GF14.40-W-3003A | Component description for the pump module | 23.12.04 |
ENGINE 541.9 in MODELS 930, 932, 933, 934 with CODE (MS4) BlueTec 4
ENGINE 541.9 in MODELS 930, 932, 933, 934 with CODE (MS5) BlueTec 5
ENGINE 542.9 in MODELS 930, 932, 934 with CODE (MS4) BlueTec 4
ENGINE 542.9 in MODELS 930, 932, 934 with CODE (MS5) BlueTec 5
W14.40-1070-76
Location
Shown on engine 541.9
4 Pump module
The pump module (4) is located on the inside of the right frame side member at the height of the AdBlue tank.
Task
The pump module (4) suctions up AdBlue out of the AdBlue tank, filters it and pumps it to the metering device.
W14.40-1032-76
Design
1 Pressure filter
2 Line fitting AdBlue (feed)
3 Line fitting AdBlue (return)
4 Pneumatic shift valve
5 Connection (compressed air)
6 Pressure reservoir
7 Pressure filter and pressure reservoir housing
8 Line fittings coolant (outlet)
9 Pressure reservoir filling valve
10 Filling connection for pressure reservoir
11 Line fittings coolant (inlet)
12 Pump housing
13 Housing cover
14 Electrical connector
15 Cover venting membrane
16 Line fittings AdBlue (suction)
17 Suction filter (in intake fitting)
M25 SCR AdBlue pump
W14.40-1031-12
The pump module consists of a splash-proof plastic housing - the pump housing (12) and an aluminum block screwed on the inside - the pressure filter- and the pressure reservoir housing (7). The pump housing (12) contains the SCR AdBlue pump (M25), an electrical 3-chambered membrane pump.
Apart from the pressure filter (1) and pressure reservoir (6) the pressure filter and pressure reservoir housing also contains a pneumatic shift valve (4). It is also has connections for coolant lines and a duct for throughflow of coolant.
Function
If the SCR AdBlue pump (M25) receives the signal to switch on then its sucks AdBlue our of the AdBlue tank. The suction filter (17) with a mesh size of 100 μm integrated in the line fitting for AdBlue (16) prefilters the AdBlue.
The pump brings the AdBlue up to an operating pressure of about 6 bar and delivers it further into the pressure filter and pressure reservoir housing (7). The AdBlue passes through the pressure filter (2) inside the housing with a mesh size of 30 μm in order to remove the remaining fine dirt particles before it is pumped further in the direction of the metering device.
The pressure reservoir (6) is basically an accumulator bag filled with gas made out of rubber which has the task of compensating for pressure surges and to reduce the cut-in frequency of the SCR AdBlue pump (M25). It has a volume of about 0,13 liters. It is filled ex Works with nitrogen (N2). It can also be filled with oil and grease free air when refilling it.
Bleeding
The pneumatic shift valve (4) and the line fitting AdBlue (3) serve to achieve automatic venting of the pump module while operating or during initial startup. The pneumatic shift valve (4) is closed if it has compressed air applied to it.
The SCR AdBlue pump (M25) does not usually deliver "empty" since it switches if the fill level sensor in the AdBlue tank goes below a certain limit value. The pump can, however, run empty for a short time if the AdBlue in the tank "sloshes back and forth". However the engine control (MR) control unit recognizes the situation if the pump runs empty for longer than 10 seconds and automatic venting is initiated.
AdBlue depressurization
The AdBlue pressure inside the pump module and in the section of line between the pump module and the metering device is reduced after switching off the ignition to prevent frozen AdBlue from damaging the pump module, . The depressurization takes place via venting of the compressed air control unit. The pneumatic shift valve (4) is opened and this allows return flow of the AdBlue to the AdBlue tank.
Heating
A duct in the pressure filter and pressure reservoir housing (7) allows coolant to flow through it for heating and de-icing. The coolant feed is controlled by according to temperature by the MR control unit via a valve attached to the engine.