Suspension device

Abstract

The suspension device (1) includes: a fork frame member (2); and a bracket (3) for gripping the outer periphery of the upper end of the fork frame member (2); the bracket (3) includes: a C-shaped clamp (5) for gripping the fork frame member (2) and having a plurality of through holes (5a1), (5a1), (5b1), (5b2) arranged vertically at both ends; and a plurality of bolts (9), (9) for inserting through the through holes (5a1), (5a1), (5b1), (5b2) provided at both ends of the clamp (5) to pull the two ends of the clamp (5) closer to each other and reduce the diameter of the clamp (5); the outer periphery of the upper end of the fork frame member (2) has a plurality of grooves (2a1), (2a2) for allowing at least one of the bolts (9), (9) formed at different positions in the vertical direction to engage.

Description

[Technical Field]

[0001] This invention relates to a suspension device used in a straddle-type vehicle. [Previous Technology]

[0002] It is known that a suspension device includes: a pair of fork frame members that serve as the steering wheel, i.e., front wheel support, of a motorcycle; and a bracket that holds the upper end of the fork frame members and is connected to the lower end of the steering shaft, wherein the steering shaft is rotatably held in the head tube located at the front end of the motorcycle body.

[0003] The bracket, for example, disclosed in JPH6-270874A, includes: a shaft retaining ring fitted around the outer periphery of a steering shaft connected to a handlebar; a pair of clamps gripping the upper ends of each fork frame member; and a pair of arms connecting the C-shaped clamps positioned on the left and right sides to the central shaft retaining ring with the shaft retaining ring in the center. Furthermore, the clamps include: a pair of holes through which upper and lower allowable bolts are inserted at one end; and a pair of threaded holes at the other end, each facing the aforementioned holes, allowing threaded engagement of the bolts; by inserting two bolts into the corresponding holes and rotating them into the threaded holes, the clamps can be reduced in diameter and clamped tightly around the outer periphery of the fork frame member. [Prior Art Documents] [Patent Documents] [Patent Document 1] JPH6-270874A [Summary of the Invention]

[0004] [Problem to be solved by the invention] As mentioned above, in the conventional suspension device, the two ends of the clamp in the bracket are brought close to each other by the threaded connection of two bolts, and the clamp clamps the outer periphery of the upper end of the fork frame member to connect the bracket and the fork frame member. However, if the clamp only clamps the outer periphery of the fork frame member, the fork frame member may be loosened from the clamp or deviate upward by the input of vibration from the front wheel.

[0005] Therefore, an annular groove along the circumferential direction is provided on the outer periphery of the upper end of the fork frame component. When the fork frame component is clamped by the clamp, the bolts on the upper side of the bolts installed in the clamp are engaged in the annular groove to prevent the fork frame component from being loosened from the clamp.

[0006] In this way, it is possible to prevent the fork frame components from coming loose from the clamp and deviating. Even if the installation position of the clamp on the fork frame components is to be changed in order to accommodate the size of the front wheel and other specifications suitable for a motorcycle, it is necessary to change the design of the parts that make up the upper part of the fork frame components because it is necessary to insert the bolt into the annular groove. Therefore, it is not possible to change the installation position of the clamp to accommodate a motorcycle.

[0007] The object of this invention is to provide a suspension device that prevents forklift components from detaching from the clamp, and also allows for adjustments to the mounting position of the forklift components relative to the clamp to accommodate different specifications of motorcycle-type vehicles. [Technical means to solve the problem]

[0008] In order to solve the above-mentioned problems, the suspension device of the present invention includes: a fork frame member for supporting the front wheel of a straddle-type vehicle; and a bracket for gripping the outer periphery of the upper end of the fork frame member and being connectable to a steering shaft; the bracket includes: a C-shaped clamp for gripping the fork frame member and having a plurality of through holes arranged vertically at both ends; and a plurality of bolts for inserting through the through holes provided at both ends of the clamp, thereby reducing the diameter of the clamp by pulling the two ends of the clamp closer to each other; the fork frame member has a plurality of grooves formed at different vertical positions on the outer periphery of the upper end to allow at least one of the bolts to engage.

[0009] With a suspension device of such structure, the fork frame member can be prevented from detaching from the clamp by engaging any of the multiple grooves of the bolt with the fork frame member, and the installation position of the fork frame member relative to the clamp can be changed by selecting the groove in which the bolt engages among the multiple grooves.

[0010] Furthermore, another suspension device of the present invention includes: a fork frame member for supporting the front wheel of a straddle-type vehicle; and a bracket for gripping the outer periphery of the upper end of the fork frame member and being connectable to a steering shaft; the bracket includes: a C-shaped clamp for gripping the fork frame member and having a plurality of through holes arranged vertically at both ends; and a plurality of bolts for inserting through the through holes provided at both ends of the clamp, thereby reducing the diameter of the clamp by pulling the two ends of the clamp closer together; the fork frame member has a spiral groove formed in at least one of the upper end peripheral allowable bolts.

[0011] With a suspension device of this structure, the fork frame member can be prevented from detaching from the clamp by engaging the bolts in the grooves of the fork frame member, and the installation position of the clamp on the fork frame member can be changed by changing the engagement position of the bolts in the grooves. Furthermore, since a spiral groove is formed on the outer periphery of the upper end of the fork frame member, the installation position of the clamp on the fork frame member can be continuously adjusted as long as it is within the range where the groove is provided.

Implementation Method

[0013] Hereinafter, the present invention will be described based on the embodiments shown in the figures. As shown in Figure 1, the suspension device 1 in one embodiment includes: a pair of fork frame members 2, 2, supporting the front wheel W of a motorcycle V; and a bracket 3, which holds the outer periphery of the upper end of the fork frame members 2, 2 and is configured to be connected to the steering shaft S. Furthermore, in this book, unless otherwise stated, the directions of front-back, left-right, and up-down are described with reference to the motorcycle V.

[0014] The fork frame components 2 and 2, as shown in Figures 1 and 2, all have the same structure. In this embodiment, they include: a cylindrical outer tube 2a disposed on the vehicle body side; and a cylindrical inner tube 2b that enters and exits the outer tube 2a from its lower end and is disposed on the axle side; a damping cylinder (not shown) that is installed between the outer tube 2a and the inner tube 2b, generating a damping force when the inner tube 2b moves relative to the outer tube 2a in the axial direction; and a suspension spring that is installed between the outer tube 2a and the inner tube 2b, forming a structure that pushes the outer tube 2a and the inner tube 2b apart in the axial direction. Therefore, when the suspension device 1 is installed between the vehicle body and the front wheel W of the motorcycle V, the vehicle body can be elastically supported by the suspension spring, and can extend and retract by the input of vibration during the movement of the motorcycle V, thereby exerting a damping force to reduce the vibration.

[0015] Furthermore, the fork frame component 2 may have an outer tube 2a and an inner tube 2b, and may be telescopic and may generate a damping force during telescopic movement. However, it may also have a structure that only houses the suspension spring inside and does not exert a damping force but only elastically supports the vehicle body. As long as it can support the front wheel W, a non-telescopic rod-shaped component may also be used.

[0016] As shown in Figure 2, grooves, i.e. annular grooves 2a1 and 2a2, are arranged in a vertical direction near the upper end of the outer tube 2a on the upper side of the fork frame component 2.

[0017] The steering shaft S is inserted into the head tube P of the motorcycle body and is fitted into a ball bearing mounted on the inner circumference of the head tube P, allowing it to rotate about the head tube P. The upper end of the steering shaft S protrudes upward from inside the head tube P, and the lower end protrudes downward from inside the head tube P. The upper end of the steering shaft S is connected to the handlebar H, allowing the steering shaft S to rotate about the head tube P when the handlebar H is operated.

[0018] The bracket 3, as shown in Figure 1, is connected to: a steering shaft S, which is inserted into the head tube P located at the front end of the body B in the motorcycle V and is rotatably held in the head tube P; and the upper ends of a pair of fork frame members 2, 2, which are arranged on the left and right sides of the front wheel W of the motorcycle V and the axle of the front wheel W is held by the lower ends of the pair of fork frame members 2, 2.

[0019] Specifically, the bracket 3, as shown in Figures 1, 3 to 5, includes: a shaft retaining ring 4 for holding the steering shaft S, a pair of left and right clamps 5 and 6 for gripping the upper ends of each fork frame member 2, 2, a pair of arms 7 and 8 for connecting the shaft retaining ring 4 and each clamp 5, 6, and bolts 9 for threaded engagement with each clamp 5, 6.

[0020] The shaft retaining ring 4 is annular and has an inner diameter that is slightly smaller than the outer diameter of the lower end of the steering shaft S. The shaft retaining ring 4 is press-fitted into the lower end of the steering shaft S to hold the lower end of the steering shaft S.

[0021] Arms 7 and 8, as shown in Figure 3, connect the shaft retaining ring 4 and clamps 5 and 6 with the shaft retaining ring 4 located in the center. That is, arm 7 connects the shaft retaining ring 4 and the clamp 5 on the right side, and arm 8 connects the shaft retaining ring 4 and the clamp 6 on the left side.

[0022] As shown in Figure 3, clamps 5 and 6 are both formed into a C-shape with a broken ring when viewed from above. The clamps 5 and 6 are arranged on the left and right sides of the shaft retaining ring 4 with the shaft retaining ring 4 in the center.

[0023] The clamp 5 of the shaft retaining ring 4, which is positioned on the right side in FIG3, as shown in FIG3 and FIG4, has ears 5a and 5b that protrude radially outward from both ends of the broken portion in the circumferential direction. The ear 5a provided at one end of the clamp 5 in the circumferential direction and the ear 5b provided at the other end of the clamp 5 in the circumferential direction are positioned facing each other to clamp the broken portion of the clamp 5. The clamp 6 of the shaft retaining ring 4, which is positioned on the left side in FIG3, as shown in FIG3 and FIG4, has ears 6a and 6b that protrude radially outward from both ends of the broken portion in the circumferential direction. The ear 6a provided at one end of the clamp 6 in the circumferential direction and the ear 6b ​​provided at the other end of the clamp 5 in the circumferential direction are positioned facing each other to clamp the broken portion of the clamp 6.

[0024] As shown in FIG4, in the ear portion 5a located at the end that becomes the central side of the shaft retaining ring 4, there are two threaded holes 5a1 and 5a2 provided above and below for threaded engagement with the bolt 9. In the ear portion 5b located at the end that becomes the outer side of the shaft retaining ring, there are two through holes 5b1 and 5b2 provided above and below for the bolt 9 to be inserted.

[0025] The threaded hole 5a1 on the upper side of the ear portion 5a and the threaded hole 5b1 on the upper side of the ear portion 5b facing the ear portion 5a are arranged in a group to clamp the aforementioned broken portion and face each other, allowing a bolt 9 to be inserted through. Furthermore, the threaded hole 5a2 on the lower side of the ear portion 5a and the threaded hole 5b2 on the lower side of the ear portion 5b facing the ear portion 5a are arranged in a group to clamp the aforementioned broken portion and face each other, allowing a bolt 9 to be inserted through.

[0026] Therefore, the bolts 9 and 9, which are mounted on the ears 5a and 5b of the clamp 5 and have threaded holes 5a1 and 5a2 and insertion holes 5b1 and 5b2 inserted through them, can shorten the distance between the ears 5a and 5b and reduce the inner diameter of the clamp 5 by rotating them into the opposing threaded holes 5a1 and 5a2. Therefore, by inserting the upper end of the fork frame member 2 into the clamp 5 and then reducing the diameter of the clamp 5 by using bolts 9 and 9 as described above, the clamp 5 can clamp the upper outer periphery of the fork frame member 2 and hold the fork frame member 2.

[0027] Furthermore, in the threaded holes 5a1 and 5a2 in the ear 5a, the upper threaded hole 5a1 is positioned closer to the center of the clamp 5 in the radial direction than the threaded hole 5a2. Similarly, in the through holes 5b1 and 5b2 in the ear 5b, the upper through hole 5b1 is positioned closer to the center of the clamp 5 in the radial direction than the through hole 5b2. Therefore, when the clamp 5 is viewed from the axial direction, the bolts 9 that pass through the upper side of the threaded holes 5a1 and 5b1 forming the group are positioned closer to the inner circumference of the clamp 5 than the bolts 9 that pass through the lower side of the threaded holes 5a2 and 5b2 forming the group, so that the side of the upper bolt 9 is mounted on the clamp 5 with its side protruding from the inner circumferential surface of the clamp 5. On the other hand, when viewed from the axial direction, the bolts 9 that pass through the threaded holes 5a2 and through holes 5b2 forming a group are positioned outside the clamp 5 and do not protrude inside the clamp 5.

[0028] Furthermore, the clamp 6, similar to the clamp 5, includes: two threaded holes 6a1 and 6a2, which are through holes, provided on the upper and lower sides of the ear portion 6a at the end that becomes the central side of the shaft retaining ring 4; and two through holes 6b1 and 6b2, provided on the upper and lower sides of the ear portion 6b at the end that becomes the outer side of the shaft retaining ring. Moreover, the threaded hole 6a1 on the upper side and the through hole 6b1 on the upper side form a group, and the threaded hole 6a2 on the lower side and the through hole 6b2 on the lower side form a group, each allowing the bolt 9 to be inserted. The arrangement of the threaded holes 6a1, 6a2 and through holes 6b1, 6b2 in the clamp 6 is symmetrical with respect to the arrangement of the threaded holes 5a1, 5a2 and through holes 5b1, 5b2 in the clamp 5, centered on the shaft retaining ring 4. When the bolt 9 is inserted through the threaded holes 6a1, 6a2 and through holes 6b1, 6b2, the side of the bolt 9 that is inserted through the upper threaded hole 6a1 and through hole 6b1 is positioned within the clamp 6. Therefore, similar to the clamp 5, after inserting the upper end of the fork frame member 2 into the clamp 6, the bolt 9 is inserted through the upper threaded hole 6a1 and through hole 6b1, and the bolt 9 is inserted through the lower threaded hole 6a2 and through hole 6b2. The bolt 9 is then rotated into the threaded holes 6a1 and 6a2 respectively. Because the clamp 6 has a reduced diameter, the clamp 6 can grip the upper outer periphery of the fork frame member 2.

[0029] Next, the steps for connecting the bracket 3 to the fork frame components 2, 2 will be described. First, with the bolts 9, 9 removed, the upper end of the outer tube 2a of the fork frame component 2 is inserted into the clamp 5. At this time, if it is desired to increase the length of the fork frame component 2 protruding downward from the lower end of the clamp 5, the upper end of the outer tube 2a is inserted into the clamp 5 at the height position of the annular groove 2a1 on the upper side of the outer tube 2a, which aligns with the threaded hole 5a1 on the upper side and the through hole 5b1 on the upper side of the ears 5a, 5b.

[0030] Subsequently, the bolt 9 is inserted through the threaded hole 5a1 and through hole 5b1 on the upper side of the ear portions 5a and 5b forming a group, and the bolt 9 is inserted through the threaded hole 5a2 and through hole 5b2 on the lower side of the ear portions 5a and 5b forming a group. In this way, the bolt 9, which is positioned on the upper side of the clamp 5, protrudes into the clamp 5 and fits into the annular groove 2a1 of the outer tube 2a. The bolt 9, which is positioned on the upper side of the clamp 5, protrudes from the inner circumferential surface of the clamp 5, and restricts the vertical movement of the clamp 5 toward the fork frame member 2 as a function to prevent loosening. On the other hand, when the clamp 5 is viewed from the axial direction, the bolt 9, which is inserted through the threaded hole 5a2 and through hole 5b2 forming a group, is positioned outside the clamp 5 and does not protrude into the clamp 5, so the bolt 9 on the lower side will not interfere with the fork frame member 2.

[0031] If the bolts 9, 9, which are installed on the upper and lower parts of the clamp 5, are rotated into the corresponding threaded holes 5a1, 5a2 respectively, the ears 5a, 5b approach each other, causing the clamp 5 to narrow and forcefully grip the outer periphery of the upper end of the fork frame member 2, that is, the upper end of the outer tube 2a, so that the clamp 5 is fixedly connected to the fork frame member 2. As mentioned above, whenever the clamp 5 is connected to the fork frame member 2, because the bolts 9 are engaged in the annular groove 2a1, the clamp 5 can prevent the fork frame member 2 from loosening from the clamp 5 and grip the fork frame member 2. Even if vibration is input from the front wheel W, the position of the fork frame member 2 will not change.

[0032] In order to shorten the length of the fork frame member 2 protruding downward from the lower end of the clamp 5, the upper end of the outer tube 2a is inserted into the clamp 5 by aligning the annular groove 2a2 on the lower side of the outer tube 2a with the threaded hole 5a1 and the through hole 5b1 on the upper side of the ears 5a and 5b, and the bolt 9 on the upper side of the clamp 5 is fitted into the annular groove 2a2 on the lower side. In this way, the fork frame member 2 can be gripped by the clamp 5 to prevent it from slipping, and compared with the case where the clamp 5 and the fork frame member 2 are connected by fitting the bolt 9 on the upper side into the annular groove 2a1 on the upper side, the installation position of the fork frame member 2 relative to the clamp 5 can be offset further downward from the fork frame member 2. Therefore, if the upper bolt 9 is fitted into the lower annular groove 2a2 to connect the clamp 5 and the fork frame member 2, as shown in FIG6, compared with the case where the upper bolt 9 is fitted into the upper annular groove 2a1, the length of the fork frame member 2 protruding downward from the lower end of the clamp 5 can be shortened in the axial direction from the center of the annular groove 2a1 to the center of the annular groove 2a2.

[0033] Except for the reversed arrangement of the ears 5a, 5b, 6a, and 6b, clamps 5 and 6 have the same structure, so clamp 6 is connected to fork frame member 2 in the same manner as clamp 5. Therefore, when clamp 6 is connected to fork frame member 2, the length of fork frame member 2 protruding downward from the lower end of clamp 6 can be adjusted by fitting the bolt 9 on the upper side into either the annular groove 2a1 on the upper side or the annular groove 2b1 on the lower side.

[0034] Furthermore, in the suspension device 1 of this embodiment, the distance between the annular grooves 2a1 and 2a2 is set such that even when the upper bolt 9 is fitted into the annular groove 2a1 on the upper side of the fork frame member 2 to connect the clamps 5 and 6 to the fork frame member 2, the annular groove 2a2 on the lower side where the bolt 9 is not fitted is located above the lower end of the clamps 5 and 6 and is covered by the clamps 5 and 6. Further, in the suspension device 1 of this embodiment, it is set such that even if the uppermost bolt 9 among the plurality of bolts 9 of the clamps 5 and 6 that grip the fork frame member 2 is fitted into the uppermost annular groove 2a1, the lowermost annular groove 2a2 can still be positioned above the lowermost bolt 9.

[0035] The suspension device 1 of this embodiment includes: a fork frame member 2, which supports the front wheel W of the straddle-type vehicle V; and a bracket 3, which holds the outer periphery of the upper end of the fork frame member 2 and can be connected to the steering shaft S; the bracket 3 includes: a C-shaped clamp 5, which holds the fork frame member 2 and has a plurality of threaded holes (through holes) 5a1, 5a1 and through holes 5b1, 5b2 arranged vertically at both ends; and a plurality of bolts 9, 9, which are inserted through the threaded holes (through holes) 5a1, 5a1 and through holes 5b1, 5b2 provided at both ends of the clamp 5, thereby reducing the diameter of the clamp 5 by pulling the two ends of the clamp 5 closer to each other; the fork frame member 2 has a plurality of annular grooves 2a1, 2a2, which are formed at different vertical positions on the outer periphery of the upper end, allowing at least one of the bolts 9, 9 to be engaged.

[0036] According to the suspension device 1 configured in this way, the fork frame member 2 can be prevented from being loosened from the clamp 5 by the bolt 9 engaging with any of the plurality of annular grooves 2a1, 2a2 of the fork frame member 2, and the installation position of the fork frame member 2 relative to the clamp 5 can be changed by selecting the annular groove 2a1, 2a2 in which the bolt 9 engages.

[0037] Therefore, according to the suspension device 1 of this embodiment, the fork frame member 2 can be prevented from detaching from the clamp 5, and the installation position of the clamp 5 on the fork frame member 2 can be changed according to the specifications of the straddle-type vehicle V.

[0038] Furthermore, in the suspension device 1 of this embodiment, the grooves that allow the bolts 9 to engage are annular grooves 2a1 and 2a2. Therefore, when connecting the clamps 5 and 6 to the fork frame member 2, it is not necessary to position the fork frame member 2 in the circumferential direction to engage the bolts 9 with the clamps 5 and 6, thus reducing the workload of connecting the clamps 5 and 6 to the fork frame member 2. However, since the bolts 9 engage and together with the bolts 9 form a groove to prevent the fork frame member 2 from loosening from the clamps 5 and 6, as long as the engagement of the side of the bolts 9 is allowed and the movement of the bolts 9 in the axial direction and the rotation in the circumferential direction within the groove created by the bolts 9 rotating into the threaded holes 5a1 and 6a1 are not hindered, and the gripping of the fork frame member 2 caused by the reduction in diameter of the clamps 5 and 6 is not hindered, it is not necessary for the aforementioned annular grooves 2a1 and 2a2 to form an annular shape across the entire circumference of the fork frame member 2. Therefore, the groove that allows the bolt 9 to engage can be provided along the axis of the bolt 9 on a portion of the outer periphery of the upper end of the fork frame member 2. In this case, although the axis of the bolt 9 is in a torsional position relative to the axis of the fork frame member 2, it is preferable that the groove is provided along the circumferential direction on the outer periphery of the upper end of the fork frame member 2 because it is positioned on a plane orthogonal to the axis of the fork frame member 2. However, as long as the groove allows the bolt 9 to be inserted and does not hinder the bolt 9 from moving in the axial direction or rotating in the circumferential direction, the direction of the groove and the axis of the bolt 9 does not have to be the same, and the bolt 9 can be allowed to move and engage in the groove.

[0039] Further, in this embodiment, the suspension device 1 supports the front wheel W by two fork frame members 2, 2, and the bracket 3 also has two clamps 5, 6 corresponding to the two fork frame members 2, 2. However, when the front wheel W is supported by one fork frame member 2, the bracket 3 can be made to have only one of the clamps 5, 6.

[0040] Furthermore, the grooves for bolt 9 engagement can be provided in three or more stages. As described above, since two annular grooves 2a1 and 2a2 are provided, the installation position of clamps 5 and 6 relative to fork frame members 2 and 2 can be adjusted in two stages, and the length of fork frame members 2 and 2 protruding downwards from clamps 5 and 6 can be adjusted in two stages. However, if the number of grooves is three or more, the installation position of clamps 5 and 6 relative to fork frame members 2 and 2 can be adjusted in three or more stages corresponding to the number of grooves.

[0041] Furthermore, if three or more grooves are provided for the engagement of bolts 9, the spacing between the grooves can be aligned with the axial spacing of the threaded holes 5a1, 5a2, 6a1, 6a2 and the through holes 5b1, 5b2, 6b1, 6b2, so that bolts 9 on both the upper and lower sides can simultaneously engage in the corresponding grooves. Further, three or more bolts 9 may be provided in each of the clamps 5 and 6. In this case, among the three or more bolts 9 arranged vertically, it is possible to arbitrarily determine which bolt 9 engages in the groove.

[0042] Furthermore, as described above, the through hole provided in the ear 5a (6a) may be a threaded hole 5a1, 5a2 (6a1, 6a2), but it may also be a hole without a thread groove. In this case, a nut that is threaded to the threaded shaft of the bolt 9 may be used, and the bolt 9 and the nut may be used to clamp the ear 5a (6a) and the ear 5b (6b) so that the clamp 5 (6) is reduced in diameter, and the clamp 5 (6) may be used to hold the fork frame member 2.

[0043] Furthermore, in the suspension device 1 of this embodiment, the annular grooves 2a1 and 2a2 are necessarily positioned above the lower ends of the clamps 5 and 6 that hold the fork frame member 2. With the suspension device 1 having such a structure, regardless of which annular groove 2a1 or 2a2 the bolt 9 is fitted into, since the annular grooves 2a1 and 2a2 are necessarily positioned above the lower ends of the clamps 5 and 6, even if a bending moment is input from the front wheel W toward the fork frame member 2 during the movement of the straddle-type vehicle V, the weaker part with the weak bending strength provided by the annular grooves 2a1 and 2a2 can be held by the clamps 5 and 6, and a large bending stress will not act on that weak part. Therefore, with a suspension device 1 of such a structure, since the wall thickness of the weak part in the fork frame member 2 does not need to be increased to withstand bending stress, the weight of the fork frame member 2 can be avoided even if the installation positions of the clamps 5 and 6 in the fork frame member 2 are changed.

[0044] Further, in the suspension device 1 of this embodiment, if the uppermost bolt 9 among the plurality of bolts 9, 9 installed on the clamps 5, 6 that hold the fork frame member 2 engages with the uppermost annular groove 2a1 among the annular grooves 2a1, 2a2, the lowermost annular groove 2a2 among the annular grooves 2a1, 2a2 is positioned above the lowermost bolt 9. With a suspension device 1 of this structure, when the fork frame member 2 is gripped by clamps 5 and 6, all the annular grooves 2a1 and 2a2 are positioned above the lowest bolt 9. Therefore, even if a bending moment is input from the front wheel W towards the fork frame member 2 during the movement of the motorcycle V, the weaker, less flexurally strong portion with the annular grooves 2a1 and 2a2 is positioned above the portion clamped by the clamps 5 and 6 via the bolt 9. Thus, the bending stress acting on that weak portion is minimized. Therefore, with a suspension device 1 of this structure, the wall thickness of the weak portion in the fork frame member 2 does not need to be increased to withstand bending stress. Even if the mounting positions of the clamps 5 and 6 in the fork frame member 2 are changed, the weight of the fork frame member 2 can be avoided, thus more effectively preventing any increase in weight.

[0045] Furthermore, in the suspension device 1 of this embodiment, only the uppermost bolt 9 among the plurality of bolts 9, 9 of the clamps 5, 6 that hold the fork frame member 2 is engaged in the annular groove 2a1 (2a2). With the suspension device 1 having such a structure, since only the uppermost bolt 9 among the plurality of bolts 9, 9 is engaged in the annular groove 2a1 (2a2), the position of the annular groove 2a1 (2a2) can be easily grasped based on the amount of protrusion of the fork frame member 2 protruding from the upper end of the clamps 5, 6. Thus, it is easy to change the installation position of the clamps 5, 6 on the fork frame member 2, and when the clamps 5, 6 are installed on the fork frame member 2, it is easy to prevent the annular groove 2a2 on the lower side from protruding downwards from the clamps 5, 6. Thus, by only fitting the uppermost bolt 9 among the plurality of bolts 9 into the annular groove 2a1 (2a2) to prevent the fork frame components 2 and 2 from detaching from the clamps 5 and 6 and the aforementioned changes in installation position, the aforementioned advantages can be enjoyed. However, fitting the lower bolts 9 into the annular groove 2a1 or annular groove 2a2 to prevent the fork frame components 2 and 2 from detaching from the clamps 5 and 6 and adjusting the installation position of the clamps 5 and 6 for the fork frame components 2 and 2 is also possible. In this case, the arrangement of the lugs 5a and 6a of the threaded holes 5a2 and 6a2 on the lower side of the group and the through holes 5b2 and 6b2 on the lower side is located closer to the center of the radial direction of the clamps 5 and 6 than the arrangement of the lugs 5a and 6a of the threaded holes 5a1 and 6a1 on the upper side of the group and the through holes 5b1 and 6b1 on the upper side of the clamps 5 and 6. When the clamps 5 and 6 are viewed from the axial direction, the bolt 9 on the upper side is arranged outside the clamps 5 and 6, while the bolt 9 on the lower side protrudes into the clamps 5 and 6.

[0046] As described above, although the grooves for the engagement of bolts 9 are annular grooves 2a1 and 2a2, as shown in Figure 7, grooves 2a3, 2a4, 2a5, and 2a6 can also be provided along the spiral trajectory on the outer periphery of the upper end of the fork frame component 2. As shown in Figure 7, a set of four grooves 2a3, 2a4, 2a5, and 2a6 are provided along the spiral on the outer periphery of the fork frame component 2, within one spiral turn, and in different directions in the vertical and circumferential directions. Furthermore, a separate set of four grooves 2a7, 2a8, 2a9, and 2a10 are provided above these grooves 2a3, 2a4, 2a5, and 2a6, on the outer periphery of the fork frame component 2, within one spiral turn, and in different directions in the vertical and circumferential directions. The two sets of eight grooves 2a3, 2a4, 2a5, 2a6, 2a7, 2a8, 2a9, and 2a10 are provided within two spiral turns on the outer periphery of the fork frame component 2.

[0047] The first group of grooves 2a3, 2a4, 2a5, and 2a6 are located on the outer periphery of the fork frame member 2 and within one spiral turn, with a 90-degree phase difference in the circumferential direction, and are positioned at different vertical positions. The second group of grooves 2a7, 2a8, 2a9, and 2a10 are located above the area of ​​the first group of grooves 2a3, 2a4, 2a5, and 2a6 on the outer periphery of the fork frame member 2 and within one spiral turn, with a 90-degree phase difference in the circumferential direction, and are positioned at different vertical positions.

[0048] If grooves 2a3, 2a4, 2a5, 2a6 (2a7, 2a8, 2a9, 2a10) are provided on the outer periphery of the upper end of the fork frame component 2 along the spiral trajectory, compared with the case of providing annular grooves 2a1, 2a2, the vertical spacing between adjacent grooves in the circumferential direction and between grooves can be narrowed. By setting grooves 2a3, 2a4, 2a5, 2a6 (2a7, 2a8, 2a9, 2a10) in a position close to each other in the vertical direction of the fork frame component 2, the installation position of clamps 5, 6 on the fork frame component 2 can be adjusted more precisely by selecting the grooves into which bolts 9 are fitted.

[0049] Furthermore, since grooves 2a3, 2a4, 2a5, 2a6, 2a7, 2a8, 2a9, and 2a10 are arranged in a spiral pattern along a spiral trajectory on the outer periphery of the fork frame member 2, if the fork frame member 2 is rotated in the circumferential direction relative to the clamps 5 and 6 in one direction, the grooves that gradually shorten the length of the fork frame member 2 protruding below the clamps 5 and 6 can be aligned with the bolt 9. On the other hand, if the fork frame member 2 is rotated in the circumferential direction relative to the clamps 5 and 6 in the other direction, the grooves that gradually lengthen the length of the fork frame member 2 protruding below the clamps 5 and 6 can be aligned with the bolt 9. Therefore, if grooves 2a3, 2a4, 2a5, 2a6, 2a7, 2a8, 2a9, and 2a10 are arranged in a spiral pattern on the outer periphery of the fork frame member 2, when adjusting the length of the fork frame member 2 protruding downward from the clamps 5 and 6, the clamps 5 and 6 can be oriented towards the rotation direction of the fork frame member 2, whether the length is increased or decreased. This makes it easy to change the installation position of the fork frame member 2 relative to the clamps 5 and 6.

[0050] As shown in FIG8, a spiral groove 2a11 for at least one of the bolts 9 to engage may be provided on the outer periphery of the upper end of the fork frame member 2. In this case, the bolt 9 may be installed with the groove 2a11 tilted so as to be tilted relative to the ears 5a, 5b, 6a, 6b of the clamps 5 and 6. Specifically, the threaded hole 5a1 (6a1) and the through hole 5b1 (6b1) forming a group of insertion holes through which the bolt 9 engages with the groove 2a11 are arranged in such a way that the bolt 9 can be tilted relative to the ears 5a, 5b (6a, 6b) along the groove 2a11. Furthermore, the width of the fork frame member 2 in the vertical direction in the groove 2a11 is set to be wider than the diameter of the bolt 9. Even if the bolt 9 is installed on the ears 5a, 5b, 6a, 6b of the clamps 5 and 6 along the circumferential direction of the fork frame member 2, the bolt 9 may not be along the inclined direction of the groove 2a11 when it is allowed to be inserted through the groove 2a11.

[0051] With the suspension device 1 having such a structure, since a groove 2a11 is formed spirally on the outer periphery of the upper end of the fork frame member 2, the fork frame member 2 can be prevented from detaching from the clamp 5 by engaging the bolt 9 with the groove 2a11. Furthermore, the mounting position of the clamp 5 on the fork frame member 2 can be changed by changing the engagement position of the bolt 9 with the groove 2a11. Moreover, since the groove 2a11 is formed spirally on the outer periphery of the upper end of the fork frame member 2, the mounting position of the clamps 5 and 6 on the fork frame member 2 can be continuously adjusted within the area where the groove 2a11 is provided. Furthermore, when adjusting the length of the fork frame member 2 protruding downward from the clamps 5 and 6, the clamps 5 and 6 can be oriented in the direction of rotation of the fork frame member 2, regardless of whether the length is increased or decreased, making it easy to change the mounting position of the clamps 5 and 6 on the fork frame member 2.

[0052] Although the preferred embodiments of the present invention have been described in detail above, modifications, alterations and changes are possible without departing from the scope of the patent application. [Simplified Explanation of the Diagram]

[0012] [Fig. 1] A diagram showing a straddle-type vehicle to which a suspension device according to an embodiment of the present invention is applied. [Fig. 2] A side view of the upper portion of the fork frame member in a suspension device according to an embodiment of the present invention. [Fig. 3] A top view of the bracket in a suspension device according to an embodiment of the present invention. [Fig. 4] A rear view of the bracket in a suspension device according to an embodiment of the present invention. [Fig. 5] A side view of the bracket in a suspension device according to an embodiment of the present invention. [Fig. 6] A diagram showing the connection state between the clamp of the bracket and the upper end of the fork frame member in a suspension device according to an embodiment of the present invention. [Fig. 7] A perspective view of the upper portion of the fork frame member in a modified embodiment of the suspension device according to an embodiment of the present invention. [Fig. 8] A perspective view of the upper portion of the fork frame member in a first modified embodiment of the present invention.

Claims

1. A suspension device comprising: a fork frame member for supporting the front wheel of a straddle-type vehicle; and a bracket for gripping the outer periphery of the upper end of the fork frame member and being connectable to a steering shaft; the bracket comprising: a C-shaped clamp for gripping the fork frame member and having a plurality of through holes arranged vertically at both ends; and a plurality of bolts for inserting through the through holes provided at the two ends of the clamp, thereby reducing the diameter of the clamp by pulling the two ends of the clamp closer together; the fork frame member having a plurality of annular grooves formed at different vertical positions on the outer periphery of the upper end of the fork frame member, the plurality of annular grooves allowing at least one of the bolts to engage.

2. A suspension device comprising: a fork frame member for supporting the front wheel of a straddle-type vehicle; and a bracket for gripping the outer periphery of the upper end of the fork frame member and being connectable to a steering shaft; the bracket comprising: a C-shaped clamp for gripping the fork frame member and having a plurality of through holes arranged vertically at both ends; and a plurality of bolts for inserting through the through holes provided at the two ends of the clamp, thereby reducing the diameter of the clamp by pulling the two ends of the clamp closer together; the fork frame member having a helical groove formed on the outer periphery of the upper end, the helical groove allowing at least one of the bolts to engage.

3. A suspension device comprising: a fork frame member supporting the front wheel of a straddle-type vehicle; and a bracket holding the outer periphery of the upper end of the fork frame member and connectable to a steering shaft; the bracket comprising: a C-shaped clamp holding the fork frame member and having a plurality of through holes arranged vertically at both ends; and a plurality of bolts inserted through the through holes provided at the two ends of the clamp, thereby reducing the diameter of the clamp by pulling the two ends of the clamp closer together; the fork frame member having a plurality of grooves formed at different vertical positions on the outer periphery of the upper end of the fork frame member, the plurality of grooves allowing at least one of the bolts to engage, the plurality of grooves being provided along a helical trajectory on the outer periphery of the upper end of the fork frame member.

4. A suspension device comprising: a fork frame member supporting the front wheel of a straddle-type vehicle; and a bracket holding the outer periphery of the upper end of the fork frame member and connectable to a steering shaft; the bracket comprising: a C-shaped clamp holding the fork frame member and having a plurality of through holes arranged vertically at both ends; and a plurality of bolts inserted through the through holes provided at the two ends of the clamp, thereby reducing the diameter of the clamp by pulling the two ends of the clamp closer together; the fork frame member having a plurality of grooves formed at different vertical positions on the outer periphery of the upper end of the fork frame member, the grooves allowing at least one of the bolts to engage, the grooves being positioned above the lower end of the clamp holding the fork frame member.

5. A suspension device comprising: a fork frame member for supporting the front wheel of a straddle-type vehicle; and a bracket for gripping the outer periphery of the upper end of the fork frame member and being connectable to a steering shaft; the bracket comprising: a C-shaped clamp for gripping the fork frame member and having a plurality of through holes arranged vertically at both ends; and a plurality of bolts for inserting through the through holes provided at the two ends of the clamp, thereby reducing the diameter of the clamp by pulling the two ends of the clamp closer together; the fork frame member having a plurality of grooves formed at different vertical positions on the outer periphery of the upper end of the fork frame member, the plurality of grooves allowing at least one of the bolts to engage, wherein if the uppermost bolt of the plurality of bolts mounted in the clamp gripping the fork frame member engages with the uppermost groove, the lowermost groove of the plurality of grooves is positioned above the lowermost bolt.

6. A suspension device comprising: a fork frame member for supporting the front wheel of a straddle-type vehicle; and a bracket for gripping the outer periphery of the upper end of the fork frame member and being connectable to a steering shaft; the bracket comprising: a C-shaped clamp for gripping the fork frame member and having a plurality of through holes arranged vertically at both ends; and a plurality of bolts for inserting through the through holes provided at the two ends of the clamp, thereby reducing the diameter of the clamp by pulling the two ends of the clamp closer together; the fork frame member having a plurality of grooves formed at different vertical positions on the outer periphery of the upper end of the fork frame member, wherein at least one of the bolts is engaged in the grooves, and only the uppermost bolt among the plurality of bolts installed in the clamp gripping the fork frame member engages with the groove.

7. The suspension device as described in claim 2, wherein, The aforementioned groove is positioned above the lower end of the aforementioned clamp that grips the aforementioned fork structure component.

8. The suspension device as described in claim 2, wherein, If the uppermost bolt among the plurality of bolts installed in the aforementioned clamp that holds the aforementioned fork structure component engages with the uppermost groove among the aforementioned grooves, the lowermost groove among the aforementioned grooves is positioned above the lowermost bolt.

9. The suspension device as described in claim 2, wherein, Only the uppermost bolt among the plurality of bolts installed in the aforementioned clamp that holds the aforementioned fork structure component engages with the aforementioned groove.

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