JP2009257479A - Front fork - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a front fork with a built-in double-rod type damper that achieves position-dependent damping characteristics and impact relaxation during the maximum contraction operation. <P>SOLUTION: The front fork has a double-rod type damper at the axial center part. The dumper has a cylinder body 3 and a rod body 4. The cylinder body 3 is erected at the axial center part of a wheel-side tube 2 in the presence of a sub-cylinder body 31. The rod body 4 is suspended at the axial center part of a vehicle-body-side tube 1 while being composed of one rod body 42 and the other rod body 43. The sub-cylinder body 31 vertically has a plurality of orifices 31b that allow communication between a reservoir chamber R and the inside of the sub-cylinder body 31 while making a space in-between the wheel-side tube 2 as the reservoir chamber R. The plurality of vertically arranged orifices 31b are successively closed by a moving body 10 that synchronously descends inside the sub-cylinder body 31 during the contraction operation of a fork body. The moving body 10 advances into an oil lock case, composed of a bottom part of the sub-cylinder body 31, during the maximum contraction of the fork body. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a front fork, and more particularly, to an improvement in a front fork that is a hydraulic shock absorber that is mounted on a front wheel side of a motorcycle and absorbs road surface vibration.

  There have been various proposals for a front fork that is a hydraulic shock absorber that is mounted on the front wheel side of a motorcycle and absorbs road surface vibration. Among them, Patent Document 1 includes a double rod type damper. A front fork is disclosed.

  That is, the front fork disclosed in this document has a double rod type damper at the shaft core portion of an inverted fork main body in which a wheel side tube is inserted in a vehicle body side tube in a retractable manner under the presence of a suspension spring. .

  The damper allows the rod body suspended from the shaft core portion of the vehicle body side tube to pass through the cylinder body standing under the sub-cylinder body in the shaft core portion of the wheel side tube, and the rod body is inserted into the cylinder body. The base end of each rod body is connected to a piston body that is slidable so as to be connected to each other, and the distal end side of each rod body protrudes out of the cylinder body through the end of the cylinder body. .

  Therefore, in this double rod type damper, both the oil chambers defined by the piston body are made the same in the cylinder body, so that the generated damping force when the damper is operated in both directions can be made the same.

On the other hand, in the front fork disclosed in this document, since the damper has a check valve at the end of the cylinder body through which the rod body penetrates, hydraulic oil injected into the fork body and outside the damper is supplied to the fork body. The pumping operation can easily fill the damper.
Japanese Patent Application Laid-Open No. 2004-293660 (abstract, see paragraphs 0012 and 0013 of the specification, FIG. 1 and FIG. 3)

  However, in the front fork disclosed in the above literature, there is basically no problem with respect to facilitating filling of the hydraulic oil into the damper and making the damping force generated in the damper the same in both directions. However, it may be pointed out that a favorable attenuation characteristic cannot be obtained.

  That is, in the front fork mounted on the front wheel side of the motorcycle, it may contract with a large stroke at the time of nose dive due to sudden braking in the motorcycle or landing after jumping, from that viewpoint, It is preferable to obtain a position-dependent attenuation characteristic.

  However, the proposal to make the damper built in the front fork into a double rod type has been in recent years, and therefore, a proposal to obtain a position-dependent damping characteristic in the front fork incorporating this double rod type damper. At present, no proposal has been made to make the shock mitigation possible during the most contraction operation.

  Accordingly, the present invention has been developed in view of the above-described present situation, and the object of the present invention is to provide a position-dependent damping characteristic while incorporating a double rod type damper, and to perform the most contraction operation. It is to provide a front fork that is ideal for reducing the impact of the time and expecting to improve its versatility.

  In order to achieve the above-mentioned object, the front fork according to the present invention basically has a configuration in which the fork main body composed of the vehicle body side tube and the wheel side tube is urged in the extending direction by the suspension spring while being pushed in the axial direction. In a front fork having a double rod type damper, the damper is composed of a cylinder body and a rod body, and the cylinder body stands on the shaft core portion of the wheel side tube under the sub-cylinder body. The rod body and the other rod body are suspended from the shaft core portion of the vehicle body side tube, and the sub cylinder body communicates with the sub cylinder body while the sub cylinder body serves as a reservoir chamber between the wheel side tube. A plurality of permissible orifices are provided in the vertical direction, and the plurality of orifices in the vertical direction are synchronized within the sub cylinder when the fork body is contracted. Mobile at lowest shrinkage fork bodies while sequentially closed by moving body descends and becomes enters into the oil lock case formed from the bottom portion in the sub-cylinder body.

  Therefore, in the present invention, when the fork main body of the front fork contracts and the moving body descends in the sub-cylinder body, a plurality of moving bodies are opened in the vertical direction in the sub-cylinder body. Since the orifices that allow communication with the reservoir chamber are sequentially blocked from above, the communication between the sub-cylinder body and the reservoir chamber is cut off according to the contraction position, and the damping force is gradually increased.

  When the front fork is in the most contracted state, the moving body enters the oil lock case formed of the bottom portion of the sub cylinder body to obtain the oil lock effect, so that desired impact relaxation is realized.

  As a result, according to the present invention, in the front fork having a double rod type damper in the fore body, it is possible to realize a damping action according to the expansion / contraction position and to exhibit a predetermined oil lock effect. Ideal for expecting improved versatility.

  Hereinafter, the present invention will be described based on the illustrated embodiment. The front fork according to the present invention is a hydraulic shock absorber that is mounted on the front wheel side of a two-wheeled vehicle and absorbs road surface vibration, as shown in FIG. Further, the fork main body composed of the vehicle body side tube 1 and the wheel side tube 2 has a double rod type damper at the shaft core portion while being urged in the extending direction by the suspension spring S.

  The fork body is set upside down, and the upper end side of the wheel side tube 2 is inserted into the lower end side of the vehicle body side tube 1 so as to be able to protrude and retract. The vehicle body side tube 1 is connected to the upper bracket B1 and the under bracket B2. The bracket B1 connects the handle, and the wheel-side tube 2 suspends the front wheel at the lower end portion. Therefore, when the handle is steered, the front wheel is turned through the fork body.

  In addition, the upper end side of the wheel side tube 2 has holes 2a and 2b that allow communication between the inside and the outside as appropriate, and between the vehicle body side tube 1 and the wheel side tube 2 through the holes 2a and 2b. Inflow of oil is allowed, and lubrication between the two is guaranteed.

  The interior of the fork main body is a reservoir chamber R, and the oil level O is positioned so that a damper (described later) is in an oil-immersed state even when the fork main body is fully extended. The chamber A exhibits an air spring effect when the fork main body is extended and contracted.

  The suspension spring S accommodated in the fork main body is supported by a head portion which is an upper end portion of a cylinder body 3 which will be described later and constitutes a damper, and the upper end is the lower end of the cap member 11 which closes the upper end opening of the vehicle body side tube 1. It is latched via a spacer S1 to a holder portion 11a that connects a rod body 4 which will be described later and is a damper.

  The damper has a cylinder body 3 and a rod body 4, and the cylinder body 3 stands on the shaft core portion of the wheel side tube 2 under the sub-cylinder body 31, and the upper end portion of the rod body 4 is as described above. The cap member 11 is connected to the holder portion 11 a with the lock nut 41 interposed therebetween, and is suspended from the shaft core portion of the vehicle body side tube 1.

  The cylinder body 3 slidably houses the piston body 5, and the piston body 5 defines one chamber R1 and the other chamber R2 in the cylinder body 3, and the one chamber R1 and the other chamber R2 The body 5 can communicate with each other via the damping valves 5a and 5b, and the damping valves 5a and 5b generate a predetermined damping force when the hydraulic oil passes through.

  The rod body 4 is composed of one rod body 42 and the other rod body 43. As shown in the figure, the rod body 42 is suspended from the shaft core portion of the vehicle body side tube 1 while the base end side is a cylinder body. The other rod body 43 is protruded from the cylinder body 3 so that the other rod body 43 protrudes from the cylinder body 3, and the front end is allowed to reside in the sub-cylinder body 31.

  In addition, in this invention, the moving body 10 which is slidably accommodated in the sub-cylinder body 31 is held at the tip of the other rod body 43, and the moving body 10 is connected to the sub-cylinder body 31. The hydraulic oil in the sub chamber R3 in the sub cylinder body 31 flows down to the reservoir chamber R, and this will be described in detail later.

  Both rod bodies 42 and 43 are formed to have the same diameter, and the base ends of the rod bodies 42 and 43 are connected to the piston body 5 so that the pressure receiving areas at both ends of the piston body 5 are the same.

  Therefore, in this damper, since the cross-sectional areas of both the chambers R1, R2 are made the same, it is possible to embody the generation of damping force having the same characteristics when the fork body expands and contracts, and both damping valves By making the characteristics of 5a and 5b different, a desired damping force generation state can be realized.

  In this damper, since both chambers R1, R2 have the same cross-sectional area, the amount of hydraulic oil reciprocating between both chambers R1, R2 is the same. Although it is not necessary, since it has the reservoir chamber R, oil amount compensation and oil temperature compensation are performed.

  As shown in FIG. 2, the sub-cylinder body 31 is screwed to the lower end portion of the wheel side tube 2 and is attached to the inner bottom of the bottom member 6 that closes the lower end opening of the wheel side tube 2 under the arrangement of the seal member 61. The bottom member 6 stands up, and a fastening bolt 62 passes through the shaft core portion. The fastening bolt 62 protrudes upward from the inner bottom of the bottom member 6 and is screwed onto the lower end of the sub cylinder body 31. The connecting member 32 is screwed.

  When the tightening bolt 62 is tightened, the connecting member 32 is brought into close contact with the inner bottom of the bottom member 6 and the sub cylinder body 31 is erected on the shaft core portion of the wheel side tube.

  As shown in the figure, the sub-cylinder body 31 is integrally connected to the cylinder body 3 by being connected to a sealing member 33 that closes the lower end opening of the cylinder body 3 and forms a bottom portion that is the lower end portion of the cylinder body 3. It is connected continuously.

  The sub-cylinder body 31 has a communication hole 31a that allows communication between the reservoir chamber R and the inner sub-chamber R3 between the wheel-side tube 2 and an orifice 31b that is a plurality of communication holes in the vertical direction. A plurality of orifices 31b having a space in the vertical direction are sequentially closed by a moving body 10 described later that descends in the sub-cylinder body 31.

  The communication hole 31a opened in the sub-cylinder body 31 prevents the negative pressure by flowing hydraulic oil into the back side of the movable body 10 when the movable body 10 descends in the sub-cylinder body 31.

  The plurality of orifices 31b in the vertical direction are sequentially closed by the moving body 10 descending in the sub-cylinder body 31, and the amount of hydraulic oil flowing out from the sub-chamber R3 to the reservoir chamber R is gradually reduced. The speed at which the moving body 10 descends in the body 31 is slowed down, the operating speed of the damper, that is, the contraction speed of the fork main body is slowed down, and a damping force depending on the contraction position is generated.

  The orifice 31b can be freely selected by setting the interval and the number, and the diameter, so that the two-wheeled vehicle on which the front fork is mounted is an on-road type or an off-road type.

  As described above, according to the present invention, when the fork main body is contracted, the amount of hydraulic oil flowing out from the sub chamber R3 toward the reservoir chamber R gradually decreases as the stroke amount increases.

  Regarding this point, Japanese Patent Application Laid-Open No. 2005-257066 also discloses that the amount of hydraulic oil flowing out from the cylinder into the reservoir chamber gradually decreases as the moving body moves down in the cylinder.

  However, in the proposal disclosed in Japanese Patent Application Laid-Open No. 2005-257066, the rod body of the inverted damper is present on the axial center portion of the cylinder body. Therefore, the pressure receiving area in the cylinder body is the same as that of the cylinder body. The value obtained by subtracting the cross-sectional area of the rod body from the cross-sectional area is used as a reference.

  On the other hand, in the present invention, the pressure receiving area in the sub-cylinder body 31 is based on the cross-sectional area of the sub-cylinder body 31 as it is, so that the cylinder body and the sub-cylinder body 31 have the same diameter or substantially the same diameter. When compared with the diameter, the amount of hydraulic fluid passing through the orifice 31b increases, and more effective and preferable characteristics can be obtained when the occurrence of position-dependent damping force is observed.

  The moving body 10 is fitted to a holder 101 held on the outer periphery of the tip end portion of the other rod body 43 that is the rod body 4, and the holder 101 is movable up and down. An oil lock piece 102 is provided, and a check valve 103 is provided in a through hole 43a communicating with the other chamber R2 in the lower opening cylinder body 3 in the lower rod body 43.

  The outer periphery of the oil lock piece 102 has a leak gap from the inner circumference of the sub-cylinder body 31, and this leak gap exhibits a throttling effect when hydraulic oil passes through.

  And this oil lock piece 102 prevents the hydraulic oil in the sub chamber R3 from flowing into the back side of the oil lock piece 102 when the oil lock piece 102 is in the raised state while being fitted to the holder 101, The hydraulic oil behind the oil lock piece 102 is allowed to flow into the sub chamber R3 when in the lowered state.

  Therefore, in the moving body 10, when it moves down in the sub-cylinder body 31, the hydraulic oil in the sub-chamber R 3 flows out into the reservoir chamber R through the orifice 31 b described above.

  When the moving body 10 that has been lowered in the sub-cylinder body 31 reverses and rises in the sub-cylinder body 31, the hydraulic oil in the reservoir chamber R is returned to the sub-chamber R3 via the orifice 31b, and the moving body The hydraulic oil above 10 flows out into the reservoir chamber R through the communication hole 31a and the orifice 31b.

  On the other hand, when the moving body 10 descends in the sub-cylinder body 31 as shown in FIG. 3, the bottom portion of the sub-cylinder body 31 serves as an oil lock case, and the moving body 10 is placed in the oil lock case. By entering, an oil lock chamber R4 is formed and an oil lock effect is obtained.

  Thus, since the bottom part of the sub cylinder body 31 is an oil lock case, it is not necessary to assemble a separate part to provide the oil lock case, and it is possible to prevent a mischievous increase in the number of parts in the front fork. The mischievous increase in weight due to the increase in the number of points can also be prevented.

  Immediately before the formation of the oil lock chamber R4, the lowermost orifice 31b in the sub cylinder body 31 is closed by the oil lock piece 102. Therefore, the hydraulic oil that has been in the sub chamber R3 until then is oil lock. A cushioning effect is obtained that flows out above the moving body 10 between the piece 102 and the sub-cylinder body 31 and alleviates the impact at the time of maximum compression.

  When the lowermost orifice 31b in the sub-cylinder body 31 is closed by the oil lock piece 102, the oil lock chamber R4 is formed, and the movable body 10 is further lowered, that is, the fork main body is contracted. Is stopped.

  In addition, as shown in a virtual diagram in FIG. 1, the upper end of the wheel side tube 2 is brought into contact with the cushion material 11b held by the cap member 11 as to stop the contraction operation in the four body. It may be realized.

  As described above, according to the present invention, when the moving body 10 moves down in the sub cylinder body 31, as shown in FIG. Chamber R4 is formed.

  In this regard, Japanese Patent Application Laid-Open No. 2005-257066 also discloses that an oil lock chamber is formed at the bottom portion of the cylinder. The rod body in the damper is present, and therefore the pressure receiving area in the oil lock chamber is based on a value obtained by subtracting the cross-sectional area of the rod body from the cross-sectional area of the cylindrical body.

  On the other hand, in the present invention, the pressure receiving area of the oil lock chamber R4 is based on the sectional area of the sub-cylinder body 31 as it is, so that the cylinder body and the sub-cylinder body 31 have the same diameter or substantially the same diameter. If compared, the oil pressure at the time of oil lock increases, and an effective oil lock effect can be expected.

  The check valve 103 is connected to the other rod body 43 through a through hole (not shown) in order to communicate with the through hole 43a and the through hole 43a. It communicates with the other chamber R2 in the cylinder body 3, and allows the hydraulic oil in the sub chamber R3 to flow in.

  Therefore, in this front fork, with the damper incorporated in the shaft core part of the fork main body, hydraulic oil is injected into the reservoir chamber R in the fork main body, and the fork main body is expanded and contracted to check. The hydraulic oil can be filled into the damper via the valve 103.

  In addition, when hydraulic oil is injected into the damper via the check valve 103, it is necessary to allow the air in the one chamber R1 and the other chamber R2 to flow outside. A leakage gap that appears between the bearing 34a held on the inner periphery of the head member 34 that closes the upper end opening and the one rod body 42 is used.

  The check valve 103 may be disposed on the sealing member 33 that forms the bottom portion of the cylinder body 3 instead of being disposed on the movable body 10. In this case, Therefore, it is not necessary to open the through-hole 43 a in the shaft core portion of the other rod body 43.

  In addition, the check valve 103 is configured to have a steel ball and a coil spring that urges the check ball 103 in place of the check valve 103. However, the check valve 103 can be freely replaced as long as a predetermined check valve function can be realized. A configuration may be employed.

  As described above, the tightening bolt 61 is formed so-called innocuous, but, instead of this, although not shown, the bottom member 6 has a flow path that allows communication between the sub chamber R3 and the reservoir chamber R. In addition, a damping valve that enables generation of a damping force while selecting some of the flow rate of the hydraulic oil through an external operation may be provided in the flow path.

  Further, in the above description, the diameters of both rod bodies 42 and 43 constituting the double rod type damper are made the same. However, the present invention intends to realize the position-dependent damping characteristic and the most contraction operation. Of course, the diameters of the rod bodies 42 and 43 may be different from each other because the impact is mitigated at the time.

It is a front view which the front fork by this invention is divided | segmented, and is partially shown with a longitudinal cross section. FIG. 2 is a partial enlarged longitudinal sectional view showing a main part of the front fork of FIG. It is a figure which shows the operating state of the principal part of FIG. 2 similarly to FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car body side tube 2 Wheel side tube 3 Cylinder body 4 Rod body 10 Moving body 31 Sub cylinder body 31b Orifice 42 One rod body 43 Other rod body 102 Oil lock piece 103 Check valve R Reservoir chamber R1 One chamber R2 Other chamber R3 Sub chamber R4 Oil lock chamber S Suspension spring

Claims (4)

In a front fork in which a fork main body composed of a vehicle body side tube and a wheel side tube is urged in an extending direction by a suspension spring and has a double rod type damper at the shaft core, the damper connects the cylinder body and the rod body. The cylinder body stands up at the shaft core part of the wheel side tube under the sub cylinder body, and the rod body is suspended from the shaft core part of the vehicle body side tube while being composed of one rod body and the other rod body. The sub-cylinder body has a plurality of orifices in the vertical direction which allow communication between the reservoir chamber and the sub-cylinder body while the sub-cylinder body forms a reservoir chamber between the wheel-side tube, and the plurality of orifices in the vertical direction are forked. When the main body contracts, the sub-cylinder body is closed sequentially with a moving body that descends synchronously, and when the fork main body contracts, the moving body becomes a sub-cylinder body. Kicking front fork, characterized by comprising enters the oil lock case formed from the bottom portion. The front fork according to claim 1, wherein the other rod body of the rod body that is inserted into the cylinder body so as to be able to appear and retract has a moving body at a tip portion that is present in the sub chamber in the sub cylinder body. The movable body loosely fits the oil lock piece on the outer periphery, and the oil lock piece causes a plurality of vertical movements when descending in the sub cylinder body while causing a hydraulic oil leakage gap to appear between the movable body and the inner periphery of the sub cylinder body. The front fork according to claim 1, wherein the orifice is sequentially closed and enters an oil lock case formed of a bottom portion of the sub cylinder body when the sub cylinder body descends to define an oil lock chamber. The front fork according to claim 1, wherein the movable body has a check valve that allows the hydraulic oil in the sub-cylinder body to flow into the damper.

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