Planetary Gear Sun Gear Mounting to Prevent Edge Loading
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Solution Overview
Problem
Conventional planetary-gear mechanisms face issues with reduced service life due to edge loading and axial misalignment of sun gears, which can lead to premature wear and failure.
Innovation Solution
A planetary-gear mechanism with a first sun gear connected to a driving shaft via a stub portion and a screw, where a plate part is preloaded via a spring device to dampen axial shocks and maintain axial alignment, preventing edge loading and ensuring cojoint rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the first sun gear is rigidly connected to the driving shaft, then the axial position is fixed, but edge loading occurs due to thermal expansion and shocks
Solution Approach 1:
The first sun gear is designed with floating capability along the axial direction, allowing it to dynamically adjust its position in response to thermal expansion and shock loads. The spring device provides a compliant connection that maintains axial positioning while accommodating dynamic displacements, preventing edge loading of meshing teeth.
Solution Approach 2:
The spring device changes the stiffness parameter of the connection between the sun gear and driving shaft. By using an elastomeric element with controlled elastic properties, the system transitions from a rigid connection to a compliant one that can absorb axial shocks and accommodate thermal expansion while maintaining reliable axial positioning.
2Strength
If deep groove ball bearings are used on all sun gears, then radial loads are supported, but axial shocks are not damped
Solution Approach 1:
A spring device with an elastomeric element is introduced as an intermediary between the first sun gear and the driving shaft. This intermediary component specifically addresses axial shock transmission by providing elastic damping, while the deep groove ball bearing continues to handle radial loads independently.
Solution Approach 2:
The spring device with elastomeric element is pre-installed in the axial connection path to provide beforehand cushioning against axial shocks. The elastomeric element is designed with appropriate pre-compression to ensure it is already engaged and ready to dampen axial shocks before they occur during operation.
3Manufacturing precision
If axial play is reduced to improve positioning, then alignment improves, but thermal expansion and shocks cause edge loading
Solution Approach 1:
The system transitions from a static, fixed axial play design to a dynamic system where the spring device continuously adapts to changing operating conditions. The elastomeric element maintains consistent contact force while accommodating axial displacements caused by thermal expansion and shocks, preventing edge loading despite reduced axial play.
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 solution extends the service life of the planetary-gear mechanism by damping axial shocks and maintaining axial alignment, thereby preventing edge loading and ensuring long-term operational reliability.
Implementation Method 1
The plate part, e.g., on its side facing away from the spring device, bears against the driving shaft and/or touches the driving shaft at least temporarily
Data Source
AI summary
A planetary-gear mechanism includes a driving shaft and a first sun gear. The first sun gear is connected to the driving shaft for cojoint rotation. The driving shaft has a bore, e.g., an axial bore. The first sun gear has a stub portion, and a screw is screwed into a threaded bore in the stub portion. The screw head presses onto a plate part, which presses onto the stub portion via a spring device or via a spring device and at least one spacer, and the plate part bears against the driving shaft.