Electric Bicycle Motor Torque Sensor Integration
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Solution Overview
Problem
The existing freehub torque speed sensing device for electric bicycles has a long lead wire extending from the torque sensor to the outside, which complicates the routing and assembly of the system.
Innovation Solution
A motor design that integrates a torque sensor with a rotor and stator, featuring a hub that accommodates the rotor and stator, a circuit board between the rotor and torque sensor, and a first fixed shaft supporting the torque sensor, with sensor and signal wires efficiently routed within the hub to reduce external exposure and simplify assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the torque sensor is positioned on the axis opposite to the sprocket, then the torque sensor can be integrated with the rotor and stator, but the lead wire becomes long and routing becomes complicated
Solution Approach 1:
The torque sensor is repositioned from the conventional axial position to a radial position on the hub, changing the spatial dimension of sensor placement. This dimensional shift allows the sensor to be integrated with the rotor-stator assembly while keeping the lead wire route short and direct, as the wire can now extend radially outward from the hub rather than axially along the shaft.
2Adaptability or versatility
If the lead wire extends from the torque sensor to the outside, then the sensor can be positioned away from the rotor, but the wire routing becomes complicated and assembly becomes difficult
Solution Approach 1:
The torque sensor is merged with the rotor-stator assembly by positioning it on the hub that accommodates both components. This merging eliminates the need for separate sensor mounting structures and simplifies the lead wire routing, as the wire can now be routed directly from the hub to the external circuit without navigating around separate sensor and motor components.
3Length of stationary object
If the torque sensor is integrated with rotor and stator in the hub, then the exposed wire length is reduced, but the hub structure becomes more complex
Solution Approach 1:
The hub is designed to serve multiple functions: it accommodates the rotor, supports the stator, positions the torque sensor, and provides a mounting structure for the lead wire. This multi-functionality reduces the need for separate structural components, thereby minimizing exposed wire length without proportionally increasing overall structural complexity.
Data Source
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AI summary
A motor (10) includes a rotor (100) having a rotor shaft (160) extending along a virtual central axis, the rotor (100) rotating about the rotor shaft (160); a stator (200) positioned radially outside with respect to the rotor (100); a hub (300) that accommodates the rotor (100) and the stator (200) and rotates with rotation of the rotor (100); a torque sensor (500) positioned on an axial one side with respect to the rotor (100) and detects torque of the rotor shaft (160); a circuit board (400) accommodated in the hub (300) and positioned between the rotor (100) and the torque sensor (500); a sensor wire (550) electrically connecting the torque sensor (500) and the circuit board (400); a signal wire (450) electrically connected to an external circuit on a surface on an axial one side of the circuit board (400); and a first fixed shaft (610) positioned on an axial one side with respect to the rotor shaft (160).