Shock absorbing device and suspension device

Abstract

This shock absorbing device comprises: an annular elastic member 110 having elasticity; a seal member 120 that is arranged on the opposite side to a first piston part with respect to the elastic member 110 in the axial direction of a rod and is capable of coming into contact with the inner peripheral surface of a collar 17; and a regulation member 150 that regulates the axial movement of the elastic member 110 and the seal member 120, wherein the seal member 120 has a cylindrical base part 130 and a protrusion 140 that protrudes annularly to the elastic member 110 side from the outer periphery of an opposite surface 131 of the base part 130 facing the elastic member 110 and that is capable of coming into contact with the outer periphery of the elastic member 110, a recess 132 recessed on the inner side of the protrusion 140 from the opposite surface 131 to the side opposite the elastic member 110 is formed in the base part 130, and a groove 141 communicating the inside and the outside in at least a part in the circumferential direction is formed in the protrusion 140.

Description

shock absorbers, suspension devices

[0001] The present invention relates to shock absorbers and suspension systems.

[0002] For example, the vibration damper described in Patent Document 1 is configured as follows: a first piston is fixed to a piston rod that is movable axially within a cylinder. A second piston is attached to the piston rod. The second piston enters a pressure cylinder having a pressure chamber according to its stroke. The second piston has a throttle opening through which a damping medium moves. A pin penetrating axially is provided in the center of the bottom of the pressure cylinder, and a pressure limiting valve that opens in the direction of flow from the pressure cylinder to the base valve body is provided. The pressure limiting valve has a spherical valve and a spring that applies a force to the valve in a direction that closes the flow path.

[0003] DE102019206510A

[0004] The pressure limiting valve described in Patent Document 1 opens when a set internal pressure is reached during the compression stroke, during which the piston rod moves into the cylinder, allowing the damping medium to flow out of the pressure cylinder to prevent the pressure inside the cylinder from becoming too high. Because this pressure limiting valve is located at the bottom of the pressure cylinder, it is difficult to apply it to the extension stroke, during which the piston rod moves out of the cylinder. To apply it to the extension stroke, the cylinder would need to be turned upside down, which would require a separate hole at the bottom through which the piston rod passes. This hole would need to be airtight with respect to the piston rod so that the pressure control valve could function. Furthermore, the press-fit control valve would need to be offset to prevent the pressure limiting valve from interfering with the piston rod. The present invention aims to provide a shock absorber and the like that allows for a high degree of freedom in designing layouts and allows for a high degree of freedom in designing damping force characteristics by preventing the pressure inside the cylinder from becoming too high during the extension stroke.

[0005] The present invention, which was completed with the above object in mind, comprises a rod partially inserted into a cylindrical cylinder, a first piston portion fixed to the rod and defining a space within the cylinder, a cylindrical collar disposed within the cylinder on the rod side of the first piston portion, and a second piston portion fixed to the rod coaxially with the first piston portion and capable of entering the collar to form a high-pressure chamber in the space within the collar, the high-pressure chamber having a higher pressure than the first piston portion side, wherein the second piston portion comprises an annular elastic member and a second piston portion configured to be elastically supported by a ring-shaped ... in the axial direction of the rod. and a restricting member that restricts the axial movement of the elastic member and the sealing member, wherein the sealing member has a cylindrical base and a convex portion that protrudes annularly from the outer periphery of an opposing surface of the base that faces the elastic member toward the elastic member and is capable of contacting the outer periphery of the elastic member, the base having a recess formed inside the convex portion that is recessed from the opposing surface on the opposite side to the elastic member, and the convex portion has a groove formed in at least a portion of its circumferential direction that connects the inside and outside.

[0006] According to the present invention, it is possible to provide a shock absorber or the like that allows for highly flexible setting of the layout while preventing the pressure inside the cylinder from becoming too high during the extension stroke, thereby allowing for highly flexible setting of the damping force characteristics.

[0007] FIG. 4 is a diagram showing an example of a schematic configuration of a suspension device. FIG. 4 is an example of an enlarged view of part II of FIG. 1. FIG. 4 is an example of a view of a seal member as seen from a first side in the axial direction. FIG. 4 is an example of a cross-sectional view of the second piston portion in an extension stroke in which the amount of protrusion of the rod from the cylinder portion increases. FIG. 4 is an example of an enlarged view of part V of FIG. 4. FIG. 4 is an example of a cross-sectional view of the second piston portion in an extension stroke. FIG. 4 is an example of a cross-sectional view of the second piston portion in a compression stroke in which the amount of protrusion of the rod decreases. FIG. 4 is a diagram showing an example of a schematic configuration of the second piston portion according to a second embodiment. FIG. 4 is a diagram showing an example of a state of the second piston portion in a compression stroke in which the amount of protrusion of the rod decreases. FIG. 4 is a diagram showing an example of a schematic configuration of the second piston portion according to a third embodiment. FIG. 4 is an example of a view of an elastic member according to a third embodiment as seen in the axial direction. FIG. 4 is a diagram showing an example of a schematic configuration of a shock absorber according to a fourth embodiment. FIG. 4 is an example of a cross-sectional view of the third piston portion in a compression stroke.

[0008] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. <First Embodiment> Fig. 1 is a diagram showing an example of the schematic configuration of a suspension system 1. The suspension system 1 is a strut-type suspension used in four-wheeled vehicles such as passenger automobiles, and as shown in Fig. 1, includes a shock absorber 2 and a coil spring 3 arranged on the outside of the shock absorber 2. The suspension system 1 also includes a lower spring seat 4 that supports an end of the coil spring 3 on a first axial side (lower side in Fig. 1) of a rod 20 (described later), and an upper spring seat 5 that supports an end of the coil spring 3 on a second axial side (upper side in Fig. 1) of the rod 20.

[0009] The suspension 1 also includes a vehicle-body-side mounting bracket 6 that is attached to the second axial end of the rod 20 for mounting the suspension 1 to a vehicle, and a wheel-side mounting bracket 7 that is fixed to a first axial end of the rod 20 in the cylinder portion 10 (described later) for mounting the suspension 1 to a wheel. The suspension 1 also includes a dust cover 8 that covers at least a portion of the cylinder portion 10 and the rod 20.

[0010] Hereinafter, the axial direction of the rod 20 may be simply referred to as the "axial direction." The axial direction is also the direction of the center line of a cylindrical cylinder 11, which will be described later. The first axial side (the lower side in FIG. 1 ) and the second axial side (the upper side in FIG. 1 ) may be simply referred to as the "first side" and the "second side," respectively. Furthermore, a direction intersecting the axial direction (for example, a perpendicular direction) may be referred to as the "radial direction." In the radial direction, the side of the center line of the cylinder 11 may be simply referred to as the "inner side," and the side away from the center line may be simply referred to as the "outer side."

[0011] The shock absorber 2 will be described in detail below. The shock absorber 2 includes a cylinder portion 10 that stores oil, and a rod 20 that has a second end that protrudes from the cylinder portion 10 and a first end that is slidably inserted into the cylinder portion 10. The shock absorber 2 also includes a first piston portion 30 that is provided at the first end of the rod 20, and a bottom valve 40 that is provided at the first end of the cylinder portion 10. The shock absorber 2 also includes a second piston portion 100 that is provided on the second side of the first piston portion 30.

[0012] [Cylinder section 10] The cylinder section 10 includes a cylinder 11 that accommodates oil, an outer cylindrical body 12 that is provided on the outside of the cylinder 11, and a bottom cover 13 that closes a first end of the outer cylindrical body 12. The cylinder 11 and the outer cylindrical body 12 are arranged so that the center line direction of the cylinder coincides with the axial direction. The cylinder section 10 forms a reservoir chamber R with the outer peripheral surface of the cylinder 11 and the inner peripheral surface of the outer cylindrical body 12. The interior of the outer cylindrical body 12 is filled with oil, which is an example of a fluid.

[0013] The cylinder portion 10 also includes a rod guide portion 14 that movably supports the rod 20, a bump stopper cap 15 attached to the second end of the outer cylinder body 12, and an oil seal 16 that prevents oil leakage from the cylinder portion 10 and the intrusion of foreign matter into the cylinder portion 10. The cylinder portion 10 also includes a cylindrical collar 17 that is provided at the second end of the cylinder 11 and has a chamfer formed at the first end, the inner diameter of which increases toward the first end. By making the collar 17 cylindrical and not providing a pressure control valve as described in Patent Document 1, holes for passing the rod 20 and airtight treatment are not required, improving layout flexibility. The collar 17 may be joined to the cylinder 11 by, for example, welding or adhesive.

[0014] [Rod 20] The rod 20 is a solid or hollow rod-shaped member, and has a columnar or cylindrical rod portion 21. The rod 20 also has a lower mounting portion 22 for mounting the first piston portion 30 at its lower end, and an upper mounting portion 23 for mounting the vehicle body mounting bracket 6 at its upper end. Male threads are formed at the ends of the lower mounting portion 22 and the upper mounting portion 23.

[0015] A first groove 211 (see FIG. 2) and a second groove 212 (see FIG. 2) are formed at predetermined positions on the rod portion 21, recessed from the outer peripheral surface over the entire circumference. For example, the cross-sectional shape of the first groove 211 cut along a plane parallel to the axial direction is triangular, and the cross-sectional shape of the second groove 212 cut along a plane parallel to the axial direction is semicircular.

[0016] [First Piston Section 30] The first piston section 30 includes a first piston 31, a valve group 32 that closes first ends of some of the oil passages formed in the first piston 31, and a valve group 33 that closes second ends of some of the oil passages formed in the first piston 31. The first piston 31 contacts the inner peripheral surface of the cylinder 11 via a member that is provided on its outer peripheral surface and seals a gap between the outer peripheral surface of the first piston 31 and the inner peripheral surface of the cylinder 11, and divides the space in the cylinder 11 in which oil is sealed into a first chamber Y1 on the first side of the first piston 31 and a second chamber Y2 on the second side of the first piston 31.

[0017] [Bottom Valve 40] The bottom valve 40 includes a valve body 41 having a plurality of oil passages passing through in the axial direction, a valve 42 provided on a first side of the valve body 41, and a valve 43 provided on a second side of the valve body 41. The valve body 41 of the bottom valve 40 separates a first chamber Y1 from a reservoir chamber R.

[0018] [Second piston portion 100] Figure 2 is an example of an enlarged view of portion II in Figure 1. Figure 3 is an example of a view of the seal member 120 as viewed from the first axial side. The second piston portion 100 includes an annular elastic member 110 and a seal member 120 that is arranged on the opposite side of the first piston portion 30 (i.e., the second side) of the elastic member 110 in the axial direction of the rod 20 and that is capable of contacting the inner circumferential surface of the collar 17. The second piston portion 100 also includes a restricting member 150 that restricts axial movement of the elastic member 110 and the seal member 120, and a clip 180 that has a circular cross section and a C-shaped shape when viewed in the axial direction and that restricts axial movement of the restricting member 150.

[0019] The elastic member 110 is a ring-shaped plate made of, for example, metal. The inner diameter of the elastic member 110 is equal to or greater than the diameter of the outer circumferential surface of the rod portion 21 of the rod 20, and the outer diameter of the elastic member 110 is smaller than the diameter of the inner circumferential surface of the collar 17.

[0020] (Sealing member 120) The sealing member 120 is a cylindrical member made of, for example, metal or resin. More specifically, the sealing member 120 has a cylindrical base 130 and a protruding portion 140 that protrudes in an annular shape from the outer periphery of an opposing surface 131 of the base 130 that faces the elastic member 110 toward the elastic member 110 (in other words, the first side).

[0021] The inner diameter of the base 130 is larger than the diameter of the outer peripheral surface of the rod portion 21 of the rod 20, and the outer diameter of the base 130 is equal to the diameter of the inner peripheral surface of the collar 17. The base 130 has a plurality of recesses 132 (ten in the example shown in FIG. 3 ) formed in the circumferential direction at a position inside the protrusions 140, the recesses 132 being recessed from the opposing surface 131 toward the opposite side to the elastic member 110 (in other words, the second side).

[0022] The cross section of the protrusion 140 taken along a plane parallel to the axial direction is a rectangle with the radial direction as the longitudinal direction and the axial direction as the lateral direction. However, the inner peripheral surface of the protrusion 140 may be an inclined surface whose inner diameter increases toward the first side. This is because oil can flow more smoothly along the inclined surface.

[0023] Grooves 141 extending in the radial direction are formed in the protrusions 140 so as to connect the inner and outer regions of the protrusions 140. The grooves 141 are formed at positions that do not overlap with the recesses 132 in the circumferential direction. In the example shown in FIG. 3 , one groove 141 is formed, but the number of grooves 141 is not limited to one and may be multiple. However, when cut along a plane perpendicular to the axial direction, the total cross-sectional area of ​​the one or multiple grooves 141 is smaller than the total cross-sectional area of ​​the multiple recesses 132.

[0024] (Restriction Member 150) The restriction member 150 has a first member 160 and a second member 170 arranged side by side in the axial direction. The restriction member 150 can be, for example, a member made of metal or resin.

[0025] The first member 160 has a cylindrical portion 161 and a protruding portion 162 that protrudes inward from the lower end of the cylindrical portion 161. The inner diameter of the cylindrical portion 161 is equal to or greater than the diameter of the outer peripheral surface of the rod portion 21 of the rod 20. The outer diameter of the cylindrical portion 161 is smaller than the diameter of the inner peripheral surface of the collar 17 and larger than the inner diameters of the elastic member 110 and the seal member 120.

[0026] The protruding portion 162 protrudes from the lower end of the cylindrical portion 161 around the entire circumference in a direction inclined toward the axial direction. The tip of the protruding portion 162 fits into the first groove 211 of the rod portion 21, thereby holding the first member 160 to the rod 20 so as not to move relative to the rod 20.

[0027] The second member 170 has a cylindrical first cylindrical portion 171 and a cylindrical second cylindrical portion 172 provided on the second side of the first cylindrical portion 171. The first cylindrical portion 171 and the second cylindrical portion 172 have the same inner diameter and are equal to or greater than the diameter of the outer peripheral surface of the rod portion 21. The outer diameter of the second cylindrical portion 172 is larger than the outer diameter of the first cylindrical portion 171. The outer diameter of the first cylindrical portion 171 is smaller than the inner diameter of the seal member 120. The outer diameter of the second cylindrical portion 172 is smaller than the diameter of the inner peripheral surface of the collar 17 and larger than the inner diameter of the seal member 120.

[0028] The restricting member 150 according to this embodiment is attached to the rod 20 with the inner periphery of the elastic member 110 sandwiched between the first member 160 and the second member 170. Then, the protruding portion 162 of the first member 160 fits into the first groove 211 of the rod portion 21, so that the first member 160 is held by the rod 20 so as not to move relative to the rod 20, and movement of the second member 170 toward the second side is restricted by the clip 180. As a result, the inner periphery of the elastic member 110 becomes a fixed end and the outer periphery becomes a free end.

[0029] (Function of second piston portion 100) Fig. 4 is an example of a cross-sectional view of the second piston portion 100 during the extension stroke, when the amount by which the rod 20 protrudes from the cylinder portion 10 (hereinafter, sometimes referred to as "protrusion amount") increases. Fig. 5 is an example of an enlarged view of portion V in Fig. 4. Fig. 6 is an example of a cross-sectional view of the second piston portion 100 during the extension stroke.

[0030] During the extension stroke, when the rod 20 protrudes more from the cylinder portion 10, the second piston portion 100 moves from a position on the first side of the collar 17 (the position shown in FIG. 2 ) to a position on the second side, and the seal member 120 enters the collar 17 and contacts the inner circumferential surface of the collar 17. This forms a high-pressure chamber in the space within the collar 17, where the pressure is higher than the pressure in the space within the second chamber Y2 on the first piston portion 30 side of the seal member 120 (in other words, the first side). Hereinafter, the space within the collar 17 on the first side of the seal member 120 may be referred to as the "third chamber Y3," and the space within the collar 17 on the second side of the seal member 120 may be referred to as the "fourth chamber Y4." The fourth chamber Y4 is the high-pressure chamber described above.

[0031] When the pressure in the fourth chamber Y4 increases and the force acting on the second-side end face 133 of the seal member 120 becomes greater than the force acting on the first-side portions of the seal member 120 and the elastic member 110, the seal member 120 bends the outer periphery of the elastic member 110. As a result, the opposing surface 131 of the seal member 120 comes into contact with the elastic member 110, and the elastic member 110 is sandwiched between the seal member 120 and the cylindrical portion 161 of the first member 160, as shown in Figures 4 and 5 .

[0032] 4 and 5 , a portion of the oil in the fourth chamber Y4 flows into the fifth chamber Y5, which is a space surrounded by the opposing surface 131 of the seal member 120, the inner circumferential surface of the convex portion 140, and the elastic member 110, via the concave portion 132 of the seal member 120. Then, as shown in FIG. 5 , a portion of the oil in the fifth chamber Y5 flows into the third chamber Y3 via the groove 141 formed in the convex portion 140 of the seal member 120. In this manner, a damping force is generated by the oil flowing into the third chamber Y3 via the groove 141. The groove 141 functions as an orifice that allows oil to flow from the fourth chamber Y4 to the third chamber Y3.

[0033] In the state shown in Figures 4 and 5, if the pressure in the fifth chamber Y5 further increases, the outer periphery of the elastic member 110 further bends, as shown in Figure 6, and the elastic member 110 moves away from the convex portion 140. This causes oil to flow from the fifth chamber Y5 to the third chamber Y3. In the state shown in Figure 6, a damping force is generated by oil flowing from the fourth chamber Y4 to the third chamber Y3 through the concave portion 132 of the seal member 120. In this way, even if the collar 17 is configured as a cylinder, by having the second piston portion 100 function as both the orifice shown in Figures 4 and 5 and the blow-off valve shown in Figure 6, it is possible to achieve both layout flexibility and damping characteristics.

[0034] In order to allow the elastic member 110 to separate from the convex portion 140 when the pressure in the fourth chamber Y4 becomes higher than the pressure in the third chamber Y3 by a predetermined pressure or more after the sealing member 120 has deflected the outer periphery of the elastic member 110, the flow path areas of the recessed portion 132 and the groove 141 (in other words, the cross-sectional areas cut along a plane perpendicular to the axial direction) are set as follows: In other words, when the opposing surface 131 and the convex portion 140 come into contact with the elastic member 110, the total flow path area formed by the groove 141 and the elastic member 110 is smaller than the total flow path area formed by the recessed portion 132 and the elastic member 110.

[0035] 7 is an example cross-sectional view of the second piston portion 100 during the compression stroke when the amount of protrusion of the rod 20 decreases. As shown in FIG. 7 , during the compression stroke when the amount of protrusion of the rod 20 from the cylinder portion 10 decreases, if the force acting on the first side portion of the seal member 120 becomes greater than the force acting on the second side end face 133 of the seal member 120, the seal member 120 moves toward the second side and abuts against the second cylindrical portion 172. When the seal member 120 moves toward the first side beyond the collar 17, oil flows through the outside of the seal member 120, so that the pressures in the spaces on the first and second sides of the seal member 120 become equal.

[0036] As described above, the shock absorber 2 includes the rod 20, a portion of which is inserted into the cylindrical cylinder 11, the first piston portion 30 fixed to the rod 20 and defining a space within the cylinder 11, and the cylindrical collar 17 disposed on the rod 20 side (i.e., the second side) of the first piston portion 30 within the cylinder 11. The shock absorber 2 also includes the second piston portion 100 fixed to the rod 20 coaxially with the first piston portion 30 and capable of entering the collar 17 to form a fourth chamber Y4, an example of a high-pressure chamber having a higher pressure than the first piston portion side, within the space within the collar 17. The second piston portion 100 includes an annular elastic member 110 having elasticity, a seal member 120 disposed on the opposite side of the elastic member 110 from the first piston portion 30 in the axial direction of the rod 20 and capable of contacting the inner circumferential surface of the collar 17, and a restricting member 150 that restricts axial movement of the elastic member 110 and the seal member 120. The sealing member 120 has a cylindrical base 130 and a protrusion 140 that protrudes annularly from the outer periphery of an opposing surface 131 of the base 130 that faces the elastic member 110 toward the elastic member 110 and is capable of contacting the outer periphery of the elastic member 110. The base 130 has a recess 132 formed inside the protrusion 140 that is recessed from the opposing surface 131 on the side opposite the elastic member 110, and the protrusion 140 has a groove 141 formed in at least a portion of the circumferential direction that connects the inside and outside.

[0037] Here, it is desirable for the shock absorber 2 to have a high damping force during the extension stroke. For example, this is because suppressing lift on the inner wheel side during cornering suppresses the occurrence of roll and contributes to improving ride comfort. According to the shock absorber 2, the second piston portion 100 forms a high-pressure chamber (in other words, the fourth chamber Y4) within the collar 17 during the extension stroke, so the damping force can be increased compared to, for example, a configuration that does not include the second piston portion 100.

[0038] On the other hand, if the damping force during the extension stroke is increased too much, the ride quality may become too hard, which may actually worsen the ride quality. According to the shock absorber 2, when the second piston portion 100 forms a high-pressure chamber within the collar 17 during the extension stroke, the groove 141 functions as an orifice that allows oil to flow from the fourth chamber Y4 to the third chamber Y3, so that the damping force can be prevented from becoming too high.

[0039] Furthermore, according to the shock absorber 2, these damping forces can be set by changing the flow path area of ​​the groove 141 and the recess 132, so that the damping force characteristics can be set with a high degree of freedom. Also, by configuring the second piston portion 100 with the elastic member 110, the seal member 120, and the restricting member 150, the shock absorber 2 that achieves the above-mentioned effects can be realized at low cost.

[0040] In the first embodiment, the restricting member 150 has a first member 160 and a second member 170 arranged side by side in the axial direction, and the elastic member 110 is sandwiched between the first member 160 and the second member 170. This makes it possible to restrict the axial movement of the elastic member 110, and to quickly switch from one of the compression stroke and the extension stroke to the other.

[0041] However, the elastic member 110 does not have to be sandwiched between the first member 160 and the second member 170. For example, the inner diameter of the elastic member 110 may be smaller than the inner diameter of the seal member 120 and larger than the inner diameter of the first cylindrical portion 171 of the second member 170, so that the elastic member 110 is movable between the first member 160 and the seal member 120.

[0042] <Second embodiment> Fig. 8 is a diagram showing an example of a schematic configuration of a second piston portion 200 according to a second embodiment. The second piston portion 200 according to the second embodiment differs from the second piston portion 100 according to the first embodiment in that it has a seal member 220 that corresponds to the seal member 120. Differences from the first embodiment will be described below. The same components in the first and second embodiments are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

[0043] The seal member 220 differs from the seal member 120 in that it has a symmetrical shape with respect to a plane perpendicular to the axial direction. That is, the seal member 220 has a base 230 corresponding to the base 130 according to the first embodiment, a protrusion 140, and a protrusion 240 that protrudes annularly from the outer periphery of an end face 233 on the second side of the base 230 toward the second side.

[0044] The convex portion 240 has a symmetrical shape to the convex portion 140 with respect to a plane perpendicular to the axial direction, and has a groove 241 extending in the radial direction so as to connect the inner portion and the outer portion of the convex portion 240.

[0045] The base 230 differs from the base 130 according to the first embodiment in that a plurality of (e.g., ten) recesses 232 recessed from an end face 233 toward the first side are formed in the circumferential direction in a region more inward than the protrusion 240. The recesses 232 are symmetrical to the recesses 132 with respect to a plane perpendicular to the axial direction. The base 230 is symmetrical with respect to a plane perpendicular to the axial direction.

[0046] The second piston portion 200 according to the second embodiment can achieve the same effects as those achieved by the second piston portion 100 according to the first embodiment described above. In addition, in the second piston portion 200, the seal member 220 has a symmetrical shape with respect to a plane perpendicular to the axial direction, so that the seal member 220 can be assembled without having to worry about the orientation of the seal member 220. As a result, the second piston portion 200 can improve ease of assembly.

[0047] 9 is a diagram showing an example of the state of the second piston portion 200 during the compression stroke, in which the amount of protrusion of the rod 20 decreases. During the compression stroke, even if the seal member 220 is present within the collar 17, the end face 233 of the seal member 220 abuts against the second cylindrical portion 172, and oil flows from the third chamber Y3 to the fourth chamber Y4 through the recess 232 of the seal member 220, thereby enabling a smooth transition from the extension stroke to the compression stroke.

[0048] <Third embodiment> Fig. 10 is a diagram showing an example of a schematic configuration of a second piston portion 300 according to a third embodiment. Fig. 11 is an example of a view of an elastic member 310 according to the third embodiment as viewed in the axial direction. The second piston portion 300 according to the third embodiment differs from the second piston portion 100 according to the first embodiment in that it has an elastic member 310 corresponding to the elastic member 110 and a regulating member 350 corresponding to the regulating member 150. Differences from the first embodiment will be described below. The same reference numerals are used for the same components in the first and third embodiments, and detailed description thereof will be omitted.

[0049] The restricting member 350 includes a first member 160 and a second member 370 corresponding to the second member 170. The second member 370 differs from the second member 170 according to the first embodiment in that a recess 373 recessed from the outer circumferential surface is formed around the entire circumference at the end of the first side. The axial size of the recess 373 is equal to or greater than the thickness of the elastic member 310. The second member 370 is also positioned so that the end surface on the first side can come into contact with the end surface on the second side of the first member 160. In other words, unlike the second piston portion 100 according to the first embodiment, the elastic member 310 is not sandwiched between the first member 160 and the second member 370.

[0050] In comparison with the elastic member 110 according to the first embodiment, the elastic member 310 has a plurality of protrusions 311 (eight in the example shown in FIG. 11 ) in the circumferential direction that protrude from the inner peripheral end toward the center. For example, the plurality of protrusions 311 can be formed at equal intervals in the circumferential direction. The radius of an imaginary circle formed by the tips of the plurality of protrusions 311 is equal to or less than the diameter of the outer peripheral surface 374 of the second member 370 at a portion where the recess 373 is formed. The plurality of protrusions 311 grip the outer peripheral surface 374, thereby fixing the elastic member 310 to the restricting member 350.

[0051] The second piston portion 300 according to the third embodiment can also achieve the same effects as those achieved by the second piston portion 100 according to the first embodiment described above. In addition, in the second piston portion 300, the elastic member 310 has a protrusion 311 that grips the outer peripheral surface 374 of the restricting member 350 and fixes the elastic member 310 to the restricting member 350. This allows the elastic member 310 and the restricting member 350 to be integrated in advance when assembling the second piston portion 300, so that the second piston portion 300 can improve ease of assembly.

[0052] <Fourth embodiment> Fig. 12 is a diagram showing an example of the schematic configuration of a shock absorber 400 according to a fourth embodiment. The shock absorber 400 according to the fourth embodiment differs from the shock absorber 2 according to the first embodiment in that it includes a cylinder portion 410 equivalent to the cylinder portion 10, and a third piston portion 500 that can prevent the pressure in the cylinder 11 from becoming too high during the compression stroke. The differences from the first embodiment will be described below. The same components in the first and fourth embodiments are designated by the same reference numerals, and detailed description thereof will be omitted.

[0053] Cylinder portion 410 differs from cylinder portion 10 in that it further includes a second collar 420 at the first end portion within cylinder 11. Second collar 420 is tubular with a bottom, and includes a cylindrical portion 421 and a blocking portion 422 that blocks the opening on the first side of cylindrical portion 421. Second collar 420 also includes a plurality of legs 423 that are provided on the first side of blocking portion 422.

[0054] The cylindrical portion 421 is capable of accommodating the third piston portion 500 therein and forms a gap between the cylindrical portion 421 and the cylinder 11. The leg portion 423 extends radially and toward the first side from an outer portion of the blocking portion 422. The portion extending toward the first side has an arc-like shape when viewed axially. Multiple leg portions 423 (e.g., three) are provided at equal intervals in the circumferential direction. The second collar 420 is fixed to the end of the first side inside the cylinder 11 by joining the leg portions 423 to the cylinder 11 by, for example, welding or adhesive. The leg portions 423 are located outside the valve 43, and the blocking portion 422 is located on the second side relative to the bottom valve 40. Since the second collar 420 only needs to accommodate the third piston portion 500, the thickness of each portion may be as small as possible.

[0055] The third piston portion 500 includes an annular elastic member 510 having elasticity, and a sealing member 520 that is arranged on the opposite side of the elastic member 510 from the first piston portion 30 in the axial direction (in other words, on the first side) and is capable of contacting the inner circumferential surface of the cylindrical portion 421 of the second collar 420. The third piston portion 500 also includes a first restricting member 550 that restricts axial movement of the elastic member 510 and the sealing member 520. The third piston portion 500 also includes an annular second restricting member 590 that restricts axial movement of the first piston portion 30.

[0056] The elastic member 510 is a ring-shaped plate made of, for example, metal. The inner diameter of the elastic member 510 is equal to or greater than the diameter of the outer circumferential surface of the lower attachment portion 22 of the rod 20, and the outer diameter of the elastic member 510 is smaller than the diameter of the inner circumferential surface of the cylindrical portion 421 of the second collar 420.

[0057] (Sealing member 520) The sealing member 520 is a cylindrical member made of, for example, metal or resin. More specifically, the sealing member 520 has a cylindrical base 530 and a convex portion 540 that protrudes in an annular shape from the outer periphery of an opposing surface 531 of the base 530 that faces the elastic member 510 toward the elastic member 510 (in other words, the second side).

[0058] The outer diameter of the base 530 is approximately equal to the diameter of the inner peripheral surface of the cylindrical portion 421 of the second collar 420. The base 530 has a plurality of (e.g., ten) recesses 532 formed in the circumferential direction at a position inside the protrusion 540, the recesses 532 being recessed from the opposing surface 531 toward the opposite side to the elastic member 510 (in other words, the first side).

[0059] The cross section of the protrusion 540 taken along a plane parallel to the axial direction is a rectangle with the radial direction as the longitudinal direction and the axial direction as the lateral direction. However, the inner peripheral surface of the protrusion 540 may be an inclined surface whose inner diameter increases toward the second side. This is because oil can flow more smoothly along the inclined surface.

[0060] Grooves 541 are formed in the protrusions 540, extending in the radial direction so as to connect the inner and outer regions of the protrusions 540. The grooves 541 are formed in positions that do not overlap with the recesses 532 in the circumferential direction. There may be one or more grooves 541. However, when cut along a plane perpendicular to the axial direction, the total cross-sectional area of ​​the one or more grooves 541 is smaller than the total cross-sectional area of ​​the multiple recesses 532.

[0061] (First Restricting Member 550) The first restricting member 550 has a first member 560 and a second member 570 arranged side by side in the axial direction. The first restricting member 550 can be, for example, a member made of metal or resin.

[0062] The first member 560 has a cylindrical portion 561 and a protruding portion 562 that protrudes inward from the upper end of the cylindrical portion 561. The inner diameter of the cylindrical portion 561 is equal to or greater than the diameter of the outer circumferential surface of the lower mounting portion 22 of the rod 20. The outer diameter of the cylindrical portion 561 is smaller than the outer diameter of the elastic member 510 and larger than the inner diameters of the elastic member 510 and the sealing member 520.

[0063] The protruding portion 562 protrudes from the upper end of the cylindrical portion 561 around the entire circumference in a direction inclined toward the axial direction. The tip of the protruding portion 562 fits into the first groove 221 of the lower attachment portion 22, thereby holding the first member 560 to the rod 20 so as not to move relative to the rod 20.

[0064] The second member 570 is an annular member. The inner diameter of the second member 570 is equal to or greater than the diameter of the outer peripheral surface of the lower mounting portion 22. The outer diameter of the second member 570 is smaller than the diameter of the inner peripheral surface of the cylindrical portion 421 of the second collar 420. Movement of the second member 570 toward the second side is restricted by means of, for example, press-fitting. Note that, as shown in FIG. 12 , movement of the second member 570 toward the second side may be restricted by a clip 580 fitted into a second groove 222 formed on the outer peripheral surface of the lower mounting portion 22.

[0065] (Function of the Third Piston 500) FIG. 13 is an example cross-sectional view of the third piston 500 during the compression stroke. During the compression stroke, when the third piston 500 moves from a position located on the second side of the second collar 420 (the position shown in FIG. 12 ) to the first side, the seal member 520 enters the second collar 420 and contacts the inner circumferential surface of the cylindrical portion 421 of the second collar 420. A high-pressure chamber is formed in the space within the cylindrical portion 421, where the pressure is higher than the pressure in the space within the first chamber Y1 on the first piston 30 side of the seal member 520 (in other words, the second side). Hereinafter, the space within the cylindrical portion 421 on the second side of the seal member 520 may be referred to as the "seventh chamber Y7," and the space within the cylindrical portion 421 on the first side of the seal member 520 may be referred to as the "eighth chamber Y8." The eighth chamber Y8 is the high-pressure chamber described above.

[0066] When the pressure in the eighth chamber Y8 increases and the force acting on the first-side end surface 533 of the seal member 520 becomes greater than the force acting on the second-side portions of the seal member 520 and the elastic member 510, the seal member 520 bends the outer periphery of the elastic member 510. As a result, as shown in FIG. 13 , the opposing surface 531 of the seal member 520 comes into contact with the elastic member 510, and the elastic member 510 is sandwiched between the seal member 520 and the cylindrical portion 561 of the first member 560.

[0067] 13 , a portion of the oil in the eighth chamber Y8 flows into the space surrounded by the opposing surface 531 of the seal member 520, the inner circumferential surface of the convex portion 540, and the elastic member 510 via the concave portion 532 of the seal member 520, and then flows out to the seventh chamber Y7 via the groove 541 formed in the convex portion 540 of the seal member 520. In this manner, a damping force is generated by the oil flowing out to the seventh chamber Y7 via the groove 541. The groove 541 functions as an orifice that allows oil to flow from the eighth chamber Y8 to the seventh chamber Y7.

[0068] 13, if the pressure in the space surrounded by the opposing surface 531 of the sealing member 520, the inner circumferential surface of the convex portion 540, and the elastic member 510 increases further, the outer circumferential portion of the elastic member 510 bends further, and the elastic member 510 moves away from the convex portion 540. This causes oil to flow into the seventh chamber Y7, generating a damping force. In this way, even if the plate thickness of the second collar 420 is configured to be the minimum, by having the third piston portion 500 function as both the orifice shown in FIG. 13 and the blow valve, it is possible to achieve both layout flexibility and damping characteristics.

[0069] In order to allow the elastic member 510 to separate from the convex portion 540 when the pressure in the eighth chamber Y8 becomes higher than the pressure in the seventh chamber Y7 by a predetermined pressure or more after the sealing member 520 has deflected the outer periphery of the elastic member 510, the flow path areas of the recessed portion 532 and the groove 541 (in other words, the cross-sectional areas cut along a plane perpendicular to the axial direction) are set as follows: In other words, when the opposing surface 531 and the convex portion 540 come into contact with the elastic member 510, the total flow path area formed by the groove 541 and the elastic member 510 is smaller than the total flow path area formed by the recessed portion 532 and the elastic member 510.

[0070] On the other hand, during the extension stroke, when the force acting on the second side portion of seal member 520 becomes greater than the force acting on end face 533 of seal member 520 on the first side, seal member 520 moves toward the first side and abuts against second member 570. When seal member 520 moves toward the second side beyond cylindrical portion 421 of second collar 420, oil flows through the outside of seal member 520, and the pressure in the space on the first side and the space on the second side of seal member 520 becomes equal.

[0071] According to the shock absorber 400, during the compression stroke, the third piston portion 500 forms a high-pressure chamber (in other words, the eighth chamber Y8) within the cylindrical portion 421 of the second collar 420, and therefore the damping force can be increased compared to, for example, a configuration that does not include the third piston portion 500. Furthermore, when the third piston portion 500 forms a high-pressure chamber within the cylindrical portion 421 of the second collar 420 during the compression stroke, the groove 541 functions as an orifice that allows oil to flow from the eighth chamber Y8 to the seventh chamber Y7, and therefore the damping force can be prevented from becoming too high.

[0072] Furthermore, according to shock absorber 400, these damping forces can be set by changing the flow path area of ​​groove 541 and recess 532, so that the damping force characteristics can be set with a high degree of freedom. Also, by configuring third piston portion 500 with elastic member 510, seal member 520, and first restricting member 550, shock absorber 400 that achieves the above-mentioned effects can be realized at low cost.

[0073] REFERENCE SIGNS LIST 1...suspension device, 2,400...shock absorber, 3...coil spring, 10...cylinder portion, 11...cylinder, 17...collar, 20...rod, 30...first piston portion, 100, 200, 300...second piston portion, 110, 310...elastic member, 120, 220...sealing member, 130, 230...base portion, 131...opposing surface, 132, 232...recessed portion, 140, 240...convex portion, 141, 241...groove, 150, 350...regulating member, 160...first member, 170, 370...second member, 311...projection portion, 374...outer peripheral surface, 420...second collar (an example of a collar), 500...third piston portion (an example of a second piston portion), Y1...first chamber, Y2...second chamber, Y3...third chamber, Y4...fourth chamber, Y5...fifth chamber

Claims

1. a rod partially inserted into a cylindrical cylinder; a first piston portion fixed to the rod and defining a space within the cylinder; a cylindrical collar disposed inside the cylinder closer to the rod than the first piston portion; a second piston portion that is fixed to the rod coaxially with the first piston portion and that can enter the collar to form a high-pressure chamber in a space within the collar, the high-pressure chamber having a pressure higher than that of the first piston portion; Equipped with The second piston portion is an annular elastic member having elasticity; a seal member that is disposed on the opposite side of the first piston portion with respect to the elastic member in the axial direction of the rod and that is capable of contacting an inner circumferential surface of the collar; a restricting member that restricts movement of the elastic member and the sealing member in the axial direction; and the sealing member has a cylindrical base and a protrusion that protrudes annularly from an outer periphery of a surface of the base that faces the elastic member toward the elastic member and is capable of contacting the outer periphery of the elastic member; The base portion has a recess formed inside the protrusion, the recess being recessed from the opposing surface toward the opposite side to the elastic member, The protrusion has a groove formed in at least a portion in the circumferential direction, the groove connecting the inside and the outside, a flow path for a damping medium that is connected to a space surrounded by the opposing surface of the seal member, the inner circumferential surface of the convex portion, and the elastic member is provided between the restricting member and the seal member; Buffer device.

2. At least one of the recess and the groove is formed in the sealing member, when the opposing surface and the convex portion contact the elastic member, a total flow path area formed by the groove and the elastic member is smaller than a total flow path area formed by the concave portion and the elastic member; The shock absorber according to claim 1 .

3. The sealing member has a symmetrical shape with respect to a plane perpendicular to the axial direction. The shock absorber according to claim 1 .

4. the elastic member further has a protrusion that protrudes from an end portion on the inner periphery toward the center and grips an outer periphery of the regulating member to fix the elastic member to the regulating member; The shock absorber according to claim 1 .

5. The restricting member has a first member and a second member arranged side by side in the axial direction, The elastic member is sandwiched between the first member and the second member. The shock absorber according to claim 1 .

6. The shock absorber according to any one of claims 1 to 5, and a coil spring disposed outside the shock absorber. A suspension device comprising:

7. a rod whose part is inserted into a bottomed cylindrical cylinder having a bottom portion and a cylindrical portion; a first piston portion fixed to the rod and defining a space within the cylinder; a cylindrical collar with a bottom that is disposed on the bottom portion so as to open toward the first piston portion; a second piston portion that is fixed to the rod coaxially with the first piston portion and that can enter the collar to form a high-pressure chamber in a space within the collar, the high-pressure chamber having a pressure higher than that of the first piston portion; Equipped with The second piston portion is an annular elastic member having elasticity; a seal member that is disposed on the opposite side of the first piston portion with respect to the elastic member in the axial direction of the rod and that is capable of contacting an inner circumferential surface of the collar; a restricting member that restricts movement of the elastic member and the sealing member in the axial direction; and the sealing member has a cylindrical base and a protrusion that protrudes annularly from an outer periphery of a surface of the base that faces the elastic member toward the elastic member and is capable of contacting the outer periphery of the elastic member; The base portion has a recess formed inside the protrusion, the recess being recessed from the opposing surface toward the opposite side to the elastic member, The protrusion has a groove formed in at least a portion in the circumferential direction, the groove connecting the inside and the outside, Between the rod and the seal member, there is a flow path for a damping medium that is connected to a space surrounded by the opposing surface of the seal member, the inner circumferential surface of the convex portion, and the elastic member. Buffer device.