Suspension system

Abstract

To provide a suspension device capable of adjusting an extension side attenuation force and adjusting a contraction side attenuation force at an upper end side of a front fork.SOLUTION: A suspension device S comprises a first front fork F1x and a second front fork F2y. The first front fork F1x has an extension side adjustment section 22x capable of adjusting resistance to be applied to a flow of a liquid passing through an extension side attenuation force adjustment passage 20x by an extension side attenuation force adjustment valve 21x, in a first cap 5x closing an upper end of a first vehicle body side tube 3x. The second front fork F2y has a contraction side adjustment section 25y capable of adjusting resistance to be applied to a flow of a liquid passing through a contraction side attenuation force adjustment passage 23y by a contraction side attenuation force adjustment valve 24y, in a second cap 5y closing an upper end of a second vehicle body side tube 3y.SELECTED DRAWING: Figure 3

Description

[[TECHNICAL FIELD]]

[0001] The present invention relates to a suspension device. [[BACKGROUND ART]]

[0002] Conventionally, a suspension device interposed between a vehicle body and a front wheel of a straddle-type vehicle includes a pair of left and right front forks, and a damper is built in each front fork.

[0003] More specifically, each front fork includes, for example: a fork main body including a vehicle body-side tube, an axle-side tube that is relatively movable in the axial direction with respect to the vehicle body-side tube, a cap that closes the upper end of the vehicle body-side tube, and an axle bracket that closes the lower end of the axle-side tube and holds the axle of the front wheel; and a damper accommodated in the fork main body.

[0004] The damper further includes: a cylinder whose lower end is fixed to the axle bracket; a piston rod whose upper end is connected to the cap and inserted into the cylinder; a piston that is attached to the distal end of the piston rod, slidably inserted into the cylinder, and divides the interior of the cylinder into an extension-side chamber and a compression-side chamber; a valve disc that is inserted into a lower side of the cylinder and partitions between the compression-side chamber and a chamber that communicates with a reservoir outside the cylinder via a hole provided in the cylinder; an extension-side port and a compression-side port provided in the piston; an extension-side leaf valve that opens and closes the extension-side port to apply resistance to the flow of liquid from the extension-side chamber toward the compression-side chamber; a compression-side check valve that opens and closes the compression-side port and allows only the flow of liquid from the compression-side chamber toward the extension-side chamber; a compression-side damping port and a suction port provided in the valve disc; a compression-side leaf valve that opens and closes the compression-side damping port to apply resistance to the flow of liquid from the compression-side chamber toward the reservoir; and an extension-side check valve that opens and closes the suction port and allows only the flow of liquid from the reservoir toward the compression-side chamber.

[0005] In the suspension system, in order to allow adjustment of the damping force generated by the dampers in the left and right front forks, the damper, in addition to the above configuration, includes an extension damping force adjustment passage that bypasses the extension port on the piston rod and connects the extension chamber and the compression chamber, an extension needle valve provided in the middle of the extension damping force adjustment passage, a compression damping force adjustment passage provided on the axle bracket and connecting the compression chamber and the reservoir, and a compression needle valve provided in the middle of the compression damping force adjustment passage. In the suspension system configured in this way, the flow area of ​​the extension needle valve is adjusted by operating the extension adjuster provided on the cap of the fork body. By adjusting The extension damping force during damper extension can be adjusted, and the flow area of ​​the compression needle valve can be adjusted by operating the compression adjuster provided on the axle bracket. By adjusting The compression damping force during damper compression can be adjusted (see, for example, Patent Document 1 or 2). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 11-201214 [Patent Document 2] Japanese Utility Model Publication No. 6-56532 [Overview of the project] [Problems that the invention aims to solve]

[0007] In conventional suspension systems, the rebound and compression damping forces of the dampers in each front fork can be adjusted independently. However, because the compression adjuster is located on the axle bracket at the lower end of the front fork, the user has to dismount from the vehicle, crouch down, and operate the compression adjuster to adjust the compression damping force. Thus, adjusting the compression damping force in conventional suspension systems is a cumbersome process, and there is a demand for a suspension system that allows for the adjustment of both the rebound and compression damping forces from the upper end of the front fork.

[0008] Furthermore, when considering the adjustment of compression damping force using an actuator, conventional suspension systems would require the actuator to be positioned close to the ground, making them unsuitable for actuator installation.

[0009] Therefore, the present invention aims to provide a suspension system that allows adjustment of both the extension damping force and the compression damping force at the upper end of the front fork. [Means for solving the problem]

[0010] To solve the aforementioned problems, the suspension device of the present invention comprises a first front fork and a second front fork that suspend the front wheel of a saddle-type vehicle to the vehicle body, the first front fork has a first vehicle body side tube, a first axle side tube that is movable axially relative to the first vehicle body side tube, a first cap that closes the upper end of the first vehicle body side tube, and a first axle bracket that closes the lower end of the first axle side tube and holds the axle of the front wheel, and a first fork body that is extendable and retractable, a first cylinder connected to the first axle bracket, and inside the first cylinder The first front fork includes a first piston rod inserted axially movably and having its upper end connected to a first cap, and a first piston connected to the first piston rod and inserted into the first cylinder, dividing the inside of the first cylinder into a first extension chamber and a first compression chamber, and a first damper that expands and contracts in accordance with the expansion and contraction of the first fork body and generates a damping force that hinders the expansion and contraction of the first fork body, and a first reservoir that stores liquid in the space between the first fork body and the first damper, and the second front fork includes a second vehicle side tube and a second vehicle side tube A second fork body that is extendable and retractable, having a second axle-side tube that is movable in the axial direction, a second cap that closes the upper end of the second body-side tube, and a second axle bracket that closes the lower end of the second axle-side tube and holds the front wheel axle, a second cylinder connected to the second axle bracket, a second piston rod that is inserted into the second cylinder so as to be movable in the axial direction and whose upper end is connected to the second cap, and a second piston rod that is connected to the second piston rod and inserted into the second cylinder and divides the inside of the second cylinder into a second extension chamber and a second compression chamber. The first damper has a second piston and a second damper that expands and contracts in accordance with the expansion and contraction of the second fork body and generates a damping force that hinders the expansion and contraction of the second fork body, and a second reservoir that stores liquid in the space between the second fork body and the second damper, the first damper has an expansion damping force adjustment passage that connects the first expansion chamber and the first compression chamber, an expansion damping force adjustment valve provided in the middle of the expansion damping force adjustment passage and an expansion adjustment part provided on the first cap that can adjust the resistance that the expansion damping force adjustment valve imparts to the flow of liquid passing through the expansion damping force adjustment passage, the second damper is,The suspension system includes a compression damping force adjustment passage that communicates with the second compression chamber and the second reservoir through the second piston rod, a compression damping force adjustment valve provided in the middle of the compression damping force adjustment passage, and a compression adjustment section provided on the second cap that can adjust the resistance that the compression damping force adjustment valve exerts on the flow of liquid passing through the compression damping force adjustment passage. With this suspension system configuration, the extension damping force and compression damping force can be adjusted at the upper ends of the first and second front forks.

[0011] Furthermore, in the suspension system, the compression damping force adjustment passage is formed by a lateral hole that opens from the side of the second piston rod and always faces the second reservoir, and a vertical hole provided on the second piston rod that connects the second compression chamber and the lateral hole, and the lateral hole may be positioned below the liquid level of the second reservoir. With a suspension system configured in this way, the compression damping force adjustment valve is always positioned in the liquid, so the compression damping force adjustment function is not impaired when the second damper contracts.

[0012] Furthermore, in the suspension system, the compression damping force adjustment passage is formed by a lateral hole that opens from the side of the second piston rod and always faces the second reservoir, and a vertical hole provided on the second piston rod that connects the second compression chamber and the lateral hole. The second damper has a check valve provided in series with the compression damping force adjustment valve in the middle of the compression damping force adjustment passage, which allows only the flow of liquid from the second compression chamber to the second reservoir, and the check valve may be positioned below the liquid level of the second reservoir. With a suspension system configured in this way, the compression damping force adjustment valve is always positioned in the liquid, so the compression damping force adjustment function is not impaired when the second damper contracts.

[0013] In the suspension system, both the first piston rod and the second piston rod are cylindrical, and the extension damping force adjustment valve has an extension needle that is axially movable inserted into the first piston rod and an extension annular valve seat provided on the inner circumference of the first piston rod, and the compression damping force adjustment valve has a compression needle that is axially movable inserted into the second piston rod and a compression annular valve seat provided on the inner circumference of the second piston rod, and the first damper has an extension control rod that is inserted into the first piston rod and transmits the power of the extension adjustment unit to the extension needle, and the second damper has a compression control rod that is inserted into the second piston rod and transmits the power of the compression adjustment unit to the compression needle, and the first damper and the second damper share common components except for the first piston rod, the second piston rod, the extension needle, the compression needle, the extension control rod and the compression control rod. With this suspension system configuration, the number of parts required for manufacturing the first and second dampers can be minimized, thereby reducing the manufacturing cost of the suspension system. [Effects of the Invention]

[0014] According to the suspension device of the present invention, the extension damping force and the compression damping force can be adjusted at the upper end of the front fork. [Brief explanation of the drawing]

[0015] [Figure 1] This is a front view of a saddle-type vehicle to which a suspension system according to one embodiment of the present invention is applied. [Figure 2] This is a cross-sectional view of the first front fork of a suspension system according to one embodiment of the present invention. [Figure 3] This is a cross-sectional view of the second front fork of a suspension system according to one embodiment of the present invention. [Figure 4] This is a cross-sectional view of the second front fork housing a modified version of the second damper. [Modes for carrying out the invention]

[0016] Hereinafter, the present invention will be described based on the embodiments shown in the drawings. As shown in FIG. 1, a suspension device S according to one embodiment includes a first front fork F1x and a second front fork F2y, and suspends a front wheel W from a vehicle body B of a straddle-type vehicle V such as a motorcycle or a trike.

[0017] Hereinafter, each part of the suspension device S will be described in detail. The first front fork F1x and the second front fork F2y include a plurality of members common to each other. In the description of each part of the first front fork F1x and the second front fork F2y, unless "first" and "second" are prefixed to the names of members in the present specification, the members of both the first front fork F1x and the second front fork F2y are referred to, unless otherwise specified. In addition, in the present specification, when a reference numeral attached to a member ends with x, it indicates that the member is a component of the first front fork F1x, and when a reference numeral attached to a member ends with y, it indicates that the member is a component of the second front fork F2y.

[0018] As shown in FIG. 1, the suspension device S includes a first front fork F1x, a second front fork F2y, and a pair of upper and lower brackets 1, 2 that clamp the upper ends of the first front fork F1x and the second front fork F2y. The brackets 1 and 2 are attached to a steering shaft rotatably inserted into a head pipe P provided at the tip of the vehicle body B of the straddle-type vehicle V, and are rotatably connected to the vehicle body B in the circumferential direction of the head pipe P. The upper ends of the first front fork F1x and the second front fork F2y are clamped by the brackets 1 and 2, which are rotatably connected to the vehicle body B in the circumferential direction of the head pipe P, and the axle Ws of the front wheel W is connected to the lower ends thereof. As described above, the suspension device S suspends the front wheel W from the vehicle body B of the straddle-type vehicle V by the pair of left and right front forks F1x, F2y.

[0019] The first front fork F1x, as shown in Figure 2, includes a first vehicle-body-side tube 3x, a first axle-side tube 4x axially movable relative to the first vehicle-body-side tube 3x, a first cap 5x closing the upper end of the first vehicle-body-side tube 3x, and a first axle-side tube 4 4x x, which closes the lower end of the first axle-side tube 4x and holds the axle Ws of the front wheel W. The first front fork comprises an expandable first fork body Fx having the first axle bracket 6x, and a first damper Dx accommodated in the first fork body Fx. Also, as shown in Figure 3, the second front fork F2y includes a second vehicle-body-side tube 3y, a second axle-side tube 4y axially movable relative to the second vehicle-body-side tube 3y, a second cap 5y closing the upper end of the second vehicle-body-side tube 3y, and a second axle bracket 6y which closes the lower end of the second axle-side tube 4y and holds the axle Ws of the front wheel W. The second front fork comprises an expandable second fork body Fy having the above components, and a second damper Dy accommodated in the second fork body Fy.

[0020] As shown in Figures 2 and 3, caps 5x, 5y are mounted on the open ends of the upper ends of the vehicle-body-side tubes 3x, 3y, and the upper ends of the vehicle-body-side tubes 3x, 3y are closed by the caps 5x, 5y. The caps 5x, 5y include annular outer ring portions 5ax, 5ay screwed onto the inner periphery of the upper ends of the vehicle-body-side tubes 3x, 3y, and inner cylindrical portions 5bx, 5by protruding downward in the drawings from the inner periphery of the outer ring portions 5ax, 5ay and screwed onto the upper ends of piston rods 11x, 11y described later. Furthermore, the inner cylindrical portions 5bx, 5by of the caps 5x, 5y are provided with a pair of elongated holes 5cx, 5cy that are radially opposite to each other and extend along the axial direction of the inner cylindrical portions 5bx, 5by.

[0021] The axle-side tubes 4x and 4y are inserted into the body-side tubes 3x and 3y from below, and can move relative to the body-side tubes 3x and 3y in the axial direction. The inner circumference of the lower end of the body-side tubes 3x and 3y is provided with annular bushings 7x and 7y and annular sealing members 8x and 8y that slide against the outer circumference of the axle-side tubes 4x and 4y, and the outer circumference of the upper end of the axle-side tubes 4x and 4y is fitted with annular bushings 9x and 9y that slide against the inner circumference of the body-side tubes 3x and 3y. Therefore, the body-side tubes 3x and 3y and the axle-side tubes 4x and 4y can move relative to each other in the axial direction without axial wobble due to the bushings 7x, 7y and 9x and 9y.

[0022] The lower ends of the axle-side tubes 4x, 4y are closed by axle brackets 6x, 6y which grip the axle Ws of the front wheel W, and the fork bodies Fx, Fy are connected to the front wheel W by the axle brackets 6x, 6y. The inside of the fork bodies Fx, Fy configured in this way is a space sealed from the outside by sealing members 8x, 8y. The axle brackets 6x, 6y are cylindrical and include bottomed cylindrical parts 6ax, 6ay which are screwed onto the outer circumference of the lower ends of the axle-side tubes 4x, 4y, and gripping parts 6bx, 6by which are connected to the bottom of the cylindrical parts 6ax, 6ay and grip the axle Ws. Although not shown in the figures, the axle brackets 6x, 6y are provided with mounting parts that allow for the attachment of brake calipers, fenders, etc.

[0023] The first damper Dx includes a first cylinder 10x connected to the first axle bracket 6x, a first piston rod 11x inserted into the first cylinder 10x so as to be axially movable and whose upper end is connected to the first cap 5x, and a first piston 12x connected to the first piston rod 11x and inserted into the first cylinder 10x, dividing the first cylinder 10x into a first extension chamber R1x and a first compression chamber R2x, which are filled with liquid, and generates a damping force that extends and retracts in accordance with the extension and retraction of the first fork body Fx, thereby hindering the extension and retraction of the first fork body Fx. When the first damper Dx is housed in the first fork body Fx in this manner, a reservoir Rx is formed outside the first damper Dx but inside the first fork body Fx where liquid is stored. Furthermore, the first damper Dx includes an extension damping force adjustment passage 20x connecting the first extension chamber R1x and the first compression chamber R2x, an extension damping force adjustment valve 21x provided in the middle of the extension damping force adjustment passage 20x, and an extension adjuster 22x provided on the first cap 5x as an extension adjustment part that can adjust the resistance that the extension damping force adjustment valve 21x exerts on the flow of liquid passing through the extension damping force adjustment passage 20x.

[0024] Furthermore, the second damper Dy includes a second cylinder 10y connected to the second axle bracket 6y, a second piston rod 11y inserted into the second cylinder 10y so as to be movable in the axial direction and whose upper end is connected to the second cap 5y, and a second piston 12y connected to the second piston rod 11y and inserted into the second cylinder 10y, dividing the second cylinder 10y into a second extension chamber R1y and a second compression chamber R2y, which are filled with liquid, and generates a damping force that extends and retracts in accordance with the extension and retraction of the second fork body Fy, thereby hindering the extension and retraction of the second fork body Fy. When the second damper Dy is housed in the second fork body Fy in this manner, a second reservoir Ry is formed outside the second damper Dy but inside the second fork body Fy, where liquid is stored. Furthermore, the second damper Dy includes a second compression chamber R2y and a compression damping force adjustment passage 23y that communicates with the outside of the second cylinder 10y through the second piston rod 11y and the second fork body Fy, a compression damping force adjustment valve 24y provided in the middle of the compression damping force adjustment passage 23y, and a compression adjuster 25y provided on the second cap 5y as a compression adjustment part that can adjust the resistance that the compression damping force adjustment valve 24y exerts on the flow of liquid passing through the compression damping force adjustment passage 23y.

[0025] The components constituting the first damper Dx and the second damper Dy are described below. The cylinders 10x and 10y are connected to the axle brackets 6x and 6y via base valve assemblies 13x and 13y, which are fixed to the axle brackets 6x and 6y in the fork bodies Fx and Fy. The cylinders 10x and 10y are provided with through holes 10ax and 10ay that open from the side of their lower ends and communicate the inside of the cylinders 10x and 10y with the reservoirs Rx and Ry. In addition, annular rod guides 15x and 15y are attached to the upper open ends of the cylinders 10x and 10y. The rod guides 15x and 15y are annular in shape and comprise guide portions 15ax and 15ay that slide against the outer circumference of piston rods 11x and 11y, which are screwed into the inner circumference of the upper ends of cylinders 10x and 10y and inserted through the inner circumference, and cylindrical case portions 15bx and 15by that protrude upward from the upper ends of the guide portions 15ax and 15ay. In this embodiment, the liquid filling the cylinders 10x and 10y and the reservoirs Rx and Ry is hydraulic fluid, but other liquids may be used.

[0026] The base valve assemblies 13x, 13y include annular partition walls 13ax, 13ay that fit above the through holes 10ax, 10ay of the cylinders 10x, 10y, and retaining members 13bx, 13by that are fixed to the axle brackets 6x, 6y by bolts 14x, 14y that pass through the bottom of the cylindrical portions 6ax, 6ay of the axle brackets 6x, 6y, and are screwed onto the lower ends of the cylinders 10x, 10y, while also holding the partition walls 13ax, 13ay. The retaining members 13bx and 13by include closing portions 13b1x and 13b1y that are screwed onto the inner circumference of the lower end of the cylinders 10x and 10y, below the through holes 10ax and 10ay, thereby closing the lower end of the cylinders 10x and 10y, and shaft portions 13b2x and 13b2y that protrude upward from the closing portions 13b1x and 13b1y, and to which the partition walls 13ax and 13ay are attached. In this way, the space inside the cylinders 10x and 10y between the partition walls 13ax and 13ay and the closing portions 13b1x and 13b1y is in communication with the reservoirs Rx and Ry via the through holes 10ax and 10ay, and the partition walls 13ax and 13ay divide the inside of the cylinders 10x and 10y into a pressure chamber R2x and R2y and a space in communication with the reservoirs Rx and Ry.

[0027] Furthermore, the partition walls 13ax and 13ay are provided with pressure-side damping passages 13a1x and 13a1y and suction passages 13a2x and 13a2y that connect the pressure-side chambers R2x and R2y to the aforementioned space. The pressure-side damping passages 13a1x and 13a1y are provided with pressure-side damping valves 32x and 32y that provide resistance to the flow of liquid from the pressure-side chambers R2x and R2y to the reservoirs Rx and Ry, while the suction passages 13a2x and 13a2y are provided with extension-side check valves 33x and 33y that allow only the flow of liquid from the reservoirs Rx and Ry to the pressure-side chambers R2x and R2y.

[0028] The piston rods 11x and 11y each comprise a cylindrical piston rod body 11ax and 11ay, and a cylindrical center rod 11bx and 11by connected to the lower ends of the piston rod bodies 11ax and 11ay to hold the pistons 12x and 12y. The upper ends of the piston rods 11x and 11y are screwed into the inner cylindrical portions 5bx and 5by of the caps 5x and 5y, and the lower ends are inserted into the cylinders 10x and 10y through the inner circumference of the rod guides 15x and 15y. The piston rods 11x and 11y can move relative to the cylinders 10x and 10y in the axial direction (up and down in the figure) together with the pistons 12x and 12y, while their radial movement is restricted by the rod guides 15x and 15y and the pistons 12x and 12y.

[0029] As shown in Figure 2, the center rod 11bx of the first piston rod 11x is cylindrical and includes a large-diameter portion 11b1x that screws onto the outer circumference of the lower end of the piston rod body 11ax, a small-diameter portion 11b2x which has a smaller outer diameter than the large-diameter portion 11b1x and on which the piston 12x is mounted, a port 11b3x provided on the large-diameter portion 11b1x and passing through the large-diameter portion 11b1x radially, and an extension-side annular valve seat 11b4x formed by a stepped portion on the inner circumference which is provided on the side of the small-diameter portion 11b2x that is on the side of the port 11b3x. An annular lock piece 31x is provided on the outer circumference of the piston rod body 11ax which enters into the case portion 15bx of the rod guide 15x when the first damper Dx is fully retracted. When the lock piece 31x enters the case portion 15bx, it increases the pressure inside the case portion 15bx and suppresses further contraction of the first damper Dx.

[0030] The center rod 11bx is cylindrical, and the opening at the tip of the center rod 11bx faces the first compression chamber R2x. Therefore, the inside of the center rod 11bx is connected to the port 11b3x, and the first extension chamber R1x and the first compression chamber R2x are in communication. In this way, an extension damping force adjustment passage 20x is formed inside the piston rod 11x.

[0031] The first piston 12x is annular in shape and includes an extension damping passage 12ax and a compression passage 12bx that connect the first extension chamber R1x and the first compression chamber R2x in parallel, and is fitted onto the outer circumference of the small diameter portion 11b2x of the center rod 11bx.

[0032] An annular extension damping valve 16x is provided on the first compression chamber R2x side of the first piston 12x, which opens and closes the extension damping passage 12ax and provides resistance to the flow of liquid passing through the extension damping passage 12ax from the first extension chamber R1x to the first compression chamber R2x. In this embodiment, the extension damping valve 16x is a leaf valve whose inner circumference is fixed to the center rod 11bx and whose outer circumference is allowed to deflect, but it may be a valve other than a leaf valve, and the number of stacked leaf valves can also be changed in the design.

[0033] An annular pressure-side check valve 17x is superimposed on the first extension chamber R1x side of the first piston 12x, which opens and closes the pressure-side passage 12bx and allows only the flow of liquid passing through the pressure-side passage 12bx from the first pressure-side chamber R2x to the first extension chamber R1x. In this embodiment, the pressure-side check valve 17x has an annular valve body that is movable axially relative to the piston 12x, and a mechanism that biases the valve body toward the piston 12x. do It is composed of a spring, but a valve of other structure may also be used.

[0034] Next, an extension damping force adjustment passage 20x provided within the piston rod 11x is provided with an extension damping force adjustment valve 21x, which includes an extension needle 21ax inserted into the piston rod 11x so as to be movable in the axial direction and capable of seating toward and away from the extension annular valve seat 11b4x, and a spring 21bx that biases the extension needle 21ax in a direction that separates it from the extension annular valve seat 11b4x. The extension needle 21ax includes a large-diameter guide portion 21a1x that slides against the inner circumference of the lower end of the piston rod body 11ax, a conical valve head 21a2x that extends downward from the guide portion 21a1x and seates toward and away from the extension annular valve seat 11b4x, and a seal ring 21a3x that is mounted on the outer circumference of the guide portion 21a1x and slides against the inner circumference of the piston rod body 11ax. Therefore, the extension needle 21ax is guided by the guide portion 21a1x within the piston rod 11x, allowing it to move axially without wobbling, while the seal ring 21a3x prevents the liquid from overcoming the guide portion 21a1x and moving upward within the piston rod 11x.

[0035] The extension damping force adjustment valve 21x can block the extension damping force adjustment passage 20x when the extension needle 21ax is seated on the extension annular valve seat 11b4x, and open the extension damping force adjustment passage 20x when the extension needle 21ax is retracted from the extension annular valve seat 11b4x. It can also adjust the resistance to the flow of liquid passing through the extension damping force adjustment passage 20x by adjusting the size of the gap (flow path area) between the extension needle 21ax and the extension annular valve seat 11b4x.

[0036] The flow path area in the extension damping force adjustment valve 21x is adjusted by operating the extension adjuster 22x housed in the inner circumference of the first cap 5x. The extension adjuster 22x has a threaded portion on its outer circumference and is rotatably inserted in the inner circumference of a cylindrical spring adjuster 26x, which is rotatably mounted in the inner cylinder portion 5bx of the first cap 5x. A feed screw mechanism is formed between the extension adjuster 22x and the spring adjuster 26x, and when the extension adjuster 22x is rotated relative to the spring adjuster 26x, the extension adjuster 22x moves vertically in Figure 2 within the first cap 5x. Between the extension adjuster 22x and the extension needle 21ax, a cylindrical extension control rod 27x is inserted into the piston rod body 11ax so as to be movable vertically in the axial direction in Figure 2, and the extension adjuster 22x moves vertically via the extension control rod 27x. of The displacement is transmitted to the extension needle 21ax. In this way, by operating the extension adjuster 22x provided on the first cap 5x at the upper end of the first front fork F1x, the flow area of ​​the extension damping force adjustment valve 21x can be changed to a larger or smaller size.

[0037] Furthermore, a threaded portion (not shown) is formed on the outer circumference of the lower end of the spring adjuster 26x, and a nut 28x is attached to the threaded portion on the outer circumference of the spring adjuster 26x. The nut 28x is equipped with a spring receiver 28ax that protrudes outward from the outer circumference of the inner cylinder portion 5bx through the elongated hole 5cx of the inner cylinder portion 5bx of the first cap 5x. A suspension spring 29x is interposed between the spring receiver 28ax and the upper end of the case portion 15bx of the rod guide 15x, and the suspension spring 29x biases the first fork body Fx to extend, thereby elastically supporting the vehicle body B of the saddle-type vehicle V. When the spring adjuster 26x is rotated, the rotation of the nut 28x is restricted by the inner cylinder portion 5bx, causing it to move vertically in Figure 2, and displacing the support position of the suspension spring 29x on the spring receiver 28ax in the vertical direction, thereby adjusting the vehicle height of the saddle-type vehicle V.

[0038] On the other hand, as shown in Figure 3, the piston rod body 11ay of the second piston rod 11y is provided with a lateral hole 11a1y. The piston rod body 11ax of the first piston rod 11x is not provided with a lateral hole, but the piston rod body 11ay of the second piston rod 11y is provided with a lateral hole 11a1y, and in this respect, the piston rod body 11ax and the piston rod body 11ay have different structures. The lateral hole 11a1y is located above the case portion 15by and communicates with the second reservoir Ry even when the second damper Dy is fully contracted and the piston rod 11y is inserted to its maximum extent into the cylinder 10y. Thus, the lateral hole 11a1y is always in communication with the second reservoir Ry. Furthermore, the lateral hole 11a1y is positioned so that even when the second damper Dy is fully extended and the piston rod 11y moves as far upward as possible from the cylinder 10y in Figure 3, it is always below the liquid level Oy of the liquid stored in the second reservoir Ry.

[0039] Furthermore, an annular lock piece 31y is provided on the outer circumference of the piston rod body 11ay, below the lateral hole 11a1y, which enters into the case portion 15by of the rod guide 15y when the second damper Dy is fully retracted. When the lock piece 31y enters the case portion 15by, it increases the pressure inside the case portion 15by, suppressing further contraction of the second damper Dy.

[0040] Furthermore, the center rod 11by of the second piston rod 11y is cylindrical and includes a large-diameter portion 11b1y that screws onto the outer circumference of the lower end of the piston rod body 11ay, a small-diameter portion 11b2y which has a smaller outer diameter than the large-diameter portion 11b1y and on which the piston 12y is mounted, and a compression-side annular valve seat 11b3y formed by a stepped portion provided on the inner circumference. The center rod 11bx of the first piston rod 11x is equipped with a port 11b3x, but the center rod 11by of the second piston rod 11y is not equipped with a port, and in this respect, the structure of the center rod 11bx and the center rod 11by differs.

[0041] Furthermore, the piston rod body 11ay and the center rod 11by are cylindrical, and the opening at the tip of the center rod 11by faces the second pressure side chamber R2y, so the second pressure side chamber R2y is in communication with the reservoir Ry through the inside of the second piston rod 11y and the lateral hole 11a1y. In this way, the second piston rod 11y but By being cylindrical, a vertical hole is formed that connects the horizontal hole 11a1y to the second compression side chamber R2y, and a compression side damping force adjustment passage 23y is formed inside the second piston rod 11y.

[0042] The second piston 12y is annular in shape and includes an extension damping passage 12ay and a compression passage 12by that connect the second extension chamber R1y and the second compression chamber R2y in parallel, and is fitted onto the outer circumference of the small diameter portion 11b2y of the center rod 11by.

[0043] An annular extension damping valve 16y is provided on the second compression chamber R2y side of the second piston 12y, which opens and closes the extension damping passage 12ay and provides resistance to the flow of liquid passing through the extension damping passage 12ay from the second extension chamber R1y to the second compression chamber R2y. In this embodiment, the extension damping valve 16y is a leaf valve whose inner circumference is fixed to the center rod 11by and whose outer circumference is allowed to flex, but it may be a valve other than a leaf valve, and the number of stacked leaf valves can also be changed in the design.

[0044] An annular pressure-side check valve 17y is superimposed on the second extension chamber R1y side of the second piston 12y, which opens and closes the pressure-side passage 12by and allows only the flow of liquid passing through the pressure-side passage 12by from the second pressure-side chamber R2y to the second extension chamber R1y. In this embodiment, the pressure-side check valve 17y has an annular valve body that is movable axially relative to the piston 12y, and a mechanism that biases the valve body toward the piston 12y. do It is composed of a spring, but a valve of other structure may also be used.

[0045] Next, a compression damping force adjustment valve 24y is provided in a compression damping force adjustment passage 23y located within the piston rod 11y. This valve includes a compression needle 24ay that is inserted into the piston rod 11y so as to be movable in the axial direction and is capable of seating toward and away from the compression annular valve seat 11b3y, and a spring 24by that biases the compression needle 24ay in a direction that separates it from the compression annular valve seat 11b3y. The compression needle 24ay includes a large-diameter guide portion 24a1y that slides against the inner circumference of the lower end of the piston rod body 11ay, and a conical valve head 24a2y that extends downward from the guide portion 24a1y and seates toward and away from the compression annular valve seat 11b3y. Therefore, the compression needle 24ay can move axially without axial wobble, guided by the guide portion 24a1y within the piston rod 11y.

[0046] The compression damping force adjustment valve 24y can block the compression damping force adjustment passage 23y when the compression needle 24ay is seated on the compression annular valve seat 11b3y, and open the compression damping force adjustment passage 23y when the compression needle 24ay is retracted from the compression annular valve seat 11b3y. The resistance to the flow of liquid passing through the compression damping force adjustment passage 23y can be adjusted by adjusting the size of the gap (flow path area) between the compression needle 24ay and the compression annular valve seat 11b3y. The outer circumference of the guide portion 24a1y is provided with a notch 24a3y, and since the guide portion 24a1y does not block the compression damping force adjustment passage 23y, communication between the second compression chamber R2y and the second reservoir Ry via the compression damping force adjustment passage 23y is ensured when the compression damping force adjustment valve 24y is open.

[0047] The flow path area in the compression damping force adjustment valve 24y is adjusted by operating the compression adjuster 25y, which is housed on the inner circumference of the second cap 5y. The compression adjuster 25y has a threaded portion on its outer circumference and is rotatably inserted in the circumferential direction into the inner circumference of a cylindrical spring adjuster 26y, which is rotatably mounted in the circumferential direction within the inner cylinder portion 5by of the second cap 5y. A feed screw mechanism is formed between the compression adjuster 25y and the spring adjuster 26y, and when the compression adjuster 25y is rotated relative to the spring adjuster 26y, the compression adjuster 25y moves vertically within the second cap 5y as shown in Figure 3. Between the compression adjuster 25y and the compression needle 24ay, a cylindrical compression control rod 30y is inserted into the piston rod body 11ay so as to be movable in the vertical direction in the axial direction as shown in Figure 3. The vertical displacement of the compression adjuster 25y is transmitted to the compression needle 24ay via the compression control rod 30y. In this way, by operating the compression adjuster 25y provided on the second cap 5y at the upper end of the second front fork F2y, the flow area of ​​the compression damping force adjustment valve 24y can be changed in size.

[0048] Furthermore, a threaded portion (not shown) is formed on the outer circumference of the lower end of the spring adjuster 26y, and a nut 28y is attached to the threaded portion on the outer circumference of the spring adjuster 26y. The nut 28y is equipped with a spring receiver 28ay that protrudes outward from the inner cylinder portion 5by through the elongated hole 5cy of the inner cylinder portion 5by of the second cap 5y. A suspension spring 29y is interposed between the spring receiver 28ay and the upper end of the case portion 15by of the rod guide 15y, and the suspension spring 29y biases the second fork body Fy to extend, thereby elastically supporting the vehicle body B of the saddle-type vehicle V. When the spring adjuster 26y is rotated, the rotation of the nut 28y is restricted by the inner cylinder portion 5by, causing it to move vertically in Figure 3, and displacing the support position of the suspension spring 29y on the spring receiver 28ay in the vertical direction, thereby adjusting the vehicle height of the saddle-type vehicle V.

[0049] The suspension system S is configured as described above, and the operation of the suspension system S will be explained below. First, when the first front fork F1x and the second front fork F2y in the suspension system S extend, the first damper Dx and the second damper Dy also extend together. When the first damper Dx and the second damper Dy extend, the pistons 12x and 12y move upward in the figure within the cylinders 10x and 10y, reducing the extension chambers R1x and R1y and expanding the compression chambers R2x and R2y. As a result, the fluid pushes open the extension damping valves 16x and 16y of the pistons 12x and 12y, passes through the extension damping passages 12ax and 12ay, and moves from the extension chambers R1x and R1y to the compression chambers R2x and R2y. The extension damping valves 16x and 16y provide resistance to the flow of liquid through the extension damping passages 12ax and 12ay, causing the pressure in the extension chambers R1x and R1y to increase.

[0050] In the first damper Dx, the extension damping force adjustment passage 20x is parallel to the extension damping passage 12ax and connects the first extension chamber R1x and the first compression chamber R2x. The extension damping force adjustment passage 20x is provided with an extension damping force adjustment valve 21x. Therefore, when the extension damping force adjustment valve 21x is open, the liquid in the first extension chamber R1x moves to the first compression chamber R2x not only through the extension damping passage 12ax but also through the extension damping force adjustment passage 20x. Therefore, when operating the extension adjuster 22x... evening By adjusting the flow area between the extension needle 21ax and the extension annular valve seat 11b4x in the extension damping force adjustment valve 21x, the resistance to the flow of liquid passing through the extension damping force adjustment passage 20x can be adjusted, thereby allowing the pressure in the first extension chamber R1x to be adjusted to a high or low level when the first damper Dx is extended.

[0051] On the other hand, as the piston rods 11x and 11y retract from the cylinders 10x and 10y, the expanding pressure chambers R2x and R2y will have a liquid shortage equal to the volume of the piston rods 11x and 11y retracting from the cylinders 10x and 10y. This liquid shortage is supplied from the reservoirs Rx and Ry to the pressure chambers R2x and R2y via the suction passages 13a2x and 13a2y when the extension check valves 33x and 33y open. Therefore, the pressure in the pressure chambers R2x and R2y becomes approximately equal to the pressure in the reservoirs Rx and Ry.

[0052] Thus, when the suspension device S extends, the pressure in the extension chambers R1x and R1y increases to become higher than the pressure in the compression chambers R2x and R2y, acting on the pistons 12x and 12y. The first damper Dx generates an extension damping force that hinders the extension of the first front fork F1x, and the second damper Dy generates an extension damping force that hinders the extension of the second front fork F2y.

[0053] Furthermore, in the first damper Dx, the rebound damping force can be adjusted by adjusting the resistance that the rebound damping force adjustment valve 21x imparts to the flow of liquid from the first rebound chamber R1x to the first compression chamber R2x in the rebound damping force adjustment passage 20x. When the entire suspension system S extends, the damping force that hinders the extension is the sum of the damping forces generated by the first damper Dx and the second damper Dy. Therefore, by adjusting the rebound damping force of the first damper Dx in the first front fork F1x, the rebound damping force when the suspension system S extends can be adjusted.

[0054] Next, when the first front fork F1x and the second front fork F2y in the suspension system S contract, the first damper Dx and the second damper Dy also contract. When the first damper Dx and the second damper Dy contract, the pistons 12x and 12y move downward in the figure within the cylinders 10x and 10y, reducing the compression chambers R2x and R2y and expanding the extension chambers R1x and R1y. As a result, the liquid pushes open the compression check valves 17x and 17y of the pistons 12x and 12y, passes through the compression passages 12bx and 12by, and moves from the compression chambers R2x and R2y to the extension chambers R1x and R1y. Furthermore, as the piston rods 11x and 11y enter the cylinders 10x and 10y, the volume of liquid in cylinders 10x and 10y increases by the volume of liquid that the piston rods 11x and 11y enter. This excess liquid pushes open the compression damping valves 32x and 32y, allowing it to move from the compression chambers R2x and R2y to the reservoirs Rx and Ry through the compression damping passages 13a1x and 13a1y. The compression check valves 17x and 17y provide almost no resistance to the liquid flow, making the pressure in the extension chambers R1x and R1y and the pressure in the compression chambers R2x and R2y approximately equal. On the other hand, the compression damping valves 32x and 32y provide resistance to the liquid flow passing through the compression damping passages 13a1x and 13a1y, causing the pressure in cylinders 10x and 10y to rise.

[0055] In the second damper Dy, the compression damping force adjustment passage 23y is parallel to the compression damping passage 13a1y and connects the second compression chamber R2y and the second reservoir Ry. A compression damping force adjustment valve 24y is provided in the compression damping force adjustment passage 23y. Therefore, when the compression damping force adjustment valve 24y is open, the liquid in the second compression chamber R2y moves to the second reservoir Ry not only through the compression damping passage 13a1y but also through the compression damping force adjustment passage 23y. Therefore, when operating the compression adjuster 25y... evening By adjusting the flow area between the compression needle 24ay and the compression annular valve seat 11b3y in the compression damping force adjustment valve 24y, the resistance to the flow of liquid passing through the compression damping force adjustment passage 23y can be adjusted, thereby allowing the pressure inside the cylinder 10y to be adjusted to a high or low level when the second damper Dy is contracted.

[0056] Thus, when the suspension device S contracts, the pressure in the extension chambers R1x, R1y and the pressure in the compression chambers R2x, R2y rise approximately equally. The pressure in the extension chambers R1x, R1y acts on the upper surface of the pistons 12x, 12y, and the pressure in the compression chambers R2x, R2y acts on the lower surface of the pistons 12x, 12y. However, since the pistons 12x, 12y are connected to the piston rods 11x, 11y, the pressure-receiving area on the lower surface of the pistons 12x, 12y is larger than the pressure-receiving area on the upper surface. Therefore, the first damper Dx generates a compression damping force that hinders the contraction of the first front fork F1x, and the second damper Dy generates a compression damping force that hinders the contraction of the second front fork F2y.

[0057] Furthermore, in the second damper Dy, the compression damping force adjustment valve 24y adjusts the resistance that the compression damping force adjustment passage 23y imposes on the flow of liquid from the second compression chamber R2y to the second reservoir Ry. Compression side The damping force can be adjusted. contraction The damping force that prevents this is the sum of the damping forces generated by the first damper Dx and the second damper Dy. Therefore, by adjusting the compression damping force of the second damper Dy in the second front fork F2y, the damping force during the contraction of the suspension system S is controlled. Compression side The damping force can be adjusted.

[0058] Therefore, in the suspension system S of this embodiment, the rebound damping force can be adjusted by operating the rebound adjuster 22x attached to the first cap 5x at the upper end of the first front fork F1x, and the compression damping force can be adjusted by operating the compression adjuster 25y attached to the second cap 5y at the upper end of the second front fork F2y.

[0059] As described above, the suspension device S of this embodiment comprises a first front fork F1x and a second front fork F2y that suspend the front wheels W of a saddle-type vehicle V from the vehicle body B, the first front fork F1x comprises a first vehicle body side tube 3x, a first axle side tube 4x that is movable in the axial direction relative to the first vehicle body side tube 3x, a first cap 5x that closes the upper end of the first vehicle body side tube 3x, and the first axle side tube4xThe first fork body Fx is extendable and retractable, having a first axle bracket 6x that closes the lower end of the first fork and holds the axle Ws of the front wheel W; a first cylinder 10x connected to the first axle bracket 6x; a first piston rod 11x that is inserted into the first cylinder 10x so as to be movable in the axial direction and whose upper end is connected to a first cap 5x; and a first piston 12x that is connected to the first piston rod 11x and inserted into the first cylinder 10x, dividing the first cylinder 10x into a first extension chamber R1x and a first compression chamber R2x, which are filled with liquid. The first front fork comprises a first damper Dx that expands and contracts in accordance with the expansion and contraction of the first fork body Fx and generates a damping force that hinders the expansion and contraction of the first fork body Fx, and a first reservoir Rx that stores liquid in the space between the first fork body Fx and the first damper Dx, and the second front fork F2y comprises a second vehicle-side tube 3y, a second axle-side tube 4y that is movable in the axial direction relative to the second vehicle-side tube 3y, a second cap 5y that closes the upper end of the second vehicle-side tube 3y, and a second axle that closes the lower end of the second axle-side tube 4y and holds the axle Ws of the front wheel W The second fork body Fy is extendable and retractable with respect to a bracket 6y, a second cylinder 10y is connected to the second axle bracket 6y, a second piston rod 11y is inserted into the second cylinder 10y so as to be movable in the axial direction and whose upper end is connected to the second cap 5y, and a second piston 12y is connected to the second piston rod 11y and inserted into the second cylinder 10y, dividing the inside of the second cylinder 10y into a second extension chamber R1y and a second compression chamber R2y, and extends and retracts in accordance with the extension and retraction of the second fork body Fy, thereby hindering the extension and retraction of the second fork body Fy. The first damper Dx has a second damper Dy that generates a damping force, and a second reservoir Ry is formed in the space between the second fork body Fy and the second damper Dy to store liquid. The first damper Dx has an extension damping force adjustment passage 20x that connects the first extension chamber R1x and the first compression chamber R2x, an extension damping force adjustment valve 21x provided in the middle of the extension damping force adjustment passage 20x, and an extension adjuster (extension adjustment part) 22x provided on the first cap 5x that can adjust the resistance that the extension damping force adjustment valve 21x gives to the flow of liquid passing through the extension damping force adjustment passage 20x. The second damper Dy isIt has a compression damping force adjustment passage 23y that communicates with the second compression chamber R2y and the second reservoir Ry through the second piston rod 11y, a compression damping force adjustment valve 24y provided in the middle of the compression damping force adjustment passage 23y, and a compression adjuster (compression adjustment part) 25y provided on the second cap 5y that can adjust the resistance that the compression damping force adjustment valve 24y exerts on the flow of liquid passing through the compression damping force adjustment passage 23y.

[0060] In the suspension system S configured in this way, the first damper Dx in the first front fork F1x is capable of generating damping force when it extends and contracts, and the extension damping force of the first damper Dx can be adjusted by an extension adjuster (extension adjustment unit) that operates the extension damping force adjustment valve 21x, and the second damper Dy in the second front fork F2y is capable of generating damping force when it extends and contracts, and the second damper Dy can be adjusted by a compression adjuster (compression adjustment unit) 25y that operates the compression damping force adjustment valve 24y. pressure The rebound damping force can be adjusted. In this configuration of the suspension system S, a rebound adjuster (rebound adjustment unit) 22x that operates the rebound damping force adjustment valve 21x is attached to the first cap 5x at the upper end of the first front fork F1x, and a compression adjuster (compression adjustment unit) 25y that operates the compression damping force adjustment valve 24y is attached to the second cap 5y at the upper end of the second front fork F2y. Therefore, according to the suspension system S of this embodiment, the rebound damping force and compression damping force can be adjusted at the upper ends of the first front fork F1x and the second front fork F2y.

[0061] Furthermore, in the suspension system S of this embodiment, the extension adjustment section is a manually operable extension adjuster 22x, and the compression adjustment section is a manually operable compression adjuster 25y. The user of the suspension system S can adjust the extension damping force by operating the extension adjuster 22x at the upper end of the first front fork F1x while remaining seated in the saddle-type vehicle V, and can also adjust the compression damping force by operating the compression adjuster 25y at the upper end of the second front fork F2y. In addition, with the suspension system S of this embodiment, the user is not forced to dismount and bend down to adjust the extension damping force and compression damping force, making it easy to adjust the extension damping force and compression damping force.

[0062] Furthermore, in the suspension system S of this embodiment, both the first damper Dx and the second damper Dy generate damping force when extending and contracting. Therefore, compared to the case where the first damper Dx generates damping force only when extending and the second damper Dy generates damping force only when contracting, the maximum pressure in the cylinders 10x and 10y can be reduced. Thus, the suspension system S of this embodiment makes it possible to reduce the weight of the components constituting the first damper Dx and the second damper Dy, and also reduces costs.

[0063] As mentioned above, the suspension system S is equipped with an extension adjuster 22x as an extension adjustment section for adjusting the flow area of ​​the extension damping force adjustment valve 21x, and a compression adjuster 25y as a compression adjustment section for adjusting the flow area of ​​the compression damping force adjustment valve 24y. However, the extension adjustment section and the compression adjustment section may be a linear actuator equipped with a solenoid, or a linear actuator composed of a rotary motor and a feed screw mechanism that converts the rotation of the motor's rotor into linear motion. In a suspension system S configured in this way, it is not necessary to place the linear actuator close to the ground, the linear actuator can be mounted on the upper ends of the first front fork F1x and the second front fork F2y, and the protection of the linear actuator and the routing of wiring to the linear actuator are also made easier.

[0064] Furthermore, in the suspension device S of this embodiment, as described above, the extension damping force adjustment valve 21x is a needle valve, but it may also be a valve equipped with a shutter that opens and closes a port 11b3x provided on the piston rod 11x by axial or circumferential displacement. Furthermore, in the suspension device S of this embodiment, as described above, the compression damping force adjustment valve 24y is a needle valve, but it may also be a valve equipped with a shutter that opens and closes a lateral hole 11a1y provided on the piston rod 11y by axial or circumferential displacement. The extension damping force adjustment valve 21x and the compression damping force adjustment valve 24y may consist of a valve body that can seat on and off the annular valve seats 11b4x and 11b3y, and a spring that biases the valve body to seat on the annular valve seats 11b4x and 11b3y. In this case, the spring biasing force can be adjusted with the extension adjuster 22x to change the opening pressure of the extension damping force adjustment valve 21x, thereby adjusting the resistance to the flow of liquid passing through the extension damping force adjustment passage 20x. The spring biasing force can be adjusted with the compression adjuster 25y to change the opening pressure of the compression damping force adjustment valve 24y, thereby adjusting the resistance to the flow of liquid passing through the compression damping force adjustment passage 23y. Thus, even if the extension damping force adjustment valve 21x and the compression damping force adjustment valve 24y are changed to valves other than needle valves, the extension adjustment section and the compression adjustment section may be replaced with linear actuators instead of adjusters 22x and 25y.

[0065] Furthermore, in the suspension device S of this embodiment, the compression damping force adjustment passage 23y is formed by a lateral hole 11a1y that opens from the side of the second piston rod 11y and always faces the second reservoir Ry, and a vertical hole provided in the second piston rod 11y that connects the second compression chamber R2y and the lateral hole 11a1y, with the lateral hole 11a1y positioned below the liquid level Oy of the second reservoir Ry. With the suspension device S configured in this way, even if the second front fork F2y does not extend or retract for a long time, the lateral hole 11a1y is always positioned below the liquid level Oy regardless of the extension or retraction state of the second damper Dy, so the liquid level in the compression damping force adjustment passage 23y does not fall below the compression damping force adjustment valve 24y. If the liquid level in the compression damping adjustment passage 23y were to drop below the compression damping adjustment valve 24y, the compression damping force would not be adjustable until the liquid level in the compression damping adjustment passage 23y rose to reach the compression damping adjustment valve 24y after the second front fork F2y had extended and retracted several times. In contrast, with the suspension device S configured as described above, the compression damping adjustment valve 24y is always submerged in liquid, the liquid level in the compression damping adjustment passage 23y does not drop below the compression damping adjustment valve 24y, and the compression damping force adjustment function of the compression damping adjustment valve 24y is not impaired when the second damper Dy contracts. Furthermore, even if the lateral hole 11a1y is not always positioned below the liquid level Oy, the effect of the present invention, which allows for easy adjustment of the extension damping force and the compression damping force, is not lost.

[0066] Furthermore, in the suspension device S of this embodiment, the first piston rod 11x and the second piston rod 11y are both cylindrical, the extension damping force adjustment valve 21x has an extension needle 21ax inserted into the first piston rod 11x so as to be movable in the axial direction and an extension annular valve seat 11b4x provided on the inner circumference of the first piston rod 11x, the compression damping force adjustment valve 24y has a compression needle 24ay inserted into the second piston rod 11y so as to be movable in the axial direction and a compression annular valve seat 11b3y provided on the inner circumference of the second piston rod 11y, and the first damper Dx is inserted into the first piston rod 11x and has an extension adjuster (extension adjustment part) 22x so as to be movable in the axial direction extend Side needle 21ax The first damper Dx and the second damper Dy have an extension control rod 27x that transmits to the first piston rod 11y, and a compression control rod 30y that is inserted into the second piston rod 11y and transmits the axial movement of the compression adjuster (compression adjustment part) 25y to the compression needle 24ay. 21ax Except for the compression needle 24ay, the extension control rod 27x, and the compression control rod 30y, the components are common. With the suspension device S configured in this way, the first damper Dx and the second damper Dy are connected to the first piston rod 11x, the second piston rod 11y, and the extension needle 21ax Except for the compression needle 24ay, the extension control rod 27x, and the compression control rod 30y, the first damper Dx and the second damper Dy are made of the same parts, so the number of parts can be kept to a minimum when manufacturing them, thereby reducing the manufacturing cost of the suspension device S. Furthermore, in the suspension device S of this embodiment, the first fork body Fx and the second fork body Fy are also made of the same parts, so the manufacturing cost of the suspension device S can be reduced even further.

[0067] In the suspension system S of the aforementioned embodiment, the second front fork F2y is positioned such that the lateral hole 11a1y is always located below the liquid level Oy in the second reservoir Ry relative to the second piston rod 11y, so as to prevent any delay in the generation of damping force when the second damper Dy switches from extension to compression, however, as in the modified example shown in Figure 4, a check valve 34y may be installed in series with the compression damping force adjustment valve 24y in the middle of the compression damping force adjustment passage 23y, always located below the liquid level Oy in the second reservoir Ry, allowing only the flow of liquid from the second compression chamber R2y to the second reservoir Ry.

[0068] The check valve 34y comprises a flanged cylindrical valve seat 34ay, a spherical valve body 34by that can seat on and off the valve seat 34ay, a bottomed cylindrical case 34cy with holes on its sides and bottom that is mounted on the outer circumference of the cylindrical portion of the valve seat 34ay, and a spring 34dy interposed between the case 34cy and the valve body 34by to bias the valve body 34by to seat on the valve seat 34ay. Thus, the check valve 34y is cartridge-type and is housed within the large-diameter portion 11b1y of the center rod 11by that holds the piston 12y. The check valve 34y is fixed within the piston rod 11y by the flange of the valve seat 34ay being sandwiched between the tip of the piston rod body 11ay and the stepped portion between the large-diameter portion 11b1y and the small-diameter portion 11b2y of the center rod 11by. By cartridge-type the check valve 34y in this way, installation within the piston rod 11y is easy. Furthermore, in this second damper D1y, the check valve 34y is housed inside the center rod 11by. As shown in Figure 4, a compression damping force adjustment valve 24y is provided inside the inner cylinder portion 5by of the second cap 5y, and a passage 40y is provided in the second cap 5y that connects the second reservoir Ry and the inside of the piston rod 11y.

[0069] In the second damper Dy1 configured in this way, the check valve 34y is positioned below the liquid level Oy, so the liquid in the compression damping force adjustment passage 23y does not descend due to the check valve 34y, and the compression damping force adjustment valve 24y is always submerged in the liquid. Therefore, in the suspension device S in which the second damper Dy1 of the first modified example is housed in the second front fork F2y, the compression damping force adjustment function of the compression damping force adjustment valve 24y is not impaired when the second damper Dy1 is compressed.

[0070] Regarding the arrangement of the compression damping force adjustment valve 24y and the check valve 34y with respect to the compression damping force adjustment passage 23y, in order to prevent a delay in damping force generation in the second damper Dy1, the compression damping force adjustment valve 24y and the check valve 34y should be arranged in series, and the check valve 34y should always be positioned below the liquid level Oy of the second reservoir Ry. As long as these conditions are met, the arrangement of the compression damping force adjustment valve 24y and the check valve 34y can be arbitrarily determined. Therefore, as shown in Figure 4, the compression damping force adjustment valve 24y may be provided inside the inner cylinder portion 5by of the second cap 5y, and a structure may be adopted in the second cap 5y that connects the second reservoir Ry and the inside of the piston rod 11y, or as shown in Figure 3, the compression damping force adjustment valve 24y may be provided inside the piston rod 11y. Furthermore, by housing the check valve 34y within the large-diameter section 11b1y, which provides space within the center rod 11by, the check valve 34y can be easily installed on the piston rod 11y. Also, since the check valve 34y does not extend outside the cylinder 10y even when the second damper D1y is at full stroke, the check valve 34y can be reliably positioned below the liquid level Oy. In addition, as mentioned above, cartridgeizing the check valve 34y makes it easier to install on the second damper D1y, but the structure can be freely redesigned as long as it functions as a check valve.

[0071] Although preferred embodiments of the present invention have been described in detail above, modifications, alterations, and changes are permitted as long as they do not deviate from the scope of the claims. [Explanation of Symbols]

[0072] 3x...First body-side tube, 3y...Second body-side tube, 4x...First axle-side tube, 4y...Second axle-side tube, 5x...First cap, 5y...Second cap, 6x...First axle bracket, 6y...Second axle bracket, 10x...First cylinder, 10y...Second cylinder, 11x...First piston rod, 11b4x...Rebound annular valve seat, 11y...Second piston rod, 11a1y...Transverse hole, 11b3y...Compression annular valve seat, 12x...First piston, 12y...Second piston, 20x...Rebound damping force Adjustment passage, 21x... Rebound damping force adjustment valve, 21ax... Rebound needle, 22x... Rebound adjuster (rebound adjustment part), 23y... Compression damping force adjustment passage, 24y... Compression damping force adjustment valve, 24ay... Compression needle, 25y... Compression adjuster (compression adjustment part), 27x... Rebound control rod, 30y... Compression control rod, 34y... Check valve, B... Body, Dx... 1st damper Pa, Dy, D1y... Second damper, F1x... First front fork, F2y... Second front fork, Fx... First fork body, Fy... Second fork body, O... Liquid level, S... Suspension system, Rx... First reservoir, Ry... Second reservoir, R1x... First extension chamber, R1y... Second extension chamber, R2x... First compression chamber, R2y... Second compression chamber, V... Saddle-type vehicle, W... Front wheel, Ws... Axle

Claims

1. A suspension system having a first front fork and a second front fork that suspend the front wheels of a saddle-type vehicle to the vehicle body, The first front fork is, A first fork body that is extendable and retractable, having a first body-side tube, a first axle-side tube that is movable axially relative to the first body-side tube, a first cap that closes the upper end of the first body-side tube, and a first axle bracket that closes the lower end of the first axle-side tube and holds the axle of the front wheel, The first fork includes a first cylinder connected to the first axle bracket, a first piston rod inserted into the first cylinder so as to be movable in the axial direction and whose upper end is connected to the first cap, and a first piston connected to the first piston rod and inserted into the first cylinder to divide the inside of the first cylinder into a first extension chamber and a first compression chamber, and a first damper which expands and contracts in accordance with the expansion and contraction of the first fork body and generates a damping force that hinders the expansion and contraction of the first fork body, A first reservoir is formed in the space between the first fork body and the first damper to store liquid. The second front fork is A second fork body that is extendable and retractable, having a second body-side tube, a second axle-side tube that is movable axially relative to the second body-side tube, a second cap that closes the upper end of the second body-side tube, and a second axle bracket that closes the lower end of the second axle-side tube and holds the front wheel axle, The second fork has a second cylinder connected to the second axle bracket, a second piston rod inserted into the second cylinder so as to be movable in the axial direction and whose upper end is connected to the second cap, and a second piston connected to the second piston rod and inserted into the second cylinder to divide the inside of the second cylinder into a second extension chamber and a second compression chamber, and a second damper which expands and contracts in accordance with the expansion and contraction of the second fork body and generates a damping force that hinders the expansion and contraction of the second fork body, A second reservoir is formed in the space between the second fork body and the second damper to store liquid. The first damper includes an extension damping force adjustment passage connecting the first extension chamber and the first compression chamber, an extension damping force adjustment valve provided in the middle of the extension damping force adjustment passage, and an extension adjustment section provided on the first cap that can adjust the resistance that the extension damping force adjustment valve imparts to the flow of liquid passing through the extension damping force adjustment passage. The second damper has a compression damping force adjustment passage that communicates with the second compression chamber and the second reservoir through the second piston rod, a compression damping force adjustment valve provided in the middle of the compression damping force adjustment passage, and a compression adjustment section provided in the second cap that can adjust the resistance that the compression damping force adjustment valve imparts to the flow of liquid passing through the compression damping force adjustment passage. The compression damping force adjustment passage is formed by a transverse hole that opens from the side of the second piston rod and always faces the second reservoir, and a vertical hole provided on the second piston rod that connects the second compression chamber and the transverse hole. The aforementioned lateral hole is positioned below the liquid level of the liquid in the second reservoir. A suspension system characterized by the following features.

2. A suspension system having a first front fork and a second front fork for suspending the front wheels of a saddle-type vehicle to the vehicle body, The first front fork is, A first fork body that is extendable and retractable, having a first body-side tube, a first axle-side tube that is movable axially relative to the first body-side tube, a first cap that closes the upper end of the first body-side tube, and a first axle bracket that closes the lower end of the first axle-side tube and holds the axle of the front wheel, The first fork includes a first cylinder connected to the first axle bracket, a first piston rod inserted into the first cylinder so as to be movable in the axial direction and whose upper end is connected to the first cap, and a first piston connected to the first piston rod and inserted into the first cylinder to divide the inside of the first cylinder into a first extension chamber and a first compression chamber, and a first damper which expands and contracts in accordance with the expansion and contraction of the first fork body and generates a damping force that hinders the expansion and contraction of the first fork body, A first reservoir is formed in the space between the first fork body and the first damper to store liquid. The second front fork is A second fork body that is extendable and retractable, having a second body-side tube, a second axle-side tube that is movable axially relative to the second body-side tube, a second cap that closes the upper end of the second body-side tube, and a second axle bracket that closes the lower end of the second axle-side tube and holds the front wheel axle, The second fork has a second cylinder connected to the second axle bracket, a second piston rod inserted into the second cylinder so as to be movable in the axial direction and whose upper end is connected to the second cap, and a second piston connected to the second piston rod and inserted into the second cylinder to divide the inside of the second cylinder into a second extension chamber and a second compression chamber, and a second damper which expands and contracts in accordance with the expansion and contraction of the second fork body and generates a damping force that hinders the expansion and contraction of the second fork body, A second reservoir is formed in the space between the second fork body and the second damper to store liquid. The first damper includes an extension damping force adjustment passage connecting the first extension chamber and the first compression chamber, an extension damping force adjustment valve provided in the middle of the extension damping force adjustment passage, and an extension adjustment section provided on the first cap that can adjust the resistance that the extension damping force adjustment valve imparts to the flow of liquid passing through the extension damping force adjustment passage. The second damper has a compression damping force adjustment passage that communicates with the second compression chamber and the second reservoir through the second piston rod, a compression damping force adjustment valve provided in the middle of the compression damping force adjustment passage, and a compression adjustment section provided in the second cap that can adjust the resistance that the compression damping force adjustment valve imparts to the flow of liquid passing through the compression damping force adjustment passage. The compression damping force adjustment passage is formed by a transverse hole that opens from the side of the second piston rod and always faces the second reservoir, and a vertical hole provided on the second piston rod that connects the second compression chamber and the transverse hole. The second damper has a check valve provided in series with the compression damping force adjustment valve in the middle of the compression damping force adjustment passage, which allows only the flow of liquid from the second compression chamber to the second reservoir. The check valve is positioned below the liquid level of the liquid in the second reservoir. A suspension system characterized by the following features.

3. A suspension system having a first front fork and a second front fork for suspending the front wheels of a saddle-type vehicle to the vehicle body, The first front fork is, A first fork body that is extendable and retractable, having a first body-side tube, a first axle-side tube that is movable axially relative to the first body-side tube, a first cap that closes the upper end of the first body-side tube, and a first axle bracket that closes the lower end of the first axle-side tube and holds the axle of the front wheel, The first fork includes a first cylinder connected to the first axle bracket, a first piston rod inserted into the first cylinder so as to be movable in the axial direction and whose upper end is connected to the first cap, and a first piston connected to the first piston rod and inserted into the first cylinder to divide the inside of the first cylinder into a first extension chamber and a first compression chamber, and a first damper which expands and contracts in accordance with the expansion and contraction of the first fork body and generates a damping force that hinders the expansion and contraction of the first fork body, A first reservoir is formed in the space between the first fork body and the first damper to store liquid. The second front fork is A second fork body that is extendable and retractable, having a second body-side tube, a second axle-side tube that is movable axially relative to the second body-side tube, a second cap that closes the upper end of the second body-side tube, and a second axle bracket that closes the lower end of the second axle-side tube and holds the front wheel axle, The second fork has a second cylinder connected to the second axle bracket, a second piston rod inserted into the second cylinder so as to be movable in the axial direction and whose upper end is connected to the second cap, and a second piston connected to the second piston rod and inserted into the second cylinder to divide the inside of the second cylinder into a second extension chamber and a second compression chamber, and a second damper which expands and contracts in accordance with the expansion and contraction of the second fork body and generates a damping force that hinders the expansion and contraction of the second fork body, A second reservoir is formed in the space between the second fork body and the second damper to store liquid. The first damper includes an extension damping force adjustment passage connecting the first extension chamber and the first compression chamber, an extension damping force adjustment valve provided in the middle of the extension damping force adjustment passage, and an extension adjustment section provided on the first cap that can adjust the resistance that the extension damping force adjustment valve imparts to the flow of liquid passing through the extension damping force adjustment passage. The second damper has a compression damping force adjustment passage that communicates with the second compression chamber and the second reservoir through the second piston rod, a compression damping force adjustment valve provided in the middle of the compression damping force adjustment passage, and a compression adjustment section provided in the second cap that can adjust the resistance that the compression damping force adjustment valve imparts to the flow of liquid passing through the compression damping force adjustment passage. The first piston rod and the second piston rod are both cylindrical in shape. The extension damping force adjustment valve has an extension needle that is axially movable inside the first piston rod and an extension annular valve seat provided on the inner circumference of the first piston rod. The compression damping force adjustment valve has a compression needle that is axially movable inserted into the second piston rod and a compression annular valve seat provided on the inner circumference of the second piston rod. The first damper has an extension control rod inserted into the first piston rod and transmitting the power of the extension adjustment section to the extension needle, The second damper has a compression control rod inserted into the second piston rod and transmitting the power of the compression adjustment unit to the compression needle, The first damper and the second damper share common components, except for the first piston rod, the second piston rod, the extension needle, the compression needle, the extension control rod, and the compression control rod. A suspension system characterized by the following features.

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