Speed Reducer With Differing Bearing Sizes For Miniaturization
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Solution Overview
Problem
Existing reducer-in-wheel systems face challenges in miniaturization due to the identical diameter of bearings and the structural constraints within the wheel assembly, making it difficult to further reduce the size of the wheel assembly and the object being driven.
Innovation Solution
A speed reducer design featuring a sun gear, planetary gears, and an internal gear with a smaller second bearing positioned closer to the output side, allowing for a reduction in the radial size of the output part and enabling miniaturization of the driven object, while maintaining stability and torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If identical diameter bearings are used in the speed reducer, then the structural symmetry and manufacturing simplicity are improved, but the miniaturization capability of the wheel assembly is worsened
Solution Approach 1:
The patent applies local quality by making the two bearings have different radial sizes according to their specific functional requirements. The first bearing (closer to input side) has a larger radial size to handle higher radial loads from planetary gears, while the second bearing (closer to output side) has a smaller radial size since it primarily supports axial loads. This localized differentiation optimizes each bearing's size for its specific position and load conditions, enabling miniaturization of the overall wheel assembly while maintaining manufacturing feasibility.
2Volume of moving object
If the radial size of bearings is reduced for miniaturization, then the wheel assembly size is improved, but the supporting ability and reliability are worsened
Solution Approach 1:
The patent ensures reliability through local quality optimization where each bearing's radial size is specifically tailored to its load conditions. The first bearing maintains a larger radial size to reliably support heavy radial loads from planetary gear engagement, while the second bearing is optimized with appropriate radial size for its axial load support function. This localized optimization ensures that each bearing has sufficient supporting ability for its specific operational requirements while enabling overall miniaturization.
Solution Approach 2:
The patent inverts the conventional approach by not using identical bearings throughout, but rather differentiating bearing sizes based on functional requirements. Instead of applying a uniform bearing size solution, the invention reverses to a differentiated approach where bearing dimensions are specifically matched to local load conditions, thereby maintaining reliability while achieving miniaturization.
3Volume of moving object
If the output part diameter is reduced for miniaturization, then the wheel assembly size is improved, but the torque transmission capability is worsened
Solution Approach 1:
The patent applies local quality by optimizing the output part structure with differentiated bearing sizes that correspond to different functional zones. The first bearing position is designed with larger radial size to handle high radial loads during torque transmission, while the second bearing position uses smaller radial size appropriate for axial support. This localized optimization allows the output part to maintain adequate torque transmission capability at critical load points while reducing overall diameter for miniaturization.
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 effectively miniaturizes the wheel assembly and the object being driven by reducing the diameter of the output part, facilitating smaller wheel sizes and enhancing the miniaturization of the speed reducer without compromising supporting ability or torque transmission.
Implementation Method 1
a planetary gear mechanism having a sun gear and a planetary gear, the planetary gear mechanism being configured to transmit power
Implementation Method 2
converting rotational motion about a rotation axis extending between an input side and an output side, at a first rotation speed into rotational motion at a second rotation speed being lower than the first rotation speed
Implementation Method 3
a first bearing that is interposed between the fixed part and the output part at a position closer to the input side with respect to the plurality of planetary gears; and a second bearing that is interposed between the fixed part and the output part at a position closer to the output side with respect to the plurality of planetary gears
Data Source
AI summary
A speed reducer includes a sun gear, planetary gears, a fixed part, an output part, a first bearing, and a second bearing. The sun gear rotates relative to the fixed part at a first rotation speed. The planetary gears are disposed around the sun gear to engage with the sun gear. The output part includes an annular internal gear engaging with the planetary gears. The output part rotates relative to the fixed part at a second rotation speed lower than the first rotation speed. The first bearing is interposed between the fixed part and the output part at a position closer to an input side with respect to the planetary gears. The second bearing is interposed between the fixed part and the output part at a position closer to an output side with respect to the planetary gears. The second bearing is smaller in radial size than the first bearing.