SCIP : a New Simplified Camless IAPAC Direct Injection for Low Emission Small Two-Stroke Engines 978455

The IAPAC Direct fuel Injection (DI) system, developed by IFP, has already well proven its capability to reduce pollutants emissions and fuel consumption of 2-stroke engine. This crankcase Compressed Air Assisted Fuel Injection Process allowing the introduction of the fuel separately from the scavenging air, minimizes the fuel short-circuiting.

In earlier works, results of the implementation of the IAPAC system on cylinder displacement from 125 cc to 400 cc have been presented in various papers. These first prototypes were all using a camshaft to drive the IAPAC DI poppet valve, which was considered as a limitation for applying this system to small displacement 2-stroke engines.

The new SCIP system is no more using a camshaft. The IAPAC poppet valve used for low pressure air assisted fuel atomization and in-cylinder injection, is here actuated by a diaphragm and the lift of the valve is controlled by pressures from the engine. This system doesn't require any cam or driveshaft, or any electric power supply to drive the DI air assisted injection valve. Its camless air assisted injector unit can be easily bolt on existing 2-stroke cylinder heads with minimum engine intrusion and almost no engine design modifications.

The first development tests have been carried out on a 125 cc 2-stroke scooter engine and have shown a significant reduction of pollutants emissions and fuel consumption, demonstrating the SCIP capability to meet the marine outboard US EPA 2006 emissions legislation. Endurance testing was also performed to confirm the durability characteristics of this new system.

More recent results obtained on a 50 cc demonstration scooter vehicle, have shown the capability of this new system to meet the European 1999 Stage 1 emissions regulation without catalyst, and Stage 2 with a small oxidation catalyst, while maintaining typical 50 cc scooter driveability and performance characteristics with engine speeds up to about 10000 RPM.

Therefore the SCIP system appears as a simple, highly efficient and easy way to reduce pollutants emissions and fuel consumption of small 2-stroke engines of cylinder displacement from 20 to more than 150 cc.