Kanthal Ab

Bulten-Kanthal Ab

Bengt Hjortsberg

Tommy Fredriksson

The invention is for a flat electrical heating resistance element, so called foil elements. Elements according to the invention can be used for many purposes, however, it is specially intended for use as heating elements for water beds. The object of the invention is to minimize the electromagnetic fields caused by the elements. The influence of such magnetic fields on humans is on the whole unknown why there is a common desire that the strength of these magnetic fields shall be as low as possible in order to minimize effects, if any. Heating elements according to the invention have electrical resistance wire or band placed in loops on a plastic foil surface, whereby the loops have four with each other parallel conductors, electrically connected so that in any given moment the direction of the current in the two outer conductors are in the same direction and in the two inner conductors in the same direction opposite to the outer conductors.

Flat electrical resistance heating element

A resilient snap-on electric heating jacket for heating tubular objects includes a thin sheet of flexible plastic material constituting a radially internal curved surface adapted to engage the surface of the object. A pattern of spaced electrically conductive loops are formed on the radially external surface of the sheet to define an electric heating element. A thick resilient support member of polymeric material coextensive with and overlying the external surface of the plastic sheet and the foil loops is directly secured to the external surface portions of the foil loops and the plastic sheet by an autogenous bond to form a unitary structure generally C-shaped in cross section and capable of being snapped onto a tubular object the outer diameter of which corresponds approximately to the inner diameter of the profile of the unitary structure. The profile of the support member encloses an angle between 180.degree. and 270.degree. and preferably between 200.degree. and 250.degree..

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Hallstahammar, Sweden

Bengt Hjortsberg