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Considerations for starting combustion engines with AC machines

Monroy Mauricio, Romero Carlos A., Henao Edison

Diagnostyka

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2023

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Vol. 24, No. 1

art. no. 2023102

EN

To initiate its combustion cycles, internal combustion engines require a minimum rotational speed that can be given from several sources (muscular, electrical, pneumatic, among others). Advantages of initiating an ICE with an AC electrical machine is that it can integrate starter motor and generator in one device, provide a linear ramp of acceleration when starting, and assist the ICE in torque production. This article illustrates considerations for the design of a starting system with an AC electrical machine. Initially, criteria of torque, rotational speed and power requirements are analysed, considering resistances of compression, friction, and inertia of the slider-crank mechanism, as well as accessories, with a preliminary experimental validation. Also, types of three-phase AC electrical machines are put to comparison, as well as their associated electronic components needed for driving them in each case, concluding that AC induction machines require a complex 4-quadrant inverter. PM synchronous machines require a simpler inverter, but with highly specified power electronics components. The classical wound rotor machine requires the simplest inverter, with unidirectional power flow, less power transfer losses and less critical power electronics components. Finally, considerations for using of a battery assisted with supercapacitor as complementary DC power source are made.

2

A methodology for non-invasive diagnosis of diesel engines through characteristics of starter system performance

Ramírez Juan D., Romero Carlos A., Mejía Juan C., Quintero Héctor F.

Diagnostyka

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2022

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Vol. 23, No. 2

art. no. 2022202

EN

In this work, a methodology to diagnose ten diesel bus engines is carried out by means of some characteristics of the starting system performance. The signals of battery voltage, electric current supplied to the starter motor and crankshaft revolutions during cold and warm engine starting processes are analysed. Characteristics and patterns of the signals that are attributable to engine compression and combustion failures are pointed out, which are related to the kilometres travelled by each vehicle after the last engine repair and the shutdown time of the engine in warm condition. It is obtained that the rise of the current required by the starter motor during the second and third compression process, and the mean crankshaft angular acceleration after the second compression process are characteristics that are related to the engine condition.

3

Experimental study of mechanical losses of single-cylinder spark-ignited engine

Romero Carlos A., Henao Edison, Ramírez Juan

Diagnostyka

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2021

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Vol. 22, No. 3

13--24

EN

In this study, the mechanical losses of a single-cylinder spark-ignited Robin EY15 engine were experimentally determined and analysed by the indicated method. The effects of the load and speed on the mechanical loss balance were also analysed. The tests were conducted on a test bench equipped with a DC motor generator at speeds between 1500 and 4800 min-1 and three load levels of 25, 50, and 100%. The results showed that the mechanical efficiency ranges between 22.5% and 83.2% for the tested engine and the evaluated operation points, attaining the highest efficiency under the full load and 2100 min-1. However, at this load level, the efficiency is reduced to 29% with the increase in the rotation speed. Concurrently, the pumping losses contribute up to 58.7% of the total losses, which indicates that their contribution is even higher than the sum of the other components under low load conditions. However, as the load increases, this contribution decreases to 18% for lower rotation regimes. In addition, the experimental results of the total mechanical losses were compared with some numerical correlations found in the literature. Finally, some empirical correlations were proposed for the mechanical efficiency calculation of the tested engine.

4

Detection of ice states from mechanical vibrations using entropy measurements and machine learning algorithms

Mejía Juan C., Quintero Héctor F., Echeverry-Correa Julián D., Romero Carlos A.

Diagnostyka

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2020

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Vol. 21, No. 4

87--94

EN

Entropy measurements are an accessible tool to perform irregularity and uncertainty measurements present in time series. Particularly in the area of signal processing, Multiscale Permutation Entropy (MPE) is presented as a characterization methodology capable of measuring randomness and non-linear dynamics present in non-stationary signals, such as mechanical vibrations. In this article, we present a robust methodology based on MPE for detection of Internal Combustion Engine (ICE) states. The MPE is combined with Principal Component Analysis (PCA) as a technique for visualization and feature selection and KNearest Neighbors (KNN) as a supervised classifier. The proposed methodology is validated by comparing accuracy and computation time with others presented in the literature. The results allow to appreciate a high effectiveness in the detection of failures in bearings (experiment 1) and ICE states (experiment 2) with a low computational consumption.