JP2776904B2 - Vehicle slip control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vehicle slip control device, and more particularly to a vehicle slip control device that performs slip control during vehicle acceleration.

2. Description of the Related Art Conventionally, a slip control device for a vehicle that performs such slip control during acceleration is described in, for example, pages 7-104 of the Toyota Crown New Model Manual (issued in September 1987). What was done is known.

In this device, an M / C cut solenoid valve and a check valve for cutting the brake hydraulic pressure of the master cylinder are provided in parallel in a brake fluid passage connecting the brake master cylinder and the wheel cylinder, and a slave cylinder is provided downstream of these valves. Further, an accumulator for accumulating brake fluid in the reservoir by a pump is provided, and control oil pressure from the accumulator is applied to a drive pressure chamber of a slave cylinder via a pressure-intensifying solenoid valve, and the drive pressure chamber is It is connected to the reservoir via a pressure reducing solenoid valve. During normal traveling, the M / C cut solenoid valve and the pressure reducing solenoid valve are opened, the pressure increasing solenoid valve is closed, and the control oil pressure from the accumulator is shut off.

Therefore, when a drive slip occurs, the M / C cut solenoid valve is closed, the brake operating hydraulic circuit between the master cylinder and the wheel cylinder is shut off, and at the same time, the pressure increasing solenoid valve opens and the pressure reducing solenoid valve opens. By closing, the control oil pressure from the accumulator is introduced into the drive pressure chamber of the slave cylinder.
Therefore, the hydraulic pressure is generated by the movement of the piston of the slave cylinder, and the hydraulic pressure of the wheel cylinder is increased. Further, at the time of pressure reduction control, the pressure reduction solenoid valve is opened, and the pressure increase solenoid valve is closed, so that the control hydraulic pressure of the drive pressure chamber is released to the reservoir, and the hydraulic pressure of the slave cylinder is reduced.

[Problems to be Solved by the Invention] However, in such a conventional vehicle slip control device, an accumulator serving as a pressure source for slip control during acceleration, a solenoid valve for increasing and decreasing pressure, and a pressure It has a slave cylinder for generation and an M / C cut solenoid valve that cuts the hydraulic pressure from the master cylinder, and the wheel cylinder is pressurized by the slave cylinder during acceleration slip, so that the wheel cylinder pressure rises However, there is a problem that the slip control is not reliably performed.

In addition, there is a problem that the device becomes complicated due to the provision of the slave cylinder.

An object of the present invention is to provide a vehicle slip control device capable of solving the problems of the conventional device and reliably performing the slip control while avoiding complication of the device.

Means for Solving the Problems In order to achieve the above object, the present invention provides a master cylinder that generates a hydraulic pressure in accordance with a brake operation, and a pressure accumulator that accumulates a pressure liquid supplied by a supply pressure source. A wheel cylinder connected to the master cylinder and the pressure accumulator by piping, a slip detection means for detecting wheel slip, and a connection between the master cylinder and the wheel cylinder when the slip detection means detects an acceleration slip. Pressure source switching means for switching the device to be connected to the wheel cylinder, and at the time of pressure reduction control of the acceleration slip control, a throttle is formed upstream of the fluid pressure source switching means of the pipe connecting the master cylinder and the wheel cylinder, And a pressure reducing means for releasing the hydraulic pressure of the wheel cylinder.

[Operation] According to the present invention, during an acceleration slip, the pressure accumulator is connected to the wheel cylinder by the switching operation of the pressure reduction source switching means, and the wheel cylinder pressurization during acceleration is directly driven by the pressure from the pressure accumulator. This is performed by being supplied to the wheel cylinder of the wheel.

Then, during the pressure reduction control of the wheel cylinder, the hydraulic pressure of the wheel cylinder is released via the throttle formed by the pressure reduction adjusting means on the upstream side of the hydraulic pressure source switching means. Therefore,
The wheel cylinder pressure quickly rises, and reliable slip control is performed.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a configuration block diagram showing an embodiment of the present invention.

In the figure, reference numeral A denotes a master cylinder provided with a reservoir B, which generates a hydraulic pressure in response to depression of a brake pedal C. D is a drive wheel wheel cylinder connected to the master cylinder A by piping. E is a slip detecting means for detecting wheel slip, and F is a pressure accumulator for storing pressure fluid.

G is a hydraulic pressure source switching means for disconnecting the connection between the master cylinder A and the wheel cylinder D and switching the accumulator F to be connected to the wheel cylinder D when the slip detection means E detects an acceleration slip. It is a supply pressure source for supplying pressurized liquid to the vessel F. J is a pressure reducing adjusting means for forming a throttle upstream of the hydraulic pressure source switching means G in the pipe connecting the master cylinder A and the wheel cylinder D to release the hydraulic pressure of the wheel cylinder D during the pressure reducing control of the acceleration slip control. It is.

Next, FIG. 2 shows a schematic configuration diagram according to an embodiment of the present invention.

In the figure, reference numeral 10 denotes a master cylinder having first and second hydraulic pressure generating chambers, which includes a reservoir 11 for storing brake fluid, and generates a hydraulic pressure in accordance with the amount of depression of a brake pedal 12.

20 is a wheel cylinder provided on each wheel 21;
Below, the right front wheel 21FR wheel cylinder is 20FR, the left front wheel 21FL
Wheel cylinder of 20FL, right rear wheel 21RR and left rear wheel 21R
L wheel cylinders are referred to as 20RR and 20RL, respectively.

In the present embodiment, the rear wheels 21RR and 21RL are driving wheels,
The front wheels 21FR and 21FL are longitudinally driven wheels, and the front and rear wheels are provided with wheel speed sensors 22A and 22B for detecting the rotation speed of the wheels, respectively.

The first hydraulic pressure generating chamber of the master cylinder 10 is connected to the left and right rear wheel cylinders 20RL and 20RR via a first passage 31 and a first branch passage 31A branched therefrom. The second hydraulic pressure generating chamber of the master cylinder 10 is connected to the left and right front wheel cylinders 20FL and 20FL via a second passage 32 and a second branch passage 32A branched therefrom.
Connected to FR.

Further, the first passage 31 is provided with a first electromagnetic switching valve 51 as a hydraulic pressure source switching means. In the common passage 35 connecting the reservoir 11 of the master cylinder 10 and the downstream side of the first electromagnetic switching valve 51, a second electromagnetic switching valve 52 is also provided as a hydraulic pressure source switching means.

The first electromagnetic switching valve 51 is a normally open 2-port 2-position electromagnetic valve, and the second electromagnetic switching valve 52 is a normally-closed 2-port 2-position electromagnetic valve, and is controlled by a signal from a controller 60 described later.

In addition, each electromagnetic switching valve is integrated,
Of course, it may be configured as a position solenoid valve.

Next, 70 is a pump driven by a motor 71, for example, as a plunger-type supply pressure source, is provided in the supply passage 35, and the motor 71 is also controlled by a signal from the controller 60.

Reference numeral 80 denotes an accumulator as a pressure source, which is connected to the above-described second electromagnetic switching valve 52 via the check valve 72,
When the electromagnetic switching valve 51 operates to disconnect the connection between the master cylinder 10 and the rear wheel cylinders 20RL and 20RR, the communication is made with the rear wheel cylinders 20RL and 20RR. The accumulator 80 further includes a pump 70 driven by a motor 71.
Is connected via a differential pressure actuated valve 81 to the common passage 35 on the discharge side. The discharge pressure of the pump 70 and the pressure of the accumulator 80 are input to the differential pressure operating valve 81 as pilot pressures.

Further, the discharge side and the suction side of the pump 70 are connected via a relief valve 83.

Reference numeral 84 denotes a stroke switch, which performs a switch operation according to a piston stroke when the accumulation of pressure in the accumulator 80 is completed. In the illustrated embodiment, a switch contact is provided in the container of the accumulator 80, and the switch contact is turned on when the piston strokes due to the accumulation of pressure. If the end of the pressure accumulation is detected by the stroke of the piston in this way, a pressure detector is not required separately from the pressure accumulator, and the cost can be reduced. Further, it is preferable because piping to the pressure detector and the like are not required, and leakage measures can be minimized.

Reference numeral 85 denotes a pressure-reducing adjusting valve disposed upstream of the first electromagnetic switching valve 51 in the first passage 31, which urges the cylinder 85A, the piston 85B sliding in the cylinder 85A, and the piston 85B downward. Spring 85C. Cylinder 85A
A passage 85D formed on the upper surface of the cylinder 85A is communicated with the first hydraulic pressure generation chamber of the master cylinder 10, and a passage 85E formed on the side surface of the cylinder 85A is communicated with the first electromagnetic switching valve 51.

The passage 85F formed on the lower surface of the cylinder 85A is communicated with the downstream side of the first electromagnetic switching valve 51, and the passages 85D and 85E
Are separated from the piston 85B and the oil seal 85G. Passage 58D and passage 85E have piston 85B with spring 85C
When the piston 85B is pushed back downward, it communicates completely, but the pressure in the passage 85F rises and the piston 85B
When pushed upward against 85C, it is communicated via a variable throttle (orifice) 85K formed by the shoulder of piston 85B and the inner wall surface of cylinder 85A.

The controller 60 is constituted by a microcomputer, and as shown in FIG. 3, the wheel speed sensors 22A and 22A.
B, and a CPU 61 for inputting and calculating data detected by the stroke switch 84 in accordance with a control program, and performing processing for controlling the driving of the first and second electromagnetic switching valves 51 and 52 and the motor 71; ROM 62 in which programs and reference data are stored, RAM 63 in which data necessary for each sensor and arithmetic control are temporarily stored, a waveform shaping circuit and a multiplexer for selectively outputting an output signal of each sensor to the CPU 61, etc. The input unit 64 with
An output unit 65 having a drive circuit driven in accordance with a control signal from the CPU 61 and a bus line 66 connecting each unit are provided.

 Next, the operation of the present embodiment having the above configuration will be described.

(1) At the time of normal brake operation At the time of normal brake operation in which the slip control is not performed during acceleration, the first electromagnetic switching valve 51 is opened, and the second electromagnetic switching valve 52 is opened.
Is in the closed state. Then, the master cylinder 10 and the wheel cylinders 22RR and 20RL of the rear wheels which are the driving wheels, and the wheel cylinders 20FL and 20FR of the front wheels which are the vertical driving wheels.
And the accumulator 80 is disconnected and in an independent state.

Accordingly, when the brake pedal 12 is depressed, the hydraulic pressure in the first hydraulic pressure generating chamber is increased via the first passage 31 including the passages 85D and 85E of the pressure reducing valve 85 and the first branch passage 31A. The hydraulic pressure of the second hydraulic pressure generating chamber is supplied to the cylinders 20RL and 20RR via the second passage 32 and the second branch passage 32A, respectively.
To each other while maintaining their independence.

At this time, the hydraulic pressure in the first passage 31 is prevented from flowing to other pipes by the second electromagnetic switching valve 52, so that the hydraulic rigidity is kept high without causing pressure relief.

(2) Slip Control During Acceleration Next, an example of a control procedure for slip control during acceleration will be described with reference to the flowchart of FIG.

The control procedure shown in this flowchart is started at regular intervals (for example, 5 ms) by an operation system (not shown).

When the control is started, first, in step S1, it is determined whether or not the stroke switch 84 is on. If it is not on, that is, if the pressure of the accumulator 80 has not reached the predetermined value, the process proceeds to step S2, where the pump is
Activate 70. At this time, the discharge pressure of the pump 70 and the accumulator
If the differential pressure from the pressure of 80 is equal to or more than a predetermined value, the differential pressure actuated valve 81
The pressure in the pressure accumulator 80 is accumulated. If the stroke switch 84 is turned on in step S1, the pressure accumulator 80 has been stored at a predetermined pressure.
Stop the operation of. After step S2 or step S3, the process proceeds to step S11. In step S11, the right front wheel rotation speed Vf1 and the difference front wheel rotation speed Vf2 are read as output values of the wheel speed sensor 22A, and in step S12, the front wheel average rotation speed Vf is calculated. Is calculated as

Next, in step S13, the rear wheel average rotation speed Vr is read as the output value of the wheel speed sensor 22B, and in step S14, the slip ratio S is calculated from the front wheel average rotation speed Vf and the rear wheel average rotation speed Vr. Is calculated as

In step S15, it is determined whether or not a braking operation is being performed based on an output signal of a pedal switch (not shown). If it is operating, the process proceeds to step S31, the flag is set to 0, and the first and second electromagnetic switching valves 51 and 5 are set in step S32.
Turn 2 off. The master cylinder 10 and each wheel cylinder 20 are brought into communication.

On the other hand, if the brake operation is not being performed in step S15, the process proceeds to step S16, and it is determined whether the slip ratio S exceeds a predetermined slip ratio control upper limit value Sa. If S> Sa, that is, if a large acceleration slip has occurred, the flag is set to 1 in step S17,
In step S18, the normally opened first electromagnetic switching valve 51 and the normally closed second electromagnetic switching valve 52 are turned on, and the pressure accumulator 80 and the rear wheel wheel cylinders 20RL and 20RR as driving wheels are connected via the check valve 72. And increase the wheel cylinder pressure of the rear wheels. Further, the pump 70 sucks the brake fluid from the reservoir 11, and receives the first fluid through the second electromagnetic switching valve 52 in the ON state.
It is discharged into the passage 31 to increase the wheel cylinder pressure of the rear wheels. The first passage 31 and, consequently, the rear wheel cylinder 20
When the pressure of RL and 20RR increases and the pressure difference between the pressure accumulator 80 and the pressure accumulator 80 exceeds a predetermined value, the pressure accumulator 80 is accumulated via the differential pressure actuating valve 81.

The excess pressure exceeding the allowable storage pressure of the pressure accumulator 80 is returned to the supply passage 35 via the relief valve 83, and is sucked into the pump 70 or returned to the reservoir 11 of the master cylinder 10.

Further, at this time, as the pressures of the wheel cylinders 20RL and 20RR increase, pressure is applied to the pressure reducing adjustment valve 85 below the piston 85B via the passage 85F, and the piston 85B moves upward.

On the other hand, if S <Sa in step S16, that is, if the slip ratio S during acceleration does not exceed the control upper limit Sa,
Proceeding to step S41, it is determined whether the flag has been set to "1".

If the flag is set to 1, the process proceeds to step S42, where it is determined whether the slip ratio S exceeds the slip ratio control lower limit Sb.

If S> Sb, the process proceeds to step S43, where the first electromagnetic switching valve 51 is turned on and the second electromagnetic switching valve 52 is turned off. As a result, the pressures of the wheel cylinders 20RL and 20RR are maintained in a predetermined slip ratio range in which the driving force is maximized. If S> Sb is not satisfied in step S42, that is, if the acceleration slip ratio S is sufficiently small, the process proceeds to step S51, where both the first electromagnetic switching valve 51 and the second electromagnetic switching valve 52 are turned off. This allows wheel cylinders 20RL and 20RR
The brake fluid flows out to the master cylinder 10 through the passage 85E of the pressure-reducing regulating valve 85, the throttle formed by the shoulder of the piston 85B and the inner wall surface of the cylinder 85A, and the passage 85D to reduce the pressure.

On the other hand, if the flag is not 1 in step S41, that is, if the previous acceleration slip control has not been performed, the process proceeds to the end and returns to the start again.

Note that, in the above-described embodiment, an example in which the variable throttle is formed by the shoulder of the piston 85B and the inner wall surface of the cylinder 85 as the pressure-reducing valve 85 has been described. The pressure reducing valve 85 as shown may be used.

This is the rear wheel cylinder 20RL and 20RR
When the pressure increases, that is, when the piston 85B moves upward, the seal member 85H provided at the upper end of the piston 85B closes the passage 85D formed on the upper surface of the cylinder 85A, and at this time, the passage 85D is bypassed. Only the small-diameter passage 85J formed in this way communicates as a fixed throttle. The other configuration is the same as that of the previous embodiment, so that the same portions are denoted by the same reference numerals and the description thereof will be omitted.

Further, in this embodiment, an example has been shown in which the hydraulic pressure of the wheel cylinder is controlled by a combination of two solenoid-operated switching valves. Needless to say, the same control can be performed by using the same.

Although the present embodiment has been described with reference to a rear-wheel drive vehicle, even a front-wheel drive vehicle can perform slip control during acceleration by controlling the wheel cylinder hydraulic pressure of the drive wheels.

[Effects of the Invention] As is apparent from the above description, according to the present invention, in a vehicle slip control device using a pressure accumulator that accumulates a pressurized liquid supplied from a supply pressure source, a master device is used for detecting an acceleration slip. Hydraulic pressure source switching means for disconnecting the connection between the cylinder and the wheel cylinder and switching the pressure accumulator to the wheel cylinder, and hydraulic pressure source switching means for connecting the master cylinder and the wheel cylinder during pressure reduction control of acceleration slip control A throttle is formed on the upstream side of the cylinder, and a pressure reduction adjusting means for releasing the hydraulic pressure of the wheel cylinder is provided, so that it is possible to prevent the rise of the wheel cylinder pressure from being delayed at the time of acceleration slip.
A vehicle slip control device capable of performing slip control simply and reliably can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a schematic block diagram showing an embodiment of the present invention, FIG. 3 is a block diagram showing an example of a controller, and FIG. FIG. 5 is a flow chart showing an example of a control procedure according to the embodiment. FIG. 10, A ... master cylinder, 11, B ... reservoir, 20, D ... wheel cylinder, 22 ... wheel speed sensor, 31 ... first passage, 32 ... second passage, 35 ... supply passage, 51: first electromagnetic switching valve (hydraulic pressure source switching means), 52: second electromagnetic switching valve (hydraulic pressure source switching means), 60: controller, 70: pump (pressure supply source), 80, F …… Pressure accumulator, 81 …… Differential pressure operated valve, 84 …… Stroke switch, 85 …… Reduced pressure regulating valve, 85J …… Fixed throttle, 85K …… Variable throttle.

Continued on the front page (72) Inventor Yuji Oishi 1370 Onna, Atsugi-shi, Kanagawa Prefecture Inside Atsugi Automobile Parts Co., Ltd. (72) Eiji Yagi In-house 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Nissan Motor Co., Ltd. (56 References JP-A-57-22948 (JP, A) JP-A-60-183658 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B60T 8/32-8/58

Claims (1)

(57) [Claims] 1. A master cylinder for generating a hydraulic pressure in response to a brake operation, a pressure accumulator for accumulating a pressure fluid supplied by a supply pressure source, and a wheel connected to the master cylinder and the pressure accumulator by pipes, respectively. A cylinder, slip detection means for detecting wheel slip, and disconnection between the master cylinder and the wheel cylinder when the slip detection means detects an acceleration slip, and switching to connect the pressure accumulator to the wheel cylinder. A hydraulic pressure source switching means, and at the time of pressure reduction control of the acceleration slip control, a throttle is formed upstream of the hydraulic pressure source switching means in a pipe connecting the master cylinder and the wheel cylinder, and a hydraulic pressure of the wheel cylinder is reduced. And a pressure-reducing adjusting means for escaping.