JPH0379234B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motorcycle equipped with a horizontally opposed or V-shaped multi-cylinder engine with several cylinders arranged in the front and rear directions, and its purpose is to improve the efficiency of the engine. A large intake box that reduces intake noise can be installed without making any major changes to the body structure of the motorcycle, and furthermore, when the intake box is installed below the fuel tank, the intake box and the engine are extremely close to each other. To solve the problem that the length of the intake passage connecting the intake box and the combustion chamber of the engine cannot be made sufficiently long due to this. In other words, large-sized motorcycles equipped with V-type engines or horizontally opposed engines can be constructed without making any major changes to the body structure, and without reducing the intake air filling efficiency due to shortened intake passages. The purpose is to install an intake box.

Recently, in large motorcycles, it has become necessary to provide an intake box as large as possible in the intake passage in order to reduce noise. However, there are many difficulties in installing a large intake box on a motorcycle without damaging its appearance, and it takes a long time to develop it.

This invention focuses on the fact that the above-described horizontally opposed motorcycles with cylinders arranged in a V-shape have a relatively large space between the engine and the fuel tank above the engine. one on each side of the left and right sides, and the intake box and the front and rear cylinders are connected by a relatively long intake pipe, and this intake pipe is surrounded by the bottom wall of the fuel tank, the intake box, and the engine. It is distinctive in that it is placed in a closed space.

The present invention will now be described with reference to the illustrated embodiments. In the figure, reference numeral 1 denotes a motorcycle, which has a body frame 2 made of steel pipes welded together. The front end of the body frame 2 has a front wheel 3 pivotally supported. Supports Folk 4 freely,
At the rear end, a rear arm 5 that supports the rear wheel 4 is attached to a pivot 6.
It is pivoted so that it can swing vertically. Reference numeral 7 denotes a buffer spring bridged between the vehicle body frame 2 and the rear arm 5. A fuel tank 8 and a passenger seat 9 are supported on the upper side of the vehicle body frame 2.
An engine 10 is suspended below the engine.

The engine 10 is a horizontally opposed four-cylinder engine that includes two front cylinders 12 extending forward from a crank chamber 11 and two rear cylinders 13 extending rearward. An exhaust pipe 15 connects the exhaust muffler 14 attached to the rear of the exhaust pipe 2.

On the side lower surface of the fuel tank 8, intake boxes 16 are provided, one each on the left and right sides, extending in the front-rear direction from above the front cylinder 12 to above the rear cylinder 13.
The ends of intake pipes 17, which extend upward from the front and rear cylinders 12 and 13, bend toward the side of the engine, and extend in a substantially horizontal direction enter the intake box 16, and open facing each other. are doing. Reference numeral 18 denotes a carburetor provided in the middle of each intake pipe 17, and the height dimension of the intake box 16 is set to be approximately the same as the height dimension of the carburetor 18. Reference numeral 19 denotes an atmospheric pipe that opens a portion of the intake box 16 between the intake pipes 17 to the atmosphere. 21 is atmospheric tube 1
This is an air cleaner box provided in the middle of the air cleaner box 9, and has a filter paper 22 inside. The longitudinal and lateral dimensions of the two intake boxes 16 are approximately the same as the dimensions of the fuel tank.

23 is a drive chain extending between the engine 10 and the rear wheels 4, and 24 is a radiator for cooling the engine.

In the above embodiment, when the engine 10 starts,
The air filtered by the air cleaner box 21 is sent to the intake box 1.
The fuel is introduced into the cylinders 6, where it expands to become a stable airflow, and fuel is added to it by the front and rear carburetors 18, 18 to form an air-fuel mixture, which is sucked into the cylinders 12, 13 separately. Naturally, the intake box 16 also functions as an intake noise muffling box that muffles intake noise generated within the engine 10.

As described above, this invention is equipped with an engine having a fuel tank provided on the front upper surface of the vehicle body frame, and having at least two cylinders with a crank chamber sandwiched between the fuel tank and the cylinders at the front and rear in the direction of travel of the vehicle. death,
An intake box and an air cleaner are provided on each side of the left and right sides, extending in the front-rear direction from above the front cylinder to above the rear cylinder, on the lower side of the fuel tank, and a relatively long intake air is provided between the intake box and the front and rear cylinders. This intake system is connected by a pipe, and this intake pipe is placed in a space surrounded by the bottom wall of the fuel tank, the intake box, and the engine, so it can occupy a relatively wide space between the engine and the fuel tank. You can use this to install a large intake box. In addition, since a relatively large space is left between the left and right intake boxes above the engine, the intake pipe can be connected by bypassing it to the extent necessary, and the length of the intake pipe can be made sufficiently long to prevent airflow turbulence. It is possible to suppress this and maintain high filling efficiency. Further, even if the intake pipe is bent, the appearance will not be spoiled if it is hidden by the intake boxes 16 on both sides. Since the intake box 16 utilizes the space above the engine,
This has the advantage of allowing a large intake box to be installed without significantly changing the structure of the vehicle body frame.

Note that, as in the embodiment, if the intake box 16 and the air cleaner box 21 have substantially the same height dimension and are arranged inside and outside one on top of the other, the appearance of the vehicle will not be impaired.
A large air cleaner box can be installed.

[Brief explanation of drawings]

The drawings show one embodiment of the invention,
FIG. 1 is a partially cutaway side view of the motorcycle, FIG. 2 is a partially cutaway plan view of its essential parts, and FIG. 3 is a front view thereof. 2...Vehicle frame, 8...Fuel tank, 10...Engine, 16...Intake box.

Claims (1)

[Scope of Claims] 1. A fuel tank is provided on the front upper surface of the vehicle body frame, and an engine having at least one cylinder at the front and rear in the direction of travel of the vehicle is mounted on the lower surface of the fuel tank with a crank chamber in between, and the fuel tank is mounted on the lower surface of the fuel tank. An intake box and an air cleaner are provided on the lower side of the tank, extending in the longitudinal direction from above the front cylinder to above the rear cylinder, one each on the left and right sides, and a relatively long intake pipe is provided between the intake box and the front and rear cylinders. An intake system for a motorcycle, characterized in that the intake pipes are connected to each other, and the intake pipe is arranged in a space surrounded by a bottom wall of a fuel tank, the intake box, and the engine. 2. An intake system for a motorcycle according to claim 1, wherein the engine is of a horizontally opposed type. 3. An intake system for a motorcycle according to claim 1, wherein the engine is a V-type engine. 4. The intake system for a motorcycle according to claim 1, wherein at least a portion of the intake pipe is connected via a path that deviates from the shortest straight line between the connecting portion to the engine and the intake box. 5. The intake system for a motorcycle according to claim 1, wherein the intake pipe extends in the left-right direction of the vehicle between the engine and the intake box.