JPH064430B2 - Frame structure of motorcycle - Google Patents

Description

The present invention relates to a frame structure of a motorcycle, and more particularly to a structure of a main frame portion extending from a steering head to a swing arm.

[Conventional technology]

In general, a motorcycle has a front fork for suspending front wheels steerably supported by a steering head provided at a front portion of a frame, and a rear axle is provided on a pivot shaft provided at a lower center portion (steering arm bracket) of the frame. While supporting a swing arm for suspension, a cushion unit for carrying a load is attached between the swing arm and the frame,
It is configured to drive the rear wheels with an engine mounted in the center of the frame, the driver straddles the seat mounted on the upper part of the vehicle body, grasps the handle attached to the front fork and attaches to the step mounted on both sides of the lower part of the frame. Maneuver with the posture of.

There are various forms of frames for motorcycles. First, they can be divided into a press frame made by press forming a steel plate and a pipe frame made by welding and assembling pipes.

The latter pipe frame can be divided into a diamond frame that uses the engine as a strength member and a cradle frame that makes the engine mounting part into a cradle.

In addition, the cradle frame is divided into a single cradle and a double cradle depending on whether the main frame portion from the steering head to the swing arm bracket is composed of one member along the center line or two members on the left and right. In addition, there are also semi-double cradles with these eclectic configurations.

By the way, as these frame structures, generally, a main frame portion forming a portion from the steering head to the swing arm bracket, left and right seat rail members extending rearward from an upper rear portion of the main frame portion, and the main frame portion. It is widely practiced to provide a rear lower part and left and right rear lower members that connect midway of the seat rail member.

The main frame portion is a portion where an engine is mounted inside or on a lower side, and a fuel tank, a seat front portion, and the like are attached to an upper portion thereof.

[Problems to be Solved by the Invention]

By the way, in the pipe frame of the conventional motorcycle, generally, the tips of the left and right main upper members and the left and right main lower members are coupled to the steering head, and the rear portions of the members are connected to each other to form a cradle-shaped main frame portion. Was formed, and the engine and various parts were installed inside it.

Documents disclosing such a frame structure include, for example, JP-A-59-156878 and JP-A-61-3607.
2 can be presented.

However, in such a conventional frame structure, since the main frame part is composed of upper and lower members, there are great restrictions on the mounting position of the engine, and further, the mounting position of in-vehicle parts such as an air cleaner and a battery is also large. There were restrictions.

In addition, if the main frame part from the steering head to the swing arm bracket is made of pipe material with a uniform cross section, the number of welding steps is large, and even if it is for mounting parts or preventing interference with other parts, it is too sharp. Since it is difficult to make such changes in cross section, it has not been possible to sufficiently improve space efficiency.

[Means for solving problems]

The present invention has been made in view of the above-mentioned prior art, and has a simple structure, can reduce the number of parts, can freely select the shape of the main frame portion, and can improve space efficiency. An object is to provide a frame structure for a motorcycle.

The present invention relates to a frame structure of a motorcycle having a main frame part made of a hollow welded structure extending from a steering head to left and right swing arm brackets, wherein the main frame part is from the steering head to the left and right swing arm brackets. Each of the left and right frame members is a curved member that projects laterally outward of the inner open box cross section, and the front part is curved to the vicinity of the center line of the vehicle body while keeping the inner open box cross section, and the rear part. In the rear end face open state, the upper and lower sides project inward to the vicinity of the center line of the vehicle body, and are formed by curved members formed so as to project laterally outward between these front and rear parts. The front portion of the member is welded to each other in the vicinity of the center line of the vehicle body while surrounding the entire circumference of the steering head, and Welding to the tearing head, the rear parts of the left and right frame members are welded to each other near the center line of the vehicle body, and are welded to the upper ends of the left and right swing arm brackets. By welding the left and right frame members into a hollow closed cross section, and by welding a lid member to the rear end open portions of the rear portions of the left and right frame members, a loop-like shape having a space where the upper end portion of the engine can be located is formed. The above object is achieved by a frame structure of a motorcycle, which is characterized by being constituted by a closed hollow structure.

〔Example〕

 The present invention will be specifically described below with reference to the drawings.

FIG. 10 is a schematic left side view of a motorcycle having a frame structure according to the present invention.

In FIG. 10, the frame is the steering head 11
From the swing arm bracket 12 to the swing arm bracket 12, the left and right rear lower members 14 and 14 and the left and right seat rail members 15 and 15 coupled to the rear side of the main frame portion 13, respectively. A front fork 17 for suspending a front wheel 16 is rotatably supported by the head 11, and a swing arm 19 for suspending a rear wheel 18 is swingably supported by the swing arm bracket 12 so that the swing arm 19 is swingable. And frame (swing arm bracket 12 in the example shown)
A cushion unit 20 for carrying a load on the rear wheel is attached between and.

An engine 21 for driving the rear wheels 18 is attached to the lower side of the main frame portion 13, and a fuel tank 22 is attached to the upper side of the main frame portion 13. As will be described later, the main frame portion 13 is divided into two left and right portions above the engine 21, and the upper end portion of the engine 21 is located in the space between them.

A seat 23 is attached to the rear side of the fuel tank 22 using the left and right seat rail members 15, 15 and the like.
The driver straddles the seat 23, and the front fork 1
The driver operates while holding the handle 24 attached to the vehicle 7 and placing his / her foot on the step 25 attached to the lower portion of the frame.

1 is a perspective view of the frame of the motorcycle shown in FIG. 10, that is, a frame according to an embodiment of the present invention, FIG. 2 is a left side view of FIG. 1, and FIG. FIG. 4 is a plan view of the drawing, and FIG. 4 is a cross-sectional view of the main frame portion taken along line IV-IV in FIG. 2.

1 to 4, the main frame portion 13 extending from the steering head 11 to the swing arm bracket 12 is a frame member 3 having left and right inner open box-shaped cross sections.
1A and 31B are joined at their front portions 32A and 32B and rear portions 33A and 33B, and lid members (usually plate members) 34A and 34B are fixed (welded) to the inner open portion of each frame member 31A and 31B. Has become.

Each of the frame members 31A and 31B is a curved member protruding outward in the middle part, and the front part 32 thereof is provided.
By welding the A, 32B and the rear portions 33A, 33B, the loop-shaped main frame portion 13 having a predetermined width is formed, and then the plate-shaped lid members 34A, 34B are welded to the open surfaces of the respective frame members 31A, 31B. Then, each frame member 31A, 31B is formed as a member having a closed cross section as a whole.

In the illustrated example, the lid member 35 is also fixed to the rear open surfaces of the rear welded portions 33A and 33B of the frame members 31A and 31B.

In the illustrated example, the left and right frame members 31A, 31B
Are welded along the vehicle body center line CL.

FIG. 5 is a rear view of the main frame portion as seen from the line VV in FIG.

In FIG. 5, the swing arm bracket 12
Is composed of left and right bracket members 12A, 12B extending downward from the rear end portions of the left and right frame members 31A, 31B and a cross member 36 connecting these bracket members 12A, 12B.
B is provided with concentric swing arms 19 (FIG. 10) pivoting pivots 37, 37.

FIG. 6 is a partial sectional view taken along line VI-VI in FIG.

As shown in FIGS. 1 to 3 and 6, the front portions of the left and right frame members 31A and 31B have a shape surrounding the steering head 11, and are welded to each other along the vehicle body center line CL. Is the steering head 11
Is welded to the peripheral surface.

FIG. 7 is a partial cross-sectional view of the connecting portion of the rear portions 33A, 33B of the left and right frame members 31A, 31B along the line VII-VII in FIG.

In FIG. 7, each frame member 31A (3rd frame
(Figs.) And 31B are formed into an inner open box-shaped cross section, and at this time, the vehicle body center CL is formed at the same time as the front parts (inner open) 32A and 32B protruding so as to surround the steering head 11 (Fig. 3). Rear part (open inside) Front part 3
3A and 33B are formed, and the joint end surfaces of the rear portions 33A and 33B are welded to each other, and the plate-shaped lid members 34A, 34B, and 35 are welded to the front and rear open surfaces to form a closed box-shaped cross section.

8 and 9 are lines VIII-VIII in FIG. 3, respectively.
9 is a partial cross-sectional view taken along line IX-IX.

The left and right frame members 31A and 31B (Fig. 3) are curved members each having an open inner box shape, and are usually made by a steel plate press forming method. Therefore, the outer surface shapes of the left and right frame members 31A and 31B (Fig. 3) can be freely formed into arbitrary shapes. Therefore,
As shown in FIGS. 1 to 3 and FIGS. 8 and 9, the handle escape portion 38 for preventing interference when the handle 24 (FIG. 10) is steered to the maximum left or right,
38, moreover, the knee relief portions 39, 39, etc. for preventing the driver's knee from colliding and realizing a good knee grip when driving over the seat 23 (FIG. 10) are facilitated. Can be formed.

In addition, a mounting seat 40 for mounting a desired number of transmission components and the like is provided at an appropriate position of the main frame portion 13 (inner surface of the front portion in the illustrated example), and the steering head 11 of the main frame portion 13 is further provided. A guide passage 41 for a cable, a harness or the like, which is formed of a pipe fixed to penetrate from the inside to the outside, is formed at positions near both sides of the.

Desired position of each frame member 31A, 31B (front portions 32A, 32B and rear portions 33A, 33B in the illustrated example)
Partition plates 42, 42, 43, 43 for reinforcement are welded to the inside of the.

Further, a cushion support fitting 44 for connecting the rear cushion 20 (FIG. 10) is welded to the center of the rear portion of the main frame portion 13.

According to the structure of the embodiment described above, the left and right frame members 31A and 31B are formed by the curved member having the inner open box-shaped cross section, and the front portions 32A and 32B and the rear portions 33A and 33B of these frame members 31A and 31B are welded. A plate-like lid member 34 is formed along the inner opening portion while being combined
Since A and 34B are welded to form the main frame portion 13, the shape structure of the main frame portion can be freely selected, and a more rational frame design is possible.

As an example, the front end of the main frame portion 13 can surround the steering head 11 and be welded together,
The welding line was lengthened and it was easy to disperse over a wide range, and workability could be improved.

Further, since the front and rear portions of the left and right frame members 31A and 31B are projected to near the center line of the vehicle body and welded to each other, the main frame portion 13 has a loop shape with a predetermined width. Since it is possible to omit the reinforcing members such as members, the frame structure can be simplified and the appearance of the frame structure can be improved.

Further, the outer surfaces of the left and right frame members 31A and 31B can be freely selected in shape in consideration of interference with other components and landing positions, and the space efficiency of the vehicle body can be further improved.

Furthermore, it became easy to form a metal fitting and a mounting seat for mounting small accessories such as electrical equipment.

In the illustrated embodiment, the main frame portion 13 is formed only by the left and right upper members forming the backbone. However, this is a grade type by adding a main lower member (or down tube) to the illustrated main frame portion 13. It is also possible to configure the main frame portion.

〔The invention's effect〕

As is apparent from the above description, according to the present invention, in the frame structure of the motorcycle having the main frame part formed of the hollow welded structure extending from the steering head to the left and right swing arm brackets, the main frame part is , The left and right frame members from the steering head to the left and right swing arm brackets are curved members that extend laterally outward of the inner open box cross section, and the front open part remains the open box cross section. Curved to the vicinity of the center line of the vehicle body, and at the rear part, with the rear end face open, the upper side and the lower side project inward to the vicinity of the center line of the vehicle body, and are formed so as to project laterally outward between these front and rear parts. It is formed of a curved member, and the front portion of the left and right frame members surrounds the entire circumference of the steering head. The left and right frame members are welded to each other in the vicinity of the center line and to the steering head, and the rear portions of the left and right frame members are welded to each other in the vicinity of the center line of the vehicle body and to the upper ends of the left and right swing arm brackets. By welding a lid member to the inner open portion of the member to make the left and right frame members have a hollow closed cross section, and welding the lid member to the rear end open portions of the rear portions of the left and right frame members, the upper end portion of the engine is Since it is configured with a loop-shaped closed hollow structure having a space where it can be located, it is possible to improve the degree of freedom in the shape and structure of the main frame part, and also to improve the degree of freedom in the layout of each part of the vehicle body. Can be simple structure, space efficient,
Provided is a motorcycle frame structure having an excellent appearance.

[Brief description of drawings]

1 is a perspective view of an embodiment of a frame structure for a motorcycle according to the present invention, FIG. 2 is a left side view of the frame structure of FIG. 1, and FIG. 3 is a plan view of the frame structure of FIG. 4, FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2, FIG. 5 is a partial arrow view seen from line VV in FIG. 2, and FIG. 6 is in FIG. FIG. 7 is a sectional view taken along line VI-VI of FIG. 7, and FIG. 7 is a line VII-V in FIG.
A cross-sectional view along line II, FIG. 8 and FIG.
Sectional views taken along lines VIII-VIII and IX-IX in the figure, and FIG. 10 is a left side view of a motorcycle having the frame structure of FIG. 11 ... Steering head, 12 ... Swing arm bracket, 13 ... Main frame part, 31A, 31
B ... Frame member, 32A, 32B ... Front part (frame member), 33A, 33B ... Rear part (frame member), 34A, 34B ... Lid member.

Claims (1)

[Claims] 1. A frame structure of a motorcycle having a main frame part made of a hollow welded structure extending from a steering head to left and right swing arm brackets, wherein the main frame part is from the steering head to the left and right swing arm brackets. Each of the left and right frame members is a curved member that projects laterally outward of the inner open box-shaped cross section, and is curved to the vicinity of the center line of the vehicle body while keeping the inner open box-shaped cross section in the front part, and In the rear part, with the rear end face open, the upper side and the lower side project inward to the vicinity of the center line of the vehicle body, and are formed by curved members formed so as to project laterally outward between the front part and the rear part. The front portion of the frame member is welded to each other in the vicinity of the center line of the vehicle body while surrounding the entire circumference of the steering head, and Welding to the tearing head, the rear parts of the left and right frame members are welded to each other near the center line of the vehicle body, and are welded to the upper ends of the left and right swing arm brackets. By welding the left and right frame members into a hollow closed cross section, and by welding a lid member to the rear end open portions of the rear portions of the left and right frame members, a loop shape having a space where the upper end of the engine can be located A frame structure for a motorcycle, comprising a closed hollow structure.