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The Fourier transform as a new approach of evaluating the internal combustion engine indicator diagram

Łoza Ł., Sitnik L. J.

Journal of KONES

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2017

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Vol. 24, No. 4

173--180

EN

In this paper, the authors present an introduction to the new method of evaluating the indicator diagram of internal combustion engine. For several years, it was observed that analyses of combustion processes have been hardly changed since they were conducted for the first time. At the moment, the diagrams are plotted more and more precisely owing to the new sensors and digital processors. Despite all of these high technical advantages, which were obviously unavailable in the past, theoretical approach for describing indicator diagram has not changed in significant way. Nowadays, the indicator diagrams are still evaluated very generally and are presented in much too idealistic way as a smooth curve of pressure changes, without any disturbances, which are being detected very easily now. Furthermore, it appears that performance improvements of the IC engines are in need of developing new methods for analysis and evaluation. The Fourier transform is a new way to look at the combustion process in the engines. It is basically a mathematical instrument for analysing different types of signals, which are transformed, from time domain into frequency domain. It enables identifying specific sinusoidal components of arbitrary signals and separates relevant ones from the noise. This allows one to see significant differences in two or more apparently similar signals and detect the crucial parts. If we treat pressure changes in time like a common signal, we can compute Fourier transform and see basic components of the diagram.

2

Various designs of the two-stroke engine heads with the valve flushed system

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

Journal of KONES

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2015

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Vol. 22, No. 4

187--190

EN

The two-stroke engines have never acquired the popularity of the four-stroke engines due to their inherent performance limitations. The tasks of many engineering teams were to find the basic causes, which resulted in the inferior performance of these engines. Today’s task is to build a two-stroke engine whose performance could match that of a four-stroke engine in areas of common use. The most typical performance problems of a two-stroke engine are high petrol consumption caused by low efficiency, toxic by-products of combustion being emitted into the atmosphere (caused by oil present in the petrol), and uneven and loud engine noise. The greatest challenge is to achieve a good chamber purge during one stroke in which the fresh fuel mixture flows through the piston-controlled inlet port while at the same time the fumes are being exhausted through the outlet port. This in contrast with the four-stroke engines where the intake and exhaust are each done with two separate strokes. From the energy point of view, the two-stroke engine is not efficient because a certain amount of fresh fuel is being wasted in the exhaust fumes. We propose to replace the piston-controlled cam with the valve-flushed system, which will cause the combustion process to become more efficient. The purpose of this paper is to present various designs of the engine heads and analyse their performance. The goal of this proposal is to choose the best combination of these engine heads in order to achieve the optimum overall engine performance.

3

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

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2015

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Vol. 22, No. 4

37--41

EN

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.

4

Review of possibilities of increasing the thickness of an anti-wear coating on piston rings by using specifically designed physical vapour deposition process

Skorupa P., Kaźmierczak A., Błasiński T., Borkowska J., Krakowian K., Łoza Ł.

Journal of KONES

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2015

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Vol. 22, No. 4

281--286

EN

The super-hard, anti-wear amorphic coatings based on carbon-like diamond (called DLC) show a promising direction in automotive industry, mainly in terms of decreasing friction coefficient in parts of internal combustion engine. However, the technology of producing DLC-coated parts, which is most often chemical vapour deposition (CVD) or physical vapour deposition (PVD) is proven to be still not perfect for achieving desired characteristics of the coating. The thickness of a coating is the main issue one should strive to improve, as the PVD methods produce films as thin as few micrometres. In such case, the coating is not only exposed to cracking, but also pitting is possible to happen. This is proven to be highly undesirable and unacceptable for this process. In addition, in case of thin films, the adhesion to the base is often too weak, despite the coating itself being extremely durable and hard. In this article, a theoretical ways to improve the process of coating are presented. The process itself is described, the achievable parameters are defined and the possible improvements are stated. The research made for the purpose of this article will be further exploited to design a process allowing creating the coating for testing of the best possible characteristics.