Cooling control device of electric vehicle

Abstract

To provide a control device of a four-wheel driving vehicle which can improve energy efficiency, while suppressing lowering of cooling performance of driving force sources.SOLUTION: There is provided a cooling control device of an electric vehicle, which includes 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 can perform switching between a four-wheel drive traveling mode and a two-wheel drive traveling mode using the second motor as a driving force source, the cooling control device driving only the second electric oil pump when the two-wheel drive traveling mode is selected (step S5), and starting to operate the first electric oil pump when it is predicted that the vehicle travels in the four-wheel drive traveling mode (step S7).SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to a control device for cooling a 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 the motor by oil. [Background technology]

[0002] Patent Document 1 describes a control device for a four-wheel drive vehicle that includes a front motor as a drive power source for a pair of front wheels, and a rear motor as a drive power source for a pair of rear wheels and that has a lower thermal rating or lower cooling performance than the front motor. This control device is configured to maintain the drive power required by the vehicle by increasing the output of the front motor when operation of the rear motor is restricted, and to ensure driving stability by setting the torque distribution ratio between the front and rear wheels to a desired distribution ratio by reducing the output of the rear motor when operation of the front motor is restricted.

[0003] Patent Document 2 describes a hybrid vehicle that has an engine and a motor as driving power sources and can set an HV driving mode in which the engine is driven to drive the vehicle and an EV driving mode in which the engine is stopped and the motor is driven to drive the vehicle. This hybrid vehicle also has a mechanical oil pump driven by the engine power and an electric oil pump driven by an electric motor in parallel, and is configured so that when the viscosity of the refrigerant discharged by these oil pumps is high, only one of the mechanical oil pump and the electric oil pump, which has a higher discharge power, is driven, and when the viscosity of the refrigerant is low, only the other oil pump is driven. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-112114 A [Patent Document 2] JP 2014-000848 A Summary of the Invention [Problem to be solved by the invention]

[0005] The four-wheel drive vehicle described in Patent Document 1 can drive a pair of front wheels and a pair of rear wheels independently, so that it is possible to run in two-wheel drive mode by driving only one of the driving power sources. In addition, since the vehicle is equipped with multiple driving power sources, it is considered that multiple oil pumps for cooling or one large oil pump will be provided in order to ensure the cooling performance of the driving power sources during four-wheel drive. In the case where multiple oil pumps or a large oil pump are provided in this way, driving each oil pump during two-wheel drive mode results in a loss of power or motive power for driving the oil pumps, which may reduce the energy efficiency of the vehicle as a whole.

[0006] The present invention has been made in light of the above-mentioned technical problems, and aims to provide a control device for a four-wheel drive vehicle that can improve energy efficiency while suppressing a decrease in the cooling performance of the driving force source. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides a vehicle driving system including a first motor that drives a first drive wheel which is one of the front wheels and the rear wheels, a first electric oil pump that supplies oil to the first motor, a second motor that drives a second drive wheel which is 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, a second drive unit that transmits torque from the second motor to the second drive wheel, and a mechanical oil pump that is operated by the first drive unit to supply the oil to the first drive unit, and and a two-wheel drive driving mode in which the second motor is used as a driving force source, the cooling control device for an electric vehicle being capable of switching between a first electric oil pump and a second electric oil pump, the cooling control device including a controller for controlling the first electric oil pump and the second electric oil pump, the controller including a pump selection unit for driving only the second electric oil pump out of the first electric oil pump and the second electric oil pump when the two-wheel drive driving mode is selected, a prediction unit for predicting that driving will be in the four-wheel drive driving mode, and a start control unit for starting operation of the first electric oil pump when the prediction unit predicts that driving will be in the four-wheel drive driving mode.

[0008] In the present invention, a mode selection unit is provided that is operated by the driver to select the four-wheel drive driving mode, and the prediction unit may predict that driving will be in the four-wheel drive driving mode based on whether or not the mode selection unit is operated.

[0009] In the present invention, the controller may increase the amount of oil supplied by the first electric oil pump to the first motor as the temperature of the first motor increases, and may increase the amount of oil supplied by the second electric oil pump to the second motor as the temperature of the second motor increases.

[0010] In the present invention, the four-wheel drive driving mode may include a plurality of driving modes, and the controller may control the amount of oil supplied by the first electric oil pump to the first motor and the amount of oil supplied by the second electric oil pump to the second motor in accordance with the plurality of driving modes.

[0011] In the present invention, the four-wheel drive driving mode may include at least one of a track mode which provides improved cornering performance compared to the two-wheel drive driving mode, a drift mode which improves driving precision, a sport mode which provides improved acceleration performance or power performance, and a manual range mode which controls the driving torque of the first motor and the second motor based on driving characteristics corresponding to the driver's shift operation. Effect of the Invention

[0012] According to the present invention, the vehicle includes a first motor for driving a first drive wheel, which is one of the front and rear wheels, and a second motor for driving a second drive wheel, which is the other wheel, and when the 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 the first electric oil pump provided corresponding to the first motor in a stopped state, the power consumption of the entire electric vehicle can be reduced. That is, it is possible to improve energy efficiency while suppressing a decrease in the cooling performance of the second motor, which is the driving force source in the two-wheel drive driving mode. In other words, by providing a first electric oil pump that supplies oil only to the first motor that is stopped when traveling in the two-wheel drive driving mode, the second electric oil pump provided corresponding to the second motor only needs to have a function of cooling the second motor, so that the second electric oil pump can be made smaller.

[0013] Also, when traveling in two-wheel drive mode, the first drive wheel rotates, causing the first drive unit to rotate at a rotation speed according to the vehicle speed. That is, the mechanical oil pump operates. Therefore, oil is supplied to the lubricated parts of the first drive unit, so that the durability of the first drive unit can be prevented from decreasing. In other words, oil is supplied only to the parts to which oil should be supplied, so that the power loss for driving the mechanical oil pump can be reduced.

[0014] Furthermore, when it is predicted that the vehicle will travel in four-wheel drive mode, the first electric oil pump, which has been stopped, is started to operate, so that oil can be supplied to and cooled by the first motor before it is energized to generate electricity. As a result, the first electric oil pump can be kept operating when the vehicle travels in four-wheel drive mode, thereby preventing a decrease in the cooling performance of the first motor. [Brief description of the drawings]

[0015] [Figure 1] 1 is a block diagram showing a schematic diagram of a drive system of a four-wheel independent drive vehicle according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a skeleton diagram showing an example of a rear wheel side drive unit. [Diagram 3] FIG. 2 is a skeleton diagram showing an example of a front wheel side drive unit. [Figure 4] FIG. 4 is a diagram illustrating a required driving torque map used in a D range. [Diagram 5] FIG. 10 is a diagram that illustrates a required drive torque map when the accelerator opening is 50% in the D range or L range. [Figure 6] 1 is a diagram showing an example of a shift device for selecting a shift range by operating a shift lever; [Figure 7] 1 is a diagram showing an example of a shift device in which a shift range is selected by operating a paddle switch; [Figure 8] 5 is a flowchart illustrating an example of a control for determining whether or not to switch the shift range. [Figure 9] FIG. 4 is a block diagram illustrating input and output signals of a controller. [Figure 10] FIG. 2 is a block diagram showing a functional configuration of a controller. [Figure 11] 4 is a flowchart illustrating an example of control executed in the embodiment of the present invention. [Figure 12] 4 is a diagram showing an example of a map in which the rotation speed of the oil pump for each driving mode is determined. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Next, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the embodiment described below is merely an example of the case where the present invention is implemented, and is not intended to limit the present invention.

[0017] The electric vehicle targeted by the present invention is an electric vehicle having a total of four wheels, two front wheels and two rear wheels, in which the two front wheels and the two rear wheels are each provided with a motor as a driving force source, and the two front wheels and the two rear wheels can be driven independently of each other. The two front wheels may be connected to a driving force source for the front wheels via an appropriate differential mechanism, and the two rear wheels may be connected to a driving force source for the rear wheels via another appropriate differential mechanism. Furthermore, the electric vehicle targeted by the present invention may be an electric vehicle configured to provide a motor as a driving force source corresponding to each of the front and rear four wheels, so that the driving torque and regenerative braking torque (regenerative torque) of each of the four wheels can be controlled independently of each other.

[0018] Fig. 1 shows a schematic example of a four-wheel independent drive vehicle that is configured so that all four wheels can be driven independently in addition to being able to control the drive torque or regenerative braking torque of the front and rear wheels independently. The electric vehicle (hereinafter simply referred to as the vehicle) Ve shown here has left and right front wheels 1r, 1l and left and right rear wheels 2r, 2l, and is provided with drive units Pf, Pr as drive force sources corresponding to the front wheels 1r, 1l and the rear wheels 2r, 2l, respectively. Each of these drive units Pf, Pr is mainly composed of a motor and a gear reduction mechanism (transmission mechanism).

[0019] An example of a drive unit Pr on the side of the rear wheels 2r, 2l is shown in a skeleton diagram in Fig. 2. This drive unit Pr is composed of a pair of drive systems that independently control the left and right rear wheels 2r, 2l, and since these drive systems are symmetrical, they will be described together without being specifically designated as "right" and "left". In the following description, when the suffix of a reference symbol is one letter, "f" indicates the front wheel, "l" indicates the left wheel, and "r" indicates the right wheel or the rear wheel, and when it is two letters, the first letter "f" indicates the front wheel, "r" indicates the rear wheel, and the second letter "r" indicates the right wheel, and "l" indicates the left wheel.

[0020] The drive unit Pr of the rear wheels 2r, 2l is equipped with motors Mrr, Mrl with their central axis of rotation directed in the longitudinal direction of the vehicle Ve, and drive gears 3rr, 3rl are attached to the rotor shafts thereof, and the drive gears 3rr, 3rl are meshed with the counter driven gears 4rr, 4rl. The counter driven gears 4rr, 4rl have a larger diameter than the drive gears 3rr, 3rl, and therefore these gear pairs constitute a reduction mechanism. The counter driven gears 4rr, 4rl 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 are meshed with the driven gears 7rr, 7rl which are bevel gears integral with the drive shafts 6rr, 6rl connected to the rear wheels 2r, 2l. By making the driven gears 7rr, 7rl larger in diameter than the counter drive gears 5rr, 5rl, these gear pairs can be used as a reduction mechanism.

[0021] These rear wheels 2r, 2l correspond to the "second drive wheels" in an embodiment of the present invention, these motors Mrr, Mrl correspond to the "second motor" in an embodiment of the present invention, and the parts that transmit torque from these motors Mrr, Mrl to the rear wheels 2r, 2l correspond to the "second drive unit" in an embodiment of the present invention.

[0022] These motors Mrr, Mrl, the reduction mechanism, and each bevel gear are housed in a liquid-tight state inside the casing 8. Electric oil pumps OPrr, OPrl are provided to supply oil for cooling and lubrication to the motors Mrr, Mrl inside the casing 8. The oil pump on the rear wheel 2r, 2l side may be a single oil pump that supplies oil 10r to the left and right motors Mrr, Mrl collectively. These oil pumps OPrr, OPrl are provided outside the casing 8 at appropriate locations on the vehicle Ve, and are configured to pump up oil 10r from an oil reservoir 9r and supply the oil 10r to the motors Mrr, Mrl via cooling oil passages 11rr, 11rl provided through the casing 8.

[0023] Although not shown, the oil 10r is configured to flow back to the oil reservoir 9r from inside the casing 8. An oil cooler may be provided in the oil cooling passages 11rr and 11rl. These oil pumps OPrr and OPrl correspond to the "second electric oil pump" in the embodiment of the present invention.

[0024] FIG. 3 shows a skeleton diagram of an example of the drive unit Pf on the front wheels 1r, 1l side. Since the drive unit Pf has a bilaterally symmetrical configuration, it will be described together without specifying "right" or "left". The motors Mfr, Mfl are mounted with their rotational center axis facing the width direction (lateral direction) of the vehicle Ve, and drive gears 12fr, 12fl are attached to the rotor shafts, and the drive gears 12fr, 12fl mesh with the idle gears 13r, 13l. Countershafts 14r, 14l are provided parallel to the rotational center axis of the idle gears 13r, 13l, and the idle gears 13r, 13l mesh with counter driven gears 15fr, 15fl attached to the countershafts 14r, 14l.

[0025] The counter driven gears 15fr, 15fl have a larger diameter than the drive gears 12fr, 12fl attached to the motors Mfr, Mrl, and these gear pairs form a reduction mechanism. The counter drive gears 16fr, 16fl are attached to the counter shafts 14r, 14l, and these counter drive gears 16fr, 16fl mesh with the driven gears 18fr, 18fl that are integral with the drive shafts 17fr, 17fl that are connected to the front wheels 1r, 1l. The driven gears 18fr, 18fl have a larger diameter than the counter drive gears 16fr, 16fl, and these gear pairs form a reduction mechanism.

[0026] These front wheels 1r, 1l correspond to the "first driving wheels" in an embodiment of the present invention, these motors Mfr, Mfl correspond to the "first motor" in an embodiment of the present invention, and the parts that transmit torque from these motors Mfr, Mfl to the front wheels 1r, 1l correspond to the "first driving unit" in an embodiment of the present invention.

[0027] The motors Mfr, Mfl on the front wheels 1r, 1l are configured to be cooled by oil 10f, similar to the motors Mrr, Mrl on the rear wheels 2r, 2l. That is, electric oil pumps OPfr, OPfl are provided corresponding to the motors Mfr, Mfl on the front wheels 1r, 1l, and these oil pumps OPfr, OPfl are configured to pump up oil 10f from an oil reservoir 9f and supply the oil 10f to the motors Mfr, Mfl via cooling oil passages 19fr, 19fl.

[0028] Although not shown, the oil that has cooled the motors Mfr, Mfl is configured to flow back to the oil reservoir 9r. An oil cooler may be provided in the cooling oil passages 19fr, 19fl. The oil pump on the front wheels 1r, 1l side may be a single oil pump that supplies oil 10f to the left and right motors Mfr, Mfl collectively, similar to the oil pump on the rear wheels 2r, 2l side described above. These oil pumps OPfr, OPfl correspond to the "first electric oil pump" in the embodiment of the present invention.

[0029] An oil pump OPm is provided to pump up oil for lubrication. This oil pump OPm is a mechanical pump, and in the example shown in Fig. 3, it is connected to the countershaft 14l on the left front wheel 1l side. Therefore, this oil pump OPm is driven when the vehicle Ve is running, and is configured to pump up oil 10f from the oil reservoir 9f and supply the oil 10f to predetermined lubrication points such as gears and bearings provided in the drive unit Pf on the front wheels 1r, 1l side.

[0030] An electric storage device (Bat) 20 is provided to exchange electric power between the motors Mfr, Mfl, Mrr, and Mrl and the oil pumps OPfr, OPfl, OPrr, and OPrl. The electric storage device 20 is mainly composed of secondary batteries such as lithium ion batteries and solid-state batteries. The motors Mfr, Mfl, Mrr, and Mrl are, for example, permanent magnet synchronous motors, and are connected to the electric storage device 20 via power controllers PCfr, PCfl, PCrr, and PCrl mainly composed of inverters. Therefore, the output torque and braking torque during energy regeneration of the motors Mfr, Mfl, Mrr, and Mrl are individually controlled independently of each other. Note that the power controllers PCfr, PCfl, PCrr, and PCrl only need to be independent of each other in function, and may be configured as an integrated unit as a whole.

[0031] The vehicle Ve configured as described above can control the output torque of each of the motors Mfr, Mfl, Mrr, Mrl independently of each other, and can therefore switch between, for example, a two-wheel drive mode in which the motors Mrr, Mrl are controlled as driving force sources and the power supply to the motors Mfr, Mfl is stopped, and a four-wheel drive mode in which the motors Mfr, Mfl, Mrr, Mrl are controlled as driving force sources. When traveling in the four-wheel drive mode, the output torque ratio between the front and rear motors can be appropriately changed based on the driving characteristics required by the driver.

[0032] A mode selection switch (mode selection unit) 21 for such a driver to select a driving characteristic (driving mode) is provided in the vehicle Ve. Specifically, the driving mode is a control form that mainly controls the driving torque based on a predetermined standard, and includes a track mode that controls the driving torque and regenerative torque (braking torque) of each motor Mfr, Mfl, Mrr, Mrl to improve cornering performance, a drift mode that individually controls the torque of each of the four wheels to eliminate understeer or to control to optimal traction to improve agility and driving accuracy during cornering, and a manual sports mode that controls the gear stage (gear ratio) to ensure a large driving torque up to a high vehicle speed to improve 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 therefore correspond to a four-wheel drive driving mode in which all motors Mfr, Mfl, Mrr, Mrl are driven to run.

[0033] The mode selection switch 21 is configured to select one of these driving modes, or to cancel the selection and select the normal mode. Note that a plurality of mode selection switches 21 may be provided corresponding to the driving modes, or a single mode selection switch may be provided and the selected driving mode may be switched in sequence depending on the number of times the switch is operated.

[0034] 1 is configured to be able to set a manual range mode in which the driving characteristics, which are the relationship between the accelerator operation amount and the required driving torque, are changed in response to the shift operation by the driver. This manual range mode is configured to be able to select four shift ranges, for example, D range, 3 range, 2 range, and L range (or 1 range).

[0035] Fig. 4 shows an example of a drive torque map for determining the required drive torque when the D range is selected. In Fig. 4, the horizontal axis represents vehicle speed, the vertical axis represents required drive torque, and each accelerator opening is shown 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, a drive torque map for determining the required drive torque according to the accelerator opening and vehicle speed is set for each selected shift range.

[0036] In addition, in order to show the difference in the required drive torque for each shift range, Fig. 5 shows the required drive torque set when the accelerator opening is 50%. Note that the horizontal axis in Fig. 5 represents vehicle speed and the vertical axis represents the required drive torque, and the curves indicate the required drive torque set when the D range, 3 range, 2 range, and L range are selected, in that order from the bottom in Fig. 5. In other words, a drive torque map corresponding to each shift range is determined so that the required drive torque increases as the shift range changes from the D range to the L range.

[0037] The above-mentioned shift range switching may be configured so that the shift range is selected by operating a shift lever provided on the floor or center console, or may be configured so that the shift range is selected by operating a shift switch such as a paddle switch provided on the instrument panel, steering wheel, steering column, etc.

[0038] FIG. 6 shows an example of the configuration of a shift device 22 that selects a shift range by operating a shift lever. The shift device 22 shown in FIG. 6 has the same configuration as an existing shift device used in a vehicle equipped with a conventional automatic transmission (multiple-speed transmission), and is configured to select a D position, an N position, an R position, and a P position by moving a shift lever 22b at a shift gate 22a shown on the left side of FIG. 6. The shift device 22 is also configured to select a manual range mode by moving the shift lever 22b from the D position to a shift gate 22c shown on the right side of FIG. 6. The movement of the shift lever 22b to the shift gate 22c shown on the right side of FIG. 6 is detected by a neutral position detection switch 23 provided on the shift gate 22c.

[0039] In the manual range mode, the shift gate 22c is used to move the shift lever 22b to the up (+) side to shift one step to a range in which the required drive torque decreases. That is, the range is changed over to correspond to an upshift in a conventional transmission. On the other hand, the shift lever 22b is used to move to the down (-) side to shift one step to a range in which the required drive torque increases. That is, the range is changed over to correspond to a downshift in a conventional transmission.

[0040] FIG. 7 shows an example of the configuration of the shift device 22 that selects the shift range by operating a paddle switch. In the example shown in FIG. 7, a paddle switch 25 is provided on the steering wheel 24, similar to an existing paddle switch used in a vehicle equipped with a conventional automatic transmission (multiple-speed transmission). When the manual range mode is selected by the shift device 22 or the like, the paddle switch (UP switch) 25a is operated once (turned ON) to shift one step to a range in the direction in which the required driving torque becomes smaller. That is, the range is switched corresponding to an upshift in a conventional transmission. Also, when the manual range mode is selected by the shift device 22 or the like, the paddle switch (DOWN switch) 25b shown in FIG. 7 is operated once (turned ON) to shift one step to a range in the direction in which the required driving torque becomes larger. That is, the range is switched corresponding to a downshift in a conventional transmission.

[0041] The above-mentioned change of the shift range is configured so that the controller 26 determines whether or not to switch the shift range based on a signal input from the shift device 22 to the controller 26, which will be described later, in the same manner as in a vehicle equipped with a conventional automatic transmission. An example of the control for determining whether or not to switch the shift range will be briefly described with reference to the flowchart shown in Fig. 8. In the control example shown in Fig. 8, first, it is determined whether or not the manual range mode has been selected by the shift device 22, that is, whether or not manual operation has been performed (step S1), and if manual operation has been performed, a switch signal resulting from operation of the shift lever 22b or the paddle switch 25 is accepted (step S2).

[0042] Next, the shift lever 22b or the paddle switch 25 is operated to select a required shift range, and a drive torque map corresponding to the selected required shift range is called up (step S3). The called-up drive torque map is then used to calculate a required drive torque from the current vehicle speed and accelerator opening, and the required drive torque is determined whether it is possible to output the required drive torque at the current vehicle speed (step S4), for example, by determining whether the calculated required drive torque is equal to or greater than the total maximum torque of all motors Mfr, Mfl, Mrr, and Mrl. If the required drive torque can be output, the shift range is switched (step S5), and if the required drive torque cannot be output, the shift range switching is rejected (step S6). If the shift range is not manually operated, the routine is terminated.

[0043] Therefore, in the manual range mode, when the shift range can be switched in response to the driver's shift operation, for example, when the D range is changed to the L range in a very short time, the required drive torque increases rapidly. Also, since the manual range mode is usually selected when a relatively large drive torque is required, there is a possibility that the accelerator opening increases and the required drive torque increases after switching to the manual range mode. Therefore, when the manual range mode is selected, the vehicle is configured to drive all of the motors Mfr, Mfl, Mrr, and Mrl to run. In other words, the manual range mode corresponds to a four-wheel drive running mode.

[0044] A controller 26 is provided for controlling the motors Mfr, Mfl, Mrr, Mrl and the electric oil pumps OPrl, OPrr, OPfl, OPfr based on the above-mentioned driving mode, shift range, etc. The controller 26 is mainly constituted by a microcomputer, and is configured to perform calculations according to a predetermined program using input data and pre-stored data, and to 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, OPfr.

[0045] Examples of input signals and output signals for performing such control are shown in Fig. 9. Examples of input signals are a vehicle speed signal, an accelerator opening signal, a shift position signal, a driving mode selection switch signal, a shift up (+) signal, a shift down (-) signal, a neutral position detection switch signal, a track mode signal, a drift mode signal, etc. Examples of output command signals are the torque of the motor Mrl for the left rear wheel 2l, the torque of the motor Mrr for the right rear wheel 2r, a control signal for the oil pump OPrl for the left rear wheel 2l, a control signal for the oil pump OPrr for the right rear wheel 2r, the torque of the motor Mfl for the left front wheel 1l, the torque of the motor Mfr for the right front wheel 1r, a control signal for the oil pump OPfl for the left front wheel 1l, and a control signal for the oil pump OPfr for the right front wheel 1r.

[0046] In the above-mentioned vehicle Ve, when the two-wheel drive mode is selected, 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 2l and the oil pump OPrr for the right rear wheel 2r are operated, and the oil pump OPfl for the left front wheel 1l 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, Mrl, and Mrl are driven. Therefore, in order to cool the motors Mfr, Mfl, Mrl, and Mrl, the electric oil pumps OPrl, OPrr, OPfl, and OPfr are operated. Therefore, when the two-wheel drive mode is selected and the vehicle is traveling, the controller 26 is configured to start operating the oil pump OPfl for the left front wheel 1l and the oil pump OPfr for the right front wheel 1r when a switch to the four-wheel drive mode is predicted.

[0047] FIG. 10 shows an example of a functional configuration for controlling the electric oil pumps OPrl, OPrr, OPfl, and OPfr in the controller 26. In the example shown in FIG. 10, the controller 26 is configured to include a pump selection unit 27, a prediction unit 28, and a start control unit 29. The pump selection unit 27 is configured to select the oil pump OPrl for the left rear wheel 2l and the oil pump OPrr for the right rear wheel 2r as the electric oil pump to be driven when the two-wheel drive driving mode is selected. The prediction unit 28 is configured to predict that the vehicle will travel in the four-wheel drive driving mode based on an on / off signal of the mode selection switch 21, a switch signal of the shift device 22, and the like. Furthermore, the start control unit 29 is configured to start operating the stopped electric oil pumps (the oil pump OPfl for the left front wheel 1l and the oil pump OPfr for the right front wheel 1r) when it is predicted that the vehicle will travel in the four-wheel drive driving mode.

[0048] An example of the control by the controller 26 will be described with reference to the flow chart shown in FIG. 11. In the control example shown in FIG. 11, first, input data is acquired in step S1. The input data acquired here include the accelerator opening, vehicle speed, motor temperature, oil temperature, shift range, and driving mode. Next, it is determined whether the four-wheel drive driving mode is selected or set. Specifically, it is determined whether the above-mentioned track mode is selected or set (step S2), whether the drift mode is selected or set (step S3), or whether the manual sports mode is selected or set (step S4). These steps S2 to S4 can be determined based on a signal input from the mode selection switch 21 to the controller 26. The order of these determinations is not particularly limited and may be appropriate.

[0049] As described above, in the manual range mode, it is preferable to drive in four-wheel drive mode, so in addition to steps S2 to S4, it may be determined whether the manual range mode has been selected or set.

[0050] The above-mentioned track mode, drift mode, or manual sports mode is a driving mode selected under special circumstances such as circuit driving. Therefore, in normal circumstances, the above-mentioned driving modes are not selected, and the results of the judgments in steps S2 to S4 are "no." In that case, the two-wheel drive driving mode, which is a normal mode, is requested, or the two-wheel drive driving mode is set and the vehicle is running, so that only the oil pumps OPrr, OPrl provided corresponding to the rear wheels 2r, 2l, which are the driving wheels, are driven to actively supply oil to the motors Mrr, Mrl for the rear wheels 2r, 2l, thereby promoting their cooling (step S5). That is, the oil pumps OPfr, OPfl provided corresponding to the front wheels 1r, 1l are stopped or maintained in a stopped state. In that state, drive control is executed using the drive torque of the left and right rear wheels 2r, 2l (step S6). Then, return is made.

[0051] Here, "using the drive torque of the left and right rear wheels 2r, 2l" means that the drive torque of each of the rear wheels 2r, 2l is controlled by the motors Mrr, Mrl provided corresponding to each of the rear wheels 2r, 2l.

[0052] When the two-wheel drive mode is set, the motors Mfr, Mfl are not energized, so the motors Mfr, Mfl do not generate heat and do not require cooling. Therefore, by stopping or maintaining the stopped state of the oil pumps OPfr, OPfl provided for the front wheels 1r, 1l, the power consumption of the entire vehicle Ve can be reduced. That is, it is possible to improve energy efficiency while suppressing a decrease in the cooling performance of the motors Mrr, Mrl, which are the driving force sources in the two-wheel drive mode. In other words, by providing an electric oil pump that supplies oil only to the motors Mfr, Mfl that are stopped when traveling in the two-wheel drive mode, the oil pumps OPrr, OPrl provided for the rear wheels 2r, 2l only need to have a function of cooling the motors Mrr, Mrl, so the oil pumps OPrr, OPrl can be made smaller.

[0053] Even when traveling in the two-wheel drive mode, the front wheels 1r, 1l rotate, causing each rotating member constituting the drive unit Pf to rotate at a rotation speed according to the vehicle speed. That is, the mechanical oil pump OPm operates. Therefore, oil is supplied to the lubricated parts of the drive unit Pf, so that the durability of the drive unit Pf can be prevented from decreasing. In other words, oil is supplied only to the parts to which oil should be supplied, so that the power loss for driving the oil pump can be reduced.

[0054] On the other hand, if the result of any of the judgments in step S2 or S4 is "Yes", the vehicle is driven in four-wheel drive mode, or a switch from two-wheel drive mode to four-wheel drive mode is requested, so the oil pumps OPfr, OPfl, OPrr, and OPrl provided corresponding to the front and rear wheels are driven to actively supply oil to the motors Mfr, Mfl, Mrr, and Mrl to promote their cooling (step S7). In this state, drive control is performed using the drive torque of the front and rear four wheels (step S8). Then, the process returns.

[0055] Here, "drive control using the drive torque of the front and rear four wheels" refers to control in which the motors Mfr, Mfl, Mrr, and Mrl provided corresponding to each of the front and rear wheels 1r, 1l, 2r, and 2l are individually controlled to drive the vehicle Ve by individually controlling the drive torque of each wheel 1r, 1l, 2r, and 2l, and the torque distribution ratio between the front and rear wheels and the torque distribution ratio between the left and right wheels are appropriately controlled according to various requirements such as the required drive torque, the gradient angle of the road, and the turning radius.

[0056] The above-mentioned track mode, drift mode, or manual sports mode is usually set in special situations such as circuit driving, and the mode selection switch 21 is operated when the vehicle is stopped in the normal mode, and then the accelerator is operated according to the selected driving mode to drive the vehicle. In other words, after the driving mode is switched, the motors Mfr and Mfl are required to be driven. Therefore, in the above-mentioned control example, the operation of the mode selection switch 21 is used as a means for predicting that the vehicle will be driven in the four-wheel drive driving mode.

[0057] Then, when the mode selection switch 21 is operated as described above and it is predicted that the vehicle will travel in one of the travel modes of the track mode, the drift mode, or the manual sport mode, the oil pumps OPfr, OPfl that are stopped can be started to operate, so that the motors Mfr, Mfl can be supplied with oil and cooled before they are energized and generate heat. As a result, the oil pumps OPfr, OPfl can be kept operating when the vehicle travels in the four-wheel drive travel mode, so that the cooling performance of the motors Mfr, Mfl can be prevented from decreasing.

[0058] When operating the oil pumps OPfr, OPfl, OPrr, and OPrl as described above, it is preferable to determine the rotation speed of each oil pump OPfr, OPfl, OPrr, and OPrl, i.e., the amount of oil supplied to the motors Mfr, Mfl, Mrr, and Mrl, in accordance with the temperature of each motor Mfr, Mfl, Mrr, and Mrl. Specifically, it is preferable to set the rotation speed of the oil pump OPfr higher as the temperature of the motor Mfr is higher, set the rotation speed of the oil pump OPfl higher as the temperature of the motor Mfl is higher, set the rotation speed of the oil pump OPrr higher as the temperature of the motor Mrr is higher, and set the rotation speed of the oil pump OPrl higher as the temperature of the motor Mrr is higher.

[0059] In this way, by controlling the rotation speed of the oil pumps OPfr, OPfl, OPrr, OPrl in accordance with the temperatures of the motors Mfr, Mfl, Mrr, Mrl, it is possible to cool the motors Mfr, Mfl, Mrr, Mrl just enough and also to reduce power consumption.

[0060] In addition, the required driving torque tends to increase in the above-mentioned track mode, drift mode, manual sports mode, and manual range mode in that order. Therefore, it is preferable to set the rotation speeds of the oil pumps OPfr, OPfl, OPrr, and OPrl higher in the order of track mode, drift mode, manual sports mode, and manual range mode. In other words, it is preferable to store in the controller 26 a map shown in FIG. 12 that determines the rotation speeds of the oil pumps OPfr, OPfl, OPrr, and OPrl using the selected driving mode and the motor temperature as parameters, and to operate each of the oil pumps OPfr, OPfl, OPrr, and OPrl by referring to the map when driving in the four-wheel drive driving mode.

[0061] By controlling the rotation speeds of the oil pumps OPfr, OPfl, OPrr, and OPrl in accordance with the selected driving mode in this manner, the motors Mfr, Mfl, Mrr, and Mrl can be cooled just enough, and power consumption can be reduced.

[0062] In the electric vehicle according to the embodiment of the present invention, in the two-wheel drive mode, the rear wheels 2r, 2l are used as drive wheels, but the front wheels 1r, 1l may also be used as drive wheels. In that case, a mechanical oil pump is provided in the drive unit Pr, and the oil pumps OPrr, OPrl are stopped in the two-wheel drive mode.

[0063] Furthermore, the vehicle Ve may be provided with mechanical oil pumps in the drive units Pf and Pr, in which case the drive wheels when traveling in the two-wheel drive mode may be switched between the front wheels 1r, 1l and the rear wheels 2r, 2l as appropriate depending on the traveling environment, etc. When switching the drive wheels in the two-wheel drive mode in this way, it is sufficient to stop 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.

[0064] 2 does not show an oil pump for supplying oil to lubricated parts of the drive unit Pr, but the drive unit Pr may be configured to be appropriately lubricated by providing a mechanical oil pump, etc. Furthermore, the above-mentioned vehicle Ve may be configured to supply oil to lubricated parts of the drive unit Pr from oil pumps OPrr, OPrl because the rear wheels 2r, 2l function as drive wheels whether in two-wheel drive mode or four-wheel drive mode.

[0065] Furthermore, in the above-described control example, it is predicted that the vehicle will travel in the four-wheel drive driving mode based on a signal input from the mode selection switch 21 to the controller 26. However, it may also be predicted that the vehicle will travel in the four-wheel drive driving mode when it is predicted that the required driving torque will increase to a level that cannot be satisfied by the torque of the motors Mrr and Mrl alone, 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. In other words, it may be predicted that the vehicle will travel in the four-wheel drive driving mode based on a signal other than that of the mode selection switch 21. [Explanation of symbols]

[0066] 1r,1l front wheel 2r,2l rear wheel 10f,10r Oil 21 Mode selection switch 22 Shifting device 22b Shift lever 23 Neutral position detection switch 25 Paddle Switch 26 Controller 27 Pump selection section 28 Prediction Department 29 Starting control section Mfr, Mfl, Mrr, Mrl Motor OPfr, OPfl, OPrr, OPrl (electric type) oil pump OPm (mechanical) oil pump Pr,Pf drive unit Vehicle

Claims

1. a first motor that drives a first drive wheel which is one of a front wheel and a rear wheel; a first electric oil pump that supplies oil to the first motor; a second motor that drives a second drive wheel which is the other of the front wheel and the rear wheel; 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; a second drive unit that transmits torque from the second motor to the second drive wheel; and a mechanical oil pump that is operated by the first drive unit to supply the oil to the first drive unit, a controller that controls the first electric oil pump and the second electric oil pump; The controller: a pump selection unit that drives only the second electric oil pump out of the first electric oil pump and the second electric oil pump when the two-wheel drive traveling mode is selected; A prediction unit that predicts whether the vehicle will travel in the four-wheel drive mode; a start control unit that starts operating the first electric oil pump when the prediction unit predicts that the vehicle will be driven in the four-wheel drive mode. A cooling control device for an electric vehicle.

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

3. The cooling control device for an electric vehicle according to claim 1, The controller: The higher the temperature of the first motor, the more the amount of the oil supplied to the first motor by the first electric oil pump is increased, and the higher the temperature of the second motor, the more the amount of the oil supplied to the second motor by the second electric oil pump is increased. A cooling control device for an electric vehicle.

4. The cooling control device for an electric vehicle according to claim 1, The four-wheel drive driving mode includes a plurality of driving modes, The controller: An amount of the oil supplied by the first electric oil pump to the first motor and an amount of the oil supplied by the second electric oil pump to the second motor are controlled in accordance with the plurality of driving modes. A cooling control device for an electric vehicle.

5. The cooling control device for an electric vehicle according to any one of claims 1 to 4, The four-wheel drive driving mode includes at least one of a track mode in which turning performance is improved compared to the two-wheel drive driving mode, a drift mode in which driving precision is improved, a sports mode in which acceleration performance or power performance is improved, and a manual range mode in which the driving torque of the first motor and the second motor is controlled based on driving characteristics corresponding to a shift operation by a driver. A cooling control device for an electric vehicle.

Images