Internal-combustion engines – Two-cycle – Whirl through piston-controlled ports
Patent
1997-03-10
1998-09-22
Okonsky, David A.
Internal-combustion engines
Two-cycle
Whirl through piston-controlled ports
123 73B, F02M 6700, F02M 6910
Patent
active
058099492
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to the field of two-stroke engines with controlled air-blast injection.
More precisely, the present invention relates to the operation and to the control of the air-blast injection of fuel in single-cylinder or multi-cylinder two-stroke engines.
BACKGROUND OF THE INVENTION
A conventional way to control air-blast injection consists in connecting the valves to a camshaft. This purely mechanical solution does not provide much flexibility since each cam imposes a precise motion of a valve and, besides, the camshaft supporting several cams, it is a given general motion that is imposed from the start by all the cams. This technology therefore generates a general control common to all the valves of the camshaft. Adjustment is difficult and a problem on one of the cams and/or of the valves can have repercussions on all the other parts at work.
More flexible control systems are known, which are notably based on pressure variations between different chambers co-operating with the motion of the valve.
French patents FR-2,656,653 and FR-2,656,656 thus describe multi-cylinder two-stroke engines in which the air-blast fuel injection is achieved by means of pressure differences between different chambers. This prior art specifically relates to engines having several cylinders since the pressure differences are generated by the angular offset between the cycles of the different cylinders.
SUMMARY OF THE INVENTION
The object of the present invention is to simplify this technology and above all to allow its application to single-cylinder engines, which the above-cited prior art does not allow.
The present invention can nevertheless apply to multi-cylinder engines but, unlike the prior art, in this case the injection works independently in each cylinder. In other words, according to the present invention, each cylinder works, with regard to its air-blast injection, in an independent and autonomous way, with no particular connections between the cylinders. A multi-cylinder engine according to the invention must therefore be considered as an engine having juxtaposed autonomous cylinders.
Generally speaking, the object of the invention consists in making use of the different pressure variations inherent in the running of a cylinder in order to actuate automatically a device intended for air-blast fuel injection into this cylinder. In other words, this consists, according to the invention, in controlling the opening and the closing of a valve automatically at each engine revolution, at precise and predetermined times, without requiring a power-driven means such as a camshaft.
As a result, the adjustment and the control of the injection according to the invention is individual, at the level of each cylinder, which simplifies the conventional multi-cylinder solution.
The present invention thus relates to a two-stroke engine comprising at least: pump crankcase crossed through by the crankshaft of the engine, the cylinder, at least one valve ensuring an intermittent sealing between the chamber and the capacity, membrane separating two chambers and connected to the rod of the valve.
The engine according to the invention further comprises: cylinder, allowing notably the opening of the valve to be activated as soon as possible when the pressure P.sub.B in the chamber becomes lower than the pressure P.sub.S in said capacity.
Preferably, the capacity opens by its other end into an opening of the pump crankcase, a means for controlling said opening being also provided.
Specifically, the engine according to the invention can also comprise a means intended for sealing intermittently said linking means so as to delay the pressure drop in the linking means, i.e. the opening of the valve.
More precisely, said intermittent sealing means can comprise a flange located in the pump crankcase, linked in rotation to the engine crankshaft and comprising at least a peripheral recess.
According to one of its characteristics, the engine can also comprise control means linked to the closing of th
REFERENCES:
patent: 4619228 (1986-10-01), Liu
patent: 5005537 (1991-04-01), Maissant
patent: 5586523 (1996-12-01), Kawahara et al.
Institut Francais du Pe'trole
Okonsky David A.
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