Effect of various ignition timings on combustion process and performance of gasoline engine

This article deals with the effect of the ignition timing on the output parameters of a spark-ignition engine. The main assessed parameters include the output parameters of the engine (engine power and torque), cylinder pressure variation, heat generation and burn rate. However, the article also discusses the effect of the ignition timing on the temperature of exhaust gases, the indicated mean effective pressure, the combustion duration, combustion stability, etc. All measurements were performed in an engine test room in the Department of Technology and Automobile Transport at Mendel University in Brno, on a four-cylinder AUDI engine with a maximum power of 110 kW, as indicated by the manufacturer. To control and change the ignition timing of the engine, a fully programmable Magneti Marelli control unit was used. The experimental measurements were performed on 8 different ignition timings, from 18 CA to 32 CA BTDC at wide throttle open and a constant engine speed (2500 rpm), with a stoichiometric mixture fraction. The measurement results showed that as the ignition timing increases, the engine power and torque also increase. The increase in these parameters is a reflection of higher pressure in the cylinder, the maximum value of which is achieved at a higher ignition timing near top dead centre in thepower stroke. In these conditions we can expect higher engine efficiency. It was also found that the combustion is more stable with a higher value of ignition timing. No significant difference was found in the combustion duration.O

Conceptual Design of Electromechanical Systems Using Ferrofluids

This paper presents an overview of a newconceptual design of electromechanical systems usingferromagnetic liquids. Idea of the new concept is explained,advantages and disadvantages of such systems are discussedand three illustrative examples are presented. Numericalsimulations and experiments on real devices are employed tostudy properties of these systems

The impact of upper link length on the output parameters of a tractor set

The aim of the article is to find out the impact of the increase in the force in the upper link of a three-point hitch on the performance parameters of the tractor set Claas Arion and the carried plough Pöttinger equipped with a traction roller and the cultivator Väderstad. During aggregation of the tractor with the plough with an average increase in the force in the upper link of a three-point hitch by 25 kN, a decrease of slippage in average by 8.25 %, a decrease in fuel consumption by 1.875 ml / m3 and an increase in effective performance by 0,225 m3 / s were achieved. During aggregation of the same tractor with the carried cultivator with an increase in the force by 40 kN, an average decrease in slippage by 2.64 %, a decrease in effective fuel consumption by 2 l / ha and an increase in effective performance by 0.6 ha / h were achieved. The changes in the observed parameters were demonstrably influenced by the change in the force in the upper link, which was more significantly shown during the aggregation of the tractor with the plough equipped with a traction booster.O

TEM investigation of MoSeC films

Transition metal dichalcogenides (TMD) are widely used as self-lubricating material either as oil additive or directly as thin films. Magnetron sputtering is a deposition method allowing depositing such films with high density and adhesion. However, their spread use in practical applications is still hindered since their excellent sliding properties are deteriorated in the presence of humidity and under high contact pressures. MoSe2, one of the members of TMD family recently studied, has been co-sputtered with carbon in order to improve the mechanical and tribological properties when compared to pure MoSe2 film

On magnetic fluid particles dynamics investigation

This paper deals with the investigation of the dynamics of magnetorheological fluid. The response of ferromagnetic particles to changes in external magnetic field is observed with the use of high speed camera. Optically obtained data are processed with the use of scientific tool ImageJ. Functions and limit values of the particles dynamics are determined with the use of statistic methods afterwards

Drawbar Pull and Its Effect on the Weight Distribution of a Tractor

This article aims to experimentally determine how the tractor's weight distribution changes during loading by drawbar pull, and how the tractor's weight affects its drawbar pull properties. Drive wheel ballasting has a significant effect on the drawbar pull and wheel slip of the tractor - travelling gear losses. To achieve these objectives, we conducted experimental measurements on the tractor Case IH Magnum 370 CVX. The results show that higher drawbar pull is achieved in tractors with a higher weight. The measured increase of drawbar pull was 15,8 kN between maximal and minimal weight (Δ 2320 kg). All variants show an equal percentage increase in the weight on the rear axle of the tractor (+ 6 %). Increasing the tractor's weight affected the drawbar pull as well as the wheel slip. As the tractor's weight increases, there is a smaller increase in wheel slip as the drawbar pull increases. The results confirmed that tractor ballasting is important in order to achieve optimum drawbar pull properties, but it is necessary to keep in mind that the higher the weight of the machine or equipment, the larger the effect on the soil.O