Napped surface features for noise reduction in front engine covers

摘要

An engine assembly (10) comprising: a cylinder block (12) defining a plurality of cylinders (14); a plurality of pistons (16) disposed in the plurality of cylinders (14); a crankshaft (18) which drive-connected to the plurality of pistons (16); a cover (30, 130, 230, 330) attached to one end of the block (12) and supporting a crankshaft seal (28) around the crankshaft (18), wherein the cover (30) comprises a knobbed pattern (34, 134, 234) in a surface adjacent to the crankshaft seal (28), characterized in that the knobbed pattern (34, 134, 234) knobs (36, 136, 236a, 236b , 236c, 336) with different sizes.