JP2757006B2 - Motorcycle - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motorcycle having improved running stability and maneuverability by reducing the center of gravity of a vehicle body and shortening a wheel base.

(Prior art)

The running stability of the motorcycle can be improved by lowering the center of gravity of the vehicle. In order to lower the center of gravity of such a vehicle body, an engine of a motorcycle is generally mounted with a cylinder portion inclined forward. (Japanese Patent Laid-Open No. 58-
However, since a space for installing ancillary equipment such as a carburetor is also required on the upper side of the engine, simply leaning the cylinder forward has a limitation in lowering the center of gravity of the vehicle body. In addition, when the cylinder portion is tilted forward, the length of the engine in the front-rear direction is lengthened and the wheelbase is lengthened, which also causes a reduction in steering stability.

[Problems to be solved by the invention]

An object of the present invention is to provide a motorcycle in which the wheelbase is reduced as much as possible together with the lowering of the center of gravity of the vehicle body so that running stability and steering stability are simultaneously improved.

[Means for solving the problem]

In order to achieve the above object, the present invention has a structure in which a body frame has a vertically long frame member extending obliquely downward and rearward from a head pipe in a substantially straight line in a side view, and a crankshaft is provided on a cylinder portion projecting forward below the frame member. In a motorcycle equipped with a water-cooled engine having a transmission case portion connected through a portion, the cylinder portion and the transmission are formed in a U-shape that is convex upward from the crankshaft portion in a side view. While bending the case portion, the axis of the cylinder portion is inclined downward below a line connecting the crankshaft and the axle of the front wheel, so that the upper surface of the transmission case portion is along the lower surface on the rear side of the frame member. And an engine suspension portion is provided above the crankshaft portion,
A space is formed between a front side lower surface of the frame member and an upper surface of the cylinder portion so as to expand forward from the engine suspension portion, and two radiators are separated from each other at a front end of the space portion. In addition, a carburetor is disposed between the radiator and the engine suspension so as to face a space between the radiators.

〔Example〕

1 to 7 show a motorcycle according to an embodiment of the present invention, wherein 1 is a body frame, 2 is a water-cooled engine, 3 is a front wheel, and 4 is a rear wheel. The main part of the body frame 1 is configured such that a tank frame (frame member) 7 and a down tube 8 connect a head pipe 5 and a rear arm bracket 6 arranged in front and rear.

In this embodiment, a pair of left and right down tubes 8 are provided as shown in FIGS. 1 and 3, and an intermediate portion is bent downward in a side view as viewed in side view. The rear end side is welded to a pair of rear arm brackets 6 provided on the left and right, respectively. Further, the tank frame 7 is formed so as to be wide and substantially linear when viewed from the side, and so as to straddle a pair of left and right down tubes 8 and 8 when viewed in a plan view. And a tank space for storing fuel therein is formed. The tank frame 7 having such a shape has a front end connected to the head pipe 5 and a rear end connected to the rear arm bracket 6 by bolts. They are connected by bolts (see FIG. 6). As described above, the body frame 1 is very high because the bent two sides of the down tube 8 and the vertically long tank frame 7 extending linearly obliquely downward and backward from the head pipe 5 form a triangle in a side view. It will exhibit rigidity.

The case 2 is provided in the space above the tank frame 7 where the fuel tank is provided in the case of the conventional vehicle. In the case 24, for example, an electric component or a helmet can be stored.

A pair of front forks 9, 9 are supported on the head pipe 5 of the single frame 1 so as to be rotatable left and right about the axis of the head pipe 5, and a front wheel 3 is supported at the lower end thereof. A footrest 25 is fixed to the rear arm bracket 6. A rear arm 10 comprising a pair of left and right arm members 10a and 10b is pivotally supported on the rear arm bracket 6 by bolts 16 so as to be able to swing up and down (see FIG. 4). The rear wheel 4 is supported at the rear end of the arm 10. Also, the rear part of the arm 10 has a link mechanism
It is elastically supported by one shock absorber 12 via 11.

Further, of the pair of arm members 10a and 10b, the exhaust pipe 1
The arm member 10a located on the side where 3 is disposed has a shape in which an intermediate portion is curved upward in a chevron so as not to interfere with the exhaust pipe 13. That is, when the exhaust pipe 13 is bent, the bending resistance increases the exhaust resistance. Therefore, the exhaust resistance of the exhaust pipe 13 is reduced by bending the arm member 10a.

As shown in FIG. 3, the shock absorber 12 is configured such that the curved arm member is positioned with respect to a center line CL in the width direction of the vehicle body (a line connecting the center in the width direction of the front wheel 3 and the center in the width direction of the rear wheel 4). It is arranged eccentrically by a distance e on the opposite side to 10a. Further, the link mechanism 11 also has a curved arm member 10a similarly to the shock absorber 12.
And is eccentrically arranged by a distance e on the opposite side to the above, and is supported by the rear arm bracket 6 and the rear arm 10. As described above, when one of the pair of arm members 10a and 10b is extremely curved compared to the other, the curved arm member 10
The rigidity of a is smaller than that of the other arm 10b. In order to equalize such a difference in rigidity, a method of increasing the thickness of the curved arm member 10a is considered. However, if the buffer 12 is eccentric as described above, the curved arm member 10a Can be reduced, and the arm member 10a does not need to be thickened. As a result, the weights of the left and right arm members 10a, 10b can be balanced. This is also advantageous for improving the steering stability.

The engine 2 in this embodiment is a one-cylinder two-cycle engine. The engine 2 disposed below the tank frame 7 includes a cylinder portion 2c and a crankshaft portion 2f that project forward.
The transmission case 2m is connected to the cylinder 2c and the transmission case 2m is bent in an upwardly convex shape with the crankshaft 2f as a boundary in a side view. ing. The engine 2 has a crankshaft 14
And an engine suspension unit 30 provided above the center of gravity is suspended from the down tube 8 by bolts 15. The rear end of the engine is fixed to the rear arm bracket 6 by the pivot bolt 16 of the rear arm 10 (see FIG. 4).

With the engine 2 suspended in this manner, the cylinder portion 2c is inclined downward, and its axis EL corresponds to the crankshaft.
It is arranged below the line segment L connecting the axle 3c of the front wheel 3 to the axle 3c. The position of the crankshaft 14 is
The position is higher by a distance h than the 16 horizontal positions. The top of the transmission case 2m is the tank frame 7
Are arranged close to each other along the lower surface on the rear side.

A large space portion 31 expanding forward from the engine suspension portion 30 is formed between the lower surface on the front side of the tank frame 7 and the upper surface of the cylinder portion 2c. Two left and right radiators 18 and 18 for cooling the engine are arranged at a front end of the space 31 so as to be separated from each other, so that the air can smoothly pass through the separated space 19. The vaporizer 17 is located in this space 19 in plan view.
Radiators 18, 18 and engine suspension 30
And is covered with a case 20.
The case 20 is provided with a wind guide hole 21 extending rearward from the front surface, and being bent at a substantially right angle at the rear end to pass into the case. The case 20 prevents the supply air from being heated by the radiator 18 while preventing the dynamic pressure of the air supplied to the vaporizer 17 by the shape of the air guide hole 21.
The performance of the vaporizer 17 is stabilized.

A cowling 22 is provided on the outside of the vehicle body so as to cover the front side and both sides of the front part. A wind guide plate 23 is provided on the lower surface of the front end of the cowling 22, and the wind guide plate 23 enters from the front. The air is smoothly led to the air guide hole 21 of the case 20.

As described above, in the present invention, the axis of the cylinder portion 2c is
A large space portion 31 is formed which is inclined below the line segment L connecting the axle 3c of the front wheel 3 to the cylinder portion 2c and expands above the cylinder portion 2c.
Since the vaporizer 17 and the radiator 18 are arranged in the space 31, the tank frame 7 can be arranged as low as possible. Therefore, the center of gravity of the vehicle is reduced as a whole, and the running stability is improved.

The longitudinally extending tank frame 7 extends from the head pipe 5 obliquely downward and substantially linearly in a side view on the upper side of the transmission case 2m of the engine 2 bent in a U-shape with the crankshaft 2f projecting upward. An engine suspension unit 30 provided near the rear lower surface and provided above the crankshaft 2f.
A space portion 31 expanding forward from is formed, two radiators 18, 18 are arranged at the front end of the space portion 31, and the carburetor 17 is provided between the radiators 18, 18 and the engine suspension portion 30. 2m transmission case and tank frame 7
Both the small space formed therebetween and the space portion 31 expanding forward from the engine suspension portion 30 do not overlap vertically, and the expanding space portion 31 includes the radiators 18 and 18 and the carburetor 1.
7 can be stored compactly so that no unnecessary space is created between the tank frame 7 and the engine 2.
Therefore, the engine storage space below the tank frame 7 can be reduced in size, and the tank frame 7 can be further lowered to lower the vehicle height. As a result, the center of gravity of the vehicle body is lowered, so that running stability can be further improved.

The engine 2 is connected to the cylinder 2c and the transmission case 2m.
Since the front and rear parts of the engine 2 are bent so as to face downward so as to face downward, the front-rear length of the engine 2 is shortened, and the eastern part of the cylinder part 2c can be located at the rear lower side of the front wheel 3.
The wheelbase can be shortened.

Further, since the vaporizer 17 is exposed to the space 19 between the left and right radiators 18 and 18 separated from each other, even if the vaporizer 17 is provided close to the rear side of the radiator, the vaporizer 17 is heated by the cooling air heated by the radiator. Therefore, the performance of the vaporizer can be stably maintained.

Further, by suspending the engine 2 above the center of gravity, it is possible to improve the balance in strength against vibration during traveling.

 FIG. 8 shows another embodiment of the present invention.

In the first embodiment, the vaporizer is used for road racing.
Although an air purifier is not connected to 17, an air purifier 26 is connected to the vaporizer 17 in this embodiment. Moreover, the air purifier 26 is formed integrally with the front part of the tank frame 7.

FIG. 9 shows still another embodiment of the present invention.

In this embodiment, an air purifier 26 is connected to a vaporizer 17 as in the second embodiment (the embodiment in FIG. 8). However, the air purifier 26 of this embodiment is different from the second embodiment in that it is not formed integrally with the tank frame 7 but is formed separately.

FIG. 10 shows still another embodiment of the present invention.

In this embodiment, the vehicle body frame 1 is
The structure is such that the down tube 8 as provided in the third embodiment is not provided. Therefore, the engine 2 is suspended not on the down tube 8 but on the tank frame 7.

The engine mounted in the present invention is a single cylinder,
The engine is not limited to the cycle engine, and may be a parallel multi-cylinder, four-cycle engine.

〔The invention's effect〕

As described above, the motorcycle of the present invention has a configuration in which the vehicle body frame has a vertically long frame member extending substantially linearly obliquely downward and rearward from the head pipe in a side view, and a cylinder portion protruding forward below the frame member. In a motorcycle equipped with a water-cooled engine formed by connecting a transmission case portion via a crankshaft portion, the cylinder portion is formed in a U-shape which is convex upward from the crankshaft portion in a side view. And the transmission case part are bent, and the axis of the cylinder part is inclined downward from a line connecting the crankshaft and the axle of the front wheels, so that the upper surface of the transmission case part is on the rear side of the frame member. Proximity along the lower surface, and provide an engine suspension portion above the crankshaft portion, between the lower surface on the front side of the frame member and the upper surface of the cylinder portion A space that expands forward from the engine suspension portion is formed, and two radiators on the left and right sides are arranged at the front end of the space portion, and a carburetor is provided between the radiator and the engine suspension portion. It is arranged facing the separated space.

In this way, the axis of the cylinder is inclined below the line connecting the crankshaft and the axle of the front wheel to form a large space that expands above the cylinder, and a carburetor and a radiator are provided in the space. Is disposed, the frame member can be disposed as low as possible, thereby improving the lowering of the center of gravity of the vehicle body and improving the running stability.

In addition, the upper surface of the transmission case portion of the engine, which is bent in a U-shape to be convex upward with the crankshaft as a boundary, extends rearward from the head pipe in a substantially straight line obliquely downward and in a substantially straight line when viewed from the side. A space is formed along the lower surface so as to expand forward from an engine suspension provided above the crankshaft. Two radiators, left and right, are arranged at the front end of the space, and the radiator and the engine are arranged. Since the carburetor is arranged between the suspension and the engine, the small space formed between the transmission case and the frame member and the space that expands forward from the engine suspension are not overlapped vertically. In addition, since the radiator and the carburetor can be compactly stored in the expanding space, it is possible to avoid generating an unnecessary air gap between the frame member and the engine, and Can reduce the square of the engine housing space, thereby, since the frame member can be further reduced the vehicle height is lowered downward, it is possible to lower the center of gravity of the vehicle body, further enhance the running stability.

In addition, in order to bend the engine in a cross shape in a side view so that the cylinder portion and the transmission case portion face downward,
Since the front-rear length of the engine is shortened and the head of the cylinder portion can be positioned behind and below the front wheels, the wheelbase can be shortened and steering stability can be improved.

Furthermore, since the vaporizer is exposed to the space between the left and right radiators separated from each other, even if the vaporizer is provided close to the rear side of the radiator, the vaporizer is not heated by the cooling air passing through the radiator. Vessel performance can be stabilized.

[Brief description of the drawings]

FIG. 1 is a side view of a motorcycle according to an embodiment of the present invention,
2 is a front view showing only the essential parts, FIG. 3 is a plan view showing only the essential parts, FIG. 4 is a cross-sectional view of the rear arm pivot, and FIG. 5 is a cross-sectional view taken along the line AA of FIG. FIG. 6 is a sectional view taken along line BB of FIG. 1, and FIG. 7 is a sectional view taken along line CC of FIG. 8th
FIGS. 10 to 10 are side views of a motorcycle showing another embodiment of the present invention. 1 ... body frame, 2 ... engine, 2c ... cylinder section,
2f …… Crank shaft part, 2m …… Mission case part, 3…
... front wheel, 4 ... rear wheel, 5 ... head pipe, 6 ... rear arm bracket, 7 ... tank frame (frame member), 8 ... down tube, 9 ... front fork, 10 ...
… Rear arm, 17… vaporizer, 18… radiator, 19…
Space, 30 ... Engine suspension, 31 ... Space.

Claims (1)

(57) [Claims] 1. A vehicle body frame comprising a vertically elongated frame member extending substantially linearly obliquely downward and rearward from a head pipe in a side view, and a cylinder portion protruding forward below the frame member through a crankshaft portion. In a motorcycle equipped with a water-cooled engine connected to a transmission case portion, the cylinder portion and the transmission case portion are formed in a U-shape that is convex upward with respect to the crankshaft portion in side view of the engine. While bending, the axis of the cylinder portion is inclined downward below a line segment connecting the crankshaft and the axle of the front wheel, and the upper surface of the transmission case portion is brought close to and along the rear lower surface of the frame member, And an engine suspension portion provided above the crankshaft portion, and expands forward from the engine suspension portion between a lower surface on the front side of the frame member and an upper surface of the cylinder portion. A space part is formed, and two radiators on the left and right sides are spaced apart from each other at the front end of the space part, and a carburetor faces the space between the radiators between the radiator and the engine suspension part. Motorcycle placed.