JP2012002283A - Fluid pressure shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relate to a fluid pressure shock absorber and to improvement of a structure capable of stopping vibration of a cylinder when attaching the cylinder configuring a damper to a bottom member.SOLUTION: In a fluid pressure shock absorber in which a bottom member 20 comprises an opening side large opening 20a formed on the side of a shock absorber body and a backside small opening 20b formed on the backside, a bottom part of an inner tube 2 is joined to an inner circumference of the opening side large opening 20a, and then a bottom part of a cylinder 31 is inserted into the backside small opening 20b to sandwich the cylinder 31 by a head member 30 fixed on a joining means J to be joined to the inner tube 2 and the bottom member 20, and thereby, the inner tube 2 and the cylinder 31 are fixed on the bottom member 20, there is provided a partition wall member 7 that defines an air chamber A between the cylinder 31 and the inner tube 2 and the partition wall member 7 is so accommodated within the inner tube 2 as to guide the bottom part of the cylinder 31 into the backside small opening 20b.

Description

  The present invention relates to a fluid pressure shock absorber, and more particularly, to an improved structure for guiding a cylinder into a small opening on the back side of a bottom member while preventing a cylinder from swinging.

  Various proposals have been made for fluid pressure shock absorbers so far. For example, the fluid pressure shock absorber is used as a suspension device such as a front fork or a rear cushion unit that suspends a wheel of a two-wheeled vehicle and attenuates road surface vibration input to the wheel. The

  Patent Document 1 discloses a configuration of a conventional front fork. The front fork includes a fork body including an outer tube and an inner tube that is slidably inserted into the outer tube, and is inverted. Set to type.

  The fork main body is provided with a cap member for sealing the upper and lower openings and a bottom member, and the fork main body accommodates an upright damper that generates a predetermined damping force therein. A reservoir chamber for storing the working fluid is formed between the damper and the damper.

  The damper includes a cylinder that stands up at the axial center of the inner tube and accommodates a working fluid, a rod that is fixed to the outer tube and protrudes and retracts into the cylinder, and is held at the tip of the rod to move inside the cylinder. A piston partitioning into two working chambers.

  As disclosed in FIGS. 3 and 4 of Patent Document 1, a head member and a base member are respectively screwed into the head portion and the bottom portion of the cylinder.

  By the way, the bottom member that seals the lower opening of the fork main body is formed in a cylindrical shape, and an opening-side large opening that forms a large-diameter columnar space on the fork main body side, and the cylindrical space A rear-side small opening that forms a small-diameter cylindrical space extending coaxially.

  And by providing the said structure, the bottom part of an inner tube is screwed together in the said opening side large opening inner periphery, Then, the said base member is inserted in the said back side small opening part, and the said base member outer periphery and a back side A space between the inner periphery of the small opening is sealed with a seal member.

  Next, by screwing the bottom portion of the cylinder into the base member, the cylinder can be fixed to the axial center portion of the inner tube.

  In the front fork of Patent Document 1, it is necessary to thread the opening on the head side and the bottom side of the cylinder. For this threading, at least the thickness of the opening is increased and threading is performed. It is necessary to prevent the mechanical strength from being lowered, which obstructs the weight reduction of the front fork, and requires labor for processing.

  Therefore, the applicant has created the following front fork as a fluid pressure shock absorber in order to reduce the weight and improve the workability without the need for threading the cylinder.

  As shown in FIG. 3, the front fork has the same basic structure as the front fork of Patent Document 1, and the bottom member 20 is formed in a bottomed cylindrical shape, and the inner periphery and the rear side of the opening-side large opening 20a. A guide washer W1 is disposed on a step portion 20c formed at the boundary with the inner periphery of the small opening 20b.

  Then, the bottom portion (lower side in the figure) of the inner tube 2 is screwed into the inner periphery of the opening-side large opening portion 20a, and the guide washer W1 is sandwiched between the bottom end of the inner tube 2 and the step portion 20c. To do.

  Next, the bottom part (lower side in the figure) of the cylinder 31 is inserted into the back side small opening 20b, and the head part (upper side in the figure) of the cylinder 31 and the inner tube 2 are joined via the joining means J.

  The conventional front fork is provided with the guide washer W1, so that when the cylinder 31 is inserted into the back side small opening 20b, the bottom fork is guided to the back side small opening 20b while keeping the bottom of the cylinder 31 steady. It becomes possible to do.

  Further, since the front fork has the above-described configuration, the cylinder 31 can be fixed to the bottom member 20 without screwing the cylinder 31.

JP 2008-69830 A

  The conventional fluid pressure shock absorber as the front fork is useful in that it is possible to reduce the weight and improve the workability of the fluid pressure shock absorber without the need for cylinder threading.

  However, there is a demand for further weight reduction of the fluid pressure shock absorber, and an object of the present invention is to provide a fluid pressure shock absorber capable of further weight reduction.

  Means for solving the above problems are a shock absorber body comprising an outer tube and an inner tube slidably inserted into the outer tube, and a bottom for sealing the bottom side opening of the shock absorber body. A damper that is housed in the shock absorber body and generates a predetermined damping force, and the damper is provided with a cylinder that stands up at the axial center of the inner tube and accommodates the working fluid therein. The bottom member is formed on the shock absorber body side to form a large-diameter cylindrical space at the axial center, and a small-diameter cylindrical space is formed coaxially on the back side of the cylindrical space. A bottom opening of the inner tube is coupled to the inner periphery of the opening large opening, and then the bottom portion of the cylinder is inserted into the inner small opening to the inner tube. In the fluid pressure shock absorber that fixes the inner tube and the cylinder to the bottom member by sandwiching the cylinder between the head member fixed to the coupling means to be combined and the bottom member, the cylinder and the inner tube And a partition member that defines an air chamber, and the partition member is accommodated in the inner tube and guides the bottom portion of the cylinder into the back side small opening.

  According to the present invention, the partition member serves as a conventional guide washer, and an air chamber can be defined by the partition member, and the hydraulic fluid stored in the shock absorber body is reduced to reduce the fluid pressure shock absorber. Can be reduced in weight.

It is a half section view showing the most contracted state of the front fork which is a fluid pressure shock absorber according to an embodiment of the present invention. It is a perspective view which expands and shows the partition member in the front fork which is a fluid pressure buffer which concerns on one embodiment of this invention. It is a longitudinal cross-sectional view which shows the front fork which is the conventional fluid pressure buffer partially.

  A fluid pressure shock absorber according to an embodiment of the present invention will be described below with reference to the drawings. The same reference numerals given throughout the several drawings indicate the same or corresponding parts.

  The fluid pressure shock absorber according to the present embodiment is a front fork that suspends a front wheel of a motorcycle and attenuates road surface vibration input to the front wheel due to unevenness of the road surface.

  Although not shown, the front fork is composed of a pair of left and right fork members whose upper end portions are connected by a bridge mechanism, and the lower ends of the fork members are connected to the axles of the front wheels and suspended so as to sandwich the front wheels.

  Further, although not shown, the bridge mechanism has a steering shaft coupled to a handle, and the front mechanism can be steered by operating the handle by including the configuration.

  As shown in FIG. 1, the fork member includes a fork main body that is a shock absorber body including an outer tube 1 and an inner tube 2 that is slidably inserted into the outer tube 1, and a bottom side of the fork main body. (Lower side in the figure) comprises a bottom member 20 that seals the opening, and a damper 3 that is housed in the fork body and generates a predetermined damping force.

  The damper 3 includes a cylinder 31 that stands up at the axial center of the inner tube 2 and accommodates a working fluid therein, and the bottom member 20 is formed on the fork main body side and has a large-diameter circle at the axial center. An opening-side large opening 20a that forms a columnar space, and a back-side small opening 20b that coaxially forms a small-diameter columnar space on the back side of the columnar space are provided.

  And the bottom part of the said inner tube 2 is couple | bonded with the inner periphery of the said opening side large opening part 20a, Then, the bottom part of the said cylinder 31 is penetrated in the said back side small opening part 20b, and it couple | bonds with the said inner tube 2 The cylinder 31 is held between the head member 30 fixed to the coupling means J and the bottom member 20.

  As a result, the front fork fixes the inner tube 2 and the cylinder 31 to the bottom member 20.

  The front fork includes a partition member 7 that defines an air chamber A between the cylinder 31 and the inner tube 2, and the partition member 7 is accommodated in the inner tube 2 so that the bottom portion of the cylinder 31 is provided. Is guided into the back side small opening 20b.

  Hereinafter, each component of the front fork will be described in detail.

  The fork main body composed of the outer tube 1 and the inner tube 2 constitutes an inverted front fork in which the outer tube 1 is disposed on the vehicle body side and the inner tube 2 is disposed on the wheel side.

  The fork main body has its upper and lower ends sealed with a cap member 10 and a bottom member 20, respectively, and includes a suspension spring S that absorbs road surface vibration and a damper 3 that generates a predetermined damping force. Contain.

  By providing the above configuration, the front fork can attenuate the expansion and contraction motion accompanying the absorption of road surface vibration by the suspension spring S by the damper 3, and the riding comfort of the two-wheeled vehicle can be improved.

  The bottom member 20 is formed in a bottomed cylindrical shape, and has an opening-side large opening 20a that is screwed to the outer periphery of the inner tube 2, and a cylinder 31 of the damper 3 that is coaxially formed on the back side of the cylindrical space. Is provided with a small-diameter back side small opening 20b, and a step 20c formed between the opening side large opening 20a and the back side small opening 20b.

  A reservoir chamber R is formed between the fork main body and the damper 3, and the working fluid is stored and gas is sealed upward through the liquid level O of the working fluid to form an air chamber G. Is done.

  The liquid level O is immersed in the working fluid stored in the reservoir chamber R even when the fork main body where the liquid level O is the lowest is extended, even when the fork body 30 is in contact with the upper end in FIG. Is set.

  The air chamber G expands and contracts with the expansion and contraction of the fork main body, generates a predetermined spring reaction force, and functions as an air spring.

  Although not shown, the internal pressure of the air chamber G can be adjusted by an air valve provided in the cap member 10.

  The suspension spring S that absorbs road surface vibrations input to the front wheels includes a coil spring interposed between the cylindrical spring receiving case 11 fixed to the cap member 10 and the head member 30.

  The spring receiving case 11 is moved up and down by a turning operation of an adjuster 12 provided at the axial center of the cap member 10 to adjust the spring force of the suspension spring S.

  The damper 3 for attenuating the expansion and contraction motion of the fork main body accompanying the absorption of road surface vibrations by the suspension spring S includes a cylinder 31 standing on the axial center of the inner tube 2 and containing a working fluid, and a cap member on the outer tube 1 10 is provided with a rod 32 which is fixed via 10 and protrudes into and out of the cylinder 31 and a damping force generating means for generating a predetermined damping force as the rod 32 protrudes and retracts.

  The cylinder 31 is fixed to the bottom member 20 via a coupling means J that couples to the inner tube 2.

  Specifically, the cylinder 31 includes a head member 30 that is screwed into the coupling means J and contacts the upper end of the cylinder 31 in the drawing, and a bottom member that contacts the lower end of the cylinder 31 in the drawing via the base member 34. 20 between the two.

  The cylinder 31 has two working chambers defined by the piston 33 inside the cylinder 31 formed between the head member 30 and the base member 34, that is, an extension side action located on the rod side. The pressure side action chamber P2 located in the chamber P1 and the piston side is formed.

  The head member 30 is formed in an annular shape and is provided with an annular bush (not shown) on the inner periphery thereof. The head member 30 is in sliding contact with the outer periphery of the rod 32 to help the rod 32 smoothly appear and retract in the cylinder 31.

  The coupling means J coupled to the inner tube 2 includes a stopper member 5 that is formed in an annular shape and the head member 30 is screwed into the inner periphery, an insertion hole (not shown) that is opened in the stopper member 5, and an inner member. It consists of a pin 6 that passes through an insertion hole (not shown) opened in the tube 2 and a snap ring 60 that urges the pin 6 toward the outer periphery.

  By providing the structure, it is possible to fix the stopper member 5 with the pin 6 according to the position of the insertion hole of the inner tube 2, whereby the front fork is inserted into the inner tube 2 after the cylinder 31 is inserted. The head member 30 can be screwed into the stopper member 5 to fix the cylinder 31 to the bottom member 20.

  The configuration of the coupling means J can be selected as appropriate. For example, the stopper member 5 and the head member 30 may be fixed to the inner tube 2 by welding.

  The damping force generating means for generating a predetermined damping force in the damper 3 includes an extension side leaf valve (not shown) that generates a predetermined damping force when the fork body is extended, and a predetermined damping force when the fork body is contracted. A pressure side leaf valve (not shown) for generating

  In this embodiment, the extension side leaf valve is fixed to the piston 33 held at the tip of the rod 32, and the pressure side leaf valve is fixed to the bottom end (lower side in the figure) of the cylinder 31. Mounted on the base member 34.

  Although not shown, the piston 33 is formed with an extension side flow path and a pressure side flow path communicating with the two action chambers P1 and P2, and the pressure side action chamber P2 side which is the outlet side of the extension side flow path. The extension side leaf valve is mounted to be openable and closable.

  On the other hand, a pressure side check valve C1 is attached to the pressure side flow path so as to be freely opened and closed on the side of the expansion side working chamber P1 which is the outlet side.

  Further, although not shown in the drawing, the base member 34 is formed with an extension-side channel and a pressure-side channel that communicate the pressure-side action chamber P2 and the reservoir chamber R, and this is the outlet side of the pressure-side channel. The pressure side leaf valve is mounted on the reservoir chamber R side so as to be openable and closable.

  On the other hand, the extension side check valve C2 is attached to the extension side flow path of the base member 34 so as to be openable and closable on the pressure side action chamber P2 side which is the outlet side.

  By providing the above structure, resistance is generated when the working fluid moves by pushing open the leaf valves, so the front fork can function as a fluid pressure damper by attenuating the expansion and contraction movement of the fork body. It becomes.

  Then, when the fork main body expands and contracts, the reservoir chamber R can compensate for the excess or deficient working fluid in the cylinder 31 of the rod 32 through the base member 34.

  The configuration of the damping force generating means is not limited to the above, and a known configuration can be adopted as appropriate.

  The partition member provided on the outer periphery of the cylinder 31 is made of hard rubber, and from the substantially cylindrical boot 7 attached to the outer periphery of the cylinder 31 when the cylinder 31 is inserted into the back side small opening 20b of the bottom member 20. Become.

  As shown in FIG. 2, the boot 7 is formed between a pair of upper and lower close contact portions 70, 71 formed on the upper and lower end portions and the inner periphery being reduced in diameter, and between the close contact portions 70, 71. Is provided with a separation portion 72 which is separated from the outer periphery of the cylinder.

  A garter spring 74 is attached to the outer periphery of the pair of upper and lower close contact portions 70 and 71.

  Further, the outer periphery of the lower close-up portion 71 in the figure is expanded in diameter to form a flange 71a, and a notch 71b is formed in the outer periphery of the flange 71a along the circumferential direction.

  By providing the structure, the flow path L in which the working fluid moves is formed between the inner periphery of the washer W sandwiched between the step portion 20c of the bottom member 20 and the inner tube 2 and the notch 71b. Is possible.

  A plurality of ribs 72a are formed along the axial direction on the outer periphery of the spacing portion 72, and a flow path (not shown) through which the working fluid moves is formed between the ribs 72a and 72a.

  In addition, the configuration of the flow path of the notch 71b and the rib 72a is not limited to that illustrated, and can be selected as appropriate as long as the movement of the working fluid moving in the reservoir chamber R is not hindered. It is.

  Further, since the boot 7 includes the close contact portions 70 and 71 and the separation portion 72, an air chamber A (FIG. 1) can be defined between the inner periphery of the separation portion 72 and the outer periphery of the cylinder 31. It becomes possible.

  Therefore, the volume of the working fluid stored in the reservoir chamber R can be reduced by the air chamber A while maintaining the height of the liquid level O, and the front walk can be further reduced in weight.

  The shape and material of the partition wall member 7 are not limited to the above, but as long as the partition wall member 7 can guide the inside of the back side small opening 20b while preventing the cylinder 31 from swinging and can define the air chamber A on the outer periphery of the cylinder 31. It is possible to select the shape as appropriate.

  For example, the separation portion 72 of the boot 7 may be formed of a hard synthetic resin, and the close contact portions 70 and 71 may be formed of a soft rubber.

  In addition, by providing the garter spring 74, the inner periphery of the close contact portions 70 and 71 can be reliably brought into close contact with the outer periphery of the cylinder 31, but this is not restrictive.

  Next, a method for assembling the cylinder 31 in the front fork according to the present embodiment will be described.

  First, the washer W is disposed on the step portion 20c of the bottom member 20, the inner tube 2 is screwed into the opening side large opening portion 20a, and the washer W is sandwiched between the inner tube 2 and the step portion 20c.

  Next, the boot 7 fitted with the garter spring 74 is inserted into the inner tube 2, the coupling means J is inserted into the inner tube 2, and the insertion hole of the inner tube 2 and the insertion hole of the stopper member 5 are made to face each other. .

  Accordingly, the pin 6 passes through the insertion hole of the stopper member 5 and the insertion hole of the inner tube 2 by the urging force of the snap ring 60, and the stopper member 5 is coupled to the inner periphery of the inner tube 2.

  Then, the cylinder 31 is inverted, the base member 34 is placed on the bottom end thereof, and the cylinder 31 is inserted into the inner tube 2 so that the inner tube 2 is covered with the cylinder 31.

  At this time, by providing the boot 7, it is possible to guide the cylinder 31 into the small opening 20b on the back side of the bottom member 20 while keeping the cylinder 31 steady with the boot 7 instead of the conventional guide washer W1. .

  Further, since the flange 71a is formed on the boot 7 so that the flange 71a contacts the washer W and is prevented from moving to the bottom side, the boot 7 is pushed to the bottom end of the cylinder 31, and the base member It becomes possible to prevent the movement of the working fluid moving between the pressure side working chamber P2 and the reservoir chamber R from being hindered through 34.

  Further, in the present embodiment, since it is possible to fix the cylinder 31 to the bottom member 20 without threading, the weight of the front fork and the workability are improved as compared with Patent Document 1. It becomes possible.

  While the preferred embodiment of the present invention has been described above, it should be understood that modifications, variations and changes may be made without departing from the scope of the claims.

  For example, in the above embodiment, the present invention is embodied in the front fork. However, the present invention is not limited to this. For example, the present invention may be embodied in another fluid pressure buffer such as a rear cushion unit.

A Air chamber C1, C2 Check valve G Air chamber J Coupling means P1 Extension side action chamber P2 Pressure side action chamber R Reservoir room S Suspension spring W Washer W1 Guide washer 1 Outer tube 2 Inner tube 3 Damper 5 Stopper member 6 Pin 7 Boot ( Bulkhead member)
10 Cap member 11 Spring receiving case 20 Bottom member 20a Open side large opening 20b Back side small opening 20c Step 30 Head member 31 Cylinder 32 Rod 33 Piston 34 Base member 60 Flange 70, 71 Close part 71a Flange 71b Notch 72 Separation Part 72a rib

Claims (4)

A shock absorber body comprising an outer tube and an inner tube slidably inserted into the outer tube, a bottom member for sealing the bottom opening of the shock absorber body, and accommodated in the shock absorber body And a damper that generates a predetermined damping force,
The damper is provided with a cylinder that stands up at the axial center of the inner tube and accommodates a working fluid therein,
The bottom member is formed on the shock absorber body side to form an opening-side large opening that forms a large-diameter columnar space in the axial center, and a small-diameter columnar space is formed coaxially on the back side of the columnar space. With a back side small opening,
A head fixed to a coupling means coupled to the inner tube by coupling the bottom portion of the inner tube to the inner periphery of the large opening on the opening side, and then inserting the bottom portion of the cylinder into the small opening on the back side. In the fluid pressure shock absorber that fixes the inner tube and the cylinder to the bottom member by sandwiching the cylinder between the member and the bottom member,
A partition member defining an air chamber between the cylinder and the inner tube;
The partition member is accommodated in the inner tube in advance and guides the bottom portion of the cylinder into the back side small opening. The partition member comprises a substantially cylindrical boot that is mounted on the outer periphery of the cylinder when the cylinder is inserted into the back side small opening.
The boots are formed on the upper and lower ends, the inner circumference is reduced in diameter, and a pair of close contact portions that are in close contact with the outer periphery of the cylinder, and a separation portion that is formed between the close contact portions and in which the inner periphery is separated from the outer periphery of the cylinder The fluid pressure shock absorber according to claim 1, comprising:   3. The fluid pressure shock absorber according to claim 2, wherein a flange is formed at the one close contact portion.   The fluid pressure shock absorber according to claim 2 or 3, wherein the partition member is made of hard rubber, and a garter spring is mounted on each of the outer periphery of the pair of close portions.

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