Particulate Matter Sensor Cover and Detection Unit Alignment
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Solution Overview
Problem
The existing particulate matter detection sensors require precise control of assembly angles to maintain detection accuracy, increasing the number of assembly steps and costs due to the need for the deposition portion and introduction holes to be oriented upstream of the exhaust gas flow direction.
Innovation Solution
A particulate matter detection sensor design where the deposition portion is oriented towards the tip of the cover member, with multiple exhaust gas introduction holes positioned closer to the tip than the deposition portion, allowing for stable gas flow and efficient particulate matter deposition without requiring precise assembly angle control, and additional features such as balanced hole arrangements and rectifying members to enhance detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the deposition portion and introduction hole are oriented upstream of the exhaust gas flow direction to improve detection accuracy, then the detection accuracy of particulate matter is improved, but the assembly angle must be precisely controlled, increasing the number of assembly steps and cost
Solution Approach 1:
The sensor is divided into a detection unit and a cover unit that can be assembled independently. The cover unit includes the introduction holes positioned upstream, while the detection unit contains the deposition portion. This segmentation allows each unit to be manufactured and positioned separately, eliminating the need for precise angular alignment during assembly.
Solution Approach 2:
The design transitions from requiring precise angular orientation in the flow direction to a configuration where the upstream positioning of introduction holes and the deposition portion automatically ensures proper alignment. The exhaust gas flow itself serves as the alignment mechanism, eliminating the need for controlled assembly angles.
2Measurement precision
If the deposition portion is oriented perpendicular to the axial direction to improve detection accuracy, then the detection accuracy is improved, but the assembly process becomes more complex with increased steps and cost
Solution Approach 1:
Instead of orienting the deposition portion perpendicular to the axial direction and requiring complex assembly to align it with the flow, the design inverts the approach by positioning the introduction holes upstream in the cover. The exhaust gas flow naturally directs particles onto the deposition portion, achieving the perpendicular orientation benefit without the assembly complexity.
3Measurement precision
If precise assembly angle control is implemented to maintain detection accuracy, then the detection accuracy is maintained, but the manufacturing cost and number of assembly steps increase
Solution Approach 1:
The cover unit with upstream-positioned introduction holes and the detection unit with the deposition portion are designed to self-align during assembly. The exhaust gas flow pattern and the geometric arrangement of components ensure that particles are naturally directed onto the deposition portion without requiring precise angular control, thereby maintaining detection accuracy while improving assembly efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Improves assembling workability and detection accuracy by allowing the sensor to function effectively regardless of assembly angle changes, with stable gas flow and efficient particulate matter deposition, and further enhances detection by separating contaminants and moisture.
Implementation Method 1
an output of an electrical signal is changed according to change of electrical characteristics due to the deposition of the particulate matter on the deposition portion
Implementation Method 2
a deposition portion on which a part of particulate matter contained in an exhaust gas discharged from an internal combustion engine is deposited
Data Source
AI summary
A particulate matter detection sensor includes a particulate matter detection unit for changing the output of an electrical signal in accordance with change in the electrical characteristics due to the deposition of particulate matter contained in an exhaust gas G discharged from an internal combustion engine, and a cover member having a cylindrical cover wall and disposed to surround the particulate matter detection unit. The particulate matter detection unit includes a deposition portion on which a part of the particulate matter is deposited, and a plurality of detection electrodes disposed being spaced apart from each other on the deposition portion. The deposition portion of the particulate matter detection unit is arranged so as to be oriented towards the tip side of the cover member. The cover wall of the cover member includes a plurality of exhaust gas introduction holes formed at positions closer to the tip side than is the deposition portion.