Fixed Upper Bearing Aircraft Shock Strut Weight Reduction
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Solution Overview
Problem
Aircraft shock struts face challenges in reducing weight while maintaining durability, as lighter materials used to achieve weight reduction often result in premature wear and increased maintenance costs due to susceptibility to wear and corrosion.
Innovation Solution
The use of a fixed upper bearing in the shock strut allows for the implementation of lighter weight materials for the cylinder, such as titanium, without excessive wear, by shifting the wear burden from the cylinder to the bearing, thereby reducing overall weight without compromising durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If lighter weight materials are used for the cylinder, then weight reduction is achieved, but wear resistance deteriorates causing premature wear
Solution Approach 1:
A fixed upper bearing is introduced as an intermediary component between the piston and cylinder. This bearing carries the sliding engagement and wear, allowing the cylinder to be made from lighter weight materials while maintaining wear resistance through the bearing interface.
Solution Approach 2:
The wear-resistant function is segmented from the cylinder structure and assigned to a separate bearing component. This allows the cylinder to be optimized for weight while the bearing handles the wear and corrosion challenges independently.
2Weight of moving object
If traditional bearing arrangement is used (upper bearing fixed to piston), then structural integrity is maintained, but weight reduction is limited due to cylinder material constraints
Solution Approach 1:
The conventional arrangement has the upper bearing fixed to the moving piston. This invention inverts the arrangement by fixing the upper bearing to the stationary cylinder, which simplifies the overall structure and enables weight reduction in the piston and cylinder assembly.
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 design effectively reduces the weight of the shock strut while maintaining durability, reducing maintenance costs and improving performance by utilizing lighter materials without premature wear issues.
Implementation Method 1
a trapped volume of gas is compressed as the shock strut is axially compressed, and a volume of oil is metered through an orifice. The gas acts as an energy storage device, such as a spring, so that upon termination of a compressing force the shock strut returns to its original fully-extended length
Implementation Method 2
Shock struts also dissipate energy by passing the oil through the orifice so that as the shock absorber is compressed or extended, its rate of motion is limited by the damping action from the interaction of the orifice and the oil
Implementation Method 3
at least two bearings provide for sliding engagement of the telescoping cylinders
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
An aircraft shock strut (12) includes a cylinder (32) and a piston (30) movable within the cylinder. A lower bearing (40) and an upper bearing (46) provide sliding engagement between the cylinder and the piston. The upper bearing is fixed to the cylinder and provides sliding engagement with an outer surface the piston. An upper bearing that is fixed to the cylinder facilitates use of lighter weight materials for the cylinder without sacrificing durability.