Jarosław Kałużny

Piston assembly in the most powerful 2.0l diesel engine – case study of the current tribological system and innovative concepts for the future

This article is a contribution to the ongoing debate on the scenario of the vehicle powertrains development. The directions of the internal combustion engines development in search of the possibility of effective economic and ecological indicators improvement have been indicated. It has been pointed out that this goal can be achieved through the use of nanotechnology in order to exceed the downsizing barriers resulting from the permissible mechanical loads for conventional materials. The article presents the study of the construction and materials used in the piston assembly of the most advanced four-cylinder, compression-ignition diesel engine currently in manufacture. Original concepts of nanotechnology have been proposed to reduce friction losses in major friction components of future engines with extremely high loads. The main idea is to verify the hypothesis that the sub-micron surface texture of the friction components obtained in the process of applying anti-wear outer layers can lead to an effective reduction of friction losses under real engine operating conditions. Computer simulations of the effects of introducing the surface texture in the upper sealing ring on friction loss confirm this hypothesis by showing friction value being reduced by 3-4% relative to the standard ring profile. In the summary, further advanced technologies designed to effectively utilize the unique properties of carbon nanotubes have been described.

The Numerical Analysis of Influence of Crankshaft Main Spindles Regeneration in Marine Engine on Stiffness and Eigenfrequency of the Crankshaft

Engine operating conditions of the main propulsion, static in principle with steady-state rotation speed of the crankshaft and engine load, also work under dynamic load conditions. These conditions cause additional distortion of the crankshaft and changes in the operating conditions of the shaft bearings. However, the greatest impact on the long and trouble-free operation has proper engine maintenance. Variable operating conditions and engine operating errors, unfortunately, often cause damage to the main bearings of the crankshaft. Repair of the damaged main bearing spindles of the shaft involves performing the machining of the spindle surface then its re-hardening and selecting new bearing bushings with the appropriate bearing clearance. Trusting the engine manufacturer, there is no check of the influence of the machining of bearing spindles on the structural properties of the shaft. Therefore, the paper presents the model tests of the structure of medium-rev marine engine crankshaft aimed at determining the changes in the mechanical properties of the structure resulting from carrying out the regeneration of the main shaft spindles.

Comparing the resistance to motion of pistons coated with a layer of nanotubes with standard pistons

The paper presents preliminary results of testing the resistance to motion of pistons coated with a layer of carbon nanotubes (CNTs). A significant part of this paper was devoted to the problems of putting a layer of nanotubes on the surface of an aluminum alloy. Obtaining a layer of nanotubes of a very narrow margin of tolerance was a difficult technological problem to overcome. A standard process of growing a layer of nanotubes leads to a corrosion damage of the side surface of pistons; therefore, new technologies were developed allowing for obtaining a permanent layer of nanotubes less than 5 microns thick. Pistons whose side surfaces were coated with a layer of nanotubes were mounted to an engine with an external drive, and then measurements of the moment of momentary resistance to motion were performed, which enables capturing these phases of the engine work cycles in which the layer of nanotubes gives the best results. At present, long-term research is being carried out in order to determine the degree of the risk of exfoliation of the layer of nanotubes under the conditions of large mechanical and thermal loads. The special nanotechnology method cold nanosphere lithography has been invested to control the structural properties sand growth of multiwalled carbon nanotubes. The preliminary analysis of dismantled pistons revealed that nanotubes layers were partially worn off at the peaks of micro roughness but in the valleys, the nanotubes accurately adhered to the piston lateral surface.