Dominik Rabsztyn

Influence of the Controller Settings on the Behaviour of the Hydraulic Servo Drive

The article presents the influence of the position loop gain setting on the position error values of the hydraulic servo drive. Results of the experimental tests have also been compared with the analytically determined gain values. For the tests, servo cylinder has been loaded with the active force of 2500 N, pointed in the direction opposite to the direction of piston rod extension. The result of the experimental tests was the discovery that the accuracy and stability of the servo drive positioning depends not only on the value of Kv factor, but is also influenced by the direction of the active force loading the servo cylinder. In the tested hydraulic servo drive (hydraulic axis controller), the Compax3F controller by Parker Hannifin was used.

Experimental analysis of hydraulic discharge line in the frequency domain

The article presents the results of the experimental test of the pressure pulsation propagation across hydraulic line. The tests have been conducted in the form of a complete two-level experiment, having selected the following parameter variables: flexible hose type (1 or 2-wire hose), pressure value in the pressure line, rotational speed of the pump shaft, pressure line length. The series of pressure runs were analysed in frequency domain using FFT method. The results confirmed the prediction that the discharge line should be treated as a hydraulic transmission line (similar to the long transmission line) with distributed parameters, which variously attenuates pressure pulses of different frequencies.

Experimental analysis of hydraulic discharge line in the time domain

The article presents the results of preliminary experimental analyses of damping pressure pulsation by the hydraulic flexible hoses. The tests have been conducted in the form of a complete two-level experiment, having selected the following parameter variables: flexible hose type (1 or 2-wire hose), pressure value in the pressure line, rotational speed of the pump shaft, pressure line length. The acquired curves have been analysed in time domains. Values of pressure line damping in relation to the dominant pressure peaks have also been determined. The aim of the undertaken tests has been to confirm or overthrow the common belief that the pressure line with flexible hose itself is the sufficient damper of pressure pulsation in a hydraulic pump.

Verification of the Theory of Construction Similarities in the Connectors

Theory of construction similarity allows creating ordered construction families (series of types, modular construction systems). On the basis of the specific conditions of construction similarity and values of model characteristics, the parameter and dimension values have been determined. For the purpose of practical verification of the conditions of construction similarity the strength verification with MES and practical verification with a ripper have been performed. An attempt at practical verification of the construction similarity has been also performed using the ripper. The tests have been carried out with the use of threaded and welded joints and grippers. For that purpose, on the basis of conditions of construction similarity and dimensions of model construction, the construction series of types has been created.

Experimental Tests of Pressure Pulsation of Gear Pumps

The paper presents results of experimental tests regarding pressure pulsation of the gear pump with external gear design. A cycle of measurements was carried out in relation to the selected parameters of system’s operation such as temperature of hydraulic fluid (viscosity) and pressure of the pressure line. The obtained results of pulsation measurements were analyzed in terms of time and frequency. The time analysis was carried out in order to determine the peak-to-peak value of pumping pressure that is responsible for generating increased levels of vibration and noise, as well as influences fatigue wear of the hydraulic system elements. The frequency analysis was carried out in order to identify the pressure values not related to periodical changes in pump capacity, which may be used to diagnose the operation condition of the pump. Research has shown that increase of pumping pressure and temperature of the oil causes significant increase of the pressure pulsation amplitude resulting from the eccentricity of gearwheels.

Preliminary CFD Analysis of the Influence of the Geometry of the Selected Element on the Fluid Flow in the Tank of the Hydraulic System

The article analyses the influence of the geometry of the downflow and suction lines and perforated baffle on the even flow of the working fluid in the tank of the hydraulic system. During the tests, more attention was paid to identifying the influence of the shape of wires on the phenomena connected with the flow of the fluid in the tank. We considered typical, and recommended by producers of the elements and hydraulic systems, construction forms of pipes introduced vertically into the tank, and comparing them to the pipes cut at a right angle. Since for simulation testing only one construction form was adopted, in this respect the results are only basic. Analyzing the results of simulation, it has been observed that the evenly perforated baffle does not bear significant influence on the equal distribution of fluid flow in the tank.

The Process of Parameterization and Creating Reference Construction

In the process of creating a series of types of construction, it is important to develop a reference construction that best meets the principles of construction and right of existence of technical product [1, 2, 3]. Construction of reference in the family construction can be selected from among existing structures or designed from the ground up as shown this publication. This is a construction practically verified in terms of its function (CAD simulation) and subject to optimization (particularly CAE strength optimization) that was verified due to the production (technology was developed in CAM) and the obtained product was subject to experimental verification (prototype tests).