| 摘要 |
<p>Electrical resistance heating element comprising at least one heating conductor in the form of an element which is provided at opposite surfaces with an electrical contacting means and is made of a material having a positive temperature coefficient of electrical resistance (PTC element), and further comprising two substantially plane contact plates, the contact plates being held together with the PTC element interposed between them to form a single unit acting as a contact arrangement, and a sleeve of electrically insulating, heat conductive material having an inner space whose internal cross-section is adapted to the cross-section of the contact arrangement, the contact arrangement being inserted into the inner space in the sleeve under a pressure perpendicular to the plane of the contact plates. The sleeve consists of elastomeric material. With a view to achieving good and uniform heat dissipation the contact plates project a considerable distance beyond the PTC element, a spacer web portion of the sleeve being provided between them to form guide ducts into which the contact plates are inserted. These ducts may be formed to diverge in the direction of insertion of the contact arrangement. At the outer end of the sleeve, connecting leads are bonded to the ends of the contact plates and these are embedded in a holding element of insulating material. This element may be formed as a plug which closes and seals the sleeve when the contact arrangement is inserted; alternatively it may be cast into the outer end of the sleeve after insertion of the contact arrangement.</p> |
