Smooth surface electric cooktop

Claim 2

A surface heating unit comprising a thin plate of glassceramic material supported on an aluminum plate, a metal sheathed heating element attached to the underside of the aluminum plate in a spiral form with an open central portion, a dished sheet metal reflector pan on which the aluminum plate is supported, and metallic spring means seated in the reflector pan and compressed against the central portion of the aluminum plate to maintain the aluminum plate flat against the glass-ceramic plate during the heating of the heating element to maintain maximum heat transfer beneath the heated aluminum plate and the glass-ceramic plate.

Claim 3

A surface heating unit as recited in claim 1 where the top surface of the aluminum plate is furnished with a high emissivity coating to be in contact with the glass-ceramic plate so as to assist the transfer of heat from the aluminum plate to the glass-ceramic plate as well as to prevent a reaction beTween the aluminum and the glass-ceramic material.

Claim 4

A surface heating unit comprising a plate of glass-ceramic material supported on an aluminum plate, a metal sheathed heating element arranged in a spiral configuration with an open central portion, said heating element being attached to the underside of the aluminum plate, a dished sheet metal reflector pan seated beneath the aluminum plate, and metallic spring means seated in the reflector pan and compressed against the underside of the aluminum plate to maintain the aluminum plate uniformly against the glass-ceramic plate during the heating of the heating element to maintain maximum heat transfer between the heated aluminum plate and the glass-ceramic aluminum plate, said metallic spring means being a strong sheet metal member with a planar top surface adapted to bear against the underside of the aluminum plate in the open central portion defined by the spiral heating element, said spring having a plurality of inclined support legs extending from beneath the top surface.

Claim 5

A surface heating unit comprising a plate of glass-ceramic material supported on an aluminum plate, a metal sheathed heating element arranged in a spiral configuration with an open central portion, said heating element being attached to the underside of the aluminum plate, a dished sheet metal reflector pan seated beneath the aluminum plate, and metallic spring means seated in the reflector pan and compressed against the underside of the aluminum plate to maintain the aluminum plate uniformly against the glass-ceramic plate during the heating of the heating element to maintain maximum heat transfer between the heated aluminum plate and the glass-ceramic aluminum plate, said metallic spring means being a strong sheet metal member with a planar top surface adapted to bear against the underside of the aluminum plate in the open central portion defined by the spiral heating element, said spring having a plurality of inclined support legs extending from beneath the top surface.

Claim 6

A surface heating unit as recited in claim 3 wherein the said reflector pan has a flattened support ledge underlying the peripheral edge of the aluminum plate, there being a thin layer of thermal insulating material compressed between the aluminum plate and the said ledge and between the aluminum plate and the top planar surface of the compression spring so as to restrict the conduction of heat to the reflector pan.

Claim 7

A smooth surface cooktop comprising a thin top plate of glass-ceramic material of relatively large area, a concentrated heated area of the glass-ceramic plate defined by an aluminum plate in contact with the underside of the glass-ceramic plate, a metal sheathed heating element fixed to the underside of the aluminum plate, a large metal plate underlying the glass-ceramic plate, the area of the metal plate surrounding the aluminum plate being in supporting engagement with the glass-ceramic plate, a narrow area of the metal plate underlying the peripheral edge of the aluminum plate and being in supporting engagement with said aluminum plate, the area of the metal plate underlying the central area of the aluminum plate being drawn into a reflector pan, and a metallic spring seated in the reflector pan and compressed against the underside of the aluminum plate to ensure good thermal coupling between the heated aluminum plate and the glass-ceramic plate.

Claim 8

A smooth surface cooktop comprising a thin top plate of glass-ceramic material of relatively large area, a concentrated heated area of the glass-ceramic plate defined by an aluminum plate in contact with the underside of the glass-ceramic plate, a metal sheathed heating element fixed to the underside of the aluminum plate, a large metal plate underlying the glass-ceramic plate, the area of the metal plate surrounding the aluminum plate being in supporting engagement with the glass-ceramic plate, a narrow area of the metal plate underlying the peripheral edge of the aluminum plate and being in supporting engagement with said aluminum plate, the area of the metal plate underlying the central area of the aluminum plate being drawn into a reflector pan, and a metallic spring seated in the reflector pan and compressed against the underside of the aluminum plate to ensure good thermal coupling between the heated aluminum plate and the glass-ceramic plate.

Claim 9

A smooth surface cooktop as recited in claim 5 wherein the outer portion of the said large metal plate surrounding the reflector pan portion is provided with a plurality of spaced reinforcing rib means to ensure a rigid support means for the glass-ceramic plate.

Claim 10

A smooth surface cooktop as recited in claim 6 wherein a thin layer of thermal insulating material is sandwiched between the aluminum plate and both the narrow area of the underlying metal plate and the metallic spring.

Claim 11

A smooth surface cooktop as recited in claim 7 with a high temperature adhesive bonding the glass-ceramic plate to the said metal plate in the area surrounding the aluminum plate.

Claim 12

A smooth surface heating unit comprising a flat plate of glass-ceramic material supported on an aluminum plate having a metal sheathed heating element attached thereto for furnishing heat to the glass-ceramic plate, the top surface of the aluminum plate having a high emissivity coating to improve the transfer of heat to the glass-ceramic plate, a deep drawn reflector pan underlying the aluminum plate, the reflector pan having a narrow shelf on which the aluminum plate is seated, a metal spring seated in the reflector pan and bearing against the underside of the aluminum plate to ensure good thermal coupling between the aluminum plate and the glass-ceramic plate at all times, the said glass-ceramic plate being of enlarged size to extend beyond the boundaries of the aluminum plate, the reflector pan also being of enlarged size with a generally planar area supporting the extended area of the glass-ceramic plate, an open-topped mounting box in which the surface heating unit is supported, and adhesive means joining the glass-ceramic plate to the reflector pan, and adjustable clamping means for sealing the peripheral edge of the heating unit to the mounting box.

Claim 13

A smooth surface heating unit comprising a flat plate of glass-ceramic material supported on an aluminum plate having a metal sheathed heating element attached thereto for furnishing heat to the glass-ceramic plate, the top surface of the aluminum plate having a high emissivity coating to improve the transfer of heat to the glass-ceramic plate, a deep drawn reflector pan underlying the aluminum plate, the reflector pan having a narrow shelf on which the aluminum plate is seated, a metal spring seated in the reflector pan and bearing against the underside of the aluminum plate to ensure good thermal coupling between the aluminum plate and the glass-ceramic plate at all times, the said glass-ceramic plate being of enlarged size to extend beyond the boundaries of the aluminum plate, the reflector pan also being of enlarged size with a generally planar area supporting the extended area of the glass-ceramic plate, an open-topped mounting box in which the surface heating unit is supported, and adhesive means joining the glass-ceramic plate to the reflector pan, and adjustable clamping means for sealing the peripheral edge of the heating unit to the mounting box.

Claim 14

A smooth surface electric cooktop comprising a large open-topped mounting box supporting a plurality of glass-ceramic plate heating units, where each heating unit includes a large flat plate of glass-ceramic material supported on a smaller thin metal heating plate of high heat conductivity having a metal sheathed heating element attached thereto for furnishing heat to the glass-ceramic plate, a large metal support plate underlying the large glass-ceramic plate, said metal support plate engaging the glass-ceramic plate in the area surrounding the heating plate, as well as engaging the peripheral edge of the heating plate, the main portion of the metal support plate beneath the heating plate being formed into a dished reflector pan, and reinforcing means cooperating with the heating plate to prevent warpage of the heating plate when it is subjected to high thermal stresses.

Claim 15

A smooth surface electric cooktop comprising a large open-topped mounting box supporting a plurality of glass-ceramic plate heating units, where each heating unit includes a large flat plate of glass-ceramic material supported on a smaller thin metal heating plate of high heat conductivity having a metal sheathed heating element attached thereto for furnishing heat to the glass-ceramic plate, a large metal support plate underlying the large glass-ceramic plate, said metal support plate engaging the glass-ceramic plate in the area surrounding the heating plate, as well as engaging the peripheral edge of the heating plate, the main portion of the metal support plate beneath the heating plate being formed into a dished reflector pan, and reinforcing means cooperating with the heating plate to prevent warpage of the heating plate when it is subjected to high thermal stresses.

Claim 16

A smooth surface electric cooktop as recited in claim 10 with the addition of a high temperature adhesive bonding the metal support plate to the glass-ceramic plate in the area surrounding the heating plate, said adhesive also serving as a shock absorbing means.