Gas sensor

Abstract

A gas sensor includes a solid electrolyte layer with oxygen ion conductivity, a gas flow portion (ranging from a gas inlet port to a second inner cavity), a particular gas detector (including a main pump cell, a measurement pump cell, an auxiliary pump cell, etc.), and a control device. Prior to startup of the gas sensor, the control device sets electric power supplied to a heater such that a temperature difference between a temperature of the heater and a preset target temperature becomes zero, and determines, on the basis of the set electric power, whether temperature raising control of supplying the set electric power to the heater is to be executed.

What is claimed is: 
     
         1 . A gas sensor comprising:
 a solid electrolyte layer with oxygen ion conductivity;   a resistance heating element embedded in the solid electrolyte layer;   a gas flow portion provided inside the solid electrolyte layer;   a particular gas detector detecting particular gas in measurement object gas introduced to the gas flow portion; and   a controller setting, prior to startup of the gas sensor, electric power supplied to the resistance heating element such that a temperature of the resistance heating element becomes equal to a preset target temperature, and determining, on basis of the set electric power, whether temperature raising control of supplying the set electric power to the resistance heating element is to be executed.   
     
     
         2 . The gas sensor according to  claim 1 , wherein the controller determines whether the set electric power exceeds a threshold corresponding to a water spraying amount at which cracking occurs in the gas sensor, and executes the temperature raising control if a result of the determination as for whether the set electric power exceeds the threshold is NO. 
     
     
         3 . The gas sensor according to  claim 2 , wherein the controller supplies the electric power to the resistance heating element within a range not exceeding the threshold if the result of the determination as for whether the set electric power exceeds the threshold is YES. 
     
     
         4 . The gas sensor according to  claim 3 , wherein, at predetermined timing after starting the supply of the electric power to the resistance heating element within the range not exceeding the threshold, the controller sets again the electric power supplied to the resistance heating element such that the temperature of the resistance heating element becomes equal to the target temperature, and determines, on basis of the set electric power, whether the temperature raising control of supplying the set electric power to the resistance heating element is to be executed. 
     
     
         5 . The gas sensor according to  claim 1 , further comprising a porous protective film covering at least portions of the solid electrolyte layer, the portions corresponding to an externally-exposed electrode of the particular gas detector and an inlet of the gas flow portion. 
     
     
         6 . The gas sensor according to  claim 2 , further comprising a porous protective film covering at least portions of the solid electrolyte layer, the portions corresponding to an externally-exposed electrode of the particular gas detector and an inlet of the gas flow portion. 
     
     
         7 . The gas sensor according to  claim 3 , further comprising a porous protective film covering at least portions of the solid electrolyte layer, the portions corresponding to an externally-exposed electrode of the particular gas detector and an inlet of the gas flow portion. 
     
     
         8 . The gas sensor according to  claim 4 , further comprising a porous protective film covering at least portions of the solid electrolyte layer, the portions corresponding to an externally-exposed electrode of the particular gas detector and an inlet of the gas flow portion.