 130 and the temperature of the lubricating oil of the speed reducer 230 becomes smaller. The driving force distribution is represented, for example, by 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 expressed by an equation such as "main drive distribution = driving force of main drive motor / total driving force". In the control of S13, the larger the main drive distribution, the easier it is for the temperature of the lubricating oil of the speed reducer 130 to become higher, and the easier it is for the temperature of the lubricating oil of the speed reducer 230 to become lower. 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, by increasing the main drive distribution, the temperature difference between the two is likely to become smaller. 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, by decreasing the main drive distribution, the temperature difference between the two is likely to become smaller. 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.

[0029] In the following S21, the control device 500 determines whether a temperature parameter related to the temperature of the speed reducer 130 and the temperature of the speed reducer 230 (hereinafter referred to as "To") is lower than a specified temperature (hereinafter referred to as "Th1"). The main body of the speed reducer 130 exchanges heat with the lubricating oil flowing in the oil circuit P1. Therefore, the temperature of the speed reducer 130 is related to the temperature of the lubricating oil of the speed reducer 130. The main body of the speed reducer 230 exchanges heat with the lubricating oil flowing in the oil circuit P2. Therefore, the temperature of the speed reducer 230 is related to the temperature of the lubricating oil of the speed reducer 230. In this embodiment, the average value of the temperature of the lubricating oil of the speed reducer 130 (the first oil temperature) detected by the temperature sensor 12 and the temperature of the lubricating oil of the speed reducer 230 (the second oil temperature) detected by the temperature sensor 22 is set as To. However, it is not limited thereto, and the sum value of the first oil temperature and the second oil temperature may be used as To. In addition, the lower temperature or the higher temperature of the first oil temperature and the second oil temperature may be used as To. Th1 may also 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 greater viscosity as the temperature becomes lower. Moreover, if the temperature of the lubricating oil of the speed reducer is too low, the loss of the speed reducer tends to increase due to the increase in the viscosity of the lubricating oil. Th1 may also be the boundary temperature at which the viscosity of the lubricating oil is larger than the appropriate range.

[0030] When To is lower than Th1 (S21: Yes), 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. When the required driving force is less than or equal to the maximum driving force of the motor 210 (S22: Yes), 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 driving force distribution (main: sub) becomes "0:10". The control device 500 stops the motor 110 according to this main drive distribution and generates the required driving force through the motor 210. Thereby, the driving mode is changed from 4WD to two-wheel drive (2WD). The required driving force being 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.

[0031] 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 equal to or less than the maximum driving force of the motor 110. When the required driving force is equal to or less than 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 the flag FG to "2". 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 according to this main drive distribution and generates the required driving force through the motor 110. Thus, the driving mode changes from 4WD to 2WD.

[0032] After executing the process of S23 or S25, the process returns to the initial 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 to generate the required driving force calculated in S11 through the working motor (either the motor 110 or 210). Two-wheel drive (2WD) is performed by the working motor. The working 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", S11, S12, and S14 are repeated.

[0033] When To is equal to or greater than Th1 (No in S21), the process also 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 also 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.

[0034] The control device 500 executes Figure 2 the processing flow F3 shown Figure 3 in parallel with the processing flow F1 shown. For example, when the control system of the vehicle 100 is started, the processing flow F3 starts together with the processing flow F1. Figure 3 This is a diagram for explaining the second motor control executed by the control device 500.

[0035] Referring to Figure 3 , in S31, the control device 500 determines whether 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 the working state (refer toFigure 2 of S13). In S32, the control device 500 controls Figure 1 the cooling device 30 shown in FIG. to cool 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, respectively. In S32, the pumps 11, 21, and 33 are all in the operating state.

[0036] Specifically, the control device 500 controls the three-way valves 31 and 32 so that the passage P31 is connected to the passage P32, and the passage P33 is connected to the passage P34. Then, in this state, the control device 500 controls the pump 33 so that the cooling medium (cooling water) flows through the passages P31, P32, P33, P34, and P35 in sequence. Through the heat exchanger 41, the lubricating oil of the speed reducer 130 flowing in the oil circuit P1 exchanges heat with the cooling medium (cooling water) flowing in the passage P34. The lubricating oil of the speed reducer 130 is cooled by this heat exchange. In addition, through the heat exchanger 42, the lubricating oil of the speed reducer 230 flowing in the oil circuit P2 exchanges heat with the cooling medium (cooling water) flowing in the passage P32. The lubricating oil of the speed reducer 230 is cooled by this heat exchange. After the process of S32 is executed, the process returns to the initial step (S31). During the period when the flag FG is "0", the cooling of the lubricating oil of each speed reducer by the cooling device 30 is continuously executed (S32).

[0037] In the processing flow F1 ( Figure 2 ) executed in parallel with the processing flow F3, when the flag FG is not "0" by executing the processing of 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 Figure 1 the cooling device 30 shown in FIG. 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 following-described cooling control is executed. Thus, it is possible to suppress the excessive rise in the temperature of the lubricating oil of the speed reducer mechanically connected to the operating motor, 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 structure, it is easy to appropriately execute the thermal management of the front and rear parts of the vehicle 100, respectively.

[0038] For example, when the flag FG is "1", the motor 210 (slave drive motor) becomes operational, and the motor 110 (main drive motor) becomes stopped. In this case, the control device 500 controls the three-way valves 31 and 32 in S33 to connect the passage P31 and the passage P32, and connect the passage P33 and the passage P34a. In this state, the control device 500 drives the pump 33. In this case, the cooling medium (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 cooling medium (cooling water). In addition, the control device 500 stops the pump 11. Thereby, the power consumption is reduced.

[0039] In addition, when the flag FG is "2", the motor 110 (main drive motor) becomes operational, and the motor 210 (slave drive motor) becomes stopped. In this case, the control device 500 controls the three-way valves 31 and 32 in S33 to connect the passage P31 and the passage P32a, and connect the passage P33 and the passage P34. In this state, the control device 500 drives the pump 33. In this case, the cooling medium (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 cooling medium (cooling water). In addition, the control device 500 stops the pump 21. Thereby, the power consumption is reduced.

[0040] When the flag FG is not "0", the control device 500 executes the above cooling control (S33). Next, in S34, the control device 500 determines 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.

[0041] In the processing flow F4, the control device 500 determines in S41 whether the latest required driving force calculated in Figure 2 S11 is greater than the maximum driving force of the operating motor. When the required driving force is greater than the maximum driving force of the operating motor (Yes in S41), the control device 500 sets the flag FG to "0" in S42. Thereby, the setting of the driving force distribution is cancelled, and it is determined as "Yes" in Figure 2 S12. Then, in S13, both the motors 110 and 210 become operational. The required driving force exceeding the maximum driving force of the operating motor means that the required driving force cannot be output only by the operating motor.

[0042] When the process of S42 is executed, the process flow F4 ends. When the required driving force does not exceed the maximum driving force of the motor in operation (No in S41), the process of S42 is not executed. In this case, the flag FG remains "1" or "2", and the process flow F4 ends.

[0043] In the process flow F5, the control device 500 determines in S51 whether the above-mentioned To is higher than a specified temperature (hereinafter referred to as "Th2"). Th2 can 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 ( Figure 2 in S14). Thus, compared with the case where the required driving force is generated by two motors, the motor in operation is likely to heat up, and the temperature of the speed reducer mechanically connected to the motor in operation is likely to rise. In addition, by cutting off the motor that has stopped and the cooling water path for cooling the speed reducer (refer to S33), the temperature of the speed reducer mechanically connected to the stopped motor is also likely to rise. Therefore, To rises. If To is higher than Th2 (Yes in S51), the process proceeds to S52.

[0044] In S52, the control device 500 determines whether the latest required driving force calculated in Figure 2 in S11 is greater than a specified value (hereinafter referred to as "Th3"). Th3 is less than the maximum driving force of the motor 210. Th3 can be the boundary value of the recommended range where the required driving force is greater than 2WD. When the required driving force is greater than Th3 (Yes in S52), the control device 500 sets the flag FG to "0" in S53. Thus, the setting of the driving force distribution is released, and it is determined as Yes in Figure 2 in S12. Then, in S13, both the motor 110 and 210 become the operating state. After the process of S53 is executed, the process flow F5 ends.

[0045] When it is determined as No in S51 or S52, the process of S53 is not executed, and the process flow F5 ends. In S34, when both the process flows F4 and F5 are executed, the process returns to S31. In this way, the process flow F3 is repeatedly executed.

[0046] As described above, the motor control method of this embodiment includes the processes of the process flows F1, F3, F4, and F5. When the temperature parameter (To) related to the temperature of the speed reducer 130 (first speed reducer) and the temperature of the speed reducer 230 (second speed reducer) is lower than the specified temperature, the control device 500 preferentially drives the motor 210 (second motor) compared with the motor 110 (first motor) ( Figure 2of S21 to S25). When To becomes low, it is presumed that the temperatures of the speed reducers 130 and 230 are low. In such a case, by preferentially driving the motor 210 compared to the motor 110, the temperature of the speed reducer 230 can be increased. The control device 500 obtains To using the detection results of the temperature sensors 12 and 22 respectively. With such a structure, it is easy to manage the lubricating oil of the speed reducer at an appropriate temperature. Thus, by suppressing the temperature of the speed reducer (such as the temperature of the lubricating oil) from becoming too low, an increase in losses can be suppressed. Moreover, compared with driving the motor 110 with a large maximum driving force, the heat generation efficiency (the efficiency of converting electric power into heat) of driving the motor 210 with a small maximum driving force is higher. In addition, compared with the motor 110, the motor 210 tends to have less loss. Therefore, compared with driving the motor 110, the power consumption economy (power consumption rate) of driving the motor 210 is better. According to the above structure, preheating can be achieved without using additional energy. Therefore, the energy efficiency can be improved in the vehicle 100 equipped with multiple motors.

[0047] When the control device 500 generates the required driving force required by the vehicle 100 by the motors 110 and 210, it determines whether a specified first condition is satisfied ( Figure 2 of S21, S22). The first condition is satisfied when the temperature parameter (To) is lower than the specified temperature (Th1) and the required driving force is less than or equal to the maximum driving force of the motor 210. When it is determined that the first condition is satisfied (both S21 and S22 are "yes"), the control device 500 stops the motor 110 and generates the required driving force by the motor 210 ( Figure 2 of S23). By stopping the motor 110, the power consumption can be reduced. In addition, it can be considered that if the required driving force is less than or equal to the maximum driving force of the motor 210, stopping the motor 110 will not cause an obstacle to driving. According to the above structure, it is possible to suppress an obstacle to the driving of the vehicle and suppress an increase in losses caused by an excessive decrease in the temperature of the speed reducer.

[0048] When the control device 500 determines that the above first condition is not satisfied (in Figure 2 S22 is "no"), it determines whether a specified second condition is satisfied ( Figure 2 of S24). The second condition is satisfied when the temperature parameter (To) is lower than the specified temperature (Th1), the required driving force is greater than the maximum driving force of the motor 210, and less than or equal to the maximum driving force of the motor 110. When it is determined that the second condition is satisfied (S21 is "yes", S22 is "no", and S24 is "yes"), the control device 500 stops the motor 210 and generates the required driving force by the motor 110 ( Figure 2S25). 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 the increase in losses. In addition, by stopping the motor 210, the power consumption can be reduced. Moreover, it is considered that if the required driving force is equal to or less than the maximum driving force of the motor 110, even if the motor 210 is stopped, it will not hinder the driving of the vehicle 100.

[0049] When one of the motors 110 and 210 is in a stopped state and the other is in an operating state, the control device 500 determines whether a specified third condition is satisfied ( Figure 3 S34). The third condition is satisfied when the required driving force required for the vehicle 100 exceeds the maximum driving force that the operating motor can output. When it is determined that the third condition is satisfied (Yes in S41), the control device 500 causes both the motors 110 and 210 to be in an operating state (S42). In such a configuration, if the required driving force cannot be provided by only one of the motors 110 and 210, both the motors 110 and 210 are in an operating state. Therefore, it is possible to suppress the driving of the vehicle 100 from being hindered due to the stop of one of the motors 110 and 210.

[0050] Figure 4 FIG. is a diagram for explaining the functions and effects achieved by the vehicle 100 of this embodiment in comparison with the reference example. In Figure 4 , the line L1 represents the data of the vehicle 100 of this embodiment, and the line L2 represents the data of the vehicle of the reference example. The vehicle of the reference example controls the driving force distribution of the main drive motor and the sub-drive motor in such a way that the efficiency at that time is maximized without considering the temperature of the speed reducer (i.e., without performing heat management related to the speed reducer). According to such control, for example, as shown by the line L2 in Figure 4 , the efficiency changes. On the other hand, in the vehicle 100 (embodiment), through the above-described control (see Figure 2 and Figure 3 ), the efficiency changes as shown by the line L1, for example. If the efficiencies of both are compared, 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 power consumption economy of the vehicle of the embodiment is superior to that of the vehicle of the reference example.

[0051] In addition, the structure of the vehicle is not limited to the structure shown in Figure 1 . For example, the means for cutting off the cooling water passage is not limited to the three-way valve and can be appropriately changed. 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 can also be used to reduce the number of valves.

[0052] In Figure 1In the structure, the front motor (motor 110) is used as the main drive motor, and the rear motor (motor 210) is used as the slave drive motor, but the structure is not limited to this. Figure 5 is a diagram showing Figure 1 a first modification example of the structure shown in. As Figure 5 shown, the front motor (motor 110A) can also be used as the slave drive motor, and the rear motor (motor 210A) can be used as the main drive motor. The maximum driving force of motor 210A is greater than the maximum driving force of motor 110A.

[0053] In Figure 1 the structure, 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 can also be cooled by water. Figure 6 is a diagram showing Figure 1 a second modification example of the structure shown in. In Figure 6 the structure shown, 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 constituting the cooling water circuit 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.

[0054] The vehicle can also be equipped with more than three motors. The vehicle can also be equipped with multiple in-wheel motors. The vehicle can be an electric vehicle (EV) other than a BEV. The number of wheels is also arbitrary, and can be two, three, or more than five.

[0055] Figure 2 and Figure 3 the processing flows F1, F3, F4, and F5 shown can be appropriately changed. For example, in Figure 3 the processing flow F5 shown, S52 can also be omitted. Th2 can also be variable according to the required driving force. In addition, in the above embodiment, as the motor control for preferentially driving the second motor compared to the first motor, the motor control of stopping the first motor when stopping either the first motor or the second motor does not hinder the driving of the vehicle is adopted. However, it is not limited to this, and as the motor control for preferentially driving the second motor compared to the first motor, the motor control of making the driving force distribution of the driving force of the first motor and the driving force of the second motor bias toward the second motor side can also be adopted. For example, Figure 2 the processing flow F1 shown can also 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 in S23.

[0056] The embodiments disclosed herein should be considered illustrative in all respects and not restrictive. The scope of the present invention is shown not by the description of the above embodiments but by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. A vehicle, wherein, the vehicle includes: a first motor that applies driving force to a first wheel via a first speed reducer; a second motor that applies 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 related to the temperature of the first speed reducer and the temperature of the second speed reducer is lower than a specified temperature, the control device preferentially drives the second motor compared to the first motor.

2. The vehicle according to claim 1, wherein, the control device is configured to, when the required driving force required by the vehicle is generated by the first motor and the second motor, determine whether a specified first condition is satisfied, when it is determined that the first condition is satisfied, stop the first motor and generate the required driving force by the second motor, the first condition is satisfied when the temperature parameter is lower than the specified temperature and the required driving force is less than or equal to the maximum driving force of the second motor.

3. The vehicle according to claim 2, wherein, the control device is configured to, when it is determined that the first condition is not satisfied, determine whether a specified second condition is satisfied, when it is determined that the second condition is satisfied, stop the second motor and generate the required driving force by the first motor, the second condition is satisfied when the temperature parameter is lower than the specified temperature, 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.

4. The vehicle according to claim 3, wherein, the control device is configured to, when one of the first motor and the second motor is in a stopped state and the other is in an operating state, determine whether a specified third condition is satisfied, when it is determined that the third condition is satisfied, make both the first motor and the second motor operate, the third condition is satisfied when the required driving force required by the vehicle exceeds the maximum driving force that the operating motor can output.

5. The vehicle according to any one of claims 1 to 4, wherein, 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 further includes: a first oil circuit for circulating lubricating oil of the first speed reducer; a second oil circuit for circulating lubricating oil of the second speed reducer; 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; and a cooling device for cooling the lubricating oil of the first speed reducer and the lubricating oil of the second speed reducer, the control device obtains the temperature parameter using the detection result of the first temperature sensor and the detection result of the second temperature sensor, The control device controls the cooling device in such a manner that during a period in which one of the first motor and the second motor is in a stopped state and the other is in an operating state, the lubricating oil of the first speed reducer or the second speed reducer that is mechanically connected to the operating motor is cooled 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.

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