Variable-sized cooling air flow path
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Solution Overview
Problem
Air cycle machines in aircraft face challenges in maintaining bearing temperatures due to friction, leading to potential damage and efficiency reduction, as existing cooling methods often require excessive cooling air flow which affects machine performance.
Innovation Solution
A cooling air flow path with an adjustment device that varies the cross-sectional area to control the flow of cooling air based on temperature, using either passive components like thermally dependent snap discs or active systems with temperature sensors and actuators to optimize cooling air flow, ensuring only the necessary amount of cooling is provided to prevent bearing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If excessive cooling air flow is used to cool bearings, then bearing temperature is reduced, but machine performance deteriorates
Solution Approach 1:
The patent implements a dynamic cooling air flow control system that adjusts the cross-sectional area of the cooling air flow path based on real-time bearing temperature conditions. The adjustment device (such as a variable area nozzle or adjustable vane) modifies the flow path geometry to optimize cooling efficiency, ensuring adequate bearing cooling while minimizing the negative impact on machine performance by matching cooling air flow to actual thermal demands rather than using excessive fixed flow rates
Solution Approach 2:
The system changes the physical parameter of the cooling air flow path (cross-sectional area) to control the amount of cooling air reaching the bearings. By varying this geometric parameter in response to temperature conditions, the system achieves optimal balance between bearing temperature control and overall machine performance, preventing both overheating and performance degradation from excessive cooling
2Device complexity
If fixed cooling air flow path is used, then device complexity is reduced, but adaptability to varying thermal demands deteriorates
Solution Approach 1:
The patent introduces a dynamic adjustment mechanism that modifies the cooling air flow path cross-sectional area based on actual bearing temperature conditions. This dynamic capability allows the relatively simple cooling system to adapt to varying thermal demands across different operating conditions, achieving versatility without requiring a completely complex cooling system architecture
Solution Approach 2:
The cooling system incorporates feedback mechanisms (temperature sensing) that enable the system to self-regulate the cooling air flow path area in response to bearing temperature conditions. This self-adjusting capability provides adaptability to thermal demands while maintaining relatively low device complexity, as the system automatically responds to its own operational state without requiring complex external control systems
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
This solution effectively maintains bearing temperatures, optimizing air cycle machine efficiency by adjusting cooling air flow to match thermal demands, preventing damage and enhancing operational capacity.
Implementation Method 1
an adjustment device downstream from the at least one bearing and in fluidic connection with the at least one bearing and the outlet with the adjustment device configured to vary a flow of cooling air through the flow path by adjusting the cross-sectional area of the flow path
Implementation Method 2
During operation, the bearings can experience elevated temperatures due to friction. If the temperature gets too high, the bearings can become damaged, reducing efficiency and possibly causing the air cycle machine to fail. Therefore, it is important to ensure the bearings remain at a sufficiently low temperature.
Data Source
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Figure 2
Figure 3A
AI summary
A cooling air flow path (182) through an air cycle machine can include an inlet (184), at least one bearing (170) downstream from the inlet (184) and in fluidic connection with the inlet (184), an outlet downstream from the at least one bearing (170) and in fluidic connection with the at least one bearing, and an adjustment device (188) downstream from the at least one bearing (170) and in fluidic connection with the at least one bearing (170) and the outlet (186) with the adjustment device (188) configured to vary a flow of cooling air through the flow path by adjusting the cross-sectional area of the flow path. A corresponding method of cooling at least one bearing in an air cycle machine.