An Improved Model for Predicting Reed Valve Behaviour in Two-Stroke Cycle Engines

Previous publications from The Queen's University of Belfast have shown the formulation of a mathematical model to simulate the dynamic behaviour of a reed valve as used between the crankcase and inlet tract of a simple two-stroke cycle engine. This paper describes the enhancements and improvements made to this original reed valve model and its verification by correlation with measurements from a firing engine. Measured and predicted data for reed tip lift and delivery ratio are presented for a 350cm³, twin cylinder test engine over a wide range of engine speeds up to 9500 rev/min. The results of this experimental and theoretical study, using varied reed width profiles and radically different reed petal materials including carbon fibre, glass fibre reinforced plastics and steel, are also presented. The development of a new and unique reed valve visualisation technique is described and discussed both theoretically and practically. Therefore a more complete and wide ranging simulation of a two-stroke cycle engine fitted with a reed intake valve is now possible.