# Patent

## Title
Air-driven pump system

## Abstract

An air-driven pump system comprising an efficiency valve. One or multiple efficiency valves integral to the pumping system prevent overfilling of the air chambers, thereby reducing the amount of air used by the system while decreasing the energy wasted by the system.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority to U.S. Provisional Patent Application No. 61/341,160, filed on Mar. 29, 2010, and entitled “Air-Driven Fluid Pump System,” the content of which is relied upon and incorporated herein by reference in its entirety.


BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pneumatically-driven equipment, and, more specifically, to an efficiency valve in that equipment.
2. Description of the Related Art
Pneumatically driven equipment typically relies on mechanically moving parts to operate. The equipment will typically split the inlet motive air into process air and control air, in which the process air is used to perform the work and the control air is used to control the direction or motion of the mechanical components.
However, there is an inherent inefficiency that occurs in such air-driven equipment. The inefficiency is related to the reaction time or response time of the mechanical components as compared to the flow rate of both the process air and control air. In other words, the flow rate of the motive air far exceeds the velocity of the mechanical components because of friction losses and other dynamic losses acting on the mechanical components, created by the movement of the mechanical components. The inefficiency occurs when motive air is wasted by allowing it to continuously flow un-restricted into the pneumatic equipment when the process air has completed a first segment of work and the control air is mechanically moving components to a position that allows the process air to perform a second segment of work.
An example of this inefficiency is illustrated in FIGS. 1-3, which depict a schematic representation of an air-operated piston pump having a general design. In FIG. 1, inlet motive air is split into process air and control air. Control air positions the directional valve piston 11 inside directional valve 10 by filling chambers 12. Control air is also channeled out of chamber 12 and directional valve 10 and into pilot valve 40, and is then directed through pilot valve piston 41 to be channeled back to directional valve 10, thereby pressurizing chamber 13 in directional valve 10. Although the control pressure is equal for both chambers 12 and 13, the surface area of piston 11 on which the control pressure is acting is greater in chamber 13, causing piston 11 to move and remain to the “left” in directional valve 10. This allows the process air to pass through directional valve 10 and directional valve piston 11 and then be channeled to pump unit 30, thereby expanding into air chamber 32, acting on piston 31, and moving piston 31 to discharge liquid from liquid chamber 33. At the same time, movement of piston 31 toward the right pulls shaft 54, thereby moving piston 21 inside pump unit 20. Movement of piston 21 toward the other pump unit causes liquid to be drawn into liquid chamber 23 as once-used process air is released from air chamber 22 out of pump unit 20 and channeled through directional valve 10 and directional valve piston 11 to atmosphere.
In FIG. 2, piston 21 engages and moves shaft 64, which is connected to pilot valve piston 41 inside of pilot valve 40. Movement of piston 21 moves shaft 64 and pilot valve piston 41 to a position that allows channeled control air to be released to atmosphere from chamber 13 inside directional valve 10. Control air pressure in chamber 12 acts on directional valve piston 11, moving directional valve piston 11 toward the right inside directional valve 10.
In FIG. 3, directional valve piston 11 in directional valve 10 is held stationary by the control air pressure in chamber 12 acting on directional valve piston 11, thereby allowing process air to be channeled through directional valve 10 and directional valve piston 11 to pump unit 20, where it expands into air chamber 22 as once used process air is released from air chamber 32 in pump unit 30. The process air is further channeled through directional valve 10 and directional valve piston 11 to atmosphere, making pistons 21 and 31 and shaft 54 reverse their previous directions, thereby causing piston 21 to force liquid from liquid chamber 23 to discharge as piston 31 draws liquid into liquid chamber 33.
The inefficiency with the above-described design occurs during the transition from FIG. 2 to FIG. 3. During the total time period that it takes moving pilot valve piston 41 in pilot valve 40 to move to a position that re-directs control air to or from directional valve 10 and directional valve piston 11 moves completely to its new position to allow process air to perform a new segment of work (from “left” in FIG. 2 to “right” in FIG. 3), process air is allowed to continue entering the air chamber (air chamber 32 in FIG. 2) unrestricted, which overfills or over pressurizes the air chamber without additional liquid being discharged from it corresponding liquid chamber (liquid chamber 33 in FIG. 2). This overfilling or over pressurizing of the air chamber is a waste of energy.
There is, therefore, a continued need for pneumatically driven equipment such as air-driven liquid pumps that are more efficient and utilize less energy than previous designs.
BRIEF SUMMARY OF THE INVENTION
It is therefore a principal object and advantage of the present invention to provide a more efficient pneumatically driven pump.
It is another object and advantage of the present invention to provide a pneumatically driven pump that utilizes less air for pumping.
It is yet another object and advantage of the present invention to provide a pneumatically driven pump that utilizes less energy.
Other objects and advantages of the present invention will in part be obvious, and in part appear hereinafter.
In accordance with the foregoing objects and advantages, the present invention provides an air-driven piston pump comprising: (i) a directional unit that defines a directional air chamber and comprises a directional piston, a first process air intake, and a second process air intake; (ii) a first pump unit comprising a first liquid chamber, a first air chamber, and a first piston, where the first piston is located inside the first pump unit between the first liquid chamber and the first air chamber, and the first piston moves between a first position and a second position; (iii) a second pump unit comprising a second liquid chamber, a second air chamber, and a second piston, where the second piston is located inside the second pump unit between the second liquid chamber and the second air chamber, and the second piston is moveable between a first position and a second position; (iv) a first shaft affixed at one first end to the first piston and affixed at the other end to the second piston; (v) an efficiency unit comprising an efficiency piston, wherein the efficiency unit is configured to divide inlet air entering the air-driven piston pump into control air, first process air, and second process air, and wherein the efficiency piston is in communication with the control air, first process air, and second process air before the air is distributed to the directional unit; (vi) a second shaft which is in communication with the efficiency piston. In a preferred embodiment, the efficiency piston is moveable between a first position and a second position, where the first position allows control air to communicate with the directional unit air chamber, allows first process air to distribute to the first process air intake of the directional unit, and restricts second process air, thereby allowing restricted second process air to distribute to the second process air intake of the directional unit. In the second position, the efficiency piston allows control air to communicate with the directional valve air chamber, allows second process air to distribute to the second process air intake of the directional unit, and restricts first process air, thereby allowing restricted first process air to distribute to the first process air intake. The efficiency piston is preferably affixed to the second shaft at some location along the length of the second shaft.
According to a second aspect of the present invention, the second shaft comprises a first end and a second end. The first end is located at least partially within the first pump unit and is positioned to communicate with the first piston when the first piston is in the second position. The second end is located at least partially within the second pump unit and is positioned to communicate with the second piston when the second piston is in the second position. In a preferred embodiment, when the first end of the second shaft is in communication with the first piston, the efficiency piston moves to the second position, and when the second end of the second shaft is in communication with the second piston, the efficiency piston moves to the first position.
According to a third aspect of the present invention is provided an air-driven piston pump comprising: (i) a directional unit which defines a directional air chamber and comprises a directional piston, a first process air intake, and a second process air intake; (ii) a first pump unit comprising a first liquid chamber, a first air chamber, and a first piston, the first piston located inside the first pump unit between the first liquid chamber and the first air chamber and moveable between a first position and a second position; (iii) a second pump unit, the second pump unit comprising a second liquid chamber, a second air chamber, and a second piston, the second piston located inside the second pump unit between the second liquid chamber and the second air chamber and moveable between a first position and a second position; (iv) a first shaft affixed at a first end to the first piston and affixed at a second end to the second piston; (v) a first efficiency unit comprising a first process air inlet, a first process air outlet, and a first efficiency piston comprising a first efficiency piston shaft, where the first efficiency piston is moveable between a first position and a second position; (vi) a second efficiency unit comprising a second process air inlet, a second process air outlet, and a second efficiency piston comprising a second efficiency piston shaft, where the second efficiency piston is moveable between a first position and a second position; (vii) a pilot unit comprising a pilot piston, where the pilot piston is moveable to at least a first position and a second position; and (viii) a second shaft which is in communication with the pilot piston.
According to a fourth aspect of the present invention, the second shaft of the above-described pump comprises a first end and a second end. The first end is located at least partially within the first pump unit and is positioned to communicate with the first piston when the first piston is in the second position. The second end of the second shaft is located at least partially within the second pump unit and is positioned to communicate with the second piston when the second piston is in the second position. In a preferred embodiment, when the first end of the second shaft is in communication with the first piston, the pilot piston moves to the second position, and when the second end of the second shaft is in communication with the second piston, the pilot piston moves to the first position.
According to a fifth aspect of the present invention, at least a portion of the first efficiency piston shaft is located within the first pump unit and is positioned to communicate with the first piston when the first piston is in the second position. At least a portion of the second efficiency piston shaft is located within the second pump unit and is positioned to communicate with the second piston when the second piston is in the second position. Further, when the first efficiency piston shaft communicates with the first piston, the first efficiency piston moves to the second position and restricts the distribution of air through the first efficiency unit to the first process air intake of the directional unit. When the second efficiency piston shaft communicates with the second piston, the second efficiency piston moves to the second position and restricts the distribution of air through the second efficiency unit to the second process air intake of the directional unit. When the first efficiency piston shaft is no longer in communication with the first piston, the first efficiency piston moves to the first position and allows, or un-restricts, the full distribution of first process air through the first efficiency unit to the first process air intake of the directional unit. When the second efficiency piston shaft is no longer in communication with the second piston, the second efficiency piston moves to the first position and allows, or un-restricts, the full distribution of second process air through the second efficiency unit to the second process air intake of the directional unit.
According to a sixth aspect of the present invention is provided an air-driven piston pump comprising: (i) a directional unit defining a directional air chamber and comprising a directional piston, a first process air intake, and a second process air intake, the directional piston moveable between a first position and a second position; (ii) a first stage pump unit, the first stage pump unit defining a first stage air chamber; (iii) a first pump unit, the first pump unit comprising a first liquid chamber, a first second stage air chamber, and a first piston, where the first piston is located inside the first pump unit between the first liquid chamber and the first second stage air chamber and is moveable between a first position and a second position; (iv) a second pump unit, the second pump unit comprising a second liquid chamber, a second second stage air chamber, and a second piston, where the second piston is located inside the second pump unit between the second liquid chamber and the second second stage air chamber and is moveable between a first position and a second position; (v) a first shaft affixed at a first end to the first piston and affixed at a second end to the second piston; (vi) a first stage piston located inside the first stage air chamber and affixed to the first shaft, wherein the first stage piston and the first shaft are moveable from a first position to a second position; (vii) a first efficiency unit comprising a first control air port, a first air inlet, a first process air outlet, and a first efficiency piston comprising a control air channel and a first efficiency piston shaft, where the first efficiency piston is moveable between a first position and a second position; and (viii) a second efficiency unit comprising a control air port, a second air inlet, a second process air outlet, and a second efficiency piston comprising a control air channel and a second efficiency piston shaft, where the second piston is moveable between a first position and a second position.
According to a seventh aspect of the present invention, at least a portion of the first efficiency piston shaft is located within the first pump unit and is positioned to communicate with the first piston when the first piston is in the second position. Similarly, at least a portion of the second efficiency piston shaft is located within the second pump unit and is positioned to communicate with the second piston when the second piston is in the second position. In a preferred embodiment, when the first efficiency piston shaft communicates with the first piston, the first efficiency piston moves to the second position and restricts the distribution of first process air through the first efficiency unit to the first process air intake of the directional unit, and allows control air to communicate between the directional air chamber and first air chamber. Similarly, when the second efficiency piston shaft communicates with the second piston, the second efficiency piston moves to the second position and restricts the flow of second process air through the second efficiency unit to the second process air intake of the directional unit, and allows control air to communicate between the directional air chamber and the second air chamber. When the first efficiency piston shaft is no longer in communication with the first piston, the first efficiency piston moves to the first position and allows, or un-restricts, the full distribution of first process air through the first efficiency unit to the first process air intake of the directional unit and allows control air to communicate with the directional air chamber. When the second efficiency piston shaft is no longer in communication with the second piston, the second efficiency piston moves to the first position and allows, or un-restricts, the full distribution of second process air through the second efficiency unit to the second process air intake of the directional unit and allows control air to communicate with the directional air chamber.



BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
The present invention will be more fully understood and appreciated by reading the following Detailed Description in conjunction with the accompanying schematic drawings, in which:
FIGS. 1-3 represent an air-driven expansible chamber pump system of the prior art.
FIGS. 4, 4A, 5-6 represent an air-driven expansible chamber pump system of this invention with FIG. 4A representing a detail of the efficiency valve thereof.
FIGS. 7-8, 8A-9 represent an air-driven expansible chamber pump system of this invention with FIG. 8A representing a detail of the left efficiency valve thereof.
FIGS. 10, 10A-13 represent an air-driven expansible chamber pump system of this invention with FIG. 10A representing a detail of the left efficiency valve thereof.



DETAILED DESCRIPTION OF THE INVENTION
Referring now to the drawings, wherein like reference numerals refer to like parts throughout, there is seen in FIGS. 4-13 several air-driven pump systems according to embodiments of the present invention. Each air-driven pump system comprises an efficiency valve that allows pneumatic equipment to significantly reduce the energy waste associated with overfilling or over pressurizing during operation, as compared to prior art designs.
The pump systems described herein have a multitude of different uses and utilities. For example, the pump systems described herein and claimed below can be used to pump a wide variety of liquids. In addition to liquids, the pump systems can pump any gas capable of being pumped, including air. Any reference to a “liquid” pump system should be construed to mean a pump system capable of pumping a liquid and/or a gas.
It should be noted that while the Examples described herein refer to several different elements as a “piston,” these elements could also be a diaphragm component in other embodiments of the present invention. A diaphragm component would typically comprise a central diaphragm with a piston element located on either or both sides which perform(s) the functions of the pistons described in the Examples below. Further, it should be noted that in a preferred embodiment, each of the pistons described herein comprise a perimeter seal such as an o-ring or a sleeve to prevent leakage, although any mechanism of preventing leaking known in the art could be used.
EXAMPLE 1
The air-driven pump system described in Example 1 is shown in FIGS. 4-6. Starting with FIG. 4, inlet motive air enters the pneumatic pump. A small portion of the motive air is used as control air and is channeled to directional valve 210, thereby pressurizing chamber 212 to act on the small surface area of directional valve piston 211 inside directional valve 210. The balance of the inlet motive air enters efficiency valve 240 and is segmented into control air, left process air and right process. Control air passes through efficiency valve piston 241 and exits efficiency valve 240 and is channeled to pressurize chamber 213 in directional valve 210 acting on the large surface area of directional valve piston 211 inside directional valve 210, moving and holding directional valve piston 211 to the left inside directional valve 210. Left process air passes through efficiency valve piston 241 inside efficiency valve 240, unrestricted in its flow rate. Right process air passes around efficiency valve piston 241 inside efficiency valve 240, maximally restricted in its flow rate. Both left and right process air are channeled to directional valve 210. Directional valve piston 211 inside directional valve 210 blocks maximally restricted right process air and allows unrestricted left process air to pass through and exit directional valve 210 and be channeled to pump unit 230 where it expands and pressurizes air chamber 232 causing piston 231 to displace liquid from liquid chamber 233. At the same time, shaft 254 being connected to pistons 231 and 221 moves piston 221, inside pump unit 220, drawing liquid into liquid chamber 223 as once used process air is released from air chamber 222 out of pump unit 220 and channeled through directional valve 210 and directional valve piston 211 to atmosphere.
In FIG. 5, toward the end of its stroke, piston 221 in pump unit 220 engages and moves shaft 264 which is connected to efficiency valve piston 241 inside of efficiency valve 240. The movement of efficiency valve piston 241 un-restricts the exiting right process air out of efficiency valve 240 and maximally restricts the left process air flow rate out of efficiency valve 240. As such, the groove 266 in the efficiency valve piston 241 and the ports 268, 270 through the cylinder of the efficiency valve 240 to the directional valve chamber 213 and to control air out, respectively, define the pilot valve system in this embodiment.
In FIG. 6, efficiency valve piston 241 is moved to a position that allows channeled control air to be released to atmosphere from chamber 213 inside of directional valve 210. Control air pressure in chamber 212 of directional valve 210, acts on and moves directional valve piston 211 to the “right” inside of directional valve 210. During the movement of directional valve piston 211, maximally restricted left process air continues to flow at its maximally restricted flow rate through directional valve 210 and directional valve piston 211 channeled to air chamber 232 of pump unit 230, reducing over filling or over pressurizing of air chamber 232. Directional valve piston 211 is held stationary to the right inside directional valve 210 by the control air pressure in chamber 212. Maximally restricted left process air exiting efficiency valve 240 is channeled to directional valve 210 and blocked by directional valve piston 211. Unrestricted right process air exiting efficiency valve 240 is channeled through directional valve 210 and directional valve piston 211 to pump unit 220, expanding into air chamber 222 as once used process air is channeled to atmosphere from air chamber 232 out of pump unit 230 and through directional valve 210 and directional valve piston 211. Pistons 221, 231 and shaft 254 reverse their directions. Unrestricted right process air acts on piston 221 in pump unit 220 to discharge liquid from liquid chamber 223 as piston 231 in pump unit 230 draws liquid into liquid chamber 233.
EXAMPLE 2
The air-driven pump system described in Example 2 is shown in FIGS. 7-9. Starting with FIG. 7, inlet motive air enters the pneumatic pump. A small portion of the motive air is used as control air and is channeled to directional valve 510, pressurizing chamber 512 acting on the small surface area of directional valve piston 511 inside directional valve 510. Also, control air is channeled out of chamber 512 and directional valve 510 and enters pilot valve 540, passes through pilot valve piston 541 and is channeled back to directional valve 510 where it pressurizes chamber 513 acting on the large surface area of directional valve piston 511, moving and holding directional valve piston 511 to the left inside directional valve 510. The balance of the inlet motive is segmented into left and right process air. Left process air enters efficiency valves 570, passes around efficiency valve piston 571 and exits efficiency valve 570 unrestricted in its flow. Right process air enters efficiency valves 580, passes around efficiency valve piston 581 and exits efficiency valve 580 maximally restricted in its flow. Both unrestricted left process air and maximally restricted right process air are channeled to directional valve 510. Directional valve piston 511 inside directional valve 510 blocks maximally restricted right process air and passes through unrestricted left process air. Unrestricted left process air exits directional valve 510 and is channeled to pump unit 530 where it expands and pressurize air chamber 532 causing piston 531 to displace liquid from liquid chamber 533. At the same time, shaft 554 being connected to pistons 531 and 521 moves piston 521 inside pump unit 520, drawing liquid into liquid chamber 523 as once used process air is released from air chamber 522 out of pump unit 520 and channeled through directional valve 510 and directional valve piston 511 to atmosphere.
In FIG. 8, toward the end of its stroke, piston 521 in pump unit 520 engages and moves efficiency valve piston 571 in efficiency valve 570. Efficiency valve piston 571 moves to a position that maximally restricts left process air flow rate out of efficiency valve 570. The maximally restricted left process air continues to be channeled to directional valve 510. Right process air moves efficiency valve piston 581 inside efficiency valve 580, allowing right process air to exit efficiency valve 580 unrestricted and continues to be channeled to directional valve 510. Piston 521 in pump unit 520 also engages and move shaft 564 which is connected to pilot valve piston 541 inside of pilot valve 540.
In FIG. 9, the pilot valve system with pilot valve piston 541 in pilot valve 540 is moved to a position that allows channeled control air to be released to atmosphere from chamber 513 inside of directional valve 510. Control air pressure in chamber 512, moves directional valve piston 511 to the “right” inside of directional valve 510. During the movement of directional valve piston 511, maximally restricted left process air continues to flow at its maximally restricted flow rate channeled into air chamber 532 of pump unit 530, reducing over filling or over pressurizing of air chamber 532. Directional valve piston 511 is held stationary to the right inside directional valve 510 by the control air pressure in chamber 512 of directional valve 510. Maximally restricted left process air exiting efficiency valve 570 is channeled to directional valve 510 and blocked by directional valve piston 511. Unrestricted right process air exiting efficiency valve 580 is channeled through directional valve 510 and directional valve piston 511 to pump unit 520, expanding into air chamber 522 as once used process air is channeled to atmosphere from air chamber 532 out of pump unit 530 and through directional valve 510 and directional valve piston 511. Pistons 521, 531 and shaft 554 reverse their directions. Unrestricted right process air acts on piston 521 in pump unit 520 to discharge liquid from liquid chamber 523 as piston 531 in pump unit 530 draws liquid into liquid chamber 533.
While this example refers to an embodiment with two efficiency units, one for left process air and the other for right process air, an alternative single efficiency unit embodiment could process both left and right process air inclusive. Such an embodiment would, therefore, combine certain elements of, for example, FIGS. 4 and 7.
EXAMPLE 3
The air-driven pump system described in Example 3 is shown in FIGS. 10-13. Starting with FIG. 10, inlet motive air enters the pneumatic pump. The inlet motive air enters both efficiency valves 440, 460 and is segmented into control air, left process air and right process air by efficiency valve piston 441, 461 respectively. Inlet motive air passes through restrictive orifice 462 inside efficiency valve piston 461 and control air exits efficiency valve 460 through port 463 and is channeled to directional valve 410 where it enters and pressurizes chamber 412 acting on the directional valve piston 411. Simultaneously, lower pressure once used left control air from second stage air chamber 422 in pump unit 420 enters efficiency valve 440 and passes around efficiency valve piston 441 exiting efficiency valve 440 through port 443 and is channeled to directional valve 410 where it enters and pressurizes chamber 413 acting on directional valve piston 411, allowing directional valve piston to move and be held to the left in directional valve 410. Left process air passes around efficiency valve piston 441, maximally restricted in its flow rate. Right process air passes through efficiency valve 460, unrestricted in its flow rate by efficiency valve piston 461. Both left and right process air are channeled to directional valve 410 from their respective efficiency valves 440, 460. Directional valve piston 411 positioned to the left in directional valve 410, blocks maximally restricted left process air and allows unrestricted right process air to pass through and exit directional valve 410. Unrestricted right process air is then channeled to first stage pump unit 470 where it expands and pressurize first stage air chamber 473 acting on piston 471. Pistons 471, 421 and 431 are conjoined by shaft 454. Once used fixed volume left process air in first stage air chamber 472 of first stage pump unit 470 exits first stage pump unit 470 and is channeled through directional valve 410 and directional valve piston 411 to pump unit 420 where it expands into and pressurizes larger volume second stage air chamber 422 to a lower pressure acting on piston 421. Both second stage air chamber 422 and first stage air chamber 472 are at equal lower pressures. Simultaneously, twice used right process air is released from second stage air chamber 432 out of pump unit 430 and channeled through directional valve 410 to atmosphere. The combined air pressure forces acting on pistons 471, 421 and 431, all conjoined by shaft 454, moves piston 471, 421 and 431 in a direction that displaces liquid from liquid chamber 423 in pump unit 420 and draws liquid into liquid chamber 433 in pump unit 430.
In FIG. 11, inlet motive air moves efficiency valve piston 441 in efficiency valve 440 allowing left process air to exit efficiency valve 440 unrestricted in its flow as it is channeled to directional valve 410 where it continues to be blocked by directional valve piston 411 in directional valve 410. Inlet motive air passes through restrictive orifice 442 inside efficiency valve piston 441 and control air exits efficiency valve 440 through port 443 and is channeled to directional valve 410 where it continues to pressurize chamber 413 inside directional valve 410. Inlet motive air passes through restrictive orifice 462 inside efficiency valve piston 461 and control air exits efficiency valve 460 through port 463 and is channeled to directional valve 410 where it continues to pressurize chamber 412 inside directional valve 410. Both chambers 412, 413 in directional valve 410 are at equal pressures acting on directional valve piston 411 continuing to hold directional valve piston 411 to the left inside of directional valve 410. Towards the end of its stroke, piston 431 in pump unit 430 engages and moves efficiency valve piston 461 inside efficiency valve 460. Efficiency valve piston 461 in efficiency valve 460 is moved to a position that maximally restricts right process air flow rate out of efficiency valve 460 as it is channeled to directional valve 410.
In FIG. 12, efficiency valve piston 461 in efficiency valve 460 is moved with annular seal 464 traversing port 463 to a position that redirects and releases channeled control air from chamber 412 in directional valve 410 through second stage air chamber 432 in pump unit 430 coupling with residual twice used right process air and then channeled through directional valve 410 to atmosphere.
In FIG. 13, the combined control air pressure forces in chambers 412 and 413 of directional valve 410 have acted on and moved directional valve piston 411 to the right inside of directional vale 410 from the valve position of FIG. 12. During the movement of directional valve piston 411, maximally restricted right process air continues to flow at its maximally restricted flow rate channeled into first stage air chamber 473 of first stage pump unit 470, reducing over filling or over pressurizing of first stage air chamber 473. Directional valve piston 411 is held stationary by the control air pressure in chambers 412 and 413 inside directional valve 410. Maximally restricted right process air exiting efficiency valve 460 and channeled to directional valve 410 is blocked by directional valve piston 411. Unrestricted left process air exiting efficiency valve 440 and channeled to directional valve 410, passes through directional valve piston 411 and directional valve 410 channeled to first stage pump unit 470 where it expands and pressurize first stage air chamber 472 acting on piston 471 in first stage pump unit 470. Pistons 471, 421 and 431 are conjoined by shaft 454. Once used fixed volume left process air in first stage air chamber 473 of first stage pump unit 470 exits first stage pump unit 470 and is channeled through directional valve 410 and directional valve piston 411 to pump unit 430 where it expands into and pressurizes larger volume second stage air chamber 432 to a lower pressure acting on piston 431. Both second stage air chamber 432 and first stage air chamber 473 are at equal lower pressures. Simultaneously, twice used right process air is released from second stage air chamber 422 out of pump unit 420 and channeled through directional valve 410 to atmosphere. The combined air pressure forces acting on pistons 471, 421 and 431, all conjoined by shaft 454, moves piston 471, 421 and 431 in a direction that displaces liquid from liquid chamber 433 in pump unit 430 and draws liquid into liquid chamber 423 in pump unit 420. Simultaneously, lower pressure once used right control air from second stage air chamber 432 in pump unit 430 enters efficiency valve 460 and passes around efficiency valve piston 461 exiting efficiency valve 460 through port 463 and is channeled to directional valve 410 where it enters and pressurizes chamber 412 acting on directional valve piston 411, allowing directional valve piston 411 to remain held to the right in directional valve 410.
Definitions
The following definitions are provided for claim construction purposes:
The word “restrict” does not mean to shut off completely. Accordingly, if a flow is “restricted,” the flow is not completely shut off.
Present invention: means “at least some embodiments of the present invention,” and the use of the term “present invention” in connection with some feature described herein shall not mean that all claimed embodiments include the referenced feature(s).
Embodiment: a machine, manufacture, system, method, process and/or composition that may (not must) be within the scope of a present or future patent claim of this patent document; often, an “embodiment” will be within the scope of at least some of the originally filed claims and will also end up being within the scope of at least some of the claims as issued (after the claims have been developed through the process of patent prosecution), but this is not necessarily always the case; for example, an “embodiment” might be covered by neither the originally filed claims, nor the claims as issued, despite the description of the “embodiment” as an “embodiment.”
Although the present invention has been described in connection with a preferred embodiment, it should be understood that modifications, alterations, and additions can be made to the invention without departing from the scope of the invention as defined by the claims.

## Claims

1. An air-driven pump comprising:
a source of pressurized air;
a first pump unit including a first pump chamber, a first air chamber and a first pump piston therebetween;
a second pump unit including a second pump chamber, a second air chamber and a second pump piston therebetween,
a directional control valve in communication with the source of pressurized air and the first and second air chambers, the directional control valve shifting responsive to end of stroke positions of the pump pistons to selectively control process air communication between the source of pressurized air and the first and second air chambers;
an efficiency valve pneumatically between the source of pressurized air and the directional control valve and responsive to selected positions of the pump pistons to restrict process air communication between the efficiency valve and the directional control valve, the selected positions of the pump pistons being as the pump pistons move toward the end of stroke positions of the pump pistons, respectively, and before the directional control valve has shifted;
a first air passage communicating from the efficiency valve to the first air chamber through the directional control valve;
a second air passage communicating from the efficiency valve and to the second air chamber through the directional control valve, the efficiency valve including a first valve position having unrestricted process air communication with the first air passage and maximally restricted process air communication with the second air passage and a second valve position having unrestricted process air communication with the second air passage and maximally restricted process air communication with the first air passage, wherein the process air communication from the first and second air passages to the first and second air chambers, respectively, is controlled by the shifting of the directional control valve.

2. The air-driven pump of claim 1, the first and second valve positions switching at each of the selected positions of the pump pistons.

3. The air-driven pump of claim 1, the source of pressurized air being in continuous process air communication with the directional control valve across the efficiency valve and through the first and second air passages.

4. The air-driven pump of claim 1, the efficiency valve further including efficiency valve shifting elements extending into the first and second air chambers to selectively engage the pump pistons.

5. The air-driven pump of 4, the first and second valve positions switching at each of the selected positions of the pump pistons.

6. The air-driven pump of claim 1 further comprising:
a pilot valve system shifting the directional control valve to selectively control the directional control valve responsive to the end of stroke positions of the pump pistons.

7. An air-driven pump comprising:
a source of pressurized air;
a first pump unit including a first pump chamber, a first air chamber and a first pump piston therebetween;
a second pump unit including a second pump chamber, a second air chamber and a second pump piston therebetween,
a directional control valve in communication with the source of pressurized air and the first and second air chambers, the directional control valve shifting responsive to end of stroke positions of the pump pistons to selectively control process air communication between the source of pressurized air and the first and second air chambers;
an efficiency valve pneumatically between the source of pressurized air and the directional control valve and responsive to two selected positions of the pump pistons to maximally restrict process air communication from the source of pressurized air to the first and second air chambers, respectively, through the directional control valve, the two selected positions of the pump pistons being as the pump pistons move toward the end of stroke positions of the pump pistons, respectively, and before the directional control valve has shifted, the efficiency valve including efficiency valve shifting elements extending into the first and second air chambers to selectively engage the pump pistons, wherein the process air communication from the efficiency valve at the two selected positions of the efficiency valve to the first and second air chambers, respectively, is controlled by the shifting of the directional control valve.

8. The air-driven pump of claim 7, process air communication without restriction and restricted process air communication between the source of pressurized air and the directional control valve being separate and concurrently open through the efficiency valve.

9. The air-driven pump of claim 8, the source of pressurized air being in continuous process air communication with the directional control valve through the efficiency valve.

10. The air-driven pump of claim 7 further comprising:
a pilot valve system shifting the directional control valve to selectively control the directional control valve responsive to the end of stroke positions of the pump pistons.

11. An air-driven pump comprising:
a source of pressurized air;
a first pump unit including a first pump chamber, a first air chamber and a first pump piston therebetween;
a second pump unit including a second pump chamber, a second air chamber and a second pump piston therebetween,
a directional control valve in communication with the source of pressurized air and the first and second air chambers, the directional control valve shifting responsive to end of stroke positions of the pump pistons to selectively control process air communication between the source of pressurized air and the first and second air chambers;
an efficiency valve system pneumatically between the source of pressurized air and the directional control valve and responsive to two selected positions of the pump pistons to maximally restrict process air communication from the source of pressurized air to the first and second air chambers, respectively, through the efficiency valve system and the directional control valve, the two selected positions of the pump pistons being as the pump pistons move toward the end of stroke positions of the pump pistons, respectively, and before the directional control valve has shifted, process air communication without restriction and restricted process air communication between the source of pressurized air and the directional control valve being separate and concurrently open through the efficiency valve system, wherein the process air communication from the efficiency valve at the two selected positions of the efficiency valve to the first and second air chambers, respectively, is controlled by the shifting of the directional control valve.

12. The air-driven pump of claim 11, the source of pressurized air being in continuous process air communication with the directional control valve through the efficiency valve system.

13. The air-driven pump of claim 11 further comprising:
a pilot valve system shifting the directional control valve at the end of stroke positions of the pump pistons to selectively control the directional control valve.

14. The air-driven pump of claim 13, the efficiency valve system including two efficiency valves, each efficiency valve having an efficiency valve piston in an efficiency valve cylinder and a shaft extending into one of the air chambers to selectively engage the pump piston therein.

15. The air-driven pump of claim 14, each efficiency valve having an unrestricted process air communication position and a restricted process air communication position.

16. The air-driven pump of claim 14, the pilot valve system including a pilot valve having pilot valve shifting elements extending into the air chambers to selectively engage the pump pistons therein.

17. The air-driven pump of claim 14, the pilot valve system including pilot passages through the valve pistons in each of the two efficiency valves.