Front fork

Abstract

This front fork (1) comprises: a fork body (F); a rod (4) that is accommodated in the fork body; a head member (5) that has a rod guide (5a) which guides the movement of the rod (4) and a lock case (5b) which is cylindrical; a lock piece (6) that is accommodated in the lock case (5b) and that has a passage (P) which communicates the inside and outside of a lock chamber (B); a coil spring (7) that biases the lock piece (6); a suspension spring (9) that is supported by the lock case (5b) and part of the fork body (F); a stopper (10) that is installed on the rod (4) and that closes the passage (P) when in contact with the lock piece (6); and a retaining member (8) that prevents the lock piece (6) from slipping out of the lock case (5b), wherein at least one of the rod guide (5a) and the lock piece (6) has a recess (5a3) equipped with a bottom surface (5a31) and an inclined surface (5a32), and the coil spring (7) is supported by the bottom surface (5a31).

Description

Front fork

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

[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 may be equipped with a hydraulic locking mechanism to absorb the impact at full compression, as disclosed in JP 2019-78395 A. 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 coil spring interposed between the lock case and the lock piece and biasing 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 together with the fork body and the stopper attached to the rod moves toward the lock case and abuts against 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 resistance force that prevents the fork body from contracting, stopping the front fork from contracting. Also, because the stopper abuts against the lock piece to block the passage, the inner diameter of the lock case that supports the suspension spring can be made larger than the inner diameter of the suspension spring, increasing the pressure-receiving area of ​​the lock piece and making it possible to increase the resistance force regardless of the outer diameter of the front fork.

[0005] JP2019-78395A

[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 coil spring from coming off the lock case, the lock case, lock piece, and coil spring 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 coil spring will fall off downward from 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 coil spring from falling out of the lock case, which makes the work very troublesome.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a front fork that is easy to assemble while increasing the resistance force provided by a hydraulic locking mechanism.

[0010] A front fork that solves the above problem comprises 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; an annular rod guide connected to the other of the outer tube and the inner tube and housed within the fork body, the rod guide being movable in the axial direction relative to the rod and making sliding contact with the outer periphery of the rod to guide the movement of the rod; a head member having a cylindrical lock case that rises from the rod guide and is disposed on the outer periphery of the rod; and a lock chamber that is annular and has an inner diameter larger than the outer diameter of the rod, the rod being inserted into the inner periphery and having the outer periphery in sliding contact with the inner periphery of the lock case so as to be movable in the axial direction relative to the lock case, the lock chamber defining a lock chamber and a ring-shaped rod guide that is housed within the fork body and is movable in the axial direction relative to the rod and has an inner diameter larger than the outer diameter of the rod and has an outer diameter that is slidably contacted with the inner periphery of the lock case. a lock piece having a passage that communicates the two; a coil spring interposed between the lock case and the lock piece and biasing the lock piece in a direction that expands the lock chamber; a suspension spring disposed on the outer periphery of the rod and having one end supported by a part of the fork body and the other end supported by an end of the lock case; a stopper attached to the rod and movable axially within the suspension spring, which closes the passage and pushes the lock piece into the lock case when it moves in a direction approaching the lock case and abuts against the lock piece; and a stopper member attached to the inner periphery of the lock case and prevents the lock piece from slipping out of the lock case, wherein at least one of the rod guide and the lock piece has a recess that has a flat annular bottom surface formed along the circumferential direction on the inner periphery of the lock case and has an inclined surface that continues to the outer periphery of the bottom surface, and the coil spring is supported by the bottom surface.

[0011] Even if the outer diameter of the lock piece is increased, the front fork can avoid interference with the suspension spring, and the pressure-receiving area of ​​the lock piece can be increased to generate a large resistance force when the front fork is fully retracted, preventing the front fork from bottoming out. Furthermore, with this front fork, the coil spring is aligned by the inclined surface of the recess in the rod guide or lock piece, so the coil spring is positioned in a predetermined position inside the lock case that cannot be seen from the outside after the hydraulic locking mechanism is assembled. This makes it easy to insert the rod into the coil spring even if the clearance between the inner periphery of the coil spring and the outer periphery of the rod is small, and the stopper ring prevents the lock piece from falling out, so the lock piece will not fall out of the lock case even if the opening of the lock case is turned downward during assembly of the front fork.

[0012] 1 is a cross-sectional view of a front fork according to an embodiment of the present invention; FIG. 2 is a partially enlarged cross-sectional view of a front fork according to an embodiment of the present invention; FIG. 3 is a plan view showing an oil lock piece of a front fork according to an embodiment of the present invention; FIG. 4 is a partially enlarged cross-sectional view of a front fork in a state where a stopper abuts on the lock piece;

[0013] The present invention will be described below with reference to the embodiment shown in the drawings. As shown in Fig. 1, a front fork 1 in one embodiment includes a fork body F having an outer tube 2 and an inner tube 3 inserted axially movably within the outer tube 2, a rod 4 connected to the outer tube 2 and housed within the fork body F, a head member 5 connected to the inner tube 3 and housed within the fork body F, the head member 5 having a rod guide 5a and a lock case 5b, a lock piece 6 defining a lock chamber B within the lock case 5b, a coil spring 7 biasing the lock piece 6 in a direction expanding the lock chamber B, a suspension spring 9 interposed between the outer tube 2 and the lock case 5b, a stopper 10 attached to the rod 4, and a stopper ring 8 serving as a retaining member for preventing the lock piece 6 from coming out of the lock case 5b. In the front fork 1 in this embodiment, the lock case 5b, the lock piece 6, the coil spring 7, the stopper ring 8, and the stopper 10 form a hydraulic locking mechanism L that prevents the front fork 1 from contracting when it is fully compressed.

[0014] 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. When the front fork 1 contracts due to vibrations input from the road surface while the saddle-riding type vehicle is traveling, the damping force generated by the shock absorber D suppresses vibrations of the vehicle body.

[0015] Below, we will explain in detail each part of the front fork 1. The fork body F includes an outer tube 2 and an inner tube 3 that is 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).

[0016] 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 inside 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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 expansion-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.

[0021] 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.

[0022] 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 only the flow of liquid from the extension-side chamber R1 to the compression-side chamber R2, and provides resistance to the flow of liquid, and a compression-side passage 14b that communicates between the compression-side chamber R2 and the extension-side chamber R1, and allows only the flow of liquid from the compression-side chamber R2 to the extension-side chamber R1.

[0023] The partition 16 also has a compression side damping passage 16a that connects the compression side chamber R2 with 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 with the compression side chamber R2, allowing only the flow of liquid from the liquid reservoir chamber R to the compression side chamber R2.

[0024] The bottom cap 15 of the shock absorber D is fixed to the lower end of the cylinder 11 and has a threaded hole 15b opening from the bottom end. The axle bracket 12, which is attached by screw connection to the outer periphery of the lower end of the inner tube 3, 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 bolts 17 that are inserted into the bolt insertion holes 12b of the axle bracket 12 and screwed into the threaded holes 15b of the bottom cap 15. When the bottom cap 15 is fastened to the axle bracket 12 by the bolts 17, the cylinder 11 is connected to the inner tube 3.

[0025] 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 by the movement of the piston 14 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, and the shock absorber D generates 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.

[0026] 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.

[0027] Next, we will explain the hydraulic locking mechanism L. As described above, in the front fork 1 of this embodiment, the hydraulic locking mechanism L is made up of the lock case 5b, the lock piece 6, the coil spring 7, the stopper ring 8, and the stopper 10.

[0028] The head member 5 is annular, and its outer periphery is screwed to the inner periphery of the cylinder 11, thereby fixing it to the cylinder 11. The head member 5 is equipped with an annular rod guide 5a that is movable in the axial direction relative to the rod 4 and slides against the outer periphery of the rod 4 to guide the movement of the rod 4, and a cylindrical lock case 5b that rises upward from the rod guide 5a toward the opposite side from the cylinder and is positioned on the outer periphery of the rod 4. In this way, the head member 5 is attached to the cylinder 11, and is connected to the inner tube 3 via the cylinder 11 and housed in the fork body F.

[0029] As shown in FIG. 2, the rod guide 5a includes 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 includes a recess 5a3 on the inner periphery of the lock case side end, which is the upper end in FIG. 2. The recess 5a3 includes a flat, annular bottom surface 5a31 formed circumferentially on the inner periphery of the lock case side end of the rod guide 5a, and a tapered, inclined surface 5a32 that continues from the outer periphery of the bottom surface 5a31, forming a funnel-shaped recess. The inclined surface 5a32 may be a tapered surface that gradually deepens toward the bottom surface 5a31, or it may be a curved surface.

[0030] The lock case 5b includes a cylindrical portion 5b1, a flange 5b2 that protrudes radially inward from the lower end of the cylindrical portion 5b1 (as viewed in Figure 2), which is the cylinder side, and connects to the outer periphery of the upper end of the rod guide 5a, an orifice hole 5b3 that communicates between the inside and outside of the cylindrical portion 5b1, and a plurality of notched grooves 5b4 provided at the upper end of the cylindrical portion 5b1. An annular groove 5b5 is provided along the circumferential direction on the inner periphery of the cylindrical portion 5b1 at the upper end (as viewed in Figure 2) of the lock case 5b. The lock case 5b is located below the liquid level in the liquid reservoir chamber R and is constantly immersed in the liquid.

[0031] When the rod guide 5a is screwed to the upper end of the cylinder 11, the flange 5b2 comes into contact with the upper end of the cylinder 11, restricting the head member 5 from entering the cylinder 11 and positioning the rod guide 5a in the axial direction relative to the cylinder 11. The inner diameter of the cylindrical portion 5b1 of the lock case 5b is sufficiently larger than the outer diameter of the rod 4, and the rod 4 is inserted into the lock case 5b. The lock case 5b is disposed on the outer periphery of the rod 4 and can move axially together with the cylinder 11 relative to the rod 4.

[0032] Furthermore, when fastening the bottom cap 15 and axle bracket 12 with the bolt 17, the bolt 17 can be rotated while a jig is inserted into the notch groove 5b4 to prevent the cylinder 11 from rotating, which makes it easier to fasten the bolt 17 and also makes it easier to manage the tightening torque of the bolt 17.

[0033] A lock piece 6 is slidably inserted into the cylindrical portion 5b1 of the lock case. 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 within the cylindrical portion 5b1.

[0034] Specifically, as shown in FIGS. 2 and 3, the lock piece 6 includes 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 FIG. 2, a plurality of notches 6c opening from the inner periphery of the bottom portion 6a in FIG. 3 and extending radially, and a tapered surface 6d provided on the outer periphery of the lower end of the cylindrical portion 6b in FIG. 2.

[0035] When the lock piece 6 is housed in the lock case 5b with the cylindrical portion 6b facing the cylinder side, it defines a lock chamber B on the cylinder 11 side within the lock case 5b, and communicates the lock chamber B with the liquid reservoir chamber R outside the lock case 5b through a passage P formed by notches 6c on the inner periphery of the bottom 6a. Four notches 6c are provided on the bottom 6a and are formed in a fan shape.

[0036] 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 5b, guided by the inner circumference of the cylindrical portion 5b1, without axial wobble.

[0037] The tapered surface 6d of the lock piece 6 is formed on the outer periphery of the lower end of the cylindrical portion 6b in FIG. 2, which is the lock case side end, and is a surface that slopes so that the outer diameter becomes smaller as it approaches the lower end on the lock case side.

[0038] A C-shaped stopper ring 8 is fitted in the annular groove 5b5 of the cylindrical portion 5b1 of the lock case 5b. The inner diameter of the stopper ring 8 is smaller than the outer diameter of the lock piece 6, and when the stopper ring 8 is fitted in the annular groove 5b5 after the lock piece 6 is inserted into the lock case 5b, it prevents the lock piece 6 from slipping out of the lock case 5b.

[0039] A coil spring 7 is also housed within the lock case 5b. The coil spring 7 is interposed in a compressed state between the bottom surface 5a31 of the recess 5a3 of 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 5b in a direction that expands the lock chamber B. Therefore, the lock piece 6 is biased by the coil spring 7, and when no external force is applied, it is positioned in a position (initial position) where it abuts against the lower end of the stopper ring 8 relative to the lock case 5b. When the lock piece 6 is positioned in a position where it abuts against the stopper ring 8, 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 5b3 in the lock case 5b and does not block the orifice hole 5b3. 2 relative to the lock case 5b from a state in which it is positioned to abut against the stopper ring 8, the entire tapered surface 6d faces the orifice hole 5b3, and as the lock piece 6 moves downward, the degree of communication between the orifice hole 5b3 and the lock chamber B gradually decreases. When the lock piece 6 further moves downward and the outer peripheral surface of the cylindrical portion 6b above the tapered surface 6d faces the orifice hole 5b3, the degree of opening of the orifice hole 5b3 decreases, and as the lock piece 6 continues to move downward, the orifice hole 5b3 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 5b3, the orifice hole 5b3 is closed. In this way, the orifice hole 5b3 is provided within the sliding range of the lock piece 6 in the lock case 5b, and is blocked by the outer peripheral surface of the lock piece 6 when the lock piece 6 moves from its initial position in the direction of entering the lock case 5b.

[0040] Next, the inner diameter of the coil spring 7 is slightly larger than the outer diameter of the rod 4, and it is guided in extension and contraction by the rod 4 to prevent radial displacement. The outer diameter of the coil spring 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 coil spring 7 in Figure 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.

[0041] Therefore, when the coil spring 7 is housed together with the lock piece 6 in the lock case 5b, the lower end of the coil spring 7 is aligned along the inclined surface 5a32 of the recess 5a3 and positioned to abut against the bottom surface 5a31. Therefore, when the lock piece 6 is inserted into the lock case 5b and the stopper ring 8 is attached to the lock case 5b, the coil spring 7, which is inaccessible from outside the lock case 5b, can be positioned at an appropriate position to abut against the bottom surface 5a31 of the recess 5a3. When the lock piece 6, stopper ring 8, and coil spring 7 are assembled to the head member 5 in this way, the coil spring 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 coil spring 7, which has a small clearance between it and the rod 4, and a situation in which the coil spring 7 interferes and prevents the rod 4 from being unable to be inserted.

[0042] The outer diameter of the coil spring 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. In other words, the tips of each of the notches 6c that open from the inner periphery of the bottom 6a of the lock piece 6 and extend radially are positioned radially outward of the position where the coil spring 7 of the lock piece 6 abuts, so that each notch 6c is not blocked even when the coil spring 7 abuts the inner periphery of the bottom 6a of 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 flatten them and improve seating. Therefore, by making the circumferential length of the flat portions at the ends of the spring member 7 longer than the circumferential length of the notches 6c, it is possible to prevent the ends of the spring member 7 from protruding outside the lock chamber B through the notches 6c, and a stable biasing force can be applied to the lock piece 6.

[0043] Therefore, even if the upper end of the coil spring 7 in FIG. 2 abuts against the inner peripheral side of the lower end of the bottom portion 6 a of the lock piece 6 in FIG. 2, the passage P formed by the notch 6 c is not entirely blocked, and communication between the lock chamber B and the liquid reservoir chamber R is ensured via the passage P.

[0044] 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, it 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 suspension spring 9 and the inner diameter of the stopper ring 8, allowing it to enter the stopper ring 8 and the lock case 5b. 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 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.

[0045] The shape and structure of the stopper 10 can be modified as long as it can enter the stopper ring 8 and the lock case 5b 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, a hole penetrating the bottom 6a may be formed instead of the notch 6c as long as it can be closed when the stopper 10 abuts against it.

[0046] 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.

[0047] 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 lock case 5b. 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 urges the fork body F in a direction that extends it. Therefore, when the front fork 1 is interposed between the body and the front wheel of a saddle-ride type vehicle, the suspension spring 9 exerts a resilient force to elastically support the body. Note that it is sufficient for the suspension spring 9 to constantly urge the fork body F in the extension direction, so it is sufficient for one end to be supported by a portion of the fork body F and the other end to be supported by the lock case 5b.

[0048] 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 smaller than the inner diameter of the lock case 5b. The outer diameter of the suspension spring 9 at the lower end in FIG. 2 is larger than the inner diameter of the lock case 5b, so that the lower end of the suspension spring 9 is directly supported by the upper end in FIG. 2 of the lock case 5b. The outer diameter of the suspension spring 9 is slightly smaller than the inner diameter of the inner tube 3, so that the outer circumference of the suspension spring 9 is centered with the inner circumference of the inner tube 3, preventing radial eccentricity of the suspension spring 9. If the lock case 5b is made of aluminum, an annular sheet may be interposed between the suspension spring 9 and the lock case 5b to protect the lock case 5b from the suspension spring 9.

[0049] 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.

[0050] 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) relative to the lock case 5b together with the stopper 10. When the front fork 1 extends or retracts, the shock absorber D, which extends or retracts together with the fork body F, generates a damping force to suppress vibration of the vehicle body.

[0051] 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 stopper ring 8 inside the lock case 5b and does not move, allowing the rod 4 to move freely in the vertical direction in Figure 2 relative to the lock case 5b and the lock piece 6. Therefore, in this case, the hydraulic locking 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.

[0052] On the other hand, when the front fork 1 is retracted, it moves close to the stroke end on the retraction side, and as shown in Figure 4, when the stopper 10 abuts against the lock piece 6, the passage P provided in the bottom 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 5b together with the rod 4, will try to move the lock piece 6 into the lock case 5b.

[0053] As a result, the coil spring 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 5b, compressing the lock chamber B and causing the liquid in the lock chamber B to pass through the orifice hole 5b3 and move into the liquid reservoir chamber R. The orifice hole 5b3 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 5b. 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 exerts a resistance force in addition to the damping force generated by the shock absorber D, preventing its own compression operation. Although the outer diameter of the stopper 10 is smaller than the inner diameter of the suspension spring 9, the outer diameter of the lock piece 6, which moves inside the lock case 5b together with the stopper 10 and compresses the lock chamber B, is larger than the inner diameter of the suspension spring 9, ensuring a large pressure-receiving area of ​​the lock piece 6 that receives the pressure of the lock chamber B, so the front fork 1 can exert a large resistance force without having to increase the outer diameter.

[0054] Furthermore, as the front fork 1 continues to retract, the lock piece 6 gradually closes the orifice hole 5b3, 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 5b3, the lock chamber B is closed. When the lock piece 6 then tries to move into the lock case 5b, the pressure in the lock chamber B rises even further, causing the front fork 1 to stop retracting toward the stroke end.

[0055] 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 finally 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.

[0056] 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 5b 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 to the lock chamber B. As a result, the lock piece 6 can move freely relative to the lock case 5b and returns to its initial position in accordance with the biasing force of the coil spring 7.

[0057] 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 head member 5 connected to the other of the outer tube 2 and the inner tube 3 and housed within the fork body F, the head member 5 having an annular rod guide 5a which is movable in the axial direction relative to the rod 4 and comes into sliding contact with the outer periphery of the rod 4 to guide the movement of the rod 4; and a cylindrical lock case 5b which rises from the rod guide 5a and is disposed on the outer periphery of the rod 4; and a lock chamber B defined within the lock case 5b, the lock chamber B having a passage P which communicates between the inside and outside of the lock chamber B. a coil spring 7 interposed between the lock case 5b and the lock piece 6 and biasing the lock piece 6 in a direction that expands the lock chamber B; a suspension spring 9 disposed on the outer periphery of the rod 4 and having one end supported by a part of the fork body F and the other end supported by an end of the lock case 5b; and a spring 9 attached to the rod 4 and movable in the axial direction within the suspension spring 9, which moves in a direction approaching the lock case 5b and abuts against the lock piece 6, blocking the passage P and The rod guide 5a has a recess 5a3 having a flat annular bottom surface 5a31 formed circumferentially on the inner periphery of the lock case 5 and an inclined surface 5a32 continuing from the outer periphery of the bottom surface 5a31, and the coil spring 7 is supported by the bottom surface 5a31 of the rod guide 5a.

[0058] 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 can be increased to generate a large resistance force when the front fork 1 is fully retracted, preventing the front fork 1 from bottoming out. With the front fork 1 configured in this manner, the coil spring 7 is aligned by the inclined surface 5a32 of the recess 5a3 of the rod guide 5a, so that the coil spring 7 is positioned in a predetermined position within the lock case 5b, which is not visible from the outside, after the hydraulic locking mechanism L is assembled. This makes it easy to insert the rod 4 into the coil spring 7 even if the clearance between the inner circumference of the coil spring 7 and the outer circumference of the rod 4 is small. Furthermore, the stopper ring 8 prevents the lock piece 6 from slipping out, so that the lock piece 6 will not fall out of the lock case 5b even if the opening of the lock case 5b is turned downward during assembly of the front fork 1, facilitating the process of fastening the shock absorber D and the inner tube 3 with the bolt 17. As described above, the front fork 1 of this embodiment facilitates assembly while increasing the resistance force of the hydraulic locking mechanism L.

[0059] The lock piece 6 is prevented from falling out of the lock case 5b by a stopper ring 8 fixed to the lock case 5b. Therefore, it does not need to slide against the outer periphery of the rod 4, and therefore can move smoothly axially within the lock case 5b without interference from the rod 4. Furthermore, because the coil spring 7 is aligned by the rod 4, the coil spring 7 does not exert a biased radial force on the lock piece 6. This also allows the lock piece 6 to move smoothly axially, and there is no need to provide an alignment portion on the lock piece 6 to align the coil spring 7. The number and shape of the notches 6c forming the passage P can be changed as desired depending on the flow area of ​​the passage P. While the front fork of this embodiment uses a stopper ring 8 as the retaining member, it need not be annular as long as it abuts against the lock piece 6 to prevent it from falling out of the lock case 5b. It may instead be a protrusion formed by crimping a portion of the tubular portion 5b1 of the lock case 5b from the outside and deforming it inward. Furthermore, the stopper ring 8 serving as a retaining member has a circular cross section in the illustrated example, but may have a rectangular cross section.

[0060] As described above, the rod guide 5a has the recess 5a3 including a flat, annular bottom surface 5a31 formed along the circumferential direction on the inner periphery inside the lock case 5 and an inclined surface 5a32 continuing from the outer periphery of the bottom surface 5a31, and the coil spring 7 is supported by the bottom surface 5a31 so that the coil spring 7 is aligned by the inclined surface 5a32 of the recess 5a3, but instead of providing the recess 5a3 in the rod guide 5a, the lock piece 6 may be provided with a recess including a flat, annular bottom surface formed along the circumferential direction on the inner periphery inside the lock case 5 and an inclined surface continuing from the outer periphery of the bottom surface, and the spring member 7 may be supported by the bottom surface of the recess in the lock piece 6. In this case, the spring member 7 is aligned by the inclined surface of the lock piece 6, making it easier to insert the rod 4 into the coil spring 7. Furthermore, in addition to providing the recess 5a3 in the rod guide 5a, the lock piece 6 may be provided with a recess having a flat annular bottom surface formed circumferentially on the inner periphery of the lock case 5 and an inclined surface continuing to the outer periphery of the bottom surface, so that the spring member 7 is supported by the bottom surface 5a31 of the rod guide 5a and the bottom surface of the lock piece 6. In this case, the spring member 7 is aligned by the inclined surface 5a32 of the lock case 5a and the inclined surface of the lock piece 6, making it easier to insert the rod 4 into the coil spring 7.

[0061] Furthermore, the expansion and contraction of the coil spring 7 in the front fork 1 of this embodiment is guided by the rod 4. With the front fork 1 configured in this manner, even if a guide portion for guiding the coil spring 7 is not provided on the lock piece 6, the coil spring 7 is guided by the rod 4 and does not become eccentric with respect to the lock piece 6, so the structure of the lock piece 6 is simple and can be manufactured inexpensively.

[0062] Furthermore, in the front fork 1 of this embodiment, the lock case 5b has an orifice hole 5b3 within 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. 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 5b 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 retraction stroke, effectively mitigating the impact at the time of maximum retraction.

[0063] Furthermore, in the front fork 1 of this embodiment, 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 periphery of the position of contact of the coil spring 7 of the lock piece 6. With the front fork 1 configured in this manner, the passage P is not entirely blocked even when the upper end of the coil spring 7 in Figure 2 contacts 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 coil spring 7 is assembled in the correct position and whether any coil spring 7 has been forgotten to be inserted, thereby improving work efficiency when assembling the front fork 1.

[0064] 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.

[0065] DESCRIPTION OF SYMBOLS 1: Front fork, 2: Outer tube, 3: Inner tube, 4: Rod, 5a: Rod guide, 5a3: Recess, 5a31: Bottom surface, 5a32: Inclined surface, 5b: Lock case, 5b3: Orifice hole, 6: Lock piece, 6c: Notch, 6d: Tapered surface, 7: Coil spring, 8: Stopper ring (preventive member), 9: Suspension spring, 10: Stopper, B: Lock chamber, F: Fork body, P: Passage

Claims

1. A front fork comprising: a fork body having an outer tube and an inner tube inserted into the outer tube so as to be axially movable; a rod connected to one of the outer tube and the inner tube and housed within the fork body; a head member having: an annular rod guide connected to the other of the outer tube and the inner tube and housed within the fork body, the rod being axially movable relative to the rod and sliding against the outer periphery of the rod to guide movement of the rod; and a cylindrical lock case rising from the rod guide and placed on the outer periphery of the rod; a lock piece having an annular inner diameter larger than the outer diameter of the rod, the rod being inserted into its inner periphery and its outer periphery being in sliding contact with the inner periphery of the lock case so as to be axially movable relative to the lock case, defining a lock chamber within the lock case and having a passage communicating the inside and outside of the lock chamber; and a coil spring interposed between the lock case and the lock piece and biasing the lock piece in a direction that expands the lock chamber. a suspension spring 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 an end of the lock case; a stopper attached to the rod, movable in the axial direction within the suspension spring, which moves in a direction approaching the lock case and abuts against the lock piece, thereby closing the passage and pushing the lock piece into the lock case; and a retaining member attached to the inner periphery of the lock case and preventing the lock piece from coming out of the lock case, wherein at least one of the rod guide and the lock piece has a recess having a flat annular bottom surface formed along the circumferential direction on the inner periphery of the lock case and a sloped surface continuing from the outer periphery of the bottom surface, and the coil spring is supported by the bottom surface.

2. A front fork according to claim 1, wherein the coil spring is guided in its expansion and contraction by the rod.

3. A front fork as set forth in claim 1, wherein the lock case has an orifice hole within 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 approaches the lock case side.

4. A front fork as set forth in claim 1, wherein the passage is formed by a notch that opens from the inner periphery of the lock piece, extends radially, and has a tip that is positioned outer circumferentially of the lock piece relative to the position where the coil spring abuts.

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