Synchronous electric motor

Claim 2

A synchronous electric motor comprising a casing, at least a pair of axially spaced annular core members fixed within said casing, field winding means disposed between said core members for establishing a closed DC magnetic field extending axially within said casing and passing radially through said core members and circumferentially of the casing for establishing a rotating field within said casing, a rotor journaled in said casing concentrically of said core members and said winding means, said rotor including a shaft, squirrel cage winding means fixed to said shaft and including circumferentially spaced electrically conducting rods and remote end plates disposed in planes substantially straddling said core members, and a pair of pole pieces within the confines of said squirrel cage winding means and having radially projecting poles pierced by some said rods; and means for exciting said field windings to establish magnetic lock between said poles and the rotating polyphase field after said rotor has been started by asynchronous inductive interaction between said rotating polyphase field and said squirrel cage windings.

Claim 3

A synchronous electric motor comprising a casing, at least a pair of axially spaced annular core members fixed within said casing, field winding means disposed between said core members for establishing a closed DC magnetic field extending axially within said casing and passing radially through said core members, and polyphase winding means extending through said core members and circumferentially of the casing for establishing a rotating field within said casing, a rotor journaled in said casing concentrically of said core members and said winding means, said rotor comprising a shaft, a first pair of electrically conductive end plates surrounding said shaft in axially spaced relation and oriented in planes substantially straddling one of said core members, a first series of electrically conducting rods extending between and joining said first pair of end plates to form a first squirrel cage winding therewith, a second pair of end plates surrounding said shaft in axially spaced relation and orientated in planes substantially straddling the other of said core members, a second series of electrically conducting rods extending between and joining said second pair of end plates to form a second squirrel cage winding therewith, a spacer of material having good magnetic conductivity disposed between the adjacent end plates of said two squirrel cage windings, a first pole piece disposed between said first pair of end plates and having poles disposed adjacent said one core member, a second pole piece disposed between said second pair of end plates and having poles adjacent said other core member, the poles of the two pole pieces being disposed in circumferentially staggered radial planes with respect to the axis of said shaft, and means for exciting said field winding to establish magnetic lock between said poles and the rotating polyphase field after said rotor has been started by asynchronous inductive interaction between said rotating polyphase field and said squirrel cage windings.

Claim 4

A synchronous electric motor comprising a casing, at least a pair of axially spaced annular core members fixed within said casing, field winding means disposed between said core members for establishing a closed DC magnetic field extending axially within said casing and passing radially through said core members, and polyphase winding means extending through said core members and circumferentially of the casing for establishing a rotating field within said casing, a rotor journaled in said casing concentrically of said core members and said winding means, said rotor comprising a shaft, a first pair of electrically conductive end plates surrounding said shaft in axially spaced relation and oriented in planes substantially straddling one of said core members, a first series of electrically conducting rods extending between and joining said first pair of end plates to form a first squirrel cage winding therewith, a second pair of end plates surrounding said shaft in axially spaced relation and orientated in planes substantially straddling the other of said core members, a second series of electrically conducting rods extending between and joining said second pair of end plates to form a second squirrel cage winding therewith, a spacer of material having good magnetic conductivity disposed between the adjacent end plates of said two squirrel cage windings, a first pole piece disposed between said first pair of end plates and having poles disposed adjacent said one core member, a second pole piece disposed between said second pair of end plates and having poles adjacent said other core member, the poles of the two pole pieces being disposed in circumferentially staggered radial planes with respect to the axis of said shaft, and means for exciting said field winding to establish magnetic lock between said poles and the rotating polyphase field after said rotor has been started by asynchronous inductive interaction between said rotating polyphase field and said squirrel cage windings.

Claim 5

The synchronous motor as defined in claim 2 wherein said casing is provided with a third annular core member intermediate said pair of core members and of axial length substantially equal to the cumulative lengths of said pair of core members, and a second field winding is provided, the first field winding being disposed between one of said pair of core members and said third core member and the second field winding being disposed between the other of said pair of core members and said third core member, a third squirrel cage winding including a third pair of end plates disposed in planes substantially straddling said third core member circumferentially spaced rods joining said third pair of end plates, and a further pole piece disposed between said third pair of end plates and including poles adjacent said third core member and staggered with respect to the other of said poles.

Claim 6

A synchronous electric motor comprising a casing including opposite end shields, at least a pair of axially spaced annular core members fixed within said casing, field winding means disposed between said core members for establishing a closed DC magnetic field extending axially within said casing and passing radially through said core members for establishing a rotating field within said casing, a rotor journaled in said casing concentrically of said core members and said winding means, said rotor comprising a shaft having an enlarged intermediate portion of magnetic material and opposite end portions of nonmagnetic material projecting through and journaled in said shields, first and second squirrel cage windings and carried by said intermediate portion of the shaft, said first squirrel cage winding comprising a pair of axially spaced electrically conductive annular end plates disposed in planes straddling one of saiD core members and a series of uniformly spaced conducting bars joining such end plates, said second squirrel cage winding comprising a pair of axially spaced electrically conductive annular end plates disposed in planes straddling the other of said core members and a series of uniformly spaced conducting bars joining such end plates, first and second pole pieces respectively sandwiched between said first and second squirrel cage windings, each pole piece comprising a series of laminations, each of which includes an annular main body portion embracing said intermediate portion of the shaft and having circumferentially spaced radially projecting poles provided with openings receiving certain of said conducting bars, magnetically conducting spacer means disposed around said intermediate portion of the shaft between said squirrel cage windings and having an outer diameter substantially equal to the outer diameter of said main body portions of the laminations, and means for exciting said field winding to establish magnetic lock between said poles and the rotating polyphase field after said rotor has been started by asynchronous inductive interaction between said rotating polyphase field and said squirrel cage windings.

Claim 7

A synchronous electric motor comprising a casing including opposite end shields, at least a pair of axially spaced annular core members fixed within said casing, field winding means disposed between said core members for establishing a closed DC magnetic field extending axially within said casing and passing radially through said core members for establishing a rotating field within said casing, a rotor journaled in said casing concentrically of said core members and said winding means, said rotor comprising a shaft having an enlarged intermediate portion of magnetic material and opposite end portions of nonmagnetic material projecting through and journaled in said shields, first and second squirrel cage windings and carried by said intermediate portion of the shaft, said first squirrel cage winding comprising a pair of axially spaced electrically conductive annular end plates disposed in planes straddling one of saiD core members and a series of uniformly spaced conducting bars joining such end plates, said second squirrel cage winding comprising a pair of axially spaced electrically conductive annular end plates disposed in planes straddling the other of said core members and a series of uniformly spaced conducting bars joining such end plates, first and second pole pieces respectively sandwiched between said first and second squirrel cage windings, each pole piece comprising a series of laminations, each of which includes an annular main body portion embracing said intermediate portion of the shaft and having circumferentially spaced radially projecting poles provided with openings receiving certain of said conducting bars, magnetically conducting spacer means disposed around said intermediate portion of the shaft between said squirrel cage windings and having an outer diameter substantially equal to the outer diameter of said main body portions of the laminations, and means for exciting said field winding to establish magnetic lock between said poles and the rotating polyphase field after said rotor has been started by asynchronous inductive interaction between said rotating polyphase field and said squirrel cage windings.

Claim 8

The synchronous motor as defined in claim 4 wherein said main body portions of the laminations are notched to receive inner side portions of said conducting bars.

Claim 9

The synchronous motor as defined in claim 5 including spacer sleeves extending from the opposite ends of said intermediate portion of the shaft to said end shields.