Damper

Abstract

To secure sealability of a damper to which a lock ring fastening structure is applied.SOLUTION: An outer flange part 73 of a boss member 71 is disposed between a rock ring 41 and a rod guide 51 and a compression coil spring 93 is disposed between an inner flange part 74 of the boss member 71 and a washer 82 of an oil seal 81. In the structure, the oil seal 81 is pressed to a receiving surface 62 of the rod guide 51 by a biasing force of the spring 93. Thus, the structure can prevent sealability from being deteriorated by deformation of the washer 82 of the oil seal 81 caused by axial force of the lock ring 41 to secure the sealability of the oil seal 81.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a shock absorber to which a lock ring fastening structure is applied. [Background technology]

[0002] Patent Document 1 discloses a shock absorber (hereinafter referred to as a "conventional shock absorber") in which a cap 18 screwed onto the upper end of an outer tube 11 (base shell) is tightened to co-tighten a rod guide 15 and an oil seal 16 interposed between the upper end of a cylinder 12 and the cap 18, in other words, to apply axial force to the rod guide 15 and the oil seal 16. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-090606 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, for the purpose of overhaul, railway vehicle shock absorbers are configured to apply an axial force to the cylinder and the rod guide by applying a lock ring fastening structure that fastens a lock ring screwed onto the inner circumference of the opening of the base shell. In such railway vehicle shock absorbers, if a structure in which the rod guide and the oil seal are fastened together in a conventional shock absorber (hereinafter referred to as a "co-fastening structure") is applied, the core metal of the oil seal may deform, and the sealing performance of the oil seal may be reduced. An object of the present invention is to ensure the sealing performance of a shock absorber to which a lock ring fastening structure is applied. [Means for solving the problem]

[0005] The shock absorber of the present invention is characterized in that it has a second fixed member whose radially outer side is sandwiched between a blocking member and a first fixed member and whose radially inner side faces the other axial end side of the first sealing member and applies axial force to the first sealing member. Effect of the Invention

[0006] According to the present invention, it is possible to ensure the sealing performance of a shock absorber to which a lock ring fastening structure is applied. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a cross-sectional view of a cylinder body of the shock absorber according to the first embodiment. [Diagram 2] FIG. 2 is an enlarged view of a main part in FIG. [Diagram 3] FIG. 11 is an enlarged view of a main part in a second embodiment. [Figure 4] FIG. 13 is an explanatory view of a third embodiment, and is a plan view showing a part of a boss. [Diagram 5] FIG. 11 is an enlarged view of a main part in a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] A first embodiment of the present invention will now be described with reference to the accompanying drawings. In the first embodiment, a twin-tube horizontal bi-flow hydraulic shock absorber 1 (hereinafter referred to as "shock absorber 1") that is mounted sideways ("horizontally" in the first embodiment) between the body and bogie of a railway vehicle (not shown) will be described as an example. For convenience, the right side in Fig. 1 will be referred to as "one end side (one axial end side)", the left side in Fig. 1 will be referred to as "the other end side (the other axial end side)", the left-right direction in Fig. 1 will be referred to as "the axial direction of shock absorber 1", and the up-down direction in Fig. 1 will be referred to as "the up-down direction".

[0009] As shown in FIG. 1, the shock absorber 1 has a cylindrical base shell 3 (first cylinder), a cylinder 2 (second cylinder) concentrically disposed within the base shell 3, and an annular reservoir chamber 4 formed between the cylinder 2 and the base shell 3. The shock absorber 1 has a base cap 27 fixed to an end 5 on one end side of the base shell 3. The base cap 27 is formed in a cylindrical shape with a bottom, and a cylindrical portion 28 is fitted into a cap fitting portion 7 formed on the inner circumference of the end 5 on one end side of the base shell 3. The end 5 on one end side of the base shell 3 and a bottom 32 of the base cap 27 are joined by full circumference welding. An attachment member 23 to be connected to the vehicle body side is joined to one end side of the bottom 29 of the base cap 27.

[0010] The shock absorber 1 has a piston 9 slidably inserted in a cylinder 2. The piston 9 divides the inside of the cylinder 2 into a first chamber 2A at the other end side and a second chamber 2B at one end side. The piston 9 has an extension-side relief valve 16 that opens when the hydraulic pressure in the first chamber 2A reaches a set pressure during the extension stroke of the piston rod 10, and releases the pressure (hydraulic fluid) of the first chamber 2A to the second chamber 2B. The piston 9 has an extension-side orifice passage 18 that generates a damping force with orifice characteristics during the extension stroke of the piston rod 10. The piston 9 has a compression-side relief valve 17 that opens when the hydraulic pressure in the second chamber 2B reaches a set pressure during the compression stroke of the piston rod 10, and releases the pressure (hydraulic fluid) of the second chamber 2B to the first chamber 2A. The piston 9 has a compression-side orifice passage 19 that generates a damping force with orifice characteristics during the compression stroke of the piston rod 10.

[0011] The shock absorber 1 has a piston rod 10 with one end 11 connected to a piston 9. The other end 12 of the piston rod 10 is inserted into a rod guide 51 (closure member) attached to the other end of the cylinder 2 and the base shell 3, and extends to the outside of the cylinder 2. An attachment member 22 connected to the bogie side is joined to the end 12 of the piston rod 10. A cylindrical cover 8 (partially shown in FIG. 1) is attached to the end 12 of the piston rod 10 to cover the piston rod 10 protruding from the cylinder body 25 to the outside.

[0012] The shock absorber 1 has a base valve 31 that controls the flow of hydraulic fluid between the second chamber 2B and the reservoir chamber 4. The base valve 31 has a valve body 32 that divides the second chamber 2B from the reservoir chamber 4 and forms the third chamber 21 between the base valve 31 and the base cap 27. The valve body 32 has passages 33 and 34 that communicate the second chamber 2B and the third chamber 21. The passage 33 is provided with a check valve 35 that allows the hydraulic fluid to flow from the third chamber 21 to the second chamber 2B. The passage 34 is provided with a relief valve 36 that opens when the hydraulic pressure in the second chamber 2B reaches a set pressure and releases the pressure (hydraulic fluid) of the second chamber 2B to the reservoir chamber 4 via the third chamber 21. Note that, as the hydraulic fluid, hydraulic fluid is sealed in the cylinder 2, and hydraulic fluid and gas are sealed in the reservoir chamber 4.

[0013] An end face 37 on one end side of the valve body 32 abuts against the bottom 29 of the base cap 27. The valve body 32 has a groove 38 extending radially from the end face 37 (the "up-down direction" in FIG. 1). The groove 38 forms a flow passage 39 with a rectangular cross section between the valve body 32 and the bottom 29 of the base cap 27, which connects the third chamber 21 to the reservoir chamber 4. The flow passage 39 is located at a position lower than the liquid level of the hydraulic fluid sealed in the reservoir chamber 4 when the shock absorber 1 is attached sideways.

[0014] In the shock absorber 1 described above, during the extension stroke of the piston rod 10, the hydraulic fluid of a volume that the piston rod 10 has withdrawn from the cylinder 2 flows from the reservoir chamber 4 to the second chamber 2B via the groove 38 (flow path 39) formed in the valve body 32, the third chamber 21, the passage 33 formed in the valve body 32, and the check valve 35. On the other hand, during the contraction stroke of the piston rod 10, the hydraulic fluid of a volume that the piston rod 10 has advanced into the cylinder 2 flows from the second chamber 2B to the reservoir chamber 4 via the passage 34 formed in the valve body 32, the relief valve 36, the third chamber 21, and the groove 38 (flow path 39) formed in the valve body 32.

[0015] Next, the structure of the other end 26 of the cylinder body 25 will be described. 1 or 2, the base shell 3 has an internal thread portion 13 formed in an end portion 6 on the other end side. An external thread portion 42 formed in a lock ring 41 (first fixing member) is screwed into the internal thread portion 13. An end face 43 on the other end side of the lock ring 41 is formed with a plurality of tool fitting holes 44 (four in the first embodiment) into which a tool (not shown) is fitted when the lock ring 41 is tightened.

[0016] As shown in FIG. 1, the rod guide 51 has an end 52 on one end side that is fitted to the inner periphery of the end 14 on the other end side of the cylinder 2. The end 52 closes the end 14 on the other end side of the cylinder 2. The rod guide 51 has a flange portion 54 that is fitted to an inner cylindrical surface 15 formed on the end 6 on the other end side of the base shell 3. An end face 55 on one end side of the flange portion 54 is abutted against an end face (reference numeral omitted) on the other end side of the cylinder 2. A bush 47 that slidably guides the piston rod 10 is press-fitted into one end side of the rod guide 51. An annular seal groove 49 for accommodating an O-ring 48 that is in sliding contact with the piston rod 10 is formed on the other end side of the bush 47 of the rod guide 51.

[0017] 1 or 2, the rod guide 51 has an end portion 53 on the other end side that is fitted into the inner periphery of a cylindrical portion 72 of a boss member 71 (second fixed member). The boss member 71 is formed into a hat shape by press molding (cylindrical drawing molding). The boss member 71 has an outer flange portion 73 formed on the periphery of the opening on one end side of the cylindrical portion 72, and an inner flange portion 74 formed on the periphery of the opening on the other end side of the cylindrical portion 72.

[0018] The outer flange portion 73 is in sliding contact with the inner cylindrical surface 15 formed on the end portion 6 on the other end side of the base shell 3. A notch 57 is formed on the periphery on the other end side of the flange portion 54 of the rod guide 51. An O-ring 60 (second seal member) that seals between the rod guide 51, the boss member 71, and the cylinder 2 is accommodated in an annular triangular groove 59 that is surrounded by the notch 57 of the flange portion 54, the outer flange portion 73 of the boss member 71, and the cylinder 2 and has a triangular cross section (right-angled isosceles triangle) taken along the axial plane.

[0019] By fastening the lock ring 41, the outer flange portion 73 is sandwiched between the lock ring 41 and the flange portion 54 of the rod guide 51. The axial force generated by fastening the lock ring 41 acts on the outer flange portion 73 of the boss member 71, the flange portion 54 of the rod guide 51, and the cylinder 2. An end face (reference number omitted) on one end side of the cylinder 2 is supported by the valve body 32 and the base cap 27.

[0020] The shock absorber 1 has a rotation prevention mechanism that prevents the boss member 71 from rotating relative to the rod guide 51 due to the frictional force acting between the members when the lock ring 41 is fastened. The rotation prevention mechanism has a protrusion 76 formed on an end face 75 on one end side of the outer flange portion 73 of the boss member 71, and a recess 67 formed on an end face 55 on one end side of the flange portion 54 of the rod guide 51, into which the protrusion 76 fits.

[0021] An oil seal 81 is disposed at the end 53 on the other end side of the rod guide 51. The oil seal 81 has a washer 82, one end side of an outer circumferential surface 83 (outer circumferential portion) of which is slidably fitted into a seal assembly hole 61 formed in an end face 58 on the other end side of the rod guide 51. The oil seal 81 has an annular seal portion 85 which is vulcanization bonded to the washer 82. The seal portion 85 has inner circumferential side lip portions 86, 87 which are in sliding contact with the piston rod 10, a seat portion 88 which covers the end face on one end side of the washer 82, and an outer circumferential side lip portion 89 which is formed on the outer periphery of the seat portion 88 and protrudes towards the one end side.

[0022] Lip portions 86, 87 on the inner peripheral side of the seal portion 85 are pressed against the piston rod 10 by ring-shaped seal springs 90, 91. An annular seat portion 88 formed on the seal portion 85 abuts against an annular receiving surface 62 formed on the bottom surface of the seal assembly hole 61 of the rod guide 51. A lip portion 89 on the outer peripheral side of the seal portion 85 is inserted (filled) into an annular seal groove 63 formed on the outer periphery of the bottom surface of the seal assembly hole 61 of the rod guide 51, in other words, into the seal groove 63 formed on the outer periphery of the receiving surface 62.

[0023] The seal portion 85 is formed such that the inner peripheral lip portions 86 and 87, the outer peripheral lip portion 89, and the seat portion 88 are continuous and not separated. An annular recess 64 is formed on the inner periphery of the receiving surface 62 of the rod guide 51 to accommodate the lip portion 86 on one end side. An annular chamber 65 is formed between the annular recess 64 and the seal portion 85 (lip portion 86 and seat portion 88). The chamber 65 is connected to the reservoir chamber 4 by a passage 66.

[0024] In the first embodiment, the shock absorber 1 has a plurality of compression coil springs 93 (hereinafter referred to as "springs 93") (only two are shown in FIG. 1) that urge the oil seal 81 (first seal member) toward one end in the axial direction, in other words, that press the oil seal 81 against the rod guide 51 (blocking member). The springs 93 (elastic members) have their other end fixed to the inner flange portion 74 of the boss member 71, and their one end abutted against an end face 84 on the other end side of the washer 82 that faces the inner flange portion 74.

[0025] The spring force generated by compressing the spring 93 (hereinafter referred to as "the biasing force of the spring 93") is received by the annular receiving surface 62 formed on the other end side of the rod guide 51, via the washer 82 of the oil seal 81 and the seat portion 88 of the seal portion 85. In the first embodiment, the biasing force of the spring 93 is set to be smaller than the axial force generated by tightening the lock ring 41 (hereinafter referred to as "the axial force of the lock ring 41").

[0026] Here, in the co-tightening structure of conventional shock absorbers, the axial force generated by tightening the lock ring acts on the washer of the oil seal, which may cause the washer to deform and reduce the sealing performance of the oil seal.

[0027] In contrast, in the first embodiment, an outer flange portion 73 formed on one end side of a boss member 71 (second fixed member) is interposed between the lock ring 41 (first fixed member) and the rod guide 51 (blocking member), and a compression coil spring 93 (elastic member) is interposed between an inner flange portion 74 formed on the other end side of the boss member 71 and a washer 82 of an oil seal 81 (first sealing member). In the first embodiment, the oil seal 81 is pressed against the receiving surface 62 of the rod guide 51 by the biasing force of the spring 93. In other words, the axial force acting on the oil seal 81 is the biasing force of the spring 93 only. According to the first embodiment, the washer 82 of the oil seal 81 is not deformed by the axial force of the lock ring 41, so it is possible to avoid a decrease in the sealing performance of the oil seal 81 due to deformation of the washer 82, and the sealing performance of the oil seal 81 can be ensured. In the first embodiment, the repulsive force of the spring 93 is determined by managing the mounting length, spring constant, etc., so that the axial force acting on the washer 82 of the oil seal 81 can be adjusted independently of the axial force of the lock ring 41. In the first embodiment, the convex portion 76 formed on the boss member 71 is fitted into the concave portion 67 formed on the rod guide 51, so that the boss member 71 can be prevented from rotating relative to the rod guide 51 due to the frictional force acting between the members when the lock ring 41 is fastened. This makes it possible to prevent the O-ring 60 (second seal member) that seals between the rod guide 51, the boss member 71, and the cylinder 2 from being dragged within the triangular groove 59 and being damaged.

[0028] Second embodiment Next, a second embodiment will be described with reference to FIG. In addition, the same names and symbols are used for the parts common to the first embodiment, and duplicated explanations will be omitted.

[0029] In the first embodiment, a compression coil spring 93 (elastic member) is interposed between the inner flange portion 74 of the boss member 71 (second fixed member) and the washer 82 of the oil seal 81 (first sealing member), and the oil seal 81 (first sealing member) is pressed against the receiving surface 62 of the rod guide 51 by the biasing force of the spring 93.

[0030] In contrast, in the second embodiment, an annular elastic member 95 having a triangular cross section taken along an axial plane is formed on an end face 77 on one end side of the inner flange portion 74 of the boss member 71, and the elastic member 95 is compressed between the inner flange portion 74 of the boss member 71 and the washer 82 of the oil seal 81, so that the oil seal 81 is pressed against the receiving surface 62 of the rod guide 51 by the elastic force (repulsion force) of the elastic member 95. In the second embodiment, the elastic member 95 is made of, for example, nitrile rubber, and is vulcanization bonded to the end face 77 on one end side of the inner flange portion 74 of the boss member 71. In the second embodiment, it is possible to obtain the same effects as those of the first embodiment described above.

[0031] Third embodiment Next, a third embodiment will be described with reference to FIGS. In addition, the same names and symbols are used for the parts common to the first embodiment, and duplicated explanations will be omitted.

[0032] In the above-described embodiment, an elastic member (compression coil spring 93, elastic member 95) is interposed between the inner flange portion 74 of the boss member 71 (second fixed member) and the washer 82 of the oil seal 81 (first sealing member), and the oil seal 81 is pressed against the receiving surface 62 of the rod guide 51 (blocking member) by the repulsive force (biasing force) of the elastic member.

[0033] In contrast to this, in the third embodiment, a cut-out mold (not shown) is used to form a plurality of (three in the third embodiment, only two shown in FIG. 4) cut-out portions 97 (protrusions) on the inner flange portion 74 of the boss member 71, and the cut-out portions 97 are configured to press the oil seal 81 (first seal member) against the receiving surface 62 of the rod guide 51. The cut-out portions 97 are formed so that their cross section taken along the axial plane is V-shaped. The multiple cut-out portions 97 extend in an arc shape along a circle concentric with the cylindrical portion 72, and are equally spaced about the center line of the cylindrical portion 72. The central angle of the arc is, for example, 60 degrees.

[0034] In the third embodiment, it is possible to obtain the same effects as those in the first embodiment described above. Furthermore, in the third embodiment, the repulsive force (pressing force) of the cut-and-raised portion 97 is determined by managing the cut-and-raised width, cut-and-raised height, etc. of the cut-and-raised portion 97, so that the axial force acting on the washer 82 of the oil seal 81 can be adjusted independently of the axial force of the lock ring 41.

[0035] The above-described embodiment can be configured as follows. In the embodiment described above, the outer circumferential surface 83 (outer circumferential portion) of the washer 82 of the oil seal 81 (first seal member) is configured to slidably fit into the seal assembly hole 61 of the rod guide 51 (closing member). In this case, during the manufacturing process, when the boss member 71 (second fixed member) is assembled to the other end 26 of the cylinder body 25, the washer 82 of the oil seal 81 is covered by the boss member 71, making it difficult to visually align the washer 82 radially with respect to the seal assembly hole 61 of the rod guide 51. Therefore, in a step prior to assembling the boss member 71 (second fixed member) to the other end 26 of the cylinder body 25, the washer 82 of the oil seal 81 is press-fitted into the seal assembly hole 61 of the rod guide 51 and temporarily fixed therein. As a result, when assembling the boss member 71 (second fixed member) to the end portion 26 on the other end side of the cylinder body 25 during the manufacturing process, it is not necessary to radially align the washer 82 of the oil seal 81 with the seal assembly hole 61 of the rod guide 51, thereby improving ease of assembly. [Explanation of symbols]

[0036] 1 shock absorber, 2 cylinder (second cylinder), 2A first chamber, 2B second chamber, 3 base shell (first cylinder bottom), 6 end portion on other end side, 10 piston rod, 11 end portion on one end side, 12 end portion on the other end side, 41 lock ring (first fixed member), 51 rod guide (blocking member), 71 boss member (second fixed member), 81 oil seal (first seal member)

Claims

1. A cylindrical first cylinder; A cylindrical second cylinder disposed within the first cylinder; A piston inserted into the second cylinder; a piston rod having an axial end connected to the piston and an axial end extending to the outside of the second cylinder; a blocking member that blocks the other axial end of each of the first cylinder and the second cylinder; a first fixing member that is screwed to an inner periphery of an end portion on the other end side of the first cylinder and applies an axial force to the second cylinder and the closing member; a first seal member having an axial end side that abuts against the blocking member and a radial inner circumferential side that abuts against the piston rod; a second fixed member whose radially outer peripheral side is sandwiched between the blocking member and the first fixed member and whose radially inner peripheral side faces the other axial end side of the first seal member, and which applies axial force to the first seal member.

2. 2. The shock absorber according to claim 1, A shock absorber, wherein an axial force applied to the first seal member is smaller than an axial force applied to the closing member.

3. 3. The shock absorber according to claim 1 or 2, A shock absorber, characterized in that the second fixed member has a protrusion formed on a radially inner side thereof and pressing the first seal member against the first fixed member.

4. 3. The shock absorber according to claim 1 or 2, a shock absorber comprising an elastic member interposed between the closing member and the first seal member;

5. 3. The shock absorber according to claim 1 or 2, A shock absorber characterized by having a second seal member that abuts against the second cylinder, the blocking member, and the second fixed member, a convex portion formed on one of the blocking member and the second fixed member, and a concave portion formed on the other of the blocking member and the second fixed member, into which the convex portion is fitted.

6. 3. The shock absorber according to claim 1 or 2, The blocking member has an end face on the other axial end side thereof, the end face having a seal assembly hole into which an outer periphery of the first seal member is press-fitted.

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