JPH081998Y2 - Master cylinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application The present invention relates to a master cylinder, and more particularly to the structure of a cylinder housing.

b. Conventional Technique FIG. 4 shows a master cylinder that has been conventionally employed.

In this master cylinder 1, the cylinder housing 2
Is composed of the body 3 and the cap 4. The body 3 has an opening 3a at one end, and a female screw 3b is formed on the inner peripheral surface of the opening 3a. On the other hand, a male screw 4a is formed on the outer peripheral surface of one end of the cap 4, and the cap 4 is formed by screwing the male screw 4a into the female screw 3b of the body 3.
Be attached to.

In this master cylinder 1, a gasket 5 is interposed between the body 3 and the cap 4 in the opening 3a of the body 3 to seal them.

c. Problems to be Solved by the Invention In the master cylinder 1, the cap 4 has the piston 6 fitted therein, and the piston 6 is guided by the sleeve 7 positioned inside the body body 3. On the other hand, a piston guide 8 having an oil passage 8a is positioned in the cap 4. The piston 6 is also inserted through the piston guide 8.
The gap between the piston guide 8 and the piston 6 is sealed by a packing 9 attached to the piston guide 8. The oil in the oil reservoir 10 is
Is supplied to the pressure chamber 12 in the cylinder housing 2 through a passage 11 formed between the cylinder 4 and the cap 4, a passage 8a of the piston guide 8 and a passage 6a formed in the side wall of the piston 6. When the piston 6 moves leftward and the passage 6a of the piston 6 reaches the packing 9 attached to the piston guide 8, the pressure chamber 12 is shut off from the oil reservoir 10, and the piston 6 moves leftward thereafter. The oil in the pressure chamber 12 is pumped to a wheel cylinder (not shown).

In the master cylinder 1, in order to prevent the packing 9 from being bitten into the gap between the piston 6 and the piston guide 8 by the pressure in the pressure chamber 12, the gap between the sliding portions of the piston guide 8 and the piston 6 is set to the maximum. I have made it small.

Therefore, in such a master cylinder 1, the piston 6 is guided by the sleeve 7 on the body body 3 side and the piston guide 8 on the cap 4 side, and the axes of the sleeve 7 and the piston guide 8 must be aligned. The operation of the piston 6 becomes heavy.

However, in the conventional master cylinder 1 described above, the cap 4 is simply screwed into the body body 3,
The backlash between the screws 4a and 3b may cause the axial center of the cap 4 to shift with respect to the body body 3.

Therefore, an object of the present invention is to provide a master cylinder in which the cap can be attached to the body body without causing misalignment.

d. Means for Solving the Problems In the master cylinder of the present invention, a cylinder housing is constituted by a body body having an opening at one end and a cap screwed into the body body to close the opening,
Further, in the master cylinder in which the piston is fitted into the cap, the cylinder portion is formed inward of the screwing portion of the body body with the cap, and the tip of the screwing portion with the body body of the cap is formed. An annular groove is formed on the outer peripheral surface, an O-ring is fitted into the groove, and the cap is screwed onto the body main body while slidingly contacting the O-ring with the cylinder portion.

e. Operation In the master cylinder of the present invention, the O-ring fitted to the cap guides the cap while slidingly contacting the cylinder portion of the body. Therefore, the cap is screwed in the body main body in a state where the axis of the cap matches the axis of the body main body, and is attached to the body main body. At that time, the O-ring is always held in place by the groove.

f. Embodiment FIG. 1 shows a master cylinder according to the present invention.

The cylinder housing 21 of the master cylinder 20 is composed of a body 22 and a cap 23. The body 22 has an opening 22a at one end. And
A female screw 22b is formed on the inner peripheral surface of the opening 22a, and a cylinder portion 22c is formed further inward. On the other hand, a male screw 23a is formed on the outer peripheral surface of the cap 23, and the outer diameter of the tip portion 23b of the male screw 23a is slightly smaller than the inner diameter of the cylinder portion 22c of the body body 22, Further, an annular groove 23c is formed on the outer peripheral surface of the tip portion 23b.

Then, as shown in FIG. 2, the cap 23 has an O-ring 24 fitted in its groove 23c, the male screw 23a of which is screwed into the female screw 22b of the body 22, and the cap 23 is advanced. . Then, as shown in FIG. 3, the O-ring 24 abuts on the cylinder portion 22c of the body body 22, slides along the screw movement of the cap 23, and guides the cap 23. At that time, a force in the direction of shifting the O-ring 24 due to sliding resistance acts on the O-ring 24, but
Since it is restrained in c, it does not fall off from the cap 23. In this way, the cap 23 is
Be attached to.

Inside this cylinder housing 21, the piston guide 2
5, the sleeve 26 and the piston guide 27 are arranged in contact with each other in series, and the piston guide 25 and the sleeve 26 are
The inner peripheral surface of the cap is centered on the piston guide 27, and the piston guide 27 is centered on the inner peripheral surface of the cap 23. Also, these piston guide 25, sleeve 2
6. The piston guide 27 is sandwiched between the body 22 and the cap 23, and the distance between the piston guides 25 and 27 is maintained constant. Then, the piston guide 25 and the sleeve 26
A piston 28 is inserted therethrough, and the piston is guided by their piston guide 25 and sleeve 26. Also, the sleeve 26 and piston guide 27
A piston 29 is inserted through them, and the piston 29 is guided by the sleeve 26 and the piston guide 27 thereof. The piston 29 is also inserted through the cap 23, and its end portion extends to the outside of the cylinder housing 21. The pistons 28, 29 are urged to the right in FIG. 1 by springs 30, 31 arranged between the body 22 and the piston 28 and between the pistons 28, 29.

Further, the inside of the cylinder housing 21 is divided into two pressure chambers 32, 33 by a piston guide 25 and a piston 28, and these pressure chambers 32, 33 are respectively formed in the pistons 28, 29.
Passages 28a, 29a formed in the peripheral wall of each piston guide 25,
The passages 25a and 27a formed in 27, the passages 34 and 35 formed in the cylinder housing 21, and the passages 36a and 36b formed in the bottom of the oil reservoir 36 communicate with the oil reservoir 36 and are also formed in the cylinder housing 21. The front and rear wheel cylinders (not shown) are communicated with each other via the ports 37 and 38.
Incidentally, in FIG. 1, reference numerals 39, 40 and 41 indicate packings.

This master cylinder 20 moves the piston 29 to the left in FIG. 1 by the force generated by stepping on the brake pedal, and the passage 27a of the piston guide 27 and the piston 2 are moved.
By disconnecting the communication with the passage 29a of 9 and further reducing the volume in the pressure chamber 33, the oil in the pressure chamber 33 is ported.
The pressure is sent from the wheel cylinder 38 to a wheel cylinder (not shown), the movement of the piston 29 is transmitted to the piston 28, and the piston 28 is moved to the left in FIG. 1 to establish communication between the passage 25a of the piston guide 25 and the passage 28a of the piston 28. By cutting off and further reducing the volume in the pressure chamber 32, the oil in the pressure chamber 32 is pumped from the port 37 to another wheel cylinder (not shown).

The cap 23 shown in the above embodiment is generally formed by die casting. Then, the groove 23c for loading the O-ring 24 is later processed by a lathe. By the way, since the die-cast product may have a cavity inside, the depth 1 of the groove 23c is preferably about 0.2 to 0.5 mm.

Further, the tip wall 23d of the groove 23c shown in the above-mentioned embodiment is not necessarily required to be continuous over the entire circumference, as long as it can prevent the O-ring 24 from falling off, and for example, at substantially equal intervals over the entire circumference, It may be formed at a plurality of locations.

g. Effect of the Invention As described above, in the master cylinder according to the present invention,
When the cap is attached to the body body, the O-ring is guided by the cylinder portion of the body body, and the cap is fastened to the body body while being centered with respect to the body body.

Therefore, the sleeve positioned on the body body and the piston guide positioned on the cap have their axes aligned with each other, and a smooth movement of the piston guided between the sleeve and the piston guide is ensured.

Further, in the master cylinder according to the present invention, since the O-ring is loaded in the annular groove, the O-ring does not come off from the cap when the cap is attached to the body and when the cap is removed from the body. There is no.

Therefore, in the state where the cap is mounted on the body main body, the sealing effect is ensured, and the work of removing the cap from the body main body becomes easy.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a master cylinder according to the present invention, and FIG.
FIG. 3 and FIG. 3 are enlarged cross-sectional views of an essential part showing a state when the cap is assembled to the body main body, and FIG. 4 is a vertical cross-sectional view showing a conventional master cylinder. 20 …… Master cylinder, 21 …… Cylinder housing, 22
…… Body body, 22a …… Opening, 22b …… Female screw, 22c…
… Cylinder part, 23 …… Cap, 23a …… Male screw, 23b…
… Tip, 23c …… annular groove, 24 …… O ring, 26 ……
Sleeve, 27 ... Piston guide, 27a ... Passage, 29 ...
... piston, 29a ... passage.

Claims (1)

[Scope of utility model registration request] 1. A master cylinder comprising a body body having an opening at one end, and a cap which is screwed into the body body to close the opening, and a piston is fitted in the cap. A cylinder portion is formed inward of the threaded portion of the body body with the cap, and an annular groove is formed on the outer peripheral surface of the tip of the threaded portion of the cap with the body body. A master cylinder, wherein an O-ring is fitted in the groove, and the O-ring is brought into contact with the cylinder portion.