Hanger Bearing-Mounted Torque Sensor for Constant Shaft Gaps
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Solution Overview
Problem
Existing torque sensing systems face challenges with accuracy and complexity due to large gaps between sensors and rotating shafts, leading to inaccuracy and integration issues, especially in applications like aircraft design.
Innovation Solution
A torque sensing architecture that minimizes the gap between sensors and the shaft by mounting sensors to a frame rigidly attached to a bearing, allowing for precise measurement of torque and speed in flexible drivetrains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a large gap is maintained between the sensor and the rotating shaft, then the shaft can move freely without striking the sensor, but measurement accuracy deteriorates due to the predominant gap factor
Solution Approach 1:
The bearing is made movable relative to the fixed structure, allowing it to dynamically follow the shaft's radial deflection. This dynamic adaptation enables the sensor mounted on the bearing to maintain a constant small gap with the rotating shaft while the bearing itself moves freely relative to the fixed structure, resolving the contradiction between measurement accuracy and shaft movement freedom
Solution Approach 2:
The bearing serves as an intermediary component between the fixed structure and the rotating shaft. It is fixed to the sensor but movable relative to the fixed structure, allowing the sensor to closely follow the shaft's motion without being rigidly constrained to the fixed structure. This intermediary enables both high measurement accuracy and shaft movement freedom
2Measurement precision
If the drivetrain and structure are stiffened to reduce the gap between sensors and shaft, then measurement accuracy improves, but device complexity and integration challenges increase
Solution Approach 1:
The bearing acts as a movable intermediary that eliminates the need to stiffen the entire drivetrain structure. By allowing the bearing (and mounted sensor) to move relative to the fixed structure, the system achieves small sensor-shaft gaps without requiring complex structural stiffening, thus improving accuracy while avoiding increased device complexity
Solution Approach 2:
The system changes the state of the bearing from fixed to movable relative to the fixed structure. This parameter change allows the sensor to maintain a constant small gap with the shaft through the bearing's motion, achieving high measurement accuracy without modifying the structural stiffness or increasing device complexity
3Measurement precision
If multiple sensors are disposed across multiple measurement planes, then twist accuracy and multi-axis motion measurement improve, but device complexity and integration challenges increase
Solution Approach 1:
Multiple sensing functions are merged into a single sensor platform mounted on the movable bearing. The bearing supports the sensor assembly that can measure twist and potentially multi-axis motions, combining what would otherwise require multiple distributed sensors into one integrated unit, thereby improving measurement capability while reducing device complexity
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 highly accurate twist measurement and multi-axis shaft motion with a lightweight and minimally invasive approach, significantly reducing errors associated with large gaps and improving integration in complex systems.
Implementation Method 1
the bearing being substantially incapable of radial movement relative to the drivetrain component to which it is attached
Implementation Method 2
Variable reluctance (VR) sensors are employed to measure changes in the timing of pulses produced by the passage of the ferrous targets
Implementation Method 3
a compliant mount configured to attach the frame to a fixed structure, such that the frame is configured to move substantially in unison with the shaft, relative to the fixed structure, in at least two dimensions
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.