- Honda Car Owner's Manual

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70
VIBRATIONCONTROLSYSTEM
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.
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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.
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