Exhaust Case Heat Shield Assembly for Bearing Oil Overheat Protection
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Solution Overview
Problem
In gas turbine engines, the bearing housing oil is overheated due to thermal conduction from hot exhaust gases, leading to oil degradation and potential mechanical damage, and existing thermal blankets are costly and require precise fitting to avoid damage.
Innovation Solution
An integrated heat shield is secured to the exhaust cone and connected to an annular mounting bracket, which extends from the exhaust case, providing radial protection between the exhaust cone and the bearing housing, with an air-filled gap for insulation and optional cooling air flow to regulate temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a thermal blanket of heat insulating material is fitted to the bearing housing, then the oil temperature is protected from overheating, but the cost increases and the installation becomes complex requiring accurate fitting
Solution Approach 1:
The heat shield acts as an intermediary component positioned between the exhaust cone and bearing housing, blocking thermal conduction paths without requiring direct contact with the bearing housing. This eliminates the need for complex thermal blanket installation while effectively protecting the oil temperature.
Solution Approach 2:
The heat shield uses simple, inexpensive materials such as thin sheet metal or ceramic tiles that are easier and cheaper to manufacture and install compared to thermal blankets. These materials provide effective thermal protection without requiring precise fitting or complex installation procedures.
2Object-affected harmful factors
If a thermal blanket is used to protect the bearing housing, then heat insulation is achieved, but fretting, vibration and physical damage may occur due to improper fitting
Solution Approach 1:
The heat shield serves as a rigid intermediary structure that maintains a consistent air gap between the exhaust cone and bearing housing. This eliminates the flexibility issues of thermal blankets that lead to fretting and vibration, providing stable, reliable heat insulation without physical degradation.
Solution Approach 2:
The invention changes the physical state from a flexible thermal blanket to a rigid heat shield structure, fundamentally altering the mechanical properties. This transformation eliminates vibration and fretting issues while maintaining effective heat insulation through the rigid structure and air gap.
3Object-affected harmful factors
If the exhaust cone is removed to install a thermal blanket, then the bearing housing can be protected, but the installation time and complexity increase
Solution Approach 1:
The heat shield is designed as a separate, modular component that can be independently installed without removing the exhaust cone. This segmentation allows the heat shield to be fitted through accessible areas, dramatically reducing installation time and complexity compared to blanket installation requiring exhaust cone removal.
Solution Approach 2:
The heat shield is positioned as an intermediary element that can be installed through alternative access paths, eliminating the need to remove the exhaust cone. This approach maintains the integrity of the exhaust system while enabling quick installation of thermal protection.
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 integrated heat shield effectively reduces heat conduction to the bearing housing, preventing oil overheating and degradation, while being more cost-effective and easier to install than traditional thermal blankets.
Implementation Method 1
an integrated heat shield is secured to the exhaust cone and connected to an annular mounting bracket, which extends from the exhaust case, providing radial protection between the exhaust cone and the bearing housing, with an air-filled gap for insulation
Implementation Method 2
with an air-filled gap for insulation and optional cooling air flow to regulate temperature
Data Source
AI summary
A gas turbine engine exhaust case assembly comprises: an exhaust case having an axis and defining an annular gas path; a bearing housing coaxially supported within the exhaust case; an exhaust cone coaxial and rearward of the exhaust case; a heat shield joined to the exhaust cone, the heat shield being disposed radially between the exhaust cone and the bearing housing; and a mounting bracket extending from the exhaust case and joining the exhaust case and the exhaust cone together.