| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive speed reducer capable of suppressing energy loss and reducing gear-noise and an electric power steering device having the speed reducer. SOLUTION: A projected part 54 is formed on the tooth crest of a tooth 51 of a synthetic resin member 12b of a worm wheel 12 to reduce a bottom clearance between the tooth 51 of the worm wheel 12 and a worm 11. In an engagement region A, the tip 55 of the projected part 54 is slid on the tooth bottom 56 of the worm 11 while producing proper frictional resistance. An impact speed in tooth contact resulting from backlash can be sufficiently suppressed and rattling noise of gear can be reduced. COPYRIGHT: (C)2004,JPO&NCIPI
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