Mid-Mounted Motor Planetary Gear Layout for High Torque
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Solution Overview
Problem
Existing mid-mounted motors in power-assisted bicycles face challenges in balancing an appropriate transmission ratio with a compact size, leading to issues with size, weight, and output torque.
Innovation Solution
A mid-mounted motor design incorporating a sun gear, planetary gear structure, and ring gear structure, with a first transmission component that transmits power through gear meshing, enabling a high transmission ratio within a limited space, thus balancing size and torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a conventional mid-mounted motor design is used, then the structure is simple, but the transmission ratio is insufficient and the size is too large
Solution Approach 1:
The patent employs a planetary gear structure where the sun gear, planetary gears, and ring gear are nested within each other in a compact arrangement. The planetary gears are positioned between the sun gear and ring gear, creating a nested configuration that achieves high transmission ratio (up to 20:1) within a limited radial space, directly resolving the contradiction between compact size and high transmission ratio
Solution Approach 2:
The patent transitions from conventional linear gear arrangements to a multi-dimensional planetary gear configuration. By arranging gears in concentric circles with different diameters (sun gear at center, planetary gears in intermediate orbit, ring gear as outer boundary), the design utilizes radial and angular dimensions simultaneously to achieve compact packaging while maintaining high transmission ratio
2Weight of moving object
If the motor size is reduced, then the weight decreases, but the output torque becomes insufficient
Solution Approach 1:
The nested planetary gear structure allows the motor to maintain a compact, lightweight form factor while achieving high transmission ratio. The concentric arrangement of sun gear, planetary gears, and ring gear enables torque multiplication without increasing the overall motor volume or weight, thus resolving the contradiction between weight reduction and torque maintenance
Solution Approach 2:
The patent changes the transmission ratio parameter through careful selection of gear tooth counts and diameters. By optimizing the ratio between sun gear, planetary gears, and ring gear, the system achieves high torque output (up to 1000 N·m) from a compact motor design, transforming the parameter relationship between size, weight, and torque
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
The design achieves a higher transmission ratio, smaller size, and lighter weight, enhancing integration and user experience while providing greater output torque.
Implementation Method 1
the sun gear meshes with the planetary gear structure, and the planetary gear structure meshes with at least a portion of the ring gear structure
Implementation Method 2
enabling a high transmission ratio within a limited space
Implementation Method 3
the first transmission component transmits, by way of gear meshing transmission, a power transmitted to the transmission mechanism from the driving mechanism
Data Source
AI summary
A mid-mounted motor is provided, includes a driving mechanism, a transmission mechanism, and an output mechanism. The transmission mechanism includes a sun gear, a planetary gear structure, and a ring gear structure. The sun gear is connected in transmission with the driving mechanism and meshes with the planetary gear structure, and the planetary gear structure meshes with at least part of the ring gear structure; the output mechanism includes a first transmission component, which is arranged on the transmission mechanism. The first transmission component transmits the power delivered by the driving mechanism to the transmission mechanism to other components through a gear meshing transmission mode. A power-assisted bicycle is also provided.