8-VALVE 1.4
ENGINE
FIAT PUNTO TRAINING OUTLINE
Fiat Auto S.p.A.
After Sales Training
4.3.9 CVCP continuous phase variator
The Fire 1.4 8V engine is equipped with a continuous phase variator (
Continuos
Variable
Cam
Phaser
), i.e. a device capable of continuously modifying, during operation, the position of the
camshaft with respect to the drive shaft, thus obtaining an engine timing variation.
Thus, the engine will at any instant be operating with optimum timing in terms of fuel
consumption.
An approximate 5% reduction of consumption over the NEDC cycle is achieved.
The phase variator modifies the engine timing in the delay direction.
By delaying the intake valve opening and the exhaust valve closing, a portion of the intake
stroke (the greater the phase variator stepping, the greater such portion) will take place with
the intake valve closed and the exhaust valve still open, whereby a portion of the burnt gas will
be sucked by the exhaust (EGR). Such gas will take the place of a portion of the cylinder
volume (less displacement). In order to let the same amount of fresh air in, and achieve the
same engine performance (i.e. the same torque/power) at that operation point, the throttle will
have to be opened further. The engine operation (performance being equal) with the throttle
opened to a larger extent will reduce the pumping loss that occurs during the charge
replacement phase (exhaust/intake phases); thus, consumption will be reduced significantly.
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