JPH0366191B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a frame structure of a motorcycle (including saddle riding type three-wheeled and four-wheeled vehicles), particularly the structure of a portion related to intake system members.

(Prior Art) In general, the frame structure of a motorcycle is such that one main tube 101 and one down tube 102 are formed diagonally downward from a head pipe 100, as shown in FIGS. 6A and B and FIGS. 7A and B. A rear frame 103 consisting of left and right members 103a, 103a extends rearward from the rear end (lower end) of the main tube 101, and also consists of left and right members 104a, 104a downward from the rear end (lower end) of the main tube 101. The center tube 104 is extended, and an engine 105 is mounted in the space formed by the main tube 101, the down tube 102, and the center tube 104, and an air cleaner case 106 is supported on the lower surface of the rear frame 103.
6 and a carburetor 107 provided on the upper rear side of the engine 105 through a connecting tube 108.
It is connected at.

(Problems to be Solved by the Invention) The conventional frame structure described above causes the following problems.

First, in order to prevent interference between the carburetor 107, the connecting tube 108, and the main tube 101, the engine 105 and the main tube 10 are connected as shown in FIGS. 6A and 7A.
1, and in some cases, the connecting tube 108 must be connected to the carburetor 107 by turning it around the side of the vehicle body as shown in FIG.

As the height of the main tube 101 increases in this way, the positions of the fuel tank and seat also inevitably become higher, making it difficult to keep the center of gravity of the vehicle low.Furthermore, as the connecting tube 108 protrudes laterally, the width of the vehicle body increases. becomes large.

Furthermore, if the frame structure is as described above, the connecting tube 108 can be connected to the side surface of the air cleaner case 106 (FIG. 6), or the connecting tube 108 can be connected to the front surface of the air cleaner case 106 (FIG. 7). Therefore, the water that entered the air cleaner case 106 is
In order to avoid affecting the carburetor 107, a special water draining device will be provided.

(Means for Solving the Problems) In order to solve the above problems, the present invention consists of a main tube made up of a pair of left and right members, and the front ends of the left and right members constituting the rear frame are connected to these members. The main tube and rear frame formed a V-shaped side surface, and an air cleaner case whose upper surface sloped forward and downward was attached to the lower surface of the rear frame, and the air cleaner case was led out from the front upper surface of the air cleaner case. The connecting tube is connected to a carburetor disposed between the pair of left and right members constituting the main tube, and the carburetor and the connecting tube are located above the joint between the main tube and the rear frame when viewed from the side. It was located at .

(Example) Examples of the present invention will be described below based on the accompanying drawings.

FIG. 1 is an overall side view of a motorcycle to which a frame structure according to the present invention is applied, FIG. 2 is a plan view of the same motorcycle, and FIG. 3 is a perspective view of the main parts of the frame as seen obliquely from the rear.

The frame 2 of the motorcycle 1 includes a head pipe 3
A main tube 4 extends diagonally rearward and downward from the upper end, and a down tube 5 extends obliquely rearward and downward from the lower end of the head pipe 3. The main tube 4 consists of a pair of left and right members 4a, 4a, each member 4a, 4a gathers at the head pipe 3, gradually expands downward, and has a lower end curved forward. . The down tube 5 also includes a pair of left and right members 5a, 5a, and these members 4a, 4a, 5a, 5a form a space in the form of a substantially quadrangular pyramid. An upper cross member 6a and a lower cross member 6b are installed between the members 4a, 4a forming the main tube 4.

Further, the rear frame 8 extends diagonally rearward and upward from the intermediate portion of the main tube 4, so that the main tube 4 and the rear frame 8 form a V-shape on the side. This rear frame 8 consists of a pair of left and right members 8a, 8a, and the front end of each member 8a, 8a is a member 4 forming the main tube 4.
a, 4a. The front portions of the members 8a, 8a constituting the rear frame 8, that is, the portions on which the occupant's knees come into contact when the occupant straddles the seat, are bent inward.

Further, a back pipe 9 is installed diagonally between the intermediate portion of the rear frame 8 and the main tube 4. This back pipe 9 also consists of a pair of left and right members 9a, 9a, as described above.

Here, each member constituting the main tube 4, down tube 5, rear frame 8, and back pipe 9 is an elliptical tube that is flattened in the horizontal direction, improving longitudinal rigidity and narrowing the overall width of the vehicle body. I'm trying to do what I can.

An upper bridge 10 and a lower bridge 11 to which the handle pipe 7 is fixed are attached to the upper and lower ends of the head pipe 3, and between these upper bridge 10 and lower bridge 11, the upper ends of left and right front fork members 12, 12 are supported. Front fork member 12,
A shaft 14 of a front wheel 13 is rotatably supported at the lower end of the wheel 12 .

In addition, main tube 4 and down tube 5
An engine 15 is disposed in the quadrangular pyramid-shaped space formed by the structure.The engine 15 is attached and supported by brackets provided on the main tube 4 and the down tube 5, and the upper end of the engine 15 is attached to the upper cross member. It is directly supported by 6a. The lower part of the engine 15 is covered with an aluminum alloy cover 16 attached between the lower ends of the main tube 4 and the down tube 5 to protect the engine 15 from bottoming out.

At the back of the upper part of the engine 15 is a carburetor 17.
The carburetor 17 projects rearward and upwardly from the main tube 4 when viewed from the side as shown in FIG. be done. Further, an exhaust pipe 18 is led out from the lower front surface of the engine 15, and this exhaust pipe 18 curves in front of the engine 15.
The muffler 19 extends rearward along the right side of the vehicle body.
connected to.

In addition, the members 4 who make up the main tube 4
A fuel tank 20 is installed over the tops of a and 4a,
An air cleaner case 21 is attached to the lower part of the members 8a, 8a constituting the rear frame 8, and a connecting tube 22 connected to the carburetor 17 projects from the front upper surface of the air cleaner case 21. As shown in FIGS. 4 and 5, this connecting tube 22 protrudes upward between the members 8a and 8a and further than the members 8a and 8a when viewed from the side.

A rear fender 24 that covers the upper part of the rear wheel 23 is fixed to the rear frame 8, and a cover 25 that covers the upper surface of the fuel tank 20, the upper surface of the air cleaner case 21, and the front surface of the rear fender 24 is attached. A seat portion for the occupant to sit on is attached to the upper surface of the cover 25, and the side surface is approximately V-shaped, with the valley portion being the portion that corresponds to the knee of the occupant, and the valley portion constitutes the rear frame 8 as described above. member 8a,
The shape is narrowed inward to accommodate the inwardly bent portion of 8a. In addition, by locating the protruding position of the connecting tube 22 at the rising part in front of the valley part of the cover 25, the seating position of the occupant can be lowered.

On the other hand, members 4 who make up the main tube 4
A pivot shaft 27 is inserted through the lower end portions of the rear fork 28 through the gusset plate 26, and the front end portion of the rear fork 28 is pivotally connected to the shaft 27 so as to be able to swing vertically.
The rear wheel 23 is rotatably supported at the rear end of the rear fork 28. Also, at the rear end of the rear fork 28 is a cam mechanism 29 for adjusting the tension of the drive chain.
has been established.

On the other hand, an upward protrusion 30 is provided at the front part of the rear fork 28, and the intermediate part of an arm 31 is pivotably supported by this protrusion 30, and one end of this arm 31 is provided on the frame side. It is pivotably supported on a bracket 32, and the rear end of a shock absorber 33 is pivotally connected to the other end of the arm 31. This buffer 3
3 has a horizontal arrangement extending in the longitudinal direction of the vehicle body,
Its front end portion is pivotally connected to a bracket 34 provided on the left member 4a of the left and right members 4a, 4a constituting the main tube 4. Thus, the shock absorber 33 is arranged offset to the left with respect to the vehicle body axis, and a space corresponding to that amount is formed on the right side of the shock absorber 33. Therefore, in the present embodiment, a part of the air cleaner case 21 is exposed to this space in order to make effective use of the space.

Incidentally, the angle between the line connecting both ends of the arm 31 and the center line of the rear fork 28 is set to 90° or less. Therefore, the rear wheel 2 hits the convex part of the road surface.
When the rear fork 28 swings counterclockwise in FIG. 1, the arm 31 also swings counterclockwise.
The amount of forward movement of the end to which the rear end of 3 is pivoted is small when the rear fork 28 starts to swing upward, and as the amount of swing increases, the amount of forward movement also increases. The absorption amount is increased in accordance with the impact energy applied to the rear wheel 23.

(Effects of the Invention) As explained above, according to the present invention, since the main tube can be lowered lower than before, the rear frame connected to the main tube can also be positioned lower, and the seat and air cleaner case can be lowered. It can be installed in a low position, allowing the center of gravity of the vehicle to be kept low while maintaining the minimum ground clearance. In addition, since the connecting tube is led out from the top surface of the air cleaner case, even if water should flow into the air cleaner case, it is possible to prevent the water from affecting the carburetor without adding a special water drainage device. The connecting tube is designed to protrude above the joint between the main tube and the rear fork, making it easy to maintain.Furthermore, the seat width can be made narrower, making it suitable for trial type motorcycles. It has many effects.

[Brief explanation of drawings]

FIG. 1 is an overall perspective view of a motorcycle to which the frame structure according to the present invention is applied, FIG. 2 is a plan view of the same motorcycle, FIG. The figure is a side view showing the positional relationship between the engine, auxiliary equipment, and the frame, Figure 5 is a plan view showing the same positional relationship, Figures 6A, B, and 7A,
B is a diagram showing the frame structure of a conventional motorcycle. In the drawings, 1 is a motorcycle, 2 is a frame, and 3 is a motorcycle.
1 is a head pipe, 4 is a main tube, 4a is a member constituting the main tube, 5 is a down tube, 8 is a rear frame, 8a is a member constituting the rear frame, 15 is an engine, 17 is a carburetor, 21 is an air cleaner case, 22 25 is a connecting tube, 25 is a cover, 28 is a rear fork, and 33 is a shock absorber.

Claims (1)

[Claims] 1. A main tube consisting of a pair of left and right members is extended obliquely backward and downward from the head pipe, and the front ends of the left and right members that constitute the rear frame that slopes forward and downward are connected to each member to form the main tube. and the rear frame to form a V-shape on the side, and an air cleaner case whose upper surface slopes forward and downward is attached to the lower surface of the rear frame, and a connecting tube is led out from the upper front surface of the air cleaner case. This connecting tube is connected to a carburetor located between the pair of left and right members constituting the main tube, and furthermore, the carburetor and the connecting tube are located above the joint between the main tube and the rear frame. A motorcycle frame structure characterized by: