Thrust Reverser Hydraulic Valve for Impact Control
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Solution Overview
Problem
Aircraft thrust reverser systems face challenges with sudden changes in load during deployment and stow operations, leading to potential damage from aerodynamic forces, which existing systems fail to adequately manage, resulting in excessive wear and impact velocities.
Innovation Solution
A hydraulic valve system that controls fluid flow through the actuator, varying fluid flow based on the actuator's position to resist assistive aerodynamic loads and soften impacts, using a geometric profile to provide preconfigured variations in fluid flow rates and proportional movement of the valve slide to manage force changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic actuators are used to move transcowls during deployment and stow operations, then the thrust reverser system can effectively reverse airflow, but sudden changes in aerodynamic forces cause excessive wear and impact damage
Solution Approach 1:
The patent applies beforehand cushioning by introducing a hydraulic valve system that provides progressive flow restriction before the transcowl reaches end-of-travel positions. The valve creates increasing backpressure on the hydraulic fluid as the transcowl approaches deployment or stow limits, effectively cushioning the impact before it occurs. This prevents sudden shock loads and excessive wear on the actuator and transcowl components during normal operation.
Solution Approach 2:
The patent implements parameter changes by dynamically varying the hydraulic fluid flow rate through the actuator based on the transcowl position. The hydraulic valve adjusts the flow restriction parameter progressively as the transcowl moves toward end positions, changing the hydraulic resistance to match the varying aerodynamic loads. This controlled parameter modification smooths the deployment and stow operations, reducing impact forces and wear while maintaining operational reliability.
2Productivity
If conventional hydraulic control systems are used, then the system structure remains simple, but the system cannot provide fine resolution control of reverser velocity
Solution Approach 1:
The patent applies dynamics by making the hydraulic valve flow restriction characteristic position-dependent rather than fixed. The valve is designed with a progressive flow restriction feature that automatically adjusts the hydraulic resistance based on the transcowl position during deployment and stow operations. This dynamic adaptation provides fine resolution velocity control throughout the travel range without requiring complex external control systems, achieving precise speed regulation through the inherent mechanical-hydraulic coupling.
Solution Approach 2:
The patent implements self-service by designing the hydraulic valve to automatically regulate fluid flow based on the transcowl position without requiring external sensors or active control elements. The progressive flow restriction feature is mechanically integrated with the actuator system, allowing the valve to self-adjust the hydraulic resistance as the transcowl moves. This self-regulating mechanism achieves fine resolution velocity control while minimizing additional system complexity and control electronics.
3Productivity
If electrohydraulic servovalves are used to control fluid flow, then fine resolution velocity control is achieved, but system cost and complexity increase significantly
Solution Approach 1:
The patent applies mechanics substitution by replacing the electrohydraulic servovalve with a mechanically actuated hydraulic valve featuring progressive flow restriction. Instead of using electronic sensors, motors, and complex control circuits to regulate fluid flow, the invention uses a mechanically integrated valve design where the transcowl position directly controls the flow restriction through mechanical coupling. This substitution maintains fine resolution velocity control capability while dramatically reducing system complexity and cost by eliminating electronic control components.
Solution Approach 2:
The patent implements copying by creating a simplified mechanical replica of the complex electrohydraulic control function. The progressive flow restriction valve replicates the velocity control capability of an electrohydraulic servovalve through purely mechanical means, using the actuator's own motion to regulate fluid flow. This mechanical copy achieves the same control precision without requiring expensive electronic components, reducing system complexity while maintaining productivity.
Data Source
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Figure 5A
AI summary
The subject matter of this specification can be embodied in, among other things, a turbofan engine assembly includes a engine, a nacelle defining a generally forward-to-aft bypass air flow path, a thrust reverser comprising a first movable element, movable to and from a reversing position where at least a portion of the bypass air flow is reversed, a hydraulic actuator coupled to the first movable element to move the first movable element into and out of the reversing position, and a second moveable element, configured to move in synchronicity with the first moveable element, a first hydraulic valve operable to control a flow of hydraulic fluid for actuation of the hydraulic actuator, a second hydraulic valve operably coupled to the second moveable element and moveable between a restricted condition wherein the flow of hydraulic fluid is restricted, and a permit condition wherein the flow of hydraulic fluid is permitted.