Air-fuel ratio sensor

An air-fuel ratio sensor, comprising:

• a cylindrical housing having a first end and an opposite second end;
• an air-fuel ratio sensor element inserted through the cylindrical housing and capable of detecting an air-fuel ratio in an atmosphere of unburnt gas, the sensor element having a detecting portion for performing detection of the air-fuel ratio;
• an atmospheric side cover disposed on the first end of the cylindrical housing and defining an inside chamber for storing therein atmospheric air;
• and
• a measured gas side cover disposed on the second end of the cylindrical housing so as to cover the air-fuel ratio sensor element and defining an inside chamber for storing therein a gas to be measured,
• wherein the measured gas side cover has a nested structure composed of a plurality of cup-shaped cover members disposed one inside another, each of the cup-shaped cover members having a gas inlet hole formed in a side wall thereof for introducing the measured gas into the inside chamber of the measured gas side cover, and a bottom hole formed in a bottom wall thereof,
• wherein the gas inlet hole of an innermost one of the plurality of cover members that directly faces the air-fuel ratio sensor element is offset from the detecting portion of the air-fuel ratio sensor element toward the housing in an axial direction of the air-fuel ratio sensor,
• wherein the cylindrical housing has an end face facing the inside chamber of the measured gas side cover at the second end of the housing, the detecting portion of the air-fuel ratio sensor element is spaced from the end face of the housing by a first distance in the axial direction of the sensor, and the gas inlet hole of the innermost cover member has a center located at a position spaced from the end face of the housing in the axial direction of the sensor by a second distance smaller than one-half of the first distance, and
• wherein the sensor is disposed in a surge tank for performing measurement of an air-fuel ratio in an evaporated gas.

An air-fuel ratio sensor comprising:

• a cylindrical housing having a first end and an opposite second end;
• an air-fuel ratio sensor element inserted through the cylindrical housing and capable of detecting an air-fuel ratio in an atmosphere of unburnt gas, the sensor element having a detecting portion for performing detection of the air-fuel ratio;
• an atmospheric side cover disposed on the first end of the cylindrical housing and defining an inside chamber for storing therein atmospheric air;
• and
• a measured gas side cover disposed on the second end of the cylindrical housing so as to cover the air-fuel ratio sensor element and defining an inside chamber for storing therein a gas to be measured, wherein the measured gas side cover has a nested structure composed of a plurality of cup-shaped cover members disposed one inside another, each of the cup-shaped cover members having a gas inlet hole formed in a side wall thereof for introducing the measured gas into the inside chamber of the measured gas side cover, and a bottom hole formed in a bottom wall thereof, and wherein the gas inlet hole of an innermost one of the plurality of cover members that directly faces the air-fuel ratio sensor element is offset from the detecting portion of the air-fuel ratio sensor element toward the housing in an axial direction of the air-fuel ratio sensor, and
• a partition structure for blocking flow communication of the measured gas between the gas inlet hole of each cover member and the bottom hole of each cover member,
• wherein the plurality of cover members of the measured gas side cover include an inner cover member forming the innermost cover member, an outer cover member disposed outside the inner cover member with a bottom wall thereof held in close contact with a bottom wall of the inner cover member, and an explosionproof cover disposed outside the outer cover member with a bottom wall thereof separated from the bottom wall of the outer cover member, the partition structure includes the bottom walls of the inner and outer cover members held in close contact with each other, and a partition plate hermetically fitted in the explosionproof cover member and adjacent to the bottom wall of the explosionproof cover member.

An air-fuel ratio sensor comprising:

• a cylindrical housing having a first end and an opposite second end;
• an air-fuel ratio sensor element inserted through the cylindrical housing and capable of detecting an air-fuel ratio in an atmosphere of unburnt gas, the sensor element having a detecting portion for performing detection of the air-fuel ratio;
• an atmospheric side cover disposed on the first end of the cylindrical housing and defining an inside chamber for storing therein atmospheric air;
• and
• a measured gas side cover disposed on the second end of the cylindrical housing so as to cover the air-fuel ratio sensor element and defining an inside chamber for storing therein a gas to be measured, wherein the measured gas side cover has a nested structure composed of a plurality of cup-shaped cover members disposed one inside another, each of the cup-shaped cover members having a gas inlet hole formed in a side wall thereof for introducing the measured gas into the inside chamber of the measured gas side cover, and a bottom hole formed in a bottom wall thereof, and wherein the gas inlet hole of an innermost one of the plurality of cover members that directly faces the air-fuel ratio sensor element is offset from the detecting portion of the air-fuel ratio sensor element toward the housing in an axial direction of the air-fuel ratio sensor, and
• a partition structure for blocking flow communication of the measured gas between the gas inlet hole of each cover member and the bottom hole of each cover member,
• wherein the plurality of cover members of the measured gas side cover include an inner cover member forming the innermost cover member, an outer cover member disposed outside the inner cover member with a bottom wall thereof held in close contact with a bottom wall of the inner cover member, and an explosionproof cover disposed outside the outer cover member with a bottom wall thereof separated from the bottom wall of the outer cover member, and the partition structure includes the bottom walls of the inner and outer cover members held in close contact with each other, and a ring-shaped partition plate hermetically fitted in an annular space defined between the explosionproof cover member and the outer cover member and located adjacent to the bottom wall of the outer cover member.

An air-fuel ratio sensor comprising:

• a cylindrical housing having a first end and an opposite second end;
• an air-fuel ratio sensor element inserted through the cylindrical housing and capable of detecting an air-fuel ratio in an atmosphere of unburnt gas, the sensor element having a detecting portion for performing detection of the air-fuel ratio;
• an atmospheric side cover disposed on the first end of the cylindrical housing and defining an inside chamber for storing therein atmospheric air;
• and
• a measured gas side cover disposed on the second end of the cylindrical housing so as to cover the air-fuel ratio sensor element and defining an inside chamber for storing therein a gas to be measured, wherein the measured gas side cover has a nested structure composed of a plurality of cup-shaped cover members disposed one inside another, each of the cup-shaped cover members having a gas inlet hole formed in a side wall thereof for introducing the measured gas into the inside chamber of the measured gas side cover, and a bottom hole formed in a bottom wall thereof, and wherein the gas inlet hole of an innermost one of the plurality of cover members that directly faces the air-fuel ratio sensor element is offset from the detecting portion of the air-fuel ratio sensor element toward the housing in an axial direction of the air-fuel ratio sensor, and
• a partition structure for blocking flow communication of the measured gas between the gas inlet hole of each cover member and the bottom hole of each cover member,
• wherein the plurality of cover members of the measured gas side cover include an inner cover member forming the innermost cover member, an outer cover member disposed outside the inner cover member with a bottom wall thereof held in close contact with a bottom wall of the inner cover member, and an explosionproof cover disposed outside the outer cover member with a bottom wall thereof separated from the bottom wall of the outer cover member, and the partition structure includes the bottom walls of the inner and outer cover members held in close contact with each other, and a truncated hollow cone hermetically fitted in an annular space defined between the explosionproof cover member and the outer cover member and having a small diameter end engaged with a side wall the outer cover adjacent to the bottom wall of the outer cover member and an large diameter end engaged with a side wall of the explosionproof cover member adjacent to the bottom wall of the explosionproof cover member.

An air-fuel ratio sensor comprising:

• a cylindrical housing having a first end and an opposite second end;
• an air-fuel ratio sensor element inserted through the cylindrical housing and capable of detecting an air-fuel ratio in an atmosphere of unburnt gas, the sensor element having a detecting portion for performing detection of the air-fuel ratio;
• an atmospheric side cover disposed on the first end of the cylindrical housing and defining an inside chamber for storing therein atmospheric air;
• and
• a measured gas side cover disposed on the second end of the cylindrical housing so as to cover the air-fuel ratio sensor element and defining an inside chamber for storing therein a gas to be measured, wherein the measured gas side cover has a nested structure composed of a plurality of cup-shaped cover members disposed one inside another, each of the cup-shaped cover members having a gas inlet hole formed in a side wall thereof for introducing the measured gas into the inside chamber of the measured gas side cover, and a bottom hole formed in a bottom wall thereof, and wherein the gas inlet hole of an innermost one of the plurality of cover members that directly faces the air-fuel ratio sensor element is offset from the detecting portion of the air-fuel ratio sensor element toward the housing in an axial direction of the air-fuel ratio sensor, and
• a partition structure for blocking flow communication of the measured gas between the gas inlet hole of each cover member and the bottom hole of each cover member,
• wherein the plurality of cover members of the measured gas side cover include an inner cover member forming the innermost cover member, an outer cover member disposed outside the inner cover member with a bottom wall thereof held in close contact with a bottom wall of the inner cover member, and an explosionproof cover disposed outside the outer cover member with a bottom wall thereof separated from the bottom wall of the outer cover member, and the partition structure includes the bottom walls of the inner and outer cover members held in close contact with each other, and a part of a side wall of the explosionproof cover member being constricted in a radial inward direction so such that the constricted part of the side wall is in close contact with the bottom wall of the outer cover member.

An air-fuel ratio sensor comprising:

• a cylindrical housing having a first end and an opposite second end;
• an air-fuel ratio sensor element inserted through the cylindrical housing and capable of detecting an air-fuel ratio in an atmosphere of unburnt gas, the sensor element having a detecting portion for performing detection of the air-fuel ratio;
• an atmospheric side cover disposed on the first end of the cylindrical housing and defining an inside chamber for storing therein atmospheric air;
• and
• a measured gas side cover disposed on the second end of the cylindrical housing so as to cover the air-fuel ratio sensor element and defining an inside chamber for storing therein a gas to be measured, wherein the measured gas side cover has a nested structure composed of a plurality of cup-shaped cover members disposed one inside another, each of the cup-shaped cover members having a gas inlet hole formed in a side wall thereof for introducing the measured gas into the inside chamber of the measured gas side cover, and a bottom hole formed in a bottom wall thereof, and wherein the gas inlet hole of an innermost one of the plurality of cover members that directly faces the air-fuel ratio sensor element is offset from the detecting portion of the air-fuel ratio sensor element toward the housing in an axial direction of the air-fuel ratio sensor, and
• a partition structure for blocking flow communication of the measured gas between the gas inlet hole of each cover member and the bottom hole of each cover member,
• wherein the plurality of cover members of the measured gas side cover include an inner cover member forming the innermost cover member, an outer cover member disposed outside the inner cover member with a bottom wall thereof held in close contact with a bottom wall of the inner cover member, and an explosionproof cover disposed outside the outer cover member with a bottom wall thereof held in close contact with the bottom wall of the outer cover member, and the partition structure includes the bottom walls of the inner, outer and explosionproof cover members held in close contact with each other.