Patent Publication Number: US-2015078919-A1

Title: Pressure differential pumps

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application Ser. No. 61/879,872, filed Sep. 19, 2013, titled “Pressure Differential Pump,” the entire contents of which are hereby incorporated by reference. 
    
    
     FIELD OF THE DISCLOSURE 
     Embodiments of the present disclosure relate generally to pumps and systems that use a differential pressure gradient to transfer fluids. In one example, the pumps may use available differential pressure that exists due to outside pressure and cabin pressure due to altitude on-board a vehicle such as an aircraft. In other examples, the pumps may use a created differential pressure, such as that created by a vacuum generator pump on any vehicle. The pumps and systems may be designed to transport any type of fluids, non-limiting examples including fluids that may contain suspended solids, such as black or grey water, anti-freeze, or any other fluids. 
     BACKGROUND 
     Often aboard passenger transportation vehicles, there exist high or low pressure systems as a consequence of propulsion or environmental conditions. For example, an aircraft in flight may experience a pressure differential that is created between the atmosphere outside the aircraft at an altitude and the internal pressurized cabin atmosphere. These high or low pressure systems represent useful differential pressure gradients that can be used to drive certain mechanical processes. 
     BRIEF SUMMARY 
     Embodiments described herein provide a pump system configured to use differential pressure. The pump system may generally include a pump body comprising at least one vacuum inlet, at least one fluid inlet, an outlet, a vacuum control member, and a reservoir configured for containing a fluid. There may be at least one piston housed within the pump body, the piston configured to move in response to pressure differential. The piston may include a spring body or any other tension-compression storing system that can be compressed when subjected to vacuum and that expands when the pump body is vented to ambient pressure. It is also possible for the pump to work such that a difference in pressure forces a hydraulic cylinder to move across the pump body, forcing movement of fluid. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a side view of one embodiment of a pump system that uses differential pressure to move fluids. 
         FIG. 2  shows a side exploded view of a piston that may be contained within a pump body. 
         FIG. 3  shows a perspective view of the piston components of  FIG. 2 . 
         FIG. 4  shows a side cut-away view of a pump body with a vacuum applied to compress piston components or to otherwise force the pistons open to create a reservoir space in the pump body. 
         FIG. 5  shows a side cut-away view of  FIG. 4  with the pistons expanded to force fluid out of the reservoir. 
         FIG. 6  shows a schematic of a pump using a hydraulic cylinder to force fluid out of the reservoir. 
         FIG. 7  shows a cross-sectional view of a pump body having internal rails for guiding a piston. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure provide pumps designed to work based on differential pressure. The potential energy represented by differential pressure is particularly attractive in passenger transport vehicles, due to limitations on size, weight, and electrical energy inputs for various components. The present inventors thus determined that it would be beneficial to design pump devices that can use this energy source. Due to the inherent movement of passenger transportation vehicles as well as necessary size and weight restrictions for components to be used on such vehicles, on-board mechanisms are desirably small, lightweight, reliable, and able to function in a range of temperatures and environments. The pressure-differential pumps (PDP) described herein are devices that use the various pressure regimes available on-board a passenger transportation vehicle to drive fluids from one location to another. 
       FIG. 1  shows one example of a pressure differential pump (PDP) system  10 . This system includes a pump body  12 . The pump body  12  may be made up of two body components  14 ,  16 . However, although two body components  14 ,  16  are shown in  FIG. 1 , it should be understood that the body components  14 ,  16  may be integrally molded. It should also be understood that the pump body may be formed as a single integral body. Alternatively, there may be more than two body components provided to form the pump body  12 . In the specific embodiment shown in  FIG. 1 , the body components  14 ,  16  may be formed as pinch valves. The general concept is that the pump body  12  has a reservoir  18  that can contain a fluid, and the pump body can move the contained fluid. The pump body  12  may receive a first applied pressure, and may use that pressure to move contained fluid toward an area having a different pressure. By using different pressure gradients, the system  10  can move fluids without using a high amount of power. 
     In one example, the pump body  12  forms a reservoir  18 . The reservoir  18  may generally include one or more seals to prevent air and liquid leakages. The reservoir may be in fluid communication with an outlet  20 . The outlet  20  is an exit point for the contained fluid to leave the pump body  12 . In a specific embodiment, there may be more than one fluid outlet  20  provided. The pump body  12  also has at least one fluid inlet  22 . The at least one fluid inlet  22  allows any type of fluid to be received into the reservoir  18  of the pump body  12 . In a specific embodiment, there may be more than one fluid inlet  22  provided. In  FIGS. 1 and 4 , a pump inlet  22  is positioned on an outer surface of the pump body (leading to the reservoir  18 ). A pump outlet  20  is positioned generally opposite the inlet  22  on outer surface of the pump body  12  (leading away from the reservoir  18 ). 
     Fluid may be delivered into the pump body reservoir  18  using any appropriate manner. In one example, the fluid may be forced into the reservoir  18  from another system. The fluid may be grey water from a sink basin that flows into the pump body  12 . The fluid may be potable water delivered from an on-board water tank. The fluid may be anti-freeze to be delivered to one or more aircraft components. The fluid may be grey water that has been filtered, collected, and reserved from a sink for delivery to a toilet for flushing purposes. The type of fluid to be moved via a pump system  10  is not intended to be a limiting factor of the pump structures described. In another example, the volume of the pump reservoir  18  may collect fluids (from any source) drawn in by the vacuum-driven retreating action of one or more pistons  26 , described further below. An inlet check valve (A) may allow fluids to be pulled into the pump through the fluid inlet  22 , but prevent them from flowing backwards through the system during compression. Similarly, an outlet check valve (B) may allow fluids to pass through the outlet  20  (toward the pumping destination) during compression without allowing high pressure, downstream fluids to flow backward. 
     For example, as shown in  FIG. 2 , a piston system may be used to move water through the pump body  12 . This example may include at least one tension-compression element that may be housed within the pump body  12 . In one embodiment, the piston may include a compressible feature, such as a tension-compression element spring body  28 , and a head  30 . The piston head  30  may be attached to a yoke  50 , with the spring body  28  positioned within. The yoke  50  may be a sliding yoke that helps create movement of the piston. The yoke  50  may also feature a sleeve  32 , such as an elastomeric sleeve  32 , around its circumference. The sleeve  32  may slide with the yoke  50  and help reduce or alleviate friction between the yoke  50  and the pump body  12  interior. 
     In an alternate embodiment, the piston may comprise a compressible substance, such as gas, that can force movement of the piston head  30 . In any event, the piston is generally compressed when the pump body is open to vacuum, but expanded when the pump body is open to vent or ambient pressure. As shown in  FIG. 3 , the spring body  28  can be received in the yoke  50 , which is received in the pump body  12  in use. In one example, the spring body  28  of the piston may have a normally-extended resting state. This is illustrated in  FIGS. 2 and 3 . As shown in  FIG. 4 , a second piston  34  (with related components) may be positioned in the pump body  12  as well. The pistons  26 ,  34  may be positioned on opposing sides of the pump body  12 , such that when retracted, they help define the reservoir  18 . 
     In one example, the piston(s) may be formed of yoke  50  that is configured as a hollow cylinder suspended within an elastomeric sleeve  32 . Differential pressure may be applied to a sealed region behind the yoke/cylinder barrel. One or more tension/compression-storage components  28  may be located within this sealed region. In one embodiment, the tension-storage component may be a spring. The elastomeric sleeve  32  may act to atmospherically isolate the interior of the region behind the cylinder by bending or folding, while maintaining a seal, without sliding past itself or other components. This design can allow for reduced friction motion by eliminating a sealing component such as an o-ring. (However, it should be understood that an o-ring may be used instead or additionally.) This design can also allow the compression of the piston  26  via pressure differential benefit, while ensuring that remaining pump components remain isolated from the pumped fluids. This contributes to the overall reliability of the system over existing pump architectures. In one example, a low-friction sleeve  32  may be attached to a piston head  30  and piston yoke  50 . 
     In another embodiment, piston guidance may be maintained via one or more internal rails  48  instead of (or in addition to) an o-ring-containing piston or a sleeve  32 . The internal rails  48  may assist with assembly of the pump body components. The internal rails  48  may also help keep the piston from rotating in use. One example of one or more internal rails  48  positioned on an internal surface of the pump body is shown in  FIG. 7 . The piston  26  may be provided with one or more protrusions that slide within the rails  48 . Alternatively, the rails may be provided as an elongated protrusion on the pump body, and the piston may have one or more grooves that receive the elongated protrusion in use. 
     The movement of the piston(s)  26 ,  34  may be controlled by differential pressure. For example, most passenger aircraft and other passenger transport vehicles have a vacuum disposal system that applies vacuum to transport waste water from toilets and/or sinks into an on-board waste water storage tank. In aircraft, the vacuum is generated either by the pressure differential between the pressurized cabin and the reduced pressure outside of an aircraft at high flight altitudes or by a vacuum generator at ground level or at low flight altitudes. The pressure differential created by either system can be used to force the piston  26  to contract and to pull water into the space created by such movement. 
     In use, the interior of two normally-extended pistons  26 ,  34  may be exposed to vacuum. It is possible for each piston to be exposed independently to the same vacuum source or for them to be connected to separate vacuum sources. In any event, exposure to vacuum allows atmospheric pressure to push the pistons  26 ,  23  back into the yokes/cylinder barrels  50 , into a contracted state. In this position, the spring  28  on each piston  26 ,  34  may be compressed and stores the potential energy provided by the differential pressure gradient. It is with this potential energy that fluids can be pumped. In other embodiments, the pistons may be moved via vacuum alone, via hydraulic pressure, or via magnetic force. In one example, the pressure differential/vacuum may be applied to the pump body  12  via at least one vacuum inlet  36 . The at least one vacuum inlet  36  may deliver a vacuum created by an on-board vacuum generator or vacuum created by the difference in pressures between the aircraft cabin and the outside atmosphere.  FIG. 1  shows an embodiment that uses two vacuum inlets  36 ,  38  controlled by a vacuum control member  40 . It should be understood, however, that only one vacuum inlet need be provided (as shown in  FIGS. 4 and 5 ) or that more than two vacuum inlets may be provided. As shown in  FIG. 4 , an application of differential pressure to the pump body  12  can force the piston  26  to contract. This contraction creates spaces and vacuum for the entry of fluid into the at least one fluid inlet  22 . The inlets described herein may be operated by valves, such as pinch valves, solenoid valves, or any other appropriate valve that can control the flow of fluids (either liquid or gases). 
     A control member  40  may also be provided as a part of the pump system  10 . Control member  40  may be controlled by a vent valve (C), which may toggle between venting the system via a vent channel  44  or allowing vacuum to be applied to the system via a vacuum channel  46 . Control member  40  can cause the removal of the vacuum from the pump body, creating a pressure gradient, which can force the piston(s)  26 ,  34  to expand, pushing the fluid contained in the reservoir  18  out through the outlet  20 . An example of vent being applied to the pump body  12  to create a flush state is shown in  FIG. 5 . In this Figure, the pistons have expanded into the reservoir, which forces the fluid contained in the reservoir out as a high force/pressure/velocity. 
     Referring now more specifically to  FIG. 4 , the function of the various valves (a, b, and c) that coordinate flow of fluid is described. The below description is for use of the pump to receive grey water and to deliver the grey water to a toilet for a flush sequence, but it should be understood that other uses are possible and within the scope of this disclosure. When a vacuum is applied to the pump body  12 , the inlet valve (a) is open, allowing grey water/fluid to enter the reservoir  18 . (This entry may be via gravity, via pull from pressure, or via external pump, or any other appropriate method.) The outlet valve (b) is closed. The vent/vacuum valve (c) is opened to vacuum and closed to vent. (This valve (c) may be a 3-way valve or any other appropriate form of valve.) The pistons  26 ,  34  are compressed. 
     Entry of grey water into the reservoir  18  allows the downward passage of fluid, while preventing the upward backflow. Once a flush request is sent from the toilet to the pump system  10 , the following actions may occur to initiate the “pump state” shown in  FIG. 5 : the inlet valve (a) will close, the outlet valve (b) will open, the vent/vacuum valve (c) will open the vent channel  44  and close the vacuum channel  46 . These actions may cause the pistons  26 ,  34  to expand, pumping the grey water/fluid out of the reservoir  18  through valve (b) and out the outlet  20 . 
     Once the pistons are fully expanded, the following actions may occur to revert back to the “normal state” shown in  FIG. 4 : the inlet valve (a) will open, the outlet valve (b) will close, the vent/vacuum valve (c) will close the vent channel  44  and open the vacuum channel  46 . These actions will cause the pistons  26 ,  34  to compress, preparing the reservoir  18  for another cycle of refill with grey water. The valves used in this system may be any appropriate form of valve. It has been found that solenoid valves may be particularly useful. 
     When fully extended, the pistons  26 ,  34  may be designed to occupy a significant majority of the available volume of the pump reservoir  18 . The reservoir  18  shape may be optimized, depending upon the application of the pump system, such that the required pressure and volume of fluid can be delivered via the pumping action of the pistons. Further, piston action can operate in a single-stroke or multi-stroke fashion, delivering a bolus of pumped fluid or a pulsed stream. 
     In a single-stroke configuration, the full volume of the pump reservoir may be expelled during extension of the piston(s). The pressure of the pumped fluid may change in proportion to the available tension in the spring. As the spring returns to its uncompressed state (e.g., at the end of the stroke), the pressure of the fluid may be found to diminish. In this manner, fluid would generally be pumped as a discrete bolus, with a high initial pressure that diminishes over the course of the stroke. 
     In a multi-stroke configuration, the reservoir volume may only be reduced by a fraction during each piston stroke, allowing the fluid to be pumped at a generally high pressure, due to conservation of tension within the piston spring. Because each stroke is physically shorter, the differential pressure can more readily drive the piston recovery, allowing for rapid repetition of strokes. If a two-piston pump configuration is used, as shown in  FIGS. 4 and 5 , the piston actions may be timed to allow for a fairly smooth, constant flow of fluid as each piston complements the slack left by the decompression of the other piston&#39;s spring. 
     In some embodiments, it is envisioned that the pressure differential pump may use shape-memory alloys to achieve non-diminishing pumping pressures throughout the linear stroke of the piston. For example, the tension-compression element of the piston may comprise a shape memory material. Shape-memory allows, non-limiting examples of which include copper-aluminum-nickel or nickel-titanium, can be utilized such that the energy released during spring decompression can be supplanted by the reversible changes in these shape-memory alloys. 
     The pump system  10  may feature one or more level sensors, which may be comprised of non-intrusive capacitive sensors, to detect when and whether the reservoir  18  is full. The pump system  10  may also feature one or more controllers that send signals to the vacuum control member  40  to open and close the valves at the inlet and outlet and in order to effect pump activation and movement of the desired fluid. 
     In an alternate embodiment, rather than relying on spring motion to cause movement of the pistons, the pistons may operate based on vacuum alone. A vacuum may be applied to cause the piston to expand, pushing the fluid out of the reservoir. 
     In a further embodiment, it is possible to provide a single piston that is operated by pressure differentials across two ends of the pump body. At one end, a first pressure differential causes movement of a piston and pulls water into the reservoir  18 . Once the reservoir is full or when the pump is otherwise activated, a second pressure differential that enters at the second end of the pump body  12  can cause opposite movement of the piston and force fluid out of an outlet. 
     In a further embodiment, the pump system  10  may be activated by hydraulic pressure. For example, as shown in  FIG. 6 , one or more hydraulic cylinders  42  may be used to move fluid through the pump. The pump body  12  is generally provided with at least one fluid inlet  22 , at least one fluid outlet  20 , a liquid chamber  52 , and an air chamber  54 . The fluid inlet  22  and fluid outlet  20  are generally governed by check valves or other features that prevent flow of liquid until the valves are opened. A hydraulic cylinder  42  may be positioned within the liquid chamber  52  and used to force movement of the water that enters the chamber  52  out through the inlet  22 . The hydraulic cylinder  42  may be operated by a pressure created by fluid built up in the chamber  52  when the inlet and outlets are closed via valves. The hydraulic cylinder  42  may be operated by compressed gas or any other appropriate manner. 
     In the example shown in  FIG. 6 , the hydraulic cylinder  42  may include a piston  56  that moves within the liquid chamber  52 . The liquid chamber  52  features an inlet  22  and an outlet  20 . The liquid chamber  52  is separated from an air chamber  54 . The air chamber  54  has an air inlet  58  and a vacuum inlet  60 . (Although these inlets are shown as two separate elements, there may be a single inlet provided, and a control system may control the application of vacuum or vent to the inlet.) In use, when the air chamber  54  is evacuated by application of vacuum, the piston  56  moves to the right in  FIG. 6 . This pulls liquid into the water inlet  22 . (It should be understood that check valves may be positioned at each of the inlets/outlets in order to maintain the desired pressure across the vacuum inlet and the air inlet, as well as to prevent backflow of fluid between the fluid inlet  22  and the fluid outlet  20 .) 
     When air is pushed into (or otherwise allowed to enter) the air chamber  54 , this creates a differential pressure that forces the piston  56  to move to the left in  FIG. 6 , forcing liquid out of the liquid chamber  52 . For example, the air inlet  58  may have a valve that can be opened to allow vent air to rush in when the vacuum inlet  60  is closed via its valve. In this way, differential pressure causes movement of the piston, which causes movement of the liquid to be pumped. 
     The components of the pressure differential pump may constructed of any material that can withstand varied environments and pressures. One non-limiting example includes high-density plastic polymers, such as Ultem or PEEK. There are no heavy electromagnets or bearings required. The strength and low mass benefits of these polymer materials provides a value to passenger transport vehicles, where lightweight components can allow for reduced fuel consumption or additional passenger revenue. 
     It is envisioned that the disclosed pumps may operate on-board passenger transport vehicles such as watercraft vessels, trains, aircraft, as well as other vehicles. The wide variance in environmental conditions between these applications, such as humidity, temperature, salt exposure, and so forth may guide materials to be selected with possible the extremes in mind. 
     The fluids pumped by the device could vary widely based on application. In one proposed application, potentially low temperature fluids such as anti-freeze may be dosed and delivered to appropriate system components. In this example, the materials and mechanisms within the pump system  10  can be designed to withstand low temperatures encountered by aircraft at altitude or a train in winter, as well as be compatible to withstand various types of applicable fluids. For example, if the pump system  10  is used to pump potable water, materials with sufficient regulatory certification may be chosen to ensure water quality. For example, if the pump system  10  is used to pump grey water from a sink for delivery to an on-board toilet for use as flushing water, the materials may be chosen such that they can withstand various detergents, bacteria and other microorganisms over a period of time, and may have surfaces treated to withstand or discourage undesired microbial growth. For example, if the pump system  10  is used in medical or pharmaceutical applications, further increasing regulatory requirements may dictate materials and size requirements to be used. 
     It is understood that the present embodiments described may be modified for the specific application such that the pump fulfills the purpose of using differential pressure as the energy source. Modifications within the scope of this disclosure can include a different number of pistons, different reservoir shapes, check valve placement and quantity variation, and material changes. Changes and modifications, additions and deletions may be made to the structures and methods recited above and shown in the drawings without departing from the scope or spirit of the following claims.