| 摘要 |
An exhaust gas recirculation (EGR) system and construction is provided in which an EGR flow valve (36) and an air flow valve (34) are mounted on a common shaft (38) or, alternatively, interconnected by stepper motors or electric motors to ensure equal response times for the flow of EGR gases and air flow into the engine combustion chamber. In one embodiment, a secondary EGR valve (48) is provided in the EGR passage (32) to bleed the exhaust back-pressures to approximately atmospheric level to equal that of the air being inducted past a main air throttle valve. Finally, an EGR control system is provided for calculating the EGR flow rate as to be able to set the spark timing of the engine according to previously determined mapping data that provides values required for best fuel economy at any EGR rate. |
