JPS61238579A - Frame for motorcycle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to frames for motorcycles.

[Prior art]

In a frame in which an engine is mounted between left and right main pipes extending diagonally downward from the steering head pipe and a down tube extending rearward passing below the main pipes, the present applicant has recently developed a lightweight frame. In order to achieve both high rigidity, we proposed that the main pipe be constructed of a flat square pipe made of aluminum alloy whose vertical dimension is vertically elongated, and we have already filed a patent application in 1983.
The application has been completed as No.-156868.

[Problem that the invention seeks to solve]

However, in the frame of this prior art, the main pipe is formed to be longitudinally elongated as it advances forward, and the longitudinal dimension of the front end, which is the joint end with the steering head pipe, is formed to be approximately equal to the axial length of the head pipe. Therefore, it is extremely difficult to obtain a space for attaching the down tube to the steering head pipe, and there are problems such as moderate restrictions on the frame structure.

[Means for solving problems]

Therefore, in the present invention, when forming the longitudinal dimension of the front end portion of the main pipe to be approximately equal to the axial length of the steering head pipe, a cross member is passed between the front end portions of the main pipe, and the cross member is placed between the front end portions of the main pipe. A feature is that the upper end of the down tube is connected to the member.

[Effect]

According to this configuration, the rigidity around the steering head is ensured by the main pipe, so a space can be secured for attaching the down tube to this highly rigid part. Furthermore, since the downtube only needs to support the engine, its position relative to the steering head pipe is not so restricted, and therefore there is no problem in terms of strength, and the degree of freedom in frame configuration increases.

[Embodiments of the invention]

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

In the figure, reference numeral 1 denotes an aluminum alloy frame, and a steering head pipe 2 (hereinafter referred to as head pipe), which is vertically placed at a predetermined star angle at the front end of the frame, has a front fork 4 that pivotally supports a front wheel 3. It is pivotally supported. A pair of left and right main pipes 5, 5 are welded to the head pipe 2 and extend rearward and diagonally downward in a straight line as viewed from the side. The main pipes 5, 5 are as shown in FIG.
A pair of frame materials 6a and 6b, which are thin and have a cross-sectional road mouth shape with open sides, are welded against each other from the vehicle width direction, and the cross-sectional shape is flat and vertically elongated. It is formed into a rectangular cylinder shape. The vertical dimension of these main pipes 5.5 increases continuously as it advances toward the head pipe 2, and the vertical dimension of the front end opening that abuts against the head pipe 2 is the same as that of the head pipe 2. It is formed to be approximately equal to the axial length, and the front end opening is welded to the head pipe 2 over the entire circumference. Further, as shown in Fig. 2, the main pipes 5, 5 are expanded outward in the vehicle width direction immediately after the head pipe 2, and are bent from the middle so as to be parallel to each other, and remain rearward. A bracket 8 for pivotally supporting the rear arm 7 is welded to the rear end of the rear arm.

A rearwardly extending seat rail 9 is welded to the rear upper surface of the main pipe 5.5, and a backstay 10 is installed between the rear portion of the seat rail 9 and the bracket 8.

By the way, a cross member 11 made of an extruded aluminum alloy is spanned between the front ends of the main pipe 5.5. The cross member 11 crosses right and left behind the head pipe 2, and a down tube 12 is installed between the cross member 11 and the bracket 8.

The down tube 12 of this embodiment includes a pair of left and right front tubes 13.13 extending downward from the cross member 11, and a pair of left and right front tubes 13.13 extending rearward below the main pipe 5.5 from between the lower ends of the front tubes 13.13. An engine 15 is mounted in the space between the downch cove 12 and the main pipe 5.5. Note that square pipes made of aluminum alloy are used for the front tube 13, 13 and the rear tube 14.

Front tube 13. , 13 extends vertically on the front side of the engine 15, and has a boss portion 16° 16 welded to its upper end.
are abutted against the front surface of the cross member 11 and bolted. The lower ends of the front tubes 13 and 13 are connected by a cross pipe 17.
The crankcase 15a of the engine 15 is attached to the bracket 1.
9.19, and the front end of the rear tube 14 is welded.

The invasion tube 14 is attached to the crankcase 15a of the engine 15.
The boss part 22 welded to the rear end of the rear tube 14 is bolted to the cross member 18 connecting the lower ends of the brackets 8. It's tightened.

A radiator 2.degree. is installed on the front surface of the front tube 13.13, and exhaust pipes 21.21 led out from the engine 15 are inserted through the left and right sides of the front tube 14.

In addition, in the case of this embodiment, a wire 22 such as an accelerator wire or a choke wire is introduced from above between the front ends of the main pipe 5.5, as shown in FIGS. A harness 23, which is a bundle of various electrical cords, is introduced from below the pipe 2.

These wires 22 and harness 23 are connected to the head pipe 2
and the cross member 11, and after passing through the space 24, the wire 22 is pulled out below the main pipe 5.5 and routed toward the engine 15. After passing through the space 24, the harness 23 passes between the main pipes 5.5 and connects to the rear battery (
(not shown).

According to this configuration, the cross member 11 is hung between the front ends of the main pipe 5.5, and the front tube 13.13 of the down tube 12 is connected to this cross member 11, so that the main pipe 5.5 With the increase in the longitudinal dimension of
Even if it is difficult to obtain a space for mounting the down tube 12 on the head pipe 2, space for mounting the down tube 12 can be secured around the steering head.

In this case, since the vertical dimension of the front end openings of the main pipes 5, 5 is approximately equal to the axial length of the head pipe 2,
The joint area between the head pipe 2 and the main pipe 5.5 is increased, and the main pipe 5.5 ensures sufficient rigidity and strength around the steering head. Therefore, since the cross member 11 is located between the front ends of the highly rigid main pipes 5, 5, a space can be secured for attaching the down tube 12 to the highly rigid part, which improves strength. There is no problem at all.

Moreover, with this frame configuration, the down tube 1
2 only needs to support the engine 15, so there are no significant restrictions on its position with respect to the head pipe 2, and the above-mentioned attachment has the advantage of securing space and increasing the degree of freedom in frame construction.

Furthermore, since the down tube 12 of this embodiment has a single rear tube 14 that passes under the crankcase 15a, the spaces on both sides of the rear tube 14 are used as the insertion space for the exhaust pipes 21 and 21. can. Therefore, the exhaust pipe 21.21 can be easily routed, the exhaust pipe 21.21 can be brought closer to the inside of the vehicle body, and a sufficient bank can be secured.

Note that the structure of the down tube is not limited to the above embodiment, and there may be two down tubes on the left and right sides, or one down tube, and the installation thereof is not limited to bolting, but may be welded.

Furthermore, the material of the frame is not limited to aluminum alloy, and may be general steel.

〔Effect of the invention〕

According to the present invention described in detail above, it is possible to secure a space for installing the down tube in a highly rigid part, and there are no restrictions on the position of the down tube with respect to the steering head pipe, so the degree of freedom in designing the frame is increased. There are additional benefits.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and Fig. 1 is a side view of the 71 Norm, Fig. 2 is a plan view of the area around the steering head, Fig. 3 is a front view of the downtube, and Fig. 4 is a diagram showing the engine mounted on the frame. The front view of the loaded state, Figure 5 is v- in Figure 1.
A cross-sectional view taken along line v, and FIG. 6 is a side view of the motorcycle. 1... Frame, 2... Steering head pipe, 4... Front fork, 5... Main pipe,
11... Cross member, 12... Down tube, 1
5...Engine.

Claims (1)

[Scope of Claims] A steering head pipe arranged vertically in the vertical direction that pivotally supports the front fork, a pair of left and right main pipes led diagonally downward from the steering head pipe, and a main pipe that passes below the main pipe. In the frame of a motorcycle, which is equipped with a down tube that extends backwards, and an engine is mounted between the main pipe and the down tube, the main pipe is formed into a rectangular cylinder shape with a flat cross section and vertically elongated. The longitudinal dimension of the front end portion of this main pipe connected to the steering head pipe is formed to be approximately equal to the axial length of the steering head pipe, and a cross member is spanned between the front ends of these main pipes, and the cross member is A frame for a motorcycle, characterized in that the upper end of the down tube is connected.