Patent GB-1501272-A (GB)
Title: Multiple tier oven
IPC: F24C7/04
Filed: 1975-07-28
Abstract: 1501272 Multiple tier oven BLACK BODY CORP 28 July 1975 [6 May 1975] 31415/75 Heading A2A [Also in Divisions B8 F4 and H2]  A multiple tier oven comprises a plurality of oven chambers, each oven chamber having a floor extending outside the chamber to provide a serving surface continuous with the floor, and a conveyor for moving articles to be heated along the surface into and out of the chamber. In the form shown, the oven includes a frame structure of channel-sectioned and tubular bars, to which the remaining components of the oven are secured. Five oven chambers 5 each comprise an inlet 85, an outlet 86, a heat-resistant glass floor 71, removable front closure panels 68 and 99, and removable heat insulated back panels 80 common to all the chambers, and each include four electrically heated infrared radiating panels 65 arranged side by side from one end to the other end of the chamber. Each panel 80 includes a recess 81 which co-operates with an opening p in a top panel 76 to provide common exhaust passages for the chambers. The floors 71 are bounded adjacent the inlets and outlets by angle irons 57 which project forwards beyond the oven chambers to support adjacent edges of outer sections 87, 88 of the serving surfaces and of removable central sections 89 thereof. Articles to be heated which are passed along the serving surfaces and through the oven chambers by a conveyor system C or C' are heated by the panels 65 both in and immediately below the respective chambers. The conveyor system C' comprises endless chain conveyors 115 to 119, shafts 150, 163, 173 for independently driving the conveyor 115, the conveyors 116, 117 and the conveyors 118, 119 respectively, and a non-rotatable shaft 191 which is movably mounted to ad just the tension of the conveyors. In the conveyor system C of Fig. 1, all the conveyors are driven by a common variable speed shaft 102 and shaft 191 is replaced by an idler shaft 126. Articles to be heated are carried through the oven chambers by arcuate sweep arms 132 or pans (240, Fig. 22) releasably attached to the chain conveyors. The electrical heating elements of the four panels 65 in each oven chamber S are arranged in two pairs connected in parallel, the elements in each pair being connected in series, and are actuatable independently of the elements in the other panels 65, apart from the panels below and in the lowest chamber S, which are simultaneously operable. Thus five sets of elements are independently controlled by five contactor coils (227, Fig. 25), in turn actuated by five solid state controllers responsive to thermocouples (235) which are adjustable by potentiometers (236). Each thermocouple is located immediately below one of the panels 65 in the corresponding oven S. Each set of heating elements is protected by its own set of fuses. When a demand for heat is sensed by a controller (234) via the corresponding thermocouple (235) a thermally-operated contact (233) closes to energise the corresponding coil (227) and thereby close an associated set of contacts (215) to energise the corresponding panels 65. Each controller (234) is of the time-proportioning type i.e. current for heating contacts (233) is switched on and off during each A.C. cycle. A drive motor for shaft 102 may be connected to a variable autotransformer (238).