US2177020A - Charging of explosion engines - Google Patents

Description

Fig 3 Oct. 24, 1939. o. FUSCALDO CHARGING OF EXPLOSION ENGINES Filed April 22, 1958 (Ja my Fmdw WWW KM PW Patented Oct. 24, 1939.

UNITED STATES PATENT OFFICE Application April 22, 1938, Serial No. 203,482 In Italy April 26, 1937 6 Claims.

This invention relates to the charging of explosion engines. :The general object of the invention is to afford an improved fuel injection method for overfed two stroke explosion engines,

and as well a construction of engine to perform said method.

It is known that in a two stroke explosion engine the exhaust may take place through ports which are controlled by the edge of the piston, while the scavenging and the feeding may take place through other ports which are controlled by a sliding valve, so that the engine could be overfed by stopping the feed (which is carried out under a certain pressure) some time after the shutting off of the exhaust has taken place.

The method according to the present invention is characterized by the feature that the air inlet valve is opened towards the end of the exhausting period and continues to remain opened after the shutting of the outlet, while the fuel injector opens and remains open for a part of the opening period of the valve, the exhaust gases effecting an advantageous warming of the.

parts through which the air and the fuel flow in, so as to prepare optimum conditions for the vaporization of the fuel during the supply.

The engine carrying out the method heretofore specified, is characterized by the feature that the inlet port for the air, and for the combustible mixture, is arranged in a position so as to be uncovered by the piston before the exhaust or discharge port is uncovered. The mixing chamber or duct leading to the first of said ports, therefore, communicates with the bore of the cylinder, while into the rnixing chamber opens the air inlet valve and the fuel injector, which, have an interdependent drive, so that the' injector remains open during a part of the opening of the valve.

In a preferred embodiment, it is this air valve which, lifting, causes the opening of the fuel injector at the proper moment.

The invention will now be explained with ref crence to the annexed drawing, given only as an illustrative example and not to limit the breadth of the invention.

Fig. 1 is an axial section of an engine cylinder according to the invention.

Fig. 2 is an angular diagram showing the action.

Fig. 3 is the working diagram of the air valve and of the injector.

Fig. 4 in axial section shows details of the air valve and fuel injector.

In the drawing: l is the cylinder, 2 the piston, 3 the connecting rod, 4 the crank shaft. Arriving at the lower end of its stroke, the piston uncovers, as usual, the exhaust slits or ports 5, and the exhaust gases discharge into the atmosphere through the conduit 6.

opening diagram of said two valves.

The air feed is atmospheric air delivered by a compressor under constant pressure; said air arrives from the conduit 1, precautionarily cooled, and is allowed to enter into the cylinder by and during the opening of the valve 8, which remains open during a period in which the piston leaves the conduit 9 uncovered; the valve 8 is lifted by a cam ID with the aid of an intermediate plunger II and returned to its seat by the spring I2.

The injector is placed above the valve; it consists of a valve 13 which is pressed by the spring I4 against its seat in the body IS. The rod of said little valve slides with its upper end in the guide l6, while, at its lower end. it projects, with clearance or loose play I1, into the conduit 9, up to a distance s from the valve 8, which distance corresponds to a length some decimillimetres less than the total effective lift of the valve itself. The fuel enters into the injector through the conduit 18, coming from a pump or tank, and at a pressure which is some atmospheres higher than that of the air feed, said fuel filling constantly the body l5 so as to be ready to escape with every opening of the little valve l3. The injection of the fuel, consequently, takes place during the last part of the lift of the air valve 8, that is, when the latter strikes against the rod of the valve I3; thus, there will be had first a supply of pure air (which, partly, performs a scavenging, that is, for the time period in which also the exhaust is opened), then an overfeed of mixture which is formed in the conduit 9, and further again an overfeed of pure air, both these overfeeds taking place after exhaust is closed.

This is clearly'seen in Fig. 3 which (on a larger scale than the Figures 1 and 2) represents the The air valve 8 opens for a height S, according to the curve X during the time period EI, and during the last tract of lift, marked s, said valve opens the little valve l3 for the time period GH.

The sequence and interdependence of the various working phases of the engine can easily be followed by examining what is shown by the diagram Figure 2. Assuming the engine turns in the direction of the arrow, starting from the upper dead point A, the following positions appear:

Position B.The edge of the piston uncovers the feed conduit 9, but the valve 8 is shut, and

. there occurs merely the filling of the said conduit with a small part of the warm combustion products which expand in the cylinder.

Position C.-Opening of the exhaust ports 5 by the descent of the piston.

Position D.--Lower dead point.

Angle (SDI-Commencement of exhaust.

Position E.-Opening of the feed valve 8; as the exhaust is still opened, there will be had a short period of scavenging with pure air up to the position F.

Position F.-Shutting of the exhaust by the rise of the piston and followed by the beginning of the overfeed.

Angle EF.-Duration of the scavenging.

Position G.Opening of the little fuel injection valve. I

Position H.Shutting of the little fuel injection valve.

Angle GH.Duration of the'fuel injection.

Position I.Simultaneous shutting of the feed valve 8 and of the conduit 9 by the rise of the piston, that is to say, termination of the overfeed and beginning of the compression of the part of the piston, to be continued up to the moment of the ignition in the neighbourhood of the upper dead point A! The ignition is caused by any common means, as the spark plug 20.

From the actions shown by the diagram of Fig. 2 it results that during the angle BE the conduit 9 is filled with burnt gases which, especially during the angle BC, have elevated temperature and pressure. During the angle BC, there will consequently occur a small supplementary expansion of the gas contained in the cylinder, which is prejudicial to 'thermic efficiency; but the slight loss of energy which results therefrom is practically compensated through the warming of the walls of the conduit 9, of the valves 8 and I3, and of the air and the fuel which are behind same; a warming which promotes the best conditions for the vaporization of the fuel ouring the supply. Actually, the atomized fuel comes hot out from the injector and strikes the hot valve 8; then in contact with same, the fuel begins to. vaporize while it mixes with the likewise hot air; during the mixing it comes then in contact with the still warm walls of the conduit 9.

A further mixing and vaporization will be caused by an effective vortex action in the cylinder and from the increase of temperature owing to the compression; the agitation may be regulated, among other means, by a deflector 2| arranged on the top of the piston in a known manner.

The atomizing of the fuel and the mixing of same with the air, should be thoroughly promoted from the beginning, and this also serves to facilitate the starting of the engine when cold. Fig. 4 shows, on an enlarged scale, another illustrative example of the two valves by which said purpose may be attained. The lower rod 22 of the injection valve I3 and the head of the air valve 8 (shown both completely opened) are in this cas'e each shaped so as to form a toroidal concave surface; the fuel which comes out from the interior of the injector follows this surface and leaves in an atomized state at the edge of the valve 8, having the form of a plane disk 23; at this moment, the fuel is met, obliquely from the conical disc 24, by air escaping from beneath the valve 8, and in the encounter there are formed vortices which provoke optimum mixing, independently of the vaporizing effect of the tempera- I tures as already mentioned.

We may now examine the action of the feeding device in the case of variable ranges of engine speed.

Since with all ranges the ratio of the apertures S and s" of the air valve 8 and the fuel valve I 3 is constant, it follows that variations of ranges are obtainable with a constant injection of the mixture, but with varying of the air and fuel pressures as to their absolute value, while maintaining a constant ratio between each other. This can be easily obtained by throttling the suction both of the air compressor and the'fuel pump, in unison in any well known manner. In any case, in fact, the variation of the air feed, actually, corresponds to a proportional variation of the fuel supply, and the injection of the mixture remains'constant.

It is understood that in practice the details of execution of the invention may vary without, therefore, a departure from the principles of the invention and, thus, from the scope of the patent.

What I claim and desire to secure by United States Letters Patent is:

1. Charging means for an overfedexplosion air to the chamber, a fuel valve admitting liquid fuel with forced flow to the chamber under pressure higher than the air pressure, and valve mechanism timed with the piston movements and coordinating the air and fuel valves, whereby (a) theair valve is opened shortly before the piston closes the exhaust port thus expediting scavenging, and remains open substantially until the inlet port is closedby the piston, while (27) the fuel valve is opened only after the piston closes the exhaust port, and while the air valve and inlet port are both open, and remains open for only a predetermined portion of the period during which the air valve and inlet port both remain open.

2. Engine charging means as in claim 1 and wherein the air and fuel valves are separately constructed and movable but actuated from the same timing means or cam to open in succession and closein succession.

3. Engine charging means as in claim 1 and wherein the air and fuel valves are normally spaced or disengaged but so located that the air valve as it opens closes the space and thereupon presses and opens the fuel valve, and vice versa, whereby the fuel valve remains open for only a fraction of the open period of the air valve.

4. Engine charging means as in claim 1 and wherein the ports are so located that on the feed stroke the exhaust port closes very quickly after a brief scavenging, while thereafter the inlet port remains open for a relatively long period for overfeed of air with fuel.

5. Engine charging means as in claim 1 and

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