Electrohydrostatic Actuator Layout for Multi-Shaft Pressure Control
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Solution Overview
Problem
Electrohydrostatic actuator systems with multiple consumers face uncontrollable movement and high energy consumption when peak powers are required, as they typically require multiple actuators and a constant pressure system that is inefficient and sluggish in control.
Innovation Solution
An electrohydrostatic actuator system with a volume-variable or rotational-speed-variable hydro machine driven by an electric motor, featuring a main shaft and a secondary shaft, both hydraulically connected to a hydraulic accumulator, allowing for parallel operation using a single hydro machine, which reduces energy consumption and improves control by maintaining pressure through the accumulator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If multiple actuators are used to operate several consumers simultaneously, then each consumer can be controlled independently, but the system complexity and energy consumption increase significantly
Solution Approach 1:
The patent combines multiple actuator functions into a single hydro machine by using a common hydraulic circuit that distributes fluid to multiple consumers (main shaft and secondary shaft). This merging approach allows one hydro machine to control multiple consumers simultaneously, reducing the total number of actuators from multiple to one, while maintaining independent control capability through separate control valves for each consumer.
Solution Approach 2:
The single hydro machine is designed with multi-functionality to serve multiple consumers. The hydraulic circuit is configured to distribute hydraulic fluid to both the main shaft and secondary shaft, allowing one actuator to perform the work of multiple actuators. This universal design reduces system complexity while enabling independent operation of each consumer through dedicated control valves.
2Power
If a constant pressure system with accumulator is used to provide peak power, then sufficient power is available, but energy consumption increases and control becomes sluggish
Solution Approach 1:
The patent replaces the constant pressure system with a dynamic pressure system where the hydro machine adjusts its output based on actual demand. The variable displacement pump modifies hydraulic fluid delivery according to system needs, providing peak power only when required rather than maintaining constant high pressure. This dynamic approach reduces energy consumption by avoiding continuous high-pressure maintenance while still delivering sufficient peak power when consumers require it.
Solution Approach 2:
The system changes the pressure parameter dynamically rather than maintaining constant high pressure. The hydro machine with variable displacement pump adjusts pressure and flow rate according to the actual power demands of the consumers. This parameter change strategy allows the system to provide peak power when needed while reducing energy consumption during normal operation, eliminating the need for energy-intensive constant pressure maintenance.
3Power
If parallel pump units are used to operate multiple consumers, then power distribution is achieved, but the system becomes uncontrollable as volume flow takes the path of least resistance
Solution Approach 1:
The patent implements feedback control through separate control valves for each consumer (main valve for main shaft, secondary valve for secondary shaft). These valves monitor and regulate the hydraulic fluid flow to each consumer based on their actual power requirements. This feedback mechanism prevents the uncontrollable 'path of least resistance' behavior by actively managing flow distribution, ensuring each consumer receives appropriate power while maintaining overall system controllability.
Solution Approach 2:
The control valves act as intermediaries between the single hydro machine and the multiple consumers. Rather than allowing direct, uncontrolled flow distribution, the control valves mediate the hydraulic fluid delivery to each consumer, regulating flow and pressure according to demand. This intermediary control mechanism enables power distribution to multiple consumers while maintaining system controllability, preventing the chaotic flow distribution that occurs with parallel pump units.
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 efficient and controlled operation of multiple shafts with reduced energy consumption and device requirements, minimizing potential failures and costs by using a single hydro machine for both shafts, while maintaining pressure and preventing cavitation.
Implementation Method 1
a hydraulic accumulator, which is hydraulically connected to the first secondary hydraulic line in the area between the first chamber of the secondary shaft and the first secondary valve
Implementation Method 2
a volume-variable and/or rotational-speed-variable hydro machine, which is driven by an electric motor, for providing a volume flow of a hydraulic fluid
Implementation Method 3
the shafts of the actuator system according to the invention are movable, wherein the movement is preferably provided by hydraulic fluid entering or exiting the chambers and the pressure buildup or pressure reduction associated therewith
Data Source
AI summary
The electrohydrostatic actuator system according to the invention comprises a volume-variable and/or rotational-speed-variable hydro machine, which is driven by an electric motor, for providing a volume flow of a hydraulic fluid, and a main shaft which is movable by the hydraulic fluid and which has at least one first chamber, wherein the first chamber, with at least one first main hydraulic line and a first main valve, is hydraulically connected to the hydro machine via a connection line. The actuator system according to the invention further comprises a secondary shaft which is movable by the hydraulic fluid and which has at least one first chamber, wherein the first chamber, with at least one first secondary hydraulic line and a first secondary valve, is hydraulically connected to the hydro machine via a connection line. Furthermore, according to the invention, a hydraulic accumulator is hydraulically connected to the first secondary hydraulic line in the area between the first chamber of the secondary shaft and the first secondary valve.