DYNA JOURNAL ENGINEERING

Key words:

Motor, Rendimiento, Relación diámetro / recorrido, Rozamiento, Perdidas térmicas, Hipocicloide, Relación de compresión variable, Engine, Efficiency, Ratio Diameter / Stroke, Friction, Thermal lost, Epicycloid, Variable compress ratio..

Article type:

ARTICULO DE INVESTIGACION / RESEARCH ARTICLE

Section:

VARIOUS

ABSTRACT
The amount of petrol is limited and in Europe we have a great dependence of petrol for getting the energy needed, especially for cars and trucks, being very difficult the replacement by other fuels. Also we have the problem of the CO2 produced when we burn the petrol, because of this, all we can made for reducing the consume of the engines,must be welcome. I know that in the design of the engines has been made a good job.There are a big difference between the consumption of the nowadays engines and the ten years old ones. The efficiency of a engine, may be expressed as the result of multiplying many factors, one of then is the mechanical efficiency. This mechanical efficiency is mainly due to lost of energy that the frictions inside the engine mean. The present days system of crankshaft, piston rod, and piston have two inconvenient, one of then is the existing radial force between the piston and the cylinder, this mean friction and wear; other is that the ratio between the diameter / stroke must be high, in order to avoid long piston rods and high engines.There are almost one system for getting the axle of de piston rod been always the same of the cylinder, these system also get a simple harmonic movement, let say that the function giving his position versus the time is a sinusoid. This article is based in the substitution of the crankshaft by a diametric hypocycloidal system and the advantages of this system versus the nowadays system. The ratio piston diameter / stroke of a engine is very important, a high ratio is god for getting high specific power (Kw/l) but getting low efficiency, these mean high consumption of fuel each unit of energy get. Other reason for thinking in use alow ratio diameter / stroke is the thermal lost, that is function of this ratio and has the minimum value with lower ratios that nowadays are usual. The present work studies a possible system to attain such a low ratio, that have advantages over the usual systems.
Key words: Engine,Efficiency, Ratio Diameter / Stroke, Friction,Thermal lost, Epicycloid, Variable compress ratio.