Patent ID: 9404892
Filing Date: 2016-08-02
CPC Classification: G01M,G01N

Claim Text:
1. A gas concentration sensor, comprising: a sound transmitter configured to emit a sound signal; a sound receiver configured to receive the sound signal emitted by the sound transmitter; a control device, which comprises a PLL circuit, configured to adjust a phase shift to a predefinable phase shift between the sound signal emitted by the sound transmitter and the sound signal received by the sound receiver; a phase comparator, with the PLL circuit configured to adjust a frequency of the emitted sound signal with respect to the received signal; and an evaluation unit configured to determine a change in a composition of a gas mixture based at least in part on a change in frequency of the sound signal relative to a frequency of a reference sound signal; and wherein the phase comparator compares the emitted sound signal and the received sound signal to determine whether the frequency of the emitted sound signal has to increase, decrease, or remain constant for the phase shift to correspond to the predefinable phase shift, wherein the evaluation unit is further configured to divide a maximum measuring range of the sensor into one of 3 regions and 5 regions, and output a signal that corresponds to a respective region as an indication of a change in the composition of the gas mixture.