Appliance defrosting system and switch means

Claim 2

A defrosting system for an appliance having a circulating airflow over cooling coils and means for supplying coolant to the coils comprising, selectively operable means for defrosting the appliance, means responsive to reduced airflow because of frost buildup on the cooling coils to cause operation of said selectively operable means including a switch, an operating member for the switch which is constructed to move with temperature change positioned in said airflow and heated to a temperature above that of the airflow whereby the airflow cools said member to maintain said member in one position and with a predetermined reduction in airflow causing said member to move to operate said switch, and means for discontinuing operation of the defrosting means.

Claim 3

A defrosting system as defined in claim 1 wherein said means for discontinuing operation of the defrosting means includes a temperature-responsive switch having a normally closed contact in series with said airflow-responsive switch and switchable to a second position at said temperature level to establish normal operation of the appliance.

Claim 4

A defrosting system as defined in claim 4 wherein said temperature-responsive switch is responsive to a temperature below said temperature level to reengage the normally closed contact.

Claim 5

A defrosting system as defined in claim 1 wherein said operating member is constructed of bimetal and electrical means for heating thereof.

Claim 6

A defrosting circuit for a refrigerator or the like having cooling coils, a compressor and fan means for inducing an airflow over the coils, comprising defrosting means, a switch having a normally closed contact in series wth said compressor and fan means, an operating member for the switch constructed of material for movement in response to heat applied thereto and positioned in said airflow, means for applying heat to said operating member in an amount whereby normal airflow dissipates the heat sufficiently to prevent movement thereof and whereby a reduction in airflow permits the heat to shift the operating member and open said normally closed contact and energize said defrosting means.

Claim 7

A defrosting circuit for a refrigerator or the like having cooling coils, a compressor and fan means for inducing an airflow over the coils, comprising defrosting means, a switch having a normally closed contact in series wth said compressor and fan means, an operating member for the switch constructed of material for movement in response to heat applied thereto and positioned in said airflow, means for applying heat to said operating member in an amount whereby normal airflow dissipates the heat sufficiently to prevent movement thereof and whereby a reduction in airflow permits the heat to shift the operating member and open said normally closed contact and energize said defrosting means.

Claim 8

A defrosting circuit as defined in claim 5 and including a temperature-sensing switch which bypasses said airflow-sensing switch to deenergize said defrosting means and condition said fan means and compressor for operation.

Claim 9

A defrosting system for an appliance having means providing a circulating airflow over cooling coils and means for supplying coolant to the coils comprising, selectively operable means for defrosting the appliance, a single pole double throw airflow-sensing switch in said appliance and in circuit with and normally in position to condition said circulating means and the coolant-supplying means for operation and including an operating member of material to change shape in response to temperature changes, means for heating said operating membEr, said operating member being normally cooled by the airflow and responsive to diminished airflow to shift to a second position by heat applied thereto to operate said defrosting means, and a second single pole double throw switch responsive to the temperature in the appliance and having a first position to place said first switch in circuit when the temperature in the appliance is at a low level and a second position to disable said first switch and condition said circulating means and coolant supply means for operation when the temperature in the appliance is at a higher level.

Claim 10

A defrosting system for an appliance having means providing a circulating airflow over cooling coils and means for supplying coolant to the coils comprising, selectively operable means for defrosting the appliance, a single pole double throw airflow-sensing switch in said appliance and in circuit with and normally in position to condition said circulating means and the coolant-supplying means for operation and including an operating member of material to change shape in response to temperature changes, means for heating said operating membEr, said operating member being normally cooled by the airflow and responsive to diminished airflow to shift to a second position by heat applied thereto to operate said defrosting means, and a second single pole double throw switch responsive to the temperature in the appliance and having a first position to place said first switch in circuit when the temperature in the appliance is at a low level and a second position to disable said first switch and condition said circulating means and coolant supply means for operation when the temperature in the appliance is at a higher level.

Claim 11

A system as defined in claim 7 wherein said operating member is of bimetal and is electrically heated.

Claim 12

A system as defined in claim 7 wherein said second switch has a wide differential temperature range and has a double-acting snap switch element with a bimetal operating member, and adjustable components associated with said switch element and bimetal operating member to have said switch element in one or the other of said positions.