Engine JAC HFC4DA1-2C. Manual - part 17

Maintenance manual for sunray hfc4da1-2c china-IV diesel engines

Section IX EGR System

The exhaust gas recirculation (EGR) introduces one small portion of exhaust gas from the exhaust pipe into the intake
pipe that is mixed with the fresh intake air to artificially increase the exhaust amount in the fresh intake air and thus
reduce the combustion temperature of engine and reduce the formation of NOx.

z The NOx is increased following the increasing of engine load and the EGR ratio shall increase accordingly.

z The EGR is not be performed when the engine coolant temperature is low;

z The EGR is not performed under idling or low load, as the NOx emission is not high in such case.

z The EGR is not performed under full load or acceleration;

z The water-cooled EGR further reduces the temperature of exhaust gas entering into the cylinder and further

reduces the emission of NOx.

Maintenance manual for sunray hfc4da1-2c china-IV diesel engines

Section X Exhaust System

The exhaust pipe is composed of four exhaust manifolds leading to the exhaust master pipe and one manifold leading
to the exhaust gas chamber of EGR valve. During the operation, the exhaust gas from the combustion chamber is
introduced into the EGR valve by the manifold leading to the exhaust gas chamber of EGR valve through the EGR
passage in the cylinder head. Under the control of the EGR valve, the exhaust gas is mixed with fresh air and enters
into the combustion chamber to realize exhaust gas recirculation and reduce the emission.

4DA1-2C diesel engine real-time monitors the pressure drop of the exhaust gas post-treatment unit to determine
whether the post-treatment system is working normally. Via two pressure ports on the sensor, the pressure on two
sides of the exhaust gas post-treatment unit is introduced. The sensor converts the measurement into voltage value and
feeds back to the control unit, which can guarantee the sufficient oxidization of grains and prevent the blockage of
catalytic converter.

Maintenance manual for sunray hfc4da1-2c china-IV diesel engines

Chapter III Working Principle of Engine Control and Actuator Units

Section I Overview of Diesel Common Rail System

The electronically controlled high pressure common rail system means one fuel supply mode in which the generation
of injection pressure and fuel injection are completely separated in the closed-loop system composed of high pressure
fuel pump, pressure sensor, and ECU. The high pressure fuel pump generates high pressure fuel and conveys to the
common rail pipe to realize precise control of fuel pressure within the common rail pipe. This fuel injection system
can ensure that the fuel injection pressure will not vary following the variation of the engine speed and thus relieve the
defect of traditional diesel engines. Instead of the common pulse theory, this system adopts the pressure-time
measuring theory and combines the high pressure common rail with the control of fuel injection solenoid valves of all
cylinders, in which the last pulse of the control unit introduces the injection signal into the solenoid valve to trigger
one injection cycle and the injection amount is controlled by the accumulated pressure and the open duration of the
injector. The injection pressure of EDC17 control system adopted by this engine is up to 1,600bar.

The electronically controlled common rail fuel injection technology of diesel engine integrates the computer control
technology, modern sensing and measuring technology, and advanced fuel injection mechanism. The main
characteristic of this technology is as below: The main parameters (including speed, torque, power, oil temperature, oil
pressure, water temperature, and turbocharger pressure of the diesel engine) under actual working conditions of the
diesel engine are measured by modern sensing and measuring technology and transmitted to the ECU and the ECU
compares these measurements with the pre-inputted optimized running MAPs of the diesel engine and processes and
calculates out the best values to control the pressure of common rail pipe and the open moment, duration, and
injection frequency of the high speed solenoid valves of the fuel injectors, in order to realize the best working state of
the diesel engine. The electric pulses generated by the ECU trigger the solenoid valves of the fuel injector as per
specified sequence to determine the open and close moments of each fuel injection cycle of the engine and flexibly
control the fuel injection speed and frequency. The common rail fuel injection mechanism forms directly or indirectly
constant high pressure fuel and distributes to each fuel injector. The electronically controlled common rail fuel
injection technology of the diesel engine can guarantee that the diesel engine achieves the best air-combustion ratio
and excellent atomization.

Diesel common rail injection system

High pressure

pump

Cut-off valve

(optional)

Fuel pressure sensor

Distribution

pipe

Fuel-water

Fuel tank

High pressure

Low pressure

Pressure

regulation valve

Fuel temperature

sensor

Fuel delivery pump

Other sensors

Accelerator
pedal

Fuel injector

Crankshaft
position
sensor

Camshaft position
sensor

Maintenance manual for sunray hfc4da1-2c china-IV diesel engines

The high pressure common rail system is composed of fuel tank, diesel filter, high pressure fuel pump, common rail
pipe, electronically controlled fuel injector, high pressure fuel pipe, and low pressure fuel return pipeline.

z It adopts direct injection combustion chamber system and common rail fuel supply system to realize high

performance, clean emission, low noise, and low vibration;

z Single camshaft and four-valve technology brings about higher air charging efficiency and improves the

combustion;

z High power per liter design and compact design;

z Variable nozzle turbocharger (VNT) control;

z Exhaust Gas Recirculation (EGR);

z Electronic throttle control.

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