Worm reducer and method for assembling same

A worm reducer comprising:

• a housing including a wheel accommodating portion and a worm accommodating portion that is disposed at a skew position with respect to the wheel accommodating portion and whose an axially intermediate portion opens to the wheel accommodating portion;
• a worm wheel having wheel teeth on an outer circumferential surface thereof and configured to be rotatably supported inside the wheel accommodating portion;
• a worm having worm teeth that meshes with the wheel teeth on an outer circumferential surface thereof and configured to be rotatably supported inside the worm accommodating portion;
• a holder having a protruding portion that includes two guide portions spaced apart from each other in a third direction orthogonal to both a first direction, which is a direction in which a tip end portion of the worm moves toward and away from the worm wheel, and a second direction, which is an axial direction of the worm accommodating portion, and two holder engagement portions provided on inner side surfaces of the two guide portions facing each other, the holder being disposed between the tip end portion of the worm and the worm accommodating portion;
• a pad having a pad base portion that is disposed between the two guide portions, two pad engagement portions that are provided on side surfaces on both sides of the pad base portion in the third direction and are in contact with the two holder engagement portions, and a pad elastic pressing portion that elastically presses a part of the holder in the second direction to apply a preload to a contact portion between the holder engagement portion and the pad engagement portion, the pad being externally fitted to the tip end portion of the worm;
• and
• an elastic member installed to extend over the protruding portion and the pad base portion and configured to elastically bias the tip end portion of the worm toward a worm wheel side via the pad, wherein
• the holder or the pad includes a first grease supply portion for supplying grease to a contact portion between the elastic member and the pad base portion in the vicinity of the contact portion between the elastic member and the pad base portion, and
• the holder includes a second grease supply portion for supplying grease to a contact portion between the elastic member and the protruding portion in the vicinity of the contact portion between the elastic member and the protruding portion.