JPH06171570A - Frame structure of motorcycle - Google Patents

Abstract

PURPOSE:To provide the frame structure of a motorcycle to reduce the cost and ensure a necessary sufficient strength and rigidity. CONSTITUTION:A rear arm bracket 12 to rotatably support a rear arm is formed of a channel member in a U-shape in cross section provided by press- molding a plate. The peripheral edge of the opening thereof is welded to a corner part between a tank rail 5 and a down tube 6. Since a channel member of which the rear arm bracket 12 is formed is easily produced by press-molding, for example, a low-cost steel plate, the material cost and manufacturing cost are reduced. Further, since the channel member is formed in a U-shape in cross section, a necessary sufficient strength and rigidity are ensured from a geometric shape and weight is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frame structure for a motorcycle.

[0002]

2. Description of the Related Art A rear wheel of a motorcycle is rotatably supported by a rear end portion of a rear arm, and a front end portion of the rear arm is rotatably supported by a rear arm bracket forming a part of a vehicle body frame.

By the way, since the above-mentioned rear arm bracket has conventionally been a cast product of, for example, an aluminum alloy,
The material and the manufacturing cost are high, which has been a factor of increasing the cost of the entire body frame.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a frame structure for a motorcycle which is inexpensive and can secure necessary and sufficient strength and rigidity.

[0005]

In order to achieve the above object, the present invention comprises a rear arm bracket for rotatably supporting a rear arm, which comprises a channel member having a U-shaped cross section obtained by press-molding a plate material, The feature is that the periphery of the opening end is welded to the corner of the pipe frame.

[0006]

According to the present invention, the channel member constituting the rear arm bracket can be easily obtained by press-molding an inexpensive steel plate, for example, so that the material and manufacturing cost thereof are reduced as compared with the conventional one.

Further, since the channel member is formed in a U-shaped cross section, its geometrical shape ensures necessary and sufficient strength and rigidity, and is lightweight.
The peripheral edge of the open end of the channel member is adhered to and welded to the pipe frame along the outer periphery of the pipe frame, so that the rear arm bracket has a necessary and sufficient attachment strength.

[0008]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

First, the schematic construction of the motorcycle will be described with reference to FIG.

FIG. 13 is a side view of the motorcycle. In FIG. 13, reference numeral 1 denotes a head pipe which constitutes a part of a vehicle body frame. A steering shaft (not shown) is rotatably inserted into the head pipe 1. The handle 2 is attached to the upper end of the handle 2. An upper end of a front fork 3 is attached to the steering shaft, and a front wheel 4 is rotatably supported on a lower end of the front fork 3.

On the other hand, from the head pipe 1, a pair of left and right tank rails 5 and a down tube 6 constituting a vehicle body frame extend rearwardly and vertically, and a space formed by both of them has 4 cycles 4 cycles. Cylinder engine 7
Is stored. A fuel tank 8 is arranged above the engine 7, and a tandem seat 9 is arranged behind the fuel tank 8. Note that four exhaust pipes 10 extend from the engine 7, and these exhaust pipes 10 are assembled and connected to one muffler 11 arranged on one side of the vehicle body.

A pair of left and right rear arm brackets 12 are attached to a corner portion where the tank rail 5 and the down tube 6 are connected, and the rear arm bracket 12 has a front end of a rear arm 13 attached to the pivot shaft 1.
It is rotatably supported up and down at 4.

A rear wheel 15, which is a drive wheel, is rotatably supported by the rear end of the rear arm 13, and the rear arm 13 is suspended from the vehicle body frame via a pair of left and right rear cushions 16. .

Here, the detailed structure of the vehicle body frame is shown in FIG.
It will be described with reference to FIGS. 1 is a side view of the vehicle body frame, FIG. 2 is a plan view of the vehicle body frame, FIG. 3 is a partial front view of the vehicle body frame, FIG. 4 is an enlarged sectional view taken along line AA of FIG. 1, and FIG. 6 is an enlarged sectional view taken along line BB of FIG. 3, FIG. 6 is a side view of the rear arm bracket, FIG. 7 is a plan view of the rear arm bracket, FIG. 8 is a sectional view taken along line CC of FIG. 6, and FIG.
10 is a side view of the rear cushion bracket, FIG. 11 is a sectional view taken along the line EE of FIG. 10, and FIG. 12 is a sectional view taken along the line FF of FIG.

As shown in FIGS. 1 and 2, the pair of left and right down tubes 6 is formed by three-dimensionally bending one round pipe made of steel, which is rearward from the lower portion of the head pipe 1. After extending obliquely downward while expanding toward, it is bent and extends backward and parallel and horizontally, and is bent again and rises obliquely upward and backward, and its end is also a round pipe. It is bound to the horizontal middle portion of the seat rail 17 that is formed. As shown in FIG. 3, a portion of the down tube 6 near the head pipe 1 is reinforced by a flat plate-shaped gusset 18, and a lower portion 6a thereof is flattened to avoid interference with the exhaust pipe 10. It is formed into an oval cross section (see FIG. 5). In addition, at a portion below the flat portion 6a of the down tube 6, two engine mount bosses 1 are provided on the upper and lower sides.
9 is inserted and bound.

On the other hand, the pair of left and right tank rails 5 are also made of steel round pipes, which branch off from the upper part of the head pipe 1 in a bifurcated manner and gradually extend rearward and obliquely downward. While being bent and gradually expanding its width, it extends rearward and obliquely downward, and its end is connected to an intermediate position of the rising portion of the down tube 6. Since the tank rail 5 has a larger diameter than the down tube 6, the portion 5a of the tank rail 5 near the joint with the down tube 6 is flattened according to the diameter of the down tube 6 as shown in FIG. It has been devised that the large-diameter tank rail 5 is rationally attached to the small-diameter down tube 6 by being crushed into a rectangular shape.

By the way, a portion of the tank rail 5 near the head pipe 1 is reinforced by a gusset 20, and a cross pipe 21 is laterally bridged behind the gusset 20.
An air cleaner bracket 22 is attached to the. Further, a pair of left and right engine mount brackets 24 are attached to a cross pipe 23 which is laterally bridged in the portion of the tank rail 5 near the joint with the down tube 6.

A pair of left and right tension pipes 25 are installed between the tank rail 5 and the down tube 6, and the tank rail 5 and the down tube 6 and the down tube 6 and the tension pipe 25 form a left and right pair. Are reinforced by gussets 26 and 27, respectively. still,
A tank bracket 28 is attached to an intermediate position of each tension pipe 25.

On the other hand, the seat rail 17 is formed in a U-shape in plan view as shown in FIG. 2, and its front end is connected to the tank rail 5. And the seat rail 1
7 is reinforced by a cross pipe 29, to which a tank bracket 30, seat brackets 32 and 33, a rear fender bracket 34, etc. are attached.

By the way, the pair of left and right rear arm brackets 12 are provided at the corners of the joint between the tank rail 5 and the down tube 6 as shown in the figure.
Are connected along the down tube 6 and the details of the construction and attachment of the rear arm bracket 12 will be described with reference to FIGS. 6 to 9.

Each rear arm bracket 12 is composed of a channel member having a U-shaped cross section obtained by press-molding a steel plate. The peripheral edge of the opening of the rear arm bracket 12 is welded to the tank rail 5 and the down tube 6 so that it is attached to the vehicle body frame. It is installed.

That is, as shown in FIG. 8, the short side opening edge 12a of the rear arm bracket 12 is bent outward along the outer periphery of the tank rail 5 having an oval cross section, and the bent portion 12a of the tank rail 5 is bent. It is adhered and welded to the outer periphery. Further, as shown in FIG. 9, the long side opening peripheral edge 12b of the rear arm bracket 12 is bent outward along the outer periphery of the down tube 6, and the bent portion 12b is adhered and welded to the outer periphery of the down tube 6. ing. In the rear arm bracket 12, the bent portions 12a and 12b are the rear arm bracket 1
It may be formed at the same time as 2 is press-molded into a U-shaped cross section, or may be formed after U-shaped press molding.

Then, each rear arm bracket 12 is
A part thereof is cut out in a notched circle shape, and the rear arm mounting boss 35 and the engine mount boss 3 are provided in the notched portion.
6 is fitted and welded. The rear arm 13 (see FIG. 13) has the pivot shaft 14 supported by the pair of left and right rear arm bosses 35.
(See FIG. 13), it is rotatably supported up and down.

On the other hand, as shown in FIG. 1, a pair of left and right reaction brackets 3 each having a triangular shape in a side view are provided at the corners of the connecting portion between the down tube 6 and the seat rail 17.
7, the details of the construction and attachment of the reaction bracket 37 will be described with reference to FIGS. 10 to 12.

Each rear bracket 37 supports the upper end of the rear 16 (see FIG. 13), and is constructed and mounted in the same manner as the rear arm bracket 12.

That is, each of the reaction brackets 37 is composed of a channel member having a U-shaped cross section obtained by press-molding a steel plate, which has an opening peripheral edge 37a on the short side as shown in FIG. The outer peripheral edge 37b of the long side is bent outwardly along the outer periphery of the outer peripheral portion 6 of FIG.
As shown in FIG. 3, the seat rail 17 is bent outward along the outer periphery thereof, and the bent portions 37a and 37b are adhered and welded to the down tube 6 and the seat rail 17, respectively.

As described above, in this embodiment, since the channel member forming the rear arm bracket 12 is obtained by press-molding an inexpensive steel plate, there is an advantage that the material and the manufacturing cost thereof are reduced as compared with the conventional one. To be

Further, since the channel member constituting the rear arm bracket 12 is formed in a U-shaped cross section, its geometrical shape ensures necessary and sufficient strength and rigidity, and is lightweight. In the rear arm bracket 12 formed of this channel member, the opening peripheral edges 12a and 12b are closely adhered and welded to the outer circumferences of the tank rail 6 and the down tube 5, respectively.
The rear arm bracket 12 has a necessary and sufficient mounting strength.

[0029]

As is apparent from the above description, according to the present invention, the rear arm bracket for rotatably supporting the rear arm is constituted by the channel member having a U-shaped cross section obtained by press-molding a plate material, Since the peripheral edge of the opening end is welded to the corner of the pipe frame, it is possible to obtain a frame structure for a motorcycle that is inexpensive and can secure necessary and sufficient strength and rigidity.

[Brief description of drawings]

FIG. 1 is a side view of a body frame of a motorcycle.

FIG. 2 is a plan view of the body frame of the motorcycle.

FIG. 3 is a partial front view of the body frame of the motorcycle.

FIG. 4 is an enlarged cross-sectional view taken along the line AA of FIG.

5 is an enlarged sectional view taken along line BB of FIG.

FIG. 6 is a side view of a rear arm bracket.

FIG. 7 is a plan view of a rear arm bracket.

8 is a cross-sectional view taken along line CC of FIG.

9 is a cross-sectional view taken along line DD of FIG.

FIG. 10 is a side view of a rear cushion bracket.

11 is a cross-sectional view taken along the line EE of FIG.

12 is a sectional view taken along line FF of FIG.

FIG. 13 is a side view of the motorcycle.

[Explanation of symbols]

 5 Tank rail (pipe frame) 6 Down tube (pipe frame) 12 Rear arm brackets 12a, 12b Edge of rear arm bracket opening 17 Seat rail

Claims (1)

[Claims] 1. A rear arm bracket for rotatably supporting a rear arm is constituted by a channel member having a U-shaped cross section obtained by press-molding a plate material, and an opening end peripheral edge thereof is welded to a corner portion of a pipe frame. The frame structure of the motorcycle, which is characterized by that.