HONDA Insight - Manual (Page 70)

70
V
IBRATION
C
ONTROL
S
YSTEM
A three cylinder engine, without balance shafts (which decrease power and thus fuel efficiency), is
inherently prone to vibration. To improve idle quality, the IMA motor is used to smooth out speed
fluctuations in the engine's crankshaft.
During a power stroke, the crankshaft speed increases, and the IMA momentarily switches to the
regeneration mode to absorb a little of the power pulse. After the power pulse has been absorbed, the IMA
is activated in assist mode to speed up the slowing crankshaft. The results are a much more consistent
crankshaft rotational velocity and smoother idle quality.
The Insight also uses lightweight aluminum-alloy engine mounting brackets that incorporate hydraulic
(liquid-filled) mounts that help damp engine vibration. The mounts are located on the axis of the engine's
principal inertial moment (the axes about which the engine vibrates). At these points, the least amplitude of
engine vibration is transmitted from engine to frame, which significantly reduces engine-idle vibration.