Abstract:
A fluid-gas separator includes a gas-permeable membrane arranged sufficiently adjacent to a fluid-permeable membrane to allow the separation of fluid and gas flowing therein independent of the orientation of the fluid-gas separator itself.

Description:
BACKGROUND  
       [0001]     Certain fluid delivery devices need to remove air or other gas from the fluid before it is delivered to a destination. By way of example, in printing devices, such as, inkjet printers, it is desirable to remove air and/or other gases from ink that is being supplied to a printhead because the printhead may malfunction when air or other gases interfere with its operation. Another exemplary fluid delivery device is an intravenous drug/fluid delivery device, wherein it is desirable to remove air or other gases prior to delivering the drug/fluid to a patient.  
         [0002]     To remove air or other gas from a fluid, these and other like fluid delivery devices typically use a purging mechanism that separates the air/gas from the fluid. Such purging mechanisms are typically designed to operate in a particular orientation and as such may fail to operate correctly if their orientation changes. It would be desirable to have a fluid-gas separator that can operate in a variety of different orientations without failing. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0003]     The following detailed description refers to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure (Fig.) in which the reference number first appears. Moreover, the same reference numbers are used throughout the drawings to reference like features and components.  
         [0004]      FIG. 1  is a block diagram depicting an exemplary fluid delivery device having a fluid-gas separator, in accordance with certain embodiments of the present invention.  
         [0005]      FIGS. 2A and 2B  are illustrative diagrams depicting a cross-sectional view of an exemplary fluid-gas separator, in accordance with certain embodiments of the present invention.  
         [0006]      FIG. 3  is an illustrative diagram depicting a cross-sectional view of an exemplary fluid-gas separator, in accordance with certain other embodiments of the present invention.  
         [0007]     FIGS.  4 A-E are illustrative diagrams depicting exemplary shapes for a gas-permeable membrane and a fluid-permeable membrane for use in a fluid-gas separator, in accordance with certain different embodiments of the present invention.  
         [0008]      FIG. 5  is a block diagram depicting an exemplary printing device having a fluid delivery device that includes a fluid-gas separator, in accordance with certain embodiments of the present invention.  
         [0009]     FIGS.  6 A-B are illustrative diagrams depicting cross-sectional views of two exemplary fluid-gas separators, in accordance with certain other embodiments of the present invention.  
         [0010]      FIG. 7  is an illustrative diagram depicting a test drop height measurement technique from a side view and a top view, in accordance with certain other embodiments of the present invention.  
         [0011]      FIG. 8  is an illustrative diagram depicting a cross-sectional view of a gas-permeable membrane having a plurality of layers, in accordance with certain further embodiments of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0012]      FIG. 1  is a block diagram depicting an exemplary fluid delivery device  100 , in accordance with certain embodiments of the present invention.  
         [0013]     Fluid delivery device  100  includes a fluid source  102  that is configured to hold at least one fluid. Fluid source  102  is coupled a drive potential  106  through a conduit  104  in a manner that allows the fluid held in fluid source  102  to be withdrawn via conduit  104 . Drive potential  106  is representative of a variety of mechanisms that urge the withdrawal of fluid from fluid source  102  through conduit  104  and then into conduit  108 . By way of example, drive potential  106  may include a pump or the like. In certain implementations, drive potential  106  may include an arrangement that employs gravity to urge the movement of the fluid.  
         [0014]     Conduit  108  is further coupled to an inlet of a fluid-gas separator  110 . Fluid-gas separator  110  is configured to at least substantially separate gas that may be present in the urged flowing fluid. The separated gas exit fluid-gas separator  110  through a gas outlet. In this example, a conduit  116  directs the gas or gasses to an optional gas destination  118  that collects or otherwise processes the gas in some manner. In certain implementations, gas destination  118  may be configured to return the gas to fluid source  102  or into another component of device  100 . In other examples, conduit  116  and/or the gas outlet may be configured to simply release the gas into the atmosphere.  
         [0015]     Fluid-gas separator  110  also includes a fluid outlet that is coupled to conduit  112 . The fluid having been separated from the gas continues to be urged by drive potential  106  through conduit  112  to at least one fluid destination  114 .  
         [0016]     Conduits  104 ,  108 ,  112 , and  116  are representative of one or more structures or other arrangements that allow the urging by drive potential  106  of the fluid or fluid-gas mixture to occur. By way of example, in certain implementations such conduits may include tubes, pipes, channels, guides, filters, connectors, valves, gauges, sensors, heaters, etc.  
         [0017]      FIG. 1  has been illustrated, through the use of gray shading, to better show the flow of fluid (shaded) and gas (non-shaded) within device  100 . As shown by the breaks in the shading within conduits  104  and  108 , gas may become mixed with the fluid. Fluid-gas separator  110  separates the gas from the fluid as illustrated by the continuous shading within conduit  112 .  
         [0018]      FIGS. 2A and 2B  are illustrative diagrams depicting a cross-sectional view of an exemplary fluid-gas separator  110 , in accordance with certain embodiments of the present invention.  
         [0019]     As shown in  FIG. 2A , fluid-gas separator  110  includes a body or housing  202  having an inlet  212  through which a fluid and gas mixture can flow into a chamber  208   a  within housing  202 . Chamber  208   a  is separated by a chamber  208   b  by a gas-permeable membrane  204 . Gas-permeable membrane  204  is configured to allow gas within chamber  208   a  to pass through membrane  204  and enter chamber  208   b . Gas-permeable membrane  204  is configured to not allow fluid within chamber  208   a  to enter chamber  208   b . Gas that passes through gas-permeable membrane  204  and into chamber  208   b  may then exit separator  110  via gas outlet  216   
         [0020]     Gas-permeable membrane, materials are well known. Gas-permeable membrane  204  may include, for example, a hydrophobic material, an oleophobic material, or the like. As depicted in  FIG. 8 , gas-permeable membrane  204 ′ may also include two or more layers of materials, such as, an interface layer  802  and a backing layer  804 . Such layers may be bonded or otherwise held together. Here, interface layer  802  is configured to allow the gas to pass through it but not the fluid as described above, and backing layer  804  is configured to provide structural support to interface layer  802  while also allowing the gas to pass therethrough. Note that  FIG. 8  is illustrative only and hence the layers are not necessarily drawn to scale.  
         [0021]     Gas-permeable membrane  204 / 204 ′ may include, for example, a “breathable” or microporous material such as a fabric, membrane, laminate, etc, made from polytetrafluoroethylene (PTFE), expanded PTFE, porous PTFE, or other like materials. One example, of such materials includes GORE-TEX™ ePTFE based membrane material, currently sold for packaging vents in a laminate form by W. L. Gore and Associates, Inc. of Newark, Del. This is just one example; those skilled in the art will recognize that other types of gas-permeable materials may also be used.  
         [0022]     Fluid within chamber  208   a  is urged through a fluid-permeable membrane  206 . Fluid-permeable membrane  206  is configured to allow fluid to pass through it from chamber  208   a  into a fluid outlet  214 . Once properly wetted, fluid-permeable membrane  206  is configured to not allow gas to pass through it from chamber  208   a  into a fluid outlet  214 . Instead, the gas within chamber  208   a  will pass through gas-permeable membrane  204  into chamber  208   b  as described above.  
         [0023]     Fluid-permeable membrane  206  may include any material that exhibits appropriate fluid-permeability and gas-impermeability properties when wetted. Fluid-permeable membrane  206  may, for example, include hydrophilic, oleophilic, or other like materials. Fluid-permeable membrane  206  may include one or more materials in one or more layers. By way of example, fluid-permeable membrane  206  may include fabric, a screen, a mesh, or the like with openings sized to allow fluid to pass therethrough but not gaseous bubbles once wetted.  
         [0024]     In accordance with certain aspects of the present invention, once gas-fluid separator  110  is properly primed with the fluid/gas mixture, the amount of pressure (e.g., bubble pressure) needed to force the gas through gas-permeable membrane  204  is less than the amount of pressure needed to force the gas through wetted fluid-permeable membrane  206 . Conversely, while gas-fluid separator  110  is primed and operating, the amount of pressure needed to force the fluid through wetted fluid-permeable membrane  206  is less than the amount of pressure needed to force the fluid through non-wetted gas-permeable membrane  204 .  
         [0025]     In this example, a portion of membranes  204  and  206  are positioned adjacent one another within chamber  208   a  with a small gap  210  separating them. Gap  210  is small enough to prevent the gas within chamber  208   a  from forming one or more bubbles or a layer that significantly or completely covers fluid-permeable membrane  206 . If such were to occur, then it is possible that the urged fluid may force some of the gas through fluid-permeable membrane  206 . Gap  210  may be sized, therefore, based on any number of factors including, for example, the type of fluid(s), the type of gas(s), membrane characteristics, fluid pressures, etc.  
         [0026]     The size of gap  210  may be determined, for example, by testing gas-permeable membrane  204  using the fluid as illustrated in  FIG. 7 . The upper drawing shows a side view and the lower drawing shows a top view. Here, a test drop  702  of the fluid is placed onto a non-wetted surface  704  of gas-permeable membrane  206 . Test drop  702 , in this example, covers an area  706  that is about the same size as a corresponding area of fluid-permeable membrane  206 . A test drop height  710  of test drop  702  is then measured. Test drop height  710  may then be considered to represent a maximum size (distance) for gap  210 , for example, should separator  110  be intended for operations in different orientations. In certain implementations, gap  210  may therefore be sized to be less than test drop height  710 .  
         [0027]      FIG. 3  is an illustrative diagram depicting a cross-sectional view of an exemplary fluid-gas separator  110 ′, in accordance with certain other embodiments of the present invention. Fluid-gas separator  110 ′ is similar to fluid-gas separator  110  of FIGS.  2 A-B, with the exception that gap  210  between gas-permeable membrane  204  and fluid-permeable membrane  206  no longer exists. Instead, gas-permeable membrane  204  and fluid-permeable membrane  206  are actually in physical contact with one another, forming contact interface  302 . In certain embodiments, gas-permeable membrane  204  may be configured to flex or otherwise move in response to fluid pressure within chamber  208   a  thereby opening contact interface  302  in such a manner to allow fluid to flow from chamber  208   a  through fluid-permeable membrane  206 .  
         [0028]     In accordance with certain aspects of the present invention, fluidgas separators  110  and  110 ′ can be configured to operate in multiple, it not all, orientations by selecting a small enough gap  210  or providing a contact interface  302 . In such a configuration gas bubbles should come into contact with gas-permeable membrane  204  before or at about the same time that they would contact fluid-permeable membrane  206 . As a result, the gas will flow through gas-permeable membrane, which is configured to provide a lower resistance for gas flow than fluid-permeable membrane  206 . Thus, as pressure builds or is applied by the urging of drive potential  106  within chamber  208   a  the gas will be forced out of the mixture through gas-permeable membrane  204 .  
         [0029]     The exemplary embodiments of FIGS.  2 A-B and  FIG. 3  illustrate membranes  204  and  206  has having a substantially planer shape. It should be understood, however, that one or both of these membranes may have a non-planer shape. Furthermore, the size and/or surface area of one or more of these membranes may vary depending upon the application. Thus, in certain implementations, membrane  206  may be larger than membrane  204 . Also, in certain implementations there may be more than one gas-permeable membrane, and/or more than one fluid-permeable membrane.  
         [0030]     Some exemplary shapes for membranes  204  and/or  206  are illustrated in FIGS.  4 A-E, in accordance with certain different embodiments of the present invention.  FIG. 4A  depicts a substantially planer disk shaped gas-permeable membrane  402   a  and a substantially planer disk shaped fluid-permeable membrane  402   b .  FIG. 4B  depicts a substantially planer rectangular shaped gas-permeable membrane  404   a  and a substantially planer rectangular shaped fluid-permeable membrane  404   b .  FIG. 4C  depicts a cylindrically shaped gas-permeable membrane  406   a  and a cylindrically shaped fluid-permeable membrane  406   b .  FIG. 4D  depicts a conically shaped gas-permeable membrane  408   a  and a conically shaped fluid-permeable membrane  408   b .  FIG. 4E  depicts a spherically shaped gas-permeable membrane  410   a  and a spherically shaped fluid-permeable membrane  410   b.    
         [0031]      FIG. 5  is a block diagram depicting an exemplary printing device  500  having a fluid-gas separator  110  (or  110 ′), in accordance with certain embodiments of the present invention.  
         [0032]     Printing device  500  includes an ink source  502  that is configured to hold ink. Ink source  502  is coupled a pump  506  through a conduit  504  in a manner that allows the ink held in ink source  502  to be withdrawn via conduit  104 . Conduit  508  is further coupled to an inlet of a fluid-gas separator  110  (or  110 ′). Fluid-gas separator  110  (or  110 ′) is configured to at least substantially separate air that may be present in the urged flowing ink. The separated air exits fluid-gas separator  110  (or  110 ′) through an air outlet  516 , whereby the air is released into the atmosphere.  
         [0033]     Fluid-gas separator  110  (or  110 ′) also includes a fluid outlet (not shown) that is coupled to conduit  512 . The ink having been separated from the air continues to be urged by pump  506  through conduit  512  to a printhead  514 . Printhead  514  is configured to selectively eject droplets of the ink onto a medium (not shown) as part of printing operation.  
         [0034]     FIGS.  6 A-B are illustrative diagrams depicting cross-sectional views of two exemplary fluid-gas separators  610  and  610 ′, respectively, in accordance with certain further embodiments of the present invention. Fluid-gas separator  610  is similar to fluid-gas separator  110  and fluid-gas separator  610 ′ is similar to fluid-gas separator  110 ′. In both of these examples, however, gas outlet  216  is inherently formed by housing  602  such that a back-side  620  of gas-permeable membrane  204  is directly exposed to a surrounding environment  622  which functionally serves as chamber  208   b.    
         [0035]     Although the above disclosure has been described in language specific to structural/functional features and/or methodological acts, it is to be understood that the appended claims are not limited to the specific features or acts described. Rather, the specific features and acts are exemplary forms of implementing this disclosure.