US2516723A - Self-compensating pilot means for hydraulic governors - Google Patents

Description

July 25, 1950 Filed Jan.

A.H.RODECK ETAL SELF-COMPENSATING PILOT MEANS FOR HYDRAULIC GOVERNORS 62 [III A V o 1 /02 405 27 Ls 44 l/V wax 7025 Arm/r; H. fiodech and Albert 6. H0559! Patented July 25, 1950 SELF-COMPENSATING PILOT MEANS FOR HYDRAULIC GOVERNORS Armin H. Rodeck and Albert G. Massey, Watertown, N. Y., assignors to Massey Machine Company, Watertcwn, N. Y.

Application January 2, 1947, Serial No. 719,682

3Claims. 1 This inventionrel'atesto governors for speed control and similar adaptations.

The underlying principles of governor control are adaptable to controlling and regulating various conditions and the principles of the is attained as nearly as possible'by a direct present invention are not limited to any particular field of governor adaptation. However, the widest present field of use of governors is probably in the control 'of the speed of internal combustion engines and as a convenient wayof setting forth the principles of the present inven- In conventional flyball governors, the centrifugal flyballs are direct acting and not only indicate speed but also serve directly as a source of mechanical energy to change engine fuel setting. In such governors a corrective fuel change requires a substantial speed change to overcome friction in the various parts. This results in a tendency to over-govern, whereupon the governor makes an adjustment by a series of over-shooting oscillations in the fuel setting change which gradually damp out at the conclusion of the governing adjustment. This undesirable phenomenon is knownas .hunting and various expedients and auxiliary mechanisms have been availed of in an endeavor to reduce hunting, and its attendant objections and undesirabilities. In some instances the hunting oscillations never damp out and hunting is continuous.

In view of the undesirabilities of direct acting centrifugal governors, particularly from the standpoint of sensitivity, a considerable field of development in'hydraulic governors has evolved. In the usual hydraulic governor, relatively small flyballs are used merely to indicate speed and to move a small pilot valve in a hydraulic system, the valve being arranged to release extraneous hydraulic fluid pressure energy for actually manipulating the fuel control system and other governor adjuncts. The speed change which produces a response in'hydraulic governor application can be very much less than in a direct acting centrifugal governor. However, special provision must still be made to eliminate or minimize hunting and conventional hydraulic governors employ complicated hydraulic and mechanical systems to effectcompensation, that being the term generally given to the function ofreducing hunting to a minimum, so that a new fuel setting due to governor adjustment movement from the old to the newsetting without objectionable oscillation.

The present invention has to do with the substantial elimination of the complicated auxiliary mechanism ordinarily employed in governors generally to effect compensation. The principles of the present invention'ar'e applicable both to mechanical centrifugal governors where the centrifugal force directly effects correction and to hydraulic governors wherein a hydraulic relay effects the ultimate correcting adjustment. In its broadest aspect the present invention involves a forced continuous phyiscal reciprocation or oscillation of the member that is immediately responsive to centrifugal action. Or, even more broadly, the present novel result, achieved by any suitable means to that end, is that adjusting element which is controlled by the governor moves to a new position of adjustment by a series of small steps.

This oscillation is not primarily dependent on the condition of the governor and may be a continuous oscillation of constant frequency occurring at all times while the governor is in operation. However, as a mere matter of practical expediency and since the oscillation serves no useful purpose when the governor is not effecting an adjustment, it is sufiicient if means be provided whereby the described oscillation is continuously produced during all times when the governor is making an adjustment incident'to a speed change of the prime mover or due to a voluntary change in the speed setting thereof.

In hydraulic overnors this oscillation is preferably applied directly to the pilot valve. When the pilot valve is oscillated continuously, even while no'speed change is occurring or being corrected for, the ports controlled by the pilot valve are so arranged as not to be affected by pilot valve oscillation when the engine is on speed. This can be accomplished simplyby providing an overlap as between the pilot valve and the ports equal to the amplitude of oscillation of the valve. However, as soon as a speed change occurs, the neutral oscillating center of the pilot valve is displaced and the pilot valve thus controls the ports by a series of short impulses. That isQthe ports are alternately opened and closed in rela tively rapid sequence'and the degree of opening becomes less and less as the speed approaches normal, because the center of oscillation of the pilot valve approaches its neutral position.

It has been found that this mode of controlling the pilot valve of a hydraulic governor .reduces over-shooting to practically zero without the necessity for any ancillary compensating mechanism.

Another particularly advantageous use of governors of the kind disclosed in this application,

is in controlling .the pitch of variable pitch aircraft propellers. In this field the-governor of the present invention is particularly desirable because of its simplicity and because its autocompensation operation gives greater stability than any other governor known to the art.

It is to be understood that the broad-principle outlined in the foregoing is not restricted in its application excepting as defined in the appended claims. However, by way of example, the present application sets forth a preferred embodiment of the invention. In the embodiment illustrated in the accompanying drawing and described in detail in the following description, means areprovided whereby .the pilot valve is oscillated only when :it .is displaced .from .its .normal neutral position. Inthis embodiment it is not necessary to provide an overlap between .the pilotvalve andthe ports controlled thereby excepting zfor'theusualoverlap of one thousandth of an inch or so provided merely for manufacturing tolerance.

:Figure l -of the drawing-is a. generalschematic view of one form of *the governorrof the present invention.

'Figure2 is a vcross-section :through the pilot valvehousing takenthrough one of :the pilot valve heads and the shaft ports :controlled thereby :of another form of the governor .of the present invention.

-In the drawing the numeral l 'designatesa shaft which is connectible with the engine =or other device-onsystemsto be: governed. The. purpose and effect of the governor system is tomaintain a constant velocity of the shaft "H3 despite changesinload'in the case ofan engine, .or -of other conditions tending to vary the velocity .of the shaft l9. .l-nathe alternative the governor serves to maintain a constant degree of .speed droop, thatis, a predetermined lessening of velocity with. increases in load.

The system-of the ,-present inventionvis readily adjusted to varying degrees of speed .droop, as occasion .may require, including --a.djustmen-t to zero speed-:droop, in which-case the velocity-is maintained constant regardless of .the load-within ;predetermined"maximum .load limits. .Speed droop-and the ability to accurately regulate-it are principally desirable when .multiple prime movers are operating in parallel against a common load-and it is desired that the load be uniformly distributed over. the-several prime movers.

Adjustment of the engine or other device or system :being governed .is accomplished .by-rotating-ashaft designated. H in thedrawingand in the case of: an en'gine the shaft l l I may -.be connected with the throttle valve or otherfuelmontro'l means, asby means ofanarm l2. Inaengine governoroperation the load on the engineds .reflected in-the angular setting of shaft] I.

The fly weight head and the hydrodynamic fluid system whichcooperates therewith isshown at'the right/in the drawing and; comprises a shaft orisleeve t3 .rotatable.in.-a support l4 andhaving .a resilient driving connection 15 withthe'shaft 18 which iswdriven by-thewengine \being governed. While the resilient: driving connection [5 is -:conventionally used'in thisart, itzmay'actually be omitted in .thegovernor arrangement ofthe presentinvention, which. is found .to eliminate .hunting under even the worst conditions encountered in operation. The shaft I3 is axially bored to receive a. pilot valve IB which has enlarged axiallyspaced valve heads 11 and! 8 and'is'formed "at its "upper end with an enlargement f9 forcooperating to support a plurality offly-weights it. The fly-weights 26 are carried by arms 2! which have a common pivot 22 at the outside of shaft iii. The arms 2| are pivotally engaged by links 23 which are also pivotally connected to the enlargeni'entiid of pilot valve it as at 2 5.

From the foregoing it will be clear that any tendency of centrifugal force to move the flyweights outwardly, upon increase in speed of the shafts "t6 and I3, tends to straighten the toggles which the arms 2| and the links 23 form, andthis results in lowering movement of the valve-i6 in the bore of the shaft I3. A decrease in speed, evidenced by a tendency of the flyweights to move inwardly toward the shaft J3, tends to collapse the toggles, and the links '23 accordingly raise the ,pilot valve It in the shaft 13. The .pilot valve flirotates with shaft It out is free to .move axially therein, subject to the forced oscillation which will be described hereinafter.

The necessary 'hydraulicpressure required for operation of the governor.is provided by a pump, indicated at '25, which may be .arranged to be driven from shaft ('0 by apair ofgears 2i and 28. The pump25 ispreferably of the reversible type wherein the output is uni-directional regardless of the direction of rotation of the,;pump drive means. The pump communicates with a conventional hydraulic pressure accumulator indicated at ZlLby means of a conduit 1'38, and the conduit '36 extends to the support .14 where it communicates with an annular passage 31 formed in support M and extending .aboutshaft It, the latter having a series -oflperipheral openings 32 whereby conduitfsl has continuous and uninterrupted communication with the space between valve heads l1 and H3.

The .pilot valve [5 is further "formed at its lower end with apiston'head35 which cooperates with the bore of shaft l3 to formia fluid pressure chamber 36. The chamberBG is provided .in a manner which willpresently appear, with a selectively variable degree of hydrodynamic fluid pressure, and suchpressure acts against piston head 35 to oppose the downward thrust which the centrifugal actionof the fly-weights?!) imparts tostem ilfi.

The housing Whas apairlof annular passages 3'! and 138 and the shaft 13 has a series of peripherally spaced openings in communication with each of the anniilarpassages. The openings in shaft 53 are designated 39 and 40, respectively, and are normally axially inregistry with the valve heads T1 andiS. The passagesSi .and 38 'have conduits 4-! and '42, respectively, which communicate with the upper and "lower side of a cylindrical chamber 43 formed in a housing element-M. A power or actuating piston '45 is disposed in chamber "'43 and has a piston rod 46 whichiconnects withan arm El secured to shaft Ill whereby movements of piston 45 in chamber "43 directly producerotative movement of .shaft H vand accordingly directly determine andreflectthe load setting of shaft H, or any other variable condition which shaft .Il may serve to adjust. 1

Ina general way, "it will be seen from'the'fore- -going that acceleration of shaft ID will, by increased centrifugal force on fly-weights 2B, lower .pilot valve 16 and, by lowering of valve head [8, connect conduit 31! with conduit '42. This directs "fluid pressure against the lower side of piston '45 and "accordingly rotates shaft H in a clockwise direction tadc'crease the fuel setting,

iii instances where anengine is being governed, to accomplish the necessary slowing'ofshaft tothe predetermined 'speed level. -As stated in the preamble hereto, the actuating piston may be used for regulating other governor applications. In the drawing the numeral 50 designates a tapered plug valve which extends across and controls passages 51 and 52 which connect the conduits and 42 with cylindrical chamber 43. The valve 50 is manually adjustable as by means of 'ahandle 53 and its position of adjustment determines the effective crosssectional areas of passages '5'! and 52- and this controlsthe rapidity with i which actuating piston 45 responds to changes in velocity of the input shaft and thus permits selective adjustment of the governor characteristic which is termed rapidity by those skilled in the art. Rapidity is a-term denoting the speed with which the actuating piston moves from one fuel setting to another. Instances where best regulation is attained by free and accurate adjustment of rapidity are found in the control of prime movers, notably two-cycle gas engines; g

It will be noted that'a further conduit 60 leads from accumulator 29 and this conduit supplies fluid pressure which serves as the source of ad justable hydrodynamic fluid pressure in chamber 36 beneath piston of'pilot valve 46. The hydrodynamic pressure in conduit 66 may be varied by reason ofthe fact that conduit 68 has an outlet'passageportion 6| whose degree-of outlet opening may be selectively varied by pivotal movement of an arm 62 which controlsthe d'egr'eelof opening. of an outlet valve 63 which may vary in-formbut-in the illustrated instance is a common commercial form of valve known in the art as .a cook or petcock. V Thenovel-mode of compensation which is here set forth by wayv of-example willnow be-described. The upper enlargement! 9 of pilotvalve [6' has fixed thereto-adiscfifi which'rotates with pilot valve l6 and fly-weights 20. In the forms shown, the disc 66 has a pairvof fixed preferably. .rounded .protuberances 6'! and 68 which normally pass just between'apair of relatively fixed fingers 69 and 10 during rotation of the fiy-weight mechanism and its related structure. .Fingers' 69 and 10 are supported by an adjusting screw H :which. is reversely threaded as at 12 and 13;

Screw. H is supported against axial movement inaywall portion 15 of the governor housingby means of a knurled knob 16 at one end of the screw and a collar 18 which may be fixed to screw 7| in any desired manner. Rotation of fingers 69 and '10 may be prevented in any convenient manner as by having their side edges abut the side wall (not shown) in the governor housing. Fingers 69 to 10 may be simultaneously adjusted by manipulation of knob 16 of screw H and'are normally spaced in such'manner that .the protuberances 6'! and 68 just clear the-fingers when the fiy-weight mechanism rotates with the engine .or other controlled device .on speed.

In normal operation and with the engine operating at a particular load and at a predetermined velocitysetting, the hydrodynamic fluid pressure inv chamber 36 below pilot valve I6 is such as to balance the centrifugal force acting upon =thefly-weights26 and tending to urge the pilot valve I6 downwardly; Accordingly, the pilot valve remains in neutral position where the valve 'heads II and l8 close"conduits 4| and 42, re-

spectively. I

" However. 'upon an increase in speed of the flydegree-tr constriction.

weighted-0', --th'ei'r: addedicentriiugal force cvercomes the-fluidpressure' beneath pilot valve .l 5, as determined by :th'e'setting of outlet valve .63, and the "pilot valve; I 5 tends :to move downwardly to connect fiuidpressure conduit 3t with conduit ii-through passages 3i,32, 46 and..38, thus mov-v ingz'actuating-pistoni iii upwardly in chamber 43. 'lhis rtendency is arrested by camming engagee inent or protuberances" 68 of disc be againstfinger 2TB whichforces pilot valve H5 back to neutral' positio'nonce .during ieach rotation of. the ny-t-weightamechanism;- The pilot valve is thus caused to oscillate between .=its dislocated position, as established by the preponderance of centrliugaliorce over hydrodynamic pressure in cnambertii, and;a':neutral position. 1 1 llviovelnent of the pilot valve lfi'back to neutra position in the second phase '01" each cycle or. reciprocation thereor checks-upward movement or actuating piston-45 so that movement tnereoi toEa new position, reflecting 'a new i'uel setting orsna'i't ll recluce'd'in' value, is approached by aco'ntinuous'series of short intermittent increments; 1115 results in the attainment or a new more. clockwise and therefore-reduced i'uelsetting-or shalt l'i :.without any perceptible or appreciable degree of over-shooting.

.Each time the pilot valve 16 lowered from neutral position to connect conduit .30 momentarily with conduit 42, the fluid expelled-from chamber-. lsabove.pistontb passes through conduitfl'land discharges within the shait l3 above valve head'l l. Such discharged fluid may emerge irom'rshar't. it through openings 86 which are formed iii-shaft 13 to accommodate links 23. The fluid so discharged, which is conventionally a lubricant, I lubricates the linkage and other moving parts therebeneath.

"It will be understood by those skilled in the art that the entire mechanism of the drawing may be housed in a suitable casing of any form whose bottom may be used-as a sumpfor pump '25, whereby all discharge-outlets of the system discharge openly into the-casing, where they gravitate to the sump for re-use by the pump. The sump is indicated schematically at 8| in the drawins... Y

A decrease in centrifugal force resulting irom a'decreasei'nspeed of shaft Hl'and fly-weights 20'results'in"'a' reverse manner to-open' the fuel control. In such case, intermittent raising of pilot valve "I6 intermittently connects conduits 42' with discharge passages 82 and 83 formed in theshaft 13 and the housing 14, respectively. For adjus'ting'thespeed at which the governor is setjpto regulate the prime mover, or to vary other desired operating constants inother gov ernor applications, the outlet valve 63 is manually-tadjustable'to control the size ofthfe orifice leading 'from chamber 3B beneath' pilot valve l filandfthereby' control the hydrodynamic p es,- sure urging the valve"l6upward1y"againstthe downward urge imparted thereto by the centrifugal "force of the fiy-weights 20. The valve arm .62 which pivot'ally controls valve 63 has a link 85' which connects with a lever 86, theplatter having-a second link 8! pivotally connected thereto. The link B'Iis connected to a manually' settable arm 88. "For the moment we may consider the'thi'rd pivot of lever 86', designated 90, as fixed, and it will beseen that'with pivot 96 fixed oscillation" of arm 88 oscillates valve 63 to change it's I -"As; thus can described governor system is sothrations; its sp'ieeatein constant. it: any

given imardless: of indentuin =usual operatingilimits. .lt isedesiredthowevelf, to selectively. adj ust the ,;-.governor system "so as to introduce, when desired, adjustable controlled speed droop; thatiit a-lpredetermined, percentage of reduction .in speedier. .each increase in load. To this .end .the .pivot .90 of.lever..86..is monnected to a .92 .whose ather end pivotally engages alever 93. The lever \93 .has .a dulcrumsupport 94 whichiistadjustablettowardendiaway iromithe pivotal oonnection with $2 and -.the other end iofnleuer .93 pivotally engages .oonnecting rod of actuating .piston .45.

.In operation, .the positionof thethmttleicontrol shaftil .directl-yuzeflects the-.prevailingiload. Accordingly, the .arm 41., .connecting. rod MB, and the iaotuatorlpiston A5, thy etheir ipositions, also directly. reflect .the .prevailin -load. eAsishown in ,the. drawing, ianaincrease in .load .will 'cause connecting rod 45 ztoimove'downwandly. with theiulcrum supportifliset asshown, and with manual. speedssetting armi88iiniaigiven position, the ,pivotal econnection .between .link iii-1 iandulever 8.6. will serve Jasia iful'crum star .the latter. and

downward movement iof =.connecting erod $6 mil} accordingly:moveilinkifliiiupward azilliproducethe efiect of slowingitheispeed settingmynpeningithe valve 53 .in proportion thesincreasein 10ad.as evidenced bin downward .movementof .conneoting rodlt .7

decrease in hydrodynamic spressure ..he- Death the pilot waive J15wausesdownwardrmovement .thereoiiand results in ,pilot valve J6 .resumingia .normalineutrahnosition at a lowerlload setting of actuating piston 45 and ;.sl1at LL. :By this means .the engine. speed ,reducedin proportion -to the increase inUloadiandisnccordingly a function varyin inverselyw-ith respect .to the load. While .the doregoingidescriptionof the speed .droop contro1. .ha-s, sior :clearness, been described sequentially, it is-t0 be understood that speed .droop adjustment-poems continuouslyiand automaticallyand mayioccur witheand during -.a governing and ycom pensating .cy'cle paused. {by .a change in .speed oj the iinpnt shaft i0.

,Movement or fulcrum :support :84, ;toward .the right as viewed in the drawing lengthens .the lever arm'.of theieonneciiingmm 14.6 :andeshortens the lever arm of a-the glink 1&2. rincreases ithe ratioiof the .conneetingirod .levler arm to 12118 link lever arm so .that ,themeroentageof :speedadroop is proportionately reduced. if ithe iulornm sup: .port M is amoved {so it-hat ,it is reoincident wvith the ,pivotal-conneotioniof dink 29.2 with lever 1&3,

ithen movement .of oonnecting :iroduifi iwill'rhave "While the primary -:consideration :in "governor operation is usual'ly annotate-speed controlesuch lcontrol is onlytdesi-red within :centain maximum .loadi'lirnits andiit-is desired thatzsnch maximum load -limits m-ay Joe rireely established :and andjusted. .It has previouslylheen indicatedathat the prevailing .load is directly indicated by Tthe werticaliposition-iof -theQoonneoti-ngirod -:Afi. :Aooord ingly a rojectiondidisiormedron-ithe connecting rod .46 .andliesdn .the path phone and ocf-ia :leyer '99 which is pivotally supportedaby ascrew Willi]. llhe other end .of lever :93 :connects with ;-a

a waive 403 which is disposed :inia ylinder .1 M.

gIIhe xeylinchar JM is-disposed in ;conduit .60- and a coinpression coil spring 4.0.5 normally .biases valve 4.134 til-o the illustrated position wherefluid flow through :conduit .60 by way (of .cylinder .104 is unimpeded. However, when the ;connecting rod :45 ,mones to a predetermined lower limit position the projection 38 engages the end of lerer 13-9 .and it :through dink Ml, raises valve Hi3 .so that when the predetermined load limit position is reached, svalve [Hi3 zhlocks conduit .68. Vertical adjustment ofthe positional pivotal s lllportir -g :screw 459.0 obviously varies the point at Whieh projection :98 engages .lever =99 and accordingly determines the loaddimit. Suchadjustinent isi-eiiec-tedby-changing :the axial position or screw 150B with respect to internally threaded fixed g-supports 1,01, -;which :is :accomplis-hedby manual rotation of lenolo Hi8.

While greatest eclearness of disclosure is .attainedibyitheischematic mode of representation employed in ithewdrawings, it will [be =understood by :those skilled inathe :art thatallvof '.the elements shown diagrammatically in-..the-.drawing :will he housed-1113a ;-suitableaunitaryecasing-iof any desired form and .oonfieuration, .as .ha been su ested previously herein. It will further he :,clear :to thosewskilled ,in the art that fall-pf the various adjustable timer-unis and valves will :havetsuitable connect-ions accessible from the outside of such easing and that suitable dials for indicating;;prevai1ing speed, :load limit-and speed drocp settings :will likewise :be .1provided. as is ic n- .ventionaldnthe art.

Various ,alternativemonstrudtions iandtmethods may-be employed v to achieve theegeneral: aim and purpose aoflthe present .invention,;-namely, elimination of the usual elahorateccompensating arrangements and the attainment "of what Elias previously eherein been called: auto-compensation. T-hesei alternatives may-comprise'merely alternative methods :for producing :oscillation of the :pilot valve or, as "will appear, may :comprise methods which iprod-uce :highfrequency .iinterinittentaapplication xof 'fluid :pressure energy :to change ii-he lfuel -'setting:2hy :CDlitillUOllSly :repeated intermittent iincrements without aoscillation of the pilot" valve.

'One alter-native method of "producing acoritin ous oscillation ":Of .the ;pilot 'val-ve :permits the (elimination-10f zthemechanioalirneans shown in Fig. .1 for:oscillatingtheipilotwalve. Thisalterna gtl'llfi :method srequires no mew "mechanical structure and itheref-ore JIBQIll-EES 'no :further illustration. :ikcccrding stoethiss-alternative,dhe particular proportions :setting zof "the :accumulator spring-and ithe accumulator valve are selected is :produoe 'FCOIifiIillOLlS automatic :oscilia'tion of the pi lotmalue at auparticular frequency. Since, according .to this :ealternative, pseiilation "of ine ;piiot vale-e is continuous even when no adjustsen-t '-:iS rheing made, it .is :necessary to :increase the ilength 1 0i @the ap'ilct-walve :he'ads i and to permit them :to overlap the merits 39 and flit py an-amountaequalito :the amplitude of.- os eilla'tion, sso :that :fluid :communication ftherethrough is established only when the pilot 'valve 'is shifted sfrom neutral. .:An overlap greater;tha1'i= the ampli- ;tude of cosciliatinn would "normally --be provided zinzpraotice to allow'ffor thefismallfoverlap usually gpr'esentifin anyinilotuvalve which is not oscillating.

:By seleeting'anzancumuiator spring of ;a partieula'r natural azibration frequency and by adjusting the accumulator setting in accordance {ill'whicluiniturniconneetsi im a myamq ulzog 75 therewith, ithe ipilot v-valve willaoscillatezat the same periodicity as the vibration frequency of the spring. Small pressure changes in chamber 36 produce changes in the effective area of the relief ports of the accumulator in its attempt to maintain constant pressure, and this produces the phenomenon of rapid pressure changes alternation between a maximum and minimum value at a frequency corresponding to the vibration frequency of the accumulator spring.

An alternative construction which entirely avoids the necessity for oscillating pilot valve I6 is achieved by merely omitting the annular passages 31 and 38 of housing I4. By this means the conduits II and 42, when pilot valve I6 is displaced from neutral, will communicate with openings 39 and 49 of shaft I3 only when such openings are actually passing the inlet to conduits 4! and 42 formed in housing I4 during rotation of shaft I3 in housing I4. This results in intermittent or pulsating application of pressure against piston 55 in chamber 53 during governor adjustment.

A more refined form of the alternative outlined in the foregoing paragraph is shown in Fig. 2 which is a cross-section through the pilot valve housing of this embodiment taken through one of the pilot valve heads and the shaft ports con trolled thereby.

In Fig. 2, the numeral I I4 designates a housing corresponding to housing I4 of Fig. 1 and an annular passage I31 in its inner periphery corresponds to annular passage 31 of Fig. 1. Conduit IlII likewise corresponds to conduit 4| of Fig. 1 and the numeral I I1 designates a pilot valve head corresponding to the pilot valve head I! of Fig. 1.

The numeral i I3 designates a shaft or sleeve corresponding to shaft I3 of Fig. 1 and is provided with a pair of radial passages 139 which are normally closed by the pilot valve head II? as in Fig. 1.

In the modification now being described, a pair of intermediate bushings I50 and I5I are disposed between shaft H3 and housing I M. Bushing I50 is fixed relative to bushing housing il and bushing I5! may be rotated to either of two positions of angular adjustment, one of them being illustrated in Fig. 2. Adjustable bushing I5I is provided with four equally spaced radial passages I53 and fixed bushing 150 is provided with two sets of radial passages. prises a pair of passages I56 which are diametrically opposed. The other set comprises four equally spaced passages I51.

When adjustable bushing I 5| is in the position illustrated in Fig. 2 it connects the two passages I55 of stationary bushing I56 with shaft II3 so that the ports 139 of the latter will communicate with annular passage I31 of housing l! twice during each rotation of shaft H3. In this position of adjustment the four passages I51 of stationary bushing I50 are blocked off by bushing I5I. If adjustable bushing I-5I be rotated 45 from the position illustrated, it will block off the two passages I55 of bushing I50 and establish communication with the four passages I51 thereof. This causes the passages I39 of shaft II3 to communicate with annular passage I31 four times during each rotation of shaft I I3 and thus doubles the frequency of the intermittent application of pressure in chamber 43 during governor adjustment.

What is claimed is:

1. A governor mechanism comprising a pressure chamber and a regulator movable therein One set comin response to differential pressure, a fluid passage communicating with the pressure chamber, a rotary member and a bearing support therefor, a pilot valve movable axially in said support in response to changes in speed in the rotary memher, an opening in said rotary member and means on said pilot valve normally blocking said opening, speed responsive means actuable by said rotary member for controlling axial movements of said pilot valve, said fluid passage leading to said rotary member in axial registry with said opening whereby, upon displacement of the pilot valve to expose said opening fluid pressure is transmitted to the pressure chamber in intermittent jets as said opening passes the fluid passage during rotation of the rotary member.

2. A governor mechanism comprising a pressure chamber and a regulator movable therein in response to diiferential pressure, a pair of fluid s passages communicating with the pressure chamher at opposite sides of said regulator, a rotary member and a bearing support therefor, a pilot Valve movable axially in said support in response to changes in speed in the rotary member, a pair of axially spaced openings in said rotary member and axially spaced valve means on said pilot valve normally blocking said openings, means for maintaining fluid pressure between said spaced valve means, speed responsive means actuable by said rotary member for controlling axial movements of said pilot valve, said pair of fluid passages leading to said rotary member in axial registry with said pair of openings whereby, upon displacement of the pilot valve to expose either of said openings to the fluid pressure in the space between the valve means differentfal pressure is applied to the regulator member in intermittent increments as said openings pass the fluid passages during rotation of the rotary member.

3. A governor mechanism for prime movers comprising a pressure operated actuating piston connectible with the prime mover for controlling the supply of an energizing medium thereto, a pilot valve for controlling pressure to opposite sides of said piston, speed responsive means for moving said pilot valve from neutral position upon a change in speed of the prime mover for moving the actuating piston to regulate the supply oi energizing medium to the prime mover, a relatively stationary abutment and means projecting from the pilot valve for intermittent engagement therewith upon rotation of the pilot valve, said abutment being outside the path of movement of the projection when the pilot valve is in neutral position but closely adjacent thereto, whereby when the pilot valve is moved from neutral position said projection is intermittently engaged by said abutment to return the pilot valve intermittently to neutral position against the action of the speed responsive means.

ARMIN H. RODECK. ALBERT G. MASSEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,151,522 Hodgkinson Aug. 24, 1915 1,511,425 Roucka Oct. 14, 1924 1,967,851 Wilson July 24, 1934 2,397,213 Smith Mar. 26, 1946

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