Page 17 - E BOOK ENGINE MECHANICAL M2

2. MIVEC ENGINES

<Construction & Operation>
The structure has a T-lever that rides on the high lift cam lobe which is located between the rocker
arms driven by the low lift cams lobes.
In the low speed mode, the intake valves are operated by the rocker arms that are riding on the low
lift cam lobes because the wing of the T-lever does not touch the switching pistons built-in into the
rocker arm. So the T-lever is moving freely. In the high speed mode, the oil pressure is applied at
the bottom of the switching pistons, and these are pushed up. When the switching pistons are up,
the wing of the T-lever touches the pistons that block the free travel. This forces the T-lever to actu-
ate on the rocker arm as it rides on the high lobe of the cam, and both intake valves are operated
simultaneously.

Intake high lift cam Free Wing of T-lever
Intake low lift cam

Exhaust Switching piston Holder
rocker shaft

Low Speed Mode
Intake rock- Touch
er shaft Oil pressure

Rocker arm piston

Fig. 2-9
High Speed Mode

Accumulator Switching piston
The cam switching is carried out when the engine speed
reaches a specified speed.
An accumulator ensures that there is an oil pressure
available at the switching moment to prevents switching
delays.
The oil passage is divided into two in front of the oil con-
trol valve (OCV).
Engine oil is always supplied to the exhaust rocker shaft
for lubrication, and a reduced oil pressure is supplied for
lubrication to the intake rocker shaft through the oil feed-
er control valve (OCV) before low to high lift switching
occurs.

Oil feeder control valve from oil pump

Fig. 2-10

2 - 5 Pub. No. PTAE1225