JPH0569756B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exhaust pipe device applied to a two-wheeled motor vehicle or a three-wheeled vehicle equipped with a liquid-cooled two-stroke engine near the center of the vehicle body.

(Background of the Invention) In motorcycles and tricycles that have a two-stroke engine mounted near the center of the vehicle body, it is necessary to appropriately select the length and thickness of the exhaust pipe in order to improve the output performance of the engine. . In conventional vehicles of this type, an exhaust pipe extends forward and downward from an exhaust hole in the front of the engine, and this exhaust pipe is guided rearward through the bottom or side of the engine. However, in this case, even if performance could be improved by making the overall length of the exhaust pipe longer, improvements in engine performance are limited because the exhaust pipe cannot be made any longer. There was a problem.

In addition, in a two-stroke engine, in order to fully utilize the pulsation of exhaust gas (cadenacy effect), it is necessary to provide a large-diameter expansion pipe in the middle of the exhaust pipe. However, in conventional devices, the installation position of the expansion pipe is limited in order to avoid interference with equipment placed close to the exhaust pipe, such as an air cleaner or carburetor, and the selection of the location of the expansion pipe or exhaust pipe is difficult. There was also the problem of reduced freedom. Therefore, it was considered to move the exhaust pipe back and forth in the width direction of the vehicle in front of the engine, and then guide it to the rear through the upper side of the engine (Japanese Patent Laid-Open No. 140224/1983).

Here, the exhaust pipe usually becomes a large-diameter expansion pipe near the side of the engine. However, when a radiator is disposed in front of the expansion pipe in a liquid-cooled engine, a problem arises in that it becomes difficult for the traveling wind to hit the expansion pipe.

(Object of the Invention) The present invention has been made in view of the above circumstances, and includes guiding an exhaust pipe rearward from the front of the engine through the upper side of the engine, and connecting the exhaust pipe to the expansion pipe near the side of the engine. An object of the present invention is to provide an exhaust pipe device for a vehicle that can improve cooling performance by making it easier for traveling air to hit the expansion pipe when the radiator is disposed in front of the expansion pipe.

(Structure of the Invention) According to the present invention, this purpose is achieved by reciprocating one steering front wheel, a liquid-cooled two-stroke engine mounted near the center of the vehicle body, and reciprocating the engine in the width direction of the vehicle body in front of the engine. In an exhaust pipe system for a vehicle, the exhaust pipe system includes an exhaust pipe extending rearward through the upper side of the engine and serving as an expansion pipe near the side of the engine, and a radiator disposed in front of the expansion pipe. A pair of right and left attenuation tubes extending obliquely downward and rearward from the radiator through above the radiator and the engine, and a tank mounted from above so as to straddle both attenuation tubes with a sufficient distance between the radiator and the radiator. This is achieved by an exhaust pipe device for a vehicle, comprising: a tank-shaped container, and is configured to guide running wind to the expansion pipe from between the bottom surface of the tank-shaped container and the radiator.

(Example) Fig. 1 shows an example of the application to a tricycle for running on rough terrain and a side view, Figs. 2 and 3 show a front view and a plan view of the main parts, and Fig. 4 shows the installation of a tricycle installed in the running air intake. FIG. 5 is a perspective view of the baffle plate shown in FIG.

In FIG. 1, reference numeral 10 denotes a frame, including a steering shaft tube 12 at the front end, a pair of left and right upper tubes 14, 14a, 14b, a down tube 16, a pair of left and right lower tubes 18 (only one is shown), and a seat rail 20. , a backup tube 22, etc. A liquid-cooled engine 24 is mounted in a space surrounded by an upper tube 14 and a lower tube 18. A carburetor 26 is connected to the rear surface of the cylinder 24a of the engine 24, and intake air is guided to the carburetor 26 from an air cleaner 28 attached to the upper tube 14 via a duct 30. Here, the air purifier 28 serves as a tank-like container in the present invention, and includes both hot tubs 14a,
It is attached from above so as to straddle 14b. 32 is an element installed within the air cleaner 28.

Reference numeral 34 denotes an exhaust pipe, which extends from the front of the cylinder 24a to the left side of the engine 24, between a pair of left and right rear wheels 36 (only one is shown), and connects to an exhaust muffler 38 disposed between both rear wheels 36. It is connected. Here, the front part of the exhaust pipe 34 is bent in front of the down tube 16 so as to reciprocate in the vehicle width direction so as not to overlap when viewed from the front. That is, the exhaust pipe 34 extends obliquely forward and downward from the exhaust hole located on the front surface of the cylinder 24a, is bent to the right in front of the down tube 16, is bent downward, extends to the left, and then diagonally rearward and upward. Bent engine 2
Pass through the side of 4. In this way, the exhaust pipes 34 are bent counterclockwise around the exhaust hole of the cylinder 24a when viewed from the front so that they do not overlap each other, so that the wind is directed toward the vicinity of the cylinder connection part of the exhaust pipe 24, where the temperature is high. This results in good cooling, resulting in good cooling performance.

Further, since the exhaust pipe 34 is sufficiently long, the diameter can be increased from the vicinity of the down tube 16 to form an expansion pipe. Therefore, the diameter can be made sufficiently small near the bottom of the carburetor 26 and the driver's seat 42. Since the overall length of the exhaust pipe is increased in this way, the degree of freedom in determining the position of the expansion pipe increases, and the diameter of the exhaust pipe can be made sufficiently small in the portion close to equipment such as the carburetor.

40 is a rear fender that covers above both rear wheels 36. On this fender 40 is the air purifier 28.
A driver's seat 42 is attached that extends up to .

A pair of left and right radiators 4 are installed in the down tube 16.
4, 44a, and 44b are attached so as to sandwich the down tube 16 from the left and right sides. Air fans 46, 46a, and 46b are attached to the front surface of the radiator 44. The air baffle 46 includes a plurality of vertically elongated air baffles 48, 48a, and 48b, and each baffle plate 48 is inclined so that its front edge is deviated toward the center of the vehicle body (see FIG. 5). Incidentally, by tilting the front edge of the baffle plate 48 inward, it is possible to prevent mud and water splashed up by the front wheels 50 described later, particularly mud and water splashed up during steering, from adhering to the radiator 44. .
In addition, mud and water adhering to the air guide plate 48 fall along the air guide plate 48 due to vibrations during driving, so the air guide plate 48
It can also prevent the water from becoming clogged with mud.

Note that the left radiator 44a is located near the upper side of the engine 24 where the exhaust pipe 34 expands, that is, in front of the expansion pipe. radiator 44a here
is sufficiently away from the lower surface of the air cleaner 28, which is attached to straddle the upper tubes 14a and 14b, and a sufficiently large distance is ensured between the radiator 44a and the air cleaner 28.

50 is a front wheel equipped with a wide ultra-low pressure tire. This front wheel 50 includes a pair of left and right front forks 52,
It is attached to the lower part of 52a and 52b. The upper end portion of the front fork 52 is fixed to the upper and lower ends of a steering shaft (not shown) rotatably held in the steering shaft cylinder 12 via upper and lower brackets 54, 54a, and 54b. There is. In FIG. 1, 56 is a front fender attached to the lower surface of the lower bracket 54b, and 58
is a steering handle fixed to the upper surface of the upper bracket 54a.

60 is a headlamp as a lamp. This headlamp 60 includes a horizontally long case, and a pair of left and right light emitting parts 62, 62a, 62b (see FIG. 2) and reflectors 64, 64a, 64b are housed in this case. It is arranged in the upper part of the space surrounded by both front forks 52 and upper and lower brackets 54 so that axes A and B (see FIG. 3) pass between the steering shaft cylinder 12 and each front fork 52a and 52b. will be established. For this purpose, a running wind intake 66 (FIG. 1) that opens toward the front is formed in the lower part of the space.

In this embodiment, a wind blower 68 is installed to guide the traveling wind entering the traveling wind intake 66 toward the radiator 44 and the engine 24. As shown in FIG. 4, this air blower 68 includes a pair of guide plates 70, 70a with a semicircular cross section, which are in close contact with the front fork 52.
70b, and a plurality of baffle plates 72 that connect between the guide plates 70. An arcuate notch 74 is formed at the rear edge of the baffle plate 72 to prevent interference with the steering shaft cylinder 12. The air blower 68 is attached to the upper and lower brackets 54
With one of the forks removed, it is pushed between both front forks 52 and held between the upper and lower brackets 54.

In this embodiment, the exhaust pipe 34 exits the exhaust hole of the cylinder 24 and is bent so as to pass below this exhaust hole in the width direction of the vehicle body, and the lower edge of the front fender 56 and the radiator 44 are placed above this exhaust hole. It is located in For this reason, the wind from the vehicle is not obstructed by the front fender 56 or the radiator 44 and hits the exhaust pipe 34 well, thereby further improving the cooling performance of the exhaust pipe 34.

(Effects of the Invention) As described above, although the expansion pipe of the exhaust pipe is passed through the upper side of the engine and the radiator is disposed in front of the expansion pipe, the radiator and the tank-like structure above the radiator are disposed in front of the expansion pipe. The traveling wind that enters the gap between the container and the lower surface of the container can be guided to the expansion pipe on the upper side of the engine by the mask of this tank-like container. This makes it easier for the traveling wind to hit the expansion pipe portion located at the rear of the radiator, thereby improving its cooling performance.

[Brief explanation of the drawing]

Figure 1 is a side view of an embodiment applied to a tricycle for traveling on rough terrain, Figures 2 and 3 are front and plan views of its main parts, and Figure 4 is a wind guide plate installed at the air intake for traveling. FIG. 5 is a sectional view taken along the - line in FIG. 1. 12... Steering shaft tube, 14... Atsupachi tube,
24...Liquid-cooled two-stroke engine, 24a...
Cylinder, 28...Air purifier as a tank-like container, 44a...Radiator.

Claims (1)

[Scope of Claims] 1. One steering front wheel, a liquid-cooled two-stroke engine mounted near the center of the vehicle body, and the engine is reciprocated in the width direction of the vehicle body in front of the engine, and then the upper side of the engine is moved back and forth in the width direction of the vehicle body. An exhaust pipe device for a vehicle, comprising: an exhaust pipe extending rearward through the engine and serving as an expansion pipe near the side of the engine; and a radiator disposed in front of the expansion pipe. A pair of left and right attenuation tubes passing above the engine and extending diagonally rearward, and a tank-shaped container attached from above so as to straddle both attenuation tubes with a sufficient distance between them and the radiator; An exhaust pipe device for a vehicle, characterized in that running wind is guided to the expansion pipe from between a bottom surface of a tank-like container and the radiator.