The Unit Pump System is a high-pressure fuel-injection system specially designed for commercial vehicles. Series production of the system at Bosch commenced in 1995.
As with the Unit Injector System, each engine cylinder has a single-cylinder pump with integrated solenoid valve. This is connected to a conventional nozzle-holder combination via a short high-pressure line. This construction allows fuel-injection pressures of up to 2,200 bar.
The high-pressure pump is driven directly by the engine camshaft. The pump’s high delivery rate ensures a continuous rise in pressure during the entire duration of the injection.
The injection valves meter the fuel with the help of high-speed solenoid valves. These are triggered by the electronic engine control unit. With variable injection start, variable injection duration, great latitude in adapting to the engine’s operating conditions as well as cylinder-specific correction capabilities, UPS contributes toward environmentally-friendly and fuel-saving engine operation.
The Unit Pump System is used for commercial-vehicle engines with performances of up to 80 kW per cylinder and up to eight cylinders. 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.