Inner drive for magnetic drive pump

Abstract

An inner drive for a magnetic drive pump includes a magnet supported on a yoke. The inner drive is driven about an axis to pump a corrosive process fluid. The magnet and yoke are fully encapsulated during the molding process to completely surround the magnet and yoke in a protective plastic shell. A sleeve is arranged radially outwardly of the magnet to provide further protection. Backing rings are arranged on either side of the magnet. A bonding material joins the plastic shell to the backing rings and sleeve to prevent a space from forming beneath the plastic shell that would become filled with the process fluid once it has permeated the plastic shell. A protective coating is arranged on at least a portion of the magnet to further insulate the magnet from the process fluid.

1 . A magnetic driving element comprising: 
 a yoke;    a magnet supported on the yoke; and    a protective coating surrounding at least a portion of the magnet.    
   
   
       2 . The magnetic driving element according to  claim 1 , comprising a backing ring arranged radially outwardly of the yoke and axially adjacent to the magnet, the protective coating arranged between the backing ring and yoke and between the backing ring and magnet.  
   
   
       3 . The magnetic driving element according to  claim 2 , a backing ring is arranged on each of opposing sides of the magnet, the protective coating extending between opposing ends of the yoke beneath each backing ring.  
   
   
       4 . The magnetic driving element according to  claim 1 , wherein multiple magnets are arranged around an outer periphery of the yoke, the magnets forming gaps circumferentially between one another, with a potting material providing a fillet in the gaps between the magnets.  
   
   
       5 . The magnetic driving element according to  claim 4 , wherein a sleeve is arranged radially outwardly of the protective coating, and a plastic shell arranged radially outwardly of the sleeve, a potting material arranged in the gaps between the fillets and the sleeve.  
   
   
       6 . The magnetic driving element according to  claim 1 , wherein the protective powder coating is an epoxy blend.  
   
   
       7 . The magnetic driving element according to  claim 6 , the epoxy blend is a mixture of epoxy and polyester.  
   
   
       8 . A magnetic driving element comprising: 
 a magnet;    a metallic member arranged proximate to the magnet;    a plastic shell arranged proximate to the sleeve; and    a bonding material arranged between the plastic shell and metallic member joining the plastic shell and metallic member to one another.    
   
   
       9 . The magnetic driving element according to  claim 8 , wherein the metallic member is a sleeve arranged radially outwardly of the magnet, the bonding material adjoining the sleeve and the plastic shell.  
   
   
       10 . The magnetic driving element according to  claim 8 , wherein the metallic member is a backing ring arranged axially from the magnet, the bonding material adjoining at least one of the sleeve and backing rings and the plastic shell.  
   
   
       11 . The magnetic driving element according to  claim 8 , wherein the bonding material is a polymeric adhesive and fluoropolymer mixture.  
   
   
       12 . The magnetic driving element according to  claim 11 , wherein the fluoropolymer is provided by an ETFE powder.  
   
   
       13 . A magnetic driving element comprising: 
 a yoke;    a magnet supported on the yoke;    a plastic shell fully encapsulating the yoke and magnet with a continuous layer of molded material.    
   
   
       14 . The magnetic driving element according to  claim 13 , wherein an end of the yoke including a molding support surface for receiving a molding support during plastic molding of the shell.  
   
   
       15 . The magnetic driving element according to  claim 14 , wherein a protective coating covers at least a portion of the magnet and yoke, the protective coating extending to the molding support surface.  
   
   
       16 . The magnetic driving element according to  claim 13 , wherein the plastic shell contains at least one of an ETFE and PFA material.  
   
   
       17 . The magnetic driving element according to  claim 16 , wherein at least one of an ETFE and PFA materials contain reinforcing fibers.