#$%^&*AU2017201347B220180705.pdf#####LAWN MOWER ABSTRACT A lawn mower (10) comprising a cutter blade (14) rotatable about a rotation shaft (41) extending in a vertical direction； an engine (15) configured to drive the cutter blade (14) through the rotation shaft； a throttle valve (125) provided for the engine (15)； a flap (52) provided for the cutter blade (14), the flap (52) having a flap angle changeable along a horizontal line which is perpendicular to the rotation shaft (41)； an actuator (60) configured to control the flap angle of the flap (52)； a control unit (117) configured to control the actuator (60)； an engine speed detection unit (123) configured to detect a rotation speed of the engine (15)； and a throttle opening angle detection unit (122) configured to detect an opening angle of the throttle valve (125)； wherein the engine (15) has reference rotation speeds set to a predetermined first reference rotation speed and a predetermined second reference rotation speed which is higher than the first reference rotation speed by a predetermined speed； the control unit (117) is configured to control the rotation speed of the engine (15) and the flap (15) angle of the flap (15) by switching operation between a first control mode and a second control mode； in the first control mode, during rotation of the engine at the first reference rotation speed, in a case in which it is determined that a change amount per predetermined time, of the rotation speed of the engine (15) detected by the engine speed detection unit (123) has exceeded a predetermined reference speed change amount, control is implemented in a manner that the rotation speed of the engine (15) is maintained at the second reference rotation speed, and the actuator (60) is controlled to increase the flap angle of the flap (52)； and in the second control mode, during rotation of the engine (15) at the second reference rotation speed, in a case in which it is de
