SFI SYSTEM

Info Added 2017-04-18


  1. CONSTRUCTION


    1. The basic components of the continuously variable valve lift controller assembly are an EDU, a brushless motor and a differential roller converter.

    2. The internal gears of the continuously variable valve lift controller assembly are lubricated by engine oil.

    3. A neodymium magnet* is used in a flat brushless motor to achieve a compact construction. The flat brushless motor is a DC motor from which the brushes and the commutator have been eliminated. A multipolar magnetized magnet acts as a rotor, which switches the polarity of the voltage applied to the surrounding stator actuation coil in sync with the rotation of the rotor. The resulting alternating field and the rotor magnet magnetic flux cause attraction and repulsion to generate torque.

      Tech Tips

      *: A neodymium magnet is a type of rare earth magnet composed primarily of neodymium, iron and boron. The neodymium magnet has a high magnetic flux density to provide extremely strong magnetism.

    4. The EDU operates the motor in accordance with signals from the ECM. The differential roller converter converts the rotational movement of the motor into a linear movement. This linear movement operates the VALVEMATIC mechanism.

      A001MJVC01
      *1 Continuously Variable Valve Lift Controller Assembly *2 EDU
      *3 Stator *4 Rotor/Motor
      *5 Bearing *6 Differential Roller Converter
      *a Continuously Variable Valve Lift Controller Assembly Cross Section *b Motor Portion
      *c

      Sensor Portion


      • Motor Position Sensor

      • Action Angle Sensor

      		 - -
      B003XF2 Engine Oil Out B003XH4 Engine Oil In
      A001N4B Linear Movement A001NBB Rotational Movement

    5. The motor rotates the nut on the differential roller converter. The movement of the nut travels to the pinion and the planetary gear and causes the sun shaft to move linearly.

      Figure 1. Differential Roller Converter

      A001N4RC01
      *1 Pinion *2 Sun Gear
      *3 Planetary Gear *4 Sun Shaft
      *5 Ring Gear *6 Nut
      B003XF2 Rotational Movement B003XH4 Linear Movement

  2. OPERATION


    1. On the basic control, the ECM determines the target intake air volume in accordance with the accelerator pedal depressed angle, engine speed and various sensor signals. The EDU, which is integrated into the continuously variable valve lift controller assembly, determines the target amount of lift and the action angle of the intake valve in accordance with signals from the ECM.

      Figure 2. Basic Control Flow Chart

      A001MWIE01

    2. To optimize the valve opening and closing timing, the VALVEMATIC effects coordinate control with the dual VVT-i. Thus, the VALVEMATIC controls the amount of valve lift and the action angle in accordance with the driving conditions. Because the VALVEMATIC features timing advance characteristics in which the amount of valve lift and the action angle vary, it effects the proper control to attain the intended amount of valve lift. This VVT-i has timing advance characteristics that differ from the conventional dual VVT-i control.

      Figure 3. VALVEMATIC Operating Range

      A001NB6E10

      Figure 4. Valve Opening and Closing Graph

      A001MIGE08
      *1 Exhaust Valve
      *2 Intake Valve
      *3 Amount of Valve Lift
      *4 The exhaust valve opening timing is adjusted in accordance with the timing intake valve opening timing. Thus, by closing the intake valve early, fuel economy is improved.

      Figure 5. Relationship between Intake Valve Action Angle and VVT-i

      A001N9WE02

    3. The following table shows the coordinated control of the VALVEMATIC with ETCS-i during basic control:

      Control Operation
      Starting Control VALVEMATIC controls the intake valve action angle, and ETCS-i operates the throttle valve to control the intake air volume.
      Fast Idle Control
      Before Warm-up Control
      After Warm-up Control

      • VALVEMATIC controls the amount of intake valve lift and the intake valve timing, and ETCS-i opens the throttle valve wider than the normal opening and reduces the intake manifold negative pressure in order to minimize pumping loss.

      • During idling, when the intake air volume is small, the ETCS-i controls the intake air volume as in the past.
      Engine Stop Control