Gas concentration sensor drift and failure detection system

The present disclosure relates generally to a detection system and, more particularly, to a system for detecting when a gas concentration sensor has drifted or failed.

Combustion engines, including diesel engines, gasoline engines, natural gas engines, and other engines known in the art, may exhaust a complex mixture of air pollutants. The air pollutants may be composed of gaseous and solid compounds, including particulate matter, nitrogen oxides (NO_x), and sulfur compounds. Due to heightened environmental concerns, exhaust emission standards have become increasingly stringent. To comply with these emission standards, engine manufacturers employ gas concentration sensors. But, gas concentration sensors are wear-out devices that eventually fail and require replacement (i.e. gas concentration sensors eventually become faulty). Furthermore, gas concentration sensors drift over time (i.e. measurements become miscalibrated). Miscalibrated measurements may result in noncompliance with the emission standards. Therefore, gas concentration sensors must be recalibrated periodically. Replacing and recalibrating gas concentration sensors is costly in both labor and parts, and this problem can be exacerbated when the engine is remotely located. Specifically, because reliable testing and calibration equipment may be unavailable, gas concentration sensors may be needlessly replaced.

One way to minimize the affect of a faulty gas concentration sensor is described in U.S. Patent Application Publication No. 2004/0221641 (the \'641 publication) by Moritsugu et al., published on Nov. 11, 2004. The \'641 publication describes a fault detecting apparatus for a gas concentration sensor. The fault detecting apparatus includes a storage device and a fault detecting circuit. The storage device stores conditions in which certain fault types may be detected. When one of these conditions is detected, the fault detecting circuit initiates detection of the corresponding fault type. Specifically, the fault detecting circuit determines whether there is a fault based on an output of the gas concentration sensor. If there is a fault, the fault detecting apparatus turns on a malfunction indicator lamp. Additionally, if the fault is minor, the fault detecting apparatus adjusts the functioning of the gas concentration sensor. But, if the fault is major, the fault detecting apparatus discontinues use of the gas concentration sensor.

Although the fault detecting apparatus of the \'641 publication may improve detection of a faulty gas concentration sensor, it may do little to improve detection of a miscalibrated gas concentration sensor. Furthermore, though the fault detecting apparatus of the \'641 publication may turn on a malfunction indicator lamp, it may do little to reduce the economic impact of the gas concentration sensor\'s failure. In particular, the operator may need to discontinue use of an affected engine until the gas concentration sensor can be replaced. In addition, the fault detecting apparatus of the \'641 publication may increase the complexity and cost of the gas concentration sensor, but it may do little to prolong the life of the gas concentration sensor.

The disclosed system and method are directed to overcoming one or more of the problems set forth above.

In one aspect, the present disclosure is directed to a drift and failure detection system for a gas concentration sensor. The system includes a first gas concentration sensor configured to detect a first gas concentration and generate a corresponding first signal. The system also includes a second gas concentration sensor configured to detect a second gas concentration and generate a corresponding second signal. In addition, the system includes 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.

In another aspect, the present disclosure is directed to a method of detecting when a gas concentration sensor has drifted or failed. The method includes detecting a first gas concentration with a first gas concentration sensor. Additionally, the method includes detecting a second gas concentration with a second gas concentration sensor. The method also includes calculating a difference between the detected first and second gas concentrations. In addition, the method includes providing an out-of-tolerance gas concentration sensor warning based on the calculated difference between the detected first and second gas concentrations.

FIG. 1 illustrates a combustion engine 10, which may be utilized by various types of machines such as, for example, fixed or mobile machines that perform some type of operation associated with an industry such as mining, construction, farming, transportation, power generation, tree harvesting, forestry, or another industry known in the art. Combustion engine 10 may be an internal combustion engine, such as, for example, a diesel engine, a gasoline engine, or a natural gas engine. Combustion engine 10 may alternatively be another power source such as a furnace.