Unit Injectors - Volvo EPA2007 D13F Reference Manual

98 ENGINE COMPONENT AND LOCATION

Unit Injectors

1. Injector Yoke
2. Copper Sleeve
3. O-Ring
4. Fuel Gallery
5. O-Ring
6. O-Ring
7. Pressure Relief Valve
This engine uses double solenoid unit injectors. Unlike systems that require separate
components for delivering, pressurizing and injecting, this unit injector combines
these functions. These injectors precisely control the fuel delivery because of the two
solenoids. The solenoids, pump and nozzle are in a single body in close proximity
to each other.
The injector is set in a pressurized fuel gallery where the fuel temperature is constant.
Uniform fuel temperature means uniform quantity in each injection which means
uniform power output from each cylinder.
The fuel pump pressurizes the gallery so that fuel rushes into each injector when it
opens. Gallery pressure is regulated by a valve that delivers excess fuel back to the
tank.
Copper sleeves, acting as coolant jackets, line the bottoms of the injector bores.
Engine coolant circulates around these sleeves aiding the process of controlling
injection temperature.
8. Solenoid Coil
9. Solenoid Coil
10. Injector Valve
11. Injector Piston
12. Injector Nozzle
13. Washer
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