US2678533A

US2678533A - Means for controlling the supply of liquid fuel to internal-combustion prime movers

Info

Publication number: US2678533A
Application number: US161511A
Authority: US
Inventors: Lawrence Owen Napier
Original assignee: Joseph Lucas Ltd
Current assignee: ZF International UK Ltd
Priority date: 1949-05-16
Filing date: 1950-05-12
Publication date: 1954-05-18
Anticipated expiration: 1971-05-18

Description

May 18, 1954 LEAD/NG- FROM 19 BLOWER FUEL O. N.-"LAWRENCE MEANS FOR CONTROLLING THE SUPPLY OF LIQUID TO INTERNAL-COMBUSTION PRIME MOVERS Filed May 12, 1950 CONNECTED 7b BLowE/e INLET 9 lag-3 com/5:711:

w BLOWER A O U TL E T Patented May 18, 1954 MEANS FOR CONTROLLING THE SUPPLY OF LIQUID FUEL TO INTERNAL-COMBUSTION PRIME MOVERS Owen Napier Lawrence, Dorridge, England, as-

signor to Joseph Lucas Limited, Birmingham,

England Application May 12, 1950, Serial No. 161,511

Claims priority, application Great Britain May 16, 1949 Claims.

This invention relates to means for controlling the supply of liquid fuel to internal combustion prime movers, such as jet-propulsion engines, gas turbines or the like, and to which air is supplied by a blower.

The object of the invention is to provide improved fuel regulating means of the kind which is responsive, at least in part, to blower-air pressure.

In the accompanying sheet of explanatory drawing:

Figure 1 is a part sectional view illustrating diagrammatically fuel regulating means according to the invention in association with a variable delivery fuel pump of the swash-plate type.

Figures 2 to 6 are similar sectional views illustrating respectively five modifications of the invention.

The variabl delivery fuel pump shown in Figure 1 is of well known form and comprises a rotary body part a in a casing b; a plurality of spring-loaded plungers c mounted in bores in and extending from one end of thebody part, an angularly adjustable swash plate d by which the plungers are actuated during rotation of the body part, a fuel inlet passage 6, and a fuel delivery passage j. The body part a is adapted to be driven in any convenient manner by the prime mover (not shown) to be supplied with fuel by the pump, the prime mover being supplied with air by a blower (also not shown).

Atone end of the pump casing b is a cylinder 9 having closed ends. Within the cylinder 9 is arranged a piston h loaded by a spring 2, and extending from one side of this piston and through one end of the cylinder is a rod which is connected to the swash plate (1. One end of the cylinder g is in free communication with the pump delivery passage f through a passage is. The other end of the cylinder g (which contain the spring 2) communicates with the pump delivery passage through a restricted passage m, and also communicates with a small vent n which at its outer end forms a seating for a closure member 0 on one end of a lever p in a chamber q. When the vent n is closed the piston h is moved by its loading spring i in the direction for causing the swash plate (1 to increase the pump output, and when the vent is open the piston is moved by fluid pressur in the direction for causing the swash plate to reduce the pump output. The lever p carrying the vent-closure member 0 i pivotally supported at a position between its ends by a partition r dividing the interior of the chamber q into two compartments s, z. The vent n is formed in the wall of the compartment .9 which is provided with an outlet u, and contains a spring 11 which acts on the lever 10 in the direction for closing the vent. The other compartment t is divided into two sub-compartments by a diaphragm w adapted to act on the lever p in the direction for opening the vent, and these two sub-compartments communicate respectively with adjacent ends of two passages ac, y. The other end of the passage as communicates with the pump delivery passage 1' at a position between the pump outlet and a chamber 2 through which fuel from the pump delivery passage can flow to the nozzles 2 of the prime mover, the fuel flow through this chamber being controlled by a slidably adjustable throttle valve 3 adapted to co-operate with a seating 4 in the chamber. The other end of the passage y communicates with the chamber a at the outlet side of the seating 6. Consequently, the pressure difference set up by the throttle valve 3 is communicated to the diaphragm to acting on the lever 10, and the movement of the vent-closure member 0 (which controls the output of the pump) depends on this pressure difference.

In carrying the invention into effect as shown in Figure 1, there is employed a stepped cylinder 5 which is closed at its ends, and in which are slidable two integral or interconnected pistons 6, "l of different diameters. At a position between the pistons 6, l the cylinder 5 is connected by a passage 8 to the throat Q of a Venturi duct Ill through which the air from the blower (not shown) is caused to flow in the direction of the arrow, this passage being connected to the throat at a position centrally between the ends of the throat. The end of the cylinder 5 at the outer side of the larger piston l is connected to the Venturi duct i t at the exit side of its threat 9 by a passage i l. The other end of the cylinder 5 is connected by passages i2, it to the Venturi duct ID at the approach side of its throat 9. The exit side of the duct ill leads to a region in which the pressure is low relative to the blower delivery pressure, for example it may be open to atmosphere.

Coaxially with the cylinder 5 is provided another cylinder M which contains a piston valve [5 connected to the pistons t, i. Near one end the valve cylinder I 2- is connected by the passage [3 to the Venturi duct is at the approach side of the throat 9, and also to a closed chamber it containing an evacuated and deformable capsule I! which is connected to and adapted to operate the throttle valve 3 above mentioned. Alternatively the capsule 11 may be utilized for actuating any other appropriate controlling member in a fuel supply system. At a position spaced from the passage t3 the valve cylinder lilis connected by another passage 19 to the part of the passage l'3 between the valve cylinder and the chamber I6, and also to the throat 9 of the Venturi duct ID at a position between the center and the approach end of the throat. If desired the pistons 6, I may be loaded by a spring 20 acting on the outer side of the larger piston l.

The arrangement is such that below a given ratio of air pressures actingv on the pistons 8, l", the piston valve l5 establishes communication between the capsule chamber 16 and the Venturi throat 9 through the medium of the passage I9 and a part, of the passage I3, and above the said ratio the piston valve establishes communication between the capsule chamber and the Venturi duct It at the approach side of its throat through the medium of the passage [3.

Since the exit side of the Venturi duct is is open to a low or atmospheric pressure region, the pressure in the throat 9 will always be a predetermined part or fraction of the blower pressure applied to the entrance side of th duct, and the throat pressure will consequently rise as the blower pressure rises. With the'priine mover at rest, the valve it will occupy the position shown in Figure 1 due to the action of the spring 2t,'with the capsule chamber it in communication with the throat, s through the passage 19. When the prime mover is started up, this condition is maintained since the blower pressure acting through the passage E2 on the left hand side of the small piston 6 i unable to overcome the force acting in the opposite direction due to the low pressure from the exit side of the duct it acting through the passage l 5 on the right hand side of the large piston I. When the prime mover attains a predetermined speed and the ratio between the blower pressure at the entrance to the duct Iii and the pressure in the exit of the duct is exceeds a given value, the preponderating pressure acting through the passage E3 on the left hand side of the small piston B will move the pistons and valve to the right, since the low pressure acting through the passage I l on the right hand side of the large piston '1 remains substantially constant. This change in the position of the valve it closes the passage [9 and opens the passage l3, thereby establishing communication between the full blower pressure at the entrance end of the duct Ill and the capsule chamber it, whereby the fuel controlling throttle 3 is actuated to increase the supply of fuel to th burners of the prime mover.

The mode of applying the various pressures to the pistons 6, l in order to obtain the required movement of the piston valve can be varied in a number of ways example of which are shown in Figures 2, S and 4.

In the example shown in Figure 2, the cylinder 5 is connected at a position between. the pistons 6, l to the Venturi duct it at the approach side of its throat 9 by a passage 2!. The end ofthe 7 cylinder 5 at the outer side of the larger piston l,

is connected by a passage 22 to the Venturi throat 9 at a position centrally between the ends of the throat. The other end of the cylinder 5 at the outer side of the smaller piston 6, is connected by a passage 23 to the Venturi duct i 6 at the exit side of its throat. Near one end the valve cylinder i4 is connected by a passage 24 to the capsule chamber above mentioned, and also to the Venturi throat 9 at a'position between the entranceend and the center of the throat. At a position spaced from the passage 24 the valve cylinder I4 is connected by a passage 25 to the passage 2I, and also to the passage 24 at a position between the valve cylinder and the capsule chamber. If desired the pistons 6, I may be loaded by a spring 26 acting on the outer side of the smaller piston 6. In this example the pistons and valve occupy the position shown in Figure 2 when the blower delivery pressure and consequently the speed of the prime mover is within the lower range, and upon the blower delivery pressure exceeding the predetermined magnitude the valve 1 5 is moved to the left.

Referring now to Figure 3, the cylinder 5 is connected" at a position between the pistons 6. I to theventuri duct it at the approach side of its throat 9by'

passages

21, 28. The end of the cylinder 5 at the outer side of the larger piston l is connected by a passage 29 to the Venturi duct [0 at the exit side of its throat 9. The other end of the cylinder 5 at the outer side of the smaller piston 5 is connected by a passage 36 to the Venturi throat 9 at a position centrally between theencls of the throat. Near one end the valve cylinder It is connected by the passage 23 to the capsule chamber above mentioned, and also the Venturi duct is at the approach side of its throat 9. At a position spaced from the passage 28 the valve cylinder it is connected by a passage 3! to the passage 28 at av position between the capsule chamber and the valve cylinder, and also to the Venturi throat G at a position between the center and the entrance end of the throat. The pistons E), i may be loaded by a spring 32 acting on the outer side Of the larger piston 1.

In the example shown in Figure 4, the cylinder 5 is connected at a position between the pistons ii, i to the Venturi duct it at the exit side of its throat 9 by a passage 33. The end of the cylinder 5 at the outer side of the larger piston l is connected by a passage 3 to the Venturi throat 9 at a position centrally between the ends of thethroat. I'he other end of the cylinder 5 at the outer side of the smaller piston E5 is connected by passages 35, 36 to the Venturi duct ii] at the approach side of its throat 9. Near one end the valve cylinder M is connected by a passage 31 to the capsule chamber above mentioned, and also to the Venturi throat 9 at a position between the center and the approach end of the throat. At a position spaced from the passage 31 the valve cylinder [dis connected by the passage 35 to the capsule chamber, and also to the Venturi duct In at the approach end of its throat 5. The pistonsv E, i may be loaded by a spring 33 acting on the outer side of the smaller piston &.

The operation of the examples shown in Figures 2 to 4 is similar to that of the example shown in Figure l. 7

Instead of employing a pair of integral or inter-- connected pistons arranged in a stepped cylinder as in the examples above described, I may employ a single piston 39 arranged in a cylinder 4i]. of. uniform bore, as shown in Figure 5, for actuating thepiston valve 55. In this example the valve cylinder I l is connected by a passage 31 tothe capsule chamber above mentioned, and also to the Venturi duct It at the approach end of the threat 9, At a position spaced from the. passage 37 the valve cylinder is is connected by a passage 36 to the capsule chamber, and also to the Venturi throats at a position between the center and the approach end of the throat. Also the end of the cylinder 59 adjacent to the valve cylinder. 14 is connected by a passage 4| to the Venturi throat 9 at a position centrally between the ends of the throat. Moreover, the other end of the cylinder 40 is connected by a passage 42 to the Venturi duct I!) at the exit side of its throat. The piston 39 may be loaded by a spring 43 acting on the side of the piston remote from the valve l5.

In all of the examples above described the positions at which the Venturi throat communicates with the associated passages may be varied depending on the blower pressure at which the piston valve is required to be actuated, and on the fraction of the blower pressure required to be initially exerted on the capsule.

Instead of employing an evacuated and deformable capsule as the fuel-controlling member in the examples above described, an equivalent diaphragm or piston may be used.

Further instead of employing a piston or pistons for actuating the valve as in the examples above described equivalent flexible diaphragms may be used. Thus, the piston shown in Figure 5 may be substituted by a diaphragm 44 as shown in Figure 6. This diaphragm 44 divides a chamber 45 into two compartments 46, 41, the compartment 46 being adapted for connection by a passage 48 to the inlet side of the blower (not shown), and the other compartment 4'! being adapted for connection by a passage 49 to the delivery side of the blower. The last mentioned compartment contains an evacuated and deformable capsule 50 which is connected at one end to the diaphragm 44 and at the other end to the adjacent wall of the chamber 45.

In operation the examples shown in Figures 5 and 6 are essentially similar to the examples shown in Figures 1 to 4.

By this invention the ratio of the fuel and air supplied to an internal combustion prime mover can be made to vary in a predetermined manner at different speeds of the prime mover.

The invention is not, however, limited to the examples above described, as subordinate details may be varied to suit different requirements.

Having described my invention what I claim as new and desire to secure by Letters Patent is:

1. Fuel regulating means for use with an internal combustion prime mover to which air is supplied by a blower driven from the prime mover comprising, in combination, means for controlling the rate of flow of fuel to the prime mover, a

member responsive to fluid pressure variations operatively connected to said means for actuating the same, a duct adapted to be connected at one end to the blower delivery and leading at its other end to a low pressure region such as atmosphere, said duct having therein flow restricting means such as a Venturi throat to create thereby in the duct by the flow of air from the blower therethrough a region at a pressure which is a predetermined and related fraction of the blower delivery pressure, a passage affording communication for air at blower delivery pressure to said fluid pressure responsive member, a second passage affording communication to said fluid pressure responsive member from said region in the duct in which the pressure is a related fraction of the blower delivery pressure, valve means controlling said passages and havingtwo positions for selectively opening one passage and closing the other, and means responsive to blower air delivery pressure for actuating said valve when said pressure exceeds a predetermined magnitude to close the second and open the first of said passages, and to close the first and open the second of said passages when the blower air delivery pressure is below said magnitude, whereby difierent ranges of actuating pressures are applied to the fuel controlling pressure responsive member according to whether the blower delivery pressure is above or below the said magnitude and thereby the ratio of fuel and air supplied to the prime mover is differently variable at different speeds thereof.

2. Fuel regulating means according to claim 1, in which the pressure responsive member which actuates the fuel control means is arranged to divide a chamber into two parts, one of which parts is evacuated, and the said first and second passages are in communication with the other part of said chamber.

3. Fuel regulating means according to claim 1, in which the said valve means comprises a slidable valve member and. the means responsive to blower air delivery pressure for actuating the said valve is situated in an enclosure provided with passages for admitting blower air pressure and air from a source at lower pressure so that said means is responsive to the difierence between said pressures.

4. Fuel regulating means according to claim 1, in which the said valve means comprises a slidable valve member and the means responsive to blower air pressure comprises a flexible diaphragm arranged to divide a chamber into two compartments having passage means for admitting air at blower delivery pressure to one of said compartments and for admitting air from a source at a lower pressure to the other of said compartments, and in which an evacuated anddeformable capsule situated in one of the compartments is connected at opposite ends respectively to the diaphragm and an end of the chamher so that the diaphragm is responsive to the difference between the air pressures acting on it and on the capsule.

5. Fuel regulating means according to claim 1, in which the said valve means comprises a slidable valve member and the means responsive to blower air delivery pressure for actuating the said valve is situated in an enclosure provided with passage means for admitting air at blower air pressure from one part of the said duct and for admitting air at a lower pressure from an other part of the said duct so that the difference between the air pressures at the said parts of the duct is transmitted to the pressure responsive means.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,382,625 Garretson Aug. 14, 1945 2,422,808 Stokes June 24, 1947 2,482,528 Wiegand et al Sept. 20, 1949 2,507,075 Wiegand May 9, 1950