Cooling structure and outdoor unit including cooling structure

An outdoor unit, comprising:

• a cooling structure comprising:
• a heat sink to be mounted to a heat generator;
• and
• a duct, which is mounted to the heat sink, and is configured to guide an air flow flowing around the heat sink to the heat sink, and
• a heat exchange,
• wherein the heat sink includes a plurality of heat-radiating fins arranged at an interval,
• wherein the heat sink has an air flow passage to allow the air flow to pass through the air flow passage,
• wherein the duct has a downstream end portion of the duct and an upstream end portion of the duct that is closer to the heat exchange than the downstream end portion of the duct,
• wherein the downstream end portion of the duct is to be mounted to an upstream side of a downstream end portion of the heat sink, and
• wherein the upstream end portion of the duct is to be extended to an upstream side of the air flow beyond an upstream end portion of the heat sink so as to surround a periphery of the upstream end portion of the heat sink,
• wherein the cooling structure further comprising:
• a casing in which the heat generator, the heat sink, and the duct are accommodated;
• and
• an air-sending fan configured to generate the air flow,
• wherein the casing has an inlet port and an exhaust port,
• wherein a peripheral edge portion of the exhaust port includes an annular protruding portion that protrudes to an inner side of the casing
• wherein the annular protruding portion has a downstream end portion of the annular protruding portion and an upstream end portion of the annular protruding portion that is located closer to the heat exchange than the downstream end portion of the annular protruding portion,
• wherein the downstream end portion of the duct is located upstream of the air flow than the upstream end portion of the annular protruding portion,
• wherein the upstream end portion of the annular protruding portion is provided between the downstream end portion of the duct and the downstream end portion of the heat sink,
• wherein the downstream end portion of the duct is located farther from the heat exchange than the upstream end portion of the duct, and
• wherein the downstream end portion of the heat sink is located farther from the heat exchange than the upstream end portion of the heat sink.