JP2554326B2 - Exhaust system for motorcycle - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a motorcycle exhaust system in which an exhaust outlet at the rear end of a silencer is located in front of a rear end portion of a rear arm.

[Conventional technology]

The muffler of the motorcycle is exposed to the side of the vehicle body in the vicinity of the rear arm and is one of the important exterior elements of the motorcycle. Recently, a motorcycle has been developed in which the front-rear length of the silencer is set as short as possible to emphasize the size of the engine and the length of the wheel base.

[Problems to be Solved by the Invention]

However, when the muffler is shortened, the exhaust outlet opening at the rear end of the muffler is located in front of the rear end of the rear arm. The wheel brake mechanism and shock absorber are exposed to the exhaust gas discharged from the exhaust outlet.

Therefore, in order to enhance the value and texture of the motorcycle, even if the rear arm is made of aluminum alloy or the brake mechanism and the shock absorber are plated, these components will be stained black by the soot in the exhaust and the appearance will be impaired. There is a problem that it is said.

The present invention has been made based on such a situation, and it is possible to prevent the vicinity of the rear end of the rear arm from being soiled in black by exhaust gas, and moreover, it is possible to firmly hold the tail pipe connected to the exhaust outlet. An object of the present invention is to obtain an exhaust device for a motorcycle that can prevent the pipe from falling off and the exhaust gas from leaking, and can prevent the tail pipe from being stolen.

[Means for solving the problem]

To achieve the above object, the present invention provides a rear arm having left and right arm portions pivotably supported by a frame; a rear wheel supported between rear end portions of the arm portions; A brake mechanism disposed at the center of rotation of the arm; a shock absorber installed between the rear end of the arm portion and a frame positioned above the arm portion; disposed on the outer side of the rear arm and attached to the rear arm. And a plurality of cylindrical silencers vertically adjacent to each other and extending in the front-rear direction; and the silencer is provided at a rear end thereof from a position adjacent to a side of the rear arm. A cut portion having a cut portion that is cut so as to incline forward as advancing outward in the vehicle width direction, and an exhaust outlet that is opened rearward inside the cut portion are provided, and the cut portion and the exhaust outlet are described above. Together it is positioned in front of wheel brake mechanism and the shock absorber, to the exhaust outlet, assumes an exhaust system for a motorcycle which is connected to tail pipe defining the discharge direction of the exhaust.

The tail pipe is bent inside the cut portion in a circular arc shape in a direction away from the rear arm, and the tail pipe is opened outward or downward of the rear arm, and the opening of the tail pipe is opened. A flat surface including the end is formed parallel to the flat surface including the cut portion of the cut portion, and a bracket extending toward the rear arm is welded to an outer peripheral surface of a portion of the tail pipe that is a bending outer side, and the bracket is welded. The tip of the bolt is fixed to the inner surface of the peripheral wall of the cut portion via a bolt, and the head of the bolt is positioned between the rear arm and the silencer.

[Action]

According to such a configuration, the tail pipe connected to the exhaust outlet is bent in a direction away from the rear arm, so that the exhaust gas discharged from the exhaust outlet does not flow straight rearward from the rear end of the silencer. The exhaust gas is guided by the tail pipe and flows so as to avoid the rear end portion of the rear arm. Therefore, the rear end portion of the rear arm, the brake mechanism, and the shock absorber are not directly exposed to the exhaust gas flow, even though the exhaust outlet is located in front of the rear end portion of the rear arm.

Moreover, since the outer peripheral surface of the tail pipe to which the bracket is welded is located outside the bend of the tail pipe, when compared with the inside of the bend of the tail pipe, from the opening end of the tail pipe to the connection portion with the exhaust outlet. The distance is long enough. Therefore, the bracket can be arranged at a position distant from the exhaust outlet, and the tail pipe can be supported at two positions spaced apart in the axial direction. As a result, the span of the support portion of the tail pipe becomes long, and this tail pipe can be firmly held at the rear end of the muffler.

Further, according to the above configuration, since the bracket extends toward the rear arm, the bolt for fixing the bracket to the silencer just faces the rear arm. In this case, since the muffler is arranged along the rear arm, even if an attempt is made to insert a tool for loosening the bolt between the rear arm and the muffler, the rear arm and the rear wheel interfere with the tool. Insertion is blocked. Therefore, with the silencer installed, the bolt cannot be loosened and the tail pipe can be prevented from being stolen.

Furthermore, since the head of the bolt enters a narrow space between the silencer and the rear arm, the head of the bolt is hard to see from the outside, which is convenient in terms of appearance.

Example of Invention

The present invention will be described below based on an embodiment shown in the drawings.

The frame indicated by reference numeral 1 in FIG. 1 has a steering head pipe 2 at its front end. The steering head pipe 2 has a box-shaped main member 3 extending rearward.
And a seat pillar tube 4 extending downward is connected to a rear end portion of the main member 3. An engine 5 is mounted in a portion surrounded by the main member 3 and the seat pillar tube 4.

The engine 5 of the present embodiment is a V-shaped two-cylinder engine in which a front cylinder 7 and a rear cylinder 8 are arranged in a V shape in a side view on a crankcase 6, and a carburetor 9 is provided between these cylinders 7, 8. Are arranged.

A bracket 10 is provided below the seat pillar tube 4. This bracket 10 has a rear arm 11
Has its front end pivoted through a pivot shaft 12. The rear arm 11 has a pair of left and right arm portions 13 (only one is shown) extending rearward from immediately after the crankcase 6, and the arm portions 13 are painted silver gray. A backstay 14 of the frame 1 is located above the arm portion 13, and a hydraulic shock absorber 15 is installed between the backstay 14 and the rear end portion of the arm portion 13.

Between the rear ends of the arms 13, the rear wheels 17 are
Is supported. A drum brake 18 as a brake mechanism is incorporated in the hub located at the center of rotation of the rear wheel 17. The brake shoe plate 20 that supports the drum 19 of the drum brake 18 and the brake shoe is buffed to enhance the texture.

The cylinders 7 and 8 of the engine 5 have exhaust pipes 21 and 22 respectively.
Is connected. The exhaust pipe 21 of the front cylinder 7 is guided from the front of the crankcase 6 to the rear through the lower right portion. The exhaust pipe 22 of the rear cylinder 8 is led out to the right side of the crankcase 6, bent in a substantially U-shape on the right side of the crankcase 6, and then led to the rear side. And, the rear ends of these exhaust pipes 21 and 22 are
It is connected to two silencers 24 via an exhaust chamber 23.

Each silencer 24 has a cylindrical outer cylinder 25 extending in the front-rear direction along the rear arm 11. The outer cylinder 25 is the rear arm
At the side of the arm portion 13 on the right side of 11, the upper and lower two stages are arranged adjacent to each other. As shown in FIG. 2, the outer cylinder 25 is provided with a cut portion 37 including a diagonally cut cut 26 at its rear end. The cut 26 is inclined forward as it goes outward from the position adjacent to the arm 13 in the vehicle width direction. The cut 26 has an elliptical shape with a large diameter when the motorcycle is viewed from the side. ing.

The outer cylinder 25 of the muffler 24 is formed so that its entire length is as short as possible in accordance with the design requirements of the motorcycle. Therefore, the cut end 26 at the rear end of the outer cylinder 25 is located in front of the rear end of the rear arm 11, the drum brake 18 of the rear wheel 17, and the lower end of the hydraulic shock absorber 15.

As shown in FIG. 2, an end plate 28 is welded to the rear end of the outer cylinder 25. The end plate 28 is located immediately before the cut portion 37, and the end plate 28 cooperates with the peripheral wall 35 of the cut portion 37 to form a hollow portion 29 at the rear end of the silencer 25. Cavity 29
Is open toward the rear of the silencer 24 through the cut 26. The axial length of the peripheral wall 35 of the cut portion 37 is
Due to the relationship of the inclination direction of the cut 26, the portion facing the arm portion 13 is the longest, and it is continuously shortened as going from there to the outer side in the vehicle width direction.

The end plate 28 closes the rear end opening of the outer cylinder 25 and forms an expansion chamber 27 inside the outer cylinder 25. An exhaust lead-out pipe 30 is coaxially arranged in the expansion chamber 27. The exhaust lead-out pipe 30 is for discharging the exhaust gas guided from the exhaust chamber 23 to the expansion chamber 27, and the rear end portion of the exhaust lead-out pipe 30 penetrates the central portion of the end plate 28 to form the cavity. The part 29 is slightly projected. The rear end opening of the exhaust outlet pipe 30 is opened in the cavity 29, and the rear end opening of the exhaust outlet pipe 30 serves as the exhaust outlet 31 of the silencer 24. Therefore, the exhaust outlet 31 is located in front of the drum brake 18 of the rear wheel 17 and the lower end of the hydraulic shock absorber 15.

As shown in FIG. 2 and FIG. 3, the exhaust outlet 31 has
A tail pipe 32 having a diameter smaller than that of the outer cylinder 25 is connected.
The tail pipe 32 has one end 32a press-fitted into the exhaust outlet 31.
And the other end 32b opened in the hollow portion 29. The tail pipe 32 is curved in an arc shape in the hollow portion 29 toward the side away from the arm portion 13, and the opening 3 at the other end 32b of the tail pipe 32 is formed.
3 is directed to the side opposite to the arm portion 13. The opening 33 of the tail pipe 32 is located inside the cut 26 of the outer cylinder 25, and the plane including the opening 33 and the cut
The plane including 26 is parallel to each other.

The surface 32c on the outer side of bending of the tail pipe 32 has a larger radius of curvature than the surface 32d on the inner side of bending, so that the distance from the end plate 28 to the opening edge of the opening 33 is larger than that on the inner side of the bending. It's getting longer. This surface 32c is the cut portion 3
It faces the portion of the peripheral wall 35 of 7 having the longest axial distance. The bracket 34 is welded to the surface 32c. The bracket 34 extends obliquely downward from a substantially central portion between the end plate 28 and the opening portion 33 of the tail pipe 32 toward the arm portion 13, and a tip portion of the bracket 34 has an inner surface of the peripheral wall 35. A tongue piece 34a is formed so as to overlap with. The tongue piece 34a is fixed to the peripheral wall 35 of the outer cylinder 25 by inserting the bolt 36 from the outside of the outer cylinder 25 and tightening the insertion end with the nut 37.

As described above, the bracket 34 is attached to the tail pipe 32.
Since it extends diagonally downward from the head 36a of the bolt 36
Enters the narrow space between the outer cylinder 25 and the arm 13. Therefore, when the muffler 24 is viewed from above, the head portion 36a is hidden by the outer cylinder 25.

According to such a configuration, the exhaust outlet at the rear end of the silencer 24
Since the tail pipe 32 bent toward the opposite side of the rear arm 11 is connected to the rear arm 31, the opening 33 serving as the outlet of the tail pipe 32 is directed toward the opposite side of the rear arm 11 and the opening of the exhaust outlet 31 is formed. The direction is to the side of the motorcycle. Therefore, as shown by the arrow in FIG. 2, the exhaust gas discharged from the exhaust outlet 31 is guided to the tail pipe 32 and discharged to the outside of the rear arm 11, and bypasses around the rear end portion of the rear arm 11. To flow.

Therefore, even though the exhaust outlet 31 of the silencer 24 is located in front of the drum brake 18 and the hydraulic shock absorber 15 at the rear end of the rear arm 11, these components are placed in the exhaust flow. Instead, it is possible to prevent black stains from the soot of the exhaust.

Moreover, according to the above configuration, the outer peripheral surface of the tail pipe 32 to which the bracket 34 is welded is located outside the bend of the tail pipe 32. Exhaust outlet from the opening edge 31
The distance to the connection part with is sufficiently long. For this reason,
The bracket 34 can be arranged without difficulty in a position distant from the exhaust outlet 31, and the tail pipe 32 can be supported by the outer cylinder 25 at two locations spaced apart in the axial direction.

As a result, the tail pipe 32 can be firmly held, the tail pipe 32 does not easily vibrate, and excessive stress does not occur in the portion of the tail pipe 32 press-fitted into the exhaust outlet 31. Therefore, it is possible to reliably prevent the tail pipe 32 from falling off and the exhaust gas from leaking from the connecting portion between the tail pipe 32 and the exhaust outlet 31.

Further, since the bracket 34 extends toward the arm portion 13, the head portion 36a of the bolt 36 for fixing the bracket 34 to the outer cylinder 25 just faces the arm portion 13. In this case, since the outer cylinder 25 is arranged along the arm portion 13, the head portion 36a of the bolt 36 enters a narrow space between the arm portion 13 and the outer cylinder 25, and Even if an attempt is made to insert a tool for loosening the bolt 36 into the outer cylinder 25, the arm portion 13 and the rear wheel 17 interfere with the insertion of the tool. Therefore, with the silencer 24 installed, the bolt 36 cannot be loosened, and theft or mischief of the tail pipe 32 can be prevented.

Further, the head 36a of the bolt 36 is the outer tube 2 of the silencer 24.
Since it is covered by 5, the head portion 36a is hard to be seen from the outside, which is convenient in terms of appearance.

In the above embodiment, the tail pipe is bent toward the outer side of the rear arm, but the present invention is not limited to this, and the tail pipe is bent downward so that the exhaust gas from the exhaust outlet is directed downwards of the silencer. You may make it discharge toward it.

〔The invention's effect〕

According to the invention described in detail above, the exhaust gas discharged from the exhaust outlet of the muffler flows so as to bypass the rear end portion of the rear arm and the brake mechanism and the hydraulic shock absorber in the vicinity thereof, so that the rear end of the rear arm It is possible to prevent the constituent elements near the section from being stained black with exhaust soot, and to maintain a beautiful appearance.

Moreover, since the bracket that supports the tail pipe can be comfortably placed at a position away from the exhaust outlet, the tail pipe can be supported at two axially spaced locations, and the tail pipe is firmly held at the exhaust outlet. can do. Therefore, excessive stress does not occur in the portion of the tail pipe press-fitted into the exhaust outlet, and it is possible to reliably prevent the tail pipe from falling off and the exhaust gas from leaking from the connecting portion between the tail pipe and the exhaust outlet.

Also, the head of the bolt that fixes the bracket enters the narrow space between the arm and the silencer, so even if you try to loosen the bolt with a tool, the arm and the rear wheel become an obstacle. Tool cannot be inserted. Therefore, when the silencer is installed, the bolt cannot be loosened, and the tail pipe can be prevented from being stolen or mischief. Furthermore, there is an advantage that the head of the bolt can be covered with a silencer, which is convenient in terms of appearance.

[Brief description of drawings]

 The drawings show an embodiment of the present invention. Fig. 1 is a side view of a motorcycle, Fig. 2 is a sectional view of a rear end of a silencer, and Fig. 3 is a rear view of the silencer from the rear. It is a figure. 1 ... Frame, 11 ... Rear arm, 13 ... Arm part, 15 ... Shock absorber, 17 ... Rear wheel, 18 ... Brake mechanism (drum brake), 24 ... Silencer, 26 ... Cut, 31 ...... Exhaust outlet, 32 …… Tail pipe, 34 …… Bracket, 36 …… Bolt, 36a …… Head, 37 …… Cut part.

Claims (1)

(57) [Claims] 1. A rear arm having left and right arm portions pivotably supported by a frame; a rear wheel supported between rear end portions of the arm portions; and a rear wheel disposed at a center of rotation of the rear wheel. A brake mechanism; a shock absorber installed between the rear end of the arm and a frame located above the arm; disposed on the outer side of the rear arm and extending in the front-rear direction along the rear arm And a plurality of cylindrical mufflers arranged vertically adjacent to each other; and the muffler advances to the outside in the vehicle width direction from a position adjacent to the side of the rear arm at its rear end. Accordingly, a cut portion having a cut portion that is cut so as to incline forward and an exhaust outlet that is opened rearward inside the cut portion are provided, and the cut portion and the exhaust outlet are provided to the brake mechanism of the rear wheel or Up In a motorcycle exhaust device in which a tail pipe that regulates the exhaust direction of exhaust gas is connected to the exhaust port in front of the shock absorber, the tail pipe is located inside the cut portion in a direction away from the rear arm. The tail pipe is opened toward the outer side or the lower side of the rear arm, and the plane including the open end of the tail pipe is formed parallel to the plane including the cut portion of the cut portion. Also, a bracket extending toward the rear arm is welded to the outer peripheral surface of the portion of the tail pipe that is on the outer side of bending, and the tip of the bracket is fixed to the inner surface of the peripheral wall of the cut portion via a bolt. In addition, the head of the bolt is located between the rear arm and the muffler. Car exhaust system.