Atmospheric pressure compensation system for exhaust gas recirculation

摘要

An atmospheric pressure compensation system for an exhaust gas recirculation (EGR) of an internal combustion engine comprises a vacuum source for generating vacuum of a substantially constant absolute value, an EGR valve for regulating the gas flow passing through an EGR passage by means of the vacuum, an atmospheric pressure compensation valve for opening and closing a passage for transmitting the vacuum from the vacuum source to the EGR valve, a control circuit for detecting the engine running conditions and generating a control signal, and an actuator for contributing to actuate the compensation valve in response to the control signal. The atmospheric pressure compensation valve comprises a valve body defining at least two chambers partitioned by a diaphragm. The atmospheric pressure is introduced into one of the chambers, while the substantially constant vacuum from the vacuum source is introduced into the other chamber. A servo valve is operatively connected to the diaphragm and to the actuator. The servo valve is subjected to a force of the actuator and the pressure difference between the atmospheric pressure and the substantially constant vacuum.