Plain Bearing Pivot Recess Layout for Heat and Alignment
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Solution Overview
Problem
In gas turbine engines, particularly those with epicyclic gear trains, conventional plain bearings experience misalignment and temperature issues due to non-uniform heating and trapped air in flexibility zones, leading to reduced reliability and efficiency.
Innovation Solution
A pivot with a central barrel and axially opposite circumferential grooves, featuring hollow recesses in the cantilevered side parts to modify material distribution and reduce rigidity, allowing for localized temperature control and improved heat transfer, while maintaining alignment quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If circumferential grooves are provided to create flexibility zones in the pivot, then misalignment between the active surface and bearing surfaces is reduced, but heat evacuation is impaired due to trapped air in the flexibility zone
Solution Approach 1:
The invention applies local quality by making the flexibility zone non-uniform: the cantilevered side part is hollowed out by a recess only in the heating zone (upstream of the oil supply slot), while other areas maintain full material. This localized modification allows heat evacuation where needed while preserving flexibility where required, resolving the contradiction between alignment quality and temperature control.
2Temperature
If the pivot structure is made more rigid to improve structural integrity, then heat conduction improves, but misalignment between bearing surfaces increases
Solution Approach 1:
The recess is strategically positioned only in the heating zone of the cantilevered side part, creating local thermal management without compromising overall structural integrity. The flexibility zone maintains its misalignment-compensating function in non-heating areas while the heated area gains improved heat conduction through the recess configuration.
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 effectively reduces temperature and misalignment, enhancing the reliability and efficiency of the gear train by promoting heat transfer and limiting hot spots, thereby improving the structural integrity and lubrication performance.
Implementation Method 1
heating of the active surface of the pivot... in particular in a zone situated circumferentially just upstream of the passage, such as a slot, for supplying oil
Implementation Method 2
one cause of the aforementioned local increase in temperature was linked to the presence of air trapped in the flexibility zone. The absence of material limits the conduction of heat and therefore the evacuation of calories
Data Source
Figure 1~2
Figure 3~5
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AI summary
The invention concerns a pivot (5) for a plain bearing with planetary gear set, the pivot having axially opposite, laterally open, circumferential grooves (25a), providing flexibility to the pivot and which radially separate two axially opposite, lateral end portions of a central barrel from two cantilevered lateral portions (27a, 27b) of the pivot. At least one of the cantilevered lateral portions is hollowed out by at least one recess (65a).