Front fork

Abstract

The front fork (F) is provided with a telescopic fork main body (1) and a damper (D) which is accommodated in the fork main body (1) and is clamped between a vehicle body side tube (2) and an axle side tube (3). A piston (11) that divides the inside of the cylinder (10) into an extension-side chamber (R1) and a compression-side chamber (R2); a cylindrical piston rod (12) that is connected to a vehicle-body-side tube (2) and that is connected to the piston (11); a first damping force adjustment passage (P1) that is provided inside the piston rod (12) and that connects the extension-side chamber (R1) and a reservoir chamber (R); and a second damping force adjustment passage (P2) that is provided inside the piston rod (12) and that connects the extension-side chamber (R1) and the reservoir chamber (R). The second damping force adjusting channel (P2) is communicated with the compression side cavity (R2), and the first damping force adjusting valve (V1) and the second damping force adjusting valve (V2) are arranged in the piston rod (12).

Description

Technical Field

[0001] The present invention relates to a front fork. Background Art

[0002] A front fork mounted between the body and the front wheel of a two-wheeled motor vehicle is provided with a shock absorber for generating a damping force during telescopic movement in order to suppress vibrations of the body and the front wheel when the two-wheeled motor vehicle is running.

[0003] More specifically, the front fork includes, for example, a fork main body and a shock absorber accommodated in the fork main body. The fork main body includes a body side tube, an axle side tube capable of relatively moving axially with respect to the body side tube, a cap for closing the upper end of the body side tube, and an axle bracket for closing the lower end of the axle side tube and holding the axle of the front wheel.

[0004] In addition, the shock absorber includes: a cylinder fixed at the lower end to the axle bracket; a piston rod having an upper end connected to the cap and inserted into the cylinder; a piston mounted at the front end of the piston rod and slidably inserted into the cylinder to divide the inside of the cylinder into an extension side chamber and a compression side chamber; a valve disk inserted into the lower side inside the cylinder, separating a chamber communicating with a reservoir chamber outside the cylinder through a hole provided in the cylinder from the compression side chamber; an extension side damping passage and a compression side passage provided on the piston; an extension side leaf valve capable of opening or closing the extension side damping passage and applying pressure to hydraulic oil flowing from the extension side chamber to the compression side chamber; a compression side check valve capable of opening or closing the compression side passage and allowing only hydraulic oil to flow from the compression side chamber to the extension side chamber; a compression side damping passage and a suction passage provided on the valve disk; a compression side leaf valve capable of opening or closing the compression side damping passage and applying resistance to the liquid flow from the compression side chamber to the reservoir chamber; an extension side check valve capable of opening or closing the suction port and allowing only hydraulic oil to flow from the reservoir chamber to the compression side chamber.

[0005] In a front fork configured as described above, as shown in Japanese Patent JPH11-201214A or JPH6-56532U, in order to be able to adjust the damping force generated by the shock absorber, on the basis of the above structure, an extension-side damping force adjustment passage that bypasses the extension-side damping passage and connects the extension-side chamber and the compression-side chamber is further provided on the piston rod, an extension-side needle valve provided in the middle of the extension-side damping force adjustment passage, a compression-side damping force adjustment passage provided on the axle bracket and connecting the compression-side chamber and the liquid storage chamber, and a compression-side needle valve provided in the middle of the compression-side damping force adjustment passage. In this front fork, the flow path area of the extension-side needle valve can be adjusted by operating the extension-side adjuster provided on the cover of the fork main body, thereby adjusting the extension-side damping force when the shock absorber extends. At the same time, the flow path area of the compression-side needle valve can be adjusted by operating the compression-side adjuster provided on the axle bracket, thereby adjusting the compression-side damping force when the shock absorber contracts. Prior Art Documents Patent Documents

[0006] Patent Document 1: Japanese Patent JPH11-201214A Patent Document 2: Japanese Patent JPH6-56532U Summary of the Invention Problems to be Solved by the Invention

[0007] In conventional suspension devices, the extension-side damping force and the compression-side damping force of the shock absorbers on each front fork can be adjusted independently. Since the compression-side adjuster is provided on the axle bracket at the lower end of the front fork, in order to adjust the compression-side damping force, the user needs to get off the vehicle and bend down to operate the compression-side adjuster. Thus, in traditional suspension devices, the adjustment of the compression-side damping force is a very troublesome task. Therefore, a suspension device is needed in which not only the adjustment of the extension-side damping force but also the adjustment of the compression-side damping force can be performed on the upper end side of the front fork.

[0008] In addition, considering the case of using an actuator to adjust the compression-side damping force, in conventional suspension devices, the structure is to arrange the actuator in a position close to the ground, so it is not suitable to set an actuator in conventional suspension devices.

[0009] Therefore, an object of the present invention is to provide a front fork capable of adjusting the extension-side damping force and the compression-side damping force on the upper end side of the front fork. Means for Solving the Problems

[0010] In order to solve the above problems, the front fork of the present invention includes a telescopic fork main body having a body side tube and an axle side tube, and a shock absorber accommodated in the fork main body and clamped between the body side tube and the axle side tube; the shock absorber includes: a cylinder connected to the axle side tube; a piston that is inserted into the cylinder so as to be axially movable and divides the interior of the cylinder into an extension side chamber and a compression side chamber; a cylindrical piston rod that is axially movably inserted into the cylinder, with its upper end connected to the body side tube and its lower side connected to the piston; a first damping force adjustment passage provided in the piston rod and communicating the extension side chamber with a liquid storage chamber formed by the space between the fork main body and the shock absorber; a second damping force adjustment passage provided in the piston rod and communicating the extension side chamber and the compression side chamber; a first damping force adjustment valve provided in the piston rod and capable of adjusting the resistance applied to the liquid flow passing through the first damping force adjustment passage; and a second damping force adjustment valve provided in the piston rod and capable of adjusting the resistance applied to the liquid flow passing through the second damping force adjustment passage.

[0011] In the front fork configured as described above, a first damping force adjustment passage that communicates the extension side chamber with the liquid storage chamber and a second damping force adjustment passage that communicates the extension side chamber with the compression side chamber are provided in the piston rod; both the extension side damping force and the compression side damping force can be adjusted by the first damping force adjustment valve and the second damping force adjustment valve in the piston rod. Moreover, since both the first damping force adjustment valve and the second damping force adjustment valve are provided in the piston rod, the first damping force adjustment valve and the second damping force adjustment valve can be operated from the upper end side of the body side tube to which the upper end of the piston rod is connected, so as to adjust the extension side damping force and the compression side damping force. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a cross-sectional view of the front fork according to an embodiment of the present invention. Figure 2 is an enlarged cross-sectional view of the first damping force adjustment valve and the second damping force adjustment valve of the front fork according to an embodiment of the present invention. Figure 3 is an enlarged cross-sectional view of a first modification of the first damping force adjustment valve and the second damping force adjustment valve of the front fork according to an embodiment of the present invention. Figure 4 is an enlarged cross-sectional view of a second modification of the first damping force adjustment valve and the second damping force adjustment valve of the front fork according to an embodiment of the present invention. Figure 5 is an enlarged cross-sectional view of a third modification of the first damping force adjustment valve and the second damping force adjustment valve of the front fork according to an embodiment of the present invention. Figure 6An enlarged cross-sectional view of a fourth modification of the first damping force adjusting valve and the second damping force adjusting valve in the front fork according to an embodiment of the present invention. Detailed implementation mode

[0013] Next, the present invention will be described according to the embodiment shown in the figure. As Figure 1 shown, in one embodiment, the front fork F is composed of a telescopic fork body 1 having a body side tube 2 and an axle side tube 3, and a shock absorber D accommodated in the fork body 1 and sandwiched between the body side tube 2 and the axle side tube 3. Although not shown, the front fork is sandwiched between the body of a suspension straddle vehicle such as a two-wheeled motor vehicle or a three-wheeled vehicle and the front wheel, and is used to suppress vibrations between the body and the front wheel.

[0014] Next, each part of the front fork F will be described in detail. As described above, the front fork F includes the fork body 1 and the shock absorber D accommodated in the fork body 1. The fork body 1 is telescopic and includes a body side tube 2 and an axle side tube 3 that can move axially relative to the body side tube 2. In addition, the fork body 1 includes a cover 4 for closing the upper end of the body side tube 2 and an axle bracket 5 for closing the lower end of the axle side tube 3 and holding the axle of the front wheel, and the inside of the fork body is in a sealed state.

[0015] The cover 4 is cylindrical and includes a large-diameter portion 4a that is threadedly coupled to the inner circumference of the upper end opening of the body side tube 2, and a small-diameter portion 4b that extends downward from the lower end of the Figure 1 and has an outer diameter smaller than that of the large-diameter portion 4a. In addition, an actuator 6 is accommodated in the inner circumference of the large-diameter portion 4a of the cover 4. The actuator 6 includes a stepper motor and a conversion mechanism that converts the rotational motion of a rotor (not shown) of the stepper motor into the axial motion of a linear motion shaft 6a. When the actuator 6 is energized and driven, it can displace the linear motion shaft 6a in the Figure 1 vertical direction within the cover 4.

[0016] The axle side tube 3 is inserted into the body side tube 2 from below the body side tube 2 and can move axially relative to the body side tube 2. In addition, a ring-shaped bushing 7 and a ring-shaped sealing member 8 that are in sliding contact with the outer circumference of the axle side tube 3 are provided on the inner circumference of the lower end of the body side tube 2, and a ring-shaped bushing 9 that is in sliding contact with the inner circumference of the body side tube 2 is installed on the outer circumference of the upper end of the axle side tube 3. Therefore, the body side tube 2 and the axle side tube 3 can move axially relative to each other without axial jitter through the bushings 7 and 9.

[0017] The lower end of the axle side tube 3 is closed by an axle bracket 5 that holds the axle of the front wheel (not shown), and the fork body 1 is connected to the front wheel through the axle bracket 5. Moreover, the interior of the fork body 1 configured in this way forms a sealed space and is sealed from the outside by a sealing member 8. The axle bracket 5 includes a bottomed cylindrical tubular portion 5a that is cylindrical and threadedly connected to the outer periphery of the lower end of the axle side tube 3, and a holding portion 5b that is connected to the bottom of the tubular portion 5a and holds the axle (not shown). In addition, although not shown, the axle bracket 5 is provided with mounting portions for mounting a brake caliper, a fender, etc.

[0018] In addition, in the front fork F of the present embodiment, the fork body 1 is configured as an inverted type in which the axle side tube 3 is inserted into the body side tube 2, but it may also be configured as an upright type in which the body side tube 2 is inserted into the axle side tube 3.

[0019] The shock absorber D includes: a cylinder 10 connected to the axle side tube 3 through the axle bracket 5; a piston 11 that is inserted into the cylinder 10 so as to be movable along the axial direction and divides the interior of the cylinder 10 into an extension side chamber R1 filled with liquid and a compression side chamber R2; a cylindrical piston rod 12 that is inserted into the cylinder 10 so as to be axially movable and whose upper end is connected to the body side tube 2 through a cover 4 and whose lower side is connected to the piston 11; a first damping force adjustment passage P1 that is provided in the piston rod 12 and connects the extension side chamber R1 and a liquid storage chamber R formed by the space between the fork body 1 and the shock absorber D; a second damping force adjustment passage P2 that is provided in the piston rod 12 and connects the extension side chamber R1 and the compression side chamber R2; a first damping force adjustment valve V1 that is provided in the piston rod 12 and can adjust the resistance applied to the liquid flow passing through the first damping force adjustment passage P1; a second damping force adjustment valve V2 that is provided in the piston rod 12 and can adjust the resistance applied to the liquid flow passing through the second damping force adjustment passage. Further, in the front fork F of the present embodiment, the shock absorber D includes: a compression side passage 11a and an extension side damping passage 11b for connecting the extension side chamber R1 and the compression side chamber R2, a compression side check valve 13 provided on the compression side passage 11a, an extension side damping valve 14 provided on the extension side damping passage 11b, a compression side damping passage 16a and a suction passage 16b that connect the compression side chamber R2 and the liquid storage chamber R, a compression side damping valve 17 provided on the compression side damping passage 16a, and a suction check valve 18 provided on the suction passage 16b. Moreover, the shock absorber D is accommodated in the fork body 1, and a liquid storage chamber R storing liquid is formed inside the fork body 1 and outside the shock absorber D.

[0020] Next, each part of the shock absorber D will be described. The cylinder 10 is connected to the axle bracket 5 through a bottom valve assembly 15 fixed to the axle bracket 5 of the fork body 1. The cylinder 10 has a through hole 10a that opens from the side of the lower end and communicates the inside of the cylinder 10 with the liquid storage chamber R. In addition, a ring-shaped guide member 20 is installed at the open end of the upper end of the cylinder 10. The guide member 20 has a guide portion 20a that is ring-shaped and slidably contacts the outer periphery of the piston rod 12 inserted into the inner periphery by being threadedly engaged with the inner periphery of the upper end of the cylinder 10, and a cylindrical housing portion 20b that protrudes upward from the upper end of the guide portion 20a. In addition, the liquid filled in the cylinder 10 and the liquid storage chamber R is hydraulic oil, but it can also be a liquid other than hydraulic oil.

[0021] The bottom valve assembly 15 includes a ring-shaped partition body 16 fitted above the through hole 10a of the cylinder 10, and a holding member 19 fixed to the axle bracket 5 by a bolt 21 passing through the bottom of the cylindrical portion 5a of the axle bracket 5 and screwed to the lower end of the cylinder 10 for holding the partition body 16. The holding member 19 has a closing portion 19a that is located at the lower end of the cylinder 10 and is screwed to the inner periphery below the through hole 10a to close the lower end of the cylinder 10, and a shaft portion 19b that protrudes upward from the closing portion 19a and has the partition body 16 mounted on its outer periphery. In this way, the space between the partition body 16 and the closing portion 19a inside the cylinder 10 communicates with the liquid storage chamber R through the through hole 10a, and the partition body 16 divides the inside of the cylinder 10 into a compression side chamber R2 and a space communicating with the liquid storage chamber R.

[0022] In addition, a compression side damping passage 16a and a suction passage 16b that communicate the compression side chamber R2 with the liquid storage chamber R via the space are provided on the partition body 16. Moreover, a compression side damping valve 17 for applying resistance to the liquid flow from the compression side chamber R2 to the liquid storage chamber R is provided on the compression side damping passage 16a, and a suction check valve 18 that only allows the liquid to flow from the liquid storage chamber R to the compression side chamber R2 is provided on the suction passage 16b.

[0023] The piston rod 12 includes a cylindrical piston rod main body 22, a cylindrical center rod 23 that is threadedly coupled to the lower end of the piston rod main body 22 and is used to hold the piston 11, and a cylindrical collar 24 that is clamped between the piston rod main body 22 and the center rod 23 as a second stopper. And the piston rod 12, its upper end is threadedly coupled and connected to the inner periphery of the small diameter portion 4b of the cover 4, and its lower end side passes through the inner periphery of the guide member 20 and is inserted into the cylinder 10. The piston rod 12 can move relatively in the axial direction, that is, Figure 1 in the up and down direction, together with the piston 11 in a state where the radial movement relative to the cylinder 10 is restricted by the guide member 20 and the piston 11.

[0024] As Figure 1 and Figure 2As shown, the piston rod body 22 is cylindrical and Figure 1 As shown, its upper end is threadedly connected to the small diameter portion 4b of the cover 4, and a horizontal hole 22a is provided in the middle portion which is opened from the side and communicates with the inside, and as shown in FIG. Figure 2 As shown, a threaded portion 22b is provided on the outer periphery of the lower end.

[0025] In addition, the center rod 23 has the following features: Figure 1 and Figure 2 The sleeve 23a shown is a cylindrical sleeve 23a that is threadedly coupled to the outer periphery of the threaded portion 22b of the piston rod body 22, and the sleeve 23a. Figure 2 The middle and lower ends are connected and the inner diameter is smaller than the inner diameter of the sleeve 23a and Figure 2 The valve accommodating portion 23b is a cylindrical valve accommodating portion 23b having a stepped portion on the inner circumference and a narrowed middle and lower end side. Figure 2 A tubular piston mounting portion 23c extending downward at the lower and middle end and having an outer diameter smaller than that of the valve accommodating tube 23b and on the outer periphery of which the piston 11 is mounted; a port 23d opening on the side of the valve accommodating tube 23b facing the extension side chamber R1 and communicating with the piston rod body side rather than the step portion of the valve accommodating tube 23b; and a second annular valve seat 23e formed by the step portion and arranged on the inner periphery of the valve accommodating tube 23b.

[0026] The collar 24 is cylindrical and has a Figure 2 The flange 24a on the outer periphery of the lower end of the piston rod 12 and the large-diameter inner periphery 24b set to enlarge the inner diameter of the inner periphery of the lower end. The collar 24 is inserted into the sleeve 23a of the center rod 23 from the flange 24a side. When the threaded portion 22b of the piston rod body 22 is threadedly engaged with the inner periphery of the sleeve 23a, the flange 24a is clamped by the piston rod body 22 and the upper end of the valve accommodating tube 23b and fixed to the piston rod body 22 and the center rod 23. The piston rod 12 constructed in this way is cylindrical as a whole because the piston rod body 22, the center rod 23 and the collar 24 are cylindrical. In addition, since the opening portion as the front end, i.e., the lower end of the piston rod 12 faces the compression side chamber R2, the interior of the piston rod 12 is connected to the compression side chamber R2, is connected to the liquid storage chamber R through the horizontal hole 22a, and is connected to the extension side chamber R1 through the port 23d.

[0027] Moreover, the port 23d of the piston rod 12, the transverse hole 22a, and the portion from the port 23d in the piston rod 12 to the transverse hole 22a form a first damping force adjustment channel P1 connecting the extension side chamber R1 and the liquid storage chamber R, and the port 23d of the piston rod 12 and the portion from the port 23d in the piston rod 12 to the lower end opening form a second damping force adjustment channel P2 connecting the extension side chamber R1 and the compression side chamber R2.

[0028] In addition, on the outer periphery of the piston rod body 22 and closer to the horizontal hole 22a Figure 1A ring-shaped locking member 26 is provided at the lower middle part and enters the housing part 20b of the guide member 20 when the shock absorber D contracts to the limit. The housing part 20b and the locking member 26 form a hydraulic buffer device. Once the locking member 26 enters the housing part 20b, the hydraulic buffer device raises the pressure inside the housing part 20b to inhibit further contraction of the shock absorber D. A suspension spring 51 is clamped between the housing part 20b of the guide member 20 and a cylindrical spring seat 50 mounted on the outer periphery of the small-diameter part 4b of the cover 4, and it applies a force to the fork body 1 in a direction that always makes it extend. Therefore, when the front fork F is clamped between the vehicle body and the front wheel, the front fork F exerts the elastic force of the suspension spring 51 to elastically support the vehicle body. In addition, even when the locking member 26 enters the housing part 20b, the horizontal hole 22a is located outside the space surrounded by the housing part 20b and the locking member 26 and remains in communication with the liquid storage chamber R. Therefore, the hydraulic buffer device does not apply resistance to the liquid flow flowing through the first damping force adjustment passage P1.

[0029] The piston 11 is ring-shaped and is fitted on the outer periphery of a piston mounting portion 23c at the front end of the lower middle part of a central rod 23 provided on the piston rod 12, and is clamped and fixed to the piston mounting portion 23c by the lower end of a valve receiving cylinder 23b and a piston nut 25 screwed to the lower end of the piston mounting portion 23c. In addition, the piston 11 is in contact with the inner periphery of the cylinder 10 and divides the inside of the cylinder 10 into an extension side chamber R1 and a compression side chamber R2. In addition, the piston 11 is provided with a compression side passage 11a and an extension side damping passage 11b that connect the extension side chamber R1 and the compression side chamber R2 in parallel. Figure 2 On the outer periphery of the piston mounting portion 23c at the front end of the lower middle part of the central rod 23 provided on the piston rod 12, and is clamped and fixed to the piston mounting portion 23c by the lower end of the valve receiving cylinder 23b and the lower end of the piston nut 25 screwed to the piston mounting portion 23c. Figure 2 Moreover, the piston 11 is in contact with the inner periphery of the cylinder 10 and divides the inside of the cylinder 10 into an extension side chamber R1 and a compression side chamber R2. In addition, the piston 11 is provided with a compression side passage 11a and an extension side damping passage 11b that connect the extension side chamber R1 and the compression side chamber R2 in parallel.

[0030] A compression side valve seat that surrounds the outer periphery of the compression side passage 11a is provided on the extension side chamber side end of the piston 11. In addition, a compression side check valve 13 is provided on the extension side chamber side of the piston 11. The compression side check valve can be disengaged from and seated on the compression side valve seat to open or close the compression side passage 11a, and only allows liquid to flow from the compression side chamber R2 to the extension side chamber R1 through the compression side passage 11a. The compression side check valve 13 includes an annular plate that is axially movably mounted on the outer periphery of the piston mounting portion 23c and can be disengaged from and seated on the compression side valve seat, a spring seat mounted on the outer periphery of the piston mounting portion 23c, and a spring that is clamped between the annular plate and the spring seat in a compressed state and applies a force to the annular plate toward the piston 11 side. Moreover, when the annular plate is compressed by the pressure in the compression side chamber R2 through the compression side passage 11a and compresses the spring and then separates from the compression side valve seat, the compression side check valve 13 opens the compression side passage 11a, and when the annular plate is seated on the compression side valve seat, it cuts off the compression side passage 11a. Therefore, the compression side check valve 13 sets the compression side passage 11a as a one-way passage that only allows liquid to flow from the compression side chamber R2 to the extension side chamber R1.

[0031] An extension side valve seat 11d surrounding the outer periphery of the extension side damping passage 11b is provided at the compression side chamber end of the piston 11, and an extension side damping valve 14 is also stacked, which can be seated on the extension side valve seat 11d to open or close the extension side damping passage 11b, and only allows the liquid to flow from the extension side chamber R1 to the compression side chamber R2 through the extension side damping passage 11b and applies resistance to the liquid. The extension side damping valve 14 is a stacked leaf valve composed of a plurality of annular leaf valves stacked, and its inner periphery is fixed to the piston mounting portion 23c together with the piston 11 by the piston nut 25, allowing the outer periphery to bend.

[0032] Therefore, when the expansion-side damping valve 14 is bent on the outer peripheral side by the pressure of the expansion-side chamber R1 acting through the expansion-side damping passage 11b and leaves the expansion-side valve seat 11d, the expansion-side damping passage 11b is opened to apply resistance to the flow of the liquid passing therethrough, and the expansion-side damping passage 11b is blocked in the state of being seated on the expansion-side valve seat 11d. Therefore, the expansion-side damping valve 14 sets the expansion-side damping passage 11b as a one-way passage that allows only the liquid to flow from the expansion-side chamber R1 to the compression-side chamber R2.

[0033] Next, the first damping force adjustment valve V1 is provided in the piston rod 12. More specifically, in the front fork F of the present embodiment, the first damping force adjustment valve V1 is a needle valve and has a needle valve inserted into the piston rod body 22 so as to be movable in the axial direction. Figure 2 The first valve needle 30 on the inner side of the middle lower end side is formed on the shaft ring 24. Figure 2 A first annular valve seat 31 around the opening at the middle upper end and a control rod 32 are inserted into the piston rod body 22 axially movably and transmit the thrust of the linear motion shaft 6 a of the actuator 6 to the valve needle 30 .

[0034] like Figure 2 As shown, the first valve needle 30 includes a head 30a which is inserted into the shaft ring 24 axially movably and has a conical surface on the outer circumference, and a Figure 2 The middle and upper ends are connected and can make Figure 2 The first valve needle 30 is inserted into the piston rod body 22 so as to be movable in the axial direction and can be close to or away from the first annular valve seat 31. In addition, when the main body 30b is moved in the axial direction, the first valve needle 30 can be moved in the axial direction. Figure 2 When the outer periphery of the middle and lower end is seated on the first annular valve seat 31, the valve needle 30 closes the first damping force adjustment passage P1, and cuts off the communication between the extension side chamber R1 and the liquid storage chamber R via the first damping force adjustment passage P1.Figure 2 In a state where the outer periphery of the lower-middle part is separated from the first annular valve seat 31, the first valve needle 30 generates a gap between the outer periphery formed by the conical surface of the head 30a and the inner periphery of the first annular valve seat 31 to open the first damping force adjustment passage P1, and the extension side chamber R1 and the liquid storage chamber R are communicated through the first damping force adjustment passage P1. In addition, when the Figure 2 outer periphery of the lower-middle part is separated from the first annular valve seat 31, if the first valve needle 30 generates an axial displacement relative to the first annular valve seat 31, the size of the gap between the head 30a and the inner periphery of the first annular valve seat 31 can be changed according to the position relative to the first annular valve seat 31, so that the resistance applied to the liquid flow passing through the first damping force adjustment valve V1 can be adjusted in size.

[0035] In addition, since the guide portion 30c is in sliding contact with the inner periphery of the piston rod main body 22, the first valve needle 30 can move axially within the piston rod 12 without generating axial jitter. Further, a notch 30d is provided on the outer periphery of the guide portion 30c of the first valve needle 30, so that the first damping force adjustment passage P1 is not blocked by the guide portion 30c.

[0036] The control rod 32 is cylindrical and is axially movably inserted into the piston rod main body 22, and has a lower hole 32a provided near the lower end and an upper hole 32b opened near the position where the piston rod main body 22 is provided with the horizontal hole 22a. Therefore, the inside and outside of the control rod 32 are communicated through the lower hole 32a and the upper hole 32b. The Figure 2 lower-middle part of the control rod 32 abuts against the Figure 2 upper-middle part of the guide portion 30c of the first valve needle 30. However, since the outer diameter of the control rod 32 is smaller than the outer diameters of the piston rod main body 22 and the guide portion 30c, the notch 30d is not closed, ensuring that the extension side chamber R1 and the liquid storage chamber R are communicated via the first damping force adjustment passage P1. In addition, in the front fork F of the present embodiment, since the control rod 32 is cylindrical and has the lower hole 32a and the upper hole 32b, the inside of the control rod 32 also functions as a part of the first damping force adjustment passage P1. Therefore, even when the control rod 32 is inserted into the piston rod main body 22, there is a sufficiently large flow path area to ensure that the flow of the liquid is not hindered.

[0037] The control rod 32 configured as such is clamped between the first valve needle 30 and the linear motion shaft 6a of the actuator 6, and can transmit the thrust of the actuator 6 to the first valve needle 30. Therefore, by adjusting the thrust of the actuator 6, the first valve needle 30 can adjust the flow path area of the first damping force regulating valve V1, thereby adjusting the magnitude of the resistance applied to the liquid flow passing through the first damping force regulating valve V1, and can close the first damping force regulating valve V1 to cut off the first damping force regulating passage P1. In addition, the head 30a of the first valve needle 30 of the first damping force regulating valve V1 is set to a shape most suitable for the flow rate of the liquid flowing through the first damping force regulating passage P1 when the shock absorber D performs a contraction action. Furthermore, the first damping force regulating valve V1 is arranged at a position always below the liquid level O of the liquid stored in the liquid storage chamber R even when the shock absorber D extends to the limit and the piston rod 12 moves maximally upward from the cylinder 10 to Figure 1 the upper middle.

[0038] Next, the second damping force regulating valve V2 is arranged in series with the first damping force regulating valve V1 axially in the piston rod 12. More specifically, in the front fork F of the present embodiment, the second damping force regulating valve V2 is a needle valve and includes a second valve needle 33 and a second spring 34. The second valve needle 33 is inserted into the valve receiving cylinder 23b of the center rod 23 that forms a part of the second damping force regulating passage P2 in a manner capable of moving axially. The second spring 34 is arranged on the second annular valve seat 23e on the inner periphery of the valve receiving cylinder 23b of the center rod 23, and is clamped between the valve receiving cylinder 23b and the second valve needle 33 and biases the second valve needle 33 in a direction away from the second annular valve seat 23e.

[0039] As Figure 2 shown, the second valve needle 33 includes: a head 33a having a conical surface on its outer periphery, which is axially movably inserted into the inner periphery of the valve receiving cylinder 23b, and the diameter of the receiving cylinder is smaller below the second annular valve seat 23e; a cylindrical main body portion 33b, which is connected to the Figure 2 upper middle end of the head 33a and can oppose the Figure 2 lower end to the second annular valve seat 23e and seat thereon; a flange-shaped guiding portion 33c, which is arranged on the Figure 2 outer periphery of the upper middle end of the main body portion 33b and is in sliding contact with the inner periphery of the valve receiving cylinder 23b; a transmission shaft 33d, which extends upward from the rear end of the guiding portion 33c, that is, the Figure 2 upper middle end, and is inserted into the collar 24, and the transmission shaft is opposed to the front end of the first valve needle 30. In addition, the outer diameter of the transmission shaft 33d is smaller than the inner diameter of the collar 24, and an annular gap allowing liquid to pass through is formed between the outer periphery of the transmission shaft 33d and the inner periphery of the collar 24.

[0040] When theFigure 2 When the outer periphery of the middle and lower end is seated on the second annular valve seat 23e, the second valve needle 33 closes the lower side of the opening of the port 23d of the center rod 23, thereby cutting off the communication between the extension side chamber R1 and the compression side chamber R2 communicated by the second damping force adjustment passage P2. In addition, when the Figure 2 outer periphery of the middle and lower end of the main body portion 33b is separated from the second annular valve seat 23e, the second valve needle 33 forms a gap between the outer peripheral surface formed by the conical surface of the head 33a and the inner periphery of the second annular valve seat 23e to open the second damping force adjustment passage P2, and the extension side chamber R1 and the compression side chamber R2 are communicated through the second damping force adjustment passage P2. In addition, when the Figure 2 outer periphery of the middle and lower end of the main body portion 33b is separated from the second annular valve seat 23e, when the second valve needle 33 generates an axial displacement relative to the second annular valve seat 23e, the size of the gap between the head 33a and the inner periphery of the second annular valve seat 23e can be changed according to the position relative to the second annular valve seat 23e, so that the resistance applied to the liquid flow passing through the second damping force regulating valve V2 can be adjusted in size.

[0041] In addition, since the guiding portion 33c is in sliding contact with the inner periphery of the valve receiving cylinder 23b of the center rod 23, the second valve needle 33 can move axially within the center rod 23 without generating axial jitter. In addition, a notch 33e is provided on the outer periphery of the guiding portion 33c of the second valve needle 33, so that the second damping force adjustment passage P2 is not blocked by the guiding portion 33c.

[0042] The second spring 34 is clamped in a compressed state between the guiding portion 33c of the second valve needle 33 and the stepped portion of the inner periphery of the valve receiving cylinder 23b, and always applies a force to the second valve needle 33 in the direction away from the second annular valve seat 23e along the axial direction. When the second valve needle 33 is not subjected to any force other than the acting force of the second spring 34, due to the acting force of the second spring 34, it is positioned at the Figure 2 position where the upper middle end of the guiding portion 33c abuts against the Figure 2 lower middle end of the collar 24. Even if the upper end of the guiding portion 33c abuts against the lower end of the collar 24, since the large-diameter inner peripheral portion 24b of the collar 24 and the notch 33e of the guiding portion 33c are opposed to each other, the second damping force adjustment passage P2 is not blocked by the second valve needle 33 and the collar 24.

[0043] In addition, since the second spring 34 applies a force to the second valve needle 33 toward the first valve needle 30 side in the first damping force regulating valve V1, the transmission shaft 33d at the rear end of the second valve needle 33 abuts against the front end of the first valve needle 30, and transmits the acting force of the second spring 34 to the first valve needle 30. Thus, the second valve needle 33 and the first valve needle 30 are arranged in series along the axial direction in the piston rod 12 and abut against each other. Therefore, when the actuator 6 is driven to move the linear motion shaft 6a in theFigure 2 When the piston rod moves axially up and down, the power of the actuator 6 is transmitted to the first valve needle 30 through the control rod 32, causing the first valve needle 30 to move up and down. The power of the actuator 6 is also transmitted to the second valve needle 33 through the first valve needle 30, causing the second valve needle 33 to move up and down together with the first valve needle 30.

[0044] Moreover, in a state where the front end of the first valve needle 30 abuts against the rear end of the transmission shaft 33d of the second valve needle 33, in the axial direction of the piston rod 12, the distance between the lower end of the main body portion 30b of the first valve needle 30 and the lower end of the main body portion 33b of the second valve needle 33 is equal to the axial distance between the first annular valve seat 31 and the second annular valve seat 23e. Therefore, when the actuator 6 is driven to seat the main body portion 30b of the first valve needle 30 on the first annular valve seat 31 and close the first damping force regulating valve V1 to cut off the first damping force regulating passage P1, the second valve needle 33 also moves downward in the center rod 23 against the acting force of the second spring 34 Figure 2 and seat the main body portion 33b on the second annular valve seat 23e and close the second damping force regulating valve V2 to cut off the second damping force regulating passage P2.

[0045] On the other hand, when the first valve needle 30 is separated from the first annular valve seat 31, the first damping force regulating valve V1 opens, so that the first damping force regulating passage P1 is opened. The second valve needle 33 also separates from the second annular valve seat 23e due to the acting force of the second spring 34, and the second damping force regulating valve V2 opens, so as to open the second damping force regulating passage P2. Moreover, in a state where the first damping force regulating valve V1 and the second damping force regulating valve V2 are opened, the first valve needle 30 and the second valve needle 33 are positioned at a position where the thrust applied by the actuator 6 to the first damping force regulating valve V1 and the second damping force regulating valve V2 is balanced with the acting force of the second spring 34. Therefore, in a state where the first damping force regulating valve V1 and the second damping force regulating valve V2 are opened, the opening degrees of the first damping force regulating valve V1 and the second damping force regulating valve V2 can be adjusted by adjusting the magnitude of the thrust applied by the actuator 6 to the first damping force regulating valve V1 and the second damping force regulating valve V2. In addition, when the rear end of the guiding portion 33c abuts against the collar 24, the second valve needle 33 is positioned at its upper limit position, and the maximum flow path area of the second damping force regulating valve V2 can be limited because its further separation from the second annular valve seat 23e is restricted. Therefore, when the first valve needle 30 moves in the piston rod 12 Figure 2When moving upward and centerward, when the displacement of the first valve needle 30 exceeds the upper limit of the stroke of the second valve needle 33, the first valve needle 30 and the transmission shaft 33d are separated, positioning the second valve needle 33 at the upper limit position. Thus, the maximum flow path area of the second damping force regulating valve V2 can be set by providing a collar 24, which, when in contact with the second valve needle 33, can act as a second stopper to limit the separation of the second valve needle 33 from the second annular valve seat 23e. In addition, by using the collar 24 formed with the first annular valve seat 31 as the second stopper, the number of components can be reduced, but a second stopper can also be provided separately within the center rod 23. Further, in the front fork F of the present embodiment, by providing the collar 24 formed with the first annular valve seat 31, the assembly of the second damping force regulating valve V2 within the center rod 23, the provision of the second stopper on the second valve needle 33, and the provision of the first annular valve seat 31 in the first damping force regulating valve V1 can be simplified.

[0046] Thus, in the front fork F of the present embodiment, the power of the actuator 6 can be transmitted to the second damping force regulating valve V2 through the first damping force regulating valve V1, and the operation of the second damping force regulating valve V2 can be linked with that of the first damping force regulating valve V1, enabling adjustment of the magnitude of the resistance applied to the liquid flow passing through the first damping force regulating valve V1 and the second damping force regulating valve V2.

[0047] In addition, the shape of the head 30a of the first valve needle 30 of the first damping force regulating valve V1 is set to be most suitable for the flow rate of the liquid flowing through the first damping force regulating passage P1 when the shock absorber D performs an extending operation. Further, similar to the first damping force regulating valve V1, the second damping force regulating valve V2 is provided at a position always below the liquid level O of the liquid stored in the liquid storage chamber R even when the shock absorber D extends to the limit and the piston rod 12 moves upward and centerward to the maximum extent within the cylinder 10. Figure 1 When moving upward and centerward to the maximum extent, it is always located at a position lower than the liquid level O of the liquid stored in the liquid storage chamber R.

[0048] The structure of the front fork F is as described above. Next, the operation of the front fork F will be described. First, when the front fork F extends, the shock absorber D extends together with the fork main body 1. When the shock absorber D extends, the piston 11 moves within the cylinder 10 Figure 1It moves upward and centerward, reducing the elongation-side chamber R1 and expanding the compression-side chamber R2. Then, the liquid pushes open the elongation-side damping valve 14 of the piston 11 and moves from the elongation-side chamber R1 to the compression-side chamber R2 through the elongation-side damping passage 11b. When the liquid passes through the elongation-side damping valve 14, it encounters resistance, so the pressure in the elongation-side chamber R1 rises. In addition, when the first valve needle 30 of the first damping force regulating valve V1 separates from the first annular valve seat 31 and the first damping force regulating valve V1 opens, the liquid in the elongation-side chamber R1 flows through the elongation-side damping passage 11b to the compression-side chamber R2. Further, it also flows through the first damping force regulating valve V1 and the first damping force regulating passage P1 to the liquid storage chamber R. Further, in the front fork F of the present embodiment, since the second damping force regulating valve V2 is interlocked with the first damping force regulating valve V1 and also opens when the first damping force regulating valve V1 opens, the liquid in the elongation-side chamber R1 flows through the second damping force regulating valve V2 and the second damping force regulating passage P2 to the compression-side chamber R2 in addition to the elongation-side damping passage 11b. Therefore, when the front fork F performs an elongation operation and the first damping force regulating valve V1 and the second damping force regulating valve V2 open, a liquid flow rate equal to the reduction amount of the volume of the elongation-side chamber R1 passes through the elongation-side damping valve 14, the first damping force regulating valve V1, and the second damping force regulating valve V2, and the elongation-side damping valve 14, the first damping force regulating valve V1, and the second damping force regulating valve V2 apply resistance to the passing liquid flow.

[0049] In addition, when the front fork F performs an elongation operation, the piston rod 12 withdraws from the cylinder 10. Therefore, a shortage of liquid occurs in the expanded compression-side chamber R2, and the amount is equal to the volume of the piston rod 12 withdrawn from the cylinder 10. The liquid in the shortage part is supplied from the liquid storage chamber R to the compression-side chamber R2 through the suction passage 16b due to the opening of the suction check valve 18. Therefore, the pressure in the compression-side chamber R2 is approximately equal to the pressure in the liquid storage chamber R.

[0050] In this way, when the front fork F performs an elongation operation, the pressure in the elongation-side chamber R1 rises to be higher than the pressure in the compression-side chamber R2 and acts on the piston 11, and the shock absorber D generates an elongation-side damping force that hinders the elongation of the front fork F.

[0051] The first damping force regulating valve V1 in the first damping force regulating passage P1 and the second damping force regulating valve V2 in the second damping force regulating passage P2 can be interlocked by the thrust regulation of the actuator 6, and the resistance applied to the liquid flow passing through them can be adjusted in magnitude. Therefore, the pressure magnitude of the extension side chamber R1 of the shock absorber D when the front fork F performs an extension action can be adjusted. Accordingly, the magnitude of the extension side damping force generated by the shock absorber D when the front fork F performs an extension action can be adjusted. If the first damping force regulating valve V1 and the second damping force regulating valve V2 are closed, both the first damping force regulating passage P1 and the second damping force regulating passage P2 are cut off. Therefore, the liquid in the extension side chamber R1 only passes through the extension side damping valve 14, and the extension side damping force can be adjusted to the maximum. Thus, when the front fork F performs an extension action, by using one actuator 6, the resistance applied by the first damping force regulating valve V1 and the second damping force regulating valve V2 to the liquid flow can be adjusted in magnitude. Therefore, the magnitude of the extension side damping force of the front fork F can be adjusted. In addition, in the present embodiment, when the first damping force regulating valve V1 and the second damping force regulating valve V2 are closed, the first damping force regulating passage P1 and the second damping force regulating passage P2 can be completely cut off. Therefore, the maximum value of the damping force generated when the front fork F performs an extension action can be increased. Further, when the second valve needle 33 abuts against the collar 24 serving as the second stopper, the flow path area of the second damping force regulating valve V2 does not increase further. Therefore, it is possible to avoid a situation where the damping force is insufficient when reducing the extension side damping force of the front fork F.

[0052] Next, when the front fork F performs a contraction action, the shock absorber D contracts together with the fork main body 1. When the shock absorber D contracts, the piston 11 moves downward in the middle in the cylinder 10 Figure 1 to reduce the compression side chamber R2 and expand the extension side chamber R1. Then, the liquid causes the compression side check valve 13 to separate from the compression side valve seat and causes the entire compression side check valve 13 to withdraw from the piston 11, and moves from the compression side chamber R2 to the extension side chamber R1 through the compression side passage 11a.

[0053] In addition, since the piston rod 12 enters the cylinder 10, there is excess liquid in the cylinder 10, and the amount of the liquid is equal to the volume of the piston rod 12 entering the cylinder 10. This excess liquid pushes the compression side damping valve 17 and moves from the compression side chamber R2 to the liquid storage chamber R through the compression side damping passage 16a. However, when the first damping force adjusting valve V1 is opened, the liquid moves from the cylinder 10 to the liquid storage chamber R through the first damping force adjusting passage P1 in addition to the compression side damping passage 16a. In addition, when the first damping force adjusting valve V1 is opened, the second damping force adjusting valve V2 is opened in conjunction with the first damping force adjusting valve V1. However, when the shock absorber D performs a contraction action, the compression side check valve 13 is opened and the compression side chamber R2 and the extension side chamber R1 are in a communicating state, and the second damping force adjusting valve V2 becomes a resistance, so that the liquid hardly passes through the second damping force adjusting passage P2.

[0054] Thus, when the front fork F is contracting, when the compression side damping valve 17 or the first damping force regulating valve V1 is opened, the first damping force regulating valve V1 applies resistance to the flow of liquid from the cylinder 10 to the liquid storage chamber R together with the compression side damping valve 17, and the extension side chamber R1 and the compression side chamber R2 are in a communicating state through the compression side passage 11a, so the pressures of the extension side chamber R1 and the compression side chamber R2 rise by substantially the same amount. Moreover, the pressure of the extension side chamber R1 acts on the upper surface of the piston 11, and the pressure of the compression side chamber R2 acts on the lower surface of the piston 11. However, since the piston 11 is connected to the piston rod 12, the pressure receiving area of ​​the lower surface of the piston 11 becomes larger than the pressure receiving area of ​​the upper surface, and the shock absorber D generates the compression side damping force that hinders the contraction of the front fork F.

[0055] In this way, when the front fork F performs a contraction action and the first damping force regulating valve V1 is opened, the compression side damping valve 17 and the first damping force regulating valve V1 are used to increase the pressure of the cylinder 10, and the front fork F generates a compression side damping force. The compression side damping force can be adjusted by adjusting the resistance applied by the first damping force regulating valve V1 to the liquid flow passing through the actuator 6. In addition, when the front fork F performs a contraction action and the first damping force regulating valve V1 is closed, the liquid in the cylinder 10 can no longer pass through the first damping force regulating passage P1, and only moves to the liquid storage chamber R through the compression side damping valve 17. Therefore, when the front fork F performs a contraction action and the first damping force regulating valve V1 is closed, the front fork F generates a larger compression side damping force than when the first damping force regulating valve V1 is opened. As can be understood from the above, in the front fork F of this embodiment, the magnitude of the compression side damping force generated by the front fork F can be adjusted by the first damping force regulating valve V1.

[0056] Among them, in the front fork F of the present embodiment, its structure is such that the fork body 1 receives the lateral force acting on the front fork F. Therefore, the piston rod 12 only needs to have the strength to withstand the damping force generated by the shock absorber D in the axial direction. Since reducing the outer diameter of the piston rod 12 can both reduce the weight of the front fork F and lower the cost, the outer diameter of the piston rod 12 should be made as small as possible. Therefore, when the first damping force regulating valve V1 and the second damping force regulating valve V2 are opened, when the front fork F performs an extending action, the flow rate of the liquid discharged from the extending side chamber R1 through the first damping force regulating passage P1 and the second damping force regulating passage P2 is greater than the flow rate of the liquid passing through the first damping force regulating passage P1 when the front fork F performs a contracting action. The first damping force regulating valve V1 is designed such that the shape of the head 30a of the first valve needle 30 applies an appropriate resistance to the liquid flow rate when the front fork F performs a contracting action. Therefore, it is possible to apply a resistance suitable for a small liquid flow rate when the front fork F performs a contracting action, thereby increasing the adjustment range of the compression side damping force. Since the first damping force regulating valve V1 is set to apply an appropriate resistance to a small liquid flow rate when the front fork F performs a contracting action, if all the liquid flow rate passing through the first damping force regulating passage P1 and the second damping force regulating passage P2 when the front fork F performs an extending action passes through the first damping force regulating valve V1, the resistance in the first damping force regulating valve V1 will become too large, and the adjustment range of the extending side damping force of the front fork F will become smaller. However, in the front fork F of the present embodiment, when the front fork F performs an extending action and the first damping force regulating valve V1 and the second damping force regulating valve V2 are opened, the liquid flows not only through the first damping force regulating valve V1 but also through the second damping force regulating valve V2, which can reduce the liquid flow rate passing through the first damping force regulating valve V1 and increase the decrease range of the extending side damping force. Therefore, in the front fork F of the present embodiment, both the compression side damping force and the extending side damping force can be adjusted, and the adjustment ranges of the compression side damping force and the extending side damping force can be increased.

[0057] As described above, the front fork F of the present embodiment includes a fork main body 1 having a body side tube 2 and an axle side tube 3 that can be telescoped, and a shock absorber D accommodated in the fork main body 1 and sandwiched between the body side tube 2 and the axle side tube 3. The shock absorber D includes: a cylinder 10 connected to the axle side tube 3; a piston 11 that is axially movably inserted into the cylinder 10 and divides the interior of the cylinder 10 into an extension side chamber R1 and a compression side chamber R2; a cylindrical piston rod 12 that is axially movably inserted into the cylinder 10, the upper end of which is connected to the body side tube 2 and the lower side of which is connected to the piston 11; a first damping force adjustment passage P1 provided in the piston rod 12 and communicating the extension side chamber R1 with a reservoir chamber R formed by the space between the fork main body 1 and the shock absorber D; a second damping force adjustment passage P2 provided in the piston rod 12 and communicating the extension side chamber R1 and the compression side chamber R2; a first damping force adjustment valve V1 provided in the piston rod 12 and capable of adjusting the resistance applied to the liquid flow passing through the first damping force adjustment passage P1; and a second damping force adjustment valve V2 provided in the piston rod 12 and capable of adjusting the resistance applied to the liquid flow passing through the second damping force adjustment passage P2.

[0058] In the front fork F configured as described above, a first damping force adjustment passage P1 that communicates the extension side chamber R1 with the reservoir chamber R and a second damping force adjustment passage P2 that communicates the extension side chamber R1 with the compression side chamber R2 are provided in the piston rod 12; both the extension side damping force and the compression side damping force can be adjusted by the first damping force adjustment valve V1 and the second damping force adjustment valve V2 in the piston rod 12. Moreover, since both the first damping force adjustment valve V1 and the second damping force adjustment valve V2 are provided in the piston rod 12, the first damping force adjustment valve V1 and the second damping force adjustment valve V2 can be operated by the actuator 6, so that the extension side damping force and the compression side damping force can be adjusted, and the actuator is provided at the upper end of the body side tube 2 to which the upper end of the piston rod 12 is connected, that is, the upper end of the front fork F.

[0059] In summary, the front fork F of the present embodiment can adjust the extension side damping force and the compression side damping force on the upper end side of the front fork F. In addition, in the front fork F of the present embodiment, if the actuator 6 is provided on the upper end side of the front fork F, the first damping force adjustment valve V1 and the second damping force adjustment valve V2 can be adjusted. Therefore, according to the front fork F of the present embodiment, there is no need to dispose the actuator at the lower end of the front fork F closest to the ground, and it is easier to protect the actuator and handle the wiring of the actuator.

[0060] In addition, in the front fork F of the present embodiment, it is configured to transmit the power of the actuator 6 to the first damping force regulating valve V1 and the second damping force regulating valve V2 through the control rod 32, thereby adjusting the damping forces of both extension and compression. However, it may also be configured to use a regulator instead of the actuator 6, install the regulator at the front end of the piston rod 12, and enable the control rod 32 to move axially (up and down direction) through the manual operation of the user. In addition, for the regulator, for example, as long as it has an operation portion rotatably mounted on the cover 4 or the piston rod 12 and a feed screw mechanism that moves up and down relative to the cover 4 or the piston rod 12 through the rotation of the operation portion, and as long as it can transmit the up and down movement of the feed screw mechanism to the first valve needle 30 and the second valve needle 33 through the control rod 32. In addition, it may also be a regulator in which the operation portion is screwed onto the cover 4 or the piston rod 12 to form a feed screw mechanism.

[0061] In addition, in the front fork F of the present embodiment, the second damping force regulating valve V2 is interlocked with the first damping force regulating valve V1 to adjust the resistance applied to the passing liquid flow. According to the front fork F configured in this way, only by using one actuator 6, the first damping force regulating valve V1 and the second damping force regulating valve V2 can respectively adjust the resistance applied to the liquid flow passing through them. Therefore, according to the front fork F of the present embodiment, only one actuator 6 for driving the first damping force regulating valve V1 needs to be installed on the upper end side of the fork body 1, and the electrification of the damping force adjustment for both extension and compression of the front fork F can be achieved at a lower cost.

[0062] Furthermore, the front fork F of the present embodiment includes an actuator 6 and a control rod 32 for transmitting the power of the actuator 6 to the first damping force regulating valve V1. The first damping force regulating valve V1 and the second damping force regulating valve V2 can move axially within the piston rod 12 and are arranged in series along the axial direction. According to the front fork F configured in this way, since the first damping force regulating valve V1 and the second damping force regulating valve V2 can move axially within the piston rod 12 and are arranged in series, a structure in which the first damping force regulating valve V1 directly presses the second damping force regulating valve V2 can be adopted. The power of the actuator 6 is transmitted to the first damping force regulating valve V1 and the second damping force regulating valve V2 through one control rod 32, and the second damping force regulating valve V2 can be interlocked with the first damping force regulating valve V1. Therefore, according to the front fork F of the present embodiment, the electrification of the damping force adjustment for both extension and compression of the front fork F can be achieved by adopting a simple structure, and the manufacturing cost of the front fork F can be further reduced.

[0063] In addition, in the front fork F of the present embodiment, both the first damping force adjusting valve V1 and the second damping force adjusting valve V2 are needle valves. Therefore, by setting the inclination angles of the conical surfaces on the outer circumferences of the head 30a of the first valve needle 30 and the head 33a of the second valve needle 33, it is possible to easily optimize the degree of change in the flow path area corresponding to the displacement amounts of the first valve needle 30 and the second valve needle 33, and it is possible to simply achieve the optimization of the adjustment of the extension-side damping force and the compression-side damping force, making the adjustment easier.

[0064] Furthermore, in the front fork F of the present embodiment, the second damping force adjusting valve V2 has a second annular valve seat 23e provided on the inner circumference of the piston rod 12, a second valve needle 33 movably inserted into the piston rod 12 in the axial direction, a second spring 34 accommodated in the piston rod 12 and biasing the second valve needle 33 in a direction away from the second annular valve seat 23e, and also includes a collar (second stopper) 24 provided on the inner circumference of the piston rod 12 that restricts the movement of the second valve needle 33 in a direction away from the second annular valve seat 23e when it abuts against the second valve needle 33. The second valve needle 33 has a guiding portion 33c that slidably contacts the inner circumference of the piston rod 12 and faces the collar (second stopper) 24 in the axial direction and serves as a spring seat for the second spring 34. According to the front fork F configured in this way, since the second valve needle 33 has the guiding portion 33c, it can be displaced relative to the second annular valve seat 23e provided in the piston rod 12 without axial jitter. Therefore, the extension-side damping force of the front fork F can be adjusted as needed. And when the second valve needle 33 abuts against the collar 24 serving as the second stopper, the flow path area of the second damping force adjusting valve V2 will not further increase. Therefore, it is possible to avoid the occurrence of insufficient damping force when reducing the extension-side damping force of the front fork F. In addition, the guiding portion 33c can also serve as a spring seat for the second spring 34. Therefore, according to the front fork F configured in this way, even if the guiding portion 33c of the second valve needle 33 concentrates the three functions of restricting the maximum flow path area of the second damping force adjusting valve V2, guiding the movement of the second valve needle 33, and serving as a spring seat for the second spring 34, it is possible to avoid the complication of the structure of the second valve needle 33, thereby reducing the manufacturing cost of the front fork F.

[0065] In addition, the first damping force regulating valve V1 and the second damping force regulating valve V2 can also be valves other than needle valves that can regulate the flow path area and perform pressure control. Therefore, in addition to needle valves, the first damping force regulating valve V1 and the second damping force regulating valve V2 can be, for example, valves such as spool valves or rotary valves or lift valves. The following describes modification examples of the first damping force regulating valve V1 and the second damping force regulating valve V2. When describing each modification example, for the components that are the same as those of the first damping force regulating valve and the second damping force regulating valve in each modification example, since the description will be repeated, the same reference signs are marked and the detailed description is omitted.

[0066] In addition, as Figure 3 shown, when it is not necessary to interlock the first damping force regulating valve V1a and the second damping force regulating valve V2a in the first modification example, it can also be designed to remove the transmission shaft 33d of the second valve needle 33, axially penetrate the center of the first valve needle 30 in the control rod 32, and axially movably insert the second control rod 35 that abuts against the rear end of the guide portion 33c of the second valve needle 33 from which the transmission shaft 33d has been removed. An unillustrated first regulator capable of axially moving the control rod 32 and an unillustrated second regulator capable of axially moving the second control rod 35 are provided, so that the first valve needle 30 of the first damping force regulating valve V1a and the second valve needle 33 of the second damping force regulating valve V2a are axially displaced independently of each other. In this case, since the resistance exerted on the liquid flowing through the first damping force regulating valve V1a and the second damping force regulating valve V2a can be independently adjusted, the user can independently adjust the characteristics of the extension side damping force and the compression side damping force of the front fork F. In addition, if it is Figure 3 the manner shown, although the first valve needle 30 is not subjected to the force from the second spring 34, due to the pressure from the extension side chamber R1, it will be pressed against the control rod 32. Therefore, a spring for applying an additional force to the first valve needle 30 may not be provided, but a spring may also be provided to apply a force so that the first valve needle 30 abuts against the control rod 32.

[0067] Furthermore, as Figure 4In the first damping force regulating valve V1b and the second damping force regulating valve V2b in the second modification example shown, the first damping force regulating valve V1b and the second damping force regulating valve V2b may also be rotary valves having a cylindrical valve body that rotates within the piston rod 12. The first damping force regulating valve V1b includes a cylindrical valve body 36 having a port 36a that can face a groove 22c provided on the inner periphery of the lower end of the piston rod main body 22. By rotating the cylindrical valve body 36, the area of the port 36a facing the groove 22c can be changed, thereby enabling adjustment of the flow path area. The second damping force regulating valve V2b includes a cylindrical valve body 37 having a port 37a that opens from the lower end to the side of the lower surface of the center rod 23 facing the compression side chamber R2 and can face a hole 23f leading into the center rod 23. By rotating the cylindrical valve body 37, the area of the port 37a facing the hole 23f can be changed, thereby enabling adjustment of the flow path area.

[0068] When it is desired to drive the cylindrical valve bodies 36 and 37 of the first damping force regulating valve V1b and the second damping force regulating valve V2b separately, as Figure 4 shown, by providing a cylindrical first control rod 38 connected to the cylindrical valve body 36 and inserted into the piston rod 12, and a second control rod 39 connected to the cylindrical valve body 27 and inserted into the first control rod 38, the user can rotate the first control rod 38 and the second control rod 39 from the outside, thereby enabling independent adjustment of the flow path areas of the first damping force regulating valve V1b and the second damping force regulating valve V2b. In this case, for example, the upper end of the first control rod 38 can protrude outward from the upper end of the cover 4, and the upper end of the second control rod 39 can protrude outward from the upper end of the first control rod 38, so that the user can rotate the first control rod 38 and the second control rod 39. Further, when it is desired to interlock the first damping force regulating valve V1b and the second damping force regulating valve V2b, the second control rod 39 is removed, the cylindrical valve body 36 and the cylindrical valve body 37 are connected, and by rotating the first control rod 38, the flow path areas of the first damping force regulating valve V1b and the second damping force regulating valve V2b can be adjusted simultaneously. At this time, an actuator for rotationally driving the first control rod 38 can also be provided on the cover 4 to make the adjustment of the flow path areas of the first damping force regulating valve V1b and the second damping force regulating valve V2b electric.

[0069] Furthermore, it can also be as Figure 5Similar to the first damping force adjusting valve V1c and the second damping force adjusting valve V2c of the third modified example shown, the second damping force adjusting valve V2c is generally connected to the first valve needle 30 in the first damping force adjusting valve V1c as a spool valve. The second damping force adjusting valve V2c is a spool valve that includes a valve core 40 that slidably contacts the inner periphery below the port 23d of the center rod 23, and a connecting rod 41 that connects the valve core 40 to the front end of the first valve needle 30. The opening and closing degree of the groove 23g provided on the inner periphery below the port 23d of the center rod 23 is adjusted by the displacement of the valve core 40. In addition, in order to position the first valve needle 30 and the valve core 40 at the initial position, a spring 46 is clamped between the guiding portion 30c of the first valve needle 30 and the collar 24. Thus, the first damping force adjusting valve V1c and the second damping force adjusting valve V2c are not the same valves, and they can also be different valves. If the first damping force adjusting valve V1 and the second damping force adjusting valve V2 are arranged in series axially movable within the piston rod 12, the first damping force adjusting valve V1c and the second damping force adjusting valve V2c can be interlocked with each other without a complicated structure. In addition, when the interlock between the first damping force adjusting valve V1c and the second damping force adjusting valve V2c is not required, the first valve needle 30 and the valve core 40 can also be displaced independently by adopting a structure having two control rods as shown in Figure 3 shown.

[0070] In addition, similar to Figure 6 shown in the fourth modified example where the first damping force adjusting valve V1d and the second damping force adjusting valve V2d are concerned, when the interlock between the first damping force adjusting valve V1d and the second damping force adjusting valve V2d is not required, the second damping force adjusting valve V2d can also be a lift valve. The lift valve is accommodated on the inner peripheral side below the port 23d of the center rod 23 and is composed of a lift type valve body 43 that can be separated and seated on a second annular valve seat 42 provided on the inner periphery below the port 23d of the center rod 23, and a second spring 44 that applies a force in the direction of seating the lift type valve body 43 on the second annular valve seat 42, that is, upward. And, as shown in Figure 6As shown, it is also possible to use a second control rod 45 inserted into the control rod 32 and axially passing through the center of the first valve needle 30 to abut against the lift-type valve body 43, and apply a force to the lift-type valve body 43 in a direction away from the second annular valve seat 42, so as to adjust the opening pressure of the second damping force regulating valve V2 and thus adjust the resistance applied to the passing liquid flow. In this case, it is only necessary to provide an actuator or a spring that presses the second control rod 45 to adjust the acting force. In addition, when only adjusting the opening degree of the lift-type valve body 43, it is also possible to provide a regulator or an actuator that moves the second control rod 45 in the up and down directions. Even if the first damping force regulating valve V1d and the second damping force regulating valve V2d are configured in this way, it is possible to adjust the resistance applied by the first damping force regulating valve V1d to the passing liquid flow from the upper end side of the front fork F and thus adjust the extension side damping force of the front fork F, and it is also possible to adjust the resistance applied by the second damping force regulating valve V2d to the passing liquid flow from the upper end side of the front fork F and thus adjust the compression side damping force of the front fork F.

[0071] Furthermore, in the front fork F of the present embodiment, the first damping force regulating valve V1 and the second damping force regulating valve V2 are provided below the liquid level O of the liquid storage chamber R. Therefore, the first damping force regulating valve V1 and the second damping force regulating valve V2 are always arranged in the liquid. Therefore, according to the front fork F of the present embodiment, it is possible to prevent a delay in the generation of the damping force of the first damping force regulating valve V1 and the second damping force regulating valve V2 during the telescopic movement.

[0072] Further, in the front fork F of the present embodiment, the shock absorber D includes: an extension-side damping valve 14 provided on the extension-side damping passage 11b that communicates the extension-side chamber R1 and the compression-side chamber R2, and applying resistance to the liquid flow from the extension-side chamber R1 to the compression-side chamber R2; a compression-side check valve 13 provided on the compression-side passage 11a that communicates the compression-side chamber R2 and the extension-side chamber R1, and only allowing the liquid to flow from the compression-side chamber R2 to the extension-side chamber R1; a compression-side damping valve 17 provided on the compression-side damping passage 16a that communicates the compression-side chamber R2 and the liquid storage chamber R, and applying resistance to the liquid flow from the compression-side chamber R2 to the liquid storage chamber R; an intake check valve 18 provided on the intake passage 16b that communicates the compression-side chamber R2 and the liquid storage chamber R, and only allowing the liquid to flow from the liquid storage chamber R to the compression-side chamber R2. In the front fork F configured as such, by having the circuit structure, it becomes a bi-directional flow type shock absorber in which the liquid in the extension-side chamber R1 moves to the compression-side chamber R2 when the shock absorber D extends, and the liquid in the compression-side chamber R2 moves to the extension-side chamber R1 when it contracts. However, even for the bi-directional flow type shock absorber D, the damping forces during both the extension and contraction actions can be adjusted by the first damping force adjusting valve V1 and the second damping force adjusting valve V2, and the characteristics of the damping forces during the extension and contraction actions can be independently set by the extension-side damping valve 14 and the compression-side damping valve 17, and the extension-side damping force and the compression-side damping force that are most suitable for suppressing vehicle vibrations can be generated.

[0073] The preferred embodiments of the present invention have been described in detail above, but modifications, deformations, and changes can be made as long as they are within the scope of the claims. Symbol Explanation

[0074] 1 Fork main body 2 Vehicle body side tube 3 Axle side tube 10 Cylinder 11 Piston 11a Compression side passage 11b Extension side damping passage 12 Piston rod 13 Compression side check valve 14 Extension side damping valve 6 Actuator 16a Compression side damping passage 16b Intake passage 17 Compression side damping valve 18 Intake check valve 23e Second annular valve seat 24 Collar (second stopper) 32 Control lever 33 Second valve needle 33c Guide part 34 Second spring D Shock absorber F Front fork P1 First damping force adjustment channel P2 Second damping force adjustment channel R Liquid storage chamber R1 Extension side chamber R2 Compression side chamber V1, V1a, V1b, V1c, V1d First damping force regulating valve V2, V2a, V2b, V2c, V2d Second damping force regulating valve

Claims

1. A front fork, The front fork comprises: a telescopic fork body having a body side tube and an axle side tube, and a shock absorber accommodated in the fork body and clamped between the body side tube and the axle side tube, The shock absorber has: a cylinder connected to the axle side tube; a piston axially movably inserted into the cylinder and partitioning the interior of the cylinder into an extension side chamber and a compression side chamber; a cylindrical piston rod axially movably inserted into the cylinder, with its upper end connected to the body side tube and its lower side connected to the piston; a first damping force adjustment passage provided in the piston rod and communicating the extension side chamber with a liquid storage chamber formed by the space between the fork body and the shock absorber; a second damping force adjustment passage provided in the piston rod and communicating the extension side chamber and the compression side chamber; a first damping force adjustment valve provided in the piston rod and capable of adjusting the resistance applied to the liquid flow passing through the first damping force adjustment passage; a second damping force adjustment valve provided in the piston rod and capable of adjusting the resistance applied to the liquid flow passing through the second damping force adjustment passage.

2. The front fork according to claim 1, The second damping force adjustment valve is interlocked with the first damping force adjustment valve to adjust the resistance.

3. The front fork according to claim 2, which comprises: an actuator; a control rod for transmitting the power of the actuator to the first damping force adjustment valve; The first damping force adjustment valve and the second damping force adjustment valve can axially move in the piston rod and are arranged in series along the axial direction.

4. The front fork according to claim 3, Both the first damping force adjustment valve and the second damping force adjustment valve are needle valves.

5. The front fork according to claim 4, The second damping force adjustment valve has: a second annular valve seat provided on the inner periphery of the piston rod; a second valve needle axially movably inserted into the piston rod; a second spring accommodated in the piston rod and biasing the second valve needle away from the second annular valve seat; It also has a second stopper provided on the inner periphery of the piston rod, which restricts the movement of the second valve needle away from the second annular valve seat when abutting against the second valve needle, The second valve needle has a guiding portion that slidably contacts the inner periphery of the piston rod, is axially opposed to the second stopper, and functions as a spring seat for the second spring.

6. The front fork according to claim 1, When the shock absorber performs an extension action and a contraction action, the liquid flows in the same direction in the first damping force adjustment passage, When the shock absorber performs an extension action and a contraction action, the liquid flows in different directions in the second damping force adjustment passage.

7. The front fork according to any one of claims 1 to 6, Characterized in that: The shock absorber has: An extension-side damping valve, which is arranged on an extension-side damping passage connecting the extension-side chamber and the compression-side chamber, and applies resistance to the liquid flow from the extension-side chamber to the compression-side chamber; A compression-side check valve, which is arranged on a compression-side passage connecting the compression-side chamber and the extension-side chamber, and only allows liquid to flow from the compression-side chamber to the extension-side chamber; A compression-side damping valve, which is arranged on a compression-side damping passage connecting the compression-side chamber and the liquid storage chamber, and applies resistance to the liquid flow from the compression-side chamber to the liquid storage chamber; An intake check valve, which is arranged on an intake passage connecting the compression-side chamber and the liquid storage chamber, and only allows liquid to flow from the liquid storage chamber to the compression-side chamber.

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