JPH01151707A - Exhaust device of motorcycle - Google Patents

Abstract

PURPOSE:To prevent a motorcycle itself and other motorcycles from being polluted by exhaust drain from the motorcycle itself by arranging a drain exhaust hose connected to the rear and lower part of an exhaust pipe, through a space above a rear wheel, inside a license bracket, and forming an opening downward therefrom. CONSTITUTION:A tail cowl 7 is provided behind the passenger seat 6 of a motorcycle, while a mud guard 10 and a license bracket 11 are installed below those components respectively. Further, below them are disposed the tapered pipe 17b and the straight pipe 17c of a muffler pipe composing an exhaust pipe respectively. A drain exhaust hose 25 is connected to a short pipe 24, which is connected to the straight pipe 17c in this constitution. The drain exhaust hose 25 is arranged inside a license supporting part 11b through the inner part of a direction indicator 26 attached on the license bracket 11, then the rear end opening of the hose is arranged on the lower end of the license supporting part 11b.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to an exhaust system for a motorcycle that discharges exhaust gas from an engine to the rear of the vehicle. It relates to a structure for preventing accumulation in a pipe.

[Conventional technology]

Exhaust gas from an engine contains a large amount of water vapor, and some of this water vapor is exhausted outward as steam, but the rest usually flows through the exhaust pipe toward the rear of the vehicle. As the temperature drops during this time, it condenses and accumulates near the rear end of the exhaust pipe without being discharged outward. In particular, in the case of a two-stroke engine, since the exhaust gas temperature is low and the exhaust gas contains a large amount of oil, there is a tendency for blackish brown drain containing oil to accumulate in the condensed water. If this condensate is allowed to accumulate, when the engine is operated at high speeds and under high load when starting after waiting at a traffic light, this condensate may be blown out backwards all at once, causing problems such as staining the following vehicles, etc. There is.

Conventionally, in order to prevent condensate from accumulating too much in the exhaust pipe, a drain discharge hose is connected to the exhaust pipe, and the hose is placed vertically between the main pipe and the seat rail of the vehicle body frame. There is an exhaust device that is routed along the backstay and opens near the pivot portion of the rear arm. According to this exhaust system, since almost no condensate accumulates in the exhaust pipe, the condensate does not blow out rearward from the rear end of the exhaust pipe all at once, and the problem of staining the following vehicle etc. can be solved.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional exhaust system, the exhaust hose is opened near the pivot of the rear arm, so the rear arm, drive chain, rear wheel, etc. are easily soiled, and in the case of a two-person motorcycle, the exhaust hose is opened near the pivot of the rear arm. There is a problem in that the feet of seat occupants are easily soiled. Furthermore, since the discharge hose is routed along the backstay, it is easily visible and has the problem of deteriorating the appearance.

The purpose of the present invention is to solve the above-mentioned problems of the conventional exhaust system.
It can prevent not only the following vehicle but also the motorcycle itself from getting dirty.
Furthermore, it is an object of the present invention to provide an exhaust system for a motorcycle that can suppress deterioration in appearance.

[Means for solving problems]

The present invention provides an exhaust system for a motorcycle in which the exhaust pipe is arranged at the upper side of the vehicle, in which a drain discharge hose is connected to the rear lower surface of the exhaust pipe, and the hose is arranged inside the license bracket by passing above the rear wheel. It is characterized by having an opening at the bottom of the bracket.

Here, the rear part of the exhaust pipe in the present invention refers to a position where the exhaust gas temperature drops and water vapor tends to condense and accumulate as a drain, and is generally near the final stage expansion chamber.

[Effect]

According to the exhaust system of the present invention, condensate hardly accumulates in the exhaust pipe, and condensate does not blow out backwards all at once even during high-speed, high-load operation, so there is no problem of contaminating following vehicles, etc. can be resolved. In this case, the generated drain is discharged downward from near the bottom of the license bracket through the drain discharge hose, so the drain does not adhere to the rear arm or the like of this motorcycle or the rear seat occupant, and the above-mentioned conventional method This also solves the problem of staining the motorcycle itself.

Furthermore, since the exhaust hose of the present invention only needs to be routed between the rear part of the exhaust pipe and the license bracket disposed close to this, the length of the exhaust hose can be shortened. Since the latter half of the exhaust hose is hidden within the license bracket, it is not very noticeable, so the problem of poor appearance can be reduced.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

1 to 6 show an exhaust system according to an embodiment of the present invention, in which 1 is a motorcycle equipped with the exhaust system of this embodiment, and its body frame 2 is of a so-called double cradle type. At the front end of the main pipe 2C of the vehicle body frame 2, a front fork 4, which rotatably supports the front wheel 3 at its lower end, is supported so as to be rotatable left and right. The front end of the seat rail 2a arranged at
A backstay 2b is diagonally arranged and fixed between the main pipe 2C and the main pipe 2C. A fuel tank 5 is mounted near the connection part of the seat rail 2a, and a two-person seat 6 is mounted behind this, and a tail cowl that covers the rear of the vehicle is arranged behind the seat 6. . Further, at the lower rear end of the main pipe 2C, a rear arm 9, which pivotally supports the rear wheel 8 at the rear end, is pivotably supported up and down.

Above the rear wheel 8, a front mudguard 10 and a rear mudguard part 1)a, which is the front half of the license bracket 1), are arranged so as to cover it, and the rear mudguard part 1)m is connected to the tail cowl. Located within.

Further, the license support portion 1)b, which is the rear half of the license bracket 1), extends downward so as to be continuous with the tail cowl. This license support part 1)b has a substantially U-shaped cross section and is located at the rear end of the vehicle.A tail light 12 is attached to the upper part of the license support part 1)b, and a license plate 13 is attached to the center part.

A water-cooled two-stroke, two-cylinder engine unit 14 is mounted approximately in the middle of the vehicle body frame 2.

What about each engine unit 14? Exhaust pipes 15 for discharging exhaust gas toward the rear of the vehicle are connected to the exhaust ports of the iJs 14a, respectively.

Each exhaust pipe 15 is an expansion pipe 1 connected to the exhaust port.
6 and a muffling pipe 17 connected thereto. The expansion pipe 16 crosses the connecting pipe part 16a connected to the exhaust port left and right, and the chamber part 16b continues therefrom.
(first expansion chamber) is raised up to near the lower edge of the fuel tank 5 and further bent approximately horizontally rearward.

Note that 16C is a protector that protects the thigh of the driver Ml.

Further, the muffling pipe 17 includes a connecting pipe portion 17a, a Taber pipe portion 17b, and a straight pipe portion 17c extending rearward near the lower edge of the seat 6, and the outside of the connecting pipe portion 17a is covered with a side cover 18. A protector 19 is attached to the outside of the straight pipe portion 17c to protect the vicinity of the thighs of the rear seat occupant M2 and to improve the appearance. Also, inside the rear end of this straight pipe portion 17C, there is a substantially semicircular shielding plate 17d.
is fixed by welding, and this is to prevent the surrounding area from being contaminated by exhaust gas.

The inside of the straight pipe portion 17e is located at the first. Second partition wall 20a.

20b, the upstream side of the first partition wall 20a is a second expansion chamber 21a, the downstream side of the second partition wall 20b is a third expansion chamber 21b, and the portion between both corner walls 20a and 20b is a fourth expansion chamber 21c. They are respectively. The second expansion chamber 21a and the third expansion chamber 21b are connected by a first communication pipe 22a,
The third expansion chamber 21b and the fourth expansion chamber 21c are connected to the second communication pipe 2.
2b, and furthermore, the second partition wall 2
The tail tube 23 fixed to 0b projects outward from the rear end of the straight tube section 17C. Further, the rear end of the tail tube 23 is slightly bent and substantially horizontal, and the outer peripheral surface is covered with a sound absorbing material (glass wool) 23a.

And the fourth expansion chamber 21 of the left and right straight pipe portions 17c.
A short pipe 24 is connected to the lower surface of the portion c. Each of these short pipes 24 has a connection part 2 with the straight pipe part 17c.
4a is formed into a funnel shape and is bent toward the rear of the vehicle, and the front end of the drain discharge hose 25 is connected to the rear end. This discharge hose 25 is connected to this straight pipe section 1.
Along the lower surface of 7c, that is, above the rear wheel 8, a directional support 26 is attached to the license bracket 1), which extends rearward with a high rear part and is attached to the license bracket 1).
The hose 25 is routed through the inside of the license support part 1)b, and the rear end opening of the hose 25 is connected to the license support part 1).
) is located at the lower end of b. Note that 25a is a throttle member that restricts exhaust gas from being discharged from the exhaust hose 25.

The rear end of the discharge hose 25 is connected to the license support section 1.
)b is fixed to the clamp member 27a, and its substantially central portion is fixed to the clamp member 27b fixed to the support bracket 26a of the directional supporter 26, respectively.

Next, the effects of this embodiment will be explained.

Exhaust gas from the engine unit 14 is expanded in the chamber part 16b (first expansion chamber) of the expansion pipe 16, and the muffler pipe 1
After contracting in the connecting pipe portion 17a of No. 7, the second to fourth expansion chambers 2
13-21C and 1st. It repeatedly expands and contracts in the second communication pipes 22a and 22b, and is discharged outward from the tail pipe 23.

When exhaust gas is discharged in this manner, the exhaust gas becomes muffled and has a low temperature during the expansion and contraction process, and as the temperature decreases, water vapor in the exhaust gas flows into the fourth expansion chamber 21c, which has a particularly low temperature. It condenses inside and becomes drain. This drain is then connected to the discharge hose 2 from the short pipe 24.
5 to the lower end of the license support part 1)b of the license plate 1), and is discharged downward from the lower end.

As described above, in this embodiment, since the exhaust hose 25 is connected to the lower surface of the fourth expansion chamber 21c where water vapor in the exhaust gas is likely to condense, most of the drain generated within the exhaust pipe 15 can be exhausted to the outside. This prevents drainage from accumulating inside and from blowing out all at once, and as a result, the problem of contamination of following vehicles etc. can be solved. Moreover, the drain generated inside the vehicle is discharged downward from the lower end of the license plate 1 located at the rear end of the vehicle.
The drain will not adhere to the rear arm 9 and the like of the motorcycle 1 and the rear seat occupant M2.

Furthermore, since the first half of the drain hose 25 of this embodiment is inclined upward from the horizontal, after the engine is stopped,
The drain that has adhered to the wall of the expansion chamber can be removed using this discharge hose 2.
This will prevent the drain from falling in one place when the drain is stopped.

Furthermore, in this embodiment, the exhaust hose 25 is routed between the rear end of the exhaust pipe 15 and the license plate 1) provided close to this. It is short, and when viewed from the outside,
The front part is located directly below the straight pipe part 17c of the exhaust pipe 15, and the rear part is hidden inside the direction support 26 and the license plate (1), so it is not noticeable. ,
Deterioration of appearance can be suppressed.

Further, in this embodiment, since the throttle member 25a is attached to the rear end of the drain discharge hose 25, exhaust smoke from the hose 25 can be suppressed. Note that even if such a restricting member is installed, the drain can be discharged without any problem due to the internal pressure.

In the above embodiment, the discharge hose 25 is connected to the fourth expansion chamber 2.
Although the exhaust hose of the present invention is connected to the third expansion chamber 21b, the discharge hose of the present invention may be connected to any other position at the rear of the exhaust pipe, for example, to the third expansion chamber 21b. It may be connected to the compartment; in this case, the exhaust hoses from both compartments may be combined and then routed within the license plate.

Further, although the above embodiments were for a two-stroke engine, the present invention can of course also be applied to an exhaust system for a four-stroke engine.

〔Effect of the invention〕

As described above, according to the exhaust system for a motorcycle according to the present invention, the drain discharge hose is connected to the rear lower surface of the exhaust pipe, and the discharge hose is routed inside the license bracket. Since it is opened, it has the effect of preventing not only the following vehicle but also the motorcycle itself from being soiled, and is also less noticeable and has the effect of suppressing deterioration of the appearance.

[Brief explanation of the drawing]

1 to 6 are diagrams for explaining an exhaust system according to an embodiment of the present invention, in which FIG. 1 is a side view of the rear part of the exhaust pipe, FIG. 2 is a cross-sectional side view of the rear part, and FIG. 3 and 4 are a sectional view taken along the line ■-■ in FIG. 1, a sectional view taken along the TV-IV line, FIG. 5 is a front view of the exhaust system of the embodiment, and FIG. FIG. 2 is a side view of the motorcycle. In the figure, 8 is a rear wheel, 14 is an engine unit, 1.
1 is the license bracket, 15 is the exhaust pipe 21c is the 4th
In the expansion chamber (at the rear of the exhaust pipe), 25 is a drain discharge hose. Patent Applicant Yamaha Motor Co., Ltd. Agent Patent Attorney Tsutomu Shimofu Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] (1) An exhaust system for a motorcycle in which an exhaust pipe connected to the engine is extended to the rear of the vehicle through the upper side of the vehicle, and the exhaust pipe discharges exhaust gas from the engine to the rear of the vehicle. One end of a drain discharge hose for discharging the drain in the exhaust pipe is connected to the lower surface of the rear, the drain discharge hose is routed inside the license bracket passing above the rear wheel, and the other end of the drain discharge hose is routed to the inside of the license bracket. An exhaust system for a motorcycle, characterized in that an opening is located at the bottom of the license bracket.