Planetary Gear Layout With Uneven Planet Spacing for Load Adaptation
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Solution Overview
Problem
Existing planetary gearboxes face high variant costs due to oversizing to accommodate the highest load case, while varying the number of planet gears is limited by sun and ring gear teeth configuration, leading to inefficiencies.
Innovation Solution
A planetary gearbox design with unevenly distributed planet gears, where the axes of rotation are offset by specific angles to accommodate varying load cases using constructionally identical components, allowing adaptation to specific loads without oversizing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gearbox is dimensioned to withstand the highest load case, then reliability is improved, but component costs increase due to oversizing
Solution Approach 1:
The patent applies dynamics by making the number of planet gears variable rather than fixed. The planet gear set can be configured with different numbers of planet gears (e.g., 2, 3, 4, or 5) depending on the specific load case, allowing the transmission to adapt its load-bearing capacity dynamically. This resolves the contradiction by enabling the gearbox to be optimized for each specific application rather than being oversigned for maximum load, thus reducing component costs while maintaining reliability for the intended load case.
Solution Approach 2:
The patent employs parameter changes by varying the number of planet gears as a key design parameter. By changing this parameter, the gearbox can be precisely dimensioned for different load cases without requiring a completely different design. This allows optimization of component costs by matching the planet gear count to the actual load requirements rather than using a fixed oversized configuration.
2Adaptability or versatility
If the number of planet gears is varied to adapt to different load cases, then adaptability is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing a planetary gear set that can serve multiple load cases with the same basic components. By varying only the number of planet gears while keeping the sun gear, ring gear, and carrier structure identical, the same gearbox design can be universally applied to different applications. This reduces device complexity compared to designing separate gearboxes for each load case, while maintaining high adaptability.
3Object-generated harmful factors
If planet gears are unevenly spaced, then noise emissions are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies asymmetry by intentionally spacing the planet gears unevenly around the sun gear. Instead of uniform angular distribution, the planet gears are positioned at different angular intervals. This asymmetric arrangement causes the planet gears to enter and exit the meshing region at different times, smoothing out the load transitions and reducing noise emissions. The asymmetry principle directly addresses the noise reduction goal while the patent provides specific angular positioning guidelines to manage manufacturing precision requirements.
Data Source
AI summary
A planetary gearbox, including N planet gears, a sun gear with zS teeth, and a ring gear with zH teeth. Axes of rotation of two of the N planet gears are arranged offset relative to a center axis of the sun gear by an angle φ′ determined according to the following equation:φ ′=360°N(1+N-1zH-zS).