POMPA SOMMERSA CON INVOLUCRO DI ESPANSO E METODO PER COSTRUIRLA

An expanded foam material surrounds a relatively thin, metallic motor casing and forms a housing which supports the motor while providing a seal to preclude leakage of liquids into the motor casing and to prevent discharge of dielectric oil from the interior of the motor casing. During manufacture of the pump, the casing is placed within a mold and a portion of the mold structure complementally and firmly engages four radially spaced regions of the generally cylindrical motor casing. Next, a quantity of the initially pourable foam material is introduced into the space between the mold and the casing, and the material self-expands to a solidified, cured condition in firm, surrounding engagement with the motor casing. The mold structure engaging the four regions of the casing consequently causes four radially spaced openings or windows to be formed which extend through the cured housing and expose the associated regions of the casing to the atmosphere, so that dissipation of heat from the motor is facilitated during operation of the pump. Curing of the foam material occurs at a relatively low temperature and pressure so that the housing may be molded around the casing in direct contact with the same without damage to the internal motor components.