JPH0310542B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is a plunger type master cylinder used in a brake device of a vehicle, etc., and particularly suitable for use in an air-over-hydraulic booster where high pressure is generated. Regarding plunger type master cylinder.

(Prior Art) The basic structure of a plunger type master cylinder is as disclosed in, for example, Japanese Utility Model Application No. 58-8667.
The cylinder body has a pneumatic cylinder hole and a hydraulic cylinder hole, and is a pneumatic chamber behind a piston that is movably inserted into the pneumatic cylinder hole, and is moved by the air pressure introduced into the pneumatic chamber. The piston displaces the plunger inserted into the hydraulic cylinder hole, thereby increasing the hydraulic pressure in the pressure chamber defined by the plunger.

In this case, the conventional structure that ensures a seal between the hydraulic cylinder hole wall and the outer circumference of the plunger and a passage for compensating the hydraulic fluid from the starting fluid reservoir to the pressure chamber is as follows:
A sealing member is attached to the groove formed in the hydraulic cylinder hole so that the plunger can slide through it, and the inner periphery of a ring-shaped seal/backup member is placed in contact with the low pressure side of the sealing member. The large inner diameter portion extends over a predetermined range, the gap between the wall of the large inner diameter portion and the outer periphery of the plunger is used as a first passage, and the through hole connected to the hydraulic fluid reservoir provided in the seal backup member is used as the first passage. and a second passage is provided in the plunger, one end of which opens on the outer periphery facing the first passage, and the other end of which communicates with the pressure chamber, and the plunger is moved forward by the driving of the piston; When the opening of the second passage exceeds the sealing member, communication between the first passage and the second passage is cut off, thereby sealing the pressure chamber.

(Problems existing in the prior art) In the above conventional structure, when high pressure is generated in the pressure chamber, an acting force is generated in the pressure chamber that presses the sealing member toward the low pressure side, but as described above, when the pressure chamber comes into contact with the sealing member, Since the first passage is formed in the gap between the inner diameter of the seal back-up member which is arranged and backed up over a predetermined range over a predetermined range as the large inner diameter part, and the outer circumference of the plunger, the seal member is moved by the above-mentioned acting force. Since the base part deforms and enters the first passage, the base part is likely to be eaten away by sliding of the plunger, causing wear and tear on the sealing member, which is a problem in that it is difficult to guarantee the durability of the sealing member. Ta.

(Object of the Invention) The present invention is directed to a conventional structure for sealing the hydraulic cylinder hole wall and the outer periphery of the plunger in a plunger-type master cylinder and ensuring a passage for compensating the flow of hydraulic fluid into the pressure chamber from the hydraulic fluid reservoir to the pressure chamber. This invention has been made in order to solve the above-mentioned existing problems, and an object thereof is to provide a plunger type master cylinder that can prevent the base of the sealing member from being eaten away and ensure durability.

(Structure of the Invention) In order to achieve the above object, the present invention forms a large inner diameter portion communicating with the hole on the groove side inner periphery of the backup member, and a first
A ring member is disposed, the inner circumference of which is slidable on the plunger and whose end face on the side of the sealing member is aligned with the end face of the back-up member, forming a cavity used as a passage for the cavity and the sealing member. A thin annular deformable member having a wave shape in the circumferential direction is disposed between the two and the annular deformable member is configured to be elastically deformable by the force exerted by the pressure of the pressure chamber.

(Example) The present invention will be described in detail below according to an example shown in FIGS. 1 to 2b.

In FIG. 1, 1 is a plunger type master cylinder, 2 is a pneumatic cylinder hole, 3 is a hydraulic cylinder hole whose end face in the two directions of the pneumatic cylinder hole is open, and 4 is a hydraulic cylinder hole from a hydraulic fluid reservoir (not shown). 3
It is a conduit that compensates the hydraulic fluid.

A piston 21 that divides the hole into two is inserted into the pneumatic cylinder hole 2 so as to be able to slide on the hole wall, and high-pressure air is introduced from an inlet 22 that opens into a pneumatic chamber on the left side in the figure. When introduced, the piston 21 moves to the right against the spring force of the spring 23 inserted between the piston 21 and the opening periphery of the hydraulic cylinder hole 3. A plunger 5 whose tip end is fitted into the hydraulic cylinder hole 3 is pivotally attached to the right end surface of the piston 21, and the plunger 5 is connected to the piston 2.
1 can be displaced rightward within the hydraulic cylinder hole 3. In addition, 24 is the piston 21
This is a mechanism that detects the stroke of the

An airtight member 31 for airtightly holding the pneumatic cylinder hole 2 from the sliding plunger 5 is fitted into the open end face opening of the hydraulic cylinder hole 3, and an annular seal is provided on the right side of the airtight member 31. A backup member 32 is fitted into the hole, and a groove 34 of a predetermined width is formed between the back-up member 32 and the step 33 of the hole wall. The groove 34
There is a pressure chamber 3 on the right closed end side of the hydraulic cylinder hole 3.
Double lip type sealing member 6 for dividing 0
is installed. Lip portion 6 of the sealing member 6
1a and 61b have a tulip shape with their tips opening outward, and maintain a gap between the inner diameter of the ring of the base portion 62 and the outer periphery of the opposing plunger 5.
The tip of the inner lip 61a is shaped to abut against the outer periphery of the plunger 5 to define the pressure chamber 30. Further, the seal/backup member 32 has a large inner diameter 35 over a predetermined range of inner diameter in the direction of the sealing member 6, and the conduit 4 for supplying the hydraulic fluid from the hydraulic fluid reservoir to the hydraulic cylinder hole 3 is connected to the seal. - A through hole 321 formed in the backup member 32 communicates with a first passage A consisting of a gap between the inner wall of the large inner diameter portion 35 and the outer periphery of the plunger 5. The plunger 5 is provided with a through hole that is open at one end on the outer periphery of the plunger 5, communicates with the other end on the end face toward the pressure chamber 30, and is connected to the concave end face in the embodiment. It forms a passage B. Furthermore, a passage C communicating with a brake mechanism of a vehicle or the like is opened at the bottom surface of the hydraulic cylinder hole 3 in which the pressure chamber 30 is formed.

In the configuration of the present invention, as shown in FIG. 2a, which is an enlarged view of one side of the groove 34, the sealing member 6 has a flange with a flange 71 in contact with the step between the lip portions 61a and 61b. A first passage A is disposed in the groove 34 so as to sandwich the tip of the ring 7, and is formed in the gap between the inner wall of the large inner diameter portion 35 of the seal backup member 32 and the outer periphery of the plunger 5. a width equal to the length of the first passage A;
A ring member 8 having an inner diameter on which the outer circumference of the plunger 5 can slide and an outer diameter smaller than the inner diameter of the large inner diameter portion 35 of the seal/backup member 32 by a predetermined amount is disposed on the outer circumference of the plunger 5, and furthermore, the ring member 8 has an inner diameter on which the outer circumference of the plunger 5 can slide. The specifications are set so that a predetermined gap 36 exists between the end surface of the base portion 62 of No. 6 and the end surface of the seal backup member 32 facing thereto, and the gap 36 is shown as 9 in FIG. 2b. A thin annular deformable member having a wavy shape in the circumferential direction is provided. When high pressure is generated in the pressure chamber 30 and the sealing member 6 is pushed toward the seal backup member 32, the annular deformable member 9 is pressed against the seal backup member by the end surface of the base portion 62 of the sealing member 6. It is made of a thin elastic member that can be compressed against the end face of 32 and deformed flat by reducing the wave height.

In the configuration of the present invention, the first passage A is secured between the outer periphery of the ring member 8 and the inner wall of the large inner diameter portion 33 of the seal backup member 32, and the first passage A is formed in the annular shape. It can communicate with the second passage B through a predetermined gap formed between the wave-shaped gap of the member 9 and the outer periphery of the plunger 5 on the inner periphery of the ring of the base portion 62 of the sealing member 6.

Therefore, when the plunger 5 is displaced in the direction of the pneumatic cylinder hole 2, a compensation path for the hydraulic fluid to the pressure chamber 30 is secured, and the plunger 5 is displaced in the direction of the pressure chamber 30, and the second When the opening of the passage B crosses the sealing member 6 and enters the pressure chamber 30, communication between the first passage A and the second passage B is cut off, and the pressure chamber 30 is sealed.

(Operation of the Invention) In the present invention having the above-described configuration, the plunger 5 is displaced toward the bottom surface of the hydraulic cylinder hole 3, and the pressure chamber 3 is
When high pressure is generated in the pressure chamber 30, the sealing member 6 receives the acting force of the pressure inside the pressure chamber 30.
While pushing the annular deformable member 9 disposed in the gap between the seal back-up member 32 and the seal back-up member 32, the annular deformable member 9 pressed by the seal member 6 deforms the seal member 6. Instead, the ring member 8 reduces the wave height and deforms into a flat surface to absorb the acting force, and the ring member 8 with the plunger 5 disposed on the outer periphery secures the first passage A and seals with the outer periphery of the plunger 5. - Since there is almost no gap between the sealing member 6 and the backup member 32 and the annular deformable member 9 deforming in a plane, the sealing member 6 is not allowed to enter the first passage A.

In this way, since the space between the seal backup member 32 and the ring member 8 is used as the first passage, the space between the seal backup member 32 and the inner peripheral surface of the cylinder hole, and between the ring member 8 and the plunger 5 The gaps between the two can be made as small as possible, and the sealing member 6 can be reliably prevented from being eaten by these gaps.

On the other hand, the air space between the seal backup member 32 and the ring member 8 as the first passage prevents the sealing member 6 from being eaten away by the deformation of the annular deformable member 9, and also allows liquid replenishment and relaxation. During this process, a sufficiently large passage can be formed by restoring deformation of the seal backup member 32, so that liquid movement is not obstructed.

Note that the passage secured by the annular deformable member 9 also becomes smaller as it deforms in response to the increase in pressure, so that it will not be eaten away.

(Effects of the Invention) By carrying out the present invention, (1) there is no erosion of the sealing member, and therefore, wear and tear of the sealing member due to erosion is prevented, increasing the reliability of the plunger type master cylinder; This will extend the service life, especially for air-over-hydraulic systems where high pressure is generated in the pressure chamber.
(2) Not only the plunger type master cylinder of the above embodiment, but also a type in which the plunger is pressed by a bushing rod connected to the brake pedal instead of a pneumatic cylinder, or a vacuum booster, etc. It can also be applied to a type of pressing method, and the effects brought about by this method are enormous.

[Brief explanation of the drawing]

FIG. 1 is an overall cross-sectional front view of a plunger type master cylinder according to an embodiment of the present invention, FIG. 2 a is an enlarged cross-sectional view of the main part in FIG. 1, and FIG. FIG. 1...Plunger type master cylinder body, 3...
...Cylinder hole, 30...Pressure chamber, 34...Groove, 5
... Plunger, 6 ... Sealing member, 8 ... Ring member, 9 ... Annular deformation member, A ... First passage,
B...Second passage.

Claims (1)

[Claims] 1. A cylinder body having a cylinder hole with one end closed, in which a groove for mounting a sealing member between the stepped portion and the backup member is formed on the open end side, and a cylinder body that penetrates the backup member and the sealing member from the open end side. a plunger that fits into the hole to define a pressure chamber; and a first plunger that is provided on the low pressure side of the sealing member and includes a radial hole provided in the backup member and communicates the hydraulic fluid reservoir with the low pressure side of the groove. a passageway, and a second passageway formed in the plunger, one end opening to the outer periphery of the plunger and the other end opening to the pressure chamber, allowing communication between the first passageway and the pressure chamber; In a plunger type master cylinder in which the opening of the second passage exceeds the sealing member due to forward movement, the first passage and the second passage are cut off and the pressure chamber is sealed. A large inner diameter portion is formed that communicates with the hole, and the inner circumference is slidable on the plunger while forming a space between the large inner diameter portion and the inner circumferential surface of the large inner diameter portion to be used as a first passage. A ring member whose side end face coincides with the end face of the back-up member is disposed, and a thin annular deformable member having a wavy shape in the circumferential direction is disposed between the cavity and the sealing member to prevent the annular deformation. A plunger type master cylinder characterized in that the member is configured to be elastically deformable by the force exerted by the pressure of a pressure chamber.