Variable-Speed Hydraulic Pump Control for Precise Flow and Pressure
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Solution Overview
Problem
Conventional hydraulic systems in industrial applications face inefficiencies due to the inability to precisely control fluid flow and pressure, leading to increased energy consumption and reliability issues, particularly because they often operate at constant pump speeds and use complex open-loop systems susceptible to contamination and cavitation.
Innovation Solution
A hydraulic system employing a variable-speed and/or variable-torque pump in conjunction with proportional control valves and a controller to synchronize the operation of fluid drivers and control valves, enabling faster and more precise control of fluid flow and pressure, potentially transitioning to a closed-loop system for reduced accumulator sizes and lower cavitation risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a constant speed hydraulic pump is used to ensure adequate pressure, then system pressure is maintained, but energy efficiency deteriorates as the pump runs at full speed even when system load is only at 50%
Solution Approach 1:
The patent applies dynamics by transitioning from a constant speed pump to a variable speed pump that can adjust its rotational speed according to actual system demands. The controller dynamically modifies the pump speed based on feedback from sensors monitoring system pressure and flow requirements, allowing the pump to operate at optimal speeds rather than constantly at full speed, thereby improving energy efficiency while maintaining adequate pressure.
Solution Approach 2:
The patent implements parameter changes by varying the operational parameters of the hydraulic pump, specifically its speed and flow rate. The controller adjusts these parameters in real-time based on system conditions, enabling the pump to deliver precisely the amount of hydraulic fluid needed at the required pressure, thus avoiding energy waste from over-pumping while ensuring sufficient pressure for actuator operation.
2Measurement precision
If flow control devices are added to control fluid flow precisely, then flow control precision is improved, but device complexity increases due to additional hydraulic controls and components
Solution Approach 1:
The patent replaces complex mechanical hydraulic control systems with an electronically controlled variable speed pump system. Instead of using multiple hydraulic flow control valves and mechanical control circuits, the system uses a controller with electronic sensors and actuators that directly modulate the pump's speed and flow output, achieving precise flow control with simpler overall system architecture.
Solution Approach 2:
The variable speed pump serves multiple functions simultaneously: it acts as both the pressure source and the flow control device. By integrating the flow control capability into the pump itself through variable speed operation, the system eliminates the need for separate flow control devices, reducing overall device complexity while maintaining precise flow control through the controller's management of pump operational parameters.
3Reliability
If an open-loop system with large fluid reservoir is used, then cavitation prevention is improved, but system reliability deteriorates due to susceptibility to contamination and component damage in harsh environments
Solution Approach 1:
The patent implements feedback control by using sensors to monitor system conditions such as pressure, temperature, and fluid flow, and feeding this information back to the controller. The controller continuously adjusts the variable speed pump's operation based on this feedback, maintaining optimal parameters that prevent cavitation while minimizing the need for large fluid reservoirs. This closed-loop control enables reliable cavitation prevention in compact systems by responding dynamically to changing conditions.
4Measurement precision
If variable speed pump is used for precise flow control, then flow control precision is improved, but system complexity increases due to need for controller coordination of pump and control valves
Solution Approach 1:
The patent extracts the flow control function from separate hydraulic control valves and integrates it directly into the variable speed pump through electronic control. By removing the need for complex hydraulic control circuits and multiple control valves, the system achieves precise flow control through the controller's direct management of pump speed, simplifying the overall control system architecture while maintaining high precision.
Data Source
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AI summary
A fluid system includes a variable-speed and/or a variable-torque pump to pump a fluid, at least one proportional control valve assembly, an actuator that is operated by the fluid to control a load, and a controller that establishes a speed and/or torque of the pump and a position of the at least one proportional control valve assembly. The pump includes at least one fluid driver that provides fluid to the actuator, which can be, e.g., a fluid-actuated cylinder, a fluid-driven motor or another type of fluid-driven actuator that controls a load. Each fluid driver includes a prime mover and a fluid displacement assembly. The fluid displacement assembly can be driven by the prime mover such that fluid is transferred from the inlet port to the outlet port of the pump.