Stability Analysis of a Load-Sensing Hydraulic System

The traditional load-sensing hydraulic system is an energy-saving fluid power transmission, which supply ''on-demand'' flow at a prescribed pressure margin greater than the highest load pressure of the system. In this paper, a novel loadsensing system that has a variable pressure margin through overriding differential pressure control via integrating an electro-proportional three-way type pressure reducing valve into the hydro-mechanical load-sensing valve is proposed. Also, a bond graph model taking into account the dynamic characteristics of load-sensing valve and load-sensing path is constructed, and three group experiments are performed to verify the validation of the model. Based on the bond graph model, a series of theoretical simulations are carried out to prove that the proposed Load-Sensing system enables a satisfactory balance between energy efficiency and rapid dynamic response over a wide range of operating conditions. In addition, due to overriding differential pressure control, mode selection and power limit regulation can also be achieved.

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“…In addition, the volumetric flow through the directional valve opening can be assessed using equation (6) Q…”

Section: Applications Discussionmentioning

confidence: 99%

Performances analysis of a novel load-sensing hydraulic system with overriding differential pressure control

Zhang

Tian

et al. 2016

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…Similarly, the common model for the displacement controller design and evaluation of the piston pump system [15][16][17][18][19] can be modeled as follows:…”

Section: Test Rigmentioning

confidence: 99%

“…They analyzed the stability of the load-sensing (LS) controlled variable displacement pump system and found that the LS systems are prone to oscillation or even unstable behavior, because the load dynamics and the pump dynamics become inherently heavily coupled through an LS mechanism [17][18][19]. Kim et al [20] used an electronic angle sensor and an acceleration sensor to measure the dynamic state of the swash plate of a modified high-bandwidth pump control system.…”

Section: Introductionmentioning

confidence: 99%

Investigation into the Effects of the Variable Displacement Mechanism on Swash Plate Oscillation in High-Speed Piston Pumps

2018

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High-speed, pressure-compensated variable displacement piston pumps are widely used in aircraft hydraulic systems for their high power density. The swash plate is controlled by the pressure-compensated valve, which uses pressure feedback so that the instantaneous output flow of the pump is exactly enough to maintain a presetting pressure. The oscillation of the swash plate is one of the major excitation sources in the high-speed piston pump, which may cause lower efficiency, shorter service life, and even serious damage. This paper presents an improved model to investigate the influence of the variable displacement mechanism on the swash plate oscillation and introduces some feasible ways to reduce oscillation of the swash plate. Most of the variable structural parameters of the variable displacement mechanism are taken into consideration, and their influences on swash plate oscillation are discussed in detail. The influence of the load pipe on the oscillation of the swash plate is considered in the improved model. A test rig is built and similarities between the experiments and simulated results prove that the simulation model can effectively predict the variable displacement mechanism state. The simulation results show that increasing the volume of the outlet chamber, the spring stiffness of the control valve, the action area of the actuator piston, and offset distance of the actuator piston can significantly reduce the oscillation amplitude of the swash plate. Furthermore, reducing the diameter of the control valve spool and the dead volume of the actuator piston chamber can also have a positive effect on oscillation amplitude reduction.

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“…The hydraulic valve-controlled systems have high response but low energy-efficiency. Some researches have focused on the improvement of energy-efficiency of the hydraulic-valve-controlled systems [2][3][4][5][6]. However, it is still lower than that of the hydraulic pump-controlled system [5][6].…”

Section: Introductionmentioning

confidence: 99%

A Comparison of an Ac-Servo Motor Driving Variable Rotational Speed and a Variable Displacement Pump-Controlled Systems for Velocity Control

Chiang

Chen

2008

Proceedings of the JFPS International Symposium on Fluid Power

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In the hydraulic servo control applications, hydraulic valve-controlled systems, which have a problem of low energy efficiency, are used mostly because of the high response characteristics. Hydraulic pump-controlled servo systems have high energy-efficiency. However, the conventional pump-controlled systems, which are altered by displacement via variable displacement pumps, have lower response. This paper aims to investigate the servo performance of the high response and high energy efficiency electro-hydraulic pump-controlled system driven by a variable rotational speed AC servo motor in comparison with the conventional pump-controlled systems which are altered by displacement via variable displacement pumps. For that, the control strategy, adaptive fuzzy sliding-mode controller (AFSMC) is introduced. The AFSMC can not only simplify the fuzzy rule base but also estimate the equivalent control force and online self-tune the rule base through the adaptive strategy. The developed high response variable rotational speed electro-hydraulic pump-controlled system controlled by AFSMC and the conventional variable displacement pump-controlled system (VDPCS) are implemented and verified experimentally for velocity control with various velocity targets and external loading conditions. Furthermore, the energy efficiencies of different experiments are analyzed and compared precisely by the power quality recorder used to measure the electrical power consumed by the AC servo motor.

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Stability Analysis of a Load-Sensing Hydraulic System

Cited by 25 publications

References 7 publications

Performances analysis of a novel load-sensing hydraulic system with overriding differential pressure control

Performances analysis of a novel load-sensing hydraulic system with overriding differential pressure control

Investigation into the Effects of the Variable Displacement Mechanism on Swash Plate Oscillation in High-Speed Piston Pumps

A Comparison of an Ac-Servo Motor Driving Variable Rotational Speed and a Variable Displacement Pump-Controlled Systems for Velocity Control

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