|Tipo di tesi||Tesi di laurea magistrale|
|Titolo||Influenza di fattori di geometrici e di lavorazione sulle rotture a fatica delle valvole motore|
|Titolo in inglese||Influence of geometrical and machining factors on engine valve fatigue failures|
|Struttura||Dipartimento di Ingegneria "Enzo Ferrari"|
|Corso di studi||Ingegneria Del Veicolo (D.M.270/04)|
|Data inizio appello||2020-04-07|
|Disponibilità||Accesso limitato: si può decidere quali file della tesi rendere accessibili. Disponibilità mixed (scegli questa opzione se vuoi rendere inaccessibili tutti i file della tesi o parte di essi)|
|Data di rilascio||2060-04-07|
In questa tesi viene affrontato il problema riscontrato nell’azienda Kohler Engines relativo alla rottura delle valvole motore in alcune applicazioni dei motori Diesel, aspirati e turbocompressi, da loro prodotti.
Focus of the present work is the problem found at Kohler Engines regarding engine valve failure in some applications of their diesel engines, both aspirated and turbocharged. The breakage of the valves in the half-cones retaining grooves causes the valve fungus to detach from its stem, with consequent descent of the fungus into the combustion chamber, thus causing damage to the cylinder and piston. In order to address the problem, the production process of the engine valves at the supplier's plant was first analysed, with the aim of judging the machinery and quality control after each processing, evaluating possible errors during production. Consequently, the extent of the stresses received by the valve during opening and closing was evaluated, investigating with particular attention the possible causes for the generation of the bending moment on the throats. Finally, experimental tests were carried out in order to identify possible solutions to the problem. The tests carried out in the company, fatigue life, metrological and chemical composition analysis, engine cycles, involved valves with different surface finishes in the grooves fixing the half-cones, in order to limit as much as possible cracks due to a coarse finish. In order to carry out the tests, the machinery used, the most critical engine cycles were analysed in detail, as well as the technical specifications required by Kohler Engines regarding test methods and performance requirements for components mounted on its engines were analysed in detail.