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High-pressure pumps
The high-pressure pump compresses the fuel and supplies
it in the required quantity. It constantly feeds fuel to the
high-pressure reservoir (rail), thereby maintaining the
system pressure. The required pressure is available even at
low engine speeds, as pressure generation is not linked to
the engine speed. Most common rail systems are equipped
with radial piston pumps. Compact cars also use systems
with individual pumps which operate at a low system
pressure.
Injectors
The injector in a common rail system consists of the nozzle,
an actuator for Piezo injectors or a solenoid valve for solenoid
valve injectors, as well as hydraulic and electrical connections
for actuation of the nozzle needle. It is installed in each
engine cylinder and connected to the rail via a short highpressure pipe. The injector is controlled by the Electronic
Diesel Control (EDC). This ensures that the nozzle needle
is opened or closed by the actuator, be it solenoid valve or
Piezo. Injectors with Piezo actuators are somewhat narrower
and operate at a particularly low noise level. Both variants
demonstrate similarly short switching times and enable preinjection, main injection and secondary injection to ensure
clean and efficient fuel combustion at every operating point.
Conventional injection
Extensive expertise, decades of experience: conventional diesel injection systems
Distributor injection pumps
Small, high-speed diesel engines require an injection system
with high performance, rapid injection sequences, low weight
and a small installation volume. Distributor injection pumps
meet these requirements. They consist of a small, compact
assembly containing the supply pump, high-pressure pump,
and regulation device.
Due to its compact design, the distributor injection pump is
suitable for a variety of applications in cars, light commercial
vehicles, stationary engines, and construction and
agricultural machines (off-highway).
Axial-piston distributor injection pumps for engines with
indirect injection (IDI) generate pressures of up to 350 bar at
the nozzle.
For engines with direct injection (DI), both axial and radialpiston distributor injection pumps are used with peak
pressures of approx. 1950 bar.
| words in action
Axial-piston distributor injection pumps (VE..) are used for
engines with a power output of approx. 30 kW per cylinder,
and radial-piston distributor injection pumps (VR..) with
engines up to 45 kW.
Distributor injection pumps are lubricated with fuel and are
maintenance free.
23
may 2014
Bosch Diesel
No other name is so closely associated with the development and high performance of diesel systems as Bosch. Every single
component reflects the full extent of the company’s diesel expertise.