Linear induction motor

Claim 2

A polyphase linear induction motor comprising a primary member and a secondary member each having magnetic material arranged in combination to provide low reluctance paths which lie substantially in planes transverse to the motor, the primary member further comprising polyphase winding means formed on said primary member magnetic material and energizable from a polyphase alternating current supply to produce a field of magnetomotive force which travels longitudinally of the motor and which creates working magnetic flux in said low reluctance paths, said secondary member further comprising electrically conductive material disposed in the path of said working flux whereby currents induced therein by the working flux react with the working flux to produce a longitudinally directed force between the primary and secondary member, in each said low reluctance path said primary member terminating magnetically at two spaced end faces which face inwardly towards one another by an angle which is substantially less than two right angles, said secondary member correspondingly terminating in two end faces which face outwardly away from one another and which transversely of the motor are inclined to one another by the said angle, one of the said end faces of the secondary member being provided by the conductive material and the other end face being provided by the secondary member magnetic material.

Claim 3

An induction motor according to claim 1, wherein the primary and secondary member magnetic material is arranged in combination to provide the low reluctance paths side-by-side in pairs, the side-by-side low reluctance paths of each pair being provided in part by a common portion of the primary member magnetic material, the polyphase winding means being so arranged that working flux in the low reluctance paths of a pair passes in the same direction in the respective said common portion.

Claim 4

An induction motor according to claim 2, wherein the primary member magnetic material comprises a plurality of longitudinally spaced and generally E-shaped stacks of transverse laminations each having three limb portions, the secondary member magnetic material being formed of longitudinally arranged transverse laminations providing first and second longitudinally extending spaced outside-faces of the secondary member, and the conductive material providing a third outside-face of the secondary member between the first and second faces, the ends of the outer limb portions of the primary number magnetic material opposing respective ones of the first and second faces and the ends of the central limb portions opposing the said third face, the conductive material extending transversely of the motor beyond the center limb portions on either side thereof for providing parts of the conductive material current paths which extend longitudinally of the motor and are substantially free of working flux.

Claim 5

An induction motor according to claim 3, wherein the parts of the conductive material which extend transversely of the motor beyond the central limb portions of the primary member magnetic material are thicker than the part of the conductive material opposing the central limb portions.

Claim 6

An induction motor according to claim 2, wherein the primary member magnetic material comprises a plurality of longitudinally spaced and generally E-shaped stacks of transverse laminations, each lamination stack being formd of three generally parallel limb portions joined by a joke portion and having the ends of the outer limb portions extended beyond the end face of the center limb portion and turned inwardly so as to oppose one another in generally parallel relationship at their end faces, the polyphase winding means being disposed on at least the center ones of the limb portions, the secondary member magnetic material being formed of longitudinally arranged transverse laminations and providing first and second generally parallel and longitudinally extending outside faces of the secondary member and the conductive material providing a third outside face of the secondary member generally orthogonal to, and between, the first and second faces, the end of the outer limb portions of the primary magnetic material opposing respective ones of the first and second faces of the secondary member and the central limb portions opposing the third face thereof, the conductive material extending transversely of the motor beyond the central limb portions on either side thereof for providing parts of the conductive material current parts which extend longitudinally of the motor and which are substantially free of working flux.

Claim 7

An induction motor according to claim 5, wherein the polyphase winding means is disposed on all three limb portions of the lamination stacks of the primary member magnetic material.

Claim 8

A polyphase linear induction motor comprising a primary member and a secondary member each having magnetic material arranged in combination to provide low reluctance paths which lie substantially in planes transverse to the motor, the primary member further comprising polyphase winding means formed on said primary member magnetic material and energizable from a polyphase alternating current supply to produce a field of magnetomotive force which travels longitudinally of the motor and which creates working magnetic flux in said low reluctance paths, said secondary member further comprising electrically conductive material disposed in the path of said working flux whereby currents inducted therein by the working flux react with the working flux to produce a longitudinally directed force between the primary and secondary members, in each said low reluctance path said primary member terminating magnetically at two spaced end faces which face inwardly towards one another and which transversely of the motor are inclined to one another by an angle which is substantially less than two right angles, said secondary member correspondingly terminating in two end faces which face outwardly away from one another and which transversely of the motor are inclined to one another by the said angle, both of the said end faces of the secondary member being provided by the conductive material.

Claim 9

A polyphase linear induction motor comprising a primary member and a secondary member each having magnetic material arranged in combination to provide low reluctance paths which lie substantially in planes transverse to the motor, the primary member further comprising polyphase winding means formed on said primary member magnetic material and energizable from a polyphase alternating current supply to produce a field of magnetomotive force which travels longitudinally of the motor and which creates working magnetic flux in said low reluctance paths, said secondary member further comprising electrically conductive material disposed in the path of said working flux whereby currents inducted therein by the working flux react with the working flux to produce a longitudinally directed force between the primary and secondary members, in each said low reluctance path said primary member terminating magnetically at two spaced end faces which face inwardly towards one another and which transversely of the motor are inclined to one another by an angle which is substantially less than two right angles, said secondary member correspondingly terminating in two end faces which face outwardly away from one another and which transversely of the motor are inclined to one another by the said angle, both of the said end faces of the secondary member being provided by the conductive material.

Claim 10

An induction motor according to claim 7, wherein the conductive material extends continuously between the two said end faces and is formed at the intersection therebetween with a projection disposed in the path of flux which would otherwise pass directly between spaced parts of the primary member magnetic material.

Claim 11

An induction motor according to claim 7, wherein the primary and secondary member magnetic material is arranged in combiNation to provide the low reluctance paths side-by-side in pairs, the side-by-side low reluctance paths of each pair being provided in part by a common portion of the primary member magnetic material, the polyphase winding means being so arranged that working flux in the low reluctance paths of a pair passes in the same direction in the respective said common portion.

Claim 12

An induction motor according to claim 9, wherein the primary member magnetic material comprises a plurality of longitudinally spaced and generally E-shaped stacks of transverse laminations each having three limb portions, the conductive material being of generally channel-shaped cross section and the secondary member magnetic material being formed of longitudinally arranged transverse laminations received in the concavity defined by the conductive material, the conductive material providing at its outside first and second longitudinally extending spaced faces of the secondary member and also providing a third outside face of the secondary member between the first and second faces thereof the secondary member being disposed with its said first and second faces opposing the end faces of respective ones of the outer limb portions of the primary member magnetic material and with its said third face opposing the end faces of the central limb portions.

Claim 13

An induction motor according to claim 10, wherein the conductive material extends transversely of the motor beyond each limb portion of the primary member magnetic material for providing parts of the conductive material current parts which extend longitudinally of the motor and are substantially free of working flux.

Claim 14

An induction motor according to claim 11, wherein the said parts of the conductive material which extend transversely of the motor beyond each limb portion are thicker than the parts of the conductive material of the limb portions.

Claim 15

An induction motor according to claim 9, wherein the primary member magnetic material comprises a plurality of longitudinally spaced and generally C-shaped stacks of transverse laminations terminating magnetically in two end faces which face inwardly towards one another and which transversely of the motor are inclined to one another by one right angle, the conductive material being of generally L-shaped cross section and the secondary member magnetic material being formed of longitudinally arranged transverse laminations occupying the concavity defined by the conductive material, the conductive material providing at its outside first and second longitudinally extending and orthogonal outside faces of the secondary member which respectively oppose the two end faces of the said lamination stacks of the primary member magnetic material.

Claim 16

An induction motor according to claim 13, wherein the laminations of the secondary member magnetic material are generally right triangular, having their hypotenuse extending between the edges of the conductive material.