| 摘要 |
A device for improving cooling performance of an EGR cooler is provided to improve the efficiency of the EGR system and to repress nitrogen oxide by adding a device for circulating the compressed air pressurized by an air compressor. An EGR cooler(30) has plural cooling tubes(32) formed in a case(31) connected with an exhaust gas recirculating pipe to pass EGR gas and to exchange heat with peripheral parts and a coolant passage(50) disposed in the case to circulate the coolant. An air chamber(40) is disposed at an inner peripheral surface of the coolant passage with covering the cooling tubes and is connected with an air compressor(60) through an air line(61). An air valve(63) is installed at the air line and opened to insert the residual compressed air left after filling an air tank(62) in operating the air compressor into the air chamber. An overflow valve(64) is installed at the air chamber to keep internal pressure of the air chamber proper and opened to exhaust the pressure to the atmosphere if the compressed air filled in the air chamber is increased over a predetermined value. A regulating valve(65) is disposed at the air chamber and opened if the temperature of the air contained in the air chamber is increased over a predetermined value.
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