Shock absorber

Abstract

In the present invention, a shock absorber (10) includes an outer tube (20), an inner tube (30) fitted to the outer tube (20), a sliding member (40) provided on one end (21) of the outer tube (20), a surrounding member (70) capable of moving relative to the inner tube (30), and a damping force generation unit (100) formed on an outer peripheral surface (41) of the sliding member (40) along an axial direction (Rs). The sliding member (40) has a rod (50) that extends from the one end (21) of the outer tube (20) to the inside (34) of the inner tube (30), and a first partition wall (60) that is provided to the rod (50) and is in sliding contact with the inner peripheral surface (35) of the inner tube (30). The surrounding member (70) surrounds the outer peripheral surface (41) of the sliding member (40). The damping force generation unit (100) can generate damping force between the damping force generation unit (100) and the inner peripheral surface (71) of the surrounding member (70).

Description

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[0001] The present invention relates to an improved technique for shock absorbers.

[0002] Shock absorbers with a telescopic outer tube and inner tube are used in suspension systems mounted on various vehicles, such as motorcycles, three-wheeled vehicles, and four-wheeled vehicles. For example, some front forks use a so-called cartridge-type shock absorber in which an inner tube is provided inside an outer tube (the tube on the axle side), a piston is provided slidably within the inner tube, and a rod connected to the piston is provided on the outer tube. Such a shock absorber is known, for example, from Patent Document 1.

[0003] The shock absorber known from Patent Document 1 has an inner tube on the vehicle body side slidably inserted into an outer tube on the wheel side, a hollow pipe extending from the bottom of the outer tube into the inner tube, and a partition wall at the tip of the hollow pipe separating the inner tube into an upper oil chamber and a lower oil chamber. The hollow pipe has a flow path consisting of small holes that penetrate the hollow pipe in the radial direction. This flow path generates flow resistance when oil passes between the oil reservoir chamber inside the hollow pipe and the oil chamber outside the hollow pipe. The shock absorber generates a damping force due to this flow resistance.

[0004] JP 2013-177954 A

[0005] In the shock absorber known from Patent Document 1, if the expansion / contraction speed of the inner tube is constant, the flow resistance is constant regardless of the amount of expansion / contraction of the inner tube. Therefore, the damping force caused by the flow resistance is also constant. Depending on the application of the shock absorber, such as when it is installed in a vehicle, it is preferable to be able to finely adjust the damping force according to the amount of expansion / contraction of the inner tube.

[0006] An object of the present invention is to provide a shock absorber technology that allows the damping force to be finely adjusted according to the amount of expansion and contraction of the inner tube.

[0007] As a result of extensive research, the inventors have noticed that the flow path resistance generated by the flow of hydraulic fluid does not have to be limited to a flow path consisting of holes penetrating in the radial direction. They have also found that the flow path resistance can be set even if the direction in which the hydraulic fluid flows is changed. The present invention was completed based on this finding.

[0008] According to the present disclosure, there is provided a shock absorber including: a cylindrical outer tube; a cylindrical inner tube, at least a portion of which is fitted into the inside of the outer tube so as to be movable relative to the axial direction of the outer tube; a sliding member having a rod extending from one end of the outer tube into the inside of the inner tube; a first partition portion provided on the rod and in sliding contact with the inner surface of the inner tube to divide the inside of the inner tube into a first chamber and a second chamber; an enclosing member that is a member movable together with the inner tube relative to the outer tube and surrounds at least a portion of the outer surface of the sliding member in the axial direction; and a damping force generating portion formed on the outer surface of the sliding member along the axial direction and capable of generating a damping force between the outer surface of the enclosing member and the sliding member.

[0009] The present disclosure can provide a shock absorber technology that allows for precise adjustment of the damping force generated in accordance with the amount of expansion and contraction of the inner tube.

[0010] FIG. 2A is a cross-sectional view of the shock absorber according to the first embodiment. FIG. 2A is an enlarged cross-sectional view of the damping force generating portion and its surroundings shown in FIG. 1, and FIG. 2B is a cross-sectional view taken along line 2B-2B in FIG. 2A. FIG. 3A is an enlarged view of portion 3A in FIG. 2B, and FIG. 3B is a cross-sectional view taken along line 3B-3B in FIG. 3A. FIG. 4A is an enlarged view of portion 4A in FIG. 2B, and FIG. 4B is a cross-sectional view taken along line 4B-4B in FIG. 4A. FIG. 5A is a perspective view of the sliding member shown in FIG. 2A, FIG. 5B is an enlarged view of portion 5B in FIG. 5A, FIG. 5C is a view taken along arrow 5C in FIG. 5B, and FIG. 5D is a cross-sectional view taken along line 5D-5D in FIG. 5B. FIG. 6A is an explanatory diagram showing the flow of hydraulic fluid when the shock absorber shown in FIG. 2B is in the extension stroke, and FIG. 6B is an enlarged view of portion 6B in FIG. 6A. Fig. 7A is an explanatory diagram showing the flow of hydraulic fluid during the compression stroke of the shock absorber shown in Fig. 2B, and Fig. 7B is an enlarged view of portion 7B of Fig. 7A. Fig. 9A is an extension damping force characteristic diagram showing the extension damping force characteristic with respect to the extension speed of the shock absorber shown in Fig. 2A, and Fig. 9B is an extension damping force characteristic diagram showing the compression damping force characteristic with respect to the compression speed of the shock absorber shown in Fig. 2A. Figs. 10A to 10D are diagrams showing modified examples of the second groove shown in Figs. 5A to 5D. Figs. 11A and 11B are perspective views of a configuration having a recess on the end surface of the first partition wall shown in Fig. 5B. Fig. 12A is a side view of a damping force generating portion of a shock absorber according to Example 2, Fig. 12B is a cross-sectional view taken along line 12B-12B of Fig. 12A, and Fig. 12C is a cross-sectional view taken along line 12C-12C of Fig. 12A. Fig. 13A is a side view of a damping force generating portion of a shock absorber according to Example 3, Fig. 13B is a cross-sectional view taken along line 13B-13B of Fig. 13A, and Fig. 13C is a cross-sectional view taken along line 13C-13C of Fig. 13A. Fig. 14A is a side view of a damping force generating portion of a shock absorber according to Example 4, Fig. 14B is a cross-sectional view taken along line 14B-14B of Fig. 14A, Fig. 14C is a cross-sectional view taken along line 14C-14C of Fig. 14A, and Fig. 14D is a cross-sectional view taken along line 14D-14D of Fig. 14A. Figure 15A is a first example diagram in which the position of the second groove matches the position of the first groove in the damping force generating portion of the shock absorber according to Example 5, Figure 15B is a second example diagram in which the position of the second groove is displaced by 45° relative to the first groove shown in Figure 15A, and Figure 15C is a third example diagram in which the position of the second groove is displaced by 90° relative to the first groove shown in Figure 15A.

[0011] An embodiment of the present invention will be described below with reference to the accompanying drawings. Note that the embodiment shown in the accompanying drawings is an example of the present invention, and the present invention is not limited to this embodiment. In the description, "up" and "down" refer to the state in which the shock absorber is mounted on a saddle-ride type vehicle. In addition, "Up" in the drawings refers to the top, and "Dn" refers to the bottom.

[0012] First Embodiment A shock absorber 10 according to a first embodiment will be described with reference to FIGS. 1 to 11. FIG.

[0013] 1, the shock absorber 10 is used in, for example, a motorcycle, which is a type of saddle-ride vehicle (not shown) on which a rider straddles. Hereinafter, a motorcycle may be referred to as a "saddle-ride vehicle."

[0014] The shock absorber 10 is used in, for example, the front fork of a saddle-ride type vehicle, but the shock absorber 10 can also be used in a rear cushion, and can also be employed in an automobile.

[0015] This shock absorber 10 includes a cylindrical outer tube 20 (axle-side tube 20) on the axle (not shown) side, and a cylindrical inner tube 30 (vehicle-body-side tube 30) connected to a bracket (not shown) on the vehicle body side. At least a portion of the inner tube 30 is fitted inside the outer tube 20 so as to be relatively movable in the axial direction Rs of the outer tube 20, and is located on the center line CL of the outer tube 20.

[0016] In the first embodiment, the shock absorber 10 will be described as having an upright configuration in which the vehicle body side tube 30 (inner tube 30) is moved forward and backward relative to the axle side tube 20 (outer tube 20). However, the shock absorber 10 also includes an inverted configuration in which the axle side tube 20 is moved forward and backward relative to the vehicle body side tube 30.

[0017] The outer tube 20 is a so-called bottomed cylindrical member having one end 21 (first end 21) on the axle (not shown) side that is closed and the other end 22 (second end 22) that can receive the inner tube 30 that is open. More specifically, the one end 21 of the outer tube 20 is closed by a closing portion 23 (bottom plate 23) and has an axle-side bracket 24. The other end 22 of the outer tube 20 has a portion where the inner tube 30 is inserted sealed by a seal member 25.

[0018] The inner tube 30 is a so-called bottomed cylindrical member in which one end 31 (first end 31) on the vehicle body side (not shown) is closed and the other end 32 (second end 32) is open. More specifically, the one end 31 of the inner tube 30 is closed by a cap bolt 33.

[0019] 1 and 2A, the shock absorber 10 further includes a sliding member 40 extending from one end 21 of the outer tube 20 into the interior 34 of the inner tube 30. This sliding member 40 has a rod 50 extending from one end 21 of the outer tube 20 into the interior 34 of the inner tube 30, and a first partition wall 60 provided at a tip end 52 of this rod 50. The diameter of the first partition wall 60 is larger than the diameter of the rod 50. The center line of the sliding member 40 coincides with the center line CL of the outer tube 20. Hereinafter, the center line CL of the outer tube 20 may be referred to as the "center line CL of the sliding member 40" as appropriate.

[0020] A base end surface 51 of the rod 50 opposite the first partition wall portion 60 is fixed to the closure portion 23 of one end 21 of the outer tube 20 by a screw member 53. Specifically, the base end surface 51 of the rod 50 has a female thread 54 (fastening portion 54) on the center line CL of the sliding member 40. The screw member 53 (headed bolt 53) can be inserted through the closure portion 23 and screwed into the female thread 54 to fasten the base end surface 51 of the rod 50 to the closure portion 23.

[0021] Here, the rod 50 may be referred to as the "pillar portion 50" or the "column 50." The base end surface 51 of the rod 50 may be referred to as the "first end surface 51." The tip portion 52 (tip surface 52) of the rod 50 is the surface of the rod 50 opposite the base end surface 51, and may be referred to as the "second end surface 52."

[0022] The first partition wall 60 (first piston 60) is in sliding contact with the inner circumferential surface 35 of the inner tube 30, dividing the interior 34 of the inner tube 30 into a first chamber 36 and a second chamber 37. The first chamber 36 is the space between the closed first end 31 of the inner tube 30 and the first partition wall 60, and constitutes an air chamber and a liquid reservoir chamber. The second chamber 37 is the space inside the inner tube 30 on the opposite side from the first partition wall 60, and constitutes a liquid chamber. An annular groove 62 (ring fitting groove 62) is formed in the outer circumferential surface 61 of the first partition wall 60. A piston ring 63 is fitted into this ring fitting groove 62, and is in sliding contact with the inner circumferential surface 35 of the inner tube 30. The outer circumferential surface 55 of the rod 50 and the outer circumferential surface 61 of the first partition wall 60 are sometimes collectively referred to as the outer circumferential surface 41 of the sliding member 40.

[0023] The inner tube 30 has a surrounding member 70 disposed at the second end 32 (open end 32). The surrounding member 70 is a member that is movable in the axial direction Rs together with the inner tube 30 relative to the outer tube 20, and is fixed to the inner circumferential surface 35 of the inner tube 30. The surrounding member 70 surrounds at least a portion of the outer circumferential surface 41 of the sliding member 40 in the axial direction Rs (i.e., the outer circumferential surface 55 of the rod 50). In this way, the surrounding member 70 is movable in the axial direction Rs relative to the outer circumferential surface 55 of the rod 50.

[0024] Furthermore, by being positioned closer to the second end 32 (open end 32) of the inner tube 30 than the first partition 60, the surrounding member 70 constitutes a second partition that separates the inside and outside of the inner tube 30 in the axial direction Rs. The surrounding member 70 may be referred to as the "second partition 70" or the "second piston 70" as appropriate.

[0025] In this way, the second chamber 37 is defined by the first partition wall 60 and the second partition wall 70 within the interior 34 of the inner tube 30. The space 38 defined by the closure portion 23 and the second partition wall 70 (enclosing member 70) within the outer tube 20 is referred to as the "third chamber 38." This third chamber 38 constitutes a liquid chamber. The second partition wall 70 defines the second chamber 37 and the third chamber 38.

[0026] In the first chamber 36, a compression coil spring 81 is interposed between the cap bolt 33 and the first partition wall portion 60. In other words, the compression coil spring 81 is located in the first chamber 36 and biases the outer tube 20 and the inner tube 30 in directions separating them from each other. In the second chamber 37, a rebound spring 82 is interposed between the first partition wall portion 60 and the surrounding member 70. This rebound spring 82 is made of a compression coil spring, and during the extension stroke of the shock absorber 10, it restricts the maximum extension stroke at the time of maximum extension, which is the stroke end of the extension stroke.

[0027] Next, the sliding member 40 will be described in detail. As shown in Figures 2A and 2B, the sliding member 40 is a solid resin integrally molded product, and is molded by, for example, injection molding. The resin material used may be, for example, a glass fiber-reinforced resin.

[0028] 3A, 3B, 4A, and 4B, the rod 50 and the first partition wall 60 are configured to have a perfectly circular cross section. The rod 50 and the first partition wall 60 are concentric with each other and coincide with the center line CL of the outer tube 20 and the inner tube 30. The rod 50 is configured in the shape of a straight round bar (cylindrical column). The first partition wall 60 is continuous with the tip end 52 of the rod 50. The diameter of the first partition wall 60 is larger than the diameter of the rod 50.

[0029] Furthermore, the sliding member 40 has a damping force generating portion 100 formed along the axial direction Rs on the outer peripheral surface 41 of the sliding member 40. The damping force generating portion 100 is capable of generating a damping force between itself and the inner peripheral surface 71 of the surrounding member 70.

[0030] The damping force generating portion 100 is configured with at least one (e.g., multiple) communication portion 101 that communicates with at least one of the first partition portion 60 and the second partition portion 70 so as to straddle the axial direction Rs. For example, the communication portion 101 communicates with both the first partition portion 60 and the second partition portion 70 so as to straddle the axial direction Rs. In other words, the communication portion 101 penetrates both the first and second partition portions 60, 70 in the axial direction Rs. The position and range of the communication portion 101 with respect to the rod 50 are set so that the communication portion 101 penetrates the second partition portion 70 in the axial direction Rs even when the shock absorber 10 expands and contracts to the maximum stroke from the stroke end of the extension stroke to the stroke end of the compression stroke.

[0031] Here, an example is given in which the damping force generating unit 100 is configured with two communication portions 101. The two communication portions 101 are configured by two first communication portions 110 formed in the first partition wall portion 60 and two second communication portions 120 formed in the rod 50. Each of the first communication portions 110 penetrates the first partition wall portion 60 in the axial direction Rs, thereby connecting the first chamber 36 and the second chamber 37. Each of the second communication portions 120 begins at the second end face 52 (tip surface 52) of the rod 50 and continues to an arbitrary end on the first end face 51 side as an end point 120a, thereby connecting the second chamber 37 and the third chamber 38. The end point 120a is set at an arbitrary position on or near the first end face 51. Each of the second communication portions 120, 120 formed in the rod 50 is capable of generating a damping force due to flow path resistance when hydraulic fluid such as oil passes through.

[0032] 5A to 5D , in a cross section perpendicular to the center line CL of the sliding member 40, the first communicating portions 110 and the second communicating portions 120 are positioned in the same direction. For example, in a cross section perpendicular to the center line CL of the sliding member 40, assume orientations of 0°, 90°, 180°, and 270° relative to the center line CL. The first communicating portions 110 are positioned at 0° and 180°. The second communicating portions 120 are also positioned at the same angles of 0° and 180° as the first communicating portions 110. Therefore, when the sliding member 40 is viewed in a direction perpendicular to the center line CL, the first communicating portions 110 and the second communicating portions 120 are formed in a straight line with respect to the center line CL of the sliding member 40.

[0033] 5A to 5D, the first communicating portion 110 is configured by a portion 111 in which a distance a2 from the center line CL is shorter than a distance a1 from the center line CL to the outer peripheral surface 61 of the first partition wall portion 60 in a cross section perpendicular to the center line CL of the sliding member 40. The second communicating portion 120 is configured by a portion 121 in which a distance b2 from the center line CL is shorter than a distance b1 from the center line CL to the outer peripheral surface 55 of the rod 50 in a cross section perpendicular to the center line CL of the sliding member 40.

[0034] More specifically, the first communication portion 110 is configured by a groove (recess) formed in the outer peripheral surface 61 of the first partition portion 60. The second communication portion 120 is configured by a groove (recess) formed in the outer peripheral surface 55 of the rod 50. In other words, the communication portion 101 (the first communication portion 110 and the second communication portion 120) is configured by a groove formed in the outer peripheral surface 41 of the sliding member 40. As appropriate, the first communication portion 110 may be referred to as the "first groove 110" and the second communication portion 120 as the "second groove 120." The first groove 110 is closed by the inner peripheral surface 35 of the inner tube 30. The second groove 120 is closed by the inner peripheral surface 71 of the surrounding member 70. In a cross section perpendicular to the center line CL of the sliding member 40, the first groove 110 and the second groove 120 may have any shape, such as an arc shape. In addition, in a cross section perpendicular to the center line CL of the sliding member 40, the cross-sectional area (first cross-sectional area) of the first groove 110 is A1, and the cross-sectional area (second cross-sectional area) of the second groove 120 is A2.

[0035] Next, the operation of the shock absorber 10 of Example 1 will be described. As shown in Figure 1, the shock absorber 10 absorbs and mitigates an external impact force by using the elastic force of the compression coil spring 81 and the air spring action of the first chamber 36 (air chamber 36), and damps the vibration of the compression coil spring 81 that accompanies the absorption of this impact force by the following damping action.

[0036] 6A and 6B show the flow of hydraulic fluid when the shock absorber 10 is in the extension stroke. During the extension stroke, as the inner tube 30 extends relative to the outer tube 20 (in the direction of arrow Rt), the hydraulic pressure in the second chamber 37 increases. The hydraulic fluid in the second chamber 37 flows through the second communication portions 120 to the third chamber 38. A damping force (second extension damping force) is generated due to the flow resistance encountered when the hydraulic fluid passes through the second communication portions 120. The size of the second cross-sectional area A2 of the second communication portion 120 affects the second extension damping force. Furthermore, the hydraulic fluid in the second chamber 37 flows through the first communication portions 110 to the first chamber 36 in accordance with the pressure difference between the second chamber 37 and the first chamber 36. A damping force (first extension damping force) is generated due to flow resistance when the hydraulic fluid passes through each of the first communication portions 110, 110. The size of the first cross-sectional area A1 of the first communication portion 110 affects the first extension damping force.

[0037] The sum of the first extension damping force and the second extension damping force is called the total extension damping force. The pressure difference between the low-pressure first chamber 36 and the second chamber 37, which form the liquid reservoir chamber, is greater than the pressure difference between the third chamber 38 and the second chamber 37, which form the liquid chamber. Therefore, the size of the first cross-sectional area A1 has a greater effect on the total extension damping force than the size of the second cross-sectional area A2. By setting the size of the second cross-sectional area A2 to be small, the total extension damping force can be set to be large.

[0038] 7A and 7B show the flow of hydraulic fluid when the shock absorber 10 is in the compression stroke. During the compression stroke, as the inner tube 30 contracts relative to the outer tube 20 (in the direction of arrow Rc), the hydraulic pressure in the third chamber 38 increases. The hydraulic fluid in the third chamber 38 flows through the second communication portions 120 and into the second chamber 37. A damping force (first compression damping force) is generated due to the flow resistance encountered when the hydraulic fluid passes through the second communication portions 120. The excess hydraulic fluid that has flowed into the second chamber 37 flows through the first communication portions 110 and into the first chamber 36. A damping force (second compression damping force) is generated due to the flow resistance encountered when the hydraulic fluid passes through the first communication portions 110. The sum of the first compression damping force and the second compression damping force is referred to as the total compression damping force.

[0039] Next, with reference to FIG. 8 , differences in damping force due to the difference between the first cross-sectional area A1 of the first groove 110 and the second cross-sectional area A2 of the second groove 120 will be described. FIG. 8 shows five models M1 to M5 that represent the differences in damping force Ft due to the difference between the first cross-sectional area A1 and the second cross-sectional area A2, based on a fluid flow analysis performed when the shock absorber 10 is in the extension stroke. Here, the second grooves 120 of the first model M1, the second model M2, and the fifth model M5 have the same groove width, groove depth, and second cross-sectional area A2. The second grooves 120 of the third model M3 and the fourth model M4 have half the groove width, the same groove depth, and half the second cross-sectional area A2 of the second groove 120 of the first model M1.

[0040] The first model M1 shows the damping force generated when the groove width of the first groove 110 is the same as that of the second groove 120, and the first cross-sectional area A1 is set to twice the second cross-sectional area A2 (A1 = A2 × 2). The first model M1 has the smallest damping force. The second model M2 shows the damping force generated when the first cross-sectional area A1 is set to be slightly smaller than the second cross-sectional area A2. The damping force of the second model M2 is slightly larger than that of the first model M1. The third model M3 shows the damping force generated when the first cross-sectional area A1 is set to be the same as that of the second cross-sectional area A2 (A1 = A2). The damping force of the third model M3 is slightly larger than that of the second model M2. The fourth model M4 has the same size and first cross-sectional area A1 of the first groove 110 as those of the second model M2. The damping force of this fourth model M4 is slightly greater than the damping force of the third model M3. The fifth model M5 shows the damping force generated when the first cross-sectional area A1 is set significantly smaller than the second cross-sectional area A2. The damping force of this fifth model M5 increases sharply compared to the other models M1 to M4. As a result of the above, it can be seen that in order to increase the damping force when the shock absorber 10 is in the extension stroke, it is effective to set the first cross-sectional area A1 significantly smaller than the second cross-sectional area A2.

[0041] 9A and 9B, a description will be given of the difference in damping force due to the difference between the first cross-sectional area A1 of the first groove 110 and the second cross-sectional area A2 of the second groove 120. Figures 9A and 9B show the results of a flow analysis of the difference in damping force due to the difference in cross-sectional areas A1 and A2, based on the results of the flow analysis in Figure 8 above, and taking into account the expansion / contraction speed of the shock absorber 10.

[0042] 9A is an extension damping force characteristic diagram showing the extension damping force Ft versus extension speed Vt, with the horizontal axis representing the extension speed Vt of the shock absorber 10 and the vertical axis representing the extension damping force Ft of the shock absorber 10. Here, Q1 is the first extension characteristic line, which represents the extension damping force Ft during extension for the first model M1 of FIG. 8 (i.e., the relationship A1 = A2 × 2). Q2 is the second extension characteristic line, which represents the extension damping force Ft during extension for the third model M3 of FIG. 8 (i.e., the relationship A1 = A2). Q3 is the third extension characteristic line, which represents the extension damping force Ft during extension for the fifth model M5 of FIG. 8 (i.e., the relationship A1 = A2 × 1 / 3). It can be seen from FIG. 9A that the extension damping force Ft is small for the characteristics of the first extension characteristic line Q1 and the second extension characteristic line Q2, regardless of the extension speed Vt. Furthermore, in the characteristics of the third extension characteristic line Q3, it can be seen that as the extension speed Vt increases, the extension damping force Ft increases rapidly.

[0043] FIG. 9B is a compression damping force characteristic diagram showing the characteristics of the compression damping force Fc versus the compression speed Vc of the shock absorber 10, with the horizontal axis representing the compression speed Vc of the shock absorber 10 and the vertical axis representing the compression damping force Fc of the shock absorber 10. Here, Q11 is the first compression characteristic line, which shows the compression damping force Fc during compression in the case of the first model M1 of FIG. 8 (i.e., the relationship A1 = A2 × 2). Q12 is the second compression characteristic line, which shows the compression damping force Fc during compression in the case of the third model M3 of FIG. 8 (i.e., the relationship A1 = A2). Q13 is the third compression characteristic line, which shows the compression damping force Fc during compression in the case of the fifth model M5 of FIG. 8 (i.e., the relationship A1 = A2 × 1 / 3). FIG. 9B shows that the compression damping force Fc is small for all of the compression characteristic lines Q11 to Q13, regardless of the compression speed Vc.

[0044] As a result of the above, it is found that setting the first cross-sectional area A1 to be significantly smaller than the second cross-sectional area A2 is effective in increasing the damping force during the extension stroke of the shock absorber 10.

[0045] The shapes and sizes of the first grooves 110 and the second grooves 120 are not limited to those shown in FIGS. 5A to 5D. For example, other examples of the second grooves 120 are shown in FIGS. 10A to 10D. The two second grooves 120 shown in FIG. 10A have angular cross sections. The two second grooves 120 shown in FIG. 10B have V-shaped cross sections, with one second groove 120 being more widely spaced than the other. The two second grooves 120 shown in FIG. 10C have T-shaped or dovetail cross sections. Of the two second grooves 120 shown in FIG. 10D, one second groove 120 has an angular cross section and the other second groove 120 has a flat surface. The first grooves 110 are similar to the second grooves 120.

[0046] 11A and 11B, the first partition 60 of the sliding member 40 preferably has a recess 65 into which a jig Jg (tool Jg) can be inserted, on an end face 64 opposite the rod 50. The first partition 60 shown in Fig. 11A has a hexagonal recess 65 on the end face 64, and has chamfered portions 66 on the entire edge of the end face 64 and on the edges of each of the first grooves 110, 110. The first partition 60 shown in Fig. 11B has a dodecagonal recess 65 on the end face 64, and has chamfered portions 66 on the entire edge of the end face 64.

[0047] When fastening the base end surface 51 of the rod 50 to the closure portion 23 with the screw member 53, the jig Jg is hooked onto the recess 65 and pressed down. This prevents the sliding member 40 from rotating together with the screw member 53. Furthermore, since the first partition portion 60 has a chamfered portion 66 on the edge of the end face 64, the inner circumferential surface 35 of the inner tube 30 can slide smoothly against the first partition portion 60.

[0048] Second Embodiment A shock absorber 200 according to a second embodiment will be described with reference to FIGS. 12A to 12C.

[0049] Figures 12A to 12C are cross-sectional views illustrating a shock absorber 200, and correspond to Figures 5A to 5D. The shock absorber 200 of the second embodiment is characterized in that the second communication portions 120, 120 of the first embodiment shown in Figures 5A to 5D are replaced with second communication portions 220, 220 shown in Figures 12A to 12C. The other basic configuration is common to the shock absorber 10 of the first embodiment. The same reference numerals are used for parts common to the shock absorber 10 of the first embodiment, and detailed descriptions thereof will be omitted.

[0050] The second cross-sectional area A2 of the second communication portions 220, 220 is set to gradually increase from the tip end surface 52 (start point 52) ​​of the rod 50 to the end point 120a toward the base end surface 51. The size of the first cross-sectional area A1 of the first communication portion 110 is the same as in Example 1. Other functions and effects of the shock absorber 200 of Example 2 are the same as those of the shock absorber 10 of Example 1 described above.

[0051] Third Embodiment A shock absorber 300 according to a third embodiment will be described with reference to FIGS. 13A to 13C.

[0052] Figures 13A to 13C are cross-sectional views illustrating a shock absorber 300, and correspond to Figures 5A to 5D. The shock absorber 300 of the third embodiment is characterized in that the second communication portions 120, 120 of the first embodiment shown in Figures 5A to 5D are replaced with second communication portions 320, 320 shown in Figures 13A to 13C. The other basic configuration is common to the shock absorber 10 of the first embodiment. The same reference numerals are used for parts common to the shock absorber 10 of the first embodiment, and detailed description thereof will be omitted.

[0053] The size of the second cross-sectional area A2 of the second communicating portions 320, 320 is set so as to gradually increase from the tip surface 52 (start point 52) ​​of the rod 50 to an arbitrary intermediate position 120b toward the base end surface 51, and to gradually decrease from the intermediate position 120b toward the end point 120a. The size of the first cross-sectional area A1 of the first communicating portion 110 is the same as in Example 1. Other functions and effects of the shock absorber 300 of Example 3 are the same as those of the shock absorber 10 of Example 1 described above.

[0054] Fourth Embodiment A shock absorber 400 according to a fourth embodiment will be described with reference to FIGS. 14A to 14D.

[0055] Figures 14A to 14D are cross-sectional views illustrating a shock absorber 400, and correspond to Figures 5A to 5D. The shock absorber 400 of Example 4 is characterized in that the plurality of second communication portions 120 of Example 1 shown in Figures 5A to 5D are replaced with a plurality of second communication portions 420A to 420C shown in Figures 14A to 14D. The size of the first cross-sectional area A1 of the first communication portion 110 is the same as in Example 1. The rest of the basic configuration is common to the shock absorber 10 of Example 1. The same reference numerals are used for parts common to the shock absorber 10 of Example 1, and detailed descriptions thereof will be omitted.

[0056] In Example 4, the number of second communication portions 420A-420C is, for example, three, and all extend linearly from the end point 120a toward the tip surface 52 of the rod 50. The "first second communication portion 420A," which has the longest groove length, extends between the end point 120a and the tip surface 52 (start point 52) ​​of the rod 50. The "second second communication portion 420B," which has a groove length shorter than the first second communication portion 420A, extends to an arbitrary first intermediate point P1 between the end point 120a and the start point 52. The "third second communication portion 420C," which has a groove length shorter than the second second communication portion 420B, extends to an arbitrary second intermediate point P2 between the end point 120a and the start point 52. This third second communication portion 420C is the shortest.

[0057] When the rod 50 is viewed in the axial direction, these second communication portions 420A to 420C are arranged at different positions in the circumferential direction of the rod 50. For example, with the center line CL as the reference, the first second communication portion 420A is located at an orientation of 0°, the second second communication portion 420B is located at an orientation of 240°, and the third second communication portion 420C is located at an orientation of 120°.

[0058] In the range from the starting point 52 to the first intermediate point P1, the damping force of the shock absorber 400 can be adjusted only by the cross-sectional area of ​​the first second communication portion 420A. In the range from the first intermediate point P1 to the second intermediate point P2, the damping force of the shock absorber 400 can be adjusted by the cross-sectional areas of the first and second second communication portions 420A, 420B. In the range from the second intermediate point P2 to the end point 120a, the damping force of the shock absorber 400 can be adjusted by the cross-sectional areas of all of the second communication portions 420A to 420C. Other functions and effects of the shock absorber 400 of the fourth embodiment are the same as those of the shock absorber 10 of the first embodiment.

[0059] Fifth Embodiment A shock absorber 500 according to a fifth embodiment will be described with reference to FIGS. 15A to 15C.

[0060] Figures 15A to 15C are cross-sectional views illustrating a shock absorber 500, and correspond to Figures 5A to 5D. The shock absorber 500 of Example 5 is characterized by changing the circumferential arrangement of the second communication portions 120, 120 of Example 1 shown in Figures 5A to 5D. The size of the first cross-sectional area A1 of the first communication portion 110 and the size of the second cross-sectional area A2 of the second communication portion 120 are the same as in Example 1. The rest of the basic configuration is common to the shock absorber 10 of Example 1. The same reference numerals are used for parts common to the shock absorber 10 of Example 1, and detailed descriptions thereof will be omitted.

[0061] FIG. 15A shows that, when the sliding member 40 is viewed from a direction perpendicular to the center line CL, the first communicating portions 110 and the second communicating portions 120 are positioned at the same orientations of 0° and 180°, as in Example 1. FIG. 15B shows that the positions of the second communicating portions 120 are shifted by 45° in the circumferential direction relative to the first communicating portions 110. FIG. 15C shows that the positions of the second communicating portions 120 are shifted by 90° in the circumferential direction relative to the first communicating portions 110. Thus, the shock absorber 500 of Example 5 is characterized in that the positions of the second communicating portions 120 can be changed in the circumferential direction within a range from 0° to 90° relative to the first communicating portions 110. Other functions and effects of the shock absorber 500 of the fifth embodiment are the same as those of the shock absorber 10 of the first embodiment.

[0062] The shock absorbers 10, 200 to 500 described above can be summarized as follows.

[0063] Referring to FIG. 1 (FIGS. 12 to 15), according to the first to fifth embodiments, first, the shock absorber 10, 200 to 500 includes a cylindrical outer tube 20 and a cylindrical inner tube 30, at least a portion of which is fitted into the outer tube 20 so as to be relatively movable in the axial direction Rs of the outer tube 20. The shock absorber 10 further includes a rod 50 extending from one end 21 of the outer tube 20 to the interior 34 of the inner tube 30, and a sliding member 40 having a first partition portion 60 provided on the rod 50 and in sliding contact with the inner circumferential surface 35 of the inner tube 30 to divide the interior 34 of the inner tube 30 into a first chamber 36 and a second chamber 37. The shock absorber 10 further includes a surrounding member 70 that is movable together with the inner tube 30 relative to the outer tube 20 and surrounds at least a portion of the outer circumferential surface 41 of the sliding member 40 in the axial direction Rs (i.e., the outer circumferential surface 55 of the rod 50). Furthermore, the shock absorber 10 includes a damping force generating portion 100 formed on the outer peripheral surface 41 of the sliding member 40 along the axial direction Rs and capable of generating a damping force between the inner peripheral surface 71 of the surrounding member 70.

[0064] As described above, the damping force generating unit 100 is formed along the axial direction Rs relative to the outer peripheral surface 41 of the sliding member 40 and is surrounded by the surrounding member 70 together with the outer peripheral surface 41 of the sliding member 40. Even when the surrounding member 70 moves together with the inner tube 30, it continues to surround the outer peripheral surface 41 of the sliding member 40 and the damping force generating unit 100. Flow path resistance is generated when hydraulic fluid passes between the inner peripheral surface 71 of the surrounding member 70 and the damping force generating unit 100 formed on the outer peripheral surface 41 of the sliding member 40. The shock absorbers 10, 200 to 500 generate a damping force due to this flow path resistance. By appropriately setting the cross-sectional areas A1 and A2 (see FIG. 8 ) perpendicular to the axial direction Rs between the inner peripheral surface 71 of the surrounding member 70 and the damping force generating unit 100, it is possible to set an arbitrary flow path resistance. As a result, the damping force generated according to the amount of expansion and contraction of the inner tube 30 can be set in an arbitrary and detailed manner.

[0065] See Figures 2A and 2B (Figures 12 to 15). Secondly, in the shock absorbers 10, 200 to 500 preferably described above, the sliding member 40 is made of a solid material. By making the sliding member 40 of a solid material in this way, the cross-sectional area of ​​the sliding member 40 can be increased, and as a result, the rigidity of the sliding member 40 can be increased. The high rigidity allows the sliding member 40 to be made smaller, and the shock absorbers 10, 200 to 500 can also be made smaller.

[0066] See FIGS. 2A and 2B (FIGS. 12 to 15). Third, in the shock absorber 10, 200 to 500 described above, preferably, the sliding member 40 is an integrally molded resin product. By forming the sliding member 40 as an integrally molded resin product, the weight of the sliding member 40 can be reduced. Furthermore, the cross-sectional areas A1 and A2 (see FIG. 8) between the inner circumferential surface 71 of the surrounding member 70 and the damping force generating portion 100 can be changed very easily by simply replacing the insert of the molding die. Furthermore, the damping force generating portion 100 is formed on the outer circumferential surface 41 of the sliding member 40 along the axial direction Rs. Therefore, no weld lines that affect the strength of the sliding member 40 are generated during resin molding. Therefore, the resin sliding member 40 can have appropriate strength. Additionally, by molding a sliding member 40 with a complex shape from resin, manufacturing costs can be reduced.

[0067] See Figures 2A to 3B (Figures 12 to 15). Fourth, preferably in the shock absorber 10, 200 to 500 described above, the surrounding member 70 is arranged on the inner circumferential surface 35 of the inner tube 30 so as to be movable in the axial direction Rs relative to the outer circumferential surface 41 of the sliding member 40, and is positioned closer to the open end 32 of the inner tube 30 (the second end 32 side) than the first partition wall 60, thereby constituting the second partition wall 70 that divides the inside and outside of the inner tube 30 in the axial direction Rs. The damping force generating portion 100 is constituted by at least one communicating portion 101 that communicates with at least one of the first partition wall 60 and the second partition wall 70 so as to straddle the axial direction Rs (penetrating in the axial direction Rs).

[0068] The communication portion 101 constituting the damping force generating portion 100 communicates with at least one of the first partition wall portion 60 and the second partition wall portion 70 so as to straddle the first partition wall portion 60 and the second partition wall portion 70 in the axial direction Rs (penetrating the first partition wall portion 60 and the second partition wall portion 70 in the axial direction Rs). Flow path resistance is generated when the hydraulic fluid passes through the communication portion 101. A simple configuration of simply forming the communication portion 101 on the outer circumferential surface 41 of the sliding member 40 is sufficient to generate the flow path resistance.

[0069] See Figures 5A to 5D. Fifth, in the shock absorber 10, 200 to 500 described above, preferably, the communicating portion 101 (first communicating portion 110) is formed in the first partition wall portion 60, and is configured by a portion 111 in which, in a cross section perpendicular to the center line CL of the sliding member 40, a distance a2 from the center line CL is shorter than a distance a1 from the center line CL to the outer peripheral surface 61 of the first partition wall portion 60. In this way, the communicating portion 101 (first communicating portion 110) is configured by a recess recessed from the outer peripheral surface 61 of the first partition wall portion 60. For this reason, the flow of hydraulic fluid passing through the recessed communicating portion 101 is not obstructed.

[0070] See FIGS. 5A to 5D. Sixth, preferably in the shock absorber 10, 200 to 500 described above, the communicating portion 101 (second communicating portion 120) is formed in the rod 50 and is configured by a portion 121 in which, in a cross section perpendicular to the center line CL of the sliding member 40, the distance b2 from the center line CL is shorter than the distance b1 from the center line CL to the outer peripheral surface 55 of the rod 50. In this manner, the communicating portion 101 (second communicating portion 120) is configured by a recess recessed from the outer peripheral surface 55 of the rod 50. Therefore, the flow of hydraulic fluid passing through the recessed communicating portion 101 is not obstructed. See FIGS. 5A to 5D. Seventh, preferably in the shock absorber 10, 200 to 500 described above, the communicating portion 101 is multiple. By providing multiple communicating portions 101, the cross-sectional areas A1 and A2 (see FIG. 8) and cross-sectional shapes of the individual communicating portions 101 can be set independently. The flow resistance that occurs when the hydraulic fluid passes through each of the communication portions 101 can be set more precisely.

[0071] See Figures 12A to 12C, 13A to 13C, and 14A to 14D. Eighth, in the shock absorber 200 to 400 preferably described in the first aspect, the communicating portion 220, 320, 420A to 420C is formed in the rod 50, and the cross-sectional areas A1, A2 vary along the center line CL of the sliding member 40. Therefore, by having the cross-sectional areas A1, A2 of the communicating portions 220, 320, 420A to 420C vary in the axial direction Rs, the flow resistance generated in accordance with the amount of expansion and contraction of the inner tube 30 can be set more precisely. As a result, the damping force generated in accordance with the amount of expansion and contraction of the inner tube 30 can be set as desired and precise.

[0072] See Figures 5A to 5D. Ninth, in the shock absorber 10, 200 to 500 described above, preferably, the cross-sectional areas A1 and A2 of the communication portion 101 are set so that they are larger on the side opposite the first partition wall portion 60 than on the side adjacent the first partition wall portion 60 (A1 < A2). By setting the first cross-sectional area A1 of the first communication portion 110 smaller than the second cross-sectional area A2 of the second communication portion 120 (A1 < A2), the flow resistance generated by the hydraulic fluid passing through the first communication portion 110 when the inner tube 30 extends (the extension stroke) is large. Therefore, by adjusting the first cross-sectional area A1 of the first communication portion 110, the flow resistance during the extension stroke can be optimized. As a result, the damping force during the extension stroke can be optimized.

[0073] See Figure 8. Tenth, in the shock absorber 10, 200 to 500, preferably the first described shock absorber, the communication portion 101 is configured by a first communication portion 110 formed in the first partition wall portion 60 and a second communication portion 120 formed in the rod 50. In a cross section perpendicular to the center line CL of the sliding member 40, the first cross-sectional area A1 of the first communication portion 110 and the second cross-sectional area A2 of the second communication portion 120 are set to adjust the damping force.

[0074] Therefore, when adjusting the damping force, the first cross-sectional area A1 of the first communication portion 110 and the second cross-sectional area A2 of the second communication portion 120 can be more appropriately set to be optimal. For example, when the inner tube 30 expands (expansion stroke), adjusting the flow resistance generated by the hydraulic fluid passing through the first communication portion 110 and the second communication portion 120 is effective in adjusting the damping force. More specifically, when the inner tube 30 expands, the flow resistance generated by the hydraulic fluid passing through the first communication portion 110 (first flow resistance) can be roughly adjusted, and the flow resistance generated by the hydraulic fluid passing through the second communication portion 120 (second flow resistance) can be finely adjusted, thereby adjusting the damping force to be optimal. Furthermore, when the inner tube 30 compresses (compression stroke), adjusting the flow resistance generated by the hydraulic fluid passing through the second communication portion 120 is effective in adjusting the damping force.

[0075] 15A to 15C. Eleventh, in the shock absorber 500, preferably as described above, the first communicating portion 110 and the second communicating portion 120 are positioned in different directions in a cross section perpendicular to the center line CL of the sliding member 40. As a result, the flow direction of the working fluid passing through the first communicating portion 110 and the flow direction of the working fluid passing through the second communicating portion 120 can be changed. This makes it possible to more precisely set the flow path resistance caused by the passage of the working fluid compared to when the first communicating portion 110 and the second communicating portion 120 are positioned in the same direction.

[0076] See Figures 2A, 11A, and 11B. Twelfth, preferably in the shock absorber 10, 200 to 500 described above, the rod 50 has a first end surface 51 opposite to the first partition wall portion 60, which has a fastening portion 54 (internal threads 54) that can be fastened to one end 21 of the outer tube 20 with a screw member 53. The first partition wall portion 60 has an end surface 64 opposite to the rod 50, which has a recess 65 into which a jig Jg that restricts rotation of the sliding member 40 can be inserted. The fastening portion 54 and the recess 65 are configured as an integrally molded product together with the resin sliding member 40.

[0077] When fastening the base end surface 51 of the rod 50 to the closing part 23 with the screw member 53, the jig Jg is hooked onto the recess 65 and pressed down. This prevents the sliding member 40 from rotating together with the screw member 53. Therefore, the work of attaching the sliding member 40 to the closing part 23 can be easily performed.

[0078] The shock absorbers 10, 200 to 500 according to the present invention are not limited to the above-described embodiments, as long as they achieve the functions and effects of the present invention. The shock absorbers 10, 200 to 500 are not limited to applications in which they are mounted on vehicles such as saddle-ride vehicles and automobiles, but can also be mounted on buildings and various types of equipment, for example.

[0079] The shock absorbers 10, 200 to 500 of the present invention are suitable for application to front forks and rear dampers mounted on saddle-ride type vehicles.

[0080] 10,200 to 500... shock absorber, 20... outer tube, 21... one end (first end), 22... other end (second end), 30... inner tube, 31... one end (first end), 32... other end (second end, open end), 34... interior, 35... inner circumferential surface, 36... first chamber, 37... second chamber, 38... third chamber, 40... sliding member, 41... outer circumferential surface, 50... rod, 51... first end face, 52... second end face, 53... screw member, 54... fastening portion (female thread), 55... outer circumferential surface of rod, 60... first partition wall portion, 61... outer circumferential surface, 64... end face, 65... recess, 70... surrounding member (second partition wall portion), 100... damping force generating portion, 101... communicating portion, 110...first communicating portion (first groove), 111...portion with short distance from center line, 120, 220, 320...second communicating portion (second groove), 121...portion with short distance from center line, a1, a2, b1, b2...distance, A1...cross-sectional area of ​​first communicating portion, A2...cross-sectional area of ​​second communicating portion, CL...center line, Jg...jig (tool), Rs...axial direction of outer tube.

Claims

1. A shock absorber comprising: a cylindrical outer tube; a cylindrical inner tube, at least a portion of which is fitted into the inside of the outer tube so as to be movable relative to the outer tube in the axial direction; a sliding member having a rod extending from one end of the outer tube into the inside of the inner tube and a first partition portion provided on the rod and in sliding contact with the inner circumferential surface of the inner tube to divide the inside of the inner tube into a first chamber and a second chamber; an enclosing member that is a member movable together with the inner tube relative to the outer tube, and which surrounds at least a portion of the outer circumferential surface of the sliding member in the axial direction; and a damping force generating portion formed on the outer circumferential surface of the sliding member along the axial direction, which is capable of generating a damping force between the outer circumferential surface of the enclosing member and the sliding member.

2. The shock absorber according to claim 1, wherein the sliding member is made of a solid material.

3. The shock absorber according to claim 2, wherein the sliding member is a one-piece molded resin part.

4. A shock absorber as described in claim 1, wherein the surrounding member is arranged on the inner peripheral surface of the inner tube so as to be movable in the axial direction relative to the outer peripheral surface of the sliding member, and is positioned closer to the open end of the inner tube than the first partition wall, thereby forming a second partition wall that separates the inside and outside of the inner tube in the axial direction, and the damping force generating portion is formed by at least one communication portion that communicates with at least one of the first partition wall and the second partition wall so as to straddle the axial direction.

5. A shock absorber as described in claim 4, wherein the communication portion is formed in the first partition wall portion and is configured by a portion whose distance from the center line is shorter than the distance from the center line to the outer peripheral surface of the first partition wall portion in a cross section perpendicular to the center line of the sliding member.

6. A shock absorber as described in claim 4, wherein the communicating portion is formed in the rod and is constituted by a portion that, in a cross section perpendicular to the center line of the sliding member, is closer to the center line than the distance from the center line to the outer peripheral surface of the rod.

7. The shock absorber according to claim 4, wherein the communication portion is plural.

8. The shock absorber according to claim 4, wherein the communicating portion is formed in the rod and has a cross-sectional area that varies along the center line of the sliding member.

9. The shock absorber according to claim 8, wherein the cross-sectional area of ​​the communication portion is set so as to be larger on the side opposite to the first partition portion than on the first partition portion side.

10. A shock absorber as described in claim 4, wherein the communication portion is constituted by a first communication portion formed in the first partition portion and a second communication portion formed in the rod, and the damping force can be adjusted by setting the first cross-sectional area of ​​the first communication portion and the second cross-sectional area of ​​the second communication portion in a cross section perpendicular to the center line of the sliding member.

11. The shock absorber according to claim 10, wherein the first communicating portion and the second communicating portion are positioned in different directions in a cross section perpendicular to the center line of the sliding member.

12. A shock absorber as described in claim 3, wherein a first end face of the rod opposite the first partition wall portion has a fastening portion that can be fastened to the one end of the outer tube with a screw member, and an end face of the first partition wall opposite the rod has a recess into which a jig that restricts rotation of the sliding member can be inserted, and the fastening portion and the recess are formed as a single unit together with the sliding member made of resin.

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