Exhaust Gas Sensor Holding Member Design for Filter Stability
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Solution Overview
Problem
Conventional sensors for exhaust gas purifying apparatuses face issues with excessive stress on examining filters due to vibrations, leading to potential damage and inaccurate PM measurement over time, as they are either not properly held or have reduced exposed filter areas when held more securely.
Innovation Solution
A sensor design that holds the examining filter with a holding member covering 10% to 50% of its peripheral area, ensuring stable attachment while maintaining a significant filter area for accurate PM measurement, and includes a sealing part to prevent PM deposition on the holding member side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the examining filter is held with a larger area, then the stability and reduced stress on the filter is improved, but the area of the filter exposed to exhaust gas decreases leading to reduced measurement accuracy
Solution Approach 1:
The holding member is designed to hold only a specific portion (10% to 50% part by area) of the peripheral portion of the examining filter, rather than holding the entire filter. This segmentation allows the filter to be securely held while maintaining sufficient exposed area for accurate PM measurement.
Solution Approach 2:
The holding member is positioned to cover only the peripheral portion of the examining filter, creating a local holding arrangement. This localized holding approach provides stability where needed while preserving the central and majority areas of the filter for exhaust gas exposure and measurement.
2Measurement precision
If the examining filter is not held securely, then the filter area exposed to exhaust gas is maintained, but excessive stress from vibrations damages the filter over time
Solution Approach 1:
The holding member applies holding action to only a partial area (10% to 50% part by area) of the examining filter's peripheral portion. This partial holding action is sufficient to prevent vibration damage while excessive holding area is avoided to maintain measurement accuracy.
3Reliability
If the holding member covers more than 50% of the peripheral portion, then the filter is held more stably, but the PM concentration measurement becomes inaccurate
Solution Approach 1:
The patent specifies a quantitative parameter range (10% to 50% part by area) for the holding member coverage of the peripheral portion. This parameter optimization ensures the holding member provides sufficient stability while leaving adequate filter area exposed for accurate PM concentration measurement.
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
This design effectively reduces stress on the examining filter, preventing damage while ensuring accurate measurement of PM concentration and presence, allowing for proper regeneration and leak detection in the diesel particulate filter.
Implementation Method 1
the holding member holds a 10% to 50% part by area of a peripheral portion of the examining filter so as to cover the part from a peripheral side of the examining filter... it is possible to reduce application of stress on the examining filter
Implementation Method 2
capable of estimating the amount of PM deposition in the DPF by measuring a difference in pressure across the examining filter in the secondary exhaust line
Implementation Method 3
the examining filter may include a sealing part facing an inflow side of the secondary exhaust line, and be held by the holding member on an outflow side of the secondary exhaust line
Data Source
Figure 1~2
Figure 3~4
AI summary
A sensor (20) for an exhaust gas purifying apparatus includes an examining filter (28) provided in a secondary exhaust line (22) diverging from the primary exhaust line (14) of an internal combustion engine (12); and a holding member configured to hold the examining filter on the secondary exhaust line. The holding member (26) holds a 10% to 50% part by area of a peripheral portion (28A) of the examining filter (28) so as to cover the part from a peripheral side of the examining filter (28).