US2733611A - Turbine valve actuating gear - Google Patents

Description

Feb. 7, 1956 s. JAcoBs Erm.

TURBINE VALVE ACTUATING GEAR Filed U60. 26, 1951 Their' Attorney.

. l. I: l l 1 l .any

TURBINE VALVE ACTUATING GEAR Stephen Jacobs, Lunenburg, and Wayne E. Gleason,

Winchendon, Mass., assignors to General Electric Corn pany, a corporation of New York Application December 26, 1951, Serial No. 263,352 6 Claims. (Cl. 74110) through a horizontal lift bar with adjustable stop means v on the stems so that the discs will be picked up in a desired sequence 'as the lift bar rises. The lift bar is positioned by two or more vertical tension rods disposed through guide bushings in the valve chest cover plate. Various arrangements have previously been developed for positioning these lift rods by means of a hydraulic motor. Because of the very large forces which must be overcome by the motor, it has been found ditlicult to providela simple, compact, and light linkage means for transmitting these large forces without undesirable bending, which might result in inaccurate positioning of the turbine valves and deformation of the linkage parts unless they are made A extremely massive.

Accordingly the object of the present invention is to provide an improved linkage mechanism for transmitting force from the hydraulic actuating motor to the lift rods of turbine inlet valves of the type described.

AA further object is to provide an improved turbine valve actuating mechanism of the type described in which the hydraulic motor may be conveniently disposed at the side of the turbine valve chest so as to reduce the head-room required for the turbine, while resulting in very little increase inthe transverse dimensions thereof. This arrangement has the further important advantage of avoiding the chance that oil leaking from the hydraulic system will yfall on the hot valve chest and ignite.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawings, in which Fig. 1 is a' transverse assembly view, partly in section, of a steam turbine valve chest W'itha hydraulic valve actuating motor and connecting linkage incorporating the invention, Fig. 2 is atop view of the assembly, and Fig. 3 is an end View, partly in section. v

Generally,V the invention is practiced by providing ja ,Y United States Patent pair ofA syrnmetricallydisposed torsion tube members hav-` ing spaced portions connected to the valve lift rods and end portions connected to the hydraulic actuating motor,

the torsion members being supported by pivoted links on defining a valve chamber 2 in which are disposed a 'plu-f rality of valve` discs 3 adapted to seat on the respective' inlet ports 4. Each'disc has a stern 5 with an adjustable stop member, which may conveniently be in the form of a nut 6 threaded on the rod 5 and securedin desired,

adjusted position vby any suitable locking device. The stems 5 pass freely through the horizontal valve lift bar 7, which is in turn carried on two vertical lift rods 8, 9 slidably disposed in suitable bushings 10, 11 through the valve chest cover plate 12. This cover plate extends transversely to one side of the valve chest, the projecting por-iv invention, and are, therefore, not described in more detail.

`The type of valve arrangement shown will be familiar to those acquainted'withthe turbine art. Vertical movement of the lift bar 7 picks up the respectivestems 5 in a preselected sequence as ldetermined by adjustment'. `ofthe stops 6.

n It will be apparent that the lift rodsS and 9 are constrained to `move in `a vertical plane by the guide bushings 1t), 11.. Because of the comparatively' small diameter `of these rods 8, 9, which are intended, to be stressed principally in tension, it is important that there be no substantial transverse forces applied thereto by the valve actuating linkage.l

The hydraulic motor 13 mayr convenientlybe secured threaded fastenings 13e to the top` surface of frame portion It will be seen that the valve chest cover plate 12 and the transversely. extending portion 12a are of substantial thickness and wellable to `take any forces imposed` by the weight and action of the hydraulic motor.

Thus the cover plate 12 becomes the main frame mem` Actually, with` a force-trans--v mitting linkage in` accordance with the invention, only ber for the valve gear.

very small forces are imposed on the frame plate 12.

The force-transmitting linkage` to which this invention particularly relates comprises a'pair of torque tubes 14a, 14b disposed above Vthe frame plate "12 in paralle relation with the valve lift bar 7. An intermediate and one end portion of these torque tubes are connected to the valve lift rods 8, 9 respectively, while the other end portions H of the tubes are connected to the piston rod 13f of the hydraulic motor.

son of Figs. 12, and 3.

As perhaps appears most clearly in Fig. 3, each tubefl is penetratedrby a plurality of rod members identified These rod members may conveniently be 15a, 15b, etc. disposedy through drilled'holes in the torque tubes and links 18a, 18h, etc. ,lt will be apparent from Fig. -3 that each link 18 is pivotably received in a tting 19 suitably secured, as for instance, by threaded fastenings 20, to the frame plate 12.

The inner ends of the respective rods 15 are cutaway at opposite sides thereof to form a projecting at end por.- tion identified 21a, 2lb, etc. disposed at either side of, and Vpivotably connected to, the

respective end-fittings 22a,` 22h, and 22C, of the lift rods n i 9, 8, and hydraulicmotor'piston rod 131.'

As seen in Fig; 3, the pivots connecting supportlinks l The pivoted link means by which these.-` connections, are eiected will be apparent from a compa`ri` These at end portions are etc; The pivots connecting' the' upper ends of'sup'p'ort" links 18 with the outer ends` of the respective rods 15 are identified 24a, 24b, Y 24C, 24d, 24e, 241 The third set ofpivots connectin'g'theinner' end's ofV rods 15 with the valve lift'vrods and'pi'ston' ro'd a'reidentiied 25a', 255', 25e, respectively;

The operation of' the connecting' linkage' isV as'follows:

When the valve' disc's 3 are in'closed'p'osition, the lift barl Tis, of course, at its lowermost position and piston 13a is biasedto* its extreme lowermost position by spring 13b. When' hydraulic operating liquid` is supplied tothe motor 13, piston 13a moves upwardly against the"biasfofspring 13b s o" that.' the' piston' rod' fitting' 22e` pushes, upwardly onv the rod'end portionszl'e, 2 1'fv(Fig. 2' Since the load is represented'by'a downward force onthe lift rods v8, 9,

the upward thrust of'the hydraulic motor'loads. the tubesi 14a; 14b in'pure torsion. It'fwill be observed that; these,`

tubes'are of.comparatively'largey diameter so that they are well able to take these torsion forces. Itis also important to'note' that the symmetrical arrangement of the two parallel torque tubes insures that these forces will be" equally distributed so that there willbe no transverse forces imposed' by piston` rod 13f onthe'valve lift rods f Aswill be most readily'ap'parent from Fig. 3, upward motion'of the pivots 25a, 25h, 25e will be in a vertical plane byreason of the vertical guiding. effect of the bushings? 10,' 171 and the guide bushing 13gV of the hydraulic motor. It will also be apparent that the resulting. rotationalrmovement of the rods 15a, 15b, ete., about'ther respective pivots 24, will mean that the torque tubes 14a, 14b will bedisplaced slightly toward and away from each other; and this 'transverse shifting is permitted by the piv-V oted; support links'lS.

lt'will be apparent to those skilled in the mechanical arts; that the usev of two parallel symmetrically 'disposed torque tubes permits'the transmission of enormous 'forces from' the hydraulic motor to` the valve gear without the introductionV of any serious bending forces tending to deform the actuating linkage and without imposing any-V transverse forces on the valve-lift rods or piston rod,since theforce is transmitted as pure compression in the piston rod, pure tension in the valve lift rods, and pure torsion in the tubes '14. Y

It'will be seen that the invention yprovides an extremely compact andrugged'valve actuating linkage. which permits placing the' hydraulic motor closely adjacent the valve chest and at one side thereof, as contrasted withl prior art arrangements requiring the motor to. be disposed above or' below the valve' chest. Thesimplicity of the parts constituting'the' force-transmitting linkage, makes' the` mechanism substantially foolproof. All' parts are,

of course, readily accessible'for'inspection and lubrica-V tion;

It'will be'obviou's'that many changes and substitutions of equivalents may be made without departing from the spirit ofithe invention. For instance, While a hollow cylinder is the most efficient 'torque-transmitting member,- for afgvensize and'weght, it is possible-to make the members'14fz, 14b of other geometric shapes. Alsother var.-

rangements for pivotally supporting "the torque membersA could'be substituted for' the simple links'lS'. The arrangement is obviously applicable to turbines havingother types'of inlet valves and othertypes and arrangements of'hydraulic motor'for positioning .the'valvesfv It, is, of-

courseg'intended to'cov'e'r by the appended'claim's. all such modicationsas fall: within the tr'ue spirit and scope of the invention.

What IA claimas'new and "desire'to secure by Letters.

-Patent vrofith'e, United-*States is: A Y.

1 Infactatiug.linkage,fgrtransrnitting-force from anVV r.eciproeatingfnternberY to` actuatinetmetorwithf alinea. 1y at least two spaced., actuated'fmembers,linearlyerecips rocaille inthe samef--planeu asrtlie motor actuating-merit? V ber at opposite vsides of the free ends of said three reciprocable members, p'ivot means connecting said free ends' ofthe three reciprocable members to the respective adjacent side portions of the torque members, an'd at least two support link meanslconnected to each of said torque member, -each link means having one end portion pivotally secured to the frame' plate member'and the other'l end portion pivotally connected to the respective torque members at the sides thereof remote from said first mentioned pivot means, whereby linear motion of the actuating motor member effects rotational displacement of the torque members to cause the actuated members to move linearly relative to the support bushings. Y v

2. In actuating linkage for transmittingl force from motor" means having aY linearly reciprocable actuating member to'an actuatedmember disposed for reciprocating movement parallel to thek actuating member, thecombinationof a frame member disposed substantially in a'plane normal to the reciprocablemembers, bushing members secured relative to the frame member and adapted to constrain the reciprocable members to move in a' plane substantially normal to theframe member, a pair'ofseparate axially elongated torque members" disposed parallel to` the'fram'e at opposite sides of the respective' ends of the reciprocable members, *first pivot"means`connecting the ends of' thereciprocble members'to the respective adjacent"4 side portionsof theY torque members, and a pluralityof support link means connected to each torque member, each link means havin'g'one end portion pivotal- 1y secured to the frame member and theotherend por-v tionl 'pivtally connected to one of the torque members at' the side thereof remote from said'r'st pivot means, whereby linear movement of the actuating motor member effects rtational displacement of the torque members about'the supporting link means to cause the actuated member to move linearly in its'bushing.

3. Turbine valve actuating gear comprising aframe' plate'secured Vtea turbine inlet valve casing and having atleast two reciprocable valve positioning 'rod members adaptedtoslide in bushingmembers'disposed through' said" frame" plate wherebythe rod" members are' constrained'rto move linearly ina plane substantiallyv normal to thefr'ameplate, actuating motormeans securedtol the frav'me'plateV andhavinga reciprocabl'e actuating member disposed in the' same planeas and transversely spaced from the rod members, said actuating member having an endiportion aligned with the respective outerfends of ysaid rod Imembers,r apair of separate axially elongated torque'k members disposed parallel Vto the frame plate at opposite" sidesoffthe endsof said valverod members' and'vsaid' pivotally'cciinfected"toY the frame'pl'ate" and the votherl end pivotally connect'edfto' one of the 'torque members at'lthe side' thereof' remote' 'from said" first-mentionedt pivot means,` whereby linear 'motion of the actuating member eiiect's rotational displacement of the torque members to' cause the valve 'rod membersto move linearly in1 their bushings.

,4.v In: a mechanical actuator, the combinatn of 'amotor having a reciprocable actuating member, a recipro-` cableactuated'member, a frame withvguide means adapted to constrain said reciprocable membersto move in parallel: paths substantially normal'to the frame, a'pair of separateaxiallyelongated parallel torque members dis posed longitudinally of the frame at opposite sides ofthe reciprocable members, iirst pivot means connecting the reciprocable members to respective adjacent side portions of the torque members, and at least two longitudinally spaced support link means connected to each torque member, each of said link means having one end portion pivotally secured to the frame with the other end portion pivotally connected to a torque member at the side thereof remote from said iirst pivot means, whereby linear motion of the actuating member elects rotational displacement of the torque members about the support link means to cause the actuated member to move linearly relative to its guide means. t

5. Actuating mechanism in accordance with claim 4 in which the torque members' are tubes with longitudinally spaced parallel rod members projecting diametrically through and secured to the tubes, each rod having one projecting end portion pivoted to one of the reciprocable members and the other projecting end portion pivoted to one of the support link means.

6. In a mechanical actuator, the combination of motor means having a linearly reciprocable actuating member, an actuated member disposed for reciprocating movement parallel to the actuating member, a frame member disposed substantially in a plane normal to the reciprocable members, guide means secured relative to the frame member and adapted to constrain the reciprocable members to move in parallel paths, a pair of separate axially elongated parallel torque members disposed parallel to the frame member at opposite sides of the reciprocable members, pivot means connecting the respective reciprocable members to longitudinally spaced side portions of the torque members, and means rotatably supporting the torque members relative to the frame member, whereby linear movement of the actuating motor member effects rotational displacement of the torque members in opposite directions of rotation to cause the actuated member to move linearly relative to its guide means.

References Cited in the file of this patent UNITED STATES PATENTS Anderson Mar. 13, 1951

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