Electro-Hydrostatic Actuator Snubbing Mechanism for Landing Gear
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Solution Overview
Problem
Conventional hydrostatic actuators experience energy inefficiency and risk of equipment failure due to excess fluid circulation during snubbing actions, leading to increased temperatures and potential breakage, especially in airplane landing gear systems, where fuel consumption and heat management are critical.
Innovation Solution
An electro-hydrostatic actuator with a motor and pump system that adjusts the number of revolutions based on calculated load torque to control fluid flow, reducing energy waste and preventing overheating by managing the snubbing mechanism's impact on the piston and cylinder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the running amount of fluid is temporarily decreased during snubbing action, then the travelling speed of the piston is reduced and impact is relaxed, but the fluid flowing into the actuator gets highly pressurized causing breakage failure of related equipments
Solution Approach 1:
A snubbing piston is introduced as an intermediary element between the main piston and the cylinder bottom. This snubbing piston creates a buffering fluid chamber that mediates the fluid flow during snubbing action, allowing controlled discharge through an orifice to reduce piston speed without causing excessive pressure buildup that would lead to equipment failure
Solution Approach 2:
The system changes the flow parameters by introducing a restricted orifice in the snubbing mechanism. This orifice controls the discharge rate of fluid during snubbing action, modifying the fluid flow parameters to achieve both impact reduction and pressure control, preventing breakage failure of related equipments
2Reliability
If a relief valve is arranged in the hydrostatic circuit to maintain pressure, then equipment breakage is prevented, but energy is wasted through excess fluid circulation and temperature increases
Solution Approach 1:
The snubbing piston and buffering fluid chamber are activated in advance during the snubbing action to control fluid discharge before excessive pressure buildup occurs. This preliminary action prevents the need for relief valve operation, avoiding the energy waste and temperature increase that would result from excess fluid circulation through the relief valve
Solution Approach 2:
The system converts the potentially harmful effect of fluid compression during snubbing into a beneficial controlled discharge mechanism. The snubbing piston utilizes the pressurized fluid to drive controlled discharge through the orifice, transforming the harmful pressure buildup into a useful speed-control mechanism that prevents both impact damage and energy waste
3Speed
If the piston travelling speed is reduced by narrowing fluid path, then impact at retracted and extended positions is relaxed, but the fluid flow restriction causes highly pressurized fluid and potential equipment failure
Solution Approach 1:
The snubbing piston acts as an intermediary that creates a dedicated buffering fluid chamber with a controlled orifice. This intermediary structure allows speed reduction through restricted discharge while maintaining pressure control, preventing the excessive pressure buildup that would occur with direct fluid path narrowing
Solution Approach 2:
The fluid chamber is segmented into a buffering fluid chamber by the snubbing piston. This segmentation allows independent control of fluid discharge through the orifice, enabling speed reduction without proportionally increasing pressure, as the segmented chamber provides a controlled release mechanism
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 approach enhances energy efficiency during snubbing actions, reduces the risk of equipment failure by minimizing temperature increases, and improves fuel consumption and maintenance efficiency in airplane landing gear operations.
Implementation Method 1
a pump (19) for supplying fluid according to the rotation of the motor (18)
Implementation Method 2
a running amount of fluid into and from the cylinder is decreased by narrowing down fluid path
Implementation Method 3
a relief valve or the like is arranged in a hydrostatic circuit, so that the pressure of the fluid flowing into the actuator is maintained to not more than a predetermined value
Data Source
Figure 1
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AI summary
The present invention is to provide an electro hydrostatic actuator with a damping mechanism including a cylinder type actuator main body (1), a piston (2) having a piston rod, the piston slidingly moving in a cylinder of the actuator main body, a motor (18), a pump (19) for supplying fluid according to the rotation of the motor, a mechanism for adjusting a running amount of the fluid into and from the cylinder according to the motion of the piston, and a reservoir (8) for adjusting the supply of the fluid corresponding to a volume difference generated according to the motion of the piston, and a controller (17) which controls the number of revolutions of the motor according to the calculated load torque, and a damping control method used for this. An electro hydrostatic actuator of realizing a damping mechanism capable of increasing energy efficiency, when used for a landing gear retraction/extension device of an airplane, can be provided.