Aircraft Hydraulic Actuation Bypass Heating for Faster Landing Gear Retraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The retraction time of aircraft landing gear is significantly affected by the viscosity of hydraulic fluid, which increases with temperature drops, leading to reduced climb performance and maximum take-off weight.
Innovation Solution
A hydraulic actuation system with a bypass line containing a flow restrictor and a bypass valve, which opens only during take-off or landing procedures, allowing hydraulic fluid to flow through the flow restrictor and generate heat, reducing fluid viscosity and actuation time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the bypass valve is opened to allow hydraulic fluid to flow through the flow restrictor, then the hydraulic fluid temperature increases and viscosity decreases improving actuator response time, but heat is generated and energy is consumed
Solution Approach 1:
The bypass valve is opened in advance during take-off and landing procedures to pre-warm the hydraulic fluid before it is needed for critical actuator operations. This preliminary heating action ensures that when the actuators are needed, the fluid is already at optimal temperature, reducing response time without needing continuous heating.
Solution Approach 2:
The bypass valve operation is periodic rather than continuous - it is opened only during specific procedures (take-off and landing) when actuator performance is critical. This periodic operation reduces energy consumption by avoiding continuous heat generation while still maintaining fluid temperature during critical phases.
2Use of energy by moving object
If the bypass valve remains closed to prevent heat generation, then energy consumption is reduced, but the hydraulic fluid remains cold and viscous increasing actuator response time
Solution Approach 1:
The system performs preliminary warming of the hydraulic fluid by opening the bypass valve during take-off and landing procedures. This advance preparation ensures the fluid is warmed before critical actuator operations are needed, eliminating the trade-off between energy use and response time during these critical phases.
Solution Approach 2:
The system changes the operational parameters of the bypass valve based on flight phase - opening it during take-off and landing when actuator performance is critical, and closing it during other phases. This parameter change allows optimization of both energy consumption and response time by adapting to operational requirements.
3Loss of time
If the bypass valve is opened during flight before landing, then the hydraulic fluid is warmed reducing viscosity, but excess heat energy is generated and lost to the environment
Solution Approach 1:
The bypass valve operates periodically only during take-off and landing procedures rather than continuously during flight. This timing ensures heat is generated only when actuators are about to be used, preventing waste of heat energy during phases when actuators are not needed, while still achieving warm fluid for critical operations.
Solution Approach 2:
The hydraulic fluid is warmed in advance during take-off and landing procedures when actuators are about to be used. This preliminary warming action ensures optimal fluid temperature at the moment of need without generating excess heat that would be wasted during extended flight periods when actuators are idle.
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
The system efficiently reduces the time required to actuate the hydraulic actuator by warming the hydraulic fluid, thereby improving climb performance and allowing for increased maximum take-off weight without generating excess heat or losing heat to the environment.
Implementation Method 1
the flow restrictor being configured to restrict a rate of fluid flow through the bypass line... Flow of fluid through the flow restrictor generates heat in the fluid and its surroundings
Implementation Method 2
Flow of fluid through the flow restrictor generates heat in the fluid and its surroundings. Therefore, as the hydraulic fluid flows through the flow restrictor after the bypass valve has opened, the hydraulic fluid and its surroundings increase in temperature
Data Source
AI summary
A hydraulic actuation system for an aircraft. The system comprises: a hydraulic actuator comprising: a housing to accommodate hydraulic fluid; an extension chamber and a retraction chamber each defined by the housing; and a bypass line in fluid communication with the extension chamber and the retraction chamber, the bypass line comprising a flow restrictor and a bypass valve, the flow restrictor configured to restrict a rate of fluid flow through the bypass line; and a controller configured to receive a signal indicative that the aircraft is in a take-off or a landing procedure, to determine that the aircraft is performing the take-off or the landing procedure based on the signal, and to perform an operation to cause the bypass valve to open to allow the hydraulic fluid to flow through the bypass line only when the controller determines that the aircraft is performing the take-off or the landing procedure.