Smoke exhaust ventilator

The invention discloses a smoke exhaust ventilator. The smoke exhaust ventilator comprises a volute casing, wherein volute-casing air inlets and a volute-casing exhaust outlet communicated with a ventilator exhaust outlet are formed in the volute casing; the volute casing comprises a fixed shell part and movable shell parts; each movable shell part can move between a closing position and an opening position relative to the fixed shell; when the movable shell parts are at the closing positions, the fixed shell part cooperates with the movable shell parts and allows the air in volute-casing air ducts to be exhausted from the volute-casing exhaust outlets; when the movable shell parts are at the opening positions, each of the movable shell parts is staggered relative to the fixed shell part, so that one volute-casing cycling exhaust outlet communicated with ventilator cycling exhaust outlets is formed between each movable shell part and the fixed shell part in a limiting manner; therefore, the air in the volute-casing air ducts is exhausted into a room through the volute-casing cycling exhaust outlets and the ventilator cycling exhaust outlets sequentially. According to the smoke exhaust ventilator disclosed by the invention, when the air is exhausted into the room, the air flowing distance is short, so that the working efficiency of the smoke exhaust ventilator is high.