Buffer device

Abstract

This invention provides a technology that can apply a desired set load to a valve. [Solution] A shock absorber comprising: a piston that is movably fitted inside a cylinder filled with working fluid and divides the inside of the cylinder into two chambers; a rod whose one end is connected to the piston and whose other end is exposed to the outside of the cylinder; a flow path through which working fluid flows from one chamber to the other as the piston moves; and a damping force generating unit provided in the flow path to generate a damping force, wherein the damping force generating unit has a passage forming member in which a passage constituting part of the flow path is formed; a first generating unit supported by the passage forming member and generating a damping force by reducing the opening area of ​​the passage; and a second generating unit supported by the passage forming member and positioned downstream of the first generating unit, wherein the passage forming member has a first support unit that supports the first generating unit and a second support unit that supports the second generating unit at a different location from the first support unit.

Description

Technical Field

[0001] The present invention relates to a buffer device.

Background Art

[0002] For example, in the hydraulic shock absorber described in Patent Document 1, a piston rod is movably inserted into a cylinder via a piston. The piston partitions the cylinder into a rod-side oil chamber and a rodless-side oil chamber. The piston forms an extension-side main port and a compression-side main port that communicate the two oil chambers. An extension-side damping valve composed of a leaf valve is provided at the outlet end of the extension-side main port so as to be openable and closable. A compression-side damping valve composed of a leaf valve is provided at the outlet end of the compression-side main port so as to be openable and closable. The hydraulic shock absorber described in Patent Document 1 is provided with a compression-side bypass port that communicates the two oil chambers with each other in parallel with the compression-side main port, and a compression-side sub-valve is provided at the outlet end of the compression-side bypass port so as to be openable and closable. A valve retainer, a compression-side damping valve formed by stacking a plurality of leaf valves having different outer diameters, a small-diameter spacer, a compression-side sub-valve formed by stacking one or more leaf valves, a piston, an extension-side damping valve formed by stacking a plurality of leaf valves having different outer diameters, and a valve retainer are sequentially inserted in series and clamped by nuts screwed onto the ends.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the hydraulic shock absorber described in Patent Document 1, the compression-side damping valve and the compression-side sub-valve are laminated on the piston rod and fixed with one nut. Since the thickness of the valves varies, it becomes difficult to apply a desired set load to the valves as the number of valve laminations increases. The present invention aims to provide a shock absorber capable of applying a desired set load to a valve. [Means for solving the problem]

[0005] The present invention, completed with this objective in mind, is a shock absorber comprising: a cylinder portion in which a working fluid is sealed; a piston movably fitted inside the cylinder portion and dividing the inside of the cylinder portion into two chambers; a rod with one end connected to the piston and the other end exposed to the outside of the cylinder portion; a flow path through which the working fluid flows from one of the two chambers to the other chamber as the piston moves; and a damping force generating portion provided in the flow path and generating a damping force, wherein the damping force generating portion comprises: a passage forming member in which a passage constituting a part of the flow path is formed; a first generating portion supported by the passage forming member and generating a damping force by reducing the opening area of ​​the passage; and a second generating portion supported by the passage forming member and positioned downstream of the first generating portion, wherein the passage forming member comprises: a first support portion supporting the first generating portion; and a second support portion supporting the second generating portion at a different location from the first support portion. [Effects of the Invention]

[0006] According to the present invention, a shock absorber can be provided that can apply a desired set load to a valve. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows an example of a schematic configuration of a suspension system according to the first embodiment. [Figure 2] This figure shows an example of a cross-section of the piston section. [Figure 3] This is an example of a perspective view of the components that make up the piston. [Figure 4] This diagram illustrates the operation of the piston during the extension stroke at very low speed. [Figure 5] This diagram illustrates the operation of the piston during high-speed extension strokes. [Figure 6] This figure shows an example of a cross-section of the piston portion according to the second embodiment. [Figure 7] This figure shows an example of a cross-section of the piston portion according to the third embodiment. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described in detail below with reference to the attached drawings. <First Embodiment> Figure 1 is a diagram showing an example of a schematic configuration of the suspension device 1 according to the first embodiment. The suspension system 1 is a strut-type suspension used in four-wheeled vehicles such as passenger cars, and as shown in Figure 1, it comprises a hydraulic shock absorber 2 and a coil spring 3 positioned outside the shock absorber 2. The suspension system 1 also includes a lower spring seat 4 that supports the first axial end (lower side in Figure 1) of the rod 20, which will be described later, in the coil spring 3. The suspension system 1 also includes an upper spring seat 5 that supports the second axial end (upper side in Figure 1) of the rod 20 in the coil spring 3.

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

[0010] In the following, 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 centerline of the cylindrical cylinder 11, which will be described later. In the axial direction, the first side (lower side in Figure 1) and the second side (upper side in Figure 1) may be simply referred to as the "first side" and the "second side," respectively. Also, the direction intersecting the axial direction (for example, the orthogonal direction) may be referred to as the "radial direction." In the radial direction, the side of the cylinder 11 that is on the centerline may be simply referred to as the "inside," and the side that is away from the centerline may be simply referred to as the "outside."

[0011] The shock absorber 2 comprises a cylinder portion 10 that contains oil as an example of a working fluid, and a rod 20 whose second end protrudes from the cylinder portion 10 and whose first end is movably inserted into the cylinder portion 10. The shock absorber 2 also comprises a piston portion 30 provided at the first end of the rod 20 and a bottom portion 90 provided at the first end of the cylinder portion 10.

[0012] The cylinder section 10 includes a cylinder 11 for containing oil and an outer cylinder 12 provided outside the cylinder 11. The cylinder section 10 also includes a rod guide section 14 for movably supporting the rod 20 and a bump stopper cap 15 attached to the second end of the outer cylinder 12. The cylinder section 10 also includes an oil seal 16 to prevent oil leakage from the cylinder section 10 and the entry of foreign matter into the cylinder section 10.

[0013] Figure 2 shows an example of a cross-section of the piston portion 30. In Figure 2, the portion to the right of the center line is an example of a cross-section of the area where the compression passage 42, which will be described later, is formed, and the portion to the left of the center line is an example of a cross-section of the area where the extension passage 43, which will be described later, is formed. Figure 3 is an example of a perspective view of the components that make up the piston section 30.

[0014] The piston portion 30 moves axially as the rod 20 moves. The piston portion 30 includes a piston 40 in which a plurality of passages through which oil passes are formed, and a pressure-side valve group 60 provided on the second side of the piston 40. The piston portion 30 also includes an extension-side upstream valve group 70 provided on the first side of the piston 40, and an extension-side downstream valve group 80 disposed on the downstream side of the extension-side upstream valve group 70. The piston portion 30 also includes an annular annular member 31 and a valve stopper 32 disposed on the second side of the pressure-side valve group 60. The piston portion 30 also includes an annular annular member 33 and a valve stopper 34 disposed on the first side of the extension-side upstream valve group 70, and a nut 35. The piston portion 30 also includes an annular annular member 36 and a valve stopper 37 disposed on the first side of the extension-side downstream valve group 80, and a nut 38. The piston 40, the pressure-side valve group 60, the extension-side downstream valve group 80, the annular member 31, the valve stopper 32, the annular member 36, and the valve stopper 37 are fixed by tightening the nut 38 to a male thread 20e formed on the rod 20. The extension-side upstream valve group 70, the annular member 33, and the valve stopper 34 are fixed by tightening the nut 35 to a male thread 47e (described later) formed on the piston 40.

[0015] (Piston 40) The piston 40 divides the space inside the cylinder 11 (see FIG. 1) into a first oil chamber Y1 (see FIG. 1), which is the space on the first side in the axial direction, and a second oil chamber Y2 (see FIG. 1), which is the space on the second side in the axial direction.

[0016] The piston 40 has a through hole 41 provided inside, a pressure-side passage 42 provided outside the through hole 41, and an extension-side passage 43 provided outside the through hole 41. The piston 40 also has a second inner protrusion 44 provided at a portion inside the second side of the pressure-side passage 42, and a second outer protrusion 45 provided outside the second inner protrusion 44 on the second side of the pressure-side passage 42.

[0017] Further, the piston 40 has a first surface 46 which is a surface orthogonal to the axial direction and in which an opening on the first side in the extension-side passage 43 is formed. Further, the piston 40 has a first inner protruding portion 47 which protrudes cylindrically from the first surface 46 to the first side at a portion inside the first surface 46. Further, the piston 40 has a first outer protruding portion 48 which protrudes cylindrically from the first surface 46 to the first side at a portion outside the first surface 46. Further, in the piston 40, a recess 49 which is recessed from the first surface 46 to the second side over the entire circumference is formed inside the first outer protruding portion 48.

[0018] The through-hole 41 is a cylindrical hole. And the first-side end portion 21 of the rod 20 is passed through the through-hole 41. Thereby, the piston 40 is attached to the first-side end portion 21 of the rod 20. And the center-line direction of the through-hole 41 becomes the axial direction of the rod 20. The pressure-side passage 42 is a passage that enables the flow of oil between the first oil chamber Y1 and the second oil chamber Y2 during the compression stroke of the buffer device 2. And the pressure-side passage 42 is provided at a plurality of locations (for example, six locations) at substantially equal intervals in the circumferential direction.

[0019] The extension-side passage 43 is a passage that enables the flow of oil between the second oil chamber Y2 and the first oil chamber Y1 during the extension stroke of the buffer device 2. And the extension-side passage 43 is provided at a plurality of locations (for example, six locations) at substantially equal intervals in the circumferential direction. The extension-side passage 43 is formed at a location different from the location where the pressure-side passage 42 is provided in the circumferential direction.

[0020] The second inner protruding portion 44 is formed in a substantially annular shape. The second inner protruding portion 44 is provided around the through-hole 41. And the second inner protruding portion 44 protrudes axially toward the second side from the opening on the second side of the pressure-side passage 42. The second inner protruding portion 44 contacts an inner portion of the pressure-side valve group 60.

[0021] The second outer projection 45 is formed in an annular shape. The second outer projection 45 is located second to the compression passage 42, and is provided outside the second opening in the compression passage 42. The second outer projection 45 also protrudes axially towards the second side of the second opening in the compression passage 42. The projection height of the second outer projection 45 is slightly (for example, 0.05 mm) higher than the projection height of the second inner projection 44.

[0022] The first inner projection 47 is formed in a cylindrical shape around the through hole 41. A male thread 47e is formed at the first end of the first inner projection 47. A nut 35 is tightened onto the male thread 47e. The first outer projection 48 is formed in a cylindrical shape. The first outer projection 48 is formed on the first side of the extension passage 43, outside the first side opening of the extension passage 43. The projection height of the first outer projection 48 from the first surface 46 is slightly (e.g., 0.05 mm) higher than that of the first inner projection 47. Due to the shape described above, the piston 40 has a housing space 55 for housing the extension-side upstream valve group 70, surrounded by the outer circumferential surface of the first inner projection 47, the inner circumferential surface of the first outer projection 48, the first surface 46, and the recess 49.

[0023] The piston 40 can be exemplified by forming it by filling a mold having a predetermined shape with metal powder and sintering the filled metal powder. Alternatively, the piston 40 can be exemplified by forming a single part by connecting two sintered products that are divided in the axial direction. The through hole 41, compression passage 42, and extension passage 43 may be formed by molding, or they may be formed by machining the sintered product, for example.

[0024] (Compression valve group 60) The compression valve group 60 is constructed by stacking multiple (five in Figure 2) annular plates made of metal. More specifically, the compression valve group 60 includes a first valve 61 that seats on the second outer projection 45 of the piston 40, a second valve 62 positioned adjacent to the first valve 61, and a third valve 63 positioned adjacent to the second valve 62. The compression valve group 60 also includes a fourth valve 64 positioned adjacent to the third valve 63, and a fifth valve 65 positioned adjacent to the fourth valve 64. The first valve 61, second valve 62, third valve 63, fourth valve 64, and fifth valve 65 have through holes 68 formed inside for the rod 20 to pass through, and are arranged sequentially around the rod 20 from the piston 40 toward the second side. The diameter of the through-hole 68 is smaller than the inner diameter of the second inner projection 44, and the inner portion of each of the five valves is fixed between the second inner projection 44 and the annular member 31.

[0025] The outer diameters of the first valve 61, the second valve 62, and the third valve 63 are the same, and the outer diameter of the fourth valve 64 is smaller than the outer diameter of the first valve 61. For example, the outer diameter of the fourth valve 64 can be exemplified as being 2 / 3 of the outer diameter of the first valve 61. The outer diameter of the fifth valve 65 is smaller than the outer diameter of the fourth valve 64. For example, the outer diameter of the fifth valve 65 can be exemplified as being 1 / 2 of the outer diameter of the fourth valve 64.

[0026] (Extension-side upstream valve group 70) The extension-side upstream valve group 70 is constructed by stacking multiple (two in Figure 2) annular plates made of metal. More specifically, the extension-side upstream valve group 70 has a first valve 71 seated on the first surface 46 of the piston 40 in a portion outside the extension-side passage 43 and inside the recess 49, and a second valve 72 positioned adjacent to the first valve 71. The first valve 71 and the second valve 72 have through holes 78 formed on their insides through which the rod 20 passes, and are arranged around the rod 20 in order from the extension-side passage 43 toward the first side. The diameter of the through holes 78 is larger than the outer diameter of the first inner projection 47, and the first valve 71 and the second valve 72 are fixed between the portion on the first surface 46 inside the extension-side passage 43 and the annular member 33. The number of valves constituting the extension-side upstream valve group 70 is not particularly limited.

[0027] The outer diameters of the first valve 71 and the second valve 72 are larger than the inner diameter of the recess 49 of the piston 40, and cover the first side of the extension passage 43 formed in the piston 40. The first valve 71 and the second valve 72 are supported by the piston 40 at their inner portions (in other words, their inner circumferences), with their outer portions (in other words, their outer circumferences) being free ends, and they flex starting from the outermost circumference of the annular member 33. The portion of the first surface 46 of the piston 40 that is inside the extension passage 43 becomes the first support portion 51 that supports the first valve 71 and the second valve 72. The portion of the first surface 46 of the piston 40 that is outside the extension passage 43 but inside the recess 49 becomes the first seat portion 52 on which the first valve 71 sits. Hereinafter, the portion of the first surface 46 of the piston 40 that is inside the extension passage 43 may be referred to as the first support portion 51, and the portion of the first surface 46 that is outside the extension passage 43 but inside the recess 49 may be referred to as the first seat portion 52.

[0028] The first valve 71 has multiple (for example, three) slits 711 formed in the circumferential direction, which are linearly cut out from the outer edge inward. The inner position of the slits 711 is located inside the first seating portion 52 and outside the first support portion 51. Therefore, even when the first valve 71 is seated on the first seating portion 52, oil flows through the slits 711.

[0029] The extension-side upstream valve group 70, the annular member 33, and the valve stopper 34 are fixed by tightening a nut 35 onto a male thread 47e formed on the piston 40. The extension-side upstream valve group 70, the annular member 33, the valve stopper 34, and the nut 35 are then arranged within the housing space 55. In other words, a gap is formed between the first side surface of the nut 35 and the second side surface of the first valve 81 of the extension-side downstream valve group 80.

[0030] (Extension-side downstream valve group 80) The extension-side downstream valve group 80 is constructed by stacking multiple (five in Figure 2) annular plates made of metal. More specifically, the extension-side downstream valve group 80 has a first valve 81 that sits on the first outer projection 48 of the piston 40, a second valve 82 positioned adjacent to the first valve 81, and a third valve 83 positioned adjacent to the second valve 82. The extension-side downstream valve group 80 also has a fourth valve 84 positioned adjacent to the third valve 83, and a fifth valve 85 positioned adjacent to the fourth valve 84. The first valve 81, second valve 82, third valve 83, fourth valve 84, and fifth valve 85 have through holes 88 formed inside for the rod 20 to pass through, and are arranged around the rod 20 in order from the extension-side passage 43 toward the first side. The diameter of the through-hole 88 is smaller than the inner diameter of the first inner projection 47, and the inner portions of the five valves are fixed between the first inner projection 47 and the annular member 36.

[0031] The outer diameter of the first valve 81 is larger than the outer diameter of the first outer projection 48 of the piston 40, and covers the first side of the housing space 55 formed in the piston 40. The outer diameters of the second valve 82, third valve 83, fourth valve 84, and fifth valve 85 are equal to the outer diameter of the first valve 81. The first valve 81, second valve 82, third valve 83, fourth valve 84, and fifth valve 85 are supported at their inner portions (in other words, their inner circumferences), with their outer portions (in other words, their outer circumferences) being free ends, and they flex starting from the outermost circumference of the annular member 36. The first end face of the first inner projection 47 of the piston 40 becomes a second support portion 53 that supports the first valve 81, second valve 82, third valve 83, fourth valve 84, and fifth valve 85. The first outer projection 48 of the piston 40 becomes a second seating portion 54 on which the first valve 81 sits.

[0032] The first valve 81 has multiple (for example, six) slits 811 formed in the circumferential direction, which are linearly cut out from the outer edge inward. The inner position of the slits 811 is located inside the second seating portion 54 and outside the second support portion 53. Therefore, even when the first valve 81 is seated on the second seating portion 54, oil flows through the slits 811.

[0033] Furthermore, since the projection height of the first outer projection 48 from the first surface 46 is slightly higher than that of the first inner projection 47, the extension-side downstream valve group 80 is assembled to the piston 40 in a bent state such that the outer portion is located on the first side than the inner portion. This applies a set load to the extension-side downstream valve group 80. The number of plates constituting the extension-side downstream valve group 80 is not particularly limited.

[0034] Next, the operation of the piston section 30 will be described. Figure 4 is a diagram illustrating the operation of the piston section 30 during a very low-speed extension stroke. Figure 5 is a diagram illustrating the operation of the piston section 30 during a high-speed extension stroke. During the extension stroke, the rod 20 moves axially to the second side relative to the cylinder portion 10. The piston 40, which is fixed to the rod 20, compresses the oil in the second oil chamber Y2, increasing the pressure in the second oil chamber Y2.

[0035] In this case, when the movement speed of the rod 20 is small, so-called very low speed, the oil in the second oil chamber Y2 opens the extension-side upstream valve group 70 that closes the extension-side passage 43, as shown in Figure 4 (arrows shown by solid lines in the figure). On the other hand, in the case of very low speed, the pressure in the second oil chamber Y2 does not become large enough to open the extension-side downstream valve group 80. Therefore, the oil flows into the first oil chamber Y1 through the slit 811 of the first valve 81 of the extension-side downstream valve group 80. Hereinafter, the passage through which the oil flows from the second oil chamber Y2 through the extension-side passage 43 of the piston 40 to the first oil chamber Y1 may be referred to as the extension-side passage 91.

[0036] Furthermore, in the case of extremely low speeds, where the movement speed of the rod 20 is very small, the pressure in the second oil chamber Y2 does not become large enough to open the extension-side upstream valve group 70. In the case of extremely low speeds, the oil flows into the first oil chamber Y1 through the extension-side passage 43, the slit 711 of the first valve 71 of the extension-side upstream valve group 70, and the slit 811 of the first valve 81 of the extension-side downstream valve group 80.

[0037] In the case of high speed, where the rod 20 moves at a large speed, the oil in the second oil chamber Y2 opens the extension-side upstream valve group 70 that closes the extension-side passage 43 and the extension-side downstream valve group 80 that closes the housing space 55, as shown in Figure 5, and flows into the first oil chamber Y1. The piston section 30 generates a damping force due to the resistance created when oil flows through the extension passage 43, the extension upstream valve group 70, and the extension downstream valve group 80.

[0038] As described above, the shock absorber 2 comprises a cylinder portion 10 in which oil is sealed, and a piston 40 that is movably fitted inside the cylinder portion 10 and divides the inside of the cylinder portion 10 into two chambers (for example, a first oil chamber Y1 and a second oil chamber Y2). The shock absorber 2 also comprises a rod 20, one end (for example, the first side) of which is connected to the piston 40 and the other end (for example, the second side) is exposed to the outside of the cylinder portion 10. The shock absorber 2 also comprises an extension-side passage 91 (an example of a passage) through which oil flows from the second oil chamber Y2 (an example of one chamber) to the first oil chamber Y1 (an example of the other chamber) as the piston 40 moves. The shock absorber 2 also comprises a piston portion 30 (an example of a damping force generating portion) provided in the extension-side passage 91 to generate damping force. The piston section 30 has a piston 40 (an example of a passage forming member) in which an extension passage 43 (an example of a passage) is formed, which separates the first oil chamber Y1 and the second oil chamber Y2 and constitutes a part of the extension passage 91. The piston section 30 also has an extension upstream valve group 70 (an example of a first generating part) that is supported by the piston 40 and generates damping force by reducing the opening area of ​​the extension passage 43. The piston section 30 also has an extension downstream valve group 80 (an example of a second generating part) that is supported by the piston 40 and is located downstream of the extension upstream valve group 70. The piston 40 has a first support part 51 that supports the extension upstream valve group 70 and a second support part 53 that supports the extension downstream valve group 80 at a different location from the first support part 51.

[0039] In the piston section 30 described above, the piston 40 supports the extension-side downstream valve group 80 at a second support section 53 that is different from the first support section 51 that supports the extension-side upstream valve group 70, so that the desired set load can be applied to the extension-side downstream valve group 80 with high precision. That is, for example, in a configuration in which the extension-side upstream valve group 70 and the extension-side downstream valve group 80 are stacked (hereinafter sometimes referred to as the "comparative configuration"), the number of stacked valves increases. When the number of stacked valves increases, the overall thickness of the stacked valves varies due to variations in the thickness of each valve, making it difficult to apply the desired set load to the stacked valves. With the piston section 30 described above, the number of stacked valves can be reduced compared to the comparative configuration, so that the desired set load can be applied with high precision. In other words, since the set load variation is reduced by the damping device 2, the variation in damping force generation is also reduced.

[0040] Here, the extension-side upstream valve group 70 has an annular first valve 71 (an example of an upstream valve) with the first support portion 51 side as the fixed end, and the extension-side downstream valve group 80 has an annular first valve 81 (an example of a downstream valve) with the second support portion 53 side as the fixed end. The piston 40 further has a first seating portion 52 on which the first valve 71 is seated, and a second seating portion 54 on which the first valve 81 is seated at a different location from the first seating portion 52. The distance from the axis of the rod 20 at the first seating portion 52 is smaller than the distance from the axis at the second seating portion 54. This makes it possible to position the extension-side downstream valve group 80 downstream of the extension-side upstream valve group 70. In addition, the fixed end of the first valve 81 of the extension-side downstream valve group 80 is in contact with the second support portion 53 of the piston 40, and the free end is in contact with the second seating portion 54 of the piston 40. Therefore, the set load generated in the extension-side downstream valve group 80 depends on the positions of the second support portion 53 and the second seating portion 54 of the piston 40, so the variation in set load is smaller compared to, for example, a configuration in which the first valve 81 is stacked on the extension-side upstream valve group 70. Note that the distance from the axis of the rod 20 at the first support portion 51 is greater than the distance from the axis at the second support portion 53.

[0041] The second support portion 53 is the axial end face of the rod 20 in the first inner projection 47 (an example of an inner cylindrical portion) through which the rod 20 passes, and the extension-side upstream valve group 70 is positioned in the axial direction between the first surface 46 constituting the first support portion 51 and the axial end face of the first inner projection 47 (in other words, the second support portion 53). This makes it possible to position the extension-side downstream valve group 80 downstream of the extension-side upstream valve group 70.

[0042] The second support portion 53 is the end face of the first inner projection 47 through which the rod 20 passes, and a male thread 47e is formed on the outer circumferential surface of the first inner projection 47, to which a nut 35 (an example of a first nut) that fixes the extension-side upstream valve group 70 to the piston 40 is tightened. In addition, a male thread 20e is formed on the rod 20, to which a nut 38 (an example of a second nut) that fixes the extension-side downstream valve group 80 to the piston 40 is tightened. With the piston portion 30, the axial force acting on the extension-side upstream valve group 70 and the axial force acting on the extension-side downstream valve group 80 can be applied at different locations, so that the set loads of the extension-side upstream valve group 70 and the extension-side downstream valve group 80 can be set to the desired value with high precision.

[0043] The second support portion 53 is the first axial end face of the rod 20 at the first inner projection 47 through which the rod 20 passes, and the second seating portion 54 is the second axial end face of the rod 20 at the first outer projection 48 (an example of an outer cylindrical portion) formed on the outer circumference of the piston 40. The axial position of the second end face is located closer to the first oil chamber Y1 than the axial position of the first end face. As a result, the set load acts with high accuracy on the extension-side downstream valve group 80.

[0044] Furthermore, in the piston section 30, the extension-side upstream valve group 70, the annular member 33, and the valve stopper 34 can be fixed to the piston 40 with nuts 35 before assembling the compression-side valve group 60, the piston 40, the extension-side downstream valve group 80, etc., to the rod 20. Therefore, in the manufacturing process, the process of assembling the compression-side valve group 60, the piston 40, the extension-side downstream valve group 80, etc., to the rod 20 can be separated from the process of fixing the extension-side upstream valve group 70, the annular member 33, and the valve stopper 34 to the piston 40 with nuts 35. As a result, the time required for the process of assembling the piston section 30 to the rod 20 can be shortened.

[0045] In the above-described embodiment, the extension-side upstream valve group 70 and the extension-side downstream valve group 80, which generate damping force during the extension stroke, have different fixed ends, support parts to which the free ends contact, seating parts, and components that apply axial force (e.g., nuts). However, the invention is not limited to devices that generate damping force during the extension stroke, but may also be applied to devices that generate damping force during the compression stroke. For example, the compression-side valve group 60, which generates damping force during the compression stroke, may be divided into an upstream valve group and a downstream valve group, and the fixed ends, support parts to which the free ends contact, seating parts, and components that apply axial force may be different for each. Furthermore, a valve group provided inside a device located outside the cylinder section 10 and generating damping force outside the cylinder section 10 may be divided into an upstream valve group and a downstream valve group, and the fixed ends, support parts to which the free ends contact, seating parts, and components that apply axial force may be different for each. In other words, the damping force generating unit, which is provided in the oil flow path to generate damping force and to which the above-described configuration is applied, is not limited to the piston unit 30 provided inside the cylinder unit 10, but may also be provided outside the cylinder unit 10.

[0046] <Second Embodiment> Figure 6 shows an example of a cross-section of the piston portion 230 according to the second embodiment. The piston portion 230 according to the second embodiment differs from the piston portion 30 according to the first embodiment in its structure for applying axial force to the extension-side upstream valve group 70. The differences from the first embodiment will be described below. The same reference numerals are used for the same parts in the first and second embodiments, and their detailed descriptions will be omitted.

[0047] The piston portion 230 does not have the nut 35 that the piston portion 30 has. Also, the piston 240, which corresponds to the piston 40 according to the first embodiment and is included in the piston portion 230, does not have a male thread 47e formed thereon. Instead, a groove 247g recessed from the outer circumferential surface is formed at the first end of the first inner projection 47. A cylindrical ring 235, with a portion of its circumferential direction cut out, is fitted into the groove 247g. The ring 235 is, for example, a C-ring, and its outer diameter is larger than the diameter of the through-hole 78 of the first valve 71 and the second valve 72, and less than or equal to the outer diameter of the first support portion 51.

[0048] The piston portion 230 has an elastic member 236 between the ring 235 and the valve stopper 34. The elastic member 236 can be exemplified as a compression coil spring or rubber. If it is a compression coil spring, it may be a tapered spring in which the diameter on the ring 235 side is smaller than the diameter on the valve stopper 34 side. This makes it possible to reduce the outer diameter of the ring 235.

[0049] With the piston section 230, similar to the piston section 30, the set loads of the extension-side upstream valve group 70 and the extension-side downstream valve group 80 can be set to a desired value with high precision, and the time required for the process of assembling the piston section 230 onto the rod 20 can be shortened.

[0050] <Third Embodiment> Figure 7 shows an example of a cross-section of the piston portion 330 according to the third embodiment. The piston portion 330 according to the third embodiment differs from the piston portion 30 according to the first embodiment in its structure for applying axial force to the extension-side upstream valve group 70. The 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 their detailed descriptions will be omitted.

[0051] The piston portion 330 does not have the nut 35 that the piston portion 30 has. Also, the piston 340, which corresponds to the piston 40 in the first embodiment and is included in the piston portion 330, does not have a male thread 47e formed thereon. The piston portion 330 is cylindrical and has a fixing member 335 that is fixed to the piston 340 by joining the first inner projection 47 of the piston 340 to the inner portion on the first side. The outer diameter of the fixing member 335 is larger than the outer diameter of the annular member 33 and less than or equal to the outer diameter of the valve stopper 34. The piston portion 330 is joined to the piston 340 after the extension upstream valve group 70, the annular member 33 and the valve stopper 34 have been assembled to the piston 340. The method of joining the fixing member 335 to the piston 340 is not particularly limited. Examples of joining methods include welding such as laser welding, bonding, and crimping. In Figure 7, the joint area 350, where the fixing member 335 is joined to the piston 340 by laser welding, is colored black.

[0052] With the piston section 330, similar to the piston section 30, the set loads of the extension-side upstream valve group 70 and the extension-side downstream valve group 80 can be set to a desired value with high precision, and the time required for the process of assembling the piston section 330 onto the rod 20 can be shortened. [Explanation of Symbols]

[0053] 1...Suspension device, 2...Buffing device, 10...Cylinder section, 11...Cylinder, 20...Rod, 20e...Male screw, 30...Piston section (example of damping force generating section), 35...Nut (example of first nut), 38...Nut (example of second nut), 40, 240, 340...Piston (example of passage forming member), 47...First inner projection (example of inner cylindrical section), 47e...Male screw, 51...First support section, 52...First seating section, 53...Second support section, 54...Second seating section, 70...Extension side upstream valve group (example of first generating section), 71...First valve (example of upstream valve), 80...Extension side downstream valve group (example of second generating section), 81...First valve (example of downstream valve), 91...Extension side flow path (example of flow path), Y1...First oil chamber, Y2...Second oil chamber

Claims

1. A cylinder section into which the working fluid is sealed, A piston is movably fitted inside the cylinder portion and divides the inside of the cylinder portion into two chambers, A rod having one end connected to the piston and the other end exposed to the outside of the cylinder portion, The movement of the piston creates a flow path through which the working fluid flows from one of the two chambers to the other. A damping force generating unit is provided in the aforementioned flow path to generate a damping force, Equipped with, The damping force generating unit comprises a passage forming member having a passage that constitutes a part of the flow path, a first generating unit supported by the passage forming member and generating damping force by reducing the opening area of ​​the passage, and a second generating unit supported by the passage forming member and positioned downstream of the first generating unit. The passage forming member has a first support portion that supports the first generation portion, and a second support portion that supports the second generation portion at a location different from the first support portion. Buffer device.

2. The first generating unit has an annular upstream valve with the first support unit side as the fixed end, The second generating unit has an annular downstream valve with the second support unit side as the fixed end, The passage forming member further comprises a first seating portion on which the upstream valve is seated, and a second seating portion on which the downstream valve is seated at a different location from the first seating portion, wherein the distance from the axis of the rod at the first seating portion is smaller than the distance from the axis at the second seating portion. The shock absorber according to claim 1.

3. The second support portion is the axial end face of the rod in the inner cylindrical portion through which the rod passes, The first generating portion is positioned in the axial direction between the first support portion and the end face, The shock absorber according to claim 1.

4. The second support portion is the axial end face of the rod in the inner cylindrical portion through which the rod passes, A male thread is formed on the outer circumferential surface of the inner cylindrical portion, onto which a first nut is tightened to fix the first generating portion to the passage forming member. The rod has a male thread formed on it, which is used to fasten a second nut that secures the second generating portion to the passage forming member. The shock absorber according to claim 1.

5. The second support portion is the first axial end face of the rod in the inner cylindrical portion through which the rod passes, The second seating portion is the second axial end face of the rod in the outer cylindrical portion formed on the outer circumference of the passage forming member, The axial position on the second end face is located on the other side of the chamber than the axial position on the first end face. The shock absorber according to claim 2.

Images