Page 239 - 05. Subyek Teknik Mesin - Automobile Mechanical and Electrical Systems Automotive Technology Vehicle Maintenance and Repair (Vehicle Maintenance Repr Nv2) by Tom Denton

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Engine systems 223

Figure 2.291 Direct injection (DI) injector
2 1 4

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5
6

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9 10 11
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Figure 2.292 Electronic diesel control (EDC) rotary pump system: 1, engine ECU; 2, glow control
unit; 3, fi lter; 4, air-mass meter; 5, injectors; 6, glow plugs; 7, rotary distributor pump with ECU; 8,
alternator; 9, coolant temperature sensor; 10, crankshaft sensor; 11, throttle pedal sensor
injector needle. The hydraulic pressure is applied to a face on the needle where Key fact
it sits in a pressure chamber. The fuel pressure needed is in excess of 100 bar
(1500 psi). This pressure lifts the needle and opens the nozzle, so that fuel is The fuel pressure needed to open
the fuel injector is in excess of 100
injected in a fi ne spray pattern into the combustion chamber.
bar (1500 psi).
The next section examines the Bosch rotary pump electronic diesel control
system, while the section after that looks at the system now in use on most
modern cars: common rail direct injection.

2.5.3.1 Rotary pump system
Bosch rotary VR pumps are used on high-speed direct injection diesel engines
for cars and light commercial vehicles ( Fig. 2.292 ). They are radial-piston
distributor injection pumps having opposing plungers that are forced inwards by