Nestor Rodriguez-Amaya

Unit pump system (UPS)

The unit pump system (UPS) is used in commercial vehicles and large engines. The unit pump (UP) works in the same way as the unit injector (UI) for commercial vehicles. In contrast to the UI, however, the nozzle and the injector are kept separate in the UP and connected to each other by a short line.

Unit injector system (UIS)

In the unit injector system (UIS), the fuelinjection pump, high-pressure solenoid valve and injection nozzle form a single unit. The compact construction – with very short high-pressure lines integrated in the component between pump and nozzle – makes it easier to deliver higher injection pressures compared with other fuel-injection systems because the compression volume 1) and thus the compression losses are lower. The peak pressure in the UIS currently varies, depending on the type of pump, between 1,800 and 2,200 bar.