JP5207166B2 - 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 mounted on a front wheel side of a two-wheeled vehicle and absorbs road surface vibrations input to the front wheel while suspending the front wheel of the two-wheeled vehicle.

  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 surface vibrations input to the front wheel while suspending the front wheel of the two-wheeled vehicle.

  Among them, for example, as disclosed in Patent Document 1, in many front forks, an air chamber having an oil level as a boundary above the inside of the fork main body composed of a vehicle body side tube and a wheel side tube. Is defined.

  Therefore, a front fork having an air chamber above the inside of the fork main body also has a suspension spring made up of a coil spring in many cases. It can be expected that a spring characteristic composed of a resultant force of the air spring force due to expansion and contraction of the chamber is exhibited.

And when the fork main body has, for example, an adjustment rod that protrudes and retracts in the axial direction, the volume of the air chamber can be adjusted by adjusting the volume of the air chamber, that is, the optimal air spring force, A favorable spring characteristic in the front fork is obtained.
Japanese Patent Laid-Open No. 2003-184931 (abstract, paragraphs 0012, 0015, 0038, and FIG. 1 in the specification)

  However, in the front fork disclosed in Patent Document 1 described above, a preferable spring characteristic can be theoretically obtained, but there is a possibility that it is pointed out that there is a slight defect in view of the actual use. .

  That is, for example, in the case of a front fork, when the outer tube having a large diameter is used as the vehicle body side member, the fork is generally compared with the case where the inner tube having a small diameter is used as the vehicle body side member. The volume of the air chamber defined above the inside of the main body becomes large.

  Under such circumstances, even if the adjustment rod is protruded and retracted in the axial direction of the fork body, the volume change rate of the air chamber due to the protrusion and removal of the adjustment rod is small, and therefore, effective spring characteristics depending on the change of the air spring force Adjustment is not easy.

  Therefore, it is good to select the optimal volume of the air chamber by adjusting the capacity of the hydraulic oil, but the amount exceeds the amount necessary to obtain the damping characteristics of the built-in damper, for example. A large amount of hydraulic oil was required.

  As a result, the amount of oil is increased to realize the optimal air spring force, which hinders the intention to reduce the weight of the front fork and also impedes the intention to reduce the product cost. .

  The present invention was devised in view of such a current situation, and the object of the present invention is to enable an optimal air spring force to be exhibited while reducing the amount of hydraulic oil accommodated therein. It is to provide a front fork that can embody spring characteristics and is optimal for expecting improved versatility.

In order to achieve the above-described object, the structure of the front fork according to the present invention is basically a suspension spring that is built in a fork main body having a vehicle body side tube and a wheel side tube while incorporating a damper. In a front fork that is urged by a force in an extending direction and has an air chamber that borders the oil level, the damper is erected in the wheel side tube, and the vehicle body side tube A rod body that is suspended and has a lower end inserted through the cylinder body, and an air chamber volume reducing means is arranged in series at the upper end of the suspension spring, the lower end of which is supported on the upper end of the cylinder body,
An upper end of the air chamber volume reducing means is locked to an upper end portion of the rod body, and the air chamber volume reducing means includes an upper cap and a lower cap whose inner circumference is separated from the outer circumference of the rod body, and an outer circumference of the upper cap. the sub-pipes of a pipe which is continuously provided between the outer periphery of the lower cap, the inner periphery is continuously provided between the inner periphery of the inner periphery and the lower cap of the upper cap is separated from the outer periphery of the rod body and, The upper cap, the lower cap, the pipe, and the sub-pipe have an air chamber defined by the pipe and the sub pipe .

Therefore, in the present invention, the rod end of the rod body suspended from the upper end of the vehicle body side tube or the damper formed in the vehicle body side tube while the base end is carried by the upper end of the suspension spring. Since the air volume reducing means locked to the upper end portion is connected in series so as to overlap the suspension spring from above, the air chamber volume above the suspension spring is reduced, and the air chamber is not increased without increasing the amount of hydraulic oil. Can be set to an optimal size.
In the present invention, a gap appears between the air volume reducing means and the outer periphery of the rod body, and the gap allows the oil level to rise, that is, allows the hydraulic oil to enter. When the air remaining in the gap is compressed, the oil lock effect depending on the hydraulic oil that enters can be expected, and the position-dependent spring characteristics can be expected to be exhibited.

In the following, the present invention will be described based on the embodiment shown in FIG. 1 as a principle diagram , FIG. 2 as a reference diagram, and FIG . 3 as a specific diagram of the main part. The wheel-side tube 2 is inserted in a retractable manner so that the shaft core portion of the fork body is energized in the extension direction by the spring force of the suspension spring S incorporated therein while incorporating a single rod type damper. It has an air chamber A as a boundary.

  To explain a little, the illustrated front fork is set up as an inverted type in which the vehicle body side tube 1 is made of a large diameter outer tube and the wheel side tube 2 is made of a small diameter inner tube. From above, the vehicle body side tube 1 may be configured as an upright type in which the wheel side tube 2 is formed of a small diameter inner tube and the wheel side tube 2 is formed of a large diameter outer tube.

  The damper is inserted into the cylinder body 3 erected on the shaft core portion of the wheel side tube 2 so that the rod body 4 can be projected and retracted at the shaft core portion of the vehicle body side tube 1. A piston portion 5 provided in the lower end portion of the rod body 4 connected to the upper end portion and sliding in the cylinder body 3 has an extension oil chamber R1 as an upper oil chamber and a pressure oil chamber R2 as a lower oil chamber in the cylinder body 3. Is defined.

  The piston portion 5 includes an extension side damping valve 5a that generates an extension side damping force having a predetermined magnitude by allowing the hydraulic oil from the extension side oil chamber R1 to pass to the pressure side oil chamber R2, and the extension side damping valve. And a check valve 5b in parallel with 5a.

  The inside of the fork main body, that is, between the wheel side tube 1 and the cylinder body 3 and above the cylinder body 3 communicating with this is a reservoir chamber R. The reservoir chamber R is bordered by the oil level O. The air chamber A is filled with an inert gas or the like.

  The reservoir chamber R communicates with the pressure side oil chamber R2 in the cylinder body 3 via a pressure side damping valve 6a disposed in the bottom portion (or the base valve portion in the cylinder body 3) 6 of the fork main body. A check valve 6b is arranged in parallel with the compression side damping valve 6a.

  The suspension spring S is shown in the figure, and the lower end is supported on the upper end of the cylinder body 3 while the upper end is locked to the lower end of the air chamber volume reducing means 10 described later, and the wheel side tube 2 is connected to the vehicle body side tube 1. The fork main body is urged in the extending direction in the direction in which the fork body comes out.

  Therefore, in this front fork, when the fork main body is expanded and contracted, a spring characteristic composed of a combined force of a spring force due to expansion and contraction of the suspension spring S and an air spring force due to expansion and contraction of the air chamber A can be realized. In the damper, when the rod body 4 protrudes and retracts with respect to the cylinder body 3, a predetermined amount of damping force is generated by the extension side damping valve 5a and the compression side damping valve 6.

  Incidentally, the hydraulic oil that is deficient in the pressure side oil chamber R2 when the damper is extended is replenished from the reservoir chamber R, and the excess hydraulic oil in the pressure side oil chamber R2 is discharged into the reservoir chamber R when the damper is contracted.

By the way, the air chamber volume reducing means 10 is engaged with the upper end of the vehicle body side tube 1 or the upper end of the rod body 4 forming a damper while the lower end is supported on the upper end of the suspension spring S.

  The air chamber volume reducing means 10 is arranged so that the occupied volume in the air chamber A defined by the oil level O in the reservoir chamber R is set to an optimum value. May be arbitrarily configured.

  However, this air chamber volume reduction means 10 reduces the amount of hydraulic oil stored in the reservoir chamber R by optimizing the occupied volume in the air chamber A, and as a result, can reduce the weight of the front fork. To.

  In view of this, it is not preferable to select a configuration in which the specific gravity is larger than the specific gravity of the hydraulic oil in forming the air chamber volume reducing means 10. And as shown in FIG. 3, it is preferable that the air chamber volume reduction means 10 is formed in the space | gap structure which makes an inside empty.

  On the other hand, the air volume reducing means 10 makes it difficult for buckling to occur without forming the suspension spring S unnecessarily long, and also reduces the weight of the fork main body by shortening the suspension spring S. I have to.

  2 and 3, the fork main body has an adjuster 8 on the upper end cap 7 of the vehicle body side tube 1, and the upper end position of the suspension spring S can be adjusted by rotating the adjuster 8. Yes.

  From this, the air volume reducing means 10 is formed in an axial force member structure having mechanical strength that is not deformed by the spring force of the suspension spring S, and is formed so as to be movable in the axial direction of the fork main body. It is preferable.

The air volume reduction means 10 includes an upper cap 11, a lower cap 12, and a pipe 13, which will be described below with reference to FIG . 2 as a reference diagram and FIG . 3 as a specific diagram of the main part. A chamber A1 that is cut off from the air chamber A is defined inside.

  The upper cap 11 has a predetermined mechanical strength and does not increase the weight unnecessarily. For example, the upper cap 11 is formed of a synthetic resin material so as to have a substantially funnel-like cross-sectional shape. It is locked to the upper end or the upper end of the rod body 4.

Specifically, as shown in FIGS. 2 and 3 , the upper end portion 11 a which is a large diameter portion of the upper cap 11 is interposed on the outer periphery of the lower end portion 7 a of the cap 7 which connects the upper end portion of the rod body 4. The

The upper cap 11 is in the illustrated embodiment, and the air volume reducing means 10 is movable in the axial direction of the fork main body, so that the upper end portion 11a is connected to the adjuster 8 so as to be movable up and down. The locking piece 8a is locked.

  Similarly to the upper cap 11, the lower cap 12 has a predetermined mechanical strength and does not unnecessarily increase the weight. For example, the lower cap 12 is formed in a ring shape having a concave groove with a synthetic resin material, and has a lower end at the upper end of the suspension spring S. The inner periphery is adjacent to the outer periphery of the rod body 4 under an airtight structure.

  Since the pipe 13 is an axial force member, the pipe 13 is made of, for example, a metal pipe having a predetermined mechanical strength, and does not interfere with the inner periphery of the wheel side tube 2. A chamber A1 that is connected to the airtight structure and is shut off from the air chamber A is defined.

  In the air chamber volume reducing means 10 formed as described above, as long as it is disposed at a predetermined position, the air chamber A defined by the oil surface O as a boundary is provided inside the fork main body. Therefore, the volume of the air chamber A required for realizing the generation of the optimal air spring force can be set to an optimal value.

  From this, in this air chamber volume reducing means 10, compared with the case where the amount of hydraulic oil to be stored is increased in order to optimize the volume occupied by the air chamber A, the amount of hydraulic oil is reduced. To reduce weight and reduce material costs.

  And in this air chamber volume reduction means 10, when this is pushed down in the figure, for example, the upper end position of the suspension spring S is lowered, and the spring force of the suspension spring S is increased.

  The above is the operational effect of the air volume reducing means 10 in the present invention. In the embodiment shown in FIG. 3, the following consideration is given, and this will be described a little.

  In addition, in the place shown in FIG. 3, where the configuration is the same as that shown in FIG. Omitted.

That is, in the air volume reducing means 10 shown in FIG. 3, the upper cap 11 and the lower cap 12 whose inner circumference is separated from the outer circumference of the rod body 4, and the outer circumference of the upper cap 11 and the outer circumference of the lower cap 12. A pipe 13 provided between the inner circumference of the upper cap 11 and the inner circumference of the lower cap 12, a sub pipe 14 having an inner circumference away from the outer circumference of the rod body 3, the upper cap 11 and the lower cap 12, a pipe 13, and a sub-pipe 14 have an air chamber A defined inside and a container chamber A 1 that is blocked.

  Therefore, a gap S1 appears between the air volume reducing means 10 and the outer periphery of the rod body 4, and this gap S1 allows the oil level O to rise, that is, allow the hydraulic oil to enter, At this time, the air remaining in the gap S1 can be compressed, and an oil lock effect can be expected depending on the hydraulic oil that enters, and a position-dependent spring characteristic can be expected to be exhibited.

  In the case of this embodiment, the air volume reducing means 10 is arranged at a predetermined position, particularly because the lower cap 12 can be moved without sliding on the outer periphery of the rod body 4. Compared with the case where the air volume reducing means 10 shown in FIG. 2 is provided, the arrangement work is facilitated.

  In view of this, in the embodiment shown in FIG. 2, although not shown in order to improve the workability when the air volume reducing means 10 is disposed at a predetermined position, Alternatively, the outer diameter of the rod body 4 on which the lower cap 12 slides may be reduced in diameter.

  In addition, as described above, the pipe 13 is connected to the upper cap 11 and the lower cap 12 by so-called retrofitting, but instead of this, the pipe 13 is integrated with the upper cap 11 or the lower cap 12 although not shown. Or the pipe 13 may be integrally connected to the upper cap 11 and the lower cap 12. In this case, the number of parts is reduced and the air volume reducing means 10 is disposed. There is an advantage of facilitating work and removal work.

It is a figure which shows the front fork of this invention in principle. It is a partial semi-longitudinal longitudinal cross-sectional view which shows the principal part of the front fork of a reference example . It is a partial semi-longitudinal longitudinal cross-sectional view which shows the principal part of the front fork by embodiment of this invention .

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Car body side tube 2 Wheel side tube 3 Cylinder body 4 Rod body 10 Air chamber volume reduction means 11 Upper cap 12 Lower cap 13 Pipe 14 Sub pipe A Air chamber A1 Container chamber O Oil surface S Suspension spring

Claims (5)

A fork main body having a vehicle body side tube and a wheel side tube is energized in the extension direction by the spring force of a suspension spring built in while incorporating a damper, and has an air chamber with an oil level as a boundary. In the front fork, the cylinder body includes: a cylinder body in which the damper is erected in the wheel side tube; and a rod body which is suspended in the vehicle body side tube and whose lower end is inserted into the cylinder body. The air chamber volume reducing means is arranged in series at the upper end of the suspension spring on which the lower end is carried on the upper end of
An upper end of the air chamber volume reducing means is locked to an upper end portion of the rod body, and the air chamber volume reducing means includes an upper cap and a lower cap whose inner circumference is separated from the outer circumference of the rod body, and an outer circumference of the upper cap. the sub-pipes of a pipe which is continuously provided between the outer periphery of the lower cap, the inner periphery is continuously provided between the inner periphery of the inner periphery and the lower cap of the upper cap is separated from the outer periphery of the rod body and, A front fork comprising the upper cap, the lower cap, the pipe, and the sub-pipe, and the air chamber defined therein and the chamber closed . The front fork according to claim 1, wherein the air chamber volume reducing means is formed in a void structure by the chamber . The front fork according to claim 1 or 2, wherein the air volume reducing means is movable in the axial direction of the fork main body. Said upper cap is engaged with the upper end portion of the vehicle body side tube, or locked to the upper end portion of the rod member, said lower cap is engaged the upper end of the suspension spring, the pipe and the axial force member The front fork according to claim 1, 2, or 3. In the air volume reducing means, the upper cap and the pipe connected to the outer periphery of the upper cap, or the lower cap and the pipe connected to the outer periphery of the lower cap are integrally formed. The front fork according to claim 4.

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