shock absorbers

Abstract

Shock absorber, comprising: a cylinder (10) in which an operating fluid is enclosed; a piston (11) slidably inserted into the cylinder (10) to divide the interior of the cylinder (10) into two chambers; a piston rod (16) connected to the piston (11), the piston rod (16) having at least one end extending from the cylinder (10); a valve main body (14) having a passage (26) through which the operating fluid flows due to a sliding movement of the piston (11); a fixed shaft (21) inserted through a valve main body insertion hole (23) formed through the valve main body (14); an inner seat (31) having a ring shape provided around the valve main body insertion hole (23) to extend from the valve main body insertion hole (23); an outer seat (32) having a ring shape provided on an outer peripheral side of the inner seat (31) to extend from the outer peripheral side of the inner seat (31) and to enclose an opening of the conduit (26); a disc valve (53, 54, 55, 56, 57, 58) having an annular shape capable of coming into contact with and separating from the inner seat (31) and the outer seat (32), the disc valve (53, 54, 55, 56, 57, 58) allowing the fixed stem (21) to pass through the disc valve (53, 54, 55, 56, 57, 58); a spring force applying means (84) for applying a force in a valve closing direction to the disc valve (53, 54, 55, 56, 57, 58) while allowing the fixed stem (21) to be inserted through the spring force applying means (84); and a cylindrical member (47) through which the fixed shaft (21) is inserted, the cylindrical member (47) being inserted into the disc valve (53, 54, 55, 56, 57, 58) and the spring force applying device (84), wherein: a radially extending gap is defined between the cylindrical element (47) and an inner side of the inner seat (31), wherein the shock absorber further comprises a flange portion (49) formed on an outer periphery of the cylindrical member (47) on a side close to the valve main body (14), wherein the disc valve has a plurality of valve discs (53, 54, 55, 56, 57, 58), wherein a largest diameter portion of the flange portion (49) has a larger diameter than that of a smallest diameter portion of an inner circumference of one (53) of the valve discs (53, 54, 55, 56, 57, 58), and wherein a largest diameter portion of the flange portion (49) has a larger diameter than that of a smallest diameter portion of an inner periphery of one (53) of the plurality of valve discs (53, 54, 55, 56, 57, 58) disposed closest to the valve main body (14).

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a shock absorber.

[0002] There exists a shock absorber comprising a disc valve that opens and closes a conduit through which an operating fluid flows by means of the movement of a piston. In the above-mentioned shock absorber, the disc valve is preloaded by a spring device (see, for example, JP S57-137735 A). SUMMARY OF THE INVENTION

[0003] In the shock absorber described above, the assembly (insertion / fixing) of a component for biasing the disc valve in a valve closing direction is complicated.

[0004] In view of the above-mentioned problem, it is an object of the present invention to provide a shock absorber which simplifies an assembly process.

[0005] In order to achieve the above-mentioned object, the present invention has a structure comprising: a spring force applying means for applying a force in a valve closing direction to the disc valve while allowing the fixed stem to be inserted through the spring force applying means; and a cylindrical member for allowing the fixed stem to be inserted through the cylindrical member, the cylindrical member being inserted into both the disc valve and the spring force applying means, wherein: the cylindrical member is provided to have a radially extending gap on an inner side of the inner seat of the valve main body. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] In the attached drawings: Fig. 1 is a sectional view showing a main portion of a shock absorber according to an embodiment of the present invention; Fig. 2 is a side view showing a cylindrical member of the shock absorber according to the embodiment of the present invention; Fig. 3 is a plan view showing one of the valve discs of the damper according to the embodiment of the present invention; Fig. 4 is a partially enlarged view showing the cylindrical member and the disc valves of the shock absorber according to the embodiment of the present invention, which are shown partially in cross section; Fig. 5 is a sectional view showing a state of the shock absorber according to the embodiment of the present invention at the time of attachment / insertion; and Fig. 6 is another sectional view showing a state of the shock absorber according to the embodiment of the present invention at the time of attachment / insertion. DETAILED DESCRIPTION OF THE INVENTION

[0007] An embodiment of the present invention will be described below with reference to the accompanying drawings.

[0008] A shock absorber of this design is a so-called hydraulic monotube shock absorber, as in Fig. 1. The shock absorber comprises a cylinder 10 having an approximately cylindrical shape in which an oil fluid, corresponding to an operating fluid, is enclosed. A piston 11 is slidably inserted into the cylinder 10. The interior of the cylinder 10 is divided by the piston 11 into two chambers, i.e., an upper chamber 12 and a lower chamber 13.

[0009] The piston 11 includes a piston main body (valve main body) 14 having an approximately disc-like shape and an annular sliding member 15. The sliding member 15 is arranged on an outer peripheral surface of the piston main body 14. The piston main body 14 is connected to one end of a piston rod 16. The other end of the piston rod 16 extends from the cylinder 10 (not shown).

[0010] The piston rod 16 includes a main shaft portion 20, an inserted shaft portion (fixed shaft) 21, and a threaded shaft portion 22. The inserted shaft portion 21 has a smaller diameter than that of the main shaft 20 and is provided at one end of the main shaft portion 20 on the side where the piston 11 is attached. The threaded shaft portion 22 is provided on the side of the inserted shaft portion 21 opposite to the side where the main shaft portion 20 is provided.

[0011] At the center of the piston main body 14, an insertion hole (valve main body insertion hole) 23, through which the inserted shaft portion 21 of the piston rod 16 is to be inserted, is formed to extend axially through the piston main body 14. A concave housing portion 24 having a larger inner diameter than the diameter of the insertion hole 23 and concave axially toward an intermediate position is formed at one axial end of the piston main body 14. The concave housing portion 24 is formed on the inner side of an annular wall portion 25 extending coaxially with the insertion hole 23. Inserting the inserted shaft portion 21 into the through hole 23 positions the piston main body 14 radially with respect to the piston rod 16.

[0012] A plurality of passages 26 (hereinafter, the passage is referred to as “passage”, “inner passage” or “extension side passage”) are formed through the piston main body 14 on the radially outer side of the insertion hole 23 within the concave housing portion 24. In Fig. 1, only one of them is shown due to cross-sectional limitations. The inner passage 26 connects the upper chamber 12 and the lower chamber 13 to allow the oil fluid to flow from the upper chamber 12 to the lower chamber 13 during the sliding movement of the piston 11 toward the upper chamber, i.e., during an extension stroke. Furthermore, a plurality of passages 27 (hereinafter, the passage is referred to as a "passage," "outer passage," or "displacement side passage") are formed through the piston main body 14 on the radially outer side of the inner passage 26 within the concave housing portion 24. In Fig. Due to cross-sectional limitations, only one of these is shown in Figure 1. The outer conduit 27 connects the upper chamber 12 and the lower chamber 13 to allow oil fluid to flow from the lower chamber 13 toward the upper chamber 12 during the sliding movement of the piston 11 toward the lower chamber 13, i.e., during a displacement stroke.

[0013] A damping force generating mechanism 28 for generating a damping force is provided on the inner conduits 26. The damping force generating mechanism 28 is provided on the side of the piston 11 closest to the lower chamber 13 in the axial direction. The inner conduits 26 form extension-side conduits through which oil fluid flows when the piston 11 moves toward the extension side, toward which the piston rod 16 extends outward from the cylinder 11. The damping force generating mechanism 28, provided on the extension-side conduits 26, includes an extension-side damping force generating mechanism that controls the flow of oil fluid through the displacement-side conduits 26 to generate the damping force.

[0014] A damping force generating mechanism 29 for generating a damping force is provided on the outer conduits 27. The damping force generating mechanism 29 is provided on the side of the piston 11 closest to the upper chamber 12 in the axial direction. The outer conduit 27 includes displacement-side conduits through which oil fluid flows when the piston 11 moves toward the displacement side where the piston rod 16 moves into the cylinder 10. The damping force generating mechanism 29, provided on the displacement-side conduits 27, includes a displacement-side damping force generating mechanism that controls the flow of oil fluid through the displacement-side conduits 27 to generate the damping force.

[0015] An inner seat 31, which forms the above-mentioned damping force generating mechanism 28, is formed on the concave housing portion 24 of the piston main body 14. The inner seat 31 is provided on the radially inner side of open ends of the extension-side conduits 26, the open ends being located on the lower chamber side 13. The inner seat 31 is formed to protrude in the axial direction of the piston main body 14. The inner seat 31 is formed to have an annular shape around the insertion hole 23, more specifically, to have an annular shape with the insertion hole 23 as a center. The inner seat 31 extends in the axial direction of the piston main body 14 to occupy a predetermined height over the entire circumference.

[0016] Further, an outer seat 32, which forms the above-mentioned damping force mechanism 28, is also formed on the concave housing portion 24 of the piston main body 14. The outer seat 32 is provided on the radially outer side of the open ends of the extension-side conduits 26, the open ends being located on the lower chamber side 13. The outer seat 32 is formed to extend in the axial direction of the piston main body 14. The outer seat 32 has a larger diameter than that of the inner seat 31 and is formed to have an annular shape on the outer peripheral side of the inner seat 31 so as to surround all the openings of the plurality of conduits 26 on the extension side. Specifically, the outer seat 32 is formed to assume an annular shape with the insertion hole 23 as a center.It should be noted that the outer seat 32 may also have an annular shape other than the annular shape, for example, a petal-like pattern having a large diameter portion and a small diameter portion arranged alternately, an elliptical shape, or the like.

[0017] The outer seat 32 extends in the axial direction of the piston main body 14 to occupy a predetermined height over the entire circumference. The outer seat 32 has a greater height in the axial direction toward the lower chamber 13 than that of the inner seat 31. The axial projections of the inner seat 31 and the outer seat 32 form an annular concave portion 33 having an annular shape concave in the axial direction of the piston main body 14 between the inner seat 31 and the outer seat 32. In addition, an annular concave portion 34 having an annular shape concave in the axial direction of the piston main body 14 is formed between the outer seat 32 and the annular wall portion 25.The open ends of the extension side pipes 26 at the lower chamber 13 are open at a bottom surface of the ring-like concave portion 33 formed at the inner side, whereas the open ends of the displacement side pipes 27 at the lower chamber 13 side are open at a bottom surface of the ring-like concave portion 34 arranged at the outer side.

[0018] A concave abutment portion 35, which is concave in the axial direction of the piston main body 14, is formed on the concave housing portion 24 of the piston main body 14. This concave abutment portion 35 is located on the radially outer side of the insertion hole 23 and on the radially inner side of the inner seat 31, that is, on the side of the inner seat 31 radially close to the insertion hole 23. The concave abutment portion 35 is formed on the inner side of the inner seat 31 to have an annular shape, specifically, an annular shape having the insertion hole 23 as a center.The annular concave portion 33 is concave toward the upper chamber side 12 to have a greater depth than that of the annular concave portion 34 in the axial direction of the piston main body 14, and the abutment concave portion 35 is concave toward the upper chamber side 12 to have a further greater depth than that of the annular concave portion 33 in the axial direction of the piston main body 14.

[0019] A mounting seat 40 is formed at one end of the piston main body 14 located on the upper chamber side 12. The mounting seat 40 is formed to extend in the axial direction of the piston main body 14 on the radially outer side of the insertion hole 23. The mounting seat 40 is formed to have an annular shape with the insertion hole 23 as the center and extends in the axial direction of the piston main body 14 to occupy a predetermined height over the entire circumference.

[0020] An inner seat 41, which forms the above-mentioned damping force generating mechanism 29, is formed at the end of the piston main body 14 located at the upper chamber 12 side. The inner seat 41 is formed on the radially outer side of the attachment seat 40 and the radially inner side of the open ends of the compression side passages 27, the open ends being close to the upper chamber 12, to extend in the axial direction of the piston main body 14. The inner seat 41 has a larger diameter than that of the attachment seat 40 and is formed to assume an annular shape around the insertion hole 23, specifically, an annular shape with the insertion hole 23 as a center. The inner seat 41 extends in the axial direction of the piston main body 14 to assume a predetermined height over the entire circumference.

[0021] Further, an outer seat 42, which forms the above-mentioned damping force generating mechanism 29, is formed at the end of the piston main body 14 located on the upper chamber 12 side. The outer seat 42 is formed on the radially outer side of the open ends of the compression side passages 27, the open ends being located close to the upper chamber 12, so as to extend in the axial direction of the piston main body 14. The outer seat 42 has a larger diameter than that of the inner seat 41 and is formed to assume an annular shape on the outer peripheral side of the inner seat 41 to enclose all the openings of the plurality of compression side passages 27, specifically, an annular shape with the insertion hole 23 as a center.It should be noted that the outer seat 42 may have an annular shape other than the annular or circular shape, for example, a petal-like shape having a larger diameter portion and a smaller diameter portion arranged alternately, an elliptical shape, or the like.

[0022] In the axial direction of the piston main body 14, the mounting seat 40, the inner seat 41, and the outer seat 42 extend to the same level. The projections of the mounting seat 40, the inner seat 41, and the outer seat 42 form an annular concave portion 43 and an annular concave portion 44 in the axial direction of the piston main body 14. The annular concave portion 43 has an annular shape that is concave in the axial direction of the piston main body 14 toward the lower chamber 13 and is formed between the mounting seat 42 and the inner seat 41, whereas the annular concave portion 44 has an annular shape that is concave in the axial direction of the piston main body 14 toward the lower chamber 13 and is formed between the inner seat and the outer seat 42.The open ends of the extension-side passages 26 on the upper chamber 12 side are open at a bottom surface of the inner annular concave portion 43, whereas the open ends of the displacement-side passages 27 on the upper chamber 12 side are open at a bottom surface of the outer annular concave portion 44. Note that a plurality of passage grooves (not shown) concave in the axial direction of the piston main body 14 toward the lower chamber 13 are formed on the outer seat 42 to radially extend therethrough. The outer seat 42 extends in the axial direction of the piston main body 14 toward the upper chamber 12 to occupy a predetermined height except for the passage grooves.

[0023] A cylindrical member 47 is formed on the lower chamber side 13 of the piston main body 14 to allow the inserted shaft portion 21 of the piston rod 16 to be inserted therethrough. Inserting the inserted shaft portion 21 through the cylindrical member 47 positions the cylindrical member 47 radially with respect to the piston rod 16. Radial concave engagement grooves 48 are formed on an outer peripheral portion of the cylindrical member 47 at two circumferential ends of the cylindrical member 47 in the axial direction, so that each of the engagement grooves 48 is formed in an annular shape coaxial with the cylindrical member 47. As a result, an annular flange portion 49 projecting radially outward is provided on the cylindrical member 47 to be formed on the axially outer side of each of the engagement grooves 48 formed at the two circumferential ends of the cylindrical member 47.Between the two engagement grooves 48, an annular sliding guide portion (large diameter portion) 50 having a larger diameter than that of each of the engagement grooves 48 is formed. Cylindrical outer peripheral surfaces of the two flange portions 49 and the sliding guide portion 50 have the same diameter. In addition, the two engagement grooves 48 have the same diameter. The flange portions 49 may be formed intermittently in the circumferential direction instead of being formed in the annular shape continuously in the circumferential direction.

[0024] As in Fig. 2, each of the engagement grooves 48 includes a groove bottom surface 48a, an inclined surface 48b, and a curved surface 48c. The groove bottom surface 48a has a cylindrical surface shape. The inclined surface 48b is formed on the side of the groove bottom surface 48a that is close to the sliding guide portion 50 and connects the groove bottom surface 48a and an outer peripheral surface of the sliding guide portion 50 to each other. The curved surface 48c is formed on the side of the groove bottom surface 48a that is opposite to the side on which the sliding guide portion 50 is formed and connects the groove bottom surface 48a and the outer peripheral surface of one of the flange portions 49 adjacent thereto. The inclined surface 48b on the sliding guide portion 50 side is slightly inclined.

[0025] As in Fig. 1, each of the flange portions 49 has a smaller diameter than an inner diameter of an inner peripheral surface of the abutment concave portion 35 of the piston main body 14. Therefore, the cylindrical member 47 moves into the abutment concave portion 35 of the piston main body 14 to abut against the bottom surface of the abutment concave portion 35. Specifically, the cylindrical member 47 is provided with a radially extending gap on the inner side of the inner seat 31, which forms the peripheral wall surface of the abutment concave portion 35 of the piston main body 14. The cylindrical member 47 and the piston main body 14 are radially positioned by the inserted shaft portion 21. As a result, the gap between the cylindrical member 47 and the peripheral wall surface of the abutment concave portion 35 is continuous over the entire circumference of the cylindrical member 47.In other words, the cylindrical member 47 has a clearance to allow free movement of the cylindrical member 47 in the radial direction with respect to the abutment concave portion 35. Forming one of the engaging grooves 48 and one of the flange portions 49 on the outer periphery of the cylindrical member 47 on the piston main body 14 side corresponding to one side in the axial direction is sufficient. However, in this embodiment, another pair of the engaging portion 48 and the flange portion 49 (second flange portion) is formed on the cylindrical member 47 on the opposite side in the axial direction to prevent alignment limitation at the time of insertion / fixing, thereby improving operability during insertion / fixing.

[0026] An axial length of each of the flange portions 49 is less than an axial depth of the concave abutment portion 35. Therefore, the curved portion 48c of each of the engagement grooves 48 formed in Fig. 2, closer to the piston main body 14 in the axial direction than the inner seat 31 shown in Fig. 1. Specifically, the groove bottom surface 48a of the upper engaging grooves 48 shown in Fig. 1 are axially aligned with a distal end surface of the inner seat 31. Further, a distal end surface of the outer seat 32 is axially aligned with respect to the groove bottom surface 48a of the upper one of the engagement grooves 48 shown in Fig. 1 are aligned.

[0027] The damping force generating mechanism 28 includes a disc valve that can simultaneously seat the inner seat 31 and the outer seat 32. The disc valve in this embodiment includes a plurality of valve discs 53 to 58, each having an annular shape. The damping force generating mechanism 28 further includes an annular spacer 60 and an annular movable spring locking member 61, a spring 62, and a fixed spring locking member 63. The annular spacer 60 is provided on the side of the valve discs 53 to 58 opposite the side where the piston main body 14 is arranged. The movable spring locking member 61 is provided on the side of the spacer 60 opposite the side where the piston main body 14 is arranged.The spring 62 is provided on the side of the movable spring locking member 61 opposite to the side where the piston main body 14 is located. The fixed spring locking member 63 is provided on the side of the spring 62 opposite to the side where the piston main body 14 is located.

[0028] The valve disc 53, which is the axially closest of all the valve discs 53 to 58 to the valve body 14 and which can come into contact with and be separated from the inner seat 31 and the outer seat 32, has an annular shape. As shown in Fig. 3, on the inner diameter side, the valve disc 53 has an inner diameter portion 65 and a plurality of arcuate convex portions 66. The inner diameter portion 65 has a circumferential shape with a predetermined diameter. Each of the arcuate convex portions 66 is a partial protrusion extending radially inward from the inner diameter portion 65. The plurality of convex portions 66 are provided at equal angular intervals on the valve disc 53 to be provided at four or more positions (five in the illustrated example). The inner diameter portion 65 has a smaller diameter than that of the inner seat 31, which in Fig. 1, ie a smaller diameter than that of the peripheral wall surface of the concave landing portion 35.

[0029] The valve disc 53 is fitted over the cylindrical member 47. An inner diameter of the inner diameter portion 65 of the valve disc 53 is slightly larger than that of the flange portions 49 and the sliding guide portion 50 of the cylindrical member 47. An inner diameter of a circle passing through the vertices of the plurality of convex portions 66, which corresponds to the smallest diameter (hereinafter, the circle obtained by connecting the vertices of the convex portions 66 is referred to as the "smallest diameter portion") on the inner circumference of the valve disc 53, is smaller than that of the largest diameter portion of each of the flange portions 49 and is slightly larger than that of each of the engaging grooves 48.In other words, the largest diameter portion of each of the flange portions 49 has a larger diameter than that of the smallest diameter portion of the inner circumference of the valve disc 53, which is the closest one of the plurality of valve discs 53 to 58 to the piston main body 14.

[0030] The inserted shaft portion 21 of the piston rod 16 is inserted through the valve disc 53. In addition, the valve disc 53 is fitted over the cylindrical member 47. When the valve disc 53 is fitted over the cylindrical member 47, the plurality of convex portions 66 are elastically deformed by one of the flange portions 49. When the convex portions 66 move to the position of one of the engaging grooves 48 (the upper one of the engaging grooves 48 shown in Fig. 1), the plurality of convex portions 66 elastically recovers to fit into one of the engagement grooves 48 as shown in Fig. 4. In this way, the plurality of convex portions 66 are engaged with the engaging groove 48, and thus the valve disc 53 is radially disposed with respect to the cylindrical member 47. In this state, due to a difference in diameter between an inscribed circle formed by the plurality of convex portions 66 and the flange portions 49 and the sliding guide portion 50, it is difficult for the valve disc 53 to move outside the engaging groove 48 into which the valve disc 53 is fitted. Therefore, the valve disc 53 is prevented from being removed from the cylindrical member 47.

[0031] As in Fig. 3, the valve disc 53 has an outer diameter portion 69 and a plurality of groove portions 70 provided at equal angular intervals in a circumferential direction on the outer diameter side. The outer diameter portion 69 has a circumferential shape with a predetermined diameter. Each of the groove portions 70 is partially concave radially inward from the outer diameter portion 69 to form an arc-like shape. The outer diameter portion 69 has an outer diameter of the valve disc 53 as the largest diameter thereof and has a larger diameter than an outer diameter of the outer seat 32, as shown in Fig. 1. An inscribed circle formed by bottom portions of the plurality of groove portions 70 has a smaller diameter than the inner diameter of the outer seat 32. In this way, even when the valve disc 53 abuts against the outer seat 32, the lines 26 are brought into communication with the lower chamber 13. While the valve disc 53 abuts against the outer seat 32, flow paths (orifices) each having a small flow path area are formed between the valve disc 53 and the groove portions 70 to bring the lines 26 into communication with the lower chamber 13. On the other hand, when the valve disc 53 is separated from the outer seat 32, the lines 26 are opened to bring the lines 26 into communication with the lower chamber 13 with a larger flow path area than that of the orifices described above.

[0032] As in Fig. 4, the valve disc 54 abutting against the valve disc 53 and the valve disc 55 abutting against the valve disc 54 have the same annular shape. The valve discs 54 and 55 serve to apply a biasing force to the valve disc 53 in a valve closing direction. On the inner diameter side, each of the valve discs 54 and 55 has the same diameter as that of the inner diameter portion 65 of the valve disc 53 and has a circumferential shape with a predetermined diameter over the entire circumference. On the other hand, on the outer diameter side, each of the valve discs 54 and 55 has the same diameter as that of the outer diameter portion 69 of the valve disc 53 and has a circumferential shape with a predetermined diameter over the entire circumference.The inserted shaft portion 21 of the piston rod 16 and the cylindrical member 57 provided over the entire inserted shaft portion 21 are inserted through the valve discs 54 and 55. In other words, the valve discs 54 and 55 are fitted over the cylindrical member 47.

[0033] The valve disc 56, which abuts the valve disc 55, the valve disc 57, which abuts the valve disc 56, and the valve disc 58, which abuts the valve disc 57, have the same annular shape. The valve discs 56 to 58 serve to apply a biasing force to the valve disc 53 in the valve closing direction. On the inner diameter side, each of the valve discs 56 to 58 has the same inner diameter as that of the valve discs 54 and 55 and has a circumferential shape with a predetermined diameter over the entire circumference. On the outer diameter side, each of the valve discs 56 to 58 has a smaller diameter than that of the valve discs 54 and 55 and has a circumferential shape with a predetermined diameter over the entire circumference.The inserted shaft portion 21 of the piston rod 16 and the cylindrical member 47 provided on the inserted shaft portion 21 are inserted through the valve discs 56 to 58. In other words, the valve discs 56 to 58 are fitted onto the cylindrical member 47.

[0034] The spacer 60, which is in Fig. 1, which abuts against the valve disc 58, has an annular shape. On the inner diameter side, the spacer 60 has the same diameter as that of the valve discs 56 to 58 and has a circumferential shape with a predetermined diameter over the entire circumference. On the outer diameter side, the spacer 16 has a smaller outer diameter than that of the valve discs 56 to 58 and has a circumferential shape with a predetermined diameter over the entire circumference. Further, the spacer 60 is formed to have a greater thickness than that of the valve discs 53 to 58. The inserted shaft portion 21 of the piston rod 16 and the cylindrical member 47 provided on the inserted shaft portion 21 are inserted through the spacer 60. As a result, the spacer is radially positioned with respect to the cylindrical member 47 and the piston rod 16.

[0035] The movable spring locking member 61, which abuts against the spacer 60 described above, has an annular shape. The movable spring locking member 61 includes a cylindrical portion 73 and a locking flange portion 74. The locking flange portion 74 extends radially outward from one axial end of the cylindrical portion 73 to form an annular shape. The inserted shaft portion 21 of the piston rod 16 and the cylindrical member 47 provided over the entire shaft portion 21 are inserted through the movable spring locking member 61. At the time of insertion, the movable spring locking member 61 is retained to be slidable on the sliding guide portion 50 of the cylindrical portion 47. As a result, the movable spring locking member 61 is axially movable while being radially positioned with respect to the piston rod 16.In other words, the cylindrical member 47 is inserted into the movable spring locking member 61. The sliding guide portion 50, on which the movable spring locking member 61 slides, is provided on the cylindrical member 47 on the side of the flange portions 49 closest to the piston main body 14, the side axially opposite to the side where the piston main body 14 is located. The abutment of the valve disc 58 against the movable spring locking member 61 allows preventing the valve discs 53 to 58 from deforming in the valve-opening direction beyond a defined degree.

[0036] The fixed spring locking member 63 includes a stepped portion 80 and a locking flange portion 81. The stepped cylindrical portion 80 includes a small-diameter cylindrical surface 77, an inclined surface 78, and a large-diameter cylindrical surface 79. The small-diameter cylindrical surface 77 has a predetermined diameter. The inclined surface 78 has a diameter that increases upon separation in the axial direction from the small-diameter cylindrical surface 77. The large-diameter cylindrical surface 79 is disposed on the side of the inclined surface 78 opposite to the side on which the small-diameter cylindrical surface 77 is disposed and has a predetermined diameter larger than that of the small-diameter cylindrical surface 77.The locking flange portion 81 extends radially outward from one end of the stepped cylindrical portion 80 located on the large-diameter cylinder surface 79 side in the axial direction to form an annular shape. An internal thread 82 is formed on an inner peripheral portion of the stepped cylindrical portion 80 located on the locking flange portion 81 side in the axial direction. The fixed spring locking member 63 is threadably engaged with a threaded shaft portion 22 of the piston rod 16 via the internal thread 82, while the inserted shaft portion 21 of the piston rod 16 is inserted into the fixed spring locking member 63 on the side of the stepped cylindrical portion 80 axially opposite to the side where the locking flange portion 81 is provided.In this state, one end of the fixed spring locking member 63 in the axial direction abuts against one end of the cylindrical member 47 in the axial direction, so that the fixed spring locking member 63 presses the other end of the cylindrical member in the axial direction against the piston main body 14. Specifically, the fixed spring locking member 63 functions as a nut for retaining the cylindrical member 47 between the fixed spring locking member 63 and the piston main body 14.

[0037] A spring 62 composed of a compression coil spring is interposed between the locking flange portion 74 of the movable spring locking member 61 and the locking flange portion 81 of the fixed spring locking member 63, through which the inserted shaft portion 21 of the piston rod 16 is inserted. A biasing force of the spring 62 is transmitted to the valve discs 53 to 58 through the intermediary of the movable spring locking member 61 and the spacer 60. The movable spring locking member 61, the spring 62, and the fixed spring locking member 63 constitute a spring force applying mechanism (spring force applying means) 84 for applying a force in the valve-closing direction to the valve discs 53 to 58 independently of the force applied by the valve discs 53 to 58.Note that a level difference is provided so that the height of the outer seat 32 in the axial direction of the piston main body 14 toward the lower chamber 13 is greater than that of the inner seat 31. Therefore, when the valve discs 53 to 58 are pressed by the biasing force of the spring 62 through the mediation of the movable spring lock member 61 and the spacer 60, the valve disc 53 abutting against the inner seat 31 and the outer seat 32 to be brought into close contact therewith is slightly deflected, so that the outer peripheral side thereof is brought closer to the spring 62 in the axial direction of the piston main body 14 than the inner peripheral side thereof. Consequently, the valve disc 54 abutting against the valve disc 53 and the valve disc 55 abutting against the valve disc 54 are also deflected as in the case of the valve disc 53.As a result, the valve discs 54 to 55 bias the valve disc 53 to bring the valve disc 53 into close contact with the outer seat 32.

[0038] The damping force generating mechanism 29 includes an annular disc valve 90, an annular spacer 91, and an annular valve limiting member 92. The disc valve 90 can simultaneously seat on the inner seat 41 and the outer seat 42. The spacer 91 is provided on the side of the disc valve 90 opposite the side where the piston main body 14 is located. The valve limiting member 92 is provided on the side of the spacer 91 opposite the side where the piston main body 14 is located.

[0039] The disc valve 90, which can contact and be separated from the inner seat 41 and the outer seat 42, has an annular shape. On the inner diameter side, the disc valve 90 has a circumferential shape with a predetermined diameter smaller than that of the inner seat 41 and the attachment seat 40. On the outer diameter side, the disc valve 90 has a circumferential shape with a predetermined diameter larger than that of the outer seat 42. Through holes 94 are formed between the inner seat 41 and the attachment seat 40 to axially pass through the disc valve 90. The through holes 94 bring the conduits 26 into communication with the upper chamber 12. The inserted shaft portion 21 of the piston rod 16 is inserted through the disc valve 90. As a result, the disc valve 90 is radially disposed with respect to the piston rod 16.The disc valve 90 forms a flow path (orifice) having a small flow path area with the conduit grooves (not shown) formed on the outer seat 42 while abutting against the outer seat 42 to bring the conduits 27 into communication with the upper chamber 12. On the other hand, when the disc valve 90 separates from the outer seat 42, the conduits 27 are opened to be brought into communication with the upper chamber 12 with a larger flow path area than that of the orifice.

[0040] A spacer 91, which abuts the disc valve 90, has an annular shape. On the inner diameter side, the spacer 91 has the same inner diameter as that of the disc valve 90 and forms a circumferential shape with a predetermined diameter over the entire circumference. On the outer diameter side, the spacer 91 has a smaller outer diameter than the diameter of the through holes 94 of the disc valve 90 and forms a circumferential shape with a predetermined diameter over the entire diameter. The spacer 91 is formed to have a greater thickness than that of the disc valve 90. The inserted shaft portion 21 of the piston rod 16 is inserted through the spacer 91. As a result, the spacer 91 is arranged radially with respect to the piston rod 16.

[0041] The valve limiting member 92, which abuts against the spacer 91, has an annular shape. On the inner diameter side, the valve limiting member 92 has the same inner diameter as that of the spacer 91 and forms a circumferential shape with a predetermined diameter over the entire circumference. On the outer diameter side, the valve limiting member 92 has the same outer diameter as that of the disc valve 90 and forms a circumferential shape with a predetermined diameter over the entire circumference. Further, the valve limiting member 92 is shaped to have a greater thickness than that of the spacer 91. The inserted shaft portion 21 of the piston rod 16 is inserted through the valve limiting member 92. As a result, the valve limiting member 92 is positioned radially with respect to the piston rod 16.An annular level difference portion 96, which forms a slight level difference to be located on the piston rod main body 14 side in the axial direction, is formed on the outer peripheral portion of the valve limiting member 92. Through holes 97 are formed at the positions radially inner side of the level difference portion 96 of the valve limiting member 92 to axially pass through the valve limiting member 92. The through holes 97 constantly communicate the lines 26 with the upper chamber 12 through the through holes 94 of the disc valve 90. Separation of the disc valve 90 from the outer seat 42 communicates the lines 27 with the upper chamber 12 through a radially extending gap between the disc valve 90 and the piston 11.At this time, the valve limiting member 92 limits the deformation of the disc valve 90 in the valve opening direction beyond a predetermined level.

[0042] To manufacture the piston 11 and the damping force generating mechanisms 28 and 29, on the piston rod 16, the valve limiting member 92, the spacer 91, the disc valve 90, and the piston 11 (including the sliding member 15 previously disposed on the piston main body 14) are stacked in this order on an end surface of the main shaft portion 20 located on the inserted side of the shaft portion 21, while inserting the threaded shaft portion 22 and the inserted shaft portion 21 in the state where the threaded shaft portion 22 of the piston rod 16 is tapered at an upper end, for example. On the other hand, regardless of the above-mentioned operation, the valve disc 53 is fitted over the cylindrical member 47 from one side in the axial direction to fit into one of the engagement grooves 48 located on one side in the axial direction.While the threaded shaft portion 22 and the inserted shaft portion 21 are inserted through the cylindrical member 47, the cylindrical member 47 is disposed in the abutment concave portion 35 of the piston 11. Next, the valve discs 54 to 58, the spacer 60, the movable spring locking member 61, and the spring 62 are stacked in this order on the valve disc 53 while the cylindrical member 47 is inserted therethrough. Subsequently, the fixed spring locking member 63 is threadably engaged with the threaded shaft portion 22. Note that at the time of engagement of the valve disc 53 with the cylindrical member 47, which is performed independently, the valve discs 54 to 58, the spacer 60, and the movable spring locking member 61 may be stacked in this order beforehand.The piston rod 21 can be inserted through the set of the above-mentioned elements so that the set of the above-mentioned elements is arranged on the piston 11.

[0043] As a result, the valve restrictor 92, the spacer 91, the disc valve 90, the piston 11, and the cylindrical member 47 are interposed between the end surface of the main shaft portion 20 located on the side of the inserted shaft portion 21 and an end surface of the fixed spring locking member 63 located on the side opposite the locking flange portion 81 of the stepped cylindrical portion 80, so as to be integrally fixed to the piston rod 16. As a consequence, the fixed spring locking member 63 itself is integrally fixed to the piston rod 16. Further, the valve discs 53 to 58, the spacer 60, the movable spring locking member 61, and the spring 62 are retained between the locking flange portion 81 of the fixed spring locking member 63 and the piston 11.

[0044] Alternatively, as in Fig. 5, a temporary fixing jig 104 is prepared. The temporary fixing jig 104 includes a large-diameter shaft portion 101, an inserted shaft portion 102, and an inclined shaft portion 103. The large-diameter shaft portion 101 is formed at a lower portion of the temporary fixing jig 104. In a middle portion of the temporary fixing jig 104, the inserted shaft portion 102, which has a smaller diameter than that of the large-diameter shaft portion 101 and has the same diameter as that of the inserted shaft portion 102, is formed. The inclined shaft portion 103, which is inclined to a point, is formed at an upper end of the temporary fixing jig 104.The valve restrictor member 92, the spacer 91, the disc valve 90, and the piston 11 are stacked in this order on one end surface of the large-diameter shaft portion 101 on the side of the inserted shaft portion 102, while the inclined shaft portion 103 and the inserted shaft portion 102 are inserted through the above-mentioned stacked members. On the other hand, the valve disc 53 is fitted over the outer side of the cylindrical member 47 from one side in the axial direction to be fitted into one of the engaging grooves 48 located on one side in the axial direction. The cylindrical member 47 is arranged in the abutment concave portion 35 of the piston 11, while the inserted shaft portion 102 is inserted into the cylindrical member 47.Next, the valve discs 54 to 58, the spacer 60, and the movable spring locking member 61 are stacked in this order on the valve disc 53, while the cylindrical member 47 is inserted through the above-mentioned members. Subsequently, the set of the above-mentioned members is removed from the temporary fixing jig 104. Subsequently, the set of members is directly placed on the end surface of the main shaft portion 20 on the side of the inserted shaft portion 21, while the threaded shaft portion 22 and the inserted shaft portion 21 of the piston rod, which are retained so that the threaded shaft portion 22 is positioned at the upper end, are inserted through the set of members.Next, after the spring 62 is mounted on the movable spring locking member 61, the mounted spring locking member 63 is threadably engaged with the threaded shaft portion 22. Note that even in this case, the valve discs 53 to 58, the spacer 60, and the movable spring locking member 61 may be previously mounted on the cylindrical member 47, so that the set of members obtained by the mounting can be mounted on the piston 11 while inserting the piston rod 21 therethrough.

[0045] As another alternative, as in Fig.6, a temporary fixing jig 111 is prepared. The temporary fixing jig 111 includes a large-diameter portion 106, an inserted shaft portion 107, an inclined shaft portion 108, an inserted shaft portion 109, and an inclined shaft portion 110. The large-diameter shaft portion 106 is formed at a lower portion of the temporary fixing jig 111. In a lower central portion of the temporary fixing jig 111, the inserted shaft portion 107, which has a smaller diameter than that of the large-diameter shaft portion 106 and the same diameter as that of the inserted shaft portion 11, is formed. The inclined shaft portion 108 is formed at an intermediate central portion of the temporary fixing jig 111.The inserted shaft portion 109, which has a slightly smaller diameter than that of the smallest diameter of the internal thread 82 of the fixed spring locking member 63, is formed at an upper center portion of the temporary fixing jig 111. The inclined shaft portion 110, which is inclined to a point, is formed at an upper end of the temporary fixing jig 111. The valve restrictor member 92, the spacer 91, the disc valve 90, and the piston 11 are stacked in this order on an end surface of the large-diameter shaft portion 106 on the inserted shaft portion 107 side, while the inclined shaft portion 110, the inserted shaft portion 109, the inclined shaft portion 108, and the inserted shaft portion 107 are inserted through the above-mentioned stacked members.On the other hand, independent of the above-described operation, the valve disc 53 is fitted over the outer side of the cylindrical member from one side in the axial direction to be engaged with one of the engagement grooves 48 located on one side in the axial direction. The cylindrical member 47 is placed in the abutment concave portion 35 of the piston 11, while the inclined shaft portion 110, the inserted shaft portion 109, the inclined shaft portion 108, and the inserted shaft portion 107 are inserted into the cylindrical member 47. Next, the valve discs 54 to 58, the spacer 60, the movable spring locking member 61, the spring 62, and the fixed spring locking member 63 are stacked in this order on the valve disc 53, while the cylindrical member 47 is inserted through the above-mentioned stacked members.Next, a set of the above-mentioned elements is removed from the temporary fixing jig 111. Subsequently, the set of elements is directly arranged on the end surface of the main shaft portion 20 on the side of the inserted shaft portion 21, while the threaded shaft portion 22 and the inserted shaft portion 21 of the piston rod 16, which are retained so that the threaded shaft portion 22 is located at the upper end, are inserted through the set of elements. Next, after the spring 62 is arranged on the movable spring locking member 61, the fixed spring locking member 63 is threadably engaged with the threaded shaft portion 22.It should be noted that even in this case, the valve discs 53 to 58, the spacer 60 and the movable spring locking member 61 may be previously combined with the cylindrical member 47 so that a set of the elements obtained by the attachment can be arranged on the piston 11 while the piston rod 21 is inserted therethrough.

[0046] Here, during the extension stroke in which the piston rod 16 moves toward the extension side, the oil flows from the upper chamber 12 into the lower chamber 13 through the passages 26. When a speed of the piston (hereinafter referred to as "piston speed") is within a very low speed range, the oil fluid introduced from the upper chamber 12 into the passage 26 substantially flows into the lower chamber 13 through the constant openings formed by the outer seat 32 formed on the piston 11 and the groove portions 70 of the valve disc 53 abutting against the outer seat 32. At the time of the flow of the oil fluid, a damping force having an opening characteristic (damping force substantially proportional to a square of the piston speed) is generated.

[0047] Furthermore, when the piston speed increases to reach a low speed range, the oil fluid introduced from the upper chamber 12 into the conduits 26 has a high pressure at the location where the oil fluid flows out toward the valve discs 53 to 58. As a result, the oil fluid substantially passes between the valve disc 53 and the outer seat 32 to flow into the lower chamber 13, while starting to deform the valve discs 53 to 58 at the outer peripheral portion of the spacer 60 as a starting point. Therefore, the damping force having a valve characteristic (damping force substantially proportional to the piston speed) is generated.

[0048] Furthermore, as the piston speed further increases, the oil fluid introduced from the upper chamber 12 into the conduit 26 has a further increasing pressure at the position where the oil fluid flows out toward the valve discs 53 to 58. When the pressure of the oil fluid exceeds a reaction force of the spring 62, the spring 62 is compressed. While the valve discs 53 to 58, the spacer 60, and the movable spring locking member 61 are separated from the outer seat 32 and the inner seat 31, the oil fluid passes between the valve disc 53 and the outer seat 32 to flow into the lower chamber 13. Therefore, a damping force with a characteristic of the conduits 26 (the damping force is substantially proportional to the piston speed with a smaller gradient than that of the valve characteristic described above) is generated.Note that at this time, the axial length of the groove bottom surface 48a is adjusted so that the valve disc 53 moves within the range of the groove bottom surface 48a of the corresponding one of the engaging grooves 48 without being removed from the corresponding one of the engaging grooves 48. Further, the axial length of the sliding guide portion 50 is adjusted so that the spring locking member 61 moves within the range of the sliding guide portion 50 of the cylindrical member 47.

[0049] During a displacement stroke (contraction) in which the piston rod 16 moves toward the compression side, the oil fluid flows through the passages 27 from the lower chamber 13 toward the upper chamber 12. When the piston speed is within the very low speed range, the oil fluid introduced from the lower chamber 13 into the passage 27 substantially flows into the upper chamber 12 through the constant orifice formed by the passage grooves (not shown) formed on the outer seat 42 of the piston 11 and through the disc valve 90 abutting the outer seat 42. At this time, a damping force having the opening characteristic (damping force substantially proportional to the square of the piston speed) is generated.

[0050] Furthermore, when the piston speed increases to reach the low speed range, the oil fluid introduced from the lower chamber 13 into the conduits 27 substantially passes between the disc valve 90 and the outer seat 42 to flow into the upper chamber 12 while the disc valve 90 is opened. Therefore, a damping force with the valve characteristic (damping force substantially proportional to the piston speed) is generated.

[0051] In the damper described in the above-cited JP S57-137735 A, a member inserted into a disc valve and a spring force applying device for biasing the disc valve in a valve-closing direction through which a piston rod is inserted are engaged with the piston rod by means of a thread. Therefore, the insertion / fixing operation becomes complicated.

[0052] On the other hand, according to the above-described embodiment, the cylindrical member 47 inserted into the valve discs 53 to 58 and the spring force applying mechanism 84 allow the piston rod 16 to pass therethrough without being threadably engaged with the piston rod 16. Therefore, the insertion / fixing operation can be simplified.

[0053] Furthermore, if the cylindrical member inserted into the disc valves and the spring force applying device is pressed to be fitted into the inner seat of the piston main body, a pressing process is complicated. In addition, there is a possibility of deformation of a seating surface of the inner seat due to pressing. Furthermore, if the cylindrical member cannot be pressed normally, the following problems occur. For example, the piston main body, especially the inner seat, will be damaged. If the cylindrical member is fitted crookedly, the disc valves may not be preferentially seated on the inner seat and the outer seat, causing oil fluid leakage. In addition, the disc valves may not move preferentially.

[0054] On the other hand, according to the above-described embodiment, the cylindrical member 47, which is inserted into the valve discs 53 to 58 and the spring force applying mechanism 84, is provided with the radially extending gap provided on the inner side of the inner seat 31 of the piston main body 14. Therefore, pressing is not required, thereby simplifying the operation (insertion / fixing). In addition, the above-mentioned problems due to abnormal pressing can be prevented from occurring.

[0055] The flange portions 49 are formed on the outer periphery of the cylindrical member 47 of the piston main body 14 side. The largest diameter portion of each of the flange portions 49 is larger than the smallest diameter portion of the inner periphery of the valve disc 53, which is the closest one of the valve discs 53 to 58 to the piston main body 14. Therefore, the valve disc 53 can be prevented from being removed from the cylindrical member 47. Due to the structure in which the cylindrical member 47 is provided with the radially extending gap provided on the inner side of the inner seat 31 of the piston main body 14, the cylindrical member 47 sometimes moves relative to the piston main body 14 due to the insertion / fixing process.Even in such states, the valve disc 53 and the valve discs 54 to 58 stacked thereon can be prevented from being removed from the cylindrical member 47. Except in the case where the above-mentioned structure for preventing the removal of the valve disc 53 from the cylindrical member 47 is employed, the cylindrical member 47 moves relative to the piston main body 14 during the insertion / attachment process described above, and consequently, the valve discs 53 to 58 that have been arranged on the piston main body 14 are disadvantageously removed from the cylindrical member 47. Subsequently, there is a fear that any one of the valve discs 53 to 58 will be clamped between the cylindrical member 47 and the piston main body 14.If the fixed spring locking member 63 is threadably engaged with the piston rod 16 without noticing the thus clamped valve disc, there is a fear that the clamped valve disc may be deformed or damaged. In this embodiment, such a problem does not occur.

[0056] On the cylindrical member 47, the flange portions 49 are formed on axially opposite sides thereof. Therefore, the alignment limit at the time of insertion / fixing is eliminated to prevent erroneous insertion / fixing. As a result, operability in the insertion / fixing process is improved.

[0057] The cylindrical member 47 includes the sliding movement guide portion 50 on which the movable spring locking member 61 of the spring force applying mechanism 84 slides, which is provided on the opposite side of the upper flange portion 49 to the piston main body 14. Therefore, the movement of the movable spring locking member 61 is preferably permitted.

[0058] The smallest diameter portion of the inner circumference of the valve disc 53, which is the closest of the valve discs 53 to 58 to the valve body 14, is formed by the plurality of convex portions 66 corresponding to the partial protrusions formed on the inner circumferential diameter portion 65. Therefore, the valve disc 53 can preferentially pass over the corresponding one of the flange portions 49 to be engaged with the corresponding one of the engaging grooves 48 into which the valve disc 53 is fitted. Consequently, operability in the insertion / fixing operation is improved. Note that each of the engaging grooves 48 is not required to have the annular shape and may be a groove formed intermittently in the circumferential direction, which is concave to correspond to the positions of the convex portions 66.

[0059] By providing at least four convex portions 66, the valve disc 53 can be axially moved while appropriately restricting its inclination. Furthermore, the valve disc 53 can be prevented from being removed from the corresponding one of the engagement grooves 48 into which the valve disc 53 is fitted.

[0060] Forming the inner seat 31 on the piston main body 14 eliminates the need for a member for controlling the initial deflection of the valve discs 53 to 58. At the same time, since a height of the inner seat 31 is stabilized, a variation of an initial deflection of the valve discs 53 to 58 can be limited.

[0061] It should be noted that although the application of the present invention to the damping force generating mechanism 28 provided on the piston 11 of the shock absorber has been described as an example, any damping force generating mechanism provided on the shock absorber can be used, regardless of whether the damping force generating mechanism is of the single-cylinder type or the multi-cylinder type. The present invention is also applicable to other various damping force generating mechanisms, such as a base valve formed between a reservoir chamber provided between an internal cylinder and an external cylinder and a lower chamber in the internal cylinder in the multi-cylinder type cylinder.

[0062] According to the embodiment as described above, the damper has a structure including: a cylinder in which an operating fluid is enclosed; a piston slidably inserted into the cylinder to divide the interior of the cylinder into two chambers; a piston rod connected to the piston, the piston rod having at least one end extending out of the cylinder; a valve main body having a passage through which the operating fluid flows due to a sliding movement of the piston; a fixed stem inserted through a valve main body insertion hole formed through the valve body; an inner seat having an annular shape provided around the valve main body insertion hole to extend from the valve main body insertion hole; an outer seat having an annular shape provided on an outer peripheral side of the inner seat,to extend from the outer peripheral side of the inner seat and to enclose an opening of the conduit; wherein the disc valve has an annular shape capable of coming into contact with and being separated from the inner seat and the outer seat, the disc valve being configured to allow the fixed stem to pass through the disc valve; spring force applying means for allowing the fixed stem to be inserted through the spring force applying means to apply a force in a valve closing direction to the disc valve; and a cylindrical member for allowing the fixed stem to be inserted through the cylindrical member, the cylindrical member being inserted into the disc valve and the spring force applying means, in which: the cylindrical member is provided,to have a radially extending gap on an inner side of the inner seat of the valve body. As described above, the cylindrical member inserted into the disc valve and the spring force applying device has a structure to allow the attached stem to be inserted therethrough. Therefore, assembly can be simplified. In addition, the cylindrical member has a structure provided with the radially extending gap on the inner side of the inner seat of the valve main body. Therefore, pressing is not required, thereby simplifying the insertion / fixing process. As a result, problems due to abnormal pressing do not occur.

[0063] Further, the disc valve includes a plurality of valve discs, and the flange portion is formed on the outer periphery of the cylindrical member on the valve main body side. The largest diameter portion of the flange portion has a larger diameter than that of the smallest diameter portion of the inner periphery of the valve disc, which is the closest one of the plurality of valve discs to the valve main body. Therefore, even if the cylindrical member is unexpectedly moved relative to the valve main body during the insertion / fixing process, the valve disc can be prevented from being removed from the cylindrical member. As described above, it is more preferable to form the flange portion on the outer periphery of the cylindrical member on the valve main body side.However, even if the flange portion is not formed on the cylindrical member, in other words, if the cylindrical member is straight in the axial direction without any processing, pressing is not required. Therefore, the problem of complications in the insertion / fastening process due to pressing is avoided. When the flange portion is provided on the cylindrical member, the insertion / fastening process can be further simplified.

[0064] Furthermore, the second flange portion is formed on the cylindrical member on the side axially opposite to the side where the flange portion is provided. Therefore, alignment limitation during insertion / fastening is prevented, preventing erroneous insertion / fastening. As a result, the operability of the insertion / fastening operation is improved.

[0065] Furthermore, the large-diameter portion on which the spring force applying device slides is provided on the cylindrical member on the side axially opposite to the side on which the flange portion is provided. Therefore, the spring force applying device can be moved appropriately.

[0066] Furthermore, the smallest diameter portion of the inner circumference of the valve disc, which is closest to the plurality of valve discs of the valve body, is formed by the plurality of convex portions partially extending from the inner circumference diameter portion. Therefore, the valve disc can easily pass over the flange portion. Accordingly, the operability of the insertion / fastening operation is improved.

[0067] Furthermore, at least four convex portions are provided. Therefore, the valve disc can be moved axially while appropriately limiting its inclination. Furthermore, the valve disc can be prevented from being removed from the flange portion.

[0068] Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily recognize that many modifications to these exemplary embodiments are possible without materially departing from the novel teachings and advantages of this invention. Accordingly, it is intended to include all such modifications within the scope of this invention.

Claims

[1] Shock absorber, comprising: a cylinder (10) in which an operating fluid is enclosed; a piston (11) slidably inserted into the cylinder (10) to divide the interior of the cylinder (10) into two chambers; a piston rod (16) connected to the piston (11), the piston rod (16) having at least one end extending from the cylinder (10); a valve main body (14) having a passage (26) through which the operating fluid flows due to a sliding movement of the piston (11); a fixed shaft (21) inserted through a valve main body insertion hole (23) formed through the valve main body (14); an inner seat (31) having a ring shape provided around the valve main body insertion hole (23) to extend from the valve main body insertion hole (23); an outer seat (32) having a ring shape provided on an outer peripheral side of the inner seat (31) to extend from the outer peripheral side of the inner seat (31) and to enclose an opening of the conduit (26); a disc valve (53, 54, 55, 56, 57, 58) having an annular shape capable of coming into contact with and separating from the inner seat (31) and the outer seat (32), the disc valve (53, 54, 55, 56, 57, 58) allowing the fixed stem (21) to pass through the disc valve (53, 54, 55, 56, 57, 58); a spring force applying means (84) for applying a force in a valve closing direction to the disc valve (53, 54, 55, 56, 57, 58) while allowing the fixed stem (21) to be inserted through the spring force applying means (84); and a cylindrical member (47) through which the fixed shaft (21) is inserted, the cylindrical member (47) being inserted into the disc valve (53, 54, 55, 56, 57, 58) and the spring force applying device (84), wherein: a radially extending gap is defined between the cylindrical element (47) and an inner side of the inner seat (31), wherein the shock absorber further comprises a flange portion (49) formed on an outer periphery of the cylindrical member (47) on a side close to the valve main body (14), wherein the disc valve has a plurality of valve discs (53, 54, 55, 56, 57, 58), wherein a largest diameter portion of the flange portion (49) has a larger diameter than that of a smallest diameter portion of an inner circumference of one (53) of the valve discs (53, 54, 55, 56, 57, 58), and wherein a largest diameter portion of the flange portion (49) has a larger diameter than that of a smallest diameter portion of an inner periphery of one (53) of the plurality of valve discs (53, 54, 55, 56, 57, 58) disposed closest to the valve main body (14). [2] A shock absorber according to claim 1, wherein the cylindrical member (47) includes a second flange portion (49) formed on the cylindrical member (47) on a side axially opposite to the side on which the valve main body (14) is provided. [3] A shock absorber according to claim 1 or 2, wherein the cylindrical member (47) includes a large-diameter portion (50) on which the spring force applying means (84) slides, which is provided on a side axially opposite to the side on which the valve main body (14) is provided. [4] A shock absorber according to any one of claims 1 to 3, wherein the smallest diameter portion of the inner circumference of said one of the plurality of valve discs (53, 54, 55, 56, 57, 58) is formed by a plurality of convex portions (66) corresponding to partial projections extending from an inner cylindrical diameter portion, said valve disc being the closest to said valve main body (14), said plurality of convex portions (66) being arranged in the circumferential direction. [5] A shock absorber according to claim 4, wherein the number of convex portions (66) is at least four.

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