US1821817A - Method of injection of fuel for internal combustion engines - Google Patents

Description

F. RocHEFoR'r METHOD OF INJECTION OF FUEL FOR INTERNAL COllBl ISTION ENGINES Sept. 1

Filed 27. 1927 Patented Sept. 1 1 9 3 1 FRANQOIS ROCHEFORT, OF PARIS, FRANCE INIIEI'JPHOD F INJECTION OF FUEL FQR INTERNAL COMBUSTION ENGIN'ES Application filed May 27, 1927, Serial No. 194,768, and in Trance June 3, 1926.

The present invention relates to the direct supply of fuel to internal combustion en gines in general, and more particularly to engines in which the opening of the atomizer 5 or injection valve is efiected by the fuel itself, forced under pressure by the feed pump or distributer.

) Numerous arrangements are already known for injecting fuel by utilizing compressed air alone as the mechanical agent for atomizing and diffusing the liquid fuel. Arrangements are also knownin which the fuel is broken up or atomized by compressed air or gas within the injector and during the period of injection and diffusion in the interior of the engine cylinder.

In order to retain the advantages resulting from injection by ineans of compressed air or compressed gas, whilst avoiding the use of an auxiliary compressor, which the case of light, high-speed and low-power engines, may constitute a complication and a source of trouble b reason of the delicacy of working of this ind of apparatus, it has been proposed to provide a small chamber for storing up hot air and gases drawn off from the working cylinder during the preceding compression and combustion strokes or phases; these gases afterwards serve for i atomizing and diffusing the fuel at the molment of injection, by projection of the fuel into the working cylinder at the moment of the opening of the injection valve.

But these arrangements involve numerous inconveniences 1. The air and the gas are drawn or tapped off from the Working cylinder by means of a poppet valve or an automatic non-return valve, which cannot ensure accuracy as regards its opening and closing.

. 2. The drawing off of the burning gases from the cylider involves a lessening of the useful driving force, which is in general a greater drawbackto efficiency than would be the use of an auxiliary compressor, considering the enormous fall of temperature suffered by these gases during the time of their storage in the chamber.

3. These gases, being already burnt, have thus become inert and their introduction into the working cylinder during the injection prevents a homogeneous mixture bemg obtained and affects the rapidity of combus- 4. It is impossible to avoid the carry-over of residues of combustion into the chamber by these burnt gases; the result is that in the latter there are formed carbon deposits which prevent the valves or injection needles being kept tight, and in generahrapidly foul the pipes through which the fluid or the two I place in a form too massive to permit the employment of high working speeds of the engines, and vaporized liquid fuel is found in the exhaust gases; this fuel has therefore been evacuated without having been able to burn inside the cylinder during the insufficient time of the combustion period- -The present invention has for object to remedy these drawbacks and to improve considerably the results obtained by compressed- ,air or compressed-gas injection, in order to permit also the reasoned use of high tension electrical ignition, exactly as for a mixture of air and petroleum spirit, but while utilizing heavy oils, mineral or vegetable, as fuel; this electrical ignition constitutes in effect an essential condition-for obtaining high speeds of rotation and wide limits of working, which ensure the flexibility in working'of the petroleum spirit engine.

. In conformity with the mvention, there is provided ":(fllllllllfll' communicating with the working cylinder by nozzles or twyers controlled by a valve, serving at the same time for the injection of the liquid fuel, and operated by the liquid fuel delivered under pressure in such a way that the latter, already squeezed or reduced to a film and atomized at the time of its admission by the,

injection valve, is not, towards the end of j the period of compression in the cylinder, by a part of the carburcttcd mixture compressed in the cylinder and flowing through v I these nozzles or twyers, and is carried along into the chamber, passing through the injection valve, which latter isclosed from just before the point of ignition until the'commencement of the following compression stroke, when the mixture, vaporized in the chamber, returns by the twyers into the working cylinder, by reason of the differenceof 1pressure between the chamber and the wor ing cylinder, before being compressed and ignited, whilst a part of the resh carburetted mixture is directed into the chamber at the end of period.

The principal agent for diffusing the fuel in the working cylinder is thus formed by a part of the carburetted mixture, drawn off this compression from the working cylinder at the end of the liquid fuel, distributed gradually during thecharging period, is reduced toa film and atomized mechanically by the valve, whilst the hot carburetted mixture coming from the working cylinder ensures the diflusion of this fuel in the mixture chamber or capacity. The delivery of fuel by the distributor ceases *just before the mechanically operated closrangement according to the invention in its ing of the injection valve. The fuel is sub- 1 jected to a vaporization as complete as possible in the capacity serving as mixture;

chamber, which is maintained. in any suitable manner at a temperature favourable to this vaporization, but lower than the ignition temperature of the gaseous mixture compressed in this chamber. On the other hand the communication between the chamber and the engine cylinder being suppressed by the positive closing of the injection valve just before ignition in the cylinder, no burning gas can penetrate into this chamber; vaporization takes place rapidly during the whole time that this chamber remains closed.

The invention is applicable both to fourstroke engines and 'to two-stroke engines; the annexed drawing represents by way of example, in axial vertical section, the arapplic'ation to a two-stroke engine.

Above theworking cylinder a there is provided acha'mber b communicating with the interior of the cylinder by means of nozzles or twyers 0 arranged in suitable number and in a circle around the axis of the fuel-injection v valve. This valve is composedof a'flat body d, which is designed to recall spring e bear upon a flat seating 12 formed in the wall of the chamber 6 and which is integral with a cylindrical portion al in the shape of a piston, located in a cylindrical bore 6 formed in the thickness of the wall of the chamber 6. The external diameter of this piston is slightly less than the internal diam- .sure by the distributor (not shown), which is connected with a passage 12 formed in the thickness of the wall of the chamber 2) and extending below the piston d to the bottom of the cylindrical bore 12 serving as housing for the latter. Under the pressure of this fuel, delivered at the correct moment and for a suitable duration by the injection pump, the piston (Z is lifted, carrying with it the valve (1 which is slightly separated from the seat 6 the liquid fuel passes through the very small but exactly calibrated annular clearance formed between the cylindrical piston (l and its housing b and arrives in the form of a thin film between the valve (l and its fiat seating 12 The height of lift of the valve cl is limited by an. abutment rod 6, arranged and guided vertically in the upper part of the chamber .12, in a plug f screwed into the latter; this rod 6 carries-a ball e which comes-into engagement with one of the extremities of a rocking lever g, pivoted at g and connected at g to the operating mechanism (not shown) for closing the valve (Z. The rod e is subjected to the action of a coiled spring a which surrounds it and tends constantly to maintain the lower extremity of the rod (1 separated from the ribs at the upper part of the valve (Z;the fuel, delivered under pressure by the distributor, need not therefore,

in order to lift the valve (1 from its seat If, ever lift the rod 6, but has solely to overcome the inertia of the valve (Z (P, which is very slight by reason of the fact that the piston d and the valve (Z are hollow. A cap 6 screwed upon the central part of the plug f, around the ball abutment c limits the lift of the rod 6 under the action of its In the mechanism effecting the closing of the valve, there is interposed a spring or other elastic device (not shown), in such away as to prevent damage to the parts when the rod 6, under the action of'the rocking lever 9, brings the valve (I back upon its seat 6 thereby cutting off the admission of liquid fuel.

For the explanation of the working of i this arrangement, it. will first be supposed "that the engine is running normally and that the chamber 5 is. filled with a carburetted mixture which has been supplied thereinto at the end of a preceding compression stroke, as will be hereafter explained.

At the beginning of the period of compression in the working cylinder a,-'after the closing of the one, or more scavengingair admission orifices a which takes place with a certain delay relative to the closing of the one or more exhaust ports aF, that is to say when the piston in its upward movement reaches the position 1:1 in the cylinder, insuch a Way as to ensure a full charge and even a supercharge in the cylinder,the fuel distributor commences to deliver the fuel, which determines the opening of the injection valve (l; The admission of fuel, between the flat valve d and its seating 6 takes place at first with a very small output, which proceeds to increase gradually. At this moment, the rich carburetted mixture, which is in the chamber 1) at a pressure very near the final pressure of compression, expands violently into the working cylinder a, passing beneath the valve cl and through the nozzles 0; these latter are formed and arranged in such a manner as to obtain the maximum transferespeed of the fluid for a fixed relation of the pressures respectively existing in the working cylinder a. and in the chamber b during the injection stage. This injection into the working cylinder takes place at the moment when the whole air is still in motion in the latter;

6; this equilibrium is afterwards'upset, the pressure becoming higher in the working cylinder. The delivery-speed of *the fuelpump is then accelerated the valve (1, of which the lift is then limited by its stop 6, is unable to rise further from its seating; the liquid fuel admitted by this valve is then squeezed or reduced to a film and atomized mechanically by the calibrated clearance formed between the small valve-guiding piston (Z and its housing b i The speedof the working piston increasing (for example when the piston has arrived at the position 2-2 in its upward stroke), by reason of the excess pressure in the cylinder a, the carburetted air passes at high speed through the nozzles or twyers 0, in a direction opposite to the flow of the carburetted mixture at the beginning of thecomp'ression stroke; this carburetted air carries along the greater part of the liquid fuel charge admitted by the valve J, diffusing this fuel in the chamber 6 wherein the mixture is vaporized; for this purpose, the

chamber is protected against external radiation by a casing h and is heated by an electrical resistance 2' arranged within the chamber 6; this resistance takes the form of con centric rings separated? by insulators and connected electrically on the one hand to the wall of the chamber 1), forming an earth return, and on the other hand to an electrical conductor 2 connected to any suitable source of current. This resistance, at the time of starting and at moments when it is necessary, is raised by the passage of a current to a temperature which ensures the maintenance Within the chamber 6 of a temperature favourable to the vaporization of 'the carburetted mixture contained in the latter, but lower than the point of ignition of the rich mixture compressed therein.

This chamber 6 might also be heated by a supply of exterior wheat or, previously to using heavy oil, by running the engine on motor spirit for some short time.

the cylinder a into the chamber b. The ignition of the charge is preferably carried out by means of one or'more high tension sparking plugs arranged atafi.

"Vaporization continues in the chamber 6.

during the whole of the time during which this chamber remains closed, that is to say during the period of combustion, expansion and exhaust, until the start of the following compression stroke, when the opening of the injection valve (Z allows the suitably vaporized carburetted mixture to return fromthe chamber 1) into the cylinder.

The chamber 12 should preferably'be of a shape ensuring a complete evacuation of the still liquid fuel during the injection into the working cylinder, at the beginning of the period of compression.

It is to be noted that the charge from the chamber 6 is in no way derived or drawn off from the normal cylinder-charge, because this chamber b discharges itself into the working cylinder when the latter has been completely filled, and when all the distribution orifices are closed at the start of the compression stroke, and an equivalent charge passes back from the cylinder into the mixing chamber at the end of the period of compression. There is thus a simple exchange of gaseous masses of different qualities without variation of quantity.

It may be remarked that the ignition is greatly facilitated by the fact that each time there is withdrawn from the cylinder a charge of carburetted air, which is injected anew into the working cylinder after vaporization in the mixing chamber before being ignited.

At the time of starting the engine, since the chamber 6 does not enclose ar'charge of carburetted air, there occur several up and down strokes of the piston in the cylinder before ignition takes place; the air compressed by the piston carries along and diffuses in the chamber liquid fuel squeezed out and atomized mechanically bythe valve d; the carburetted mixture is admitted into the cylinder at the beginning of the next compression stroke, merely to be forced back into the chamber 6 with a new charge of air and fuel at the end of the period of compression; these operations are repeated until the mixture is suiiiciently carburetted and sufliciently vaporized to permit its ignition.

There maybe mixed, with'the charge of carburetted air in the vaporization chamber,

a gas which would be diffused at the same time as the mixture, in order to activate the combustion of heavv fuel oils; this gas might also be a combustible gas.

In the case of, an engine ,with several cylinders, all the mixing and vaporizing chambers of the different cylinders may be connected together by pipes of very small sectional area, so as to equalize the pressures and the speeds of, injection between all the cylinders. 7

It is to be understood that without in any way departing from the .principle of the" present invention, numerous modifications in detail may be made in the form. of constr uction which has been illustrated and described by way "of example. Thus, one

'might employ another type of valve for the injection of the fuel, for instance those descrlberl in my prior patent speclfications Bro. 197,934: and No. 923,468.

\Vhat I claim is: I 1. The method of operating an internal combustionengine which comprises, providingtwo normally segregated bodies of gaseous nature, one body being located within the compression chamber of the engine, subject to compressive variations incident to the change of capacity of said compression chamber, and the other body being definitely bounded outside the compression chamber, placing said bodies into restricted communication during the compression stroke of the engine, thereby producing a tidal flow from the outside body to the one within the compression chamber on the early phase of the compression stroke, and in; contra-direction on the later phase of the compression stroke,

admitting liquid fuel under pressure in the form of a film to said. bodies at sald point of. restricted communication during the period of their tidal flow, and controlling the duration of said restricted communicatlon, thoroughly pulverizing said liquid fuel of restricted communication during period of their tidal flow, and controlling the by means of the tidal flow from the outside body to the one Within the compression chamber on the early phase of the compression stroke, and in contradistinction on the later phase of the compression stroke trapping the outside body of gaseous matter thus enriched with liquid fuel by positively cutting off said restricted communication just prevlous to the ignition point 1n said compression chamber and maintaining it cut off until the beginning of the next compresv sion stroke, and thoroughly vaporizing said trapped body of gaseous matter.

2. The method of "operating an internal combustion engine which comprises, providing "two normally segregated bodies of gaseous matter, one body being located within the compression chamber of the engine, subject to compressive variations incident to the change of capacity of said compression chamber, and the other body being definitely bounded outside the compression chamber, placing said bodies into restricted communication during the compression stroke of the engine, thereby producing a tidal flow from the outside body to the one within the compression chamber on the early phase of the compression stroke, and in contra-direction on the later phase of the compression stroke,

admitting liquid fuel under pressure in the fornn of a film to said bodies at said point the duration of said restricted communication, thoroughly pulverizing said liquid fuel by means of. the tidal flow from the outside body to the one within the compression chamber on the early phase of the compression stroke, and in contradistinction on the later phase of the compression stroke trapping the outside body of gaseous matter FRANQOIS ROGHEFORT.

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