JPH0777875B2 - Motorcycle frame - Google Patents

Description

TECHNICAL FIELD The present invention relates to a vehicle body frame of a motorcycle in which an internal combustion engine is supported by a hollow box-shaped frame made of light metal and a down tube.

[Prior Art] A body frame of a motorcycle has a box portion connected to a head pipe, a pair of left and right main frame portions branching from the box portion and extending rearward, and a rear supporting a rear arm for supporting a rear wheel. An internal combustion engine is supported by a hollow box-shaped frame made of a light metal composed of a frame part and a down tube having a front end connected to the box part of the box-shaped frame and a rear end connected to the rear frame part. There is something.

[Problems to be Solved by the Invention] This light metal box-shaped frame is adopted for the purpose of weight reduction, and it is desired to suspend the internal combustion engine compactly and firmly by the box-shaped frame and the down tube. ing.

Further, the load of the internal combustion engine, the load from the rear wheels, and the load from the front forks supporting the front wheels act on the box portion connected to the head pipe. As a result, in particular, a compressive load may be generated on the upper surface of the box portion and a tensile load may be generated on the lower surface thereof, so that the box portion is bent, and rigidity corresponding to these loads is required.

Therefore, it is conceivable to weld the down tube directly to the lower surface of the box part of the box-shaped frame to increase the rigidity of the box part.However, if the front end of the down tube is directly welded, the diameter of the down tube is small and the The area of the part is small and sufficient rigidity cannot be obtained.

Further, since the down tube is relatively long, the welding operation is difficult, and particularly in the case of light metal welding, since heat transfer is good, the strength of the material may be reduced when the welding heat is concentrated.

This invention has been made against the background of such circumstances,
A motorcycle that gives a predetermined rigidity to the box-shaped frame by using a mounting member that connects the down-tube to a cylinder-shaped frame and the down tube of the internal combustion engine, which are arranged in a forward-moving manner, and which is compactly and strongly suspended. The purpose is to provide a body frame of.

[Means for Solving the Problems] In order to solve the above problems, a vehicle body frame of a motorcycle according to the present invention is a vehicle of a box part in which a parallel multi-cylinder is tilted forward to mount an internal combustion engine and which is connected to a head pipe. A dimension in the width direction is extended to the engine width of the internal combustion engine, and a pair of left and right main frame portions that branch from both ends in the vehicle width direction of the box portion and extend rearward so as to surround both left and right sides of the cylinder, A hollow box-shaped frame made of light metal, which is composed of a rear frame part that is connected to the rear parts of a pair of main frame parts and pivotally supports a rear arm that supports the rear wheels, and a pair of left and right mounting parts near both ends of the box part. A member is provided, and a supporting member is connected between the both mounting members and the lower surface of the box portion, and further, the front end portion of the down tube is connected to each of the pair of left and right mounting members, and the rear portion is connected to the lower portion of the rear frame portion. , The above The down tube is arranged close to the front side of the internal combustion engine along the front wall of the internal combustion engine.

[Operation] In the present invention, the hollow box-shaped frame extends the dimension of the box portion connected to the head pipe in the vehicle width direction to the engine width of the internal combustion engine, and branches from both ends of the box portion in the vehicle width direction. And extends rearward to surround the parallel multi-cylinder of the internal combustion engine,
By extending the box portion to the engine width of the internal combustion engine, the amount of bending in plan view when the main frame portion and the down tube pass by the side of the internal combustion engine can be reduced, and the rigidity of the box frame and the down tube is improved.

Further, since a part of the cylinder in the side view of the internal combustion engine has entered between the main frame parts and is arranged closely along the front wall of the internal combustion engine, a side view when the down tube passes in front of the internal combustion engine The down tube has a high rigidity, and the down tube extends along the front side of the internal combustion engine and is compact.

Also, a pair of left and right mounting members are welded to the box portion of the box-shaped frame connected immediately after the head pipe, and the supporting member is connected to the mounting member and the lower surface of the box portion, and the front end portion of the down tube is connected to this mounting member. It is connected. Therefore, even if the load of the internal combustion engine or the load from the rear wheel side is applied to the box part and the impact load is applied from the front fork side, the compressive load is generated on the upper surface of the box part and the tensile load is generated on the lower surface, The rigidity of the lower surface of the box portion is improved by the member and the supporting member, so that the lower surface of the box portion is not bent particularly by a tensile load.

Since the mounting member for improving the rigidity of the box portion is welded to the box portion, the area of the welded portion becomes larger than that in the case where the down tube is directly welded, and there is no member that obstructs the welded portion. The welding operation is easy and stable welding is performed. Further, by using the mounting member and the supporting member, the box portion can obtain a predetermined rigidity without using a dedicated reinforcing member.

[Embodiment] An embodiment of a vehicle body frame of a motorcycle according to the present invention will be described below in detail with reference to the accompanying drawings.

In the figure, reference numeral 1 is a vehicle body frame of a motorcycle, and a head pipe 2 constituting the vehicle body frame 1 is rotatably supported by a front fork 3 via a steering shaft (not shown). A front wheel (not shown) is supported on the lower end of the front fork 3, and a handle 4 is attached to the upper part thereof.

A box-shaped frame 5 is connected to the head pipe 2. The box-shaped frame 5 is made of, for example, a light metal such as aluminum (including alloy) or magnesium (including alloy). In this embodiment, the box-shaped frame 5 is formed of an aluminum member in the shape of a hollow box, and is composed of a box portion 6, a main frame portion 7 and a rear frame portion 8.

The box portion 6 is connected to the head pipe 2 and extends to the engine width of the internal combustion engine 16 and is formed by welding five aluminum plate members in a box shape, and the head pipe 2 is welded to the front center portion. Further, as shown in FIG. 2, a partition wall 9 is provided in the front-rear direction on the inner wall of the central portion of the box part 6, and the front end portions of the main frame parts 7 are connected to the left and right sides via a partition wall 10. The end portion extends rearward and has a bifurcated shape from the box portion 6.

Further, as shown in FIG. 4, the mounting members 11 are welded to both sides of the lower surface 6a of the box portion 6 so as to project downward, and the both ends of the support plate 12 are welded between the mounting members 11. Has been done. The support plate 12 is welded to the lower surface 6a of the box portion 6 so that the longitudinal direction thereof is oriented in the vehicle width direction. The mounting member 11 and the support plate 12 which is a support member are both formed of an aluminum material, and these and the lower surface 6a of the box portion 6 are welded to each other with the same material, and the welding work is performed on these welded portions. Since it is on the front side, the work is easy.

A pair of left and right down tubes 1 in the recess 11a of the mounting member 11.
The concave portion 13a formed at the front end portion of 3 is engaged, and is tightened and fixed by a bolt 14 so as to be removable.

As shown in FIG. 5, a rear end portion of the down tube 13 is formed with a protrusion 13b in the axial direction, and the protrusion 13b is engaged with a recess 8a formed in the lower end portion of the rear frame portion 8. And they are tightened and fixed by bolts 15. The down tube 13 is arranged from the front side to the lower side of the internal combustion engine.

The main frame portion 7 is formed by welding a divided body formed by bending two aluminum plate materials in a U-shaped cross section at the mating faces, and the bent portion 7a of the main frame portion 7 has a sleeve 7b.
Is provided to improve rigidity. The rear end portion of the main frame portion 7 is welded to the rear frame portion 8 and branched from both end portions of the box portion 6 in the vehicle width direction and bent so as to surround the parallel multi-cylinder 17 of the internal combustion engine 16 from both sides. It extends backwards.

In this way, by extending the box portion 6 to the engine width of the internal combustion engine 16, it is possible to reduce the amount of bending in plan view when the main frame portion 7 and the down tube 13 pass through the side of the internal combustion engine, and thus the box-shaped frame 5 And the rigidity of the down tube 13 is improved.

A parallel multi-cylinder internal combustion engine 16 is mounted in a space formed by the head pipe 2, the box-shaped frame 5 and the down tube 13. In this embodiment, a parallel 4-cylinder 4-cycle internal combustion engine is adopted, and a parallel multi-cylinder 17 is used. It is mounted by leaning forward.

Each cylinder 17 is inclined forward from the upper front side of the crank case 18 along the down tube 13, and the crank case 18 extends rearward and extends toward the main frame portion 7 and the down tube 13.
It is attached to the rear part and the rear frame part 8. A part of the cylinder 17 in the side view of the internal combustion engine 16 is the main frame portion 7.
Since the down tube 13 is arranged close to the front wall of the internal combustion engine 16, the amount of bending in the side view when the down tube 13 passes in front of the internal combustion engine can be reduced, and the down tube 13 has high rigidity, and Down tube 13 is internal combustion engine 16
Compact along the front side of.

The sprocket 19 of the internal combustion engine 16 is connected to a drive gear 22 of a rear wheel 21 via a chain 20, and the rear wheel 21 is swingably supported by the rear frame portion 8 via a rear arm 23.

An exhaust pipe 24 is connected to the front side of each cylinder 17,
The reference numeral 24 extends below the internal combustion engine 16 and extends rearward.

On the other hand, an intake passage 25 is integrally formed on the upper side of each cylinder 17, and the intake passage 25 extends straight upward. A carburetor 26 is connected to the intake passage 25 via a connecting pipe 27, and an external air suction pipe 28 is connected to the carburetor 26.

A fuel tank 29 is mounted on the main frame portion 7 and a seat rail 28 above the internal combustion engine 11, and a seat 30 is mounted on the seat rail 28 behind the fuel tank 29.

The fuel pump is installed in the recess formed on the front side wall of the fuel tank 29.
31 is accommodated, and the suction side of this fuel pump 31 is the fuel pipe 32
It is connected to the bottom of the fuel tank 29 through. On the other hand, the protruding side of the fuel pump 31 communicates with the float chamber of the carburetor 26 via the fuel pipe 33, and the carburetor 26 mixes fuel and air and supplies the mixed fuel and air to the fuel chamber.

On top of the box portion 6 of the box-shaped frame 5, electrical components for ignition 34
The ignition electrical component 34 is composed of an ignition coil 35 and an ignition unit 36 containing, for example, an igniter. The ignition coil 36 is connected to an ignition plug 38 of each cylinder 17 via an intention code 37.

Next, the operation of this embodiment will be described.

The hollow box-shaped frame 5 extends the dimension of the box portion 6 connected to the head pipe 2 in the vehicle width direction to the engine width of the internal combustion engine 16, and branches from both ends of the box portion 6 in the vehicle width direction to generate internal combustion. It extends rearward so as to surround the parallel multi-cylinders of the engine 16, and by extending the box portion 6 to the engine width of the internal combustion engine 16, a plane when the main frame portion 7 and the down tube 13 pass laterally of the internal combustion engine. The amount of bending when viewed can be reduced, and the rigidity of the box-shaped frame 5 and the down tube 13 can be improved.

Further, since a part of the cylinder 17 in the side view of the internal combustion engine 16 enters between the main frame portions 7 and is arranged closely along the front wall of the internal combustion engine 16, the down tube 13 passes in front of the internal combustion engine. In this case, the amount of bending when viewed from the side can be reduced, the down tube 13 has high rigidity, and the down tube 13 extends along the front side of the internal combustion engine 16 and is compact.

In addition, the internal combustion engine 16 mounted on the box-shaped frame 5 applies a load to the box portion 6, and the head pipe 2 receives a force and a bending moment due to a front wheel load, and also an impact due to unevenness of the road surface during traveling through the front wheel suspension. Load, inertia force during braking, etc. are applied.

Although a compressive load is generated on the upper surface 6b of the box portion 6 of the box-shaped frame 5 and a tensile load is generated on the lower surface 6a thereof, a pair of left and right mounting members 11 are welded to the lower surface 6a of the box portion 6 to form a pair of left and right members. By connecting the mounting member 11 and the lower surface 6a of the box portion 6 with a support member, the rigidity is improved and the box portion 6 of the box frame 5 does not bend.

Therefore, the rigidity is increased by the mounting member 11 which is a seat for mounting the down tube 13 without providing a special reinforcing member such as forming the box portion 6 thick or providing a partition wall inside the box portion 6. . As described above, the rigidity of the box portion 6 can be increased without increasing the weight of the vehicle body frame, and the weight can be reduced.

Further, the welding of the mounting member 11 is welding of aluminum materials, and the aluminum welding has good heat transfer, so that the concentration of welding heat may reduce the strength of the material. By the way, in the welding work, since the mounting member 11 is welded to the lower surface 6a of the box portion 6, the welding area is wider than that in the case where the down tube is directly welded, and since the welded portion is on the front side, workability is good and stable. Welding can be expected.

Although the down tube 13 is attachable to and detachable from the mounting member 11 in the above embodiment, it may be connected to the mounting member 11 by welding.

[Advantages of the Invention] As described above, according to the present invention, the hollow box-shaped frame extends the dimension of the box portion connected to the head pipe in the vehicle width direction to the engine width of the internal combustion engine. By branching from both ends, it extends rearward so as to surround the parallel multi-cylinder of the internal combustion engine, and by extending the box portion to the engine width of the internal combustion engine,
The amount of bending in plan view when the main frame portion and the down tube pass by the side of the internal combustion engine can be reduced, and the rigidity of the box-shaped frame and the down tube is improved.

Further, since a part of the cylinder in the side view of the internal combustion engine has entered between the main frame parts and is arranged closely along the front wall of the internal combustion engine, a side view when the down tube passes in front of the internal combustion engine The down tube has a high rigidity, and the down tube extends along the front side of the internal combustion engine and is compact.

Also, a pair of left and right mounting members are welded to the box portion of the box-shaped frame connected immediately after the head pipe, and the supporting member is connected to the mounting member and the lower surface of the box portion, and the front end portion of the down tube is connected to this mounting member. Since they are connected, the load of the internal combustion engine and the load from the rear wheel side are applied to the box part, the impact load is applied from the front fork side, the compressive load is generated on the upper surface of the box part, and the tensile load is generated on the lower surface. However, the rigidity of the lower surface of the box portion is improved by the mounting member and the supporting member, and it is not particularly bent by a tensile load.

In addition, since the mounting member that improves the rigidity of the box part is welded to the box part and the area of the welded part becomes larger than when directly welding the down tube, there is no member that interferes with the welded part. Work is easy, stable welding is performed, and by using the mounting member and the supporting member,
The box portion can have a predetermined rigidity without using a dedicated reinforcing member.

[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 plan view of the main part, FIG. 3 is an enlarged side view of the main part, FIG. 4 is a IV-IV sectional view of FIG. 3, and FIG. 5 is a VV sectional view of FIG. 1 ... Body frame, 2 ... Head pipe 5 ... Box frame, 6 ... Box section 6a ... Bottom surface, 7 ... Main frame section 8 ... Rear frame section, 11 ... Mounting member 13 ... Down Tube 16 ... Internal combustion engine

Claims (1)

[Claims] Claim: What is claimed is: 1. A parallel multi-cylinder is tilted forward to mount an internal combustion engine,
The dimension of the box portion connected to the head pipe in the vehicle width direction is extended to the engine width of the internal combustion engine, and the left and right sides branch from both ends of the box portion in the vehicle width direction and extend rearward so as to surround the left and right sides of the cylinder. A hollow box-shaped frame made of light metal, which comprises a pair of main frame parts and a rear frame part that pivotally supports a rear arm that supports rear wheels connected to the rear parts of the left and right main frame parts; A pair of left and right mounting members are provided in the vicinity of both ends of the section, a supporting member is connected between the both mounting members and the lower surface of the box, and the front ends of the down tubes are connected to the pair of left and right mounting members, respectively, and the rear portion Is connected to a lower portion of the rear frame portion, and the down tube is arranged in proximity to the front side of the internal combustion engine along the front wall of the internal combustion engine.