The Unit Injector System (UIS) has been on the market since 1994. The system combines the injection nozzle and the high-pressure pump in a single assembly. One such Unit Injector is fitted in the head of each engine cylinder. The high pressure is built up by the activation of the pump plunger of the Unit Injector by the engine camshaft via a tappet or rocker arm.
The advantage of the Unit Injector System is that there is no high-pressure line between the high-pressure pump and the injection nozzle. This means that the UIS can build up extremely high injection pressures: 1,600 bar in the first generation of the system, 2,200 bar in the current generation. This not only leads to low emissions but also increases efficiency.
The injection nozzle operates with a rapid-switching solenoid valve which is triggered electronically. It can produce a pilot injection which reduces engine noise.
It is mainly employed in heavy and medium-sized commercial vehicles with performances of up to 80 kW per cylinder. The electronic control unit can trigger a system comprising a maximum of eight cylinders. A second control unit allows the system to be extended to 16 cylinders.
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.
