JP4246485B2 - Vehicle differential rotation control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably control the rotating speed ratio of left-right wheels over a wide range by surely and quickly avoiding interference with an anti-lock brake system by simple control logic. <P>SOLUTION: Hydraulic pumps 3L and 3R are interposed between output shafts 10L and 10R and axles 11L and 11R of a differential device 2, and hydraulic passages 15 and 16 for communicating a delivery port and a suction port of the respective hydraulic pumps 3L and 3R are connected by a bypass passage 17 provided with an opening valve 18. When an ABS is not operated, the opening valve 18 is closed, and the rotating speed ratio of left-right wheels is stably controlled over a wide range by variably controlling the pump displacement volume so that the rotating speed ratio of the left-right wheels becomes the target rotating speed ratio based on a vehicle operation state. When the ABS is operated, interference with the ABS is prevented by freely rotating the hydraulic pumps 3L and 3R by opening the opening valve 18. When the ABS becomes non-operational from operational, the opening valve 18 is gradually closed, and is smoothly transferred to ordinary control while relieving a shock when closing the bypass passage 17. <P>COPYRIGHT: (C)2004,JPO&amp;NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a differential rotation control device for a vehicle that controls the rotation speed ratio of left and right wheels in a wide range and stably while avoiding interference with an antilock brake system.
[0002]
[Prior art]
Conventionally, various types of devices for distributing torque to the left and right wheels of a vehicle have been devised and put into practical use. As a typical example, there is a coupling that can variably control the transmission torque capacity between the left and right wheels, and the torque movement and the amount of torque movement are adjusted by controlling this coupling. Multi-plate clutch is widely adopted.
[0003]
Such devices are disclosed in, for example, Japanese Patent No. 2641724, Japanese Patent No. 2826580, and the like. In the devices disclosed in these patent documents, mechanical devices that transmit power from a power source to the left and right wheels are disclosed. Apart from the differential device, a gear pair for forcibly differentiating the left and right axes is installed, and the amount of torque movement between the left and right by the gear pair is adjusted by a hydraulic multi-plate clutch.
[0004]
[Patent Document 1]
Japanese Patent No. 2641724 gazette
[Patent Document 2]
Japanese Patent No. 2826580 [0006]
[Problems to be solved by the invention]
However, in the devices disclosed in Patent Document 1 and Patent Document 2, the upper limit of the controllable left / right wheel speed ratio is determined by the gear ratio of the gear pair, and the controllable width is limited by the mechanical configuration. In addition to this, in order to maintain the rotational speeds of the left and right wheels at the target rotational speed, feedback control with respect to increase / decrease in torque is required, which complicates the system.
[0007]
In particular, in a vehicle equipped with an anti-lock brake system (ABS), it is necessary to avoid interference with the wheel brake operation by the ABS, and if the control responsiveness decreases as the system becomes complicated, This may hinder smooth coordinated control and cause a sense of incongruity.
[0008]
The present invention has been made in view of the above circumstances, and it is possible to reliably and quickly avoid interference with the anti-lock brake system with a simple control logic, and stably control the rotation speed ratio of the left and right wheels over a wide range. It is an object of the present invention to provide a differential rotation control device for a vehicle that can be used.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the invention described in claim 1 is characterized in that two hydraulic pumps are connected to the left and right axles, respectively, and at least one is a variable displacement pump, the discharge ports and the suction ports of the two hydraulic pumps. Two hydraulic passages that communicate with the port to form a closed circuit, an open valve that opens and closes a bypass passage that bypasses the two hydraulic passages, and when the anti-lock brake system is not in operation, the open valve is closed to The two hydraulic pumps are reversibly operated as a pump and a motor by changing the displacement of the pump of the variable displacement pump so that the rotation speed ratio of the axle is a rotation speed ratio according to the driving state, and the anti-lock brake when the system is activated, and means for rotatably the two hydraulic pumps to the release valve is opened, the anti-lock braking system When returning to the non-actuated state from the operation, after adjustment as discharge amount of the two hydraulic pumps is equal, characterized in that close the release valve.
According to the second aspect of the present invention, two hydraulic pumps that are respectively connected to the left and right axles and at least one of which is a variable displacement pump, and the discharge port and the suction port of the two hydraulic pumps communicate with each other. Two hydraulic passages that form a closed circuit, an open valve that opens and closes a bypass passage that bypasses the two hydraulic passages, and when the antilock brake system is not in operation, the open valve is closed to rotate the left and right axles. When the anti-lock brake system is activated when the two hydraulic pumps are reversibly operated by pump and motor by changing the pump displacement of the variable displacement pump so that the ratio becomes the rotation speed ratio according to the operating state. Means for adjusting the discharge amounts of the two hydraulic pumps to be equal by rotating the two hydraulic pumps freely by opening the release valve. Characterized in that was.
[0010]
The invention of claim 1, wherein, when the anti-lock braking system is returned to the inoperative state from the operation, so closing the open valve after the discharge amounts of the two hydraulic pumps was adjusted to be equal, due to the closing of the bypass passage It is possible to relieve the impact and smoothly return to normal control.
[0011]
The invention of claim 2, wherein, when the anti-lock braking system is activated, the non-open valve because the discharge amounts of the two hydraulic pumps as open is previously adjusted to be equal, anti-lock braking system from the operating When activated, it is possible to quickly return to normal control while mitigating the impact associated with closing the bypass passage.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 relate to a first embodiment of the present invention, FIG. 1 is an explanatory diagram showing the configuration of a differential rotation control device, FIG. 2 is an explanatory diagram of a variable displacement hydraulic pump, and FIG. FIG. 4 is a flow chart showing the control process of the hydraulic pump by the controller, showing the relationship between the number ratio and the displacement ratio of the left and right pumps.
[0013]
The differential rotation control device according to the present invention controls the rotation speed ratio between the left and right wheels by using two hydraulic pumps (motors) that reversibly perform pump and motor operations with at least one of them as a variable displacement type. Can be distributed arbitrarily, and FIG. 1 shows an example applied to a drive wheel. In the figure, reference numeral 1 denotes a power transmission shaft for transmitting a driving force transmitted from an engine (not shown) through a transmission, and a differential device 2 is connected to the power transmission shaft 1. The differential rotation control device 4 mainly composed of the hydraulic pumps 3L and 3R is connected.
[0014]
The differential device 2 has a known mechanical configuration, and a crown pin 7 fixed to the outside of a rotatable differential case 6 meshes with a drive pinion gear 5 connected to the rear end of the power transmission shaft 1. The side gears 9 and 9 mesh with the pinion gears 8 and 8 that are pivotally supported in the differential case 6 and rotate together. The left and right output shafts 10L, 10R are fixed to the side gears 9, 9 and inserted through the differential case 6 so as to extend left and right.
[0015]
The left and right output shafts 10L and 10R of the differential device 2 are connected to the pump shafts of the left and right hydraulic pumps 3L and 3R, respectively, and are further connected to the left and right axles 11L and 11R via the pump shafts. Left and right drive wheels 12L and 12R are fixed to shaft ends of the left and right axles 11L and 11R.
[0016]
The left and right hydraulic pumps 3L and 3R are composed of, for example, a vane pump or a piston pump, and at least one of them is a variable displacement pump, and the discharge port and the suction port are connected by a hydraulic passage that forms a closed circuit. That is, the discharge port of the left hydraulic pump 3L and the suction port of the right hydraulic pump 3R are communicated via the hydraulic passage 15, and the discharge port of the right hydraulic pump 3R and the suction port of the left hydraulic pump 3L are hydraulically connected. Communication is made via a passage 16.
[0017]
The hydraulic passage 15 and the hydraulic passage 16 are connected to each other via a bypass passage 17, and an open valve 18 is interposed in the bypass passage 17. The release valve 18 is normally closed, and is opened when an ABS (anti-lock brake system) is operated to equalize the pressure in the hydraulic passages 15 and 16, as will be described later. This is to enable the 3R to freely rotate and prevent interference with the brake control by the ABS.
[0018]
The left and right hydraulic pumps 3L and 3R are not arranged in series between the output shafts 10L and 10R of the differential device 2 and the axles 11L and 11R, but are not limited to gear trains fixed to the output shafts 10L and 10R. You may arrange | position in parallel with the differential apparatus 2 via a chain etc. Further, when the differential rotation control device 4 is applied to the driven wheel, the differential device 2 is not necessary, and the pump shafts of the hydraulic pumps 3L and 3R are connected to the axles of the left and right driven wheels.
[0019]
FIG. 2 shows a configuration example of the hydraulic pumps 3L and 3R. In the figure, both are variable displacement hydraulic pumps using a vane pump in which a rotor 21 having a vane 20 rotates within a circular cam ring 22. . In this variable displacement hydraulic pump, the amount of eccentricity of the cam ring 22 with respect to the rotation center of the rotor 21 serving as a pump shaft is varied by an actuator 23. For example, the rotational operation of the actuator 23 such as a motor is controlled by a fulcrum 22a of the cam ring 22. The displacement of the pump (discharge volume) can be varied by converting it into a swinging motion centering on.
[0020]
The actuators 23 and 23 of the left and right hydraulic pumps 3L and 3R and the release valve 18 of the bypass passage 17 are connected to a controller 50 mainly composed of a microcomputer and the like, and are driven and opened / closed by signals from the controller 50. The Further, the controller 50 has an ABS control for preventing the wheel from being locked during sudden braking or braking on a slippery road surface such as an icy and snowy road so as to maintain directional stability, ensure steering performance, and shorten the braking distance. A unit 51 is connected, and an ABS signal indicating an ABS operation state is input from the ABS control unit 51, and various parameters indicating a vehicle operation state, for example, a steering angle of a steering wheel, wheel speeds of four front and rear wheels, an accelerator Parameters such as opening, engine speed, longitudinal acceleration, and lateral acceleration are input.
[0021]
In the controller 50, when the ABS signal from the ABS control unit 51 is OFF (ABS is not activated), the open valve 18 of the bypass passage 17 is kept closed so that the rotational speed ratio of the left and right wheels becomes the target rotational speed ratio. The left and right hydraulic pumps 3L and 3R are controlled. In this control, a control target value (target rotational speed ratio) for the rotational speed ratio of the left and right wheels at the time of traveling is set based on one or a plurality of parameters representing the vehicle operating state, and becomes the target rotational speed ratio. Thus, the displacement of the pump is variably controlled via the actuators 23, 23.
[0022]
That is, since the hydraulic pumps 3L and 3R rotate at the same speed as the wheels while the vehicle is running, assuming that the displacement volume per rotation of the left hydraulic pump 3L is VL and the rotation speed of the left wheel is NL, the hydraulic pump The 3 L discharge flow rate QL is expressed by the following equation (1). Similarly, assuming that the displacement volume per rotation of the right hydraulic pump 3R is VR and the rotation speed of the right wheel is NR, the discharge flow rate QR of the hydraulic pump 3R is expressed by the following equation (2).
QL = VL × NL (1)
QR = VR × NR (2)
[0023]
Here, the left hydraulic pump 3L and the right hydraulic pump 3R are configured such that their discharge ports and suction ports are connected to each other by closed circuit hydraulic passages 15 and 16, so that the left and right hydraulic pumps 3L, 3L, The relationship (QL = QR) that the discharge flow rate of 3R is the same holds, and the following equation (3) holds from the above-mentioned equations (1) and (2).
VL × NL = VR × NR (3)
[0024]
When the equation (3) is transformed with respect to the rotation speed ratio NR / NL of the left and right wheels, the following equation (3 ′) is obtained, and as shown in FIG. 3, the change in the displacement ratio VL / VR between the left and right pumps It is possible to obtain a characteristic in which the left / right wheel rotation speed ratio NR / NL changes linearly.
VL / VR = NR / NL (3 ')
[0025]
Accordingly, when the displacement volume of the hydraulic pump on either the left or right side is increased by a predetermined ratio, the opposite hydraulic pump acts as a motor, and the rotation speed of the opposite wheel can be increased by the same ratio. That is, by variably controlling the displacement of the pump, one axle 11L or 11R can be decelerated, while the other axle 11R or 11L can be accelerated and rotated relative to the differential device 2 to transmit power. The driving force transmitted from the shaft 1 and distributed to the left and right by the differential device 2 can be arbitrarily redistributed to the left and right axles 11L and 11R in accordance with the rate of acceleration / deceleration.
[0026]
As described above, one of the left and right hydraulic pumps 3L and 3R can be a variable displacement hydraulic pump and the other can be a fixed displacement hydraulic pump. The ability to vary the displacement volume of both is advantageous in terms of control width and control adaptability, and it is desirable that both the left and right hydraulic pumps 3L and 3R be variable displacement hydraulic pumps.
[0027]
On the other hand, when the ABS signal input from the ABS control unit 51 is turned on (ABS operation), the controller 50 opens the open valves 18 of the bypass passages 17 of the left and right hydraulic pumps 3L, 3R, and the hydraulic pumps 3L, 3R The rotation is free and interference with the brake control by ABS is prevented. Then, when the ABS operation is deactivated, the displacement volume of the left and right hydraulic pumps 3L, 3R is set to the target value, and then the release valve 18 is returned while the impact associated with the opening and closing of the bypass passage 17 is reduced. Performs processing and shifts to normal control.
[0028]
Hereinafter, control processing of the hydraulic pumps 3L and 3R by the controller 50 will be described with reference to a flowchart shown in FIG.
[0029]
As described above, during the execution of the normal control, the bypass passages 17 of the left and right hydraulic pumps 3L and 3R are closed by the release valve 18, and the displacement of each pump is controlled so that the target rotational speed ratio according to the operating state is obtained. Has been. When an ABS signal is input from the ABS control unit 51 in this control state, the process proceeds to step S1 to check whether the ABS signal is ON.
[0030]
As a result, when the ABS signal is ON, that is, when the ABS is activated, the routine proceeds from step S1 to step S2, immediately opening the open valve 18 of the bypass passage 17, and allowing the left and right hydraulic pumps 3L, 3R to freely rotate, Avoid interference with left and right wheel brake control by ABS. Then, while maintaining the open valve 18 in the open state, the process returns to step S1 to continue monitoring the ABS signal.
[0031]
After that, when the ABS is deactivated and the ABS signal is turned OFF, the process proceeds from step S1 to step S3 to set the target pump displacement ratio VL / VR for controlling to the left / right rotational speed ratio according to the operating state. In S4, the release valve 18 is gradually closed. For example, as shown in the figure, the opening valve 18 is reduced while mitigating the impact associated with the closing of the bypass passage 17 by, for example, relatively slowing the valve closing speed in the vicinity of reaching the fully closed position from the beginning of the fully opened position. After the opening valve 18 is fully closed, the process proceeds from step S4 to step S5 to return to the normal control.
[0032]
In this way, in the normal control when the ABS is not operating, the displacement of the pump can be varied using a variable displacement hydraulic pump, so that it can be controlled to an arbitrary rotational speed ratio, and the actual rotational speed ratio is the target rotational speed. When deviating from the number ratio, the hydraulic torque is automatically applied in a direction approaching the target speed ratio, so that stable control can be realized with extremely simple control logic.
[0033]
That is, in the technology that controls the torque as in the conventional hydraulic clutch and gear pair device, in order to set the rotational speed of the left and right wheels to the target rotational speed, feedback control with respect to increase / decrease in torque is necessary. In the differential rotation control device 4 according to the present invention, there is no need for feedback control, and stable driving control with a wide control range can be realized with an extremely simple control logic.
[0034]
Also, between the two hydraulic pumps, the differential rotational energy flows from the pump that wants to reduce the rotation to the pump that wants to increase the rotation. Compared to those requiring energy, there is an advantage that energy loss is small and efficiency is good.
[0035]
On the other hand, when the ABS is operated, the right and left hydraulic pumps 3L and 3R can be freely rotated immediately by opening the opening valve 18 of the bypass passage 17, and interference with the ABS can be avoided reliably and quickly. Moreover, when the ABS returns from normal operation to normal control, the displacement ratio of the left and right hydraulic pumps 3L, 3R is set to a target value for controlling the right / left rotational speed ratio according to the operating state. After the setting, the release valve 18 is gradually closed, so that the impact associated with the closing of the bypass passage 17 can be mitigated and the normal control can be smoothly performed. That is, smooth emphasis control can be realized by avoiding interference with the ABS reliably and quickly with a simple control logic.
[0036]
Next, a second embodiment of the present invention will be described. FIG. 5 is a flowchart showing a control process of the hydraulic pump by the controller.
[0037]
In the second mode, in the return processing from the ABS operation, the displacement volumes corresponding to the right and left wheel speed ratios at the time of ABS release are set for the left and right hydraulic pumps 3L and 3R that have been freely rotating until then. After adjusting the discharge amounts of the hydraulic pumps 3L and 3R to be equal, the release valve 18 of the bypass passage 17 is closed to smoothly shift to normal control while mitigating the impact when the bypass passage 17 is closed. Is.
[0038]
For this reason, in the second mode, as shown in FIG. 5, if the ABS signal input from the ABS control unit 51 is turned on during the normal control, the ABS signal is turned on in step S11 as in the first mode. If the ABS signal is ON, that is, if the ABS is activated, the process proceeds from step S11 to step S12, immediately opens the opening valve 18 of the bypass passage 17, and then returns to step S11 to monitor the ABS signal. Continue.
[0039]
Thereafter, when the ABS signal is turned OFF, the process proceeds from step S11 to step S13, and the wheel speeds of the left and right wheels are measured based on the signal of the wheel speed sensor, and the rotation speed ratio NR / NL of the left and right wheels is calculated in step S14. . Next, the process proceeds to step S15, in which the displacement ratios VL / VR of the left and right hydraulic pumps 3L, 3R corresponding to the calculated rotation speed ratio NR / NL of the left and right wheels are set, and each hydraulic pressure is set at this displacement volume ratio VL / VR. It adjusts so that the discharge amount of pump 3L, 3R may become equal.
[0040]
In step S16, the opening valve 18 of the bypass passage 17 is closed, and in step S17, the normal control is restored. After returning to the normal control, the target pump displacement ratio of the left and right hydraulic pumps 3L, 3R is set so that the left / right wheel speed ratio becomes the target speed ratio corresponding to the operating state.
[0041]
In the second mode, when returning from the ABS operation, the discharge flow rate of the left and right hydraulic pumps 3L and 3R is adjusted in advance before closing the open valve 18 of the bypass passage 17, so that the bypass passage 17 can alleviate the impact at the time of closing 17 and smoothly shift to normal control, and can prevent the generation of unnecessary yamments and stabilize vehicle behavior.
[0042]
Next, a third embodiment of the present invention will be described. FIG. 6 is a flowchart showing a control process of the hydraulic pump by the controller.
[0043]
In the third mode, when the ABS is operated, the bypass passages 17 of the left and right hydraulic pumps 3L and 3R are opened, and the discharge flow rates of the left and right hydraulic pumps 3L and 3R are made equal while monitoring the left and right wheel speeds. By performing follow-up control on the displacement of the pump, when the ABS becomes inoperative while mitigating the impact when the bypass passage 17 is closed, the control is quickly shifted to normal control.
[0044]
For this reason, in the third mode, as shown in FIG. 6, when the ABS signal input from the ABS control unit 51 is turned on during the normal control, it is checked in step S21 whether the ABS signal is turned on. When the signal is ON, that is, when the ABS is activated, the process proceeds from step S21 to step S22, and immediately the opening valve 18 of the bypass passage 17 is opened, and the wheel speeds of the left and right wheels are determined based on the signal of the wheel speed sensor in step S23. measure.
[0045]
Next, the process proceeds to step S24 to calculate the left / right wheel speed ratio NR / NL, and in step S25, the displacement ratio VL of the left and right hydraulic pumps 3L, 3R corresponding to the calculated left / right speed ratio NR / NL. / VR is set, and after adjusting the displacement volume ratio VL / VR so that the discharge amounts of the hydraulic pumps 3L and 3R become equal, the process returns to step S21 and the open valve 18 of the bypass passage 17 is maintained in the open state. However, the ABS signal and the left and right wheel speeds are continuously monitored.
[0046]
Then, when the ABS signal is turned OFF, the process proceeds from step S21 to step S26, the open valve 18 of the bypass passage 17 is immediately closed, and the normal control is restored in step S27. After returning to the normal control, the target pump displacement ratio of the left and right hydraulic pumps 3L, 3R is set so that the left / right wheel speed ratio becomes the target speed ratio corresponding to the operating state.
[0047]
In the third mode, when the ABS is operated, the discharge flow rates of the left and right hydraulic pumps 3L and 3R are adjusted in advance so that the release valve 18 is immediately closed when the ABS is deactivated from the activated state. There is no impact in the bypass passage 17, and the normal control can be immediately restored.
[0048]
【The invention's effect】
As described above, according to the present invention, simple control logic can reliably and quickly avoid interference with the anti-lock brake system, while stably controlling the rotation speed ratio of the left and right wheels over a wide range. Smooth cooperation control with the anti-lock brake system can be realized.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a configuration of a differential rotation control device according to a first embodiment of the present invention. FIG. 2 is an explanatory diagram of a variable displacement hydraulic pump. FIG. FIG. 4 is a flow chart showing the control process of the hydraulic pump by the controller according to the second embodiment of the present invention. FIG. 5 is a characteristic diagram showing the relationship between the ratio and the displacement ratio of the left and right pumps. FIG. 6 is a flowchart showing the control process of the hydraulic pump by the controller according to the third embodiment of the present invention.
3L, 3R Hydraulic pump 4 Differential rotation control device 11L, 11R Axle 15, 16 Hydraulic passage 17 Bypass passage 18 Release valve 50 Controller 51 ABS control unit

Claims (2)

Two hydraulic pumps respectively connected to the left and right axles, at least one of which is a variable displacement pump;
Two hydraulic passages that connect the discharge port and the suction port of the two hydraulic pumps to form a closed circuit;
An opening valve for opening and closing a bypass passage for bypassing the two hydraulic passages;
When the antilock brake system is not in operation, the release valve is closed and the displacement of the pump of the variable displacement pump is varied so that the rotational speed ratio of the left and right axles becomes the rotational speed ratio according to the operating state. Means for reversibly operating the two hydraulic pumps and the motor, and when the anti-lock brake system is operated, the open valve is opened to freely rotate the two hydraulic pumps ,
A differential rotation control device for a vehicle, wherein when the antilock brake system returns from an operation state to a non-operation state, the discharge amount of the two hydraulic pumps is adjusted to be equal, and then the release valve is closed. . Two hydraulic pumps respectively connected to the left and right axles, at least one of which is a variable displacement pump;
Two hydraulic passages that connect the discharge port and the suction port of the two hydraulic pumps to form a closed circuit;
An opening valve for opening and closing a bypass passage for bypassing the two hydraulic passages;
When the antilock brake system is not in operation, the release valve is closed and the displacement of the pump of the variable displacement pump is varied so that the rotational speed ratio of the left and right axles becomes the rotational speed ratio according to the operating state. When the two hydraulic pumps are operated reversibly and the antilock brake system is operated, the two hydraulic pumps are freely rotated by opening the release valve, and the discharge amounts of the two hydraulic pumps are equalized. A vehicle differential rotation control device comprising: means for adjusting in such a manner .

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