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ELECTRICAL
52
11 GLOWPLUG CONTROL UNIT
LOCATION
The Glow Plug Interface Unit mounted on water
channel RHD
OPERATIONAL DESCRIPTION
The aim of Glow Plug Interface Unit (GPIU) is to
achieve high degree of flexibility in driving the glow
plugs that are included in a standard EMS system
for diesel engines. It is evident that the requirement
for GPIU depends from the driving characteristics
required by the glow plugs.
In a modern direct injection diesel engine the
function developed by glow plug may be
summarized as follows:
Auxiliary starting device
Cold diesel engines due to high levels of internal
frictions & thermal losses are reluctant to start.
Often need of auxiliary devices like glow plugs are
the only method to guarantee engine start. The
glow plug power dissipation increases the
combustion chamber temperature allowing the air
fuel mixture to reach its self-ignition condition.
Auxiliary combustion control device
The air fuel mixture self-ignition points are mainly
influenced by two factors: pressure & temperature
inside the combustion chamber. The temperature
control in all those condition in which the
combustion chamber is relatively “cold” (i.e. during
cut-off or during post-start) may improve the
reduction of ignition delay with large benefit in
terms of emission & combustion efficiency.
Auxiliary Power Management device
The total power dissipation of glow plug is not
negligible (it may vary from 240W to 750W
according with glow plug characteristics). In some
cases, it may be useful to increase the engine load
operating point in order to achieve higher exhaust
temperature (e.g. in order to start the regeneration
of diesel particulate filter). The glow plug activation
in this condition may help either directly, increasing
combustion temperature indirectly increasing
engine load as required.
The features of modern Glow plug Interface unit
must allow the EMS to operate in all of above
conditions with possibility to choose the driving
method & parameter optimization.
Command & feedback Signal Description
Command signal
The glow plugs are supplied by control unit with
battery voltage (12V). The glow plug temperature
is controlled by ECU through a function stored in
memory, which links glow plug temperature with the
duration of heat signal (12V).
Feedback Signal
Feedback signal given by glow plug controller to
EMS ECU. Glow plug informs the EMS ECU
whether the command given by ECU is followed.
Circuit Diagram