Hub Motor Transmission Layout for Higher Torque in Light Vehicles
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Solution Overview
Problem
Existing hub motors for vehicles such as scooters and bicycles are often heavy, bulky, and expensive due to custom and large electric motor arrangements, which hinder their widespread adoption in lightweight vehicles like children's vehicles.
Innovation Solution
Incorporating a transmission assembly with a larger ring gear and a double planetary gear configuration, where a first gear is positioned closer to the rotational axis and a second gear is farther away, allowing for a larger gear ratio and increased torque without increasing the motor's size or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a larger ring gear is used to increase torque, then the gear ratio increases and torque increases, but the device complexity and size increase
Solution Approach 1:
The patent employs a planetary gear system where a sun gear is positioned at the center, surrounded by planet gears that rotate around it, all contained within an annular ring gear. This nested configuration allows multiple gears to occupy the same spatial envelope, achieving a large effective gear ratio without increasing the overall footprint of the transmission assembly. The planet gears are mounted on a carrier that rotates around the sun gear, creating a compact multi-stage reduction system.
Solution Approach 2:
The planetary gear arrangement transforms a linear sequence of gears into a radial, two-dimensional configuration. By arranging gears in concentric circles around a central axis rather than in a straight line, the system achieves a larger effective gear ratio without increasing the axial length or radial footprint, thereby reducing device complexity while maintaining high torque output.
2Power
If custom and large electric motor arrangements are used, then torque and power increase, but weight and cost increase
Solution Approach 1:
The patent replaces a mechanically complex motor arrangement with a simpler motor coupled to a planetary gear transmission system. Instead of using a large, heavy motor to directly produce high torque, the system uses a smaller, lighter motor that drives a compact planetary gear set. This mechanical substitution allows the same or higher torque output with reduced motor weight and overall hub motor assembly weight.
3Force
If a larger ring gear is used to increase torque, then the gear ratio increases and torque increases, but the hub motor becomes bulky
Solution Approach 1:
The planetary gear system nests multiple gears (sun gear, planet gears, ring gear) within each other in a compact radial arrangement. This nesting allows the transmission assembly to achieve a large effective gear ratio without requiring a proportionally large ring gear diameter, thereby reducing the overall volume of the hub motor while maintaining high torque capability.
Solution Approach 2:
By transitioning from a linear gear train to a radial planetary configuration, the system packs more gear reduction into a smaller volumetric envelope. The concentric arrangement of gears around a central axis maximizes the use of two-dimensional space, achieving high gear ratios without increasing the axial or radial dimensions of the hub motor assembly.
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 solution provides enhanced torque and efficiency at a reasonable cost, enabling improved acceleration and climbing capabilities in lightweight vehicles.
Implementation Method 1
The transmission assembly may include a first gear (e.g., planetary gear) positioned a first distance away from a rotational axis of the hub motor arrangement and a second gear (e.g., idler gear) positioned a second distance, greater than the first distance, away from the rotational axis of the hub motor arrangement. The motor can drive the first gear, the first gear can drive the second gear, and the second gear can drive the ring gear which drives a rotation of a housing and/or tire of the hub motor arrangement to propel a vehicle incorporating the hub motor arrangement.
Implementation Method 2
The hub motor arrangement may include a plurality of gears that can include a first gear and a second gear. The first gear can include a first axis of rotation a first distance away from the axis of rotation of the housing. The second gear can include a second axis of rotation a second distance away from the axis of rotation of the housing.
Data Source
AI summary
Various hub motor arrangements, systems, and methods are disclosed. The hub motor arrangement may include a transmission assembly to provide increased torque. The transmission assembly may include a motor gear, a planetary gear, an idler gear, and a ring gear. The idler gear may be positioned farther away from an axis of rotation of the hub motor arrangement compared to the planetary gear. The motor gear may drive the planetary gear, the planetary gear may drive the idler gear, and idler gear may drive the ring gear. The rotation of the ring gear may rotate a housing of the hub motor arrangement to propel a vehicle incorporating the hub motor arrangement.