High-pressure pump

Sept. 29, 1953

2,653,552

L. J. GEERAERT

HIGH-PRESSURE PUMP

Filed Aug. 15, 1951

Sheets-Sheet 1

<img file="US2653552A_D0001.tif" />

Sept. 29, 1953

2,653,552

L. J. GEERAERT

HIGH-PRESSURE PUMP

Filed Aug. 15, 1951 8 Sheets-Sheet 2

<img file="US2653552A_D0002.tif" />

L- J. GEERAERT

HIGH-PRESSURE PUMP

Sept. 29, 1953

Filed Aug. 15, 1951

2,653,552

Sheets-Sheet 3

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<img file="US2653552A_D0004.tif" />

<img file="US2653552A_D0005.tif" />

<img file="US2653552A_D0006.tif" />

Sept. 29, 1953

2,653,552

L. J. GEERAERT

HIGH-PRESSURE PUMP

Filed Aug. 15, 1951

Sheets-Sheet 4

<img file="US2653552A_D0007.tif" />

L. J. GEERAERT

HIGH-PRESSURE PUMP

Sept. 29, 1953

Filed Aug. 15, 1951

2,653,552

Sheets-Sheet 5

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Mvzzxez-zYirr·' , 2b&lt;m cY. (JeerYzerc

<img file="US2653552A_D0009.tif" />

Sept. 29, 1953

2,653,552

L. J. GEERAERT

HIGH-PRESSURE PUMP

<img file="US2653552A_D0010.tif" />

Sept. 29, 1953

2,653,552

L. J. GEERAERT

HIGH-PRESSURE PUMP

Filed Aug. 15, 1951

Sheets-Sheet 7

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Sept. 29, 1953

2,653,552

L. J. GEERAERT

HIGH-PRESSURE PUMP

<img file="US2653552A_D0012.tif" />

Patented Sept. 29, 1953

2,653,552

UNITED STATES PATENT OFFICE

2,653,552

HIGH-PRESSURE PUMP

Leon 3ean Geeraert, Brooklyn, N. Y., assignor to The Geeraert Corporation, New York, N. Y., a corporation of New York

Application August 15,1951, Serial No. 241,925

Claims.

The invention relates in general to fluid pumps and has for its principal object the provision of a high pressure pump applicable to various arts and industries but especially suited for use in pumping propellant-chemicals employed in the propulsion of rockets, guided missiles and aircraft, and for the operational discharge of flamethrower fuel.

In the propulsion of rockets, for example, use is made of fuming nitric acid, hydrogen peroxide, liquid oxygen, fluorine, high-test gasoline, alcohol, ammonia and sulphuric acid, which must be pumped at high delivery pressure with continuous, non-pulsating flow, and must not be exposed to the atmosphere either within the pump itself or anywhere in the conduction system. High pressure, non-pulsating discharge is particularly important in flame-thrower operation. A further complicating condition is the fact that some of the fluids in the above list cannot be pumped safely with conventional pumps of the reciprocating piston or rotary types wherein the fluid being pumped comes into contact with frictional surfaces of piston and cylinder, due to the danger of corrosion.

In the accomplishment of my primary object, I have made use of the fundamental principle of the flexible wall or diaphragm pump and have improved upon known pumps of this type by devising means for attaining sufficiently high pressure delivery and continuity of flow to meet all the exacting requirements which cannot be avoided when pumping propellant-chemicals and flame-thrower fuel, and to render the improved pump otherwise widely useful.

A further object of the invention is to provide a flexible wall pump for the intended purpose which is very compact in structure and possesses a minimum number of operating parts and yet is capable of pumping at high volumetric output capacity.

Another object is to provide a composite pump including a plurality of flexible wall units wherein the primary and secondary control valves for the respective units are so interlocked for synchronized sequential operation of the said units and actuated in direct response to flexible wall action that a high degree of pumping efficiency is attained.

A still further object is to provide a pile organization of individual flexible wall units arranged in-line, wherein the respective units are of interchangeable construction and are separably united in assembled relation in such a manner and by such means that the number of units (Cl. 103—152) necessary to afford a required volumetric output capacity may be assembled originally and then desired changes in capacity may be effected readily by simply adding or substracting units.

⁵ Further objects and advantages will become apparent as the following specific description is read in conjunction with the accompanying drawings, in which:

Fig. 1 is a partially diagrammatic cross-sectional view of a simplified form of diaphragm pumping unit constructed in accordance with the invention and having all-electric valve operating means, showing the flexible diaphragm midway between the limits of a suction stroke; and, Fig. 2 ¹⁵ is a similar view showing the midpoint of a pressure stroke.

Fig. 3 is a similar view of a pair of diaphragm pumping units of the same nature as that shown singly in Figs. 1 and 2 arranged abreast and rep²⁰ resenting the midpoints of a suction stroke in one unit and of a pressure stroke in the other; and, Fig. 4 is a similar view but showing reversal of strokes in the respective units.

Fig. 5 is a partially diagrammatic cross-sec²⁸ -tional view of a modified form of double unit, having long-thrust diaphragms and electrically actuated hydraulic pilot valves for operating the control valves, showing the midpoints of a suction stroke in one unit and of a pressure stroke in 30 the other; and, Fig. 6 is a similar view representing the reverse operational condition.

Fig. 7 is an end elevation of a short-thrust, multiple pile pump wherein a plurality of individual diaphragm pumping units are arranged in 35 axial alignment; Fig. 8 is a side elevation of the same; and, Fig. 9 is an exploded fragmentary side elevation thereof.

Fig. 10 is a partially diagrammatic horizontal cross-sectional view of a multiple pile pump of 40 the type illustrated in Figs. 7 to 9 but composed of only two piles of two diaphragm pumping units each, showing the pump in operation with one pile at the end of a suction stroke and the other at the end of a pressure stroke; and, Fig. 11 is a 45 similar view showing the reverse operational condition.

Fig. 12 is a large-scale axial cross-section view of a single diaphragm pumping unit of the shortthrust form illustrated in Figs. 7 to 11, wherein a 50 biasing and reinforcing spring is applied to the diaphragm thereof ; Fig. 13 is a fragmentary exploded view of the unit; and, Fig. 14 is a fragmentary perspective view of diaphragm and spring alone.

Fig. 15 Is an enlarged fragmentary front eleva

2,653,552 tion of the multiple pile cylinder of Figs. 7, 8, 10 and 11, partly broken away and in section to show portions of the various casing sections and other related elements in elevation; and, Fig. 16 is a similar view showing particularly the inner face of one of the casing sections.

Fig. 17 is a detail view in axial vertical crosssection of the flexible wall pumping units alone of a double-unit pump wherein the flexible wall is in the form of an elastic thimble-like tube closed at one end, showing the lefthand unit at the start of a pressure stroke and the righthand unit at the start of a suction stroke; Fig. 18 is a similar view showing the lefthand and righthand units respectively substantially midway during their pressure and suction strokes; and Fig. 19 is a similar view showing the lefthand and righthand units at the end of their respective pressure and suction strokes.

Fig. 20 is a vertical axial cross-sectional view of a complete double-unit pump embodying the elastic tube form of flexible wall but in a modified form, showing the lefthand unit approaching the end of a pressure stroke and the righthand unit at the completed end of a suction stroke; Fig. 21 is a similar view showing the lefthand unit at the end of a suction stroke and the righthand unit approaching the end of a pressure stroke; Fig. 22 is a horizontal cross-sectional view taken on line 22—22 in Fig. 20; Fig. 23 is an enlarged detail fragmentary view, partly in vertical section, of the upper end of one of the units at the end of a pressure stroke; and, Fig. 24 is an enlarged fragmentary view, partly in vertical section, of the control valve to show the dwell latch in detail.

Fig. 25 is a horizontal cross-sectional view similar to Fig. 22 of a quadruple unit pump of the same type as that shown in Figs. 20 to 24, inclusive.

Before proceeding with detailed description of my improved pump, it will be reiterated that, while the developed pump has wide general application in the arts and industries, I was expressly seeking to devise a pump especially suited for use with propellant-chemicals and flamethrower fuel for military purposes. Therefore, some of the exacting operational requirements peculiar to the specific employment I had in mind vail be more explicitly enumerated. For instance, the pressure on the fluid in the tank of origin from which it is to be pumped to another tank or other point of destination must not exceed that of the atmosphere (14.7 p. s. i. at sea level). In other words, pressurizing the tank of origin is forbidden. Furthermore, gauge pressure at the discharge side of the pump must be at least 100 p. s. i., and the condition of flow through the pump and all chambers or channels of the conduction system from tank of origin to point of destination must be such that cavitation and the resultant danger of vapor-lock are avoided.

As previously stated, I have chosen to adapt the fundamental principle of the flexible yzall pump to my purpose, one reason being that in such a pump there is no communication between the fluid being pumped and the driving fluid in the primary circulation system, whereby it is practicable to maintain the entire secondary conduction system for the propellant-chemicals and the like closed to the atmosphere.

The above-mentioned and other advantages of the flexible wall pump principle for my purpose should be fully appreciated upon consideration of the simple one-diaphragm pump unit constructed in accordance with the invention which is illus trated in Figs. 1 and 2 of the drawings. With the understanding that like reference characters indicate corresponding parts in the several views, the numeral 26 designates the pump casing, which is composed of two substantially identical circular dished sections 3t and 82 arranged to present their concave faces toward each other to form opposed working chambers 33 and 34, respectively, separated in a fluid-tight manner by flexible wall 3-5, which in this instance is a diaphragm. The flexible wall or diaphragm 35 is marginally clamped between the peripheral portions of casing sections 31—32 and is represented as being annularly corrugate in form and at the midpoint of its travel.

By using a separable flexible wall or diaphragm, it is practicable to make the said wall of a plastic or other specific material which will not be corroded or otherwise affected adversely by any particular propellant-chemical fluid. In like manner, the secondary section of the pump casing and all fluid conduits in the secondary conduction system may be made of stainless steel or other metals inert to the propellant-chemicals, whereas cast iron or other less expensive metals may be used in fabrication of all fluid conducting parts of the primary circulation system and the primary casing section.

Casing sections 38 and 32, respectively, are provided with two-way ports 36 and 37 communicating with the respective working chambers 33 and 35. These ports preferably are axially disposed and therefore in alignment. Control valves for ports 36 and 37, respectively, are indicated at 33 and 39. The respective casings 40 and 41 of control valves 38 and 39 preferably are formed integral with pump casing sections Si and 32 and have internal cylindrical chambers 42 and ¢3 in which valve plungers 44 and 45, respectively, are slidable longitudinally. For reasons which will appear presently, it is preferred to arrange valve chambers 42 and 43 in axial parallelism.

In the outer portion of valve casing 49 of control valve 38 there are two ports 46 and 47, which may be termed “pressure” and “suction” ports respectively because they are intended to be connected as shown with the respective pressure and suction lines 48 and 49 of a suitable primary circulation system (not shown) that generates power to drive the pump diaphragm 35. It is not considered to be necessary to disclose details of the said primary circulation system, for the reason that I am not claiming anything new in that system. Any conventional primary system with its prime mover (not shown) for generating pressure and suction conditions in the respective lines 48 and 43 will serve my purpose.

Valve plunger 44 of control valve 38 has an annular peripheral channel 58 which is of such axial -width and disposition that, when the plunger is in its righthand position shown in Fig. 1, it will span ports 47 and 36, and, when in its lefthand position (Fig. 2), -will span ports 48 and 36, whereby two-way port 3S may be connected selectively by longitudinal shifting of valve plunger 44 with either pressure port 46 or suction port 47.

Casing 4S of control valve 39 also has two ports Si and 52 which are intended to be connected as shown with intake line I and delivery line D of the secondary conduction system (not shown) that leads from the tank of origin (not shown) to the pump and thence to a point of destination (not shown). Valve plunger 45 also has an annular peripheral channel S3 of such axial width

2,β53.55β and disposition that, when said plunger is in its lefthand position shown in Fig. 1, it will span ports 51 and 37, and, when in its righthand position (Fig. 2), will span ports 52 and 37, whereby two-way port 37 may be connected selectively by 5 longitudinal shifting of valve plunger 45 with either intake port 51 or delivery port 52.

The respective plungers 44 and 45 of control valves 33 and 39 are shifted longitudinally by solenoids S' and 55, both of which have their 10 field coils connected in each of two parallel electric circuits. The fiield coil of one solenoid is wound oppositely to that of the other solenoid so that both solenoids will operate in opposite directions to move the valve plungers corre- 15 spondingly whenever current is caused to flow through either of said parallel circuits. The polarity of the two parallel circuits is controlled by reversing micro-switches of standard type 56 and 57. In other words, when micro-switch 57 20 is closed, as shown in Fig. 1, solenoid 54 will be energized in a manner which will shift plunger 44 of control valve 33 to the righthand limit, of its path of shifting movement, whereas simultaneous energization of solenoid 55 will shift 25 plunger 45 of control valve 39 in the opposite direction. Conversely, closing of reversing microswitch S6, as shown in Fig. 2, to reverse the polarity of current flowing through both solenoid field coils will shift the plungers of both 30 control valves in reverse directions to correspondingly change the direction of flow of fluids through said valves. It is to be understood, however, that the specific electric circuits represented in Figs. 1 and 2 are purely illustrative. Some 35 other circuit arrangement may be employed provided that the solenoids shift the respective control valve plungers in opposite directions alternately when the micro-switches are triggered into circuit closing condition. ₄₀

At this juncture, it may be appropriate to define some constantly recurring terms used in the specification and claims. For instance, the power imparting or driving fluid in the primary circulation system will consistently be called the 45 “primary fluid,” regardless of its specific nature. Similarly, the propellant-chemical or other fluid to be pumped through the secondary conduction system will be known as the “secondary fluid.” For the same reason, working chambers 33 and &lt;-._n34 of the pump will be called, respectively, the “primary working chamber” and the “secondary working chamber,” and control valves 38 and '39 will be termed the “primary control valve” and the “secondary control valve,” respectively. ₅₅

In this one-diaphragm embodiment of the invention, micro-switches 56 and 57 are triggered for automatic sequential shifting of the plungers of the primary and secondary control valves in opposite directions at the completion of each dia- 60 phragm stroke by means responsive to working· chamber pressure. For this purpose, each microswitch has a pressure-sensitive plunger or piston which is exposed to fluid pressure in the corresponding working chamber of the pump. For 65 this purpose, the pressure-sensitive plunger 56' of micro-switch 53 is located for longitudinal reciprocation in fluid duct 58 which communicates with the interior of primary working chamber 33 in the vicinity of port 36. Similarly, the pres- 70 sure-sensitive plunger 57' of micro-switch 57 is located for reciprocation in fluid duct 59 which communicates with the interior of secondary working chamber 34 close to port :37. Microswitch 5S is constructed and adjusted to be trig- 75 gered into close condition when the pressure in primary chamber 33 reaches a predetermined degree at the end of each upward suction stroke of diaphragm 35, whereas micro-switch 57 is constructed and adjusted to be triggered when the pressure in secondary working chamber 34 reaches a predetermined degree at the end of each downward pressure stroke.

The operation of the one-diaphragm unit should be understood upon further reference to Figs. 1 and 2. Assuming that the primary and secondary control valves 38 and 39 were shifted into the positions shown in Fig. 1 by reversal of the solenoid circuits as a result of automatic triggering of micro-switch 57 at the end of a preceding downward primary pressure stroke, primary working chamber 33 will have been opened to suction line 49 of the primary circulation system. This action permitted low pressure primary fluid to exert a suction effect on primary working chamber 33 and thereby commence to draw diaphragm 35 on its upward suction stroke. Fig. 1 shows diaphragm 35 at the mid-point of its travel in that direction. During this suction stroke, secondary fluid will be drawn into secondary working chamber 34 from secondary intake line I. At the end of the suction stroke just described, micro-switch 5S will be triggered automatically to cause reversal of current in solenoids 54 and 55, thereby shifting the plungers of primary and secondary control valves 38 and 39 into the positions represented in Fig. 2. As a result of this valve action, movement of secondary fluid from intake line I into secondary working chamber 34 will have been checked and said secondary working chamber will have been opened to secondary delivery line D as indicated. Simultaneously, primary working chamber 33 will have been opened to primary pressure line 48 to permit entry of primary fluid under high pressure. This action will cause diaphragm 35 to be thrust downward and thereby’force secondary fluid from secondary working chamber 34 into secondary delivery line D at high pressure. Fig. 2 shows diaphragm 35 at the midpoint of this downward travel.

When diaphragm 35 again reaches the downward limit of its travel in a pressure stroke, the two-stroke cycle of the pumping action will have been completed.

In the simplified, one-diaphragrn unit just described, delivery of secondary fluid through line D will be intermittent, there being suspension of flow in the delivery line throughout each suction stroke.

Referring now in detail to Figs. 3 and 4, continuous, non-pulsating flow in the delivery line has been achieved by virtually combining two of the simple pump units illustrated in Figs. 1 and 2 for coordinated operation through interlocking of the respective primary and secondary control valves thereof for sequential reciprocation of their plural diaphragms in opposite directions in a distinctly improved embodiment of the invention. It is as if the unit shown in Fig. 1 were used in the same position as lefthand unit A in Figs. 3 and 4, and as if the unit in Fig. 2 were reversed end for end horizontally and put in the position of righthand unit B in Figs. 3 and 4. The same reference characters for corresnonding parts have been retained, except that the letters a and b have been affixed to denote location in either unit A or unit B, respectively.

In order to effect the desired interlocking operation of the control valves, plungers 44a~44b

2,668,652 of primary control valves 38α—38b have been rigidly united for conjoined movement by connecting rod 60, and plungers 45α—45b of secondary control valves 39α—39b are similarly united by connecting rod 61. The desirability of arranging the working chambers of the control valves in parallelism should now be apparent. As a result, connecting rods 6B and 61 are free to reciprocate side by side in opposite directions when actuated by solenoids 54α—54b— 55α—55b in the manner which will be described presently in relation to the operation of the pump. In this instance, solenoids 54α—55b are electrically connected in series in one circuit and solenoids 55α—54b are in series in another circuit, the two circuits preferably being in parallel. There are only two micro-switches for the entire two-unit pump and, in this instance, both are triggered by predetermined pressure conditions in the secondary working chambers 33α—33b only at the ends of the respective pressure strokes, which is a distinct advantage under some pumping conditions because valve shifting cannot take place before complete evacuation of secondary fluid. However, in certain situations, synchronization of motion of the two diaphragms may not be obtained, thereby necessitating the use of micro-switches in the primary chambers as well as in the secondary chambers, in which case both switches for each unit would be electrically connected in series to avoid low volumetric efficiency.

Operation of the double-unit pump disclosed in Figs. 3 and 4 will now be described. Referring first to Fig. 3, it will be observed that diaphragm 35α of the lefthand unit A is at the midpoint of its upward suction stroke while secondary fluid is being drawn from secondary intake line I, whereas diaphragm 35b of righthand unit B is midway in its downward pressure stroke in which secondary fluid is being forced into secondary delivery line D. When diaphragm 35b of unit B reaches the end of its downward pressure stroke, the pressure in duct 59b will have attained the predetermined degree for triggering of micro-switch 57b. When this occurs, the electric circuit of solenoids Εβα and 55b will be closed (indicated by heavy circuit lines in Fig. 3) to cause valve plungers 5ία—44b and 45α—45b to be shifted simultaneously in opposite directions into the dwell positions shown in Fig. 4. Immediately upon reversal of the control valves at the end of the pressure stroke in unit B, unit A will commence instantly to force into secondary delivery line D the increment of secondary fluid that was drawn into working chamber 34α during the preceding suction stroke. Simultaneously, unit B will be undergoing a suction stroke. Now, when diaphragm 35α of unit A completes its upward pressure stroke, the pressure in duct 68α will have attained the predetermined degree for triggering of micro-switch 56α. When this occurs, the electric circuit of solenoids 55α and 54b will be closed (heavy circuit lines in Fig. 4) to cause valve plungers 44α—44b and 45α—45b to be shifted reversely into the dwell positions shown in Fig. 3, thus completing the cycle of operation. It should be obvious that in this doubleunit pump there will be uninterrupted, nonpulsating flow of secondary fluid in the delivery line as compared with the pumping action of the single unit disclosed in Figs. 1 and 2.

In Figs. 5 and 6, there is illustrated a doubleunit pump of modified construction. This embodiment of the invention differs from that dis8' closed in Figs. 3 and 4 principally in the form and size of each pump casing and the flexible walls therein, the increased length of stroke and proportionately greater displacement, the substitution of fluid-pressure for solenoid action as the direct actuating means for the control valves, and the use of mechanical diaphragm-contacting trigger devices.

The casing sections 3i—32 of both units A and B are bell-shaped and the flexible walls or diaphragms 35—35 are of similar shape, whereby long-stroke, high-displacement pumping action is achieved. The control valves 38—39 are identical in construction and arrangement with those in the Figs. 3 and 4 embodiment, but their plungers 44α—44b—45α—45b are not affixed to the solenoid cores. Instead, the cores of the primary solenoids 54α and 54b of the respective units A and B are affixed to pilot valve plungers 62α and 62b respectively, which operate reciprocatingly in valve sleeves 63α and 63b located across the outer ends of valve cylinders 40α and 49b and constituting cylinder heads therefor. Similarly, the cores of secondary solenoids 55α and 55b of the respective units A and B are affixed to pilot valve plungers 64α and 64b respectively, which are adapted to reciprocate in valve sleeves 65α and 65b located across the outer ends of valve cylinders βία and 4ib and constituting cylinder heads therefor. Each valve sleeve 63α— SSb—S5a—-65b has two axially spaced diametrical ports 6B and 67 which pierce the inner and outer walls of the respective sleeves in axial registration with the respectively adjacent outer ends of the corresponding working chambers of the control valves 38—39. Each of the valve plungers G2a—62b—S4a—64b has a diametrical port 68 which is adapted to register with and interconnect the inner and outer wall portions of port 66 when the said valve plunger is in its elevated position and to register- with and interconnect the inner and outer wall portions of the other port G7 when the plunger is in its outwardly projected position. Valve plungers 62α—$2b— 64α—84b gravitate into their depressed positions when the fields coils of solenoids 54α and 54b become de-energized, whereas energization of said solenoids serves to raise the respective valve plungers to their elevated positions.

Due to the modification just described, plungers 44α—44b and 45α—45b of the respective control valves 38α—SSb and 39α—-39b have also become pistons which may utilize the motive power of primary fluid in primary pressure and suction lines 48 and 49 as means for causing their operative reciprocation in the performance of their original control functions in relation to ports 46—47—3S and ports 51—52—37. Shifting of the piston-plungers 44α—44b and 4Ea—45b back and forth in opposite directions in interlocked relation through utilization of the primary fluid is now under the control of pilot valves 69α, 69b, ΪΒα and 78b, of which: valve 69α is constituted by parts 62α—63α—66α—87α—S8a operated by solenoid 54α; valve 89b is constituted by parts 62b—63b—SSb—S7b—SSb operated by solenoid 64b; valve 70α is constituted by parts S4a—Sea— S6a—si_a—operated by solenoid 55a; and valve 79b is constituted by parts 04b—SSb— 66b—&amp;tb—68b operated by solenoid 55b.

In order to connect the respective pilot valves of unit A with primary fluid, ports 66α—66α of valves 69α—ΊΟα are connected direct to primary pressure line 48 by duct forming means 72 α, and ports 67α—67α of said valves are connected di2,653,552 rect to primary suction line 49 by duet forming means 71α. Similarly in pump unit B, ports 66 b—66b of pilot, valves 69b—70b are connected direct to primary suction line 49 by duct forming means 7!b, and ports 67b—67b of said valves are connected direct to primary pressure line 48 by duct forming means 72b.

.While in the diagrammatic representation of Figs. 5 and 6 the duct forming means 71 a—12a— lib—12b is in the nature of external tubing, it is within the scope of the invention to substitute internal ducts cast or drilled in the pump casing.

Synchronized triggering of the pilot valves of pump units A and B, respectively, is accomplished automatically by micro-switches 73α and 73b, which are installed in the outer end portions of working chambers 34α—34b and have springretracted (opening) pushbuttons 74α—74b, respectively, which normally project into the interior of said chambers in the path of said flexible walls when the switches are open. Contact of the flexible wall of one of the units with the corresponding pushbutton at the end of its pressure stroke will serve to close the micro-switch of which said pushbutton forms a part. Thereafter, movement of the flexible wall in reverse direction (suction stroke) will permit the switch to open automatically through spring action. Micro-switch 73α serves to open and close parallel electric circuits 75 and 76 which are energized by battery 77 or other suitable source of current. The field coils of solenoids 54b and 55α are connected in circuits 75 and 76, respectively. On the other hand, micro-switch 73b serves to open and close parallel electric circuits 78 and 79 which also are energized by source 77. The field coils of solenoids 54α and 55b are connected in circuits 78 and 79, respectively.

Although counteracting fluid pressures will tend to secure the piston-plungers of the respective control valves in their different dwell positions assumed at the end of each pressure stroke, it is desirable to supplement the pressure means by more positive mechanical means. Any suitable latch means may be adopted for this purpose, but I have shown, for purposes of illustration, the simple spring-urged detents 80 and 81 which enter the alternative notches 82 and 83 provided in connecting rods 68 and 6i, respectively. These dwell latches, as they may be termed, will become disengaged readily when the valve piston-plungers are subjected to pressures of primary fluid in the same direction through operation of the appropriate pilot valves.

The operation of the modified pump will now be described. Whereas plungers 62α—62b—64α__

S4b of the respective pilot valves 69α—69b— 70α—78b are all in their depressed positions throughout almost the entire period of each stroke of the pump, they will be operated selectively at appropriate times during each operational cycle. Assuming now that flexible wall 35a of unit A has just completed its downward pressure stroke at the end of a cycle, contact of the said flexible wall with plunger 74α of micro-switch 73α will have triggered pilot valves. 69b and 70α by closing the circuits of solenoids 54b and 55α, respectively. Triggering of pilot valves 69b and 70α causes plungers 62b and 64α, respectively thereof to be thrust into their elevated positions shown in Fig. 5. When this happens, the left end of chamber 43α of control valve 39α is opened through ports 66—68 and duct forming means 71α to primary suction line 49, which will cause coupled ccntrol valve piston-plungers 45α—45b to shift to the lefthand dwell position shown. There will be no hydraulic resistance to this movement because the outer (right) end of chamber 43b of control valve 39b will still be open to communication with primary pressure line 48 as shown. At the same time, the right end of chamber 42b of control valve 38b will be opened through ports 66—68 and duet forming means 71b with primary suction line 49. Since the left end of chamber 42α of control valve 38α is still in communication with primary pressure line 48, the desired shifting of coupled control valve piston-plungers 44α and 44b to the righthand dwell position shown will occur.

It is not so shown in Fig. 5, but plungers 62b and 64α of pilot valves 69b and 70α will have gravitated into their depressed positions just as soon as the pushbutton 74α of micro-switch 73α has been released by flexible wall 35α at the start of its upward suction stroke toward the midposition actually shown. Upon return of plungers 62b and 64α of pilot valves 69b and 70α to their depressed positions (not shown), the right end of chamber 42b of control valve 38b and the left end of chamber 43α of control valve 39α will both be opened to primary pressure line 48, but the pressure thereof will be balanced by the same pressure to which the opposite ends of pistonplungers 44α and 45b of control valves 38α and 39b, respectively, are subjected because pilot valves 69α and 70b are always open to pressure when their plungers are depressed. In fact, all pilot valves are open to pressure when their plungers are depressed and open to suction when their plungers are elevated through energization of their respective solenoids.

At the end of the first stroke of the pumping cycle under consideration, flexible wall 35b will have closed micro-switch 73b to energize solenoids 54α and 55b and thereby open the left end of chamber 42α and the right end of chamber 43b to primary suction, as shown in Fig. 6, which will cause coupled control valve piston-plungers 44α—44b to shift to the lefthand’ dwell position shown in Fig. 6 and the coupled control valve piston-plungers 45α—45b to shift in the opposite direction to the righthand dwell position shown. Of course, by the time the flexible walls 3ξ,α—35b have reached the mid-positions shown, solenoids 54α and 55b will have become de-energized and pilot valves 69α and 70b will have been opened to primary pressure. The cycle will be completed when flexible walls 35α and 35b have reached the ends of their respective pressure and suction strokes shown in Fig. 6.

Figs. 7 to 16, inclusive, illustrate the preferred embodiment of the invention, which achieves a high degree of simplicity, compactness, efficiency of operation, and versatility. In brief, the casing sections of each pumping unit are in the form of flat, comparatively thin, circular plates having very shallow working chambers and short-stroke flexible diaphragms. These plates, in the required. number and cooperative combinations, are adapted to be bound together in a compact in-line pump organization to afford the required number of piles for a particular volumetric output capacity which may be needed. To increase or decrease the capacity, all that is necessa.177 is to add or subtract one or more diaphragm chambers. Furthermore, all units are identical in structure and thus interchangeable. A partic2,663,659 .Π ular advantage of this interchangeability is the facility with which casing sections and diaphragms of different composition may be exchanged to accommodate propellant-chemicals of different corrosion characteristics.

As shown in Figs. 7 and 8, in particular, the completely assembled “in-line” organization of piles has the general form of a cylindrical casing 80' disposed with its axis horizontal on a flat supporting base 8 i' of suitable length and anchored to the latter in a manner which will be described presently.

Turning now to Figs. 10 and 11, it will be observed that the illustrative pump organization comprises two piles and thus may be termed appropriately a “twin pile pump.” The two piles are located on opposite sides of an anchor plate 82' which is suitably affixed to base 81' midway between its ends, and head plates 83' and 84 embrace the outer ends of said piles. As shown in Figs. 7 to 9, the assembled piles and plates 82', 83' and 84 are clamped together in precise alignment and rigidity by tie bolts 85.

Each pile comprises two pump casing units (Figs. 10 and 11) and each unit in turn is composed of mated casing sections §8 and 87 which are circular in general form and nearly identical in specific structure. One of the units is shown clearly in detail in Figs. 12 to 14. The left-hand casing section 85 (Figs. 12 and 13) has a comparatively shallow concavity formed in its inner (right) face to constitute the primary working chamber 88 of the unit. (Compare the axial depth of chamber 88 with that of the corresponding chambers represented in Figs. 5 and 6 or even in Figs. 1 to 4.) The shallow secondary working chamber 89 formed in the inner (left) face of casing section 87 differs from primary working chamber 88 principally in the provision of an annular depression 90' of uniform depth which extends radially inward from the peripheral margin of said chamber approximately half-way to its central axis. Casing section 86 is provided with an annular groove 9i around the margin of primary working chamber 88. This groove 88 has a cylindrical peripheral wall 92 and preferably serrated side face 93. Casing section 8 has a narrow and deep cylindrical groove or cut 94 substantially flush with the outer wall of groove 91 of section 88.

Circular flexible diaphragm 95 separates primary working chamber 88 from secondary working chamber §9 and has its marginal edge gripped between casing sections 8S and 87 when assembled. A serrated marginal bead 96 on diaphragm 95 is adapted to fit snugly and securely in groove Si.

Casing sections 86 and 87 are provided with central grilled ports 97 and 98, respectively, of large cross-sectional area. Casing section 86 also has a shallow annular cavity or depression 99 in its outer face surrounding port 97 in preferably eccentric relation thereto. Leading radially outward from the outermost part of cavity 99 is an outwardly enlarged groove ί 00 of semicircular cross-section which opens through the peripheral edge face of casing section 86. Port 97, cavity 80 and groove ί 00 are so constructed and arranged that they will register with these same indentations in the adjacent casing section 86 of the cooperative unit of a pile when assembled in the closely abutting relation shown in Figs. 10 and 11. In this assembled relation, cavities 99—99 and grooves 100—100 of both abutting casing sections 86—86’ unite to form, cir12 cular radial conducting passages i 01 for primary fluid.

Each casing section 87 has a shallow, eccentric cavity 182 in its outer face surrounding port 98. From the outermost part of cavity 102, a radial, outwardly enlarged groove (03 of semi-circular cross-section leads to and opens into an axial passage (0'4 located near the periphery of said casing section 87. Actually, cavity 99 and groove i99 of casing section 88 are identical in form with cavity 102 and groove (03 of casing section 87, but, in the assembled relation of both casing units of a pile (Figs. 10 and 11), they are disposed so that grooves (00 and 193 extend in diametrically opposite directions from the pile axis. Casing section 88 also is provided further with an axial passage (95 near its outer peripheral edge which is adapted to register with passage (84 of casing section 87 when said sections are assembled. A short radial groove (06 of semi-circular crosssection leads outward from the outer end portion of passage ! 04 through the peripheral edge face of casing section 8S. In the assembled relation of both casing units of a pile, the grooves (06—106 of the abutting sections 8S—86 of said casing units combine to form a circular passage (07.

It having been found in practice that the most suitable hydraulic pump for use as prime-mover (not shown) in the primary circulation system was incapable of pulling more than from one to three pounds of vacuum (13.7-11.7 PA), the pressure differential between the primary side of a pump diphragm during a suction stroke and the pressure in the tank of origin (atmospheric pressure) is only about one to· three pounds. Therefore, in order to compensate for the low suction pressure and to insure a quick, nonlagging suction stroke of each diaphragm, I have added suction-stroke bias to each diaphragm by applying thereto spring means which Is shown in detail in Figs. 12 to 15, inclusive. A practical embodiment of the biasing means just mentioned is the generally annular spring (08 which includes a circumferential base ring (69 adapted to have its opposite side edge portions fit in grooves 0( and 94 of casing sections 86 and 87 when assembled to form a casing unit. A web ! (0, which lies in a plane prependieular to the casing axis, projects inward from base ring (09 and is adapted to be disposed on the secondary working chamber side of diaphragm 95. Web 1(9 is provided with substantially radial fingers ί ί i projecting inward therefrom. In order to increase the flexibility of fingers (II, they are provided with longitudinal slots 1(2 which open into holes 1(3 located in web (ί 0 close to· base ring (09. Considerable space between fingers is required in order to prevent overlapping of the fingers and danger of pinching the diaphragm while passing dead center.

Biasing spring 108 is shown in its normal preformed relaxed condition in solid lines in Fig. 13 and in broken lines in Fig. 12, wherein its fingers conform in arcuate shape to the concave wall of primary working chamber 88. In Fig. 14 and in full lines in Fig. 12, fingers ((f of spring (93 appear in the sprung, fully tensioned position into which they will have been forced by diaphragm 95 at the end of a pressure stroke. In this tensioned condition, fingers I (I will be sheltered in an out-of-the-way position in depression 90 to permit closing contact between diaphragm 95 and the concave wall of secondary ¹ working chamber 89.

2.653,552 solenoids 139 and 140. When, energized, solenoid i 33 is adapted to move valve plunger 13.1 to. the right and solenoid 140 is adapted to shift said plunger in the opposite direction.

A micro-switch 14! is mounted on head plate 83' and has a pushbutton 141' projecting normally into, secondary working chamber 89 of the adjacent pump pile when said switch is open for actuating- contact by the adjacent diaphragm 95 10 at the completion of its pressure stroke. Microswitch 141 is connected electrically with solenoids 127 and 149 in such a manner that closing of the switch will energize both of said solenoids and thereby cause primary and secondary valve 15 plungers 118 and 13! to be shifted synchronously in opposite- directions into their respective lefthand and righthand dwell positions.

A micro-switch 142 is mounted on the opposite head plate 84 and has a pushbutton 142' pro20 jecting normally into secondary working chamber 88 of the adjacent pump pile when said switch is open for actuating contact by the adjacent diaphragm 95 at the completion of its pressure stroke. Micro-switch 142 is connected electri25 cally with solenoids 128 and 133 in such a manner that closing of the switch will energize both of said solenoids and thereby cause primary and secondary valve plungers 118 and 131 to be shifted· synchronously in opposite directions into their respective righthand and lefthand dwell positions.

The operation of the twin pile should be understood readily upon further reference to the two operating cycles represented in Figs. 10 and 11. Big. 10 shows the diaphragms and interlocked control valve settings at the end of a cycle in which ths two cooperative diaphragms of the lefthand pile have just completed their joint pressure stroke, in which they moved apart from 40 each other, and the two cooperative diaphragms of the righthand pile have just completed their joint suction stroke, in which they closed toward each other. Valve plungers I ί 8 and ! 31 are shown during the instant when micro-switch 45 141 is closing the circuits of solenoids 127 and ¢40 and the latter are on the point of shifting said valve plungers in opposite directions to the new dwell positions represented in Fig. 11.

When the shift occurs, control valve I! 5 will 50 connect primary working chambers 38—88 of the lefthand pile with primary suction line 48 through the medium of port 123, plunger channel 125, passage 101, and both ports 97—97. Simultaneously, control valve 115 will connect pri55 mary working chambers 88—88 of the righthand pile with primary pressure line 49 through the medium of port 124, plunger channel 12S, passage 101, and both ports 97—97. Application of suction and pressure in this manner will 60 cause the cooperative diaphragms of the lefthand pile to close toward each other into the positions shown in Fig. 11, whereas the diaphragms of the righthand pile will move apart into the positions shown. During this motivat65 ing action by primary fluid, secondary fluid will be moved in the direction of the arrows in Fig. 11, i. e. secondary fluid will be drawn from secondary intake line I in the direction of the arrows through port 136, valve channel 137, port 70 133, passages 107—104—114, and both ports 98—98 into secondary working chambers 89—89 of the lefthand pile. At the same time, previously captivated secondary fluid will be pressurized and then expelled in pressurized condi75 tion from secondary working chambers 89—89

In addition to the primarily intended biasing of diaphragm 95, spring 108 serves other useful purposes. It tends to preserve the smooth shape of diaphragm 95 and prevent excessive deformation such as would be likely to result eventually in creasing and rupture; and it absorbs and conducts heat from the diaphragm to the peripheral portions of the casing for external radiation.

Referring again to Figs. 10 and 11, it will be observed that the adjacent faces of anchor.plate 82' and of head plates 83' and 84 cooperate with cavities 102 and grooves 103 of casing sections 87 to wall them in completely and thereby provide radial fluid passages 114.

The primary and secondary control valves 115 and I! G for the twin pile preferably are located in horizontal parallelism on opposite sides of the cylindrical casing 80'. Primary valve 115 includes a tubular casing 117 closely abutting the peripheral edges of the respective sections of all casing units. Valve casing 117 may be supported by plates 82'—83'—84 in any manner which may be expedient. A single elongated valve plunger I ί 8 is mounted to reciprocate in the interior chamber 119 of valve casing 117 from one extreme dwell position to the other. Suitable detent means 120 is provided to secure valve plunger I i 8 yieldably in either dwell position until overcome by the operating force which shifts said valve plunger in its normal operation. Ports 12 i and 122 are provided in valve casing 117 for registration with the respective passages 191—101 of the lefthand and righthand piles which make up the twin organization. Primary suction and pressure ports 123 and 124 are provided in valve casing 117 adjacent to each of passages iOS—151 for connection to the respective suction and pressure lines 48 and 49 of the primary circulation system. Valve plunger 118 has appropriately spaced annular peripheral grooves or channels 125 and 126 which, in the righthand dwell position of said plunger (Fig. 10), are adapted to span and thereby interconnect ports 121—49 and ports 122—48, respectively, and, in the opposite lefthand dwell position (Fig. 11) to span and interconnect ports 121—48 and ports (22—49, respectively.

Valve plunger 118 is affixed to the cores of solenoids 127 and 128. When energized, solenoid 1’7 is adapted to move valve plunger 118 to the left, and solenoid 128 is adapted to move said plunger in the opposite direction.

Control valve 116 also includes a tubular casing 129, in the chamber 130 of which elongated valve plunger 131 is mounted, to reciprocate between extreme dwell positions. Suitable detent means 132 also is provided to secure valve plunger 131 yieldably in either dwell position. Ports 133 and 134 in casing 129 are positioned to communicate with passages 107—107 of the respective lefthand and righthand piles of the composite twin. Primary delivery and intake ports 135 and 136 are provided in valve casing 129 adjacent to each of the ports 107—107 for connection, respectively, with secondary delivery line D and intake line I. Valve plunger 131 is provided at appropriate intervals with peripheral annular grooves or channels 137 and 138 which, in the lefthand dwell position (Fig. 10) are adapted to span and thereby interconnect ports 135—133 and ports 136—134, respectively, and, in the opposite righthand dwell position (Fig. 11), to span and interconnect ports 136—133 and ports 135—134, respectively.

Valve plunger 131 is affixed to the cores of

2,653,552 of the righthand pile in the direction of the arrows through ports 98—98, passages f 14—105— 107, ports 134, valve channel (38, and port 135 into secondary delivery line D.

At the end of the second cycle represented in Fig. 11, the pushbutton 142' of micro-switch (42 has been pushed inward by the adjacent diaphragm 95 and solenoids (28 and 139 are going into action to reverse the interlocked control valves ί 15 and ((6 and thereby start the diaphragms of the respective piles through the cycle represented as just ending in Fig. 10. During this two-stroke cycle, the primary and secondary fluids moved in the direction of the arrows.

It should now be understood that in the twin pile illustrated in Figs. 10 and 11, the cooperative pairs of diaphragms of both piles pulsate in a bellows-like action alternately toward and away from each other. The stroke is very short, but maximum volumetric output capacity is realized for the small size and weight of the pump as a whole. Due to this characteristic, the multiple pile organization renders the pump well suited for installation in the cramped interior of rockets and other aerial projectiles and aircraft for use in delivering propellants from contained tanks to burners or other delivery points either preceding flight or during flight under radio control, as well as for external use with ground equipment. A still further use for which the. multiple pile pump is well suited is for pressurizing of fuels in the servicing of large military flame throwers.

In Figs. 17 to 19, inclusive, there are shown in three successive operational stages the flexible wall units alone of a modified double-unit pump, wherein the flexible walls are elastic as well as flexible and are intended to function through alternate distention and contraction.

Referring first to Fig. 17, the double-unit pump comprises lefthand unit A and righthand unit B, which retain their relative positions in Figs. 18 and 19. Both units are identical in construction when in the condition represented in unit A (Fig. 17) in which the flexible wall member is contracted. The respective casings 143α and !4&lt;3&amp; are open-ended cylinders having reduced externally screw-threaded necks (44α—(44b and (45α—(4Bb at their lower and upper ends, respectively, for engagement with clamping rings (46α—(46b and (47α—(47b which secure said casing necks (44α—(44b and (45α—(45b, respectively, to the externally flanged necks (40α and !48b of two-way primary ports 149α and (49b and to similar necks (59α and (SOb of secondary ports 15(a and !5!b of the respective primary and secondary control valve casings (not shown). At the lower base ends of casings (43α and (43b, the externally flanged base ends of tubular collapse-preventing forms 152α and (52b are clamped between the externally flanged ends of port necks 150α and 150b and the lower edges of casing necks (44α and (44b, respectively. These collapse-preventing forms !52a and (52b project into casings (43α and (43b and extend throughout almost the entire length of the interior of said casings. Forms (52α and 152b have numerous fluidpenetrable perforations (53α and (5-3b from their bases to their upper ends, which latter are provided with smoothly convex caps (54α and 154b having central perforations (55α and (55b therein. Enclosing collapse-preventing forms (52α and (52b are flexible wall members (5Sa and 156b, respectively, which are thimble-shapsd in form and, in their normal relaxed condition, closely fit the respective collapse-preventing forms in the manner shown in the lefthand unit , A (Fig. 17), wherein the closed upper end of flexible wall member (56α is seated on cap (54α of form (52α. The open base ends of flexible wall members (56α and 15§b are tightly gripped between the downwardly flared outer surfaces I of the base portions of collapse-preventing forms (52α and (52b, respectively, and the internal surfaces of the casing necks (44α and !44b, which are correspondingly outwardly flared. To make the connection of the base &gt; portions of flexible wall members (56α and 156b with casing necks (44α and ί 44b even more secure, the former are downwardly thickened and externally serrated for interlocking engagement with correspondingly serrated inner surfaces of ! the latter.

An important structural feature of flexible wall members 156α and ί 56b is the fact that they are made of elastic material, such as rubber or a rubber substitute. Moreover, the closed upper , ends of said flexible members are axially thickened to prevent deformation in action and their side walls are gradually tapered in radial thickness aownwardly from the thickened upper ends thereof to the base portions. The tapered thick-, ness of the side walls of each flexible wall member serves to propagate distention progressively upward from the base during a pressure stroke and, conversely, to propagate contraction downward toward the base during a suction stroke as will be explained more fully hereinafter.

Flexible wall members (56α and i 36b are fluidimpervious and sealed so tightly at their bases m the manner already described that they effectively divide the respective casings (43α and (43b into radially inner and outer primary and secondary working chambers !S7a—(57b and 158α—158b. Obviously, when flexible wall member 156α of lefthand unit A is in its fully contracted condition as shown in Fig. 17, primary working chamber 157α is restricted to the interior chamber of collapse-preventing form (52α, whereas in the righthand unit B, in which flexible wall member (56b is fully distended, primary working chamber (57b will occupy practically the interior space of casing (43b while secondary working chamber 158b will have been reduced to zero capacity.

At the.upper ends of casings (43α and (43b, micro-switches (59α and (5Sb are located for use in connection with the control valve operating circuits (not shown) and have their respective pushbuttons (69α and (SOb projecting into the respective secondary working chambers ί 58α and (58b for triggering contact by the upper ends of flexible wall members (5Sa and (56b. in order to insure positive and instantaneous switch actuation, the upper ends of flexible wall members (56α and (56b are provided with metallic rings embedded in their outer surfaces for direct hard pushbutton contact.

Operation of the double-unit puma’s flexible wall.members will be understood upon reference to Figs. 17, 18 and 19 in that consecutive order. Fig 17 represents the operational stage at the instant a pressure stroke is commencing in casing. (43α and a suction stroke is commencing in casing (43b. In Fig. 18, partial progress in these simultaneous pressure and suction strokes is represented. In the lefthand casing (43α, pressure m primary chamber (57α is distending flexible

2,663,552 wall member 156α. Because the upper portions of the side walls of said member 156α are thicker than the lower portions and because the increase in thickness is graduated, the lower portions will become distended first since they offer the least resistance to radial pressure. Consequently, the complete distention of flexible wall member i 56α is propagated steadily upward without any inefficient, fatigue-producing irregularities in flexible wall action. The same thing occurs in reverse order in the opposite suction stroke represented in the righthand casing 143b. In this case, the thicker upper side wall portions of flexible wall member 156b have a stronger contractional tendency than the thinner lower side wall portions, so the contraction is propagated downward in regular progression. Fig. 19 represents completion of the pressure and suction strokes of flexible wall members 156α and 156b in the respective casings 143α and 143b, and, shows the microswitch 159α in the act of being triggered for control valve reversal.

Figs. 20 to 24, inclusive, illustrate a modified form of the type of pump disclosed in Figs. 17 to 19. In this instance, the complete pump is shown. The casings 16la and 16lb differ from casings 143α and 143b of the other embodiment principally in the relative dispositions of the secondary ports and the micro-switches and in the form of flexible wall members 162α and 162b. The upper ends of casings 161α and 161b are closed to form rounded domes (63α and 163b and render the casings generally bottle-shaped, and the secondary ports are located substantially midway between the ends of the casings. In this embodiment of the invention, there are two secondary ports for each casing, i. e. casing 16la and casing ! 6 ib have secondary intake ports !64a and 164b, respectively, connected with secondary intake lines I—I, and secondary delivery ports 165α and 165b connected with secondary delivery lines D—D. Because of this arrangement with no intervening control valves, the respective secondary intake and delivery line connections must have suitable check valves (not shown) to prevent retrograde flow therein.

A single double-acting control valve 166 is provided in the base 167 on which casings 16la and I6ib are mounted in upright coextensive positions. This control valve has a horizontally elongated valve chamber 168 underlying both casings 161 and 16lb and provided with two-way ports 16Sa and 169b communicating with the lower ends of the respective collapse-preventing forms 170α and 170b. Primary pressure and suction ports 171 and 172 are provided respectively below and above the mid-portion of valve chamber 168 for connection with the respective primary pressure and suction lines 173 and 174. Primary pressure port 171 is branched to communicate with valve chamber 168 through two longitudinally spaced mouths. Similarly, suction port 172 is branched to communicate with valve chamber 168 through longitudinally spaced mouths in vertical registration with the mouths of port 171.

A valve plunger 175 is mounted to slide back and forth longitudinally in valve chamber 168 between the two terminal dwell positions shown in Figs. 20 and 21, respectively. A spring-pressed dwell-latch 176, such as that shown in Figs. 20 and 21 in reduced size and on a large scale in Fig. 24, is provided in control valve 166 to secure valve plunger 175 yieldingly in either dwell position. The bottom face of valve 175 is of such construction and longitudinal extent that it will cover one mouth of pressure port 171 and open the other mouth thereof to the interior of valve chamber 168 in one dwell position of said plunger and will reverse the connection of port mouths and valve chamber in the opposite dwell position. The upper face of valve plunger 175 has longitudinally spaced channels 177—177 which are so positioned that, in the dwell position wherein pressure port 171 is in communication with port 169α of casing 161α (Fig 20), suction port 172 will be in communication with port 169b of casing 161b, and, in the opposite dwell position, wherein pressure port 171 is connected with port 169b of casing 161b (Fig. 21), suction port 172 will be in communication with port 169α of casing 161α.

The cores of solenoids 178 and 179 are affixed to opposite ends of valve plunger 175 and are so wound and arranged in electric circuits (not shown) controlled by micro-switches 180 and 181 that shifting of said valve plunger back and forth in synchronization with completion of each pressure stroke by flexible wall members 162α and 152b, respectively, is effected.

It will be observed that both micro-switches are located substantially at the same level as secondary ports 164α—164b and 165α—165b. At this level, the pushbuttons 180' and 181' of microswitches 180 and 181, respectively, project into the secondary chambers of casings 161α and 161b form contact with the midportions of flexible wall members 162α and 162b, respectively, upon completion of their pressure strokes. In this instance, flexible wall members 162α and 162b both have their side walls centrally thickened and tapered in thickness toward the upper and lower ends thereof. Due to this wall structure, pressure of primary fluid during a pressure stroke will be exerted through the interior of collapsepreventing form 17Sa or 170b, as the case may be, against both thin end portions of the side walls of the flexible member concerned in the beginning to commence distention in these regions. Thereafter, the distention will be propagated axially inward toward the thickened medial portion. Reverse propagation of contraction progresses endward from the center in a suction stroke.

The operation of this modified form of doubleunit pump will now be described. Fig. 20 represents the operational stage wherein lefthand unit A is approaching the end of a pressure stroke and righthand unit B is at the end of a suction stroke. A moment later, when the pressure stroke has been completed, the thickened midportion of flexible wall member 162α will have contacted pushbutton 188' and thereby closed micro-switch 188. When this occurs, control valve 166 will be shifted to the dwell position represented in Fig. 21 to reverse the strokes in the manner shown.

Fig. 25 illustrates a quadruple-unit pump and has been introduced to demonstrate the compact construction which may be achieved when doubling the capacity of the type of pump disclosed in Figs. 20 to 24. Only the general organization of casings of the two double-unit pumps which have been combined is shown. In this embodiment, it is as if a second double-unit pump of that kind were moved into position directly alongside (beneath in Fig. 25) the pump disclosed in Fig. 22. Casings 182α and 182b in Fig. 25 correspond to casings 161α and 16 fb in Fig. 22. To these casings 182α and 182b have been added the casings 183α and 183b of the sec

2,653,552 ond pump. The principal departure lies in the rearrangement of the secondary lines and their connection with the various secondary chambers of the quadruple-unit pump. For example, secondary intake lines I—I independently communicate with the secondary chambers of casings 182α and 182b on one side of the pump and with the secondary chambers of casings 183α and 183b on the opposite side, as shown. One Y-shaped delivery line manifold D is connected with the secondary chambers of casings 182α and 183α and a second Y-shaped delivery line manifold D' is connected with the secondary chambers of casings 182b and 183b at the opposite end of the pump. The manner in which this modified pump operates should be obvious without further illustration or description.

It will be understood that it is intended to cover all changes and modifications of the examples of the invention herein chosen for the purpose of illustration which do not constitute departures from the spirit and scope of the invention.