JP7048536B2 - Seal ring - Google Patents

Description

The present invention relates to a seal ring that can be used in hydraulic equipment.

Automobiles equipped with various hydraulic devices such as hydraulic continuously variable transmissions are known. Seal rings for sealing oil are used in these hydraulic devices. The seal ring is fitted, for example, into a shaft inserted into the housing to seal between the shaft and the housing.

It is preferable that the seal ring can be closely attached to the shaft and the housing in order to realize a high sealing property between the shaft and the housing. Therefore, the seal ring is formed of an elastic body such as a resin. Patent Documents 1 and 2 disclose a seal ring made of a resin.

The seal ring slides back and forth with respect to the inner peripheral surface of the housing when the hydraulic equipment is driven. Therefore, the hydraulic equipment has a friction loss, which is a drive loss due to the friction between the seal ring and the housing. Therefore, in order to reduce the drive loss of hydraulic equipment, high slidability between the seal ring and the housing is required.

However, in a general seal ring, the sealability and the slidability tend to be in a trade-off relationship. On the other hand, Patent Document 3 describes a seal ring capable of achieving both sealing property and slidability. The seal ring is provided with an inclined surface that becomes thinner toward the sliding surface.

In the seal ring described in Patent Document 3, it is easy to compress and deform in the radial direction in a thin portion provided with an inclined surface. Therefore, in this seal ring, the contact pressure with respect to the sliding surface can be kept small even if it is sufficiently compressed and deformed in the radial direction. As a result, in this seal ring, high slidability can be obtained without impairing the sealing property.

Japanese Unexamined Patent Publication No. 2012-255495 Japanese Unexamined Patent Publication No. 2013-194884 International Publication No. 2017-146037

The inventor of the present application has found that in the seal ring described in Patent Document 3, stress concentration is likely to occur in the vicinity of a portion provided with an inclined surface that is greatly compressed and deformed in the radial direction. On the other hand, the inventor of the present application considered that it is effective to suppress stress concentration in the seal ring in order to further improve the performance such as reduction of fatigue wear.

In view of the above circumstances, an object of the present invention is to provide a sealing ring in which stress concentration is unlikely to occur.

In order to achieve the above object, the seal ring according to one embodiment of the present invention is formed of an elastic body having a tensile elastic modulus of 90 MPa or more at 25 ° C., and has a flat portion, a first deformed portion, and a second deformed portion. Equipped with.
The flat portion has a pair of side surfaces extending along the radial direction.
The first deformed portion is a pair of first inclined surfaces extending from the outer end portions of the pair of side surfaces in the radial direction toward the outside so as to be close to each other, and the pair of first inclined surfaces. It has an outer peripheral surface that connects the outer ends to each other and projects outward.
The second deformed portion includes a pair of second inclined surfaces extending inwardly toward the inside from the inner end portion of the pair of side surfaces in the radial direction, and the pair of second inclined surfaces. It has an inner peripheral surface that connects the inner ends to each other and projects inward.

The seal ring is provided with a first deformed portion on the outer peripheral side and a second deformed portion on the inner peripheral side. The first and second deformed portions are provided with first and second inclined surfaces so that compression deformation in the radial direction is likely to occur. Therefore, this seal ring is easily compressed and deformed in the radial direction on both the outer peripheral side and the inner peripheral side.
Therefore, in this seal ring, when the outer peripheral surface is a sliding surface, the stress applied to the first deformed portion constituting the outer peripheral surface is relaxed by the second deformed portion. Similarly, when the inner peripheral surface is a sliding surface, the stress applied to the second deformed portion constituting the inner peripheral surface is relaxed by the first deformed portion. Therefore, stress concentration is unlikely to occur in this seal ring.
Further, in this seal ring, the radial dimensions d12 and d13 of the first and second deformed portions are sufficiently increased. As a result, the flat portion having a wall thickness is more reliably fitted in the groove portion, and only the thin first or second deformed portion is arranged outside the groove portion. Therefore, this seal ring is less likely to be pinched in the gap between the housing and the shaft.

In the seal ring, the total radial dimension of the flat portion, the first deformed portion, and the second deformed portion is set to D, the radial dimension of the flat portion is set to d11, and the first deformed portion is set. Let d12 be the radial dimension of the above, and d13 be the radial dimension of the second deformation portion.
0.2 × D ≦ d11 ≦ 0.56 × D
0.22 × D ≦ d12 ≦ 0.4 × D
0.22 × D ≦ d13 ≦ 0.4 × D
It is preferable to satisfy the relationship.
With this seal ring, the flat portion can be deeply submerged in the groove portion of the shaft while ensuring the mechanical strength.

The first angle formed by the pair of first inclined surfaces and the pair of side surfaces is 30 ° or more and 40 ° or less, and the second angle formed by the pair of second inclined surfaces and the pair of side surfaces is 30 ° or more. It may be 40 ° or less.
The first radius of curvature of the outer peripheral surface may be 0.64 mm or more and 1.37 mm or less, and the second radius of curvature of the inner peripheral surface may be 0.64 mm or more and 1.37 mm or less.
The shore A hardness of the elastic body at 25 ° C. may be 80 or more.
With these configurations, the above effects are particularly well obtained.

As described above, the present invention can provide a sealing ring in which stress concentration is unlikely to occur.

It is a top view of the seal ring which concerns on one Embodiment of this invention. It is sectional drawing along the AA'line of FIG. 1 of the seal ring shown in FIG. It is sectional drawing which shows the state which the seal ring shown in FIG. 2 is fitted in a shaft. It is sectional drawing which shows the state which the shaft shown in FIG. 3 is inserted into a housing. FIG. 3 is a cross-sectional view showing a state in which the shaft and the housing shown in FIG. 4 are relatively reciprocating. It is sectional drawing which shows the state which the seal ring which concerns on Comparative Example 1 is fitted in the shaft. It is sectional drawing which shows the state which the shaft shown in FIG. 6 is inserted into a housing. It is sectional drawing which shows the state which the shaft and the housing shown in FIG. 7 reciprocate relatively. It is sectional drawing which shows the state which the seal ring which concerns on Comparative Example 2 is incorporated in a shaft and a housing. It is sectional drawing which shows the other structural example using the seal ring shown in FIG. It is a figure which shows the fatigue tester for evaluating the seal ring which concerns on Example and the comparative example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1. 1. Overall Configuration of Seal Ring 10 1.1 Schematic Configuration FIGS. 1 and 2 are views showing the seal ring 10 according to an embodiment of the present invention. FIG. 1 is a plan view of the seal ring 10. FIG. 2 is a cross-sectional view of the seal ring 10 along the AA'line of FIG. As shown in FIG. 1, the seal ring 10 is formed in an annular shape centered on the central axis E.

That is, FIG. 2 shows a radial cross section of the seal ring 10 along a plane passing through the central axis E shown in FIG. FIG. 2 shows a plane F extending along the radial direction orthogonal to the central axis E and passing through the center in the thickness direction along the central axis E of the seal ring 10. The seal ring 10 has a shape symmetrical with respect to the plane F.

The elastic body forming the seal ring 10 is formed of an elastic body having a relatively high rigidity and having one or more kinds of materials selected from a resin material and a rubber material as a main component. The elastic body forming the seal ring 10 may contain components other than the resin material such as various fillers and the rubber material, if necessary.

The seal ring 10 includes a flat portion 11 located in the central portion in the radial direction, a first deformed portion 12 located on the outer peripheral side of the flat portion 11, and a second deformed portion 13 located on the inner peripheral side of the flat portion 11. , Have. In the seal ring 10, the flat portion 11, the first deformed portion 12, and the second deformed portion 13 each have a uniform cross-sectional shape over the entire circumference thereof.

As shown in FIG. 2, in the seal ring 10, the flat portion 11 has a flat cross-sectional shape, and the first deformed portion 12 and the second deformed portion 13 have a cross-sectional shape that tapers as the distance from the flat portion 11 in the radial direction. Have. That is, the first deformed portion 12 and the second deformed portion 13 become thinner in the radial direction from the thickest flat portion 11.

The seal ring 10 has a pair of side surfaces 111 facing each other in the central axis E direction, and an outer peripheral surface 121 and an inner peripheral surface 131 facing each other in the radial direction. In the seal ring 10, the flat portion 11 constitutes the side surface 111, the first deformed portion 12 constitutes the outer peripheral surface 121, and the second deformed portion 13 constitutes the inner peripheral surface 131.

1.2 Configuration of Each Part The flat part 11 has a pair of side surfaces 111 that are parallel to the plane F and has a flat shape along the plane F. Since the flat portion 11 is thick in the central axis E direction, the flat portion 11 has higher radial rigidity than the first deformed portion 12 and the second deformed portion 13. Therefore, the seal ring 10 is less likely to be compressed and deformed in the radial direction at the flat portion 11.

The outer peripheral surface 121 provided on the first deformed portion 12 is a barrel-shaped curved surface protruding outward in the radial direction. As shown in FIG. 2, the outer peripheral surface 121 has an arcuate cross-sectional shape having a constant first radius of curvature Ra. In the seal ring 10, the outer peripheral surface 121 is configured as a sliding surface that slides with respect to the housing 30 (see FIG. 4 and the like).

The first deformed portion 12 is provided with a pair of first inclined surfaces 122 arranged between the outer peripheral surface 121 and each side surface 111. The first inclined surface 122 is inclined at a constant angle θa with respect to the side surface 111 so as to be close to each other from the inside to the outside in the radial direction. As shown in FIG. 2, the first inclined surface 122 has a linear cross-sectional shape.

Further, the first deformed portion 12 is provided with a connecting portion 123 for connecting the outer peripheral surface 121 and each of the first inclined surfaces 122. The connecting portion 123 can be formed, for example, into a curved surface that smoothly connects the outer peripheral surface 121 and each of the first inclined surfaces 122, or a linear shape that directly connects the outer peripheral surface 121 and each of the first inclined surfaces 122. ..

Further, the first deformed portion 12 is provided with a connecting portion 124 for connecting each side surface 111 and each first inclined surface 122. The connecting portion 124 can be formed, for example, into a curved surface that smoothly connects each side surface 111 and each first inclined surface 122, or a linear shape that directly connects each side surface 111 and each first inclined surface 122. ..

As described above, the dimension of the first deformed portion 12 in the central axis E direction decreases as the first deformed portion 12 is separated from the flat portion 11 in the radial direction. Therefore, the first deformed portion 12 has lower radial rigidity than the flat portion 11, and the portion outside the radial direction is more likely to be compressed and deformed in the radial direction. Therefore, the seal ring 10 is easily compressed and deformed in the radial direction in the first deformed portion 12.

The inner peripheral surface 131 provided on the second deformed portion 13 is a barrel-shaped curved surface protruding inward in the radial direction. As shown in FIG. 2, the outer peripheral surface 121 has an arcuate cross-sectional shape having a constant second radius of curvature Rb. In the seal ring 10, the outer peripheral surface 121 is configured as a contact surface in contact with the bottom surface (see FIG. 3 and the like) of the groove portion 21 of the shaft 20.

The second deformed portion 13 is provided with a pair of second inclined surfaces 132 arranged between the inner peripheral surface 131 and each side surface 111. The second inclined surface 132 is inclined at a constant angle θb with respect to the side surface 111 so as to be close to each other from the outside to the inside in the radial direction. As shown in FIG. 2, the second inclined surface 132 has a linear cross-sectional shape.

Further, the second deforming portion 13 is provided with a connecting portion 133 for connecting the inner peripheral surface 131 and each of the second inclined surfaces 132, respectively. The connecting portion 133 is formed, for example, into a curved surface that smoothly connects the inner peripheral surface 131 and each of the second inclined surfaces 132, or a linear shape that directly connects the inner peripheral surface 131 and each of the second inclined surfaces 132. Can be done.

Further, the second deformed portion 13 is provided with a connecting portion 134 for connecting each side surface 111 and each second inclined surface 132. The connecting portion 134 can be formed, for example, into a curved surface that smoothly connects each side surface 111 and each second inclined surface 132, or a linear shape that directly connects each side surface 111 and each second inclined surface 132. ..

As described above, the dimension of the second deformed portion 13 in the central axis E direction decreases as the second deformed portion 13 is moved inward in the radial direction from the flat portion 11. Therefore, the second deformed portion 13 has lower radial rigidity than the flat portion 11, and the inner portion in the radial direction is more likely to be compressed and deformed in the radial direction. Therefore, the seal ring 10 is easily compressed and deformed in the radial direction in the second deformed portion 13.

As described above, the seal ring 10 is less likely to be compressionally deformed in the radial direction in the flat portion 11 having high rigidity, and is likely to be compressionally deformed in the radial direction in the first deformed portion 12 and the second deformed portion 13 having low rigidity. That is, the seal ring 10 is configured so that the first deforming portion 12 and the second deforming portion 13 are selectively compressed and deformed in the radial direction.

2. 2. Details of the seal ring 10 2.1 Action and effect of the seal ring 10 FIG. 3 is a cross-sectional view showing a state in which the seal ring 10 is mounted on the shaft 20. FIG. 3 shows a grid line for expressing the state of elastic deformation of each configuration in the seal ring 10. That is, in the seal ring 10, when elastic deformation is applied from the state shown in FIG. 3, the spacing between the grid lines changes according to the mode of the deformation.

The shaft 20 is a columnar component used in hydraulic equipment, and has a groove portion 21 formed over the entire circumference of the outer peripheral surface thereof. Further, the shaft 20 is formed with a tapered portion 22 by chamfering along the outer edge portion of the groove portion 21. The seal ring 10 is fitted in the groove 21 of the shaft 20.

In the seal ring 10 shown in FIG. 3, the inner peripheral surface 131 of the second deformed portion 13 is in close contact with the bottom surface of the groove portion 21 of the shaft 20 over the entire circumference thereof. Further, in the seal ring 10 shown in FIG. 3, the first deformed portion 12 does not fit in the groove portion 21 and protrudes radially outward from the outer peripheral surface of the shaft 20.

FIG. 4 is a cross-sectional view showing a state in which the shaft 20 shown in FIG. 3 is inserted into the housing 30. The housing 30 is a cylindrical component through which the shaft 20 can be inserted. The diameter of the inner peripheral surface of the housing 30 is larger than the diameter of the outer peripheral surface of the shaft 20, and smaller than the diameter of the outer peripheral surface 121 of the seal ring 10 shown in FIG.

Therefore, when the shaft 20 is inserted into the housing 30, a pressing force is applied radially inward from the inner peripheral surface of the housing 30 to the outer peripheral surface 121 of the seal ring 10. In the seal ring 10, when the outer peripheral surface 121 receives a pressing force from the inner peripheral surface of the housing 30, the first deformed portion 12 is compressed and deformed in the radial direction.

At this time, the flat portion 11 having high rigidity sinks to the inner peripheral side while compressing and deforming the second deformed portion 13 in the radial direction due to the internal stress generated by the radial compressive deformation of the first deformed portion 12. As a result, in the seal ring 10, the internal stress is dispersed from the first deformed portion 12 to the second deformed portion, so that the internal stress of the first deformed portion 12 is relaxed.

In the seal ring 10 formed of an elastic body having a relatively high rigidity, the internal stress generated by the pressing force applied to the outer peripheral surface 121 is satisfactorily transmitted to the inner peripheral side, and the flat portion 11 smoothly sinks to the inner peripheral side. As a result, in the seal ring 10 shown in FIG. 4, the maximum value of the internal stress can be kept small without causing stress concentration.

Stress concentration in an elastic body causes a decrease in fatigue strength. Therefore, in the seal ring 10, fatigue wear can be kept low by suppressing stress concentration. Further, in the seal ring 10, stress concentration, which can be a starting point of brittle fracture, is unlikely to occur, so that high durability can be obtained.

Further, in the seal ring 10 shown in FIG. 4, the first deformed portion 12 and the second deformed portion 13 having low rigidity in the radial direction are mainly elastically deformed in the radial direction. Therefore, in the seal ring 10, the elastic force can be kept small even in a state where the first deformed portion 12 and the second deformed portion 13 are largely compressed and deformed in the radial direction.

Therefore, in the seal ring 10, the contact pressure of the outer peripheral surface 121 with respect to the housing 30 can be kept low even in a configuration in which the first deformed portion 12 and the second deformed portion 13 are sufficiently large and compressed and deformed in the radial direction. Therefore, the seal ring 10 can achieve both high sealing performance and high slidability.

FIG. 5 is a cross-sectional view showing a state in which the shaft 20 and the housing 30 shown in FIG. 4 are relatively reciprocating. FIG. 5 shows a state in which the housing 30 is moving toward the right side with respect to the shaft 20. In the seal ring 10 shown in FIG. 5, the outer peripheral surface 121 is dragged to the right by the inner peripheral surface of the housing 30, and the first deformed portion 12 is elastically deformed.

However, in the seal ring 10, the contact pressure of the outer peripheral surface 121 with respect to the inner peripheral surface of the housing 30 is small, that is, the frictional force applied between the outer peripheral surface 121 and the inner peripheral surface of the housing 30 is small, so that the seal ring 10 is applied to the outer peripheral surface 121. The force in the right direction is suppressed to a small extent. As a result, in the seal ring 10, the amount of elastic deformation of the first deformed portion 12 can be kept small.

Further, in the seal ring, the flat portion 11 having a wall thickness sinks to the inner peripheral side, so that the flat portion 11 is accommodated inside the tapered portion 22 in the groove portion 21 of the shaft 20. That is, in the seal ring 10, only the first deformed portion 12 that becomes thinner toward the outside is arranged in the region outside the tapered portion 22 of the shaft 20.

In the seal ring 10 shown in FIG. 4, the first inclined surface 122 of the first deformed portion 12 is moved outward from the tapered portion 22 in the radial direction. Therefore, as shown in FIG. 5, the seal ring 10 is provided in the space between the tapered portion 22 of the shaft 20 and the inner peripheral surface of the housing 30 even if the outer peripheral surface 121 is dragged by the inner peripheral surface of the housing 30. It is difficult to enter.

As a result, the seal ring 10 can prevent the seal ring 10 from entering the gap between the shaft 20 and the housing 30 beyond the tapered portion 22 when the hydraulic device is driven. Therefore, in the seal ring 10, it is possible to prevent the occurrence of defects such as breakage due to being sandwiched between the shaft 20 and the housing 30.

2.2 Specific configuration of the seal ring 10 As described above, the seal ring 10 is formed of an elastic body having a relatively high rigidity in order to transmit internal stress well in the radial direction. Specifically, the elastic modulus of the elastic body forming the seal ring 10 at 25 ° C. is 90 MPa or more, preferably 120 MPa or more. Further, the shore A hardness of the elastic body forming the seal ring 10 at 25 ° C. is preferably 80 or more.

The tensile elastic modulus of the elastic body forming the seal ring 10 can be obtained, for example, as stress (σ) / strain (ε) in a tensile test based on JIS K6251. At the time of the tensile test, the elastic body can be processed into a No. 3 type dumbbell test piece. Further, the tensile speed in the tensile test can be 500 mm / min.

The shore A hardness of the elastic body forming the seal ring 10 can be measured using a type A durometer, for example, based on JIS K7215. As a sample for measuring the shore A hardness, for example, a seal ring 10 formed of the elastic body cut out into an appropriate shape can be used.

Further, as described above, in the seal ring 10, it is necessary to increase the radial dimensions of the first deformed portion 12 and the second deformed portion 13 to some extent in order to allow the flat portion 11 to sink deeply into the groove portion 21 of the shaft 20. There is. Further, in the seal ring 10, it is not preferable that the radial dimension of the flat portion 11 is too small in order to secure the mechanical strength.

In FIG. 2, regarding the seal ring 10, the total radial dimension D (diametrical dimension D of the seal ring 10) of the flat portion 11, the first deformed portion 12, and the second deformed portion 13 and the flat portion 11 are shown. The radial dimension d11, the radial dimension d12 of the first deformed portion 12, and the radial dimension d13 of the second deformed portion 13 are shown.

From the above viewpoint, in the seal ring 10, it is preferable that the dimensions D, d11, d12, and d13 satisfy the following relationship.
0.2 × D ≦ d11 ≦ 0.56 × D
0.22 × D ≦ d12 ≦ 0.4 × D
0.22 × D ≦ d12 ≦ 0.4 × D

Further, in the seal ring 10, the first angle θa of the first inclined surface 122 and the second angle of the second inclined surface 132 are obtained so that the first deformed portion 12 and the second deformed portion 13 are appropriately compressed and deformed in the radial direction. θb is determined. Specifically, it is preferable that the first angle θa of the first inclined surface 122 and the second angle θb of the second inclined surface 132 are both 30 ° or more and 40 ° or less.

Further, in the seal ring 10, the first radius of curvature Ra of the outer peripheral surface 121 and the second radius of curvature Rb of the inner peripheral surface 131 so that the first deformed portion 12 and the second deformed portion 13 are appropriately compressed and deformed in the radial direction. Is determined. Specifically, it is preferable that the first radius of curvature Ra of the outer peripheral surface 121 and the second radius of curvature Rb of the inner peripheral surface 131 are both 0.64 mm or more and 1.37 mm or less.

In addition, the first radius of curvature Ra of the outer peripheral surface 121 and the second radius of curvature Rb of the inner peripheral surface 131 are equal, and the first angle θa of the first inclined surface 122 and the second angle θb of the second inclined surface 132 are equal. Equal is preferable. That is, in the seal ring 10, it is preferable that the first deformed portion 12 and the second deformed portion 13 have the same cross-sectional shape.

As a result, in the seal ring 10, the amount of compressive deformation in the radial direction of the first deformed portion 12 and the second deformed portion 13 becomes the same in the state of being incorporated in the shaft 20 and the housing 30 shown in FIG. 4, and the internal stress is reduced. Best dispersed. Therefore, in the seal ring 10 having this configuration, stress concentration is less likely to occur.

2.3 Comparative Example FIG. 6 is a cross-sectional view showing a state in which the seal ring 10a according to Comparative Example 1 is fitted into the groove portion 21 of the shaft 20. The seal ring 10a is composed of a deformed portion 12a on the outer peripheral side and a flat portion 11a. That is, the seal ring 10a does not have a configuration corresponding to the second deformed portion 13 on the inner peripheral side of the seal ring 10 according to the present embodiment.

FIG. 7 is a cross-sectional view showing a state in which the shaft 20 shown in FIG. 6 is inserted into the housing 30. In the seal ring 10a, the internal stress generated in the deformed portion 12a due to the pressing force applied from the inner peripheral surface of the housing 30 is not transmitted to the inner peripheral side. Therefore, in the seal ring 10a, the internal stress is not relaxed, so that stress concentration is likely to occur.

Specifically, in the seal ring 10a, stress concentration is likely to occur in the region R shown by the dot pattern in FIG. 7 near the boundary between the deformed portion 12a and the flat portion 11a. Therefore, the seal ring 10a is liable to cause problems such as fatigue wear due to stress concentration, and therefore, the durability as high as that of the seal ring 10 according to the present embodiment cannot be obtained.

Further, as shown in FIG. 7, in the seal ring 10a according to Comparative Example 1, the flat portion 11a having a wall thickness does not sink inward from the tapered portion 22 in the groove portion 21 of the shaft 20. Therefore, in the seal ring 10a, a part of the flat portion 11a projects onto the tapered portion 22 of the shaft 20 due to elastic deformation.

FIG. 8 is a cross-sectional view showing a state in which the shaft 20 and the housing 30 shown in FIG. 7 are relatively reciprocating. At this time, the inner peripheral surface of the housing 30 drags the deformed portion 12a of the seal ring 10a to the right with a part of the seal ring 10a sandwiched between the inner peripheral surface of the housing 30 and the tapered portion 22 of the shaft 20.

As a result, in the seal ring 10a, a strong force in the right direction is applied from the inner peripheral surface of the housing 30 to the deformed portion 12a, and the deformed portion 12a is placed in the space between the tapered portion 22 of the shaft 20 and the inner peripheral surface of the housing 30. Be drawn in. Therefore, the seal ring 10a easily enters the gap between the shaft 20 and the housing 30 beyond the tapered portion 22.

If the seal ring 10a is sandwiched between the shaft 20 and the housing 30, the reciprocating movement between the shaft 20 and the housing 30 may be hindered, and the hydraulic equipment may malfunction. Further, if the seal ring 10a sandwiched between the shaft 20 and the housing 30 is broken, there is a possibility that debris may be mixed into the hydraulic equipment.

FIG. 9 is a cross-sectional view showing a state in which the seal ring 10b according to Comparative Example 2 is incorporated in the shaft 20 and the housing 30. The seal ring 10b has the same shape as the seal ring 10 according to the present embodiment, but is formed of a low-rigidity elastic body having a tensile elastic modulus of less than 90 MPa at 25 ° C., which is different from the configuration of the present embodiment. different.

In an elastic body having low rigidity forming the seal ring 10b, it is difficult to transfer internal stress well. Therefore, in the seal ring 10b, even if an internal stress is generated in the first deformed portion 12b due to the pressing force applied from the inner peripheral surface of the housing 30, the flat portion 11 does not smoothly sink to the inner peripheral side, and the second deformed portion 11b is deformed. The amount of compression deformation in the radial direction of the portion 13b remains small.

Therefore, in the seal ring 10b, the internal stress generated in the first deformed portion 12b is not relaxed and tends to concentrate. Specifically, in the seal ring 10b, stress concentration is likely to occur in the region R shown by the dot pattern in FIG. 9 near the boundary between the first deformed portion 12b and the flat portion 11a. Therefore, it is difficult to obtain high durability with the seal ring 10b.

2.4 Other Configuration Examples In the seal ring 10 according to the present embodiment, the inner peripheral surface 131 may be used as the sliding surface instead of the outer peripheral surface 121. FIG. 10 is a cross-sectional view showing a state in which the seal ring 10 is incorporated into a shaft 20a having a flat outer peripheral surface and a housing 30a having a groove portion 31a formed on the inner peripheral surface.

In the state shown in FIG. 10, the shaft 20a is inserted into the housing 30a in which the seal ring 10 is fitted in the groove portion 31a. As a result, in the seal ring 10, the inner peripheral surface 131 is in contact with the outer peripheral surface of the shaft 20a, and the outer peripheral surface 121a is in contact with the bottom surface of the groove portion 31a of the housing 30a.

In the configuration shown in FIG. 10, the first deformed portion 12 and the second deformed portion 13 in the seal ring 10 perform functions opposite to those shown in FIG. As a result, even in the configuration shown in FIG. 10, the effect of the seal ring 10 can be obtained, in which stress concentration is less likely to occur and both high sealing performance and high slidability can be achieved, as in the configuration shown in FIG.

3. 3. Examples and Comparative Examples Seven types of samples S1 to S7 were prepared as examples and comparative examples of the seal ring 10 according to the present embodiment. Sample S1 has the configuration of the seal ring 10a according to Comparative Example 1. Samples S2 to S4 have the configuration of the seal ring 10b according to Comparative Example 2. Samples S5 to S7 have the configuration of the seal ring 10 according to the present embodiment.

That is, the sample S1 according to Comparative Example 1 is different from the configuration of the present embodiment in that the second deformation portion on the inner peripheral side is not provided. The samples S2 to S4 according to Comparative Example 2 are different from the configuration of the present embodiment in that they are formed of a low-rigidity elastic body having a tensile elastic modulus of less than 90 at 25 ° C. Samples S5 to S7 are examples of this embodiment.

In each of the samples S2 to S7 in which the deformed portion is provided on both the outer peripheral side and the inner peripheral side, the first angle θa of the first inclined surface and the second angle θb of the second inclined surface are equal, and the outer peripheral surface is The first radius of curvature Ra and the second radius of curvature Rb of the inner peripheral surface are equal. Table 2 shows the angles θa and θb and the radii of curvature Ra and Rb in the samples S1 to S7.

Fatigue tests were performed on samples S1 to S7. The fatigue tester 50 shown in FIG. 11 was used for the fatigue test of each sample. The fatigue tester 50 includes a shaft 51 in which a groove into which each sample is fitted is formed, and a housing 52 in which the shaft 51 can be inserted.

The tightening ratio (%), which is the ratio of the amount of compression deformation in the radial direction to the radial dimension D (see FIG. 2) in each sample, uses the distance L between the bottom surface of the groove portion of the shaft 51 and the inner peripheral surface of the housing 52. Therefore, it can be calculated as 100 × (DL) / D. In each sample fatigue test, the tightening rate was adjusted to about 11%.

Then, a fatigue test was conducted in which the shaft 51 in which the sample was fitted in the groove was reciprocated with respect to the housing 52. Specifically, as a condition for the reciprocating motion of the shaft 51 with respect to the housing 52 in the fatigue test of each sample, the cycle number was 4.2 million times with a slight vibration having an amplitude of 0.5 mm at a frequency of 15 Hz.

In each sample, the fatigue wear amount and the tightening rate were calculated from the radial dimension D after the fatigue test. The fatigue wear amount of each sample is calculated as the amount of change in the radial dimension D before and after the fatigue test. The tightening rate of the sample whose dimension D after the fatigue test is smaller than the distance L is calculated as a negative value. Table 2 shows the fatigue wear amount and tightening rate of each sample.

It was confirmed that in each of the samples S5 to S7 according to the examples, the amount of fatigue wear was small and the sealing property was maintained even after the test. On the other hand, in each of the samples S1 to S4 according to the comparative example, the amount of fatigue wear was large. In particular, in the samples S1 and S2, the tightening rate after the test became negative, and it was confirmed that the sealing property was completely lost.

4. Other Embodiments Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present invention. Is.

For example, in the seal ring 10, even if the first angle θa of the first inclined surface 122 in the first deformed portion 12 and the second angle θb of the second inclined surface 132 in the second deformed portion 13 are different from each other. good. Also in this case, it is preferable that the angles θa and θb of the inclined surfaces 122 and 132 of the deformed portions 12 and 13 are all 30 ° or more and 40 ° or less.

Further, in the seal ring 10, the angles θa and θb of the inclined surfaces 122 and 132 of the deformed portions 12 and 13 may not be constant, and may be continuously changed, for example. That is, the cross-sectional shape of the inclined surfaces 122 and 132 of the deformed portions 12 and 13 does not have to be linear, and may be, for example, a convex or concave curved shape.

Further, in the seal ring 10, the radius of curvature Ra of the outer peripheral surface 121 in the first deformed portion 12 and the radius of curvature Rb of the inner peripheral surface 131 in the second deformed portion 13 may be different from each other. Further, the cross sections of the outer peripheral surface 121 and the inner peripheral surface 131 do not have to be arcuate, and may be curved, for example, in which the radii of curvature Ra and Rb continuously change.

In addition, the shape of the seal ring 10 does not have to be strictly symmetrical with respect to the plane F. For example, in the seal ring 10, the outer peripheral surface 121 and the inner peripheral surface 131 may be displaced to one side of the pair of side surfaces 111. In this case, the angles θa of the first inclined surface 122 may be different from each other, and the angles θa of the second inclined surface 132 may be different from each other.

Further, the seal ring 10 can obtain the same effect as described above when used not only for sealing oil but also for sealing liquids and gases other than oil. Therefore, the seal ring 10 can be used not only for hydraulic equipment but also for, for example, hydraulic equipment using water pressure and pneumatic equipment using air pressure.

10 ... Seal ring 11 ... Flat portion 111 ... Side surface 12 ... First deformed portion 121 ... Outer peripheral surface 122 ... First inclined surface 13 ... Second deformed portion 131 ... Inner peripheral surface 132 ... Second inclined surface 20 ... Shaft 21 ... Groove portion 30 ... Housing

Claims (5)

A seal ring for sealing oil,
It is formed of an elastic body having a tensile elastic modulus of 90 MPa or more at 25 ° C.
A flat portion with a pair of side surfaces extending along the radial direction,
A pair of first inclined surfaces extending from the radial outer end of the pair of side surfaces toward the outside and the outer end of the pair of first inclined surfaces are mutually close to each other. A first deformed portion having an outer peripheral surface that is connected and projects outward.
A pair of second inclined surfaces extending inwardly toward the inside from the inner end portion of the pair of side surfaces in the radial direction and the inner end portion of the pair of second inclined surfaces mutually. A second deformed portion having an inner peripheral surface that is connected and projects inwardly.
Equipped with
The outer peripheral surface or the inner peripheral surface is a sliding surface .
The first radius of curvature of the outer peripheral surface is 1.37 mm or less, and the second radius of curvature of the inner peripheral surface is 1.37 mm or less.
Seal ring. The seal ring according to claim 1.
The total radial dimension of the flat portion, the first deformed portion, and the second deformed portion is D, the radial dimension of the flat portion is d11, and the radial dimension of the first deformed portion is Assuming that the dimension is d12 and the radial dimension of the second deformed portion is d13, it is assumed.
0.2 × D ≦ d11 ≦ 0.56 × D
0.22 × D ≦ d12 ≦ 0.4 × D
0.22 × D ≦ d13 ≦ 0.4 × D
A seal ring that satisfies the relationship. The seal ring according to claim 1 or 2.
The first angle formed by the pair of first inclined surfaces and the pair of side surfaces is 30 ° or more and 40 ° or less.
A seal ring having a second angle formed by the pair of second inclined surfaces and the pair of side surfaces of 30 ° or more and 40 ° or less. The seal ring according to any one of claims 1 to 3.
The first radius of curvature of the outer peripheral surface is 0.64 mm or more, and the outer peripheral surface has a first radius of curvature of 0.64 mm or more.
A seal ring having a second radius of curvature of the inner peripheral surface of 0.64 mm or more . The seal ring according to any one of claims 1 to 4.
A seal ring having a shore A hardness of 80 or more at 25 ° C. of the elastic body.

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