Electric heating – Heating devices – With heater-unit housing – casing – or support means
Patent
1997-03-07
1999-07-27
Walberg, Teresa
Electric heating
Heating devices
With heater-unit housing, casing, or support means
219217, H05B 334, H05B 100
Patent
active
059285486
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The subject invention concerns an electric heater designed to heat foam-moulded cushions, for instance in vehicle seats or mattresses.
BACKGROUND OF THE INVENTION
Electrically heated vehicle seats have been known since many years. The heating effect is generated by electric current which is supplied through a conductor having a suitable resistivity that ensures the desired degree of heat in the conductor. The resistance wire is positioned be- tween various layers of a textile material or a plastics material, known as carriers, forming a sheet-like heating element. Several such sheet layers are then to be glued together, sandwiching between them the heating wire proper. This is a comparitively expensive process. The finished heating element is then glued to the seat cushion, the latter usually being of foam-moulded construction. The seat cover is then placed on top. Usually, lashing trech are used for tightening the seat cover. This means that at least one such trench is formed in the foam-moulded cushion and the seat cover material is pulled down into the trench. When a sheet is used for the seat cushion this sheet is often also pulled down into the lashing trench, allowing the cover to be pulled down over the sheet. A condition therefor is that the lashing trench is essentially straight. In case the lashing trench is curved and/or several such lashing trenches are used the heater usually is in the form of several separately heated sheets. Obviously, this increases the costs considerably. When the vehicle is exposed to loads considerable shape changes occur in the foam-moulded cushion and usually the lashing trench is compressed laterally. In time this may lead to rupture of the electrical conductor with a result that the heater stops functioning. In case of heaters that are placed in the seat back the problems are similar, although seat backs are exposed to less load. Also in the case of cushions intended for furniture and bed mattresses there might be a need for electric heaters. The problems in connection with these applications are similar in several respects.
THE PURPOSE OF THE INVENTION
The purpose of the subject invention is to considerably reduce the above outlined problems by creating an electric heater intended to be embedded into foam-moulded cushions or into a part component of the cushion or the mattress during the casting operation.
SUMMARY OF THE INVENTION
The above purpose is achieved by the electric heater in accordance with the invention, exhibiting the characteristics appearing from the appended claims.
The electric heater in accordance with the invention thus essentially is characterised by the fact that it consists of an electric conductor, e.g. an insulated or non-insulated metal wire which is configured into the shape of one or several bands of closely juxtaposed bights each one of which comprises a loop portion and an open portion facing away from the associated loop, substantially all open portions being interconnected by means of local interconnection means, e.g. by means of glue, plastic welds or seems, whereby one or several bands of coherent patterns are formed, said patents intended to be positioned in a mould for casting of cushions or parts of cushions such that the heater to an essential extent becomes anchored in the cushion, or a part component of said cushion, in the very casting operation. Consequently, the electric heater in accordance with the invention comprises no carrier in the shape of a sheet but consists of one or several bands of interconnected patterns of the conductor. This means that these patterns have a very open or airy configuration facilitating their embedment in a foam-moulded cushion. Attempts to embed traditional heating elements together with carrier sheets during the casting operations have failed on account of the closed configuration of such elements, which have made them prone to be pressed upwards towards the surface during the casting. Usually the greatest advantages are achieved when the heater in accordance with the
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Paik Sam
Tocksfors Verkstads AB
Walberg Teresa
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