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Analysis of screw connection in air conditioning systems

Jírová Radka, Pešík Lubomír

Zeszyty Naukowe. Transport / Politechnika Śląska

2022

z. 114

43--54

Air conditioning systems in vehicles require long-term reliability during their entire service life. Especially, a good sealing function is needed for the prevention of coolant leaking. Unfortunately, in specific cases, after a particular time, screw connections of the air conditioning circuit lose their tightness, and the coolant starts to leak. Therefore, this paper focuses on the analysis and design optimisation of screw connections. We used the finite element method for describing the sealing, screw and disc spring behaviour. Then, we proposed a new design of the disc spring to obtain the proper force-deformation characteristics of the connection and ensure the tightness of the screw connection.

The impact of the energy state of the surface of friction pairs on the friction and wear in internal combustion engines

Borkowska J., Kaźmierczak A., Krakowian K., Cienciała M., Skorupa P., Łoza Ł.

Journal of KONES

2015

Vol. 22, No. 4

37--41

The elements creating a friction pairs are described to be very difficult in terms of defining all optimal parameters in an unequivocal way. The research on stability of friction pairs is focused on the surface and the top layer of surface in the parts concerned. The main goal is to find new design solutions and materials, thereby achieving one million kilometers of mileage to main repair in the case of internal combustion engines. The biggest structural difficulties are noticeable in friction pairs where it can be observed sliding and returning motion, which is also connected with sealing function. A typical example of such pair is piston ring – cylinder sleeve in piston – rings - cylinder unit in an internal combustion engine. Engineers are currently seeking an additional factor, which would enable gaining the reduction of tangential force by reducing the friction coefficient in elements of friction pair during operations. The surface free energy may be such factor - it results from molecular structure and nature of the bonds between the molecules present in the material. Components of surface free energy determine the tribological properties of the material, which is reflected in the stability of the units. Energy state of the surface, which is connected with chemistry and characteristics in the material, is the first step to consider about the impact on wearing in internal combustion engine. This is the main topic of this article.