Linear Actuator Assembly With Closed-Loop Hydraulic Pressure Control
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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 that are 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, controlled by a controller to concurrently adjust the speed/torque of the pump and the opening of the control valve, forming a closed-loop system for precise control of flow and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the hydraulic pump is run at constant full speed to ensure adequate fluid pressure, then the system maintains sufficient pressure for all operations, but the system efficiency decreases and energy is wasted when load is only at 50%
Solution Approach 1:
The patent applies dynamics by transitioning from a static constant-speed pump operation to a dynamic variable-speed pump operation. The pump speed is continuously adjusted based on real-time load demands and system pressure 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 feedback control through pressure sensors that continuously monitor system pressure and feed this information back to the pump controller. The controller adjusts the pump speed based on this feedback signal, reducing speed when pressure is sufficient and increasing speed when additional pressure is needed, thus optimizing energy consumption while maintaining pressure requirements.
2Stress or pressure
If the hydraulic pump is run at constant full speed, then adequate fluid pressure is always available, but the hydraulic fluid temperature increases
Solution Approach 1:
By dynamically adjusting pump speed to match actual load requirements, the system reduces unnecessary pumping action that generates heat. When full speed is not needed for maintaining pressure, the pump operates at lower speeds, significantly reducing the mechanical energy converted to heat and thereby controlling hydraulic fluid temperature.
3Speed
If directional flow control valves are used to control flow rate, then flow control is achieved, but the system complexity increases and additional hydraulic fluid is required
Solution Approach 1:
The patent extracts the flow control function from separate mechanical directional flow control valves and integrates it into the electrical control system. By using an electric motor with variable speed control to drive the pump, the system eliminates the need for complex hydraulic flow control valves, reducing system complexity and the amount of hydraulic fluid required for valve operation.
Solution Approach 2:
The patent replaces the mechanical hydraulic flow control valve system with an electrical control system that regulates pump speed. This substitution eliminates the need for additional hydraulic circuits and valves dedicated to flow control, simplifying the overall system architecture and reducing hydraulic fluid requirements.
4Stability of the object's composition
If the hydraulic pump inertia is high, then the pump is stable during operation, but the pump cannot respond precisely to changes in flow and pressure demand
Solution Approach 1:
The patent employs feedback control where pressure sensors continuously monitor system pressure and flow conditions, and this information is fed back to the pump controller. The controller rapidly adjusts pump speed in response to these feedback signals, enabling precise control of flow and pressure despite the pump's inherent inertia, as the control system can anticipate and respond to load changes.
Solution Approach 2:
By implementing dynamic speed control with rapid response capability, the system overcomes the limitation of pump inertia. The variable speed drive can quickly adjust the pump operating point in response to changing demands, providing precise flow and pressure control while maintaining operational stability through continuous adaptation rather than relying on static high-inertia characteristics.
5Device complexity
If open-loop hydraulic systems are used, then the system is simpler to implement, but the system is prone to cavitation and reliability issues
Solution Approach 1:
The patent implements a closed-loop control system where pressure sensors provide continuous feedback on system pressure conditions to the pump controller. This feedback enables the controller to anticipate cavitation risks by monitoring pressure drops and adjusting pump speed proactively, maintaining reliable operation and preventing cavitation damage while keeping the control architecture relatively simple.
Data Source
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.