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Thread: Video/pics: New Mirage MIVEC continuously variable valve control mechanism

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    Administrator MetroMPG's Avatar
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    Video/pics: New Mirage MIVEC continuously variable valve control mechanism

    On 3A92 1.2 L and 3A90 1.0 L engines

    MIVEC = Mitsubishi Innovative Valve timing Electronic Control system

    This video demonstrates how the new Mitsu MIVEC system achieves continuously variable "valve lift, the valve open interval, and the opening-closing time."

    The video demonstrates MIVEC only on the intake side for a SOHC engine. The new Mirage engines are DOHC, but MIVEC is only on the intake side.

    (Note for anyone looking at the Wikipedia entry for MIVEC: it appears to describe the earlier version of MIVEC which was a "cam profile swapping" approach (not continuously variable). )

    Video title: MITSUBISHI The Mechanism of the New MIVEC



    Video posted: Sept, 2012

    Titles from the video:

    1. The new MIVEC engine with a continuously variable valve lift mechanism designed for low fuel consumption
    2. Components of the new MIVEC engine
      Swing cam components and a center rocker arm are built into a simple SOHC structure
      - Swing cam components: Swing cam shaft, Swing cam, Spring
      - Rotating [conventional] cam
      - Center rocker arm
      - Intake rocker arm (double-headed)
      - Control shaft (Intake rocker shaft)
    3. The new MIVEC Engine Works
      The range of motion of the oscillating [swing] cam is made continuously variable by moving the fulcrum position of the center rocker arm through rotation of the control shaft (Intake rocker shaft) by an electric motor
    4. The movement of the intake valve, which continuously and simultaneously varies the valve lift, the valve open interval, and the opening-closing time, is optimized at all times based on the engine running conditions.
      - High output, Low fuel consumption, Low exhaust emission
    5. The engine supports low fuel consumption and reduction of the environmental load.
      - Economy, Ecology
    From Mitsu's technical library: http://www.mitsubishi-motors.com/en/...ary/mivec.html

    The all-new continuously-variable valve system make valve lift stroke, the length of valve-opening time and valve opening timing continuously and simultaneously variable through a control shaft (see figure below).
    With this mechanical interlock structure, cooperative control of hydraulic variable valve timing phase system becomes unnecessary. Accordingly the new MIVEC system can be adopted to the simple SOHC structure.
    Consequently the new MIVEC realizes light weight and compact new engine.
    Name:  smart-mivec_im_03.jpg
Views: 4650
Size:  21.2 KB



    The all-new variable-valve structure simply adds an oscillating cam, a support shaft, and a center rocker arm to the conventional SOHC's rotating cam, rocker arm and rocker shaft. The range of motion of the oscillating cam is made continuously variable by moving the fulcrum position of the center rocker arm through rotation of the control shaft (intake rocker shaft) by an electric motor.
    It's always interesting to see how different companies approach valve control systems in a way that they can call their own. (And avoid infringing the patents of their competitors! )


        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage base ES 1.2 manual: 54.0 mpg (US) ... 23.0 km/L ... 4.4 L/100 km ... 64.9 mpg (Imp)


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    Administrator MetroMPG's Avatar
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    This beats the heck out of the valve timing in both my 3-cylinder cars:


    • The Honda Insight's 1.0L has VTEC-e (dual profile swapping; non-continuously variable).



    • The Suzuki 1.0L in my Firefly/Metro has ... well, none! Actually, that's not quite true: it has a "manual dual-profile cam" approach. However, for the sake of convenience, I leave the economy profile cam in the car all the time; the normal profile cam is currently sitting on top of the dresser in my bedroom!!

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage base ES 1.2 manual: 54.0 mpg (US) ... 23.0 km/L ... 4.4 L/100 km ... 64.9 mpg (Imp)


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    Senior Member jamiec's Avatar
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    My Suzuki carry does not hav a cam It would be interesting if we can find out the engines power and torque curves.

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    Administrator Daox's Avatar
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    Ditto. I've looked around a bit, but I haven't been able to find anything on the engine's development or anything... yet.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 automatic: 49.0 mpg (US) ... 20.8 km/L ... 4.8 L/100 km ... 58.8 mpg (Imp)


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    Found more info from a Mitsu "Technology Library" page; updated the first post with diagram & further explanation of operation.

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage base ES 1.2 manual: 54.0 mpg (US) ... 23.0 km/L ... 4.4 L/100 km ... 64.9 mpg (Imp)


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    Still not 100% clear on whether the system is on intake & exhaust, but just found this official Mistu info:

    The maximum output and torque of the new MIVEC engine nearly match the levels of conventional engines. The engine also employs a continuously variable valve mechanism that constantly changes the intake valve timing and the exhaust valve lift. By providing precise adjustments with the intake valve of the amounts of air needed for combustion, the mechanism reduces air intake pumping losses and enhances fuel economy, lowering CO2 emissions.
    Source: (PDF) Social and Environmental Report 2012 - MITSUBISHI MOTORS CORPORATION

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage base ES 1.2 manual: 54.0 mpg (US) ... 23.0 km/L ... 4.4 L/100 km ... 64.9 mpg (Imp)


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    FYI, a Mirage reviewer from the Philippines let me know that MIVEC is on the intake side only.

    I'm sure Mitsu will update their technical library soon enough.

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage base ES 1.2 manual: 54.0 mpg (US) ... 23.0 km/L ... 4.4 L/100 km ... 64.9 mpg (Imp)


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    Senior Member jamiec's Avatar
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    I expected they would have it on both intake and exhaust Maybe there is room there for Mitsu to add it to the exhaust later and improve the cars power and economy when the competition heats up.

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    I'm not too surprised its only on the intake side. That is where the largest gains are and they're also trying to keep costs down as much as they can. Many manufacturers have done this.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 automatic: 49.0 mpg (US) ... 20.8 km/L ... 4.8 L/100 km ... 58.8 mpg (Imp)


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    Quote Originally Posted by Daox View Post
    I'm not too surprised its only on the intake side. That is where the largest gains are and they're also trying to keep costs down as much as they can. Many manufacturers have done this.
    So would that mean it doesn't have that sound when it hits a certain RPM?



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