Woodward's MFI systems regulate fuel injection quantity by the use of a helix on a fuel pump plunger driven from the engine camshaft. These cam-driven unit pump and injector systems generate high pressure to meet the specific performance, reliability, and durability of many engine builders.
Woodward’s mechanical unit pump systems operate on most fuel types including heavy fuel oil (HFO), marine diesel oil (MDO), bio, and diesel fuels.
Woodward also develops mechanical unit fuel injection (MUI) systems where the fuel pump and injector are combined into a single unit.
Pump-pipe-Injector systems (also known as Unit Pump systems) are the traditional form of high pressure fuel injection systems used on large industrial high and medium speed diesel engines. Each cylinder of the engine incorporates a single high pressure pump and injection separated by a high pressure pipe. The fuel pump is connected either directly out through a roller/push rod mechanism to the engine fuel camshaft. The rotation of the fuel camshaft with its elliptically shaped cam lobe allows a plunger within the high pressure pump to rise and fall. During the “rising” phase of the plunger stroke the plunger squeezes fuel that has enter the fuel pump through ports above the plunger. The “squeezing” of the fuel creates the high injection pressures characteristic of diesel fuel injection systems. The amount of fuel that is injected is controlled by the rotary position of a specifically designed helix that is machined into the pump plunger that in turn is connected to the engine governor through a linkage system.
The pressured fuel is injected into the engine's cylinder through the high pressure injector. The high pressure injector uses a group of small orifices or “spray holes” that distribute the high pressure fuel into the engine's cylinder chamber in a specifically designed pattern to fit the engine's performance and emissions requirements.
Woodward’s mechanically controlled Pump-pipe-Injector systems are designed for use on a wide range of applications using multiple fuel types including HFO (heavy fuel oil) where cooling of the injector could be incorporated into the design to regulator fuel temperatures.