JPH0377380B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an arrangement of intake passages to each cylinder of a multi-cylinder engine for a motorcycle.

In a motorcycle equipped with a multi-cylinder engine, the intake passage to each cylinder is generally restricted in position by the vehicle body structure and engine structure.

However, since the intake air flowing through this intake passage directly affects the performance of the engine due to the dynamic/static pressure and temperature of the outside air, it is desirable that outside air is introduced into each intake passage under the same conditions.

The present invention has been made with this point in mind, and its purpose is to arrange the intake passages of a multi-cylinder engine so that the conditions of the outside air introduced into each intake passage are the same. The purpose is to improve engine performance.

In order to achieve this object, the present invention is equipped with a multi-cylinder engine having front cylinders and rear cylinders arranged in a V-shape when viewed from the side of the vehicle, and having a crankshaft arranged in the left-right direction of the vehicle. In a motorcycle, a V-shaped space formed between the front and rear cylinders is opened toward the front of the vehicle, and an intake passage is formed on the side of the V-shaped space in the multi-cylinder engine, and the opening of each intake passage is approximately It is characterized by opening toward the direction of travel of the vehicle.

The present invention will be explained below with reference to illustrated embodiments. FIG. 1 shows a motorcycle 1 for competition.

That is, a front fork 4 having a front wheel 3 is provided at the front of the vehicle body frame 2 so as to be able to turn left and right, and a rear arm 6 having a rear wheel 5 is supported at the rear so as to be swingable up and down. Reference numeral 7 indicates a water-cooled two-stroke engine suspended at the lower center of the vehicle body frame 2, and reference numeral 8 indicates a radiator for cooling the engine installed in front of the water-cooled two-stroke engine. 9 is a drive chain extending between the engine 7 and the rear wheels 5, 10 is a fuel tank, and 11 is a seat for a passenger.

The engine 7 has two front and rear cylinders 12, 12 arranged in a V shape, each cylinder 1
2 and 12 are connected to exhaust pipes 14 and 14, respectively. Each exhaust pipe 14, 14 extends rearward passing directly above and below the engine 7, and is provided with an exhaust silencer 14a at its rear end. cylinder 1
2 and 12 have similar configurations, one of them is shown in FIG. 2 as a representative. That is, the cylinder 12 is of a water-cooled type having a cooling water jacket 15, and has a cylindrical hole 16 and a piston 17 slidably inserted into the cylindrical hole 16, and a combustion chamber 18 is formed in the top surface of the piston 17. . 19 is a spark plug.
A crankshaft 21 is housed in a crank chamber 22 and connected to the piston 17 via a connecting rod 23. 24 is a scavenging passage, and 25 is an exhaust passage.

The above configuration is not particularly different from conventionally known two-stroke engines. In the engine of the embodiment, two cylinders having the above configuration are arranged in a forward V-shape and are connected to each other by a large reduction gear 33, which will be described later, and the inside of the crank chamber 22 is communicated between them. The intake passages 26, 26 for each cylinder are juxtaposed adjacent to each other. These intake passages 26, 26
The inlet sides of the intake passages 26, 26 are all directed in substantially the same direction within the V-shaped space formed by the two front and rear cylinders 12, 12, and the openings of the intake passages 26, 26 are opened substantially toward the front in the direction of travel of the vehicle. ing. 27 is a carburetor, and 27a is its piston type throttle valve. A disk valve 28 is provided between the carburetor of the intake passage 26 and the crank chamber 22. That is,
The disc valve 28 is arranged with a slight gap between the case of the crank chamber 22 and the cover member 29, and is connected to the valve shaft 3.
1, they are connected so as to rotate once for every revolution of the crankshaft 21.

28a is attached to the disc valve 28 symmetrically with the valve shaft 31.
There are separate valve ports. The valve shaft 31 has a bevel gear 31a at its shaft end, and meshes with a large reduction gear 33 via an intermediate gear member 32. The valve stem 31 may be arranged so as to extend in a direction perpendicular to the crankshaft 21, as shown by the solid line in FIG. , the disc valve 28 is completely closed to both cylinders 1.
It can also fit between 2 and 12. Reduction large gear 3
3 is connected to an input shaft 35 of the transmission via a clutch 34 and to the crankshaft 21 via a reduction gear 35. 36 is an output shaft driven by the input shaft 35 via a gear group 37, and a sprocket 38 for driving the drive chain 9 is engaged therewith. A cooling water pump 39 circulates cooling water between the cooling jacket 15 and the radiator 8.

Next, the operation of this embodiment will be explained. When the crankshaft 21 is cranked and the piston 17 begins its upward stroke, the disc valve 28 rotates and communicates the intake passage 26 through the valve port 28a. There, the air-fuel mixture generated in the carburetor 27 and metered by the throttle valve 27a is introduced into the crank 22. When the piston 17 moves to the downward stroke, the disc valve 28 blocks the intake passage 26, so the air-fuel mixture introduced into the crank chamber 22 is compressed, and as the piston 17 further descends, the scavenging passage 24 closes to the combustion chamber. When it opens into 18, it flows into the inside at once. When the piston 17 begins to rise and reaches the end of the compression stroke, the ignition plug 19 ignites, and the resulting high pressure causes the piston 17 to be pushed down at an accelerated rate. When the downward stroke reaches the middle stage, the exhaust passage 25 opens and the burnt gas in the combustion chamber 18 is discharged as exhaust gas.

The engine output thus obtained is transmitted from the crankshaft 21 to the speed change gear group 37 via the small reduction gear 35 and the large gear 33, and is taken out from the drive sprocket 38 provided at the end of the output shaft, and then sent to the drive chain. 9 to drive the rear wheels 5.

Since the two-stroke engine described above is mounted on the motorcycle 1 with the two cylinders 12, 12 facing forward in a V-shape, each intake passage 26, 26 is provided in the V-shaped space formed by the cylinders. can be opened so that all of its inlet openings are oriented toward the front in the direction of travel of the vehicle, and while the vehicle is running, it receives wind pressure from the traveling wind, so that outside air can flow into each intake passage 26 under the same conditions. be introduced.

As described above, the present invention provides a motorcycle equipped with a multi-cylinder engine having front cylinders and rear cylinders arranged in a V-shape when viewed from the side of the vehicle, and having a crankshaft arranged in the left-right direction of the vehicle. , a V-shaped space formed between the front and rear cylinders is opened toward the front of the vehicle, and the V-shaped space in the multi-cylinder engine is
The present invention is characterized in that an intake passage is formed on the side of the character-shaped space, and the opening of each intake passage is opened substantially toward the front in the traveling direction of the vehicle.

The intake air that flows through the intake passages to each cylinder of a multi-cylinder engine has a direct effect on the performance of the engine due to the dynamic/static pressure and temperature of the outside air.However, outside air is introduced into each intake passage under the same conditions. This made it possible to improve engine performance.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; Fig. 1 is a side view of a competition motorcycle, Fig. 2 is a partially cutaway side view of the engine, and Fig. 3 is a system diagram showing the power system of the engine. be. 7...Engine, 12...Cylinder, 21...
Crankshaft, 26...Intake passage.

Claims (1)

[Claims] 1. In a motorcycle equipped with a multi-cylinder engine having front cylinders and rear cylinders arranged in a V-shape when viewed from the side of the vehicle, and a crankshaft arranged in the left-right direction of the vehicle, A V-shaped space is opened toward the front of the vehicle, an intake passage is formed on the V-shaped space side of the multi-cylinder engine, and an opening of each intake passage is opened toward the front in the direction of travel of the vehicle. A motorcycle engine characterized by: