Tyco Electronics Power Systems presents a CO2 gas sensor for forthcoming passenger-car air condi-tioning units that, instead of containing HFC-based R134a, utilize the alternative coolant R744 (carbon dioxide). The sensor is based on infrared spectral analysis and integrates various components, e.g. IR light sources, optical chamber thin-film interference filter, IR detector and electronics for processing measured values. The product's distinctive advantage is its patented operational principle from the firm GasBeetle GmbH, which guarantees very low energy consumption and maintenance-free, long-term op-eration due to its maximum demand of <200 mW.
Implemented in the vehicle, the fail-safe sensor not only warns reliably concerning CO2 leaks from R744 air conditioning units -- in temperature ranges from -40 to +85°C and relative humidity from 0 to 95% -- but it also concurrently and automatically controls interior ventilation and insures an optimal climate in the passenger compartment. Based on infrared spectral analysis, the CO2 gas sensor from Tyco Electronics recognizes gas-specific signatures in the 4.25 µm wavelength region. Because each gas possesses its own characteristic wavelength, the sensor functions precisely without cross-sensitivity to other gases. The thin-film interference filter in the sensor module ensures that the detector considers only the relevant part of the infrared spectrum, the one that is absorbed by the gas to be measured.
In addition, the Tyco Electronics CO2 gas sensor has a high level of operational reliability, as well as a very short response time of <11s. This is because, as opposed to a chemical gas sensor, the device re-quires no direct contact with the medium. The long-term operation is guaranteed via patented technology, which includes the integration of a sec-ond IR source, or reference source. The first IR source (measurement source) pulses in three-second intervals and thereby captures the CO2 concentration. The second source functions once within a 24-hour period in order to monitor the aging of the measurement source and adjust it if necessary.
