Fan volute tongue structure used for exhaust hood

The invention provides a fan volute tongue structure used for an exhaust hood. The side, facing a fan air outlet, of a volute tongue is provided with an inwards-concave face. The fan volute tongue structure used for the exhaust hood is characterized in that the volute tongue comprises a front disc, a middle disc and a rear disc, the lower side portions, facing the fan air outlet, of the front disc, the middle disc and the rear disc form a lower inwards-concave face in an integrated mode, the upper side portions, facing the fan air outlet, of the front disc, the middle disc and the rear disc form an upper inwards-concave face impacted by discharged air flow, the upper inwards-concave face and the lower inwards-concave face are joined, and the upper inwards-concave face is gradually inclined in the idler wheel rotating direction from bottom to top in an integrated mode from the joining position with the lower inwards-concave face. The fan volute tongue structure used for the exhaust hood has the advantages that