Crank Transmission Torque Sensing via Torsion Angle Offset
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Solution Overview
Problem
Existing crank transmissions lack an effective method to detect the torque applied via a crankshaft, which is crucial for optimizing power generation, gear shifting, and safety features like coaster brakes.
Innovation Solution
A crank transmission system that incorporates a torsion element with an angular offset mechanism, coupled with a sensor system using a magnetic flux transducer and Hall sensors, to detect the torque-dependent angular offset and determine the magnitude and direction of the torque applied.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sensor arrangement with torsion element and magnetic sensor is implemented in the crank transmission, then torque and angle of rotation detection capability is improved, but device complexity increases
Solution Approach 1:
The patent combines the torsion element with the crankshaft into an integrated assembly, where the torsion element is directly mounted on the crankshaft. This merging reduces the number of separate components and simplifies the overall structure while maintaining torque detection capability through the angular offset between the torsion element and crankshaft.
Solution Approach 2:
The crankshaft serves multiple functions: it acts as both the driving component for power transmission and as the mounting structure for the torsion element and magnetic sensor. This multi-functionality reduces the need for separate detection装置, thereby lowering device complexity while enabling torque measurement.
2Measurement precision
If a torsion element is added to the crank transmission for torque detection, then torque measurement capability is improved, but the device occupies more space
Solution Approach 1:
The torsion element is positioned within the structural space of the crankshaft assembly, nesting the detection component within the existing mechanical structure. This allows the torsion element to be accommodated without significantly increasing the external dimensions of the crank transmission.
Solution Approach 2:
The torsion element utilizes the axial dimension of the crankshaft, extending along the axis rather than occupying radial or lateral space. This dimensional arrangement allows torque detection functionality to be added without increasing the overall footprint of the crank transmission mechanism.
3Measurement precision
If angular offset detection is implemented to determine torque direction, then measurement capability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The magnetic sensor acts as an intermediary that converts the mechanical angular offset into an electrical signal. This intermediary approach allows for precise measurement of small angular offsets without requiring extremely tight mechanical tolerances, as the magnetic field can detect subtle positional changes between the torsion element and crankshaft.
Solution Approach 2:
The system measures changes in angular position rather than absolute positions, and uses the magnetic sensor to amplify these small angular changes into measurable electrical signals. This parameter transformation approach reduces the impact of manufacturing tolerances on 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 solution enables robust, cost-effective, and space-efficient detection of torque magnitude and direction, facilitating data acquisition for power optimization, automatic gear shifting, and enhanced safety features.
Implementation Method 1
the torsion element is elastically deformable at least in certain areas, i.e. it can be deformed elastically against a restoring torque
Implementation Method 2
a transducer unit is provided for converting the angular offset into a change in a magnetic flux
Implementation Method 3
a magnetic field-sensitive sensor is provided for detecting this change
Data Source
AI summary
A crank transmission having a crankshaft for connection to at least one foot or hand crank and at least one gear wheel driven by means of the crankshaft (5) is proposed. A coupling unit is provided between the crankshaft and the gear wheel. Under load, the coupling unit has at least temporarily an angular offset between a crank-side receiving region and an output region connected to the gear wheel for receiving and outputting the torque generated via the crank.