JPH0228134Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of a master cylinder for a clutch or a brake installed in an automobile or the like.

[Conventional technology and problems]

As shown in Japanese Utility Model Application Publication No. 58-22366, conventionally, this type of master cylinder has a cylinder body with a cylinder hole with one end open, and a cylinder body with a cylinder hole that is slidably inserted into the cylinder hole. a piston forming a hydraulic pressure chamber between the piston and the closed end; a groove-shaped elongated hole provided in an intermediate portion of the piston and extending in the axial direction; A through hole communicating with the hydraulic pressure chamber;
a valve device disposed facing the hydraulic pressure chamber side opening of the through hole and capable of blocking liquid movement from the hydraulic pressure chamber to the through hole; and a valve device attached to the cylinder body and having one end fitted into the elongated hole. A master cylinder is known that includes a shaft member which is movably fitted into the through hole and whose one end can come into contact with the shaft member to open the valve device.

In the master cylinder described above, a stopper is provided at the opening of the cylinder body in order to restrict the backward movement position of the piston.

In such a master cylinder, when the piston is made of a synthetic resin material,
The piston deforms due to repeated stress and thermal history, and the overall length of the piston changes.

However, as mentioned above, when the return position of the piston is regulated by bringing the piston into contact with a stopper provided at the opening of the cylinder body, if the overall length of the piston changes, the distance between the valve seat and the valve member at the return position will change. The problem has been that the valve closing timing becomes earlier or later, and the idle stroke becomes shorter or longer.

[Purpose and structure of the invention]

An object of the present invention is to provide a master cylinder that improves the conventional master cylinder described above, reduces the axial length of the master cylinder, and reduces the number of parts. According to the present invention, in the above structure, the shaft member has a large protrusion that can come into contact with the piston, and a small protrusion that is provided integrally with the large protrusion and can come into contact with the valve driving member. The large protrusion comes into contact with the hydraulic chamber side end surface of the elongated hole of the piston in the return position of the piston, and the small protrusion comes into contact with a master cylinder that abuts the valve drive member, respectively. It is achieved by doing so.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In the figure, the master cylinder is indicated as a whole by 1, and a reservoir 3 is fixed to a boss portion 2a of a cylinder body 2. The cylinder body 2 has a cylinder hole 4 with one end open, into which a piston 5 made of synthetic resin is slidably fitted. piston 5
is urged rightward by a spring 6, and its return position is regulated by a stopper bolt 19, which will be described in detail later.

A hydraulic pressure generating chamber 7 is defined within the cylinder hole 4 between the piston 5 and the closed end, and a push rod 9 is engaged in a recess 8 at the outer end of the piston 5.

Both ends 10 and 11 of the piston 5 have large diameters and are in sliding contact with the inner circumferential surface of the cylinder hole 4. That is, it functions as a sliding portion of the main piston 5. These sliding parts 10 and 11 are seal members 12 and 13, respectively.
is installed, and the above-mentioned hydraulic pressure generation chamber 7 and sliding parts 10 and 1 are installed.
A liquid supply chamber A is defined between the two. The liquid replenishment chamber A is always in communication with the inside of the reservoir 3 via a replenishment hole 2c formed in the cylinder body 2.

Intermediate portion 14 between sliding portions 10 and 11 of piston 5
A groove-like elongated hole 15 extending in the axial direction and having a cross-sectional shape as shown in FIG. The upper and lower parts of the piston 5 are freely communicated by the long hole 15 and the short hole 16, and the annular gap a between the piston 5 and the inner peripheral surface of the cylinder hole 4, and the long hole 1
5. The short hole 16 constitutes the above-mentioned liquid supply chamber A.

Further, a cylinder hole 16 is provided in the center of the intermediate portion 14.
The radial protrusion 17a, 1 is in sliding contact with the inner circumferential surface of the
7b, 18a, and 18b are formed. That is, these constitute the third sliding section. The above-mentioned first and second vibrating parts 10 and 11 of the piston 5 have a cross-sectional shape as shown in FIG. 3, but their left and right ends 11a and 11b are flat. That is, in this embodiment, the piston 5 is molded, but due to the separation of the upper mold and the lower mold, a parting line is created in the center of the left and right ends 11a, 11b of the piston 5 in FIG. (not shown). That is, although burrs are formed, they do not form a sliding surface in flat molding as shown in the figure, so there is no problem if they are left. As shown in FIG. 4, the intermediate portion 14 is formed by further deep plane molding to form a larger gap between the planes 14a and 14b and the inner peripheral surface of the cylinder hole 4, thereby improving the flow of liquid. It makes the resistance smaller. Note that since the piston 5 is formed by molding, there are draft angles at various places, for example, the elongated hole 15 has surfaces 15a, 15b, 15.
A draft angle as shown in FIGS. 15c and 15d is formed.

A stopper bolt 19 according to the present invention is screwed onto a protruding portion 2b of the lower wall portion of the cylinder body 2 with a seal ring 20 interposed therebetween. In the part inserted into the cylinder hole 4 (fitted into the elongated hole 15 of the intermediate part 14 of the piston 5 as shown in FIG. 5), the large diameter part 21 and the tapered part 22
and a small diameter portion 23, and the large diameter portion 21 is in contact with the sliding portion 10 provided with the surface 15c of the elongated hole 15 of the piston 5. Since the inclination of the tapered portion 22 is opposite to the draft angle of the surface 15c of the elongated hole 15, a considerable gap is formed between them.

A through hole 24 is formed in the sliding part 10 in the axial direction,
A valve drive rod 28 is inserted through this, and when the piston is in the normal return position shown in the figure, one end thereof is in contact with the small diameter portion 23 of the stopper bolt 19 mentioned above, and the valve member 25 is at the other end. Fixed. The valve member 25 is biased to the right by a valve spring 27 stretched between the spring receiver 26 and the spring receiver 26.
It is slidable into the center hole at the bottom of the piston 6, and is spaced from the valve seat 10a formed on the end surface of the sliding portion 10 of the piston 5 in the normal illustrated state. That is, the valve device consisting of the valve member 25, the spring receiver 26, and the valve spring 27 is open, and the fluid pressure generation chamber 7 is communicated with the fluid supply chamber A. As described above, in the master cylinder 1 of the present invention, the stopper bolt 19, which is a shaft member inserted into the cylinder hole 4, is inserted into the cylinder hole 4 as shown in the figure.
The large diameter portion 21 of the long hole 15 formed in the piston 5
The return position is regulated by contacting the surface 15c on the hydraulic pressure generating chamber 7 side. The spring receiver 26 has a tip shape and is fitted to the tip of the sliding portion 10 of the piston 5, and the above-mentioned spring 6 is stretched between this and the closed end of the cylinder hole 4.
Further, a plurality of openings 26 are provided in the peripheral wall of the spring receiver 26.
a is formed. Although not shown, the hydraulic pressure generation chamber 6
communicates with the wheel cylinder through a connection hole formed in the cylinder body 2.

The embodiment of the present invention is configured as described above,
Next, this action, effect, etc. will be explained.

When a brake pedal (not shown) is stepped on, a push rod 9 causes the piston 5 to slide inside the cylinder hole 4 to the left in FIG. Sliding part 10
As the valve member 25 moves forward, it seats on the valve seat 10a. Thereafter, the liquid flow from the liquid supply chamber A to the liquid pressure generation chamber 7 is allowed, but the liquid flow in the opposite direction is blocked.

After the valve member 25 is seated on the valve seat 10a, the piston 5 moves and the hydraulic pressure in the hydraulic pressure generating chamber 7 increases, thereby applying brakes to the wheels. When the pressure on the brake pedal is released to release the brake, the piston 5 moves to the right in FIG. 1 due to the spring force of the spring 6. When the inside of the hydraulic pressure generating chamber 7 becomes negative pressure with this movement, the valve member 25 is opened and the hydraulic fluid flows into the hydraulic pressure generating chamber 7 from the liquid replenishing chamber A. Therefore, the piston 5 quickly moves to the right,
The sliding portion 10 having the surface 15c of the elongated hole 15 comes into contact with the large diameter portion 21 of the stopper bolt 19.
Further, the valve drive rod 28 comes into contact with the small diameter portion 23. This causes the piston 5 to stop at the regulated position. Further, the valve member 25 is moved away from the valve seat 10a. Note that a considerable gap is formed between the tapered portion 22, the small diameter portion 23, and the sliding portion 10 of the stopper bolt 19 even when the large diameter portion 21 is in contact with the fluid pressure generating chamber 7. This makes it easy to supply liquid to and from the supply chamber A.

This embodiment has the above-mentioned functions and effects, but also has the following effects.

That is, since the return position of the piston 5 is restricted by the stopper bolt 19, the axial length of the master cylinder 1 can be shortened.
That is, conventionally, the open end side of the cylinder body 2 was further lengthened, a stopper was provided there, and the rear end of the piston was brought into contact with this stopper to restrict the return position. However, according to this embodiment, such a stopper can be omitted, and the cylinder body extension for attaching this stopper can be omitted. Therefore, the axial length of the master cylinder 1 can be reduced. Furthermore, the number of parts can be reduced compared to the conventional method.

In addition, in this embodiment, the third sliding parts 17a, 17b, 18a, and 18b are formed in the intermediate part 14 of the piston 5, so that the piston 5 made of synthetic resin is prevented from being significantly deformed during brake operation. be done. That is, during brake operation, the piston 5 receives a mechanical pressing force from the bushing rod 9 and a hydraulic pressure from the hydraulic pressure generating chamber 7, and a large force is applied to the piston 5 in the compression direction. However, the third sliding portion 17
a, 17b, 18a, and 18b prevent the intermediate portion 14 from being significantly deformed into a drum shape due to this force. Conventionally, since the third sliding part was not provided, there was a risk of large deformation in the shape of a drum, resulting in permanent deformation or cracking, but according to the present embodiment, this fear can be eliminated.

In addition, in this embodiment, even if the total length of the piston 5, which is made of synthetic resin, changes due to repeated stress or thermal history, the elongated hole from the valve seat 10a is adjusted to the amount of change in the total length. 15 to the surface 15c is small. Therefore, piston 5
In the return position, the distance between the valve member 25 and the valve seat 10a is substantially the same as in the original state, and the closing timing and idle stroke length of the valve device when the master cylinder is operated hardly change.

Also, due to the compressive force, the third sliding portions 17a, 17
b, 18a, 18b are pressed against the inner circumferential surface of the cylinder hole 4, and the amount of wear due to sliding in this state is greater than that in other parts, but since the wall thickness is larger in this part, Since the parts do not require any sealing properties, some wear is not a problem. Conventionally, when the piston is deformed into a drum shape, it wears intensively only at the top of the deformation, which causes abnormal uneven wear and shortens the life of the piston, but in this embodiment, the third sliding portions 17a, 17b, 18a,
18b also acts as a reinforcing material and not only withstands some wear, but as can be seen with reference to FIG. 4, when compressive force is applied, the left and right flesh portions of the elongated hole 15 tend to expand to the left and right. This increases the resistance to this deformation.

Although the embodiments of the present invention have been described above, the present invention is of course not limited thereto, and various modifications can be made based on the technical idea of the present invention.

For example, in the above embodiment, the third sliding portion 17a,
17b, 18a, 18b are the short hole 16 and the flat part 1
It was divided into four parts for 4a and 14b, but the short hole 16
Alternatively, the flat parts 14a and 14b may be omitted to form an integrated sliding part.

Further, in the above embodiment, the intermediate portion 1 of the piston 5
A third sliding part was provided at one location in 4, but multiple locations were provided.
It may also be provided.

For example, in the above embodiment, the stopper bolt 19 has a large diameter portion 21, a tapered portion 22, and a small diameter portion 23, but the tapered portion 22 is omitted and the small diameter portion 23 is further extended to the large diameter portion 21. It may also be an extended configuration. That is, it may have a stepped shape.

Further, in the above embodiment, the valve drive rod 28 is integrated with the valve member 25, but it is formed separately and fitted into the through hole 24 of the sliding portion 10 to facilitate liquid flow. A plurality of grooves may be formed on the outer circumference in the axial direction.

[Effect of idea]

As described above, according to the master cylinder of the present invention, the stopper bolt 19 as a shaft member has a large diameter portion 21 as a large protrusion that can come into contact with the piston.
and a small protrusion that is provided integrally with the large protrusion and can come into contact with the valve drive rod as the valve drive member, so the stopper that was conventionally provided at the open end of the cylinder body is omitted. Therefore, the axial length of the master cylinder can be shortened and the number of parts can be reduced. Moreover, a sufficient liquid passage can be secured when the valve device is opened.

Furthermore, according to the master cylinder of the present invention, even if the total length of the piston changes due to repeated stress or thermal history, the distance between the valve member and the valve seat remains at the original position when the piston returns to its position. is almost the same as
The valve closing timing and idle stroke length of the valve device during operation of the master cylinder hardly change and can be kept almost constant.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a master cylinder according to an embodiment of the present invention, FIG. 2 is a side sectional view of a piston in the same master cylinder, FIG. 3 is a sectional view along the - line in FIG. - in figure 2
A sectional view in the line direction, and FIG. 5 is a sectional view in the - line direction in FIG. 1. In the figure, 1...master cylinder, 2...
... Cylinder body, 4 ... Cylinder hole, 5 ... Piston, 19 ... Stopper bolt, 21 ... Large diameter part, 23 ... Small diameter part, 25 ... Valve member, 28 ...
Valve driven rod.

Claims (1)

[Scope of utility model registration request] A cylinder body formed with a cylinder hole with one end open, a piston made of a synthetic resin material that is slidably inserted into the cylinder hole and forms a hydraulic chamber between the closed end of the cylinder hole, and an intermediate portion of the piston. a groove-shaped elongated hole provided in the piston and extending in the axial direction; a through hole provided in the hydraulic pressure chamber side portion of the piston and communicating the elongated hole with the hydraulic pressure chamber; and a through hole on the hydraulic pressure chamber side of the piston. A valve device comprising a valve seat formed around an opening and a valve member biased toward the valve seat by a valve spring, and capable of preventing liquid movement from the hydraulic pressure chamber to the through hole. a shaft member attached to the cylinder body and having one end fitted into the elongated hole; and a valve drive movably fitted into the through hole and one end capable of abutting against the shaft member to open the valve device. In the master cylinder, the shaft member includes a large protrusion that can abut the piston, and a small protrusion that is provided integrally with the large protrusion and that can abut the valve drive member. have,
The large protrusion is in contact with the hydraulic chamber side end surface of the elongated hole of the piston in the return position of the piston, and the small protrusions are in contact with the valve drive member, respectively.