US1571977A - Fluid-pressure governor - Google Patents

Description

Patented Feb. 9, 1926, Y A,

Unirse *status HENRY R. TROTTER, SWARTHMORE,

isms?? PATENT oFFicE. f

PENNsYnvANIA, AssicNons 'ro WESTINGHOUSE nrncriaicaMANUFACTURING' COMPANY, A coRroaAirioN or PENNSYLVANIA,

rtninrnussunn GOVERNOR.

Application nii-a March-28,1924. se'rivaiNo. 702,498'. f

To 'all 'whom t may @carcerati Be it known that we, HENRY R'Tnor'rnn' nated iii which changes in position of the governingv mechanism shall'result only from chan es in speed ofv the prime mover governe. Y j -fy' Another objectV is to rovide av governor Y actuated by a variabley uid pressure motor whicli'shall operate unaffected by yvariations in pressure `at the inlet side ofthe fluid pressure developing means. f

lThese and other objects are accomplished by apparatus illustrated inthe accompany.- ingA drawingin which the single figure is a diagran'imatic view of ourimproved apparatus asapplied toga steam turbine.

"In-the operation of prime movers, especially steam -turbines, a very reliable vgovernor has beenpdcveloped in which the -governing mechanism is actuated by a fluid pressure motor, pressure for which is developedlby a centrifugal pump` driven' directlyvby the shaft of the prime mover, or in synchronism with it. Inasmuch as the pressure developed by the impeller of the pump varies directly as the square of the'speed the driving shaft, asthe speed of the primeinover in.-

creases, the pressure developed increases. By vpro\,1id'ing the fluid motor with a suitable leverage mechanism for utilizing the force l'exerted-by this variable pressure, veryv l dependable governing of the prime mover is" Y y I .1 Asa result of. this neutralization of forces,

accomplislied..l p Y As is well known, however, the total pressure of fluid delivered by av centrifugal pump is the sumof the suction head or inlet pressuieof the pump andthe pressure developed by its impeller. Withaconstant speedV of the the following is a speci' pump, there may be a variation in pressure delivered', due to variations'in the suction head or inlet pressure of the pump.VV

It has been found very difficult inthe design of this Vclass of governors to provide the pump with al uniform'suction head or inlet pressure. Hence, inl such apparatus, as the suction head varies, the pressure delivered by the pump -varies,resulting in variations inA position of the governing mechanism without variations in speed.

In Vthe application of Henry F. Schmidt,

Serial No. 688,292, filed'v January 24, 1924,

and assigned to Ve'stinghouse Electric and Manufacturing Company, there. is'illustrated and described apparatus for insuring at Vall times a positive supply of iiuid to the inlet of the circulating pump. In our governing device, weprefei' to employ apparatus similar to thatdescribed in the application aforesaid-for 'supplying the pump witha positiveinletpressure, although it will befapparentthat any kothersuitable means may be employed.

VWhile the apparatus disclosed in the application aforesaid insures a positive pressure at the inlet side of the pump, it cannot insure ja constant "or uniformk Ypressure at that point, Vdue to various ,operating conditions. This is equally .trueof any arrangement, with which we arefamiliar, employed` to accomplish the same object.

soV

To overcome theeifectofthisvariable inlet pressure on thek governing apparatus, we

'againstthe piston iny either direction isjneu.-

traliZed., and the" pressure effective for governing is solely that developed by theimrpellerjof the pump Vwhich varies as .the square of the speed'of. the drivingshaft.

any movement/of the governing mechanism in .operation will` bel caused `only by. changes in speed..

understanding of our invention, we show at Referringnow to the vdrawing* forja fuller 10 a fragment ot' a prime mover such as a steam turbine, and at 1l, a valve 'for supplying;- a motive iluid to the prime mover, said alve heini:y controlled bv our improved governing mechanism. At: l2 shown a tluid motor l'or actuating the governingl mechanism. This motor embodies a o vlinder lil having; a piston lei, and a piston rod lil. The piston rod i6 is operabljvv connected to a lever 1T tulerunied at 18 and Conner-ted at 1179 to a stem 21 Whieh aetuates the valve ll. The piston l-l is biased in one direction bv a spring` s2, which in tension between a stationary abutment 2B attached to the Cylinder 13 and an adjustable abutment 2- lattached to the lever l?. To var v the tension oil the spring; 2Q, regulating! means 2u are provided.

At 52T ive shou' u shalt olf the prime mover lt) whirh we emplojiY to drive the eeutrlfiulgal pump titl used to develop lu'essure `for the [luid .motor lil. The pump tl is oil the eouvrntional design and has :in ii'npeller 2li, an outletll and au inlet 82.

p ln the operation olf the pump 28, [luid is talien 'from a reservoir 323. lin order to insure a positive suction head or inlet pressure t'or the pump 3S, au ejector J'l--l is associated with the reservoir 3? and deli 'ers tluid at a relatively lov.' pressure into a cooler 35 'troni which it passes through a conduit 3o to the inlet side oit the pump Q8.

In operation the puiup 2S is driven by the sha'tt 27 oi the prime `mover and develops a pressure varying` with the speed oll the prime mover` which pressure plus the pressure at t-he inlet side of the pump is delivered through the outlet 8l and a conduit 23T to the cylinder 3 on one side oit the piston ,la-l. ln order to supply motive fluid to the ejector 3,4: a part of the fluid at a relatively high pressure is delivered through a eonduit 3S, leadingI `troni the pump 2S to said ejector. As previously pointed out, the ejeetor Elst delivers fluid under a relativelv7 low pressure to the inlet side 32 oi the pump 28.

lVhile the action oli the ejector ill insures a positive pressure at the inlet side ot the pump 28 at all times, this pressure will var v somewhat with the pressure oit the motive tiuid employed iu the operation oit the ejeetor and bv reason olf other operating` eonditions so that the inlet pressure will varr to some extent. In order to overeoine the elleet ott this variable pressure at the inlet side oi the pump, we provide a conduit 39 leading :lrointhe inlet side of the pump to the c vlinder lf3, on the opposite side of the piston 14; to that subjected to the fluid at a relativelY high pressure. lnasinueh as the pistou 1l is subjected on one side, to the tluid pressure developed by the iinpeller 29 et the pump 28 plus the pressure existent at the inlet side of the pninp at 43Q, and on the opposite side is subjected at all times through the conduit Si) to the pressure existent at the inlet side ot the puinp,` the pressure at the inlet side of the pump acting` on both sides of the piston lll is equalized and has no ef- ,iieet on the operation oi tl apparatus. lt follows, thereliore, that the eileetive governing 'torre is solely that resultant 'from varia tions in speed ot the iiupeller 25) of the pump 2S.

ln addition to supplyinga positive suetion head or inlet pressure for the pump and Alor imposing on one side ot the piston ll, the pressure e `istent at the inlet side of the pump, the ejertor 2li may also supply `fluid under pressure Jfor use in lubricating the prime mover. For this purpose, We sho u ronduit ll leading' troni the conduit Sti to a bearingl housing' 4192 oli' the prime mover lll. Alter the 'luid has been used as a lubricant in the bearings ot the primo mover it drains baul: to the reservoir l through a ronduit lil au shown.

From the 'ioregonugz it will be apparent that we have invented an improved grover nor actuated by tluid pressure iu ivhieh the nuivonients ot he govern mechanism are aetuated solel),- by @hanCS in speed oiE the tluid-pressnre developinel menus.

lllhile we have shown our invention in but one 'torni` it will be obvious to those skilled in the art that it is not so limited, but is susceptible oft various other changes and inodilieations, Without departing' :troni the spirit thereon and We desire, therefore, that only suchlimitations shall be` placer thereupon as are imposed by the prior art or as are speeilieally set 'forth in theoppended elainis.

that We claim is: p

l. In a fluid pressure governing` system, the combination of a fluid motor embodying ay pressure responsive element, a rotating` shaft, a eentrit'ugalpump driven bv the shaft for delivering;l tluid under pressure to 'the motorA` means :tor supplying' the punip with fluid under pressure, and means for delivering a eounterzuwtiup,r pressure oli fluid to the pressure responsive elementy 'tor olli-seteinig the ell'eets ot variations in supply7 pressure to the pump on the operation olf the motor. l A

In a governing mechanism actuated by a tluid motor mubodying a pressure respon-- sive element, the eoinbination ot a pump ter delivering litpiid at a relativelyvhigh pressure to the motor, means :tor supplyingthe pump with liquid at a relatively low pressure, and means tor deliveriiuia counter- :ieting pressure to the pressure responsive element to eliminate the etleot of variations in supply pressure on the pressure delivered to the motor.

3. In a governing mechanism, the Combination of a valve to be controlled, a fluid pieter for controlling the valve, inotor lio iso

embodying a cylinder and an operating piston Within the cylinder, said piston being ressure and means for delivering fluid to the other side of the operating piston at the same pressure as that supplied to the pump.

4. In a governing mechanism, the combination of a `valve to be controlled, a fluid motor for controlling the valve, said motor embodying a cylinder and an operating pist0n Within the cylinder, said piston being actuated by fluid pressure, a pump for delivering fluid at a' relatively high pressure to one side of the piston, and means for supplying the pump and the other side of the piston With fluid at a relatively' low pressure to offset variations in pressure supplied to the pump.

5. In a fluid pressure governing system the combination of a cylinder, a piston ivithin the cylinder, .a rotating shaft, a pump driven by the shaft for delivering fluid under pressure to the cylinder onrone side of the piston to actuate the latter, said pressure varying With theinlet pressure of the pump and with the speed of thel rotating shaft, and means for delivering fluid under pressure to the cylinder on the otherside of the piston, said pressure varying only with the being driven by the shaft, means for delivering fluid from the pump to the cylinder on one side of the piston, a fluid reservoir, an ejector associated With the reservoir forl supplying fluid to the pump intake andk to the cylinder on the otherside of the piston at a relatively low pressure to offset variations in pressure at the pump intake, and means for conveying the fluid at a relatively high pressure from the pump to the ejector as motive fluid therefor. A

7. In a governing mechanism for a prime mover, the combination of a valve to be oontrolled, a fluid motor for operating the valve, said motor embodying a cylinder having a piston actuated in one direction by fluid pressure and biased in the opposite direction by a spring, a centrifugalk pump driven by the prime moverfor delivering fluid under a relatively high pressure to the cylinder on one side ofthe piston, an ejector for developing a relatively low pressure of fluid, means for conveying, the .fluid under a relatively high pressure from the pump to the ejector for operating the latter, means Jfor conveying fluid from the ejector to the inlet of the pump to supply the latter with positive inlet pressure, and means for oonveyingfluid from the ejector te the opposite side of the piston imposing a load thereon in addition tothe spring and ofi-setting the 'effect of inlet pressure on thepressure delivered by the centrifugal pump.` 4 V In testimony whereof, We 'have hereunto subscribed our names this 26th day ofvlifarch i-rnuar'ia.y rriorrnn. HENRY r. SCHMIDT.

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