Demand defrost control system

Claim 2

Means controlling defrost cycles of at least one refrigeration unit having defrost and refrigeration means in response to the demand constraint of an ambient parameter, comprising: transducer means sensing said ambient parameter and providing a variable speed drive output as a function thereof; control means driven by said drive output; constant speed drive means; first means responsive to said control means energizing said constant speed drive means for a first predetermined interval; second means responsive to said constant speed drive means maintaining the latter energized for a second predetermined interval; and third means responsive to said constant speed drive means actuating said defrost means and precluding actuation of said refrigeration means for a third predetermined interval.

Claim 3

The invention defined in claim 1, wherein said ambient parameter comprises relative humidity.

Claim 4

The invention defined in claim 1, wherein said transducer means includes ambient parameter sensing means, variable frequency oscillator means providing a variable frequency output as a function of said aMbient parameter, and variable speed motor means responsive to said variable frequency output comprising said variable speed drive output.

Claim 5

The invention defined in claim 3, wherein said ambient parameter comprises relative humidity; and said ambient parameter sensing means comprises variable impedance means responsive to changes in relative humidity.

Claim 6

The invention defined in claim 1, wherein said control means comprises periodic switch actuating means; said first means comprises first switch means; said second means comprises second switch means in parallel with said first switch means and cam means contrlling same, said cam means being driven by said constant speed drive means; and said third means comprises third and fourth complimentary switch means energizing and de-energizing, respectively, said defrost means and said refrigeration means and vice-versa.

Claim 7

The invention defined in claim 5, wherein said ambient parameter comprises relative humidity.

Claim 8

The invention defined in claim 5, wherein said transducer means includes ambient parameter sensing means, variable frequency oscillator means providing a variable frequency output as a function of said ambient parameter, and variable speed motor means responsive to said variable frequency output comprising said variable speed drive output.

Claim 9

The invention defined in claim 7, wherein said ambient parameter comprises relative humidity; and said ambient parameter sensing means comprises variable impedance means responsive to changes in relative humidity.

Claim 10

The invention defined in claim 1, wherein said defrost controlling means further includes: override means responsive to an internal parameter of a said refrigeration unit constraining said third means to deactuate said defrost means and actuate said refrigeration means prior to the expiration of said third predetermined interval in response to a predetermined value of said internal parameter.

Claim 11

The invention defined in claim 9, wherein said ambient parameter comprises relative humidity.

Claim 12

The invention defined in claim 9, wherein said transducer means includes ambient parameter sensing means, variable frequency oscillator means providing a variable frequency output as a function of said ambient parameter, and variable speed motor means responsive to said variable frequency output comprising said variable speed drive output.

Claim 13

The invention defined in claim 11, wherein said ambient parameter comprises relative humidity; and said ambient parameter sensing means comprises variable impedance means responsive to changes in relative humidity.

Claim 14

The invention defined in claim 9, wherein said control means comprises periodic switch actuating means; said first means comprises first switch means; said second means comprises second switch means in parallel with said first switch means and cam means controlling same, said cam means being driven by said constant speed drive means; and said third means comprises third and fourth complimentary switch means energizing and de-energizing, respectively, said defrost means and said refrigeration means and vice-versa.

Claim 15

The invention defined in claim 13, wherein said ambient parameter comprises relative humidity.

Claim 16

The invention defined in claim 13, wherein said transducer means includes ambient parameter sensing means, variable frequency oscillator means providing a variable frequency output as a function of said ambient parameter, and variable speed motor means responsive to said variable frequency output comprising said variable speed drive output.

Claim 17

The invention defined in claim 15, wherein said ambient parameter comprises relative humidity; and said ambient parameter sensing means comprises variable impedance means responsive to changes in relative humidity.

Claim 18

Means controlling defrost cycles of at least one refrigeration unit having defrost and refrigeration means in response to the demand constraint of an ambieNt parameter, comprising: variable speed motor means having means for providing a defrost initiation constraint at periodic intervals varied as a function of the value of said ambient parameter; constant speed motor means responsive to said defrost initiation constraint initiating actuation of said defrost means to the exclusion of said refrigeration means for a predetermined maximum interval; and said defrost means including override means for deactuating and actuating said refrigeration means prior to the expiration of said predetermined interval in response to an internal parameter of said refrigeration unit.

Claim 19

Means controlling defrost cycles of at least one refrigeration unit having defrost and refrigeration means in response to the demand constraint of an ambieNt parameter, comprising: variable speed motor means having means for providing a defrost initiation constraint at periodic intervals varied as a function of the value of said ambient parameter; constant speed motor means responsive to said defrost initiation constraint initiating actuation of said defrost means to the exclusion of said refrigeration means for a predetermined maximum interval; and said defrost means including override means for deactuating and actuating said refrigeration means prior to the expiration of said predetermined interval in response to an internal parameter of said refrigeration unit.

Claim 20

The invention defined in claim 17, wherein said constant speed means includes sustaining and slave means indexing same to a ready condition for response to said defrost initiation constraint prior to the end of the current one of said periodic intervals.

Claim 21

The invention defined in claim 17, wherein said ambient parameter comprises relative humidity.

Claim 22

The invention defined in claim 18, wherein said ambient parameter comprises relative humidity.

Claim 23

Means controlling defrost initiation cycles of a plurality of refrigeration units, each such unit having refrigeration and defrost means, in response to the demand constraint of an ambient parameter common to said units, comprising: variable speed motor means including means for providing defrost initiation constraints for each of said units at staggered periodic intervals to substantially preclude simultaneous initiation of defrost cycles in two or more of said units, said periodic intervals being varied as a function of the value of said ambient parameter; constant speed motor means in each of said units responsive to respective defrost initiation constraints from said variable speed means initiating actuation of said defrost means to the exclusion of said refrigeration means in each of said units for a predetermined maximum interval; and override means in each of said units for deactuating said defrost means and actuating said refrigeration means in a said unit prior to the expiration of said predetermined interval in response to an internal parameter of the corresponding said unit.

Claim 24

Means controlling defrost initiation cycles of a plurality of refrigeration units, each such unit having refrigeration and defrost means, in response to the demand constraint of an ambient parameter common to said units, comprising: variable speed motor means including means for providing defrost initiation constraints for each of said units at staggered periodic intervals to substantially preclude simultaneous initiation of defrost cycles in two or more of said units, said periodic intervals being varied as a function of the value of said ambient parameter; constant speed motor means in each of said units responsive to respective defrost initiation constraints from said variable speed means initiating actuation of said defrost means to the exclusion of said refrigeration means in each of said units for a predetermined maximum interval; and override means in each of said units for deactuating said defrost means and actuating said refrigeration means in a said unit prior to the expiration of said predetermined interval in response to an internal parameter of the corresponding said unit.

Claim 25

The invention defined in claim 21, wherein each said constant speed means includes sustaining and slave means indexing same to a ready condition for response to the corresponding ones of said defrost initiation constraints prior to the end of each corresponding current one of said periodic intervals.

Claim 26

The invention defined in claim 21, wherein said ambient parameter comprises relative humidity.

Claim 27

The invention defined in claim 22, wherein said ambient parameter comprises relative humidity.

Claim 28

Means controlling defrost cycles of a plurality of refrigeration units, each such unit having refrigeration and defrost means, in response to the demand constraint of an ambient parameter common to said units, comprising: transducer means common to said units sensing said ambient parameter and providing a variable speed drive output as a function thereof; control means common to said units driven by said drive output and providing defrost initiation constraints for each of said units at staggered periodic intervals to substantially preclude simultaneous initiation of defrost cycles in two or more of said units, said periodic intervals being varied as a function of the value of said ambient parameter; constant speed drive means in each of said units; first means in each of said units, responsive to correlated ones of said periodic defrost initiation constraints, energizing the correlated one of said constant speed drive means for a first predetermined interval; second means in each of said units responsive to the correlated one of said constant speed drive means maintaining the latter energized for a second predetermined interval; and third means in each of said units responsive to the correlated one of said constant speed drive means actuating the correLated one of said defrost means and precluding actuation of the correlated one of said refrigeration means for a third predetermined interval.

Claim 29

Means controlling defrost cycles of a plurality of refrigeration units, each such unit having refrigeration and defrost means, in response to the demand constraint of an ambient parameter common to said units, comprising: transducer means common to said units sensing said ambient parameter and providing a variable speed drive output as a function thereof; control means common to said units driven by said drive output and providing defrost initiation constraints for each of said units at staggered periodic intervals to substantially preclude simultaneous initiation of defrost cycles in two or more of said units, said periodic intervals being varied as a function of the value of said ambient parameter; constant speed drive means in each of said units; first means in each of said units, responsive to correlated ones of said periodic defrost initiation constraints, energizing the correlated one of said constant speed drive means for a first predetermined interval; second means in each of said units responsive to the correlated one of said constant speed drive means maintaining the latter energized for a second predetermined interval; and third means in each of said units responsive to the correlated one of said constant speed drive means actuating the correLated one of said defrost means and precluding actuation of the correlated one of said refrigeration means for a third predetermined interval.

Claim 30

The invention defined in claim 25, wherein said ambient parameter comprises relative humidity.

Claim 31

The invention defined in claim 25, wherein said transducer means includes ambient parameter sensing means, variable frequency oscillator means providing a variable frequency output as a function of said ambient parameter, and variable speed motor means responsive to said variable frequency output comprising said variable speed drive output.

Claim 32

The invention defined in claim 27, wherein said ambient parameter comprises relative humidity; and said ambient parameter sensing means comprises variable impedance means responsive to changes in relative humidity.

Claim 33

The invention defined in claim 25, wherein said control means comprises a plurality of periodic switch actuating means corresponding one to each said refrigeration unit; said first means comprises first switch means; said second means comprises second switch means in parallel with said first switch means and cam means controlling same, said cam means being driven by the correlated one of said constant speed drive means; and said third means comprises third and fourth complimentary switch means energizing and de-energizing, respectively, the correlated ones of said defrost and refrigeration means and vice-versa.

Claim 34

The invention defined in claim 29, wherein said ambient parameter comprises relative humidity.

Claim 35

The invention defined in claim 29, wherein said transducer means includes ambient parameter sensing means, variable frequency oscillator means providing a variable frequency output as a function of said ambient parameter, and variable speed motor means responsive to said variable frequency output comprising said variable speed drive output.

Claim 36

The invention defined in claim 31, wherein said ambient parameter comprises relative humidity; and said ambient parameter sensing means comprises variable impedance means responsive to changes in relative humidity.

Claim 37

The invention defined in claim 25, wherein said defrost controlling means further includes, in each said unit: override means responsive to an internal parameter of the correlated one of said units constraining the correlated one of said third means to deactuate and actuate, respectively, the correlated ones of said defrost and refrigeration means prior to the expiration of said third predetermined interval in response to a predetermined value of said internal parameters.

Claim 38

The invention defined in claim 33, wherein said ambient parameter comprises relative humidity.

Claim 39

The invention defined in claim 33, wherein said transducer means includes ambient parameter sensing means, variable frequency oscillator means providing a variable frequency output as a function of said ambient parameter, and variable speed motor means responsive to said variable frequency output comprising said variable speed drive output.

Claim 40

The invention defined in claim 35, wherein said ambient parameter comprises relative humidity; and said ambient parameter sensing means comprises variable impedance means responsive to changes in relative humidity.

Claim 41

The invention defined in claim 33, wherein said control means comprises a plurality of periodic switch actuating means corresponding one to each said refrigeration unit; said first means comprises first switch means; said second means comprises second switch means in parallel with said first switch means and cam means cntrolling same, said cam means being driven by the correlated one of said constant speed drive means; and said third means comprises third and fourth complimentary switch means energizing and de-energizing, respectively, the correlated ones of said defrost and refrigeration means and vice-versa.

Claim 42

The invention defined in claim 37, wherein said ambient parameter comprises relative Humidity.

Claim 43

The invention defined in claim 38, wherein said transducer means includes ambient parameter sensing means, variable frequency oscillator means providing a variable frequency output proportional to said ambient parameter, and variable speed motor means responsive to said variable frequency output comprising said variable speed drive output.

Claim 44

The invention defined in claim 39, wherein said ambient parameter comprises relative humidity; and said ambient parameter sensing means comprises variable impedance means responsive to changes in relative humidity.

Claim 45

Means controlling defrost cycles of at least one refrigeration unit having defrost and refrigeration means in response to the demand constraint of an ambient parameter, comprising: transducer means sensing said ambient parameter and providing a variable speed drive output as a function thereof; control means driven by said drive output; constant speed drive means; first means responsive to said control means energizing said constant speed drive means for a first predetermined interval; second means responsive to said constant speed drive means maintaining the latter energized for a second predetermined interval; and third means responsive to said constant speed drive means actuating said defrost means and precluding actuation of said refrigeration means for a third predetermined interval; and by-pass means selectively disabling said first and second means, constraining said constant speed means to drive continuously and control said defrost and refrigeration means as a function of time and said third means.

Claim 46

Means controlling defrost cycles of at least one refrigeration unit having defrost and refrigeration means in response to the demand constraint of an ambient parameter, comprising: transducer means sensing said ambient parameter and providing a variable speed drive output as a function thereof; control means driven by said drive output; constant speed drive means; first means responsive to said control means energizing said constant speed drive means for a first predetermined interval; second means responsive to said constant speed drive means maintaining the latter energized for a second predetermined interval; and third means responsive to said constant speed drive means actuating said defrost means and precluding actuation of said refrigeration means for a third predetermined interval; and by-pass means selectively disabling said first and second means, constraining said constant speed means to drive continuously and control said defrost and refrigeration means as a function of time and said third means.

Claim 47

The invention defined in claim 41, wherein said defrost controlling means further includes: override means responsive to an internal parameter of a said refrigeration unit constraining said third means to deactuate said defrost means and actuate said refrigeration means prior to the expiration of said third predetermined interval in response to a predetermined value of said internal parameter.

Claim 48

Means controlling defrost cycles of a plurality of refrigeration units, each such unit having refrigeration and defrost means, in response to the demand constraint of an ambient parameter common to said units, comprising: transducer means common to said units sensing said ambient parameter and providing a variable speed drive output as a function thereof; control means common to said units driven by said drive output and providing defrost initiation constraints for each of said units at staggered periodic intervals to substantially preclude simultaneous initiation of defrost cycles in two or more of said units, said periodic intervals being varied as a function of the value of said ambient parameter; constant speed drive means in each of said units; first means in each of said units, responsive to correlated ones of said periodic defrost initiation constraints, energizing the correlated one of said constant speed drive means for a first predetermined interval; second means in each of said units responsive to the correlated one of said constant speed drive means maintaining the latter energized for a second predetermined interval; third means in each of said units responsive to the correlated one of said constant speed drive means actuating the correlated one of said defrost means and precluding actuation of the correlated one of said refrigeration means for a third predetermined interval; and by-pass means in each of said units selectively disabling correlated ones of said first and second means, constraining the correlated one of said constant speed means to drive continuously and control the correlated ones of said defrost and refrigeration means as a function of time and said third means.

Claim 49

Means controlling defrost cycles of a plurality of refrigeration units, each such unit having refrigeration and defrost means, in response to the demand constraint of an ambient parameter common to said units, comprising: transducer means common to said units sensing said ambient parameter and providing a variable speed drive output as a function thereof; control means common to said units driven by said drive output and providing defrost initiation constraints for each of said units at staggered periodic intervals to substantially preclude simultaneous initiation of defrost cycles in two or more of said units, said periodic intervals being varied as a function of the value of said ambient parameter; constant speed drive means in each of said units; first means in each of said units, responsive to correlated ones of said periodic defrost initiation constraints, energizing the correlated one of said constant speed drive means for a first predetermined interval; second means in each of said units responsive to the correlated one of said constant speed drive means maintaining the latter energized for a second predetermined interval; third means in each of said units responsive to the correlated one of said constant speed drive means actuating the correlated one of said defrost means and precluding actuation of the correlated one of said refrigeration means for a third predetermined interval; and by-pass means in each of said units selectively disabling correlated ones of said first and second means, constraining the correlated one of said constant speed means to drive continuously and control the correlated ones of said defrost and refrigeration means as a function of time and said third means.

Claim 50

The invention defined in claim 43, wherein said defrost controlling means further includes, in each said unit: override means responsive to an internal parameter of the correlated one of said units constraining the correlated one of said third means to deactuate and actuate, respectively, the correlated ones of said defrost and refrigeration means prior to the expiration of said third predetermined interval in response to a predetermined value of said internal parameters.

Claim 51

Means controlling defrost initiation cycles of a plurality of refrigeration units, each such unit having refrigeration and defrost means, in response to the demand constraint of an ambient parameter common to said units, comprising: variable speed means providing defrost initiation constraints for each of said units at staggered periodic intervals to substantially preclude simultaneous initiation of defrost cycles in two or more of said units, said periodic intervals being varied as a function of the value of said ambient parameter; and constant speed means in each of said units responsive to respective defrost initiation constraints from said variable speed means initiating actuation of said defrost means to the exclusion of said refrigeration means in each of said units for a predetermined maximum interval.

Claim 52

Means controlling defrost initiation cycles of a plurality of refrigeration units, each such unit having refrigeration and defrost means, in response to the demand constraint of an ambient parameter common to said units, comprising: variable speed means providing defrost initiation constraints for each of said units at staggered periodic intervals to substantially preclude simultaneous initiation of defrost cycles in two or more of said units, said periodic intervals being varied as a function of the value of said ambient parameter; and constant speed means in each of said units responsive to respective defrost initiation constraints from said variable speed means initiating actuation of said defrost means to the exclusion of said refrigeration means in each of said units for a predetermined maximum interval.

Claim 53

The invention defined in claim 45, wherein said constant speed means includes sustaining and slave means indexing same to a ready condition for response to said defrost initiation constraint prior to the end of the current one of said periodic intervals.

Claim 54

The invention defined in claim 46, wherein said ambient parameter comprises relative humidity.

Claim 55

The invention defined in claim 45, wherein said ambient parameter comprises relative humidity.