| 摘要 |
PURPOSE:To efficiently decrease NOx and to thereby prevent a reduction in an output and an operational failure by providing a one-way valve and a two- way solenoid valve in parallel in a passage for introducing a port negative pressure in a throttle chamber into a diaphragm chamber of an EGR valve. CONSTITUTION:An exhaust port 4 communicates with an intake manifold 3 through an exhaust return passage 6 with an EGR valve 5. A negative pressure takeoff port 8 communicates with the diaphragm chamber 5a of the EGR valve 5. A check valve 10 and a two-way solenoid valve 11 are provided in parallel in a port negative pressure passage 9. The solenoid valve 11 is closed or opened in response to a signal from a control unit 15. Thus, a proper exhaust reflux is performed, enabling NOx to be efficiently decreased and the occurrence of problems, such as a reduction in an output and an operational failure, to be prevented. |
