Thermo Top Evo 2 General description
203
2.2.1 Glow plug/Flame monitor
The glow plug/flame monitor is connected to the control
unit (SG) via an electrical line with a connector (B9). The
glow plug is fastened to the evaporator mount with a
retaining spring (B2). A cooling flag (B3) provides for heat
dissipation from the glow plug, and therefore reduces the
temperature at the glow-plug connection lines.
The glow plug ignites the fuel-air mixture in the start-up
phase and is switched off after the "full load" state is
reached. From this point it is used exclusively for flame mon-
itoring. If the flame extinguishes, the electrical resistance in
the glow plug drops as the result of the missing heat appli-
cation. This is detected in the control unit.
2.3 Heat exchanger
The heat generated in the heat exchanger by combustion is
transferred to the coolant circuit.
2.3.1 Temperature sensor and overheating sensor
The temperature sensor detects the coolant temperature in
the heat exchanger of the heater as an electrical resistance.
This signal is fed to the control unit, where it is processed.
The temperature sensor (W5) and the overheating sensor
(W6) for a unit together with the cable and the connector.
The overheating sensor protects the heater against imper-
missibly high operating temperatures. This reacts at a tem-
perature above 125 °C and switches off the heater.
2.4 Circulating pump
The U4847 Econ circulating pump ensures a feed rate of the
coolant in the vehicle heater and heater circuit.The pump is
switched on with the control unit and runs during the entire
operation of the heater. The circulating pump is a centrifu-
gal pump with a brushless EC motor.
The circulating pump is equipped with a 2-pin connector
output and is connected to the control unit (SG) by means
of a separate wiring harness.
2.5 Metering pump
The fuel metering pump is a combined pumping, metering
and shut-off system. This dry-primeable reciprocating piston
pump pumps the fuel from the vehicle fuel tank to the fuel
connection piece of the heater via fuel lines. Installation is
usually carried out near the fuel tank. The metering pump
contains no pulsation damper and is equally well-suited for
diesel and petrol. The metering pump is connected to the
control unit via the heater-unit wiring harness and to an
earthing point on the vehicle body.
Fig. 204 Heat exchanger
W2 W5 W4 W3
W6
W1
W1 = Heat exchanger
W2 = Cable of temperature sensors
W3 = Ejomat DG 40x10 self-tapping screw
W4 = Retaining spring for sensors
W5 = Temperature sensor
W6 = Overheating sensor
Fig. 205 U4847 Econ circulating pump
To Next Page
Loading...
Need help?
General
