Eaton Corporation

Lawrence E Egle

Andrew A Kenny

Daniel C Stahly

Robert G Sokalski

A closed loop system for controlling exhaust gas recirculation (EGR) in an automotive engine. An electrical program command signal from an on-board engine computer/controller actuator through a motor driven circuit, a stepper motor to turn an axial lead screw having a follower thereon connected to a rod for moving the valve poppet to control flow. An orifice plate with differential flow pressure taps is disposed in the EGR passage downstream of a flow control valve poppet. The differential pressure from the taps is sensed by a pressure responsive diaphragm. A stationary proximity sensor using an eddy current principle detects changes in position of the diaphragm and in response thereto generates an electrical feedback signal proportional to EGR flow through the orifice which compared with the command signal to generate a control signal for controlling the stepper motor.

Exhaust gas recirculation control system

A vacuum operated EGR valve/controller having a vacuum signal responsive diaphragm converted to operate the EGR poppet valve. A flow limiting orifice is provided upstream of the valve and a flow sensing pressure tap provided intermediate the valve and the orifice. Flow pressure is sensed by a piezoresistive transducer which gives an electrical signal indicative thereof. In one embodiment, the transducer is stationary and flow sensing tube is extended to the valve body. In a second embodiment, the transducer is mounted on the diaphragm for movement therewith and flow sensing is internal through the valve actuator. In another embodiment, a flow sensing orifice is provided downstream of the valve and the transducers has a reference and dynamic probe for sensing the differential of flow pressure on opposite sides of the sensing orifice. In another embodiment, plates attached to the diaphragm form a flow pressure sensing chamber and the transducer tube is received through the plate rail and is sealed by a flexible seal.

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Itasca, IL, United States of America

Lawrence E Egle