Secondary Load Path Locking for Backlash-Free THSA Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing flight actuator systems face challenges in reliably detecting engagement of the secondary load path without creating backlash, which can lead to undesirable 'flutter' effects during switching from the primary to the secondary load path, and require complex devices for validation.
Innovation Solution
A secondary load path assembly with a locking unit that secures the transfer plate to the secondary nut, using a slidable lock and spring mechanism to eliminate relative movement and provide a reliable indication of engagement, allowing for checkable operation without the need for complex parts or 'fuse' components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a checkable shear pin is used to detect secondary load path engagement, then reliable detection is achieved, but device complexity increases and backlash is created
Solution Approach 1:
The patent extracts the detection function from a separate complex device (shear pin) and integrates it into the existing secondary nut structure. The secondary nut itself becomes the detection element through its axial movement relative to the opening in the transfer plate, eliminating the need for separate detection components and reducing overall device complexity while maintaining reliable detection capability.
Solution Approach 2:
The secondary nut is given multiple functions: it serves both as a load transfer component and as a detection element. When the secondary load path engages, the secondary nut axially moves and its position relative to the opening in the transfer plate provides direct indication of engagement status. This multi-functionality eliminates the need for separate detection devices and reduces complexity.
2Device complexity
If the secondary load path parts are allowed to move relative to each other during load transfer, then the system is simpler, but backlash is created causing flutter
Solution Approach 1:
The lock acts as an intermediary element between the secondary nut and the transfer plate. It engages with both components to prevent relative axial movement, thereby eliminating backlash. The lock allows the necessary structural simplicity while ensuring stable, backlash-free operation during secondary load path engagement.
3Stability of the object's composition
If a locking unit is added to eliminate backlash, then stability is improved, but device complexity increases
Solution Approach 1:
The locking unit is merged with the existing secondary load path components (secondary nut and transfer plate) rather than being a completely separate system. The lock integrates with these components to prevent relative movement, providing stability while minimizing the increase in device complexity through unified design.
Solution Approach 2:
The lock serves multiple functions: it prevents relative axial movement between the secondary nut and transfer plate to eliminate backlash, and it also serves as part of the detection mechanism by maintaining the positional relationship that indicates secondary load path engagement. This multi-functionality justifies its inclusion while minimizing complexity increase.
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
Ensures seamless load transfer to the secondary path without backlash and provides a reliable, checkable method for detecting engagement, enhancing flight stability and compliance with regulatory requirements.
Implementation Method 1
the locking unit comprising a lock arranged to axially move to a lock position in which it is located in the clearance between the secondary nut and the opening to lock the secondary nut to the transfer plate
Data Source
Figure 1~2
Figure 3~4D
Figure 5A~6
AI summary
A secondary load path assembly comprising: a secondary load path comprising: a plate (60); a secondary nut (70); and a transfer plate (65) secured to the plate (60) and configured to connect the plate and the secondary nut in load transfer engagement, the transfer plate (65) having an opening (650) therethrough, an axis defined through the opening, and the secondary nut protruding axially through the opening; wherein, in a state in which load is not transmitted via the secondary load path, a clearance is provided between the secondary nut and the opening; the assembly further comprising: a locking unit (80) configured to lock the secondary nut to the transfer plate when load is to be transmitted through the secondary path, the locking unit comprising a lock (100) arranged to axially move to a lock position in which it is located in the clearance between the secondary nut and the opening to lock the secondary nut to the transfer plate.