Self-insulating stator structure for novel d.c. brushless motors

Description
Self-insulating stator structure for novel d.c. brushless motors consists of injection molded components in Rynite® PET thermoplastic polyester resin. The motor's patented design eliminates or greatly reduces the need for iron cores, allowing use of simple, inexpensive electronic controls. It also provides exceptional efficiency.

Target applications include washing machines, vacuum cleaners, HVAC fans and blowers, golf carts, disability vehicles, pumps, garage door openers, hospital beds and alternators.

Benefits
Lower cost. The stator structure in Rynite®, one piece for smaller motors, two for larger units, reduces both part and assembly costs. It eliminates the need for separate insulating components and incorporates integral winding posts and termination features. Thanks to this and other design innovations, total manufacturing costs are about one-third less than variable-speed a.c. induction motors or half as much as conventional d.c. brushless motors, according to Wellington Drive Technologies.

Higher efficiency. Wellington Drive's data show that the motors reach 85 to 95% efficiency at 60 to 80% load. Most electronic motors achieve their maximum efficiency of 75 to 80% only at full load.

Light weight. These motors weigh less than half as much as comparable a.c. induction motors, thanks to the stator in Rynite® and to 'coreless' construction.

Electrical compliance. For the motors shown, stator components in Rynite® are part of a Class F (155°C) insulation system (UL 1446). The material can be used for systems up to Class N (200°C).

Materials Used
Rynite® PET fulfills the following key requirements for the stator: high temperature resistance; superior stiffness and strength; dimensional stability; low creep; recognition by electrical authorities throughout the world; and high productivity in injection molding.

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