Aircraft Engine Thermal Actuator With Nested Bellows Isolation
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Solution Overview
Problem
Existing aircraft engine actuators are not optimally designed to efficiently manage fluid flow based on temperature conditions, leading to inefficiencies in heat exchanger usage.
Innovation Solution
A thermal actuator with a deformable bellows and thermal expansion material, such as wax, is used to control fluid flow through a valve, allowing selective engagement of a heat exchanger or bypass conduit based on temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermal actuator uses a single bellows design, then the structure is simple, but the fluid sealing and thermal response efficiency are insufficient
Solution Approach 1:
The actuator divides the bellows into two separate bellows (first bellows and second bellows) with distinct functions. The first bellows is optimized for thermal expansion response while the second bellows provides fluid sealing, allowing each component to specialize in its primary function without compromise
Solution Approach 2:
The second bellows is positioned within the housing in a nested arrangement relative to the first bellows, with the closed end of the first bellows spaced from the open end of the second bellows. This nested configuration enables both bellows to coexist in the same space while maintaining their respective functions of thermal actuation and fluid sealing
2Ease of operation
If the actuator allows fluid communication through the opening, then access is easy, but fluid leakage occurs
Solution Approach 1:
The second bellows acts as an intermediary element between the fluid port and the opening in the housing. It selectively allows fluid communication when needed while maintaining a seal to prevent unwanted leakage, thus mediating between accessibility and sealing requirements
3Speed
If thermal expansion material is placed inside the bellows, then thermal response is fast, but the structure becomes complex and sealing difficult
Solution Approach 1:
Instead of placing the thermal expansion material inside the bellows as conventionally done, the invention inverts this arrangement by positioning the thermal expansion material in the annular space between the first bellows and the housing. This external placement simplifies the structure while maintaining fast thermal response through direct heat transfer from the fluid
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 thermal actuator effectively manages fluid flow, ensuring efficient use of the heat exchanger by directing fluid through it when temperatures are appropriate, thereby optimizing engine performance.
Implementation Method 1
a thermal expansion material located within the housing between the first bellows and the second end of the housing and outwardly of the first bellows
Implementation Method 2
the first bellows deformable along a longitudinal direction that extends from the first end to the second end
Data Source
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AI summary
A thermal actuator (70), has: a housing (71) having a peripheral wall (71A) extending from a first end (71B) to a second end (71C) and defining a fluid port (71D); a first bellows (72) within the housing (71) and deformable along a longitudinal direction (L1); a thermal expansion material (73) within the housing (71) between the first bellows (72) and the second end (71C) of the housing (71) and outwardly of the first bellows (72); a movable member (74) engaged by the first bellows (72) and received in the housing (71) and protruding through an opening (71E), the movable member (74) movable by the first bellows (72) relative to the housing (71) by expansion and by contraction of the thermal expansion material (73); a second bellows (75) disposed within the housing (71) and engaged by the movable member (74) and fluidly isolating the fluid port (71D) from the opening (71E) of the housing (71); and a fluid-receiving volume (V) defined within the housing (71) by the first bellows (72) and the second bellows (75) and in fluid communication with the fluid port (71D).