Planetary Gearbox Plain Bearing Cooling Channel for Thermal Stability
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Solution Overview
Problem
Plain bearings in gas turbine engines face challenges with high operating temperatures and limited oil availability, leading to thermal deformations and reduced service life due to inefficient heat dissipation and lubrication in highly loaded regions.
Innovation Solution
A planetary gear box design incorporating a channel or cooling channel within the plain bearing to direct transmission oil through the carrier element, effectively dissipating heat and reducing thermal deformations, while ensuring consistent lubrication and load-bearing capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transmission oil is supplied to the plain bearing, then lubrication is improved, but most of the oil flow does not reach the highly loaded region where highest temperatures occur
Solution Approach 1:
The bearing gap is segmented into multiple regions with dedicated oil supply channels. The invention provides at least one first oil supply channel and at least one second oil supply channel that are spatially separated and directed toward different regions of the bearing gap, ensuring that highly loaded regions receive adequate lubrication regardless of oil flow distribution
Solution Approach 2:
Different regions of the bearing gap are provided with different oil supply characteristics. The invention places oil supply channels at specific locations (e.g., radially outward region and radially inward region) to match the local lubrication needs of different bearing regions, with channels positioned to target highly loaded zones directly
2Force
If plain bearings are used in highly loaded regions, then load-bearing capacity is achieved, but thermal deformations occur due to high operating temperatures
Solution Approach 1:
Oil supply channels are positioned and configured to deliver cooling lubricant to highly loaded regions before thermal deformations can significantly affect bearing functionality. The channels are arranged to preemptively cool critical zones where temperatures rise most rapidly under high loads
Solution Approach 2:
Transmission oil serves as an intermediary substance that performs dual functions: lubrication and cooling. The oil is circulated through channels positioned to reach highly loaded regions, absorbing heat and reducing thermal deformations while maintaining lubrication films between bearing surfaces
3Ease of manufacture
If channels with open cross section are used, then manufacturing is simplified, but transmission oil escapes into the bearing gap reducing cooling efficiency
Solution Approach 1:
A sealing arrangement comprising a sealing element and a sealing surface is provided to close the channel cross section. The sealing element (such as an O-ring or lip seal) flexibly adapts to the channel geometry and prevents oil escape, while the sealing surface provides a mounting interface that maintains the closed configuration under operating conditions
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 the service life and thermal stability of plain bearings by efficiently dissipating heat and maintaining a consistent lubrication system, reducing thermal deformations and maximizing the load-bearing capacity.
Implementation Method 1
at least one channel is provided in the carrier element in such a way as to extend radially inside the outer side of the carrier element, extending in the axial direction of the carrier element at least in some region or regions
Implementation Method 2
The channel is embodied with a cross section that is closed with respect to the bearing gap
Implementation Method 3
They slide on one another against the resistance caused by sliding friction. This can be kept low by selecting a low-friction pair of materials, by lubrication or by the production of a lubricating film which separates the two contact surfaces
Implementation Method 4
The sliding resistance has the effect that some of the kinetic energy is converted into heat energy, which flows into the two bearing parts and may have to be dissipated
Data Source
AI summary
A planetary gear box for a gas turbine engine, has a planet carrier with a carrier element and a planet gear. The planet gear is mounted rotatably via a plain bearing on the carrier element. An oil feed pocket is provided in the region of an outer side of the carrier element, via which feed pocket oil can be passed into a bearing gap between the outer side of the carrier element and an inner side of the planet gear. In the circumferential region of a main load direction of the plain bearing, the carrier element is formed with at least one channel carrying transmission oil. The channel extends in the carrier element radially inside the outer side of the carrier element, extending in the axial direction of the carrier element, and includes a cross section closed with respect to the bearing gap.