Miniaturized Cylinder Head Production by Rapid Prototyping

Topics: Internal combustion engine, Cylinder head, Rapid prototyping Pages: 11 (3354 words) Published: August 27, 2013
Proceedings of COBEM 2009 Copyright © 2009 by ABCM

20th International Congress of Mechanical Engineering November 15-20, 2009, Gramado, RS, Brazil

MINIATURISED CYLINDER HEAD PRODUCTION BY RAPID PROTOTYPING
MELO, Rodrigo N., a42144@alunos.uminho.pt
Universidade do Minho, Campus de Azurem, 4800-085 Guimarães, Portugal.

MONTEIRO, António A.C., cmonteiro@dem.uminho.pt Universidade do Minho, Campus de Azurem, 4800-085 Guimarães, Portugal MARTINS, Jorge J.G., jmartins@dem.uminho.pt Universidade do Minho, Campus de Azurem, 4800-085 Guimarães, Portugal.

COENE, Stijn, stijnxcoene@hotmail.com
Universidade do Minho, Campus de Azurem, 4800-085 Guimarães, Portugal.

PUGA, Helder F., puga@dem.uminho.pt
Universidade do Minho, Campus de Azurem, 4800-085 Guimarães, Portugal.

BARBOSA, José J.C., kim@dem.uminho.pt
Universidade do Minho, Campus de Azurem, 4800-085 Guimarães, Portugal.

Abstract. This work shows the development of the design and manufacturing of a very small engine, namely its head. The engine works under the 4-stroke cycle, therefore having a very complex cylinder head, housing the camshaft, valves and its auxiliaries (seats, guides, springs), spark plug, inlet and exhaust passages and a coolant chamber. The geometries, both inner and outer are highly intricate which makes the production of such a part a very difficult job. In addition, when the engine is very small, as it is the case of this engine, all dimensions are miniaturized therefore making it extremely difficult to design, cast and finish. The cooling chamber, in particular, has a critical inner core removal problem due to reduced accessibility, imposing casting limitations. The cores place also a problem of air and gas removal during metal filling and solidification. Rapid prototyping may be the only solution to build the cores, and may help in the design and manufacturing phases of the casting tools. 3D printing with a plaster based material as a rapid prototyping technique presents itself as a tool to drastically reduce the design-development-casting process effort and time cycle. This technique enables the designer to obtain new moulds for castings on the shortest time possible, following redesign and new casting simulations. This paper illustrates the various tasks involved in the design and development stages leading to the production of a running prototype of the cylinder head for this small engine. Keywords: Engine design; Casting design; Rapid Prototyping; 3D printing; Casting simulation 1. INTRODUCTION Different rapid prototyping techniques were applied to the development and manufacture of a cylinder head to be used on a small engine intended for a fuel consumption marathon. The various stages of development are herein presented and discussed. The design should incorporate various characteristics and features intended to maximise the efficiency of the engine. The head should be of the hemispherical type with two inclined valves, and should have squish area, OHC, a sufficiently large volume coolant chamber and a swirl producing inlet passage. All this should be included in a 10x10x14 cm envelope. The first designs and models produced by rapid prototyping explored the design features, such as the design constrains and potential for miniaturization and manufacture. Later, various features were optimized in terms of operation (swirl generation, pressure loss) and in terms of manufacture (mould production, wall thickness, casting behaviour and machining). The final design combines the required levels of swirl generation (by the inlet track) and coolant volume, with the potential of manufacture of a very complex component with sufficient precision. Some of the various interim design changes and optimisations are described, which led to the final specification. 1.1. Shell Eco-Marathon An international competition for fuel consumption is organised every year by Shell, called Eco-Marathon. This year, 2009, the race comprised 8 laps to the...

References: Barbosa, J., Monteiro, A., Pais, M. (1999), “Análise Crítica da Evolução da Fundição”; 1ro Congresso LusoMoçambicano, Maputo, Moçambique Coene, S. (2008) “Inlet Design for Optimal Swirl in an IC Engine”, MSc thesis, University of Minho, Portugal Dickens, P.M., et al (1995), “Conversion of RP Models to investment Castings, Rapid Prototyping Journal, 1:4, 4-11. The cost-effectiveness of the process suits best high complexity small parts and low quantities, which are typical of both technologies Heywood, J.B. (1988), “Internal Combustion Engine Fundamentals”, McGraw-Hill, 1988 Saraiva, V., Lima, M, Monteiro, A., Pouzada, S. (2002), “A Study on the Application of Investment Casting to Injection Moulds”, RPD (2002) – Advanced Solutions and Development, Marinha Grande, Portugal Stone, R. (1989) “Motor Vehicle Fuel Economy”, Middlesex (England), Macmillan education LTD, 6. RESPONSIBILITY NOTICE The author(s) is (are) the only responsible for the printed material included in this paper.
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