SsangYong Rodius (2013 year). Manual — part 88
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This is done periodically under certain operating conditions. When the resetting is finished, the new
minimum pulse value replaces the value obtained during the previous resetting. The first MDP value is
provided by the C3I. Each resetting then allows the closed loop of the MDP to be updated according to
the deviation of the injector.
B. Detection of leaks in the cylinders
The accelerometer is also used to detect any injector which may have stuck open. The detection
principle is based on monitoring the ratio. If there is a leak in the cylinder, the accumulated fuel self-
ignites as soon as the temperature and pressure conditions are favorable (high engine speed, high
load and small leak).
This combustion is set off at about 20 degrees before TDC and before main injection.
The ratio therefore increases considerably in the detection window. It is this increase which allows the
leaks to be detected. The threshold beyond which a fault is signaled is a percentage of the maximum
possible value of the ratio.
Because of the severity of the recovery process (engine shut-down), the etection must be extremely
robust.
An increase in the ratio can be the consequence of various causes:
Pilot injection too much
Main combustion offset
Fuel leak in the cylinder
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If the ratio becomes too high, the strategy initially restricts the pilot injection flow and retards the main
injection. If the ratio remains high despite these interventions, this shows that a real leak is present, a
fault is signaled and the engine is shut down.
C. Detection of an accelerometer fault
This strategy permits the detection of a fault in the sensor or in the wiring loom connecting the sensor
to the ECU.
It is based on detection of the combustion. When the engine is idling, the detection window is set too
low for the combustion caused by the main injection. If the ratio increases, this shows that the knock
sensor is working properly, but otherwise a fault is signaled to indicate a sensor failure. The recovery
modes associated with this fault consist of inhibition of the pilot injection and discharge through the
injectors.
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(8) Swirl control
A. Overview
Variable swirl valve
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The strong swirl caused by intake air is important element for anti-locking function in diesel engine. The
swirl control valve partially closes the intake port to generate the swirl according to the engine
conditions. When the engine load is in low or medium range, the swirl could not be generated because
the air flow is slow. To generate strong swirl, there are two passages in intake manifold, and one of
them has the valve to open and close the passage. When the valve closes the passage, the air flow
through the another passage will be faster, and the strong swirl will be generated by the internal
structure of the passage. This swirl makes the better mixture of air and fuel, eventually the combustion
efficiency in combustion chamber could be improved. This provides the enhanced fuel consumption,
power and EGR ratio.
Components
▶
HFM
Crankshaft position sensor
Variable swirl valve
Coolant temperature
sensor
Accekerator pedal
module
D20DTR ECU
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B. Input/Output for variable swirl valve
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C. Types of swirl
Swirl: One cylinder has two intake air ports, one is set horizontally and
the other one is set vertically. Swirl is the horizontal air flows in
cylinder due to the horizontal intake air ports.
Tumble: Tumble is the vertical air flows in cylinder due to the vertical
intake air port
Squish is the air flow at end of compression process according to the
design of piston head. In this DI engine, the squish is generated to
bowl type.
D. Swirl control
In DI type diesel engine, the liquefied fuel is injected into the cylinder directly. If the fuel is evenly
distributed in short period, the combustion efficiency could be improved. To get this, there should be
good air flow in cylinder. In general, there are two intake ports, swirl port and tangential port, in each
cylinder. The swirl port generates the horizontal flow and the tangential port generates the longitudinal
flow. In low/mid load range, the tabgential port is closed to increase the horizontal flow. Fast flow
decreases the PM during combustion and increases the EGR ratio by better combustion efficiency.
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