Exhaust circulation lawnmower

An exhaust circulation lawnmower is disclosed in which grass clippings are sent, along with carrier air, from a cutter housing to a grass bag; the grass clippings are held in the grass bag; and the carrier air is returned to the cutter housing as exhaust. A surface area A1 of a grass clippings discharge opening and a surface area A2 of a recirculation opening have a relationship of A2 {1/(1− N)0.5}A1, where A1 is the surface area of the grass clippings discharge opening through which the grass clippings and carrier air are discharged from the cutter housing to the grass bag, A2 is the surface area of the recirculation opening through which the carrier air is recirculated from the grass bag to the cutter housing, N is the number of bends having an angle of α degrees in the space between the grass clippings discharge opening and the recirculation opening, and is a pressure loss coefficient for each of the bends.