US2489214A

US2489214A - Fuel supply system

Info

Publication number: US2489214A
Application number: US600756A
Authority: US
Inventors: Barfod Frederik
Original assignee: Bendix Aviation Corp
Current assignee: Bendix Aviation Corp
Priority date: 1945-06-21
Filing date: 1945-06-21
Publication date: 1949-11-22
Anticipated expiration: 1966-11-22

Description

1949 F. BARIFOD 2 4mm FUEL SUPPLY SYSTEM Filed June 21, 1945 am am H2.

G9 G7 f\/ 76 INVENTOR.

zaoezm BARFOD BY ATTORNEY Patented Nov. 22, 1949 FUEL SUPPLY SYSTEM Frederik Barfod, South Bend, Ind., assignor to Bendix Aviation Corporation, South Bend, hat, a corporation of Delaware Application June 21, 1945, Serial No. 600,756

13 Claims. (Cl. 123-119) 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 such as, for example engine speed and engine 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.

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 drawing. 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 figure, which is a diagrammatic view of a fuel system embodying the present invention, there is shown an induction passage in having an air inlet l2, and a mixture outlet l4 connected to the intake manifiold it of an internal combustion engine, not shown, or to a supercharger inlet, should a supercharger be used, the induction passage It being controlled by a throttle valve it. A supercharger might alternately be connected to the inlet I! or devices of this character might be connected to both the inlet l2 and the outlet I4. Liquid fuel is supplied by a pump, indicated generally at 20, which may be operated by the engine, or by any other suitable means,

and iscapable 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 through a valve port 12 which communicates with a chamber ll connected with a conduit 36 leading to an impeller inlet chamber 46 of a pump, indicated generally at ll. The pressure of fuel in the conduit 36 is 2 substantially the same as that in chamber 34 and said pressure will be hereinafter referred to as the inlet pressure or pressure A.

The pump 41, as shown, is of the centrifugal type which includes an impeller 43 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 its R. P. M., said pump 41 being adapted to build up an outlet pressure which provides the metering head for the system. a

The outlet of pump 41 is connected by fuel conduits 52 and 53 with a chamber 5t in a fuel outlet control device indicated generally at 55. A metering restriction or jet 56 is provided between the conduits 52 and 53, the pressure of fuel or metering head in said conduit 52 being hereinafter referred to as pressure B. Also, as the fuel pressure in chamber 54 is at all times substantially the same as that in the passage 53 posterior to the jet 56, said pressure in chamber 54 and passage 53 will be hereinafter referred to as pressure C 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 80 through cross passages 6| in a tip portion 82 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 fuel emulsion is discharged from an annular groove 66 between the shoulder at the base of said tip portion 62 and the adjacent end of nozzle 60. The outlet for the chamber 54 is provided with a fitting Bl having a bore within which a flat sided or fluted valve 68 is slidably guided, said valve having a conical tip 89 cooperating with a valve seat 10 of a port II 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 a diaphragm 12. As shown, the attached valve end is riveted over at 13 and a washer-like spring retainer cup 14 is attached to the diaphragm on the side opposite chamber 54. The spring retainer ll provides means for retaining the adjacent end of a spring 16 disposed in a chamber ll within a housing 80. The spring is adapted to react between the retainer 14 and a second retainer 82 carried by a screw 84 and urges the valve 66 in the closing direction, said valve normally being closed when the engine is inoperative. The effective force of the spring is adjustable by reason of the screw 84 which is threadably received in an opening in the casing provided therefor. An atmospheric vent 06 is provided for the chamber 16.

The valve port 32 is controlled by a valve 60 having a stem 82 secured to a diaphragm 94 which forms one wall of the inlet chamber 34. The diaphragm 94 also forms a wall of a chamber 96 formed in a housing 96. A spring I00 is disposed in the chamber 66, reacting between a spring retainer I02 secured to the diaphragm and aspring retainer I04 disposed on a screw I06 threadably received in an opening in a boss I08 of the housing 60. A lock nut IIO may be provided on the screw I06 for retaining same in adiusted positions. Chamber 96 is also vented to atmosphere by means'of a vent II2.

Means for varying the effective size of orifice 56 comprises a valve II4 controlled by a suction responsive device indicated generally at H6. The valve H4 is connected to or formed integral with a valve stem II8 slidable in a guide I20, said stem II6 being connected at its outer end to a plate I22 forming one wall of a sealed expansible bellows I24 located in a chamber I25 formed by a casing I26 which is supported on the body I20 of the device by screws, not shown, or any other suitable well known means. The casing is subjected to engine charging pressure by means of a lconduit I30 which communicates with said casing adjacent the lower portion thereof, so as to draw :off any fuel which may seep past the stem H8,

I 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 I I4 will be normally closed when the pressure in the casing I26 is at its highest operating value.

Operation During normal operation fuel is supplied under ,pressure to the inlet 46 of the centrifugal pump 41 by means such as the fuel pump 20 although other means may also be employed to supply fuel to said inlet 46. Fuel received by pump 41 .is discharged under an increased pressure into passage 52 from which it flows through metering orifice 56 to conduit 53 and chamber 54, past valve 68 which is opened by the pressure of fuel in .chamber '54 acting on diaphragm I2, into conduit 58, and thence to the fuel delivery nozzle 60 or other fuel discharge means.

Normally the spring I00 is adjusted to maintain a predetermined fuel pressure, pressure A,

,, in chamber 34 and conduit 36. I Due to the inherent characteristics of the centrifugal pump 41, the pressure B at the outlet of pump 41 will be greater than the pump inlet During operation, with the valve H4 in a paltlally open position, fuel at pressure B will now through the calibrated restriction 66 into passage 52 and chamber 04.

Preferably, but not necessarily, the spring 10 is adjusted to permit the valve 60 to be opened by a fuel pressure C in chamber 54 somewhat less than pressure A, for a purpose to be hereinafter described. Normally, except for considerations hereinafter explained, the metered fuel pressure C of the fuel in chamber 54, will be maintained equal to pressure A. In the event pressure C should tend to exceed pressure A the valve 60 will tend to open to allow the escape of additional fuel to the nozzle and consequent lowering of pressure 0, and the reverse action will occur if C tends to be less than A. It should be noted that the above mentioned tendencies pressure A 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.

of pressure C to vary from the normal will be temporary and will be generally momentary. Also normally pressure C will be maintained substantially the same or greater than pressure A.

As is generally known, the quantity of fuel which will flow through a given size metering orifice such as metering jet 56 will vary in proportion to the square root of the differential in pressures B and C 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 II4 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 described in U. S. Patent No.-

. 2,456,604 issued to Wirth and Barfod on December cause bellows I24 to partially collapse whereupon valve II4 will move in a direction to increase the effective area of the calibrated restriction 66.

Upon increase in the effective area of orifice 56, pressure B will be reduced and pressure C increased. As a consequence the valve 66 will open to permit discharge of fuel to the engine at a greater rate such that the pressure C will be accordingly reduced to again equal pressure A, but fuel then is delivered through orifices 66 and II at a greater rate to compensate for the increase in air flow which instigated the change in the area of orifice 56.

A number of advantages are obtained by the present invention among which are the maintenance of pressure throughout the system thereby eliminating the formation of vapor therein and the provision of a device. which. at alltimes has ample metering head and pressures to properly control the operation of the various parts.

By properly contouring valve II4, the effective area of orifice 56.. 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 the proper shaping of the contour of valve II. It said valve 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.

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 opened by a pressure C Somewhat.

less than pressure A. Then at low engine charging pressures, corresponding to idle operation, the arrangement is of material effect in producing a relatively large increase in fuel fiow, thereby providing the desired rich mixture at idle. However at high engine charging 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 56, 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, or other changes might be made without departing from the principles of the invention and I contemplate the use of any such arrangements properly failing within the scope of the subjoined claims.

I claim:

1. A fuel feeding device for an internal combustion engine, comprising a conduit for supplying fuel to the engine; fuel metering means in said conduit; rotatable means, for supplying fuel to said metering means at a pressure varying in accordance with engine speed; means for supplying fuel to the inlet of said rotatable means at a substantially constant pressure; fuel control means, including a valve for said conduit posterior to the metering means, so constructed and arranged that the metered fuel pressure normally is maintained substantially at the same pressure as the inlet fuel pressure; and means for increasing the effective area of the metering means upon a rise in charging pressure.

2. A fuel feeding device for an internal combustion engine, comprising a conduit for supplying fuel to the engine; a metering jet in said conduit; a regulating valve posterior to the metering jet for controlling the flow of metered fuel; a pressure creating means for supplying fuel to the metering jet at a pressure varying in response to variations in engine speed; means for varying the effective area of the metering jet; and means for controlling the jet varying means in accordance with engine charging pressure.

' 3. A fuel feeding device for an internal complying fuel to the engine; a metering restriction in said conduit; a valve in said conduit posterior to said restriction; a diaphragm connected with said valve; pressure creating means having an inlet, and an outlet supplying fuel to, said conduit anterior to the metering restriction at a pressure varying in an amount substantially proportional to the square of engine speed; means for subjecting the diaphragm to fluid pressure posterior to the restriction for urging the diaphragm in the valve opening direction; and means for varying the effective area of the metering restriction.

4. In a fuel supply system for an internal combustion engine having an intake manifold controlled by a throttle: a conduit for supplying fuel to the manifold; a metering jet in said conduit; a valve in the conduit posterior to the jet; a fluid pump having an inlet, and an outlet supplying fuel to the conduit anterior to the jet at a pressure varying in an amount substantially proportional to the square of engine speed; I a source of fuel, at a substantially constant pressure, connected to the inlet; means for subjecting the valve to the metered fuel pressure for urging the valve in the opening direction; yielding means urging the valve in the closing direction, said means being so calibrated as to normally maintain the metered fuel at a pressure substantially the same as the pressure of fuel supplied to the inlet; and means responsive to manifold pressure posterior to the throttle for varying the effective area of the metering jet.

5. In a fuel supply system for an internal combustion engine: a conduit; means for sup plying fuel 'to said conduit at a substantially constant pressure; a metering restriction in said conduit; pressure creating means having an inlet receiving fuel from the first mentioned means and an outlet supplying fuel to'the metering means at a pressure varying in an amount substantially proportional to the square of engine speed; and means subjected to metered fuel pressure, tending to maintain metered fuel at substantially the same pressure as the first mentioned pressure.

6. The invention defined by claim 5 wherein there is means for temporarily varying the metered fuel pressure.

7. The invention defined by claim 5 wherein there is means for momentarily modifying the metered fuel pressure.

8. The invention defined by claim 5 wherein there is means, responsive to an engine variable, for varying the effective area of the metering restriction.

9. The invention defined by claim 5 wherein there is means responsive to engine charging pressure for varying theeffective area of the metering restriction.

10. In a fuel supply system for an internal combustion engine: a conduit for conveying fuel to the engine; means for supplying fuel to the conduit at a substantially constant pressure; a normally open valve in said conduit; a diaphragm connected to the valve and subjected to fuel pressure posterior thereto. said fuel pressure urging the valve in the closing direction; yielding means urging the valve in the opening direction; pressure creating means posterior to the valve and adapted to effect a flow of fuel therethrough, the quantity of which will vary directly as the engine speed; a metering restriction posterior to the pressure creating means; a

normally closed valve posterior to the metering restriction; a diaphragm connected to the valve and subjected to metered fuel pressure for urging the valve in the opening direction; and yielding means urging the valve in the closing direction.

11. The invention defined by claim 10 wherein the yielding means are so calibrated that the metered fuel pressure and the pressure of fuel supplied to the pressure creating means tend to be maintained normally at substantially the same value.

12. The invention defined by claim 10 wherein the yielding means are so calibrated and arranged that the metered fuel pressure is normally maintained at substantially the same value as the pressure of fuel supplied to the pressure creating means, and the idling mixture is enriched atengine idling speeds.

13. The invention defined by claim 10 wherein there is means for varying the eflective area of the metering restriction and said means is controlled by engine charging pressure.

- FREDERIK BARFOD.

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

UNITED STATES PATENTS