Floating Axial Disk Bearing for Low-Speed Planet Gear Wear
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Solution Overview
Problem
Existing planetary gear bearings in wind turbines face issues with complex assembly, increased wear at low speeds, and reduced reliability due to frictional or positive-fit connections, which require significant assembly effort and material weakening.
Innovation Solution
A planetary gear design featuring a floating axial disk with a flat shape and lubricant supply, eliminating the need for frictional or positive-locking connections, ensuring hydrodynamic operation and minimizing wear by maintaining a lubricant film, even at low speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a friction-fit or positive-fit connection is used between the axial sliding bearing and planet carrier web, then the bearing is securely fixed, but the assembly effort becomes considerable and the web material is weakened
Solution Approach 1:
The patent replaces the mechanical friction-fit or positive-fit connection system with a hydrodynamic bearing system. The axial sliding bearing operates on a film of lubricant that separates the bearing surfaces, eliminating the need for mechanical interlocking features like keys, splines, or interference fits. This substitution reduces assembly complexity while maintaining secure fixation through fluid pressure and viscous forces.
Solution Approach 2:
The invention employs hydraulic principles by using a lubricant film to support and secure the axial sliding bearing on the planet carrier web. The lubricant creates a hydrodynamic pressure distribution that holds the bearing in position without requiring mechanical fastening elements, thereby reducing assembly effort while ensuring reliable fixation.
2Force
If profiled floating discs with wedge surfaces are used, then the bearing can support radial loads, but at low speeds below 100 rpm the bearing runs dry leading to increased wear
Solution Approach 1:
The patent modifies the geometric parameters of the floating disc by using a flat surface instead of profiled wedge surfaces. This parameter change allows the bearing to maintain a lubricant film at very low speeds and during startup conditions, preventing dry running and excessive wear while still supporting radial loads through the distributed pressure in the lubricant film.
Solution Approach 2:
The invention uses a simple flat floating disc design that is easier and cheaper to manufacture than profiled discs. While profiled discs provide good radial load support at high speeds, the flat disc design prioritizes reliability at low speeds by maintaining lubrication, accepting that the floating disc may need replacement after a certain service life rather than designing for extended durability through complex geometry.
3Force
If the axial disk has wedge-shaped or ramped surfaces, then it can provide hydrodynamic lift, but it creates linear contact edges that scrape away the lubricant film causing increased wear
Solution Approach 1:
The patent changes the geometric parameters of the axial disk surfaces from wedge-shaped or ramped profiles to flat surfaces. This parameter change eliminates the creation of linear contact edges that would scrape the lubricant film. The flat surfaces maintain adequate hydrodynamic lift through proper clearance design and lubricant supply, while preventing the edge-scraping effect that causes excessive wear.
4Volume of moving object
If a compact design is pursued for the planetary gearbox, then the overall size is reduced, but the available working space for assembly becomes limited
Solution Approach 1:
The patent replaces complex mechanical fastening systems with a hydrodynamic bearing system that requires minimal assembly space. The axial sliding bearing with flat floating disc design can be installed without requiring large clearance zones for alignment and fastening operations, enabling a more compact gearbox layout while keeping assembly procedures simple.
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 design enhances assembly ease, reduces wear, and increases reliability and service life, while allowing for a more compact and efficient planetary gearbox, particularly beneficial in wind turbines.
Implementation Method 1
The floating bearing, supported by the lubricant, ensures that the planetary gear rotates with low friction
Implementation Method 2
a lubricant film exists between the axial disk and the planet gear, ensuring hydrodynamic operation between them
Implementation Method 3
The flat shape of the axial disk on the side facing the web of the planet carrier prevents an edge from contacting the web of the planet carrier if the axial disk is tilted or misaligned. A substantially linear contact between the planet carrier's web and an edge on the axial disk leads to frictional wear on the planet carrier's web
Data Source
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AI summary
The invention relates to a planetary gear set (10) which comprises a planet carrier (12) with a recess for receiving a planet gear axle (24) on which a planet gear (20) is rotatably mounted. Here, at least one axial disk (30) is arranged between a web (14) of the planet carrier (12) and the planet gear (20). According to the invention, the axial disk (30) is mounted in floating fashion in an axial direction (42, 43) between the planet gear (20) and the web (14) of the planet carrier (12), and the axial disk (30) is of flat form on a side (34) facing toward the web (14) of the planet carrier (12). The invention also relates to a wind turbine (60) equipped with a corresponding planetary gear set (10).