Patent ID: 6415777
Filing Date: 2002-07-09
Classification: F02M

Abstract:
An internal combustion engine exhaust emission control system comprising:a flow path for conveying exhaust gas from an exhaust system of the engine to an intake system of the engine and comprising an orifice through which exhaust gas flow is constrained to pass, a valve for selectively restricting the flow path, a first port through which pressure in the flow path at a location upstream of the orifice is communicated to a first pressure reading port, and a second port through which pressure in the flow path at a location downstream of the orifice is communicated to a second pressure reading port, wherein the pressure communicated through the first port is communicated through a flow restrictor proximate the flow path that imposes a greater restriction on the communication of the flow path to the first pressure reading port than any restriction imposed on the communication of the flow path to the second pressure reading port.