| 摘要 |
PURPOSE:To obtain the effective removal of the accumulated deposit in a diaphragm chamber by supplying the air by an air-introduction means into the diaphragm chamber for scavenging when a negative pressure regulation value to regulate the negative pressure for leading to an EGR control valve is continuously opened. CONSTITUTION:When a throttle valve 3 is opened to surpass the first negative pressure take-out port 16, a suction negative pressure is regulated in a negative pressure regulation valve 19, and introduced into a diaphragm chamber 14 of an EGR control valve 8 from a pipe 17 to open the valve 8 for exhaust gas returning. Meanwhile, when a throttle valve 3 is opened to surpass the second negative pressure take-out port 31, a diaphragm 20 of the negative pressure regulation valve 19 is moved upward against a spring 23, and a port 24 is closed by a valve element 25. Simultaneously, a negative pressure control valve 37 is opened, and an entrance port 34 of a nonreturn valve 33 is opened to the open air. Consequently, by the pulsation of exhaust gas, the open air is introduced into the first diaphragm chamber 21 for scavenging the same chamber 21. |
