US2255439A - Governing apparatus - Google Patents

Description

Sept. 9, 1941. F. SCHMIDT 2,255,439

' GOVERNING APPARATUS Filed Oct. 10, 1940 3 Sheets-Sheet 1 INVENTOR WITNESSES:

HENR F -S-cHMmT. $6 4410 2' BY I h. R1 43,

ATTORNEY S pt. 9, 1941.

H. 'F SCHMIDT GOVERNING APPARATUS Filed Oct 10, 1940 s Sheets-Sheet 2 In In mama m M. o H M T C E v (M W fl 0 NF v m. a M 7 0- N J E n m Milli 0o mm 00 5 B E A Q 2 l. .8 0 A k k or w 7/ J ,Q, I' L hI 1 ,7 w fit 41 m amm o z y 4 7 2& A a m m w x A v mm m u mm 43 am .8 m 3 5 x m 3 M m .m

p 1941- H. F. SCHMIDT 3 GOVERNING APPARATUS Filed Oct. 10, 1940 3 Sheets-Sheet 3 Wli'NESSES: I I I INVENTOR ENRY E SCHMIDT v BY BM/5, g

ATTORNEY ingproduced thereby. In accordance with the Patented Sept. 9', 1941 Henry F. Schmidt, 'Lansdowne, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa.,-

Pennsylvania a corporation of Application October 10, 1940, Serial No. 360,549

. 18 Claims.

This invention relates to hydraulic governing mechanism for controlling the admission of motive fluid to prime movers and. it has for an Ob j'ect to provide apparatus of this character wherein the regulating or controlling pressure, in ad- I dition to controlling the position of the servomotor pilot valve, also serves to secure operation of the operating piston without the latter operation introducing fluctuations in the impeller pressure suflicient to impair the speed responsive efiect of the latter.

Heretofore, impellers developing liquid pressure and varying substantially as the square of the prime mover speed have been used to provide a controlling or regulating pressure for the servomotor operating the motive fluid admission valve.

f Ordinarily such controlling or regulating pressure is used to control the position of the servomotor pilot valve and the operating piston is moved by a separate source of motive fluid, movement of the operating .piston by liquid under' pressure developed by theimpeller being objectionable on account of. pressure fluctuations bepresent invention, movement of the operating Fig. 3 shows a third embodiment similar in many respects to that of Fig. 2; and,

Fig. 4 shows a fourth embodiment.

Referring to Fig. 1, there is shown a centrifugal impel1er,'at l0, driven from the prime mover-or turbine, at H, and furnishing controlling and motivating liquid for the servo-motor, at I2, which operates the admission valve l3. An important feature of the present invention is to provide for operation of the s'er vo motor by motive liquid supplied by the impeller without impairing the emcacy of the impeller pressure to exert a pulsation-free speed-responsive controlling effect on the servo-motor.

The impeller, at II], is of the type commonly used for governing purposes and it comprises a runner l4 and a casing 15.

v The casing provides a pressure'space l6 bounding the runnerand a suction space ll atone end'of the latter, the easing having an eye I81 axially aligned 'with the runner and opening into the suction space.

A suction conduit I9 provides for passage of liquid from the reservoir 20 through the eye to piston is secured by the application of fluid pressure derived from the impeller without introducbeing effected by the use of aconstant- -flow valve in the line supplying liquid from the impeller to the operating piston, the operating piston and its cylinder incorporating an accumulatorproviding, at least, for admission valve' closing movements which do not depend upon therate at which liquid is supplied to the operating cylinder.

A further object'of the invention is to provide ing such fluctuations or pulsations, this result servo-motor apparatus of the above character wherein the fluid draining therefrom is supplied to the impeller so as to improve the suction. lift of the latter.

A further object of the invention is to pro- .vide apparatus of the above character wherein the liquid used is lubricating oil and drainage from the operating cylinder is provided at a sumcient pressure for bearing lubrication.

These and other objects are effected by the invention as will be apparent from the following description and claims taken in connection with this application, in which: i v

Fig. 1 a diagrammatic and sectional view showing one form of the improved apparatus:

' g. 2 is a view similar to Fig. 1 but showing a second embodiment;

the accompanying drawings, forming a part of the' suction space. 1 Preferably, as is common practice with hydraulic governing apparatus, the inlet end of the suction conduit I 9 is formed with a mixing or combining cone or chamber 2| into which liquid furnished from the chamber I6 is discharged at high velocity from the jet 22.

.The servo-motor, at 12, comprises suitable housing structure 23 providing the operating cylinder 'and pilot valve bores 24 and 25 within which are disposed the operating piston 26 and the pilot valve 21, respectively.

The operating piston 26 is connected by a linkage, at 28, 'to the admission valve l3, and by a follow-up linkage, at 30, to the pilot valve 21.

The linkage, at 28, may comprise an operating.

piston rod 32, a..link 33, a lever 34, and a valve rod pivotally connectedtogether and the lever having a fulcrum 36; and the linkage, at 30, may

include the piston rod 32, the link 33, a fulcrumed leverfl, a link 38, and a compression spring 39 engaging the piston valve 21.

The structure 23 has passages 40 and 4| communicating with the operating cylinder bore 24 at either side of the operating piston 26 and communicating with the pilot valve bore through suitably located ports 42'and 43.. The pilot valve 2] has spaced enlargements 44 and 45 defining,- with the bore 25, aconnecting space or chamber 45-for the ports 42 and 43, and the enlargement 44 being arranged to cover more or less the port .42.

The pilot valve 21 has a piston face 41 at its lower end cooperating with the closed lower end of the pilot valve bore 25 to form the pressure chamber 48 connected by a conduit 49 to the impeller pressure space l6. Also, the upper end of the pilot valve bore 25v is preferably connected by a drain conduit to the reservoir 20.

The operating piston 26 divides the operating cylinder bore 24 into an expansible and contractible chamber or space 52 thereabove and a drain chamber or space 53 therebelow and forming a part of the drain space, the passages 40 and 4| communicating, respectively, with the chambers'52 and 53. The drain chamber 53 is connected to the drain conduit 54, also forming a part of the drain space and the operation of which will be more fully hereinafter set forth.

The constant flow valve, at 56, supplies liquid to the expansible and contractible chamber 52 conduit 55 and having'one or more lantern openings or ports 59 communicating with the space 60 at the downstream side of the second or variable orifices and communicating with the expansible and contractible chamber 52. A tubular member 6| is slida-ble'in the enlargement, the

forward portion thereof being formed to pro-. vide the fixed orifice '62 and the rearward end portion 63 thereof functioning as a slide valve to cover the opening or openings 59 to a variable extent in order to-provide the second or variable orifice. A spring 64 exerts its force on the tubular member in a direction tending to uncover the lantern opening or openings 59 and thereby to increase the flow area of the second orifice, the force of the spring being opposed by that of the differential of liquid pressure across the fixed orifice 62 and acting on the. annular piston-area provided by the forward end of the tubular mem-' ber 6|. The spring force is varied by adjustment means 51 acting therebelow, and the pilot valve 21 would occupy a position with the fluid and spring forces acting thereon in equilibrium, the portion 44 of the pilot valve covering the port 42 sufliciently to maintain the required pressure in the chamber 52 such that the outflow of liquid therefrom through the passage 40 will be equal to theinflow of liquid thereto which is constant from the passage 55. If the load should decrease, the speed and impeller pressure would increase, thereby upsetting the equilibrium condition of the pilot valve 21 and causing the latter to move upwardly, decreasing the restriction of the port 42 to provide for thesame;rate or discharge with a reduced pressure in the expansible and contractible chamber 52, the reduced pressure therein permits the then preponderating force of the spring means 51 to cause the operating piston 26 to move the motive fluid admission valve member IS in a closing direction. In addition to the increased force of compression of the spring 29' brought about by upward movement of thepilot valve 21. in response to increase in impeller pressure, the force of compression of the spring would further be increased concurrently with movement of the operating piston due to operation of the follow-up linkage, at 36, and movement of the operating piston 26 wouldcontinue until the equilibrium condition is again restored with the opening of the admission valve restricted suitably for the decrease in load.

If the load should increase, both the speed and impeller pressure would decrease, thereby upsetting the equilibrium of forces acting on the pilot valve 21,'the preponderating spring force moving the latter downwardly to further restrict the port 42, in consequence of which thepressure would build up in theexpansible and contractible chamber 52 and the operating piston would, on that account, be moved against the spring 51 to move the valve member IS in an opening direction. These operations would continue until an equilibrium condition is attained with the admission valve adjusted to proportion drain space, is preferably arranged to improve ch rge into the latter.

of thefollower 65. If the pressure at the down-' a stream side of the second or variable orifice should change, this would induce a pressurechange inthe spacebetween the orifices, thereby upsetting the differential across the first orifice,

' and the tubular member would move in such a direction as to give a compensating effect so as to maintain fiow through the two orifices substantially constant, irrespective of pressure variations at the downstream side'ofthe second or variable orifice.

. With the expansible and contractible chamber 52 of the operating cylinder supplied with liquid from the impeller through the conduit 55 and its constant flow valve, at 56, it will be apparent .that, with suitable operation of the pilot valve 21, the capacityexists for providing the necessary change in pressure in the expansible and contractible chamber 52 to provide for proper valve operation. Normally, 'for a given load, the piston 26 would occupy an equilibrium position with the force of fiuid pressure acting there-.

above in equilibrium with the force of the spring the suction effect of the impeller. Accordingly, it is formed so that its discharge end 66 is axially a nedwith the impeller and the eye for dis- Furthermore, where the liquid is lubricating oil, the drain conduit may be modified to provide a pressure source for bearing lubrication, in which event, as shown in Fig, 1, the drain conduit 54 would have first and second branches 61 and 66, the branch 61 having a spring loaded relief valve 69 and the discharge end 66 and the branch 66 leading to the bearings having a constant flow valve, at 16, similar to that already described.

The spring loaded relief valve operates to maintain a desired pressure at the upstream side thereof and-ahead ofthe constant flow valve, at 10, and the, latter operates to provide for constant flow with the maintenance of substantially constant pressure upstream thereof, irrespective of the downstream side thereof.

In Fig. 2, the expansible chamber or space, instead of beingprovidedentirely within the operating cylinder bone, as in Fig. 1, is provided partly therein, as shown at 52a, and partly, as shown at 52b, in a separate structure, at 12. In this view, the operating cylinder bore is divided into .sage 40a.

the expansible and contractible space or chamments 'of the admission valve independently of her 52a and the drain space or chamber 53a, and passages 40a and a join such spaces with the interior of 'the piston valve bore 250, the piston valve 21a having apiston enlargement a cooperating with the port end 42a of the'pasoperation with the bore 25a, provide a space for.

has an upper enlargement 45a,

connecting the ports 42a and 43a so that liquid may be transferred from the chamber 52a to the chamber 53a. In addition, the pilot valve I 21a has a lower enlargement 13, which, with the from the latter, liquid is conducted by the conduit 55b to the space 14.

The structure, at 12, provides a bore 16 within" which is disposed a piston 11, the latter dividing the bore into the expansible chamber 52b and the drain chamber 531}. A spring 18 in the chamber 53b exerts force on'the piston 11 in opposition to the force of fluid pressure applied thereto. The piston 11 has an opening 19 with which cooperates'the plug 80 depending from and adjustably carried by the top 8| of the structure, at 12, the plug having a lower tapered end 82 so thatdownward movement of the piston may be limited, the piston moving down wardly until the escape of liquid through the opening 19 is equal to that supplied to the chamber 52b by the constant flow valve, at 56a. By

adjusting the plug 80, the maximum volume of balanced by the upwardly-acting'spring force of I the chamber 52bv may be varied, its capacity preferably being at least about three-quarters of that of the operating cylinder. Y

In Fig. 2, impeller. pressure is supplied to the upper end of the pilot valve bore 25a by the conduit 49a, the drain conduit 51a being connected to the lower end of the bore.

Comparing Figs. 1 and 2, it will the operations of transferring liquid from the contractible and expansible spaces or chambers- 52 and 52a to the drain spaces or chambers 53 be seen that the rate atwhich motive liquid is supplied from the impeller. In this view, the accumulator featuresqare providedin the operating-cylinder.

,The'operating cylinder bore 24b of Fig. 4 is divided by the pistons 2 b and Ila intoexpansible'and contractible chambers 52c and 52d and the drain chamber 53c.

The piston "a has an opening 190 with which cooperates a plug 80a carried by theupper piston 26b. The spring means 51a is arranged between the pistons 26b and 11a 'andaspring 84 bears against the upper face of the piston 26h,

The'impeller pressure c nduit SSchas a constantv flow. valve, at 56b, discharging into the chamber 52d and the latter is connected, by the passage 55d, to'the piston valve space a, the piston valve construction being similar to that of Fig. 2, that is, with increase in impeller pressure due to decrease in load, the piston valve spaceltb' places the passages 40b and Mb in communication so that liquid may discharge from the chamber 520 into-the chamber 53c,

and, upon upward movement of. the piston valve, in consequence of increase in load, the. piston valve space 14o places thepassage 55d in communication with the passage 40!) to supply liquid from the accumulator space or chamber 52d to the chamber 520. I i

In order, that the operation of the construction shownin Fig. 4 may be better understood,'consideration should be given to the forcesacting on the composite piston arrangement constituted by the pistons 26b and Ha. Normally, the pistons would occupy an equilibrium position, the force of fluid pressure and the force of the spring 84 acting downwardly on the piston 26!) being thespring means 51a, and the force of the latter spring means acting downwardly on the piston 'Hawould be balanced by the upwardly-acting fluid pressureforce applied to the latter. Should the load decrease, the impeller pressure would increase, causing establishment of communication of the passages 40b and Mb to provide for transfer of liquid from the chamber 520 to the chamber 530; and, with these passages in communication and as the vforce of the spring means,

51a is greater than'that of the spring 84, the piston 261) would be moved upwardly to cause 17h]; admission valve to move in auclosing direci310 and 53a to secure rapid contraction of the contractible and expansible'chambers are the same.

On the other hand, the expanding movements. of these chambers are different. In Fig.1, the

rate at which the chamber 52 is-expanded de pends upon the rate of inflow and the extent of escape.

. Such upwardmovem'ent of the piston 26b a rate depending upon inflow from the constant flow valve 56b, the parts finally coming to rest Inv Fig. 2, opening of the admission valve is much more rapid for the reason that.

the supply of liquid accumulated in the charm ber 52b is available for transfer to the space 5241 to secure rapid expansion of the latter with downward movement thereof and movement of the admission valve in an opening directionv when the conduit 55b is placed in communication with the port 42a by the piston valve nection with Fig, 1.

Fig. 4 is fundamentally similar to Fig. 2 in that accumulator .and liquid transfer features provide for rapid opening and closing movewith restriction of the admission valve suitable I for thereduced load and with the various forces acting on the piston valve 21b and on the pistons 7' 26b and 'l'la-in balance. If the load should increase, the piston valve. 21b would move upwardly,

.placing the space 14a in communication with the port 42b, whereby liquid may flow rapidly from the chamber 52d to .thechamber v52c to move the operating piston 26b downwardly to open the admission valve wider, the flow of liquid for'ithis purpose dependingupon the relatively greater; force of the spring means 51a as compared'to that of the spring 84. While this operation involvesthe piston: 1111 moving downwardly relatively to the upper piston 26b, as the chamber 52d. is continuously supplied with liquid by the l constant flow'valvaat 56b, it will be restored to correct relative position. .The pistons 26b and l la' continue-to move with opening of the admission valve until the latter is opened sufliciently for the increase in load and equilibrium of the 'various forces acting on the piston valve 21b and on the pistons 26b and "a are restored. Movement of the operating piston transmitted by the follow-up linkage changes the spring force acting on the pilot valve until, such force is in balance with the impeller pressure force acting thereon and with the pilot valve in its neutral ornormal position. Also, liquid is supplied from the constant flow valve, at 561), until'the lower constant-flow device utilizing fluid delivered by the impeller under regulating pressure to provide motive fluid for the operating member of the servo-motor.

4. The combination with a prime mover having an admission valve, of a servo-motor including an operating member connected to the admission piston 11a is restored to its-normal position relatively to the upper piston 26b, movement of the lower-piston ceasing with forces acting thereon in balance andwith inflow of liquid to the charm ber52d equal-to outflow therefrom. In this connection, it will be noted that the accumulator capacity of the chamber SM is limited by the plug 80a cooperating with the opening 19a of the piston 1121; the piston moving upwardly until discharge through the opening 19a is equal to that of supply through the constant flow. valve From the foregoing, it will-be apparent that there is provided a servo-motor whose operating piston is moved by liquid furnished from the impeller without impairing the eficacy. of the latter to provide speed-responsive or controlling pressure on the pilot valve.

While the invention has been shown in several forms it will be obvious tothose skilled in the art that it is notso limited, but is susceptible of various other changes and modifications without departing from the spirit thereof, and it is desired, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What is claimed is; v l 1. In a hydraulic governing systemfor a prime 'mover having a controlling element, means providing fluid under pressure varying as a function,

valve and a pressure-responsive pilot valve controlling the'application of inelastic motive fluid to the operating member, an impeller driven by the prime mover and providing inelastic fluid under regulating pressure varying as a function of the speed of the latter, means for applying fluid under regulating pressure to the pressureresponsive pilot valve, means including a con-- stant-flow device utilizing fluid under regulating pressure to' provide motive fluid for the operating member of the servo-motor, and means utilizing fluid exhausted from the servo-motor to improve the suction lift of the impeller.

5. In hydraulic governing apparatus, an impeller including a runner and a casing, an operating cylinder, an operating piston in the cylmder, -means providing motive liquid for the operating cylinder including a conduit connected to the impeller casing, means providing for constant flow through the conduit from the impeller, means for securing operation of the operating piston in the operating cylinderand including a pressure-responsive pilot valvecontrolling the application of motive liquid to the latter, and means including a conduit connected to the impeller casing for applying impeller pressure to the pressure-responsive pilot valve.

6. In hydraulic governing apparatus, an impeller for developing oil under pressure and including a runner and a casing, an operating cylinder, an'operating piston in the cylinder,

of the prime mover speed and including a centrifugal impeller driven by the prime mover, hydraulic operating mechanism for the controlling element, means responsive to pressure pro vided by the impeller for controlling said mechanism, and means including a constant-flow device for supplying fluid from the impeller for motivation of the hydraulic operating mechanism.

2. The combination with a prime mover having an admission valve, of a motor device including an operating movable member connected to the admission valve and pressureresponsive means for controlling the application of inelastic motive fluid to the operating member to secure move-' ment thereof, means operated by the prime means providing motive oil for the operating cylinder including a first conduit connected to the impeller casing, means providing for constant flow through the conduit from the impeller, means for securing operation of the operating i piston in the operating cylinder and including a mover to provide inelastic fluid under regulating pressure varying as a function of the speed of the prime mover,- means for applying fluid under regulating pressure to the pressure-responsive means, and means including a constant flow device utilizing fluid under regulating pressure to provide motivating fluid for the operating 'viding for constant flow from the impeller pressure-responsive-pilot valve controlling the application of motive oil to the latter, means iricluding a second conduit connected to the im-= peller casing for applying oil under impeller pressure to the pressure-responsive pilot valve, .athlrd conduit for oil discharging from the servo-motor, a constant flow valve in the third conduit, and means including a relief valve for maintaining a substantiall constant r ahead of the constant flow vilve. p esure 7. In hydraulic governing apparatus, an impeller including a runner and a casing, said casing having an eye aligned axially with the runner, a' suction conduit communicating with Y the eye, an operating cylinder, an operating pis-' ton in the cylinder, means providing motive liquid for the operating cylinder including a conduit connected to the impeller casing, means prothrough the conduit, means for securing operation of the operating piston in the operating cylinder and including a pressure-responsive pilot valve controllingapplication of motive liquid to the latter, means including a conduit connected to the impeller casing for applying impeller pressure to the pressure-responsive pilot valve, means including a conduit for liquid exhausted from the operating cylinder, said last-named conduit comprising first and second branches, a valve inthe first branch for maintaining a constant pressure ahead thereof and providing for flow'therethrough of liquid in excess of that-required for the pressure, said first branch having its discharge end communicating with the suction conduitand aligned with the impeller eye, and means providing for constant flow through the second.

branch.

8. In hydraulic governing apparatus, an impeller including a runner and a casing providing a pressure space, an operating cylinder, an operating piston in the cylinder, a first conduit for supplying liquid from the impeller pressure space to the space of said operating cylinder at one side of the operating piston, a constant flow valve in said conduit, spring means exerting force on the other side of the operating piston, a pilot valve for controlling the discharge of liquid from the space at the first side of the operating piston, means for controlling the pilot valve including a necting the latter .with said first chamber and with said drain space; a pilot valve movable in said pilot valv'e chamber to control communication-of said passages; means including a pressure-responsive device for moving the pilot valve; a device for producing pressure of liquid varying as a function of speed andhaving a pressure space; means including a first conduit for connecting said pressure space with said contractible pressure-responsive device, and a second conduit connecting the impeller pressure space with the pressure-responsivedevice.

9. In hydraulic governing apparatus, an impeller including a runner. and a casing providing pressure and suction spaces, a suction conduit forthe suctionspace, an operating cylinder, an operating piston in the cylinder, a second conduit for, supplying liquid from the impeller pressure space to the space of said operating cylinder at one side of the'operating piston, a constant flow.

valve in said conduit, spring means exerting force on the other side of the operating piston, a pilot valve for controlling the flow of liquid from. the space at the first side of the operating piston to the space at the otherside thereof,-

means for controlling'the pilot valve including a pressure-responsive device, a third conduit connecting the impeller pressure space with the pressure-responsive device, and a drainage conduit communicating with the space of the operatingcylinder at said other side of the operating piston and having its discharge end communicating with the suction conduit and directed toward the suction space of the impeller in order to improve the suction lift of the latter.

10. In hydraulic governing apparatus, an impeller including a runner and a casing providing a pressure space, an operating'cylinder, an operating piston in the cylinder, a firstconduit and expansible chamber; a constant-flow valve in said first conduit; and a second conduit for connecting said pressure space with said presviding a piston valve bore and first, second and third passages connecting the latter with the drain space,'the first expansible and contracti-ble space, and the second expansible and contractible space, "respectively; a piston valve in said bore and movable to place said second passage in communication either with the first passage or with 'the third passage and to interrupt such v communication; said piston valve having a piston faceicooperating with the bore to provide apressure chamber; means for throttling escape of liquid from said second expansible and contractible space to the drain space such that, with expansion of' the second space beyond a prede-, termined point, the resistance to escape is very substantially reduced; a device for producing pressure of liquid varying as a function of speed and having pressure and suction spaces; second conduit; a first linkage connecting said first pisfor supplying liquid from the impeller'pressure Y space to the space of said operating cylinder at one side of the operating piston, a constant flow valve in said conduit, spring means exerting force on the other side of the operating piston, a pilot valve for controlling the fiow of liquid from the space at the first side of the operating piston to the space at said other side thereof, means for controlling the pilot valve including a pressure-responsive device, a second conduit connecting the impeller pressure space with the pressure-responsive device, a drainage conduit communicating with the space of the operating opposes that of liquid pressure applied to the pis-.

and third conduits forconnecting said pressure space with said second contractibleand expansible space and with'said pressure chamber, re-

spectively; a constant-flow valve in the second ton with the admission valve; a second linkage connecting the first piston with the piston valve and including a spring so disposed that its force ton valve piston face. 5

13.- The combination with a prime mover having an admission valve, of an operating cylinder, an operating piston in the 'cylinder and connected to the admission valve, biasing means acting on the operating piston to move the admission valve in a closing direction, anaccumulator, meansoperated by the prime mover to provide liquid under regulating pressure varying cylinder at said other side of the operating pis ton, a constant fiow valve in the drainage conduit, and means including a relief valve for P maintaining a substantially constantpressure in f the drainage conduit ahead of the constant fiow valve.

v 11. In hydraulic apparatus for controlling the position of a prime mover motive fluid admission valve, means providing a drain space; means including an operating piston defining an expansible and contractible chamber; spring means exerting its force on the operating piston in a direction to contract said chamber; means providing a pilot valve chamber and passages conas a function of the speed of the latter, a con- ,dui't for delivering liquid from the last-named means to the accumulator, means providing for constant fiow through the conduit, means providing a pilot valve bore, a first passage connecting the pilot valve bore to the operating cylinder to supply liquid to the latter to act onthe operating piston against the force of the biasing means to move the admission valve in an opening directioma second passage connected to the bore and providing a part of the drainage space, a third passage connecting the accumulator and the bore,a pilot valve movable in the bore to connect said first passage either with the second passage or with the third passage, means including pressure-responsive means for moving the pilot valve, and a conduit for supplying liquid under regulating pressure from said regulating pressure developing means to the pressure-responsive means.

14. The combination with a prime mover having an admission valve, of an operating cylinder, an operating piston in the cylinder and connected to the admission valve, biasing means acting on the operating piston to move the admission valve ln a closing direction, an accumulator, means operatedby the prime mover to provide liquid under regulating pressure varying as I a function of the speed of the latter, aconduit for delivering liquid from the last-named means to the accumulator, means providing for constant flow through the conduit, means providing a pilot valve bore, a first'passage connecting the pilot valve bore to the operating cylinder to supply fluid to the latter to act on the operating piston against the force of the biasing means to move the admission valve in an opening direction, a second passage connected to the bore and providing a part of the-drainage space, a third passage connecting the accumulator and the bore, a pilot valve movable in the bore to connect said first passage either with the second passage or with the third passage, pressure-responsive means for the pilot valve comprised by a piston face formed on the latter and a portion of the bore, a conduit for supplying liquid under regulating pressure from said regulating pressuredeveloping means to the pressure-responsive means, means providing for escape of liquid from the accumulator so that liquid may accumulate therein to a predetermined volumetric extent, and follow-up means connecting the operating piston and the pilot valve.

15. The combination with a prime mover having an admission valve; of an operating cylinder; an operating piston in the cylinder and connected to the admission valve; biasing means exerting force on the operating piston to move the admission valve in a closing direction; said operating piston separating the interior of the operating cylinder into a liquid pressure space and a drain space portion with the liquid pressure space so arranged that, 'with the admission of liquid under pressure thereto, the force thereof acts on the operating piston to move the latter against the force of the biasing means to move the admission valve in an opening direction; an accumulator cylinder; an accumulator piston in the accumulator cylinder and cooperating with the latter to provide an accumulator liquid pressure space; biasing means acting on the accumulator piston to contract said accumulator liquid pressure space; an impeller operated by the prime mover to provide liquid under pressure varying as a function of the speed of the latter, said impeller including a casing cooperating with a runner to provide a liquid pressure space; a conduit for delivering liquid from the impeller pressure space to the accumulator pressure space; aconstant-flow valve in said conduit; means providing a pilot valve bore; a first passage connecting the pilot valve bore to the operating cylinder pressure space; a second passage connecting the bore and the drain space portion responsive means for the pilot' valve comprised by a piston face formed on the latter and a portion of the bore; a conduit for supplying liquid from the impeller pressure space to the pressure-responsive means; means providing for escape of liquid from the accumulator pressure space so that a predetermined volume of liquid'may acposition of a prime mover motive fluid admisof the operating cylinder; a third passage connecting the bore and the accumulator pressure sion valve, means providing a drain space; means including an operating piston defining an expansible and contractible chamber spring means exerting its force on the operating piston in a direction to contract said chamber; 'means providing a pilot valves-bore and passages connecting the bore with said-chamber and with said drain space; a pilot valve-movable in said bore to control communication of said passages; said pilot valve having a piston face cooperating with said bore to provide a pressure chamber; a de-' vice for producing pressure of liquid varying as a'function of speed and having a pressure space;

means including a first conduit for connecting said pressure space with said contractible and expansible chamber; a constant flow valve in said first conduit; a second conduit for connecting said pressure space with said pressure chamber; a first linkage connecting the operating piston and the admission valve; and a second linkage connecting the operating piston and the pilot valve and including a spring so disposed that its force opposes that of liquid pressure applied to the pilot valve piston face,

17. In hydraulic apparatus for controlling the position of a prime mover motive fluid admission valve, means including a first conduit providing a drain space; means including an operating piston defining an expansible and contractible chamber; spring means exerting its force on the operating piston in a direction to contract said chamber; means providing a pilot valve bore and-passages connecting the latter with said chamber and with said drain space; a pilot valve movable in said bore to control communication of said passages; said pilot valve having a pistonv face cooperating with said bore to provide a pressure chamber; a device for producing pressure of liquid varying as a function of speed and including an impeller and a casing therefor; said casing defining suction and pressure spaces and having an eye axially aligned with the impeller and opening into the suction space; means including a second conduit for connecting said pressure space with said contractible and expansible chamber; a constant flow valve in said second conduit; a third conduit for connecting said pressure space with said pressure chamber; a suction conduit connected to the eye of the impeller casing; said first conduit having its discharge end opening into the suction conduit and directed axially toward the eye of the impeller casing so as to assist the suction lift of the impeller; a first linkage connecting the operating piston and the admission valve; and a second linkage connecting the operating piston and the pilot valve and including a spring so disposed that its force opposes that of liquid pressure applied to the pilot valve piston face.

18. In hydraulic apparatus for controlling the position of a prime mover motive fluid admission valve, means. including a first conduit providing a drain space; means including an operating piston defining an expansible and contractible chamber; spring 'means exerting its force on the operating piston in a direction to contract said chamber; means providing a pilot valve bore and passages connecting the bore with said chamber and with said drain space; a pilot valve movable in said bore to control communication of said passages; said pilot valve having a. piston face cooperating with said bore to provide a pressure chamber; a device for producing pressure of liquid varying as a function of speed and having flow valve in said second conduit; a third conduit for connecting said pressure space with said pressure charhber; a first linkage connecting the operating piston and the admission valve: a

apressure space; means including a second conduit for connecting said pressure space with said contractible and expansible chamber; a constant second linkage connecting the-operating piston and the pilot valve and including a spring so disposed-that its force opposes that of liquid pressure applied to the pilot valve piston facef a through oi liquid in excess of. that required for the pressure. a

'HENRY' F.

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