US2612838A - Fluid pressure control apparatus - Google Patents

Description

Oct. 7, 1952 a. R.. NjcHoLs 2,612,838

Y FLUID PRESSURE CONTROL APPARATUS Filed March l,v 1949 f llllll 60 3 f Je? Z .2l 5 3/ 7 l 47 34 32 Y o 45 v g5 e l.. 55 "30 -r 46 6./ /3

50 .2 f e Z @a 5 24 3 J3 4 6 44 H 2z a l /4 48 Z/ /7 e :Lz-' 6a.'l lllllh--Pv i L lr 0 52a Y 25a. '1 47a 34a 32 o 45a `3a L l 30 6 l 26. 4 5,4 o g 371 50a -/5a 43d 55 ga 241 .f5a 44a l 22 25a 3a 8 Z/a 4 a /a ai I @MMO/1 Patented ct. 7, 1952 iv claiiiisi (cl. loaf-fill) The present invention relates to Alil pumping units -for supplying oil pressure 'to hydraulic turbine governors or other apparatus using fluid under pressure Iand particularly 'to means for shiftii the Vpre'ss'l'iife 'operating range of an individual pumping unit, 'and the 'principal object fof the 'invention isfthe provision of new and..iniprved apparatus of these types,

Where two oil pumping unit `s ar used on modern hydraulic turbine 'governor systems, the equipment is l'i'su'ally 'arranged so that the" pumpsare started and stopped 'separately by 'their ref sp'ctive pu'mp c'ciii'rel mescjs. 1siic'li-me'aiis herein characterized by a limit `swit ch pla'ced in each lpui-zip motor starter Vcfofii'i'jr'ol circuit and an unloadr valve which inechanic'allyfoperates such switch. The arrangement is su'ntnattn'e 'motor will stop when slichunl'oaier valve opens and siert when the unleade'r val've 'starts le close.

When this system is lised, it ifs customary `to siifa'ilgc ycontrols 'cli `the pilot valves, which acrmt receiver pressure to their respective unloading 'val've'swhen such pressureattains a pr'e'- determined value, such that the operating range of each lllz'iloa'de'r Valve may be separatelysh ted.

Thus, 'one pump will operate automatically the normal pressure 'rance andthe other; pump will roperate 'automatically at a lower or st'al'i'cl-v byfrange l. Y A,

An 'object f this inventionis' to` provide Ineens remotely controllable whereby the pressures 'at which 'a pilot valve' is to be actllatedinay loev remotely selected, "so that iii the caseV of a turbine governor'. for example, 'the governor be located at' a lowlevel, or, in general', at soli'le remote place.` Another object is to provide a vill'ligclpiii-g unit having means, remotely controllable, Afor' shifting' the pressrelrange at which such unit operates: Another object is to' providene'w and improved dual 'pumping' systems, in which one of the'pump; lngjunits operates at a normal/pressure range while the other unit operates 'at' a lower or standby pressure renee, such that upon failure" of. the former linit the latter iliiituwillV 'autom cally maintain the receiver pressure within the lcw'e'r range until shifted tothe higher orner: malv range by raiilal remote' control means. n

Other bjects `willl appear hereinafter' as the description of the invrt pfeeds. w The noif'l features f theiiivention and how the Yobjcll's are attained will appear fully froi'. this' specification and the accompanying dw'ii showing' one embodiment of' the intentiorl and fri'i'ii a part dfths application, and

Y 2 all Lof thesenovel restores are pointed out inthe claims,

Referring to the drawing, a 1scheinatic fel L tion partly in section of two identical 'ilPlm ing units, is shown, havingf'a coinnlodre'ceiver' and controllable from a com oiicontjrol panel which may be remotely pla `d 'fro'rrif the li- A description of the oil pumping` "nit in theupp'er part lofthe drawing' will both, it being notedshai-iliepartsoith pump;-` inglinit shown in the lower part o' the di 'awi e corresponding t'of part` s of tl 1^e up' r1 'isis-'stes is beengiventhe same reference numerals but thesumxa'.

The fluid pumping meansterized by oil pump I and driving electric motor 2 andUcirciiilt 3Q means delivers ilui'd from slinip Q throl'i'g-l'ifo duits 5 and '6, tothe receiver `1 whi'c1ri f siippli hydraulic turbine governor system 1 slij` or any other system with fliid i 1 through pipe l|l. Re`ceiver`- pressue municatedthrough conduit Ill t`c the'pl lot means', herein characterized by pilot valve esserti ly 2; the actuation pressure of vviiiclijis vdeieim ii by remotely controllable adjusting means, herein characterized by bla-sing piston 1 3, ilpoli act tion of the pilot means ,receiver pres" pump `control means, herein characterized by the unloading valve assembly M which iurictiorlsto' prevent further discharge tothe receiver 'I bythe pumpingmeans andinitia'te's siih discliaifge to the receiver 1 upon the reversed actuation o'f the pilot means.

The pilotmeans comprises the pilot valve iassembly l2 having a pilot valve casing l5 sited with a diierentialtwo-#spoled pilot valve i6 re:Y` sponsive ,to receiver pressure thrlilgli" va p'it 4I1 against the force' of biasing means herein charla' acterized by resilientman's: A po'r`t12l i's'vcon'-4 nccicd to thev uiileadiiig assembly nl thioiielil a conduit 2zl and a port 231perr`riitsl trapped fluid to exhaust to the sump' 4 through al conduit 24;.

The adjusting' means', comprising-clic biasing` piston l 3 reciprocable in the upper iia'rt tlf-ith'e valve casing for varying the force lexerted by' the resilient means it,y is remotely controllable; The upper part ofthe pilot Vvalve casing" i5" is: bored somewhat larger than the lower part and receives the rbiasing pistol; la wbicli cnipiisesj a: iiciiil'A fitting inthe larger bere and stem lining? 3 of the port I'I such that the pilot valve I6 will respond to two predetermined receiver pressures depending on whether the biasing piston I3 is in a raised or lowered position. The area of the smaller bore, in which the pilot valve I6 is fitted, with respect to the area of the port I'I determines the pressure range between opening and closing of the valve. The purpose of utilizing differential bores in the pilot valve casing I is to permit the option of using receiver` pressure rather than fluid pressure from an outside source to force the biasing piston I3 to its lower position.

The remote control means shown herein comprises a three-spooled control valve having an ex-tended stem secured to a solenoid core 26 at the lower end and a spring 21 for moving the valve to its deenergized position at the upper end. Such valve 25 is fitted into a control valve casing 30 having ports 3| and 32 which are in communication to allow receiver pressure to force the biasing piston I3 to its lower position, when the solenoid 26 is energized, through the conduits 33 and 34; and a port 35 which is in communication with the port 32 when the solenoid 26 is deenergized to allow the biasing piston I3 to raise and exhaust the fluid to the sump 4 through the conduits 34 and 36. The solenoids 26 and 26a are alternately energizable by a double -throw switch 31 mounted on a control panel 40 located remotely from the control valves 25 and 25a. The control panel 40 may also have mounted thereon a pressure gauge 4I to indicate receiver pressure, and a receiver pressure responsive electric bell 42 which may be adjusted to sound an alarm when the receiver pressure drops to predetermined value.

The pump control means comprises an unloading valve assembly I4 having a two-spool unloading valve 43 fitted into the unloading valve casing 44 and a port 48 which admits receiver pressure from the pilot valve assemblyv I2. A stem 45 extending from the unloading valve 43 is operably connected to a switch 46 in the pump motor control circuit 3 by means of a lever 41 such that upon the unloading valve 43 lifting, the circuit will be broken stopping the motor 2 and pump I. The raised position of the unloading valve 43 allows ports 50 and 5I to communicate which permits the pump I to unload by draining the trapped fluid to the sump 4 through the conduits 53 and 53. A check valve 54 in the conduit 6 prevents loss of receiver pressure when the pump I is not operating.

While two sumps 4. 4a have been shown, for the sake of clarity, it will be obviousA that only a single sump is required.

The operation of the described embodiment of the invention is as follows:

Assume that the pilot valve assemblies I5 and I5a of the respective units have been designed such that when the respective biasing piston I3 or I3a is in its lower position, the normal pressure range of the respective unit will be 275-300 p. s. i. and that when the respective piston is in its upper position the standby range of the respective unit will be 250-275 p. s. i. Assume that the pressure responsive device 55 is adjusted to close the bell circuit 56 when the receiver pressure 1s less than 270 p. s. i.

Before the pumping units are put into operation, the double-throw switch 37 is in a .neutral position, the switch 51 in the bell circuit 1s open, the hand operated switches 60 and 60a in the respective motor control circuits 3 and 3a are open and as there is no pressure in the receiver 4 'I the switches 46 and 46a operated by the respective unloader valves 43 and 43a are closed.

Assuming that the upper unit on the drawing is to operate in the normal range, the switches 60 and 60a are closed which respectively causes both pumps I and Ia to operate, .and the doublethrow switch 31 is thrown to close the upper solenoid circuit 51 causing the upper control valve 25 to move to its lower position allowing receiver pressure to be communicated to the large bore of the upper pilot valve casing I5. As the receiver pressure increases the upper biasing piston I3 will be forced to its lower position.

When the receiver pressure reaches 275 p. s. i., the lower pilot valve I6a will respond causing the unloader valve 43a to unload and stop the pump Ia. At this pressure the bell circuit switch 51 may be closed. The upper pumping unit will then function to maintain the receiver pressure between 275-300 p. s. i. The parts are then in the position shown in the drawing.

If the upper pumping unit should fail, the receiver pressure will drop and upon reaching 270 p. s. i. the bell 42 will ring warning the operator of the failure at which time he can close the lower solenoid circuit 51a by means of the doublethrow switch 3'1 so as to shift the range of the lower unit from the standby range (250-275 p. s. i.) to the normal range (275-300 p. s. i.). If for any reason the operator does not so shift the lower unit, it will automatically begin to pump fluid when the receiver pressure drops below 250 p. s. i. and will continue to operate in the standby range indefinitely.

The pressures herein referred to have been given by way of illustration and not limitation. it being obvious that other pressures may be used.

From the foregoing it will be apparent to those skilled in the art that the illustrated embodiment of the invention provides a new and improved control for pressure responsive devices and accordingly accomplishes the objects of the invention. On the other hand, it will also be obvious to those skilled in the art that the illustrated embodiment of the invention may be variously changed andmodied without departing from the spirit of the invention and accordingly the disclosure herein is illustrative only, and the invention is not limited thereto.

It is claimed and desired to secure by Letters Patent:

l. A dual pumping system wherein two pumping units supply fluid under pressure to a common conduit and each pumping unit comprises;

iluid pumping means, pilot valve means responsive to the pumping means discharge pressure, biasing means resisting actuation of said pilot valve means, adjusting means having a first position whereby a predetermined resistance is imparted to said biasing means and a second position whereby a relatively greater resistance ls imparted to said biasing means, and pump control means actuable upon actuation of said pilot valve means for preventing discharge of said pumping means into said common conduit; the combination with said pumping units of means remotely controllable for selectively moving the adjusting means of either of said pumping units to said first position or to said second position.

2. A dual pumping system wherein two pumping units supply fluid under pressure to a common conduit and each pumping unit comprises; fluid pumping means, pilot valve means responsive to the pumping means discharge pressure, resilient means resisting actuation of said pilot valve means, adjusting means having a rst position whereby a predetermined resistance is imparted to said resilient means and a second position whereby a relatively greater resistance is imparted to said resilient means, and pump control means actuable upon actuation of said pilot valve means for preventing discharge of said pumping means into said common conduit; the combination with said pumping units of means remotely controllable for selectively moving the adjusting means of either of said pumping units to said rst positi-on and concurrently the adjusting means of the other of said pumping units to said second position.

3. A dual pumping system wherein two pumping units supply uid under pressure to a common conduit and each pumping unit comprises; fluid pumping means, pilot valve means responsive to the pumping means discharge pressure, resilient means resisting actuation of said pilot valve means, adjusting means having a standby position whereby a predetermined resistance is imparted to said resilient means and a normal operating position whereby a relatively greater resistance is impar-ted to said resilient means. and pump control means actuable upon actuationof pilot valve means for preventing discharge of said pumping means into said common conduit; the combination with said pumping units of means remotely controllable for selectively moving the adjusting means of either of said pumping units to said standby position and concurrently the adjusting means of the other of said pumping units to said normal operating position.

4. A dual pumping system wherein two pumping units supply fluid under pressure to a. com- 6 mon conduit and each pumping unit comprises; fluid pumping means, pilot valve means responsive to the pumping means discharge pressure, resilient means resisting actuation of said pilot valve means, a cylinder and a biasing piston movable in said cylinder to vary the resistance of said resilient means, said piston having a standby position whereby a predetermined resistance is imparted to said resilient means and a normal operating position whereby a relatively greater resistance is imparted to said resilient means, and pump control means actuable upon actuation of said pilot valve means for preventing discharge of said pumping means into said c-ommon conduit; the combination with said pumping units of control valve means remotely controllable ,for supplying fluid under pressure to said cylinder for moving the biasing piston of either of said pumping units to said normal operating position and concurrently the biasing'piston of the other of said pumping units to said standby operating position.

BEVERLY R. NICHOLS.

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

UNITED STATES PATENTS

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