US Patent 9021777 Cutter guard for a lawn mower

A cutter guard for a rotating blade of a lawn mower, particularly for a robotic, self-guided or autonomous lawn mower forms a cutting bowl in which the blade is mounted for rotation about a generally vertical axis. The guard comprises a generally planar guard section surrounded by an arcuate section, transverse edges of which define an opening in the cutter guard, which in operation is pointed to the front of the lawn mower, to allow uncut grass to be accessed by the cutting blades. The arcuate section comprises a plurality of apertures.