Patent ID: 7677019

Claim:
An exhaust circulation lawnmower 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 then returned to the cutter housing as exhaust, the exhaust circulation lawnmower comprising: the cutter housing to which a cutter blade for cutting grass is rotatably provided; and the grass bag provided rearwardly of the cutter housing for storing the grass clippings, wherein a surface area A 1 of a grass clippings discharge opening of the housing and a surface area A 2 of a recirculation opening of the housing have a relationship wherein A 2 is {1/(1−βN) 0.5 } A 1 based on complete recirculation of the carrier air and excluding consideration of entry of outside air into the lawnmower, where A 1 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, A 2 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 a number of bends having an angle of α degrees in the space between the grass clippings discharge opening and the recirculation opening, and β is a pressure loss coefficient for each of the bends.