Dual-Stage Shock Strut Servicing With Temperature-Based Pressure Matching
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Solution Overview
Problem
Current methods for servicing aircraft landing gear shock struts are inefficient and require extensive bleeding procedures, especially when dealing with varying ambient temperatures, which can affect internal fluid levels and shock strut functionality.
Innovation Solution
A method for servicing dual-stage, mixed gas/fluid shock struts involves charging secondary and primary chambers with compressed gas and oil, using temperature-specific reference curves to ensure proper pressure and extension matching, minimizing bleeding and cycling, and allowing for efficient servicing across a range of temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional shock strut servicing methods are used, then the shock strut can be serviced, but extensive bleeding procedures and shock strut cycling are required, increasing service time and complexity
Solution Approach 1:
The patent applies preliminary action by pre-charging the secondary gas chamber with compressed gas before servicing the primary chamber. This preparatory step establishes the correct pressure environment in advance, allowing the primary chamber to be filled with oil and gas simultaneously without requiring subsequent bleeding or cycling operations to achieve proper fluid levels and pressure balance.
2Ease of manufacture
If traditional servicing methods are used, then the shock strut can be serviced, but extensive bleeding procedures are required, increasing process complexity
Solution Approach 1:
By pre-charging the secondary gas chamber before servicing the primary chamber, the patent eliminates the need for complex bleeding procedures. The preliminary establishment of pressure in the secondary chamber creates favorable conditions for simultaneous oil and gas filling in the primary chamber, simplifying the overall servicing process.
Solution Approach 2:
The secondary gas chamber acts as an intermediary system that facilitates the servicing of the primary chamber. By establishing the correct pressure environment in the secondary chamber first, it mediates the filling process of the primary chamber, allowing oil and gas to be introduced simultaneously without requiring complex bleeding or cycling operations.
3Ease of operation
If shock strut servicing is performed without temperature compensation, then the servicing process is simpler, but internal fluid levels and shock strut functionality are affected by varying ambient temperatures
Solution Approach 1:
The patent applies parameter changes by using temperature-specific reference curves to determine the appropriate amount of compressed gas to charge into the secondary and primary chambers. Based on the measured ambient temperature, the technician selects the corresponding reference curve to calculate the precise gas quantity needed, compensating for thermal expansion or contraction of the internal fluids and maintaining reliable shock strut functionality across different temperature conditions.
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 method provides a more time-efficient and precise way to maintain shock strut fluid levels, reducing the need for extensive bleeding and minimizing shock strut cycling, ensuring optimal functionality regardless of ambient temperature.
Implementation Method 1
charging a secondary gas chamber with a first quantity of compressed gas... charging the primary chamber with a second quantity of compressed gas
Implementation Method 2
a secondary chamber pressure corresponds to the servicing temperature... a primary chamber pressure and a shock strut extension corresponds to a gas servicing reference curve
Implementation Method 3
pumping oil into a primary chamber of the dual-stage, mixed gas/fluid shock strut... the dual-stage, mixed gas/fluid shock strut extends in response to the oil being pumped into the primary chamber
Implementation Method 4
The gas acts as an energy storage device, similar to a spring, so that upon termination of a compressing force the shock strut returns to its original length
Implementation Method 5
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
Data Source
Figure 1A
Figure 1B
Figure 1C~1D
AI summary
A method for servicing a dual-stage, mixed gas/fluid shock strut (100) may comprise measuring a servicing temperature, charging a secondary gas chamber (140) with compressed gas, wherein a secondary chamber pressure corresponds to the servicing temperature, pumping oil into a primary chamber (130) of the shock strut, and charging the primary chamber with compressed gas.