JP2657665B2 - Body structure of motorcycle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vehicle body structure of a motorcycle including a fuel tank and an exhaust pipe.

(Prior Art) There is a vehicle body of a motorcycle configured as follows. That is, an inverted U-shaped fuel tank is provided so as to straddle the vehicle body frame. On the other hand, an exhaust pipe extends rearward from the engine. The exhaust pipe has an expansion chamber for utilizing exhaust pulsation in the middle part before and after the exhaust pipe, and the expansion chamber is located below a lower end of one side of the fuel tank.

In the above case, in order to prevent the fuel tank and the expansion chamber from contacting each other, the lower end of one side of the fuel tank and the upper surface of the expansion chamber are separated to some extent vertically in a side view, that is, A gap is provided between the two in the vertical direction.

(Problems to be Solved by the Invention) When the above-described gap is provided, when the fuel tank and the expansion chamber are viewed from the side, a sense of unity in appearance is lost between these two parts. This is undesirable because it causes the appearance of the vehicle body to deteriorate.

In addition, motorcycles are required to have mass concentration and a low center of gravity in order to improve stability, but it is preferable to provide gaps in the vertical direction as described above in order to satisfy the above requirements. For this reason, the conventional configuration has some points to be improved.

(Object of the Invention) The present invention has been made in view of the above-described circumstances, and improves the appearance of a vehicle body by creating a sense of unity in appearance between a fuel tank and an expansion chamber. ,
The aim is also to improve maneuverability by concentrating trout.

(Structure of the Invention) The feature of the present invention for achieving the above object is to provide an inverted U-shaped fuel tank in front view so as to straddle the body frame, face the fuel tank up and down,
The lower plate is formed by joining its outer edges to each other. On the other hand, the front and rear halfway of the exhaust pipe extending rearward from the engine is positioned below the lower end of one side of the fuel tank, and the front and rear halfway is connected to the vehicle. In a motorcycle formed by joining outer edges of left and right half cylinders facing each other in the width direction, a joint between outer edges of upper and lower plates at a lower end of one side of the fuel tank and an exhaust gas The point is that the joints between the outer edges of the left and right half-cylinders on the upper surface of the front and rear halfway portions of the pipe are overlapped in the vehicle width direction.

(Operation) The operation of the above configuration is as follows.

A joint 62 between the outer edges of the upper plate 45 and the lower plate 46 at the lower right end (lower end of one side) 57 of the fuel tank 27 and the exhaust pipe 25
The joining portion 63 of the outer edges of the left half cylinder 59 and the right half cylinder 60 on the upper surface of the expansion chamber (halfway section) 54 overlaps in the vehicle width direction. Therefore, when the fuel tank 27 and the expansion chamber (halfway portion) 54 are viewed from the side, there is no gap between them.

Further, as described above, the fuel tank 27 can be made to approach the expansion chamber (halfway between the front and rear portions) 54 by an amount corresponding to the overlapping of the two joint portions 62 and 63. For this reason, the concentration of the mass and the lowering of the center of gravity can be achieved.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

In FIG. 2, 1 is a motorcycle, 2 is a body frame thereof, and the body frame 2 has a semi-double cradle shape. That is, the vehicle body frame 2 has a head pipe 3 at a front portion thereof, a main frame 4 extends from the upper part of the head pipe 3 toward a rear lower part, and a pair of right and left seats is provided from a rear end of the main frame 4. A pillar tube 6 extends downward.

On the other hand, a down tube 7 is provided which extends rearward and downward from a lower portion of the head pipe 3 and has a rear end connected to a lower end of the seat pillar tube 6. The down tube 7 includes a front tube 8 extending rearward and downward from a lower portion of the head pipe 3, and a pair of left and right rear tubes that extend downward from the lower end of the front tube 8 and then bend rearward. It is composed of 9,9.

Further, left and right seat rails 11 extend rearward from the rear end of the main frame 4, and the rear portions of the seat rails 11 are supported by the back stays 12 below the seat pillar tubes 6.

A front fork 13 is supported on the head pipe 3 so as to be steerable. The front fork 13 supports a front wheel 14 at a lower end thereof, and supports a handle 15 at an upper end thereof.

On the other hand, a rear arm 17 is pivotally supported on the lower part of the seat pillar tube 6 so as to be vertically swingable, and a rear wheel 18 is supported on a swing end of the rear arm 17. 19 is a shock absorber.

Reference numeral 21 denotes a three-cycle engine. The engine 21 is fastened to the body frame 2. The engine 21 has an intake hole on the rear surface side, and a carburetor 22 is attached to the intake hole. On the other hand, the engine 21 has an exhaust hole on the front side thereof, one end of an exhaust pipe 25 is connected to the exhaust hole, the other end of the exhaust pipe 25 extends rearward, and a silencer 26 is provided at the rear end. Installed.

A fuel tank 27 for supplying fuel to the carburetor 22 is provided. The fuel tank 27 has an inverted U shape when viewed from the front, and is supported by the body frame 2 so as to straddle the main frame 4. A seat 28 is provided behind the fuel tank 27, and the seat 28 is supported by the seat rail 11. 29 is a rider and 30 is a footrest.

The engine 21 is provided with a drive sheave 32, while the rear wheel 18 is provided with a driven sheave 33, and a transmission chain 34 is wound around the both sheaves 32,33. The above engine
21 operates by sucking fuel from a fuel tank 27 together with outside air through a carburetor 22. If the power of the engine 21 is transmitted to the rear wheels 18 via the transmission chain 34 and the like, the motorcycle 1 can run.

A radiator 36 is provided on a front surface of the down tube 7. The radiator 36 cools the cooling water for cooling the engine 21 by traveling wind. Further, a radiator cover 37 is provided to cover the front surface of the radiator 36. The radiator cover 37 prevents sand or pebbles jumped up by the front wheel 14 from directly hitting the radiator 36.

39 is a resin cowling, this cowling 39 is a front cowl 40 that covers the upper front of the front fork 13,
The front cowl 40 has a left side cowl 41 and a right side cowl 42 extending rearward from left and right outer edges. 43 is a windshield.

The fuel tank 27 will be described in more detail with reference to FIGS. 1, 3, and 4.
Has an upper U-shaped upper plate 45 and a lower plate 46 facing up and down, viewed from the front, and the upper and lower plates 45, 46 are welded with their outer edges joined in a middle state, Thereby, the fuel tank 27 is formed. A recess 47 is formed on the upper surface of the upper plate 45, and a fuel injection pipe 48 is welded to the recess 47, and a cap 49 for opening and closing the injection pipe 48 is provided. In addition, reference numeral 50 denotes a support for supporting the fuel tank 27 on the main frame 4.

The left and right lower ends 56 and 57 of the fuel tank 27 extend gradually away from each other as they move forward. On the other hand, left and right side cowls extending from the front cowl 40
The rear upper edges of 41 and 42 are joined to the outer surfaces of the left and right lower ends 56 and 57, respectively. In this case, a step surface 58 is formed on each of the outer surfaces of the left and right lower ends 56 and 57 as shown in FIG. 4, and the rear upper edges of the side cowls 41 and 42 are formed on the step surface 58. I'm stuck. That is, as a result, the outer surfaces of the side cowls 41 and 42 are substantially flush with the outer surfaces of the left and right lower ends 56 and 57.

1 to 3, the exhaust pipe 25 will be described in more detail. The exhaust pipe 25 has an extension pipe 52 that temporarily extends forward and downward from the engine 21 and extends leftward, and a horizontal pipe 53 that extends further rightward from the lower end of the extension pipe 52. Have. Further, an expansion chamber 54 is provided which extends upward from the right end of the horizontal pipe 53 and is bent rearward, and the rear end of the expansion chamber 54 is connected to the silencer 26 described above.

The expansion chamber 54 has a larger diameter than the extension pipe 52 and the horizontal pipe 53. The expansion chamber 54 has a left half cylinder 59 and a right half cylinder 60 facing each other in the vehicle width direction.
The outer peripheral portions of the 59 and 60 are joined in the middle and welded, thereby forming the expansion chamber 54.

A joint 62 between outer edges of the upper plate 45 and the lower plate 46 at the lower end 57 on the right side, and a joint 63 between outer edges of the left half cylinder 59 and the right half cylinder 60 on the upper surface of the expansion chamber 54. Extend substantially in parallel with each other, and these two joints 62 and 63 are overlapped with each other in the vehicle width direction. In this case, the joint 62 at the lower end 57 on the right side is positioned outside the joint 63 on the upper surface of the expansion chamber 54 with a slight gap therebetween in the vehicle width direction. Contact is prevented.

Right side cowl extending from the front cowl 40
The rear lower edge of 42 extends along this joint 63 with a slight gap from the joint 63 in the expansion chamber 54, that is, the outer surface of the expansion chamber 54 also functions as a part of the cowling 39. doing. The lower rear edge of the right side cowl 42 is formed at a position higher than the rear lower edge of the left side cowl 41.

By the way, as shown by the dashed line in FIG. 4, in the conventional configuration, the lower left end (not shown) and the lower right end 57 'of the fuel tank extend so as to gradually approach each other as they move forward. This is to prevent the lower surface of the lower plate 46 'in the fuel tank from being easily viewed from the front. Then, according to this configuration, the joint 62 ′ at the lower right end 57 ′ crosses the joint 63 on the upper surface of the expansion chamber 54. Therefore, the lower end 57 'on the right side and the expansion chamber
In order to avoid contact with the upper surface of 54, it is necessary to separate them up and down to form a gap between them. As a result, as described in the related art, there is a problem that a sense of unity cannot be obtained between the fuel tank and the expansion chamber 54.

However, in the above embodiment, since the front side of the fuel tank 27 is covered with the cowling 39, the lower side of the lower plate 46 is not easily viewed from the front when viewed from the front. In addition, there is no problem even if the shape gradually separates as the left and right lower ends 56 and 57 move forward, that is, the joint 62 at the right lower end 57 is substantially parallel to the joint 63 at the upper surface of the expansion chamber 54. The two joints 62 and 63 are overlapped in the vehicle width direction.

(Effects of the Invention) According to the present invention, the joint between the outer edges of the upper plate and the lower plate at the lower end of one side of the fuel tank, and the left half cylinder and the right half on the upper surface of the front and rear halfway of the exhaust pipe Since the joint portion of the outer edge portion of the cylinder and the outer edge portion are overlapped in the vehicle width direction, when the fuel tank and the front and rear halfway portion of the exhaust pipe are viewed from the side,
There will be no gap between these two. Therefore, a sense of unity in appearance can be obtained between the two, which is beneficial in terms of appearance of the vehicle body.

In addition, the fuel tank can be made to approach the front and rear halfway by an amount equivalent to the overlapping of the two joints as described above. For this reason, the concentration of the mass and the lowering of the center of gravity can be achieved, so that the improvement of the maneuverability is achieved.

[Brief description of the drawings]

1 shows an embodiment of the present invention. FIG. 1 is a partially enlarged partial sectional view of FIG. 2, FIG. 2 is an overall side view of a motorcycle, FIG.
FIG. 4 is a sectional view taken along the line III-III of FIG. 1, and FIG.
FIG. 4 is a view taken along line IV-IV in FIG. 1 ... motorcycle, 2 ... body frame, 21 ... engine, 25 ... exhaust pipe, 27 ... fuel tank, 45 ... top plate, 46
…… Lower plate, 54… Expansion chamber (midway of front and rear), 57 …… Right lower end (one side lower end), 59 …… Left half cylinder, 60… Right half cylinder, 62 …… Junction , 63 ... The joint.

Claims (1)

(57) [Claims] An inverted U-shaped fuel tank is provided so as to straddle a vehicle body frame, and the fuel tank is formed by facing the fuel tank up and down and joining outer edges of a lower plate. Outer edges of left and right half cylinders in which the front and rear halfway portions of the exhaust pipe extending rearward from the engine are located below the lower end of one side of the fuel tank, and the front and rear halfway portions face each other in the vehicle width direction. In the motorcycle formed by joining together, in the lower end of one side portion of the fuel tank, the joining portion between the outer edges of the lower plate and the left and right half cylinders on the upper surface of the front and rear halfway portion of the exhaust pipe. The body structure of a motorcycle in which the outer edges are joined together in the vehicle width direction.