| 摘要 |
PURPOSE:To improve the operation efficiency of an engine and to reduce the quantity of NOx in the exhaust gas by a method wherein an auxiliary valve for opening a bleed port in a medium load zone is disposed in a vacuum pipe communicating with a negative pressure chamber within a negative pressure responsive EGR valve. CONSTITUTION:The EGR valve 1 arranged midway in an EGR passage for returning a part of the exhaust gas to an air intake system is controlled of its opening degree by the negative pressure of sucked air introduced into the negative pressure operating chamber 11 from an EGR port 3 which opens on the upstream side of a throttle valve 6 of a throttle body 2 through the vacuum pipe 4 and a negative pressure modulator 5. In this case, the auxiliary valve 20 is diposed midway in the vacuum pipe 4 between the EGR port 3 and the negative pressure modulator 5. The auxiliary valve 20 operates such as that in the medium load zone in the engine, the pressure in a second chamber 24 becomes substantially equal to the atmospheric pressure and the negative pressure of the sucked air is exerted on a first chamber 23 so that a valve body 21 is moved downward against the force of a spring 29 to thereby open the bleed port 30. |
