Damping force adjustment-type shock absorber

Abstract

Provided is a damping force adjustment-type shock absorber capable of expanding a damping force variable range. This damping force adjustment-type shock absorber is configured by providing, between a solenoid case and a piston rod member, a variable orifice in which a flow path area of a working fluid differs between when the working fluid flows from a second chamber side to a first chamber side during a compression stroke and when the working fluid flows from the first chamber side to the second chamber side during an extension stroke. Thus, the variable orifice is configured by making an aperture portion (second orifice) actuated only in the extension stroke and an aperture portion (first orifice) actuated in the compression stroke independent of each other. Therefore, it is possible to expand the damping force variable width of the damping force adjustment-type shock absorber.

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 incorporates a damping force adjustment mechanism that controls the flow of working fluid in a common passage 50 formed in a piston bolt 5 by a pilot valve.

[0003] Japanese Patent No. 6868111

[0004] In the conventional damping force adjustable shock absorber, since the orifice through which the working fluid supplied to the spool back pressure chamber passes during the compression stroke and the orifice through which the working fluid supplied to the spool back pressure chamber passes during the extension stroke are the same, it has been difficult to expand the damping force variable range.

[0005] An object of the present invention is to provide a damping force adjustable shock absorber capable of expanding the damping force variable range.

[0006] The damping force adjustable shock absorber of the present invention is provided between a solenoid case and a piston rod member, and includes a variable orifice that operates such that the flow area of the working fluid flowing in the flow path is different when flowing from the first chamber side to the second chamber side and when flowing from the second chamber side to the first chamber side. Further, the damping force adjustable shock absorber of the present invention is provided between a solenoid case and a piston rod member, and includes a variable orifice that varies the flow area of the working fluid flowing in the flow path when the moving speed of the piston is faster than a predetermined speed.

[0007] According to the damping force adjustable shock absorber according to an embodiment of the present invention, the damping force variable range of the damping force adjustable shock absorber can be expanded.

[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 in Figure 1. This figure shows an enlarged view of the other axial end in Figure 1. This figure shows an enlarged view of the main part in Figure 1. This is an explanatory diagram of this embodiment, a plan view of the spring disc. This is an explanatory diagram of this embodiment, a plan view of the first disc used in the variable orifice. This is an explanatory diagram of this embodiment, a plan view of the spacer used in the variable orifice. This is an explanatory diagram of this embodiment, a plan view of the check valve used in the variable orifice. This is an explanatory diagram of this embodiment, a plan view of the second disc used in the variable orifice.

[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 rod member 11 connected to the piston rod 6 via the solenoid case 121 of the solenoid 120. The piston rod member 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 shaft hole 9 of the piston 3. The solenoid case 121 is fastened to the end 7 on the 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 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 71 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 71 includes a bottomed cylindrical pilot case 72, an extension main valve 73 provided on the piston 3 side (the "upper side" in Figure 2) of the pilot case 72, and an extension back pressure chamber 74 formed between the pilot case 72 and the back surface of the extension main valve 73. The extension valve mechanism 71 has a seat portion 75 formed on the outer circumference of the end face on one axial end of the piston 3, with which the extension main valve 73 abuts so as to be able to seat and disseat. The pressure in the extension back pressure chamber 74 acts on the extension main valve 73 in the closing direction. The extension main valve 73 is a packing valve in which an annular packing 76 made of an elastic material contacts the inner circumferential surface of the pilot case 72 around its entire circumference.

[0016] The extension-side back pressure chamber 74 is connected to the second chamber 2B via a passage 77 formed in the pilot case 72 and a sub-valve 78. The sub-valve 78 opens when the pressure in the extension-side back pressure chamber 74 reaches a predetermined pressure, providing resistance to the flow of working fluid from the extension-side back pressure chamber 74 to the second chamber 2B. The extension-side back pressure chamber 74 is connected to the first pressure-receiving chamber 79 formed between the pilot case 72 and the sub-valve 78 via the passage 77 formed in the pilot case 72. The first pressure-receiving chamber 79 is defined by a first seat portion 80 formed on the outer circumference of the end face on one axial end of the pilot case 72, and the axial end of the passage 77 is open.

[0017] Furthermore, axial force is generated in the valve components constituting the compression valve mechanism 41 and the extension valve mechanism 71 by tightening a nut 16 screwed onto one axial end of the shaft portion 15 of the piston rod member 11, thereby compressing it between the head 12 of the piston rod member 11 and the washer 17.

[0018] As shown in Figure 2, the piston rod member 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 rod member 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 (no reference numerals) formed in the disk 54, an annular passage 24 formed between the pilot case 42 and the shaft portion 15 of the piston rod member 11, a notch 25 formed in the shaft portion 15 of the piston rod member 11, and a notch (no reference numerals) formed in the disk 56. On the other hand, the extension-side back pressure chamber 74 is connected to the extension-side passage 5 via a notch (no reference numerals) formed in the disk 84, an annular passage 26, a radial passage 27, an axial passage 23, a radial passage 28, an annular passage 30, and a notch (no reference numerals) formed in the disk 86.

[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 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) 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 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 rod member 11 and the core 150 of the solenoid 120, defined by a recess 193 (see Figure 4) formed on the end face of the bottom 13 of the head 12 of the piston rod member 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 120 is not energized, the head 103 of the spool 102 is pressed against (pressed against) the end face of the axial end of the operating rod 129 of the solenoid 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 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 129 and an internal rod passage 134 of the operating rod 129.

[0024] When the control current for the coil 125 of the solenoid 120 is 0A (fail), the biasing force of the spring disc 141 moves the spool 102 in the direction of opening the pilot valve 101, and the first valve portion 108 of the valve body 105 is seated (fitted) 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 to the outer circumference of the head 12 of the piston rod member 11. The space between the cap 31 and the head 12 of the piston rod member 11 is sealed by an O-ring 39. This forms an annular second chamber 114 between the cap 31 and the piston rod member 11. The cap 31 has an insertion hole 32 through which the shaft portion 15 of the piston rod member 11 is inserted. The cap 31 has a notch 33 formed in the 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 rod member 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 rod member 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 the notch 33, the passage 24, and the notch 55 formed in the check valve 54.

[0027] As shown in Figure 3, the solenoid 120 includes a solenoid case 121, a coil 125, a core 148, a core 150 (fixed core), an operating rod 129, and a plunger 130 (movable core) fixed to the outer circumference of the operating rod 129. The operating rod 129 is guided axially by a bush 132 mounted in a bottomed cylindrical holder 131 and a bush 133 mounted in the core 150. The solenoid case 121 is fastened to the piston rod member 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 rod member 11.

[0028] The core 150 has a cylindrical portion 151 that faces the plunger 130 in the axial direction ("up and down direction" in Figure 3) and has a recess 156 into which the axial end of the plunger 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 (large diameter portion) 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 yoke 171 (described later) and inserted inside the axial end of the coil bobbin 126, and a large diameter cylindrical portion 154 on which an 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 (omitted in reference numerals) of the cylindrical portion 123 of the solenoid case abuts against the end face (omitted in reference numerals) on one axial end of the flange portion 161. As a result, a magnetic circuit is formed on the outer circumference of the coil 125 in the solenoid 120, which includes the core 148, the cylindrical portion 123 of the solenoid case 121, the flange portion 161 (large diameter portion) of the core 150 (fixed core), the large diameter cylindrical portion 154 of the core 150, the small diameter cylindrical portion 152 of the core 150, and the plunger 130 (movable core).

[0030] The yoke 171 is formed as a bottomed cylindrical shape with one end open in the axial direction. The yoke 171 has a main cylindrical portion 173 positioned between the plunger 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 the holder 131 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 yoke 171 from the end of the large-diameter cylindrical portion 172 in the axial direction. The flange portion 175 of the yoke 171 is held by being sandwiched in the axial direction of the yoke 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 yoke 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 includes a variable orifice 200 provided between the solenoid case 121 and the piston rod member 11, which operates to change the flow area of ​​the working fluid flowing through 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, between the outer peripheral projection 163 (outer peripheral contact portion) of the core 150, which protrudes from the radially outer end of the flange portion 161 (large diameter portion) toward one axial end (piston 3 side), and the outer peripheral portion 142 of the spring disc 141 (see Figure 5), the first disc 201 (see Figure 6), spacer 211 (see Figure 7), check valve 221 (see Figure 8), and second disc 231 (see Figure 9) 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 portion 13 of the head portion 12 of the piston rod member 11 (see Figure 3), and whose cross-section is formed in a circular shape by a plane perpendicular to the center line of the piston rod member 11.

[0034] As shown in Figure 4 or Figure 5, the spring disc 141 has an outer peripheral portion 142 that abuts against the inner circumferential surface 192 (inner cylindrical surface) of the recess 191, an inner peripheral portion 143 that receives the spring receiver 112 of the spool 102 by its inner peripheral edge, a pair of connecting spring portions 144, 144 formed between the outer peripheral portion 142 and the inner peripheral portion 143, and a passage 145 formed between the outer peripheral portion 142 and the inner peripheral portion 143.

[0035] As shown in Figure 4 or Figure 6, the first disc 201 has an outer diameter portion 202 having an outer diameter smaller than the outer diameter of the spring disc 141, a plurality of (six in this embodiment) protruding portions 203 that project radially outward from the outer diameter portion 202, abut against the inner circumferential surface 192 of the recess 191, and are arranged at equal intervals in the circumferential direction along the outer diameter portion 202, an inner diameter portion 204 having an inner diameter substantially the same as the recess 193 formed in the piston rod member 11, and a first notch 205 that extends radially inward from the outer diameter portion 202.

[0036] As shown in Figure 4 or Figure 7, the spacer 211 has an outer diameter portion 212 having the same outer diameter as the outer diameter portion 202 of the first disk 201, a plurality of (six in this embodiment) protruding portions 213 that project radially outward from the outer diameter portion 212, abut against the inner circumferential surface 192 of the recess 191, and are arranged at equal intervals in the circumferential direction along the outer diameter portion 212, and an inner diameter portion 214 whose inner diameter is set such that when the spacer is superimposed on the first disk 201, it blocks a part of the first notch 205 of the first disk 201 (a part of the radially inner side of the first notch 205 is open).

[0037] As shown in Figure 4 or Figure 8, the check valve 221 has an outer diameter portion 222 having the same outer diameter as the first disk 201, a plurality of (six in this embodiment) protrusions 223 that project radially outward from the outer diameter portion 222, abut against the inner circumferential surface 192 of the recess 191, and are arranged at equal intervals in the circumferential direction along the outer diameter portion 222, and an inner diameter portion 224 whose inner diameter is set so that the inner circumferential portion (valve portion) seats on an inner circumferential protrusion 165 formed on the end face of one axial end of the core 150, on the inner circumferential side than the outer circumferential protrusion 163. The core 150 is formed such that the radial position (distance from the center line of the core 150) of the inner circumferential protrusion 165 (inner circumferential contact portion) coincides with the radial position of the outer diameter surface 153 of the small diameter cylindrical portion 152 (see Figure 3).

[0038] As shown in Figure 4 or Figure 9, the second disk 231 has an outer diameter portion 232 having the same outer diameter as the first disk 201, a plurality of (six in this embodiment) protruding portions 233 that project radially outward from the outer diameter portion 232, abut against the inner circumferential surface 192 of the recess 191, and are arranged at equal intervals in the circumferential direction along the outer diameter portion 232, an inner diameter portion 234 having substantially the same inner diameter as the first disk 201, and a second notch 235 extending radially inward from the outer diameter portion 232. The second notch 235 is formed to connect the annular passage 135 on the outer circumference side (right side in Figure 4) of the outer peripheral protruding portion 163 of the core 150 with the third chamber 115 on the inner circumference side (left side in Figure 4).

[0039] As shown in Figure 4, the variable orifice 200 includes a first orifice 206 (restricted portion) formed by a first notch 205 of the first disk 201, a second orifice 236 (restricted portion) formed by a second notch 235 of the second disk 231, and a check valve 221 that is seated detachably on the inner circumferential projection 165. The first orifice 206 communicates an annular passage 135 formed on the outer circumference of the flange portion 161 of the core 150 (annular passage 135 formed between the flange portion 161 and the head 12 of the piston rod member 11) and the first chamber 111 via a passage 195 formed along the inner circumferential surface 192 of the recess 191 and a passage 145 formed in the spring disk 141.

[0040] 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 portion 12 (cylindrical portion 13) of the piston rod member 11.

[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 from the second chamber 2B is introduced into the compression side back pressure chamber 44 via the compression side passage 4, the notch (no reference numerals) formed in the extension side check valve 56, the notch 25 formed in the shaft portion 15 of the piston rod member 11, and the notch (no reference numerals) formed in the disc valve 54. Also during the compression stroke, the working fluid from the second chamber 2B is introduced into the extension side back pressure chamber 74 via the compression side passage 4, the notch (no reference numerals) formed in the disc 56, the notch 25 formed in the shaft portion 15 of the piston rod member 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 (no reference numerals) formed in the disc 84. This prevents the extension-side main valve 73 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, a notch (no reference numerals) formed in the disc 56, a notch 25 formed in the shaft portion 15 of the piston rod member 11, a notch 33 formed in the cap 31, a notch 38 formed in the retainer 37, the second chamber 114, a notch (no reference numerals) formed in the check valve 35, a chamber (no reference numerals) formed on the inner circumference side of the seat portion 36, passage 34, the first chamber 111, the spool back pressure chamber 136, a notch 137 formed in the working rod 129, and the rod internal passage 134. 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] Then, in the low-speed region of the piston speed during the compression stroke, a part of the working fluid introduced from the second chamber 2B to the first chamber 111 is passed through the passage 145 formed in the spring disk 141, the first orifice 206 (constriction part) of the first disk 201 constituting the variable orifice 200, the passage 195 formed between the variable orifice 200 and the inner peripheral surface 192 of the concave part 191 of the piston rod member 11, the annular passage 135 formed on the outer periphery of the outer peripheral protrusion 163 (outer peripheral contact part) of the core 150 (fixed iron core), and the passage 139 formed in the piston rod member 11, and flows into the first chamber 2A, whereby the spool backpressure assist pressure can be adjusted. At this time, the damping force of the orifice characteristic 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 is introduced into the extension-side backpressure chamber 74 via the extension-side passage 5, the notch (reference numeral omitted) formed in the disk 86, the annular passage 30, the radial passage 28, the axial passage 23, the radial passage 27, the annular passage 26, and the notch (reference numeral omitted) formed in the disk 84. Also, during the extension stroke, the working fluid in the first chamber 2A is introduced into the compression-side backpressure chamber 44 via the extension-side passage 5, the notch (reference numeral omitted) formed in the disk 86, 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 (reference numeral omitted) formed in the disk 54. Thereby, during the extension stroke, it is possible to prevent the compression-side main valve 43 from opening due to the pressure in the first chamber 2A.

[0045] Furthermore, during the extension stroke, the working fluid in the first chamber 2A is introduced into the rod back pressure chamber 138 via the passage 139 formed in the piston rod member 11, the annular passage 135 formed on the outer circumference of the outer peripheral projection 163 (outer peripheral contact portion) of the core 150 (fixed iron core), the passage 195 formed between the variable orifice 200 and the inner circumferential surface 192 of the recess 191 of the piston rod member 11, the first orifice 206 (restriction portion) of the first disk 201 constituting the variable orifice 200, the spool back pressure chamber 136, the notch 137 formed in the working rod 129, and the rod internal passage 134. In this way, spool back pressure assist pressure can be applied to the rod back pressure chamber 138 in the low-speed region of the piston speed during the extension stroke. At this time, the damping force of the orifice characteristics by the first orifice 206 can be obtained.

[0046] Then, during the extension stroke, the piston speed increases and exceeds a predetermined speed, and when the pressure in the third chamber 115, which is in communication with the first chamber 2A via the second orifice 236 (throttling portion) of the second disk 231 constituting the variable orifice 200, the annular passage 135, and passage 139, becomes higher than a predetermined pressure, the check valve 221 opens. As a result, in addition to the damping force of the orifice characteristics by the first orifice 206 before the check valve 221 opens, the damping force of the orifice characteristics of the second orifice 236 and the valve characteristics of the check valve 221 can be obtained as the working fluid in the first chamber 2A flows through passage 139, annular passage 135, second orifice 236, and third chamber 115, opening the check valve 221 and flowing into the spool back pressure chamber 136.

[0047] Thus, the variable orifice 200 operates such that, up to a predetermined piston speed during the extension stroke, its flow path area is the flow path area of ​​the first orifice 206, and when the piston speed exceeds the predetermined speed, it changes to a flow path area that is the sum of the first orifice 206 and the second orifice 236.

[0048] Note that the spool backpressure assist pressure during the extension stroke can be adjusted by flowing a part of the working fluid introduced into the spool backpressure chamber 136 through the passage 145 formed in the spring disk 141, the first chamber 111, the passage 34 formed in the piston rod member 11, the check valve 35, the second chamber 114, the notch 38 formed in the retainer 37, the notch 25 formed in the piston rod member 11, and the notch (reference numeral omitted) formed in the disk 56, and the compression-side passage 4 to the second chamber 2B.

[0049] In a conventional damping force adjustable shock absorber, since the orifice through which the working fluid supplied to the spool backpressure chamber passes to apply the spool backpressure assist pressure during the compression stroke is the same as the orifice through which the working fluid supplied to the spool backpressure chamber passes to apply the spool backpressure assist pressure during the extension stroke, it has been difficult to expand the variable range of the damping force.

[0050] In contrast, in this embodiment, a damping force adjustable shock absorber 1 is configured by providing a variable orifice 200 between the solenoid case 121 and the piston rod member 11, such that the flow area of ​​the working fluid differs when the working fluid flows from the second chamber 2B to the first chamber 2A during the compression stroke and when the working fluid flows from the first chamber 2A to the second chamber 2B during the extension stroke. In this embodiment, during the compression stroke, the working fluid introduced from the second chamber 2B to the first chamber 111 via the flow path passes through the first orifice 206 (restriction portion) of the variable orifice 200 and flows to the first chamber 2A. On the other hand, during the extension stroke, the working fluid introduced from the first chamber 2A to the annular passage 135 via the passage 139 flows through the first orifice 206 of the variable orifice 200 to the second chamber 2B until the piston speed reaches a predetermined speed. When the piston speed exceeds the predetermined speed and the pressure in the third chamber 115 exceeds a predetermined pressure, the check valve 221 opens, and a portion of the working fluid introduced from the first chamber 2A flows through the second orifice 236 (throttling portion) of the variable orifice 200 to the second chamber 2B. Thus, in this embodiment, the flow path area of ​​the variable orifice 200 during the extension stroke is the flow path area of ​​the first orifice 206 until the piston speed reaches a predetermined speed, thereby obtaining the damping force of the orifice characteristics provided by the first orifice 206. Furthermore, during the extension stroke, the flow area of ​​the variable orifice 200 becomes the sum of the flow area of ​​the first orifice 206 and the flow area of ​​the second orifice 236 when the piston speed exceeds a predetermined speed, thereby obtaining orifice characteristics due to a composite orifice with the first orifice 206 and the second orifice 236 arranged in parallel. Moreover, since the check valve 221 opens when the piston speed exceeds a predetermined speed during the extension stroke, in addition to the orifice characteristics due to the composite orifice described above, damping force due to the valve characteristics of the check valve 221 can be obtained. According to this embodiment, the variable orifice 200 is configured with a throttling section (second orifice 236) that operates only during the extension stroke and a throttling section (first orifice 206) that operates during the compression stroke independently, so the variable damping force range of the damping force adjustable shock absorber 1 can be expanded.

[0051] Furthermore, in this embodiment, an annular inner circumferential projection 165 (inner circumferential contact portion) is formed on the end face of the core 150 (fixed iron core) on one axial end, and the radial position of the inner circumferential projection 165 is set to overlap with the outer diameter surface 153 of the small diameter cylindrical portion 152 of the core 150. A magnetic circuit is formed on the outer circumference of the coil 125 of the solenoid 120, comprising the core 148, the cylindrical portion 123 of the solenoid case 121, the flange portion 161 (large diameter portion) of the core 150 (fixed iron core), the large diameter cylindrical portion 154 of the core 150, the small diameter cylindrical portion 152 of the core 150, and the plunger 130 (movable iron core). According to this embodiment, by forming the inner circumferential projection 165 on the end face of the core 150 on one axial end, it is possible to improve the magnetic efficiency of the core 150 and prevent magnetic saturation from occurring. This makes it possible to make the core 150 thinner in the axial direction, and consequently, to miniaturize the damping force adjustable shock absorber 1.

[0052] 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.

[0053] This application claims priority under Japanese Patent Application No. 2024-232399, filed on 27 December 2024. The entire disclosure of Japanese Patent Application No. 2024-232399, filed on 27 December 2024, including the specification, claims, drawings, and abstract, is incorporated into this application by reference.

[0054] 1 Shock absorber, 2 Cylinder, 2A First chamber, 2B Second chamber, 3 Piston, 6 Piston rod, 11 Piston rod member, 120 Solenoid, 121 Solenoid case, 125 Coil, 150 Core, 200 Variable orifice

Claims

1. A damping force adjustable shock absorber, the damping force adjustable shock absorber comprises: 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 out of the cylinder; a solenoid case connected to the axial end of the rod, the solenoid case housing a solenoid coil inside and covering a part of the core of the solenoid; a piston rod member with a cylindrical section fastened to the axial end of the solenoid case; a piston provided on the piston rod member that divides the inside of the cylinder into two chambers, a first chamber and a second chamber; and a flow path provided on the solenoid case or the piston rod member that connects the first chamber and the second chamber and through which the working fluid flows. A damping force adjustable shock absorber comprising: a variable orifice provided between the solenoid case and the piston rod member, which operates such that the flow area of ​​the working fluid flowing in the flow path differs when the fluid flows from the first chamber to the second chamber and when it flows from the second chamber to the first chamber.

2. A damping force adjustable shock absorber according to claim 1, wherein the variable orifice comprises a throttling portion that constantly connects the first chamber and the second chamber of the solenoid case and the piston rod member, and a check valve that allows unidirectional flow between the first chamber and the second chamber and suppresses non-unidirectional flow between the first chamber and the second chamber.

3. A damping force adjustable shock absorber according to claim 1, wherein the solenoid comprises a movable core disposed on the inner circumference side of the solenoid case and movable in the axial direction, and a fixed core disposed axially opposite to the movable core and attracting the movable core, the fixed core comprising an outer circumference contact portion that contacts the outer circumference side of the variable orifice and an inner circumference contact portion that contacts the inner circumference side of the variable orifice.

4. A damping force adjustable shock absorber according to claim 3, wherein the variable orifice is provided between the solenoid case and the piston rod member and has a throttling portion that constantly connects the first chamber and the second chamber of the solenoid case and the piston rod member, and has a check valve that allows unidirectional flow between the first chamber and the second chamber and suppresses unidirectional flow between the first chamber and the second chamber, and the check valve is in contact with the inner circumferential contact portion and closes up to a predetermined pressure when the pressure received from the working fluid by the movement of the piston is higher than the predetermined pressure, the damping force adjustable shock absorber.

5. A damping force adjustable shock absorber according to claim 3, wherein the fixed iron core has a cylindrical portion and a large-diameter portion extending radially outward from the outer diameter surface of the cylindrical portion, and the inner circumferential contact portion is arranged such that its radial position on the fixed iron core overlaps with at least the outer diameter surface of the cylindrical portion.

6. A damping force adjustable 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 solenoid case connected to the axial end of the rod, the solenoid case housing a solenoid coil inside the solenoid case and covering a part of the core of the solenoid; a piston rod member whose cylindrical portion is fastened to the axial end of the solenoid case; a piston provided on the piston rod member that divides the inside of the cylinder into two chambers, a first chamber and a second chamber; a flow path provided on the solenoid case and the piston rod member that connects the first chamber and the second chamber and through which the working fluid flows; and a variable orifice provided between the solenoid case and the piston rod member that changes the flow area of ​​the working fluid flowing through the flow path when the moving speed of the piston is faster than a predetermined speed.

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