Aircraft Hydraulic Filter Retaining Member Design
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Solution Overview
Problem
Aircraft hydraulic filtering devices face challenges with large torque requirements for tightening filters, leading to cumbersome and heavy torque wrenches, excessive stress on threading, and risk of degradation due to frequent screwing and unscrewing.
Innovation Solution
A filtering device with a hydraulic block featuring a retaining member that axially secures the filter, using a second coaxial thread for the retainer, which is subjected to significant tightening only during installation, while the filter's thread experiences reduced stress, minimizing fatigue and ensuring secure attachment without frequent tightening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If significant tightening torque is applied to secure the filter, then the filter attachment reliability is improved, but the threading stress and fatigue degradation risk increase
Solution Approach 1:
The patent divides the fastening function into two separate threads: a first thread for initial filter attachment and a second thread for applying the final significant tightening torque. This segmentation allows each thread to have optimized functions - the first thread handles frequent connection/disconnection with minimal stress, while the second thread provides the necessary clamping force without subjecting itself to fatigue cycling.
Solution Approach 2:
The patent introduces a ferrule as an intermediary component that mediates between the filter and the hydraulic block. The ferrule is screwed onto the first thread and then clamped by the second thread, allowing the significant tightening torque to be applied to the ferrule rather than directly to the filter-thread interface, thereby protecting the first thread from high stresses.
2Reliability
If significant tightening torque is applied to secure the filter, then the filter attachment reliability is improved, but the torque wrench size and weight increase
Solution Approach 1:
By segmenting the tightening function across two threads, the patent enables the use of a smaller, lighter torque wrench. The first thread requires minimal tightening for connection, and the second thread, which does require significant torque, can be accessed with a more manageable wrench due to its specific geometric configuration and location.
Solution Approach 2:
The patent utilizes the radial dimension by positioning the second thread at a different radius from the center axis compared to the first thread. This dimensional change allows the application of significant torque through a more compact lever arm, reducing the size and weight requirements of the torque wrench while still achieving the necessary clamping force.
3Reliability
If significant tightening torque is applied to secure the filter, then the filter attachment reliability is improved, but the operator effort increases
Solution Approach 1:
The patent segments the tightening operation into two distinct phases: a light initial tightening on the first thread for connection, and a final significant tightening on the second thread. This segmentation allows the operator to apply minimal effort for the majority of the operation (connection), with the high-effort phase being brief and focused, thereby reducing overall operator fatigue.
Solution Approach 2:
The first thread performs a preliminary action of connecting and positioning the filter securely before the second thread applies the final significant torque. This preliminary connection stabilizes the assembly, making the subsequent high-torque operation easier and more controlled, thereby reducing the effective effort required by the operator.
Data Source
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AI summary
The device has a hydraulic block (1) receiving a removable hydraulic filter (2), where the filter is screwed in an inlet of an internal thread (8) of the hydraulic block. The block has a clamp (101) for axially retaining the filter, when the filter is screwed on the hydraulic block. The block has a base coaxial to the inlet of the thread. A nut (102) fixes the clamp on the hydraulic block and is screwed in a base of the thread. The clamp has a base supported on a shoulder of the block.