US2702560A - Speed and acceleration responsive governor for power plants - Google Patents

Description

Feb. 22, 1955 W. 5. BOBIER, JR

SPEED AND ACCELERATION RESPONSIVE GOVERNOR FOR POWER PLANTS Filed Oct. 30, 1947 INVENTOR.

United States Patetft SPEED AND ACCELERATION RESPONSIVE GOVERNOR FOR POWER PLANTS Wilfred S. Bobier, Jr., Grosse Pointe, Mich assignmto The objector this invention is to restrict the fuel supply to an ordinary gas turbine at any preselected speed.

Another ob ect is to prevent excessive speed atter acceleratlon (overrun), thus preventing hunting.

A further ob ect is to regulate the fuel supply during deceleration so as to avoio stalling (underrunmng).

lug. l shows diagrammatically the general arrangement of this invention.

rig. 2 is a partial cross-section elevation on plane 22 of hg. l. in the figures, is the fuel entrance, 12 is a venturi in the fuel entrance, 14 is the fuel control valve, 16 is a spring urging the valve 14 to the right, that is, the direction of WLllCh the valve 14 opens. 17 is the fuel restriction m which the valve 14 is moved. 60 is the fuel outlet. 20 18 the manually operated lever which engages with the cap 22, inside of which the spring 16 is located. The lever 20 is moved by the cam 21. A similar cap 24, on the end of the valve 14, forms the right hand seat for the compression spring 16. Diaphragm 28 engages with the right hand end of valve 14. A tension spring 30 connects diaphragm 28 with diaphragm 32. The chamber 102, to the right hand side of diaphragm 32, is connected through passage 34 to the throat of the venturi 12. 36 1s the high pressure passage connecting the chamber 100, between diaphragm 28 and 32, with the passage 40 which is connected to the fuel entrance 10. A gas turbine (not shown) is operated with the fuel discharged through fuel outlet 60. A rotating element 46 is driven by the gas turbine.

An annular chamber 44 surrounds the rotating element 46. An overriding element 48, connected by a flexible rod 50 which acts as a spring and is connected to rorating element 46, permits relative motion of the overriding element 48 with reference to the driver 46.

A rectangular port 52, in element 48, engages with a low pressure restriction 56 in driver 46 (Fig. 2) during acceleration and with high pressure port 54 (Fig. 2) in driver 46 during deceleration.

A restriction 55, in driver 46, connects the chamber 88, through the servomotor valve 90, with the passage 94.

The fuel as it passes the fuel restriction 17 drops in pressure. This low pressure fuel is discharged through passage 60 to the turbine.

A passage 62 is connected to a passage 64, in the center of the rotating element 46 and to port 57 through a restriction. A spring 66 and a cylindrical valve 68 is also provided so that the pressure in the entrance 10 is held approximately at a constant pressure above the pressure in passage 60.

' The relief valve 71, loaded with a spring 72, limits the pressure in fuel entrance 10 to about 600 pounds per square inch. The passages 70 and 74 lead back to the entrance of the fuel supply pump, not shown.

A minimum fuel flow adjustment 76 is provided for low speed operation, and also to prevent stalling during a manually called for deceleration. The adjusting screw 7 8.regulates the speed increase that takes place after the governor has become operative and before the valve 14 has ceased to move. This is called the reset or droop adjustment.

The rotating element 46 contains the centrifugal weight 80 which is thrown out by centrifugal force to corripress a spring82. The chamber 84 communicates with the high pressure fluid in annular space 44. On the inner face of the Weight 80 is a cylindrical chamber 88 and the pressure in this chamber 88 is regulated by the ice servomotor valve 90. The hollow valve 90 cuts oi the flow of high pressure along the passage 92, that is, when valve 90 is in the position shown. When valve 90 rises, under influence of spring 82 and because of too low a pressure in chamber 88, the fluid under pressure is admitted into the chamber 88 and the spring 82 is compressed. Again when the valve 90 descends, due to the centrifugal force compressing the spring 82 and the pressure in chamber 88 being too high, then the pressure of the fluid in the chamber 88 is lowered because the chamber 88 is placed in communication with the passage 64 by the upper edge of the valve 90. The pressure in chamber 88 is transmitted through the passage 94, to the passage 96, to the chamber 98, and to the left of the diaphragm 28. The chamber 100, between the diaphragms 28 and 32, as already stated, is at the high pressure of the fuel entrance 10. The chamber 102, to the right of the diaphragm 32, is at the pressure established in the throat of the venturi 12.

OPERATION Assume steady running (neither acceleration nor deceleration) then a state of equilibrium will exist in which the speed of the element 46 will be such that the pressure in the chamber 88 plus the centrifugal effect of weight 80 just balances spring 82 plus fluid pressure in entrance 10. The pressure in chamber 88 will be intermediate between the pressure in the fuel entrance 10 and the pressure in the fuel exit 60.

Then pressure in chamber 88 is transmitted through the hollow valve 90, through the restriction 55, through the slot 52, through the passage 94, through the pipe 96 to the chamber 98, which is to the left of the diaphragm 28. The pressure in the chamber 98, plus spring 16, just balances the pressure in the chamber 102.

The efiect of high pressure fluid in chamber 100 is to stretch spring 30. The pressure in chamber 100 exceeds the pressure in chamber 102 by the velocity effect of the flow through the venturi 12, as modified by the droop adjustment 78.

As the governor acts to restrict fuel flow the flow through venturi 12 falls so that the pressure in chamber 102 increases so that the speed is reduced more rapidly because of the existence of the venturi 12.

Acceleration that the speed selected by the rotation of the cam 21 is not exceeded appreciably.

Deceleration During deceleration the element 46 decreases in rotation of velocity and the element 48 continues, thus bringing the slot 52 to line up with the deceleration ports 54. This admits high pressure from the passage 92, to the passage 94, down the pipe 96 to the chamber 98. This high pressure admitted to the chamber 98 delays the movement of the valve 14 to the left so that the fuel is cut off at a less rapid rate than would otherwise be the case.

What I claim is:

1. A centrifugal governor, a source of fluid under high pressure, a second source of fluid under a lower pressure, said governor being adapted to reduce the high fluid pressure to an intermediate value so that the difference between the high and intermediate pressures varies as the square of the revolutions per minute comprising, a rotating mass, a radial cylinder therein, a.

weighted piston sliding in said cylinder, a passage admitting high pressure fluid to the outer end of the cylinder, intake and discharge ports for'the inner end of said cylinder, said ports connected to said high and low pressure sources, a servomotor valve moved by and with said weighted piston adapted to control said ports so (sec as to connect said high pressure fluid source to the inner end of the cylinder asthe piston travels radially inwards and to connect said low pressure fluid source with the inner end of said cylinder when the piston moves outwards to establish an intermediate pressure value within the inner end of said. cylinder whereby the pressure acfing on the inner face of the piston is lower than the high pressure acting on the outer face of the piston by an amount which varies substantially withv the centrifugal force exerted by said rotating piston, and control means responsive to said pressure difference.

2; A device asset forth in claim 1, including an overriding device comprising. a. second rotating mass flexibly connected to the first. rotating mass so as to rotate one way relative to the. first mass during deceleration and the other way during acceleration, a port connected. to. the low pressure fluid source and carried by the first rotating mass, at second port communicating with the inner end. of said cylinder and carried. by said second rotating mass, saidlow pressure port being located adjacent the said second port so as to be opened to establish. communication between the: intermediate pressure existing in the inner end of said cylinder and said low pressure source by a rotative movement of the second rotating mass relative to the first rotating mass when the first rotating' mass is moved ahead of the second rotatingmass during acceleration so as to decrease the intermediate pressure existing in the inner end of said cylinder whereby to increase the operative pressure difference between the high and low pressure fluid sources, to prevent overspeeding, a third port connected to the high pressure fluid source carried by the first rotating mass, said high pressure port being located adjacent the said second port so as to be opened to establish communication between the intermediate pressure existing in the inner end of the cylinder and said high pressure source by a rotating movement of the second rotating. mass relative to the first rotating mass when the first rotating mass is slowed down so as to increase the intermediate pressure value existing in the inner end of said cylinder whereby to decrease the operative pressure diflerence so as to prevent stalling during deceleration.

3. A centrifugal governonasource of fluid under high pressure, a second source under low pressure, said governor being adapted to provide an intermediate pressure that varies directly with the square of revolutions per minute comprising a rotating mass, a radial cylinder therein, a weighted piston sliding in said cylinder, ports connecting said high and low pressure fluid sources to the inner end of said cylinder to establish an intermediate pressure value within the inner end of said cylinder, a passage admitting high pressure fluid to the outer endpf said cylinder, a servomotor valve moved by and with said weighted piston and connected to control said ports.

said high pressure port being so located as to be opened by an inward movement of the piston and said low pressure port being so located as to be opened by an outward movement of the piston to maintain a pressure diflerance between the two ends of the cylinder to oppose and balance the centrifugal force of said weighted piston, control means responsive to said pressure difference, an overriding device comprising a second rotating mass flexibly connected to the first rotating mass so as to rotate one Way relatively to the first mass during deceleration and the other way during acceleration, a port connected to the lowpressure fluid and carried by the first rotating mass. a second port communicating with the inner end of said cylinder and carried by said second rotating mass, said low pressure port in said first rotating mass being located adjacent the second port so as to be opened to communicate with the intermediate pressure by a 1'0- tating movement of the second rotating mass relative to the first when the first rotating mass is moved ahead of the second rotating mass wherein communication with the low pressure port is established only during accelera' tion so as to increase the operative pressure difference between the hi h and low pressure fluid sources to prevent oversoeeding, a third port connected to the high pressure fluid source and carried by the first rotatingmass, said high pressusre port in said first rotating mass being located adjacent the second port so as tov be opened to communicate with the intermediate pressure by a 1'0- tating movement of the second rotating mass relative to the first when the first rotating mass is slowed up where,

in communication with the second port is established only during deceleration so as to decrease the operative pres sure difference between the high and low pressure fluid sources so as to prevent stalling during deceleration.

4. A governing mechanism comprising a source of fluid under high pressure, a fluid outlet, a restriction therein, a cylindrical pressure relief valve including connections whereby said valve is subjected on the opening side to the fiuid pressure and on the closing side to the pressure downstream of said restriction, a yielding load on said valve to establish a comparatively constant pressure difference across said restriction, a regulating valve in said restriction, a centrifugal governor controlling said regulating valve comprising a rotating mass, a radial cylindrical passage therein, a weighted piston in said passage, a passage admitting high pressure fluid to the outer end of said cylinder, a servomotor valve movable by and with said piston, two ports controlled by said servomotor valve, one of said ports communicating with the low pressure downstream of said restriction, the other with the high pressure source, said ports being connected to the inner end of said cylinder, said high pressure port. being so located as to be opened by an inward movement of' the piston and said low pressure port being so located so as to be opened by an outward movement-of the piston so as to establish an intermediate pressure and thereby establish a pressure difference between the two ends of the cylinder to balance the centrifugal force acting on said piston, a chamber, a movable wall therein, passages connecting said chamber with the two ends of said cylinder so that the same pressure difference is established on the two sides of said movable wall, yieldable means adapted to move the regulating valve to the open position, and a connection from the movable wall to the regulating valve to move said valve in the closing. position.

5. A device as set forth in claim 4 in which there is av second rotating mass elastically connected to the first rotating mass, a port carried by the second rotating mass, two ports carried by the first rotating mass on opposite sides of the port in said second rotating mass, one connected to the high pressure source. and one connected to the lower pressure source, the hi h pressure source port being put in communication with the port of the second rotating mass during deceleration and the low pressure source port being put in communication with the port of the second rotating mass during acceleration, and a passage connecting said port in said second rotating mass to that side of said movable wall which is subject to the intermediate pressure existing in the inner end of said cylinder.

6. A device as set forth in claim 4 in which there is a second rotating mass elasticallv connected to the first rotating mass. a port carried by the second rotating, mass, two ports carried by the first rotatin mass on onposite sides of the port in said second rotating mass, one connected to the high pressusre source, and one. connected to the lower pressure source, the hi h pressure source port being out in communication with the port. of' the second rotating mass during deceleration and the low pressure source port being put in communication with, the port of the second rotating mass during acceleration. and a passa e connecting said port in said second rotating mass to that side of said movable wall which is subiect to the intermediate pressure existing inthe inner end of said cvlinder, and manually movable means for var ing the yieldable load on said regulating valve to varv the speed at which the centrifugal governor becomes operative.

References Cited in the file of this patent UNITED STATES PATENTS l,8ll.850 Huff June 30, I931 2.155.247 Warner Apr. 18. 1939 2.358.99 olet Sept. 26, 1944 2,407,982 Hanna Sept. 24,, 1946 2,564,127 Orr Aug. 14. 1951 2,612,944 Orr Oct. 7, 1952

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