Vehicle with independently driven right / left wheel

Abstract

To prevent or suppress lubricating oil deviation due to lateral acceleration or a further decrease in oil level according thereto.SOLUTION: Provided is a vehicle with independently driven right / left wheels that comprises a motor 2r and an oil pump OPr for a right wheel 1r, and a motor 2l and an oil pump OPl for a left wheel 1l, and also comprises a controller 13 that controls the oil pumps OPr and OPl. The controller 13 comprises: a lateral acceleration detection part 13a for detecting lateral acceleration; and a pumping amount adjustment part 13b that performs at least either one of increasing an amount of oil pumped by one of the first oil pump and the second oil pump located on a front side in a direction of lateral acceleration, and decreasing an amount of oil pumped by the other oil pump located on a rear side in the direction of lateral acceleration, when the lateral acceleration is equal to or more than a predetermined value.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a vehicle configured to drive left and right wheels independently, and particularly to a vehicle provided with a device for cooling and lubricating a driving device provided for each of the left and right wheels.

Background Art

[0002] An example of a vehicle capable of driving left and right wheels independently of each other is described in Patent Document 1. The vehicle described in Patent Document 1 is configured in consideration of vehicle mountability, and motors are provided corresponding to each of the left and right wheels, and each motor is connected to the wheel via a differential mechanism. Further, a third rotating element of these differential mechanisms is connected so as to receive the torques applied thereto as reaction forces to each other.

[0003] Further, Patent Document 2 discloses an in-wheel motor vehicle having motors built in those wheels as an example of a vehicle capable of driving left and right wheels independently of each other. In the vehicle described in this Patent Document 2, the in-wheel motors of the left and right wheels are configured to be cooled by lubricating oil built in each of them, and the lubricating oil for cooling is configured so as not to be insufficient on the left and right by connecting those in-wheel motors with a lubricating oil piping.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Even in a vehicle configured to be driven by motors provided corresponding to the left and right wheels as described in Patent Document 1, since the motors inevitably generate heat, it is necessary to cool them. As in the in-wheel motor described in Patent Document 2, if lubricating oil is built into each in-wheel motor and the lubricating oil is circulated, the motor can be cooled. In that case, the loads on the left and right motors may be different, and accordingly, the heat generation amounts may be different between the left and right. However, as described in Patent Document 2, if the lubricating oil is circulated between the left and right motors through the lubricating oil piping, even if the required amount of lubricating oil for cooling increases in either one of the left and right motors, lubricating oil can be supplied from the other to avoid a shortage of lubricating oil. However, when the vehicle is running, lateral acceleration (acceleration in the vehicle width direction) may occur due to turning or the inclination of the road surface. In that case, the same acceleration acts on the lubricating oil as well. Therefore, if the above-described lubricating oil piping is provided, the lubricating oil will be biased to the left or right side of the vehicle. If the lubricating oil is continuously pumped up for cooling the motor in that state, on the side where the oil level has dropped due to the bias of the lubricating oil, the oil level (oil level) may further drop, causing the oil pump to suck in air or resulting in a shortage of lubricating oil accordingly.

[0006] The present invention has been made by paying attention to the above technical problems, and an object thereof is to provide a left and right wheel independent drive type vehicle capable of preventing or suppressing the bias of lubricating oil due to lateral acceleration or a further decrease in the oil level accompanying the bias.

Means for Solving the Problems

[0007] In order to achieve the above object, the present invention provides a left-right independent drive type vehicle including a first motor for driving a right wheel, a first oil pump for sucking oil from an oil pan and supplying the oil to the first motor, a second motor for driving a left wheel, and a second oil pump for sucking the oil from the oil pan and supplying the oil to the second motor, the vehicle being provided with a controller for controlling the first oil pump and the second oil pump, the controller including a lateral acceleration detection unit for detecting a lateral acceleration, and when the lateral acceleration is equal to or greater than a predetermined value, at least one of an increase in the amount of oil sucked by one of the first oil pump and the second oil pump located on the front side in the acting direction of the lateral acceleration and a decrease in the amount of oil sucked by the other oil pump located on the rear side in the acting direction of the lateral acceleration is executed by a suction amount adjustment unit.

Advantages of the Invention

[0008] According to the present invention, when the oil in the oil pan tends to flow to the right or left due to a lateral acceleration, the amount of oil sucked on the front side in the acting direction of the lateral acceleration, that is, on the side where the oil tends to flow and the oil level tends to rise, is increased, so that an increase in the oil level on the one side can be suppressed. Further, since the sucked oil flows back to the oil pan, a decrease in the oil level on the rear side in the acting direction of the lateral acceleration can be suppressed. Alternatively, since the amount of oil sucked on the rear side in the acting direction of the lateral acceleration, that is, on the other side where the oil tends to flow and the oil level tends to drop, is decreased, a decrease in the oil level on the other side can be suppressed.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0010] Next, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the embodiments described below are merely examples of implementing the present invention and do not limit the present invention.

[0011] The vehicle targeted by the present invention is a vehicle having at least a pair of left and right drive wheels, and a driving force source is provided for each of those drive wheels, and is configured so that the driving forces of the left and right drive wheels can be controlled independently of each other. Those drive wheels may be either front wheels or rear wheels, and FIG. 1 schematically shows an example of a front-wheel drive vehicle with the left and right front wheels 1r, 1l among the front wheels 1r, 1l and the rear wheels 2r, 2l as drive wheels. The vehicle Ve shown in FIG. 1 is provided with an electric motor or an electric motor having a power generation function (hereinafter, these are collectively referred to as a motor) as a driving force source, and motors 3r, 3l are provided corresponding to the right wheel 1r and the left wheel 1l, respectively.

[0012] An example of a drive unit P mainly composed of those motors 3r, 3l is schematically shown in FIG. 2. This drive unit P is composed of a pair of drive systems that drive the left and right front wheels 1r, 1l independently of each other, and since those drive systems have a bilaterally symmetric configuration, they will be described together without particularly specifying "right" or "left". In the following description, the suffix of the reference numeral indicates that "l" is for the left wheel and "r" is for the right wheel.

[0013] In the drive units P for the front wheels 1r and 1l, motors 3r and 3l are mounted with their rotation central axes oriented in the longitudinal direction of the vehicle Ve. Drive gears 4r and 4l are attached to the rotor shafts thereof, and these drive gears 4r and 4l mesh with counter drive gears 5r and 5l. The counter drive gears 5r and 5l have a larger diameter than the drive gears 4r and 4l, and thus these gear pairs constitute a speed reduction mechanism. Counter drive gears 6r and 6l, which are bevel gears, are provided so as to rotate integrally on the same axis as the counter drive gears 5r and 5l, and these counter drive gears 6r and 6l mesh with driven gears 8r and 8l, which are bevel gears integral with drive shafts 7r and 7l connected to the front wheels 1r and 1l. By making the driven gears 8r and 8l have a larger diameter than the counter drive gears 6r and 6l, these gear pairs can be used as a speed reduction mechanism.

[0014] These motors 3r and 3l, the speed reduction mechanism, and the respective bevel gears are housed in a liquid-tight manner inside a casing 9. Electric oil pumps OPr and OPl for supplying lubricating oil (oil) Oi for cooling and lubrication are provided for the motors 3r and 3l inside the casing 9. These oil pumps OPr and OPl are provided at appropriate locations on the vehicle Ve outside the casing 9, and are configured to suck up the oil Oi from an oil sump (oil pan) 10 and supply the oil Oi to the motors 3r and 3l through cooling oil passages 11r and 11l provided to penetrate the casing 9. Although not particularly shown, the oil Oi is configured to flow back from inside the casing 9 to the oil pan 10. Also, an oil cooler may be provided in the middle of the cooling oil passages 11r and 11l.

[0015] A power storage device (Bat) 12 is provided for power transfer between each of the above motors 3r, 3l and the oil pumps OPr, OPl. This power storage device 12 is mainly composed of a secondary battery such as a lithium-ion battery or an all-solid-state battery. Each of the motors 3r, 3l is, for example, a permanent magnet synchronous motor, and these motors 3r, 3l are connected to the power storage device 12 via a power controller Pc mainly composed of an inverter. Therefore, each of the motors 3r, 3l has its output torque and braking torque during energy regeneration individually controlled independently of each other. Note that the power controller Pc only needs to have functions independent of each other and may be configured as an integrated unit as a whole.

[0016] Similar to a normal vehicle, the vehicle Ve is configured to perform starting, acceleration, deceleration, stopping, and turning by the driver's operation. Therefore, although not particularly shown, operation devices such as an accelerator pedal, a brake pedal, a shift lever or shift paddles, a steering wheel, a switch for selecting a driving mode, and sensors for detecting operation states such as an accelerator opening, a brake pedal force (or depression amount), a selected driving mode, and a shift position, as well as sensors for detecting driving states such as a vehicle speed, longitudinal and lateral accelerations, and a steering angle are provided.

[0017] Based on the operation states and driving request states detected by these sensors, a controller 13 is provided to control the rotational speeds of the above-described electric oil pumps OPr, OPl, or the supply amount of the oil Oi from these oil pumps OPr, OPl to each of the motors 3r, 3l, and further the driving torque of each of the motors 3r, 3l and the regenerative braking torque (regenerative torque) generated by power generation. The controller 13 is mainly composed of a microcomputer, performs calculations according to a predetermined program using the input data and the data stored in advance, and is configured to output the result of the calculation as a control command signal to the above-described oil pumps OPr, OPl, the power controller Pc, etc.

[0018] Examples of the input data include various data such as vehicle speed, accelerator opening, shift position related to gear position, steering angle, mode such as power mode, normal mode, or economy mode, and braking operation state, which are input to the controller 13. Also, the pre-stored data includes a predetermined value for determining the magnitude of lateral acceleration, the change amount (increase amount or reduction amount) of the pumping amount (rotation speed of the oil pumps OPr, OPl) according to the lateral acceleration, and the duration of the control for changing the pumping amount according to the lateral acceleration.

[0019] In particular, the controller 13 is configured to control the amount of oil Oi supplied from each oil pump OPr, OPl to the motors 3r, 3l according to the state of the lateral acceleration. Specifically, when the lateral acceleration is large, the oil level in the oil pan 10 changes, and the oil level at the suction port or strainer (not shown in each case) where the oil pumps OPr, OPl suck up the oil Oi may become low. Therefore, in such a situation, the controller 13 controls the amount of oil pumped up by the oil pumps OPr, OPl. The controller 13 is provided with the functional configuration (or functional means) illustrated in FIG. 3 for performing such control.

[0020] The controller 13 includes a lateral acceleration detection unit 13a for detecting the lateral acceleration of the vehicle Ve. An example of the lateral acceleration is the centripetal acceleration when the vehicle Ve is turning, and another example is the gravitational acceleration in the vehicle width direction when the vehicle Ve is tilted to either the left or right. The lateral acceleration can be detected based on the data input from the acceleration sensor mounted on the vehicle Ve. Also, it can be calculated based on the vehicle speed and the steering angle. Alternatively, when the position information and map information of the vehicle Ve can be obtained, the lateral acceleration can also be configured to be calculated based on the change in the position of the host vehicle at each moment.

[0021] When the detected lateral acceleration is equal to or greater than a predetermined value, a pumping volume adjustment unit 13b for adjusting the pumping volume of the oil Oi by the oil pumps OPl and OPr is provided in the controller 13. The adjustment is for suppressing an excessive increase or decrease in the oil level due to the lateral acceleration. Therefore, the predetermined value for determining the magnitude of the lateral acceleration is a value set so as to determine the lateral acceleration that causes an excessive increase or decrease in the oil level, and can be obtained in advance by experiments, simulations, etc. and stored in the controller 13.

[0022] The adjustment of the pumping volume is at least one of an adjustment by increasing the pumping volume on the side where the oil level becomes high due to the lateral acceleration and an adjustment by decreasing the pumping volume on the side where the oil level becomes low, either on the left side or the right side of the vehicle Ve. For example, when a centrifugal acceleration is generated due to the vehicle Ve turning left, the oil Oi is pushed to the right side (the front side in the acting direction of the lateral acceleration) of the vehicle Ve in the oil pan 10, and the oil level tends to become high on the right side of the vehicle Ve. In such a case, the rotational speed of the right oil pump OPr whose suction port is located on the right side of the vehicle Ve is increased to increase its pumping volume. Instead of increasing the rotational speed of the right oil pump OPr, or together with increasing the rotational speed of the right oil pump OPr, the rotational speed of the left oil pump OPl (the side where the oil level tends to become low due to the lateral acceleration) is decreased to reduce the pumping volume.

[0023] The pumping volume adjustment unit 13b obtains and executes an increase in the pumping volume on one side or a decrease in the pumping volume on the other side by increasing or decreasing the output (e.g., rotational speed) of the oil pumps OPr and OPl and the duration thereof. For example, the increase amount, decrease amount, and duration of the output corresponding to the lateral acceleration are prepared and stored in advance as data, and the increase amount, decrease amount, and duration of the output corresponding to the lateral acceleration detected by the lateral acceleration detection unit 13a are obtained and used as control command signals for the respective oil pumps OPr and OPl.

[0024] An example of the control executed by the above-described controller 13 will be described with reference to FIG. 4. FIG. 4 is a flowchart for explaining an example of the control, and the routine shown here is repeatedly executed when the vehicle Ve is running. As described above, the detection data of the lateral acceleration is constantly input to the controller 13. In step S1, it is determined whether or not the detected lateral acceleration is equal to or greater than a predetermined value. The predetermined value serving as the criterion for the determination is as described above and is predetermined.

[0025] If the determination in step S1 is "No", the process returns without performing any particular control. On the contrary, if the determination result in step S1 is "Yes", the pumping amount of the oil Oi is adjusted (step S2). The content of the control for the adjustment is as follows. First, the oil pumps OPr and OPl for increasing or decreasing the pumping amount are determined based on the acting direction of the lateral acceleration. For example, when the lateral acceleration is generated by a left turn, the oil pump OPr on the right side (the front side in the acting direction of the lateral acceleration) is set as the oil pump for increasing the pumping amount, or the oil pump OPl on the left side (the rear side in the acting direction of the lateral acceleration) is set as the oil pump for decreasing the pumping amount. Next, the increase amount or decrease amount of the pumping amount is determined. In the case of an electric oil pump, the pumping amount (or discharge amount) increases or decreases according to the rotation speed, so the increase or decrease amount of the pumping amount may be determined as the increase or decrease amount of the rotation speed of the oil pumps OPr and OPl. The greater the lateral acceleration, the greater the amount of oil Oi bias or the change amount of the oil level between the right and left sides of the vehicle Ve. In order to suppress such oil Oi bias or excessive change in the oil level, the pumping amount is adjusted. Therefore, it is preferable that the increase or decrease amount of the pumping amount (rotation speed) be an amount corresponding to the lateral acceleration. For example, as shown in FIG. 5, a map in which the relationship between the lateral acceleration and the increase amount (or decrease amount) of the rotation speed of the oil pump OPr (or OPl) is predetermined is prepared in advance, and the increase amount (or decrease amount) of the rotation speed corresponding to the detected lateral acceleration is obtained from the map of FIG. 5.

[0026] Also, since the amount of oil Oi to be increased or decreased is an amount corresponding to the duration of the increased or decreased rotational speed, the duration of the control for increasing or decreasing the pumping amount is determined. FIG. 6 shows the pattern of increase (or decrease) in the rotational speed of the oil pump OPr (or OPl). After changing the rotational speed at a predetermined gradient toward the target rotational speed according to the lateral acceleration, the target rotational speed is maintained for a predetermined time, and then the rotational speed is changed at a predetermined gradient and returned to the original rotational speed. The time from the start to the end of such a change is the duration, which is prepared in advance as a map. Note that since the change amount (increase amount, decrease amount) of the rotational speed (pumping amount) is set according to the lateral acceleration as described above, the duration is changed according to the lateral acceleration.

[0027] After obtaining the adjustment amount of the pumping amount by the oil pumps OPr and OPl (the change amount of the rotational speed of the oil pumps OPr and OPl and its duration), a control command signal is output to the oil pumps OPr and OPl so as to realize the adjustment amount (step S3), and then the process returns. Note that in the embodiment of the present invention, at least one of the adjustment of the oil level by increasing the pumping amount and the adjustment of the oil level by decreasing the pumping amount may be executed, and it is not necessary to control both the left and right oil pumps OPr and OPl simultaneously.

[0028] According to the above-described control, inside the oil pan 10, the amount of oil Oi on the front side in the acting direction of the lateral acceleration is reduced, so that an excessive increase in the oil level at this portion is avoided or suppressed. Further, the pumped oil Oi returns to the oil pan 10 after cooling the motors 3r and 3l and the like, so that the oil Oi flows back and is supplied to the rear side in the acting direction of the lateral acceleration inside the oil pan 10, and a decrease in the oil level is suppressed. As a result, a situation where either of the oil pumps OPr and OPl sucks in air and, accordingly, the supply and cooling of the oil become insufficient is avoided or suppressed.

[0029] Note that the present invention is not limited to the above-described embodiments, and a vehicle provided with a drive motor and an oil pump for cooling the drive motor for each of the front and rear four wheels may be used. Further, the vehicle in the embodiment of the present invention may be an in-wheel motor vehicle in which a drive motor is provided inside a wheel.

Explanation of Signs

[0030] 1r, 1l Front wheels (right wheel, left wheel) 2r, 2l Rear wheels 3r, 3l Motors 4r, 4l Drive gears 5r, 5l Counter drive gears 6r, 6l Counter drive gears 7r, 7l Drive shafts 8r, 8l Driven gears 9 Casing 10 Oil pan 11r, 11l Cooling oil passages 12 Power storage device 13 Controller 13a Lateral acceleration detection unit 13b Pumping amount adjustment unit Oi Oil OPr, OPl Oil pumps P Drive unit Pc Power controller Ve Vehicle

Claims

【Claim 1】 A left-right independent drive type vehicle comprising a first motor for driving a right wheel, a first oil pump for pumping oil from an oil pan and supplying the oil to the first motor, a second motor for driving a left wheel, and a second oil pump for pumping the oil from the oil pan and supplying the oil to the second motor, comprising a controller for controlling the first oil pump and the second oil pump, wherein the controller comprises a lateral acceleration detection unit for detecting a lateral acceleration, and when the lateral acceleration is equal to or greater than a predetermined value, at least one of an increase in the oil pumping amount by one of the oil pumps located on the front side in the acting direction of the lateral acceleration and a decrease in the oil pumping amount by the other oil pump located on the rear side in the acting direction of the lateral acceleration, between the first oil pump and the second oil pump, and an oil pumping amount adjustment unit for performing at least one of them. A left-right wheel independent drive type vehicle characterized by the above.

Images