Sintered Metal Jacketing for Thermal Flow Sensor Core
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Solution Overview
Problem
Existing thermal flow measuring devices face challenges in establishing a reliable thermal contact between the metal shell and sensor core without using potting compounds, and there is a risk of sensor damage due to non-uniform mechanical loading during manufacturing.
Innovation Solution
A method involving metal powder injection molding to create a metal jacketing with a blind hole, which encloses a sensor core with a ceramic core and wound metal wire, allowing for sintering to establish a secure thermal contact and minimize damage risks by ensuring a tight fit through shrinkage, eliminating the need for potting compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal shell is pressed onto a sensor core by hydroforming to avoid potting compound, then thermal contact is improved, but the sensor element is damaged due to non-uniform mechanical loading
Solution Approach 1:
The patent changes the physical state and dimensions of the metal shell through controlled sintering. The shell is manufactured with an initial outer diameter slightly larger than the sensor core diameter, and during sintering, it shrinks to achieve uniform tight contact. This parameter change approach replaces the harmful high-pressure hydroforming with a controlled thermal process that achieves the same contact quality without damaging the sensor element.
Solution Approach 2:
The patent performs preliminary sizing of the metal shell before final assembly. The shell is manufactured with predetermined dimensions (outer diameter slightly larger than sensor core) that account for the expected shrinkage during sintering. This preliminary action ensures that after sintering, the shell achieves the correct fit without requiring additional high-pressure forming operations that could damage the sensor core.
2Reliability
If use of a potting compound is necessary to establish thermal contact, then thermal contact is improved, but device complexity and manufacturing steps increase
Solution Approach 1:
The patent extracts and eliminates the potting compound from the manufacturing process. Instead of using a separate bonding material, the invention creates a direct metal-to-metal thermal contact through controlled shrinkage of the metal shell during sintering. This removes the need for additional materials and simplifies the manufacturing process while maintaining reliable thermal contact.
Solution Approach 2:
The metal shell performs multiple functions: it provides structural protection, electrical insulation, and thermal contact. Through the sintering process, the shell automatically achieves the correct fit and thermal connection without requiring external potting compounds or additional bonding operations. The shell essentially services its own assembly requirement through controlled dimensional change.
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 method ensures a strong, impermeable, and stable thermal contact between the metal jacketing and sensor core, reducing the risk of damage during manufacturing and eliminating the need for potting compounds, while maintaining effective thermal measurement capabilities.
Implementation Method 1
sintering the metal jacketing
Implementation Method 2
the jacketing shrinks during the sintering
Data Source
AI summary
The present disclosure relates to a method for manufacturing a sensor for a thermal, flow measuring device. The method includes, in such case, manufacturing a metal jacketing for a sensor core, introducing the sensor core into the metal jacketing and sintering the metal jacketing with introduced sensor core.