JP2017223281A - Shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shock absorber capable of making an attenuation characteristic a choke characteristic, when a piston speed is in a low speed region.SOLUTION: An attenuation force generating mechanism includes: a plurality of passages 62A provided at a piston 16, and for communicating one side chamber and the other side chamber in a cylinder; a plurality of first seats 65A protruding to the outer peripheral side of one surface 60A of the piston 16 so as to surround an opening of the passages 62A, and arranged being separated in the circumferential direction of the piston 16; an annular second seat 66A provided on an inner peripheral side of the one surface 60A of the piston 16 being separated from the first seats 65A; and a disc 53a seated at the first seats 65A and the second seat 66A. At the first seat 65A, a notch 77A is provided at an inside seat part 71A opposing to the second seat 66A.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a shock absorber.

  There is a shock absorber in which a piston is provided with a valve seat having an annular valve seat portion and a fan-shaped valve seat portion provided around the annular valve seat portion, and an orifice including a small notch groove is formed in the fan-shaped valve seat portion. (For example, refer to Patent Document 1).

Japanese Patent Laid-Open No. 1-288643

  In a shock absorber, when the piston speed is in a low speed range, it may be desired to make the damping force characteristic a choke characteristic.

  Therefore, an object of the present invention is to provide a shock absorber capable of making the damping force characteristic a choke characteristic when the piston speed is in a low speed range.

  In order to achieve the above object, according to the present invention, there is provided a damping force generating mechanism provided in a piston, a plurality of passages for communicating one side chamber and the other side chamber in the cylinder, and the passage on the outer peripheral side of one surface of the piston. A plurality of first sheets that are spaced apart from each other in the circumferential direction of the piston, and an annular ring that is provided on the inner circumferential side of one surface of the piston and spaced apart from the first sheet. The second sheet and a disk seated on the first sheet and the second sheet are provided, and the first sheet is configured such that a notch is provided in an inner sheet portion facing the second sheet.

  According to the present invention, it is possible to make the damping force characteristic a choke characteristic when the piston speed is in a low speed range.

It is sectional drawing which shows the shock absorber of one Embodiment which concerns on this invention. It is the fragmentary sectional view which made the piston the cross section by the XX line of Fig.4 (a) which shows the principal part of the buffer of one Embodiment which concerns on this invention. It is a perspective view which shows the piston of the buffer of one Embodiment which concerns on this invention. The piston of the buffer of one embodiment concerning the present invention is shown, (a) is a top view and (b) is a bottom view. It is a characteristic diagram which shows the damping force characteristic of the buffer of one Embodiment which concerns on this invention. It is a top view which shows the piston of the buffer of one Embodiment which concerns on this invention, and the other piston which can make the components before notch formation common.

  An embodiment according to the present invention will be described with reference to the drawings. In the following, for convenience of explanation, the upper side in the drawing is referred to as “upper” and the lower side in the drawing is referred to as “lower”.

  As shown in FIG. 1, the shock absorber 1 of the present embodiment is a so-called double cylinder type hydraulic shock absorber. The cylinder 2 has a cylindrical inner cylinder 3 and an inner diameter larger than that of the inner cylinder 3. It has a bottomed cylindrical outer cylinder 4 provided concentrically so as to cover the cylinder 3. A reservoir chamber 6 is provided between the inner cylinder 3 and the outer cylinder 4.

  The outer cylinder 4 includes a cylindrical body member 11 and a bottom member 12 that closes a lower portion of the body member 11. A mounting eye 13 is fixed to the bottom member 12 on the outer side opposite to the body member 11.

  The shock absorber 1 includes a piston 16 slidably inserted into the inner cylinder 3 of the cylinder 2. The piston 16 provided in the inner cylinder 3 is disposed in the inner cylinder 3 with respect to the upper chamber 17 (one side chamber or the other side chamber) opposite to the bottom member 12 in the axial direction with respect to the piston 16 and the piston 16. It is defined in a lower chamber 18 (another chamber or one chamber) on the bottom member 12 side in the axial direction. In the cylinder 2, an oil liquid L as a working fluid is sealed in the upper chamber 17 and the lower chamber 18 in the inner cylinder 3, and the working fluid is stored in the reservoir chamber 6 between the inner cylinder 3 and the outer cylinder 4. Oil liquid L and gas G are enclosed.

  The shock absorber 1 includes a piston rod 21 having one end disposed in the inner cylinder 3 of the cylinder 2 and connected to the piston 16 and the other end extending to the outside of the cylinder 2. The piston 16 and the piston rod 21 move together. In the expansion stroke in which the piston rod 21 increases the amount of protrusion from the cylinder 2, the piston 16 moves to the upper chamber 17 side. In the contraction stroke in which the piston rod 21 decreases the amount of protrusion from the cylinder 2, the piston 16 moves downward. It moves to the chamber 18 side.

  A rod guide 22 is fitted to the upper end opening side of the inner cylinder 3 and the outer cylinder 4, and a seal member 23 is attached to the outer cylinder 4 on the upper side, which is the outer side of the cylinder 2, relative to the rod guide 22. Yes. Both the rod guide 22 and the seal member 23 are annular. The piston rod 21 is slidably inserted inside the rod guide 22 and the seal member 23, and extends to the outside of the cylinder 2 via the rod guide 22 and the seal member 23. The upper chamber 17 is formed between the piston 16 in the inner cylinder 3 and the rod guide 22.

  The rod guide 22 supports the piston rod 21 such that it can move in the axial direction while restricting its radial movement, and guides the movement of the piston rod 21. The seal member 23 is in close contact with the outer cylinder 4 at the outer peripheral portion thereof, and is in sliding contact with the outer peripheral portion of the piston rod 21 moving in the axial direction at the inner peripheral portion thereof. 4 prevents the gas G and the oil L in the reservoir chamber 6 in the inside 4 from leaking to the outside.

  The rod guide 22 has a step shape in which the outer peripheral portion has a larger diameter at the upper portion than the lower portion. The rod guide 22 is fitted to the inner peripheral portion at the upper end of the inner tube 3 at the lower portion of the small diameter, and the outer tube at the upper portion of the large diameter. 4 is fitted to the inner periphery of the upper part. A base valve 25 that defines a lower chamber 18 and a reservoir chamber 6 is installed on the bottom member 12 of the outer cylinder 4, and the inner peripheral portion of the lower end of the inner cylinder 3 is fitted to the base valve 25. ing. The upper end portion of the outer cylinder 4 is caulked inward in the radial direction to form a caulking portion 26, and the caulking portion 26 and the rod guide 22 sandwich the seal member 23. The lower chamber 18 is formed between the piston 16 in the inner cylinder 3 and the base valve 25.

  The piston rod 21 has a columnar main shaft portion 31 and a columnar mounting shaft portion 32 having a smaller diameter than this, and the end portion of the main shaft portion 31 on the mounting shaft portion 32 side extends in the direction perpendicular to the axis. A shaft step portion 33 is formed. The attachment shaft portion 32 is disposed in the cylinder 2, and a male screw 34 is formed at the end opposite to the main shaft portion 31. The piston 16 is fastened to the mounting shaft portion 32 by a nut 35 screwed into the male screw 34.

  In the shock absorber 1, for example, a protruding portion of the piston rod 21 from the cylinder 2 is arranged at the upper part and supported by the vehicle body, and the mounting eye 13 on the cylinder 2 side is arranged at the lower part and connected to the wheel side. On the contrary, the cylinder 2 side may be supported by the vehicle body, and the piston rod 21 may be connected to the wheel side. When the wheels vibrate as the vehicle travels, the positions of the cylinder 2 and the piston rod 21 change relatively with the vibrations, but the change is suppressed by the fluid resistance of the flow path formed in the piston 16.

  As shown in FIG. 2, the piston 16 has an annular shape with a fitting hole 40 formed through the center, and the fitting shaft portion 32 of the piston rod 21 is fitted in the fitting hole 40. It will be attached to the piston rod 21.

  Between the piston 16 and the shaft step portion 33 of the piston rod 21, a regulating member 51, a small-diameter disc 52, and a valve disc 53 are provided in this order from the shaft step portion 33 side. The valve disc 53 is composed of a plurality of single discs 53a to 53c. A valve disk 55, a small-diameter disk 56, a contact disk 57, and a regulating member 58 are provided in this order from the piston 16 side on the opposite side of the piston 16 from the shaft step portion 33. The valve disk 55 includes a plurality of single disks 55a to 55c. A nut 35 is provided on the opposite side of the regulating member 58 from the piston 16, and the nut 35 sandwiches the parts from the regulating member 51 to the regulating member 58 with the shaft step portion 33.

  The restricting member 51 has an annular shape, and abuts on the shaft step portion 33 in a state where the attachment shaft portion 32 is fitted on the inner peripheral side. The regulating member 51 has an outer diameter larger than the diameter of the shaft step portion 33. The restricting member 51 is thicker and more rigid than the small-diameter disk 52 and the single disks 53a to 53c, both of which are thin plates.

  The small-diameter disk 52 has an annular shape, and the attachment shaft portion 32 is fitted on the inner peripheral side. The small diameter disk 52 has an outer diameter smaller than the diameter of the shaft step portion 33.

  The valve disk 53 is configured by laminating a plurality of single disks 53a to 53c, and each of the single disks 53a to 53c has an annular shape, and the mounting shaft portion 32 is fitted to the inner peripheral side. . In the single disks 53a to 53c, the single disk 53a arranged closest to the piston 16 has a larger outer diameter than the single disk 53b arranged on the opposite side of the piston 16, and the single disk 53b The outer diameter is larger than that of the single disk 53c arranged on the side opposite to the piston 16. That is, the single disks 53a to 53c constituting the valve disk 53 have a larger outer diameter on the piston 16 side.

  In the valve disk 53, the outer diameter of the single disk 53 c that is the minimum outer diameter is larger than the outer diameter of the small-diameter disk 52 and smaller than the outer diameter of the regulating member 51. In the valve disc 53, the outer diameter of the single disc 53 a that is the maximum outer diameter is larger than the outer diameter of the regulating member 51.

  The valve disk 55 is configured by laminating a plurality of single disks 55a to 55c, and each of the single disks 55a to 55c has an annular shape, and the mounting shaft portion 32 is fitted to the inner peripheral side. . In the single disks 55a to 55c, the single disk 55a arranged closest to the piston 16 has a larger outer diameter than the single disk 55b arranged on the opposite side of the piston 16, and the single disk 55b The outer diameter is larger than that of the single disk 55c disposed on the side opposite to the piston 16. That is, the single disks 55a to 55c constituting the valve disk 55 have a larger outer diameter on the piston 16 side.

  Here, the single disks 53a and 55a are common parts, the single disks 53b and 55b are also common parts, and the single disks 53c and 55c are also common parts.

  The small-diameter disk 56 has an annular shape, and the mounting shaft portion 32 is fitted on the inner peripheral side. The small diameter disk 56 has an outer diameter smaller than that of the single disk 55c. The contact disk 57 has an annular shape, and the mounting shaft portion 32 is fitted to the inner peripheral side. The contact disk 57 has an outer diameter larger than the outer diameter of the small-diameter disk 56, and is equal to the outer diameter of the single disk 55c.

  The restricting member 58 has an annular shape, and the mounting shaft portion 32 is fitted on the inner peripheral side. The regulating member 58 has an outer diameter smaller than the outer diameter of the contact disk 57 and larger than the outer diameter of the small diameter disk 56. The restricting member 58 is thicker than the single discs 55a to 55c, the small-diameter disc 56, and the contact disc 57, which are all thin plates, and has high rigidity.

  A regulating member 51, a small diameter disk 52, a valve disk 53, a piston 16, a valve disk 55, a small diameter disk 56, an abutting disk 57, and a regulating member 58 are stacked in this order on the shaft step portion 33 of the piston rod 21 to attach the mounting shaft. When the nut 35 is screwed onto the male screw 34 of the portion 32, these are clamped in the axial direction by being sandwiched between the shaft step portion 33 and the nut 35. At this time, the valve disk 53 having a larger diameter than the small diameter disk 52 is clamped between the small diameter disk 52 and the piston 16, so that a portion of the valve disk 53 radially outside the small diameter disk 52 extends from the piston 16. It can be deformed in the direction of separation. Further, the valve disc 55 having a larger diameter than the small diameter disc 56 is clamped between the small diameter disc 56 and the piston 16, so that a portion of the valve disc 55 radially outside the small diameter disc 56 is separated from the piston 16. It is possible to deform in the direction to do.

  Here, the front and back surfaces of the piston 16 have the same shape, and can be attached to the piston rod 21 without distinction between the front and back surfaces. Hereinafter, for convenience of explanation, the surface on the valve disc 53 side is referred to as a surface 60A (one surface), the passage opened and closed by the valve disc 53 is referred to as a passage 62A, and the surface on the valve disc 55 side is referred to as a surface 60B (one surface). The passage opened and closed at 55 will be described as passage 62B.

  The passage 62 </ b> A penetrates the piston 16 in the axial direction outside the radial fitting hole 40 of the piston 16, and the passage 62 </ b> B is located outside the radial fitting hole 40 of the piston 16. 16 is penetrated in the axial direction. As a result, the passages 62A and 62B are provided in the piston 16 to allow the upper chamber 17 and the lower chamber 18 to communicate with each other.

  As shown in FIG. 3, a plurality of passages 62 </ b> A (specifically, four places) are formed in the piston 16, and these passages 62 </ b> A match the distance from the central axis of the piston 16 and It is arranged at equal intervals in the direction. The passage 62B is also formed in the piston 16 at a plurality of locations (specifically, four locations), and these passages 62B are arranged at equal intervals in the circumferential direction of the piston 16 with the distance from the central axis of the piston 16 being matched. ing. The plurality of passages 62 </ b> A and the plurality of passages 62 </ b> B are arranged alternately at equal intervals in the circumferential direction of the piston 16 with the distance from the central axis of the piston 16 being matched.

  The surface 60A of the piston 16 has a main surface 64A extending in the direction perpendicular to the axis, and the surface 60A includes a plurality of (specifically, four) protruding outward in the axial direction from the main surface 64A so as to surround the opening of the passage 62A. 1st sheet 65A is provided. Here, the number of passages 62A is the same as the number of first sheets 65A, and one passage 62A is provided inside one first sheet 65A. However, the number of passages 62A is the same as the number of first sheets 65A. The plurality of passages 62 </ b> A may be provided inside one first sheet 65 </ b> A. The plurality of first sheets 65 </ b> A have the same shape, and are arranged on the outer peripheral side of the surface 60 </ b> A of the piston 16 at equal intervals in the circumferential direction of the piston 16 with the distance from the central axis of the piston 16. Yes.

  Further, on the inner peripheral side of the surface 60A, an annular second sheet 66A that protrudes outward in the axial direction from the main surface 64A is provided apart from the first sheet 65A in the radial direction of the piston 16. The second sheet 66 </ b> A has an annular shape, and the outer peripheral surface 67 </ b> A is a cylindrical surface centered on the central axis of the piston 16. A fitting hole 40 having a circular cross section around the central axis of the piston 16 is provided on the inner peripheral side of the second sheet 66A. Therefore, as shown in FIG. 2, the second sheet 66 </ b> A is coaxial with the piston rod 21 that is coaxially fitted in the fitting hole 40. As shown in FIG. 4A, the outer peripheral surface 67A of the second sheet 66A is separated from all the first sheets 65A over the entire periphery.

  The first sheet 65A is disposed on the second sheet 66A side in the radial direction of the piston 16 and faces the second sheet 66A, and the outer sheet part 72A is disposed on the opposite side of the second sheet 66A. And a pair of connecting sheet portions 73A for connecting them. The inner sheet portion 71A has an arc shape that is coaxial with the second sheet 66A, and a facing surface 75A that faces the outer peripheral surface 67A is a part of a cylindrical surface that is coaxial with the outer peripheral surface 67A. The first sheet 65A is symmetric with respect to a line passing through the passage 62A arranged inside the first sheet 65A and the central axis of the piston 16, and the pair of connecting sheet portions 73A of the first sheet 65A are Parallel to the line, the outer sheet portion 72A of the first sheet 65A is orthogonal to the line.

  In the first sheet 65 </ b> A, a notch 77 </ b> A that penetrates the inner sheet portion 71 </ b> A in the radial direction of the piston 16 is provided in the inner sheet portion 71 </ b> A that faces the second sheet 66 </ b> A in the radial direction of the piston 16. The notch 77A is formed in the center of the inner sheet portion 71A by, for example, coining. The front end surface on the protruding side of the portion excluding the notch 77A of the first sheet 65A and the front end surface on the protruding side of the second sheet 66A have the same height in the axial direction of the piston 16.

  As shown in FIG. 4B, the piston 16 is provided with a main surface 64B similar to the main surface 64A on the surface 60B (one surface) on the other side in the axial direction. In addition, a plurality of (specifically four) first sheets 65B similar to the first sheet 65A protrude from the main surface 64B on the piston 16 so as to surround the opening of the passage 62B on the outer peripheral side of the surface 60B. Is provided. Also, a second sheet 66B similar to the second sheet 66A is provided on the inner peripheral side of the surface 60B so as to protrude from the main surface 64B, being spaced from the first sheet 65B in the radial direction of the piston 16.

  The first sheet 65B includes an inner sheet portion 71B similar to the inner sheet portion 71A, an outer sheet portion 72B similar to the outer sheet portion 72A, and a pair of connection sheet portions 73B similar to the pair of connection sheet portions 73A. doing. Therefore, in the inner sheet portion 71B, a facing surface 75B similar to the facing surface 75A faces the outer peripheral surface 67B of the second sheet 66B, and a notch 77B similar to the notch 77A causes the inner sheet portion 71B to be connected to the piston 16. Are formed so as to penetrate in the radial direction.

  As shown in FIG. 2, the single disk 53a closest to the piston 16 of the valve disk 53 is seated on the plurality of first seats 65A and second seats 66A. As shown in FIG. 4A, the single disk 53a has a radius larger than the maximum distance from the center of the piston 16 of the first sheet 65A so as to cover the entire plurality of first sheets 65A. Thus, the plurality of first seats 65A and second seats 66A are seated.

  At the time of the seating, the second sheet 66A is in contact with the single disk 53a over the entire circumference on the projecting side, and the first sheet 65A is located on the entire projecting side of the inner sheet 71A excluding the notch 77A. Comes into contact with the single disk 53a. Thereby, a chamber 78A that is surrounded by the first sheet 65A, the main surface 64A, and the single disk 53a and communicates with the passage 62A is formed. Further, the circumferential direction extending in the circumferential direction of the piston 16 is surrounded by the facing surface 75A of the inner sheet portion 71A of the first sheet 65A, the outer circumferential surface 67A of the second sheet 66A, the main surface 64A, and the single disk 53a. A passage 80A is formed. Furthermore, an orifice 81A that is surrounded by the notch 77A and the single disk 53a and penetrates the inner sheet portion 71A in the radial direction of the piston 16 is formed. The orifice 81A allows the chamber 78A and the circumferential passage 80A to communicate with each other. The circumferential passage 80A opens to the upper chamber 17 at both ends opposite to the orifice 81A. The passage sectional area of the circumferential passage 80A is substantially equal to the passage sectional area of the orifice 81A.

  Therefore, as shown in FIG. 2, in the state where the single disk 53a is seated on the first seat 65A, the oil liquid L introduced into the passage 62A from the lower chamber 18 in the contraction stroke is narrower than the passage cross-sectional area of the passage 62A. It is squeezed by 81A, flows in the circumferential passage 80A for a predetermined distance while being substantially squeezed, and is discharged into the upper chamber 17. Further, in a state where the valve disk 53 including the single disk 53a is separated from the first seat 65A, the oil L introduced into the passage 62A from the lower chamber 18 in the contraction stroke is between the valve disk 53 and the first seat 65A. It is discharged into the upper chamber 17 through the gap. At this time, a damping force corresponding to the cross-sectional area of the gap is generated in the shock absorber 1. A plurality of passages 62A, a plurality of first sheets 65A, a second sheet 66A, and a valve disk 53 including a single disk 53a are provided in the piston 16 to control the flow of the oil L and generate a damping force. A compression-side damping force generation mechanism 85A is configured.

  The single disc 55a closest to the piston 16 of the valve disc 55 is seated on the plurality of first seats 65B and second seats 66B. As shown in FIG. 4B, the single disk 55a has a radius larger than the maximum distance from the center of the piston 16 of the first sheet 65B, and covers the entire plurality of first sheets 65B. Thus, the plurality of first seats 65B and second seats 66B are seated.

  At the time of sitting, the second sheet 66B is in contact with the single-piece disk 55a over the entire circumference on the protruding side, and the first sheet 65B is on the entire protruding side of the inner sheet 71B excluding the notch 77B. Comes into contact with the single disk 55a. As a result, a chamber 78B that is surrounded by the first sheet 65B, the main surface 64B, and the single disk 55a and communicates with the passage 62B is formed. Further, a circumferential direction extending in the circumferential direction of the piston 16 is surrounded by the facing surface 75B of the inner sheet portion 71B of the first sheet 65B, the outer circumferential surface 67B of the second sheet 66B, the main surface 64B, and the single disc 55a. A passage 80B is formed. Furthermore, an orifice 81B that is surrounded by the notch 77B and the single disk 55a and penetrates the inner sheet portion 71B in the radial direction of the piston 16 is formed. The orifice 81B allows the chamber 78B and the circumferential passage 80B to communicate with each other. Both ends of the circumferential passage 80B opposite to the orifice 81B open to the lower chamber 18. The passage sectional area of the circumferential passage 80B is substantially equal to the passage sectional area of the orifice 81A.

  Therefore, as shown in FIG. 2, in the state where the single disk 55a is seated on the first seat 65B, the oil liquid L introduced into the passage 62B from the upper chamber 17 in the extension stroke is narrower than the passage sectional area of the passage 62B. It is squeezed by 81B, flows in the circumferential direction passage 80B for a predetermined distance with substantially the squeezed passage cross-sectional area, and is discharged into the lower chamber 18. Further, in a state where the valve disk 55 including the single disk 55a is separated from the first seat 65B, the oil L introduced into the passage 62B from the upper chamber 17 in the extending stroke is between the valve disk 55 and the first seat 65B. It is discharged into the lower chamber 18 through the gap. At this time, a damping force corresponding to the cross-sectional area of the gap is generated in the shock absorber 1. A plurality of passages 62B, a plurality of first sheets 65B, a second sheet 66B, and a valve disk 55 including a single disk 55a are provided in the piston 16 to control the flow of the oil liquid L and generate a damping force. An extension-side damping force generation mechanism 85B is configured.

  As shown in FIG. 1, the above-described base valve 25 is provided between the bottom member 12 of the outer cylinder 4 and the inner cylinder 3. The base valve 25 includes a base valve member 101 that partitions the lower chamber 18 and the reservoir chamber 6, a damping valve 102 provided below the base valve member 101, that is, the reservoir chamber 6 side, and an upper side of the base valve member 101. That is, it has the suction valve 103 provided in the lower chamber 18 side, and the attachment pin 104 which attaches the damping valve 102 and the suction valve 103 to the base valve member 101.

  The base valve member 101 has an annular shape, and a mounting pin 104 is fitted on the inner peripheral side. The base valve member 101 includes a plurality of passages 105 through which the oil L flows between the lower chamber 18 and the reservoir chamber 6, and the lower chamber 18 outside the passages 105 in the radial direction of the base valve member 101. A plurality of passages 106 through which the oil liquid L is circulated with the reservoir chamber 6 are formed. The damping valve 102 on the reservoir chamber 6 side allows the flow of the oil liquid L from the lower chamber 18 to the reservoir chamber 6 via the passage 105, while the oil liquid L passes through the passage 105 from the reservoir chamber 6 to the lower chamber 18. Suppress the flow. The suction valve 103 allows the flow of the oil liquid L from the reservoir chamber 6 to the lower chamber 18 through the passage 106, while suppressing the flow of the oil liquid L from the lower chamber 18 to the reservoir chamber 6.

  The damping valve 102 opens in the contraction stroke of the shock absorber 1 to flow the oil L from the lower chamber 18 to the reservoir chamber 6 and generate a damping force. The suction valve 103 is opened during the expansion stroke of the shock absorber 1 to flow the oil L from the reservoir chamber 6 into the lower chamber 18. The suction valve 103 allows the liquid to flow from the reservoir chamber 6 to the lower chamber 18 without substantially generating a damping force so as to compensate for the shortage of the liquid mainly caused by the extension of the piston rod 21 from the inner cylinder 3. Fulfills the function.

  In the shock absorber 1 of the present embodiment, in the extension stroke, the pressure of the upper chamber 17 is increased and the pressure of the lower chamber 18 is decreased by the movement of the piston 16, and the oil liquid L in the upper chamber 17 passes through the plurality of passages 62 </ b> B. Through the lower chamber 18 side. When the piston speed, which is the moving speed of the piston 16, is low, the oil L in the upper chamber 17 remains in a state where the valve disk 55 is seated on the first seat 65B from the plurality of passages 62B as shown in FIG. The flow into the lower chamber 18 flows through the orifice 81B having a narrow passage cross-sectional area and the circumferential passage 80B, and thus the flow into the lower chamber 18 is suppressed. When the piston speed is low, the damping force generation mechanism 85B causes the oil L after the oil is introduced into the passage 62B from the upper chamber 17 and passed through the orifice 81B as shown in FIG. Since it flows into the lower chamber 18 via the circumferential passage 80B extending in the circumferential direction, the oil liquid L moves a long distance with the passage cross-sectional area being narrow. Therefore, the damping force generating mechanism 85B has a choke characteristic (a characteristic in which the damping force is substantially proportional to the piston speed) when the piston speed is in a predetermined low speed range 0 to V1, as indicated by a solid line Y1 in FIG. ) Damping force is generated.

  Further, when the piston speed becomes faster than the above, the oil L in the upper chamber 17 shown in FIG. 2 causes the valve disc 55 and the first seat to move away from the first seat 65B from the plurality of passages 62B. It flows to the lower chamber 18 through the gap with 65B, and thus the flow to the lower chamber 18 is suppressed. At this time, the damping force generation mechanism 85B causes the oil L to flow according to the valve opening amount from the first seat 65B of the valve disk 55 that changes according to the piston speed, and therefore, as shown by the solid line Y2 in FIG. When the piston speed is in a predetermined high speed range V1 to V1, the shock absorber 1 has a valve characteristic (a characteristic in which the damping force is substantially proportional to the piston speed. (A small characteristic) damping force is generated.

  In the contraction stroke, the movement of the piston 16 shown in FIG. 2 increases the pressure in the lower chamber 18 and decreases the pressure in the upper chamber 17, and the oil L in the lower chamber 18 passes through the plurality of passages 62 </ b> A. Try to flow to the side. When the piston speed is low, the oil liquid L in the lower chamber 18 has an orifice 81A and a circumferential passage 80A having a narrow passage cross-sectional area from the plurality of passages 62A while the valve disk 53 is seated on the first seat 65A. Therefore, the flow to the upper chamber 17 is suppressed, and thus the flow to the upper chamber 17 is suppressed. When the piston speed is low, the damping force generation mechanism 85A causes the oil L after being introduced from the lower chamber 18 to the passage 62A and passing through the orifice 81A as shown in FIG. Since it flows into the upper chamber 17 via the circumferential passage 80A extending in the circumferential direction, the oil liquid L moves a long distance with the passage cross-sectional area being narrow. Therefore, when the piston speed is in the low speed region, the damping force generation mechanism 85A generates a damping force having a choke characteristic in the shock absorber 1 as in the extension stroke.

  Further, when the piston speed becomes faster than the above, the oil liquid L in the lower chamber 18 shown in FIG. 2 causes the valve disc 53 and the first seat to move away from the first seat 65A from the plurality of passages 62A. It flows into the upper chamber 17 through the gap with 65A, and thus the flow to the upper chamber 17 is suppressed. At this time, since the damping force generation mechanism 85A causes the oil liquid L to flow according to the valve opening amount from the first seat 65A of the valve disk 53 that changes according to the piston speed, when the piston speed is in the high speed range, Similarly to the extension stroke, the damping force of the valve characteristic is generated in the shock absorber 1.

  The shock absorber of Patent Document 1 described above is provided with a valve seat having an annular valve seat portion and a plurality of fan-shaped valve seat portions provided around the annular valve seat portion on the piston. An orifice composed of a small notch groove is formed on the side opposite to the valve seat portion, and the working fluid passing through the orifice is directly discharged into a wide cylinder chamber. In such a shock absorber, as indicated by a two-dot chain line Z1 in FIG. 5, when the piston speed is in the low speed range 0 to V1, the orifice characteristic (a characteristic in which the damping force is approximately proportional to the square of the piston speed) is attenuated. Force will be generated.

  On the other hand, in the shock absorber 1 of the present embodiment, a plurality of first sheets 65B each surrounding the opening of the passage 62B are arranged on the outer peripheral side of the surface 60B of the piston 16 so as to be separated from each other in the circumferential direction of the piston 16. An annular second sheet 66B is provided on the inner peripheral side of the surface 60B of the piston 16 so as to be separated from the plurality of first sheets 65B, and is cut into an inner sheet portion 71B facing the second sheet 66B of each first sheet 65B. A notch 77B is provided. For this reason, in the extension stroke, when the piston speed is low, the oil L as the working fluid passes through the passage 62B from the upper chamber 17 and passes through the orifice 81B between the notch 77B and the single disc 55a. The sheet is discharged to the lower chamber 18 after passing through the circumferential passage 80B between the sheet 66B and the inner sheet portion 71B. As described above, when the piston speed is in the low speed region, the oil liquid L that has been introduced from the upper chamber 17 into the passage 62B and passed through the orifice 81B flows into the lower chamber 18 via the circumferential passage 80B. L travels a long distance with the passage cross-sectional area being narrow. Thereby, as indicated by a solid line Y1 in FIG. 5, a damping force having a choke characteristic can be generated in the low speed range 0 to V1 of the piston speed.

  Similarly, on the outer peripheral side of the surface 60A of the piston 16, a plurality of first sheets 65A each surrounding the opening of the passage 62A are arranged apart from each other in the circumferential direction of the piston 16, and on the inner peripheral side of the surface 60A of the piston 16 An annular second sheet 66A is provided apart from the plurality of first sheets 65A, and a notch 77A is provided in the inner sheet portion 71A facing the second sheet 66A of each first sheet 65A. Therefore, in the contraction stroke, when the piston speed is low, the oil L passing through the passage 62A from the lower chamber 18 and passing through the orifice 81A between the notch 77A and the single disk 53a is transferred to the second sheet 66A and the inner side. It is discharged into the upper chamber 17 after passing through the circumferential passage 80A between the sheet portion 71A. As described above, when the piston speed is in the low speed region, the oil liquid L introduced into the passage 62A from the lower chamber 18 and passing through the orifice 81A is caused to flow to the upper chamber 17 via the circumferential passage 80A. L moves a long distance with the passage cross-sectional area being narrow. Thereby, when the piston speed is in a low speed region, a damping force having a choke characteristic can be generated.

  Here, the choke characteristics can be changed by changing the width and number of the notches 77A and 77B. Since the notches 77A and 77B are formed by coining, the width and number can be easily changed.

  Further, the piston 16 can be shared with a shock absorber that generates a damping force having an orifice characteristic when the piston speed is in a low speed range until the state before the notches 77A and 77B are formed. Then, for this common member, if the notch 77A is provided in the inner sheet portion 71A, the piston 16 of the above embodiment is obtained, and as shown in FIG. 6, if the notch 77A ′ is provided in the outer sheet portion 72A, The shock absorber piston 16 'generates a damping force having an orifice characteristic.

  The embodiment described above includes a cylinder filled with a working fluid, a piston that is slidably inserted into the cylinder and defines the inside of the cylinder as one side chamber and another side chamber, and is connected to the piston. A piston rod extending to the outside of the cylinder; and a damping force generation mechanism that is provided on the piston and generates a damping force by controlling a flow of a working fluid. The damping force generation mechanism is provided on the piston. A plurality of passages communicating with the one-side chamber and the other-side chamber, and a plurality of passages that protrude on the outer peripheral side of one surface of the piston so as to surround the opening of the passage and are spaced apart in the circumferential direction of the piston. A first seat, an annular second seat provided apart from the first seat on an inner peripheral side of one surface of the piston, and a disc seated on the first seat and the second seat; For example, the first sheet is disposed notches in the inner sheet portion facing the second sheet. A plurality of first sheets surrounding the opening of the passage are arranged on the outer peripheral side of the one surface of the piston so as to be spaced apart from each other in the circumferential direction of the piston. A sheet is provided, and a notch is provided in the inner sheet portion facing the second sheet of the first sheet. For this reason, when the piston speed is low, the working fluid passing through the passage and between the notch and the disk passes between the second sheet and the inner sheet part. As a result, the working fluid moves a long distance in a state where the passage cross-sectional area is narrow, so that a damping force having a choke characteristic can be generated.

1 shock absorber 2 cylinder 16 piston 17 upper chamber (one side chamber or other side chamber)
18 Lower room (other room or one room)
21 Piston rod 53a, 55a Disc (disc)
60A, 60B side (one side)
62A, 62B Passage 65A, 65B First sheet 66A, 66B Second sheet 71A, 71B Inner sheet part 77A, 77B Notch 85A, 85B Damping force generation mechanism

Claims (1)

A cylinder filled with a working fluid;
A piston that is slidably inserted into the cylinder and defines the inside of the cylinder into one side chamber and another side chamber;
A piston rod connected to the piston and extending to the outside of the cylinder;
A damping force generating mechanism provided on the piston for generating a damping force by controlling the flow of the working fluid;
The damping force generation mechanism is
A plurality of passages provided in the piston for communicating the one-side chamber and the other-side chamber;
A plurality of first sheets that protrude on the outer peripheral side of one surface of the piston so as to surround the opening of the passage, and are spaced apart in the circumferential direction of the piston;
An annular second sheet provided on the inner peripheral side of one surface of the piston and spaced from the first sheet;
A disc seated on the first seat and the second seat;
With
The shock absorber according to claim 1, wherein the first sheet is provided with a notch in an inner sheet portion facing the second sheet.

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