JP2856776B2 - Inverted front fork - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an inverted front fork used for a motorcycle.

(Prior art) Inverted front forks used for motorcycles are:
An inner tube is slidably fitted to each of a pair of left and right outer tubes from below, and the outer tubes are connected by an upper bracket and a lower bracket, which are connecting members, and a front wheel is provided at a lower end of the inner tubes. It is rotatably supported.

(Problems to be Solved by the Invention) However, in the conventional inverted front fork for a motorcycle, since the outer tube and the connecting member are formed separately, it is necessary to connect both of them, and assembling man-hours In addition, not only the number of parts increases, but also the accuracy (particularly, parallelism) after assembly cannot be kept high due to the processing error of each part, and the operability may be deteriorated.

Also, since the connecting member such as the lower bracket protrudes to the side of the outer tube, when the handle is turned to the maximum, the connecting member may interfere with the fuel tank. It is necessary to provide a concave portion in advance, and there is a problem that the capacity of the fuel tank is reduced by the concave portion.

The present invention has been made in view of the above problems, and an object thereof is to provide an inverted front fork for a motorcycle which can reduce the number of assembling steps and the number of parts, improve processing and assembling accuracy, and the like. To provide.

(Means for Solving the Problems) In order to achieve the above object, according to the present invention, an inner tube is slidably fitted to each of a pair of left and right outer tubes from below, and the outer tubes are attached to upper and lower connecting members. In the inverted front fork for a motorcycle, the outer tube and the upper and lower connecting members are cast and integrated, and the lower part of the steering shaft inserted into the head pipe is fixed to the lower connecting member, and The upper screw portion of the shaft is fastened to the crown member with a nut, the crown member is fixed to the upper connecting member with a bolt, and a handle stay is integrally formed with each outer tube.

(Operation) According to the present invention, the pair of left and right outer tubes and the upper and lower connecting members are integrally cast, so that there is no need to join them, and the number of assembly steps and the number of parts can be reduced. Since the handle stay is formed integrally with each outer tube, the number of assembly steps and the number of parts can be further reduced.

Also, instead of connecting the separately processed outer tube and the connecting member as in a conventional inverted type front fork, machining is performed on an integrated outer tube and connecting member. Therefore, the machining and assembling accuracy is increased, and the operability of the inverted front fork is improved.

Further, since the connecting member does not protrude to the side of the outer tube as in the prior art, interference between the connecting member and the fuel tank in a motorcycle is avoided, and interference between the fuel tank and the connecting member is avoided. There is no need to provide a recess, and the capacity of the fuel tank can be increased.

(Example) Hereinafter, an example of the present invention will be described with reference to the accompanying drawings.

1 is a half sectional front sectional view of an inverted front fork according to the present invention, FIG. 2 is an enlarged detailed view of a portion A in FIG. 1, FIG. 3 is a plan view of the inverted front fork, and FIG. Fig. 1
FIG. 5 is a side view of the motorcycle equipped with the inverted front fork. First, the schematic structure of the motorcycle 1 shown in FIG. 5 will be described.

In FIG. 5, reference numeral 2 denotes a head pipe located at an upper front part of the vehicle body, and a steering shaft 31 described later is inserted through the head pipe 2. The steering shaft 31 supports the upper part of the inverted front fork 3 according to the present invention.
A front wheel 4 is rotatably supported at a lower portion of the vehicle.

On the other hand, a main frame 5 extends rearward from the head pipe 2, and an engine 7 is supported on the main frame 5 and a rear arm bracket 6 connected to the rear ends thereof. A fuel tank 8 is arranged above the engine 7, and tandem seats 9 and 10 are arranged behind the fuel tank 8.

A rear arm 11 is provided below the seats 9 and 10 with its front end pivotally attached to the rear arm bracket 6. A rear wheel 12 is rotatably supported at the rear end of the rear arm 11. I have.

Here, the configuration of the inverted front fork 3 will be described in detail with reference to FIGS. 1 to 4. FIG.

The inverted type front fork 3 has a pair of left and right outer tubes 13, 13, which are upper and lower connecting members 1.
In this embodiment, the outer tubes 13, 13 and the connecting members 14, 15 are integrally formed by aluminum casting.

In each of the outer tubes 13, an inner tube 16 is vertically slidably fitted via upper and lower bearings 17, 17 (see FIG. 2) fitted to the inner periphery of the outer tube 13 from below. In addition, a damper 18 is provided in the outer tube 13 and the inner tube 16. still,
The inner tube of the outer tube 13 has a concave portion 13a as shown in the figure.
Is formed, and lubricating grease is sealed in the recess 13a.

The damper 18 is composed of a cylinder 19 and a rod 20 extending downward from the cylinder 10.The upper end of the cylinder 19 is connected to a cap 21 screwed to the upper end of the outer tube 13 with bolts 22. The lower end of the rod 20 is connected to a cap 23 screwed to the lower end of the inner tube 16 by a nut 24. A cushion spring 25 is interposed between the cylinder 19 and the rod 20.
Inside 19, oil is sealed, and a piston, a valve, and a flow path (all not shown) for generating a damping force are provided. In FIG. 1, reference numeral 26 denotes a seal ring, 27 denotes a bump stopper for preventing bottoming, 28 denotes an axle bracket for supporting the front wheel 4 (see FIG. 5), and 43 denotes a nut.

By the way, as shown in FIG. 3, an assembling relief 14a is formed at the center of the upper front connecting member 14, and the front fork 3 is assembled to the vehicle body without interfering with the head pipe 2 by the relief 14a. be able to. The bosses 14b, 1 are provided on both sides of the escape 14a of the connecting member 14.
4b, and a crown member 29 substantially constituting a handle crown is formed on these boss portions 14b, 14b by bolts 30 which are inserted into elongated holes (not shown) which are formed in the vertical direction and are long in the vertical direction. Are bound. The reason why the long hole of the crown member 29 is provided as described above is to absorb an accuracy error at the time of assembly by the long hole.

As shown in FIG. 4, the connecting member 15 at the front lower side is formed with a lightened portion 15a for reducing the weight, and an iron steering shaft is formed at the center of the portion 15a as shown in FIG.
31 is press-fitted. The steering shaft 31 stands vertically upward from the connecting member 15 and penetrates the head pipe 2 and the crown member 29. The upper end of the steering shaft 31 is connected to the crown member 29 by a nut 32 and supported. Have been. The steering shaft 31 is rotatably supported on the head pipe 2 by upper and lower ball bearings 33,33.

Thus, while the motorcycle 1 shown in FIG.
The outer tube moves up and down following the road surface irregularities.
Relative motion occurs between the inner tube 16 and the inner tube 16, and between the cylinder 19 and the rod 20 of the damper 18, and the relative motion causes oil to flow in the cylinder 19. The damping force is generated. And this damping force and cushion spring
25 absorbs and reduces the impact received by the motorcycle 1.

As described above, in the front fork 3 according to the present embodiment, the pair of left and right outer tubes 13 and 13 and the connecting members 14 and 15 are provided.
Are integrally formed by aluminum casting, so that there is no need to join them, and the number of assembly steps and the number of parts can be reduced.

By the way, as shown in FIG. 6, in this embodiment, since each outer tube 13 and the handle stay 50, the lamp stay 51 and the like are integrally formed, the number of parts and the number of assembling steps can be further reduced.

Further, in this embodiment, the outer tubes 13, 13 and the connecting members 14, 15 are integrated instead of connecting the separately processed outer tube and the connecting member as in a conventional inverted front fork. Since the machined part is machined, the working and assembling accuracy (particularly parallelism) is increased, and the operability of the inverted front fork 3 is improved.

Further, since the connecting member 15 does not protrude to the side of the outer tubes 13, 13, the connecting member 15 is
(See FIG. 5), there is no need to provide a recess in the fuel tank 8 to avoid interference with the connecting member 15, and therefore the capacity of the fuel tank 8 can be increased.

By the way, in the present embodiment, since the bearings 17, 17 are fitted on the inner periphery of each outer tube 13 as described above, the inner tube 16 does not slide on the inner peripheral surface of the outer tube 13, so that the surface roughness is reduced. It is not necessary to keep the degree high, and the processing cost of the inner peripheral surface of the outer tube 13 can be reduced.

In this embodiment, the steering shaft 31 was press-fitted into the connecting member 15, but this was inserted into the outer tube 1 during casting.
It may be cast together with 3,13 etc. However, in this case, it is necessary to prevent the rotation of the steering shaft 31 and prevent the steering shaft 31 from slipping upward.

Here, FIGS. 7 and 8 show a modification of the above embodiment.

FIG. 7 is a partial front sectional view of the inverted front fork, and FIG. 8 is a partial plan view of the inverted fork. In these figures, the same elements as those in the above embodiment are denoted by the same reference numerals.

Thus, in this embodiment, after the steering shaft 31 is passed through the head pipe 2,
The upper end of the steering shaft 31 penetrates the crown member 29 and is fastened to the crown member 29 by bolts 35. The crown member 29
Are fastened to the upper part of the connecting member 14 by bolts 36,36.

(Effects of the Invention) As is clear from the above description, according to the present invention, the pair of left and right outer tubes and the connecting member are integrated, so that there is no need to connect both, and the number of assembly steps and the number of parts are reduced. Can be reduced. Since the handle stay is formed integrally with each outer tube, the number of assembly steps and the number of parts can be further reduced.

Also, the present invention does not combine the separately processed outer tube and the connecting member as in a conventional inverted type front fork, but performs machining on an integrated outer tube and a connecting member. As a result, machining and assembling accuracy are increased, and the operability of the inverted front fork is kept high.

Furthermore, in the present invention, since the connecting member does not protrude to the side of the outer tube as in the prior art, interference between the connecting member and the fuel tank in a motorcycle is avoided,
There is no need to provide a recess in the fuel tank to avoid interference with the connecting member, and the capacity of the fuel tank can be increased.

[Brief description of the drawings]

FIG. 1 is a half sectional front view of an inverted front fork for a motorcycle according to the present invention, FIG. 2 is an enlarged detailed view of a portion A in FIG. 1, and FIG. 3 is a plan view of the inverted front fork for the motorcycle. Fig. 4, Fig. 4 is a sectional view taken along the line IV-IV in Fig. 1, Fig. 5 is a side view of the motorcycle provided with the inverted front fork for the motorcycle, and Fig. 6 is an upper portion of the inverted front fork of the motorcycle. FIG. 7 is a partial front sectional view of an inverted front fork for a motorcycle showing a modification of the embodiment of the present invention, and FIG. 8 is a partial plan view of the same. 1 ... motorcycle, 2 ... head pipe, 3 ... inverted front fork for motorcycle, 13 ... outer tube, 14, 15 ... connecting member, 16 ... inner tube, 29
…… Crown member, 31 …… Steering shaft, 50…
... handle stays.

Claims (1)

(57) [Claims] An inner tube is slidably fitted to each of a pair of left and right outer tubes from below, and
In an inverted front fork for a motorcycle comprising outer tubes connected by upper and lower connecting members, the outer tube and upper and lower connecting members are integrally formed by casting, and a lower portion of a steering shaft inserted into a head pipe is provided at a lower portion. It is fixed to the connecting member, and the upper screw part of the steering shaft is fastened to the crown member with a nut,
An inverted front fork for a motorcycle, wherein the crown member is fixed to the upper connecting member with bolts, and a handle stay is formed integrally with each outer tube.