JPH07301273A - Seal ring structure in free piston - Google Patents

Abstract

PURPOSE:To optimize the utilization of an accumulator to be installed for a hydraulic guaranty of pulsation prevention or the like in a hydraulic control circuit by checking any outgassing out of a seal ring part effectively. CONSTITUTION:This seal ring structure is made up of coupling an oil chamber side splitter 2 and a gas chamber side splitter 3, where a free piston 1 being slidably housed in a housing H to constitute an accumulator and partitioning off an oil chamber R and a gas chamber G in this housing H, is split and formed, while being composed of setting up a seal ring 10 in a ring groove 4 to be formed in time of being coupled together. In this constitution, the seal ring 10 is made up of having an insert ring 11 being formed in ring form showing an almost L-shaped section inside, while this insert ring 11 is positioned at the side adjacent to a bottom surface 4a of the ring groove 4 and at the side adjacent to a gas chamber side 4b of the ring groove 4 in the seal ring 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seal ring structure in a free piston, and more particularly to a free accumulator used for ensuring hydraulic pressure such as accumulated pressure and shock pressure in a hydraulic control circuit and absorbing pulsation. The present invention relates to improvement of a seal ring structure in a piston.

[0002]

2. Description of the Related Art As is well known, accumulators used for ensuring hydraulic pressure such as accumulated pressure in a hydraulic control circuit, damping of impact pressure, and pulsation absorption include a bladder type and a free piston type. In the bladder type, since the bladder made of a rubber film allows the gas to pass therethrough, there is a problem in that so-called gas escape due to gas permeation is caused during long-term use.

On the other hand, it is said that the free piston type does not cause gas outflow as much as the bladder type does.

However, for example, a free piston P in an accumulator having a structure as shown in FIG. 6, that is, a housing H is slidably housed in the housing H to define a gas chamber G and an oil chamber R therein. Free piston P
In this case, the outer circumference of the free piston P and the housing H
It has been pointed out that gas leakage due to gas leakage is caused at the seal ring S portion made of a rubber material that is distributed between the inner periphery of the seal ring and the inner periphery of the seal.

That is, looking at the seal ring S portion in detail, as shown by arrows a and b in FIG. 7, between the outer circumference of the seal ring S and the inner circumference of the housing H and the seal ring S. Gas leakage due to gas leakage is caused by two routes between the inner circumference and the outer circumference of the free piston P, especially when the oil chamber R side has a negative pressure than the gas chamber G side.

When the free piston does not slide and is in an inoperative state, and the pressures on the oil chamber R side and the gas chamber G side are balanced, the seal ring S itself is the same as in the case of the bladder described above. Will allow gas to permeate, which will lead to outgassing, albeit in a small amount.

As a result, the gas pressure in the gas chamber G becomes insufficient, so that the predetermined accumulator function is not exerted, and the leaked gas is mixed in the oil, so that the hydraulic pressure control circuit is provided. Therefore, the hydraulic equipment and the like installed in the above will cause problems such as erosion and adiabatic compression.

The present invention was made in view of the above circumstances, and an object thereof is to effectively prevent gas leakage from the seal ring portion and gas escape due to gas permeation, (EN) Provided is a seal ring structure in a free piston, which is most suitable for use in an accumulator arranged to secure hydraulic pressure such as accumulated pressure in a hydraulic control circuit, damping of impact pressure, and pulsation absorption.

[0009]

In order to achieve the above object, the structure of the present invention is slidably housed in a housing constituting an accumulator, and a gas chamber and an oil chamber are housed in the housing. A seal ring in a free piston having a partitioning free piston and a seal ring made of a rubber material, which is arranged in an annular groove formed on the outer circumference of the free piston and the outer circumference of which is in sliding contact with the inner circumference of the housing. In the structure, a free piston is formed by connecting an oil chamber side divided body and a gas chamber side divided body, which are separately formed, and a seal ring is arranged in an annular groove formed at the time of the connection. The ring has an insert ring formed in an annular shape having a substantially L-shaped cross section inside, and the insert ring is adjacent to the bottom surface of the annular groove in the seal ring. And the composed position determined on the side adjacent to the gas chamber side of the annular groove.

[0010]

Therefore, the seal ring made of a rubber material has a margin to be deformed on the inner peripheral side and the peripheral surface side of the gas chamber side due to the distribution of the insert ring, and the outer periphery where the insert ring is not present. There is room to deform only on the side.

As a result, the seal ring arranged in the annular groove is always brought into close contact with the inner periphery of the seal ring without any allowance for deformation to the bottom surface of the annular groove, and gas due to gas leakage through the close contact portion. Prevent the omission.

Further, the seal ring disposed in the annular groove is always in close contact with the annular chamber when the peripheral surface on the gas chamber side is adjacent to the gas chamber side surface of the annular groove. Prevents gas escape due to gas leakage through close contact parts.

Further, the seal ring disposed in the annular groove is slidably contacted with the inner circumference of the housing while leaving a margin for deformation on the outer circumference side, and gas leakage which may be caused through the slidable contact portion is caused. It allows only gas escape due to the above, and allows only gas permeation which may be caused in the outer peripheral portion where the insert ring is not present.

Incidentally, when the free piston is in a divided state, the seal ring is fitted in a predetermined position, and thereafter, each side divided body is joined to form the free piston.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the drawings. However, even in the seal ring structure in the free piston according to the embodiment of the present invention, an accumulator is constructed in the same manner as the above-mentioned conventional example. The outer periphery of a seal ring slidably accommodated in the housing and arranged in an annular groove formed on the outer periphery of a free piston that divides a gas chamber and an oil chamber into the housing slides on the inner periphery of the housing. It is configured to be touched.

Therefore, where the structure is the same as that of the above-mentioned conventional example, only the same reference numerals are given in the drawings, and the detailed description thereof is omitted, and the following is a feature of the present invention. The explanation will focus on this.

That is, as shown in FIG. 1, the free piston 1 according to the present invention is formed by connecting an oil chamber side divided body 2 and a gas chamber side divided body 3 which are formed separately, and the free piston 1 is also formed. A seal ring 1 is formed in an annular groove 4 that is sometimes formed.
0 is distributed.

The seal ring 10 is made of a rubber material, and has an annular insert ring 11 having a substantially L-shaped cross section, and the insert ring 11 has an annular shape inside the seal ring 10. It is supposed that the groove 4 is positioned on the side adjacent to the bottom surface 4a and on the side of the annular groove 4 adjacent to the gas chamber side surface 4b.

In this embodiment, on the outer circumference of the free piston 1, there is a wear ring 6 housed in a pair of annular grooves 5 formed so as to sandwich the above-mentioned annular groove 4. However, the provision of the wear ring 6 may be omitted.

However, in the case where the wear ring 6 is provided, the free piston P is slid while it is in the housing H.
This is advantageous in that it can be prevented in advance that the inner peripheral surface of the housing H is tilted inward and the inner peripheral surface of the housing H is so-called kazil.

When the wear ring 6 is provided only at one place, it is necessary to increase the effective width of the wear ring 6, which increases the length of the free piston P in the stroke direction. Compared with the case where the wear ring 6 is omitted, it is advantageous in that so-called galling can be prevented in advance.

The oil chamber side divided body 2 is a gas chamber side divided body 3.
Is formed so as to be press-fitted into the gas chamber. And a cylindrical connecting portion 2b extending to the G side.

On the other hand, the gas chamber side divided body 3 has an annular partition wall portion 3a formed to have a diameter slightly smaller than the inner diameter of the housing H, and is connected to the partition wall portion 3a to be connected to the oil chamber R side. And a connecting portion 3b which extends in a tubular shape and into which the connecting portion 2b of the oil chamber side divided body 2 is fitted.

When the connecting portion 2b of the oil chamber side divided body 2 is press-fitted so as to be inserted into the connecting portion 3b of the gas chamber side divided body 3, the free piston 1 is formed and the oil chamber is formed. The annular groove 4 is formed by the outer circumference of the partition wall 2a of the side divided body 2 and the outer circumferences of the partition wall 3a and the connecting portion 3b of the gas chamber side divided body 3.

Incidentally, in the illustrated example, the oil chamber side divided body 2
The inner circumference of the connecting portion 2b at is to form a space 7 which is a part of the oil chamber R, so that the volume of the oil chamber R is increased and the weight of the free piston 1 itself is reduced.

On the other hand, the seal ring 10 according to the present invention.
As described above, is made of a rubber material like the conventional seal ring of this type, and is formed to have an X-shaped cross section in the illustrated example.

When the seal ring 10 is formed to have an X-shaped cross section as in the illustrated example, there are two sliding contact points with the housing H, which improves the so-called sealing performance. Become.

The insert ring 11 is conventionally made of
It is similar to what is called insert metal, and it can be used for SPCC, SPCD, SPCE or SPHC,
The rubber material which is made of rolled steel such as SPHD and SPHE and constitutes the seal ring 10 is vulcanized and adhered.

By the way, the insert ring 11 in this embodiment is formed in an annular shape having a substantially L-shaped cross section, and when it is positioned in the seal ring 10, it is adjacent to the bottom surface 4a of the annular groove 4. It is supposed that the side and the side of the annular groove 4 adjacent to the side surface 4b on the gas chamber G side are positioned, but this brings about the following effects.

That is, first, it goes without saying that the seal ring 10 tends to prevent the expansion of the inner diameter of the seal ring 10 due to the distribution of the insert ring 11, but on the inner peripheral side and the gas chamber G side. The amount of deformation on the peripheral surface side becomes extremely small.

On the other hand, the seal ring 10 has a margin to be deformed only on the outer peripheral side where the insert ring 11 is not present.

Therefore, the seal ring 10 arranged in the annular groove 4 is always brought into close contact with the bottom surface 4a of the annular groove 4 due to the arrangement of the insert ring 11 without being deformed. Therefore, the gas leakage through the close portion is absolutely prevented.

The seal ring 10 arranged in the annular groove 4 has the insert ring 11 arranged when the peripheral surface on the gas chamber G side is adjacent to the gas chamber side surface 4a of the annular groove 4. , It will always be in close contact with each other without deformation,
Therefore, gas leakage through the close contact area is absolutely prevented.

The outer periphery of the seal ring 10 disposed in the annular groove 4 is slidably contacted with the inner periphery of the housing H with a margin of deformation because the insert ring 11 is not present. Housing H
In addition to having a predetermined slidability with respect to the above, as shown by the arrow a in FIG. 2, only gas leakage that may be caused via the sliding contact portion is allowed.

At this time, in the illustrated example, the seal ring 10
Is formed so as to have an X-shaped cross section and the so-called sealing property is improved, so that the above-mentioned gas leakage phenomenon is exhibited with a tendency to be suppressed.

Further, as shown in the schematic view of FIG. 3, the seal ring 10 arranged in the annular groove 4 has its outer peripheral portion where the insert ring 11 is not present (A portion hatched in FIG. 3). Will only allow gas permeation that may be introduced in.

At this time, in the illustrated example, the seal ring 10 is formed so as to have an X-shaped cross section, and there are two rubber portions connected in series, so that the above gas permeation phenomenon is suppressed. It will be expressed under a tendency.

Therefore, the seal ring 1 according to this embodiment is
0 is the same as this type of conventional seal ring,
Compared to not being able to prevent gas leakage not only on the outer peripheral side but also on the inner peripheral side, only a very small amount of gas leakage on the outer peripheral side is allowed.

Further, the seal ring 10 according to this embodiment.
Therefore, in the conventional seal ring of this type, extremely small gas permeation is allowed as compared with the case where the seal ring itself allows gas permeation over the entire area.

As a result, the amount of gas leaked from the gas chamber G to the oil chamber R and the amount of gas released due to gas permeation is greatly reduced,
Therefore, it becomes difficult for the gas pressure in the gas chamber G to be insufficient at an early stage, and the problem that the escaped gas is mixed in the oil is less likely to occur.

In the present invention, the above seal ring 10 is fitted in a predetermined position when the free piston 1 is in a divided state.

That is, in the illustrated example, the oil chamber side divided body 2
3b in the gas chamber side divided body 3 before being joined
It is said that the seal ring 10 is fitted to a predetermined position by interposing the seal ring 10 on the outer periphery of the.

When the oil chamber side divided body 2 is joined to the gas chamber side divided body 3 in which the seal ring 10 is interposed to form the free piston 1, the seal ring 10 is arranged in the annular groove 4. It will be in the state of being.

Incidentally, since the seal ring 10 has the insert ring 11 inside and is set so as to tend to prevent the expansion of the diameter, the work of interposing the outer periphery of the connecting portion 3b is not performed. This is executed by using an appropriate jig.

FIG. 4 shows another embodiment for forming the free piston 1, and in this embodiment, the side division bodies 2 and 3 are coupled by screwing.

Therefore, in the case of this embodiment, it is advantageous in that the connection state of the respective side divided bodies 2, 3 is ensured as compared with the above-mentioned embodiment.

Incidentally, in the illustrated example, the oil chamber side divided body 2
The thread 2c formed on the outer circumference of the partition wall 2a in the above-mentioned is a thread 3c formed on the inner circumference of the connecting portion 3b in the gas chamber side divided body 3.
It is said that the connected state of each of the side divided bodies 2 and 3 is realized by screwing into.

FIG. 5 shows another embodiment of the seal ring 10, in which the seal ring 10 is used.
Are formed to have an O-shaped cross section.

Therefore, in the case of this embodiment, although it depends on the size of the slidable contact length, there is only one slidable contact point as compared with the case of the above-mentioned embodiment, and the slidability is improved. Is advantageous in that it can be intended to improve

The seal ring 10 has, of course, the insert ring 11, and the insert ring 11 is formed in an annular shape having a substantially L-shaped cross section, as in the above-mentioned embodiment. This is the seal ring 1
When it is positioned within 0, it is supposed to be positioned on the side adjacent to the bottom surface 4a of the annular groove 4 and on the side adjacent to the side surface 4b of the annular groove 4 on the gas chamber G side.

In the illustrated example, the insert ring 1
One end, which is the left end in FIG. 1, is bent inward, which is the lower end in the drawing, so that a large shearing force is not concentrated on the outer peripheral portion of the seal ring 10.

Therefore, also in this embodiment, similarly to the above-mentioned embodiments, the seal ring 10 arranged in the annular groove 4 is provided on the inner peripheral side and the peripheral surface side on the gas chamber G side. While preventing the gas leakage due to the gas leakage, only the gas leakage through the outer periphery and the gas leakage due to the gas permeation in the outer peripheral portion are allowed.

The above description is that the seal ring 10 in the present invention effectively prevents gas leakage due to gas leakage and gas permeation. According to the present invention, the seal ring 10 is provided in the annular groove 4. The inner periphery of the annular groove 4 is closely attached to the bottom surface 4a of the annular groove 4, and the peripheral surface of the gas chamber G side is also closely attached to the gas chamber side surface 4b of the annular groove 4. Therefore, the seal ring 10 is fixedly arranged on the outer circumference of the free piston 1.

As a result, when the free piston 1 slides, the seal ring 10 always starts to slide synchronously, and the seal ring S may move in the annular groove. Compared with the above, it is advantageous in that the so-called sliding delay in the free piston 1 is not caused.

[0055]

As described above, according to the present invention, the seal ring made of a rubber material is disposed in the annular groove formed on the outer circumference of the free piston and the outer circumference of the free piston makes sliding contact with the inner circumference of the housing. While the insert ring is distributed, there is no room to deform on the inner peripheral side and the peripheral surface side of the gas chamber side, while there is room to deform only on the outer peripheral side where the insert ring is not present. Therefore, while preventing the gas leakage due to gas leakage and gas permeation on the inner peripheral side and the peripheral surface side of the gas chamber side, only the gas leakage on the outer peripheral side and the gas leakage due to gas permeation in the outer peripheral portion are allowed. Therefore, there is an advantage that the amount of gas escaped from the gas chamber can be greatly reduced.

As a result, according to the present invention, the amount of gas escaped from the gas chamber to the oil chamber is greatly reduced, and therefore, insufficient gas pressure in the gas chamber is less likely to occur at an early stage, and a predetermined accumulator function is provided. It has the advantage that it can be maintained permanently.

Further, according to the present invention, the amount of gas mixed in the oil that escapes from the gas chamber is greatly reduced, so that problems such as erosion and adiabatic compression occur in hydraulic equipment and the like arranged in the hydraulic control circuit. There is an advantage that it is hard to be done.

Further, according to the present invention, since the seal ring is distributed around the outer periphery of the free piston in a fixed state, the seal ring may move in the annular groove as compared with the conventional free piston. Then, there is an advantage that so-called sliding delay is not caused in the free piston.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an arrangement state of a free piston in an accumulator according to an embodiment of the present invention.

FIG. 2 is a partially enlarged vertical sectional view of FIG.

FIG. 3 is a schematic view of a seal ring in an installed state.

FIG. 4 is a partially enlarged vertical sectional view showing another embodiment of the free piston.

FIG. 5 is a partially enlarged vertical sectional view showing another embodiment of the seal ring.

FIG. 6 is a front view showing a partially broken accumulator as a conventional example.

FIG. 7 is a partially enlarged vertical sectional view showing a seal ring as a conventional example.

[Explanation of symbols]

 1 Free Piston 2 Oil Chamber Side Divided Body 3 Gas Chamber Side Divided Body 4 Annular Groove 4a Bottom 4b Gas Chamber Side 10 Seal Ring 11 Insert Ring H Housing G Gas Chamber R Oil Chamber

Claims (1)

[Claims] 1. A free piston, which is slidably accommodated in a housing constituting an accumulator and defines a gas chamber and an oil chamber in the housing, and an annular groove formed on the outer circumference of the free piston. A seal ring made of a rubber material, the outer periphery of which is in sliding contact with the inner periphery of the housing, and a seal ring structure in a free piston, in which the free piston is divided into an oil chamber side divided body and a gas chamber side A seal ring is formed by connecting the split body and is disposed in an annular groove formed at the time of the connection, and the seal ring has an annular insert ring having a substantially L-shaped cross section. And the insert ring is positioned in the seal ring on the side adjacent to the bottom surface of the annular groove and on the side adjacent to the gas chamber side surface of the annular groove. Seal ring structure in free piston