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DAF XF105. Manual - part 102

200528

3-27

Control functions

DMCI ENGINE MANAGEMENT SYSTEM

XF105 series

3.13 ENGINE PROTECTION FUNCTIONS

The general task of this function is to limit the

requested quantity of fuel, related to the engine

speed, atmospheric pressure, coolant

temperature and other engine/vehicle conditions.

The controls ensure that the engine and drive

train are not mechanically and/or thermally

overloaded. The engine torque is limited or

reduced for this purpose. The protection

functions can be sub-divided into two groups:

Thermal engine protection

Mechanical engine protection

Thermal engine protection
1.

Cooling problem detection

Over-heating protection

Exhaust gas temperature limitation

Mechanical engine protection:
1.

Turbocharger protection

Height correction

PTO/engine speed control torque limiting

Fuel temperature correction

Engine oil pressure protection

Engine speed protection when engine is cold

Excess engine speed detection

i401009

D965

1 2

high-side

low-side

Cyl.6

B136

1 2

high-side

low-side

Cyl.5

B135

1 2

high-side

low-side

Cyl.4

B134

1 2

high-side

low-side

Cyl.3

B133

1 2

high-side

low-side

Cyl.2

B132

A12

A23

A24

A15

A19

A16

A11

A20

1 2

high-side

low-side

Cyl.1

Pump units

B131

1 2

high-side

low-side

Cyl.6

B426

1 2

high-side

low-side

Cyl.5

B425

1 2

high-side

low-side

Cyl.4

B424

1 2

high-side

low-side

Cyl.3

B423

1 2

high-side

low-side

Cyl.2

B422

1 2

high-side

low-side

Cyl.1

Injectors

B421

pres.

F744

2 1

signal

ground

oil

temp.

oil

temp.

F649

2 1

signal

ground

3 4

supply 5V

signal

shield

inlet

pres.

boost

pres.

F713

1 2

signal

ground

fuel

temp.

fuel

5 1

supply 5V

signal

speed

fan

ground

signal

F566

F743

temp.

coolant

temp.

second

B335

oct.

fan

ground

signal

C16

C31

C36

C35

supply

C60

C61

C62

Vehicle

CAN2

low

Vehicle
CAN2
high

2 1

signal

return

F552

speed

crankshaft

A22

A21

A14

A18

A13

A10

A17

C26

A34

A46

C25

A45

A41

C34

A42

C30

C29

C33

A38

A37

A27

A28

A30

A49

A50

A60

CAN2 low

CAN2 high

B53

B45

Vehicle

CAN1

low

Vehicle
CAN1
high

CAN1 low

CAN1 high

B35

B27

DMCI ENGINE MANAGEMENT SYSTEM

3-28

200528

Control functions

XF105 series

Thermal engine protection
1. Cooling problem detection
The aim is to prevent over-heating due, for

example, to a non-functioning coolant pump

because of a broken poly-V-belt or a blockage or

leak somewhere in the cooling system. This

detection is active when the engine has been

running for a certain time, the engine speed is

higher than a certain value and the measured

temperature from both temperature sensors

(F566 and F743) is higher than a certain value.

There are three ways in which a cooling problem

can be detected:

When the temperature difference between

the two temperature sensors (F566 and

F743) is higher than a certain value (F566 is

located at cylinder 1 and F743 is located at

cylinder 6). Too great a difference in

temperature between cylinders 1 and 6 could

mean that the coolant pump is not

functioning properly.

When the signal from the second coolant

temperature sensor (F743) rises too much

within a certain time. A rapid rise on coolant

temperature at cylinder 6 could mean that

the coolant pump is not functioning correctly.

When no engine speed signal is received

from the electronically-controlled fan clutch

(B335). This could mean that the Poly-V belt

is broken and that therefore the coolant

pump is no longer operating.

If DMCI has recognised the cooling problem then

the injected fuel will be limited so that the engine

will be able to supply less torque. The yellow

engine warning will also be activated.

Relevant components

Coolant temperature sensor (F566)

Second coolant temperature sensor (F743)

Electronically-controlled fan clutch (B335)

Crankshaft sensor (F552)

Pump units (B131 to B136)

Injectors (B421 to B426)

2. Over-heating protection
If the coolant temperature (F566) exceeds a

specific maximum value, the maximum quantity

of fuel to be injected is reduced. Heat

development will be less as less energy is put into

the engine.

Relevant components

Coolant temperature sensor (F566)

Pump units (B131 to B136)

Injectors (B421 to B426)

200528

3-29

Control functions

DMCI ENGINE MANAGEMENT SYSTEM

XF105 series

3. Exhaust gas temperature limitation
The objective is to limit the exhaust gas

temperature by limiting the maximum quantity of

fuel to be injected and therefore to protect the

turbine of the turbo against over-heating. This

limit is a calculation of the exhaust manifold

temperature, the maximum permissible exhaust

gas temperature and the air flow trough the

engine. This function is active above a certain

engine speed and account is taken of the

warming up of the turbo housing.

Relevant components

Charge boost pressure and temperature

sensor (F649)

Crankshaft sensor (F552)

Mechanical engine protection
1. Turbocharger protection
a. Protection against too high a boost pressure

To protect the turbocharger against overrevving

and to protect the engine against excessive

mechanical loads, the torque is reduced if the

boost pressure of the engine becomes (much)

too high. The electronic unit uses engine speed

(F552) and charge boost pressure (F649) signals

to calculate whether the compressor speed and/

or the engine load is likely to become too high.

Too high a speed of the turbocharger at a specific

engine speed (for instance when the waste gate

of the turbocharger is not functioning) may cause

an excessive boost pressure. If the turbocharger

speed becomes too high, the compressor wheel

will deform too much and lubrication of the shaft

will be inadequate; this may cause damage. To

prevent this, less fuel is injected at this point and

consequently the exhaust gas flow is reduced.

The turbocharger speed will automatically

become lower.

Relevant components

Crankshaft sensor (F552)

Charge boost pressure and temperature

sensor (F649)

Pump units (B131 to B136)

Injectors (B421 to B426)

DMCI ENGINE MANAGEMENT SYSTEM

3-30

200528

Control functions

XF105 series

b. Protection against too high a temperature

To protect the turbocharger against excessive

exhaust gas temperatures, the injected quantity

of fuel is reduced when the temperature of the

exhaust gas becomes too high. The exhaust gas

temperature is calculated by the electronic unit; it

is not measured by a sensor. The electronic unit

uses the engine speed (F552), charge boost

pressure and charge temperature (F649) to make

this calculation.

Relevant components

Crankshaft sensor (F552)

Charge boost pressure and temperature

sensor (F649)

Pump units (B131 to B136)

Injectors (B421 to B426)

2. Height correction
Depending on the height (low atmospheric

pressure), a maximum quantity of fuel to be

injected is calculated. A decrease in the "quantity

of air supplied" by the turbocharger as the vehicle

is driven at a specific height may result in high

exhaust gas temperatures. If the air is thinner, the

quantity of fuel to be injected is adjusted, i.e.

reduced, accordingly.

Relevant components

Crankshaft sensor (F552)

Internal atmospheric pressure sensor

Pump units (B131 to B136)

Injectors (B421 to B426)

3. PTO/engine speed control torque limiting
During the various engine speed control functions

via the steering column switch and the application

connector ("nvar", "n2", "n3"), the quantity of

injected fuel can limited to protect against

overload of any PTO-driven components. This is

a torque limiting function where the limiting

percentage can be programmed with the aid of

DAVIE XD. See also the control function "Engine

speed control" and the document "Test and

customer parameter information DAVIE XD".

Relevant components

Crankshaft sensor (F552)

PTO torque limiting active (software -

customer parameters)

Pump units (B131 to B136)

Injectors (B421 to B426)

Content .. 100 101 102 103 ..