JPH0610146Y2 - Multi-cylinder engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a multi-cylinder engine having a plurality of cylinders.

[Prior art]

For example, in a V-type 4-cylinder engine, a group of cylinders is arranged in front of and behind the traveling direction of the vehicle, a carburetor is arranged between the groups of cylinders, and an opening of an exhaust port is The front cylinder group is formed on the front surface, and the rear cylinder group is formed on the rear surface.

In this type of multi-cylinder engine, generally, the exhaust pipe connected to the rear cylinder is linearly extended rearward as it is, but the exhaust pipe connected to the front cylinder passes through the curved portion and then the engine. Since it is guided to the lower side of the main body and is extended rearward from the main body, the shape and length of the exhaust pipe are greatly different between the front and rear cylinders.

Such a difference in the shape and length of the exhaust pipe will appear as a difference in exhaust efficiency and a difference in output characteristics between the front and rear cylinders, and the output valley in a certain rotation speed range in the total output characteristics of the engine. As a result, the drivability is deteriorated.

In addition, the exhaust pipe guided below the engine body may cause a decrease in the minimum ground clearance, and the bank angle may not be large.

Furthermore, in an engine in which a carburetor is arranged between cylinder groups, the arrangement of the carburetor with respect to traveling wind is not uniform, which further promotes the above-mentioned difference in output characteristics.

[Purpose of device]

An object of the present invention is to provide a multi-cylinder engine in which the output characteristics of each cylinder can be made as equal as possible without lowering the minimum ground clearance of the vehicle on which it is mounted.

[Constitution of device]

The multi-cylinder engine according to the present invention is a multi-cylinder engine in which each cylinder has an independent carburetor and exhaust pipe, and when the vehicle is mounted on a vehicle, a horizontal plane whose axis passes through the axis of the crankshaft. Above each other, the cylinders are arranged in the crankcase in a V-shape along the front-rear direction and are offset from each other in the vehicle width direction. Each of the carburetors is extended rearward from the rear surface, and the individual carburetors are arranged in parallel on the front surface of the crankcase above the axial center of the crankshaft and at substantially the same height. ing.

According to the above configuration, the exhaust pipes connected to the respective cylinders can be made to extend rearward substantially linearly in a manner of passing above the crankcase, and their lengths can be easily made the same.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings illustrating one embodiment.

1 and 2 show a multi-cylinder engine according to the present invention.

This engine is a V-type 4-cylinder two-cycle engine for mounting on a motorcycle, and when mounted on the vehicle body, has a V-shape in the front-rear direction above the horizontal plane where each axis passes through the axis of the crankshaft 22. Two cylinders 1 and 2, which are in the shape of each other and are offset from each other with respect to the vehicle width direction, that is, are inclined forward, are arranged in the central portion of the crankcase 3 with respect to the vehicle width direction. At the same time, two cylinders 4 and 5 which are inclined rearward are arranged on both sides of the crankcase 3.

In each of the cylinders 1, 2, 4, and 5, exhaust port openings 6, 7, 8, and 9 are formed on the rear surface, and exhaust pipes 10, 11, and 12 are formed in these openings 6, 7, 8, and 9. , 13 are connected. As is clear from FIG. 2, all of these exhaust pipes 10, 11, 12, and 13 pass above the crankcase 3 and are substantially linearly rearward without lowering the minimum ground clearance of the motorcycle. And have substantially the same length as each other.

The intake ports of each cylinder 1, 2, 4, 5 in this engine are formed in the front part of the crankcase 3, and the openings 14, 15, 16, 17 of these intake ports are opened in the front surface of the crankcase 3. Has been done. Then, the vaporizers 18, 19, 2 are provided in the openings 14, 15, 16, 17, respectively.
0 and 21 are connected.

As is clear from FIG. 2, these vaporizers 18, 1
Reference numerals 9, 20, and 21 are substantially the same as each other in a dead space formed in a portion of the front surface 3a of the crankcase 3 which is located above the axis of the crankshaft 22, that is, in a root portion of the front cylinders 1, 2. They are arranged side by side from the height position.

In the engine configured as described above, each carburetor 18,
The air-fuel mixture generated in 19, 20, and 21 is supplied to the crank chambers of the cylinders 1, 2, 4, and 5 through the respective intake ports. At that time, each vaporizer 18, 19, 20, 21
As described above, since they are arranged in the same direction from substantially the same height position, they receive the traveling wind evenly. Therefore, the vaporizers 18, 1
Each cylinder 1, due to the difference in the arrangement of 9, 20, 21
It is possible to prevent variations in output characteristics between 2, 4 and 5 as much as possible.

The air-fuel mixture supplied to each crank chamber is supplied to each cylinder 1, 2,
It is supplied to the combustion chambers 4, 5 and burned there, and then exhausted to the rear of the vehicle through the exhaust pipes 10, 11, 12, 13. At that time, as described above, each cylinder 1, 2, 4, 5
The exhaust pipes 10, 11, 12, and 13 connected to the cylinders are linearly extended rearward and have substantially the same length, so that the cylinders due to the difference in their shapes and lengths are connected. 1,
It is possible to prevent variations in output characteristics between 2, 4 and 5 as much as possible.

In addition, although the V-type 4-cylinder 2-cycle engine is shown in the above-mentioned embodiment, the present invention can be applied to other V-type multi-cylinder engines, as a matter of course.

[Effect of device]

As described above, in the multi-cylinder engine according to the present invention, the exhaust pipes connected to the respective cylinders can be extended substantially linearly rearward, and the lengths of the exhaust pipes can be easily made the same. Therefore, it is possible to prevent variations in the output characteristics of the cylinders due to differences in the shape and length of the exhaust pipe as much as possible.

Moreover, since the exhaust pipe of each cylinder can be extended rearward so as to pass above the crankcase, the minimum ground clearance of the mounted vehicle can be increased, and for example, a large bank angle can be secured. Therefore, there is no fear of impairing the motion performance of the vehicle.

Further, since the carburetor of each cylinder is disposed in the dead space defined between the front cylinder and the crankcase in the same direction from substantially the same height position, the vehicle to be mounted The space can be effectively used, and variation in output characteristics between the cylinders due to the difference in the arrangement of the carburetor is not caused.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual plan view of a multi-cylinder engine according to the present invention, and FIG. 2 is a conceptual side view of the engine. 1, 2, 4, 5 ... Cylinder, 3 ... Crankcase, 3a ... Front of crankcase, 10, 11, 12, 13 ... Exhaust pipe, 18, 19, 20, 21 ... Vaporizer, 22 ... Crankshaft.

Claims (1)

[Scope of utility model registration request] 1. A multi-cylinder engine in which each cylinder is provided with a carburetor and an exhaust pipe which are independent of each other, and when each cylinder is mounted on a vehicle, the axis of each cylinder is above a horizontal plane passing through the axis of the crankshaft. The respective cylinders are arranged in the crankcase in a manner that they are V-shaped along the front-rear direction and are offset from each other in the vehicle width direction, and the individual exhaust pipes are respectively rearward from the rear surfaces of the respective cylinders. Further, the individual carburetors are arranged in parallel in the front surface of the crankcase above the axis of the crankshaft and from the height positions substantially the same as each other toward the front. A multi-cylinder engine that does.