Hanger Bearing Torque Sensor for Stable Shaft-Sensor Gaps
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Solution Overview
Problem
Existing torque sensing systems face inaccuracies due to large gaps between sensors and rotating shafts, which are costly, complex, and pose integration challenges, especially in applications like aircraft design, where conventional solutions like stiffening the drivetrain or using magnetoelastic sensors fail to provide accurate twist measurement and multi-axis shaft motion.
Innovation Solution
A torque sensing architecture that minimizes the gap between sensors and the shaft by using hanger bearings to suspend the drivetrain compliantly, allowing the sensor to be rigidly attached to a bearing frame that moves in unison with the shaft, reducing the radial distance to approximately 0.02 inches, and employs variable reluctance sensors to measure torsional deformation accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sensor is positioned far from the shaft to avoid contact, then the shaft does not strike the sensor during operation, but the measurement accuracy deteriorates due to large gap variations
Solution Approach 1:
The bearing is designed to be compliantly mounted rather than rigidly fixed, allowing it to dynamically follow the shaft's radial movements. This dynamic adaptation enables the sensor to maintain a small, consistent gap from the shaft surface despite shaft displacement, simultaneously ensuring reliable operation and accurate measurement.
Solution Approach 2:
The compliant mounting acts as an intermediary between the fixed structure and the sensor assembly. It transmits the shaft's radial movements to the sensor while maintaining a controlled gap, effectively mediating between the need for close proximity (for accuracy) and the need to avoid contact (for reliability).
2Measurement precision
If the drivetrain is stiffened to reduce the gap between sensor and shaft, then measurement accuracy improves, but the device complexity and integration difficulty increase
Solution Approach 1:
The invention extracts the gap-reduction function from the drivetrain structure itself and relocates it to the sensor mounting system. Instead of modifying the drivetrain to reduce gaps, the compliant mounting independently manages the gap through its own elastic properties, simplifying the overall system.
Solution Approach 2:
The rigid mechanical connection (stiffening the drivetrain) is replaced with an elastic/compliant mounting. This substitution achieves gap reduction through material elasticity rather than structural reinforcement, reducing device complexity while maintaining measurement precision.
3Ease of manufacture
If conventional sensors are used with large gaps, then integration is easier, but the sensor amplitude and phase change dramatically over gap variations requiring complex compensation algorithms
Solution Approach 1:
The compliant mounting dynamically adapts to shaft position, maintaining a small, consistent gap throughout operation. This dynamic adjustment eliminates the need for complex signal processing compensation algorithms, as the gap variation is minimized by the mechanical system itself rather than requiring software correction.
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 approach provides highly accurate torque and speed measurement with minimal invasiveness, reducing errors associated with large gaps and enabling precise twist measurement even with small shaft motions, thus improving accuracy and integration feasibility.
Implementation Method 1
Variable reluctance (VR) sensors are employed to measure changes in the timing of pulses produced by the passage of the ferrous targets
Implementation Method 2
at least one sensor configured to measure a torque transmitted through the shaft
Implementation Method 3
the hanger bearings, as well as the drivetrain components to which the hanger bearings are attached, are capable of movement relative to the fixed structure
Data Source
AI summary
Torque sensing devices, systems, and methods are capable of measuring and/or determining a torque being transmitted through a shaft by measuring the torsional deformation of the shaft over a short length thereof. Such devices, systems, and devices have a sensor positioned adjacent to the outer surface of the shaft as it rotates, the sensor being positioned to maintain a substantially constant distance between the sensor and the outer surface of the shaft. The sensors may be variable reluctance (VR) sensors rigidly attached to a frame mounted on a bearing (e.g., a hanger bearing), which is mounted on the shaft, such that relative radial motion between the shaft and the VR sensor is minimized (e.g., so that they move in unison). Reducing this amount of motion results in a more accurate torque measurement.