JP7379759B1 - hydraulic shock absorber - Google Patents

Abstract

The hydraulic shock absorber (10) includes a cylinder (16) extending from a lower end (13a) of the axle side tube (13) into the inside of the vehicle body side tube (11), and an upper end (11a) of the vehicle body side tube (11). ) into the cylinder (16), a piston (30) connected to the first rod (40), and a lower end of the cylinder (16) from the piston (30). a second rod (50) extending to the portion (16a). The inside of the cylinder (16) is divided into a first oil chamber (71) by the piston (30) and a first partition wall (80), and a second oil chamber (71) by the piston (30) and a second partition wall (90). It is divided into an oil room (72). The sealing performance of the first partition wall (80) is lower than that of the second partition wall (90).

Description

The present invention relates to a hydraulic shock absorber particularly suitable for use in a saddle-riding type vehicle in which a passenger rides astride.

2. Description of the Related Art Hydraulic shock absorbers in which a vehicle body side tube and an axle side tube are configured in a telescopic manner are used in suspension systems mounted on saddle-type vehicles such as two-wheeled vehicles and three-wheeled vehicles. For example, a front fork is a so-called cartridge type in which a cylinder (cartridge) is installed inside the axle side tube, a piston with a valve is slidably installed inside this cylinder, and a rod connected to this piston is installed on the body side tube. Hydraulic shock absorbers are also used.

With conventional cartridge-type front forks, two damping force variable devices are required to ensure both the adjustment range of the damping force on the extension side and the adjustment range of the damping force on the compression side, which increases costs. This can be a factor. Therefore, efforts have been made to develop a hydraulic shock absorber having a so-called double-rod structure, in which two rods are provided on both sides of the piston. With a double rod type hydraulic shock absorber, there is no movement of hydraulic oil due to the volume of the rod moving in and out of the cylinder. Therefore, pressure fluctuations in the hydraulic oil within the cylinder can also be suppressed. This double-rod structure hydraulic shock absorber is known, for example, from Patent Document 1.

The hydraulic shock absorber known from Patent Document 1 includes a cylinder provided inside an axle-side tube, a piston slidably provided in the cylinder, and a first rod and a second rod connected to both ends of the piston, respectively. It is said that it was done. The upper end of the cylinder is partitioned by a first partition. The lower end of the cylinder is partitioned by a second partition. The first rod extends upward from the piston, passes through the first partition wall, and is connected to the upper end of the vehicle body tube. A second rod extends downwardly from the piston and through the second partition. The cylinder has inside thereof a first oil chamber (upper chamber) partitioned by the piston and the first partition wall, and a second oil chamber (lower chamber) partitioned by the piston and the second partition wall. .

Furthermore, the space (space) defined by the outer circumferential surface of the cylinder and the inner circumferential surface of the axle-side tube can store hydraulic fluid. In this space, an air chamber is located above the level of the hydraulic oil. The air stored in this air chamber provides the air reaction force (air spring effect) of the hydraulic shock absorber.

The level of the hydraulic oil stored in the space is set higher than the first partition wall. Therefore, the outer peripheral surface of the cylinder and the upper surface of the first partition wall are immersed in hydraulic oil. This first bulkhead is equipped with a check valve. This check valve allows hydraulic oil to flow into the first oil chamber from above the first partition, but conversely prevents hydraulic oil from flowing out from the first oil chamber to above the first partition. are doing. When the hydraulic oil in the first oil chamber becomes insufficient, the check valve opens and the first oil chamber can be replenished with hydraulic oil.

Japanese Patent Application Publication No. 2010-230091

In the hydraulic shock absorber known from Patent Document 1, the height of the hydraulic oil level stored in a space (space) defined by the outer circumferential surface of the cylinder and the inner circumferential surface of the axle side tube is It is required to be set higher than the first partition wall. If the upper surface of the first partition wall is not immersed in hydraulic oil, if air enters the first oil chamber, it will cause a failure in the generation of damping force. Therefore, the oil level of the hydraulic oil stored in the space must be set to such a level that at least the upper surface of the first partition wall is immersed in the hydraulic oil. This is disadvantageous because it imposes restrictions on increasing the degree of freedom in setting the air reaction force (air spring effect) of the hydraulic shock absorber. Therefore, there is room for improvement in appropriately managing the damping force generated when the hydraulic shock absorber expands and contracts.

An object of the present invention is to provide a technology that can appropriately manage the damping force generated when the hydraulic shock absorber expands and contracts in a double rod type hydraulic shock absorber.

As a result of extensive studies, the inventors of the present invention have focused on the fact that it is sufficient to prevent the air accumulation phenomenon that occurs in the upper first oil chamber when the hydraulic shock absorber is assembled to the vehicle body. The inventors have also discovered that by removing air from the sealed portion of the first partition wall, it is possible to prevent the air accumulation phenomenon occurring in the upper first oil chamber. The present invention was completed based on these findings.

According to the present disclosure, a telescopic vehicle body-side tube and an axle-side tube are arranged on the vehicle body side and a wheel side, respectively; a cylinder extending from a lower end of the axle-side tube into the interior of the vehicle body-side tube; a first rod extending from the upper end of the vehicle body side tube into the interior of the cylinder; a piston connected to the first rod and slidable against the inner wall of the cylinder; and a lower end of the cylinder extending from the piston. a second rod extending into the cylinder; a partition wall located inside the cylinder and closer to the upper end of the vehicle body side tube than the piston, partitioning and sealing the inside of the cylinder into a first oil chamber; a first partition wall with low sealing performance; a first reservoir that is partitioned by the outer circumferential surface of the cylinder and the inner circumferential surface of the axle-side tube and capable of storing hydraulic oil; A second reservoir that is partitioned by the lower end of the cylinder and the second partition wall and can store hydraulic oil; and a communication path that communicates the first reservoir and the second reservoir. Hydraulic shock absorbers are provided.

The present disclosure can provide a technique that can appropriately manage the damping force generated when the hydraulic shock absorber expands and contracts in a double rod type hydraulic shock absorber.

FIG. 2 is a cross-sectional side view of a main part of the hydraulic shock absorber according to the embodiment. FIG. 2 is a schematic diagram of the hydraulic shock absorber shown in FIG. 1; 2 is an enlarged view of part 3 of FIG. 1. FIG. 2 is an enlarged view of part 4 of FIG. 1. FIG. FIG. 5 is a perspective view of the second partition, the coupling mechanism, and the check valve shown in FIG. 4; 2 is an enlarged view of part 6 of FIG. 1. FIG. FIG. 4 is a perspective view of the spring guide shown in FIG. 3; 2 is a damping force characteristic diagram of the hydraulic shock absorber shown in FIG. 1. FIG.

Embodiments of the present invention will be described below based on the accompanying drawings. Note that the form shown in the attached drawings is an example of the present invention, and the present invention is not limited to this form. In the explanation, "up and down" refers to the top and bottom with respect to the state in which a hydraulic shock absorber is mounted on a saddle-ride type vehicle. Further, in the figure, Up indicates the top and Dn indicates the bottom.

<Example>
A hydraulic shock absorber 10 according to an embodiment will be described with reference to FIGS. 1 to 8.

As shown in FIGS. 1 and 2, the hydraulic shock absorber 10 is used in a motorcycle, which is a type of saddle-riding vehicle (not shown) on which a rider rides astride. In the following, a motorcycle may be referred to as a "saddle-riding vehicle."

The hydraulic shock absorber 10 is of a telescopic type, and includes a cylindrical body-side tube 11 (first tube 11) that can be connected to a car body-side bracket (not shown), and a cylindrical body-side tube 11 that is connected to an axle-side bracket 12. An axle-side tube 13 (second tube 13) is provided. The axle-side bracket 12 can be connected to a wheel axle (not shown). The axle-side tube 13 is fitted so as to be movable relative to the vehicle body-side tube 11. The upper end portion 11a of the vehicle body side tube 11 is closed by, for example, a closing member 14 (cap member 14).

Referring also to FIG. 3, the lower end portion 13a of the axle-side tube 13 is fitted into and fixed to the axle-side bracket 12, and is closed by, for example, an annular closing member 15 (bottom member 15).

Here, the stroke in which the hydraulic shock absorber 10 contracts is referred to as a compression stroke, and the stroke in which the hydraulic shock absorber 10 extends is referred to as an extension stroke. In this embodiment, the hydraulic shock absorber 10 has an inverted configuration in which the axle-side tube 13 moves forward and backward relative to the vehicle-body side tube 11. However, the hydraulic shock absorber 10 includes an upright configuration in which the vehicle body side tube 11 is moved forward and backward relative to the axle side tube 13.

As shown in FIGS. 1 and 2, the hydraulic shock absorber 10 further includes a cylinder 16 extending from the lower end 13a (for example, the axle-side bracket 12) of the axle-side tube 13 into the vehicle body-side tube 11. As shown in FIG. 3, the lower end 16a of the cylinder 16 is fitted into the annular bottom member 15, extends further downward, is closed by a bottom cap 17, and is fixed to the axle side bracket 12 by the bottom cap 17. has been done.

As shown in FIG. 3, the hydraulic shock absorber 10 includes a compression coil spring 21 that biases the vehicle body side tube 11 and the axle side tube 13 in a direction to separate them from each other, and an inner peripheral surface of the coil of the compression coil spring 21. It is provided with a cylindrical spring guide 22 that guides the spring guide 21a. The compression coil spring 21 and the spring guide 22 are located between the inner peripheral surface 13b of the axle-side tube 13 and the outer peripheral surface 16b of the cylinder 16.

The spring guide 22 is a pipe-shaped member. The lower end 22a of this spring guide 22 is provided with a flange 22b that supports the lower end surface 21b of the compression coil spring 21. The flange 22b is a flat plate-shaped portion whose diameter increases from the lower end 22a of the spring guide 22. The lower end surface 22c of this flange 22b overlaps the closing member 15 and is supported by this closing member 15. As shown in FIG. 2, the upper end of the compression coil spring 21 is supported by a pipe-shaped spring receiving portion 23 extending downward from the cap member 14 of the upper end portion 11a of the vehicle body side tube 11.

As shown in FIG. 2, the hydraulic shock absorber 10 has a so-called double rod type structure, which includes two rods 40, 50 (a first rod 40 and a second rod 50) on both sides of the piston 30 in the axial direction. be. The two rods 40 and 50 are pipe-shaped members located on the center line CL of the piston 30.

As shown in FIG. 4, the piston 30 is slidable on the inner peripheral surface 16c of the cylinder 16. The piston 30 includes a piston body 31 that is slidable on the inner circumferential surface 16c of the cylinder 16, and a pipe-shaped piston shaft 32 that passes through the piston body 31 and is located on the center line CL. This piston shaft 32 is fixed to the piston body 31.

As shown in FIG. 2, the first rod 40 extends into the cylinder 16 from the upper end 11a of the vehicle body tube 11. As shown in FIG. For example, the upper end 41 of the first rod 40 is provided at the upper end 11a of the vehicle body tube 11 by being connected to a drive device 140 provided in the cap member 14. A lower end 42 of the first rod 40 is connected to an upper end 32a of the piston shaft 32 via a control valve 130. Details of the control valve 130 and the drive device 140 will be described later.

The second rod 50 extends from the piston 30 to the lower end 16a of the cylinder 16. The lower end 51 of this second rod 50 is a free end that is not fixed anywhere. The upper end 52 of the second rod 50 is connected to the lower end 32b of the piston shaft 32 by a connecting mechanism 60 (see FIG. 5) so as to be swingable relative to the center line CL of the piston 30.

As shown in FIG. 5, the connection mechanism 60 includes a connection base 61 attached to the lower end 32b of the piston shaft 32, a support part 62 removably attached to the connection base 61, and a support part 62 that is removably attached to the connection base 61. 62 is provided with a latching portion 63 for swingably latching the upper end portion 52 of the second rod 50.

The connecting base member 61 is a cylindrical member with a bottom that is open toward the second rod 50, and has a bottom portion 61a attached to the lower end portion 32b of the piston shaft 32 by a connecting member 64 such as a nut.

The support portion 62 is a cylindrical member, and is attached to the inner circumferential surface of the cylindrical portion 61a of the connection base material 61 by fastening such as screwing. An annular swing support portion 62b having a smaller diameter than the inner circumferential surface 62a is integrally formed on the inner circumferential surface 62a of the support portion 62.

The latching portion 63 protrudes in the radial direction from the outer circumferential surface 52a of the upper end portion 52 of the second rod 50 over the entire circumference of the outer circumferential surface 52a. For example, the latching portion 63 is constituted by a retaining ring fitted into the outer circumferential surface 52a of the upper end portion 52 of the second rod 50.

By latching the latching portion 63 provided on the second rod 50 to the swing support portion 62b, the upper end surface 53 of the second rod 50 comes into contact with the axial end surface 64a of the coupling member 64, or Close to each other. Therefore, the upper end portion 52 of the second rod 50 can swing in all directions with respect to the center line CL of the piston 30 by at least one of the end surface 64a of the coupling member 64 and the swing support portion 62b of the support portion 62. supported, so-called floating supported. In this way, the second rod 50 is connected to the piston 30 so as to be swingable relative to the center line CL of the piston 30.

As shown in FIG. 2, the inside of the cylinder 16 is divided by the piston 30 into two oil chambers 71 and 72 (an upper first oil chamber 71 and a lower second oil chamber 72). Specifically, the cylinder 16 includes a first partition wall 80 and a second partition wall 90 inside. The first partition wall 80 is located closer to the upper end of the vehicle body tube 11 than the piston 30 is. The second partition wall 90 is located closer to the lower end of the axle-side tube 13 than the piston 30 is. The piston 30 and the first partition wall 80 partition and seal the inside of the cylinder 16 into a first oil chamber 71. The piston 30 and the second partition wall 90 partition and seal the inside of the cylinder 16 into a second oil chamber 72.

As shown in FIG. 4, the lower end 42 of the first rod 40, the upper end 32a of the piston shaft 32, and the control valve 130 are located in the first oil chamber 71. The upper end 52 of the second rod 50, the lower end 32b of the piston shaft 32, and the coupling mechanism 60 are located in the second oil chamber 72.

First, the second partition wall 90 will be explained. As shown in FIGS. 3 and 4, the second partition 90 is supported by a partition supporting portion 91. As shown in FIGS. This partition support portion 91 is constituted by a pipe extending from the lower end portion 16a of the cylinder 16 into the interior of the cylinder 16. The lower end portion 91a of the partition support portion 91 is closed by a bottom cap 17, and is fixed to the axle-side bracket 12 by the bottom cap 17.

As shown in FIG. 5, the second partition 90 is a cylindrical member fixed to the upper end 91b of the partition support 91. As shown in FIG. The upper end portion 52 of the second rod 50 penetrates the inside of the second partition wall 90 and enters the second oil chamber 72 . Since the second partition wall 90 supports the second rod 50 so as to be movable in the axial direction, it can be considered that the second partition wall 90 is constituted by a rod guide. That is, the second partition wall 90 is constituted by a second rod guide that supports the second rod 50. The second partition wall 90 includes a bush 92 (bearing 92) that slidably supports the second rod 50 in the axial direction, and two second oil chambers that partition and seal the inside of the cylinder 16 into a second oil chamber 72. Seal members 93 and 94 (inner seal member 93 and outer seal member 94) are provided.

The internal seal member 93 is a rubber member that fluid-tightly seals between the outer circumferential surface 52a of the upper end portion 52 of the second rod 50 and the inner circumferential surface 90a of the second partition wall 90, and is formed of, for example, an oil seal. has been done. The external seal member 94 is a rubber member that provides a liquid-tight seal between the inner circumferential surface 16c of the cylinder 16 and the outer circumferential surface 90b of the second partition wall 90, and is formed of, for example, an O-ring. Since sealing is performed by the second seal members 93 and 94, the sealing performance of the second partition wall 90 is high.

Next, the first partition wall 80 will be explained. As shown in FIG. 6, the first partition wall 80 is fixed to the upper end portion 16d of the cylinder 16. The first rod 40 penetrates the inside of the first partition 80. Since the first partition wall 80 supports the first rod 40 so as to be movable in the axial direction, it can be considered that the first partition wall 80 is constituted by a rod guide. That is, the first partition wall 80 is constituted by a first rod guide that supports the first rod 40.

The first partition wall 80 includes a bush 83 (bearing 83) that slidably supports the first rod 40 in the axial direction. Furthermore, the first partition 80 includes a bottomed cylindrical partition main body 81 fixed to the cylinder 16, a lid 82 that closes the open end of the partition main body 81, and a bush 83 that is located inside the partition main body 81 and holds a bush 83. An annular holding portion 84 is provided. The bottom plate 81a and the lid 82 of the partition main body 81 have holes 81b and 82a that pass through the first rod 40.

The outer peripheral surface 81c of the partition main body 81 and the lid 82 are fitted into the inner peripheral surface 16c of the cylinder 16. There is only a small gap C1 between the outer circumferential surface 81c of the partition main body 81 and the inner circumferential surface 16c of the cylinder 16, and it is not sealed by a sealing member. The size δ1 of the gap C1 between the outer circumferential surface 81c of the partition main body 81 and the inner circumferential surface 16c of the cylinder 16 is set, for example, as follows. Depending on the viscosity of the hydraulic oil accumulated in the first oil chamber 71, the gap is set to such an extent that this hydraulic oil does not flow out from the gap C1 or does not affect the generation of damping force by the hydraulic oil in the first oil chamber 71. It is preferable that the magnitude δ1 of C1 is set.

The gap C2 between the outer circumferential surface 43 of the first rod 40 and the inner circumferential surface 83a of the bush 83 is set to a minute size δ2 that allows the first rod 40 to slide smoothly relative to the bush 83. It is preferable.

The bush 83 is fitted into the inner peripheral surface 84a of the holding portion 84. The outer circumferential surface 84b of the holding portion 84 is supported by the inner circumferential surface 81d of the partition main body 81 via an annular elastic body 85 (for example, an O-ring 85) made of an elastic material. The elastic body 85 is fitted into the inner peripheral surface 84a of the holding portion 84. The inner circumferential surface 81d of the partition main body 81 supports the outer circumferential surface of the elastic body 85 so as to limit movement and elastic deformation of the elastic body 85 in a direction intersecting the center line CL. By using the elastic body 85, the outer circumferential surface 84b of the holding portion 84 is supported in a manner that it does not directly contact the inner circumferential surface 81d of the partition main body 81, that is, it is supported in a so-called floating manner. The elastic body 85 seals between the inner circumferential surface 81 d of the partition main body 81 and the outer circumferential surface 84 b of the holding portion 84 .

As is clear from the above description, the sealing performance of the first partition wall 80 is set lower than that of the second partition wall 90. Note that the seal structures of the first partition wall 80 and the second partition wall 90 are not limited to the above configuration, and the sealing performance of the first partition wall 80 is set lower than that of the second partition wall 90. Bye.

As shown in FIG. 3, the hydraulic shock absorber 10 further includes two reservoirs 101, 102 (a first reservoir 101 and a second reservoir 102) capable of storing hydraulic oil, and a first reservoir 101 and a second reservoir. 102 is provided. The first reservoir 101 is defined by an inner circumferential surface 13b of the axle-side tube 13 and an outer circumferential surface 16b of the cylinder 16. The second reservoir 102 is defined inside the cylinder 16 by the lower end 16a of the cylinder 16 and a second partition wall 90 (see FIG. 4). The communication path 103 is constituted by a through hole provided in the cylinder 16. The communication path 103 may be appropriately referred to as the "first through hole 103."

As shown in FIGS. 3 and 7, the lower end surface 22c of the flange 22b of the spring guide 22 can guide the hydraulic oil accumulated in the first reservoir 101 to the first through hole 103 (communication path 103). It has at least one groove 22d. This groove 22d intersects with the center line CL of the spring guide 22 and penetrates through the flange 22b in the radial direction.

As shown in FIG. 7, the closing member 15, on which the lower end surface 22c of the flange 22b overlaps, has a guide recess 15a so that the hydraulic oil flowing from the groove 22d can be guided to the first through hole 103. It is preferable to have. The shape of the guide recess 15a is, for example, a female taper that tapers from the lower end surface 22c side of the flange 22b toward the opposite side along the center line CL.

As shown in FIG. 3, the hydraulic oil stored in the first reservoir 101 is supplied to the groove 22d of the spring guide 22, the first through hole 103, and the second through hole formed in the lower end 91a of the partition support 91. It flows into the second reservoir 102 through the hole 91c. The hydraulic oil accumulated in the second reservoir 102 can flow into the second rod 50 from the opening 54 at the lower end.

As shown in FIGS. 2 and 5, the second rod 50 is equipped with a check valve 105 inside. Further, the second rod 50 has an oil inlet/outlet 55 on the upper end surface 53 side (piston 30 side) than the check valve 105 position. The oil inlet/outlet 55 penetrates the second rod 50 in the radial direction and communicates with the second oil chamber 72 . The check valve 105 allows hydraulic oil to flow from the second reservoir 102 to the second oil chamber 72 in response to the differential pressure between the second oil chamber 72 and the second reservoir 102, and prevents flow in the opposite direction. The configuration is as follows. For example, it is possible to open in response to the differential pressure between the second oil chamber 72 and the second reservoir 102 that occurs when the pressure of the hydraulic oil in the second oil chamber 72 decreases.

Next, the flow of hydraulic oil in the hydraulic shock absorber 10 will be described with reference to FIG. 2. The piston 30 (piston main body 31) includes a growth side check valve 111, a growth side throttle flow path 112, a pressure side check valve 113, and a pressure side throttle flow path 114. In the extension stroke of the hydraulic shock absorber 10, the hydraulic oil flowing from the first oil chamber 71 to the second oil chamber 72 passes through the expansion side check valve 111 and the expansion side throttle channel 112, so that the expansion side throttle channel 112 is damped. It is possible to generate force. During the compression stroke of the hydraulic shock absorber 10, the hydraulic oil flowing from the second oil chamber 72 to the first oil chamber 71 passes through the pressure side check valve 113 and the pressure side throttle channel 114, so that the pressure side throttle channel 114 generates a damping force. It is possible to do so.

When the hydraulic shock absorber 10 is in its extension stroke (when the cylinder 16 extends in the direction of the arrow Re relative to the piston 30), the volume of the upper first oil chamber 71 decreases, and the volume of the lower second oil chamber 72 decreases. increases. The pressure in the first oil chamber 71 is higher than the pressure in the second oil chamber 72. A portion of the surplus hydraulic oil in the first oil chamber 71 passes through the expansion side check valve 111 and the expansion side throttle channel 112 and flows out to the second oil chamber 72 . At this time, a damping effect is generated by the growth-side throttle channel 112. Furthermore, a portion of the surplus hydraulic oil in the first oil chamber 71 flows out into the second oil chamber 72 through a bypass passage 120 and a control valve 130, which will be described later. The control valve 130 applies flow path resistance to the hydraulic oil passing through the bypass path 120, thereby producing a damping effect.

When the hydraulic shock absorber 10 is in the compression stroke (when the cylinder 16 contracts relative to the piston 30 in the direction of arrow Rc), the volume of the upper first oil chamber 71 increases, and the volume of the lower second oil chamber 72 increases. decreases. The pressure in the second oil chamber 72 is higher than the pressure in the first oil chamber 71. A portion of the surplus hydraulic oil in the second oil chamber 72 passes through the pressure side check valve 113 and the pressure side throttle channel 114 and flows out into the first oil chamber 71 . At this time, a damping effect is generated by the pressure side throttle channel 114. Further, a portion of the excess hydraulic oil in the second oil chamber 72 flows out into the first oil chamber 71 through the bypass path 120 and the control valve 130. The control valve 130 applies flow path resistance to the hydraulic oil passing through the bypass path 120, thereby producing a damping effect.

The hydraulic shock absorber 10 includes a bypass passage 120 that bypasses the piston 30 and communicates the first oil chamber 71 and the second oil chamber 72, and provides and provides flow resistance to the hydraulic oil flowing through the bypass passage 120. A control valve 130 that can adjust flow path resistance is included. This control valve 130 is arranged in either the first oil chamber 71 or the second oil chamber 72, for example, in the first oil chamber 71.

The bypass passage 120 is an oil passage from the oil inlet/outlet 55 of the second rod 50 to the oil inlet/outlet 132a of the control valve 130 via the inside of the pipe-shaped piston shaft 32 and the inside of the control valve 130.

As shown in FIG. 4, the control valve 130 has the function of a variable throttle valve, and is driven by a drive device 140 (see FIG. 2). This drive device 140 is constituted by an actuator or a manual operation mechanism. The drive device 140 includes an actuation rod 141 (valve rod 141) that drives and controls the control valve 130. The actuating rod 141 passes through the inside of the first rod 40 so as to be movable back and forth in the axial direction. The opening degree of the control valve 130 can be adjusted according to the advancing distance of the actuating rod 141.

Control valve 130 is removably attached to lower end 42 of first rod 40 . The control valve 130 includes a valve body holder 131 attached to the lower end portion 42 of the first rod 40, and a bottomed cylindrical valve housing 132 provided on the lower surface of the valve body holder 131. A valve housing portion 133 is defined inside by the valve body holder 131 and the valve housing 132 . The valve body holder 131 holds a valve body 134 located on the center line CL of the first rod 40 (on the center line CL of the piston 30). This valve body 134 is movable along the center line CL by being pushed by the actuation rod 141 of the drive device 140.

The valve housing 132 has at least one oil inlet/outlet 132a that allows the valve housing portion 133 and the first oil chamber 71 to communicate with each other. A bottom plate 132b of the valve housing 132 is connected to an upper end 32a of the piston shaft 32. The upper end 32a of the piston shaft 32 includes a valve seat 135 facing the valve body 134.

The opening degree of the control valve 130 changes according to the amount of movement of the valve body 134 with respect to the valve seat 135. By adjusting the amount of movement of the valve body 134 using the drive device 140 (see FIG. 2), the amount of damping force generated by the control valve 130 can be adjusted. The valve body 134 is urged by a coil spring 136 in a direction away from the valve seat 135.

Next, the damping force characteristics of the hydraulic shock absorber 10 will be explained with reference to FIGS. 2 and 8. In FIG. 8, the horizontal axis represents the moving speed Vp of the piston 30, and the vertical axis represents the damping force Df generated by the hydraulic shock absorber 10, and the adjustment range Vw1 of the damping force Df due to the provision of the bypass passage 120 and the control valve 130 is shown. , Vw2.

A characteristic line Df11 indicates the minimum damping force characteristic of the hydraulic shock absorber 10 in the case of an extension stroke (extension side). A characteristic line Df12 indicates the maximum damping force characteristic of the hydraulic shock absorber 10 in the case of an extension stroke. In the case of the extension stroke, the maximum adjustment range of the damping force Df is Vw1.

A characteristic line Df21 indicates the minimum damping force characteristic of the hydraulic shock absorber 10 in the case of a compression stroke (retraction side). A characteristic line Df22 indicates the maximum damping force characteristic of the hydraulic shock absorber 10 in the case of a compression stroke. In the case of the compression stroke, the maximum adjustment range of the damping force Df is Vw2.

Although the hydraulic shock absorber 10 of this embodiment has a single piston 30, by combining the bypass passage 120 and the control valve 130, the maximum adjustment range Vw1 of the damping force Df in the extension stroke and the maximum adjustment range Vw1 in the compression stroke can be adjusted. The maximum adjustment range Vw2 of the damping force Df can be set to be the same as the maximum adjustment range Vw2 of the damping force Df. In other words, the hydraulic shock absorber 10 of this embodiment can secure both the adjustment range (adjustment range) of the damping force on the extension side and the adjustment range of the damping force on the compression side. Furthermore, only one control valve 130 (variable damping force device 130) is required. For example, the characteristic line Df21 of the minimum damping force characteristic of the compression stroke can be set to be the same as the characteristic line Df11 of the minimum damping force characteristic of the extension stroke. Furthermore, the characteristic line Df22 of the maximum damping force characteristic of the compression stroke can be set to be the same as the characteristic line Df12 of the maximum damping force characteristic of the extension stroke.

The hydraulic shock absorber 10 described above is summarized as follows.

See FIG. 2. According to this embodiment, firstly, the hydraulic shock absorber 10 includes a telescopic vehicle body side tube 11 and an axle side tube 13 disposed on the vehicle body side and the wheel side, respectively, and a lower end portion 13a of the axle side tube 13. The cylinder 16 extends from the inside of the vehicle body side tube 11.

Further, the hydraulic shock absorber 10 includes a first rod 40 extending from the upper end 11a of the vehicle body side tube 11 into the inside of the cylinder 16, and a first rod 40 that is connected to the first rod 40 and slides against the inner circumferential surface 16c of the cylinder 16. It includes a movable piston 30 and a second rod 50 extending from the piston 30 to the lower end 16a of the cylinder 16.

Furthermore, the hydraulic shock absorber 10 is located inside the cylinder 16 and on the lower end side of the axle-side tube 13 than the piston 30, and has a second oil chamber 72 that partitions the inside of the cylinder 16 into a second oil chamber 72 for sealing. A partition wall 90 is located inside the cylinder 16 and closer to the upper end of the vehicle body side tube 11 than the piston 30, and partitions and seals the inside of the cylinder 16 into a first oil chamber 71. The first partition wall 80 has a lower sealing property than the first partition wall 80.

Further, the hydraulic shock absorber 10 is partitioned by the outer circumferential surface 16b of the cylinder 16 and the inner circumferential surface 13b of the axle side tube 13, and includes a first reservoir 101 that can store hydraulic oil, and a first reservoir 101 inside the cylinder 16. A second reservoir 102 that is partitioned by the lower end 16a of the cylinder 16 and the second partition wall 90 and can store hydraulic oil, and a communication passage 103 that communicates the first reservoir 101 and the second reservoir 102. , contains.

As described above, the hydraulic shock absorber 10 has a so-called double rod type structure, which includes two rods 40 and 50 on both sides of the piston 30 in the axial direction. The inside of the cylinder 16 is partitioned into a first oil chamber 71 by the piston 30 and an upper first partition 80, and partitioned into a second oil chamber 72 by the piston 30 and a second partition 90. When the hydraulic shock absorber 10 is attached to a vehicle body (not shown), the first partition wall 80 is located above the second partition wall 90. The sealing performance (sealing performance) of the first partition wall 80 is set lower than that of the second partition wall 90. The air (including air bubbles) that has entered the second oil chamber 72 is sent from the second oil chamber 72 to the first oil chamber 71 together with the hydraulic oil by the piston 30 when the hydraulic shock absorber 10 performs a compression operation. The air that has entered the first oil chamber 71 is discharged outward (to the first reservoir 101) from the first partition wall 80, which has poor sealing performance, when the hydraulic shock absorber 10 performs an extension operation.

For example, as shown in FIG. 6, the seal portion of the first partition 80 is formed between a minute gap C1 between the outer circumferential surface 81c of the partition main body 81 and the inner circumferential surface 16c of the cylinder 16, and the outer circumference of the first rod 40. It is constituted by a minute gap C2 between the surface 43 and the inner circumferential surface 83a of the bush 83. The sizes δ1 and δ2 of each of the gaps C1 and C2 are extremely small. The sealed portions (the gaps C1 and C2) of the first partition wall 80 can function to bleed air. Therefore, it is possible to prevent the air accumulation phenomenon occurring in the first oil chamber 71 and the second oil chamber 72 shown in FIG. The chamber 71 and the second oil chamber 72 can be filled with hydraulic oil. The damping force generated when the hydraulic shock absorber 10 extends is not affected by the height of the oil level of the hydraulic oil stored in the first reservoir 101. In other words, it is possible to increase the degree of freedom in setting the amount of hydraulic oil stored in the first oil chamber 71, so that the damping force generated when the hydraulic shock absorber 10 extends can be appropriately managed. . Therefore, in the double rod type hydraulic shock absorber 10, the damping force generated when the hydraulic shock absorber 10 expands and contracts can be appropriately managed. Furthermore, since the sealing performance of the first partition wall 80 is simply set lower than the sealing performance of the second partition wall 90, there is no need to add a separate structure for removing air from the first oil chamber 71.

Therefore, in the double-rod type hydraulic shock absorber 10 that includes two rods 40 and 50 on both sides of the piston 30 in the axial direction, the damping force generated when the hydraulic shock absorber 10 expands and contracts can be appropriately controlled. can be managed.

In addition, since there is no restriction on the height of the hydraulic oil level stored in the first reservoir 101, the amount of air stored in the air chamber above the oil level can be appropriately set. By setting the amount of air, the degree of freedom in setting the air reaction force (air spring effect) of the hydraulic shock absorber 10 can be increased.

See FIG. 6. Secondly, preferably, in the hydraulic shock absorber 10 described in the first aspect, the first partition wall 80 is constituted by a first rod guide that supports the first rod 40. The first rod guide 80 (first partition wall 80) includes a first seal portion that partitions and seals the inside of the cylinder 16 into a first oil chamber 71. For example, the seal portion of the first partition 80 is formed by a gap C1 between the outer circumferential surface 81c of the partition main body 81 and the inner circumferential surface 16c of the cylinder 16, and between the outer circumferential surface 43 of the first rod 40 and the inner circumferential surface 83a of the bush 83. and a gap C2 between the two.

The first partition wall 80 can be sealed by the first seal portion provided in the first rod guide 80 (first partition wall 80). Therefore, there is no need to provide a separate sealing member for partitioning and sealing the inside of the cylinder 16 into the first oil chamber 71.

See FIG. 5. Thirdly, preferably, in the hydraulic shock absorber 10 described in the first to second aspects, the second partition wall 90 is constituted by a second rod guide that supports the second rod 50. The second rod guide 90 (second partition wall 90) includes second seal members 93 and 94 that partition and seal the inside of the cylinder 16 into a second oil chamber 72.

The second partition wall 90 can be sealed by the second seal members 93 and 94 provided in the second rod guide 90 (second partition wall 90). Therefore, there is no need to provide a separate seal member for partitioning and sealing the inside of the cylinder 16 into the second oil chamber 72.

See FIG. 5. Fourthly, preferably, in the hydraulic shock absorber 10 described in any one of the first to third aspects, the second rod 50 is constituted by a pipe. A check valve 105 is provided inside this pipe 50 (second rod 50). This check valve 105 is configured to allow hydraulic oil to flow from the second reservoir 102 to the second oil chamber 72 in response to the differential pressure between the second oil chamber 72 and the second reservoir 102 .

By discharging air from the first oil chamber 71 and the second oil chamber 72, the amount of hydraulic oil stored inside each oil chamber 71, 72 decreases. However, the check valve 105 opens in response to the differential pressure between the second oil chamber 72 and the second reservoir 102 that occurs when the hydraulic shock absorber 10 extends. Therefore, the decrease in the hydraulic oil stored in the second oil chamber 72 can be quickly replenished from the second reservoir 102 to the second oil chamber 72.

See FIG. 5. Fifth, preferably, in the hydraulic shock absorber 10 described in any one of the first to fourth aspects, the second rod 50 is connected to the piston 30 so as to be swingable relative to the center line CL of the piston 30. That is, the second rod 50 is connected to the piston 30 by the connection mechanism 60.

As described above, since the second rod 50 has a structure that can swing with respect to the center line CL of the piston 30 (so-called floating support structure), it is possible to control the misalignment, parallelism accuracy, and inclination with respect to the center line CL of the piston 30. It is possible to absorb Therefore, fitting tolerances of the second rod 50 to the piston 30 and the second partition wall 90 can be relaxed, and frictional resistance can be reduced.

Please refer to FIGS. 2 and 5. Sixthly, preferably, the hydraulic shock absorber 10 according to any one of the first to fifth aspects includes a bypass passage 120 that communicates the first oil chamber 71 and the second oil chamber 72, and an operation that flows through the bypass passage 120. It includes a control valve 130 that applies flow path resistance to the oil and is capable of adjusting the applied flow path resistance.

Therefore, the control valve 130 applies flow resistance to the hydraulic oil flowing from the first oil chamber 71 to the second oil chamber 72 via the bypass path 120, and also provides flow resistance to the hydraulic oil flowing from the second oil chamber 72 to the second oil chamber 72 via the bypass path 120. It is possible to impart flow path resistance to the hydraulic oil flowing into the first oil chamber 71. Therefore, both the damping force generated when the hydraulic shock absorber 10 performs an expansion operation and the damping force generated when the hydraulic shock absorber 10 performs a compression operation can be adjusted within a sufficient range by one control valve 130. It is adjustable.

See FIG. 2. Seventhly, preferably in the hydraulic shock absorber 10 described in any one of the first to sixth aspects, the communication passage 103 is constituted by a through hole provided in the cylinder 16.

The cylinder 16 is a main structure that constitutes the hydraulic shock absorber 10 together with the vehicle body side tube 11 and the axle side tube 13. This cylinder 16 is effectively utilized to provide a through hole 103 (first through hole 103) that communicates the first reservoir 101 and the second reservoir 102. This through hole 103 can provide a communication path with a simple configuration.

See FIG. 3. Eighthly, the hydraulic shock absorber 10 according to the seventh aspect preferably includes a compression coil spring 21 that urges the vehicle body side tube 11 and the axle side tube 13 in a direction to separate them from each other; A cylindrical spring guide 22 that guides the inner circumferential surface 21b of the coil is provided. The compression coil spring 21 and the spring guide 22 are located between the outer peripheral surface 16b of the cylinder 16 and the inner peripheral surface 13b of the axle-side tube 13. The lower end 22a of the spring guide 22 includes a flange 22b that supports the lower end surface 21b of the compression coil spring 21. The lower end surface 22c of this flange 22b has a groove 22d that can guide the hydraulic oil accumulated in the first reservoir 101 to the through hole 103.

In this way, the groove 22d is provided in the lower end surface 22c of the flange 22b of the spring guide 22, which supports the lower end surface 21b of the compression coil spring 21. This groove 22d allows the hydraulic oil accumulated in the first reservoir 101 to be guided to the through hole 103. The spring guide 22 is effectively utilized to guide the hydraulic oil accumulated in the first reservoir 101 to the second reservoir 102 via the through hole 103. Therefore, the degree of freedom in arranging the spring guide 22 can be increased.

Note that the hydraulic shock absorber 10 according to the present invention is not limited to the above-mentioned embodiments as long as it achieves the functions and effects of the present invention. For example, the control valve 130 may have any configuration as long as it imparts flow resistance to the hydraulic oil passing through the bypass passage 120.

The hydraulic shock absorber 10 of the present invention is suitable for application to a front fork mounted on a saddle type vehicle.

10...Hydraulic shock absorber, 11...Vehicle side tube, 11a...Upper end, 13...Axle side tube, 13a...Lower end, 13b...Inner circumferential surface, 16...Cylinder, 16a...Lower end, 16b...Outer circumferential surface, 16c ...inner circumferential surface, 21...compression coil spring, 21a...inner circumferential surface of coil, 22...spring guide, 22a...lower end, 22b...flange, 22c...lower end surface of flange, 22d...groove, 30...piston, 40...th 1 rod, 50... Second rod, 71... First oil chamber, 72... Second oil chamber, 80... First bulkhead (first rod guide), 90... Second bulkhead (second rod guide), 93, 94 ...Second seal member, 101...First reservoir, 102...Second reservoir, 103...Communication path (through hole), 105...Check valve, 120...Bypass path, 130...Control valve, CL...Center line of piston.

Claims (8)

a telescopic body side tube and an axle side tube arranged on the vehicle body side and the wheel side, respectively;
a cylinder extending from the lower end of the axle side tube into the vehicle body side tube;
a first rod extending from the upper end of the vehicle body side tube into the interior of the cylinder;
a piston connected to the first rod and slidable against the inner wall of the cylinder;
a second rod extending from the piston to a lower end of the cylinder;
a second partition wall located inside the cylinder and closer to the lower end of the axle side tube than the piston, partitioning and sealing the inside of the cylinder into a second oil chamber;
A first oil chamber is located inside the cylinder and closer to the upper end of the vehicle body side tube than the piston, and seals the inside of the cylinder by partitioning the inside of the cylinder into a first oil chamber, which has better sealing performance than the second partition wall. a low first bulkhead;
a first reservoir that is defined by an outer circumferential surface of the cylinder and an inner circumferential surface of the axle-side tube and is capable of storing hydraulic oil;
a second reservoir defined inside the cylinder by the lower end of the cylinder and the second partition wall and capable of storing hydraulic oil;
a communication path that communicates the first reservoir and the second reservoir;
Contains hydraulic shock absorber. The first partition wall is configured by a first rod guide that supports the first rod,
The hydraulic shock absorber according to claim 1, wherein the first rod guide includes a first seal portion that partitions and seals the inside of the cylinder into the first oil chamber. The second partition wall is configured by a second rod guide that supports the second rod,
The hydraulic shock absorber according to claim 1, wherein the second rod guide includes a second seal member that partitions and seals the inside of the cylinder into the second oil chamber. The second rod is constituted by a pipe,
A check valve is provided inside the pipe to allow hydraulic oil to flow from the second reservoir to the second oil chamber in response to a differential pressure between the second oil chamber and the second reservoir. The hydraulic shock absorber according to claim 1, wherein: The hydraulic shock absorber according to claim 1, wherein the second rod is connected to the piston so as to be swingable about the center line of the piston. A bypass passage that communicates the first oil chamber and the second oil chamber; and a control valve that applies passage resistance to the hydraulic oil flowing through the bypass passage and that is capable of adjusting the applied passage resistance. The hydraulic shock absorber of claim 1, comprising: The hydraulic shock absorber according to claim 1, wherein the communication path is constituted by a through hole provided in the cylinder. further comprising: a compression coil spring that urges the vehicle body side tube and the axle side tube in a direction to separate them from each other; and a cylindrical spring guide that guides an inner circumferential surface of a coil of the compression coil spring;
The compression coil spring and the spring guide are located between the outer peripheral surface of the cylinder and the inner peripheral surface of the axle side tube,
The lower end of the spring guide includes a flange that supports the lower end surface of the compression coil spring,
8. The hydraulic shock absorber according to claim 7, wherein the lower end surface of the flange has a groove capable of guiding hydraulic oil accumulated in the first reservoir to the through hole.

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