초록 ▼

A refrigeration system having an improved defrost control including a thermal relay, a bimetal thermostat, and a thick film/hybrid microelectronic element responsive to cumulative humidity of the refrigerated air comprising a moisture sensor/cumulator portion and a control circuit portion on a ceram

A refrigeration system having an improved defrost control including a thermal relay, a bimetal thermostat, and a thick film/hybrid microelectronic element responsive to cumulative humidity of the refrigerated air comprising a moisture sensor/cumulator portion and a control circuit portion on a ceramic substrate. The sensor/cumulator absorbs water vapor at a rate proportional to the relative humidity of the refrigerated air and activates a heater element of the thermal relay to initiate a defrost period. The element is reset by thermally removing a preselected amount of the absorbed water vapor. The defrost period is terminated by a bimetal thermostat. Alternatively, a thermal responsive resistor may be included in the control circuit to terminate the defrost period.

대표청구항 ▼

Improved control means adapted to be responsive to humidity conditions of refrigerated air in a refrigeration system for controlling the operation of the refrigeration system defrost means, comprising: moisture sensing and accumulating means defining a variable electrical resistance varying as an in

Improved control means adapted to be responsive to humidity conditions of refrigerated air in a refrigeration system for controlling the operation of the refrigeration system defrost means, comprising: moisture sensing and accumulating means defining a variable electrical resistance varying as an inverse function of the amount of moisture absorbed thereby; means defining a closed chamber confronting said moisture sensing and accumulating means; circuit means responsive to said variable resistance including a thermal relay having a heater element and a switch for controlling the defrosting operation, and means responsive to said resistance reaching a preselected low resistance for actuating said heater element; and means providing controlled communication between said chamber and the refrigerated air including absorption means spaced from said moisture sensing and accumulating means for absorbing moisture from the refrigerated air for retarding transfer of moisture to said moisture sensing and accumulating means and thereby delaying the dropping of said resistance until a preselected total amount of moisture has been absorbed from said refrigerated air by said moisture sensing and accumulating means and said absorption means.