MEMS-Coupled Screw Head Sensing for Non-Invasive Load Measurement
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Solution Overview
Problem
Existing mechanical coupling devices, such as screws and bolts, require invasive interventions and dedicated components for strain measurement, which are costly, dimensionally limited, and require complex calibration.
Innovation Solution
A microelectromechanical sensor (MEMS) is externally coupled to the screw, allowing non-invasive measurement of surface deformations at the screw head, correlating these deformations to physical quantities like tightening torque and load strength without altering the screw's structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gauges are inserted in a hole made on the screw, then the load strength of the screw can be measured, but the structural characteristics of the screw are significantly altered and the solution is limited to screws with large dimensions
Solution Approach 1:
A magnetic field serves as an intermediary between the external magnet and the strain gauge, allowing the strain gauge to be positioned outside the screw while still measuring internal deformations. The magnetic field transmits force through the screw material without requiring physical insertion or modification of the screw structure.
Solution Approach 2:
The patent replaces direct mechanical contact (inserting strain gauges into holes) with a magnetic field-based measurement system. The external magnet generates a magnetic field that interacts with the screw material, enabling non-contact measurement of internal stresses and deformations.
2Measurement precision
If strain gauges are applied on the faces of the screw head, then the load strength can be monitored, but the screw must have sufficiently large dimensions to house the strain gauges
Solution Approach 1:
The magnetic field acts as an intermediary that allows measurement capabilities to be decoupled from the screw dimensions. The external magnet and strain gauge configuration can measure deformations in screws of any size without requiring the screw itself to accommodate the measurement devices.
Solution Approach 2:
The external magnetic field measurement system provides universal applicability across different screw sizes and types. The same measurement principle can be applied to small, medium, and large screws without modification, making the solution universally adaptable.
3Measurement precision
If a pull rod with elastomer and strain gauges is inserted in the screw, then the preload and flexure state can be detected with precision, but invasive drilling is required on the screw
Solution Approach 1:
The magnetic field serves as an intermediary that eliminates the need for invasive drilling and pull rod insertion. The external magnet generates a magnetic field that penetrates the screw material, allowing the strain gauge to measure internal deformations without physical access to the screw interior.
Solution Approach 2:
The patent replaces the mechanical pull rod system with a magnetic field-based measurement approach. Instead of physically inserting a pull rod through drilled holes, the magnetic field transmits measurement capabilities through the screw material non-invasively.
4Measurement precision
If deformation detection sensors are applied on the faces of a nut, then the preload force can be detected, but the nut must have sufficient dimensions and dedicated machining is required
Solution Approach 1:
The magnetic field acts as an intermediary that allows deformation measurement without modifying the nut structure. The external magnet generates a magnetic field that interacts with the screw-nut assembly, enabling measurement of preload forces without drilling, machining, or integrating electronic circuits into the nut.
Solution Approach 2:
The patent replaces the complex mechanical and electronic integration required in the nut with a magnetic field-based measurement system. This substitution eliminates dedicated machining requirements and simplifies the overall device complexity while maintaining measurement precision.
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 MEMS sensor provides high-resolution, non-invasive measurement of mechanical coupling parameters, reducing costs and complexity, and enabling universal application across various screw sizes and types, while maintaining precision and accuracy.
Implementation Method 1
a microelectromechanical sensor, of a MEMS (Micro Electro Mechanical Sensor) type, having a high resolution for measuring surface micro-deformations
Data Source
Figure 1~2
Figure 3
Figure 4A~4B
AI summary
A mechanical coupling device (2) is described, provided with a microelectromechanical sensor (1), which includes in an integrated manner: a detection structure (10), of a MEMS type, made in a die (11) of semiconductor material, externally coupled to a surface portion of the mechanical coupling device (2) to detect deformations thereof and generate a corresponding detection signal (Sr); and an electronic circuit (12), operatively coupled to the detection structure (10) and configured to receive and process the detection signal (Sr) to generate an output signal (Sout). The output signal (Sout) is correlated to physical quantities associated with deformations and indicative of operating conditions of the mechanical coupling device (2).