Abstract:
A fluid pump apparatus includes a conduit, a material supported on and surrounded by the conduit, and an electrical energy source coupled to the material and configured to apply electrical energy to the material. The material is physically displaced relative to the conduit in response to the electrical energy. The conduit is configured to receive therein a fluid that is physically displaced relative to the conduit in response to the physical displacement of the material.

Description:
FIELD 
       [0001]    The present work relates generally to fluid pumps and, more particularly, to inaudible fluid pumps that support multiple configurations. 
       BACKGROUND 
       [0002]    Increased computation capability and functionality in mobile electronic devices has highlighted the need for cooling solutions. Typically some type of mechanical fan assembly is employed to move the air and provide necessary cooling. One conventional solution is referred to as “DCJ” or dual cooling jet technology. This technology uses piezo-electric (PZE) materials to create a ‘bellows’ effect that pulls and pushes air to create an air flow. A DCJ “bellows” is only a few millimeters thick, making DCJ useful in a variety of installation environments, and highly preferred for portable electronic devices. However, to achieve significant air flow, DCJ must run near the resonant frequencies of the PZE material. Disadvantageously, the resonant frequencies are in the 100-200 Hz range, causing the bellows to behave like a speaker, producing loudly audible noise. 
         [0003]    It is desirable in view of the foregoing to provide for a cooling solution that has wide applicability, including mobile electronic devices, that does not produce audible noise. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]      FIG. 1  diagrammatically illustrates a fluid pump according to example embodiments of the present work. 
           [0005]      FIG. 2  diagrammatically illustrates an electrical apparatus according to example embodiments of the present work. 
           [0006]      FIG. 3  diagrammatically illustrates a fluid system according to example embodiments of the present work. 
           [0007]      FIGS. 4-6  are diagrammatic plan views of the conduit of  FIGS. 1-3  according to example embodiments of the present work. 
       
    
    
     DETAILED DESCRIPTION 
       [0008]    Example embodiments of the present work exploit a principle used in conventional PZE motors, resulting in a quiet cooling solution with wide applicability. Some conventional PZE motors have a ring of PZE material on which a traveling wave is created by application of electrical energy. The traveling wave manifests as displacements of PZE material that contact an adjacent frictional ring such that the traveling wave imparts to the frictional ring a rotational force that causes the frictional ring to rotate. Such PZE motors are typically used, for example, in industrial applications and in camera autofocus mechanisms. The PZE material is electrically excited at approximately 60 kHz, which is well out of the audible range. 
         [0009]    As shown diagrammatically in  FIG. 1 , example embodiments of the present work provide a fluid pump  10  that includes a strip of PZE material disposed in a channel  12  defined within a conduit  13 . The PZE material is supported on one side of the conduit (i.e., one side of the channel). In some embodiments, the width of the PZE strip and the size of the channel are such that, when the PZE material is excited in response to electrical energy applied by a frequency control drive  15 , the PZE material is displaced relative to the conduit  13 , and crosses the channel  12  to contact (or nearly contact) the other side of the conduit  13  and substantially block the channel  12 . If the PZE material is excited at around 60 kHz, the displaced PZE material forms a traveling wave that travels along the length of the conduit  13 , so that fluid in the conduit  13  is propelled through the channel  12  along the length of the conduit  13 . 
         [0010]      FIG. 1  shows a plurality of convex portions that each represents displaced PZE material forming part of the traveling wave. The PZE material is supported on one side (bottom in the  FIG. 1  example) of the conduit  13 , and the convex portions contact (or nearly contact) the other side (top in the  FIG. 1  example) of the conduit  13 . This substantially eliminates fluid flow between the conduit  13  and the (contacting or nearly contacting) convex portions of PZE material. Thus, as the convex portions travel through the conduit  13  from end to end (left to right in  FIG. 1 ), they push the fluid in the travel direction of the traveling wave, resulting in fluid flow in the desired direction, as shown at  16 . 
         [0011]    In some embodiments, the conduit  13  is constructed from an electrically conductive material to which the PZE material readily adheres. Such materials are well known to workers in the art. In some embodiments, the outer surface of conduit  13  is clad with an insulating material. In some embodiments, the conduit  13  is structured as a tube with an annular cross-sectional profile. In various embodiments, the conduit  13  has an approximately circular cross-sectional profile, and the channel  12  has a diameter that ranges from 1 mm to 10 mm. Various embodiments of the conduit have various cross-sectional profiles. 
         [0012]    In some embodiments, the PZE material, when not energized, substantially blocks the channel  12 . In this case, when energy from frequency control drive  15  displaces the PZE material, the convex portions shown in  FIG. 1  represent the un-displaced PZE material, and the displaced PZE material creates a traveling wave of “pockets” between the convex portions. The traveling wave of pockets produces a vacuum pump type of operation. 
         [0013]    In the example of  FIG. 1 , both ends of the conduit  13  are open, such that fluid surrounding the conduit  13  enters at one end of the conduit  13 , is propelled through the channel  12 , and exits the other end of the conduit  13 . In some embodiments, however, one end of the conduit  13  is arranged in fluid communication with a fluid source, for example, a fluid supply reservoir, such that fluid is drawn from the source into the conduit  13 , and propelled through the channel  12  to exit the other, open end of the conduit  13 . 
         [0014]      FIG. 2  diagrammatically illustrates an electrical apparatus (e.g., a mobile electronic device in some embodiments) according to example embodiments of the present work. The fluid pump  10  of  FIG. 1  is arranged to propel a coolant fluid (for example, ambient air surrounding the pump  10 ), shown at  23 , across an electrical circuit assembly  21 , at locations proximate the assembly  21 , to cool its constituent electrical circuitry. The constituent circuitry of the assembly  21  performs a desired function of the apparatus. As shown by broken line, some embodiments use conventional techniques to mount a heat sink  22  in thermal contact with the electrical circuit assembly  21 , and the coolant fluid at  23  is propelled across the heat sink  22 . It will be appreciated that the coolant fluid, as propelled by the fluid pump  10 , effects convection transfer of heat away from locations proximate the electrical circuit assembly  21 . It will also be appreciated that the electrical circuit assembly  21  is merely an example. In various embodiments, the electrical circuit assembly  21  is replaced by various targets that benefit from cooling. 
         [0015]    In still further embodiments, the pump  10  provides pressurized fluid for various applications where such is required. Automotive applications and medical applications (where the fluid may, for example, include a medication) are but two categories among numerous other examples that will be familiar to workers in the art.  FIG. 3  diagrammatically illustrates such a fluid system according to example embodiments of the present work. The conduit  13  of pump  10  is arranged to provide fluid flow to a destination  31  that utilizes pressurized fluid. One end of conduit  13  is arranged in fluid communication with a source of fluid (e.g., a reservoir in some embodiments) shown generally at  33 , and the other end of conduit  13  is arranged in fluid communication with the destination  31 . In some embodiments, the destination  31  is a mechanical assembly that requires pressurized fluid for mechanical operation. In some medical application embodiments, the destination  31  is, for example, a living patient (e.g., human or animal). As shown by broken line, some embodiments provide a return fluid path  35  from the destination  31  to the fluid source  33 . 
         [0016]    In various embodiments, the conduit  13  has various configurations in its longitudinal direction (proceeding generally left-to-right in  FIG. 1 ) to accommodate a variety of applications. Some general examples of longitudinal configurations of the conduit  13  are shown in the diagrammatic plan views of  FIGS. 4-6 .  FIG. 4  shows a straight line configuration,  FIG. 5  shows a simple curved configuration, and  FIG. 6  shows a more complex curved configuration. The complex curve example shown in  FIG. 6  is also referred to herein generally as a “serpentine” configuration. It will be appreciated that the possible longitudinal configurations are virtually without limit. 
         [0017]    Any of the general examples of two-dimensional shapes shown in  FIGS. 3-5  may be either planar or non-planar relative to the third dimension. Any configuration that is non-planar in the third dimension may have any desired non-planar configuration in that third dimension, for example, curved, serpentine, etc. As an illustrative example, a conduit having a three-dimensional spiral configuration is a specific instance of a two-dimensional serpentine configuration that has a serpentine configuration in the third dimension also. It will be appreciated that the possible three-dimensional configurations of the conduit  13  are virtually without limit. 
         [0018]    Various embodiments use various commercially available materials instead of PZE material. Examples include electro-active polymers and so-called ‘artificial muscle’. More generally, any material that experiences physical displacement in response to application of electrical energy (e.g., electric field, magnetic field, electric current, etc.) may be used instead of the PZE material. 
         [0019]    Because the fluid pump according to example embodiments of the present work is operated at an ultrasonic frequency (e.g., 60 kHz), its operation is inaudible. Because the conduit  13  may have virtually any desired shape and size, the pump  10  is useful in myriad applications. 
         [0020]    Although example embodiments of the present work have been described above in detail, this does not limit the scope of the work, which can be practiced in a variety of embodiments.