JPH10310092A - Vehicle master cylinder - Google Patents

Abstract

(57) [Problem] To provide an inexpensive center port type in which a piston is provided with a relief port in a master cylinder in which a hydraulic pressure chamber is pressurized by pulling a piston rod. SOLUTION: When a piston rod 5a is pulled, in a master cylinder in which the hydraulic chamber 7 is pressurized by the piston 5, a relief port 23 communicating between the supply oil chamber 6 and the hydraulic chamber 7 is connected to the piston rod 5a. A valve member 25 for opening and closing the relief port 23 is provided in the piston 5 to avoid this, and is urged by a spring in the valve closing direction. A stem 28 is disposed to contact the end wall 14 on the chamber 6 side to open the valve member 25.
A dedicated stopper member with which the contact is made is omitted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a master cylinder for generating hydraulic pressure for operating a brake or a clutch in a vehicle such as a motorcycle, and more particularly to a piston which is fitted in a cylinder hole of a cylinder body to define a hydraulic chamber. A piston rod that penetrates the hydraulic chamber and protrudes outside the one end wall of the cylinder body in the axial direction, and when the piston rod is pulled, the hydraulic chamber is pressurized by a piston. .

[0002]

2. Description of the Related Art A master cylinder of this kind is disclosed in
It is already known, as disclosed in US Pat.

[0003]

Generally, a relief port for connecting a reservoir for storing hydraulic oil and a hydraulic chamber in a cylinder body to the master cylinder, and a supply oil chamber in the cylinder body for communication between the reservoir and the supply oil chamber in the cylinder body. And a relief port for communicating between a hydraulic chamber and a replenishing oil chamber in a cylinder body, and a side port type in which a supply port is formed in a side wall of a cylinder body (see the above-mentioned publication). There is known a center port type (for example, see Japanese Patent Publication No. 5-43541) provided with a normally-closed valve member that opens the valve at the retreat limit of the piston.

Although the side port type has a simple structure, the cup seal mounted on the piston may be damaged at the opening edge of the relief port when the piston slides. On the other hand, the center port type has no concern about such damage to the piston cup.
Due to the fact that it is used in a master cylinder that presses the hydraulic chamber by pushing the piston, the structure is complicated and the cost is inevitable.

The present invention has been made in view of such circumstances, and has as its object to provide a piston rod retractable master cylinder to which a center port type can be applied at a low cost.

[0006]

In order to achieve the above object, the present invention provides a piston which is fitted in a cylinder hole of a cylinder body to define a hydraulic chamber, and which is inserted through the hydraulic chamber to form a cylinder body. An axial direction of a piston and a cylinder body of a cylinder in a master cylinder for a vehicle, in which a piston rod protruding outside one end wall in an axial direction is formed, and when the piston rod is pulled, the hydraulic chamber is pressurized by a piston. A supply oil chamber is defined between the other end wall,
A relief port communicating between the replenishing oil chamber and the hydraulic chamber is provided on the piston avoiding the piston rod, a valve member for opening and closing the relief port is provided, and a spring is urged in a valve closing direction to open the relief port. Is characterized in that a stem for contacting the other axial end wall of the cylinder body at the retreat limit of the piston to open the valve member is provided.

According to this feature, at the retreat limit of the piston, the stem can be stopped and the valve member can be opened using the other axial end wall of the cylinder body. Therefore, the structure can be simplified by omitting the stopper member dedicated to stopping the stem.

Further, in addition to the above-mentioned features, the present invention further comprises forming a reservoir for storing hydraulic oil integrally with a cap which is fitted to a cylinder body and constitutes the other end wall in the axial direction, and further comprising the reservoir. A second feature is that a supply port communicating with the replenishing oil chamber is provided.

According to this feature, the cylinder body includes:
It is not necessary to provide a supply port as well as a relief port, so that the structure of the cylinder body can be further simplified and the number of steps can be reduced.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on embodiments of the present invention shown in the accompanying drawings.

FIG. 1 is a longitudinal sectional plan view of a main part of a master cylinder device for a motorcycle, FIG. 2 is an enlarged view of a main part of FIG. 1, and FIG.
FIG. 3 is a sectional view taken along line 3-3 of FIG.

First, in FIGS. 1 and 2, a cylinder body 1 of a master cylinder M of the present invention is fixed to a rod-like steering handle H of a motorcycle.
Similarly, it is arranged adjacent to the inner end of the handle grip Ha with a switch case 2 interposed between the steering handle H and accommodating various switches, and with the cylinder hole 3 parallel to the steering handle H.

The cylinder body 1 integrally has a lever holder 11 which protrudes from the outer periphery of the front side of the vehicle to the side opposite to the handle grip Ha, and a brake lever 12 is supported on the lever holder 11 by a pivot 13. The brake lever 12 has a relatively long operation arm 12a extending from the base supported by the pivot 13 so as to cross the front of the handle grip Ha, and a master cylinder M from the base.
And a relatively short operating arm 12b extending so as to face an end surface opposite to the handle grip Ha.

Further, the cylinder body 1 has an end wall (1a) integrally at one end opposite to the handle grip Ha, and the other end is open. The cap 14 is closed by a cap 14 so as to close the open end. The cap 1 is fitted around the open end of the body 1 via a seal member 16.
4 is a mounting piece 1 protruding radially outward from one side of the outer peripheral portion.
4 a is fixed to the cylinder body 1 with screws 19.

The interior of the cylinder hole 3 is provided with a refill oil chamber 6 on the handle grip Ha side by a piston 5 fitted therein.
And a hydraulic chamber 7 on the opposite side. A cup seal 17 that is in close contact with the inner peripheral surface of the cylinder hole 3 is mounted on the outer periphery of the piston 5, and a return spring 20 that urges the piston 5 toward the replenishing oil chamber 6 is housed in the hydraulic chamber 7. You.

An output port 9 connected to the hydraulic chamber 7 (FIG. 3)
) Is provided on a side wall of the cylinder body 1, and a wheel cylinder (not shown) of a front wheel brake of a motorcycle is connected to the cylinder body 1 via a hydraulic hose 10.

The piston 5 is integrally formed with a piston rod 5a which penetrates the hydraulic chamber 7 and slidably penetrates the end wall 1a, and is slidably tightly contacting the outer peripheral surface of the piston rod 5a. The sealing member 18 is mounted on the end wall 1a. An operating arm 12b of the brake lever 12 is connected to an outer end of the piston rod 5a via a link 21.

As shown in FIG. 3, the cap 14 and
The reservoir 15 disposed on the upper side of the cylinder body 1 is integrally formed using synthetic resin as a material. At the time of the molding, the cap 14 communicates the bottom of the reservoir 15 with the oil supply chamber 6. The supply port 22 is formed in a groove shape.

Referring again to FIGS. 2 and 3, the replenishing oil chamber 6 is attached to the piston 5 while avoiding the piston rod 5a.
A relief port 23 communicating between the hydraulic chamber 7 and the hydraulic chamber 7 is formed. The opening of the relief port 23 on the hydraulic chamber 7 side is
A poppet-shaped valve member 25 formed on a conical valve seat 24 and opening and closing the relief port 23 in cooperation with the valve seat 24.
Is provided. The valve member 25 is urged in a valve closing direction by a valve spring 26 to form a normally closed type.
The retainer 27 supporting the valve spring 26 is pressed and held by the return spring 20 on the end face of the piston 5 on the hydraulic chamber 7 side.

The valve member 25 has a relief port 2
The stem 28 that loosely penetrates 3 is integrally connected. When the piston 5 returns to the retreat limit where the piston 5 contacts the inner surface of the cap 14, the stem 28 contacts the inner surface of the cap 14 to open the valve member 25, and the piston 5 slightly advances from the retreat limit. At this time, the valve member 25 is allowed to close away from the inner surface of the cap 14.

In FIG. 3, reference numeral 29 denotes a lid of the reservoir 15.

Next, the operation of this embodiment will be described.

When the operator turns the operating arm 12a of the brake lever 12 toward the handle grip Ha with the hand holding the handle grip Ha, the operating arm 12b pulls the piston rod 5a through the link 21, The piston 5 is advanced to the hydraulic chamber 7 side. Then stem 28 immediately
Is separated from the inner surface of the cap 14 so that the valve member 2
5 is seated on the valve seat 24 with the urging force of the valve spring 26,
Since the relief port 23 is closed, hydraulic pressure is generated in the hydraulic chamber 7 in accordance with the advance of the piston 5, and the hydraulic pressure is transmitted from the output port 9 to the front wheel brake (not shown) via the hydraulic hose 10 to operate it. Can be.

Next, when the operating force is released from the operating arm 12a, the piston 5 retreats to the replenishing oil chamber 6 side by the urging force of the return spring 20, depressurizes the hydraulic chamber 7, and a front wheel brake inoperative state (not shown) Can be returned to. When the piston 5 returns to the retreat limit, the stem 28 comes into contact with the inner surface of the cap 14 to open the valve member 25, so that the relief port 23 conducts. Therefore, if a shortage of hydraulic oil occurs on the hydraulic chamber 7 side, the hydraulic oil stored in the reservoir 15 is transferred from the replenishing oil chamber 6 to the hydraulic chamber 7 through the relief port 23.
Replenished through. As described above, the valve member 25 is opened by stopping the retreat of the stem 28 using the end wall of the replenishing oil chamber 6 of the cylinder body 1, that is, by using the cap 14. This eliminates the need for a dedicated stopper member, thereby simplifying the structure.

Further, since the reservoir 15 is formed integrally with the cap 14 and the groove-shaped supply port 22 is formed, the cap 14 is fitted to the cylinder body 1 at the same time as the cap 14 and the replenishing oil chamber. 6 can be established, and the cylinder body 1 does not need to be provided with a supply port 22 as well as a troublesome relief port for machining, so that the structure can be further simplified and the number of steps can be reduced.

Further, the pivot 13 of the brake lever 12
Is integrally provided at the end of the cylinder body 1 on the side opposite to the handle grip Ha.
a, which is attached to the lever holder 11 extending to the opposite side to the handle grip Ha.
And the effective length of the operating arm 12a can be made sufficiently long to greatly increase the lever ratio, that is, the ratio of the effective length of the operating arm 12a to the effective length of the operating arm 12b. can do. Therefore, the operation load on the brake lever 12 can be reduced, and the brake operation can be performed lightly.

The present invention is not limited to the above embodiment, and various design changes can be made without departing from the gist of the present invention. For example, the valve member 25 and the stem 28 can be separated from each other. Further, the present invention can be applied to a master cylinder device for a clutch.

[0028]

As described above, according to the first aspect of the present invention, a piston which is fitted in a cylinder hole of a cylinder body and defines a hydraulic chamber is provided with a shaft of the cylinder body passing through the hydraulic chamber. In a vehicle master cylinder, the piston chamber presses the hydraulic chamber when the piston rod is towed when the piston rod is towed. A replenishing oil chamber is defined between the end wall and a relief port communicating between the replenishing oil chamber and the hydraulic chamber is provided on the piston avoiding the piston rod, and a valve member for opening and closing the relief port is provided. A spring is urged in the valve closing direction, and a stem is provided at the relief port to open the valve member by contacting the other axial end wall of the cylinder body at the limit of retraction of the piston. Therefore, in the retreat limit of the piston, the stem can be stopped and the valve member can be opened using the other end wall in the axial direction of the cylinder body, so that the stopper member dedicated to stop the stem and omitted is omitted. As a result, the structure can be simplified, and the cost can be reduced.

According to a second feature of the present invention, a reservoir for storing hydraulic oil is formed integrally with a cap which is fitted to the cylinder body and constitutes the other end wall in the axial direction. The supply port that communicates with the oil supply chamber is provided, so there is no need to provide a supply port in the cylinder body, as well as a relief port. Therefore, the structure of the cylinder body is further simplified and the number of steps is reduced. And can contribute to further cost reduction.

[Brief description of the drawings]

FIG. 1 is a vertical sectional plan view of a main part of a master cylinder device for a motorcycle according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 1;

[Explanation of symbols]

 1 ... Cylinder body 1a ... One end wall in axial direction 3 ... Cylinder hole 5 ... Piston 5a ... Piston rod 6 ... Replenishing oil chamber 7 ... ···· Hydraulic chamber 14 ··· Cap (the other end wall in the axial direction) 15 ··· Reservoir 22 ··· Supply port 23 ··· Relief port 25 ··· Valve member 28 ···・ Stem

Claims (2)

[Claims] 1. A piston (5) fitted into a cylinder hole (3) of a cylinder body (1) and defining a hydraulic chamber (7). ), A piston rod (5a) protruding out of the one end wall (1a) in the axial direction is formed.
In the vehicle master cylinder, the oil supply chamber (6) is provided between the piston (5) of the cylinder hole (3) and the other axial end wall (14) of the cylinder body (1).
And a relief port (23) communicating between the supply oil chamber (6) and the hydraulic chamber (7) is connected to the piston rod (5).
a) is provided on the piston (5) avoiding a), and a valve member (25) for opening and closing the relief port (23) is provided.
This is spring-biased in the valve closing direction, and the relief port (23)
The piston body (1)
A stem (28) for contacting the other end wall (14) in the axial direction to open the valve member (25).
Master cylinder for vehicles. 2. A reservoir (15) for storing hydraulic oil integrally with a cap (14) fitted on the cylinder body (1) and constituting the other axial end wall thereof. At the same time, the reservoir (1
Supply port (2) communicating the supply oil chamber (6) with the supply oil chamber (6)
A master cylinder for a vehicle, wherein 2) is provided.