Refrigeration control system with self-adjusting defrost interval

Claim 1

A method of adjusting the period of a defrost interval in a refrigerator comprising: electronically detecting a parameter directly relating to and representing the time period of a defrost operation in the refrigerator; comparing said parameter with a source of signals representing predetermined defrost period limits, said period limits comprising a plurality of preselected defrost operation periods including a preferred period and non-preferred periods; generating an output control signal in response to a predetermined relationship between said parameter and said source of signals; and, adjusting the defrost interval in response to said control signal when the defrost operating time falls within a non-preferred period said adjusting comprising setting the interval to a preselected minimum base interval when the defrost operation time period is greater than a preselected maximum non-preferred period; decreasing the interval by a preselected adjustment time period when the defrost operation time period is greater than the preferred period and less than the maximum non-preferred period; repeating the defrost interval when the defrost operation time period falls within the preferred period; and, increasing the interval by the preselected adjustment time period when the defrost operation time period is less than the preferred period, said increasing being limited by a maximum base defrost interval period whereby the defrost interval period is maintained within a preferred preselected time period.

Claim 2

A method of adjusting the period of a defrost interval in a refrigerator comprising: electronically detecting a parameter directly relating to and representing the time period of a defrost operation in the refrigerator; comparing said parameter with a source of signals representing predetermined defrost period limits, said period limits comprising a plurality of preselected defrost operation periods including a preferred period and non-preferred periods; generating an output control signal in response to a predetermined relationship between said parameter and said source of signals; and, adjusting the defrost interval in response to said control signal when the defrost operating time falls within a non-preferred period said adjusting comprising setting the interval to a preselected minimum base interval when the defrost operation time period is greater than a preselected maximum non-preferred period; decreasing the interval by a preselected adjustment time period when the defrost operation time period is greater than the preferred period and less than the maximum non-preferred period; repeating the defrost interval when the defrost operation time period falls within the preferred period; and, increasing the interval by the preselected adjustment time period when the defrost operation time period is less than the preferred period, said increasing being limited by a maximum base defrost interval period whereby the defrost interval period is maintained within a preferred preselected time period.

Claim 3

A method of adjusting the period of a defrost interval in a refrigerator comprising: providing a sensing means for providing an output signal representative of the temperature of a refrigerator compartment; and a thermostat means for providing control signals indicative of the refrigerator compartment; continuously comparing the output and control signals for detecting a parameter directly relating to and representing the time period of a defrost operation in the refrigerator; continuously verifiying the operability of the sensing means and thermostat means; comparing said parameter with a source of signals representing predetermined defrost period limits, said period limits comprising a plurality of preselected defrost operation periods including a preferred period and non-preferred periods; generating an output control signal in response to a predetermined relationship between said parameter and said source of signals; and, adjusting the defrost interval in response to said control signal when the defrost operating time falls within a non-preferred period said adjusting comprising setting the interval to a preselected minimum base interval when the defrost operation time period is greater than a preselected maximum non-preferred period; decreasing the interval by a preselected adjustment time period when the defrost operation time period is greater than the preferred period and less than the maximum non-preferred period; repeating the defrost interval when the defrost operation time period falls within the preferred period; and, increasing the interval by the preselected adjustment time when the defrost operation time period is less than the preferred period, said increasing being limited by a maximum base defrost interval period whereby the defrost interval is maintained within a preferred preselected time period.

Claim 4

A method of adjusting the period of a defrost interval in a refrigerator comprising: providing a sensing means for providing an output signal representative of the temperature of a refrigerator compartment; and a thermostat means for providing control signals indicative of the refrigerator compartment; continuously comparing the output and control signals for detecting a parameter directly relating to and representing the time period of a defrost operation in the refrigerator; continuously verifiying the operability of the sensing means and thermostat means; comparing said parameter with a source of signals representing predetermined defrost period limits, said period limits comprising a plurality of preselected defrost operation periods including a preferred period and non-preferred periods; generating an output control signal in response to a predetermined relationship between said parameter and said source of signals; and, adjusting the defrost interval in response to said control signal when the defrost operating time falls within a non-preferred period said adjusting comprising setting the interval to a preselected minimum base interval when the defrost operation time period is greater than a preselected maximum non-preferred period; decreasing the interval by a preselected adjustment time period when the defrost operation time period is greater than the preferred period and less than the maximum non-preferred period; repeating the defrost interval when the defrost operation time period falls within the preferred period; and, increasing the interval by the preselected adjustment time when the defrost operation time period is less than the preferred period, said increasing being limited by a maximum base defrost interval period whereby the defrost interval is maintained within a preferred preselected time period.