Electro-Hydrostatic Actuation with Leakage Pump for High-Speed Stability
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Solution Overview
Problem
Electro-hydrostatic actuation systems face instability and pressure drops at high speeds due to the need for large hydro-accumulators, which compromise structural stability and compactness, especially in self-contained axes where pressure differences limit the accumulator's size and efficiency.
Innovation Solution
Incorporating a leakage branch with an additional pump connected to the low-pressure section of the main pump, along with a flushing branch and pressure-controlled valves, to manage hydraulic liquid flow and pressure, allowing for higher operational speeds and reduced accumulator size while maintaining system stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If large hydro-accumulators are used to supply compensatory aid in pressure drops, then system stability is improved, but structural stability and compactness deteriorate
Solution Approach 1:
The patent divides the single accumulator system into two separate accumulators: a first accumulator for the low-pressure circuit and a second accumulator for the high-pressure circuit. This segmentation allows each accumulator to be optimized for its specific pressure range, reducing the total volume required while maintaining system stability during pressure drops.
Solution Approach 2:
The patent changes the pressure parameter by introducing a second accumulator operating at high pressure (above 100 bar) compared to the first accumulator at low pressure. This parameter change allows the high-pressure accumulator to provide compensatory volume with much smaller size, resolving the contradiction between stability and compactness.
2Volume of moving object
If high pressure is maintained in the low-pressure section, then accumulator size is reduced, but operational speed is limited due to pressure difference constraints
Solution Approach 1:
The patent segments the pressure management into two independent circuits with separate accumulators, allowing the low-pressure circuit to operate at higher baseline pressure without compromising the high-pressure circuit's operational range, thereby enabling higher speeds.
Solution Approach 2:
The second high-pressure accumulator acts as an intermediary that supplies hydraulic fluid to the low-pressure circuit during high-speed operations, enabling the low-pressure section to maintain higher pressure while still supporting increased operational speeds.
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 configuration enables the electro-hydrostatic actuation system to operate at higher speeds with improved controllability and reduced pressure peaks, enhancing the system's efficiency and compactness by maintaining optimal pressure differences within the hydraulic circuit.
Implementation Method 1
an additional pump is arranged on the leakage branch
Implementation Method 2
a leakage branch, connecting the hydraulic leakage outlet of the low-pressure section of the housing of the main pump to the low-pressure circuit
Data Source
AI summary
An electro-hydrostatic actuation system and a method for driving a hydraulic actuator, e.g. a hydraulic cylinder, are described, wherein the system comprising a leakage branch, and wherein preferably an additional pump is arranged. The system further comprises a source for providing hydraulic liquid; a high-pressure circuit to direct the hydraulic liquid to a hydraulic actuator, such as e.g. a hydraulic cylinder; a low-pressure circuit having several branches; a main pump for hydraulic liquid arranged in the high-pressure circuit, comprising a housing having a high-pressure section and a low-pressure section, separated by gap sealings, wherein the high-pressure section comprises a first outlet and a second outlet to provide the hydraulic liquid flow in the high-pressure circuit; and wherein the low- pressure section comprises a leakage outlet; an electric motor driving the main pump.