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An Electrohydraulic Load Sensing System based on flow/pressure switched control for mobile machinery
Min Cheng1, Junhui Zhang2, Bing Xu2
1State Key Laboratory of Mechanical Transmissions, Chongqing University, Chongqing, China.
ISA Transactions
|June 26, 2019
Summary
This study introduces an Electrohydraulic Load Sensing (ELS) system that improves mobile machinery control by reducing pressure impacts and energy consumption. The novel switched control strategy ensures fast response and good damping, outperforming existing Electrohydraulic Flow Matching (EFM) systems.
Area of Science:
- Mechanical Engineering
- Control Systems Engineering
- Fluid Power Systems
Background:
- Existing load sensing systems in mobile machinery exhibit slow response and oscillation.
- Electrohydraulic Flow Matching (EFM) systems offer better controllability but face flow mismatch issues, causing pressure impacts and inefficiency.
Purpose of the Study:
- To propose and validate a novel Electrohydraulic Load Sensing (ELS) system with switched flow/pressure control.
- To enhance controllability and reduce flow mismatches in mobile machinery hydraulic systems.
- To improve energy efficiency and stability compared to EFM systems.
Main Methods:
- Developed an ELS system utilizing flow/pressure switched control for pump displacement.
- Implemented flow feedforward and pressure feedback controllers for precise flow requirement and pressure margin management.
- Established a system linearization model and conducted theoretical stability analysis for flow, pressure, and switched control modes.
- Constructed a test rig using a converted hydraulic excavator to experimentally validate the controller's effectiveness.
Main Results:
- The proposed ELS system successfully avoided pressure impacts associated with flow mismatches.
- Significant reduction in energy consumption was achieved compared to the EFM system.
- The velocity performance of the ELS system remained consistent with the EFM system, preserving controllability.
- Stability analysis confirmed reliable performance during transitions between flow and pressure control modes.
Conclusions:
- The Electrohydraulic Load Sensing (ELS) system with switched control offers a superior alternative to existing load sensing and EFM systems for mobile machinery.
- This approach effectively mitigates pressure impacts and enhances energy efficiency without compromising dynamic performance or controllability.
- The findings provide a foundation for developing more robust and efficient hydraulic control systems in mobile applications.
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