JPH0764299B2 - Frame for motorcycle - Google Patents

Description

TECHNICAL FIELD The present invention relates to a frame of a motorcycle.

[Prior Art] Conventionally, in motorcycles, especially road sports vehicles, the engine mount part is interrupted at the down tube and the center part of the frame, and the engine is mounted on this part to make the crank case part of the frame. Some use a diamond frame that does. Also, a so-called wide frame is proposed in which the main frame is extended from the steering head pipe to the left and right of the vehicle body to increase the left and right width, thereby improving rigidity, improving the mountability of the engine and the appearance of the vehicle body, and improving rigidity. A number of innovations have been made in order to improve things. And, in the wide frame, since the left and right width is large, the fuel tank cannot be arranged in a state of enclosing the main frame,
The fuel tank was to be arranged above the main frame and the seat rail supporting the seat.

[Problems to be Solved by the Invention] By the way, in the structure of the above frame, the fuel tank is located at a high position in the vehicle body so that it can be pushed up by both the main frame and the seat rail, so that the center of gravity of the vehicle body becomes higher. Come on.

In solving this, the main frame cannot be changed from the relationship with the steering head pipe,
It is possible to make the seat rail as low as possible.
However, if this is carried out, there is a problem in that the force applied to the main frame is increased. Therefore, the main frame has strength sufficient to withstand the force applied to the main frame, and the production is facilitated without increasing the cost. Aim to get the frame.

[Means for Solving the Problems] The present invention has been made in consideration of the above-mentioned problems of the related art. The present invention extends laterally from the steering head pipe to the left and right sides, bends along the side edges of the tank, and then lowers rearward. A pair of right and left square pipes extending in the main frame, and a pair of left and right square pipes that support the seat and extend straight upward from the upper surface of each main frame toward the rear, and A front end is connected to each of the main frames, and a rear end is fixed to an intermediate portion of a seat rail below the seat to support a seat rail. It consists of a bracket that hangs from the rear part and pivotally supports a swing arm that supports the rear wheel. A motorcycle frame in which a fuel tank is placed on the main frame and the seat rail so that the rear portion of the fuel tank is located near the fixing of the seat rail and the seat pillar, and is fixed to the main frame. The front end of the seat rail is brought closer to the rear end of the main frame so that the entire seat rail is located below, the front end of the seat pillar is fixed to the upper surface of the rear end of the main frame, and the upper edge of the bracket is
The bracket is formed so that it extends linearly from the rear end of the main frame near the front end of the seat rail substantially along the axis of the main frame and is fixed to the main frame, and the front edge of the bracket is concave toward the rear. The present invention provides a motorcycle frame characterized in that the conventional drawbacks are eliminated.

[Operation] In the present invention, the fuel tank is mounted on the main frame and the seat rail so that the rear portion of the fuel tank is located near the fixing portion between the seat rail and the seat pillar, and the front end of the seat rail fixed to the main frame. Is brought close to the rear end of the main frame and the entire seat rail is lowered downward, so that the fuel tank mounted above the seat rail is lowered downward.

As shown in FIG. 3, the weight of the rider and the weight of the fuel tank are added to the seat rail A, and this load W is a force directed vertically downward at the intersection C between the seat rail A and the seat pillar B. work. Even if the seat rail A is lowered downward, the position at which the seat pillar B supports the seat rail A does not change, so that the angle D '(D>D') between the seat rail A and the seat pillar B becomes small. Therefore, a downward component force F ′ of the force acting on the intersection point C on the axis of the seat pillar.
Is the rearward component force E '(E <E') on the seat rail axis
It increases under the influence of (F <F '). The downward component force F'on the axis of the seat pillar acts to push the main frame downward. Although the force acting from the seat pillar to the main frame increases in this way, the upper edge of the bracket is extended linearly from the rear end of the main frame to near the front end of the seat rail almost along the axis of the main frame. Since the main frame is fixed to the frame, the main frame is reinforced by the bracket, and the range of the reinforcement extends to the vicinity of the front end of the seat rail, so that the strength of the main frame increases.

[Embodiment] Next, the present invention will be described in detail based on an embodiment shown in FIG. 1 and FIG.

In the figure, 1 is a frame of a motorcycle, and the frame 1 is a pair of main frames 3 and 3 made of square pipes that are divided into left and right along the side edge of the tank a from the upper end of the steering head pipe 2 and extend rearward and downward. A down tube 4 connected to the lower end of the steering head pipe 2 to support the front part of the engine c via a stay b, and a pair of left and right seat rails 5 and 5 connected to each of the main frames to support the seat b. And a pair of left and right seat pillars
6, 6 and a steel plate bracket 7 that is connected to each of the main frames and supports the rear part of the engine c. The down tube 4 supports the front part of the engine c and the steel plate bracket 7 supports the rear part of the engine c. However, the frame 1 is configured as a diamond frame having an extremely good engine mountability.

The seat rail 5 is formed of a square pipe, and is fixed by welding to the upper surface of the main frame 3 at a position where the front end is close to the rear end side of the main frame 3 as shown in the figure, and extends inward from the front end. It bends backward and extends straight toward the rear.

A front end of a seat pillar 6 made of a square pipe is welded and fixed to each upper surface of a rear end 30 of the main frame 3 which is located rearward from a connecting portion between the main frame 3 and the seat rail 5. The seat pillar 6 is bent inwardly, then extends toward the seat rail 5 side, and is connected to the seat rail 5 at the rear half straight portion 60, and supports the seat rail 5 to which the seat d is attached. .

The steel plate bracket 7 is welded and fixed to a portion of the main frame 3 excluding the upper surface of the rear end 30, and swingably supports a swing arm e. In the steel plate bracket 7, the upper edge 70 is linearly extended from the rear end 30 of the main frame 3 to the vicinity of the front end of the seat rail 5 along the axis of the main frame 3 as shown in FIG. It is fixed to the main frame 3. Further, the front edge 71 of the steel plate bracket 7 is formed so as to be concave toward the rear, so that the bearing does not come during the mounting work of the engine.

Thus, the seat rail 5 and the seat pillar 6 are
Are directly connected to the main frame 3 without being connected to the steel plate bracket 7, and the respective connecting work to the main frame 3, that is, the welding work becomes easy,
Manufacturing cost can be reduced.

The main frames 3 and 3 and the seat rails 5 and 5 are linear as seen in side view as shown in FIG. 1, and the shape before connection (welding) is bent in a plane perpendicular to the side surface of the square pipe. .
Therefore, the bending processes of the main frames 3 and 3 and the seat rails 5 and 5 are common to the left and right, and the manufacturing cost can be reduced also in this respect.

[Effects of the Invention] As described above, according to the motorcycle frame of the present invention, the pair of left and right corners that extend laterally from the steering head pipe and curve along the side edges of the tank and then extend rearward and downward. A main frame made of a pipe, a seat rail made of a pair of right and left square pipes extending in a straight line upward from the upper surface of each main frame and supporting a seat, and a front end of each main frame. A seat pillar composed of a pair of right and left square pipes connected to each other and having a rear end fixed to an intermediate portion of the seat rail below the seat, and fixed to the rear portion of each of the main frames and hanging from the rear portion, It also consists of a bracket that pivotally supports a swing arm that supports the rear wheels, and the engine is placed below the main frame. In the motorcycle frame, the fuel tank is placed on the main frame and the seat rail so that the rear portion of the fuel tank is located near the fixing of the seat rail and the seat pillar, and the seat rail fixed to the main frame is The front end is located close to the rear end of the main frame so that the entire seat rail is located below, and the front end of the seat pillar is fixed to the upper surface of the rear end of the main frame. It is characterized in that it is linearly extended near the front end of the rail along the axis of the main frame and fixed to the main frame, and that the front edge of the bracket is formed to be concave toward the rear. is there.

In this way, the fuel tank is placed on the main frame and the seat rail so that the rear portion of the fuel tank is located near the fixing portion between the seat rail and the seat pillar, and the front end of the seat rail fixed to the main frame is By lowering the seat rail as a whole by bringing it closer to the rear end of the main frame, the fuel tank placed above the seat rail is lowered downward, and thus the center of gravity of the vehicle body can be lowered and the seat height can be lowered. It is possible to obtain a vehicle that is easy to operate in combination with a low center of gravity because the rider's legability is improved by lowering the height.

Also, by lowering the seat rail as a whole, the force acting to push the main frame downward from the seat pillar in the axial direction of the seat pillar increases, but the upper edge of the bracket is moved from the rear end of the main frame to the front end of the seat rail. Since it was extended linearly along the axis of the main frame and fixed to the main frame in the vicinity, the main frame was reinforced with brackets, and the range of reinforcement was near the front end of the seat rail. Since the strength of will also increase, it will not be damaged. Further, the bracket does not require high precision such as one in which the shape is matched with the rear end of the main frame and fixed by butt welding, and the production is easy and the cost increase can be prevented. That is, even if the upper edge of the bracket extends to the vicinity of the front end of the seat rail, the front edge of the bracket is formed so as to be concave toward the rear, so that it is located below the main frame from the side. This has excellent practical effects, such as not hindering the work of mounting the engine.

[Brief description of drawings]

FIG. 1 is a side view of a vehicle incorporating an embodiment of a motorcycle frame according to the present invention, FIG. 2 is an explanatory view of the embodiment, and FIG. 3 is a seat rail lowered to act on a main frame. It is explanatory drawing which shows the state in which the component force to increase increases. 1 ... Frame, 3 ... Main frame 5 ... Seat rail, 6 ... Seat pillar 7 ... Steel plate bracket

Claims (1)

[Claims] 1. A main frame composed of a pair of left and right square pipes extending laterally from a steering head pipe along a side edge of a tank and then extending rearward and downward, and a main frame extending rearward from an upper surface of each main frame. Seat rails that extend slightly upward and are composed of a pair of right and left square pipes that support the seat, and the front ends are connected to the main frames, respectively, and the rear ends are fixed to the middle part of the seat rail below the seat. A seat pillar comprising a pair of right and left square pipes for supporting the seat rail, a bracket fixed to the rear portion of each of the main frames and hanging from the rear portion, and a bracket for pivotally supporting a swing arm for supporting the rear wheel, A motorcycle frame having an engine disposed below a main frame, wherein a rear portion of the fuel tank is a seat. Place the fuel tank on the main frame and seat rail so that it is located near the position where the trail and seat pillar are fixed, and bring the front end of the seat rail fixed to the main frame close to the rear end of the main frame so that the entire seat rail moves downward. The front end of the seat pillar is fixed to the upper surface of the rear end of the main frame, and the upper edge of the bracket is linearly extended from the rear end of the main frame to the vicinity of the front end of the seat rail substantially along the axis of the main frame. A motorcycle frame characterized in that it is extended and fixed to the main frame, and the front edge of the bracket is formed to be concave toward the rear.