Cylinder device

Abstract

Cylinder device comprising: a cylinder (11) containing a fluid sealed therein, a rod (22) with an end extending out of the cylinder, flow paths (94, 95) through which the fluid flows when the rod (22) moves, an annular valve element (76) provided with at least a portion of the flow paths and having a through-bore (81), a pin element (98) inserted through the through-bore (91) of the valve element (76), an annular disc valve (110) with the pin element (98) inserted therein, wherein the disc valve is selectively movable away from and into contact with an end face of the valve element (76) on both its inner and outer circumferences in order to open and close the flow paths accordingly, and a portion with an enlarged diameter (101, 140) provided on a section of the pin element (98) in one direction.in which the disc valve is movable away from one end face of the valve element to prevent the disc valve from falling off, wherein the valve element has a projecting section (84) around the through-bore at one end face, wherein the projecting section (84) is locally provided with circumferentially spaced grooves (91), each of the grooves (91) extending radially through the projecting section (84) to the through-bore, wherein the disc valve (110) has small-diameter sections (116) extending from an inner circumference to the grooves (91) therein, wherein the small-diameter sections are slidable relative to the pin element (98), wherein when the disc valve (110) is selectively moved away from and into contact with an end surface of the valve element (76) at both the inner and outer circumferences of the pin element (98),the small diameter sections (116) move within the grooves (91) and the distal ends (117) of the small diameter sections (116) slide relative to the pin element (98).

Description

BACKGROUND OF THE INVENTIONThe present invention relates to a cylinder device.A cylinder device is known in which a disk valve slides relative to a valve element having flow paths formed therein to selectively open and close the flow paths, as disclosed in JP S64-40 731A.U.S. Pat. No. 3,321,051 A forms further prior art.OBJECT OF THE INVENTIONCylinder devices have been required to obtain optimum valve characteristics.Accordingly, it is an object of the present invention to provide a cylinder device that can obtain optimum valve characteristics.The invention is defined by claim 1.To achieve the object described above, the present invention provides a cylinder device including: an annular valve element provided with at least a part of the flow paths and having a through hole; a pin member inserted through the through hole of the valve element; an annular valve disk having the pin member inserted therethrough and selectively movable on both inner and outer peripheries thereof away from and into contact with an inner surface of the valve element to open and close the flow paths, respectively; and an enlarged diameter part provided on a portion of the pin member in a direction in which the disk valve is movable away from an end surface of the valve element to prevent the disk valve from falling off. The valve element has a protrusion portion around the through hole at the one end surface thereof. The protrusion portion is locally provided with circumferentially spaced grooves. The disk valve has small diameter portions extending from the grooves from the inner periphery thereof. The small diameter portions are slidable relative to the pin member.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a partial sectional view of a shock absorber as a first embodiment of a cylinder device according to the present invention. FIG. 2 is a sectional view showing a base valve of the shock absorber as a first embodiment of the cylinder device according to the present invention. FIG. 3 is a plan view showing a base valve member of the shock absorber as the first embodiment of the cylinder device according to the present invention. FIG. 4 is a plan view showing a disk valve of the shock absorber as the first embodiment of the cylinder device according to the present invention. FIG. 5 is a sectional view showing a base valve of a shock absorber as a second embodiment of the cylinder device according to the present invention. FIG. 6 is a sectional view showing a base valve of a shock absorber as a third embodiment of the cylinder device according to the present invention.DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTSFirst EmbodimentA shock absorber as a first embodiment of a cylinder device according to the present invention will be explained below with reference to Figs. 1 to 4.As shown in FIG. 1, a shock absorber according to the first embodiment of the present invention has a cylinder 11 in which a fluid, for example, a liquid or a gas, is sealed. The cylinder 11 has an inner tube 12 and an outer tube 13 which has a larger diameter than the inner tube 12 and is concentrically provided to cover the inner tube 12. Thus, the cylinder 11 has a double-tube structure in which a storage chamber 14 is formed between the inner tube 12 and the outer tube 13.The inner pipe 12 of the cylinder 11 has a piston 17 slidably fitted therein, the piston 17 defining an upper chamber 18 and a lower chamber 19 in the inner pipe 12, i.e., the cylinder 11. the cylinder 11 comprises a hydraulic fluid and a gas sealed therein as fluids. Specifically, the upper chamber 18 and the lower chamber 19 have a hydraulic fluid sealed therein, and the storage chamber 14 has a hydraulic fluid and a gas sealed therein.The cylinder 11 includes a rod 22 inserted therein. one end of the rod 22 extends to the outside of the cylinder 11. the other end of the rod 22 extends into the inner pipe 12. the piston 17 is fixed to the other end of the rod 22 in the inner pipe 12 using a nut 23. The one end of the rod 22 extends to the outside of the cylinder 11 through a rod guide (not shown) and an oil seal (not shown) provided in the upper end of the cylinder 11 including the inner tube 12 and the outer tube 13.The rod 22 has a main shaft portion 25 and a fixing shaft portion 26 located at an end thereof inside the cylinder 11 and having a smaller diameter than the main shaft portion 25. The step 27 extends in a direction perpendicular to the axis of the main shaft portion 25. the fastening shaft portion 26 has an external thread 28 formed over a certain range of an end thereof remote from the main shaft portion 25. The external thread 28 is to be engaged with the nut 23.The piston 17 includes a substantially disk-shaped piston valve element 31 fitted into the inner pipe 12 of the cylinder 11 to divide the inside of the inner pipe 12 into two chambers, i.e., an upper chamber 18 and a lower chamber 19. The spool valve element 31 has an axially protruding cylinder portion 34 formed on the outer periphery of an end thereof closer to the lower chamber 19.The spool valve element 31 has a through bore 35 axially extending through the diametrical center thereof. The rod 22 is inserted through the through hole 35. The spool valve element 31 has an axially projecting annular projecting portion 36 formed at an end thereof axially opposite to the end thereof where the cylinder portion 34 is provided. The protrusion portion 36 is located radially outside the through hole 35. The spool valve element 31 further includes an axially protruding annular inner seat portion 37 located radially outward of the protrusion portion 36 and an axially protruding annular outer seat portion 38 located radially outward of the inner seat portion 37. Further, the spool valve element 31 has an axially projecting annular land portion 40 formed at the axial end thereof provided with the cylinder portion 34. The boss portion 40 is located radially outside the through hole 35. The piston valve element 31 further includes an axially protruding annular seat portion 41 located radially further outward than the boss portion 40 and further radially inward than the cylinder portion 34.The protrusion portion 36, the inner seat portion 37, and the outer seat portion 38 correspond to each other at a height in the axial direction of the spool valve element 31.The spool valve element 31 has a plurality of circumferentially spaced flow path recesses 43 (only one of which is shown in Fig. 1 because it is a sectional view). Each flow path recess 43 extends axially through the spool valve element 31, the flow path recess 43 opens at one axial end thereof between the boss portion 36 and the inner seat portion 37 and at the other axial end thereof between the boss portion 40 and the seat portion 41. further, the spool valve element 31 has a plurality of circumferentially spaced flow path recesses 44 (only one of which is shown in FIG. 1 because it is a sectional view). Each flow path recess 44 axially extends through the spool valve element 31, and the flow path recess 44 opens at one axial end thereof between the inner seat portion 37 and the outer seat portion 38 and at the other axial end thereof between the seat portion 41 and the cylinder portion 34.Each internal flow path recess 43 forms a flow path 45 that allows the hydraulic fluid to flow between the upper chamber 18 and the lower chamber 19. Each outer flow path recess 44 forms the outer flow path 46 that allows the hydraulic fluid to flow between the upper chamber 18 and the lower chamber 19. Thus, the flow paths 45 and 46 are provided in the spool valve element 31.The piston 17 includes a disk valve 50, a spacer 51, and a restriction member 52 at the axial end of the piston valve member 31 where the cylinder portion 34 is provided. The disk valve 50, the spacer 51, and the restriction member 52 are layered in the mentioned order from the spool valve member 31. Further, the piston 17 has a disk valve 55, a spacer 56, a spring member 57, and a restriction member 58 at the axial end of the piston valve member 31 opposite to the axial end where the cylinder portion 34 is provided. The disk valve 55, the spacer 56, the spring member 57, and the restricting member 58 are layered in the mentioned order from the spool valve member 31.The disk valve 50 has a rod insertion bore 60 axially extending through the diametrical center thereof. The spacer 51 has a rod insertion hole 61 axially extending through the diametrical center thereof. The restriction member 52 has a rod insertion bore 62 axially extending through the diametrical center thereof. The disk valve 50, the spacer 51, and the restriction member 52 have inserted the attachment shaft portion 26 of the rod 22 through their respective rod insertion holes 60, 61, and 62. In this state, the disk valve 50, the spacer 51, and the restriction member 52 are clamped at their inner peripheral portions by the nut 23 and the spool valve member 31.The disk valve 55 has a rod insertion bore 63 axially extending through the diametrical center thereof. The spacer 56 has a rod insertion bore 64 axially extending through the diametrical center thereof. The spring member 57 has a rod insertion hole 65 axially extending through the diametrical center thereof. The restriction member 58 has a rod insertion bore 66 axially extending through the diametrical center thereof. The disk valve 55, the spacer 56, the spring member 57, and the restricting member 58 have inserted the fixing shaft portion 26 of the rod 22 through their corresponding rod insertion holes 63, 64, 65, and 66. In this state, the disk valve 55, the spacer 56, the spring member 57, and the restricting member 58 are clamped at their respective inner peripheral portions by the spool valve member 31 and the step 27 of the main shaft portion 25 of the rod 22.The disk valve 50, which is provided at the end of the spool valve element 31 closer to the lower chamber 19, has a slightly larger outer diameter than that of the seat portion 41, and abuts against both the boss portion 40 and the seat portion 41 of the spool valve element 31 to close the inner flow paths 45. The disk valve 50 is lifted from the seat portion 41 to open the flow paths 45 by the pressure in the upper chamber 18 being raised higher than the pressure in the lower chamber 19 by the piston 17 moving together with the rod 22 as the rod 22 moves to the extension side where the protrusion amount of the stage 22 from the cylinder 11 increases. Consequently, when the rod 22 moves to the extension side, the fluid flows from the upper chamber 18 to the lower chamber 19 through the internal flow paths 45 provided in the spool valve element 31. Thus, the disk valve element 50 functions as an extension disk valve that selectively opens and closes the flow paths 45. Thus, the flow paths 445 allow the fluid to flow therethrough when the rod 22 and the piston 17 move toward the extension side.The spacer 51 is smaller in outer diameter than the disk valve 50, the outer diameter of the spacer 51 is substantially equal to that of the boss portion 40, the restriction member 52 is larger in outer diameter than the spacer 51, the outer diameter of the restriction member 52 is slightly smaller than that of the disk valve 50, and when the disk valve 50 is deformed away from the seat portion 41 by a certain amount, the restriction member 52 abuts against the disk valve 50 to restrict further deformation of the disk valve 50.The disk valve 55 provided at an end of the spool valve element 31 closer to the upper chamber 18 has an outer diameter slightly larger than that of the outer seat portion 38 of the spool valve element 31. The disk valve 55 has a cut-out portion 68 located radially more inward than a position where the disk valve 55 abuts against the inner seat portion 37. The disk valve 55 allows the inner flow paths 45 to constantly communicate with the upper chamber 18 through the cut-out portion 68.The disk valve 55 abuts against the protrusion portion 36, the inner seat portion 37, and the outer seat portion 38 of the piston member 31 to close the outer flow paths 46. The valve element 55 is lifted from the outer seat portion 38 to open the outer flow paths 46 by the pressure in the lower chamber 19 being raised higher than the pressure in the upper chamber 18 by the piston 17 moving together with the rod 22 as the rod 22 moves to a compression side where the entry amount of the rod 22 into the cylinder 11 increases. Consequently, when the rod 22 moves to the compression side, the fluid flows from the lower chamber 19 to the upper chamber 18 through the outer flow paths 46 provided in the spool valve element 31. Thus, the disk valve 55 functions as a compression disk valve that selectively opens and closes the flow paths 46. Thus, the flow paths 46 allow the fluid to flow therethrough when the rod 22 and the piston 17 move toward the compression side.The spring member 57 abuts and presses the disk valve 55 in the axial direction of the lower chamber 19, whereby the disk valve 55 abuts against the spool valve member 31. The restriction member 58 has an outer diameter substantially equal to that of the disk valve 55. The restriction member 58 has a plurality of circumferentially spaced communication recesses 69 extending axially therethrough. The communication recesses 69 allow the inner flow paths 45 to constantly communicate with the upper chamber 18 through the cut-out portion 68. When the disk valve 55 is deformed away from the outer seat portion 38 by a certain amount, the restricting member 58 abuts against the disk valve 55 to restrict further deformation of the disk valve 55.The outer tube 13 includes a cylinder member 72 and a bottom cover member 73 fitted to the lower end of the cylinder member 72 to close the opening at the lower end of the cylinder member 72. The bottom cover member 73 is fitted to the inner periphery of the cylinder member 72 on the outer periphery thereof. In the fitted state, the bottom cover member 73 assumes a stepped configuration that protrudes further axially outward as the distance from the outer periphery to the center of the bottom cover member 73 increases. The bottom cover member 73 is sealingly secured to the cylinder member 72, for example, by welding.The inner pipe 12 has a base valve 71 provided at a lower end thereof. The base valve 71 defines the lower chamber 19 and the reservoir chamber 14 in the cylinder 11, and the base valve 71 includes a damping valve 103 that generates a compression damping force, and a suction valve 110 that allows the hydraulic fluid to flow from the reservoir chamber 14 into the lower chamber 19 without substantially generating a damping force during the extension stroke of the rod 22.The base valve 71 has an annular base valve element (valve element) 76 fitted into the inner tube 12 of the cylinder 11 to divide the interior of the cylinder 11 into two chambers, i.e., a lower chamber 19 and a storage chamber 14. The base valve member 76 has a step portion 77 formed on the outer periphery of the upper portion thereof. The step portion 77 has a smaller diameter than the lower part of the base valve member 76. the step portion 77 is fitted to the inner periphery at the lower end of the inner pipe 12. Further, the base valve member 76 has an annular protrusion foot 78 axially protruding from the outer periphery of the lower end thereof. The base valve member 76 abuts against the bottom cover member 73 at the protrusion foot 78. The boss foot 78 has a plurality of circumferentially spaced flow path grooves 79 extending radially therethrough. The flow path grooves 79 allow communication between the space between the inner tube 12 and the outer tube 13 and the space between the base valve 71 and the bottom cover member 73 to form the storage chamber 14.As shown in FIG. 2, the base member 76 has a through hole 81 axially extending through the diametrical center thereof. Further, the base valve member 76 has a protrusion portion 84 formed on a surface (an end surface) 76 aat an end thereof axially opposite to the end thereof where the protrusion foot 78 is provided. The protrusion portion 84 is located radially around the through hole 81 and axially protrudes in the shape of a conical cylinder. The base valve member 76 further includes an axially projecting annular inner seat portion 85 located radially outward than the protrusion portion 84, and an axially projecting annular outer seat portion 86 located radially outward than the inner seat portion 85. The boss portion 88 is located radially outside the through hole 81. The base valve member 76 further includes an axially projecting annular seat portion 89 located radially further outward than the boss portion 88 and radially further inward than the boss root 78.The inner seat portion 85 and the outer seat portion 86 correspond to each other in height in the axial direction of the base valve member 76. the protrusion portion 84 is higher in protrusion height than the inner seat portion 85 and the outer seat portion 86. the seat portion 89 is slightly higher in protrusion height than the boss portion 88.In this embodiment, as shown in FIG. 3, the protrusion portion 84 includes a plurality (specifically, three) of protrusions 90 divided from each other in the circumferential direction of the protrusion portion 84. The protrusions 90 have the same shape and are arranged at equal intervals in the circumferential direction. Each protrusion 90 has a part of an inner surface 90 aon a side closer to the through hole 81. The part of the inner surface 90a has a shape obtained by cutting out a part of the cylindrical surface concentric with and equal in diameter to the through hole 81. The outer surface 90 bis concentric with and larger in diameter than the through hole 81. Further, each protrusion 90 has a pair of side surfaces 90 cand 90 don both sides thereof in the circumferential direction of the protrusion portion 84. The side surfaces 90c and 90d are inclined at the same angle to come closer to each other as the distance from the projection proximal end to the projection distal end of the projection 90 increases, as shown in FIG. 3. Each protrusion 90 has a tip 90e at a protrusion distal end thereof. The tip 90e is substantially the same in shape but smaller than the projection proximal end. The tip 90e extends in a direction perpendicular to the axis of the base valve member 76.As mentioned above, the protrusion portion 84 includes a plurality of protrusions of the same shape spaced apart from each other in the circumferential direction of the base valve member 76. Consequently, the protrusion portion 84 is provided with the same number of grooves 81 as the number of the protrusions 90, each groove 91 being located between a pair of the circumferentially adjacent protrusions 90. Each groove 91 is locally defined by mutually opposite side surfaces 90c and 90d of a pair of adjacent protrusions 90 and a bottom surface 91a between the side surfaces 90c and 90d. The bottom surface 91 ais flush with an annular flat surface 95 abetween the protrusion portion 84 and the inner seat portion 85, and is parallel to the tip 90 e.The grooves 91 gradually narrow in width with the distance from the through hole 81 at the same height position. At the same radial position, the grooves 91 gradually narrow in width with the distance from the bottom surface 91 a. As a result, the bottom surface 91 agradually narrows in a width with the distance to the through hole 81. the distance between the mutually opposite side surfaces 90 cand 90 calso gradually decreases with the distance to the through hole 81 at the same height position. Note that the base valve member 76 is made of a sintered metal as mentioned above, and the radially outer circumferential surface of the protrusion portion 84 including a plurality of outer surfaces 90 bis tapered due to the sintering formation.As shown in FIG. 2, the base valve 76 includes a plurality of circumferentially spaced flow path recesses 92 Each flow path recess 92 has an axial end opening between the protrusion portion 84 and the inner seat portion 85. The other axial end of the flow path recess 92 opens between the boss portion 88 and the seat portion 89. Further, the base valve member 76 has a plurality of circumferentially spaced flow path recesses 93. Each flow path recess 93 has an axial end opening between the inner seat portion 85 and the outer seat portion 86. The other axial end of the flow path recess 93 opens at a position farther from the boss portion 88 than from the seat portion 89.Each internal flow path recess 92 defines a flow path 94 that allows hydraulic fluid to flow between the lower chamber 19 and the storage chamber 14. Each outer flow path recess 93 defines the outer flow path 95 that allows the hydraulic fluid to flow between the lower chamber 19 and the storage chamber 14. Thus, the flow paths 94 and 95 are provided in the base valve member 76.The base valve 71 includes a pin member 98. The pin member 98 has a circular columnar or cylindrical shaft portion 99 inserted through the through hole 81 of the base valve member 76. The pin member 98 further has a disc-shaped head portion 100 provided at one end of the shaft portion 99 and having a larger diameter than the shaft portion 99. A deformed (caulked, crimped or riveted) portion (enlarged diameter part) 101 is formed at the other end of the shaft portion 99 opposite to the end thereof where the head portion 100 is provided. The deformed portion 101 is enlarged to be larger in diameter than the shaft portion 99 by deformation (caulking, crimping, or riveting).The base portion 71 includes a disk valve 103 functioning as a damping valve, a spacer 104, and a restriction member 105 at the axial end of the base valve member 76 where the protrusion foot 78 is provided. The disk valve 103, the spacer 104, and the restriction member 105 are layered in the aforementioned order from the base valve member 76. Further, the base valve 71 includes a disk valve 110 functioning as a suction valve, a spring member 111, and a restriction member 112 at the axial end of the base valve member 76 opposite to the axial end where the protrusion foot 78 is provided. The disk valve 110, the spring member 111, and the restricting member 112 are layered in the aforementioned order from the base valve member 76.The disk valve 103 has a pin insertion hole 106 axially extending through the diametrical center thereof. The spacer 104 has a pin insertion hole 107 axially extending through a diametrical center thereof. The restriction member 105 has a pin insertion hole 108 axially extending through the diametrical center thereof. The disk valve 103, the spacer 104, and the restriction member 105 have inserted the shaft portion 99 of the pin member 98 through their corresponding pin insertion holes 106, 107, and 108. In this state, the disk valve 103, the spacer 104, and the restriction member 105 are clamped at their respective inner peripheral portions by the head portion 100 of the pin member 98 and the base valve member 76.The disk valve 110 is formed by press forming from a single plate member. The disk valve 110 is flat and annular as shown in FIG. 4. That is, the disk valve 10 includes an annular valve body portion 115 having constant inner and outer diameters, that is, a constant width in the radial direction, and a plurality (specifically, three, the same number as the number of the grooves 91) of tongue portions (small diameter portions) 116 extending radially inward from the inner periphery of the valve body portion 115 to form the small diameter portions of the disk valve 110. The tongue portions 116 have the same shape and extend from corresponding circumferentially equally spaced positions of the valve body portion 115 to the center of the valve body portion 115. Each tongue portion 116 is tapered in the radial direction. The distal end 117 of each tongue portion 116 has a semicircular shape and protrudes toward the center of the valve body portion 115. The tip of the distal end 117 is located at the smallest diameter position of the disk valve 110. The diameter of the disk valve 110 at the tips of the distal ends 117 of the tongue portions 116 is slightly larger than the diameter of the shaft portion 99 of the pin member 98.As shown in FIG. 2, the disk valve 110 has inserted therethrough the shaft portion 99 of the pin member 98 at a position closer to the center thereof than the distal ends 117 of all the tongue portions 116. With the tongue portions 116 respectively disposed in the grooves 91, the disk valve 110 is provided on the one end surface 76 aof the base valve member 76 on which the protrusion portion 84, the inner seat portion 85, and the outer seat portion 86 are formed. The disk valve 110 is selectively movable away from and in contact with the surface 76a at both the inner and outer peripheries thereof. When the disk valve 110 moves in this manner, the tongue portions 116 extend and move within the grooves 91, and the distal ends 117 at the inner circumferential ends of the tongue portions 116 slide relative to the shaft portion 99 of the pin member 98. the inner circumferential edge (large diameter portion) 118 of the valve body portion 115 is larger in diameter than a part of the disk valve 110 corresponding to the tongue portions 116 and faces the outer circumference of the protrusion portion 84. the disk valve 110 closes the flow rates 95 provided between the inner seat portion 85 and the outer seat portion 86 with the valve body portion 115 when abutting against the inner and outer seat portions 85 and 86 simultaneously. When the valve body portion 115 lifts from the inner seat portion 85 and the outer seat portion 86, the disk valve 110 opens the flow paths 95.The spring member 111 has a pin insertion hole 124 axially extending through the diametrical center thereof. The restriction member 112 has a pin insertion hole 125 axially extending through the diametrical center thereof. The spring member 111 and the restricting member 112 have inserted the shaft portion 99 of the pin member 98 through their corresponding pin insertion holes 124 and 125. In this state, the spring member 111 and the restricting member 112 are clamped at their inner peripheral portions by the protrusion portion 84 of the base valve member 76 and the enlarged diameter part 101 of the pin member 98. The enlarged diameter part 101 is provided in a forward direction of the disk valve 110 in which the disk valve 110 is movable away from the surface 76 aof the base valve member 76. The enlarged diameter part 101 prevents the disk valve 110 from falling off the pin member 98 through the spring member 111 and the restricting member 112.In assembling the base valve 71, the shaft portion 99 (before being deformed) of the pin member 98 is inserted through the following parts in the following order: the pin insertion hole 108 of the restriction member 105, the pin insertion hole 107 of the spacer 104, the pin insertion hole 106 of the disk valve 103, the through hole 81 of the base valve member 76, the space inside the plurality of tongue portions 116 of the disk valve 110, the pin insertion hole 124 of the spring member 111, and the pin insertion hole 125 of the restriction member 112. In this state, the end of the shaft portion 99 opposite to the end thereof provided with the head portion 100 protruding from the restricting member 112 is deformed toward the head portion 100. Consequently, the restricting member 105, the spacer 104, the disk valve 103, the base valve member 76, the spring member 111, and the restricting member 112 are restricted from movement by the head portion 100. Therefore, the shaft portion 99 is enlarged in diameter to clamp the aforementioned members without a gap in the axial direction. In this way, the enlarged diameter part 101 is formed. At this time, the base valve element 76 receives the deforming load inputted by the restricting member 112 and the spring member 111. In other words, the pin member 98 at the distal end thereof is deformed to form the enlarged diameter part 101, the deformation load being supported by the protrusion portion 84 of the base valve member 76.The disk valve 103 provided at the end of the base valve member 76 closer to the reservoir chamber 14 comprises a plurality of axially laminated, drilled single plate disks having the same outer diameter. The disk valve 103 has a slightly larger outer diameter than the seat portion 89. The disk valve 103 can close the internal flow paths 94 by abutting against both the land portion 88 and the seat portion 98 of the base valve member 76. The disk valve 103 lifts from the seat portion 89 as shown in FIG. 2 to open the internal flow paths 94 when the rod 22 moves to the compression side as shown in FIG. 1, and thus the piston 17 moves to the lower chamber 19, causing an increase in the pressure in the lower chamber 19. Thus, the internal flow paths 94 provided in the base valve 76 allow the fluid to flow from the lower chamber 19 to the storage chamber 14 when the rod 22 moves toward the compression side. Thus, the disk valve 103 functions as a compression disk valve that selectively opens and closes the flow paths 94 to generate a damping force. Thus, the flow paths 94 allow the fluid to flow therethrough when the rod 22 and the piston 17 move toward the compression side. Note that the disk valve 103 mainly performs the function of allowing the hydraulic fluid to flow through the lower chamber 19 into the reservoir chamber 14 to expel excess hydraulic fluid resulting from the entry of the rod 22 into the cylinder 11 together with the compression disk valve 55 provided on the piston 17 as shown in FIG. 1. Note that the compression disk valve may be used as a pressure reducing valve that releases the pressure in the cylinder when the pressure excessively rises.As shown in FIG. 2, the spacer 104 has a smaller outer diameter than that of the disk valve 103 and a slightly smaller than that of the boss portion 88, and the restricting member 105 has a slightly smaller outer diameter than that of the disk valve 103 and is substantially the same as that of the seat portion 89. When the disk valve 103 is deformed away from the seat portion 89 by a certain amount, the restricting member 105 abuts against the disk valve 103 to restrict further deformation of the disk valve 103.The disk valve 110 provided at the end of the base valve member 76 closer to the lower chamber 19 has a slightly larger outer diameter than that of the outer seat portion 86 The disk valve 110 allows the inner flow paths 94 to constantly communicate with the lower chamber 19 through the gaps between the tongue portions 116 located radially more inward than a position where the disk valve 110 abuts against the inner seat portion 85. As mentioned above, the disk valve 110 is selectively movable (in the axial direction) on both the inner and outer peripheries thereof from and in contact with the base valve member 76, and when the disk valve 110 moves in this manner, the distal ends 117 of the tongue portions 116 are guided by the shaft portion 99 of the pin member 98.The disk valve 110 closes the outer flow paths 95 with the valve body portion 115 abutting against both the inner and outer seat portions 85 and 86 of the base valve member 76. As shown in FIG. 1, when the rod 22 moves to the extension side and the piston 17 thus moves to the upper chamber 18, causing a reduction in the pressure in the lower chamber 19, the disk valve 110 moves along the protrusion portion 84 and lifts from both the outer and inner seat portions 86 and 85 to open the flow paths 95. Consequently, the external flow paths 95 provided in the base valve member 76 allow the fluid to flow from the storage chamber 14 to the lower chamber 19 when the rod 22 moves to the extension side. Thus, the disk valve 110 functions as an extension disk valve that selectively opens and closes the flow paths 95. Note that the disk valve 110 mainly performs the function of allowing the hydraulic fluid to flow from the reservoir chamber 14 into the lower chamber 19 substantially without resistance (with such a low resistance that no damping force is generated) to compensate for a shortage of the hydraulic fluid as a result of the rod 22 protruding from the cylinder 11 in cooperation with the extension disk valve 50 provided on the piston 17. thus, the interference paths 95 allow the fluid to flow therethrough when the rod 22 and the piston 17 move toward the extension side.The spring member 111 abuts and urges the disk valve 110 in the axial direction, thereby abutting the disk valve 110 against the base valve member 76. The restriction member 112 has an abutment portion 113 on the outer periphery thereof which axially protrudes toward the disk valve 110. The abutting portion 113 has a diameter slightly smaller than the outer diameter of the disk valve 110 and is substantially the same as the diameter of the outer seat portion 86 Thus, when the disk valve 110 moves in the direction to open the flow paths 95, the abutting portion 113 may abut against the disk valve 110 to stop the movement of the disk valve 110 without jamming the spring member 111 between the restricting member 112 and the disk valve 110. The restriction member 112 has a plurality of circumferentially spaced communication recesses 127. The communication recesses 127 extend axially through the restriction member 112 to allow the inner flow paths 94 to constantly communicate with the lower chamber 19 through the gaps between the tongue portions 116. When the valve element 110 rises by a certain amount from the inner and outer seat portions 85 and 86, that is, away from the surface 76 aof the base valve element 76, the restricting member 112 abuts against the valve body portion 115 of the disk valve 110 at the abutting portion 113 to further restrict raising of the disk valve 110. The outer diameter of the restriction member 112 is larger than the diameter of the inner circumferential edge 118 of the valve body portion 115 of the disk valve 110.The spring member 111 is a substantially plate-shaped spring, and includes a flat disk-shaped base 131 having a circular pin insertion hole 124 at the center thereof, and a plurality of elastic legs 132 extending radially outward from the outer periphery of the base 131 and obliquely in an axial direction of the base 131.The elastic legs 132 of the spring member 111 have a spring constant set to a minimum, so that even if they are deformed, the elastic legs 132 only generate a minimum necessary urging force to make the disk valve 110 abut against both the inner seat portion 85 and the outer seat portion 86. Therefore, the disk valve 110 can reliably keep the flow paths 95 closed by the urging force of the elastic legs 132, set that the pressure in the lower chamber 19 is not less than the pressure in the storage chamber 14. however, when the pressure in the lower chamber 19 becomes less than the pressure in the storage chamber 14, the disk valve 110 lifts from the inner seat portion 85 and the outer seat portion 86 to open the flow paths 95 immediately while pressing the easily deformable elastic legs 132. Thus, the disk valve 110 itself is a check valve that generates substantially no damping force. That is, the disk valve 110 functions as a check valve that opens at least at a piston speed of not more than 0.05 m / s.The shock absorber of the first embodiment described above operates as follows. When the rod 22 moves relative to the cylinder 11 together with the piston 17 toward the extension side, the size of the hydraulic fluid in the upper chamber 18 and the lower chamber 19 becomes less by an amount corresponding to the size through which the rod 22 protrudes from the cylinder 11. Consequently, the pressure in the lower chamber 19 becomes lower than the pressure in the reservoir chamber 14, and because the disk valve 110 is pressed only by the elastic legs 132 of the spring member 111 having a small spring constant, at this time, the disk valve 110 immediately lifts from both the outer seat portion 86 and the inner seat portion 85 to open the flow paths 95 to supply a hydraulic fluid from the reservoir chamber 14 into the lower chamber 19.After that, as the rod stroke changes from the extension stroke to the compression stroke, the amount of hydraulic fluid in the cylinder 11 becomes more as a result of the entry of the rod 22 into the cylinder 11. When the pressure in the lower chamber 19 becomes higher than the pressure in the storage chamber 14, the disk valve 110 is quickly abutted against both the outer seat portion 86 and the inner seat portion 85 by the urging force of the elastic legs 132 to close the flow paths 95.In the shock absorbers disclosed in JP S64-40 731A, sliding movement of the disk valve is guided by a protrusion portion formed around a through hole of the valve element through which a pin member is inserted. For example, the valve element is formed by sintering from the viewpoint of reducing manufacturing cost, etc. In the forming method by sintering, if both the upper and lower dies are split dies, hydraulic cylinders used for printing on the dies, for example, must be driven as well for each split die. In this regard, for an element having a very uneven shape, a part shape must necessarily be used to make the density uniform. However, a member having little unevenness in shape can be formed using a mold and a driving force, both of which are simply designed. Therefore, it is desired to use an integral mold for a member having a slightly uneven shape.As clearly shown in FIG. 2, in the embodiment of the present invention, the valve element 76 has the protrusion foot 78 raised in height to increase the flow path area of each flow path groove 79 between a pair of circumferentially spaced mutually adjacent portions of the protrusion foot 78. The purpose thereof is that the demand for improving the damping force characteristics has recently increased, and there is a demand for securing large flow paths in the valve element. In this embodiment, the protruding portion-side part of the valve element having less unevenness in shape is formed using an integral shape. When an integral mold is used for forming, it is necessary to provide a draft angle. If a draft angle is introduced, the outer circumferential surface of a resultant protrusion portion becomes a tapered surface. If the protrusion portion has a tapered outer circumferential surface, there will be a difference in radial gap between the inner circumference of the disk valve and the outer circumference of the protrusion portion according to the axial position of the protrusion portion, which makes it likely that the trace and the behavior of the disk valve become unstable, making it impossible to obtain stable valve characteristics. Certainly, the above-described problem can be solved by additionally performing cutting to remove the cone to form a cylindrical surface, or by providing, over the entire outer periphery of the protrusion portion, another component part having a cylinder outer periphery. In both cases, however, there will be an increase in cost.In this regard, according to the shock absorber of the first embodiment, the grooves 91 are provided in the protrusion portion 84 of the base valve member 76, and the distal ends 117 of the tongue portions 116 of the disk valve 110 are guided to slide through the grooves 91 by the pin member 98. Therefore, the trace and the behavior of the disk valve 110 are stabilized, and stable valve characteristics can be obtained. Because the grooves 91 can be formed in the protrusion portion 84 by sintering, it is not necessary to additionally perform a cutting process or provide an additional component part. Thus, an increase in cost can be prevented. In addition, because the height of the protrusion leg 78 can be increased, it is possible to ensure a large flow path area for each flow path groove 79 between a pair of circumferentially spaced mutually adjacent portions of the protrusion leg 78. Accordingly, damping force characteristics improve, and it is possible to improve running stability and running quality of a vehicle equipped with the shock absorber.In addition, when the pin member 98 is deformed to form an enlarged diameter part 101, the deformation load can be supported by the protrusion portion 84 of the base valve member 76. Therefore, it is not necessary to provide another component over the base valve member 76 to bear the deformation load, and thus it is possible to prevent the cost increase.In addition, the annular restricting member 112 restricting movement of the disk valve 110 away from the base valve member 76 can be clamped by the enlarged diameter part 101 and the protruding portion 84. Therefore, it is not necessary to provide an additional component for clamping the restriction member 112, and thus it is possible to prevent the cost increase.In addition, the protrusion portion 84 has an outer periphery that protrudes long to be opposed to the inner peripheral edge 118 of the valve body portion 115 of the disk valve 110. The protrusion portion 84 may be tapered when formed by sintering, in particular. Therefore, the above-described advantageous effects are more pronounced.Second EmbodimentNext, a second embodiment of the present invention will be explained with reference to FIG. 5, mainly with respect to the points in which the second embodiment is different from the first embodiment. Note that the elements and portions that are the same in the first and second embodiments are denoted by the same names and reference numerals.The second embodiment uses, as shown in FIG. 5, a restricting member 112A formed by slightly modifying the restricting member 112 of the first embodiment and an additional restricting member 135. The restricting member 112A is an annular member that does not have an axial protrusion portion (abutting portion 113 in the first embodiment) and passage recesses (communication recesses 127 in the first embodiment) axially extend therethrough except for a pin insertion hole 125. The restricting member 112A has an outer diameter larger than the outer diameter of the base 131 of the spring member 111 but smaller than the diameter of the inner peripheral edge 118 of the valve body portion 115 of the disk valve 110.The restriction member 135 is an annular member having a pin insertion hole 136 axially extending through the diametrical center thereof. The delimiting element 135 is a commercially available spacer disk. The restriction member 135 has a larger outer diameter than the diameter of the valve member 110 at the position of the distal ends 117 of the tongue portions 116, but smaller than the diameter of the inner circumferential edge 118 of the valve body portion 115. Further, the outer diameter of the restricting member 135 is not larger than the outer diameter of the base 131 of the spring member 111. The restricting member 135 is disposed between the spring member 111 and the base valve 76, and is clamped at its inner peripheral portion by the protrusion portion 84 of the base valve member 76 and the base 131 of the spring member 111.When the disk valve 110 moves away from the surface 76 a, that is, away from the inner and outer seat portions 85 and 86, of the base valve member 76 by a certain amount, the restricting member 135 abuts the distal ends 117 of the tongue portions 116 of the disk valve 110 to restrict further deformation of the disk valve 110.According to the second embodiment configured as mentioned above, the thick-wall restricting member 112A can be miniaturized. Therefore, it is possible to achieve weight and cost reductions. In addition, since a commercially available thin-wall spacer can be used as the restricting member 135, it is possible to prevent an increase in cost despite the additional restricting member 135.Third EmbodimentNext, a third embodiment of the present invention will be explained with reference to FIG. 6, mainly with respect to the points in which the third embodiment is different from the first embodiment. Note that elements and portions that are the same in the first and third embodiments are denoted by the same names and reference numerals.The third embodiment uses, as shown in FIG. 6, a pin member 98B formed by slightly modifying the pin member 98 of the first embodiment and a nut (enlarged diameter part) 140. The pin member 98B has an external thread 141 formed at the end of the shaft portion 99 opposite to the end thereof provided with the head portion 100. The nut 140 is threadedly engaged with the external thread 141 to clamp the restriction member 105, the spacer 104, the disk valve 103, the base valve member 76, the spring member 111, and the restriction member 112 by the nut 140 and the head portion 100 without performing deformation. Thus, the nut 140 prevents the disk valve 110 from falling off the pin member 98B.According to the third embodiment arranged as described above, the nut 140 and the head portion 100 are used to clamp the restriction member 105, the spacer 104, the disk valve 103, the base valve member 76, the spring member 111, and the restriction member 112. Therefore, a clamping force can be accurately controlled relatively easily.Note that the second embodiment shown in FIG. 5 may use a pin member 98A having an external thread 141 formed on the shaft portion 99 and a nut 140 similar to those of the third embodiment shown in FIG. 6, instead of the pin member 98 having the enlarged diameter part 101 formed by deformation.In the foregoing first to third embodiments, the number of the protrusions 90 and that of the grooves 91 of the protrusion portion 84 of the base valve member 76 and the number of the tongue portions 116 of the disk valve 110 are each not limited to three as mentioned above, but may be not more than two or not more than four. However, the number of the protrusions 90, the grooves 91, and the tongue portions 116 is each preferably three from the viewpoint of achieving both stable opening and closing motion of the disk valve 110 and suitably forming the protrusions 90 and the grooves 91 by sintering.In addition, from the viewpoint of the operation of the disk valve 110, it is preferable that the positions of all the flow paths 94 in the circumferential direction of the disk valve 110 are arranged so as not to be aligned with the tongue portions 116 (i.e., the grooves 91). In other words, the flow paths 94 are aligned with the tongue portions 116 in the radial direction of the disk valve 110. Therefore, if the flow paths 94 are also aligned with the tongue portions 116 in the circumferential direction of the disk valve 110, the flow paths 94 inject the fluid to the tongue portions 116, which may have an influence on the operation of the disk valve 110. For this reason, it is preferable to arrange the flow paths 94 such that the positions of all the flow path recesses 92 are not aligned with the tongue portions 116 in the circumferential direction of the disk valve 110.It is also preferable to employ the above-described structure of the spool valve element 31 and the disk valve 55 of the spool 17. That is, the spacer 56 is omitted, but instead, the protrusion size of the protrusion portion 36 around the through hole 35 of the spool valve element 31 is increased, and the structure of the protrusion portion 84 is applied to the protrusion portion 36. Specifically, the protrusion portion 36 is locally provided with the circumferentially spaced grooves. In addition, the structure of the disk valve 110 is applied to the disk valve 55. That is, the tongue portions are formed on the inner peripheral side of the disk valve 55 such that the small diameter portions at the distal ends of the tongue portions slide relative to the attachment shaft portion 26 of the rod 22. It is also possible to apply the above-described structure to a valve externally installed on the cylinder 11.In the foregoing embodiments, the present invention has been applied to a cylinder device including a cylinder having a fluid sealed therein, a rod having an end extending out of the cylinder, flow paths through which the fluid flows as the rod moves, an annular valve element provided with at least a part of the flow paths and having a through hole, a pin member inserted through the through hole of the valve element, an annular disk valve having a pin member inserted therethrough and selectively movable away from contact and into contact with an end surface of the valve element at both inner and outer peripheries thereof to open and close the flow paths, respectively, and an enlarged diameter part, provided on the pin member at a position in front of the disk valve in a direction in which the disk valve is movable away from the one end surface of the valve member to prevent the disk valve from falling off. According to the present invention, the valve element has a protrusion portion around the through hole at the one end surface thereof. The protrusion portion is locally provided with circumferentially spaced grooves. The disk valve has small diameter projections extending from the inner periphery thereof to the grooves. The small diameter portions are slidable relative to the pin member. Thus, the protrusion portion of the valve element is provided with grooves, and the small diameter portions of the disk valve are guided to slide through the grooves by the pin member. Therefore, the trace of the disk valve becomes stable and stable valve characteristics can be obtained.The pin member is deformed at the distal end thereof to form an enlarged diameter part, and the deformation load is supported by the protrusion portion of the valve member. Thus, when the pin member is deformed to form the enlarged diameter part, the deformation load can be supported by the protrusion portion of the valve member. Therefore, it is not necessary to provide another component via the valve element to bear the deformation load, and thus it is possible to prevent the cost increase.In addition, since the enlarged diameter part is a nut threadedly engaged with the pin member, it is possible to facilitate accurate control of the installation condition of the constituting members.In addition, an annular restricting member that restricts movement of the disk valve away from an end surface of the valve element is clamped between the enlarged diameter part and the protruding portion. Because the annular restricting member that restricts movement of the disk valve away from the one end surface of the valve element can be clamped by the enlarged diameter part and the protrusion portion, it is not necessary to provide another component for clamping the restricting member, and thus it is possible to prevent the cost increase.In addition, the valve element is provided with an enlarged diameter portion facing the outer periphery of the protrusion portion. Thus, the outer periphery of the protrusion portion is extended so as to face the large diameter portion. Therefore, stable valve characteristics can be achieved even more effectively.In addition, because the outer diameter of the restriction member is larger than the diameter of a part of the disk valve corresponding to the small diameter portions but smaller than the diameter of the large diameter portion of the disk valve, the restriction member can be downsized. Therefore, it is possible to prevent the increase in cost and weight.According to the present invention, it is possible to obtain optimum valve characteristics.

Claims

A cylinder device comprising: a cylinder (11) having a fluid sealed therein; a rod (22) having an end extending out of the cylinder; flow paths (94, 95) through which the fluid flows as the rod (22) moves; an annular valve element (76) provided with at least a part of the flow paths and having a through hole (81); a pin member (98) inserted through the through hole (91) of the valve element (76); an annular disk valve (110) having the pin member (98) inserted therethrough, the disk valve being selectively movable away from and into contact with an end face of the valve element (76) on both inner and outer peripheries thereof to open and close the flow paths, respectively; and an enlarged diameter part (101, 140), which is provided on a portion of the pin member (98) in a direction in which the disk valve is movable away from the one end face of the valve member to prevent the disk valve from falling off, the valve member having a protrusion portion (84) around the through hole on the one end face, the protrusion portion (84) being locally provided with circumferentially spaced grooves (91), each of the grooves (91) extending radially through the protrusion portion (84) to the through hole, the disk valve (110) having small diameter portions (116) extending from an inner periphery to the grooves (91) thereof, the small diameter portions being slidable relative to the pin member (98), wherein, when the disk valve (110) is selectively moved at both the inner and outer peripheries thereof away from and in contact with an end surface of the valve element (76), the small diameter portions (116) move within the grooves (91), and the distal ends (117) of the small diameter portions (116) slide with respect to the pin member (98).The cylinder device according to claim 1, wherein the enlarged diameter part includes an enlarged diameter deformed portion formed by deforming a distal end of the pin member, wherein a deformation load is supported by the protrusion portion of the valve member.A cylinder device according to claim 1, wherein said enlarged diameter portion is a nut (140) threadedly engaging said pin member (98).The cylinder device according to any one of claims 1 to 3, further comprising: a restriction member (112) capable of restricting movement of the disk valve away from the one end surface of the valve element, wherein the restriction member is clamped between the enlarged diameter part (101, 140) and the protrusion portion (84).The cylinder device according to claim 4, wherein the valve element (110) is provided with a large-diameter portion (118) facing an outer periphery of the protrusion portion (84).The cylinder device according to claim 5, wherein the restriction member (112) has an outer diameter larger than a diameter of a part of the disk valve (110) corresponding to the small diameter portions (116) but smaller than a diameter of the large diameter portion (118).

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