Linear Actuator Hydraulic Control With Variable-Speed Pump Feedback
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Solution Overview
Problem
Conventional hydraulic systems in industrial machines operate at constant pump speed, leading to inefficiency, increased temperature, and complexity, with open-loop systems prone to cavitation and reliability issues due to the lack of precise control over flow and pressure.
Innovation Solution
A fluid system with a linear actuator assembly featuring a variable-speed and/or variable-torque pump and proportional control valve assembly, where a controller concurrently adjusts the prime mover speed and control valve opening to precisely control flow and pressure, forming a closed-loop system for improved efficiency and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the hydraulic pump runs at constant full speed to ensure adequate fluid pressure, then the system reliability is improved, but the energy consumption increases and efficiency decreases
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 demands. The controller receives feedback from sensors monitoring flow and pressure, then modulates the prime mover speed accordingly, replacing constant-speed operation with adaptive variable-speed control to optimize energy efficiency while maintaining reliability.
Solution Approach 2:
The system incorporates sensors that continuously monitor hydraulic fluid flow and pressure, feeding this information back to the controller. The controller processes this feedback and adjusts the prime mover speed in real-time, creating a closed-loop control system that maintains adequate pressure and flow while minimizing energy consumption by avoiding unnecessary full-speed operation.
2Reliability
If the hydraulic pump runs at constant full speed to ensure adequate fluid pressure, then the system reliability is improved, but the temperature of hydraulic fluid increases
Solution Approach 1:
By implementing variable-speed control of the hydraulic pump based on actual system demands, the system avoids excessive energy input that would generate unnecessary heat. The dynamic adjustment of pump speed ensures pressure is maintained only when needed, reducing continuous full-speed operation and thereby minimizing heat generation in the hydraulic fluid.
Solution Approach 2:
Temperature monitoring and pressure feedback mechanisms allow the controller to adjust pump speed to maintain pressure without excessive energy input. When pressure demands are met at lower speeds, the system reduces pump speed, thereby reducing energy dissipation as heat and controlling hydraulic fluid temperature while maintaining system reliability.
3Measurement precision
If directional flow control valve is used to control flow rate, then the flow control precision is improved, but the device complexity increases
Solution Approach 1:
The patent replaces traditional mechanical directional flow control valves with an electronic control system that uses sensors and a controller to regulate pump speed. This substitution of mechanical valve-based flow control with electronic speed control achieves precise flow regulation while reducing the number of mechanical components, thereby simplifying the overall system architecture.
Solution Approach 2:
Instead of using mechanical valves to change flow direction and rate, the system changes the operating parameters of the pump itself by varying its speed electronically. This parameter-based control approach achieves precise flow control through electronic modulation of pump performance characteristics rather than through complex mechanical valve arrangements.
4Reliability
If open-loop system is used with fluid reservoir to prevent cavitation, then the cavitation risk is reduced, but the system size and weight increase
Solution Approach 1:
The closed-loop feedback system monitors pressure and flow conditions in real-time, allowing the controller to adjust pump speed to prevent cavitation conditions. This active control approach replaces the need for large fluid reservoirs that were required in open-loop systems to passively prevent cavitation, thereby reducing system weight and size while maintaining cavitation prevention capability.
Solution Approach 2:
By dynamically adjusting pump speed based on feedback from pressure and flow sensors, the system actively prevents cavitation conditions rather than relying on static design features like large reservoirs. This dynamic control enables compact system design without sacrificing cavitation protection.
Data Source
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Figure 2A
AI summary
A linear actuator system includes a linear actuator and at least one proportional control valve and at least one pump connected to the linear actuator to provide fluid to operate the linear actuator. The at least one pump includes at least one fluid driver having a prime mover and a fluid displacement assembly to be driven by the prime mover such that fluid is transferred from the pump inlet to the pump outlet. The linear actuator system also includes a controller that establishes at least one of a speed and a torque of the at least one prime mover and concurrently establishes an opening of the at least one proportional control valve to adjust at least one of a flow and a pressure in the linear actuator system to an operational set point.