JPH0352632Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an exhaust pipe that is compactly arranged on the side of a motorcycle body without protruding laterally.

Prior Art Conventionally, in motorcycles, the cross-sectional area of the exhaust pipe is gradually increased from the exhaust pipe inlet toward the longitudinal center of the exhaust pipe during the scavenging period (2-cycle engine) or during the exhaust period (4-cycle engine). By keeping the pressure at the exhaust pipe inlet of the engine (engine) at negative pressure and drawing out the exhaust gas to improve scavenging or exhaust efficiency, and by reducing the cross-sectional area of the exhaust pipe from the latter half of the longitudinal center of the exhaust pipe toward the exhaust pipe outlet. , generates a reflected wave in the exhaust pipe, and uses this reflected wave to make the pressure at the exhaust pipe inlet positive at the end of the exhaust, pushing back the fresh air that would otherwise be blown through, and this Kadenashi effect significantly improves the scavenging or exhaust efficiency. I was trying to increase it.

The cross-sectional shape of such an exhaust pipe is usually approximately circular.

Problems to be Solved by the Invention In the above conventional technology, since the exhaust pipe is approximately circular, it has sufficient strength against fluctuations in the exhaust gas passing through the interior as described above. When trying to make the car body structure more compact and reduce running air resistance as much as possible, the exhaust pipe, which had a circular cross section, bulged out in the width direction of the car body, creating a problem.

The present invention aims to provide an exhaust pipe structure that eliminates these drawbacks.

Means and Effects for Solving the Problems In accordance with the above-mentioned object, the present invention has been developed so that the cross-sectional area of the exhaust pipe gradually increases from the exhaust pipe inlet to the longitudinal center of the exhaust pipe, and from the latter half of the longitudinal center of the exhaust pipe to the exhaust pipe. The cross-sectional area of the exhaust pipe decreases towards the exit,
The reduced end portion is connected to a silencer, and in an exhaust pipe disposed on the side surface of the vehicle body of a motorcycle, both side wall surfaces on the vehicle body width side of the exhaust pipe are made into a planar shape, and the cross-sectional shape of the exhaust pipe is made into a planar shape. The flat wall is formed to be long in the vertical direction with the long side being the long side, and the flat wall is arranged parallel to the rocking plane of the rear wheel and outward from the upper side of the rear wheel, thereby reducing the vehicle body width. Both sides of the car body width side are formed in a flat shape, and the exhaust gas expands and contracts inside the exhaust pipe, which has a cross section that is long in the vertical direction with these walls as the long sides, and is directed toward the rear silencer. once flows.

Embodiment An embodiment of the present invention illustrated in FIGS. 1 to 3 will be described below.

In FIG. 1, a pair of left and right exhaust pipes 3 connected to an exhaust port 2 of an engine 1 are disposed inside a center pillar 10 and a backstay 11, and are curved to the level of a seat rail 12. It extends beyond the rear end of the rail 12, and the silencer 4 is connected to the extended end.

Furthermore, the exhaust pipe 3 and silencer 4 are
It is located inside the side cover 14 and the rear cowling 15, and is arranged so as to sandwich the rear wheel 13 from the left and right without interfering with the rear wheel 13.

Further, in the exhaust pipe 3, the opposing side walls 3a on the vehicle body width side are formed in a planar shape, and the upper and lower walls 3b are formed in the shape of a semicircular tube, and the cross-sectional shape is oval with the side wall 3a as the long side. made into a shape,
Moreover, the vertical width of the exhaust pipe 3 gradually increases from the inlet toward the center in the longitudinal direction, and decreases from the latter half of the center in the longitudinal direction toward the exhaust pipe outlet, and as a result, the cross-sectional area of the exhaust pipe also increases as described above. Similarly, the scavenging or evacuation efficiency due to the Kadenashi effect is now significantly increased.

Furthermore, a plurality of left and right pairs of slits 3c are formed at approximately midpoint between the upper and lower sides of both side walls 3a of the exhaust pipe 3 at intervals along the longitudinal direction, and a narrow reinforcing plate is inserted into the pair of slits 3c. 3d is inserted and welded to connect and reinforce both side walls 3a (see FIGS. 2 and 3).

The embodiment shown in FIGS. 1 to 3 is constructed as described above, and the opposite side wall 3a on the vehicle body width side of the exhaust pipe 3 is formed into a planar shape, and the cross-sectional shape is shaped like an oval elongated vertically. Because it was made into
Compared to the conventional exhaust pipe P (double-dashed line in Fig. 2), which has an oval cross-section, the amount of protrusion in the vehicle width direction is l ₂
−l ₁ (where l ₁ is the distance between the front and outer wall surfaces of the pair of left and right exhaust pipes 3 in the embodiment, l ₂ is the distance in the conventional exhaust pipe P).

Further, by forming the exhaust pipe 3 into a shape having the flat portion, it becomes easy to attach a support member for fixing the exhaust pipe 3 to the vehicle body frame.

On the other hand, by constructing a plurality of reinforcing plates 3d at intervals along the longitudinal direction between the opposing side walls 3a of the exhaust pipe 3, a planar The side wall 3a can be reinforced to improve rigidity, and vibrations caused by pulsating waves of positive and negative pressure generated in the exhaust pipe 3 can be effectively prevented.

Furthermore, since the exhaust pipe 3 is arranged inside the side cover 14 and the rear cowling 15, the outside is smart.

In the above embodiment, the slit 3c was formed in the side wall 3a of the exhaust pipe 3, and the reinforcing plate 3d was inserted into the same part and welded. However, as shown in FIG. In the case of the exhaust pipe 23 made by combining the upper and lower members with the flange 23a, by cutting out a part of the flange 23a, a gap for inserting the reinforcing plate 23d can be obtained. , reinforcing plate 2
Just insert and weld 3d.

In addition, as shown in FIGS. 5 and 6, if a reinforcing plate 33d having a small protrusion 33e at one end is installed between large and small slits 33c formed on opposite side walls 33a of the exhaust pipe 33, The shoulder portion 33f engages with the inner surface of the side wall 33a, further improving the reinforcing effect and improving ease of assembly.

Effects of the invention The present invention makes both side walls of the exhaust pipe on the vehicle body width side planar, and its cross-sectional shape is formed to be elongated in the vertical direction with the planar side walls as the long sides. Because it is located parallel to the dynamic plane and outside of the upper side of the rear wheel, the width of the vehicle body can be reduced without significantly changing the cross-sectional area of the exhaust pipe, compared to conventional exhaust pipes with a generally circular cross section. As a result, the front projected area of the vehicle body can be reduced without degrading the exhaust function, and running air resistance can be significantly reduced. Moreover, the entire vehicle body can be configured compactly.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of a motorcycle equipped with an exhaust pipe according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing the correspondence relationship between the exhaust pipe of the embodiment and the conventional exhaust pipe, as well as the rear wheel. 3 is a cross-sectional view taken along the - line in FIG. 1, FIG. 4 is a sectional view similar to FIG. 3 of an exhaust pipe according to another embodiment, and FIG. 5 is an explanation of an exhaust pipe according to still another embodiment. 6 is a vertical sectional view of FIG. 5, and FIG. 7 is an explanatory view of the same main part. 1...Engine, 3...Exhaust pipe, 3a...Side wall, 4...Silencer, 12...Seat rail, 13...Rear wheel, 23...Exhaust pipe, 3
3...exhaust pipe, 33a...side wall.

Claims (1)

[Scope of utility model registration request] The cross-sectional area of the exhaust pipe gradually increases from the exhaust pipe inlet to the longitudinal center of the exhaust pipe, and decreases from the latter half of the longitudinal center of the exhaust pipe to the exhaust pipe outlet, and the decreasing end is used as a silencer. In an exhaust pipe that is connected to a side surface of a motorcycle and is arranged on the side of a motorcycle, both side walls on the width side of the vehicle body of the exhaust pipe are made flat, and the cross-sectional shape is vertically arranged with the long side of the flat wall. What is claimed is: 1. An exhaust pipe for a motorcycle, characterized in that the exhaust pipe is elongated in the direction of the rear wheel, and the flat wall is parallel to the swinging plane of the rear wheel and disposed outward from above the side surface of the rear wheel.