TIAGO

ELECTRICAL

8.11 GLOWPLUG CONTROL UNIT

Location:

The Glow Plug Interface Unit mounted on Crash

member Outer LH.

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 what

the command given by ECU is followed.