Freewheel Isolates Magnetostrictive Torque Sensor from Reverse Loads
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Solution Overview
Problem
Existing magnetostrictive torque sensors experience increased hysteresis and offset shifts when torques act in both directions, reducing accuracy, particularly in mechanically driven torque-controlled systems like fertilizer spreaders.
Innovation Solution
Incorporating a freewheel between the drive and torque module to prevent torque transmission in the opposite direction, ensuring the torque module only measures torques in the drive direction, thereby reducing hysteresis and offset shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If magnetostrictive torque sensors are used to detect torque in both directions, then the sensor can measure bidirectional torque, but hysteresis increases considerably and offset shifts occur, reducing sensor accuracy
Solution Approach 1:
A freewheel mechanism is introduced as an intermediary between the drive shaft and the torque sensor. This freewheel allows the sensor to measure torque in the drive direction while blocking reverse torques from reaching the sensor, thus protecting the sensor from hysteresis and offset shifts caused by bidirectional loading
2Reliability
If PTO brakes are installed in the tractor to control torque, then torque control is improved, but high negative torques occur after PTO shutdown that increase hysteresis and reduce measurement accuracy
Solution Approach 1:
The freewheel acts as a protective intermediary that isolates the torque sensor from harmful reverse torques generated by PTO brakes during shutdown. By blocking these negative torques, the sensor maintains measurement accuracy while the PTO brake system continues to provide reliable torque control
3Measurement precision
If a freewheel is arranged between the drive and torque module to prevent reverse torque transmission, then sensor accuracy is improved by reducing hysteresis and offset shifts, but device complexity increases
Solution Approach 1:
The freewheel is a relatively simple mechanical component that can be integrated into the existing drive train without major redesign. It provides the necessary protection for the torque sensor while adding minimal complexity to the overall system
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 arrangement enhances long-term sensor accuracy by isolating the torque module from counter-directional torques, improving the precision of magnetostrictive torque measurements.
Implementation Method 1
If a torque is now applied to the shaft and the ring connected to it, the magnetostrictive ring generates a magnetic field outside the ring, which changes with the applied torque
Implementation Method 2
A magnetic field sensor arranged near the ring detects the magnitude of this magnetic field and generates a corresponding output signal
Data Source
Figure 1
AI summary
The invention relates to an assembly, comprising a rotatably supported shaft (03), a drive for driving the shaft (03) in a driving direction, and a torque module (09) for magnetostrictively sensing the torque of the shaft (03). The assembly according to the invention is characterized in that a freewheel (10) is arranged between the drive and the torque module (09), which freewheel serves to transmit torques in the driving direction and to block the transmission of torques against the driving direction. The invention further relates to a drive train (01) of a broadcast spreader, comprising at least one spreading disk fastened to a shaft (03) for conjoint rotation, a drive for rotationally driving the shaft (03) in a driving direction, and a torque module (09) for magnetostrictively sensing the torque of the shaft (03). A freewheel (10) is arranged between the drive and the torque module (09), which freewheel serves to transmit torques in the driving direction and to block the transmission of torques against the driving direction.