Sensor system

Abstract

A sensor system includes: a controller configured to: predict a temperature of exhaust gas of an internal combustion engine in a position in which an exhaust gas sensor having a sensor element is arranged; and control a heater so as to make a temperature of the sensor element close to a target temperature included in a predetermined range, wherein in cases where the predicted temperature of the exhaust gas is higher than a reference temperature, the controller is configured to make the target temperature lower when the predicted temperature is high than when it is low, within a range lower than the reference temperature, whereas in cases where the predicted temperature is lower than the reference temperature, the controller is configured to make the target temperature lower when the predicted temperature is high than when it is low, within a range higher than the reference temperature.

What is claimed is: 
     
         1 . A sensor system comprising:
 an exhaust gas sensor that is arranged in an exhaust passage of an internal combustion engine, and is provided with a sensor element and a heater configured to heat said sensor element; and   a controller configured to:
 predict a temperature of exhaust gas of said internal combustion engine in a position in which said exhaust gas sensor is arranged; and 
 control said heater so as to make a temperature of said sensor element close to a target temperature included in a predetermined range, wherein in cases where a prediction temperature, which is the temperature of the exhaust gas predicted by said controller, is higher than a reference temperature included in said predetermined range, said controller is configured to make said target temperature lower when said prediction temperature is high than when it is low, within a range lower than said reference temperature, whereas in cases where said prediction temperature is lower than said reference temperature, said controller is configured to make said target temperature lower when said prediction temperature is high than when it is low, within a range higher than said reference temperature. 
   
     
     
         2 . The sensor system as set forth in  claim 1 , wherein
 said controller is further configured to:
 predict, based on an operating state of said internal combustion engine, a flow rate of the exhaust gas of said internal combustion engine in a position in which said exhaust gas sensor is arranged; and 
 make an amount of deviation of said target temperature from said reference temperature larger when the flow rate of the exhaust gas predicted by said controller is large than when it is small. 
   
     
     
         3 . The sensor system as set forth in  claim 1 , further comprising:
 an accelerator opening sensor that detects an accelerator opening degree;   wherein said controller is further configured to predict said temperature of the exhaust gas based on the accelerator opening degree detected by said accelerator opening sensor.   
     
     
         4 . The sensor system as set forth in  claim 2 , further comprising:
 an accelerator opening sensor that detects an accelerator opening degree;   wherein said controller is further configured to predict said flow rate of the exhaust gas based on the accelerator opening degree detected by said accelerator opening sensor.   
     
     
         5 . The sensor system as set forth in  claim 1 , wherein
 said controller is further configured to provide an upper limit on a rate of change at the time of changing said target temperature.   
     
     
         6 . A sensor system comprising:
 an exhaust gas sensor that is arranged in an exhaust passage of an internal combustion engine, and is provided with a sensor element and a heater configured to heat said sensor element;   an accelerator opening sensor that detects an accelerator opening degree; and   a controller configured to control said heater so as to make a temperature of said sensor element close to a target temperature included in a predetermined range;   wherein in cases where said accelerator opening degree is such that the temperature of the exhaust gas in the surrounding of said exhaust gas sensor becomes higher than a reference temperature included in said predetermined range, said controller is configured to make said target temperature lower when said accelerator opening degree is large than when it is small, within a range lower than said reference temperature, whereas in cases where said accelerator opening degree is such that the temperature of the exhaust gas in the surrounding of said exhaust gas sensor becomes lower than said reference temperature, said controller is configured to make said target temperature lower when said accelerator opening degree is large than when it is small, within a range higher than said reference temperature.