A Case Study of Open- and Closed-Loop Control of Hydrostatic Transmission with Proportional Valve Start-Up Process

Abstract

This paper concerns the start-up process of a hydrostatic transmission with a fixed displacement pump, with particular emphasis on dynamic surplus pressure. A numerically controlled transmission using a proportional directional valve was analysed by simulation and experimental verification. The transmission is controlled by the throttle method, and the variable resistance is the throttling gap of the proportional spool valve. A mathematical description of the gear start-up process was obtained using a lumped-parameters model based on ordinary differential equations. The proportional spool valve was described using a modified model, which significantly improved the performance of the model in the closed-loop control process. After assuming the initial conditions and parameterization of the equation coefficients, a simulation of the transition start-up was performed in the MATLAB–Simulink environment. Simulations and experimental studies were carried out for control signals of various shapes and for various feedback from the hydraulic system. The pressure at the pump discharge port and the inlet port of the hydraulic motor, as well as the rotational speed of the hydraulic motor, were analysed in detail as functions of time. In the experimental verification, complete measuring lines for pressure, speed of the hydraulic motor, flow rate, and temperature of the working liquid were used.

Numerical Heat Transfer and Fluid Flow: A Review of Contributions to the Special Issue

“…For example, in the system with fixed displacement pumps controlled by the throttle method, the main approach is to limit the operation of the safety valve. Bury et al [35] performed simulations and experiments with control signals of various shapes and feedback from the hydraulic system. The authors analyzed the pressure at the pump inlet and outlet, the flow rate, and the rotational speed of the hydraulic motor as functions of time.…”

“…On the basis of the analyses, the authors concluded that the maximum pressure value at the inlet port of the hydraulic motor during its start-up can be modified by adjusting the shape of the proportional spool valve (symmetrical, asymmetrical). This solution also reduces the noise caused by the transmission during start-up and reduces the load on elements of the transmission, which extends its operational life [35].…”

Load sensitive control characteristics of a novel two-dimensional pulse width modulated variable mechanism

“…Moreover, the system can also control the quantitative pump through the hydraulic valve to achieve load sensitive functions, such as proportional valves, digital valves, etc. Bury et al 26 proposed the combination of proportional solenoid valve and quantitative pump, through the proportional solenoid valve to distribute flow to the quantitative pump, to achieve load sensitive function. However, the combination of proportional valve and quantitative pump can cause significant overflow loss and relatively low efficiency.…”

Coincidence of pressure pulsations with excitation of mechanical vibrations of hydraulic system components: An experimental study

“…Due to the above, a significant impact of external signals on the operation of modern proportional elements or hydraulic microvalves is to be expected, as interferential excitation forces in these components may be of the same size as the controlling forces, leading to many detrimental effects that include stability loss, lack of positional precision, sealing damage, and increased noise generation (Kollek et al, 2010). At present, there is a strong tendency for proportional control technologies to be developed in various types of hydraulic components (Jesionek et al, 2004b;Tomasiak, 2001), replacing the previously used conventional components and opening up new possibilities with regard to time of response to control signals (Cichoń and Stosiak, 2011) and bandwidth frequency, and completely new opportunities for performing pre-programmed work cycles, reducing dynamic surplus and mitigating transitional states (Kudźma and Stosiak, 2013;Bury et al, 2022). Modern medical devices and industrial robots are equipped with proportional components such as proportional directional valves, proportional overflow valves, electrohydraulic boosters, and increasingly commonly, hydraulic microvalves (Jesionek et al, 2004a;Kollek (ed.…”