Perkembangan Sistem Bahan Bakar Motor Bensin

Proses Penyemprotan Bahan Bakar Pada Mesin DI Terjadi dua Tahap yaitu saat langkah hisap dan kompresi

Tujuan untuk menghasilkan campuran yang homogen

Hisap Akhir Hisap, Injektor menyemprotkan BB

Kompresi, Injektor mengabutkan BB

Percikan Api pada busi dan pembakaran

Perbedaan Proses

MPI dengan DI

Pola Aliran Di Dalam Silinder Pada Mesin Multi Valve

Proses Pembakaran Pada Mesin Direct Injection

                                                                                                                      

Perbedaan Bentuk Kabutan pada Injektor Model Compact dan Model Cone

Fuel injection mode mapAt speeds up to 120 km/h, the Mitsubishi GDI engine operates in Ultra-Lean Combustion Mode. At high speeds or under heavy loads, it automatically switches to Superior Output Mode. It switches to Two-Stage Mixing for hard acceleration from standing starts or low speeds.

4G93 GDI engine schematicPrecise control of both airflow and fuel delivery are crucial to the engine's success.

Why does it have to be clockwise?

If the air tumbles counter-clockwise, it will carry a directly injected

fuel spray into the sparkplug, creating a soot buildup that leads to

misfires. Also, counter-clockwise flow doesn't allow time for a

directly injected spray of petrol to vaporise. These problems were

solved by the invention of the Upright Straight Intake Ports, which

enabled "clockwise tumble."

Mitsubishi spent years of research to determine the most efficient pattern of in-cylinder airflow. The patented "clockwise tumble" flow of the Mitsubishi GDI engine is the result.

Tumble vs. SwirlConventional engines create "swirl" airflow. But this takes the fuel around the outside of the cylinder. It's impossible to concentrate the fuel, so it doesn't always burn completely.Tumble-shaped airflow solves this problem. The tumble shape breaks up as the cylinder compresses, forming small typhoon-like eddies. These enable fuel to be concentrated around the sparkplug, for outstanding combustion efficiency even with extremely lean air-fuel ratios.A tumble pattern was employed on the Mitsubishi Vertical Vortex (MVV) lean-burn engine. However, counter-clockwise tumble was not feasible for direct injection.

In this mode, at speeds up to 120 km/h, the Mitsubishi GDI engine achieves complete combustion with an air-fuel ratio of 40:1.

Conventional engines: 14.7:1Lean-burn engines: 22:1Mitsubishi GDI engine: 40:1.

Late in the compression stroke, the High-Pressure Swirl Injector sprays fuel in a tight, swirling spiral towards the piston top. This spiral and the "clockwise tumble" airflow keep the fuel spray concentrated around the sparkplug. When the sparkplug ignites, a powerful firestorm is controlled by the spherical cavity. No fuel is wasted. The result: a 20% improvement in overall fuel economy.

Ultra-Lean Combustion Mode1. Piston moves downward. / 2. Piston reaches bottom and begins compression stroke.3.Fuel is injected late in compression stroke. / 4. Sparkplug ignites mixture.

In this mode, fuel is injected during the intake stroke in a lengthy, cone-shaped spray to cool the cylinder through evaporation.By preventing knocking through the cooling effect, the 4G93 GDI engine can run at a compression ratio of 12.5, for outstanding power and torque.Furthermore, its high volumetric efficiency creates an effect similar to that of a supercharger.The result: output and torque superior to conventional engines.Superior Output Mode

1. Piston moves downward.2. Fuel is injected.3. Piston moves up.4. Sparkplug ignites mixture.

                                                                                                                      

This mode was developed specifically for the European 4G93 GDI.Fuel is injected twice: a small amount early, and the majority late.Early injection cools the cylinder. The air-fuel ratio at this point is extremely lean, up to 60:1, so it does not spontaneously ignite.When the rest of the fuel is injected, the air-fuel mixture becomes very rich - about 12:1. This rich mixture is completely combusted.The result: at 650 rpm, a 55 percent increase in torque, for the power to pull away fast.

Two-Stage Mixing1. Piston moves downward.2. Fuel is injected.3. Fuel is injected again during compression stroke.4. Sparkplug ignites mixture.

Perbedaan Konsumsi Bahan Bakar antara Mesin Bensin dan Diesel