Method and system for exhaust particulate matter sensing
AssigneeFord Global Technologies, LLC
InventorXiaogang Zhang
Life of this patent
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Abstract
Methods and systems are provided for a particulate matter sensor positioned downstream of a diesel particulate filter in an exhaust system. In one example, a particulate matter sensor assembly may include an outer stepped tube, an inner stepped tube positioned within the outer tube, and a plate having sensor element positioned inside the inner tube, the inner and the outer tube generating a step in the assembly. The step may block larger contaminants and water droplets, and thereby stopping them from impinging on the sensor element positioned within the assembly.
Claims20
A particulate matter sensor assembly, comprising:
- an outer stepped tube having a first semi-circular region and a second semi-circular region, the first region being longer than the second region;
- an inner stepped tube coaxial to the outer stepped tube having a third semi-circular region and a fourth semi-circular region, the third region being longer than the fourth region;
- and
- a plate positioned inside the inner stepped tube having a sensor element.
A method, comprising:
- directing a portion of exhaust gas in an exhaust passage into a particulate matter sensor in a direction opposite to exhaust flow in the exhaust passage via inlets in a step;
- guiding the portion of the exhaust gas into a first region;
- spiraling the portion of the exhaust gas from the first region into a second region, the second region being fluidically coupled to the first region;
- flowing the portion of the exhaust gas from the second region into a third region via a first slit on the third region towards sensor electrodes on a plate in a direction opposite to the exhaust flow in the exhaust passage;
- streaming the portion of the exhaust gas via a second slit positioned on the plate into a fourth region, the plate separating the third region and the fourth region;
- and
- steering the portion of the exhaust gas via a bottom surface of the fourth region towards the exhaust passage in a direction orthogonal to the exhaust flow in the exhaust passage.
A system, comprising:
- a particulate matter (PM) sensor located downstream of a particulate filter in an exhaust passage, the PM sensor having an asymmetric protection tube including a step wherein the asymmetric protection tube includes a first segment coupled to a second segment, the first segment being longer than the second segment, and further wherein a difference in lengths between the first segment and the second segment generates the step.
Dependencies are inferred from the claim text.