Abstract: A gas fired furnace system (10) has a controller (14) controlling the supply of gas through a gas valve (12) and air for combustion by means of an induced air draft fan (28), ignition of the gas by means of ignitor (22), the delivery of heated air from a heat exchanger (20) by means of an air blower (34) in response to signals from a thermostat (42). A selected constant flow of air for combustion is provided by controlling the speed of the motor driving the induced motor fan (28) despite changes which may occur in back pressure. Induced draft fan motor parameters proportional to motor torque and motor speed are read on an ongoing basis and inputted to controller (14) which computes a desired voltage and compares that with referenced data stored in the controller memory and makes corrections to the speed of the induced draft fan motor to maintain the constant air flow.

Abstract: A gas fired furnace system (10) has a controller (14) controlling the supply of gas through a gas valve (12) and air for combustion by means of an induced air draft fan (28), ignition of the gas by means of ignitor (22), the delivery of heated air from a heat exchanger (20) by means of an air blower (34) in response to signals from a thermostat (42). A selected constant flow of air for combustion is provided by controlling the speed of the motor driving the induced motor fan (28) despite changes which may occur in back pressure. Induced draft fan motor parameters proportional to motor torque and motor speed are read on an ongoing basis and inputted to controller (14) which computes a desired voltage and compares that with referenced data stored in the controller memory and makes corrections to the speed of the induced draft fan motor to maintain the constant air flow.

Abstract: A gas fired furnace system (10) has a controller (14) controlling the supply of gas through a gas valve (12) and air for combustion by means of an induced air draft fan (28), ignition of the gas by means of ignitor (22), the delivery of heated air from a heat exchanger (20) by means of an air blower (34) in response to signals from a thermostat (42). A selected constant flow of air for combustion is provided by controlling the speed of the motor driving the induced motor fan (28) despite changes which may occur in back pressure. Induced draft fan motor parameters proportional to motor torque and motor speed are read on an ongoing basis and inputted to controller (14) which computes a desired voltage and compares that with referenced data stored in the controller memory and makes corrections to the speed of the induced draft fan motor to maintain the constant air flow.

Abstract: An electric switch is shown which is responsive separately to two different conditions, i.e. temperature and pressure. The switch includes a temperature sensing disc and a pressure sensing disc both coupled through several alternate motion transfer arrangements to the movable electrical contact of the switch. Several structures are shown for mounting a switch on a surface so that the pressure sensing disc is exposed to fluid pressure and the temperature sensing disc is thermally coupled to the surface.

Abstract: Differentially connected capacitive sensors are mechanically coupled with the flexible capacitor plate of one sensor coupled to the source of pressure to be measured, the flexible capacitor plate of the other sensor coupled to ambient pressure. In a second embodiment, inaccuracies due to forces on the flexible plate are minimized by providing a housing with a tapered inner wall, an O-ring and a support to apply a radial load to the sensor due to clamping action from the tapered housing against the O-ring to provide a seal for the pressure sensing chamber. In a further embodiment, the cost of fabrication of the pressure transducer is minimized by providing the housing as a one piece cup. The electronics are mounted on the exterior surface of the low pressure side of the ceramic capacitor pressure sensing element and sealed in thereat by potting with an epoxy.

Abstract: A housing has a switch chamber in which an electric switch is placed and a recess in which is received a snap acting, thermally responsive disc which actuates and deactuates the switch upon snapping from one configuration to another. A thermal biasing assembly used to modify the operating temperature of the disc has a pair of cylindrical film type resistors electrically connected in parallel circuit relation and physically connected to a pair of rivets. Resistors of a rating chosen for a particular application are dropped into the recess with the leads of the resistors received in bores provided in the housing. A rivet is then inserted into each bore making good electrical connection with the leads without welding by deforming them a selected amount. The rivets are attached to suitable terminals and the disc is then placed over the thermal biasing assembly to provide a multiple temperature operating thermostat.

Abstract: A housing has a switch chamber in which an electric switch is placed and a recess in which is received a snap acting, thermally responsive disc which actuates and deactuates the switch upon snapping from one configuration to another. A drop in thermal biasing assembly used to modify the operating temperature of the disc has a pair of cylindrical film type resistors electrically connected in parallel circuit relation and physically connected to a pair of connectors. An assembly having resistors of a rating chosen for a particular application is dropped into the recess before the disc is assembled, the connectors sliding into matching bores formed in the housing. The connectors are attached to suitable teminals and the disc is then placed over the thermal biasing assembly to provide a multiple temperature operating thermostat.

Abstract: A housing has a switch chamber in which an electric switch is placed and a recess in which is received a snap acting, thermally responsive disc which actuates and deactuates the switch upon snapping from one configuration to another. A drop in thermal biasing assembly used to modify the operating temperature of the disc has a pair of cylindrical film type resistors electrically connected in parallel circuit relation and physically connected to a pair of connectors. An assembly having resistors of a rating chosen for a particular application is dropped into the recess before the disc is assembled, the connectors sliding into matching bores formed in the housing. The connectors are attached to suitable terminals and the disc is then placed over the thermal biasing assembly to provide a multiple temperature operating thermostat.

Abstract: A sealed pressure-responsive switch is manually resettable and trip-free. The switch has a separate snap-acting, bistable, dished metal disc or disc element disposed between a sealed snap-acting pressure-responsive diaphragm and a spring-biased switch arm. The disc moves to an inverted dished configuration with snap action to move the switch arm to a trip position against the arm bias when the diaphragm moves in response to application of a selected fluid pressure. The disc remains in its inverted shape to releasably hold the arm in tripped position until the switch is manually reset even when the diaphragm returns to its original position after removal of the selected fluid pressure from the diaphragm.

Abstract: A control for modulating the duty cycle of diesel engine glow plugs has two heat sensitive, normally closed switches each thermally coupled to a respective positive temperature coefficient (PTC) of resistivity heater in turn thermally coupled to a common heat sink. The heat sensitive switches are serially connected to each other, to an ignition switch and to a glow plug relay. The PTC heaters are connected to a point between the heat sensitive switches and the relay and to ground. A third PTC heater is disposed on the heat sink intermediate the first and second heaters and thermally coupled to the heat sink. The third heater is connected to an alternator and serves to cut off power to the glow plugs after a selected after glow stage. The two heat sensitive switches can be selected to open at approximately the same temperature for a random operating mode or at slightly different temperatures for a sequential operating mode.

Abstract: A thermally actuated valve assembly comprising a housing having a passage extending therethrough with the passage having an inlet, an outlet and a valve seat therebetween. A thermostatic dish-shaped bimetallic disk constituting a valve member is positioned in the passage and is abruptly movable over center from a first curvature position in which the outer periphery of the disk is in engagement with the valve seat thereby to block communication through the passage and a second curvature position in which the disk is clear of the valve seat to permit the flow of fluid therepast. The disk is movable from its first to its second curvature position upon being subjected to a first temperature and is returnable from its second to its first curvature position upon being subjected to a second temperature. A spring member biases the disk toward the valve seat and holds the disk in sealing engagement therewith when the disk is in its first curvature position.

Abstract: A valve assembly with a water dispersing and spreading system preferrable for use in drip-type beverage maker comprising a housing having a passage extending therethrough with the passage having an inlet, an outlet, and a valve seat therebetween. A thermostatic dish-shaped snap-acting bimetallic disk constitutes the valve member and is positioned in the passage in engagement with the valve seat thereby to block communication through the passage while in the first curvature position and while in the second curvature position to move clear of the valve seat to permit the flow of fluid therepast. The disk is movable from the first curvature position to the second and back again upon changes in temperature of the disk. A spring member biases the disk toward the valve seat in sealing engagement when the disk is in its first curvature position.

Abstract: A self-regulating heater comprising a housing having a chamber therein and a heating element in the chamber. The heating element is a self-heating, positive temperature coefficient (PTC) resistor having low initial resistance which increases abruptly as its temperature rises above a given level. It has first and second substantially parallel surfaces spaced from one another, these surfaces each having a layer of electrically conductive material applied thereto for forming an ohmic contact surface. The heater further comprises a heat sink plate of thermally and electrically conductive material, the plate being positioned within the housing chamber so that one face of the plate is in heat-transfer relation with a first inside surface of the housing and so that the other side of the plate is in electrical contact and in heat transfer relationship with the first surface of the element.