Fluid Power Laboratory, Institute of Machine Design, Cracow University of Technology, Poland 

Location Krakow, Poland
Contact Person Dr. Andrzej Sobczyk
Laboratory facilities about 300 m²
Address Al. Jana Pawla II 37
31-864 Krakow, Poland
Telephone number +48 12 628 3405
Fax number +48 12 628 3360
Email sobczyk@mech.pk.edu.pl
Internet Site http://graf.mech.pk.edu.pl

From Editor

International Journal of Fluid Power would like to introduce the fluid power research and education centres with their expertise and particular interests in this column. Jumping from continent to continent we like to offer every research centre the opportunity to present itself.


FLUID POWER RESEARCH CENTRES WORLD-WIDE

General Information

The idea to found Cracow University of Technology (CUT) was initiated at the end of 2nd World War as a consequence of political decisions. At the end of 1945 Rector of the Academy of Mining in Krakow obtained a formal agreement to incorporate the new school and create Polytechnic Departments: Architecture, Surveying Engineering, Civil and Water Engineering and Forestry Department. The document authorising the legal activity of Departments was signed on October 6, 1946 - this date is identified as the date of foundation of CUT. As fully independent university CUT has been acting since 1954. The main premises of CUT are located on Warszawska St. since 1948. As a result of the partly executed plan of school's extension in Czyzyny (a district in Krakow), modern buildings of Faculty of Mechanical Engineering with laboratory facilities and four large halls of residence for students have been added.
In 1976 the 30th Anniversary of CUT was celebrated, and on this occasion the school was given the name of Tadeusz Kosciuszko - the great Polish and American leader-hero, politician, organizer and engineer.
During 50 years of activity, the CUT has became a leading university, with over 37000 graduated students, more than 2100 employees, including over 1200 academic teachers, and more than 70 professors. The CUT is one of the three universities in Krakow that fulfil all requirements of an independent university. The CUT ranks in the top 10 Polish technical universities in all fields. Some of its faculties including Architecture, Civil Engineering or Mechanical Engineering are elite.
During the 2002/2003 academic year, the CUT had more than 17000 B.Sc. and M.Sc. students in 16 fields. CUT is also teaching students outside of Krakow, for example: Tarnów, Nowy Sacz, Zywiec, Chrzanów. There are about 250 Ph.D. students. The Faculty of Mechanical Engineering (Fig. 1) is teaching students in the following fields:


Fig. 1: Faculty of mechanical engineering

Fluid Power Laboratory

Fluid Power Laboratory is a part of Institute of Machine Design. Workers in the laboratory are:


Fig. 2: Variable efficiency pump test stand

The Fluid Power Laboratory carries out research and development activities as well as teaching activities. The laboratory is equipped with specialized test stands designed to determine characteristics or test elements and circuits. For example test stands for determining the characteristics of: variable displacement pumps (Fig. 2), pressure relief valves, hydro-static transmission, hydro-kinetic clutch, determining the parameters of control in hydraulic control system of the wheel steering mechanism (Fig. 3), and to determine the work characteristics and efficiency of a hydraulic cylinder.




Fig. 3: Hydraulic wheel steering test stand

Beside the projects, thanks to an agreement on collaboration with CATERPILLAR, the laboratory was equipped with a mini-excavator (Fig. 4a,b), with hydraulic drive. This allows studying the work characteristics of drive and control of boom, arm, bucket, swing and drive mechanisms, – in theory and under true working conditions.




Fig. 4a: Field tests of a CAT 301.05 mini-excavator and sample mechanism work parameters

The Laboratory is extensively involved in activity of Fluid Power Net, an international network focused on fluid power and fluid power related topics, coordinating its activities in Poland.
The most of the laboratory facilities is used in education process for about 120 3rd year M.Sc. students and 20 of 4th year students for laboratory exercises as well as for M.Sc. or Ph.D. projects.




Fig. 4b: Field tests of a CAT 301.05 mini-excavator and sample mechanism work parameters

Projects carried out by the laboratory


Main areas of research

Computer simulation and modelling of hydraulic and pneumatic circuits as well as elements of machine drive and control circuits (Fig. 5), including their experimental verification.
Characteristics shaping and selection of drive and control circuits for construction machines, including construction manipulators, analysis of hydraulic-combustion, -electric, and other types of drives.
Control and automation of machines, use of robots and manipulators in civil engineering, including road and bridge construction.

Fig. 5: Simulation model of hydraulic swing mechanism



Fig. 6: Hydraulic drive and control circuits with ecological oil test stand

Design and construction of energy saving drive and control circuits with energy recovery systems, in frame of the second CATERPILLAR project.
Studies on application of hydraulic drive and control circuits with ecological working mediums such as biodegradable oils carried out on a specially designed test stand (Fig. 6), built for the CATERPILLAR project.
Research and development studies on the use of water as a working medium in drive and control circuits of machines are conducted on a specially constructed test stand (Fig. 7) equipped with mechatronic drive and control circuit (we called it ‘hydrotronic’) with the ability of control through the internet. The stand was built with funds form National Science Committee (KBN) and thanks to support of water hydraulic elements manufacturer - DANFOSS from Denmark.





Fig. 7: Water hydraulics test stand

Pneumatic Circuits with PLC Controllers

As a part of development of a pneumatic circuit a modern industry automation circuit was used. This could be done by using programmable PLC controllers. The circuit is used for representing work of a PLC controlled pneumatic circuit and for students to allow them programming of PLC controllers. The simulation experiments are focused on the possibility of such control and the phenomena in pneumatics under different conditions and loads. Currently the circuit is being rebuilt to allow the possibility of wire control of the circuit based on connection with the control circuit through the internet (Fig. 8).
To achieve the research and development projects the laboratory is equipped with sophisticated laboratory equipment for measurement and transfer (including wireless) of test data and digital acquisition and analysis of the measured signals. For example signal of such quantities as: pressure, flow intensity, temperature, linear and angular displacement, linear and angular velocity, acceleration force, torque, stress, strain etc.




Fig. 8: PLC controlled pneumatic manipulators

Low Temperature Experiments

One of the very important aspects of the research carried out by the Fluid Power Laboratory are low temperature experiments. Thanks to a range of different size climatic chambers, owned by the laboratory, and sophisticated collecting and analysis of data, it is possible to study a wide variety of machine parts and machines in a low and high temperatures (Fig. 9).




Fig. 9: Military vehicle during tests in the climatic chamber




Fig. 10: Dimensions of the large climatic chamber


Testing Properties of LS Circuits

The laboratory is also studying the characteristics of Load-sensing circuits (Fig. 14), with a variable efficiency pump type HLP 57 manufactured by Danfoss and with a distribution valve type PVG 32 equipped with PVES sections – high precision control and no hysteresis. The studies include determination of static characteristics and phase-amplitude characteristics for different types of loads.
As a part of research on saving energy in machines, simulation and laboratory experiments (Fig. 12) are carried out to determine the properties of hydro-pneumatic bladder and piston accumulators which are used as a secondary power source in circuits equipped with energy recovery systems. The simulation experiments are focused on the heat exchange process in different thermal conditions and its influence on accumulator efficiency (Fig. 13).



Fig. 11: Multi-purpose Load-sensing system test stand

Investigation of Hydro-Pneumatic Accumulator Properties




Fig. 12: Hydro-pneumatic accumulator test stand
Fig. 13: Graphical representation of heat exchange for bladder accumulator and an example of experimental and simulation results for accumulator work cycle



Fig. 14: Hydraulic schema of Load-sensing system test stand


 

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