JP2003127953A - Body frame for motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motorcycle which can reduce the size and the weight of a body frame, and facilitates the trick cycling or the like. SOLUTION: A pair of right and left main frames 12 extending downwardly to the rear from a head pipe 11 are provided. Rear end parts of the main frames 12 are connected to a crank case cover 10. A stay 13 for supporting a seat 66 extending upward of a crank case 8 with a lower end part thereof supported by the crank case 8 and a front end part thereof supported by front end parts of the main frames 12 is provided. A motorcycle body frame 6 comprises the main frames 12, the crank case cover 10, and the stay 13 for supporting the seat 66.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorcycle body frame which can be reduced in size and weight.

[0002]

2. Description of the Related Art Conventionally, there is a so-called free-style bicycle as a motorcycle for riding a song. This freestyle bicycle has various ways of riding and enjoys the riding action, and shows the riding posture and running form to the audience as a performance. A motorcycle capable of performing such traveling has not been manufactured in the past.

[0003]

SUMMARY OF THE INVENTION The inventors of the present invention are trying to make it possible to easily perform the above-described bending on a motorcycle. However, in order to allow the conventional motorcycle to perform curved riding equivalent to that of the freestyle bicycle described above, it is necessary to further reduce the size and weight of the body frame.

In a conventional motorcycle body frame, a tank rail extending rearward from the head pipe above the engine, a down tube extending rearward and downward from the head pipe below the tank rail, and a rear end portion of the tank rail. Mostly, it is composed of a seat pillar tube and a rear arm bracket that connect the rear end of the down tube and the rear tube. The engine is supported by the tank rail of the vehicle body frame, the seat pillar tube / rear arm bracket, and the down tube via the bracket. For this reason, there is a limit to realizing the weight reduction while maintaining the necessary minimum strength, and it is not always possible to make the structure easy to bend.

The present invention has been made to solve the above problems, and an object of the present invention is to reduce the size and weight of a vehicle body frame and to realize a motorcycle that is easy to bend.

[0006]

In order to achieve this object, a vehicle body frame for a motorcycle according to the present invention is connected to a pair of left and right main frames extending rearward and downward from a head pipe and rear end portions of the main frames. A part of the crankcase and a seat support stay extending above the crankcase with the lower end supported by the crankcase and the front end supported by the front end of the main frame.

According to the present invention, the frame member extending rearward from the head pipe is only the main frame and the seat supporting stay, and the body frame is formed by utilizing a part of the crankcase. A relatively large and heavy frame member such as a tank rail and a seat pillar tube used in a motorcycle body frame is no longer necessary. Further, a member such as a bracket for mounting the engine on the vehicle body frame becomes unnecessary.

A motorcycle body frame according to a second aspect of the present invention is the motorcycle body frame according to the first aspect of the present invention, in which a part of the crankcase for connecting the main frame is a crankcase body. The crankcase cover is detachably attached to the side of the. According to the present invention, since the vehicle body frame is formed by using the crankcase covers that are formed relatively large to cover both side portions of the crankcase, the engine can be firmly mounted on the vehicle body frame. .

A motorcycle body frame according to a third aspect of the present invention is the motorcycle body frame according to the first aspect of the present invention, in which a part of the crankcase for connecting the main frame is a crankcase body. It is a bracket protruding from the front part of the. According to the present invention, the crankcase cover can be removed with the engine mounted on the vehicle body frame.

A motorcycle body frame according to a fourth aspect of the present invention is the motorcycle body frame according to any one of the first to third aspects of the invention, wherein the main frame is an engine cylinder. It is extended substantially parallel to the cylinder on the side of. According to the present invention, the cylinder of the engine is covered by the main frame from both sides.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a vehicle body frame for a motorcycle according to the present invention will be described in detail below with reference to FIGS. FIG. 1 is a side view of a bending motorcycle using a vehicle body frame according to the present invention, and FIG. 2 is a plan view of the same. FIG. 3 is a perspective view of the vehicle body frame, which is shown with the rear arm attached.

In these figures, the reference numeral 1 designates a motorcycle for riding a song according to this embodiment. This motorcycle 1 has a structure in which the front wheels 2 are steered by the steering wheel 3 and the rear wheels 4 are driven by the engine 5, which is the same as the conventional one, but the vehicle body frame 6 according to the present invention makes it easy to bend. Is configured as follows. The engine 5 is an air-cooled 4-cycle single-cylinder type engine, and is provided in a crankcase 8 with the cylinder 7 tilted so that its axis extends forward and upward. This crankcase 8
Is composed of a left and right split type crankcase body 9 to which the cylinder 7 is attached, and a crankcase cover 10 attached to both sides of the crankcase body 9.

The body frame 6 includes a head pipe 11
A pair of left and right main frames 12 extending rearward and downward from the head pipe 11, the crankcase cover 10 connected to the rear end of the main frame 12, and the crankcase body 9 supporting the lower end and the front end. Is supported by the front end of the main frame 12 and is constituted by a seat supporting stay 13 extending above the crankcase 8.

The head pipe 11 rotatably supports the front fork 14 and the steering handle 3. The front fork 14 is an inverted type, and the lower end bracket 1 of the inner cylinder 15 located on the lower side is used.
The front wheel 2 is rotatably supported by 6 and the front fender 17 is also supported. The front fender 17 is supported by the lower end bracket 16 via a fender stay 18 that extends vertically in front of the vehicle body from the inner cylinder 15. In this embodiment, a brake caliper 20 for a front brake 19 is attached to a fender stay 18 on the left side of the vehicle body.

The lower end bracket 16 of the inner cylinder 15
Is provided with a sub footrest 21 so that an occupant can put his / her foot on the axle portion of the front wheel 2 when riding a vehicle. The sub footrest 21 includes a mount 21a fixed to the lower end bracket 16 and the mount 21a.
And a cushion 21b fixed to the lower end bracket 16 so as to project laterally. The position to attach this sub footrest 21 is
It is set so as to be located on the same axis as the axle 2a of the front wheel 2.

The cushion 21b is made of rubber or synthetic resin so that the shoe placed on it will not slip easily and will be elastically deformed slightly in accordance with the sole of the shoe to be stable when placed. , In order to prevent the footrest position from being restricted when the body is tilted greatly with the foot rested, it is formed to have a taper whose outer diameter becomes gradually smaller toward the outside of the carbody. ing.

In this embodiment, in order to prevent the shoe from coming into contact with the brake disc 22 when the foot is placed on the sub footrest 21, the protective disc 23 that covers the brake disc 22 from the side is provided. It is attached to the lower end bracket 16. Further, when the foot is placed on the sub footrest 21 on the left side of the vehicle body, the ankle can be stabilized by pressing the ankle against the brake caliper 20.

The main frame 12 is divided into a left half portion 24 of the vehicle body and a right half portion 25 of the vehicle body, and the front end portion of the vehicle body is fixed to the head pipe 11 by fixing bolts 26 (see FIG. 1). In addition, the rear end of the vehicle body is fixed to the crankcase cover 10 by the fixing bolt 27. The left half half 24 and the right half half 25 of the vehicle body are formed by die-casting method using aluminum alloy as a material so as to have a vertically elongated cross section. It is formed so as to extend substantially parallel to.

The main frame 12 according to this embodiment
Is formed so that a front end portion connected to the head pipe 11 and a rear end portion connected to the crankcase cover 10 respectively extend from the upper end to the lower end without interruption, and between the front end portion and the rear end portion. The middle part is formed by the upper bar 12a and the lower bar 12b. Both of these bars 1
An opening 12c is formed between 2a and 12b. Cross members 28 and 29 extending in the vehicle width direction are formed on the upper bar 12a and the lower bar 12b, respectively. These cross members 28, 29 are formed integrally with the left half half 24 of the vehicle body of the main frame 12 and integrally formed with the right half half 25 of the vehicle body. It is configured by combining with each other in the central part. The main frame 12
Can be formed by a single frame member that is wide in the vertical direction, in addition to forming the middle portion by dividing it into an upper bar 12a and a lower bar 12b, and by forming it as in this embodiment, it becomes solid. Besides forming, it can also be formed by a pipe.

The main frame 12 is connected to the head pipe 11 by providing a connecting bracket 11a (see FIG. 1) on the rear portion of the head pipe 11 on the joining line between the main frame 12 and the left half 24 of the main frame 12. Half 2 on the right side of the vehicle
5 is performed by tightening these three members together with the two fixing bolts 26 while sandwiching the bracket 11a from both sides.

To connect the main frame 12 to the crankcase cover 10, a convex portion 31 is formed at the front end portion of the crankcase cover 10, and a concave portion 32 is formed at the rear end portion of the main frame 12 to be fitted into the convex portion 31. Is formed, and the convex portion 31 and the concave portion 32 are fitted to each other, and the two are fastened with the two fixing bolts 27. By adopting this connecting structure, the crankcase cover 10 can be accurately positioned on the main frame 12, and the load is transmitted between the main frame 12 and the crankcase cover 10 via the fitting surface. Thus, the load on the fixing bolt 27 can be reduced.

Further, a fuel tank 33 is accommodated in a space formed between the upper half of the main frame 12 and the left half 24 of the vehicle body and the right half 25 of the vehicle body. The cap that opens and closes the fuel filler port of the fuel tank 33 is indicated by reference numeral 33a in FIGS. In this embodiment, the fuel tank 33 is covered with a plastic tank cover 34. This tank cover 3
4 has a lower end supported by the crankcase body 9 of the engine 5 and an upper end supported by the main frame 12.

Furthermore, the left and right main frames 1
A muffler 35 is housed between the two. The muffler 35 is formed in a rectangular tube shape along the lower edges of the main frame 12 and the crankcase cover 10, and has a cylinder at the upstream end that is opened in front of the cylinder 7 so as to be directed forward and upward. The exhaust pipe 36 derived from 7 is connected. The downstream end of the muffler 35 extends along the lower surface of the crankcase body 9 to the rear end of the crankcase 8 and opens rearward at a substantially central portion in the left-right direction of the vehicle body. .

The crankcase cover 10 connected to the rear end of the main frame 12 is formed in such a shape as to cover both ends of the crankcase body 9 of the engine 5 from the lateral side over substantially the entire area, and the crankcase body 9 is provided with a plurality of crankcase covers 10. It is fixed by a fixing bolt 41. The crankcase cover 10 constitutes a part of the crankcase 8 according to the present invention. A rear arm 43 is supported on the rear end of the crankcase cover 10 via a pivot shaft 42 so as to be vertically swingable.

As is well known, the rear arm 43 rotatably supports the rear wheel 4 by an arm body 44 on the left side of the vehicle body and an arm body 45 on the right side of the vehicle body (see FIG. 3). It has a structure in which the arm bodies 44 and 45 are connected in front of the rear wheel 4 by a cross member 46 (see FIG. 3). Also, this rear arm 43
The front ends of the arm bodies 44 and 45 are connected to the pivot shaft 42.
Cushion stays 47a and 47b, which are supported by the crankcase cover 10 and extend upward from the both arm main bodies 44 and 45, are connected to the crankcase main body 9 of the engine 5 via a rear cushion unit 48. As shown in FIG. 1, the rear cushion unit 48 is arranged near the upper portion of the crankcase body 9 and is provided so as to be substantially parallel to the upper edge of the crankcase cover 10 in a side view. By arranging the rear cushion unit 48, which is a heavy object, in the vicinity of the crankcase body 9 as described above, the mass can be concentrated, and the operation becomes easy when riding a curve.

Rear wheel 4 by both arm bodies 44, 45
3 is provided with a rear end bracket indicated by reference numeral 49 in FIG. 3 on both arm main bodies 44 and 45.
This is done by fixing the axle 4a of the rear wheel 4 to the. The front fork 1 is attached to the rear end bracket 49.
The sub footrest 21 as well as the lower end bracket 16 of 4
Is provided. The sub footrest 21 has a structure similar to that provided on the front wheel 2 side, and the rear end bracket 4
The mount 21a fixed to the mount 9 and the cushion 21b fixed to the mount 21a are formed to have a circular cross section so as to project laterally from the rear end bracket 49.

The position where the rear wheel side sub footrest 21 is mounted is set so as to be located on the same axis as the axle 4a of the rear wheel 4. The cushion 21b is used for the front wheel 2
Like the sub footrest 21 on the side, it is formed of rubber or synthetic resin, and is formed so that the outer diameter becomes gradually smaller toward the outside of the vehicle body. In this embodiment, the protective disc 51 is fixed to the rear end bracket 49 so that the shoe does not come into contact with a rotating member in the vicinity when the foot is placed on the sub footrest 21 on the rear wheel 4 side and the vehicle runs. ing. On the left side of the vehicle body, the rotating member is a chain sprocket 52a around which a chain 52 for transmitting engine power is wound, and on the right side of the vehicle body, a brake disc 53 (see FIG. 2) of a rear brake.

In FIG. 1, the reference numeral 54 provided on the crankcase cover 10 on the left side of the vehicle body is a lid for closing the maintenance opening 55 formed in the crankcase cover 10. The lid 54 is detachably attached to the crankcase cover 10 with fixing bolts 56. In this embodiment, the lid 54 is formed in a circular shape in a side view, and a plastic protective cover 57 is attached to the outer peripheral portion. On the other hand, as shown in FIG. 3, the crankcase cover 10 on the right side of the vehicle body forms an opening 58 for maintenance of the transmission, and the opening 58 is formed by a lid 59 (see FIG. 2) having a structure similar to the lid 54. Is blocked. As described above, the maintenance opening 5
By providing the protective covers 57 made of plastic on the lids 54 and 59 that close the 5, 58, the elasticity of the protective covers 57 can prevent the crankcase 8 from being damaged when the vehicle body is tilted to the ground. . In FIG. 2, the reference numeral 60 provided in front of the lid 59 is an oil filter cap.

Although not shown, the crankcase body 9 is of a left and right split type composed of a left half portion of the vehicle body and a right half portion of the vehicle body. The crankcase body 9 supports the crankshaft at the front portion and the mission at the rear portion. I am wearing. The output shaft of this mission projects to the left side of the vehicle body, and a chain sprocket is fixed to the projecting end to connect the chain 52. Further, the crankcase main body 9 has the vertically extending portion 61 of the seat supporting stay 13 and the lower end portion of the tank cover 34 fixed to the upper portion by fixing bolts 62 and 63, respectively, and the main footrest 6 to the lower rear portion.
4 is provided.

The seat supporting stay 13 includes the vertically extending portion 61 extending rearward and upward from the crankcase main body 9, and the front-rear extending portion 65 extending from the upper end of the vertically extending portion 61 to the front of the vehicle body. Are integrally formed by a die-casting method using an aluminum alloy as a material, and a sheet 66 and an air cleaner 67 are provided at a connecting portion between the extending portions 61 and 65. The vertical extending portions 61 are formed so as to form a pair in the left-right direction, and the front-rear extending portions 65 are formed in the center portion in the left-right direction.
The front end of the front-rear extending portion 65 has the main frame 12
It is supported by the cross member 29 provided in the. In order to straddle the front end portion of the front-rear direction extending portion 65 from above,
The fuel tank 33 is formed in a saddle shape.

As shown in FIG. 2, the seat 66 is arranged at a distance from the fuel tank 33 to the rear of the vehicle body, and a tail lamp 68 is provided at the rear end of the seat 66 at the center in the left-right direction. . By arranging the seat 66 in this way, one extending portion 65 in the front-rear direction is usually provided at a place where a fuel tank for ensuring a predetermined capacity is arranged.
Since there is only one, there is no hindrance when tilting the posture to a large extent, and it is possible to facilitate riding a song. It is also possible to hold the extension portion 65 in the front-rear direction and use it so that the occupant supports the state. The air cleaner 67 includes the vertically extending portion 61 of the seat supporting stay 13.
The carburetor 68 is housed in a space surrounded by the front-rear direction extending portion 65 and is connected to a carburetor 68 via an intake duct 69. The carburetor 68 is connected to the rear surface of the cylinder 7 via an intake pipe (not shown).

The main footrest 64 provided on the lower rear side of the crankcase body 9 is formed of a metal into a cylindrical shape in this embodiment, and the outer peripheral surface thereof is knurled to prevent slipping. The outer diameter of the main footrest 64 is set to be substantially constant from the base end portion to the tip end portion. By forming the main footrest 64 with a circular cross section in this manner, the degree of freedom in the riding posture is increased, and the foot should be placed in a stable state even when the vehicle body is greatly tilted in the vertical direction such as a wheelie. You can A gearshift pedal 71 is arranged near the main footrest 64 on the left side of the vehicle body as shown in FIG. 1, and a brake pedal 72 for the rear brake is arranged near the main footrest 64 on the right side of the vehicle body as shown in FIG. Are installed.

As shown in FIG. 2, the main footrest 64 and the subfootrests 21 on the front wheel 2 side and the rear wheel 4 side have substantially the same left-right position between the left side of the vehicle body and the right side of the vehicle body. It is arranged as follows.
Therefore, the occupant can easily remember the position of the footrest. Further, the sub footrest 21 on the front wheel 2 side, the main footrest 64, and the sub footrest 21 on the rear wheel 4 side are arranged so that the heights thereof are substantially equal when the occupant is on the vehicle. For this reason, it is possible to easily transfer between these footrests when riding a song, and it is possible to reduce the change in posture when transferring.

In the motorcycle 1 constructed as described above, the foot is placed on the cylindrical main footrest 64 for running the wheelie, and the foot is placed on the sub footrest 21 provided on the axis of the front wheel 2 and the rear wheel 4. It is possible to ride a song while taking various riding postures. In particular, when both feet are placed on the sub footrest 21 on the rear wheel axle, the weight of the occupant is not added to the main frame 12 side (although a part of the weight is added to the steering handle 3), It is easy to shift from normal driving to wheelie driving.

The body frame 6 of the motorcycle 1 includes a pair of left and right main frames 12 extending rearward and downward from a head pipe 11, a crank case cover 10 connected to the rear end of the main frame 12, and a crank case body 9. Is used for the conventional vehicle body frame for a motorcycle because it is constituted by a seat supporting stay 13 that extends above the crankcase 8 with the lower end supported by the front end of the main frame 12 and the front end supported by the front end of the main frame 12. The relatively large and heavy frame members such as the tank rail and the seat pillar tube which have been used, and the brackets and the like for mounting the engine on the vehicle body frame are not required. For this reason, it is possible to reduce the size and weight of the vehicle body. Therefore, by using the vehicle body frame 6,
It is possible to manufacture the motorcycle 1 that is easy to bend.

The crankcase cover 1 is formed to be relatively large so as to cover both sides of the crankcase 8.
Since 0 is used to form the vehicle body frame 6, the engine 5 can be firmly mounted on the vehicle body frame 6. Further, since the main frame 12 is extended to the side of the cylinder 7 of the engine 5 substantially in parallel with the cylinder 7,
The cylinder 7 is laterally covered by the main frame 12, so that the engine 5 can be protected by the main frame 12 and at the same time, the occupant's leg can be prevented from accidentally coming into contact with the cylinder 7 when riding on a curve.

In the above-described embodiment, the crankcase cover 1 is attached to the rear end of the main frame 12 of the vehicle body frame 6.
Although 0 is connected, the crankcase main body 9 can be connected instead of the crankcase cover 10. In the case of adopting this configuration, brackets are provided so as to project from both front and rear ends of the crankcase main body 9, and the rear end of the main frame 12 is fastened to the bracket with fixing bolts. By adopting this configuration, the crankcase cover 10 can be removed while the engine 5 is mounted on the vehicle body frame 6, so that the vehicle body frame 6 is constructed using a part of the engine 5, The engine 5 can be easily maintained. Further, the vehicle body frame 6 according to the present invention is not limited to the motorcycle 1 for riding a motorcycle, and other motorcycles for which miniaturization and weight reduction are required, such as motorcycles for running on a public road or for racing. Can also be used for

[0038]

As described above, according to the present invention, the frame member extending rearward from the head pipe is only the main frame and the seat supporting stay, and the body frame is formed by utilizing a part of the crankcase. Therefore, relatively large and heavy frame members such as tank rails and seat pillar tubes used in the conventional motorcycle body frame become unnecessary, and members such as brackets for supporting the engine become unnecessary. Therefore, it is possible to form a compact and lightweight motorcycle body frame, and by using this body frame, it is possible to provide a motorcycle that can easily bend.

According to the second aspect of the present invention, since the vehicle body frame is formed by using the crankcase covers which are formed relatively large to cover both side portions of the crankcase, the engine is firmly supported by the vehicle body. Can be mounted on the frame. For this reason, it is possible to provide a motorcycle body frame that is small and lightweight and has high engine support rigidity.

According to the third aspect of the present invention, the crankcase cover can be removed while the engine is mounted on the vehicle body frame. Therefore, although the engine is constructed using a part of the engine, It is possible to provide a motorcycle body frame that is easy to maintain.

According to the fourth aspect of the present invention, the cylinder is covered from the side by the main frame. Therefore, by forming the bending motorcycle with this body frame, the cylinder can be protected by the main frame. The main frame can prevent occupant's legs from accidentally coming into contact with the cylinder when riding on a curve.

[Brief description of drawings]

FIG. 1 is a side view of a bending motorcycle using a vehicle body frame according to the present invention.

FIG. 2 is a plan view of a bending motorcycle using a vehicle body frame according to the present invention.

FIG. 3 is a perspective view of a body frame.

[Explanation of symbols]

5 ... Engine, 6 ... Body frame, 7 ... Cylinder, 8 ...
Crank case, 9 ... Crank case body, 10 ... Crank case cover, 11 ... Head pipe, 12 ... Main frame, 13 ... Seat support stay.

Claims (4)

[Claims] 1. A pair of left and right main frames extending rearward and downward from a head pipe, a part of a crank case connected to a rear end of the main frame, a lower end of the crank case supported by the crank case, and a front end of the crank case. A vehicle body frame for a motorcycle, which comprises a seat supporting stay that is supported by a front end portion of a main frame and extends above a crankcase. 2. The motorcycle body frame according to claim 1, wherein a part of a crankcase connecting the main frame is a crankcase cover detachably attached to a side portion of the crankcase body. flame. 3. The motorcycle body frame according to claim 1, wherein a part of the crankcase connecting the main frame is a bracket projecting from a front portion of the crankcase body. 4. The motorcycle body frame according to any one of claims 1 to 3, wherein the main frame extends laterally of the cylinder of the engine substantially parallel to the cylinder. flame.