JP2017052344A - Support structure of exhaust pipe in motorcycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a load on a connection part between an exhaust pipe and a muffler in a motorcycle with a unit swing type engine mounted.SOLUTION: In a support structure of an exhaust pipe in a motorcycle with a unit swing type engine 16 mounted, the exhaust pipe 28 connected to the front part of the unit swing type engine 16 is extended rearward, and a muffler 27 is connected to the rear end of the exhaust pipe 28. In the unit swing type engine 16, a bracket 30 is installed for supporting the exhaust pipe 28. The bracket 30 is a separate body from the exhaust pipe 28 and supports a part of the exhaust pipe 28, which is closer to a connection part 32 to the muffler 27 than a connection part 31 to the unit swing type engine 16.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an exhaust pipe support structure for a motorcycle equipped with a unit swing type engine.

A unit swing type is adopted for scooter type vehicles among motorcycles. The unit swing type is a structure in which a front portion of a unit including an engine (referred to as a unit swing type engine) is supported by a body frame and operates like a swing arm.
As this type of technology, for example, in Patent Document 1, in a motorcycle equipped with a unit swing type engine, the front part of the exhaust pipe is supported at one place on the front part of the engine and connected to the rear part of the exhaust pipe. A bracket projecting in the vicinity of the connection portion of the muffler is supported at one position on the rear portion of the engine to support the exhaust device at two points on the front and rear of the engine, and a stay lower in rigidity than the bracket includes the bracket and the bracket. The structure which connects parts other than the said support point of an engine is disclosed.

Japanese Patent Laid-Open No. 5-98959

In a motorcycle equipped with a unit swing engine, vibration is generated in the exhaust pipe connected to the engine due to the influence of the engine and the vehicle body. When vibration is generated in the exhaust pipe, stress tends to concentrate particularly on a portion having a large change in cross-sectional area, such as a connection portion between the exhaust pipe and the muffler, and a load is increased.
In Patent Document 1, the exhaust pipe has a front portion supported by the front portion of the engine. For this reason, there is a wide section where the exhaust pipe is not supported in front of the muffler, and a burden is imposed on a connection portion between the exhaust pipe and the muffler.

  The present invention has been made in view of the above points, and in a motorcycle equipped with a unit swing type engine, the burden on the connection portion between the exhaust pipe and the muffler, which is a portion having a large cross-sectional area change, is reduced. It is an object of the present invention to provide a support structure for an exhaust pipe that can be made to operate.

The exhaust pipe support structure in the motorcycle of the present invention is an exhaust pipe support structure in a motorcycle on which a unit swing type engine is mounted, and an exhaust pipe connected to the front portion of the unit swing type engine extends rearward. A muffler is connected to a rear end of the exhaust pipe, and a bracket that supports the exhaust pipe is attached to the unit swing type engine, and the bracket is separate from the exhaust pipe, Further, a portion closer to the connection portion to the muffler is supported than a connection portion to the unit swing type engine.
Another feature of the exhaust pipe support structure in the motorcycle according to the present invention is that the exhaust pipe connects a pipe connected to a front portion of the unit swing type engine and a pipe connected to the muffler. In the exhaust pipe, the bracket is configured to support between the connection portion between the tubes and the connection portion with the muffler.
Another feature of the exhaust pipe support structure in the motorcycle of the present invention is that the bracket includes a first bracket attached to the unit swing type engine and a second bracket supporting the exhaust pipe. It has the division structure which becomes. For example, the first bracket is an L-shaped bracket having a vertical plate portion attached to a side portion of the unit swing type engine and a horizontal plate portion extending from a lower end of the vertical plate portion, and the second bracket Is a band-type bracket that is fixed to the lateral plate portion of the first bracket and encloses the exhaust pipe. In this case, it is preferable that the first bracket and the second bracket are fixed by bolts.
Another feature of the exhaust pipe support structure in the motorcycle according to the present invention is that it is between the bracket and the unit swing type engine and / or between the bracket and the exhaust pipe. The rubber cushion is interposed between the two.
Another feature of the exhaust pipe support structure in the motorcycle according to the present invention is that the bracket is disposed inside a muffler cover provided on the muffler in a side view of the vehicle body.

  According to the present invention, since the portion closer to the muffler connection portion is supported by the bracket than the connection portion to the unit swing type engine in the exhaust pipe, the exhaust gas that is a portion having a large cross-sectional area change, It is possible to reduce the burden on the connection portion between the pipe and the muffler. For example, if the bracket is integrated with the exhaust pipe by welding or the like, stress may concentrate on the welded part or cracks may occur starting from the welded part, but the bracket is separated from the exhaust pipe. Therefore, it is possible to prevent such a problem from occurring.

1 is a right side view showing a motorcycle according to an embodiment. It is a right view which shows a unit swing type engine. It is a perspective view which shows a part of unit swing type engine. It is a bottom view which shows a part of unit swing type engine. It is a perspective view which shows a bracket. It is a perspective view which shows a 1st bracket and a 2nd bracket. It is a perspective view which shows the modification of a bracket. It is a perspective view which shows the example of the floating support structure of a bracket.

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
In the present embodiment, a scooter type vehicle will be described as the motorcycle 100 as shown in FIG. FIG. 1 is a right side view showing a motorcycle 100 according to the embodiment. In the present application, the front, rear, left, and right directions refer to directions viewed from the driver during boarding, and in FIG. 1, the front is indicated by an arrow Fr and the rear is indicated by an arrow Rr.
A steering head pipe is provided at the front part of the body frame made of steel or aluminum alloy, and the two front forks 1 are supported by the steering head pipe so as to be turnable to the left and right. A handle 2 is fixed to the upper end of the front fork 1. A front wheel 3 is rotatably supported at the lower part of the front fork 1 and a front fender 4 is fixed so as to cover the upper part of the front wheel 3.

The front of the vehicle body is covered from the front by the front cowling 5. Further, a front panel 6 is disposed behind the front cowling 5 so as to face the occupant.
The front leg shield 7 and the rear leg shield 8 are coupled to each other so as to be positioned in front of the occupant's legs below the front cowling 5 and the front panel 6. The front cowling 5, the front panel 6, the front leg shield 7 and the rear leg shield 8 are connected to each other to cover the front of the vehicle body and form an integral appearance.

On the left and right sides near the lower portion of the rear leg shield 8, there are provided low-foot left and right footrest portions 9 extending rearward, and the occupant can sit on the seat 10 with their feet on the footrest portions 9. . A footrest 12 for the tandem seat 11 is provided behind the footrest 9. A center cover 13 is provided between the left and right footrests 9 so as to extend forward and backward while projecting upward, and a floor tunnel portion is formed inside. On the side of the vehicle body, the lower part is covered with the lower side cover 14 and the rear part is covered with the rear side cover 15.
Various vehicle body covers are basically formed of a synthetic resin, and are attached directly to the vehicle body frame or indirectly through a support member such as a bracket.

The motorcycle 100 is equipped with a unit swing type engine 16. The unit swing type engine 16 is shown in FIGS. FIG. 2 is a right side view showing the unit swing type engine 16. FIG. 3 is a perspective view showing a part of the unit swing type engine 16 (illustration of the cylinder assembly 21 and the transmission case 23 is omitted), and FIG. 4 is a bottom view showing a part of the unit swing type engine 16.
The unit swing type engine 16 is configured integrally with an engine 17 and a belt transmission 18 and is supported by a body frame so as to be swingable, and also supports a rear wheel 19 so as to be rotatable, and operates like a swing arm. To do.

  As shown in FIG. 2, the engine 17 is, for example, a water-cooled four-cycle single-cylinder engine, and a cylinder assembly 21 extends from the front portion of the crankcase 20 toward the front and tilts forward in a substantially horizontal direction. The crankshaft supported by the crankcase 20 is rotationally driven by the reciprocating motion of the piston in the cylinder assembly 21. The crankcase 20 is provided with a shaft support 22 through which the unit swing type engine 16 is swingably supported by the vehicle body frame.

Further, a belt transmission 18 is integrally provided from the left side of the crankcase 20 and extends rearward to support the rear wheel 19 in a rotatable manner. A transmission case 23 is integrally formed on the left half of the crankcase 20, and a V-belt type continuously variable transmission mechanism that constitutes the belt transmission 18 is accommodated in a belt chamber formed therein.
In the unit swing type engine 16 configured as described above, the power of the engine 17 is shifted by the belt transmission 18 and transmitted to the rear wheel shaft through the centrifugal clutch mechanism and the speed reduction transmission mechanism to drive the rear wheel 19.

Further, as shown in FIG. 3, on the opposite side of the belt transmission 18 with the rear wheel 19 interposed therebetween, that is, on the right side, a rear arm 24 extends rearward from the crankcase 20 to support the rear wheel 19 rotatably. The rear arm 24 is fixed to the upper boss portion 25 a and the lower boss portion 25 b on the right side surface of the crankcase 20 by bolts 26.
Further, a muffler 27 that swings together with the unit swing type engine 16 is provided on the right side of the rear arm 24. The muffler 27 extends rearward and is arranged so that the tail end faces upward. An exhaust pipe 28 is disposed on the right side of the vehicle body. A front end of the exhaust pipe 28 is connected to the cylinder assembly 21 at the front of the unit swing type engine 16, and a rear end of the exhaust pipe 28 is connected to the muffler 27. Exhaust gas after combustion of the engine 17 is exhausted by the exhaust pipe 28 and the muffler 27.
A rear cushion unit 29 is provided between the vehicle body frame and the transmission case 23 and between the vehicle body frame and the rear arm 24 on both the left and right sides.

Hereinafter, details of the support structure of the exhaust pipe 28 will be described.
As shown in FIG. 2, the exhaust pipe 28 is connected to the lower surface of the cylinder assembly 21 and extends obliquely downward to the rear, and extends rearward in a substantially horizontal direction on the side of the crankcase 20, and then extends obliquely upward to the rear. To the muffler 27. The exhaust pipe 28 is configured to connect a pipe 28 a connected to the cylinder assembly 21 and a pipe 28 b connected to the muffler 27 in order to improve the assemblability, and the connection portion 28 c is positioned on the side of the crankcase 20. To do.

Here, a bracket 30 that supports the exhaust pipe 28 is attached to the unit swing type engine 16. The bracket 30 is a part of the exhaust pipe 28 that is closer to the connection part 32 to the muffler 27 than the connection part 31 to the unit swing type engine 16, specifically, a connection part 28c between the pipes 28a and 28b, It supports between the connection part 32 with the muffler 27.
As shown in FIG. 2, a muffler cover 43 extending forward is provided on the right side of the front end of the muffler 27. When viewed from the side of the vehicle body, the bracket 30 is covered with the muffler cover 43, that is, disposed inside the muffler cover 43. This prevents the bracket 30 from appearing on the appearance and prevents the appearance from deteriorating.

  As shown in FIGS. 5 and 6, the bracket 30 is separate from the unit swing type engine 16 and the exhaust pipe 28, and includes a first bracket 30 a fixed to the unit swing type engine 16 side and the exhaust pipe 28. It has a divided structure including the second bracket 30b to be supported.

  As shown in FIGS. 5 and 6B, the first bracket 30 a is an L-shape having a vertical plate portion 33 and a horizontal plate portion 34 extending in a substantially horizontal direction from the lower end of the vertical plate portion 33. It is a bracket, and the vertical plate portion 33 is fastened and fixed to the side portion of the unit swing type engine 16 by bolts. In the present embodiment, as shown in FIGS. 3 and 4, the first bracket 30a is fastened together by using a bolt 26 that fixes the rear arm 24 to the lower boss portion 25b of the right side surface of the crankcase 20. Fix it. Thereby, the bracket 30 can be assembled without increasing the number of parts.

  As shown in FIGS. 5 and 6A, the second bracket 30b is a band-type bracket that wraps the exhaust pipe 28, and is fastened and fixed to the lateral plate portion 34 of the first bracket 30a by a bolt 36. The second bracket 30 b includes a cylindrical portion 37 having an open portion formed at one place on the outer peripheral surface, and a pair of flat plate portions 38 that are connected to and extend from both edges of the open portion of the cylindrical portion 37. By opening the open portion so that the pair of flat plate portions 38 are separated from each other, the diameter of the cylindrical portion 37 can be increased and the exhaust pipe 28 can be easily inserted. Then, by closing the open portion so that the pair of flat plate portions 38 overlap each other, the cylindrical portion 37 can be reduced in diameter and supported so as to enclose the exhaust pipe 28. The flat plate portion 38 is provided with two bolt holes 39 and nuts 40 corresponding to the respective bolt holes 39. The pair of flat plate portions 38 are overlapped by the two bolts 36 so that the first bracket 30a is overlapped. It can be fastened and fixed to the horizontal plate portion 34.

Thus, the assembly property can be improved by making the bracket 30 into a divided structure. For example, after the first bracket 30a is assembled to the unit swing type engine 16 and the second bracket 30b is assembled to the exhaust pipe 28, it is possible to assemble both the brackets 30a and 30b.
However, the bracket does not have to be divided. For example, if the bracket 130 shown in FIG. 7 is demonstrated with reference to the bracket 30 mentioned above, the shape which integrated the horizontal plate part 34 of the 1st bracket 30a and the flat plate part 38 below the 2nd bracket 30b. It is an example.

Further, a rubber cushion may be interposed between the bracket 30 and the unit swing type engine 16 or between the bracket 30 and the exhaust pipe 28 to support floating.
In the example shown in FIG. 8, a rubber cushion 41 is interposed between the bracket 30 and the unit swing type engine 16. The rubber cushion 41 includes a disc portion located between the longitudinal plate portion 33 and the unit swing type engine 16, a disc portion located between the longitudinal plate portion 33 and the head of the bolt 26, and the circles. And a cylindrical portion through which the bolts 26 are inserted.
A rubber cushion 42 is interposed between the bracket 30 and the exhaust pipe 28. The rubber cushion 42 is a plate-like cushion that is sandwiched between the inner peripheral surface of the cylindrical portion 37 of the second bracket 30 b and the outer peripheral surface of the exhaust pipe 28.
By adopting the floating support structure using the rubber cushion as described above, it is possible to suppress vibrations from being generated in the exhaust pipe 28 due to the influence of the engine and the vehicle body, and to improve the vibration isolation.

  As described above, since the portion closer to the connection portion 32 to the muffler 27 is supported by the bracket 30 than the connection portion 31 to the unit swing type engine 16 in the exhaust pipe 28, the change in the cross-sectional area is large. It is possible to reduce the burden on the connecting portion 32 between the exhaust pipe 28 and the muffler 27, which is a part.

Further, for example, when the bracket is integrated with the exhaust pipe by welding or the like, stress may concentrate on the welded portion or cracks may occur from the welded portion. However, the bracket 30 is separated from the exhaust pipe 28. Therefore, it is possible to prevent such a problem from occurring. Further, since the bracket 30 is separated from the exhaust pipe 28, it is possible to deal with ready-made products as after-parts.
In the present embodiment, the bracket 30 is configured to be attached to the unit swing type engine 16 not by welding but by the bolt 26, so that it can be attached to a ready-made product and the bracket 30 can be easily replaced. Further, when welding is performed, stress may concentrate on the welded portion, but it can be avoided. The same can be said for fixing the first bracket 30a and the second bracket 30b by using bolts 36 instead of welding.

As mentioned above, although this invention was demonstrated with various embodiment, it is not limited only to these embodiment, A change etc. are possible within the scope of the present invention.
For example, in the above embodiment, the example in which the bracket 30 is fixed using the bolt 26 that fixes the rear arm 24 has been described. However, the bracket 30 may be fixed by a dedicated bolt, or may be attached to the unit swing type engine 16. Is not limited.

  16: Unit swing type engine, 17: Engine, 18: Belt transmission, 27: Muffler, 28: Exhaust pipe, 28a, 28b: Pipe, 28c: Connection between pipes, 30: Bracket, 30a: First bracket, 30b: second bracket, 31: connection portion between exhaust pipe and unit swing type engine, 32: connection portion between exhaust pipe and muffler, 33: vertical plate portion, 34: horizontal plate portion, 26, 36: bolt, 37 : Cylindrical portion, 38: flat plate portion, 41, 42: rubber cushion

Claims (7)

An exhaust pipe support structure for a motorcycle equipped with a unit swing type engine,
An exhaust pipe connected to the front of the unit swing type engine extends rearward, and a muffler is connected to the rear end of the exhaust pipe.
A bracket that supports the exhaust pipe is attached to the unit swing type engine,
The bracket is separate from the exhaust pipe, and supports a portion of the exhaust pipe that is closer to the connection portion with the muffler than a connection portion with the unit swing type engine. Support structure for exhaust pipes in motorcycles. The exhaust pipe is configured to connect a pipe connected to a front portion of the unit swing type engine and a pipe connected to the muffler,
2. The exhaust pipe support structure according to claim 1, wherein the bracket supports a portion of the exhaust pipe between a connection portion between the pipes and a connection portion with the muffler.   3. The exhaust in a motorcycle according to claim 1, wherein the bracket has a divided structure including a first bracket attached to the unit swing type engine and a second bracket that supports the exhaust pipe. 4. Tube support structure. The first bracket is an L-shaped bracket having a vertical plate portion attached to a side portion of the unit swing type engine and a horizontal plate portion extending from a lower end of the vertical plate portion,
The exhaust pipe support structure for a motorcycle according to claim 3, wherein the second bracket is a band-type bracket that is fixed to the lateral plate portion of the first bracket and encloses the exhaust pipe.   The exhaust pipe support structure for a motorcycle according to claim 3 or 4, wherein the first bracket and the second bracket are fixed by bolts.   6. A rubber cushion is interposed between the bracket and the unit swing type engine and / or between the bracket and the exhaust pipe, respectively. The exhaust pipe support structure for a motorcycle according to the item.   The exhaust pipe support structure for a motorcycle according to any one of claims 1 to 6, wherein the bracket is arranged inside a muffler cover provided on the muffler when the vehicle body is viewed from the side.

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