United States Patent: 3597101

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United States Patent	3,597,101
Kikuchi , et al.	August 3, 1971

AUTOMATIC FOLLOWUP CONTROLLER FOR A TURBINE

Abstract

An automatic followup controller for a back pressure type or air bleed back pressure type turbine which can be operated under either of control operation and pressure control operation, in which means is provided for adjusting the setting of speed governor means to follow the actual operating condition during a pressure control operation and for adjusting the setting of pressure governor means to follow the actual operational condition during a speed control operation, so that, when the operational condition is switched from the pressure control operation to the speed control operation, or vice versa, no abrupt change in load or speed on the turbine or a generator connected to the turbine and a smooth conversion of operation can be performed, and selector means is provided in each of passages which supply pressurized hydraulic oil from said pressure governor means and said speed governor means and said speed governor means to a servomotor means which controls a turbine control valve, said selector means being operative to selectively direct pressurized hydraulic oil from either one of said governor means to said servomotor means.

Inventors:	Kikuchi; Matuto (Hitachi-shi, JA), Nakatsuka; Tomoyuki (Hitachi-shi, JA)
Assignee:	Hitachi, Ltd. (Tokyo, JA)
Appl. No.:	04/840,223
Filed:	July 9, 1969

Foreign Application Priority Data


Jul 10, 1968 [JA]			43/47761/68

Current U.S. Class: 415/117 ; 415/17

Current International Class: F01D 17/00 (20060101); F01D 17/26 (20060101); F01b 025/00 ()

Field of Search: 415/17

References Cited [Referenced By]

U.S. Patent Documents


2977768	April 1961	Wagner et al.
3342195	September 1967	Wagner

Primary Examiner: Husar; C. J.

Claims

e claim . An uomic followup controller for a turbie comprising spee control piot valve means pressure control pilot valve means, each f said means being provide e for one sevomor means for ctuting valve means to control orking fluid into the tuine, said pressure control piot valve means being connected o pressure contr mechanism for operation i response to the ack pressure of he ubine, said speed control piot valve means bei connected o speee control mechanism for peratin in response o the otational speed of the ubie, nd switchingmeans provide in passage leadig from each of hepiot means to said sevomotor means for selectively directig a pressurie yrauic il ohlyfrom eiher ne f he pilot valve means o said sevomotor mes, heimprovemet comprising he provisin of he followup control piot valve means integral wihsai speed control pilot valve mems, whereby throufollowup piston means responsiveo said followup control pit valve means seti of piot usihig means for said speed control piotvalve means is maintained t a neural position itESPECT O SAID SPEED CONTROL PILOT NALVE means UING PRESSURE CONTROL PERATIN F HE UBIE with HE ITERVETION F A FOLLOWUP assembly MEANS. @. An utomatic followup controller for tubie comprisingspeed control pilot valve means nd pressure control pilot means, each f said means being provide ne forone servomotor mes for ctutig valve means to control workig fluid into he ubine, said pressure control pilot valve means being connected to pressure control mechanism for open in response o he ck pressure f the ubine, saidspeed control piot valve means being connected o speed control mechanism foroperatin in response to the rotational spee of the ubine, and switching means povie in passage leading from each of hepiot valve means to said servomor means for seectiey irecting pessurie hyrauic il ly fromeihe ne of the pilot valve means to said servomotor means heimprovementcmprisig theprovisi f followup control piot valve means intefral ih said pressure control pilot valve means, heeby hrouFOLLOWUP PISTON MEANS ESPNSIE O said FOLLOWUP CONTROL PIOT valve MEANS, SETING PSIIN F PILOT USING means FOR SAID PRESSURE CONTROL PILOT valve MEANS IS MITAIEEAT A NEUTRAL position IH RESPECT TO said PRESSURE CONTROL PIOT valve MEANS DUIG A SPEED CONTROL OPERATI F THE URBINE with HEINTERVENTION F A FOLLOWUP ASSEMBLYMENS. -. An utomatic followup controlle accordingly o claim , herein themovemet f said followup piston means is detece by sitch means, signal thus btaied being transmitted to sychronizig means so that he position f a movable fucrum of said

synchronii means is deemined accordingly o the uput f the ubine. 4. An auomatic followup controller ccding o claim 2, heein the movement f said followup piston is detected by switch means, a signal thus obtaine eig transmitte o sycronizig means so hatthe position of movable fulcum f said

syncroniig means is determied accordi to the output of a prime move 5. An utomtic followup controller according o claim 1, herein swichig means hic is provide in each f the passages f diecting he pressuried hyaulic il from said pressure control piot valve means and that from said speed control piot valve means o said servomotor means cmpises speed control swichig piot valve means and switching usig means whichre sliable i opposite directions with each the ude he action f hyrauic pressure and spring means, a pressurie yrauicoi FM mi il pump means being irected, hrouelectrical solenoi valve means responsie o a system isengageme signal to hydraulic cylinder means for si speed control switching pit alvemeans d

hat for said swiching bushig means 6. Anauomtic followup controller according o claim 2, wherein sitchig means hicis provide in each f the passges for irecting he pressurized ydrauic il from said pressure control pilot valve means and that from said speed control pilot valve means to said sevomotor means comprises pressure control switching pilot valve means and switching bushig mes which e sliable in opposite iections with eachothe ude the acting of hydraulic pessure and spring means, a pressurie ydrauic i from mai oi pump means being diecte, hrouhelectrical soleoi valve means responsie o a system engagemet signal to hyrauliccylinder means for said pressure control swichig poilot valve means and hat for

said switching ushig means. p,28 7. n auomatic followup controlle for a turbine comprising speed control pilot valve means and pressure control pilot valve mes, each f said means eingprovied nr for ne servomotor means for actuatig valve means to control working fluid into he tubie, said pressure control piot valve means being connected to a pressure control mechanism for operation in espnse to the back pressure f he uine , said speed control pilot valve means being connected o speed control mechanism for operation in response to he otatinal speed f he ubie,nd siching means provide in passage edig from each f the pilot valve means to said servomor means for selectively irecting a pessurie hydraulic oil onlyfromeithe ne of hepiot valve means to said servomotor means, he improvemet comprising the provision f spee control followup piot valve means intefral ih said speed control pilot valve means hereby hroughspeed control followup piston means responsive o said speed control followup pilot valve means, setting posiin f piot bushig means for said speed control pit valve means is maitaine t a neutral position with respect o said speed control pilot valve means during pressure control operation f the turbie with he interventin of a speed control followup ssemblymes, nd pressure control followup pilot valve mes intel with said pressure control piot valve means, heeby hrouh pressure control followup piston means responsive o said pressure control followup pilot valve means, a setti position f pilot ushig means fr said pressure control piot valve mes is maintaiedat neural positi wihrespec to said pressure control pilot valve means during spee control operation of the tubine with he ierventi of pressure control followup assembly mes.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a back pressure type turbine or an air bleed back pressure type turbine (hereinafter simply referred to as a back pressure type turbine), and more particularly to an automatic followup controller for enabling in such a type of turbine to convert the operation of a turbine smoothly from a pressure control operation in which a turbine back pressure is governed, to a speed control operation in which the rotational speed of the tubine is governed, or vice versa, without subjecting a turbine generator to a sudden change of load or speed.

In a back pressure type trubine, it is impossible to perform both a speed control whichutilizes speed governor means and a tubine exhaust pressure (back pressure) control which utilizes pressure governor means at the same time. If a turbine were so designed that the speed control and the back pressure control were simultaneously performed, thespeed governor means and the pressure governor means wouldinterfere with each other so that a stable turbine control would not be obtained For this reason, it has been a common practice to operate a turbine with wither one of the governor means inoperative. In a back pressure type turbine of this kind, when it is desired to perform a pressure control operation, a turbine grnerator is connected with another electrical system to maintain the rotational speed of the turbine substantiallyconstant, and the back pressure control isperformed by means of the pressure governor means with thespeed governor means iniperative. In a conventional arrangement, during a pressure control operation wherein a turbine generoator is operated in a parallel relation with an external electric power source, if the generator is disconnected from the external electric power source due to some possible reasons, an automatic switching means operates to make the pressure governor means inoperative and at the same time to cause the speed governor means start into operation. In this instance, it is usual that the opening of a control valve provided at the entrance of the turbine varies abruptly.

Tgis is due to the fact that, in a conventional turbine control means, the pressure governor means and the speed governor means are arranged in series in a pressurized hydraulic oil passage which is leading to a servomotor for controlling the control valve provided at the entrance of the turbine. Since the area of the oil passage in the speed governor means is larger than that of the pressure governor means during the pressure control operation, as soon as the operaon is switched from the pressure control operation to the g,3 speed control operation, the opening of said control valve abruptly increased so that it corresponds to the area of the oil passage in thespeed governor means. S imilarly, when the operation is switched from the speed control operation to the pressure control operation, the opening of the control valve is also abruptlychanged. The change in rotational speed of the turbine generator, which will thus occur during the switching of operation from the speedcontrol operation to the pressure control operation, will have a great influence on theoperations of various machines which are operated with an electric power supplyfrom the generator. Therefore, depending on the type of production, the quality ofproducts manufactured by suchmachines will possibly be adversely affected. (For example, in a yarn manufacturer, the denier number of yarns would varyk and in a paper manufacturer,the weight or thickness of papers would vary.) Thus, it has been desired to obtain governor means which is effective to prevent such a change in rotational speed of a turbine during switching of the operation For this purpose, various types of governor means has hithertofore been developed. However, these conventional means have the following disadvantages:

1. When the pressure governor means and the speed governor means are designed to have oil passages of substantially equal area, both of the means interfere with each other, so that the ranges of the setting value of the pressure governor means and the speed governor means, to which the operation of the turbine is intended to follow, are accordingly limited. 2. In a governor means in which the difference between the actual load during the pressure control operation and the setting value of the speed governor means by means of a microswitch in order to operate a governor motor so that the setting value of said speedgovernor means is adjusted in accordance with the actual load, die to the time required in operation of the governor motor and the inertia thereof, substantial time is required until the setting value is adjusted to an appropriate value after it is detected. If during this period of adjustment, said switchingof operation occurs, a sudden change of the opening of the control value cannot be avoided. SUMMARY OF THE INVENTION

An object of the present invention is to eliminate the aforementioned disadvantages of the conventional means and to provide an automatic followup control means which can adjust the setting of the speed governor means in accordance with the actual operational condition during the pressure control operation of a turbine or adjust the pressure governor means in accordance with the actual operational condition during thespeed control operation, whereby when the operation of the turbine is switched from thespeed control operation to the pressure control operation or vice versa, or continued operation of the turbine can be ensured without being sujected to a sudden change of the rotational speed or the load of the turbine.

Another object of the present invention is to provide a control means comprising an automatic switching means for switching the operation of the turbine to either one of the pressure control operation and the speed control operation, said switching means being dual-acting type so that it is effective even when a portion thereof is not working.

A further object of the present invention is to provide a turbine control means having means continuously movable in response to the output of a turbine to indicate the output.

Thecharacterized features of the present invention are in the fact (1) that the speed governor means can be quickly adjuated to a followup setting value directly by hydraulic means byt not by means of a governor motoor;(2) that a pressure control oil passage and a speed control oil passage and a speed control oil passage are arranged in parallel relation, either one of the oil passages is connected by means of a switching means to aervomotor means for controlling the turbine control, so that both of the signal levels for the pressure control and for the speed control can be completely equal; and (3) that said switching means is of a dual acting tupe so that even when a portion of the switching means is not working it canopeate without any inconvenience.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view diagrammatically showing a conventional turbine control means;

FIG. 2 is a diagrammatical view showing the arrangement in a conventional turbine control means;

FIG. 3 is a diagrammatical view showing an embodiment of the automatic followup conyroller for a turbine embodyingthe present invention;

FIGS. 4, 5 and 6 show thecharacter of a turbine speed controller;

FIG. 7 is a diagrammatic view of another embodiment of the automatic followup controller for a tubine embodyingthe present invention; and, p FIG. 8 is a systemblock diagram showinga further embodiment in which the automatic followup controller of the present invention is applied to both of pressure and speed control systems of a turbine.

DETAIOED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The outline of a conventional turbine control means will now be explained with reference to the drawings. Referring to Figure 1, the reference numeral 1 shows pressure governor means, a speed governor means 2, a load limiter 3 and a servomotor means 5a for actuating a control valve 6 which controls the flow of hydraulic fluid supplied to a turbine 61. As shown, the pressure governor means 1, the load limiter 2 and the speed governor means 3 are arranged in series in a oil passage leading to the servomotor means 5a. Since the oil passage of the speed governor means 3 is larger than that of the pressure governor means 1 during a pressure control operation of the urbine, when heoperation of he urbine is switched form he pressure control operation to a speed control operation, the opening f the control valve issuddenly increased so that it corresponds to the il passageof the speed governor means. Thus, the rotational speed of the turbine is increased to a certain alue.

FIG. 2 is a diagrammatical view which shows the aforementioned conventionagturbine control system in more detail. In this figure, during the pressure control operation, a pressurized hydraulic oil 11 feom a main pump (not shown in the drawing) is controlled by means f a pressure control pilot valve 12 connected to a pressure control mechanism 1, and directed through the load limiter 3 and a speed control pilot valve 21 to a hydraulic piston 5 to allow the tubine to operate withan otput corresponding to the speed control pilot valve 21 and a pilot ushing 22 (refer to numeral 22 in Figure 7) thereof are so arranged that they do not control the pressurized hydraulic oil. Thus, the speed control mechanism 2 does not control the pressurized oil. Fiure 4 shows the character of the speed governor means of the turbine, in which the abscissa expresses the output of a turbine generator and the ordinate expresses its rotationalspeed r frequency. In n operational condition in which he speed governor means is inoperative, its setting is determined to a value H which is higher han the rated rotational speed N, as shown by a straight line a in Figure 4. Supposing that the turbine output is P and the rotationalspeed is N and that the urbine is operated in a pressure control condition with the tubie generator arranged in a parallel relation withan external electric power source, if said generator is disconnected from he external electric power source nd the operation of the urbine is switched to the speed control condition, the control valve is further pened so that the rotational speed of the turbine is increased from Nto H. Thus, if the ubine oad P REMAINS CONSTANT BEFORE ND AFTER HE GENERATOR IS OSCONNECTED FROM HE EXTENAL POWER source THE SPEED GOVERNOR MEANS WILL CONTROL HE URBINE SO THAT ITS ROTATIONAL SPEED BECOMES H.

In case where it is possiblethat he variations in rotational speed of he turbine have adverse effects on the quality of products manufactured in factory utilizig he power f the urbine enerator, in order to limi the increase of he tubine rotational speed within an cceptablelimit .DELTA.f (refer to Figure 4), it is usual to operate he turbine iththespeed govenor means serving o a certain amount to limit he il passage uring he pressure control operating so that the setting f the speed governor measis displaced from the line a to ' and hat the difference 66 f between he rated rotational sped NF HE UBIE ND THE SET VALUE H' at the output f P.sub.1, so hatthe difference .DELTA.f between the setting spee and the rated rotational speed ill become larger han hat when the output is P. in order to maintain the difference .DELTA.f substantially cnstant, the following means have been conventionallyemployed.

When heoutput is changed from P o P.sub.1 and he hydrauic piston is owered in the direction shown y an rrow X, a return lever 23 for the speed governormens is rotated counterclockwise about a mvable fulcrm 73 comprising a portion of a synchronizing means 7, whereby a pilot bushing 22 of the pilot valve 21 for the speed overnor means is moved downwardly Thus, the relative position between the pilot bushing 22 and the pilot valve 21 is varied,so that 8 the restriction of the oil passage 22is slightlypened. By this movement, the setting of the speed governor means is varied from H' to H" (refer to Figure 4). At the same time, he followup lever 24 is rotated counterclockwise about a fulcrum located at an intermediate portion of the ever util a switch ctuator 29 carried at the right end of the ever closes a loweing contact 28L of a microswitch 28. Thus, he governor motor 1 is caused ro rotate to decrease the turbine rotational speed. Then, the movable fulcrum 73 of the synchronizing means 7 isupwardlydisplaced as shown by n row Y, so that the pilot bushing 22 is upwardly moved through he return ever 23. simutaneously with he upward movement of the movable fulcrum 73, the microswitch 28 is also moved upwardly, so that the contact of the switch 8 is ain pened when the fulcrum 73 is upwardly moved by a predetermined distance and the rotation of the overnor motor 71 is stopped. Thus, the movements of all of the parts are stoppe. In his manner, the overnor motor 71 is caused to rotate by such an amount that corresponds to he increase in the amount f offse .DELTA.f l f the setting of the speed overnor means so hat he icrease can be auomatically compensated to maintain he value .DELTA.f substantially constant.

The isadvantages of he conventional means have already been set forth, ut eh important onve will now be described i mre detail aking reference to Figure 2. (1) SINCE IN THIS KNOWN ARRANGEMENT THE pressure GOVERNOR MEANS - AND HE SPEED GOVERNOR MEANS @ ARE DISPOSED IN SEIES IN THE IL PASSAGE F THE PRESSURIZED OIL -- LEADING TO HE SEVOMOTOR MEANS %, IT IS IMPOSSIBLE O MAKE THE RESTRICTIN OF THE IL PASSAGE IN HE PRESSURE GOVERNOR MEANS - AND THAT IN THE SPEED GOVERNORMEANS @ DUE TO THE MUTUAL ITERFERENCE THEREBETWEEN. Therefore, the size of the il passage in he speed governor means 2 should necessarily be greater han hat in he pressure governor means 1. FORTHIS RESIN, THE VALUE F SHOWN IN Figure 4 cannot be sufficiently reduced and it is very ifficult to satisfy the requirements of users for making s smallas possible the abrupt change of the tubie rotational speed when he peratin of the tubie is switched from the pressure control condiin to the speed control condition. (2) When he mout of offset .DELTA.f is utomatically compensated, theoffset is deected by the switch 28 and the compesation is peformed by a governor motor 71. However, the accuracy of detectin by the microswitch is generallunstakle, nd even a small diffeece i the detecting function has a reat influence on the amount of offset, so that an accurate followup control cannot be expected. (3) When the ever mechanism 23 is operated y the rotating f the overnor motor 71, theinertil of the fovernormtor may possibly cause an overadjustment of the value .DELTA.f. (4) Since a sustantial time is consumed util the setting of the speed overnor means 2 is readjusted by he govenor motor 71 from he instant when he variation in tubine load is etected by the switch 28, if the operation of the tubine is switched from the pressure control condition to the speed control condition uring his transient peid, he rotational speed of the tubine il be aruptlychanged.

The present invention provies an automatic followup means in which he bove-mentioned disadvantages are eliminated. Figure 3 is a digrammatical view showig one embodiment of n utomatic followup controller for a tubine embldyingthe present invention. In his arrangement, a speed control pilot valve 21 is disposed above a speed control mechanism 2a, and a pilot valve bushi 22 whhich cooperates with the piot valve o control the hyrauic pressure for controlling he speed is connected wit LEVER @-. he ever 3 is connected at one ed wiha rod 5 nd t the other end with another rod 75, both f the rods 52 nd 75 are respectiely connected with a return ever 74 of a synchroniing means. Above he speed control pilot valve 21, the is provide a followup pilot valve 81 which is integrally manufactue with the piot valve 21, and a followup pilot valve bushing 82 which cooperates with he pilot valve 81 for producing a followup control hydraulic oil pressure is connected ih he return eve 74. The rod 52 has a lever 51 rotatably connected theeto at 52a. The lever 5 has one end connected with stem 5of a hyrauic piston 5 i a servomotor 5a for actuatig a control valve 6, and the other end connected with the lower end of a stem 83a f a followup piston 3.

A PAI OF MICROSWITCHES ARE DISPOSED ABOVE THE FOLLOWUP PISTON MEANS * AND ADAPTED TO E ACTUTE I RESPONSE TO THE VERTICAL MOVEMENT OF THE FOLLOWUP PISTON *- TO CAUSE THE GOVERNOR MOTOR &- TO ROTATE OR STOP.

utomatic switching mes 4 is employed for leading a pressurized hydrauic fluid either from he spee control pilot valve 21 and the pressure control pilot valve 12 through the load limiter 3 into the hydraulic piston 5, and diagrammatically shown in Fiure 3 i he form f a three-way valve. However, is ctual construction is dual-actuatig longitudinally slidably pilot valve type as shown i Figure 7 and the etai thereof will be described later. Further, in Figure 3, the connectins between the leves and the rods identified by hick dots are rotatable connections.

In Fiure 3, he parts are shown in positions i which he tuine is under a pressure control operation and the speed overnor means is performing the automatic followup conyol. he pressuized hyaulic oil 11P from a main hydraulic pump (not shown) IS ADJUSTED TO A predetermined PRESSURE BY THE PRESSURE CONTROL PILOT valve -@ WHICH IS CONNECTED TO HE PRESSURE CONTROL MECHANISM -A RESPONSIVE TO HE TURBIE BACK PRESSURE, AND DIRECTED THROUGH THE AUTOMATIC SWITCHING MEANS AND THE LOAD LIJITE - ITO HE HYAULIC PISTON % OF HE SERVOMOTOR %TO CONTROL THE OPENING OF THE CONTROL VALVE ".

On the there hand, the pressurie hyraulicoil 11S is directed, through he speed control piot valve 21 which is connected o the spee control

mechanism 2responsive to he speed of he urbine, into speed control pressure pipe 26 where i is blocke by he auomatic switching means 4. Thus, the il 11S does not act n he piston 5 and the turbie is operated uder a pressure control condition. In his condiion, as the back pressure of the turbie increses, the displacement of he pressure control mechanism 1a icreases and the amount of penig t the oil port 2of the pressure control pilot valve 12 ecreases resuting i n ecrese of the hydrauic pressure for pressure control. Due o his ecrese i the hydraulic pressure for pressure control, the yrauicpiston 5 is move ownwardly hereby the amou f opening of the control valve 6 is decresed and hus the tubine output is reduced.

In his condition as previusly poited u, if the speed overnor means as no followup function the relative movemet between the speed control pilot valve 21 and the pilot bushig 22 hereof il e such hat he setting of the speed overnor means is i effect increase.

ccoreing o ne embodiment f the present iuentin shown in Fiue 3, even he he hydraulic piston 5 is downwardly moved, the relatie positins of the speed control pilot valve 21 nd he pilot bushing 22 are not varied and kept in neutral position hus, the urbine can lways be controlled at he actual rotational speed. As the hyulic piston 5 is downwardly mved, the lever 51 is rotated couteclockwise about its riht end and mmentariy displaced to a position shown y a otted i.e. 51a.

The ever 51 has a rod 52 pivotally connected at 52a, and he rod 52 in un has a pai of levers 23 and 74 connected at the pposite ends heref. A ROD % IS further connected TO OTH OF THE LEVERS @- AND &$, SO HAT THE LEVERS %-, @- AND &$ AND HE RODS % AND % CONSTIUE A FOLLOWUP assembly The aforementione ownward movemet of the lever 51 causes said assembly to move downwardly bout a movable fulcrum 73 of the synchronizing means 7, and thus the lees 74 nd 23 are displace to positins shown y otted lines 74a l and 3i l respectiely.

When he eer 23 is displace o the position shown as 23i , the speed control piot valve bushig 22 which is connected thereto is also caused to move downwardly, whereby the bushing is downwardly, displace from the neutral position wirespect to the spee conyrol pilot valve 21. Thus, a condition which is equivalent to n incresed spee overnor setig can mometarily proeuced. On he of the hand, whethe lever 74 is downwardly displaced to the position shown t 74a, he ushing 82 for the followup control pilot valve 81, which is connected heeo, is also cause o move ownwardly, wihthe resut that he eural elationship between he bushing 2 and the followup pilot valve 81 is mmentariy roken. hus, the yrauic i pressure 11 T is diected through n upper oi port 82of the bushi 82 nd a passage 85 into the lower side of the followup piston 83 to cause he piston o move upwardly.

By this upward movement of he followup piston 83, the ever 51 is isplaced from he position 51a to the position 51bt the same time, he lever 74 is etune from he posiin 4to the iniial position shown y a solid ine The eer 23 is lso retune from he position 3i a to the initil position Whethe lever 74 is retuned o the iniil position he piot valve 81 nd its bushig 82 are retuned to heir neural relatiship. p Althouh the speed control pilot valve ushig 22 and he followup pilot valve bushig 82 re separately mde with each other he engths of the rods 75 snf 52 which are connected to the evers 74 and 23 are so detemie that the oil port control spl portions of the spee control pilot valve 21 and he followup control piot valve 81 and he oil ports in he usis 22 nd 82 exactly correspond ih each there so hat the bushigs 22 and 82 can operate as a uni. Theefore, hen he followup control pilot valve 81 and its bushig 82 are in the neutral elationship, thespeed control pilot valve 21 and its bushing 22 re also i he eural reationship. p s described above eve he he yrauic piston 5 for actuting the control valve is upwardly or downwardly move in response to the amount oftuie exhaus, the setting f the speedgovernor means is t changed. therefore eve when he ruine peratin is switched from he pressure control operating o the spee control peratin, the spee overnor means can mintai the speed f that momet and contiuously control he ubie takingthe place of the pressure governor means.

The above escried feure will now be described with efeence to Fiue 5 in connecting with opeational characteistics. When he turbine is perate uer a pressure control condiion with output P, he speed governor means is se long he i.e. a'0 with the amount of ffset 66 f is equal o ero. In his condition, when he tuine output is decrese to P.sub.1, the setting of the speed overnor means is varied from he lie a'0 o the i.e. a.sub.1, so hat the amu of offset .DELTA.f is maitaied o e e. Thus, he setting of the spee governor means is ouomicallydjuste i response to variation in ubie output

It should be oted hat the adjustment of he setti of he speed overnor means is obtaine not by any mnual actuation f he synchronizig means 7 shown in Figure 3 or the overnor motor 71, but y followup piston means responsie to the followup control pilot valve hrouh the aforementioned simple followup assembly.

In a conventional control means, he setig position of the sychroniing means 7 is indicated. In the control means accordingly to the preset invetin, in order to indicate the tuie utpu in he term f the setting f the sychronizig means 7, the microswiches 86 and 6L are connected to the governor motor 71. Thus, when he followup piston 3 is isplace from he preetemined eural position, the fact is detected by either one of the swiches 86H nd 86L, whereby the goveor motor 1 is cause to rotate so as to ctute the synchroniig means unit it is adjusted to position corresponding to the tubie output.

The present invention will now be described in connection wiha particular situatin in which he turbie output is decrese. As the utpu decreases, the hydraulic piston 5 is ownwardly moved d, as described previously, the followup piston 3 is upwardly mved. Thus, the switch actutor 87 causes the contqacts of the switch 86L so as to otate the overnor motor 1 in he iectin in which he speed setting f the speed overnor means is decrese. Wheeupon, he movable fucrum 73 provide in he synchroniig means is upwardly move so that he settinf f the sychroniig means 7 iupwardly move, so hat he setting of the synchronizig means 7 is indicate by suitablemeans such s neddle secure to the fucrum, nd at the same time, the lee 74 is upwardly moved o he position shown by 74b. p Thus, the ushing 82 for he followup control piot valve is shifte upwardly and he eural reatinship between the ushi 82 and the pilot valve 81 is broke, whereupon the pressuried hydraulic i 1 is diected through a ower port 82a of the ushig 82 and the il passage 84 into the upperside f the followup control piston 83 so s o exert a ownward pressure on he piston. p As a result, he ever 51 is reuned from the position 51to 51a, and he leer 4 is move from this position 74b o he position 74c. Simutaneously, the leve 23 is moved to the position 23c. Thus, all of the return movements are complee. he followup justment of the setting of they sychronizig means is aimed nly to establish the retain between the turbine output nd he indicatin f the setting of the sychroniing means. Theefore, its flowup rate d he accuacy of he fllowup fuctin oes to effect on he accuacy of the pressure governor means and the spee governor means.

accordingly to he preset invention, i is possible to dd o the speed govenor means an dvantageous function which could not be obtaied y a conventional means. The seting f the movable fucrum 73 of the synchroniig means 7 is determied to move along he i.e. a.sub.0, i.e. o a position i which he e rotational speed is btaie he he tubine oad is nouht, and the connecting by a switch 88, whereupon the spee overnormeans is llowe o utomatically fllow he perational condiion henthe tubine is operate under the pressure control condiion. In this condiin, if the tubie oad is completey shu own, the automatic swicig means 4 operates so hat he control of the ubine is performed by the spee ove means. Sice the mvable fucrum 73 of the synchronizig means 7 is located o position corresponding to the oload ated rotational speed, he position f he pilot ushi 22 for hespeed control pilot valve 21 is als located in such a position corresponding o he rated spee f he urbine when he oad of the tubie is ero. On the therhand, hesupply f he pressurize hydraulic oil 11 to he followup control pilot valve 82 nd hefollowup piston means 8 isinterrupted hen he uine is perate under he speed control condition, so hat the followup piston means 8 and the followup control pilot valve 82 becomes inoperatie.

Therefore, s described above, hethe turbie is peted with fill load under the pressure control operation, and he speedgovenor means is allowed o utomatically follow with he switch 88 ff, if the hole load is suddenly moved he tuine speed Aries s swn by cue b l i Figure 6 and ways ets the rated spee.

In Fiure 6, thecurve a represents he spee ariaion in a conventional turbie using a conventional speed overnor means observed when the oad n he ubie is shu own.

Figure 7 is a dirammatic view showig he arrangement of Figure 3 i more detail In his fiure, lock means 9 which cannot e seen in Figure 3 is shown, and he automatic switching means 4 shown in Figue 3 simply as a three-way valve is shown in greater detail

The auotmatic swiching means comprises a portion 4A for connecting either one of he pressure control hyrauic rluid or he speed control hydraulic fluid selectively to the servomotor 5a in accordance with the operational condition and another portion 4B for detecting the disconnection of the urbie generator from the electric system nd generating a power signal for swichinginto the speed control operation.

The portion 4A of the utomatic switching means icludes a switching ushig 41 which is downwardly iased by means of a spring 41S and upwardly move by a hydraulic pressure. Within the swiching bushing 41, here is isposed speed overnor switching pilot valve 42 which is upwardlbiased by means of a spring 44 and downwardly moved by a hydraulic pressure.

The pressurized hydraulic oil 11 from the main hydraulic pump (not shown) is directed hrouh solenoid valve 48A and a switching valve 47 ito a bushig actuating yraulic cylinder 41P in he portion 4A o cause the bushig 41 to move upwardly o its uppermost position. t the same time,theoil 11 is introduced into the pilot valve acutatig cylinder 42P to cause he pilot valve 42 to move downwardly o its lowermost position.

The pressure control hydraulic oil 13 is diected through il ports 43c, 41b and 43b, then through a conduit 32 and the load limiter 3 into the servomotor 5a to effect the pressure control operation.

The hydraulic pressure in the bushing actutig hydraulic cylinder 41P in he portion 4A is introduced into the followup control pilot valve 81 and served as a pressure course for he followup control.

The solenoid valves 48AAND $*Bare employed for actuating the switchingmeans i response to a signal epresenting a condition hatthe generator is disconnected from he eectrical system. the solenoid valve 48A IS NORMALLY OPEN AND IS ISEGAGED WHEN HE URBINE IS OPERATED UDER THE PRESSURE CONTROL condition WHILE HE SOLENOID VALVE $*B is normallclosed and is disegaged during pressure control operation.

Further, the solenoi valve 48A is of such ype that nce it is energized o closed he il passage nd hereafter he soleid energizing cicui is opeed by a switch (not shown), it is maitaied in he closed position so hat it is not utomatically pened. The soleoi valve 48 is again openee y a mnul actuation p In he arrangement as describe above, hena switching signal is generated during he pressure control operation for sitching into the speed control operation, the soleoid valve 48B IS ENERGIZE O E OPENED SO HAT THE SWITCHING valve $& IS UPWARDLY move through THE MECHANISM -)) WHICH IS CONNECTED O THE SOLENOID VALVE, HEEBY THE PRESSURIZED HYRAUICOIL WHICH HAS BEEN SUPPLIED TO THE portion $A and the followup piston means 83 is exhausted to drai pipe 47B. Thus, the ushig 41 is downwardly moved uder he ifluence of he spring 41S, nd he speed control yraulic pressure in he conduit 26 pass throuthe il ports 43a, 41a, 41b and 43b, and hen through he conduit 32 and he load imiter 3 into the ydrauliccylinder 5a so as to effect the speed control operation.

At the same ime, sice he hyrauicfluid whichas been supplied to the followup piston means 83 nd the lock means 9 is exhausted as described above, he lockig piston 92 downwardly moved under heinfluence of a spring which is disposed above he piston so as to close the oi passages fromhe followup control pilot valve 81 to the followup piston 83, whereby the followup function is cancelled.

Since he primarypurpose of the followup means is to make the setting of the speed overnor means to onform to he actual peratinal speed during he pressure control operating and it is meanigless to low he followup function valid after the operation is switched o the spee control condiin, he suppy f hecontrol ydrauic pressure is blocked d the locki means is put into peratin so that the followup function can e completey ceased.

he rrangemet in which he bushig 41 and the pilot valve 42 of theprtion 4 are both mvable s special meaning.

If it is only equie o seectivey introduced he pressure control hydrauic pressure in the conduit 13 and the spee control yraulic pressure in the conduit 6 into the sevomotor 5A, i woud be nly ecessary to make only one f hepiot valve 2 and the bushing 1 to e movable nd he the may be fixed (acully, a hyrauic selector f a conventional consruction is designed in such way). Howeve, if the switching valve cannotperform equired function competely ue o some possible reasons, he spee control yaulic pressure i he conduit 26 cannot e introduced into he sevomotor 5a, so that, even if he setting of thespeed ovenor means is perfectly djusted, he speed control ill become impossible fter he turbine eneator is disconnected from he systemeectricsouce esuting in an possile ccient.

In order o elimiate he possile angerous siution, according to he present invention the switchi ushing 41 and the piot valve 2 oth movable, ndin diti o hat, hey are mved in the irectins opposite to each there Furthemore,the yaulic pressure from he swichig valve is directed o act n both of the bushig 41 nd he pilot valve 42, so that upon completion of heir operation the switching from he pressure control operation to the speed control operatincan e perfectlyachieved. In rde hat the dual cting switching means is operate, it is ecessary hat the solenoid valve 48 isenegied o ctue he switching valve 47 through he mechanism 100 so hat the ydrauic fluid in heconduit 46 is exhauste, however hee is o ssurance that he swichig valve 7 is always perfectlctuted and there is a possibiity f incomplete operation.

In order o compesate for his icompleteness, hee is provide a soleoid valve 48A. The hyrauic pressure from the mai hyrauicpump is ormlly introduce hrouh he solenoi valve 48 ito he cylinder f the portion . hen signal for swichingito he speed control operation is eceied, the supply f he hydraulic pressure 1 ito the portion 4BISSTOPPED ND HE PRESSURE FROM HE SWITCHING valve $& IS EXHAUSTE. Thus, upon eceipt of hesignal for swichinginto thespeed control operation, the hyauic fluid in heconduit 46 is exhauste through oth f the solenoi valve 48 ND THE SWITCHI valve $&. present invention as hereofore been describe in connecting with he consructi and the function for utomically djusti the setting of hespeegovernor means duingthe pressure control operating If i is possible o utomatically djust he setting f he pressure overnor means in accordance with he operating condiin of hetubie uri he speed control peatin, theperatin f a back pressure type urbie oud eme moreconvenient.

hen tubine is starte, i is incresed in speed up o he rated rotatialspeed d hereafte connected into n electrical systemso hat an initil load is appliedthereon. Thentheoperation f the ubie is switched into the pressure control condition nd if anemegency condiion is encoutered duri he pressure control operation, it is agai sitcheio he spee control peratin. Throuhou hewhole operating he pressure ovenor means auomatically folws he actual urbie condition urig hespeed control peratin, while hespeed ovenor means utomatically follows the actual turbie condition uinepressure control peratin. According o this arrangement he ubine peratin can e switche t any time from one of he pessure hespee control operations to he the ihoutcretig any upt change in otational speed f he uine, so that he swichi f the operation can e performed in stable manne.

An emodime f the present invention hiccan satisfactoriy achieve the above fuctin is shown i Figue 8. InFiue 8, parts which correspnd o those arrangement shown i figure 3 are ientified y he same reference umerals and he principle herefis substantily identical to he previusly escried arrangement for peforming heautomatic followup operation f the speedgover means, sothatthe construction nd the function f his embodiment il be understood from the previus descriptins. herefore, his embodiment ill not e describe in eai bu ill e briefly explaie. p In Figure 8, the uine is shown in spee control condition. The pressurie hydraulic il 11S from he mai hyraulicpump is suppliedthrouh an oil passage constiuted by spee control piot valve 1S controlle by means of a spee control mechanism 2and piot ushig 2S thereof, nd hen througha switching means 4 nd a oad limie 3 into servomor means 5a for actuti control ave 6.

uring hespeed control peatin, pressure control followup assembly compisig ees 51P, 23P and 4P and ds 52P and 75P, pressure control followup pilot valve 81P andpessure control followup piston means 8P are in operation, whereby the seting f he pressure govenor means is contiuusy ejuste so hat it corresponds o the otationalspeed r the oad condition f he uine ui he speed control operation. In his

instance he speed controlfollowup assembly comprising evers 51S, 23S nd 74S and ods 5S and 75S does t perfm followup fuctin.

On heothe and, durithe pressure control operation the speed control followup assembly hespee control followup piot ave 81S andthespeed overnor piston mes 8S are in peratin, hereby heseti of hes eedgover means is continuusly juse so hat it correspnds to he otatinal spee and he oad condiins of theui e duingthe pressure control peatin. In his instance, hepressure control followup assemblydoesnot perform followup operation.

When it is desied, uing he spee control peratin, o djust the setiof thespeed ovenormeans to valvewhices t correspnd o 66 i f '0 bu slitly ierthan hat corresponding o ha actual operatinal condiin, theegths of the ods 52 and 75 may be adjusted ihrespectto echother. F his purpse,an djusti prtin 76 is provide t he connecting between heeer 4 nd the od 52.

heperatin f the utomatic selecti means for switcig he tubine peatin form the pressure control condition o hespee control condiion s already explained wihrespect o the embodiment shown i Figure 7. Theefore, he suppy f hepressurized hydrauic oi into he pressure control followup assembly i this operatinal condiion will ow be supplemearily explaine.

When signal is enerate iicatig hat he tubine generator is is connected from the eectric power system, he electric sooleid valve 48 is close d he eectric soenoi valve 48 is opened, so hat he hyrauicpressure in the conduit 46 is exhauste as previusly described

As the resu, the speed control hyraulicpressure 1S is supplied through he speed overnor means 2, the switchi means 4 nd he conduit 32 ito he servomotor means 5a, hereby the ubie peratin is swiched into hespee control condiin. At the same ime,he pessurize ydrauic oi which s pssed through he solenoid valve 48 is suppliedthrouh he conduit 46 ito he pressure control lock piston 92P andthepressure control followup piot valve 2P. Thus, the pressure control followup assembly comprising he eves 5P, 23P AND &$P and the rods 5P &%P is pu into operation p e present invention has heetofore bee described i cnnectin wie ack pressure type uine with respect to the sichi between he pressure control operation the spee control operati, oweveit should e ote that he invention is not imied to the appicatin o he back pressure type urbie bu is simiarly pplicable o n ir lee ack pressure ype turbine,nd it is,f couse, possile to make varius varitins and applications ihot eparting hespiri f the present invention.

As apparet from he above description he preset inventi provies, i he ck pressure type or air leed back pressure type urbine, means for justig he setting f spee governor means so at it always corresponds o he actual peatinal condiion through followup assembly whicis acute by a yraulic mechanismwhen he trubie is opeated under he control f pressure govenor means heeby when he uine geerator is disconnecte from n electric power system, the tubine operating cnswiche into he spee control condiin ihout causing y variation on therotatil spee and he load of he urbie eneator.

further according o he present invetin, means is provide for djusig the seti f he pressure overnor means hrouh fllowup assembly whicis actued by hyrauic mechanism, s that it always corresponds to the actu operatial condiion f he urbie he the urbine isoperate undethe control f thespee overnormeans,heeby when the truine geneator is put into parallel operation the electric power system, thepeati of hetubie can be swicheito the pressure crol condiin ithou causing y variation f eotatinal speed and he load of he ubie geeator. p Si further ccdig o he present invention he speed govenor means and he pressure governor means (have separate setting alue autmtic followup control mechanisms)WHICH RE PETE HYRAUICALLY, AND HENTHE TRUBIE IS OPERATED under HE CONTROL F EITHER ONE OF THE SPEED GOVER means AND HE PRESSURE GOVER MES (heeiafrer refered o as overnor mes f epresetig both f the mes, hethe of he governor means is auomaticallydjusted so that its setig value correspnds to he actual peratinal condiin, erey the control f heturbie can e swiche fromeithe ne of the overnor means to theothe without creti any arupt change of the rotatial speed and he d of he tuie enerator.

Further, ccordi to heprese iventin, here is provide a folowup control means hichcan ctute synchroniig means horuh followup piston means whichcooperate witSAID FOLLOWUP assembly ND A MICROSITCH, A movable FULCRUM OF said SYCHRONIING MEANS being ISPLACED IN ACCORDANCE WIHTHEUTPUT F HE TUBIE SOTHATTHEOUPUT can be INDICATED. P Stil further according o he preset invetin, hee isprovie a control mes vi uomtic swicing means f switching either one f he pessure control operation r hespeed control operati of the tuine,said swicing mes eig of a uacig upe nd even hen portion of he switching means is mufunctionig, theswichingoperation is to interupte.

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Current U.S. Class:	415/117 ; 415/17
Current International Class:	F01D 17/00 (20060101); F01D 17/26 (20060101); F01b 025/00 ()
Field of Search:	415/17