Electro-Hydraulic Power Unit With Variable Flow by Pressure Feedback
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Solution Overview
Problem
Hydraulic power units with constant speed electric motors and fixed displacement pumps waste energy by providing continuous fluid flow regardless of hydraulic system demand, leading to inefficiency and reduced system life due to excess power being dissipated as heat.
Innovation Solution
An electro-hydraulic power unit with a pressure sensor and controller that adjusts the speed of the electric motor based on hydraulic line pressure, varying fluid flow rate to match system demand, using either a fixed or variable displacement pump to optimize energy usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a constant speed electric motor and fixed displacement pump are used, then the power unit provides continuous fluid flow, but energy is wasted and system efficiency decreases
Solution Approach 1:
The patent applies dynamics by transitioning from a static constant-speed motor system to a dynamic variable-speed motor system. The electric motor speed is continuously adjusted based on real-time hydraulic system demand signals, allowing the pump output to match actual requirements. This dynamic adaptation eliminates continuous fluid flow when not needed, thereby reducing energy wastage while maintaining productivity when demand exists.
Solution Approach 2:
The patent implements parameter changes by varying the electric motor speed parameter in response to hydraulic system demand. Instead of operating at a fixed speed, the motor speed parameter is modulated based on feedback from the hydraulic circuit, enabling the system to provide variable fluid flow rates that match actual demand, thus improving energy efficiency without sacrificing productivity capability.
2Reliability
If the power unit provides continuous fluid flow regardless of demand, then fluid flow is always available, but excess power is dissipated as heat reducing system life
Solution Approach 1:
The patent employs feedback by continuously monitoring hydraulic system demand through pressure sensors and other detectors in the hydraulic circuit. This feedback information is used to adjust the electric motor speed in real-time, ensuring fluid flow is provided only when and to the extent needed. This eliminates continuous operation at full capacity, reducing heat generation from excess power dissipation and thereby extending power unit life while maintaining system availability when required.
Solution Approach 2:
The patent implements periodic action by activating fluid flow provision only during periods when hydraulic demand is detected. The system transitions from continuous operation to intermittent operation, where the motor runs at variable speeds or remains idle during low-demand periods. This periodic activation reduces cumulative operating hours and thermal stress on components, extending system life while ensuring availability during active periods.
3Loss of energy
If complicated components and complex controls are added to improve efficiency, then energy efficiency improves, but system cost and complexity increase
Solution Approach 1:
The patent applies universality by designing a control system that uses existing hydraulic circuit elements (valves, pressure lines, flow paths) to generate demand signals that directly control motor speed. Rather than adding dedicated sensors and complex electronics throughout the system, the existing hydraulic architecture is leveraged to provide both power transmission and control signaling functions, reducing overall system complexity while achieving energy efficiency.
Solution Approach 2:
The patent uses hydraulic pressure as an intermediary carrier to transmit demand information from the hydraulic circuit to the motor control system. Instead of requiring direct electronic sensing and complex signal processing, the hydraulic pressure variations themselves serve as the control signal, simplifying the interface between the power unit and control system while enabling efficient energy management.
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 solution enhances system efficiency by ensuring only the necessary fluid flow is provided, reducing energy wastage and extending the life of the power unit by dynamically adjusting output to meet demand.
Implementation Method 1
a pressure sensor mounted to the hydraulic line and configured to provide sensor information indicative of pressure level of fluid in the hydraulic line
Implementation Method 2
a pump coupled to, and driven by, the electric motor... configured to provide fluid flow to a hydraulic circuit
Data Source
AI summary
An example system includes an electric motor (102); a pump (104) coupled to the electric motor; a hydraulic circuit (108) fluidly-coupled to the pump and configured to receive fluid flow from the pump; a hydraulic line (110) fluidly-coupled to the hydraulic circuit, wherein the hydraulic circuit is configured to provide a fluid signal to the hydraulic line, wherein the fluid signal is indicative of a fluid flow demand of the hydraulic circuit; a pressure sensor (112) mounted to the hydraulic line and configured to provide sensor information indicative of pressure level of fluid in the hydraulic line; and a controller (114) configured to control a speed of the electric motor to vary fluid flow rate provided by the pump to the hydraulic circuit to meet the fluid flow demand based on the pressure level indicated by the sensor information.