Traditionally, a typical hydraulic circuit utilized in stationary industrial applications is based on valve operated actuation. One realization of such a system is a constant pressure circuit employing a hydraulic accumulator as an energy reserve and pressure stabilizer. The pump is used to maintain the desired pressure level, for example by using a variable displacement pump that controls the displacement setting based on the pressure level.
The main benefit of this system architecture is its ability to produce high output powers with a very low response time. However, it is not the most energy efficient and in many cases, not the most space efficient solution. The efficiency of this system type is reduced mainly by the need to choke the pressure difference between the set system pressure and the actual pressure need in the actuator. By directly controlling the actuator via controlling the pump’s output flow with an electric servo motor, the throttling losses of the valve controlled system can be avoided. In addition, this enables the usage of closed circuits which in terms removes the need for a large reservoir.
In this study, the replacement of a valve controlled hydraulic system with a pump controlled system in an industrial stationary material handling machine is investigated. The machine’s work cycle consist of continuous consecutive lifting and lowering motions of one end of a platform pivoted at the opposite end. The study consist of designing the replacing circuit topology, of dimensioning the hydraulic components utilizing a created Simulink-based tool and of a simulation based analysis on the dynamic properties of the designed hydraulic system.