Abstract: A self-cleaning over door latching mechanism is provided with a locking arrangement responsive to the oven cavity temperature, which includes a locking pin moved by a snap action bimetal member mounted in thermal communication with an oven cavity wall. The bimetal member moves the locking pin to a locking position when the temperature sensed by the bimetal rises above the locking temperature. In its locked position the locking pin prevents the opening of the latch until the temperature in the oven cavity falls below the locking temperature. In its locked position the locking pin also actuates a lock switch electrically connected in parallel with a thermal limit switch. The thermal limit switch provides over temperature protection for the cavity when operating in the normal cooking modes. When actuated, the lock switch shunts the limit switch thereby enabling the temperature in the cavity to rise to the self-clean range.

Abstract: A cooking appliance equipped for indoor grilling includes an integrally formed, sheet metal reflector pan interposed between the grill member and the drip pan. The reflector pan has a bottom wall which extends beneath the heating element and four generally upwardly extending side walls to shield the area laterally adjacent the grill area from the radiant energy of the heating element. The reflector pan is configured between its corners to define an air gap between the reflector pan and the adjacent cooktop which provides an air flow path between the area above the cooktop and the area between the drip pan and the reflector pan. When the heating element is energized cooling air is drawn by convection from above the cooktop downwardly through the air gap into the area between the drip pan and the reflector pan and upwardly through narrow slots in the bottom of the reflector pan.

Abstract: A capacitive touch pad assembly which provides a touch control panel for an appliance with white touch pad appearance. A thin dielectric substrate has an outer touch electrode of a relatively dark-colored conductive material deposited on its outer surface and a pair of spatially separated inner electrodes formed on the inner surface of the dielectric layer for connecting to the control circuitry. To achieve a light-colored appearance for the touch pads, a layer of relatively light-colored non-conductive decorative material is applied to the outer surface overlaying the electrode to hide its dark color except for a small exposed area of the electrode which defines a symbol relating to the function of the pad. The exposed area may be covered by a second layer of dark conductive material or left exposed. The symbol enables direct human body member contact with the outer electrode.

Abstract: A microwave heating system uses a magnetron powered by a full wave full bridge inverter. The magnetron has its power output stabilized against variations which might be caused by fluctuations in the AC input line. The inverter powers the magnetron by way of a power transformer having a primary and a secondary. The current is sensed in the primary in order to change the switching frequency of the inverter. As the current in the primary will depend upon fluctuations in the AC input line voltage, sensing of the current in the primary may be used to sense variations in the voltage of the AC input line. Alternately, current in the secondary of the power transformer may be sensed and used to detect variations in the AC input line voltage. In either case, the sensed variations in AC input line voltage are used to change the inverter frequency.

Abstract: An arrangement for providing power to a cooking magnetron uses a ful wave bridge inverter circuit connected to a power transformer. The filament of the magnetron is energized by a secondary winding of the power transformer. The inverter controls the microwave output of the magnetron by duty cycle control. In order to stabilize filament power against variations due to changes in the inverter duty cycle, a saturable reactor is connected in series with the filament. The reactor has a control winding which changes the impedance of the reactor in order to compensate for variations in the power supplied by the power transformer. The control winding of the reactor may be supplied with a voltage dependent upon the magnetron current. Since the magnetron current depends on the duty cycle of the inverter, this voltage may be used to make the impedance of the reactor dependent upon the duty cycle.

Abstract: A microwave oven uses a full wave full bridge inverter for supplying energy to a cooking magnetron by way of a power transformer. The inverter is controlled by a microprocessor which acts upon a control circuit having an oscillator. The control circuit provides gating pulses which are used to switch on FET switches in the inverter. The microprocessor stops and starts the gating pulses. The microprocessor may adjust the power of magnetron by turning the control circuit on and off for variable time intervals. Alternately, the microprocessor may control the power of the magnetron by changing the switching frequency of the inverter. The microprocessor is used in a filament standby mode to monitor the current in the magnetron's filament. In the filament standby mode, the inverter is operated at a lower than normal voltage such that the magnetron is not generating microwave power, but its filament is receiving sufficient current to warm it up, the current flowing through a filament winding of a power transformer.

Abstract: An improved power control system for a household cooking appliance of the type having a glass ceramic cooking surface and at least one radiant heating unit disposed beneath the cooking surface operable at a plurality of user selectable power settings. At least one of the power settings has associated with it predetermined maximum and minimum reference temperatures defining a temperature band representative of the steady state temperature range for the glass ceramic support surface proximate the heating unit when heating normal loads at that power setting.

Abstract: A temperature sensor assembly for an automatic solid disk surface unit includes a temperature sensor enclosed in a metallic hermetically sealed generally cylindrical housing. Upper and lower centrally apertured annular disks formed of a porcelain ceramic material thermally isolate the sensor housing from the surrounding surface unit. A protective metallic skirt conforming to the outer contour of the insulating disks holds the assembly together. A layer of glaze material covers the exposed upper surface of the upper disk in the gap between the skirt and the housing to prevent the absorption of food soils.

Abstract: A method and apparatus for testing the operability of an overload protection device for an induction motor, rapidly and without the need to mechanically load the motor output shaft. A rectifier circuit converts a standard AC input power signal to an unfiltered full wave rectified output power signal which is applied to the input terminals of the motor under test to rapidly heat the overload device to its trip temperature. The output power signal is periodically interrupted for brief periods of sufficient duration to extinguish any arcing occasioned by the opening of the overload device contacts. The period between successive interrupt periods is selected to be short enough to extinguish any such arcing before the contacts are damaged. If the contacts of the protection device fail to open within a predetermined time period, a signal is generated to indicate that the overload device has failed to operate properly.

Abstract: An improved temperature sensor failure detection arrangement for a temperature controlled heating device of the type having a heater, an electronic controller for controlling the power level applied to the heater, and a temperature sensor. The controller includes an internal heater energy counter, which is incremented and decremented at rates determined as a function of the power level applied to the heater such that the count of the heater energy counter approximately tracks the temperature of the heater. The controller periodically compares temperature information from the temperature sensor with the count of the heater energy counter to check for abnormal operating condition of the temperature sensor.

Abstract: A power control switching arrangement for controlling energization of a load in response to an external controller, in which a first semiconductor switch is connected in parallel with the series combination of a first normally open thermally actuated switch and a second normally closed thermally actuated switch, to couple the power signal to the load. A first heater for the first thermal switch is connected in parallel with the load. A second heater for the second thermal switch is connected in series with a second semiconductor switch, across the power supply. The second semiconductor switch, when switched into conduction by the controller, enables energization of the second heater. To energize the load, the controller switches the first semiconductor switch into conduction enabling energization of the load and the first heater. Energization of the first heater closes the first thermally actuated switch, thereby shunting the first semiconductor switch.

Abstract: An improved electric cooking appliance with a plurality of heating units arranged in two groups, a first group adapted for energization by a first AC power signal and a second group adapted for energization by a second AC power signal, 180.degree. out of phase relative to the first power signal. The heating units of the first and second groups are each connected to a common neutral power line.

Abstract: A solid disk surface unit mounted in a glass or ceramic support surface, comprising a plate member of cast material with one or more resistive heating elements mounted to the underside thereof and a thermally conductive cover member enclosing the underside of the plate member with its peripheral edge in close thermal contact with the plate member near its periphery, is provided with a thermally responsive switching device thermally coupled to the cover member and adapted to respond to the surface temperature of the cover member at a point relatively remote from its peripheral edge. The switching device is operative to remove power from the resistive heating elements of the surface unit when the sensed cover member temperature exceeds a predetermined threshold temperature, thereby protecting the glass support surface from damage due to thermal stresses resulting from hot spots occurring near the periphery of the surface of the plate member.

Abstract: An improved power control system for a glas-ceramic cooktop appliance of the type having at least one radiant heating unit disposed beneath the glass-ceramic cooking surface, and a user actuable input keyboard to enable the user to select one of a plurality of power settings for the heating unit. The control system monitors the glass-ceramic temperature and the rate of change of the glass-ceramic temperature to detect abnormal thermal load conditions on the glass-ceramic cooking surface. Upon detection of an abnormal load condition, the power level applied to the heating unit is lowered as a function of the sensed glass-ceramic temperature, the temperature rate of change, and the user selected power setting, to limit the temperature of the glass-ceramic cooking surface so as to avoid damage by excessive temperatures resulting from the abnormal thermal load conditions on the cooking surface.

Abstract: A power control system for operating a heating element in a cooking appliance in response to the selection of one of a plurality of user selectable power settings. Approximate heating element temperature information is provided by a heater energy counter. Each power setting has associated with it a corresponding steady state power level and a corresponding predetermined steady state energy count. The steady state energy count is approximately proportional to the steady state operating temperature of the heating element when operated at its corresponding steady state power level. The energy counter is selectively incremented and decremented to approximately track the heating element temperature when the count is respectively less than or greater than the steady state count for the applied power level. At least certain ones of the power settings have corresponding minimum threshold counts less than the steady state counts and maximum threshold counts greater than the steady state counts.

Abstract: A refrigerator food storage compartment having a shelf assembly, including a pair of vertically extending laterally spaced rail members. A shelf is supported on a pair of horizontally extending arm members which are positioned on the rail members. Carried on the shelf assembly is a secondary food storage arrangement supporting a plurality of containers. The arm members include confronting grooves arranged below the shelf. Slidably arranged in the grooves is a container supporting frame which includes pairs of confronting flanges supporting the containers. Forward travel of the container supporting frame relative to the shelf assembly provides access to the containers. The front portion of the frame includes a front opening through which the containers may be removed while the container supporting frame remains positoned below the shelf.

Abstract: A method for testing motors having separate run and start windings to verify correct motor size and to detect miswiring of the motor windings comprises the steps of measuring the start winding resistance, measuring the run winding resistance, calculating a ratio of the start winding and run winding resistances and comparing the calculated ratio to a predetermined range representative of the desired motor size when correctly wired and rejecting the motor if the calculated ratio does not come within this predetermined range, and apparatus for same.

Abstract: Disclosed are refrigeration system control systems and methods for compressor motor protection and defrost control. The disclosed systems and methods are generic in the sense that they are self-calibrating and so may be employed in a variety of different air conditioner or heat pump models of different sizes and capacities, without being specifically tailored for a particular model. The disclosed systems and methods sense loading on the compressor and evaporator fan motors, preferably by sensing the voltage across the capacitor-run winding of an AC induction motor and normalizing with respect to line voltage. The self-calibrating capability is implemented by taking advantage of the changing loads as a function of time on both the compressor and fan motors during both normal and abnormal operation of a refrigeration system. In overview, a reference value of motor loading is established for each motor at certain times during an ON cycle.