Diaphragm Pumps And Actuating System Therefor

Abstract

An improved fluid pressure-actuated timer controlled diaphragm pump featuring an auxiliary or booster spring action device containing spring means which store energy from the power stroke, and release the energy to effect the return or suction stroke of the diaphragm.

Parent Case Text

This is a continuation, of application Ser. No. 123652, filed Mar. 12, 1971, now abandoned.

Description

This invention relates to diaphragm pumps and pumping systems embodying a diaphragm pump, which are well suited and operationally reliable for handling sludges and slurries, for example sewage sludges and metallurgical pulps. These are volumetrically effective displacement pumps relatively immune to wear and tear by the slurry solids, and self-priming when installed with a negative suction head, with their capacity and mode of operation readily adjustable by the adjustment of the length and/or frequency of the stroke.

Therefore the diaphragm pumps are distinct from rotary pumps such as centrifugal pumps or Moyno pumps or other rotating pumps which as a class are subject to wear and tear due to the rotation of parts, especially in an abrasive environment.

This invention relates more particularly to pressure operated diaphragm pumps as well as pumping systems embodying a diaphragm pump, wherein the pumping stroke is effected by fluid pressure admitted to the opposite side of the diaphragm while the return stroke may be effected either by gravity filling of the pump chamber, or by the application of vacuum alternating with the fluid pressure, acting upon said outer exposed side of the diaphragm. These pressure operated or non-mechanically actuated pumps again as a group are distinct from those that are known as the mechanically driven pumps wherein positive reciprocation of the diaphragm is effected by a mechanically or positively motivated actuating rod connected to the diaphragm.

Thus it will be understood that the prior pressure operated diaphragm pump comprise a pump housing divided by a free floating diaphragm into a pressure actuating chamber, and a pumping chamber. A control system including timing devices regulate the admission of the pressure fluid alone where pump filling under a positive or gravity suction head is available, or they regulate the admission of pressure fluid alternating with vacuum where the pump chamber is required to operate with a negative suction head. The fluid pressure medium may be air or water, whichever is practical under given circumstances.

The mechanically or positively actuated diaphragm pumps in turn, require nothing but a power supply for their operation, but they suffer from the disadvantage that the diaphragm due to its positive mechanical connection to a reciprocating drive, is subject to a combination of high shearing, bending, and tension stresses in the operation of the pumping cycle. These stresses are aggravated by the uncushioned reversal of the forces effective on the diaphragm at the end of the respective strokes of the pumping cycle, which in turn limits diaphragm life, and limits discharge head capability. Such stresses then lead to shutdowns and replacements of the diaphragm when destruction thereof is imminent or has occurred.

Under these conditions, maximum stresses in the diaphragm occur during the pumping stroke when the actuating rod acting like a punch upon the central portion of the diaphragm, must push against the full pumping head. Correspondingly high shearing stresses thus develop around the two clamping plates that fix the central portion of the diaphragm to the actuating rod. Lesser stresses develop during the return or pump filling stroke, for instance with the pump operating on a suction head that is a fraction of the 34 ft. maximum lift determined by the atmospheric pressure. A practical average suction lift frequently required is in the order of 10 to 12 ft., as compared with a pumping head that may be, say, ten times that much.

The diaphragm pumps of the group that are operated by fluid pressure, or else by a combination of fluid pressure and vacuum, acting upon the free floating diaphragm, are stress-compensated in the sense that they avoid the aforementioned high diaphragm stresses inherent in the mechanically actuated pumps, thereby prolonging the life of the diaphragm. However, their operation is relatively sluggish in negative suction lift applications and their capacity relatively limited due to the time-consuming character of the operating cycle which in the case of negative suction lift operation and air as the pressure medium, comprises (a) admission, build-up, and maintaining of air pressure to effect the pumping stroke, (b) venting the air pressure chamber at the end of the pumping stroke, (c) admission, build-up, and maintaining of vacuum instead of the air pressure to effect the pump-filling stroke, and (d) again venting in preparation for the next pumping cycle. This mode of operation is relatively sluggish especially in the handling of sludges of higher densities and/or viscosities, although providing cushioning effects in the operating cycle, that are lacking in the aforementioned group of mechanically actuated pumps. To this must be added the cost for providing both the fluid pressure and the vacuum.

It is a general object of this invention to provide an improved diaphragm pump that is free from the essential drawbacks of the aforementioned two groups of diaphragm pumps.

Consequently, it is among the more specific objects to provide a diaphragm pump which avoids the high diaphragm stresses of the mechanically actuated pumps; which minimizes wear and tear on the diaphragm by minimizing the diaphragm stresses throughout the pumping cycle; which overcomes the sluggishness and capacity limitations of the pressure-actuated pump, while maintaining the cushioning effects; and which is economical to operate.

Another object is to provide inexpensive means for converting a pressure-operated diaphragm pump operating under a gravity suction head into one adapted for negative suction lift operation, yet without requiring a vacuum supply.

Still another object is to provide inexpensive means for increasing the capacity of fluid pressure-actuated diaphragm pumps irrespective of whether or not they are equipped for gravity head, or negative suction head operation.

Another object is to provide a diaphragm pump of great versatility, applicable to a large spectrum of operating conditions and requirements.

In order to attain the foregoing objectives, this invention provides a diaphragm pump of the fluid pressure operated type equipped with a novel auxiliary or booster spring action device moving the diaphragm in a novel type of pumping cycle. In the operation of this pumping cycle, a spring means stores energy derived from the fluid pressure operated pumping stroke, which energy is subsequently expended in effecting, or assisting in the return stroke of the diaphragm.

Pre-tension of the spring is adjustable to suit a variety of operating requirements which may include converting the pump operation from gravity suction head to negative suction head operation, and vice versa, or else merely increasing the capacity or efficiency of the pump.

In a practical embodiment of the invention, the diaphragm is connected to an actuating rod extending through the wall of the pump housing in a direction opposite to the delivery side thereof, and perpendicular to the plane of the diaphragm. The protruding length of the actuating rod, surrounded by a compression spring, is fully enclosed in a tubular shell or casing rigidly connected to the wall of the pump housing, and in air tight sealed relationship therewith. With this spring action device in the pumping cycle, the moving force exerted upon the diaphragm is, at most, moderate or negligible thus minimizing wear and tear on the diaphragm, as will appear from the following outline of the operating cycle employing air pressure, which comprises:

1. Pumping - or Delivery Stroke:

Air pressure is admitted to the actuating pump chamber by a power starting signal from a timer, controlling a solenoid valve. The power stroke, while pumping against pump discharge head, also compresses the coil spring causing it to store energy. Air pressure is shut off by the timer at the end of the power stroke, thereby immediately releasing the stored energy of the spring, while venting the actuating chamber.

2. Suction Stroke:

The timer keeps the power shut off for the duration of a dwell period, allowing the stored energy of the spring to effect the return or suction stroke of the diaphragm, while at the same time displacing the residual air or actuating fluid from the actuating chamber.

3. At the end of the dwell period and of the suction stroke, the timer again allows air pressure to be admitted for the next pumping cycle.

The diaphragm stresses are thus minimized, since the forces acting upon the diaphragm can never exceed the maximum compression force imposed upon the spring, which in turn need only be great enough to effect the return or suction stroke.

Additional stress relieving factors are that the stroke reversal stresses are cushioned in the operation of this pumping cycle, and that the diaphragm itself is subject to flexure in only one direction, and not alternatingly between convex and concave, or between an annular valley and an annular peak.

Specific features lie in details of construction of the booster spring device.

Other features lie in the manner whereby conventional air pressure-actuated pumps can be converted into improved pumps operable in accordance with this invention.

Another feature lies in the provision of means for controlling the capacity of the pump by way of adjusting the preload on the spring of the energy-storing device.

Other features lie in timer-controlled pumping systems embodying this invention.

Other features and advantages will hereinafter appear.

Now referring to the drawings:

FIG. 1 is a vertical sectional view of the timer-controlled diaphragm pump equipped with the booster spring action device featuring an air tight encased compression spring surrounding a diaphragm actuating rod, and cooperating with an air pressure medium supply.

FIG. 1a is a fragmentary detail view showing a modification of FIG. 1.

FIG. 2 is a reduced vertical side view of the pump of FIG. 1, showing the compression spring with the casing removed.

FIG. 3 is an exploded view of the pump of FIG. 1, illustrating a conversion feature for embodying the invention in existing pumps.

FIGS. 4, 5, 6 and 7 show a pumping system illustrating an operating cycle of the pump embodying the invention.

FIG. 8 schematically illustrates diaphragm deformation and stresses in the pump embodying this invention.

FIG. 9 is a schematic view of a pump system equipped with the energy storing spring action device, operated with water as the pump actuating pressure medium.

The operation of the diaphragm pump embodying an example of this invention in FIG. 1, is controlled by the setting of one or more solenoid actuated valves, which setting in turn is governed by a timing device or timer sending power signals to the valves. The timing of the operating cycle is such that a fluid pressure medium is admitted through one of said valves to the actuating chamber of the pump at a pressure high enough to execute the pumping stroke of the diaphragm, thus delivering the contents of the pumping chamber against the pressure of the pumping head. At the end of this pumping stroke, the supply of fluid pressure medium is shut off by the timer, while a vent connection is opened to the actuating chamber, in preparation for the subsequent return -- or pump filling stroke.

According to this invention, in case there is available a negative suction head, the return stroke does not require the application of a vacuum to the pumping chamber, but is carried out effectively by a novel spring action device mounted upon the actuating chamber, and having a mechanical connection to the center of the diaphragm. The fluid pressure medium is admitted to the actuating chamber at a pressure sufficiently in excess of the pumping head, as well as in excess of the pre-tension of the spring means of the spring action device, whereby the spring means are tensioned in proportion to the length of the pumping stroke, with a corresponding amount of mechanical energy thus being stored in the spring.

When the supply of the pressure medium is shut off and the vent is opened at the end of the pumping stroke, the energy stored in the tension spring is thereby released, immediately initiating the return -- or pump filling stroke which simultaneously displaces the spent fluid pressure medium from the actuating chamber through the vent connection.

In case there is available a gravity head at the pump intake, the energy storing spring action device can be oriented towards accelerating the return stroke action, thereby increasing the capacity of the pump, especially where there is only a moderate gravity head available.

Even with vacuum supply available as in an existing timer -- controlled standard pump installation, the spring action device of this invention is advantageously applicable to aid the vacuum effect, thereby again accelerating the return stroke and increasing the pump capacity. On the other hand, in such an instance the existing vacuum supply may be dispensed with by substituting the energy storing effect of the spring action device of this invention, even though continuing the use of the existing timing and control devices governing the operating cycle of the pump.

Referring to the example embodying the invention in FIG. 1, the pump in the upright position herein shown has a circular diaphragm 10 marginally confined between an upper part or section 11 and a lower part or section 12 of a pump housing H, which parts or sections are detachably connected to each other in pressure tight relationship. The diaphragm thus divides the pump housing into a pump chamber 13 at the bottom and an actuating chamber 14 at the top. The upper housing section 11 has an opening 15 concentric with the diaphragm. The lower housing section 12 representing the pumping -- or delivery chamber has a connection 16 communicating in a usual manner (see FIG. 2) with an intake -- or suction pipe 17 through a check valve 18, as well as with a delivery pipe 19 through a check valve 20.

The upper housing section 11 has a second opening 15a provided for the purpose of admitting into the actuating chamber a fluid pressure medium usually air, but where compressed air may be unavailable, it could be a liquid such as water or it could be oil.

An actuating rod 21 connected to the center of the diaphragm extends upwardly through opening 15, a substantial distance D beyond the top of the pump housing. An elongate substantially tubular upright casing 22 provides an airtight enclosure for the upwardly protruding end portion of the actuating rod. The casing itself comprises a tubular member 23 having a top end closed by a screw cap 24, and a bottom end rigidly connected to a cup-shaped base member or nipple 25, as through a thread connection 26. This cup-shaped base member has a downwardly extending neck portion 27 which in turn is tightly threaded into the corresponding upwardly extending neck portion 28 of the pump housing. A bushing 29 inserted in the base member may provide loose guidance for the actuating rod. An annular plate 30 fitted over the bushing presents the inner bottom face 31 of the casing.

The diaphragm has a suitable connection with the actuating rod 21, whereby the central portion of the diaphragm is confined tightly between a pair of pressure plates 21a and 21b of a suitable diameter d and held in place by a cap nut 21c against a shoulder 21d formed on the actuating rod.

A compression coil spring 32 contained within the casing surrounds the actuating rod being end wise confined between said bottom face 31 of the casing and an adjustable stop means 33 provided upon the upper threaded end portion 34 of the rod. This stop means may be adjusted by using the adjustment nuts 34a and 34b, so as to impose a suitable pre-tension upon the compression spring, the amount of such pre-tension on pre-load depending upon a variety of specific conditions or technical applications of the pump, such as will be furthermore set forth below. FIG. 2 illustrates how the elongate part of the casing 22 may be removed from the base member, in order to expose the pre-tension adjusting means.

A modification of the top end portion of casing 22 comprises a screw cap 23.sup.a on tubular member 23, provided with an adjustable stop screw 23.sup.b and lock nut 23.sup.c coaxial with the actuating rod 21.

FIG. 3 is an exploded view of the pump shown in FIG. 1 above described, to illustrate the feature of convertability. This means that a sub-assembly S of parts including the energy storing spring action device above described, may take the place of the upper part or housing section of an existing timer-controlled air diaphragm pump having air pressure -- as well as vacuum supply. This sub-assembly may in fact include even the existing diaphragm which can be prepared for the purpose of conversion simply by the provision therein of a central hole for the actuating rod.

The special function and effect as well as the features and advantages of the energy storing spring action device will furthermore appear from the following description of the pump operating cycle as illustrated in FIGS. 4, 5, 6 and 7.

For this purpose it may be assumed that the pump together with its operating control system schematically shown in FIG. 4 is one that has been converted in the manner of FIG. 2 above described. In that case, the energy-storing device acts to enhance the existing vacuum effect applied to the actuating chamber during the pump filling or suction stroke, thereby accelerating the pumping action, and increasing the capacity of the pump.

The control system schematically shown comprises a pair of rotary valves V-1 and V-2 motivated by solenoid devices P 1 and P-2 respectively. These solenoid devices in turn receive power signals from a timing device or timer (not shown) in the pumping cycle described as follows:

The Pumping -- or Delivery Stroke:

To begin the pumping cycle, with a setting of the valves according to FIG. 5, and upon a power signal from the timer, compressed air from a supply pipe 35 is admitted to the actuating chamber 14 of the pump through valve port 36 of valve V-1 and pipe connection 37. The air pressure moves the diaphragm in a pumping stroke from an upper limit position to a lower limit position, thereby delivering the content of the pumping chamber 13 against the existing pumping head. The air pressure thus applied through valve V-1 is in excess of that required by the pumping stroke, the excess being sufficient to compress the coil spring 32, as well as to overcome an amount of pre-tension imposed upon the spring by the setting of the stop means 33. The position of valve V-1 during this stroke closes an intermediate pipe connection 38 extending between valve V-2 and valve V-1, while valve V-2 has an exhaust connection 39 communicating through valve port 40 with the intermediate pipe 38.

The Suction - or Pump Filling Stroke:

At the end of the pumping stroke, a power signal from the timer moves the valve V-1 to the FIG. 6 position, thus shutting off the air pressure supply while valve V-2 remains unchanged, thus briefly establishing an exhaust or vent connection through valve V-2, which equalizes the pressure in the actuating chamber with that of the atmosphere. The timer thereupon sends a power signal moving the valve V-2 to the FIG. 7 position, while the position of valve V-1 remains unchanged, thereby establishing a connection between the actuating chamber 14 and a vacuum supply pipe 41 by way of port 40 of valve V-2. The suction -- or pump filling stroke is initiated immediately upon shutting of the air supply, due to the release thereby of the energy stored in the spring during the pumping stroke. This energy is now expended to sustain the suction stroke, aided by the vacuum supply, while simultaneously effecting the evacuation of the actuating chamber. At the end of this suction -- or pump filling stroke, the timer sends power signals for resetting valves V-1 and V-2 to the initial FIG. 5 position.

It will be understood, however, that the vacuum supply phase can be omitted from the pumping cycle just described of FIGS. 4 to 7, simply by omitting the valve V-2 and its accessories, and venting the actuating chamber of the pump directly from valve V-1, and further by a suitable resetting of the pretension of the spring.

The schematic showing of a timer-controlled pump system in FIG. 9 differs from the one shown in FIG. 4, due to the fact that a liquid is employed as the pump actuating fluid pressure medium instead of air. Therefore, a diaphragm pump 45 structurally and functionally corresponding to that of FIG. 1, is connected to a pressure supply system which comprises a closed pressurized storage -- or buffer bank 46 which has therein an air pressure cushion 46.sup.a maintainable, if need be, through a check valve 45.sup.b similar to an automobile tire valve or the like. A pump 47 continuously supplies water or other suitable liquid such as oil from a reservoir 48 which is open to the atmosphere.

In the operating cycle of this system, a solenoid-controlled valve V-3 having received a power signal from a timer (not shown), is set with the port 49 allowing liquid from the pressurized tank 46 to be forced into the actuating chamber 50 of the pump, moving diaphragm 51 downwardly against the pumping head while simultaneously through actuating rod 52 compressing the spring 53 of the energy-storing device. At the end of this pump delivery stroke, the timer will send a power signal to the valve V-3, causing the port 49 (see dotted line position) to interrupt the supply of the pressure liquid, while establishing a flow -- or vent connection with the actuating chamber. This immediately releases the energy stored in the previously compressed spring, effecting the upward return - or pump filling stroke that displaces the spent liquid from the actuating chamber back into the reservoir 48, whereupon the cycle repeats itself.

From the foregoing it will be seen that the actuating rod is subjected to pull and not to compression throughout the pumping cycle. On that basis, it is also seen, from the schematic illustration in FIG. 8, that in a pump 54 structurally and functionally corresponding to that of FIG. 1, the flexure of the diaphragm occurs substantially in only one direction throughout the pumping cycle, thereby reducing wear and tear on the diaphragm. Therefore, the three positions A, B and C of the diaphragm shown in FIG. 8, represent the respective flexures that manifest themselves during the delivery stroke as well as during the suction -- or pump filling stroke. The flexures A and B represent the end condition, and flexure C an intermediate condition of the diaphragm, with the actuating rod 55 and the spring 56 acting in the manner previously described.

In connection with these flexures, it should be understood that the diaphragm in its downward movement under pressure from the fluid medium admitted through a connection 57 hugs the bottom of the pumping chamber progressively from the periphery towards the center, although this condition does not appear fully in FIG. 8 due to the schematic character thereof. Therefore, the diaphragm in its downward movement under fluid pressure, evenly displaces pulp or slurry progressively inwardly towards the outlet connection 44 of the pumping chamber, which avoids trapping of material between the diaphragm and the pump housing.

This invention provides means for adjusting the pump capacity by way of setting the pre-load on the spring of the energy-storing device, by adjusting the position of the stop means 33 on the actuating rod. Such adjustments are described as follows:

Capacity Control through Spring Preload Adjustment:

Maximum pumping capacity is achieved by imposing maximum preload upon the spring, that is without exceeding the design limit or capability of the spring when it reaches its maximum compression at the bottom end of the pumping -- or delivery stroke. When a reduction below maximum is required, this is obtainable by a corresponding reduction in the preload on the spring by using the adjustment nuts in stop device 33 (see FIG. 1).

Under negative suction lift conditions, the length of the suction stroke is determined by the amount of preload imposed upon the spring, the preload required being proportional to the amount of suction lift. That is to say, the minimum amount of spring compression force that will pull the diaphragm to the desired top limit in the actuating chamber 13 of the pump, is the minimum preload FM required to provide full volumetric pump capacity per stroke. A preload on the spring of less than FM and designated as FR, reduces the length of the stroke, thereby reducing the capacity per pumping cycle.

During the pumping stroke, an additional compressive force FS is imposed upon the spring, which is in excess of the preload FM that exists at the upper limit or beginning of the stroke. This additional force FS creates the vacuum which moves and accelerates the fluid mass into the lower pump chamber 14 on the suction stroke. Increasing the preload force FM by an amount FA produces a corresponding increase in the amount of force available for said mass acceleration, thereby increasing the pump filling rate. These conditions are summarized in the following tabulation.

TABULATION ______________________________________ TOTAL SPRING COMPRESSION FORCE AT END OF PUMPING STROKE MODE OF OPERATION EFFECT ON PUMP CAPACITY *DIAPHRAGM STRESSES FOR BOTH SUCTION & DISCHARGE STROKES ______________________________________ FM+FS Full suction stroke (average acceleration) Average capacity Nominal FM+FS+FA Full suction stroke (Increased Acceleration) Above average capacity Slightly above nominal FR+FS Partial suction stroke Below average capacity Below nominal ______________________________________ *With diaphragm flexure occurring substantially in only one direction throughout the pumping cycle, thereby reducing wear and tear on the diaphragm.

In addition to capacity adjustment with the timer, and the spring preload adjustment discussed above, there is available a third variable control factor affecting the capability of the pump, namely the amount of fluid pressure applied in the actuating chamber 13 of the pump. That is to say, the higher the pressure, the greater becomes the capacity. If the fluid pressure is reduced below an amount that will neutralize the force FM + FS, such a reduction will cause the pump to operate at a shorter stroke, thereby reducing the overall capacity of the pump.

By manipulating the control factors, namely Timing, Spring Preload, and fluid pressure, singly or in combination, the pump capacity can be varied within the limits of capability of the pump. Also, with these control factors available, the stroke can be shortened, and frequency increased, thus dampening out the pulse effect, and producing a more continuous flow from the pump, when the technical application of the pump requires that the amplitude of the pump pulses should be minimized.

As this invention may be embodied in several forms without departing from the spirit or essential character thereof, the present embodiment is illustrative and not restrictive. The scope of the invention is defined by the appended claims rather than by the description preceding them, and all embodiments which fall within the meaning and range of equivalency of the claims are, therefore, intended to be embraced by those claims.

Claims

I claim:

1. A pumping system which comprises a diaphragm pump having a pump housing, a diaphragm dividing the housing into a pumping chamber having means for pump discharge and for pump intake, and a pump actuating chamber having an opening substantially concentric with said diaphragm, said actuating chamber adapted to receive a fluid pressure medium acting upon the diaphragm to produce the pumping stroke, and also adapted to be vented during a dwell period following said pumping stroke during which period the fluid pressure supply is interrupted to allow for the pump filling return stroke of the diaphragm,

an actuating rod extending from said diaphragm through said opening, so that a major portion of its length is outwardly exposed of the pumping chamber,

a compression coil spring encircling said exposed length of rod, confined between said opening in the pump chamber and an adjustable stop means provided upon the outer end portion of said rod, said stop means being operable to adjust the preload tension upon the spring, and thus the energy storing capacity thereof, effective to retract the diaphragm during said pump filling stroke,

a casing surrounding the exposed length of the rod, rigidly connected to said opening in pressure-sealed connection therewith, and having a disconnectible portion to allow for access to said stop means for adjusting the preload tension of the spring,

said casing comprises a tubular member coextensive and concentric with said actuating rod, and a hollow base member coaxial with said tubular member, one end of said base member having threaded connection with the inner end of said tubular member, the other end of said base member having threaded connection with said opening in the housing, and

control means apart from said casing and said pump housing for governing the pumping cycle, which comprise time controlled valve means operable from the timer between one valve position which connects the actuating chamber with a fluid pressure supply for the duration of the pumping stroke, said supply providing a pressure high enough to effect the pumping stroke while also overcoming the resistance of the spring in storing energy therein, and another valve position which interrupts the pressure supply, while connecting the pumping chamber to exhaust, and allowing said spring energy to effect the suction stroke while expelling spent fluid medium from said actuating chamber.

2. In a single acting pressure fluid actuated diaphragm pump, the combination which comprises a flanged pump housing member of dished configuration, provided with a central opening,

a diaphragm facing the hollow of said housing member, concentric with said central opening, and constituting with said housing member a pump actuating chamber,

an actuating rod extending from the center of said diaphragm through said central opening, so that a major portion of its length is outwardly exposed of said housing,

a compression coil spring encircling said exposed length of the rod, and confined between said central opening and adjustable stop means provided on the outer end portion of said rod, said stop means being operable to adjust a preload tension upon said spring,

a casing surrounding said exposed length of the rod and comprising a tubular member coextensive and concentric with said actuating rod,

means rigidly connecting said casing to said opening in pressure-sealed relationship therewith, said connecting means including a hollow base member coaxial with said tubular casing and having one end in threaded connection with an inner end of said tubular casing and the other end of said base member having a threaded connection with said housing, at said central opening therein, and

said opposite end of said tubular casing having a disconnectible portion to allow for access to said stop means for adjusting the same to vary a preload tension of the spring.

3. A pumping system which comprises a diaphragm pump having a pump housing, a diaphragm dividing the housing into a pumping chamber having means for pump discharge and for pump intake, and a pump actuating chamber having an opening substantially concentric with said diaphragm, said actuating chamber adapted to receive a fluid pressure medium acting upon the diaphragm to produce the pumping stroke, and also adapted to be vented during a dwell period following said pumping stroke, during which period the fluid pressure supply is interrupted to allow for the pump filling return stroke of the diaphragm, a casing extending rigidly outwardly from said opening in pressure-sealed relationship therewith, and an energy storing spring action device contained in said casing, and cooperatively associated with said diaphragm through said opening, and constructed and arranged so as to store energy derived from the pumping stroke, and thereafter during said dwell period to allow said stored energy to be expended to exert a pull upon the diaphragm during said return stroke thereof, means for adjusting the preload on the spring in said spring action device,

and control means governing the pumping cycle for pressure fluid supply during the pumping stroke and vacuum supply during the suction stroke, which control means comprise a first valve position which connects the actuating chamber with a fluid pressure supply for the duration of the pumping stroke, said supply providing a pressure high enough to effect the pumping stroke while also overcoming the resistance of the spring in storing energy therein, and a second valve position which interrupts the pressure supply, while connecting the pumping chamber to a transfer conduit, and a second timer-controlled valve means interconnected with said first valve through said transfer conduit, and operable from the timer to establish one valve position which connects said transfer conduit to exhaust incident to said second valve position of the first valve, and to establish another position incident to said second valve position of said first valve, connecting the actuating chamber to a vacuum supply for the duration of the return suction stroke.

4. A pumping system which comprises a diaphragm pump having a pump housing, a diaphragm dividing the housing into a pumping chamber having means for pump discharge and for pump intake, and a pump actuating chamber having an opening substantially concentric with said diaphragm, said actuating chamber adapted to receive a fluid pressure medium acting upon the diaphragm to produce the pumping stroke, and also adapted to be vented during a dwell period following said pumping stroke, during which period the fluid pressure supply is interrupted to allow for the pump filling return stroke of the diaphragm, a casing extending rigidly outwardly from said opening in pressure-sealed relationship therewith, and an energy storing spring action device contained in said casing, and cooperatively associated with said diaphragm through said opening, and constructed and arranged so as to store energy derived from the pumping stroke, and thereafter during said dwell period to allow said stored energy to be expended to exert a pull upon the diaphragm during said return stroke thereof, and means for adjusting the preload on the spring in said spring action device,

and control means governing the pumping cycle, which comprise a closed pressurized storage and buffer tank, containing a body of a liquid pressure medium, a reservoir open to the atmosphere containing another body of said liquid pressure medium, a pump for continuously supplying said liquid medium to said pressurized tank,

and a timer-controlled valve operable from the timer between one valve position connecting the actuating chamber of the pump with pressurized tank, to allow the pressure in said tank to effect the pumping stroke, and another valve position connecting said actuating chamber with air exhaust delivery conduit during the return suction effected by the stored spring energy, said conduit delivering the spent liquid into said reservoir.