Importance

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Abstract

A cryogenic freezer apparatus for food products, including a thermally insulated enclosure and conveyor means for conveying products through the enclosure. A cryogen unit in the enclosure produces cryogen vapor near the enclosure entrance, and a blower unit is located in the enclosure adjacent the entrance thereof. The blower unit is selectively reconfigurable in response to a blower control signal to selectively direct cryogen vapor in varying directions, drawing cryogen vapor away from a first portion of the enclosure and blowing cryogen vapor toward a second portion of the enclosure. A photocell unit outside the enclosure, adjacent the entrance thereof, detects cryogen vapor exiting the enclosure entrance and generates at least one sensor output signal in response thereto, being indicative of the amount of cryogen vapor exiting. A control unit is coupled to the photocell unit and to the blower unit for generating a blower control signal in response to the sensor output signal so that, with increasing vapor detected outside the entrance of the enclosure, the blower unit draws cryogen vapor away from the enclosure entrance. Also, upon detecting a decreasing amount of cryogen vapor exiting from the entrance of the enclosure, the blower unit directs less cryogen vapor away from the enclosure entrance to assure that intrusion of the ambient environment through the enclosure entrance is prevented.

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First Claim