Engine cooling system thermal management, function

GF20.00-W-0003F

Engine cooling system thermal management, function

14.03.2019

Model	963
	with code M7T (Regulated coolant pump)
	with code V2B (Actros model generation 5)
Model	963
	with code M7T (Regulated coolant pump)
	with code V2F (Actros S/M cab, model generation 5)
Model	964
	with code M7T (Regulated coolant pump)
	with code V2J (Arocs model generation 5)
Model	964
	with code M7T (Regulated coolant pump)
	with code V3L (Actros BM964 model generation 5)

A2	Central gateway control unit (CGW)
A3	Drive control (CPC) control unit
A4	Engine management control unit (MCM)
A7	Advanced signal acquisition and actuation module (ASAM) control unit
A54	Lower radiator shutters controller unit
B640	Coolant pump rpm sensor
CAN 2	Interior CAN
CAN 3	Frame CAN
CAN 4	Drive train CAN
LIN 17	ASAM LIN 3
Y616	Fan clutch solenoid valve
Y616 b1	Fan rpm sensor
Y644	Switched water pump solenoid valve
Z4	Drive CAN bus star point
a	Coolant pump speed, signal
b	Coolant pump, actuation
c	Fan clutch fan speed, signal
d	Fan clutch, actuation
e	Coolant temperature, signal
f	Charge air temperature, signal
g	Engine speed, signal
h	Lower radiator shutters controller unit (A54), actuation (for code (M7K) Radiator shutters)
j	Lower radiator shutters controller unit (A54), status (for code (M7K) Radiator shutters)
l	Secondary coolant-retarder, status

W20.00-A001-76

General

The engine cooling heat management optimizes the efficiency of the engine and thus reduces fuel consumption. This is achieved by targeted and as-required actuation of the following components:

 Coolant pump

 Fan clutch

 Radiator shutters

As a result of the regulation of the coolant pump, the coolant flow rate is reduced by the engine to the necessary dimension in the respective operating status. In addition, the cool air flow rate of the radiator is controlled via the fan clutch depending on the operating status. In addition, the engine cooling heat management on vehicles with code M7K (Radiator shutters) includes cooling air control, which controls the aerodynamics of the vehicle depending on the coolant temperature.

The cooling air control is realized by actuating the lower radiator shutters controller unit (A54).

Regulation of electromagnetic coolant pump

The delivery rate of the electromagnetic coolant pump is continuously variable via the integrated electromagnetic viscous fan clutch. The electromagnetic viscous fan clutch is actuated by the engine management control unit (MCM) (A4) by means of a pulse width modulated signal. The engine management (MCM) control unit (A4) assesses the following information for this purpose:

 Coolant temperature

 Engine speed

 Engine throttle condition

 Compressor operating status (active/idle)

 Secondary coolant retarder operating status (with code B3H (secondary coolant-retarder))

Depending on the listed information, the engine management (MCM) control unit (A4) calculates the corresponding manipulated variable for the actuation of the viscous fan clutch.

 To achieve the max. braking effect of the secondary coolant-retarder in vehicles with code B3H (Secondary coolant-retarder), the coolant pump is actuated at full capacity in the secondary coolant-retarder braking mode.

Regulation of the magnetic clutch function

The delivery rate of the magnetic clutch is continuously variable via the integrated electromagnetic viscous fan clutch. The magnetic clutch is actuated by the engine management (MCM) (A4) control unit by means of a pulse width modulated signal.

The engine management (MCM) control unit (A4) assesses the following information for this purpose:

 Coolant temperature

 Engine oil temperature

 Charge air temperature

 Engine speed

 Fan speed

 Secondary coolant retarder operating status (with code B3H (secondary coolant-retarder))

Depending on the listed information, the engine management (MCM) control unit (A4) calculates the manipulated variable for the actuation of the magnetic clutch.

Cooling air control function (for code M7K (Radiator shutters))

The actuation of the lower radiator shutters controller unit (A54) is realized in a continuously variable manner by the advanced signal acquisition and actuation module (ASAM) control unit (ASAM) (A7) via the ASAM-LIN 3 (LIN 17). The radiator shutters are opened and closed depending on the following factors:

 Secondary coolant retarder operating status (for code B3H (secondary coolant-retarder))

 Engine brake operating status

 Air conditioning system operating status

 Heater capacity requirement

 Vehicle speed

 Outside temperature

 Coolant temperature

 Charge air temperature

 Engine speed

Depending on the listed information, the drive control (CPC) control unit (A3) uses a characteristics map to calculate the manipulated variables for actuating the radiator shutters.

 To prevent repeated shifting of the radiator shutters, a hysteresis is implemented between the opening and closing points.

This means that the minimum opening time of the radiator shutters is 0 s, even if the vehicle operating status resulted in the closure of the corresponding radiator shutters.

The lower radiator shutters controller unit (A54) closes and/or opens the slats as described in the following table:

Vehicle operating status	Radiator shutters
Ignition off, parking brake closed	Closed (step protection)
Engine running, parking brake opened	OPENED
Vehicle accelerating, speed 55 km/h	OPENED
Speed 55 km/h, no cooling requirement available	CLOSED
Speed falls below 55 km/h, cooling requirement available	Is opened and remains opened
Speed 20 km/h	OPENED
Air conditioning switched on	OPENED
Secondary coolant-retarder in braking mode (with code B3H (secondary coolant-retarder)); Coolant temperature < 94 °C and braking power <  150 kW	Opens 5 s after start of braking of secondary coolant-retarder
Secondary coolant-retarder in braking mode (with code B3H (secondary coolant-retarder)); Coolant temperature > 94 °C and braking power > 150 kW	Opens immediately
Coolant temperature > 97 °C	Opens immediately
Coolant temperature > 98 °C	OPENED
Charge air temperature > 8 °C above ambient temperature	OPENS
Charge air temperature > 10 °C above ambient temperature	OPENED

	Engine cooling system thermal management, overall network		GF20.00-W-0003-01F
	Engine management (MCM) control unit, component description	Only on vehicles with engine 470.9, 471.9, 473.9 A4	GF07.08-W-4110H
	Radiator shutters, component description	Only for vehicles with code M7K (Radiator shutters). A54	GF20.40-W-5010F
	Coolant pump component description	Only on vehicles with engine 470.9, 471.9, 473.9 B640, Y644	GF20.00-W-4000H
	Component description for the electromagnetic viscous coupling	Y616, Y616 b1	GF20.40-W-2002H
	Drive control (CPC) control unit, component description		GF30.35-W-4105H