JP2003341504A - Master cylinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent delay of braking by preventing a first cup seal member demarcating a first hydraulic chamber and a liquid-tight seal member from moving in an axial direction. <P>SOLUTION: When a first piston is moved frontward, working liquid is supplied to first and second brake systems from first and second hydraulic chambers demarcated by first and second cup seal members, respectively. The liquid tight seal member and the first cup seal member defining a front end of the first hydraulic chamber are energized by an elastic member in a direction to be separated from each other, and are brought into contact with a back face of a second piston guide and a front face of a first piston guide, respectively. Thereby, even if a resin sleeve becomes short due to variation of environment and aging, the first cup seal member and the liquid-tight seal member are held in a predetermined position and not moved. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a master cylinder used in a brake device for automobiles and the like.

[0002]

2. Description of the Related Art Conventionally, a cylinder is formed in a cylinder body, a first piston is slidably fitted to a first piston guide provided with a rear end portion of the cylinder having a small diameter, and the first piston is attached to an intermediate portion. A second piston is slidably fitted to the two-piston guide, first and second pistons are fitted to supply the brake fluid pressure to the first and second brake systems, respectively. The first and second cup seal members partitioning into the hydraulic chamber are brought into contact with the front surfaces of the first and second piston guides, respectively, and the liquid-tight seal member that defines the front end of the first hydraulic chamber is set to the second.
In order to bring the first cup seal member and the liquid-tight seal member into axial alignment with the rear face of the piston guide, a master cylinder in which a resin sleeve in which the first piston fits is interposed between them is specially designed. Kaihei 11-268829
It is described in Japanese Patent Publication No.

[0003]

In the above-mentioned conventional master cylinder, the resin sleeve is excellent in abrasion resistance against sliding of the first piston, but the resin is environmentally friendly,
It shortens in the axial direction due to changes with time, and an axial gap is created between the first cup seal member and the liquid-tight seal member. The axial movement of the first cup seal member or the liquid-tight seal member due to this gap results in consumption of the brake fluid at the start of brake operation, which increases the ineffective stroke of the first piston, which causes a delay in braking.

The present invention has been made in order to solve the above-mentioned conventional inconvenience, and the brake is provided so that the first cup seal member and the liquid-tight seal member for partitioning the first hydraulic chamber do not move in the axial direction. It is to prevent handedness delay.

[0005]

In order to solve the above-mentioned problems, a structural feature of the present invention as set forth in claim 1 is that a cylinder is formed in a cylinder body, and a first end is provided at a rear end portion of the cylinder. The first piston is slidably fitted to the piston guide, the second piston is slidably fitted to the second piston guide provided in the middle part, and the first piston and the second piston are fitted to each other. First and second cup seal members that divide the cylinder into first and second hydraulic pressure chambers that supply brake hydraulic pressure to the first and second brake systems, respectively, are applied to the front surfaces of the first and second piston guides, respectively. A liquid-tight seal member that defines the front end of the first hydraulic chamber and abuts against the back surface of the second piston guide, and the first cup seal member and the liquid-tight seal member have the first and second fluid-tight seal members. Master with resin sleeve that fits one piston In Linda, the liquid-tight sealing member and said liquid elastic member that urges the first cup seal member in a direction away from each other tight seal member and the first
It is arranged at an appropriate place between the cup seal members.

According to a second aspect of the present invention, in the master cylinder according to the first aspect, the elastic member is a disc spring and is interposed between the tip of the sleeve and the liquid-tight seal member. That is.

According to a third aspect of the present invention, in the cylinder according to the first or second aspect, the cylinder body is fitted in a cylinder body and a cap mounting hole formed at a front end of the cylinder body. The second piston guide is made of metal and is sandwiched between the rear end step portion of the cap mounting hole and the front end surface of the cap.

[0008]

In the invention according to claim 1 configured as described above, when the first piston is moved forward, the first cylinder is divided by the first and second cup seal members. , The hydraulic fluid from the second hydraulic chamber is the first and second hydraulic fluid.
Supplied to the brake system. The liquid-tight seal member that defines the front end of the first hydraulic chamber and the first cup seal member are urged by the elastic member in a direction in which they are separated from each other, and are respectively applied to the rear surface of the second piston guide and the front surface of the first piston guide. Abut. As a result, the resin sleeve changes the environment,
Even if the first cup seal member and the liquid-tight seal member do not move while being held at a predetermined position even if they become shorter due to a change with time, the brake fluid of the first cup seal member or the liquid-tight seal member does not move when the brake operation starts. This can be prevented from being consumed by the movement, increasing the ineffective stroke of the first piston, and causing a delay in the braking of the brake, thereby maintaining the initial performance.

In the invention according to claim 2 configured as described above, since the disc spring is interposed between the tip of the resin sleeve and the liquid-tight seal member, the configuration is simple, and the invention is described in claim 1. The effect of the invention can be achieved.

In the invention according to claim 3 configured as described above, the cylinder body is constructed by fitting the cap into the cap mounting hole formed at the front end of the cylinder body,
Since the metallic second piston guide is sandwiched between the rear end step portion of the cap mounting hole and the front end surface of the cap, the position of the rear end surface of the second piston guide does not change, and the liquid-tight sealing member is provided. Can be reliably held in place.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A master cylinder according to a first embodiment of the present invention will be described below with reference to FIGS. In FIG. 1, a cylinder body 1 has a stepped hole-shaped first cylinder 2
The small diameter portion 2a of the first cylinder 2 is open to the booster mounting surface 4 for mounting the booster 3 on the cylinder body 1. At the front end of the cylinder body 1, a cap attachment hole 5 is formed coaxially with the first cylinder 2 such that the diameter of the cap attachment hole 5 increases from the front end of the large diameter portion 2b of the first cylinder 2. A cap 6 is sealed and fitted in the cap mounting hole 5 by an O-ring 7, and a metal annular second piston guide 8 is provided between the rear end step portion of the cap mounting hole 5 and the end surface of the cap 6. It is sandwiched and fixed by a C ring 9 to prevent it from coming off. A single engaging projection is provided in the inner side of the cap mounting hole 5 so as to project in the axial direction, and one end of the cap 6 is engaged with one of three concave grooves formed in the axial direction. Hydraulic chamber 23
To the second brake system, the cap 6 is positioned in the cylinder body 1 so as not to rotate in the desired rotation direction in a rotation direction suitable for supplying hydraulic pressure. On the cap 6, a stepped second cylinder 10 including a bottomed small-diameter portion 10a and a large-diameter portion 10b that fits with the front protrusion of the second piston guide 8 is formed coaxially with the first cylinder 2. Has been done. As described above, the cylinder body 1 is composed of the cylinder body 1 and the cap 6 fitted in the cap mounting hole 5 formed at the front end of the cylinder body 1, and the first cylinder 2 formed in the cylinder body 1 and The second cylinder 10 formed in the cap 6 constitutes a cylinder 68.

The small diameter portion 2a of the first cylinder 2 functions as a first piston guide, and the first piston 11 having a bottomed axial hole 11a is slidably fitted from the front end surface toward the rear. There is. The rear portion of the first piston 11 enters the constant pressure chamber 12 of the booster 3 and is operated by the output shaft 13 of the booster 3. The booster 3 is a booster that boosts the brake fluid pressure generated by boosting the force on the brake pedal. The internal chamber formed by the booster shell 14 is divided into a constant pressure chamber 12 and a variable pressure chamber by a diaphragm. There is. The constant pressure chamber 12 is connected to the intake manifold of the engine via a negative pressure introducing pipe 57 and is maintained at a negative pressure. When the valve is actuated by the pedal depression force and a differential pressure is generated between the constant pressure chamber and the variable pressure chamber, the diaphragm is urged forward, and the output shaft 13 connected to the diaphragm boosts the depression force to move the first piston 11 to the first piston 11. It is designed to push forward. The booster shell 14 is in contact with the booster mounting surface 4 and is fixed by bolts 15. The booster shell 14 is provided with an insertion hole 14a, and the first piston 11 enters the constant pressure chamber 12 through the insertion hole 14a and abuts on the tip of the output shaft 13. The diaphragm is biased rearward by a return spring 16 to retract the output shaft 13 to its original position when it is not operating.

The cylinder 68 is fitted to the first piston 11.
The first cup seal member 18 for partitioning the first hydraulic pressure chamber 19 that supplies the brake hydraulic pressure to the first brake system is brought into contact with the front surface of the small diameter portion 2a of the first cylinder 2 which is the first piston guide, A liquid-tight seal member 21 that defines the front end of the first hydraulic chamber 19 is slidably fitted to the second piston 20 and
It is in contact with the back surface of the piston guide 8. In the large diameter portion 2b of the first cylinder 2, a resin sleeve 17 is loosely fitted between the first cup seal member 18 and the liquid-tight seal member 21, and the first piston 11 is fitted in the sleeve 17. .
Between the tip of the sleeve 17 and the liquid-tight seal member 21,
A disc spring 69, which is an elastic member, intervenes and urges the liquid-tight seal member 21 and the first cup seal member 18 in a direction in which they are separated from each other, and brings the liquid-tight seal member 21 into contact with the back surface of the second piston guide 8. , The first cup seal member 18
It is in contact with the front surface of the piston guide 2a.

A second piston 20 is slidably fitted in an inner peripheral hole of the second piston guide 8, and a front portion of the second piston 20 is fitted in a small diameter portion 10a of the second cylinder 10 so as to be able to move forward and backward. , The rear part is fitted into the sleeve 17 and is fitted into the first hydraulic chamber 19
It is adapted to be pushed in by the hydraulic pressure generated inside the first hydraulic chamber 19 when it enters the inside. Large diameter part 1 of the second cylinder 10
0b, the second cup seal member 22 is brought into contact with the front surface of the front protruding portion of the second piston guide 8, and the large diameter portion 10b.
And the small-diameter portion 10a.
The second cup seal member 22 slidably engages with the second piston 20 to seal between the second cylinder 10 and the second piston 20, and the front of the cylinder 68 is connected to the second brake system to provide the brake fluid pressure. Is divided into a second hydraulic chamber 23 for supplying

On the bottom surface of the axial hole 11 of the first piston 11, a rod 24 having an engaging portion 24a formed at its tip is provided as an engaging member so as to project forward. 25 is a bell-shaped spring seat, and the hole formed at the upper end is the rod 2
4, the rod 24 is brought into contact with the engaging portion 24a of the rod 24 and its forward movement is restricted. Reference numeral 26 is a first compression spring interposed between the flange extended outward at the lower end of the spring seat 25 and the bottom surface of the axial hole 11, and the spring seat 25 is engaged with the engaging portion of the rod 24 by the first set spring force. It is biased forward until it comes into contact with 24a. The engaging member 24 and the spring seat 2 which are arranged between the first piston 11 and the second piston 20 and are relatively movable in the axial direction.
The separating means 70 for urging 5 and 5 in the direction in which they are separated from each other by the first set spring force of the first compression spring 26 to the engagement position where relative movement is restricted is thus the rod 24, the spring seat 25, and the first. It is composed of a compression spring 26 and the like. The separating means 70 may project the rod 24 on the rear end surface of the second piston 20, and bring the tip of the spring seat 25 into contact with the bottom surface of the axial hole 11 of the first piston 11.

Reference numeral 27 denotes a second compression spring interposed between the second piston 20 and the bottom surface of the small diameter portion 10a of the second cylinder 10 which is the front wall of the cylinder 68.
0 is urged rearward by a second set spring force smaller than the first set spring force to move the second piston 20 to the spring seat 25.
Abutting against.

A reservoir 31 is mounted on the upper end of the cylinder body 1, and is fixed to the upper end of the cylinder body 1 by a pin 32. First and second outlets 33, 34 formed in the lower surface of the reservoir 31 are formed in the upper end of the cylinder body 1 to supply the working fluid to the first and second hydraulic pressure chambers 19, 23. 2 It is connected to the supply ports 35 and 36. The first supply port 35 opens in the small diameter portion 11a of the first cylinder 11, and is formed in the first piston 11 in the radial direction toward the axial hole 11a when the first piston 11 is located in the inoperative position. It communicates with the supply hole 37. The second supply port 36 is the second
The piston guide 8 communicates with a hole 38 formed in the front projection in the radial direction, and the hole 38 is formed in the annular portion of the second piston 20 in the radial direction when the second piston 20 is in the inoperative position. It communicates with the supply hole 39 provided. 40 is a filter attached to the bottom of the reservoir 31.

An inner peripheral seal step portion 41 is formed in the opening portion where the first cylinder 2 opens to the booster mounting surface 4 of the cylinder body 1 so as to have an enlarged diameter. The inner peripheral seal step portion 41 has a shoulder portion and an inner peripheral surface, and a front end surface of the booster shell 42 of the booster 3 fixed by abutting on the booster mounting surface 4 and the first inner surface.
The outer peripheral surface of the piston 11 defines a ring-shaped space 43. An annular composite seal member 44 is housed in the annular space 43, and the inner peripheral surface of the composite seal member 44 is brought into sliding contact with the outer peripheral surface of the first piston 20 to form the small diameter portion 2a of the first cylinder 2 and the constant pressure chamber 12. A sliding seal portion 44a is formed for liquid-tightly sealing the space between them, and the composite seal member 4 is formed.
An airtight seal portion 44b is formed on the rear end face of the booster 3 in contact with the front end face of the booster shell 14 of the booster 3 to hermetically seal between the constant pressure chamber 12 and the atmosphere.
On the outer peripheral surface of 4, there is formed a fixed seal portion 44c which is in contact with the inner peripheral surface of the inner peripheral seal step portion 41 and liquid-tightly seals between the small diameter portion 2a and the atmosphere. The bottom surface of the inner peripheral seal step portion 41 communicates with the reservoir 31 through a hole 45 connected to the first supply port 35.

The operation of the embodiment configured as described above will be described. When the brake pedal is stepped on, the valve of the booster 3 operates and a differential pressure acts on the diaphragm, and the output shaft 13 boosts the pedaling force to push the first piston 11. Due to the forward movement of the first piston 11, the supply hole 37 is blocked by the first cup seal member 18 from communicating with the first supply port 35. After the supply hole 37 is blocked, the first piston 11
Of the hydraulic fluid increases the hydraulic pressure of the hydraulic fluid in the first hydraulic chamber 19 and is supplied from the port 46 to the first brake system. The second piston 20 is pushed forward due to the increase in the hydraulic pressure in the first hydraulic chamber 19, and the forward movement of the second piston 20 causes the replenishment hole 39 to be formed by the second liquid-tight seal member 22 into the second replenishment port 3.
After the communication with 6 is cut off, the hydraulic pressure in the second hydraulic chamber 23 increases due to the movement of the second piston 20, and is supplied from the port 47 to the second brake system.

When the brake pedal is released, the output shaft 1
3 is retracted by the return spring 16 of the booster 3 and stopped at the inoperative position. As the output shaft 13 retracts, the first piston 11 causes the engaging portion 24a of the rod 24 to move to the spring seat 25 due to the spring force of the first compression spring 26.
Is retracted until it comes into contact with the second piston 20, and then it is retracted together with the second piston 20 by the spring force of the second compression spring 27, and comes into contact with the output shaft 13 that stops at the non-operating position and is positioned at the non-operating position.

When the hydraulic pressure in the first hydraulic pressure chamber 19 does not rise due to air bleeding or abnormality of the first brake system,
The piston 11 is pushed by the output shaft 13 to move forward against the spring force of the first compression spring 26,
The front end of the second through the flange of the spring seat 25
The piston 20 is pushed forward, and the hydraulic pressure in the second hydraulic chamber 23 is increased. The axial force applied to the second liquid-tight seal member 22 by the hydraulic pressure in the second hydraulic chamber 23 is reliably supported by the second piston guide 8 made of metal. When the hydraulic pressure in the second hydraulic chamber 23 does not rise, the output shaft 13 is moved forward to move the first piston 11 and the spring sheet 25 urged to the forward end by the spring force of the first compression spring 26. The second piston 20 is advanced against the spring force of the second compression spring 27. After the front end of the second piston 20 comes into contact with the bottom surface of the second cylinder 10 and is stopped, the forward movement of the first piston 11 raises the hydraulic pressure in the first hydraulic chamber 19.

At this time, the liquid-tight seal member 21 and the first cup seal member 18 are placed in a direction in which they are separated from each other by the spring force of the disc spring 69 interposed between the tip of the sleeve 17 and the liquid-tight seal member 21. The liquid-tight seal member 21 is urged
Is brought into contact with the back surface of the second piston guide 8, the first cup seal member 18 is brought into contact with the front surface of the first piston guide 2a, and the resin sleeve 17 moves even if it becomes shorter due to environmental changes and changes with time. Therefore, the brake fluid is consumed by the movement of the first cup seal member 18 or the liquid-tight seal member 21 at the start of the brake operation, the ineffective stroke of the first piston 11 is increased, and the brake delay is generated. Absent.

In the above embodiment, the disc spring is replaced by the sleeve 17.
Is interposed between the tip of the and the liquid-tight seal member 21,
A disc spring may be interposed between the rear end of the sleeve 17 and the first cup seal member 18. Further, the sleeve 17 may be divided into two, and compression springs may be interposed at a plurality of positions on the circumference between the divided sleeves.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a master cylinder according to the present embodiment.

FIG. 2 is a cross-sectional view of a portion where a disc spring is interposed between a liquid-tight seal member and a sleeve.

[Explanation of symbols]

1 ... Cylinder body, 2 ... 1st cylinder, 2a ... 1st cylinder small diameter part (1st piston guide), 3 ... Booster,
5 ... Cap mounting hole, 6 ... Cap, 8 ... Second piston guide, 10 ... Second cylinder, 11 ... First piston, 1
6 ... Compression spring, 17 ... Sleeve, 18 ... First cup seal member, 19 ... First hydraulic chamber, 20 ... Second piston, 21 ... Liquid tight seal member, 22 ... Second cup seal member, 23 ... Second Hydraulic chamber, 24 ... Rod, 24a ... Engaging portion, 25 ... Spring seat, 26 ... First compression spring, 27 ... Second compression spring, 31 ... Reservoir, 35
... first supply port, 36 ... second supply port, 37, 39 ... supply hole, 67 ... cylinder body, 68 ... cylinder, 69 ... disc spring (elastic member), 70 ... separating means.

Claims (3)

[Claims] 1. A cylinder body is formed with a cylinder, a first piston guide is provided slidably in a first piston guide provided at a rear end portion of the cylinder, and a first piston guide is provided in a second piston guide provided in an intermediate portion. Two pistons are slidably fitted to each other, and the first and second pistons are fitted to each other, and the cylinder is fitted to the first and second pistons.
First and second supply of brake hydraulic pressure to the brake system, respectively
The first and second cup seal members that partition into the hydraulic chamber are brought into contact with the front surfaces of the first and second piston guides, respectively, and the liquid-tight seal member that defines the front end of the first hydraulic chamber is provided in the first and second cup guide members. (2) A master cylinder having a resin sleeve in which the first piston is fitted between the first cup seal member and the liquid-tight seal member, the master cylinder being brought into contact with the back surface of the two-piston guide. A master cylinder, wherein an elastic member for urging the first cup seal member away from each other is arranged at an appropriate position between the liquid-tight seal member and the first cup seal member. 2. The master cylinder according to claim 1, wherein the elastic member is a disc spring and is interposed between the tip of the sleeve and the liquid-tight seal member. 3. The cylinder body is composed of a cylinder body and a cap fitted in a cap mounting hole formed at a front end of the cylinder body, and the second piston guide is made of metal, and the rear of the cap mounting hole is formed. The cylinder according to claim 1 or 2, wherein the cylinder is sandwiched between the end step portion and the tip end surface of the cap.