JPH0487835A - Differential limit control device for vehicle - Google Patents

Abstract

PURPOSE:To provide optimum cornering performance by controlling a differential limit amount by utilizing an iso-phase oil pressure at a rear steering angle control system to perform phase inversion control where a rear wheel is inverted from an opposite phase to an iso-phase, in a device to control a differential limit amount according to the magnitude of a clutch engaging force. CONSTITUTION:A rear wheel steering angle control system is provided with a rear wheel steering oil pressure generating means (b) to exert a control oil pressure, by means of which rear wheels are instantaneously steered to the opposite phase side during steering of front wheels and rear wheels are steered to the iso-phase side after enough yawing is produced, on a hydraulic cylinder (a) to steer rear wheels. A differential limit clutch (c) to limit a differential function between right and left wheels according to the magnitude of a clutch engaging force is located between rear wheels on both sides. In which case, a control valve (g) functioned so as to guide only an iso- phase oil pressure generated in a rear wheel steering oil passage (d) to an engaging oil chamber (e) of the differential limit clutch (c) is located in the middle of a clutch oil passage (f) for intercoupling a rear wheel steering oil passage (g), coupled to the hydraulic cylinder (a), an engaging oil chamber (e) of the differential limit clutch (c), and operation of the control valve is controlled by means of a clutch oil pressure control means (h).

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a differential limiting control device for a vehicle that controls a differential limiting amount in accordance with the magnitude of clutch engagement force based on externally applied controlled hydraulic pressure.

(Prior Art) Conventionally, as a vehicle differential limiting control device, for example, a device described in Japanese Patent Application Laid-Open No. 61-59044 is known.

This conventional source incorporates a differential limiting clutch in a position that limits the differential of a differential device such as a rear differential.
It shows a device in which an external hydraulic pressure generating device and the engagement oil chamber of a differential limiting clutch are connected by an oil path, and an electronic city control controller is connected to a hydraulic control valve installed in the middle of this oil path. A clutch engagement force is applied to the differential limiting clutch by outputting a valve drive control command to the hydraulic control valve based on predetermined vehicle information input to the controller, and the differential limiting amount is optimally controlled according to the vehicle condition. I try to do that.

(Problem to be Solved by the Invention) However, in the conventional electronically controlled device described above, a dedicated hydraulic pressure generator and an electronic controller are required to control the differential limit amount, which increases the weight and costs. The problem was that it was extremely disadvantageous.

Additionally, as a rear wheel steering angle control device, a device is known that steers the rear wheels in the same phase or in opposite phases when the front wheels are steered, and this rear wheel steering angle control device differentially limits the hydraulic pressure supplied to the hydraulic cylinders. One possibility is to apply it to the clutch, but in this case,
Hydraulic pressure is generated immediately after the front wheels are steered, and the rear wheel differential is limited when entering a corner, which prevents yawing and prevents the vehicle from turning smoothly.

The present invention has been made with attention to the above-mentioned problems, and provides a differential limiting control device for a vehicle that controls a differential limiting amount according to the magnitude of clutch engagement force by externally applied control oil pressure. The object of the present invention is to provide an advantage in terms of weight and cost, as well as optimal turning performance.

(Means for Solving the Problems) In order to solve the above problems, the vehicle differential limiting control device of the present invention provides a rear wheel steering angle control system that performs phase reversal control to reverse the rear wheels from opposite phases to the same phase. A means was provided to control the differential limiting amount using the in-phase hydraulic pressure of the two.

That is, as shown in the complaint correspondence diagram of Fig. 1, when the front wheels are steered, the rear wheels are momentarily steered to the opposite phase side when the front wheels are steered, and after sufficient yawing is obtained, the hydraulic cylinder a steers the rear wheels. A rear wheel steering hydraulic pressure generating means that provides control hydraulic pressure to steer the rear wheels in the same phase is provided between the left and right rear wheels, and limits the differential function between the left and right rear wheels according to the magnitude of the clutch engagement force. A differential limiting clutch C, a clutch oil passage f connecting a rear wheel steering oil passage d connected to the hydraulic cylinder a and a fastening oil chamber e of the differential limiting clutch C, and the rear wheel steering oil passage d. The clutch oil pressure control means controls the operation of a control valve 9 provided in the middle of the clutch oil passage f so as to guide only the in-phase oil pressure generated in the differential limiting clutch C to the engagement oil chamber e of the differential limiting clutch C.

(Function) When turning with front wheel steering, the rear wheels were momentarily steered to the opposite phase side with respect to the hydraulic cylinder a that steers the rear wheels in the rear wheel steering hydraulic pressure generating means, and sufficient yawing was obtained. rear,
Control hydraulic pressure is applied to steer the rear wheels to the same phase side.

Therefore, when entering a corner, a large rise in yaw rate is seen due to the reverse phase steering of the rear wheels, and even though sufficient yaw was obtained, the increase in yaw rate is suppressed by in-phase steering of the rear wheels, and the sideslip angle of the vehicle body is reduced. The vehicle's stability is ensured by preventing this from happening.

During this rear wheel steering control, the clutch oil pressure control means is provided in the middle of a clutch oil path f that connects the rear wheel steering oil path d connected to the hydraulic cylinder a and the engagement oil chamber e of the differential limiting clutch C. The operation of the control valve 9 is controlled, and only the in-phase oil pressure generated in the rear wheel steering oil path d is guided to the engagement oil chamber e of the differential limiting clutch C.

Therefore, the differential limiting clutch C provided between the left and right rear wheels has a differential limiting amount that is increased in proportion to an increase in the amount of rear wheel steering after the rear wheels begin to be steered to the same phase side. There is no differential restriction when entering a corner, and smooth turning performance is achieved by reverse-phase steering of the rear wheels, and differential restriction is applied after entering a corner, reducing vehicle stability due to rear wheels in-phase steering. The effect can be further increased.

In particular, when making a sharp turn due to sudden steering wheel operation, the differential limiting amount given when the rear wheels are steered in the same phase increases in proportion to the amount of rear wheel steering, and the increasing differential limiting effect ensures vehicle stability. Ru.

(Example) Embodiments of the present invention will be described below based on the drawings.

First, the configuration will be explained.

FIG. 2 is a system diagram of a main part of a differential limiting control device for a vehicle according to an embodiment, and FIG. 3 is an overall system diagram of a vehicle to which the differential limiting control device for a vehicle according to an embodiment is applied.

The vehicle to which the vehicle differential limiting control device of the embodiment is applied includes a rear wheel steering control system 3 that performs phase inversion control of the rear wheels 2 from opposite phase to the same phase with respect to the steering direction of the front wheels when steering the front wheels 1. (rear wheel steering hydraulic pressure generating means) is installed.

This rear wheel steering control system 3 includes, as an electronic control system, a vehicle speed sensor 4 and a steering angle sensor 5 that detect control input,
a rear wheel steering control section 6a that receives input from both sensors 4.5, calculates a rear wheel steering amount based on a predetermined control function, and converts it into a current output; and the rear wheel steering control section 6.
The pressure control valve 8 is provided with a first pressure control valve 8 and a second pressure control valve 8 which are operated in response to an output from a.

The hydraulic control system includes an oil pump 9, a pump pressure oil passage 10, a valve unit 11 in which the repressure control valves 7 and 8 are built-in, and a hydraulic pressure system in which a centering spring is built in to steer the rear wheels using hydraulic pressure. a cylinder 72, a first rear wheel steering oil passage 13 and a second rear wheel steering oil passage 14 connecting the valve unit 11 and the hydraulic cylinder 12, and a drain oil passage 15 connected to the valve unit 11; A reservoir tank 17 is provided to which the drain oil passage 15 and the pump suction oil passage 16 are connected.

Then, by this rear wheel steering control system 3, when the front wheels 1 are steered, the rear wheels 2 are momentarily steered to the opposite phase side, and when sufficient yawing is obtained, the rear wheels 2 are controlled to be steered to the same phase side. Rear wheel steering control is performed by applying hydraulic pressure.

In addition, the figure shows 18 cut-off valves, and both rear wheel steering oil passages 1
3.14 is provided in the middle of the rear wheel steering control section 6.
According to the command from a, it is opened during normal control and closed during failure.

The differential limiting control device for a vehicle according to the embodiment includes a rear differential 20 that distributes engine driving force to left and right rear wheels;
A differential limiting clutch 22 is built in the rear differential 20 and is connected to the hydraulic cylinder 12 to limit the differential function between the left and right rear wheels 2.2 by the differential gear 21 according to the magnitude of the clutch engagement force. A clutch oil passage 24 connecting both rear wheel steering oil passages 13, 14 and the engagement oil chamber 23 of the differential limiting clutch 22, and a first clutch oil passage provided midway between the two cylinder side clutch oil passages 24a, 24b. Input the steering angle signal from the on-off valve 25 and the second on-off valve 26 (control valve) and the steering angle sensor 5,
Both opening/closing valves 2 are arranged so that only the in-phase oil pressure generated in both rear wheel steering oil passages 13 and 14 is guided to the engagement oil chamber 23 of the differential limiting clutch 22 via the differential side clutch oil passage portion 24c.
5.26 Clutch hydraulic control section 6 that controls the operation
b (clutch hydraulic control means).

Note that the rear wheel steering control section 6a and the flange hydraulic control section 6b are mounted on the same controller 6 provided with a CPU and the like.

Next, the effect will be explained.

When turning by front wheel steering, the rear wheel steering control system 3 momentarily steers the rear wheels 2 to the opposite phase side with respect to the hydraulic cylinder 12 that steers the rear wheels 2, and after obtaining sufficient yawing, Control hydraulic pressure is applied to steer the wheels 2 to the same phase side.

That is, during slow steering and constant steering, the rear wheels 2 are steered in the same phase according to the steering angle of the front wheels 1, but during fast steering, the steering angular velocity and The contact wheels 2 are reversely controlled from anti-phase to in-phase in accordance with the steering angle acceleration, and the weighting of the anti-phase and in-phase steering angle components is changed in accordance with the vehicle speed.

Therefore, when entering a corner, a large rise in yaw rate is seen due to the reverse phase steering of rear wheels 2, and after sufficient yawing is obtained, the increase in yaw rate is suppressed by in-phase steering of rear wheels 2, causing the vehicle to skid. This prevents cornering and provides turning performance that combines crisp responsiveness and vehicle stability.

This debt export steering system? 11M includes a cylinder-side clutch oil passage portion 24a that connects both reverse wheel steering oil passages 13.14 connected to the hydraulic cylinder 12 and the engagement oil chamber 23 of the differential limiting clutch 22 in the clutch oil pressure control portion 6b;
The first on-off valve 25 and the second on-off valve 25 provided in the middle of the valve 24b
The operation of the opening/closing valve 26 is controlled, and both rear wheel steering oil passages 73.
Only the in-phase hydraulic pressure generated in either one of the differential clutches 74 is guided to the engagement oil chamber 23 of the differential limiting clutch 22.

That is, for example, when turning to the right, as shown in FIG. 2 is steered to the opposite phase side, the second opening/closing valve 26 is turned OFF and closed, so that the opposite phase oil pressure generated in the second rear steering oil passage 14 is diverted to the second opening/closing valve 26.
The engagement oil chamber 23 of the differential limiting clutch 22 communicates with the reservoir tank 17 by turning on the first on-off valve 25 and keeping it open.

When the first pressure control valve 7 is on the ON side and the second pressure control valve 8 is on the OFF side, and the rear wheels are being steered to the same phase side by the hydraulic cylinder 12, the first opening/closing valve 25 is turned on. By keeping it open, the in-phase oil pressure generated in the first rear wheel steering oil passage 13 is guided to the engagement oil chamber 23 of the differential limiting clutch 22. Furthermore, when turning left, the fifth
The same is true as shown in the figure.

Therefore, the differential limiting clutch 22 provided between the left and right rear wheels 2, 2 increases the differential limiting amount in proportion to the increase in the amount of rear wheel steering after the rear wheels 2 begin to be steered to the same phase side. Therefore, when entering a corner, the differential is not limited, and the rear wheels 2 are steered in reverse phase to achieve smooth steering, and after entering the corner, the differential is limited and the rear wheels are steered in the same phase to stabilize the vehicle. The performance can be further enhanced by the differential limiting effect.

In particular, when making a sharp turn due to a sudden steering operation, the differential limiting amount given when the rear wheels are steered in the same phase increases in proportion to the amount of rear wheel steering. be done.

As explained above, in the vehicle differential limiting control device of the embodiment, the effects described below can be obtained.

■ The differential limit amount is controlled by using the in-phase hydraulic pressure in the rear wheel steering angle control system 3, which performs phase reversal control to reverse the rear wheels 2 from opposite phase to the same phase. It is advantageous in terms of weight and cost compared to conventional equipment that requires a dedicated hydraulic generator and electronic controller for control, and can achieve optimal turning performance that combines smooth maneuverability and stability. .

■ Since the device uses the same phase hydraulic pressure as it is with the switching control using the double open/close valves 25 and 26, there is no need to perform hydraulic control using a proportional solenoid valve or a duty solenoid valve, and the clutch hydraulic control section 6b is also 0N-
A cost-effective control system can be achieved by simply performing OFF control.

Although the embodiment has been described above based on the drawings, the specific configuration is not limited to this embodiment.

(Effects of the Invention) As described above, the present invention provides a differential limiting control device for a vehicle that controls a differential limiting amount according to the magnitude of clutch engagement force by externally applied control oil pressure. This method is advantageous in terms of weight and cost because the in-phase oil pressure in the rear wheel steering angle control system, which performs phase reversal control that reverses the rear wheels from opposite phases to the same phase, is used to control the differential limit amount. At the same time, it is possible to obtain the optimum turning performance.

[Brief explanation of the drawing]

Fig. 1 is a claim correspondence diagram showing a differential limiting control device for a vehicle according to the present invention, Fig. 2 is a main system diagram showing a differential limiting control device for a vehicle according to an embodiment, and Fig. 3 is a diagram showing a differential limiting control device for a vehicle according to an embodiment. An overall system diagram of a vehicle to which the differential limiting control device is applied. Figure 4 is a rear wheel steering angle characteristic diagram when front wheels are steered using the rear wheel steering control system. Figure 5 is a diagram showing the characteristics of each valve when turning and when going straight. It is a figure which shows a control action table. a.-Hydraulic cylinder b...Rear wheel steering oil pressure generating means C.--Differential limiting clutch d.--Rear wheel steering oil passage e.. Closing oil chamber f.--Clutch oil passage 9.. Control valve h.・-Clutch hydraulic control means

Claims (1)

[Claims] 1) For the hydraulic cylinder that steers the rear wheels, when steering the front wheels, the rear wheels are momentarily steered to the opposite phase side, and after sufficient yawing is obtained, the rear wheels are turned to the in-phase side. Rear wheel steering hydraulic pressure generating means for supplying control hydraulic pressure for steering; a differential limiting clutch provided between the left and right rear wheels to limit the differential function between the left and right rear wheels according to the magnitude of clutch engagement force; a clutch oil passage that connects a rear wheel steering oil passage connected to the cylinder and the engagement oil chamber of the differential limiting clutch; and a clutch oil passage that connects the rear wheel steering oil passage connected to the cylinder and the engagement oil chamber of the differential limiting clutch; A differential limiting control device for a vehicle, comprising: clutch hydraulic pressure control means for controlling the operation of a control valve provided in the middle of a clutch oil passage so as to guide the clutch oil to the clutch oil passage.