Grzegorz Koszalka

Chosen Aspects of Municipal Transport Operation on the Example of the City of Lublin

Abstract The paper presents some aspects of operation of municipal transport system in the city of Lublin (Poland). Organization of Lublin Municipal Transport Company was described, its efficiency and perspectives of development. Particular attention was paid to the rules of adjustment to the EU requirements, and to the influence of demographic and social factors. Infrastructure of public transport in Lublin was analyzed (busses, trolley‐busses, bus stations, fixed objects and bus stops), as well as configuration of bus and trolley‐bus lines. Some specific proposals were also put forward regarding development solutions: development plan of trolley‐bus traction, plan of inter‐connection bus station, development plan of bus traction, introduction of advanced IT solutions into the public transport management and natural gas (CNG) fuelling of the city busses. Keywords: urban transport, urban transport problems.

Mathematical Model of Piston Ring Sealing in Combustion Engine

Abstract This paper presents a mathematical model of piston-rings-cylinder sealing (TPC) of a combustion engine. The developed model is an itegrated model of gas flow through gaps in TPC unit, displacements and twisting motions of piston rings in ring grooves as well as generation of oil film between ring face surfaces and cylinder liner. Thermal deformations and wear of TPC unit elements as well as heat exchange between flowing gas and surrounding walls, were taken into account in the model. The paper contains descriptions of: assumptions used for developing the model, the model itself, its numerical solution as well as its computer application for carrying out simulation tests.

Reliability assessment of a truck engine based on measurements of combustion chamber tightness

The article shows an analysis of the reliability of a compression-ignition engine used in a medium duty truck. The criterion for the reliability assessment was the decrease in combustion chamber tightness. The analysis was based on the results of compression pressure tests and leak-down tests conducted during a long-term operation of 5 trucks. Experimental survival functions and then continuous reliability functions, fitted to the empirical ones, were determined along with the failure rate functions.

A simulation study on the manoeuvrability of a large size semitrailer

AbstractAs part of a research project aimed at designing the structure of a new special-purpose multi-axle semitrailer for transporting large machines and equipment, a simulation study on the manoeuvrability of the semitrailer during its passage through a tight corner was performed. The aim of this study was to determine whether the semitrailer would meet the legal requirements regarding manoeuvrability after it has been implemented for production. The simulations were carried out using a specially designed spreadsheet. The spreadsheet enabled analysis of the movements of the wheels of the tractor-trailer combination, with the assumption that they roll without skidding; it also described changes in the steering angles of trailer wheels, as well as off-tracking and corner-cutting during turning. When the geometrical parameters of the tractor and trailer were changed, the spreadsheet allowed tracing their impact on the manoeuvrability of the whole combination. This paper presents the results of the simulati...

A numerical model for calculation of piston rings wetted area in a combustion engine

Assumptions made while modelling the oil film between the ring and the cylinder liner in IC engines, especially concerning the boundaries of the wetted area of the ring face surface, were discussed and the assumptions adopted for the developed model were presented in this study. It was assumed that the model should take into account partially flooded lubrication, which meant that the boundaries of the ring wetted area had to be determined. Based on the adopted assumptions, a model for calculation of the oil film thickness between the cylinder and moving rings, and thickness of the oil film left on the cylinder by the ring pack was developed. A computer application operating in the Windows operation system was developed to carry out numerical calculations. The results of initial numerical calculations were also presented. The proposed model can be utilized to determine the effects of the ring pack geometry, especially the geometry of the ring surface, on parameters of lubrication. These parameters, including the oil film thickness, distribution of pressure in oil film or tangential force, are crucial for friction and wear of cooperating surfaces, oil consumption, and flow of gas from the combustion chamber to the crankcase, thus playing a role in the durability, fuel consumption and emission of an engine.

Prediction of IC Engine Power System Durability with the Use of Ring Pack Model

Prediction of IC Engine Power System Durability with the Use of Ring Pack Model The paper presents the new method of engine life prediction, which bases on the results of wear measurements taken on an investigated engine and simulations carried out with the use of the analytical model of ring pack of the engine. In the contrary to traditional methods the proposed method does not require the prior knowledge of the limit wear value, which is essential for the prediction, however its reliable establishing for new engines is difficult. In the presented method its value is determined with the use of the ring pack model. The example of durability calculation for an automotive diesel engine is also presented. Przewidywanie trwałości układu tłok-pierścienie-cylinder silnika spalinowego z wykorzystaniem modelu uszczelnienia TPC W artykule przedstawiono nową metodę prognozowania trwałości silnika, wykorzystującą wyniki pomiarów zużycia elementów układu tłokpierścienie-cylinder oraz wyniki badań symulacyjnych modelu uszczelnienia TPC silnika. W przeciwieństwie do tradycyjnych metod, proponowana metoda nie wymaga wyprzedzającej znajomości zużycia granicznego, która jest kluczowa dla dokładności prognozy, a której wiarygodne określenie dla nowych konstrukcji jest trudne. W prezentowanej metodzie wartość zużycia granicznego wyznaczana jest z wykorzystaniem modelu uszczelnienia TPC. W artykule przedstawiono przykład wykorzystania metody do prognozowania trwałości samochodowego silnika o zapłonie samoczynnym.