US2657529A - Means for controlling the supply of liquid fuel to combustion prime movers - Google Patents

Description

o. N. LAWRENCE 2,657,529 MEANS FOR CONTROLLING THE SUPPLY OF' LIQUID y AFUEL TO COMBUSTION PRIME MOVERS Filed May 1'7. 1950 2 sheets-sheet 1 s Es Figi

NOV.`3, 1953 N, LAWRENCE 2,657,529

- O. 'MEANS'.-FOR CONTROLLING THE SUPPLY OF LIQUID FUEL TO COMBUSTION PRIME MOVERS Filed May 1'7, 1950 l 2 Sheets-Sheet 2 7'0 5 /ower' Ouf/ef @All/@w10 ence Patented Nov. 3, 1953 MEANS FOR CONTROLLING THE SUPPLY OF LIQUID FUEL s TO COMBUSTION PRIME MOVERS Owen Napier Lawrence, Dorridge, England, as-

signor to Joseph Lucas Limited, Birmingham,

England Application May 17, 1950, Serial No. 162,564 Claims priority, application Great Britain June 7, 1949 Claims.

This invention relates to means for controlling the supply of liquid fuel to an internal combus- 'tion prime mover, such as a jet-propulsion engine, gas turbine or the like, and to which air is supplied by a blower. f The object of the invention is to provide improved means whereby variation in the ratio of the rate of fuel and air supply can be elfected in response to variation of the blower delivery pressure.

In the accompanying sheets of explanatory drawings- Figure 1 is a part sectional View illustrating diagrammatically fuel controlling means in accordance with the invention applied to a variable delivery fuel pump of the swash plate type.

Figures 2 and 3 are similar views to Figure 1 illustrating respectively two modied forms of the invention. Y

Figures 4 and 5 are sectional views drawn to a' larger scale than Figure l and illustrating respectively two modied details.

The Variable delivery pump shown in Figure v1 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 the body part, an angularly adjustable swash plate d by which the plungers are actuated during rotation of the body part, a fuel inlet passage e, and a fuel dellivery passage f. 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). Y

At one end of the pump casing b is a cylinder g having closed ends. Within the cylinder g is arranged a piston h loaded by a spring i, and extending from one side of this piston and through one end of the cylinder is a rod i which is Aconnected to the swash plate d. One end of the cylinder y is in free communication with the pump delivery passage f through a passage k. The other end of the cylinder g (which contains the spring i) communicates with the pump delivery passage ,i through a restricted passage m, and also communicates with a small vent n which yat its outer end forms a seating for a valve o on one end of a lever p in a chamber q. The spring i is arranged to urge the piston h in a direction for moving the swash plate d to a position corresponding to maximum pump output. When the vent n is closed by the valve o on lever p the liquid fuel pressures on the two sides of the piston h will be approximately equalized and the piston will take up a position determined by the additional force exerted by the spring i. When the vent n is opened, liquid will leak away from the underside of the piston h and will not be replaced at an equal rate due to the restriction m, whereby the liquid pressure beneath the piston is reduced and the liquid pressure above the piston will cause it to move downwardly against the loading spring i, thereby displacing the swash plate d to reduce the pump output.

The delivery passage fris formed with an enlargement r through which fuel can flow to the nozzles s of the prime mover under the con'- trol of a valve t adapted to co-operate with an annular seating u in the enlargement. The extent of opening of the valve t depends in known manner upon the pump delivery pressure.

In carrying the invention into effect as shown in Figure 1, the valve lever p is adapted to be moved against the action of a loading spring 1J in the direction for opening the vent n by an evacuated and deformable capsule w, and also by a piston :12.

rlhe capsule w is arranged in a chamber z to which air delivered by the blower can `be admittedvthrough an inlet 2, and is adaptedk to exert pressure on the valve lever p through the medium of a stem 3 extending through one end of the chamber, the arrangement being such' that the pressure exerted by the capsule on the valve lever decreases with increase in the pressure of the blower-air. i

The piston :cis movable in a cylinder 4 under I the action of rfuel delivered by the pump to exert pressure on the valve lever 2J through the medium of a rod 5. One end of the cylinder 4 is connected by a passage 6 to a secondpassage l at a position between two restricted orifices 8, 9 in the second passage. At lone end the second passage l is in communication with the pump delivery passage f. The other end of the secondpassage 'l is open and is controlled by a valve l0 on one end of a lever Il, the latter being situated in a chamber l 2, and being loaded by a spring I3 in the direction for closing the valve. v Y Y The v alve lever H is movable in the direction for opening the valve il! by a diaphragm l :l which is adapted to act on the valve lever through the medium of a stem l5, and which divides a chamber it into two compartments Il, IS, the compartment i 'i being adapted for connectionby a passage I9 tothe inlet side of the blower, and the other compartment I8 being adapted for connection by a passage 2l! to the delivery side of the blower. 'I'he compartment I8 contains an evacuated and deformable capsule 2l which is connected ,at .one end. Hto the diaphragm. at the other end tothe adjacent wall of the chamber I6.

The arrangement is such that so long as the ratio of blower outlet and inlet pressures lies below a predetermined amount, the valve II) controlling the second passage '-I remains closed, and the vent-controlling valve o is then respon sive to the blower air pressure and the full @pressure of the fuel delivered by the pump. But when the ratio of blower outlet and inlet pressures exceeds the predetermined amount, .the Valve I controlling the second passage "I is opened, and the vent-controlling valve o 'is then subject to the blower air pressure and a fuel pressure lower than the delivery pressure lof vthe pump.

VThe .modication shown in Figure .2 differs from that shownV in Fig-ure 1 in the following respects:

'The pump deliverypassag-e 7 is controlled by a tfniottle 22 connectedto an evacuated and delforrnable caps-ule 23` in a chamber 24 to which .air delivered by the .blower can be admitted through an inlet 2.5, so that the throttle is responsive to blower air pressure. Also the pump .delivery passage -f 'is connected by a passage 2t at l I'flie exit ,side of. the vthrottle 22 to the charnber I2 containing the valve lever II above men tioned. Moreover, the Ychamber I2 and the part of `the above mentioned passage 1 between the restricted orifices '8., .9 are v`connected by passages 121,2:8-*to Voppositeends ofthe cylinder 4 containing the piston zr. Further, Hthe vent-valve lever Ap is'zmova-ble in the direction for opening the vent n 'solely `by the piston x. In .other respects the example shown in Figure l2 in similarto that shown in Figure l and is indi-cated by the Vsame `reference characters.

When `the 'valve It controlling 'the passage 'I is closed, the piston :v (and consequently ythe ventvalve lever \p) is subject to the full difference of the fuel pressures at opposite sides ofthe throttle 22. But when the valve -I-'II is open, the piston fr is subject to a lower difference of fuel pressure.

Thek .modifica-.tion :shown in Figure 3 differs from -that shown inl -Eigurey 2 in the following respects.:

The vent-valve lever Ap is connected to a pair of coaxial integral or interconnected pistons 30, -3fI of different diameters contained in a Kstepped cylinder 32. and the outer end of the smaller part x.of the :stepped cylinder 32 are `respectively connected by three passages 33, .34, 35 to a cylinder 36 rcontaining .a lslidable piston valve 31 which is connected to .the diaphragm I4. The cylinder 35 is .also connected by a pair of passages 3'8, 3B to the pump delivery passage f at opposite sides of the throttle 22. In other respects the example .shown in Figure .3 is similar to that shown in .Figure 2 and is indicated by the same reference characters..

The arrangement is such that in one position of the piston valve 31 the lower side of the larger piston `3l is exposed to the fuel pressure at the upstream side of the throttle 2.2 while the upper side of the smaller piston 3B is exposed to the fuel pressure at the downstream side of the throttle and in .another position of the piston valve the .smaller piston 3.0 is Iexposed at opposite sides respectively to the said pressures, both The Atwo -ends of the larger, Dart sides of the larger piston being at this time exposed to the pressure at the upstream side of the throttle.

In anyv of.. lthe examples above described the evacuated and deformable capsule 21 may be directly connected at its opposite ends respectively to the diaphragm I4 and the adjacent wall of the chamber IS or 4I as shown in Figure 4-o-r Figure 5. In the example shown in Figure 4the chamber I6 is of uniform diameter, and is provided with inlets I9, ZI) as previously described through which the opposite sides of .the diaphragm I4 are respectively exposible to the inlet andoutlet pressures of the blower. If, however, it is desired to avoid exposure of the capsule .ZI to the `delivery pressure of the blower, the diaphragm I4 may serve with another diaphragm 4E! to divide a chamber 4I into three compartments 42, 43, 44 as shown in Figure 5. The compartment 44 is smaller than the other compartments, and contains the capsule 2I, Athe latter being 'connected at its opposite ends respectively to the diaphragm I4 and the adja cent end wall of the chamber 4I. Also this compartment 44 and the compartment 42 are situated at vopposite ends of the chamber 4I, and are adapted for connection by passages 45 to the inlet side of the blower. Moreover, the compartment 43, which is situated between the other compartments 42, 44, is of the same dameter as the compartment v42., and is adapted for connection by a passage 45 to the outlet side of the blower.

By this invention .the ratio of the A.fuel and .air 4supplied to the prime mover is variable in response to predetermined changes in the blower an' pressure.

The invention is not, however, limited to the examples described as subordinate construetional details may be varied to suit different requirements. Thus diaphragms may be used in.- stead of pistons or deformable capsules, and -vice versa, for actuating the various valves.

Having .thus described my invention, what I Y cla-im as :new and desire to secure by Letters Patent is;

v1 For use in controllingy the supply of fuel from Va pump to a prime mover which receives lair from a blower, a controlling means comprising, in combination, a viii-iid pressure operable device `for regulating the rate Yat'wlrich fuel iss-upplied to the prime mover, a first -valve controlling said device, a second device operable by fuel pressure delivered by the pump for `actuating the said valve to `reduce the 4fuel vsuppljy asv the Ypump pressure rises, a first means respon-sive to :the pressure of air from the blower for varying vvthe effect of tthe Vsecond device on the first valve to increase the fuel supply when the blower pressure increases and vice versa, a second valve for Yvarying .the action .of `the fuel pressure from -the pump .on .the secondfdevice, and a second means responsive to the blower .inlet and outlet air pressures for vactuating the second valve to reduce the fuel pressure acting on the second device and thereby increase .the supply of fuel when .the ratio O f 'blower .outlet and inlet pressure exceeds a predetermined ratio, and vice versa.

2. A controlling means according to claim 1, comprising a passage `through which fuel can now under the control of the second valve, two flow restricting means in said passage, and a connection between a point .intermediate said restricting means l.and one .end .of the second device whereby the Ipressure at said point is effective on the said second device.

3. A controlling means according to claim 1, comprising a delivery passage through which liquid fuel from the pump can flow, a throttle responsive to blower-air pressure for controlling fuel flow through said delivery passage and forming a part of the rst means, a second passage communicating with the said delivery passage at the entrance side of the throttle and controlled by the second valve. two flow restricting means in the second passage, a connection between a point intermediate lsaid restricting means and one end of the second device whereby the pressure at said point is -effective on said second device, and a connection between the other end of the second device and the delivery passage at the exit side of the throttle.

4. A controlling means according to claim l, comprising a stepped cylinder forming a part of the second device, a pair of coaxial pistons of different diameters slidable in the cylinder and forming another part of the second device, a

second cylinder containing the second valve, the o latter having the form of a piston valve, three passages connecting diierent parts of the stepped cylinder to the second cylinder, a delivery passage through which liquid fuel from the pump can now, a throttle responsive to blower-air pressure for controlling the fuel ilow through the delivery passage and forming a part of the iirst means, and additional passages connecting the second cylinder to the delivery passage at opposite sides of the throttle.

l5. A control means according to claim 1, in which the means for actuating the second valve comprise, in combination, at least one diaphragm arranged to divide a chamber into parts, connectlons between said parts and the inlet and outlet respectively of the blower, and an evacuated and deformable -capsule in the chamber and connected to the diaphragm.

OWEN NAPIER LAWRENCE.

References Cited in the file of this patent UNITED STATES vPATENTS

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