JPH01237276A - Body frame of motorcycle - Google Patents

Abstract

PURPOSE:To reduce weight by forming main frames extending rear downward from a head pipe with a sheet metal, forming rear-arm brackets which extend downward from the rear ends of the main frames by casting, and making the the outer face side upper portion thereof the extension of the outer plate of the sheet-metal frame of the main frame. CONSTITUTION:Each of a pair of main frames 35 which extend rear downward from a head pipe is formed with sheet metal frames consisting of an inner plate 36 and an outer plate 37, while forming rear-arm brackets 39 which extend downward from the rear ends of the main frames 35 by casting. Upper and lower cross tubes 44, 45 and the pivotally supporting shaft 7 of rear arms 8 are provided on the rear-arm brackets 39 to support rear wheels. The inner face sides on the upper portions of the cast rear-arm brackets 39 form the supporting portions of the cross tube 44 while the outer face sides thereof being formed as the extensions of the outer plates 37 of the main frames 35. Thereby, the weight of the cast brackets requiring strength can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to a body frame for a motorcycle, and more specifically, the main frame is made of sheet metal, and a bracket for a rear arm bracket that directly supports a rear arm is provided. It relates to a device whose main body is a cast blade.

(Prior art) For example, in the above-mentioned car body frame, there is a
There is one shown in Japanese Patent No. 113787.

According to this configuration, the vehicle body frame has a pair of left and right main frames extending rearward and downward from the steering shaft tube,
Each main frame is made of sheet metal. Further, a rear arm bracket extends downward from the rear end of each of the main frames.

The bracket body forming the outer surface side of the rear arm bracket in the vehicle width direction is made of a cast blade with high rigidity because it directly supports the rear arm, which is subjected to a large load. Also,
The inner surface of the rear arm bracket is made up of a bracket plate made of sheet metal. Furthermore, the bracket bodies of the left and right rear arm brackets are connected to each other by a cross tube.

(Disadvantage to be Solved by the Invention) Incidentally, in order to give the body of a motorcycle a sporty appearance, the main frame and rear arm bracket should be made as uniform in appearance as possible, and there should be continuity between them. It is desirable to have gender.

However, in the conventional configuration described above, the main frame and the rear arm bracket are made of different materials, so that the two can be clearly distinguished in appearance. Therefore, this is not preferable from the viewpoint of giving the vehicle body a sporty appearance as described above.

In addition, in the above conventional configuration, the bracket bodies of each rear arm bracket are located on the outer side in the vehicle width direction, compared to the fact that they are located on the inner side.
The distance between these two bracket bodies becomes longer. Therefore, the length of the cross tube that connects the left and right bracket bodies becomes longer, which inconveniently increases the weight of the vehicle.

(Object of the Invention) This invention was made in view of the above-mentioned circumstances, and it is an object of the present invention to improve the appearance of a motorcycle by giving it a sporty appearance, and to make the body of the motorcycle lighter. purpose.

(Structure of the Invention) A feature of the present invention for achieving the above object is that the bracket main body of the rear arm bracket is made of cast material, and at least the upper part of the outer surface side in the vehicle width direction of the rear arm bracket is placed behind the outer plate of the main frame. The point is that it is formed by a sheet metal bracket and seat plate that connects to the end.

(for production) The effect of the above configuration is as follows.

The outer plate 37 of the main frame 35 and this outer plate 3
Both the bracket plates 55 of the rear arm bracket 39 connected to the rear end of the rear arm bracket 7 are made of sheet metal, so that the main frame 35 and the rear arm bracket 39 can be made to look similar in appearance, and have continuity between them. Furthermore, each rear arm bracket 39 has a bracket plate 55 made of sheet metal located on its outer surface, in other words, the bracket main body 40 is located on its inner surface. Therefore, the distance between the left and right bracket bodies 40 and 40 is short, so the cross tubes 44 and 45 that connect them can be shortened to reduce the weight of the vehicle body.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 2, l is a motorcycle, 2 is its body frame, and this body frame 2 is a diamond frame. A front fork 3 is supported at the front end of the vehicle body frame 2 so as to be freely steerable.
supports a front wheel 4 at its lower end and a handlebar 5 at its upper end.

A rear arm 8 is pivotally supported at the rear end of the vehicle body frame 2 by a pivot shaft 7 so as to be vertically swingable, and this rear arm 8 supports a rear wheel 9 at its swing end. Further, a shock absorber 10 is interposed between the rear part of the vehicle body frame 2 and the rear arm 8 via a link mechanism 11, and this shock absorber 10 is connected to the rear wheel 9 and the rear arm 8 toward the vehicle body frame 2 side. It buffers the impact that is about to be transmitted from the running road surface 13 via the road surface 13.

I5 is the engine, which is a 4-stroke, 4-cylinder engine. This engine 15 is supported by the vehicle body frame 2 by fastening bolts 16. A carburetor 17 is connected to the intake port of this engine 15.
An air cleaner 18 is connected to the air cleaner 18. Further, 19 is a fuel tank, and this fuel tank 19 and the air cleaner 18 are integrally covered by a cover unit 20.

21 is a canister.

The front end of a front exhaust pipe 23 is connected to the exhaust boat of each cylinder in the engine 15, and the rear end of each front exhaust pipe 23 extends rearward through the lower part of the engine 15. In addition, the rear ends of these front exhaust pipes 23 are gathered together by a collecting pipe 24, and the inside of this collecting pipe 24 is an expansion chamber. A rear exhaust pipe 25 extends, and a muffler 26 is connected to the rear end of the rear exhaust pipe 25. in this case,
The rear exhaust pipe 25 and muffler 26 are located on the right side of the rear wheel 9.

An exhaust control device 27 is interposed between the rear end of the front exhaust pipe 23 and the collecting pipe 24. This exhaust control device 2
7 is the front exhaust pipe 2 according to the rotational speed of the engine 15.
The opening degree of the exhaust passage from 3 to the collecting pipe 24 is adjusted to effectively utilize exhaust pressure waves to increase the filling efficiency of the engine 15.

The engine 15 is provided with a drive chain wheel 29,
On the other hand, the rear wheel 9 is provided with a driven chain wheel 30, and a transmission chain 31 is wound around both chain wheels 29 and 30.

Additionally, 32 is a sheet.

When fuel is supplied from the fuel tank 19 to the carburetor 17 and outside air is taken into the engine 15 through the air cleaner 18 and the carburetor 17, the engine I5 can be operated. Then, by transmitting the power to the rear wheel 9 via the transmission chain 31 or the like, the motorcycle 1 can be driven.

1 to 9, the vehicle body frame 2 has a steering shaft tube 34 supporting the front fork 3 at its front end.
have. Further, a pair of left and right main frames 35, 35 extend rearward and downward from the steering shaft tube 34. Each main frame 35 is formed by inner and outer plates 36 and 37 made of sheet metal that face each other in the vehicle width direction. In this case, especially as shown in FIG.
．． 37 have a U-shaped cross section and are welded to each other, and the main frame 35 has a box-shaped cross section.

A rear arm bracket 39 extends downward from the rear end of each main frame 35. This rear arm bracket 39 is for supporting the rear arm 8,
Each bracket body 40 is made of cast aluminum alloy, and an inner wall 40a of the bracket body 40 faces in the vehicle width direction.
A hollow portion is formed between the bracket main body 40 and the outer wall 40b, that is, the bracket main body 40 is a hollow casting.

The inner surface of each bracket body 40 has a pair of upper and lower recesses 4.
2.43 is formed, of which each end of the upper cross tube 44 is fitted and welded into the upper recess 42, and the lower recess 4 is welded.
3 into which each end of a lower cross tube 45 is fitted and welded. That is, both cross tubes 44, 45 firmly connect the left and right bracket bodies 40, 40. Both of the cross tubes 44 and 45 are made of cast aluminum alloy. Each bracket body 4 between the upper and lower cross tubes 44 and 45 is
0 has a pivot hole 46 formed across its inner wall 40a and outer wall 40b, and the rear arm 8 is inserted into this pivot hole 46.
The pivot shaft 7 that pivots is supported.

In FIGS. 1 to 3, the shock absorber IO is composed of a telescopic cylindrical damper 48 and a spring 49 that biases the damper 48 in the direction of extension, and the upper end of the damper 48 is attached to a first pivot. It is pivoted to the upper cross tube 44 by a bin 50.

On the other hand, the link mechanism 11 is connected to the lower cross tube 4.
A pair of left and right connecting links 53 and 53 are provided to connect the middle part of this main link 52 and the rear arm 8. The lower end of the damper 48 is pivotally supported at the rotating end.

Therefore, when the rear wheel 9 receives an impact from the road surface 13 while the motorcycle l is running and the rear arm 8 rotates upward, the link mechanism 11 moves the damper 48 as the rear arm 8 rotates upward. The amount of reduction is increased non-linearly, thereby improving the followability of the rear wheels 9 with respect to the running road surface 13.

According to FIGS. 1 to 8, the above rear arm bracket 3
9 will be explained in more detail.

A stepped surface 54 is formed at the upper end of the inner wall 40a of the bracket main body 40, and the main frame 3 is attached to this stepped surface 54.
The lower end of the inner plate 36 of No. 5 is welded. On the other hand, the upper part of the outer surface in the vehicle width direction of each rear arm bracket 39 is formed by a sheet metal bracket plate 55 that is integrally connected to the lower end of the outer plate 37 of the main frame 35, and the lower end of this bracket plate 55 is connected to the outer wall of the bracket main body 40. It is welded to a stepped surface 56 formed on the upper end of 40b.

In the above case, since the bracket body 40 directly receives the load from the rear arm 8 side, the bracket body 40 is made of a cast material which is heavy but has high rigidity, as described above. On the other hand, the portion of the rear arm bracket 39 that does not directly receive the load from the rear arm 8I11 is constituted by the relatively light bracket plate 55 made of sheet metal, as described above.In other words, by using such a bracket plate 55, the rear arm bracket 39 is being made lighter. And the bracket plate 55
As described above, since the main frame 35 and the rear arm bracket 39 are provided so as to be continuous with the rear end of the outer plate 37, the main frame 35 and the rear arm bracket 39 have a similar appearance.

Moreover, since each of the bracket bodies 40 is located on the inner side of the rear arm bracket 39, the distance between the left and right bracket bodies 40, 40 is shortened. Therefore, the cross tubes 44 and 45 connecting these parts are shortened to reduce the weight of the vehicle body.

Furthermore, according to the above configuration, the inner plate 36 and the inner wall 40a
and the joint between the outer plate 37 and the outer wall 40b are vertically offset, so even if there is a decrease in strength at each of these joints, this decrease in strength will not be concentrated in one place. Prevented.

In FIGS. 1, 2, 8, right, and 9, the lower cross tube 45 is bent stepwise upward to the right, and the right end of the lower cross tube 45 is closer to the left end. The lower end of the rear arm bracket 39 on the right side is also located above, and accordingly, the lower end of the right rear arm bracket 39 is formed short. The rear exhaust pipe 25 is located below the right end of the lower cross tube 45 and as close as possible to the link mechanism 11. In other words, even when the rear exhaust pipe 25 is provided on the right side of the vehicle body, the left and right bank angles of the motorcycle l are made to be as equal as possible.

Further, in the above case, since the link mechanism 11 is located at the center in the vehicle width direction, the bank angle is not limited even if the main link 52 is lowered to a certain extent. By lowering it as much as possible, the cushion stroke of the shock absorber 10 is lengthened and the center of gravity of the vehicle body is lowered.

Further, the lower right end surface 58 of the lower cross tube 45 is formed as a rear upwardly sloped surface to match the slope of the rear exhaust pipe 25, and the left end upper surface 59 of the lower cross tube 45 is formed so that the transmission chain 31 As shown by the imaginary line in Figure 1, the sloped surface of the rear end is designed to match the slope when bent. That is, the lower cross tube 45 is rationally shaped so that no wasted space is created between the rear exhaust pipe 25, the transmission chain 31, and the lower cross tube 45.

In FIGS. 2 to 4 and 10, a seat bracket 61 is integrally molded on the upper end of the inner wall 40a of each of the bracket main bodies 40. As shown in FIGS.

Each seat bracket 61 protrudes rearward and upward, and the protruding end of each seat bracket 61 has the seat 3
The front end of the seat rail 62 that supports 2 is screwed. Further, a reinforcing member 63 is installed at the base of the seat bracket 61 and the rear part of the seat rail 62, and the seat rail 62 is firmly supported by the seat bracket 61.

Further, the protruding ends of the left and right seat brackets 61 are connected to each other by a cross member 64, and the rear portions of the fuel tank 19 and the cover unit 20 are supported on the cross member 64 via an elastic cushioning material 65.

FIG. 11 shows another embodiment, and according to figure 0, the entire outer surface of the rear arm bracket 39 is formed by a bracket plate 55 made of sheet metal. The other configurations are the same as those in the previous embodiment.

Although the above is based on the illustrated example, the outer plate 37 of the main frame 35 and the bracket plate 55 may be separate bodies.

(Effects of the Invention) According to the present invention, at least the upper part of the outer surface of the rear arm bracket is formed by a sheet metal bracket plate connected to the rear end of the outer plate of the main frame, so that the main frame and rear arm bracket can be made as uniform in appearance as possible. can do.

In other words, by providing continuity between these two, it is possible to give the body of the motorcycle a sporty appearance, thereby achieving improved appearance.

In addition, as a result of providing the bracket plate on the outer surface of each rear arm bracket, the bracket body is located on the inner side, so the cross tube connecting the left and right bracket bodies can be shortened, thereby reducing the weight of the vehicle body. Can be done.

[Brief explanation of the drawing]

The figures show an embodiment of the invention, and Figure 1 is 1-1 in Figure 3.
41i1 arrow sectional view, Fig. 2 is an overall side view of the motorcycle, Fig. 3 is a partially enlarged view of Fig. 2, and Fig. 4 is IV of Fig. 1.
- IV line arrow sectional view, Figure 5 is the v-vili of Figure 3.
6 is a sectional view taken along the line Vl-Vt* in FIG. 3, FIG. 7 is a sectional view taken along the line ■-■ in FIG. 9 is a perspective view of the lower cross tube, 1O is a sectional view taken along the line x-X of FIG. 3, and FIG. 11 is 1 showing another embodiment. It is a figure corresponding to a part of. 1. Motorcycle, 2. Body frame, 34. Steering shaft tube, 35. Main frame, 36. Inner plate, 37
・・Outer plate, 39 ・・Rear arm bracket, 40
・・Bracket body, 44・・Upper cross tube, 4
5. Lower cross tube, 55. Bracket plate. 40b 56

Claims (1)

[Claims] 1. A pair of left and right main frames are provided that extend rearward and downward from the steering shaft tube, and each main frame is formed with inner and outer plates made of sheet metal that face each other in the vehicle width direction. A rear arm bracket is provided that extends downward from the rear end, and the bracket body of the rear arm bracket that directly supports the rear arm is made of cast material,
In a motorcycle body frame in which the bracket bodies of the left and right rear arm brackets are connected to each other by a cross tube, at least the upper part of the outer surface side in the vehicle width direction of each rear arm bracket is connected to the rear end of the outer plate of the main frame by a sheet metal bracket plate. Molded motorcycle body frame.