Single-Sided Welded Sensor Element for Deformation Measurement
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Solution Overview
Problem
Existing measuring devices face challenges in achieving high accuracy and long service life due to material tensions and increased manufacturing effort caused by welding sensor elements to metal bodies, and redundant measuring bridge arrangements that fail to distinguish between measurement-related and environmental effects like aging and corrosion.
Innovation Solution
A measuring device with a metal body deformed by the value to be measured, featuring a sensor element with metal thin-film ohmic resistors welded to the body in a way that completely encloses the metal carrier, reducing residual tensions and allowing for accurate deformation detection through a single-sided welding process, and multiple Wheatstone bridges aligned at different angles for comprehensive deformation analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the sensor element is welded to the metal body from both sides, then the connection strength is improved, but the manufacturing complexity and handling effort increase
Solution Approach 1:
The patent transitions from two-sided welding (working from both faces of the strap) to single-sided welding by extending the weld into the material thickness dimension. The weld penetrates through the entire thickness t of the metal body from one side, eliminating the need for second-sided welding while maintaining connection strength.
Solution Approach 2:
The sensor element is inserted into the metal body before welding, positioning it such that the weld can enclose the carrier from one side. This preliminary positioning allows the welding process to create a complete enclosure without requiring subsequent operations from the opposite side.
2Reliability
If the weld extends into the material thickness of the metal body, then the connection reliability is improved, but material tensions at the weld root increase
Solution Approach 1:
The patent converts the potentially harmful effect of weld penetration into a beneficial enclosure structure. By extending the weld through the material thickness to enclose the sensor carrier, the design transforms what could be a stress concentration point into a protective encapsulation that secures the sensor element while maintaining structural integrity.
3Measurement precision
If thin-film resistors are applied to the sensor element, then the measurement precision is improved, but creeping effects from separation may occur
Solution Approach 1:
The patent replaces mechanical bonding methods with metal thin-film technology for attaching resistors to the sensor carrier. The thin-film resistors are deposited directly onto the carrier surface, creating a molecular-level adhesion that eliminates creeping effects associated with mechanical separation while maintaining measurement precision.
4Adaptability or versatility
If multiple Wheatstone bridges are used for comprehensive measurement, then the measurement capability is improved, but the device complexity increases
Solution Approach 1:
The patent implements multiple Wheatstone bridges on a single sensor element, where each bridge can detect different deformation components (e.g., axial, radial, tangential stresses). This multi-functional arrangement allows one sensor element to perform comprehensive mechanical characterization, replacing what would otherwise require multiple separate sensors.
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 configuration enhances manufacturing ease, measurement accuracy, and service life by preventing creeping effects and allowing precise detection of deformations with reduced material tensions and redundant measurement capabilities.
Implementation Method 1
deformations of a body made of metal to which the value to be measured is applicable are electrically detected by means of changes of ohmic resistances due to deformation
Implementation Method 2
the sensor element being connected to the metal body by welding
Data Source
AI summary
A measuring device is described which has a metal body deformable in accordance with a value to be measured. A sensor element having a metal carrier and ohmic resistors formed thereon in metal thin-film technique is connected to the metal body by welding and generates a signal adapted to be electrically evaluated which corresponds to the deformation of the metal body. The weld for connecting the metal body and the sensor element completely encloses the metal carrier at its circumference. The metal body has, at the welded connection with the metal carrier, a material thickness t which is completely penetrated by the weld. The value to be measured by the measuring device comprises force, pressure, temperature, torque or combinations thereof.