Gas measurement device and measurement method thereof

Patent metadata

Field	Value
Publication number	US-2016003757-A1
Application number	US-201514726823-A
Country	US
Kind code	A1
Filing date	Jun 1, 2015
Priority date	Jul 2, 2014
Publication date	Jan 7, 2016
Grant date	—

Abstract

A gas measurement device measures gas using a gas sensor including a sense resistance exposed to the gas and a reference resistance not exposed to the gas. The gas measurement device applies a first current value and a second current value to the sensor. A detector functions to detect a first resistance variation and a second resistance variation of the sense resistance exposed to the gas with respect to the reference resistance as a function of the first current value and the second current value, respectively. The resistance variation dependent on relative humidity is then determined as a function of the first and second resistance variations and a first constant. The resistance variation dependent on gas content is then determined as a function of the first and second resistance variations and a second (different) constant.

First claim

1 . A gas measurement device for measuring gas using a gas sensor comprising at least one resistance exposed to at least one gas and at least one reference resistance not exposed to the gas, said gas measurement device comprising:
a managing device configured to manage the gas sensor so that the gas sensor receives at least a first current value Il and a second current value Ih, a detector configured to detect a first resistance variation ΔR(Il) and a second resistance variation ΔR(Ih) of the resistance exposed to the gas with respect to the reference resistance as a function of the first current value Il and the second current value Ih respectively, and a calculation circuit configured to calculate: a resistance variation dependent on relative humidity and a resistance variation dependent on gas concentration as a function of first resistance variation ΔR(Il) and the second resistance variation ΔR(Ih).

2 . The gas measurement device according to claim 1 , wherein the calculation circuit is configured to:
calculate the resistance variation dependent on relative humidity as a function of a difference between the first ΔR(Il) resistance variation multiplied by a first constant K 1 and the second ΔR(Ih) resistance variation; and calculate the resistance variation dependent on gas concentration as a function of a difference between the first ΔR(Il) resistance variation multiplied by a second constant K 2 and the second resistance variation ΔR(Ih), wherein the first constant and the second constant have different values.

3 . The gas measurement device according to claim 1 , wherein the calculation of the resistance variation dependent relative humidity utilizes the following equation K 1 ×ΔR(Il)−ΔR(Ih) and the calculation of the resistance variation dependent on gas concentration utilizes the following equation K 2 ×ΔR(Il)−ΔR(Ih), wherein K 1 and K 2 are first and second, different, constants.

4 . The gas measurement device according to claim 3 , wherein the values of the first and second constants are 1.827 and 2.165.

5 . A measurement apparatus, comprising:
a gas measurement device comprising:
a managing device configured to manage the gas sensor so that the gas sensor receives at least a first current value Il and a second current value Ih,
a detector configured to detecting a first resistance variation ΔR(Il) and a second resistance variation ΔR(Ih) of the resistance exposed to the gas with respect to the reference resistance as a function of the first current value Il and the second current value Ih respectively,
a calculation circuit configured to calculate: a resistance variation dependent on relative humidity and a resistance variation dependent on gas concentration as a function of first resistance variation ΔR(Il) and the second resistance variation ΔR(Ih); and
a gas sensor comprising at least one resistance exposed to the gas and at least one reference resistance not exposed to the gas.

6 . The measurement apparatus according to claim 5 , wherein the calculation circuit is configured to:
calculate the resistance variation dependent on relative humidity as a function of a difference between the first ΔR(Il) resistance variation multiplied by a first constant K 1 and the second ΔR(Ih) resistance variation; and calculate the resistance variation dependent on gas concentration as a function of a difference between the first ΔR(Il) resistance variation multiplied by a second constant K 2 and the second resistance variation ΔR(Ih), wherein the first constant and the second constant have different values.

7 . The measurement apparatus according to claim 6 , wherein said gas sensor is a Wheatstone bridge.

8 . A method for measuring gas by means of a gas sensor comprising at least one resistance exposed to at least one gas and at least one reference resistance not exposed to the gas, said method comprising:
sending a first current value Il to the gas sensor, detecting the first resistance variation ΔR(Il) of the resistance R 2 exposed to the gas with respect to the reference resistance R 1 , sending a second current value Ih to the gas sensor, detecting the second resistance variation ΔR(Ih) of the resistance R 2 exposed to the gas with respect to the reference resistance R 1 , and calculating a resistance variation dependent on relative humidity and calculating a resistance variation dependent on gas concentration as a function of the first resistance variation ΔR(Il) and the second resistance variation ΔR(Ih).

9 . The method according to claim 8 , wherein:
calculating the resistance variation dependent on relative humidity comprises calculating a difference between the first ΔR(Il) resistance variation multiplied by a first constant K 1 and the second ΔR(Ih) resistance variation; and calculating the resistance variation dependent on gas concentration comprises calculating a difference between the first ΔR(Il) resistance variation multiplied by a second constant K 2 and the second resistance variation ΔR(Ih), wherein the first constant and the second constant have different values.

10 . The method according to claim 9 , wherein the calculation of the resistance variation dependent relative humidity utilizes the following equation K 1 ×ΔR(Il)−ΔR(Ih) and the calculation of the resistance variation dependent on gas concentration utilizes the following equation K 2 ×ΔR(Il)−ΔR(Ih), wherein K 1 and K 2 are first and second, different, constants.

11 . The method according to claim 10 , wherein the values of the first and second constants are 1.827 and 2.165.

Assignees

• St Microelectronics Srl

Inventors

• Biancolillo Pasquale
• Recchia Angelo
• Franco Pasquale
• Cicero Antonio
• Bruno Giuseppe

Classifications

• G01N27/18 Primary

  caused by changes in the thermal conductivity of a surrounding material to be tested (G01N27/20 takes precedence) · CPC title

• G01N27/121 Primary

  for determining moisture content, e.g. humidity, of the fluid (moisture content of the tested material G01N27/048) · CPC title