Sensor configuration for caustic environments

Abstract

Methods and apparatuses for using a sensor. A sensor is selectively coupled with an environmental condition for which the sensor is designed when a first predetermined event occurs. The sensor is selectively decoupled from the environmental condition when a second predetermined event occurs.

1 . A method for using a sensor, comprising: 
 selectively coupling a NOx sensor with a diesel engine exhaust flow when a first predetermined event occurs; and    selectively decoupling the sensor from the flow when a second predetermined event occurs.    
     
     
         2 . The method of  claim 1  wherein selectively coupling comprises at least one of: 
 directing the flow in proximity to the sensor so that the sensor is operable to monitor NOx in the flow; and  
 directing the sensor into proximity with the flow so that the sensor is operable to monitor NOx in the flow.  
 
     
     
         3 . The method of  claim 1  wherein the first predetermined event comprises a passage of a first predetermined amount of time.  
     
     
         4 . The method of  claim 1  wherein the second predetermined event comprises a passage of a second predetermined amount of time.  
     
     
         5 . The method of  claim 1  further comprising: 
 cleansing the area in the proximity of the sensor when the sensor is decoupled from the flow.  
 
     
     
         6 . An apparatus for sensing a condition, comprising: 
 a first exhaust flow path operable to transmit an exhaust flow from a diesel engine;    a second exhaust flow path operable to transmit an exhaust flow from the engine;    a control valve coupled with the first exhaust flow path and the second exhaust flow path, the control valve operable to receive an exhaust flow from the engine and to selectively transmit the exhaust flow from the engine to one of the first and second exhaust flow paths as a function of a control signal;    a NOx sensor coupled with the second exhaust flow path, the sensor operable to monitor the NOx in the exhaust flow in the second exhaust flow path and to transmit a first signal as a function thereof.    
     
     
         7 . The apparatus of  claim 6  wherein the control valve is further operable to isolate the second exhaust flow path from the exhaust flow of the engine as a function of the control signal.  
     
     
         8 . The apparatus of  claim 6  further comprising a flush valve coupled with the second exhaust flow path, the flush valve operable to transmit a first fluid to the second exhaust flow path as a function of a second control signal.  
     
     
         9 . The apparatus of  claim 8  wherein the first fluid comprises air.  
     
     
         10 . The apparatus of  claim 8  wherein the flush valve is integrated with the control valve.  
     
     
         11 . A apparatus for sensing a condition, comprising: 
 a first exhaust flow path operable to transmit an exhaust flow from a diesel engine;    a NOx sensor operable to monitor the NOx in the exhaust flow in proximity to the sensor and to transmit a first signal as a function thereof; and    a first actuator operable to selectively couple and isolate the sensor from the first exhaust flow path as a function of a control signal.    
     
     
         12 . The apparatus of  claim 11  wherein the first actuator is operable to insert the first sensor into the first exhaust flow path as a function of the control signal.