Patent ID: 6308572
Filing Date: 2001-10-30
Classification: G01N

Abstract:
A gas concentration sensor comprising:a measurement chamber having an inflow path for allowing inflow of gas under measurement thereinto and an outflow path for allowing outflow of the gas therefrom;an ultrasonic element disposed on one of two wall surfaces located in opposition to each other within said measurement chamber, and capable of transmitting an ultrasonic wave toward the other of the two wall surfaces and receiving an ultrasonic wave reflected from the wall surface serving as a reflection surface; andgas concentration detection means for causing said ultrasonic element to transmit an ultrasonic wave and to receive the reflected wave, for measuring a propagation time between transmission of the ultrasonic wave and reception of the reflected wave, and for determining a concentration of a specific gas contained in the gas under measurement on the basis of the propagation time,said sensor being characterized in that said measurement chamber is formed such that a distance between an edge portion of the reflection surface and said ultrasonic element is greater than a distance between a central portion of the reflection surface and said ultrasonic element.