JPH0573630B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to frame structures for vehicles including motorcycles, tricycles, and the like.

For example, the frame that forms the skeleton of a motorcycle is not only sturdy but also has a certain degree of flexibility.
Moreover, requirements such as being lightweight and thin are desired. The so-called double cradle type frame shown in Fig. 1 is one of the typical ones, and the head pipe 1 into which the front fork of the front wheel is fitted and supported, and the rear fork 3 (swing arm) of the rear wheel swing. Pivot bearing 2 that is freely supported
An important point in frame design is how to connect these with rigidity and provide a lightweight frame structure.

However, in the case of the double cradle type frame shown in Fig. 1, the casing is formed from square steel pipes or round steel pipes as shown in the figure, and welding is often used as the main assembly method, resulting in a very high manufacturing cost. We are burdened with a destiny.

The structural problem is that the Prolink rear suspension R/S is often connected to a cross reinforcing member, and the rear suspension R/S
In some cases, this operation caused large stresses in the frame structure, which was extremely disadvantageous.

The present invention was made in view of the circumstances surrounding the conventional frame structure, and its purpose is to provide a frame structure that has the desired rigidity, is lightweight, and ultimately significantly reduces the number of manufacturing steps. An object of the present invention is to provide a frame structure for a straddle type vehicle.

In the vehicle frame structure according to the present invention,
A pair of main frames linearly connects a head pipe that rotatably supports the front fork and a pivot bearing that swingably supports the rear fork, and a main frame linearly connected to the rear upper surface of the main frame and extending rearwardly upward. a pair of plate-shaped rear frames having a slope portion formed to gradually approach the slope portion and a parallel portion extending approximately parallel to the slope portion; and a slope portion of each of the pair of plate-shaped rear frames. A cross member is provided at a position where the extension surfaces pass over the intersecting ridge lines and straddles the parallel region, and an upper end connecting portion of the rear suspension is provided approximately in the center of the cross member. It is a feature.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, frame structures of vehicles, particularly motorcycles including tricycles, which are embodiments of the present invention will be described in detail with reference to the drawings. In FIG. 2, 4 indicates a main frame, and 5 indicates a rear frame. A pair of main frames 4 are provided along both the left and right sides of the vehicle body, and have a panel structure, so that the main frames 4 are substantially linear when viewed from the side in the direction of arrow A, that is, a head pipe into which a front fork (not shown) is fitted. 6 and a pivot bearing 7 that swingably supports the spear fork 8. The line connecting the pivot bearing 7 is substantially straight.

What this means is that while the usual method of dealing with external forces acting on the car body from all angles has been to adopt a housing frame structure made of square steel pipes as shown in Figure 1, The idea is to reduce the number of members on each side of the skeleton that share the role as much as possible and make it into a single member. The most efficient direction for consolidating each member into a single member is to construct members on a line connecting the pivot bearing 7 of the head pipe 6, which is the diagonal direction in this case. Therefore, in the case of the embodiment, the main frame 4 has a structural design that can withstand external forces acting from all angles.

The configuration of each panel of the pair of main frames 4 is as follows:
As shown in Fig. 3, plates _4a1 and _4a2 are press-formed as outer plates using not only thin steel plates or aluminum but also synthetic resins such as FRP and CFRP to form a tube with a rectangular cross section. The internal space is formed as a structure filled with honeycomb cores 9 which are separated into a number of mutually independent chambers. Specifically, by filling the honeycomb core 9 as shown in the figure and using it as a reinforcing member, it is possible to cope with the external force acting particularly from the direction of the arrow A, and the entire panel is lightened and has the necessary cross-sectional performance. This is where you have. That is, the isolated holes 9a of the honeycomb core 9 consisting of independent chambers are connected to the plate 4.
By filling substantially perpendicularly to the inner walls of each of a ₁ and 4a ₂ , we aim to achieve the effect of exhibiting the unique load-bearing strength of a honeycomb member. In this case, it is assumed that the plate 4a ₁ and the plate 4a ₂ are caulked together using a pot rivet 10.

As mentioned above, when the structure of the panel 4a is press-formed to have a rectangular cross section with different aspect ratios, if we consider this as a single beam structure, the width bm/m and the height hm/m will be b<h. Regarding the relationship, arrow A
It is necessary to strengthen the cross-sectional performance of the member against horizontal forces caused by Thus, by utilizing the characteristics of the honeycomb member that has a high resistance to external forces, mainly compressive force, acting in the direction of the spaced holes 9a of the honeycomb core 9, this is employed as the reinforcing member of the panel 4a. Therefore, as shown in FIG. 3, the partition holes 9a are filled so as to be perpendicular to the long sides of the plates 4a ₁ and 4a ₂ .

In addition, as the honeycomb core 9, the spaced holes 9
It is also clear from the standpoint of buckling stress that the shorter the length in the a direction, the higher the rigidity of the reinforcing member. Therefore, as shown in FIG. 4, the interior space of the panel 4a is partitioned in various directions, and each compartment is filled with rectangular honeycomb cores 9. That is,
In the case of Figure a, the panel cross section is divided by the partition plate 4a ₃ , and the chambers 4a ₄ , 4a ₄ are separated along the longitudinal direction of the panel.
are separated. As a result, the separated chamber 4a ₄
If the frontage cross section has a width b ₁ m/m and a height h ₁ m/m and b ₁ > h ₁ , short and small honeycomb cores 9 as shown are placed vertically and filled. It turns out. The same reasoning applies to figures b, c, and d of the same figure, so a description thereof will be omitted.

On the rear upper surface of the main frame 4, near the pivot bearing 7, a pair of left and right plate-shaped rear frames 5, which have the appearance of tail wings for attaching seats, etc., are arranged so as to straddle the panels 4a, 4a on both sides.
In addition, they are connected over a long area. These rear frames 5 are also configured to have a panel structure by press molding, and the front hem portions of both rear frames 5 are reinforced by horizontally connecting the upper surfaces of the intermediate portions of each panel 4a of the main frame 4. It is also connected and fixed to a cross member 12 serving as an auxiliary frame. The bottom portion is caulked or bolted to the upper surface of each panel 4a of the main frame 4 using pot rivets (not shown). Further, although each rear frame 5 has a structure that is slightly thinner than the panel 4a of the main frame 4, the inside thereof is still filled with a honeycomb core. Both rear frames 5 are arranged in a V-shape when viewed from the rear with their legs widening, that is,
They are formed as a pair of plate-shaped rear frames having a slope portion 5a that gradually approaches each other upward and a parallel portion 5b that extends approximately parallel to the slope portion. The main frame side panels 4 are spaced apart by the symbol W, and the stress acting on both rear frames forms the base of a triangle.
It acts on a and 4a from the inside diagonally upward, that is, from the vertex direction of the triangle.

As described above, the mutually proximate portions of the pair of plate-shaped rear frames 5 forming an isosceles triangle with the base W, that is, the slope portions 5 of each of the pair of plate-shaped rear frames
The cross member 1 is located at a position where the extended surface of a crosses the ridgeline 5L and in the area of the parallel portion 5b.
5 are straddled. And this cross member 1
The upper end connection part of the rear suspension is provided approximately in the center of the frame 5, and the Prolink suspension R/S
The cushion unit is fastened with bolts. That is, the main frame 4 of both rear frames 5
If the joining length is L, then the rear suspension R/S is suspended at the apex of a square pyramid whose vertical and horizontal bases are this L and the width W between the frames. .

The above configuration is suitable not only for application to frame structures for straddle-type vehicles such as motorcycles, but also for chassis of various vehicles such as agricultural machines. In the case of the example structure, the degree of freedom in design is not only increased by adapting to the external load force acting on the main frame, in other words, by selecting the aspect ratio and the number of partition plates for each vehicle rank. ,
The aim is to simultaneously increase rigidity and reduce weight, ultimately leading to significant cost reductions.

As detailed above, in the vehicle frame structure according to the present invention, a pair of main frames linearly connect a head pipe that rotatably supports a front fork and a pivot bearing that pivotally supports a rear fork in a side view. and a pair of plates having a slope portion linearly connected to the rear upper surfaces of the pair of main frames and formed to gradually approach rearward and upward, and a parallel portion extending substantially parallel to the slope portion. A cross that passes on a normal line located at the center of the linearly connected joint part in the intersection area on the extension line of the slope parts of the pair of plate-like rear frames and the pair of plate-like rear frames, and is provided in the parallel part area. Because of the structure, which includes a cross member and an upper end connecting portion of the rear suspension provided approximately at the center of the cross member, the reaction load caused by the operation of the rear suspension is supported at the apex of the triangle. As a result, the most structurally stable stress balance can be obtained throughout the frame structure, and the rigidity of the frame can be increased without causing concentrated stress in a single member or increasing the weight of the frame structure.

Further, as described above, in the frame structure according to the present invention, since the mutually adjacent adjacent parts (parallel parts) of the rear frames, that is, the rear suspension mounting parts are connected to each other by the cross member, the rear suspension mounting parts are connected to each other by the cross member. The rigidity is extremely high.

Furthermore, by using a single cross member to serve both as a member for supporting the connecting portion of the rear suspension and as a member for increasing the rigidity of the rear frame, it is possible to increase the rigidity and reduce the number of parts, thereby reducing weight.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a double cradle type frame structure, FIG. 2 is a perspective view showing an example structure of the present invention, FIG. 3 is a partial perspective sectional view showing the main frame panel structure, and FIG. Figures a, b, c,
d is a perspective sectional view showing the structure of the panel embodiment of the main frame. Explanation of symbols of main parts, 4...Main frame, 5...Rear frame, 5a...Slope part, 5b
...Parallel part, 5L...Ridge line, 4a...Panel, 4
a ₁ , 4a ₂ ... Outer panel, 4a ₃ ... Partition plate, 4a ₄ ...
Separate chamber, 6... Head pipe, 7... Pivot bearing, 9... Honeycomb core, 9a... Separate hole.

Claims (1)

[Scope of Claims] 1. A pair of main frames linearly connecting a head pipe that rotatably supports a front fork and a pivot bearing that swingably supports a rear fork, and a rear part of the pair of main frames. A pair of plate-shaped rear frames having a slope portion formed to extend gradually closer to the rear and upper side from the upper surface over a long region L, and a parallel portion extending substantially parallel to the slope portion. a cross member disposed astride the parallel region at a position where the extended surfaces of the slope portions of each of the pair of plate-shaped rear frames intersect, and a substantially central portion of the cross member. 1. A frame structure for a vehicle, comprising: an upper end connecting portion of a rear suspension provided in the frame structure.