Patent ID: 7603886

Claim:
A breath alcohol-measuring device comprising: a mouthpiece defining a gas flow path for receiving exhaled breathing air of a test subject; a flow diaphragm forming a throttle in said gas flow path; a first gas line connected up stream of said flow diaphragm and in fluid connection with gas in said flow path; a first pressure sensor connected via said first gas line for detecting gas pressure in said gas flow path of said mouthpiece, upstream of said flow diaphragm; a second gas line; a sampling system comprising a bellows, in fluid connection with said second gas line, and with a piezo drive acting on said bellows to compress said bellows and to expand said bellows to draw gas into said bellows from said second gas line; an inlet channel connected to said mouthpiece downstream of said flow diaphragm and in fluid connection with gas in said flow path; an alcohol sensor connected to said mouthpiece via said inlet channel and connected to said sampling system via said second gas line for receiving a breathing gas sample from the received exhaled breathing air upon an expanding of said bellows by said piezo drive; a second gas line throttle providing a pressure drop in said second gas line between said alcohol sensor and said sampling system; a second pressure sensor connected to said second gas line between said second gas line throttle and said bellows; and an evaluating and control unit receiving measured signals of said first pressure sensor and said second pressure sensor and of said alcohol sensor and actuating said sampling system depending on a pressure signal of said second pressure sensor, with said pressure signal of said second pressure sensor being proportional to a gas volume drawn through said alcohol sensor.