Exhaust Gas Processing System Independent to Engine Controls

摘要

A multi-functional apparatus and method for diagnosing issues in an engine system with a SCR exhaust gas processing system and controlling reductant delivery to the SCR system. The apparatus includes a Venturi exhaust passage device with a reductant injector positioned on a transition from a low pressure passage to a downstream high pressure passage. Temperature and pressures in the Venturi exhaust passage device are measured, and an exhaust flow rate value is calculated. The exhaust flow rate value can be used in controlling reductant delivery, and with a downstream lambda sensing value, the exhaust flow rate value, and a temperature sensing value, a variety of issues in the engine system and the SCR system can be detected. No engine operating parameter is required in the SCR controls and diagnostic algorithms, and less reductant deposit is introduced due to the elimination of stagnant area in the exhaust passage device.

主权项

1. An exhaust gas processing system of an internal combustion engine, comprising:
a selective catalytic reduction device for reducing NOx in an exhaust gas flow produced by said internal combustion engine; a decomposition pipe positioned upstream from said selective catalytic reduction device including a first high pressure passage, a low pressure passage, and a second high pressure passage, wherein said first high pressure passage has a cross-section area larger than that of said low pressure passage; a temperature sensor providing a temperature sensing signal indicative of a temperature in said first high pressure passage; a first pressure sensor generating a pressure sensing signal indicative of a pressure in said first high pressure passage; a second pressure sensor generating a differential pressure sensing signal indicative of a difference between said pressure in said first high pressure passage and a pressure in said low pressure passage; a reductant injection device positioned at a transition between said low pressure passage and said second high pressure passage for providing a reductant reducing NOx in said exhaust gas flow; and a controller configured to provide a control signal to said reductant injection device controlling a delivery rate of said reductant into said exhaust gas flow in response to said temperature sensing signal, said pressure sensing signal, and said differential pressure sensing signal.