JPH0445971Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a master cylinder used in vehicles and the like.

[Conventional technology]

As this kind of master cylinder, it was developed in 1980.
There is one shown in Publication No. 84478. This master cylinder has a passage inside the piston, one end of which is open at its end face, and the other end of which is opened at the side circumference to communicate the pressure chamber in the cylinder body with the hydraulic fluid reservoir. The valve body has a valve body that connects and disconnects the pressure chamber from the passageway, and the valve body extends into the passageway and uses the passageway as a guide part, and the valve body is in an open position when the piston is inactive. A shaft member extends and engages an end face with a stopper that is positioned at the stopper.

[The problem that the idea aims to solve]

In a master cylinder with such a structure,
When reducing the diameter of the cylinder body, it becomes difficult to guide the shaft member without obstructing the desired flow of hydraulic fluid into the passage, ensuring smooth relative movement of the shaft member to the passage. This may lead to variations in the seating position of the valve body,
This may cause scratches on the sheet surface.

Further, in this master cylinder, since the stopper is passed through the cylinder body from the side in the radial direction, there is a problem in that liquid leakage is likely to occur.

The present invention was developed to solve the above problem, and even when the cylinder body and piston are manufactured with a small diameter, the pressure chamber and the hydraulic fluid reservoir side can be communicated.
It is an object of the present invention to provide a master cylinder that can secure and maintain good sealing performance of a valve body that shuts off.

[Means for Solving the Problems] In order to achieve the above object, the present invention has a tapered shape that fits into the passage and whose outer diameter decreases as it moves away from the valve body, at the end of the valve body on the valve seat side. In addition to forming a protrusion, a guide portion is provided that extends the shaft member on the opposite side of the protrusion to position the shaft member in the radial direction and guide the shaft member in the axial direction.

[Effect]

In the present invention, in order to keep the valve body in a position away from the valve seat, the shaft member formed integrally with the valve body does not extend into the piston, but extends toward the pressure chamber, so that the piston diameter Even if the liquid passage is small, it is possible to secure a sufficient liquid passage inside the piston, and in addition, a guide part is provided to guide the shaft member of the valve body, and a short protrusion protrudes into the through hole that becomes the liquid passage inside the piston. , the valve body is guided in its radial movement with its radial movement restricted at two separate locations on both sides, and there is no risk of the valve body becoming distorted.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a cylinder body of a tandem master cylinder, which has a cylinder hole 2 that is open at one end (the right end in the figure) inside. Two boss portions 4 and 5 are formed to protrude at a predetermined interval in the longitudinal direction and are fitted and connected to each other, and a discharge portion (not shown) opening into a slave pressure chamber (to be described later) is provided on the side of the front end portion. A discharge part (not shown) is formed so as to protrude from the discharge part, and is spaced apart from the discharge part by a predetermined distance and opens into a main pressure chamber, which will be described later.

The cylinder hole 2 is a stepped hole in which a fitting recess 7 is formed at its closed end 6 and whose opening 8 has a large diameter. 10, a sealing member 11, and a backer 12
A mouth device consisting of the above is fitted, and the mouth device is prevented from coming off by a case 14 fitted externally to the open end 13 of the cylinder body 1. The above pressing member 1
0 has an annular protrusion 10A protruding into the cylinder hole 2 and an annular protrusion 10B protruding into the sealing member (lip seal). Further, one end of a liquid replenishment path 15 communicating with the hole bottom of the boss portion 5 is opened in the step surface 9 of the opening 8, and this liquid replenishment path 15 is inserted into the cylinder through the groove 10C formed in the holding member 10. It communicates with the inside of hole 2. One end of a cylindrical member 16 having a cross-sectional shape shown in FIG. 2 and serving as a centering member is fitted into the fitting recess 7 of the closed end 6 of the cylinder hole 2. A shaped spring receiver 17 is fitted onto the outside. The hole 18 of this cylindrical member 16 has three axial grooves 18A, 18B, 18C.
a hole having a retaining protrusion 16A at a predetermined position in the axial direction from the other end of the outer circumferential surface of the cylindrical member 16.
is formed. A small hole 17A is formed on the inner surface of the spring receiver 17 to engage with the protrusion 16A.

A slave piston 20 is slidably inserted into the cylinder hole 2 on the cylindrical member 16 side via a return spring 21, and defines a slave pressure chamber X between it and the closed end 6. A head portion 25 of a main piston 23 having a shaft portion 24 is slidably inserted into the portion 8 side with a return spring 22 interposed between the main piston 23 and the slave piston 20 . The head 25 of the main piston 23 is connected to the slave piston 20
A main pressure chamber Y is defined between the two. The slave piston 20 has a through hole 26A between it and the inner peripheral surface of the cylinder hole 2.
A liquid replenishment path 28 is defined by sliding portions 26 and 27 having the same diameter, and a replenishment hole 29 that communicates the liquid replenishment path 28 with the bottom of the boss portion 4 is formed in the cylinder body 1. The return spring 21 is fitted onto the front end of the slave piston 20, and the claw 30A is engaged with an engagement groove 20A formed on the inner periphery of the opening of a recess, which will be described later, in the front end to prevent the spring receiver 30 from coming off. Uke 1
It is stretched over 7. The return spring 22 is fitted onto the head 25 of the piston 23 and stretched over a spring receiver 31 that is locked to prevent it from coming off, and a spring receiver 40 that is externally fitted on the rear part of the slave piston 20. The shaft portion 24 of the main piston 23, which is defined by the head portion 25 and the sliding portion 25B, slidably extends through the mouth device to the outside. A through hole 25C is formed in this sliding portion 25B. 33 is a lip seal fitted onto the head 25.

As shown in an enlarged view in FIG. 3, the head 25 of the main piston 23 has a deep hole-shaped recess 34 that opens at its end surface, and one end that opens at the bottom of the recess 34 and extends in the axial direction of the piston. A small-diameter through hole 35 is formed with one end bent in the piston radial direction and opened at the piston side peripheral portion near the sliding portion 25B. Recess 34
has a valve body 37 fitted with a valve member 36 at its end.
The valve body 37 has a tapered protrusion 38 that protrudes from the end toward the hole 35 and is loosely fitted into the hole 35, and a follower. The shaft member 39 has a shaft member 39 extending toward the piston 20, and the shaft end head 39A is connected to the hole 31B of the spring receiver 31 and the hole 27A of the spring receiver 27.
The guide hole 41 extends in the axial direction and opens at the rear end of the slave piston 20, and is slidably inserted into the guide hole 41 extending in the axial direction. This guide hole 41 communicates with a radial through hole 41A that opens on the rear end side peripheral surface of the slave piston 41. The valve member 36 constitutes a first valve whose valve seat is around the opening of the through hole 35 of the recess 34, and the first valve is open when the main piston 23 is not in operation. The slave piston 20 also has a recess 4 that opens on the end face of the front end.
2. A small diameter through hole 43 is formed, one end of which opens at the bottom of the recess 42, extends in the axial direction of the piston, and one end bends in the radial direction of the piston, opening at the piton side periphery that defines the liquid supply path 28. ing. A valve body 45 having a valve member 44 fitted to the end thereof is stored in the recess 42 and is biased toward the through hole 43 side by a valve spring 46. A tapered protrusion 47 that protrudes toward the through hole 43 and is loosely fitted into the through hole 43, and a shaft member 48 that extends toward the slave piston 20 side.
The shaft member 48 has a hole 30B of the spring receiver 30,
It passes through the hole 17B of the spring receiver 17 and the head part 48
A is slidably fitted into the guide hole 18 of the cylindrical member 16. The valve member 44 is connected to the through hole 4 of the recess 42.
3 constitutes a second valve whose opening periphery serves as a valve seat;
The valve is open when the slave piston 20 is not actuated.
50 is a sealing member fitted onto the sliding portion 27.

In addition, the hole 31A of the spring receiver 31, the spring receiver 40
As shown in FIG. 4, the hole 40A is a potbelly hole consisting of a large diameter hole A through which the head 39A of the shaft member 39 passes during assembly, and a small diameter hole B through which the shaft member 39 is guided after assembly. . The hole 17B of the spring receiver 17 and the hole 30A of the spring receiver 30 also have a large diameter hole A for passing the head 48A of the shaft member 48 of the valve body 45 during assembly, and a small diameter hole A for guiding the head 48A after assembly. It is a potbellied hole consisting of hole B. Note that after the spring receiver 17 and the shaft member 48 are engaged through the pothole, the cylindrical member 16 is fitted into the spring receiver 17 and coupled.

Further, the tapered protrusion 38 of the valve body 37 has a base having a diameter slightly smaller than the diameter of the through hole 35,
The tapered protrusion 47 of the valve body 45 also has its base connected to the through hole 4.
It has a diameter slightly smaller than the hole diameter of No. 3.

Since the operation of this master cylinder is well known,
A brief explanation will be given below.

FIG. 1 shows a state in which the brake pedal is not operated, and the head 39A of the shaft member 39 of the valve body 37 is shown in FIG.
is engaged with the spring receiver 40 to restrict rightward movement,
The valve member 36 is unseated and the first valve is open. Further, the head 48A of the shaft member 48 of the valve body 45 engages with the spring receiver 17 and is restricted from moving to the right, and the valve member 44 is unseated and the second valve is opened.
That is, the spring receivers 17 and 40 are connected to the valve bodies 37 and 40, respectively.
It plays the role of a stopper for 45. The slave pressure chamber X has a supply hole 29, a liquid supply path 28, and a through hole 4
3. The working fluid is filled through the recess 42, and the main pressure chamber Y has a fluid supply path 15, a fluid passage 10C, a through hole 35,
The recess 34 is filled with hydraulic fluid.

In this state, when the push rod (not shown) connected to the main piston 23 is pushed to the left in the drawing by depressing the brake pedal (not shown), the slave piston 20 and the main piston 23 move in the same direction, and the valve member 44 opens. Through hole 4 at the bottom of recess 42
When the slave piston 20 is seated around the third opening and further moves in the same direction, hydraulic pressure is generated in the slave pressure chamber X, and the hydraulic pressure is supplied to the brake device through a discharge portion (not shown). On the other hand, the valve member 36 is seated around the opening of the through hole 35 at the bottom of the recess 34, and the further main piston 2
3 to the left, hydraulic pressure is generated in the main pressure chamber Y, and this hydraulic pressure is supplied to the brake device through a discharge part (not shown).

In this embodiment, the shaft member 39 of the valve body 37 and the shaft member 48 of the valve body 45 extend toward the main pressure chamber Y and the slave pressure chamber X, respectively, and into the through holes 35 and 43. does not extend, and only short tapered protrusions 38 and 47 extend into the through holes 35 and 43, so even if the diameters of the through holes 35 and 43 are made small, sufficient A liquid passage can be secured.

Moreover, in this embodiment, the tapered protrusion 38 protrudes from the valve body 37 into the through hole 38, and when the valve member 36 is seated, the base of the tapered protrusion 38 is located at the open end of the through hole 38. Since the diameter is formed to be slightly smaller than the diameter of the through hole 38, the seating position of the valve member 36 is always regulated to a constant position. Also,
When the main piston 23 moves to the left after the valve member 36 is seated around the opening of the through hole 35, the valve body 3
7 moves in the same direction as the main piston 23,
The head 39A of the shaft member 39 of the valve body 37 is connected to the guide hole 4.
1 and is guided by the guide hole 41, there is no fear that the posture of the valve body 37 will be distorted.
There is also no risk of damage to the seat surface of the valve member 36. In this embodiment, the two spring receivers 40 and 31 through which the shaft member 39 passes have a hole B that guides the movement of the shaft member 39, which further enhances the above effect. Similarly, the tapered protrusion 47 protruding from the valve body 45 on the side of the slave piston 20 is also connected to the valve member 44.
When the valve member 44 is seated, its base is located at the open end of the through hole 43, and the diameter of the base is formed to be slightly smaller than the diameter of the through hole 43, so the seating position of the valve member 44 is always constant. Regulated by location. Further, when the slave piston 20 moves to the left after the valve member 44 is seated around the opening of the through hole 43, the valve body 45 moves in the same direction together with the slave piston 20.
Since the head 48A of the shaft member 48 of No. 5 slides within the guide hole 18 and is guided by the guide hole 18,
The valve member 4 can be moved without fear that the posture of the valve body 45 will be distorted.
There is no risk of scratches on the seat surface of 4. In this case, the spring receiver 30 through which the valve body 45 and the shaft member 48 pass
The hole 30B of the shaft member 4 and the hole 17B of the spring receiver 17 are
Since it has the hole A that guides 8, the above effect is promoted.

In FIG. 5, a cylindrical member 161, one end of which is fitted into the fitting recess 7 of the closed end 6 of the cylinder bore 2, is made of metal and closed at one end. As shown in FIG. 6, a round hole 162 consisting of a large diameter hole A and a small diameter hole B is formed in the closed wall of this cylindrical member 161. The small diameter member B of the round hole 17A of the spring receiver 17 is concentrically overlapped with the round hole 162, and apparently cooperates with the large diameter hole A to form a single hole.
The circular hole 162 is formed in the head 48 of the shaft member 48 of the valve body 45.
Although the diameter of the spring retainer 17 is smaller than that of the spring retainer 17, the spring retainer 17 has a diameter sufficient to guide the other portion of the shaft member 48. Therefore, even after the valve body 45 is combined with the slave piston 20 and the spring retainer 30 is attached to the slave piston 20, the spring retainer 17 can be guided by the large diameter hole A of the spring retainer 17 and the large diameter hole A of the cylindrical member 16.
can be inserted into the cylindrical member 16 so as not to come off, and after assembly, the hole 162 serves as a guide hole for the shaft member 48.

FIG. 7 shows another embodiment of the present invention.
In place of the cylindrical member 16 in FIG. 1 and the cylindrical member 162 in FIG.
The guide member 163 has a cylindrical portion 163A and a flange portion 163B, and the opening portion 42 is formed to have a larger diameter than other portions.
It is fixedly inserted into A with a retaining ring 52 to prevent it from coming off.

[Effect of idea]

As explained above, in the present invention, in order to maintain the valve body in a position separated from the valve seat, the shaft member formed integrally with the valve body does not extend into the piston, but extends toward the pressure chamber side. Therefore, it is possible to secure a sufficient liquid passage inside the piston, and in addition, a guide part is provided to guide the shaft member of the valve body, and a short tapered protrusion that protrudes into the through hole that becomes the liquid passage inside the piston is provided. By forming the valve body, the radial movement of the valve body is restricted and guided at two separate locations on both sides, and the seating position of the valve body is prevented from shifting and the valve body is prevented from becoming distorted. Because it is possible to
Even if the piston diameter is made small, there is no risk of damaging the sealing performance of the valve body.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the present invention, Fig. 2 is a sectional view of the main part in the - arrow direction of Fig. 1, Fig. 3 is an enlarged sectional view of the main part in Fig. 1, and Fig. 4 is a sectional view of the main part in Fig. 1. A diagram showing the shape of the hole that each spring receiver has in FIG. 1,
FIG. 5 is a partial sectional view showing another embodiment of the present invention;
FIG. 6 is an enlarged view of section A in FIG. 5, and FIG. 7 is a diagram showing still another embodiment of the present invention. 1...Cylinder body, 2...Cylinder hole, 1
6,161,163... Cylindrical member having a guide portion,
17, 40... Spring receiver that also serves as a stopper, 20
... Slave piston, 21, 22 ... Return spring, 23
...Main piston, 30, 31...Spring receiver, 3
5,43...Through hole, 37,45...Valve body, 38,
47... Taper part, 39, 48... Shaft member, 41
...Guide hole, X...Subpressure chamber, Y...Main pressure chamber.

Claims (1)

[Scope of utility model registration request] a main body having a cylinder hole formed therein; a piston slidably inserted into the cylinder hole; a pressure chamber defined within the cylinder hole by the piston; and a pressure chamber formed in the piston and opening at an end of the piston. a passage communicating the pressure chamber with a hydraulic fluid reservoir; a valve body disposed opposite the opening of the passage; and a return spring biasing the valve body against a valve seat formed around the opening of the passage; A shaft member integrally provided with the valve body with an outer diameter smaller than this, and a shaft member that engages with the shaft member when not in operation to push the valve body against the biasing force of the valve spring and push the valve seat toward the valve seat. A master cylinder having a stopper for unseating the valve body from the valve body, wherein a tapered protrusion is formed on the valve seat side end of the valve body to fit into the passage and whose outer diameter becomes smaller as the distance from the valve body increases. . A master cylinder provided with a guide portion that extends the shaft member on a side opposite to the protrusion, positions the shaft member in a radial direction, and guides the shaft member to move in the axial direction.