JP2000186701A - Piston-type accumulator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a durability by surely preventing entering water and dust from a degassing hole while assuring degassing property from the degassing hole. SOLUTION: This piston type accumulator comprises an outer case (a cylinder 2, a housing 3), a piston 6 having a ring shape recess 6a and dividing a gas chamber 13 from a hydraulic fluid chamber 4, gas seal members (O rings, 9 and 10), a hydraulic fluid seal member (O ring 11), and a degassing chamber 7. A degassing hole 2d which communicates the degassing chamber 7 with an outside is provided in the outer case, and an outer opening of the degassing hole 2d has a check valve part 5a having a predetermined valve opening pressure and is covered with a cover 5 formed of a material of gas permeability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piston type accumulator for slidably fitting a piston in an outer case and accumulating hydraulic fluid.

[0002]

2. Description of the Related Art In a control device for a vehicle or the like using hydraulic pressure, for example, an anti-lock brake device, control is performed by using a hydraulic pressure supplied from a pump as a hydraulic pressure source. When the flow rate of the working fluid to be used is large, the supply flow rate from the pump may be temporarily insufficient with respect to the consumption flow rate, and the supply hydraulic pressure may temporarily decrease.
Also in this case, it is necessary to accumulate the hydraulic fluid supplied to the control circuit at a high pressure in order to maintain the supply hydraulic pressure at a predetermined pressure suitable for control as much as possible. For this reason, an accumulator is often used. As a conventional piston type accumulator of this type, for example, there is one described in Japanese Patent Application Laid-Open No. 8-82901. This is an outer case,
A piston having an annular recess at an axially central portion of the outer periphery and slidably fitted in the outer case and partitioning the outer case into a gas chamber and a hydraulic fluid chamber; A gas seal member disposed on the side of the piston, a hydraulic fluid seal member disposed closer to the hydraulic fluid chamber than the annular concave portion on the outer periphery of the piston, a gas seal member, a hydraulic fluid seal member, an annular concave portion, and an inner surface of the outer case. The outer case is provided with a gas vent hole communicating the gas vent chamber with the outside.

[0003] This gas vent hole is necessary for the following reasons. That is, the gas seal member seals gas (gas), and the working fluid seal member seals liquid. Here, among materials used when forming each seal member, those having excellent sealing properties for both gas and liquid are extremely rare, and furthermore, when disposed on a reciprocating sliding piston. It is difficult to satisfy durability at the same time. Therefore, a material having low gas permeability suitable for gas sealing (such as acrylonitrile butadiene rubber) is used for the gas seal member, and the hydraulic fluid seal member has excellent gas permeability and excellent sealing properties for brake fluid and the like. It is conceivable to improve the sealing performance of both gas and liquid by using a material (for example, ethylene propylene rubber or the like). However, as for the gas seal member, even if a material suitable for a gas seal having low gas permeability is used, the amount of gas permeating through the material cannot be reduced to zero. If the gas permeating from the gas seal member enters the working fluid chamber side, the gas will enter the control circuit, which may cause a delay in control operation and reduce the responsiveness of the device. Therefore, in order to prevent the inevitably present permeated gas from entering the working fluid chamber side, a vent hole is provided to discharge the permeated gas to the outside.

[0004]

However, the opening of the gas vent hole to the outside is not closed and is exposed to the outside. Therefore, there is a problem that water, dust, and the like enter the outer case from the outside, reduce the durability of the gas seal member and the working fluid seal member, and cause malfunction.

[0005] Further, the position and the direction of the gas vent hole are changed with water,
Even if it is arranged in a position and a direction in which dust and the like hardly invade, it is not possible to reliably prevent such intrusion.

Therefore, the present invention provides a piston type accumulator which can reliably prevent gas, water and the like from entering from a gas vent hole and improve durability while ensuring gas vent performance from the gas vent hole. To provide a technical issue.

[0007]

According to a first aspect of the present invention, there is provided an outer case having an outer case, an annular recess at an axially central portion of an outer periphery, and a sliding member inside the outer case. A piston that is movably fitted and partitions the inside of the outer case into a gas chamber and a working fluid chamber, a gas seal member disposed on the gas chamber side from the annular concave portion on the outer periphery of the piston, A gas release chamber formed by a hydraulic fluid seal member disposed on the hydraulic fluid chamber side of the annular concave portion on the outer periphery of the piston, the gas seal member, the hydraulic fluid seal member, the annular concave portion, and the inner surface of the outer case. Wherein the outer case is provided with a gas vent hole communicating the gas vent chamber with the outside, and the external opening of the gas vent hole has a check valve portion having a predetermined valve opening pressure. Both were a piston type accumulator, characterized in that is covered with a cover which is formed by gas permeable material.

That is, according to the first aspect of the present invention, since the outer opening of the gas vent hole provided in the outer case is covered with the cover, it is possible to reliably prevent water, dust and the like from entering from the outside. Can be.

Further, since the check valve portion having a predetermined valve opening pressure is provided on the cover, when the gas permeating the gas seal member and accumulated in the gas venting chamber reaches the predetermined valve opening pressure, the check valve is opened. Is activated and the gas can be released to the outside. This check valve portion is a one-way valve that allows passage from the degassing chamber to the outside but does not permit passage from the outside to the degassing chamber, and the pressure of the gas in the degassing chamber reaches a predetermined valve opening pressure. When it has not reached, since the valve is closed, there is no possibility that water, dust and the like may enter from outside. In addition, when the pressure of the gas in the degassing chamber has reached a predetermined valve opening pressure and the valve is open, there is a flow of gas from the degassing chamber to the outside. There is no danger of dust and the like entering.

Further, since the gas permeable material is adopted as the material of the cover, even when the pressure of the gas in the gas release chamber does not reach the predetermined valve opening pressure and the valve is closed, the gas release chamber is closed. This gas can be released to the outside by positively permeating the inside of the cover material.

As described above, according to the first aspect of the present invention, the piston type accumulator which can surely prevent water, dust and the like from entering the gas vent hole while ensuring the gas vent performance from the gas vent hole. Can be provided.

According to a second aspect of the present invention, in the first aspect, the cover is formed of an elastic body, and the check valve portion of the cover is formed by a cut formed in the cover itself. Features. In this way, by making a cut in the cover itself formed of the elastic body, by utilizing the restoring force of the elastic body, the function of the above-described check valve portion, that is, one-way having a predetermined valve opening pressure, It is possible to exhibit the function of a valve. Specifically, when the gas pressure in the degassing chamber does not reach the predetermined valve opening pressure, the mating surface of the cut portion of the cover is closed due to the restoring force of the cover itself, and the gas pressure in the degassing chamber becomes the predetermined pressure. When the valve opening pressure reaches the above, the mating surface of the cut portion of the cover receives gas pressure and opens by elastic deformation, whereby the function of the check valve portion can be exhibited.

Further, since the check valve portion can be formed only by making a cut in a part of the cover itself, it is not necessary to add a new part for forming the check valve portion, and the cost is reduced by a simple structure. Can be provided.

According to a third aspect of the present invention, there is provided the first or second aspect.
Wherein the cover is air-tightly wound around the outer periphery of the outer case. Thereby, the assembly of the cover is completed only by winding the cover around the outer periphery of the outer case, so that it is possible to reduce the cost by improving the assemblability.

According to a fourth aspect of the present invention, in the first to third aspects, the material of the cover is an ethylene propylene rubber material. Since the ethylene propylene rubber material is easily available and inexpensive, by using this material for the cover, the cost of the cover alone can be reduced.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view of a piston type accumulator according to one embodiment of the present invention. In FIG. 1, the left half shows the state where the piston 6 is moving to the lowest position within the slidable range, and the right half shows the state where the piston 6 is moving to the highest position within the slidable range. ing. FIG. 2 shows a portion A (a cover 5 portion) in FIG.
FIG. First, the mechanical configuration of the piston type accumulator 1 will be described with reference to FIGS. 1 and 2.

In FIG. 1, reference numeral 2 denotes a cylindrical cylinder having a bottom, in which a piston 6 is slidably fitted. Opening of cylinder 2 (lower in FIG. 1)
Is closed by the housing 3 and the cylinder 2
And the housing 3 constitute an outer case. The housing 3 is screwed to the cylinder 2 by a screw portion 3 b provided on the housing 3 and a male screw portion 2 a provided on the cylinder 2.
c is integrally fixed by caulking the flange portion 2b of the cylinder 2.

A gas chamber 13 is formed above the piston 6 in FIG. 1, and a gas such as nitrogen gas is sealed in the gas chamber 13 at a high pressure. On the other hand, a hydraulic fluid chamber 4 is formed below the piston 6 in FIG.
A working fluid such as a brake fluid is stored therein. The working fluid pressure chamber 4 communicates with a port 3aa provided in a plug 3a formed in the housing 3, and
a is liquid-tightly connected to a pipe (not shown) connecting a discharge side of a pump for generating hydraulic pressure and a hydraulic circuit such as a braking device, and the hydraulic fluid in the hydraulic fluid chamber 4 is connected to a port 3aa. It is used for driving a braking device or the like of the vehicle through the like.

The piston 6 has an annular recess 6a at the center of the outer periphery in the axial direction (vertical direction in FIG. 1), and O-rings 9 and 10 (gas seal members) on the gas chamber 13 side from the outer periphery of the annular recess 6a. Is provided, and hermetically seals the gas chamber 13. On the other hand, an O-ring 11 (hydraulic fluid seal member) is also disposed on the hydraulic fluid chamber 4 side from the outer annular recess 6 a, and an O-ring 12 disposed on a fitting surface of the cylinder 2 and the housing 3. In cooperation with this, the working fluid chamber 4 is sealed in a liquid-tight manner. The O-rings 9 and 11 and the annular recess 6a
A gas venting chamber 7 is formed on the inner surface of the cylinder 2. The piston 6 is provided with a cylindrical groove 6b at the upper part in FIG. 1 so that the piston 6 can secure a certain volume in the gas chamber 13 even when the piston 6 moves upward in FIG. Tuning of gas spring constant.

The O-rings 9 and 10 are made of a hydrogenated acrylonitrile-butadiene rubber, which is a material having a high sealing property so that high-pressure gas does not pass through as much as possible and having a low gas permeability.
It is desirable to use butyl rubber or acrylonitrile butadiene rubber. The O-ring 9 functions as a backup O-ring for the O-ring 10 and further improves the sealing performance of the gas in the gas chamber 13. On the other hand, it is desirable that the O-rings 11 and 12 use ethylene propylene rubber (hereinafter, referred to as EPDM) or styrene rubber, which is a liquid-sealing member that is excellent in blocking performance of brake fluid and the like.

The cylinder 2 is provided with a gas vent hole 2d. The gas vent hole 2d is penetrated and the cylinder 2
The outside and the inside of the device communicate. The internal opening of the gas vent hole 2d is provided at a position always exposed to the gas vent chamber 7 even if the piston 6 slides up and down in FIG. 1 within the slidable range. The external opening 2 d is covered with a cover 5 wound around the outer periphery of the cylinder 2.

The cover 5 is made of an elastic material such as EPDM, which is excellent in blocking performance of brake fluid and the like, but has a low gas sealing property and a high gas permeability. Four ring-shaped lips 5b are provided on the inner surface of the cover 5 (see FIG. 2), and the lip 5b and the outer peripheral surface of the cylinder 2 are sealed to prevent intrusion of water, dust and the like from the outside. Preventing. A check valve portion 5a is formed integrally with the cover 5, and the check valve portion 5a has a slit 5c (cut) penetrating in the thickness direction (the left-right direction in FIG. 2).
Is provided. The mating surface of the slit 5c is normally closed by the restoring force of a material that is an elastic body.

A bleeder hole 2c for filling gas is provided at the upper part of the cylinder 2 in FIG.
The bleeder hole 2c is hermetically closed by a bleeder plug 8.

The operation of the piston type accumulator 1 configured as described above will be described below. As aforementioned,
In a control device, for example, an anti-lock brake device, control is performed using hydraulic pressure supplied from a pump, which is a hydraulic pressure source (not shown). This hydraulic pressure is transmitted to the hydraulic fluid chamber 4 via the port 3aa. . The hydraulic pressure transmitted to the hydraulic fluid chamber 4 is normally a predetermined high pressure suitable for control, and the high pressure causes the piston 6 to receive an upward force in FIG. And move upward. The state moved to the uppermost position is shown in the right half of FIG. In this state, when the flow rate of the working fluid used for control such as complicated control is large, the supply flow rate from the pump is temporarily insufficient with respect to the consumption flow rate, and the pressure in the working fluid chamber 4 is temporarily reduced. In some cases. In this case, the upward force received by the piston 6 due to the oil pressure in the hydraulic fluid chamber 4 decreases, so that the downward force received by the gas pressure in the gas chamber 13 becomes dominant, and the piston 6 moves downward. I do. The state in which the piston 6 has moved to the lowest position is shown in the left half of FIG. Due to the downward movement of the piston 6, the flow rate flowing out of the port 3aa is used for auxiliary control, and the pressure drop of the supply hydraulic pressure can be suppressed as much as possible.

Next, the operation of the cover 5, which is a feature of the present invention, will be described with reference to FIGS. As described above, the gas in the gas chamber 13 is sealed in a liquid-tight manner by the O-rings 9 and 10 (gas seal members), but the amount of gas permeating through the material of the O-rings 9 and 10 is not zero. Therefore, the O-ring 1
0, it moves to the degassing chamber 7 via the O-ring 9. The gas that has moved to the gas venting chamber 7 moves to the inner peripheral surface side of the cover 5 via the gas vent hole 2d formed in the cylinder 2.
As described above, the check valve portion 5a is integrally formed on the cover 5, and the check valve portion 5a is provided in the thickness direction (FIG. 2).
In this case, a slit 5c (cut) penetrating in the left-right direction is provided. The mating surface of the slit 5c is normally closed by the restoring force of a material that is an elastic body, thereby preventing intrusion of water, dust, and the like from the outside. But,
When the amount of gas permeating the O-rings 10 and 9 increases with the passage of time and the pressure in the degassing chamber 7 reaches a predetermined valve opening pressure, the mating surface of the slit 5c receives the gas pressure. Since the gas is opened by elastic deformation, the gas in the gas release chamber 7 is discharged to the outside from between the mating surfaces of the slits 5c. The gas flow at this time is indicated by the arrow in FIG.

Since the cover 5 is made of a gas permeable EPDM material or the like, the pressure in the gas venting chamber 7 does not reach the predetermined valve opening pressure, and the mating surface of the slit 5c is reduced. Even in the closed state, the gas in the degassing chamber 7 can be released to the outside by actively transmitting the inside of the cover material.

As described above, if the book cover 5 is adopted,
It is possible to provide the piston type accumulator 1 that can reliably prevent the intrusion of water, dust, and the like from the outside while ensuring the gas releasing property from the gas releasing hole 2d.

[0029]

According to the present invention, since the external opening of the gas vent hole provided in the outer case is covered with the cover, intrusion of water, dust and the like from the outside can be surely prevented.

Since the cover is provided with a check valve portion having a predetermined valve opening pressure, when the gas permeating the gas seal member and accumulated in the gas venting chamber reaches the predetermined valve opening pressure, the check valve is opened. Is activated and the gas can be released to the outside. When the pressure of the gas in the degassing chamber has not reached the predetermined valve opening pressure, the check valve is closed, so that there is no possibility that water, dust and the like enter from the outside.

Further, since the gas permeable material is adopted as the material of the cover, even when the pressure of the gas in the gas vent chamber does not reach the predetermined valve opening pressure and the valve is closed, the gas vent chamber is closed. This gas can be released to the outside by positively permeating the inside of the cover material.

Therefore, according to the present invention, it is possible to reliably prevent the intrusion of water, dust and the like from the gas vent hole and secure the gas vent performance from the gas vent hole, thereby improving the durability. It is possible to provide a simple piston type accumulator.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a piston type accumulator according to one embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a portion A in FIG.

[Explanation of symbols]

 2 Cylinder (outer case) 2d Gas vent hole 3 Housing (outer case) 4 Hydraulic fluid chamber 5 Cover 5a Check valve section, 5c Slit (cut) 6 Piston 6a Annular recess 7 Gas vent chamber 9, 10 O-ring (gas seal member) ) 11 O-ring (Hydraulic fluid seal member) 13 Gas chamber

Claims (4)

[Claims] 1. An outer case having an annular recess at an axially central portion of an outer periphery is slidably fitted in the outer case, and the inside of the outer case is divided into a gas chamber and a hydraulic fluid chamber. A piston to be partitioned, a gas seal member disposed on the gas chamber side from the annular concave portion on the outer periphery of the piston, and a hydraulic fluid seal member disposed on the hydraulic fluid chamber side from the annular concave portion on the outer periphery of the piston. A gas venting chamber formed by the gas seal member, the working fluid seal member, the annular concave portion, and the inner surface of the outer case, wherein the outer case has a gas that communicates the gas vent chamber with the outside. A vent hole is provided, and an external opening of the vent hole has a check valve portion having a predetermined valve opening pressure and is covered with a cover formed of a gas-permeable material. Piston-type accumulator to. 2. The piston type accumulator according to claim 1, wherein the cover is formed of an elastic body, and the check valve portion of the cover is formed by a cut formed in the cover itself. 3. The piston type accumulator according to claim 1, wherein the cover is hermetically wound around an outer periphery of the outer case. 4. A piston type accumulator according to claim 1, wherein said cover is made of ethylene propylene rubber.