In-Wheel Power Transmission Layout for High Reduction Ratios
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Solution Overview
Problem
Indirect driving-type in-wheel systems face limitations in achieving large speed reduction ratios due to the volume occupied by decelerators, which increases the size of the in-wheel system, especially when multiple decelerators are used.
Innovation Solution
A power transmission device with two decelerators, where the first decelerator is partially inserted into the rotary shaft and coupled thereto, and the second decelerator is coupled to the first decelerator, featuring planetary gears and helical gear regions with opposite helix angles to minimize space and enhance sealability and modularization, allowing for efficient speed reduction without excessive size increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If two or more decelerators are provided in the in-wheel system to achieve a large speed reduction ratio, then the speed reduction ratio increases, but the size of the in-wheel system in the width direction becomes excessively increased
Solution Approach 1:
The first decelerator is partially inserted into the rotary shaft, and the second decelerator is coupled to the first decelerator, creating a nested arrangement where decelerators are positioned within the width of the wheel bearing rather than extending outward. This nesting principle allows multiple decelerators to be accommodated without excessively increasing the width of the in-wheel system.
Solution Approach 2:
The patent transitions from a conventional arrangement where decelerators extend in the width direction to a configuration where decelerators are arranged primarily in the axial direction (inserted into the rotary shaft). This dimensional change allows the speed reduction mechanism to achieve large reduction ratios without increasing the width of the in-wheel system.
2Force
If a decelerator is mounted to increase output torque, then torque increases, but the volume occupied by the decelerator limits the speed reduction ratio that can be achieved
Solution Approach 1:
The decelerators are nested within the rotary shaft and wheel bearing structure, utilizing the internal space rather than occupying additional external volume. This allows the system to achieve high torque multiplication without the decelerator volume becoming a limiting factor for the speed reduction ratio.
3Volume of moving object
If the first decelerator is partially inserted into the rotary shaft and coupled thereto, then space is minimized and sealability is enhanced, but the structural complexity increases
Solution Approach 1:
The power transmission device is segmented into modular components: the first decelerator inserted into the rotary shaft, the second decelerator coupled to the first, and the wheel bearing accommodating both. This segmentation allows each component to be optimized independently while maintaining overall compactness and sealability.
Solution Approach 2:
The first decelerator is merged with the rotary shaft through partial insertion and coupling, creating an integrated structure that minimizes the overall space occupied. This merging reduces the number of separate external components and enhances sealability by reducing interfaces with the external environment.
Data Source
AI summary
A power transmission device include a motor including a rotary shaft, a first decelerator, coupled to the rotary shaft of the motor, configured to receive power from the rotary shaft, a second decelerator, coupled to the first decelerator, configured to receive the power from the first decelerator, and a wheel bearing coupled to one side of the second decelerator. A portion of the first decelerator is configured to insert into the rotary shaft and couple thereto.