Buffer

Abstract

To provide a buffer capable of realizing both a low valve characteristic and a high valve durability.SOLUTION: A contraction side damping force mechanism 31 has: a first valve body 41; a second valve body 51 having lower rigidity than the first valve body 41; a chamber 63 formed between the first valve body 41 and the second valve body 51; and a notch 62 communicating the inside and outside of the chamber 63. With this configuration, even when the pressure in a first chamber increases with the increase in piston speed during an extension stroke, it is possible to prevent the second valve body 51 from being pushed toward a piston 3 by the pressure (back pressure) in the first chamber and being damaged, thereby realizing both a low valve characteristic and a high valve durability.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a shock absorber that generates a damping force by utilizing the flow of a working fluid. [Background technology]

[0002] Patent Document 1 discloses a shock absorber (hereinafter referred to as a "conventional shock absorber") that opens and closes a piston passage with a valve formed by stacking a plurality of discs. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-015640 Summary of the Invention [Problem to be solved by the invention]

[0004] In a conventional shock absorber, for example, when the compression valve characteristic is set low, it is necessary to reduce the number of stacked discs that make up the compression valve provided in the compression piston passage. In this case, the pressure (back pressure) in the first oil chamber increases during the extension stroke, which can damage the compression valve.

[0005] An object of the present invention is to provide a shock absorber that achieves both low valve characteristics and high valve durability. [Means for solving the problem]

[0006] In the shock absorber of the present invention, the damping force mechanism includes a first valve member that is arranged so as to be able to come into contact with the piston and is movable in the axial direction, a second valve member that is arranged further away from the piston than the first valve member and has lower rigidity than the first valve member, a chamber formed between the first valve member and the second valve member, and a chamber passage that connects the inside and outside of the chamber. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a shock absorber that achieves both low valve characteristics and high valve durability. [Brief explanation of the drawings]

[0008] [Figure 1] 2 is a view showing a part of a cross section of the shock absorber according to the first embodiment taken along an axial plane. FIG. [Figure 2] FIG. 2 is an enlarged view of a main part of FIG. 1. [Figure 3] FIG. 2 is an explanatory diagram of the first embodiment, being a plan view of a second valve body of the compression stroke damping force mechanism. [Figure 4] 4 is a cross-sectional view taken along the line AA in FIG. 3. [Figure 5] FIG. 10 is an explanatory diagram of a second embodiment, corresponding to FIG. 2. [Figure 6] FIG. 10 is an explanatory diagram of the second embodiment, and is a plan view of the second valve body of the compression stroke damping force mechanism. [Figure 7] FIG. 10 is a diagram showing another configuration of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] (First embodiment) A first embodiment of the present invention will be described with reference to the accompanying drawings. For convenience, the up-down direction in Fig. 1 will be referred to as the "up-down direction" as it is. As shown in Fig. 1, shock absorber 1 has a cylinder 2 filled with a working fluid, and a piston 3 slidably fitted in cylinder 2 and dividing the interior of cylinder 2 into a first chamber 2A and a second chamber 2B.

[0010] The piston 3 has an extension-side passage 5 whose upper end opens to the first chamber 2A and a compression-side passage 6 whose lower end opens to the second chamber 2B. The piston 3 has an annular groove 7 provided at the lower end of the piston 3 and connected to the extension-side passage 5, and an annular groove 8 provided at the upper end of the piston 3 and connected to the compression-side passage 6. The extension-side passage 5 opens further outward than the annular groove 8 of the piston 3, and the compression-side passage 6 opens further outward than the annular groove 7 of the piston 3.

[0011] The shock absorber 1 has a piston rod 10 whose first end 11 (small diameter shaft portion) is connected to the piston 3 and whose second end (not shown) extends to the outside from the cylinder 2. A free piston (not shown) that is movable up and down within the cylinder 2 is provided within the cylinder 2. The free piston divides the interior of the cylinder 2 into a second chamber 2B on the piston 3 side (upper side) in which hydraulic oil is sealed as a working fluid, and a gas chamber (not shown) on the bottom side (lower side).

[0012] The shock absorber 1 has an extension-side damping force mechanism 21 that is provided in the extension-side passage 5 and opens when hydraulic oil moves from the first chamber 2A to the second chamber 2B. The extension-side damping force mechanism 21 has a seat portion 22 formed on the outer peripheral edge portion of the annular groove 7 of the piston 3, and a valve element 25 whose inner peripheral edge portion is sandwiched between the inner peripheral portion 4 of the piston 3 and a spacer 23 and whose outer peripheral edge portion is seated on the seat portion 22 so as to be able to be released from the seat.

[0013] The valve element 25 is formed by stacking multiple annular discs (reference numerals omitted). Among the multiple stacked discs, those that can abut against the seat portion 22 have multiple (shown as "two" in FIG. 1 ) notches 26 (orifices) formed on the outer periphery thereof, connecting the extension-side passage 5 and the second chamber 2B. A retainer 24 is interposed between the spacer 23 and the washer 12. A retainer 27 is interposed between the valve element 25 and the inner periphery 4 of the piston 3.

[0014] 1 or 2, the shock absorber 1 has a compression-side damping force mechanism 31 that is provided in the compression-side passage 6 and that opens when hydraulic oil moves from the second chamber (one chamber) to the first chamber 2A (the other chamber). The compression-side damping force mechanism 31 has a seat portion 32 formed on the outer peripheral edge of the annular groove 8 of the piston 3, and a valve element 33 whose outer peripheral edge is removably seated on the seat portion 32. The valve element 33 has a first valve element 41 (first valve member) that can come into contact with the seat portion 32 (piston 3), and a second valve element 51 (second valve member) that is positioned further away from the piston 3 than the first valve element 41.

[0015] First valve body 41 has a plurality of discs 42 (shown as "two" in FIG. 2) arranged on the piston 3 side (shown as "lower side" in FIG. 2) and a disc 43 stacked on top of disc 42 on the second valve body 51 side (shown as "upper side" in FIG. 2). Discs 42 and 43 are made of circular plate material having the same outer diameter and inner diameter, and disc 43 has higher rigidity than disc 42. Of the plurality of stacked discs 42, disc 42 that can abut against seat portion 22 has a plurality of notches 44 (shown as "two" in FIG. 2) formed in the outer peripheral edge portion thereof that connects compression-side passage 6 and first chamber 2A.

[0016] The first valve body 41 (disks 42, 43) is provided concentrically with the circular first valve body 41 and has an axial hole 45 through which the collar 34 is slidably inserted. That is, the first valve body 41 is movable in the axial direction (the "up and down direction" in FIG. 2) relative to the collar 34. The first end 11 of the piston rod 10 is slidably inserted into the axial hole 35 of the collar 34. That is, the collar 34 is movable in the axial direction (the "up and down direction" in FIG. 2) relative to the first end 11 of the piston rod 10.

[0017] The second valve body 51 is formed by stacking multiple discs (shown as "three" in FIG. 2). The second valve body 51 is formed from a circular plate material having the same outer diameter as the first valve body 41 (discs 42, 43). The second valve body 51 has an axial hole 55 through which the first end portion 11 of the piston rod 10 is slidably inserted. In other words, the second valve body 51 is movable in the axial direction (the "up and down direction" in FIG. 2) relative to the first end portion 11 of the piston rod 10. The second valve body 51 has lower rigidity than the first valve body 41.

[0018] Between the piston 3 and the washer 13, in this order from the piston 3 side (the "lower side" in FIG. 2), there are interposed the collar 34, the inner peripheral portion 52 of the second valve body 51, the spacer 53, and the inner peripheral portion of the retainer 54. By tightening the nut 15 that is threaded onto the threaded portion 14 formed on the lower end of the first end 11 of the piston rod 10, the collar 34, the inner peripheral portion 52 of the second valve body 51, the spacer 53, and the inner peripheral portion of the retainer 54 are clamped and pressed between the piston 3 and the spacer 13.

[0019] An annular elastic member 37 (first biasing member) is interposed between the inner periphery of the first valve body 41 (first valve member) and the second valve body 51 (second valve member) to bias the first valve body 41 and the second valve body 51 in the axial direction (the "upward direction" in FIG. 2). On the other hand, an annular elastic member 38 is interposed between the inner periphery 46 of the first valve body 41 and the flange portion 36 formed at the lower end of the collar 34 to bias the first valve body 41 in the axial direction (the "upward direction" in FIG. 2). In the first embodiment, seal rings are used as the elastic members 37, 38.

[0020] The elastic members 37, 38 are compressed by tightening the nut 15 that is threaded onto the threaded portion 14 of the piston rod 10. That is, the inner peripheral portion 46 of the first valve body 41 is sandwiched between the elastic members 37, 38 in the axial direction. In other words, the first valve body 41 can move in the axial direction (the "up and down direction" in FIG. 2) by elastically deforming the elastic members 37, 38. In the first embodiment, the elastic forces of the elastic members 37, 38 are adjusted to minimize the axial biasing force of the elastic members 37, 38 on the first valve body 41, and thereby the initial opening pressure of the valve body 33 of the compression-side damping force mechanism 31 is set (adjusted) by the second valve body 51 (second valve member).

[0021] An annular protrusion 61 (chamber forming portion) is formed integrally with the disk 43 on the outer peripheral edge of the disk 43 of the first valve body 41 and protrudes toward the second valve body 51 (the "upward side" in FIG. 2). The protrusion 61 has a semicircular cross section taken along a plane including the center line of the piston 3, and its top abuts against an abutment portion 57 formed on the outer peripheral edge of the second valve body 51. As a result, an annular chamber 63 is formed in the valve body 33, which is defined by the first valve body 41, the second valve body, the elastic member 37 (first biasing member), and the protrusion 61.

[0022] 2 to 4, the protruding portion 61 (chamber forming portion) is formed with a plurality (four notches 62 in FIG. 3) of notches that communicate with the inside and outside of the chamber 63, i.e., the chamber 63 and the first chamber 2A. In other words, the chamber 63 is always in communication with the first chamber 2A via the plurality of notches 62 formed in the protruding portion 61. The plurality of notches 62 are arranged at equal intervals (at 90-degree intervals in the first embodiment) in the circumferential direction of the disk 43.

[0023] Next, the flow of hydraulic oil in the first embodiment will be described. During the compression stroke, the pressure in the second chamber 2B increases as the piston rod 10 (piston 3) moves, and hydraulic oil flows from the second chamber 2B (one chamber) to the first chamber 2A (the other chamber) via the compression-side passage 6. At this time, the valve element 33 of the compression-side damping force mechanism 31 opens and closes depending on the moving speed of the piston 3 (hereinafter referred to as "piston speed").

[0024] When the piston speed is extremely low, the pressure in the compression passage 6 (second chamber 2B) does not reach the valve-opening pressure of the valve element 33, so hydraulic oil flows from the second chamber 2B to the first chamber 2A via the compression passage 6 and the notch 44 (orifice) formed in the disc 42. This causes the compression damping force mechanism 31 to generate a damping force with orifice characteristics. When the piston speed increases and the pressure in the compression passage 6 reaches the valve-opening pressure of the valve element 33, the compression damping force mechanism 31 generates a damping force with valve characteristics that correspond to the opening of the valve element 33.

[0025] That is, as the piston speed increases, the first valve body 41 (first valve member) is biased in the valve-opening direction (the "upward direction" in FIG. 2 ) by the pressure in the compression-side passage 6 and the biasing force of the elastic member 38 (second biasing member). The first valve body 41, which receives the biasing force in the valve-opening direction, compresses the elastic member 37 (first biasing member) in the axial direction and biases (pressures) the outer periphery of the second valve body 51 (second valve member) in the valve-opening direction (the "upward direction" in FIG. 2 ) via the protrusion 61 (chamber forming portion), thereby opening the second valve body 51 (elastic deformation), and moves in the direction opposite the piston 3 (the "upward direction" in FIG. 2 ). As a result, the first valve body 41 lifts off the seat portion 32, and the valve element 33 is opened.

[0026] On the other hand, during the extension stroke, the pressure in the first chamber 2A increases as the piston rod 10 (piston 3) moves, and hydraulic oil flows from the first chamber 2A to the second chamber 2B via the extension-side passage 5. At this time, the valve element 25 of the extension-side damping force mechanism 21 opens and closes depending on the piston speed.

[0027] When the piston speed is extremely low, the pressure in the extension-side passage 5 (first chamber 2A) does not reach the valve-opening pressure of the valve element 25, so hydraulic oil flows from the first chamber 2A to the second chamber 2B via the extension-side passage 5 and the notch 26 (orifice) formed in the valve element 25 (disc). This causes the extension-side damping force mechanism 21 to generate a damping force with orifice characteristics. When the piston speed increases and the pressure in the extension-side passage 5 reaches the valve-opening pressure of the valve element 25, the extension-side damping force mechanism 21 generates a damping force with valve characteristics according to the opening of the valve element 25.

[0028] In a conventional shock absorber, for example, when the valve characteristics of the compression damping force mechanism are set low, it is necessary to reduce the number of stacked discs that make up the valve body of the compression damping force mechanism. In this case, the piston speed increases during the extension stroke, increasing the pressure (back pressure) in the first chamber, which could damage the valve body of the compression damping force mechanism.

[0029] In contrast, in the first embodiment, the compression side damping force mechanism 31 includes a first valve body 41 (first valve member) that is capable of contacting the seat portion 32 and is movable in the axial direction, a second valve body 51 (second valve member) that is located farther away from the piston 3 than the first valve body 41 and has lower rigidity than the first valve body 41, an annular protrusion 61 (chamber forming portion) that is located on the outer peripheral edge of the first valve body 41 and has an apex that abuts against the second valve body 51, an annular chamber 63 formed between the first valve body 41 and the second valve body 51, and a notch 62 (chamber passage) that is formed in the protrusion 61 and that connects the inside and outside of the chamber 63 (first chamber 2A).

[0030] According to the first embodiment, chamber 63 and first chamber 2A are constantly in communication with each other through notch 62 formed in protrusion 61, so the pressure inside chamber 63 (back pressure of second valve body 51) and the pressure in first chamber 2A are always kept equal. Furthermore, because the rigidity of first valve body 41 (first valve member) is set to be sufficiently higher than the rigidity of second valve body 51 (second valve member), even if the pressure in the first chamber increases with an increase in piston speed during the extension stroke, it is possible to prevent second valve body 51 from being damaged by being pushed toward piston 3 due to the pressure in the first chamber (back pressure). This makes it possible to achieve both low valve characteristics and high valve durability.

[0031] In the first embodiment, the inner peripheral portion 46 of the first valve body 41 (first valve member) is clamped (biased) in the axial direction by the elastic member 37 (first biasing member) and the elastic member 38 (second biasing member), so the first valve body 41 can be moved in the axial direction to open the valve body 33 while ensuring the rigidity of the first valve body 41. Furthermore, since sealing members such as O-rings are used as the elastic members 37 and 38, it is possible to prevent pressure from leaking from the gap between the inner peripheral portion 46 of the first valve body 41 and the collar 34, which would cause the damping force characteristics to become unstable.

[0032] The embodiment is not limited to the above-described form, and can be configured as follows, for example. In the first embodiment, the chamber 63 is formed by forming the protruding portion 61 (chamber forming portion) on the outer peripheral edge portion of the first valve body 41 (first valve member), but the chamber 63 may also be formed by forming the protruding portion 61 (chamber forming portion) by causing the outer peripheral edge portion of the second valve body 51 (second valve member) to protrude toward the piston 3 side (the "downward" side in FIG. 2). In this case, the abutting portion 57 is formed on the outer peripheral edge portion of the first valve body 41. Furthermore, in the first embodiment, a chamber 63 is formed by forming a protrusion 61 (chamber forming portion) on the outer peripheral edge of the first valve body 41 (first valve member), and a notch 62 (chamber passage) is formed in the protrusion 61 to connect the inside and outside of the chamber 62 (first chamber 2A). However, the inside and outside of the chamber 62 may also be connected by arranging arc-shaped members at intervals in the circumferential direction on one side of the first valve body 41 (the side opposite to the piston 3 side). Alternatively, instead of forming the protrusion 61 on the first valve body 41 or the second valve body 51, the chamber 63 may be formed by interposing an annular member (chamber forming portion) separate from the first valve body 41 and the second valve body 51, and a notch 62 (chamber passage) may be formed in the annular member to connect the inside and outside of the annular member (first chamber 2A). Furthermore, the configuration including the chamber 63 of the compression side damping force mechanism 31 described above can be applied to the extension side damping force mechanism 21.

[0033] (Second embodiment) Next, a second embodiment will be described with reference to FIGS. The same names and symbols are used for parts common to the first embodiment, and duplicated explanations will be omitted. In the first embodiment, a notch 62 (chamber passage) is formed in a protrusion 61 (chamber forming portion) formed on the outer peripheral edge of the first valve body 41 (first valve member), and the inside and outside of the chamber 62 (first chamber 2A) are configured to communicate with each other.

[0034] In contrast, in the second embodiment, no notch 62 (chamber passage) is formed in the protrusion 61 (chamber forming portion), and multiple (five in the second embodiment) holes 58 (chamber passages) that connect the inside and outside of the chamber 62 (first chamber 2A) are formed radially inward of the abutment portion 57 in the second valve body 51 (second valve member).

[0035] According to the second embodiment, it is possible to obtain the same effects as those of the first embodiment described above. Furthermore, for example, as shown in FIG. 7, by changing the shape or number of holes 58 (chamber passages), the rigidity of the second valve body 51 (second valve member), and therefore the valve opening pressure (initial load) of the valve body 33 of the compression side damping force mechanism 31, can be adjusted. [Explanation of symbols]

[0036] 1 shock absorber, 2 cylinder, 2A first chamber, 2B second chamber, 3 piston, 5 extension side passage, 6 compression side passage, 10 piston rod, 11 first end, 31 compression side damping force mechanism, 41 first valve body (first valve member), 51 second valve body (second valve member), 62 notch (chamber passage), 63 chamber

Claims

1. a cylinder in which a working fluid is sealed; a piston provided in the cylinder and dividing the interior of the cylinder into two chambers; a piston rod having a first end connected to the piston and a second end extending from inside the cylinder to the outside; a passage provided in the piston and communicating the two chambers; a damping force mechanism that is provided in the passage and opens when the working fluid moves from one of the two chambers to the other; Equipped with The damping force mechanism includes: a first valve member that is disposed so as to be able to come into contact with the piston and that is movable in the axial direction; a second valve member that is disposed farther from the piston than the first valve member and has lower rigidity than the first valve member; a chamber formed between the first valve member and the second valve member; a chamber passage communicating the inside and outside of the chamber; A buffer having

2. 2. The shock absorber according to claim 1, The chamber passage is formed by a chamber forming portion provided between the first valve member and the second valve member.

3. 2. The shock absorber according to claim 1, a shock absorber having a first biasing member provided between the first valve member and the second valve member, and biasing the first valve member and the second valve member in the axial direction;

4. 4. The shock absorber according to claim 3, a shock absorber having a second biasing member provided between the first valve member and the piston, and biasing the first valve member in the axial direction;

5. 2. The shock absorber according to claim 1, the chamber forming portion is a protrusion that protrudes in the axial direction from the first valve member or the second valve member, The chamber passage is a notch formed in the protrusion.

6. 2. The shock absorber according to claim 1, the second valve member has an abutment portion formed radially outward of the second valve member and capable of abutting against the first valve member, The chamber passage is a hole provided in the second valve member and formed radially inward of the second valve member relative to the abutment portion.

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