Independent volume-in and volume-out control of an open circuit pump-controlled asymmetric cylinder system

Yao, Jianyong; Wang, Pei; Cao, Xiaoming; Wang, Zhuo

doi:10.1631/jzus.a1600780

Cited by 14 publications

(8 citation statements)

References 18 publications

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“…The open-circuit solution (Figure 8a) has been presented in [81,88] investigated this concept in a 0.6 MN forging press. A decentralized position and rod side pressure chamber control method has been adopted.…”

Section: Class D-single Constant-speed Prime Mover and Multiple Pumpsmentioning

confidence: 99%

Classification and Review of Pump-Controlled Differential Cylinder Drives

et al. 2019

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Pump-controlled hydraulic cylinder drives may offer improved energy efficiency, compactness, and plug-and-play installation compared to conventional valve-controlled hydraulic systems and thus have the potential of replacing conventional hydraulic systems as well as electro-mechanical alternatives. Since the late 1980s, research into how to configure the hydraulic circuit of pump-controlled cylinder drives has been ongoing, especially in terms of compensating the uneven flow requirements required by a differential cylinder. Recently, research has also focused on other aspects such as replacing a vented oil tank with a small-volume pressurized accumulator including the consequences of this in terms of thermal behavior. Numerous references describe the advantages and shortcomings of pump-controlled cylinder drives compared to conventional hydraulic systems or electro-mechanical drives. This paper presents a throughout literature review starting from the earliest concepts based on variable-displacement hydraulic pumps and vented reservoirs to newer concepts based on variable-speed electric drives and sealed reservoirs. By classifying these drives into several proposed classes it is found that the architectures considered in the literature reduce to a few basic layouts. Finally, the paper compares the advantages and shortcomings of each drive class and seek to predict future research tasks related to pump-controlled cylinder drives. IntroductionWith an increased industrial focus on energy efficiency, plug-and-play installation, and compactness, conventional valve-controlled hydraulic cylinder drives are increasingly being replaced by electro-mechanical alternatives, such as roller or ball screws [1], especially for small power classes. This happens despite the well-known advantages of hydraulic linear actuation such as large force/power densities, reliability, and robustness. Hydraulic actuation is, however, still the preferred solution for many applications such as industrial presses, large mobile machinery, crane manipulators, primary aircraft control etc. [2][3][4]. Among other reasons this is due to certain limitations for the electro-mechanical alternatives, such as limited reliability (e.g., shock loads damage), the difficulties of implementing overload/failure protection and/or limited force capabilities [5][6][7]. To strengthen the position regarding these applications and to make hydraulic cylinder drives competitive with electro-mechanical drives for low power applications, there is a need to enhance both the energy efficiency and the overall flexibility of hydraulic cylinder drives.The flexibility of a hydraulic system may be related to how power is being distributed between the prime mover and the actuator(s). As illustrated in Figure 1, at least three different power distribution topologies exist: hydraulic, mechanical, and electrical distribution.

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Section: Class D-single Constant-speed Prime Mover and Multiple Pumpsmentioning

confidence: 99%

Classification and Review of Pump-Controlled Differential Cylinder Drives

et al. 2019

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“…PCDS is mainly composed of pump control loop [21], valve control loop and oil-addition loop, as shown in Figure 1. In the pump control loop, two-way quantitative gear pump 7 is drive by servo motor 8.1 to realize bi-directional rotation and then control the action of asymmetrical cylinder 1.…”

Section: Design Of Pcdsmentioning

confidence: 99%

“…The inlet flow of the rodless cavity of asymmetrical cylinder and the corresponding volume are shown as follows: (21) The oil return flow of the rod cavity of asymmetrical cylinder and the corresponding volume are shown as follows: (22) where, is the effective area of asymmetrical cylinder rodless cavity, is the effective area of asymmetrical cylinder rod cavity, is the piston position of asymmetrical cylinder, is the internal leakage coefficient of asymmetrical cylinder, is the elastic modulus of effective volume, is the initial volume of asymmetrical cylinder rodless cavity, is the initial volume of asymmetrical cylinder rod cavity.…”

Section: ) Flow Continuity Equationmentioning

confidence: 99%

Design, Mathematical Modeling and Force Control for Electro-Hydraulic Servo System With Pump-Valve Compound Drive

Zhu

Yao

et al. 2020

IEEE Access

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Each joint of hydraulic drive legged robot adopts highly integrated electro-hydraulic servo system, and the system has two common forms, namely, valve-controlled cylinder system and pump-controlled cylinder system. The former has a large energy loss, which restricts the endurance of the legged robot in the field. Although the latter has the advantages of energy saving and high efficiency, the overall response ability of control system is unsatisfied. In this paper, a novel pump-valve compound drive system (PCDS) is designed. It combines the advantages of pump-controlled cylinder system and valve-controlled cylinder system, which can not only effectively reduce the energy loss of the system, but also ensure the electro-hydraulic servo system of the robot joint has the ideal response ability. This paper consists of three parts. In the first part, the mathematical model of nonlinear force control of PCDS is established, which takes into account the pressure-flow nonlinearity of servo valve, the asymmetry of servo cylinder and the complexity and variability of load. So this model has a high accuracy. In the second part, On the basis of the above model, a force control method combining tracking error compensation and load compensation control is designed. And this control method can improve the control accuracy of the robot. In the third part, the performance of the designed control method is verified by experiments. The experiments show that the designed force control method can effectively reduce the influence of external position disturbance on the tracking accuracy of the force control system and improve the control accuracy of the robot joint movement.

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“…Valve control systems respond quickly to valve and load inputs but are less efficient due to throttling and overflow losses [2,3]. Pump control systems work efficiently since both system pressure and flow are closely matched with load requirements [4,5] but have a critical drawback: slow response. The variable speed pump control (VSPC) system is a new class of pump control system, using a variable speed motor to drive a fixed displacement pump, which is applicable to hydraulic elevators [6], shield tunneling machine [7] and water distribution systems [8,9].…”

Section: Introductionmentioning

confidence: 99%

The Influence of Valve-Pump Weight Ratios on the Dynamic Response of Leaking Valve-Pump Parallel Control Hydraulic Systems

et al. 2018

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A new leaking valve-pump parallel control (LVPC) oil hydraulic system is proposed to improve the performance of dynamic response of present variable speed pump control (VSPC) system, which is an oil hydraulic control system with saving energy. In the LVPC, a control valve is operating at leaking status, together with a variable speed pump, to regulate the system flow of hydraulic oil simultaneously. Therefore, the degree of valve control and pump control can be adjusted by regulating the valve-pump weight ratio. The LVPC system design, mathematical model development, system parameter and control performance analysis are carried out systematically followed by an experimental for validation process. Results have shown that after introducing the valve control, the total leakage coefficient increases significantly over a wide range with the operating point and this further increases damping ratios and reduces the velocity stiffness. As the valve-pump weight ratio determines the flow distribution between the valve and the pump and the weight factors of the valve and/or the pump controls determines the response speed of the LVPC system, thus if the weight factors are constrained properly, the LVPC system will eventually have a large synthetic open-loop gain and it will respond faster than the VSPC system. The LVPC will enrich the control schemes of oil hydraulic system and has potential value in application requiring of fast response.

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Independent volume-in and volume-out control of an open circuit pump-controlled asymmetric cylinder system

Cited by 14 publications

References 18 publications

Classification and Review of Pump-Controlled Differential Cylinder Drives

Classification and Review of Pump-Controlled Differential Cylinder Drives

Design, Mathematical Modeling and Force Control for Electro-Hydraulic Servo System With Pump-Valve Compound Drive

The Influence of Valve-Pump Weight Ratios on the Dynamic Response of Leaking Valve-Pump Parallel Control Hydraulic Systems

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