Gas concentration sensor drift and failure detection system

Abstract

A system for detecting when a gas concentration sensor has drifted or failed is disclosed. The system has a first gas concentration sensor configured to detect a first gas concentration and generate a corresponding first signal. The system also has a second gas concentration sensor configured to detect a second gas concentration and generate a corresponding second signal. In addition, the system has a controller in communication with the first and second gas concentration sensors. Based on the first and second signals, the controller is configured to provide an out-of-tolerance gas concentration sensor warning.

1 . A drift and failure detection system for a gas concentration sensor, comprising:
 a first gas concentration sensor configured to detect a first gas concentration and generate a corresponding first signal;   a second gas concentration sensor configured to detect a second gas concentration and generate a corresponding second signal; and   a controller in communication with the first and second gas concentration sensors, and configured to provide an out-of-tolerance gas concentration sensor warning based on the first and second signals.   
   
   
       2 . The drift and failure detection system of  claim 1 , further including an exhaust system, wherein the first and second gas concentration sensors are located within the exhaust system. 
   
   
       3 . The drift and failure detection system of  claim 2 , wherein the exhaust system includes a first bypass, and the second gas concentration sensor is located within the first bypass. 
   
   
       4 . The drift and failure detection system of  claim 3 , wherein:
 the controller includes a clock configured to measure time and generate a corresponding time signal;   the first bypass includes at least one valve to adjust a flow; and   the controller is in further communication with the at least one valve and configured to control the at least one valve based upon at least one of the first, second, and clock signals.   
   
   
       5 . The drift and failure detection system of  claim 4 , wherein the flow is an exhaust flow. 
   
   
       6 . The drift and failure detection system of  claim 3 , wherein the exhaust system includes a second bypass, and the first gas concentration sensor is located within the second bypass. 
   
   
       7 . The drift and failure detection system of  claim 1 , further including an air/fuel supply system, wherein the controller is in further communication with the air/fuel supply system and configured to adjust an air/fuel ratio based on at least one of the first and second signals. 
   
   
       8 . The drift and failure detection system of  claim 1 , further including a warning device, wherein the controller is in further communication with the warning device and configured to activate the warning device based on the first and second signals. 
   
   
       9 . A method of detecting when a gas concentration sensor has drifted or failed, comprising:
 detecting a first gas concentration with a first gas concentration sensor;   detecting a second gas concentration with a second gas concentration sensor;   calculating a difference between the detected first and second gas concentrations; and   providing an out-of-tolerance gas concentration sensor warning based on the calculated difference between the detected first and second gas concentrations.   
   
   
       10 . The method of  claim 9 , further including measuring a time. 
   
   
       11 . The method of  claim 10 , further including adjusting a flow based on the measured time. 
   
   
       12 . The method of  claim 11 , wherein the flow is an exhaust flow. 
   
   
       13 . The method of  claim 9 , wherein calculating the difference between the detected first and second gas concentrations includes:
 calculating an average detected first gas concentration;   calculating an average detected second gas concentration; and   comparing the average detected first gas concentration and the average detected second gas concentration.   
   
   
       14 . The method of  claim 9 , further including adjusting an air/fuel ratio based on at least one of the detected first and second gas concentrations. 
   
   
       15 . The method of  claim 9 , further including activating a warning device based on the calculated difference between the detected first and second gas concentrations. 
   
   
       16 . A combustion engine, comprising:
 an air/fuel supply system;   a combustion chamber located downstream of the air/fuel supply system;   an exhaust system located downstream of the combustion chamber, the exhaust system including:
 a first gas concentration sensor configured to detect a first gas concentration and generate a corresponding first signal; and 
 a second gas concentration sensor configured to detect a second gas concentration and generate a corresponding second signal; and 
   an engine control module in communication with the first and second gas concentration sensors, and the air/fuel supply system, and configured to:
 provide an out-of-tolerance gas concentration sensor warning based on the first and second signals; and 
 adjust an air/fuel ratio based on at least one of the first and second signals. 
   
   
   
       17 . The combustion engine of  claim 16 , wherein the exhaust system further includes a first bypass, and the second gas concentration sensor is located within the first bypass. 
   
   
       18 . The combustion engine of  claim 17 , wherein:
 the engine control module includes a clock configured to measure time and generate a corresponding time signal;   the first bypass includes at least one valve to adjust a flow; and   the engine control module is in further communication with the at least one valve and configured to control the at least one valve based on at least one of the first, second, and clock signals.   
   
   
       19 . The combustion engine of  claim 17 , wherein the exhaust system further includes a second bypass, and the first gas concentration sensor is located within the second bypass. 
   
   
       20 . The combustion engine of  claim 16 , wherein:
 the first gas concentration sensor is a NO x  concentration sensor; and   the second gas concentration sensor is a NO x  concentration sensor.