To provide a worm reduction gear for suppressing the occurrence of a malfunction resulting from a rub of an abutment portion between an energization member and a bearing.SOLUTION: A first end part 21a of a worm shaft 21 is energized to a worm wheel 24 side via a first bearing 22 by an energization member 25. The worm shaft 21 has a tooth face forming part 21d and a tooth face non-forming part 21e which is formed between the first end part 21a and the tooth face forming part 21d. A shaft accommodation part 50 for accommodating the worm shaft 21 in a housing 20 includes: a substantially-straight part 80 extending in an axial direction X of the worm shaft 21 at a substantially-constant inside diameter; and a diameter-contracted part 90 which is arranged at the first end part 21a side rather than the substantially-straight part 80, and contracted in an inside diameter up to a position in which the diameter-contracted part is overlapped on the tooth non-formation part 21e from a position in which the diameter-contracted part is overlapped on a tooth face in the axial direction X.SELECTED DRAWING: Figure 2
【課題】付勢部材と軸受との当接部分の擦れに起因する不具合の発生を抑制するウォーム減速機を提供する。【解決手段】ウォームシャフト21の第1端部21aが、付勢部材25によって第1軸受22を介して、ウォームホイール24側に付勢される。ウォームシャフト21が、歯面形成部21dと、第1端部21aと歯面形成部21dとの間に形成された歯面非形成部21eとを有する。ハウジング20においてウォームシャフト21を収容するシャフト収容部50は、略一定の内径でウォームシャフト21の軸方向Xに延びる略ストレート部80と、略ストレート部80より第1端部21a側に配置され、軸方向Xにおいて歯面と重複する位置から歯面非形成部21eと重複する位置まで内径が縮径された縮径部90とを含む。【選択図】図2
WORM REDUCTION GEAR
ウォーム減速機
2019-02-28
Patent
Electronic Resource
Japanese