JPS6458948A - Range hood - Google Patents

Abstract

PURPOSE:To prevent noise from increasing by preventing the negative pressure in a room from increasing, by providing natural draft into the room from an orifice through a duct, by connecting an opening formed on the upper side of the orifice of a ventilating fan to an opening formed on the top of a hood body by the intermediary of a duct. CONSTITUTION:Smoke generating during cooking is gathered in a hood 6 when an impeller of propeller type 1 is rotated by a motor 4. It is discharged outdoors 10, being sucked by a ventilating fan of propeller type 5. At that time, if the static pressure in a room 14 becomes negative pressure 2mm Aq. lower than the outdoor pressure, the impeller of propeller type 1 is going to stall and noise is going to increase suddenly. But return air 11 from outdoors 10 is returned to the room 14, getting in from the gap between the cylindrical part 12 of an orifice 13 and the frame 3 of a fan body, via the opening 7 on the upper side of an orifice and a duct 9, passing through the opening 8 on the top of a hood 6. Accordingly the static pressure in the room 14 will never become negative pressure lower than 2mm Aq. The ventilating fan of propeller type 5 can be operated under the static pressure between 0-1.7mm Aq., so that noise will never increase abruptly.