Sensor
Technology:
NOx OBD Application
The
NGK NOx sensor for reducing NOx tail pipe emission is a
stand alone component. This means no further calibration
is required. Easy system integration can be done by CAN
Bus.
It can also be used for On-Board Diagnosis (OBD).
- No
additional hardware in engine ECU required.
- Software-control
driven by microcontroller.
- Bidirectional
digital data transmission to/from engine ECU via CAN Bus.
The
NOx sensor provides three signals in parallel:
-
Binary
λ
-
Wide
range λ-signal
-
NOx
signal
Design
Concept of the sensor:
-
Binary
λ-signal: The binary λ-signal is obtained by
measuring voltage between reference and main pump electrode
(=Nernstian voltage),
-
Wide
range λ-signal: The exhaust gas penetrates into the
first cavity and the main pumping cell controls O2
concentration at low ppm levels. In this condition, NOx
will not be decomposed but all rich gases, such as HCs,
CO and H2 will be oxidised. The resulting pumping
current is proportional to the wide range λ-signal.
-
NOx
signal: The exhaust gas with less oxygen and without rich
gas will penetrate into the second chamber. In the second
chamber, Oxygen concentration is further reduced in order
to decompose NO into Oxygen and Nitrogen, using the catalytic
activity of a measuring electrode. This generated oxygen
is measured as the NOx signal.
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