JP2004100743A - Seal ring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-quality seal ring excellent in durability and productivity. <P>SOLUTION: The seal ring is for sealing the annular clearance between two members which are relatively moved each other. Oil grooves 10 extended circumferentially are provided to a region except a cut part 12 on a seal slide face 11. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a seal ring used for, for example, a hydraulic cylinder used in a construction machine or the like, for sealing an annular gap between two members.
[0002]
[Prior art]
FIG. 5 is a diagram showing a seal ring according to the related art.
[0003]
The seal ring 104 shown in FIG. 5 is made of resin and forms a sealing device 100 together with a rubber-like elastic back ring 105 for applying a sealing pressure, and is provided on the outer periphery of the piston 101 in the hydraulic cylinder. It is mounted in the mounting groove 102 to seal a gap between the piston 101 and the cylinder 103.
[0004]
The seal ring 104 has a sealing sliding surface 106 slidably and sealingly contacting the inner peripheral surface of the cylinder, and the buckling 105 applies sealing pressure to the sealing sliding surface 106 of the sealing ring 104.
[0005]
As a material for the seal ring, PTFE (polytetrafluoroethylene) has been conventionally used, but a polyamide resin having higher productivity and a high elastic modulus may be used in some cases.
[0006]
In this case, it is difficult to attach the seal ring because of its high elastic modulus and low elongation. To solve this problem, a cut portion is provided on at least a part of the circumference of the seal ring.
[0007]
However, a gap occurs in the cut portion due to the influence of the cylinder diameter tolerance, the seal ring outer diameter tolerance, and the like (in FIG. 5, when φA> φD, a gap is generated).
[0008]
Further, as shown in FIG. 6A, even when the initial cut gap is 0, when the hydraulic cylinder operates, the thermal expansion difference generated between the seal ring and the housing due to a rise in ambient temperature causes A difference occurs in the diameter dimension, and a compressive force F is generated in the circumferential direction of the cut portion of the seal ring (FIG. 6B).
[0009]
As a result, the cut portion is plastically deformed and permanent set (creep) is generated. Therefore, even if the ambient temperature is lowered and the compressed portion is released from the compressive force, the portion does not return to the original length, and the entire circumference is not changed. Is shortened, and a gap also occurs (FIG. 6C).
[0010]
In order to prevent the sealing performance from being impaired even if such a gap is formed, a so-called step cut type cut having a step as shown in FIG. 5B may be used in some cases. Thereby, the cut surface 172 in the circumferential direction becomes a sealing surface, and the sealing performance can be maintained.
[0011]
[Problems to be solved by the invention]
However, in such a conventional technology, the sliding resistance is large and the oil film is not completely formed on the sealing sliding surface due to the polyamide-based resin, and the lubricating state is discontinuous. There has been a problem that slip occurs.
[0012]
As a solution to this problem, there is a method of providing an oil groove on the sliding surface of the seal ring for improving the lubrication characteristics.
[0013]
In this case, in general, it is difficult to release the mold by molding, and therefore, it is best to provide the oil groove by post-processing using a lathe.
[0014]
However, since machining with a lathe results in a circumferentially continuous groove, if a conventional oil groove is formed in a seal ring exhibiting a step cut, the cut portion will be as shown in FIG.
[0015]
That is, when the gaps P and Q exist as shown in FIG. 7, they are conducted through the oil groove 110 and a flow path is formed. As a result, the circumferential cut surface 172 does not function as a seal surface. However, the leakage of the sealed fluid, which is a fatal defect, occurs.
[0016]
For this reason, the problem that the oil groove cannot be provided in the seal ring exhibiting the step cut, which is unavoidable, the sliding resistance is large, and the stick-slip occurs has been accepted.
[0017]
Therefore, as shown in FIG. 8, the present applicant has proposed an oil groove provided at a position that does not straddle the circumferential cut surface 172.
[0018]
The oil grooves 110 are provided on both sides of the circumferential cut surface 172, do not straddle the circumferential cut surface 172, and seal the circumferential cut surface 172 between the axial cut surfaces 171. It will be excellent.
[0019]
For example, even if gaps P and Q are formed in the cut portion as shown in FIG. 7A, the sealed state is ensured by the circumferential cut surface 172 acting as a seal surface, and the flow through the oil groove 110 is ensured. No road is formed.
[0020]
However, in this case, since the oil groove 110 is formed in the (step) cut portion 107, the strength of the cut portion 107 may be reduced.
[0021]
Further, cutting of the seal ring requires high processing accuracy.
[0022]
This is because the axial width of the seal ring is small in the axial cut, and if the seal ring is cut beyond the circumferential cut surface, the cut portion may be damaged. This is because a small space between the oil grooves must be cut.
[0023]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the related art, and an object of the present invention is to provide a high-quality seal ring having excellent durability and productivity.
[0024]
[Means for Solving the Problems]
In order to achieve the above object, in the present invention,
A seal ring for sealing an annular gap between two members relatively moving with each other,
A sealing sliding surface slidably sealingly contacting one of the two members,
A cutting having an axial cutting surface partially cut in the axial direction at at least two places at different circumferential positions of the ring body, and a circumferential cutting surface cut perpendicular to the axis so as to connect the axial cutting surfaces. Department and
In a seal ring with
A groove extending in the circumferential direction is provided in a region other than the cut portion of the sealing sliding surface.
[0025]
The provision of a groove extending in the circumferential direction in a region other than the cut portion of the sealing sliding surface means that the cut portion is not provided with a groove, whereby the circumferential cut surface is in the axial direction. The gap between the cut surfaces can be reliably sealed, and the sealing property is extremely excellent. Further, the strength of the cut portion does not decrease and the durability is excellent.
[0026]
And, in the region other than the cut portion, the groove is provided in the circumferential direction, so that the sliding resistance can be suppressed and the stick-slip can be prevented.
[0027]
The method of forming the groove is not particularly limited, but by forming the groove by molding, it is possible to easily perform processing without forming a groove in the cut portion. Here, the present inventor has confirmed that the mold can be released without any problem if the depth of the groove is about 0.2 mm.
[0028]
Also in the formation of the cut portion, a portion without a groove can be processed, so that the cut portion can be easily formed.
[0029]
That is, productivity can be improved.
[0030]
Here, the two members refer to, for example, a hydraulic cylinder and a piston that is reciprocally assembled to the cylinder. In the seal ring, the outer peripheral surface is a sealing sliding surface in the case of a piston seal, and the inner peripheral surface is a sealing sliding surface in the case of a rod seal.
[0031]
When the seal ring is provided in the annular gap between the two members, the sealing sliding surface is provided with a sealing pressure on one member by mounting a rubber-like elastic ring on the back side of the sealing sliding surface. It is also preferred that
[0032]
The seal ring is also preferably made of a polyamide resin material.
[0033]
Thereby, the productivity can be improved without any problem in the mountability of the seal ring.
[0034]
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to them unless otherwise specified. Absent.
[0035]
FIG. 1A is a schematic perspective view showing a seal ring 1 according to the present embodiment, FIG. 1B is an enlarged view of a cut portion provided in the seal ring 1, and FIG. FIG. 3 is a schematic cross-sectional view showing the mounted state of the seal ring 1 according to the present embodiment, and FIG. 3A is a schematic cross-sectional view showing the mounted state of the cut part in the mounted state of the seal ring 1. FIG. 3B is a diagram corresponding to a Y-Y cross section in FIG. 2.
[0036]
The seal ring 1 according to the present embodiment is made of resin, and seals an annular gap between two members as a sealing device. In the present embodiment, it is configured in combination with a back ring 2 which is a ring made of a rubber-like elastic body, and seals a gap between a cylinder 4 as one member and a piston 5 which is reciprocally assembled to the cylinder 4. Will be described.
[0037]
That is, as shown in FIG. 3, the sealing device 3 including the seal ring 1 and the back ring 2 is mounted in the mounting groove 6 formed on the outer periphery of the piston 5 and The cylinder 4 and the piston 5 are sealed by sliding contact with each other in a sealed state.
[0038]
The outer periphery of the seal ring 1 is slidably in close contact with the inner periphery of the cylinder housing 4, and the buckling 2 is located on the back side of the seal ring 1 and is combined with the mounting groove 6 on the outer periphery of the piston 5 in this state. Has been installed.
[0039]
Here, the mounting groove 6 formed on the outer periphery of the piston 5 has, for example, a rectangular cross section and is provided with an opening on the cylinder 4 side.
[0040]
The buckling 2 is an annular member having a substantially circular cross section and a width smaller than the width of the mounting groove 6, and is attached to the bottom surface of the mounting groove 6. However, the form of the buckling can be appropriately changed within a range in which the sealing pressure is applied to the seal ring.
[0041]
The inner circumference of the seal ring 1 is in contact with the outer circumference of the buckling 2 and is slightly smaller than the mounting groove 6. In the seal ring 1, the inner peripheral surface and the outer peripheral surface are cylindrical surfaces that are straight in the axial direction, and the outer peripheral surface is a sealing sliding surface 11 that slidably contacts the inner periphery of the cylinder 4. I have.
[0042]
As shown in FIG. 1, the seal ring 1 has a cut portion 12 in which one portion in the circumferential direction is divided. When the seal ring 1 is mounted, the cut portion 12 is expanded to have a large diameter. It is designed to be easily attached to various parts.
[0043]
The cutting portion 12 is partially cut in the seal ring 1 in the axial direction at two different positions in the circumferential direction. One is cut from the sealed fluid side, the other is cut from the sealed fluid side, and the center of the resin ring is cut in the axial direction. Up to this point, it has a cut surface 13 in the axial direction and a circumferential cut surface 14 connecting the cut surfaces in the axial direction. As a whole, a so-called step cut is formed by combining two stepped ends. I have.
[0044]
Here, the seal ring 1 is preferably made of a polyamide resin. Productivity is improved by using a polyamide resin.
[0045]
As a feature of the present embodiment, an oil groove 10 is provided on the sealed sliding surface 11 in a region other than the cut portion 12 so as to extend in the circumferential direction.
[0046]
The oil groove 10 may be cut and provided by post-processing, but may be formed by molding. By forming a groove by molding, it is possible to easily perform processing without forming a groove in the cut portion 12. Here, the depth of the oil groove is preferably about 0.2 mm.
[0047]
In this embodiment, as shown in FIGS. 1 and 2, the oil groove 10 is provided in the circumferential direction without intersecting two grooves each having a substantially rectangular cross section. However, the present invention is not limited to this. May be set as appropriate, for example, a single groove may be used as shown in FIG.
[0048]
As described above, in the present embodiment, since the oil groove 10 is not provided in the cutting portion 12, the circumferential cutting surface 14 can reliably seal between the axial cutting surfaces 13 and the sealing property is very excellent. Furthermore, the durability of the cut portion 12 is excellent without a decrease in strength.
[0049]
As shown in FIG. 2, even if the gaps P and Q are formed in the cut portion 12, since the oil groove 10 is not provided in the cut portion 12, the circumferential cut surface 14 reliably acts as a seal surface. As a result, a sealed state is ensured, and a flow path is not formed via an oil groove as in the related art.
[0050]
Then, by filling the oil groove 10 provided in the area other than the cutting portion 12 with lubricating oil, the sliding resistance between the sealing sliding surface 11 and the inner periphery of the cylinder 4 is suppressed. Stick-slip, which tends to occur in the case, can be prevented.
[0051]
Conventionally, a high degree of machining accuracy was required to cut between two oil grooves, but in the present embodiment, machining is easily performed because there is no oil groove in the cut portion. be able to.
[0052]
In the circumferential direction of the seal ring 1, only the cut portion 12 has no groove in a portion other than the cut portion 12, but since the cut portion has a good lubrication state from the beginning, stick-slip may occur. There is no.
[0053]
The seal ring according to the present embodiment may be formed of PTFE, or may be formed of a crystalline resin such as PPS (polyphenylene sulfide) or PBT (polybutylene terephthalate). A similar effect can be obtained, and various materials can be used depending on the application depending on required heat resistance and the like.
[0054]
Further, in the present embodiment, the case of the piston seal (the case where the outer peripheral surface is a sealing sliding surface) is described. However, the present invention is not limited to this, and the case of a rod seal (the inner peripheral surface is a sealing sliding surface). In the case of the moving surface), that is, the mounting groove 4 may be provided on the cylinder 2 side and open to the piston 3 side, and the seal ring may be mounted on the inner circumference of the cylinder. Further, in the present embodiment, the case has been described where the seal ring is configured in combination with the back ring 2 which is a ring made of a rubber-like elastic body. However, the present invention is not limited to this, and the seal ring may be used alone.
[0055]
【The invention's effect】
As described above, according to the present invention, a high-quality seal ring having excellent productivity, durability, and the like can be obtained by forming a groove at an appropriate position on a ring body having one portion divided in the circumferential direction. Can be provided.
[Brief description of the drawings]
FIG. 1A is a schematic perspective view showing a seal ring according to an embodiment of the present invention, and FIG. 1B is a schematic perspective view showing a cut portion thereof.
FIG. 2 is a schematic plan view of a cut portion in a state where the seal ring according to the present embodiment is mounted.
FIG. 3 is a schematic cross-sectional view showing a mounted state of the seal ring 1 according to the present embodiment, and FIG. 3 (a) corresponds to a cross section XX of FIG. 2, and FIG. 3 (b) FIG. 3 is a diagram corresponding to a YY cross section in FIG. 2.
FIG. 4 is a schematic perspective view showing a cut portion of a seal ring having one oil groove.
FIG. 5 (a) is a schematic diagram for explaining a conventional seal ring, and FIG. 5 (b) is an enlarged view of a cut portion thereof.
6A and 6B are schematic diagrams for explaining a conventional seal ring. FIG. 6A shows a state of the seal ring before use, FIG. 6B shows a state of the seal ring during use (at a high temperature), and FIG. c) shows the state of the seal ring after use (normal temperature).
7 (a) is an enlarged perspective view of a cut portion of a conventional seal ring with an oil groove, and FIG. 7 (b) is a sectional view taken along the line Z-Z of FIG. 7 (a).
FIG. 8A is a schematic perspective view for explaining a conventional seal ring with an oil groove, and FIG. 8B is an enlarged view of a cut portion thereof.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Seal ring 2 Buckling 3 Sealing device 4 Cylinder 5 Piston 6 Mounting groove 10 Oil groove 11 Sealing sliding surface 12 Cutting part 13 Cutting surface in axial direction 14 Cutting surface in circumferential direction

Claims (3)

A seal ring for sealing an annular gap between two members relatively moving with each other,
A sealing sliding surface slidably sealingly contacting one of the two members,
A cutting having an axial cutting surface partially cut in the axial direction at at least two places at different circumferential positions of the ring body, and a circumferential cutting surface cut perpendicular to the axis so as to connect the axial cutting surfaces. Department and
In a seal ring with
A seal ring, wherein a groove extending in a circumferential direction is provided in a region other than the cut portion of the sealing sliding surface. 2. The sealing sliding surface is provided with a sealing pressure on the one member by attaching a rubber-made elastic ring to the back side of the sealing sliding surface. Seal ring. The seal ring according to claim 1, further comprising a polyamide resin material.

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