GF15.20-P-4020P Component Description For Glow Plugs

GF15.20-P-4020P Component Description For Glow Plugs
ENGINE 642 in MODEL 164.1 /8, 203.0 /2, 221.0 /1, 251.0 /1 up to Model Year 2008 /AEJ 07
ENGINE 642 in MODEL 209.3 /4
ENGINE 642.920 in MODEL 211.022
- except CODE (494) USA version
ENGINE 642.920 in MODEL 211.022 /222
- except CODE (498) Japan version
ENGINE 642.921 in MODEL 211.084 /089 /284 /289
ENGINE 642.920 in MODEL 211.020 /220 /620, 219.322
ENGINE 642i n MODEL 461.3, 463.3 up to 31.5.12





R9 Glow plugs

Location
The glow plugs are screwed on under the rail on the left and right in the cylinder heads.

Task
The glow plugs warm the combustion chamber in order to reach and secure the required ignition temperature of the fuel-air mixture under all operating conditions.





Body
50 Plug connector
51 Socket
52 O-ring
53 Plug housing
54 Heater body seal
55 Glow tube
56 Sensor coil
57 Heating coil

The glow plugs consist of a heater tube which is pressed firmly and gas-tight into the plug housing. The heater tube consists of a hot gas and corrosion-resistant pipe which carries on the inside a glow coil embedded in compressed magnesium oxide powder. The glow coil consists of 2 series resistors.
These are:
^ The sensor coil
^ The heating coil

The sensor coil housed in the tip of the glow pipe consists of a material with a positive temperature coefficient. The heating coil consists of a virtually temperature-independent resistance.
The heating coil is welded for contacting at the ground end in the round end of the glow tube. The sensor coil is contacted at a plug connector over which connection is made to the on-board electrical





Function
Application of the voltage to the glow plugs initially causes the majority of the electrical energy to be converted into heat in the heating coil. The temperature of the plug tip increases steeply. The temperature of the sensor coil also increases after some delay and thus also the resistance. The power consumption and thus the overall performance of the glow plugs come close to the balanced condition.