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 reduced reliability, particularly because of the complexity and open-loop nature of these systems, which results in larger accumulator sizes and a higher risk of pump cavitation.
Innovation Solution
A closed-loop fluid system utilizing 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, allowing for faster and more precise control of fluid flow and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a conventional hydraulic pump is run at full speed or constant speed to ensure adequate pressure, then the system maintains required pressure for flow control devices, 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 variable speed drive technology to the hydraulic pump, allowing the pump speed to dynamically adjust according to actual system load requirements. The controller receives feedback from sensors monitoring system pressure and flow demand, then modulates the pump motor speed accordingly. This dynamic adjustment enables the pump to operate at optimal speeds matching actual demand, eliminating the waste of running at full speed when load is only 50%, while still ensuring adequate pressure is maintained when needed.
2Use of energy by moving object
If the hydraulic pump speed is varied to control flow, then energy efficiency improves, but the inertia of the hydraulic pump makes it impractical to precisely control the flow in the system
Solution Approach 1:
The patent implements a closed-loop feedback control system that combines variable speed pump operation with electronic flow control. Sensors continuously monitor actual flow and pressure conditions, feeding this information back to the controller. The controller processes this feedback and adjusts the pump motor speed in real-time to achieve precise flow control despite pump inertia. This feedback mechanism enables accurate flow regulation by constantly comparing actual conditions with desired conditions and making corrective speed adjustments.
Solution Approach 2:
The patent replaces traditional mechanical flow control devices (such as throttle valves and flow control spools) with an electronic control system that regulates pump motor speed. Instead of using mechanical means to restrict flow after the pump generates it, the system uses electronic variable speed drives to control the pump's output directly. This substitution of mechanical flow control with electronic speed control eliminates the precision limitations imposed by pump inertia while maintaining energy efficiency.
3Ease of operation
If flow control devices are added to control flow, then flow control capability improves, but system complexity increases and additional hydraulic fluid is required
Solution Approach 1:
The patent extracts and eliminates traditional hydraulic flow control devices (throttle valves, flow control spools, and associated hydraulic circuits) from the system. Instead of adding these complex mechanical components, the invention uses the variable speed pump controller to directly regulate flow by adjusting pump output. This removal of unnecessary flow control hardware simplifies the overall system architecture, reduces the number of moving parts, and eliminates the need for additional hydraulic fluid required by traditional flow control devices.
Solution Approach 2:
The patent makes the pump motor and its variable speed drive serve multiple functions: they not only generate hydraulic pressure and flow but also directly control flow rate through speed modulation. The single variable speed pump system performs what would traditionally require multiple dedicated components (pressure relief valve, flow control valve, accumulators). This multi-functionality consolidates the system into fewer components, reducing overall complexity while maintaining full flow control capability.
4Reliability
If an open-loop system with large fluid reservoir is used, then temperature control and adequate fluid supply are maintained, but additional components like connecting shafts, hoses, pipes, and fittings are required which increase complexity and susceptibility to contamination
Solution Approach 1:
The patent merges the pump, motor, variable speed drive, and control electronics into a tightly integrated unitized system. The pump and motor are coupled directly without external connecting shafts, and the control electronics are housed within the pump assembly. This consolidation eliminates the need for separate connecting shafts, hoses, pipes, and fittings that would be required in an open-loop distributed system. The integrated design maintains all necessary functions (fluid supply, temperature control, flow regulation) while dramatically reducing the number of external connections and potential contamination points.
Solution Approach 2:
The patent introduces an electronic control system as an intermediary between the operator and the hydraulic system. This electronic mediator receives input signals, processes them through the variable speed drive controller, and translates them into precise pump speed adjustments. This electronic intermediary eliminates the need for complex mechanical linkages and hydraulic control lines that would connect separate system components. The electronic signal transmission through wires and circuits replaces what would otherwise require numerous mechanical and hydraulic connections, reducing complexity and contamination risk.
Data Source
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.