GENERAL : HDI DIRECT INJECTION SYSTEM

FOR 1C2X AND B0F7C AND DVY01 AND SINCE O 8001 OR

FOR 1CN6 AND B0F2X AND DVY01 AND SINCE O 8211 TO O 8687 OR

FOR 1CN7 AND B0F2X AND DVY01 AND SINCE O 8688 OR

FOR 1CX4 AND B0F2X AND DVY01 AND SINCE O 8688 OR

FOR 1CX4 AND B0F7C AND DVY01 AND SINCE O 8688 OR

FOR 1CU6 AND B0F7C AND DVY01 AND SINCE O 8276 OR

FOR 2CM4 AND B0F2X AND DVY01 AND SINCE O 8358 OR

FOR 1C6N AND B0F2X AND DVY01 AND SINCE O 8365 OR

FOR 2CU6 AND B0F7C AND DVY01 AND SINCE O 8421 OR

FOR 2CU6 AND B0F7U AND DVY01 AND SINCE O 8421


1 - Preamble

The development of a new DW10 engine range means that a powerful new direct injection system can be used.

The HDI direct injection system takes account of the requirements of the year 2000 relating to the following components :
  • Emission standard.
  • Improvement of driving performance.
  • Fuel savings.
  • Mechanical reliability.

    1.1 - Emission standard.

    Fuel combustion causes the emission of the following pollutants :
  • Carbon dioxide (CO2).
  • Carbon monoxide (CO).
  • Non-burned hydrocarbons (HC).
  • Nitrogen oxides (No.x).
  • Carbon particles.
    Antipollution regulations are becoming stricter and lead to the following developments :
  • Installation of an exhaust gas recycling device (EGR) which reduces nitrogen oxide emissions (NOx).
  • Reduction in the amount of sulphur in the fuel (SO2).

    The improvement in the quality of diesel means that oxidising catalytic converters can be fitted on diesel vehicles.

    Fitting an oxidising catalytic converter reduces the following pollutants :
  • Carbon monoxide (CO).
  • Non-burned hydrocarbons (HC).
  • Carbon particles.

    NOTE : EGR : exhaust gas recycling device.

    1.2 - Principal structural features of the DW10 engine.

    Up until now, the diesel engines fitted to touring vehicles have used indirect injection systems.

    In an indirect injection system, the fuel is injected into a precombustion chamber under a maximum pressure of 300 bar.

    In a direct injection system, the fuel is injected directly into the top of the pistons.

    Engine efficiency is improved due to the following factors :
  • Better quality of the air/fuel mixture.
  • Reduction in thermal losses.
  • Direct combustion in the cylinders.
    Features of the new cylinder head design on the DW10 engine :
  • No precombustion chamber.
  • Specific location of the heater plugs.
  • Specific location of the diesel injectors.
    Modifications for improving the efficiency of DW10 engines :
  • Roller valve rockers limiting losses caused by friction.
  • Optimisation of inlet and exhaust hoses.
  • Weight reduction.

    NOTE : The above modifications also directly help to reduce pollutant emissions.

    1.3 - Injection system.

    Traditional direct injection diesel engine (e.g. DJ5 TED engine) :
  • Injecting the fuel directly into the top of the pistons improves engine efficiency (thermal losses are reduced).
  • Direct injection is performed by a rotary distributor driven mechanically by the engine.
  • The injection pressure at the pump outlet cannot exceed 300 - 400 bar when idling and 900 bar at high engine speed.

    NOTE : Given the disadvantages caused (lack of flexibility and combustion noise), this direct injection system is not used on private vehicles.

    2 - Principle of HDI direct injection

    The device, developed in collaboration with BOSCH, is used to work out an ideal injection law.

    Injection occurs at very high pressures using a common injection rail with electrohydraulic injectors (called common rail).

    The common injection rail is held at a very high pressure.

    The injection pressure may reach 1350 bar at high engine speeds.

    The injection ECU incorporates the following parameters :
  • Engine speed.
  • Engine coolant temperature.
  • Air temperature.
  • Temperature of fuel.
  • Fuel pressure.
  • Atmospheric pressure.
  • Position of the accelerator pedal.
    Functions of the injection ECU :
  • To work out the injection duration from the fuel pressure.
  • To control a pre-injection (to reduce combustion noise) if required and the main injection.
  • To control the fuel flow injected by the electrohydraulic injectors.
    Advantages of the electronic management of the injection system :
  • Improvement of driving performance (50% additional torque at low engine speeds and 25% more power).
  • Increase in engine efficiency (fuel saving of around 20%).
  • Reduction in pollutant emissions (CO2, CO, HC and carbon particles).

    NOTE : Post-injection combined with a nitrogen oxide catalytic converter can reduce the quantity of nitrogen oxide as well as other pollutants.

    3 - Variations of the HDI direct injection system

    Motor / equipment mechanical features
    6 Specific cylinder head with 2 valves per cylinder
    Controlled turbocharger (injection ECU + electrovalve)
    Air/air heat exchanger
    5 Specific cylinder head with 2 valves per cylinder
    Air/air heat exchanger
    Non-controlled turbocharger
    6 Specific cylinder head with 2 valves per cylinder
    No air/air heat exchanger
    Soft blown (depollution turbocharger)

    4 - Safety instructions


    NOTE : Safety advice is detailed in a brochure in the mechanical binder for the vehicle concerned.

    IMPORTANT : Given the very high pressures in the high pressure fuel circuit (1350 bar), follow the instructions below.

    No smoking near to the high pressure circuit during repair work.

    Avoid working near to a naked flame or sparks.

    Engine running :
  • Do not work on the high pressure fuel circuit.
  • Always remain out of the way of a possible jet of fuel which may cause serious injury.
  • Do not place your hand near to a leak on the high pressure fuel circuit.
  • After switching off the engine, wait for 30 seconds before starting any repair work.

    NOTE : This period of time is required to allow the high pressure fuel circuit to return to atmospheric pressure.