Adhesive system for attaching PTC heater to a wax motor

DETAILED DESCRIPTION The present invention provides an adhesive system in which multiple distinct zones of different types of adhesives are used to assemble PTC resistor and wax motor together.
These distinct zones allow the selection of individual adhesives optimized for different properties.
Further, by placing the conductive adhesive within zones of non-conductive adhesive, the non-conductive adhesive can be used to corral the conductive adhesive limiting its potential for creating short circuit paths.
Specifically, the present system provides a thermal actuator of a type having a wax motor element with a face attached to a PTC resistor where a first adhesive material attaching the PTC resistor to the face of the wax motor is placed in a first zone on the face and a second adhesive material attaching the PTC resistor to the face of the wax motor is placed in a second zone on the face.
The first and second adhesive materials have substantially different properties of electrical conduction.
The first and second adhesives may also have different thermal conduction properties.
Thus, it is one object of at least one embodiment of the invention to optimize properties of adhesion and thermal conductivity independently of electrical conductivity through the use of multiple adhesives with independently adjustable zones.
The first adhesive may have substantially greater electrical conductivity than the second adhesive and the second adhesive may have stronger adhesive properties than the first adhesive.
Thus, it is another object of at least one embodiment of the invention to provide improved adhesion over that which can be obtained by suitable electrically conductive adhesives.
The first adhesive may have substantially greater electrical conductivity than the second adhesive and the first zone may be substantially smaller an area than the second zone.
Thus, it is another object of at least one embodiment of the invention to limit the amount of conductive adhesive used to eliminate problems of inadvertent short circuits