Long Narrow E-Bike Motor Torque via Outer Rotor
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Solution Overview
Problem
Conventional power-driving motors for electric bikes, especially those fitted in the frame's down tube, suffer from insufficient torque output due to their small diameter, leading to reduced power supply and increased weight and design complexity when attempting to enhance length.
Innovation Solution
A power-driving motor design where the rotor is positioned outside the stator, with a motor spindle having sections of varying diameters and clearances, allowing the motor to be longer than wide, thus increasing the distance between the rotor and spindle to enhance torque output by up to 50%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the power-driving motor is designed with small diameter to fit in the down tube, then the motor can be installed in the bike frame, but the torque output is insufficient
Solution Approach 1:
The patent transitions from a conventional short-wide motor configuration to a long-narrow configuration by extending the motor length along the down tube axis. This dimensional change allows the motor to fit within the down tube while achieving sufficient torque through increased active length of the stator and rotor components.
Solution Approach 2:
The motor components are nested within the down tube structure, with the stator and rotor arranged concentrically around the motor spindle. The entire motor assembly is contained within the down tube, utilizing the available space efficiently to achieve both compact installation and adequate torque output.
2Force
If the length of the power-driving motor is increased to improve torque output, then the torque supply is sufficient, but the weight and design cost increase and the design becomes difficult
Solution Approach 1:
The motor spindle is divided into sections with different diameters, and the bearing arrangement is segmented into multiple positions along the motor length. This segmentation allows for optimized torque transmission while managing structural complexity through modular design elements.
Solution Approach 2:
Different sections of the motor have different structural characteristics - the motor spindle has varying diameters at different locations, and bearings are positioned at specific locations where they are most needed. This local optimization achieves sufficient torque output without uniformly increasing complexity throughout the entire motor structure.
3Force
If the length of the power-driving motor is increased to improve torque output, then the torque supply is sufficient, but the weight is added
Solution Approach 1:
The patent changes the geometric parameters of the motor, specifically the length-to-diameter ratio, by extending the motor length while maintaining a compact diameter. This parameter change allows the motor to achieve sufficient torque through increased active length rather than increased mass or diameter.
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 effectively increases torque output by up to 50% compared to conventional motors, addressing the issue of insufficient power while maintaining a compact and cost-efficient configuration.
Implementation Method 1
the first section extends through and is connected to a first bearing corresponding to the mounting portion and the second section extends through and is connected to at least one second bearing provided in the mounting holder
Data Source
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AI summary
A power-driving motor (10) for power-driving bike is provided, of which the length is obviously larger than its width. A rotor (14) of the power-driving motor (10) is provided at the outside of the stator (12) so as to make the distance from the rotor (14) to the motor spindle (13) increase; namely, a torque increases and then an arm increases, thereby, making the motor spindle (13) supply a higher output torque to the connected driving unit when the rotor (14) rotates. The motor (10), based on the length of a conventional power-driving motor (10), may supply a higher output torque to solve the defect of a conventional motor implemented with an inner rotor (14) of which the output torque is insufficient.