JPH0355475Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a hydraulic master cylinder for vehicles that hydraulically operates brakes and clutches, and in particular includes a reservoir in a hydraulic chamber in the cylinder hole. The present invention relates to a center valve type hydraulic master cylinder equipped with a valve body that blocks a communication hole that supplies hydraulic fluid to generate pressure fluid in a hydraulic chamber.

[Conventional technology]

The conventional center valve type hydraulic master cylinder is
For example, as disclosed in Japanese Utility Model Application Publication No. 61-67272,
A hydraulic pressure chamber is defined between the bottom of the cylinder hole and the piston, a communication hole is provided in the bottom wall of the cylinder hole to communicate the hydraulic pressure chamber and the reservoir, and a valve stem is connected to the guide hole of the piston. A rubber annular seal member that becomes a valve body is fitted to the tip, and as the piston moves forward, the valve stem is moved to the bottom side of the cylinder hole, and the annular seal member is brought into contact with the valve seat on the outer periphery of the communication hole. There are known devices in which pressurized liquid is generated in a hydraulic chamber whose communication with a reservoir is cut off.

[Problem that the invention attempts to solve]

However, the above-mentioned hydraulic master cylinder has poor durability because the annular seal member is made of rubber as mentioned above, and deterioration of sealing performance due to repeated operation cannot be avoided.

Therefore, an object of the present invention is to provide a center valve type hydraulic master cylinder that can exhibit excellent sealing performance over a long period of time.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention includes a hydraulic pressure chamber defined in a cylinder hole by inserting a piston, and a communication hole for supplying working fluid to the hydraulic pressure chamber. In a center valve type vehicle hydraulic master cylinder in which a communicating hole is closed by a valve body supported by a stem to generate pressure fluid in a hydraulic chamber, a spherical valve head serving as a valve body is attached to one end of the valve stem. It is characterized in that it is formed protrudingly.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In a center valve type hydraulic master cylinder 1, a piston 5 pushed by a push rod 4 is fluid-tightly and movably inserted into a cylinder hole 3 formed in a cylinder body 2, and the piston 5 is movably inserted into a cylinder hole 3 formed in a cylinder body 2. A hydraulic chamber 6 is defined between the piston 5 and an output port 7 connected to the hydraulic chamber 6, and a hose connected to a brake or clutch is connected to the output port 7.

The piston 5 has cup seals 8a, 8 at the front and rear.
An annular oil supply chamber 9 is formed on the outer periphery of the small diameter shaft portion 5a between the cup seals 8a and 8b.

An auxiliary oil tank 10 is integrally provided in the upper part of the cylinder body 2 , and a synthetic resin reservoir 11 is fitted into the auxiliary oil tank 10 . It's communicating.

The small diameter shaft portion 5a of the piston 5 is provided with a through hole 13 that opens into the oil supply chamber 9, and the head thereof is provided with a valve hole 14 that opens into the hydraulic pressure chamber 6.
14 communicate with each other through a communication hole 15 formed on the central axis.

A return spring 16 that urges the piston 5 in the backward direction is installed in the hydraulic chamber 6, and a retainer 17 that supports both ends of the spring 16 is installed in the hydraulic chamber 6.
The shaft portion 1 of the valve stem 19 is located between the heads of the valve stem 18.
9a is inserted and arranged.

The valve stem 19 has a circlip 20 fitted to the tip of the shaft portion 19a, which is retained by a retainer 17 on the side of the hydraulic pressure chamber 6, and a large-diameter head portion 1 connected to the rear portion.
9b is arranged in the valve hole 14, and the head 19b
A valve spring 21 is compressed between the retainer 18 on the piston 5 side and urges the valve stem 19 in the backward direction.

A plurality of arc-shaped oil grooves 22 are provided on the outer periphery of the head 19b, and a spherical valve head 23 that closes the communication hole 15 of the piston 5 projects from the rear surface.

This spherical valve head 23 is a valve body made by protruding a part of a metal ball 24 such as a steel ball that is cast into the head 19b when the halve stem 19 is molded from synthetic resin. In the non-operating state shown in the figure, the valve seat 25 is spaced a predetermined distance from the tapered valve seat 25 formed between the valve hole 14 and the communication hole 15, and the hydraulic chamber 6 and the oil supply chamber 9 are connected to the through hole 13 and the communication hole 15. They communicate through the hole 15, the valve hole 14, and the oil groove 22.

Next, the operation of this embodiment configured as described above will be explained.

The piston 5 is in the backward limit position shown in FIG. 1 in the non-operating state, and as described above, the spherical valve head 23 and the valve seat 25 are separated from each other, and the hydraulic pressure chamber 6 and the oil supply chamber 9 are separated from each other.
are in communication.

Next, when the push rod 4 is pushed, the piston 5 resists the return spring 16 and moves into the hydraulic chamber 6.
Move forward while shrinking.

At this time, the valve stem 19 remains as it is due to the biasing force of the valve spring 21, and the spherical valve head 23 seats on the valve seat 25 due to the advance of the piston 5, and the communication hole 15 is closed, and the valve stem 19 is connected to the hydraulic chamber 6. Communication with the oil supply chamber 9 is cut off.

When the piston 5 moves further forward, the valve stem 19 moves forward together with the piston 5 while the spherical valve head 23 remains seated on the valve seat 25, and the hydraulic chamber 6
generates pressure fluid.

Also, when the push rod 4 is released,
The piston 5, which is pushed back by the elastic force of the return spring 16, is restricted from retracting by the head of the push rod 4, and the valve stem 19 and the circlip 20 are locked to the retainer 17, and the spherical valve head 23 is held against the valve seat. The hydraulic chamber 6 and the oil supply chamber 9 communicate with each other through the through hole 13 , the communication hole 15 , the valve hole 14 , and the oil groove 22 , which are spaced apart from the oil supply chamber 25 .

Spherical valve head 2 sitting on valve seat 25 during the above operation
3, the roundness, roughness, and dimensional accuracy of the metal ball 24 can be processed well, so unlike the conventional rubber ball, it does not get caught in the valve seat and has excellent sealing performance.

In addition, because it has much greater durability than rubber valve discs, there is little deterioration even after repeated operation over a long period of time, especially when the valve disc is released from operation due to high hydraulic pressure. Suitable as a lock brake master cylinder.

Note that the spherical valve head of the present invention is not limited to the molded metal ball shown in the above embodiment, but may be integrally molded with the valve stem using synthetic resin or the like.

[Effect of idea]

As explained above, in the present invention, the communication hole for supplying the hydraulic fluid to the hydraulic pressure chamber is closed by the spherical valve head protruding from one end of the valve stem, so the spherical valve seated on the valve seat The head can be machined to have good roundness, roughness, and dimensional accuracy, so it does not get caught in the valve seat like conventional rubber ones, has excellent sealing performance, and ensures reliable operation over a long period of time. You can do it by holding it.

Furthermore, since it is easy to manufacture and has excellent installation properties, it is possible to reduce costs.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a sectional front view of a hydraulic master cylinder, and Fig. 2 is a perspective view of a valve stem. DESCRIPTION OF SYMBOLS 1... Hydraulic pressure master cylinder, 2... Cylinder body, 3... Cylinder hole, 4... Push rod, 5... Piston, 6... Hydraulic pressure chamber, 9... Oil supply chamber, 13... Through hole, 14 ... Valve hole, 15 ... Communication hole, 16 ... Return spring, 17, 18
...Retainer, 19...Valve stem, 19a...
...Shaft portion, 19b... Head, 20... Circlip, 21... Valve spring, 22... Oil groove, 23... Spherical valve head, 24... Metal ball such as steel ball, 25... Valve seat.

Claims (1)

[Scope of utility model registration request] It is equipped with a hydraulic pressure chamber defined in the cylinder hole by inserting the piston, and a communication hole for supplying working fluid to the hydraulic pressure chamber, and when the piston moves forward, the communication hole is closed by the valve body supported by the valve stem. A center valve type vehicle hydraulic master cylinder that generates pressure fluid in a hydraulic pressure chamber, characterized in that a spherical valve head serving as a valve body is formed protrudingly at one end of the valve stem. Hydraulic master cylinder for vehicles.