JPS63215466A - Rear wheel steering device for automobile equipped with antiskid controller - Google Patents

Abstract

PURPOSE:To maintain the traveling stability of a car by steering rear wheels so that the moment for turning the car is offset, when the phase of the antiskid control pattern deflects between the right and left wheels and said moment is generated. CONSTITUTION:The brake hydraulic pressure Pa lowers until the second control valve 10b in a cross piping B system is opened after the decompression timing from a brake device is deflected between both cross piping A and B systems, and the second control valve 10a in the cross piping A system is opened, and the brake hydraulic pressure Pb increases. Therefore, the brake pressure larger than those applied onto the wheels 4 and 5 belonging to the cross piping A system acts onto the wheels 3 and 6 belonging to the cross piping B system, Further, since the load distribution between the front and rear wheels is larger on the front wheel side, the moment Mb in the counterclock wise direction due to the brake power is generated. A rear wheel steering control 15 turns the rear wheels 5 and 6 in the counterclockwise direction by intermittently opening and closing a decompression valve 18L and a pressurizing valve 19R according to the difference between the brake hydraulic pressure Pb and Pa for the moment Mb, and the stability of the wheel is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rear wheel steering system for a motor vehicle with an anti-skid control system.

Conventional technology In hydraulic brake systems for automobiles, during braking when the brake pedal is depressed and hydraulic pressure is supplied from the master cylinder to the wheel cylinders, the rate and amount of decrease in wheel speed relative to the vehicle body speed is detected, and based on this, hydraulic pressure is supplied to the wheel cylinders. Various anti-skid devices have been developed in the past, which alternately control the depressurization and pressurization of the brake fluid pressure to perform effective braking without locking the wheels and losing direction maintenance. It has already been published in Publication No. 60-61354.

Furthermore, in the field of automobiles, a front and rear wheel steering type automobile in which both the front wheels and the rear wheels are steered by operating the steering wheel has already been developed and is publicly known (Japanese Patent Laid-Open No. 58-2
(See Publication No. 0565).

Problems to be Solved by the Invention In the above-mentioned anti-skid device, a pressure increasing valve (normally open) and a pressure reducing valve (normally closed) are installed in the hydraulic line that supplies brake fluid pressure to the brake equipment of each wheel. The control unit issues a signal based on the wheel speed signal of the wheel speed sensor that detects the speed of each wheel, energizes the pressure valve to close it, and stops the supply of fluid pressure to the brake device, and then turns the pressure reduction valve on. The hydraulic pressure in the brake device is reduced by energizing and opening the valve, and then, after waiting for the wheel speed to recover, the power supply to the pressurizing valve is cut off and the valve is opened to pressurize the brake device. With an alternating control pattern,
The system provides effective braking to prevent wheels from locking, so if there is a difference in the coefficient of friction of the road surface on which each wheel is located, the control pattern that alternately repeats depressurization and pressurization will change the phase for each wheel. However, the yawing moment (coupled force that tends to turn the vehicle) due to the phase shift of the control pattern is normally followed by the driver's steering wheel operation as necessary.

The present invention relates to a rear wheel steering system for an automobile equipped with an anti-skid control device that minimizes the influence of the yawing moment that occurs during anti-skid operation. During braking, when hydraulic pressure is supplied from the cylinder to the brake equipment of each wheel, the hydraulic pressure is released as the wheel speed decreases relative to the vehicle body speed, reducing the braking force, and then completely preventing the wheel speed from recovering due to road reaction force. In automobiles equipped with anti-skid control devices that use a control system that repeats a control pattern in which hydraulic pressure is supplied and pressurized again, a rear wheel steering actuator is installed to steer the rear wheels, and a rear wheel steering angle control circuit is configured to control the rear wheels. The rear wheel steering angle control circuit is configured to determine the direction and steering angle in which the vehicle should be steered, issue an output signal to the rear wheel steering actuator, and operate the rear wheels to steer the rear wheels. The present invention is characterized in that it is configured to generate an output signal for steering the rear wheels in a direction that cancels out the turning moment based on a signal that detects a turning moment based on a difference in hydraulic pressure fluctuations.

Effect As a result of the above, due to the difference in the friction coefficient of the road surface on which each wheel is located, the phase of the anti-skid control pattern that repeats depressurization and pressurization is shifted between the left and right wheels, and the yawing (turning) moment that tries to turn the vehicle is generated. Even if the yawing moment occurs, the rear wheels can be steered in a direction to cancel the yawing moment, thereby maintaining the running stability of the vehicle.

Example The present invention will be explained with reference to the accompanying drawings.

In FIG. 1, 1 is a brake pedal, and 2 is a master cylinder. By depressing the brake pedal 1, the master cylinder 2 is operated, and from one cross pipe A to the brake device 4a of the right front wheel 4 and the left rear wheel 5. Hydraulic pressure is supplied to the wheel cylinder of the brake device 5a, and at the same time, hydraulic pressure is supplied from the other cross pipe B to the wheel cylinders of the brake device 3a of the left front wheel 3 and the brake device 6a of the right rear wheel 6, so that the brakes are applied. It has become.

Both of the above-mentioned cross pipes A and B are interposed with actuators 7 that control the braking fluid pressure for each piping system, and the actuators 7 are connected to the front wheels 3 and 4 when the brake pedal 1 is depressed. It is controlled by the pressure increase and decrease signals of the anti-skid control circuit 8 which generates pressure increase and decrease signals of the hydraulic pressure based on the speed sensors 3b and 4b and the wheel speed signals of the rear wheels 5.6 and the wheel speed sensors 5b and 6b. It has become so.

The actuator 7 is installed in the hydraulic piping from the master cylinder 2 to the brake device of each wheel for each piping system, and is closed by a hold signal from the control circuit 8, blocking the hydraulic passage and blocking the brake device of each wheel. the first control valves 9a, 9b that maintain the brake fluid pressure within the first control valve 9a;

The first control valve 9 branches from the hydraulic piping downstream from 9b.
a, a second control valve 10 which is interposed in the bypass piping leading to the upstream side of 9b and is opened by a pressure reduction signal from the control circuit 8;
a, 10b, the second control valves 10a, 10 interposed in the bypass piping downstream of the second control valves 10a, 10b;
It is comprised of electromagnetic pumps lla and llb that operate when the brake valve 11b is opened to pump out the pressure fluid in the brake equipment of each wheel and send it to the upstream side of the first control valves 9a and 9b7.

12a and 12b are proportioning valves interposed in the piping to the rear wheel brake device of both the above-mentioned cross piping A and B, and the proportioning valve 12a,
12b, when the brake pedal is depressed, the brake fluid pressure on the rear wheels is controlled to increase at a lower rate than a certain point compared to the brake fluid pressure on the front wheels, so that when the front wheels are locked, the rear wheels are not yet locked. configured to be in a state,
This is designed to prevent irregular turning (hip swing phenomenon) due to rear wheel locking during braking.

13 is a steering handle, and 14 is a conventionally known front wheel steering device such as a rack and pinion 2. By rotating the steering handle 13, front wheel steering angle information 4 is activated to steer the front wheels 3 and 4. It looks like this.

15 is a rear wheel steering M control circuit, and the rear wheel steering control circuit 1
5 is input with front wheel steering angle information, vehicle speed information, brake fluid pressure information during braking, and yawing moment information of the anti-skid control circuit 8, which are used in the case of a normal rear wheel steering system.Based on these pieces of information, The rear wheel steering control circuit 15 determines the direction and amount in which the left and right rear wheels 5 and 6 should be steered, and outputs an output signal corresponding thereto.

The rear wheel steering actuator has an output generated from the rear wheel steering control circuit 15 to a left rear wheel steering hydraulic cylinder 16L, a right rear wheel steering hydraulic cylinder 16R, and the left and right rear wheel steering hydraulic cylinders 16L and 16R. Pressure reducing valves 18L and 18R so that hydraulic pressure can be supplied independently to the left and right sides depending on the signal.

The left and right rear wheel steering hydraulic pressure controller 17 includes pressurizing valves 19L, 19R, an accumulator 20, and a pressure reducing pump 21, and the left and right rear wheel steering hydraulic cylinders 16
L and 16R are configured to operate independently on the left and right sides in response to output signals separately issued from the rear wheel steering control circuit 15, respectively, so as to steer the left and right rear wheels 5 and 6 separately.

As for the above-mentioned rear wheel steering actuator, the illustrated embodiment shows an example of a hydraulic actuator using a hydraulic cylinder device, but in other cases, an electric motor is used as the drive source and the rotation of the electric motor is decelerated by a reduction gear mechanism. Any actuator can be used, such as an electric type that converts the movement into axial movement of the rack shaft and steers the rear wheels by the axial movement of the rack shaft, or a pneumatic type that uses air pressure as the drive source. It is possible.

In the above configuration, the rear wheel steering control m circuit 15 performs rear wheel steering angle control as described below based on yawing moment information from the anti-skid control circuit 8.

That is, as shown in FIG. 2, the anti-skid control circuit 8 operates as follows: when the brake pedal 1 is depressed, the master cylinder 2 is actuated, and hydraulic pressure is supplied from the master cylinder 2 to the wheel cylinders of each wheel, thereby changing the wheel speed relative to the vehicle body speed Vv. During braking with a lower Vw, the wheel speed Vwa of the lower one of the wheels 4 and 5 belonging to the same hydraulic piping system, for example, the cross piping A system
When the value has decreased to a certain value, the normally open first control valve 9a provided in the cross piping A system is closed, and the air flow from the master cylinder 2 to the right front wheel 4. The hydraulic pressure passages leading to the respective brake devices 4a and 5a of the left rear wheel 5 are shut off, the second control valve 10a is opened, and the electromagnetic pump lla is operated to control the brake devices 4a and 5a.
When the hydraulic pressure inside is reduced to reduce the braking force, and when the degree of decrease in the wheel speed Vwa due to the road reaction force decreases and starts to increase, the second control valve 10a is closed, and the road reaction force causes the wheel speed Vwa to decrease. When the speed Vwa has recovered to a point close to the vehicle body speed Vv, the first control valve 9a is intermittently opened and closed depending on the state of recovery of the wheel speed Vwa, and the brake devices 4a, 5 are activated.
A brake fluid pressure control command is issued to increase the brake fluid pressure supplied to the brake fluid pressure in stages, generate braking force by the gradual increase in the brake fluid pressure, and obtain accurate vehicle deceleration with such a control pattern. The control mode of the anti-skid control circuit 8 as described above is conventionally known.

In the known control mode of the anti-skid control circuit 8 as described above, the amount of reduction in wheel speed during braking differs for each wheel depending on road surface conditions, driving conditions, etc. The manner in which the lower wheel speed Vwb of 6 is reduced is the wheel speed V of the cross pipe A.
If it is gentle compared to wa, the first control valve 9b and the second control valve tab belonging to the cross piping B system as shown in FIG.
The timing of opening and closing is the first control valve 9a belonging to the cross piping A system.

The deviation is large compared to the second control valve 10a, and as a result, the wheel speed Vwb and brake fluid pressure Pb of the cross piping B system change as shown in FIG.
This results in a pattern different from that of the variation of the brake fluid pressure Pa.

As mentioned above, the timing of the pressure reduction from the brake device is shifted between the two loss piping systems A and B, and as shown in FIG. Until the second control valve lOb of the piping B system is opened, the brake fluid pressure Pa decreases and the brake fluid pressure pb increases as shown in FIG. A larger braking force is applied than the wheels 4 and 5 belonging to the pipe A system, but the load distribution between the front and rear wheels is larger on the front wheel side, so the moment in the counterclockwise direction due to the braking force is as shown by the solid line in Figure 3)
Mb is generated. In response to the moment Mb caused by the braking force, the rear wheel steering control circuit 15 intermittently opens and closes the pressure reducing valve 18L and the pressurizing valve 19R depending on the magnitude of the difference between the braking fluid pressure pb and the braking fluid pressure Pa. The rear wheels 5 and 6 are rotated counterclockwise to generate a clockwise moment Ms as shown by the dotted line in FIG. 3 to maintain the stability of the vehicle body.

Next, when the second control valve tab of the cross piping B system is opened, the brake fluid pressure pb of the cross piping B starts to decrease, but the rate of decrease is smaller than the rate of decrease of the brake fluid pressure Pa of the cross piping A system. Therefore, the difference between the brake fluid pressure pb and the brake fluid pressure Pa follows a slight decreasing trend, and the magnitude of the difference between the brake fluid pressures Pb and Pa increases. In response to a slight decreasing trend in moment (Mb) due to the counterclockwise braking force that was occurring proportionally, the rear wheel steering control circuit 15 issues a signal to intermittently open and close the pressure reducing valve 18R2 and the pressurizing valve 19L. Then, the rear wheels 5 and 6, which had been rotated counterclockwise, are rotated clockwise to reduce the moment (Ms) caused by rear wheel steering, thereby maintaining the running stability of the vehicle.

Next, the wheel speed Vwa of the cross piping A system reaches its lowest value, and the second control valve 10a closes.
When a becomes constant, the difference between the brake fluid pressure Pb of the cross piping B system and the brake fluid pressure Pa of the cross piping A system decreases greatly, and the difference occurs in proportion to the magnitude of the difference between the brake fluid pressures Pb and Pa. In response to the large decreasing tendency of the moment Mb due to the counterclockwise braking force, the rear wheel steering control circuit 15 sends a signal to increase the opening operation time of the intermittent opening and closing operations of the pressure reducing valve 18R and the pressurizing valve 19L. The rotation amount of the rear wheels 5 and 6 in the clockwise direction is increased to reduce the moment (Ms) caused by rear wheel steering, thereby maintaining the running stability of the balancing vehicle.

Next, the wheel speed Vwb of the cross piping B system becomes the lowest, and the second control valve 10b closes, and the braking hydraulic pressure pb of the cross piping B system
When becomes constant, the braking fluid pressure Pa between both loss piping A and B systems
, Pb becomes constant and the rear wheel steering control circuit 15 does not perform any control, but in this state, the wheel speed Vwa of the cross piping A system recovers to near the vehicle body speed Vv, and the first control valve 9a starts intermittent opening/closing operation. Continue until.

When the first control valve 9a starts opening/closing, the brake fluid pressure Pa of the cross piping A system increases stepwise. Wheel 4 belonging to cross piping A system increasing in stages
, 5 exerts a larger braking force than the wheels 3 and 6 belonging to the cross piping B system, generating a clockwise braking force moment, and in order to offset the braking force moment, the rear wheel steering operation circuit 15 uses reduced pressure pulp The 18R9 pressurizing valve 19L is intermittently opened and closed to rotate the rear wheel 5.6 in the clockwise direction, generate a counterclockwise moment in the vehicle body, and ensure the stability of the vehicle.

B, each first control valve 9a, 9b, each second control valve 10a, 1
The rear wheel steering control circuit 15 operates the rear wheel 5 according to the opening/closing operation of the rear wheel 0b.
, 6 to repeat the same operation.

In the above embodiment, each cross pipe A is used to determine the magnitude of the braking fluid pressure between the cross pipes A and B.

Although the timing of opening and closing of each first control valve 9a, 9b and each second control valve 10a, 10b belonging to system B is used, the braking fluid pressure Pa, Pb of each cross pipe A, H is detected, and the braking fluid is Of course, the difference between the pressures Pa and Pb may also be used.

In addition to the cross piping system, only the front wheel side has left and right piping,
The rear wheel side can be used for a plurality of piping systems, such as a three-system piping system in which left and right piping is common, or a four-system piping system in which all four wheels are independently piped.

In the diagram shown in FIG. 3 showing the variation of the rear wheel steering angle, the counterclockwise direction is taken as positive.

Effects of the Invention As described above, in the present invention, in an automobile equipped with an anti-skid control device, a rear wheel steering actuator for operating the rear wheels is provided, and the rear wheel steering control circuit determines the direction in which the rear wheels are to be steered and the direction in which the rear wheels are to be steered. The rear wheel steering control circuit is configured to determine the angle and issue an output signal to a rear wheel steering actuator to operate the rear wheels, and the rear wheel steering control circuit generates a signal that detects a turning moment based on a difference in fluid pressure fluctuation when anti-skid is activated. The system is configured to emit an output signal to steer the rear wheels in a direction that cancels out the turning moment, thereby repeatedly depressurizing and pressurizing depending on the difference in the coefficient of friction of the road surface on which each wheel is located or the driving conditions such as when turning. Even if the phase of the anti-skid control pattern is shifted between the left and right wheels and a turning moment is generated to cause the vehicle to turn, the rear wheels are steered in a direction to cancel the turning moment to maintain the running stability of the vehicle. This makes it possible to improve safety, and together with the simple configuration, it can bring about great practical effects.

[Brief explanation of the drawing]

The attached drawings show an embodiment of the present invention, in which Fig. 1 is an explanatory diagram of a brake hydraulic system and a control system, Fig. 2 is a time chart showing a control mode of the invention, and Fig. 3 is a diagram showing an example of a braking hydraulic system and a control system. FIG. 3 is an explanatory diagram showing a relationship between a moment and a rear wheel turning angle.

Claims (1)

[Claims] During braking, when hydraulic pressure is supplied from the master cylinder to the brake equipment of each wheel by pressing the brake pedal, the hydraulic pressure is released as the wheel speed decreases relative to the vehicle body speed, reducing the braking force. In automobiles equipped with an anti-skid control device that uses a control system that repeats a control pattern in which hydraulic pressure is supplied and pressurized again after the wheel speed has recovered, a rear wheel steering actuator is installed to operate the rear wheels to steer the rear wheels. The angle control circuit determines the direction and steering angle in which the rear wheels should be steered, issues an output signal to the rear wheel steering actuator, and operates the rear wheels to steer the rear wheels. An anti-skid device characterized in that the anti-skid device is configured to generate an output signal to steer the rear wheels in a direction to cancel the turning moment based on a signal that detects the turning moment based on the difference in hydraulic pressure fluctuation between the left and right wheels during operation. Rear wheel steering device for vehicles with attached vehicles.