Method for combining valves with symmetric and asymmetric cylinders for hydraulic systems

ABSTRACT

Electro-hydraulic position control systems are widely applied in several fields. The valve and cylinder configuration and the dimensioning of these systems is dependent on the requested transient response and the load profile. One of the primary factors in this regards is the selection of an asymmetric or symmetric cylinder, considering issues such as the area available for installation and the asymmetry of the external loading. According to the classical literature, the valve control orifice areas must be matched with the cylinder areas to ensure balanced pressure variation in the cylinder chambers. Moreover, considering that several real applications use non-matched components, it is evident that, depending on the system parameters and load characteristics, good performance can be obtained with this system configuration. Based on non-linear dynamic modelling and experimental results, the transient instants when cavitation or high pressure peaks can occur are determined. Subsequently, a set of equations establishing the relationship between the valve control orifice ratio and cylinder area ratio are derived. A method for determining the valve characteristics, based on parameters such as moved mass, external load force and cylinder asymmetry, is presented. The results obtained are also valid for speed control in open or closed loop system.

KEYWORDS:

• Electro-hydraulic system
• hydraulic circuit design
• component sizing
• asymmetric and symmetric cylinder
• proportional valve

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the CNPq (the Brazilian National Council for Scientific and Technological Development)

Notes on contributors

Mário C. Destro

Mário C. Destro received his Master in Mechanical Engineering in the field of Mechanical Design Systems with emphasis on Hydraulic and Pneumatic Systems, at Federal University of Santa Catarina (UFSC). At the moment, he is PHD student in the field of hydraulic systems at the POLO–Research Laboratories for Emerging Technologies in Cooling and Thermophysics at UFSC.

Victor J. De Negri

Victor J. de Negri has been Head of the Laboratory of Hydraulic and Pneumatic Systems (LASHIP) at the Department of Mechanical Engineering, Federal University of Santa Catarina (UFSC), Brazil, since 1995. He received his D. Eng. degree in 1996 from UFSC. He is a member of ASME and ABCM and Associate Editor of the IJFP and JBSMSE. His research areas include the analysis and design of hydraulic and pneumatic systems and design methodology for mechatronic systems.