JP2579879Y2 - Master cylinder - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a master cylinder.

[0002]

2. Description of the Related Art A master cylinder employed in a brake device operates a piston by depressing a brake pedal, and the piston causes liquid in a pressure chamber to be pumped to a wheel cylinder. When the depression force of the brake pedal is released, the piston is returned to the original position by the urging force of the return spring.

[0003]

However, in such a master cylinder, as shown in FIG. 3, when the master cylinder is removed from the booster, the piston 34 is moved by the biasing force of the return spring 33. A retainer 35 is provided so as not to protrude from the cylinder.

The retainer 35 is composed of a cylindrical portion 35a and a columnar portion 35b, which are telescopically fitted and provided with a stopper 35c on the columnar portion 35b so that they do not come off from each other. ing. Further, flanges 35d and 35e are formed at ends of the cylindrical portion 35a and the columnar portion 35b, and a return spring 33 is interposed between the flanges 35d and 35e. Therefore, the return spring 33 is
The retainer 35 defines its maximum extension and does not unnecessarily affect the piston 34.

[0005] However, the structure of such a retainer 35 is complicated, which not only increases the parts manufacturing cost but also complicates the assembling work.

The piston guide 36 is provided with a cup packing 37 for sealing between the piston guide 36 and the piston 34. The cup packing 37 is formed by a piston guide 36 and an annular projection 31 a formed inside the body 31.
Held in that position.

However, the projection 31a is formed at the same time as the body 31 and the step 31b for positioning the piston guide 36 is formed by machining. Therefore, the distance between the projection 13a and the step portion 31b varies, and the cup packing 37 accommodated between them may not always be accommodated in an optimal state.

Therefore, the purpose of the present invention is to use inexpensive parts,
It is another object of the present invention to provide a master cylinder which can be easily assembled and can keep the packing in an optimum state.

[0009]

In the master cylinder of the present invention, a piston guide is fitted into a cylinder hole, packing is attached to the piston guide, a pressure chamber is defined in the cylinder hole, and the piston An annular groove is formed on the peripheral surface of the cylinder hole in a master cylinder in which a piston is inserted into a guide and packing, and a return spring is disposed in the pressure chamber to urge the piston outward of the pressure chamber. The piston has a ring-shaped stopper having a protrusion protruding radially outward at the tip of the piston and having a claw protruding radially outward at one end, and the claw of the stopper is provided in the annular groove of the cylinder hole. The stopper is disposed in the cylinder hole with the other end of the stopper facing the end face of the packing. By contact with projections, which restricts the movement of the omission direction of the piston.

[0010]

In the master cylinder according to the present invention, the piston is prevented from popping out by one stopper, and the cup packing is housed between the stopper and the piston guide to hold the cup packing. Interval accuracy is secured.

[0011]

1 shows a master cylinder according to the present invention, and FIG. 2 is an exploded view of a main part thereof.

In this master cylinder, a cylinder housing 1 is constituted by a body 2 and a cap 3. The cylinder hole 4 is formed over the body main body 2 and the cap 3. Piston guides 5 and 6 are provided in the cylinder hole 4 so as to sandwich the sleeve 7. A primary piston 8 and a secondary piston 9 are inserted through these piston guides 5 and 6, respectively. The pistons 8 and 9 divide the inside of the cylinder hole 4 into a first pressure chamber 10 and a second pressure chamber 11. Has been established. Further, a cup packing 1 is provided on the piston guides 5 and 6.
2 and 13 are respectively provided, and the space between the piston guides 5 and 6 and the pistons 8 and 9 is sealed by the cup packings 12 and 13. First pressure chamber 10
The second pressure chamber 11 and the second pressure chamber 11 are respectively formed with outlets 14 and 15, and the outlets 14 and 15 are connected to wheel cylinders and the like of each brake system.

A retainer 16 is provided between the primary piston 8 and the secondary piston 9 so as to be able to expand and contract. The retainer 16 has a hat-shaped portion 16.
a and a cylindrical portion 16b, which are fitted telescopically and provided with a stopper 16c on the cylindrical portion 16b so that they do not come off from each other.
Further, flanges 16d and 16e are formed at ends of the hat-shaped portion 16a and the cylindrical portion 16b, and a return spring 17 is interposed between the flanges 16d and 16e. Therefore, the maximum extension of the return spring 17 is defined by the retainer 16.

An annular groove 18 is formed in the peripheral wall of the second pressure chamber 11. A stopper 19 is locked in the annular groove 18.

The stopper 19 is integrally formed of, for example, a synthetic resin, and as shown in FIG.
9a and a leg 19b projecting from the cylindrical portion 19a. The cylindrical portion 19a has a hole 19c through which the secondary piston 9 is inserted. Leg 19
b has a claw 19d protruding outward in the radial direction at the end. The stopper 19 is inserted into the cylinder hole 4 in a state where the leg 19b is bent inward in the radial direction. When the stopper 19 is advanced in the cylinder hole 4 and the claw 19d reaches the annular groove 18, the leg portion 19b is expanded outward in the radial direction, and the claw 19d protrudes into the annular groove 18 and the annular groove 19b. Engages.

As shown in FIG. 1, the stopper 19 mounted in the cylinder hole 4 has an end 19e reaching the vicinity of the cup packing 13, and the end 19e moves the cup packing 19 there. Let it be maintained.

The secondary piston 9 is inserted into the hole 19c of the stopper 19, as shown in FIG. Then, a return spring 20 is interposed between the secondary piston 9 and the end wall 4a of the cylinder hole 4.

The stopper 19 has a step 19f, and the secondary piston 9 has a projection 9a projecting outward in the radial direction at the tip. And
When the piston 9 is moved in the direction of the primary piston 8 by the biasing force of the return spring 20, the projection 9a comes into contact with the step 19f, and further movement is restricted.

The stopper 19 includes means for engaging the annular groove 18 of the cylinder hole 4, means for maintaining the cup packing 13 therein, and the secondary piston 9.
The shape and the like are not limited to those in the above-described embodiment as long as they have a means for restricting the movement of a predetermined amount or more.

[0020]

[Effects of the Invention] As described above, the master cylinder according to the present invention does not require a retainer having a complicated structure, and can be used as one cylinder.
The two stoppers prevent the piston from popping out,
Moreover, the packing is held between the stopper and the piston guide.

Therefore, parts can be obtained at a low cost, the assembly is simple, and the packing can always be maintained in an optimum state.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a master cylinder according to the present invention.

FIG. 2 is an exploded perspective view showing a main part of FIG.

FIG. 3 is a sectional view showing a conventional master cylinder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder housing 2 Body main body 3 Cap 4 Cylinder hole 6 Piston guide 9 Secondary piston 9a Projection 11 Second pressure chamber 13 Cup packing 18 Annular groove 19 Stopper 19a Cylindrical portion 19b Leg 19c Hole 19d Claw 19e End 19f Step 20 Return spring

Claims (1)

(57) [Scope of request for utility model registration] 1. A piston guide is fitted in a cylinder hole, a packing is attached to the piston guide, a pressure chamber is defined in the cylinder hole, and a piston is fitted in the piston guide and the packing. In a master cylinder in which a return spring is disposed in the pressure chamber and the piston is urged outward from the pressure chamber, an annular groove is formed on the peripheral surface of the cylinder hole, and a radially outward groove is formed at the tip of the piston. And an annular stopper having a claw projecting outward in the radial direction at one end, the claw of the stopper being engaged with the annular groove of the cylinder hole, and the other end of the stopper being The stopper is disposed in the cylinder hole so as to face the end face of the packing, and the protrusion of the piston is brought into contact with the stopper, so that the A master cylinder whose movement is restricted.