US1620528A - Governing mechanism for elastic-fluid turbines - Google Patents

Description

March 8 9 1927. p w. R. EMMET GOVERNING MECHANISM FOR ELASTIC FLUID TURBINES Filed May 8, 1923 Inventor William L.R.Emmet His Attorney Patented Mu. 8,1927.

UNITED 'STATES PATENT OFFICE.

WILLIAM I4. R. EKMET, OF SCHENECTADY, NEW YORK, ASSIGNOB TO om ELIG- TBIC COMPANY, A CORPORATION 01' NEW YORK.

GOVERNING MECHANISM FOR ELASTIC-FLUID TUBBIN'ES.

Application filed my a, 1923. Serial 110. 837,584.

The present invention relates to governing mechanism for elastic fluid turbines and while it embodies certain features of a broader character which are applicable to I elastic fluid turbines generally, as to certain aspects it relates more particularly to elastic fluid turbines utilizing as motive fluid a substance of high boiling oint, such as mercur for example,- such tur ines being used in a 10 system of the character of that disclosed and claimed in my Patent No. 1,167,158, granted January 4,1916.

The object of my invention is to provide an improved governing mechanism, and for 1 a consideration of what I believe to be novel and my invention, attention is directed to the accompanyin description and the claims appended t ereto.

In the drawing Fig. 1 is a diagrammatic view, partly in section, of a governing mechanism embodying my invention, and Fig. 2 is a detail sectional view on a larger scale.

Referring to the drawing, 5 indicates a shaft on which is mounted a turbine rotor or wheel 6 which drives the armature of a generator 7. Elastic. fluid is supplied to the turbine wheel through an admission conduit 8 and exhausts from it directly into a condenser, the casing of the condenser being indicated at 9. Elastic fluid is supplied to conduit 8 through a valve casing 10 and inlet pipe 11. The conduit 8, valve casing 10' and pipe- 11 are shown on an enlarged scale as compared to the turbine 'rotor and generator for purposes of illustration. It will be understood, of course, that conduit 8 conveys elastic fluid to suitable nozzles (not shown) which direct the elastic fluid to the buckets of the turbine rotor.

In valve casing 10 are two valves A and B comprising valve seats 12 and 13 with which valve members 14 and 15 cooperate. The valve seats are separated from each other by a wall 16 so that the two valves are in series as regards thefiow of elastic fluid, the flow being first throu h valve A and then through valve B. tem 17 of valve A projects through a guide 18 into a casing 19 in which is a packing in the form of a distendable diaphragm structure 20 which, while it permits movement of the Y valve, positively .preventsleakage. A portion of the valve stem indicated at 21 may closed.

with advantage be formed of a tube filled with concrete which serves to cut down the heat conduction through the stem. Connected to the lower end of casing 19 is'a cylinder 22 in which is a piston 23 provided with a rod 24 connected to valve stem 17. Between the upper surface of piston 23 and the top of cylinder 22 is a spring 25 which opposes movement of piston 23in a direction to open valve A. In cylinder 22 below piston 23 is an opening 26 through which fluid is admitted to and discharged from cylinder 22 for actuating piston 23. Mounted adjacent cylinder 22 is a pilot valve casing 27 provided with an inlet opening 28 and a discharge opening 29. In the pilot valve casing are ports 30 which connect inlet opening 28 to cylinder opening 26 by way of conduits 31 and 32 and also ports 33 which connect opening 26 to discharge opening 29 by way of conduits 34 and 35. The pilot valve stem 36 is provided with valve members 37 which cooperate with ports 30 and valve members 38 which cooperate with ports 33, the arrangement being such that when valve members 38 are in closed position valve members 37 are in open position and vice versa. Inlet opening 28 may be connected to any suitable source of fluid pressure supply such as the force feed lubricating system for the turbine, for example, and discharge opening 29 may convey fluid away to any suitable point. The amount of opening of valve A is limited by a stop nut 39 on the lower end of piston rod 24.

Connected to the outer end of pilot valve stem 36 is an armature 40 whlch moves between fixed stops, here indicated as the fixed abutment 41 on the one hand and the faces of the poles of an electromagnet 42 on the other hand. When armature 40 is against the poles of the electromagnet, ports 33 are closed and ports 30 are open (this being the position of the parts in the drawing), while when armature 40 is against stops 41, orts 33 are open and orts 30 are t 43 is a spring whicii biases armature 40 to a position against stops 41.

Electromagnet 42 is connected by lead wires 44 and 45 to a pair of contacts 46 one of which is stationary and the other movable, the latter being fastened to one arm of a lever 47 pivoted at 48. In the circuit is a source of electrical potential 49 and a holding magnet 50. On one end of lever 47 is an armature 51 which is presented to the pole face of magnet 50. At 52 isan adjustable spring which acts on lever 47 to move it in a direction to separate contacts 46. In the present instance spring 52 is located between an adjustable wing nut 53 and an end of lever 47 the nut being screwed onto the end of a pin 54 which'is fixed to a stationary casing 55 and projects loosely through the lever and spring. On the end of shaft 5 is a centrifugal governor comprising leaf springs 56 which at one end are fixed to the shaft and at the other end are connected to a sliding sleeve 57 guided on a-spindle 58. On springs 56 are governor weights 59. Surrounding spindle 58- is a spring 60 which opposes iaxial movement of sleeve 57 by weights 59. On the outer end of sleeve 57 is a pin 61 which engages lever 47 at a point between spring 52 and fulcrum 48.

It will thus be seen that governor spring 60 acts in a direction to oppose spring 52.

The operation of the arrangement so far described is as follows:

Assume that the turbine is running at normal speed and that the parts are in the positions shown in the drawing, valve A be ing held fully open by fluid pressure beneath piston 23 and contacts 46 being closed. If now the speed increases, speed governor weights 59 will be thrown outwardly by centrifugal force pulling sleeve 57 toward the left against the action of spring 60. This will unbalance the pressures on lever 47 whereupon spring 52 will turn the lever on its pivot and separate contacts 46 thus opening the circuit of electromagnet 42 and permitting spring 43 to reverse the position of the pilot valve. This closes ports 30 shutting off the supply of actuating fluid to cylinder 22 and opens ports 33 to permit fluid to escape from beneath piston 23. Spring 25 then forces piston 23 downward moving valve members 14 toward closed position. 'As soon as valve members 14 begin to move toward closed position, the sup-- ply of elastic fluid to the turbine is decreased and hence the speed. -As the Speed decreases governor weights 59 move inward v thus permitting spring 60 to force sleeve 57 toward the right and moving lever 47 against the action of spring 52 to again bring contacts 46 in engagement and close v the circuit on electromagnet'42. Electromagnet 42, being again .energized, pulls i to move valve members 14 in a direction to open the valve. The valve will then continue to open until the speed again increases above normal when the cycle of operation just described will be repeated. Except at suchtimes as when the valve is fully open, the governing mechanism gives to the valve definitely periodic pushes or impulses tending to open the valve, the valve being there must be a certain definite change in speed before the unbalance between springs 52 and 60 becomes great enough for spring 52 to move lever 47 to separate the contacts 46. As soon as they are separated, however, the magnet is deenergized so that the contacts are quickly and definitely separated.

This general form of governing and the mechanism for carrying itv out is not claimed in this application as it forms the subject matter of my copending application Serial No. 637,563, filed of even date herewith.

For operating the valve 13 I utilize an ar- The rangement in all respects similar to that used in connection with ,valve' 'A, except that a different form of speed governor is provided, and in the drawing the same reference numerals with the exponent a added are applied to corresponding parts' in so far as is required for an understanding of the structure. Inthis casethe speed governor comprises a disk 65 which is connected to lever 47 and moves ina cylinder 66. The diskfits the .cylinder loosely and is subjected on its under surface to a fluid pressure proportional to the speed of the turbine. In the present instance this fluid pressure is air pressure taken from an impeller 67 driven by the turbine shaft which lmpeller serves also to create a flow of air for ventilating the generator. Such an impeller will create a pressure'within the end shieldof the generator proportional to the speed. The-end shield of the generator is connected to cylinder 66 by a conduit 68. Springs 52 and 60* are so adjusted rela tively to each other that as long as the turbine speed remains below a predetermined value, the air pressure conveyed from impeller 67 through conduit 68 to the underside of disk 65 will be insulficient to move the disk. to separate contacts 46*. When the predetermined speed is exceeded, however, the air pressure will move the disk to separate contacts 46* and effect operation of valve B in the manner already explained in connection with valve A. It will be understood, of course,.that any suitable form of pressure-responsive device may be used, disk and cylinder 66'being only one example.

The governing mechanisms :for valves A. and B may be set so that one operates at a slightly higher speed than the other, the one set for the higher speed then serving as a sort of emergency valve, that is a valve which comes into action in case the valve set for the lower speed fails to function. Either may be set for the higher speed although preferably I so set the governing mechanism for valve B. I also utilize valve B as a hand controlled valve and to this end piston rod 24 is extended outside cylinder 22 and is provided with a threaded portion on which is mounted a hand wheel 69. By turning hand wheel 69 down against the end of cylinder 22, valve B can be forced to closed position and will be held closed until the hand wheel is turned in the opposite direction when the oil pressure can again open the valve. Valve B may be closed manually when the turbine is stopped and be gradually opened when the tur ine is started up.

. Also by adjusting hand wheel 69 to any intermediate position the maximum amount valve B can be opened can be regulated.

Connecting inlet conduit 11 to condenser 9 is a by-pass conduit 70 controlled by two valves 71 and 72 arranged in parallel so that when either valve opens elastic fluid can flow from conduit 11 directly to the condenser, by-passing valves A and B and theturbine rotor. Valves 71 and 72 are arranged side by side in a valve casing 73 and normally cover openings 74 and 75 through which the interior of the valve casing is connected to conduit 11. The connection of conduit 70 to valve casing 73 is indicated at 76.

Referring now to valve 71, its stem 77 passes through a stufiing box in the form of an extensible diaphragm 78 and is connected to the piston 79 of a fluid actuated motor, the cylinder of which is indicated at 80 and the ilot valve at 81. 82 indicates the inlet con uit to the pilot valve, 83 the discharge conduit, and 84 the conduit connection to cylinder 80. In the pilot valve casing is a sleeve 85 connected to piston 79 and provided with openings 86, 87 and 88 which cooperate with valve members 89 and 90 on pilot valve stem 91. Stem 91 is connected to one end of a lever 92 pivoted on a stationary arm 94. The other end of lever 92 is connected by a rod 95 to one endv of a lever 96 pivoted on the end ofa post 97 fixed to a casin 98. The upper end of casing 98 is closed y a head 99 on which is mounted a cylinder 100 which communicates with conduit 11 through an opening 101. In cylinder 100 is a piston 102 having a stem 103 connected to lever 96'. Movement of piston 102 is opposed by a spring 104 which at one end engages the piston and at the other rests on a cross piec 105 carried by bolts 106. By turning the nuts on bolts 106, spring 104 can be adjusted.

At 107' is a packing for piston 102 in the form of a distensible diaphragm.

As long as the pressure in admission conduit 11 is below that for which spring 104; is set, the parts stand in the positions shown in the drawing,'valve 71 being held closed by fluid pressure on piston 79 admitted by way of inlet conduit 82, openings 86 and 87 and connecting opening 84. The fluid pressure supplied through conduit 82 may be taken from any suitable source, such as the force feed lubricating system, for example. When the pressure in conduit 11 increases to a value above that for which spring 104 is set, piston 102 will be forced downward an amount proportionate to the excess pressure and this will move lever 96 downward, and through rod 95 and lever 92 raise the pilot valve stem so that valve member 89 covers ports 86, and valve member 90 uncovers ports 88, the arrangement being such that ports 86 are covered just in advance of the uncovering of ports 88. This (uts oil the fluid pressure supply to cylinder 80 and con nects the cylinder to discharge conduit 83 by way of conduit 84 and openings 87 and 88 thus relieving the pressure on piston 79 whereupon the elastic fluid pressure in conduit 11 will force valve 71 oil its seat. As soon as valve 71'moves, pilot valve sleeve 85 moves upward bringing openings 86 and 88 in line with valve members 89 and 90, thus cutting off further discharge of fluid from cylinder 80. If valve 71 overtravels, openings 86 will be uncovered thus admitting fluid pressure to cylinder 80 to move valve 71 toward its seat until openings 86 are again covered. It will thus be seen that for each position of piston or movable abutment 102 there is a definite valve opening for valve 71. As soon as valve 71 opens elastic fluid is by-passed through conduit 7 0 directly to condenser 9 thereby relieving the pressure in conduit 11.

Extending axially through pilot valve stem 91 is a passage 108 which serves to connect the space below valve member 89 to outlet conduit 83 by way of the additional openings 109 in sleeve 85. This serves to balance the pilot valve stem and to take care of leakage past valve member 84. Additional openings 109 serve also to provide additioal discharge area from cylinder 80 in case of excessive travel of the pilot valve, a thing which may occur in case the pressure in conduit 11 were to build up faster llif) than piston 79 was able to follow. At 110 drawing have the same reference numerals,

' -with the exponent a added, applied thereto. the description given inv connection with valve 71. Valve 72 is in the nature of an additional safety valve. Valves 71 and 72 maybe set to open at the same pressure or one may be set to open at a pressure slightly higher than the other. If piston 102 should fail to function at the pressure for which it is set, further increase in pressure will effect the opening of valves 71 and 72 directly by the pressure acting on their exposed surfaces.

Conduit 11 conveys elastic fluid from a boiler so that valves 71 and 72 form in substance safety valves for the boiler. By using in connection with valves 71 and 72 a by-pass conduit connected to the condenser, any elastic fluid blown off through such valves is not lost. This is a matterof importance when the elastic fluid is a fluid such as mercury vapor for example, whlch 1s relatively costly. In a system such as that disclosed in my above referred to patent, the condenser 9 functions also as a boiler for a. liquid of lower boiling point than that of the liquid from which the elastic fluid used in turbine wheel 6 is generated, the elastic fluid generated in the condenser boiler being utilized in another turbine. With the abovedescribed arrangement in case turbine wheel 6 goes out of commission or is shut down, elastic fluid can still be supplied to the condenser, if desired, to still generate other elastic fluid therein.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the a pparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States, 1s:

1. In combination, an elastic fluid turbine, a conduit for supplying elastic fluid thereto, a plurality of control valves in said conduit arranged in series with each other, a separate Its operation will be understood from' fluid-actuated motor for eachsvalve, and

separate speed-responsive means for controlling each motor.

2. In combination an elastic fluid turbine,

3; In a turbo-generator set, the combination of a turbine, a generator driven thereby, a ventilating impeller for the generator, a valve controlling the admission of elastic fluid to the turbine, amotor for operating said -va1ve, a reversible controlling means for said motor, and means responsive to the pressure created by said ventilating fan for periodically reversing said controlling means.

4. In a turbo-generator set, the combination of a turbine, a generator driven thereby. a ventilating impeller for the generator, a valve controlling the admission of elastic fluid to the turbine, a motor for operating said valve, controlling means for the motor which has two positions, one effecting movement of the motor to cause opening movement of the controlling valve and the other closing movement, an electromagnetic means for moving said controlling means, and governor means responsive to the pressure created by said impeller for controlling said electromagnetic means.

5. In a turbo-generator set, the combination of a turbine, a generator driven thereby, a ventilating impeller for the generator, a valve controlling the admission of elastic fluid to the turbine, a motor for operating said valve, controlling means for the motor which has two positions, one effecting movement of the motor to cause opening movement of the controlling valve and the other closing movement, an electromagnetic means for moving said controlling means, an electric circuit for said electromagnetic means, governor means responsive to the pressure created by said impeller for interrupting said electric circuit, and a holding magnet in said circuit which serves to insure a definite speed change between circuit interruptions.

In witness whereof, I'have hereunto set my hand this 7th day of May, 1923.

WILLIAM L. R. EMMET.

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