E-Bike Power Transmission Unit With Overlapping Torque Detection
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Solution Overview
Problem
Existing power transmission units for electric bicycles face challenges in effectively utilizing space due to the separate placement of torque sensors and rotation detectors, leading to complex interconnections and increased size.
Innovation Solution
A power transmission unit design where the torque detection unit and detection target overlap when viewed perpendicularly to the rotational axis, allowing for closer arrangement and simplified interconnection, along with a transmission member that transmits rotational power from the input shaft to the output structure, optimizing space usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the torque sensor and rotation detector are arranged at separate positions along the axis of the crankshafts, then the detection functions are fulfilled, but the interconnection becomes complicated and space utilization is reduced
Solution Approach 1:
The torque detection unit and rotation detection unit are merged into a single integrated detection system. The torque detection unit includes both a magnetostriction generator unit and a coil for torque detection, while the rotation detector uses a detection target with detection marks. By integrating these detection functions into one unit and arranging them to overlap when viewed from the axial direction, the patent simplifies interconnection while maintaining reliable detection of both torque and rotation.
Solution Approach 2:
The patent transitions from arranging detection units along the axial direction (one-dimensional arrangement) to arranging them in overlapping positions when viewed from the axial direction (two-dimensional spatial arrangement). This dimensional change allows the torque detection unit and rotation detector to be positioned closer together, reducing interconnection complexity while maintaining detection reliability.
2Reliability
If the torque sensor and rotation detector are arranged at separate positions, then the detection functions are fulfilled, but the space utilization inside the unit is reduced
Solution Approach 1:
The integration of torque detection and rotation detection functions into a single unit allows both detection mechanisms to share the same spatial envelope. The torque detection unit and rotation detector are positioned to overlap when viewed from the axial direction, maximizing space utilization within the limited volume of the power transmission unit while ensuring both detection functions operate reliably.
3Volume of moving object
If the detection units are arranged closer together, then space utilization is improved, but the interconnection becomes more complex
Solution Approach 1:
The patent resolves the conflict between close arrangement and interconnection complexity by changing the spatial arrangement from linear (along the axis) to overlapping (when viewed from the axis). This allows the detection units to be positioned close together for better space utilization while the overlapping arrangement naturally simplifies the interconnection paths between components.
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 enhances space utilization within the unit, simplifies connections, and reduces the overall size of the power transmission system while maintaining accurate torque detection and efficient power transmission.
Implementation Method 1
The torque sensor is implemented as a magnetostrictive sensor, which includes a magnetostriction generator unit formed on an outer peripheral surface of the human driving force transmission body and a coil wound around its outer periphery
Data Source
AI summary
A power transmission unit for electric bicycles includes an input structure, an output structure, a torque detection unit, a detection target, and a detection unit. The input structure includes an input shaft. The input shaft is caused to rotate by external force transmitted thereto. The input structure rotates along with the input shaft. The output structure outputs rotational power by rotating along with the input structure. The torque detection unit is provided on an outer periphery of the input structure. The detection target rotates either along with, or while interlocking with, the input structure. The detection unit detects a rotational state of the detection target. At least part of the torque detection unit and at least part of the detection target overlap with each other when viewed perpendicularly to a rotational axis of the input structure.