Oil seals, shock absorbers

Abstract

To provide an oil seal or the like that can improve pressure resistance without worsening the moldability of the sealing portion provided on the inner circumference. [Solution] An oil seal disposed within a cylinder portion to seal the gap between a rod and a cylinder portion, comprising an annular member disposed around the rod and a sealing portion provided around the annular member, wherein the sealing portion has a first part provided on the first axial side with respect to the annular member, a second part provided on the second axial side, and a connecting part connecting the first part and the second part inside the annular member, and the inner circumference of the annular member has a minimum part where the gap with the outer surface of the rod is minimized, and a recess recessed from the minimum part such that the gap with the outer surface of the rod is larger than the minimum part, the oil seal.

Description

Technical Field

[0001] The present invention relates to an oil seal and a shock absorber.

Background Art

[0002] For example, the shock absorber described in Patent Document 1 is configured as follows. A damper cylinder is erected in an outer tube while holding its upper end by a rod guide. An oil seal fitted to the inner peripheral surface of the outer tube from above and a piston rod are inserted through the rod guide into the damper cylinder. The oil seal is held sandwiched between the rod guide and an end plate. The oil seal is formed by fixing a seal member to a flat metal reinforcing ring. The seal member forms two lip portions that slidably contact the outer peripheral surface of the piston rod on the inner peripheral side of the metal reinforcing ring. A tightening ring is externally fitted to the outer peripheral side of these lip portions, and a check lip portion that abuts against a stepped portion of the rod guide is formed on the lower surface side of the metal reinforcing ring. Further, an outer peripheral lip portion that faces into an annular recess of the rod guide and abuts against the inner peripheral surface of the outer tube with an interference fit is formed on the outer circumference of the metal reinforcing ring of the oil seal, and an annular seal portion that abuts against the inner peripheral surface of the outer tube with an interference fit is formed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Oil seals are required to maintain their function of sealing oil and gas inside the cylinder even when the pressure inside the cylinder increases. To improve pressure resistance, one option is to reduce the gap between the inner circumference of the metal reinforcing ring and the outer surface of the rod. On the other hand, if the inner diameter of the metal reinforcing ring is reduced to reduce the gap, the moldability when forming the two lip portions that slide against the outer surface of the rod deteriorates. The present invention aims to provide an oil seal or the like that can improve pressure resistance without worsening the moldability of the sealing portion provided on the inner circumference. [Means for solving the problem]

[0005] The present invention, completed with this objective in mind, is an oil seal disposed in a cylinder portion to seal the gap between a rod and the cylinder portion, comprising an annular member disposed around the rod and a sealing portion provided around the annular member, wherein the sealing portion has a first part provided on the first axial side of the rod with respect to the annular member, a second part provided on the second axial side, and a connecting portion connecting the first part and the second part inside the annular member, and the inner circumference of the annular member has a minimum part where the gap with the outer surface of the rod is minimized and a recess recessed from the minimum part such that the gap with the outer surface of the rod is larger than the minimum part, thus forming an oil seal. [Effects of the Invention]

[0006] According to the present invention, pressure resistance can be improved without worsening the moldability of the sealing portion provided on the inner circumference. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows an example of a schematic configuration of a suspension system according to the first embodiment. [Figure 2] This is an enlarged view of part II of Figure 1. [Figure 3] This figure shows an example of the shape of the ring when viewed from the second side in the axial direction. [Figure 4]This figure shows an example of a cross-section of the connection between the inner circumference of the ring and the seal portion. [Figure 5] This figure shows an example of a partial cross-section of an oil seal according to the second embodiment. [Figure 6] This figure shows an example of the shape of the oil seal ring according to the third embodiment when viewed from the second side in the axial direction. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described in detail below with reference to the attached drawings. <First Embodiment> Figure 1 shows an example of a schematic configuration of the suspension device 1 according to the first embodiment. Figure 2 is an enlarged view of part II of Figure 1. The suspension system 1 is a suspension used in four-wheeled vehicles such as passenger cars, and as shown in Figure 1, it comprises a hydraulic shock absorber 2 and a coil spring 3 positioned outside the shock absorber 2. The suspension system 1 also includes a lower spring seat 4 that supports the first axial end (lower side in Figure 1) of the rod 20, which will be described later, in the coil spring 3. The suspension system 1 also includes an upper spring seat 5 that supports the second axial end (upper side in Figure 1) of the rod 20 in the coil spring 3.

[0009] Furthermore, the suspension device 1 is equipped with a vehicle-side bracket 6 attached to the second axial end of the rod 20 for mounting the suspension device 1 to the vehicle. The suspension device 1 is also equipped with a wheel-side bracket 7 fixed to the first axial end of the rod 20 in the cylinder section 10 (described later) for mounting the suspension device 1 to the wheel. The suspension device 1 is also equipped with a dust cover 8 that covers at least a portion of the cylinder section 10 and the rod 20.

[0010] In the following, the axial direction of the rod 20 may be simply referred to as the "axial direction." The axial direction is also the direction of the centerlines of the cylindrical inner cylinder 11 and outer cylinder 12, which will be described later. The first side in the axial direction (lower side in Figure 1) and the second side in the axial direction (upper side in Figure 1) may be simply referred to as the "first side" and the "second side," respectively. The direction intersecting the axial direction (for example, the orthogonal direction) may be referred to as the "radial direction." In the radial direction, the side of the inner cylinder 11 that is on the centerline may be simply referred to as the "inside," and the side that is away from the centerline may be simply referred to as the "outside." The direction around the axis of the rod 20 may be simply referred to as the "circumferential direction."

[0011] The following provides a detailed description of buffer device 2. The shock absorber 2 comprises a cylinder portion 10 for containing oil, and a rod 20 whose second end protrudes from the cylinder portion 10 and whose first end is inserted into the cylinder portion 10. The shock absorber 2 also comprises a piston portion 30 provided at the first end of the rod 20 and a bottom portion 40 provided at the first end of the cylinder portion 10. Furthermore, the shock absorber 2 comprises a rebound sheet 50 fixed to the rod 20 and a rebound rubber 51 positioned on the second side of the rebound sheet 50 to mitigate the impact when the rod 20 extends.

[0012] The cylinder section 10 comprises a thin-walled cylindrical inner cylinder 11, an outer cylinder 12 positioned outside the inner cylinder 11, and a bottom cover 13 that closes the first end of the outer cylinder 12. The inner cylinder 11 and the outer cylinder 12 are positioned so that the direction of the centerlines of the cylinders coincides with the axial direction. The cylinder section 10 forms a reservoir chamber R between the outer circumferential surface of the inner cylinder 11 and the inner circumferential surface of the outer cylinder 12. The reservoir chamber R is filled with oil on the first side and gas on the second side.

[0013] Furthermore, the cylinder section 10 includes a rod guide 14 that supports the rod 20 so that it can move in the axial direction, and an oil seal 100 that prevents oil leakage from the cylinder section 10 and the entry of foreign matter into the cylinder section 10. The cylinder section 10 also includes a bump stopper cap 15 attached to the second end of the outer cylinder 12. The rod guide 14 and the oil seal 100 will be described in detail later.

[0014] The rod 20 is a rod-shaped member extending in the axial direction. The rod 20 holds the piston portion 30 on the first side. Also, the rod 20 is connected to, for example, a vehicle body via a vehicle body side bracket 6 on the second side.

[0015] The piston portion 30 includes a piston 31, a valve group 32 that closes the end on the first side in a part of the plurality of oil passages formed in the piston 31, and a valve group 33 that closes the end on the second side in a part of the oil passages formed in the piston 31. The piston 31 contacts the inner peripheral surface of the inner cylinder 11 via a seal member provided on its outer peripheral surface, and divides the space filled with oil in the inner cylinder 11 into a first oil chamber Y1 on the first side of the piston 31 and a second oil chamber Y2 on the second side of the piston 31.

[0016] As shown in FIG. 1, the bottom portion 40 includes a valve body 41 having a plurality of oil passages penetrating in the axial direction, a valve 42 provided on the first side of the valve body 41, and a valve 43 provided on the second side of the valve body 41. The valve body 41 of the bottom portion 40 divides the first oil chamber Y1 and the reservoir chamber R.

[0017] 〔Rod guide 14〕 The rod guide 14 includes a thin-walled cylindrical guide 60 disposed inside and a guide case 70 that holds the guide 60 inside.

[0018] The inner diameter of the guide 60 is set to be slightly larger than the outer diameter of the rod 20 inserted inside. For example, the inner diameter of the guide 60 is 0.1 mm to 1 mm larger than the outer diameter of the rod 20. Since the inner peripheral surface of the guide 60 contacts the outer peripheral surface 21 of the rod 20, the guide 60 is formed of a material having better wear resistance than the guide case 70. [[ID=​​The guide case 70 has an inner cylindrical portion 71 provided on the inside and an outer cylindrical portion 72 provided on the outside of the inner cylindrical portion 71. The inner cylindrical portion 71 and the outer cylindrical portion 72 are integrally molded so that the outer circumferential surface of the second side portion of the inner cylindrical portion 71 and the inner circumferential surface of the first side portion of the outer cylindrical portion 72 are joined together.

[0020] A guide 60 is fitted inside the inner cylindrical portion 71. The outer diameter of the inner cylindrical portion 71 is molded to be equal to the inner diameter of the inner cylinder 11. The inner cylindrical portion 71 is positioned inside the inner cylinder 11 with its outer circumferential surface in contact with the inner circumferential surface of the inner cylinder 11.

[0021] The outer diameter of the outer cylindrical portion 72 is formed to be equal to the inner diameter of the second end of the outer cylinder 12. The outer cylindrical portion 72 is positioned between the rod 20 and the outer cylinder 12, with its outer circumferential surface in contact with the inner circumferential surface of the outer cylinder 12 in the radial direction. The outer cylindrical portion 72 is also positioned between the inner cylinder 11 and the oil seal 100 in the axial direction. The outer cylindrical portion 72 positions the inner cylinder 11 so that it does not move to the second side.

[0022] The outer cylindrical portion 72 has an inner recess 721 formed at the second end on the inside, which is recessed from the second end face 720, and an outer recess 722 formed at the second end on the outside, which is recessed from the second end face 720. The second opening in the inner recess 721 is chamfered. The outer recess 722 is recessed in a substantially cylindrical shape and has an inclined surface 724 formed such that the outer diameter of the second end of the outer cylindrical portion 72 gradually decreases as it moves towards the second side.

[0023] The outer cylindrical portion 72 has a flow path 75 formed in it that returns the oil that has passed through the gap between the rod 20 and the guide 60 to the second side of the inner cylindrical portion 71 of the guide case 70 back to the reservoir chamber R. As described above, the guide case 70 can be exemplified by being molded from metals such as steel or non-metallic materials such as polytetrafluoroethylene.

[0024] [Oil seal 100] The oil seal 100 has an annular ring 110 made of a metal such as steel, and a sealing portion 130 made of a material with a low modulus of elasticity such as synthetic rubber. The ring 110 holds the sealing portion 130.

[0025] The ring 110 is annular in shape, with an inner diameter larger than the outer diameter of the rod 20 and an outer diameter smaller than the inner diameter of the second end of the outer cylinder 12. For example, the outer diameter of the ring 110 is 0.5 mm to 3 mm smaller than the inner diameter of the second end of the outer cylinder 12. The ring 110 has an opening-side end face 111 which is the end face on the second opening end 12a side of the outer cylinder 12 (in other words, the second side end face) and an inner-side end face 112 which is the end face on the side where the piston portion 30 is located (in other words, the first side). The ring 110 also has an outer surface 113 which is an outer surface provided on the outside and extends in a direction intersecting the opening-side end face 111 and the inner-side end face 112. The ring 110 also has an inner circumference portion 120 which is the part on the outer circumference 21 side of the rod 20 (in other words, the inner part). The inner circumference portion 120 will be described in detail later.

[0026] The seal portion 130 is provided on the first side of the ring 110, has a wedge-shaped cross-section, and includes a seal lip portion 131 that is pressed by an annular spring and adheres tightly to the entire circumference of the outer surface 21 of the rod 20. The seal portion 130 is also provided on the second side of the ring 110 and includes a dust lip portion 132 that adheres tightly to the entire circumference of the outer surface 21 of the rod 20 to suppress the intrusion of dust from the outside. The seal portion 130 also has a connecting portion 133 that connects the seal lip portion 131 and the dust lip portion 132 inside the ring 110.

[0027] Furthermore, the seal portion 130 has an outer peripheral seal portion 134 that protrudes to the first side from the outer circumference of the ring 110 over its entire circumference. Before the oil seal 100 is assembled into the outer cylinder 12, the outer peripheral seal portion 134 is cylindrical and its outer diameter is larger than the outer diameter of the ring 110. The outer peripheral seal portion 134 is positioned to fit into the outer recess 722 of the guide case 70 of the rod guide 14 and contacts the inner circumferential surface of the second end of the outer cylinder 12, thereby suppressing oil leakage from the gap between the outer circumferential surface of the guide case 70 and the inner circumferential surface of the outer cylinder 12. In addition, the inner portion of the outer peripheral seal portion 134 contacts the inclined surface 724 of the guide case 70.

[0028] Furthermore, the seal portion 130 has a central seal portion 135 that protrudes over the entire circumference of the ring 110 from the inner circumference portion 120 in a direction that is axially inclined to the first side and outward. The central seal portion 135 contacts the inner recess 721 of the outer cylindrical portion 72 of the guide case 70, thereby suppressing the flow of oil or gas filled in the reservoir chamber R through the flow path 75 inward. The central seal portion 135, the seal lip portion 131, and the outer peripheral seal portion 134 are integrally molded to be joined at a point first to the ring 110.

[0029] In the oil seal 100 according to this embodiment, the inner end face 112 of the ring 110 is covered by a seal lip portion 131, a central seal portion 135, and an outer peripheral seal portion 134. On the other hand, the inner portion of the opening end face 111 of the ring 110 is covered by a dust lip portion 132, while the outer portion is not covered by a seal portion 130.

[0030] An example of an oil seal 100 being formed using compression molding is to set a ring 110 and a predetermined amount of material for the sealing portion 130, such as synthetic rubber, in a heated mold, and then vulcanize the synthetic rubber by pressurizing and heating it in a molding machine, thereby forming the sealing portion 130 around the ring 110.

[0031] The inner circumference 120 of the ring 110 will be described below. Figure 3 shows an example of the shape of the ring 110 when viewed from the second side in the axial direction. Figure 4 shows an example of a cross-section of the connection portion 133 between the inner circumference 120 of the ring 110 and the seal portion 130. The inner circumference 120 is a surface that extends in a direction intersecting the opening end face 111 and the inner end face 112 (see Figure 2) when viewed in the axial direction, and has a minimum portion 121 where the gap with the outer circumferential surface 21 of the rod 20 is minimized. The inner circumference 120 also has a recess 122 that is recessed from the minimum portion 121 such that the gap with the outer circumferential surface 21 of the rod 20 is larger than the minimum portion 121.

[0032] In the inner circumference portion 120 according to the first embodiment, when viewed in the axial direction, the minimum portion 121 is in the shape of an arc centered on the axis of the rod 20. Multiple minimum portions 121 are provided at equal intervals in the circumferential direction (seven in Figure 3). The multiple minimum portions 121 lie on a virtual circle centered on the axis of the rod 20.

[0033] In the inner circumference portion 120 according to the first embodiment, the recess 122 is rectangular when viewed in the axial direction. For example, the recess 122 is formed by two side edges 123 extending radially from each of the circumferential ends of adjacent minimum portions 121, and a base edge 124 connecting the outer ends of the two side edges 123. Multiple recesses 122 are provided between the two minimum portions 121, and are provided at equal intervals in the circumferential direction (the same number as the minimum portions 121). Note that the side edges 123 do not necessarily extend radially; for example, the outer portion of one of the two side edges 123 may approach the other minimum portion 121, so as to form an obtuse angle with the tangent to the minimum portion 121 passing through its circumferential end. Also, the base edge 124 does not necessarily have to be a straight line; for example, when viewed in the axial direction, it may be an arc shape centered on the axis of the rod 20.

[0034] The connecting portion 133 of the seal portion 130 is provided between the inner circumference 120 of the ring 110 and the outer circumference 21 of the rod 20. The connecting portion 133 is also provided between the seal lip portion 131 (see Figure 2) and the dust lip portion 132 (see Figure 2). The inner diameters of the seal lip portion 131 and the dust lip portion 132 are smaller than the diameter of the outer circumference 21 of the rod 20 so that they contact the outer circumference 21 of the rod 20. In contrast, the connecting portion 133 has an inner surface 141 on its inner side, which is circular in shape when viewed in the axial direction and is parallel to the axial direction, and the diameter of the inner surface 141 is larger than the diameter of the outer circumference 21 of the rod 20.

[0035] The portion of the connecting portion 133 that is outside the inner surface 141 is molded to fill the gap with the inner circumference 120 of the ring 110. In other words, the connecting portion 133 is formed in the compression molding process that forms the oil seal 100 by filling the gap between the mold and the inner circumference 120 of the ring 110 with the material for the seal portion 130. To put it another way, the gap between the mold and the inner circumference 120 of the ring 110, which forms the connecting portion 133, becomes a flow path for the material that forms the seal lip portion 131 and the dust lip portion 132.

[0036] As described above, the oil seal 100 comprises a ring 110 (an example of an annular member) arranged around the rod 20 and a seal portion 130 provided around the ring 110. The seal portion 130 has a seal lip portion 131 (an example of a first portion) provided on the first axial side of the ring 110 and a dust lip portion 132 (an example of a second portion) provided on the second axial side. The seal portion 130 also has a connecting portion 133 that connects the seal lip portion 131 and the dust lip portion 132 inside the ring 110. The inner circumference portion 120 of the ring 110 has a minimum portion 121 where the gap with the outer circumferential surface 21 (an example of an outer surface) of the rod 20 is minimized, and a recess 122 that is recessed from the minimum portion 121 so that the gap with the outer circumferential surface 21 of the rod 20 is larger than the minimum portion 121.

[0037] In the oil seal 100 configured as described above, pressure resistance can be improved without worsening the moldability of the two lip portions provided around the inner circumference 120, namely the seal lip portion 131 and the dust lip portion 132. This is for the following reasons.

[0038] Here, as the ring according to the first comparative example, we consider one in which the inner circumference is circular and the radius is the same as the radius of the base 124 of the recess 122 compared to ring 110. In other words, in the ring according to the first comparative example, the gap between the inner circumference and the outer surface 21 of the rod 20 is the same as the gap between the base 124 of the recess 122 of the inner circumference 120 of ring 110 and the outer surface 21, along the entire circumference. Compared with the ring according to the first comparative example, the ring 110 according to the first embodiment has a minimum portion 121 where the gap with the outer surface 21 is minimized, and therefore has superior pressure resistance compared to the ring according to the first comparative example. In other words, ring 110 has higher backup performance than the ring according to the first comparative example (in other words, the amount of operation of the seal lip portion 131 is reduced). Therefore, ring 110 has high performance in suppressing oil leakage from the cylinder portion 10 to the outside when the pressure inside the cylinder portion 10 increases (in other words, high sealing performance).

[0039] Furthermore, to improve the sealing performance of the oil seal 100, it is conceivable to increase the thickness of the seal lip portion 131 and the dust lip portion 132. However, increasing the thickness of the seal lip portion 131 and the dust lip portion 132 increases the contact force with the outer surface 21 of the rod 20, which may worsen the ride comfort in the initial stages after the suspension system 1 is installed on the vehicle. In the oil seal 100 according to the first embodiment, the sealing performance can be improved without increasing the thickness of the seal lip portion 131 and the dust lip portion 132.

[0040] As a second comparative example, we consider a ring that differs from ring 110 in that the minimum portion 121 is formed around its entire circumference and it does not have a recess 122. In other words, in the ring of the second comparative example, the gap between the inner circumference and the outer surface 21 of the rod 20 is the same around its entire circumference as the gap between the minimum portion 121 of the inner circumference 120 of ring 110 according to the first embodiment and the outer surface 21 of the rod 20. With the ring of the second comparative example, the gap between the inner circumference and the outer surface 21 of the rod 20 is smaller than that of the ring of the first comparative example, so the sealing performance is higher. However, in the ring of the second comparative example, the gap between the mold and the inner circumference when forming the oil seal 100 is smaller, so the flow path of the material forming the seal lip portion 131 and the dust lip 132 becomes narrower. As a result, the formability of the seal portion 130 deteriorates. In contrast, in the ring 110 according to the first embodiment, the gap between the mold and the inner circumference 120 when forming the oil seal 100 at the location where the recess 122 is formed is larger than that of the ring according to the second comparative example. As a result, the ring 110 according to the first embodiment can suppress deterioration of the formability of the seal portion 130 due to improved sealing performance.

[0041] Here, when viewed in the axial direction, the smallest part 121 is arc-shaped with respect to the axis of the rod 20, and the recess 122 is rectangular. This makes it possible to increase the area of ​​the recess 122 compared to, for example, when the recess 122 is triangular, thereby improving the moldability of the seal portion 130.

[0042] Furthermore, the ring 110 is flat and its surfaces are arranged so that they intersect in the axial direction. This allows the ring 110 to reliably provide a backup function for the seal lip portion 131. Furthermore, the seal portion 130 is provided on the outer circumference of the ring 110 and further includes an outer peripheral seal portion 134 that seals the gap between the ring 110 and the inner circumferential surface (an example of the inner surface) of the second end of the outer cylinder 12 of the cylinder portion 10. As a result, the seal portion 130 can suppress oil leakage from the gap between the outer circumferential surface of the rod guide 14 and the inner circumferential surface of the outer cylinder 12.

[0043] <Second Embodiment> Figure 5 shows an example of a partial cross-section of the oil seal 200 according to the second embodiment. The oil seal 200 according to the second embodiment differs from the oil seal 100 according to the first embodiment in that the inner circumference 220 of the ring 210 corresponds to the inner circumference 120 of the ring 110. The differences from the first embodiment will be described below. The same reference numerals are used for the same parts in the first and second embodiments, and their detailed descriptions will be omitted.

[0044] The inner circumference portion 220 of the second embodiment differs from the inner circumference portion 120 of the first embodiment in that the recess 222 corresponds to the recess 122. As shown in Figure 5, the recess 222 is an arc shape with a curvature greater than that of the minimum portion 121 when viewed in the axial direction. In other words, the recess 222 is formed by an arc-shaped portion 225 that passes through each of the circumferential ends of adjacent minimum portions 121. It can be illustrated that the distance of the arc-shaped portion 225 from the axis of the rod 20 is the same as the distance from the axis of the rod 20 to the bottom edge 124 of the ring 110 according to the first embodiment.

[0045] In the oil seal 200 configured as described above, the connecting portion 133 is formed in the compression molding process that forms the oil seal 200 by filling the gap between the mold and the inner circumference 220 of the ring 210 with the material of the sealing portion 130. Furthermore, in the oil seal 200, the pressure resistance can be improved without worsening the moldability of the two lip portions provided around the inner circumference 220, namely the sealing lip portion 131 and the dust lip portion 132.

[0046] <Third Embodiment> Figure 6 shows an example of the shape of the ring 310 of the oil seal 300 according to the third embodiment when viewed from the second side in the axial direction. The oil seal 300 according to the third embodiment differs from the oil seal 100 according to the first embodiment in that the inner circumference 320 of the ring 310 corresponds to the inner circumference 120 of the ring 110. The differences from the first embodiment will be described below. The same reference numerals are used for the same parts in the first and third embodiments, and their detailed descriptions will be omitted.

[0047] The inner circumference 320 has a minimum portion 321 and a recess 322, which correspond to the minimum portion 121 and recess 122 of the inner circumference 120 according to the first embodiment. As shown in Figure 6, when viewed in the axial direction, the minimum portion 321 is a plurality of points 325 on a virtual circle centered on the axis of the rod 20, and the recess 322 is a triangle with two of the plurality of points 325 as its vertices. In other words, the inner circumference 120 is a surface that extends in a direction intersecting the opening side end face 111 and the inner side end face 112 (see Figure 2), and also has a surface that, when viewed in the axial direction, forms a regular polygon (for example, a regular nonagon as shown in Figure 6) centered on the axis of the rod 20. As shown in Figure 6, when the sides of the regular polygon are called sides 327 and the corners are called corners 328, the minimum portion 121 is the central part of side 327, and the recess 322 is formed by the corner 328 and side 327.

[0048] In the oil seal 300 configured as described above, the connecting portion 133 is formed in the compression molding process that forms the oil seal 300 by filling the gap between the mold and the inner circumference 320 of the ring 310 with the material of the sealing portion 130. Furthermore, in the oil seal 300, the pressure resistance can be improved without worsening the moldability of the two lip portions provided around the inner circumference 320, namely the sealing lip portion 131 and the dust lip portion 132. [Explanation of Symbols]

[0049] 1...Suspension device, 2...Buffing device, 10...Cylinder section, 11...Inner cylinder, 12...Outer cylinder, 14...Rod guide, 20...Rod, 21...Outer surface, 30...Piston section, 100, 200, 300...Oil seal, 110, 210, 310...Ring (example of annular member), 120, 220, 320...Inner circumference, 121, 321...Minimum part, 122, 222, 322...Recess, 130...Seal section, 131...Seal lip section (example of first part), 132...Dust lip (example of second part), 133...Connecting section, 134...Outer seal section

Claims

1. An oil seal disposed within a cylinder portion to seal the gap between the rod and the cylinder portion, An annular member arranged around the aforementioned rod, A sealing portion provided around the annular member, Equipped with, The sealing portion has a first portion provided on the first axial side of the rod with respect to the annular member, a second portion provided on the second axial side, and a connecting portion that connects the first portion and the second portion inside the annular member. The inner circumference of the annular member has a minimum portion where the gap with the outer surface of the rod is minimized, and a recess that is recessed from the minimum portion such that the gap with the outer surface of the rod is larger than the minimum portion. Oil seal.

2. When viewed in the axial direction, the smallest part is arc-shaped with respect to the axis of the rod, and the recess is rectangular. The oil seal according to claim 1.

3. When viewed in the axial direction, the smallest portion is arc-shaped with respect to the axis of the rod, and the recess is arc-shaped with a curvature greater than that of the smallest portion. The oil seal according to claim 1.

4. When viewed in the axial direction, the smallest part is a plurality of points on a virtual circle centered on the axis of the rod, and the recess is a triangle with two of the plurality of points as its vertices. The oil seal according to claim 1.

5. The annular member is flat, and its surface is arranged so as to intersect in the axial direction. The oil seal according to claim 1.

6. The sealing portion further comprises an outer peripheral sealing portion provided on the outer circumference of the annular member, which seals the gap with the inner surface of the cylinder portion. The oil seal according to claim 1.

7. The cylinder section, which contains the working fluid, A rod having one end connected to the piston and the other end exposed to the outside of the cylinder, An oil seal according to any one of claims 1 to 6, which is disposed within the cylinder portion and seals the gap between the rod and the cylinder portion, A shock absorber equipped with a shock absorber.

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