Buffer device and suspension device

Abstract

To provide a buffer device or the like that enables size reduction.SOLUTION: Provided is a buffer device comprising: a first valve disposed on a first communication passage connecting a first chamber and a second chamber, the first and second chambers being partitioned by a piston retained on a rod, in which the first communication passage is opened when a second pressure in the second chamber is higher than a first pressure in the first chamber, and the first communication passage is closed when the first pressure is higher than the second pressure; a second valve provided on a second communication passage formed around the rod and connecting the first chamber and the second chamber, in which the second communication passage is closed when the second pressure is higher than the first pressure, and the second communication passage is opened when the first pressure is higher than the second pressure, the second valve being elastically deformed to increase a volume of a back pressure chamber that generates back pressure against the first valve; a restriction part that stores the second valve, forms the back pressure chamber together with the second valve, and restricts elastic deformation of the second valve; and a housing having a seating part which is a portion where the second valve is seated and seals a gap with the second valve.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] For example, the pressure buffer device described in Patent Document 1 includes a rod inserted into a cylinder that contains liquid and movable axially relative to the cylinder, and a piston connected to the rod that divides the space within the cylinder into a first liquid chamber and a second liquid chamber that contain liquid. The pressure buffer device described in Patent Document 1 also includes a flow path forming portion that forms a flow path for liquid between the first liquid chamber and the second liquid chamber, a valve portion that opens and closes the flow path in the flow path forming portion to generate a damping force, and a damping force changing portion that has an inflow portion into which liquid flows and changes the damping force generated by the valve portion depending on the pressure of the liquid in the inflow portion. The damping force changing portion also includes a pressure changing portion that changes the pressure of the liquid in the inflow portion by deforming or displacing, a support portion that supports the pressure changing portion, and an inflow forming portion that holds the support portion with a crimped portion and forms the inflow portion together with the support portion. The damping force changing portion also has a filter that is provided on the liquid flow path to the inlet portion and that collects foreign matter that gets mixed into the liquid, and also has a filter portion that is held in the inlet forming portion together with the support portion by the crimping portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6539009 Summary of the Invention [Problem to be solved by the invention]

[0004] The device described in Patent Document 1 has room for improvement in terms of miniaturization. An object of the present invention is to provide a shock absorber or the like that can be made smaller. [Means for solving the problem]

[0005] The present invention, which was completed with the above object in mind, is a shock absorber comprising: a first valve that is disposed in a first communication passage that communicates a first chamber and a second chamber that are partitioned by a piston held by a rod, and that opens the first communication passage when a second pressure that is the pressure in the second chamber is higher than a first pressure that is the pressure in the first chamber, and closes the first communication passage when the first pressure is higher than the second pressure; a second valve that is disposed in a second communication passage that is formed around the rod and communicates the first chamber and the second chamber, and that closes the second communication passage when the second pressure is higher than the first pressure, and that elastically deforms to increase the volume of a back pressure chamber that generates back pressure against the first valve, and that opens the second communication passage when the first pressure is higher than the second pressure; a restriction portion that accommodates the second valve and forms the back pressure chamber together with the second valve, and that restricts the elastic deformation of the second valve; and a housing that has a seat portion on which the second valve seats and that provides a seal between the second valve and the housing. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a shock absorber or the like that can be made smaller in size. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram showing an example of a schematic configuration of a suspension device according to a first embodiment. [Figure 2] 3 is a diagram showing an example of a cross section of a piston portion and a damping force change portion according to the first embodiment. FIG. [Figure 3] FIG. 2 is a diagram illustrating an example of a schematic configuration of a diaphragm member. [Figure 4] FIG. 2 is a diagram illustrating an example of a schematic configuration of a support spring. [Figure 5] 4 is a diagram showing an example of a partial cross section of a damping force changing portion; FIG. [Figure 6] 5A to 5C are explanatory diagrams illustrating the operation of the piston portion and the bottom portion during the compression stroke and the extension stroke. [Figure 7] 10A and 10B are diagrams illustrating an example of the operation of the damping force change unit during an extension stroke. [Figure 8] 10A and 10B are diagrams illustrating an example of the operation of the damping force changing unit during a compression stroke. [Figure 9] 10A and 10B are diagrams illustrating an example of a rubber portion according to a modified example. [Figure 10] 10A and 10B are diagrams illustrating an example of a holding structure according to a modified example. [Figure 11] 10A and 10B are diagrams showing an example of a modified seal of the pressure adjustment chamber. [Figure 12] FIG. 10 is a diagram showing an example of a second valve according to a modified example. [Figure 13] FIG. 10 is a diagram showing an example of a cross section of a shock absorber according to a second embodiment. [Figure 14] 10A and 10B are diagrams illustrating an example of a housing according to a modified example of the housing according to the second embodiment. [Figure 15] FIG. 10 is a diagram showing an example of a cross section of a shock absorber according to a third embodiment. [Figure 16] FIG. 10 is a diagram showing an example of a cross section of a shock absorber according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[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 a schematic configuration of a suspension system 1 according to the first embodiment. The suspension system 1 is a suspension used in four-wheeled vehicles such as passenger cars, and as shown in Fig. 1, comprises a hydraulic shock absorber 2 and a coil spring 3 arranged on the outside of the shock absorber 2. The suspension system 1 also comprises 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 below, 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 device 1 also includes a vehicle body side bracket 6 for attaching the suspension device 1 to a vehicle, a wheel side bracket 7 for attaching the suspension device 1 to a wheel, and a dust cover 8 that covers at least a portion of the cylinder portion 10 and the rod 20. Hereinafter, the axial direction of the rod 20 may be simply referred to as the "axial direction." Furthermore, the first axial side (lower side in FIG. 1) and the second axial side (upper side in FIG. 1) may be simply referred to as the "first side" and the "second side," respectively. Furthermore, the direction intersecting the axial direction (for example, the perpendicular direction) may be simply 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."

[0010] 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 whose second end protrudes from the cylinder portion 10 and whose first end is inserted into the cylinder portion 10. The shock absorber 2 also includes a piston portion 30 provided at the first end of the rod 20, a damping force changing portion 40 that adjusts the damping force generated by the piston portion 30, and a bottom portion 60 provided at the first end of the cylinder portion 10.

[0011] [Cylinder part 10] The cylinder section 10 includes a thin-walled cylindrical cylinder 11, a thin-walled cylindrical outer cylinder 12 provided on the outside of the cylinder 11, and a bottom cover 13 that closes a first end of the outer cylinder 12. The cylinder 11 and the outer cylinder 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 between the outer peripheral surface of the cylinder 11 and the inner peripheral surface of the outer cylinder 12. The reservoir chamber R is filled with oil on the first side and gas on the second side.

[0012] The cylinder portion 10 also includes a rod guide 14 that movably supports the rod 20, a bump stopper cap 15 attached to the second end of the outer tube 12, and a sealing member 16 that prevents oil from leaking from within the cylinder portion 10 and prevents foreign matter from entering the cylinder portion 10.

[0013] [Rod 20] The rod 20 is a solid or hollow rod-shaped member. The rod 20 has a first-side mounting portion 21 provided on a first side, a second-side mounting portion 22 provided on a second side, and a shaft portion 23 between the first-side mounting portion 21 and the second-side mounting portion 22. The first-side mounting portion 21 and the second-side mounting portion 22 each have a spiral groove cut into their outer surface to function as a bolt. The first-side mounting portion 21 has a main body portion 211 provided on the second side and a protrusion portion 212 protruding from the end of the main body portion 211 on the first side toward the first side. The main body portion 211 is formed with a piston bolt 213 (see FIG. 2) that holds the piston portion 30 and a first valve 41 and a support member 43 (described later) of the damping force change unit 40. The protrusion portion 212 is formed with a housing bolt 214 (see FIG. 2) that holds a second valve 45 and a housing 50 (described later) of the damping force change unit 40. The second side mounting portion 22 holds the vehicle body side bracket 6, and the vehicle body side bracket 6 is connected to the vehicle body, for example.

[0014] 2, the rod 20 has a bypass passage 25 that allows oil to circulate between the second chamber Y2 and the first chamber Y1, bypassing the piston portion 30. The bypass passage 25 is composed of a groove extending in the radial direction formed at the first-side end of the shaft portion 23, and a groove extending in the axial direction formed on the second side of the spiral groove in the first-side mounting portion 21 (in other words, the piston bolt 213 (see FIG. 2)).

[0015] [Bottom part 60] As shown in FIG. 1, the bottom portion 60 includes a valve body 61 having a plurality of oil passages passing through in the axial direction, a valve 62 provided on a first side of the valve body 61, and a valve 63 provided on a second side of the valve body 61. The valve body 61 of the bottom portion 60 separates the first chamber Y1 and the reservoir chamber R.

[0016] [Piston part 30] FIG. 2 is a diagram showing an example of a cross section of the piston portion 30 and the damping force change portion 40 according to the first embodiment. FIG. 3 is a diagram showing an example of a schematic configuration of the diaphragm member 42. As shown in FIG. FIG. 4 is a diagram showing an example of a schematic configuration of the support spring 47. As shown in FIG. FIG. 5 is a diagram showing an example of a partial cross section of the damping force changer 40. As shown in FIG.

[0017] 2, the piston portion 30 includes a piston 31, an extension side damping valve portion 321 provided on a first side of a cylindrical portion 311 (described later) of the piston 31, and a compression side damping valve portion 322 provided on a second side of the piston 31. The piston portion 30 also includes a first valve stopper 340 and a second valve stopper 353.

[0018] Piston 31 has a columnar portion 311 formed in a substantially cylindrical shape and having a plurality of oil passages, which will be described later, formed therein, and a cylindrical portion 312 provided on a first side of columnar portion 311. The piston 31 contacts the cylinder 11 via a sliding portion provided on the radially outer side to reduce frictional resistance. The piston portion 30 divides the space in the cylinder 11 filled with oil into a first chamber Y1 on the first side and a second chamber Y2 on the second side.

[0019] Furthermore, the piston 31 has a mounting hole 33R through which the rod 20 passes, and an extension-side oil passage 331 and a compression-side oil passage 332 formed radially outward from the mounting hole 33R. A plurality of extension-side oil passages 331 and a plurality of compression-side oil passages 332 are provided at approximately equal intervals in the circumferential direction. The extension-side oil passage 331 and the compression-side oil passage 332 each enable oil to flow between the first chamber Y1 and the second chamber Y2.

[0020] The extension side damping valve portion 321 can be configured by a plurality of elastic, substantially disk-shaped plates. The extension side damping valve portion 321 always opens the first side of the compression side oil passage 332, and opens and closes the first side of the extension side oil passage 331. The compression side damping valve portion 322 can be configured by a plurality of elastic, substantially disk-shaped plates. The compression side damping valve portion 322 always opens the second side of the extension side oil passage 331, and opens and closes the second side of the compression side oil passage 332.

[0021] The first valve stopper 340 has a mounting hole 340R through which the rod 20 passes. The second valve stopper 353 has a first outer diameter portion 353a having a predetermined outer diameter and a second outer diameter portion 353b having an outer diameter larger than that of the first outer diameter portion 353a. The second valve stopper 353 is provided so that the first outer diameter portion 353a fits inside the cylindrical portion 312 of the piston 31. When the extension side damping valve portion 321 deforms, the second valve stopper 353 prevents the extension side damping valve portion 321 from deforming more than a certain amount. The second valve stopper 353 also functions as a valve seat for the first valve 41, which will be described later.

[0022] The second valve stopper 353 also has an attachment hole 353R that extends in the axial direction and has an inner diameter that allows the first side attachment portion 21 of the rod 20 to pass through. The second valve stopper 353 also has a recess 353c that opens toward the first valve 41, which will be described later. The first side mounting portion 21 of the second valve stopper 353 is fitted into the mounting hole 353R, and the extension side damping valve portion 321 is sandwiched between the first side mounting portion 21 and the piston 31. The recess 353c of the second valve stopper 353 is a space that communicates with the bypass passage 25.

[0023] [Damping force changing unit 40] 2, the damping force change unit 40 includes a first valve 41 that controls the flow of oil in the bypass path 25, a throttle member 42 that throttles the flow of oil in the bypass path 25, a support member 43 that sandwiches the first valve 41 and the throttle member 42 between itself and a second valve stopper 353, and a nut 44 that is tightened around the piston bolt 213 of the rod 20. The damping force change unit 40 also includes a second valve 45 that forms the pressure adjustment chamber 100, a housing 50 that accommodates the second valve 45, a spool 46 that is slidably disposed relative to the housing 50, and a support spring 47 that applies a spring force to the spool 46. The damping force change unit 40 also includes a first collar 48 that is disposed between the housing 50 and the second valve 45, a second collar 49 that is disposed between the second valve 45 and the main body 211 of the rod 20, and a nut 55 that is tightened around the housing bolt 214 of the rod 20.

[0024] The first valve 41 covers the recess 353c of the second valve stopper 353. When the first valve 41 is deformed and no longer covers the recess 353c, it opens the recess 353c and allows oil in the second chamber Y2 to flow to the first chamber Y1 side through the bypass path 25 and the recess 353c.

[0025] As shown in Fig. 3, the throttle member 42 is elastic and has an annular shape. The throttle member 42 has an opening 42H on the radially inner side, through which the first-side mounting portion 21 of the rod 20 passes, and an orifice 42S cut outward from the opening 42H. The throttle member 42, together with the first valve 41, is provided between the second valve stopper 353 and the support member 43. As shown in Fig. 5, the orifice 42S is provided so as to extend to the outside of the support member 43. The orifice 42S is connected to the first end of the bypass path 25. In this embodiment, two orifices 42S are provided in the circumferential direction, but the number, length, slit width, etc. can be set as appropriate.

[0026] 5, the support member 43 has a first cylindrical portion 431 provided on the first side and a second cylindrical portion 432 provided on the second side. The first cylindrical portion 431 and the second cylindrical portion 432 have the same inner diameter and are larger than the diameter of the first-side mounting portion 21 of the rod 20, and the first-side mounting portion 21 of the rod 20 passes through the inside of the first cylindrical portion 431. The outer diameter of the first cylindrical portion 431 is larger than the outer diameter of the second cylindrical portion 432. The outer diameter of the first cylindrical portion 431 is smaller than the inner diameter of a cylindrical portion 461 (described later) of the spool 46, and the support member 43 is disposed inside the spool 46.

[0027] The nut 44 is tightened onto the piston bolt 213 formed on the first side mounting portion 21 of the rod 20 to determine the positions of the support member 43, the first valve 41, etc. The outer diameter of the nut 44 is smaller than the inner diameter of a cylindrical portion 51 of the housing 50, which will be described later, and the nut 44 is disposed inside the housing 50.

[0028] The second valve 45 is a member formed into a circular ring shape from a thin metal plate. The inner diameter of the second valve 45 is larger than the outer diameter of the protruding portion 212 of the first side mounting portion 21 of the rod 20 and smaller than the outer diameter of the main body portion 211. The outer diameter of the second valve 45 is smaller than the inner diameter of a cylindrical portion 51 (described later) of the housing 50, and the second valve 45 is disposed inside the housing 50.

[0029] The spool 46 has a cylindrical portion 461 and an annular portion 462 that protrudes inward from the second end of the cylindrical portion 461. The inner diameter of the cylindrical portion 461 is larger than that of a cylindrical portion 51 of the housing 50 , which will be described later, and the housing 50 is disposed inside the cylindrical portion 461 .

[0030] The inner diameter of the annular portion 462 is larger than the outer diameter of the second cylindrical portion 432 of the support member 43 and smaller than the outer diameter of the first cylindrical portion 431. The annular portion 462 is disposed on the second side of the first cylindrical portion 431 of the support member 43 and outside the second cylindrical portion 432. The annular portion 462 has a plurality of axial through holes 463 formed in the circumferential direction. Furthermore, the annular portion 462 has, outside the through holes 463, a first protruding portion 465 protruding toward the first side and a second protruding portion 466 protruding toward the second side.

[0031] The second protrusion 466 of the spool 46 contacts the outer periphery of the first valve 41 on the second side, and the first protrusion 465 of the spool 46 contacts the outer periphery of the support spring 47 on the first side. The spool 46 applies a force to the first valve 41 to press the first valve 41 against the end of the second valve stopper 353 on the first side. The annular portion 462 of the spool 46 does not necessarily have to have a portion located inside the first protruding portion 465 and the second protruding portion 466.

[0032] As shown in Fig. 4, the support spring 47 is formed in a ring shape and has a plurality of protrusions 47a protruding outward from its outer periphery. The inner diameter of the support spring 47 is larger than the outer diameter of the second cylindrical portion 432 of the support member 43 and smaller than the outer diameter of the first cylindrical portion 431. The support spring 47 is disposed on the second side of the first cylindrical portion 431 of the support member 43 and on the first side of the annular portion 462 of the spool 46. As shown in Fig. 5, the support spring 47 biases the spool 46 toward the second side.

[0033] The first collar 48 and the second collar 49 are annular members. The inner diameters of the first collar 48 and the second collar 49 are larger than the outer diameter of the protrusion 212 of the first side mounting portion 21 of the rod 20, and the outer diameters of the first collar 48 and the second collar 49 are smaller than the outer diameter of the main body 211 of the first side mounting portion 21 of the rod 20.

[0034] The housing 50 is a concave member formed by, for example, pressing a thin metal plate. As shown in Fig. 5, the housing 50 has a cylindrical portion 51 and an annular portion 52 that protrudes inward from a first end of the cylindrical portion 51. The inner diameter of the cylindrical portion 51 is larger than the outer diameter of the nut 44 and the outer diameter of the second valve 45. Rubber is baked onto the entire surface of the cylindrical portion 51. A portion of the rubber baked onto the outer peripheral surface of the cylindrical portion 51 protrudes so that a cross section of the rubber along a plane parallel to the axial direction forms an arc, forming a seal portion 511 that seals against the inner peripheral surface of the spool 46. For example, a plurality of seal portions 511 (two in FIG. 5) may be provided in the axial direction.

[0035] The inner diameter of the annular portion 52 is larger than the outer diameter of the protruding portion 212 of the first side mounting portion 21 of the rod 20, and smaller than the outer diameters of the first collar 48 and the second collar 49. The annular portion 52 has a plurality of axial through holes 521 formed in the circumferential direction. The annular portion 52 has a rubber portion 522, with rubber baked onto the outer periphery of the second side surface. The rubber portion 522 is provided in an annular shape so as to be in contact with the entire outer periphery of the second valve 45. For example, the radial size of the area where the rubber portion 522 and the second valve 45 contact each other can be 1 / 30 to 1 / 10 of the radial size of the second valve 45. For example, the axial size of the rubber portion 522 can be the same as the axial size of the first collar 48.

[0036] The second collar 49, the second valve 45, the first collar 48, and the housing 50 are held to the rod 20 by tightening a nut 55 onto the housing bolt 214 with the protrusion 212 of the first side mounting portion 21 of the rod 20 passing through the inside of the second collar 49, the second valve 45, the first collar 48, and the housing 50. The nut 44, the second valve 45, the second collar 49, the housing 50, the rod 20, etc. form a pressure adjustment chamber 100.

[0037] In the damping force changer 40 configured as described above, the second valve 45 is supported by the first collar 48 and the second collar 49, with its inner circumferential portion sandwiched between the first collar 48 and the second collar 49. The first side surface of the second valve 45 receives the pressure of the first chamber Y1, and the second side surface receives the pressure of the pressure adjustment chamber 100. When the pressure in the pressure adjustment chamber 100 is higher than the pressure in the first chamber Y1, the second valve 45 is deformable until its outer circumferential portion comes into contact with the rubber portion 522 of the housing 50 and its first side surface comes into contact with the second side surface of the annular portion 52 of the housing 50. On the other hand, when the pressure in the first chamber Y1 is higher than the pressure in the pressure adjustment chamber 100, the second valve 45 is deformable so that its outer circumferential portion moves away from the rubber portion 522. In this way, the second valve 45 changes the volume of the pressure adjustment chamber 100 by deforming during the extension stroke and the compression stroke, and blocks or allows the flow of oil between the pressure adjustment chamber 100 and the first chamber Y1 by blocking or opening the through hole 521 in the annular portion 52 of the housing 50.

[0038] Next, the operation of the shock absorber 2 will be described. FIG. 6 is a diagram illustrating the operation of the piston portion 30 and the bottom portion 60 during the compression stroke and the extension stroke.

[0039] 6, during the compression stroke in which the rod 20 moves toward the first side relative to the cylinder 11 as indicated by the white arrow, the oil pressure in the first chamber Y1 rises. This opens the compression side damping valve portion 322 that blocks the compression side oil passage 332, and oil flows into the second chamber Y2 through the compression side oil passage 332 as indicated by arrow A. This flow of oil from the first chamber Y1 to the second chamber Y2 is throttled by the compression side damping valve portion 322, and damping force during the compression stroke of the shock absorber 2 is obtained. Furthermore, the oil in the first chamber Y1, whose pressure has increased due to the axial movement of the piston 31 toward the first side, opens the valve 62 in the bottom portion 60. Then, the oil in the first chamber Y1 flows out into the reservoir chamber R, as shown by arrow B.

[0040] 6, during the extension stroke in which the rod 20 moves toward the second side relative to the cylinder 11 as indicated by the white arrow, the first chamber Y1 becomes short of oil by that volume, causing negative pressure. As a result, the oil in the second chamber Y2 passes through the extension-side oil passage 331 of the piston portion 30, opens the extension-side damping valve portion 321 that closes the extension-side oil passage 331, and flows into the first chamber Y1 as indicated by arrow C. The flow of oil from the second chamber Y2 to the first chamber Y1 is throttled by the extension-side damping valve portion 321 of the piston portion 30, and the damping force during the extension stroke of the shock absorber 2 is obtained. Furthermore, when the piston 31 moves to the second side, the oil in the reservoir chamber R opens the valve 63 as shown by the arrow D and flows into the first chamber Y1.

[0041] FIG. 7 is a diagram showing an example of the operation of the damping force changing unit 40 during the extension stroke. When the rod 20 moves with a small amplitude, during the extension stroke, oil that has flowed into the bypass path 25 from the second chamber Y2 (see FIG. 6) passes through the orifice 42S of the throttle member 42 and the through-hole 463 of the annular portion 462 of the spool 46, and then flows into the pressure adjustment chamber 100. At this time, in the pressure adjustment chamber 100, the second valve 45 bends toward the second surface of the annular portion 52 of the housing 50, increasing the volume of oil that can be accommodated, making it difficult for the oil pressure in the pressure adjustment chamber 100 to increase. Therefore, the force that the spool 46, which is provided on the pressure adjustment chamber 100 side, applies to the first valve 41 toward the second valve stopper 353 also becomes smaller. Then, the first valve 41 opens the recess 353c of the second valve stopper 353. As a result, the oil flowing through the bypass path 25 flows out from the recess 353c of the second valve stopper 353 into the first chamber Y1. In this way, when the rod 20 moves with a small amplitude, a flow of oil occurs that bypasses the extension-side oil passage 331 of the piston portion 30 (see FIG. 6). Therefore, when the rod 20 moves with a small amplitude, during the extension stroke, in addition to the oil flow in the extension-side oil passage 331 of the piston portion 30 (see Figure 6), oil also flows through the bypass passage 25, and the damping force generated in the piston portion 30 becomes smaller.

[0042] On the other hand, when the rod 20 moves with a large amplitude, during the extension stroke, oil that has flowed from the second chamber Y2 (see FIG. 6) into the bypass path 25 passes through the orifice 42S of the throttle member 42 and the through-hole 463 of the annular portion 462 of the spool 46, and then flows into the pressure adjustment chamber 100. When the rod 20 moves with a large amplitude, the second valve 45 immediately bends in the pressure adjustment chamber 100 to the second-side surface of the annular portion 52 of the housing 50, and the contact pressure of the outer periphery of the second valve 45 against the rubber portion 522 of the housing 50 increases, causing the oil in the pressure adjustment chamber 100 to become pressurized. Therefore, the force of the spool 46, which is provided on the pressure adjustment chamber 100 side, pressing the first valve 41 toward the second valve stopper 353 increases. Then, the first valve 41 blocks the recess 353c of the second valve stopper 353. Therefore, when the rod 20 moves with a large amplitude, during the extension stroke, oil does not flow from the second chamber Y2 to the first chamber Y1 via the bypass path 25, and only oil flows through the extension-side oil path 331 of the piston portion 30 (see Figure 6), so the damping force generated in the piston portion 30 becomes large.

[0043] FIG. 8 is a diagram showing an example of the operation of the damping force changing section 40 during the compression stroke. During the compression stroke, the pressure in the first chamber Y1 becomes higher than the pressure in the pressure adjustment chamber 100. As a result, the oil that has passed through the through-hole 521 in the annular portion 52 of the housing 50 bends the outer circumferential portion of the second valve 45 toward the second side, starting from the inner circumferential portion. As a result, the second valve 45 separates from the rubber portion 522 of the housing 50, and the oil flows from the first chamber Y1 into the pressure adjustment chamber 100.

[0044] As described above, when the rod 20 moves slightly, for example, when the vehicle is traveling on a rough road, the shock absorber 2 reduces the damping force, thereby improving the ride comfort of the vehicle. On the other hand, when the rod 20 moves significantly, for example, when the vehicle is traveling around a curve, the shock absorber 2 increases the damping force, thereby improving the handling stability of the vehicle.

[0045] As described above, the shock absorber 2 includes the first valve 41, which is disposed on the first communication passage (e.g., the bypass passage 25 and the recess 353c) that communicates between the first chamber Y1 and the second chamber Y2 defined by the piston 31 held by the rod 20, and which opens the first communication passage when the second pressure, which is the pressure in the second chamber Y2, is higher than the first pressure, which is the pressure in the first chamber Y1, and closes the first communication passage when the first pressure is higher than the second pressure. The shock absorber 2 also includes the second valve 45, which is disposed on the second communication passage (e.g., the orifice 42S, the pressure adjustment chamber 100, the through-hole 521) that is formed around the rod 20 and communicates between the first chamber Y1 and the second chamber Y2, and which closes the second communication passage when the second pressure is higher than the first pressure, elastically deforms to increase the volume of the pressure adjustment chamber 100 (an example of a back pressure chamber) that generates back pressure against the first valve 41, and opens the second communication passage when the first pressure is higher than the second pressure. The shock absorber 2 also includes a housing 50 having a circular portion 52 (an example of a regulating portion) of the housing 50 that accommodates the second valve 45 and forms a pressure adjustment chamber 100 together with the second valve 45, and that regulates the elastic deformation of the second valve 45, and a rubber portion 522 (an example of a seating portion) that is the portion where the second valve 45 seats and seals the gap between the second valve 45 and the housing 50.

[0046] According to the shock absorber 2 configured as described above, the housing 50 that accommodates the second valve 45 has the annular portion 52 and the rubber portion 522, and therefore can be made smaller than a configuration that separately includes a member that accommodates the second valve 45, a member that restricts the elastic deformation of the second valve 45, a member that seals the gap with the second valve 45, etc.

[0047] The shock absorber 2 also defines the pressure adjusting chamber 100 and further includes a spool 46 (an example of a sliding member) that is slidably fitted into the housing 50, and the housing 50 includes a seal portion 511 (an example of a sliding seal portion) that seals the space between the housing 50 and the spool 46. This simplifies the shock absorber 2 compared to a configuration that includes a seal member such as an O-ring that seals the space between the housing 50 and the spool 46.

[0048] The housing 50 has an annular portion 52 (an example of a main body) formed of metal, and rubber that is baked onto the annular portion 52 to form the rubber portion 522. This simplifies the configuration of the housing 50 compared to a configuration that includes a seal member that seals the gap with the second valve 45.

[0049] Furthermore, because the inner peripheral portion of the second valve 45 is sandwiched between the first collar 48 and the second collar 49, there is no need to provide a member (such as a leaf spring) that applies force to the second valve 45 to suppress axial movement of the second valve 45. As a result, the axial size of the shock absorber 2 can be reduced.

[0050] Furthermore, the first side mounting portion 21 of the rod 20 has a protruding portion 212 with an outer diameter smaller than that of the main body portion 211, and the second valve 45 and the second collar 49 are disposed outside the protruding portion 212. This allows, for example, the area of ​​the surface of the second valve 45 that receives the oil pressure of the pressure adjustment chamber 100 to be increased.

[0051] In addition, the spool 46 has an annular portion 462 whose inner diameter is larger than the outer diameter of the second cylindrical portion 432 of the support member 43 and smaller than the outer diameter of the first cylindrical portion 431, making it easy to align the center line of the cylindrical portion 461 of the spool 46 with the center line of the rod 20, making it easier to assemble the spool 46. Furthermore, since the housing 50 can be formed by pressing a thin metal plate, it can be made less expensive than a configuration that uses a member that requires cutting, for example.

[0052] (Modification of the rubber part 522 of the housing 50) FIG. 9 is a diagram showing an example of a rubber part 220 according to a modified example. In the shock absorber 2 described above, the rubber part 522 of the annular part 52 of the housing 50 may have the configuration of the rubber part 220 according to the modified example shown in FIG. The rubber part 220 has a base end 221 baked onto the outer periphery of the annular part 52 of the housing 50, and an inclined part 222 that protrudes outward from the inner periphery of the base end 221 in a direction inclined toward the axial direction along the entire circumference. The outer diameter of the tip of the inclined part 222 is equal to or smaller than the outer diameter of the second valve 45. The rubber portion 220 according to the modified example configured as described above improves the sealing performance between the second valve 45 and the rubber portion 220 of the housing 50 during the extension stroke, thereby accurately adjusting the damping force of the piston portion 30. Furthermore, the rubber portion 220 according to the modified example does not prevent oil from flowing from the first chamber Y1 into the pressure adjustment chamber 100 during the compression stroke.

[0053] (Modifications of the Retaining Structure of the Second Collar 49, the Second Valve 45, the First Collar 48, and the Housing 50) In the shock absorber 2 shown in Figure 2 etc., the housing bolt 214 and nut 55 of the rod 20 generate an axial force (in other words, an axial force) on the second collar 49, the second valve 45, the first collar 48, and the housing 50, but the axial force may also be generated by plastically deforming the tip of the rod 20.

[0054] FIG. 10 is a diagram showing an example of a holding structure according to a modified example. As shown in FIG. 10 , instead of forming the housing bolt 214 on the protrusion 212 of the first-side mounting portion 21 of the rod 20, the second collar 49, the second valve 45, the first collar 48, and the housing 50 may be disposed outside the protrusion 212, and then the protrusion 212 may be plastically deformed to expand the outer diameter of the first-side end of the protrusion 212. Even with this structure in which the first-side end of the rod 20 is plastically deformed to crimp the second collar 49, the second valve 45, the first collar 48, and the housing 50, the second collar 49, the second valve 45, the first collar 48, and the housing 50 are held with high reliability. In other words, even if the second collar 49, the second valve 45, the first collar 48, and the housing 50 are held by the crimped portion 215 formed by plastically deforming the rod 20, the housing 50 and the like are held with high reliability. Furthermore, the cost of the damping force changer 40 is reduced.

[0055] Note that Figure 10 illustrates an example of a configuration in which the second collar 49, the second valve 45, the first collar 48, and the housing 50 are crimped together by the crimping portion 215, but it is also possible to hold the second collar 49, the second valve 45, and the first collar 48 with nuts, and hold only the housing 50 by the crimping portion 215, for example.

[0056] (Modification of the seal of the pressure adjustment chamber 100) FIG. 11 is a diagram showing an example of a modified seal of the pressure adjusting chamber 100. In FIG. 11 , a rubber O-ring 57 may be provided on the outside of the second collar 49 between the first-side end face of the main body 211 of the first-side mounting portion 21 of the rod 20 and the second valve 45. By providing the O-ring 57, oil is prevented from flowing between the pressure adjustment chamber 100 and the first chamber Y1 through a gap between the outer circumferential surface of the protruding portion 212 of the rod 20 and, for example, the inside of the second valve 45, thereby improving the sealing performance of the pressure adjustment chamber 100.

[0057] (Modification of the second valve 45) FIG. 12 is a diagram showing an example of a second valve 245 according to a modified example. As shown in FIG. 12, the second valve 245 according to the modified example has a metal valve 230 corresponding to the second valve 45, a rubber valve 235 formed into a ring shape from a thin rubber plate, and a spring 237 that applies a force to the metal valve 230 and the rubber valve 235 in the direction of the first side.

[0058] The metal valve 230 differs from the second valve 45 in that it has multiple axial through holes 231 formed in the circumferential direction in the radial center (for example, at positions corresponding to the through holes 521 in the annular portion 52 of the housing 50). The rubber valve 235 is disposed on the second side of the metal valve 230 and is laminated on the metal valve 230. The rubber valve 235 may be integrated with the metal valve 230. 12, the spring 237 can be exemplified as a leaf spring whose inner periphery is sandwiched between the main body 211 of the first side mounting portion 21 of the rod 20 and the second collar 49. Alternatively, the spring 237 can be exemplified as a coil spring arranged, for example, between the main body 211 of the first side mounting portion 21 of the rod 20 or the nut 44 and the rubber valve 235.

[0059] The second valve 245 according to the modified example can prevent dust from entering the pressure adjustment chamber 100 from the first chamber Y1 through the through-hole 521 of the annular portion 52 of the housing 50. Since the rubber valve 235 is laminated on the metal valve 230, the metal valve 230 may be made thinner than the second valve 45 to reduce its rigidity.

[0060] Second Embodiment FIG. 13 is a diagram showing an example of a cross section of a shock absorber 202 according to the second embodiment. The shock absorber 202 according to the second embodiment differs from the shock absorber 2 according to the first embodiment in that it has a housing 250 that corresponds to the housing 50. The following describes the differences from the first embodiment. The same components in the first and second embodiments are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

[0061] The housing 250 differs from the housing 50 in that a cylindrical portion 251 corresponds to the cylindrical portion 51 . The cylindrical portion 251 has a cylindrical first portion 253 provided on the first side and a cylindrical second portion 254 provided on the second side. The outer diameter of the first portion 253 is larger than the outer diameter of the second portion 254. In the cylindrical portion 251, rubber is baked onto the inner circumferential surfaces of the first portion 253 and the second portion 254 and onto the outer circumferential surface of the second portion 254. A portion of the rubber baked onto the outer circumferential surface of the second portion 254 protrudes so that a cross-section of the second portion 254 along a plane parallel to the axial direction forms an arc, forming a seal portion 511 that provides a seal with the inner circumferential surface of the spool 46. On the other hand, no rubber is baked onto the outer circumferential surface of the first portion 253. The outer diameter of the first portion 253 is slightly smaller than the inner diameter of the cylindrical portion 461 of the spool 46, and the first portion 253 guides the axial movement of the spool 46. In other words, the housing 250 has the first portion 253 as an example of a support portion that supports the sliding movement of the spool 46. The housing 250 has the first portion 253, which allows the spool 46 to move smoothly in the axial direction.

[0062] FIG. 14 is a diagram showing an example of a housing 260 according to a modification of the housing 250 according to the second embodiment. The housing 260 of the modified example differs from the housing 250 in that the portion that guides the axial movement of the spool 46 is located on the second side of the sealing portion 511 that seals the gap with the inner surface of the spool 46. More specifically, the housing 260 according to the modification differs from the housing 50 according to the first embodiment in that a cylindrical portion 261 corresponding to the cylindrical portion 51 is provided. The cylindrical portion 261 has a cylindrical first portion 263 provided on the first side and a cylindrical second portion 264 provided on the second side. The outer diameter of the second portion 264 is larger than the outer diameter of the first portion 263. In the cylindrical portion 261, rubber is baked onto the outer peripheral surface of the first portion 263. A portion of the rubber baked onto the outer peripheral surface of the first portion 263 protrudes so that a cross-section of the rubber along a plane parallel to the axial direction forms an arc, forming a seal portion 511 that seals the gap with the inner peripheral surface of the spool 46. On the other hand, no rubber is baked onto the outer peripheral surface of the second portion 264. The outer diameter of the second portion 264 is slightly smaller than the inner diameter of the cylindrical portion 461 of the spool 46, and the second portion 264 guides the axial movement of the spool 46. In other words, the housing 260 has the second portion 264 as an example of a support portion that supports the sliding of the spool 46. The housing 260 has the second portion 264, which allows the spool 46 to move smoothly in the axial direction.

[0063] <Third embodiment> FIG. 15 is a diagram showing an example of a cross section of a shock absorber 302 according to the third embodiment. A shock absorber 302 according to the third embodiment differs from the shock absorber 2 according to the first embodiment in that it has a housing 350 corresponding to the housing 50 and a spool 360 corresponding to the spool 46. The following describes the differences from the first embodiment. The same components in the first and third embodiments are designated by the same reference numerals, and detailed descriptions thereof will be omitted.

[0064] Housing 350 differs from housing 50 in that cylindrical portion 351 corresponds to cylindrical portion 51. Cylindrical portion 351 differs from cylindrical portion 51 in that rubber is baked only on the inner circumferential surface from the axial center to the first side. A portion of the rubber baked on the inner circumferential surface of cylindrical portion 351 protrudes around the entire circumference so that a cross-section of the cross-section along a plane parallel to the axial direction forms an arc, forming seal portion 390 that seals between cylindrical portion 351 and spool 360.

[0065] Spool 360 differs from spool 46 in that cylindrical portion 361 corresponds to cylindrical portion 461. Cylindrical portion 361 differs from cylindrical portion 461 in that cylindrical portion 361 has inner portion 370 whose inner portion protrudes further toward the first side than the outer portion. The inner portion 370 is cylindrical, and the diameter of a first outer surface 371, which is the portion of the outer surface of the inner portion 370 on the first side from the axial center, is smaller than the diameter of a second outer surface 372, which is the portion of the outer surface of the inner portion 370 on the second side from the axial center. The diameter of second outer peripheral surface 372 is slightly smaller than the inner diameter of cylindrical portion 351 of housing 350, and cylindrical portion 351 of housing 350 guides the axial movement of spool 360. Since spool 360 has second outer peripheral surface 372, the axial movement of spool 360 becomes smooth. The diameter of the first outer peripheral surface 371 is larger than the inner diameter of the seal portion 390 , and the gap between the first outer peripheral surface 371 and the cylindrical portion 351 of the housing 350 is sealed by the seal portion 390 .

[0066] In the shock absorber 302 configured as described above, the cylindrical portion 351 of the housing 350 is disposed outside the cylindrical portion 361 of the spool 360, and therefore the inner diameter of the cylindrical portion 351 may be larger than the inner diameter of the cylindrical portion 51 of the housing 50 according to the first embodiment. As a result, the pressure adjustment chamber 100 can be made larger.

[0067] <Fourth embodiment> FIG. 16 is a diagram showing an example of a cross section of a shock absorber 402 according to the fourth embodiment. A shock absorber 402 according to the fourth embodiment differs from shock absorber 302 according to the third embodiment in that it has a housing 450 equivalent to housing 350 and a spool 460 equivalent to spool 360. The differences from the third embodiment will be described below. The same components in the third and fourth embodiments are designated by the same reference numerals, and detailed description thereof will be omitted.

[0068] Housing 450 differs from housing 350 in that it has a second cylindrical portion 452 that protrudes outward and toward the second side from the second end of cylindrical portion 351. Housing 450 also differs from housing 350 in that rubber is baked onto the entire inner circumferential surface of cylindrical portion 351.

[0069] Spool 460 differs from spool 360 in that inner portion 470, which corresponds to inner portion 370, has one outer peripheral surface 471. Outer peripheral surface 471 corresponds to first outer peripheral surface 371 according to the third embodiment, and a seal is formed between outer peripheral surface 471 and cylindrical portion 351 of housing 450 by seal portion 390. The diameter of the outer peripheral surface of cylindrical portion 361 of spool 460 is slightly smaller than the inner diameter of second cylindrical portion 452 of housing 450, and second cylindrical portion 452 of housing 450 guides the axial movement of spool 460. Housing 450 has second cylindrical portion 452, which allows spool 460 to move smoothly in the axial direction.

[0070] In the shock absorber 402 configured as described above, the second cylindrical portion 452 of the housing 450 is disposed outside the cylindrical portion 361 of the spool 460, and therefore the inner diameter of the cylindrical portion 351 of the housing 450 may be larger than the inner diameter of the cylindrical portion 51 of the housing 50 according to the first embodiment. As a result, the pressure adjustment chamber 100 can be made larger. [Explanation of symbols]

[0071] 1...Suspension device, 2, 202, 302, 402...Shock absorber, 3...Coil spring, 10...Cylinder portion, 20...Rod, 30...Piston portion, 31...Piston, 40...Damping force change portion, 41...First valve, 45, 245...Second valve, 46...Spool (an example of a sliding member), 50...Housing, 51...Cylindrical portion, 52...Annular portion (an example of a restricting portion, a main body), 100...Pressure adjustment chamber (an example of a back pressure chamber), 215...Crimped portion, 253...First portion (an example of a supporting portion), 264...Second portion (an example of a supporting portion), 511...Seal portion (an example of a sliding seal portion), 522...Rubber portion (an example of a seating portion), Y1...First chamber, Y2...Second chamber

Claims

1. a first valve disposed in a first communication passage that communicates a first chamber and a second chamber defined by a piston held by a rod, the first valve opening the first communication passage when a second pressure, which is a pressure in the second chamber, is higher than a first pressure, which is a pressure in the first chamber, and closing the first communication passage when the first pressure is higher than the second pressure; a second valve provided in a second communication passage formed around the rod and communicating between the first chamber and the second chamber, the second valve elastically deforming to close the second communication passage when the second pressure is higher than the first pressure and to increase the volume of a back pressure chamber that generates back pressure against the first valve, and opening the second communication passage when the first pressure is higher than the second pressure; a housing that accommodates the second valve and defines the back pressure chamber together with the second valve, the housing having a restricting portion that restricts the elastic deformation of the second valve, and a seating portion that is a portion on which the second valve is seated and provides a seal between the housing and the second valve; A shock absorber comprising:

2. a sliding member that defines the back pressure chamber and is slidably fitted into the housing, The housing has a sliding seal portion that seals between the housing and the sliding member. The shock absorber according to claim 1 .

3. The housing has a support portion that supports the sliding of the sliding member. The shock absorber according to claim 2 .

4. The housing has a main body formed of metal and rubber that is baked onto the main body to form the seating portion. The shock absorber according to claim 1 .

5. The housing is held by a crimped portion formed by plastically deforming the rod. The shock absorber according to claim 1 .

6. The housing and the second valve are held by a crimped portion to which the rod is crimped. The shock absorber according to claim 1 .

7. A shock absorber according to any one of claims 1 to 6; a coil spring disposed around the shock absorber; A suspension device comprising:

Images