Hybrid Duplex Ball Bearing Assembly Preload Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-speed gas turbine engine ball bearing assemblies face challenges in withstanding high thrust loads at low altitudes and managing lubricant flow to prevent excessive wear and vibration, as they are prone to radial load excursions and thermal issues due to lubricant churning.
Innovation Solution
A preloaded hybrid duplex ball bearing assembly with a preload spring applying axial force to angular contact bearings, allowing the forward bearing to handle radial loads and the aft bearing to carry only axial force, with a lubricant recirculation system to prevent overheating and wear, featuring a design where the aft outer race is not radially loaded and forms a clearance fit with the forward outer race.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If excess lubricant is supplied to high-speed bearings, then the load-bearing films are supported and frictional heat is carried away, but the bearing experiences unacceptable temperature rise due to churning losses
Solution Approach 1:
The patent changes the physical state and flow parameters of the lubricant by introducing a centrifugal pump system that actively controls lubricant circulation. The pump creates a controlled flow regime that maintains adequate lubrication films while preventing excessive lubricant accumulation that causes churning losses and temperature rise.
Solution Approach 2:
The patent replaces the passive lubrication system (relying on natural lubricant distribution) with an active mechanical lubrication system using a centrifugal pump. This substitution enables precise control over lubricant delivery, ensuring adequate film support without excessive lubricant that would cause churning and overheating.
2Reliability
If lubricant is trapped in the bearing, then lubrication is maintained, but the lubricant is heated by shearing action of passing balls, decreasing effectiveness and useful life
Solution Approach 1:
The patent implements continuous lubricant circulation through a centrifugal pump system that constantly moves lubricant through the bearing assembly. This continuous flow prevents lubricant from being trapped and subjected to prolonged shearing action, maintaining lubrication effectiveness while preventing excessive temperature buildup through constant refreshment of the lubricant.
Solution Approach 2:
The centrifugal pump acts as an intermediary device that mediates between lubricant supply and bearing requirements. It controls the lubricant flow to ensure adequate lubrication while preventing trapping and excessive heating through regulated circulation, extending lubricant life and maintaining effectiveness.
3Force
If the bearing system is designed to withstand high thrust loads, then thrust capacity is improved, but the system becomes heavier
Solution Approach 1:
The patent changes the operational parameters of the bearing system by implementing preloading through a spring mechanism. This preloading optimizes the contact between bearing elements, enabling the bearing to withstand high thrust loads more efficiently without requiring increased size or weight. The parameter change in loading distribution allows lighter bearing construction while maintaining thrust capacity.
4Adaptability or versatility
If radial loads are carried by the bearing system at high altitude, then the bearing may experience excursion and skidding, causing excessive wear and vibration
Solution Approach 1:
The patent applies preliminary preloading to the bearing system using a spring mechanism that establishes optimal contact conditions before operation. This preliminary action ensures that the bearing elements are properly engaged and positioned to handle varying load conditions, including the transition from thrust-dominated loads at low altitude to more balanced thrust-radial load conditions at high altitude, preventing excursion and skidding.
Solution Approach 2:
The patent implements a dynamic bearing system with preloading that can adapt to changing operational conditions. The spring-based preloading mechanism allows the bearing to dynamically adjust to varying thrust and radial load ratios that occur during altitude changes, maintaining stability and preventing wear-causing excursion and skidding across different operational regimes.
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 ball excursion and skidding, maintains thrust loading dominance over radial loading, and enhances durability by ensuring lubricant circulation and heat management, thus improving the bearing system's ability to handle variable thrust loads and altitude conditions.
Implementation Method 1
a preload spring disposed adjacent the aft bearing and configured to apply an axial force to push the aft bearing toward the forward bearing
Implementation Method 2
ensuring lubricant circulation and heat management
Data Source
AI summary
According to one aspect of the present invention, a preloaded hybrid duplex bearing assembly is disclosed. A hybrid duplex ball bearing assembly includes a forward bearing, an aft bearing, and a preload spring, the preload spring disposed adjacent the aft bearing and configured to apply an axial force to push the aft bearing toward the forward bearing, where the forward bearing and aft bearing share an inner race. The forward bearing and the aft bearing are angular contact bearings each including a contact angle, and the contact angles of the forward bearing and the aft bearing converge at a point within the bearing assembly. In one embodiment, the aft bearing is not radially loaded and carries only the axial force of the preload spring. In at least one embodiment, the forward bearing forms a radial clearance fit with the aft bearing such that the aft bearing carries no radial load.