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

[MetroMPG]

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.

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! )