Elliptically Magnetized Torque Sensor Shaft for Zero-Torque Diagnostics
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Solution Overview
Problem
Existing torque sensor systems with circumferentially magnetized shafts face challenges in efficiently and cost-effectively producing a measurable axial field component at zero torque, making it difficult to diagnose proper magnetization and requiring cumbersome and expensive processes for large volume production.
Innovation Solution
The implementation of an elliptically magnetized shaft with a nonzero axial component at zero torque, achieved through methods such as using magnetizing clamps or electromagnets oriented at an oblique angle, allows for diagnostic testing and efficient production by ensuring a measurable axial field component, enabling proper magnetization verification and calibration without the need for external torque application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shaft is circumferentially magnetized, then the torque sensing function is achieved, but the lack of axial field component at zero torque prevents simple passive diagnostics and increases manufacturing complexity
Solution Approach 1:
The patent applies asymmetry by magnetizing the shaft in an elliptical pattern rather than a symmetric circumferential pattern. This elliptical magnetization creates an asymmetric magnetic field distribution that produces a measurable axial field component at zero torque, enabling passive diagnostics without adding complex active diagnostic systems.
Solution Approach 2:
The patent transitions from a two-dimensional circumferential magnetization pattern to a three-dimensional elliptical magnetization pattern that includes an axial component. This dimensional change allows the magnetic field to have both circumferential and axial components, providing a measurable signal at zero torque for diagnostic purposes.
2Reliability
If the shaft is magnetized under predetermined torque to create quiescent axial field, then diagnostics at zero torque are enabled, but the manufacturing process becomes cumbersome and expensive
Solution Approach 1:
The patent applies preliminary action by establishing the elliptical magnetization pattern during the initial shaft manufacturing process rather than requiring subsequent complex magnetization steps under predetermined torque. This allows the shaft to be pre-magnetized in the correct elliptical configuration before assembly, simplifying the overall manufacturing process.
Solution Approach 2:
The patent changes the magnetization parameters from a simple circumferential pattern to an elliptical pattern with specific axial and circumferential components. This parameter change enables the shaft to produce a measurable axial field at zero torque while allowing for simpler, more cost-effective manufacturing processes.
3Measurement precision
If circumferential magnetization is used, then torque sensing is achieved, but manufacturing errors and magnetization weakening lead to complete system failure
Solution Approach 1:
The patent incorporates feedback mechanisms through the elliptical magnetization design, where the axial field component at zero torque serves as a diagnostic indicator. This feedback allows the system to detect and signal magnetization degradation or manufacturing errors before complete failure occurs, enabling proactive maintenance and system reliability monitoring.
Solution Approach 2:
The elliptical magnetization is established as a preliminary condition during manufacturing that creates built-in diagnostic capability. This preliminary action ensures that the shaft has a measurable axial field component from the start, allowing for early detection of magnetization weakening or manufacturing defects throughout the product lifecycle.
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 solution provides a cost-effective and efficient means to produce torque sensors with a measurable axial field component at zero torque, facilitating diagnostic testing and ensuring proper magnetization, thereby improving the reliability and ease of production of torque sensor systems.
Implementation Method 1
the rotating shaft, or one or more axial portions thereof, may be circumferentially magnetized
Implementation Method 2
When torque is applied to the shaft, the circumferential magnetic field becomes increasingly helical with increasing torque. The helical magnetization resulting from the applied torque includes an axial component in the direction of the axis of the shaft
Implementation Method 3
A magnetic sensor located proximate the shaft may detect the axial component and provide an output indicative of the level of torque applied to the shaft
Data Source
AI summary
A torque sensor includes a shaft and a magnetic sensor. The shaft may have at least one active region having an elliptical magnetization. The magnetic sensor may be configured to sense a magnetic field about the shaft, where the magnetic field is representative of a torque applied to the shaft. The elliptical magnetization may have a nonzero axial component directed along a center line axis of said shaft at zero torque.