JPH03220084A - Exhaust pipe structure of motorcycle - Google Patents

Abstract

PURPOSE:To elongate an exhaust pipe, keeping a car body small-sized, by constituting the front pipe of the exhaust pipe out of the first bent pipe, which is extended to the front lower part from an engine cylinder and extended in the car width direction, and the second bent pipe, which is extended to the opposite side from the upper edge of the first bent pipe, extended downward and turned back upwardly. CONSTITUTION:An exhaust pipe 55 is constituted of a front pipe 56 and a rear pipe 60. The front pipe 56 is constituted of the first bent pipe 56a which extends to the front lower part from the cylinder 28 of an engine 25 and extends in one side direction in the car width direction and the second bent pipe 56b which extends to the other side direction in the car width direction from the upper edge of the first bent pipe 56a and extends downward and is turned back upwardly. With this constitution, arrangement is performed by effectively utilizing the space extended vertically along the front surface side of the engine, and the exhaust pipe can be elongated, keeping the car body in compact form.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an exhaust pipe structure for a motorcycle.

(Prior Art) A motorcycle is equipped with an engine and an exhaust pipe extending from the engine.If the exhaust pipe is made long to a certain extent, the inertia effect of the exhaust gas is improved, and engine performance can be improved. This has been known for a long time.

Particularly, when the motorcycle is a trial vehicle, it is mainly operated at low to medium speeds, and the exhaust flow velocity in the exhaust pipe is slow. Therefore, in order to improve the engine performance described above, it is desirable that the exhaust pipe be made longer.

(Problems to be Solved by the Invention) Incidentally, since a motorcycle has a large number of components arranged in a compact manner, the surplus space is small, and therefore it is not easy to lengthen the exhaust pipe. In particular, due to the functionality of trial vehicles, it is strongly required that the body be made compact and that the components of the body not affect the rider's movements.In this case, it is necessary to make the exhaust pipe longer. has become even more difficult.

(Object of the Invention) This invention was made in view of the above-mentioned circumstances, and an object of the invention is to make the exhaust pipe sufficiently long while keeping the vehicle body compact.

(Structure of the Invention) A feature of the present invention for achieving the above object is that, due to the structure of the motorcycle, there is a relatively large space on the front side of the engine mounted on the motorcycle, and
This was created by focusing on the point that it has little effect on the rider's movements, and the front pipe located on the front side of the engine cylinder is extended from the cylinder forward and downward, and then A first bent tube extends to one side in the width direction and then extends upward, and a first bent tube extends from the upper end of the first bent tube to the other side opposite to the one side, and then extends downward. and a second bending tube that extends upward and is then folded back upwards.

(for production) The effects of the above configuration are as follows.

The front pipe 56 of the exhaust pipe 55 located on the front side of the cylinder 28 of the engine 25 has a first bent pipe 56a and a second bent pipe 5.
6b, and the first bent pipe 56a is connected to the cylinder 2.
8, extends forward and downward, then extends to one side in the vehicle width direction, and then extends upward. Further, the second bending tube 56b extends from the upper end of the first bending tube 56a toward the other side opposite to the one side, then extends downward, and then bends back upward. It is.

That is, the front pipe 56 is provided by making effective use of the entire space that extends vertically along the front side of the engine 25.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

In FIGS. 1 to 6, I is a motorcycle, and 2 is its body frame.

The vehicle body frame 2 has a head vibrator 3 at its front part, and from the head vibrator 3 toward the rear and lower side are left and right main frames 4°4 made of sheet metal, which have an elongated box shape in cross section, and are approximately linear in plan view. The front and rear middle portions of these left and right main frames 4.4 are firmly connected to each other by a main cross vibe 5.

Further, rear arm brackets 7 extend downward from the rear ends of each of the main frames 4, and a rear arm 12 is pivotally supported by a pivot shaft 11 on these left and right rear arm brackets 7.7 so as to be able to swing vertically. .

In addition, below the main frame 4.4, down tubes 13 extend rearward and downward from the front ends of each of the main frames 4.6 The Herad Vibe 3 has a front fork 5 for steering. It is freely supported. A front wheel 16 is supported at the lower end of the front fork 15, and a handle 17 is attached to the upper end of the front fork 15. In the above case, the front fork 15 includes a steering shaft (not shown) rotatably supported in the head vibrator 3, an upper bracket 15a attached to the upper and lower ends of the steering shaft, and a lower It is composed of a bracket 15b and a pair of left and right telescopic fork tubes 15c supported by these brackets 15a and 15b, and the front wheel 16 is supported between the lower ends of the left and right fork tubes 15c as described above. Further, this front wheel 16 is provided with a front fender 16a.

On the other hand, a rear wheel 18 is supported at the swing end of the rear arm 12. Reference numeral 19 denotes a shock absorber, and this shock absorber 19 absorbs the shock transmitted from the rear wheel 18 to the vehicle body frame 2 side via the rear arm 12.

An engine 25 is provided below the left and right main frames 4.4. This engine 25 is a two-stroke single-cylinder engine, and a power transmission device 27 is connected to the rear of the crankcase 26, and a cylinder 28 is provided protruding forward and upward from the upper surface of the crankcase 26. A cylinder head 29 is mounted on the cylinder 28.

The upper end of the cylinder head 29 is screwed to the main cross vibe 5 by a port 30 and supported by the left and right main frames 4.4, and the front end of the crankcase 26 is connected to each down tube by a port 31. 1
Further, the rear end of the power transmission device 27 is supported by the pivot shaft 11, whereby the engine 25 is firmly supported by the vehicle body frame 2.

Further, a drive chain wheel 33 is provided on the power transmission device 27 side, while a driven chain wheel 34 is attached to the rear wheel 18, and a transmission chain 35 is wound around both chain wheels 33 and 34. .

A carburetor 40 and an air cleaner 41 are connected to an intake port formed on the rear surface of the cylinder 28 . Further, a fuel tank 46 is provided for supplying fuel to the carburetor 40. This fuel tank 46 is made of resin and is located near the top of the engine 25 and between the left and right main frames 4.4, thereby concentrating the mass of the vehicle body and lowering the center of gravity. This fuel tank 46 is particularly
As shown in the figure and FIG.
The rear end portion is supported on the main cross vibe 5 by another cushioning material 47'. A cap 48 for opening and closing a fuel inlet is provided on the front upper surface of the fuel tank 46.
A cover unit 49 is provided to cover the entire upper surface of the air cleaner 41 and the fuel tank 46, and rubber is pasted on the top surface of the cover unit 49 to form a sheet 50. In addition, in FIG. 6, 53 is a kick pedal of a kick starter.

The exhaust port formed on the front surface of the cylinder 28 includes:
An exhaust pipe 55 made of sheet metal is connected.

This exhaust pipe 55 is composed of a front pipe 56 that once extends forward from the exhaust port and then goes rearward, and a rear pipe 60 that extends from the end of this front pipe 56 to the rear of the vehicle body. .

The front pipe 56 extends forward and downward from the exhaust port of the cylinder 28, and then extends to the right, which is one side in the vehicle width direction,
Next, a first bent pipe 56a extends upward, and a first bent pipe 56a extends from the upper end of the first bent pipe 56a to the left, which is the other side opposite to the one side, and then extends downward. The second bending pipe 56b extends and is then folded back upward. The upper end of the second bent tube 56b extends rearward, bypassing the side of the down tube 13, and the front end of the rear tube 60 is connected to this.

That is, the front pipe 56 is provided so as to make effective use of the entire surplus space extending vertically along the front side of the engine 25 and to have a sufficiently long pipe length.

On the other hand, the rear pipe 60 has a muffler 57 connected to the front pipe 56, and the muffler 57 is arranged on the left side of the cylinder 28 and the carburetor 40, as shown in FIG. It is arranged in a space created between the main frame 4 and the left side of the crankcase 26. In addition, in this case, as shown in FIG. The rider's leg movements are not obstructed by the muffler 57.

In addition, a connecting pipe 5 extends rearward from the rear end of the muffler 57.
8 extends, and this connecting pipe 58 passes through the space created between the rear arm bracket 7 and the shock absorber 19 on the left side. A silencer 59 is connected to the rear end of this connecting pipe 58.

Thus, when the engine 25 operates, outside air is drawn in through the air cleaner 41, mixed with fuel supplied from the fuel tank 46 in the carburetor 40, and this air-fuel mixture is drawn into the cylinder 28, where it is mixed with fuel supplied from the fuel tank 46. , burned. Then, the combustion gas is exhausted through the exhaust pipe 55, and at this time, the power generated in the engine 25 is transmitted to the rear wheels via the power transmission device 27 and the transmission chain 35.
8, and the motorcycle l can now run.

In FIG. 3, a cable body 63 such as a clutch wire or a wire harness is provided that extends downward from the handle 17 side to the main frame 4. This cable body 63 includes the head vibe 3, the upper bracket 15a, and the lower bracket 15.
b and the left fork tube 15c, and extends below the main frame 4, and is supported by a bracket 64 projecting from the lower surface of the main frame 4 along the way. In this case, the cable body 63 may be passed through a space surrounded by the right fork tube 15c instead of the left fork tube 15c.

According to the above configuration, since the element body 63 is located near the helladvib 3, when the handle 17 is steered, the rotational movement of the element body 63 that attempts to rotate with the handle 17 can be suppressed to a small level. . Therefore, the cables 63 are prevented from interfering with each other, and the bending of the cables 63 is suppressed to a small extent, thereby preventing damage to the cables 63. Furthermore, the cable body 63 includes a helad vibrator 3, a lower bracket 15b,
It is surrounded by i5 and fork tube 15c, and is prevented from wandering left and right.

Further, when the front wheel 16 receives an impact and each fork tube 15c contracts while the motorcycle l is running, the space between the lower bracket 15b and the front fender 16a becomes narrow, and the cable body 63 is It also prevents being pinched.

In FIGS. 1, 3, and 5, a device for cooling the cylinder 28 with water is provided. This device has a radiator 61, the upper part of which is disposed between the left and right main frames 4.4, and the lower part of the radiator 61 is disposed between the lower ends of the down tubes 13.13. Further, an electric motor-driven cooling fan 65 is provided corresponding to the rear surface of the radiator 61 .

The lower end of the injection vibro 8 for injecting cooling water is connected to the upper part of the radiator 61, and the upper end side of the injection vibro 8 extends upward between the front ends of the left and right main frames 4, 4.
A cap 69 is attached to its upper end. Also,
The lower end of the radiator 6I is connected by a feed vibe 72 to a cooling water pump 71 attached to the right end of the crankcase 26, and the cooling water in the radiator 61 cooled by the cooling fan 65 and the running wind is transferred to the cooling water pump 71 attached to the right end of the crankcase 26. Cooling water is sent into the cylinder 28 by a cooling water pump 71 to cool the cylinder 28.

Furthermore, the upper end of the cylinder head 29 returns to the vibration 73.
is connected to the upper part of the radiator 61, and the cooling water after cooling the cylinder 28 is returned to the radiator 61 through the return vibe 73.

In FIG. 7, a relay switch 74, a control unit 75, and a vehicle speed sensor 76 are connected to the motor of the cooling fan 65.
is controlled as follows.

That is, when the vehicle speed is low, such as 20 k+s/h, the cooling fan 65 is rotated in the normal direction, and the cooling air from the cooling fan 65 overcomes the traveling wind and is blown out in the forward direction, as shown by arrow A in the figure. It looks like this. According to this, the hot air after passing through the radiator 61 is transferred to the fuel tank 46.
heating is prevented.

On the other hand, at high speeds when the vehicle speed exceeds 20 km/h,
The cooling fan 65 is rotated in the opposite direction, and the cooling air from the cooling fan 65 is blown out rearward, as shown by arrow B in the figure. In this case, since the amount of running wind increases, the temperature of the air that has passed through the radiator 6I is kept relatively low, thus preventing the air that has passed through the radiator 61 from heating the fuel tank 46. Beverage lock and overheating are prevented from occurring, and engine performance is maintained at a good level.

7 to 9, the cooling fan 65 includes a casing 65a that is circular in front view and is provided on the rear side of the radiator 61, and this casing 65a is screwed to the radiator 61 side by a bracket 65b that extends radially. . Further, an electric motor 65c is attached to the center of the casing 65a by the bracket 65b. A fan blade 65 is attached to the output shaft of this electric motor 65c.
d is attached, and this fan blade 65d is located within the casing 65a.

Protective network 5e that covers the cooling fan 65 from the rear side
is detachably attached to the rear edge of the casing 65a by a tightening string 65f. This protective net 65e is mainly used when maintaining and inspecting the vehicle body, and prevents tools from touching the fan blades 65d.

In addition, 78 in FIG. 3 is a footrest, and 79 is a sheet metal engine guard. The front end of this engine guard 79 is screwed to the lower ends of the left and right down tubes 13 and 13 by bolts 80, and the rear end is secured by a port 81 to the It is screwed to the rear arm bracket 7. The engine 25 and the power transmission device 27 are reliably protected by the engine guard 79. Further, the angle θ between the front end of the engine guard 79 and the lower surface of the front pipe 56 with respect to the horizontal direction is set to be 30° or more. It is being And this allows for the concentration of mass.

(Effects of the Invention) According to the present invention, the front pipe of the exhaust pipe extends from the cylinder toward the front and lower side, then extends to one side in the vehicle width direction, and then extends upward. a bent tube, and a first bent tube extending from the upper end thereof toward the other side opposite to the one side;
Since it is configured with a second bent pipe that extends downward and then is folded back upward, the front pipe makes effective use of the entire space that extends vertically along the front side of the engine. It is provided. Therefore, the exhaust pipe does not protrude significantly from the vehicle body, and the exhaust pipe can be made sufficiently long without affecting the rider's movements.

(Margin below)

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is a front view, Fig. 2 is an overall side view of the motorcycle, Fig. 3 is a partially enlarged view of Fig. 2, Fig. 4 is a plan view, and Fig. 5 is a sectional view taken along the line V-V in FIG. 3, and FIG. 6 is a sectional view taken along the line Vl-Vl in FIG.
Figure 7 is a partially enlarged view of Figure 3, and Figure 8 is a partial enlarged view of Figure 7.
-■ line arrow view, FIG. 9 is a partially enlarged view of FIG. 7. ■...Motorcycle, 25...Engine, 28...Cylinder, 55...Exhaust pipe, 56...Front pipe, 56a...1st
Bent pipe, 56b...second bending pipe, 60...rear pipe. Figure 1 Figure 5 Figure 5

Claims (1)

[Claims] 1. An exhaust pipe for an engine mounted on the vehicle body, which once extends forward from the cylinder of the engine, and then a front pipe that goes rearward, and a rear pipe that extends from the end of this front pipe to the rear of the vehicle body. In a motorcycle exhaust pipe structure consisting of
After the front tube extends forward and downward from the cylinder,
A first bent pipe extending to one side in the vehicle width direction and then extending upward; and a rear end extending from the upper end of the first bent pipe to the other side opposite to the one side. , and a second bent pipe that extends downward and is then folded back upward.