US2387277A - Regulation of the combustible mixture for internal-combustion engines - Google Patents

Description

Oct. 23, 1945. P. LORANGE 387,2??? REGULATION OF THE COMBUSTIBLE MIXTURE FOR INTERNAL-COMBUSTION ENGINES Flled Oct 19' 1938 '4 Sheets-Sheet 1 Oct. 23, 1945.

7 N 0 P g P. LORANGE REGULATION OF THE COMBUSTIBLE MIXTURE FOR INTERNAL-COMBUSTION ENGINES Filed 061;. 19, 1938 4 Sheets-Sheet 2 Oct. 23,1945. E 2,387,277

REGULATION OF THE COMBUSTIBLE MIXTURE FOR INTERNAL-COMBUSTION ENGINES Filed Oct. 19, 1958 4 Sheets-Sheet 3 3 2 w a u g; a: u L

' o 3040 so 00- Horse Power- Km er Hour P. LORANGE 7 ,387,277

REGULATION OF THE COMBUSTIBLE MIXTURE FOR 1 INTERNAL-COMBUSTION ENGINES Filed 001;. 19, 1938 v 4 Sheets-Sheet 4 Patented Oct. 23., 1

REGULATION OF 2,387,271 THE COMBUSTIBLE. MIX- TURE FOR INTERNAL-COMBUSTION EN- GINES Prcsper LOrange, Stuttgart-Feuerbach, Ger- I many; vested in the Alien'Property Custodian Application October 19, 1938, Serial No. 235,881

, Germany March 2, 1936 9 Claims. (G. 123-139) This invention relates to apparatus forthe regulation of the combustible mixture for internal combustion engines. l The formation of the combustible mixture in internal combustion engines by means of carburettors has the advantage that the quantity .of fuel is proportioned directly to the quantity of air supplied, but suffers on the other hand from the drawbacks that the fuel has a free surface in the carburettor, that the carburettor is sensitive to position, and that the mixture is liable to be too rich at high speeds. The fuel pressures produced are also too low to effect suflicient atomisation, particularly if the fuel is in- Jected directly into the interior of the cylinder in contrast to injecting it into an induction pipe leading thereto.

With a view to retaining the above-mentioned advantages whilst avoiding the disadvantages it has been proposed to employ fuel pumps designed to give-a variable supply and regulated by means of apparatus influenced by the pressure of the air 1n the induction pipe of the engine. Such regulation cannot, however, be carried out sufliciently simply and sensitively.

According to the present invention, means for.

supplying fuel and air to an internal combustlon engine, comprises incombination an air passage along which the air flows in the operation of the engine; at'least one injection nozzle for the fuel, adapted "to deliver a charge thereof into the air, to be burnt in the engine; pump means arranged to supply fuel to the injection nozzle at a rate which is in excessof the rate at which the fuel is delivered fromthe nozzle;

derived from the motion of the air along the air passage and the resultant of which is directly proportional in magnitude to the rate of flow of said air, the pressures on the two sides respectively of the control member forming the pressure differ-- ential thereon being communicated to the memher from the air flowing along the passage.

In carrying the invention into effect the pressuredifierential derived from the motion of the air in the air passage may be caused to act either directly upon, or by producing a partial vacuum upon, a piston or a diaphragm surface so arranged that the force acting thereon influences the loading of the control valve (hereinafter referred to as the overflow valve) in the fuel pipe by which fuel is supplied to an injection nozzle or proportion to the quantity of air drawn into the] engine per unit of time, but the air pressure thereby produced increases as the square of the speed of flow. Consequently, the load on the an automatic two-way control-valve interposed between the pump means and the injection nozzle and connected to these parts by pipelines in such a manner that the excess quantity of fuel dehvered by the pump means is returned theretoby way of the valve, which valve comprises a movable valve element, the position of which in the valve determines the magnitude of excess of fuel that is-returned to the pump and 'correspondingly the quantity of fuel that is delivered from the nozzle; and loading means for the valve, adapted to load the same and thereby adjust the position of the valve element therein in accordance atall engine speeds and corresponding rates of flow of air along the air passage, with the rate of flow of said air, the -saiclioading means'comprising for this purpose a control member for the valve element which is movable, with consequent corresponding movement of the valve element, under the effect of a pressure differential upon it overflow valve, and therefore the pressure-in the fuel supply pipe, increases as the square of the air speed. The injection velocity of the fuel, however, corresponds to the square root of the pressure of the supply thereof and thus is proportional to the speed of flow. of the air.

.The regulation of the mixture in accordance with the invention can be effected whilst using either pumps with a uniform rate of delivery, for

example, gearpumps, or piston pumps having a separate piston for eachnozzle tobe supplied. In the first case, a decisive factor in the design is whether a carburettor delivering a uniform flow Y of mixture to a plurality of cylinders is to he replaced, or whether the fuel is to'be delivered to valve is necessary for all the pumps. In the SEC? ond case, no control of the injection valves need take place if a separate overflow valve is p 1 vided for each nozzle. On the other hand, if it'is desired to use a multiple cylinder pump with only one overflow valve, control of the injection valves is necessary. Sucha-control is frequently diflicult to provide for, however, particularly when the invention is to be applied to existing'types of engines. I v

According to a further feature of the invention,

therefore, when a multiple piston pump is employed with only one overflow valve, the control at the injection nozzles is effected by'the pump In order to efiect such control in a simple manner the piston of each pumping unit is utilised to control the communication between a pump delivery space common to all the pumping units, and

a nozzle corresponding to the said piston. In this case a given piston does not operate to convey the charge delivered thereby to the corresponding nozzle, =but actuates a control member which establishes a connection between the nozzle and the pump delivery space into which all the pumping units deliver, so that on the one handa portion of the discharge of the other pumping units passes through the opened nozzle and, on the other hand, the total discharge of the piston actually operating does not pass through the said nozzle.

The quantity of fuel supplied through an open nozzle is determined by the regulated pressure common to all the pump delivery spaces and by air flowing per unit of time. 1

Thus, according to one constructional embodimerit of the invention a constriction may be provided in the suction pipe, for example by means of a so-called Venturi tube, and a connection made between the position therein at which the air has its maxlmumvelocity and lowest pressure and the lower side of a piston or diaphragm regulating the overflow valve, the upper side of which piston is exposed to the pressure of the air in the suction pipe before reaching the constriction.

The overflow valve is thus loaded by a resultant pressure which, if necessary, may be increased by the pressure of a spring for the purposes hereafter described; the valve will therefore open as soon as the pressure of the liquid multiplied by the cross-section of the valve is greater than the resultant pressure acting on the regulating piston multiplied by the cross-section of the latter, plus the force of the spring.

The pressure of the liquid thus always remains proportional to the difference of pressure of the flowing air at the two points in the suction pipe to which the valve regulating device is conneci:

' and this ratio can easily be made very large, as

.otherdeflection surface, by which the current of air is deflected.

Such an arrangement can readily be so formed that there is no considerable loss of air velocity. It can also be conveniently designed to oscillate about a pivot and be made to act upon the overflow valve through a transmission mechanism.

The injection nozzle, when it is controlled, can be closed by a valve opening inwardly or outwardly. When the nozzle is not controlled it can, particularly when the injection takes place in the cylinder, be closed-by an outwardly opening needle' or by a spring-loaded check valve opening inwardly. The nozzle, however, can also be quite open, especially when it discharges into the suction pipe leading to the inletvalve.

If a controlled injection nozzle is used in conjunction with a pump having a uniform output,

the control may be effectedby means of a me-- chanical'control derived-from the cam shaft, and conveniently from the existing control of the inlet valve. 4

In addition to effecting a, control of the fuel supply in the manner already described it may I beneoessary or desirable to effect a correction of the richness of the mixture, the nature of the correction depending upon the particular circumstances or requirements, and further features of the invention are concerned with such corrections. Thus it is sometimes found that the quantity of fuel at higher engine speeds becomes too great as a consequence of the air attenuation then taking place, so that the mixture becomes too rich. In order to obviate this difficulty according to a further feature of the invention, the overflow valve, in addition to being loaded in accordance with the pressure of the airflow, is also loaded with an approximately constant additional force, for example by means'of a spring. It is ing-upon the pressure of the air flow, and supplied, for example, by a spring the tension of which is varied with the load. For this purpose the tension of the spring may be varied simultaneously with the adjustment of the throttle regulating the output, so that an additional initial tension is imparted to the spring when the throttle is slightly open and when it is fully open, but the tension is relieved in the intermediate position of the throttle corresponding for exampie, to the stage between sixty per cent and eighty per cent of the full load.

In still other cases, notably in the case of heavy motor vehicles, it may be desired that the mixture should be particularly rich at a certain speed, for example at the speed at which gear-changing takes place, and should become weaker with increasing speed. In such cases, according to another feature of the invention, the fuel curve is corrected for example, by employing the inertia of a centrifugal regulator, by loading the overflow valve with a force, additional to that depending upon the pressure of the air flow, which is influenced by the speed and increases or decreases therewith. In this way, a mixture can be produced which is richer at low speed and at maximum speed, but poor at intermediate speeds, or which is richest at any given speed.

. Another feature of the invention relates to the plied, and provided that the density of the air remains constant. The proportions of the mixture would not, however, remain constant with v variations in thealtitude at which the engine is operating, since, although the fuel pressure is reduced in direct proportion to the fall in air density, the quantity of fuel supplied per unit of time varies as the square root of the air density.

invention, this fault is corrected by reducing thewe force loading the overflow valve as the altitude j increases. This may be effected by applying an additional force having a negative action, the said I force being'provided, for example, by a diaphragm chamber, filled with air at normal atmospheric pressure so as to expand as the altitude increases, and arranged to reduce the load on the overflow valve when such increase takes place. If a supercharging blower is provided, the difference between .the blower pressure and the external pressure may be employed to produce the variation in loading of the overflow valve, the said difference in pressure being compensated for by a spring as is more fully. described hereafter.

In order that the invention may be clearly understood and readily carried into effect reference will now be made to the accompanying drawings,

in which Figure 1 illustrates diagrammatically an engine having a fuel supply installation according to the invention which embodies controlled injection nozzles and a fuel supply pump with a uniform output;

Figure 2 illustrates an arrangement for conconjunction with an intermittently discharging piston pump;

Figure 4 illustrates a modification of the invention in which several injection nozzles are supplied separately from the pumping units of a multiple piston pump and the operation of the nozzles is controlled by the pump pistons;

est point of which a connection is made with the underside of a regulating piston j which works in a cylinder 0 and is thus subjected on its-underside to the reduced pressure resulting from the partial vacuum at the point cin the pipe 1).. The upper end of the cylinder e is connected to the pipe at a point on the inlet side of the constriction c. The piston I is thus loaded in accordance with the difierence in the pressures in the pipe b at the point e and on the inlet side thereof. In ad- 1 dition the piston j is loaded by a spring 9 for effecting a correction of the fuel delivery. curve in a manner more fully described hereafter in connection with Figure 6 of the drawings. These loads are applied to the overflowvalve h which is made as a needle and closes the pipe is from The manner in which this construction operates is illustrated in Figure 6 of the drawings, in which the full linecurve A, B illustrates the increase of the fuel pressure p with the engine and air supply speeds, at aconstant position of the air throttle. By taking the square roots of the values for the pressure p given-by the curve A,

B, a curve E, F corresponding to the fuel in- :Iection velocity v is, obtalnedl This curve, as can be seen, is in the form of a straight line, indicating that the fuel injection velocity increases Droportionally to the engine speed.

Figure 2 illustrates one manner of controlling the injection valves d illustrated in Figure 1. In this construction, the valve is moved by the lever .o of thecylinder inlet valve, so that it is open during the whole or a portion of the suction period. By shifting a collar s, the period of-oper ing and the height of the opening movement of the valve d can be adjusted. The injection valve could equally well be controlled directly from the cam shaft t by means of cams and double armed levers. "The adjustment of the valve during working (for example, to obtain a weak or a rich mixture) could then take place, for example, by ad- 'Figure 5 illustrates in detail a construction of V a pumping unit and injection-valve control suitable for use in the embodiment illustrated in Figure 4.

of a fuel supply installation constructed in accordance with the invention, and one way in which the mixture proportions may be corrected. Figure 7 to 10 are further diagrams illustrating the correction of the mixture proportions to take account of difierent circumstances and conditions, and Figures l1, 12, 13 and 14 illustrate various modifications of an apparatus constructed according to the invention, designed to eiiecttho corrections illustrated respectively in Figures 7. 8, 9 and 10.

Referring to the construction illustrated in Fig ure 1 of the drawings, the four controlled injection valves d of an engine a are supplied with fuel from a pump 1 having a uniform rate of delivery, by means of a pipe n connected in parallel with the four injection valves (1. The pipe 11 is connected to an overflow pipe k. controlled by an overflow valve h, and leading to the supply tank and thence back to the suction side of the pump Z. There is inserted in the air. suction pipe b of the engine a a constriction c from the narrowlusting the lever fulcrum which in this case would be eccentric.

In the modification illustrated in Figure 3, the

during the corresponding suction stroke, so that there arises in the passage n a pressure propor tional to the square of the air velocity. When the pressure of the fuel exceeds this .value the valve portion thereof that the current of air deflected by the blade. 21 is caused to follow an S-shaped path. v

In usefthe pump is so adjusted as to commence its delivery stroke shortly after the com- A spring g is provided in this case also to' efiect a correction of the fuel delivery curve as described hereafter with reference to Figure 6.

The rebound surface it may also be made round and act directly on the needle 72..

The nozzle opening may also be closed by an automatic valve, especially when theinjection takes place in the cylinder itself.

In addition to effecting the correction described with reference to Figure 6, the spring g may be used to provide a supplementary load in order to compensate for a constant resistance in the injection pipe n or the nozzle (1, for example, the resistance of a spring-loaded valve therein. The fuel'pressure necessary for the opening of such a valve would then be determined by the spring g which would have to be' designed to provide a force corresponding to that pressure, in addition to the force required for effecting the correction of the mixture proportions.

In the modification illustrated in Figure 4 the air suction pipe 11 of a six-cylinder engine a is connected to a regulating device e, for exam-- ple of the form illustrated in Figure 1. The pressure of the fuel supply to the injection nozzles is produced by a multiple piston pump G, all the units of which discharge into the same delivery space D which is connected by a pipe is to the overflow valve of the device e. The pressure in the delivery space of the pump G is thus kept at a level corresponding to'the square of the quantity of air supplied per unit of time. The outflow of the excess fuel from the device 6 takes place through the pipe Eto-the pump suction pipe m.

The pistons L of the pump G are so" adjusted that each piston reaches the end of its discharge stroke approximately at the mid point of the in- Jection period of the corresponding injection valve.

During th compression stroke of a given piston L a pressure valve H opens, but the stroke of the said valve H is limited by avalve J, which is-held on its seat by a strong spring. At the end of the compression stroke, however, the piston L positively engages the valve H and thus lifts it and the valve J by a small amount, so

that during this period the pressure space D is connected to the pipe I (or II, III, IV, V,or VI as the case may be) supplying the left hand end injection nozzle :1.

The construction of one of the pumping units diagrammatically illustratedin Figure 4 is more clearly illustrated in Figure 5. In this construction the pump housing G contains a piston guide K in which the piston L slides. In the position shown, the piston L is at the upper end of its stroke and has lifted, by means of an extension 8. the pump discharge valve H and with it the control valve J, so that the passage in the union- R is connected to,the pumpdelivery space I) and with the overflow valve of the regulating device e. The valve J is'moved against the pressure of a strong spring P, so dimensioned as'to 4 additional to the load derived from the maintainthe valve J closed against the highest fluid pressure arising beneath it.

The delivery valve H is fitted in a screwthreaded body M which bears upon the piston guide K and is closed at the top by a cap N. The control valve J moves in a guide member 0 which is tightly screwed into the cap N. The height of opening of the control valve J can be determined by the thickness of a packing T.

In place of a control valve J of the form illustrated, a ground slide valve may be employed.

In each of the constructions described, since the loading of the overflow valve is derived from the pressure diiierential hereinbefore referred to, the connections for utilising that energy can be made in front of or behind the air throttle. Similarly, the injection nozzle, when fitted in front of the air inlet valve, can be inserted at any position in the suction passage in front of or behind the air throttle.

As has already been pointed out, it may be necessary or desirable to correct the proportions of the mixture to take account of different circumstances. Thus, it may be found that the quantity of fuel at higher engine speeds becomes too great as a consequence of the air attenuation then taking place, so that the mixture becomes too rich. This dificulty is met by the provision of the spring g illustrated in Figures 1 and 3, which acts to apply an approximately constant load to the overflow valve 71. ressure of the air how. The effect of such a ditional load can be seen from Figure 6, in which the addition of the load pe produces the final fuel pressure curve indicated by the broken line C', D'. By taking the square rootsof the values given for the pressure (p+pe) by the curve C, D, the curve G, H is obtained which, as can be seen from the drawings, has a downward concavity, in contradistinction to the straight line curve E, F. that is, the rate of increase of the fuel injection velocity is not directly proportional to the engine speed but decreases somewhat as the engine speed increases. It is easy by the choice of a spring of appropriate strength so to adjust this relative decrease of the fuel injection velocity as to permit the maintenance of a mixture of uniform proportions at all engine speeds.

Figure 7 illustrates a case in which the mixture proportions are corrected so that the mixture is richer-with light and full load than with intermediate loads, as may be required, for example, in an aircraft engine. In theflgure the continuous curve 1 represents the variations of air pressure behind the throttle and, consequently, of the rection is applied, said curve b being proportional.

- to the curve 1 The supply should, however, comply with the curve b'-, that is to say, the mixture should be richer with no'load and with full load than with intermediate loads. r

This may be achieved, for example, by the apparatus illustrated in Figure 11, which comprises a regulator 9, operating similarly to the regulator illustrated inFlgure 1, and having an overflow needle h loaded by a diaphragm f, the upper side of which is connected'to a region of high-pressure in the air supply passage, while the lower side thereof is connected to a region of lower pressure. The said diaphragm j is further loaded by a spring 9, the-upper abutment of which is formed by the displaceable piston in the casing cover e The piston g is displaced by a cam disc 9 v and the spring g is tensioned as soon as the cam disc, which is connected to the throttle valve A- the cam disc g by means of a piston which is loaded on one side by the pressure of the air supply in front of the throttle and on the other side the-throttle.

Figure 8 illustrates a correction whichis suitable, for example, for the engines of heavy motor vehicles. In this case, the additional output and consequently the increase in the supply is provided, as indicated at b at a road speed at which gear-changing takes place after which a rapid increase in the torque is necessary. The correction indicated in Figure 8 may be obtained by means of the apparatus illustrated in Figure 12 which comprises a centrifugal regulator g which actuates a cam disc o through a lever g and connecting rod g in a manner similar to that illustratedin Figure'll. When the regulator g rises owing toan increase in the speed, the cam disc 9 is thereby displaced to the left and so reduces the spring tension. When the regulator 9 descends, the cam increases the tension of the spring and consequently the supply of fuel.

If the engine is to be used at considerably varying altitudes it is desirable to effect acorrection to compensate for the change in the air density, the reduction of which from a, very low altitude up to an altitude of 12 kilometres is indicated by the curve I in Figure 9. The reduction in pressure of the fuel supply, however, follows the curve 12 if no correction is applied, and thus differs in creasingly from the air pressure with increasing altitude. The present invention provides a correction of the fuel pressure whereby the curve 1) is obtained, which provides a sufficient approximation of the fuel pressure variation to the air density variation.

as is indicated in Figure 9. If, at this point, the

, action of the diaphragm chamber e is replaced by that of a small piston which is loaded-on one side by the external air pressure and on the other side by the pressure of the air supply, an effect can be obtained which is similar to that produced by the diaphragm chamber f illustrated in Figure.

13, so that the fuel curve b is corrected at its right hand end to the form of the curve b. This result is obtained if the correcting -piston is rendered operative, for. example by means of the regulator of the supercharger, only when the by a spring and by the negative pressure behind given maximum altitude of 6 kilometres has been exceeded. However, it is advantageous for this correction also to be rendered effective before the said altitude has been attained as is indicated in Figure 10. This is due to the fact that-if the air supply pressure is maintained constant up to the said maximum altitude, the quantity of fresh air charged does not remain constant, but is in creased by an amount varying from approximately 20% until the said altitude is reached, owing to the influence of residual gas and temperature. By applying the correction referred to, however, the air supply pressure curve and the fuel supply curve are corrected to the form of the curve I and the left hand end of the curve b.

Since the differential pressure increases when descending from the said maximum altitude, that is to say from 6 kilometres in this case, the arrangement also produces the correction when deeeending from that altitude.

An apparatus suitable for effecting the correcuon illustrated in Figure 10 is illustrated in Figure 14, in which a piston B and spring B, which are both enclosed in a cylinder B act.on a regulator diaphragm Lsuch as is illustrated in Figure 11,

' through a connecting red C.

. A device suitable for this correction is illustrated in Figure 13, in which a diaphragm chamber f is mounted on the cover e of a regulator casing e of the form already described, the said diaphragm chamber f acting, through a lever f and a connecting rod f on the regulator diaphragm and expanding with increasing altitude,

' due'to the decreasing air density, so as to reduce the load on said regulator diaphragm.

portion as the external air pressure, as indicated by curve I. The device illustrated in Figure 1 of the drawings would provide a mixture of the correct proportions up to the said maximum altitude, (curve I1 and b but as indicated by the curve b would then produce the same deviation The space above the piston B communicates through a passage B with the space above the regulator diaphragm f and thus with the air suption illustrated by Figure 7 may be employed,

simultaneously with the altitude correction illustrated by Figure 10. In such a case, in addition to the piston B loaded with the differential pressure, there would be a, spring of variable tension acting on the regulator diaphragm and controlled as in Figure 11. Alternatively the tension of the spring B below the piston B would be controlled to produce the correction indicated in Figure 7.

. supply decreases substantially in the same pro- 1 I claim:

1. Apparatus for supplying fuel and air to an.

internal combustion engine comprising in combination an air passage along which air flows to let connected to said injection nozzle 'for supplying fuel thereto at a rate which is in excess of that required for normal operation of said engine; a control valve connected between the outlet of said pump and said source of fuel, said 1 valve, when closed, causing complete delivery of fuel from said pump to said injection nozzle and, when open, causing the return from the outlet of said pump to the source of fuel of the amount of fuel in excess of that required for the operation of the engine; and actuating means for said control valve comprising a closed casing, and a pressure responsive device connected to said valve and positioned within said casing between the upper and lower ends thereof to define upper and lower chambers within said casing, said upper chamber communicating with said air passage at a point in advance of the apertured constric- 1 tion therein and said lower chamber communicating with the apertured constriction, opposite sides of said pressure responsive device being acted upon by pressures derived from the motion of air along the air passage in advance of the throttle valve within said passage, the resultant of which pressures is directly proportional in magnitude to the rate of flow of said air whereby the valve is opened and closed in accordance with pressure difierentials derived from the motion of the air along theair passage in advance of the throttle valve therein.

2. Apparatus for supplying fuel and air to an internal combustion engine as specified in claim 1, wherein the engine is of the multiple cylinder type and wherein the pump comprises a multiple piston pump, the pistons of which correspond respectively to the number of injection nozzles, there being a. pressure chamber incorporated in the pump into which all of the pistons thereof discharge, a connection between the pressure chamber and each of the nozzles, and control means operated by each of the pistons of the pump during the discharge stroke of the piston to open the connection to the corresponding nomle.

3. Apparatus for supplying fuel and air to an internal combustion engine as specified in claim 1, wherein the engine is of the multiple cylinder type and wherein the pump comprises a multiple piston pump, the pistons of which correspond respectively to the number of injection nozzles, there being a pressure chamber incorporated in the pump into which all of the pistons thereof discharge, a discharge valve for each pump cylinder co-operating with the piston therein and positively opened thereby during the discharge stroke, and a control valve co-operating with each discharge valve and operated thereby when the discharge valve is opened by the piston, so as to provide communication between the pressure chamher and the corresponding nozzle.

5.Apparatus forsupplying fuel and air to an internal combustion engine as specified in claim 1, wherein the control valve is movable under the eiTect of a. force additional to that derived from the pressure diiierential exercised upon the pressure-responsive device, which additional force is exercised by a spring having means for varying automatically in accordance with a predetermined condition arising during operation of the engine incorporating the apparatus, the force it applies to the control valve.

6. Apparatus for supplying fuel and air to an internal combustion engine as specified in claim 1, wherein the control valve is movable under the effect of a force additional to that derived from the pressure differential exercised upon the preston pump, the pistons or which correspond reher-and each of the nozzles, and control means operated by each of the pistonsof the pump during the discharge stroke of the piston to open the connection to the corresponding nozzle, and

the arrangement being such that each piston of the pump is caused to reach the end of its discharge stroke at the mid-point of the injection period of the corresponding-nozzle.

4. Apparatus for supplying fuel and air to an internal combustion engine as specified in claim 1,

wherein the engine is of the multiple cylinder typ and wherein the pump comprises a multiple pissure-responsive device, which additional force is exercised by a spring having means for varying in accordance with the opening \of a throttle in the air passage, the force it' applies to the control valve.

'1. Apparatus for supplying fuel and air to an internal combustion engine as specified in claim 1, wherein the control valve is movable under the effect of a force additional to that derived from the pressure differential exercised upon the pressure-responsive device, which additional force is exercised by a spring having means for adjusting its tension, the adjusting 'means for the spring being operatively connected to a throttle valve in the air passage so as to be operated simultaneously therewith.

8. Apparatus for supplying fuel and air to an internal combustion engine as specified in claim 1, wherein the control valve is movable under the efiect of a force additional to that derived from the pressure diflferential exercised upon the pressure-responsive device, means being provided for varying the said additional force in accordance with variations in the altitude at which the engine sure-responsive device,- means being provided for varying the said additional force in accordance with variations in the altitude at which the engine incorporating the apparatus is-operatlng. which means comprises a barometric capsule,

PROSPER L'ORANGE.

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