Atmospheric Side Cover Shoulder Design for Gas Sensor Sealing
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Solution Overview
Problem
Gas sensors installed in internal combustion engines face deformation due to high temperatures and pressures, leading to air gaps and incorrect sensor outputs, and existing solutions either fail to prevent deformation or increase manufacturing costs.
Innovation Solution
A gas sensor design featuring an atmospheric side cover with a large-diameter and small-diameter portion, a shoulder portion, and an air hole, which creates an outer space and communication path to direct leaking measurement gas outside, preventing it from entering the air atmosphere and reducing stress on the insulator porcelain, thus ensuring an air-tight seal and lowering manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the compressed sealing member is used to isolate the air atmosphere and measurement gas atmosphere, then the sensor can obtain correct outputs, but the sealing member deforms under high temperature and pressure, forming air gaps that allow gas leakage
Solution Approach 1:
The atmospheric side insulator porcelain acts as an intermediary barrier between the measurement gas atmosphere and the air atmosphere. By pressing this insulator against the device-side insulator, the patent creates a secondary sealing path that prevents gas leakage even when the primary sealing member deforms under high temperature and pressure conditions
Solution Approach 2:
The patent applies a biasing member to press the atmospheric side insulator porcelain against the device-side insulator beforehand, creating a pre-compression seal that compensates for the deformation of the compressed sealing member under operating conditions. This pre-positioning of the insulator ensures continuous sealing despite thermal and pressure-induced changes
2Reliability
If the atmospheric side insulator porcelain is pressed against the device-side insulator porcelain to prevent gas leakage, then gas cannot pass between them, but the enclosed space accumulates leaking gas that may eventually penetrate the seal
Solution Approach 1:
The atmospheric side cover is designed with differentiated local structures: a large-diameter portion that creates outer space adjacent to the seal, a small-diameter portion, and a shoulder portion with air holes. This local variation in geometry provides both the sealing pressure interface and the gas drainage pathway, allowing the system to maintain gas isolation while preventing harmful accumulation
3Object-generated harmful factors
If the base end surface of the atmospheric side insulator porcelain is shaped with irregularities to form gas drain paths, then gas can escape to air holes, but stress concentrates on the irregularities causing breakage risk
Solution Approach 1:
The shoulder portion of the atmospheric side cover serves as an intermediary structure that provides air holes for gas drainage without requiring irregularities on the insulator porcelain surface. The air holes are formed in the cover itself, which is more resistant to stress concentration, thereby maintaining the strength of the insulator porcelain while achieving effective gas drainage
4Object-generated harmful factors
If irregularities are formed on the base end surface of the atmospheric side insulator porcelain, then gas drain paths are created, but the configuration becomes complicated increasing manufacturing cost
Solution Approach 1:
The atmospheric side cover with air holes acts as an intermediary component that provides gas drainage functionality without modifying the atmospheric side insulator porcelain structure. This separates the drainage function from the insulator, maintaining its simple cylindrical configuration and reducing manufacturing complexity while still achieving effective gas escape paths
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 effectively prevents measurement gas from entering the air atmosphere, ensuring accurate sensor outputs, avoiding breakage of the insulator porcelain, and reducing manufacturing costs by simplifying the structure and facilitating heat dissipation through the communication path.
Implementation Method 1
a shoulder portion which is formed between the small-diameter portion and the large-diameter portion to press a base end surface of the atmospheric side insulator porcelain to the front end side
Implementation Method 2
an outside path which is formed inside the small-diameter portion in communication with the air hole, a communication path which is formed between the detached portion and the biasing member to establish communication between the outer space and the outside path
Implementation Method 3
a biasing member to press the atmospheric side insulator porcelain against the device-side insulator porcelain
Data Source
AI summary
A gas sensor includes a sensor device, a device-side insulator porcelain, an atmospheric side insulator porcelain, a housing, a seal disposed between the housing and the device-side insulator porcelain, and an atmospheric side cover. The atmospheric side cover includes a large-diameter portion, a small-diameter portion, and a shoulder portion formed therebetween. The shoulder portion presses a base end surface of the atmospheric side insulator porcelain to a front end side through a biasing member to place the atmospheric side insulator porcelain in contact with the device-side insulator porcelain. The shoulder portion is defined by a contact portion placed in contact with the biasing member and a detached portion separate from the biasing member to form a communication path which communicates between an outer space and an outside path. This avoids entry of measurement gas into an air atmosphere within the atmospheric side insulator porcelain to obtain correct sensor outputs, also avoids breakage of the atmospheric side insulator porcelain, and reduces the manufacturing costs.