Front fork

Abstract

To provide a front fork which enables easy assembly and can easily deal with changes of inner and outer diameters of a fork body.SOLUTION: A front fork 1 includes: a fork body F; a rod 4 housed in the fork body; a cylindrical lock case 5c which may move in an axial direction relative to the rod 4; a lock piece 6 which defines a lock chamber B in the lock case 5c and allows the inside and the outside of the lock chamber B to communicate with each other; a spring member 7 which biases the lock piece 6; a spring receiver 8 having a fitting part 8a fitted in an inner periphery of the lock case 5c, and a seat part 8b facing an end of the lock case 5c; a suspension spring 9 supported by a part of the fork body F and the seat part 8b; and a stopper 10 which is attached to the rod 4 and closes the passage P when contacting with the lock piece 6. The fitting part 8a prevents the lock piece 6 from being removed from the lock case 5c.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Conventionally, a front fork is configured with, for example, a fork body having an outer tube and an inner tube inserted into the outer tube so as to be axially movable, and a damper cartridge housed within the fork body. The fork is interposed between the front wheel and the body of a saddle-type vehicle, and when the fork extends or retracts, the damper cartridge built into the fork body generates a damping force to reduce vibration of the body.

[0003] Such front forks are sometimes equipped with a hydraulic locking mechanism to absorb the impact at full compression. Specifically, the hydraulic locking mechanism includes a cylindrical lock case provided on a head member attached to one end of the cylinder of the damper cartridge, a lock piece housed within the lock case so as to be axially movable and having a passage connecting the inside and outside of the lock case, a spring member interposed between the lock case and the lock piece to bias the lock piece in a direction that pushes it out of the lock case, and a stopper attached to the rod of the damper cartridge and facing the lock piece in the axial direction.

[0004] In a front fork configured in this manner, when the damper cartridge contracts along with the fork body and the stopper attached to the rod moves toward the lock case and comes into contact with the lock piece, it blocks the passage of the lock piece and pushes the lock piece into the lock case, causing the pressure inside the lock case to rise and generating a force that prevents the fork body from contracting, stopping the front fork from contracting. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-78395 Summary of the Invention [Problem to be solved by the invention]

[0006] In such conventional front forks, a bottom cap that closes the end of the cylinder in the damper cartridge is fastened with a bolt to an axle bracket that closes the lower end of the inner tube and grips the axle of the front wheel of a saddle-ride type vehicle. Therefore, in conventional front forks, in order to tighten the bolts when attaching the damper cartridge to the inner tube, it is necessary to orient the end of the cylinder on the lock case side downward.

[0007] However, in conventional front forks, while the suspension spring prevents the lock piece and spring member from falling out of the lock case, the lock case, lock piece, and spring member that make up the hydraulic locking mechanism must be assembled to the cylinder before the damper cartridge is attached to the inner tube. Therefore, if the lock case side end of the cylinder is pointed downward when attaching the damper cartridge to the inner tube, the lock piece and spring member will fall out of the lock case.

[0008] Therefore, when attaching the damper cartridge to the inner tube, it is necessary to attach the damper cartridge to the inner tube while preventing the lock piece and spring member from falling out of the lock case, which makes the work very troublesome.

[0009] Furthermore, if the damper cartridge is shared and the diameter of the fork body is changed to increase the inner diameter of the fork body in accordance with use on a saddle-type vehicle, the suspension spring also needs to be made larger in diameter because its outer circumference is constrained by the inner tube.However, with conventional damper cartridges, the end of the lock case also serves as a spring support for the suspension spring, making it impossible to ensure a seating surface for the suspension spring, making it difficult to change the design of the inner and outer diameters of the fork body.

[0010] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a front fork that is easy to assemble and can easily accommodate changes in the inner and outer diameters of the fork body. [Means for solving the problem]

[0011] A front fork that solves the above problem includes a fork body having an outer tube and an inner tube inserted into the outer tube so as to be movable in the axial direction; a rod connected to one of the outer tube and the inner tube and housed within the fork body; a cylindrical lock case connected to the other of the outer tube and the inner tube and housed within the fork body, the cylindrical lock case being disposed on the outer periphery of the rod and movable in the axial direction relative to the rod; a lock piece that is annular and has the rod inserted through its inner periphery and slidably housed within the lock case, movable in the axial direction relative to the rod and the lock case, defining a lock chamber within the lock case and having a passage that communicates between the inside and outside of the lock chamber; the spring bearing having a fitting portion that fits around the inner periphery of the lock case and a seat portion that is connected to the end of the fitting portion opposite the lock case and faces the end of the lock case; a suspension spring that is arranged on the outer periphery of the rod and is a coil spring with one end supported by a part of the fork body and the other end supported by the seat portion; and a stopper that is attached to the rod and is movable in the axial direction within the suspension spring, and that moves in a direction approaching the lock case and abuts against the lock piece, blocking the passage and pushing the lock piece into the lock case; the abutment of the fitting portion of the spring bearing against the lock piece prevents the lock piece from coming out of the lock case.

[0012] With a front fork configured in this manner, the fitting portion of the spring receiver prevents the lock piece from coming loose, so the lock piece will not fall out of the lock case when assembling the front fork, making assembly easier. Also, even if the inner and outer diameters of the suspension spring are increased in conjunction with an increase in the diameter of the fork body, the spring receiver can be replaced to accommodate the increase in diameter of the fork body and suspension spring without changing the dimensions of the lock case, lock piece, and stopper that make up the hydraulic locking mechanism. This eliminates the need to prepare a large number of hydraulic locking mechanisms of different dimensions when manufacturing front forks of different diameters, making it easy to accommodate changes in the inner and outer diameters of the fork body.

[0013] The inner diameter of the suspension spring at the lock case side end may be larger than the outer diameter of the lock case. With a front fork configured in this manner, the seat surface of the seat portion that supports the suspension spring can be secured, so the suspension spring can be stably supported even if the diameter of the suspension spring is large for a lock case with a small diameter.

[0014] Furthermore, the lock case of the front fork has an orifice hole in the sliding range of the lock piece, and the lock piece has a tapered surface on the outer periphery of the lock case side end that becomes smaller in diameter as it moves toward the lock case. With a front fork configured in this way, the speed can be gradually reduced and the compression can be stopped before reaching the end of the compression stroke, effectively mitigating the impact at the time of maximum compression.

[0015] Alternatively, the spring member may be a coil spring, and the passage may be formed by a notch that opens from the inner periphery of the lock piece, extends radially, and has a tip that is located outer circumferentially of the lock piece relative to the position where the spring member abuts. With a front fork configured in this manner, the passage is not entirely blocked even when the spring member abuts the lock piece, and communication between the lock chamber and the liquid reservoir chamber can be ensured via the passage. In addition, when assembling the hydraulic locking mechanism to the cylinder of the shock absorber prior to attaching the shock absorber to the inner tube, the worker can visually check through the notch whether the spring member is assembled in the correct position and whether any spring member has been forgotten to be inserted, thereby improving work efficiency when assembling the front fork.

[0016] Furthermore, the outer diameter of the seat portion of the spring bearing in the front fork may be larger than the outer diameter of the lock case. With a front fork configured in this manner, the suspension spring can be stably supported even if the suspension spring has an outer diameter larger than the outer diameter of the lock case. [Effects of the Invention]

[0017] The front fork of the present invention is easy to assemble and can easily accommodate changes in the inner and outer diameters of the fork body. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a cross-sectional view of a front fork according to an embodiment of the present invention. [Figure 2] 1 is an enlarged partial cross-sectional view of a front fork according to an embodiment of the present invention. [Figure 3] FIG. 1 is a plan view showing an oil lock piece of a front fork according to one embodiment of the present invention. [Figure 4] FIG. 10 is an enlarged partial cross-sectional view of the front fork in a state where the stopper is in contact with the lock piece. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention will be described below based on the embodiment shown in the drawings. As shown in Fig. 1, a front fork 1 in one embodiment is configured to include a fork body F having an outer tube 2 and an inner tube 3 inserted into the outer tube 2 so as to be axially movable, a rod 4 connected to the outer tube 2 and housed in the fork body F, a lock case 5c connected to the inner tube 3 and housed in the fork body F, a lock piece 6 that defines a lock chamber B in the lock case 5c, a spring member 7 that biases the lock piece 6 in a direction that expands the lock chamber B, a spring bearing 8 fitted in the lock case 5c, a suspension spring 9 made of a coil spring interposed between the outer tube 2 and the spring bearing 8, and a stopper 10 attached to the rod 4. In the front fork 1 of this embodiment, the lock case 5c, the lock piece 6, the spring member 7, the spring bearing 8, and the stopper 10 configure a hydraulic locking mechanism L that prevents the front fork 1 from contracting when it is fully compressed.

[0020] The front fork 1 of this embodiment houses a shock absorber D, which has a cylinder 11 through which a rod 4 moves in and out and which generates a damping force when it extends or retracts, within the fork body F, and the outer tube 2 is connected to the body of a saddle-riding type vehicle (not shown) and the inner tube 3 is connected to an axle on which the front wheel of the saddle-riding type vehicle is mounted, so that the front fork 1 is interposed between the body and the front wheel of the saddle-riding type vehicle. The front fork 1 suppresses vibrations of the vehicle body with the damping force generated by the shock absorber D when it contracts due to vibrations input from the road surface while the saddle-riding type vehicle is traveling.

[0021] Below, each part of the front fork 1 will be described in detail. The fork body F includes an outer tube 2 and an inner tube 3 inserted into the outer tube 2 so as to be movable in the axial direction, and expands and contracts as the inner tube 3 moves in and out of the outer tube 2. In this embodiment, the fork body F is an inverted type, with the outer tube 2 facing upward (towards the vehicle body) and the inner tube 3 facing downward (towards the axle).

[0022] The outer tube 2 is connected to the vehicle body via a vehicle body side bracket (not shown), and the inner tube 3 is connected to the front wheel axle via an axle bracket 12. In this way, the front fork 1 is interposed between the vehicle body and the axle, and when the front wheel vibrates up and down, for example when the vehicle is traveling on an uneven road surface, the inner tube 3 moves in and out of the outer tube 2, causing the shock absorber D in the fork body F to expand and contract. Note that the fork body F may be of an upright type, with the outer tube 2 serving as the axle side tube and the inner tube 3 serving as the vehicle body side tube.

[0023] Next, the upper end of the outer tube 2 is closed with a cap 13. The lower end of the inner tube 3 is closed with an axle bracket 12. Furthermore, the area where the outer tube 2 and the inner tube 3 overlap in the radial direction is closed with a seal member 18.

[0024] In this way, the fork body F is sealed, the shock absorber D is housed inside, and a liquid reservoir chamber R is formed between the fork body F and the shock absorber D. The liquid reservoir chamber R stores a liquid such as hydraulic oil, and a gas is sealed above the liquid surface.

[0025] The shock absorber D comprises a cylinder 11 that contains a liquid such as hydraulic oil, an annular head member 5 attached to the upper end of the cylinder 11, and a rod 4 that is slidably supported on the head member 5 and inserted into the cylinder 11 so that it can move axially.The shock absorber D generates a damping force by providing resistance to the flow of hydraulic oil that occurs when the cylinder 11 and the rod 4 move relative to each other in the axial direction.

[0026] 1 , the shock absorber D includes a cylinder 11, a rod 4 inserted into the cylinder 11 so as to be axially movable, a piston 14 connected to the rod 4 and inserted into the cylinder 11 so as to be axially movable, and dividing the interior of the cylinder 11 into an extension-side chamber R1 and a compression-side chamber R2 filled with liquid, a bottom cap 15 closing the lower end of the cylinder 11, and a partition wall 16 attached to a shaft 15a extending from the bottom cap 15 and fitted into the cylinder 11 to divide an intermediate chamber A below the compression-side chamber R2 and in communication with the liquid reservoir chamber R via a hole 11a provided below the cylinder 11. Note that the fluid filled in the shock absorber D and the liquid reservoir chamber R is not limited to hydraulic oil, and may be a liquid other than hydraulic oil, such as water or an aqueous solution, or a gas.

[0027] 1 and 2, the rod 4 protrudes outside the cylinder 11 through the inner periphery of the annular head member 5 that is fitted onto the upper end of the cylinder 11. The upper end of the rod 4 is connected to the cap 13 that closes the upper end of the outer tube 2, as described above.

[0028] The piston 14 is provided with an extension-side damping passage 14a that communicates between the extension-side chamber R1 and the compression-side chamber R2, allows liquid to flow only from the extension-side chamber R1 to the compression-side chamber R2, and provides resistance to the liquid flow, and a compression-side passage 14b that communicates between the compression-side chamber R2 and the extension-side chamber R1, and allows liquid to flow only from the compression-side chamber R2 to the extension-side chamber R1.

[0029] The partition 16 also has a compression side damping passage 16a that connects the compression side chamber R2 and the intermediate chamber A, allowing only the flow of liquid from the compression side chamber R2 to the liquid reservoir chamber R and providing resistance to the flow of liquid, and a suction passage 16b that connects the intermediate chamber A and the compression side chamber R2, allowing only the flow of liquid from the liquid reservoir chamber R to the compression side chamber R2.

[0030] The bottom cap 15 of the shock absorber D is fixed to the lower end of the cylinder 11 and has a screw hole 15b that opens from the lower end. The axle bracket 12, which is attached to the outer periphery of the lower end of the inner tube 3 by screw connection, is cylindrical with a bottom and has a retaining ring 12a at its lower end that holds the axle, as well as a bolt insertion hole 12b that penetrates the bottom. The shock absorber D is fastened to the inner tube 3 by a bolt 17 that is inserted into the bolt insertion hole 12b of the axle bracket 12 and screwed into the screw hole 15b of the bottom cap 15. When the bottom cap 15 is fastened to the axle bracket 12 by the bolt 17, the cylinder 11 is connected to the inner tube 3.

[0031] The shock absorber D configured in this manner expands and contracts together with the fork body F. When the shock absorber D extends, liquid moves from the extension-side chamber R1, which is compressed as the piston 14 moves relative to the cylinder 11, to the compression-side chamber R2 via the extension-side damping passage 14a, and the extension-side damping passage 14a provides resistance to the flow of liquid, causing the pressure in the extension-side chamber R1 to rise, causing the shock absorber D to generate a damping force that impedes the extension operation. Furthermore, when the shock absorber D extends, the rod 4 retracts from the cylinder 11, and liquid is supplied from the liquid reservoir chamber R into the cylinder 11 via the suction passage 16b.

[0032] On the other hand, when the shock absorber D contracts, the liquid moves from the compression-side chamber R2, which is compressed by the movement of the piston 14 relative to the cylinder 11, to the expansion-side chamber R1 via the compression-side passage 14b, and the rod 4 enters the cylinder 11, causing the liquid to move from the compression-side chamber R2 to the liquid reservoir chamber R via the compression-side damping passage 16a. Then, since the compression-side damping passage 16a provides resistance to the flow of liquid from the compression-side chamber R2 to the liquid reservoir chamber R, the pressure in the cylinder 11 rises, and the shock absorber D generates a damping force that obstructs the contraction operation.

[0033] Next, we will explain the hydraulic lock mechanism L. As described above, in the front fork 1 of this embodiment, the hydraulic lock mechanism L is made up of the lock case 5c, the lock piece 6, the spring member 7, the spring bearing 8, and the stopper 10.

[0034] The head member 5 is annular and includes an annular rod guide 5a whose outer periphery is screwed to the inner periphery of the cylinder 11 to fix it to the cylinder 11 and which supports the rod 4 inserted through the inner periphery, a flange 5b connected to the upper end of the rod guide 5a and abutting the upper end of the cylinder 11, and a cylindrical lock case 5c extending upward from the upper end of the flange 5b toward the opposite side to the cylinder. In this way, the head member 5 is attached to the cylinder 11, connected to the inner tube 3 via the cylinder 11, and housed in the fork body F.

[0035] As shown in Fig. 2, the rod guide 5a has a cylindrical bushing 5a1 on its inner periphery that guides the axial movement of the rod 4, and a threaded portion 5a2 on its outer periphery that is threadedly coupled to the inner periphery of the upper end of the cylinder 11. Furthermore, the rod guide 5a has a recess 5a3 on its inner periphery at the lock case side end, which is the upper end in Fig. 2. The recess 5a3 has a flat bottom surface 5a31 and a tapered side surface 5a32 that continues to the bottom surface 5a31, forming a mortar-shaped recess.

[0036] When the rod guide 5a is screwed to the upper end of the cylinder 11, the flange 5b abuts against the upper end of the cylinder 11 to restrict the head member 5 from entering the cylinder 11 and position the head member 5 axially relative to the cylinder 11.

[0037] The lock case 5c is cylindrical and has an orifice hole 5c1 provided on the side to communicate the inside and outside, and a plurality of notched grooves 5c2 provided on the upper end. The lock case 5c is located below the liquid level in the liquid reservoir chamber R and is constantly immersed in the liquid. The inner diameter of the lock case 5c is sufficiently larger than the outer diameter of the rod 4, and the rod 4 is inserted into the lock case 5c. The lock case 5c is arranged on the outer periphery of the rod 4 and can move axially together with the cylinder 11 relative to the rod 4.

[0038] A lock piece 6 is slidably inserted into the lock case 5c. The lock piece 6 is annular, and the rod 4 is inserted into the inner periphery of the lock piece 6, so that the lock piece 6 is slidably housed in the lock case 5c.

[0039] Specifically, as shown in Figures 2 and 3, the lock piece 6 has an annular bottom portion 6a, a cylindrical portion 6b extending from the outer periphery of the bottom portion 6a toward the cylinder, which is downward in Figure 2, a plurality of notches 6c opening from the inner periphery of the bottom portion 6a in Figure 3 and extending radially, and a tapered surface 6d provided on the outer periphery of the lower end of the cylindrical portion 6b in Figure 2.

[0040] When the lock piece 6 is housed in the lock case 5c with the cylindrical portion 6b facing the cylinder side, it defines a lock chamber B on the cylinder 11 side within the lock case 5c, and communicates the lock chamber B with the liquid reservoir chamber R outside the lock case 5c through a passage P formed by notches 6c on the inner periphery of the bottom portion 6a. Four notches 6c are provided on the bottom portion 6a and are formed in a fan shape.

[0041] In addition, the inner diameter of the bottom 6a of the lock piece 6 is larger than the outer diameter of the rod 4, so that the lock piece 6 can move axially relative to the rod 4 and can also move axially within the lock case 5c, guided by the inner periphery of the lock case 5c, without axial wobble.

[0042] The tapered surface 6d of the lock piece 6 is formed on the outer periphery of the lower end in Figure 2, which is the lock case side end of the cylindrical portion 6b, and is a surface that slopes so that the outer diameter becomes smaller as it approaches the lower end, which is the lock case side.

[0043] A spring bearing 8 is attached to the upper end of the lock case 5c in FIG. 2. The spring bearing 8 includes an annular fitting portion 8a that fits onto the inner periphery of the lock case 5c, a flange-shaped seat portion 8b that extends radially outward from the upper end of the fitting portion 8a, and a notched groove 8c that extends from the fitting portion 8a to the inner periphery of the seat portion 8b. The spring bearing 8 is fixed to the upper end of the lock case 5c by press-fitting the fitting portion 8a into the inner periphery of the upper end of the lock case 5c in FIG. 2. The inner diameter of the fitting portion 8a of the spring bearing 8 is smaller than the outer diameter of the lock piece 6. Therefore, when the spring bearing 8 is attached to the end of the lock case 5c after the lock piece 6 is inserted into the lock case 5c, even if the lock piece 6 attempts to come out of the lock case 5, the fitting portion 8a abuts against the lock piece 6, restricting the movement of the lock piece 6 in the direction of coming out of the lock case 5. In this way, in the front fork 1, the fitting portion 8a of the spring bearing 8 abuts against the lock piece 6, thereby preventing the lock piece 6 from coming out of the lock case 5c. The outer diameter of the seat portion 8b is larger than the outer diameter of the lock case 5c.

[0044] The notched grooves 5c2 of the lock case 5c and the notched grooves 8c of the spring bearing 8 are positioned to coincide in the circumferential direction, and the spring bearing 8 is attached to the upper end of the lock case 5c so that the notched grooves 5c2 and 8c are directly opposite each other. Therefore, when fastening the bottom cap 15 and the axle bracket 12 with the bolts 17, a jig can be inserted into the notched grooves 5c2 and 8c to disable the rotation of the cylinder 11, allowing the rotation of the bolts 17, which makes the fastening work of the bolts 17 easier and also makes it easier to manage the tightening torque of the bolts 17.

[0045] A spring member 7, which is a coil spring, is housed within the lock case 5c. The spring member 7 is interposed in a compressed state between the rod guide 5a and the inner periphery of the bottom portion 6a of the lock piece 6, and constantly biases the lock piece 6 upward relative to the lock case 5c, in a direction that expands the lock chamber B. Therefore, the lock piece 6 is biased by the spring member 7, and when no external force is applied, the lock piece 6 is positioned in a position (initial position) where it abuts against the lower end of the fitting portion 8a of the spring bearing 8 relative to the lock case 5c. When the lock piece 6 is positioned in a position where it abuts against the fitting portion 8a, the upper end of the tapered surface 6d of the cylindrical portion 6b of the lock piece 6 in FIG. 2 is positioned above the orifice hole 5c1 in the lock case 5c and does not block the orifice hole 5c1. 2 relative to the lock case 5c from a state in which the lock piece 6 is positioned to abut against the fitting portion 8a, the entire tapered surface 6d faces the orifice hole 5c1, and as the downward movement of the lock piece 6 progresses, the degree of communication between the orifice hole 5c1 and the lock chamber B gradually decreases. When the downward movement of the lock piece 6 continues and the outer peripheral surface of the cylindrical portion 6b above the tapered surface 6d faces the orifice hole 5c1, the degree of opening of the orifice hole 5c1 decreases, and as the lock piece 6 continues to move downward, the orifice hole 5c1 is gradually closed by the outer peripheral surface of the cylindrical portion 6b above the tapered surface 6d of the lock piece 6, and when the outer peripheral surface of the cylindrical portion 6b above the tapered surface 6d completely faces the orifice hole 5c1, the orifice hole 5c1 is closed. In this way, the orifice hole 5c1 is provided within the sliding range of the lock piece 6 in the lock case 5c, and is closed by the outer peripheral surface of the lock piece 6 when the lock piece 6 moves from the initial position in the direction of entering the lock case 5c.

[0046] Next, the spring member 7 has an inner diameter slightly larger than the outer diameter of the rod 4, and is prevented from shifting radially by the rod 4. The outer diameter of the spring member 7 is smaller than the outer diameter of the flat bottom surface 5a31 of the recess 5a3 of the rod guide 5a, and the lower end of the spring member 7 in FIG. 2 is housed in the recess 5a3 and abuts against the flat bottom surface 5a31 of the recess 5a3 of the rod guide 5a in the head member 5.

[0047] Therefore, when the spring member 7 is housed together with the lock piece 6 in the lock case 5c, the lower end of the spring member 7 is aligned along the tapered side surface 5a32 of the recess 5a3 and positioned at a position where it abuts against the bottom surface 5a31. Therefore, when the lock piece 6 is inserted into the lock case 5c and then the spring bearing 8 is attached to the lock case 5c, the spring member 7, which is inaccessible from outside the lock case 5c, can be positioned at an appropriate position where it abuts against the bottom surface 5a31 of the recess 5a3. When the lock piece 6, spring bearing 8, and spring member 7 are assembled with the head member 5 in this way, the spring member 7 is positioned at an appropriate position radially relative to the head member 5. Therefore, when the rod 4 is inserted into the assembled rod guide 5a, the rod 4 can be smoothly inserted into the spring member 7, which has a small clearance between it and the rod 4, and a situation where the spring member 7 interferes and prevents the rod 4 from being unable to be inserted can be prevented.

[0048] The outer diameter of the spring member 7 is larger than the inner diameter of the bottom 6a of the lock piece 6 and is set to a diameter that does not completely block each of the notches 6c provided in the bottom 6a. Therefore, even if the upper end of the spring member 7 in FIG. 2 abuts against the inner periphery of the lower end of the bottom 6a of the lock piece 6 in FIG. 2, the passage P formed by the notches 6c is not completely blocked, and communication between the lock chamber B and the liquid reservoir chamber R is ensured via the passage P. In other words, the notches 6c provided in the bottom 6a of the lock piece 6 open from the inner periphery of the bottom 6a, extend radially, and are positioned radially outward from the position where the spring member 7, which is the coil spring of the lock piece 6, abuts. Therefore, the notches 6c are not blocked even when the spring member 7 abuts against the lock piece 6. Although not shown, the spring member 7 may have flat portions formed by cutting the ends of the end winding portions at both ends to make them flat and improve seating. Therefore, by making the circumferential length of the flat portion at the end of the spring member 7 longer than the circumferential length of the notch 6c, it is possible to prevent the end of the spring member 7 from protruding outside the lock chamber B through the notch 6c, and a stable biasing force can be applied to the lock piece 6. Although the spring member 7 is a coil spring, it may be a spring or elastic body other than a coil spring as long as it can urge the lock piece 6 in a direction to retract from the lock case 5c and does not block the passage P.

[0049] The stopper 10 attached to the rod 4 is fixed to the outer periphery of the rod 4. When the fork body F is fully extended, the stopper 10 is positioned above the lock piece 6 and axially faces the lock piece 6. The outer diameter of the stopper 10 is smaller than the inner diameter of the fitting portion 8a of the spring bearing 8, allowing it to enter the fitting portion 8a and the lock case 5c. When the fork body F retracts near the retraction stroke end, the rod 4 penetrates deep into the cylinder 11, causing the stopper 10's lower end surface to abut against the upper end surface of the lock piece 6. The outer diameter of the stopper 10 is larger than the diameter of an imaginary circle passing through the tip of the notch 6c of the lock piece 6. Therefore, when the stopper 10's lower end surface abuts against the upper end surface of the lock piece 6, it completely blocks the inner periphery of the bottom portion 6a of the lock piece 6 and the notch 6c, cutting off communication between the lock chamber B and the liquid reservoir chamber R through the passage P.

[0050] The shape and structure of the stopper 10 can be modified as long as it can enter the spring bearing 8 and the lock case 5c and close the passage P when it abuts against the bottom 6a of the lock piece 6. Furthermore, when forming the passage P in the lock piece 6, it may be formed by a hole penetrating the bottom 6a instead of the notch 6c, as long as it can be closed when the stopper 10 abuts against it.

[0051] In this embodiment, the stopper 10 is formed in an annular shape and is fixed by crimping to a C-ring 20 attached to the outer periphery of the rod 4. However, the method of attaching the stopper 10 is not limited to the above and can be changed as appropriate. For example, the stopper 10 and the rod 4 may be formed integrally. Furthermore, the stopper 10 may be configured with one or more protrusions that protrude radially outward from the outer periphery of the rod 4.

[0052] The suspension spring 9 is a coil spring, and in FIG. 1 its upper end is supported by the cap 13, and its lower end is supported by the seat portion 8b of the spring bearing 8 attached to the head member 5. As described above, the cap 13 is connected to the outer tube 2, and the head member 5 is connected to the inner tube 3 via the cylinder 11. Therefore, the suspension spring 9 is interposed between the outer tube 2 and the inner tube 3, and constantly biases the fork body F in a direction that extends it. Therefore, when the front fork 1 is interposed between the vehicle body and the front wheel of a saddle-ride type vehicle, the suspension spring 9 exerts a resilient force to elastically support the vehicle body.

[0053] The inner diameter of the suspension spring 9 is larger than the outer diameter of the stopper 10, and the inner diameter of the lower end of the suspension spring 9 in FIG. 2, which is the lock case side end, is larger than the outer diameter of the lock case 5c. The outer diameter of the suspension spring 9 is slightly smaller than the inner diameter of the inner tube 3, and the outer periphery of the suspension spring 9 is centered by the inner periphery of the inner tube 3, preventing radial eccentricity of the suspension spring 9. The outer diameter of the seat portion 8b of the spring bearing 8 is larger than the outer diameter of the lock case 5c, and the lock case side end of the suspension spring 9 can be stably supported by the seat portion 8b.

[0054] As described above, the lower end of the suspension spring 9 is not supported directly by the suspension-spring-side end of the lock case 5c, but is supported by the flange-shaped seat portion 8b of the spring bearing 8 attached to the lock case 5c, so even if the inner and outer diameters of the suspension spring 9 are increased, it will be stably supported without modifying the lock case 5c. Note that the inner diameter of the lower end of the suspension spring 9 in FIG. 2, which is the lock-case-side end, may be smaller than the outer diameter of the lock case 5c. Furthermore, since it is sufficient for the suspension spring 9 to constantly bias the fork body F in the extension direction, it is sufficient for one end to be supported by a part of the fork body F and the other end to be supported by the seat portion 8b.

[0055] Furthermore, since the inner diameter of the suspension spring 9 is larger than the outer diameter of the stopper 10 and does not interfere with the stopper 10 in any way, the suspension spring 9 allows the stopper 10 to move relative to the suspension spring 9 together with the rod 4 in the axial direction, which is the up and down direction in Figure 2.

[0056] The front fork 1 is configured as described above, and the operation of the front fork 1 will be described below. When the front fork 1 extends or retracts, the rod 4 moves up and down (axially) together with the stopper 10 relative to the lock case 5c. When the front fork 1 extends or retracts, the shock absorber D, which extends or retracts together with the fork body F, exerts a damping force to suppress vibration of the vehicle body.

[0057] Furthermore, when the front fork 1 extends or retracts, if the front fork 1 does not move near the stroke end on the retraction side and the stopper 10 moves to a position away from the lock piece 6, the lock piece 6 remains in its initial position in contact with the fitting portion 8a of the spring bearing 8 inside the lock case 5c and does not move, allowing the rod 4 to move freely in the vertical direction in Figure 2 relative to the lock case 5c and the lock piece 6. Therefore, in this case, the hydraulic lock mechanism L does not operate, the movement of the rod 4 is not restricted, and the front fork 1 generates a damping force that prevents extension or contraction only by the shock absorber D.

[0058] On the other hand, when the front fork 1 is retracted, it is displaced close to the stroke end on the retraction side, and as shown in Figure 4, when the stopper 10 comes into contact with the lock piece 6, the passage P provided in the bottom portion 6a of the lock piece 6 is blocked by the stopper 10. If the front fork 1 continues to retract from this state, the stopper 10, which moves downward relative to the lock case 5c together with the rod 4, will try to move the lock piece 6 into the lock case 5c.

[0059] As a result, the spring member 7 is compressed, increasing the biasing force in the direction returning the lock piece 6 to its initial position, and the passage P is blocked and the lock piece 6 moves into the lock case 5c, compressing the lock chamber B and causing the liquid in the lock chamber B to pass through the orifice hole 5c1 and move into the liquid reservoir chamber R. The orifice hole 5c1 provides resistance to this liquid flow, increasing the pressure in the lock chamber B and generating a resistance force that prevents the lock piece 6 from moving into the lock case 5c. As a result, the front fork 1 is displaced to the vicinity of the stroke end on the compression side, and as it further compresses toward the stroke end, the hydraulic lock mechanism L generates a resistance force in addition to the damping force generated by the shock absorber D, preventing its own compression operation.

[0060] Furthermore, as the front fork 1 continues to retract, the lock piece 6 gradually closes the orifice hole 5c1, making it more difficult for the liquid in the lock chamber B to move to the liquid reservoir chamber R, increasing the resistance that prevents the front fork 1 from retracting. When the lock piece 6 completely closes the orifice hole 5c1, the lock chamber B is closed off. When the lock piece 6 then tries to move into the lock case 5c, the pressure in the lock chamber B rises even further, causing the front fork 1 to stop retracting toward the stroke end.

[0061] In this way, when the front fork 1 retracts near the stroke end and attempts to retract further, the hydraulic locking mechanism L gradually increases the resistance force to reduce the stroke speed, and eventually the locking chamber B is completely closed, stopping the retraction of the front fork 1, thereby mitigating the impact when the front fork 1 is fully retracted.

[0062] Next, when the fully contracted front fork 1 begins to extend and the stopper 10 moves upward together with the rod 4 relative to the lock case 5c and separates from the lock piece 6, the passage P is opened, the lock chamber B and the liquid reservoir chamber R are connected, and liquid is supplied into the lock chamber B. As a result, the lock piece 6 can move freely relative to the lock case 5c and returns to its initial position in accordance with the biasing force of the spring member 7.

[0063] As described above, the front fork 1 of this embodiment comprises: a fork body F having an outer tube 2 and an inner tube 3 inserted into the outer tube 2 so as to be movable in the axial direction; a rod 4 connected to one of the outer tube 2 and the inner tube 3 and housed within the fork body F; a cylindrical lock case 5c connected to the other of the outer tube 2 and the inner tube 3 and housed within the fork body F, the cylindrical lock case 5c being disposed on the outer periphery of the rod 4 and movable in the axial direction relative to the rod 4; a lock piece 6 having an annular shape, the rod 4 inserted into the inner periphery of which is slidably housed within the lock case 5c, the lock piece 6 being movable in the axial direction relative to the rod 4 and the lock case 5c, the lock chamber B being defined within the lock case 5c and having a passage P communicating between the inside and outside of the lock chamber B; a spring member 7 interposed between the lock piece 6 and the lock case 5c and biasing the lock piece 6 in a direction that expands the lock chamber B; a spring bearing 8 having a fitting portion 8a that fits around the inner periphery of the lock case 5c and a seat portion 8b that is connected to the end of the fitting portion 8a on the side opposite to the lock case and faces the end of the lock case 5c; a suspension spring 9 made of a coil spring that is disposed on the outer periphery of the rod 4 and interposed between one of the outer tube 2 and the inner tube 3 and the seat portion 8b; and a stopper 10 that is attached to the rod 4 and is movable in the axial direction within the suspension spring 9, and that moves in a direction approaching the lock case 5c and abuts against the lock piece 6, thereby blocking the passage P and pushing the lock piece 6 into the lock case 5c. The abutment of the fitting portion 8a of the spring bearing 8 against the lock piece 6 prevents the lock piece 6 from coming out of the lock case 5c.

[0064] Even if the outer diameter of the lock piece 6 is increased, the front fork 1 can avoid interference with the suspension spring 9, and the pressure-receiving area of the lock piece 6 is increased, generating a large resistance force when the front fork 1 is fully retracted, preventing bottoming out of the front fork 1. With the front fork 1 configured in this manner, the fitting portion 8a of the spring bearing 8 prevents the lock piece 6 from falling out, so even if the opening of the lock case 5c is faced downward during assembly of the front fork 1, the lock piece 6 will not fall out of the lock case 5c, making assembly easier. Furthermore, even if the inner and outer diameters of the suspension spring 9 are increased in accordance with an increase in the diameter of the fork body F, the larger diameters of the fork body F and the suspension spring 9 can be accommodated by simply replacing the spring bearing 8 without changing the dimensions of the lock case 5c, lock piece 6, and stopper 10 that constitute the hydraulic locking mechanism L. Therefore, it is not necessary to prepare a large number of hydraulic locking mechanisms L of different dimensions when manufacturing front forks 1 of different diameters, and changes in the inner and outer diameters of the fork body can be easily accommodated. As described above, the front fork 1 of this embodiment is easy to assemble and can easily accommodate changes in the inner and outer diameters of the fork body F.

[0065] The lock piece 6 is prevented from coming off by a spring bearing 8 fixed to the lock case 5c and will not fall out from within the lock case 5c, so there is no need for sliding contact with the outer periphery of the rod 4 and it can move smoothly in the axial direction within the lock case 5c without interference from the rod 4. Also, because the spring member 7 is aligned by the rod 4, the spring member 7 does not apply a biased biasing force to the lock piece 6 in the radial direction, which also allows the lock piece 6 to move smoothly in the axial direction and eliminates the need to provide an alignment part on the lock piece 6 to align the spring member 7. The number and shape of the notches 6c that form the passage P can be changed as desired depending on the flow path area of the passage P.

[0066] Furthermore, the inner diameter of the lock case side end of the suspension spring 9 is larger than the outer diameter of the lock case 5c. With the front fork 1 configured in this manner, even if the inner diameter of the lock case side end of the suspension spring 9 is larger than the outer diameter of the lock case 5c, a seat surface can be secured by the seat portion 8b that supports the suspension spring 9, so the suspension spring 9 can be stably supported even if the diameter of the suspension spring 9 is increased relative to the small diameter of the lock case 5c.

[0067] Furthermore, in the front fork 1 of this embodiment, the lock case 5c has an orifice hole 5c1 in the sliding range of the lock piece 6, and the lock piece 6 has a tapered surface 6d on the outer periphery of the lock case side end that becomes smaller in diameter toward the lock case side. With the front fork 1 configured in this manner, when the stopper 10 abuts against the lock piece 6 and pushes the lock piece 6 into the lock case 5c during the retraction operation, the degree of communication between the lock chamber B and the liquid reservoir chamber R gradually decreases, and the pressure in the lock chamber B gradually increases. This gradually increases the resistance force that prevents the front fork 1 from retracting, gradually reducing the speed at which the front fork 1 moves toward the retraction side. Therefore, with the front fork 1 of this embodiment, the speed can be gradually reduced and the retraction can be stopped before reaching the end of the stroke toward the retraction side, effectively mitigating the impact at the time of maximum retraction.

[0068] Furthermore, in the front fork 1 of this embodiment, the spring member 7 is a coil spring, and the passage P is formed by a notch 6c that opens from the inner periphery of the lock piece 6, extends radially, and has a tip that is located outer circumferentially of the lock piece 6 relative to the position at which the spring member 7 abuts. With the front fork 1 configured in this manner, the passage P is not entirely blocked even when the upper end of the spring member 7 in FIG. 2 abuts against the lock piece 6, and communication between the lock chamber B and the liquid reservoir chamber R can be ensured via the passage P. In addition, when assembling the hydraulic lock mechanism L to the cylinder 11 of the shock absorber D in advance of attaching the shock absorber D to the inner tube 3, the worker can visually check via the notch 6c whether the spring member 7 is assembled in the correct position and whether any spring member 7 has been forgotten to be inserted, thereby improving work efficiency when assembling the front fork 1.

[0069] Furthermore, in the front fork 1 of this embodiment, the outer diameter of the seat portion 8b of the spring bearing 8 is larger than the outer diameter of the lock case 5c. With the front fork 1 configured in this manner, even if a suspension spring 9 having an outer diameter larger than the outer diameter of the lock case 5 is used, the suspension spring 9 can be stably supported.

[0070] Although the preferred embodiment of the present invention has been described in detail above, modifications, variations and changes can be made without departing from the scope of the appended claims. [Explanation of symbols]

[0071] 1 Front fork, 2 Outer tube, 3 Inner tube, 4 Rod, 5c Lock case, 5c1 Orifice hole, 6 Lock piece, 6c Notch, 6d Tapered surface, 7 Spring member, 8 Spring holder, 8a Fitting portion, 9 Spring member, 10 Stopper, B Lock chamber, F Fork body, P Passage

Claims

1. a fork body having an outer tube and an inner tube inserted into the outer tube so as to be movable in the axial direction; a rod connected to one of the outer tube and the inner tube and housed within the fork body; a cylindrical lock case connected to the other of the outer tube and the inner tube and housed within the fork body, the lock case being disposed on an outer periphery of the rod and being movable in the axial direction relative to the rod; a lock piece that is annular, has the rod inserted through its inner periphery, is slidably housed within the lock case, is movable in the axial direction relative to the rod and the lock case, defines a lock chamber within the lock case, and has a passage that communicates between the inside and outside of the lock chamber; a spring member interposed between the lock case and the lock piece to bias the lock piece in a direction that expands the lock chamber; a spring bearing having a fitting portion that fits onto the inner periphery of the lock case and a seat portion that is connected to an end of the fitting portion opposite the lock case and faces an end of the lock case; a suspension spring that is a coil spring that is disposed on the outer periphery of the rod, one end of which is supported by a part of the fork body and the other end of which is supported by the seat portion; a stopper attached to the rod and movable in the axial direction within the suspension spring, which moves in a direction approaching the lock case and abuts against the lock piece to close the passage and push the lock piece into the lock case; The lock piece is prevented from coming out of the lock case by the fitting portion of the spring bearing coming into contact with the lock piece. A front fork characterized by:

2. The inner diameter of the lock case side end of the suspension spring is larger than the outer diameter of the lock case.

2. The front fork according to claim 1.

3. The lock case has an orifice hole in a sliding range of the lock piece, The lock piece has a tapered surface on the outer periphery of the lock case side end that becomes smaller in diameter toward the lock case side.

2. The front fork according to claim 1.

4. The spring member is a coil spring, The passage is formed by a notch that opens from the inner periphery of the lock piece, extends in the radial direction, and has a tip that is located on the outer periphery side of the position of the lock piece where the spring member abuts.

2. The front fork according to claim 1.

5. The outer diameter of the seat portion of the spring bearing is larger than the outer diameter of the lock case.

3. The front fork according to claim 2.

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