Cylinder head cooling structure for an internal combustion engine, including an oil temperature sensor and an oil temperature control system

A vehicle comprising a frame, and an internal combustion engine mounted on the frame, the engine comprising:

• a crankcase;
• a cylinder block joined to an upper side of the crankcase for housing the plurality of cylinders, the cylinders oriented so that a longitudinal axis of a cylinder extends vertically or is inclined substantially forwardly;
• a cylinder head joined to an upper side of the cylinder block;
• an oil cooler located on the vehicle forward of the cylinder block;
• a bypass oil passage that detours around the oil cooler;
• an oil temperature sensor provided on a rear face of said cylinder block above said crankcase, and
• a thermostat used for controlling introduction of oil into the oil cooler or into the bypass oil passage;
• wherein the cylinder head has a spark plug mounting hole formed therein for each cylinder, a plurality of intake ports, and a plurality of exhaust ports, the cylinder head further having a cooling oil jacket formed therein and provided about the periphery of each spark plug mounting hole,
• wherein each of the intake ports and exhaust ports is bifurcated into a fork portion adjacent to a respective cylinder, and
• wherein an oil entry passage is provided adjacent the fork portion of each intake port for conducting oil into said cooling oil jacket, and an oil exit passage is provided adjacent the fork portion of each exhaust port for receiving oil discharged from said cooling oil jacket;
• wherein oil discharged from the cooling oil jackets is directed toward the front side of the cylinder head;
• wherein the thermostat is attached to a front portion of the crankcase;
• and
• wherein during engine operation, after oil that has been discharged to the front side of the engine passes the thermostat, the oil is subsequently delivered to the oil cooler or to the bypass oil passage.

An oil temperature control system for an internal combustion engine on a vehicle, the engine comprising:

• a crankcase;
• a cylinder block joined to an upper side of the crankcase, the cylinder block comprising a cylinder and inclining slightly in the forward direction of the vehicle;
• a cylinder head joined to the cylinder;
• an oil jacket formed in the cylinder head used to cool the cylinder head;
• an oil cooler located on the vehicle forward of the cylinder block;
• a bypass oil passage that detours around the oil cooler;
• and
• a thermostat used for controlling introduction of oil into to one of the oil cooler and the bypass oil passage;
• wherein
• oil discharged from the oil jacket is directed toward the front side of the cylinder head of the engine;
• the thermostat is attached to the front of the crankcase;
• and
• wherein during engine operation, after oil that has been discharged to the front side of the engine passes the thermostat, the oil is subsequently delivered to the oil cooler or to the bypass oil passage.

An oil temperature sensor arrangement structure for an internal combustion engine of a vehicle, wherein the oil temperature sensor arrangement structure comprises an oil temperature sensor,

• wherein said internal combustion engine includes a plurality of cylinders, a crankcase, a cylinder block and a cylinder head, and is arranged on said vehicle such that a cylinder axial line extends vertically or is inclined substantially forwardly,
• wherein an independent oil cooling jacket is provided for each of said cylinders,
• wherein said temperature sensor is provided on a rear face of said cylinder block above said crankcase, and
• wherein said oil temperature sensor arrangement structure comprises
• an oil cooling jacket formed in said cylinder head of the internal combustion engine,
• an oil supply path formed in the engine proximate a rear face of a cylinder for supplying oil to said oil cooling jacket, and
• an oil return path formed in the engine for returning oil from said oil cooling jacket,
• a supply side oil gallery connected to said oil supply path on an upstream side of the oil jackets, and oil sub-paths connected to the individual oil jackets so as to be individually branched from said supply side oil gallery;
• wherein said oil temperature sensor communicates with said oil supply path said oil temperature sensor is provided proximate an entrance portion of said supply side oil gallery from said oil supply path.