Abstract: A heating system and air conditioning system incorporating a duty cycling control switch are disclosed. The duty cycling control switch for either the furnace or air conditioning system is mounted within the supply side duct of the system, i.e., the hot air duct for a furnace or cold air duct for an air conditioner. The duty cycling control is a bi-metal switch totally enclosed within a case having a metal base whereby the heat from the air in the duct contacts the metal base which is transferred to a bi-metallic element which in turn opens or closes a switch. This makes the switch particularly responsive to gradual changes in the temperature of the output air but prevents the duty cycling switch from responding to rapid fluctuations of air temperature within the duct.
Abstract: A temperature sensor which is flush mounted on a wall of a room in which the temperature is sensed. A mounting plate secured to the wall has a cavity in its face which receives an aluminum sensor plate and an insulating block which thermally insulates the sensor plate from the mounting plate. A temperature sensing integrated circuit contacts the back side of the sensor plate and has electrical leads which extend to the back side of a printed circuit board mounted in a pocket on the back side of the mounting plate. The integrated circuit acts as a current source having its output signal enhanced by active solid state circuit components mounted on the back side of the circuit board where their heat is dissipated by conduction through the mounting plate and wall and by convection and radiation into the wall cavity to avoid affecting the sensor plate. The circuitry allows active factory calibration and eliminates adverse effects on the signal caused by background environmental noise.
Abstract: An electric heating appliance such as a coffeemaker, has a metallic base with an upper exposed surface and an electric heater on its lower side for heating the surface by conduction. A thermostat comprising a plastic-walled packaged unit with an opening through which an internal bimetal sensor is exposed is provided for controlling the heater and is mounted in a depressed niche formed in the surface of the heater. A detachable U-shaped metallic cover covers the opening and includes a heat-conducting projection extending through the opening very closely adjacent the sensor. The thermostat is positioned so that the cover faces and abuts the surface of the niche and a flexible clamp secures the thermostat in the niche and biases the projection and sensor closely together for fast thermostat response. The base may be an aluminum casting with the heater comprising a cast-in circular sheathed electric heating element.
Abstract: A thermal switch having relatively high gain for stabilizing the temperature of a heat source or a heat sink, especially useful in vacuum applications. A strip of heat conducting material is disposed to conduct heat from one heat station to another heat station. The contact made between the strip of heat conducting material and a heat station is subjected to a variable contact pressure. This contact pressure varies in response to changes in the temperature of a quantity of a heat expandable fluid material confined to a chamber thermally connected to whichever heat station is to be subjected to temperature control. This fluid preferably has a high bulk modulus. The fluid actuates a piston disposed to bear against the strip of heat conducting material whereby the pressure at the interface between the strip and the contacted heat station is varied. The heat conducting materials in contact with each other at this interface preferably have a low yield strength.
Abstract: The device includes a thermostat which is potted or secured by epoxy in a recess in the closed end of a generally cup-shaped, dielectric housing. A generally disc-shaped, aluminum alloy casting is secured coaxially against an opening formed in the bottom of the housing, and against a PTC resistor which is positioned in the opening between the casting and the thermostat, and in electrical contact with the latter. A bimetallic coil is mounted in the open end of the housing with its inner end staked to an integral post on the Al casting, and with its free end mounted to unwind or rotate angularly in the housing with changes in ambient temperature. The Al casting functions as a heat sink which can be trimmed, before being secured in the housing, to calibrate the bimetel coil.