JPH0143343Y2 - - Google Patents

Description

[Detailed explanation of the invention] A. Purpose of the invention (1) Industrial application field The present invention is an assembly of a master cylinder and a negative pressure booster for operating wheel brakes, clutches, etc. of automobiles, and in particular, a master cylinder and a negative pressure booster assembly for operating vehicle wheel brakes, clutches, etc. The rear end of the cylinder body is connected to the front surface of the booster shell of the negative pressure booster, and the rod part of the piston that slides into the cylinder hole of the cylinder body is thrust into the booster shell and connected to the output rod inside the booster shell, A sealing member that closely contacts the outer circumferential surface of the rod portion is attached to a bearing that is fitted into the cylinder body and slidably supports the rod portion, and a sealing member that protrudes from the rear end surface of the cylinder body and supports the rod portion in a slidable manner. A rear sealing member that is in close contact with the outer circumferential surface of the rod portion is interposed between a positioning tube surrounding the rod portion and an end wall of a positioning recess formed in the front surface of the booster shell to receive the positioning tube. and a hollow portion of the positioning cylinder portion is communicated with a groove open to the atmosphere formed in a lower portion between opposing surfaces of the cylinder body and the booster shell.

(2) Prior Art Conventionally, this type of assembly has been disclosed in Japanese Utility Model Application Publication No. 142170/1983.

(3) Problems to be solved by the invention In the assembly disclosed in the above-mentioned publication, in order to communicate the hollow part of the positioning cylinder with the groove open to the atmosphere, a rear seal member that contacts the positioning cylinder is attached. A plurality of notches are provided radially on the front end surface, but in this case, the positioning cylinder part and the rear seal member are placed in a mere contact relationship, so when the master cylinder and negative pressure booster are separated, the rear seal member The seal remains in the locating recess and there is a risk of damaging the lip of the seal when they are reattached, particularly when inserting the rod of the piston into the rear seal.

This invention was made in view of these points,
The rear seal member is always in a connected state with the positioning cylinder, so that it does not remain in the positioning recess when the master cylinder and negative pressure booster are separated, and when they are connected, the simple structure makes it possible to close the hollow part of the positioning cylinder. It is an object of the present invention to provide such an assembly which can be brought into communication with the atmosphere.

B. Structure of the invention (1) Means for solving the problem In order to achieve the above object, the present invention provides an annular groove formed on the outer peripheral surface of the positioning cylinder part, which is formed on the outer peripheral part of the rear seal member. At the same time, an annular hook portion formed on the side is attached, and an annular passage communicating with the groove remains on one side of the annular hook portion, and a through hole communicating between the annular passage and the hollow portion is attached to the positioning tube. It is characterized by having a hole in the part.

(2) Effect If the front seal member is damaged and the master cylinder's hydraulic oil leaks from the damaged area,
The oil first leaks into the hollow part, and then naturally flows out from the through hole through the annular passage and the groove.

Additionally, if the rear seal member is damaged and the negative pressure inside the booster shell leaks from the damaged part into the hollow part, atmospheric air will flow into the hollow part through the groove, annular passage, and through hole. and eliminate the negative pressure.

Even if the positions of the through hole and the groove are shifted from each other on the circumference of the positioning cylinder, since they communicate through the annular passage, there will be no problem with the outflow of hydraulic oil and inflow of air as described above. It never comes.

When the master cylinder and the negative pressure booster are separated for maintenance, the rear seal member escapes from the positioning recess together with the positioning cylinder and does not remain in the recess.

(3) Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.A master cylinder and negative pressure booster assembly 1 has a mounting flange 2a formed at the rear end of a cylinder body 2 of a master cylinder M, which applies negative pressure. It is configured by being connected to the front surface of the booster shell 3 of the booster B with bolts 4.

The master cylinder M is configured in a tandem type by sliding a pair of front and rear pistons 6 and 7 into the cylinder hole 5 of the cylinder body 2. The inside of the cylinder hole 5 is divided into a pair of independent front and rear hydraulic chambers 8, 9 by both pistons 6, 7, and when the rear piston 7 is advanced, hydraulic pressure is generated in both hydraulic chambers 8, 9, and by these hydraulic pressures. Corresponding wheel brakes (not shown) can be activated.

The rear piston 7 has a rod portion 7a that extends rearward and penetrates the front wall of the booster shell 3.
An output rod 10 in the booster shell 3 is connected to the rod portion 7a.

The cylinder body 2 is provided with a bearing mounting hole 11 that has a larger diameter than the cylinder hole 5 and is connected to the rear end thereof, and a bearing 12 that slidably supports the rod portion 7a is mounted in the bearing mounting hole 11 with an O-ring. A circlip 14, which is fitted through the bearing 13 and comes into contact with the rear end surface of the bearing 12 to prevent it from coming off, is locked to the inner circumferential wall of a positioning cylinder 15, which will be described later.

A front seal member 16 is mounted on the inner peripheral surface of the bearing 12 and is in close contact with the outer peripheral surface of the rod portion 7a.

Further, an annular extension 12a is provided at the rear end of the bearing 12 so as to increase the effective width of the bearing surface. The extension portion 12a is connected to the circlip 14.
The circlip 14 has an attachment/detachment space a facing the inner peripheral surface thereof, and the circlip 14 engages the rod portion 7 when it is attached or detached.
a) It also has the function of preventing damage to the outer peripheral surface.

The positioning cylinder part 15 is provided so as to protrude from the rear end surface of the cylinder body 2 so as to surround the rod part 7a, and has a hollow part 15a having a diameter larger than the bearing mounting hole 11 and continuous to the rear end. A rear seal member 17 is attached to the rear end of the positioning cylinder part 15 in close contact with the outer peripheral surface of the rod part 7a to close the hollow part 15a.
This is done by elastically fitting an annular hook 19 formed on one side of the outer periphery of the rear seal member 17 into an annular groove 18 formed on the outer periphery of the rear seal member 17 .

The annular groove 18 is formed in such a size that an annular passage 20 remains on one side of the annular hook part 19 fitted therein, and the annular passage 20 and the hollow part 15a are connected to each other.
A through hole 21 is bored in the positioning cylinder portion 15 to provide communication therebetween.

On the other hand, a positioning recess 22 is formed on the front surface of the booster shell 3 in correspondence with the positioning cylinder 15, and the positioning cylinder 15 and the rear seal member 17 are fitted into the recess 22. This restricts the connection position of master cylinder M and negative pressure booster B. At this time, the rear seal member 17 is adapted to come into close contact with the inner circumferential wall and end wall of the positioning recess 22.

Further, a groove 23 is formed in the lower part of the front surface of the booster shell 3 facing the mounting flange 2a to open the annular passage 20 to the atmosphere.

Next, the operation of this embodiment will be explained. When the negative pressure booster B is operated, the output rod 10 is boosted and moves forward, and the rear piston 7 is moved forward via the rod portion 7a.
advance. At this time, the front seal member 16 slides into contact with the outer peripheral surface of the rod portion 7a to prevent leakage of hydraulic oil from the cylinder hole 5, and the rear seal member 16
7 also slides into contact with the outer circumferential surface of the rod portion 7a to prevent negative pressure from leaking from the booster shell 3.

In the unlikely event that the front seal member 16 is damaged and the hydraulic oil in the cylinder hole 5 leaks from the damaged part, the oil will first leak into the hollow part 1 of the positioning cylinder part 15.
5a, and then from the through hole 21 to the annular passage 2.
0 and the concave groove 23 to the outside naturally,
Oil is prevented from accumulating in the hollow portion 15a and entering the booster shell 3.

In addition, if the rear seal member 17 is damaged and the negative pressure inside the booster shell 3 leaks from the damaged part to the hollow part 15a, the air in the atmosphere will immediately leak into the groove 23, the annular passage 20, and the through hole. 21 into the hollow portion 15a and eliminates the negative pressure, leakage negative pressure is prevented from acting on the back surface of the front seal member 16 and causing oil leakage from the front seal member 16.

In this case, the through hole 2 is placed on the circumference of the positioning cylinder 15.
Even if the positions of 1 and the groove 23 are shifted from each other, since they communicate through the annular passage 20, there will be no problem with the outflow of hydraulic oil and the inflow of air.

When the positioning cylinder part 15 of the master cylinder M is pulled out from the positioning recess 22 of the negative pressure booster B in order to separate the master cylinder M and the negative pressure booster B for maintenance, the rear seal member 17 is connected to the positioning cylinder part 15. Therefore, the cylinder part 15 escapes from the positioning recess 22 together with the cylinder part 15. In this way, the rear seal member 17 and the rod portion 7 are connected not only when the master cylinder M and the negative pressure booster B are separated, but also when they are connected.
Since unnecessary friction with the rod portion 7a is avoided, there is no risk that the lip of the rear seal member 17 will be damaged by the rod portion 7a.

C. Effects of the invention As described above, according to the invention, the annular hook formed on one side of the outer periphery of the rear seal member is attached to the annular groove formed on the outer periphery of the positioning cylinder, and An annular passage communicating with the groove remains on one side of the hook, and a through hole communicating between the annular passage and the hollow part is bored in the positioning cylinder, so the rear seal member is always connected to the positioning cylinder. is in a state,
Therefore, when the master cylinder and the negative pressure booster are separated, they do not remain in the positioning recess, and when they are reconnected, it is possible to prevent them from being damaged by the rod portion of the piston.

Further, since the through hole and the groove communicate with each other via the annular passage, it is possible to ensure that the hydraulic oil flows out of the hollow part of the positioning cylinder and air flows into the hollow part.

Moreover, since the annular passage is defined by the annular groove for attaching the rear seal member to the positioning cylinder, there is no need to specially cut the annular passage in the positioning cylinder, and the structure is simple.

[Brief explanation of drawings]

FIG. 1 is a vertical side view showing an embodiment of the present invention;
Figure 2 is an enlarged view of the main part. B... Negative pressure booster, M... Master cylinder,
DESCRIPTION OF SYMBOLS 1... Assembly, 2... Cylinder body, 2a... Mounting flange, 3... Booster shell, 5... Cylinder hole, 7... Piston, 7a... Rod part, 1
0...Output rod, 11...Bearing mounting hole, 12...Bearing, 15...Positioning cylinder part, 15a...Hollow part,
16... Front seal member, 17... Rear seal member, 18... Annular groove, 19... Annular hook, 20...
...Annular passage, 21...Through hole, 22...Positioning recess, 23...Concave groove.

Claims (1)

[Scope of utility model registration request] The rear end of the cylinder body of the master cylinder is attached to the front face of the booster shell of the negative pressure booster, and the rod part of the piston that slides into the cylinder hole of the cylinder body is thrust into the booster shell and connected to the output rod inside the booster shell. A sealing member that is in close contact with the outer circumferential surface of the rod portion is attached to a bearing that is connected to the cylinder body and that is fitted into the cylinder body and slidably supports the rod portion, and that is provided so as to protrude from the rear end surface of the cylinder body. a positioning cylinder part surrounding the rod part;
A rear seal member that is in close contact with the outer peripheral surface of the rod portion is interposed between the end wall of a positioning recess formed in the front surface of the booster shell in order to fit the positioning cylinder portion into the cylinder body and the booster shell. In an assembly of a master cylinder and a negative pressure booster, the hollow part of the positioning cylinder part is communicated with a groove open to the atmosphere formed in the lower part between the opposing surfaces of An annular hook formed on one side of the outer periphery of the rear seal member is attached to the annular groove, and an annular passage communicating with the groove is left on one side of the annular hook, and the annular passage is connected to the annular groove. An assembly of a master cylinder and a negative pressure booster, characterized in that a through hole is bored in the positioning cylinder part to communicate between the hollow part and the hollow part.