Secondary Air System:
Catalytic oxidation reaction requires sufficient oxygen to convert CO and HC into CO2 and H2O, unfortunately, most 2 strokes engine run at the rich air-fuel ratio range from 10-13. Under rich A/F ratio condition, fully catalytic oxidation reaction is prohibited. For most 4-strokes engine, they run at about 13-14.5 under low speed/low load condition, which is slightly lower than stoichiometry. To increase catalytic oxidation reaction, secondary air injecting into the exhaust port/pipe is required. Secondary air system used on 2-strokes engine includes a reed valve and secondary air cleaner. While used on 4-strokes engine, it includes reed valve, secondary air cleaner, and air injection control valve (AICV).
The air flow rate depends on the pressure difference exerted on the reed, spring constant of reed and opening area. LYDS's design covers wide range of engine speed. Sufficient flow rate is necessary for good catalytic conversion especially at high engine speed.
Evaporative Emission Control:
Air pollution can also be caused by unburned fuel that enters the environment through evaporation. During the day, sunlight increases the temperature around the fuel tank, which causes fuel to evaporate into the atmosphere. The polluted air then mixes with hydrogen carbon to create carcinogen precursors, which are damaging to human health. This emission has been regulated by EPA.
LYDS has developed evaporative emission control systems that store fuel vapors in active carbon to prevent their release into the environment. These systems, called carbon canisters, capture fuel vapors and release them to burn out through the engine. One of our goals is to help our children breath fresh air that is free from pollution caused by toxic fuel vapors.