Patent ID: 8214086

Claim:
A retractable fan cooling system for an electronics enclosure, the system comprising: at least one cooling fan coupled to an electronics enclosure having a heat sink; and a fan positioning mechanism coupled to the at least one cooling fan; wherein when a temperature inside the electronics enclosure is less than a first temperature, the positioning mechanism places the at least one cooling fan into a retracted position that does not inhibit a natural convective air flow across the heat sink; and wherein when the temperature inside the enclosure is greater than a second temperature, the positioning mechanism places the at least one cooling fan into an engaged position that produces a forced air flow across the heat sink; wherein the fan positioning mechanism further comprises: at least one thermally activated spring coupled to the at least one cooling fan; and at least one counter-spring coupled to the at least one cooling fan; wherein when the at least one thermally activated spring is below a activation temperature, the at least one counter-spring applies a first force to the at least one cooling fan that places the at least one cooling fan into the retracted position; and wherein when the at least one thermally activated spring is not below the activation temperature, the at least one thermally activated spring applies a second force to the at least one cooling fan that counters the first force applied by the at least one counter-spring.