- Honda Car Owner's Manual

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ElectronicConstruction
The EPS control unit is mounted inside the car on the right side bulkhead, underneath thedash. It
receivesinputfromthevehiclespeedsensorandtorquesensormountedonthesteeringpinionshaft.
ThetorquesensorisidenticalinconstructiontotheunitontheS2000.Thepinionshaftengagesthe
piniongearviaatorsionbar,whichtwistsslightlywhenthereisahighamountofsteeringresistance.The
amountoftwistisinproportiontoboththeamountofresistancetowheelturning,andtothesteeringforce
applied. A pin on the torsion bar engages a diagonal slot in the sensor core, which movesup or down
dependingontheamountoftorsionbartwist,andthedirectionofrotation.Twocoilssurroundingthecore
detectboththeamount,andthedirectionofmovement.
Usingthisinformation,theEPScontrolunitdeterminesboththeamountofsteeringassistrequired,and
thedirection.Itthensuppliescurrenttothemotorforsteeringassist.Theamountofassistisalsomodified
inproportiontovehiclespeedtomaintaingoodsteeringfeel.
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TorqueSensor
The torque sensor is a device to detect steering turning direction and read resistance. The sensing
sectionofthetorquesensorconsistsoftwocoilsandacore(slider).Thesteeringinputshaftandpinion
gear are connected via a torsion bar. The slider is engaged with the pinion gear in a way that it turns
togetherwiththepiniongearbutcanmovevertically.Aguidepinisprovidedontheinputshaftandthepin
isinaslantgrooveontheslider.
Whenroadresistanceislow,thesteeringinputshaft,piniongearandsliderturntogetherwithoutthe
slider'sverticalmovement.
Whenroadresistanceishigh,thetorsionbartwistsandcausesadifferenceofsteeringanglebetween
theinputshaftandpiniongear.Inotherwords,theturningangleoftheguidepinandsliderdiffer,andthe
guidepinforcestheslidertomoveupwardordownward.
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