The fuel pressure generated by the vane cell pump in the discharge side depends on the rotational speed of the pump.
9
To limit the pressure, there is a pressure control valve right next to the vane cell fuel pump and connected to the discharge side.
9
The pretensioning of the pressure spring determines the opening pressure.
9
2.3.2
High-pressure Part
10
HOCHDRUCK.BMP
10
The radial plunger high-pressure pump produces the pressure (approx. 1000 bar) needed for injection. It is powered by the drive shaft.
11
2.3.3
Fuel Distribution with Distributor
RUECKD.CDR
12
18
2.3.4
Injection Actuator
19
2.3.5
Angle of Rotation Sensor
22
2.4
Pump Control Unit
24
2.4.1
Purpose
24
2.4.2
Pinning
25
2.5
Engine Control Unit
26
2.5.1
General
26
2.5.2
Engine Control Unit Connectors
29
2.5.3
Cable Harness Connectors
29
2.5.4
Pin Configuration
29
2.5.5
Pinning of Engine Control Unit
30
A67_03 EDC MS 6_4.doc
3.1
A67_03 EDC MS 6_4
2.6
Page 2 of 10
Needle Travel Sensor
Connector pinning
32
NBF.CDR
32
The internal resistance of the needle travel sensor is 65 – 160 .
32
2.7
Engine Speed Sensor
33
Circuit schematic
33
Connector pinning
33
2.8
Cooling Water Temperature Sensor
2.8.1
2.9
Measured Figures
Charge Air Pressure Sensor
LDF.BMP 2.9.1
2.10
2.11
34 34
35
35 Technical Data
Pedal Value Sensor
Circuit schematic Proximity Switch
35
35
36 37
2.11.1
Proximity Switch Installation
38
2.11.2
Proximity Switch Settings
38
2.12
Steering Column Control
39
2.12.1
Circuit Schematic
40
2.12.2
Operation (Combined Steering Column Switch)
41
2.12.3
Change Idling Speed
42
2.12.4
Intermediate Speed Control (ZDR)
43
2.13 2.13.1
2.14 2.14.1
3.2
32
FGB/FGR Switch Circuit Schematic and Pinning
Resistor Bank Pinning
49 49
50 50
A67_03 EDC MS 6_4.doc
A67_03 EDC MS 6_4
Page 3 of 10
System Description EDC MS 6.4 (VP 44) 2.1 General Needle travel sensor Charge air pressure
Engine speed
Watertemperature.
Y
R
O M
E
M
S U
Steering Column
A
switch T E S
FGB/FGR switch
Terminal 30
Terminal 15 Brake Speed
Engine
PWM
Clutch
control unit
ISO diagnosis
Warning lamp Pedal value
i s s o n g i D a
t s e
Exhaust brake
u q r e CAN bus
Exhaust brake Pump control unit
A67_03 EDC MS 6_4.doc
3.3
A67_03 EDC MS 6_4
Page 4 of 10
The EDC version MS 6.4 with radial plunger distributor injection pump VP 44 is used in the D0834 (4-cylinder) and D0836 (6-cylinder) engines. This diesel injection system requires an engine control unit and a pump control unit for electronic regulation. This split role is necessary to prevent overheating of electronic components on the one hand, and to guard against interference caused by the in part very high currents (up to 20 A) in the injection pump.
The pump control unit detects internal sensor signals like angle of rotation a nd fuel temperature and evaluates them for matching injection timing. While the engine control unit processes all engine and environmental data picked up by external sensors and is then able to compute how the pump should be controlled.
The engine and pump control units exchange data on the CAN bus.
3.4
A67_03 EDC MS 6_4.doc
A67_03 EDC MS 6_4
Page 5 of 10
A 6 7 _ 0 3 E D C M
2 . Pump control unit
S 6 _ .d o c
Angle of rotation sensor
Vane cell fuel pump
e s
S y s
n
m e s c ri ti n
ri u r I c i n u m p
Radial plunger high-pressure pump with distributor shaft and outlet valve (pressurevalve)
I njection actuator and injection actuator
High-pressure solenoid valve with valve needle
Solenoid valve (timing valve)
3 .5
A67_03 EDC MS 6_4
Page 6 of 10
2.3 Schematic of Fuel Supply Injectionnozzles
Leakage oil tube d = 4 Flame glow p = 1 bar d = 4 mm
p=p
min
-0.2 bar d=7 mm
Solenoid
p=2.5 bar d=7 mm
Leakage oil from Prefeeder pump
To solenoid valve
Overflow
Intake
p = 2.5-3 bar M 10 x 1 Prefilter
M 12 x 1.5
-0.2 to +0.3 bar
From tank Control unit schematic Source 51.12000.8019
To tank
Fuel supply
A mechanical gear pump, the prefeeder, draws fuel from the tank through the prefilter and the filter(s) to the control unit. The lead pressure is > 2.5 bar. The control unit is set up on the distributor injection pump. It includes a pressure regulator that reduces the lead pressure to
+
0.2 bar so that the fuel enters the
distributor injection pump unpressurized. The overflow valve for fuel return is also part of the control unit.
3.6
A67_03 EDC MS 6_4.doc
A67_03 EDC MS 6_4
Page 7 of 10
2.3.1 Low-pressure Part
Overflow throttle valve
Pressure valve
Vane cell fuel pump [turned 90
o
for clearer
presentation]
The low-pressure part produces sufficient fuel for the high-pressure part. More fuel is fed than is required for injection. The excess fuel flowing back to the tank cools the injection pump and removes bubbles of air.
A67_03 EDC MS 6_4.doc
3.7
A67_03 EDC MS 6_4
Page 8 of 10
2.3.1.1 Vane Cell Fuel Pump
Discharge side
Drive shaft
Cell Flywheel
Inlet side
Vane
The radial plunger distributor injection pump incorporates the vane cell pump for feeding the fuel. The flywheel powered by the drive shaft is held in a ring. This flywheel bears the vanes, which are pressed outwards against the ring by the centrifugal force. The fuel entering the case without lead pressure by way of the inlet is transported to the discharge side by the turning of the flywheel.
3.8
A67_03 EDC MS 6_4.doc
A67_03 EDC MS 6_4
Page 9 of 10
2.3.1.2 Pressure Control Valve
The fuel pressure generated by the vane cell pump in the discharge side depends on the rotational speed of the pump. To limit the pressure, there is a pressure control valve right next to the vane cell fuel pump and Pressure spring
connected to the discharge side. Valve piston
The pretensioning of the pressure spring To inlet side
determines the opening pressure. Hole
From discharge side
2.3.1.3 Overflow Throttle Valve
To cool and ventilate the distributor injection pump, fuel flows through the overflow throttle valve and back to the fuel tank. Pressurespring
The spring-loaded ball valve opens at a preset pressure.
Ball valve
In the side channel to the ball valve there is a throttle To overflow
hole of very small diameter. This throttled link simplifies automatic ventilation of the pump. The total low-pressure circuit of the Throttle hole
pump is attuned so that a small amount of fuel is always able to flow back to the fuel tank by way of the pump overflow.
A67_03 EDC MS 6_4.doc
3.9
A67_03 EDC MS 6_4
Page 10 of 10
2.3.2 H igh-pressure Part
Distributor
Radial plunger high-pressure pump [turned 90
High-pressure
o
solenoid valve
Snubber valve
HOCHDRUCK.BMP
The high-pressure part is responsible for generating high pressure, distributing fuel and metering fuel together with control of port closing.
