Shock absorber

Abstract

A shock absorber (20) comprises: an outer tube (30); an inner tube (40) that is fitted into the outer tube (30); a partition member (121) that partitions a space (100) between the inner tube (40) and the outer tube (30) into a first chamber (101), which is located on the insertion end side of the inner tube (40), and a second chamber (102); a check valve (122) that is included in the partition member (121) and that allows a hydraulic fluid to flow only from the first chamber (101) to the second chamber (102); a connection part (46) that connects the second chamber (102) and an internal space (41) of the inner tube (40); and a gap-forming member (130) that is fitted to the inner circumferential surface (44) of the inner tube (40) with a gap (140) therebetween. The gap (140) forms a flow path between the internal space (41) and the first chamber (101).

Description

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[0001] The present invention relates to a shock absorber that is particularly suitable for use in a saddle-ride type vehicle on which a passenger straddles the vehicle.

[0002] Saddle-ride vehicles, such as motorcycles and three-wheeled vehicles, are equipped with front forks. Some of the energy, such as vibrations, received from the road surface while the saddle-ride vehicle is traveling is damped by the front fork that supports the front wheel. Shock absorbers that make up the front fork include an upright type in which an inner tube on the vehicle body side moves back and forth relative to an outer tube on the axle side, and an inverted type in which an inner tube on the axle side moves back and forth relative to an outer tube on the vehicle body side. Prior art related to inverted shock absorbers is known, for example, from Patent Document 1.

[0003] The shock absorber disclosed in Patent Document 1 is an inverted shock absorber in which an inner tube is slidably inserted inside an outer tube, and an annular oil chamber is defined between the inner periphery of the outer tube and the outer periphery of the inner tube. This shock absorber includes an internal partition member disposed inside the inner tube, a partition check valve disposed in the internal partition member, a piston rod extending from the upper end of the outer tube through the internal partition member into the inner tube, and a piston disposed at the tip of the piston rod. The piston divides the oil chamber inside the inner tube into two oil chambers. The shock absorber further includes an oil chamber formed by the piston and the internal partition member and an oil hole disposed in the inner tube that connects the oil chamber to the annular oil chamber.

[0004] JP 2011-112160 A

[0005] The inverted shock absorber known from Patent Document 1 requires, as a damping force generating mechanism, a piston rod that extends from the upper end of the outer tube through the internal partition member into the inner tube, and a piston attached to the tip of this piston rod. This results in a complex configuration with a large number of parts, and therefore leaves room for improvement in terms of reducing costs.

[0006] An object of the present invention is to provide a technology for an inverted shock absorber that can reduce costs by using a simple configuration with a small number of parts to generate a damping force.

[0007] After extensive research, the inventors of the present invention have noticed that it is not necessary to provide a piston rod or piston to generate a damping force. They have discovered that it is possible to generate a damping force by providing flow resistance to the hydraulic fluid without providing a piston. The present invention was completed based on this discovery.

[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 outer tube so as to be relatively movable in the axial direction; a partition member whose fluctuation in relative position in the axial direction with respect to the inner tube is restricted, and which divides the space between the outer surface of the inner tube and the inner surface of the outer tube into a first chamber on the insertion end side of the inner tube and a second chamber on the opposite side of the first chamber in the axial direction; a check valve provided in the partition member, which allows the flow of working fluid from the first chamber to the second chamber and restricts the flow of the working fluid from the second chamber to the first chamber; a communicating portion which connects the internal space of the inner tube with the second chamber; and a gap forming member fitted into the inner surface of the inner tube, which forms a flow path for the working fluid flowing between the internal space of the inner tube and the first chamber and has a gap which imparts flow resistance to the working fluid.

[0009] The present disclosure can provide a technology for an inverted shock absorber that can reduce costs by using a simple configuration with a small number of parts to generate a damping force.

[0010] 5A is a front view of a front fork according to Example 1. FIG. 5B is a cross-sectional view of the shock absorber shown in FIG. 1. FIG. 5C is a schematic view of the shock absorber shown in FIG. 2. FIG. 5D is an enlarged view of the lower portion and surrounding area of ​​the shock absorber shown in FIG. 2. FIG. 5A is a diagram of modified example 1 of the bolt retainer shown in FIG. 4, FIG. 5B is a diagram of modified example 2 of the bolt retainer shown in FIG. 4, FIG. 5C is a diagram of modified example 3 of the bolt retainer shown in FIG. 4, and FIG. 5D is a diagram of modified example 4 of the bolt retainer shown in FIG. 4. FIG. 5B is an enlarged view of the open end of the outer tube and the rebound spring and surrounding area shown in FIG. 2. FIG. 5C is an enlarged view of the upper portion and surrounding area of ​​the shock absorber shown in FIG. 2. FIG. 5B is a cross-sectional view taken along line 8-8 in FIG. 3. FIG. 5C is an operation diagram of the shock absorber shown in FIG. 3 during the extension stroke. FIG. 5D is an operation diagram of the shock absorber shown in FIG. 3 during the compression stroke. FIG. 5C is a schematic view of a shock absorber according to Example 2. FIG. 12A is a schematic view of a shock absorber according to Example 3, and FIG. 12B is a cross-sectional view taken along line 12B-12B in FIG. 12A. Fig. 13A is a schematic diagram of a shock absorber according to Example 4 in a state where it is fully extended, Fig. 13B is a schematic diagram of a shock absorber shown in Fig. 13A in a state where it is fully compressed, Fig. 13C is a damping force characteristic diagram of the shock absorber shown in Fig. 13A in a state where it is extended nearly to its fullest extent, and Fig. 13D is a damping force characteristic diagram of the shock absorber shown in Fig. 13B in a state where it is compressed nearly to its fullest extent. Fig. 15A is a schematic diagram of a shock absorber according to Example 6 in a state where it is at an intermediate length in the extension direction, Fig. 15B is a schematic diagram of the shock absorber shown in Fig. 15A in a state where it is extended to its fullest extent, Fig. 15C is a damping force characteristic diagram of the shock absorber shown in Fig. 15A in a state where it is at an intermediate length, and Fig. 15D is a damping force characteristic diagram of the shock absorber shown in Fig. 15B in a state where it is extended nearly to its fullest extent. Figure 16A is a schematic diagram of the shock absorber according to Example 7 at an intermediate length in the extension direction, Figure 16B is a schematic diagram of the shock absorber shown in Figure 16A at its minimum extension, Figure 16C is a damping force characteristic diagram of the shock absorber shown in Figure 16A at its intermediate length, and Figure 16D is a damping force characteristic diagram of the shock absorber shown in Figure 16B at its minimum compression.

[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 20 according to a first embodiment will be described with reference to FIGS. 1 to 10. FIG.

[0013] As shown in Figure 1, the shock absorber 20 can be mounted on a front fork 10. The front fork 10 is used in saddle-ride vehicles such as motorcycles and three-wheeled vehicles. The front fork 10 includes a pair of shock absorbers 20, 20 that can be mounted on either side of a front wheel (not shown), a bracket 11 (bridge 11) that connects the upper ends of the shock absorbers 20, 20, and a steering stem 12 that extends upward from the center of the bracket 11.

[0014] Here, the upper end direction of the shock absorbers 20, 20 when assembled to the front fork 10 is referred to as Up, and the lower end direction thereof is referred to as Down. The axial direction of the shock absorber 20 refers to the direction along the center line CL of the shock absorber 20 (vertical direction Up-Dn).

[0015] The pair of shock absorbers 20, 20 are of a telescopic inverted type configuration, including outer tubes 30, 30 on the vehicle body side that are connected to the bracket 11, and inner tubes 40, 40 on the axle side that can move forward and backward relative to the outer tubes 30, 30. The stroke in which the shock absorbers 20, 20 contract is called the compression stroke, and the stroke in which the shock absorbers 20, 20 extend is called the extension stroke. Because the pair of shock absorbers 20, 20 have the same configuration, one of the shock absorbers 20 will be described in detail below.

[0016] As shown in Figures 2 and 3, the outer tube 30 (first tube 30) and the inner tube 40 (second tube 40) are arranged in the axial direction (up-down direction Up-Dn) along the center line CL of the shock absorber 20. The outer tube 30 is a cylindrical member with a uniform inner diameter. The inner tube 40 is a cylindrical member with uniform inner and outer diameters. At least a portion of the inner tube 40 is fitted inside the outer tube 30 so as to be relatively movable in the axial direction. The center line CL of the shock absorber 20 may be referred to as the "center line CL of the outer tube 30" or the "center line CL of the inner tube 40" as appropriate. Furthermore, the axial direction of the shock absorber 20 may be referred to as the "axial direction of the outer tube 30" or the "axial direction of the inner tube 40" as appropriate.

[0017] The outer tube 30 and the inner tube 40 are biased by a compression coil spring 50 in a direction that vertically separates them from each other. This compression coil spring 50 is located along the center line CL of the shock absorber 20 and is disposed in the internal space 41 of the inner tube 40. The upper end 31 of the outer tube 30 is liquid-tightly closed by a closing member 32. The upper end 42 of the inner tube 40 is an open end. The lower end 43 of the inner tube 40 is a closed end that is closed by a bottom piece 61.

[0018] 4, a retaining ring 62 hooked onto the inner circumferential surface 44 of the inner tube 40 prevents the bottom piece 61 from falling below the lower end 43 of the inner tube 40. Furthermore, a sealing member 63 such as an O-ring provides a liquid-tight seal between the inner circumferential surface 44 of the inner tube 40 and the outer circumferential surface 61a of the bottom piece 61. As a result, leakage of the hydraulic fluid present in the internal space 41 of the inner tube 40 can be prevented, and rainwater can be prevented from entering the inner tube 40 from the outside. The bottom piece 61 serves as a spring bearing that receives the lower end of the compression coil spring 50.

[0019] Furthermore, the lower end 43 of the inner tube 40 is fitted inside an axle bracket 70 that supports the front wheel axle. A headed bolt 73 (center bolt 73) is inserted axially from the outside into a through-hole 72 in the bottom 71 of the axle bracket 70. This center bolt 73 is threaded into the bottom piece 61. The axial force generated by this threading is applied to the retaining ring 62, the lower end 43 of the inner tube 40, and the thread bearing surfaces between the bottom piece 61 and the axle bracket 70, thereby securing the axle bracket 70 to the inner tube 40. A sealing member 75, such as an O-ring, seals the gap between the outer peripheral surface 45 of the inner tube 40 and the inner peripheral surface 74 of the axle bracket 70. As a result, foreign matter such as rainwater and mud can be prevented from entering the axle bracket 70 from the outside.

[0020] As shown in Figures 5A to 5D, it is preferable that the center bolt 73 be prevented from coming loose from the axle bracket 70. Figure 5A shows an example in which the center bolt 73 is prevented from coming loose by at least one of bolts 81 to 83 that are screwed radially into the axle bracket 70. These bolts 81 to 83 may be set screws (also known as hollow screws) with threads formed on the entire outer periphery. The first bolt 81 is configured to press the threaded portion of the center bolt 73 with its tip to prevent loosening. The second bolt 82 is configured to press the head of the center bolt 73 with its tip to prevent loosening. The third bolt 83 is configured to extend to the radial center of the axle bracket 70, thereby restricting axial movement of the center bolt 73 and preventing it from coming loose.

[0021] Figure 5B shows a configuration in which a retaining ring 84, such as a circlip or washer, attached to the axle bracket 70 prevents the center bolt 73 from moving axially and prevents it from coming loose. Figure 5C shows a configuration in which a pin 85 (including a split pin) that penetrates radially through the axle bracket 70 prevents the center bolt 73 from moving axially and prevents it from coming loose. The tip of the pin 85 is prevented from coming loose by a split pin 86. Figure 5D shows that a member 87 that penetrates radially through the axle bracket 70 and prevents the center bolt 73 from moving axially and prevents it from coming loose is a metal or non-metallic part.

[0022] As shown in Figure 6, the gap between the open end 33 (lower end 33) of the outer tube 30 and the outer peripheral surface 45 of the inner tube 40 is liquid-tightly sealed by a sealing member 91 such as an oil seal. As a result, leakage of the hydraulic fluid present in the space 100 of the outer tube 30 can be prevented, and foreign matter such as rainwater and mud can be prevented from entering the outer tube 30 from the outside. This sealing member 91 is integrally formed by an annular metal core member 92 and an elastic sealing portion 93. The core member 92 is located on the outer peripheral side of the sealing member 91 and protects the sealing portion 93.

[0023] More specifically, a stepped surface 35 is formed inside the open end 34 of the outer tube 30. Inside this stepped surface 35, a flat washer 94, a seal member 91, and an L-shaped cross-section annular washer 95 are fitted, in this order, axially outward from the stepped surface 35. Furthermore, a retaining ring 96 is fitted axially outward from the outer tube 30 into the open end 34 of the outer tube 30 to prevent the seal member 91 and annular washer 95 from coming off.

[0024] The annular washer 95 is a metal product that is integrally formed with a receiving portion 97 made of an annular flat plate that receives the end face of the seal member 91, and a cylindrical cover portion 98 that extends from the inner peripheral surface of the receiving portion 97 outward in the axial direction of the outer tube 30. The cover portion 98 is positioned so as to cover the inner peripheral surface of the retaining ring 96, and prevents the retaining ring 96 from deforming radially inward and coming off.

[0025] As shown in FIG. 6 , a rebound spring 111 is disposed in a space 100 between the inner circumferential surface 36 of the outer tube 30 and the outer circumferential surface 45 of the inner tube 40. The rebound load of this rebound spring 111 can be supported by a spring bearing portion 112 and a bushing 113. The spring bearing portion 112 is provided on the outer circumferential surface 45 of the inner tube 40 and supports the rebound load from one end (upper end) of the rebound spring 111. The bushing 113 is a cylindrical member provided on the inner circumferential surface 36 of the outer tube 30 and is in axial contact with the flat washer 94 on the seal member 91 side. The end face of this bushing 113 on the rebound spring 111 side can be in contact with the rebound spring 111.

[0026] When the shock absorber 20 rebounds during the extension stroke, the rebound load is transmitted from the rebound spring 111 to the outer tube 30 via the bushing 113, flat washer 94, core material 92 of the seal member 91, annular washer 95, and retaining ring 96. Because the rebound load is received by the core material 92 of the seal member 91, an excessive rebound load is not applied to the seal portion 93 of the seal member 91. This ensures the durability of the seal portion 93, which is made of an elastic material.

[0027] As shown in Figures 3 and 7, the shock absorber 20 includes a partition member 121 that partitions the space 100 between each tube 30, 40 into a first chamber 101 and a second chamber 102, a check valve 122 provided in this partition member 121, a communication portion 46 (first communication portion 46) that communicates the internal space 41 of the inner tube 40 with the second chamber 102, and a gap forming member 130 that fits into the inner surface 44 of the inner tube 40.

[0028] The first chamber 101 is a portion of the space 100 on the insertion end 42 side of the inner tube 40 (on the upper end 31 side of the outer tube 30). The second chamber 102 is a portion of the space 100 on the opposite side of the axial direction from the first chamber 101 (on the lower end 33 side of the outer tube 30).

[0029] The partition member 121 has a function of a piston, and fluctuation in its position relative to the inner tube 40 in the axial direction is restricted. For example, the partition member 121 is movable in the axial direction together with the inner tube 40, and is preferably provided on the outer peripheral surface 45 of the inner tube 40. The check valve 122 is configured to allow the flow of hydraulic fluid from the first chamber 101 to the second chamber 102, and to restrict the flow of hydraulic fluid from the second chamber 102 to the first chamber 101.

[0030] The first communication portion 46 is formed by at least one through-hole that penetrates between the inner circumferential surface 44 and the outer circumferential surface 45 of the inner tube 40 (penetrating inward and outward in the radial direction).

[0031] The gap forming member 130 is a member that can move relatively in the axial direction inside the inner tube 40 and is fitted onto the inner circumferential surface 44 of the inner tube 40. This gap forming member 130 is a cylindrical member with a uniform outer diameter throughout, and has a so-called straight pipe configuration. Furthermore, this gap forming member 130 is preferably located on the center line CL of the inner tube 40. A gap 140 is formed between the inner circumferential surface 44 of the inner tube 40 and the outer circumferential surface 131 of the gap forming member 130. This gap 140 (tubular gap 140) forms a flow path for the working fluid that flows between the internal space 41 of the inner tube 40 and the first chamber 101, and is set to a size that can impart flow resistance to the passing working fluid.

[0032] More specifically, the gap forming member 130 is configured as a separate part or as an integrated part with respect to the outer tube 30. Here, a description will be given of the gap forming member 130 configured as a separate part. The gap forming member 130 comprises a cylindrical tube portion 132 that is fitted to the inner circumferential surface 44 of the inner tube 40 with a gap 140 therebetween so as to be relatively movable, and a partition portion 133 that separates the interior 132a of the tube portion 132 from the internal space 41 of the inner tube 40. The interior 132a of the tube portion 132 may be referred to as the "internal space 132a of the gap forming member 130" as appropriate.

[0033] The cylindrical portion 132 has a uniform outer diameter. The upper end 132b of the cylindrical portion 132 is a flat surface that can abut against the flat inner surface 32a of the closing member 32 and opens toward the inner surface 32a. The partition portion 133 is provided at the axial end 132c of the cylindrical portion 132 and also serves as a spring bearing portion that receives one end (upper end) of the compression coil spring 50. The compression coil spring 50 is interposed between the partition portion 133 of the gap forming member 130 and the bottom piece 61 with a biasing force. The gap forming member 130 is pressed against the closing member 32 by the biasing force of the compression coil spring 50. As a result, the outer tube 30 is biased against the compression coil spring 50 via the gap forming member 130.

[0034] Furthermore, the gap forming member 130 has a hole 134 (second communication portion 134) that can communicate between the interior 132a of the tubular portion 132 and the gap 140, and a hole 135 (third communication portion 135) that penetrates the partition portion 133. The opening area of ​​the second communication portion 134 is set larger than the opening area of ​​the third communication portion 135. The opening area of ​​the gap 140 (tubular gap 140) is set larger than the opening area of ​​the third communication portion 135.

[0035] 3 and 8 , when the outer tube 30 is viewed in the axial direction, the area A1 of the second chamber 102 is set to be larger than the area A2 of the internal space 41 of the inner tube 40. Here, the area A1 of the second chamber 102 refers to the cross-sectional area surrounded by the inner circumferential surface 36 of the outer tube 30 and the outer circumferential surface 45 of the inner tube 40. The area A2 of the internal space 41 refers to the cross-sectional area surrounded by the inner circumferential surface 44 of the inner tube 40.

[0036] Next, the operation of the shock absorber 20 of the first embodiment will be described with reference to Figures 9 and 10. Figure 9 shows the flow of hydraulic fluid when the shock absorber 20 is in an extension stroke (when the outer tube 30 extends in the direction of arrow Re). Figure 10 shows the flow of hydraulic fluid when the shock absorber 20 is in a compression stroke (when the outer tube 30 contracts in the direction of arrow Rc).

[0037] Where appropriate, the internal space 41 of the inner tube 40 may be referred to as the "compression chamber 41," the first chamber 101 as the "reservoir chamber 101," the second chamber 102 as the "extension chamber 102," and the internal space 132a of the gap forming member 130 as the "air chamber 132a."

[0038] Whether the shock absorber 20 is in the extension stroke or the compression stroke, the gap forming member 130 imparts flow resistance to the hydraulic fluid that passes through the gap 140 and flows into the first chamber 101 (reservoir chamber 101). Furthermore, when the shock absorber 20 is in the compression stroke, the gap forming member 130 moves in a direction that compresses the internal space 41 (compression chamber 41) of the inner tube 40, thereby functioning as a "pump" that sends the hydraulic fluid in this compression chamber 41 into the second chamber 102 (extension chamber 102).

[0039] When the shock absorber 20 is in the extension stroke, the partition member 121 compresses the second chamber 102 (extension chamber 102) to increase the internal pressure. When the shock absorber 20 is in the compression stroke, the partition member 121 allows the flow of hydraulic fluid from the first chamber 101 (reservoir chamber 101) to the second chamber 102 (extension chamber 102) by opening the check valve 122.

[0040] As shown in Figure 9, when the shock absorber 20 is in the extension stroke, the hydraulic fluid in the second chamber 102 (extension chamber 102) flows through the communication part 46 into the internal space 41 (compression chamber 41) of the inner tube 40. At this time, flow resistance is applied to the hydraulic fluid passing through the first communication part 46. In other words, a pressure difference occurs before and after the first communication part 46, causing the pressure in the second chamber 102 (extension chamber 102) to rise, which applies flow resistance to the hydraulic fluid and produces a damping effect during the extension stroke. The check valve 122 is closed.

[0041] Furthermore, the hydraulic fluid corresponding to the difference between the area A1 of the extension chamber 102 and the area A2 of the compression chamber 41 flows from the internal space 41 (compression chamber 41) through the tubular gap 140 to the reservoir chamber 101. At this time, flow resistance is imparted to the hydraulic fluid passing through the tubular gap 140, causing a damping effect during the extension stroke.

[0042] 10 , when the shock absorber 20 is in the compression stroke, the hydraulic fluid in the internal space 41 (compression chamber 41) of the inner tube 40 flows through the first communication portion 46 to the second chamber 102 (extension chamber 102), and also flows through the "gap 140" between the inner circumferential surface 44 of the inner tube 40 and the gap forming member 130 to the first chamber 101 (reservoir chamber 101). The hydraulic fluid in the first chamber 101 flows through the check valve 122 to the second chamber 102. At this time, the pressure in the internal space 41 of the inner tube 40 increases, generating a force that pushes the gap forming member 130 axially upward toward the outer tube 30, thereby producing a damping effect during the compression stroke.

[0043] During the compression stroke shown in FIG. 10 , if the hydraulic fluid in the compression chamber 41 simply flows through the first communication portion 46 to the extension chamber 102, the flow resistance of the hydraulic fluid passing through the first communication portion 46 would result in a large damping effect during the compression stroke. In response to this, the shock absorber 20 includes a tubular gap 140 in addition to the first communication portion 46. The opening area of ​​the tubular gap 140 is preferably larger than the opening area of ​​the first communication portion 46. The hydraulic fluid in the compression chamber 41 flows through the tubular gap 140 to the reservoir chamber 101, and then flows from the reservoir chamber 101 through the check valve 122 to the extension chamber 102. This reduces the damping force during the compression stroke. This improves the ride comfort of the saddle-ride type vehicle.

[0044] <Embodiment 2> A shock absorber 200 of embodiment 2 will be described with reference to Fig. 11. Fig. 11 is a cross-sectional view illustrating the shock absorber 200 of embodiment 2, and corresponds to Fig. 3 which illustrates the shock absorber 20 of embodiment 1. The shock absorber 200 of embodiment 2 is characterized in that the size of the first communication portion 46 of embodiment 1 shown in Fig. 3 is enlarged to a first communication portion 246 shown in Fig. 11. The rest of the basic configuration is common to the shock absorber 20 of embodiment 1. The same reference numerals will be used for parts common to the shock absorber 20 of embodiment 1, and detailed description thereof will be omitted.

[0045] In the shock absorber 200 of the second embodiment, as in the first embodiment, as shown in Fig. 8, the area A1 of the second chamber 102 is set to be larger than the area A2 of the internal space 41 of the inner tube 40. As shown in Fig. 11, the size of the first communication portion 246 is preferably set to an extent that does not impart flow resistance to the hydraulic fluid passing through this first communication portion 246. When the shock absorber 200 is in the extension stroke, an amount of hydraulic fluid equivalent to the difference between the area A1 and the area A2 flows from the internal space 41 through the gap 140 to the first chamber 101 (reservoir chamber 101). By imparting flow resistance to the hydraulic fluid passing through the gap 140, a damping force can be generated during the extension stroke.

[0046] First, the damping force of the shock absorber 200 must be generated during the extension stroke. During the compression stroke, the force applied to the shock absorber 200 can be suppressed by the force of the compression coil spring 50. The shock absorber 200 is specialized in generating a damping force during the extension stroke, and generates little or no damping force during the compression stroke.

[0047] Let us now consider again the shock absorber 20 of the first embodiment shown in Figures 9 and 10. The shock absorber 20 of the first embodiment can stably generate a damping force during the extension stroke by sufficiently sending the hydraulic fluid in the internal space 41 (compression chamber 41) to the second chamber 102 (extension chamber 102) during the compression stroke. More specifically, the volume of the extension chamber 102 increases during the compression stroke of the shock absorber 20. By sufficiently supplying hydraulic fluid corresponding to this increased volume from the compression chamber 41 to the extension chamber 102, the shock absorber 20 can generate a sufficient damping force during the extension stroke. In other words, the volume of the extension chamber 102 decreases during the extension stroke. If there is not enough hydraulic fluid remaining inside the extension chamber 102 at this time, air mixed in the hydraulic fluid will accumulate. When this air is compressed and the liquid level of the hydraulic fluid in the extension chamber 102 reaches the first communication portion 46 , the hydraulic fluid flows from the extension chamber 102 through the first communication portion 46 to the compression chamber 41 .

[0048] The first communication portion 46 functions as a throttle for generating a damping force during the extension stroke, and also acts as a resistance to the hydraulic fluid supplied from the compression chamber 41 to the extension chamber 102 during the compression stroke. During the compression stroke, the hydraulic fluid in the compression chamber 41 does not easily flow to the extension chamber 102, so a larger amount flows into the first chamber 101 (reservoir chamber 101). Therefore, supplying a larger amount of hydraulic fluid from the reservoir chamber 101 to the extension chamber 102 through the check valve 122 during the compression stroke leads to a stable generation of damping force during the extension stroke.

[0049] In contrast, in the shock absorber 200 of Example 2 shown in Figure 11, the first communication portion 246 is set larger than the first communication portion 46 shown in Figure 10, thereby allowing the compression chamber 41 and the extension chamber 102 to function as "one extension chamber." The area A1 of the extension chamber 102 is larger than the area A2 of the compression chamber 41 (A1 > A2). During the compression stroke, the hydraulic fluid in the compression chamber 41 flows to the extension chamber 102 and does not flow to the reservoir chamber 101. In this way, the shock absorber 200 of Example 2 is designed to prevent air from entering the extension chamber 102 by reducing the amount of hydraulic fluid supplied from the reservoir chamber 101 to the extension chamber 102, thereby generating a more stable damping force.

[0050] <Embodiment 3> A shock absorber 300 according to embodiment 3 will be described with reference to Figures 12A and 12B. Figure 12A corresponds to Figure 3. Figure 12B corresponds to Figure 8.

[0051] The shock absorber 300 of the third embodiment is characterized in that, when viewed in the axial direction of the outer tube 30, the area A2 of the internal space 41 (compression chamber 41) of the inner tube 40 is set larger than the area A1 of the second chamber 102 (extension chamber 102) (A1<A2). In other words, this is the opposite relationship to the "A1>A2" of the first embodiment shown in Figures 3 and 8.

[0052] Incidentally, which of the area A1 of the extension chamber 102 and the area A2 of the internal space 41 is larger is determined by the diameters of the outer tube 30 and the inner tube 40, which are determined by the requirements of the body of the saddle-ride type vehicle.

[0053] When the area A1 of the extension chamber 102 is larger than the area A2 of the compression chamber 41 (A1 > A2), as in the shock absorber 20 of the first embodiment shown in Figure 8, the flow of hydraulic fluid is as follows. During the extension stroke shown in Figure 9, hydraulic fluid in the extension chamber 102 flows into the compression chamber 41 through the first communication part 46. The amount of hydraulic fluid corresponding to the difference between the area A1 of the extension chamber 102 and the area A2 of the compression chamber 41 flows from the compression chamber 41 through the tubular gap 140 to the reservoir chamber 101. At this time, a damping force is generated by the parallel fluid path of the first communication part 46 and the tubular gap 140. During the compression stroke shown in Figure 10, negative pressure is created in the extension chamber 102. Hydraulic fluid in the compression chamber 41 fills the extension chamber 102 through the first communication part 46. The hydraulic fluid corresponding to the difference between the area A1 of the extension chamber 102 and the area A2 of the compression chamber 41 is filled into the extension chamber 102 from the reservoir chamber 101 through the check valve 122 .

[0054] 12A and 12B , when the area A2 of the compression chamber 41 is larger than the area A1 of the extension chamber 102 (A1<A2), the flow of hydraulic fluid is as follows. During the extension stroke, hydraulic fluid in the extension chamber 102 flows through the first communication part 46 to the compression chamber 41. At this time, because the volume of the compression chamber 41 is larger than that of the extension chamber 102, hydraulic fluid equivalent to the difference between the area A1 of the extension chamber 102 and the area A2 of the compression chamber 41 is filled from the reservoir chamber 101 through the tubular gap 140 to the compression chamber 41. A damping force is generated by the flow resistance of the first communication part 46 and the tubular gap 140. During the compression stroke, hydraulic fluid in the compression chamber 41 flows through the first communication part 46 to the extension chamber 102. The hydraulic fluid corresponding to the difference between the area A1 of the extension chamber 102 and the area A2 of the compression chamber 41 flows through the tubular gap 140 to the reservoir chamber 101. A damping force is generated by the flow resistance of the first communication portion 46 and the tubular gap 140.

[0055] However, if the hydraulic fluid in the compression chamber 41 only flows through the first communication portion 46 to the extension chamber 102 during the compression stroke of the shock absorber 300, the flow resistance of the hydraulic fluid passing through the first communication portion 46 will result in a large damping effect during the compression stroke. In response to this, the shock absorber 300 includes a tubular gap 140 in addition to the first communication portion 46. The opening area of ​​the tubular gap 140 is preferably larger than the opening area of ​​the first communication portion 46. The hydraulic fluid in the compression chamber 41 flows through the tubular gap 140 to the reservoir chamber 101, and then flows from the reservoir chamber 101 to the extension chamber 102 through the check valve 122. This reduces the damping force during the compression stroke. This improves the ride comfort of the saddle-ride type vehicle.

[0056] As is clear from the above explanation, the flow of the hydraulic fluid differs between the case of "A1>A2" in Example 1 shown in FIGS. 3 and 8 and the case of "A1<A2" in Example 3 shown in FIGS. 12A and 12B.

[0057] Other basic configurations are the same as those of the shock absorber 20 of Example 1. The same reference numerals will be used for the parts that are the same as those of the shock absorber 20 of Example 1, and detailed descriptions thereof will be omitted.

[0058] <Fourth Embodiment> A shock absorber 400 according to a fourth embodiment will be described with reference to Figures 13A to 13D. Figures 13A and 13B are cross-sectional views illustrating the shock absorber 400 according to the fourth embodiment, and correspond to Figure 3 illustrating the shock absorber 20 according to the first embodiment. The shock absorber 400 according to the fourth embodiment is characterized by increasing the damping force during the compression stroke when the shock absorber is compressed to nearly its minimum extent. The rest of the basic configuration is the same as that of the shock absorber 20 according to the first embodiment. The same reference numerals will be used for parts common to the shock absorber 20 according to the first embodiment, and detailed descriptions will be omitted.

[0059] 13A shows a state in which the shock absorber 400 is fully extended. In this state, the length (first length) by which the inner tube 40 and the gap forming member 130 overlap each other in the axial direction is the minimum L1. This first length L1 corresponds to the axial length of the gap 140 (the tubular gap 140).

[0060] 13B shows a state in which the shock absorber 400 is compressed to its minimum extent. In this state, the length (second length) by which the inner tube 40 and the gap forming member 130 overlap each other in the axial direction is the maximum L2. This second length L2 corresponds to the axial length of the gap 140 (tubular gap 140). Even in this minimum compressed state, the first communication portion 46 is not closed by the gap forming member 130.

[0061] In this way, as the axial lengths L1 and L2 of the gap 140 increase, the flow resistance of the hydraulic fluid passing through the gap 140 increases, resulting in an increase in the damping force.

[0062] 13C and 13D show the characteristics of the damping force Df versus the expansion / contraction speed Vp of the shock absorber 400, with the horizontal axis representing the expansion / contraction speed Vp of the shock absorber 400 and the vertical axis representing the damping force Df of the shock absorber 400. +Df is the damping force during the expansion stroke, and −Df is the damping force during the compression stroke.

[0063] Fig. 13C shows the damping force Df characteristics when shock absorber 400 is nearly fully extended (see Fig. 13A). Characteristic curve Q1 shows the change in damping force Df when the flow velocity of hydraulic fluid passing through gap 140 is low during the extension stroke. Similarly, characteristic curve Q2 shows the change in damping force Df when the flow velocity is high during the extension stroke. Characteristic curve Q3 shows the change in damping force Df when the flow velocity of hydraulic fluid passing through gap 140 is low during the compression stroke. Similarly, characteristic curve Q4 shows the change in damping force Df when the flow velocity is high during the compression stroke.

[0064] Fig. 13D shows the damping force Df characteristics when shock absorber 400 is compressed nearly to its minimum extent as shown in Fig. 13B. Characteristic curve Q1A shows the change in damping force Df when the flow velocity of hydraulic fluid passing through gap 140 is low during the extension stroke, and has a characteristic that the damping force is greater than that of characteristic curve Q1 in Fig. 13C because length L2 (second length L2) of gap 140 is longer. Similarly, characteristic curve Q2A shows the change in damping force Df when the flow velocity is high during the extension stroke, and has a characteristic that the damping force is greater than that of characteristic curve Q2 in Fig. 13C because length L2 (second length L2) is longer due to the longer length of gap 140.

[0065] Characteristic curve Q3A shows the change in damping force Df when the flow velocity of the hydraulic fluid passing through gap 140 is low during the compression stroke, and has a characteristic of increasing more than characteristic curve Q3 in Fig. 13C. Similarly, characteristic curve Q4A shows the change in damping force Df when the flow velocity is high during the compression stroke, and has a characteristic of increasing even more than characteristic curve Q4 in Fig. 13C.

[0066] This shows that when the shock absorber 400 is compressed to nearly its minimum extent, the damping force Df increases, particularly during the compression stroke, regardless of the flow velocity of the hydraulic fluid.

[0067] <Fifth Embodiment> A shock absorber 500 according to a fifth embodiment will be described with reference to Fig. 14. Fig. 14 is a cross-sectional view illustrating the shock absorber 500 according to the fifth embodiment, and corresponds to Fig. 3 illustrating the shock absorber 20 according to the first embodiment.

[0068] The shock absorber 500 of the fifth embodiment is characterized in that the gap forming member 130 of the first embodiment is replaced with a gap forming member 530 shown in Fig. 14. The other basic configuration is common to the shock absorber 20 of the first embodiment. The same reference numerals are used for the parts common to the shock absorber 20 of the first embodiment, and detailed description thereof will be omitted.

[0069] The gap forming member 530 of Example 5 has the same basic configuration as the gap forming member 130 of Example 1, but is characterized by being a stepped member. This gap forming member 530 includes a first cylindrical portion 532 on the distal end side having a gap 140 formed between the inner peripheral surface 44 of the inner tube 40 and the outer peripheral surface 531 of the gap forming member 530, a second cylindrical portion 533 on the proximal end side (closer to the closure member 32) having a smaller diameter than the first cylindrical portion 532, and a partition portion 133. That is, the gap forming member 530 of Example 5 is obtained by replacing the cylindrical portion 132 of the gap forming member 130 of Example 1 shown in FIG. 3 with the first cylindrical portion 532 and the second cylindrical portion 533 shown in FIG. 14. The length L11 of the second cylindrical portion 533 is a predetermined constant value. Therefore, regardless of the length L12 by which the inner tube 40 and the gap forming member 130 overlap each other in the axial direction, the flow resistance of the hydraulic fluid passing through the gap 140 can be kept constant (including almost constant).

[0070] <Sixth Example> A shock absorber 600 of the sixth example will be described with reference to Figures 15A to 15D. Figures 15A and 15B are cross-sectional views illustrating the shock absorber 600 of the sixth example, and correspond to Figure 3 illustrating the shock absorber 20 of the first example. The shock absorber 600 of the sixth example is characterized by achieving a rapid increase in damping force when extended to near its maximum extent. The other basic configurations are common to the shock absorber 20 of the first example. The same reference numerals will be used for parts common to the shock absorber 20 of the first example, and detailed descriptions will be omitted.

[0071] FIG. 15A shows a state in which the shock absorber 600 is at an intermediate length in the extension direction. The axial position of the first communication portion 46 relative to the inner tube 40 is defined as a communication position P1. A fixed relative movement distance St1 of the inner tube 40 in the extension direction relative to the gap forming member 130 is defined as a reference stroke St1. This reference stroke St1 corresponds to, for example, the distance that the shock absorber 600 (see FIG. 15A) moves from this intermediate length state to the fully extended state shown in FIG. 15B. Furthermore, this reference stroke St1 corresponds to, for example, the distance L21 from the axial center of the bushing 113 (see also FIG. 6) to the communication position P1 when the shock absorber 600 is at this intermediate length.

[0072] When the shock absorber 600 moves from the intermediate length state shown in Figure 15A to the fully extended state shown in Figure 15B, the first communication part 46 reaches a position where it is closed by the bushing 113. As a result, it becomes difficult for the hydraulic fluid in the second chamber 102 (extension chamber 102) to pass through the first communication part 46 and flow into the internal space 41 (compression chamber 41). When the shock absorber 600 is extended close to its maximum, the damping force increases sharply. Note that the communication position P1 of the first communication part 46 may be set when the shock absorber 600 is minimally compressed.

[0073] 15C and 15D show the characteristics of the damping force Df versus the expansion / contraction speed Vp of the shock absorber 600, with the horizontal axis representing the expansion / contraction speed Vp of the shock absorber 600 and the vertical axis representing the damping force Df of the shock absorber 600. +Df is the damping force during the expansion stroke, and −Df is the damping force during the compression stroke.

[0074] Figure 15C shows the damping force Df characteristics when the shock absorber 600 is at an intermediate length (see Figure 15A). Characteristic curve Q11 shows the change in damping force Df when the flow velocity of the hydraulic fluid passing through the first communication portion 46 is low during the extension stroke. Similarly, characteristic curve Q12 shows the change in damping force Df when the flow velocity is high during the extension stroke. Characteristic curve Q13 shows the change in damping force Df when the flow velocity of the hydraulic fluid passing through the first communication portion 46 is low during the compression stroke. Similarly, characteristic curve Q14 shows the change in damping force Df when the flow velocity is high during the compression stroke.

[0075] Fig. 15D shows the damping force Df characteristics when the shock absorber 600 is extended nearly to its maximum extent as shown in Fig. 15B. Characteristic curve Q11A shows the change in damping force Df when the flow velocity of hydraulic fluid passing through the first communication portion 46 is low during the extension stroke, and has a characteristic that the damping force Df increases compared to characteristic curve Q11 of Fig. 15C and increases rapidly particularly as the extension / retraction speed Vp of the shock absorber 600 increases. Similarly, characteristic curve Q12A shows the change in damping force Df when the flow velocity is high during the extension stroke, and has a characteristic that the damping force Df increases even more compared to characteristic curve Q12 of Fig. 15C and increases even more rapidly particularly as the extension / retraction speed Vp of the shock absorber 600 increases.

[0076] Characteristic curve Q13A shows the change in damping force Df when the flow velocity of the hydraulic fluid passing through the first communication portion 46 is low during the compression stroke, and has a characteristic of increasing more than characteristic curve Q13 in Figure 15C. Similarly, characteristic curve Q14A shows the change in damping force Df when the flow velocity is high during the compression stroke, and has a characteristic of increasing even more than characteristic curve Q14 in Figure 15C.

[0077] According to this, it can be seen that when the shock absorber 600 expands, the damping force Df increases rapidly when the shock absorber 600 is expanded to nearly its maximum extent, regardless of the flow velocity of the hydraulic fluid.

[0078] <Seventh Example> A shock absorber 700 of a seventh example will be described with reference to Figures 16A to 16D. Figures 16A and 16B are cross-sectional views illustrating the shock absorber 700 of the seventh example, and correspond to Figure 3 illustrating the shock absorber 20 of the first example. The shock absorber 700 of the seventh example is characterized by increasing the damping force when compressed to near the minimum. The other basic configurations are common to the shock absorber 20 of the first example. The same reference numerals are used for parts common to the shock absorber 20 of the first example, and detailed descriptions thereof will be omitted.

[0079] FIG. 16A shows a state in which the shock absorber 700 is at an intermediate length in the extension direction. The axial position of the first communicating portion 46 relative to the inner tube 40 is defined as the communicating position P2. A fixed relative movement distance St2 of the inner tube 40 in the compression direction relative to the gap forming member 130 is defined as the reference stroke St2. This reference stroke St2 corresponds to, for example, the distance that the shock absorber 700 (see FIG. 16A) moves from this intermediate length state to the minimally compressed state shown in FIG. 16B. Furthermore, this reference stroke St2 is also, for example, the amount of movement L22 by which the first communicating portion 46 shown in FIG. 16A can overlap the gap forming member 130 in the axial direction as shown in FIG. 16B.

[0080] When the shock absorber 700 moves from the intermediate length state shown in Figure 16A to the fully compressed state shown in Figure 16B, the first communication part 46 reaches a position where it is closed by the gap forming member 130. As a result, it becomes difficult for the hydraulic fluid in the second chamber 102 (extension chamber 102) to pass through the first communication part 46 and flow into the internal space 41 (compression chamber 41). When the shock absorber 700 is compressed close to its minimum, the damping force increases sharply. Note that the communication position P2 of the first communication part 46 may be set when the shock absorber 700 is fully extended.

[0081] 16C and 16D show the characteristics of the damping force Df versus the expansion / contraction speed Vp of the shock absorber 600, with the horizontal axis representing the expansion / contraction speed Vp of the shock absorber 600 and the vertical axis representing the damping force Df of the shock absorber 600. +Df is the damping force during the expansion stroke, and −Df is the damping force during the compression stroke.

[0082] Figure 16C shows the damping force Df characteristics when the shock absorber 600 is at an intermediate length (see Figure 16A). Characteristic curve Q21 shows the change in damping force Df when the flow velocity of the hydraulic fluid passing through the first communication portion 46 is low during the extension stroke. Similarly, characteristic curve Q22 shows the change in damping force Df when the flow velocity is high during the extension stroke. Characteristic curve Q23 shows the change in damping force Df when the flow velocity of the hydraulic fluid passing through the first communication portion 46 is low during the compression stroke. Similarly, characteristic curve Q24 shows the change in damping force Df when the flow velocity is high during the compression stroke.

[0083] Figure 16D shows the characteristics of the damping force Df when the shock absorber 600 is compressed nearly to its minimum extent as shown in Figure 16B. Characteristic curve Q21A shows the change in damping force Df when the flow velocity of the hydraulic fluid passing through the first communication portion 46 is low during the extension stroke, and has the same characteristics as characteristic curve Q21 in Figure 16C. Similarly, characteristic curve Q22A shows the change in damping force Df when the flow velocity is high during the extension stroke, and has the same characteristics as characteristic curve Q22 in Figure 16C.

[0084] Characteristic curve Q23A shows the change in damping force Df when the flow velocity of hydraulic fluid passing through the first communication portion 46 is low during the compression stroke, and has a characteristic in which the damping force Df increases particularly when the expansion / contraction velocity Vp is low, compared to characteristic curve Q23 in Figure 16C. Similarly, characteristic curve Q24A shows the change in damping force Df when the flow velocity is high during the compression stroke, and has a characteristic in which the damping force increases even more than characteristic curve Q24 in Figure 16C.

[0085] This shows that when the shock absorber 700 is compressed, the damping force Df increases rapidly when the shock absorber 700 is compressed to near its minimum value, regardless of the flow velocity of the hydraulic fluid. Therefore, the toughness of the shock absorber 700 can be increased when a large compressive load is applied to the shock absorber 700.

[0086] The shock absorbers 20, 200 to 700 described above can be summarized as follows.

[0087] 3 and 11 to 16. According to this embodiment, first, the shock absorber 20, 200 to 700 includes a cylindrical outer tube 30 and a cylindrical inner tube 40, at least a portion of which is fitted into the outer tube 30 so as to be relatively movable in the axial direction. The shock absorber 20, 200 to 700 further includes a partition member 121, the movement of which is restricted in the axial direction relative to the inner tube 40, which partitions a space 100, which exists between an outer peripheral surface 45 of the inner tube 40 and an inner peripheral surface 36 of the outer tube 30, into a first chamber 101 on the insertion end side of the inner tube 40 and a second chamber 102 on the opposite side in the axial direction from the first chamber 101, and a check valve 122, which is provided in the partition member 121 and allows the flow of hydraulic fluid from the first chamber 101 to the second chamber 102 and restricts the flow of hydraulic fluid from the second chamber 102 to the first chamber 101. Furthermore, the shock absorbers 20, 200 to 700 include a communication portion 46 (first communication portion 46) that connects the internal space 41 of the inner tube 40 with the second chamber 102, and a gap forming member 130, 530 that is fitted onto the inner surface 44 of the inner tube 40 and has a gap 140 that forms a flow path for the working fluid flowing between the internal space 41 of the inner tube 40 and the first chamber 101 and imparts flow resistance to the working fluid.

[0088] The gap forming member 130, 530 applies flow resistance to the hydraulic fluid that passes through the gap 140 and flows into the first chamber 101 (reservoir chamber 101) during the extension stroke and compression stroke, and also functions as a "pump" during the compression stroke. The partition member 121 functions as a piston that compresses the second chamber 102 and increases the internal pressure during the extension stroke, and has a check valve 122 that opens only during the compression stroke to allow the hydraulic fluid to flow from the first chamber 101 to the second chamber 102. Therefore, it is possible to provide an inverted shock absorber 20, 200 to 700 that can reduce costs by using a simple configuration with a small number of parts to generate damping force.

[0089] See Figures 3 and 11 to 16. Secondly, preferably, in the shock absorber 20, 200 to 700 described above, the gap forming member 130, 530 includes a cylindrical tube portion 132, 532 (first tube portion 532) that is fitted to the inner circumferential surface 44 of the inner tube 40 with a gap 140 therebetween to be able to move relatively, and a partition portion 133 that separates the interior of the tube portion 132, 532 from the internal space 41 of the inner tube 40.

[0090] In this way, the gap forming members 130, 530 have a simple configuration consisting of a cylindrical portion 132, 532 that fits with the inner peripheral surface 144 of the inner tube 40 with a gap 140 formed therebetween, and a partition portion 133 that separates the interior 132a of the cylindrical portion 132, 532 from the internal space 141 of the inner tube 40. Therefore, the gap forming members 130, 530 are easy to manufacture, and inexpensive parts can be provided.

[0091] See Figures 3 and 11 to 16. Third, preferably, the shock absorber 20, 200 to 700 described in the first and second embodiments is provided with a compression coil spring 50 that biases the outer tube 30 and the inner tube 40 in a direction separating them from each other. The compression coil spring 50 is disposed in the internal space 41 of the inner tube 40. The partition portion 133 is provided at the axial end 132c of the cylindrical portion 132, 532, and also serves as a spring bearing portion that receives one end of the compression coil spring 50. The outer tube 30 is biased by the compression coil spring 50 via the gap forming member 130, 530.

[0092] In this way, the outer tube 30 is biased by the compression coil spring 50 via the gap forming members 130, 530. The gap forming members 130, 530 are constantly pressed against the outer tube 30 by the compression coil spring 50. The compression coil spring 50 separates the outer tube 30 and the inner tube 40 from each other, allowing the gap forming members 130, 530 to be stably held on the outer tube 30. Furthermore, there is no need to fix the gap forming members 130, 530 to the outer tube 30.

[0093] See Figures 3 and 11 to 16. Fourth, preferably, in the shock absorbers 20, 200 to 700 described in the second and third aspects, the gap forming member 130, 530 has a hole 134 (second communicating portion 134) that can communicate between the interior 132a of the cylindrical portion 132 and the gap 140.

[0094] Therefore, the hydraulic fluid that has entered the interior 132a (air chamber 132a) of the cylindrical portion 132, 532 of the gap forming member 130, 530 can be discharged from the hole 134 to the gap 140. Moreover, because the flow rate of the hydraulic fluid passing through the gap 140 is relatively fast, the pressure in the gap 140 is lower than the pressure in the interior 132a of the cylindrical portion 132, 532. Therefore, the discharge effect of the hydraulic fluid that has entered the interior 132a of the cylindrical portion 132, 532 can be improved.

[0095] See Figure 16. Fifth, preferably, in the shock absorber 700 described in the first aspect, the communicating portion 46 (first communicating portion 46) is configured to penetrate between the outer peripheral surface 45 and the inner peripheral surface 44 of the inner tube 40. The axial position of the communicating portion 46 with respect to the inner tube 40 is defined as a communicating position P2. A fixed relative movement distance St2 in the axial direction of the inner tube 40 with respect to the gap forming member 130 (fixed relative movement distance St2 in the compression direction) is defined as a reference stroke St2. The communicating position P2 of the communicating portion 46 when the inner tube 40 has moved (compressed) to the reference stroke St2 is set to a position where the communicating portion 46 axially overlaps with the gap forming member 130.

[0096] Therefore, when the inner tube 40 moves to the reference stroke St2, the communication portion 46 overlaps the gap forming member 130. The communication portion 46 is set to overlap the gap forming member 130 at or near the position where the shock absorber 700 is at its minimum extension during the compression stroke. In this case, there is no outlet for the hydraulic fluid in the internal space 141 of the inner tube 40, and the hydraulic fluid cannot pass through. As a result, the reaction force can be increased near the minimum extension of the shock absorber 700. This makes it possible to increase the toughness of the shock absorber 700 when a large compressive force (external force) is input to the shock absorber 700.

[0097] See Figures 3 and 8. Sixth, in the shock absorber 20 according to the first aspect, preferably, the area A1 of the second chamber 102 is set to be larger than the area A2 of the internal space 41 of the inner tube 40 when the outer tube 30 is viewed in the axial direction.

[0098] Since A1 > A2 is set as described above, if the hydraulic fluid in the compression chamber 41 simply flows through the first communication portion 46 to the extension chamber 102 during the compression stroke shown in FIG. 10 , the flow resistance of the hydraulic fluid passing through the first communication portion 46 will result in a large damping effect during the compression stroke. In contrast, the shock absorber 20 has a tubular gap 140 in addition to the first communication portion 46. The hydraulic fluid in the compression chamber 41 flows through the tubular gap 140 to the reservoir chamber 101, and then flows from the reservoir chamber 101 to the extension chamber 102 through the check valve 122. This reduces the damping force during the compression stroke. This improves the ride comfort of the saddle-ride type vehicle.

[0099] See Figure 12. Seventh, preferably, in the shock absorber 300 according to the first aspect, when the outer tube 30 is viewed in the axial direction, the area A2 of the internal space 41 of the inner tube 40 is set to be larger than the area A1 of the second chamber 102.

[0100] Since A1<A2 is set as described above, if the hydraulic fluid in the compression chamber 41 simply flows through the first communication portion 46 to the extension chamber 102 during the compression stroke shown in FIG. 12A , the flow resistance of the hydraulic fluid passing through the first communication portion 46 would result in a large damping effect during the compression stroke. In contrast, the shock absorber 300 has a tubular gap 140 in addition to the first communication portion 46. The hydraulic fluid in the compression chamber 41 flows through the tubular gap 140 to the reservoir chamber 101, and then flows from the reservoir chamber 101 to the extension chamber 102 through the check valve 122. This reduces the damping force during the compression stroke. This improves the ride comfort of the saddle-ride type vehicle.

[0101] The shock absorbers 20, 200 to 700 according to the present invention are not limited to the above-described embodiments, as long as they exhibit the functions and effects of the present invention.

[0102] The shock absorbers 20, 200 to 700 of the present invention are suitable for application to the front fork 10 mounted on a saddle-ride type vehicle.

[0103] 20... shock absorber, 30... outer tube, 36... inner circumferential surface, 40... inner tube, 41... internal space (compression chamber), 44... inner circumferential surface, 45... outer circumferential surface, 46... communication portion (first communication portion), 50... compression coil spring, 100... space, 101... first chamber (reservoir chamber), 102... second chamber (extension chamber), 121... partition member, 122... check valve, 130... gap forming member, 131... outer circumferential surface, 132... cylindrical portion, 132a... interior, 132b... upper end, 132c... axial end portion, 133... partition portion, 134... hole portion (second communication portion), 135... hole portion (third communication portion), 140... gap, 200, 300, 400, 500... shock absorber, 530...Gap forming member, 531...Outer peripheral surface, 600, 700...Shock absorber, A1...Area of ​​second chamber, A2...Area of ​​inner space of inner tube, CL...Center line CL, P1, P2...Communication positions, St1, St2...Reference stroke (relative movement distance).

Claims

1. A shock absorber comprising: a cylindrical outer tube; a cylindrical inner tube, at least a portion of which is fitted into the outer tube so as to be relatively movable in the axial direction; a partition member, the change in relative position of which in the axial direction relative to the inner tube being restricted, which partitions the space between the outer peripheral surface of the inner tube and the inner peripheral surface of the outer tube into a first chamber on the insertion end side of the inner tube and a second chamber on the opposite side of the first chamber in the axial direction; a check valve, which is provided in the partition member and allows the flow of hydraulic fluid from the first chamber to the second chamber and restricts the flow of hydraulic fluid from the second chamber to the first chamber; a communicating part, which communicates the internal space of the inner tube with the second chamber; and a gap forming member, which is fitted into the inner peripheral surface of the inner tube and has a gap that forms a flow path for the hydraulic fluid flowing between the internal space of the inner tube and the first chamber and imparts flow resistance to the hydraulic fluid.

2. A shock absorber as described in claim 1, wherein the gap forming member comprises a cylindrical tubular portion that is fitted to the inner surface of the inner tube with the gap so as to be able to move relative to the inner surface, and a partition portion that separates the interior of the tubular portion from the internal space of the inner tube.

3. A shock absorber as described in claim 2, further comprising a compression coil spring that biases the outer tube and the inner tube in a direction separating them from each other, the compression coil spring being disposed in the internal space of the inner tube, the partition portion being provided at the axial end of the cylindrical portion and also serving as a spring receiving portion that receives one end of the compression coil spring, and the outer tube being biased against the compression coil spring via the gap forming member.

4. A shock absorber according to claim 2, wherein the gap forming member has a hole that allows the interior of the cylindrical portion to communicate with the gap.

5. A shock absorber as described in claim 1, wherein the communicating portion is configured to penetrate between the outer peripheral surface and the inner peripheral surface of the inner tube, the axial position of the communicating portion relative to the inner tube is defined as a communicating position, a fixed relative axial movement distance of the inner tube relative to the gap forming member is defined as a reference stroke, and the communicating position of the communicating portion when the inner tube has moved to the reference stroke is set at a position where the communicating portion overlaps with the gap forming member in the axial direction.

6. The shock absorber according to claim 1, wherein the area of ​​the second chamber is set larger than the area of ​​the internal space of the inner tube when the outer tube is viewed in the axial direction.

7. The shock absorber according to claim 1, wherein the area of ​​the internal space of the inner tube is set larger than the area of ​​the second chamber when the outer tube is viewed in the axial direction.

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