Patent ID: 8082893

Claim:
An internal combustion engine, comprising: an oil pump for supplying oil under pressure; a cylinder head forming part of a combustion chamber; a cooling portion formed in said cylinder head and adapted to allow circulating oil to cool heat transmitted from said combustion chamber; an oil cooler for cooling oil; an oil passage routed through said oil cooler, a bypass passage bypassing said oil cooler, and a thermostat for switching oil circulation between said oil passage routed through said oil cooler and said bypass passage bypassing said oil cooler; wherein said thermostat is disposed between said oil pump and said cooling portion, wherein said internal combustion engine includes a transmission chamber provided on the rear side of a cylinder block, with respect to the traveling direction of a vehicle in which said internal combustion engine is mounted, wherein said thermostat is disposed rearward of said cylinder block and above said transmission chamber, wherein said cylinder block and said cylinder head are formed with a bulging portion as part of a cam chain chamber at a cylinder-arrangement direction central portion of said internal combustion engine, wherein said thermostat is provided adjacent to said bulging portion, wherein said thermostat includes a thermostat case disposed on the rear surface portion of said cylinder block and a thermostat valve housed in a thermostat chamber formed in said thermostat case, and wherein said thermostat case has a case main body formed integrally with said cylinder block and a lid portion closing an upper end opening of said case main body.