The present invention is directed to an electric motor which is adapted to be operated underwater and which is hereinafter referred to as a submersible electric motor. The present invention also relates to the method of manufacturing the submersible electric motor.
The canned-type submersible electric motor as shown in FIG. 1 is well-known in the art. The motor is comprised of a stator 1 having a stator core 2 and stator coils 5 and a rotor 9 having a rotor shaft 10 and a rotor core 11. The outer wall of the stator 1 is enclosed by a stainless steel tubular housing 101 and the inner wall of the stator 1 is covered by a thin stainless steel can 3. The ends of the annular space between the can and the housing in which the stator is located are sealed by means of flanges 102. The flanges 102 are supported by end brackets 12 and 13 which in turn support the shaft 10 for rotation through bearings 14 and 15. The thrust bearing 16 is supported by the end flange 13 and the interior of the can 3 is filled with a suitable antifreeze fluid for lubricating the thrust bearings 16. A terminal 7 is secured in the end flange 12 for connection with a power supply cable 8.
While the canned-type submersible electric motor construction is excellent in the insulation characteristic of the stator coils, such a construction is disadvantageous inasmuch as it is cumbersome and expensive. Since the motor needs the flanges 102 for sealing the ends of the housing 101 and the can 3, the interfitting portions of the ends of the housing 101 and can 3, the flanges 102 and the brackets 12 and 13 must be machined carefully and these components must be then assembled which results in a high manufacturing cost.