FUEL SYSTEM


  1. FUNCTION


    1. The Direct injection 4-stroke gasoline engine Superior version (D-4S) system has 2 fuel injection methods. One is the in-cylinder direct injection method that directly injects pressurized fuel into the combustion chamber. The other is the intake port injection method. The ECM determines which fuel injection method to use in accordance with the engine conditions.

    2. When the engine is in the low to middle load range, the direct injection method or port injection method is used, or both methods are used together, to improve fuel economy and achieve low emissions by achieving a homogeneous air-fuel mixture and stable combustion. Also, only the direct injection method is used when the engine is in the high load range. As a result, engine output performance is improved while high compression is achieved by reducing knocking and improving the effect of charging due to cooling the intake.

    3. Directly after a cold engine start, fuel is injected from the fuel injector assembly (for direct injection) during the compression stroke while the air-fuel mixture in the combustion chamber homogenizes due to the injection of fuel from the fuel injector assembly (for port injection). As a result, the air-fuel mixture is stratified around the spark plug to enable a large retarded angle during ignition timing, increase the exhaust gas temperature and quickly warm the catalyst.

    4. A 1-hole type high pressure slit nozzle fuel injector assembly (for direct injection) is used. Fuel is highly atomized and spread over a wide fan-shaped area from the injection hole. At the same time, the fuel is mixed with a high amount of air and injected into the combustion chamber. High performance and high engine output are achieved by circulating intake air into the combustion chamber vertically (tumble flow) to promote the mixing of fuel and air.*1


      • *1: Models without gasoline particulate filter (GPF) system

    5. A high-pressure injector with multiple injection holes (6-hole type) in which the injection angle is optimized and fuel is highly atomized is used for the direct fuel injector assembly. Highly pressurized and atomized fuel promotes the mixing of fuel and air by following a vertical swirl flow (tumble flow) to achieve high performance and high engine output.*2


      • *2: Models with gasoline particulate filter (GPF) system

      Figure 1. D-4S System

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      Figure 2. Fuel Injection Directly after a Cold Start

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      *1 From expansion stroke to intake stroke: Before the intake valve opens, fuel is injected into the intake port from the fuel injector assembly (for port injection).
      *2 Intake stroke: The intake valve opens and the homogeneous air-fuel mixture is drawn into the combustion chamber.
      *3 Compression stroke: During the latter half of the compression stroke, fuel is injected into the combustion chamber from the fuel injector assembly (for direct injection).
      *4 Expansion stroke: The stratified air-fuel mixture around the spark plug is ignited.