JPH0468193B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a motorcycle.

[Conventional technology]

In a motorcycle equipped with an exhaust pipe that passes below the engine to the rear of the vehicle body and extends upward from below the rear fork arm to the side of the vehicle body and rearward of the vehicle body, the front part of the exhaust pipe is connected to the engine and the rear fork arm. The rear fork arm is located downward, and the rear fork arm has a substantially V-shape when viewed from the side, and the rear fork arm intersects with the rear large diameter portion of the exhaust pipe behind the curved portion of the rear fork arm. is known, for example, as shown in MOTOR CYCLIST, April issue, 1980.

[Problems to be Solved by the Invention] However, in such a structure, the rear large-diameter portion of the exhaust pipe with the largest cross-sectional shape intersects with the rear fork arm, so that the exhaust pipe is There is a problem in that the outer wall surface largely protrudes to the side of the vehicle body, and as a result, the bank angle becomes small.

The present invention has been made in view of the problems of the prior art, and its purpose is to intersect the curved part of the rear fork arm and the small diameter part of the rear part of the exhaust pipe when viewed from the side. The purpose of the present invention is to provide a motorcycle that can secure a large bank angle.

[Means for Solving the Problems] In order to achieve the above object, the motorcycle of the present invention includes a front small diameter part, an expansion part, and a rear small diameter part, which passes below the engine toward the rear of the vehicle body, and has a rear fork arm. In a motorcycle equipped with an exhaust pipe that extends from below to the sides of the vehicle body and to the rear of the vehicle body, the expansion part of the exhaust pipe is located below the engine and the rear fork arm part, and the rear fork arm part is located below the engine and the rear fork arm part. The arm portion is formed into a substantially V-shape, and the curved portion of the rear fork arm portion intersects with the rear small diameter portion of the exhaust pipe.

[Function] When viewed from the side, the curved part of the rear fork arm intersects with the small diameter part of the rear part of the exhaust pipe.
At the intersection, the amount of protrusion of the outer wall surface of the exhaust pipe toward the side of the vehicle body becomes small. Furthermore, since the expansion part of the exhaust pipe is located forward and below the curved part of the F-shaped rear fork arm, the large diameter part of the expansion part is located away from the curved part of the rear fork arm. .

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a side view of a motorcycle 1 used for road racing, Fig. 2 is a plan view of a portion thereof, Fig. 3 is a side view with a part of the engine cut away, and Fig. 4 is a diagram of its power system. be. That is, a separately formed steering shaft tube 3 is attached to a bracket 2a in front of the vehicle body frame 2 by bolts 4, and the steering shaft tube 3 allows a front fork 6 having a front wheel 5 to be turned left and right. It is pivoted. 7 is a steering handle attached to the front fork 6. From the front bracket 2a, there is a main frame member 8 which is assembled by welding a plurality of steel pipes.
extends rearward and downward, and at the rear end there is a rear bracket 2b.
is permanently installed. The rear part of the engine 9 is fixed to the rear bracket 2b, and a rear fork 11 having a rear wheel 10 is supported by a pivot shaft 11a so as to be able to swing vertically. There is a drive chain 12 between
is being passed over. The arm portion of the rear fork 11 is an arm portion 1 that extends linearly from the pivot shaft 11a toward the upper side of the rear wheel shaft 10a of the rear wheel 10.
1b, and a pivot shaft 11a from the rear wheel shaft 10a.
The arm rear part 11c extending downward and the arm curved part 11d connecting these parts form a substantially V-shape in side view, and the lower edge 11e of the arm curved part 11d among the lower edges of the arm. is curved upwards.

14 is an engine cooling water radiator, 15U is an upper exhaust pipe extending from an upper cylinder of the engine 9, which will be described later, and 15L is a lower exhaust pipe extending from a lower cylinder. An arm 16 is rotatably attached to the cross member 8a at the upper part of the main frame member 8, and the free end of the arm 16 is connected and fixed to the rear bracket 2b by a rod 17. The other end is connected.
19 is a fuel tank, and 20 is a passenger seat.

The engine 9 is disposed in a substantially triangular space formed between the lower surface of the main frame member 8, which extends substantially linearly from the steering shaft tube 3 toward the rear bracket 2b with a downward slope toward the rear, and the ground. ing. That is, a crankcase 9b is supported on the rear lower surface of the main frame member 8, and on the front side of the crankcase 9b there is an upper cylinder 9e extending obliquely upward along the main frame member 8, and an approximately horizontal cylinder located below the upper cylinder 9e. A lower cylinder 9f extending in the direction is provided, forming a V-shaped engine. 9d is both cylinders 9e, 9
This shows an air-fuel mixture generating means such as a carburetor or a fuel injection device arranged between f. To explain the engine 9 in more detail, the two cylinders 9e and 9f have substantially the same configuration, and as shown in FIG.
2 and a piston 23 slidably fitted therein, and a combustion chamber 24 is formed in the top surface of the piston 23. 25 is a spark plug. A crankshaft 26 is housed in a crank chamber 27 and connected to the piston 23 via a connecting rod 26a. 28 is a scavenging passage, and 29 is an exhaust passage. Reference numeral 30 denotes an intake passage leading into each crank chamber 27, and two of the intake passages 30 are arranged side by side. Reference numeral 31 denotes a throttle valve provided in the intake passage 30, which is controlled to open and close by the driver. Throttle valve 31 of intake passage 30
A disc valve 32 is provided downstream. That is, the disc valve 32 is disposed with a slight gap between the case of the crank chamber 27 and the cover member 33, and is connected by the valve shaft 34 so as to rotate once for every revolution of the crankshaft 26. Reference numeral 35 indicates two valve ports provided symmetrically on the disk valve 32 with the valve shaft 34 in between. The valve shaft 34 has a bevel gear 37 at the shaft end, and the intermediate gear member 3
8 and meshes with the large reduction gear 39. The large reduction gear 39 is connected to the input shaft 41 of the transmission via a clutch 40 and to the crankshaft 26 via a small reduction gear 42. 43
An output shaft is driven by the input shaft 41 via a group of transmission gears 44, and is the same as the output shaft 9a of the engine, and a sprocket 45 for driving the drive chain 12 is engaged therewith. A cooling water pump 46 circulates cooling water between the cooling jacket 21 and the radiator 14.

The lower exhaust pipe 15L is configured by connecting a small-diameter portion 15La extending rearwardly downward from the lower cylinder 9f and an expanding portion 15Lb extending rearwardly upwardly from here under the crankcase 9b to the rear of the vehicle body. ing. The rear small diameter part from the expansion part 15Lb is
It extends from below the rear fork 11 through the lower edge 11e of the arm curved portion 11d toward the side and rear of the vehicle body and upwardly rearward, intersecting the arm curved portion 11d of the rear fork 11 in side view,
A muffler 15Lc is connected to a rear end that extends further to the side of the vehicle than the rear fork 11.

Next, the operation of this embodiment will be explained. When the crankshaft 26 is cranked and the piston 23 begins its upward stroke, the disk valve 32 rotates and allows the valve port 35 to communicate with the intake passage 30. Thereupon, the air-fuel mixture generated by the air-fuel mixture generating means 9d and metered by the throttle valve 31 is introduced into the crank chamber 27. When the piston 23 moves to the downward stroke, the disk valve 32 blocks the intake passage 30, so the air-fuel mixture introduced into the crank chamber 27 is compressed, and as the piston 23 further descends, the scavenging passage 28 closes to the combustion chamber. When it opens in 24, it flows into the interior at once. Piston 23
starts to rise and reaches the end of the compression stroke, spark plug 2
5, and the resulting high pressure forces the piston 23 downwards with an acceleration.
When the downward stroke reaches the middle stage, the exhaust passage 29 opens and the burnt gas in the combustion chamber 24 is discharged.

The engine output thus obtained is transmitted from the crankshaft 26 to the speed change gear group 44 via the reduction small gear 42 and the large gear 39, and is taken out from the sprocket 45 provided at the end of the output shaft, and then transferred to the drive chain 12. The rear wheels 10 are driven through the rear wheels 10.

The two-stroke engine described above is mounted on the motorcycle 1 with the two cylinders 9e and 9f facing forward, and the disc valve 32 is positioned above the crankshaft of the lower cylinder 9f. Furthermore, the intake passage 30 is oriented in the direction in which the vehicle is traveling, so that it can receive the wind pressure of the traveling wind while the vehicle is running. When the vehicle travels and the rear wheels pass over unevenness on the road surface, the rear wheels 10 move up and down, and the rear fork 11 swings about the pivot shaft 11a. Since this rocking motion is absorbed by the buffer spring 18, no large impact is applied to the vehicle body frame 2.

Note that the rod 17 connected to the arm 16 has a turnbuckle shape, and its overall length can be changed. In other words, loosen the lock nut,
When you turn the rod 17 and extend it, arm 1
6 rotates counterclockwise, the initial position of the rear fork 11 is moved upward, and the vehicle height can be lowered. Conversely, by shortening the rod 17, the vehicle height, that is, the minimum ground clearance, can be adjusted higher, and the vehicle settings can therefore be easily changed according to the weight of the occupant and the size of the unevenness of the road surface.

In the above-mentioned embodiment, the rear fork 11 is formed into a substantially V-shape when viewed from the side, and the rear small diameter portion of the exhaust pipe 15L passes through the vicinity of the lower edge 11e of the arm curved portion 11d and intersects with the lower edge 11e when viewed from the side. At the intersection, the amount of protrusion of the outer wall surface of the exhaust pipe toward the side of the vehicle body becomes small, and the large diameter part of the expansion part 15Lb located forward and lower than the rear small diameter part is located away from the arm curved part 11d of the rear fork 11. Even if the exhaust pipe 15L faces the lower edge 11e, a large bank angle can be ensured, and the rear fork 11 and the exhaust pipe 15L are not interfered with.

Further, since the expansion part 15Lb of the exhaust pipe 15L is located below the engine 9 and the rear fork 11, it is possible to bring the expansion part 15Lb of the exhaust pipe 15L closer to the center of the vehicle body. This makes it possible to secure a large bank angle.

[Effects of the Invention] As explained above, according to the present invention, the expansion part of the exhaust pipe is located below the engine and the rear fork arm, and the rear fork arm is made into a substantially V-shaped shape when viewed from the side. Since the curved part of the exhaust pipe intersects with the rear small diameter part of the exhaust pipe, the amount of protrusion of the outer wall surface of the exhaust pipe toward the side of the vehicle body at the intersection becomes small, thereby ensuring a large bank angle. I can do it. Furthermore, since the expansion part of the exhaust pipe is located forward and below the curved part of the F-shaped rear fork arm, the large diameter part of the expansion part is located away from the curved part of the rear fork arm. The exhaust pipe can be placed without sacrificing engine performance.

[Brief explanation of the drawing]

Fig. 1 is a side view showing a motorcycle according to the present invention, Fig. 2 is a plan view showing a part thereof, Fig. 3 is a side view with a part of the engine cut away, and Fig. 4 is a power system diagram thereof. be. 9...Engine, 9b...Lower cylinder, 11
...Rear fork, 11b...Forearm part, 11c...
...Arm rear part, 11d...Arm curved part, 11e...Lower edge, 15L...Exhaust pipe, 15La...Front small diameter part,
15Lb...Expansion part.

Claims (1)

[Claims] 1 An automatic vehicle equipped with an exhaust pipe consisting of a front small diameter part, an expansion part, and a rear small diameter part, passing below the engine toward the rear of the vehicle, and extending from below the rear fork arm toward the sides of the vehicle and the rear of the vehicle. In a two-wheeled vehicle, the expansion part of the exhaust pipe is located below the engine and the rear fork arm, and the rear fork arm is shaped like a substantially V-shape when viewed from the side, and the curved part of the rear fork arm and the rear small diameter part of the exhaust pipe A motorcycle made by crossing the