Engine equipped with supercharger

An engine equipped with a supercharger, comprising:

• a supercharger;
• an oil supply passage that supplies engine oil to a shaft bearing part of the supercharger;
• an oil discharge passage that discharges the engine oil from the shaft bearing part of the supercharger;
• a radiator configured to release heat from engine cooling water circulating therethrough;
• a water-cooling-type oil cooler provided in the oil discharge passage and having an outer cylinder and an inner cylinder and a cooler jacket between the inner cylinder and the outer cylinder;
• an engine cooling fan generating engine cooling air;
• and
• an air path for the engine cooling air,
• wherein:
• the engine oil discharged from the shaft bearing part of the supercharger travels through the inner cylinder and the engine cooling water travels through the cooler jacket, whereby heat of the engine oil in the inner cylinder is released to the engine cooling water in the cooler jacket through a peripheral wall of the inner cylinder, thereby cooling the engine oil, and
• the outer cylinder of the water-cooling-type oil cooler is made of a metal and is at least partially disposed in the air path, whereby an outer circumferential surface of the outer cylinder is exposed to the engine cooling air traveling through the air path, to, in turn, air cool the engine cooling water during passage through the cooler jacket, the engine cooling water subsequently being circulated to the radiator.