Abstract:
The invention is a magnetically driven pump with a floating impeller and driven magnet, and the invention includes an impeller surface having geometric figures acting as the pumping bodies.

Description:
FIELD OF THE INVENTION 
     The present invention relates to centrifugal pumps, more particularly, the housing design for a magnetically driven centrifugal pump, and to a novel impeller design. 
     BACKGROUND OF THE INVENTION 
     Centrifugal pumps use an impeller and volute to create the partial vacuum and discharge pressure to move water through the pump. A centrifugal pump works by the conversion of the rotational kinetic energy, typically from an electric motor or turbine, to an increased static fluid pressure. An impeller is a rotating disk coupled to the motor shaft within the pump casing that produces centrifugal force with a set of vanes. A volute is the stationary housing in which the impeller rotates that collects and discharges fluid entering the pump. Impellers generally are shaft driven, have raised radially directed vanes or fins  1  that radiate away form the eye or center  3  of the impeller, and channels  2  are formed between the vanes. See  FIG. 10 and 11 . As the impeller turns, centrifugal force created by the rotating vanes pushes fluid away from the eye  3  where pressure is lowest, to the vane tips where the pressure is highest. Water is directed into the pump via input ports, generally positioned near the impeller eye or center  3 , and fluid flows within the pump is generally in the channels  2  between the vanes  1 . The pressurized fluid is directed by the volute to the discharge or outlet location of the pump. 
     Small pump applications, for instance for use in footspas or aquariums, generally are either propeller driven axial pumps, or centrifugal impeller type pumps. Smaller pumps are generally more inefficient, creating heat that must be dissipated. A novel impeller design and housing design are presented that allows for both heat dissipation and smooth flow characteristics suitable for a small pump. 
     SUMMARY OF THE INVENTION 
     The invention is a magnetically driven pump with a floating impeller and impeller surface having geometric figures acting as the pumping bodies 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective view of one embodiment of the magnet retainer housing 
         FIG. 2  is a rear perspective view of the embodiment of the magnet retainer housing of  FIG. 1   
         FIG. 3  is perspective view of a magnetically driven pump system 
         FIG. 4  is a cross section through one embodiment of the pump body. 
         FIG. 5  is a front exploded view of the magnet housing of  FIG. 1   
         FIG. 6  is a rear exploded view of the magnet hosing of  FIG. 1   
         FIG. 7A  is a front perspective view of one embodiment of the pump body 
         FIG. 7B  is a partial cutaway view of the pump body of  FIG. 7A   
         FIG. 7C  is a top view of the interior of the pump body of  FIG. 7A .  FIG. 8   
         FIG. 8  is a cross section through one embodiment of the magnet retainer housing 
         FIG. 9A  is a perspective view of one embodiment of the impeller showing fluid flow lines 
         FIG. 9B  is a cross section through a geometric figure depicting one embodiment of a sloped region. 
         FIG. 9C  is a cross section through a geometric figure depicting a second embodiment of a sloped region, with slightly reduced stability. 
         FIG. 9D  is a cross section through a geometric figure depicting a third embodiment of a sloped region. 
         FIG. 10  is a perspective view of a prior art vaned impeller 
         FIG. 11  is a top view of the impeller of  FIG. 10   
         FIG. 12  is a perspective view of the rear of one embodiment of a pump impeller. 
         FIG. 13A  is a top view of one embodiment of circle geometric figures, with dimensions disclosed for a small pump application. 
         FIG. 13B  is a side cross sectional view of the embodiment of  FIG. 13A  shown dimensions for a particular embodiment. 
         FIG. 14  is a cross section that shows a pump body suspended in a container holding fluid. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in  FIG. 3 , the pump system is a magnetically driven pump, such as described in U.S. Pat. No. 7,393,188 (hereby incorporated by reference). As described in the U.S. Pat. No. 7,393,188 reference, and as shown in  FIG. 14 , the pump system is used in combination with a container  102  provided for holding an amount of fluid  107 , such as liquid. It will be appreciated that the container  102  may be of any appropriate form, such as an aquarium. The side wall  106  of the container  102  has a first side  106   a  and a second side  106   b  oriented opposite and substantially parallel to each other. The fluid pump assembly  100  comprises a first casing  112  disposed outside the container  102  and housing a first magnetic assembly  114  operatively associated with a drive motor  118 , and a second casing  132  disposed inside the container  102  immersed within the liquid  107  and housing a second magnetic assembly  134 . See also the relationship in  FIG. 3  depicting a container wall  41 , the pump  10  to be mounted on the interior of wall  41 , and the motor  50  with driving magnet  51 , to be mounted on the exterior of the container wall  41  in mount bracket  60 . The magnetically driven pump system is quiet, efficient, and has a small foot print in the application interior. The magnetically driven pump system includes a driving motor  50  which turns a motor shaft and a driving motor magnet body  51  attached to the motor shaft. The motor magnet  51  is positioned adjacent to the exterior wall  41  of the application enclosure. Adjacent to the motor and driving magnet on the interior wall of the application is the pump, including the pump body  10 . 
       FIG. 4  shows an embodiment of the pump body  10 . Shown are the pump front  8  and rear  9  sections, creating a pumping chamber  101  therebetween. In a pump suitable for a spa environment, it is preferred that the pump inlet ports  7  and outlet ports  6  be located on the pump front portion  8  (see  FIG. 7A ). For other applications, the discharge port(s) may be located elsewhere, with pump output flow directed by a suitably located discharge diffuser or volute, for instance, for side discharge. 
     Located in the chamber  101  is a magnet retainer housing  17 , comprising a retainer bottom portion  19 , and a retainer top portion  18 . Impeller  30  is attached to the magnet retainer top portion  18 , here shown as integrally molded into the top portion. The bottom and top retainer portions  19  and  18  couple together creating an interior space or volume there between. Located in this retainer interior space is the pump magnet  20 . In this embodiment, the magnet  20  is firmly gripped in the interior of the magnet retainer housing  17  (there may be a snap body to snap the magnet in the magnet housing), so that rotation of the magnet  20  causes rotation of the impeller  30 , creating a rotative body. The magnet retainer housing may be dispensed with if the impeller is directly attached to the magnet. The magnet retainer housing  17  (or the magnet and impeller if the housing is not used) floats in the interior  101  of the pump housing, as later described. The driven pump magnet  20  and driving motor magnets  51  are of sufficient strength to be magnetically coupled through the application wall. Hence, as the motor magnet rotates, by action of the motor, the pump magnet also rotates by the coupling of the motor magnet with the pump magnet, thereby rotating the impeller. To assist in coupling, each magnet may have multiple N and S domains, where opposite domains face each other—for instance, a “N” domain on the motor magnet that is on the surface facing the pump magnet will align with an “S” domain on the driven pump magnet on the surface of the pump magnet that faces the motor magnet. At least two domains per magnet are desired on opposing faces. 
     One novel figure of the pump is the means to support the rotative body (here the magnet retainer housing  17 ) in the pump body. The interior face of the rear portion  9  of the pump body  10  has a center cutout or depression  22 , shown lined with a bushing  23  to reduce wear (see  FIG. 4 ), forming a rotation support. This support  22  is centered on the impeller  30 ; that is, the axis of rotation of the impeller  30  aligns with the cutout or support  22  on the interior face of the bottom portion  9  of the pump body  10 . The exterior bottom face of the rotative body, here the bottom portion  19  of the magnet retainer housing  17 , is generally a flat surface. However, in the present embodiment, positioned on this face is a raised shaped rotation center  80  that aligns with the rotation support  22 . As shown, the raised rotation center  80  is curved (here, the rotation center  22  is a curved bolt head, forming a portion of a hemisphere). The rotation center  80  has a diameter that is slightly larger than that of the diameter of rotation support  22  diameter. Hence, the rotative body&#39;s (magnet retainer housing  17 ) rear portion  19  is supported above the rear portion  19  of the pump body  10  (in one embodiment, about an  1 / 8  inch above the face) by the rotation center  80 , supported in the rotation support  22 . The magnet retainer housing  17 , while supported by the housing is detached form the housing, thus the rotating body thus substantially floats in the interior of the pump body  10 . When the rotation center  80  includes an opening allowing fluid flow, the rotative body will essentially hydroplane in the rotation support. The rotation center  80  is shaped to allow the magnet retainer housing  17  to pivot in the rotation support  22 . Alternatively, the rotation support  22  may be a curved depression surface (such as hemispherical shape, or a truncated hemisphere), of larger diameter that the rotation center, with the rotation center being a cylinder or a curved surface but of sufficient length to allow the magnet retainer housing  17  to pivot in the interior  101  of the pump body  10  about the rotation center  80 . Alternatively, the rotation support  22  may be a raised surface, with the rotation center being a depression or cutout in the magnetic retainer housing, with suitable diameters to allow the housing&#39;s axis of rotation to pivot about the rotation support  22 . The ability of the rotative body, here the magnet retainer housing  17 , to pivot about the rotation support  22  allows the driven pump magnet  20  to tilt of pivot its axis of rotation to better align with the axis of rotation of the driving pump magnet  51 . The axis of rotation may be tilted or cocked (as measured from a perpendicular from the rear of the pump housing) by several degrees (0-5 degrees, with a upper range of at least 2-3 degrees). Hence, if the plane of rotation of the driven motor magnet  51  is slightly misaligned from that of the rear of the pump body  10  (i.e., not parallel), the rotative body (here the rotating magnet retainer housing  17 ) will pivot about the rotation support  22  until good magnetic coupling and alignment is achieved between the two magnets (or the edge of the magnet retainer housing  17  contacts the interior wall of the chamber  101 ). 
     In the embodiment shown (see  FIG. 4 ), the center cutout  22  forms a through opening in the pump body rear portion  9 , allowing fluid communication through the center cutout opening  22 . This configuration is preferred, as fluid will flow through the opening  22 , reducing the friction caused by the rotation of the rotation support  80  in the center cutout  22 . The magnet retainer housing floats in the interior chamber due to hydroplaning. Fluid transport through this opening  22  also removes heat, providing for longevity of the pump. If the center cutout  22  is a opening in the housing, the housing rear portion  9  should have standoffs  5  to support the rear portion  9  of the pump body  10  away from the application wall so the opening  22  is not blocked by contact with the application wall (see  FIG. 12 ). 
     The pump also has a novel impeller  30 . The surface of the generally circular impeller  30  shown in  FIG. 1  does not have radial vanes, but instead includes several raised geometric figures  11 E having areas interior to the perimeter or edge of the geometric figures and disposed on the surface of the impeller  30 . The geometric figures  11 E are offset from the axial center or eye  31  of the impeller surface, leaving a substantially unobstructed eye. As show, the impeller has at least three geometric figures  11 E (here circles) being equally distributed about a periphery or circumference of the impeller. That is, for the number of figures “n”, the circular impeller can be divided into “n” regions (triangular pie shaped areas with the point of the pie at the center) where each region is congruent to every other region (see the three regions dashed depicted in  FIG. 13A . Each geometric  figure 11E  has a raised perimeter or edge having a leading portion  11 A, opposing a trailing portion  11 B, and a proximal portion  11 C (closest to the axial center  31 ), and an interior area  13  between the leading, trailing and proximal portions, where the area interior is at a lower height than the raised perimeter or edge  11 . It is preferred that the leading portion  11 A has a curvature that curves away from the direction of rotation, while the trailing portion  11 B has a curvature that curves into the direction of rotation (but not required, for instance, if the geometric  figure 11E  resembles a kidney bean shape). Hence, it is preferred that the curvature of the leading portion and trailing portion be opposed. The curvature of the leading and trailing portions are not required to be constant (for instance, an oval shaped figure), nor does the curvature of the leading portion have to match or mirror that of the trailing portion. The proximal portion  11 C connects the leading portion and trailing portion to create a substantially continuous perimeter or edge, and preferably is also a curved edge. As shown, the interior area  13  is at a height lower that the edge (here at the height of the surface of the impeller exterior to the figures). Each geometric  figure 11E  is separated from the others, creating channels between the figures. Dimensions of one particular impeller embodiment is shown in  FIG. 13 . 
     The raised edge  11  may also include a distal portion  11 D (closest to the perimeter of the impeller surface and furthest from the impeller center), thereby forming a substantially closed geometric  figure 11E , such as the circle shaped edge or perimeter shown in  FIG. 1 . A substantially closed geometric edge  11  is preferred if the pump discharge port(s) face the same direction as the input port(s), as later described. Substantially continuous means that the edge may have minor openings, such as an 1/16-⅛ opening in a ¾ inch diameter circle, as such minor openings do not substantially alter the pumping characteristics of the geometric  figure 11E  (wider openings may be tolerated near the center of the pump, as the fluid velocities are reduced here). Substantially closed means the geometric  figure 11E  has a substantially continuous perimeter and the perimeter generally encloses an area. 
     As shown, the raised edge  11  also has a sloped portion  12 , where the height of the edge decreases away from the eye  31  or axial center of the impeller surface—that is, the highest portion of the raised edge  11  is closer to the eye  31  of the impeller  30 , while the lowest portion is closer to the outer edge of the impeller  30 . In other words, the slope decreases from the proximal portion to the distal portion, and it is preferred that the slope decrease monotonically (this allows for flat spots near the distal and proximal portions, or elsewhere if desired). That is, both the leading and proximal portions should slope downwardly (preferably monotonically), but the slopes of the two portions do not have to match, although it is preferred that the leading portion and trailing portion be a mirror image (i.e. match). See  FIGS. 9B ,  9 C and  9 D for three slopes for the circles).  FIG. 9A  shows the figure sloped over the entire figure, with a constant slope;  FIG. 9B  shows the figure with an initial flat spot near the eye, sloping off thereafter at a constant slope;  FIG. 9C  shows a varying slope over the entire figure, where shape of the edge approximates log(x) or sqrt (X)(x&gt;1) (another shape would be that represented by the negative sloped surface of 1/x). As shown in  FIG. 9B , the sloped portion  12  of the edge does not have to extend over the entire length of the edge. A sloped portion is not required on the raised edge, but is preferred. The height of the leading portion does not need to be a mirror image of that of the trailing portion, although it is preferred. Finally, for a impeller that is tilted in the pumping chamber, it is preferred that the edges of the figures decline in height quickly (such as in  FIG. 9A , or where the edge of the figure approximates 1/x for instance). As the figures are above the face of the impeller, the figures, with sufficient tilt to the impeller, could contact or rub against the front interior surface of the pumping chamber, an undesired result. For a shaft driven impeller, where impeller tilt is not possible, the shape represented by  FIG. 9D  is preferred. 
     As shown in  FIG. 9A , the geometric figures  11 E are substantially circles, the preferred embodiment, although other curved geometric figures  11 E could be used. Preferably, geometric figures  11 E having leading portions and trailing portions with the curvature of these two being opposed, are preferred. Preferably the trailing portion curvature is concave to the direction of rotation, with the leading portion curvature being convex to the direction of rotation (i.e., from the center of the figure, the leading and trialing portions appear concave). For instance, geometric figures  11 E having teardrop shapes (with the broad part of the teardrop near the eye of the impeller) or wide oval shapes (with the long axis of the oval along a radial line from the center of the impeller) will give certain of the desired flow characteristics provided by circle geometric figures  11 E. Straight line segmented geometric figures are not preferred as two straight line segments create potential turbulence generated at the intersection or join of two line segments, particularly on the trailing edge. 
     As shown in the embodiment of  FIG. 1 , the distal portion  11 D of the geometric  figure 11E  is also raised above the impeller surface  30  and the interior area. Water pumped through the interior region  13  of the raised perimeter, when encountering the distal portion  11 D, will be given a velocity component perpendicular to the impeller surface. Such a velocity component is preferred when the outlet ports are directed perpendicular to the impeller surface, as in the embodiment shown in  FIG. 7A . Also as shown in  FIGS. 7C and 7B , the interior face of the rear portion  90  of the pump body  10 , has two arcuate volute channels  40  formed adjacent the periphery of the impeller. Each volute channel encompasses about 180 degrees with the widest part of the volute terminating near the outlet ports  6 . Each volute thus helps channel fluids exiting the impeller to one of the outlet ports  6 . 
     Flow patterns using circular geometric figures are depicted in  FIG. 9A . As shown, fluid is drawn in from the input port(s) into the eye or center region  31  of the impeller by the reduction in pressure near the impeller eye resulting from rotation of the geometric figures  11 E. The smooth interior face  11 G of edge  11  directs water outwardly through the interior region  13  of the geometric figures  11 E. The velocity of fluid directed outward in the channels between the geometric figures  11 E is less that that of waters exiting the impeller through the interior of the geometric  figure 11E , as the discharge area is greater at the channel periphery than it is through the interior of the geometric  figure 11E . Additionally, the channels are not as efficient as capturing and accelerating fluid as is the concave curvature of the trailing portion of a figure. 
     The pressure differential across the impeller surface having geometric figures (i.e. from the center to the periphery) is not as great as that created by a radially vane impeller, and hence the flow produced by the present impeller is believed to be slower, smoother and less turbulent and more suited for a small applications, such as a spa or aquarium. Additionally, the edge or perimeter forming the rotating figure preferably presents less of a profile (i.e., it is not as high) with distance from the center of the impeller. Hence, the rotating geometric  figure 11E  has less direct fluid contact with fluid away from the impeller eye, providing for smoother discharge of water from the impeller surface. Additionally, this decrease in contact surface area between the rotating impeller and flowing fluid, with distance from the eye, produces less drag on the impeller than would be present without the sloped region. This reduction in drag helps keep the driven pump magnet aligned with the driving motor magnet, which is not subject to any fluid drag force. 
     Finally, any raised geometric figure on an open rotating impeller will form a bow wave generated by the top edge of the rotating figure. The sloped design of the applicant&#39;s geometric figure helps shape a bow wave that is more even and better formed with less turbulence. The bow wave generating figure edge reduces in height with distance from the center of impeller, helping to counter the effects of an increase in velocity of the figure with distance from the impeller center. The impeller is shown on a magnetically driven pump, but it could be used on any pump where low turbulence is desired. That is, the impeller may be adapted to be driven by a motor directly (shaft driven) or indirectly, for instance, magnetically driven.