JP2008185069A - Front fork - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple-structured front fork capable of positively sealing a bottom face of a lower end side of an axle side tube to a lower face of a lower end of a damper cylinder. <P>SOLUTION: In the front fork 10, an annular projection 101 is provided to one of the bottom face on the lower end side of the axle side tube 11 and the lower face of the lower end of the damper cylinder 21. The lower face of the lower end of the damper cylinder 21 is fastened to the bottom face on the lower end side of the axle side tube 11. The projection 101 is made to completely bite into or made to be squashed against the other one of the bottom face of the lower end of the axle side tube 11 and the lower face on the lower end side of the damper cylinder 21, so that the bottom face and the lower face closely contact each other. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a front fork.

  As described in Patent Documents 1 and 2, as a front fork, a lower end portion of a damper cylinder is erected on the lower end side of an axle side tube, an oil reservoir chamber between the axle side tube and the damper cylinder, and an oil chamber inside the damper cylinder There is one in which an oil passage connecting the two is provided at the lower end portion of the axle side tube, and a damping force generating portion is provided at an intermediate portion of the oil passage.

Further, as described in Patent Document 3, in a rotary damper that attaches a lid to the main body case via an O-ring, an inner surface of the lid that is attached by crimping an end of the main body case and a surface that faces the main body case When the end of the main body case is caulked, the convex portion is crushed or the convex portion bites into the gap between the inner surface of the lid and the surface facing the main body case. There are some which make it possible to adjust the size of the gap formed.
JP2005-180490 JP2001-140967 JP 2006-300088

  In the front fork described in Patent Document 1, an oil passage A extending from an oil chamber inside a damper cylinder to a damping force generation portion and an oil passage B extending from an oil reservoir chamber to the damping force generation portion are provided on the lower end side of the axle side tube. The bottom surface (the bottom surface of the axle bracket 18) and the bottom surface (the seat member 70 and the holder 51) of the lower end of the damper cylinder are sealed. For this reason, if the seal between the bottom surface of the lower end side of the axle side tube and the lower surface of the lower end portion of the damper cylinder lacks certainty, the oil passage A and the oil passage B bypass the damping force generating portion and short-circuit. The damping force of the force generator becomes unstable.

  In the front fork described in Patent Document 2, an oil passage A extending from the oil chamber inside the damper cylinder to the damping force generation portion and an oil passage B extending from the oil reservoir chamber to the damping force generation portion are provided on the lower end side of the axle side tube. Is sealed with an O-ring interposed between the bottom surface (bottom portion 5a) and the lower surface of the lower end portion of the damper cylinder (the leg portion 6a of the oil hole 6). A space for incorporating the O-ring is required, and a man-hour is required for machining and assembling the groove for the O-ring, resulting in high costs.

  The convex part provided in the main body case in the rotary damper described in Patent Document 3 is accompanied by an O-ring and is not for sealing purposes. Since there is a gap between the inner surface of the lid adjusted by the convex portion and the opposing surface of the main body case, the strength of the biting or crushing of the convex portion may progress with time, and the caulking of the main body case and the lid may be loosened. There is also.

  An object of the present invention is to ensure the sealing of the bottom surface on the lower end side of the axle side tube and the lower surface of the lower end portion of the damper cylinder with a simple configuration in the front fork.

  According to the first aspect of the present invention, the lower end portion of the damper cylinder is erected on the lower end side of the axle side tube, and the oil passage connecting the oil reservoir chamber between the axle side tube and the damper cylinder and the oil chamber inside the damper cylinder is provided on the axle side. In the front fork provided at the lower end of the tube and provided with a damping force generating part in the middle of the oil passage, an annular projection is provided on one of the bottom surface on the lower end side of the axle side tube and the lower surface of the lower end portion of the damper cylinder, The lower surface of the lower end of the damper cylinder is fastened to the bottom surface of the lower end side of the axle side tube, and the protrusion is completely bited or crushed by the other of the lower surface of the lower end side of the axle side tube and the lower surface of the lower end portion of the damper cylinder. The bottom surface and the bottom surface are brought into close contact with each other, and an oil passage extending from the oil chamber inside the damper cylinder to the damping force generation portion is disposed inside the annular protrusion, and an oil passage extending from the oil reservoir chamber to the damping force generation portion is formed into the annular protrusion. Outside Those who were placed in.

  According to a second aspect of the present invention, in the first aspect of the present invention, an axle bracket is screwed to the axle side tube, and a lower end portion of the axle side tube is formed by the axle bracket, and a lower end portion of the damper cylinder is connected to the axle side tube. The lower surface of the lower end portion of the damper cylinder is fastened to the bottom surface of the axle bracket.

  According to a third aspect of the present invention, in the second aspect of the present invention, a bottom plate is welded to the damper cylinder, and the bottom plate constitutes a lower end portion of the damper cylinder.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the bottom plate of the damper cylinder is made of a material harder than the axle bracket.

(Claim 1)
(a) By causing the annular protrusion provided on one of the bottom surface on the lower end side of the axle side tube and the lower surface of the damper cylinder to completely bite into the other, or crushing them so that the bottom surface and the lower surface are in close contact with each other Thus, it is possible to ensure the sealing of the bottom and bottom surfaces thereof. At this time, the oil passage extending from the oil chamber inside the damper cylinder to the damping force generating portion is disposed inside the annular protrusion, and the oil passage extending from the oil reservoir chamber to the damping force generating portion is disposed outside the annular protrusion. These oil passages bypass the damping force generator and do not short-circuit, and the damping force of the damping force generator can be stabilized.

  (b) There is no need to insert an O-ring between the bottom surface on the lower end side of the axle-side tube and the lower surface of the lower end portion of the damper cylinder. it can.

  (c) The annular projection provided on one of the bottom surface on the lower end side of the axle side tube and the bottom surface of the damper cylinder is completely bited into or crushed by the other, so that the bottom surface and the bottom surface are completely Adhere to. Therefore, the degree of biting or crushing of the annular protrusion does not progress with time, and the close contact between the bottom surface on the lower end side of the axle side tube and the lower surface of the lower end portion of the damper cylinder does not become unstable. There is no possibility that the axle tube and the axle bracket are loosely screwed.

(Claim 2)
(d) Axle bracket is screwed onto the axle side tube, and the lower end of the axle side tube is constituted by the axle bracket, and the lower end of the damper cylinder is sandwiched between the axle side tube and the axle bracket, thereby The lower surface of the lower end portion of the damper cylinder is fastened to the bottom surface of the damper cylinder, and the annular protrusion provided on one of the bottom surface on the lower end side of the axle tube and the lower surface of the lower end portion of the damper cylinder is completely bited into or crushed by the other. Thus, the bottom surface and the bottom surface can be securely adhered.

(Claim 3)
(e) By welding the bottom plate to the damper cylinder and forming the lower end portion of the damper cylinder with the bottom plate, the bottom plate as the lower end portion of the damper cylinder can be securely fastened between the axle side tube and the axle bracket.

(Claim 4)
(f) The damper cylinder bottom plate is made of a material harder than the axle bracket. Therefore, when the annular protrusion is provided on the lower surface of the bottom plate (hard), the hard annular protrusion can be bitten into the bottom surface of the soft axle bracket. When the annular protrusion is provided on the bottom surface of the axle bracket (soft), the soft annular protrusion can be crushed by the flat surface of the hard bottom plate. In either case, the bottom surface of the axle bracket and the bottom plate can be completely brought into close contact with each other.

  1 is a sectional view showing a front fork, FIG. 2 is an enlarged sectional view of a lower portion of the front fork in FIG. 1, FIG. 3 is an enlarged sectional view of an intermediate portion of the front fork in FIG. FIG. 5 is a sectional view showing a damping force generator provided on an axle bracket and an oil lock collar provided on a damper cylinder. FIG. 6 is a sectional view showing a structural example in which an annular protrusion is provided on the bottom plate of the damper cylinder. 7 is a cross-sectional view showing a structural example in which an annular protrusion is provided on the bottom surface of the axle bracket.

  As shown in FIGS. 1 to 4, the front fork 10 is inverted by fitting a vehicle body side outer tube (vehicle body side tube) 11 to an axle side inner tube (axle side tube) 12 slidably. A suspension spring 13 is interposed between the tubes 11 and 12 and the single cylinder damper 14 is installed upright.

  A bush 15, an oil seal 16, and a dust seal 17 that are in sliding contact with the outer peripheral portion of the inner tube 12 are fitted to the inner peripheral portion of the lower end of the outer tube 11, and the inner peripheral portion of the outer tube 11 is attached to the upper peripheral portion of the inner tube 12. A bush 18 that comes into sliding contact is fitted.

  The outer tube 11 is supported on the vehicle body side via an upper bracket 19A and a lower bracket 19B, and the lower end of the inner tube 12 is inserted into the axle bracket 20 via an O-ring 23 and is screwed together. The bracket 20 is coupled to the axle through the axle hole 20A.

  The lower end of the damper cylinder 21 of the damper 14 is sandwiched between the axle bracket 20 and the lower end of the inner tube 12. That is, the center step hole of the bottom plate 22 is fitted to the lower end of the damper cylinder 21, the periphery of the step hole of the bottom plate 22 is welded to the outer periphery of the lower end of the damper cylinder 21, and the outer periphery of the bottom plate 22 is fitted to the fitting hole 20 B of the axle bracket 20. And is sandwiched between the axle bracket 20 and the lower end of the inner tube 12. The bottom plate 22 includes a central hole 22A (oil passage) communicating with a piston-side oil chamber 43A described later and a plurality of small holes 22B (oil passages) communicating with an oil reservoir chamber 35A described later.

  A cylindrical portion 25A of the cap 25 is liquid-tightly inserted and screwed into the upper end portion of the outer tube 11 via an O-ring 26, and a spring load adjustment adjuster 28 is provided on the inner periphery of the lid portion 25B of the cap 25. It is inserted through the O-ring 27 so as to be liquid-tight and rotatable. A base end portion of a piston rod 29 is screwed to the inner periphery of the lower end of the adjuster 28 and is locked by a lock nut 30. The tip of the piston rod 29 is inserted into the damper cylinder 21.

  A spring receiver 32 is provided at the upper end portion of the damper cylinder 21 inside the inner tube 12. On the other hand, inside the outer tube 11, a collar 28 </ b> A that abuts against the inner lower surface of the lid portion 25 </ b> B of the cap 25 is inserted into the outer periphery on the upper end side of the adjuster 28. At the same time, a screw cylinder 28C held up and down by the collar 28A and the retaining ring 28B is screwed and fixed to the outer periphery of the adjuster 28, and rotates integrally with the adjuster 28. The adjustment plate 28D screwed to the screw cylinder 28C of the adjuster 28 is prevented from rotating between the groove 25C of the cap 25 and supports the upper end of the suspension spring 13 via the slider 33 and the spring collar 34. To support the lower end of the suspension spring 13. By rotating the adjuster 28, the adjustment plate 28D is moved up and down, and the initial load of the suspension spring 13 is set via the spring collar 34.

  Inside the outer tube 11 and the inner tube 12, an oil reservoir chamber 35A and a gas chamber 35B are provided on the outer periphery of the damper cylinder 21, and the gas confined in the gas chamber 35B constitutes a gas spring. The hydraulic oil in the oil reservoir 35A contributes to adjustment of the spring constant of the gas chamber 35B, lubrication of the sliding contact bushes 15 and 18 of the outer tube 11 and the inner tube 12, and wetting of the oil seal 16 at the lower end of the inner tube 12. To do. And the elastic force of these suspension spring 13 and gas spring absorbs the impact force which a vehicle receives from a road surface.

  The damper 14 includes a piston valve device (extension-side damping force generation device) 40 and a bottom valve device (compression-side damping force generation device) 50. The damper 14 suppresses the expansion and contraction vibration of the outer tube 11 and the inner tube 12 due to the absorption of the impact force by the suspension spring 13 and the gas spring by the damping force generated by the piston valve device 40 and the bottom valve device 50.

  A rod guide 36 is caulked and fixed to the upper end opening of the damper cylinder 21, and a bush housing 37A is inserted into and fixed to the rod guide 36 via an O-ring 37B, and is pressed into the bush housing 37A. Thus, the piston rod 29 is slidably guided.

  In addition, a rebound spring 38 is held directly below the rod guide 36 on the inner periphery of the damper cylinder 21 so as to be compressed with a piston holder 41 (to be described later) at the time of maximum extension and perform a buffering action.

  Also, an oil lock collar 70 described later is provided on the bottom side of the damper cylinder 21, and an oil lock piece 80 described later is provided on the tip side of the piston rod 29. It enters 70 and performs a buffering action at the time of the most compression.

Hereinafter, the damping mechanism of the front fork 10 will be described.
(Piston valve device 40)
In the piston valve device 40, a piston holder 41 is mounted on the tip of the piston rod 29, and a piston 42 and a valve stopper 41C are mounted by a nut 41A and a valve stopper 41B that are screwed onto the piston holder 41. The piston 42 slidably contacts the inside of the damper cylinder 21 and divides the inside of the damper cylinder 21 into a piston side oil chamber 43A in which the piston rod 29 is not accommodated and a rod side oil chamber 43B in which the piston rod 29 is accommodated. The piston 42 includes an expansion side valve 44A, and includes an expansion side flow path 44 that enables communication between the piston side oil chamber 43A and the rod side oil chamber 43B, and a pressure side valve (check valve) 45A, and includes a piston side oil chamber 43A. And a pressure-side flow path 45 (not shown) that enables the rod-side oil chamber 43B to communicate with each other. Note that the oil lock piece 80 described above is screwed and fixed to the tip of the piston holder 41.

  Further, the piston valve device 40 has a damping force adjusting rod 47 which is inserted into the adjuster 28 through an O-ring 46A in a liquid-tight manner and is screwed to the damping force adjusting adjuster 46 which can be operated from the outside. The passage area of the bypass passage 48 between the piston-side oil chamber 43A and the rod-side oil chamber 43B provided in the piston holder 41 is adjusted by the needle 47A at the tip of the damping force adjusting rod 47 through the hollow portion of the rod 29. Make it possible.

  Therefore, when the front fork 10 is compressed, the oil in the piston-side oil chamber 43A passes through the pressure-side flow path 45, opens the pressure-side valve 45A, and is guided to the rod-side oil chamber 43B.

  Further, when the front fork 10 is extended, when the relative speed between the damper cylinder 21 and the piston rod 29 is low, the oil in the rod side oil chamber 43B is guided to the piston side oil chamber 43A through the bypass passage 48 having the needle 47A. In the meantime, the expansion side damping force is generated by the diaphragm resistance by the needle 47A. The damping force is adjusted by adjusting the position of the needle 47A by the damping force adjustment adjuster 46.

  Further, when the front fork 10 is extended and the relative speed between the damper cylinder 21 and the piston rod 29 is medium to high, the oil in the rod side oil chamber 43B passes through the extension side passage 44 to bend and deform the extension side valve 44A. It is guided to the piston side oil chamber 43A and generates an extension side damping force.

(Bottom valve device 50)
The bottom valve device 50 includes a bottom piece 51 inserted into a bottom valve hole 60 that is drilled from a lateral direction with respect to the central axis of the axle bracket 20 orthogonal to the axle hole 20A of the axle bracket 20 so that the bottom valve hole 60 faces sideways. The flange 51A of the bottom piece 51 is fixed to the axle bracket 20 by a cap 58 screwed into the opening. The bottom valve device 50 holds a pressure side valve 56 </ b> A, a valve housing 53, and a valve stopper 54 formed by laminating a plurality of plate valves with bolts 52 on the bottom piece 51. The valve stopper 54 holds an extension side valve (check valve) 57A and a spring 57B between the valve housing 53 and the valve stopper 53. The valve housing 53 is fluid-tightly fitted to an intermediate portion of the bottom valve hole 60 provided in the axle bracket 20 and partitions the first bottom valve chamber 60A and the second bottom valve chamber 60B. The first bottom valve chamber 60 </ b> A communicates with the piston-side oil chamber 43 </ b> A via a first communication hole 61 </ b> A (oil passage) provided in the axle bracket 20 and a central hole 22 </ b> A of the bottom plate 22. The second bottom valve chamber 60 </ b> B communicates with the oil reservoir chamber 35 </ b> A via a second communication hole 61 </ b> B (oil passage) provided in the axle bracket 20 and a small hole 22 </ b> B of the bottom plate 22. The valve housing 53 is provided with a pressure side valve 56A so as to allow communication between the first bottom valve chamber 60A and the second bottom valve chamber 60B, and an extension side valve 57A. The valve housing 53 includes the first bottom valve chamber 60A and the first bottom valve chamber 60A. An extension side flow channel 57 (not shown) that enables communication between the two bottom valve chambers 60B is provided. Accordingly, the piston-side oil chamber 43 </ b> A inside the damper cylinder 21 and the oil reservoir chamber 35 </ b> A outside the damper cylinder 21 are communicated with each other via the flow paths 56 and 57 of the bottom valve device 50.

  The bottom valve device 50 bypasses the pressure side flow path 56 and the expansion side flow path 57 to the bottom piece 51 and the bolt 52, and in other words, the first bottom valve chamber 60A and the second bottom valve chamber 60B, in other words, the piston side oil chamber 43A. And a bypass channel 59 that enables communication between the oil reservoir 35A and the oil reservoir 35A. Then, the damping force adjusting rod 62 is inserted in a liquid-tight manner through the O-ring 63 on the central axis of the cap 58 screwed to the axle bracket 20 and the tip needle 62A of the damping force adjusting rod 62 is placed at the bottom. The piece 51 and the bolt 52 are inserted into the bypass passage 59. The base end operating portion 62B of the damping force adjusting rod 62 is disposed at a position facing outward on the end face of the cap 58 that is screwed into the lateral opening of the bottom valve hole 60 avoiding the axle hole 20A of the axle bracket 20. The needle 62A is advanced and retracted by screwing the damping force adjusting rod 62 to the bottom piece 51, so that the flow path area of the needle 62A can be adjusted.

  Accordingly, when the front fork 10 is compressed, the oil corresponding to the volume of the piston rod 29 that has entered the damper cylinder 21 passes from the piston-side oil chamber 43A through the bypass channel 59 to the oil reservoir 35A or the pressure-side channel 56. And is discharged to the oil reservoir 35A. At this time, when the relative speed between the damper cylinder 21 and the piston rod 29 is low, a compression-side damping force is obtained by the throttling resistance of the needle 62A provided in the bypass passage 59. This damping force is adjusted by adjusting the position of the needle 62 </ b> A by the operation portion 62 </ b> B of the damping force adjusting rod 62. Further, when the relative speed between the damper cylinder 21 and the piston rod 29 is medium to high, the oil passing from the piston-side oil chamber 43A through the pressure-side flow path 56 bends and deforms the pressure-side valve 56A to generate a pressure-side damping force.

  When the front fork 10 is extended, the oil corresponding to the retraction volume of the piston rod 29 retreating from the damper cylinder 21 is recirculated from the oil reservoir chamber 35A to the piston-side oil chamber 43A through the expansion side flow passage 57.

Accordingly, the front fork 10 performs a damping action as follows.
(When compressed)
When the front fork 10 is compressed, in the bottom valve device 50, the pressure side damping force is generated by the oil flowing through the pressure side valve 56A or the needle 62A of the valve housing 53, and the piston valve device 40 generates almost no damping force.

(When stretched)
When the front fork 10 is extended, in the piston valve device 40, an extension side damping force is generated by the oil flowing through the needle 47A of the piston 42 or the extension side valve 44A, and the bottom valve device 50 hardly generates a damping force.

  The damping force on the compression side and the extension side suppresses the stretching vibration of the front fork 10.

  However, in the front fork 10, the oil lock collar 70 is provided on the bottom side of the damper cylinder 21, the oil lock piece 80 is provided on the tip side of the piston rod 29, and the oil lock piece 70 is attached to the oil lock collar 70 in the most compression stroke. The oil lock collar 70 and its mounting structure are configured as follows (FIG. 5) when 80 is fitted to achieve a buffering action at the time of maximum compression.

  The oil lock collar 70 has a bottomed cylindrical shape, and includes a flat bottom portion 71 and an opening 72 that expands outward. A mounting hole 73 provided at the center of the bottom 71 of the oil lock collar 70 is provided with a shaft portion 74A (coaxial with the piston rod 29) of a support shaft 74 with a head provided at the center of the bottom plate 22 constituting the bottom of the damper cylinder 21. The damper cylinder 21 is loosely fitted (floating state) so as to be freely displaceable (floating state). As a result, the center axis of the oil lock collar 70 can swing with respect to the damper cylinder 21, and the bottom 71 of the oil lock collar 70 is seated on the bottom plate 22 of the damper cylinder 21 and separated (FIG. 5). Can be switched freely. The support shaft 74 is riveted to the bottom plate 22 and includes a shaft portion 74A and a head portion 74B.

  The mounting hole 73 in the bottom 71 of the oil lock collar 70 includes a hole 73A having a smaller diameter than the head 74B of the support shaft 74, and a notch 73B extending outward from the head 74B of the support shaft 74. Provided at a plurality of positions in the circumferential direction (in this embodiment, four positions having an interval of 90 degrees). When the bottom 71 of the oil lock collar 70 is seated on the bottom plate 22 of the damper cylinder 21, the hole 73 </ b> A and the cutout 73 </ b> B of the mounting hole 73 are closed, and the bottom 71 of the oil lock collar 70 is separated from the bottom plate 22 of the damper cylinder 21. When doing so, the notch 73B of the mounting hole 73 is opened.

  At a plurality of positions in the circumferential direction of the outer periphery of the opening 72 of the oil lock collar 70 (three positions at intervals of 120 degrees in the present embodiment), claw portions 72A that protrude toward the inner peripheral side of the damper cylinder 21 are provided. Each claw portion 72 </ b> A of the oil lock collar 70 can contact and separate from the inner periphery of the damper cylinder 21, and the center axis of the oil lock collar 70 is arranged approximately near the center axis of the damper cylinder 21.

  Therefore, in the front fork 10, in the oil lock state in which the oil lock piece 80 is fitted to the oil lock collar 70 in the compression stroke, the oil lock collar 70 is pressed against the oil lock piece 80, and the oil lock collar 70 The bottom 71 is seated on the bottom plate 22 of the damper cylinder 21 to close the hole 73A and the cutout 73B of the mounting hole 73, thereby forming an oil lock chamber inside the oil lock collar 70. As a result, the oil trapped in the oil lock chamber flows out into the upper piston-side oil chamber 43A through the clearance channel on the outer periphery of the oil lock piece 80 and the inner periphery of the oil lock collar 70, and the resistance of the clearance channel An oil lock load based on

  When shifting from the oil lock state to the extension stroke, the oil lock piece 80 pulls up the oil lock collar 70 due to the presence of negative pressure in the oil lock chamber, and the bottom 71 of the oil lock collar 70 is separated from the bottom plate 22 of the damper cylinder 21. The notch 73B of the mounting hole 73 is opened. The oil in the piston side oil chamber 43A passes through the outer periphery of the oil lock collar 70 and flows into the oil lock chamber from the notch 73B of the mounting hole 73, and the negative pressure portion is eliminated. The oil lock piece 80 can be smoothly removed from the oil lock collar 70.

According to the present embodiment, the following operational effects can be obtained.
(a) Since the bottom valve device 50 is provided on the axle bracket 20, only the oil lock collar 70 is provided inside the damper cylinder 21, and it is not necessary to provide the bottom valve device 50. Therefore, the axial length of the damper cylinder 21 is shortened, and the front fork 10 can be downsized.

  (b) Since the bottom valve device 50 is provided on the axle bracket 20, the damping characteristics of the bottom valve device 50 can be easily changed without disassembling the front fork 10 and taking out the damper cylinder 21 (the number of plate valves, the plate thickness). Etc.)

  (c) Since the bottom valve device 50 is provided on the axle bracket 20, the bottom valve device 50 includes the damping force adjustment rod 62, and the operation portion 62 </ b> B of the damping force adjustment rod 62 is disposed at a position avoiding the axle hole of the axle bracket 20. Easier to do.

  (d) Since the bottom valve device 50 is provided on the axle bracket 20, it is not necessary to provide the bottom valve device 50 inside the damper cylinder 21, and the bottom plate 22 can be easily welded to the lower end of the damper cylinder 21. The bottom plate 22 is firmly coupled to the damper cylinder 21 as compared with the case where the bottom plate 22 is swaged and attached to the lower end of the damper cylinder 21 or the lower end of the damper cylinder 21 is expanded to provide a bowl-shaped portion that replaces the bottom plate 22. Can be sandwiched between the axle bracket 20 and the lower end of the inner tube 12, and the tensile strength of the front fork 10 can be improved.

  (e) When the oil lock collar 70 is provided at the bottom of the damper cylinder 21, the central axis of the oil lock collar 70 is made swingable, so that the oil lock piece 80 can be easily aligned when entering the oil lock collar 70. .

  (f) Since the plurality of claw portions 72A provided on the outer periphery of the opening 72 of the oil lock collar 70 protrude toward the inner periphery of the damper cylinder 21, the swingable oil lock of the above-described (e). The collar 70 can be disposed approximately near the center axis of the damper cylinder 21. Further, on the outer periphery of the oil lock collar 70, between the adjacent claw portions 72A and the claw portions 72A, an oil flow path is formed for eliminating the negative pressure inside the oil lock collar 70.

  (g) When the oil lock piece 80 enters the oil lock collar 70 in the most compression stroke of the front fork 10, the oil lock collar 70 is pressed by the oil lock piece 80 and is seated on the bottom of the damper cylinder 21, The hole 73A and the cutout 73B of the mounting hole 73 are closed to enable oil lock. At the time of reversal from the most compressed state to the extension stroke, the oil lock collar 70 is separated from the bottom of the damper cylinder 21 following the withdrawal of the oil lock piece 80 due to the negative pressure between the oil lock piece 80 and its mounting hole. 73, because the oil on the outer periphery of the oil lock collar 70 is introduced into the oil lock collar 70 through the notch 73B, the negative pressure is released, and the oil lock piece 80 is allowed to move out. Enables a smooth reversal to the extension stroke.

  Further, in the front fork 10, the lower end portion of the damper cylinder 21 is erected on the lower end side of the inner tube 12, an oil reservoir chamber 35 </ b> A between the inner tube 12 and the damper cylinder 21, and an oil chamber inside the damper cylinder 21. A first connecting hole 61A and a second connecting hole 61B as oil passages connecting 43A are provided in the axle bracket 20 as the lower end portion of the inner tube 12, and a bottom valve device is provided between the first connecting hole 61A and the second connecting hole 61B. When providing 50 (damping force generating portion), the following structure is provided in order to secure the tubes on the bottom surface of the axle bracket 20 and the bottom surface of the bottom plate 22 which is the lower end portion of the damper cylinder 21 (FIGS. 6 and 7).

  6, the bottom plate 22 of the damper cylinder 21 is made of a material harder than the axle bracket 20. In this embodiment, the bottom plate 22 is made of iron, the axle bracket 20 is made of aluminum, and the annular protrusion 101 is formed on the lower surface of the bottom plate 22 of the damper cylinder 21. It is provided. Then, the axle bracket 20 is screwed to the inner tube 12 as described above, and the bottom plate 22 of the damper cylinder 21 is sandwiched between the inner tube 12 and the axle bracket 20, so that the bottom plate of the damper cylinder 21 is attached to the bottom surface of the axle bracket 20. The lower surface of 22 is fastened, and the protrusion 101 is completely bited into the bottom surface of the axle bracket 20 so that the bottom surface of the axle bracket 20 and the lower surface of the bottom plate 22 of the damper cylinder 21 are brought into close contact with each other. At this time, the first communication hole 61A extending from the oil chamber 43A inside the damper cylinder 21 to the bottom valve device 50 is disposed inside the annular protrusion 101, and the second communication hole extending from the oil reservoir chamber 35A to the bottom valve device 50 is disposed. The hole 61B is disposed outside the annular protrusion 101.

  In the structural example of FIG. 7, the bottom plate 22 of the damper cylinder 21 is made of a material harder than the axle bracket 20. In this embodiment, the bottom plate 22 is made of iron, the axle bracket 20 is made of aluminum, and an annular protrusion 102 is provided on the bottom surface of the axle bracket 20. It is. Then, the axle bracket 20 is screwed to the inner tube 12 as described above, and the bottom plate 22 of the damper cylinder 21 is fastened between the inner tube 12 and the axle bracket 20, so that the bottom plate of the damper cylinder 21 is attached to the bottom surface of the axle bracket 20. The bottom surface of the damper bracket 21 is fastened, and the protrusion 102 is completely crushed by the bottom plate 22 of the damper cylinder 21 so that the bottom surface of the axle bracket 20 and the bottom surface of the bottom plate 22 of the damper cylinder 21 are in close contact. At this time, the first communication hole 61A extending from the oil chamber 43A inside the damper cylinder 21 to the bottom valve device 50 is disposed inside the annular projection 102, and the second communication hole extending from the oil reservoir chamber 35A to the bottom valve device 50 is disposed. The hole 61B is disposed outside the annular protrusion 102.

According to the present embodiment, the following operational effects can be obtained.
(a) The annular protrusion 101 (or 102) provided on one of the bottom surface on the lower end side of the inner tube 12 and the lower surface of the lower end portion of the damper cylinder 21 is completely bited into the other or is crushed to By bringing the lower surfaces into close contact with each other, it is possible to ensure the sealing of the bottom surface and the lower surface. At this time, the first communication hole 61A extending from the oil chamber 43A inside the damper cylinder 21 to the bottom valve device 50 is disposed inside the annular protrusion 101 (or 102), and extends from the oil reservoir chamber 35A to the bottom valve device 50. Since the second communication hole 61B is arranged outside the annular protrusion 101 (or 102), the communication holes 61A and 61B do not bypass the bottom valve device 50 and short-circuit, and the damping force of the bottom valve device 50 is increased. Can be stabilized.

  (b) It is not necessary to interpose an O-ring between the bottom surface on the lower end side of the inner tube 12 and the lower surface of the lower end portion of the damper cylinder 21, and the groove processing and assembly man-hours for the O-ring are not required. Can be reduced.

  (c) The annular projections 101 (or 102) provided on one of the bottom surface on the lower end side of the inner tube 12 and the lower surface of the lower end portion of the damper cylinder 21 are completely bited into or crushed by the other, Make sure that the bottom and bottom surfaces of the top and bottom are in close contact. Therefore, the degree of biting or crushing of the annular protrusion 101 (or 102) does not progress with time, and the adhesion between the bottom surface on the lower end side of the inner tube 12 and the lower surface of the lower end portion of the damper cylinder 21 becomes unstable. There is nothing. There is no possibility that the inner tube 12 and the axle bracket 20 are loosely screwed.

  (d) The axle bracket 20 is screwed to the inner tube 12, the lower end portion of the inner tube 12 is configured by the axle bracket 20, and the lower end portion of the damper cylinder 21 is sandwiched between the inner tube 12 and the axle bracket 20. Thus, the lower surface of the lower end portion of the damper cylinder 21 is fastened to the bottom surface of the axle bracket 20, and the annular protrusion 101 (or 102) provided on one of the bottom surface on the lower end side of the inner tube 12 and the lower surface of the lower end portion of the damper cylinder 21 is provided. The other of them can be completely bitten or crushed to ensure that their bottom and bottom surfaces are in close contact.

  (e) The bottom plate 22 is welded to the damper cylinder 21, and the bottom plate 22 constitutes the lower end portion of the damper cylinder 21, so that the bottom plate 22, which is the lower end portion of the damper cylinder 21, is securely located between the inner tube 12 and the axle bracket 20. Can be fastened.

  (f) The bottom plate 22 of the damper cylinder 21 is made of a material harder than the axle bracket 20. Accordingly, when the annular protrusion 101 (or 102) is provided on the lower surface of the bottom plate 22 (hard), the hard annular protrusion 101 (or 102) can be bitten into the bottom surface of the soft axle bracket 20. When the annular protrusion 101 (or 102) is provided on the bottom surface of the axle bracket 20 (soft), the soft annular protrusion 101 (or 102) can be crushed by the flat surface of the hard bottom plate 22. In either case, the bottom surface of the axle bracket 20 and the bottom plate can be completely adhered.

  Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration of the present invention is not limited to these embodiments, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention. For example, in the present invention, the height of the lower end portion of the damper cylinder (the bottom plate 22 in this embodiment) and the height of the axle bracket 20 may be different. The bottom plate 22 is made of aluminum and the axle bracket 20 is made of iron. May be made of a material softer than the axle bracket 20.

  Further, in the present invention, the structure in which the lower end portion of the damper cylinder stands on the lower end side of the axle side tube is formed by screwing the bottom bolt inserted from the outside into the lower portion of the axle side tube to the lower end portion of the damper cylinder. The bottom surface of the lower end portion of the damper cylinder may be fastened to the bottom surface on the lower end side of the axle side tube.

FIG. 1 is a sectional view showing a front fork. 2 is an enlarged cross-sectional view of the lower portion of the front fork of FIG. FIG. 3 is an enlarged cross-sectional view of an intermediate portion of the front fork of FIG. 4 is an enlarged cross-sectional view of the upper portion of the front fork of FIG. FIG. 5 is a cross-sectional view showing a damping force generator provided on the axle bracket and an oil lock collar provided on the damper cylinder. FIG. 6 is a cross-sectional view showing a structural example in which an annular projection is provided on the bottom plate of the damper cylinder. FIG. 7 is a cross-sectional view showing a structural example in which an annular protrusion is provided on the bottom surface of the axle bracket.

Explanation of symbols

10 Front fork 12 Inner tube (axle side tube)
20 Axle bracket 21 Damper cylinder 22 Bottom plate 35A Oil reservoir chamber 43A Oil chamber 50 Bottom valve device (damping force generator)
61A 1st communication hole (oil passage)
61B Second communication hole (oil passage)
101, 102 annular projection

Claims (4)

Standing the lower end of the damper cylinder on the lower end side of the axle side tube, providing an oil passage connecting the oil reservoir between the axle side tube and the damper cylinder and the oil chamber inside the damper cylinder at the lower end of the axle side tube, In the front fork in which a damping force generating part is provided in the middle part of the oil passage,
An annular projection is provided on one of the bottom surface on the lower end side of the axle side tube and the lower surface of the lower end portion of the damper cylinder, the lower surface of the lower end portion of the damper cylinder is fastened to the bottom surface on the lower end side of the axle side tube, and the projection is connected to the axle side tube. The bottom surface of the lower end side of the damper cylinder and the lower surface of the lower end of the damper cylinder are completely bited into or crushed to bring the bottom surface and the lower surface into close contact with each other,
An oil passage extending from the oil chamber inside the damper cylinder to the damping force generating portion is disposed inside the annular protrusion, and an oil passage extending from the oil reservoir chamber to the damping force generating portion is disposed outside the annular protrusion. Front fork.   The axle bracket is screwed onto the axle tube, the lower end of the axle tube is configured by the axle bracket, and the lower end of the damper cylinder is sandwiched between the axle tube and the axle bracket, thereby The front fork according to claim 1, wherein the lower surface of the lower end portion of the damper cylinder is fastened to the front fork.   The front fork according to claim 2, wherein a bottom plate is welded to the damper cylinder, and the bottom plate forms a lower end portion of the damper cylinder.   The front fork according to claim 3, wherein the bottom plate of the damper cylinder is made of a material harder than the axle bracket.

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