Nissan Qashqai J11. Manual - part 367

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SYSTEM

TURBOCHARGER BOOST CONTROL : System Description

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DESCRIPTION

Turbocharger is used to increase the air pressure entering the engine. The turbocharger has two separate
chambers. The turbocharger consists of the following components:
• A chamber linked to the engine exhaust gas system
• A chamber linked to the engine air inlet system
• A turbine and a compressor, joined together by shaft.
The turbine, driven by exhaust gases, drives the compressor which compresses the inlet air.

CAUTION:

To stop the engine immediately after high-load driving, park the vehicle with the engine at idle before
turning OFF the ignition switch.
The boost pressure control is able to increase the manifold pressure with respect to the engine operating
point. The system has an electric solenoid valve connected on the vacuum circuit to control the flow of exhaust
gases through the turbine in order to generate high pressure in the boost circuit.

EGR SYSTEM

EGR SYSTEM : System Description

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DESCRIPTION

EGR (Exhaust Gas Recirculation) system reduces NOx emissions and improves fuel efficiency by recirculat-
ing exhaust gas into the intake manifold.
This engine has two EGR systems (low pressure and high pressure), and one of them is selected depending
on condition.

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The purpose of the low pressure EGR is to decrease fuel consumption.
The low pressure EGR system and the high pressure EGR system are not activated simultaneously.

LOW PRESSURE EGR SYSTEM

The low pressure EGR system recirculates exhaust gasses in the downstream DPF (Diesel Particulate Filter)
to the upstream turbocharger of intake air passage.
If EGR conditions are satisfied when engine coolant temperature is more than 70

°

C (158

°

F) and intake air

temperature is 20

°

C (68

°

F), the opening angle of the exhaust throttle valve is reduced and the low pressure

EGR volume control valve angle is adjusted to control EGR for achieving an appropriate EGR rate.

HIGH PRESSURE EGR SYSTEM

High pressure EGR system recirculates exhaust gasses in the exhaust manifold to the intake manifold.
If EGR conditions are satisfied when engine coolant temperature is less than 30

°

C (86

°

F), the opening angle

of the throttle valve is reduced and the EGR volume control valve angle is adjusted to control EGR for achiev-
ing an appropriate EGR rate.

EGR COOLING SYSTEM

The EGR cooler bypass is controlled by ON/OFF solenoid valve, connected to the vacuum circuit. Control is
determined according to the engine coolant temperature, intake air temperature, and the engine operating
point. The gases flow through the cooler during the EGR activation, except when the engine is cold; otherwise,
they go through the bypass. There is also a regular bypass activation function to prevent its clogging or jam-
ming.

THROTTLE CONTROL

THROTTLE CONTROL : System Description

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DESCRIPTION

This engine has two throttle valves. One of them is installed to the upstream of the intake manifold on the air
intake line and used for the high pressure EGR control and smooth engine stop. The other throttle valve is
installed to the downstream of DPF (Diesel Particulate Filter) on the exhaust line and used for the low pres-
sure EGR control.
These valves are normally open.

ELECTRIC THROTTLE CONTROL ACTUATOR

• During high pressure EGR control, the electric throttle control actuator reduces the opening angle of the

throttle valve and lowers pressure around the EGR feed port so that intake EGR gasses can be efficiently
taken in.

• When ignition switch is turned OFF, throttle valve is closed to stop the engine smoothly.
• In DPF regeneration mode, fresh air flow control uses only electric throttle control actuator (EGR valve is

fully closed).

EXHAUST ELECTRIC THROTTLE CONTROL ACTUATOR

The exhaust electric throttle control actuator reduces the opening angle of the exhaust throttle valve and intro-
duces exhaust gasses to the low pressure EGR system.

SWIRL CONTROL SYSTEM

SWIRL CONTROL SYSTEM : System Description

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DESCRIPTION

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SYSTEM

The swirl control valve mounted on the intake manifold generates swirl flow in the combustion chamber. This
swirl flow allows air mixture to become even, enabling the obtainment of the steady combustion.

ENGINE TORQUE CONTROL

ENGINE TORQUE CONTROL : System Description

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SYSTEM DESCRIPTION

The torque function can be explained by the following:
• Accessories torque management
• Engine torque losses
• Minimum available torque
• Maximum available torque
• Fast set-points to complete torque request
• Final torque requests setting

ACCESSORIES TORQUE MANAGEMENT

Air Conditioning Power

The amount of power absorbed by the air conditioning is useful for the engine control to compute the torque
requirement for air conditioning. Therefore, ECM can adapt dynamically the engine speed regulation depend-
ing on the load variations.
The power absorbed by the air conditioning depends on the refrigerant pressure and the compressor speed.
The air conditioning system power correction for idle speed regulation avoids engine speed undershoots and
overshoots at the compressor compressed volume variation.

Coolant Heaters or Air Heaters

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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 atmospheric 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

The ECM limits a engine torque in case of malfunction of engine component or ECM.