Abstract: The present invention provides an improved means of connecting the end of a bimetal blade, from which the bimetal flexes, to a planar member of a thermostatic switch. The bimetal blade, in response to temperature changes of the ambient, flexes to alternately establish circuit closed and open conditions of the switch. In a preferred embodiment, the planar member is a contact strip that overlies the basewall of a non-conducting case. The attachment provided by the present invention increases the cyclical life expectancy of the bimetal blade by locating a preloaded weld button against the one attached end of the bimetal blade in a press fit wherein a pressure, exerted by the weld button, prevents movement of the bimetal blade. A weld penetrates the planar member, the bimetal blade and the weld button to prevent relaxation of the pressure. In the connection of the present invention, the blade is held in place essentially by the pressure exerted by the weld button rather than by the weld itself.

Abstract: The present invention provides a method of forming a thermostatic switch having a calibrated operating temperature range that is defined by a calibrated actuation temperature and a calibrated reset temperature. In accordance with this method a snap action thermostatic switch is provided having a bimetal blade with a snap acting depression. The blade is formed to have a range of actuation temperatures above the desired actuation temperature and a range of reset temperatures below the desired reset temperature. The actuation temperature is calibrated in a heated temperature environment that has an initial temperature that is equal to the desired actuation temperature by a fulcrum-like calibration projection. The reset temperature is then calibrated in the heated temperature environment, after the temperature has been lowered to equal the desired reset temperature.

Abstract: A creepless, snap action thermostat is formed employing two movable contacts. One of the contacts is mounted to a bimetallic arm which moves as the temperature of the environment in which the thermostat is located increases. The second movable contact is mounted on a spring arm, the spring arm following the motion of the bimetallic arm upon increased heating, so as to maintain firm mating of the two contacts until the snap over point of the bimetal is reached. After snap over, the contact on the spring arm is prevented from following the contact on the bimetallic arm because of a physical stop formed in the thermostat casing.