Range hood unit with fire safeguard fan control system

Claim 2

A range hood unit for installation above a cooking stove to ventilate the heated air, steam and volatile products resulting from the cooking of food, comprising a. an electric-motor-driven fan having an air intake and an exhaust opening, and a grease filter positioned in said air intake opening, b. a first sensor-thermostat disposed within said hood and operative at about 140* F., c. a second sensor-thermostat disposed at the said intake opening and operative at about 240* F., d. and an electric circuit including said fan motor and said first and second-thermostats, arranged to energize said fan motor when the temperature immediately below said hood reaches about 140* F., and to de-energize said fan motor if the temperature of the air at the said intake opening reaches about 240* F., e. whereby said fan operates automatically when cooking is being done, but is shut off automatically in the event of a flash fire or the like in the cooking area.

Claim 3

The structure of claim 1, including a warning signal element in said circuit arranged to be energized upon actuation of said second sensor-thermostat.

Claim 4

A range hood unit for installation above a cooking stove to ventilate the heated air, steam and volatile products resulting from the cooking of food, comprising a. an electric-motor-driven fan, having an air intake and an exhaust opening, and a grease filter positioned in said air intake opening, b. a primary power circuit including said motor and a manually operated speed control switch for said motor, c. an interconnected auxiliary safety power circuit including said motor and a first sensor-thermostat operative at about 140* F., d. said auxiliary circuit including also a second sensor-thermostat operative at about 240* F., e. said first sensor-thermostat being arranged to energize said motor when the temperature of the air immediately below said hood reaches about 140* F. if said manually operated switch is in the off position, f. and said second sensor-thermostat being arranged to de-energize said motor if the temperature at said fan intake opening reaches about 240* F., regardless of the position of said manually operated switch or the action of said first sensor-thermostat, g. whereby said fan may be controlled manually, but will operate automatically when cooking is being done even if said manually operated switch is off, and will be shut off automatically in the event of a flash fire or the like.

Claim 5

A range hood unit for installation above a cooking stove to ventilate the heated air, steam and volatile products resulting from the cooking of food, comprising a. an electric-motor-driven fan, having an air intake and an exhaust opening, and a grease filter positioned in said air intake opening, b. a primary power circuit including said motor and a manually operated speed control switch for said motor, c. an interconnected auxiliary safety power circuit including said motor and a first sensor-thermostat operative at about 140* F., d. said auxiliary circuit including also a second sensor-thermostat operative at about 240* F., e. said first sensor-thermostat being arranged to energize said motor when the temperature of the air immediately below said hood reaches about 140* F. if said manually operated switch is in the off position, f. and said second sensor-thermostat being arranged to de-energize said motor if the temperature at said fan intake opening reaches about 240* F., regardless of the position of said manually operated switch or the action of said first sensor-thermostat, g. whereby said fan may be controlled manually, but will operate automatically when cooking is being done even if said manually operated switch is off, and will be shut off automatically in the event of a flash fire or the like.

Claim 6

The structure of claim 3, wherein said exhaust opening is arranged to be connected to an exhaust duct, wherein said manually operated speed control switch is a solid state electronic switch having infinitely variable settings between its low and high speed limits, and wherein said auxiliary circuit also includes a warning signal element arranged to be actuated by said second sensor-thermostat.

Claim 7

The structure of claim 3, wherein said hood is provided with a vent orifice connected to said exhaust opening, through which air is returned to the room, a coated spun glass fiber filter, and an activated charcoal filter in said air intake opening to remove smoke, grease and food odors from the air before returning it to the room; wherein said manually operated switch is a solid state electronic switch having infinitely variable settings between its low and high speed limits, and wherein said auxiliary circuit includes also a warning signal element arranged to be actuated by said second sensor-thermostat.

Claim 8

The structure of claim 1, wherein said sensor-thermostats are of the self-resetting type, said first one resetting itself at about 125* F., and said second one at about 200* F.