JPH0764302B2 - Motorcycle body frame - Google Patents

Description

The present invention relates to a vehicle body frame of a motorcycle that is integrally formed by casting.

[Prior Art] Some vehicle body frames of motorcycles have a pair of left and right main frames connected to a head pipe surrounding a steering shaft, and a rear arm bracket for supporting a rear arm. The head pipe, the main frame and the rear arm bracket are made of pipe material having a circular or rectangular cross section, and these are welded and connected.

[Problems to be Solved by the Invention] As described above, the welding work of the head pipe, the main frame, and the rear arm bracket requires labor, and in the motorcycle, the weight reduction of the vehicle body and the reduction of the number of parts are required. It is conceivable to cast the body frame.

In this case, if the head pipe, the main frame, and the rear arm bracket are divided into two separate parts, the left and right parts, and the parts are integrally formed by casting, it is possible to use a mold whose mold depth does not change.
It is possible to suppress an increase in manufacturing cost.

By the way, when the head pipe, the main frame, and the rear arm bracket are divided into two parts, that is, the left and right bodies, and they are integrally formed by casting, it is important to integrally and simply join them. That is, the head pipe is a portion that supports the steering shaft, and the rear portion of the main frame is a portion that follows the rear arm bracket that supports the rear arm, and the load concentrates mainly on these portions. Corresponding joint structures are desired.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vehicle body frame of a motorcycle capable of easily and reliably improving the joint strength of a body frame that is split into left and right parts and integrally formed by casting. I am trying.

[Means for Solving the Problems] In order to solve the above problems, a vehicle body frame of a motorcycle according to the present invention includes a split steering shaft support portion that is divided into two parts on the left and right sides that surround a steering shaft, and each split steering shaft support. A pair of left and right main frame portions extending rearward from the vehicle body and a pair of left and right rear arm bracket portions extending downwardly from the rear of each main frame portion are integrally formed by casting of left and right light metal materials. Front and rear joint rib portions surrounding the steering shaft of the support portion are formed over substantially the entire length of the split steering shaft support portion, and the split steering shaft support portion abuts the front and rear joint rib portions to form the steering shaft of the steering shaft. A fastening member is inserted through the boss portions provided on the front and rear joining rib portions in the vehicle width direction to fasten the joint rib portion. A rear end portion of the pair of main frame portions is provided with a fastening member at the boss portion in the vehicle width direction via a bridge portion having boss portions at at least two positions which are separated by a predetermined distance in a substantially longitudinal direction of the main frame portions. It is characterized by being inserted through and fastened.

[Operation] In the present invention, the left and right split steering shaft support portions that surround the steering shaft, the pair of left and right main frame portions that extend rearward from the respective split steering shaft support portions, and the respective main frames Since a pair of left and right rear arm brackets extending downward from the rear of the section are integrally formed by casting of left and right light metal materials, the weight of the vehicle body frame and the number of parts can be reduced.

The split steering shaft support portion of the vehicle body frame abuts front and rear joining rib portions surrounding the steering shaft, and inserts a fastening member in a vehicle width direction into boss portions provided on the front and rear joining rib portions of the steering shaft. Are fastened and integrated. Since the joint rib portion of the split steering shaft support portion is formed over substantially the entire length of the split steering shaft support portion, a sufficient joint surface can be secured, and moreover, the tightening members are inserted into the boss portions at the front and rear of the steering shaft. Because they are fastened, the joint around the steering shaft is strong.

In addition, the rear end portions of the pair of left and right main frame portions are provided with a fastening member on the boss portion through a bridge portion having boss portions at least at two positions separated by a predetermined distance in the substantially longitudinal direction of the main frame portion. Since it is inserted and fastened in the direction, it is possible to effectively cope with lateral bending stress from the rear arm and the joint is strong.

[Embodiment] An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a side view of a motorcycle to which the invention is applied, and FIG.
The drawing is a sectional view taken along the line II-II of FIG. 1, and FIG. 3 is the drawing taken along the line III-III of FIG.
A sectional view, FIG. 4 is a sectional view taken along line IV-IV of FIG. 1, and FIG. 5 is an exploded perspective view of a divided frame.

In the drawing, reference numeral 1 is a vehicle body frame, and the vehicle body frame 1 is of a double cradle type, and is divided into two left and right steering shaft support portions 2 surrounding the steering shaft.
And a pair of left and right main frame portions 3 extending substantially linearly from the upper side of each split steering shaft support portion 2 to the upper side of the rear arm bracket portion 12, and further extending downward from the lower side of the split steering shaft support portion 2 and It has a pair of left and right sub-frame parts 4 that bend and extend to the lower side of the rear arm bracket part 12. Further, the rear arm bracket portion 12 has a rear arm support portion 39 and cross member attachment portions 26 and 27 above and below the rear arm support portion 39,
The rear arm bracket portion 12 includes upper and lower cross member attachment portions 26 and 27, and is configured by a portion between them.

This vehicle body frame 1 is formed by integrally casting a split steering shaft support portion 2, which is divided into left and right bodies, a loop-shaped main frame portion 3, a sub-frame portion 4, and a rear arm bracket portion 12, to form a split steering shaft. The shaft support portion 2 and the rear arm bracket portion 12 are made to face each other substantially in parallel,
Moreover, the main frame portion 3 and the sub frame portion 4 are made to face each other in a substantially triangular shape, and the volume of the split steering shaft support portion 2 is made larger than the volume of the rear arm bracket portion 12.

A steering shaft 7 is rotatably provided on the split steering shaft support 2, and a front fork 8 is rotatably supported on the steering shaft 7 via upper and lower brackets 9 and 10. A front wheel 11 is provided at the lower end of the front fork 8, and a handle (not shown) is provided at the upper end.

A seat rail 5 is provided on the rear side of the main frame portion 3, and the seat rail 5 is supported by a rear arm bracket portion 12 via a back stay 6. One end of a rear arm 13 is pivotally supported by the rear arm bracket portion 12, and a rear wheel 14 is provided on the rear arm 13 and is supported by the vehicle body frame 1 via a shock absorber (not shown).

The divided steering shaft support portion 2, the main frame portion 3, the sub frame portion 4, and the rear arm bracket portion 12 of the vehicle body frame 1 are configured by connecting divided frames 15 which are symmetrically divided into two. The split frame 15 is formed by casting a light metal material such as aluminum (including alloy) or magnesium (including alloy).

Ring press-fitting step portions 17 are formed on the upper and lower ends of the semi-cylindrical body 16 of the split steering shaft support 2, and boss portions 18 are formed on the front and rear sides of the semi-cylindrical body 16 at right angles to the steering axis direction. A bolt insertion hole 19 is formed in the boss portion 18 in a direction orthogonal to the body frame center plane M. The joint rib portion 20 of the semi-cylindrical body 16 is formed over substantially the entire length of the split steering shaft support portion 2 and is machined parallel to the center plane M of the vehicle body frame. The joining rib portions 20 directly abut each other to form the upper and lower rings 2
1, 22 are press-fitted into the ring press-fitting step portions 17 of the semi-cylindrical body 16, respectively, and the tightening bolts 23 are inserted into the bolt insertion holes 19 so that nuts
Is fixed by screwing.

Thus, the joining rib portion of the split steering shaft support portion 2
Since 20 is formed over substantially the entire length of the steering shaft 7, a sufficient joint surface can be secured, and since it is fastened with a tightening bolt 23 as a tightening member before and after the steering shaft 7, a joint around the head pipe is joined. Is strong.

The cross member mounting portions 26, 27 on the rear side of the split frame 15 are
Each of them is connected by a cross member 25 as a bridging portion, and the cross member mounting portions 26 and 27 serve as a connecting portion between the rear end portion of the main frame portion 3 and the rear end portion of the sub frame portion 4 and the rear arm bracket portion 12. There is. The cross member mounting portions 26 and 27 have member insertion holes 28 and
29 is formed, and member joining surfaces 30 and 31 are formed around the member insertion holes 28 and 29. The member joint surfaces 30 and 31 are machined in parallel with the body frame center plane M, and the member joint surfaces 30 and 31 have member insertion holes 28 and 31.
Bolt insertion holes 32 are provided at symmetrical positions with 29 in between, with a predetermined distance in the substantially longitudinal direction of the main frame.

For the cross member 25, a steel pipe material having a circular cross section is used, and both ends of the cross member 25 are similarly welded with steel boss portions 33, and the boss portions 33 allow member insertion holes 28, 29. An insertion portion 34 that is press-fitted in is formed. Bolt insertion holes 35 are bored in the longitudinal direction of the boss portion 33.

The cross member 25 is made orthogonal to the center plane M of the vehicle body frame, and the member insertion holes 28 and 29 of the divided frame 15 are inserted into the insertion portion 34 thereof until the member joint surfaces 30 and 31 abut against the boss portion 33. It is press-fitted and arranged, and is tightened and fixed by a tightening member such as a tightening bolt 36 and a nut 37. The connection between the pair of divided frames 15 and the cross member 25 is made by the cross member.
Rigidity is enhanced on the two surfaces of the insertion portion 34 and the boss portion 33 of 25 and the member insertion holes 28 and 29 of the divided frame 15 and the member joint surfaces 30 and 31. In addition, cross members
25 is connected to the rear end portion of the main frame portion 3 and the rear end portion of the sub-frame 4 by a connecting portion, so that the split frame 15 is also highly twisted.

Further, the rear end portions of the pair of left and right main frame portions 3 are fastened to the cross member 25 with fastening bolts 36 and nuts 37 as fastening members at at least two locations spaced apart by a predetermined distance in the substantially longitudinal direction of the main frame. Therefore, the lateral bending stress from the rear arm 13 can be effectively dealt with, and the joint is strong.

A pair of brackets 38 are welded to the cross member 25 so as to project to the front side, and an internal combustion engine (not shown) is fixed to the brackets 38, and the rear end of the internal combustion engine is supported by the cross member 25. It is like this.

A tightening bolt hole 39 for fixing the seat rail 5 is formed in the central portion of the main frame portion 3, and a rear arm support portion 40 into which a rear arm pivot 50 for pivotally supporting the rear arm 13 is inserted is formed in the rear arm bracket portion 12. Further, a fastening bolt hole 41 for fixing the back stay 6 is formed at the connecting portion between the main frame portion 3 and the rear arm bracket portion 12.
Are formed.

As the mold K forming the pair of divided frames 15, a rectangular parallelepiped having a cross-sectional shape as shown in FIG. 1 is used. Generally, a casting machine for setting a mold is designed to press the mold K at four corners, so that the mold K has a rectangular parallelepiped shape. This vehicle body frame 1 is formed by integrally casting a split steering shaft support portion 2, which is divided into left and right bodies, a loop-shaped main frame portion 3, a sub-frame portion 4, and a rear arm bracket portion 12, to form a split steering shaft. Since the shaft supporting portion 2 and the rear arm bracket portion 12 are opposed to each other substantially in parallel, and the main frame portion 3 and the sub frame portion 4 are opposed to each other in a substantially triangular shape, it is possible to effectively use the rectangular parallelepiped mold K to make a surplus. The body frame 1 is cast without any parts, and it becomes possible to form a body frame with a small number of parts without using a mold having a special shape.

Further, the vehicle body frame 1 has a split steering shaft support portion 2 which is divided into left and right bodies, a loop-shaped main frame portion 3, a sub frame portion 4 and a rear arm bracket portion 12 which are integrally formed by casting. It is possible to use the one having the same depth, suppress an increase in manufacturing cost, and easily cast and mold the lightweight and rigid body frame 1. Further, since the volume of the split steering shaft support portion 2 is larger than the volume of the rear arm bracket portion 12, the loop-shaped main frame portion 3 and the sub frame portion 4 are formed by melting the melt from the split steering shaft support portion 2 side. And rear arm bracket part 12
The hot water around is good and the whole is uniform, and the whole can be cooled uniformly.

The member insertion holes 28 and 29 are press-fitted into the insertion portions 34 of the cross member 25 assembled to the engine via the bracket 38 in the split frame 15, and the boss portions 33 are pressed against the member joint surfaces 30 and 31. Assemble and tighten with the tightening bolt 36 and nut 37.

On the other hand, the front side of the divided frame 15 is a joining rib portion of the semi-cylindrical body 16.
The upper and lower rings 21 and 22 are press-fitted into the ring press-fitting step portion 17 formed in the semi-cylindrical body 16 by abutting each other, and the front and rear sides of the semi-cylindrical body 16 are tightened by the tightening bolt 23 and the nut 24. Tighten and fix. In this way, the split steering shaft support portion 2 composed of the split frames 15 assembled together is formed.
The steering shaft 7 is attached to the main frame portion 3, and the seat rail 5 and the back stay 6 are attached to the main frame portion 3.

As described above, since the split steering shaft support portion 2, the main frame portion 3 and the sub-frame portion 4 are configured by the split frame 15 that is cast and formed of a light metal material, the weight is reduced and the connecting means of the split frame 15 is achieved. As described above, the welding method is not used, and the bolts and nuts are connected by a fastening member. That is, the divided frame 15 is formed on the two surfaces of the insertion portion 34 and the boss portion 33 of the cross member 25 and the member insertion hole 28 and the member joint surfaces 30 and 31 of the divided frame 15 via the cross member 25. Moreover, since the joint surface between the boss portion 33 and the divided frame 15 is enlarged, the connecting portion of the divided frame 15 is reinforced and the rigidity thereof is further improved.

And since it does not apply heat like welding when connecting,
Since the strength of the cast member is maintained as it is, the rigidity of the connecting portion is improved, and the distortion of the connecting portion is also reduced to improve the accuracy.

Further, since the divided frame 15 is assembled to the cross member 25 assembled to the internal combustion engine, the cross member 25
If the above is used in common, it is possible to combine a large and complicated internal combustion engine with an arbitrary type body frame 1. Further, the member joining surfaces 30, 31 to which the joining rib portion 20 on the front side of both the divided frames 15 and the boss portion 33 of the cross member 25 on the rear side are joined are parallel to each other with respect to the center plane M of the vehicle body frame. Further, since the member insertion holes 28, 29 and the bolt insertion hole 32 are formed so as to be orthogonal to each other, the work of cutting work is easy and the accuracy is further improved.

[Advantages of the Invention] As described above, according to the present invention, the left and right split steering shaft support portions that surround the steering shaft and the pair of left and right main frame portions that extend rearward of the vehicle body from the respective split steering shaft support portions are provided. Since the pair of left and right rear arm bracket portions extending downward from the rear of each main frame portion are integrally formed by casting of left and right light metal materials, the weight of the vehicle body frame and the number of parts can be reduced.

Further, the split steering shaft support portion of the vehicle body frame abuts front and rear joining rib portions surrounding the steering shaft, and inserts the fastening member in the vehicle width direction into boss portions provided on the front and rear joining rib portions of the steering shaft. Then, the joint ribs of the split steering shaft support are formed over almost the entire length of the split steering shaft support, so a sufficient joint surface can be secured, and the boss portions before and after the steering shaft are secured. Since the fastening member is inserted and fastened, the joint around the steering shaft is strong.

Further, at the rear end portions of the pair of left and right main frame portions, a fastening member is attached to the boss portion via a bridge portion having boss portions at least at two positions separated by a predetermined distance in the substantially longitudinal direction of the main frame portion. Since it is inserted and fastened in the direction, it is possible to effectively cope with lateral bending stress from the rear arm and the joint is strong.

As described above, the joint strength of the body frame, which is formed by casting the light metal material into the left and right halves, can be easily and reliably improved, particularly in the portion where the load is concentrated.

[Brief description of drawings]

FIG. 1 is a side view of a motorcycle to which the invention is applied, and FIG.
The drawing is a sectional view taken along the line II-II of FIG. 1, and FIG. 3 is the drawing taken along the line III-III of FIG.
A sectional view, FIG. 4 is a sectional view taken along line IV-IV of FIG. 1, and FIG. 5 is an exploded perspective view of a divided frame. In the figure, reference numeral 2 is a split steering shaft support portion, 3 is a main frame portion, 12 is a rear arm bracket portion, and 15 is a split frame.

Claims (1)

[Claims] 1. A split steering shaft support part that is divided into two parts on the left and right sides that surround a steering shaft, a pair of left and right main frame parts that extend rearward from the respective split steering shaft support parts, and each of the main frame parts. A pair of left and right rear arm brackets extending downward from the rear are integrally formed by casting of left and right light metal materials, and the front and rear joint ribs surrounding the steering shaft of the split steering shaft support are substantially the entire length of the split steering shaft support. The split steering shaft support portion abuts the front and rear joint rib portions, and the fastening member is inserted in the vehicle width direction into boss portions provided on the front and rear joint rib portions of the steering shaft. And the rear end portions of the pair of left and right main frame portions are separated by a predetermined distance in the substantially longitudinal direction of the main frame portion. At least two locations via a bridge portion having a boss portion, a body frame of the motorcycle, characterized in that fastened by inserting a fastening member in the vehicle width direction to the boss portions.