US2747598A

US2747598A - Liquid-dispensing system with remote control

Info

Publication number: US2747598A
Application number: US300183A
Authority: US
Inventors: Wooldridge James Arthur
Original assignee: Shell Development Co
Current assignee: Shell Development Co
Priority date: 1951-07-31
Filing date: 1952-07-22
Publication date: 1956-05-29
Anticipated expiration: 1973-05-29

Description

May 29, 1956 J. A. WOOLDRIDGE LTQUTO-OISPENSING SYSTEM WITH REMOTE CONTROL 2 Sheets-Sheet Filed July 22, 1952 May 29, 1956 J. A. WOOLDRIDGE 2,747,598

LIQUID-DISPENSTNG SYSTEM WITH REMOTE CONTROL Filed July 22, 1952 2 sheets-snaai 2 Fig. 3

atent 2,747,598 Patented May 29, 1956 LIQUID-DISPENSIN G SYSTEM WTH REMOTE CNTRL James Arthur Wooldridge, Great St. Helens, London, England, assignerV to Shell Development Company, Emeryville, Calif., a corporation of Delaware Application July 22, 1952, Serial No. 300,183

Claims priority, application Great Britain July 31, 1951 19 Claims. (Cl. 137-193) This invention relates to Vliquid-dispensing systems of the kind in which a pump delivers liquid into a line having-a delivery valve at one or more dispensing points remote from the pump. The invention is especially applicable to the so-called static systems for fuelling aircraft, in which fuel is fed by a pump from a static bulk storage tank through a permanent system of pipes to a number of dispensing stations located adjacent the parking positions of the Vaircraft and equipped withl dispensing devices. The dispensing devices, each of which is controlled by a delivery valve, are'generally remote from the bulli storage tank and the pump, the latter usually being situated adjacent the tank.

The discharge of fuel at the dispensing stations is necessarily intermittent, and at the less `busy aerodromes there are frequent periods when the delivery valve or valves are closed. Unless an operator is stationed `at the pump house to start and stop the pump as required, the pump operates for substantial periods of time against the pressure exerted by the usual relief or by-pass valve with whichV such pumps are provided, with the result that unnecessary power consumption and wear'and tear take place. W'hilst an electrically driven pump could be controlled by the operator at the dispensing station, this woud necessitate the provision of a control circuit to each trol rack and starter motor of the engine, but again the necessary control circuit must be extended to each dispensing station. A further and more serious diiculty in the case of a diesel engine, especially where trac conditions on the aerodrome are such that the engine would be started and stopped frequently, is the wear and tear on the engine associated with such starting and stopping.

An object of the present invention'is to provide a system whereby the load on the pump is reduced automatically, whenever the delivery valve or allv ofvthem is or are closed, to a valueV substantiallybelow that allowed by the relief or by-pass valves hitherto provided and without the necessity for stopping the prime moverwhich drives the pump.

According to the present invention a liquid-dispensingV system includes a pump, a delivery line connecting thedischarge side of said pump to at least one dispensing devicev controlled by a delivery valve, a non-return valve in said delivery line, said non-return valve permitting liquid 'flow from said pump to the dispensinggdevice or devices but not viceversa, vand a by-pass line providing 'a path between the discharge and suction sides of said Y pump through a by-pass valve which is operative to vary the resistance to liquid flow offered by said by-pass line delivery valve or valves and to afford a low-resistance by-pass toY said pump when -the pressure at said point in the v'deli-veryline reaches'a predetermined value.i

Preferably the system also includes a pressure-storage vessel communicating with said delivery line at a point" between said non-return valve and the delivery valve orV valves.

The by-pass valve preferably includes a main valve member, the position of which determines the resistance' to liquid flow oifered by the by-pass line, and a pilot valve acted upon by the pressure at Said point in the delivery line between the non-return valve and the delivery'valve or valves, which pressure tends progressively to open' said pilot valve against aV force biasing said pilot valve` to the closed position to vary the position of said main' valve member, the disposition of said main valveY mem:v ber being such as to close said by-pass line whensaidn pilot valve is closed.

The pilot valve preferably functions in such a man;` i

ner as to cause the main valve member progressively/'td reduce the resistance to liquid flow Voffered by the by-passl line until the pressure at said point in the delivery line reaches a predetermined value above which said pilot4` valve causes said main valve member to open fully" to provide a low-resistance by-pass to the pump. v

The main valve member may serve in its closed position to separate two portions of a chamber housing said'A main valve member, in one of which portions operates a". piston connected to and of larger surface area than said` main valve member, means being provided whereby; on A operation of the pilot valve, the liquid pressure acting on the side of the piston adjacent the main valve :meme ber is progressively transmitted so as to act on both sides ofv saidpistonl to open said main valve member, andk whereby on closure `of said pilot valve the liquid pressure on the piston face remote from the main valve mem-*- ber is bled away to close said main valve member.

Advantageously the arrangement is such that the pilotv valve when fully opened is caused to move to the closed position only when the pressure at said point in the delivery line falls to a value below that causingwinitialf opening thereof.

Conveniently, the delivery line is provided with a ven-V turi constriction at the said point between the non-gi return valveand the delivery valve or vales at which'V the pressure is determined and the by-pass valve is ar-V ranged to open fully only when liquid ow through theventuri constriction is substantially zero.

A static fuelling system for aircraft in accordance with.y the invention will now be described by way of example and with reference to the accompanying drawings ,forni-t. ing a part of this specification, in which:

Figure 'l is a diagrammatic general arrangement view of a dispensing system according to the invention; l

Figure 2 Yis an elevation view of a part of the dispensing system, namely that pertaining to the pump,i

- and its by-pass valve, parts being shown diagrammati-V cally; and

Figure 3 is a detailed sectional view of the by-pass valve.

Referring first to Figure l, the complete system inf. cludes the following principal elements:` a source Y of v liquid, such as a bulli storage 'tank or reservoir 6 from which liquid flows to a supply pipe i which mayhave a shut-ofvalve a pump 9 having the suction thereof^` connected to the supply pipe 7 and drivenby any suitable l motor 10, such as a diesel engine which may be'provided with the usual governor for controlling the supply of fuel v theretoin accordance with the load; a by-pass line hav` ing serially connected parts lfm, 1lb, interconnecting e the suction and pressure discharge sides of the pump; a ow control valve l2 in the by-pass line; a pressure` delivery pipe line i3 having a check or non-return valve 14 disposed to permit ow only away from the pump;'.one

or more dispensing outlets 15, a, etc., which may be located at dilerent dispensing stations of the aireld or other dispensing installation, for example in pits as shown, and which are connected to the delivery pipepline by suitable branches thereof, each dispensing outlet including at least a delivery shut-off valve 16, 16a, etc., and, if desired, either a coupling device 17, 17a, etc., for attaching a hose 18 fitted with a suitable nozzle 19Y for attachment to the fuel tank of an aircraft, or merely a permanently attached hose; and a. pressure-responsive actuating device for operating the flow control valve 12 in the by-pass line in accordance with the pressure in the delivery pipe line downstream of the check valve 14, said actuating device including a valve actuator 20 and a pressure-responsive element, which may be simply a tap 21 in communication with the interior of the pipe line 13,-and further connected to the actuator 243 by any suitable'device for transmitting a signal corresponding to the prevailing pressure, represented diagrammatically as a transmission line 22, it being understood that the latter may be merely an electrical cable. ln its broadest aspect, the element 21 is any device for sensing the pressure in the pipe line 13 and the line 22 is any hydraulic, pneumatic, electrical, etc., device for transmitting the sensing; however, as will be explained in detail in connection with the specific embodiment of Figs. 2 and 3, it is preferred to have this element respond not only to the static pressure but also to the velocity of liquid ow in the line 13, to indicate a lower pressure upon an increase of iiow. The actuator 20 is arranged to open the valve 12 either progressively or completely'upon a rise in the indicated pressure above a predetermined value and to close the valve upon a fall in pressure, and the valve 12 is preferably of the type offering as low a ow resistance as practicable to the passage of liquid when fully open. Preferably, although optionally, the delivery pipe line 13 is provided at a point therein downstream of the check valve 14 with a pressure-storage vessel or reservoir 23 of any suitable type, such as one containing a compressed gas in direct contact with the liquid or isolated therefrom by a diaphragm, a gas bag, etc., as are well known in the art.

In operation, the pump 9 is normally kept in operation continuously while the airport is in condition to dispense liquid fuel. When any of the delivery valves 16, 16a, etc., is open, the liquid pressure in the pipe line 13 falls and the signalled or transmitted pressure of the transmission line 22 becomes sufficiently low to cause the actua-V tor 20 to shut the main valve 12 in the by-pass line. The pump 9 is thereby enabled to force liquid fuel from the supply pipe 7 to the delivery pipe line 13 through the check valve 14, which is of the type offering a minimum of resistance. When all of the delivery valves 16, 16a, etc., are shut the pressure in the delivery pipe line rises, resulting in an increased higher signalled or transmitted pressure which causes the V'actuator 20 to open the valve 12; this decreases the pressure on the pressure discharge side of the pump, but the check valve 14 prevents back- Vilow of liquid fuel and maintains the pressure in the pipe line 13 at the increased value. The pump is thereby enabled to pump liquid through the by-pass line 11a, 11b, against a negligible pressure head. Hence it becomes unnecessary to shut down the pump 9 and the motor 10 even though a positive displacement pump, such as a reciprocating piston pump or a rotary pump, is used, and thesystem can be left ready for instant operation should one or more of the delivery valves 16, 16a, etc., be opened. It should be understood, however, that the system may also be employed with centrifugal pumps. When any of the delivery valves is opened the pressure in the delivery pipe line falls, causing the actuator to shut the valve 12 and restoring the system to the condition rst described. The usual governor on the motor 10 regulates the supply of energy to it to maintain the pump'speed more or less constant, e. g., in the case of a diesel engine, by decreasing the amount of fuel supplied when the shaft speed increases due to decreased loadV when the by-pass valve 12 is opened; hence but little power is consumed when no liquid fuel is dispensed. It is evident that such a system is well suited to use particularly at airelds where fuelling operations occur only occasionally but are yet of suicient frequency to make it inadvisable to start and stop the diesel or other engine ltles the valve 12 to varying degrees.

which operates the pump every time it is desired to fuel an aircraft.

As will be explained Vin detail below, the actuator 2l) need not be one which causes only complete opening or closing of the valve 12; it may be of the type that throt The latter is useful when, for example, several dispensing stations are provided; it then becomes desirable to shut the valve 12 completely only when liquid is being dispensed at a high rate (as when several dispensing devices are in use) Vand to shut the valve partially when liquid is being dispensed at a low rate.

The pressure reservoir 23 smooths out minor pressurefluctuations in the pipe 13. lts main function is to maintains a pressure within the delivery pipe line 13 for moderately extended periods despite a slow leakage of liquid from the pipe line, thereby preventing rapidly recurring operation of the valve 12. Rapidly recurring operation of the valve or chattering is further avoided by arranging the actuator 20 to open the valve 12 at a higher transmitted pressure than that at Vwhich the valve is closed, and such an arrangement is facilitated by the use of the reservoir 23.

The invention will be further described' with reference to a specific embodiment, which is illustrative of the diagrammatic showing of Figure l. Referring to Figure 2, the pump has the suction side 24 thereof connected to thc supply pipe 7 and to the branch 11b of the'by-passY line. The pressure discharge side 25 of the pump is connected to the branch 11a of the by-pass line and to the nonreturn valve 14, the downstream end of the latter being connected to the delivery pipe line 13 through branched conduits 26 and 27 which collectively form a part of the pressure sensing element 21 of Figure 1. The valve 14'is of a type aifording only a small resistance to the ilow of liquid in the direction of the dispensing points. The branch 26 may contain a normally-closed, spring-loaded valve 28 for diverting ow through the branch 27, thereby insuring that liquid iiow to the dispensing devices is always accompanied by liquid flow through the branch 27, even at low rates of ilow. The spring of the valve 28 is weak enough to permit the valve to be opened by the pressure of the liquid when large rates of flow occur. The branch 27 contains a venturi constriction 29 having a port 3@ connected to one end of the transmission line 22, which is in this case a bleed line and may have a small bore. The other end of the line 22 is connected to the valve acuator 29 which actuates the valve 12 in the by-pass line 11a, 11b. Connected to the delivery pipe line 13 at a point downstream of the spring-loaded valve 28 is the pressure-storage reservoir 23, which may conveniently be an air-expansion chamber, which functions to eliminate or reduce pressure uctuations which atect the operation of the actuator 20 and by-pass valve 12, such fluctuations being, for example, the effect of leakage which may occur in the delivery pipe line or in the dispensing system on shut down.

The by-pass valve 12 and actuator 20 are shown in detail in JFigure 3. They are Varranged lin a casing 31 provided with two cylindrical bores 32 and S3 of which the

plates

32a and 32b, is divided by an apertured partition 36 carrying a ring 37 which has a press t withthe partition..

averses 36;"it 'is shaped to provide -a'valve oriiceconstituting aseating for the valve member 34. The valve member 34 tion sides of the pump 9 through large por-ts' iii-'and 41,

respectively, of which port 40 is situated on the piston side of the valve member 34 and port 41 is situated on the opposite side thereof, The maximum opening of the main valve member 34 is limited by a hollow stop or projection 42formed on the end plate 32a and having a main-bore 43"and a vertical bore 43a set back from the open end thereof.' The valve member 34 is guided in its movement towards and away from the valve orice by means comprising an open cylindrical framework-44 carried by the rod 38 'and slidably engaging the cylindrical part of the orice inthe ring 37, A lowconnection is provided between that part or the chamber 32 on the inside of the piston 39` (to the right in Fig. 3) and that on-the outer face of the valve member 34, i. e., that in communication through the port 41 with the suction side 24 of the pump, to enable pressure in the space conned by the piston 39 to bleed away to suction, the' said connection comprising a n'e bore 45 extending axially through the piston 39, the piston rod 3S and the valve member 34. The eiective sizeof the bore 45 is determined by a removable, apertured plug 45 that is rotatably mounted in the main valve member 34, and can Abe adjusted to restrict the-size of thepassageway through the main valve member at will to" vary the rate at which the pressure can bleed away. Moreover, the vertical bore 43a in the stop 42 linsures that communication between the bore 45 and suction from the port 41 is maintained when the valve member 34' lies fully open against the stop 42.

The pilotvalve chamber 33 is closed at -one end by a plug 47 having a bore 48 providing Vconnection with the end of the bleed line 22;.the other end of the chamber around .which lis disposed a compression spring 57i-for biasing the pilot valve to the biased position shown. rlie end 52 of this portion 50 constitutes a stop for limiting-the movement ofthe pilot valve member 35' in the chamber 33'. The end of the pilot valve chamber 33' remote from the compression spring 51' is enlarged in two steps to form two'adjoining portions 53 and 54, the latter of which receivesfV the plug 47`and is closed thereby. he ping 47 carries a collar 55, threadedly connected for-retaining the end of the bleed line .22 which has an enlargement 55 with a frusto-conical tace for sealing contact with the plug 47. Theaxial Vbore 48'i'n the plug 47 has an enlarged portion 57iwhich` opens into the pilot valve chamber 33 and pro-- vides communication'betv/een the latter and the bleed line 221'; Slidablydisposed within, and extending the greater part of the length of, the chamber 33'is the elongated -pilotvalve member 35 comprising a central stem portionV 53 of smaller'diameterthan the bore-of the chamber 33, which stem portionis enlarged at its ends to form cylindrical portions 59'and i'which slidably engage the inner wall of the chamber 33.

The end portion 59. of the pilot valve member'35 is counterboredY and the hollow end-thereofenclo'ses part:

of the compression spring 51, whilst the other end portion` S0-'carries a shortA cylindrical extension 61 of smaller diameter. The extension 61 has a slidingY iitin the enlarged bore portion 57 and is of sufficient lengthv to remain-in sliding engagement therewith both in the-closed and partly` open positions of the valve member 35, but which is carried clear of the plug 47 at the fully open position of the' valve member.` The stem portion 58 of the valve member tapers outwardly at 62 to the' full diameter ofthe hollow end portion .S9-thereof for 'a purpose hereinafter 'explained;l

Ports 63,5 64'" and 65 are providedbetween *theV main valve chamber 32 and the pilot valve' chamber`33jof' which port 63 provides communication between the part of the chamber 33 conned between the end 59 of the pilot' valve 35 and the plug 49, and the part of the chamber 32 in the .suction side of the valve 34, and port 65 provides com# munication between the part of the control valvechamber 33 containing the central valve stem 53 and the space i on'the inner side of the piston 39; both remain open forV all positions of the pilot valve 35. Port 64, which com-v municates at one end with the pressure side of the main valve 34 and at the other end with an intermediate point of the chamber 33, is normally closed'by the enlarged en'd portion59 of the valve member and is opened progressively by movement of the valve member 35 vagainstthe spring 51.

The enlarged portion 53 of the chamber 33 is in communication with that part of the chamber 33 which'is confined between the end 59 of the pilot valve member and the plug 49 by way of a circumferential channel 66:

and radial bores 67 in the end portion 6i? and an axial bore 68 in the stern 58.

The system operates as follows:

When the shut-off valve 8 is open and liquid is owingfrom the source 'through the supply pipe 7, pump 9' and delivery pipe line 13 to the dispensing outlets 15, 15a,V etc., pilot valve member 35 is in its biased or closed posi-.- tion as shown in'Figure 3. This occurs because all-or. part of the liquid ows through the venturi constructionv 29`due to the action of the valve 255, causing suchfareduction in the pressure of the liquid in the bleed line 22 lthat the force exerted by the spring 51-overcomes the pressure exerted by that liquid on the .face A- of the.

pilot valve 35, this face being a movable wall for the.

With the pilot valve member 35 the area of the latter is greatery than that of the facev B of the valve member 34 there is a pressure diierence which holds the valve member 34 closed against its seat#- ing 37,'as shown in the drawing.

When 'the rate of liquid How to the dispensing outlets decreases as the result of closing one or more,- lessthan-l all, of the-

delivery valves

16,16@ etc., the rate ofliquidow through the venturi 2,9 decreases and the liquid pressure inthe bleed line22 Vaccordingly rises with a corre`- sponding increase in the pressure acting on the Yface VA of'fthe pilot valve member 35. As a resultv the valve member 35 overcomes the force exerted by the spring 51.'

opening of the port 64, with consequent gradual build 'up of pressure on the inner face D of the piston 39. This partial movement of the pilot valve stops when the spring 51 is compressed sufficiently to overcome the increasedV force of the huid acting on the face A. The stiffness of the spring is such that, with at least partial liquid owcontinuing through Vthe venturi constriction, the' pilot valve cornes to rest atan intermediate, partly openposition, withl the extension 61 still within the bore 57. Liquidl thus enters the right end of the chamber 32 through the' port `65 at a restricted Vrate and simultaneously bleeds oit through the bore 45. The extent to which the pressure is built up on the faceD is, therefore, dependent upon the extent to which the tapered `part 62"'uncovers the port 64.V The effect of this increase in .pressure on face D is hnally to remove thepressure difference holding' the main valve member 34 closed, whereupon the Vmain valve'opens to an extent proportional to the pressure in the' delivery line 13 'to providev an 'alternativeoutletfor" the' liquid 'discharged by the pump 9.F In Wytle" animos f 7 valve member 34 functions in a manner similar to that of the known pump relief valves.

As soon as the rate of liquid flow through the venturi 29 increases again as the result of an increased take off from the dispensing outlets, the pressure of the liquid in the bleed line 22 decreases correspondingly and the resulting reduction in the force acting on the face A of the pilot valve member 35 allows the valve 35 to move back to its rest position under the action of the spring 51. Communication between the discharge side 25 of the pump 9 and the inner side of the piston 39 through

ports

64 and 65 is thereby cut off and the pressure acting on the face D of the piston 39 decreases by bleeding to suction through the bore 45 in the piston rod 3S; the valve 34 therefore closes again as soon as the pressure difference on the adjacent sides of the valve member 34 and the piston 39 due to the difference in their surface areas is re-established.

When all the delivery valves 16, 16a, etc., of the dispensing system are shut down, liquid ow through the venturi 29 ceases and the pressure in the bleed line 22 increases to such an extent that the pilot valve 35 moves suiciently to cause the extension 61 to leave the bore 57 of the plug 47. As soon as this occurs the pressure in Vthe bleed line 22 operates over a larger area comprising the area of the face A at the end 61 and the area of the annular face E at the end of the enlarged end 6G, with the result that the pilot valve continues its movement against spring 51 to uncover the whole area of the port 64, thereby admitting liquid far in excess of the rate of bleed through the bore 45 and applying maximum pressure against the face D of the piston 39. The valve 34 then opens fully and the non-return valve i4 closes with the result that the valve 12 provides a low-resistance bypass through which liquid can be circulated by the pump 9 at a low pressure and with little expenditure of energyv by the engine driving the pump.

When liquid ow to a dispensing station recommences, the pressure in the bleed line 22 decreases and the pilot valve 35Y moves to the right under the action of the spring 51. However, since in the extreme open position of the pilot valve 35, the pressure of the liquid in the bleed line 22 acts on the whole of the area of the faces A and E (on the portions 6i and 69 of the member), the pilot valve 35 will move to the closed position only when the bleed line pressure falls to a value, for example 15%, below that causing initial opening of the pilot valve 35. This has the etfect of compensating to a certain extent any pressure drop due to leakage in the delivery line 13 or the dispensing system, thereby avoiding chattering kor sudden reciprocatic-ns of the pilot valve.

During closure of the pilot valve liquid trapped in the enlarged portion 53. of the chamber 33 by the re-entry of the extension 61 of the valve member into the bore 57 ilows t'o suction via the bore 68 in the valve Vmember and the port 63, and the port 64 becomes progressively obturated by the valve member 35, thereby correspondingly reducing the pressure acting on the face D of the piston 39 which results in partial or complete closure of the valve member 3a.

The pressure storage vessel 23, which is an optional component, also functions Vto retain in the delivery line 13 the pressure required to maintain the pilot valve 35 open in spite of any moderately small leakage that may occur in the delivery line 13 or inthe dispensing system itself over the period during which the delivery valves are shut. The pressure storage vessel 23 also acts as a shock absorber and may thus replace any shock pressure absorber which might otherwise be needed.

It will be apparent from the foregoing description that the present invention comprises Va liquid dispensing system which includes means operative automatically in response to pressure variations in the delivery line to provide the usual by-pass facility on partial Vshut-down of the dispensing system and in addition to provide a lowresistance by-pass for the pump on complete shut-down thereof, without the need for any control of the pump by the operator at the dispensing stations. Y

While the fluid in the transmission or bleed line 22 is, in the embodiments shown, the same as that owing through the delivery pipe line, it should be understood that the invention is not limited thereto, and that the fluid acting on the movable wall A of the pilot valve may be a different liquid which may, if desired, be isolated from the liquid in the pipe line through any suitable means, such as a diaphragm or pistons,

i ciaim as my invention: v

l. A liquid-dispensing System including: a pump having suction and discharge sides; a delivery pipe line connected to the discharge side 'of said pump; at least one dispensing device including a delivery valve connected to said delivery pipe line; a non-return valve in said delivery pipe line, said non-return valve being disposed to permit liquid ow from said pump to the ldispensing des vice but not vice versa; a by-pass line providing a low- Vresistance ow path for liquid between the discharge and suction sides of said pump; a by-pass valve in said bypass line which is operative to vary the resistance to liquid' flow through said by-pass line; and a pressure-responsive valve actuator for said by-pass valve connected to respond to the pressure in said delivery pipe line at a point therein located between said non-return valve and the said delivery valve, said actuator being disposed to actuate the by-pass valve to decrease the said resistance to ow through the by-pass line when the pressure at said point kin the delivery pipe line rises to a predetermined value.

2. A liquid-dispensing system as set forth in claim 1 wherein said valve actuator is arranged to increase Vthe said resistance to flow through the by-pass line only when the pressure at said point in the delivery pipe line falls to a second predetermined value Which is lower than said between said non-return valve and the said delivery valve;

a by-pass line providing a low-resistance flow path for liquid between the discharge and suction sides of said pump; a by-pass valve in said by-pass line which is operative to vary the resistance to liquid flow through said bypass line; and a pressure-responsive valve actuator for said by-pass valve connected to respond to the pressure in said delivery pipe line at a point therein located between said non-return valve and the said delivery valve, said actuator being disposed to actuate the by-pass valve to decrease the said resistance to ow through the by-pass` line when the pressure at said point in the delivery pipe line rises to a predetermined value.

4. A liquid-dispensing system including: a pump having suction and discharge sides; a delivery pipe line connected to the discharge side of said pump; at least one dispensing device including a delivery valve connected to said delivery pipe line; a by-pass line providing a low-resistanceV ilow path for liquid between the discharge and suction sides of said pump; a by-pass valve in said by-pass line including a main valve member movable to progressively di'erent positions to vary the said resistance to liquid flow in gradations to values dependent upon the positionV of the valve member; a pressure-responsive valve actuator l for said by-pass valve including at least one movable wall operatively connected to said main valve member for movement therewith and exposed to fluid pressure, a pilot valve having a pilot valve member movable to progressively different positions and Varranged lto control in gradations the admission of uid to act on swamps#- said'movable-wall in accordance'with the position 'of the pilotvalve member, said pilot valve havingbiasing means for-biasing the pilot valve member to a biased'position anda second movable wall operatively connected to said pilot'valve member for moving the pilot valve member progressively away from said biased position' `upon the application of increasing fluid pressure against said second movable wall; and a uid pressure transmission line Vhaving one end thereof connected to the pilot valve for admittinga uid against said second movable wall and the other end thereof connected vto means for supplying fluid thereto at a pressure that Vdepends upon the pressure in said delivery pipe line, said rst-mentioned movable wall being so exposed to uid pressure as to'move said mainY valve member toward open position upon a rise in the said* pressure in the delivery pipe line.

5. A liquid-dispensing system as set forth in claim 4, wherein the said means for supplying uid to the fluid transmission line includes means responsive both to the rate of liquid ow through said delivery pipe line and to the static pressure therein, an increase in said static pressure acting in the same sense as a decrease in said rate of liquidfiow;

6. A liquid-dispensing system as set forth in claim 5, wherein the relation of the area of said second movable wall and the said biasing means is such that said main valve is moved to fully open position only upon substantially total cessation of ow in thesaid delivery pipe line.

7. A liquid-dispensingY system las setY forth in claim 4, whereinsaid delivery pipe line has a non-return valve therein disposed to permit 'liquid flow from said pump to the dispensing device but not vice versa, and said means for supplying uid to the uid pressure transmission line is connected to a point in the delivery pipe line between said non-return valve and the said delivery valve and is disposed to supply uid at a pressure determined by the pressure at said point in the delivery pipe line.

8. A liquid-dispensing system as set forth in claim 7, wherein the said means for supplying uid to the uid transmission line includes a venturi constriction in said delivery pipe line and a port in said venturi constriction connected to said transmission line, whereby the pressure in said transmission line becomes greater in response to an increase in the said static pressure and also in response to a decrease in said rate of liquid ow.

9. A liquid-dispensing system as set forth in claim 8, wherein the said liquid delivery pipe has at least two parallel branches at said point therein interconnected both at their upstream and downstream ends, said venturi constriction being situated in the first of said branches and all the other of said branches containing dow-restrictive means for diverting ow through the first said branch during low liquid flow rates, whereby at least some ow of liquid occurs through said venturi constriction whenever any liquid flows through said delivery pipe line.

10. A liquid-dispensing system including: a pump having suction and discharge sides; a delivery pipe line connected to the discharge side of said pump; at least one dispensing device including a delivery Valve connected to said delivery pipe line; a non-return valve in said delivery pipe line, said non-return valve being disposed to permit liquid ow from said pump to the dispensing device but not vice versa; a by-pass line providing a path having low-resistance to liquid flow from the discharge side to the suction side of said pump; a by-pass valve in said by-pass line including a main valve member movable to different positions to control the said resistance to liquid flow to values dependent upon the position of the valve member; a pressure-responsive actuator for said by-pass valve including at least one movable wall operatively connected to said main valve member for movement therewith and exposed to uid pressure, a pilot valve having a pilot valve member movable to different positions and arranged to control the admission of fluid to act on said movable wall in accordance with the position of the pilot valve member,

said plotvalve having biasing means-'for biasingthe pilot valve member to a biased'position at which the admission of Vtluid is controlled so as tomove saidmain Valve member to impose a high resistance to flow'of liquid in the bypass line and a second movable Wall operatively connected to said pilotl valve member for moving the pilot valveA member away from said biased position upon theappli-v cation of increasing fluid pressure against-said second' movable wall; and a uid pressure transmission-line-hav-v ingone end thereof connected to the pilot valve to supply uld under pressure to act on said second movable wall and the other end thereof connectedV to a point in the liquid delivery pipe line between said non-return valve andthe" said deliveryvalve to receive uid at a pressure that rises with increasing pressure in said delivery pipe line.

ll. A liquid-dispensing system including: a pump having a suction side connected to a liquid supply source and a discharge side; a delivery pipe line connectedto the discharge side of said pump; at least one dispensing device including a delivery valve connected lto said delivery pipe line; a non-return valve in said delivery pipe line, said non-return valve being disposed to permit liquid ow from said pump to the dispensing device but not vice versa;-a by-pass line providing a low-resistance'pathA for liquid flow -betweenthe discharge and suction sides of said pump; a by-pass valve in said by-pass line which is operative vtovarythe resistance toliquid lowv through said bypass line; a tuid .pressure-responsive valve actuator for said 'oy-pass valve disposed to actuate the by-pass valve to decrease the said resistance to llow through the by-pass line when .the fluid pressure acting on they actuator `in'- creases and to actuate the by-pass valve to increase the said resistance upon a decrease inthe said iluid pressure;A

and a uid transmission line having one end thereof connected to said valve actuator to admit said uid at a variable pressure so as to act on said actuator and having the other end thereof connected to said delivery pipe line at a point therein located between said non-return valve and said delivery valve in pressure-transmitting relation so as to subject uid in the transmission line to a pressure that increases as the pressure in the delivery pipe line increases.

12. A liquid-dispensing system as set forth in claim l1, wherein the said delivery pipe line includes a venturi constriction at the said point therein, in said venturi constriction having a port and the transmission line being connected to the delivery pipe line through said port, the said valve actuator being arranged to move the by-pass valve to fully open position only upon a rise in the pressure in the transmission line to a predetermined value corresponding to a condition of substantially zero flow of liquid through the venturi constriction.

13. A liquid-dispensing system as set forth in claim 12, wherein said valve actuator is arranged to move the bypass valve from its fully open position only when the uid pressure in the transmission line falls to a second predetermined value which is lower than said inst-mentioned predetermined value.

l4. A liquid-dispensing system as set forth in claim 13 and including a pressure storage vessel communicating with said delivery pipe line at a point therein between said non-return valve and the said dispensing device.

l5. A liquid-dispensing device as set forth in claim ll, wherein the said by-pass valve and valve actuator include: a casing having a ported partition dividing the casing into a high-pressure chamber and a low-pressure chamber connected by said by-pass line respectively to the discharge side and to the suction side of said pump, said casing having further a cylindrical chamber in open communication with the high-pressure chamber; a main valve member reciprovably mounted within said casing and having a seating against said partition for closing the port therein, the area of said cylindrical chamber being greater than the area of said valve member; a piston in said cylindrical chamber connected to said valve member, whereby pressure in said high-pressure chamber acts ammesse with a relatively larger force on said piston urgingthe valve member to seat on the partition, and with a relatively smaller'rforce on said valve member urging the valve member away from the partition; a passageway interconnecting the said high-pressure chamber and the end part of the cylindrical chamber on the side of the piston remote from the high-pressure chamber; a pilot valve for regulating the flow of liquid through said passageway; and outletrneans for the discharge of liquid from said end part of the cylindrical chamber.

16. A liquid-dispensing device as set Vforth in claim l5, wherein said outlet means for the cylindrical chamber includes a restricted duct for bleeding into said low-pressure chamber.

17. A liquid-dispensing device as set forth in claim l5, wherein said pilot valve has a graduated passageway for regulating said flow of liquid through the passageway in gradations in accordance with the position of the pilot valve.

18. A valve actuator comprising a casing providing a Huid pressure chamber, said chamber containing therein at least one movable wall adapted for operative connection to a valve member to be actuated; a pilot valve having a pilot valve member movable to progressively different positions and arranged to control in gradations the admission of iluid to act on said movable wall in accordance with the position of the pilot valve member, said pilot valve having biasing means for biasing the pilot valve member to a biased position and a second movable wall operatively connected to said pilot valve member for moving the pilot valve member progressively away from said biased position upon the application of increasing uid pressure against said second movable wall;'and an inlet to said casing for admittinga pressure iiuid against said second movable wall.

19; A valve-and a valve actuator therefor comprising: a casing'having a ported ypartition dividing thercasing into a high-pressure chamber and a low-pressure chamber; openings'in said casing cormnunicating with said chambers for connecting feed and discharge pipes to the high-pressure and low-pressure chambers, respectively,V

urging valve member totseat on the partition, and with a relatively smaller force on said valve member'urging the valve member away from the partition; a passageway interconnecting the said high-pressure chamber and the end part of the cylindrical chamber on the side of the piston remote from the high-pressure chamber; a pilotV valve forV regulating the ow of liquid through said passageway; and outletmeans for the discharge of liquid from said end part of the cylinder.

References Cited in the ile of this patent UNITED STATES PATENTS 1,978,597 Peter oct. 30, 1934 2,138,755 Beesten Nov. 29, 1938 2,330,703 Grise sept. 28, 1943

Claims

1. A LIQUID-DISPENSING SYSTEM INCLUDING: A PUMP HAVING SUCTION AND DISCHARGE SIDES; A DELIVERY PIPE LINE CONNECTED TO THE DISCHARGE SIDE OF SAID PUMP; AT LEAST ONE DISPENSING DEVICE INCLUDING A DELIVERY VALVE CONNECTED TO SAID DELIVERY PIPE LINE; A NON-RETURN VALVE IN SAID DELIVERY PIPE LINE, SAID NON-RETURN VALVE BEING DISPOSED TO PERMIT LIQUID FLOW FROM SAID PUMP TO THE DISPENSING DEVICE BUT NOT VICE VERSA; A BY-PASS LINE PROVIDING A LOWRESISTANCE FLOW PATH FOR LIQUID BETWEEN THE DISCHARGE AND SUCTION SIDES OF SAID PUMP; A BY-PASS VALVE IN SAID BYPASS LINE WHICH IS OPERATIVE TO VARY THE RESISTANCE TO LIQUID FLOW THROUGH SAID BY-PASS LINE; AND A PRESSURE-RESPONSIVE VALVE ACTUATOR FOR SAID BY-PASS VALVE CONNECTED TO RESPOND TO THE PRESSURE IN SAID DELIVERY PIPE LINE AT A POINT THEREIN LOCATED BETWEEN SAID NON-RETURN VALVE AND THE SAID DELIVERY VALVE, SAID ACTUATOR BEING DISPOSED TO ACTUATE THE BY-PASS VALVE TO DECREASE THE SAID RESISTANCE TO FLOW THROUGH THE BY-PASS LINE WHEN THE PRESSURE AT SAID POINT IN THE DELIVERY PIPE LINE RISES TO A PREDETERMINED VALUE.