JPH0581477B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a motorcycle body frame formed by casting.

[Prior Art] Some motorcycle body frames include a pair of left and right main frames connected to a head pipe by welding, and rear ends of the main frames connected by welding with a cross member. The head pipe, main frame, and cross member are connected by welding square or round pipe materials, but with recent advances in casting technology, the body frame of a motorcycle is constructed from cast members. Attempts have been made to facilitate mass production or to improve the shape accuracy of the vehicle body frame, as disclosed in, for example, Japanese Patent Laid-Open No. 77991/1983.

[Problems to be Solved by the Invention] By the way, when forming a car body frame with such a shape by casting, the mold is large due to this shape, and the shape does not allow good flow of the metal, so it is difficult to cast the entire car body frame as one piece. It's not realistic to do that.

For this reason, it is conceivable to divide the car body frame into left and right sides and integrally mold them by casting, but when connecting the car body frames divided into left and right sides, it is important to position them with particularly high precision and to increase the strength of the connection. This has become a major issue.

This invention was made in view of the above points, and provides a motorcycle body that is relatively easy to cast while retaining the advantages of casting, and that can connect divided main frames precisely and firmly. The purpose is to provide a frame.

[Means for Solving the Problems] In order to solve the above problems, the motorcycle body frame of the present invention has a pair of left and right main frames extending from the vicinity of the steering shaft to the vicinity of the rear arm pivot. The main frames of the left and right main frames are each integrally formed by casting separately, and the front ends of the left and right main frames are directly connected by touching the mating surfaces at the front and rear of the steering shaft, and the rear ends are separate parts at the top and bottom of the rear arm pivot. It is characterized in that the cross member and the mating surfaces of the flange portions formed on the cross member are brought into contact and connected.

[Function] In this invention, the pair of left and right main frames extending from the vicinity of the steering shaft to the vicinity of the rear arm pivot are formed by molds, and the molds are small and have good flow. The front ends of this pair of left and right main frames are directly connected by abutting the mating surfaces at the front and rear of the steering shaft, and the rear ends are separate cross members above and below the rear arm pivot, and the flange part formed on this cross member. Since the mating surfaces of the main frames are brought into contact with each other and connected, the pair of left and right main frames formed by casting can be reliably aligned and firmly connected.

[Example] Hereinafter, an example of the present invention will be described in detail based on the accompanying drawings.

In the figure, reference numeral 1 denotes a vehicle body frame, and this vehicle body frame 1 uses a double cradle frame. A main frame 2 and a subframe 3 constituting a vehicle body frame 1 form a loop shape in a side view via a head pipe 4 and a rear arm bracket 5. The seat rail 6 is attached to the main frame 2, and its central portion is supported by a back stay 7 extending from the rear arm bracket 5.

A steering shaft 8 is rotatably provided on the head pipe 4, and a front fork 9 is rotatably supported on the steering shaft 8 via upper and lower brackets 10,11. A front wheel 12 is provided at the lower end of the front fork 9, and a handle (not shown) is provided at the upper end.

A rear arm bracket 5 is connected to the rear side of the subframe 3, the front side of a rear arm 14 is swingably supported at a rear arm pivot 13 of this rear arm bracket 5, and a rear wheel 15 is provided on this rear arm 14. .

The head pipe 4, the main frame 2, and the rear arm bracket 5 are composed of a split frame 16 that is symmetrically divided into two parts. The split frame 16 is integrally formed by casting a light metal material such as aluminum (including alloys) or magnesium (including alloys).

The pair of split frames 16 each include a semi-cylindrical body 17 obtained by dividing the head pipe 4 into two, a main frame 2 that bends outward from the top of the semi-cylindrical body 17 and extends rearward, and a main frame 2 that extends backward from the top of the semi-cylindrical body 17.
The rear arm bracket 5 is connected to the rear end of the rear arm bracket 5. This split frame 16 is formed into a slightly wide shape so as to have a predetermined strength and rigidity as a whole, and especially the connection part 18a between the semi-cylindrical body 17 and the main frame 2, or the rear arm bracket 5.
The connecting portion 18b and the rear arm bracket 5 are formed wide to provide sufficient strength.

On the other hand, the subframe 3 is, for example, a non-cast member, and is formed of aluminum, carbon fiber, or the like, which has strength and extensibility. In this embodiment, a rectangular pipe material formed by drawing aluminum material is used, and has a narrow shape and optimal rigidity. This subframe 3 is an internal combustion engine 19
It is bent according to the outer shape of the lower part from the front side.

Rings 20 and 21 are press-fitted into the upper and lower ends of the semi-cylindrical bodies 17 of the pair of split frames 16, and the front and rear of the semi-cylindrical bodies 17 are brought into close contact with the front and rear mating surfaces of the steering shaft 8, They are directly connected by being tightened and fixed by tightening means such as a tightening bolt 22 and a nut 23.

An upper connecting part 24 and a lower connecting part 25 are formed on the front side of the main frame 2. This upper connecting part 2
4, as shown in FIG. 2, the mounting parts 27 at both ends of the front upper cross member 26 are brought into close contact with each other,
It is fixed by screwing the tightening bolt 28.

In addition, as shown in FIG. 3, the lower connecting portion 25 has
Both ends 29a of the lower front cross member 29 are fixed with tightening bolts 30. The mounting boss portion 31 of the subframe 3 is applied to the lower connecting portion 25 from the outside, and is fixed by screwing a nut 33 onto a tightening bolt 32. Mounting boss part 3
1 is welded to the front end of the subframe 3, and the positioning when the subframe 3 is installed is determined by a rib 25 formed on the side from the top of the lower connecting part 25 to the front side.
This is done by contacting a.

The rear side of the main frame 2 has a separate rear upper cross member 3 above and below the rear arm pivot 13.
4, the rear lower cross member 35, the rear upper cross member 34, and the rear lower cross member 3.
The mating surfaces of the flange portions 34b and 35b formed in the flange portions 34b and 35b are brought into close contact with each other, and are connected by tightening means such as tightening bolts 36 and 38.

That is, as shown in FIG. 2, the rear upper cross member 34 has both ends 34a connected to the main frame 2.
The flange portion 34b is fitted into the fitting hole 3a of the
is in contact with the side surface of the main frame 2 to bring the mating surface into close contact. Each of the flange portions 34b is tightened and fixed to the main frame 2 by two tightening bolts 36.

Further, as shown in FIGS. 2, 4, and 5, the rear lower cross member 35 has both ends 35a.
is fitted into the insertion hole 5a of the rear arm bracket 5, and its flange portion 35b abuts against the inner surface of the rear arm bracket 5, bringing the mating surfaces into close contact.
The flange portion 35b of the rear lower cross member 35, together with the mounting boss portion 37 of the rear arm bracket 5 and subframe 3, is attached to the tightening bolt 38 with the nut 3.
It is fixed by tightening 9. The mounting boss portion 37 is fixed to the rear end of the subframe 3 by welding, and the positioning when installing the subframe 3 is performed using the mounting boss portion 37.
The rib 5 formed on the rear frame bracket 5
This is done by touching b.

Incidentally, as shown in FIG. 5, the attachment boss portion 37 of the subframe 3 can be tightened together with the bracket 40 of the footrest or stand when assembled with the rear arm bracket 5.

A V-type internal combustion engine 19 is provided in a space surrounded by the main frame 2 and subframe 3.
The upper part of the engine case of this internal combustion engine 19 is supported by the bracket 41 of the rear upper cross member 34, the rear part is supported by the bracket 42 of the rear lower cross member 35, and the lower part is supported by the subframe 3.
It is supported by a bracket 43 provided at.

In this way, the rear end of the main frame 2, which has a wide left and right width, is brought into close contact with the mating surfaces of the flanges 34b and 35b of the separate cross members 34 and 35, and
The left and right front ends are in close contact with the mating surfaces before and after the steering shaft 8, so the left and right main frames 2
The positioning can be done accurately and the bonding strength is high. In addition, the front ends of the left and right main frames 2 are
The front and rear of the steering shaft 8 are directly connected by contacting the mating surfaces in close contact with each other, and the rear end is a separate cross member 3.
Since the mating surfaces of the flange portions 34b and 35b of 4 and 35 are brought into contact and connected in close contact, the left and right main frames 2 can be firmly connected. moreover,
Since there is no need to provide the molds of the left and right main frames 2 with protrusions for connection, the hot water flow is good and cavities are less likely to form, and the molds are simple.

Further, the connecting portion 18a between the head pipe 4 and the main frame 2, and the connecting portion 18b between the rear arm bracket 5 itself and the main frame 2 are formed to have a wide width to obtain strength and rigidity. In this way, the vehicle body frame 1 can easily obtain optimal strength and rigidity simply by freely selecting its shape, such as by forming the frame into a wide frame.

In addition, the subframe 3 needs to be narrow in order to secure the bank angle, but since the frame other than the subframe 3 can be formed thicker than the subframe 3, the flow of metal during casting is In addition to improving the quality of the product, the mold is smaller and simpler because the subframe 3 is not integrally molded.

On the other hand, since the sub-frame 3 is formed from a non-cast member having strength and malleability, it can be made narrower than when integrally formed by casting, and it is easy to secure the bank angle. Furthermore, it is possible to sufficiently cope with shocks from the road surface and vibrations caused by the drive of the internal combustion engine 19.

In order to mount the internal combustion engine 19 on this vehicle body frame, first attach one of the left and right sides of the subframe 3 to the front mounting boss part 31 of the subframe 3 to the lower connecting part 25 of the main frame 2, and connect the rear mounting boss part 31 to the lower connecting part 25 of the main frame 2. Part 37
Place it on the mounting part of rear arm bracket 5,
Tighten and secure with tightening bolts 32, 38 and nuts 33, 39. Then, the internal combustion engine 19 is connected to the rear upper and lower cross members 3 of the main frame 2.
It is supported by brackets 41 and 42 of Nos. 4 and 35, and also supported by a bracket 43 of subframe 3 provided on the frame.

In this state, similarly attach the front mounting boss part 31 of the remaining subframe 3 to the lower connecting part 25 of the main frame 2, and the rear mounting boss part 37 to the mounting part of the rear arm bracket 5, and tighten them. The internal combustion engine 19 is supported on the vehicle body frame 1 by tightening and fixing with bolts 32, 38 and nuts 33, 39.
The subframe 3 is removable to support the internal combustion engine 19, and after the internal combustion engine 19 is supported on the split frame 16, it is assembled to support the internal combustion engine 19, so that assembly is easy.

Furthermore, main frame 2 of frame 1 of the vehicle body
The space for assembling the internal combustion engine 19 between the frame 1 and the subframe 3 can be reduced, a unified view can be obtained between the vehicle body frame 1 and the internal combustion engine 19, the appearance is good, and the bank angle can be large, making the vehicle body compact. .

[Effects of the Invention] As described above, the present invention has a pair of left and right main frames extending from the vicinity of the steering shaft to the vicinity of the rear arm pivot, and the pair of left and right main frames are separately cast and integrally formed. The front ends of the left and right main frames are directly connected by touching the mating surfaces in front and behind the steering shaft.
The rear end is connected to a separate cross member above and below the rear arm pivot by abutting the mating surfaces of the flanges formed on this cross member, so it is necessary to form a protrusion to connect it to the main frame. The result is a car body frame that is easy to mold, has good hot water flow, is hard to form cavities, has improved shape accuracy, is strong, and is easy to mold, making it suitable for mass production.

In addition, the front ends of the left and right main frames are in contact with the mating surfaces at the front and rear of the steering shaft, and the rear ends are in contact with the mating surfaces of the flanges of separate cross members. The positioning of the main frames can be performed accurately, and the connection strength is increased, making it possible to firmly connect the left and right main frames.

[Brief explanation of drawings]

Fig. 1 is a side view of a motorcycle to which the present invention is applied, Fig. 2 is a partially cutaway plan view of the body frame, Fig. 3 is a sectional view taken from Fig. 1, and Fig. 4 is a cross-sectional view of Fig. 1. - sectional view, FIG. 5 is a - sectional view of FIG. 1. In the figure, 1 is the body frame, 2 is the main frame, 3 is the subframe, 4 is the head pipe, 5 is the rear arm bracket, 16 is the split frame, 1
9 is the internal combustion engine, 26 is the front upper cross member, 2
9 is a front lower cross member, 34 is a rear upper cross member, and 35 is a rear lower cross member.

Claims (1)

[Claims] 1. It has a pair of left and right main frames that extend from near the steering shaft to near the rear arm pivot, and each of the left and right main frames is separately cast and integrally molded, and the front ends of the left and right main frames are connected to the steering shaft. The front and rear parts are directly connected by touching the mating surfaces, and the rear end is connected by touching the mating surfaces of a separate cross member and the flange formed on this cross member above and below the rear arm pivot. Characteristic motorcycle body frame.