JPH0479874B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a motorcycle equipped with a horizontally opposed internal combustion engine in which the axis of the cylinder is directed in the longitudinal direction between the front and rear wheels. The purpose is to shorten the distance between the wheels as much as possible.

[Prior art]

A horizontally opposed internal combustion engine has a well-balanced inertia and weight and produces less vibration, so when it is installed in a motorcycle, it is easy to design a motorcycle with less vibration and noise, especially when reciprocating masses such as pistons move in the front-rear direction. If the cylinder axis is arranged in the longitudinal direction of the vehicle, the perceived vibration can be further reduced. However, in this engine, at least two cylinders are arranged in substantially symmetrical positions with the crankcase in between, so the dimensions of the cylinders in the axial direction become large. Therefore, when mounted on a motorcycle with the cylinder axis aligned in the longitudinal direction of the vehicle, the width of the vehicle can be reduced, but at the same time the distance between the front and rear wheels becomes larger.
There is a problem that makes it difficult to downsize the vehicle.

[Summary of the invention]

This invention was made to solve the above-mentioned problems, and focused on the fact that when a horizontally opposed internal combustion engine is mounted on a motorcycle, a rather large dead space is created at the top of the engine, and the rear cylinder is compared to the front cylinder. The main feature is that the gap between the rear end of the rear cylinder and the rear wheel is increased by moving the rear cylinder slightly upward, and the distance between the front and rear wheels is reduced by moving the rear wheel forward.

〔Example〕

The present invention will be explained below with reference to illustrated embodiments.
In the figure, reference numeral 1 denotes a motorcycle, in which a front wheel 4 is supported at the front end of a body frame 2 via a front fork 3, and a rear wheel 6 is supported at the rear via a rear fork 5. A horizontally opposed four-cylinder internal combustion engine 7 is mounted between the front wheels 4 and the rear wheels 6.

As shown in FIG. 2, the engine 7 supports a crankshaft 9 in a crank chamber consisting of a front crank chamber case 8a and a rear crank chamber case 8b, and has a front cylinder 9a and a rear cylinder 9b in the crank cases 8a and 8b, respectively. is provided. The axis C1 of the front cylinder 9a is below the crankshaft 9, and the axis C2 of the rear cylinder 9b is below the crankshaft 9.
They are arranged parallel to each other and offset by a distance S to the upper side, and are oriented in the longitudinal direction of the vehicle. Due to this bias, the gap C between the rear lower part of the rear cylinder 9b and the rear wheel 6 becomes larger than the gap C ₀ when the bias is not made as in the past (indicated by the two-dot chain line). The rear wheel 6 can be brought closer to the engine 7 by the same amount. 10 and 10 are pistons that are slidably fitted into the respective cylinders 9a and 9b, and 11 and 11 are connecting rods that connect each of the pistons 10 and 10 to the crankshaft 9. 12 is a generator arranged on the lower surface of the front cylinder 9a; 13
is a transmission arranged on the lower surface of the rear cylinder 9b.

14 is an exhaust pipe led out from engine 7,
It opens into the atmosphere through an intermediate muffler 15a and a muffler 15b at the rear end. 16 is the front and rear cylinder 9
Fuel tank 1 is connected to the intake pipe extending upward from a and 9b.
It opens into an air cleaner 18 arranged on the lower surface of the air cleaner 7, and carburetors 19, 19 are interposed in the middle thereof. 21 is the body frame 2 diagonally in front of the engine 7.
This is a radiator installed for engine cooling. Although the horizontally opposed internal combustion engine in this embodiment is a four-cylinder engine, the present invention is not limited to this, and it is of course applicable to a two-cylinder engine.

When the engine of this embodiment is operated, the crankshaft 9 rotates with the movement of each piston 10, 10, similar to the conventional engine, and output is output to the rear wheels 6 through the transmission 13. Note that the technique of offsetting the cylinder axis to one side with respect to the crankshaft 9 is a well-known and commonly used technique, and does not cause any particular trouble in the operation of the engine.

〔Effect of the invention〕

As described above, this invention mounts a horizontally opposed internal combustion engine between the front and rear wheels with the axis of the cylinder facing in the longitudinal direction, and arranges the rear lower part of the rear cylinder of the internal combustion engine above the axle of the rear wheel. At the same time, since the axis of the rear cylinder is biased upwards from the axis of the front cylinder, the gap between the rear wheel and the rear lower part of the rear cylinder increases, causing the rear wheel to move forward. It becomes possible to close the gap. Therefore, the length of the vehicle in the longitudinal direction can be shortened. That is, the horizontally opposed internal combustion engine can be mounted between the front and rear wheels of the motorcycle with the axis of the cylinder oriented in the front-rear direction without significantly increasing the distance between the front and rear wheels. Further, since only the rear cylinder is biased upward, the center of gravity of the vehicle does not become so high.

[Brief explanation of drawings]

The drawings show one embodiment of the invention,
FIG. 1 is a side view of the main parts of a motorcycle, and FIG. 2 is a longitudinal sectional view of the main parts of a horizontally opposed internal combustion engine. 7... Horizontally opposed internal combustion engine, 8a... Front crank chamber case, 8b... Rear crank chamber case, 9...
...Crankshaft, 9a...Front cylinder, 9b...
Rear cylinder, C1, C2...Front and rear cylinder 9
Axis center of a, 9b, S... deviation.

Claims (1)

[Scope of Claims] 1. A horizontally opposed internal combustion engine is mounted between the front and rear wheels with the axis of the cylinder oriented in the longitudinal direction, and the rear lower part of the rear cylinder of the internal combustion engine is arranged above the axle of the rear wheel. , a motorcycle in which the axis of the rear cylinder is offset upward from the axis of the front cylinder. 2. The motorcycle according to claim 1, wherein the axes of the front and rear cylinders are arranged above and below the axis of the crankshaft. 3. The motorcycle according to claim 1, wherein the axes of the front and rear cylinders are arranged parallel to each other.