Internal-combustion engines – Two-cycle – Whirl through piston-controlled ports
Patent
1997-07-14
2000-06-27
McMahon, Marguerite
Internal-combustion engines
Two-cycle
Whirl through piston-controlled ports
1235591, F02B 2900
Patent
active
060793783
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a suction device for a supercharged 4-cycle engine having a supercharge mechanism.
BACKGROUND ART
There has been proposed a supercharged 4-cycle engine, for example, such that a connecting rod housing chamber surrounded by a crank chamber, a crank web, and a piston is partitioned by a connecting rod into a suction chamber and a compression chamber so that the air sucked through the rocking of the connecting rod is compressed to be supercharged into the combustion chamber (see Japanese Patent Application Laid-Open No. 6,93869).
A suction device for such a supercharged engine has been known such that a chamber having a comparatively large capacity is communicatively connected to the compression chamber, the chamber and the combustion chamber being communicatively interconnected by a suction passage, with a carburetor disposed in the suction passage. This chamber is to store pressurized air therein thereby to inhibit an air pressure drop during a suction stroke so as to enhance the efficiency of charging. Conventionally, the capacity of the chamber has been set as large as possible, even on the order of, for example, more than 20 times the quantity of engine displacement.
However, when such a supercharged engine is employed in, for example, a small-size vehicle, such as automotive two-wheel vehicle, one problem is that it is difficult to secure necessary space for disposition of such a large-capacity chamber.
Another problem is that, in the case of a supercharged engine of the above mentioned type, if the supercharged pressure is increased when the compression ratio is set at a usual level, there will occur knocking such that the output of the engine does not go up even if the quantity of the mixture is increased.
This invention has been made in view of the foregoing situation of the art and has as its object the provision of a suction device for a supercharged engine which can prevent knocking when the engine is equipped with a supercharge mechanism and can realize a size reduction to enable use in a small type vehicle.
DISCLOSURE OF THE INVENTION
The invention of claim 1 presents a suction device for a supercharged engine wherein intake air pressurized by a supercharge mechanism is supplied to a combustion chamber, characterized in that where the capacity of a suction passage communicatively interconnecting the supercharge mechanism and the combustion chamber is V and displacement is V0, V/V0 is set within the range of from 1 to 20 and in that an intake valve for opening and closing a combustion chamber opening at a downstream end of the suction passage is closed within the range of from 70 to 100 degrees after a bottom dead center.
When the "displacement" of the combustion chamber (V0) is referred to in this specification and the claims, the term "displacement" is used in the normal sense applied in referring to engine capacity or size. That is, the displacement of a single cylinder is the volume displaced by the piston during a complete stroke of operation. Thus, if a cylindrical bore is employed, the displacement is equal to .pi.D.div.4.times.S where D equals the diameter of the cylinder bore and S equals the stroke of the piston.
The invention of claim 2 is characterized in that in the invention of claim 1 the cross-sectional area of the suction passage is generally uniform over the entire length of the passage.
In the invention of claim 2, the expression "the cross-sectional area is generally uniform" means that the passage has no part which positively functions as a storage chamber for pressurized air. The time for closing the intake valve may be fixed within the above angular range, or may be variable within and outside the angular range.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional side view for explaining a suction device for a supercharged 4-cycle engine which represents one embodiment of the invention;
FIG. 2 is a sectional rear view (a section taken on line II--II in FIG. 1) showing a crank shaft portion of the engine represen
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patent: 4932368 (1990-06-01), Abe et al.
patent: 5121733 (1992-06-01), Goto et al.
patent: 5427078 (1995-06-01), Hitomi et al.
patent: 5429100 (1995-07-01), Goto et al.
patent: 5509394 (1996-04-01), Hitomi et al.
Norimatsu Nobuo
Taue Jun
McMahon Marguerite
Yamaha Hatsudoki Kabushiki Kaisha
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