JPH10203461A - Body frame structure for two wheeler and front fork mounting structure in car body frame - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a body frame of a two wheeler by a single steel pipe, and on the body frame, mount an accessory part of front fork, step, rear fork, etc., without using a welding bracket. SOLUTION: A car body frame 2, comprising a head tube part 2h, down tube part 2d extended to tilt with a rear down from a lower end thereof, bottom tube part 2b extended almost horizontally rearward from a lower end thereof, and a rear tube part 2r extended to tilt with a rear up from a rear end thereof, is formed by bending a single steel pipe. In a periphery of the head tube part 2h, a support boss of a front fork 4 is turnably fitted, in the bottom tube part 2b and the rear tube part 2r, so as to interpose these parts, a pair of mutually bolt connected interposition members are provided, in a bolt connection part of these interposition members, so as to mount a step and a rear fork 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a body frame structure of a motorcycle such as a bicycle and a motorcycle, and a structure for mounting a front fork to the body frame.

[0002]

2. Description of the Related Art In a conventional motorcycle body frame structure, a main pipe or other frame body supports a head pipe for supporting a steering stem of a front fork on an inner peripheral surface, a step bracket for supporting a step, and a rear fork. It is constructed by welding a rear fork bracket and the like (see Japanese Patent Application Laid-Open No. 56-50650).

[0003]

In such a frame structure of a motorcycle, welding of the head pipe and various brackets to the frame body is indispensable. Therefore, not only the welding process but also the prevention of the welded portion at the time of its manufacture. It has to go through a rusting process, which requires a lot of trouble in production, and it is difficult to reduce the cost.

The present invention has been made in view of the above circumstances, and provides a vehicle body frame structure which can be formed from a single steel pipe without relying on welding, thereby contributing to cost reduction. It is another object of the present invention to provide a front fork mounting structure to a vehicle body frame, in which a front fork can be easily mounted on the vehicle body frame.

[0005]

In order to achieve the above object, the present invention provides a head tube portion for supporting a front fork, a down tube portion which extends from the lower end of the head portion and is inclined downward and rearward. A bottom tube portion extending substantially horizontally rearward from the lower end of the down tube portion and supporting the step, and a rear tube portion extending inclined rearward and upward from the rear end of the bottom tube portion and supporting a rear fork and a saddle. The first feature is that a body frame having no welded portion is formed by bending a single steel pipe.

According to this feature, since the body frame having no welded portion is formed by a single steel pipe, there is no need to weld a head pipe for supporting a front fork or a mounting bracket for a step, a rear fork or the like. .

According to the present invention, in addition to the above features, the vehicle body frame is provided with a pair of holding members which are bolted to each other so as to hold the frame, and a step, a rear fork, etc. The second feature is that the accessory parts are mounted.

According to this feature, the accessory can be easily and reliably attached to the body frame without welding.

Further, according to the present invention, in addition to the first or second feature, the upper end of the rear tube is bent substantially horizontally,
A third feature is that it is formed on a saddle body covered with a saddle cushion.

According to this feature, the structure can be simplified and the cost can be reduced by integrating the vehicle body frame with the saddle body.

Still further, according to the present invention, a head tube extending continuously upward from the upper end of a down tube portion of a vehicle body frame is integrally formed, and a support boss formed on a front fork is formed on an outer periphery of the head tube portion. The fourth feature is that the is rotatably fitted and supported.

According to this feature, the front fork can be easily attached to the outer periphery of the head tube portion.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.

FIG. 1 to FIG. 11 show a first embodiment in which the present invention is applied to a motorcycle with a motor. First, FIGS. 1 and 6
, A body frame 2 of the motorcycle 1 with a motor is provided with a head tube portion 2h which is disposed to be inclined forward and downward,
A down tube portion 2d that extends obliquely downward from the lower end of the head tube portion 2h, a bottom tube portion 2b that extends substantially horizontally rearward from the lower end of the down tube portion 2d, and a rear end of the bottom tube portion 2b It has a substantially U-shape without a welded portion, comprising a rear tube portion 2r extending upward and inclined, and is formed by bending a single steel pipe in such a manner. A front fork 4 supporting the front wheel 3f is provided on the head tube 2h, a step 5 is provided on the bottom tube 2b, and a power unit 6 supporting and driving the rear wheel 3r is provided below the rear tube 2r.
And a cushion 7 that supports the power unit 6 in a cushioning manner are attached as follows. The support post 8a of the saddle 8 is inserted into the upper end of the rear tube 2r and clamped.

First, a structure for mounting the front fork 4 and its head tube 2h will be described with reference to FIGS. The front fork 4 includes a pair of left and right fork legs 11 fixedly provided on both sides of the support boss 10 and extending downward substantially in parallel with the support boss 10. Each of the fork legs 11 has a cylindrical leg base 12. And an upper pipe 13 fitted to the lower end thereof, a lower pipe 14 slidably fitted and connected thereto from below, and a lower pipe 14 interposed between the leg base 12 and the lower pipe 14 in the upper pipe 13. The coil spring 15 is configured to be telescopic. Brackets 16 are welded to the front surfaces of the lower ends of the left and right lower pipes 14, respectively, whereby the front wheels 3f are pivotally supported. Support boss 10
The left and right leg bases 12 are integrally formed by casting.

The support boss 10 is connected to the head tube 2
h is rotatably fitted to the outer periphery of the pair h via a pair of upper and lower angular contact bearings 17a and 17b. At this time, the outer races of the angular contact bearings 17a, 17b are fitted to bearing housings 18a, 18b formed on the inner periphery of both upper and lower ends of the support boss 10. In addition, the lower angular contact bearing 17b
Is supported by an upwardly directed annular step portion 19 formed at the boundary between the head tube portion 2h and the down tube portion 2d, and the inner race of the upper angular contact bearing 17a is provided at the outer periphery of the upper end portion of the head tube portion 2h. Is fixed by a ring nut 20 screwed into the nut. The ring nut 20 is provided with a dust cover 21 that covers the upper end of the support boss 10 together with the upper angular contact bearing 17a.

In this manner, the front fork 4 is steerably supported by the head tube 2h connected to the down tube 2d. Therefore, it is not necessary to employ a frame structure in which a head pipe for supporting the steering stem of the front fork on the inner peripheral surface is welded to the down tube portion as in the related art, which can contribute to simplification of the structure and the manufacturing process.

A steering bar handle 23 is mounted on the front surface of the support boss 10. That is, a pair of left and right handle mounting seats 24 are integrally formed on the front surface of the support boss 10, and a pair of left and right caps 25 which are bolted to these.
Thus, the central portion of the bar handle 23 is sandwiched. Thus,
By rotating the bar handle 23 right and left, the front wheel 3 f can be turned left and right via the front fork 4.

Referring to FIGS. 6 and 7, the bottom tube 2
The mounting structure of Step 5 to b will be described. A pair of left and right bosses 26 arranged coaxially are press-formed on the bottom tube portion 2b. A pair of left and right holding members 28 having bosses 27 arranged coaxially outside these bosses 26 and fitted on the outer surface of one half of the rear tube 2r and the other half of the rear tube 2r.
Are disposed, and the mounting bosses 5a of the left and right steps 5 are coaxially disposed on both outer sides of the boss 27. Then, these mounting bosses 5a and two pairs of bosses 26 and 27 inside thereof are provided.
By screwing and tightening a nut 30 to the tip of a connecting bolt 29 inserted through the bottom tube portion 2b, the two holding members 28 are fixed to the bottom tube portion 2b so as to be held therebetween. Is fixed. Thus, the step 5 can be firmly attached to the bottom tube portion 2b without using a welding bracket.

Referring to FIGS. 6 and 8, the rear tube portion 2r
The structure for attaching the power unit 6 to the power unit will be described. A pair of left and right bosses 26 are press-formed on the rear tube portion 2r in the same manner as in the mounting structure of Step 5 described above. A pair of left and right holding members 28 having coaxially arranged bosses 27 outside of the bosses 26 and fitted to the outer periphery of one half of the rear tube portion 2r and the other half of the rear tube portion 2r are arranged.
These holding members 28 are the same as those used in the mounting structure of step 5 described above. A pair of right and left bosses 32 of a rear fork 31 extending from the power unit 6 are coaxially arranged on both outer sides of the boss 2 of the holding member 28.
On the inner peripheral surface of these bosses 32, rubber elastic bushes 3 are provided.
An outer ring 34 baked on the outer periphery of the elastic bush 3 is press-fitted. A nut is attached to the tip of an inner ring 35 baked on the inner periphery of the elastic bush 34 and a connecting bolt 36 inserted into two pairs of bosses 26 and 27 on the inner side. By screwing and tightening 37, both holding members 28 are fixed to the rear tube portion 2r so as to hold them, and the outer ring 34 is fixed to both holding members 28. The rear fork 31 can swing around the connection bolt 36 due to the torsional deformation of the elastic bush 33. In this manner, the power unit 6 can be supported so as to be able to swing up and down without providing the welding bracket on the rear tube portion 2r.

6 and 9, the rear tube portion 2r
The structure for attaching the cushion 7 to the vehicle will be described. A pair of left and right holding members 40 are arranged so as to be fitted on the outer peripheral surface of one half of the rear tube portion 2r and the outer surface of the other half of the rear tube. Bosses 41 opposing each other with a small gap at their upper ends and bosses 42 opposing each other with a large gap at their lower ends are integrally formed on both holding members 40. The upper mounting ring 7a of the cushion 7 is disposed at the bottom. An elastic bush 43 made of rubber is provided on the inner periphery of the upper mounting ring 7a, and an inner ring 4 is provided on the inner periphery of the bush 43.
4 are respectively baked, and first, both lower bosses 4
The two members 2 and the inner ring 44 are fixed to each other by screwing and tightening a nut 48 to the tip of a connecting bolt 47 inserted therethrough, and then both upper bosses 41 are inserted therethrough. The nut 46 is screwed onto the tip of the connecting bolt 45 and tightened to be fixed to each other. In this way, the two holding members 40 are fixed to the rear tube portion 2r so as to hold them, and the upper mounting ring 7a of the cushion 7 is elastically supported by the two holding members 40. Therefore, the need for a welding bracket for its support is eliminated.

Next, the power unit 6 and the rear wheel 3r will be described with reference to FIGS. The power unit 6 includes an engine 50 having a crankshaft 51 disposed in the left-right direction of the vehicle body and a crankcase 52 of the engine 50.
And a transmission 54 housed in a transmission case 53 integrally formed. Input shaft 55 of transmission 54
The output shaft 56 is arranged in parallel with the crankshaft 51.

On the other hand, the rim 57 and the hub 58 of the rear wheel 3r are integrally connected via a bowl-shaped spoke 59 bulging to one side of the rim 57. The power unit 6 is accommodated in the accommodating portion 60 defined, and the hub 58 is spline-fitted to the output shaft 56 and is fixed by a nut 61.

The rear fork 31 extending forward around one side of the rim 57 is formed integrally with the engine body, that is, the cylinder block 62, the cylinder head 63, or the crankcase 52 of the engine 50. Engine 5
0, a kick starter 65 is provided on the opposite side of the output shaft 56. Incidentally, reference numeral 66 in the drawing denotes a fuel tank, and 67 denotes an exhaust muffler.

FIGS. 12 and 13 show a second embodiment of the present invention. In the vehicle body frame 2, the upper end of the rear tube portion 2r is bent substantially horizontally rearward to form a saddle main body 70, and urethane is added thereto. The configuration is the same as that of the previous embodiment except that the saddle 8 is formed by covering the foam-made tubular saddle cushion 71. In the figure, the same reference numerals are given to the portions corresponding to the previous embodiment. The description is omitted.

FIGS. 14 and 15 show a third embodiment of the present invention. In the vehicle body frame 2, the upper end of the rear tube portion 2r is bent right and left in a U-shape to form a saddle body 70. Except for this point, the configuration is the same as that of the above-mentioned second embodiment.
The same reference numerals are given and the description is omitted.

According to the second and third embodiments, the saddle 8 is integrated with the body frame 2 and the saddle body 70.
Can be simplified.

The present invention is not limited to the above embodiments, and various design changes can be made without departing from the gist of the present invention. For example, the front fork 4 can be configured as a monopod to support the front wheel 3f in a cantilever manner. The present invention is also applicable to bicycles.

[0029]

As described above, according to the first aspect of the present invention, a head tube for supporting a front fork,
A down tube portion that inclines backward and downward from the lower end of the head portion; a bottom tube portion that extends substantially horizontally rearward from the lower end of the down tube portion to support a step; A body frame without welds, consisting of a rear fork and a rear tube part that supports the saddle and extends upward, is formed by bending a single steel pipe, so that a head pipe and a step for supporting the front fork, There is no need to weld a mounting bracket such as a rear fork, so that the structure and the manufacturing process can be simplified, and the cost can be reduced.

According to a second feature of the present invention, the vehicle body frame is provided with a pair of holding members which are bolted to each other so as to hold the body frame. Since the accessory parts are attached, the accessory parts can be easily and reliably attached to the body frame without welding.

According to the third feature of the present invention, the upper end of the rear tube is bent substantially horizontally to form the saddle body covered with the saddle cushion, so that the body frame and the saddle body can be integrated. The structure can further simplify the structure and reduce the cost.

According to a fourth feature of the present invention,
A head tube extending continuously upward from the upper end of the down tube portion of the body frame is integrally formed, and a support boss formed on a front fork is rotatably fitted and supported on the outer periphery of the head tube portion. Therefore, the front fork can be easily attached to the outer periphery of the head tube portion.

[Brief description of the drawings]

FIG. 1 is a side view of a motorcycle with a motor according to a first embodiment of the present invention.

FIG. 2 is a view taken in the direction of arrow 2 in FIG. 1;

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2;

FIG. 4 is a sectional view taken along line 4-4 of FIG. 2;

FIG. 5 is a view taken in the direction of arrow 5 in FIG. 2;

FIG. 6 is an enlarged view of part 6 of FIG.

FIG. 7 is a sectional view taken along line 7-7 of FIG. 6;

FIG. 8 is a sectional view taken along line 8-8 in FIG. 6;

FIG. 9 is a sectional view taken along line 9-9 of FIG. 6;

FIG. 10 is a view taken in the direction of arrow 10 in FIG. 6;

FIG. 11 is a sectional view taken along line 11-11 of FIG. 6;

FIG. 12 is a side view similar to FIG. 1, showing a second embodiment of the present invention.

FIG. 13 is a view taken in the direction of arrow 13 in FIG. 12;

FIG. 14 is a side view similar to FIG. 1, showing a third embodiment of the present invention.

FIG. 15 is a view taken in the direction of arrow 15 in FIG. 14;

[Explanation of symbols]

 1 ... two-wheeled vehicle 2 ... body frame 2b ... bottom tube 2d ... down tube 2h ... head tube 2r ... rear tube 4 ... front fork 5 Step 8 Saddle 10 Support boss 28 Nipping member 31 Rear fork 40 Nipping member 70 Saddle body 71 Saddle cushion

Claims (4)

[Claims] 1. A head tube portion (2h) for supporting a front fork (4), and a down tube portion (2h) extending from a lower end of the head portion (2h) to incline rearward and downward.
d), a bottom tube portion (2b) extending substantially horizontally rearward from the lower end of the down tube portion (2d) and supporting the step (5), and rising rearward from the rear end of the bottom tube portion (2b). The rear fork (31) that extends inclining
A body frame structure for a two-wheeled vehicle, wherein a body frame (2) having no weld portion, comprising a rear tube portion (2r) supporting a saddle (8), is formed by bending a single steel pipe. 2. The vehicle body frame (2) according to claim 1, wherein the body frame (2) is provided with a pair of holding members (28, 40) bolted to each other so as to hold the body frame.
A vehicle body frame structure for a motorcycle, wherein accessory parts such as a step (5) and a rear fork (31) are attached to the bolted portions of the holding members (28, 40). 3. The saddle body (70) covered with a saddle cushion (71) according to claim 1 or 2, wherein an upper end of the rear tube (2r) is bent substantially horizontally. A motorcycle frame structure for a motorcycle. 4. A head tube (2h) which extends continuously upward from the upper end of the down tube portion (2d) of the vehicle body frame (2) is formed integrally with the outer periphery of the head tube portion (2h). A front fork mounting structure to a vehicle body frame of a motorcycle, wherein a support boss (10) formed on a front fork (4) is rotatably fitted and supported.