Open coil electric heater assembly

Claim 1

An electric heater assembly for supporting a plurality of reaches of a sinuously formed helical resistance element, comprising: a heat resistant base, a thin metal plate secured to said base forming a rigid assembly therewith, said thin plate constituting the sole support for said element reaches adjacent thereto, said plate having a plurality of apertures therethrough and through which said reaches extend, said plate at the periphery of said apertures having a serrated configuration to define a plurality of tongues in circumferentially spaced relation extending radially inwardly of said apertures, said tongues when unstressed being disposed in the plane of said plate, and a plurality of rigid tubular heat resistant insulating bushings, each having a radial flange thereon, one surrounding each reach where the latter extends through a plate aperture thereby to insulate the reach from said plate, each said bushing having a diameter slightly greater than the diameter of said aperture measured between the radially innErmost extremities of said tongues when unstressed, each bushing fitting within and extending through a respective aperture thereby to stress and deflect said tongues in a common direction for radial gripping engagement with said bushing, said bushing radial flange abutting said plate in an axial direction and radially outwardly of said aperture at a point axially spaced from the point of tongue engagement with the bushing, said spaced axial and radial engagement of said plate with said bushing constituting the sole support of said bushing in said plate, thereby providing an effective, simple and stable support for said electric element reaches in said heater assembly.