Expandable coil bracing tubes for electrical inductive apparatus

Claim 2

An electric inductive apparatus comprising, a casing, a magnetic core disposed within said casing, a winding support member axially surrounding said magnetic core, windings positioned on said winding support member, and, an expandable metallic, peripherially closed, tubular metallic, member positioned between said magnetic core and said winding support member, said metallic, member expanding in response to an increase in fluid pressure therein to provide a tight fitting relationship between said winding support member and said magnetic core.

Claim 3

The electric inductive apparatus of claim 1, wherein said magnetic core comprises a plurality of stacked metal laminations having a plurality of axial surfaces thereon, and, insulating means disposed between said axial surfaces of said magnetic core and said expandable, metallic, member, said insulating means preventing electrical contact between said magnetic core and said expandable, metallic, fluid-tight member.

Claim 4

The electric inductive apparatus of claim 1, wherein said magnetic core has a thin, evenly applied coating of insulating material thereon, said coating of insulating material being disposed between said magnetic core and said expandable, metallic, member, said insulating coating preventing electrical contact between said magnetic core and said expandable, metallic, fluid-tight member.

Claim 5

The electric inductive apparatus of claim 1, wherein said expandable, metallic, fluid-tight member is responsive to an increase of fluid pressure therein by expanding from a first preformed cross-section shape to an expanded second cross-section shape, said expandable, metallic, fluid-tight member in the expanded cross-section shape providing a tight fitting relationship between said magnetic core and said winding support member.

Claim 6

The electric inductive apparatus of claim 1, wherein: said magnetic core comprises a plurality of metal laminations stacked so as to provide said magnetic core with a cruciform cross-section, said magnetic core thereby having a plurality of discrete, stepped graduations disposed about the perimeter of said cruciform cross-section, saId magnetic core having a plurality of axial surfaces, said winding support member comprising a cylindrical winding tube, said winding tube axially surrounding said magnetic core, said winding tube contacting said magnetic core at a plurality of contact points along the interior surface of said winding tube, the interior surface of said winding tube and the axial surface of said magnetic core defining a plurality of void spaces which extend axially between the axial surfaces of said magnetic core and the interior surface of said winding tube, and said expandable, metallic, member being disposed to occupy at least one of the plurality of void spaces which extend axially between the axial surfaces of said magnetic core and the interior surface of said winding support member, insulating means disposed adjacent the axial surface of said magnetic core, said expandable, metallic, member being responsive to an increase in fluid pressure therein by expanding from a first preformed cross-section shape to a second expanded cross-section shape, said expandable, metallic, member in the second expanded cross-section shape abutting simultaneously said insulating means adjacent said magnetic core and the interior of said winding support member, said expandable, metallic, member thereby providing a tight fitting relationship between said winding support member and said magnetic core.