Hydraulic Actuator End Stop Valve for Parasitic Flow Cutoff
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Solution Overview
Problem
Aircraft hydraulic actuator systems face challenges in efficiently managing parasitic flow, particularly during engine start and low pump capability conditions, which affects system sizing and performance.
Innovation Solution
The system incorporates a hydraulic actuator with a primary piston and a secondary piston-based actuator valve that transitions between open and closed flow states, controlled by a biasing element and an electrohydraulic servo valve, allowing for adjustable pressure distribution and reduced parasitic flow through an on/off flow control mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydraulic actuator system operates during engine start and low pump capability conditions, then the system must maintain basic actuation functionality, but parasitic flow increases and reduces system efficiency
Solution Approach 1:
The end stop valve is pre-configured to automatically activate when the piston reaches the end of its stroke, preventing parasitic flow before it can occur. This preliminary action ensures that during low pump capability conditions, the system maintains actuation functionality while minimizing energy loss through parasitic flow.
Solution Approach 2:
The end stop valve acts as an intermediary component between the piston and the hydraulic fluid. It mediates the flow by closing at the end of the stroke, preventing direct parasitic flow paths while maintaining the necessary pressure for reliable actuation functionality during challenging operating conditions.
2Temperature
If the actuator system allows continuous fluid flow for cooling, then cooling effectiveness is maintained, but parasitic flow increases during low pump capability conditions
Solution Approach 1:
The end stop valve creates periodic flow interruption by closing at the end of each piston stroke. This periodic action allows the system to maintain cooling effectiveness during extended operation while preventing continuous parasitic flow during low pump capability conditions, thereby improving overall system efficiency.
Solution Approach 2:
The end stop valve applies local flow control at the specific location where the piston reaches the end of its stroke. This localized quality control prevents parasitic flow in the cooling circuit during low pump capability conditions while maintaining cooling effectiveness where needed, optimizing the balance between temperature control and system efficiency.
3Temperature
If the system is designed to handle high pump capability conditions, then cooling flow is optimized, but the system becomes oversized for low pump capability conditions
Solution Approach 1:
The end stop valve introduces dynamic flow control that adapts to varying pump capability conditions. By automatically closing at the end of each stroke, it dynamically adjusts the cooling flow to match actual system needs, allowing the system to be properly sized for low pump capability conditions while still achieving optimized cooling flow when pump capability is high.
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 solution enables improved system efficiency by minimizing parasitic flow during low pump conditions and optimizing cooling flow at high temperatures, enhancing design optimization and performance across various operational conditions.
Implementation Method 1
the actuator valve includes a biasing element configured to bias the secondary piston into the open flow state
Implementation Method 2
when the primary piston is in a fully retracted state the piston head urges the secondary piston into a closed flow state
Implementation Method 3
A control element is configured to control a supply of pressure to each of the retract chamber and the extend chamber
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
Actuator systems (100) and methods of operation are disclosed. The systems include a hydraulic actuator (102) having a primary piston (104) having a piston head (112) arranged within a housing (106) defining retract and extend chambers (108, 110) on opposite sides of the piston head. A control element (118) is configured to control a supply of pressure to each of the retract and extend chambers. An actuator valve (124) is coupled to the housing and includes a secondary piston (126) that is biased into the retract chamber in an open flow state and when the primary piston is in a fully retracted state the piston head urges the secondary piston into a closed flow state. The actuator valve defines a flow chamber (132) where, in an open flow state, fluid can be passed through the flow chamber and in a closed flow state the fluid is prevented from passing through the flow chamber.