JP2002114139A - Hydraulic brake system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic brake system that can prevent generation of large noise and vibration of an antiskid means without causing cost increase due to structural modification to a solenoid valve and addition of a damping member. SOLUTION: At the start of antiskid control, a control means 91 controls an assist means 71 to reduce the output hydraulic pressure of a master cylinder 1 down to a given hydraulic pressure lower than that before the start of antiskid control and higher than the internal hydraulic pressure of a wheel cylinder in the antiskid control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic brake device for a vehicle.

[0002]

2. Description of the Related Art When anti-skid control is performed in a hydraulic brake device, the hydraulic pressure in a wheel cylinder is controlled by repeatedly opening and closing an electromagnetic valve provided in the anti-skid means.

[0003]

However, due to oil hammer due to repeated opening and closing of the solenoid valve, loud noises and vibrations are generated in the anti-skid means. Was transmitted to give the driver discomfort.

In particular, when the anti-skid control is performed while the vehicle is traveling on a low μ road, the hydraulic pressure in the wheel cylinder is considerably smaller than the output hydraulic pressure of the brake master cylinder, and the output hydraulic pressure of the brake master cylinder is reduced. In anti-skid control in which the pressure difference between the pressure and the fluid pressure in the wheel cylinder is intermittently opened and closed by opening and closing an electromagnetic valve, a large differential pressure increases noise and vibration.

The present invention has been made in view of the above circumstances, and prevents generation of noise and vibration in the anti-skid means without causing a cost increase due to a change in the structure of the solenoid valve or the addition of a vibration damping member. It is an object of the present invention to provide a hydraulic brake device capable of performing the following.

[0006]

Means for Solving the Problems To solve the above technical problem, as set forth in claim 1, the pedaling force applied to a brake pedal is converted into a hydraulic pressure of brake fluid and transmitted to a wheel cylinder of a wheel brake. A brake master cylinder, an assisting means for applying an assisting force independent of a treading force applied to the brake pedal to the brake master cylinder, and an output hydraulic pressure of the brake master cylinder to prevent skid of the wheel brake. Anti-skid means, a hydraulic brake device comprising a control means for controlling the assisting means and the anti-skid means,
When the anti-skid control is started, the output hydraulic pressure of the master cylinder is smaller than the hydraulic pressure before the anti-skid control is started and is higher than the hydraulic pressure in the wheel cylinder where the anti-skid control is being performed. The hydraulic brake device is characterized in that the control means controls the assisting means so as to reduce the pressure to the hydraulic pressure.

According to the present invention, when the anti-skid control is started, the output hydraulic pressure of the master cylinder is smaller than the hydraulic pressure before the anti-skid control is started, and the anti-skid control is executed. Control so as to decrease to a predetermined hydraulic pressure larger than the hydraulic pressure in the wheel cylinder, the difference between the output hydraulic pressure of the brake master cylinder and the hydraulic pressure in the wheel cylinder is small, and the noise generated in the anti-skid means is reduced. Vibration can be minimized.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a hydraulic circuit diagram of a hydraulic brake device according to an embodiment of the present invention. FIG. 2 is a time chart showing changes in the output hydraulic pressure of the brake master cylinder and the hydraulic pressure in the wheel cylinder of the hydraulic brake device according to the embodiment of the present invention.

In FIG. 1, a tandem-type brake master cylinder 1 has an input rod 2.
Is connected to the brake pedal 4. Input rod 2
Transmits the pedaling force applied to the brake pedal 4 to the first piston 11. Further, the brake master cylinder 1 integrally has a reservoir 7 in which brake fluid is stored at an upper portion thereof.

The master cylinder 1 has a first piston 11 and a second piston 12 therein, and the first piston 11 and the second piston 12 allow the first pressure chamber 1 to be opened.
3, a second pressure chamber 14 and a third pressure chamber 17 are defined. That is, the first pressure chamber 13 is formed between the first piston 11 and the second piston 12, the second pressure chamber 14 is formed between the bottom of the inner hole of the body 3 and the second piston 12, and the first pressure chamber 13 is formed. A third pressure 17 chamber is formed between the piston 11 and the front wall of the body 3.

In the first pressure chamber 13, a first spring device 15 is provided between the first piston 11 and the second piston 12. Further, in the second pressure chamber 14, between the second piston 12 and the bottom of the inner hole of the body 3,
A second spring device 16 is provided.

The master cylinder 1 has a first port 21 and a third port 23 communicating with the first pressure chamber 13, and has a second port 22 and a fourth port 24 communicating with the second pressure chamber 14. Further, the master cylinder 1 has a fifth port 25 communicating with the third pressure chamber 17.

The first port 21 and the second port 22 are connected to the reservoir 7 via a passage 31 and a passage 32, respectively. The brake fluid stored in the reservoir 7 is
It is introduced into the first pressure chamber 13 via the passage 31 and the first port 21 and is introduced into the second pressure chamber 14 via the passage 32 and the second port 22.

A third port 23 communicating with the first pressure chamber 13
And a fourth port 24 communicating with the second pressure chamber 14 is connected to a solenoid valve device 81 (anti-skid means) via a passage 33 and a passage 34, respectively. , 43, 44, the wheel cylinders 51, 52, 53, 54 disposed on each wheel.
It is connected to the.

Fifth port 25 communicating with third pressure chamber 17
Is connected to the solenoid valve 72 through the passage 35, and the solenoid valve 7
2 is connected to the reservoir 7 via a passage 37.

The first piston 11 is operatively connected to the input rod 2 at the rear (in the rear direction of the vehicle; the same applies hereinafter). In the present embodiment, the first piston 11 and the input rod 2 are formed separately, but may be formed integrally.

When the brake pedal 4 is depressed, a force proportional to the depressing force of the brake pedal 4 acts on the input rod 2. Due to the force acting on the input rod 2, the first piston 11 is pushed forward (toward the front of the vehicle; the same applies hereinafter) to move, and with the movement of the first piston 11, the communication hole ( (Not shown) is closed by a seal cup (not shown) provided in the body 3, and communication between the first pressure chamber 13 and the first port 21 is cut off. When the first piston 11 is further pressed, a hydraulic pressure is generated in the first pressure chamber 13, and the hydraulic pressure is transmitted to the wheel cylinder via the third port 23. The mechanism in which the communication hole of the first piston 11 is closed by a seal cup provided in the body 3 to generate hydraulic pressure in the first pressure chamber 13 is a mechanism widely used in a so-called plunger type brake master cylinder, and is described in detail. Is omitted.

The second piston 12 is pushed forward by the hydraulic pressure generated in the first pressure chamber 13 and the force acting on the input rod 2 transmitted through the first spring device 15 to move. With the movement of the second piston 12, the second
The communication hole (not shown) of the piston 12 is closed by a seal cup (not shown) provided in the body 3,
The communication between the pressure chamber 14 and the second port 22 is cut off. When the second piston 12 is further pressed, a hydraulic pressure is generated in the second pressure chamber 14, and the hydraulic pressure is transmitted to the wheel cylinder via the fourth port 24.

When the brake pedal 4 is returned with the end of the brake operation, the first piston 11 is moved by the hydraulic pressure and the elastic force of the first spring device 15 and the second spring 16.
And the second piston 12 is returned to the original position. As a result, the first port 21 and the second port 22 communicate with the first pressure chamber 13 and the second pressure chamber 14, respectively, and the hydraulic pressure generated in the wheel cylinder is released.

The brake master cylinder 1 has a fifth port 25 communicating with the third pressure chamber 17. Fifth port 2
5 is a reservoir 7 via a first check valve 75 and a pump 73.
It is connected to the. When the pump 73 is driven by the electric motor 74, the brake fluid stored in the reservoir 7 is sucked out and pressurized, and is supplied to the third pressure chamber 17 via the first check valve 75. The first piston 11 is pressed forward by the hydraulic pressure of the brake fluid supplied to the third pressure chamber 17. That is, another assisting force independent of a force proportional to the depression force of the brake pedal 4 is applied to the first piston 11.

The fifth port 25 communicating with the third pressure chamber 17 is connected to the reservoir 7 via a solenoid valve 72,
A second check valve 76 is connected to the solenoid valve 72 in parallel. When the solenoid valve 72 is at the position a, the solenoid valve 72
Serves as a cut valve to prevent the brake fluid in the third pressure chamber 17 from returning to the reservoir 7. When the valve 72 is at the position b, the solenoid valve 72 serves as a communication passage and serves as the third pressure chamber 17.
Can be returned to the reservoir 2. Also,
Since the solenoid valve 72 is a linear valve, it functions as a pressure regulating valve, and can communicate the third pressure chamber 17 with the reservoir 7 while gradually reducing the fluid pressure in the third pressure chamber 17.

The above-described solenoid valve 72, pump 73,
The electric motor 74, the first check valve 75 and the second check valve 76 constitute the assisting means 71.

The control of the solenoid valve 72 and the electric motor 74 is performed by a controller 91 (control means). The controller 91 includes a pedal sensor 101 for detecting a pedal stroke or a pedaling force, a wheel speed sensor 103 for detecting a wheel speed, and a vehicle speed sensor 10 for detecting a vehicle speed.
4 is input. The controller 91
Based on the detection signals from the pedal sensor 101, the wheel speed sensor 103, and the vehicle speed sensor 104, it is determined that the brake pedal 4 has been depressed, and the electric motor 74 is driven and the electromagnetic valve 72 is moved to the a position or the b position. The switching control is performed.

The controller 91 has a hydraulic pressure sensor 102 for detecting the output hydraulic pressure of the brake master cylinder 1.
Is input. The controller 91 calculates the hydraulic pressure in the passage 33 based on the detection signal from the hydraulic pressure sensor 102, and controls the rotation speed of the electric motor 74 and the solenoid valve 72 so that the hydraulic pressure in the passage 33 becomes a predetermined value. The assisting force is controlled by adjusting the opening degree and controlling the hydraulic pressure in the third pressure chamber 17.

Further, the controller 91 includes the wheels 6
Wheel speed sensor 1 disposed at 1, 62, 63, 64
A wheel speed signal of each wheel is input on the basis of the detection signal from 03. From the wheel speed signal of each wheel during brake operation,
If a tendency to lock any of the wheels is detected,
The controller 91 is a solenoid valve device 81 (anti-skid means) corresponding to a wheel cylinder of a wheel that tends to lock.
The anti-skid control to prevent the wheel lock by opening and closing the solenoid valve continuously.

FIG. 2 shows the hydraulic pressure Pw in the wheel cylinder and the output hydraulic pressure Pm of the brake master cylinder during the anti-skid control of the hydraulic brake device according to the present embodiment.
6 is a graph showing a temporal change of the graph.

In FIG. 2, point A represents the time at which the driver started the braking operation, and point B represents the time at which the controller 91 has started anti-skid control when a tendency to lock any one of the wheels has been detected. .

In normal anti-skid control, B
When the anti-skid control is started at the point, the electromagnetic valve device 81 immediately shuts off the communication between the wheel cylinder of the wheel that tends to lock and the brake master cylinder 1. However, the driver is
, The output hydraulic pressure Pm of the brake master cylinder 1 continues to rise to a predetermined hydraulic pressure Pm1 as shown by a two-dot chain line in FIG. Pm1 is the total hydraulic pressure of the hydraulic pressure generated by the force proportional to the depression force of the brake pedal 4 and the hydraulic pressure generated by the assisting means 71.

Output hydraulic pressure Pm of brake master cylinder 1
Is continuously rising after the point B, the solenoid valve device 81
The solenoid valve corresponding to the wheel cylinder of the wheel having a tendency to lock is continuously opened and closed to lower the hydraulic pressure Pw in the wheel cylinder. Therefore, since the solenoid valve of the solenoid valve device 81 is opened and closed under a pressure difference of Pm1−Pwr at the minimum, a loud noise or vibration is generated in the solenoid valve device 81 by the oil hammer.

On the other hand, in this embodiment, when the tendency of locking any one of the wheels is detected and the controller 91 starts the anti-skid control, at the same time,
The hydraulic pressure generated by the brake master cylinder 1 is reduced to a predetermined hydraulic pressure.
From Pm1 to Pm2.

As a result, the output hydraulic pressure Pm of the brake master cylinder 1 reaches Pm2 after the point B. Therefore, the differential pressure Pm1-Pw during normal anti-skid control
The solenoid valve of the solenoid valve device 81 is opened and closed under a differential pressure of Pm2−Pwr that is considerably smaller than r.
The generation of noise and vibration due to the oil hammer in 1 is minimized.

[0032]

According to the present invention, it is possible to prevent the generation of loud noise and vibration of the anti-skid means without increasing the cost due to the change in the structure of the solenoid valve or the addition of a vibration damping member.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of a hydraulic brake device according to an embodiment of the present invention.

FIG. 2 is a graph showing a temporal change of a hydraulic pressure Pw in a wheel cylinder and an output hydraulic pressure Pm of a brake master cylinder during anti-skid control of the hydraulic brake device according to the embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 brake master cylinder 4 brake pedal 51, 52, 53, 54 wheel cylinder 71 assisting means 81 anti-skid means 91 control means

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3D046 BB07 BB28 HH02 HH16 HH22 HH36 LL02 LL05 LL11 LL23 LL37 3D048 BB25 BB31 CC09 HH15 HH26 HH31 HH53 HH66 RR01 RR06 RR11 RR25 RR35

Claims (1)

[Claims] 1. A brake master cylinder for converting a pedaling force applied to a brake pedal into a hydraulic pressure of brake fluid and transmitting the same to a wheel cylinder of a wheel brake, and an assisting force independent of the pedaling force applied to the brake pedal. Assisting means for applying to the brake master cylinder, anti-skid means for adjusting the output hydraulic pressure of the brake master cylinder to prevent skid of the wheel brake, and control means for controlling the assisting means and the anti-skid means. In the hydraulic brake device provided, when the anti-skid control is started, the wheel in which the output hydraulic pressure of the master cylinder is smaller than the hydraulic pressure before the anti-skid control is started and the anti-skid control is executed In order to reduce the pressure to a predetermined pressure greater than the hydraulic pressure in the cylinder, the control means A hydraulic brake device for controlling the assisting means.