Cooling control device for electric vehicle

Abstract

The present invention relates to a cooling control device for an electric vehicle, which is provided with a first electric oil pump for supplying oil to a first motor for driving front wheels and a second electric oil pump for supplying oil to a second motor for driving rear wheels, and which is capable of switching between a four-wheel drive travel mode and a two-wheel drive travel mode using the second motor as a driving force source. The cooling control device for the electric vehicle drives only the second electric oil pump when the two-wheel drive travel mode is selected, and starts the operation of the first electric oil pump when it is predicted that the electric vehicle travels in the four-wheel drive travel mode.

Description

Technical Field

[0001] The present invention relates to a control device for cooling an electric motor or the like in a vehicle having an electric motor as a driving force source, and more particularly to a cooling control device for cooling using oil. Background Art

[0002] Japanese Patent Application Laid-Open No. 2001-112114 describes a control device for a four-wheel drive vehicle, which includes a front motor as a driving force source for a pair of front wheels, and a rear motor as a driving force source for a pair of rear wheels and having a smaller thermal rating or cooling performance than the front motor. The control device is configured to maintain the driving force required by the vehicle by increasing the output of the front motor when the operation of the rear motor is restricted, and to ensure driving stability by reducing the output of the rear motor when the operation of the front motor is restricted, thereby setting the distribution ratio of the torque of the front and rear wheels to a desired distribution ratio.

[0003] In addition, Japanese Patent Application Laid-Open No. 2014-000848 describes a hybrid electric vehicle having an engine and a motor as a driving force source, and capable of setting an HV driving mode for driving the engine and an EV driving mode for driving the motor while stopping the engine. In addition, the hybrid electric vehicle has a mechanical oil pump driven by the power of the engine and an electric oil pump driven by the electric motor in parallel, and when the viscosity of the refrigerant discharged by these oil pumps is high, only the oil pump with a higher discharge force of the mechanical oil pump and the electric oil pump is driven, and when the viscosity of the refrigerant is low, only the other oil pump is driven.

[0004] The four-wheel drive vehicle described in Japanese Patent Publication No. 2001-112114 can independently drive a pair of front wheels and a pair of rear wheels, so if only one driving force source is driven, two-wheel drive can be performed. In addition, since there are multiple driving force sources, in order to ensure the cooling performance of the driving force source during four-wheel drive, it is considered to set multiple cooling oil pumps or set a large oil pump. In the case of multiple oil pumps and large oil pumps, if each oil pump is driven during two-wheel drive, the electricity and power used to drive the oil pump will be lost, and the energy efficiency of the vehicle as a whole may be reduced. Summary of the invention

[0005] The present invention has been made in view of the above-mentioned technical problems, and an object of the present invention is to provide a control device for a four-wheel drive vehicle that can suppress a decrease in cooling performance of a driving force source and improve energy efficiency.

[0006] In order to achieve the above-mentioned object, the present invention provides a cooling control device for an electric vehicle, the electric vehicle comprising: a first motor, the first motor driving a first drive wheel, the first drive wheel being a wheel of one of the front wheels and the rear wheels; a first electric oil pump, the first electric oil pump supplies oil to the first motor; a second motor, the second motor driving a second drive wheel, the second drive wheel being a wheel of the other of the front wheels and the rear wheels; a second electric oil pump, the second electric oil pump supplies the oil to the second motor; a first drive unit, the first drive unit transmitting torque from the first motor to the first drive wheel; a second drive unit, the second drive unit transmitting torque from the second motor to the second drive wheel; and a mechanical oil pump, the mechanical oil pump supplying oil to the first drive wheel by operating the first drive unit The oil is supplied to the driving part, and the electric vehicle can switch between a four-wheel drive driving mode with the first motor and the second motor as the driving force source and a two-wheel drive driving mode with the second motor as the driving force source. The cooling control device of the electric vehicle is characterized in that it includes a controller, and the controller controls the first electric oil pump and the second electric oil pump. The controller includes: a pump selection part, and the pump selection part only drives the second electric oil pump of the first electric oil pump and the second electric oil pump when the two-wheel drive driving mode is selected; a prediction part, and the prediction part predicts the situation of driving in the four-wheel drive driving mode; and a starting control part, and the starting control part starts the first electric oil pump when the prediction part predicts the situation of driving in the four-wheel drive driving mode.

[0007] In the present invention, a mode selection unit operated by a driver to select the four-wheel drive travel mode may be provided, and the prediction unit may predict travel in the four-wheel drive travel mode based on whether the mode selection unit is operated.

[0008] In the present invention, it may also be that the higher the temperature of the first motor, the more the controller increases the supply amount of the oil based on the first electric oil pump relative to the oil of the first motor, and the higher the temperature of the second motor, the more the controller increases the supply amount of the oil based on the second electric oil pump relative to the oil of the second motor.

[0009] In the present invention, the four-wheel drive driving mode may also include multiple driving modes, and the controller controls the supply amount of the oil based on the first electric oil pump relative to the oil of the first motor and the supply amount of the oil based on the second electric oil pump relative to the oil of the second motor according to the multiple driving modes.

[0010] In the present invention, the four-wheel drive driving mode may also include at least any one of a tracking mode, a drift mode, a sports mode and a manual gear mode, the tracking mode is a mode that improves cornering performance compared to the two-wheel drive driving mode, the drift mode is a mode that improves driving accuracy, the sports mode is a mode that improves acceleration performance or power performance, and the manual gear mode is a mode that controls the driving torque of the first motor and the second motor based on the driving characteristics corresponding to the driver's gear shifting operation.

[0011] According to the present invention, a first motor driving a first driving wheel and a second motor driving a second driving wheel are provided, wherein the first driving wheel is a wheel of one of the front wheels and the rear wheels, and the second driving wheel is a wheel of the other party, and when a two-wheel drive driving mode is set, the second motor is used as a driving force source. That is, since the first motor is not energized, the first motor does not generate heat and does not require cooling. Therefore, by stopping or maintaining a stopped state of the first electric oil pump corresponding to the first motor, the power consumption of the electric vehicle as a whole can be reduced. That is, the reduction in the cooling performance of the second motor that becomes the driving force source in the two-wheel drive driving mode can be suppressed, and energy efficiency can be improved. In other words, by providing a first electric oil pump that only supplies oil to the first motor that stops when driving in the two-wheel drive driving mode, the second electric oil pump corresponding to the second motor can be used as long as it has a function to the extent that the second motor can be cooled, so the second electric oil pump can be miniaturized.

[0012] In addition, when the vehicle is traveling in the two-wheel drive driving mode, the first drive unit also rotates at a rotation speed corresponding to the vehicle speed by the rotation of the first drive wheel. That is, the mechanical oil pump is working. Therefore, oil is supplied to the lubricating part of the first drive unit, so that the durability reduction of the first drive unit can be suppressed. In other words, since oil is only supplied to the part to which oil should be supplied, the power loss for driving the mechanical oil pump can be reduced.

[0013] Furthermore, when it is predicted that the vehicle will travel in the four-wheel drive mode, the stopped first electric oil pump is activated, so that oil can be supplied to the first motor for cooling before the first motor is energized to generate electricity. As a result, the first electric oil pump can be activated in advance when the vehicle travels in the four-wheel drive mode, thereby suppressing a decrease in the cooling performance of the first motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like parts, and in which:

[0015] Figure 11 is a block diagram schematically showing a drive system of a four-wheel independent drive vehicle in an embodiment of the present invention.

[0016] Figure 2 It is a schematic diagram showing an example of a drive unit on the rear wheel side.

[0017] Figure 3 This is a schematic diagram showing an example of a drive unit on the front wheel side.

[0018] Figure 4 : is a diagram schematically showing a required driving torque map used in the D range.

[0019] Figure 5 : is a line diagram schematically showing a required drive torque map when the accelerator opening is 50% in the D range to the L range.

[0020] Figure 6 FIG. 1 is a diagram showing an example of a shift device in which a shift position is selected by operating a shift lever.

[0021] Figure 7 FIG. 1 is a diagram showing an example of a shift device in which a shift position is selected by operating a paddle switch.

[0022] Figure 8 This is a flowchart for explaining an example of control for determining whether or not to switch the shift position.

[0023] Fig. 9 is a block diagram illustrating the input and output signals of the controller.

[0024] Fig.10 is a block diagram showing the functional structure of the controller.

[0025] Fig.11 This is a flowchart for explaining an example of control executed in the embodiment of the present invention.

[0026] Fig.12 This is a diagram showing an example of a map that determines the rotation speed of the oil pump for each running mode. DETAILED DESCRIPTION

[0027] Next, an embodiment of the present invention will be described with reference to the drawings. The embodiment described below is merely an example of a case where the present invention is implemented, and does not limit the present invention.

[0028] The electric vehicle used as the object of the present invention is a vehicle having a total of four wheels, namely, two front wheels and two rear wheels, and is an electric vehicle in which the two front wheels and the two rear wheels are respectively provided with motors as driving force sources and can drive the two front wheels and the two rear wheels independently of each other. In addition, the two front wheels may be connected to the driving force source for the front wheels via an appropriate differential mechanism, and the two rear wheels may be connected to the driving force source for the rear wheels via another appropriate differential mechanism. Moreover, the electric vehicle used as the object of the present invention may also be an electric vehicle configured to have motors as driving force sources corresponding to the front and rear four wheels, respectively, and can control the driving torque and regenerative braking torque (regenerative torque) of each of the four wheels independently of each other.

[0029] exist Figure 1 Schematically shows an example of a four-wheel independent drive vehicle that is configured to independently drive all four wheels in addition to being able to independently control the driving torque or regenerative braking torque of the front and rear wheels. The electric vehicle (hereinafter referred to as the vehicle) Ve shown here has left and right front wheels 1r, 11 and left and right rear wheels 2r, 21, and drive units Pf, Pr as drive power sources are respectively provided corresponding to the front wheels 1r, 11 and the rear wheels 2r, 21. These drive units Pf, Pr are respectively configured with a motor and a gear reduction mechanism (transmission mechanism) as the main body.

[0030] exist Figure 2 An example of a drive unit Pr on the rear wheel 2r, 21 side is shown in a schematic diagram. The drive unit Pr is composed of a pair of drive systems that independently control the left and right rear wheels 2r, 21. These drive systems are bilaterally symmetrical structures, so they are not specifically described as "right" or "left" but are described uniformly. In addition, in the following description, when the suffix (suffix) in the figure mark is 1 character, "f" means for the front wheel, "l" means for the left wheel, and "r" means for the right wheel or the rear wheel. In the case of 2 characters, the first character "f" means for the front wheel, "r" means for the rear wheel, the second character "r" means for the right wheel, and "l" means for the left wheel.

[0031] In the drive unit Pr of the rear wheels 2r, 2l, the motors Mrr, Mrl are mounted with their rotation center axes oriented in the front-rear direction of the vehicle Ve, and drive gears 3rr, 3rl are mounted on their rotor shafts, and the drive gears 3rr, 3rl mesh with counter driven gears 4rr, 4rl. The counter driven gears 4rr, 4rl are larger in diameter than the drive gears 3rr, 3rl, so these gear pairs constitute a speed reduction mechanism. Counter drive gears 5rr, 5rl, which are bevel gears, are provided on the same axis as the counter driven gears 4rr, 4rl so as to rotate integrally, and the counter drive gears 5rr, 5rl mesh with driven gears 7rr, 7rl, which are bevel gears integrally connected to the drive shafts 6rr, 6rl connected to the rear wheels 2r, 2l. By setting the driven gears 7rr, 7rl to have a larger diameter than the counter drive gears 5rr, 5rl, these gear pairs can be used as a speed reduction mechanism.

[0032] These rear wheels 2r, 2l are equivalent to the "second drive wheel" in the embodiment of the present invention, these motors Mrr, Mrl are equivalent to the "second motor" in the embodiment of the present invention, and the part that transmits torque from these motors Mrr, Mrl to the rear wheels 2r, 2l is equivalent to the "second drive unit" in the embodiment of the present invention.

[0033] These motors Mrr, Mrl, the speed reduction mechanism and the bevel gears are accommodated in the housing 8 in a liquid-tight state. Electric oil pumps OPrr, OPrl are provided to supply oil for cooling and lubrication to the motors Mrr, Mrl inside the housing 8. In addition, the oil pumps on the rear wheels 2r, 2l side may also be a single oil pump that supplies oil 10r to the left and right motors Mrr, Mrl at the same time. These oil pumps OPrr, OPrl are provided at appropriate locations of the vehicle Ve outside the housing 8, and are configured to draw oil 10r from the oil reservoir 9r and supply oil 10r to the motors Mrr, Mrl via cooling oil passages 11rr, 11rl provided through the housing 8.

[0034] Although not particularly shown, the oil 10r is configured to flow back from the inside of the housing 8 to the oil reservoir 9r. In addition, an oil cooler may be provided in the middle of the cooling oil passages 11rr and 11rl. These oil pumps OPrr and OPrl correspond to the "second electric oil pump" in the embodiment of the present invention.

[0035] exist Figure 3An example of a drive unit Pf on the front wheel 1r, 11 side is shown in a schematic diagram. The drive unit Pf has a bilaterally symmetrical structure, so it is described uniformly without special description as "right" or "left". The motors Mfr, Mfl are mounted in a manner such that their rotation center axes face the width direction (lateral direction) of the vehicle Ve, and drive gears 12fr, 12fl are mounted on their rotor shafts, and the drive gears 12fr, 12fl mesh with idle gears 13r, 13l. Subshafts 14r, 14l are provided parallel to the rotation center axes of the idle gears 13r, 13l, and the idle gears 13r, 13l mesh with counter driven gears 15fr, 15fl mounted on the subshafts 14r, 14l.

[0036] The counter driven gears 15fr and 15fl are made larger in diameter than the drive gears 12fr and 12fl mounted on the motors Mfr and Mrl, so that the gear pairs constitute a speed reduction mechanism. Counter drive gears 16fr and 16fl are mounted on the secondary shafts 14r and 14l, and the counter drive gears 16fr and 16fl mesh with driven gears 18fr and 18fl, which are gears integral with the drive shafts 17fr and 17fl connected to the front wheels 1r and 1l. The driven gears 18fr and 18fl are made larger in diameter than the counter drive gears 16fr and 16fl, so that the gear pairs constitute a speed reduction mechanism.

[0037] These front wheels 1r, 1l are equivalent to the "first drive wheel" in the embodiment of the present invention, these motors Mfr, Mfl are equivalent to the "first motor" in the embodiment of the present invention, and the part that transmits torque from these motors Mfr, Mfl to the front wheels 1r, 1l is equivalent to the "first drive unit" in the embodiment of the present invention.

[0038] The motors Mfr and Mfl on the front wheels 1r and 11 are similarly configured to be cooled by the oil 10f as the motors Mrr and Mrl on the rear wheels 2r and 21. That is, electric oil pumps OPfr and OPfl are provided corresponding to the motors Mfr and Mfl on the front wheels 1r and 11, and these oil pumps OPfr and OPfl are configured to draw the oil 10f from the oil reservoir 9f and supply the oil 10f to the motors Mfr and Mfl via the cooling oil passages 19fr and 19fl.

[0039] Although not particularly shown, the oil after cooling the motors Mfr and Mfl flows back to the oil reservoir 9r. In addition, an oil cooler may be provided in the middle of the cooling oil passages 19fr and 19fl. In addition, the oil pumps on the front wheels 1r and 11 may be provided as one oil pump that supplies oil 10f to the left and right motors Mfr and Mfl, similarly to the oil pumps on the rear wheels 2r and 21. These oil pumps OPfr and OPfl correspond to the "first electric oil pump" in the embodiment of the present invention.

[0040] An oil pump OPm is provided to draw oil for lubrication. The oil pump OPm is a mechanical pump. Figure 3 In the example shown, the oil pump OPm is connected to the countershaft 141 on the left front wheel 11 side. Therefore, the oil pump OPm is configured to be driven when the vehicle Ve is running, draws oil 10f from the oil reservoir 9f, and supplies the oil 10f to the gears, bearings, and other predetermined lubricating parts of the drive unit Pf provided on the front wheels 1r and 11 sides.

[0041] An electric storage device (Bat) 20 is provided for transferring electric power between the above-mentioned motors Mfr, Mfl, Mrr, Mrl, and oil pumps OPfr, OPfl, OPrr, OPrl. The electric storage device 20 is mainly composed of secondary batteries such as lithium-ion batteries and all-solid batteries. Each motor Mfr, Mfl, Mrr, Mrl is, for example, a permanent magnet synchronous motor, and these motors Mfr, Mfl, Mrr, Mrl are connected to the electric storage device 20 via power controllers PCfr, PCfl, PCrr, PCrl mainly composed of inverters. Therefore, each motor Mfr, Mfl, Mrr, Mrl independently controls its output torque and braking torque during energy regeneration. In addition, the functions of the power controllers PCfr, PCfl, PCrr, PCrl can be independent of each other, or they can be configured as an integrated unit as a whole.

[0042] The vehicle Ve configured as described above can control the output torque of each motor Mfr, Mfl, Mrr, and Mrl independently of each other, so that, for example, it is possible to switch between a two-wheel drive driving mode in which the motors Mrr and Mrl are controlled as a driving force source and the power supply to the motors Mfr and Mfl is stopped, and a four-wheel drive driving mode in which the motors Mfr, Mfl, Mrr, and Mrl are controlled as a driving force source. In addition, when driving in the four-wheel drive driving mode, the output torque ratio of the front and rear motors can be appropriately changed based on the driving characteristics required by the driver.

[0043] Such a mode selection switch (mode selection unit) 21 for the driver to select the driving characteristics (driving mode) is provided on the vehicle Ve. Specifically, the driving mode is a control method that controls the driving torque mainly based on a predetermined reference, and is a tracking mode that controls the driving torque and regenerative torque (braking torque) of each motor Mfr, Mfl, Mrr, and Mrl to improve the turning performance, a drift mode that controls the torque of each of the four wheels individually to eliminate understeering or controls to the optimal traction to improve the agility and driving accuracy during turning, and a manual sports mode that controls the gear (speed ratio) and ensures a large driving torque until a high vehicle speed to improve the acceleration performance or power performance. These driving modes control the balance of the torque of the front and rear wheels or output a large driving torque, and are equivalent to a four-wheel drive driving mode that drives all the motors Mfr, Mfl, Mrr, and Mrl to drive.

[0044] Furthermore, the driving mode is selected by the mode selection switch 21, or the selection is canceled to select the normal mode. In addition, a plurality of mode selection switches 21 may be provided corresponding to the driving modes, or a single mode selection switch may be provided to sequentially switch the driving mode selected according to the number of times the mode selection switch is operated.

[0045] in addition, Figure 1 The vehicle Ve shown is configured to be able to set a manual shift mode in which a driving characteristic is changed according to a shift operation by the driver, the driving characteristic being the relationship between the accelerator operation amount and the required driving torque. The manual shift mode is configured to be able to select four shift positions, for example, D, 3, 2, and L (or 1).

[0046] exist Figure 4 An example of a driving torque map for determining the required driving torque when the D range is selected is shown in FIG. Figure 4 The horizontal axis of the graph is the vehicle speed, the vertical axis is the required drive torque, and each accelerator opening is represented by a curve. That is, the larger the accelerator opening, the larger the required drive torque is set, and the higher the vehicle speed, the smaller the required drive torque is set. In this way, the drive torque map for determining the required drive torque based on the accelerator opening and the vehicle speed is determined for each selected shift position.

[0047] In addition, Figure 5 In order to show the difference in the required driving torque for each shift position, the required driving torque set when the accelerator opening is 50% is shown. Figure 5 The horizontal axis is the vehicle speed, and the vertical axis is the required driving torque. Figure 5Requested drive torques set when the D range, the 3rd range, the 2nd range, and the L range are selected are shown in order from the bottom. That is, the drive torque map corresponding to each shift range is determined so that the requested drive torque increases as the shift range changes from the D range to the L range.

[0048] The above-mentioned shift position switching can be configured by operating a shift lever set on the floor, center console, etc. to select the shift position, or it can be configured by operating a shift switch such as a paddle switch set on the instrument panel, steering wheel or steering column to select the shift position.

[0049] exist Figure 6 2 shows an example of the structure of the shift device 22 for selecting the shift position by operating the shift lever. Figure 6 The shift device 22 shown in the figure has the same structure as a conventional shift device used in a vehicle equipped with a conventional automatic transmission (multi-speed transmission), and is configured so that a shift lever 22b is moved in a certain direction. Figure 6 The shifting device 22 is configured to move the shifting rod 22b from the D position to the N position, thereby selecting the D position, the N position, the R position, and the P position. Figure 6 The shift guide groove 22c shown on the right side of the cam is moved to select the manual mode. Figure 6 The movement of the shift gate 22c shown on the right side of FIG. 1 is detected by the neutral position detection switch 23 provided on the shift gate 22c.

[0050] Furthermore, in the manual shift mode, by moving the shift lever 22b to the upshift (+) side in the shift guide 22c, the gear shift is shifted by one gear to a direction in which the required drive torque decreases. That is, the gear shifting is performed in a manner equivalent to upshifting in a conventional transmission. On the other hand, by moving the shift lever 22b to the downshift (-) side, the gear shift is shifted by one gear to a direction in which the required drive torque increases. That is, the gear shifting is performed in a manner equivalent to downshifting in a conventional transmission.

[0051] exist Figure 7 An example of the structure of the shift device 22 for selecting the shift position by operating the paddle switch is shown in FIG. Figure 7 In the example shown, a paddle switch 25 is provided on the steering wheel 24, similar to the conventional paddle switches used in vehicles equipped with conventional automatic transmissions (multi-speed transmissions). When the manual transmission mode is selected by the shift device 22 or the like, the paddle switch (upshift switch) 25a is operated once (set to be turned on), thereby shifting the gear by one gear in the direction in which the required driving torque decreases. That is, the gear position is switched to the upshift position in the conventional transmission. In addition, when the manual transmission mode is selected by the shift device 22 or the like, the paddle switch (upshift switch) 25a is operated once (set to be turned on). Figure 7The paddle switch (downshift switch) 25b shown is operated once (turned on), thereby shifting the gear by one gear to a direction in which the required drive torque increases. That is, the gear is switched to a gear position corresponding to downshifting in a conventional transmission.

[0052] The above-mentioned change of the shift position is similar to that of a vehicle equipped with a conventional automatic transmission. Based on a signal input from the shift device 22 to the controller 26 described later, the controller 26 determines whether or not to switch the shift position. Figure 8 The flowchart shown in FIG. 1 briefly explains an example of control for determining whether or not to switch the shift position. Figure 8 In the control example shown, first, it is determined whether the manual mode is selected by the shift device 22, that is, whether manual operation is performed (S1). If manual operation is performed, a switch signal generated by operating the shift lever 22b or the paddle switch 25 is received (S2).

[0053] Next, the required shift position based on the operation of the shift lever 22b and the paddle switch 25 is selected, and the drive torque map corresponding to the selected required shift position is called out (S3). Then, referring to the called out drive torque map, the required drive torque is calculated according to the current vehicle speed and accelerator opening, and it is determined whether the calculated required drive torque is greater than the torque obtained by summing the maximum torques of all motors Mfr, Mfl, Mrr, and Mrl, etc., and whether the required drive torque can be output at the current vehicle speed (S4). If the required drive torque can be output, the shift position is switched (S5), and if the required drive torque cannot be output, the shift position is rejected (S6). In addition, if no manual operation is performed, the routine is directly terminated.

[0054] Therefore, in the manual mode, when the gear position corresponding to the driver's gear shift operation can be switched, for example, when the D gear is changed to the L gear in a very short time, the required drive torque will increase sharply. In addition, the manual mode is usually selected when a relatively large drive torque is required, so after switching to the manual mode, the accelerator opening increases and the required drive torque may increase. Therefore, it is configured to drive all the motors Mfr, Mfl, Mrr, and Mrl to travel when the manual mode is selected. That is, the manual mode is equivalent to the four-wheel drive travel mode.

[0055] A controller 26 is provided for controlling the motors Mfr, Mfl, Mrr, Mrl, and the electric oil pumps OPrl, OPrr, OPfl, and OPfr based on the above-mentioned driving mode, shift position, etc. The controller 26 is mainly composed of a microcomputer, and is configured to use input data and pre-stored data to perform calculations according to a prescribed program, and output the results of the calculations as control command signals to the above-mentioned motors Mfr, Mfl, Mrr, Mrl, and the electric oil pumps OPrl, OPrr, OPfl, and OPfr.

[0056] Fig. 9 Examples of input signals and output signals for executing such control are listed. Examples of input signals are vehicle speed signals, accelerator opening signals, shift position signals, driving mode selection switch signals, upshift (+) signals, downshift (-) signals, neutral position detection switch signals, tracking mode signals, drift mode signals, etc. Examples of output command signals are torque of motor Mrl for left rear wheel 2l, torque of motor Mrr for right rear wheel 2r, control signal of oil pump OPrl for left rear wheel 2l, control signal of oil pump OPrr for right rear wheel 2r, torque of motor Mfl for left front wheel 1l, torque of motor Mfr for right front wheel 1r, control signal of oil pump OPfl for left front wheel 1l, control signal of oil pump OPfr for right front wheel 1r, etc.

[0057] When the vehicle Ve described above selects the two-wheel drive mode, the motors Mrr and Mrl are driven, and the power supply to the motors Mfr and Mfl is stopped. Therefore, in order to reduce the power consumption of the vehicle Ve, the oil pump OPrl for the left rear wheel 21 and the oil pump OPrr for the right rear wheel 2r are operated, and the oil pump OPfl for the left front wheel 11 and the oil pump OPfr for the right front wheel 1r are stopped. On the other hand, when the four-wheel drive mode is selected, the motors Mfr, Mfl, Mrr, and Mrl are driven. Therefore, in order to cool the motors Mfr, Mfl, Mrr, and Mrl, the electric oil pumps OPrl, OPrr, OPfl, and OPfr are operated. Therefore, the controller 26 is configured to start the oil pump OPfl for the left front wheel 11 and the oil pump OPfr for the right front wheel 1r when the switch to the four-wheel drive mode is predicted when the two-wheel drive mode is selected and the vehicle Ve is driven.

[0058] exist Fig.10 An example of a functional structure for controlling each of the electric oil pumps OPrl, OPrr, OPfl, and OPfr in the controller 26 is shown in FIG. Fig.10In the example shown, the pump selection unit 27, the prediction unit 28 and the start control unit 29 are configured. The pump selection unit 27 is configured to select the oil pump OPrl for the left rear wheel 21 and the oil pump OPrr for the right rear wheel 2r as the electric oil pumps for driving when the two-wheel drive driving mode is selected. In addition, the prediction unit 28 is configured to predict the situation of driving in the four-wheel drive driving mode based on the on / off signal of the mode selection switch 21, the switch signal of the shift device 22, etc. Moreover, the start control unit 29 is configured to start the stopped electric oil pumps (the oil pump OPfl for the left front wheel 11 and the oil pump OPfr for the right front wheel 1r) when the situation of driving in the four-wheel drive driving mode is predicted.

[0059] Reference Fig.11 The flowchart shown in FIG. 1 is a flowchart illustrating an example of control by the controller 26. Fig.11 In the control example shown, first, input data is obtained in S1. The input data obtained here are accelerator opening, vehicle speed, motor temperature, oil temperature, gear shift position, driving mode, etc. Next, it is determined whether the four-wheel drive driving mode is selected or set. Specifically, it is determined whether the aforementioned tracking mode (S2) is selected or set, or the drift mode (S3) is selected or set, or the manual sports mode (S4) is selected or set. S2 to S4 can be determined based on the signal input from the mode selection switch 21 to the controller 26. In addition, the order of these judgments is not particularly limited and can be changed appropriately.

[0060] In addition, as described above, in the manual mode, four-wheel drive is preferably performed. Therefore, in addition to the above-mentioned S2 to S4, it may be determined whether the manual mode is selected or set.

[0061] The above-mentioned tracking mode, drift mode or manual sports mode is a driving mode selected in a special environment such as driving on a circular track. Therefore, under normal circumstances, the above-mentioned driving modes are not selected, so the results of the judgments from S2 to S4 are "No". In this case, the two-wheel drive driving mode as the normal mode is required, or the two-wheel drive driving mode is set to drive, so only the oil pumps OPrr and OPrl corresponding to the rear wheels 2r and 21 as the driving wheels are driven to actively supply oil to the motors Mrr and Mrl for the rear wheels 2r and 21 to promote their cooling (S5). That is, the oil pumps OPfr and OPfl corresponding to the front wheels 1r and 11 are stopped or maintained in a stopped state. In this state, drive control using the drive torque of the left and right rear wheels 2r and 21 is performed (S6). Then return.

[0062] Here, “using the driving torque of the left and right rear wheels 2r, 21” means controlling the driving torque of each of the rear wheels 2r, 21 by using the motors Mrr, Mrl provided corresponding to the rear wheels 2r, 21, respectively.

[0063] When the two-wheel drive driving mode is set, since the motors Mfr and Mfl are not energized, the motors Mfr and Mfl will not generate heat and are not required to be cooled. Therefore, by stopping or maintaining the oil pumps OPfr and OPfl corresponding to the front wheels 1r and 1l, the power consumption of the vehicle Ve as a whole can be reduced. That is, the reduction in the cooling performance of the motors Mrr and Mrl that serve as the driving force source in the two-wheel drive driving mode can be suppressed, and the energy efficiency can be improved. In other words, by providing an electric oil pump that only supplies oil to the motors Mfr and Mfl that are stopped when driving in the two-wheel drive driving mode, the oil pumps OPrr and OPrl corresponding to the rear wheels 2r and 2l can be used as long as they have the function of cooling the motors Mrr and Mrl, so the oil pumps OPrr and OPrl can be miniaturized.

[0064] In addition, when the vehicle is traveling in the two-wheel drive driving mode, the front wheels 1r and 11 rotate, and each rotating member constituting the drive unit Pf also rotates at a rotation speed corresponding to the vehicle speed. That is, the mechanical oil pump OPm is operated. Therefore, since oil is supplied to the lubricating parts of the drive unit Pf, the durability of the drive unit Pf can be suppressed from being reduced. In other words, since oil is supplied only to the parts to which oil should be supplied, the power loss for driving the oil pump can be reduced.

[0065] On the other hand, if the result of any of the judgments in S2 to S4 is "yes", the vehicle is traveling in the four-wheel drive mode, or a switch from the two-wheel drive mode to the four-wheel drive mode is required, and therefore, the oil pumps OPfr, OPfl, OPrr, OPrl provided corresponding to the front and rear four wheels are driven to actively supply oil to the motors Mfr, Mfl, Mrr, Mrl to promote their cooling (S7). In this state, the drive control using the drive torque of the front and rear four wheels is executed (S8). Then the return is returned.

[0066] Here, "drive control using the drive torque of the front and rear four wheels" means that the drive torque of each wheel 1r, 1l, 2r, 2l is individually controlled by individually controlling the motors Mfr, Mfl, Mrr, Mrl respectively provided corresponding to the front and rear wheels 1r, 1l, 2r, 2l, thereby driving the vehicle Ve to control driving, and appropriately controlling the distribution ratio of the torque of the front and rear wheels, the distribution ratio of the torque of the left and right wheels, etc. according to various factors such as the required driving torque, the slope angle of the driving road or the turning radius.

[0067] The above-mentioned tracking mode, drift mode or manual sports mode is usually set in special conditions such as driving on a circular track. The mode selection switch 21 is operated when the vehicle is stopped in the normal mode, and then the accelerator operation corresponding to the selected driving mode is performed to drive the vehicle. That is, it is required to drive the motors Mfr and Mfl after switching the driving mode. Therefore, in the above-mentioned control example, the operation of the driving mode selection switch 21 is used as a means to predict the situation of driving in the four-wheel drive driving mode.

[0068] Furthermore, when the mode selection switch 21 is operated as described above and it is predicted that the vehicle will travel in any of the following driving modes, the drifting mode, and the manual sport mode, the stopped oil pumps OPfr and OPfl are started to operate, so that oil can be supplied to the motors Mfr and Mfl for cooling before the motors Mfr and Mfl are energized and heated. As a result, when the vehicle travels in the four-wheel drive driving mode, the oil pumps OPfr and OPfl can be operated in advance, so that the cooling performance of the motors Mfr and Mfl can be suppressed from being reduced.

[0069] When the oil pumps OPfr, OPfl, OPrr, and OPrl are operated as described above, the rotation speeds of the oil pumps OPfr, OPfl, OPrr, and OPrl, that is, the oil supply amounts to the motors Mfr, Mfl, Mrr, and Mrl, are preferably determined according to the temperatures of the motors Mfr, Mfl, Mrr, and Mrl. Specifically, it is preferred that the rotation speed of the oil pump OPfr is set higher as the temperature of the motor Mfr is higher, the rotation speed of the oil pump OPfl is set higher as the temperature of the motor Mfl is higher, the rotation speed of the oil pump OPrr is set higher as the temperature of the motor Mrr is higher, and the rotation speed of the oil pump OPrl is set higher as the temperature of the motor Mrl is higher.

[0070] By controlling the rotation speeds of the oil pumps OPfr, OPfl, OPrr, OPrl according to the temperatures of the motors Mfr, Mfl, Mrr, Mrl in this way, the motors Mfr, Mfl, Mrr, Mrl can be appropriately cooled and power consumption can be reduced.

[0071] In addition, the above-mentioned tracking mode, drift mode, manual sports mode and manual gear mode have a tendency to require a driving torque that becomes larger in sequence. Therefore, it is preferred to set the speeds of the oil pumps OPfr, OPfl, OPrr, and OPrl in the order of tracking mode, drift mode, manual sports mode and manual gear mode from low to high. That is, it is preferred to use the selected driving mode and motor temperature as parameters to determine the speeds of the oil pumps OPfr, OPfl, OPrr, and OPrl. Fig.12The map shown is stored in the controller 26, and when the vehicle is traveling in the four-wheel drive traveling mode, the controller 26 operates the oil pumps OPfr, OPfl, OPrr, and OPrl with reference to the map.

[0072] By controlling the rotation speeds of the oil pumps OPfr, OPfl, OPrr, OPrl in accordance with the selected running mode, the motors Mfr, Mfl, Mrr, Mrl can be appropriately cooled, and the power consumption can be reduced.

[0073] In addition, in the electric vehicle in the embodiment of the present invention, the rear wheels 2r and 21 are used as driving wheels in the two-wheel drive driving mode, but the front wheels 1r and 11 can also be used as driving wheels. In this case, a mechanical oil pump is set in the drive unit Pr, and the oil pumps OPrr and OPrl can be stopped in the two-wheel drive driving mode.

[0074] In addition, the vehicle Ve may include a mechanical oil pump in the drive unit Pf and the drive unit Pr. In this case, the drive wheels when traveling in the two-wheel drive travel mode may be appropriately switched between the front wheels 1r, 11 and the rear wheels 2r, 21 according to the travel environment, etc. When the drive wheels in the two-wheel drive travel mode are switched in this way, the oil pumps OPrr, OPrl (OPfr, OPfl) provided in the drive unit Pr (Pf) different from the drive unit Pf (Pr) connected to the drive wheels may be stopped.

[0075] Moreover, in Figure 2 In the example shown, an oil pump for supplying oil to the lubricating parts of the drive unit Pr is not shown, but the drive unit Pr may be configured to be lubricated appropriately by providing a mechanical oil pump or the like. In addition, the rear wheels 2r and 21 of the vehicle Ve described above function as drive wheels regardless of whether they are in the two-wheel drive driving mode or the four-wheel drive driving mode, so the oil pumps OPrr and OPrl may be configured to supply oil to the lubricating parts of the drive unit Pr.

[0076] In addition, in the above control example, the situation of traveling in the four-wheel drive driving mode is predicted based on the signal input from the mode selection switch 21 to the controller 26. However, for example, when the rate of change of the accelerator opening during traveling in the two-wheel drive driving mode changes at a predetermined rate of change, or when it is predicted that the required driving torque will increase to a driving torque that cannot be satisfied by the torque of the motors Mrr and Mrl alone, it is predicted that traveling in the four-wheel drive driving mode is performed. That is, the situation of traveling in the four-wheel drive driving mode can also be predicted based on a signal other than the mode selection switch 21.

Claims

1. A cooling control device for an electric vehicle, the electric vehicle comprising: a first motor, the first motor driving a first drive wheel, the first drive wheel being one of the front wheels and the rear wheels; a first electric oil pump, the first electric oil pump supplying oil to the first motor; a second motor, the second motor driving a second drive wheel, the second drive wheel being the other of the front wheels and the rear wheels; a second electric oil pump that supplies the oil to the second motor; a first drive unit that transmits torque from the first motor to the first drive wheel; and a second drive unit that transmits torque from the second motor to the second drive wheel; and a mechanical oil pump, the mechanical oil pump being operated by the first drive unit to supply the oil to the first drive unit, the electric vehicle being capable of switching between a four-wheel drive driving mode using the first motor and the second motor as driving power sources and a two-wheel drive driving mode using the second motor as driving power source, wherein: The cooling control device of the electric vehicle includes a controller that controls the first electric oil pump and the second electric oil pump. The controller has: a pump selection unit configured to drive only the second electric oil pump of the first electric oil pump and the second electric oil pump when the two-wheel drive travel mode is selected; a prediction unit that predicts a situation in which the vehicle is traveling in the four-wheel drive traveling mode; and A start control unit is configured to start operating the first electric oil pump when the prediction unit predicts that the vehicle will travel in the four-wheel drive travel mode.

2. The cooling control device for an electric vehicle according to claim 1, wherein: The cooling control device for an electric vehicle includes a mode selection unit operated by a driver to select the four-wheel drive travel mode. The prediction unit predicts that the vehicle will travel in the four-wheel drive travel mode based on whether or not the mode selection unit is operated.

3. The cooling control device for an electric vehicle according to claim 1, wherein: The higher the temperature of the first motor, the more the controller increases the supply amount of the oil based on the first electric oil pump relative to the oil of the first motor, and the higher the temperature of the second motor, the more the controller increases the supply amount of the oil based on the second electric oil pump relative to the oil of the second motor.

4. The cooling control device for an electric vehicle according to claim 1, wherein: The four-wheel drive driving mode includes a plurality of driving modes. The controller controls an amount of the oil supplied to the first motor by the first electric oil pump and an amount of the oil supplied to the second motor by the second electric oil pump according to the plurality of travel modes.

5. The cooling control device for an electric vehicle according to any one of claims 1 to 4, wherein: The four-wheel drive driving mode includes at least any one of a tracking mode, a drift mode, a sports mode and a manual gear mode. The tracking mode is a mode that improves cornering performance compared to the two-wheel drive driving mode. The drift mode is a mode that improves driving accuracy. The sports mode is a mode that improves acceleration performance or power performance. The manual gear mode is a mode that controls the driving torque of the first motor and the second motor based on driving characteristics corresponding to the driver's gear shifting operation.

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