Frame structure for a motorcycle

Field of the invention:

The present invention relates to "Frame structure for a motorcycle" and more particularly to a rear body frame structure of a scooter type motorcycle.

Background of the invention:

In the known conventional frame structure of a scooter type motorcycle is equipped with one main pipe that extends in the longitudinal direction of the chassis under the floor panel on which the rider's feet are placed and that rises in front toward a head pipe, and a pair of left and right rear frames that are arranged in parallel to the left and right under a seat and whose front ends incline forward and downward and are connected to the rear end of the above mentioned main pipe, wherein the seat can be supported on these rear frames. The front ends of the left and right rear frames are connected laterally to the main pipe thru' a bridge bracket and the rear ends of the left and right rear frames are connected. In such scooter type motorcycles in which fuel tank is mounted at the rear end of the rear frame, this type of rear frame structure limits the space available for fuel tank and hence limits the capacity of the fuel tank. Hence, the objective of the present invention is to provide a frame structure for a scooter type motorcycle, which supports fuel tank mounting at the rear end side of the rear frame without any limitation to storage capacity of the fuel tank and without increasing the overall size of the vehicle.

Summary of the invention:

According to an aspect of the present invention there is provided a scooter type motorcycle comprising a frame structure for a scooter, equipped with one main pipe that extends in the longitudinal direction of the chassis under the foot panel on which the rider's feet are placed and that rises in front toward a head pipe, and a pair of left and right rear frames that are arranged in parallel to the left and right under a seat and whose front ends incline forward and downward, and are connected to the rear end of the aforementioned main pipe, allowing the seat to be supported on these rear frames; wherein said rear frame structure for a scooter is characterized by the fact that: The rear ends of the left and right rear tubular frames are flattened and are unconnected and left open so that the fuel tank with higher capacity can be mounted.

In another embodiment, the left and right rear tubular frames are connected through four cross brackets in the vehicle direction; a utility box and a seat are supported by first and second cross brackets, a fuel tank is mounted to the second, third and fourth cross brackets through mounting provisions furnished for mounting fuel tank on the corresponding first, second and third cross brackets.

Further, the said third bridge bracket is furnished with mounting provisions for clamping grab handle and another bracket is mounted at the middle of the said third bridge bracket to support seat lock.

In another embodiment, the fourth bridge bracket is a steel tube bent to form an inverted U shape and metallic brackets are welded on this tubular connection to form various mounting points to mount side panels, fuel tank cover as well as tail lamps.

However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

Brief Description of the Drawings:

The present invention will become more fully understood from the detailed
description given herein below and the accompanying drawings which are given
by way of illustration only, and thus are not limitative of the present invention, and
wherein

FIG. 1 is a left side view of a two wheeled motor vehicle according to a first
embodiment of the present invention.

FIG. 2 is a perspective view of the frame structure according to the present
invention.

FIG. 3 is a top view of the frame structure according to the present invention. Detail Description of the Drawings:

Embodiments of the present invention now be described with reference to the accompanying drawings. In the following description, "front", "rear", "upper", "lower", "right", "left" and "bottom" represent directions viewed from the perspective of the vehicle rider.

First with reference to FIGS 1 to 3, a description will now be given concerning a frame structure according to the first embodiment of the present invention. First the whole structure of the vehicle will be roughly described. A reference number 1 in Fig.1 denotes a front wheel, 2 denotes a front fork, 3 denotes a front fender, 4 denotes a front cover, 5 denotes a leg shield made of resin or metal, 6 denotes a handle bar cover, 7 denotes a headlight, 8 denotes a handle bar ,17 denotes a rear fender and 18 denotes tail lamp.

The center of the body forms a low floor board 9 for functioning as a part for putting feet and a under cowl 10 which is located below the rider's seat and covers at least a part of the engine, The under cowl is made up of metal or resin. The under cowl is hinged to the seat 11. A utility box (or object storage member) 12 opens from the rear end to hinged portion. The utility box 12 is provided under the seat extending longitudinally of a vehicle body and the inside of the utility box has a large capacity so that a large article can be housed. A main frame 14 extended along the center of the body before and behind and made of a metallic pipe and is provided under the floor board 9. A swing type power unit 13 is coupled to the rear end of the main frame 14.

A rear wheel 15 is supported on one side of the rear end of the swing type power
unit 13. The swing type power unit 13 is suspended in the rear of a body frame.
The side covers 16 both on left and right sides, covers the utility box 12 and other
parts of the vehicle, thereby providing a good appearance to the vehicle.

As shown in figure 2, further the rear part of the frame structure comprises a pair
of left and right rear frames (201, 202) that are arranged in parallel to the left and
right under a seat and whose front ends incline forward and downward, and are
connected to the rear end of the aforementioned main frame (or down tube) (14),
allowing the seat to be supported on these rear frames. The rear most end of the
said left and right rear tubular frames are flattened and are left open to
accommodate fuel tank having additional volume.

In another embodiment, the left and right rear tubular frames are connected
through four cross brackets in the vehicle direction; a utility box and a seat are
supported by first (203) and second (204) cross brackets, a fuel tank is mounted
to the second (204), third (205) and fourth (206) cross brackets through mounting
provisions furnished for mounting fuel tank on the corresponding first, second
and third cross brackets.

Further, the said third bridge bracket (205) is furnished with mounting provisions
for clamping grab handle and another bracket is mounted at the middle of the
said third bridge bracket to support seat lock.

In another embodiment, the fourth bridge bracket (206) is a steel tube bent to form an inverted U shape and metallic brackets are welded on this tubular connection to form various mounting points to mount side panels, fuel tank cover as well as tail lamps.

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

We Claim:

1. A frame structure for a motorcycle having fuel tank mounted at the rear
end side of the vehicle comprising:

a head tube;

a down tube extending from head tube to a rearward portion of a vehicle
body; and

at least two rear frame tubes extending rearwardly upward from down
tube,

wherein at least four cross members are provided between the two rear
frame tubes.

2. The frame structure for a motorcycle as claimed in claim 1, wherein the said rear frames ends are preferably made flattened.

3. The frame structure for a motorcycle as claimed in claim 1, wherein the said first and second said cross members supports utility box and seat.

4. The frame structure for a motorcycle as claimed in claim 1, wherein the fuel tank is mounted to said second, third and fourth cross member.

5. The frame structure for a motorcycle as claimed in claim 1, wherein the said third cross member is provided with mounting provisions to clamp grab handle.

6. The frame structure for a motorcycle as claimed in claim 1, wherein the said fourth cross member is preferably of inverted U shape.

7. The frame structure for a motorcycle as claimed in claim 1, wherein the said fourth cross member is provided with metallic brackets to mount side panels, fuel tank cover and tail lamps.

8. The frame structure for a motorcycle as claimed in claim 1, wherein the said third cross member midway is provided with a bracket to support seat lock.