Gas concentration detection sensor
First Claim
1. A gas concentration detection sensor, comprising:
- a sensor element that detects concentration of a selected gas included in an object gas;
a first protection cover that covers over the sensor element and has a first gas introduction aperture allowing for a flow of the object gas from outside to inside of the first protection cover;
a second protection cover that covers over the first protection cover and has a second gas introduction aperture allowing for a flow of the object gas from outside to inside of the second protection cover; and
a gas flow path that runs from the second gas introduction aperture through a space between the first protection cover and the second protection cover to the first gas introduction aperture, enters inside of the first protection cover via the first gas introduction aperture, and reaches an edge of the sensor element,wherein at least one of the first protection cover and the second protection cover is provided with an inner wall member of a solid form or a hollow form with an internal enclosed space arranged to at least partially narrow width of a flow path from the second gas introduction aperture to the first gas introduction aperture in the gas flow path.
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Accused Products
Abstract
A flow path from outer gas introduction apertures 144a to inner gas introduction apertures 134a has a narrower-width flow passage formed by an inner wall member 150. This structure effectively lowers the probability that a liquid, such as water, entering from the outer gas introduction apertures 144a passes through a gas inflow chamber 122 and reaches a sensor element 110, compared with a structure without the inner wall member 150. The inner wall member 150 is formed as a solid member that is capable of storing the surrounding heat. Even if there is a certain event that has the potential of causing a temperature decrease of the sensor element 110, for example, an abrupt change in flow rate of an object gas, the heat stored in the inner wall member 150 effectively prevents a temperature decrease of the sensor element 110. This structure prevents the occurrence of cracking in the sensor element 110, compared with a conventional sensor structure having a double-layered protective cover.
24 Citations
10 Claims
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1. A gas concentration detection sensor, comprising:
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a sensor element that detects concentration of a selected gas included in an object gas; a first protection cover that covers over the sensor element and has a first gas introduction aperture allowing for a flow of the object gas from outside to inside of the first protection cover; a second protection cover that covers over the first protection cover and has a second gas introduction aperture allowing for a flow of the object gas from outside to inside of the second protection cover; and a gas flow path that runs from the second gas introduction aperture through a space between the first protection cover and the second protection cover to the first gas introduction aperture, enters inside of the first protection cover via the first gas introduction aperture, and reaches an edge of the sensor element, wherein at least one of the first protection cover and the second protection cover is provided with an inner wall member of a solid form or a hollow form with an internal enclosed space arranged to at least partially narrow width of a flow path from the second gas introduction aperture to the first gas introduction aperture in the gas flow path. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification