The Unit Injector-System (UIS) is a system for diesel direct injection. This technology is also known as the pump-nozzle system. In 1994 Bosch supplied he world's first UIS for commercial vehicles. Its special feature is that it combines the injection pump and injection nozzle in one unit (Unit Injector).
Bosch employs Unit Injector Systems particularly in heavy and medium-sized commercial vehicles with performances of up to 80 kW per cylinder and up to eight cylinders. If two control units are used, this technology is also suitable for engines with up to 16 cylinders.
Unit Pump System (UPS)
The Unit Pump System (UPS) is a system for diesel direct injection. It is closely related to the Unit Injector System (UIS) and is exclusively available for commercial vehicles. Bosch was the world's first manufacturer to market this technology, also known as the "Unit Pump System", in 1995.
The feature of the UPS is that each engine cylinder has a unit pump of its own. This consists of the high-pressure pump with integrated solenoid valve, a short injection fuel-injection line, a pressure-delivery connection and a conventional nozzle-and-holder assembly.
The advantage of this system: it permits injection pressures of up to 2,200 bar. In addition, conversion from injection systems with traditional in-line or distributor fuel-injection pumps does not require complete redesign of the cylinder head. Engine manufacturers save development costs. A further advantage: damaged pump/valve units are simple to exchange.
Bosch uses Unit Pump Systems particularly in commercial vehicle engines with performances of up to 92 kW per cylinder and with four to 18 cylinders. A second control unit is required if the number of cylinders exceeds eight.