US2540735A

US2540735A - Carburetor

Info

Publication number: US2540735A
Application number: US602332A
Authority: US
Inventors: Scott F Hunt
Original assignee: Niles Bement Pond Co
Current assignee: Niles Bement Pond Co
Priority date: 1945-06-29
Filing date: 1945-06-29
Publication date: 1951-02-06
Anticipated expiration: 1968-02-06

Description

Feb. 6, 1951 S. F.. HUNT CARBURETOR Filed June 29, 1945 AGENT Patented Feb. 6, 1951 GARBURETOR Scott F. Hunt, Meriden, Conn., assignor, by mesne assignments, to Niles-Bement-Pond Company, West Hartford, Conn., a corporation of New Jersey Application June 29, 1945, Serial No. 602,332

i 11 Claims.

, This invention relates to a carburetor for an internal combustion engine and particularly to means for operating such a carburetor so as to provide improved acceleration characteristics oi the engine.

It has previously been proposed to provide, in a carburetor for an internal combustion engine, a device responsive to the air pressure in the air induction system at a point downstream from the throttle and effective upon an increase in such pressure, such as accompanies a sudden opening movement 01. the throttle, to inject into the air stream an additional supply of fuel` so as to rapidly accelerate the engine. Examples of such devices are shown` and described in my :3o-pending application for Carburetors, Seria-1 No. 491,096, led June 17, 1943 and matured into Patent No. 2,442,046, issued May 25, 1948. b

With devices dependent for their action upon variations in air pressure there is an unavoidable small time lag between the movement of the vtl'irotte and the resultant increased or decreased pressure, and there is a further small time las unavoidably incident to the transmission of the increased or decreased pressure to the devices which are used to deliver increased.V ordecreased amounts ofA fuel. Furthermore, the variations in air pressure are not necessarily exactly commensurate with the rate of movement of the throttle and there may be indeterminate variations in the increased or decreased pressures. The principal object of the present invention is to avoid the before-mentioned and other objections which are sometimes encountered when entire dependence is placed on changes in air pressure, without however sacrificing the advantages incident to prior mechanisms. principal object of' the invention is attained by providing a means which is mechanically connected to operate in unison with the throttle and which serves in conjunction with associated elements to provide a fuel flow thru a secondary fuel conduit, or fuel iiow at an. increased or decreased rate thru the main fuel conduit, the said means being operable only' upon sudden movementv of, the throttle'. The said means oril accountv of its mechanical' connection with the throttle is free from any time lag and is entirely positive and determinate in its action.

A still furti er object of the invention is to provide a single means operable with the throttle, whether mechanically connected therewith or otherwise, and serving upon sudden opening movement of the throttle to provide a fuel ow thru a secondary fuel Conduit Simi,J 11G i156 llbvde' The said` 2 increased fuel flow thru the main fuel conduit, thel said means preferably also serving upon sudden closing movement of the throttle to provide decreased fuel flow thru the main` fuel conduit.

A further object of the invention is to provide certain improved features of. construction and arrangement of parts which serve toV effectively enable the throttle operated device to accomplish the desired results.

Other objects and advantages` of the present invention will become apparent from a consideration of the appended specification, claims and drawing which shows a somewhat diagrammatic illustration of an internal combustion eng-ine carburetor embodying the principles of my inven tion.

Referring to the drawing', there is shown a body lil of a carburetor for an aircraft type internal combustion engine. Air enters. the curburetor body l0 at an inlet l2 andA flows` thruA a Venturi restriction I4 and a passage l5, past a throttle I6 and a fuel discharge nozzle I3 to'an. outlet 2D. A supercharger may be provided between the outr let 20 and the intake manifold of the engine. In

certain cases the supercharger may be upstream from the inlet l2, or two superchargers may be used, one in each place.

The Venturi restriction I4 produces a pressure differential between the inlet l2 and the throat of the restriction which varies substantially in accordance with` the square of the velocity of the air passing thru the restriction. Since the cross-sectional area of the venturi` is constant,

= this pressure differential may be taken as a measure of the volume of air flowing thrul the 4passage per unit time. In4 order to obtain a pressure dilierentlal varying asa function of the mass or air per unit time flowing thru the venturi i4', the pressure differential between the entrance l2 and the throat of venturi I4 is utilized to create an air flow thru a Secondary air passage extending from. entrance l2 to the throat of venturi M. A. plurality of impact tubes 22 is provided, whose open ends project into the entrance |12- to receivev the impact of the entering air. The secondary air passage may be traced from entrance l2, thru tubes 22, a passage 2A interconnectingV the impact tubes, a conduit 26, a conduit having a restriction at 28, a conduit 39, a restriction controlledY by a valve 32, a chamber 34 and a passage 33 in the body ID to the throat ofthe venturi Il. The conduits 26 and 39 are The fuel enters'the carburetor from a fuel pump or other source of fuel under superatmospheric pressure. It flows thru a conduitV 44, Va valve 46 ina pressure regulator generally indicated at 48, a conduit 50, a mixture control unit generally indicated at 52, a jet system 54, past an idle valve 56, thru a conduit 58, a valve 60 in a second pressure regulator 62, and a conduit 64 to the fuel,

discharge nozzle I8, These several conduits and connections will be referred to collectively as the "main fuel conduit.

The pressure regulator 48 includes a diaphragm 66 separating a pair of

expansible chambers

68 and 70 and connected at its center to the Valve 46. A spring `i2 biases the vvalve 46 toward open position. A restriction 'i4 connects the chambers 68 and 10. The position of valve 46 is determined by the balance between the pressure in chamber 'l0 acting on the diaphragm 66 in the valve closing direction and the spring l2 plus the pressure in chamber 68 acting on the diaphragm 66 in the valve opening direction. If the balance between these forces isf upset, the diaphragm 66 and valve 46 move until the balance is restored.

The mixture control unit 52 includes a disc valve 76 xed on a shaft 18. The disc valve I6 controls the now of fuel thru ports opening into

conduits

80 and 82 which lead into the jet system 54. When the disc 16 is in the position illustrated in full lines in the drawing, fuel can flow to the jet system only thru the conduit 80. This full line position of the disc valve 16 is known as the lean position of the mixture control 52. When the disc valve '|6'is in the dotted line positionshown in the drawing, the fuel can ow thru both the

conduits

80 and 82. The dotted line position of disc .valve 16 is termed the rich position of the mixture control. The disc valve 16 can also be moved to a cutoff position wherein it cuts off the flow thru both

conduits

80 and 82.

The conduit 80 conducts fuel either thru a fixed restriction or jet 84, or thru a restriction 86 controlled by an enrichment Valve 88 biased to closed position by a spring 90. The conduit 82 conducts fuel to a xed restriction 92. Fuel flowing thru the

restrictions

86 and 92 also ows thru another restriction-93 which limits the total

ow thru restrictions

86 and 92. The valve 88 is normally closed, but opens athigh pressure differentials across the jet system to increase the fuel-to-air ratio under heavy load conditions.

The pressure meter 42 has a diaphragm 94 separating the

chamber

38 and 40, this diaphragm being connected with a valve 66. A spring 98 biases the valve 96 for movement in the closing direction. The meter 42 also has a chamber 38 by a diaphragm |02, and a chamber |04 separated from the chamber 40 by a diaphragm |06. The diaphragms |02 and |06 are operably connected with the valve 96. The chamber |04 is connected by a conduit |08 with the cham ber 68 of the pressure regulatorv48, and the downstream side of the valve 96 is connected by a drain conduit with the main air passagev l5. The connection of drain conduit H0 with the main air passage is shown by way of example only. It may alternatively be connected to the fuel tank or to any point having Va relatively low, substantially constant pressure.

The chamber |60 is connected by a conduit ||2 with the conduit 58 at the downstream side ofthe jet device 54. The last-mentioned con- |00 separated from the chamber,

nection is indirect and extends thru devices to be described. The pressure in the chamber |04 is the same as that in chamber 68 of pressure regulator 48, and the pressure in chamber |00y may be the same as that in the fuel line downstream from the jet system. The position of valve 96 is determined by the balance between the differential of the pressures

inthe chambers

38 and 40 plus the spring 98 acting in the valve closing direction and the differential of the pressures in the chambers |04 and |50 act-V on the upstream side of the jet system 54. ForV any givenY constant-cross-sectional area of the fuel passages thru the mixture control device 52 and the jet system 54, the pressure differentialv across them is a measure of the fuel flow thru them. Increased cross-sectional area thru the. mixture control device and the jet system lreduces the pressure inchamber 10, thus changing the balance of pressures on the diaphragm 66 and permitting the valve 46 to move in opening direction and increase the fuel supply. Conversely, decreased cross-sectional area increases the pressure in chamber l0 and causes the valve 4u to move in closing direction.

The valve 46 is further controlled by varyf ing the pressure in the chamber 68 .by means of the pressure meter 42 and devices associated therewith. As already explained, the valve y96 of the pressure meter 30 is positioned in accord.

ance with the balance between two forces, one of which tends to close the valve and varies in accordance with the mass of air entering the carburetor,V and the other of which tends to open the valve and Varies in accordance with the mass of fuel owing thru the carburetor. It will be apparent that increased air ow in the main air conduittends to move the valve 96 in the closing direction, thus increasing the pressure in chamber 68 and moving the valve 46 in the opening direction. The resultant increased fuel iiow increases the pressure differential between the chambers |04 and |00, thus tending to move the valve 96 in the opening direction. These two opposing tendencies establish a balance. Similar, but reversed, results follow from a decreased air flow.

The before-mentioned valve 32 in the secondary air passage constitutes a second restrictiony therein, the first restriction being at 28. It will be clear that closing or partial closing of this valve increases the pressure drop at that point, and correspondingly decreases the pressure drop at the restriction 28. Decrease of the pressure drop at 28decreases the pressure differential on the diaphragm 94 and tends to move the valve 96 in the opening direction, and to thus decrease the fuel ow in the manner4 already de. scribed. y Similarly, movementpof the valve 32` in the opening direction increases thefuel ow. The valve 32 therefore serves as a means for regulating the fuel flow supplementallyto the regulation effected by variations in air velocity. The valve 32 is connected with abellows l I4 filled .with a uid having a substantial coeicient of thermal expansion. Increased temperature or decreased pressure in the chamber- 24 causesA fameuse ithe bellows `to expand and move 'the valve .32 in the closing direction, Cthus decreasingr the rate for iiuel supply. Decreased temperature yor lcreased )pressure in the chamber 34 causes the 'bellows to collapse and move :the valve 132 in .the iopening direction, thus increasing the .rate iof .frue'l supply.

The pressure regulator 62 operates zto main-- tain `a substantially constant pressure .on the downstream side roi the jet system `54 ,and thereby to prevent variations in pressure at the fuel .discharge nozzle 41.8, which `may be due "to oper- :ation sof the throttle or to variations in `engine speed, :from reaching the downstream fside rof the 'jetsystem 'and affecting the fuel flow. The .pressure regulator 562 includes la `.pair yof expat-'lisible .clrxambers |16 and 1| Yi 8 separated yby a vlilfexible diaphragm |20, which is attached fat its center to the valve V6B. A spring |22 lbiases the valve .60 toward closed position. The chamber H8 is `fuel flow directly in accordance with the throttle position at such times. The spring -'98 in the pressure meter 42 acts on valve 96 in the closing direction. When the Vdifferential pressure `actin-g on diaphragm 94 is small, as `under low air now conditions, the `spring S8 becomes the predominating force acting on valve 96. A closing movement of valve S6 causes an increase in ,the fuel flow thru the main fuel line, since the vclosure of valve 96 increases the pressure 'in chamber m4 of pressure meter 42 and thence in chamber 68 of pressure regulator 48. Furthermore, the spring l2 of pressure regulator 48 biases valve 48 Vin an opening .or fuel `low increasing direction.

`The idle valve 56 'is pivotally attached to a Vlever |26, whose opposite end 4is connected by a link |28 to an arm |30 fixed on 'the shaft |32 of throttle I6. The idle valve is normally `wide open when the throttle Ais 'beyond a range of Apositions near its closed position, usually termed the idling range. As the throttle moves into the idling range, thereby decreasing the air new, the idle valve '55 moves toward closed position. At the same time, the

springs

98 and 12 cause operation of valve 4t in an opening direction. The valve 4G is thereby opened sufficiently so that its restrictive effect on the fuel flow is less than that of the idle `valve 56. Therefore the fuel low under idling conditions is controlled primarily by the valve 56 in accordance with the position of the throttle, and `not by the pressure meter 42 in accordance with the mass of air entering the engine.

While I have illustrated a particular type of carburetor, it will be appreciated by those skilled in the art that my invention may be applied `with equal facility to .other types of carburetore. The carburetor illustrated may, for example, be modied by omitting the pressure regulator 43 and placing 'the valve Se of the fuel meter 42 dit rectly in the `fuel line between the pump and the mixture control 52. This would require that the valve 95 be reversed so that it would open in a downward direction and close in an upward di rectionthe same as the present valve 46.

iii

Upon @opening .ofvthe throttle 4t6., kthe .pressure meter '42 fand the devices 'associated therewith, operating as already described, :Serve to increase lthe :rate zof .uel :supply so cas to maintain the same fuel-toeair ratio, rbut when there is a sudden zopening of the throttle, `such as accompan- :ies `a sudden Aacceleration 4|oi the engine, 'the `said pressure -meter .and associated devices, las heretofore described, `may :act too slowly, with the result that the `fuel-to-.air raft-io is seriously re duced during the period of acceleration. Similar, but opposite, conditions result .from a sudden .closing of the throttle, such 4as accompan- Ties a .sudden deceleration of the engine. To

l meet this condition, ineans have been `provided,

as illustrated 'for instance 'in -my said co-pend ting application, for utilizing the suddenly inh creased or decreased air pressure in the main air conduit 'to cause an increased Aor decreased quantity -o'f fuel to be delivered during a limit- 'ed period of time. ln accordance with the present invention, similar results are obtained with out `-depending upon Vchanges in air pressure but lby means mechanically yoperable in accordance with the Vthrottle movement.

The aforesaid `means mechanically operable in accordance -with the throttle movement, can be Widely varied as to details but, by way of example, I have shown a valve 'unit |34 having a :chamber |36 connected with the fuel conduit 44 by mea-nsof a conduit |38. A conduit |40 leads from thecha-mber |36 to a supplemental discharge nozzle |42 lin 'the main air passage. The valve 'unit 34 alsohas chambers |44 and |46 separated by a flexible diaphragm |48 and connected by 'Si restriction |50. Opera-bly connected with the dia-- phragm |48 -is a vail-ve |52 which normally closes the conduit |40 and which is biased toward its closed. position by means of a coil sprirnT 54 in the chamber vv|46, the valve being normally closed. The conduit |38, the `chamber |36 and the conduit 14D will be referred to collectively as the secondary fuel conduit.

'For operating the valve unit 34, I provide a pressure unit in the form of an accelerating in the rod |62 and is engaged by opposed coil springs |68 and Il@ carried in the slot which tend to center `the pin |66 therein.

The left end of the cylinder |58 is connected by conduit |72 with the chamber |44 of the valve uni-t |34 and is also connected with the before mentioned conduit 2 thru a restriction |14. The right end of the cylinder 58 is connected by Aa conduit |16 with the chamber |46 of the Valve unit V|34 and is also connected by a conduit |18 with the before-mentioned conduit 58 at the downstream side of the idle valve. The connection from lthe chamber IBB of the pressure meter 42 may be traced thru the conduit H2, the re striction |74, the conduit |12, the chamber |44., the restriction ld, the chamber |46-, the conduit l i5, the right end of the cylinder |53 and the conduit H8 to the conduit 5B. Thus when thereis no movement of the plunger its the pressure in the chamber lili) is the same as the pressure at F: the downstream side of the idle Valve` When the throttle I6 is moved suddenly in the opening direction the plunger li! is moved suddenly toward the left, thus forcing fuel thru the conduit |12 into the chamber V|44 and withdrawing fuel thru the conduit |16 from chamber |46. This causes the diaphragm |48 to move upward to open the valve |52 and permit fuel to `flow thru the conduit |40 to the supplemental discharge nozzle |42 and effect a boosting laction. The increased pressure in the chamber |44 willbe dissipated thru the restriction |50, but by making this restriction of a suitable size the valve |52 can be kept open for any required length of time to permit the engine to fully accelerate before the supplemental supply of fuel is cut oifj As soon as the pressures in the chambers |44 and |46 are equalized, the valve |52 is closed by the spring |54.

ASudden movement of the plunger |60 toward the left also forces some of the fuel thru the restriction |14 and the conduit ||2 into the chamber of the pressure meter 42, thus increasing the pressure in that chamber. This increased pressure disturbs the balance theretofore existing in the pressure meter, and the valve 96 is moved in the downward or closing direction. This increases the pressure in the chamber |04 and correspondingly increases the pressure in the chamber 68 of the pressure regulator v4&3, thus moving the valve 46 in the opening direction and increasing the rate of flow of fuel thru the main fuel conduit and eifecting an additional boosting action. This increased pressure in the chamber |00 is maintained so long as there is incr-eased pressure in the chamber |44 of the valve unit'l34. When this increased pressure in the ychamber |44 is dissipated thru the restriction |50, the pressure in the chamber |00 is correspondingly reduced andthe valve 96 is permitted to move to the position determined by the new balance of pressures established by the increased air flow resulting from the increased throttle opening. From the foregoing description it will be apparent that the connections for varying the pressure in the chamber |00 constitute supplemental fluid operated means for operating the pressure regulator 48 additionally-t0 the normal operation thereof, the said normal operation being in accordance with variations in air presL sure differential. A

From the foregoing description it will be ap parent that the sudden opening of the throttle and corresponding sudden movement of the plunger |54 toward the left serves not only to open the secondary fuel conduit to permit to pass therethru, but also to increase the rate of flow of fuel thru the main fuel conduit.

When the throttle IS is moved suddenly in the closing direction the plunger |60 is moved toward the right, but the spring |68 is compressed and the plunger movement may be relatively slow. Some of the fuel inthe right end of the cylinder passes thru the conduit |16 into the chamber |46, but the valve |52 is not moved inasmuch as it is already closed. At the same time some 'of the fuel passes thru the conduit |18 intor the conduit 58. The quantity of fuel so Idelivered into conduit 53 is so small, however, compared withy the amount regularly flowing thru conduit 58,that its effect on the operation of the engine is not appreciable. Fuel is simultaneously withdrawn thru the conduit |12 from the chamber |44 and is also withdrawn'thru the restriction i|14 and the conduit ||2 from the chamber |00. Withdrawal of fuel from Athechamber||l|l` decreases the pressure therein, and this decreased pressure disturbs the balance theretofore existing in the pressure meter and the valve 96 is moved inthe upward or opening direction. This decreases the pressure in the chamber |04 and correspondingly decreases the pressure in the chamber 68 of the pressure regulator 48, thus moving the valve 46 in the closing direction and decreasing the rate of flow of fuel thru the main fuel conduit and effecting a robbing action.

It will be clear that fuel can flow into the left end of the cylinder only at the rate permitted 'by the rectrictions |50 and |14. By properly determining the Sizes of these restrictions the rate of movement of the plunger |60 under'the in',- fluence of the spring |68 can be predetermined, with the result that the before-mentioned decreased pressure in the chamber |00 can be maintained for a period of time suiiicient to permit the engine to fully decelerate before the rate of fuel flow is increased to that determined bythe new balance of pressures in the pressure meter established by the decreased air flow resulting from the decreased throttle opening. f

When the throttle is moved slowly in the open'- ing direction or in the closing direction, the plunger |60 is moved slowly, and the restriction |50 -maintains an equalized pressure in the chambers |44 and |46. The valve |52 remains closed and there is no change of pressure in the chamber It has been made clear that upon a sudden opening movement of the throttle a single means, that is the pump |56, serves in associationwith other parts to cause fuel flow thru the secondary fuel conduit and also to cause increased fuel flow thru the main fuel conduit, and that this same means upon a sudden closing movement of the throttle serves to cause decreased fuel ow thru the main fuel conduit. It is thereforeto be understood that, when a single. means serves as sated, the invention is not necessarily limited to a mechanical connection between such means and the throttle, it being only necessary that the means be operable when the throttle is suddenly moved whether as the resulty of mechanical connection or o-therwise. l

While I have shown and described a certain preferred embodiment 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. A fuel supply system for ian internal com'- bustion engine, comprising a passage including a venturi therein for air flowing to said engine for combustion purposes, a throttle for controlling the flow of air vthru the passage, a'source of fuel under pressure, a main fuel conduit connected with the fuel source and serving to supply fuel to the engine, means controlled by variations in air pressure differential at the venturi for varying the rate of fuel supply thru the main fuel conduit in accordance with variations in the rate of air flow, a secondary fuel conduit connected with the fuel source and adapted to upply fuel to the engine, two chambers connected by a restriction and separated by a flexible diaphragm, avalve operably connected with the diaphragm and biased to normally close the secondary fuel conduit, a pressure unit comprising a cylinder and a plunger therein mechanically connected to be moved with the throttle upon movement thereof in the opening direction, and two con.- duits .connecting the end portions ,of the cyl inder with the respective chambers .whereby movement of the plunger corresponding to throttle movement in the opening direction serves ,to force liquid into one chamber and .to withdraw liquid from the other chamber and to thereby tend to. move the disphragm in the valve opening direction, the dissipation of liquid thru the restriction permitting the spring `to hold the valve closed when the throttle and plunger are moved slowly but the valve being opened in opposition to the spring when the throttle and plungerare moved suddenly.

2. The combination in a `fuel supply system for an internal combustion engine, a passage including a venturi thereon for air flowing :to said engine for combustion purposes, a throttle for controlling the flow of air thru the passage, a fuel conduit serving to supply fuel to the engine and having a jet system therein, a pressure regulator Aincluding a valve for controlling the flow of fuel `thru the fuel conduit, a pressure meter having Atwo chambers separated by a flexible diaphragm and connected to apply tothe `diaphrtgdrl pressures varying with the air pressure `differential at the venturi, the .pressure meter also Vhaving a rst. fuel containing chamber which is unrestriotedly connected with the pressure regulator and in which the pressure is .varied by a pressure controlled valve so that pressure variations in the said chamberbperate the pressure regulator and the said pressure meter also having a second fuel containing chamber connected with the fuel conduit. at the low pressure side ofthe jetsystem, and a device hydraulically connected in series between said second cham-- ber the low pressure side of said jet system, and `mechanically connected for operation in unison with the throttle, `and serving upon sudden movement of the throttle to change the pressure in said second chamber of the pressure meter and thereby move `the pressure meter valve so as to operate the pressure. regulator and thereby temporarily change the rate of fuel supply.

.3. A fuel supply system for an internal combustion engine, comprising a main fuel conduit, a secondary fuel conduit connected in vparallel with said main conduit, first and second valves for .controlling the flow of fuel thru said main and secondary conduits respectively, operating means Vfor each said valve, each operating means including an expansible chamber having a movable wall connected to its associated valve and adapted to move said valve in a direction to increase the fuel flow thru its associated conduit .in response to an increase .in pressure in saidchamber, a throttle for controlling the now of come bustion ai;` to said engine, a pump operable to discharge fluid upon a opening movement. of the throttle, fluid pressure connections between the pump outlet and said chambers, and a pressure relief passage from each of said chambers including a Yfixed restriction, said passages being effective to relievepressures due to slow opening movements of said throttle, said pump being effective upon. a rapid `opening movement of said throttle to increase the pressures in said chambers and thereby cause an opening movement of both said valves for a predetermined time.

4, A fuel supply system for an internal combustion engine, comprising a main `fuel conduit, a secondaryfuel conduit connected in ,parallel ,with seid `vilain .Conduit @rst and second. Arali/.es ser controlling .the flow .of fuel thru said main. and secondary conduits respectively, operating means for `each said valve, `each operating means including an expansible chamber having a movable wall .connected to its associated .valve .and adapted to move said valve in a direction .to increase the, fuel flow thru its associated .conduit in response to an increase in pressure in said chamber, a. throttle for controlling the flow of combustionair to said engine, a pump operable. in one direction or the other upon an .opening or closing movement of the throttle, connections between thepump and said chambers enabling the pump ,to increase the pressure in both chambers upon movement inone direction and enabling the pump to decrease the pressure in the chamber forthe rst valve upon movement in the .other direction, anda pressure relief passage for said chambers including a xed restriction, said passage being elfective to avoid pressure `changes. .due to slow opening movements of said pump and said .restriction enabling the pump to be effectiveupon a rapid `opening movement of .said throttle ,tomcrease the pressure in both chambers and therebyv cause an opening movement. of .both said valves. for a predetermined time. and to beeiective` .upon a rapid closing movement of `said throttle to decrease the pressure in the chamber for the first, valve and thereby cause a` closing movement ,of said valve for a .predetermined time.

5. A fuel supply system for an internal.` ,combustion engine, comprising a .main fuel conduit, a secondary fuel conduit connected in .parallel with said main conduit, first and second .valves for controlling the flow of fuel `thru said main and secondary conduits respectively, .operating means for each said valve, each operating means including an expansible chamber having .a .movable wall connected to its associated valve .and adapted to move said valve -n` a direction Lto. increase the fuel flowthru its associated conduit in response to an increase in pressure insaidchamber, a throttle for `controlling the flow of combustion air to said engine, .a pump `nfiechanically connected with said throttle to move in` unison therewith so as to discharge fluid upon an opening .movement thereof, fluid .pressure connections` between the pump outlet and saidchambers, and a pressure .relief passage from each of .saidnhambers including a fixed restriction, said passages being effective to relieve pressures due vto slow opening movements of `said throttle, .said pump being effective upon a rapid opening movement of said throttle to increase the pressures in said chambers and` thereby cause. an opening movement of both said valves for a predetermined time.

6. A fuel supply system for an internal combustion engine, comprising a main fuel conduit, a, metering restriction in said main fuel conduit, first Valve means for controlling the flow of fuel thru said main conduit, means for Aoperating said rst valve means under all conditions of engine operation including an expansible chamber having a movable wall connected-to said valve means and fluid pressure means connecting said chamber and said main fuel conduit on the down- `streamside of said metering restriction, said valve operating means being effective upon an increase in the pressure in said chamber to-move said valve means in a fuel flow increasing direction, a-secondary fuel conduit connected in parallel with said main conduit, second valve means for controlling the flowof fuel thru said secondary` condutnoperatins means forsaidseondvalve means Y ii" including a second expansible chamber' having a movable wall connected to said second valve means and adapted to move said second valve means in a fuel flow increasing direction in response to an increase in pressure in said second chamber, means biasing said second valve means to closed position, a throttle for controlling the flow of combustion air to said engine, a pump operable to discharge fluid upon an opening movement of the throttle, fluid pressure means conn nesting the pump outlet with both of said chambers, and a pressure relief passage for said chamlbers including a fixed restriction, said passage 'being effective to relieve pressuresproduced by said pump upon slow opening movements of said throttle, said pump being effective upon a rapid opening movement of said throttle to increase the pressure in both said chambers and thereby to `cause an additional opening movement of said first valve means and to open said second valve means for a predetermined time.

7. A fuel supply system for an internal cornbustion engine, comprising a main fuel conduit, a metering restriction in said main fuel conduit,

Y first valve means for controlling the flow of fuel thru said main conduit, means for operating said first valve means under all conditions of engine operation including an expansible chamber having a movable wall connected to said valve means and fluid pressure means connecting said cham- I ber and said main fuel conduit on the downstream side of said metering restriction, said valve operating means being effective upon an increase in the pressure in said chamber to move said valve means in a fuel flow increasing direction, a secondary fuel conduit connected in parallel with said main conduit, second valve means for controlling the flow of fuel thru said secondary conduit, operating means for said second valve means including a second expansible cham- Y ber having a movable Wall connected tosaid second valve means and adapted to move said second valve means in a fuel flow increasing direction in response to an increase in pressure in said second chamber, means biasing said second valve means to closed position, a throttle for controlling the flow of combustion air to said engine, a pump mechanically connected'to said throttle to move in unison therewith so as to discharge fluid upon an opening movement thereof, fluid pressure means, connecting the pump outlet with both of said chambers, and a pressure relief passage for said chambers including a fixed restriction, said passage being effective to relieve pressures pro- Vduced by said pump upon slow opening movements of said throttle, said pump being effective upon a rapid opening movement of said throttle to increase the pressure in both said chambers and thereby to cause an additional opening move- Y ment of said first valve means and to open said second valve means for a predetermined time.

8. In a fuel supply system for an internal combustion engine, the combination of a passage including a venturi therein for air flowing to said engine for combustion purposes, a throttle for controlling the flow of air thru the passage, a

source of fuel under pressure, a secondary fuel conduit connected with the fuel source and adapted to supply fuel to the engine, a normally closed valve in the secondary fuel conduit, a main fuel conduiteconne'cted with the fuel source and serving to supply fuel to the engine, a pressure regulator including a valve for controlling the flow of fuel thru the main fuel conduit, a pressure meter, separate from said pressure regulator,

12 controlled by variations in air pressure differeiid tial at the venturi, for normally controlling the operation of the pressure regulator to vary the rate of fuel supply thru the main fuel conduit in accordance With variations in the rate of air flow, supplemental means for operating the pressure regulator so as to temporarily increase the rate of fuel supply to the engine, said supplemental means including said pressure meter and a fluid displacement device mechanically connected to the throttle and operating in unison therewith for opening the valve in the secondary fuel conduit and also serving upon sudden opening of the throttle to cause said pressure regulator to temporarily increase the rate of fuel supply thru the main fuel conduit.

' 9. In a fuel supply system for an internal com-Y bustion engine, the combination of a passage including a venturi therein for air flowing to said engine for combustion purposes, a throttle for controlling the flow of air thru the passage, a source of fuel under pressure, a secondary fuel conduit connected with the fuel source and adapted to supply fuel to the engine, a valve operating unit comprising two chambers connected by a restriction and separated by a flexible diaphragm, a valve operably connected with the diaphragm and biased to normally close the secondary fuel conduit, a main fuel conduit connected with the fuel source and serving to supply fuel to the engine, a pressure regulator including a valve for controlling the flow of fuel thru the main fuel conduit, a pressure meter controlled by variations in air pressure differential at the venturi and normally operating the pressure regulator to vary the rate of fuel supply thru the main fuel c-onduit in accordance withrvariations in the rate of air flow, supplemental fluid operated means for operating the pressure regulator additionally to thenormal operation thereof, a pump comprising a cylinder and a plunger therein mechanically connected to beV moved with the throttle upon movement thereof in the opening Y direction, two conduits connecting the end portions of the cylinder with the respective chambers of the valve operating unit whereby movement of the plunger serves to force liquid into one chamber and to withdraw liquid from the other chamber and to thereby tend to move the diaphragm in the valve opening direction, and a conduit connecting one end of the cylinder of the pump with the supplemental fluid operated means, whereby the said means operates the pressure regulator so as to temporarily increase the rate of fuel supply thru the main fuel conduit.

10. In a fuel supply system for an internal combustion engine, the combination4 of a passage including a venturi therein for air flowing to said engine for combustion purposes, a throttle for controlling the flow of air thru the passage, a source of fuel under pressure, a secondary fuel conduit connected with the fuel source and. adapted to supply fuel to the engine, a normally closed valve in the secondary fuel conduit, 'a main fuel conduit connected With the fuel source and serving to supply fuel to the engine, a pres-` sure regulator including a Valve for controlling Vthe flow of fuel'thru the main fuel conduit, a

pressure meter, separate from said pressure reg' ulator, controlled by Vvariations in air pressure differential at the venturi, for normallyY .controlling the operation of the pressure regulator to vary the rate of fuel supply thru the main fuel conduit in accordance with variations in the rate of air flow, supplemental .means for operating the pressure regulator so as to temporarily vary the rate of fuel supply to the engine, said supplemental mea-ns including said pressure meter and a fluid displacement device mechanically connected to the throttle and operating in unison therewith for opening the valve in the secondary fuel conduit and also serving upon sudden throttle movement to cause the said pressure regulator to temporarily vary the rate of fuel supply thru the main fuel conduit.

11. In a fuel supply system for an internal combustion engine, the combination of a passage including a Venturi therein for air flowing to said engine for combustion purposes, a throttle for controlling the flow of air thru the passage. a source of fuel under pressure, a secondary fuel conduit connected with the fuel source and adapted to supply fuel to the engine, a normally closed valve in the secondary fuel conduit, a main fuel conduit connected with the fuel source and serving to supply fuel to the engine, a pressure regulator including a valve for controlling the flow of fuel thru the main fuel conduit, a pressure meter, separate from said pressure regulator, controlled by variations in air pressure dierential at the venturi, for normally controlling the operation of the pressure regulator to vary the rate of fuel supply thru the main fuel conduit in accordance with variations in the rate of air flow, and a ud displacement device 111echanically connected to the throttle and operating in unison therewith and upon sudden throttle movement in the opening direction serving to open the valve in the secondary fuel conduit and also serving upon sudden throttle movement in the opening direction to cause the pressure meter to operate the pressure regulator so as to temporarily increase the rate of fuel supply thru the main fuel conduit.

SCOTT F. HUNT.

REFERENCES CITED The following references are of record inthe le of this patent:

UNITED STATES PATENTS Number Name Date 1,881,559 Heitger Oct. 11, 1932 2,025,504 Geiger Dec. 24, 1935 2,092,685 Viel Sept. 7. 1937 2,277,930 Mock et al Mar. 31, 1942 2,316,300 Udale Apr. 13, 1943 2,387,271 Kittler et a1. Oct. 23, 1945 2,391,755 Twyman Dec. 25, 1945 FOREIGN PATENTS Number Country Date 487,176 Great Britain June 16, 1938