JPH05170089A - Master cylinder - Google Patents

Abstract

PURPOSE:To enable the stamping work of a retainer and reduce the number of part items by engaging the claw part of the retainer, provided to lock a return spring disposed between the retainer and the bottom part of a cylinder body, with a groove formed at the inner peripheral surface of a recessed part formed at a piston, thus fixing the piston. CONSTITUTION:A second piston 4 is provided with a recessed part 4a opened toward the bottom part of a cylinder body 2 so as to be held by a second connecting rod 23 and a second return spring 8b provided between a third retainer 21 and a holder 22 fixed to the bottom part of the cylinder body 2. The third retainer 21 is provided with plural claw parts 27 and a through hole 28 formed at the bottom part 29 with which a valve spring 25 is brought into contact so as to be pierced with the second connecting rod 23. The tip 27a of the claw part 27 is engaged with a ring groove 30 formed at the inner peripheral surface of the recessed part 4a to regulate the movement of the piston 4 to the bottom part of the cylinder body 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a master cylinder used in a brake device, a clutch device, etc. of a vehicle, and more particularly to a master cylinder of a center valve type portless mechanism.

[0002]

2. Description of the Related Art Conventionally, as a technique of this kind, there is, for example, Japanese Utility Model Laid-Open No. 62-128972, which defines a pressure chamber communicating with a brake cylinder through an output port in a cylinder body. A piston that is slidably inserted and has a recess formed at the tip, a communication passage that connects the recess formed in the piston to the supply port that communicates with the reservoir, and a communication passage that is provided in the recess of the cylinder body. A valve that can be opened and closed, a connect-in groove that penetrates through a holder that is fixed at the bottom of the cylinder body that is formed integrally with the valve, and guides the movement of the connect-in groove and returns between the holder and A guide member is provided with a spring, in which a communication hole that communicates between the pressure chamber and the recess is formed, and is fitted in an annular groove formed on the outer periphery of the guide member. In the assembled state, there is provided a C ring that fits into a recess groove formed at a position facing an annular groove formed on the inner circumference of the piston and integrally connects the piston and the guide member. ..

[0003]

However, in the above-mentioned prior art, the guide member is formed on the piston, the rod sliding surface for guiding the connect rod, the fitting groove for fitting the C ring, and the piston. In addition, since the recess has a communication hole that communicates with the pressure chamber, the structure is complicated and the cost is increased. In addition, the guide member has to be cut, which is costly. Further, since the guide member and the piston are connected by the C ring, the C ring is required, and the number of parts is increased, resulting in cost increase.

Therefore, an object of the present invention is to simplify the structure.

[0005]

[Constitution of the invention]

[0006]

The technical means taken in the present invention to solve the above-mentioned technical problem is a hollow cylinder body and a slidable fitting insertion into the cylinder body. And a pressure chamber formed between the piston and the bottom of the cylinder body,
A replenishment chamber formed between the outer periphery of the piston and the cylinder body, a communication passage formed in the piston for communicating between the pressure chamber and the replenishment chamber, a holder having a through hole fixed to the bottom of the cylinder body, and a holder A connect rod that has a large diameter part that penetrates the through hole and has one end that fits into the recess, a valve that is formed at the end of the connect rod that can open and close the communication path, and a valve that connects the communication hole. In a master cylinder that includes a valve spring that biases once and a return spring that is arranged between a holder and a piston, a groove is formed in the inner peripheral surface of a recess formed in the piston, and the through hole is connected. A retainer that has a smaller diameter than the large diameter portion of the tie rod, has a claw portion protruding in the outer circumferential direction at a position facing the groove, and has one end of the valve spring disposed therein. Is that which is adapted and a Na.

[0007]

The above technical means works as follows. A retainer, which is arranged between the bottom of the cylinder body and a return spring, engages a retainer protruding in the outer peripheral direction with a groove formed in the inner peripheral surface of the recess formed in the piston. The retainer and piston can be fixed by.

By this action, the retainer can be press-molded and the number of parts can be reduced.

[0009]

Embodiments to which the present invention is applied will now be described in detail with reference to the accompanying drawings.

In FIG. 1, a master cylinder 1 is formed in a hollow cylindrical shape, a cylinder body 2 having a left end in the figure closed and a right end in the figure open, and a first pressure chamber 6 in the cylinder body 2.
And a first piston 3 and a second piston 4 which partition the second pressure chamber 7 and are slidably fitted therein.

A reservoir tank (not shown) for storing hydraulic oil is connected to the cylinder body 2 at the upper portion of the drawing by reservoir connecting portions 12 and 13. Also, the cylinder body 2
Is equipped with a seal 9 that holds the cylinder body 2 and the first piston 3 in a liquid-tight manner on the inner circumference of the opening, and a first replenishing chamber 10a is formed between the seal 9 and the supply port 2a. .. A small hole 11 that connects the supply port 2a and the first pressure chamber 6 is formed in the peripheral wall of the cylinder body 2 inward of the first supply chamber 10a. Therefore, the first pressure chamber 6 includes the supply port 2a and the small hole 11.
Through the reservoir tank.

The first piston 3 is provided with a first retainer 15 at an end portion facing the second piston 4, and the end portions of the first retainer 15 and the second piston 4 facing the first piston 3 are disposed. The first return spring 8a disposed between the second retainer 16 and the first retainer 15 and the first connective rod 17 penetrating the second retainer 16 are shown in a non-operating state. Held in position. Further, at the end portion of the first piston 3 facing the first pressure chamber 6 on the right side of the portion where the first retainer 15 is disposed, the hydraulic oil is supplied only from the first replenishment chamber 10a to the first pressure chamber 6. A seal 18 that allows the circulation of

The seal 18 closes the small hole 11 and prevents the hydraulic oil in the first pressure chamber 6 from entering the first replenishing chamber 10a when a pressing force is applied to the first piston 3. As a result, when the first piston 3 is pushed, the working oil in the first pressure chamber 6 is pressurized, and the pressure oil is braked through a port 2c formed in the cylinder body 2 (not shown). Is supplied to.

The second piston 4 forms a second replenishing chamber 10b between the outer periphery of its central portion and the inner wall of the cylinder body 2 so as to communicate with the reservoir tank via the supply port 2b.

The second piston 4 has a recess 4a that opens toward the bottom of the cylinder body 2 and the recess 4a.
And a communication passage 14 that communicates with the second supply chamber 10b. A valve 5 capable of blocking the communication passage 14 is provided in the recess 4a so as to be movable along the sliding direction of the second piston 4. In addition, the first pressure chamber 6 of the second piston 4
A seal 19 is attached to an end portion of the second piston 4 facing the second pressure chamber 7, and a seal 20 is provided to an end portion of the second piston 4 facing the second pressure chamber 7.
The second retainer 16 is disposed at the end portion of the second piston 4 facing the first pressure chamber 6, and the third retainer is disposed at the end portion of the second piston 4 facing the second pressure chamber 7 rather than the portion where the seal 20 is disposed. 21
Is provided. In addition, the second piston 4 penetrates the second return spring 8 b and the third retainer 21 and the holder 22 which are arranged between the third retainer 21 and the holder 22 fixed to the bottom of the cylinder body 2. It is held in the position shown by the two-connecting rods 23. In addition, the second connect rod 23 has a concave portion 4a at its end.
A large diameter portion 24 having a diameter slightly smaller than the diameter of the second connecting rod 23 is formed, and serves as a guide when the second connect rod 23 is moved.

The diameter of the large-diameter portion 24 is set so as not to be a resistance for hydraulic fluid to pass therethrough and required for guiding. A communication means such as a communication groove or a communication hole may be formed at several places.

The communication passage 14 has a first communication passage 14a formed perpendicularly to the axial direction of the second piston 4 communicating with the second supply chamber 10b, and a second piston 4 opened and closed by the valve 5.
The first communication passage 14a is formed in a substantially central portion of the first passage 14a along the axial direction thereof, and the second communication passage 14b communicates with the first communication passage 14a.

The seal 19 prevents hydraulic oil from entering the second pressure supply chamber 10b from the first pressure chamber 6.

The seal 20 has a structure in which the hydraulic oil in the second pressure chamber 7 is discharged from the second replenishing chamber 1 when the pressing force is applied to the second piston 4.
0b, the first piston 3 is pushed by this, and when the second piston 4 is pushed in response to this, the hydraulic oil in the second pressure chamber 7 is pressurized. Then, the pressure oil is supplied to a brake cylinder (not shown) via a port 2d formed in the cylinder body 2.

The valve 5 is connected to the second connect rod 2
3 is integrally formed on the end portion rather than the large diameter portion 24, and the seal portion 5 abuts the bottom portion of the recess 4a to shut off the second communication passage 14b, and thus the second replenishment chamber 1
0b and the reservoir tank are cut off from the recess 4b and the second pressure chamber 7. In addition, the valve 5 includes the large diameter portion 24 and the third
A valve spring 25 arranged between the retainer 21 and the retainer 21.
Therefore, the second connecting passage 14b is always urged so as to be blocked, but when not operating, the second connecting rod 23
The holder 22 moves the seal portion 5a into the concave portion 4b.
Since the second piston 4 is regulated so as not to come into contact with the bottom portion thereof, the second communication passage 14b is blocked when the second piston 4 slides by a predetermined amount or more (until it comes into contact with the valve 5).

Next, the third retainer 21 will be described with reference to FIG.

The third retainer 21 is formed so as to project in the outer peripheral direction and has a flange portion 26 with which the end portion of the second return spring 8b abuts, a tubular portion 33 with which the inner peripheral surface of the recess 4a abuts, and a tubular portion. A plurality of claw portions 27 formed so as to project at least two or more at portions of the shape portion 33 facing each other in the outer peripheral direction, a bottom portion 29 on which the valve spring 25 abuts, and a substantially central portion of the bottom portion 29. And a through hole 28 through which the second connect rod 23 penetrates. As for the claw portion 27, the tip end portion 27a has a concave portion 4a.
By engaging with the annular groove 30 formed on the inner peripheral surface of the cylinder body 2, movement of the cylinder body 2 to the bottom portion (left side in the drawing) is regulated. The bottom portion 29 has a valve spring 25 disposed between the bottom portion 29 and the large diameter portion 24 of the connect rod 23, and has a smaller diameter than the large diameter portion 24 of the connect rod 23 and a larger diameter than the through hole 28. A certain medium-diameter portion 31 is locked, so that the connecting rod 23 is prevented from coming off.

Next, a method of assembling the third retainer 21 will be described with reference to FIG.

In the third retainer 21 formed by press molding, the claw portion 27 does not project in the outer peripheral direction before the assembling, and the caulking jig 32 has a diameter slightly smaller than the tubular portion 33.
Is inserted from the left side in the drawing, the caulking jig 32 has a tapered outer peripheral end portion 32a, so that the claw portion 2 is formed.
7 is projected in the outer peripheral direction.

Next, a modified example will be described with reference to FIG.

A bent portion 34 having a diameter smaller than that of the tubular portion 33 is formed substantially in the middle of the claw portion 27 formed on the tubular portion 33 of the third retainer 21. This allows
When the caulking jig 32 is fitted and the claw portion 27 is projected in the outer peripheral direction, the tip portion 27a of the claw portion 27 is reliably locked in the annular groove 30.

[0027]

According to the present invention, a retainer for locking a return spring arranged between the bottom of a cylinder body and a retainer is provided.
Since the retainer and the piston can be fixed by engaging the claw portion protruding in the outer peripheral direction with the groove formed on the inner peripheral surface of the recess formed in the piston, the retainer can be press-molded. The number of parts can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the configuration of a master cylinder of this embodiment.

FIG. 2 is an enlarged view of a main part of a master cylinder of this embodiment.

FIG. 3 is an enlarged view of a main part when the master cylinder of the present embodiment is assembled.

FIG. 4 is an enlarged view of an essential part showing a modified example of the present embodiment.

[Explanation of symbols]

 1 ... Master cylinder 2 ... Cylinder body 4 ... Second piston (piston) 4a ... Recessed portion 5 ... Valve 7 ... Second pressure chamber (pressure chamber) 8b ... Return spring 10b ... Second supply chamber (supply chamber) 14 ... Communication passage 21 ... Third retainer (retainer) 22 ... Holder 23 ... Connecting rod 25 ... Valve spring 27 ... -Claw portion 28 ... Through hole 30 ... Annular groove (groove) 31 ... Large diameter portion 34 ... Bent portion

Claims (2)

[Claims] 1. A hollow cylinder body, a piston that is slidably fitted into the cylinder body and has a recess at the tip, and between the piston and the bottom of the cylinder body. Of the cylinder body, a replenishment chamber formed between the outer circumference of the piston and the cylinder body, a communication passage formed in the piston for communicating the pressure chamber and the replenishment chamber, A holder having a through hole fixed to the bottom, a connect rod having a large diameter portion penetrating the through hole of the holder and having one end fitted in the recess, and the connector capable of opening and closing the communication passage. A valve formed at the end of the tie rod, a valve spring for urging the valve toward the communication hole, and a return spring arranged between the holder and the piston. In the master cylinder, a groove is formed on the inner peripheral surface of the recess formed in the piston so that the through hole has a diameter smaller than that of the large diameter portion of the connectein rod, and the outer periphery is located at a position facing the groove. A master cylinder, comprising: a retainer formed with a claw portion protruding in a direction and having one end of the valve spring disposed therein. 2. The master cylinder according to claim 1, wherein a bent portion is formed on the claw portion of the retainer so as to project toward the center.