US1762357A - Fluid-pressure governor - Google Patents

Description

June 10, 1930.

WITNES H. F. SCHMIDT FLUID PRESSURE GOVERNOR Filed April 25, 1927 INVENTOR ATTORNEY Patented June 10, 1930 UNITED STATES FATE? HENRY F. SCHMIDT, OF LANSDOWNE, PENNSYLVANIA, ASSIGNOR T WESTINGHOUSE ELECTRIC 6t MANUFACTURING COMPANY, A CQRPORATION OF PENNSYLVANIA FLUID-PRESSURE GOVERNOR Application filed Apri 25,

My invention relates to a fluid pressure governing system, more particularly to a system for a prime mover which governs the admission of motive fluid thereto in accordance with fluid pressure developed by a Pitot tube and a rotating bowl carried by the turbine shaft, such fluid pressure varying with the speed oft-he shaft, and it has for its object to provide an accurate and reliable system 10 0f the character designated.

Another object is to provide a governing system having prompt governing action and ample fluid supply to move the admission valve rapidly in accordance with the governing pressure.

Fluid pressure governing systems have heretofore been used wherein the admission valve is operated by a spring-biased piston reciprocating in a cylinder. Fluid pressure varying with the speed of the turbine is developed by an impeller carried on the prime mover shaft and is applied to the valve-operating piston in opposition to the force of the spring. It necessary to supply a considerable quantity of fluid under pressure to the piston to actuate the valve, and. a substantial period of time is required to supply this volume of fluid.

In accordance with my invention, I provide a Pitot tube projecting into a rotating bowl carried by the prime mover and apply the pressure developed thereby to a pilot valve. The latter controls an operating piston which in turn actuates the admission valve. I also provide an impeller on said shaft for supplying ample fluid under pressure to the operating piston for operating the same upon movement of the pilot valve.

By providing a relay valve as the pressurercsponsive element, the latter may be made of small diameter and of small travel, as its only function is to open and close the ports leading to the operating piston. The governing pressure delivered by the Pitot tube is therefore not materially affected by displacement of fluid by the pressure-responsive element. By providing an independent source of fluid pressure for actuating the operating piston,

0 the governing pressure is not affected. A

1927. Serial N0. 186,383.

more rapid movement of the valve to its propor position is, therefore, obtained.

Apparatus exemplifying my invention is illustrated in the accompanying drawing, in which:

Fig. 1 shows diagrammatically and partly in section my novel governing system; and,

Fig. 2 is a sectional View as seen from the line Il -11 of Fig. 1.

Referring now to the drawing in detail, I show a bearing housing 10, enclosing the bearing 9 and the corresponding end portion of a rotor shaft 11, of a prime mover, for example, a steam turbine. Motive fluid for driving the turbine is admitted through a steam chest 12 and coi'itrolled by an admission valve 13.

A piston 14 og ierating in a cylinder 15 is operatively connected to the valve 13, as by a stem or rod 16. The piston 14!; is o iicrated by fluid pressure controlled by a relay 1?.

The relay 17 includes a cylinder or casing 18 and a pilot valve 19. The relay casing 18 has a high pressure fluid. inlet port 20 and fluid discharge port 2].. It also has ports 22 and. 23 co-imnunicating respectively with ports 24: and 25 at the upper and lower ends of the cylinder 15. The pilot valve 19 is provided with piston portions 2" and. 2,7 which cover the ports 22 and .23 when the valve 13 is at normal position. Piston portions 28 and 29 are provided at the ends of the pilot valve 19. The follow-up mechanism for returning the pilot valve 19 to its normal position, in which it closes the ports 22 and 2", en'ibodies a lever 30 pivoted at one end to a stationary member 31 and at the other end to the rod 16. Pivoted to the lever 30, preferably near the stationary member 31, is a stem projecting through the lower closed end of the cylinder18. A, tension spring 33 is connected at its upper end to the interior of the pilot valve 19 and at its lower end to the stem 32.

To provide governing fluid pressure, I secure a bowl or other vessel 10 on the shaft 11, preferably, as shown, at the end thereof. As shown, the bowl 10 comprises a peripheral side 4-1, a closed radial side 1-2 and a radial side f?) having a circular opening at the center thereof. The bowl 10 is adapted to con-V tain an annulus of liquid having a level correspending to the inner periphery of the wall 43. A litot tube 44 secured in the housing 10 projects into the bowl 40 near the outer.

periphery of the enclosed space. The end of the Pilot tube 44 extends circumferentially or tangentially as shown in Fig. 2.

Impeller means for developing fluid pres sure for operating the piston 14 are provided on the shaft 11, in this case being shown as vanes 45 mounted on the back of the radial wall An annular wall 46 covers the outer sides of the vanes 45. The casing 10 is provided with an annular chamber 47 around the outer periphery of the vanes 45 and communicating therewith. The casing 10 is further provided with an inwardly projecting wall 48 for enclosing the impeller 45 and has labyrinth packing 49 in the inner periphery thereof for preventing the escape of high pressure fluid from the space between members 46' and 48. Labyrinth packing 50 is also provided between the outer periphery of bowl 40 and the casing 10.

The Pitot tube 44 communicates with the relay cylinder 18 through a conduit or pipe 60, and, delivers the pressure developed therein to the pilot valve 19 against the tension of the spring 33. The pressure chamber .47 communicates through conduits 61 and 62 with the inlet port 20 of the relay 17. The conduit 61 also communicates with the inlet of an ejector 63, disposed below and receiv ing fluid from a reservoir 64. A conduit 65 leads from the discharge ports 21 of the relay 17 to the oil reservoir for returning to the latter the fluid discharge from the relay. A conduit 66 is also provided for draining fluid from the casing 10 which overflows from the bowl 40, and that which leaks by the packing elements 50.

A conduit 70 communicates with the discharge opening of the ejector 63 and also with the chamber or compartment 71 in which the impeller vanes 45 are disposed. A branch conduit 72 leads from the conduit 70 through the casing 10 into the interior of the bowl 40. The conduit 72 is preferably provided with a regulating valve 73. Another branch conduit 74, leading from the conduit 70, supplies fluid to the bearing 9 for lubrication. A drain conduit returns the fluid discharged from the bearing to the reservoir 64.

is applied to the pilot valve 19 in opposition I to the force exerted by the spring 33 and controls the movements of the pilot valve.

Upon an increase in speed of the shaft 11, the increased lluidpressurc raises the pilot valve 19, thereby placing the port in communication with the high pressure fluid delivered through port 20 and placing the port 23 in communication with the discharge port 21. Fluid under pressure from the impeller vanes 45 is then transmitted through conduits 61 and 62, andoorts 20 and 22 of the relay 17, to the port 24 of cylinder 15, and is applied to the upper side of piston 14, moving the latter in a direction to close the valve 13. The fluid in casin 15 below the piston 14 is discharged through port 25, and through ports 23 and 21 of the relay to conduit 65 and thence to the fluid reservoir As the rod 16 moves downwardly with piston 14 and valve 13, it

moves with it the lever 30. The stem 32 is,

therefore, moved downwardly and returns the pilot valve 19 to its normal posit-ion.

Upon a decrease in speed of the shaft 11 the pressure within. the Pitot tube 44 drops, resulting in a lowering of the pilot valve 19 by the spring 33. This places the port 23 in communication v 'th port 20 and high pressure fluid is adnr. ed through port to the casing 15 and applied to the lower side of piston 14, causing the latter to move upwardly in a direction to open the valve 13. The port 22 is placed in communication with discharge port 21 and releases the fluid from casing 15 in the upper side of piston 14 through the port The lever 30 is raised carrying the stem 32 upwardly with it until the pilot valve 19 is brought back to its normal position, closing the ports 22 and 23.

The ejector 63 supplies fluid at relatively low pressure to the chamber 71 to supply the impeller 45. The valve 73 is adjusted to permit a slight flow through conduit 72 to the interior of bowl 40 in order to insure a con stant level of fluid within the bowl 40. The fluid overflowing the wall 43 drains back to the reservoir 64 through the conduit 66. The low pressure fluid developed by the ejector 63 is also preferably used for lubricating the bearings and is transmitted from branch 74 of conduit 70.

From the above description, it will be seen that the pilot valve 19 may be made relatively small and designed to have but a short travel. The displacement of fluid used for governing iressure is slight and the gov erning pressure is not substantially affected by such movement. Inasmuch as a separate source of fluid pressure is provided for operating the piston 14, there is no disturbance of the governing pressure due to the use of fluid for operating the piston 14. it will also be apparent that I have provided a simple and compact apparatus for governing the prime mover. The only moving parts ill for generating fluid pressure are carried directly on the rotor shaft, and the liability of failure of oil pressure is therefore minimized.

While I have shown my invention in one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications, without departing from the spirit thereof, and I de sire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is:

1. In a governing system for a prime mover having a rotating shaft and an admission valve, the combination of a piston operating the admission valve, a pilot valve controlling the operating piston, a vessel carried by the shaft and adapted to contain an annular body of fluid, a Pitot tube projecting into said vessel, means for applying the pressure in said tube to said pilot valve for controlling the movement thereof, and impeller means carried by said vessel on the exterior thereof for developing a second fluid pressure for actuating the operating piston as determined by the pilot valve.

2. The combination with a prime mover having a rotor and an admission valve, of means for controlling the admission valve including a motor device, means providing motive fluid under pressure for actuation of the motor device, a pressure-responsive relay for controlling the admission and exhaust of motive fluid to the motor device, means connected to the rotor and providing an annular chamber for liquid, a Pitot tube arranged in the chamber and connected to the relay for controlling the operation of the latter, and means for supplying liquid to the annular chamber including an impeller pump which discharges liquid to the chamber, a reservoir located below the pump for receiving liquid discharged from the chamber, and an ejector motivated by liquid received from the discharge side of the pump for supplying motive and entrained liquid to the inlet of the pump.

3. The combination with a prime mover having a rotor and an admission valve, of means for controlling the admission valve including a motor device, a centrifugal pump having an impeller carried by the rotor for developing pressure of fluid to actuate the motor device, a pressure-responsive relay for controlling the admission and exhaust of motive fluid to the motor device, an annular bowl disposed adjacent to the impeller and carried by the rotor for providing an annular chamber for liquid, means including the impeller pump for supplying liquid to said bowl, and a Pitot tube arranged in the chamber and connected to the relay for controlling the operation of the latter.

at. The combination with a prime mover having a rotor shaft and an admission valve,

of a governing system therefor comprising means carried by the rotor shaft and providing an annular chamber for liquid, a Pitot tube projecting into said body of liquid and providing a liquid pressure varying as a function of the speed of rotation of the shaft, 2. motor device for actuating the admission valve, an impeller mounted on said shaft for supplying liquid pressure for actuating the motor device, means responsive to the variable fluid pressure in the Pitot tube for controlling the admission and exhaust of motive fluid to the motor device, and means including said impeller for supplying liquid to said chamber.

In testimony whereof, I have hereunto subscri lzoed my name this nineteenth day of April, 192

HENRY F. SCHMIDT.

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