Planetary Gearbox Lubricant Tray for Uniform Bearing Feed
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Solution Overview
Problem
In planetary gearboxes, the inhomogeneous lubricant distribution around the shaft circumference leads to uneven lubrication of planetary bearings, resulting in differing temperature behaviors and potential mechanical issues.
Innovation Solution
The design incorporates feed ports on the lubricant-collecting tray with varying opening cross-sections, where the feed port closest to the channel opening has a smaller cross-section, and those further away have larger cross-sections, ensuring a homogeneous lubricant distribution to each planetary pin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single radially extending channel opening is provided on the shaft, then the shaft structure remains simple and strong, but the lubricant distribution around the shaft circumference becomes inhomogeneous
Solution Approach 1:
The patent applies local quality by making the feed ports non-uniform in size rather than identical. Specifically, feed ports are designed with different cross-sectional areas: those closer to the channel opening have smaller cross-sections while those farther away have larger cross-sections. This local variation in feed port geometry compensates for the inhomogeneous lubricant distribution caused by the single channel opening, ensuring each planetary pin receives appropriate lubricant quantity.
Solution Approach 2:
The patent changes the parameter of feed port cross-sectional area along the circumferential direction. By progressively increasing the cross-sectional area of feed ports from those nearest to the channel opening to those farthest away, the system compensates for the decreasing lubricant flow distance and pressure gradient, achieving more uniform lubricant distribution to all planetary pins despite the simple single-channel shaft design.
2Ease of operation
If feed ports are positioned closer to the channel opening, then easier access to lubricant is achieved, but excessive lubricant accumulation occurs at that location
Solution Approach 1:
The patent applies local quality by assigning different cross-sectional dimensions to feed ports based on their circumferential position relative to the channel opening. Feed ports nearer to the channel opening are designed with smaller cross-sections to prevent excessive lubricant accumulation, while those farther away have larger cross-sections to ensure adequate lubricant supply, creating a locally optimized distribution system.
3Ease of manufacture
If all feed ports have identical opening cross-sections, then manufacturing is simplified, but uneven lubrication of planetary bearings occurs
Solution Approach 1:
The patent resolves this contradiction by implementing local quality through non-uniform feed port design. While this increases manufacturing complexity compared to identical feed ports, it ensures reliable and uniform lubrication of all planetary bearings by compensating for the inhomogeneous lubricant flow distribution in the collection space caused by the single radial channel opening.
Solution Approach 2:
The patent employs relatively simple geometric modifications to feed ports (varying cross-sectional areas) that can be achieved through standard manufacturing processes like machining or molding. These modifications, while creating part non-uniformity, represent a cost-effective solution compared to redesigning the entire shaft with multiple channel openings, balancing manufacturing simplicity with functional reliability.
Data Source
AI summary
A planetary gearbox includes a shaft, a planetary carrier, first and second planetary pins arranged on the planetary carrier, first and second planetary gears mounted on the planetary pins via respective bearings, and a lubricant collecting tray. The shaft has a shaft channel for radially conducting a lubricant to an outer face of the shaft and the planetary pins have respective pin channels for conducting the lubricant to the respective bearings. The lubricant-collecting tray has a collection space for collecting the lubricant supplied via the shaft channel and hollow feed ports that open into respective pin channels. The hollow feed port closest to the shaft channel, when viewed in a circumferential direction, has an opening cross-section that is less than an opening cross-section of the other hollow feed port.