Attenuation force adjusting type shock absorber

Abstract

To provide an attenuation force adjusting type shock absorber that allows stable attenuation force to be obtained.SOLUTION: A guide disc 161 is interposed between an outer diameter part 154 of a retainer 151 and a protruding part 149 of a core 99 of a solenoid 90 so that the core 99 of the solenoid 90 is not scraped by an edge of a passage part 157 formed in the retainer 151, and foreign matter (chips of the core 99) is not generated. Therefore, it is possible to eliminate a situation that the attenuation force varies due to the foreign matter clogging in the passage part 157 of the retainer 151 in the case of a failure, and the attenuation force of an attenuation force adjusting type shock absorber can be made stable.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a damping force adjustable shock absorber. [Background technology]

[0002] Patent Document 1 discloses a damping force adjustable shock absorber in which a solenoid case 94 and a cylindrical portion 8 of a piston bolt 5 are connected by screw fastening (hereinafter referred to as a "conventional damping force adjustable shock absorber"). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-0214436 Summary of the Invention [Problem to be solved by the invention]

[0004] In a conventional damping force adjustable shock absorber, when the solenoid case 94 and the piston bolt 5 are screwed together, the retainer 114 between the core 99 of the solenoid 91 and the head 7 of the piston bolt 5 rotates relative to the core 99 due to frictional forces generated at the contact surface, and the core 99 may be scraped off by the edge of a notch 120 (passage portion) formed in the retainer 114. If foreign matter (cuttings of the core 99) generated at this time gets stuck in the notch 120 of the retainer 114, the flow passage area of ​​the orifice due to the notch 120 becomes narrow, and there is a risk of the damping force varying in the event of a failure.

[0005] An object of the present invention is to provide a damping force adjustable shock absorber capable of obtaining a stable damping force. [Means for solving the problem]

[0006] The damping force control shock absorber of the present invention comprises an annular guide disk abutted against an annular protrusion formed on one axial end of a solenoid core and through which a valve member is inserted, a retainer whose outer diameter portion abuts against one axial end face of the guide disk, and a valve spring whose inner diameter portion abuts against a flange portion formed on the other axial end of the valve member and whose outer diameter portion is sandwiched, together with the outer diameter portions of the guide disk and the retainer, by the annular protrusion formed on the solenoid core and a bottom surface of an annular recess formed in the head of a piston bolt, wherein the guide disk has at least one notch formed in its outer diameter portion, the outer diameter portion abuts against the inner peripheral surface of the annular recess formed in the piston bolt, and the inner diameter is formed to be smaller than the inner diameter of the annular protrusion, and the retainer has a notch formed in its outer diameter portion and a passage portion extending radially inward from the notch. Effect of the Invention

[0007] According to the present invention, it is possible to provide a damping force adjustable shock absorber capable of obtaining a stable damping force. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view of an axial plane of a damping force control shock absorber according to an embodiment of the present invention; [Diagram 2] FIG. 2 is an enlarged view of a portion of FIG. [Diagram 3] FIG. 3 is an enlarged view of a main part in FIG. 2. [Figure 4] FIG. 2 is a plan view of a spring disc. [Diagram 5] FIG. [Figure 6] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described with reference to the accompanying drawings, in which: FIG. 1 shows a cross-sectional view along an axial plane of a damping force control shock absorber 1 according to this embodiment. Here, the damping force control shock absorber 1 is a piston-integrated type damping force control shock absorber in which a damping force generating mechanism 17 is incorporated in a cylinder 2.

[0010] As shown in FIG. 1, the damping force control shock absorber 1 has a twin-cylinder structure in which an outer cylinder 10 is provided on the outside of a cylinder 2. The damping force control shock absorber 1 has a piston mechanism section 44 including a piston 3 and a damping force generating mechanism 17. The piston 3 is inserted into the cylinder 2, and divides the inside of the cylinder 2 into two chambers, a first chamber 2A and a second chamber 2B. One axial end section 37 of a piston rod 36 is connected to the piston mechanism section 44. The other axial end section (not shown) of the piston rod 36 extends to the outside of the cylinder 2. The piston rod 36 is inserted through a rod guide 67 and an oil seal 69 that are attached to openings on the other axial end side of the cylinder 2 and the outer cylinder 10.

[0011] A reservoir 18 is formed between the cylinder 2 and the outer cylinder 10. The piston 3 has an extension-side passage 19 whose other axial end side (the "upper side" in FIG. 1) opens into the first chamber 2A, and a compression-side passage 20 whose one axial end side (the "lower side" in FIG. 1) opens into the second chamber 2B. A base valve 45 that separates the second chamber 2B from the reservoir 18 is provided at one axial end of the cylinder 2. The base valve 45 is provided with passages 46, 47 that communicate between the second chamber 2B and the reservoir 18.

[0012] A check valve 48 is provided in the passage 46 to allow the flow of oil (working fluid) from the reservoir 4 side to the second chamber 2B side. On the other hand, a disk valve 49 is provided in the passage 47, which opens when the pressure of the oil on the second chamber 2B side reaches a set pressure and releases the pressure (oil) on the second chamber 2B side to the reservoir 18 side. Note that oil is sealed in the cylinder 2 as the working fluid, and oil and gas are sealed in the reservoir 18. A bottom cap 50 is joined to one axial end of the outer cylinder 10.

[0013] The damping force generating mechanism 17 has a valve mechanism 28 and a solenoid 90. As shown in Fig. 2, the valve mechanism 28 has a piston bolt 5 whose shaft portion 6 is inserted into the shaft hole 4 of the piston 3, an extension-side valve mechanism 21 that controls the flow of working fluid in the extension-side passage 19, and a compression-side valve mechanism 51 that controls the flow of working fluid in the compression-side passage 20.

[0014] The extension side valve mechanism 21 has a cylindrical extension side pilot case 22 with a bottom, through which the shaft portion 6 of the piston bolt 5 is inserted. The extension side pilot case 22 has a bottom portion 27 and a cylindrical portion 26 that is open at the other axial end side (the "upper side" in FIG. 2). An extension side main valve 23 is disposed at the other axial end side of the extension side pilot case 22. An extension side back pressure chamber 25 is formed between the extension side main valve 23 and the extension side pilot case 22.

[0015] The extension side valve mechanism 21 has an annular seat portion 24 against which the extension side main valve 23 is seated and released. The seat portion 24 is formed on the outer periphery of the opening of the extension side passage 19 of the piston 3. The extension side back pressure chamber 25 is formed between the extension side pilot case 22 and the back surface of the extension side main valve 23. The pressure in the extension side back pressure chamber 25 acts on the extension side main valve 23 in the valve closing direction. An annular packing 31 made of an elastic body is baked on the extension side main valve 23. The extension side main valve 23 is a packing valve in which the packing 31 is in contact with the inner circumferential surface of the cylindrical portion 26 of the extension side pilot case 22 over the entire circumference.

[0016] The extension side back pressure chamber 25 is connected to the second chamber 2B via a passage 32 formed in the bottom 27 of the extension side pilot case 22 and a sub-valve 30. The sub-valve 30 opens when the pressure in the extension side back pressure chamber 25 reaches a predetermined pressure, and applies resistance to the flow of working fluid from the extension side back pressure chamber 25 to the second chamber 2B.

[0017] The extension side back pressure chamber 25 is connected to a first pressure receiving chamber 172 formed between the extension side pilot case 22 and the sub-valve 30 via a passage 32. The first pressure receiving chamber 172 is divided into a sector shape by a plurality of annular first seat portions 173 formed in the extension side pilot case 22. A passage 32 opens to the inside of each of the first seat portions 173.

[0018] The extension-side pilot case 22 has a back pressure introduction passage 171 through which the working fluid flows from the second chamber 2B to the extension-side back pressure chamber 25 when the piston 3 moves in the contraction direction (the "downward direction" in FIG. 2). The extension-side pilot case 22 has an annular seat portion 35 that defines a pressure receiving chamber 174.

[0019] A second pressure receiving chamber 177 isolated from the first pressure receiving chamber 172 is provided at one axial end of the extension side pilot case 22. The back pressure introduction passage 171 opens into the second pressure receiving chamber 177. The second pressure receiving chamber 177 is defined by a second seat portion 178. The second seat portion 178 extends in an arc shape between a pair of adjacent first pressure receiving chambers 172. A first orifice 175 that communicates between the second pressure receiving chamber 177 and the second chamber 2B is provided in the second seat portion 178.

[0020] As a result, an extension side communication passage that communicates the second chamber 2B and the extension side back pressure chamber 25 is formed in the extension side valve mechanism 21. When the piston 3 moves in the compression direction, the extension side communication passage introduces the working fluid in the second chamber 2B into the extension side back pressure chamber 25 via the first orifice 175, the second pressure receiving chamber 177, the back pressure introduction passage 171, the pressure receiving chamber 174, and the check valve 33.

[0021] On the other hand, the compression side valve mechanism 51 has a cylindrical compression side pilot case 52 with a bottom, through which the shaft portion 6 of the piston bolt 5 is inserted. The compression side pilot case 52 has a bottom portion 57 and a cylindrical portion 56 that is open at one axial end. A compression side main valve 53 is disposed at one axial end of the compression side pilot case 52. A compression side back pressure chamber 55 is formed between the compression side main valve 53 and the compression side pilot case 52.

[0022] The compression side valve mechanism 51 has an annular seat portion 54 against which the compression side main valve 53 is able to seat and unseat. The seat portion 54 is formed on the outer periphery of the opening of the compression side passage 20 of the piston 3. A compression side back pressure chamber 55 is formed between the compression side pilot case 52 and the back surface of the compression side main valve 53. The pressure in the compression side back pressure chamber 55 acts on the compression side main valve 53 in the valve closing direction. An annular packing 61 made of an elastic body is baked onto the compression side main valve 53. The compression side main valve 53 is a packing valve in which the packing 61 is in contact with the inner circumferential surface of the cylindrical portion 56 of the compression side pilot case 52 over the entire circumference.

[0023] The compression back pressure chamber 55 is connected to the first chamber 2A via a passage 62 formed in a bottom 57 of the compression pilot case 52 and a sub-valve 60. The sub-valve 60 opens when the pressure in the compression back pressure chamber 55 reaches a predetermined pressure, and applies resistance to the flow of working fluid from the compression back pressure chamber 55 to the first chamber 2A.

[0024] The compression back pressure chamber 55 is connected by a passage 62 to a first pressure receiving chamber 182 formed between the compression pilot case 52 and the sub-valve 60. The first pressure receiving chamber 182 is divided into a sector shape by a plurality of first seat portions 183 provided in the compression pilot case 52. A passage 62 opens to the inside of each of the first seat portions 183.

[0025] The compression side pilot case 52 has a back pressure introduction passage 181 through which a flow of working fluid occurs from the first chamber 2A to the compression side back pressure chamber 55 when the piston 3 moves in the extension direction (the "upward direction" in FIG. 2). The compression side pilot case 52 has an annular seat portion 65 that defines a pressure receiving chamber 184.

[0026] A second pressure receiving chamber 187 isolated from the first pressure receiving chamber 182 is provided on the other axial end side of the compression side pilot case 52. The back pressure introduction passage 181 opens into the second pressure receiving chamber 187. The second pressure receiving chamber 187 is defined by a second seat portion 188. The second seat portion 188 extends in an arc shape between the pair of adjacent first pressure receiving chambers 182. A first orifice 185 that communicates between the second pressure receiving chamber 187 and the first chamber 2A is provided in the second seat portion 188.

[0027] As a result, a compression side communicating passage that communicates between the first chamber 2A and the compression side back pressure chamber 55 is formed in the compression side valve mechanism 51. When the piston 3 moves in the extension direction, the compression side communicating passage introduces the working fluid from the first chamber 2A into the compression side back pressure chamber 55 via the first orifice 185, the second pressure receiving chamber 187, the back pressure introduction passage 181, the pressure receiving chamber 184, and the check valve 63. By tightening a nut 78 attached to a threaded portion (reference number omitted) of the shaft portion 6 of the piston bolt 5, an axial force is generated in the valve parts that constitute the extension side valve mechanism 21 and the compression side valve mechanism 51.

[0028] A common passage 11 is formed in the piston bolt 5. The common passage 11 has an axial passage 12 formed inside (axial hole) of a sleeve 15. The sleeve 15 is press-fitted into a hole 16 whose other axial end side (the "upper side" in FIG. 2) opens into the head 7 of the piston bolt 5. The common passage 11 has an axial passage 13 formed on one axial end side of the hole 16. The common passage 11 has an axial passage 14 consisting of a small diameter hole whose other axial end side opens into the hole 16. The inner diameter of the common passage 11 is largest for the axial passage 13, followed by the axial passage 12 and the axial passage 14 in that order. The axial passage 12 opens into the end face 9 of the head 7 of the piston bolt 5.

[0029] The extension-side back pressure chamber 25 communicates with a radial passage 34 formed in the shaft portion 6 of the piston bolt 5 through an orifice (reference number omitted) formed in the seat portion 35 of the extension-side pilot case 22 and a pressure-receiving chamber 174. The radial passage 34 communicates with an axial passage 14. The axial passage 14 communicates with a radial passage 39 formed in the shaft portion 6 of the piston bolt 5.

[0030] The radial passage 39 is connected to the extension-side passage 19 via an annular passage 41 formed in the piston 3, a plurality of notches 42 formed in the inner diameter portion of the piston 3, and a disk valve 40 provided in the piston 3. The disk valve 40 is seated and releasably abutted against an annular seat portion 43 formed on the inner diameter side of the piston 3 relative to the seat portion 24 and the opening of the extension-side passage 19. The disk valve 40 is a check valve that allows the flow of working fluid from the radial passage 39 to the extension-side passage 19.

[0031] The compression side back pressure chamber 55 communicates with a radial passage 64 formed in the shaft portion 6 of the piston bolt 5 through an orifice (reference number omitted) formed in the seat portion 65 of the compression side pilot case 52, the pressure receiving chamber 184, an annular passage 68 formed in the inner diameter portion of the bottom portion 57 of the compression side pilot case 52, and a two-face width portion 77 formed in the shaft portion 6 of the piston bolt 5. The radial passage 64 communicates with the axial passage 12 through a hole 66 formed in the side wall of the sleeve 15.

[0032] The radial passage 64 is connected to the compression side passage 20 via the two-face width portion 77, an annular passage 71 formed at the other axial end of the shaft hole 4 of the piston 3, a plurality of notches 72 formed in the inner diameter portion of the piston 3, and a disk valve 70 formed in the piston 3. The disk valve 70 is in releasable contact with an annular seat portion 73 provided on the inner diameter portion side of the seat portion 54 and the opening of the compression side passage 20 of the piston 3. The disk valve 70 is a check valve that allows the flow of working fluid from the radial passage 64 to the compression side passage 20.

[0033] The flow of working fluid in the common passage 11 is controlled by a pilot valve 81. The pilot valve 81 has a valve spool 82 (valve member) slidably provided in the common passage 11, and a seat portion 83 formed on the periphery of the opening of the axial passage 14 at the bottom of the hole 16. The valve spool 82 is made of a solid shaft, and has a sliding portion 84 inserted into the sleeve 15, and a valve body 85 abutting against the seat portion 83 so as to be able to seat and separate from the seat.

[0034] The valve spool 82 has a head 87 formed on the other axial end side of the sliding portion 84. A first chamber 130 is formed on the outer periphery of the head 87. A flange portion 88 is formed at one axial end side of the head 87. A spring disc 140 (valve spring) that urges the valve spool 82 in the valve opening direction of the pilot valve 81 (the "upward direction" in FIG. 2) is in contact with an end face on the one axial end side of the flange portion 88.

[0035] A cylindrical cap 121 with a bottom that is open on the other axial end side is attached to the head 7 of the piston bolt 5. The gap between the cap 121 and the head 7 of the piston bolt 5 is sealed by an annular seal member 128 (O-ring). This defines an annular second chamber 131 between the cap 121 and the head 7 of the piston bolt 5. An insertion hole 123 is formed in the cap 121, through which the shaft portion 6 of the piston bolt 5 is inserted. A plurality of notches 124 (shown as "two" in FIG. 2) are provided on the outer periphery of the insertion hole 123. The notches 124 are connected to the two-face width portion 77 formed in the shaft portion 6.

[0036] Between the cap 121 and the head 7 of the piston bolt 5, a spool backpressure relief valve 107, a spacer 108, and a retainer 132 are provided, in this order from the head 7 side. The spool backpressure relief valve 107, the spacer 108, and the retainer 132 are provided in a second chamber 131. The spool backpressure relief valve 107 is a check valve that allows the flow of working fluid from the first chamber 130 to the second chamber 131 via a passage 29 formed in the head 7 of the piston bolt 5.

[0037] The outer diameter portion of the spool back pressure relief valve 107 is in movable contact with an annular seat portion 109 formed on the head 7 of the piston bolt 5. The inner diameter portion of the retainer 132 is provided with a plurality of notches 133 that communicate the second chamber 131 with the two-face width portion 77 and the notch 124 of the cap 121. A retainer 59 that determines the maximum valve opening amount of the sub valve 60 is interposed between the cap 121 and the sub valve 60. A fail-safe valve 111 is configured in the first chamber 130. The fail-safe valve 111 has a flange portion 88 (valve body) of the head 87 of the valve spool 82, and a seat portion 112 (valve seat) formed on an end face on one axial end side of the core 99 of the solenoid 90.

[0038] A two-face width notch 86 is formed in the valve body 85 of the valve spool 82. When the control current passed through the coil 95 of the solenoid 90 is 0 A (at the time of failure), the valve spool 82 moves toward the other axial end side (upward in FIG. 2) by the urging of the spring disc 140, and the valve body 85 fits into the axial passage 12. As a result, a pair of orifices 114 (only one is shown in FIG. 2) that communicate between the axial passages 12, 13 are formed between the valve body 85 and the axial passage 12. Note that only one of the pair of faces that form the two-face width (notch 86) may be formed. In this case, there will be only one orifice 114.

[0039] On the other hand, when the coil 95 is energized and the valve element 85 of the valve spool 82 seats on the seat portion 83, the pilot valve 81 is closed. The valve opening pressure of the pilot valve 81 can be adjusted by controlling the energization of the coil 95. In the soft mode in which the current value of the control current is small, the biasing force of the spring disc 140 and the thrust generated by the plunger 96 are balanced, and the valve element 85 is separated from the seat portion 83 by a certain distance.

[0040] The solenoid 90 has a solenoid mechanism 91, a solenoid case 191, and a coil 95 housed in the solenoid case 191. The solenoid mechanism 91 has an actuation rod 92, a plunger 96 fixed to the outer periphery of the actuation rod 92, and cores 98, 99 divided into upper and lower halves. The actuation rod 92 is guided in the axial direction (the "up and down direction" in FIG. 2) by a bush 100 attached to a core lid 106 and a bush 110 attached to the core 99. An internal rod passage 97 is formed inside the actuation rod 92, which is in communication with a rod back pressure chamber 103 formed inside the core lid 106.

[0041] A seal member 116 seals the gap between one axial end of the bottomed cylindrical solenoid case 191 and the core 99. As a result, an annular passage 117 is formed between the piston bolt 5, the solenoid case 191, and the core 99. The annular passage 117 is connected to the first chamber 2A by a passage 118 that penetrates in the radial direction (the "left-right direction" in FIG. 2) a cylindrical portion 8 formed on the other axial end side (the "upper side" in FIG. 2) of the head 7 of the piston bolt 5. A spool back pressure chamber 101 is formed between the core 99 and the head 87 of the valve spool 82. The spool back pressure chamber 101 is connected to the rod back pressure chamber 103 via a notch (not shown) formed in the operating rod 92 and the rod inner passage 97.

[0042] One axial end 37 of the piston rod 36 is joined to the bottom 192 of the solenoid case 191 by plastic flow. One axial end of the solenoid case 191 and the cylindrical portion 8 of the piston bolt 5 are connected by screw fastening. As a result, one axial end 37 of the piston rod 36 is connected to the piston 3 via the solenoid case 191 and the piston bolt 5. Note that, in addition to the above-mentioned joining by plastic flow, the method of fixing the bottom 192 of the solenoid case 191 to one axial end 37 of the piston rod 36 can be screw fastening, welding, or the like.

[0043] The flow of hydraulic oil in the above-mentioned damping force control shock absorber 1 will be described. During the extension stroke, the working fluid in the first chamber 2A is introduced into the extension backpressure chamber 25 via the upstream backpressure introduction passage, i.e., the extension passage 19, the orifice (symbol omitted) formed in the disc valve 40, the notch 42 and the annular passage 41 formed in the piston 3, the radial passage 34, the axial passage 14, the radial passage 39, the annular passage 38 formed in the extension pilot case 22, and the check valve 33.

[0044] During the extension stroke, the working fluid in the first chamber 2A is introduced into the compression backpressure chamber 55 via the compression communication passage, i.e., the first orifice 185, the second pressure receiving chamber 187, the backpressure introduction passage 181, and the check valve 63. This prevents the compression main valve 53 from opening due to the pressure in the first chamber 2A during the extension stroke.

[0045] During the extension stroke, the working fluid introduced into the compression back pressure chamber 55 flows through the orifice (symbol omitted) formed in the seat portion 65, the pressure receiving chamber 184, the annular passage 68 formed in the compression pilot case 52, the two-face width portion 77 formed in the shaft portion 6 of the piston bolt 5, the notch 72 formed in the piston 3, the disc valve 70, and the compression side passage 20 to the second chamber 2B (the downstream chamber). Therefore, before the extension main valve 23 opens, that is, in the low piston speed region, a damping force due to the orifice characteristics of the orifice 67 formed in the seat portion 65 and the valve characteristics of the disc 70 is obtained.

[0046] On the other hand, during the compression stroke, the working fluid in the second chamber 2B is introduced into the compression back pressure chamber 55 via the upstream back pressure introduction passage, i.e., the compression passage 20, the orifice (symbol omitted) formed in the disc valve 70, the notch 72 formed in the piston 3, the annular passage 71 formed in the axial hole 4 of the piston 3, the two-face width portion 77 formed in the shank 6 of the piston bolt 5, the annular passage 68 formed in the compression pilot case 52, and the check valve 63.

[0047] During the compression stroke, the working fluid in the second chamber 2B is introduced into the extension backpressure chamber 25 via the extension communication passage, i.e., the first orifice 175, the second pressure receiving chamber 177, the backpressure introduction passage 171, and the check valve 33. This prevents the extension main valve 23 from opening due to the pressure in the second chamber 2B during the compression stroke.

[0048] During the compression stroke, the working fluid introduced into the extension-side back pressure chamber 25 flows through the orifice (reference number omitted) formed in the seat portion 35, the pressure-receiving chamber 174, the annular passage 38 formed in the inner periphery of the bottom 27 of the extension-side pilot case 22, the radial passage 39, the axial passage 14, the radial passage 34, the annular passage 41 and the notch 42 formed in the piston 3, the disc valve 40, and the extension-side passage 19 to the first chamber 2A. Therefore, before the compression-side main valve 53 opens, that is, in the low-speed region of the piston speed, a damping force due to the orifice characteristics of the orifice formed in the seat portion 35 and the valve characteristics of the disc 40 is obtained.

[0049] Next, the main parts of this embodiment will be described. As shown in Figure 3, an annular recess 146 is formed on the other axial end side of head 7 of piston bolt 5 (the "upper side" in Figure 3). A surface 141 on one axial end side (the "lower side" in Figure 3) of outer diameter portion 143 (see Figure 4) of spring disc 140 abuts against a bottom surface 147 of annular recess 146. An inner diameter portion 144 (see Figure 4) of spring disc 140 abuts against a surface 89 on one axial end side of flange portion 88 formed on head 87 (the other axial end portion of the valve member) of valve spool 82.

[0050] A surface 152 at one axial end of a retainer 151 abuts against a surface 142 at the other axial end of an outer diameter portion 143 of the spring disc 140. A surface 162 at one axial end of a guide disc 161 abuts against a surface 153 at the other axial end of an outer diameter portion 154 (see FIG. 5 ) of the retainer 151. A surface 163 at the other axial end of the guide disc 161 abuts against an annular protrusion 149 formed on the outer circumferential edge portion at one axial end of a core 99 of the solenoid 90.

[0051] The outer diameter portion 143 of the spring disc 140, the outer diameter portion 154 of the retainer 151, and the guide disc 161 are sandwiched between a bottom surface 147 of an annular recess 146 of the piston bolt 5 and an annular protrusion 149 of the core 99 of the solenoid 90. The force that sandwiches the spring disc 140, the retainer 151, and the guide disc 161 is obtained by an axial force that is generated by screwing together the solenoid case 191 and the cylindrical portion 8 of the piston bolt 5.

[0052] The valve spool 82 (valve member) is inserted into the inside of the inner diameter portion 155 of the retainer 151. The outer diameter portion 154 of the retainer 151 is abutted against the inner side surface 148 (inner peripheral surface) of the annular recess 146 of the piston bolt 5. The inner diameter of the retainer 151 is larger than the outer diameter of the flange portion 88 of the valve spool 82. As shown in FIG. 5, the retainer 151 has a notch portion 156 formed by cutting out a part of the outer diameter portion 154 in a D shape. The retainer 151 has a slit-shaped passage portion 157 whose one end is open at the center in the width direction (the "vertical direction" in FIG. 5) of the notch portion 156 and whose other end side (the "left side" in FIG. 5) extends radially inward. The passage portion 157 forms a passage (orifice) that communicates between the first chamber 130 and the annular passage 117.

[0053] The valve spool 82 (valve member) is inserted into the inside of the inner diameter portion 165 of the guide disc 161. The outer diameter portion 164 of the guide disc 161 abuts against the inner side surface 148 (inner circumferential surface) of the annular recess 146 of the piston bolt 5. In other words, the outer diameter of the guide disc 161 is equal to the outer diameter of the retainer 151. The inner diameter of the guide disc 161 is larger than the inner diameter of the retainer 151 and is smaller than the inner diameter of the annular protrusion 149 of the core 99 of the solenoid 90.

[0054] 6, the guide disc 161 has a plurality of ("12" in this embodiment) notches 166 formed by cutting out the outer diameter portion 164 in a concave shape. The plurality of notches 166 are arranged at intervals L1 in the tangential direction of the guide disc 161. The width L2 (tangential length) of the notches 166 is set to be larger than the interval L1 between the notches 166, 166 (L2>L1).

[0055] The guide disc 161 has an inner diameter larger than the inner diameter of the retainer 151, and the inner diameter is set larger than the distance L5 from the center of the retainer 151 to the passage portion 157. The distance L3 from the center of the guide disc 161 to the notch 166 is set equal to the distance L4 from the center of the retainer 151 to the notch portion 156 (L3=L4). Note that the guide disc 161 is made of a material having the same hardness as or greater than the material of the retainer 151 (the "same material" in this embodiment).

[0056] When the control current to coil 95 of solenoid 90 fails at 0A, the first chamber 2A and second chamber 2B of cylinder 10 are connected via first chamber 130, passage portion 157 (orifice) formed in retainer 151, notch 166 formed in guide disc 161, annular passage 117, and passage 118 formed in cylindrical portion 8 of piston bolt 5, so that a damping force with orifice characteristics can be obtained by passage portion 157.

[0057] In a conventional damping force adjustable shock absorber, when the solenoid case and the piston bolt are screwed together, the retainer between the core of the solenoid and the head of the piston bolt rotates relative to the core due to frictional forces generated on the contact surface, and the core is sometimes scraped by the edge of the passage (notch) formed in the retainer. If foreign matter (chips from the core) generated at this time gets clogged in the passage of the retainer, the flow area of ​​the orifice by the passage becomes narrow, and there is a risk of variation in the damping force in the event of a failure.

[0058] In contrast, in this embodiment, a guide disk 161 is interposed between the outer diameter portion 154 of the retainer 151 and the protruding portion 149 of the core 99 of the solenoid 90, so that the core 99 of the solenoid 90 is not scraped off by the edge of the passage portion 157 formed in the retainer 151. Therefore, since foreign matter (cuttings of the core 99) is not generated as in the conventional damping force adjustable shock absorber, it is possible to eliminate the situation in which the damping force varies during failure due to the foreign matter clogging the passage portion 157 of the retainer 151. In this embodiment, the guide disc 161 is made of a material having a hardness equal to or greater than that of the retainer 151, thereby making it possible to avoid the generation of foreign matter caused by the guide disc 161 being scraped by the edge of the passage portion 157 of the retainer 151. [Explanation of symbols]

[0059] 1 adjustable damping shock absorber, 2 cylinder, 2A first chamber, 2B second chamber, 3 piston, 5 piston bolt, 6 shaft portion, 7 head, 8 cylindrical portion, 11 common passage, 36 piston rod, 82 valve spool (valve member), 88 flange portion, 90 solenoid, 95 coil, 99 core, 140 spring disc (valve spring), 143 inner diameter portion, 144 inner diameter portion, 146 annular recess, 149 annular protrusion portion, 151 retainer, 154 outer diameter portion, 155 inner diameter portion, 156 cutout portion, 157 passage portion, 161 guide disc, 164 outer diameter portion, 165 inner diameter portion, 166 cutout portion

Claims

1. A cylinder in which a working fluid is sealed; a piston rod having one axial end inserted into the cylinder and the other axial end protruding from the cylinder to the outside; a solenoid case connected to one axial end of the piston rod, accommodating a solenoid coil therein, and covering at least a portion of a solenoid core; a piston bolt having a head portion having a cylindrical portion that is fixed to one axial end portion of the solenoid case by screw fastening, and a shaft portion that extends from the head portion toward the one axial end side; a piston into which a shaft portion of the piston bolt is inserted and which divides the inside of the cylinder into a first chamber and a second chamber; a valve member that is inserted into a common passage formed in the piston bolt and that is movable in an axial direction when a current is applied to a coil of the solenoid; an annular guide disk that is in contact with an annular protrusion formed on one axial end of the solenoid core and through which the valve member is inserted; a retainer having an outer diameter portion abutting against one axial end surface of the guide disk; a valve spring having an inner diameter portion abutting a flange portion formed on the other axial end portion of the valve member, and an outer diameter portion being sandwiched by the guide disk and the outer diameter portion of the retainer, the annular protrusion formed on the core of the solenoid, and a bottom surface of an annular recess formed in the head of the piston bolt, The guide disk has at least one notch formed in an outer diameter portion, the outer diameter portion abutting against an inner circumferential surface of an annular recess formed in the piston bolt, and an inner diameter formed smaller than an inner diameter of the annular protrusion, A damping force control shock absorber, wherein the retainer has a notch portion formed in an outer diameter portion, and a passage portion extending radially inward from the notch portion.

2. 2. The damping force control shock absorber according to claim 1, A damping force adjustable shock absorber, wherein a distance from a center of the retainer to a notch of the retainer is equal to a distance from a center of the guide disc to the notch of the guide disc.

3. 2. The damping force control shock absorber according to claim 1, a retainer having an outer diameter portion abutting against the inner peripheral surface of the annular recess of the piston bolt, an inner diameter smaller than the inner diameter of the guide disc, and an inner diameter larger than the outer diameter of the flange portion of the valve member;

4. 2. The damping force control shock absorber according to claim 1, A damping force adjustable shock absorber characterized in that a plurality of the cutout portions are formed in the guide disc at regular intervals in the circumferential direction, and the width of the cutout portions formed in the guide disc is greater than the distance between adjacent cutout portions.

5. 2. The damping force control shock absorber according to claim 1, A damping force control shock absorber, wherein the guide disk is made of the same material as the retainer or a material harder than the retainer.

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