| 摘要 |
Automobile engine exhaust gases are recycled through a recycling duct having a restricted upstream end opening into the exhaust system and first and second restricted downstream ends opening into the carburetor inlet induction conduit downstream and upstream respectively of the throttle valve. The restrictions for the recycling duct are dimensioned with respect to each other so that when the throttle valve is at its closed or idle position, a major quantity of the air required to support engine combustion at idle will bypass the throttle valve and flow through the portion of the recycling duct from the second downstream end to the first. The second restricted downstream end opens into the induction conduit at the usual fuel metering venturi restriction and is restricted appreciably less than the first downstream end, such that when the throttle valve is opened from the idle position, the first downstream end will have only a minor influence on the pressure in the recycling duct and the exhaust gas flow thereinto from the exhaust conduit via the restricted upstream end will be substantially a function of the pressure differential between the exhaust pressure at the upstream end and the venturi pressure at the second downstream end. The induction conduit pressure immediately upstream of the upstream leading edge of the blade of the throttle valve, when the latter is at its idle position, is employed to operate a valve to close the recycling duct completely at a location upstream of the two downstream ends during both idle and wide open throttle operation of the engine.
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