Gas sensor

A gas sensor comprising:

• a plate-like detection element extending in a direction of an axis, having a detection portion in a front end region thereof for detecting a particular gas component contained in gas to be measured, and having a heater laminated thereon for heating the detection portion;
• a tubular metallic shell surrounding the detection element from radially outside of the detection element while allowing the detection portion to project from a front end thereof;
• and
• a protector accommodating therein the detection portion of the detection element and fixed to the metallic shell;
• the gas sensor being disposed in an intake passage of an internal combustion engine;
• the gas sensor being characterized in that:
• the protector has an inner protector disposed with a gap existing between the detection portion and the inner protector, and an outer protector disposed with a gap existing between the inner protector and the outer protector;
• the inner protector has an inner wall portion disposed radially outward of the detection portion and having an inner gas inlet for introducing the gas to be measured into the interior of the inner protector;
• the outer protector has an outer wall portion disposed radially outward of the inner wall portion and having an outer gas inlet for introducing the gas to be measured into the interior of the outer protector;
• a clearance of 1.35 mm or less is provided between the detection portion and at least a portion of the inner wall portion;
• when the gas sensor is in use, the inner protector is higher in temperature than the outer protector;
• and
• the outer wall portion and the inner wall portion form a clearance of 1 mm or greater therebetween as measured over the entire region of the outer wall portion.