US2538605A

US2538605A - Speed and barometric responsive fuel control for gas turbines

Info

Publication number: US2538605A
Application number: US582266A
Authority: US
Inventors: Stanley M Udale
Original assignee: Individual
Current assignee: Individual
Priority date: 1945-03-12
Filing date: 1945-03-12
Publication date: 1951-01-16
Anticipated expiration: 1968-01-16

Description

Jan. 1, 191 s. M. UDALE SPEED AND BAROMETRIC RESP ONSIVE FUEL CONTROL FOR GAS TURBINES Flled March 12, 1945 EHNEN WNQR v Patented Jan. 16, 1951 UNITED STATES PAT Stanley M. Udale, Detroit, Mich., assignor to George M. Holley and Earl Holley Application March 12, 1945, Serial No. 582,266

3 Claims.

The object of this invention is to control the fuel supply of an engine by the density of the air and the speed of the engine. is installed on an airplane engine and if the airplane is dived, the increase in air density during the dive causes the engine to overspeed, and it is desirable therefore to restrict the fuel supply temporarily during the acceleration period and to allow the fuel supply to gradually increase to the desired amount after the plane has leveled off and the dive is over.

The figure shows diagrammatically the essential elements of my invention.

In the figure, l is'the fuel entrance, II is the fuel exit to the engine, not shown, I2 is an engine-driven-pump, which delivers each revolution an amount determined by the position of the control lever I3, [4 is a lever connected at one end to a liquid pressure responsive servomotor piston l5 and at the other end to the engine speed responsive piston l6.

An altitude or barometric element I'I moves the servomotor valve I8. An engine-driven pump I9 circulates lubricating oil past a temperature responsive heating element 20. When viscosity is high and temperature low, element 20 operates so that the effect of viscosity is negligible because of the electric heat available when the temperature is low.

The oil under pressure from pump I9 is conveyed through a passage 40 to cylinder 22 above speed responsive piston l6. An opening 23 in piston I6 allows oil to flow past a needle 25 in outlet 24. The needle 25 is controlled by lever 26, which is moved by the servomotor piston l5. An inlet 2'! into cylinder 28 above the piston I5 leads from the oil pressure passage 2| into cylinder 28. A passage 29 admits oil under pressure beneath the piston I5 from the passage 2|.

An outlet passage 30 delivers the oil back to the reservoir 42 from the central recess portion of the piston I 5 and also delivers the oil flowing past the needle valve 25 from the cylinder 22, which flows through the opening 23 and past the piston IS.

The pressure generated by the pump I9 is determined by thethe restriction 33. The oil under pressure in chamber 22 compresses a spring 3|, which supports piston I6. A stop 32 limits the upward travel of the piston I6.

Operation Assume that the plane driven by the gas turbine is in a dive, then the elements I! will be compressed by the increase in atmospheric pres- If such a device sure. Then the valve I8 will descend, and oil will escape through 29 from below the piston I5 past the valve I8 and then through passage 30 back to the reservoir 42. The pressure in chamber 22 therefore falls and the spring 3| raises the piston IE to stop 32. Hence, one end of the lever i4 rises and fuel discharge from pump I2 is decreased. However, simultaneously the piston I5 descends and the other end of lever I4 descends, which moves the lever I3 down so as to increase the discharge from the pump I2 and thus the effect of the piston I6 rising is cancelled out so that actually lever I3 does not more very much during a dive.

When acceleration is over and when equilibrium is reached, the valve I8 assumes the neutral position in which it is shown because the piston I5 descends as far as the valve I8 descends.

Then the escape of oil through piston I5 ceases. I

The pressure in 22 then increases and the piston I6 leaves the stop 32 until the pressure of spring 3I plus pressure below piston I6 equals the pressure above the piston I6. The position of the valve 25 determines the pressure below the piston I6. Meanwhile the valve 25 has been opened somewhat by the descent of the piston I5; hence, the flow through orifice 23 has increased and the pressure drop through orifice 23 has increased so that the piston IB descends. Hence, the effect of speed is more pronounced at sea level than it is at altitude. Hence, at sea level and at high speed, the speed effect of pump I9 ass sts the barometric device I! in increasing the rate of discharge per revolut on of the pump l2 to a maximum at maximum speed.

This device is particularly adapted to control the fuel supply to a gas turbine in which the turbine drives the o l pump I9 and the fuel pump I2 at speed proportional to the speed of the turbine. Gas turbines are particularly susceptible to excessive speeds.

At low speeds, the pressure generated by pump I9 is so low because of the comparatively large size of the restriction 33 that the spring 3i presses the piston I6 against the. stop 32; hence, at low speeds the barometric element I1 is the only control for the lever I3.

The fuel outlet II is shown enter ng the combustion chamber M of a gas turbine 50. The drive shaft 41 of the gas turbine is shown driving a bevel gear 43, which drives a gear connected to a shaft 45 which drives a variable stroke pump 46, of any well known type, in which there may be reciprocating pistons which engage with an inclined plate 48. The position of this plate 48 3 may be moved by the pump control lever I3 to vary the pump discharge in a well known manner. A similar gear and shaft 44, also driven by the shaft 1, drives the oil pump l9.

What I claim is:

1. In a speed density fuel supply, an engine speed responsive oil pump, a servomotor piston connected to said oil pump, a barometric responsive means, a. servomotor valve connected thereto and adapted to control said servomotor piston, an engine speed responsive piston, a cylinder therefor, a passage leading from said cylinder and connected to said engine speed responsive oil pump, aspring supporting said speed responsive piston and opposing the pressure generated by said pump, a fuel supply pump of the positive displacement type, a control lever therefor, a link, one end connected to the servomotor piston, the other end to the other piston,

means connecting said control lever to said link whereby the control lever is moved both by the servomotor piston in response to liquid pressure changes and by the other piston in response to changes in engine speed.

2. A device as set forth in claim 1 in which there is a restricted opening from one side of the speed responsive piston to the other, to modify the pressure on the said latter piston, a return passage from the low pressure side of said latter piston to the inlet side of the speed responsive 90 oil pump, a second restriction in said passage, a valve controlling said second restriction, pressure responsive means connected to said last named valve, barometric responsive means controlling said pressure responsive means so that an increase'in altitude closes said last named valve.

3. A device as set forth in claim 1 in which there is a restricted bypass in said cylinder around said speed responsive piston and a restricted outlet from the low pressure side of said cylinder and a valve therein, said last named valve being controlled by said barometric means whereby at high altitudes the valve is moved towards the closed position.

STANLEY M. UDALE.

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

349,209 Great Britain May 28, 1931