Patent ID: 6976892

Claim:
A water-cooled vertical engine comprising: a crankshaft disposed substantially vertically; a connecting rod; a piston connected via the connecting rod to the crankshaft; a cylinder housing the piston in a reciprocating manner; a cylinder block including the cylinder; a cylinder head secured to the cylinder block; a combustion chamber formed by the cylinder head in cooperation with the cylinder and the piston; a head exhaust passage; exhaust passage means for discharging exhaust gas from the combustion chamber to the outside; a cylinder block cooling water jacket around the combustion chamber, the cylinder block cooling water jacket being formed in the cylinder block; a cylinder head cooling water jacket around the combustion chamber, the cylinder head cooling water jacket being formed in the cylinder head and being substantially separate and independent from the cylinder block cooling water jacket; an exhaust passage cooling water jacket formed around the exhaust passage means and substantially separate and independent from the cylinder head cooling water jacket; and a cooling water pump for supplying cooling water to each of the water jackets; wherein the engine further comprises: a first cooling path for supplying cooling water from the cooling water pump to the cylinder block cooling water jacket via the exhaust passage cooling water jacket; a second cooling path for receiving cooling water from the cooling water pump and directly supplying the cooling water to the cylinder head cooling water jacket while bypassing the exhaust passage cooling water jacket; and a thermostat in each of the cylinder block cooling water jacket and the cylinder head cooling water jacket.