Two-zone hot air oven for food-loaded cartridges

Claim 1

A hot-air oven for heating pre-cooked meals which are initially cold to an elevated service temperature level suitable for diners, said oven comprising: A. an annular array of cartridges each formed by an open carton whose walls have holes therein and a stack of trays containing said pre-cooked meals nested in said carton, the carton walls of said array defining the boundary of a hollow center core; B. means including a heater assembly to circulate heated air through said core, through a flow restriction and then around said array of cartridges to produce a toroidal air flow pattern enveloping said array, a portion of the heated air in said core being forced by said restriction to pass through the holes of the carton to heat the food in the trays; C. means to continuously rotate said array about said core; and D. an arcuate shield conforming to the boundary of said core to block the flow of heated air into said carton holes and to effectively divide said oven into a hot zone which includes said shield and a non-shielded extra-hot zone whereby during each cycle of rotation in the course of a heat-up phase, the trays in each carton pass successively through said zones, the temperature in said extra-hot zone being well above said service temperature level whereby the rate of heat transfer, which depends on the temperature differential between the existing food temperature and the heating temperature, remains rapid throughout the course of raising the food temperature from its initial to its elevated service temperature level.