Planetary Speed Reducer Carrier Layout for Higher Rigidity
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Solution Overview
Problem
Conventional planetary gear reducers lack sufficient rigidity due to column portions being spaced apart in the circumferential direction, which limits their ability to effectively receive moment loads.
Innovation Solution
The design includes a carrier positioned between adjacent planetary shafts in the circumferential direction, with column portions extending between these shafts and connecting portions that are tangent to the addendum circle diameter of the second planetary gear, enhancing the carrier's ability to receive moment loads and increase rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If column portions are spaced apart in the circumferential direction to support planetary shafts, then the structure is simpler and easier to manufacture, but the rigidity decreases and the ability to receive moment loads is insufficient
Solution Approach 1:
The column portion is extended not only in the radial direction but also in the circumferential direction, creating a three-dimensional structure that spans between planetary shafts. This dimensional extension allows the column portion to effectively receive moment loads in multiple directions while maintaining structural simplicity.
Solution Approach 2:
The column portion is positioned within the region bounded by tangent lines to the addendum circle diameter of the second planetary gear, nesting the structural reinforcement within the existing gear geometry. This allows the carrier to receive moment loads without interfering with the meshing operation of the planetary gears.
2Strength
If column portions are positioned to maximize moment load reception, then rigidity increases, but the space for planetary gear operation may be reduced
Solution Approach 1:
The column portion is precisely positioned within the region bounded by two second lines that are tangent to the addendum circle diameter of the second planetary gear. This nesting ensures the column portion reinforces the carrier without encroaching on the operational space required for planetary gear meshing and movement.
Solution Approach 2:
The column portion is strategically placed only in the specific region where it is needed for moment load reception, rather than uniformly distributing structural elements throughout the carrier. This localized reinforcement maximizes rigidity where required while preserving gear operation space elsewhere.
Data Source
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AI summary
A speed reducer according to an aspect of the invention includes: an internal gear (2); a carrier (3) provided rotatably relative to the internal gear (2); a sun shaft (4) rotatably supported by the carrier (3); and planetary shafts (5) rotatably supported by the carrier (3) and configured to revolve relative to the sun shaft (4). Each of the planetary shafts (5) includes: a first planetary gear (27) meshing with a sun gear (24); and a second planetary gear (28) meshing with the internal gear (2). The carrier (3) is present between two planetary shafts (5) adjacent to each other in the circumferential direction, and the carrier (3) is present in a region (S3) between two second lines (L2) parallel to a first line (L1), the first line (L1) connecting the carrier axis (A1) and a planetary axis (A2), the two second lines (L2) being tangent to an addendum circle diameter (D) of the second planetary gear (28).