Floating Axial Disk Bearing for Planet Gears at Low Speeds
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Solution Overview
Problem
Existing planetary gear bearings in wind turbines face high assembly complexity, increased wear, and reduced reliability due to non-positive or positive connections and hydrodynamic axial bearings that run dry at low speeds, leading to excessive wear and maintenance challenges.
Innovation Solution
A planetary gear design featuring a sun shaft, planet carrier with a recess for the planetary gear axle, and a flat axial disk mounted in a floating manner between the planet carrier and planet wheel, eliminating the need for non-positive connections and ensuring hydrodynamic operation with a lubricant film, reducing friction and wear, and simplifying assembly and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a friction-fit or positive-fit connection is used between the axial sliding bearing and the planet carrier web, then the bearing is securely mounted, but the assembly effort becomes considerable
Solution Approach 1:
The invention extracts the fastening function from the bearing mounting process. The axial floating disc is designed to be retained by the planet carrier web through a retaining groove and retaining element, separating the mounting function from the fastening function. This allows the bearing to be securely mounted without requiring friction-fit or positive-fit connections that demand considerable assembly effort.
Solution Approach 2:
The invention introduces a retaining groove and retaining element as intermediary structures between the axial floating disc and the planet carrier web. These intermediaries provide secure retention of the bearing while eliminating the need for complex fastening operations, thus reducing assembly effort while maintaining reliable mounting.
2Force
If profiled floating discs with wedge surfaces are used, then the bearing can support axial loads, but at low speeds below 100 rpm the bearing runs dry leading to increased wear
Solution Approach 1:
The invention changes the geometric parameters of the floating disc from profiled wedge surfaces to a flat design. This parameter change eliminates the hydrodynamic effect that causes the bearing to run dry at low speeds, while the flat surface maintains adequate axial load support through direct contact and lubrication film formation without requiring high rotational speeds.
Solution Approach 2:
Instead of using wedge surfaces that rely on hydrodynamic pressure generation (which fails at low speeds), the invention inverts the approach by using a flat surface that relies on boundary lubrication and direct contact mechanics. This inverted approach to axial load support eliminates the speed dependency and prevents dry running conditions.
3Power
If the axial disk has wedge-shaped or ramped surfaces, then it can generate hydrodynamic pressure, but it causes edge contact with the planet carrier web leading to frictional wear and lubricant film breakdown
Solution Approach 1:
The invention changes the surface geometry parameter of the axial disk from wedge-shaped or ramped surfaces to a flat surface. This parameter change eliminates the edge contact phenomenon that causes frictional wear and lubricant film scraping, while the flat surface maintains adequate hydrodynamic pressure generation through its large contact area and proper lubrication film formation.
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 provides reduced wear, increased reliability, and simplified assembly and maintenance, with improved service life and cost efficiency, even at low speeds, while maintaining a compact and efficient design.
Implementation Method 1
a lubricant film is present between the axial disk and the planet gear, ensuring hydrodynamic operation between the planet gear and the axial disk
Implementation Method 2
ensuring hydrodynamic operation between the planet gear and the axial disk
Data Source
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AI summary
The invention relates to a planetary gear (10) comprising a planet carrier (12) with a recess for receiving a planet gear shaft (24) on which a planet gear (20) is rotatably mounted. 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 floatingly mounted 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 planar on one side (34) facing the web (14) of the planet carrier (12). The invention also relates to a wind turbine (60) equipped with a corresponding planetary gear (10).