Abstract
This paper describes about the new worm gear for EPS (Electric Power
Steering) and about the effect of the reduction of the contact stress of the worm gear.
In conjunction with recent trends in vehicles getting larger and tires gaining larger footprints,
the EPS motor assist torque has increased considerably. This leads to the issue involving
enlargement of the external diameter of the worm gear and the worm wheel gear, which are
reduction gears that boost motor torque.
In order to address this issue, the authors examined single-threaded worm gears, and
fundamental factors that cause the enlargement of the external diameter of worm wheel from
the standpoint of the mesh of the gear. To solve the fundamental factors, a new worm gear
that addressed this issue is proposed.
This new worm gear was examined about contact stress and contact stress could be reduced in
this proposed new worm gear compared to the conventional worm gear.
These gears are manufactured, and they are checked by a durability test and the proposed
worm gear is verified that durability performance could be improved under the same
transmission torque.
Keywords: EPS, worm gear, tooth profile, mesh, contact stress