GAS SENSOR
A gas sensor ( 1 ) including: a sensor element ( 21 ) having a detection section ( 22 ) through an element introduction hole ( 25 ); a metallic shell ( 11 ); and a single-wall tubular protector ( 51 ) having a gas introduction hole ( 56 ) and a gas discharge hole ( 53 ); a gap G is present between the gas introduction hole and a forwardly facing surface ( 12 a ) of the metallic shell; when the gas introduction hole is viewed toward the rear end side, an area Sh of a portion of the forwardly facing surface seen through the gas introduction hole, is equal to or greater than ½ of an opening area Sg of the gas introduction hole; the element introduction hole is located on the forward end side in relation to a forwardmost end ( 12 f ) of the forwardly facing surface; and a distance L 1 of the gap G is smaller than a diameter D of the gas introduction hole.
1 . A gas sensor comprising:
a sensor element which extends in an axial direction and has a detection section formed in a forward end portion and detecting a gas to be detected through an element introduction hole;
a tubular metallic shell which surrounds a circumference of the sensor element in a radial direction and holds the sensor element; and
a single-wall tubular protector fixed to a circumference of a forward end portion of the metallic shell and surrounding the forward end portion of the sensor element, wherein
the protector has a gas introduction hole facing a rear end side and a gas discharge hole disposed on a forward end side in relation to the gas introduction hole;
a gap G in the axial direction is present between the gas introduction hole and a forwardly facing surface of the metallic shell;
when the gas introduction hole is viewed toward the rear end side in the axial direction, an area Sh of a portion of the forwardly facing surface of the metallic shell, which portion can be seen through the gas introduction hole, is equal to or greater than ½ of an opening area Sg of the gas introduction hole;
the entirety of the element introduction hole is located on the forward end side in relation to a forwardmost end of the forwardly facing surface of the metallic shell; and
a distance L 1 of the gap G is smaller than a diameter D of the gas introduction hole.
2 . A gas sensor comprising:
a sensor element which extends in an axial direction and has a detection section formed in a forward end portion and detecting a gas to be detected through an element introduction hole;
a tubular metallic shell which surrounds a circumference of the sensor element in a radial direction and holds the sensor element; and
a single-wall tubular protector fixed to a circumference of a forward end portion of the metallic shell and surrounding the forward end portion of the sensor element, wherein
the protector has a gas introduction hole facing a rear end side and a gas discharge hole disposed on a forward end side in relation to the gas introduction hole;
a gap G in the axial direction is present between the gas introduction hole and a forwardly facing surface of the metallic shell;
when the gas introduction hole is viewed toward the rear end side in the axial direction, an area Sh of a portion of the forwardly facing surface of the metallic shell, which portion can be seen through the gas introduction hole, is equal to or greater than ½ of an opening area Sg of the gas introduction hole;
the entirety of the element introduction hole is located on the forward end side in relation to a forwardmost end of the forwardly facing surface of the metallic shell; and
a distance L 1 of the gap G is smaller than a distance L 2 between the sensor element and the gas introduction hole in the radial direction.
3 . The gas sensor as claimed in claim 1 , wherein the forwardly facing surface of the metallic shell constitutes a horizontal surface parallel to the radial direction and/or a taper surface which tapers toward the forward end side and faces a radially outer side.
4 . The gas sensor as claimed in claim 1 , wherein, when the gas introduction hole is viewed from an outer side in the radial direction, the interior of the protector cannot be seen.
5 . The gas sensor as claimed in claim 2 , wherein the forwardly facing surface of the metallic shell constitutes a horizontal surface parallel to the radial direction and/or a taper surface which tapers toward the forward end side and faces a radially outer side.
6 . The gas sensor as claimed in claim 2 , wherein, when the gas introduction hole is viewed from an outer side in the radial direction, the interior of the protector cannot be seen.