ZEST/BOLT

ELECTRICAL

12.13

GLOWPLUG CONTROL UNIT

OPERATIONAL DESCRIPTION

The aim of Glow Plug control Unit (GCU) 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 GCU 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 control unit

must allow the EMS to operate in all of above

conditions with possibility to choose the driving

method & parameter optimization.

Pin Description:

Pin 30:

Direct battery supply.

G1 :

Power signal for glow plug no.1

G2 :

Power signal for glow plug no.2

G3 :

Power signal for glow plug no.3

: Power signal for glow plug no.4

Pin 86:

Power supply via main relay

ST :

Command signal from ECU to glow plug

controller.

DI :

Diagnostic feedback signal from glow plug

controller to ECU.

Pin 31:

GND