Patent GB-989824-A (GB)
Title: Combined fume extraction unit and cooker
IPC: F24C15/20
Filed: 1963-01-22
Abstract: 989,824. Withdrawing objectionable fumes. G. J. B. CARNE. Jan. 20, 1964 [Jan. 22, 1963], No. 2774/63. Headings F4V and F4W. A fume extraction unit combined with a domestic cooker comprises a fume collection hood disposed over the cooker hot plate, and a fume duct communicating with the hood in the neighbourhood of its apex (and extending downwardly therefrom) and provided with an extraction fan at or near its lower end. In Fig. 1, one embodiment is shown in conjunction with a cooker which includes an oven 2, a lower compartment 3, and a grill 4 supported above a hot plate 1 by a structure 5. A supporting back plate 19 of a hood 7 is bolted to the structure 5 and may extend down to a splash back 6a as indicated by broken lines 19A. As shown in Fig. 2, the hood comprises side walls 8 and front and rear walls 8a and 8b respectively, enclosing a rectangular area at least as great as the area of the hotplate 1. Spaced from and parallel to one side of the hood roof 9, which has a central ridge 10, is a triangular sheet 11 which, together with a vertical sheet (not shown) joining edge 14 to the roof, forms a funnel-shaped fume inlet to a duct 15. The duct 15 passes down the side of the cooker and through the floor 16 to a ventilation space wherein an air extraction fan 18 urges fumes to the outside atmosphere or into an existing fume extraction duct 15A, in which latter case a valve 15B is provided to prevent blow-back of fumes. The hood components and/or the duct 15 may be of metal or heat-resistant plastics, and the hood roof may be domed, of cylindrical section, or rise to a central peak. In an alternative embodiment, Fig. 3 (not shown), instead of sheet 11, a ceiling member is secured to the front and rear hood walls to form two slots between its free edges and the roof, which slots taper towards the rear of the hood. The fume duct partly supports the hood, is secured to the back of the cooker, and extends into the lower cooker compartment which may be sound insulated and wherein is located the fan. An extra inlet to the duct may be provided above a ventilation outlet of the oven. In two alternative hood constructions, Figs. 4a-5b (not shown), a longitudinally slotted tube positioned near the hood apex constitutes a fume outlet. In another embodiment, Figs. 6 and 7 (not shown), the hood is supported by a back plate fixed to a base plate on which a cooker stands. In yet another embodiment, Figs. 8-10 (not shown), the hood is supported by a telescopic duct which in turn is carried by a U-shaped base, the web member of which is also telelcopic. With any of the above embodiments, the fan may be automatically switched on when a heating element is energized. In the case of an electric cooker, this is effected by a relay circuit. For gas cookers, a pressure-sensitive switch is fitted to the gas tap side of a gas pressure governor and is arranged to operate the fan when a fall in gas pressure corresponding to a gas tap being turned on occurs. At the same time, this switch may energize electric igniter elements for the burners. Alternatively, an opening near the ridge 10 of the hood may be provided with a spring-biased flap which is normally held open to allow gases within the hood to escape when the flap is inoperative. When the flap is closed, the fan is automatically energized.