JPH1067314A - Master cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a master cylinder which has a low sliding resistance of a slider which receives a braking operation force and a high sealing force in a standby state. An elastic cup seal (31) supported by a guide (30) for guiding a slider (22) integral with a piston (21) in a cylinder (11) to seal between the guide and the slider, and y Piston 2 facing in opposite directions
1 is provided with a ring plate 33 which is pressed by the return movement of 1 to compress the cup seal 31.

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 hydraulic brake device, and more particularly to a master cylinder for driving a piston in a cylinder from the outside, which is connected to the piston and protrudes from a cylinder body to the outside. The present invention relates to a master cylinder having a slider.

[0002]

2. Description of the Related Art In general, a slider is connected to a brake pedal via a link, or a booster connected to a brake pedal via a link.
When the key pedal is depressed, the slider is driven so as to be pushed into the cylinder body. At this time, a piston that divides the cylinder space into an inner space and an outer space moves in a direction to shrink the inner space and expand the outer space (a direction in which a brake pressure is generated), and the brake fluid in the inner space is pressurized to make the inner space. The brake is supplied to the wheel brake through an outlet port communicating with the space, and simultaneously from the brake fluid reservoir through a reservoir port communicating with the outer space and the brake fluid reservoir. The liquid is drawn into the outer space; Also, the return spring is compressed. When the brake pedal is released, the piston is driven in the return direction (brake pressure release direction) by the repulsive force of the return spring, and the brake fluid returns from the wheel brake to the inner space. It moves and at the same time the brake fluid in the outer space is pumped out to the brake fluid reservoir. The slider returns to the position most protruding from the cylinder body.

The slider is integral with the piston, passes through the outer space, penetrates a slider guide that closes an end of the cylinder space, and projects outside the cylinder body.
The slider guide is provided with a ring-type cup seal for hermetically sealing a gap between the slider guide hole and the slider. This type of seal is disclosed in Japanese Utility Model Publication No. 4-4927. In order to prevent leakage of liquid at the seal portion or intrusion of outside air into the outer space, it is necessary to ensure close contact between the ring-type cup seal, the slider, and the slider guide.

[0004]

In particular, when filling the master cylinder and the brake fluid therefrom with the brake fluid, or when replacing the brake fluid, the vacuum pump is supplied to the brake fluid reservoir. And the vacuum piping is evacuated to a predetermined negative pressure, and the brake is switched by switching the cock.
Ink is supplied, but if the seal is incomplete at the time of evacuation, the outside air is sucked in,
A problem arises in that suction cannot be performed to a predetermined negative pressure. If the brake fluid is filled without suctioning to a predetermined negative pressure, air (bubbles) may remain in the brake pipe.
In order to ensure the evacuation, it is preferable to increase the seal between the slider guide and the slider.

[0005] However, as the sealing force (adhesion force) increases, the sliding resistance of the slider increases, which is not preferable for driving the piston. For example, if you increase the sealing force,
The spring force of the spring must be designed to be strong, and if so, the brake operating force for pushing the slider against the repulsion force of the spring must also be increased.

Accordingly, the sealing force when there is no braking operation is strong, and the resistance against sliding of the slider is low.
Is desirable.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a master cylinder in which the sliding resistance of the slider is low and the sealing force when the slider is not operated is strong.

[0008]

Means for Solving the Problems (1) A master cylinder according to the present invention has a cylinder body (1) having a cylinder space (11) extending in the y-direction and having one end open in the direction, and a cylinder space (11). Piston means (20) including a piston (21) for dividing the cylinder body in the y-direction and a slider (22) extending from the one end of the cylinder space to the outside of the cylinder body along the y-direction continuously therefrom;
2) has a through hole and is connected to the cylinder body (1),
Cylinder body at the end of the cylinder space (11)
Guide member (30) facing end face of (1); Guide member (30)
And is opposed to the end face of the cylinder body (1),
An elastic seal member (31) for sealing between the guide member (30) and the slider (22); the piston means (20) is connected to the piston (21) by the one end of the cylinder space (11). A spring member (32) biasing in a direction approaching the cylinder; and a piston (21) inserted between the end face of the cylinder body (1) and the seal member (31).
A pressure member (33) for pressing the seal member (31) by being pushed by the piston means (20) by the movement of the cylinder space (11) to the vicinity of the one end. In addition, in order to facilitate understanding, the symbols of the corresponding elements in the embodiments shown in the drawings and described later are added in the parentheses for reference.

According to this, when no force is applied to the slider (22) from the outside of the cylinder body (1), the piston (21) is moved to the one end of the cylinder space (11) by the spring member (32). At a close position, the pressure member (33) is pressed by the piston means (20) to press the seal member (31). Since the direction of this pressurization is the moving direction y of the piston (21), the seal member (31) is compressed in the y direction, and thereby the direction is orthogonal to the y direction, that is, toward the outer surface of the slider (22). Presses against the outer surface of the slider (22),
The sealing force of the seal member (31) on the slider (22) is strong.

When the slider (22) is driven in the direction of being pushed into the cylinder body (1), initially, as described above, the seal is driven.
Although the pressing force of the pressing member (33) against the seal member (31) decreases with the movement of the piston means (20), the piston means (20) moves a small distance to move the piston means. (20)
No longer presses the pressing member (33), the sealing member (31) extends in the y direction, and accordingly, the slider of the sealing member (31)
The pressing force in the direction toward the outer surface of (22) decreases. As a result, the sliding resistance of the slider (22) decreases, and the slider (22) can move smoothly even with a relatively small pushing force.

As described above, in the master cylinder of the present invention,
In a stationary state (standby position) where no external force acts on the slider (22), the seal force of the seal member (31) with respect to the slider (22) is strong, and the seal force decreases at a position outside the standby position. Therefore, the sliding resistance of the slider is low.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

(2) The piston means (20) is provided with a hole (23) penetrating the slider (22) in the direction perpendicular to the y direction in the immediate vicinity of the piston (21), and is inserted into the hole (23). ) Further includes a pin (24) for pushing the pressing member (33) by moving the cylinder space (11) to the vicinity of the one end, the width in the y direction being smaller than the width in the y direction of the hole (23).

According to this, the piston is provided via the pin (24).
(21) presses the pressure member (33) to press the seal member (31) in the y direction.

(3) The piston means (20) is provided in the cylinder space.
(11) of the piston (21) for communicating between the outer space (11a) on the one end side divided by the piston (21) and the inner space (11b) on the opposite side of the piston (21). Opened communication hole (25), and the pin (24) penetrating therethrough
The piston (21) and the pin (2
A valve member (26) that closes when the stem (26a) hits the pin (24) when the piston (21) approaches the pin (24) in accordance with the relative movement with respect to the pin (24) and opens and separates the through hole (25). The cylinder body (1) further includes a reservoir port (34) communicating with the outer space (11a) and the brake fluid reservoir (70);
And an outlet port communicating with the inner space (11b) for supplying and discharging the brake fluid to and from the wheel brake.
(35).

According to this, when no force is applied to the slider (22) from the outside of the cylinder body (1), the piston (21) is moved to the one end of the cylinder space (11) by the spring member (32). Closed (standby position) and the piston means (2
The pin (24) pressed in step (0) presses the pressing member (33), whereby the pressing member (33) presses the seal member (31). At this time, since the stem (26a) of the valve member (26) is in contact with the pin (24), the valve member (26) has a through hole (25), and the outer space (11a) of the cylinder space (11) is open. ) And inner space (11b) are through holes (25)
Through. That is, the reservoir port (34) opened in the outer space (11a) and the outlet port (35) opened in the inner space (11b) communicate with each other, and the outlet port (3) is opened.
5) Wheel brake piping and brake fluid reservoir (7)
0), and the cylinder space of the master cylinder and the wheel brake piping are equalized to the hydraulic pressure (atmospheric pressure) of the brake fluid reservoir (70). In the brake fluid pipe from the master cylinder to the wheel brake, if the brake fluid is too large or too small due to fluid leakage, temperature change (expansion / shrinkage of the space inside the pipe), etc. In this case, the excessive amount of the brake fluid is automatically returned to the brake fluid reservoir due to the above-mentioned communication between the wheel brake / the brake fluid reservoir, and the reservoir is used when the fluid is insufficient. -The liquid in the bath flows automatically. In this state, since the seal member (31) is compressed in the y direction, the seal member (31)
The sealing force against the slider (22) is strong, and the function of preventing liquid leakage or air inflow at the sealing portion is high.

When the slider (22) is driven in the direction of being pushed into the cylinder body (1), the width of the pin (24) in the y-direction is
Since the pin (24) is smaller than the width in the y direction of (23), at first, the pin (24) and the valve member (26) contacting the pin remain at the original position, and the piston (21) and the slider (22) move in the pushing direction. I do. At this time, the valve member (26) moves relative to the piston (21) in a direction to close the through hole (25). Next, the slider (2) contacts the pin (24) with the inner surface of the hole (23) on the slider side.
2) drives the pin (24) in the pushing direction. Thereby, with the communication hole (25) closed, the piston (21), the pin (24) and the slider (22) move in the pushing direction, and the inner space (11b)
Brake fluid is pumped through the outlet port (35) to the wheel brake, and at the same time, the reservoir is placed in the outer space (11a).
The brake fluid of (70) is inhaled. When the operating force applied to the slider (22) disappears, the piston (21) moves in the return direction in which the slider (22) projects from the cylinder body (1) due to the fluid pressure in the inner space and the repulsive force of the spring member (32). It moves and finally returns to the aforementioned standby position. In this process, the brake fluid supplied to the wheel brake returns to the inner space (11b), and the outer space (11a)
The brake fluid that has been sucked in returns to the reservoir (70). Since the pressure member (33) is not pushed by the pin (24), the pressure contact force of the seal member (31) in the direction toward the outer surface of the slider (22) is low, so that the pressure of the liquid in the inner space is reduced. The sliding resistance of the return movement of the slider (22) and the piston (21) due to the repulsive force of the spring member (32) is low, and the piston (21) returns smoothly and promptly.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0018]

FIG. 1 shows an embodiment of the present invention. A cylinder hole 11 is formed in the cylinder body 1, and a second return spring (compression coil spring) 52, a second piston assembly 40, a first return spring (compression coil spring) are opened from the left end opening. ) 32 and the first piston assembly 20 are inserted, and the opening at the right end is closed by the cup-shaped slider guide 30. In the first piston assembly 20, a slider 22 is integrally continuous with a first piston 21, and a hole 23 in a diametric direction orthogonal to a direction y in which a central axis of a cylinder hole 11 extends is formed in a connecting portion between the two. A slit-like flow groove 27 is formed between the hole 23 and the land (flange shape) of the piston 21 in the same direction as the hole 23 and opened in the hole. Cylinder hole 11
Is smaller than the diameter of the slider 22, and a pin 24 longer than the diameter of the slider 22 is inserted into the hole 23. Since the width of the hole 23 in the y direction is larger than the diameter of the pin 24, the pin 24 Can move to. However, the slit-shaped flow grooves 2
7 is smaller than the diameter of the pin 24, so that the pin 24 does not fit into the flow groove 27.

The diameter of the slider 22 is considerably smaller than the diameter of the cylinder hole 11, and the slider guide 30 has a hole through which the slider 22 passes. The slider 30 penetrates the guide 30 and protrudes out of the cylinder body 1. ing.

A hole having a diameter larger than that of the cylinder hole 11 is formed at the right end in FIG. 1 of the cylinder body 1, and a bottom surface 38 of the large diameter hole is formed at an end surface of the cylinder body 1 at the right end of the cylinder hole 11. It has become. This end face (bottom 3
8) The reservoir channel 12 is open. A reservoir port 34 communicating with the flow path 12 is formed on the bottom surface 38 of the large-diameter hole. A ring plate 33 through which the slider 22 penetrates is inserted into the large-diameter hole, and the ring-shaped cup seal 31 is pressed against the slider 22 and the guide 30 on the inner and outer peripheral surfaces of the opening of the guide 30. The cup seal 31 faces the ring plate 33. The guide 30 is inserted into the large-diameter hole in a liquid-tight manner, and is locked to the cylinder body 1 by a stopper plate 36.

FIG. 1 shows that the piston 21 pushed to the right by the first return spring 32 pushes the pin 24 to the right, and the pin 24 pushes the ring plate 33 to the right. The plate 33 moves to the right from the bottom surface 38 of the large-diameter hole, compresses the cup seal 31 in the y direction, and hits the left end surface of the guide 30. Cup seal 31
When the compressive force in the y direction is not applied (when the ring plate 33 is in contact with the bottom surface 38), the thickness (in the y direction) is larger than the depth of the opening of the cup-shaped guide 30, but FIG. In the state shown in the figure, the cup seal 31 is compressed in the y-direction by the ring plate 33 and has substantially the same thickness as the depth of the opening of the cup-shaped guide 30. The sealing force (sealing force) of the cup seal 31 for tightening the slider 22 in the diametric direction is larger than when the compressive force in the y direction is not applied.
large.

The piston 21 is roughly in the shape of a cup with a footrest, and its land (flange shape) corresponds to the footrest of the cup. At the center of the land, a flow hole 25 opened to the left opening of the cup is formed, and communicates with a flow groove 27 on the left side of the hole 23 to open the hole 23 described above. The stem 26a of the check valve 26 passes through the through hole 25, and the stem 2
The tip (right end face) of 6a hits the pin 24 and the stem 26a
Is longer than the length of the through hole, the check valve 26 is
Is open. That is, a space (outer space) 11 a of the cylinder hole 11 to the right of the land of the piston 21 communicates with the left opening (cup space) of the piston 21 through the through hole 25. The cup space (left opening) is flow
Through the hole 28c (FIGS. 2 and 3) of the valve 28, the cylinder hole 11 communicates with a space (inside space) 11b on the left side of the land of the piston 21.
Since the first outlet port 35 for supplying and discharging the brake fluid pressure to the first set of wheel brakes (not shown) is open, the reservoir communicating with the brake fluid reservoir 70 is eventually opened. −
The flow path 12 is formed by a reservoir port 34, an outer space 11a,
Through the through hole 25, the internal space (cup space) of the piston 21 and the ball 28c (FIGS. 2 and 3) of the float valve 28, and further through the internal space 11b, the first set of wheel brakes To the first outlet port 35 for supplying and discharging the brake fluid pressure.

The left end of the first return spring 32 which pushes the first piston assembly 20 rightward in FIG.
The rightmost partition piston 49 of the piston assembly 40 is supported.

The main body of the second piston assembly 40 is a partition piston 49, a stem 42 integral therewith, and a piston 41 for generating wheel brake pressure integral therewith. A slit-like hole 43 for defining the stem 4 like the pin hole 23 described above.
2, and a pin 44 penetrates the hole 43.
The pin 44 is connected to the outside of the cylinder body 1 (reservoir 7).
0) and is fixed to the cylinder body 1. When the piston assembly 40 moves to the left in FIG.
d) just before hitting the bottom of step d), and when the piston assembly 40 moves to the right, just before the partitioning piston 49 closes the first outlet port 35, The position of the pin 44, the position of the hole 43 through which the pin 44 penetrates, and the width in the y direction are determined so as to be held by the pin 44. Between the hole 43 and the land of the piston 41, there is a flow groove 47 similar to the flow groove 27 described above. Second
The piston 41 and the float valve 48 of the piston assembly 40
The structure up to this point is the same as that of the first piston assembly described above.

The partitioning piston 49 divides the cylinder hole 11 into two parts on the left and right in FIG.
The second piston assembly 40 is divided into a reservoir pressure space 11c that can be functionally associated with the outer space 11a and a brake pressure space 11d that can be functionally associated with the inner space 11b. No matter where the second piston assembly 40 is located within the movement range defined by the pin 44 and the hole 43, the reservoir port 54 is opened at a position communicating only with the reservoir pressure space 11c. Through this port 54, the reservoir pressure space 11c is always in communication with the brake fluid reservoir 70. A second outlet port 55 communicating with the brake pressure space 11d is connected to a pipe for supplying and discharging brake fluid pressure to a second set of wheel brakes (not shown).

The slider 22 is provided with an output shaft of a booster (not shown) for generating a pushing pressure corresponding to the pushing force of a brake pedal (not shown) or an operator of a link mechanism connected to the brake pedal. When the brake pedal is depressed, the slider 22 is pushed into a position corresponding to the depressing force. At this time, the slider 22 moves together with the slider 22 to the left in FIG. The assembly 40 is driven to the left through the first return spring 32 and the brake fluid pressure in the inner space 11b.
The inner space 11b of the pistons 21 and 41 at this time
The brake pressure of the first and second sets of wheel brakes is increased by pressurizing the brake pressure space 11d. Since the outer space 11a is expanded, the brake fluid flows into the outer space 11a from the reservoir 70. Since the reservoir pressure space 11d has substantially no volume change, there is substantially no movement of the brake fluid between the reservoir 70 and the reservoir 70. When the pushing force applied to the slider 22 disappears, the first and second sets of piston assemblies 40 are moved to the positions shown in FIG. 1 by the wheel brake pressure and the repulsive forces of the first and second return springs 32 and 52. Return to the position shown in.

Since the float valves 28 and 48 have the same configuration, the float valve 28 will be described with reference to FIG. The float valve 28 is a small chamber provided with a hole (flow hole) in the axial (left and right) direction, and a resin float 28a having an orifice is housed in the small chamber. Can move on. The specific gravity of the float 28a is blurred
It is almost the same as the specific gravity of key oil. Float 28a
Is in contact with the left wall of the small chamber, a plurality of holes 28b provided in the left wall and a hole 28c provided in the right wall allow the flow of the brake fluid between the check valve 26 and the inner space 11b. Although not substantially limited, when the float 28a is in contact with the right wall of the small chamber, the float 28a closes the hole 28c of the right wall of the small chamber, so that there is a vibration between the check valve 26 and the inner space 11b. -The flow of the liquid is restricted through the orifice in the center of the float 28a.

When the slider 22 is pushed, the check valve 2
Until the 6 is closed, the inner space 11b is shaken.
The brake fluid flows through the open check valve 26 to the outer space 11a, and is supplied from the inner space 11b to the wheel brakes by the amount of the brake fluid flowing from the inner space 11b to the outer space 11a. The brake fluid volume is lost. The float 28 moves due to the flow of the brake fluid from the inner space 11b to the outer space 11a, and closes the hole 28c on the right wall of the small chamber to block the flow of the brake fluid from the inner space 11b to the outer space 11a. Limit the above loss. When the pushing force is released and the piston 21 returns to the standby position, the check valve 26 is opened due to the pressure difference between the inner space 11b and the outer space 11a, and the brake fluid flows from the outer space 11a to the inner space 11b. When flowing, the float 28 moves by the flow of the brake fluid and opens the hole 28c on the right wall of the small chamber, so that the flow of the brake fluid from the outer space 11a to the inner space 11b is increased. Is not controlled by

Next, referring to FIGS. 2 and 3, the seal function of the cup seal 31 when the slider 22 is at the standby position shown in FIG. 1 and the seal function when the slider 22 is pushed in. The following describes the control function.

First, reference will be made to FIG. 2 showing the same state as FIG. 1 showing the standby state. In the standby state (FIG. 2), the piston 21 is pushed to the rightmost by the first return spring 32, and the ring plate 33 is pushed through the pin 24 to push the cup-shaped guide 30, and the cup-shaped guide 30 is pushed. Compresses the cup seal 31 to the right and the ring plate 3
3 strikes the left end face of the cup-shaped guide 30, whereby the leftward movement of the piston 21 is regulated and the amount of compression of the cup seal 31 in the y direction is regulated.

The cup seal 31 is pressed against the outer peripheral surface of the slider 22 by the compression in the y direction so as to extend in a direction perpendicular to the y direction, that is, in a direction toward the outer peripheral surface of the slider 22 and the inner peripheral surface of the guide 30. Cup seal 31
Of the slider 22 and the guide 30 is strong.

Since the stem 26a of the check valve 26 contacts the pin 24, the check valve 26 has a through hole 25,
The outer space 11a and the inner space 11b communicate with each other through the through hole 25. That is, the reservoir port 34 opened to the outer space 11a communicates with the first outlet port 35 opened to the inner space 11b, and the first outlet port 3 is opened.
The brake fluid reservoir 70 is in communication with the first set of wheel brake piping communicating with the brake fluid 5, and the cylinder hole 11 of the master cylinder and the wheel brake piping are in communication with the brake fluid reservoir.
The fluid pressure (atmospheric pressure) of the chamber 70 is leveled. In the brake fluid piping from the master cylinder to the first set of wheel brakes, if the brake fluid is excessive or insufficient (fluid with respect to the atmospheric pressure) due to fluid leakage, temperature change (expansion / contraction of the space inside the pipe), etc. (Increase / decrease in pressure), the excess brake fluid is automatically returned to the brake fluid reservoir due to the communication between the wheel brake / brake fluid reservoir and the fluid. In case of shortage, the reservoir liquid automatically flows. In this state, since the cup seal 31 is compressed in the y direction, the slider 22 and the guide 3 of the cup seal 31 are compressed.
The seal force against zero is strong, and the function of preventing leakage of liquid at the seal portion or preventing inflow of air at the time of evacuation at the time of filling the brake liquid is high.

Next, a description will be given with reference to FIG. 3 showing a state in which the slider 22 is driven to be pushed.

When the slider 22 is driven to be pushed in, the seal force is initially strong (FIG. 2) as described above, but the ring plate 33 with respect to the cup seal 31 with the leftward movement of the piston assembly 20. Of the piston assembly 20
The pin 24 moves to the ring plate 3
3 is no longer pressed, the cup seal 31 extends in the y direction,
The ring plate 33 is pushed back to the bottom surface 38 (FIG. 3). Accordingly, the slider 2 of the cup seal 31
2 and the pressing force in the direction toward the outer peripheral surface of the guide 30 decreases. As a result, the sliding resistance of the slider 22 decreases, and the slider 22 moves smoothly even with a relatively small pushing force.

Since the diameter of the pin 24 is smaller than the width of the hole 23 in the y direction, initially, the pin 24 and the check valve 26 contacting the pin 24 remain at the original position, and the piston 21 and the slider 22 are moved in the pushing direction (left direction). Move to At this time, the check valve 26 moves relative to the piston 21 in the direction in which the flow hole 25 is closed. Next, the inner surface of the hole 23 on the slider side contacts the pin 24, and the slider 22
Is driven in the pushing direction. As a result, the piston 21, the pin 24 and the slider 2 are closed with the flow hole 25 closed.
2 moves in the pushing direction, and the brake fluid in the inner space 11b is pumped to the first set of wheel brakes through the first outlet port 35, and at the same time, the communication passage 12 and the reservoir are introduced into the outer space 11a. Through reservoir 34, reservoir 70
Is inhaled. When the pushing force applied to the slider 22 disappears, the piston 21 moves in the return direction in which the slider 22 projects from the cylinder body 1 due to the hydraulic pressure in the inner space 11b and the repulsive force of the first return spring 32, and finally It returns to the above-mentioned waiting position (FIG. 2).

In the return process, the brake fluid supplied to the first set of wheel brakes returns to the inner space 11b, and the brake fluid sucked into the outer space 11a is transferred to the reservoir 70. Return.

Since the ring plate 33 is not pushed by the pin 24, the ring plate 33 is pushed back to the left by the extension of the cup seal 31 to return to the original shape, and the right end of the cylinder body 1 is enlarged. It is pressed against the bottom surface 38 of the diameter hole. Since the cup seal 31 has a low pressure contact force in the direction toward the outer peripheral surface of the slider 22 due to the extension in the y direction, the slider 22 returns due to the liquid pressure in the inner space 11b and the repulsive force of the first return spring 32. , The sliding resistance is low, and the piston 21 returns smoothly and promptly.

As described above, the slider 22 is subjected to an external force (brake).
In the stationary state (standby position: FIGS. 1 and 2) where no keying force is applied, the seal of the cup seal 31 with respect to the slider 22).
Since the sealing force is high and the sealing force is low at a position outside the standby position (FIG. 3), the sliding resistance of the slider 22 is low.

In the above embodiment, the piston 21 is
When it is in the standby position, communication is made between the outer space 11a communicating with the reservoir port 34 and the inner space 11b communicating with the outlet port 35. When it is in the position, it is located on the inner space 11b side (the left side of the piston 21), and when the piston 21 is pushed in, it becomes the position of the outer space 11a (the right side of the piston 21). 4
By providing the compensating port disclosed in Japanese Patent Application Laid-Open No. 927, the check valve 26 and the pin 24 can be omitted. If omitted, the ring plate 33 may be pushed by the piston 21.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a vertical section of an embodiment of the present invention, showing a standby state in which a piston is at a standby position.

FIG. 2 is an enlarged sectional view of a right end portion of the master cylinder shown in FIG. 1 and shows a standby state in which a piston 21 is at a standby position.

3 is an enlarged sectional view of a right end portion of the master cylinder shown in FIG. 1, showing a state in which a brake operation force is applied to a slider 22 and a piston 21 has left a standby position.

[Explanation of symbols]

1: Cylinder body 11: Cylinder space (hole) 11a: Outer space 11b: Inner space 11c: Reservoir pressure space 11d: Brake pressure space 12: Reservoir flow path 20: First piston assembly 21: First 1 piston 22: Slider 23: Slider through hole 24: Pin 25: Flow hole 26: Check valve 26a: Stem 27: Slit flow groove 28: Float valve 28a: Float 28b: Left wall hole 28c : Right wall hole 30: Slider guide 31: Cup sheath
Screw (seal member) 32: first return spring (spring member) 33: ring plate (pressurizing member) 34: reservoir port 35: first outlet port 36: stopper plate -G 37: 38: Cylinder large diameter bottom surface 39: 40: Second piston assembly 41: Second piston 42: Stem 43: Slit hole 44: Pin 45: Flow hole 46: Check valve 46a: Stem 47 : Slit-shaped flow groove 48: Float valve 49: Partition piston 52: Second return spring (compression coil spring) 54: Reservoir port 55: Second outlet port 70: Brake liquid Reservoir

Claims (3)

[Claims] A cylinder body extending in the y-direction and having a cylinder space open at one end in the direction; a piston in the cylinder space which divides the cylinder space in the y-direction; Outside of y
Piston means including a slider extending along a direction; a guide member having a hole through which the slider penetrates, being coupled to the cylinder body and facing the end surface of the cylinder body at the other end of the cylinder space; supported by the guide member A spring member which opposes the end surface of the cylinder body and seals between the guide member and the slider; a spring for urging the piston means in a direction in which the piston approaches the one end of the cylinder space. A pressure member inserted between the end surface of the cylinder body and the seal member, and pressed by the piston means to press the seal member by the movement of the piston toward the one end of the cylinder space. A master cylinder comprising; 2. The piston means includes a hole which penetrates the slider in a direction perpendicular to the y direction in the vicinity of the piston, and is inserted into the hole. Press, the width in the y direction is y
The master cylinder of claim 1, further comprising a pin smaller than the width in the direction. 3. The piston means includes a through hole formed in the piston for communicating between an outer space on one end side of the cylinder space defined by the piston and an inner space on the opposite side of the piston. And a valve member having a stem penetrating therethrough and facing the pin, and closing when the piston comes into contact with the pin according to the relative movement between the piston and the pin, the stem hits the pin and opens and closes the through hole. A cylinder body for supplying brake fluid to a wheel brake communicating with the outer space and the brake fluid reservoir, and a wheel brake communicating with the inner space. 3. The master cylinder of claim 2, including an outlet port for draining.