JP2005054943A - Front fork of motorcycle or the like - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a front fork capable of preventing an increase of the cost even when a hollow pipe is separately provided by providing the hollow pipe consisting of a hollow pipe body and a synthetic resin piston body. <P>SOLUTION: In a front fork 10 of a motorcycle or the like in which an inner tube 14 on a motorcycle body side is slidably fitted in an outer tube 11 on a wheel side, a hollow pipe 20 is erected from a bottom part of the outer tube 11, a piston body 50 which is slidably brought into contact with an inner circumference of the inner tube 14 via a piston ring 60 is provided in the hollow pipe 20, and a suspension spring 29 is supported by an upper face of the piston body 50 provided in the hollow pipe 20, the hollow pipe 20 comprises a hollow metal pipe body 40 attached to the bottom part of the outer tube 11 and the synthetic resin annular piston body 50 coupled with the hollow pipe body 40, and a rebound spring 32 to absorb shocks in a most expanded condition is supported by a lower face of a flange part 42 formed on an outer circumference of an upper end part of the hollow pipe body 40. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a front fork such as a motorcycle.

  As a front fork of a motorcycle or the like, as described in Patent Document 1, a vehicle body side inner tube is slidably fitted in a wheel side outer tube, and a hollow pipe is erected at the bottom of the outer tube. Some pipes are provided with a piston body slidably in contact with the inner periphery of the inner tube.

  A hollow pipe generally used in a front fork such as a two-wheeled vehicle has a piston body at the front end and an inner peripheral threaded portion at the base end formed integrally with the hollow pipe body by plastic working of a metal pipe material. However, in such a hollow pipe, when the inner tube has a large diameter, the piston body cannot be formed. Therefore, the hollow pipe main body and the piston body are separated.

The difference in diameter between the hollow pipe body and the piston body depends on the molding method, but in general, the limit of integral molding is limited to less than twice, and the hollow pipe body and piston body are separated separately. . Also, if the hollow pipe body size is increased, the piston body can be molded, but this time it becomes difficult to draw the proximal end threaded portion standing on the bottom of the outer tube, and the piston body has a large diameter. It is difficult to satisfy both the requirements and the maintenance of the dimensions of the base end thread portion.
JP 7-277262 A

  When the hollow pipe is separated into the hollow pipe main body and the piston body, the processing cost and parts cost of the piston body increase. In view of this, it is conceivable to reduce the cost by using a synthetic resin for the piston body to be separated.

  Patent Document 1 discloses a hollow pipe in which a synthetic resin piston (corresponding to a piston body) is attached to an upper portion of a straight pipe (corresponding to a hollow pipe body).

  In Patent Document 1, two bearing members are fitted on the upper and lower sides of the inner periphery of the outer tube, and a cushion member 51 that cushions an impact at the time of maximum extension between the outer periphery of the tip end portion of the inner tube and the lower bearing member 13. Is inserted to provide a buffer at the time of maximum extension.

  However, in the structure of this Patent Document 1, it is necessary to provide a gap between the outer tube inner periphery and the outer tube inner periphery by reducing the diameter of the outer periphery of the inner tube tip and fitting the cushion member 51 and the spring bearing ring 53. Complex and expensive.

  The structure of Patent Document 1 can be applied only to a front fork in which two bearing members are fitted on the upper and lower sides of the inner periphery of the outer tube. It cannot be applied to a type of front fork in which one bearing member is fitted to the outer periphery of the inner tube.

  A first problem is to provide a front fork that does not increase in cost even if the hollow pipe is separated from the hollow pipe body and the synthetic resin piston body.

  The second problem is to further reduce the cost by integrally forming the piston ring on the synthetic resin piston body.

  The third problem is to prevent kinking of the suspension spring accompanying compression of the suspension spring.

  According to the first aspect of the present invention, the inner tube on the vehicle body side is slidably fitted in the outer tube on the wheel side, and a hollow pipe is erected on the bottom of the outer tube. Metal that is attached to the bottom of the outer tube in a front fork such as a two-wheeled vehicle that has a piston body that slides through a piston ring and supports a suspension spring on the upper surface of the piston body provided on the hollow pipe A hollow pipe body made of a synthetic resin and an annular piston body made of synthetic resin coupled to the hollow pipe body, the bottom surface of the flange formed on the outer periphery of the upper end of the hollow pipe body, It supports a rebound spring that forms a buffer.

  According to a second aspect of the present invention, in the first aspect of the present invention, a base end portion of a piston ring having a larger outer diameter than the outer periphery of the piston body is integrally formed at a lower outer periphery of the annular piston body. The ring extends through a C-shaped gap along the outer periphery of the piston body, the front end of the piston ring is a free end, and between the flange of the hollow pipe body and the lower end surface of the piston body A washer for closing the lower end opening of the C-shaped gap is provided.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the annular piston body is rotatably coupled to the hollow pipe body.

(Claim 1)
a “Because a flange is formed on the outer periphery of the upper end of the metal hollow pipe body, and a rebound spring that supports the buffer at the maximum extension is supported on the lower surface of the flange,” the flange-shaped piston body is made of synthetic resin. However, the collar portion of the hollow pipe body is made of metal, and can receive a large tensile load at the maximum extension. As a result, the piston body made of synthetic resin is only subjected to the compression load of the suspension spring, and this compression load is much smaller than the tensile load at the maximum extension, and the piston body is made of synthetic resin. Will not cause any trouble. As a result, the rebound spring can be arranged in the hollow pipe, and the cost can be reduced without complicating the structure of the front fork.

(Claim 2)
b “Under the outer periphery of the annular piston body, a piston ring having a larger outer diameter than that of the piston body is formed integrally with the piston body through a C-shaped gap between the piston body and a free end. ”,“ Provided with a washer that closes the lower end opening of the C-shaped gap between the flange portion of the hollow pipe body and the lower end surface of the piston body ”
(1) The C-shaped gap formed between the piston ring and the outer periphery of the piston body opens up and down. As a result, the mold can be removed in the axial direction during molding, and the mold can be easily manufactured.
(2) The piston ring absorbs the eccentricity of the piston body in the radial direction through the C-shaped gap.
(3) Since the piston ring is integrally formed on the outer periphery of the annular piston body, the cost of the synthetic resin piston body can be further reduced.

(Claim 3)
c “The annular piston body is rotatably coupled to the hollow pipe body”, so that the annular piston body on which the suspension spring is seated can be rotated, and the kinking of the suspension spring accompanying the compression of the suspension spring is cancelled. it can.

  1 is an overall sectional view of a front fork, FIG. 2 is an enlarged sectional view of a lower part of FIG. 1, FIG. 3 is a sectional view showing a main part of a hollow pipe, and FIG. 4 is a plan view showing a piston body and a piston ring.

  The front fork 10 for a motorcycle slides an inner tube 14 attached to the vehicle body side through an upper bearing member (bush) 12 and a lower bearing member (bush) 13 on the inner periphery of an outer tube 11 attached to the wheel side. Inserted freely. Reference numeral 15 denotes an axle support.

  At this time, the upper bearing member 12 is provided on the inner periphery on the upper end side of the outer tube 11, and the lower bearing 13 is provided on the outer periphery on the lower end side of the inner tube 12. An oil seal 16 and a dust seal 17 are fitted in the upper end opening of the outer tube 11.

  The front fork 10 erects a hollow pipe 20 that is fixed to the bottom 11A of the outer tube 11 with a bolt 18, and a piston body 50 that is in sliding contact with the inner periphery of the inner tube 14 via a piston ring 60. Is provided.

  In the front fork 10, a spring seat 21, an oil lock collar 22, and a washer 23 are inserted in this order on the inner periphery on the lower end side of the inner tube 14, and these are held by a caulking portion 14A. An annular free valve 24 is seated on the tapered upper end surface of the oil lock collar 22, and a valve spring 25, which is backed up by a spring seat 21, presses the free valve 24 against the tapered upper end surface of the oil lock collar 22. 24 allows a slight gap 24 </ b> A to be formed between the outer periphery of the hollow pipe 20. The front fork 10 has a through hole 26A on the upper end side of the hollow pipe 20 and a through hole 26B on the lower end side.

  Accordingly, the front fork 10 forms an oil chamber 27A that is pressurized when extended by the hollow pipe 20, the piston body 50, the inner tube 14, and the free valve 24. The through hole 26A on the upper side of the hollow pipe 20 and the free valve 24 are formed. The gap 24A is used as an oil throttle passage for generating a damping force when extended. The front fork 10 forms an oil chamber 27B that is pressurized during compression by the hollow pipe 20, the outer tube 11, the inner tube 14, and the free valve 24, and the lower through hole 26B of the hollow pipe 20 is compressed. The oil throttle passage generates a damping force.

  The front fork 10 supports a suspension spring 29 between the upper surface of the piston body 50 provided at the upper end portion of the hollow pipe 20 and a cap 28A and a spring collar 28B provided at the upper end portion of the inner tube 14.

  The front fork 10 is charged with a working oil in an oil chamber 31 at a certain level inside the outer tube 11 and the inner tube 14, and a piston body 50 at the upper end of the hollow pipe 20, a cap 28A of the inner tube 14, a spring collar 28B, The suspension spring 29 to which a certain initial load (spring load at the maximum extension) is applied during the period is to be mounted. The oil chamber 31 extends from the inner tube 14 side to the hollow portion of the hollow pipe 20, communicates with the oil chamber 27A that is pressurized during the above-described expansion via the through hole 26A, and is pressurized when compressed. The oil chamber 27B communicates with the through hole 26B. Further, a gap between the outer tube 11 and the inner tube 14 between the upper bearing member 12 and the lower bearing member 13 is via a horizontal hole 22A provided in the oil lock collar 22 and a horizontal hole 22B provided in the inner tube 14. To communicate with the oil chamber 27B.

  The front fork 10 is located between the lower surface of the flange portion 42 provided on the outer periphery of the upper end portion of the hollow pipe 20 as described later and the above-described spring seat 21 provided at the lower end portion of the inner tube 14 at the time of maximum extension. A rebound spring 32 that serves as a buffer is supported.

  The front fork 10 sandwiches the bottom of an oil lock piece 33 having a bottomed cup shape between the lower end surface of the hollow pipe 20 fixed to the bottom 11A of the outer tube 11 with a bolt 18 and the bottom 11A. . The oil lock piece 33 is attached to the outer periphery of the hollow pipe 20, and a check valve 34 provided on the inner periphery of the lower end side of the oil lock collar 22 of the inner tube 14 descending at the time of the most compression is provided on the outer periphery of the oil lock piece 33. In the process of fitting, the oil lock chamber surrounded by the outer tube 11, the inner tube 14, and the oil lock piece 33 is closed and pressurized to provide a buffer during maximum compression. The check valve 34 is supported by the washer 23. At the start of expansion after the maximum compression, the check valve 34 is opened, the oil in the oil chamber 31 is supplied to the oil lock chamber via the through hole 26B of the hollow pipe 20, and the negative pressure in the oil lock chamber is immediately eliminated.

Accordingly, the front fork 10 operates as follows.
(1) When the wheel receives an impact caused by unevenness on the road surface, the front fork 10 expands and contracts with the expansion and contraction of the suspension spring 29 to mitigate this impact.

  (2) When the front fork 10 is extended in the above (1), the hydraulic oil in the oil chamber 27A pressurized at the time of extension flows out from the through hole 26A and the clearance 24A of the free valve 24 to generate a damping force, The extension of the suspension spring 29 after compression is suppressed, and resonance of the suspension spring 29 is prevented.

  When the front fork 10 is fully extended, the rebound spring 32 is compressed between the lower surface of the flange portion 42 of the hollow pipe 20 and the spring seat 21 of the inner tube 14 to absorb the impact of stretching.

  (3) In the above (1), when the front fork 10 is compressed, the hydraulic oil in the oil chamber 27B pressurized during the compression flows out of the through hole 26B to generate a damping force, and the compression speed of the suspension spring 29 Control.

  When the front fork 10 is compressed most, the check valve 34 of the oil lock collar 22 is fitted into the oil lock piece 33 to compress the oil lock chamber and absorb the impact with the bottom.

  However, the front fork 10 includes the hollow pipe 20, the piston body 50, and the piston ring 60 as follows.

  The hollow pipe 20 includes a metal hollow pipe body 40 attached to the bottom 11A of the outer tube 11 with the bolt 18 via the oil lock piece 33 described above, and a hollow pipe body 40 that is freely rotatable at the upper end of the hollow pipe body 40 (however, It is composed of an annular piston body 50 made of a synthetic resin which is coupled to a non-rotatable portion.

  The lower end portion of the hollow pipe main body 40 is a small diameter throttle portion 41, and a screw portion 41 </ b> A is provided on the inner diameter of the small diameter throttle portion 41. The oil lock piece 33 is fitted on the outer periphery of the lower end side of the hollow pipe body 40, and the bolt 18 inserted through the bottom portion of the oil lock piece 33 from the outer surface side of the bottom portion 11 </ b> A of the outer tube 11 is inserted into the hollow pipe body. It is screwed to 40 screw parts 41A. The bolt 18 attaches the hollow pipe body 40 to the bottom portion 11 </ b> A of the outer tube 11 in a state where the bottom portion of the oil lock piece 33 is sandwiched between the lower end surface of the hollow pipe body 40 and the bottom portion 11 </ b> A of the outer tube 11.

  The upper end portion of the hollow pipe body 40 is provided with a flange portion 42 having an enlarged diameter on the outer periphery. The piston body 50 includes an annular protrusion 52 having a small outer diameter projecting from the inner peripheral side of the lower end surface of the large outer diameter annular main body 51, and the annular protrusion 52 is formed on the inner side of the upper end side of the hollow pipe body 40. The claw 52 </ b> A provided on the outer periphery of the annular protrusion 52 is engaged with the annular recess 43 provided on the inner periphery on the upper end side of the hollow pipe body 40. As a result, the piston body 50 is coupled to the inner periphery of the hollow pipe main body 40 in a retaining state, and the lower end surface of the annular main body 51 is in contact with and supported by the upper surface of the flange 42 of the hollow pipe main body 40.

  When the above-described rebound spring 32 is supported on the lower surface of the flange portion 42 of the hollow pipe body 40 constituting the hollow pipe 20, the hollow pipe body 40 has a small diameter portion 44 </ b> A and a large diameter on the outer periphery directly below the neck portion 42 (lower neck portion). The diameter portions 44B are arranged side by side in order, and the upper end inner diameter portion of the rebound spring 32 made of a coil spring can be engaged with the lower surface of the flange portion 42 and the small diameter portion 44A sandwiched between the large diameter portions 44B. The large diameter portion 44B has a larger diameter than the inner diameter of the rebound spring 32 in the free state.

  The piston ring 60 has a generally ring shape having a larger outer diameter than the outer periphery of the annular body 51 of the piston body 50, and the base end portion 61 </ b> A is formed integrally with the lower outer periphery of the annular body 51 of the piston body 50. . The piston ring 60 extends around the annular main body 51 via a C-shaped gap 62 along the outer periphery of the annular main body 51 of the piston body 50, and makes the distal end portion 61B a free end. As shown by the broken line in FIG. 4, the piston ring 60 has an elastic diameter-expanding behavior that has a larger outer diameter than the inner peripheral diameter of the inner tube 14 in a free state.

  When the lower end surface of the annular main body 51 of the piston body 50 is supported in contact with the flange 42 of the hollow pipe main body 40 as described above, the piston is interposed between the lower end surface of the annular main body 51 and the flange 42. An inner peripheral portion of a washer 63 that closes a lower end opening of the C-shaped gap 62 of the ring 60 is provided.

According to the present embodiment, the following operational effects can be obtained.
a “A hollow portion 42 is formed on the outer periphery of the upper end portion of the metal hollow pipe main body 40, and a rebound spring 32 that cushions at the time of maximum extension is supported on the lower surface of the flange portion 42”. Although 50 is a synthetic resin, the collar part 42 of the hollow pipe main body 40 is made of metal and can receive a large tensile load at the maximum extension. As a result, only the compression load of the suspension spring 29 acts on the synthetic resin piston body 50. This compression load is much smaller than the tensile load at the maximum extension, and the piston body 50 is made of synthetic resin. But it will not cause any trouble. As a result, the rebound spring 32 can be disposed in the hollow pipe 20, and the cost can be reduced without complicating the structure of the front fork 10.

b “A piston ring 60 having a distal end side as a free end and a larger outer diameter than the piston body 50 via a C-shaped gap 62 between the piston body 50 and a lower outer periphery of the annular piston body 50. , And “a washer 63 for closing the lower end opening of the C-shaped gap 62 is provided between the flange 42 of the hollow pipe body 40 and the lower end surface of the piston body 50”.
(1) A C-shaped gap 62 formed between the piston ring 60 and the outer periphery of the piston body 50 opens vertically. As a result, the mold can be removed in the axial direction during molding, and the mold can be easily manufactured.
(2) The piston ring 60 absorbs the eccentricity of the piston body 50 in the radial direction by the C-shaped gap 62.
(3) Since the piston ring 60 is integrally formed on the outer periphery of the annular piston body 50, the cost of the synthetic resin-made piston body 50 can be further reduced.

  c. “The annular piston body 50 is rotatably coupled to the hollow pipe body 40”, so that the annular piston body 50 on which the suspension spring 29 is seated is rotatable, and the suspension associated with the compression of the suspension spring 29 is suspended. The kinking of the spring 29 can be canceled.

  The embodiment of the present invention has been described with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention, Included in the invention. For example, the piston ring provided on the outer periphery of the annular piston body may be provided separately from the piston body and fitted in the outer peripheral groove of the piston body.

FIG. 1 is an overall cross-sectional view of the front fork. 2 is an enlarged cross-sectional view of the lower part of FIG. FIG. 3 is a cross-sectional view showing the main part of the hollow pipe. FIG. 4 is a plan view showing the piston body and the piston ring.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Front fork 11 Outer tube 14 Inner tube 20 Hollow pipe 29 Suspension spring 32 Rebound spring 40 Hollow pipe main body 42 Grow part 50 Piston body 60 Pistring 62 C-shaped clearance 63 Washer

Claims (3)

The inner tube on the vehicle body side is slidably fitted in the outer tube on the wheel side, and a hollow pipe is erected on the bottom of the outer tube, and the hollow pipe is slidably contacted with the inner periphery of the inner tube via a piston ring. A piston body,
In a front fork such as a motorcycle that supports a suspension spring on the upper surface of a piston body provided in a hollow pipe,
The hollow pipe is composed of a metal hollow pipe body attached to the bottom of the outer tube, and a synthetic resin annular piston body coupled to the hollow pipe body,
A front fork for a two-wheeled vehicle or the like, characterized in that a rebound spring that supports a buffer at the time of maximum extension is supported on a lower surface of a flange portion formed on an outer periphery of an upper end portion of a hollow pipe body. A base end portion of a piston ring having a larger outer diameter than the outer periphery of the piston body is formed integrally with a lower outer periphery of the annular piston body, and a C-shaped gap is formed along the outer periphery of the piston body. Extending through the piston ring, the free end of the piston ring,
The front fork of a motorcycle or the like according to claim 1, wherein a washer for closing a lower end opening of the C-shaped gap is provided between a flange portion of the hollow pipe main body and a lower end surface of the piston body. The front fork of a motorcycle or the like according to claim 1 or 2, wherein the annular piston body is rotatably coupled to the hollow pipe body.

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