JP2008121846A - Backup ring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backup ring capable of maintaining sufficient sealing performance by certainly preventing projection of a seal member according to the backup ring. <P>SOLUTION: The backup ring made of a resin material is used with the seal member made of a rubber-like elastic material for sealing a clearance between relative motion members, and prevents the seal member from being projected to the clearance between the relative motion members by a pressure of a fluid to be sealed. The backup ring is provided with a constitution provided with a curved surface recessed toward the seal member. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a backup ring.
The present invention also relates to a backup ring useful in conjunction with a seal member.
Furthermore, the present invention relates to a backup ring that reliably prevents leakage between relative members of hydraulic shock absorbers such as reciprocating construction machines, cylinders for general machines, and shock absorbers.

  Furthermore, the present invention is attached to either one of the fixed portion and the moving portion that move relative to each other, and effectively prevents the intrusion of foreign matters such as muddy water from the outside to the inside and the leakage of oil and the like from the inside to the outside. It relates to a backup ring that is useful when used with packing.

Conventionally, the packing backup ring is disposed between the packing 100 and the wall surface 111 of the groove 110 provided on one side between the relative motion members A and B as shown in FIG.
When the packing 100 is pressurized, the backup ring 200 compresses and deforms in the axial direction and expands in the radial direction, as shown in FIG.
As a result, the gap Z existing between the inner and outer peripheral surfaces of the backup ring 200 and the relative motion members A and B is reduced, and the protrusion of the packing 100 is prevented.

Therefore, it is desirable that the gap Z existing between the inner and outer peripheral surfaces 20 and 30 of the backup ring 200 and the relative motion members A and B is small from the beginning.
However, in consideration of mounting properties and dimensional tolerances, a certain gap is allowed at present.
Further, the material of the backup ring 200 is desirably as hard as possible from the viewpoint of increasing the pressure resistance.

However, when a hard material is used, the backup ring 200 cannot be sufficiently stretched, and the gap cannot be reduced.
On the other hand, when a soft material such as PTFE is used, the pressure resistance is insufficient and there is a problem that it cannot be used for high pressure applications.
Therefore, as shown in FIG. 6, a mode has been proposed in which two types of backup rings 201 and 202 having different hardnesses are used in combination.
However, since these types of backup rings 201 and 202 use a plurality of different types of backup rings, there is a problem that the cost is increased and the installation space is inevitably increased.

Further, there has been proposed a mode in which the taper surface 300 is provided on the backup ring 203 and the bottom surface of the groove 110 corresponding to the taper surface 300 is the same taper surface 3001 (Japanese Patent Laid-Open No. 11-315925).
However, since this type of groove has a special groove shape, it has a problem of increasing the cost for groove processing.
Japanese Patent Laid-Open No. 11-315925

  However, the conventional backup ring described above is expensive and it is difficult to completely eliminate the gap between the backup ring and the relative motion member.

The present invention has been made in view of such problems, and an object of the present invention is to provide a backup ring that can reliably prevent the seal member from protruding and maintain good sealing performance.
Another object of the present invention is to provide a backup ring that is relatively inexpensive and can prevent the seal member from protruding.

  It is another object of the present invention to provide a backup ring that can prevent the seal member from protruding even when a high fluid pressure acts.

  The backup ring of the present invention is used together with a seal member that seals between the relative motion members, and the backup ring prevents the seal member from protruding into the gap between the relative motion members due to the pressure of the sealed fluid. The ring includes a curved surface portion that is recessed toward the seal member.

  The inner and outer peripheral surfaces of the backup ring of the present invention are parallel to the axis.

The backup ring of the present invention is characterized in that both inner and outer peripheral surfaces of the backup ring on the seal member side are in close contact with the relative motion member when pressed by the seal member and deformed into a flat plate shape.
In addition, the backup ring of the present invention is characterized in that straight portions are provided on both sides of the curved surface portion.

  According to the backup ring of the present invention, a gap exists between the inner and outer peripheral ends of the backup ring and the relative motion member when the backup ring is not pressed by the seal member.

The present invention has the following effects.
According to the backup ring of the first aspect of the present invention, it is possible to save space, reduce the number of parts, withstand high pressure, and reduce the gap between the inner peripheral surface of the backup ring and the peripheral surface between the relative motion members.

Furthermore, according to the backup ring of the invention described in claim 2, it is possible to reliably eliminate the gap between the inner peripheral surface of the backup ring and the peripheral surface between the relative motion members.
According to the backup ring of the third aspect of the present invention, when a high pressure is applied, it is possible to reliably eliminate the gap between the inner peripheral surface of the backup ring and the peripheral surface between the relative motion members.
According to the backup ring of the invention described in claim 4, the pressure resistance can be further improved.
Moreover, according to the backup ring of the invention described in claim 5, the seal member is reliably prevented from protruding at the time of high pressure, and the mounting property is good.

Hereinafter, the best mode for carrying out the present invention will be described.
The best mode for carrying out the invention will be described with reference to FIGS. 1 to 3. FIG.
In FIG. 1, an annular groove 10 is formed on the inner peripheral surface of the housing which is one of the relative motion members A.

In the groove 1, a backup ring 0 made of a resin material and a seal member 1 are arranged in the axial direction.
The backup ring 0 is harder than the seal member 1, and metal, resin, hard rubber or the like can be used, but resin is preferable. As the resin material, polyamide resin, polyacetal resin, tetrafluoroethylene resin, or the like is used, and polyamide resin is particularly preferable from the viewpoint of pressure resistance.
As the seal member 1, a pressure-resistant seal such as a packing made of a rubber-like elastic material or an O-ring is used together with the backup ring 0.

The backup ring 0 includes a curved surface portion X that is recessed toward the seal member 1.
The backup ring 0 has a substantially C-shaped cross section and a uniform thickness.
Further, the outer peripheral surface 2 of the backup ring 0 is parallel to the bottom surface 11 of the groove 10 and has a gap Z in an unloaded state.

Further, the inner peripheral surface 3 of the backup ring 0 is parallel to the shaft outer peripheral surface 12 which is the other relative motion member B, and has a gap Z in an unloaded state.
For this reason, the outer peripheral end 4 and the inner peripheral end 5 which are axial ends of the inner and outer periphery of the backup ring 0 on the seal member 1 side are acute corners.
When pressure is applied to such a backup ring 0 through the seal member 1 from the right side of the figure, the backup ring 0 is deformed into a flat plate shape as shown in FIG.

  As a result, the backup ring 0 expands in the radial direction, and the outer peripheral end 4 and the inner peripheral end 5 come into contact with the bottom surface 11 of the groove 10 and the shaft outer peripheral surface 12, respectively, and the gap Z is eliminated.

FIG. 3 shows another embodiment.
The difference from FIG. 1 is that straight portions Y and Y are provided on both sides of the curved surface portion X.
Thus, it is preferably used when pressure resistance is required.

  From the above, according to the best mode for carrying out the present invention, the gap between the inner peripheral surface of the backup ring and the peripheral surface of the relative motion member is reliably eliminated without changing the structure of the conventional seal member. Can make things possible

  The present invention is not limited to the best mode for carrying out the invention described above, and various other configurations can be adopted without departing from the gist of the present invention.

It is sectional drawing using the backup ring concerning this invention. It is sectional drawing which shows the usage example in the state where the pressure acted on the backup ring of FIG. It is sectional drawing which shows the other Example of the backup ring concerning this invention. It is sectional drawing which shows the usage example which used the backup ring of the prior art example with the sealing member. FIG. 5 is a cross-sectional view showing a state in which pressure is applied to the conventional backup ring of FIG. It is sectional drawing which shows the usage example which used the backup ring of the prior art example with the sealing member. It is sectional drawing which shows the usage example which used the backup ring of the prior art example with the sealing member.

Explanation of symbols

0 ... Backup ring 1 ... Sealing member 2 ... Outer peripheral surface 3 ... Inner peripheral surface 4 ... Outer peripheral end 5 ... Inner peripheral end 10 ... Groove 11 ... Bottom 12 ... Shaft outer peripheral surface

Claims (5)

  It is used together with a seal member (1) for sealing between the relative motion members (A) and (B), and the seal member (1) is placed in the gap between the relative motion members (A) and (B) by the pressure of the sealed fluid. In the backup ring (0) for preventing protrusion, the backup ring (0) includes a curved surface portion (X) that is recessed toward the seal member (1).   The backup ring according to claim 1, wherein the inner and outer peripheral surfaces (2) and (3) of the backup ring (0) are parallel to the axis.   When the backup ring (0) is pressed by the seal member (1) and deformed into a flat plate shape, both inner and outer peripheral ends (4) (5) of the backup ring (0) on the seal member (1) side. The back-up ring according to claim 1 or 2, wherein the ring is in close contact with the relative motion member (A) (B).   The backup ring according to any one of claims 1 to 3, further comprising linear portions (Y) (Y) on both sides of the curved surface portion (X) of the backup ring (0).   In a state where the backup ring (0) is not pressed by the seal member (1), between the inner and outer peripheral ends (4) and (5) of the backup ring (0) and the relative motion members (A) and (B). The backup ring according to any one of claims 1 to 4, wherein a gap (Z) exists in the ring.

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