Gas Sensor Laminar Flow Design for Responsiveness
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Solution Overview
Problem
Conventional gas sensors face challenges in maintaining responsiveness when the detection element's length is reduced, leading to potential deterioration in gas flow and detection accuracy due to turbulent gas flow patterns and proximity issues with heat sources.
Innovation Solution
A gas sensor design where the detection element's forward end is positioned closer to the base end within a tubular metallic shell, with a tubular protector inserted to create a gas introduction space that guides the gas-to-be-detected through gas introduction holes, ensuring a laminar flow along the detection section, thereby enhancing responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the detection element length is decreased to reduce cost, then the amount of platinum used is reduced, but the responsiveness deteriorates due to turbulent gas flow
Solution Approach 1:
The gas flow path is segmented into distinct regions: a gas introduction space formed by the metallic shell and protector, and a detection section. Gas introduction holes are positioned to create a controlled flow path that guides gas laminarly along the detection element, preventing turbulence even with shortened detection element length.
Solution Approach 2:
The protector acts as an intermediary component between the metallic shell and the detection element. It creates a gas introduction space that mediates the gas flow, directing it smoothly over the detection section and ensuring laminar flow conditions are maintained despite the shortened detection element configuration.
2Object-affected harmful factors
If the detection section is disposed on the base end side with respect to the forward end of the metallic shell, then connection terminals are protected from heat, but gas flow becomes difficult along the detection section
Solution Approach 1:
The gas introduction holes are positioned in a different spatial dimension relative to the detection section. By placing the holes on the forward end side of the metallic shell while the detection section extends to the base end side, a three-dimensional gas introduction space is created that enables gas to flow laminarly along the detection element from the holes toward the base end, overcoming the positional challenge.
3Ease of manufacture
If the detection element is shortened, then manufacturing cost is reduced, but the gas flow pattern becomes turbulent affecting detection accuracy
Solution Approach 1:
The flow regime parameter is changed from turbulent to laminar through the introduction of the gas introduction space and properly positioned gas introduction holes. This parameter change ensures smooth gas flow along the shortened detection element, maintaining detection accuracy while allowing for cost-effective manufacturing with reduced material usage.
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
The design ensures smooth gas flow along the detection element, maintaining or improving responsiveness even when the detection element is shortened, reducing material costs and heat-related issues.
Implementation Method 1
a forward-end-side inner surface of the metallic shell and an outer surface of the protector form therebetween a gas introduction space for guiding the gas-to-be-detected from a region on the forward end side with respect to the metallic shell to the gas introduction hole of the protector
Data Source
AI summary
A protector (160) is inserted into a metallic shell (110) such that at least a portion of each gas introduction hole (167) is located on the base end side with respect to the forward end (110b) of the metallic shell. The metallic shell has a gas introduction space S2 defined by a forward-end-side inner surface (113b) of the metallic shell and an outer surface (160d) of the protector and which guides a gas-to-be-detected (exhaust gas G) from a region on the forward end side of the metallic shell into the gas introduction holes of the protector. The base end of the forward end portion (121) of the detection element (120) is located on the base end side with respect to the forward end (167b) of each gas introduction hole, and the forward end of the forward end portion is located on the forward end side with respect to the base end (167c) of each gas introduction hole.