JPS61244656A - Plunger type master cylinder - Google Patents

Abstract

PURPOSE:To secure a sufficient gap for a passage while prevent a sealing member from being caught in on a low pressure side by providing a spacer having a part which is subjected to elastic deformation and a part which is not subjected to elastic deformation. CONSTITUTION:A ring member 40 made of a synthetic resin, has sliding member 41 and a rubber deformable member 42 provided in an integrated form with the outer periphery of the sliding member 41. The sliding member 41 forms a gap in such a degree that it is impossible for a sealing member 9 to enter the outer periphery of a plunger 41 depending on a pressure generated in a hydraulic chamber 12. The ring member 40 is placed at the end surface part of a spacer 7. One of the projections 43 of the deformable member 42 is in contact with the spacer 7 while the other is in contact with the base part 9c of the sealing member 9 forming a continued small port 45. This small port 45 is connected to a small port 11b via a space part 18 on the left on an inner lip 9a while also connected to a passage 19 to connect a hydraulic chamber 12 to a hydraulic fluid reservoir.

Description

Detailed Description of the Invention (Field of Industrial Application) This invention relates to a plunger-type master cylinder used in vehicles, etc., and in particular, to a plunger-type master cylinder used in large automobiles, construction vehicles, etc., which generates relatively low pressure during use. It relates to something that is suitable for application to things that are expensive.

(Prior Art) As one of this type of plunger type master cylinder, there is one that is operated by compressed air discharged based on the driver's operation, as shown in Japanese Utility Model Application Publication No. 60-30868, for example. Are known.

This conventional example will first be clarified with reference to FIGS. 5 and 6.

In Fig. 5, the one indicated by the symbol 1- as a whole is an air-over-hydraulic type booster that is supplied with compressed air as input pressure, converts it into hydraulic pressure, and outputs it. The pneumatic part 2 is on the right side, and the hydraulic part 3 is on the right side.
Each has

The hydraulic part 3 on the right side has a main body 5 in which a cylinder hole 4 is formed.
There is. The cylinder hole 4 has a stepped shape, and a stepped spacer 7 is fitted into a stepped increased diameter portion 6 on the left side thereof. The spacer 7 is firmly supported between the stepped portion 6a and a retainer 8 provided on the open end side, and is thereby fixed. This spacer 7 has a groove 10 formed between its right end and a step 6b on the right side of the increased diameter section 6, and the groove 10 has a lip seal having inner and outer lips 9a and 9b facing right. 9 is installed. The plunger 1-1 is slidably passed through the tongue seal 9 and the spacer 7, and is fitted into the cylinder hole 4, defining a hydraulic chamber 12 in the right side of the cylinder hole 4.

The hydraulic chamber 12 has a residual pressure valve 13 on the right end side of the main body 5.
It communicates with the discharge hole 15 via a communication chamber 14 that accommodates the. This discharge hole 15 can supply pressurized fluid to a wheel brake device (not shown) through a pipe (not shown) connected thereto. Further, a hole 16 communicates with the hydraulic pressure chamber 12, and the hole 16 is closed by a bleeder screw 17.

The residual pressure valve 13 is a well-known type that maintains pressure to the extent that the brake is not applied to the wheel brake device side, and a detailed explanation thereof will be omitted. On the other hand, the hydraulic chamber 12 communicates with a hydraulic fluid reservoir (not shown) through a joint 2o in the center of the main body 5. The connection between the hydraulic chamber 12 and the joint 20 is as follows.

The hydraulic chamber 12 is first located in a recess 11a at the end of the plunger 11.
and a large number of small holes 1 extending radially from this recess 11a.
1b to the left-hand cavity 18 of the inner lip 9a of the lip seal 9 which rests resiliently on the plunger 11, and furthermore, referring to FIG. 6, an annular passage 19 between the plunger 11 and the increased diameter of the spacer 7; The annular passage 19 is connected to a large number of holes 7a provided radially in the spacer 7, the outer peripheral groove 7b connected to the hole 7a is provided in the spacer 7, and then the hole 5a provided in the main body 5 is connected to the joint 2o. It comes down to parts. Note that these paths are connected to the O-ring 21 attached to the joint 20.
Communication with the outside air is blocked by an O-ring 21N mounted slightly to the left of the outer circumferential groove 7b of the spacer 7, a tongue seal 228 mounted to the left of the inner hole of the spacer 7, and the like. Further, between the spacer 7 and the plunger 11, a split sleeve 23 made of synthetic resin for slidingly guiding the plunger 11, and a lip seal 22b for preventing air suction are installed on the left side of the lip seal 22a. ing.

On the other hand, in the left pneumatic part 2, there is a casing 30 fixed to the flange 5b of the main body 5 by a plurality of bolt nuts.
There is. A dish-shaped pneumatic piston 31 is slidably inserted into the casing 30 . Pneumatic piston 31
A pneumatic chamber 33 connected to a brake valve or a relay valve (both not shown) is located on the left side through a connection hole 32, and a groove 5c and hole 5d of the flange 5b are located on the right side.
Atmospheric chambers 34 communicating with the outside air are each partitioned. A part of the center 4 of the pneumatic piston 31 is welded to the plunger 11 so that the pneumatic piston 31 moves integrally with the plunger 11. It is biased to the left inactive position.

The operation of the booster 1 configured as described above is as follows.

When inactive, the piston 31-plunger 11 assembly is in the position shown due to the biasing force of the return spring 35. Therefore, the hydraulic chamber 12 has a recess 11a and a small hole 11.
1), void 18, passage 19° hole 7a, outer circumferential groove 7N),
The hole 5a and the joint 2o are sequentially connected to the hydraulic fluid reservoir, and the pressure is released.

On the other hand, during operation, compressed air is supplied into the pneumatic chamber 33, so that the pneumatic piston 31 moves to the right against the urging force of the return spring 35 due to the differential pressure with the atmospheric chamber 34.

Along with this, the plunger 11 also moves to the right, and its small hole 11b is located on the right side of the inner knob 9a of the lip seal 9, thereby cutting off communication between the hydraulic pressure chamber 12 and the hydraulic fluid reservoir. After this, when the plunger 11 moves further to the right, pressure is generated in the hydraulic pressure chamber 1.2, and this pressure is transmitted to the axle braking device and the brake starts to be applied.

When the desired brake is applied, when compressed air is discharged from the pneumatic chamber 33, the piston 31-plunger 1.
The assembly 1- is moved to the left by the biasing force of the return spring 35. This movement is relatively fast, so the hydraulic chamber 1
Negative pressure is temporarily generated within 2. This negative pressure deforms the inner lip 9a of the lip seal 9, causing the hydraulic fluid to flow into the passage 1.
The hydraulic pressure chamber 12 is replenished from the 9 and cavity 18 sides. After that, when the piston 31 and the plunger 11 are completely returned, the small hole 111) of the plunger 11 is again opened to the inner lip 9a.
The hydraulic pressure chamber 12 is connected to the cavity 18 by being located on the left side. As a result, the pressure within the hydraulic chamber 12 is released in communication with the hydraulic fluid reservoir, and excess hydraulic fluid returns to the hydraulic fluid reservoir.

(Problems to be Solved by the Invention) As described above, the booster 1 generates hydraulic pressure within the hydraulic pressure chamber 12 by moving the plunger 11.

This is supplied to the wheel brake device while being sealed by the lip seal 9. When hydraulic pressure is generated in the hydraulic pressure chamber 12, the lip seal 9 is pressed against the spacer 8 by the constant hydraulic pressure. It will be done. Therefore, the lip seal 9 has its base portion 9c pressed against the end surface of the spacer 7, and the base portion 9C
The communication portion between the and each lip 9a, 9b is a corner formed by the spacer 7 and the inner surface of the increased diameter portion 6, a gap between the two that is continuous to this corner, a space 18, and a passage that is continuous to this. 19, respectively. In such deformation, the former gap is not particularly used as a liquid passage, so by appropriately setting the specifications, it is possible to prevent deformation that would cause the lip seal to enter. It is possible to prevent the lip seal from being eaten away even after the process. However, since the latter cavity 18 and passage 19 are used as a passage connecting the hydraulic fluid reservoir and the hydraulic pressure chamber 12, they cannot be made small enough to prevent erosion. Therefore, after repeated operations, the connecting portion between the base portion 9C and the inner lip 9a is damaged, causing a problem that hydraulic pressure cannot be generated within the hydraulic pressure chamber 12.

Particularly, such a problem becomes significant when high pressure is generated during normal brake operation, and becomes a serious problem in the booster 1 used in a large vehicle.

Therefore, it is an object of the present invention to provide a technology that can effectively prevent such erosion in response to the fact that the sealing member is severely eaten away by the communication passage in a high pressure region. do.

(Means for Solving the Problems) In the present invention, a ring member that faces the opening of the passage and is slidably fitted to the outer periphery of the plunger is disposed on the low pressure side of the sealing member, and the ring member is provided on the low pressure side of the sealing member. A deformable member is provided on the outer periphery of the member, which can be elastically deformed by the acting force of the pressure of the hydraulic chamber received through the sealing member, and can form a gap that allows communication between the passage and the through hole by restoring deformation. ing.

(Function) If no pressure is generated in the hydraulic chamber, or even if pressure is generated, the pressure is low, the acting force received from the sealing member is small, so the deformable member is in a restoring deformed state, or Even if it deforms a little, the amount of deformation is not sufficient.
There is a gap that allows communication between the passage and the through hole. On the other hand, as the pressure inside the hydraulic chamber increases, the deformation of the deformable member increases,
It is deformed until the gap disappears. At this time, since the passage is closed by the ring member, the deformed deformed member does not enter the passage 6 Therefore, in the low pressure region, since the amount of deformation of the sealing member is small, no eating occurs, and furthermore, In the high pressure range, even if the sealing member receives hydraulic pressure, the gap on the low pressure side can be closed by the deformation of the deformable member, and there is no gap for the sealing member to enter and squeeze, regardless of the pressure level. No more getting eaten.

(Embodiment) Figure 1 is a sectional view of a main part showing an embodiment of the present invention, Figure 2 is a diagram showing its operating state, and Figure 3 is an enlarged view of the ring member in Figure 1.

This embodiment is characterized in that a ring member 40 is disposed between the sealing member 9 and the spacer 11, as will be clear from a comparison with FIG. 6 showing the conventional example. In addition, other points are functionally the same except for dimensions, so the same reference numerals are used.

The sliding member 40 includes a sliding member 41 made of synthetic resin and having a rectangular cross section, and a deformable member 42 made of rubber that is integrally provided on the outer periphery of the sliding member 41.
have or do. The sliding member 41 has a fairly small gap around the outer periphery of the plunger 11. In other words, depending on the pressure generated in the hydraulic pressure chamber 12, the sealing member 9 cannot enter, or even if it does, it may not be able to enter. Even though the amount is small, there is no effect of being eaten or an acceptable gap is formed.

However, this small gap does not adversely affect the sliding movement of the plunger/jar 11 itself. .

Further, the deformable member 42 has a shape in which the inner diameter side and the outer diameter side of a circular cross section are cut off, and is integrally molded and bonded to the outer peripheral surface of the sliding member 41. Deformable member 4
A large number of protrusions 43 are provided at intervals in the circumferential direction on the left and right spherical portions of 2. .

The ring member 40 is arranged at the end face portion of the sleeve 7.

As a result, one of the protrusions 43 of the deformable member 42 abuts the spacer 7 and the other abuts the base portion 9c of the sealing member 9. A continuous gap 45 is formed between the spacer 7 and the spacer 7. This gap 45 is
It communicates via a cavity 18 on the left side of the inner lip 9a with the small hole 11k) and with a passage 19, which communicates the hydraulic chamber 12 with the hydraulic fluid reservoir.

Now, by moving the plunger 11 to the right, the hydraulic chamber 1
When the pressure inside 2 increases, when the hydraulic pressure is low, the deformable member 42 hardly deforms, similar to the shape shown in FIG. The acting force acting on the member 4o increases; 1. As the gap between the left and right sides of the sliding member 41 becomes smaller, the gap 45 around the deformable member 42 gradually becomes smaller. Finally, as shown in FIG. 2, the deformation occurs so that all the surrounding gaps 45 disappear. In this state, the sealing member 9 has no gap where its low pressure side 1 is eaten, so
To reliably seal the pressure of a hydraulic chamber 12. Note that by appropriately setting the wall thickness of the deformable member 42 on the outer circumferential side, the force applied to the sliding member 41 inward in the radial direction is not so large, and therefore, the sliding resistance of the plunger 11 is unnecessary. You can avoid increasing it.

When the desired brake is applied or a pumping effect is obtained, the pressure in the hydraulic chamber 12 decreases, so the deformable member 42 restores deformation to secure the gap 45 and prevent the flow from the hydraulic fluid reservoir to the hydraulic chamber 12. Fluid replenishment is guaranteed.

In the above example, the left and right sides of the deformable member 42 are spherical, but it goes without saying that the deformable member 42 may have a tapered surface that expands outward as shown in FIG.

(Effects of the Invention) According to the present invention, by providing a spacer having a portion that deforms elastically and a portion that does not deform, it is possible to prevent the sealing member from being eaten away on the low pressure side while ensuring sufficient clearance for the passage. Therefore, durability and reliability can be improved.

[Brief explanation of drawings]

1 and 2 are views showing essential parts of an embodiment of the present invention, FIG. 3 is a view showing a cross-sectional shape of a ring member, and FIG. 4 is a view showing another embodiment of the invention. FIGS. 5 and 6 are diagrams showing conventional examples. 4... Cylinder hole, 5... Cylinder body, 9...
Lip seal (sealing member), 1o...Groove, 11...
・Plunger, 12... Hydraulic pressure chamber, 19... Passage, 3
3... Pneumatic chamber, 40... Ring member, 41... Sliding member, 42... Deformable member, 45... Gap.

Claims (1)

[Claims] 1. A cylinder body having a cylinder hole with one end closed and a groove for mounting a sealing member on the open end side, and a cylinder body that is fitted into the cylinder hole from the open end side through the sealing member to define a hydraulic chamber. a plunger having one end communicating with the hydraulic fluid reservoir and the other end opening into the low-pressure side of the groove; and a passage provided in the plunger, one end opening at the outer periphery of the plunger and the other end opening into the hydraulic pressure chamber. and a through hole that allows communication between the passage and the hydraulic pressure chamber, and when the opening of the through hole crosses the sealing member due to movement of the plunger,
In a plunger-type master cylinder configured to seal the hydraulic pressure chamber by blocking communication between the passage and the hydraulic pressure chamber, the plunger is slidably fitted to the outer periphery of the plunger facing the opening of the passage. A ring member is disposed on the low-pressure side of the sealing member, and is elastically deformable by a force acting on the outer periphery of the ring member due to the pressure of the hydraulic pressure chamber received via the sealing member, and the ring member is elastically deformable by the force exerted on the outer periphery of the ring member by the pressure of the hydraulic pressure chamber, and is connected to the passage by restoring deformation. A plunger type master cylinder is provided with a deformable member that can form a gap that allows communication with the through hole.