A high pressure and high temperature are produced in the
combustion chamber during the compression phase. This has a major
impact on the combustion process. The heat dissipa-tion is low as a
result of the small surface area of the combustion chamber.
Preglowing is only necessary at low temperatures.A basic
distinction is made between three glow phases:
Preglow period Glow period Afterglow period
Controlling the systemThe glow plug system is controlled by the
electronic control unit. Preglowing is activated only if the
coolant temperature is below +10 C.The preglow period is all the
longer, the colder the coolant.
Preglowing is followed by a glow period of 5 seconds.
Afterglowing is activated at coolant temperatures below +20 C
when the engine is started for a period of about 30 seconds. In
total, an afterglow period of 90 seconds is possible, depen-ding on
the coolant temperature. Afterglowing is switched off once engine
speed is greater than 2500 rpm.
