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...

As mechanical efficiency has great relevance in the alternative engine performance, the authors research in the development of testing facilities to characterize the sources of engine mechanical losses. The present paper deals with the realization of a hardware platform to conduct experimental studies in small combustion engines to experimentally characterize the mechanical losses of a single-cylinder internal combustion engine by means of the indicated diagram and motoring methods. The system was completed by means of an electrical motor-generator coupled to a single-cylinder air-cooled spark ignition engine, a self-developed electronic hardware control, and a PC-based instrumentation and data acquisition system. Specifications of load-motoring-starting system, including the description of the proprietary electronic load regulation system, are detailed. Also, the instrumentation system of in-cylinder and intake pressures; Temperatures of intake air, exhaust gases, lubricant oil, and engine block; effective torque and crankshaft position are described, including the signal acquisition system. The methodologies for indicated diagram and motoring method are described, mentioning the required measurements to apply each method and the engine load-temperature considerations when an engine is tested in fired or motored conditions. The platform was used to study the mechanical losses of the engine under motored and fired conditions under a wide range of rotational speeds and throttle openings, allowing to draw conclusions about the operating features of the developed test bench in itself, and also about the mechanical losses of the engine tested. Initially, samples of cylinder pressure, torque, intake pressure as function of crank angle and indicate diagram were obtained, showing similar waveforms present in related literature. Then, variations of the aforementioned temperatures against rotation speed and throttle opening and results for the mechanical losses determined by indicated diagram and motoring methods are shown. Finally, two empirical correlations are proposed to estimate the mechanical losses. In the future the hardware platform will be utilized to investigate in-cylinder engine parameters, detailed thermal and mechanical engine performance

This paper envisages studying the features of a conventional inductive ignition system along with its MOSFET and IGBT-based transistorized modifications. The influence of mechanical contact breaker dynamics and ignition coil characteristics on the current and voltage waveforms of the primary and secondary circuits of these studied ignition systems are mathematically and experimentally exposed. The investigation is considered necessary prior to attempting subsequent modeling and diagnostics procedures on the current-voltage performance characteristics of conventional and transistorized ignition systems. The work has demanded the development of an experimental setup based on a basic modifiable ignition system mockup and an instrumentation system to measure and analyze the voltage-current parameters of inductive ignition systems. The paper describes the design details of such instrumentation system, presents mechanical and electrical models for contact breaker and ignition circuits, then simulated to obtain base free-run response waveforms and electrical continuity behavior of the contact. A test of frequency response of the ignition coil provided additional input to the model. An experimental test of continuity of the contact, in agreement with its model, shed light on the actual excitation of the primary coil. The work comments on a sample of the registered current and voltage waveforms in primary and secondary coil windings of the ignition system at atmospheric conditions. Comparisons of waveforms and energy for mechanical contact, MOSFET and IGBT switches are made to establish them as a reference for future tests.

Dentro de las vías de disipación de la energía de los motores de combustión interna (MCI) se encuentran las pérdidas mecánicas, en adelante FMEP (friction mean efective pressure), las cuales representan cerca del 12% en promedio de la energía provista por el combustible para las diferentes condiciones de operación y cuya reducción es una alternativa para incrementar la eficiencia de los motores y reducir el consumo de combustible, el desgaste, y las emisiones de dióxido de carbono. En este trabajo se describen algunos fundamentos conceptuales sobre la FMEP de los MCI alternativos, como antesala para abordar una revisión del estado del arte relacionado con el estudio experimental y el modelado de estas pérdidas. Inicialmente se dedica una sección del documento para exponer las componentes principales de la FMEP en MCI, mencionando la naturaleza y las fuentes de la fricción, el bombeo y las pérdidas auxiliares, además de las variaciones de estas con el cambio del régimen de giro y el nivel de carga. Adicionalmente se mencionan algunas alternativas mediante las que se puede disminuir cada componente de pérdidas. En la sección consecutiva, se presentan los diferentes métodos de determinación experimental de la FMEP, mencionando las particularidades, las variables cuya medición es requerida y las consideraciones sobre los resultados de cada uno y detallando las condiciones de operación en cuanto a régimen de giro y nivel de carga del motor de prueba, especificando la presencia o ausencia del proceso de combustión y mencionando el tipo de MCI que puede caracterizarse al aplicar cada método. Finalmente, se presenta una sección en la que se describen diferentes modelos para calcular la FMEP de los MCI mencionando el tipo de modelo y los pares cinemáticos analizados. Adicionalmente, de cada modelo se comenta si es utilizable bajo régimen de operación estacionario o si posibilita la predicción del desempeño mecánico en estado transitorio. Se compila un listado de modelos de la FMEP.