Exhaust gas recirculation system for internal combustion engine

摘要

The system includes a spring-loaded (20) EGR (exhaust gas recirculation) valve, (11) with a vacuum actuating chamber (21). The spring urges the valve body (17) toward its seat (15). There is a BPT (back-pressure measuring) valve (31) in parallel with the EGR valve. The EGR channel (4) leading from the exhaust pipe to the two valves has a fixed throttle (5) in it. The common duct (23) leading from the two valves passes to a third, solenoid valve (25) which can connect the valve either upstream or downstream of the throttle valve (6) controlling the engine. The third valve is connected to a control circuit (7) which receives inputs from a temperature sensor, a crankshaft angle sensor, a spark sensor, and a mixture strength sensor (81-84). Independent claims are included for a diagnostic device and a diagnostic method for the EGR system.