СИСТЕМА SFI


  1. FUNCTION


    1. The Dual VVT-i system is designed to control the intake and exhaust camshaft within a range of 40° and 35° respectively (of crankshaft angle) to provide valve timing that is optimally suited to the engine operating conditions. This improves torque in all the speed ranges as well as increasing fuel economy, and reducing exhaust emissions.

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      *1 Camshaft Timing Oil Control Valve Assembly (Exhaust RH) *2 Camshaft Timing Oil Control Valve Assembly (Intake RH)
      *3 Camshaft Position Sensor (Exhaust RH) *4 Engine Coolant Temperature Sensor
      *5 Camshaft Timing Oil Control Valve Assembly (Intake LH) *6 Camshaft Position Sensor (Exhaust LH)
      *7 Camshaft Timing Oil Control Valve Assembly (Exhaust LH) *8 Camshaft Position Sensor (Intake LH)
      *9 Crankshaft Position Sensor *10 Camshaft Position Sensor (Intake RH)
      *11 ECM *12 Intake Mass Air Flow Meter Sub-assembly
      *13 Throttle Position Sensor - -
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    2. The VVT-i system delivers excellent benefits in the different operating conditions as follows:


      1. During Idling

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        *1 TDC
        *2 Earliest Timing (EX)
        *3 Latest Timing (IN)
        *4 BDC
        Objective Effect
        Eliminating overlap reducesblow back to the intake side.

        • Stabilized idling speed

        • Better fuel economy

      2. At Light Load

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        *1 TDC
        *2 Earliest Timing (EX)
        *3 Latest Timing (IN)
        *4 BDC
        Objective Effect
        Eliminating overlap reducesblow back to the intake side. Engine stability is ensured

      3. At Medium Load

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        *1 TDC
        *2 To Advance Side (IN)
        *3 To Retard Side (EX)
        *4 BDC
        Objective Effect
        Increasing overlap increasesinternal EGR, reducing pumpinglosses.

        • Better fuel economy

        • Improved emissioncontrol

      4. In Low to Medium Speed Range with Heavy Load

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        *1 TDC
        *2 To Retard Side (EX)
        *3 To Advance Side (IN)
        *4 BDC
        Objective Effect
        Advancing the intake valveclosing timing improvesvolumetric efficiency. Improved torque in low tomedium speed range

      5. In High Speed Range with Heavy Load

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        *1 TDC
        *2 To Retard Side (IN)
        *3 To Advance Side (EX)
        *4 BDC
        Objective Effect
        Retarding the intake valveclosing timing improvesvolumetric efficiency. Improved output

      6. At Low Temperatures

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        *1 TDC
        *2 Earliest Timing (EX)
        *3 Latest Timing (IN)
        *4 BDC
        Objective Effect
        Eliminating overlap to reduceblow back to the intake sidestabilizes the idling speed at fastidle.

        • Stabilized fast idle speed

        • Better fuel economy

      7. Starting Engine and Stopping Engine

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        *1 TDC
        *2 Earliest Timing (EX)
        *3 Latest Timing (IN)
        *4 BDC
        Objective Effect
        Eliminating overlap minimizesblow back to the intake side. Improved startability