Gas sensor

A gas sensor configured to detect a concentration of a specific gas in a gas to be measured, the gas sensor comprising:

• a sensor element extending in an axial direction, the sensor element including a detector on a leading end side, and an element electrode on a rear end side;
• a tubular body including an opening end, the sensor element being disposed inside the tubular body;
• a terminal metal fitting extending in the axial direction;
• a lead wire being electrically connected to the element electrode via the terminal metal fitting, the lead wire extending outward from the opening end;
• an elastic body configured to seal the opening end, the lead wire being inserted into the elastic body;
• and
• a position fixing portion being in contact with a first end surface being an end surface of the elastic body on the leading end side in the axial direction, the position fixing portion configured to restrict the first end surface from moving toward the leading end side in the axial direction,
• wherein
• the tubular body includes a reduced diameter portion being formed on a rear end side of the tubular body, the reduced diameter portion configured to swage a part of the elastic body from a periphery,
• the tubular body in the reduced diameter portion has a diameter being constant in the axial direction,
• the elastic body has a post-swaging diameter Db being constant in the axial direction, the post-swaging diameter Db being a diameter of a swaged portion that is a portion of the elastic body being swaged by the reduced diameter portion, and
• the gas sensor satisfies Mathematical Expression (1) below:
• 0
• .
• 0
• ⁢
• 38
• ≤
• {
• (
• Lc
• ×
• Af
• )
• /
• (
• Ae
• ×
• Ld
• )
• }
• ×
• (
• 1
• -
• Db
• /
• Da
• )
• ≤
• 0
• .
• 1
• ⁢
• 71
• Mathematical
• ⁢
• Expression
• ⁢
• (
• 1
• )
• where,
• “Da” represents a pre-swaging diameter Da being a diameter of the elastic body before being swaged from the periphery by the reduced diameter portion,
• “Db” represents the post-swaging diameter Db,
• “Lc” represents a length Lc of the reduced diameter portion, the length Lc being a length of the reduced diameter portion in the axial direction,
• “Ld” represents a length Ld of a non-swaged portion, the length Ld being a length of the non-swaged portion of the elastic body, the non-swaged portion being on the leading end side with respect to the swaged portion in the axial direction,
• “Ae” represents a first area Ae being an area of the first end surface, and
• “Af” represents a second area Af being an area of a second end surface, the second end surface being in contact with the first end surface, the second end surface being an end surface of the position fixing portion on the rear end side in the axial direction.