Łukasz Zieliński

Using Vibroacoustic Signals in Evaluation of Knocking Combustion in a Dual Fuel Engine

Current development of automotive domain heading towards the ever decreasing pollution emission as well as using the alternative fuels resulted in analysis of the possibilities to power the combustion engines with combinations of several fuels. The multi-fuel engines designed in such a way can use the advantages of specific fuel. The most popular trend uses self-ignition engines to operate on the fluid fuels such as the diesel oil or its mixtures, and on the gaseous fuel such as CNG or LPG. In Poland, because of the extensive network of LPG stations, the interest in adapting vehicles to this type of fuelling increases. This is particularly vital for heavy and large goods vehicles, in the case of which the fuel saving possibility of a few to a dozen or so percent is very interesting. Using gaseous fuels in engines with the self-ignition results in the occurrence of the previously unknown phenomena. Such a phenomenon is, among others, the knocking combustion, the cause for which is the premature ignition of the air-fuel mixture most frequently occurring in the area of the top dead centre. The knocking combustion is characterized by a faster increase in pressure as compared to normal combustion, and it is a detrimental phenomenon to the engine operation, especially before the top dead centre. The growth speed of the combustion pressure can be correlated with the manner of combustion, which is also evident in the vibroacoustic signal, whose characteristics will undergo changes alongside the combustion speed. The analysis of the remaining work parameters influencing the vibroacoustic signal will enable determining the moments of the knocking combustion occurrence and will thus allow for optimization of the gaseous fuel dose, which directly influences the pollution emission as well as the economical aspect.

Proposal of Reconfigurable Drive System with CVT

This paper presents an analysis of the feasibility of their control system reconfigurable powertrain vehicle using an internal combustion engine and CVT transmission (CVT––Continuously Variable Transmission).

Assessment of Control Dual-Fuel Diesel Engine Affecting the Tendency to Knock

This article discusses the analysis of the control method for LPG injection in compression-ignition engines. The problem of the knocking combustion phenomenon in dual-fuel engines has been described. Determining maximal LPG share which would not induce knocking combustion is difficult based on the scarce amount of information regarding engine parameters. This work presents results of the tests in which an attempt was made to evaluate the impact of particular work parameters of the compression-ignition engine on the tendency of this phenomenon to occur. The engine of the tested vehicle was adjusted to dual-fuel work by installing an additional LPG fitting with injectors located in the intake manifold channels. Analysis of the vibroacoustic signals from laboratory sensors and from commercial sensors applied in spark-ignition engines has been used for the evaluation. The registered signals were subject to frequency analyses; the results of which have been graphically shown and extensively discussed. The tests were conducted at the Automotive Industry Institute (Przemyslowy Instytut Motoryzacji) at the chassis dynamometer in the course of run-up tests or during work with constant load and constant rotational velocity.

Analysis of Operation of Gas Injectors Used in Dual-Fuel Engines with Compression Ignition

The article presents results of the tests of the gas injector used to supply the dual-fuel engines with compression ignition with the LPG addition. The purpose of this research was to determine the actual characteristics of the injector on the basis of the measurement of the mass of portioned gas doses. The experiment assumption was the realisation of the LPG dose, similarly as in the real conditions. The parameters of the gas state, the temperature, pressure, and dose sizes, were such as those observed during the injector’s engine work. Performing the experiment was possible due to the built laboratory stand, designed to enable completion of the above-mentioned tasks. A series of tests was performed, consisting of measurements of the mass of the subsequent gas doses, which allowed for accomplishing the injector’s characteristics. The actual dose was determined and the influence of the injector’s work parameters on changes in the gas flow.

Comparison of spectral analysis of vibration using commercial knock sensor and 3-axis acceleration sensor

With the development of internal combustion engines, engineers attempt to reduce the noise and vibration generated. Due to the high cost of fuel, are increasingly looking for new sources of power in order to reduce costs. In diesel engines, an increasingly popular method is the admixture of propane-butane. This follows because of the price of the fuel as well as to improve the efficiency of combustion. With the development of this type of dual fuel power seems to be a reasonable study of the effects of LPG to generate noise and vibration, as well as an attempt to evaluate the combustion process. Unfortunately, too much addition of LPG causes a phenomenon called knock consisting in abnormal, uneven, explosive combustion of fuels in reciprocating engines. This phenomenon may lead to a reduction in engine performance and permanent damage. Control of the knock detection uses vibration acceleration sensors recording the high frequency ranges. Within the framework of the research conducted by the team of authors, an attempt was made to compare the vibroacoustic signals originating from the commercial knocking sensor with a three-axis acceleration sensor. These signals were subject to a quick Fourier transform in the purpose of analysing the amplitude spectra.