JPH03114983A - Diamond type frame for motorbicycle - Google Patents

Abstract

PURPOSE:To ensure light weight and high rigidity, and improve a balance in strength by integrating a main pipe having a pair of seat rails connected to the rear part thereof with a seat pillar tube having a cross tube connected to the lower end thereof, and connecting a pair of back stays to both ends of the cross tube. CONSTITUTION:A main pipe 2 extended from a steering head pipe 1 is integrated with a seat pillar tube 5. As a result, a most optimum riding posture can be obtained and a frame can be made lightweight. In addition, the intermediate part of a cross tube 13 having the same axial length as the separation width of seat rails 6 is welded to the lower end of the tube 5, and back stays 14 are provided at both right and left ends of the tube 13, and the intermediate parts of the rails 6. The stays 14, therefore, are linearly extended via the outside of rear arm members 18, and the separation width of the stays 14 can be enlarged over the entire length thereof. Also, the lower ends of the stays 14 are connected to each other with a tube 13, thereby ensuring the required performance of a cross member. In addition, the torsional rigidity and lateral rigidity of the whole frame can be increased, and a frame superior in strength balance can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a diamond-shaped frame for a motorcycle.

[Prior Art] A diamond-shaped frame that uses the engine crankcase as part of the frame structure has the advantage of being lightweight and allows for a narrow frame configuration, and is particularly suitable for small and medium displacement vehicles. It is widely used in motorcycles.

By the way, in order to simplify the frame structure and reduce the weight of this type of frame, a frame with a main pipe that extends from the head vibrator to the rear through above the engine, and a seat pillar tube that is connected to this main pipe are used as a single frame. It has been known.

In this frame, a pair of left and right seat rails extending in the J direction are welded to the rear of the main pipe, and an engine bracket that supports the rear end of the engine C crankcase is welded to the lower end of the seat pillar tube. . A pair of left and right backstays (backstays) are welded to the left and right side surfaces of this engine bracket, which extend rearward and diagonally upward and are connected to the seat rail.

[Problems to be Solved by the Invention] However, in the conventional configuration in which the backstay is welded to the engine bracket, the separation width C of the seat rail is much wider than the left and right width of the engine bracket. The backstay must be bent towards the inside of the frame at 4.

As a result, the width of the gap on the lower side of the backstay becomes narrower, which reduces the lateral rigidity of the entire frame, and causes the load to concentrate on the engine bracket at the lower end of the seat pillar tube, resulting in a problem of poor frame strength balance. be.

The present invention was made based on the above circumstances, and an object of the present invention is to provide a diamond-shaped frame for a motorcycle that is lightweight, has sufficient rigidity, and has excellent strength balance.

Means for Solving Problem C] Therefore, in the present invention, a main pipe extending rearward and a down tube extending downward are connected to the head vibe, and the rear part of the main pipe is guided downward to form a seat pillar tube. The front and rear parts of the engine are connected between the lower end of the seat pillar tube and the lower end of the down tube, and the engine is used as part of the frame structure of a motorcycle. In the frame, the main pipe and the seat pillar tube connected thereto are one, and a pair of left and right seat rails extending rearward are connected to the rear part of the main pipe, and a lower end of the seat pillar tube is connected to the rear part of the main pipe. The cross tubes extending in the left and right direction are connected approximately in the middle, and are led out rearward and diagonally upward to the left and right ends of the cross tubes.
It is characterized by a pair of left and right backstays connected to the seat pillar tube.

[Function] According to this configuration, even though the main pipe and the seat pillar tube are made into one, the lower part of the backstay does not bend significantly toward the lower end of the seat pillar tube, and the backstay can be spaced apart. The width can be formed to be wide over the entire length.

Furthermore, since the cross tube also functions as a cross member that connects the left and right backstays, it is possible to increase the torsional rigidity and lateral rigidity of the entire frame compared to the past.

[Embodiment] The present invention will be explained below based on an embodiment shown in the drawings.

Reference numeral 1 in the figure indicates a steering head vibe, and a main pipe 2 extending rearward and a down tube 3 extending downward are welded to the rear surface of the steering head vibe 1.

Note that the welded portions of the steering head vibe 1, main pipe 2, and down tube 3 are connected to each other by a head vibe gusset 4.

The rear part of the main pipe 2 is bent downward to form a seat pillar tube 5, and an engine 8 is mounted between the lower end of the seat pillar tube 5 and the down tube 3. . Engine 8 of this embodiment
is a four-stroke single-cylinder engine, the front end of the crankcase 9 is connected to the lower end of the down tube 3 via the first engine bracket 1o, and the rear end of the crankcase 9 is connected to the second engine bracket 1o. The seat pillar tube 5 is connected to the lower end of the seat pillar tube 5 via an engine bracket 11 .

Therefore, the down tube 3 and the seat pillar tube 5 are connected by the crankcase 9, and the crankcase 9 serves as the negative part of the frame structure.

The second engine bracket 11 is welded to the lower end of the seat pillar tube 5, and includes a pair of left and right support walls 12 that extend forward and spaced apart from each other.

On the other hand, a pair of left and right seat rails 6 extending rearward are welded to the upper end of the seat pillar tube 5 via a bracket 7. Further, a cross tube 1 extending in the left-right direction is provided at the lower end of the seat pillar tube 5.
Approximately the middle portion of No. 3 is welded. This cross tube 13 has an axial length that approximates the intermediate width of the seat rail 6, and both ends thereof protrude beyond the support wall 12 of the second engine bracket 11 to the left and right sides, respectively.

A pair of left and right backstays 14 are installed between both ends of the cross tube 13 and the middle of the seat rail 6. The back stays 14 extend obliquely upward from both ends of the cross tube 13 in a straight line without being bent midway.
Rear arm brackets 15 extending forward are welded to the lower circumferential surfaces of the rear arm brackets 4 and 4, respectively. The rear arm bracket 15 is connected to the support wall 1 of the second engine bracket 11.
The front end of the rear arm 16 is swingably supported between the rear arm bracket 15 and the support wall 12 via a pivot shaft 17.

The rear arm 16 includes a pair of left and right arm members 18 that extend rearward, and a gusset 20 that connects the front parts of these arm members 18 to each other. The branch tube body 19 is welded.

The pivot structure of this rear arm 16 will be described with reference to FIG. A pivot shaft 17 inserted between the rear arm brackets 15 passes through the inside. The pivot shaft 17 has a nut 22 at its penetrating end.
The sleeve 23 is prevented from being removed by screwing it in, and a sleeve 23 is fitted around the outer periphery of the portion located between the collar 21 and the rear arm bracket 15. A pivot tube 19 at the front end of the rear arm 16 is rotatably fitted into the outer periphery of these sleeves 23 via a rubber bushing 24 and a collar 25.

Therefore, the rear arm 16 is disposed between the backstays 14, and the lower part of the backstay 14 passes outside each arm member 18.

Note that a footrest bracket 26 that supports a footrest for the driver (not shown) is attached to the outside of the rear arm bracket 15, and these footrest brackets 26 are collinear with the rear arm bracket 15 by the pivot shaft 17. .

Further, a seat 34 is supported on the seat rail 6. As shown in FIG. 1, this seat 34 is a two-person seat having a seating portion 34a for a driver and a seating portion 34b for a fellow passenger. The seat 34b for the driver is the seat 34b for the driver.
It is one step higher than 4a.

Both ends of a bracket 27, which is formed by bending a vibe material into a substantially U-shape, are welded to the middle of the backstay 14, which extends rearward and diagonally upward on the outside of the rear arm 16. A curved portion 27g of the bracket 27 projects behind the back stay 14, and a footrest stay 28 is welded to the rear surface of the curved portion 27a. These footrest stays 28 are provided with support metal fittings 29 having a U-shaped cross section.
is bolted. A rear foot rest 31 for a fellow passenger is pivotally supported on these support fittings 29 via bins 30 so that the rear foot rest 31 can be raised and lowered.
is located above the arm member 18 of the rear arm 16.

In the figure, the reference numeral 32 indicates a drive chain, and the reference numeral 33 indicates a reaction that suspends the rear end of the rear arm 16.

According to such a configuration, the steering head vibe 1
Since the main pipe 2 extending from the main pipe 2 and the seat pillar tube 5 connected thereto are one, the frame structure near the driver's seating position can be made narrower. Therefore, when the driver sits on the seat 34, the driver does not have to spread his or her legs wide apart, thereby being able to obtain an optimal riding posture and making it possible to reduce the weight of the frame.

Moreover, in this case, the middle part of the cross tube 13 having an axial length equivalent to the width of the seat rail 6 is welded to the lower end of the seat pillar tube 5, and both left and right ends of the cross tube 13 and the seat rail 6 are welded to the lower end of the seat pillar tube 5. Since the back stay 14 is installed over the middle of the seat pillar tube 5, the lower part of the back stay 14 does not bend significantly toward the lower end of the seat pillar tube 5. Therefore, the backstays 14 extend substantially linearly through the outside of the arm member 18 of the rear arm 16, and the distance between the backstays 14 can be widened over the entire length.

Moreover, since the cross tube 13 connecting the lower ends of the backstay 14 also functions as a cross member, the main pipe 2 and the seat pillar tube 5
Despite having only one rod, the torsional and lateral rigidity of the entire frame is improved.

Since the backstay 14 and the second engine bracket 11 are indirectly connected via the cross tube 13, the second engine bracket 11
Since the load from the backstay 14 is not directly applied to the second engine bracket 11, it is possible to prevent the load from being concentrated on the second engine bracket 11.

In addition, the rear arm brackets 15 are welded to the left and right back stays 14, and the pivot shaft 17 for pivotally supporting the rear arm 16 is passed between these rear arm brackets 15.
It also has the function of connecting. Therefore, the connection between the backstay 14 and the rear arm 16 is ensured, the frame rigidity is further improved, and a diamond-shaped frame with excellent strength balance can be obtained.

[Effects of the Invention] According to the present invention described in detail above, the lower part of the backstay does not bend significantly toward the lower end of the seat pillar tube, and the separation width of the backstay can be formed to be wide over the entire length. At the same time, the cross tube also functions as a cross member that connects the left and right backstays, so even though the main pipe and seat pillar tube are made into one, the torsional rigidity of the entire frame is lower than before. It is possible to increase the lateral rigidity and obtain a diamond-shaped frame with excellent strength balance.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, FIG. 1 is a side view of the entire frame, FIG. 2 is a plan view of the frame, and FIG. 3 is a side view showing the pivot portion of the rear arm to the frame. 4 is a sectional view taken along the line IV--IV in FIG. 3, and FIG. 5 is a sectional view taken along the line v--v in FIG. 3. 2... Main pipe, 3... Down tube, 5...
... Seat pillar tube, 6... Seat rail, 8
River engine, 13...cross tube, 14...backstay 16...rear arm.

Claims (1)

[Claims] A main pipe extending rearward and a down tube extending downward are connected to the head pipe, and the rear part of the main pipe is guided downward to form a seat pillar tube. In a diamond-shaped frame of a motorcycle in which the front and rear parts of an engine are connected between the lower end and the lower end of the down tube and the engine is used as a part of the frame structure, the main pipe and the A continuous seat pillar tube is used as one, and a pair of left and right seat rails extending rearward are connected to the rear of this main pipe, and at the lower end of the seat pillar tube, approximately the middle part of a cross tube extending in the left and right direction is connected. A diamond-shaped frame for a motorcycle, characterized in that a pair of left and right back stays are connected to the left and right ends of the cross tube, and are connected to the left and right end portions of the cross tube, which extend rearward and diagonally upward and are connected to the seat pillar tube.