W. Kollek

The Influence of Gear Micropump Body Asymmetry On Stress Distribution

Abstract The paper presents the results of numerical calculations of stress distributions in the gear micropump body for applications in hydraulic systems, especially in the marine sector. The scope of the study was to determine the most favorable position of bushings and pumping unit in the gear pump body in terms of stress and displacement distribution in the pump housing. Fourteen cases of gear pump bushings and pumping unit locations were analyzed: starting from the symmetrical position relative to the central axis of the pump, up to a position shifted by 2.6 mm towards the suction channel of the pump. The analysis of the obtained calculation results has shown that the most favorable conditions for pump operation are met when the bushings are shifted by 2.2 mm towards the suction channel. In this case the maximal stress was equal to 109 MPa, while the highest displacement was about 15μm. Strength and stiffness criteria in the modernized pump body were satisfied.

Possibilities of diagnosing cavitation in hydraulic systems

Conditions of arising cavitation and experimental investigations of this phenomenon by means of a special vacuum vessel are described. A simulation model of the piston–cylinder unit of a pump with an inclinable cylinder block was used to visualize cavitation in the pump. The results of tests aimed at showing a correlation between the onset of cavitation and an audible diagnostic signal are presented. The suction space of the tested axial-flow multipiston positive-displacement pump with an inclinable cam plate was selected as the most likely place for cavitation to occur. An audible diagnostic signal indicating the onset of cavitation was also detected in the case of a multipiston pump with an inclinable cylinder block. An example of the configuration of an acoustic probe kit for use under industrial conditions is presented.

Performances of high-speed pneumatic drive with self-acting impulse valve

Results of a simulation and experimental research on a high-speed cylinder with self-acting impulse valve are presented. Dynamics of the cylinder was described using the mathematical model formulated by E.W. Gerc. It was shown that differences between maximum speeds developed by the cylinder, determined in the simulation and experimental research, do not exceed 5%. The obtained results prove correct analytical description of dynamics and performance of the high-speed cylinder. The accepted mathematical model can make a basis for selection of design parameters and working conditions of a high-speed cylinder with self-acting impulse valve.

The didactic and scientific research capabilities of the Laboratory of Hydraulic Drives & Vibroacoustics of Machines

The didactic and scientific research capabilities of the Laboratory of Hydraulic Drives & Vibroacoustics of Machines