Shock absorber and method for manufacturing shock absorber

Abstract

Provided are a shock absorber that makes it possible to reduce manufacturing costs, and a method for manufacturing the shock absorber. A valve assembly is configured such that a housing (cap member) is formed by press-working a steel plate, and the housing is fixed to a fixed iron core by sandwiching a flange portion of the housing between a first fixed iron core and a second fixed iron core. This makes it possible to eliminate the brazing step in a conventional valve assembly process, thereby reducing the manufacturing costs of the shock absorber.

Description

Shock Absorber and Method for Manufacturing Shock Absorber

[0001] The present invention relates to a shock absorber that adjusts damping force by controlling the flow of working fluid with respect to the stroke of a piston rod, and to a method for manufacturing the shock absorber.

[0002] Patent Document 1 discloses a damping force adjustable shock absorber (hereinafter referred to as "conventional shock absorber") in which a damping force adjustment mechanism that controls the flow of working fluid in a common passage formed in a piston bolt by a pilot valve is built in a cylinder.

[0003] Japanese Unexamined Patent Application Publication No. 2022-152580

[0004] In the conventional shock absorber, in the assembly process of the solenoid valve, the cylindrical guide that guides the movable core, the fixed core, and the stainless steel cylinder that connects the guide and the fixed core are joined by brazing to form the valve assembly, and then the joint portion of the valve assembly is further finished. Therefore, many man-hours are required, which has been a factor of increasing manufacturing cost.

[0005] An object of the present invention is to provide a shock absorber capable of reducing manufacturing cost, and a method for manufacturing the shock absorber.

[0006] The buffer 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 cylindrical solenoid case in which a solenoid coil is housed; a cap member positioned radially inside the coil, with one axial end open and the other axial end having a bottom; a movable core inserted into the cap member and movable in the axial direction; and a fixed core positioned at one axial end of the movable core, wherein the fixed core has a first fixed core and a second fixed core, and the bottom of the cap member is separated from other members on the outside of the cap member, and a part of the axial end is fixed between the first fixed core and the second fixed core. The method for manufacturing the buffer of the present invention includes the steps of: inserting a movable iron core into a cap member; positioning a portion of one axial end of the cap member between a first fixed iron core and a second fixed iron core; assembling a valve assembly by joining the first fixed iron core and the second fixed iron core, thereby fixing a portion of one axial end of the cap member between the first fixed iron core and the second fixed iron core; and inserting the valve assembly radially inward into the coil.

[0007] According to one embodiment of the present invention, it is possible to provide a buffer that can reduce manufacturing costs, and a method for manufacturing the buffer.

[0008] This figure shows a cross-sectional view of a part of the buffer according to this embodiment. This figure shows an enlarged view of one axial end in Figure 1. This figure shows an enlarged view of the other axial end in Figure 1. This is an explanatory diagram of the manufacturing method of the buffer according to this embodiment, showing the state in which the movable iron core is inserted into the housing. This is an explanatory diagram of the manufacturing method of the buffer according to this embodiment, showing the state in which the first fixed iron core is press-fitted into the housing from the state shown in Figure 4. This is an explanatory diagram of the manufacturing method of the buffer according to this embodiment, showing the state in which the second fixed iron core is press-fitted onto the outer circumference of the first fixed iron core from the state shown in Figure 5. This is an explanatory diagram of the manufacturing method of the buffer according to this embodiment, showing the process of press-fitting the valve assembly into the coil.

[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 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 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 shock absorber 1 has 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 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 fixing portion 122 on the other end in the axial direction of the solenoid case 121 is fastened to the end portion 7 on the one end in the axial direction of the piston rod 6 by a plastic flow coupling.

[0012] The 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 includes 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] The extension valve mechanism 61 comprises 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 valve mechanism 41 and the extension valve mechanism 61.

[0018] 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 (see Figure 3) of the solenoid valve 120 is not energized, the pilot valve 101 restricts the flow of working fluid in the common passage 20 by the first valve portion 108 seating (fitting) onto the first valve seat 107.

[0022] 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 the one axial end of the valve body 105. When the coil 125 of the solenoid valve 120 is energized, the second valve portion 110 of the pilot valve 101 seats on the second valve seat 109, thereby restricting the flow of working fluid in the common passage 20.

[0023] A first chamber 111 is formed between the head 12 of the piston bolt 11 and the fixed iron core 150 of the solenoid valve 120, defined by a recess 114 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 115 is formed on the head 103 of the spool 102. The inner circumference of a spring disc 116, 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 115.

[0024] The head 103 of the spool 102 abuts against (is 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 116 when the coil 125 of the solenoid valve 120 is not energized. A spool back pressure chamber 136 is formed in the center of the axial end of the fixed iron core 150 (first core 151) 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.

[0025] When the control current to the coil 125 of the solenoid valve 120 is 0A (fail), the spool 102 moves in the opening direction of the pilot valve 101 due to the biasing force of the spring disc 116, causing the first valve portion 108 of the valve body 105 to seat (fit) on 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.

[0026] A bottomed cylindrical cap 31, with an opening at the other axial end, is fitted to 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 a sealing member 39 (O-ring). This forms an annular second chamber 112 between the cap 31 and the piston bolt 11. The cap 31 has a piston bolt insertion 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 piston bolt insertion 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 via a notch 25 formed in the shaft portion 15 of the piston bolt 11.

[0027] The second chamber 112 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 112 via a passage 34 formed in the bottom 13 of the piston bolt 11. 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 so as to be able to seat and detach from it. Multiple notches 38 (only "two" are shown in Figure 2) are formed on the inner circumference of the retainer 37 that restricts the opening of the check valve 35, connecting the second chamber 112 to the compression side back pressure chamber 44 via notches 33, 25, 24, and 52 formed in the disk 51.

[0028] As shown in Figure 3, the solenoid valve 120 includes a solenoid case 121, a coil 125, an operating rod 127, a movable core 130 fixed to the outer circumference of the operating rod 127, a fixed core 150, a bottomed cylindrical housing 91 (cap member) positioned inside the coil 125 in the radial direction (radial direction of the solenoid case 121), an insert core 141 positioned between the housing 91 and the coil 125, and a partition member 81 fixed inside the housing 91.

[0029] The operating rod 127 is slidably supported at both axial ends by bushings 132 press-fitted into the partition member 81 and bushings 133 press-fitted into the fixed core 150 (first fixed core 151). 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.

[0030] The fixed core 150 is composed of a first fixed core 151 and a second fixed core 161. The first fixed core 151 is positioned opposite the end face of the movable core 130 on one axial end side (the "lower side" in Figure 3). The first fixed core 151 has a first cylindrical portion 152, the other axial end portion of which is inserted into a large-diameter cylindrical portion 92 provided on one axial end side of the housing 91, and a flange portion 153 that protrudes radially outward from the axial end of the first cylindrical portion 152.

[0031] The second fixed core 161 is provided on the outer circumference of the axial end portion of the first fixed core 151 and is positioned to face the axial end face of the coil 125. The second fixed core 161 has a second cylindrical portion 162, the other axial end portion of which is inserted inside the axial end of the cylindrical portion 123 of the solenoid case 121. The inner circumferential surface 163 of the axial end of the second cylindrical portion 162 abuts against the outer circumferential surface 154 of the flange portion 153 of the first fixed core 151.

[0032] The second fixed core 161 has an annular first projection 164 that protrudes radially inward from the axial end of the second cylindrical portion 162. A tapered portion 166 is formed at the radially inward corner on the axial end side of the first projection 164, decreasing in diameter from the axial end side to the axial end side (upward in Figure 2). The second fixed core 161 has an annular second projection 165 that protrudes radially outward from the axial end of the second cylindrical portion 162. The axial end face 131 of the cylindrical portion 123 of the solenoid case 121 abuts against the axial end face 167 of the second projection 165 on the axial end side.

[0033] An annular seal groove 168 is formed on the outer circumferential surface of the second cylindrical portion 162 of the second fixed core 161, with a channel-shaped (C-shaped) cross-section formed by the axial plane (the plane containing the axis of the solenoid case 121). A seal member 158 (O-ring) is fitted into the seal groove 168 to seal the space between the second fixed core 161 and the cylindrical portion 123 of the solenoid case 121. The side surface of the seal groove 168 on one axial end is located on the same plane as the end surface 167 on the other axial end of the second projection 165.

[0034] The housing 91 is formed into a multi-stage (three-stage in this embodiment) bottomed cylindrical shape by press working (drawing) a steel plate. The housing 91 is arranged such that one end in the axial direction is open and the bottom portion 93 is located at the other end in the axial direction. The housing 91 has a main cylindrical portion 94 connected to one end in the axial direction of the bottom portion 93 and positioned between the movable iron core 130 and the insert core 141, a large-diameter cylindrical portion 92 connected to one end in the axial direction of the main cylindrical portion 94, and a flange portion 95 extending radially outward from the open end edge of one end in the axial direction of the large-diameter cylindrical portion 92.

[0035] A partitioning member 81 is fixed (press-fitted) to the bottom 93 of the housing 91, dividing the solenoid chamber defined inside the housing 91 into a solenoid oil chamber 82 filled with hydraulic oil (working fluid) and a solenoid air chamber 83 in which air can be retained. The partitioning member 81 is formed of, for example, a porous material that allows the passage of air (gas) and prevents the passage of hydraulic oil.

[0036] The housing 91 is fixed to the fixed core 150 by the flange portion 17 being sandwiched between the end face of the flange portion 153 of the first fixed core 151 on the other axial end and the end face of the first projection 165 of the second fixed core 161 on the one axial end. The outer side of the corner between the large diameter cylindrical portion 92 and the flange portion 95 of the housing 91 and the tapered portion 166 of the first projection 164 of the second fixed core 161 are sealed by a sealing member 159 (O-ring).

[0037] The insert core 141 has a cylindrical portion 142 and a flange portion 143 extending radially outward from the other axial end of the cylindrical portion 142. The flange portion 143 has an end face on one axial end that abuts against the other axial end of the coil 125, and its radially outward end face that abuts (fits) against the cylindrical portion 123 of the solenoid case 121. The cylindrical portion 142 extends axially from the radially inward end of the flange portion 143 toward the fixed core 150. As a result, a magnetic circuit is formed in the solenoid valve 120 around the coil 125, consisting of the insert core 141, the cylindrical portion 123 of the solenoid case 121, the fixed core 150, and the movable core 130.

[0038] Furthermore, a cover member 145 is provided on the other axial end of the insert core 141 to close the opening on the other axial end of the cylindrical portion 142 of the insert core 141. The cover member 145 is formed in a bottomed cylindrical shape with one axial end open. A flange portion 146 extending radially outward is formed on the open end edge of the cover member 145. The end face of the flange portion 146 on one axial end abuts against the end face on the other axial end (opposite side from the coil 125 side) of the flange portion 143 of the insert core 141. The housing 91 is arranged such that the bottom portion 93 does not abut against other members (in this embodiment, "cover member 145 and insert core 141") located outside the bottom portion 93 when the flange portion 95 is fixed to the fixed core 150, that is, when the flange portion 95 is sandwiched between the first fixed core 151 and the second fixed core 161.

[0039] Next, the flow of the working fluid in the buffer 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.

[0040] Furthermore, during the compression stroke, the working fluid from the second chamber 2B is introduced into the extension-side back pressure chamber 64 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 (not shown), 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.

[0041] 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 112, 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 working 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.

[0042] On the other hand, during the extension stroke, the working fluid from the first chamber 2A is introduced into the extension-side back pressure chamber 64 via the extension-side passage 5, the groove (not shown) formed in the seat portion 75 on which the disc 73 (retraction-side check valve) is seated, the 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 disc 71.

[0043] Furthermore, during the extension stroke, the working fluid in the first chamber 2A is introduced into the compression side back pressure chamber 44 via the extension side passage 5, the groove formed in the seat portion 75 (reference numerals omitted), the radial passage formed in the spacer 74 (not shown), 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. This prevents the compression side main valve 43 from opening due to the pressure in the first chamber 2A during the extension stroke.

[0044] Furthermore, the spool back pressure assist pressure during the extension stroke is adjusted by causing part of the working fluid introduced into the spool back pressure chamber 136 to flow to the second chamber 2B via the first chamber 111, the passage 34 formed in the piston bolt 11, the check valve 35, the second chamber 112, 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 formed in the spacer 54 (not shown), the notch formed in the seat portion 55 (reference numeral omitted), and the contraction-side passage 4.

[0045] Next, a method of manufacturing the shock absorber 1 according to the present embodiment will be described. Here, a part of the assembly procedure of the solenoid valve 120, more specifically, the procedure of assembling the valve assembly 171 (see FIG. 6) to the coil 125 will be described. First, as shown in FIG. 4, the movable iron core 130 is inserted into the housing 91 (cap member). Note that a partition member 81 is press-fitted into the bottom portion 93 inside the housing 91. Further, a bush 132 is press-fitted into the partition member 81. In addition, an operating rod 127 is fixed to the movable iron core 130 by caulking.

[0046] Next, the first cylindrical portion 152 of the first fixed iron core 151 is press-fitted into the large-diameter cylindrical portion 92 of the housing 91 with the movable iron core 130 inserted therein, and as shown in FIG. 5, the end face on the other axial end side (the "left side" in FIG. 5) of the flange portion 153 of the first fixed iron core 151 is brought into contact with the end face on one axial end side (the "right side" in FIG. 5) of the flange portion 95 of the housing 91. Note that a bush 133 is press-fitted into the first fixed iron core 151. Accordingly, both axial ends (the "left-right direction" in FIG. 5) of the operating rod 127 are slidably supported by the bushes 132 and 133. Further, after press-fitting the first fixed iron core 151 into the housing 91, a seal member 159 is attached to the housing 91.

[0047] Next, the housing 91 is inserted into the second cylindrical portion 162 of the second fixed core 161, and the flange portion 95 of the housing 91 is disposed between the flange portion 153 of the first fixed core 151 and the first projecting portion 164 of the second fixed core 161. Next, the flange portion 153 of the first fixed core 151 is press-fitted into the second cylindrical portion 162 of the second fixed core 161 to couple the first fixed core 151 and the second fixed core 161 together. Thereby, the valve assembly 171 is configured (assembled).

[0048] In the valve assembly 171 assembled in this manner, as shown in FIG. 6, the flange portion 95 of the housing 91 is sandwiched between the flange portion 153 of the first fixed core 151 and the first projecting portion 164 of the second fixed core 161, whereby the housing 91 is fixed to the fixed core 150. Further, the seal member 159 attached to the housing 91 is compressed between the outside of the corner between the large-diameter cylindrical portion 92 and the flange portion 95 of the housing 91, and the tapered portion 166 of the first projecting portion 164 of the second fixed core 161. Furthermore, after fixing the housing 91 to the fixed core 150, the seal member 158 is attached to the seal groove 168 of the second fixed core 161.

[0049] Next, as shown in FIG. 7, the valve assembly 171 is press-fitted into the coil 125. More specifically, the main body cylindrical portion 94 of the housing 91 is press-fitted into the cylindrical portion 142 of the insert core 141 of the coil assembly 173.

[0050] In a conventional shock absorber, in the assembly process of a solenoid valve, a cylindrical guide that guides a movable core, a fixed core, and a stainless steel cylinder that connects the guide and the fixed core are joined by brazing to configure a valve assembly, and then the joined portion of the valve assembly is finished. Therefore, many man-hours are required, which has been a factor that increases manufacturing costs. Further, in a conventional shock absorber, in the assembly process of a solenoid valve, a solenoid chamber is formed by closing the opening of the guide constituting the valve assembly with a closing member into which a bush for guiding an operating rod is press-fitted.

[0051] In contrast, in this embodiment, the closing member, guide, and cylinder in a conventional buffer are replaced with a single housing 91 (cap member) formed into a bottomed cylindrical shape by press working (drawing) a steel plate. Furthermore, the fixed core 150 is divided into a first fixed core 151 and a second fixed core 161, and the flange portion 95 formed at the open end edge of the housing 91 is sandwiched between the first fixed core 151 and the second fixed core 161, thereby configuring the solenoid valve 120 (valve assembly 171) to fix the housing 91 to the fixed core 150.

[0052] According to this embodiment, the brazing process in the assembly process of the solenoid valve of a conventional shock absorber can be eliminated. In addition, since the housing 91 is a single part formed by press working, it is possible to reduce parts costs and the assembly man-hours of the solenoid valve 120, thereby reducing the manufacturing cost of the solenoid valve 120 and, consequently, the manufacturing cost of the shock absorber 1. Furthermore, in this embodiment, the fixed iron core 150 is divided into two parts, the first fixed iron core 151 and the second fixed iron core 161, while the three parts of a conventional shock absorber—the closing member, guide, and cylinder—are replaced with a single molded part (housing 91). This reduces the number of parts in the valve assembly 171 and reduces the cost of managing parts. Furthermore, if the material of the housing 91 is not ferromagnetic (for example, a paramagnetic material such as austenitic stainless steel), a gap (magnetic gap) equal to the thickness of the housing 91 will be created, reducing the magnetic efficiency of the solenoid. However, in this embodiment, by placing the insert core 141 between the coil 125 and the movable iron core 130, it is possible to suppress the decrease in magnetic flux and ensure magnetic efficiency (magnetic flux). Also, in this embodiment, the bottom portion 93 of the housing 91 is positioned apart from other members (in this embodiment, the "lid member 145 and insert core 141") that are positioned outside the bottom portion 93, so that the strain of the solenoid case 121 can be absorbed by the gap between the bottom portion 93 of the housing 91 and the other members. As a result, in this embodiment, it is possible to apply plastic flow bonding to the coupling between the piston rod 6 and the solenoid case 121. In addition to plastic flow bonding, crimping, welding, etc., can be applied to the coupling between the piston rod 6 and the solenoid case 121. Furthermore, in this embodiment, the valve assembly 171, in which the movable core 130 and the fixed core 150 are integrated, is press-fitted into the coil 125. In other words, the housing 91 is press-fitted into the coil 125, thereby integrating the coil 125 and the valve assembly 171. This configuration makes it easier to assemble the valve assembly 171 into the coil 125 compared to the conventional method of press-fitting the valve assembly and coil into the coil.

[0053] 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.

[0054] This application claims priority under Japanese Patent Application No. 2025-040651, filed on 13 March 2025. The entire disclosure of Japanese Patent Application No. 2025-040651, filed on 13 March 2025, including the specification, claims, drawings, and abstract, is incorporated into this application by reference.

[0055] 1 Shock absorber, 2 Cylinder, 6 Piston rod (rod), 91 Housing (cap member), 96 Flange (part of one axial end), 121 Solenoid case, 125 Coil, 130 Movable core, 150 Fixed core, 151 First fixed core, 161 Second fixed core

Claims

1. A shock absorber comprising: a cylinder in which a working fluid is sealed; a rod having one axial end inserted into the cylinder and the other axial end protruding outward from the cylinder; a cylindrical solenoid case in which a solenoid coil is housed inside the solenoid case; a cap member positioned radially inside the coil, having an opening at one axial end and a bottom at the other axial end; a movable core inserted into the cap member and movable in the axial direction; and a fixed core positioned at one axial end of the movable core, wherein the fixed core comprises a first fixed core and a second fixed core, and the bottom of the cap member is separated from other members outside the cap member, and a portion of the axial end is fixed between the first fixed core and the second fixed core.

2. A shock absorber according to claim 1, wherein the first fixed core has a first cylindrical portion whose other axial end is inserted into the cap member, and a flange portion that protrudes radially outward from one axial end of the first cylindrical portion, the second fixed core has a second cylindrical portion arranged on the outer circumference of the flange portion and in contact with the flange portion, a first protruding portion that protrudes radially inward from the other axial end of the second cylindrical portion, and a second protruding portion that protrudes to the outside of the solenoid case from one axial end of the second cylindrical portion, and the cap member is sandwiched between the flange portion of the first fixed core and the first protruding portion of the second fixed core.

3. A shock absorber according to claim 1 or 2, wherein the solenoid case has a fixing portion fixed to the other axial end of the rod, and the coil and the cap member can be inserted into the solenoid case only from the end on the axial side opposite to the fixing portion.

4. A shock absorber according to claim 1, wherein the cap member is formed by press-forming a plate material.

5. A shock absorber according to claim 3, wherein the fixing portion is fixed to the rod by plastically deforming the rod or the solenoid case.

6. A shock absorber according to claim 3, wherein the fixing portion is fixed to the rod by welding.

7. A method for manufacturing a shock absorber, the shock absorber comprising: 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 cylindrical solenoid case in which a solenoid coil is housed inside the solenoid case; a cap member disposed radially inside the coil, with one axial end open and the other axial end having a bottom; a movable iron core inserted into the cap member and movable in the axial direction; and a fixed iron core disposed on one axial end side of the movable iron core and composed of a first fixed iron core and a second fixed iron core, the method for manufacturing the shock absorber comprising: inserting the movable iron core into the cap member; positioning a part of one axial end of the cap member between the first fixed iron core and the second fixed iron core; and assembling a valve assembly by joining the first fixed iron core and the second fixed iron core to fix a part of one axial end of the cap member between the first fixed iron core and the second fixed iron core, A method for manufacturing a buffer, comprising the step of inserting the valve assembly radially inward into the coil.

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