Two Stroke Engine Using Reed Valves

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INTRODUCTION

In developing countries a large number of private vehicles used two stroke engines. A large percentage of them employ two stroke engines because of their simplicity, high power to weight ratio and low cost of maintenance. Although two stroke engines are less efficient and more polluting they may continue to popular due to low cost and maintenance.


PROPOSAL FOR MODIFICATION

In the existing engine, the air fuel mixture is induced in the crank case when the piston is at the top dead centre. From these the piston moves down, uncovers the exhaust port first and then the transfer port which contains slightly compressed charge at a pressure of about 130 kpa.This charge is transferred to the upper part of the cylinder through the transfer port.


REED VALVES

A pair of reed valves was employed to introduce the air from out side to the top of transfer passages that would remain between the crank case content of live mixture and the closed transfer port to the cylinder. When the later opened, air would be pumped in a head of mixture forming a buffer screen of air between the burned gas and the fresh charge.



PRINCIPLE OF OPERATION

In the improved design two reed valves are fitted at the upper end of transfer duct connecting the crank case and the cylinder as shown in fig.2. The reed valves are positioned in such a way that air would enter in a direction perpendicular to the cylinder axis and along its radius