BeamQ 760nm DFB Laser Sensor for O2 Sensing TO Package
The Oxigraf sensor uses laser diode absorption technology to measure oxygen concentration in the gas sample. A laser diode produces light in the visible spectrum at 760 nanometers, which is absorbed by oxygen. To analyze oxygen the laser beam is focused through the sample gas onto a detector.
Three types of oxygen sensors, i.e., concentration cell (zirconia sensors), oxide semiconductor (TiO2 sensors) and electrochemical pumping oxygen sensors (limiting current sensors) are now available for control of the air—fuel ratio of engines.
What are the two types of O2 sensors?
Modern oxygen sensors are much faster and more accurate than their older counterparts. This allows the engine to enter closed loop control faster which decreases emissions and fuel usage by as much as 15-20%. O2 sensors are separated into two main types, narrow band and wideband.
Narrow band oxygen sensors react with the oxygen molecules in the exhaust. If the gas mixture is rich, the oxygen content will be low, and the sensor will send a rich signal to the ECU. This will decrease the amount of fuel added to the cylinder. If the gas is lean, the oxygen content is higher, and the sensor will send a lean signal.
Wideband sensors are the newest technology. These sensors have an additional chamber called the pump cell that accurately measures the oxygen concentration on a complete lambda scale. Electronic circuitry must be used to maintain voltage supplies to maintain a consistent cell temperature and stoichiometric balance inside the measurement chamber. The balance is maintained by the pump cell which ‘pumps’ oxygen ions in and out of the measurement chamber. The control circuit measures how hard the pump cell is working and determines the air fuel ratio.
Most vehicles have two oxygen sensors installed in the exhaust system; at least one in front of the catalytic converter (upstream) and one after the converter (downstream). The purpose of the upstream sensor is to manage the closed loop performance of the engine. The downstream sensor is used to monitor the condition of the catalytic converter.
The typical life expectancy of an oxygen sensor is 30,000 to 50,000 miles. However, when constantly exposed to the harsh environment found in an automobile’s exhaust system, the oxygen sensor sustains a constant barrage of harmful exhaust gases, extreme heat, and high velocity particulates.