Zirconia sensor Oxygen sensor

a planar zirconia sensor (schematic picture)

the zirconium dioxide, or zirconia, lambda sensor based on solid-state electrochemical fuel cell called nernst cell. 2 electrodes provide output voltage corresponding quantity of oxygen in exhaust relative in atmosphere.

an output voltage of 0.2 v (200 mv) dc represents lean mixture of fuel , oxygen, amount of oxygen entering cylinder sufficient oxidize carbon monoxide (co), produced in burning air , fuel, carbon dioxide (co2). output voltage of 0.8 v (800 mv) dc represents rich mixture , 1 high in unburned fuel , low in remaining oxygen. ideal setpoint approximately 0.45 v (450 mv) dc. quantities of air , fuel in optimum ratio, ~0.5% lean of stoichiometric point, such exhaust output contains minimal carbon monoxide.

the voltage produced sensor nonlinear respect oxygen concentration. sensor sensitive near stoichiometric point (where λ = 1) , less sensitive when either lean or rich.

the ecu control system uses feedback sensor adjust fuel/air mixture. in control systems, time constant of sensor important; ability of ecu control fuel-air-ratio depends upon response time of sensor. aging or fouled sensor tends have slower response time, can degrade system performance. shorter time period, higher so-called cross count , more responsive system.

the sensor has rugged stainless steel construction internally , externally. due sensor has high resistance corrosion allowing used in aggressive environments high temperature/pressure.

the zirconia sensor of narrow band type, referring narrow range of fuel/air ratios responds.