JP2012031999A - Front fork - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a front fork which ensures the everlasting durability of a sliding contact ring when a sheet pipe as a component is diverted.SOLUTION: The front fork includes: a wheel side tube 1; a vehicle body side tube 2 inserted into the wheel side tube 1 in an advanceable/retractable manner; a sheet pipe 3 erected on the shaft center part of the wheel side tube 1; a suspended spring S which energizes the vehicle body side tube 2 in the extension direction; and the sliding contact ring 4 which is in sliding contact with the inner circumference of the vehicle body side tube 2 while being held at the upper end part of the sheet pipe 3, wherein the sliding contact ring 4 is held by an annular holder 5 connected to the upper end part of the sheet pipe 3 and the lower end of the suspended spring S is supported by the holder 5.

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 the front wheel side of a two-wheeled vehicle and absorbs road surface vibrations that are input to the front wheel of the two-wheeled vehicle that is running.

There have been various proposals for a front fork as a hydraulic shock absorber that is mounted on the front wheel side of a two-wheeled vehicle and absorbs road vibration input to the front wheel of the two-wheeled vehicle that is running. Has proposed that the seat pipe standing on the shaft core portion of the wheel side tube constituting the front fork is formed of a press-formed product.

The front fork is inserted into the wheel side tube so that the vehicle body side tube can protrude and retract. However, the seat pipe made of the press-molded product faces the outer peripheral side of the upper end, that is, the side facing the vehicle side tube. It has a groove formed in an annular shape, and has a slidable contact ring that is housed in the groove and slidably contacts the vehicle body side tube.

By the way, the groove formed in the above-described laterally annular shape is formed by bending the upper end portion of the seat pipe, and the sliding contact ring is a check valve and can be accommodated in the annular groove so that it can be raised and lowered. is there.

Therefore, in the proposal disclosed in Patent Document 1, since the seat pipe is made of a press-formed product, the weight of the component is compared with the case where the seat pipe is made of a cast product or a machined product from a pipe body. Can be reduced and the cost of parts can be reduced.

Japanese Patent Laid-Open No. 9-217780 (see paragraphs 0004 and 0023, FIGS. 1 and 3 in the specification)

However, there is a possibility that the front fork disclosed in Patent Document 1 described above has a slight problem in expecting further improvement in versatility.

In other words, including the front fork disclosed in the above-mentioned document, diversion of the seat pipe as a component is intended to reduce the component cost and product cost of the front fork.

When diverting the seat pipe, if the diameter of the vehicle body side tube with which the sliding contact ring comes into sliding contact becomes large, the sliding contact ring is formed with a so-called large diameter. Although the inner diameter of the sliding contact ring is not changed without changing the outer diameter of the annular groove that accommodates the ring, the outer diameter of the sliding contact ring that is in sliding contact with the vehicle body side tube is increased to increase the radial direction of the sliding contact ring. Increase the width.

Therefore, the sliding contact ring is subjected to a large hydraulic action by increasing its pressure receiving area. Therefore, it is not easy to guarantee the mechanical strength of the sliding contact ring, and the permanent durability of the sliding contact ring is increased. There is a risk of injuring harmful effects.

The present invention was devised in view of the above circumstances, and its purpose is to guarantee the permanent durability of the sliding contact ring when practicing diversion of a seat pipe as a part. It is to provide a front fork that is optimal for expecting improvement in its versatility.

In order to achieve the above-described object, the means of the present invention includes a wheel-side tube, a vehicle body-side tube that is inserted in the wheel-side tube so as to be able to protrude and retract, and a seat pipe that stands on the shaft core portion of the wheel-side tube. A front fork comprising: a suspension spring that urges the vehicle body side tube in the extending direction; and a sliding contact ring that is held by an upper end portion of the seat pipe and slidably contacts the inner periphery of the vehicle body side tube. The contact ring is held in an annular holder connected to the upper end of the seat pipe, and the lower end of the suspension spring is supported by the holder.

Therefore, in the present invention, the sliding ring that is slidably contacted with the vehicle body side tube is held by the annularly formed holder connected to the upper end portion of the seat pipe. Even if the outer diameter of the upper end portion where the ring is disposed is unchanged, it is possible to cope with the slidable ring without increasing the radial dimension by selecting the diameter of the holder.

Furthermore, since the lower end of the suspension spring is carried by the holder, the suspension spring can be set short, which can contribute to a reduction in the overall weight of the front fork.

It is a partial semi-longitudinal longitudinal cross-sectional view which shows the principal part of the front fork by one Embodiment of this invention. It is the fragmentary longitudinal cross-sectional view which expands and shows the principal part of the front fork concerning a reference example.

The present invention will be described below based on the embodiment shown in FIG. 1 and the reference example of FIG.

As shown in FIG. 1, the front fork according to the embodiment of the present invention includes a wheel side tube 1, a vehicle body side tube 2 inserted into the wheel side tube 1 so as to be able to protrude and retract, and an axis of the wheel side tube 1. A seat pipe 3 that stands up at the seat, a suspension spring S that biases the vehicle body side tube 2 in the extending direction, and a sliding contact ring 4 that slidably contacts the inner periphery of the vehicle body side tube 2 while being held at the upper end of the seat pipe 3. And.

The sliding contact ring 2 is held in an annular holder 5 connected to the upper end of the seat pipe 3, and the lower end of the suspension spring S is supported by the holder 5.

This will be described in detail below.

In this front fork, the seat pipe 3 stands on the shaft core portion of the wheel side tube 1, and the sliding contact ring 4 held on the upper end portion of the seat pipe 3 is connected to the upper end portion of the seat pipe 3. It is slidably contacted with the inner diameter portion which is the shaft portion of the vehicle body side tube 2 while being held by the annularly formed holder 5.

As shown in the figure, the seat pipe 3 is made of a press-formed product obtained by press-molding a metal pipe having a uniform thickness into a predetermined shape. Grooves 3a formed in a laterally annular shape are provided on the opposing outer peripheral portions.

Incidentally, as disclosed in Patent Document 1 described above, in the conventional front fork, a sliding contact ring is accommodated in the annular groove 3a, and the sliding contact ring is accommodated in the groove 3a. Was in sliding contact with the opposite body side tube.

On the other hand, as will be described in detail later, in the present invention, the sliding contact ring 4 is held by an annularly formed holder 5 connected to the upper end of the seat pipe 3 as shown in the embodiment in FIG. Alternatively, as shown in the reference example of FIG. 2, the annular holder 5 is accommodated in an annular groove 3 a at the upper end portion of the seat pipe 3 formed by bending.

Even in this front fork, the vehicle body side tube 2 is urged in the extending direction to be pulled out of the wheel side tube 1 by the spring force of the suspension spring S. At this time, the embodiment shown in FIG. In the embodiment, the lower end of the suspension spring S is carried by the holder 5. In the reference example shown in FIG. 2, the lower end of the suspension spring S is carried by the upper end portion of the seat pipe 3.

And when the lower end of suspension spring S is carry | supported by the holder 5, the suspension spring S can be set short and it can contribute to reduction of the whole weight in a front fork.

On the other hand, in the front fork, a piston portion 6 is provided at the lower end portion of the vehicle body side tube 2, and the piston portion 6 is integrally connected to the lower end portion of the vehicle body side tube 2; The piston case 61 includes a piston 62 slidably contacting the shaft portion of the seat pipe 3 while being held up and down by the piston case 61.

The piston 62 rises inside the piston case 61 as the pressure increases below the piston 62 during the contraction operation of the front fork in which the vehicle body side tube 2 is immersed in the wheel side tube 1. The oil is allowed to flow into the upper oil chamber R1 above the piston 62.

And conversely, the vehicle body side tube 2 descends inside the piston case 61 as the pressure of the upper oil chamber R1 above the piston 62 increases when the front fork extends out of the wheel side tube 1, and the upper oil The hydraulic oil in the chamber R1 is prevented from flowing out below the piston 62.

At this time, the seat pipe 3 has a plurality of orifices 3b and 3c that allow the communication on the inner and outer peripheral sides of the seat pipe 3 in series with the shaft portion in the axial direction. Therefore, the piston 62 is connected to the orifice 3b, When ascending from the lower side of 3c, the sliding contact ring 4 is also arranged, so that the hydraulic oil in the upper oil chamber R1 above the piston 62 flows into the seat pipe 3 through the orifices 3b and 3c. Then, the extension side damping force is generated.

As shown in FIG. 1, after the piston case 61 rises up and the piston 62 passes through the orifices 3b and 3c, the orifices 3b and 3c are positioned below the piston 62. 4, the oil lock phenomenon on the extension side in which the hydraulic oil is confined in the upper oil chamber R <b> 1 above the piston 62 is expressed, and the shock at the time of the extension operation is alleviated.

In the illustrated embodiment, the extension spring S1 is supported on the upper end of the piston case 61. When the piston case 61 rises to the highest level, the extension spring S1 reaches the uppermost end of the seat pipe 3. Shrink to relieve impact.

Incidentally, the above-described piston case 61 has a reduced diameter portion 61a, and although not shown, the lower end of the wheel side tube 1 during the most contraction operation in which the vehicle body side tube 2 is immersed in the wheel side tube 1 with a large stroke. An oil lock piece held in the outer periphery of the lower end portion of the seat pipe 3 is introduced into the inside of the reduced diameter portion 61a so as to develop a pressure-side oil lock phenomenon so that an impact at the time of the most contraction operation is generated. ease.

Regarding the sliding contact ring 4 and the holder 5 described above, first, the sliding contact ring 4 is formed of the same material as that conventionally provided as this kind of sliding contact ring, and is similar to the conventional one. Formed in the structure.

Next, the holder 5 is formed in an annular shape so as to hold the slidable contact ring 4 on the outer peripheral side portion, and in the illustrated case, the holder 5 is placed in a state of being placed on the upper end portion of the seat pipe 3 and the lower end thereof is arranged. They are connected together by caulking.

And this holder 5 has the groove | channel 5a formed in the sideways annular shape in the outer peripheral part, ie, the side part which opposes the vehicle body side tube 2, and the sliding contact ring 4 is accommodated in this groove | channel 5a.

Therefore, by arranging the sliding contact ring 4 on the shaft portion of the vehicle body side tube 2, the reservoir chamber R above the sliding contact ring 4 is below the sliding contact ring 4 and outside the seat pipe 3. It is shut off from the upper oil chamber R1.

By the way, the slidable contact ring 4 in the present invention is a check valve that is held in the groove 5a of the holder 5 so as to be movable up and down, and is a front fork in which the vehicle body side tube 2 comes out of the wheel side tube 1. When the upper oil chamber R1 is increased in pressure during the extension operation, it rises in the groove and prevents the hydraulic oil in the upper oil chamber R1 from flowing out into the reservoir chamber R. When the front fork immersing into the tube 1 is contracted, the lower oil chamber R1 is lowered with a negative pressure, and the hydraulic oil in the reservoir chamber R is allowed to flow into the lower oil chamber R1.

Therefore, when the sliding contact ring 4 is used as a check valve, the piston 62 reverses and descends after the oil lock phenomenon on the extension side in the upper oil chamber R1 due to the highest rise of the piston 62 described above. The expression of the negative pressure phenomenon in the oil chamber R1 can be effectively prevented.

Further, the check valve which is the sliding contact ring 4 facilitates the flow of the hydraulic oil injected into the reservoir chamber R into the upper oil chamber R1 when the front fork is assembled.

In the front fork formed as described above, the slidable contact ring 4 slidably contacting the vehicle body side tube 2 is held by the annularly formed holder 5 connected to the upper end portion of the seat pipe 3. Even if the outer diameter of the upper end portion where 3 is a diverted part and the sliding contact ring 4 is arranged is unchanged, the radial dimension of the sliding contact ring 4 is increased unnecessarily by selecting the diameter of the holder 5 It can respond without any problems.

As a result, when the seat pipe 3 is diverted in the sliding contact ring 4, the sliding contact ring 4 is not formed to have a large diameter even when the diameter of the vehicle body side tube 2 in sliding contact with the sliding contact ring 4 increases. Thus, the pressure receiving area is not increased, and therefore, the sliding contact ring 4 is not subjected to a large hydraulic action, so that the mechanical strength of the sliding contact ring 4 is easily ensured, and the permanent durability of the sliding contact ring 4 is ensured. Can be guaranteed.

By the way, in the place shown in FIG. 2, the holder 5 is housed in the annular groove 3a at the upper end portion of the seat pipe 3 formed by bending. The ring 4 is directly stowed.

From this, if it is conventional, the size of the annular groove 3a, in particular, the height of the annular groove 3a in the vertical direction in the figure is sufficient to accommodate the sliding ring 4. However, in this embodiment, it may be said that there is a disadvantage that it is important to form the holder 5 holding the sliding contact ring 4 so that the holder 5 can be accommodated.

However, according to this reference example, the sliding contact ring 4 can be accommodated and held in the annular groove 5a of the holder 5 before the holder 5 is accommodated in the annular groove 3a. As compared with the case where the sliding ring 4 is held in the groove 5a of the holder 5 accommodated in the groove 3a, there is an advantage that the assembling work is facilitated.

Further, according to this reference example, since the lower end of the suspension spring S is carried by the upper end portion of the seat pipe 3, it is advantageous in that the holder 5 need not be formed by an axial force member.

In the above description, the case where the sheet pipe embodying the present invention is made of a press-formed product has been described as an example. However, the present invention is intended to reduce the component cost and the product cost due to the diversion of the component. Therefore, it goes without saying that the present invention can be realized even when the sheet pipe is made of a cast product or a cut product from a pipe body.

DESCRIPTION OF SYMBOLS 1 Wheel side tube 2 Car body side tube 3 Seat pipe 3a, 5a Groove 3b, 3c Orifice 4 Sliding contact ring 5 Holder 6 Piston part 61 Piston case 62 Piston S Suspension spring S1 Extension spring

Claims (4)

A wheel-side tube, a vehicle body-side tube inserted in the wheel-side tube so as to be able to appear and retract, a seat pipe standing on an axial core portion of the wheel-side tube, and a suspension spring for urging the vehicle-body side tube in an extending direction And a front fork having a sliding contact ring that is slidably contacted with the inner periphery of the vehicle body side tube while being held by the upper end portion of the seat pipe, an annular holder that connects the sliding contact ring to the upper end portion of the seat pipe A front fork which is held inside and has the lower end of the suspension spring supported by the holder. The front fork according to claim 1 or 2, wherein the holder has a groove formed in a laterally annular shape on a side portion facing the vehicle body side tube, and a sliding contact ring is accommodated in the groove. The front fork according to claim 1, wherein the sliding contact ring is held by the holder so as to be movable up and down and serves as a check valve. The front fork according to claim 1, 2 or 3, wherein the seat pipe is made of a press-formed product.

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