Damping force adjustment-type shock absorber
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2026-01-28
- Publication Date
- 2026-08-13
Smart Images
Figure JP2026002747_13082026_PF_FP_ABST
Abstract
Description
Damping force adjustable shock absorber
[0001] The present invention relates to a shock absorber that controls the flow of working fluid with respect to the stroke of a piston rod to adjust the damping force.
[0002] Patent Document 1 discloses a damping force adjustable shock absorber 1 (hereinafter referred to as "conventional damping force adjustable shock absorber") in which a cylinder 2 incorporates a damping force adjustment mechanism that controls the flow of working fluid in a common passage 11 formed in a piston bolt 5 by a pilot valve 81.
[0003] Japanese Patent Application Laid-Open No. 2022-36582
[0004] In the conventional damping force adjustable shock absorber, since there is no passage for removing air mixed in the working oil from the solenoid chamber during the assembly of the solenoid valve, the air bleeding performance (hereinafter referred to as "air bleeding property") of the air remaining in the solenoid chamber is low.
[0005] An object of the present invention is to provide a damping force adjustable shock absorber with improved air bleeding property of the solenoid chamber.
[0006] The damping force adjustable shock absorber of the present invention comprises a solenoid valve comprising: a cylindrical case member; a coil housed in the case member; a movable iron core positioned radially inward of the coil; a shaft member fixed to the movable iron core, with the valve body fixed to one end of the shaft member on its axial side; a housing covering the other axial end of the shaft member between the movable iron core and the shaft member; a partition member fixed to the housing and partitioning the inside of the housing; and a gas chamber formed between the housing and the partition member, in which gas can be retained. Furthermore, the damping force adjustable shock absorber of the present invention comprises a cylinder in which a working fluid is sealed; a rod in which one axial end is inserted into the cylinder and the other axial end protrudes outward from the cylinder; a piston connected to the axial end of the rod and partitioning the inside of the cylinder; a passage through which the working fluid flows as the piston moves; a valve body that controls the flow rate of the working fluid flowing through the passage; a shaft member on which the valve body is provided at one axial end; a movable core fixed to the shaft member; and a solenoid valve equipped with a coil for driving the movable core; a case member that houses the solenoid valve; a housing provided inside the case member and arranged to cover the shaft member or the movable core; and a partitioning member provided inside the housing and arranged closer to the vehicle body than the shaft member or the movable core, partitioning the inside of the housing and formed to allow gas to pass through.
[0007] According to one embodiment of the present invention, the variable range of damping force of a damping force adjustable shock absorber can be extended.
[0008] This figure shows a cross-sectional view of a part of the damping force adjustable shock absorber according to this embodiment. This figure shows an enlarged view of one axial end side in Figure 1. This figure shows an enlarged view of the other axial end side in Figure 1. This is an explanatory diagram of the variable orifice in this embodiment. This is an explanatory diagram of the main parts (partition member, air chamber) in this embodiment. This is an explanatory diagram of another embodiment, which is an explanatory diagram of the damping force adjustment mechanism in a damping force adjustable hydraulic shock absorber with a control valve mounted next to it.
[0009] One embodiment of the present invention will be described with reference to the attached figures. In this embodiment, a single-tube type damping force adjustable shock absorber is described as an example, but the damping force adjustable shock absorber according to this embodiment is also applicable to a double-tube type damping force adjustable shock absorber having a reservoir. For convenience, the lower side in Figure 1 will be referred to as the "axial end side," and the upper side in Figure 1 will be referred to as the "axial other end side."
[0010] As shown in Figure 1, the damping force adjustable shock absorber 1 includes a cylinder 2 filled with working fluid and a piston 3 slidably fitted inside the cylinder 2, which divides the inside of the cylinder 2 into a first chamber 2A and a second chamber 2B. The piston 3 has a compression-side passage 4 that opens to the second chamber 2B at one axial end and an extension-side passage 5 that opens to the first chamber 2A at the other axial end. A free piston (not shown) that can move vertically inside the cylinder 2 is fitted inside the cylinder 2 at one axial end of the piston 3. The free piston divides the inside of the cylinder 2 into a second chamber 2B at the other axial end and a gas chamber (not shown) at one axial end.
[0011] The damping force adjustable shock absorber 1 includes a piston rod 6, one end of which is inserted into the cylinder 2 in the axial direction and the other end of which extends outward from the cylinder 2 in the axial direction, and a piston bolt 11 connected to the piston rod 6 via the solenoid case 121 (case member) of the solenoid valve 120. The piston bolt 11 has a bottomed cylindrical head 12 and a shaft portion 15 that extends from the center of the head 12 toward one end in the axial direction and is inserted into the axial hole 9 of the piston 3. The piston bolt 11 is formed by joining the head 12 and the shaft portion 15 by press-fitting. The solenoid case 121 is fastened to the end 7 on one end in the axial direction of the piston rod 6 by tightening a lock nut 8 attached to the piston rod fastening portion 122.
[0012] The damping force adjustable shock absorber 1 has a damping force adjustment mechanism that adjusts the damping force characteristics by controlling the flow of working fluid accompanying the movement of the piston 3. The damping force adjustment mechanism has a valve mechanism 10 and a solenoid valve 120. The valve mechanism 10 has a compression-side valve mechanism 41 that controls the flow of working fluid in the compression-side passage 4 and an extension-side valve mechanism 61 that controls the flow of working fluid in the extension-side passage 5.
[0013] As shown in Figure 2, the compression valve mechanism 41 includes a bottomed cylindrical pilot case 42, a compression main valve 43 provided on the piston 3 side (the "lower side" in Figure 2) of the pilot case 42, and a compression back pressure chamber 44 formed between the pilot case 42 and the back surface of the compression main valve 43. The compression valve mechanism 41 has a seat portion 45 formed on the outer circumference of the end face on the other axial end of the piston 3, with which the compression main valve 43 abuts so as to be able to seat and dissipate. The pressure in the compression back pressure chamber 44 acts on the compression main valve 43 in the closing direction. The compression main valve 43 is a packing valve in which an annular packing 46 made of an elastic material contacts the inner circumferential surface of the pilot case 42 around its entire circumference.
[0014] The compression-side back pressure chamber 44 is connected to the first chamber 2A via a passage 47 formed in the pilot case 42 and a sub-valve 48. The sub-valve 48 opens when the pressure in the compression-side back pressure chamber 44 reaches a predetermined pressure, providing resistance to the flow of working fluid from the compression-side back pressure chamber 44 to the first chamber 2A. The compression-side back pressure chamber 44 is connected to the first pressure-receiving chamber 49 formed between the pilot case 42 and the sub-valve 48 via the passage 47 formed in the pilot case 42. The first pressure-receiving chamber 49 is defined by a first seat portion 50 formed on the outer circumference of the end face on the other axial end of the pilot case 42, and the other axial end of the passage 47 is open.
[0015] As shown in Figure 2, the extension valve mechanism 61 includes a bottomed cylindrical pilot case 62, an extension main valve 63 provided on the piston 3 side (the "upper side" in Figure 2) of the pilot case 62, and an extension back pressure chamber 64 formed between the pilot case 62 and the back surface of the extension main valve 63. The extension valve mechanism 61 has a seat portion 65 formed on the outer circumference of the end face on one axial end of the piston 3, with which the extension main valve 63 abuts so as to be able to seat and dissipate. The pressure in the extension back pressure chamber 64 acts on the extension main valve 63 in the closing direction. The extension main valve 63 is a packing valve in which an annular packing 66 made of an elastic material contacts the inner circumferential surface of the pilot case 62 around its entire circumference.
[0016] The extension-side back pressure chamber 64 is connected to the second chamber 2B via a passage 67 formed in the pilot case 62 and a sub-valve 68. The sub-valve 68 opens when the pressure in the extension-side back pressure chamber 64 reaches a predetermined pressure, providing resistance to the flow of working fluid from the extension-side back pressure chamber 64 to the second chamber 2B. The extension-side back pressure chamber 64 is connected to the first pressure-receiving chamber 69 formed between the pilot case 62 and the sub-valve 68 via the passage 67 formed in the pilot case 62. The first pressure-receiving chamber 69 is defined by a first seat portion 70 formed on the outer circumference of the end face on one axial end of the pilot case 62, and the axial end of the passage 67 is open.
[0017] Furthermore, by tightening the nut 16 screwed onto the axial end of the shaft portion 15 of the piston bolt 11, an axial force is generated in the valve components constituting the compression-side valve mechanism 41 and the extension-side valve mechanism 61.
[0018] As shown in Figure 2, the piston bolt 11 has a spool hole 18 formed in the shaft portion 15 and a sleeve 19 that is press-fitted into the spool hole 18. A common passage 20 is formed in the piston bolt 11. The common passage 20 has an axial passage 21 formed in the sleeve 19, an axial passage 22 formed in the spool hole 18 on one axial end side of the sleeve 19, and an axial passage 23 whose other axial end opens into the axial passage 22. The inner diameter of the common passage 20 decreases in the order of axial passage 22, axial passage 21, and axial passage 23.
[0019] The compression-side back pressure chamber 44 is connected to the compression-side passage 4 via a notch 52 formed in the disk 51, an annular passage 24 formed between the pilot case 42 and the shaft portion 15 of the piston bolt 11, a notch 25 formed in the shaft portion 15 of the piston bolt 11, a radial passage (not shown) formed in the spacer 54, and the disk 53. On the other hand, the extension-side back pressure chamber 64 is connected to the extension-side passage 5 via a notch 72 formed in the disk 71, an annular passage 26, a radial passage 27, an axial passage 23, a radial passage 28, an annular passage 30, a radial passage (not shown) formed in the spacer 74, and the disk 73.
[0020] The flow of working fluid in the common passage 20 is controlled by a pilot valve 101. The pilot valve 101 has a spool 102 made of a solid shaft and supported by a sleeve 19 so as to be movable in the axial direction. The spool 102 has a head 103 formed at the other axial end, a sliding portion 104 that is slidably fitted inside the sleeve 19, a valve body 105 formed at the one axial end, and a connecting portion 106 formed between the valve body 105 and the sliding portion 104.
[0021] The pilot valve 101 has a first valve seat 107 formed on the peripheral edge (opening) of one axial end of the axial passage 21, and a first valve portion 108 formed on the peripheral edge of the other axial end of the valve body 105. When the coil 125 of the solenoid valve 120 is not energized (see Figure 2), the pilot valve 101 restricts the flow of working fluid in the common passage 20 by the first valve portion 108 seating (fitting) with the first valve seat 107. The pilot valve 101 has a second valve seat 109 formed on the peripheral edge (opening) of the other axial end of the axial passage 23, and a second valve portion 110 formed on the peripheral edge of the end face of one axial end of the valve body 105. When the coil 125 of the solenoid valve 120 is energized, the pilot valve 101 restricts the flow of working fluid in the common passage 20 by the second valve portion 110 seating with the second valve seat 109.
[0022] A first chamber 111 is formed between the head 12 of the piston bolt 11 and the core 150 of the solenoid valve 120, defined by a recess 193 formed on the end face of the bottom 13 of the piston bolt 11 on the other axial end. An outer flange-type spring receiver 112 is formed on the head 103 of the spool 102. The inner circumference of a spring disc 141, which biases the spool 102 in the opening direction of the second valve section 110 (upward in Figure 2), is connected to the spring receiver 112.
[0023] When the coil 125 of the solenoid valve 120 is not energized (see Figure 2), the head 103 of the spool 102 is pressed against (pressed against) the end face of the axial end of the operating rod 127 of the solenoid valve 120 by the biasing force of the spring disc 141. A spool back pressure chamber 136 is formed in the center of the axial end of the core 150 of the solenoid valve 120. The spool back pressure chamber 136 is connected to a rod back pressure chamber 138 (see Figure 3) via a notch 137 formed in the operating rod 127 and an internal rod passage 129 of the operating rod 127.
[0024] When the control current to the coil 125 of the solenoid valve 120 is 0A (fail), the biasing force of the spring disc 141 moves the spool 102 in the opening direction of the pilot valve 101, and the first valve portion 108 of the valve body 105 seats (fits) onto the first valve seat 107. As a result, an orifice (not shown) is formed between the valve body 105 and the sleeve 19 (axial passage 21), connecting the axial passage 21 and the axial passage 22.
[0025] As shown in Figure 2, a bottomed cylindrical cap 31, with an opening at the other axial end, is fitted around the outer circumference of the head 12 of the piston bolt 11. The space between the cap 31 and the head 12 of the piston bolt 11 is sealed by an O-ring 39. This forms an annular second chamber 114 between the cap 31 and the piston bolt 11. The cap 31 has a through hole 32 through which the shaft portion 15 of the piston bolt 11 is inserted. The cap 31 has a notch 33 formed in the through hole 32. The notch 33 communicates with a passage 24 formed between the pilot case 42 and the shaft portion 15 of the piston bolt 11.
[0026] The second chamber 114 is provided with a check valve 35 (spool back pressure relief valve) that allows the working fluid to flow from the first chamber 111 to the second chamber 114 via the passage 34. The outer peripheral edge of the check valve 35 abuts against an annular seat portion 36 formed on the end face of the axial end of the head 12 of the piston bolt 11 in a manner that allows it to seat and detach. The inner circumference of the retainer 37 that restricts the opening of the check valve 35 has multiple notches 38 (only "two" are shown in Figure 2) that connect the second chamber 114 to the compression side back pressure chamber 44 via notches 33, 25, 24, and 52 formed in the disk 51.
[0027] As shown in Figure 3, the solenoid valve 120 has a solenoid case 121, a coil 125, a core 148, a core 150, an operating rod 127, and a movable iron core 130 fixed to the outer circumference of the operating rod 127. The operating rod 127 is guided axially by a bush 132 installed in a partition member 81 (described later) and a bush 133 installed in the core 150. The solenoid case 121 is fastened to the piston bolt 11 by a screw fastening portion 124 formed between the axial end of the cylindrical portion 123 and the cylindrical portion 14 of the piston bolt 11.
[0028] The core 150 has a cylindrical portion 151 that faces the movable core 130 in the axial direction ("up and down direction" in Figure 3) and has a recess 156 into which the axial end of the movable core 130 fits when the second valve portion 110 of the pilot valve 101 (see Figure 2) is seated on the second valve seat 109, and a flange portion 161 that extends radially outward from the outer diameter surface 155 on the axial end of the cylindrical portion 151. The cylindrical portion 151 has a small diameter cylindrical portion 152 that is fitted into the large diameter cylindrical portion 172 on the axial end of the housing 171 and inserted inside the axial end of the coil bobbin 126, and a large diameter cylindrical portion 154 on which the outer diameter surface 155 is formed. An annular member 178 is fitted to the large-diameter cylindrical portion 154 (outer diameter surface 155) to support the coil 125 (coil bobbin 126) by sandwiching it axially between it and the flange portion 149 of the core 148.
[0029] The core 150 is in contact with the radially outer peripheral edge of the annular surface 162 on the other axial end of the flange portion 161, where the end face on one axial end of the cylindrical portion 123 of the solenoid case abuts. As a result, a magnetic circuit is formed in the solenoid valve 120, consisting of the core 148, the cylindrical portion 123 of the solenoid case 121, the flange portion 161 of the core 150, the large-diameter cylindrical portion 154 of the core 150, the small-diameter cylindrical portion 152 of the core 150, and the movable iron core 130, around the outer circumference of the coil 125.
[0030] The housing 171 is formed in the shape of a bottomed cylinder with one end open in the axial direction. The housing 171 has a main cylindrical portion 173 positioned between the movable iron core 130 and the core 148, a small-diameter cylindrical portion 174 with a bottom connected to the other end in the axial direction of the main cylindrical portion 173 and into which a partition member 81 is fitted, a large-diameter cylindrical portion 172 connected to one end in the axial direction of the main cylindrical portion 173, and a flange portion 175 extending radially outward from the axial end of the large-diameter cylindrical portion 172. The flange portion 175 of the housing 171 is held by being sandwiched in the axial direction of the housing 171 by an annular surface 157 and an annular member 178 formed between the small-diameter cylindrical portion 152 and the large-diameter cylindrical portion 154 of the core 150.
[0031] The outer circumference of the other axial end of the annular member 178 is inserted into the cylindrical portion 123 of the solenoid case 121. The space between the solenoid case 121 and the annular member 178 is sealed by an O-ring 179. On the other hand, the space between the large-diameter cylindrical portion 172 of the housing 171 and the small-diameter cylindrical portion 152 of the core 150 is sealed by an O-ring 176.
[0032] The damping force adjustment mechanism is provided between the solenoid case 121 and the piston bolt 11 and includes a variable orifice 200 (see Figure 2) that operates to change the flow area of the working fluid flowing in the flow path connecting the first chamber 2A and the second chamber 2B depending on whether the working fluid is flowing from the first chamber 2A to the second chamber 2B or from the second chamber 2B to the first chamber 2A.
[0033] As shown in Figure 4, the core 150 has an outer peripheral projection 163 that protrudes from the radially outer end of the flange portion 161 toward one axial end, and an inner peripheral projection 165 formed on the inner circumference side of the outer peripheral projection 163. Between the outer peripheral projection 163 and the outer circumference of the spring disc 141, the first disc 201, spacer 211, check valve 221, and second disc 231 are stacked in order from one axial end to the other axial end. The spring disc 141, first disc 201, spacer 211, check valve 221, and second disc 231 are housed in a recess 191 formed on the end face on the other axial end side of the bottom 13 of the head 12 of the piston bolt 11 (see Figure 3).
[0034] The variable orifice 200 includes a first orifice 206 formed by cutting out a first disk 201, a second orifice 236 formed by cutting out a second disk 231, and a check valve 221 that is seated on the inner circumferential projection 165 so as to be able to seat and detach from it. The first orifice 206 communicates a first chamber 111 and an annular passage 135 formed on the outer circumference of the flange portion 161 of the core 150 (an annular passage 135 formed between the flange portion 161 and the head 12 of the piston bolt 11) via a passage 145 formed in the spring disk 141, the first orifice 206, and a passage 195.
[0035] The second orifice 236 is formed between the outer peripheral projection 163 and the inner peripheral projection 165 of the core 150, and connects the third chamber 115, defined by the core 150 and the check valve 221, to the annular passage 135. The annular passage 135 is connected to the first chamber 2A by a passage 139 (see Figure 3) formed in the head 12 (cylindrical portion 14) of the piston bolt 11.
[0036] Next, the main parts of this embodiment will be described. As shown in Figure 3 or Figure 5, the solenoid valve 120 has a solenoid chamber 93 formed inside the housing 171. The solenoid valve 120 has a partitioning member 81 fixed inside the housing 171 that divides the solenoid chamber 93 into a solenoid oil chamber 94 filled with hydraulic oil (working fluid) and a solenoid air chamber 95 (gas chamber) in which air can be retained. The partitioning member 81 is formed by sintering a polymer material such as rubber or plastic. The partitioning member 81 is formed of a porous material that functions to allow the passage of air (gas) and to block the passage of hydraulic oil.
[0037] The partition member 81 is formed in a plug shape with an opening at one end in the axial direction (the "lower side" in Figure 5). The partition member 81 has a large outer diameter portion 82 formed at one end in the axial direction and a small outer diameter portion 83 formed at the other end in the axial direction. The large outer diameter portion 82 and the small outer diameter portion 83 of the partition member 81 are formed coaxially. The partition member 81 has a projection 85 that protrudes from the center of the end face 84 at the other end in the axial direction toward the other end. As a result, the end face 84 of the partition member 81 is formed in an annular shape around the projection 85. The end face 86 of the projection 85 is formed perpendicular to the center line of the partition member 81 (the center line of the large outer diameter portion 82 and the small outer diameter portion 83). A chamfered portion 88 is formed on the edge between the end face 84 of the partition member 81 and the outer circumferential surface 87 of the small outer diameter portion 83.
[0038] The partition member 81 is fixed to the housing 171 by press-fitting its large outer diameter portion 82 into the small diameter cylindrical portion 174 of the housing 171. The partition member 81 is positioned axially (in the "up and down direction" in Figure 5) relative to the housing 171 by the end face 86 of the protruding portion 85 abutting (contacting) the bottom portion 177 of the housing 171. In other words, the partition member 81 is fixed to the housing 171 with the end face 86 of the protruding portion 85 abutting (in close contact) with the bottom portion 177 of the housing 171.
[0039] The solenoid valve 120 has an air chamber 85 (gas chamber) formed between the housing 171 and the partition member 81. The air chamber 85 has an air chamber side portion 96 formed on the outer circumference of the small outer diameter portion 83 and an air chamber upper portion 97 formed on the outer circumference of the protruding portion 85 of the partition member 81, in other words, between the end face 84 of the partition member 81 and the bottom portion 177 of the housing 171. The "upper portion" of the air chamber upper portion 97 refers to the upper part when the damping force adjustable shock absorber 1 is placed vertically. The air chamber side portion 96 and the air chamber upper portion 97 are in communication with each other.
[0040] The partition member 81 has a large inner diameter portion 89 that opens at one end in the axial direction, and a small inner diameter portion 90 that opens into the large inner diameter portion 89 at the other end in the axial direction. The large inner diameter portion 89 and the small inner diameter portion 90 of the partition member 81 are formed coaxially. A bush 132 that guides the operating rod 127 is mounted in the large inner diameter portion 89. The small inner diameter portion 90 accommodates the other end portion 128 of the operating rod 127 (the portion that protrudes upward from the bush 132 in Figure 5). Between the end portion 128 of the operating rod 127 and the small inner diameter portion 90 and bottom surface 91 of the partition member 81, a gap (part of the solenoid chamber 93) is formed that communicates with the rod passage 129 of the operating rod 127, in other words, is filled with hydraulic fluid.
[0041] Next, the flow of the working fluid in the damping force adjustable shock absorber 1 described above will be explained. During the compression stroke, the working fluid in the second chamber 2B is introduced into the compression side back pressure chamber 44 via the compression side passage 4, the groove (not shown) formed in the seat portion 55 on which the disc 53 (extension side check valve) is seated, the radial passage (not shown) formed in the spacer 54, the notch 25 formed in the shaft portion 15 of the piston bolt 11, and the notch 52 formed in the disc 51. Also during the compression stroke, the working fluid in the second chamber 2B is introduced into the extension side back pressure chamber 64 via the compression side passage 4, the groove (not shown) formed in the seat portion 55, the radial passage (not shown) formed in the spacer 54, the notch 25 formed in the shaft portion 15 of the piston bolt 11, the annular passage 24, the radial passage 29, the axial passage 21, the axial passage 22, the axial passage 23, the radial passage 27, the annular passage 26, and the notch 72 formed in the disc 71. This prevents the extension-side main valve 63 from opening due to the pressure in the second chamber 2B during the compression stroke.
[0042] Furthermore, during the compression stroke, the working fluid from the second chamber 2B is introduced into the rod back pressure chamber 138 via the compression-side passage 4, the groove formed in the seat portion 55 (reference numerals omitted), the radial passage formed in the spacer 54 (reference numerals omitted), the notch 25 formed in the shaft portion 15 of the piston bolt 11, the notch 33 formed in the cap 31, the notch 38 formed in the retainer 37, the second chamber 114, the notch formed in the check valve 35 (reference numerals omitted), passage 34, the first chamber 111, the spool back pressure chamber 136, the notch 137 formed in the operating rod 127, and the rod internal passage 129. In this way, in the low-speed region of the piston speed during the compression stroke, a portion of the pilot pressure applied to the compression-side back pressure chamber 44 can be applied to the rod back pressure chamber 138 as spool back pressure assist pressure.
[0043] Furthermore, in the low-speed region of the piston speed during the compression stroke, the spool back pressure assist pressure can be adjusted by directing a portion of the working fluid introduced from the second chamber 2B to the first chamber 111 to the first chamber 2A via a passage 145 formed in the spring disc 141, the first orifice 206 of the first disc 201 constituting the variable orifice 200, a passage 195 formed between the variable orifice 200 and the recess 191 of the piston bolt 11, an annular passage 135 formed on the outer circumference of the outer peripheral projection 163 of the core 150, and a passage 139 formed in the piston bolt 11. At this time, the damping force of the orifice characteristics provided by the first orifice 206 can be obtained.
[0044] On the other hand, during the extension stroke, the working fluid in the first chamber 2A passes through the extension-side passage 5, a groove portion (reference numeral omitted) formed in the seat portion 75 where the disk 73 (retraction-side check valve) seats, a radial passage (not shown) formed in the spacer 74, the annular passage 30, the radial passage 28, the axial passage 23, the radial passage 27, the annular passage 26, and the notch 72 formed in the disk 71 and is introduced into the extension-side back pressure chamber 64. Also, during the extension stroke, the working fluid in the first chamber 2A passes through the extension-side passage 5, a groove portion (reference numeral omitted) formed in the seat portion 75, a radial passage (not shown) formed in the spacer 74, the annular passage 30, the radial passage 28, the axial passage 23, the axial passage 22, the axial passage 21, the radial passage 29, the annular passage 24, and the notch 52 formed in the disk 51 and is introduced into the retraction-side back pressure chamber 44. Thereby, during the extension stroke, it is possible to prevent the retraction-side main valve 43 from opening due to the pressure in the first chamber 2A.
[0045] Further, during the extension stroke, the working fluid in the first chamber 2A passes through the passage 139 formed in the piston bolt 11, the annular passage 135 formed on the outer periphery of the outer peripheral protrusion 163 of the core 150, the passage 195 formed between the variable orifice 200 and the recess 191 of the piston bolt 11, the first orifice 206 of the variable orifice 200, the spool back pressure chamber 136, the notch 137 formed in the operating rod 127, and the rod inner passage 129 and is introduced into the rod back pressure chamber 138. Thus, in the low-speed region of the piston speed during the extension stroke, a spool back pressure assist pressure can be applied to the rod back pressure chamber 138. At this time, the damping force of the orifice characteristic by the first orifice 206 can be obtained.
[0046] Then, when the piston speed increases during the extension stroke and becomes faster than a predetermined speed, and the pressure in the third chamber 115, which communicates with the first chamber 2A via the second orifice 236 of the second disk 231, the annular passage 135, and the passage 139 that constitute the variable orifice 200, becomes higher than a predetermined pressure, the check valve 221 opens. As a result, in addition to the damping force of the orifice characteristic by the first orifice 206 before the check valve 221 opens, the working fluid in the first chamber 2A passes through the passage 139, the annular passage 135, the second orifice 236, and the third chamber 115, opens the check valve 221, and flows into the spool back pressure chamber 136, thereby obtaining the damping force of the orifice characteristic of the second orifice 236 and the valve characteristic by the check valve 221.
[0047] Thus, the variable orifice 200 operates such that the flow area is the flow area of the first orifice 206 until the piston speed during the extension stroke reaches a predetermined speed, and when the piston speed exceeds the predetermined speed, the flow area changes to the combined flow area of the first orifice 206 and the second orifice 236.
[0048] Note that the spool back pressure assist pressure during the extension stroke is adjusted by flowing a part of the working fluid introduced into the spool back pressure chamber 136 through the passage 145 formed in the spring disk 141, the first chamber 111, the passage 34 formed in the piston bolt 11, the check valve 35, the second chamber 114, the notch 38 formed in the retainer 37, the notch 33 formed in the cap 31, the notch 25 formed in the piston bolt 11, the radial passage (not shown) formed in the spacer 54, the notch (reference numeral omitted) formed in the seat portion 55, and the contraction side passage 4 to the second chamber 2B.
[0049] Here, in the conventional damping force adjusting type shock absorber, since there is no passage for removing air mixed in the working oil from the solenoid chamber during the assembly of the solenoid valve, the air bleeding property of the solenoid chamber is low. In the conventional damping force adjusting type shock absorber, due to the air remaining in the upper part of the solenoid chamber, the rising property of the damping force deteriorates (the time required for the resurge waveform of the damping force to stabilize becomes longer), so improving the air bleeding property of the solenoid chamber has been an issue.
[0050] In contrast, in this embodiment, the solenoid chamber 93 formed inside the housing 171 located inside the solenoid case 121 (case member) of the solenoid valve 120 is partitioned by a partitioning member 81, thereby forming a solenoid air chamber 95 (gas chamber) in the upper part of the solenoid chamber 93 (the upper region when the damping force adjustable shock absorber 1 is placed vertically) where air can accumulate. Furthermore, in this embodiment, the partitioning member 81 is made of a porous material that allows the passage of air (gas) and prevents the passage of hydraulic fluid. According to this embodiment, when hydraulic fluid is filled into the solenoid chamber 93, the air remaining in the solenoid oil chamber 94 passes from the solenoid oil chamber 94 through the partitioning member 81 (a passage with a small flow area that connects the solenoid oil chamber 94 and the solenoid air chamber 95, formed inside the partitioning member 81) and accumulates in the solenoid air chamber 95 when the pressure in the solenoid oil chamber 94 rises. In this embodiment, it is possible to improve the air venting performance of the solenoid chamber 93. In other words, it is possible to quickly move the air remaining in the solenoid oil chamber 94 from the solenoid oil chamber 94 through the partition member 81 to the solenoid air chamber 95, thereby resolving various problems caused by air remaining in the upper part of the solenoid chamber in conventional damping force adjustable shock absorbers. In this embodiment, the damping force rise time is improved (the time until the Lissajous waveform stabilizes is shortened), so in the vibration test of the damping force adjustable shock absorber 1 before factory shipment, the number of strokes required to obtain the predetermined damping force could be halved based on the applicant's experience. As a result, it is possible to significantly reduce the time required for the vibration test, excluding setup time, and improve the productivity of the damping force adjustable shock absorber 1. In this embodiment, the upper part of the air chamber 97 is formed on the outer circumference of the protrusion 85, which is formed on the upward end face 84 of the partition member 81, by bringing it into contact with the bottom 177 of the housing 171. In other words, the upper part of the air chamber 97 is formed above the upward end face 84 of the partition member 81. This makes it possible to smoothly move the air remaining in the upper part of the solenoid oil chamber 94 (upper part of the small inner diameter portion 90 of the partition member 81) from the end face 84 of the partition member 81 to the upper part of the air chamber 97, thereby improving the air release performance of the solenoid chamber 93 (solenoid oil chamber 94).In this embodiment, since the partition member 81 is formed of a porous material, it is possible to retain the air remaining in the solenoid oil chamber 94 inside the partition member 81. In other words, it is possible to add the volume of air that can be retained inside the partition member 81 to the air retention volume of the solenoid air chamber 95 (gas chamber), thereby securing a larger air retention volume.
[0051] The embodiments are not limited to those described above, and for example, they can be configured as follows. In the embodiments described above, the partition member 81 was formed from a polymer material such as rubber or plastic, but the partition member 81 may also be formed from a porous metal.
[0052] Furthermore, in the embodiment described above, a configuration was described in which the partition member 81 and the solenoid air chamber 95 (gas chamber) are applied to the solenoid valve 120 of a damping force adjustable shock absorber 1 with a built-in control valve in which the damping force adjustment mechanism is built into the cylinder 2. However, as shown in Figure 6, the partition member 81 and the solenoid air chamber 95 (gas chamber) are also applicable to the solenoid valve 320 of a damping force adjustable hydraulic shock absorber 301 with a control valve mounted laterally on the side of the outer tube 303.
[0053] Referring to Figure 6, an embodiment in which the partition member 81 and the solenoid air chamber 95 (gas chamber) are applied to the solenoid valve 320 of a control valve-mounted type damping force adjustable hydraulic shock absorber 301 will be described. Note that for parts corresponding to the previously described embodiment, the same designations and reference numerals will be used, and redundant explanations will be omitted.
[0054] The solenoid valve 320 is fixed inside the core 321 (housing) and has a partitioning member 81 that divides the solenoid chamber 93 into a solenoid oil chamber 94 filled with hydraulic fluid and a solenoid air chamber 95 (gas chamber) where air can be retained. The partitioning member 81 is fixed to the core 321 by press-fitting its large outer diameter portion 82 into the inner cylindrical portion 322 of the core 321. The partitioning member 81 is positioned axially (left-right direction in Figure 6) relative to the core 321 by a protruding portion 85 abutting against (contacting) the bottom portion 323 of the core 321.
[0055] Next, the flow of the working fluid in the solenoid valve 320 of the damping force adjustable shock absorber 301 will be explained. The working fluid that flows into the damping force adjustable shock absorber via the annular passage 324 and the flow path 325 is introduced into the annular chamber 331 via the introduction orifice 326, the introduction passage 327, the chamber 329 defined by the pilot case 328, and the passage 330 formed in the pilot case 328. When the pressure in chamber 331 reaches the opening pressure of the back pressure introduction valve 332, the back pressure introduction valve 332 opens, and the working fluid is introduced into the back pressure chamber.
[0056] Before the main valve 334 opens when the piston speed is in the low speed range, the hydraulic fluid is introduced into the valve chamber 338 defined by the pilot body 336 via the introduction orifice 326, introduction passage 327, chamber 329, and passage 337 formed in the pilot body 336, once a certain pressure is reached upstream of the pilot valve 335 and the pilot valve 335 opens. The hydraulic fluid introduced into the valve chamber 338 flows through the notch 340 formed in the cap 339, the annular passage 341 formed on the outer circumference of the cap 339, and the annular passage 342 formed on the outer circumference of the pilot case 328, and then flows to the reservoir 305 through the opening 304 formed in the outer tube 303.
[0057] Even when a partition member 81 and a solenoid air chamber 95 (gas chamber) are applied to the solenoid valve 320 of a control valve-mounted type damping force adjustable hydraulic shock absorber 301, the air remaining in the solenoid oil chamber 94 when the solenoid chamber 93 is filled with hydraulic fluid will pass from the solenoid oil chamber 94 through the partition member 81 and accumulate in the solenoid air chamber 95. As a result, even when a partition member 81 and a solenoid air chamber 95 (gas chamber) are applied to the solenoid valve 320 of a control valve-mounted type damping force adjustable hydraulic shock absorber 301, the air release performance of the solenoid chamber 93 can be improved.
[0058] Furthermore, the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. Also, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations.
[0059] This application claims priority under Japanese Patent Application No. 2025-017696, filed on 5 February 2025. The entire disclosure of Japanese Patent Application No. 2025-017696, filed on 5 February 2025, including the specification, claims, drawings, and abstract, is incorporated into this application by reference.
[0060] 1 Shock absorber, 2 Cylinder, 2A First chamber, 2B Second chamber, 3 Piston, 6 Piston rod, 11 Piston bolt, 120 Solenoid, 121 Solenoid case, 125 Coil, 150 Core, 200 Variable orifice
Claims
1. A damping force adjustable shock absorber comprising: a cylinder in which a working fluid is sealed; a rod with one axial end inserted into the cylinder and the other axial end protruding outward from the cylinder; a piston connected to the axial end of the rod and partitioning the inside of the cylinder; a passage through which the working fluid flows as the piston moves; and a solenoid valve equipped with a valve body that controls the flow rate of the working fluid flowing through the passage, wherein the solenoid valve comprises: a cylindrical case member; a coil housed in the case member; a movable iron core positioned radially inward of the coil; a shaft member fixed to the movable iron core and having the valve body fixed to its axial end; a housing between the movable iron core and the shaft member, covering the other axial end of the shaft member; a partitioning member fixed to the housing and partitioning the inside of the housing; and a gas chamber formed between the housing and the partitioning member, in which gas can be retained.
2. A damping force adjustable shock absorber according to claim 1, wherein the partition member is formed of a rubber or plastic polymer material through which gas can pass.
3. A damping force adjustable shock absorber according to claim 1, wherein the partition member is formed of a porous metallic material through which gas can pass.
4. A damping force adjustable shock absorber according to claim 1, wherein the partition member comprises a press-fit portion that is press-fitted into the housing and a protruding portion that protrudes in the axial direction and abuts against the housing.
5. A damping force adjustable shock absorber provided between the body of a vehicle and a wheel, comprising: a cylinder in which a working fluid is sealed; a rod with one axial end inserted into the cylinder and the other axial end protruding outward from the cylinder; a piston connected to the axial end of the rod and partitioning the inside of the cylinder; a passage through which the working fluid flows as the piston moves; a valve body that controls the flow rate of the working fluid flowing through the passage; a shaft member on which the valve body is provided at one axial end; a movable core fixed to the shaft member; and a solenoid valve equipped with a coil for driving the movable core; a case member housing the solenoid valve; a housing provided inside the case member and arranged to cover the shaft member or the movable core; and a partitioning member provided inside the housing and positioned closer to the vehicle body than the shaft member or the movable core, partitioning the inside of the housing and formed to allow gas to pass through.
6. A damping force adjustable shock absorber according to claim 5, wherein the partition member is formed of a rubber or plastic polymer material through which gas can pass.
7. A damping force adjustable shock absorber according to claim 5, wherein the partition member is formed of a porous metallic material through which gas can pass.
8. A damping force adjustable shock absorber according to claim 5, wherein the partition member comprises a press-fit portion that is press-fitted into the housing and a protruding portion that protrudes in the axial direction and abuts against the housing.