Patent ID: 8552574

Claim:
A cogeneration apparatus which includes: a power generator for producing electric power using an engine as a power source; an exhaust heat exchanger for effecting a heat exchange using exhaust heat of the engine; a housing accommodating therein the engine, the power generator and the exhaust heat exchanger; and an exhaust duct interconnecting the housing and outdoors, the cogeneration apparatus comprising: an airtight chamber provided within the housing, at least the power generator and the engine being accommodated within the airtight chamber; and an intake duct connected to the airtight chamber for introducing air from outside the housing into the airtight chamber, wherein the exhaust duct is connected to the engine for discharging exhaust gas of the engine, the air introduced through the intake duct cools an interior of the airtight chamber and is also sucked in to an air cleaner of the engine, and the exhaust gas of the engine is discharged directly to outside the airtight chamber through the exhaust duct; wherein the exhaust duct comprises an external duct provided outside the housing and an extension duct provided within the housing, wherein the external duct is constructed as a dual structure comprising a first inner peripheral passage disposed centrally therein and a first outer peripheral passage disposed concentrically with and outside the first inner peripheral passage, and the extension duct is constructed as a dual structure comprising a second inner peripheral passage disposed centrally therein and a second outer peripheral passage disposed concentrically with and outside the second inner peripheral passage, and wherein the first inner peripheral passage and the second inner peripheral passage are used as an exhaust passage for discharging exhaust gas of the engine, while the first outer peripheral passage and the second outer peripheral passage are used as an intake passage for supplying air to the engine.