Uplock Hydraulic Delay Valve for Early Degradation Diagnosis
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Solution Overview
Problem
Existing methods for diagnosing the degradation of latching mechanisms in aircraft landing gear and hatches are inadequate due to the high pressure build-up rate in hydraulic cylinders, making it difficult to detect performance degradation before a complete failure occurs, and require frequent maintenance schedules that are not optimized.
Innovation Solution
A method involving a hydraulic supply circuit with a delay valve that controls the application of pressure to the cylinder, allowing for the diagnosis of degradation based on the release time of the hook, without the need for pressure sensors, by delaying the application of full pressure and comparing the release time to predetermined thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If pressure is applied rapidly to the hydraulic cylinder for quick unlocking, then unlocking speed is improved, but the ability to detect degradation before failure deteriorates
Solution Approach 1:
The system performs a preliminary diagnostic action by applying a limited pressure (first pressure level) before the full operating pressure. This preliminary pressure application allows measurement of the unlocking time to detect degradation, while the full pressure is only applied if needed for actual unlocking operation.
Solution Approach 2:
The pressure application process is segmented into two distinct phases: a diagnostic phase with limited pressure (first pressure) to measure unlocking time and detect degradation, and an operational phase with full pressure for actual unlocking. This segmentation allows the system to prioritize detection without compromising the speed requirement for actual unlocking operations.
2Reliability
If pressure is limited for degradation detection, then detection capability is improved, but unlocking performance deteriorates
Solution Approach 1:
The system dynamically adjusts the pressure level based on the operational context. During diagnostic phases, it uses a lower first pressure to safely measure unlocking time and detect degradation. When actual unlocking is required, it switches to full operating pressure to ensure rapid unlocking performance. This dynamic adaptation resolves the contradiction between detection capability and unlocking performance.
3Reliability
If maintenance is performed frequently to prevent failure, then reliability is improved, but productivity deteriorates
Solution Approach 1:
The system implements feedback by continuously monitoring the unlocking time during pressure applications. When the measured unlocking time exceeds a predetermined threshold, the system generates a maintenance alert. This feedback mechanism allows maintenance to be performed only when actually needed, rather than on a fixed frequent schedule, thus improving productivity while maintaining reliability.
Solution Approach 2:
The system performs self-diagnosis by automatically measuring unlocking time and comparing it against thresholds to determine when maintenance is needed. This self-service capability eliminates the need for frequent scheduled maintenance inspections, allowing the system to monitor its own condition and request maintenance only when degradation is detected.
4Measurement precision
If observation frequency is increased to detect degradation, then measurement precision is improved, but device complexity deteriorates
Solution Approach 1:
The system changes the pressure parameter from full pressure to a limited first pressure during diagnostic operations. This parameter change allows sufficient time to measure unlocking time with adequate precision while avoiding the need for high-frequency observations. The predetermined time interval is set based on the expected range of unlocking times, providing precise degradation detection without excessive computational load.
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
Enables early detection of degraded unlocking performance in latching mechanisms, preventing latent failures by scheduling maintenance only when necessary, thus optimizing maintenance frequency and reducing the load on the computer system.
Implementation Method 1
the pressure build-up rate of a hook-type cylinder is generally very high (greater than 1000 bar per second). This is due to the small volume of fluid compressed by the piston
Implementation Method 2
A hydraulic supply circuit for a cylinder is known, the circuit including a delay valve
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
The invention relates to a method for diagnosing a state of deterioration of an uplock comprising an unlocking actuator 12, 22 provided with a hydraulic cylinder (Ve), the method comprising the following steps: • a) supplying the cylinder with pressurised fluid with an evolution law according to which the pressure of the fluid is, for a predetermined period (T), equal to a predetermined pressure (Pii m) lower than full pressure (Ps), and subsequently equal to full pressure; • b) determining a time of deactivation of the uplock and comparing it with the time when the predetermined time period ends; • c) deducing therefrom a state of deterioration of the uplock. The present invention also relates to a hydraulic circuit for supplying a cylinder and thereby enabling such a method to be implemented.