Control system for and method of controlling a cooking appliance

Abstract

A cooking appliance, such as a deep fat fryer, includes programmable control system which monitors the operation of the cooking appliance and enables appropriate actions at proper times. The system includes a microcomputer which implements various timing and control functions. Control switches select operational states of the appliance. A diode matrix allows selection of input data. A multiplex circuit interconnects input signals to the microcomputer, a monitor circuit turns off the appliance if multiplexing stops. A temperature control circuit generates a signal responsive to the cooking fluid temperature and compares it with various reference signals under control of the microcomputer. A cooking control circuit generates a voltage proportional to the cooking fluid temperature, modifies it according to the desired doneness of the food being cooked, and converts it to a current which charges the capacitor in an oscillator. The oscillator provides a series of pulses which vary in frequency as the temperature of the fluid varies. These pulses are multiplexed to the microcomputer. Output circuits connect the microcomputer to various contactors controlling operation of the appliance and to indicators, such as lights and a buzzer. The control system provides a low energy melt state and a cooking state with energy input suitable for cooking food. It signals when a load of food is done. Additionally it enables signals when unwanted temperature conditions exist and turns off heat when temperature goes outside set limits.