초록 ▼

An adaptive defrost control for a refrigerator is shown in which a single linear power supply (12) and microprocessor (U1) is used for both the adaptive defrost and cold control functions. According to a feature of the invention, a zero current crossing point switching scheme may be used to improve

An adaptive defrost control for a refrigerator is shown in which a single linear power supply (12) and microprocessor (U1) is used for both the adaptive defrost and cold control functions. According to a feature of the invention, a zero current crossing point switching scheme may be used to improve relay cycle life. According to another feature, a calibration procedure based on line frequency may be used to obtain multiples of a selected unit of time for any accumulated compressor run time and defrost heater energization times. According to another feature a sample and hold technique may be used to distinguish between noise and valid signals. In a modified embodiment, a toroid (40) has a primary connected to a common line leading to the compressor motor (24) and defrost heater (26) to provide a signal (ST) which, when taken with the state of relay contacts in respective lines energizing the compressor motor and defrost heater, as determined by the microprocessor, results in monitoring the compressor and defrost heater energization time. In another embodiment, a motor start control incorporating a PTC element (28) is combined with the adaptive defrost control. A double pole, single throw relay (K4) initiates both the compressor motor starting and refrigerator heater functions and open circuits the PTC element after starting has been completed in order to conserve power. In a modified embodiment the latter relay (K4) is used to start the compressor motor without the PTC element (28).

대표청구항 ▼

[ What is claimed:] [1.] An adaptive defrost system for refrigeration apparatus having a compressor motor and a defrost heater comprising a microprocessor and a first set of relay contacts in a first line connected to line voltage and being serially connected to the compressor motor and being movabl

[ What is claimed:] [1.] An adaptive defrost system for refrigeration apparatus having a compressor motor and a defrost heater comprising a microprocessor and a first set of relay contacts in a first line connected to line voltage and being serially connected to the compressor motor and being movable between first and second positions and a second set of relay contacts in a second line connected to line voltage and being serially connected to the defrost heater and being movable between first and second positions, coil means coupled to the microprocessor for actuating the first and second sets of relay contacts, a power supply for supplying a first low level of power for the microprocessor and a second high level of power for actuating the first and second set of relay contacts, feedback signal means connected to the first and second lines and to the microprocessor so that the microprocessor can monitor the energization of the compressor motor and the defrost heater, means to vary the accumulated operating time of the compressor motor based on the feedback signal, the feedback signal means including a common line connected between line voltage and the respective first and second lines, a toroid having a primary connected to the common line and a secondary connected to the microprocessor.