JP2688916B2 - Motorcycle body frame - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle body frame of a motorcycle, and more specifically, to a bracket of a rear arm bracket that directly pivotally supports a rear arm while the main frame is made of sheet metal. The present invention relates to a cast body.

(Prior Art) A body frame as described above is disclosed in, for example, JP-A-60-
There is one disclosed in Japanese Patent No. 113787.

According to this structure, the body frame has a pair of left and right main frames extending rearward and downward from the steering shaft tube, and each main frame is made of sheet metal. A rear arm bracket extends downward from the rear end of each main frame. The bracket main body that constitutes the outer surface side of the rear arm bracket in the vehicle width direction is made of highly rigid cast because it directly pivotally supports the rear arm with a large load. Further, the inner surface side of the rear arm bracket is constituted by a bracket plate made of sheet metal. Further, the bracket main bodies of the left and right rear arm brackets are connected by a cross tube.

(Problems to be solved by the invention) By the way, in order to give a sporty appearance to a motorcycle body, the main frame and the rear arm bracket should be as uniform as possible in appearance, and continuity between them should be maintained. It is desirable to have

However, in the above-described conventional configuration, 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 producing a sporty appearance on the vehicle body as described above.

Further, in the above conventional configuration, since the bracket main body of each rear arm bracket is located on the outer side in the vehicle width direction, the distance between the two bracket main bodies is longer than that on the inner side. Become. Therefore, the length of the cross tube connecting the left and right bracket bodies is correspondingly increased, and accordingly, the weight of the vehicle body is increased.

(Object of the Invention) The present invention has been made by paying attention to the above circumstances, and aims to improve the appearance by making the body of a motorcycle look sporty, and to reduce the weight of the body. To aim.

(Structure of the Invention) A feature of the present invention for achieving the above-mentioned object is that the bracket main body of the rear arm bracket is made of cast metal, and the sheet metal is formed at least at a position on the outer side in the vehicle width direction of the rear arm bracket. It is the extension of the outer plate of the main frame formed from bracket braces.

(Operation) The operation of the above configuration is as follows.

The outer plate 37 of the main frame 35 and the bracket plate 55 of the rear arm bracket 39 formed by extending the outer plate 37 are both made of sheet metal, and therefore the main frame 35 and the rear arm bracket 39 are uniform in appearance. And both of them can have continuity.

Further, the bracket plate 55 made of sheet metal is located on the outer surface side of each rear arm bracket 39, in other words, the bracket body 40 is located on the inner surface side.
Therefore, the distance between the left and right bracket bodies 40, 40 is shortened, and the cross tube connecting them is correspondingly reduced.
44, 45 can be shortened to reduce the weight of the vehicle body.

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

In FIG. 2, 1 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 body frame 2 so as to be steerable. The front fork 3 supports a front wheel 4 at a lower end thereof, and supports a handle 5 at an upper end thereof.

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 the rear arm 8 supports a rear wheel 9 at its swing end. Further, a shock absorber 10 is interposed between the rear portion of the vehicle body frame 2 and the rear arm 8 via a link mechanism 11, and the shock absorber 10 is directed toward the vehicle body frame 2 side toward the rear wheel 9 and the rear arm 8. The shock that is about to be transmitted from the traveling road surface 13 via the is absorbed.

15 is an engine, which is a 4-cycle 4-cylinder engine. The engine 15 is supported on the vehicle body frame 2 by fastening bolts 16. A carburetor 17 is connected to an intake port of the engine 15, and an air cleaner 18 is connected to the carburetor 17. Also, 19 is a fuel tank,
The fuel tank 19 and the air cleaner 18 are covered by a cover body 20.
It is covered by. 21 is a canister.

The front end of the front exhaust pipe 23 is connected to the exhaust port of each cylinder in the engine 15, and each front exhaust pipe 23
The rear end of 23 extends under the engine 15 and extends rearward. The rear end of each of the front exhaust pipes 23 is collected by a collecting pipe 24, and the inside of the collecting pipe 24 serves as an expansion chamber. Further, a rear exhaust pipe 25 extends obliquely rearward and upward from the collecting pipe 24, and a muffler 26 is connected to a rear end of the rear exhaust pipe 25. In this case, the rear exhaust pipe 25 and the 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. The exhaust control device 27 adjusts the opening degree of the exhaust passage from the front exhaust pipe 23 to the collecting pipe 24 according to the rotation speed of the engine 15, and effectively uses the exhaust pressure wave to improve the charging efficiency of the engine 15. I try to raise it.

The engine 15 is provided with a drive chain wheel 29, while the rear wheel 9 is provided with a driven chain wheel 30.
A transmission chain 31 is wound around 9,30. Other, 32
Is a sheet.

Fuel is supplied from the fuel tank 19 to the carburetor 17, and the engine 15 passes through the air cleaner 18 and the carburetor 17.
When the outside air is drawn into the engine 15, the engine 15 can be operated. Then, by transmitting the power to the rear wheels 9 via the transmission chain 31 and the like, the motorcycle 1 can be run.

1 to 9, the body frame 2 has a steering shaft tube 34 for supporting the front form 3 at a front end thereof.
have. Also, a pair of left and right main frames 35, 35 extends 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 facing each other in the vehicle width direction. In this case, in particular, as shown in FIG. 5, both the plates 36 and 37 are welded to each other with a U-shaped cross section, 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. The rear arm bracket 39 is for supporting the rear arm 8, and each bracket body 40 is made of aluminum alloy by casting, and between the inner wall 40a and the outer wall 40b facing each other in the vehicle width direction of the bracket body 40. A cavity is formed, that is, the bracket body 40 is a hollow casting.

On the inner surface of each bracket body 40, a pair of upper and lower recesses 4
2, 43 are formed, of which each end of the upper cross tube 44 is fitted and welded in the upper recess 42, and each end of the lower cross tube 45 is fitted and welded in the lower recess 43. That is, the two cross tubes 44 and 45 are the left and right bracket main bodies 4
0, 40 are firmly connected. In this case, both the cross tubes 44 and 45 are made of aluminum alloy by casting.
Further, each bracket body 40 between the upper and lower cross tubes 44, 45 is formed with a pivot hole 46 extending over the inner wall 40a and the outer wall 40b thereof, and the rear arm 8 is pivotally supported in the pivot hole 46. The pivot shaft 7 is supported.

1 to 3, the shock absorber 10 is composed of a telescopic cylinder-shaped damper 48 and a spring 49 for urging the damper 48 in a direction to extend the damper 48, and the upper end of the damper 48 has a first pivotal support. It is pivotally supported by the pin 50 on the upper cross tube 44.

On the other hand, the link mechanism 11 includes the lower cross tube 45.
Has a main link 52 pivotally supported up and down, and a pair of left and right connecting links 53, 53 connecting the middle portion of the main link 52 and the rear arm 8 are provided. The lower end of the damper 48 is pivotally supported at the moving end.

Then, in the link mechanism 11, the rear wheel 9 receives an impact from the traveling road surface 13 while the motorcycle 1 is traveling,
When the rear arm 8 rotates upward, the contraction amount of the damper 48 increases non-linearly as the rear arm 8 rotates upward, thereby improving the followability of the rear wheel 9 to the traveling road surface 13.

According to FIGS. 1 to 8, the above-mentioned rear arm bracket
39 will be described in more detail.

A step surface 54 is formed on the upper end of the inner wall 40a of the bracket body 40.
Is formed, and the lower end of the inner plate 36 of the main frame 35 is welded to the step surface 54. On the other hand, the outer plate 37 of the main frame 35 formed by the metal plate bracket plate 55 is extended to a position located above the outer surface side of each rear arm bracket 39 in the vehicle width direction, and the lower end of the bracket plate 55 is It is welded to the step surface 56 formed on the upper end of the outer wall 40b of the bracket body 40.

In the above case, since the bracket body 40 directly receives the load from the rear arm 8 side, as described above, the bracket body 40 is made of casting which is heavy but has high rigidity. On the other hand, the portion of the rear arm bracket 39 which is not directly subjected to the load from the rear arm 8 side is constituted by the bracket plate 55 made of a relatively light metal plate as described above, that is, by using such a bracket plate 55, the rear arm The weight of the bracket 39 is reduced. Since the bracket plate 55 is formed by extending the outer plate 37 as described above, the main frame 35 and the rear arm bracket 39 are uniform in appearance.

Moreover, since each of the bracket main bodies 40 is located on the inner surface side of the rear arm bracket 39, the distance between the left and right bracket main bodies 40, 40 is reduced. Therefore,
Therefore, the cross tubes 44, 45 that connect them are connected.
Is shortened so that the weight of the car body is lighter.

Furthermore, according to the above configuration, since the joint between the inner plate 36 and the inner wall 40a and the joint between the outer plate 37 and the outer wall 40b are vertically displaced, it is considered that the strength of these joints decreases. However, this reduction in strength is prevented from being concentrated in one place.

In FIG. 1, FIG. 2, FIG. 8 and FIG. 9, the lower cross tube 45 is bent in a stepwise manner to the upper right, and the right end of the lower cross tube 45 is more than the left end thereof. The lower end of the rear arm bracket 39 located on the upper side and on the right side of the rear arm bracket 39 is short. The rear exhaust pipe 25 is located below the right end of the lower cross tube 45 and as close to the link mechanism 11 as possible. In other words, this rear exhaust pipe 25
Even if is provided on the right side of the vehicle body, the left and right bank angles of the motorcycle 1 are made as uniform 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 some extent. Therefore, the cushion stroke of the shock absorber 10 is extended and the center of gravity of the vehicle body is lowered by lowering the position of the main link 52 as much as possible.

Further, the lower end 58 of the right end of the lower cross tube 45 is a rearwardly inclined surface so as to match the inclination of the rear exhaust pipe 25, and the upper surface of the left end of the upper and lower cross tubes 45 is the same.
Reference numeral 59 designates a rearwardly downward inclined surface so as to match the inclination when the transmission chain 31 is bent as shown by the phantom line in FIG. That is, the lower cross tube 45 is rationally formed so that no unnecessary space is created between the rear exhaust pipe 25 or the transmission chain 31 and the lower cross tube 45.

2 to 4, and 10, the seat bracket 6 is provided at the upper end of the inner wall 40a of each bracket body 40.
1 is integrally molded. Each seat bracket 61 projects rearward and upward, and a front end of a seat rail 62 that supports the seat 32 is screwed to a projecting end of the seat bracket 61. In addition, the same as above seat bracket 61
A reinforcing member 63 is provided between the base of the seat bracket 62 and the rear portion of the seat rate 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 by a cross member 64, and the fuel tank 19 and the cover body are provided on the cross member 64 via an elastic cushioning material 65.
Twenty rears are supported.

FIG. 11 shows another embodiment. According to the figure, the outer surface side of the rear arm bracket 39 is entirely formed by a bracket plate 55 made of sheet metal. Other configurations are the same as those of the above embodiment.

(Effect of the Invention) According to the present invention, since the outer plate of the main frame formed of the bracket plate made of sheet metal is extended to at least a portion located on the outer surface side of the rear arm bracket, the main frame and the rear arm bracket are externally visible. It can be as uniform as possible. In other words, it is possible to give continuity between the two and to give a sporty appearance to the vehicle body of the motorcycle, thus improving the appearance.

Also, as a result of providing the bracket plate on the outer surface side of each rear arm bracket, since the bracket body is located on the inner surface side, the cross tube connecting the left and right bracket bodies can be shortened, thus reducing the weight of the vehicle body. You can

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, and FIG.
FIG. 2 is an overall side view of the motorcycle, and FIG.
FIG. 4 is a partially enlarged view of FIG. 2, FIG. 4 is a sectional view taken along the line IV-IV of FIG. 1, FIG. 5 is a sectional view taken along the line VV of FIG.
FIG. 7 is a sectional view taken along the line VI-VI of FIG. 3 above, FIG. 7 is a sectional view taken along the line VII-VII of FIG. 3 above, and FIG.
VIII line sectional view, FIG. 9 is a perspective view of the lower cross tube, FIG. 10 is a sectional view taken along line XX of FIG. 3, and FIG. 11 is a part of FIG. 1 showing another embodiment. It is a figure equivalent to. 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, 45 …… Lower cross tube, 55 …… Bracket plate.

Claims (1)

(57) [Claims] 1. A pair of left and right main frames extending rearward and downward from a steering shaft tube are provided, and each of the main frames is formed by inner and outer plates made of sheet metal facing each other in the vehicle width direction. A rear arm bracket extending downward from the rear end of the main frame is provided, the bracket main body of this rear arm bracket that directly pivotally supports the rear arm is made of casting, and the bracket main bodies of the left and right rear arm brackets are connected by a cross tube. A vehicle body frame for a motorcycle, wherein the outer plate of a main frame formed of a bracket plate made of sheet metal is extended to at least a portion of the vehicle body frame of the above-mentioned rear arm bracket on the outer side in the vehicle width direction.