Exhaust Sensor Pipe Structure for Thermal Expansion and Leak Control
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Solution Overview
Problem
Existing exhaust devices face challenges in accurately measuring exhaust gas properties due to thermal expansion differences between catalyst units and connection pipes, leading to stress and potential leaks, which affect the accuracy and reliability of exhaust gas sensors.
Innovation Solution
The exhaust device design includes a connection pipe press-fitted into the catalyst unit, with a larger opening for the sensor, allowing relative displacement to accommodate thermal expansion, and an outer cylinder covering the connection to prevent leaks, while optimizing sensor placement and reducing the risk of gas escape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the exhaust gas sensor is inserted into the connection pipe, then the sensor can detect exhaust gas properties, but thermal expansion differences between the catalyst unit and connection pipe cause stress and potential leaks
Solution Approach 1:
The connection pipe is divided into multiple sections: a first connection pipe inserted into the catalyst unit, a second connection pipe forming a detection chamber, and a third connection pipe extending downstream. This segmentation allows each section to accommodate thermal expansion independently while maintaining the overall connection integrity and sensor functionality.
Solution Approach 2:
The first connection pipe is inserted into the second connection pipe, which is in turn inserted into the third connection pipe. This nested structure allows the inner pipes to move relative to outer pipes during thermal expansion, absorbing stress while maintaining sealed connections and proper sensor positioning.
2Stability of the object's composition
If the connection pipe is rigidly fixed to the catalyst unit, then structural stability is improved, but thermal expansion causes stress and potential leaks
Solution Approach 1:
The connection structure transitions from a rigid fixed connection to a dynamic nested insertion structure. The first connection pipe can move axially within the second and third connection pipes, allowing the system to adapt to thermal expansion dynamically while maintaining structural integrity and preventing leaks.
3Measurement precision
If the sensor detection portion is inserted into the connection pipe, then exhaust gas detection is enabled, but the sensor may be affected by thermal stress from the catalyst unit
Solution Approach 1:
The nested connection pipe structure acts as an intermediary between the hot catalyst unit and the exhaust gas sensor. The multiple pipe layers provide thermal isolation while allowing the sensor to detect exhaust gas properties, reducing thermal stress on the sensor and improving its operational reliability.
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 enhances the accuracy and reliability of exhaust gas measurements by minimizing stress and leaks, improving detection precision, and maintaining aesthetic appeal by incorporating a sound deadening chamber.
Implementation Method 1
thermal expansion differences between catalyst units and connection pipes
Data Source
AI summary
An exhaust device includes a catalyst unit, a connection pipe connected to a downstream side of the catalyst unit, an exhaust gas sensor that detects a state of exhaust gas flowing inside the connection pipe, and an outer cylinder that covers an outer periphery of the connection pipe. An upstream end portion of the connection pipe is press-fitted into an outlet of the catalyst unit. The connection pipe is fixed to a first baffle plate around the connection pipe at a position downstream of the upstream end portion. A first opening having an opening diameter larger than an outer diameter of the exhaust gas sensor is formed on a peripheral surface of the connection pipe, and the exhaust gas sensor is fixed to the outer cylinder in a state where a detection portion is inserted into an inside of the connection pipe through the first opening.