JP4898593B2 - Front fork - Google Patents

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 two-wheeled vehicle and absorbs road surface vibration that is input to the front wheel.

  As a front fork as a hydraulic shock absorber that is mounted on the front wheel side of a two-wheeled vehicle and absorbs road surface vibrations that are input to the front wheel, there have been various proposals so far. In addition to having a damping mechanism, the front fork has an oil lock mechanism that alleviates the impact at the time of the most contraction.

  That is, in the front fork disclosed in Patent Document 1, the handle-side tube is set as an outer tube and the wheel-side tube is set as an inner tube, and the inner tube is disposed inside the inner tube. Has a damping mechanism that makes the cylinder body.

  The front fork has an oil lock case inside the lower end of the inner tube, and an oil lock piece that fits into the oil lock case and constitutes an oil lock mechanism slides in the inner tube. It is held by the piston part of the storage.

Therefore, since the front fork disclosed in Patent Document 1 has a damping force generation mechanism, it absorbs road surface vibrations input to the front wheels of a running motorcycle and has an oil lock mechanism. The impact when the jumping motorcycle lands from the front wheel side can be mitigated.
Japanese Utility Model Publication No. 2-117990 (see FIG. 1)

  However, the proposal disclosed in Patent Document 1 does not have a problem in that the predetermined damping action and the oil lock action can be realized, but there is a slight problem in implementing this. May be pointed out.

  In other words, among the recent motorcycles, the damping effect on the front fork mounted on a motorcycle of large or medium size, which generally increases the displacement, is considered not only on the expansion side but also on the compression side, Moreover, it tends to be configured to allow each level adjustment, and thus the damping mechanism also tends to be complicated.

  From this, when the front fork disclosed in Patent Document 1 is used for a motorcycle, the front fork is suitable for a motorcycle or a bicycle that has a small displacement and is small in comparison.

  On the other hand, in a recent front fork, when it has a damping mechanism, it is often not replaced with an assembly structure as disclosed in the literature, but replaced with a cartridge damper.

  This is due to the recent improvement in the technical level. For example, when it is necessary to replace internal parts constituting the damping mechanism, it is less time-consuming to replace all parts if it takes time to disassemble and replace them. This is also due to the trend of achieving the goal quickly.

  From the above, when the front fork disclosed in Patent Document 1 is used for small motorcycles and bicycles, it is more versatile to replace the damping mechanism with a cartridge-like damper than to have an assembly structure. We can expect improvement.

  The present invention has been developed in view of such a current situation, and the object of the present invention is to provide a predetermined damping action and oil locking action when used for, for example, a small motorcycle or bicycle. It is to provide a front fork that can be embodied and is optimal for expecting improved versatility.

  In order to achieve the above-mentioned object, the front fork according to the present invention basically has a damper disposed in the fork main body composed of the handle side tube and the wheel side tube at the shaft core portion of the wheel side tube. A standing cylinder body, a rod body that is suspended from the shaft core portion of the handle-side tube and whose tip side is slidably inserted into the cylinder body, and a distal end portion of the rod body that is slidably received in the cylinder body A piston body held in the cylinder body, an oil lock mechanism between the piston body and the bottom end of the cylinder body, and a damping mechanism defined in the cylinder body by the piston body housed in the cylinder body. In the front fork having an extension side damping valve that allows communication between the upper chamber and the lower chamber, the piston body has an oil lock piece that forms an oil lock mechanism. In addition, an oil lock case that forms an oil lock mechanism together with the oil lock piece is disposed at the bottom end of the cylinder body, and the oil lock case connects the wheel side tube to connect the lower end of the fork main body to the axle. It is assumed that the shaft holder is fixed to the inner bottom portion of the axle holder by tightening a fastening bolt that passes through the shaft core portion in the inner bottom portion of the axle holder in the axial direction of the cylinder body while being seated on the inner bottom portion of the axle holder.

  Therefore, in the present invention, the damper in the fork main body composed of the handle side tube and the wheel side tube has the oil lock mechanism and the damping mechanism composed of the expansion side damping valve. It becomes possible to alleviate the impact and to develop a damping action when the damper is extended.

  On the other hand, in the present invention, the piston body has an oil lock piece that forms an oil lock mechanism, and an oil lock case that forms the oil lock mechanism together with the oil lock piece is disposed at the bottom end of the cylinder body. Therefore, when the damper is contracted to the maximum, the oil lock piece is fitted into the oil lock case, an oil lock phenomenon is expressed in the oil lock case, and a predetermined cushion effect can be obtained.

  In the present invention, the oil lock case is seated on the inner bottom of the axle holder that connects the wheel side tube and connects the lower end of the fork main body to the axle. Since the fastening bolt that penetrates in the axial direction of the body is fastened to the inner bottom portion of the axle holder, the damper can be attached to and detached from the fork main body by attaching and detaching the fastening bolt.

  In the following, the present invention will be described based on the illustrated embodiment, but even in the front fork according to the present invention, like the conventional front fork of almost all kinds, it is mounted on the front wheel side of the motorcycle, Absorbs road surface vibrations input to the front wheels (not shown) of the motorcycle during traveling.

  At this time, in the present invention, the motorcycle is not a motorcycle of a large or medium size according to the regulations that generally increases the displacement, but a motorcycle or a bicycle that is small to reduce the displacement by comparison. It is targeted.

  In the present invention, as shown in FIG. 1, the front fork is disposed in a fork main body comprising a handle side tube (not shown) as an upper end side member and a wheel side tube T as a lower end side member. It has a damper, and this damper enables a damping action when the fork main body is extended, and also makes it possible to alleviate the impact when the fork contracts.

  In addition, the fork main body is set to be an inverted type in which the handle side tube is made of a large diameter outer tube and the wheel side tube T is made of a small diameter inner tube.

  However, from the point of view of the present invention, instead of setting the fork body to an inverted type, the inner tube is set to the handle side tube and the outer tube is set to the upright type having the wheel side tube T. Also good.

  Also, an axle holder H is connected to the lower end portion of the wheel side tube T, and this axle holder H functions as a bracket for connecting the lower end portion of the fork main body to the axle of the front wheel. Connect together.

  Although not shown, the upper end portion of the handle side tube has a cap member that closes the upper end of the handle side tube, and this cap member has an upper end portion of a rod body 2 that constitutes a damper, which will be described later. The parts are connected in a separable manner.

  Therefore, in this fork main body, when the handle side tube is separated from the cap member and lowered, the rod body 2 in the damper connected to the cap member can be exposed. With the removal operation of 4, the damper can be extracted from the fork body.

  On the other hand, the damper has a cylinder body 1 erected on the shaft core portion of the wheel side tube T, and a tip end side which is the lower end side in the figure can be projected and retracted in the cylinder body 1 by being suspended from the shaft core portion of the handle side tube. The rod body 2 is inserted into the cylinder body 1, and the piston body 3 is slidably accommodated in the cylinder body 1 and is held at the distal end portion, which is the lower end portion of the rod body 2 in the drawing.

  In this damper, the cylinder body 1 has a bearing member 11 inside the head end portion which is the upper end portion in the figure, and the tip end side of the rod body 2 penetrates the shaft core portion of the bearing member 11. ing.

  At this time, the head end, which is the upper end of the cylinder body 1 in the drawing, is swaged inward to prevent the bearing member 11 from slipping out, and at the upper end of the swaged process, the guide member 12 Under the arrangement, the base end which is the lower end in the drawing of the suspension spring S is carried.

  Note that the suspension spring S has an upper end (not shown) that is locked at the upper end side of the handle-side tube, and therefore urges the fork main body in the extending direction. At this time, the damper is moved from the cylinder body 1 to the rod body 2. Is urged in the extending direction in which it protrudes.

  Therefore, in the fork main body, the contraction operation is overcome by overcoming the spring force of the suspension spring S, the expansion operation is performed by the spring force of the suspension spring S, and the damper is expanded and contracted in synchronization with the expansion and contraction operation of the fork main body.

  Further, in the damper, the cylinder body 1 has an oil lock case 13 integrally forming an oil lock mechanism, which will be described later, at a bottom end portion as a lower end portion in the drawing as shown in the figure. The oil lock case 13 closes the bottom end of the cylinder body 1 which is the lower end in the figure.

  The cylinder body 1 has a communication hole 1a that is opened in the vicinity of the bottom end, that is, in a portion that does not interfere with the upper end of the oil lock case 13, and the cylinder is interposed through the communication hole 1a. Communication between the inside of the body 1 and a later-described reservoir chamber R is allowed.

  By the way, in this damper, the cylinder body 1 is erected on the shaft core portion of the wheel side tube T. At this time, the oil lock case 13 connected to the bottom end portion of the cylinder body 1 is on the wheel side. The tube T is connected to the lower end of the fork main body to be connected to the axle and is seated on the inner bottom of the axle holder H, and the shaft core at the inner bottom of the axle holder H is tightened to penetrate the cylinder body 1 in the axial direction. The bolt 4 is fastened to the inner bottom portion of the axle holder H.

  At this time, as shown in the drawing, the threaded portion 4a of the tightening bolt 4 is screwed onto the inner periphery of the threaded portion 13a which is the lower half of the oil lock case 13, and the cylinder body 1 having the oil lock case 13 is engaged. In the present invention, the damper can be attached to and detached from the fork main body by attaching and detaching the tightening bolt 4.

  From the above, in the front fork of the present invention, it is possible to take out the damper from the fork main body. Therefore, for example, when it is necessary to replace the extension side damping valve 31 which is an internal part constituting the damping mechanism, The purpose can be achieved at an early stage by replacing the entire damper without having to disassemble the damper and replacing the parts.

  Incidentally, the oil lock case 13 described above has a partition wall portion 13a that prevents communication with the tightening bolt 4 that is the outer side of the cylinder body 1 in the axial direction. When removing the damper from the fork main body by detachment, there is no need to worry about oil leakage in the damper due to the removal of the fastening bolt 4.

  The rod body 2 has a tip end side, which is the lower end side in the figure, present in the cylinder body 1 and holds the piston body 3 under the distribution of the piston nut 5 at the tip end portion, which is the lower end part in the figure.

  At this time, the piston nut 5 functions as a lock nut that holds the piston body 3 in a fixed state at the tip of the rod body 2. In the present invention, the oil lock mechanism described later together with the oil lock case 13 described above is used. It also functions as an oil lock piece that forms.

  Therefore, in this piston nut 5, since an oil lock piece is not separately provided in order to form an oil lock mechanism, the piston nut 5 and the oil lock piece are not formed as separate parts. This is advantageous in terms of reduction.

  Not only the oil lock piece is not the piston nut 5, that is, the piston portion in the cylinder body 1 is independent of the piston nut 5, for example, compared to the case where it is connected to the tip of the rod body 2. This is advantageous in that the effective stroke is not reduced.

  The piston body 3 is slidably accommodated in the cylinder body 1 to define an upper chamber R1 and a lower chamber R2 in the cylinder body 1, and the upper chamber R1 and the lower chamber R2 are formed in the piston body 3. It is possible to communicate with each other via the opening port 3a, and the downstream side end of the port 3a is closed so as to be openable by the extension side damping valve 31 forming the damping mechanism according to the present invention.

  As shown in the figure, an extension spring 32 is housed in the upper chamber R1 in a state of being interposed by the rod body 2, and the extension spring 32 is located under the intervention of the valve stopper 33 in the piston body 3. It is carried on.

  On the other hand, in the illustrated damper, there is a wheel side tube T on the outside of the cylinder body 1, and a space between the wheel side tube T and the cylinder body 1 is set in the reservoir chamber R. The chamber R communicates with the lower chamber R2 in the cylinder body 1 through the communication hole 1a opened in the cylinder body 1.

  Therefore, in this damper, during the extension operation in which the piston body 3 ascends within the cylinder body 1, the hydraulic oil in the upper chamber R1 flows into the lower chamber R2 via the extension side damping valve 31, and the extension side damping is performed. A predetermined extension side damping force is generated by the valve 31.

  At this time, an amount of hydraulic oil corresponding to the exit rod volume lacking in the lower chamber R2 is replenished from the reservoir chamber R through the communication hole 1a, and when the communication hole 1a is an orifice, the extension side damping is performed. The generation of power can be expected.

  Further, in this damper, during the contraction operation in which the piston body 3 descends in the cylinder body 1, the hydraulic oil in the lower chamber R2 flows into the upper chamber R1 through the port 3a opened in the piston body 3.

  Then, at this time, an amount of hydraulic oil corresponding to surplus intrusion rod volume integral in the lower chamber R2 flows out to the reservoir chamber R through the communication hole 1a, and when the communication hole 1a is an orifice, the pressure side damping The generation of power can be expected.

  By the way, in the present invention, the damper has an oil lock mechanism between the piston body 3 and the bottom end portion of the cylinder body 1, and the oil lock mechanism includes an oil lock piece as a piston nut 5 and the oil lock mechanism. And an oil lock case 13 into which the pieces are fitted.

  In this oil lock mechanism, when the oil lock piece is fitted in the oil lock case 13, although not shown, the oil lock piece traps the hydraulic oil in the oil case 13 and exhibits an oil lock phenomenon. And prevents further contraction operation of the damper.

  At this time, the oil lock case 13 has a partition wall portion 13a that prevents the lower chamber R2 in the cylinder body 1 from communicating with the tightening bolt 4 described above.

  Therefore, in this oil lock mechanism, when the oil lock piece starts to be fitted into the oil lock case 13, the flow rate of the hydraulic oil between the two is gradually limited, and therefore the oil lock phenomenon occurs suddenly. Is not expressed, but a cushion effect that gradually develops the oil lock phenomenon can be obtained, and preferable impact relaxation can be achieved.

  From the above, in the oil lock case 13, as long as a predetermined cushion effect can be obtained with the oil lock piece and the oil lock phenomenon can be exhibited, for example, FIG. As shown, the bottom end 1b of the cylinder body 1 may be an oil lock case.

  At this time, the bottom end 1b of the cylinder body 1 is formed by, for example, pressure molding, for example, thickened by bulge processing and has a predetermined mechanical strength, and the tightening bolt 4 is attached to the inner peripheral thread 1c. Are screwed together.

  In the oil lock case shown in FIG. 2, since this comprises the bottom end portion 1 b of the cylinder body 1, the partition wall portion 13 a is not provided unlike the oil lock case 13 described above.

  Accordingly, the same can be said for the embodiment shown in FIG. 1, but even in the embodiment shown in FIG. 2, the fastening bolt 4 is distributed when passing through the shaft core portion of the axle holder H. The sealing performance by the packing 4b is important.

  Incidentally, according to the place shown in FIG. 2, the oil lock case is integrally formed by bulging the lower end portion 1b of the cylinder body 1, so that the oil lock case in the oil lock case is compared with the place shown in FIG. It is easy to align the axis line with the axis line in the cylinder body 1.

  However, in the embodiment shown in FIG. 1, it is only necessary to integrally connect the oil lock case 13 separately formed on the cylinder body 1 by welding, so that the existing cylinder body 1 can be used, and the product It will be advantageous in terms of cost.

It is a front view which partially fractures and shows the lower half side of the front fork by one Embodiment of this invention. It is a figure which shows the lower end part of the front fork by embodiment of a tank similarly to FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder body 1a Communication hole 1b Bottom end part 2 Rod body 3 Piston body 5 Piston nut which comprises an oil lock piece 4 Clamping bolt 13 Oil lock case 13a Partition part H Axle holder R Reservoir chamber R1 Upper chamber R2 Lower chamber

Claims (5)

A damper installed in the fork main body consisting of a handle side tube and a wheel side tube is a cylinder body standing upright on the shaft core portion of the wheel side tube, and is suspended from the shaft core portion of the handle side tube so that the tip side is inside the cylinder body. A rod body that is slidably inserted into the cylinder body, and a piston body that is slidably received in the cylinder body and is held at the tip of the rod body, between the piston body and the bottom end of the cylinder body A front fork having an oil lock mechanism and an extension side damping valve that allows communication between the upper chamber and the lower chamber defined in the cylinder body by a piston body housed in the cylinder body The piston body has an oil lock piece that forms an oil lock mechanism, and the oil lock mechanism is formed at the bottom end of the cylinder body together with the oil lock piece. The oil lock case is disposed, and the oil lock case is seated on the inner bottom portion of the axle holder that connects the wheel side tube and connects the lower end portion of the fork body to the axle, while the shaft core portion at the inner bottom portion of the axle holder is a cylinder. A front fork characterized by being fixed to an inner bottom portion of an axle holder by tightening a tightening bolt that penetrates in the axial direction of the body. The front fork according to claim 1, wherein the oil lock case is retrofitted to the bottom end portion of the cylinder body by welding or the like. The front fork according to claim 1 or 2, wherein the oil lock case is integrally formed at the bottom end of the cylinder body by pressure molding or the like. 4. The front fork according to claim 1, wherein the oil lock case has a partition wall portion that prevents communication with a tightening bolt side that is an outer side in the axial direction of the cylinder body. 5. A reservoir chamber is defined between the cylinder body and the wheel side tube, and the reservoir chamber and the cylinder body are communicated with the cylinder body through a communicating hole for opening. The front fork according to claim 3 or claim 4.

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