Cooling control device for electric vehicle

Abstract

The present invention relates to a cooling control device for an electric vehicle, which prevents or suppresses air suction during rapid acceleration and deceleration of an oil pump for cooling a motor for driving. The first oil pump supplies oil to the first motor for the front wheel. A second oil pump for supplying oil to the second motor for the rear wheel; and a controller (31) that controls the first oil pump and the second oil pump, the controller (31) being provided with: a detection unit (31a) that detects at least one of acceleration and deceleration when traveling by operating the first motor and the second motor; a sudden acceleration / deceleration determination unit (31b) that determines that either the acceleration or deceleration detected by the detection unit (31a) exceeds a predetermined threshold value; and a reduction control unit (31c) that, when it is determined that either the acceleration or the deceleration exceeds a predetermined threshold value, performs control so as to reduce the amount of oil supplied by an oil pump that supplies oil to one of the first motor and the second motor having a smaller load.

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] An example of an electric vehicle is described in Patent Document 1. The vehicle described in Patent Document 1 has an engine and a motor (or electric generator) with a power generation function, and is configured to drive the front wheels using the engine and a predetermined motor, and drive the rear wheels using another motor. Therefore, in the vehicle described in Patent Document 1, it is possible to select a two-wheel drive state in which the front wheels are driven by the engine and a predetermined motor, and a four-wheel drive state in which the rear wheels are driven by another motor. In addition, the front wheels can be driven only by a predetermined motor when the engine is stopped. In this case, the electric vehicle functions as a so-called battery-electric vehicle (BEV).

[0003] On the other hand, the motor that functions as a driving force source in an electric vehicle sometimes flows a large current according to the driving requirements and regenerative braking requirements of the electric vehicle. In addition, heat is generated due to inevitable iron loss, Joule loss, etc., and the heat generated increases according to the current. When the temperature of the motor becomes high, not only is the motor itself damaged or its durability reduced, but the output of the motor is also reduced, so the motor mounted on the electric vehicle needs to be cooled. Patent document 2 describes a hydraulic device that is configured to drive an electric oil pump to supply oil to the transmission and the driving motor for cooling when the hybrid vehicle is traveling only with the motor as the driving force source, so-called EV driving.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2015-168300

[0007] Patent Document 2: Japanese Patent Application Publication No. 2019-123387

[0008] In a vehicle equipped with a motor for driving the front wheels and a motor for driving the rear wheels as described in Patent Document 1, these motors are controlled independently of each other, so the operating states of the motors are different from each other. Therefore, if the electric oil pump is used to draw oil to cool the motor for driving as described in Patent Document 2, it is conceivable to provide an oil pump or a cooling device or cooling unit mainly composed of the oil pump corresponding to each motor.

[0009] When the front motor and the rear motor in an electric vehicle are cooled solely by oil, there are the following technical issues. That is, when the electric vehicle is running, acceleration and deceleration are inevitably generated, and with this, the inertial force acts on the oil used for cooling or lubrication, and the oil level (oil level) changes. When the oil level in the oil pan decreases due to such changes, the suction port or the coarse filter of the oil pump is exposed from the oil surface to the atmosphere, and as a result, the oil pump sometimes sucks in air. When the oil pump sucks in air, the amount of oil supplied to the motor and the lubrication parts is less than the expected amount, so insufficient cooling and insufficient lubrication may occur.

[0010] In the past, the above-mentioned technical issues in the following electric vehicle have not been studied, and in addition, the preferred technology for solving the issues has not been known in the past. The electric vehicle uses motors arranged corresponding to each wheel to drive the front and rear wheels and performs regenerative braking, and then uses oil pumps arranged correspondingly or a cooling device with an oil pump as the main body to cool these motors.

[0011] In order to deal with the above technical issues, it may be considered to increase the amount of oil in the oil pan in advance so that the oil level can be maintained at a certain height even when acceleration and deceleration occur. However, when the amount of oil is increased, the weight of the vehicle as a whole increases accordingly, which has the disadvantage of deteriorating energy efficiency (power consumption rate). Summary of the invention

[0012] Problems to be solved by the invention

[0013] The present invention is completed with a focus on the above-mentioned technical problems, and its purpose is to provide a cooling control device for an electric vehicle, which can appropriately control the oil pump when acceleration and deceleration occur, avoid or suppress the intake of air by the oil pump and the accompanying poor cooling of the motor, and can achieve an improvement in energy efficiency (power consumption rate) due to the lightweighting of the vehicle.

[0014] Means for solving problems

[0015] In order to achieve the above-mentioned purpose, the present invention is a cooling control device for an electric vehicle, the electric vehicle comprising: a first motor, the first motor driving a front wheel; a first oil pump, the first oil pump supplying oil to the first motor; a second motor, the second motor driving a rear wheel; and a second oil pump, the second oil pump supplying oil to the second motor, the load of the second motor being greater than the load of the first motor during acceleration, and the load of the first motor being greater than the load of the second motor during deceleration, the cooling control device for the electric vehicle being characterized in that the cooling control device for the electric vehicle comprises a controller for controlling the first oil pump and the second oil pump, The controller includes: a detection unit that detects at least one of the acceleration and deceleration when the first motor and the second motor are operated for driving; a sudden acceleration / deceleration determination unit that determines that either the acceleration or the deceleration detected by the detection unit exceeds a predetermined threshold value; and a reduction control unit that controls a reduction in the amount of oil supplied by the oil pump that supplies the oil to the motor with a smaller load between the first motor and the second motor when the sudden acceleration / deceleration determination unit determines that either the acceleration or the deceleration exceeds a predetermined threshold value.

[0016] In the present invention, the first motor and the second motor may be motors having a power generation function, and the load may be torques respectively output by the first motor and the second motor and regenerative torque generated by power generation.

[0017] In the present invention, the reduction control unit may be configured to reduce the amount of the oil supplied to the first motor by the first oil pump when the rapid acceleration / deceleration determination unit determines that the acceleration exceeds the threshold value.

[0018] In the present invention, the reduction control unit may be configured to reduce the amount of the oil supplied to the second motor by the second oil pump when the rapid acceleration / deceleration determination unit determines that the deceleration exceeds the threshold value.

[0019] In the present invention, the control for reducing the amount of oil supply may be a control for reducing a rotation speed of the oil pump that supplies the oil to the motor with the smaller load.

[0020] In the present invention, the controller may further include a torque control unit configured to reduce an output torque of the first motor when reducing an amount of the oil supplied to the first motor by the first oil pump.

[0021] In the present invention, the controller may further include a torque control unit configured to reduce an output torque of the second motor when reducing an amount of the oil supplied to the second motor by the second oil pump.

[0022] Effects of the Invention

[0023] According to the present invention, when the acceleration or deceleration exceeds a predetermined threshold value, the amount of oil supplied to the motor with a smaller load is reduced. That is, in the case of so-called rapid acceleration, the output torque of the second motor is increased, and the output torque of the first motor is not particularly large, so the load of the first motor is smaller than the load of the second motor. On the contrary, in the case of so-called rapid deceleration, the braking force is generated by the first motor, so its load is larger than the load of the second motor. When rapid acceleration or rapid deceleration occurs, the oil level (oil level) of the oil changes, and sometimes the oil level at the part where the oil pump draws oil will decrease, but since the oil is drawn less than the motor with a smaller load, the further decrease of the oil level can be suppressed to prevent or suppress the oil pump from sucking in air. In addition, even if the suction port is opened to the atmosphere, the air suction can be reduced. Therefore, there is no need to increase the amount of oil in advance, so the weight of the vehicle body can be reduced, and the energy efficiency (power consumption rate) can be improved accordingly.

[0024] In addition, in the present invention, when the above-mentioned torque control unit is provided, the output torque of the motor whose oil supply amount is reduced is reduced, so that the heat generation is reduced while the cooling of the oil is reduced, and as a result, the temperature increase of the motor and the oil can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 1 is a block diagram schematically showing a drive system of a four-wheel independent drive vehicle as an example of a vehicle in an embodiment of the present invention.

[0026] Figure 2 It is a schematic diagram showing an example of a drive unit on the rear wheel side.

[0027] Figure 3 It is a schematic diagram showing an example of a drive unit on the front wheel side.

[0028] Figure 4 It is a schematic diagram for explaining various mechanisms used for driving, stopping, and turning of a vehicle.

[0029] Figure 5 is a block diagram illustrating the functional structure and input signals of the controller.

[0030] Figure 6 This is a flowchart for explaining an example of control executed in the embodiment of the present invention.

[0031] Description of Reference Numerals

[0032] 1r, 1l front wheel

[0033] 2r, 2l rear wheel

[0034] 9f, 9r oil pan

[0035] 10f, 10r oil

[0036] 11rr, 11rl, 19fr, 19fl cooling oil circuit

[0037] 20 Power storage device

[0038] 21 Brake pedal

[0039] 22 Vehicle Stability Controller (VSC)

[0040] 23 Traction Control System (TCS)

[0041] 24 Anti-lock Braking System (ABS)

[0042] 28 Accelerator pedal

[0043] 29 Gear shifter

[0044] 30 Mode selector switch

[0045] 31a Detection Department

[0046] 31b Rapid acceleration / deceleration determination unit

[0047] 31c Lowering control unit

[0048] 31d Torque control unit

[0049] 31 Controller

[0050] Bfr, Bfl, Brr, Brl brake mechanism

[0051] Mfr, Mfl, Mrr, Mrl motors

[0052] OPfr, OPfl, OPrr, OPrl (electric) oil pump

[0053] OPm (mechanical) oil pump

[0054] Pf, Pr drive unit

[0055] PCf, PCr Power Controller

[0056] Pf, Pr drive unit

[0057] Vehicle DETAILED DESCRIPTION

[0058] 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.

[0059] The vehicle that is the object of the present invention is a vehicle having a total of four wheels, namely, two front wheels and two rear wheels, and a vehicle in which a driving force source is respectively provided for the two front wheels and the two rear wheels, and the two front wheels and the two rear wheels can be driven 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 vehicle that is the object of the present invention may also be a vehicle that is configured such that a driving force source is provided corresponding to each of the front and rear four wheels, and the driving torque and regenerative braking torque (regenerative torque) of each of the four wheels can be controlled independently of each other. Figure 1 Schematically shows an example of a four-wheel independent drive vehicle that can 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 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 composed of a motor and a gear reduction mechanism (transmission mechanism) as the main body.

[0060] 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" indicates for the front wheel, "l" indicates for the left wheel, and "r" indicates for the right wheel or for the rear wheel. In the case of 2 characters, the first character "f" indicates for the front wheel, "r" indicates for the rear wheel, the second character "r" indicates for the right wheel, and "l" indicates for the left wheel.

[0061] The drive unit Pr of the rear wheels 2r and 2l is equipped with motors Mrr and Mrl in such a manner that the rotation center axis of the motors Mrr and Mrl faces the front-rear direction of the vehicle Ve, and drive gears 3rr and 3rl are installed on the rotor shafts of the motors Mrr and Mrl, and the drive gears 3rr and 3rl are meshed with counter driven gears 4rr and 4rl. The diameter of the counter driven gears 4rr and 4rl is larger than that of the drive gears 3rr and 3rl, so these gear pairs constitute a speed reduction mechanism. Counter drive gears 5rr and 5rl, which are bevel gears, are provided on the same axis as the counter driven gears 4rr and 4rl in such a manner that they rotate as a whole, and the counter drive gears 5rr and 5rl are meshed with driven gears 7rr and 7rl, which are bevel gears that are integrally connected to the drive shafts 6rr and 6rl connected to the rear wheels 2r and 2l. By setting the driven gears 7rr and 7rl to have a larger diameter than the counter drive gears 5rr and 5rl, these gear pairs can be used as a speed reduction mechanism.

[0062] 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 positions 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. In addition, although not specifically shown in the figure, 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 also be provided in the middle of the cooling oil passages 11rr, 11rl.

[0063] exist Figure 31 shows an example of a drive unit Pf on the front wheel 1r, 1l side 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. By making the diameter of the counter driven gears 15fr, 15fl larger than the drive gears 12fr, 12fl mounted on the motors Mfr, Mrl, these 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, and the driven gears 18fr and 18fl are integrated with drive shafts 17fr and 17fl connected to the front wheels 1r and 1l. The driven gears 18fr and 18fl have a larger diameter than the counter drive gears 16fr and 16fl, so that the gear pair constitutes a speed reduction mechanism.

[0064] The motors Mfr and Mfl on the front wheels 1r and 11 are configured to be cooled by oil 10f in the same manner 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 oil 10f from the oil reservoir 9f and supply oil 10f to the motors Mfr and Mfl via cooling oil paths 19fr and 19fl. In addition, 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 paths 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 in the same manner as the oil pumps on the rear wheels 2r and 21.

[0065] 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 driven when the vehicle Ve is running, draws up the oil 10f from the oil reservoir 9f, and supplies the oil 10f to predetermined lubrication locations such as gears and bearings.

[0066] A power storage device (Bat) 20 is provided for transferring power between the above-mentioned motors Mfr, Mfl, Mrr, Mrl, and oil pumps OPfr, OPfl, OPrr, OPrl. The power 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 power storage device 20 via power controllers PCf, PCr 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 PCf and PCr can be independent of each other, or they can be configured as an integrated unit as a whole.

[0067] The vehicle Ve is equipped with various mechanisms for traveling, stopping, and turning, similarly to a normal vehicle. Figure 4 Its main structure is schematically described in FIG. A brake mechanism Bfr, ​​Bfl, Brr, Brl is provided on each wheel 1r, 1l, 2r, 2l. These brake mechanisms Bfr, ​​Bfl, Brr, Brl are configured to generate a braking force by being electrically controlled in addition to generating a braking force by operating a brake pedal 21. A vehicle stability controller (VSC) 22 is provided as a system for electrically controlling the braking force. The VSC 22 may be a structure similar to a conventionally known structure, for example, a system that combines a traction control system (TCS) 23 that operates the brake mechanisms Bfr, ​​Bfl, Brr, Brl in a manner that limits the driving force of each wheel, and an anti-lock braking system (ABS) 24 that reduces or releases the braking force of the brake mechanisms Bfr, ​​Bfl, Brr, Brl in a manner that avoids locking of each wheel. Therefore, when the control based on the VSC 22 is executed, the vehicle Ve generates acceleration and deceleration.

[0068] Figure 4 The front wheels 1r and 11 of the illustrated vehicle Ve are steered wheels, and are provided with a power steering mechanism (PS or EPS) composed of a steering wheel 25, a steering link 26, and an actuator 27 that assists steering force.

[0069] Furthermore, the vehicle Ve is provided with an accelerator pedal 28 for acceleration and deceleration, a shift device 29 for selecting a gear or driving gear, a mode selection switch 30 for selecting a driving mode, etc. These shift devices 29 and mode selection switches 30 may be a structure for selecting a gear (speed ratio) or a structure for selecting a shift gear using a lever provided on a floor, a center console, etc., a structure for switching the gear gear one by one by performing an upshift operation or a downshift operation in a manual position, or a structure for switching the shift gear one by one by operating a push button switch provided on a dashboard, a steering wheel, a steering column, etc.

[0070] In addition, the driving mode is mainly a control method for controlling the driving torque based on a predetermined benchmark, and includes a normal mode in which acceleration and energy efficiency (power consumption rate) become standard values, an economic mode in which power consumption rate is controlled preferentially over acceleration, a sports mode in which acceleration or power performance is improved, a tracking mode in which cornering performance is improved, and a drift mode in which driving accuracy is further improved. These driving modes are selected by operating the above-mentioned shift device 29 and the mode selection switch 30. In addition, driving modes other than the normal mode and the economic mode are generally selected by the driver requiring greater driving force and braking force, so a four-wheel drive state is set with the front and rear wheels 1r, 1l, 2r, and 2l as driving wheels. In addition, even in the normal mode, the four-wheel drive state is sometimes set in the case of a sudden acceleration operation or a sudden deceleration operation.

[0071] Various operating states or driving request states including the vehicle speed of the vehicle Ve are detected by sensors. Examples of such sensors include, although not specifically shown, a vehicle speed sensor, an accelerator opening sensor, an oil temperature sensor, a steering angle sensor, a shift position sensor, a brake sensor, a driving mode sensor, a motor speed sensor, a motor temperature sensor, and the like.

[0072] A controller 31 is provided, and the controller 31 controls the rotation speed of each of the electric oil pumps OPfr, OPfl, OPrr, OPrl or the amount of oil 10f, 10r supplied from the oil pumps OPfr, OPfl, OPrr, OPrl to each of the motors Mfr, Mfl, Mrr, Mrl, as well as the driving torque generated by each of the motors Mfr, Mfl, Mrr, Mrl, and the regenerative braking torque (regenerative torque) generated by power generation based on the operating state detected by these sensors, the driving state required by driving, etc. The controller 31 is mainly composed of a microcomputer, and is configured to use input data and pre-stored data to perform calculations according to a predetermined program, and output the results of the calculations as control command signals to the oil pumps OPfr, OPfl, OPrr, OPrl, the power controllers PCf, PCr, etc.

[0073] In particular, the controller 31 is configured to control the amount of oil 10f, 10r supplied from each oil pump OPfr, OPfl, OPrr, OPrl to the motors Mfr, Mfl, Mrr, Mrl according to the state of acceleration and deceleration. Specifically, when the acceleration or deceleration is large, the oil surface height (oil level) at each oil storage portion 9f, 9r changes, and the oil level at the suction port or the coarse filter (not shown) where the oil pumps OPfr, OPfl, OPrr, OPrl draw the oil 10f, 10r sometimes becomes low. In addition, the loads of the motors Mfr, Mfl, Mrr, Mrl are different, so the amount of oil drawn by the oil pumps OPfr, OPfl, OPrr, OPrl is controlled to match such conditions. In order to perform such control, the controller 31 has Figure 5 The functional structure (or functional mechanism) illustrated.

[0074] The controller 31 is provided with a detection unit 31a for detecting the acceleration and deceleration of the vehicle Ve. Since the speed of the vehicle Ve is always detected by the vehicle speed sensor, the detection unit 31a detects the acceleration and deceleration by time-differentiating the vehicle speed signal. Alternatively, in the case where the vehicle Ve is provided with an acceleration sensor, the detection unit 31a reads the acceleration or deceleration detected by the acceleration sensor. A rapid acceleration and deceleration determination unit 31b is provided, and the rapid acceleration and deceleration determination unit 31b determines whether a rapid acceleration or a rapid deceleration has occurred based on the acceleration or deceleration obtained by the detection unit 31a. Here, rapid acceleration and rapid deceleration are changes in the vehicle speed that produce acceleration or deceleration that affects the extraction of oil 10f, 10r by the oil pumps OPfr, OPfl, OPrr, OPrl by assuming that the change in the oil level caused by the inertial force has an effect. This determination can be performed by preparing a threshold value for acceleration and deceleration in advance and determining whether the acceleration or deceleration detected by the detection unit 31a exceeds the threshold value.

[0075] A reduction control unit 31c is provided, and the reduction control unit 31c reduces the amount of oil 10f, 10r drawn by each oil pump OPfr, OPfl, OPrr, OPrl or the amount of oil 10f, 10r supplied to each motor Mfr, Mfl, Mrr, Mrl. The oil pumps OPfr, OPfl, OPrr, OPrl that reduce the amount of oil drawn or supplied are predetermined according to rapid acceleration and rapid deceleration. When rapid acceleration is determined, the amount of oil drawn or supplied by the oil pumps OPfr, OPfl on the front wheels 1r, 11 is reduced. On the contrary, when rapid deceleration is determined, the amount of oil drawn or supplied by the oil pumps OPrr, OPrl on the rear wheels 2r, 21 is reduced. The reduction in the amount of oil drawn or supplied may be either a reduction or a stop of supply, and specifically, is performed by reducing the rotation speed of the oil pumps OPfr, OPfl, OPrr, OPrl. In addition, the reduction amount can be appropriately set in advance to a fixed value or a value corresponding to acceleration or deceleration. The reduction control unit 31c outputs the calculated reduction amount as a command signal to the oil pumps OPfr, OPfl, OPrr, and OPrl.

[0076] A torque control unit 31d is provided, and the torque control unit 31d reduces the load (output torque or regenerative braking torque) of the motor whose oil supply amount is reduced. In the case of rapid acceleration, the ground load of the front wheels 1r and 11 is reduced, so the driving torque of the front wheels 1r and 11 (the output torque of the motors Mfr and Mfl) is controlled to be a torque smaller than the driving torque of the rear wheels 2r and 21 (the output torque of the motors Mrr and Mrl). At the same time, the oil supply amount of the oil pumps OPfr and OPfl from the front wheels 1r and 11 is reduced, so the torque control unit 31d reduces the driving torque of the front wheels 1r and 11 (the output torque of the motors Mfr and Mfl) based on the reduction in cooling. Conversely, in the case of rapid deceleration, the ground load of the rear wheels 2r and 21 is reduced, so the braking torque of the rear wheels 2r and 21 (the regenerative torque of the motors Mrr and Mrl) is controlled to be a torque smaller than the braking torque of the front wheels 1r and 11 (the regenerative torque of the motors Mfr and Mfl). That is, the load becomes smaller. At the same time, the oil supply from the oil pumps OPrr and OPrl on the rear wheels 2r and 2l is reduced, so the torque control unit 31d reduces the braking torque of the rear wheels 2r and 2l (the regenerative torque of the motors Mrr and Mrl) based on the reduction in cooling. In addition, the reduction amount of the torque of each motor Mfr, Mfl, Mrr and Mrl can be preset to a fixed value, or can be set to a reduction amount corresponding to the degree of reduction based on the cooling of the oil 10f and 10r. The torque control unit 31d outputs the reduction amount of the torque calculated in this way to the above-mentioned power controllers PCf and PCr.

[0077] As data for performing the above control, various data are input to the controller 31. Examples of the input signals are as follows. A vehicle speed signal, an accelerator opening signal, a shift position signal, and a steering angle signal are input to the controller 31. The vehicle speed signal is a signal obtained by detecting the rotation speed of a member such as a drive shaft that rotates during driving. In addition, the accelerator opening signal is a signal obtained based on the pedal angle or pedal force of the aforementioned accelerator pedal 28, and is a signal indicating the drive requirement. The shift position signal is a signal indicating the shift position selected by operating the aforementioned shift device 29, and is a signal indicating the drive (D) position controlled in the normal mode, the manual position or the brake (B) position that can be manually operated to shift up and down, and the L gear position and the "2" gear position that maintain the drive torque at a large torque at a high vehicle speed. When a position is selected such that the upper limit of the drive torque, the engine brake (drive force source brake) is appropriately exerted, etc., the shift position signal is input to set the four-wheel drive state. The steering angle signal is a signal obtained by detecting the rotation angle of the steering wheel 25, and is input as a signal indicating that the vehicle Ve is turning. In a vehicle capable of controlling the torque of four wheels individually, the torque of the four wheels is sometimes controlled to improve the turning performance, so the steering angle signal is input to perform this control.

[0078] In addition, the mode selection signal, the brake signal, the upshift (+) signal, and the downshift (-) signal are input to the controller 31. The mode selection signal is a signal selected by the aforementioned mode selection switch 30 and indicates the driving mode. As mentioned above, in driving modes other than the normal mode and the economic mode, in order to control in a manner that gives priority to improving acceleration (power performance), cornering performance, etc., the driving torque and brake torque of each wheel 1r, 1l, 2r, 2l are sometimes controlled individually and actively. Therefore, in order to determine whether it is a driving mode that performs such control, a mode selection signal is input. The brake signal is a signal output according to the pedaling amount and pedaling force when the aforementioned brake pedal 21 is stepped on. In addition, it is a signal output when the braking force of the brake mechanism Bfr, ​​Bfl, Brr, Brl is controlled by using the VSC22. The aforementioned judgment of rapid deceleration can also be performed based on this brake signal.

[0079] The upshift (+) signal and the downshift (-) signal are signals output when the shift position and the speed gear are switched by manual operation, for example, by selecting the manual position by using the aforementioned shift device 29 and operating the shift lever (not shown) from the position to the upshift (+) side or the downshift (-) side. Alternatively, in the state where the manual gear position is selected, the signal is output by operating, for example, the upshift (+) switch, the downshift (-) switch or the paddle provided on the steering wheel 25 or in the vicinity thereof. The driving state in which the shift position and the speed gear are switched by such manual operation is a state requiring greater acceleration or power performance than the normal mode, and further requiring cornering performance, so it is desired to set the four-wheel drive state, and for this purpose, the upshift (+) signal and the downshift (-) signal are input to the controller 31. In addition, the oil temperature signal is input as data for controlling the supply amount of the oil 10f, 10r based on the oil pumps OPfr, OPfl, OPrr, OPrl or the rotation speed of the oil pumps OPfr, OPfl, OPrr, OPrl.

[0080] exist Figure 6 An example of the control performed by the controller 31 during sudden acceleration and sudden deceleration is shown in a flowchart. The control routine shown here is repeatedly executed when the vehicle Ve is in a four-wheel drive state, that is, the front and rear oil pumps OPfr, OPfl, OPrr, OPrl are all in operation to pump oil 10f, 10r for driving. In this case, the drive torque and regenerative braking torque of the front wheels 1r, 1l, 2r, 2l are controlled by a drive control device generally provided in a four-wheel drive vehicle according to the vehicle speed, drive requirement, etc. Figure 6 In the control shown, first, the data required for the control is taken in (step S1). When listing examples of the data to be taken in, the accelerator opening, vehicle speed, motor temperature, oil temperature, gear shift position, etc. are taken in. Next, it is determined whether it is a sudden acceleration state (step S2) and a sudden deceleration state (step S3). As mentioned above, it is possible to determine whether it is a sudden acceleration state based on whether the detected acceleration exceeds a predetermined threshold value. In addition, similarly, it is possible to determine whether it is a sudden deceleration state based on whether the detected deceleration exceeds a predetermined threshold value. In addition, the absolute values ​​of the thresholds used to determine sudden acceleration and sudden deceleration may be the same, or they may be different. In addition, the order of determining the sudden acceleration state and the sudden deceleration state may be one side first.

[0081] If the determination result in step S2 is "yes" because the vehicle Ve is accelerating and in a rapid acceleration state where the acceleration exceeds the threshold, control is performed to reduce the rotation speed of the oil pumps OPfr, OPfl on the front wheels 1r, 11 side (step S4). That is, the amount of oil 10f drawn from the oil pan 9f by the oil pumps OPfr, OPfl on the front wheels 1r, 11 side or the amount of oil 10f supplied to the motors Mfr, Mfl driving the front wheels 1r, 11 is reduced.

[0082] In the rapid acceleration state, the ground load of the front wheels 1r and 11 is reduced, so the driving torque of the front wheels 1r and 11, that is, the output torque of the motor Mfr and Mfl on the front wheels 1r and 11 is controlled to be smaller than the output torque of the motor Mrr and Mrl on the rear wheels 2r and 21. That is, the load of the motor Mfr and Mfl on the front wheels 1r and 11 is smaller than the load of the motor Mrr and Mrl on the rear wheels 2r and 21. Therefore, the necessity or cooling requirement of the motor Mfr and Mfl on the front wheels 1r and 11 is lower than that of the motor Mrr and Mrl on the rear wheels 2r and 21, so the supply amount of the oil 10f for cooling and lubrication is reduced. In this case, since it is in the rapid acceleration state, the oil level in the oil pan 9f changes due to the inertia force, and the oil level at the part where the oil pumps OPfr and OPfl draw the oil 10f may sometimes decrease. However, since the amount of oil 10f drawn by the oil pumps OPfr and OPfl is reduced, further decrease in the oil level can be avoided or suppressed. As a result, suction of air by the oil pumps OPfr and OPfl can be avoided, and even if suction occurs, it can be limited to a small amount.

[0083] Together with the control of step S4, the driving torque of the front wheels 1r and 11 is reduced (step S5). That is, the output torque of the motors Mfr and Mfl on the front wheels 1r and 11 is reduced. Then return. As a result, the heat generation of the motors Mfr and Mfl is reduced, so even if the supply of oil 10f is reduced, the increase in motor temperature can be avoided or suppressed. In addition, the required driving force as a whole of the vehicle Ve is calculated based on the vehicle speed, accelerator opening, etc., and the driving torque of the front and rear wheels 1r, 11, 2r, and 21 is controlled in a manner to meet the required driving force. Therefore, when the driving torque of the front wheels 1r and 11 is reduced, the driving torque of the rear wheels 2r and 21 is increased accordingly, so that the driving force as a whole of the vehicle Ve is maintained to meet the required driving force.

[0084] On the other hand, if the vehicle Ve is decelerated and is in a rapid acceleration state in which the deceleration exceeds the threshold value, and the determination result in step S3 is "yes", control is performed to reduce the rotation speed of the oil pumps OPrr and OPrl on the rear wheels 2r and 21 (step S6). That is, the amount of oil 10r drawn from the oil pan 9r by the oil pumps OPrr and OPrl on the rear wheels 2r and 21 or the amount of oil 10r supplied to the motors Mrr and Mrl driving the rear wheels 2r and 21 is reduced.

[0085] In the rapid deceleration state, the ground load of the rear wheels 2r and 2l is reduced. In addition, in order to more effectively regenerate energy based on the front wheels 1r and 1l, the braking torque of the rear wheels 2r and 2l, that is, the regenerative braking torque of the motors Mrr and Mrl on the rear wheels 2r and 2l is controlled to be smaller than the regenerative braking torque of the motors Mfr and Mfl on the front wheels 1r and 1l. That is, the load of the motors Mrr and Mrl on the rear wheels 2r and 2l is smaller than the load of the motors Mfr and Mfl on the front wheels 1r and 1l. Therefore, the necessity or cooling requirement of the motors Mrr and Mrl on the rear wheels 2r and 2l is lower than that of the motors Mfr and Mfl on the front wheels 1r and 1l, so the supply amount of the oil 10r for cooling and lubrication is reduced. In this case, since it is in the rapid deceleration state, the oil level in the oil pan 9r changes due to the inertial force, and the oil level at the part where the oil pumps OPrr and OPrl draw the oil 10r may sometimes decrease. However, since the amount of oil 10r drawn by the oil pumps OPrr and OPrl is reduced, further decrease in the oil level can be avoided or suppressed. As a result, suction of air by the oil pumps OPrr and OPrl can be avoided, and even if suction occurs, it can be limited to a small amount.

[0086] Together with the control of step S6, the braking force of the rear wheels 2r and 2l is reduced (step S7). That is, the regenerative braking torque of the motors Mrr and Mrl on the rear wheels 2r and 2l is reduced. Then return. As a result, the heat generation of the motors Mrr and Mrl is reduced, so even if the supply of oil 10r is reduced, the increase in motor temperature can be avoided or suppressed. In addition, the required braking force of the vehicle Ve as a whole is calculated based on the braking operation amount, etc., and the braking force of the front and rear wheels 1r, 1l, 2r, 2l is controlled in a manner to meet the required braking force. Therefore, when the braking force of the rear wheels 2r and 2l is reduced, the braking force of the front wheels 1r and 1l is increased accordingly, so that the braking force of the vehicle Ve as a whole is maintained to meet the required braking force.

[0087] In addition, when the judgment result in step S3 is "No" because it is not in any state of rapid acceleration or rapid deceleration, no special control is performed and the state returns. In this case, based on the driving state or driving requirement state of the vehicle Ve such as vehicle speed, accelerator opening or brake operation amount, the two-wheel drive state or the four-wheel drive state is selected, and the driving force and braking force of each wheel 1r, 1l, 2r, 2l, that is, the output torque and regenerative braking torque of each motor Mfr, Mfl, Mrr, Mrl are controlled. This can be performed by a control system for driving that an electric vehicle usually has.

Claims

1. A cooling control device for an electric vehicle, the electric vehicle comprising: a first motor, the first motor driving a front wheel; a first oil pump, the first oil pump supplying oil to the first motor; a second motor, the second motor driving a rear wheel; and a second oil pump, the second oil pump supplying oil to the second motor, the load of the second motor being greater than the load of the first motor during acceleration, and the load of the first motor being greater than the load of the second motor during deceleration, the cooling control device for the electric vehicle being characterized in that: The cooling control device for an electric vehicle includes a controller for controlling the first oil pump and the second oil pump. The controller has: a detection unit configured to detect at least one of acceleration and deceleration when the first motor and the second motor are operated for traveling; a sudden acceleration / deceleration determination unit configured to determine whether one of the acceleration and the deceleration detected by the detection unit exceeds a predetermined threshold value; and A reduction control unit, which controls the oil supply amount of the oil pump that supplies the oil to the motor with a smaller load between the first motor and the second motor to be reduced when the rapid acceleration / deceleration determination unit determines that either the acceleration or the deceleration exceeds a predetermined threshold value.

2. The cooling control device for an electric vehicle according to claim 1, characterized in that: The first motor and the second motor are motors with a power generation function. The load is torque outputted by the first motor and the second motor, respectively, and regenerative torque generated by electric power generation.

3. The cooling control device for an electric vehicle according to claim 1 or 2, characterized in that: The reduction control unit reduces the amount of the oil supplied to the first motor by the first oil pump when the rapid acceleration / deceleration determination unit determines that the acceleration exceeds the threshold value.

4. The cooling control device for an electric vehicle according to claim 1 or 2, characterized in that: The reduction control unit reduces the amount of the oil supplied to the second motor by the second oil pump when the rapid acceleration / deceleration determination unit determines that the deceleration exceeds the threshold value.

5. The cooling control device for an electric vehicle according to claim 1 or 2, characterized in that: The control for reducing the amount of oil supply is control for reducing the rotation speed of the oil pump that supplies the oil to the motor with the smaller load.

6. The cooling control device for an electric vehicle according to claim 1 or 2, characterized in that: The controller further includes a torque control unit configured to reduce an output torque of the first motor when reducing an amount of the oil supplied to the first motor by the first oil pump.

7. The cooling control device for an electric vehicle according to claim 1 or 2, characterized in that: The controller further includes a torque control unit configured to reduce an output torque of the second motor when reducing an amount of the oil supplied to the second motor by the second oil pump.

Images