PRINCIPLES GASOLINE/DIESEL FUEL SYSTEMS - OD1620 - LESSON 2/TASK 2
(3) Injector Units (figure 51). Unit injectors combine the injection
pump, the fuel valves, and the nozzle in a single housing. These units
provide a complete and independent injection system for each cylinder. The
units are mounted in the cylinder head with their spray nozzles protruding
into the combustion chamber. A clamp, bolted to the cylinder head and
fitting into a machined recess in each side of the injector, holds the
injector in place in a watercooled copper tube that passes through the
cylinder head. The tapered lower end of the injector seats in the copper
tube, forming a tight seal to withstand the high pressures inside the
cylinder. The injector operates as follows:
(a) Fuel is supplied to the injector through the filter cap.
After passing through a finegrained filter element in the inlet passage, the
fuel fills the annular shaped supply chamber that is created between the
bushing and the spill deflector.
FIGURE 51. UNIT INJECTOR OPERATION.