JPH10100976A - Body frame for motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enlarge the area of a pressure receiving face by a deformed part so as to be able to disperse stress by interposing the deformed part of another pipe constituting a part of a body frame, between a cross pipe and each of a pair of pipes. SOLUTION: The tips of a cross pipe 21 laid between tank rails 17, 17 are butt-welded to deformed parts 32 welded to the tank rails 17, that is, the cross pipe 21 is horizontally laid across a pair of tank rails 17, 17 with the deformed parts 32 interposed between. With the deformed part 32 thus interposed at a connection part between each tank rail 17 and the cross pipe 21, the area of a pressure receiving face at the time of the mutual force of the tank rail 17 and cross pipe 21 being transmitted becomes large compared to the case of welding the cross pipe 21 directly to the tank rail 17, and stress generated to the connection part is dispersed through the deformed part 32 so as to be able to obtain a motorcycle body without stress concentration on the connection part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorcycle frame having a pair of pipes and a cross pipe.

[0002]

2. Description of the Related Art Conventionally, a motorcycle body frame has a tank rail welded to a head pipe so as to form a pair in the vehicle width direction of the vehicle body, and a cross pipe is laid horizontally between the tank rails. There is. In this type of body frame, a reinforcing plate may be interposed between the tank rail and the cross pipe in order to bridge the cross pipe between the tank rails.

[0003] This is because, when a relatively thin cross pipe is welded to the side surface of the tank rail, stress tends to concentrate on the connecting portion between the tank rail and the cross pipe. A reinforcing plate having a larger area than the end surface of the cross pipe is welded to the side surface, and the end surface of the cross pipe is abutted on the reinforcing plate and welded. By employing this configuration, the area of the pressure receiving surface is increased, and the stress is easily dispersed.

When the reinforcing plate is not used as described above, the stress is dispersed by increasing the thickness of the tank rail or increasing the diameter of the cross pipe.

[0005]

However, in order to prevent stress from being concentrated on the connecting portion between the tank rail and the cross pipe, a reinforcing plate is used as described above, the thickness of the tank rail is increased, or the cross pipe is not used. When the diameter is formed large, the weight of the vehicle body frame is increased by the amount of adopting this configuration, and the manufacturing cost is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is possible to prevent stress from being increased in weight and cost while concentrating stress on a connecting portion between a pair of pipes and a cross pipe. It is an object of the present invention to provide a body frame for a motorcycle having no vehicle.

[0007]

According to a first aspect of the present invention, there is provided a motorcycle body frame in which one end of a pipe other than a pair of pipes and a cross pipe is plastically deformed into a plate shape. The cross-pipe is welded to mutually facing surfaces of the pipe, and the tip of the cross pipe is welded to this deformed portion. According to the present invention, a deformed portion of another pipe constituting a part of the vehicle body frame is interposed between the pair of pipes and the cross pipe, and the deformed portion increases the area of the pressure receiving surface and disperses the stress. I do. Therefore, in preventing the stress from being concentrated on the connecting portion between the pair of pipes and the cross pipe, another member (reinforcing plate) other than the body frame pipe does not need to be interposed in the connecting portion. In addition, the pair of pipes and the cross pipe can have a structure that can obtain the minimum rigidity required for forming the body frame.

A motorcycle body frame according to a second aspect of the present invention is the motorcycle body frame according to the first aspect, wherein a pair of pipes is formed by a tank rail extending from a head pipe, and a pipe having a deformed portion is provided. It consists of a pair of down tubes welded to the head pipe. According to the present invention, the deformed portion of the down tube is interposed at the connecting portion between the tank rail and the cross pipe,
The rear ends of the pair of down tubes are also connected by a cross pipe. Therefore, both the tank rail and the down tube can be reinforced by one cross pipe.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a motorcycle body frame according to the present invention will be described below in detail with reference to FIGS. FIG. 1 is a side view of a motorcycle employing a vehicle body frame according to the present invention, FIG. 2 is a side view showing a tank rail portion of the vehicle body frame, FIG.
Is a cross-sectional view taken along the line IV-IV in FIG. 2, and FIG.
FIG. 6 is a perspective view of a main part, taken along a line V-V.

In these figures, reference numeral 1 denotes a motorcycle according to this embodiment. The motorcycle 1 includes a cowling 2 at a front portion of a vehicle body, and employs a structure in which a water-cooled two-cycle engine 3 drives a rear wheel 4. Reference numeral 5 denotes a front wheel of the motorcycle 1, reference numeral 6 denotes a front fork, and reference numeral 7 denotes a steering handle. 8 is a fuel tank, 9 is a seat,
Reference numeral 10 denotes a radiator, 11 denotes a rear arm, and 12 denotes a rear cushion unit. The rear arm 11 is connected via a pivot shaft 15 to a rear arm bracket 14 of a body frame 13 described later.

The vehicle body frame 13 includes a head pipe 16 for rotatably supporting the front fork 6, and a tank rail 17 extending downward from the head pipe 16.
And a down tube 18, the rear arm bracket 14 connected to the rear end of the tank rail 17, a seat rail 19 and a back stay 20. The head pipe 16 in the body frame 13
As shown in FIG. 3, the other components are provided in pairs in the left-right direction of the vehicle body, and the left and right components are connected to each other via cross pipes 21 to 24.

The cross pipe 21 includes the left and right tank rails 1.
7, the cross pipes 22 and 23 connect the left and right rear arm brackets 14, and the cross pipe 24 connects the left and right seat rails 19.
2, the cross pipes 21 to 23 are provided with engine support brackets 25 to 27, and the cross pipes 23 and 24 are provided with cushion brackets 28 for pivotally supporting the upper end of the cushion unit 12. It is spanning. The down tube 18, the seat rail 19, and the back stay 20 are each formed of a tube having a circular cross section.

The tank rail 17 is formed of a square pipe formed by bending a flat plate made of steel, and as shown in FIG. 5, the base end and the end of the flat plate are joined by butt welding. . In FIG. 5, the welded portion is indicated by reference numeral 17a. In addition, this welding part 17a
The outer bead protruding from the outer surface of the tank rail 17 is removed by grinding.

The tank rail 17 has its front end welded to the head pipe 16 and its rear end welded to the square hole 29 of the rear arm bracket 14 as shown in FIG. . The rear arm bracket 14 is formed by fitting the outer half portion 14a of the vehicle body to the inner half portion 14b of the vehicle body and welding portions overlapping each other.
The tank rail 17 and the back stay 20 are welded to the upper part in a so-called middle shape. Tank rail 1
The rear arm bracket 7 is not affected by the presence of the inner bead by being fitted into the square hole 29 of the rear arm bracket 14 as described above, although the inner bead formed in the manufacturing process remains inside. 14 can be accurately assembled.

As shown in FIG. 4, a cylindrical boss 30 having a relatively small diameter is provided on the rear arm bracket 14 at a portion where the back stay 20 is welded to the rear arm bracket 14. In this case, the back stay 20 is fitted so that the front end thereof comes into contact with the main part of the rear arm bracket 14. The tank rail 17 is attached to the rear arm bracket 14 by the connection structure described above.
By connecting the backstay 20 and the backstay 20, the position of the rear arm bracket 14 with respect to the backstay 20 is determined, and the position of the tank rail 17 is determined by adjusting the fitting allowance with the rear arm bracket 14. Therefore, these three members can be combined easily and accurately.

As shown in FIGS. 2 and 3, the down tube 18 has a front end welded to a portion of the head pipe 16 below the tank rail welding portion, and a rear end welded to the tank rail 17. doing.
The reference numeral 31 provided at the front end of the down tube 18 is a reinforcing pad. The rear end of the down tube 18 is plastically deformed into a plate shape as shown in FIG.
Opposite side surfaces 1 of a pair of tank rails 17, 17
7b is welded. Reference numeral 3 denotes the deformed part.
Indicated by 2.

The tip of the cross pipe 21 bridged between the tank rails 17 and 17 is welded to the deformed portion 32 welded to the tank rail 17 as described above. In other words, the cross pipe 21 is laid horizontally on the pair of tank rails 17 with the deformed portion 32 interposed between the cross pipe 21 and the tank rail 17. The dimensions of the deformable portion 32 in the up-down direction and the front-back direction are set to be sufficiently larger than the outer diameter of the cross pipe 21.

When the deformed portion 32 is interposed at the connecting portion between the tank rail 17 and the cross pipe 21, the tank rail 1
7 when the force is transmitted from the cross pipe 21 to the cross pipe 21 or when the force is transmitted from the cross pipe 21 to the tank rail 17, the area of the pressure receiving surface is larger than when the cross pipe 21 is directly welded to the tank rail 17. Become. For this reason,
The stress generated in the connecting portion is dispersed through the deformed portion 32.

Therefore, a structure in which stress is prevented from being concentrated on the connecting portion between the pair of tank rails 17 and the cross pipe 21 can be realized by using the down tube 18 which forms a part of the body frame 13. it can. Moreover, the tank rail 17 and the cross pipe 21 are
It is possible to adopt a structure in which a minimum rigidity required for forming the third member 3 is obtained. That is, in order to avoid concentration of stress on the connecting portion, it is not necessary to set the thickness of the tank rail 17 to be unnecessarily thick or to set the diameter of the cross pipe 21 to be unnecessarily large.

When the down tube 18 is used to avoid stress concentration at the connecting portion, the rear ends of the pair of down tubes 18 are connected by the cross pipe 21. Both the rail 17 and the down tube 18 can be reinforced.

In this embodiment, the tank rail 1
7 is connected to the cross pipe 21 by a down tube 1
Although the example in which the deformed portion 32 of FIG. 8 is interposed has been shown, the seat rail 19 can be interposed instead of the down tube 18. If this configuration is adopted, the seat rail 19
Is plastically deformed into a plate shape, and this deformed portion is interposed between the tank rail 17 and the cross pipe 21.

The first invention can also be applied to a connecting portion between the pair of seat rails 19, 19 and the cross pipe 24. In this case, it is conceivable that a plate portion corresponding to the deformed portion is provided on the cushion bracket 28 and this plate portion is interposed in the connecting portion.

[0023]

As described above, according to the first aspect, a deformed portion of another pipe constituting a part of the body frame is interposed between the pair of pipes and the cross pipe, and the deformed portion is Since the area of the pressure receiving surface becomes large and the stress is dispersed, in order to prevent the stress from being concentrated on the connecting portion between the pair of pipes and the cross pipe, another member (reinforcement plate) different from the body frame pipe is used. It is not necessary to intervene in the connecting portion. Moreover, the pair of pipes and the cross pipe are
It is possible to adopt a structure that can obtain the minimum rigidity required for forming the body frame. Therefore, it is possible to obtain a body frame for a motorcycle in which stress is not concentrated on the connecting portion between the pair of pipes and the cross pipe while preventing weight increase and cost increase.

According to the second aspect of the present invention, the deformed portion of the down tube is interposed at the connecting portion between the tank rail and the cross pipe, and the rear ends of the pair of down tubes are connected by the cross pipe. A cross pipe can reinforce both the tank rail and the down tube. Therefore, not only stress concentration at the connecting portion between the tank rail and the cross pipe can be avoided, but also a highly rigid body frame can be obtained.

[Brief description of the drawings]

FIG. 1 is a side view of a motorcycle employing a vehicle body frame according to the present invention.

FIG. 2 is a side view showing a tank rail portion of the vehicle body frame.

FIG. 3 is a plan view showing a tank rail portion of the vehicle body frame.

FIG. 4 is a sectional view taken along line IV-IV in FIG. 2;

FIG. 5 is a sectional view taken along line VV in FIG.

FIG. 6 is a perspective view of a main part.

[Explanation of symbols]

13 ... body frame, 17 ... tank rail, 18 ... down tube, 21 ... cross pipe.

Claims (2)

[Claims] In a motorcycle body frame having a pair of pipes and a cross pipe between these pipes, one end of another pipe different from the two pipes is plastically deformed into a plate shape, and this deformed portion is formed. A body frame for a motorcycle, characterized in that the pair of pipes are welded to opposing surfaces and a tip of the cross pipe is welded to the deformed portion. 2. The motorcycle body frame according to claim 1, wherein the pair of pipes is constituted by a tank rail extending from a head pipe, and the pipe having a deformed portion is
A body frame for a motorcycle, comprising a pair of down tubes welded to a head pipe.