Linear induction motor

Claim 2

A linear induction motor comprising a primary member and a secondary member spaced apart with a single planar air gap therebetween, said primary member comprising magnetic material and winding means formed on said magnetic material and arranged, when energised from an alternating current supply, for creating a field of magnetomotive force which travels longitudinally of the motor, said secondary member comprising electrically conductive material, said primary and secondary members being arranged and disposed transversely of the motor to provide in combination a first plurality of flux paths which are orientated transversely of the motor and a second plurality of flux paths which are orientated longitudinally of the motor, in operation flux driven around the flux paths of both pluralities by the winding means inducing in the electrically conductive material currents which react with that flux to produce a longitudinally directed force between the primary and secondary members.

Claim 3

A lInear induction motor comprising a primary member and a secondary member spaced apart with a single planar air gap therebetween, said primary member having magnetic material comprising a first part and a second part and winding means formed on said first part and arranged, when energised from an alternating current supply, for creating a field of magnetomotive force which travels longitudinally of the motor, said secondary member comprising electrically conductive material, said primary and secondary members being arranged and disposed transversely of the motor to provide in combination a first plurality of flux paths which are orientated transversely of the motor, and a second plurality of flux paths which are orientated longitudinally of the motor, the flux paths of one of said plurality being provided in part by the said first part of the primary member magnetic material and in part by the said second part thereof, the flux paths of the other said plurality being provided in part by only the first part of the primary member magnetic material, in operation flux driven around the flux paths of both pluralities by the winding means inducing in the electrically conductive material currents which react with that flux to produce a longitudinally directed force between the primary and secondary members.

Claim 4

A lInear induction motor comprising a primary member and a secondary member spaced apart with a single planar air gap therebetween, said primary member having magnetic material comprising a first part and a second part and winding means formed on said first part and arranged, when energised from an alternating current supply, for creating a field of magnetomotive force which travels longitudinally of the motor, said secondary member comprising electrically conductive material, said primary and secondary members being arranged and disposed transversely of the motor to provide in combination a first plurality of flux paths which are orientated transversely of the motor, and a second plurality of flux paths which are orientated longitudinally of the motor, the flux paths of one of said plurality being provided in part by the said first part of the primary member magnetic material and in part by the said second part thereof, the flux paths of the other said plurality being provided in part by only the first part of the primary member magnetic material, in operation flux driven around the flux paths of both pluralities by the winding means inducing in the electrically conductive material currents which react with that flux to produce a longitudinally directed force between the primary and secondary members.

Claim 5

A linear induction motor comprising a primary member and a secondary member spaced apart with a single planar air gap therebetween, said primary member having magnetic material comprising a first part formed of at least one stack of magnetic laminations and a second part, and winding means formed on said first part and arranged, when energised from an alternating current supply, for creating a field of magnetomotive force which travels longitudinally of the motor, said secondary member comprising electrically conductive material, said primary and secondary members being arranged and disposed transversely of the motor to provide in combination a first plurality of flux paths which are orientated transversely of the motor and which pass through said electrically conductive material, and a second plurality of flux paths which are orientated longitudinally of the motor and which also pass through said electrically conductive material, the flux paths of one said plurality being provided in part by said first part of the primary member magnetic material and in part by the said second part thereof, the flux paths of the other said plurality being provided in part by only the said first part of the primary member magnetic material, in operation flux driven around the flux paths of both pluralities by the winding means inducing in the electrically conductive material currents which react with that flux to produce a longitudinally directed force between the primary and secondary members.

Claim 6

A linear induction motor comprising a primary member and a secondary member spaced apart with a single planar air gap therebetween, said primary member having magnetic material comprising a first part formed of at least one stack of magnetic laminations and a second part, and winding means formed on said first part and arranged, when energised from an alternating current supply, for creating a field of magnetomotive force which travels longitudinally of the motor, said secondary member comprising electrically conductive material, said primary and secondary members being arranged and disposed transversely of the motor to provide in combination a first plurality of flux paths which are orientated transversely of the motor and which pass through said electrically conductive material, and a second plurality of flux paths which are orientated longitudinally of the motor and which also pass through said electrically conductive material, the flux paths of one said plurality being provided in part by said first part of the primary member magnetic material and in part by the said second part thereof, the flux paths of the other said plurality being provided in part by only the said first part of the primary member magnetic material, in operation flux driven around the flux paths of both pluralities by the winding means inducing in the electrically conductive material currents which react with that flux to produce a longitudinally directed force between the primary and secondary members.

Claim 7

A linear induction motor comprising a primary member and a secondary member spaced apart with a single planar air gap therebetween, said primary member having magnetic material comprising a first part formed of at least one stack of magnetic laminations each orientated longitudinally of the motor and a second part formed of magnetic laminations each orientated transversely of the motor, and winding means formed on one of said parts and arranged, when energised from an alternating current supply, for creating a field of magnetomotive force which travels longitudinally of the motor, said secondary member comprising electrically conductive material, said primary and secondary members being arranged and disposed transversely of the motor to provide in combination a first plurality of flux paths which are orientated transversely of the motor and which pass through said electrically conductive material, and a second plurality of flux paths which are orientated longitudinally of the motor and which also pass through said electrically conductive material, the flux paths of one said plurality being provided in part by the said first part of the primary member magnetic material and in part by the said seCond part thereof, the flux paths of the other said plurality being provided in part by only the said part of the primary member magnetic material which is formed with the winding means, in operation flux driven around the flux paths of both pluralities by the winding means inducing in the electrically conductive material currents which react with that flux to produce a longitudinally directed force between the primary and secondary members.

Claim 8

A linear induction motor comprising a primary member and a secondary member spaced apart with a single planar air gap therebetween, said primary member having magnetic material comprising a first part formed of at least one stack of magnetic laminations each orientated longitudinally of the motor and a second part formed of magnetic laminations each orientated transversely of the motor, and winding means formed on one of said parts and arranged, when energised from an alternating current supply, for creating a field of magnetomotive force which travels longitudinally of the motor, said secondary member comprising electrically conductive material, said primary and secondary members being arranged and disposed transversely of the motor to provide in combination a first plurality of flux paths which are orientated transversely of the motor and which pass through said electrically conductive material, and a second plurality of flux paths which are orientated longitudinally of the motor and which also pass through said electrically conductive material, the flux paths of one said plurality being provided in part by the said first part of the primary member magnetic material and in part by the said seCond part thereof, the flux paths of the other said plurality being provided in part by only the said part of the primary member magnetic material which is formed with the winding means, in operation flux driven around the flux paths of both pluralities by the winding means inducing in the electrically conductive material currents which react with that flux to produce a longitudinally directed force between the primary and secondary members.

Claim 9

A linear induction motor according to claim 3, wherein the first part of the primary member magnetic material comprises a plurality of lamination stacks which are spaced apart longitudinally of the motor and which are formed with the winding means, each lamination stack being formed of transversely orientated laminations and having at least two transversely spaced limbs extending towards the secondary member, the second part of the primary member magnetic material being arranged magnetically to bridge the said spaces between the lamination stacks.

Claim 10

A linear induction motor according to claim 5, wherein the second part of the primary member magnetic material comprises discrete portions each disposed to extend between the opposed faces of successive ones of the lamination stacks.

Claim 11

A linear induction motor according to claim 5, wherein the second part of the primary member magnetic material extends continuously along the primary member adjacent the lamination stacks.

Claim 12

A linear induction motor according to claim 5, wherein the secondary member includes magnetic material formed of transversely orientated magnetic laminations arranged to provide further parts of the flux paths of each said plurality.

Claim 13

A linear induction motor according to claim 2, wherein the first part of the primary member magnetic material extends continuously along the primary member and has its face opposed to the secondary member formed with longitudinally spaced winding slots in which are received the winding conductors of the winding means, the first part of the primary member magnetic material providing part of the flux paths of the said second plurality and the second part of the primary member magnetic material extending transversely of the motor from the said first part to provide, in combination with the said first part, a least part of the flux paths of said first plurality.

Claim 14

A linear induction motor according to claim 9, wherein the first part of the primary member magnetic material is dimensioned to saturate at a low level of flux where it bridges the winding slots.

Claim 15

A linear induction motor according to claim 9, which includes two said first parts of the primary member magnetic material spaced transversely apart by a gap which is magnetically bridged by the said second part of the primary member magnetic material, the winding means of the two said first parts being energisable to produce travelling fields of magnetomotive force which are substantially in antiphase with one another transversely of the motor.

Claim 16

A linear induction motor according to claim 9, wherein the second part of the primary member magnetic material extends transversely of the motor from either side of the first part to provide, in combination with the first part, part of the flux paths of two said first pluralities side-by-side across the width of the motor.

Claim 17

A linear induction motor according to claim 11, wherein the said first parts of the primary member magnetic material are arranged side-by-side with their said faces formed with the winding slots generally coplanar and facing in the same direction, and the secondary member comprises a generally plate-like member of electrically conductive material generally parallel to the plane of said faces, and further magnetic material adjacent the side of the said member remote from the primary member for providing part of the flux paths of the first and second pluralities.

Claim 18

A linear induction motor according to claim 11, wherein the second part of the primary member magnetic material is generaLly U-shaped in cross-section having two generally parallel arms, and the two said first parts of the primary member magnetic material are carried by respective ones of the arms of the insides thereof so as to oppose one another in spaced relationship at their said faces formed with the winding slots, the secondary member being constituted by said electrically conductive material which extends between the opposed faces in spaced relation thereto.

Claim 19

A linear induction motor as claimed in claim 1 in combination with a vehicle which carries the primary member and a prepared track along which the vehicle is arranged for operation and which carries the secondary member, the primary and secondary members being arranged for co-operation to propel the vehicle along the track.