Sensor unit for combustible gases, especially suitable for future hydrogen economy, employs heated semiconductor sensor and temperature-sensitive heater

摘要

The semiconductor gas sensor (GS) is heated above ambient temperature. The temperature is measured using a temperature-sensitive heater. Simultaneously, signals from the sensor (GS) and signals from a thermal conductivity sensor (WS) are measured and sent to a common signal analysis unit for processing. The semiconductor gas sensor (GS) provides a selectivity- and zero point signal for the thermal conductivity sensor (WS). The analysis unit determines presence and/or concentration of gases from both of the signals. Once the semiconductor sensor signals detection of a given gas, the thermal conductivity sensor is brought into a state of greater sensitivity. When detection of the particular gas is confirmed, an alarm is given. Signals from the sensors (GS, WS) are weighted for processing. Either or both sensors are operated at two different temperatures, either in a low temperature, low power mode with reduced accuracy, or in a normal mode at higher temperature with greater accuracy. To prevent catalytic effects, the temperature at the thermal conductivity sensor is held below the temperature at which they set in, by a defined amount. Ambient temperature is measured. An independent claim is included for the corresponding sensor.