Maintenance manual for sunray hfc4da1-2c china-IV diesel engines
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The space of the common rail is always filled with high
pressure fuel. It utilizes the fuel compressed due to high
pressure to achieve the accumulator effect. When the fuel is
departed from the common rail for injection, the pressure in the
high pressure accumulator is basically constant. At the same
time, the pressure variation generated by the pulsed fuel supply
of high pressure pump is balanced and the pressure information
is provided to the ECU.
IV. High pressure fuel pipe
The high pressure fuel pipe is used to convey the high pressure
fuel and is made of steel to endure the intermittent high
frequency pressure variation under the maximum system pressure of the engine. The fuel pipe is generally 6mm in
outside diameter and 2.4mm in inside diameter. All high pressure fuel pipes between fuel rail and fuel injectors are
same in length, which means that the distances between the fuel rail and all fuel injectors are the same and the bending
points compensate the corresponding length differences.
IV. Fuel injector
The fuel injectors are the core parts of the high pressure common rail and are installed on the high pressure common
rail. In accordance with the directive of the ECU, the fuel
injectors spray high pressure well-atomized fuel into the
combustion chamber at specified moment and specified
pressure for a specified duration.
The fuel injector is mainly composed of fuel injector
nozzle, hydraulic servo unit, and solenoid valve. When
the coil control valve acquires control signal through the
ECU, the control valve will depart from its seat ring so
that the fuel pressure in the needle valve control chamber
drops rapidly. As the pressure at the injector nozzle holder
is maintained at similar pressure with common rail, the
needle valve opens and the injection starts. When the
current of the solenoid control valve drops to zero, as the
control valve returns to the seat cushion under the
application of coil spring, the pressure of the needle
control chamber will increase to lightly higher than he
pressure at the injector holder so that the needle valve
closes the injector and the injection stops. The sealing
copper washer beneath the fuel injector must be replaced
once the fuel injector is disassembled or loosened. During
the disassembly, use the special tools recommended or
designated by JAC Multifunctional Commercial Vehicle
Company. Note: Never disassemble the fuel injector by
self in any case. All maintenances and services of the fuel
injector body shall be fulfilled by Bosch relevant service
stations or JAC designated service stations.