Torque Measurement in Gearbox Shaft Using Encoder Consoles
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Solution Overview
Problem
Mechanical torque measurement in agricultural machinery, such as twin-disk fertilizer spreaders, faces inaccuracies due to short torsion angles and variable distances between incremental encoders and pulse pickups, leading to imprecise fertilizer mass flow measurements, especially under high starting torques and vibrations.
Innovation Solution
Mounting incremental encoders in consoles connected to the transmission housing, ensuring a constant distance between encoders and pulse pickups, allowing for maximum torsion angle measurement and shaft movement without affecting the encoder-pickup distance, using a transmission sleeve to absorb torsional angular position and allowing axial movement of the shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the diameter of the gear shaft is reduced to increase the torsion angle, then the torsion angle increases, but the shaft vibrates under high starting torques leading to inaccurate measurements
Solution Approach 1:
The measurement system is segmented into two independent parts: the shaft (which experiences torsion and vibration) and the encoder assembly (which remains stable). By mounting encoders on separate consoles connected to the housing rather than directly on the shaft, the measurement function is separated from the vibrating component, allowing accurate measurement without shaft vibration problems.
Solution Approach 2:
Consoles act as intermediary elements between the shaft and the encoders. These consoles are firmly connected to the housing and provide a stable mounting platform for the encoders, mediating the connection between the rotating shaft and the measurement devices while filtering out vibrations.
2Device complexity
If incremental encoders are mounted close to each other on the shaft, then the device complexity is reduced, but the torsion angle measurement accuracy decreases
Solution Approach 1:
Instead of increasing the axial distance between encoders along the shaft (one dimension), the solution moves the encoders to different radial positions around the shaft using consoles extending from the housing. This allows maximum measurement baseline in the radial dimension while keeping the axial arrangement simple.
3Device complexity
If the distance between the encoder and pickup is allowed to vary with shaft movement, then the device complexity is reduced, but the measurement accuracy decreases
Solution Approach 1:
The encoder assembly is extracted from direct shaft mounting and placed on separate consoles connected to the housing. This extraction allows the encoder-pickup distance to be maintained constant relative to the housing while the shaft moves, separating the measurement reference frame from the moving shaft.
Solution Approach 2:
The consoles serve multiple functions: they provide structural support for the encoders, maintain constant encoder-pickup distances, allow shaft movement, and provide firm connection to the housing. This multi-functionality simplifies the overall mounting system while maintaining measurement accuracy.
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 design provides precise and cost-effective torque measurement by maximizing the torsion angle detection, ensuring accurate fertilizer mass flow measurement with reduced common-mode interference and minimal offset changes, using only three incremental encoders and pulse pickups.
Implementation Method 1
incremental encoders are arranged in a rotationally fixed manner, which interact with pulse pickups
Data Source
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AI summary
The gear box has a drive unit (2) and an output unit that are connected over a shaft (8). A torque measuring device measures torque of the shaft and includes an incremental transmitter rotatably fixed with the shaft and an impulse transducer fixedly arranged in a circulation region of the device for measuring a torsion angle. The incremental transmitter is supported in a bracket, which is firmly connected with a gear housing (1). The incremental transmitter is rotatably arranged close to the drive unit and near an output of the shaft. The gear box includes a transmission case that is made of steel or plastic.