JPH0443411Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a master cylinder, and particularly to a master cylinder of the type in which a sealing mechanism is fixed to the inner periphery of the cylinder body and a piston slides on the inner periphery of the sealing mechanism. Regarding the cylinder.

[Prior Art] A piston sealing mechanism in a conventional master cylinder will be described with reference to FIG. First, to explain the overall structure of the master cylinder, in the same figure, 2 is a cylinder body, and a first return spring 4, a secondary piston 6, a second return spring 8, The primary pistons 10 are inserted one after another, forming a first liquid chamber 12 on the left side of the secondary piston 6 and a second liquid chamber 14 between the secondary piston 6 and the primary piston 10.

A guide pin 16 is fixed to the primary piston 10, and is loosely fitted into a guide hole 20 formed in a retainer 18 that is in contact with the secondary piston 6.

22 is a return port formed between a first input port 24 connected to a reservoir tank (not shown) and the first liquid chamber 12, and 26 is a second return port connected to a reservoir tank (not shown). Input port 28
This is a return port formed between the liquid passage 30 communicating with the second liquid chamber 14.

32 and 34 are cup seals for sealing the sliding surface between the secondary piston 6 and the inner periphery of the cylinder body 2, and 36 is a cup seal for sealing the sliding surface between the primary piston 10 and the inner periphery of the cylinder body 2. be.

Furthermore, a bush 3 that slidably supports the primary piston 10 is provided in the opening of the cylinder body 2.
8, and the bush 38 is sandwiched between a retaining member 40 and a pressing member 42 and fixed to the cylinder body 2 side.

44 is the bush 38 and the primary piston 10
cup seal for sealing the sliding surface of 46
An O-ring is installed in a groove formed in the inner periphery of the opening of the cylinder body 2 to seal between the cylinder body 2 and the bush 38.

Then, the primary piston 10 and the secondary piston 6 move forward into the cylinder hole in response to the operating force of the brake, and from when the cup seal 32 exceeds the first return port 22, the first liquid chamber 12
Similarly, from the time when the cup seal 36 exceeds the second return port 26, the hydraulic pressure in the second fluid chamber 16 increases, thereby controlling the brake fluid pressure to the wheels.

[Problems to be solved by the invention] However, in the conventional sealing mechanism for supporting and sealing the primary piston at the open end of the cylinder body, an O-ring is required to seal the contact surface between the bush and the cylinder body. Since the structure is such that it is inserted into a groove formed on the inner periphery of the cylinder body, there is a problem in that the manufacturing process for forming this groove becomes complicated.

In addition, in view of such problems, as shown in FIG. 6, by installing the O-ring 46 in the groove 48 formed on the outer periphery of the bushing 38, the groove for installing the O-ring shown in FIG. If the structure is such that it does not need to be formed on the cylinder body side, when the bushing 38 made of synthetic resin is molded using the split molding method, an axial parting line will remain on the sealing surface, and it will be difficult to remove this parting line. Since post-processing is required, a problem arises that does not contribute to the simplification of the manufacturing process.

[Means for Solving the Problems] The present invention has been made in view of the above problems, and its purpose is to provide a master cylinder equipped with a sealing mechanism that can simplify assembly. .

In order to achieve such an object, the present invention provides a master cylinder in which a primary piston is slidably supported on a bush provided at the open end of the cylinder body. A sealing member for sealing between the opening end of the body and the primary piston is installed in a space formed on the inner circumference of the bushing, and a sealing member for sealing between the bushing and the primary piston is installed. The present invention is characterized in that a seal pressing member for preventing these seal members from coming off is arranged at the stepped portion, and further a sealing mechanism is formed as a subassembly by fixing the seal pressing member to the stepped portion by press-fitting or caulking. The structure is such that the seal mechanism is assembled when assembling the master cylinder.

[Operation] A master cylinder equipped with such a sealing mechanism does not require the formation of a groove and recess processing for mounting an O-ring.

Furthermore, by configuring the sealing mechanism as a subassembly, it is possible to eliminate the conventional effort of assembling the entire master cylinder one by one.

[Example] Hereinafter, an example of the present invention will be described based on FIG. 1. First, to explain the structure, in FIG. 1, 2 is a cylinder body, and a first return spring 4, a secondary piston 6, a second return spring 8, and a primary piston 10 are installed in a cylinder hole formed in the longitudinal direction. The first liquid chamber 1 is inserted sequentially to the left side of the secondary piston 6.
2. A second liquid chamber 14 is formed between the secondary piston 6 and the primary piston 10.

A guide pin 16 is fixed to the primary piston 10, and is loosely fitted into a guide hole 20 formed in a retainer 18 that is in contact with the secondary piston 6.

22 is a return port formed between a first input port 24 connected to a reservoir tank (not shown) and the first liquid chamber 12, and 26 is a second return port connected to a reservoir tank (not shown). Input port 28
This is a return port formed between the liquid chamber 14 and the second liquid chamber 14.

32 and 34 are cup seals for sealing the sliding surface between the secondary piston 6 and the inner periphery of the cylinder body 2, and 36 is a cup seal for sealing the sliding surface between the primary piston 10 and the inner periphery of the cylinder body 2. be.

Furthermore, the stepped portion at the open end of the cylinder body 2 has a
A seal mechanism 50 is installed to slidably support the primary piston 10 and to seal between the inner periphery of the opening of the cylinder body 2 and the primary piston 10, and is fixed with a retaining member 40. That is, a resin-molded cap-shaped bush 52 is provided between the inner periphery of the cylinder body 2 and the primary piston 10, and the primary piston 10 and the bush 52 are slidably inserted into the inner periphery of the bush 52. Cup seal 54 for sealing the sliding surface and cylinder body 2
An O-ring 56 for sealing between the inner periphery of the opening end of the bushing 52 and the bushing 52 is fixed by a seal pressing member 58 so as not to come off.

The structure of the sealing mechanism 50 will be further described in detail based on FIGS. 2 to 4. As shown in FIG. a hole 60, a stepped portion 62 to which the retaining member 40 engages when installed, and a cylindrical stepped portion 6 to which the O-ring 56 is attached.
4. Furthermore, a space (not shown) for mounting the cup seal 54 inside is formed.

Then, the O-ring 56 is attached to the cylindrical stepped portion 64 as shown above.
Insert the cup seals 54 in between, and
By press-fitting a cap-shaped seal pressing member 58 as shown in Figure B into the cylindrical stepped portion 64,
A sealing mechanism 50 as a subassembly as shown in FIGS. 3 and 4 is formed. still,
FIG. 3 shows the sealing mechanism 50 held by the sealing member 58.
FIG. 4 is a perspective view of the sealing mechanism 50 seen from the step portion 62 side.

Further, as shown in FIG. 2C, by caulking and fixing a plate member 68 in which a hole 66 into which the primary piston 10 is inserted is formed in advance to the cylindrical stepped portion 64 of the bushing 52, the structure shown in FIG. A seal pressing member 58 may also be formed. It goes without saying that the seal pressing member 58 shown in FIG. 2C also has a hole (not shown) formed in advance into which the primary piston 10 is inserted.

The sealing mechanism 50 as such a subassembly is formed in advance and assembled to the open end of the cylinder body 2 when assembling the master cylinder.

In the master cylinder having such a structure, the primary piston 10 and the secondary piston 6 move forward into the cylinder hole in response to the operating force of the brake, and when the cup seal 32 exceeds the first return port 22, the first liquid chamber 12 is opened. Similarly, from the time when the cup seal 36 exceeds the second return port 26, the hydraulic pressure in the second fluid chamber 16 increases, thereby controlling the brake fluid pressure to the wheels.

[Effects of the Invention] As explained above, according to the present invention, the formation of a groove for mounting an O-ring for sealing and recess processing are not necessary, so that the assembly process can be simplified.

Furthermore, by configuring the seal mechanism as a subassembly, it is possible to eliminate the conventional effort of assembling each part one by one to assemble the entire master cylinder, thereby greatly simplifying the assembly process. I can do it.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing the structure of an embodiment of the present invention, Figs. 2 to 4 are perspective views for explaining the structure of the sealing mechanism in the embodiment, and Fig. 5 shows the structure of a conventional example. The sectional view and FIG. 6 are explanatory diagrams showing a conventional bushing taken out. Codes in the diagram: 2...Cylinder body, 10...
Primary piston, 50... Seal mechanism, 52
...Butsuyu, 54...Katsupushir, 56...
O-ring, 58... Seal pressing member, 60...
Hole, 62... step, 64... cylindrical step, 66...
Hole, 68...Plate member.

Claims (1)

[Claims for Utility Model Registration] In a master cylinder in which a primary piston is slidably supported on a bush provided at an open end of a cylinder body, a stepped portion formed on the outer circumferential side of the bush is provided with an opening between the bush and the cylinder body. A sealing member for sealing between the bushing and the primary piston is installed in a gap formed on the inner circumference of the bushing, and A seal holding member for preventing these sealing members from coming off is disposed in the bushing, and the seal holding member is fixed to the stepped portion of the bush by press-fitting or caulking to form a seal structure, thereby forming a subassembly. master cylinder.