Miniature Bi-Directional Gear Pump With Pressure Compensation
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Solution Overview
Problem
Electro Mechanical Actuation Systems (EMAS) face issues such as jamming, wear in gears, and reduced power density, limiting their use in applications like aircraft flight controls, where they are often used only as backups due to these limitations and the need for additional components like gearboxes that increase volume and weight.
Innovation Solution
A compact Electro-Hydraulic Actuator (EHA) system incorporating a miniaturized bi-directional gear pump with a pressure compensation system to enhance energy efficiency and durability, designed to combine the power-to-weight advantages of hydraulic systems with the control ease of electric systems, using a simulation model for optimization and experimental verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If Electro Mechanical Actuation Systems (EMAS) are used to reduce weight, then weight is reduced, but power density decreases and reliability deteriorates due to jamming and wear
Solution Approach 1:
The patent employs a hydraulic pump driven by an electric motor to create an electro-hybrid actuation system. The hydraulic mechanism provides high power density and reliability through fluid power transmission, eliminating the jamming and wear issues of pure mechanical systems while maintaining the weight advantages of electric drive.
Solution Approach 2:
The invention merges electric motor technology with hydraulic actuation in a compact integrated unit. The electric motor drives a hydraulic pump that powers the actuator, combining the advantages of both systems: the weight and control benefits of electric systems with the power density and reliability of hydraulic systems.
2Force
If a gearbox is added to EMAS to reduce actuating torque, then torque is reduced permitting smaller motors, but volume and weight increase
Solution Approach 1:
The patent uses a hydraulic transmission system instead of a mechanical gearbox. The hydraulic pump and actuator provide torque multiplication through fluid pressure, achieving the same torque reduction effect without the bulk and weight of gear teeth and housing.
Solution Approach 2:
The system changes the operating parameters by using high-pressure hydraulic fluid to transmit and multiply force. This allows torque to be adjusted by controlling fluid pressure rather than mechanical gear ratios, providing a more compact solution.
3Force
If a high reduction ratio gearbox is used in EMAS, then actuating torque is reduced, but dynamic behavior deteriorates due to over-perceived inertia
Solution Approach 1:
The hydraulic system provides direct coupling between the motor and actuator through fluid pressure, eliminating the inertia effects of mechanical gear trains. The hydraulic fluid transmits force instantaneously, improving dynamic response while maintaining torque multiplication.
4Productivity
If fixed displacement pump design is used in EHA, then flow is controlled by motor speed, but energy efficiency decreases due to internal lubricating gaps
Solution Approach 1:
The patent implements a pressure compensation mechanism that dynamically adjusts the pump's internal clearances based on operating pressure. This minimizes leakage through lubricating gaps while maintaining the simplicity of fixed displacement pump design, thereby improving energy efficiency without sacrificing flow control capability.
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 EHA system offers superior energy efficiency and reduced noise emissions, addressing the limitations of EMAS by providing a reliable and efficient actuation solution for applications like aircraft systems, with improved durability and reduced volume and weight compared to traditional hydraulic systems.
Implementation Method 1
positive displacement pumps, and in particular to a gear pump useful in an actuation system
Implementation Method 2
pair of rotatable intermeshed gears
Implementation Method 3
pressure compensation system to minimize power losses associated with the internal lubricating gaps
Implementation Method 4
brushless electric motor
Data Source
AI summary
Methods and apparatus pertaining to positive displacement pumps, and further to hydraulic actuation systems. In some embodiments the pumps are gear pumps with bi-directional operation. In some embodiments the actuation system includes a motor-driven, reversible operation gear pump providing fluid under pressure to a rod and cylinder.