US2769432A - Hydraulic governor compensation system - Google Patents

Description

Nov. 6, 1956 A. e. MASSEY 2,769,432

HYDRAULIC GOVERNOR COMPENSATION SYSTEM Filed Sept. 27,- 1955 IN VEN TOR.

j ALBERT 6. MASSEY ATTORNEYS.

United States Patent HYDRAULIC GOVERNOR COMPENSATION SYSTEM Albert G. Massey, Watertown, N. Y., assignor, by mesne assignments, to Curtiss-Wright Corporation, New York, N. Y., a corporation of Delaware Application September 27, 1955, Serial No. 536,932

4 Claims. (Cl. 121-42) This invention relates to hydraulic governors for speed control and analogous uses.

The present invention relates generally to hydraulic governors of the type wherein the primary speed measuring element, a conventional flyball mechanism, connects directly with a pilot valve and, upon speed changes, moves the position of the latter, which in turn provides operating hydraulic fluid to an actuating piston and cylinder arrangement, the latter usually having connection with the control throttle of the prime mover, in cases where the hydraulic gov'ernor installation is serving to regulate the speed of such prime mover.

A practical hydraulic governor of the general type here under consideration must include compensating means in one form or another, such compensating means being provided to retard governor response and thereby avoid undue hunting during a correcting operation by the governor. The degree of compensation of governors of this general class varies according to requirements.

Where the compensating arrangement exerts a strong retarding influence the governor is naturally slower in its response to a speed change, that is to say, it is slower to produce an actual throttle change upon a speed change in the prime mover. In converse cases the compensation is termed weak, that is there is a lesser retarding influence eflected by the compensating arrangement and the governor, while quicker to respond to a given speed change, is more apt to produce hunting in the case of speed changes of considerable degree.

In the present invention a fluid pressure chamber is established which is compressed or expanded directly by movements of the pilot valve and by a compensating piston, both the pilot valve piston and the compensating piston communicating constantly with such fluid chamber. According to the present invention resilient pushpull means connect between the power piston and the compensating piston whereby movements of the former are not positively reproduced in the latter but are applied thereto in the form of resilient biasing forces.

Accordingly the compensating arrangement of the present invention comprises, in one piston and cylinder device, a basic compensating system and a combined accumulator and proportioning surge chamber arrangement. In the arrangement of the present invention the operating connection between the power piston and the resilient biasing means of the compensating piston is direct acting, the biasing means comprising a direct extension of the piston rod of the power piston, avoiding all mechanical linkages and other structural complications and then providing a simple and economical compensation and proportioning means.

The compensating system thus established comprises, under normal operating conditions, a closed fluid system save only for a leakage needle valve or similar adjustably reduced orifice which acts as a dashpot regulator directly upon the pilot valve in resistance to initial movement thereof.

Secondly, the needle valve acts as a bypass to propor- I Patented Nov. 6, 1956 tion the rate of time at which compensating fluid will act to close the pilot valve and thus proportions the degree of corrective movement of the power piston upon displacement of the pilot valve. Thirdly, the needle valve times the speed with which the pilot valve moves back to neutral in proportion to the speed of response of the engine so that the pilot valve will not move to open in the opposite direction under the pressure developed by the compensating piston.

In the general compensating arrangement of the present invention means are provided for acting in cooperation with the pilot valve fluid chamber and the compensating fluid chamber to provide a surge chamber both to serve as a pressure accumulator and to serve as a proportioning device to determine the degree of initial corrective movem'ent to be made by the power piston in response to pilot valve displacement.

Various other aspects of novelty are referred to and pointed out in detail in the following detailed specifica tion, taken in conjunction with the accompanying draw ing. It is to be understood that the principles of the present invention are not limited to the precise forms set forth by way of example, but only as defined in the appended claims.

In the drawing:

Fig. 1 is a general schematic view of one form of the hydraulic governor of the present invention; and

Fig. 2 is a similar but fragmentary view of a portion of another form of the governor of the present invention.

In the form of governor illustrated by way of example in Fig. 1 of the drawing the numeral 10 designates a shaft connectible with the engine or other device or system to be governed. The purpose and eifect of the governor system is to maintain a constant velocity of shaft 10 despite changes in load on the engine being governed or changes in other conditions which tend to vary the velocity of shaft 10 in other adaptations. Where the governor operates to maintain a constant velocity of shaft 10 despite differences in load on the apparatus being governed, for instance, the governor is said to be isochronous.

In the form of the invention now being described by way of example governing adjustment of the engine or other device or system being governed is accomplished by rotating or oscillating a shaft designated 11 in the drawing, and, in the case of an engine, shaft 11 may be connected with the throttle valve or other fuel control means as by means of an arm 12. In the case of engine governing operation the load on the engine is reflected in the angular setting of shaft 11.

The flyweight head and the hydraulic fluid system which cooperates therewith operates in a housing 14 and comprises a shaft or sleeve 15 which rotates in a suitable bore in housing 14 and, in the present instance, is fixed directly to shaft 10 and may comprise an extension thereof, the shaft 10 being driven by the engine being governed.

Shaft 15 is bored to receive a pilot valve 16 which has axially spaced generally cylindrical valve heads 17 and 18 and is formed at its upper end with an enlargement 19. A pair of flyweights 29 are pivoted as at 21 to yoke formations 22 formed upon a flyweight yoke collar 23 which is fixed to shaft 15 in any desired manner. Flyweights 20 include finger portions 25 which bear upon a pin or bar 26 fixed to enlargement 19 of pilot valve 16, so that outward pivotal movement of the flyweights 20 tends to move the pilot valve downwardly. An extension coil spring 30 is fixed at its lower end to enlargement 19 of pilot valve 16 and is supported at its upper end in a sleeve 31 which is carried by a casing 32.

Sleeve 31 is provided with internal means which support the upper end of extension coil spring 30 in such manner that the latter may be axially adjusted at its up- T T 3 per end to vary its resilient ing means of sleeve 31 is also provided with anti-friction means whereby the upper end of the spring may r tate freely withpilot valve 16 whilethe, sleeve 31 remains stationary. This spring supporting sleeve structure' isknown in the governor art and forms no part of the. novelty of the present invention and accordingly. need notbe further illustrated or'described herein.

From the foregoing it will be clear that any tendency '7 of centrifugal force to' move the flyweights outwardly,

upon increase in speed of theshafts 10 and 15, tends to move the pilot valve 16 downwardly in the bore of shaft 15. A decrease in speed evidenced-by a tendency ofthe flyweight s to move inwardly toward theshaft 15 results inraising of. the pilot valve under'the impetusof coil bias and the spring supportspring 30. The pilot valve 16 rotates jointly with shaft 15. but is free to move. axially therein as herein-indicated.

The necessary hydraulic pressure required for opera-.

tionlofthe governor is provided by apump indicated at shaft 15.

The housing 14 has a pair of passages 47 and 48 and shaft. 15 is provided with peripheral openings 49 and 50f which are normally' axially in register with. the valve heads 17 and 18 andalso register axially with the pas-. sages 47 and 48 of housing 14, as illustrated in Fig. l

I 'of the drawing- The exterior periphery of shaft 15 at openings 49 and 50 is grooved as at 51 and 52 so as to maintain con'tinuous communication between passages49 and 50' and passages 47 and 48; respectively, during rotation of shaft 15. s

' i Passages 47 and '48' cornmunicate, respectively, with the .upper andflower. sides of a cylindrical chamber 53 formed inhousing 14. A power or actuating piston 54 serves as a regulating member and is disposed in chamber 53 and has a piston rod 55 which connects pivotally with the outer end of an arm 56 fixed to shaft 11. In this way axial movement of piston54 in chamber 53 directly produces" rotative regulating movement of shaft 11 and thus the movements of piston 54 in chamber 53 directly determine and reflect the fuel setting of shaft 11, orany fluid pressure supply conduit 40, conduit 47 is connected with outlet passages 60 by reasonv of the lowering of valve head 17. This permits discharge of fluid from the space above piston 54 in chamber 53' through outlet passage 65. I l 7 V The casing 32 whichthouses the governor mechanism itself comprises a reservoir or sump for pump 35 and all of the-discharge outlets of the system discharge into the interior of casing 32 where they gravitate to the sump for' reuse. by the pump. In the form of governor-illustrated herein the level of oil'in casing 32 is maintainedsomea what as indicated at 70,so thatlall passageswhjch m ay V takein fl uid are submerged inthe hydraulic medium.

Pilot valve 16 is-further provided at its lower. endlwith a piston head 71- which-cooperates with the lower portion of the bore of shaft 15 to form a fluid pressure chamber 72.

Shaft 15 has one or-more radial passages 79 terminate x ing in a peripheral groove 80 ,which place the fluid pres sure chamber 72 in continuous fluid communication with a passage 85 inhousing 14. Passage. SS terminates in.

an adjustable restricted orifice by reason of a needle valve 90 which extends into passage 85 and is adjustedto more or less blockthe same by means of a threaded connection .91 in housing 14. It will be, noted that the outer end,

of passage 85 is continuously submerged in the hydraulic medium 70.

Housing 14 is formed with'a hollow cylindricalforma- 7 tion 95 which is disposed coaxially. with power'piston chamberr5,3 and is open at its lower end as ati96. Hollow cylindrical formation 95 forms a compensationpiston chamber 98 which is in free fluid communicationqat its upper end with passage 85 asfclearly shoWn in Fig.

1. A free floatingcompensating piston 99 is mounted in chamber 98 and,- in effect, forms the lower end ofthe. chamber 98 which is open to passage 85. f

A pair of pre compressed coil. springs'101 andi102' bear, respectively, against the top and bottom of com;

pensating piston 99. 'Lower' spring 102 seats against the bottom of'cylindrical formation 95 and the upper end of upper spring101y'bears against a spring seat or presother variable condition which shaft 11 may serve to adjust Shaft 15 is formed with radial outlet passages above upper valve head 17 and radial outlet passages 61' below lower "valve head 18. The upper outlet passages 50 are in continuous communication with the general interior of casing 32 in which the governor is enclosed by way of an internal groove. 64 in casing 14 and a passage lead- 7 ing outwardly therefrom. The lower outlet passage 61 likewise communicates with an internal annular groove' '67 formed in casing 14 and has free communication with V the general interior of casing 32 by way of an outlet pas-- sage 68.

It will be seen from the foregoin g'that in a general way accelerationof shaft 10'Will increase the centrifugal V i force on .flyweights 20 and urge. pilot valve 16 down ward.v The consequent lowering of valve head 18' connects. pressure supply conduit 40-with conduit, 48, thus .d'irectiug fluid pressure against the lower 'side of piston V 54.

This corrective movementj rotates shaft 11 in' a counterclockwise direction to decrease the fuel setting,

' in instances where an e ngineis being governed toaccompli shtheznecessary slowing of, shaft'10 to' its desired rssdl v 'Afthe same time hat conduit 43 is conriected'withj sure pad'104 which is formed at the lower, end of a 'rod 105 which'com'prises a downward extension; or tail rod on power piston 54. e V The operation of the foregoing and proportioning surge chamber structure will now be described, bearing in mind that the rudimentary governor operation involving merely the ,centrifugally' controlled pilot valve and the throttle controlling power piston is conventional and has been 'describedearlier herein. It will be noted that pilot piston chamber 72 and the space above compensating piston 99 in' cylinder are in free and continuouscomrnunication, and that the only ex:

ternal ingress or egress of fluidto the joint chamber thus formed is by way of the restricted orifice which is un- 5 der the control of needle valve 90.

The piston 99 and its associatedmechanismservea twofold function as coinpensating means and as a; proportioning surge chamber.

will; be; noted that piston 99, being heldrbetween the movements of pressure .pad 104, in turn, occur directly by and with movements of. the power piston 54. i

If springs 101 and 102 wereextremely stifi, so that. they operatedonly to directly proportion the movement of compe'nsatingpiston 99 to themovements of power piston 54, the compensating means thusproviddwould i:

a be particularly adapted to slow speedQengihes with heavy, flywheels and proportionately slow response. The: degree of governor response to a'changeinenginespeed can be governor compensating If we ignore other influencesf for the moment, for ease andclarity of description, it 7 V 60' 7 balanced springs 101 and 102 willrmove up and down in response to up and down movements of the spring; seat orpressu're pad member 104, in' direct. proportion; each movement of pressure pad 104 being accompanied. by a. similar movement, of piston 99 of one half the amount of the movement of pressure pad 104. The,

reduced to any desired speed of correction by adjustment of the needle valve 90.

If the load on the engine being governed is reduced, its speed tends to increase and the consequent outward urge of flyweights 20 moves pilot valve 16 downward. This movement is resisted by the fluid under piston head 71 in chamber 72, its only mode of egress being past the restricted orifice in passage 85 formed by needle valve 90. In addition to this fluid resistance, downward movement of the pilot valve connects pressure from conduit 30 to the under side of power piston 54, causing upward movement of power piston 54 and pressure pad 104. This decreases the compression on spring 101 and the consequent excess pressure of spring 102 applies a resilient upward urge on compensating piston 99, tending to produce fluid flow from compensating piston chamber 98 into passage 85.

Again, because of the restriction interposed by needle valve 90, this movement tends to force fluid into chamber 72 and thus moves the pilot valve upward until movement of power piston 54 stops. The needle valve thus acts as a restrictive by-pass, and, depending upon its adjustment, the power piston 54 will move a degree sufficient to return the pilot valve 16 to neutral position.

At this point in the operation movement of the power piston and pilot valve are stopped but the engine, while approaching its initial speed because of the amount of adjustment imparted to rock shaft 11 by movement of power piston 54, has not gone down to initial speed. During this period the pilot valve is pushing down on the compensating fluid in chamber 72 with a force corresponding to the amount that the engine is off speed, and this force causes leakage past the needle valve while the engine is coming back to speed, the speed of such leakage being sufficient to prevent the pilot valve from moving away from neutral in the opposite direction.

If the throttle adjustment effected by the power piston 54 in the foregoing manner proves insufficient, the pilot valve again moves downwardly to further adjust the power piston, such further adjustment being of lesser degree than the first because the engine has partially returned to proper speed and the relative unbalance of the flyweight force is correspondingly less.

Upon an increase in load on the engine, a reverse governor operation takes place. The pilot valve 16 rises and power piston 54 moves downwardly. This tends to enlarge both the chamber 72 beneath pilot valve 16 and the compensating piston chamber 98. Thus, flow of fluid in passage 85 is from outside of housing 14 into the compensating piston chamber 98, the outlet end of passage 73 being submerged in hydraulic medium as heretofore described. The operation is otherwise the same in theory as upon reduction in load on the engine.

It will be noted from a study of the foregoing that the restricted orifice controlled by needle valve 90 serves a threefold function. First, it acts as a dashpot to regulate the initial pilot valve movement upon a deviation in speed of the engine being governed. Second, it serves as a by-pass to regulate the time period which will elapse before compensating fluid from compensating piston chamber 98 will raise the pilot valve 16 to neutral position and thus proportions the degree of governing movement of the power piston. Third, it serves as a time delay means during the period when the pilot valve is in neutral and motionless while the engine is responding to the completed adjustment of the power piston 54, preventing the pilot valve from opening in the opposite direction.

The system of Fig. 1 has thus far been described without considering the yieldability or energy-storing potentials of the springs 101 and 102 and, as described, is complete and operative for certain general purposes and to meet certain sets of operating conditions and factors. However, under certain conditions of use, the foregoing hydraulic governor system, without the energy-storing capabilities of the springs 101 and 102, cannot be properly adjusted or proportioned to satisfactorily meet operating requirements.

The yieldable, energy-storing nature of the springs and the manner in which they modify the operation of compensating piston 99, constitute, in effect, refinements or additions to the general governor construction, arrangement and operation thus far described. These modifications in the operation of the foregoing basicgovernor arrangement extend the usefulness of the underlying systern to applications and fields of usefulness for which the governor system without the compensating piston springs would be inadequate.

Compensating piston 99 will normally assume a neutral mid position in cylindrical formation 95, the precompressed springs 101 and 102 being of like characteristics. The push-pull action of the balanced force of the springs 101 and 102 on piston 99 causes the chamber 98 above the piston in cylindrical formation to serve as an accumulator in either direction, positively or negatively, from the neutral position where the forces of springs 101 and 102 are in equilibrium.

This accumulator action is particularly well suited to modern high speed engines with quick response to throttle adjustment wherein there is less tendency for the governor to operate too fast and cause hunting. This accumulator action imparts greater flexibility of operation and the more yieldable nature of the forces imposed on the pilot valve by the compensating system gives the pilot valve more flexibility in producing control changes in the position of thepower piston.

The embodiment illustrated fragmentarily in Fig. 2 comprises merely a modied arrangement of the compensating piston and its biasing springs and the manner in which those elements are related to the power piston tail rod. All of the other structure of the hydraulic governor of Fig. 2 is the same as that shown and described in connection with Fig. l and need not be further illustrated and described.

In Fig. 2 a sleeve or skirt formation extends downwardly from housing 14 to form a hollow cylindrical extension coaxial with the power piston chamber 53. A free compensating piston 111 is mounted in this cylindrical extension and a tail rod 112 extends downwardly from power piston 54 and through compensating piston 111 in free axial sliding relation to the latter.

A pair of compression coil springs 114 and 115 bear respectively against the top and bottom of compensating piston 111, the upper end of upper spring 114 seating against a collar 117 fixed to tail rod 112 and the lower end of lower spring 115 seating against a collar or washer 118 which is removably held in place at the lower end of tail rod 112 by a nut 120.

The compression coil springs 114 and 115 are precompressed as in the preceding example and the functional operation of the embodiment of Fig. 2 is precisely the same as that previously described in connection with Fig. 1. The main distinction of the embodiment of Fig. 2 as compared with the embodiment of Fig. I reside in the fact that the piston 111 of Fig. 2 and the tail rod 112 serve as mutual guides to maintain coaxial alinement of these parts and the open construction of the bottom of cylindrical sleeve 110 permits ready removal of the compensating piston and its compression coil springs for replacement or repair.

The compensating piston elements 99 and 111 may comprise diaphragm or any equivalent expansible chamber members and, instead of the balanced compensation piston springs described above, a single normally neutral or unstressed compression-extension coil spring of the push-pull type may be used in conjunction with either of the compensating pistons or their equivalent expansible chamber members.

What is claimed is:

l. A hydraulic governor comprising a hydraulic pressure-regulator cylinder and 7 .a piston-'tmovablestherein,,a source of operating fluid pressuretheretor, a: pilot valve movable in opposite directions-to connecttsaidfluid pressuresourceito movelisaid' regulator pistonTin opposite directions, aofluid pressure chamber and ,a piston movable directly with said 7 pilot valve for compressing and expanding said-chamber upon movement of the-pilot valve iniopposite directions, a compensating cylinder coaxial V with said regulator cylinder and a piston therein movable V to compress and expand said compensating cylinder chamber, said two chambers being in continuous fluid com- 7 munication, an adjustable leakage orifice leading from the fluid system comprising said two chambers to a source of fluid under subst'antiallyfno pressure, normally balanced opposed springs acting against opposite sides of said com- U pensating piston for yieldably tending to retain the same in a. neutral position, a' connecting rod extending, from said.'regulator piston into said compensatingcylinde'r'and having jmeans: acting against one ofsaid springs tolvary the neutral: position of said compensating piston upon movement ofsaid regulator piston. i a

2. A hydraulic governor comprising a hydraulic pressure regulator cylinder and a piston movablettherein, a

V source of operating fluid pressuretherefor, a pilot valve movable intopposite directions to connect said fluid pres sure source toymove. said regulator piston in opposite directions, a fluid pressurechamber and a piston movable directly. with, said pilot valve for compressing and ex: panding'said chamber upon movement Of-thepilot valve in opposite directions, a compensating cylinder coaxial with said regulator cylinder and atpiston therein movable to compress and expand said compensating cylinder chamher, said two chambers being in continuous fluid communication, normally balanced opposed springs, acting against opposite sides of said compensating piston for yieldably'tending to retain thejsamein a neutral position,

' a connecting rod extending from said vreg'ulator piston tinto saidcompensating cylinder and'having means. acting against one of said springs to vary the neutral position of said compensating piston upon movement of said regular piston. i e

r 3; A hydraulic governor comprising a hydraulic pres- 7 sure regulator cylinder and atpiston movable therein, a

source of operating fluid pressure therefor, a pilot valve movable in opposite directions to connect said fluid pressure source to move said regulator piston in opposite directions, a'fiuid pressure chamber and a'piston movable directly with said pilot valveffortcompressing'and ex panding said chamber upon movement of the pilot valve inopposite directions, a compensating cylinder coaxial with-said regulator cylinder and a piston therein movable to compress and expand said compensating cylinder chama her, said two -chambers being in continuousfluid communication, an adjustableleakage orifice leading from the fluid system comprising said two 'chambers'to asource of fl id unde ub t a no P su o m lyaba anced opposed springs acting against opposite sides of said compensating piston for yieldably tending to retainthe same in a neutral position, a connecting rod extending from'said regulator piston into said compensating cylinder and hav: ing means acting against one of said springs to vary: the neutral position of said compensating piston upon move;

mentof said regulator piston, said connectingrod means acting on said one of said springs to yieldably compress said compensating cylinder chamber upon compressing movementof said pilot .valve piston and yieldably expand the same upon expanding movement ofthe pilot valve Alivdr i r r mPfi a ydr ul gp essure regulator cylinder'and a piston movablejtherein, a

sourceof operatingfiuid pressure therefor, a pilot valve movable intopp osite directions to' connectsaid fluid pres-- sure source to move said regulator piston in opposite directions, a fluid pressure chamber anda piston movable directly with said pilotvalve for compressing and'expanding said chamber upon movement of'the pilot valve'in' opposite directions, a compensating cylinder coaxial with yieldably tending to retain the same ina neutral position,

a connecting rod extending from said regulator piston' into said compensating cylindeoand'having means acting against one of said springs to vary theneutral positionof saidcompensating piston upon movement of said -regut-r lator piston, said connecting rod means acting on said one of said springs to yieldably compress said compenr sating cylinder chamber uponucompressing movement of said pilot valve piston and yieldably expand the same upon expanding movement of the pilot valve piston.

References Cited inthe file of this patent UNITED STATES PATENTS 2,312,464 7 Ziebolz Mar."2, 1943 2,484,557 Eckman Oct, 11,1949 2,623,503- Parker Dec. 30, 1952 Rodek Dec. 30, 1952

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