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The Common Rail System is an accumulator injection
system. The decisive difference to all other forms of
injection system lies in the fact that the
pressurization and injection processes are completely
independent of each other. The Common Rail System's
strategy affords enhanced flexibility for adapting
injection processes to reflect the demands of each
specific application. It serves as the basis for
developing extremely smooth and economical engines
offering impressive levels of dynamic response. |
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The CRS consists of: |
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Low-pressure system with presupply
pump, filter |
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Rail |
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High-pressure pump |
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Injectors |
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ECU with sensors and diagnostic
interface |
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CRS Video |
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Types |
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The first-generation of the Common
Rail System for passenger cars has been designed for
injection pressures
of up to 1350 bar in passenger cars and 1400 bar in
commercial vehicles. |
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The second-generation system reaches
injection pressure as high as 1 600 bar, the third
generation with Piezo injectors even 1 800bar. It also
features a fuel-quantity-controlled pump which, together
with a metering unit, permits fuel delivery to be
adjusted to actual requirements even at low pressures.
Due to its improved efficiency, the new system helps to
improve fuel consumption and reduce fuel temperature. |
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New: the piezo
injector
To control the injection valves, the new Common-Rail
injectors use a rapid-action actuator made of piezo
crystals to control the injection valve. The piezo
crystals expand within an electrical field. The
electronically controlled piezo actuator switches five
times as fast as a solenoid. Bosch has built the
actuator into the body of the injector. The movement of
the piezo package is transmitted non-mechanically - and
therefore entirely without friction - to the rapidly
switching nozzle needle. This doubles the injector's
switching speed, allowing a more precise measurement of
the amount of fuel injected and thus leading to a
reduction in harmful combustion products. |
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Common Rail System
(CRS) for passenger cars |
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Common Rail
System (CRS) for passenger cars |
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Applications: Passenger cars,
light-duty commercial vehicles |
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Power output: 30 kW/cylinder |
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No. of cylinders: 3...8 |
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Control: Electronic, electrical,
solenoid valve, or piezo actors |
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Injection pressure: 1350 bar (1st
gen.), 1600 bar (2nd gen.), 1800 bar (3rd generation
with piezo injectors) |
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Injected fuel quantity: up to 90 mm3
per stroke |
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