Patent ID: 8918289
Filing Date: 2014-12-23
Classification: G01N

Abstract:
1. A combustible gas detection apparatus for measuring a combustible gas concentration of a gas under measurement, comprising: a combustible gas sensor having first and second heating resistors, each of which being placed in the gas under measurement and having a resistance that changes depending on the combustible gas concentration of the gas under measurement; and a control device having: an energization control section that alternately energizes the first and second heating resistors in such a manner as to adjust the resistance of each of the first and second heating resistors to a given value corresponding to a predetermined setting temperature; a first calculation section that calculates a first calculation value responsive to the combustible gas concentration of the gas under measurement based on a voltage across the first heating resistor during energization of the first heating resistor; a second calculation section that calculates a second calculation value responsive to the combustible gas concentration of the gas under measurement based on a voltage across the second heating resistor during energization of the second heating resistor; and an anomaly judgment section that judges the occurrence or non-occurrence of an anomaly in the first heating resistor by comparison of the first and second calculation values, wherein the anomaly judgment section is actuated every time a predetermined judgment condition is satisfied, wherein the control device has a normal-state operation section that, upon satisfaction of the predetermined judgment condition, causes the energization control section to allow the energization of the second heating resistor only for a time period required to measure the voltage across the second heating resistor for calculation of the second calculation value and to allow the energization of the first heating resistor at all times other than said time period, wherein the energization control section de-energizes the first heating resistor during the energization of the second heating resistor and de-energizes the second heating resistor during the energization of the first heating resistor, and wherein the control device has an abnormal-state operation section that, when the anomaly judgment section judges that the anomaly is occurring in the first heating resistor, controls the energization control section to stop the energization of the first and second heating resistors.