Nissan Qashqai J11. Manual - part 469

SYSTEM

EC9-31

< SYSTEM DESCRIPTION >

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Coolant heaters or air heaters

The air heater is activated on a driver request.
The thermoplunger are exclusively used to increase engine load during DPF (Diesel Particulate Filter) regen-
eration. When the vehicle is in a regenerating phase and the load is low,  the coolant heaters are activated to
increase the overall load.

ENGINE TORQUE LOSSES

The torque losses are the sum of three components: the rubbing, the pumping, and the torque losses caused
by accessories consumption.
• The basic friction torque loss uses the coolant liquid temperature sensor and the engine speed for the torque

correction.

• Accessories

′

 consumption is caused by additional electrical (alternator power) and mechanical (power steer-

ing and air conditioning) components.

MINIMUM AVAILABLE TORQUE

The minimum available torque is used for the minimum driver setpoint calculation and the intersystem informa-
tion.
The minimum torque is designed with a hyperbolic shape depending on the difference between the engine
speed and the idle speed set-point:
• When the engine speed is under the idle speed set-point, the minimum torque is equal to the hyperbolic

torque which increases to avoid an engine stalling.

• When the engine speed is over an engine speed threshold, the minimum torque reaches the engine torque

losses with a ramp.

When the engine starts, a specific torque set-point is calculated to ensure the engine start. This torque is
dependent of the engine speed and the coolant temperature.
At first, a calculation of the starting torque value is performed. In case of a difficult start (too long), this torque
may be increased thanks to ramp.
The start torque offset is progressively set to zero to ensure a transition with the current torque set-point.

MAXIMUM AVAILABLE TORQUE

The maximum available torque results of a minimum selection including all powertrain constraints:
• Transmission torque limitation
• Maximum engine torque
• Torque reduction for the heating protection
• Torque for smoke limitation
• Fail-safe

Transmission torque limitation

This limitation is the maximum torque to protect the transmission from a mechanical overload:
• For a manual transmission, the limitation value of the torque is function of the engine speed and the trans-

mission ratio.

• For an automatic transmission, the limitation value is directly supplied by the automatic transmission.

Maximum engine torque

The maximum torque depends on the engine speed and the manifold air pressure. It is corrected by:
• The soot mass value in order to take into account the limitations due to the particulate filter
• The atmospeeric pressure
• The upstream inlet throttle temperature.
The maximum engine also depends on the combustion mode (the normal or the regeneration combustion
mode). In some conditions (DPF clogging, etc.), this maximum available torque is reduced in order to keep the
engine within its safety working limits.

Torque for the heating protection

This torque limitation is dedicated to the protection of the engine from an overheating. This limitation calcula-
tion depends on the engine speed, the engine coolant temperature, the intake air temperature and the vehicle
speed.

Torque for the smoke limitation

This torque limitation is used to reduce the smoke emissions during a high torque driver request. The maxi-
mum fuel mass that can be injected is limited according to the maximum richness depending on the gear ratio,
the engine speed, and the intake air mass flow. This value is corrected depending on the vehicle speed and
the coolant temperature.

Fail-safe

EC9-32

< SYSTEM DESCRIPTION >

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SYSTEM

The ECM limits a engine torque in case of malfunction of engine component or ECM.
Depending on the engine components, ECM activates the fail-safe mode of the torque limitation level 1 (low
limitation), the level 2 (mean limitation), or the level 3 (strong limitation function of vehicle speed).

FAST SET-POINTS TO COMPLETE TORQUE REQUEST

For each combustion mode (the normal combustion mode, the regeneration combustion mode, and the pro-
tection combustion mode), a torque model is designed to calculate the total fuel mass quantity, the estimated
mean effective torque, the combustion efficiency and the current fuel consumption for the final torque set-point
and the engine current speed.
The total fuel mass quantity is corrected to take into account the main injection advance deviation and the
mass air flow deviation.
For each combustion mode, the after and the post injection relative efficiencies are calculated to determine the
fuel mass quantity needed to perform the engine inner torque.
The after injection relative efficiency is equal to one in normal combustion mode and to zero in a regeneration
combustion mode or in a protection combustion mode.
The post injection relative efficiency is function of the post injection timing and the difference between the cur-
rent and the basic post injection timing.

FINAL TORQUE REQUESTS SETTING

The final torque requests are computed by the arbitration with the driver request, the intersystem torque
request (VDC/ESP), the torque limitations and the curative anti-jerk correction.
The set-point torque is used for fuel mass calculation. It is filtered by the preventive anti-jerk and corrected by
the curative anti-jerk.

COMBUSTION CONTROL

COMBUSTION CONTROL : System Description

INFOID:0000000010438173

SYSTEM DESCRIPTION

The torque set-point is converted into a total fuel quantity injected. This quantity is split in various injections
according to a mapped injection pattern. Thus, a fuel quantity and an initial phasing of injection are allocated
for each injection. The choice of the number of injection (limited to five maximum) is given with different con-
straints such as acoustic, performance and emissions.
In the DPF (Diesel Particulate Filter) regeneration phase, post injections do not contribute to the torque elabo-
ration but to the increase of the DPF temperature. Therefore, the fuel consumption increases in the DPF
regeneration phase.

FUEL SUPPLY AND PRESSURE CONTROL SYSTEM

Fuel Supply System

The fuel supply system consists of two circuits: the fuel low and high-pressure circuit.
The fuel low-pressure circuit brings fuel from the tank to the high-pressure fuel pump through the fuel filter
(with fuel heater).
The high-pressure circuit function is to put the fuel under pressure and distribute it to the injectors:
• High-pressure fuel pump
• Fuel flow actuator
• Common rail
• Fuel injectors
The low-pressure fuel (coming from low-pressure circuit) is transferred to the high-pressure pump part via the
fuel flow actuator, which regulates the fuel flow quantity. The high-pressure fuel pump consists of a three-pis-
ton pump.
The fuel under pressure goes to the common rail, which distributes the fuel equally to each injector.
Finally, the commanded injectors deliver the fuel flow entering the cylinder.

Fuel Pressure Control

The combustion quality is influenced by the size of the droplets sprayed into the cylinder. In the combustion
chamber, smaller fuel droplets will have enough time to burn completely and will produce less smoke and less
unburnt particulate matter. To meet pollution requirements, the size of the droplets needs to be reduced and
hence so too do the injection orifices.
Since these orifices are smaller, less fuel can be injected for a given pressure, which in turn limits the power.
To counter this drawback, it is necessary to increase the quantity of injected fuel, which involves raising the
pressure (and the number of orifices on the injector nozzles). The pressure is continuously regulated to high

SYSTEM

EC9-33

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pressure in the rail. The measurement circuit consists of an pressure sensor on the rail and transmits the pres-
sure signal to ECM.
The high-pressure pump is self-supplied by an integrated gear pump. This supplies the rail, whose pressure is
controlled for loading by the fuel flow actuator. The flow regulation actuator allows the high-pressure fuel pump
to supply only the necessary quantity of diesel for maintaining pressure in the rail.
Pressure regulation can be done with one actuator in case of magnetic injectors because of their natural leak
during injector closing.

INJECTION CONTROL

The injection control parameters are the quantities to inject and their respective advances. The system per-
forms one to five injections.
The injectors are magnetic injectors. An electrical current (pulse) is sent to each injector holder based on the
previously computed data.
To control injector, ECM punctually drivers energy to obtain actuator deformation and the injector opening.
During the injection time, the length of electrical pulse is computed with the fuel flow demand and injectors cor-
rections. The system has three injector corrections:
• Injector adjustment value registration
• Zero fuel calibration
• Pressure wave correction

Injector Adjustment Value Registration

Injector adjustment value indicates manufacturing tolerance. The injector adjustment value which is correctly
stored in ECM is needed for precise fuel injection control. A performance of emission control and a driveability
may effect when there is a mismatch between the following two values.
• The injector adjustment value stored in ECM
• The injector adjustment value of the injector which is installed on the vehicle

Zero Fuel Calibration (ZFC)

During the lifetime of an injector, it is subject to thermal and mechanical constraints that modify the injection
characteristics. This wear-and-tear on the orifices (blocked or expanded holes) causes drift in the quantity of
injected fuel, which can lead to smoke generation or increased noise. To compensate for this drift, ECM imple-
ments a teach-in in the raised foot phase and under certain condition, which allows it to regulate the ZFC cor-
rector parameter.

Pressure Wave Correction:

The first injection causes a pressure wave in the pipe between rail and injector and the bores in the injector
itself. The quantity of the next injections is influenced by this pressure wave.
Main parameters of this influence are:
• Rail pressure
• Distance between the two injections
• Fuel temperature
• Injection quantities of both injections
The pressure wave correction minimizes the influence of the first injection on the next injections with simple
structure and parameters which can be measured.

TEMPERATURE BEFORE TURBINE CONTROL

Upstream turbine temperature control sequentially uses injection parameters:
• Main injection phasing
• Post injection fuel mass
• Total fuel mass quantity
• Maximum torque
In normal combustion mode (without regeneration), the regulation aims to protect the turbine. If the tempera-
ture exceeds the recommended limits, the regulation is able to limit total fuel mass quantity and torque
demand.
In regeneration mode, to increase the temperature in exhaust line, the regulation controls main injection phas-
ing and post injection.
The purpose is to obtain the highest temperature while respecting the recommended limits. In addition, the
regulation protects the turbine when the temperature is too hot.

WATER IN FUEL FUNCTION

The water in fuel detection sensor is an optional sensor integrated in the fuel filter. This function prevents seri-
ous damages on the common-rail system caused by water presence.

AFTER TREATMENT SYSTEM

EC9-34

< SYSTEM DESCRIPTION >

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SYSTEM

AFTER TREATMENT SYSTEM : System Description

INFOID:0000000010308986

DESCRIPTION

This system has two main functions:
• Use the present oxygen in exhaust gases to transform the CO in CO2, and the HC in CO2 and H2O.
• Increase the temperature of exhaust gases (with the exothermal energy of the oxidation reaction) to allow

the regeneration in the DPF (Diesel Particulate Filter).

To be effective, the catalytic converter must reach the working temperature of 350 to 400

°

C (662 to 752

°

F).

NOX TRAP

On diesel engines, it is possible to reduce the NOx produced by the engine by inserting a NOx-trap into the
exhaust line. This system works by alternating phase of load and phases of purges.
There are two types of purge, depending on the pollutant type:
• NOx purge
• SOx purge
These purges are made of alternative rich and lean phases, so in order to control them a O2 downstream pro-
portional sensor is added to the system.
The management of these requests has to manage the compromise between:
• Improve the NOx emission (objective leading to increase the number of purges)
• Do not impact on the customer on the fuel consumption and of the oil change interval (objective leading to

decrease the number of purges)

DPF (DIESEL PARTICULATE FILTER)

The DPF filters up to 99% of the soot particulates that have not been filtered out up to this point. These partic-
ulates consist essentially of aggregates of variable size. The quantity of particulates and their composition
depend on:
• The combustion process (an homogeneous air/fuel mixture minimizes particulate formation)
• The quantity of diesel (increasing the cetane index limits the number of particulates formed)
• The post-processing efficiency (only filtration allows the particulates to be removed efficiently)
The DPF is a porous structure with channels set out in such a way as to force the exhaust gases through the
chamber walls.
In normal operation, DPF captures all the particulates emitted by the engine and so fills up progressively. It
therefore becomes necessary to eliminate all the accumulated particulates, which is done by combustion
(regeneration).

REGULATION OF TEMPERATURE BEFORE DPF

Regulation of the exhaust gas temperature before DPF is needed to complete a secure regeneration. This
strategy uses both exhaust line injectors and late post injections (fuel injectors).
ECM computes the fuel mass flow injected by injectors (post injection) according to several parameters:
• Exhaust line temperature before DPF
• Atmospheric pressure
• Intake air temperature
• Differential pressure of the CSF
• Minimum level of fuel
• Engine speed
• Engine torque

COOLING FAN CONTROL

COOLING FAN CONTROL : System Description

INFOID:0000000010308983

SYSTEM DESCRIPTION

The cooling of the engine is done by a double speed motor driven fan unit (FAN1: small speed; FAN2: high
speed). The ECM controls cooling fan relays through CAN communication line.

When the engine is running

To cool the engine, a request for FAN1 activation is sent when the engine coolant temperature exceeds 94

°

C

(201

°

F) and a deactivated request is sent when the engine coolant temperature becomes lower than 92

°

C

(197

°

F).

When the engine coolant temperature continues to increase, a request for FAN2 activation is sent when the
engine coolant temperature exceeds 100

°

C (212

°

F) and a deactivated request is sent when the engine cool-

ant temperature becomes lower than 98

°

C (208

°

F).