US1997456A - Elastic fluid turbine - Google Patents

Description

April 9, 1935.

E. D. DICKINSON El AL ELASTIC FLUID TURBINE Filed April 12, 1934 2 Sheets-Sheet l Q r rilillllillnill Inventor-s Edgar" D. DicKinson,

Arthur" D. Somes, FranKlin REricson; by

Their- Actor-ne April 9, 1935.

E. D. DICKINSON ET AL 3 1,997,456

ELASTIC FLUID TURBINE Fil ed April 12', 1954 I 2 Sheets-Sheet 2 Fig.5.

z 2/ l 22 20 I v I- 48 I a 46 w 43 g Inventor's: Edgar D. DicKinson, Arthur" D. Somes, Fr'anKlin R. Ericson;

Their Attorney I comprises a nozzle or nozzles and a single or.a

.mum in case a control valve is provided foreach v exploded views of a part of Fig. 1 under differe turbine Ifl'having a plurality of nozzles for direct- 'Patentecl Apr. 9, 1935 1,997,456, I a hmsrrorfmirn TURBINE Edgar- ,D. Dickinson, Beverly, Arthur D, 8011108,

I EastLynmand Franklin R. Ericson, Marblehead, Mass, assignors to General Electric Come pany, acorpor'a tion of New York Application April 12, 1934; Serial No.,=720,238 p a I 6 Claims. (01. ass-$9) The present invention relates to elastic fluid turbines comprising a bucket wheeland means for directing and controlling the 'flow or elastic fluid to said bucket wheel. This means usually chestt'I'I having an inlet I8 connected to a source of elastic fluid, notshown. The chest has *a'bottorn iii with a 'pluralityof ope ingsfor conducting elastic fluid from the chesttolthe groups of nozzles. Valves-.29, 21,22, 23,24, and 25 are provided for-controlling the flow of elasticfluid from the chestito' the groups of nozzles. The valves arecontrolled by a mechanism, in the plurality of throttle valves. The control of the flow of elastic fluid to the turbine by means, of a throttle valve or valves causesa loss of energy which reaches a maximum when the throttling is accomplishedby a single valve, This loss is considerably reduced by the provision of a plurality of valves for controlling the flow to a'plurality of groups of nozzles and the loss reaches'a miniresponse to speed or load changes of the turbine; The arrangement according, to ourlinvenconsecutively opened and closed While the other valves, 23, 24, and 25. are i opened. During, the opening of anyof the valves 23, 24, and 25, which nozzle. The last arrangement, however, is in "most cases prohibitive in view of the great manuiacturing cost. The'customary arrangement resorted to therefore comprises a plurality of groups 'of nozzles and a throttle valve for each group. .Each group may have the same number of nozzles or a different'number of, nozzles.

The object of our invention is to provide an improved construction and arrangement ofithe kind of turbines above specified wherebyiwith comparatively fewgroups of nozzles. and a separate valve for ,each group substantially the same control reflect is obtained as with an arrangement I inwhich the flow of elastic fluid to each nozzle is controlled by a special throttlevalve. V :For a consideration of what we believe .tobe 'noveland our, invention, attention is directed to the following description and the claimsappend- 'ed thereto in connection with the accompanying drawings which form a part of our specification.

In-the drawings, Fig. lis a perspective view partly broken away of an arrangement embodyingfour invention and Figs. 2 to 5 inclusive are 2 and 22, which may be termed primary valves, are consecutivelyclosed. The primary valves 29, *2I, and 22 are consecutively opened intermediate I the consecutivegopening of two sec ondary valves; Thus, the primary valves 26, 2|,

groups or individual nozzles II, I2, and I3, serve to subdivide/the large" groups "M IS, and I6, thereby effecting gradual, substantially uniform change in flow during valveopening travel and small loss in efiiciency bythrottling of elastic fluid. f p More specifically, the mechanism shown in drawing comprises a speed governor 26 driven from. ,the turbine shaft 2'! and-connected to the, right-hand end of a lever28 having a fulcrum 2-9. The left-hand end of lever 28 is connected toya fioating lever or follow-up lever 30 having an intermediate point connected to apilot valve or control member 3Iand itsleft-hand end v pivoted to a hydraulic, motor 32 controlled by the pilot valve. The latter comprises a cylinder 33 havm an inlet conduit 34 for receiving actuating fluid suchla s oil and a drain conduit 35 The connections. to these conduits are normally covered by valvelheads 36 and 31'respectivelysecured to a stem 38, which latter is connected to the intermediate pointof the floating lever 30. Aconduit ,39 isconnected between the pilot valve and, the hydraulic motor, 32. The latter includes a cylinder flfl having a, piston 4| movable there in and biased infa downward direction byda spring 42, The piston 4| is fastened to a stem 43 pivoted to the left-hand end of floating lever 39- and 1 having an upper; portion, connected to a rack rod 44. The lattenmeshes with ,a pinion 45 'operatingtconditions. V

The arrangement comprises an elastic fluid ing, the flow of elastic fluid in tea bucket wheel, not shown. In the present instance we have indicated six such groups of nozzles I I, I2, I3, I4, I5, and IS. The first three groups comprise only I one nozzle each, whereas the last three groups I4, I5, and I6, have four nozzleseach, that'is, a number greater by one than the total number of nozzles of the first three groups, or froma general viewpoint, if the number-of nozzles of each of the first or primarygroups is; n? and the number ofsuch groups is m we provide the secondor, secondary groups of nozzles with a num- I berfof, nozzles equal to (n m)+1. secured toacam shaft-46 n mas efl d s n u t dto h o r q h I T 1 a ran em n to ar esnri ad wellpresent instance indicatedas a speed governing mechanism, whereby the valves are moved in tion is such that the valves '28, 25, and 22 are may be, termed secondary valves, the, valves '20, I

and 22 for directing 'the,,flow to the primary known. During'operation, an increase in load" effecting a decrease in speed causes the fly balls of the governor to move inwardly, thereby efiecting upward movement of the right-hand end of the fulcrumed lever 28 and downward movement of thepilot valve stem 38. The lower valve head 33 thereby uncovers its port connection to conduit 3 1 and permits actuating fluidbeing sup-j plied through the pilot valve and the conduit 39 into the cylinder 40 of the hydraulic motor. The actuating fluid causes upward movement of the ment effects by a mechanism which will'be described hereinafter, opening of the valve means r and an increased flow of elastic fluid to the turbine. Upward movement of the stem 43 also causes upward movement of the left-hand end of the floating lever 3i), effecting upward movement of the pilot valve stem 38, which latter'thereby is restored to its original position in which the pilot valve heads 36 and 31 cover their ports. This is a usual follow-up arrangement.

[The six turbine control valves are moved by means including four cams ll, 58, 4 9, and 52 secured to the cam shaft 46. Movement of the bani 47 istransmitted to the primary valves 28, '2 l and 22 through a lever 5! having one end. provided with a roller 52'enga'ging the cam All and another end pivoted to a fixed rod 53. An intermediate point of the lever 5i is pivoted to a rod or stem fi l'which has a forked end 55 connected to'a bar 52. Eachlvalve 26, 2i, and 22 has a stem 57, 53, and 59 respectively, slidably pro- .iecting through. a bore in the bar. These stems are of different lengths and-their upper ends are provided with abutments 62 whereby the valves 22, 2i,'and 22 are consecutively removed from their seats as the bar 55 is moved upwards Similarly, movement of :thedcamsflil, 49, and is saidrod 53. An' intermediate point of the levers ti, 62, and 83 is connected'to stems 64, 55, and 66 respectively of the secondary valves 23, 24, and 25.

' The operation of the mechanism will be' more clearly understood from a consideration of Figs. 2 to 5 inclusive, showing anexploded view of the valves and the cams at different operating conditions of the turbine. "The position shown in Fig". 2 corresponds to that of Fig. 1 in which all valves are closed. Let us first consider the operajtion of the primary cam 41 and the primary van-c 211, 2!, and 22 during a complete revolu-- tion of the cam 41;"The cam has four valve opening surfaces 61', '65, 69, and Ill and four valve 7 closing surfaces H, 12, I3, and I4, assuming the cam. is turnedin one directiononly. To simplify the'arrangementthecam has been shown as a symmetrical star cam. If this cam is turned one-eighth of a revolution in clockwise direction,

a the camv opening surface 57 moves the roller 52 above, that is, after. one twenty-fourth of a revo V -luti'on, valve 20 would be opened, after two twenty-fourths of a revolution, valve 2| would "be? opened, andafter three tWenty-fourths or of the secondary valve 23.

one-eighth of a' revolution, valve 22 would be opened. The valves 2t, 2!, and. 22 are now in the position indicated in Fig. 3..-If the cam 41 is further turned another eighth of a complete.

revolution, the roller 52 travels along the cam closing surface ll, whereby the valves 22, 21, and Eli are consecutively closed in the order men-' tioned, reachingthe position indicated in Fig. 4. If the camel then is rotated another eighth'of a revolution, the valves are again opened and are again closed, reaching the position indicated in Fig. 5. reached after one-half of a revolution of the cam shaft. Whereas, I' have provided a single primary cam 4'l for the primary valves 20, 2!, and

after a further eighth of a revolution, the valves Thus Fig. 5 represents the position- 22, each of these valves may be controlled by a separate cam.

The relation between the operation of thepriinary valves and the primary cams and that of the '55, i5, and l! of the-secondary valve cams .48, 49, I andfifl respectively, the secondary valves remaining closed'(Fig. 3) During a further one-eighth l of a revolution of the cam shaft, the roller engaging the cam 28 travels along the cam opening 7 surface of said cam, thatis, the cam opening surface forces the .roller upward, efiecting opening During this period of time the primary valves have been closed, the

(Fig. 4)

another eighth .of a revolution, the primary valves are again consecutively opened, effecting steam supply through seven nozzles, and after a further eighth, that is,'after one half of a revolution; the primary valves are closed and' the secondary valve 24 is opened. Elastic fluid then is supplied :through eight nozzles to the turbine (Fig. 5).

Thus, whereas in .the position of Fig. 3 elastic fluid is supplied: through three nozzles only, in that of Fig. 4 elastic fluid is supplied through fournoz-L 'zles to the first bucket wheelof the turbine. After During this last period the roller for the secondary 'valve'23 engages the idling opening? surface 18 revolution, that is, after seven-eighths of a complete revolution, the primary valves are opened and elastic fluid is supplied through I all fifteen nozzles provided in the present arrangement. 7 From the above it will be readily understood that with our regulating arrangementjwhich in the present instance includes six valves and fifteen nozzles, the same effect is obtained as with'an arrangement in whichfifteen valves, that is, one valve for each nozzle, is provided. This results in a considerable reduction-of losses due to throttling and in a more uniform change of flow during the opening travel of the valves.

If the cam shaft 26 were turn'edmore than seven-eighths of a revolution, the rollers would .en-

gage camclosing surfaces 19', 82, and Si which would permit closing of all of the. valves during about one-eighth of a revolution of the cam shaft. In our preferredarrangement we provide means for limiting the angular movement of'the cams, in the present instance indicated as a stop 82 in the hydraulic cylinder 4! This prevents closing of the turbine valves by limiting the angular thereof and the operation of the difierentcams and the valves, in particular the relation between the operation of the primary camsand valves and that of the secondary cams and valves, is very similar to that described above with regard to in- -creasing load demand on the turbine.

Having described the method of operationof our invention, together with the apparatus which we now consider to represent the best embodiment thereof, we desire to have it understood that the apparatus shown'is only illustrative and that the invention may be carried out by other means.

What weclaim as new and desire to secure by Letters Patent of the United States, is:

1. In an elastic fluid turbine, a, plurality'of individual nozzles and groups of nozzles for di recting elastic fluid to a bucket wheel, means for controlling the flow of elastic fluid to the nozzles comprising primary valves for separately controlling the flow to several individualnozzles and at least one secondary valve for, simultaneously controlling the flow of fluid to a group of several nozzles, and means including cams for first consecutively'gradually opening theprimary valves, then gradually opening the secondary valve and simultaneously consecutively closing all of the primary valves, and finally gradually reopening the primary valves when the secondary valve is fully opened to obtain substantially the same control efiect asmay be obtained with a separate valve for each nozzle.

2 In an elastic fluid turbine, a plurality of individual nozzles and a plurality of groups of nozzles for directing fluid to a bucket wheel, a primary valve for controlling the flow of fluid to each of said individual nozzles, and a secondary valve for controlling the flow to each of said groups, means including cams for controlling the being opened and consecutive gradual opening of the primary valves after a secondary valve has been moved into full opening positionlfor.

obtaining a substantially uniform changeof flow during load increase on the turbine, f

3. In an elastic fluid turbine, a plurality of individual nozzles and a plurality of groupscomprising a number of nozzles greater by. one than the total of the individual nozzles, primary valve means for separately controlling the flow of fluid to each of said individual nozzles; secondary valve means -for separately controlling the flow of fluid to each of said groups, and meansfor operating both valve means to eifectduring load increase consecutive gradual opening of the secondary valvemeans and during the opening of each secondary valve means consecutive gradual closing of the primary valve means and intermediate the opening of two secondary valve means consecutive gradual opening of the primary'valve means to obtain a straight line flow characteristic of the turbine.

4., In an elastic fluid turbine, a plurality of individual nozzles and a plurality of groups comprising a number of nozzles greater by one than the total of the individual nozzles, primary valve,

means for separately controllingthe flow of fluid to each of said individual nozzles, secondary valve means for separately controlling the flow of fluid toeach of said groups, and a governing mechanism includinga cam shaft witha cam for operating, the primary valve means and a plurality of cams for operating the secondary valve means to effect during a certain load increase first openingof the primary valve means,

fully opened position consecutive opening of the primary ,valve means.

5. Inan elastic fluid turbine, a plurality of individual nozzles and groups of nozzles for diarate groups of a number of nozzles greater by,

one than the total of individual nozzles, a primary valve for-each of the first mentioned open? ings, a secondary valve for each of the larger openingsla speed governing mechanism including a speed governor driven by the turbine and a cam shaft operated in response to speed changes, cam means on the shaft for consecutively gradually opening the secondary valves during speed drop, and other cam means on the shaft for consecutively gradually closing the primary valve means duringthe opening of each secondary valve means, said last named cam means effecting consecutive gradual opening of the primary valve means prior to the opening of "each secondary valve means to obtain a straight line flow characteristic of the turbine.

6; In an elastic fluid turbine, a plurality of individual nozzles and a plurality of groups comthen opening of a secondary valve means and simultaneouslyjclosing of the primary valve means, and with said secondary valve means in 20.

prising a number of nozzles'greater by one than the total of the individual nozzles, primary valve means for separately controlling the flow of fluid to each of said individual nozzles, secondary valve means for separatelyfcontrolling the flow of fluid to each of said groups, and means for operating 1 both valve means to effect during load increase consecutive gradual, opening of the secondary valve means and during the opening of each secondary valve means'consecutive gradual closing of the primary valve means and intermediate the opening of two secondary valve means consecutive gradual opening of the primary valve means to obtain a straight line flow characteristic of the turbine, the meansfor operating the primary valve means including a cam having a plurality of cam opening and closing surfaces for causing a plurality ofv consecutive opening and. closing movements of the primaryvalve means during the consecutive opening of the secondary valve means.

, EDGAR D, DICKINSON.

ARTHUR D. SOMES.

FRANKLIN a. ERIcsou.

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