Abstract: A thermally activated electrical interrupt device incorporates a thermally activated portion engaging with an electrical interrupt portion. The thermally activated material expands when heated, causing an interrupt control rod to open an electrical contact. When the interrupt device is placed into an interrupt state, a reset mechanism maintains the interrupt control rod in the interrupt state until specifically reset. An actuating shaft is in operational communication with at least one electrical contact. The actuating shaft is maintained in a thermal monitoring position until an interrupt control rod is moved via a thermally expanding material and engages with the actuating shaft, releasing it from the thermal monitoring position. The actuating shaft is projected via a biasing member to cause a change in state of the electrical contact. The actuating shaft remains in the interrupt state until the user resets the switch.

Abstract: A mechanical displacement amplifier is disclosed in which a displacement amplifying spring member essentially in the shape of a shallow V is positioned between a reference point structure and a displacement member so as to buckle in response to movement of the displacement member towards the reference point structure. A dimple is provided adjacent the buckling point of the spring member to prevent it from straightening entirely. A thermostat embodying the mechanical displacement amplifier is also disclosed, in which a push rod between a microswitch and the buckling point of the spring member actuates the microswitch. A temperature adjustment dial positions the reference point structure, and a temperature sensing unit is the displacement member.

Abstract: A two-circuit automatic hotplate has a switch, which can be controlled both by a bimetallic strip of a power control device and by an expansion member of a hydraulic temperature sensor. The control heating system of the bimetallic strip is in series with a cooking heating system of the hotplate.The electric power levels of the cooking heating systems are preferably selected in such a way that, wherever possible, a current of the same level flows through the control heating system for the bimetallic strip, so that the same bimetallic strip can always be used.

Abstract: An electric hot plate has an overheating safety switch having a steatite housing which is inserted into the lower sheet cover plate of the hot plate and is supported with two feet on the lower side of the heating elements of the hot plate. A bimetallic member is positioned parallel between these feet which acts on a snap switch positioned in the steatite housing via a transmission rod. The transmission rod is continuously pressed against the snap switch by a plate spring and a guide on the snap switch. As a result of this, it is fixed precisely in its position. The overheating safety switch simultaneously forms the lead-through passages for the electric hot plate connections.

Abstract: Movement of the diaphragm pad occasioned by change in pressure within the diaphragm in response to a change in sensed temperature causes the bowed actuating spring to increase or decrease the degree of flexure to actuate the switch. In order to accommodate the pressure variations induced by a wide range of ambient temperature conditions the diaphragm is preloaded by a second bowed spring. A cam mechanism can be provided to vary the flexure of the preloading spring to thereby adjust the temperature at which the switch will be actuated.

Abstract: A temperature limiter used as part of, or otherwise in combination with, an electric cooking plate. An improved switching hysteresis is enabled by a unique construction in which a laterally open recess is formed in a one-piece housing to receive a snap switch, the counter-contact of which is fixidly secured in slot structure adjacent said recess. A transmission rod is arranged within an expansion sleeve and is positioned to be spring biased through engagement with the spring of a snap switch.

Abstract: A thermostat useful for an appliance, which uses a snap action stressed-leaf spring having two stable stressed configurations for the making and breaking of a circuit. Stressing of the spring is provided by differential movement of parts of a heat probe.

Abstract: A differential expansion rod and tube thermostat wherein the material of the inner rod has a much lower coefficient of thermal expansion than does the material of the outer tube. The thermostat is adapted to be mounted through an opening in the wall of an oven cooking cavity. A certain amount of the tube remains outside the oven cooking cavity. The inner rod is adapted to lie within the oven cooking cavity. Joined to the inner rod is an extension strap of a material having a high linear coefficient of thermal expansion substantially the same as that of the outer tube. The longitudinal motion created by the difference in the rates of expansion between the outer tube and the combined inner rod and extension strap is transferred by a hinged amplifier lever to a switch mechanism which is calibrated to operate at a predetermined oven temperature.

Abstract: A thermal fixing device for a xerographic reproducing apparatus includes a thin planar resistance heating element having a low thermal mass and a high coefficient of thermal expansion. The heating element is supported in such manner that one end thereof is free to move linearly under thermal expansion to activate a heater displacement detector comprising a pivotally mounted lever arm having a right angle configuration. One end of the lever arm is received in an opening in the heating element and the other end form a contact of a normally open switch which is adapted to be closed by pivoting of the arm due to expansion of the heating element. Closure of the switch activates a power controller to interrupt the power supply to the heating element.