Northern Engineering Industries Plc

Deryk S Gould

Michael T Wright

An induction motor with an improved torque/slip characteristic has a solid rotor having longitudinal grooves running parallel to the axis of rotation which connect with circumferential grooves at each end of the rotor. The rotor is plated with copper so that the grooves are filled with copper. The rotor is then machined over the cylindrical outer surface to produce a solid, non-laminated rotor having high-conductivity paths in the longitudinal grooves connected by high-conductivity short-circuiting rings in the circumferential grooves. In a modification the longitudinal grooves may be skewed. Other high conductivity material may replace copper, for example aluminium.

Induction motors

In a fluid-filled electric motor having a throughgoing shaft the requirements (i) internal fluid pressure maintained above ambient during installation (ii) equalization of internal and ambient pressures at run-up (iii) no solid particles contaminate internal fluid are met by a pressurizing apparatus in which internal motor pressure above ambient moves a piston against a spring. The pressure ensures integrity of a seal and pressure and temperature variations are accommodated by piston movement. The seal runs clear of the motor shaft allowing equalization of internal and ambient pressures during run up to speed. Only liquid can enter the spring chamber.

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Edinburgh, United Kingdom

Deryk S Gould