JP5093743B2 - Backup ring - Google Patents

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, general machine cylinders, 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.

Furthermore, as shown in FIG. 7 , a mode has been proposed in which a 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 301 (JP-A-11-315925). issue).
However, since this type of groove has a special groove shape, it has a problem of increasing the cost for groove processing.

Accordingly, a backup ring 204 having the shape shown in FIGS. 8 and 9 has been proposed (Japanese Patent Laid-Open No. 8-135595).
The cross-sectional shape of this kind of backup ring 204 is a parallelogram, and when it is pressed by the packing 100 and deformed as shown in FIG. 9, it is provided on the outer peripheral surface 400 of the backup ring 204 and one relative motion member A. A gap 410 is formed between the bottom surface 113 of the annular groove 110.

Since this gap 410 is open to the packing 100 side, there is a problem that a part of the packing 100 bites into this gap 410.
Then, when the backup ring 204 returns from the state shown in FIG. 9 to the state shown in FIG. 8, there is a problem that a part of the packing 100 that bites into the gap 410 is damaged.
JP 11-315925 A JP-A-8-135595

  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.
Furthermore, even when the backup ring is deformed by a high pressure, there is no gap on the seal member side, so that there is no risk that a part of the seal member is damaged by the backup ring.

The backup ring of the present invention is used 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. In a state where the ring is not pressed , the first radial direction has a substantially quadrangular cross section and is in contact with the seal member and an obtuse angle with the outer peripheral surface of the relative motion member on the side in contact with the seal member An inclined surface, a second radial inclined surface substantially parallel to the first radial inclined surface, and the first radial inclined surface and the second radial inclined surface are connected on the inner peripheral side. An inner peripheral surface, an outer peripheral surface connecting the first radial inclined surface and the second radial inclined surface on the outer peripheral side, the outer peripheral surface and the first radial inclined surface; The angle formed by is 90 degrees, etc. Squid smaller than 90 degrees, and an angle formed between the inner peripheral surface and the first radial inclined surface, characterized in that an acute angle.

In addition, the backup ring of the present invention is characterized in that an angle formed between the outer peripheral surface and the first radially inclined surface is an acute angle.
The backup ring of the present invention is characterized in that the angle formed by the inner peripheral surface and the first radially inclined surface is an acute angle. The backup ring of the present invention is characterized in that the material is polyamide. .
The inner and outer peripheral surfaces of the backup ring of the present invention are parallel to the axis.

  Further, the backup ring of the present invention is characterized in that the seal member is a rubber elastic material packing.

The backup ring according to the present invention is characterized in that a gap exists between the inner and outer peripheral ends of the backup ring and the relative motion member in a state where the backup ring is not pressed by the seal member.
Further, the backup ring of the present invention is configured such that when the backup ring is pressed by the seal member and the first radially inclined surface and the second radially inclined surface are deformed so as to be orthogonal to the axis, Both the inner and outer peripheral ends where the radially inclined surfaces and the inner and outer peripheral surfaces intersect are in close contact with the peripheral surface of the relative motion member.

  Further, according to the backup ring of the present invention, the backup ring is used for a hydraulic cylinder together with a rubber elastic material packing.

  According to the backup ring of the present invention, it is possible to reliably eliminate the gap between the inner peripheral surface of the backup ring and the relative motion member without changing the conventional seal structure.

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 reliably eliminate the gap between the inner peripheral surface of the backup ring and the peripheral surface between the relative motion members. Therefore, the seal member is not damaged by the backup ring.

According to the backup ring of the second aspect of the present invention, there is no gap that opens on the seal member side between the outer peripheral surface of the backup ring and the peripheral surface of one of the relative motion members.
Furthermore, according to the backup ring of the third aspect of the present invention, there is no gap that opens on the seal member side between the inner peripheral surface of the backup ring and the peripheral surface of the other relative motion member.

Furthermore, according to the backup ring of the invention as set forth in claim 4, the molding is easy and the relative motion member is not damaged.
Further, according to the backup ring of the invention described in claim 5, it can withstand high pressure.
Further, according to the backup ring of the sixth aspect of the present invention, it is possible to reliably prevent damage to the rubber elastic material packing.

In addition, according to the backup ring of the seventh aspect of the invention, it is possible to improve the wearability.
According to the backup ring of the invention described in claim 8, it is possible to reliably prevent the seal member from protruding when the pressure is high.

  In addition, the backup ring according to the ninth aspect of the invention is suitable for use in a place where a high pressure acts, such as a hydraulic cylinder.

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, ethylene tetrafluoride 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 rubber-like elastic material or an O-ring is used together with the backup ring 0.

  The backup ring 0 has a substantially quadrangular cross section, a first radially inclined surface 7, a second radially inclined surface 2 substantially parallel to the first radially inclined surface 7, and a first radially inclined surface. An inner peripheral surface 3 connecting the surface 7 and the second radially inclined surface 2 on the inner peripheral side, and a first radial inclined surface 7 and the second radial inclined surface 2 connected on the outer peripheral side. The outer peripheral surface 4 is provided.

The angle X formed by the outer peripheral surface 4 and the first radially inclined surface 7 is equal to or smaller than 90 degrees.
Usually, the angle X formed by the outer peripheral surface 4 and the first radially inclined surface 7 is an acute angle.
The angle Y formed by the inner peripheral surface 3 and the first radially inclined surface 7 is also an acute angle.
The backup ring 0 in FIG. 1 shows a state in which the backup ring 0 in FIG. 2 is pressed by the seal member 1.

  In this backup ring 0, the angle X formed by the outer peripheral surface 4 and the first radially inclined surface 7 is formed at approximately 90 degrees, so that the first radially inclined surface 7 is formed as shown in FIG. When deformed so as to be substantially perpendicular to the axis, the entire outer peripheral surface 4 comes into close contact with the bottom surface 11 of the annular groove 10 provided in one relative motion member A.

In the state where the backup ring 0 is not pressed by the seal member 1, a gap exists between the inner and outer peripheral ends 5 and 6 of the backup ring 0 and the relative motion members A and B.
Thus, when the backup ring 0 is pressed by the seal member 1 and the first radially inclined surface 7 and the second radially inclined surface 2 are deformed so as to be orthogonal to the axis, the first of the backup ring 0 is Both the inner and outer peripheral end portions 5 and 6 where the radially inclined surface 7 and the inner and outer peripheral surfaces 3 and 4 intersect each other are in close contact with the peripheral surfaces of the relative motion members A and B, and there is no gap opened on the seal member 1 side. .

FIG. 3 shows another embodiment.
The difference from FIG. 2 is that the angle X formed by the outer peripheral surface 4 and the first radially inclined surface 7 is an acute angle.
As a result, the outer peripheral end portion 5 is in sharp contact with the bottom surface of the groove 10, so that the seal member can be more reliably prevented from protruding.

  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

  Further, 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 which showed the high voltage | pressure state using the backup ring concerning this invention. FIG. 2 is a cross-sectional view showing a state where no pressure is applied to the backup ring of FIG. 1. 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. 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 state which the pressure acted on the backup ring of the prior art example of FIG.

Explanation of symbols

0 ... Backup ring 1 ... Seal member 2 ... Second radially inclined surface 3 ... Inner peripheral surface 4 ... Outer peripheral surface 5 ... Outer peripheral end 6 ... Inner peripheral end 7 ... First Radially inclined surface 10 ... groove 11 ... bottom surface

Claims (8)

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) has a substantially square cross section when not pressed , and is in contact with the seal member (1) and the seal member (1). A first radially inclined surface (7) having an obtuse angle with the outer peripheral surface of the relative motion member (B) on the contact side, and a second substantially parallel to the first radially inclined surface (7) A radially inclined surface (2), an inner peripheral surface (3) connecting the first radially inclined surface (7) and the second radially inclined surface (2) on the inner peripheral side; Connecting the first radially inclined surface (7) and the second radially inclined surface (2) on the outer peripheral side An angle (X) formed by the outer peripheral surface (4) and the first radially inclined surface (7) is equal to or smaller than 90 degrees, and The backup ring according to claim 1, wherein an angle (Y) formed between the inner peripheral surface (3) and the first radially inclined surface (7) is an acute angle.   The backup ring according to claim 1, wherein an angle (X) formed by the outer peripheral surface (4) and the first radially inclined surface (7) is an acute angle.   The backup ring according to claim 1, wherein the material of the backup ring is a resin material.   The backup ring according to claim 3, wherein the material of the backup ring is a polyamide material.   The backup ring according to any one of claims 1 to 4, wherein the seal member (1) is a rubber-like elastic packing.   In a state where the backup ring (0) is not pressed by the seal member (1), between the inner and outer peripheral ends (5) and (6) of the backup ring (0) and the relative motion members (A) and (B) The back-up ring according to claim 1, wherein a gap exists in the back-up ring.   The backup ring (0) is pressed by the seal member (1), and the first radially inclined surface (7) and the second radially inclined surface (2) are deformed so as to be perpendicular to the axis. At the same time, both inner and outer peripheral ends (5) and (6) where the first radially inclined surface (7) and the inner and outer peripheral surfaces (3) and (4) of the backup ring (0) intersect are the relative motion members ( The backup ring according to any one of claims 1 to 6, wherein the backup ring is in close contact with the peripheral surface of (A) and (B).   The said backup ring (0) is used for a hydraulic cylinder with rubber-like elastic material packing, The backup ring as described in any one of Claims 1-7 characterized by the above-mentioned.

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