Patent ID: 7690367

Claim:
An internal combustion engine comprising: a crankcase; a cylinder head disposed above the crankcase; a cylinder head cover attached to cover an upper side of the cylinder head; an ignition plug provided with a plug part inserted into the cylinder head and a plug cap covering the plug part and disposed outside the cylinder head cover; wherein the cylinder head cover includes a substantially U-shaped gas passage arranged so as to surround the plug cap of the ignition plug as viewed from an insertion side of the ignition plug, the gas passage arranged to allow fuel gas containing oil to flow in from the crankcase; the gas passage includes: a first passage and a second passage spaced a predetermined gap apart from each other so as to interpose the ignition plug therebetween; and a third passage formed in a predetermined direction and adjacent to the ignition plug to couple respective portions of the first passage and the second passage which extend in a direction crossing the predetermined direction; and a gas flow-in port provided in the first passage and disposed away from the third passage to allow the fuel gas containing oil to flow into the gas passage via the first passage from the crankcase; the gas passage of the cylinder head cover includes a plurality of partition walls provided inside the gas passage; a first partition wall of the plurality of partition walls extends between the first passage and the third passage and a second partition wall of the plurality of partition walls extends between the second passage and the third passage; the plurality of partition walls are arranged to restrain an increase in a flow rate of blow-by gas flowing in the first, second, and third passages; and each of the first partition wall and the second partition wall extends around a hole arranged to receive a member to be attached to the cylinder head cover.