Abstract: A sensor element includes: an element base including: a ceramic body made of an oxygen-ion conductive solid electrolyte, and having a gas inlet at one end portion thereof; at least one internal chamber located inside the ceramic body, and communicating with the gas inlet under predetermined diffusion resistance; an electrochemical pump cell including an electrode located on an outer surface of the ceramic body, an electrode facing the chamber, and a solid electrolyte located therebetween; and a heater buried in the ceramic body, and an leading-end protective layer being porous, and covering a leading end surface and four side surfaces in a predetermined range of the element base on the one end portion. The leading-end protective layer has an extension extending into the gas inlet, and fixed to an inner wall surface of the ceramic body demarcating the gas inlet.

Abstract: A wetting test apparatus for a gas sensor includes: a pipe having a flow path therein; a blower for allowing a gas to flow through the flow path; a water supplier for supplying moisture to the flow path; at least one gas sensor for detecting at least one component of the gas flowing through the flow path; and a pressure variation generator for generating variations in a pressure of the gas flowing through the flow path by changing an effective cross-sectional area of the flow path.

Abstract: An apparatus for evaluating a response time of gas sensors includes: a pipe; a first gas supplier for supplying a first gas to the pipe; a second gas adding machine for adding a second gas to the first gas in the pipe; and gas sensors for detecting components in a mixed gas of the first gas and the second gas, each of the gas sensors being attached to the pipe on a downstream side of an addition position of the second gas in a flow direction of the first gas. The second gas adding machine includes: a supply source of the second gas; a connecting pipe for connecting the supply source to the pipe; and a connecting pipe on-off valve for opening and closing the connecting pipe.

Abstract: A sensor element includes: an element base including: a ceramic body made of an oxygen-ion conductive solid electrolyte, and having a gas inlet at one end portion thereof; at least one internal chamber located inside the ceramic body, and communicating with the gas inlet under predetermined diffusion resistance; an electrochemical pump cell including an electrode located on an outer surface of the ceramic body, an electrode facing the chamber, and a solid electrolyte located therebetween; and a heater buried in the ceramic body, and an leading-end protective layer being porous, and covering a leading end surface and four side surfaces in a predetermined range of the element base on the one end portion. The leading-end protective layer has an extension extending into the gas inlet, and fixed to an inner wall surface of the ceramic body demarcating the gas inlet.

Abstract: A wetting test apparatus for a gas sensor includes: a pipe having a flow path therein; a blower for allowing a gas to flow through the flow path; a water supplier for supplying moisture to the flow path; at least one gas sensor for detecting at least one component of the gas flowing through the flow path; and a pressure variation generator for generating variations in a pressure of the gas flowing through the flow path by changing an effective cross-sectional area of the flow path.

Abstract: An apparatus for evaluating a response time of gas sensors includes: a pipe; a first gas supplier for supplying a first gas to the pipe; a second gas adding machine for adding a second gas to the first gas in the pipe; and gas sensors for detecting components in a mixed gas of the first gas and the second gas, each of the gas sensors being attached to the pipe on a downstream side of an addition position of the second gas in a flow direction of the first gas. The second gas adding machine includes: a supply source of the second gas; a connecting pipe for connecting the supply source to the pipe; and a connecting pipe on-off valve for opening and closing the connecting pipe.

Abstract: A gas sensor includes a sensor element that includes a gas inlet through which a measurement target gas is introduced into the sensor element and a protective cover that contains a substance having a capability of decomposing ammonia. The protective cover has a gas-contact surface area within a range of 450 mm2 to 1145 mm2, the gas-contact surface area being a sum of a surface area of a portion facing the inlet-side gas flow path and a surface area of a portion facing an in-element-chamber flow path of the sensor element chamber that is a shortest flow path for the measurement target gas from the element-chamber inlet to the gas inlet.

Abstract: The gas sensor 100 has a gas flow channel 127 formed therein by an inner protection cover 130. The gas flow channel 127 is formed in the pathway of measured gas from a first outer gas hole 144a formed in an outer protection cover 140 that covers the tip end of a sensor element 110 to a gas inlet port 111 of the sensor element 110. The gas flow channel 127 extends from the rear end side to the tip end side of the sensor element 110 and is open to the sensor element chamber 124 having the gas inlet port 111 disposed therein.

Abstract: A gas sensor includes a sensor element that includes a gas inlet through which a measurement target gas is introduced into the sensor element and a protective cover that contains a substance having a capability of decomposing ammonia. The protective cover has a gas-contact surface area within a range of 450 mm2 to 1145 mm2, the gas-contact surface area being a sum of a surface area of a portion facing the inlet-side gas flow path and a surface area of a portion facing an in-element-chamber flow path of the sensor element chamber that is a shortest flow path for the measurement target gas from the element-chamber inlet to the gas inlet.

Abstract: The gas sensor 100 has a gas flow channel 127 formed therein by an inner protection cover 130. The gas flow channel 127 is formed in the pathway of measured gas from a first outer gas hole 144a formed in an outer protection cover 140 that covers the tip end of a sensor element 110 to a gas inlet port 111 of the sensor element 110. The gas flow channel 127 extends from the rear end side to the tip end side of the sensor element 110 and is open to the sensor element chamber 124 having the gas inlet port 111 disposed therein.

Abstract: In a gas sensor, a ratio A2/A1 defined by a ratio of an opening area A1 per first inner gas hole and an opening area A2 per second inner gas hole is set to higher than or equal to 0.9 and lower than or equal to 3.8 and, more preferably, to higher than or equal to 1.5 and lower than or equal to 1.9. Accordingly, adhesion of water to a sensor element can be sufficiently prevented. In addition, a ratio B2/B1 defined by a ratio of a total opening area B1 of the first inner gas holes to a total opening area B2 of the second inner gas holes is set to higher than or equal to 0.85 and, more preferably, higher than or equal to 1.5. Accordingly, adhesion of water to the sensor element can be more reliably, effectively prevented.

Abstract: A gas sensor is provided with a multilayer body of solid electrolyte layers, a measurement electrode, a reference electrode, a reference gas introduction layer, a detection unit and a heater. The reference electrode and the measurement electrode are formed directly on the same first solid electrolyte layer. Thus, heat from the heater is transferred from a third substrate layer to the first solid electrolyte layer, and also to the reference electrode and the measurement electrode through the same first solid electrolyte layer. The reference electrode is covered with a reference gas introduction layer, formed of a porous body. The transference of heat from the heater to the reference electrode through the reference gas introduction layer is smaller than the transference of heat from the heater to the reference electrode through the first solid electrolyte layer on which the reference electrode is formed directly.

Abstract: A gas sensor is provided with a multilayer body of solid electrolyte layers, a measurement electrode, a reference electrode, a reference gas introduction layer, a detection unit and a heater. The reference electrode and the measurement electrode are formed directly on the same first solid electrolyte layer. Thus, heat from the heater is transferred from a third substrate layer to the first solid electrolyte layer, and also to the reference electrode and the measurement electrode through the same first solid electrolyte layer. The reference electrode is covered with a reference gas introduction layer, formed of a porous body. The transference of heat from the heater to the reference electrode through the reference gas introduction layer is smaller than the transference of heat from the heater to the reference electrode through the first solid electrolyte layer on which the reference electrode is formed directly.