Buffer device

Abstract

The present invention provides a buffer device that can prevent the valve from sticking to the piston. [Solution] A shock absorber comprising: a piston that partitions an oil chamber in a cylinder containing hydraulic fluid, has a through hole formed in the center through which a rod passes, and has an oil passage formed outside the through hole for passing hydraulic fluid; and an annular valve that is supported by the piston and has an outer circumference as a free end, wherein the piston has a base end that is provided so as to protrude to one side in the direction of the centerline from the opening of the oil passage around the through hole and contacts the inner circumference of the valve, and a seating portion that is provided so as to protrude to one side outside the oil passage and to one side from the opening and seats the outer circumference of the valve, the seating portion has a top that protrudes the most to one side from the opening, an inner surface that slopes inward from the top, and an outer surface that slopes outward from the top, and the valve contacts the top but does not contact the inner surface.

Description

Technical Field

[0004] , ,

[0005] , , , , , ,

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

Background Art

[0002] For example, the hydraulic shock absorber described in Patent Document 1 is configured as follows. That is, a piston valve assembled to the lower end of a piston rod and movably inserted into a cylinder partitions the inside of the cylinder into an upper chamber and a lower chamber. At the same time, a base valve is disposed at the lower end of the cylinder, and each valve has an opening window recessed and surrounded by a seat surface and a leaf valve opposed to the opening window. And the hydraulic shock absorber described in Patent Document 1 is characterized in that the height inside the seat surface near the opening window is lower than the height outside.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the shape of the opening window described in Patent Document 1, there is room for improvement in that abnormal noise occurs due to the valve sticking to the seat surface. In particular, at low temperatures where the viscosity of the oil increases, when transitioning from the extension stroke to the compression stroke, the adsorption force between the valve and the piston is high, and the valve is likely to stick to the seat surface. An object of the present invention is to provide a buffer device capable of suppressing the valve from sticking to the piston.

Means for Solving the Problems

[0005] <00The present invention, completed with this objective in mind, comprises a piston that partitions an oil chamber in a cylinder containing hydraulic fluid, has a through hole formed in its center for a rod to pass through, and has an oil passage formed outside the through hole for the hydraulic fluid to pass through, and an annular valve that is supported by the piston and has an outer circumference as a free end, wherein the piston has a base end that is provided so as to protrude to one side in the direction of the centerline from the opening of the oil passage around the through hole and contacts the inner circumference of the valve, and a seating portion that is provided so as to protrude to one side beyond the opening outside the oil passage and seats the outer circumference of the valve, the seating portion has a top that protrudes the most to one side beyond the opening, an inner surface that slopes inward from the top, and an outer surface that slopes outward from the top, and the valve is in contact with the top but not with the inner surface, thus forming a shock absorber. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a buffer device that can suppress the valve from sticking to the piston. [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 is a diagram showing an example of the general configuration of the piston section. [Figure 3] This figure shows an example of the piston as viewed axially from the second side. [Figure 4] This figure shows an example of a piston viewed axially from the first side. [Figure 5] This is an example of an enlarged view of section V in Figure 2. [Figure 6] This figure shows an example of a cross-section of the second outer projection of the piston according to the second embodiment. [Figure 7](a) is an example of an enlarged view of the second outer projection of the piston according to the third embodiment, viewed axially from the second side. (b) is a diagram showing an example of a cross-section of the second outer projection of the piston according to the third embodiment. [Figure 8] (a) is an example of an enlarged view of the first modified example of the second outer projection when viewed axially from the second side. (b) is a diagram showing an example of a cross-section of the first modified example of the second outer projection. [Figure 9] This is an example of an enlarged view of a second modified example of the second outer projection, as seen from the second side in the axial direction. [Figure 10] This is an example of an enlarged view of the third modified example of the second outer projection, as seen from the second side in the axial direction. [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 hydraulic fluid, and a rod 20 whose second end protrudes from the cylinder portion 10 and whose first end is slidably 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 60 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 the schematic configuration of the piston section 30. Figure 3 shows an example of the piston 100 as viewed axially from the second side. Figure 4 shows an example of the piston 100 as viewed axially from the first side. Figure 5 is an example of an enlarged view of section V in Figure 2. The piston part 30 moves axially as the rod 20 moves. The piston part 30 includes a piston 100 in which a plurality of oil passages described later are formed, an extension-side damping valve group 40 provided on the first side of the piston 100, and a compression-side damping valve group 50 provided on the second side of the piston 100. Further, the piston part 30 includes an annular annular member 31 and a valve stopper 32 arranged on the first side of the extension-side damping valve group 40, a nut 33, and an annular annular member 35 and a valve stopper 36 arranged on the second side of the compression-side damping valve group 50. The piston 100, the extension-side damping valve group 40, the compression-side damping valve group 50, the annular member 31, the valve stopper 32, the annular member 35, and the valve stopper 36 are fastened to the rod 20 by the nut 33.

[0014] (Piston 100) The piston 100 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. The piston 100 is formed, for example, by filling a mold having a predetermined shape with metal powder and sintering the filled metal powder.

[0015] <00​​​​​​​​The through-hole 101 is a cylindrical hole. The first end of the rod 20 passes through the through-hole 101. In this way, the piston 100 is attached to the first end of the rod 20. The direction of the center line of the through-hole 101 is the axial direction of the rod 20. The pressure-side oil passage 102 is composed of an axial through-hole formed on the outside of the through-hole 101. The pressure-side oil passage 102 is an oil passage that enables oil flow between the first oil chamber Y1 and the second oil chamber Y2 during the compression stroke of the buffer device 2. As shown in Figure 3, the pressure-side oil passage 102 is provided at multiple locations (eight locations in Figure 3) at approximately equal intervals in the circumferential direction.

[0017] The extension-side oil passage 103 is composed of an axially inclined through-hole formed on the outside of the through-hole 101. The extension-side oil passage 103 is an oil passage that enables oil flow between the second oil chamber Y2 and the first oil chamber Y1 during the extension stroke of the buffer device 2. As shown in Figure 3, the extension-side oil passage 103 is provided at multiple locations (eight locations in Figure 3) at approximately equal intervals in the circumferential direction. The extension-side oil passage 103 is provided at locations different from those where the compression-side oil passage 102 is provided in the circumferential direction. The extension-side oil passage 103 can be formed, for example, by machining.

[0018] The first inner projection 110 is formed in a substantially annular shape and is provided around the through hole 101. The first inner projection 110 protrudes axially from the first end face 115 on the first side, further toward the first side. The first inner projection 110 contacts the inner portion of the extension damping valve group 40.

[0019] The first outer projection 111 is formed in a substantially annular shape. The first outer projection 111 is formed on the first side, outside the first side opening of the extension side oil passage 103 and inside the compression side oil passage 102. The first outer projection 111 further protrudes axially toward the first side from the first end face 115. The projection height of the first outer projection 111 is slightly (for example, 0.05 mm) higher than that of the first inner projection 110. The first outer projection 111 functions as a seating surface on which the first valve 41 of the extension side damping valve group 40, which will be described later, sits.

[0020] A first inner projection 110 is provided on the inside of the first end face 115, and a first outer projection 111 is provided on the outside of the first end face 115, thereby forming an annular groove 116 that is recessed to the second side from the first inner projection 110 and the first outer projection 111. The groove 116 is connected to the second oil chamber Y2 via the extension oil passage 103.

[0021] As shown in Figure 3, the second inner projection 120 has a substantially annular annular portion and a plurality of (eight in Figure 3) convex portions that project radially from the annular portion. The second inner projection 120 is provided around the through hole 101. Furthermore, the second inner projection 120 protrudes axially toward the second side from the second end face 125 formed on the second side. The second inner projection 120 contacts the inner portion of the compression damping valve group 50.

[0022] The second outer projection 130 is formed in an annular shape. On the second side, the second outer projection 130 is formed outside the second side opening 104 in the compression side oil passage 102 and inside the second side opening 105 in the extension side oil passage 103. The second outer projection 130 further protrudes axially toward the second side from the second end face 125. The projection height of the second outer projection 130 is slightly (for example, 0.05 mm) higher than the projection height of the second inner projection 120. The shape of the second outer projection 130 will be described in detail later.

[0023] A second inner projection 120 is provided on the inside of the second end face 125, and a second outer projection 130 is provided on the outside of the second end face 125, thereby forming a groove 126 that is recessed toward the first side from the second inner projection 120 and the second outer projection 130. The groove 126 is connected to the first oil chamber Y1 via the pressure side oil passage 102.

[0024] (Extension damping valve group 40) The extension damping valve group 40 is constructed by stacking multiple (five in Figure 2) plates made of metal. More specifically, the extension damping valve group 40 has a first valve 41 that sits on the first outer projection 111 of the piston 100, a second valve 42 positioned adjacent to the first valve 41, and a third valve 43 positioned adjacent to the second valve 42. The extension damping valve group 40 also has a fourth valve 44 positioned adjacent to the third valve 43, and a fifth valve 45 positioned adjacent to the fourth valve 44. The first valve 41, second valve 42, third valve 43, fourth valve 44, and fifth valve 45 have through holes 48 formed on the inside for the rod 20 to pass through, and are arranged around the rod 20 in order from the piston 100 toward the first side. The diameter of the through hole 48 is smaller than the inner diameter of the first inner projection 110, and the inner portions of the five valves are fixed between the first inner projection 110 and the annular member 31.

[0025] The first valve 41, second valve 42, third valve 43, and fourth valve 44 are annular in shape, and their outer diameter is larger than the outer diameter of the first outer projection 111 of the piston 100, covering the first side of the groove 116 formed in the piston 100. The fifth valve 45 is annular in shape, and its outer diameter is smaller than that of the fourth valve 44. For example, the outer diameter of the fifth valve 45 can be exemplified as being 2 / 3 of the outer diameter of the fourth valve 44. The fifth valve 45 serves to reinforce the inner portions of the first valve 41, second valve 42, third valve 43, and fourth valve 44, thereby increasing the rigidity of these valves. The number of plates constituting the extension damping valve group 40 is not particularly limited.

[0026] (Compression damping valve group 50) The compression damping valve group 50 is constructed by stacking multiple (six in Figure 2) plates made of metal. More specifically, the compression damping valve group 50 has a first valve 51 that sits on the second outer projection 130 of the piston 100, a second valve 52 positioned adjacent to the first valve 51, and a third valve 53 positioned adjacent to the second valve 52. The compression damping valve group 50 also has a fourth valve 54 positioned adjacent to the third valve 53, a fifth valve 55 positioned adjacent to the fourth valve 54, and a sixth valve 56 positioned adjacent to the fifth valve 55. The first valve 51, second valve 52, third valve 53, fourth valve 54, fifth valve 55, and sixth valve 56 have through holes 58 formed on the inside for the rod 20 to pass through, and are arranged around the rod 20 in order from the piston 100 toward the second side. The diameter of the through-hole 58 is smaller than the inner diameter of the second inner projection 120, and the inner portion of the six valves is fixed between the second inner projection 120 and the valve stopper 36.

[0027] The first valve 51 is annular in shape, and its outer diameter is larger than the outer diameter of the second outer projection 130 of the piston 100, covering the second side of the groove 126 formed in the piston 100. The second valve 52, third valve 53, fourth valve 54, and fifth valve 55 are annular in shape, and their outer diameters are smaller than the outer diameter of the first valve 51 and larger than the outer diameter of the top portion 131, which will be described later. The sixth valve 56 is annular in shape, and its outer diameter is smaller than that of the fifth valve 55. For example, the outer diameter of the sixth valve 56 may be 2 / 3 of that of the fifth valve 55. The sixth valve 56 reinforces the inner portions of the first valve 51, second valve 52, third valve 53, fourth valve 54, and fifth valve 55, thereby increasing the rigidity of these valves.

[0028] The annular member 31 has an outer diameter smaller than the outer diameter of the fifth valve 45. The valve stopper 32 has an outer diameter smaller than the outer diameter of the fifth valve 45 and larger than the outer diameter of the annular member 31. The first valve 41, second valve 42, third valve 43, fourth valve 44, and fifth valve 45 are fixed between the annular member 31 and the valve stopper 32 and the piston 100 by nuts 33. As a result, the inner portions of the first valve 41, second valve 42, third valve 43, fourth valve 44, and fifth valve 45 are supported, and the outer portions become free ends, causing them to flex starting from the outermost part of the annular member 31. The valve stopper 32 then suppresses excessive deformation of the first valve 41, second valve 42, third valve 43, fourth valve 44, and fifth valve 45. The annular member 31 and the valve stopper 32 may be integrally constructed.

[0029] The annular member 35 has an outer diameter smaller than the outer diameter of the sixth valve 56. The valve stopper 36 has an outer diameter smaller than the outer diameter of the sixth valve 56 and larger than the outer diameter of the annular member 35. The first valve 51, second valve 52, third valve 53, fourth valve 54, fifth valve 55, and sixth valve 56 are fixed between the annular member 35 and the valve stopper 36 and the piston 100. As a result, the inner portion (in other words, the inner circumference) of the first valve 51, second valve 52, third valve 53, fourth valve 54, fifth valve 55, and sixth valve 56 is supported (in other words, becomes a fixed end), and the outer portion (in other words, becomes a free end), and flexes starting from the outermost part of the annular member 35. Furthermore, the valve stopper 36 suppresses excessive deformation of the first valve 51, second valve 52, third valve 53, fourth valve 54, fifth valve 55, and sixth valve 56. The annular member 35 and the valve stopper 36 may be integrally constructed.

[0030] Next, the second outer projection 130 of the piston 100 will be described in detail. The second outer projection 130 has a top 131 that protrudes furthest to the second side from the second side opening 104 in the pressure side oil passage 102, an inner surface 132 that slopes inward from the top 131, and an outer surface 133 that slopes outward from the top 131.

[0031] The top portion 131, when cut by a plane parallel to the axial direction (in other words, the direction of the through hole 101), has an arc shape, as shown in Figure 5. The radius R of the top portion 131 can be said to be greater than or equal to a predetermined value. The predetermined value can be said to be the minimum radius of the metal powder used to form the piston 100 by sintering. For example, the predetermined value can be said to be 0.15 (mm).

[0032] The inner surface 132 is the surface extending from the top 131 toward the opening 104 of the pressure-side oil passage 102, and is inclined with respect to the axial direction. As shown in Figure 5, when the angle between the inner surface 132 and the orthogonal surface P perpendicular to the axial direction is denoted as θ1, it can be exemplified that θ1 is between 40 degrees and 70 degrees.

[0033] The outer surface 133 is a surface that extends from the top 131 toward the outermost periphery 140 and is inclined with respect to the axial direction. As shown in Figure 5, when the angle between the outer surface 133 and the orthogonal surface P perpendicular to the axial direction is denoted as θ2, it can be exemplified that θ2 is 10 degrees or more. By having θ2 be 10 degrees or more, it becomes possible to make it difficult for the first valve 51 to come into contact with the outer surface 133, for example, during the extension stroke of the shock absorber 2.

[0034] Furthermore, as shown in Figure 5, when θ3 is the angle between the inner surface 132 and the outer surface 133, it is preferable that θ3 is between 90 degrees and 120 degrees. By having θ3 between 90 degrees and 120 degrees, the shape obtained by cutting the second outer projection 130 with a plane parallel to the axial direction is triangular (however, the apex 131 is arc-shaped), which suppresses a decrease in the strength of the second outer projection 130.

[0035] In the piston portion 30 configured as described above, the protrusion height of the second outer projection 130 is slightly higher than the protrusion height of the second inner projection 120. Therefore, the outer circumference of the first valve 51 that seats on the second outer projection 130 is located on the second side of the inner circumference that contacts the second inner projection 120. Furthermore, because the angle θ1 between the inner surface 132 and the orthogonal surface P is between 40 and 70 degrees, when the first valve 51 seats on the second outer projection 130, the first valve 51 contacts the top 131 but does not easily contact the inner surface 132.

[0036] As described above, the shock absorber 2 comprises a piston 100 that partitions the oil chamber in the cylinder 11 containing oil, and an annular first valve 51 (an example of a valve) arranged such that its inner circumference is supported by the piston 100 and its outer circumference is a free end. The piston 100 has a through hole 101 formed in its center through which the rod 20 passes, and a pressure-side oil passage 102 (an example of an oil passage) for passing oil is formed outside the through hole 101. The piston 100 also has a second inner projection 120 (an example of a base end) that is provided to protrude second to the opening 104 of the pressure-side oil passage 102 (an example of one side in the direction of the centerline) around the through hole 101, and the inner circumference of the first valve 51 comes into contact with it. The piston 100 also has a second outer projection 130 (an example of a seating portion) that is provided to protrude second to the opening 104 outside the pressure-side oil passage 102, and the outer circumference of the first valve 51 sits on it. The second outer projection 130 has a top 131 that protrudes most far to the second side of the opening 104, an inner surface 132 that slopes inward from the top 131, and an outer surface 133 that slopes outward from the top 131. The first valve 51 contacts the top 131 but does not contact the inner surface 132.

[0037] With the above configuration, the first valve 51 contacts the top portion 131 but not the inner surface 132, thus reducing the contact area between the piston 100 and the first valve 51. Therefore, even during the extension stroke, sticking of the first valve 51 to the piston 100 is suppressed. Furthermore, even at low temperatures when the oil viscosity is high, the adsorption force between the first valve 51 and the piston 100 is suppressed when transitioning from the extension stroke to the compression stroke, thus suppressing sticking of the first valve 51 to the piston 100. As a result, the generation of abnormal noise caused by the first valve 51 sticking to the piston 100 can be suppressed.

[0038] Here, if we consider the angle between the orthogonal plane P perpendicular to the direction of the through hole 101 (in other words, the axial direction) and the inner surface 132 as θ1, and the angle between the orthogonal plane P and the outer surface 133 as θ2, then it is desirable that θ1 be greater than θ2. This ensures that the first valve 51 does not come into contact with the inner surface 132 with a high degree of accuracy. For example, it is desirable that θ1 be between 40 degrees and 70 degrees. Furthermore, it is preferable that θ2 be 10 degrees or greater. This prevents the first valve 51 from contacting the outer surface 133 even during the extension stroke.

[0039] Furthermore, the shape of the top portion 131, cut by a plane parallel to the axial direction, should preferably be an arc shape with a radius of 0.15 mm or more. This makes it easier to ensure that the strength of the second outer projection 130 is sufficient to withstand contact with a small contact area, even if the first valve 51 contacts the top portion 131 without contacting the inner surface 132.

[0040] <Second Embodiment> The piston 200 according to the second embodiment differs from the piston 100 according to the first embodiment in that it has a second outer projection 230 corresponding to the second outer projection 130. 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.

[0041] Figure 6 shows an example of a cross-section of the second outer projection 230 of the piston 200 according to the second embodiment. Unlike the second outer projection 130 in the first embodiment, the second outer projection 230 differs in that a groove 235 is formed in the outer surface 233 corresponding to the outer surface 133, recessed toward the first side. The groove 235 is formed in an annular shape on the outside of the top portion 131, extending circumferentially around the entire circumference. The shape of the groove 235 when cut by a plane parallel to the axial direction is a triangle with an acute angle at the bottom, as shown in Figure 6. However, the shape of the groove 235 is not particularly limited. For example, the shape of the groove 235 may be a square or a trapezoid. The size of the groove 235 can be exemplified as being such that the surface area of ​​the outer surface 233 is 1 / 3 or more and 2 / 3 or less of the surface area when the groove 235 is not formed (for example, the surface area of ​​the outer surface 133).

[0042] With the piston 200 configured as described above, even if the first valve 51 comes into contact with the outer surface 233 during the extension stroke of the shock absorber 2, the first valve 51 is prevented from sticking to the outer surface 233. As a result, the generation of abnormal noise caused by the first valve 51 sticking to the piston 200 is suppressed.

[0043] Although Figure 6 illustrates an example in which one groove 235 is formed around the top 131, the groove 235 may be composed of multiple grooves formed around the top 131.

[0044] <Third Embodiment> The piston 300 according to the third embodiment differs from the piston 100 according to the first embodiment in that it has a second outer projection 330 corresponding to the second outer projection 130. The differences from the first embodiment will be described below. The same reference numerals are used for the same parts in the first and third embodiments, and their detailed descriptions will be omitted.

[0045] Figure 7(a) is an example of an enlarged view of the second outer projection 330 of the piston 300 according to the third embodiment, viewed axially from the second side. Figure 7(b) is a diagram showing an example of a cross-section of the second outer projection 330 of the piston 300 according to the third embodiment. Unlike the second outer projection 130 in the first embodiment, the second outer projection 330 differs in that it has recesses 335 formed in the first direction from the outer surface 333 corresponding to the outer surface 133. Multiple recesses 335 (for example, 24) are formed in the circumferential direction on the outside of the top portion 131. As shown in Figure 7(a), the shape of the recesses 335 when viewed in the axial direction is rectangular, and as shown in Figure 7(b), the shape when cut by a plane parallel to the axial direction is rectangular. However, the number and shape of the recesses 335 are not particularly limited. For example, the shape of the recesses 335 when viewed in the axial direction may be circular, trapezoidal, rhombus, or triangular, and the shape when cut by a plane parallel to the axial direction may be trapezoidal or triangular. The size of the recesses 335 can be exemplified as being such that the surface area of ​​the outer surface 333 is 1 / 3 or more and 2 / 3 or less of the surface area when the recesses 335 are not formed (for example, the surface area of ​​the outer surface 133).

[0046] With the piston 300 configured as described above, even if the first valve 51 comes into contact with the outer surface 333 during the extension stroke of the shock absorber 2, the first valve 51 is prevented from sticking to the outer surface 333. As a result, the generation of abnormal noise caused by the first valve 51 sticking to the piston 300 is suppressed.

[0047] Figure 8(a) is an example of an enlarged view of the first modified example of the second outer projection 330, viewed axially from the second side. Figure 8(b) is a diagram showing an example of a cross-section of the first modified example of the second outer projection 330. Figure 9 is an example of an enlarged view of a second modified example of the second outer projection 330, viewed axially from the second side. Figure 10 is an example of an enlarged view of a third modified example of the second outer projection 330, as seen axially from the second side.

[0048] Figures 7(a) and 7(b) illustrate an example in which one recess 335 is formed in the radial direction. However, as shown in Figures 8(a) and 8(b), the recess 335 may be composed of multiple recesses arranged in the radial direction. Furthermore, the multiple recesses 335 formed in the radial direction do not have to be aligned radially, as shown in Figure 9. The circumferential position of the first recess 3351 formed on the outside of the apex 131 and the circumferential position of the second recess 3352 formed on the outside of the first recess 3351 may be different. Furthermore, Figure 7(a) illustrates an example in which the shape of the recess 335, when viewed axially from the second side, is rectangular and the longitudinal sides are parallel to the radial direction. However, as shown in Figure 10, the recess 335 may be formed so that the longitudinal sides are inclined radially. [Explanation of symbols]

[0049] 1...Suspension device, 2...Buffing device, 11...Cylinder, 20...Rod, 30...Piston section, 51...First valve (example of a valve), 100, 200, 300...Piston, 101...Through hole, 102...Compression side oil passage (example of an oil passage), 104...Opening, 120...Second inner projection (example of a base end), 130, 230, 330...Second outer projection (example of a seating section), 131...Top, 132...Inner surface, 133, 233, 333...Outer surface, 235...Groove, 335...Recess, Y1...First oil chamber, Y2...Second oil chamber

Claims

1. A piston that partitions the oil chamber within the cylinder containing the hydraulic fluid, has a through hole formed in the center for a rod to pass through, and has an oil passage formed outside the through hole for the hydraulic fluid to pass through, An annular valve is positioned such that its inner circumference is supported by the piston and its outer circumference is a free end, Equipped with, The piston has a base end that protrudes to one side in the centerline direction from the opening of the oil passage around the through hole and contacts the inner circumference of the valve, and a seating portion that is located outside the oil passage and protrudes to one side from the opening and seats the outer circumference of the valve, the seating portion having a top that protrudes most to one side from the opening, an inner surface that slopes inward from the top, and an outer surface that slopes outward from the top, The valve contacts the top and does not contact the inner surface. Buffer device.

2. When the angle between the orthogonal plane perpendicular to the direction of the through hole and the inner surface is θ1, and the angle between the orthogonal plane and the outer surface is θ2, then θ1 is greater than θ2. The shock absorber according to claim 1.

3. The aforementioned θ1 is between 40 degrees and 70 degrees. The shock absorber according to claim 2.

4. The aforementioned θ2 is 10 degrees or more. The buffer device according to claim 2.

5. The angle between the inner surface and the outer surface is between 90 degrees and 120 degrees. The shock absorber according to claim 1.

6. The shape of the top portion when the through hole is cut by a plane parallel to the direction of the hole is an arc shape with a radius of 0.15 mm or more. The shock absorber according to claim 1.

7. The seating portion has a groove formed in the outer surface that extends in the circumferential direction. The shock absorber according to claim 1.

8. Multiple grooves are formed in the radial direction. The shock absorber according to claim 7.

9. The seating portion has a plurality of recesses formed in the circumferential direction, which are recessed from the outer surface. The shock absorber according to claim 1.

10. Multiple recesses are formed in the radial direction. The buffer device according to claim 9.

Images