Planetary Carrier Flex-Bolt Structure for Load Misalignment
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Solution Overview
Problem
Existing planetary gear systems face misalignment issues due to load-related deformations, particularly in wind turbines, where permanently changing loads cause errors in tooth meshing, and the use of flex pins limits load-bearing capacity by fixing the pin in only one cheek.
Innovation Solution
A planetary carrier design featuring a first and second cheek, a pin, and a bushing where the pin's second axial end is fixed in the bushing, allowing the bushing to be free-floating and forming cavities with a stiffening rib, enhancing load-bearing capacity and adaptability to varying loads by modifying deformation behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the number of planet wheels is increased to increase transmissible power, then the load-bearing capacity improves, but the distance between adjacent planet wheels decreases making web placement problematic
Solution Approach 1:
The planetary carrier is divided into a first cheek and a second cheek connected by webs, with the pin and bushing assembly providing structural support between the cheeks. This segmentation allows the carrier to accommodate more planet wheels by distributing structural support across multiple elements rather than requiring large inter-wheel distances.
2Device complexity
If all forces between cheeks are transmitted via planetary bolts in the absence of webs, then the structure is simplified, but deformations of the planetary bolts occur leading to misalignment
Solution Approach 1:
The bushing acts as an intermediary element between the pin and the second cheek, providing a bearing surface that reduces friction and wear. This intermediary structure allows force transmission while maintaining alignment precision, preventing the deformations that would occur if forces were transmitted directly through simple planetary bolts.
3Strength
If a second cheek is added to absorb higher loads, then the load-bearing capacity improves, but the construction of traditional flex pins prevents their use
Solution Approach 1:
The bushing is designed with a free-floating second axial end that can tilt and deform elastically in response to varying loads. This dynamic capability allows the pin-bushing assembly to accommodate higher loads absorbed by the second cheek while maintaining flexibility and compensating for deformations, overcoming the limitation of traditional rigid flex pin constructions.
4Manufacturing precision
If gearing correction is applied to compensate for misalignment at a certain load, then the tooth meshing errors are compensated, but errors occur again under deviating loads
Solution Approach 1:
The bushing material and geometry are designed to allow elastic deformation and tilting under varying load conditions. This parameter change in the bushing's physical state enables automatic compensation for misalignment across different load scenarios, providing adaptability without requiring separate gearing corrections for each load condition.
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
This design increases the load-bearing capacity, allows for larger or more planet wheels, and compensates for deformations, improving the suitability for changing loads without the need for webs between cheeks, while maintaining flexibility in planetary bolts.
Implementation Method 1
A flex pin is a flexible planetary bolt which compensates for load-related deformations and thus prevents misalignment of a planet wheel
Implementation Method 2
A first axial end of the pin is fixed in the first cheek, and a second axial end of the pin is fixed in the bushing
Data Source
AI summary
A planetary carrier includes a first cheek, a second cheek, at least one pin, and at least one bushing. A first axial end of the pin is fixed in the first cheek, and a first axial end of the bushing is fixed in the second cheek. At least a portion of the pin protrudes into the bushing, and a second axial end of the pin is fixed in the bushing. A second axial end of the bushing is free-floating, and the bushing forms at least a first cavity and a second cavity. The portion of the pin that protrudes into the bushing protrudes into the first cavity. The bushing forms a wall that separates the first cavity and the second cavity from each other and at least one stiffening rib extends through the second cavity.