Control arrangements for clothes driers and clothes driers including such control arrangements
First Claim
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1. A control arrangement for a clothes drier having a drying chamber, means for passing air through the chamber from an inlet to an outlet, and heating means for heating air adjacent said inlet;
- the control arrangement comprising a temperature sensor for location adjacent said outlet, heat regulating means for regulating the heat output of the heating means and responsive to said temperature sensor, and means for monitoring said heat output to switch off the heating means comprising means for producing electrical pulses such that the number of said pulses occuring in a given time interval is a predetermined function of the total said heat output in that time interval, means for counting said pulses, means responsive to said counting means for selecting the commencement of a reference time interval of predetermined duration, means responsive to said counting means for storing a digital value which is a predetermined function of the number of said pulses occuring in said selected reference time interval, said number of pulses occuring in said reference time interval being a reference value, and detection means responsive to the stored digital value and responsive to the counting means for detecting when a drypoint time interval of predetermined duration occurs during which the number of said pulses is less than a predetermined proportion of said reference value, said predetermined proportion corresponding to a predetermined degree of dryness of the clothes.
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Abstract
A clothes drier control circuit includes an electric heater regulated to maintain a constant predetermined temperature difference between the outlet and the ambient air. A digital reference value is stored representing the constant heat output level when a constant rate of evaporation is reached. The eventual reduction of the heat output to a given fraction of the reference value is detected so as to indicate that the clothes have reached a predetermined desired degree of dryness.
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Citations
12 Claims
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1. A control arrangement for a clothes drier having a drying chamber, means for passing air through the chamber from an inlet to an outlet, and heating means for heating air adjacent said inlet;
- the control arrangement comprising a temperature sensor for location adjacent said outlet, heat regulating means for regulating the heat output of the heating means and responsive to said temperature sensor, and means for monitoring said heat output to switch off the heating means comprising means for producing electrical pulses such that the number of said pulses occuring in a given time interval is a predetermined function of the total said heat output in that time interval, means for counting said pulses, means responsive to said counting means for selecting the commencement of a reference time interval of predetermined duration, means responsive to said counting means for storing a digital value which is a predetermined function of the number of said pulses occuring in said selected reference time interval, said number of pulses occuring in said reference time interval being a reference value, and detection means responsive to the stored digital value and responsive to the counting means for detecting when a drypoint time interval of predetermined duration occurs during which the number of said pulses is less than a predetermined proportion of said reference value, said predetermined proportion corresponding to a predetermined degree of dryness of the clothes.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
- 11. In a clothes drier having a drying chamber with an air inlet and an air outlet, means for passing air through the chamber via said inlet and outlet, a temperature sensor located adjacent said outlet, and heating means for heating air flowing through said inlet, the improvement comprising a heat control system for the clothes drier comprising, means responsive to said temperature sensor for regulating the heat output of the heating means, said heat regulating means including switching means coupled to control the heating means and means responsive to the temperature sensor for deriving a train of pulses for controlling the on-off time of the switching means as a function of the outlet air temperature, and means responsive to said train of pulses for monitoring the heat output to switch off the switching means at a predetermined degree of dryness of the clothes in the drying chamber, said heat monitoring means comprising means for producing a number of electric pulses in a given time interval which is a predetermined function of the total heat output in said time interval, means for counting said electric pulses, means responsive to said counting means for selecting the start of a reference time interval of predetermined duration as a function of the number of pulses in said train of pulses that occur in a given initial time interval, storage means coupled to the counting means and to the selecting means for storing a digital reference value determined by the number of pulses that occur in the selected reference time interval, and detection means responsive to said counting means and to said selecting means for generating a control pulse to turn off the switching means at a time corresponding to said predetermined degree of dryness of the clothes.
Specification