Adaptive defrost system

Claim 1

A method for controlling the defrosting of a heat transfer unit of a temperature conditioning system by initiating a defrost operation when a predetermined amount of frost has accumulated on the unit during a frost accumulation period that occurs between defrost operations, said method being of the type comprising the steps: determining the time required to actually defrost said unit during an actual defrost operation; increasing the frost accumulation period before initiating the next defrost operation if the time to complete the last defrost was less than said desired defrost time period; or decreasing the frost accumulation period before initiating the next defrost operation if the time to complete the last defrost was greater than said desired defrost time period; improved wherein said determining the time to actually defrost said unit comprises the step of determining the time period required to raise the temperature of said heat transfer unit from a first predetermined temperature to a second predetermined temperature.

Claim 2

A method for controlling the defrosting of a heat transfer unit of a temperature conditioning system by initiating a defrost operation when a predetermined amount of frost has accumulated on the unit during a frost accumulation period that occurs between defrost operations, said method being of the type comprising the steps: determining the time required to actually defrost said unit during an actual defrost operation; increasing the frost accumulation period before initiating the next defrost operation if the time to complete the last defrost was less than said desired defrost time period; or decreasing the frost accumulation period before initiating the next defrost operation if the time to complete the last defrost was greater than said desired defrost time period; improved wherein said determining the time to actually defrost said unit comprises the step of determining the time period required to raise the temperature of said heat transfer unit from a first predetermined temperature to a second predetermined temperature.

Claim 7

A system for selectively generating a defrost signal to controllably defrost a heat transfer unit, said system comprising: temperature sensor means for providing indicia of the temperature of said unit; storage means for accessibly storing indicia of a frost accumulation period duration; defrost initiating means, for selectively initiating generation of said defrost control signal to effect defrosting of said heat transfer unit at the expiration of said frost accumulation period; defrost termination means, cooperating with said storage means, for terminating generation of said defrost control signal responsive to the first to occur of: said heat transfer unit attaining a temperature indicative of a defrosted condition; or expiration of said maximum defrost period; means for adjusting said frost accumulation period in accordance with the deviation from a desired value of the time period required to defrost said heat transfer unit; and means, responsive to expiration of said maximum defrost period, for setting said frost accumulation period to a predetermined value.

Claim 8

A system for selectively generating a defrost signal to controllably defrost a heat transfer unit, said system comprising: temperature sensor means for providing indicia of the temperature of said unit; storage means for accessibly storing indicia of a frost accumulation period duration; defrost initiating means, for selectively initiating generation of said defrost control signal to effect defrosting of said heat transfer unit at the expiration of said frost accumulation period; defrost termination means, cooperating with said storage means, for terminating generation of said defrost control signal responsive to the first to occur of: said heat transfer unit attaining a temperature indicative of a defrosted condition; or expiration of said maximum defrost period; means for adjusting said frost accumulation period in accordance with the deviation from a desired value of the time period required to defrost said heat transfer unit; and means, responsive to expiration of said maximum defrost period, for setting said frost accumulation period to a predetermined value.

Claim 10

A system for selectively generating a defrost signal to controllably defrost a heat transfer unit, said system comprising: temperature sensor means for providing indicia of the temperature of said unit; storage means for accessibly storing indicia of a frost accumulation period duration; defrost initiating means, for selectively initiating generation of said defrost control signal to effect defrosting of said heat transfer unit at the expiration of said frost accumulation period; defrost termination means, cooperating with said storage means, for terminating generation of said defrost control signal responsive to the first to occur of: said heat transfer unit attaining a temperature indicative of a defrosted condition; or expiration of said maximum defrost period; and means for determining deviation, from a desired value, of the defrost time period required to increase the temperature of said heat transfer unit from a first predetermined temperature to a second predetermined temperature and adjusting said frost accumulation period in accordance with said deviation.

Claim 11

A system for selectively generating a defrost signal to controllably defrost a heat transfer unit, said system comprising: temperature sensor means for providing indicia of the temperature of said unit; storage means for accessibly storing indicia of a frost accumulation period duration; defrost initiating means, for selectively initiating generation of said defrost control signal to effect defrosting of said heat transfer unit at the expiration of said frost accumulation period; defrost termination means, cooperating with said storage means, for terminating generation of said defrost control signal responsive to the first to occur of: said heat transfer unit attaining a temperature indicative of a defrosted condition; or expiration of said maximum defrost period; and means for determining deviation, from a desired value, of the defrost time period required to increase the temperature of said heat transfer unit from a first predetermined temperature to a second predetermined temperature and adjusting said frost accumulation period in accordance with said deviation.

Claim 20

A system for selectively generating a defrost signal to controllably defrost a heat transfer unit, said system comprising: temperature sensor means for providing indicia of the temperature of said unit; storage means for accessibly storing indicia of a frost accumulation period duration; defrost initiating means, for selectively initiating generation of said defrost control signal to effect defrosting of said heat transfer unit at the expiration of said frost accumulation period; defrost termination means, cooperating with said storage means, for terminating generation of said defrost control signal responsive to the first to occur of: said heat transfer unit attaining a temperature indicative of a defrosted condition; or expiration of said maximum defrost period; means for adjusting said frost accumulation period in accordance with the deviation from a desired value of the time period required to defrost said heat transfer unit and for setting said frost accumulation period to a predetermined value in response to expiration of said maximum defrost period; and timer means, receptive of indicia of time periods communicated thereto, for providing indicia of temporal advancement through said time periods; said defrost initiating means comprising: means, cooperating with said storage means, for selectively communicating indicia of said frost accumulation period duration to said timer means, whereby said timer means provides indicia of temporal advancement through said frost accumulation period; and said defrost termination means including: means for selectively communicating indicia of a maximum defrost time period to said timer means, whereby said timer means provides indicia of temporal advancement through said maximum defrost period.

Claim 21

A system for selectively generating a defrost signal to controllably defrost a heat transfer unit, said system comprising: temperature sensor means for providing indicia of the temperature of said unit; storage means for accessibly storing indicia of a frost accumulation period duration; defrost initiating means, for selectively initiating generation of said defrost control signal to effect defrosting of said heat transfer unit at the expiration of said frost accumulation period; defrost termination means, cooperating with said storage means, for terminating generation of said defrost control signal responsive to the first to occur of: said heat transfer unit attaining a temperature indicative of a defrosted condition; or expiration of said maximum defrost period; means for adjusting said frost accumulation period in accordance with the deviation from a desired value of the time period required to defrost said heat transfer unit and for setting said frost accumulation period to a predetermined value in response to expiration of said maximum defrost period; and timer means, receptive of indicia of time periods communicated thereto, for providing indicia of temporal advancement through said time periods; said defrost initiating means comprising: means, cooperating with said storage means, for selectively communicating indicia of said frost accumulation period duration to said timer means, whereby said timer means provides indicia of temporal advancement through said frost accumulation period; and said defrost termination means including: means for selectively communicating indicia of a maximum defrost time period to said timer means, whereby said timer means provides indicia of temporal advancement through said maximum defrost period.

Claim 26

A system for selectively generating a defrost signal to controllably defrost a heat transfer unit, said system comprising: temperature sensor means for providing indicia of the temperature of said unit; storage means for accessibly storing indicia of a frost accumulation period duration; defrost initiating means, for selectively initiating generation of said defrost control signal to effect defrosting of said heat transfer unit at the expiration of said frost accumulation period; defrost termination means, cooperating with said storage means, for terminating generation of said defrost control signal responsive to the first to occur of: said heat transfer unit attaining a temperature indicative of a defrosted condition; or expiration of said maximum defrost period; means for adjusting said frost accumulation period in accordance with the deviation from a desired value of the time period required to defrost said heat transfer unit; and timer means, receptive of indicia of time periods communicated thereto, for providing indicia of temporal advancement through said time periods; said defrost initiating means comprising: means, cooperating with said storage means, for selectively communicating indicia of said frost accumulation period duration to said timer means, whereby said timer means provides indicia of temporal advancement through said frost accumulation period; and means, responsive to continuous prevalence of conditions not conducive to frost accumulation for a period in excess of a predetermined duration, for restarting advancement through said frost accumulation period in said timer means without generating said defrost control signal; said defrost termination means including: means for selectively communicating indicia of a defrost time period to said timer means, whereby said timer means provides indicia of temporal advancement through said maximum defrost period.

Claim 27

A system for selectively generating a defrost signal to controllably defrost a heat transfer unit, said system comprising: temperature sensor means for providing indicia of the temperature of said unit; storage means for accessibly storing indicia of a frost accumulation period duration; defrost initiating means, for selectively initiating generation of said defrost control signal to effect defrosting of said heat transfer unit at the expiration of said frost accumulation period; defrost termination means, cooperating with said storage means, for terminating generation of said defrost control signal responsive to the first to occur of: said heat transfer unit attaining a temperature indicative of a defrosted condition; or expiration of said maximum defrost period; means for adjusting said frost accumulation period in accordance with the deviation from a desired value of the time period required to defrost said heat transfer unit; and timer means, receptive of indicia of time periods communicated thereto, for providing indicia of temporal advancement through said time periods; said defrost initiating means comprising: means, cooperating with said storage means, for selectively communicating indicia of said frost accumulation period duration to said timer means, whereby said timer means provides indicia of temporal advancement through said frost accumulation period; and means, responsive to continuous prevalence of conditions not conducive to frost accumulation for a period in excess of a predetermined duration, for restarting advancement through said frost accumulation period in said timer means without generating said defrost control signal; said defrost termination means including: means for selectively communicating indicia of a defrost time period to said timer means, whereby said timer means provides indicia of temporal advancement through said maximum defrost period.

Claim 29

A system for selectively generating a defrost signal to controllably defrost a heat transfer unit, said system comprising: temperature sensor means for providing indicia of the temperature of said unit; storage means for accessibly storing indicia of a frost accumulation period duration; defrost initiating means, for selectively initiating generation of said defrost control signal to effect defrosting of said heat transfer unit at the expiration of said frost accumulation period; defrost termination means, cooperating with said storage means, for terminating generation of said defrost control signal responsive to the first to occur of: said heat transfer unit attaining a temperature indicative of a defrosted condition; or expiration of said maximum defrost period; means for adjusting said frost accumulation period in accordance with the deviation from a desired value of the time period required to defrost said heat transfer unit; and temperature sensor means comprising a first thermistor disposed to manifest a resistance value in accordance with the temperature of said unit; means for selectively coupling said first thermistor to a capacitance of known value such that said capacitance is charged through the selectively coupled thermistor; counter means for selectively generating a count; processor means, having an instruction cycle associated therewith, for adjusting said count by a predetermined amount in response to each occurrence of a predetermined number of instruction cycles during the time period required for said capacitance to charge to a predetermined voltage level through said thermistor; a resistance of known value; means for periodically coupling said resistance to said capacitance such that said capacitance is charged through said known resistance; means for developing a calibration count indicative of the time required to charge said capacitance to said predetermined voltage level through said known resistance; and means for varying said predetermined number of instruction cycles in accordance with deviations of said calibration count from a predetermined calibration value.

Claim 30

A system for selectively generating a defrost signal to controllably defrost a heat transfer unit, said system comprising: temperature sensor means for providing indicia of the temperature of said unit; storage means for accessibly storing indicia of a frost accumulation period duration; defrost initiating means, for selectively initiating generation of said defrost control signal to effect defrosting of said heat transfer unit at the expiration of said frost accumulation period; defrost termination means, cooperating with said storage means, for terminating generation of said defrost control signal responsive to the first to occur of: said heat transfer unit attaining a temperature indicative of a defrosted condition; or expiration of said maximum defrost period; means for adjusting said frost accumulation period in accordance with the deviation from a desired value of the time period required to defrost said heat transfer unit; and temperature sensor means comprising a first thermistor disposed to manifest a resistance value in accordance with the temperature of said unit; means for selectively coupling said first thermistor to a capacitance of known value such that said capacitance is charged through the selectively coupled thermistor; counter means for selectively generating a count; processor means, having an instruction cycle associated therewith, for adjusting said count by a predetermined amount in response to each occurrence of a predetermined number of instruction cycles during the time period required for said capacitance to charge to a predetermined voltage level through said thermistor; a resistance of known value; means for periodically coupling said resistance to said capacitance such that said capacitance is charged through said known resistance; means for developing a calibration count indicative of the time required to charge said capacitance to said predetermined voltage level through said known resistance; and means for varying said predetermined number of instruction cycles in accordance with deviations of said calibration count from a predetermined calibration value.

Claim 31

A system for controllably actuating a defrost mechanism associated with a heat transfer unit, said system comprising: temperature sensor means for providing indicia of the temperature of said heat transfer unit; a random access memory, for accessibly storing: indicia of the temperature of said heat transfer unit; indicia of the duration of a frost accumulation period; and a first count, indicative of temporal advancement through a time period; and a processor, said processor comprising: means for selectively initializing said first count such that said first count is indicative of temporal advancement through said frost accumulation period; means for periodically adjusting said first count to account for temporal advancement; means for generating said control signal to actuate said defrost mechanism responsive to said count manifesting expiration of said frost accumulation period; means for selectively initializing said first count such that said first count is indicative of temporal advancement through a defrost operation; means for ceasing to generate said control signal responsive to the first to occur of: the temperature of said heat exchange unit manifesting that said heat exchange unit is in a defrosted condition; or said count manifests that a predetermined maximum defrost period has expired; means for determining the actual time required for said heat transfer unit to attain a defrost condition; and means for adjusting the duration of said frost accumulation period in accordance with the deviation of said actual time from a desired defrost time and for setting said frost accumulation period to a predetermined value in response to expiration of said maximum defrost period.

Claim 32

A system for controllably actuating a defrost mechanism associated with a heat transfer unit, said system comprising: temperature sensor means for providing indicia of the temperature of said heat transfer unit; a random access memory, for accessibly storing: indicia of the temperature of said heat transfer unit; indicia of the duration of a frost accumulation period; and a first count, indicative of temporal advancement through a time period; and a processor, said processor comprising: means for selectively initializing said first count such that said first count is indicative of temporal advancement through said frost accumulation period; means for periodically adjusting said first count to account for temporal advancement; means for generating said control signal to actuate said defrost mechanism responsive to said count manifesting expiration of said frost accumulation period; means for selectively initializing said first count such that said first count is indicative of temporal advancement through a defrost operation; means for ceasing to generate said control signal responsive to the first to occur of: the temperature of said heat exchange unit manifesting that said heat exchange unit is in a defrosted condition; or said count manifests that a predetermined maximum defrost period has expired; means for determining the actual time required for said heat transfer unit to attain a defrost condition; and means for adjusting the duration of said frost accumulation period in accordance with the deviation of said actual time from a desired defrost time and for setting said frost accumulation period to a predetermined value in response to expiration of said maximum defrost period.

Claim 38

A system for regulating the temperature of an area, said system comprising: a compressor, responsive to compressor control signals applied thereto; first and second heat transfer units, fluidically coupled to said compressor, said first heat transfer unit being disposed in said area, said second heat transfer unit being disposed outside of said area; defrost means, responsive to defrost control signals applied thereto, for controllably defrosting said second heat transfer unit; temperature sensor means for providing indicia of the temperature of said second heat transfer unit; storage means for accessibly storing indicia of a frost accumulation period duration; defrost initiating means, for selectively initiating generation of said defrost control signal to effect defrosting of said second heat transfer unit at the expiration of said frost accumulation period; defrost termination means, for terminating generation of said defrost control signal responsive to the first to occur of: said heat transfer unit attaining a temperature indicative of a defrosted condition; or expiration of said maximum defrost period; and means for adjusting said frost accumulation period in accordance with the deviation of the time period required to raise the temperature of said second heat transfer unit from a first predetermined temperature to a second predetermined temperature.

Claim 39

A system for regulating the temperature of an area, said system comprising: a compressor, responsive to compressor control signals applied thereto; first and second heat transfer units, fluidically coupled to said compressor, said first heat transfer unit being disposed in said area, said second heat transfer unit being disposed outside of said area; defrost means, responsive to defrost control signals applied thereto, for controllably defrosting said second heat transfer unit; temperature sensor means for providing indicia of the temperature of said second heat transfer unit; storage means for accessibly storing indicia of a frost accumulation period duration; defrost initiating means, for selectively initiating generation of said defrost control signal to effect defrosting of said second heat transfer unit at the expiration of said frost accumulation period; defrost termination means, for terminating generation of said defrost control signal responsive to the first to occur of: said heat transfer unit attaining a temperature indicative of a defrosted condition; or expiration of said maximum defrost period; and means for adjusting said frost accumulation period in accordance with the deviation of the time period required to raise the temperature of said second heat transfer unit from a first predetermined temperature to a second predetermined temperature.

Claim 42

A system for controllably actuating a defrost mechanism associated with a heat transfer unit, said heat transfer unit being fluidically coupled to a compressor, said compressor including compressor control means, responsive to a control signal selectively applied thereto, for controllably actuating said compressor; said system comprising: temperature sensor means for providing indicia of the temperature of said heat transfer unit; a random access memory, for accessibly storing: indicia of the temperature of said heat transfer unit; indicia of the duration of a frost accumulation period; and a first count, indicative of temporal advancement through a time period; means for selectively applying an AC line signal as said control signal to said compressor control means; means for sensing the operational state of said compressor; and a processor, said processor comprising: means for selectively initializing said first count such that said first count is indicative of temporal advancement through said frost accumulation period; means for periodically adjusting said first count to account for temporal advancement; means for generating said control signal to actuate said defrost mechanism responsive to said count manifesting expiration of said frost accumulation period; means for selectively initializing said first count such that said first count is indicative of temporal advancement through a defrost operation; means for ceasing to generate said control signal responsive to the first to occur of: the temperature of said heat exchange unit manifesting that said heat exchange unit is in a defrosted condition; or said count manifests that a pre-determined maximum defrost period has expired; means for determining the actual time required for said heat transfer unit to attain a defrost condition; means for adjusting the duration of said frost accumulation period in accordance with the deviation of said actual time from a desired defrost time, and for said first accumulation period to a predetermined value in respect to expiration of said maximum defrost period; and means for inhibiting incrementing said first count during periods when said compressor is off; said means for sensing the operational status of said compressor comprising: means for sensing the operational status of said AC line signal; means for sensing the phase of the control signal applied to said compressor control means; and means for generating indicia of compressor operational status in accordance with a comparison of the phases of said AC line signal and the signal applied to said compressor control means.

Claim 43

A system for controllably actuating a defrost mechanism associated with a heat transfer unit, said heat transfer unit being fluidically coupled to a compressor, said compressor including compressor control means, responsive to a control signal selectively applied thereto, for controllably actuating said compressor; said system comprising: temperature sensor means for providing indicia of the temperature of said heat transfer unit; a random access memory, for accessibly storing: indicia of the temperature of said heat transfer unit; indicia of the duration of a frost accumulation period; and a first count, indicative of temporal advancement through a time period; means for selectively applying an AC line signal as said control signal to said compressor control means; means for sensing the operational state of said compressor; and a processor, said processor comprising: means for selectively initializing said first count such that said first count is indicative of temporal advancement through said frost accumulation period; means for periodically adjusting said first count to account for temporal advancement; means for generating said control signal to actuate said defrost mechanism responsive to said count manifesting expiration of said frost accumulation period; means for selectively initializing said first count such that said first count is indicative of temporal advancement through a defrost operation; means for ceasing to generate said control signal responsive to the first to occur of: the temperature of said heat exchange unit manifesting that said heat exchange unit is in a defrosted condition; or said count manifests that a pre-determined maximum defrost period has expired; means for determining the actual time required for said heat transfer unit to attain a defrost condition; means for adjusting the duration of said frost accumulation period in accordance with the deviation of said actual time from a desired defrost time, and for said first accumulation period to a predetermined value in respect to expiration of said maximum defrost period; and means for inhibiting incrementing said first count during periods when said compressor is off; said means for sensing the operational status of said compressor comprising: means for sensing the operational status of said AC line signal; means for sensing the phase of the control signal applied to said compressor control means; and means for generating indicia of compressor operational status in accordance with a comparison of the phases of said AC line signal and the signal applied to said compressor control means.