US1976659A - Governing mechanism for elastic fluid engines - Google Patents

Description

Get. 9, 1934.. E. D. DICKINSON 1,976,659

GOVERNING XECHANISM FOR ELASTIC FLUID ENGiNES I Filed May 3, 1934 Inventor: Edgar D. Dickinson, 6.19 by.

His Actorhg.

re ented-a; 9, 1934 UNITED" STATES wwwwas i GOVERNING nmcnamsn ms -msrrc rum). enemas Edgar D. Dickinaon, Beverly, Mass), asaignor to General Electric Company, a

New York cerporation or Application May 3, i934, 723,758

' .'-zomms..(cl.zs4-4) I end of the latter is connected to the stem- 15.01 M

The present inventionrelates tov governing mechanisms for regulating a control valve or this correction takes place slowly sothat if a large load, say full load, is suddenly taken'ofi the machine the speed will increase in accordance with this instantaneous broad regulation.

sudden increase 01 'speed may operate the emerzo gency governor and trip the machine off the line.

The object of myinvention is to provide an improved construction and arrangement of the type of governing mechanism referred to above whereby the control valvemor valves are moved rapidly towards closing position in response to sudden changes of load, thereby preventing the turbine unit being tripped oil by the emergency trip valve.

For a consideration of what I believe to be novel and my invention, attention is directed to the following description and the claims appended thereto in connection with the accompanying drawing which forms a part of my specification.

'The single figure-,0! the drawing shows a gov-f erning mechanism embodying 'my invention in connection with an elastic fluid'turbine. The

mechanism may be considered as comprising three,

essential elements: First, a motor and a control member for the motor actuated bya speed governor forming the parts of any ordinary speed governing mechanism; second, mea'nsQ-ior correcting the regulation of such ordinary speed governing mechanism in order to obtain zero regulation, that. is, constant speed at 'any load, or,.

if desired, positive or negative regulation; and

third, means provided in accorda'n'ce with my in- 'venti'on to suddenly change 3 the regulation dur- 0 ing pre-emergency conditions. Referring now more specifically-to the 81"? rangement indicatedin the drawing, a turbine 10 has a control valve 11 for controlling the admission of elastic fluid thereto. 'This val ve has a stem 12 connected to a fulcrumed level- 13 which in turn is connected by a link 14 'to the rights h hand end of a follow-up lever 14, Theleit-hand Thisa hydraulic motor 16 having a p1st'on'17 fastened to' the stem and biased in downward direction I by a spring 18. The lower part of the motor cylinder is connected by a pipe 19 to. a control member or pilot valve 20. comprising an outer casing 21,- a sleeve 22 connected by a stem and a pivot 23 to an, intermediate point of the follow-up lever v14. The pilot valve also includes'a pair of valve heads 24- and' 25 secured to-a stem 26 which in turn; is" connected to a speed, governor 27 driven from the turbine shaft. The arrangement 'so far described Iorms an, ordinary speed governing mechanism which operates as follows: During decrease in. load, causing an increase in speed, theflyweights otthe' governor move outward and effect downward movement of the pilot valve--heads.24and 25.' The pilot valve head 25 therebyuncovers a lower port-in the sleeve 22; and permits oil or 1 like actuating fluid being drained 'fromcunderneath the piston 17 of the hydraulic motor 16 7 through the pipe 19, the pilot valve, and a disof actuating fluid from. underneath piston 17 30 causes downward movement of the piston under the action of the spring 18 whereby the lever 14 {is turned in counter-clockwise direction about an intermediate point or pivot 29, resulting in I closing movement of the turbine control valve ll. vDuring counter-clockwise movement of the char e conduit 28'of.the latter. The draining lever 14 thesleeve 22' of the pilot valve is moved w downward, shutting off the connection between" the pipe 19 and tlie'drain pipe 28, or, from another viewpoint, resuming its "original relative, position withTesbettto the pilot .valve heads.

The mechanism so far described effects posi-' tioning' of the control valvefll in response to load changes but at the same-time it also eiiects' 5 a change-in speed with. changing load'of the s turbine. This change in speed will best .be' ap.-'

preciated by considering the fact .j-that during the above described operation the pilot valve heads- 24 and 25 have been -movedintoa lower -1 00 position," This lower position'corresponds to a difierentfpos itionof the flyweights of the speed governor. The inherent width of the regulation either ordinary speedgoverning mechanism is corrected or overcome bycorrecting means comprising a motor, in .the'present instance shown as ahydraulic moto'reo; and-a control mem-, ber i'or the motor shown as an ordinary pilot valve 31. The motor -includes a cylinder 32, a

piston33 therein having'a stem 34 piveted to 1. 0

29 of. thefollow-up lever 14. The piston 33 is I biased downward by a spring 35 and oil or like actuating fluid is admitted to and drainedfrom the lower chamber of the cylinder by a conduit 36 connecting the cylinder to the pilot'valve 31.

.--The latte r includes-a casing37 connected-ftp said,

pipe 36' and-having a supply conduit 38 and a drain conduit 39. The; connection ;of pipef36 with the pilot 'valve casing 37 is normally covered by a valve head 40'fastened to a stem 4-1'which' latter is pivoted to a fulcrumed lever-42. Thelever 42 has a left-hand end connected by an 1 adiustablelink 43to a lever 44 forming apart 5,

of the lever 14. I

The operation of the speed correcting mechanism is as follows: As pointed out above, the lever 14 is turned in counter-clockwise direction about anism in that'its connection with the iuicrumed lever 42 by the link 43 causes said lever 42 to be turned 'co'unter-clockwise about -,its fulcrum. This causes upward movement of the pilot valve stem 41Lwhereby the pilot valve head 40 uncovers its port, that is, the connection to pipe 36, andpermits' oil or like actuating fluid to be supplied from the inlet pipe 38- throughthe pilot valve and the pipe 36 to the cylinder 32: 01'] the-hydraulic motor 80. The piston 33 of the motor 30 then is moved upward against the biasing force of the spring .35, thereby turning the lever 14 about its connection with the stem 15 and moving the sleeve 22 of the main pilot valve upward. The upward movement of sleeve 22 permitsactuating fluid to be drained from'the j hydraulic motor 16 through the main pilot valve the Iulcrumed lever 42 'the pilot .valve head 40 of 20, causing Iurther downward movement of the piston/1'7, resulting in further closing movementof the turbine control valve 11, .efiecting a turther'decreasein speed until finally the'speed governor 27, the pilot valve heads 24 and 25.and

The'turning movement oi'the lever 14 during this operation causes through the link 43 and the correcting mean'sto resume its-original posi tion. As pointed out above, the link-43 is adjustable. In the. position shown, the correcting meansacts to maintain constant speed of theturbine, that is, zero regulation. I! the link 43-- is moved to thelett or to the right, positive or negative regulation may be obtained. a The correcting means for correcting thereg ulation of 'the ordinary mechanism has slow action which, as pointed out above, is undesir- "abl'e whenever sudden load changes on the turbine occur, especially when'load is. suddenly.

thrown of! the turbine. This drawback is overcome with my invention by'the provision of ing fluid to the correcting motor 30 in' response to a sudden decrease in'speed. In the present example I have shown a conduit 45 connected between the bottom of the cylinder 32 of the corrector' motor and the supply conduit 38 for the auxiliary pilot valve 31 including a valve 46 having its stem connected to one arm of a tulcrumed bell crank lever 4'7, having another arm 48 biased downward by a tension spring 49 r a wrest e "the above? mentioned intermediate point or pivot to normally maintain the lever valve 46 closed.- In proximity with the arm'48 is an adjustable link 50 having its upper end pivoted to the aforethe viulcrumed lever 42 is turned in counter-clock- 5 wise direction'about its Iulcrum during decreasing load on the turbine. II this decreasing load exceeds a certain magnitude the fulcrumed. lever 42 is turned sufliciently' in counter-clockwise direction to eflect engagement between the lower end .01 the link 50, that is, the screw 51, and the bell crank lever 4'1 whereby said bell crank lever is turned about its fulcrum to effect opening of thevalve 46. This permits actuating fluid to be directly supplied to the hydraulic motor 30 through the conduit 45,. effecting rapidupwardmovement of the piston 33.and'resulting in rapid closing movement of the turbine control valve 11 Thus, it'wili be readily seen that with the arrangement of the valve 46 and the means for actuating this valve, the action oithe correcting means is con,- siderably accelerated by taking away the control of the correcting motor 30' from the correcting pilot valve 31, thus eliminating the time element induced by the correcting pilot valve inclosing direction. This acceleration is important in that it prevents the speed irom rising beyond a certain value at. which the emergency governor wouldllil Having described the method of operation "0! my invention, together with the apparatus which I now considerto represent the best embodiment 115 1 thereof, I desire to have it understood that the {apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire tosecure by Letters Patentpf the United States is:

'1. The combinationof an elastic fluid'engine having a control valve for regulating the flow of elastic fluid to the engine, a speed governing .mechanism for regulating the control valve'in response to speed. changes, means for automati- 2. The combination of an elastic fluid engine having a control valve for regulating the admission of elastic fluid thereto, a speed governing mechanism for controlling the valve including a speed governor driven by the engine, a main hydraulic .motor for movin'g the control valve and a main pilot-valve connected to the speed governor for controlling the main hydraulic motor, means for correcting the regulation of the speed governing mechanism comprising an auxiliary hydraulic motor connected to the main pilot valve and an auxiliary pilot valve connected to the main motor for controlling the auxiliary motor, and means for accelerating the operation or the correcting means comprising a conduit including a valve for directly conducting actuating fluid to the correct- EDGAR D. DICKINSON. 150.

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