JPH0569873A - Body frame for motorcycle - Google Patents

Abstract

PURPOSE:To omit a head pipe from a steering head part. CONSTITUTION:A steering head 1 is formed into an almost triangle pole shape, comprising upper and lower plates 20, 21 of almost triangle shape as viewd by plane and a side plate 22 of connecting these plates vertically to surround an external side surface, to form bearing parts 24, 25 in each front part of the upper and lower plates 20, 21, and a steering shaft 4 is turnably supported through bearings 26, 27 fitted to these bearing parts. A central rib 28 of vertically connecting the upper and lower plates 20, 21 is provided behind the bearing parts 214, 25 to reinforce a total unit of the steering head l so that the steering shaft 4 can be supported.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle body frame of a motorcycle, and more particularly to a vehicle body frame provided with a steering head portion having a novel structure.

[0002]

2. Description of the Related Art As a body frame structure for a motorcycle,
A steering head having a substantially triangular shape in plan view is provided at the front end of the main pipe, and the front ends of main pipes that are paired left and right are connected to the bottom side of the steering head, and rear forks are provided at the rear ends of the main pipes. In addition to fixing the pivotally supported rear fork bracket, a head pipe is provided at the front part corresponding to the triangular top of the steering head.
As an example, it is described in Japanese Utility Model Laid-Open No. 61-3091. This steering head is made of a light alloy that is cast and forged in a substantially triangular prism shape, and is manufactured by integrally inserting a head pipe that has been separately manufactured in advance and subjected to predetermined machining at the time of molding. This head pipe rotatably supports a steering shaft that constitutes a steering mechanism via bearings fitted to the upper and lower open ends. Separately from this, a head pipe and a main pipe are welded together, and a head pipe gusset and a main pipe gusset are welded between them to reinforce each other.

[0003]

In the former structure, the steering head is required to have a considerably high rigidity in order to support the steering mechanism. Therefore, the head pipe is indispensable as means for improving the rigidity. However, in the case of a type in which the head pipe is integrally cast and forged, it is necessary to manufacture the head pipe and then insert-mold it. Therefore, the number of manufacturing processes is large and the molding is troublesome and the head pipe is used. The number of parts is large, and the structure of the steering head is likely to be relatively complicated and the weight is likely to increase. Further, in the case of the latter structure, since a plurality of gussets are required, the number of parts increases, and the welding length of these gussets increases, so that the number of welding steps increases. Moreover, the product may be deformed due to the thermal strain caused by welding. Then, this invention aims at solving the problem which concerns.

[0004]

In order to solve the above problems, in a vehicle body frame of a motorcycle according to the present invention, a steering head having a supporting portion for pivotally supporting a steering mechanism has a substantially triangular shape in a plan view. A pair of upper and lower plates and side plates that connect the entire peripheral surfaces of the upper and lower plates to each other, and a bearing that forms a support portion of the steering mechanism is provided at each front part of the upper and lower plates. At the same time, a reinforcing member for connecting the upper plate and the lower plate is provided behind the bearing.

[0005]

[Operation] The steering head has a substantially triangular prism shape,
In addition, since the bearings that form the support portion of the steering mechanism are formed at the front portions of the upper plate and the lower plate, there is no conventional head pipe. Further, since the upper plate and the lower plate are connected to each other behind the bearing by the reinforcing member, the rigidity of the steering head is increased and the steering mechanism can be supported by the entire steering head, so that the head pipe can be omitted.

[0006]

EXAMPLE One example is shown in FIGS. FIG. 1 is a view showing a steering head of the embodiment in a central cross section, FIG. 2 is a view showing a plan view of the same in a half cross section, and FIGS. 3 to 5 are simplified horizontal cross sections for explaining a reinforcing structure. FIG. 6 is a left side view of the skeleton of the motorcycle using this embodiment, FIG. 7 is a right view of the same, FIG. 8 is a right rear view of the same, and FIG. 9 is a plan view of FIG. 11 is a view showing the same bottom shape, and FIG. 11 is a view showing the same rear view shape.

First, a schematic structure of a vehicle body frame will be described with reference to FIGS. 6 to 9. This vehicle body frame is formed by connecting a steering head 1 having a substantially triangular prism shape (see FIG. 8) provided at a front end portion, a main pipe 2 at an intermediate portion, and a rear fork bracket 3 at a rear portion, respectively, and integrally forming the steering head. The rear fork bracket is a cast product of aluminum alloy, and the main pipe is an extruded product of aluminum alloy.

A steering shaft 4 is vertically pierced at a front end portion of the steering head 1 and is pivotally supported by the steering shaft 1.
Top bridge 5 and bottom bridge 6 above and below the front end of the
Is supported. Front forks 7 are supported on the left and right of each bridge, a handle 8 is attached to the upper parts of the left and right front forks 7, and a front wheel 9 is supported between both lower ends. The steering shaft 4, the top bridge 5, the bottom bridge 6, the front fork 7, the steering wheel 8 and the front wheels 9 constitute a steering mechanism for the front wheels.

The main pipe 2 is a well-known hollow member that extends in the front-rear direction to make a pair on the left and right (see FIG. 9), and its front end portions are mounting legs formed on the left and right rear portions of the steering head 1 as described later. Connected to 10. A radiator 11 is provided below the main pipe 2, and a V-type two-cylinder two-cycle engine 12 is supported behind the radiator 11. A fuel tank 13 is supported in the front part above the main pipe 2, and a seat rail 14 extends rearward from the middle part. Further, a mountain-shaped cushion mounting stay 15 is provided on the right side of the rear portion, and an upper end portion of a cushion 16 forming a rear suspension is pivotally attached to the top portion of the stay 15.

The rear fork brackets 3 are paired left and right and are provided in the up-down direction (see FIG. 11). The upper ends of the rear fork brackets 3 are connected to the rear ends of the left and right main pipes 2, respectively, and are provided in the middle thereof. The rear fork 18 is attached to the pivot part 17
The front end of the is pivoted. The rear fork 18 is a known cantilever type. However, the arm portion 18 of the rear fork 18
The a is arranged on the right side of the rear wheel 19 (see FIGS. 9 and 10), and the rear wheel 19 is supported on the left side of the rear end of the arm portion 18a. Further, the cushion 1 is provided in the middle of the arm portion 18a.
The lower end portion of 6 is pivotally mounted, and the cushion 16 is disposed substantially along the arm portion 18a in plan view and is offset to the right side of the vehicle body (FIG. 9).

Next, the details of the steering head 1 will be described with reference to FIGS. As is apparent from FIGS. 1 and 2, the steering head 1 includes an upper plate 20 and a lower plate 2.
1 and a side plate 2 that covers the entire circumference of the upper plate 20 and the lower plate 21
2 is a hollow member cast into a substantially triangular prism shape,
The upper plate 20 has a substantially triangular shape in a plan view, and the lower plate 21 has the same shape. However, the steering head 1 can be manufactured not only by casting but also by welding a pressed plate-shaped member, and can be forged depending on the structure. Further, a shaft hole 23 penetrating the front portion of the steering head 1 in the vertical direction is formed at the front portions of the upper plate 20 and the lower plate 21 corresponding to the vertices of the triangles, and surrounds the upper and lower openings. Bearing portions 24 and 25 are formed. Bearings 26 and 27 are fitted into the bearings 24 and 25, respectively, and the steering shaft 4 can be rotatably supported via the bearings 26 and 27 (see FIG. 1).

A central rib 28 is provided at the rear of each bearing 24, 25.
Are linked up and down by. The central rib 28 is an example of a reinforcing member in the present application, and extends from the bearing portions 24 and 25 in the central portion of the steering head 1 to the rear side to form the upper plate 2.
0 and the lower plate 21 to connect the steering head 1
Is integrally formed during casting.

Mounting legs 10 are formed so as to project rearward from both sides of a rear portion corresponding to the bottom of the triangle in a plan view, and fitting portions 29 projecting further rearward are formed at each rear end portion in a stepped manner. The front end of each main pipe 2 is fitted to this,
It is welded at the joint along the step 30. In addition, this step 3
The shape of 0 may be oblique or straight, and preferably, the main pipe 2 can be connected straight without bending. An opening 31 is formed at the bottom of each mounting leg 10. Further, boss portions 32 and 33 for attaching various stays and the like are integrally formed on the side plate 22 during casting.

3 to 5 illustrate the steering head 1 in order to explain various ways of providing reinforcing members such as the central rib 28.
It is a figure which shows the plane cross section of FIG. First, FIG. 3 shows a rib structure similar to that of FIG. 2, in which one central rib 28 extends in the center direction of the vehicle body, and its front end portion has bearing portions 24, 25.
A relatively long arcuate portion 34 is integrally formed along the periphery of (only the 25 side is visible in this figure. The same applies hereinafter). The circular arc portion 34 constitutes a wall portion as a bearing holder. In FIG. 4, the center rib 28 is made slightly smaller, but side ribs 35 are integrally formed so as to project from the left and right side plates 22 so that each end portion extends along the circumference of the bearing portions 24, 25. The side ribs 35 also naturally extend in the vertical direction and connect the upper plate 20 (FIG. 1) and the lower plate 21. In FIG. 5, two central ribs 28 are provided and side ribs 35 similar to those in FIG. 4 are provided. As described above, the reinforcing members such as the central ribs 28 and the side ribs 35 are designed so that the shape, size, number, and position can be freely changed according to the required rigidity of the steering head 1.

The body structure will be further outlined with reference to FIG. 6 and subsequent figures. Each cylinder of the two-cycle engine 12 is arranged so as to open upward and downward toward the front, and the upper exhaust pipe 36 and the lower exhaust pipe 37 extending from each cylinder wrap around from the front of the two-cycle engine 12 to the lower side. Postpone. Of these, the large-diameter chamber 36a of the upper exhaust pipe 36 is 2
A thin rear exhaust pipe 36b located below the cycle engine 12 is a cushion disposed on the right outside of the arm portion 18a of the rear fork 18 and on the right side of the vehicle body between the cushion mounting stay 15 and the rear fork 18. 16 crosses diagonally upwards on the outside of 16 and
It is connected to the silencer 38 on the upper right side of (Fig. 8).
On the other hand, the lower exhaust pipe 37 has a large-diameter chamber 37a arranged in a space formed on the left side of the curved portion provided on the arm portion 18a of the cantilever type rear fork 18,
Further, the rear exhaust pipe 37b having the smaller diameter extends obliquely upward through the left side of the rear wheel 19 and is connected to the silencer 39 above the left side of the rear wheel 19.

As is apparent from FIGS. 8, 9 and 11, the seat rails 14 are provided as a left and right pair, but only the left side thereof is connected to the middle portion of the upper left side of the main pipe 2, and the right side thereof is the cushion mounting stay 15. Is not connected to the main pipe 2. Further, the lower portions of the respective reinforcement stays 40 provided obliquely downward from the rear portions of the left and right seat rails 14 are connected to only one central leg 41 so as to form a substantially Y shape when viewed from the rear (FIG. 11), The lower ends of the legs 41 are connected onto a cross pipe 42 (FIGS. 9 and 11) that is bridged between the left and right steering heads 1. Therefore, a space for disposing the cushion 16 is secured on the right side of the central leg 41. As is most apparent in FIGS. 7 and 8, reference numeral 43 is a drive sprocket and 44
Is a chain, and 45 is a driven sprocket, which are provided on the right side of the vehicle body. Further, in FIGS. 6, 7, 9 and 10, reference numeral 46 is a front cowl and 47 is a rear cowl.

Next, the operation of this embodiment will be described. 1 to 5, the steering head 1 has a substantially triangular prism shape including an upper plate 20, a lower plate 21, and a side plate 22, and an upper plate 2
Bearing portions 24 and 25 are formed at the front portions of the 0 and the lower plate 21, respectively. Therefore, the bearings 26 fitted to the bearings 24, 25,
The steering shaft 4 can be pivoted via 27. Further, since the central rib 28 and the side ribs 35 are appropriately provided, and the upper and lower ends thereof are arranged along the periphery of the bearing portions 24 and 25, and the upper plate 20 and the lower plate 21 are connected, The steering head 1 is reinforced by the central ribs 28 and the side ribs 35 to secure the required rigidity, and the steering shaft 4 can be supported by the entire steering head 1. Therefore, the conventional use of the head pipe can be omitted, the structure of the steering head 1 can be simplified, and the number of parts and the weight can be reduced. In particular, when the steering head 1 is cast as in this embodiment, the number of manufacturing steps is reduced and the molding is facilitated, which is advantageous in manufacturing. Also, when compared with the conventional structure in which the head pipe and the main pipe are welded and reinforced between the head pipe and the main pipe, these gussets are unnecessary because they are equivalent to those that integrate these gussets. In addition, the number of parts can be reduced, welding can be omitted, and further, the product quality can be improved by preventing the product from being deformed due to the thermal strain caused by the welding. Furthermore, since the shapes, sizes, numbers, positions, etc. of the central ribs 28 and the side ribs 35 can be arbitrarily set, the rigidity of the steering head 1 can be freely changed by appropriately providing these.
The degree of freedom in design is improved. The rear fork 18 is cantilevered, the cushion 16 is offset to one side on the right side of the vehicle body so as to overlap with the arm portion 18a, and the reinforcing stay 40 has a substantially Y-shape when viewed from the rear, so that the central leg 4 thereof is formed.
An arrangement space for the cushion 16 was secured on the right side of 1. Therefore, the large-diameter chamber 36a of the upper exhaust pipe 36 is connected to the lower exhaust pipe 37
Is arranged in front of the large-diameter chamber 37a to bring the small-diameter rear exhaust pipe 36b close to the outside on the right side of the arm portion 18a,
On the other hand, the large-diameter chamber 37a of the lower exhaust pipe 37 is connected to the arm 1
8a is disposed in the space formed by the curved portion on the left side, and the rear exhaust pipe 37b is passed outside the left side of the rear wheel 19. Therefore, the large-diameter chambers 36a, 37a of the upper and lower exhaust pipes 36, 37 can be arranged closer to the center of the vehicle body, and as a result, the vehicle body width can be made slim.

[0018]

According to the present invention, the steering head portion is formed into a substantially triangular prism shape, the steering shaft bearing is provided in front of the upper plate and the lower plate, and the upper plate and the lower plate are connected behind the bearing. A reinforcing member was provided. Therefore, the steering mechanism can be pivotally supported by the entire steering head, and the head pipe that was conventionally required can be omitted.
The structure of the steering head is simplified and the number of parts and weight can be reduced. Further, since the shape, size, number, position, etc. of the reinforcing member can be arbitrarily set,
By appropriately providing this, the rigidity of the steering head can be freely changed, and the degree of freedom in design is improved. In addition, particularly in the case of molding by casting or the like, the number of manufacturing steps is small and the molding is easy, which is advantageous in manufacturing. Further, since a plurality of gussets can be eliminated, the number of parts can be reduced and welding can be omitted, and further, the deformation of the product due to the thermal strain caused by the welding can be prevented and the quality of the product can be improved.

[Brief description of drawings]

FIG. 1 is a side sectional view of an essential part of an embodiment.

FIG. 2 is a view in which a substantial right half of an essential part of the embodiment is cut away.

FIG. 3 is a schematic plan sectional view of a main part of an embodiment.

FIG. 4 is a schematic plan sectional view of a main part of an embodiment.

FIG. 5 is a schematic plan sectional view of a main part of the embodiment.

FIG. 6 is a left side view of a skeleton part of a motorcycle to which an embodiment is applied.

FIG. 7 is a right side view of a skeleton portion of a motorcycle to which an embodiment is applied.

FIG. 8 is a perspective view from the right rear of the skeleton of the motorcycle to which the embodiment is applied.

FIG. 9 is a plan view of a skeleton part of a motorcycle to which an embodiment is applied.

FIG. 10 is a bottom view of the skeleton of the motorcycle to which the embodiment is applied.

FIG. 11 is a rear view of the skeleton of the motorcycle to which the embodiment is applied.

[Explanation of symbols]

 1 Steering Head 2 Main Pipe 3 Rear Fork Bracket 4 Steering Shaft 20 Upper Plate 21 Lower Plate 22 Side Plate 23 Shaft Hole 24 Bearing Part 25 Bearing Part 26 Bearing 27 Bearing 28 Central Rib (Reinforcing Member) 35 Side Rib (Reinforcing Member)

Claims (1)

[Claims] 1. A steering head having a support portion for pivotally supporting a steering mechanism for supporting front wheels is provided at a front end portion, and front ends of a pair of main pipes are connected to a rear portion of the steering head. In a vehicle body frame of a motorcycle in which a rear fork bracket for pivotally supporting a rear fork is fixed to each rear end portion of the vehicle, the steering head has a pair of upper and lower plates which are substantially triangular in a plan view, and these upper plates. And a side plate that connects the entire peripheral surface of the lower plate, and a bearing that forms a support portion of the steering mechanism is provided at each front portion of the upper plate and the lower plate, and the upper plate and the lower plate are connected behind the bearing. A vehicle body frame for a motorcycle, characterized in that a reinforcing member is provided.