JPH0328091A - Exhaust pipe device of car - Google Patents

Abstract

PURPOSE:To enhance the output of an engine, increase the degree of freedom in locating an expansion pipe and an exhaust pipe, and enhance the cooling characteristic of this exhaust pipe by leading it out ahead the front face of the engine, reciprocating in the direction across the width of vehicle body so as not to overlap ahead a down tube, and threading beside the engine backward. CONSTITUTION:An exhaust pipe 34 leading from the front face of a cylinder 24a is passed on the left of an engine 24, extended to between a left and a right rear wheel 36, and connected with an exhaust silencer 38 arranged between these two rear wheels 36. Therein the front of this exhaust pipe 34 is folded in reversals across the vehicle width so as not to overlap in front of a down tube 16 when viewed from ahead. That is, the exhaust pipe 34 is stretched to ahead aslant downward from an exhaust hole located in the facade of the cylinder 24a, folded to the right at the front face of the down tube 16, then folded back downward, stretched to the left, further folded up aslant backward, and threaded through the engine 24. Because this exhaust pipe 34 is sufficiently long, its dia. can be increased from a point near the down tube 16 so as to form an expansion pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exhaust pipe device applied to a motorcycle or tricycle equipped with a 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, in order to improve the output performance of the engine,
It is necessary to appropriately select the length and thickness of the exhaust pipe. 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.

(Objective of the Invention) The present invention was made in view of the above circumstances, and it is an object of the present invention to improve the output of a two-stroke engine by making the exhaust pipe sufficiently long, and to increase the degree of freedom in determining the positions of the expansion pipe and the exhaust pipe. ,
Furthermore, it is an object of the present invention to provide an exhaust pipe device for an engine in which the cooling performance of the exhaust pipe is not likely to deteriorate.

(Structure of the Invention) According to the present invention, the object is to provide an exhaust pipe system for a vehicle having one steering front wheel, a two-stroke engine mounted near the center of the vehicle body, and an exhaust pipe connected to the engine. In the above, the exhaust pipe is formed so as to extend forward from the front of the engine, reciprocate in the width direction of the vehicle body so as not to overlap in front of the down tube so as not to overlap when viewed from the front, and further to be guided rearward through the side of the engine. This is achieved by a vehicle exhaust pipe device characterized by: (Example) Fig. 1 is a side view of an embodiment applied to a tricycle for traveling on rough terrain, Figs. 2 and 3 are front views and plan views of the main parts, and Fig. 4 is a side view of an embodiment applied to a tricycle for traveling on rough terrain. A perspective view of the baffle plate shown in Fig. 1.
It is a sectional view taken along the line v-v in the figure.

In FIG. 1, reference numeral 10 denotes a frame, which includes a steering shaft cylinder 12 at its front end, a pair of left and right attachment tubes 14 (14a,
14b), a down tube 16, a pair of left and right lower tubes 18 (only one shown), a seat rail 20, a back tube 22, and the like. 24 is a liquid-cooled engine,
It is mounted in a space surrounded by the atsupa tube 14 and 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 through a duct 30.

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 the two 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 further diagonally rearward and upward. It is bent and passes along the side of the engine 24. In this way, the exhaust pipes 34 are bent counterclockwise around the exhaust hole of the cylinder 24a when viewed from the front so as not to overlap each other, so that the exhaust pipe 34, which has the highest temperature, passes through the running air.
This means that the area near the cylinder connection part 4 will be well hit, and its cooling performance will be good. Further, since the exhaust pipe 34 is sufficiently long, the diameter can be increased from near the down tube 16 to serve as an expansion pipe. Therefore, the diameter can be made sufficiently small near the bottom of the carburetor 26 and the operating seat 42. This longer overall length of the exhaust pipe increases the degree of freedom in determining the position of the expansion pipe, and the diameter of the exhaust pipe can be made sufficiently small in the area close to equipment such as the carburetor, allowing for greater flexibility in the arrangement of the exhaust pipe. degree increases.

40 is a rear fender that covers above both rear wheels 36. An operating seat 42 is mounted on the fender 40 and extends to the air cleaner 28.

A pair of left and right radiators 44 (4
4a, 44b) are attached to sandwich the down tube 16 from the left and right sides. An air blower 46 (46a, 46b) is attached to the front surface of the radiator 44. The air guide 46 includes a plurality of vertically elongated air guide plates 48 (48a, 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). In addition, the air guide plate 48
By tilting the front lines inward, it is possible to prevent mud and water splashed up by the front wheels 50, particularly mud and water splashed up during steering, from adhering to the radiator 44. In addition, mud and water adhering to the wind guide plate 48 are removed by vibrations during driving.
Since the mud falls along the same direction, it is possible to prevent the wind blower 46 from becoming clogged with mud.

50 is a front wheel equipped with a wide ultra-low pressure tire. This front wheel 50 has a pair of left and right front forks 52 (5 2 a,
5 2 b).

The upper end 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, 54b). ing. 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 6 are provided inside the case.
2 (62a, 62b, see Figure 2) and a reflector 64
(64a, 64b) are accommodated, and both front forks 5 are arranged so that optical axes A and B (see FIG. 3) of both light emitting parts 62 pass between the steering shaft cylinder 12 and each front fork 52a, 52b.
2 and the upper and lower brackets 54. For this reason, a running wind intake 66 (FIG. 1) that opens toward the front is formed in the lower part of this space.

In this embodiment, a wind blower 68 guides the traveling wind entering the traveling wind intake 66 toward the radiator 44 and the engine 24.
is installed. As shown in FIG. 4, this air baffle 68 includes a pair of guide plates 70 (70a, 70b) with a semicircular cross section that are in close contact with the front fork 52, and a plurality of baffle plates 72 that connect 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 pushed between both front forks 52 with one of the upper and lower brackets 54 removed,
It is supported between the upper and lower brackets 54.

In this embodiment, the exhaust pipe 34 exits the exhaust hole of the sill 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, the present invention extends the exhaust pipe forward from the front surface of the cylinder, and extends the exhaust pipe forward from the front of the down tube as viewed from the front. Since the exhaust pipes are reciprocated in the vehicle width direction so as not to overlap, and then guided rearward through the sides of the engine, the overall length of the exhaust pipe can be ensured to be sufficiently long, making it possible to improve engine output. Furthermore, since the overall length of the exhaust pipe is increased, the position of the expansion pipe provided in the middle of the exhaust pipe can be freely determined, and the degree of freedom in selecting the position of the expansion pipe is increased. Therefore, it is possible to make the diameter of the exhaust pipe sufficiently small in the portion that approaches equipment such as an air cleaner or a carburetor, and the degree of freedom in the arrangement of the exhaust pipe is increased.

Furthermore, since the exhaust pipes are bent so that they do not overlap when viewed from the front, they are well exposed to airflow while the vehicle is running, improving cooling performance.

[Brief explanation of the drawings] Figure 1 is a side view of an embodiment applied to a tricycle for traveling on rough terrain, Figures 2 and 3 are front views and plan views of its main parts, and Figure 4 is a traveling windshield. A perspective view of the baffle plate installed at the entrance, Figure 5 is the first
It is a sectional view taken along the line V-V in the figure. 24...Engine, 24a...Cylinder, 34...Exhaust pipe.

Claims (1)

[Claims] In an exhaust pipe device for a vehicle having one steering front wheel, a two-stroke engine mounted near the center of the vehicle body, and an exhaust pipe connected to the engine, the exhaust pipe is directed forward from the front surface of the engine. An exhaust pipe device for a vehicle, characterized in that the exhaust pipe device is formed so as to extend back and forth in the width direction of the vehicle body so as not to overlap in front of the down tube so as not to overlap when viewed from the front, and further to be guided rearward through the side of the engine.