Hydraulic Equipment

Abstract

To provide a liquid pressure device which can achieve good sealability without impairing assemblability.SOLUTION: A liquid pressure device includes: a cylindrical outer shell 4; a rod 3 which is inserted into the outer shell 4 so as to be movable in an axial direction; an annular rod guide 5 which is fitted in an inner periphery of one end of the outer shell 4 and in which the rod 3 is inserted into an inner periphery and a taper surface t is formed at the atmosphere side of an outer periphery; and a seal member 6 which has an annular insert metal 7 laminated on the rod guide 5 and an annular outer periphery seal 8 which is provided at an outer periphery of the insert metal 7 and is pressed against the taper surface t to adhere to the inner periphery of the outer shell 4 and which is inserted into the inner periphery of the outer shell 4. The outer periphery seal 8 has an annular first lip 8b, which contacts with the inner periphery of the outer shell 4 when the outer periphery seal 8 contacts with the taper surface t, at an outer periphery. The first lip 8b does not contact with the inner periphery of the outer shell 4 in a state where the outer periphery seal 8 does not contact with the taper surface t.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to hydraulic equipment. [Background technology]

[0002] Generally, a twin-cylinder hydraulic shock absorber is provided with a rod guide that closes the open end of the cylinder and the open end of the outer cylinder that covers the cylinder, and supports a rod that is inserted movably into the cylinder.In addition, a sealing member with a seal on both the inner and outer periphery of the annular insert metal is layered on this rod guide, keeping the inside of the hydraulic shock absorber oil-tight.

[0003] In detail, the sealing member comprises an annular insert metal, an annular outer peripheral seal formed of rubber welded to the outer periphery of the cylinder-side end face of the insert metal and abutting against the inner periphery of the outer tube, and a seal lip and dust lip formed of rubber welded to the inner periphery of the insert metal and sliding against the outer periphery of the rod, and is fitted into the outer tube while being stacked on the rod guide.

[0004] The rod guide has a tapered surface on its outer periphery that is gradually reduced in diameter at its end on the atmosphere side, opposite the cylinder, and an annular gap that accommodates an outer periphery seal is formed between the tapered surface and the inner circumferential surface of the outer cylinder. When a seal member is fitted onto the inner periphery of the outer cylinder and an insert metal is laminated onto the atmosphere side end face of the rod guide, the outer periphery seal is compressed between the tapered surface and the inner circumferential surface of the outer cylinder and comes into close contact with them, allowing the seal member to seal between the rod guide and the outer cylinder.

[0005] In such hydraulic equipment, the cross section of the outer seal is rectangular, and the outer periphery of the outer seal is in close contact with the inner periphery of the outer cylinder, but the distribution of the contact surface pressure on the outer periphery of the outer seal with the outer cylinder is uniform. To achieve good sealing, it is preferable for the contact surface pressure to have a moderate gradient. Therefore, in order to improve the sealing performance of the outer seal, hydraulic equipment has been proposed in which a lip consisting of multiple protrusions is provided around the outer periphery of the outer seal (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Utility Model Application Publication No. 3-51246 Summary of the Invention [Problem to be solved by the invention]

[0007] As mentioned above, providing multiple lips on the outer periphery of the outer seal improves sealing performance, but in order to increase the contact surface pressure at the lips, the outer diameter of the lips is made larger than the inner diameter of the outer tube, making it difficult to insert the sealing member into the outer tube and reducing assembly ease.

[0008] Furthermore, when the seal member is inserted into the outer cylinder, the lip rubs against the inner peripheral surface of the outer cylinder, which may cause the lip to deteriorate and impair the sealing performance.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a hydraulic device that can achieve good sealing performance without impairing assembly ease. [Means for solving the problem]

[0010] In order to achieve the above-mentioned object, the hydraulic device of the present invention comprises a cylindrical outer shell, a rod that is inserted into the outer shell so as to be axially movably, a ring-shaped rod guide that is fitted into the inner periphery of one end of the outer shell, through which the rod is inserted and that has a tapered surface on the atmospheric side of the outer periphery, a sealing member that is inserted into the inner periphery of one end of the outer shell, the sealing member having an annular insert metal that is laminated on the rod guide, and an annular outer periphery seal that is provided on the outer periphery of the insert metal and is pressed against the tapered surface to be in close contact with the inner periphery of the outer shell, and the outer periphery seal has an annular first lip on its outer periphery that abuts against the inner periphery of the outer shell when the outer periphery seal abuts against the tapered surface, and the first lip does not abut against the inner periphery of the outer shell when the outer periphery seal is not abutting against the tapered surface.

[0011] In hydraulic equipment configured in this manner, the first lip does not provide resistance when inserting the seal member into the outer shell, allowing the seal member to be easily inserted into the outer shell, and the first lip is not damaged when the outer seal is inserted into the outer shell. Furthermore, in hydraulic equipment configured in this manner, the outer seal expands in diameter when it abuts on the tapered surface, pressing the first lip against the inner circumference of the outer shell, thereby increasing the contact surface pressure at the first lip and improving sealing performance.

[0012] The outer circumferential seal has a plurality of annular corners, and the first lip is formed at the annular corner closest to the atmosphere among the annular corners, and a second lip that is in close contact with the inner periphery of the outer shell is formed at the annular corners other than the annular corner that forms the first lip. There areAccording to a hydraulic device configured in this manner, in addition to the first lip, a second lip is provided that increases the contact surface pressure with the inner periphery of the outer shell, thereby further improving sealing performance, and since no large frictional force is generated between the second lip and the outer shell when inserting the seal member into the outer shell, assembly is not impaired. Furthermore, according to a hydraulic device configured in this manner, the first lip and second lip are formed by forming a stepped cross section of the outer periphery of the end of the outer seal facing the inside of the outer shell on the side opposite the atmosphere, so when the seal member is removed from a mold that forms the seal member, the first lip and second lip do not get caught in the mold, and the seal member can be easily removed from the mold. Furthermore, in a hydraulic device of another invention, the outer seal has a plurality of annular corners formed by stepping the cross section of the outer periphery of the end portion facing the atmosphere inside the outer shell, and a first lip is formed at the annular corner closest to the atmosphere among the annular corners.

[0013] Furthermore, the rod guide may have an annular small diameter portion at its atmosphere side end, the small diameter portion having an outer diameter that is smaller as it approaches the atmosphere side, an outer peripheral inclined portion that forms a tapered surface on its outer periphery, and an annular portion that rises vertically from the outer peripheral inclined portion and has an outer peripheral surface that faces the inner circumference of the outer shell, and the outer peripheral seal may be housed in an annular gap between the small diameter portion and the outer shell. With a hydraulic device configured in this manner, the first lip can improve sealing performance, and the filling rate of the outer peripheral seal in the annular gap can be increased, thereby achieving stable sealing performance. [Effects of the Invention]

[0014] According to the hydraulic device of the present invention, good sealing performance can be achieved without impairing ease of assembly. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a longitudinal sectional view of a hydraulic device according to an embodiment of the present invention; [Figure 2] FIG. 2 is an enlarged vertical cross-sectional view of a seal member of the hydraulic device according to the embodiment. [Figure 3] FIG. 2 is an enlarged cross-sectional view of a seal member of the hydraulic device according to the embodiment. [Figure 4] FIG. 2 is an enlarged cross-sectional view of a sealing member stacked on a rod guide of a hydraulic device according to an embodiment. [Figure 5] FIG. 4 is a partially enlarged cross-sectional view of a hydraulic device according to a first modified example of the embodiment. [Figure 6] FIG. 10 is a partially enlarged cross-sectional view of a hydraulic device according to a second modified example of the embodiment. [Figure 7] FIG. 10 is a partially enlarged cross-sectional view of a hydraulic device according to a third modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, a hydraulic device of the present invention will be described with reference to the drawings. The hydraulic device in one embodiment is a twin-cylinder shock absorber. To function as a twin-cylinder shock absorber, the hydraulic device includes, as shown in FIG. 1 , a cylinder 1, a piston 2 slidably inserted into the cylinder 1 and dividing the interior of the cylinder 1 into a rod-side chamber R1 and a piston-side chamber R2 filled with liquid, a rod 3 movably inserted into the cylinder 1 and connected to the piston 2, a cylindrical outer shell 4 disposed on the outer periphery of the cylinder 1, a reservoir R formed by the gap between the cylinder 1 and the outer shell 4, communicating with the piston-side chamber R2, and filled with gas and liquid, a rod guide 5 closing the ends of the outer shell 4 and the cylinder 1 and slidably supporting the rod 3, and a seal member 6 stacked on the rod guide 5 to seal between the rod 3 and the outer shell 4.

[0017] Each part of the hydraulic equipment will be described in detail below. Cylinder 1 is cylindrical, and a rod guide 5, through which a rod 3 is slidably inserted, is fitted at the upper end, closing the upper end of the cylinder 1. A valve case 12 is fitted at the lower end of the cylinder 1, and the lower end of the cylinder 1 is also closed by the valve case 12.

[0018] As described above, the upper and lower ends of the cylinder 1 are closed by the rod guide 5 and the valve case 12, respectively. The piston 2 is slidably inserted into the cylinder 1, dividing the interior of the cylinder 1 into an upper rod-side chamber R1 and a lower piston-side chamber R2 in FIG. 1, and these rod-side chamber R1 and piston-side chamber R2 are filled with a liquid such as hydraulic oil.

[0019] The piston 2 is attached to the tip of the rod 3, which is the lower end in FIG. 1, of the rod 3 that is movably inserted into the cylinder 1, and has ports 2a and 2b that communicate with the rod side chamber R1 and the piston side chamber R2.

[0020] A check valve 13 is provided in port 2a of the piston 2, which allows liquid to flow only from the piston side chamber R2 to the rod side chamber R1, and a damping valve 14 is provided in port 2b of the piston 2, which allows liquid to flow only from the rod side chamber R1 to the piston side chamber R2 and provides resistance to the flow of liquid passing through.

[0021] Furthermore, an outer shell 4 is provided outside the cylinder 1, covering the cylinder 1 and forming a gap between it and the cylinder 1. The outer shell 4 has an open end (the upper end in FIG. 1) and a closed end (the lower end in FIG. 1). A reservoir R is formed in the gap between the outer shell 4 and the cylinder 1. The reservoir R is filled with a liquid and a gas such as an inert gas. When closing the lower end of the outer shell 4, a lid may be provided to close it, or the outer shell 4 may be previously formed into a closed-end cylindrical shape.

[0022] 2, the rod guide 5 is annular and includes a large-diameter portion 5a that fits around the inner periphery of the outer shell 4, a fitting portion 5b that has an outer diameter smaller than that of the large-diameter portion 5a and that protrudes from the outer-shell end of the large-diameter portion 5a, which is the lower end of the large-diameter portion 5a in FIG. 2, and is fitted into the cylinder 1, an annular small-diameter portion 5c that protrudes upward from the atmosphere-side end of the large-diameter portion 5a, which is the upper end of the large-diameter portion 5a in FIG. 2, an annular recess 5d provided on the inner periphery of the atmosphere-side end of the large-diameter portion 5a, a through-hole 5e that penetrates the large-diameter portion 5a from the lower end to the upper end of the large-diameter portion 5a and opens into the inside of the small-diameter portion 5c, and a cylindrical bushing 5f that is attached from the inner periphery of the large-diameter portion 5a to the inner periphery of the fitting portion 5b and slides against the outer periphery of the rod 3. The outer diameter of the small-diameter portion 5c decreases toward the atmosphere, and a tapered surface t is formed on the outer periphery.

[0023] When the rod guide 5 configured in this manner is fitted to the cylinder 1 and the outer shell 4, an annular gap with a triangular cross section is formed between the inner peripheral surface of the outer shell 4 and the tapered surface t on the outer periphery of the small diameter portion 5c. The opening of the through hole 5e at the outer shell side end of the rod guide 5 faces the reservoir R, and the space on the inner peripheral side of the small diameter portion 5c of the rod guide 5 and the reservoir R are in communication via the through hole 5e.

[0024] Next, the sealing member 6 includes an annular insert metal 7 stacked on the rod guide 5, an annular outer peripheral seal 8 provided on the outer periphery of the insert metal 7 at the lower end in Figure 2, which is the inner end of the outer shell, and pressed against the tapered surface t to come into close contact with the inner periphery of the outer shell 4, an annular oil seal 9 and a dust seal 10 provided on the inner periphery of the insert metal 7 and in sliding contact with the outer periphery of the rod 3, and an annular check seal 11 provided in the middle of the lower end of the insert metal 7 in Figure 2.

[0025] The insert metal 7 is annular and is laminated on the atmospheric side of the small diameter portion 5c of the rod guide 5. The outer periphery seal 8 is made of rubber and, as shown in Figs. 2 and 3, is attached to the outer periphery of the end of the insert metal 7 facing the outer shell 4, at a location that faces the tapered surface t of the small diameter portion 5c of the rod guide 5 in the axial direction. More specifically, the outer periphery seal 8 has a cross section but The main body 8a has a substantially rectangular annular shape, and a first lip 8b and a second lip 8c formed by two annular corners provided on the main body 8a by making the cross section of the outer periphery of the lower end in Figure 3, which is the end of the main body 8a facing inside the outer shell 4, step-shaped.

[0026] As described above, in the hydraulic device of this embodiment, the first lip 8b and the second lip 8c are formed by cutting off a rectangular corner of the lower outer periphery of the main body 8a of the outer periphery seal 8 in FIG. 3 to form a stepped shape. Of the annular corners provided on the main body 8a, the first lip 8b is the annular corner that is closest to the atmosphere, i.e., the annular corner that is closest to the inner side of the outer shell 4. Of the annular corners provided on the main body 8a, the second lip 8c is the annular corner other than the annular corner that forms the first lip 8b.

[0027] Before the seal member 6 is stacked on the rod guide 5, the outer diameter of the first lip 8b of the outer seal 8 is smaller than the outer diameter of the main body 8a and smaller than the inner diameter of the outer shell 4. The outer diameter of the second lip 8c is the same as the outer diameter of the main body 8a. The outer diameters of the main body 8a and the second lip 8c are smaller than the inner diameter of the outer shell 4, but may be larger than the inner diameter of the outer shell 4 as long as they can be inserted into the outer shell 4 without difficulty.

[0028] The oil seal 9 is annular and is provided inside the outer shell on the inner periphery of the insert metal 7, and is in sliding contact with the outer periphery of the rod 3 to scrape off liquid adhering to the outer periphery of the rod 3 when the rod 3 moves in the direction of retracting from the outer shell 4, thereby preventing leakage outside the outer shell 4. The dust seal 10 is annular and is provided on the atmospheric side of the inner periphery of the insert metal 7, and is in sliding contact with the outer periphery of the rod 3 to scrape off dust adhering to the outer periphery of the rod 3 when the rod 3 moves in the direction of entering the outer shell 4, thereby preventing dust from entering the outer shell 4.

[0029] The check seal 11 has a disc spring shape, and when the seal member 6 is stacked on the rod guide 5, its tip is the atmospheric-side end of the large-diameter portion 5a and abuts against the inner circumferential side of the small-diameter portion 5c, blocking communication between the annular recess 5d and the through-hole 5e. When liquid scraped off by the oil seal 9 accumulates in the annular recess 5d and the pressure therein increases, the check seal 11 bends and moves away from the large-diameter portion 5a, allowing the liquid in the annular recess 5d to pass through the through-hole 5e and be discharged into the reservoir R. Even if the pressure in the reservoir R becomes higher than the pressure in the annular recess 5d, the check seal 11 is pressed against the large-diameter portion 5a by the pressure in the reservoir R, blocking communication between the annular recess 5d and the through-hole 5e, so that liquid or gas in the reservoir R does not flow back into the annular recess 5d.

[0030] The sealing member 6 configured in this manner is manufactured, for example, by placing an insert metal 7, to which adhesive has been applied in advance, into a mold for forming the outer seal 8, oil seal 9, dust seal 10, and check seal 11, injecting rubber material into the mold, and vulcanizing and bonding each of the seals 8, 9, 10, and 11 to the insert metal 7.

[0031] The seal member 6 is inserted into the inner periphery of the open end, which is one end of the outer shell 4 in a state in which the rod guide 5 is housed, and is stacked on the rod guide 5. After that, the open end of the outer shell 4 is crimped toward the inner periphery, and the seal member 6 is sandwiched between the crimped portion 4a and the rod guide 5 and fixed to the outer shell 4. In this way, the seal member 6 fixed to the outer shell 4 seals the cylinder 1 and the open end of the outer shell 4, maintaining the inside of the cylinder 1 and the outer shell 4 in a sealed state.

[0032] The lower end of the cylinder 1 is fitted and sealed with a valve case 12, which separates the reservoir R from the piston-side chamber R2. The valve case 12 is sandwiched and fixed between the bottom of the lower end of the outer shell 4 and the cylinder 1. That is, in this embodiment, the valve case 12, cylinder 1, rod guide 5, and seal member 6 are inserted into the outer shell 4 in this order, and the upper open end of the outer shell 4 in FIG. 1 is crimped from the outer periphery toward the inner periphery, thereby fixing each component inserted into the outer shell 4 to the outer shell 4.

[0033] Furthermore, when the sealing member 6 is stacked on the rod guide 5, as shown in Figure 4, the outer seal 8 is pressed against the tapered surface t on the outer periphery of the small diameter portion 5c of the rod guide 5, and the tip side, which is the lower end of the outer seal 8, deforms so as to expand in diameter in accordance with the tapered surface t, so that the outer diameter of the tip of the first lip 8b becomes larger than the inner diameter of the outer shell 4 shown by the dashed line in Figure 4, and the outer diameter of the tip of the second lip 8c also becomes larger than the inner diameter of the outer shell 4.

[0034] Therefore, when the seal member 6 is placed on the rod guide 5 housed in the outer shell 4, the outer seal 8 comes into contact with the tapered surface t on the outer periphery of the rod guide 5, causing the lower end to expand and deform, and the first lip 8b and the second lip 8c are pressed against the inner circumferential surface of the outer shell 4. The outer periphery of the outer seal 8 other than the first lip 8b and second lip 8c also comes into close contact with the inner periphery of the outer shell 4 due to the expansion and deformation, but the contact surface pressure of the first lip 8b and the second lip 8c against the outer shell 4 is higher than the contact surface pressure of the outer periphery of the outer seal 8 other than the first lip 8b and second lip 8c.

[0035] Therefore, a gradient is generated in the contact surface pressure at the portion where the outer periphery of the outer seal 8 contacts the inner periphery of the outer shell 4, improving the sealing performance when the outer seal 8 seals the inner periphery of the outer shell 4. Note that the tapered surface t provided on the outer periphery of the rod guide 5 only needs to have a shape that can expand and deform the lower end of the outer seal 8 to press the first lip 8b against the inner periphery of the outer shell 4, so it may be an inclined surface that slopes at a constant gradient, a curved surface, or an inclined surface whose gradient changes midway.

[0036] Next, the valve case 12 is provided with a suction passage 21 that connects the reservoir R and the piston-side chamber R2, and a discharge passage 22 that similarly connects the reservoir R and the piston-side chamber R2. The suction passage 21 is provided with a check valve 23 that only allows liquid to flow from the reservoir R to the piston-side chamber R2, and the discharge passage 22 is provided with a damping valve 24 that only allows liquid to flow from the piston-side chamber R2 to the reservoir R and provides resistance to the flow of liquid passing through.

[0037] The hydraulic equipment is configured as described above, and its operation will be described next. When the twin-cylinder shock absorber, which is a hydraulic equipment, extends, the piston 2 moves upward in FIG. 1, increasing the pressure in the rod-side chamber R1 at the top of the figure, and the liquid in the rod-side chamber R1 moves to the piston-side chamber R2 via port 2b of the piston 2. The damping valve 14 installed in port 2b provides resistance to this liquid movement, creating a pressure difference between the rod-side chamber R1 and the piston-side chamber R2, causing the twin-cylinder shock absorber to generate an extension-side damping force that suppresses the extension operation. Furthermore, as the rod 3 retracts from the cylinder 1, the check valve 23 opens, and the liquid lacking in the cylinder 1 is supplied from the reservoir R to the cylinder 1 via the suction passage 21 of the valve case 12.

[0038] Conversely, when the twin-cylinder shock absorber contracts, the piston 2 moves downward in FIG. ,B As the rod 3 penetrates into the cylinder 1, the liquid in the cylinder 1 becomes excessive by the volume of the rod that penetrates into it.

[0039] In this case, the check valve 13 opens and the pressure in the rod side chamber R1 and the piston side chamber R2 become approximately equal, but the excess liquid is discharged to the reservoir R through the discharge passage 22, and the damping valve 24 provides resistance to the flow of liquid passing through this discharge passage 22, so that the pressure inside the cylinder 1 increases, and the twin-tube shock absorber generates a compression side damping force that suppresses the contraction operation in accordance with the pressure inside the cylinder 1 and the pressure-receiving area difference in the piston 2.

[0040] As described above, the hydraulic equipment of this embodiment comprises a cylindrical outer shell 4, a rod 3 inserted into the outer shell 4 so as to be axially movably, an annular rod guide 5 fitted onto the inner periphery of one end of the outer shell 4, through which the rod 3 is inserted and which has a tapered surface t on the atmospheric side of the outer periphery, an annular insert metal 7 laminated on the rod guide 5, and an annular outer periphery seal 8 provided on the outer periphery of the insert metal 7 and pressed against the tapered surface t to come into close contact with the inner periphery of the outer shell 4, and a seal member 6 inserted into the inner periphery of one end of the outer shell 4, the outer periphery seal 8 having an annular first lip 8b on its outer periphery which abuts against the inner periphery of the outer shell 4 when the outer periphery seal 8 abuts against the tapered surface t, and the first lip 8b does not abut against the inner periphery of the outer shell 4 when the outer periphery seal 8 is not abutting against the tapered surface t.

[0041] In hydraulic equipment configured in this manner, when the outer seal 8 is not in contact with the tapered surface t, the first lip 8b of the outer seal 8 does not contact the inner periphery of the outer shell 4. This means that the first lip 8b does not provide resistance when inserting the seal member 6 into the outer shell 4, making it easy to insert the seal member 6 into the outer shell 4 and preventing damage to the first lip 8b when inserting the outer seal 8 into the outer shell 4. Furthermore, in the hydraulic equipment of this embodiment, when the outer seal 8 comes into contact with the tapered surface t, it expands in diameter and presses the first lip 8b against the inner periphery of the outer shell 4, thereby increasing the contact surface pressure of the first lip 8b and improving sealing performance. As described above, the hydraulic equipment of this embodiment can achieve good sealing performance without compromising ease of assembly. Furthermore, in the process of manufacturing a twin-cylinder shock absorber, a work step of injecting gas into the reservoir R may be employed in which, with the sealing member 6 housed in the outer shell 4, the gas is injected into the reservoir R from between the outer seal 8 and the outer shell 4, but when the sealing member 6 is raised from the rod guide 5, the first lip 8b is not pressed strongly against the outer shell 4, making it easy to seal in the gas. Therefore, according to the hydraulic equipment of this embodiment, when the hydraulic equipment is a twin-cylinder shock absorber, not only is assembly and sealing performance improved, but the work of sealing in the gas is also made easier.

[0042] As in the outer seal 8 in the first modified example of the hydraulic equipment shown in Figure 5, the tips of the first lip 8b1 and the second lip 8c1 may be formed into arc-shaped surfaces. According to the hydraulic equipment in the first modified example of one embodiment configured in this manner, the seal member 6 can be inserted into the outer shell 4 with less resistance, further improving the ease of assembly.

[0043] Furthermore, the outer periphery seal 8 in the hydraulic device of this embodiment has multiple annular corners formed by forming a stepped cross section of the outer periphery of the end portion facing the inside of the outer shell 4 on the side opposite the atmosphere. A first lip 8b is formed at the annular corner closest to the atmosphere among the annular corners, and a second lip that fits tightly against the inner periphery of the outer shell 4 is formed at the annular corners other than the annular corner forming the first lip 8b. According to the hydraulic device configured in this manner, in addition to the first lip 8b, the hydraulic device is also provided with a second lip 8c that increases the contact surface pressure with the inner periphery of the outer shell 4, thereby further improving sealing performance. Furthermore, since the first lip 8b and the second lip 8c are formed at multiple annular corners formed by forming a stepped cross section of the outer periphery of the end portion facing the inside of the outer shell 4, the outer diameter of the second lip 8c is equal to or smaller than the largest outer diameter of the outer periphery seal 8 when the outer periphery seal 8 is not in contact with the tapered surface t of the rod guide 5. Therefore, with a hydraulic device configured in this manner, when the seal member 6 is inserted into the outer shell 4, no large frictional force is generated between the second lip 8c and the outer shell 4, thereby further improving sealing performance without impairing assembly. Furthermore, since the first lip 8b and the second lip 8c are formed by forming the outer periphery of the end of the outer seal 8 on the side opposite to the atmosphere, facing the inside of the outer shell 4, in a stepped cross section, the first lip 8b and the second lip 8c do not get caught in the mold when the seal member 6 is removed from the mold.

[0044] 6, the cross section of the outer periphery of the end of the outer periphery seal 81 facing away from the atmosphere may be formed into a multi-step staircase shape, thereby providing two or more second lips 81b, 81c in addition to the first lip 81a facing furthest away from the atmosphere. According to the hydraulic device of the second modified example of one embodiment configured in this manner, by providing a plurality of second lips 81b, 81c that come into contact with the inside of the outer shell 4 with a large contact surface pressure, it is possible to further improve sealing performance.

[0045] Furthermore, the shape may be modified as in rod guide 51 in hydraulic equipment of a third modified example of one embodiment shown in Fig. 7. Rod guide 51 includes a main body portion 51a, an annular small-diameter portion 51b having a small outer diameter at the atmosphere-side end of main body portion 51a, an outer peripheral inclined portion 51b1 whose outer diameter decreases toward the atmosphere side and forms a tapered surface t1 on the outer periphery, and an annular portion 51b2 that rises perpendicularly from outer peripheral inclined portion 51b1 and whose outer peripheral surface faces the inner periphery of outer shell 4. When rod guide 51 configured in this manner is fitted to the inner periphery of an open end that is one end of outer shell 4, an annular gap is formed between small-diameter portion 51b and outer shell 4, and outer peripheral seal 8 of sealing member 6 is housed in this annular gap.

[0046] When the outer periphery seal 8 abuts against the tapered surface t1 on the outer periphery of the outer periphery inclined portion 51b1, the lower end expands in diameter and the first lip 8b and the second lip 8c are pressed against the inner periphery of the outer shell 4, thereby increasing the contact surface pressure of the first lip 8b and the second lip 8c against the inner periphery of the outer shell 4 and improving sealing performance. The volume of the annular gap between the small diameter portion 51b and the outer shell 4 in the rod guide 51 of this embodiment is smaller than the volume of the annular gap between the small diameter portion 5c in the rod guide 5 and the outer shell 4 described above, and is therefore smaller than the volume of the outer periphery seal 8, because the rod guide 51 has the annular portion 51b2 compared to the small diameter portion 5c in the rod guide 5, the entire outer periphery of which is tapered surface t.

[0047] In the hydraulic device according to the third modification of an embodiment configured as described above, the filling rate, which is the ratio of the volume of the outer seal 8 to the volume of the annular gap, is higher than the filling rate, which is the ratio of the volume of the outer seal 8 to the volume of the annular gap, in the hydraulic device according to the first embodiment. Therefore, in the hydraulic device according to the third modification of an embodiment, the compression amount of the outer seal 8 increases, and although the gradient of the contact surface pressure of the second lip 8c relative to the inner circumference of the outer shell 4 decreases, the contact surface pressure on the outer circumference of the outer seal 8 increases overall, so that sealing performance is not impaired even if there is a small scratch on the outer circumference of the outer seal 8. Therefore, in the hydraulic device according to the third modification of an embodiment, sealing performance can be improved by the first lip 8b, and stable sealing performance can be obtained by increasing the filling rate of the outer seal 8 in the annular gap.

[0048] In the above description, the hydraulic equipment is a twin-tube shock absorber, but the present invention can also be applied to a single-tube shock absorber in which the piston slides directly inside the outer shell, or to hydraulic equipment other than shock absorbers, such as actuators.

[0049] Although the preferred embodiment of the present invention has been described in detail, modifications, variations and changes can be made thereto without departing from the scope of the appended claims. [Explanation of symbols]

[0050] 3 Rod, 4 Outer shell, 5, 51 Rod guide, 5c, 51b Small diameter portion, 6 Seal member, 7 Insert metal, 8 Peripheral seal, 8b First lip, 8c Second lip, 51b1 Peripheral inclined portion, 51b2 Annular portion, t, t1 Tapered surface

Claims

1. A cylindrical outer shell; a rod inserted into the outer shell so as to be axially movable; a rod guide having an annular shape, fitted onto an inner periphery of one end of the outer shell, through which the rod is inserted, and having a tapered surface on an outer periphery facing the atmosphere; a seal member that is inserted into the inner periphery of the one end of the outer shell, the seal member having an annular insert metal laminated on the rod guide and an annular outer periphery seal that is provided on the outer periphery of the insert metal and pressed against the tapered surface to be in close contact with the inner periphery of the outer shell, the outer periphery seal has an annular first lip formed at an annular corner closest to the atmosphere among a plurality of annular corners provided on the outer periphery, and a second lip formed at an annular corner other than the annular corner forming the first lip among the annular corners and in close contact with the inner periphery of the outer shell, The first lip abuts against the inner periphery of the outer shell when the outer periphery seal abuts against the tapered surface, and does not abut against the inner periphery of the outer shell when the outer periphery seal is not abutting against the tapered surface. A hydraulic device characterized by:

2. A cylindrical outer shell; a rod inserted into the outer shell so as to be axially movable; a rod guide having an annular shape, fitted onto an inner periphery of one end of the outer shell, through which the rod is inserted, and having a tapered surface on an outer periphery facing the atmosphere; a seal member that is inserted into the inner periphery of the one end of the outer shell, the seal member having an annular insert metal laminated on the rod guide and an annular outer periphery seal that is provided on the outer periphery of the insert metal and pressed against the tapered surface to be in close contact with the inner periphery of the outer shell, the outer circumferential seal has an annular first lip formed by a plurality of annular corners provided on an outer periphery at an end portion on the side opposite to the atmosphere that faces the inside of the outer shell and that have a stepped cross section, and the first lip is formed by the annular corner that is closest to the side opposite to the atmosphere, The first lip abuts against the inner periphery of the outer shell when the outer periphery seal abuts against the tapered surface, and does not abut against the inner periphery of the outer shell when the outer periphery seal is not abutting against the tapered surface. A hydraulic device characterized by:

3. the rod guide has an annular small diameter portion having a small outer diameter at an air side end, the small diameter portion has an outer peripheral inclined portion whose outer diameter becomes smaller toward the atmosphere side and forms the tapered surface on its outer periphery, and an annular portion that rises vertically from the outer peripheral inclined portion and whose outer peripheral surface faces the inner periphery of the outer shell, The outer circumferential seal is accommodated in an annular gap between the small diameter portion and the outer shell.

3. The hydraulic device according to claim 1 or 2.

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