Segmented driven-magnet assemblies for pumps, and pumps comprising same

Abstract

Driven-magnet assemblies are disclosed for use in magnetically actuated pumps such as gear pumps. An exemplary assembly includes a magnet-flux-ring assembly and a molded body. The magnet-flux-ring assembly includes a flux ring having inner and outer surfaces that are concentric around an axis, and multiple magnet segments at respective radial positions around the axis. Each magnet segment has a respective inner surface, outer surface, first end, second end, and lateral sides. The inner surfaces are attached side by side to the outer surface of the flux ring around the flux ring. The outer surfaces form an outer surface of the assembly. The molded body has at interior portion, a first end, and a second end. The interior portion is situated radially inwardly of, and attached to, the inner surface of the flux ring. The first end is integral with the interior portion and captures the first ends of the magnet segments relative to the flux ring. The second end is integral with the interior portion and configured to capture the second ends of the magnet segments relative to the flux ring. The outer surface of the assembly is substantially bare.

1 . A driven-magnet assembly for a magnetically driven pump, the assembly comprising: 
 multiple magnet segments each having a first end, a second end, and lateral edges, the magnet segments being situated at respective positions around a rotational axis in an arrangement having an inner surface and an outer surface, the inner and outer surfaces being coaxial about the rotational axis; and    a cage holding the magnet segments relative to each other in the arrangement, the cage comprising an interior portion, a first end, a second end, and at least one longitudinal outer portion, the interior portion being situated between the rotational axis and the inner surface of the arrangement and coaxially with the arrangement such that the inner surface of the arrangement is coupled to the interior portion of the cage and the magnet segments radially surround the interior portion, the first end of the cage being coupled to the interior portion and to the first ends of the magnet segments so as to hold the first ends of the magnet segments relative to each other in the arrangement, and the second end of the cage being coupled to the interior portion and to the second ends of the magnet segments so as to hold the second ends of the magnet segments relative to each other in the arrangement, the first and second ends of the cage being coupled together on the outer surface of the arrangement by the at least one longitudinal outer portion extending between the first and second ends substantially flush with the outer surface.    
   
   
       2 . The assembly of  claim 1 , wherein the at least one longitudinal outer portion is parallel to the rotational axis.  
   
   
       3 . The assembly of  claim 1 , wherein: 
 the first end of the cage is integral with the interior portion;    the second end of the cage is integral with the interior portion; and    the at least one longitudinal outer portion is integral with the first and second ends of the cage.    
   
   
       4 . The assembly of  claim 1 , further comprising a flux ring having an inner surface and an outer surface, wherein the inner surface of the arrangement is coupled to the outer surface of the flux ring, and the inner surface of the flux ring is coupled to the interior portion of the cage.  
   
   
       5 . The assembly of  claim 1 , wherein: 
 the lateral edges of the magnet segments have respective chamfers that define channels between adjacent magnet segments in the arrangement;    the cage comprises multiple longitudinal outer portions; and    the longitudinal outer portions are situated in the respective channels, substantially flush with the outer surface of the arrangement.    
   
   
       6 . The assembly of  claim 1 , wherein: 
 the lateral edges of adjacent magnet segments of the arrangement define at least one respective void extending radially from the outer surface of the arrangement to the inner surface of the arrangement; and    the cage includes respective radial portions extending through the voids and coupling the longitudinal outer portions of the cage with the interior portion of the cage.    
   
   
       7 . The assembly of  claim 6 , wherein the radial portions are coupled to respective longitudinal outer portions at substantially mid-length of the longitudinal outer portions.  
   
   
       8 . The assembly of  claim 1 , wherein: 
 the first end of the cage is configured to capture the first ends of the magnet segments together circumferentially; and    the second end of the cage is configured to capture the second ends of the magnet segments together circumferentially.    
   
   
       9 . The assembly of  claim 1 , wherein: 
 the ends of the magnet segments have respective stepped profiles that define radial channels between adjacent magnet segments in the arrangement; and    at least one of the first and second ends of the cage comprises radial portions that fill respective radial channels.    
   
   
       10 . The assembly of  claim 9 , wherein: 
 the at least one end of the cage comprises an inner portion and an outer portion; and    the radial portions extend between the inner portion and the outer portion.    
   
   
       11 . The assembly of  claim 1 , wherein the first end of the cage is configured for rotational coupling to a coaxially rotatable pump component so as to cause corresponding rotation of the pump component about the axis whenever the driven magnet is rotated about the axis.  
   
   
       12 . The assembly of  claim 11 , wherein: 
 the pump is a gear pump; and    the coaxially rotatable pump component is a driving gear of the gear pump.    
   
   
       13 . The assembly of  claim 1 , wherein the cage is made of a polymeric material.  
   
   
       14 . The assembly of  claim 1 , wherein the magnet segments in the arrangement have alternating magnetic polarity from one magnet segment to the next.  
   
   
       15 . The assembly of  claim 14 , wherein: 
 the arrangement comprises four magnet segments; and    the magnetic polarity alternates from radially inwardly directed to radially outwardly directed from one magnet segment to the next.    
   
   
       16 . The assembly of  claim 15 , wherein: 
 each magnet segment is configured as a respective quarter cylinder;    the magnet segments in the arrangement are situated side-by-side to form a cylinder of magnets around and coaxial with the interior portion of the cage.    
   
   
       17 . The assembly of  claim 16 , further comprising a flux ring having an inner surface and an outer surface, wherein the inner surface of the arrangement is coupled to the outer surface of the flux ring, and the inner surface of the flux ring is coupled to the interior portion of the cage.  
   
   
       18 . A pump, comprising: 
 a pump housing enclosing an active pump-component that, when rotated about an axis, generates a liquid-pumping force urging liquid to flow through the pump housing; and    a driven-magnet assembly that is rotatable about an axis and that is coupled to the active pump-component in a manner that causes the active pump-component to rotate about its axis whenever the driven-magnet assembly is rotated about its axis, the driven-magnet assembly comprising (i) multiple magnet segments each having a first end, a second end, and lateral edges, the magnet segments being situated at respective positions around a rotational axis in an arrangement having an inner surface and an outer surface, the inner and outer surfaces being coaxial about the rotational axis; and (ii) a cage holding the magnet segments relative to each other in the arrangement, the cage comprising an interior portion, a first end, a second end, and at least one longitudinal outer portion, the interior portion being situated between the rotational axis and the inner surface of the arrangement and coaxially with the arrangement such that the inner surface of the arrangement is coupled to the interior portion of the cage and the magnet segments radially surround the interior portion, the first end of the cage being coupled to the interior portion and to the first ends of the magnet segments so as to hold the first ends of the magnet segments relative to each other in the arrangement, and the second end of the cage being coupled to the interior portion and to the second ends of the magnet segments so as to hold the second ends of the magnet segments relative to each other in the arrangement, the first and second ends of the cage being coupled together on the outer surface of the arrangement by the at least one longitudinal outer portion extending between the first and second ends substantially flush with the outer surface.    
   
   
       19 . The pump of  claim 18 , wherein: 
 the pump is a gear pump; and    the active pump-component comprises at least one gear.    
   
   
       20 . The pump of  claim 18 , wherein the active pump-component comprises a driving gear coupled to the driven-magnet assembly, and a driven gear interdigitated with the driving gear so as to rotate about its axis whenever the driving gear is caused to rotate about its axis by the driven-magnet assembly.  
   
   
       21 . The pump of  claim 18 , further comprising a rotating-magnetic-field device configured to be magnetically coupled to the driven-magnet assembly in a manner causing rotation of the driven-magnet assembly about its axis.  
   
   
       22 . The pump of  claim 21 , wherein the rotating-magnetic-field device comprises a stator that, when energized, produces a rotating magnetic field that is coupled to the driven-magnet assembly.  
   
   
       23 . The pump of  claim 22 , wherein: 
 the pump housing further comprises a magnet cup housing the driven-magnet assembly within the pump housing; and    the stator is situated in surrounding relationship coaxially with the driven-magnet assembly in the magnet cup, such that energization of the stator causes corresponding coaxial rotation of the driven-magnet assembly in the magnet cup.    
   
   
       24 . A driven-magnet assembly for a magnetically driven pump, the assembly comprising: 
 multiple magnet segments each having a first end, a second end, and lateral sides, the magnet segments being situated at respective positions around a rotational axis in an arrangement in which the magnet segments collectively define an inner surface and an outer surface of the arrangement, the inner and outer surfaces being coaxial about the rotational axis; and    a molded body holding the magnet segments relative to each other in the arrangement, the molded body comprising an interior portion, a first end, and a second end, the interior portion being situated between the rotational axis and the inner surface of the arrangement and coaxially with the arrangement such that the inner surface of the arrangement is coupled to the interior portion and the magnet segments radially surround the interior portion, the first end being coupled to the interior portion and to the first ends of the magnet segments so as to hold the first ends of the magnet segments relative to each other in the arrangement, and the second end being coupled to the interior portion and to the second ends of the magnet segments so as to hold the second ends of the magnet segments relative to each other in the arrangement, thereby leaving the outer surface of the arrangement substantially bare.    
   
   
       25 . The assembly of  claim 24 , wherein the molded body further comprises at least one longitudinal outer portion that is coupled to the first and second ends of the molded body and extends between the first and second ends substantially flush with the outer surface.  
   
   
       26 . The assembly of  claim 25 , wherein: 
 the magnet segments are situated side-by-side in the arrangement;    the molded body comprises multiple longitudinal outer portions;    each longitudinal outer portion extends along respective lateral sides of adjacent magnet segments.    
   
   
       27 . The assembly of  claim 24 , further comprising a flux ring having an inner surface and an outer surface, wherein the inner surface of the arrangement is coupled to the outer surface of the flux ring, and the inner surface of the flux ring is coupled to the interior portion of the cage.  
   
   
       28 . A driven-magnet assembly for a magnetically driven pump, the assembly comprising: 
 a magnet-flux-ring assembly comprising (i) a flux ring having an inner surface and an outer surface configured concentrically around a rotational axis and (ii) multiple magnet segments arranged at respective radial positions around the rotational axis, the magnet segments each having a respective inner surface, outer surface, first end, second end, and lateral sides, the inner surfaces being attached to the outer surface of the flux ring such that the magnet segments are arranged side-by-side around the flux ring, and the outer surfaces collectively form an outer surface of the magnet-flux-ring assembly; and    a molded body having an interior portion, a first end, and a second end, the interior portion being situated radially inwardly of, and attached to, the inner surface of the flux ring, the first end being integral with the interior portion and configured so as to capture the first ends of the magnet segments relative to the flux ring, the second end being integral with the interior portion and configured so as to capture the second ends of the magnet segments relative to the flux ring, the outer surface of the magnet-flux-ring assembly being substantially bare.    
   
   
       29 . The assembly of  claim 28 , wherein the molded body further comprises at least one longitudinal outer portion that is integral with the first and second ends and that extends between the first and second ends along respective lateral sides of adjacent magnet segments substantially flush with the outer surface of the magnet-flux-ring assembly.  
   
   
       30 . The assembly of  claim 29 , wherein: 
 the molded body comprises multiple longitudinal outer portions;    the lateral edges of the magnet segments include chamfers that define, in the magnet-flux-ring assembly, channels between adjacent magnet segments attached to the outer surface of the flux ring; and    the longitudinal outer portions are situated in the channels, substantially flush with the outer surface of the magnet-flux-ring assembly.    
   
   
       31 . The assembly of  claim 30 , wherein: 
 the lateral edges of adjacent magnet segments attached to the outer surface of the flux ring define respective voids extending radially from the outer surface of the magnet-flux-ring assembly to the outer surface of the flux ring; and    the molded body further comprises radial portions extending through the voids and coupling the longitudinal outer portions with the flux ring.    
   
   
       32 . The assembly of  claim 28 , wherein the interior portion of the molded body defines a bore extending along the rotational axis.  
   
   
       33 . The assembly of  claim 32 , further comprising a shaft seated in the bore, the shaft being configured to facilitate rotation of the driven-magnet assembly about the rotational axis.  
   
   
       34 . A pump, comprising: 
 a pump housing enclosing an active pump-component that, when rotated about an axis, generates a liquid-pumping force urging liquid to flow through the pump housing; and    a driven-magnet assembly for a magnetically driven pump, the assembly comprising (i) a magnet-flux-ring assembly comprising (a) a flux ring having an inner surface and an outer surface configured concentrically around a rotational axis and (b) multiple magnet segments arranged at respective radial positions around the rotational axis, the magnet segments each having a respective inner surface, outer surface, first end, second end, and lateral sides, the inner surfaces being attached to the outer surface of the flux ring such that the magnet segments are arranged side-by-side around the flux ring, and the outer surfaces collectively form an outer surface of the magnet-flux-ring assembly; and (ii) a molded body having an interior portion, a first end, and a second end, the interior portion being situated radially inwardly of, and attached to, the inner surface of the flux ring, the first end being integral with the interior portion and configured so as to capture the first ends of the magnet segments relative to the flux ring, the second end being integral with the interior portion and configured so as to capture the second ends of the magnet segments relative to the flux ring, the outer surface of the magnet-flux-ring assembly being substantially bare.    
   
   
       35 . A magnetically actuated gear pump, comprising: 
 a pump housing, comprising a pump cavity and a magnet cup;    a driving gear and a driven gear enclosed within the pump cavity, the driving gear being rotatable about a first axis, and the driven gear being interdigitated with the driving gear and being rotatable about a second axis; and    a driven-magnet assembly rotationally coupled to the driving gear, the driven-magnet assembly comprising (i) multiple magnet segments each having a first end, a second end, and lateral edges, the magnet segments being situated at respective positions around the first axis in an arrangement having an inner surface and an outer surface, the inner and outer surfaces being coaxial about the first axis; and (ii) a cage holding the magnet segments relative to each other in the arrangement, the cage comprising an interior portion, a first end, a second end, and at least one longitudinal outer portion, the interior portion being situated between the first axis and the inner surface of the arrangement and coaxially with the arrangement such that the inner surface of the arrangement is coupled to the interior portion of the cage and the magnet segments radially surround the interior portion, the first end of the cage being coupled to the interior portion and to the first ends of the magnet segments so as to hold the first ends of the magnet segments relative to each other in the arrangement, and the second end of the cage being coupled to the interior portion and to the second ends of the magnet segments so as to hold the second ends of the magnet segments relative to each other in the arrangement, the first and second ends of the cage being coupled together on the outer surface of the arrangement by the at least one longitudinal outer portion extending between the first and second ends substantially flush with the outer surface.    
   
   
       36 . The gear pump of  claim 35 , further comprising a stator situated coaxially surrounding the magnet cup such that energization of the stator causes the stator to produce a magnetic field rotating about the first axis, the rotating magnetic field produced by the stator being magnetically coupled through the magnet cup to the driven-magnet assembly so as to cause corresponding rotation of the driven-magnet assembly about the first axis.  
   
   
       37 . A magnetically actuated gear pump, comprising: 
 a pump housing, comprising a pump cavity and a magnet cup;    a driving gear and a driven gear enclosed within the pump cavity, the driving gear being rotatable about a first axis, and the driven gear being interdigitated with the driving gear and being rotatable about a second axis; and    a driven-magnet assembly rotationally coupled to the driving gear, the driven-magnet assembly comprising (i) multiple magnet segments each having a first end, a second end, and lateral sides, the magnet segments being situated at respective positions around the first axis in an arrangement in which the magnet segments collectively define an inner surface and an outer surface of the arrangement, the inner and outer surfaces being coaxial about the first axis; and (ii) a molded body holding the magnet segments relative to each other in the arrangement, the molded body comprising an interior portion, a first end, and a second end, the interior portion being situated between the first axis and the inner surface of the arrangement and coaxially with the arrangement such that the inner surface of the arrangement is coupled to the interior portion and the magnet segments radially surround the interior portion, the first end being coupled to the interior portion and to the first ends of the magnet segments so as to hold the first ends of the magnet segments relative to each other in the arrangement, and the second end being coupled to the interior portion and to the second ends of the magnet segments so as to hold the second ends of the magnet segments relative to each other in the arrangement, thereby leaving the outer surface of the arrangement substantially bare.    
   
   
       38 . The gear pump of  claim 37 , further comprising a stator situated coaxially surrounding the magnet cup such that energization of the stator causes the stator to produce a magnetic field rotating about the first axis, the rotating magnetic field produced by the stator being magnetically coupled through the magnet cup to the driven-magnet assembly so as to cause corresponding rotation of the driven-magnet assembly about the first axis.  
   
   
       39 . A magnetically actuated gear pump, comprising: 
 a pump housing, comprising a pump cavity and a magnet cup;    a driving gear and a driven gear enclosed within the pump cavity, the driving gear being rotatable about a first axis, and the driven gear being interdigitated with the driving gear and being rotatable about a second axis; and    a driven-magnet assembly rotationally coupled to the driving gear, the driven-magnet assembly comprising (i) a magnet-flux-ring assembly comprising (a) a flux ring having an inner surface and an outer surface configured concentrically around a rotational axis and (b) multiple magnet segments arranged at respective radial positions around the rotational axis, the magnet segments each having a respective inner surface, outer surface, first end, second end, and lateral sides, the inner surfaces being attached to the outer surface of the flux ring such that the magnet segments are arranged side-by-side around the flux ring, and the outer surfaces collectively form an outer surface of the magnet-flux-ring assembly; and (ii) a molded body having an interior portion, a first end, and a second end, the interior portion being situated radially inwardly of, and attached to, the inner surface of the flux ring, the first end being integral with the interior portion and configured so as to capture the first ends of the magnet segments relative to the flux ring, the second end being integral with the interior portion and configured so as to capture the second ends of the magnet segments relative to the flux ring, the outer surface of the magnet-flux-ring assembly being substantially bare.    
   
   
       40 . The gear pump of  claim 39 , further comprising a stator situated coaxially surrounding the magnet cup such that energization of the stator causes the stator to produce a magnetic field rotating about the first axis, the rotating magnetic field produced by the stator being magnetically coupled through the magnet cup to the driven-magnet assembly so as to cause corresponding rotation of the driven-magnet assembly about the first axis.  
   
   
       41 . In a magnetically driven gear pump, a driven-magnet assembly, comprising: 
 a flux ring configured as a hollow cylinder having a rotational axis, an outer surface, and an inner surface;    at least four magnet segments each having a first end, a second end, lateral edges, an outer-radius surface, and an inner-radius surface and each producing a respective magnetic field that is either directed radially inwardly or radially outwardly, the inner-radius surfaces of the magnet segments being mounted to the outer surface of the flux ring such that the magnet segments collectively form a radial arrangement of magnet segments around the axis of rotation, the outer-radius surfaces of the magnet segments collectively form an outer surface of the radial arrangement, and the respective magnetic fields alternate in direction from one magnet segment to the next around the flux ring; and    a non-magnetic cage holding the magnet segments relative to each other in the arrangement, the cage comprising an interior portion attached coaxially to the inner surface of the flux ring, a first end integral with the interior portion and attached to the first ends of the magnet segments in the arrangement, a second end integral with the interior portion and attached to the second ends of the magnet segments in the arrangement, and at least one longitudinal outer portion integral with and extending, parallel to the rotational axis, from the first to the second ends of the cage on the outer surface of the arrangement, substantially flush with the outer surface.    
   
   
       42 . The assembly of  claim 41 , wherein the cage is molded in situ to the flux ring and magnet segments.  
   
   
       43 . The assembly of  claim 41 , wherein the cage is molded of plastic.  
   
   
       44 . The assembly of  claim 41 , wherein: 
 the inner-radius surfaces of the magnet segments are bonded to the outer surface of the flux ring; and    lateral edges of adjacent magnet segments are bonded together in the arrangement.    
   
   
       45 . The assembly of  claim 41 , wherein: 
 the lateral edges of the magnet segments have respective chamfers that define channels between adjacent magnet segments in the arrangement;    the cage comprises multiple longitudinal outer portions; and    the longitudinal outer portions are situated in the channels, substantially flush with the outer surface of the arrangement.    
   
   
       46 . The assembly of  claim 41 , wherein: 
 the lateral edges of adjacent magnet segments of the arrangement define respective voids extending radially from the outer surface of the arrangement to the outer surface of the flux ring; and    the cage includes radial portions extending through the voids and coupling the longitudinal outer portions of the cage with the flux ring.    
   
   
       47 . The assembly of  claim 46 , wherein the radial portions are coupled to the longitudinal outer portions at substantially mid-length of the longitudinal outer portions.  
   
   
       48 . The assembly of  claim 41 , wherein: 
 the first end of the cage is configured to capture the first ends of the magnet segments together circumferentially; and    the second end of the cage is configured to capture the second ends of the magnet segments together circumferentially.    
   
   
       49 . The assembly of  claim 41 , wherein: 
 the ends of the magnet segments have respective stepped profiles that define radial channels between adjacent magnet segments in the arrangement; and    at least one of the first and second ends of the cage comprises radial portions that fill respective radial channels.    
   
   
       50 . The assembly of  claim 41 , further comprising a rotational coupling of the driven-magnet assembly to a driving gear, the coupling being configured such that rotation of the driven-magnet assembly about the rotational axis causes corresponding rotation of the driving gear about the rotational axis.  
   
   
       51 . The assembly of  claim 50 , wherein the rotational coupling comprises a bore defined in the second end of the cage that is configured to receive a complementarily shaped shaft of the driving gear.  
   
   
       52 . A gear pump, comprising: 
 a pump housing defining a pump cavity and a magnet cup having an axis;    a driving gear meshed with a driven gear in the pump cavity;    a driven-magnet assembly, configured as recited in  claim 42 , situated coaxially inside the magnet cup and coupled to the driving gear such that rotation of the driven-magnet assembly about the axis causes corresponding rotation of the driving gear about the axis.    
   
   
       53 . The gear pump of  claim 52 , further comprising a stator situated outside but coaxially with the magnet cup so as to cause rotation of the driven-magnet assembly about the axis in the magnet cup whenever the stator is energized.  
   
   
       54 . A driven-magnet assembly for a magnetically driven pump, the assembly comprising: 
 magnet means for providing a sequentially alternating magnetic polarity around a rotational axis, the magnet means comprising multiple magnet segments having an inside surface, an outside surface, a first end, a second end, and lateral edges, the magnet segments being situated side-by-side and with sequentially alternating magnetic polarity around the rotational axis and the outside surfaces of the magnet segments collectively forming an outer surface of the magnet means; and    cage means, situated relative to the magnet means, for holding the inside surfaces of the magnet segments relative to each other and for capturing the first and second ends of the magnet segments relative to each other, during rotation of the driven-magnet assembly about the rotational axis, while leaving the outer surfaces of the magnet segments substantially bare.    
   
   
       55 . The driven-magnet assembly of  claim 54 , wherein the magnet means further comprises flux-ring means for shaping and concentrating respective magnetic fields produced by the magnet segments around the rotational axis.  
   
   
       56 . A hydraulic circuit, comprising: 
 a gear pump as recited in  claim 35;     a first conduit leading from the gear pump to a location; and    a second conduit leading from the location to the gear pump, wherein the gear pump urges flow of a liquid from the gear pump through the first conduit to the location and from the location through the second conduit to the gear pump.    
   
   
       57 . A hydraulic circuit, comprising: 
 a gear pump as recited in  claim 37;     a first conduit leading from the gear pump to a location; and    a second conduit leading from the location to the gear pump, wherein the gear pump urges flow of a liquid from the gear pump through the first conduit to the location and from the location through the second conduit to the gear pump.    
   
   
       58 . A hydraulic circuit, comprising: 
 a gear pump as recited in  claim 39;     a first conduit leading from the gear pump to a location; and    a second conduit leading from the location to the gear pump, wherein the gear pump urges flow of a liquid from the gear pump through the first conduit to the location and from the location through the second conduit to the gear pump.