Frame structure for a scooter type motorcycle

Field of the invention:

The present invention relates to a scooter type motorcycle, specifically to a body frame structure of a scooter type motorcycle.

Background of the invention:

Known conventional frame structure of scooter 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 of closed C section. Since the width of the bracket is wider in the longitudinal direction to achieve the required rigidity, the swing power unit is moved backwards making the wheel base longer which increases overall size of the vehicle. Also since the height of the bracket at main pipe joining area with cross bracket is higher, the gap between the swing power unit and the cross bracket becomes very narrow restricting the articulation of the swing power unit.

Hence the objective of the present invention is to provide a frame structure for a scooter type motorcycle provided with a swing power unit capable of solving the above mentioned problems.

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 frame structure for a scooter is characterized by the fact that: the rear end of the aforementioned main pipe and bridge bracket consists of a C section formed by pressing a sheet metal with central opening to receive the main tube frame and the front ends of the pair of left and right rear frames are joined to the left and right ends of the aforementioned bridge bracket.

In another embodiment, the bridge bracket is joined with a flat plate that matches with the inner profile of the bridge bracket.

Further, the said bridge bracket is inverted and joined to main tube frame by welding and the flat plate is welded to its inner side before welding to main frame tube.

In another embodiment, the rear tubes and welded the bridge bracket at either ends and are rigidly connected by a plate welded to form engine link mounting.

An object of the present invention is to provide a frame structure for a scooter
type motorcycle which provides more stiffness to the frame.

Another object of the present invention is to provide ease of accessibility and
manufacturability.

Another object of the present invention to reduce the parts counts.

Yet another object of the present invention is to provide lateral stiffness in both
directions.

Brief description of the drawing:

These and other aspects of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a left side view of frame according to one of the embodiment of the present invention;

FIG. 2 is the top view of frame according to one of the embodiment of the present
invention;

FIG. 3 is the front view of frame according to one of the embodiment of the
present invention;

FIG. 4 is a rear view of frame according to one of the embodiment of the present
invention;

FIG. 5 is a rear perspective view showing a joint between main pipe and bridge
bracket.

FIG. 6 is a front perspective view showing the joint between main pipe and bridge
bracket.

Detailed description of the Invention:

In a scooter a front wheel and a rear wheel are supported by the frame assembly. A handle bar assembly is supported by the frame assembly in a position generally forwardly of an operator of the scooter. A seat assembly is supported generally rearwardly of the handlebar assembly and is configured to support an operator of the scooter in a straddle-type fashion. Preferably, a generally open area is defined between the handle bar assembly and the seat assembly to permit ease of mounting of the scooter by an operator.
The frame assembly also includes a head pipe which is connected to forward ends of the left and right frame rails. The head pipe supports a front fork assembly for a rotation about a steering axis. The front wheel is supported at a lower end of the fork for rotation about an axle. The rear wheel of the scooter is supported on a rearward end of a swing arm, a forward end of which is connected to the frame assembly by a pivot. Thus, the swing arm is pivotal relative to the frame assembly.

In the illustrated embodiment, the pivot is supported by a pair of brackets connected to a lower, rearward end of each of the horizontal portions of the frame rails.

According to the present invention and referring to the figure 1 a frame structure for a scooter, equipped with one main pipe (101) 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 (102), and a pair of left and right rear frames (201) (shown in figure 2) 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 (101), allowing the seat to be supported on these rear frames; wherein said frame structure for a scooter is characterized by the fact that: the rear end of the aforementioned main pipe and a bridge bracket (301) ( shown in figure 3) consists of a C section (701) (shown in figure 7) formed by pressing a sheet metal with central opening (601, shown in figure 6) to receive the main pipe (101) frame and the front ends of the pair of left and right rear frames are joined to the left and right ends of the aforementioned bridge bracket.

In another embodiment, the bridge bracket is joined with a flat plate (702) that matches with the inner profile of the bridge bracket (301).

Further, the said bridge bracket (301) is inverted and joined to main pipe (101) frame by welding and the flat plate (702) is welded to its inner side before welding to main frame tube.

In another embodiment, the rear tubes (201) are welded to the bridge bracket (301) at either ends and are rigidly connected by a plate (703) welded to form engine link mounting.

Two stiffeners (602) are welded at top and bottom side of the joint area of main pipe (101) and bridge bracket (301) at joint area to strengthen the joint.
Various modifications and adaptations may occur to those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.

We Claim

1. A frame structure for a scooter type motorcycle comprises:
a main pipe extending obliquely downward from head pipe;
a bridge bracket with central opening to receive the main pipe;
at least one stiffener covering the joint area of the bridge bracket and main
pipe; and
at least two rear frames extending obliquely rearwardly backwards from
the ends of the said bridge bracket.

2. The frame structure for a scooter type motorcycle as claimed in claim 1, wherein the said bridge bracket is preferably of C section formed by pressing a sheet metal.

3. The frame structure for a scooter type motorcycle as claimed in claim 2, wherein the said bridge bracket C section is joined with a flat plate which matches the inner profile of the bridge bracket.

4. The frame structure for a scooter type motorcycle as claimed in claim 1, wherein the said stiffener is preferably two in number, which are welded at top and bottom side of the joint area of main pipe and bridge bracket.

5. The frame structure for a scooter type motorcycle as claimed in claim 1, wherein the said main pipe is welded to the central opening in the bridge bracket.