US2456604A

US2456604A - Fuel supply system

Info

Publication number: US2456604A
Application number: US607290A
Authority: US
Inventors: Barfod Frederik; Emil O Wirth
Original assignee: Bendix Aviation Corp
Current assignee: Bendix Aviation Corp
Priority date: 1945-07-27
Filing date: 1945-07-27
Publication date: 1948-12-14
Anticipated expiration: 1965-12-14

Description

Dec. 14, 1948. F. BARFOD Erm.

FUEL SUPPLY SYSTEH 2 Sheets-Sheet 1 Filed July 27. 1945 .s nu U- mw n u a @ma ...n n. om .vom ww NQ m 0m dm w m ONM. am n n Nom @P ON NGN NSN O VN JN .Nm \L om Y .aN @o @M fr .NPN 3N Qv. 0r 0.o On Mmm U\ um lmao. um HN. ..\|um N. r..\ u k om @d Dec. 14, 1948.

F. BARFOD ETAL FUEL SUPPLY SYSTEM Filed July 27. 1.945

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20c, 22 25a m I4 20a. 200 ze El?. am mVENToR. *au ale mzeoeznc amapola 40, I y Emu. QwnzTH ATTORNEY Patented Dec. 14, 1948 FUEL SUPPLY SYSTEM Frederik Barfod and Emil O. Wirth, South Bend, Y Ind., assignors to Bendix Aviation Corporation,

South Bend, Ind., a corporation of Delaware Application July 27, 1945, Serial No. 607,290

46 Claims. l

This invention relates to fuel supply systems or devices for internal combustion engines and more' particularly to devices or systems in which liquid fuel is supplied under positive pressure.

An important object of the invention is to provide a fuel feeding system in which the fuel flow is automatically regulated in accordance with certain engine variables, among which are for example, engine speed, temperature and charging pressure.

This fuel supply system, while especially applicable to fuel supply systems of the character hereinafter particularly described, is not limited to such uses, but is obviously available, with or Without modification, in a great variety of cases where fuel is intended to be supplied under more or less analogous conditions in an internal combustion engine or other fuel consuming device.

Another object of the invention is to provide a generally new and improved fuel supply system for automatically controlling the fuel to air ratio under various engine operating conditions.

Further objects and advantages of the invention will be apparent, to those skilled in the art, from the following detailed description, taken in connection with the accompanying drawings. Although but one embodiment is shown, skilled persons will understand that many variations may be made without departing from the principles disclosed, and I contemplate the employment of any structures, arrangements, or modes of operation that are properly within the scope of the appended claims.

In the drawings:

Figure l is a diagrammatic sectional view of a fuel system embodying the present invention;

Figure 2 is an enlarged diagrammatic sectional view of an alternative arrangement for compensating for exhaust back pressure.

Figure 3 is an enlarged diagrammatic sectional view of the idle cut off means; and

Figure 4 is an enlarged diagrammatic sectional view of the acceleration device.

Referring now to Figure 1, there is shown an induction passage I having an air inlet l2, and a mixture outlet I4 connected to the intake manifold I6 of an internal combustion engine, not shown, or to a supercharger inlet, should asupercharger be used, the induction passage I0 being controlled by a throttle valve I8. A supercharger might alternate'y be connected to the inlet I2 or such a device might be connected to both the inlet i2 andthe outlet I4. Liquid fuel is supplied by a pump, indicated generally at 20, which may be operated by the engine, or by any other suit- (Cl. 12S- 119) able means, and is capable of supplying fuel under positive, preferably but not necessarily substantially constant, predetermined pressure. This pump may be of any well known type but, as shown, is of the sliding vane type having an inlet 22 receiving fuel from a source, an outlet conduit 24 and a bypass 28 controlled by a pressure responsive valve 30. Fuel from the pump is delivered from the pump outlet conduit 24 to a passage 32 which communicates with a passage 33 connected with a chamber 34 in the casing of a fuel discharge control unit generally at 36, the fuel pressure in said chamber 34 being at all times substantially the same as that in passage 33, and this pressure in said chamber and passage being hereinafter referred to as pressure A or control pressure. One wall of chamber 34 is closed by a flexible diaphragm 38 which is marginally clamped between said casing of the unit 36 and a shoulder of the body 40 of the device. A restriction or jet 42 is provided between the passages 32 and 33 through which fuel is adapted to flow.

Passage 32 is provided with a branch passage 44 which communicates with the impeller chamber 46 of a pump, indicated generally at 4l. This pump, as shown, is of the centrifugal type which includes an impeller 48 driven by the engine through a shaft 50 which is suitably connected, by any well known means, with said engine which is not shown herein but which rotates said impeller in direct proportion to the R. P. M. of said engine and is adapted to build up an outlet pressure which provides the metering head for the system.

The outlet of pump 41 is connected to a passage 52 which communicates with a passage 53 which in turn communicates with a chamber 54 on the side of the diaphragm 38 opposite the chamber 34. A metering restriction or jet 56 is provided between passages 52 and`53 and the pressure of fuel in said chamber 54 is normally substantially the same as that in the passage 53 posterior to the jet 56, said pressure in chamber 54 and passage 53 posterior to jet 5B being hereinafter referred to as pressure B or metered fuel pressure.

Chamber 54 has an outlet connected by a conduit 58 with a fuel nozzle member 60 discharging into the induction passage posterior to the throttle valve. Air is bled into the nozzle member 60 through cross passages 6| in a tip portion 62 of an air tube 63 having an air passage 63a therein receiving air from a tube 64 by way of a passage 65; the tube 64 being located in the air entrance l2 of the induction passage and adapted to receive the impact of air entering said induction passage. Tip portion 62 extends part way into the fuel passage of the nozzle and the fuel emulsion is discharged from an annular groove 66 between the shoulder at the base of said portion 62 and the adjacent end of nozzle 60. As best shown in Figure 3 there is an outlet for the chamber 54 which is provided with a tting 61 having a bore within which a fiat sided or fluted valve 68 is slidably guided, said valve having a conical tip 69 cooperating with a valve seat in said fitting for controlling the discharge of fuel from chamber 54. The end of the valve 68 opposite the conical tip is attached to the diaphragm 38. As shown, said attached end is riveted over at 1I and washer-like

spring retainer cups

12 and 14 are disposed on opposite sides of the diaphragm to reinforce the central portion of same. spring retainers have their peripheral edge portions turned outwardly, relative to the diaphragm, thus preventing the diaphragm from being cut or otherwise injured thereby and providing means for retaining the adjacent ends of springs 16 and 18 disposed respectively in

chambers

54 and 34. These springs are preferably light and of substantially the same calibration although they may have other characteristics. Spring 16 reacts between the spring retainer 14 and one wall of the chamber 54 for urging the valve 68 in the opening direction, while spring 18 reacts between retainer 12 and a spring retainer 80 disposed in chamber 34, and attached to a diaphragm 8| forming one wall of said chamber 34, said spring being adapted to urge the valve 68 in the closing direction. The effective force of the springs is adjustable, a plunger 82, slidably received in a bushing 83 screwed into an opening in a casing member 84 within which is a chamber 85 vented to atmosphere at 85a. It is to be understood that preferably the adjustment is such that the valve 68 is normally slightly open when the engine is inoperative, for a purpose to be described hereinafter.

Referring again to Figure 1 the passages 52 and 33 are connected together by a conduit 86. One end of said conduit communicates with the passage 52 anterior to the restriction 56 and the other end communicates with the passage 33, there being a restriction or orifice 88 Provided in the conduit 86. It is to be noted that the fuel pressure in that portion of conduit 86 which is on the centrifugal pump side of orifice 88, that is between orifice 88 and conduit 52, is at all times substantially the same as the pressure in that portion of the passage 52 anterior to .1ct 56 and the pressure in said portions of the conduit and passage will be hereinafter referred to as pressure C.

Means for varying the effective size of orifice 88 comprises a valve 92 controlled by a suction responsive device indicated generally at 93. The valve 92 is connected to or formed integral with a valve stem 94 slidable in a guide 96, said stem 94 being connected at its outer end to a. plate 98 forming one wall of a sealed expanslble bellows |00 enclosed by a casing |02 which is supported on the body by screws, not shown, or by any other suitable well known means. The 'casing is subjected to engine charging pressure by means of a conduit |86 which com-.- municates with the interior of said casing adjacent the lower portion thereof so as to draw oft any fuel which may seep past the stem 94, and as shown communicates `with the induction pas- It is to be noted that said sage posterior to the throttle valve I8. However, if -a supercharger is used, conduit |06 is connected to the engine manifold posterior to the supercharger. The valve 92 is therefore controlled in accordance with engine charging pressure which reflects throttle position and engine speed and load. A light compression spring |88 may be provided within the bellows, an arrangement that is particularly desirable, if the bellows is partially or completely evacuated, to extend the bellows to a normal balancing position and it may be desirable for said spring and bellows to be so calibrated and arranged that the valve 92 will be normally closed when the pressure in the casing |02 is at its highest operating value.

It is also to be noted that the pressure in branch passage 44 is at all times substantially the same as that in passage 32 and the pressure in said passages will be hereinafter referred to as pressure D or pump inlet pressure.

OperatiO/nI During normal operation fuel is supplied under pressure to the inlet 44 of the centrifugal pump 41 by means suchas the fuel pump 28 although other means may also be employed to supply fuel to said inlet 44. Fuel received by pump 41 is discharged under an increased pressure into passage 52 from which it flows through metering orifice 56 to chamber 54, past valve 68 which is opened by the pressure of fuel in cham ber 54 acting on diaphragm 38, into conduit 53, and thence to a nozzle 68 or other fuel dicharge means.

Due to the inherent characteristics of the centrifugal pump 41, the pressure-C at the outlet of pump 41 will be greater than the pump inlet pressure D by an amount which is directly proportional to the square of the speed of the pump and consequently directly proportional to the square of the engine speed.

During operation, with the valve 92 in a partially open position, fuel at pressure C will now through the calibrated restriction 88 into passage 33 and then through orifice 42 to the pump inlet 44. As a consequence the pressure in passage 33, herein referred to as control pressure A, will be of a value intermediate the fuel pressure C and pump inlet pressure D, and its value relative to the pressures C and D will depend upon the effective size of orifice 88 relative to the area of orifice 42. For any fixed setting of valve 32, pressure A will remain greater than pressure D and less than pressure C by amounts representing constant percentages of the difference between pressures A and D. Thus, if orice 88 has an effective area equal to orifice 42, pressure A will remain substantially half way between pressures C and D irrespective of variations in speed of pump 41. It therefore follows that the differential between pressures C and A will likewise vary as the square of engine speed, for a xed setting of valve 92.

Since the

springs

18 and 18 are substantially in balance, except for considerations hereinafter explained, the pressure of the fuel in chamber 54, referred to herein as metered fuel pressure B, will be maintained equal to control pressure A. In the event pressure B should tend to exceed pressure A the valve 68 will tend to open to allow the escape of additional fuel to the nozzle and consequent lowering of pressure B, and the reverse action will occur if B tends to be less than A. It is thus clear that the difference between pressure C and pressure B likewise will vary as the square of the engine speed for a given setting of valve 92.

As is generally known, the quantity of fuel which will flow through a given size metering orince such as metering jet 56 will vary in proportion to the square root of the differential in pressures C and B on opposite sides of the orifice, and since this differential varies as the square of the engine speed, it will be apparent that the quantity of fuel flowing through orifice 56 for a given setting of valve 92 will vary directly as the engine speed.

In view of the fact that the weight of air flow to an engine at a given manifold pressure varies substantially in direct proportion to the engine speed, except for variations caused by variables such as exhaust back pressure and intake air and exhaust gas temperatures which may be compensated for as hereinafter described. However, the device above described will supply fuel to the engine in accordance with the air flow thereto.

If at a given engine speed the manifold or engine charging pressure is increased, the weight of air supplied to the engine will likewise increase, and the quantity of fuel supplied to the engine should be correspondingly increased. This increase in fuel flow is accomplished in the present device by the operation of valve 92. Any increase in charging pressure is transmitted through passage |06 to the chamber within casing |02 and will cause bellows |00 to partially collapse whereupon valve 92 will reduce the effective area of the calibrated restriction 88.

Upon decrease in the effective area of orifice 88, pressure A will be reduced so as to more nearly approach pressure D and as a consequence the valve 66 will open to permit discharge of fuel to the engine at a greater rate such that the pressure B will be reduced to equal new pressure A. In other words, reducing pressure A reduces pressure B and thereby increases the differential between fuel pressure C and metered fuel pressure B. Consequently, fuel is delivered through orifice 56 at a greater rate to compensate for the increase in air flow which instigated the change in pressure A. By properly contouring valve 92, the effective area of orifice 88 may be so controlled as to obtain any desired fuel to air relationship with variations in engine charging pressure.

For example, at conditions of high power output, corresponding to low intake manifold pressure it is generally desirable to increase the richness of the mixture. This'may be readily accomplished by properly shaping the contour of valve 92. If the valve 92 is arranged to maintain the effective area of the metering orifice directly proportional to the manifold pressure, a constant mixture ratio will be obtained. However, if the needle contour is such as to increase the orifice area more rapidly when the charge density drops below a predetermined value, the richness of the mixture will be correspondingly increased, thereby providing a power enrichment as is generally desired.

If desired, other arrangements may be provided for obtaining various desired fuel to air relationships in accordance with engine variables. One such arrangement may be means to vary the effective area of the metering jet, as disclosed in the Barfod application, Serial No. 600,756.

Provision may be made for enriching the idling fuel mixture as is desired. One means for effecting idle enrichment is to adjust valve 68 so that it is normally slightly open. Thus the fuel meter ing differential pressure required to balance the diaphragm valve assembly is increased. Then at low differential pressures. corresponding to idle operation, the arrangement ls of material effect in producing a relatively large increase in fuel flow, thereby providing the desired rich mixture at idle. However at high differential pressures the arrangement has a negligible effect and has substantially no effect on the richness of the fuel mixture which is maintained at the normal fuel to air ratio.

It is thus apparent that the basic structure will provide a substantially constant mixture richness, but by introducing an extraneous factor to effect variations in the position of valve 68 as by varying the area of the metering orifice 86, any fuel metering characteristic may be obtained. Means other than pump 41 might also be used to create a pressure in passage 52 which varies as the square of engine speed.

Economizer Means for modifying the action of the above described fuel system for power enrichment includes a bypass about the metering jet 56. The bypass comprises passages and |22, |23 the former having a connection with the passage 62 anterior to the jet 56 and the latter is connected with the passage 53 which communicates with the chamber 54 as a unit 36. Passage |23, which has a metering restriction |48, connects passages |20 and |23 together. The bypass is controlled by a pressure responsive device or unit, indicated generally at |24, which comprises a fluted valve |26 slidable in the bore of a plug |28, said valve having a conical tip portion |30 which controls a port |32 in said plug. Unit |24 is provided with two chambers, |34 and |36, separated by a flexible diaphragm |38 to which the valve |28 is secured at |40 by riveting or any other suitable means. A spring retainer cup |42 is also attached to the diaphragm and is secured by the riveted over portion of the valve |26, said spring retainer |42 being located in the chamber |36 and has one end of a spring |44 received therein. This spring reacts between sad retainer and a wall of chamber |36 for urging the valve |26 in the closing direction, opening movement of the valve being limited by a lug |46 disposed in chamber |36. 'I'he passage |20 communicates with the chamber |34 while a passage |50 connects passage |22 and the chamber |36 together. l

In the above described economizer, chamber |34 is subjected to fuel under pressure C urging the valve in the opening direction while chamber |36 is subjected to metered fuel pressure B urging the valve in the closing direction, the spring being so calibrated as to normally maintain the valve closed. Therefore, with this arrangement. the engine is supplied with the normal quantity of fuel for the normal fuel to air mixture throughout the normal operating range. However at high speeds the differential between the pressure C and the combined force of pressure B and spring |44 increases sufficiently to effect opening of the valve |26. An additional quantity of fuel is then supplied to the nozzle to provide an enriched mixture for high speed operation, as is desired.

Temperature control Means for modifying the richness of the fuel mixture in accordance with temperature conditions of the engine comprises the unit indicated generally at |60. This means includes a bypass about the metering jet 56 which comprises a passage |62 which communicates with passage |22 through a metering jet |64. The effective ansaeoi ajrea of said jet |64 is controlled by a valve 68 slidable in a guide |68 of the unit |60. The valve |66 has an end portion |10, which tapers to a reduced portion |1|. .The latter is disposed within the metering jet |64 and the tapered portion is adapted to variably control'the area of said iet. The opposite end of the valve |66 is secured to the free end of the bellows |12. The other end of the bellows is provided with a stem |14 screwed into an opening in the casing |16 of the unit |60 whereby the position of the valve, relative to the jet, may be adjusted. A lock nut |18 may be provided for the stem |14 `for securing the device in adjusted positions. A diaphragm |80 is interposed between the valve 66 and the adjacent end of the bellows to thereby provide a seal against entrance of fuel into that portion of the casing |16 in which the bellows is located. A spring/ |82, provided in a chamber |84 of unit |60, is adapted to react between a spring retainer |86 and an end wall of the chamber |84 for urging the valve |66 in the opening direction. If desired a vent |88 may be provided for the chamber |84 to permit free action of the valve, said vent also serving as a drain for any fuel which may seep past the valve stem. If desired said vent may be provided with a conduit to carry away such fuel as may leak into chamber |84 to any suitable disposal point. Also if desired the chamber in which the bellows |12 is located may also be vented to relieve undesirable pressures therein. The interior of the bellows |12 is' connected with a tube or bulb |90 by means of a conduit |92, the tube |90 being located at some suitable point where it will be subjected to the heat of the engine. The bulb |90 is lled with any well known fluid or the like which expands upon a rise in temperature. This fluid also fills the conduit |92 and the bellows |12.

`With the foregoing temperature control arrangement an increase in temperature will effect expansion of the bellows |12 with a resulting closing movement of the valve and diminution of the supply of fuel to the engine; while lowering of the temperature of the engine will effect an opening movement of valve |66 thereby supplying additional fuel enriched to enrich the mixture as normally required for cold operation of the engine. At normal engine operating temperatures only the reduced portion |1| of valve |66 is disposed within the oriiice of jet |64 fo controlling the flow through said jet.

Acceleration device Means for supplying an additional quantity of fuel for acceleration purposes comprising the device indicated generally at 200, Figures 1 and 4. This means includes a passage 202 and a passage 204. Passage 202 is connected with the passage |20 and the passage 204. is connected with the passage 58 leading to the fuel discharge nozzle 60.

Communication between

passages

202 and 204 is by way of a port 206 in a plug 208 of the unit 200. A iluted valve 2| 0 is slidably received in a bore 2| 2 of the plug 208 and is provided with a conical tip 2|4 which cooperates with a valve seat 2|6 at one end of the port 206. The unit 200 includes chambers 2|8 and 220, separated by a flexible diaphragm 224; whereas the

chambers

220 and 222 are separated by a flexible diaphragm 226 of substantially larger area than that of diaphragm 224. Fuel is delivered to the chamber 2 I8 by conduit 202, thence it passes into the passage 204 by way of the port 206 when the valve 2|0 is open. The valve 2|0 has one end connected to the diaphragm at 228 and there is a one-way connection between the diaphragms including a member 230, shown as carried by diaphragm 226, adapted to abut against the end 228 of the valve 2|0. If desired, of course, the member 230 could alternately be attached to diaphragm 224. Diaphragms 226, 224 and valve 2|0 are urged in the valve closing direction by a spring 232, disposed in chamber 222, which reacts between one wall of said chamber and a spring retainer 234 secured to said diaphragm 226.

Chambers

220 and 222 are connected with the induction passage posterior to the throttle valve by a passage 236 and branch passages 238 and240.

It is to be noted that the passage 238, which communicates with chamber 220, is relatively large whereas the passage 240, which communicates with chamber 222, is relatively small.

With the foregoing arrangement the suction posterior to the throttle valve is transmitted to

chambers

220 and 222 and normallythe pressures in said chambers are substantially the same. The spring 232 then urges the valve 2|0 into engagement with the valve seat 2 I6, fuel pressure C in chamber 2| 8 acting on the small diaphragm- 224 being insufficient to effect opening of the valve 2|0. Should the throttle valve be opened, as lfor acceleration of the engine,v the pressure in chamber 220 will rise faster than the pressure in chamber 222 due to the difference in effective areas of the

passages

238 and 240 and the differential of pressures on the diaphragm 236 will then be such as to move the diaphragm 226 to the left, as shown in Figures 1 and 4. The pressure of fuel in chamber 2|8 will then be sufficient to urge the vgliaphragm 224 to the left, as shown in Figures 1 and 4, effecting opening of the valve 2|0 therebysupplying the additional quantity of fuel required to enrich the mixture for acceleration purposes. Assuming that the throttle valve remains in the open position to which it had been moved to accelerate the engine, the pressures in chambers 220 and 222 -will gradually equalize, balancing the differential across diaphragm 226. The spring 232 will then effect closing of the valve 2| 0.

Manual mixture richness control Means for manually controlling the richness of the mixture, indicatedgenerally at 250, includes a branch fuel passage 252, connecting passages 33 and 86 together, there being a metering restriction 254 in passage 252 which is controlled by a valve 256 slidable in a guide 258 of the unit 250.

The unit 250 is provided with a pair of compartments 260 and 262 separated by a flexible diaphragm 264 to which the valve256 is attached, at 266. The -stem portion 268 of the valve 256 is uted to permit the passage of fuel therepast into the chamber 260 for urging the diaphragm 264 in the valve opening direction. Chamber 262 is vented to atmosphere at 210 to prevent the creation of undesirable pressures in said chamber 262 which might interfere with the functioning of the unit 250. A plunger 212 is slidably received in a bushing 214 secured in an opening in housing 216 of the unit 250, said plunger having a head 218 adapted to engage the end 266 of valve stem 268. The plunger 212 is adapted to be actuated by a lever 280, pivoted at 282, and having an arm 284 adapted to engage the outer free end of said plunger. The lever 280 is adapted to be manually actuated from a distance or otherwise by any suitable well known means, such as a Bowden wire or like means, not shown, and movement of said lever 280 in a counterclockwise direction will eiect closing of the valve 288. Should it be desired to vary the richness of the mixture from that provided when the valve 256 is closed, the lever 280 is manually actuated in a clockwise direction, whereupon the pressure of fuel transmitted from passage 33 into chamber 260 will force the diaphragm 264 to the right, as shown in Figure 1, and eil'ect opening of the valve 256. The opening movement of said valve being limited by the position of the arm 284 of lever 280.

When the valve 268 is opened there will be a temporary change in the pressures within the system, similar to the changes that will occur upon opening of valve 82, which will result in a reduction in the quantity of fuel delivered to the engine. As long as other factors or variables remain the same such reduction in the quantity of fuel delivered to the engine will result in a leaning of the mixture. Subsequent reverse action of the valve 266 will result in richening the mixture.

Idle cut o# The lever 280 may be provided with a second arm 286 adapted to engage the free end of the plunger 82. upon clockwise movement of said lever 280, for closing the valve 68 when it is desired to shutoff the engine. The plunger 82 is provided with an annular flange 288 which limits the outward movement thereof in the bushing 83. Upon inward movement of the plunger a lug 280, attached to diaphragm 8| and located in chamber 34, is moved in the direction of the head 1| of valve 68 for urging said valve to the left, as shown in Figure 1, to the closed position, whereupon the ilow of fuel past said valve will be cut off.

It is to be noted that the lug 290 is of such length that during normal operation when the plunger 82 is fully extended to its outward limit of movement the free end of lug 280 is spaced .from the head 1| to permit the normal movement of diaphragm 38 and consequent control of the valve 68 by the differential of pressure across said diaphragm. Movement of diaphragm 8|' to the right, as shown in Figure 1. is limited by engagement of a head 292 against the adjacent end of the plunger 82.

Alternative temperature control device If desired an arrangement may be provided in the present fuel system for compensating for exhaust back pressure; an arrangement which could be substituted for the unit 83 and which is shown in Figure 2, being designated generally by the reference numeral 300.

The valve 92 controls the effective area of the restriction 88 (as ln the arrangement shown in Figure 1), said valve being in turn controlled by a pressure responsibe bellows or capsule 302 which is responsive to engine charging pressure or the pressure in the intake manifold posterior to the throttle valve. Any suitable means may be used to secure the valve 92 to the bellows but as shown the stem 94 of said valve is provided, adjacent its outer end, with a flange 304 which is received in a recess 306 ln a closure plate 308 to which the free end of bellows 302 is secured. A bushing 3|0 is press tted into the recess 306 to prevent detachment of the valve from the plate. The outer end of the bellows 302 is attached to a closure plate 3I2 and within said bellows it is desirable (though not necessary) to provide a calibrated loading spring 3|4 which reacts between plates 308 and 3l2 for maintaining said bellows in an equilibrium position at given external and internal pressures. The bellows 302 in the present instance is evacuated to render it responsive to changes in pressure only, temperature compensation being had through a separate control element, to be described. If desired, the loading spring 3I4 may be supplemented by a second spring to facilitate accurate changes; although such second spring need not necessarily be used.

Exhaust back-pressure compensation is provided by means including a capsule or bellows 316, of reduced size with respect to the bellows 302. The inner end of bellows 3I6 is secured to a closure plate 3I8 connected to a plate 3I2 by a stem 320 and the opposite end of said bellows is secured to another closure plate, 322, having a stem 324 threaded in the outer end of a housing 322a, said stem having a passage 326 communicating with the interior of bellows 3|6. The passage 326 may be vented to atmosphere but is preferably connected with a point in the exhaust manifold of the engine by means of a conduit 328.

It is to be understood that the foregoing arrangement is a diagrammatic disclosure and that if desired other constructions and arrangements may be used. Another Aexample of such an arrangement being disclosed in the copending application of Frank C. Mock, for Fuel feeding systems, Serial No. 586,223, led April 2, 1945.

It will be seen that when an increase in manifold or engine charging pressure is transmitted to the casing 322, it will tend to collapse the bellows 302 and 3I6 and move the valve 92 in the closing direction which tends to effect an increase in the quantity of fuel supplied to the engine. Since the bellows 3| 6 i s vented to the exhaust manifold, its collapsing action will be resisted in direct relation to changes in exhaust back pressure. Thus, if engine charging pressure remains the same and exhaust back Dressure should increase the valve 92 would tend to open and effect a reduction in the quantity of fuel delivered to the engine. Preferably the unit 300 is calibrated to produce constant travel of the needle 92 proportional to manifold pressure modified by some predetermined increment of exhaust back pressure. This action can be obtained with a single bellows capsule, but the dual-bellows arrangement herein disclosed has been found more advantageous and practical in general than a single-bellows unit. The particular increment or fraction of the exhaust back pressure to be used is a, variable depending upon the type of engine and its characteristics, particularly with respect to the quantity of residual exhaust gas remaining in the engine cylinder following the exhaust stroke of the engine piston. For use in conventional present day reciprocating engines, an increment equal to one-sixth of the exhaust back pressure provides a satisfactory back pressure correction.

A needle valve 330, Figure 1, may also be provided to adjust the system to meet the reduirements of various installations, said valve 330 cooperating with a restricted orice 332 to control the fuel flow between passages 86 and 33.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the parts without departing from the spirit and scope of the invention or sacrificing all of its material advantages.

a source of fuel with the engine; means vfor creatlng a fuel pressure in and effecting a flow of fuel l through said conduit, the quantity of which will vary directly as the engine speed; means for controlling said flow; means adapted to contain a control pressure developed by the first mentioned means and acting on the second mentioned means for influencing the functioning thereof; and manually controlled means for varying the control pressure.

2. In a fuel system for an internal combustion engine: a source of fuel; a conduit connecting said fuel with the engine; means for creating a fuel pressure in and eecting a flow of fuel through said conduit, the quantity of which will vary directly as the engine speed; means for controlling said flow; means adapted to contain a control pressure developed by the first mentioned means and acting on the second mentioned 3. The invention defined by claim 2 wherein there is also manually controlled means for regulating the control pressure.

4. The invention defined by claim 2 wherein there is a valve for effecting variations ln the control pressure; and there is manual means for alternately actuating the regulating means and the shut ofi means.

5. In a fuel system for an internal combustion engine: a source offuel; a, conduit connecting said fuel source with the engine; means for creating a fuel pressure in and effecting a ow of fuel through said conduit, the quantity of which will vary directly as the engine speed; means for controlling said ow; means adapted to contain a control pressure developed by the first mentioned means and acting on the second mentioned means for inuencing the functioning thereof; and temperature responsive means for varying the quantity of fuel supplied to the engine.

6. The invention defined by claim 5 and including a manually controlled valve for modifying the control pressure.

7. The invention defined by 'claim 5 including manually controlled means for cutting olf the flow of fuel to the conduit.

8. The invention defined by claim 5 wherein there is means for 'cutting off the flow of fuel to the conduit; a valve for effecting modification of the control pressure; and a manually actuated lever adapted to alternately actuate the cut off means and said valve.

9. The invention defined by claim 5 including a passage by-passing the means for controlling the fuel flow; and means, including a valve, for controlling said passage, said means being so constructed and arranged as to be controlled by engine charging pressure and to temporarily effect opening of the valve upon an increase in said charging pressure.

10. In a fuel system for an internal combustion engine: a source of fuel; a conduit connecting said fuel source with the engine; means for creating a fuel pressure in and effecting a flow of fuel through said conduit, the quantity of which will vary directly as the engine speed; means for controlling said flow; means adapted to containa proportion of fuel to air delivered to the engine developed by the first mentioned means and acting on the second mentioned means for influencing the functioning thereof; a metering Jet in the conduit; means, including a valve, for varying the control pressure; and means responsive to a differential in fuel pressure upstream and downstream of said metering jet for controlling said valve.

11. In a fuellsystem for an internalcombustion engine: a source of fuel; a conduit connecting said fuel with the engine; means for creating a fuel pressure in and effecting a flow of fuel through said conduit, the quantity of which will vary directly as the engine speed; means for controlling said flow; means adapted to contain a control pressure developed by the first mentioned means and acting on the second mentioned means for influencing the functioning thereof; and means responsive to exhaust back pressure adapted to vary the control pressure.

12. A fuel system for an internal combustion engine comprising a conduit for supplying fuel to the engine; fuel metering means in said conduit; fuel flow control means posterior to the metering means; means, having an inlet and an outlet, for supplying fuel to said metering means at a pressure varying in accordance with engine speed; means for creating a pressure intermediate the pressure at said inlet and outlet; means for subjecting the fuel flow control means to the fluid pressure posterior to the metering means, and to the intermediate pressure acting in opposition to said uid pressure; means for varying the intermediate pressure, said means being responsive to engine charging pressure; and

manually controlled means for modifying the intermediate pressure.

13. A fuel system fox an internal combustion engine comprising a conduit for supplying fuel to the engine; fuel metering means in said conduit; fuel flow control means posterior to the metering means; means, having an inlet and an outlet, for supplying fuel to said metering means at a pressure greater than the inlet pressure by an amount substantially proportional to the square of engine speed; means for creating a pressure intermediate the pressures at said inlet and outlet; means for subjecting the fuel flow control means to the fluid pressure posterior to the metering means, and to the intermediate pressure acting in opposition to said fluid pressure; means for varying the intermediate pressure, said means being responsive to engine charging pressure; and manually controlled means for cutting off the flow through the conduit.

14. In a fuel system for an internal combustion engine: a conduit for supplying fuel to the engine; fuel metering means in said conduit; fuel flow control means posterior to the metering means; means, having an inlet and an outlet, for supplying fuel to said metering means at a pressure varying as a function of engine speed; means for creating a pressure intermediate the pressures at said inlet and outlet; means for sub- 13 to the engine; fuel metering means in said conduit; fuel flowl control means posterior to the metering means; means, having an inlet and an outlet, for supplying fuel to said metering means at Aa pressure greater than the inlet pressure by an amount substantially proportional to the square of engine speed; means for creating a pressure intermediate the pressures at said inlet and outlet; means for subjecting the fuel flow control means to the fluid pressure posterior to the metering means, and to the intermediate pressure acting in opposition to said fluid pressure; means for varying the intermediate pressure, said means being responsive to engine charging pressure; means for cutting off the flow of fuel through the conduit; means for modifylng the control pressure; and manually con` trolled means for actuating said cut off means and said modifying means.

16. In a fuel system for an internal combustion engine: a conduit for supplying fuel to the engine; fuel metering means in said conduit; fuel flow control means posterior to the metering means; means, having an inlet and an outlet, for supplying fuel to said metering means at a pressure greater than the inlet pressure by an amount substantially proportional to the square of engine speed; means for creating a pressure intermediate the pressures at said inlet and outlet; means for subjecting the fuel flow control means to the fluid pressure posterior to the metering means, and to the intermediate pressure acting in opposition to said fluid pressure; means for varying the intermediate pressure, said means being responsive to engine charging pressure; and a device in parallel with the metering means, for varying the supply of fuel to the engine, said device includin-g a valve responsive to fuel pressures upstream and downstream of the metering means.

17. The invention defined by claim 16 wherein said device is adapted to so control the flow of fuel to the engine as to increase the proportion of fuel to air at high engine output.

18. In a fuel system for an internal combustion engine: a conduit for supplying fueLto the engine; fuel metering means in said conduit; fuel flow control means posterior to the metering means; means, having an inlet and an outlet, for supplylng fuel to said metering means at a pressure greater Athan the inlet pressure by an amount substantially proportional to the square of engine speed; means for creating a pressure intermediate the pressures at said inlet and outlet; means for subjecting the fuel flow control means to the fluid pressure posterior to the metering means, and to the intermediate pressure acting in opposition to said fluid pressure; means for varying the intermediate pressure, said means being responsive to engine charging pressure; and means for effecting the variation in the intermediate pressure in accordance with engine back pressure.

19. In a fuel supply system for an internal combustion engine: a conduit for supplying fuel to the engine; a metering orifice in said conduit; a valve posterior to the orifice for controlling the flow of fuel posterior to said orifice; pump means for supplying fuel to the metering orifice at a pressure varying in accordance with engine speed; means for creating a control pressure; means for subjecting the valve to fuel pressure posterior to the orifice for urging said valve in one direction, and to said control pressure for urging the valve in the opposite direction; means, including a valve, for varying the proportion of fuel to air to the engine, said means being responsive to fuel 14 pressures upstream and downstream of the metering means; and means for modifying the `control pressure in accordance with engine back pressure.

20. A fuel supply system for an internal combustion engine comprising a conduit for supplying fuel to the engine; a metering jet in said conduit; a valve posterior to the -jet for controlling the flow of fuel downstream of said jet; pump means for supplying fuel to the metering jet at a pressure varying as a function of engine speed; means for creating a control pressure; means for subjecting the valve to fuel pressure posterior to the jet for urging said valve in one direction, and to said control pressure for urging the valve in the opposite direction; means for varying the proportion of fuel to air including a valve responsive to fuel pressures upstream and downstream of the metering means; and means for temporarily increasing the mixture richness, said means being responsive to engine charging pressure.

21. In a fuel supply system for a'n internal combustion engine: a conduit for supplying fuel to the engine; a metering jet in said conduit; a valve posterior to the jet for controlling the ow of fuel downstream of said jet; pump means for supplying fuel to the metering jet at a pressurevarying as a function of engine speed; means for creating a control pressure; means for subjecting the valve to fuel pressure downstream of the Jet for urging said valve in one direction, and to said control pressure for urging the valve in the opposite direction; means for varying the proportion of fuel to air including a valve responsive to fuel pressures upstream and downstream of the metering means; a by-pass about the metering jet; and a temperature responsive device for controlling said by-pass.

22. In a fuel supply system for an internal combustion engine: a conduit for supplying fuel to the engine; a metering jet in said conduit; a valve posterior to the jet for controlling the flow of fuel downstream of said jet; pump means for supplying fuel to the metering jet at a pressure varying as a function of engine speed; means for creating a control pressure; means for subjecting the valve to the downstream fuel pressure for urging said valve in one direction, and to said control pressure for urging the valve in the opposite direction; meansfor varying the proportion of fuel to air including a valve responsive to fuel pressures upstream and downstream of the metering means; and means, including a manually controlled valve, for varying the control pressure.

23. In a fuel supply system for an internal combustion engine: a conduit for supplying fuel to.

the engine; a metering jet in said conduit; a valve posterior to the jet for controlling the flow of fuel downstream of the jet; pump means for supplying fuel to the metering jet at a pressure varying as a function of engine speed; means for creating a control pressure; means for subjecting the valve to metered fuel pressure for urging said valve in one direction, and to said control pressure for urging the valve in the opposite direction; means, including a valve for varying the proportion of fuel to air, said means being responsive to fuel pressures upstream and downstream of the metering means; and manually actuated means for closing said first mentioned valve.

24. The invention defined by claim 23 and including a manually controlled valve for modifying the control pressure..

25. In a fuel supply system for an internal combustion engine: a conduit for supplying fuel to the engine; a metering jet in said conduit; a valve posterior to the jet for controlling the flow of fuel downstream of said jet; pump means for supplying fuel to the metering jet at a pressure varying as a function of engine speed; means for creating a control pressure; means for subjecting the valve to metered fue1 pressure for urging said valve in one direction, and to said control pressure for urging the valve in the opposite direction; means for varying the proportion of fuel to air including a v,alve responsive to fuel pressures upstream and downstream of the metering means; abypass about the metering jet; temperature responsive means for controlling said by-pass; a by-pass about said jet and rst mentioned valve; and means, including a valve, for controlling the second mentioned by-pass, said means being so constructed and arranged as to temporarily enrich the fuel mixture upon an increase in engine charging pressure.

26. In a fuel supply system for an internal combustion engine: a conduit for supplying fuel to the engine; a metering jet in said conduit; a valve posterior to the jet for controlling the flow of fuel downstream of said jet; pump means for supplying fuel to the metering jet at a pressure greater than the pump inlet pressure by an amount substantially proportional to the square of engine speed; means for creating a control pressure; means for subjecting the valve to metered fuel pressure for urging said valve in the opening direction, and to said control pressure for urging the valve in the closing direction; means, including a valve, for varying the proportion of fuel to air, said means being responsive to fuel pressures upstream and downstream of the metering means; a by-pass about said jet and flrst ment'oned valve; means for controlling said by-pass,

said means being responsive to engine charging pressure and so constructed and arranged as to temporarily supply an auxiliary charge of fuel upon the rise in said engine charging pressure; and means, including a manually controlled valve, for regulating the control pressure.

2'7. The invention defined by claim 26 and including manually actuated means for closing the first mentioned valve.

28. In a fuel supply system for an internal combustion engine: a conduit for supplying fuel to the engine; a metering jet in said conduit; a valve posterior to the jet for controlling the flow of fuel downstream of said jet; pump means for supplying fuel to the metering jet at a pressure varying as a function of engine speed; means for creating a control pressure; means for subjecting the valve to vmetered fuel pressure for urging said valve in 'me direction, and to said control pressure for urging the valve in the opposite direction; means for varying the proportion of fuel to air including a valve responsive to fuel pressures upstream and downstream of the metering means; a by-pass about the metering jet; a temperature responsive device for regulating the flow of fuel through said by-pass; and a manually controlled valve for modifying the control pressure.

29. The invention defined by claim 28 wherein there is a manually actuated plunger adapted to effect closing of the first mentioned valve.

30. In a fue1 supply system for an internal combustion engine: a conduit for supplying fuel to the engine; a metering jet in said conduit; a valve posterior to the jet for controlling the flow of fuel downstream of said jet; pump means for supplying fuel to the metering jet at a pressure greater than the pump inlet pressure by an amount substantially proportional to the square of engine speed; means for creating a fuel control pressure; means for subjecting the valve to fuel pressure downstream of the jet for urging same in the opening direction, and to said control pressure for urging the valve in the opposite direction; means responsive to engine charging pressure for varying the control pressure; a manually controlled valve adapted to modify said control pressure: manually controlled means adapted to effect closing of the first mentioned valve; a by-pass about the' metering jet; temperature responsive means controlling said by-pass; a second by-pass about said metering jet; means responsive to the pressures on opposite sides of the metering jet for controlling said second by-pass; a passage bypassing the metering jet and the first mentioned valve; and means, including a valve, for controlling said passage, said means being so constructed and arranged as to be subjected to engine charging pressure and to temporarily open said valve upon an increase in said engine charging pressure.

31. A fuel supply device for an engine having an induction passage comprising a conduit for delivering fuel to said induction passage; a centrifugal pump; a metering orifice; and a discharge valve, in series in said conduit; a lay-pass l around said pump having two restrictions therein to provide a pressure for regulating said discharge valve; and a manually actuated control valve for varying the effective capacity of one of said restrictions, thereby to vary said control pressure.

32. In a -fuel supply device for an engine having an induction passage: a source of fue1 at a substantially constant pressure; a conduit connecting said source with said induction passage; a centrifugal pump; a metering orifice; and a pressure responsive discharge valve, in series in said conduit arranged in that order; a by-pass around said pump having two restrictions therein to provide a pressure intermediate the pressure on either side of said pump for regulating said discharge valve; and a manually actuated control valve for varying the effective capacity of one of said restrictions, thereby to vary said control pressure.

33. In a fuel supply device for an engine having an induction passage: a source of fuel at a substantially constant pressure; a conduit connecting said source with said induction passage; a centrifugal pump; a metering orifice; and a pressure responsive discharge valve in series in said conduit; a by-pass around said pump to provide a pressure intermediate the pressure on either side of said pump for regulating said discharge valve, said by-pass being in communication with said conduit at three separate ports; a manually actuated valve for varying the flow of fue1 through one of said ports; and a uid pressure actuated valve for controlling the flow of fuel through another of said ports, therebyto vary said control pressure.

34. In a fuel supply device for an engine having an induction passage: a source of fuel at a substantially constant pressure; a conduit connecting said source with said induction passage; a centrifugal pump; a metering jet; and a pressure responsive discharge Valve, in series in said conduit arranged in that order; a fuel passageway with a restriction therein around saidmetering jet; a valve regulated in accordance with engine temperature for controlling the effective size of said restriction; a by-pass around said pump having two restrictions therein to provide a pressure intermediate the pressure on either side of said pump for regulating said discharge valve, said 17 by-pass being in communication with said conduit at three separate ports; a manually actuated valve for varying the flow of fuel through one of said ports; and a fluid actuated valve for controlling the flow of fuel through another of said ports.

35. A fuel supply system for an engine, comprising a conduit adapted to receive fuel under pressure from a source and to deliver the fuel to said engine, a means for varying the pressure of the fuel in said conduit in accordance with engine speed, a restriction in said conduit for metering the fuel delivered to said engine, and a manually regulated means communicating with the inlet and outlet sides of the rst mentioned means for controlling the metering head across said restriction.

36. A fuel supply system for an engine, comprising a conduit for delivering fuel to the engine, a means for supplying fuel to said conduit, a means for varying the pressure of the fuel in said conduit in accordance with engine speed, a restriction in said conduit posterior to the second mentioned means, and a manually regulated means communicating with the inlet and outlet sides of the second mentioned means for controlling the metering head across the restriction.

37. In a fuel system for an internal combustion engine: a source of fuel; a conduit connecting said source of fuel with the engine; means for creating a fuel pressure in and effecting a flow of fuel through said conduit, the quantity of which will vary directly as the engine speed; means for controlling said flow; a means for containing a control pressure developed by the first mentioned means and acting on the second mentioned means for influencing the functioning thereof; and a screw valve regulating the connection between the fuel under said first mentioned pressure and the fuel under the control pressure.

38. In a fuel system for an internal combustion engine: a conduit for supplying fuel to the engine; fuel metering means in said conduit; fuel flow control means posterior to the metering means; means having an inlet and an outlet, for supplying fuel to said metering means at a pressure varying in response to variations in engine speed; means for creating a pressure intermediate the pressures at said inlet and outlet; means for subjecting the fuel now control means to fluid pressure posterior to the metering means and to the intermediate pressure acting in opposition to said fluid pressure; and an acceleration device, controlled by manifold pressure, adapted to supply a supplemental quantity of fuel upon a rise in manifold pressure.

39. The invention defined by claim 38 wherein the acceleration device is also responsive to fuel pressure.

40. The invention defined by claim 38 wherein said acceleration device is responsive to the fuel pressure at said outlet for effecting a supply of acceleration fuel.

4l. The invention defined by claim 38 wherein the acceleration device comprises a valve; a diaphragm connected to the valve and subjected to the fuel pressure of said outlet for urging the valve in the opening direction; a second diaphragm providing a pair of chambers; a relatively large passage for one chamber and a relatively small passage for the other chamber, both of said passages being connected to a source of engine 18 charging pressure; and a spring in said other chamber urging the valve in a closing direction.

42. In a fuel system for an internal combustion engine: a source of fuel; a conduit connecting said source of fuel with the engine; means for effecting a flow of fuel through said conduit at a pressure greater than the inlet pressure by an amount substantially proportional to the square of engine speed; means for controlling said flow; means for containing a control pressure developed by the first-mentioned means and acting on the second mentioned means for influencing the functioning thereof; means, including a valve, for varying the control pressure, said means being responsive to engine charging pressure; and means responsive to engine charging pressure for supplying an additional quantity of fuel for acceleration purposes upon a rise in pressure in a low manifold pressure range.

43. An invention defined by claim 42 wherein the control pressure valve is actuated in a direction to effect mixture enrichment at high engine output.

44. In a control device for a fuel system having means for raising the fuel pressure above atmospheric pressure: a valve; a diaphragm connected with the valve; yielding means urging the valve in the closing direction; means for subjecting the diaphragm to the fuel pressure created by the pressure raising means, for urging the valve in the opening direction; and means for subjecting the other side of the diaphragm to engine charging pressure for urging the valve in the opening direction.

45. In a fuel control device for a fuel system having means for creating a fuel head proportional to the square of engine speed: a valve; a diaphragm connected with the valve and suby jected to the fuel pressure for urging said valve in the opening direction; yielding means for urging the valve in the closing direction; a second diaphragm operably connected with said yielding means and valve; and means for subjecting the opposite sides of said second diaphragm to engine charging pressure, said means being so constructed and arranged that a rise in said engine charging pressure will result in a faster rise on one side of the diaphragm than the other and effect a reduction in the spring force tending to close the valve.

46. The invention defined by claim 45 wherein there are chambers on opposite sides of the second diaphragm and there is a relatively large passage leading into one chamber and a relatively small passage leading into the other chamber whereby the pressure rise in the chamber having a large passage leading thereinto will be most rapid.

FREDERIK BARFOD. EMIL O. WIRTH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 35,146 Edson May 6, 1862 1,786,402 Russell Dec. 23, 1930 FOREIGN PATENTS Number Country Date 429,682 Great Britain June 4, 1935 523,895 Great Britain July 25, 1940 Certcate of @orrection Patent No. 2,456,604; December 14, 1948.

I FREDERIK BARFOD ET AL.

It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

'Column 4, line 34, for the Word dicharge read discharge; column 9, line 61, for responsibe read responsive; column 11, lines 74 and 75, claim 10, strike out proportion of fuel to air delivered to the engine and insert therefore control pressure; column 12, line 4, claim 10, strike out control pressure and insert therefor propor- .tion of fuel to air delivered to the engine; column 17, line 46, claim 38, after means,

second occurrence, insert e comme; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Oice. f-

Signed and sealed. this 31st dey of Moy, A. D. 1949.

PHY, @sie am# Uommsmer of Paen'te.