Lost Motion Actuator Assembly for Vibration-Resistant Sealing
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Solution Overview
Problem
Existing actuator assemblies for gas turbine engine nacelles are susceptible to relative motion and loads, which can compromise sealing performance, making them less robust and effective.
Innovation Solution
The actuator assembly incorporates a housing, piston rod, and a lost motion device with a slider, biasing member, and sealing members to absorb vibrations and maintain dynamic hydraulic sealing, ensuring robust operation and preventing leaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional actuator assembly is used, then the structure is simple, but the sealing performance deteriorates due to relative motion and loads
Solution Approach 1:
The lost motion device is nested within the actuator assembly, with the slider positioned inside the cylinder and the spring contained within the lost motion device. This nested configuration allows the complex sealing and vibration absorption functions to be integrated without significantly increasing the external dimensions or overall structural complexity of the actuator.
Solution Approach 2:
The lost motion device acts as an intermediary component between the piston rod and the cylinder, absorbing relative motion and vibrations through the slider's movement along the piston rod and the spring's compression. This intermediary mechanism protects the sealing members from direct exposure to harmful vibrations and misalignments, thereby maintaining sealing performance without requiring a completely redesigned actuator structure.
2Reliability
If the actuator is made more robust to resist relative motion, then sealing performance improves, but the device complexity increases
Solution Approach 1:
The lost motion device introduces dynamic elements to the actuator assembly, including the slider that can move along the piston rod and the spring that can compress and expand. These dynamic components allow the actuator to adapt to relative motion and vibrations in real-time, providing robustness and protecting sealing performance without requiring overly rigid or complex structural reinforcements.
Solution Approach 2:
The spring in the lost motion device provides beforehand cushioning by being pre-loaded to counteract vibrations and relative motion before they can reach the sealing members. This proactive cushioning mechanism protects the seals from harmful forces, enhancing robustness without requiring complex shock absorption systems or reinforced structures.
3Reliability
If vibration absorption is added to maintain sealing, then reliability improves, but manufacturing complexity increases
Solution Approach 1:
The vibration absorption function is segmented into a separate lost motion device module that can be independently manufactured and then assembled into the actuator. The slider, spring, and associated components are provided as a discrete assembly, which simplifies manufacturing processes and allows for specialized production of the vibration absorption mechanism without complicating the overall actuator manufacturing.
Solution Approach 2:
The lost motion device serves multiple functions simultaneously: it absorbs vibrations, compensates for misalignment, and protects sealing members. By consolidating these functions into a single integrated component assembly, the design avoids the need for multiple separate vibration absorption devices, alignment mechanisms, and sealing protection systems, thereby reducing overall manufacturing and assembly complexity.
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 solution enhances the robustness of the actuator assembly by effectively absorbing vibrations and maintaining sealing performance, reducing the impact of relative motion and loads on the actuator, thereby improving reliability and maintenance accessibility of gas turbine engines.
Implementation Method 1
The lost motion device is arranged to move relative to the piston rod and is configured to absorb vibrations between the piston rod and the housing
Implementation Method 2
The lost motion device and the piston rod are arranged to move relative to the housing along the first axis
Data Source
Figure 1~2
Figure 3
AI summary
An actuator assembly includes a housing (20), a piston rod (22), and a lost motion device (26). The housing defines a housing bore (36) that extends along a first axis from a first housing end (32) towards a second housing end (34). The piston rod is at least partially disposed within the housing bore. The piston rod defines a piston bore that extends from a first piston end (60) towards a second piston end (62) along the first axis. The lost motion device is at least partially disposed within the housing bore and extends into the piston bore. The lost motion device and the piston rod are arranged to move relative to the housing along the first axis.