US2493587A - Carburetor - Google Patents

Description

L. LEEJI CARBURETOR Jan. 3, 1950 5 Sheets-Sheet 1 Filed Sept. 28, 1943 ('1 INVENTORD LE/gHm/v LEE l? BY- L. LEEJI: CARBURETOR 'Jan'. 3, 1950 3 Sheets-Sheet 2 Filed Sept. 28 1945 can don mom v mmN INVE NTO R L E/yHTU/v Lit/1Z7 AGENT L. LEE, IE 2,493,587

CARBURETOR 3 Sheets-Sheet 3 Jan. 3, 1950 Filed Sept. 28, 1945 INVENTOR v NE AGENT MEI- 552 odd F1 mokk NUZNU N Y Patented Jan. 3, 1950 UNITED STATES PATENT OFFICE mesne assignments, to

Niles-Bement-Pond Company, West Hartford, Conn, a corporation of New Jersey Application September 28, 1943, Serial No. 504,098

31 Claims.

The present invention relates to carburetors and particularly to carburetors of the type in which the quantity of fuel supplied to the engine is proportioned with respect to the quantity of air supplied.

It is an object of this invention to provide improved means for controlling the quantity of fuel supplied to an internal combustion engine as a function of the quantity of air supplied to support combustion of that fuel.

Another object of the invention is to provide an arrangement wherein the quantity of fuel supplied to an internal combustion engine is electrically controlled. A still further object is to providean electrically operated carburetor in which the fuel flow is controlled in accordance with the resultant of a number of variable conditions, such as air flow, air density, and intake manifold pressure.

. Another object is to provide an electrical carburetor in which the quantity of fuel flowing to the engine is not affected by variations in the voltage of the source of electrical energy.

Another object is to provide improved electrical flow controlling means for a carburetor, including means responsive to the acceleration of the engine on which the carburetor is mounted for enriching the fuel and air mixture upon such acceleration.

A further object of the present invention is to provide electrical means for controlling the flow of fuel to an internal combustion engine, wherein means is provided so that upon failure of the electrical power supply, the engine receives a quantity of fuel sufficient to operate it at a predetermined proportion of its rated output.

A further object of the present invention is to provide improved means for indicating various operating conditions of an internal combustion engine, such as fuel flow, fuel to air ratio, horse power output, and brake mean effective pressure.

Other objects and advantages of the present invention will become apparent from a consideration of the appended specification, claims and drawings, in which Figure 1 is a somewhat diagrammatic illustration of a carburetor with an electrical control system embodying the principles of my inven tion,

Figure 2 illustrates a carburetor provided with a modified form of electrical control system,

Figure 3 is an electrical wiring diagram of a control circuit shown in Figure 2,

Figure 4 is a somewhat diagrammatic illustration of an electrical system for indicating various engine conditions which may be used with the carburetor of Figure 2, and

Figure 5 is a somewhat diagrammatic illustration of another form of electrical control system for a carburetor.

Referring now to Figure-1, there is shown a carburetor body It, thru which air flows from an inlet ll past a Venturi restriction l2, and thru a passage M past throttles l5 and a discharge nozzle I6 to an outlet H.

A portion of the air entering the inlet I I enters impact tubes l8 whose open ends extend into the path of that air, and from these impact tubes flows thru a second passage which terminates at the throat of venturi l2. This second air passage may be traced from the impact tubes l8 thru a vent ring 20 which interconnects the tubes l8, a conduit 2|, a boost venturi 22 and a conduit 23 to the throat of the main venturi I2.

The conduit 2| is connected thru a conduit 24 to the interior of a flexible bellows 25 mounted inside a casing 26. The interior of casing 26 is connected thru a conduit 21 to the throat of boost venturi 22.

In accordance with the known principles of fluid flow, the pressure differential between the impact tubes [8 and the throat of venturi I2 is a measure of the velocity of air entering the engine thru the carburetor Ill. The boost venturi '22 is provided to amplify this pressure differential. The bellows 25 is exposed to the amplified pressure differential, and therefore expands and contracts in accordance with the changes in the velocity of air flowing thru the carburetor. The free end of bellows 25 is connected thru a link 28 to a pivoted arm 30, which insulatingly carries at its free end a slider 3| which cooperates with a slidewire resistance 32. This slider 3| is connected thru a pig tail connection 33 to a ground connection 34. The position of the sliding contact 3| along resistance 32 is determined by the differential pressure acting on the bellows 25, and hence by the velocity of air flowing thru the carburetor.

Conduit 2| is also connected thru a conduit 35 to the interior of a casing 36 in which a sealed bellows 31 is mounted. The bellows 31 is connected thru a link 38 to an arm 40 which is pivotally mounted at one end, and. carries at its free end a sliding contact 4| which cooperates with a slidewire resistance 42. The position of contact 4| along resistance 42 is determined by the absolute pressure in the casing 36, since the bellows 3'! is sealed. The slider 4| is therefore positioned in accordance with the variations in the absolute pressure in the inlet II, which pres sure is transmitted to the interior of the casing 36 thru vent ring I8 and conduits 2| and 35. The bellows 31 may be filled with nitrogen or other suitable temperature responsive fluid, in order that the position of contact 4I may also reflect temperature changes.

The fuel entering the carburetor comes from a pump or other source of fuel under pressure (not shown) and flows thru a conduit 43, past a valve 44, a metering restriction 45, another valve 46, and a conduit 41 to the discharge nozzle I6. The meteringrestriction 45 is intendedas a more or less diagrammatic representation of ajet system which may include a number of individualrestrictions, either fixed or variable.

The valve 44, which is balanced against inlet pressure, is carried by a flexible diaphragm 48, one side of which is exposed to the pressure of the fuel on the outlet side of valve 44, and the opposite-side of whichis vented at. 50. This vent may be to the atmosphere, as indicated in the drawing. or -mo1e preferably to the rent ringi 2.0. The. diaphragm 48 also carries an armature I, which cooperates with an electromagnetic coil 52. A spring 53. biases the diaphragm '48 for movement to the right,;in the opening direction of valve 44. "Thea-rmature 5| has its magnetic center-to thedeft of center of coil 52, so that energization of that coil tends to cause move-;

ment ;of armature 5| ;to the. right, thereby applying .anaadditional opening force to the valve 44,-and causing, an increasev in the pressure at the inlet side of the restriction .45.

The:valve. 4.6, whichis balanced against outlet pressure, is .carried by arfiexible diaphragm 54, one-side'of-which subjected to the pressure on the inlet-side of valve :46 and whose opposite side is ventedat 55. .Asinqthecase of .vent50, the-vent;55smay b e-:connected eitherto atmosphere 01;{120 ,vent ring20. However the vents 50 and ,55 should beconnected to the same source of pressure. The diaphragm 54 also carries an armature 56 which cooperates with an electromagnetic coil 51. 'A' compression spring 58 biases the. diaphragm 54 .for movement to the left, in the closing direction ;of-. valve 46. The magnetic center ofarmature-56isto the rightof ,the cen-- ter ofcoil '51, so that .uponenergization of coil 51, any additionalclosing-force isexerted on valve 56, causing the fuel pressure torise on the .discharge-side of the restrictionv45.

Thethrottles .15 are carriedby shafts'60 and 6I,2on;which are. fixedmatmg gears 62 and 63, respectively. The gearsJiZ ,-and..63 are driven thru. another gear 64-. which meshes with gear. 52, andis fixed. on a shaft 65 driventhru a. reduction gear (not shown) .by-ianelectricalmotor generally indicated at..66. The motor 66 is illustrated as. being of'the series wound :type, and is pro-- vided with an ;armature.. 61 and a pair of field windings 68 and 69.. .Iheenergization of motor 65 is controlled by. a-switchmechanism generally indicated at H. The-switch mechanism TI is operated in accordance' with the balance. between an evacuated bellows14and a-bellows'12 whose.

i on itsexterion. .Ihebellowsir14,:which isevac:

rfixing the yoke member I40 in any adjusted o position. Since the effects of variations in atfor a purpose to be described hereinafter.

7: operatingwith resistance I.48.

mospheric pressure on the bellows 12 and 14 .act in opposition toeach other, as far as the position of rod 15 is concerned. it may be seen that rod 15 is positioned in accordance with the absolute pressure in the mixture outlet I1.

The' rod 1.5also.carries a sliding contact I42. which cooperates with a slidewire resistance I43, The resistance I43 is mounted on a base I44 adjustable;in;a set oiguidesl45. One oftheguidesis provided with ,a set-screw I40 for locking thebase I44-in any adjusted position.

An. acceleration. control unit 11 includes apair of flexible bellows 18 and 80. The free ends of theibellows 18 and support. an arm M which insulatingly carries a sliding contact'82 cooperating. with aIslidewire resistanceelement 83. The interior of bellows 80 is connected thru aconduit 84 to the mixtureoutletjfl downstream from the throttles I5. Theinteriors of; bellows .1'81and 00 are connected-:by a restricted passage 8.5 of less capacity than thexconduit 8.4. The construction issuch that upon an increasein pressure at the mixture outlet.:I1, such-asaccompaniesan opening of .the. throttles, .the bellows 80 expandsmore rapidly thanthebellows 18, due. to the restricted communication between the bellows, thereby moving the arm 8.! andcontact82 to theleft. Since contact 82 is connected tothe right. end of resistance vI33, the resistance between thezterminals of183 is-thereby decreased. The resistance of element 83 is therefore decreased upon .accleration. Likewise, the resistance of element 83 isincreased upon deceleration.

A manual control unit generally indicated at 86 includes a mixture control 81, a priming. control 88 and a cut oif control 89. The mixture control 81 includes a contact 90 movable along a slidewire resistance 9'I. 'Thepriming control 88 includes a contact 92 movable along a slidewire resistance 93. The cut-off control 89 includes a contact I26 movable along a slidewire resistance I21.

A resistanceelement I48 is varied by a control device I50 in accordance with the quantity of fuel flowing thru the restriction 45, as measured by the pressure drop across that restriction. The device I50 includes a casing I52 enclosing afiexible' bellows I54. The interior of bellows I54 isconnected thru a conduit-I56 to the fuel supply line at a'point downstream from the restriction :45, while the exterior of bellows I54 isexposed-to the pressure in the interior of casing I52, which is connected thru a conduit I58 to the fuelsupply line at a-pointupstream from the'restriction '45. The expansion and contraction-of bellows I-54'therefore depends .uponthe pressure difierential across the restriction. 4.5.. The :free. end of bellows I54, whose-position depends upon the. expansion and contraction of the bellows, is attached to a link I60, whose opposite end is attachedrto a pivoted. arm I62,-'-which insulatingly carries at its enda contact I64 co- .Contact .I'641is.

connected to the right end of resistance I48. An increase in the pressure differential across restriction 45 causes a contraction of the .bellows I54 and a consequent movement of arm I62 to the right, thereby increasing the proportion of the total resistance of element I48 which is effective in the circuit connected to its terminals.

Operation of Figure 1 The energization of coil 52 which operates the valve 44 of Figure 1 is controlled by two electrical circuits, of which one, hereinafter termed the main energizing circuit, may be traced from the right hand terminal of a battery 94 thru a conductor 95, coil 52, a conductor I66, resistance I48, a conductor 96 to a junction 91, thence thru three parallel branches to a junction 98, and thence thru a conductor I00, contact 4I, resistance 42, a conductor IOI, resistance 32, contact 3I, conductor 33 and ground connections 34 and I02 to the left terminal of battery 94. One of the three branches between junctions 91 and 98 may be traced from junction 91 thru a conductor I03, resistance 9I and a conductor I05 to junction 98. A second of these three branches may be traced from junction 91 thru a conductor I06, a fixed resistance I01 and a conductor I08 to junction 98. The third of these three branches may be traced from junction 91 thru conductors I06 and I04, sliding contact I42, resistance I43; and conductors H0 and I08 to junction 96.

As previously described, an increase in the energization of coil 52 causes an openin movement of valve 44 and hence an increase in the pressure of the fuel on the inlet side of the restriction 45 and a consequent increase in the quantity of fuel supplied to the engine. In the main energizing circuit for coil 52, there are five variable resistances which control the current flow thru that circuit in accordance with five variable conditions. These five resistance elements are the resistance 32 which is varied in accordance with the quantity of air entering the carburetor, the resistance 42 which is varied in accordance with the pressure of the air in inlet II, the resistance I48, which is varied in accordance with the quantity of fuel flowing thru restriction 45, the resistance 9|, which is manually variable to control the fuel to air ratio, and the resistance I43, which is variable in accordance with the pressure in the intake manifold of the engine.

These five resistances are proportioned with respect to each other so that the resistances 32 and I48 predominate. The resistance 32 decreases with increasing air fiow, so that an increased air flow results in an increased current flowing thru the coil 52 and a consequent increase in fuel flow. The increased fuel flow acts thru the controller I50 to increase the resistance I48 and thereby reduce the current flow thru coil I52. An increase in air flow therefore causes an increase in the current flowing thru coil 52, which results in an increase in the fuel flow and thereby in an operation of resistance I48 to again decrease the current thru coil 52. The increase of resistance I48, altho proportional to the decrease of resistance 32, is less than that decrease, so that the net result is an increase in the current flow thru coil 52 and hence an increase in the fuel flow thru valve 44. Furthermore variations in fuel flow thru the restriction 45 due to extraneous causes produce a corrective effect in the current flow thru coil 52 which tends to reduce or eliminate such variations.

The pressure differential between inlet II and the throat of venturi I2 is a measure of the velocity of the air passing thru the carburetor, rather than the mass of that air. If the density of the air decreases, and the mass of the air passing thru the carburetor remains constant, the velocity of the air must increase to maintain the constant mass, thus causing the pressure differential between the inlet II and the throat of venturi I2 to increase and thereby causing a decrease in resistance 32. Since the object of this system is to proportion the mass of the air to the mass of the fuel, the system must be compensated for those variations in resistance 32 which are caused by variations in density of the air. This compensation is provided by the resistance 42, which is increased in response to a decrease in density of the air so as to counterbalance the decrease in resistance 32 caused by the decrease in the air density.

A mixture control 81 is provided so that the current flow thru coil 52 may be manually varied by moving contact along resistance 9|. By manipulation of the mixture control 81, the fuel to air ratio obtained with a given air flow may be varied at the will of the operator.

The resistance I43 is varied in accordance with the pressure existing in the air induction system at a point downstream from the throttles I5. This point is illustrated in the drawing as being in the mixture outlet H, but it may with equal or even greater facility be located in the intake manifold of the engine. As the pressure in the mixture outlet II increases, the contact 42 is moved to the left along resistance I43, thereby decreasing the resistance I43 and increasing the fuel to air ratio. Since the pressure in the mixture outlet II varies substantially directly as the power output of the engine, it may be seen that the resistance I43 acts to enrich the fuel and air mixture as a function of the power required from the engine. It has been found that engines operate with less tendency to overheat at high power outputs if they are supplied with a rich fuel and air mixture than if the mixture is lean at such times. The variable resistance I43 and the mechanism which operates it have been provided in the present system to insure the supply of a rich mixture under such conditions.

The motor 66 is controlled in a manner to maintain a constant absolute pressure in the mixture outlet IT. The particular pressure value which this system maintains at outlet I! may be adjusted by any suitable means. For example, it may be adjusted by changing the position of yoke I 40 which carries the stationary contacts H2 and H8. When the pressure in the outlet I1 decreases, the bellows I2 expands, thereby'moving switch contact III into engagement with stationary contact 2. This completes an energizing circuit for field winding 68 and armature 61 of motor 66, which may be traced from the lower terminal of a battery H3 thru a conductor I I4, switch contracts III and H2, a conductor II5, field winding 69, armature 61, and a conductor II6 to the upper terminal of battery II3. Energization of field winding 68 and armature 61 causes motor 66 to rotate in a direction to close the throttles I5, thereby causing the pressure in outlet I! to decrease toward its former value. In response to this decrease in pressure, the contacts I II and I I 2 are again separated, deenergizing motor 66.

In a similar manner, if the pressure in outlet flows out thru a conduit 209, valve 201 and conduit 208 to the throat of venturi 262. At the same time, a valve 219, located in conduit 223 and operatively connected to valve 201, is rotated so as to close conduit 223.

The resistance elements 213, 2H and 221 are connected in a Wheatstone bridge circuit which is illustrated more conventionally in Figure 3. This bridge circuit has a pair of input terminals 230 and 23I which are connected by conductors 232 and 233 respectively to the terminals of a battery .234. The bridge circuit also has output terminals 235 and 236, which are connected to input terminals 26I and 262, respectively, of an electronic amplifier generally indicated at 260.

The resistance elements H3, H1 and 221 are located in the lower right, upper right and lower left branches, respectively, of the bridge circuit, as viewed in Figure 3. The upper left branch of the bridge circuit includes a manually variable resistance 238 which serves as a mixture or fuel to air ratio control, as explained hereinafter. The bridge circuit also includes a resistance 240, along which a sliding contact 230 is moved by a controller 24l in accordance with the quantity of fuel flowing thru the carburetor, as hereinafter described. The contact .230 also serves as an input terminal of the bridge circuit. A portion of resistance 240 is connected in the lower left branch of the bridge circuit and the remainder is connected in the lower right branch, the relative magnitudes of the portions connected in the two branches being determined by the position of contact 230.

Referring again to Figure 2, it may be seen that all three of the resistance elements 2l3, 2H and 221 are continuously connected to the battery 234. These resistances are of some material such as nickel, having an appreciable temperature coefficient of resistance, and are so designed and proportioned with respect to the voltage applied to their terminals that they tend to heat up due to the current flowing thru them. The resistance elements are cooled, however, by the air flowing past them so that their respective resistance values vary inversely as the quantities of air flowing past them.

The quantity of air flowing past resistance element 2l3 depends upon the pressure differential across the throttle 2l6. differential varies inversely as the load on the engine, so it may be seen that the resistance of element 213 decreases when the load on the engine decreases and in general varies directly as the load on the engine, as measured by the throttle position.

The air fiow past the resistance element 211 is controlled by the density of the air. It may be seen that upon increasing density, the bellows 226 tends to collapse, thereby opening the valve 225 and increasing the air flow over the resistance element 2|1, thereby lowering the temperature of that element and decreasing its resistance. The resistance of element 2 I 1 therefore varies inversely as the air density.

The air flow over the resistance element 221 is a measure of the quantity of air flowing thru the passage 2!, and varies directly as a function of that quantity. Therefore, the resistance of element 221 varies inversely as the air flow.

In Figure 2, the fuel flows from a tank (not shown) thru a conduit 250, an engine driven fuel pump 25!, a conduit 252, a gear pump 253, mechanically connected to an electrical motor 254, a metering restriction 255, a pressure regulator This pressure 6 iii j 255, and a conduit 251 to a discharge nozzle s. Other suitable apparatus for supplying fuel to the engine may be used in place of nozzle 258, as for example, a direct injection mechanism or a spinner injector associated with a supercharger.

The output of pump 25| is controlled by a relief valve generally indicated at 2-65. The relief valve 265 includes a valve member 266 attached to a diaphragm 268. The valve member 266 is biased toward closed position by a spring 261. The diaphragm 268 separates a pair of expansible chambers 218 and 286. The pump discharge pressure is supplied to chamber 280 thru a conduit 282, and the chamber 218 is vented to conduit 285 by a conduit 269. The discharge pressure of the pump 25! is maintained at a substantially constant value by the action of relief valve 265, which value depends upon the strength of spring 261. Altho the pump 25! is illustrated as being of the rotary sliding vane type, any type of pump adaptable to provide a constant pressure output would be equally suitable.

The energization of motor 254 is controlled by amplifier 260, having input terminals Ni and I 262, which are connected to the output terminals 235 and 236 of the bridge circuit shown in Figures 2 and 3, as previously described. The amplifier 268 has output terminals 263 and 264 which are connected to the motor 254.

The pressure regulator 256 includes a housing 216 divided by flexible diaphragm 21! into a pair of expansible chambers 212 and 213. The chamher 212 may be vented thru a conduit 214 to the conduit 265. The diaphragm 21l carries a valve member 215 which is balanced against outlet pressure. A spring 216 biases the valve 215 for movement toward closed position. The function of pressure regulator 256 is to maintain a substantially constant pressure on the downstream side of the metering restriction 255 regardless of the pressure in conduit 251 so that the fuel flow thru thatv restriction may be controlled by the pressure applied to its upstream side by the pumps 25! and 253. Since both pump relief valve 265 and the pressure regulator 256 are vented to the conduit 205, it may be seen that variations in the pressure at the inlet of passage 20l have no effect on the fuel flow. For example, an increase in atmospheric pressure would act on the pump relief valve 265 to increase the pump discharge pressure. This would be counteracted, however, by the action of the increased atmospheric pressure on the pressure regulator 256 to increase the pressure on the downstream side of restriction 255. The operation would be similar if both chamber 218 of relief valve 265 and chamber 212' of pressure regulator 256 were vented to the outlet of a supercharger supplying air to the inlet of passage 2!.

The controller 241 which moves contact 230 along resistance 248 includes a bellows 284 fixed at one end to a casing 286. The interior of bellows 284 is connected thru a conduit 288 to the downstream side of the restriction 255. The interior of casing 286 outside the bellows 284 is connected thru a conduit 290 to the upstream side of restriction 255.

A restriction 282 interconnects the conduits 288 and 266. Restriction 292 may be opened or closed by a valve 284. Valve 294 is biased to closed position by a spring 296, and may be operated to open position by energization of a solenoid 298.

An energizing circuit for solenoid 298 may be traced from the left hand terminal of a battery wanna-5.87

1 l 3Blithru a conductor ABL-raeSWitch 302,.a con- -.du;ctor -3 03, solenoid 2 98; and;ground-connections 3M and 3fl5i-to tthe rightlhandlterm-inal-cf.battery 3(10.-- Althothe batter-y 3004s illustratedas being vseparate from the battery 234;it-is-preferahle to 1 use the same source of power for all theielectric i circuits. in this. system; :so that: upon .failure of .thatsource'for any reason, theesolenoidtz98 will be; deenergized.

.A.-resistance -e1ementr30fi=is mounted-in; sham-c accordance .with-ltheknown principles-10f ber H8 and -is. connected .thru. a conductor 3B8 in series with ya resistance-element 3m. mounted in chamber-@228. -A series circuit including the =-two .resistance :elements.-305+ and 3 HJ- may be autilizedto-operate an indicator. either-quantity of airenteringthe.carburetor, as described below insconnection with Figure-4.-

Operation of Figure 2 bridge:v circuits, zazehangeeintthe.resistance .of-"s elerment 2 H: has the same-.efi-ect on the--bridge1 circuit-asia similar change in'rtheresistanceot-ele- .ment 221.. ;-As; previously-stated;theresistanee. of element 2 l1 varies inverselyiwith theadensit pf the air gpassing thruethe; carburetor. ..-Therefore oanincrease-li-n density vcausesan increasesin the -.;-q-u antity=of-fuelsfiowing thrutthe carburetor; .It is :believed to .be.-.readily apparentif :it. is/ desired =As..previously.-described, the relief-.va1ve 265 tal.proportionthe mass of -fuel to-the mass :of-air, maintainsa substantially. constant pressure at ,t wquantjtyv lof ,fuel mu5t-;"be".;'j.ncrea,Sed 3,5 1,115

i thecoutletof pump.25.| The gear. pump..253 may be used to boost this pressureand increase vthe .f-uelsupply above .the. .valuedeter-minedby the discharge ,pressure. .ofpump I. I, or ...the gear 2 pump .12 5.3..fmay .be. utilized. .as a .fluid' motor .to ildriveltheelectrical motorI254as a generator; in

which case-ithewpump253-bucks-the discharge 7 ...pressure or pump 25L .andrreduces the fuel density of thei-aindncreases. -zThe resistance .2 l1 reflects,suchFan-increase.

v.'lhe-.-resistance -of-.-;aelement:c2 L3 varies. directly was -.t he load-:on the-.enginenas measured-by the .drop. inapressureeacross thez throttle, 21 5 :as; previously .described. :The: resistance element z |.3:-.is -..connected inla .branchof .the bridge circuitadiai cent. the branches. containing .--elements .2 H- and S pp Whether thelp-ump 253-0pePateS to boost ;.221; and. therefore. itseffection..thmunhalancev of .or..b.uck the dischargepressure of pump 25-! is determined 2 by .the ..polarity ,(or phase, if alternating current) of..the currentsupplied. to motor '254 byqamplifier1260. The...magnitude of the .the .bridge circuitds-.opposite; to. that of elements 1 2 l |.-and.22.l.. .Thatis an-increasewin resistance of element. 2 I 3 causesaan; increase in. the quantity of fuel flowing thru the carburetor;.-Since-.the

Lboosting. or. buckingueffectlis .determinedby the. II-resistance. of element 2 Hues; directly the magnitude. of thatcurrent. 1

.. load on the eng-ine,=.-it.rmayabe-seen that-.theefiect In-'.the.present .instance,-it.isz.desired to use the (output. potential. of amplifier 260asameasure of directly 3 junction, of the .engjne loa d; .q l y--0 1 pp ie engine, as The. resistance238,.-which ismanual-lywariable, described... hereinafter .in. connection -:-.with Figure may be .z.utilized...a .,a seontr of "the ;fuel to -air .4. -Furthermore,:.as alsodescribed insconnec io ratio. 13y?increasing-sthen-resistance.rofi.element W th t is s a p r 01117- ..238.,lthe.iuelstoaair ratio is. i ncreased,;-and by .deru e---' y ..creasing its -resistancenthezfuel .to-air. ratio is venientlybet-utilized. in anindicating-meter. r a d M For these r aSQ f- 'D r tovchoosevthe Spring .The. variablegresistances2403s connected in the :15?! so;that-the.discharge-p ess re .-D l ..-bridge,.circuit-.-intsuchra manner.-.that..ifcontact 1S efiective w en:pu p 3 isop to 230 is moved to the right, therresistance'.ofwthe supply-a qua ityof-iuel thrurestrictions-255and .branch of z-the bridgeccircuit.-containing element .292 .sufiicient to operatethe engine atits:-maxi- .ZZ Irisincreased-andtheresistance of theibranch mum outp he g r-1 91 p -jo containing element 213:.is-deoreased: =-.Therefore, ated to buckv the discha e "pressure-0fp mp 2 5 such-a imovement'oficontactz 230: causesea :decrease W'hen he c ae cc -ma m the ,.in..the..quantity orifuellfiowingwto .the---.engine. energization of. motor. 25.4.must be at a maximum, .Such :a. movement; fp nt t zm i a d b an and the fuelffiow isthen at a minimum- In-order .inorease .inothe pressure drop across restriction ito secure such -.a mode- 0fope a -0f he l 5,355. '.Therefore,-itc-may-.= be.seemthat-- resistance ephfier, the various ,resistance elements 'in the 240 is varied to change the balance of th xbridge ..bridge circuitv arenchosen so. thatthenbridge. is ..'circuit,.in.-accordaneemith .the: quantity offuel always unbalancedarid thedegree ofunbalance v.fiowing .-to -.the-. carburetor. The eresista-nce "240 7 decreases with increasing 'demandifor fuel flow. ..insures.that-uponzachange-inithesrunbalanceof 'The'magnitude of the signal appliedutorthe amwool-the bridge circuit, the.resultingr change in the fuel ,.p1ifier. input terminals, andhencerthev amplifier inflowis:proportionalrto:theachange-otair flow-or J outputthenvary inversely astheiueliflow. mother controlling ,conditionsa-which initiated the 'Aspreviously, describd,. resistance element 2 21 changed balaneeiconditionqo .the-gbridge circuit. varies inverselyasIthequantity.ofeairflowingthru .The,restrictions:255rand5292rarevpreferabl$ so .ip ssagezfl l. Therefo'renwh n thequantityof aire proportioned that whemmesirmnonzaaz ismlosed "flowing is low, asunder. idling. conditions,; the zby-rvalye-e294,@thenquantity Ofrfuel:passing .thru resistance of element'iflis (high. A If. the polarity ..restrictio1r255-alone. whempumpi-253eisinotoperof battery 234'is chosen as indicated-by .thelegend 1 -ated to resist.thei iueliflownisrthezquantity'offuel in the drawing,. then.whenitheresistance.of ele- .necessarytoisupplmthegengineiat.75.%."ofits rated ment'22-7. is high, 'the.ou,tput terminal-236 is negaei'm loadJ -Thereformfitmay1be;seenithatupon iailure 1 tivewith respectJto output. terminal 135.: The .of. the power;supplyfihearesulting deen-ergization bridgecircuit is vtherefore. normally unbalanced 1 of solenoid-.Zlflccaus'es yaiveafltttor.close,:'th-ereby ma a direction such that. output terminal 235. is :setting the."fuelasupplyaatatvaluei to produce positive --.with respect .to :output-terminalefifi. As 7 ref thematedeengineoutput V :..the..;quantitysofrair fiowingn-thruithe .earburetor 75 LIfZit WBI'BTHIOt .idesiredntornhave the e phfl .ofrelement .2 I this to.-.vary athe fuel to fair ratio output unidirectional and varying in accordance with fuel flow, the bridge circuit might be arranged to be balanced at some intermediate value of fuel flow. In such an arrangement, the discharge pressure of pump 25! is chosen so as to produce the value of fuel flow at which the bridge is balanced. Then upon an increase in demand for fuel flow, the bridge is unbalanced in a sense so that motor 254 operates pump 253 to boost the fuel flow. Upon a decrease in the demand for fuel flow, on the other hand, the bridge is unbalanced in the opposite sense, 50 that motor 254 is driven as a generator by pump 253 acting as a fluid motor, and the fuel flow is thereby decreased.

In such an arrangement, the relief valve 265 may be designed to regulate the discharge pressure of pump 251 so that, when pump 253 is not operating, the quantity of fuel supplied to the engine is sufficient to operate the engine at 75%, for example, of its rated load. Then upon failure of the power supply for motor 254, the engine would automatically receive sufficient fuel for 75% of its rated load. This arrangement avoids the necessity for using the restriction'292 and the solenoid operated valve 264 controlling it.

Figure 4 There is illustrated in Figure 4 an indicator which is adaptable for use with the fuel supply system of Figure 2 to indicate selectively any of four engine conditions, namely l) the quantity of fuel flowing to the engine, (2) the fuel to air ratio, (3) the horse power output of the engine, (4) the brake mean effective pressure of the engine.

In Figure 4 there is illustrated a galvanometcr 326 having a pointer 32| which cooperates with four scales 322, 324, 326 and 328. The scale 322 is calibrated in terms of brake mean effective pressure, the scale 324 is calibrated in terms of horse power, the scale 326 is calibrated in terms of fuel to air ratio and scale 328 is calibrated in terms of fuel flow.

The galvanometer 320 is provided witha pair of terminals 336 and 332 to which any one of four electrical circuits may be connected, as determined by the position of a selector switch generally indicated at 334. The selector switch 334 includes a knob 336 for operating a contact bar 338 to any one of four circuit closing positions and a pointer 346 to indicate which of the four engine conditions the galvanometer 326 will read when the selector switch 334 is in each of its four positions.

When the selector switch 334 is in the extreme left position of the four positions shown in the drawing, the galvanometer circuit may be traced from galvanometer terminal 336 thru a conductor 346, amplifier output terminals 263 and 264 of an amplifier which may be the amplifier 266 of Figure 2, a conductor 342, a stationary contact 344, contact bar 333, a stationary contact 346, a conductor 341, a fixed resistance 348 and a conductor 352 to terminal 332 of galvanometer 326. As described in connection with Figure 2, the output voltage of amplifier 266 is inversely proportional to the quantity of fuel flowing to the engine. Therefore, when the circuit just traced is completed, the pointer 321 will be adjacent the upper end of its associated scales when the fuel flow is low, and near the left end of its scales when the fuel flow is high,

The scale 323 may be provided with suitable colored legends as indicated in the drawing. For

example, a green legend may be used to indicate that the fuel flow is at a median value suitable for cruising, a yellow legend may be used to indicate a fuel flow equal to that required for rated engine output, and a red legend may be used to indicate a fuel flow equal to or greater than that required for take-off or maximum power conditions.

When the selector switch 334 is operated to the position shown in full lines in the drawing, the circuit including the galvanometer 326 may be traced from galvanometer terminal 336 thru con.- ductor 346, output terminals 263 and 264 of amplifier 266, conductor 342,, stationary contact 352, contact bar 336, stationary contact 354, conductor 356, resistance element 3"], conductor 368, resistance element 366 and conductors 358 and 356 to galvanometer terminal 332. In this circuit, the amplifier 266 introduces a potential inversely proportional to the quantity of fuel flowing, while the elements 366 and 3H! introduce a resistance inversely proportional to the mass of air entering the carburetor. Therefore it may be seen that the current fiow thru this curcuit, as measured by the galvanometer is inversely proportional to the ratio of fuel to air in the combustible mixture supplied to the engine.

When the selector switch 334 is in the position next to the right of the full line position shown in the drawing a circuit is completed for the galvanometer which causes it to indicate the horse power output of the engine. This circuit may be traced from galvanometer terminal 336 thru conductors 346 and 366, a battery 362, a conductor 363, a stationary contact 364, a contact bar 336, a stationary contact 366, a conductor 368, resistance 3"], conductor 366, resistance 366, and conductors 353 and 356 to galvanometer terminal 332. Since the potential of battery 362 is substantially constant, the current flow thru this circuit varies inversely as the resistances 366 and 3H). Since the sum of these resistances varies inversely as the mass of air entering the carburetor, it may be seen that the current flow varies directly with the mass of air entering the carburetor. It has been found that the mass of air entering the carburetor may be used, without serious error, as a measure of the horse power output of the engine.

When the selector switch 334 is in the extreme right position shown in the drawing, the galvanometer circuit may be traced from galvanometer terminal 336 thru conductors 346 and 366, battery 362, conductor 363, a generator 316 driven by the engine so that its speed and Voltage output are proportional to the engine speed, a contact 312, contact bar 336, a contact 314, a conductor 316, resistance 3l6, conductor 363, resistance 366, and conductors 358 and 356 to galvanometcr terminal 332. Generator 316 is chosen so that its terminal voltage at maximum speed does not exceed that of battery 362, and it is connected in this circuit, as indicated by the legend in the drawing, so that its polarity opposes that of battery 362. Therefore, the net potential in this circuit varies inversely with the speed of the engine. The resistance in this circuit varies inversely with the mass of air entering the engine. Therefore the current flow thru this circuit is directly proportional to the mass of air entering the engine per revolution. Since the displacement of the engine cylinders is constant, this mass per revolution may be taken as an indication of the brake mean effective pressure in the engine cylinders. I

V Figured- There is' illustratedin Figure another form -of'- electrical control system for a carburetor.

InFigure 5, airentersthecarburetor thru an inlet 4llll-and passes thru a venturi462 and a passage-404 past a throttle'466and a discharge nozzle 468 to an outlet 4lll. A- portion of the air entering the carburetor passes thru impact tubes 4l2 and a vent ring; M4 to the'interior of a casing 4l8; A flexible-bellows 42 is mounted inside casing M8, and the-interior of bellows 426 is connected thru a passage-422 to'the throat of venutri 462-. Therefore, it maybe seen that bellows 426 contracts when. the pressure 'difierential between the'inlet wit-and the throat of venturi 462 increases, and expands when that pressure difierential decreases;

Fuel enters'the carburetor'of Figure 5 from'a,

-fuel-pumpor othersource of fuel under pressure {not-shown) and passes thru a conduit 422, a metering restriction-424, a conduit 426, and past avalve 428' to the nozzle 468. 'The metering restriction 424, althorshown as a single restriction for-purposesof convenience, maybe replaced by a more conventional 'jet system including several restrictions. The conduit 422 upstream from restriction-424- is connected'thru a conduit 436 to the interior of a casing 432. A bellows 434 is mounted inside casing 432; and its interior isconnected thru aconduit 436 to the conduit 4'26 downstream from the restriction 424. The pressure difierential across'restriction 424 controls the expansion and' contraction of bellows 434, .causing the bellows to contract when the pressure differential increases and to. expand when the pressure difierential decreases. This pressure .diiferential-may be utilized'as a measure of' the quantity of fuel flowing thru restriction424,

The free end ofbellows'426is attached to a link-436whose other endis attached to an arm 44 6 pivotally mounted at 442 and" carrying at its opposite end aninsulatedcontact 444. The contact 444 cooperates with a slidewireresistance 446insulatinglymounted on-a plate 448 which isalsopivotally movable about the point 442. The-free end of bellows-434 =is connected by link 456 to the plate 448-.

From the foregoing it may be seen that an increase in the air flowthru'the"passage 464," as

measured by the pressure differential acting on bellows-420 -causes an upward movement of link 43B and a counterclockwise rotation of arm 440 about pivot442, moving contact 444 upwardly along resistance 446; Also, an'increase in the fuel flowingthru restriction 424 causes bellows 434 to collapse moving link 456 downwardly and rotating plate448" counterclockwise about pivot 4'427'a'nd. causing'anupward movement of resisteoance 446 under contact 444.

When the air flow is proportional to the fuel flow, the contact 444 lies atxthe center of resistance 446, andwhen the air How is proportionatelyjgreater than'the fuel. flow, contact 444 is above the center of'resistance :446; Similarly, whenlthe "fuel flow isaproportionately greaterthan air flow, the contact 44-4 is below the resistance 446'. The resistance 446'is connected bymeans of conductors 452 and 454' in parallel with a and 456. The twol:resistances 446 and'456and V 'the' battery 456 form abridge circuit of which the'-'conductors 452 and 454-may be termed-the 16 "are: connected :by'conductors: 4601' 2.1162462 respec tively to the input terminals .of an=amplifi'er 464'. The output terminals" of amplifier 464-"are. con nected to a reversible electric.motor 466; which drives thrua gear train (not shown) a shaft 468 whichnis provided with an internallythreaded recess at one end to receive an'externally'thread ed valve stem 4102 The Valve stem 4lfl'is' held against rotation bytmeans" of a key'412? andzis connected to the "valve 428 whichcontrols the flow of fuel thru conduit426: The construction 'issuch that uponarotation' of motor 466; the valve 428 is moved longitudinally in'a direction depending upon the direction of rotation of motor 466. Motor 466 rotates in a direction determined by the polarity of the'amplifier output, which is in turn determined by the polarity of the'ampli fier input. The amplifier input polarity depends upon theposition of contact 444 with respectto the midpoint of resistance 446-;

The arrangement should'be such thatfiwhen contact 444 is above the center of resistance 446, indicating that the-air flow is proportionately greater than the fuel flow, themotor 466 operates valve 428 in an opening direction thereby in creasing the fuel-flow: Likewise; when contact 444 is below the center of resistance 446, motor 466 operates valve 428 'in a closing direction.

While I have shown no means for compensating the system of Figure'5- for variationsintair density, it will be readily understood thatsuitable means may be provided: For example; one portion of resistance-4'56 could' be varied in the same ,manner that resistance.- 42 of 'Figure: 1v is varied.

While I have illustrated a direct current bridge circuit, it should'be readily: apparent that'a'lternating current could be used with equal: facility if corresponding changes'were' made in'the amplic-fier 464 and motor 466*.

While I have shown anddescribed'certain preferred embodiments of the principles of" my invention, other modifications thereof will readily occur to those skilled in the art, and I therefore intend my invention to be limited only by the appended claims;

I claim as my invention:

1. In a carburetor for an internal combustion engine;-in combination, a first conduit for air flowing thru said carburetor to said engine, a second conduit for fuel flowing thru said car- ,buretor to said engine, an electrical circuit,

means to vary an electrical quantity in said'circuit as a function of the quantity of air flowing thru said first conduit, means operative as an incident to a change in the intake manifold pressure of said'enginefor additionally varying said quantity, and means responsive to said electrical quantity for controlling the flow of fuel thru said second conduit;

2. In a carburetor for an internal combustion engine; in combination, a conduit for fuel flowing thru" said carburetor to: said engine, two: valves connected in series insaid conduit for controlling the flow of fuel therethru;firstxelectrical means 'ior'operatingoneiof'said'valves in a flow increasing direction upon'an increase in the energization ofsaid electrical means, secondelectrical means for operating the'rother of said valves in a flow decreasing direction uponan increase'in the energization of said second;electricalmeans, a source of electrical energy, means for controlling the energization of atleast one or said'electrica'l 1 means from saidsdurce in"accordance with a 17 by said engine, and means corinecting 'botnof said electrical means'to "said sour'ce so that a variation in the'p'otential of said source causes operation'of said valves in opposite senses s'o that the fuel flow is not affectedthereby.

3. In a carburetor for an internal combustion engine, in combination, a first conduit for air flowing thru said carburetor to saidengine, a second conduit for fuelflowing -thru said car buretor to said first conduit; a metering restriction in said secondconduit,-" a first valvein said second conduit upstream i-rorh -said'restri'ction, first electrical means- -foroperating said first valve, a source of electrical energy','- means 'for controlling the energization of said first'elec trical means from said source in accordance with the quantity of air flowing thru saidfirst conduit, a second valve in said second conduit down stream from said restriction for regulating the pressure therein, said second valve -being' -sub.-' stantially balanced against ch'anges'in outlet pressure so that its position is notaffectediby. the pressure in said first-conduit; second electrical means for operating said second valve, andmeans connecting said second electrical 'means to said source;- said first andsec'ond electricali means being I effective to ope-rate their-respective values in opposite senses-upon a variation-in the-=poten;- tial of said source -so-tl=1at -the fuel flow is not affected thereby.

4. In a-fuel sup-ply system-for aninternalwcombust-ion engine,- in combination,-' a conduitwfior fuel flowing to said engine,--a. pump in said' conduit for supplying fuel to saidengine pmeans-for regulating theoutput-of said-pump. so 'asto maintain a substantially constant diseharge pres;- sure, a fluid-motor-in saidconduitinseries-[with said pump, said motor-being'driven in one-direction by fuel flowing from saidpur iip toward said engine, an electrical-motor '-for applying torque 0 to said fluidmotor acting in the-opposite direction so as -'to 'r'educethe' quantity of f uer discharged thru said fluid motor'loy 'said pump', and electrical means responsive to the quantityozf air flowingto saidengine tor-combustion purposes for controlling said rnotor; a i

5. Electrical flowcontrolling rneansgcompris ing in -combination,-=a fluid-eonduit'g two' calves connected in series in saidc'ondu-it for controlling the flow of fluidtheretlaz-u,"firstelectrical means-for operating-one of said valves in a flow increasing direction uponan increase --in the energization of said'electrical means, second el'ec trical mean-s for operatingthe dther "of said valves in a flow decreasing direction upon an increase in the energizatiomof saidsecond electrical means, a sourceof electrical energy, means for controlling the-energizationof one'of said electrical means from said-sourcein accordance with a condition indicative of the need for operation of said flow controlling meansand means connecting both of said-electrical means to said source so that a variation in the potential of said source causes operation of said-valves in opposite senses so that the fluid fiow is not affected thereby.-

6. In a carburetor for an internal'combust'ion engine, in combination; a conduit for fuel flowing thru' said carburetor'to saidengine) avalve in said conduit for controlling the flow of fuel therethru, electrical meansfor operating said valve in a flow decreasing direction upon an increase in the energizationthereof, an-elect-rical circuit including an impedance for energizing said electrical means,- and means-for shunting 18 Saar impedance to reduce the 'flow 'of fuel to said engine.

7. in a carburetor for an-imemarcomttsnon engine,- in combination, a conduit for? fuelflowih'g thru said carburetor to said -engi ne, two valves connectedin series in said conduit-for controlhug the flow of f-uel therethru} firstielectrical means for operating one'of said valvcsin anew increasing directionupon an increase-in the' energization or said electricalmeans; second ele'c tric'a-l means-for operating-the dth'er of said valves in a flow decreasing d-irection-upon-an increase in the energiZa-1on- -of' sai'd second-electrical mean-s a source of electrical energyineans-ror controlling the'ehergiatie' at one or; saideiectriearmeans from said source in accordancewith a Condition'ihdicatil/e of the quantity of f-ul needed by said engine,- means connecting" both of said electrical rr'ieans to said source so that a variation in the potential- 01 'saidsource 'causes operation of said valves in opposite-senses so that the-fuel fiOiViS' notfalffte d' thereby, mea'lis'for increasin g' the' e'nergization of said first electrical meansto -prev-icle an" increased fuelsupply; and second means fm nereasi-hg the energization of saidsecond electr'ieal means-'to reduce the flow of fuel' to saidehgine'i 8. In a fuel supply system for an internal -coinbustion'engine; a conduit-for fuel flowin g tb said engine; ane'ngin'e' driven pump in said cond-iii t for" delivering fuel to -saidengine undenpres sure; "a' fluid motor in said"conduit rceiving iuel from "s aid pump, "electrical means for applying a variable load to said fluid motor to contro;l;'-the flowbf fuel thruj said conduitfmeansresponsive to the quantity of air flowing to smash-gins for combustion purposes 'fo'r"c'ontrolling the entergizatiori'of said electrical means',"and'means for regu a n h s'c ge' p s ui' flb' s d'pi mlp' maintain said discharge pressure at a" substantiallj', co stant va1u'e','said'pump andsaid re ulating meanscoo eratmg "to maintain a predetermined su ply of fuel to, said engine upond'eener'gizdtidn o'f saidel'ectri "al' means.

9 In a fuel u ly ystem for aninterna combustion-enginefa conduit for'ruei flowing to engine-a purnp driven y saidengine negated in said "conduit fordeliv'rin'g fu -rosaid engine under pressure, means for 're 'ulatin discharge pressure of said pump'to, mai talri'sa discharge pressureat a substa'fi'ti'allyhonstrjit value sufiicient to maintain a maximum sup 13; of fuel, a fluid motor in sai "conuuirr ce vigg i-uel from said pump, electrical means for' appjly ingya variable-load to said fluid motorto control the-flow of me] thru said condmt,'vame"meass for restrlctingthe flow thru saidconduit down stream irorn said-fluid motormeans biasing said valve means to a flow'restrictingvposition, second electrical means effective-whenenergised to one are said valve" mean t a l w ermi n 1i tion aga nst said a in m ans; a: S r e Q fle trical energy :i'or both saidelectrical means, said biasing means-being effective -upen -failur of said-source to operate-said valve mean-s Q its flow-restricting positionand thereby to limit-the supply'of fuel to a value suflicient-to opelyatesaid engine at a predetermined proportion of its rated load;

10. In. fuelsupply "system' 'for an "internal combustion engine; a first conduit forair mowing to said engine for combustion purposes, means associated with said conduit for producingtwo unequal pressures: Whose "difference is a measure '19 of the quantity of air flowing therethru, a second conduit for fuel flowing to said engine, a metering; restriction in-said second conduit, means for controlling the pressure differential across said restriction to control the fuel flow 'thru said conduit, a first pair of expansible chambers separated by a first movable wall, means for conveying said two unequal pressures to said chambers so that said wall is positioned in accordance with the difference of said two pressures, a second pair of expansible chambers separated by a second movable wall, means for conveying to said second pair of chambers the pressure difierential'across said restriction so that said second wall is positioned in accordance with said differential, a slidewire resistance member, a contact member movable along said resistance member, means connecting each of said members with one of said walls for movement therewith, and electrical means responsive to the relative positions of said members for operating said pressure differential controlling means.

V 11. In a fuel supply system for an internal combustion engine, a conduit for fuel flowing to said engine, means for producing an electrical potential varying as the quantity of fuel required by said engine, means responsive to said potential for controlling the flow of fuel thru said conduit, an electrical meter, a fixed resistance, and an electrical circuit including said meter, said potential producing means and said fixed resistance in series so that said meter indicates the quantity of fuel flowing in said conduit.

12. In a fuel supply system for an internal combustion engine, a first conduit for air flowing to said engine for combustion purposes, a second conduit for fuel flowing to said engine, pump means in said second conduit having a constant discharge pressure and tending to cause a constant fuel flow thru said second conduit, means for producing an electrical potential varying in'- versely as the quantity of fuel required by said engine, electrical means responsive to said potential for reducing the flow of fuel thru said second conduit in accordance with the magnitude of said potential, an electrical meter, a fixed resistance, and an electrical circuit including said meter, said potential producing means and said fixed resistance in series so that said meter indicates the quantity of fuel flowing in said second conduit, said pump means being efiective on failure of said electrical means to produce a predetermined flow of fuel in said conduit.

13. In a fuel supply system for an internal combustion engine, a first conduit for air flowing to said engine for combustion purposes, a second conduit for fuel flowing to said engine, means for producing'an electrical potential varying as the quantity of fuel required by said engine, an electrical meter, a fixed resistance, resistance means variable in accordance with the quantity of air flowing thru said first conduit, and switch means for selectively establishing either a first circuit including said meter, said potential producing means and said fixed resistance in series so that said meter indicates the quantity of fuel flowing in said second conduit, or a second circuit including said meter, said potential producing means and said variable resistance means in series so that said meter indicates the ratio of fuel to air supplied to said engine.

14. In a fuel supply system for an internal combustion engine, a first conduit for air flow- 2o ins 'to'said engine for combustion purposes,-a second conduitfor fuel flowing to said engine, means for producing an electrical potential var-y-' I ing as the-quantity-of fuel required by said engine, an electrical meter, a fixed resistance, resistance means variable in accordance with the quantity of air flowing thru said first conduit, a source of substantiall constant electromotive force, and switch means for selectively establishing either a first circuit including said meter, said potential producing means and said fixed resistance in'series so that said meter indicates the quantity of fuel flowing in said second conduit; a second circuit including said meter, said potential producing means and said variable resistance means in series so that said meter indicates the ratio of fuel to air supplied to said engine, or a third circuit including said meter, said constant E. M. F. source, and said variable resistance means in series so that said meter indicates the power output of said engine;

15. In a fuel supply system for an internal combustion engine, a first conduit for air flowing to said engine for combustion purposes, a second conduit .for fuel flowing to said. engine, means for producing an electrical potential varying as the quantity of fuel required by said engine, an electrical meter, a fixed resistance, resistance means variable in accordance with the quantity of air flowing thru said-first conduit, a source of substantially constant electromotive force, means for generating an electromotive force proportional to the speed of said engine, and switch means for selectively establishing either a first circuit including said meter, said potential producing means and said fixed resistance in series 'so that said meter indicates the quantity of fuel flowing in said second conduit; asecond circuitincluding said meter, said potentialproducing means and said variable resistance means in series so that said meter indicates the ratio of fuel to air supplied to said engine; a third circuit including said meter, said constant E. M. F. source, and said variable resistance means in series so that said meter indicates the power output of said engine, or a fourth circuit including said meter, said generating means and said variable resistance means in series so that said meter indicates the brake mean effective pressure in said engine.

16. In a fuel supply system for an internal combustion engine, a first conduit for air flowing to said engine for combustion purposes, an electrical meter, resistance means variable in accordance with the quantity of air flowing thru said first conduit, a source of substantially constant electromotive force, means for generating an electromotive forceproportional to the speed of said engine, and switch means for selectively establishing either'a first circuit including said meter, said constant E. M. F. source, and said variable resistance means in series so that said meter indicates the power output of said engine, or .a second circuit including said meter, said generating means and said variable resistance means in series so that said meter indicates the brake mean eifective pressure in said engine.

17. In a fuel supply system for an internal combustion engine, a first conduit for air flowing 70 tosaid engine for combustion purposes, a second conduit for fuelflowing to said engine, means for producing an electrical potential varying inversely as the quantity. of fuel required by said engine, means responsive to said potential for controlling the flow of fuel thru said second conduit, an electrical meter, a fixed resistance, resistance means variable inversely in accordance with the quantity of air flowing thru said first conduit, a source of substantially constant electromotive force, means for generating an electromotive force less than said constant force and proportional to the speed of said engine, and switch means for selectively establishing either a first circuit including said meter, said potential producing means and said fixed resistance in series so that said meter indicates the quantity of fuel flowing in said second conduit; a second circuit including said meter, said potential producing means and said variable resistance means in series so that said meter indicates the ratio of fuel to air supplied to said engine; a third circuit including said meter, said constant E. M. F. source, and said variable resistance means in series so that said meter indicates the power output of said engine, or a fourth circuit including said constant E. M. F. source and said generating means in series opposition, and said meter and said variable resistance means in series therewith so that said meter indicates the brake mean effective pressure in said engine.

18. In a fuel supply system for an internal combustion engine, a first conduit for air flowing to said engine for combustion purposes, a second conduit for fuel flowing to said engine, means for producing an electrical potential varying inversely as the quantity of fuel required by said engine, an electrical meter, resistance means variable inversely in accordance with the quantity of air flowing thru said first conduit, and an electrical circuit including said meter, said potential producing means and said variableresistance means in series so that said meter indicates the ratio of fuel to air supplied to said engine.

19. In a' fuel supply system for an internal combustion engine, a conduit for air flowing to said engine for combustion purposes, resistance means variable inversely in accordance with the quantity of air flowing thru said first conduit, a source of substantially constant electromotive force, an electrical meter, and an electrical circuit including said meter, said source, and said variable resistance means in series so that'said meter indicates the power output of said engine.

20. In a fuel supply system for an internal combustion engine, a conduit for air flowin to said engine for combustion purposes, resistance ,means variable inversel in accordance with the quantity of air flowing thru said first conduit, means for generating an electromotive force proportional to the speed of said engine, an electrical meter, and an electrical circuit including said generating means, said meter, and said resistance means in series so that said meter indicates the brake mean effective pressure in said engine.

21. In a fuel supply system for an internal combustion engine, a conduit for fuel flowing to said engine, means for producing an electrical potential varying as the quantity of fuel required by said engine, means responsive to said potential for controlling the flow of fuel thru said conduit, an electrical meter, and an electrical circuit including said meter and said potential producing means so that said meter indicates the quantity of fuel flowing in said conduit.

22. In a fuel supply system for an internal combustion engine, a first conduit for air flowing to said engine for combustion purposes, a second conduit for fuel flowing to said engine, pump means in said second. conduit having a constant discharge pressure and tendingto cause a constant fuel flow thru said second conduit, means for producing an. electrical potential varying inversely as thequantity of fuel required by said engine, electrical means responsive to said potential for reducing the flow of fuel thru said second conduit in accordance with the magnitude of said potential, an electrical meter, and an electrical circuit including said meter and said potential producing means so that meter indicates the quantity of fuel flowing in said conduit, said pump means being effective on failure of said electrical means to produce. a predetermined flow of fuel in said conduit.

23. A carburetor for an internal combustion engine, comprising a first conduit for combustion air flowing to said engine, a second conduit for fuel flowing to said engine, an electrical circuit, Venturi means in said first conduit for establishing two unequal pressures whose difference is a measure of the velocity of flow of air therethru, a secondary air conduit in parallel with said Venturi means and having a flow of air induced therethru by the difference of said two pressures, a valve in said secondary conduit, a resistance element connected in said circuit and positioned in said secondary air conduit to be cooled by the flow of air therethru, means responsive to the density of the flowing air for operating said valve so as to vary the resistance of said element as a function of said density, and means responsive to the current flow thru said circuit for controlling the flow of fuel thru said second conduit.

24. In a charge forming device for internal combustion engines,.fuel passage means for supplying fuel to the engine having means therein for setting up a differential of pressures proportional to fuel flow therethrough, air passage means for supplying air to the engine having means therein for setting up a differential of air pressures proportional to air flow therethrough, pressure-electric units having their pressure elements responsive respectively to said differential of air and fuel pressures, and valve means for controlling the fuel flow through said fuel passage means having electro-responsive operating means governed by the electric elements of said units to provide a predetermined fuel air ratio, the electric elements of said pressure-electric units comprising resis-- tance members having a resistance which increases progressively along the length thereof, and said pressure elements each comprising a pressure responsive diaphragm carrying a contact element longitudinally slidable on said resistance.

25. A fuel supply system for aninternal combustion engine, comprising a conduit for fuel flowing to said engine, a pump in said conduit for supplying fuel to said engine, means for regulating the output of said pump so as to maintain a substantiallyconstant discharge pressure, a fluid motor in said conduit in series with said pump, said motor being driven in one direction by fuel flowing toward said engine, an electrical motor for applying to said fluid motor a torque acting in the opposite direction so as to reduce the flow of fuel through said fluid motor, and electrical means responsive to a condition indicative of the power output of said engine for controlling said electrical motor.

26. A fuel supply system for an internal combustion engine, comprising a conduit for fuel flowing to said engine, a pump in said conduit for supplying fuel to said engine, means for regulating the output of said pump so as to maintain a subflowing. towardi said: engine; eiecw'tmah motor for: applying to 1 said: fluid motor: aitornue: acting: in

V the: opposite: direction. sm as .toireducetlire: flow: of

fuel; through. said flhidi motor, electrical means responsiireito:amoperatlngtcomiition of said engine; for: controlling, said; electiiira'll motor;

27. fuel: supply system: for: an: irrt'emal: comebustionaengine, comprisingza. conduit. for. oomhus tiom air: flowing to said: engine; aithrottleifor' cone trollin'g; the. flow or air through? said; conduit; a conduit for: fuel: flowing to. said: engine; an electrical circuit, means for varying an electrical quantity in; said circuit. as; a fiunutiom ofcthe. rate of: fiowrof airthrough: said air conduit; means; 1 61+ sponsive to the: pressure in: said air: conduit: at a paint downstream. from saidt throttle: foir varying saidi electrical quantity; andi means; responsive: to said electrical quantity'for'oontrollingsthe fiovw of fuel throughxsaidifuelz conduit 28:. 'A! fuel supply; system. for an: imenna l' comibustiom engine, comprisingz a; conduit-i for com-.- bustion: air: flowing to said. engine a. conduit for fuel; flowing to: said engine, an: electrical circuit, first means for varying an electrical quantity in said circuitriir accordance With-.therate of flow: of air through; said: air conduit; second means for varying said ielectricaliquairtityimaccordancewith the: density of the: air. in: said?- air conduit; third means: for varying saidf electrical? quantity i'rr awoordancewithithe pressure-imthedntake manifold of said engine, fourth meansfon varying said electrical; quantityrin" accordance with. the position: of a' manuallymoyable. controlimenrbeie fifiili': means for varying; said: electrical; quantity in: accordance wit-hzthe; rate of. flow-of fuelstln'ouglrsaidzfuel conduit, and means; responsive: to: said? electrical quantity for controlling-the? flow of the]; through said fuelv conduit.

29;. A fuel: supply: system: for: am internal com bust-ion engine, comprising aiconduitifon'combustion air flowing'to'said engineiaxconfiuit; for flowing tosaidr engine; an electrical. circuiu. means responsive to the magnitude: of: a; untlirectibnal electrical quantity: in said forcontrolling the:- flow' offuel. through said; fuel: first means. forvarying; the magnitude: said 'eieetrica-l quantity in! accordancawitlr rateotflow on air through. said: air conduit an'di efiectiive to vary said. magnitude; in as fuel: flow: increasing sense: in response to am increase: thmnaite. of; air fiow,, and second; means for varying: the: magn-l tude of sa-idelectnical.qnantity imaccondance with thevolume-offuel'flowing through: said: fuel cenduit-per unit time and. efiective; ta vamp saidunagnitude in a. fuel flow decreasing sensedmresponse team increase imtherate of. fiomof: fuelz:

30. In. a charge forming, device for: internal combustion engines, fuelpassageameansrfiirsups plying fuel to' the: engine,- havingi orifice means 2 9 therein: for setting up: a: differential: of; fuel: prose sures, air: passage".- means for supplying air to; the engine:- liavingf a venturi therein for: setting up a difierentialiof-t pressures" proportional. to air flow. therethroughz, valve means for: controlling, the fuel flow to said. orifice means, e1c'tro-responsive means for operating. said valve means; pressureelectric. units 1 having electric elements".controllingthev energi'zation: of said. electro-responsiile means and having. their pressure elements responsive to pressure changes: an'di'to temperature changes' inthe air in said venturi to said difierential of fuel pressures and; to. said diverentiali of air: pressures:

31'. 'In a charge forming device foraninternal combustion engine; fuel metering means forsetting up a. differential of fuel pressures, air metering means for'setting up a differential" of air pressures, valvem'eans for controllingthefiow offuelto said fuel metering means; an electric circuit, pressure-electric means having their electricelements connected insaid circuit and havingtheir pressure elements controlled. by said fuel and" air differential pressures and by' the'temperature of the charging air, and electro-responsive means for actuating said valve means energized. upon changes in temperatureand pressure afiectingthe electric elements'ofjsaid pressure-electric means LEIGH'EQN LEE, II;

REFERENCES CITED The following references. are; oh record: in the file of thispatent:

H UNITED STATES" PATENTS Number Name 7 Date 1,437,626 Wilson Dec; 5,. 1922 1,826,762; Franklin: Oct..1;3;.1931 1,849,335 Schmidt Mar. 15,1932 2,004,869 Hogg. June-11,1935 2,224,472: Chandler .Dec2.1 0; 1940 2,228,000 Chandler J'an...7:, 1.941 2,250,932 Kittler July'29-,;194Jz 2;28I,4-1I Campbell 1 Apr..28 1942 [2,295,656 Hersey et a1; Sept..1 5,.1 942 2,303,998 Thompson: Dec; 1, 1942 2,305,912. Holley, Jr; Dec. 2 2,= 19.42 2,310,984 Mock et a1: Feb. 16 1943 2,330,650 Weiche Sept. '28; 1943 2,341,257 Wunsch Feb. 8, 1944 2,348,113 Davis M3 2", 1944 2,372,766 Colvin et a1 Apr..3', 1945 2,395,648 Teichert Feb; 26,1946

FOREIGN PATENTS.

Number Country- Date- 442,497 Great Britain May 3, 1934 523,895 Great Brita-in July 25 1940 543,260 Great Britain Feb; 17, 1942 549,249 Great Britain- Nov-: 1-2, 1942 France Dec.120;'1 937

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