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Exhaust Gas Sensor with High Water Splash Resistant Layer for Lower Emission
Technical Paper
2020-01-0565
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
Increasingly stringent regulations call for the reduction of emissions at engine
startup to purify exhaust gas and reduce the amount of CO2 emitted.
Air-fuel ratio (A/F) sensors detect the composition of exhaust gas and provide
feedback to control the fuel injection quantity in order to ensure the optimal
functioning of the catalytic converter. Reducing the time needed to obtain
feedback control and enabling the restriction-free installation of A/F sensors
can help meet regulations. Conventional sensors do not activate feedback control
immediately after engine startup as the combination of high temperatures and
splashes of condensed water in the exhaust pipe can cause thermal shock to the
sensor element. Moreover, sensors need to be installed near the engine to
increase the catalyst reaction efficiency. This increases the possibility of
water splash from the condensed water in the catalyst. Therefore, to achieve
both a quick feedback control and restriction-free installation, the development
of a high water splash resistance exhaust gas sensor is necessary. As a means to
improve water splash resistance, we focused on the water repellent function of
the Leidenfrost effect. We discovered that the water repellent function of the
Leidenfrost effect appeared when the thermal conductivity of the water splash
resistant layer is 1W/m·K or higher in the range of sensor control temperature.
In addition, by adopting α-Al2O3 in the aggregate of water
splash resistant layer and keeping the porosity within 30% to 40%, we were able
to achieve both good sensor responsiveness and water repellent function, which
normally contradict each other. Adopting a water splash resistant layer with
water-repellent function significantly improved the water splash toughness,
enabling both a quick feedback control immediately after engine startup and
restriction-free installation.
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Citation
Imada, S., Ushikubo, T., Nishijima, H., Miyake, Y. et al., "Exhaust Gas Sensor with High Water Splash Resistant Layer for Lower Emission," SAE Technical Paper 2020-01-0565, 2020, https://doi.org/10.4271/2020-01-0565.Data Sets - Support Documents
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References
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