US2478410A - Fluid pressure operated pump - Google Patents

Description

Aug. 9, 1949. F. M. M DOUGALL FLUID PRESSURE OPERATED PUMP Filed July 22, 1944 5 BY [@7M @71 Patented Aug. 9, 1949 umT-Eo ermine r-Applicationiluly 22, 1944,.s'eria1m. M13123" (o1; ms--46-) 1701MB; i.

"This invention relates to pum s, and marshesticu'larly to a pump which is operated "by fluid pressure from aremote source.

An object is to produce an improved fliiidlpressure operated pump which will have its plunger positively moved in opposite directions by fluid pressure transmitted thereto from a remote source through a single conduit.

Another object of the invention is t :pro'd'uce an improved jpmnpiin which therpumpingsplunger is caused to be reciproca'ted by changes in fluid pressure .developedat a remote point.

A .f-unther object ,is to associate withapump operated by fluid pressure-tram a rremoteasoume an improved pressure-operated valve for nontrolling the alternate anplioation of the fluid pressure to iopposite sides of a member eonnected lto :reciproeatera pump plunger.

Other obj sets of the invention will become :apparent- :from the following description taken in connection with the accompanying drawing showing the invention embodied :in 1a deep-well pump as bywaw-of-example.

In-the dra-twings:

Fig. is a schematic mew partly in section of a deep-well pumping. system showing both the surface meohanism sand the sub-surface pump mechanism;

Fig. 2 :is an enlargedusectional wiew nf-thezsum :surfiace pumpmiechamism; "and Fig.3 isenlarged sectional view oif rthefluid ;pnessure developing :pistma and cylinderremblnation forming a mart of the mechanism.

Referring 110213116 drawlngs detail thelpumping system shown as being employedwaswiieep 'weH pump comprises sa-gpump'iunit I 0 mositioned Eat the :bottom' of the well casing in and armressure-generatihg means M situated zonlthe- 51.11 :taee of the earth. The wellcasmg extending" from fihessur-face zhaspositionredthereimagproduo- :tion tube or pipe 43' extends immune em- :faoe'to the bottom df time-easing. Atzthetsuriace, (the tube 1:3 li's suppm ted robnneuted lwith'iihe easing by a normectnr' M. flhere'zis also provi'ded4a' cap .15 for sealing e'ofi theetnpwof the time. From snap a pipe 1'5 menus tore receiver tor tank all! .liqnidnt iahelhdt- "tomnf tine' well is to be pumped.

pump 1H] rcompnises a head member 18 which has depending therefrom a mylllnder 18 provided with an end wall 20 having 1a 4301111021 surfaoe which-rests ina cionicali-reoess as-olosure plug -2I for thelower end-.Qfthe tube L3. olosure plug 21I names .a-gaerfomated cylindrical extensionI'Zlextendingihto the liquid zone tension is of sma'ner diameter'than "the'p'lurrger 21' in order that the areas onthe oppositesldes or.rhep-ist nrewiirbemrferent. estimableeek- 'ing 31 sealstlfis extension the" end wall permits re iprocation of "the extension through me-end well; .An' axiarpassage-M extends"oom'- plet'ely through the plunger! T, pistonfzfl, ta'nd extension 29 andlserves'asan inlet to 11ermit'=1ig:- did at 'iihe bottom 0'f"th'e We'll :fibwifitd the chamber 26 ahead of theplunger; The passage is cbhtrolled"b37 a 'haIl-he'ck Valve '33 Wh'ifih prevents liquid'ffi'orn flowing" out .or "the chamber-rs after it haswonc'e entered said chamber; The chamber 26 also has 'ar'ns uppe'rie'nd an outlet ,port M with which-is associated 1a s'eoo'nd"b'a'll"- eheok- -Valve arranged to prevent" from re-enter'ing th'e .c'hambe'r '25" afte'rii-t' has onceTbeeh discharged therefrom through the outlet ,port. The passagel36 conneo't's the outletjporlt 3}" with the production tube 13 whereby the discharged liquid from the pump ehaniber' 2B canbe received in the tube and then-lforeedoutof the-stop of'ltlfis tube into the pipe Zlliandihe receiver.

'Thehead member I3 is arranged to he connested by a pipe 371 to the ipressmegenerafiing means l2 on ,the surf'aee. Gommunioatingo with this "pipe iswaspassage 3} in the head nembe'r and in the member which passage leads to the chamber 39 withln the loyilinder-flandaloove the piston 23". The head member is also provided with a v branohapassage 3B which-places theepipe .3?! in teommunioation with .the top -end =-ofa bore min the member. this hore-isea-shooltype valve ielementdl oomprisingspaced cylindrioalheads 42 and 43 and a rteduced eonhecfing part 44 providing an annular groove 45 between the heads.

The spool valive' element isarranged \to'ioontrol :communication between =a'-;passage 46' and passages 41' and-48 Passage 4B- is-arranged J10 3 connect the interior of the production tube l3 with the bore 49. Passage 41 is arranged to connect the passage 38 with the interior of the bore 49. Passage 46 connects the bore 40 with the interior of the cylinder l9 which, at its lower end, is in constant communication with chamber 49 at the lower side of the piston 28. The passage 46 enters the bore intermediate the passages 49 and 41 and is arranged so that the ends of the spooltype valve element do not affect its communication with the annular groove in the element. The valve element is normally biased to the position shown in Fig. 2 where the passage 48 can communicate with the passage 46, said biasing means comprising a coil spring 50 of predetermined strength. When the valve element is in such position, the passage 4'! will be cut off from the passage 46 by the cylindrical portion 43 of the valve element. If the valve element should be moved downwardly its permissible extent against the bias of the spring 50, it will assume a second position where the cylindrical end 42 will cut off the passage. 48 and the cylindrical end 43 will open up the passage 4'! for communication with the passage 46.

The pipe 31 which extends from the head member I8 of the pump is connected by branch conduits to opposite ends of a cylinder in which is reciprocable a piston 52 having a piston rod 53 connected .to a second piston 54 reciprocable in a second cylinder 55. The cylinder 5| is closed at both ends and the piston rod 53 within the cylinder is of predetermined diameter in order that the piston and cylinder can produce predetermined different displacements when operated in different directions. This is apparent since the area of the piston 52 which acts on theliquid at the rear of the piston will be smaller than the area of the head of the piston which acts on the liquid. The branch conduit 31 which connects the forward end of the cylinder 5| to the pipe 31 is provided with a check valve 56 for preventing liquid from entering the cylinder when pressure is being developed by a rearward movement of the piston. cylinder 5| is connected ,by the pipe 51 to the receiver IT in order to be supplied with liquid. Associated with this conduit is a filter 58 and a check valve 59.

r The piston 54 may be reciprocated within the cylinder 55 by any suitable medium, which may be compressed liquid or compressed air. The medium employed in the particular system shown is a liquid which is placed under pressure by a hydraulic pump 6|] driven by prime mover 6|. The pump 50 is arranged to alternately deliver liquid under pressure to the opposite sides of the piston 54, and this is accomplished by suitable piping with which is associated a reversing valve 62. This valve is controlled by an oscillating fork 63 actuated by a projection 64 on a rod 65. The rod is carried by arms 66 and 61 pivoted intermediate their ends to a bar 68. A lug 69 on the piston rod 53 is arranged toengage the arms and cause the rod 65 to be moved back and forth to bring about the proper control of the reversing valve. The valve will be reversed at the end of each stroke of the piston 54 so as to cause the piston 54 to be moved in the opposite direction.

Operation Referring to the operation of this pumping system, the relative sizes of the plunger 21 and the extension 29 have a definite relationship to The forward end of the each other and the displacement effected by the reciprocation of the piston 52 in the cylinder 5|. The chamber 39 above piston 28 will be the only chamber connected to the cylinder 5| during the forward stroke of the piston 52, and the arrangement is such that the volume of fluid displaced into the chamber .39 by the piston 52 during its forward stroke will be sufficient to fill the chamber 39 when the piston 28 is at its lower end as shown in Fig. 2. In connection with the volume of fluid displaced into chamber 39 by the piston 52 during its forward stroke, it is to be noted that such is the volume actually displaced by the piston minus'the volume at the rear of the piston since, during this stroke of the piston, liquid is free to bypass into the cylinder at the rear of the piston. During the rearward stroke of the piston 52 the volume of fluid displaced will be equal to the volume of chamber 49 when the piston 28 is at the upper end of its stroke minus the volume of chamber 39 when the piston 28 is at the lower end of its stroke. This is apparent since the valve 4| will be positioned to interconnect both chambers 39 and 49 and the volume to be made up need only be the difference between the chambers.

When the-piston 28 and the plunger of the pump are at the positions shown in Fig. 2, the piston 52 will have just completed its forward stroke and be in the position shown in Fig. 3. The valve element will still be in its upper position as shown as the pressure developed during movement of piston 52 is insuflicient to overcome the-bias of the spring 59. When the piston 52 begins to move rearwardly a high fluid pressure will immediately be created since the piston 28 is no longer free to move downwardly. This pressure will result in the valve elements being moved downwardly so as to cut off the passage 48 and place the chamber 39 in communication with the chamber 49 through the passage 41. The pressure being developed by the piston 52 will now be effective in both chambers 39 and 49, but since a larger area of the piston 28 is exposed to the fluid pressure in chamber 49 than the area exposed to the same pressure in the chamber 39, the piston will be caused to move upwardly thereby moving the plunger 2'! upwardly. Since liquid to be pumped has already filled the chamber 26 ahead of the plunger, the upward movement of the plunger will result in the ball valve 33 being held closed and liquid discharged through the port 34 and passage 36 into the production tube I3 where it will be forced upwardly and then through the pipe IE to the receiver.

When the piston 23 and'the plunger 2'! have reached their upward extent of travel, the piston 52 in cylinder 5| will have reached the end of its rearward stroke; and at such time the reversing valve 62 will be operated and the piston 52 again moved forwardly. At the time that the reversal of movement of the piston 52 takes place, there will be a drop of liquid pressure and consequently the spring 59 will become effective to move the valve element 4| upwardly to the position shown in Fig. 2 where it will be maintained. As the piston 52 moves forwardly, the pressure being developed will be of such value as to permit the spring of predetermined strength to maintain the valve element in its upper position. With the valve element in such upper position, the

passage-4'! will be cut off and the passage 48 connected to the passage 46. This position of the valve will result in the chamber 49 below the piston 28 being connected with the production tube so that the liquid in said chamber It can be pushed into the production tube as the piston moves downwardly, the downward movement 'of the piston 28 being brought about by the fluid pressure being developed by the forward movement of the piston 52. The downward movement of piston 28 carries with it the plunger 21, and a new charge of liquid to :be pumped will enter the chamber by the unseating of the inlet ball valve When piston 52 again reaches its'fonward position as shown in Fig. 3, the volume of fluid displaced will have been sufficient to move the piston 28 to the position shown in Fig. 2, and the suction stroke will be completed. As the piston 52 again moves rearwardly, the valve element 4i will again be acted upon by the higher fluid pressure developed by the piston to again assume its lower position so that both chambers 39 and it will be subject to the developed fluid pressure to bring about me upward movement of the plunger ill in the manner already described.

if it should be desired to change the stroke of the pump plunger this can be done by changing the stroke of the piston 52. With a shorter stroke of the piston 52, 1e volume displaced by the rearward movement of this piston will be less, and, consequently, the piston 28 will be moved through only part of its available stroke, thus giving a similar partial stroke to the plunger 2?. When the piston 52 reverses its movement from a rearward movement to a forward movement, the valve ll will again be permitted to assume the position in Fig. 2 thus resulting in the piston 52 during its forward stroke returning the pump plunger to the position shown in Fig. '2.

It is obvious that the operation will be unchanged by using two cylinders with singleacting pistons in place of the double-acting pressure-generating piston l'slprovided the respective piston areas and piping arrangement are com parable. It is not necessary in order to have the pump operated to provide single-acting pressuregeneratii pi ns oi different areas. Where the two pressure-generating pistons have equal areas and disp c cuts, the area on the lower side of piston 2. es the of the upper side. The cylinders wn e supplied with parallel supply lines and check valves tiiyand they will be connected in parallel to the discharge line through separate check valves 55. The pistons will be alter: tely operable to displace fluid. During the suction stroke of the pump plunger H, the rate of displace: ut of the surface piston will be lin to p ent the pressure rising sufficiently to move the valve element ll against the spring 5%.

Being aware of the possibilities of modifications inthe structure disclosed without departing from the fund. .ental principles of this invention, it is not intended. that its scope be limited except as set forth in the appended claims.

What is claimed is:

1. In a pump mechanism for operation by a source of pressure situated at a remote point, a pump having a chamber and a "eciprocable plunger ti "or, valve-controlled inlet means to the cha-.-ber from a body of liquid to :be pumped, a valve-controlled outlet means from the chamber for discharging liquid, a doubleacting fluid motor having a movable member connected to the plunger, said member having opposed surfaces of different areas, and fluid pressure-operated valve means controlled by fluid pressure from the source and having .an element movable in response to pressure condi- 6 tions at said source, to one position for connect ing' the source to apply fluidpressure to one area of the member andmovable in response to different pressure conditions at the source to another 1 position for connecting the source to apply fluid pressure to both areas and simultaneously permit the interchange of fluid from one side of the member to the other side.

2 In a pump mechanism for operation by a I source or pressure situated at a remote point and having periodic fluctuatings in pressure, a pump having a reciprocable plunger, a double-acting fluid motor having a movable member connected to move the plunger, said member having opposed surfaces oi different areas the larger of which is to be acted on by fluid pressure from the source to move the plunger in a pumping direction, conduit means for connecting the chambers on both sides of the member to the source and the chamber on the side of the larger area with a discharge port, and valve means for cutting oil" the chamber on the side of the larger area from the source and placing it in communication with the discharge port, and means controlled by the fluid pressures from the source for controlling the valve means, comprising 'a pressure. chamber to receive pressure from the source to displace ac valve, and means applying a predetermined opposing force against the pressure of the charm her to predetermine the pressure at which the valve means moves.

3. In a pump mechanism for operation by a source of variable fluid pressure situated at a remote point, a chamber for receiving liquid to be pumped, a second chamber having an inlet port for receiving fluid from the first chamber and an outlet port for discharging fluid, passage means for conducting liquid from the discharge outlet port, valve means associated with the inlet and outlet ports, a plunger in the second chai. her, a fluid motor connected to operate the plunger and having a movable member provided with opposed areas of diilerent sizes, conduit means for connecting the source of fluid pressure to the opposite side of the movable member of the motor, and means comprising a valve element having one position for connecting the source to the motor on the side of its movable member having the smaller area and for connecting the motor on the side of its movable member having the larger area with the passage means and a second position for connecting the source to the motor on both sides of the movable member and for disconnecting the passage means with the motor, and means responsive to variations in fluid pressure from the source for maintaining the valve element in the second position by a lower fluid pressure for permitting the valve element to be in the first position.

4. In a pump mechanism for operation by a source of pressure situated at a remote point and having periodic fluctuations in pressure, a pump having a reciprocable plunger, a doubleacting fluid motor having a, movable member connected to the plunger, said member having opposed surfaces of different areas arranged so that when both areas are subject to the same fluid pressure a diiierential force will be present to move the plunger in a pumping direction and when the smaller area is subject to a pressure the plunger will be retracted, and a single valve provided with a spring-biased element having one position for placing the chamber of the fluid motor on both sides of the member in communication with each other and the source and another position for placing the chamber of the fluid motor on the side of the member having the smaller area in communication with the source and the chamber on the other side in communication with a discharge port, said valve element being controlled by fluid pressure from the source and caused to be held in the first position against the bias of the spring by fluid pressure from the source and permitted to assume the second position by spring action as a result of decrease in the pressure from the source.

5. In a deep-well pump for operation by a remote source of fluid pressure, the combination with a production tube, a pump within the tube and comprising a chamber and a plunger reciprocable therein, means for separating the tube 'from the body of liquid to be pumped from the bottom of the well, a cylinder below the chamber, a piston in the cylinder and connected on one side to the plunger, an extension on the other side of the piston extending into the body of liquid to be pumped, said plunger and extension being of such size as to provide a smaller area on the plunger side of the piston, said plunger, piston and extension being provided with an inlet passage for the pump chamber, a check valve for the inlet passage, means providing an outlet passage from the pump chamber to the production tube, a check valve for the outlet passage, conduit means connecting the source with the cylinder on both sides of the piston and the larger area piston side with the production tube, a single valve for controlling the conduit means and having a spring-biased valve element which in one position places both sides of the piston in communication with the source and with each other and in another position disconnects the larger area side from the source and connects it with the production tube, and means for controlling the positioning of the valve element by different pressures from the source.

6. In combination, pump mechanism comprising a source of pressure including a cylinder and reciprocating piston, means for reciprocating the piston, and means for varying the stroke of said piston, a pump unit situated at a remote point from said source of pressure, conduit means connecting said source of pressure and said pump unit, said pump unit including a chamber and a reciprocable plunger therein, a valve-controlled inlet means to the chamber from a body of liquid to be pumped, a valve-controlled outlet means from the chamber for discharging liquid, and means comprising a double-acting fluid motor and valve means controlled'by fluid pressure from said pressure source for causing the plunger to be reciprocated by pressure from said fluid source, the total length of reciprocable travel of said plunger being dependent upon the stroke of said piston of the said pressure source, whereby there obtains a pumping mechanism which may be operated at a partial reciprocal movement of the pump unit plunger or at a full reciprocal movement thereof.

7. In combination, pump mechanism comprising a source of pressure including a cylinder and reciprocating piston, means for reciprocating the piston, and means for varying the stroke of said piston, a pump unit situated at a remote point from said source of pressure, conduit means connecting said source of pressure and said pump unit, said pump unit including a chamber and a reciprocable plunger therein, means for introducing a liquid into and for exiting a liquid from said chamber, and means comprising a double-acting fluid motor and valve means controlled by fluid pressure from said pressure source for causing the plunger to be reciprocated by pressure from said fluid source, the total length of reciprocable travel of said plunger being dependent upon the stroke of said piston of the said pressure source, whereby there obtains a pumping mechanism which may be operated at a partial reciprocal movement of the pump unit plunger or at a full reciprocal movement thereof.

8. In combination, a pump mechanism adapted for deep well use including a surface unit and a subsurface unit, conduit means connecting said units, said surface unit including a cylinder and reciprocating piston therein, said conduit being operatively connected into said cylinder, means for reciprocating said piston, means to adjust the length of the stroke of said piston, and means for introducing a source of oil into said cylinder for m'ovement under pressure into said conduit, said subsurface unit including a pump having a chamber, a reciprocable plunger therefor, means for introducing a liquid being pumped into said chamber and for exiting it therefrom, a doubleacting fluid motor for reciprocating said plunger, liquid passages for liquid under pressure leading to both sides of said motor, and valve means controlling flow of pressure liquid to the lift side of said motor, said valve means being controlled by the pressures set up by the piston in said pressure liquid, said motor and therethrough said plunger being moved a distance on the lift stroke dependent upon the stroke of said piston whereby a partial or full stroke of the plunger obtains as desired.

9. In combination, a pump mechanism adapted for deep well use including a surface unit and a subsurface unit, conduit means connecting said units, said surface unit including a cylinder and reciprocating piston therein, said conduit being operatively connected into said cylinder, means for reciprocating said piston, means to adjust the length of the stroke of said piston, and means for introducing a source of oil into said cylinder for movement under pressure into said conduit, said subsurface unit including a pump having a chamber, a reciprocable plunger therefor, means for introducing a liquid being pumped into said chamber and for exiting it therefrom, a double-acting fluid motor for reciprocating said plunger, liquid passages leading from the conduit to the lift side of said motor, between the lift side and the other side of said motor, and from the lift side to exhaust therefrom, valve means controlling liquid flow in said passages, liquid passages from said conduit to said other side of said motor at all times effective to supply liquid under pressure to said other side of said motor, said valve means being controlled by the pressures set up by the piston in said pressure liquid, said motor and therethrough said plunger being moved a distance on the lift stroke dependent upon the stroke of said piston whereby a partial or full stroke of the plunger obtains as desired.

10. In combination, a pump mechanism including a pump unit, a remotely disposed pressure source, and conduit means connecting said unit and pressure source, said pressure source including a cylinder and adjustable stroke piston therein, said pump unit including a chamber for receiving liquid to be pumped, a reciprocable plunger in said chamber, means for introducing a liquid into and exiting it from said chamber, a two-way fluid motor operatively associated with said plunger for reciprocating the same, and means for applying pressure from said pressure source to: said motor toelfect reciprocation thereof including liquid passages and a valve controlling certain" of. said passages, the length ofxthe pumping stroke of. said motor depending upon the length of the stroke of said piston of the pressure source, saidpumping strokeof the motor being variable through adjustment of the stroke of said piston,

11. In combination, a pump mechanism including a pump unit, a remotely disposed pressure source, and conduit means connecting said unit and pressure source, said pressure source including acylinder and adjustable stroke piston therein; said pump unit including a chamber for receiving liquid to be pumped, a reciprocable plunger in said chamber, means for introducing a liquid into and exiting it from said chamber, a two-way fluid motor opcratively associated with said plunger for reciprocating the same, and

means for applying pressure from said pressure source to said motor to effect reciprocation there of including liquid passages leading from the conduit to the lift side of said motor, between the lift side and the other side of said motor, and 3 from the lift side to exhaust therefrom, a single valve controlling liquid flow in said passages, liquid passages from said conduit to said other side of said motor at all times effective to supply liquid under pressure to said other side of said motor, the length of the pumping stroke of said motor depending upon the length of the stroke of said piston of the pressure source, said pumping stroke of the motor being variable through adjustment of the stroke of said piston.

12. In a pump, a housing, cylinder means therein, piston means in the cylinder means having opposed operating faces of different areas, a high pressure port in the housing connected to the cylinder means to apply fluid under pressure to the smaller face, passage means to connect said high pressure port to the cylinder means to apply pressure to the larger face, valve means controlling said passage means, yieldable force means acting on said valve means to cause it to maintain the passage means closed, a pressure chamber to receive fluid pressure from said high pressure port, to cause the valve to move against the force means and open the passage means when the fluid pressure in the high pressure port attains a predetermined pressure value, and pumping means having a movable member connected to the piston means to be operated by movement thereof.

13. In a pump, a housing, cylinder means therein, piston means in the cylinder means having opposed. operating faces of different areas, a high pressure port in the housing ccnnected to the cylinder means to apply fluid under pressure to the smaller face, passage means to connect said high pressure port to the cylinder means to apply pressure to the larger face, valve means controlling said passage means, yieldable force means acting on said valve means to cause it to maintain the passage means closed, a pressure chamber to receive fluid pressure from said high pressure port, to cause the valve to move against the force means and open the passage means when the fluid pressure in the high pressure port attains a predetermined pressure value, pumping means having a movable member connected to the piston means to be operated by movement thereof, and valved discharge means to exhaust the end of the cylinder means having the larger 10 piston means face, when said valve means is closed; 14.- Ina pump, a housing, cylinder means therein, piston means in the cylinder means having opposedoperating faces of different areas, a high pressure port in the housing connected to the cylinder means to apply, fluid under pressure to the. smaller face, passage means to connect said'highpressure port to the cylinder means to apply: pressureto the larger face, valve means controlling said passage means, yieldable force means actingonlsaid valve means to cause it to maintainithe passage means closed, a pressure chamber to receive fluid pressure from said high pressure port, to cause the valve to move against the force means and open the passage means when the fluid pressure in the high pressure port attains a predetermined pressure value, pumping means having a movable member connected to the piston means to be operated by movement thereof, valved discharge means to exhaust the end of the cylinder means having the larger piston means face, when said valve means is closed, and fluid pressure generating means connected to said high pressure port, and adapted to produce alternate high and low fluid pressures in said port, to effect opening of the valve means in response to high pressure conditions, and to permit closing thereof in response to low pressure conditions.

15. In a pump construction, a housing, cylinder means therein, piston means operable in the cylinder means and having opposed fluid pressure receiving faces, means continuously applying fluid pressure to the cylinder means to act against the first pressure receiving face to operate the piston in one direction, a high pressure fluid inlet port in the housing, passage means connecting the inlet to the cylinder means to apply fluid from the inlet to the second piston face, the high pressure on its piston face being adapted to produce a force greater than the opposing force on the first face, valve means in said passage means, yieldable force means normally closing said valve means, fluid pressure-responsive means to open the valve means, said fluid pressure-responsive means being connected to the high pressure inlet port to receive the fluid pressure therein and to open the valve means when said fluid pressure attains a predetermined high value to overcome said force means, and fluid pumping means connected to the piston means to be operated thereby.

16. In a pump, a housing, cylinder means therein, piston means operable in the cylinder means and having a fluid pressure receiving face, means continuously applying force to the piston means to move it in one direction, a fluid pressure inlet in the housing, a passage connecting the inlet to the cylinder to conduct fluid to the said face, valve means in said passage and movable to open and closing positions therein, yieldable force means normally urging the valve means into one of said positions, fluid pressure-responsive means acting on the valve means oppositely to the force means to move the valve means to the other of said positions, the fluid pressure means being connected to the fluid pressure inlet so that it moves the valve means in response to rise in pressure in said fluid pressure inlet, and fluid pumping means connected with the piston means to be operated thereby.

17. In a pump, a housing, cylinder means therein, piston means operable in the cylinder means and having a fluid pressure receiving face,

' means continuously applying force to the piston means to move it in one direction, a fluid pressure inlet in the housing, a passage connecting the inlet to the cylinder to conduct fluid to the said face, valve means in said passage and movable to open and closing positions therein, yieldable force means normally urging the valve means into one of said positions, fluid pressure-responsive means acting on the valve means oppositely to the force means to move the valve means to the other of said positions, the fluid pressure means being connected to the fluid pressure inlet so that it moves the valve means in response to rise in pressure in said fluid pressure inlet, fluid pumping means connected with the piston means to be operated thereby, said means continuously 15 1,907,947

applying force to the piston means comprising an opposing face on the piston means opposite the aforementioned face, and a fluid pressure passage connecting the inlet to the cylinder means to apply fluid pressure from the inlet to the opposing face.

FRANKLIN M. MACDOUGALL.

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

UNITED STATES PATENTS Name Date Gage May 9, 1933 Numb'er

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