appliance, rotor and magnet element

Abstract

A magnet element ( 37 ) and a method of its manufacture for assembly into a rotor ( 38 ), the magnet element ( 37 ) having magnetic domains aligned anisotropically to form a domain alignment pattern ( 42 ), wherein the magnetic domain alignment pattern ( 42 ) in the magnet element ( 37 ) has an orientation that varies substantially continuously across at least part of the magnet element ( 37 ) between its lateral edges from at least partially radial to at least partially tangential.

1 . A rotor comprising:
 a plurality of magnet elements with two lateral edges each with magnetic domains aligned anisotropically to form a domain alignment pattern, the plurality of magnets being arranged to form a permanent magnet ring with an inner face and an outer face, said permanent magnet ring being between 150 mm and 400 mm in diameter, less than 100 mm in height and less than 20 mm thick, and   a rigid support holding said magnet elements in said ring arrangement,   wherein the magnetic domain alignment pattern in each magnet element has an orientation that varies substantially continuously across at least part of the magnet element between its lateral edges from an orientation that has a predominant radial component at a pole of the magnet element to an orientation that has a least some tangential component at one lateral edge of the magnet element,   wherein the magnet elements are magnetised to produce a resulting magnetic flux field.   
     
     
         2 . (canceled) 
     
     
         3 . A rotor according to  claim 1  wherein each magnet element has the pole positioned between the magnet element's lateral edges and the magnetic domain alignment pattern in each magnet element has an orientation that varies substantially continuously across the width of the magnet element from an orientation that has a predominant radial component at the pole of the magnet element to an orientation that has a least some tangential component at both lateral edges of the magnet element. 
     
     
         4 . (canceled) 
     
     
         5 . A rotor according to  claim 3  wherein at both lateral edges the orientation of the magnetic domain alignment pattern has a significant tangential component, and the significant tangential component results in the magnetic domain alignment pattern having an orientation of at least 15 degrees, with respect to the lateral edges. 
     
     
         6 - 10 . (canceled) 
     
     
         11 . A rotor according to  claim 1  wherein the radial and tangential components of the orientation of the magnetic domain alignment pattern within the magnet element varies sinusoidally according to:
     V   R =cos(θ), and
 
     V   T =sin(θ)
 
 
       Where V R  and V T  are the radial and tangential components of the orientation respectively and θ is the angular position across the magnet element, varying from substantially −90 degrees at one lateral edge to substantially +90 degrees at the opposite lateral edge. 
     
     
         12 - 15 . (canceled) 
     
     
         16 . A rotor according to  claim 1  wherein the resulting magnetic flux field has poles with alternating polarity spaced around the ring, the poles being aligned radially with respect to the permanent magnet ring, and wherein the resulting magnetic flux field of the permanent magnet ring traverses between adjacent poles of opposite polarities and between those poles is focused to extend beyond the boundary defined by the inner face, but remain at least partially constrained within the boundary defined by the outer face of the permanent magnet ring. 
     
     
         17 . (canceled) 
     
     
         18 . A rotor according to  claim 16  wherein the portion of the resulting magnetic flux field in each magnet element has an orientation that varies substantially continuously over the magnet element wherein:
 across the width of the magnet element, the orientation varies from an orientation that has a predominant radial component at the pole to an orientation that has a predominant tangential component at the edges of the magnet element adjacent other magnet elements in the permanent magnet ring, and 
 across the depth of the magnet element, the orientation varies from an orientation that has a predominant radial component at an edge corresponding to the inner face of the permanent magnet ring to an orientation that has a predominant tangential component at an edge corresponding to the outer face of the permanent magnet ring. 
 
     
     
         19 - 23 . (canceled) 
     
     
         24 . A rotor according to  claim 1  wherein for each magnet element, the magnetic domains were aligned during production using a press or injection moulding tool comprising one or more elements defining a cavity, and an apparatus for applying a magnetic flux field, wherein the apparatus produces a magnetic field in the cavity similar in nature to the desired magnetic domain alignment pattern in the element. 
     
     
         25 . A rotor according to  claim 1  wherein the rotor is utilised in the drive motor of a washing machine comprising an electronically commutated motor, a stator of the motor having windings energisable to cause rotation of the rotor, said stator being coupled to a non-rotating tub or housing of the washing machine, said rotor being coupled to a rotating drum of the washing machine. 
     
     
         26 - 29 . (canceled) 
     
     
         30 . A motor for use in a washing machine, said motor comprising:
 a stator having at least three phase windings, each phase winding being formed on a plurality of radially extending stator teeth,
 a rotor as defined in any preceding claim, concentric with said stator with the permanent magnet ring outside said stator teeth and said rotor poles facing the ends of said stator teeth. 
   
     
     
         31 . A method of producing a rotor comprising the steps of:
 producing a plurality of magnet elements comprising permanent magnet material with two lateral edges each with magnetic domains aligned anisotropically to form a domain alignment pattern, wherein the magnetic domain alignment pattern in each magnet element has an orientation that varies substantially continuously across at least part of the magnet element between its lateral edges from an orientation that has a predominant radial component at a pole of the magnet element to an orientation that has a least some tangential component at one lateral edge of the magnet element,   arranging and retaining the magnet elements into a permanent magnet ring in a rigid support, and   magnetising the magnet elements to produce a resulting magnetic flux field.   
     
     
         32 . (canceled) 
     
     
         33 . A method according  claim 31  wherein the step of producing the plurality of magnet elements comprises applying an external magnetic flux field to each magnet element to align the magnetic domains. 
     
     
         34 . A method according to  claim 31  wherein each magnet element has the pole positioned between the magnet element's lateral edges and applying the external magnetic flux field to a magnet element aligns its magnetic domains such that the magnetic domain alignment pattern in the magnet element has an orientation that varies substantially continuously across the width of the magnet element from an orientation that has a predominant radial component at the pole of the magnet element to an orientation that has a least some tangential component at both lateral edges of the magnet element. 
     
     
         35 . (canceled) 
     
     
         36 . A method according to  claim 34  wherein at both lateral edges the orientation of the magnetic domain alignment pattern has a significant tangential component, and the significant tangential component results in the magnetic domain alignment pattern having an orientation of at least 15 degrees, with respect to the lateral edges. 
     
     
         37 - 40 . (canceled) 
     
     
         41 . A method according to  claim 31  wherein the radial and tangential components of the orientation of the magnetic domain alignment pattern within the magnet element varies sinusoidally according to:
     V   R =cos(θ), and
 
     V   T =sin(θ)
 
 
       Where V R  and V T  are the radial and tangential components of the orientation respectively and θ is the angular position across the magnet element, varying from substantially −90 degrees at one lateral edge to substantially +90 degrees at the opposite lateral edge. 
     
     
         42 - 50 . (canceled) 
     
     
         51 . A rotor comprising:
 a plurality of magnet elements with two lateral edges each with magnetic domains aligned anisotropically to form a domain alignment pattern, the plurality of magnets being arranged to form a permanent magnet arrangement, and   a rigid support holding said magnet elements in said arrangement,   wherein the magnetic domain alignment pattern in each magnet element has an orientation that varies substantially continuously across at least part of the magnet element between its lateral edges from an orientation that has a predominant radial component at a pole of the magnet element to an orientation that has a least some tangential component at one lateral edge of the magnet element,   wherein the magnet elements are magnetised to produce a resulting magnetic flux field.   
     
     
         52 . A magnet element for assembly into a ring of magnet elements to form part of a rotor, the magnet element having two lateral edges each with magnetic domains aligned anisotropically to form a domain alignment pattern, wherein the magnetic domain alignment pattern in the magnet element has an orientation that varies substantially continuously across at least part of the magnet element between its lateral edges from an orientation that has a predominant radial component at a pole of the magnet element to an orientation that has a least some tangential component at one lateral edge of the magnet element. 
     
     
         53 . (canceled) 
     
     
         54 . A magnet element according to  claim 52  wherein the pole is positioned between the magnet element's lateral edges and the magnetic domain alignment pattern in each magnet element has an orientation that varies substantially continuously across the width of the magnet element from an orientation that has a predominant radial component at the pole of the magnet element to an orientation that has a least some tangential component at both lateral edges of the magnet element. 
     
     
         55 . (canceled) 
     
     
         56 . A magnet element according to  claim 54  wherein at both lateral edges the orientation of the magnetic domain alignment pattern has a significant tangential component, wherein the significant tangential component results in the magnetic domain alignment pattern having an orientation of at least 15 degrees, with respect to the lateral edges. 
     
     
         57 - 61 . (canceled) 
     
     
         62 . A magnet element according to  claim 52  wherein the radial and tangential components of the orientation of the magnetic domain alignment pattern within the magnet element varies sinusoidally according to:
     V   R =cos(θ), and
 
     V   T =sin(θ)
 
 
       Where V R  and V T  are the radial and tangential components of the orientation respectively and θ is the angular position across the magnet element, varying from substantially −90 degrees at one lateral edge to substantially +90 degrees at the opposite lateral edge. 
     
     
         63 - 81 . (canceled) 
     
     
         82 . A rotor according to  claim 51  wherein for each magnet element, the magnetic domains were aligned during production using a press or injection moulding tool comprising one or more elements defining a cavity, and an apparatus for applying a magnetic flux field, wherein the apparatus produces a magnetic field in the cavity similar in nature to the desired magnetic domain alignment pattern in the element. 
     
     
         83 . An appliance with a drive motor, the drive motor comprising a stator, and a rotor according to  claim 1 . 
     
     
         84 . A rotor according to  claim 3  wherein at both lateral edges the orientation of the magnetic domain alignment pattern has a significant tangential component, and the significant tangential component results in the magnetic domain alignment pattern having an orientation of at between 20 to 35 degrees, with respect to the lateral edges. 
     
     
         85 . A rotor according to  claim 3  wherein at both lateral edges the orientation of the magnetic domain alignment pattern has a significant tangential component, and the significant tangential component results in the magnetic domain alignment pattern having an orientation of substantially 30 degrees, with respect to the lateral edges. 
     
     
         86 . A method according to  claim 34  wherein at both lateral edges the orientation of the magnetic domain alignment pattern has a significant tangential component, and the significant tangential component results in the magnetic domain alignment pattern having an orientation of between 20 degrees and 35 degrees, with respect to the lateral edges. 
     
     
         87 . A method according to  claim 34  wherein at both lateral edges the orientation of the magnetic domain alignment pattern has a significant tangential component, and the significant tangential component results in the magnetic domain alignment pattern having an orientation of substantially 30 degrees, with respect to the lateral edges. 
     
     
         88 . A magnet element according to  claim 54  wherein at both lateral edges the orientation of the magnetic domain alignment pattern has a significant tangential component, wherein the significant tangential component results in the magnetic domain alignment pattern having an orientation of between 20 degrees to 35 degrees, with respect to the lateral edges. 
     
     
         89 . A magnet element according to  claim 54  wherein at both lateral edges the orientation of the magnetic domain alignment pattern has a significant tangential component, wherein the significant tangential component results in the magnetic domain alignment pattern having an orientation of substantially 30 degrees, with respect to the lateral edges.