Patent ID: 11867264
Assignee: NSK LTD.
Field: Mechanical elements (Mechanical engineering)
Classification: CPC F | IPC F

Claim 0:
1. A ball screw device comprising:
a screw shaft including: a screw portion having a shaft-side ball thread groove having a spiral shape on an outer-circumferential surface thereof, and a fitting shaft portion having an outer diameter smaller than an outer diameter of the screw portion and arranged adjacent to one side in an axial direction,
a nut including: a nut-side ball thread groove having a spiral shape on an inner-circumferential surface thereof, and a first engaging portion at an end portion on the one side in the axial direction,
balls arranged between the shaft-side ball thread groove and the nut-side ball thread groove,
a stopper including: a boss portion externally fitted to the fitting shaft portion so as not to be able to rotate relative to each other, and a second engaging portion protruding in a radial direction from an outer-circumferential surface of the boss portion and engageable with the first engaging portion in a circumferential direction, and
a holding member arranged adjacent to the one side in the axial direction of the stopper such that the stopper is held between the holding member and the screw portion in the axial direction, and
the ball screw device transmitting an axial load between the screw portion and the holding member through the stopper without applying a moment to the stopper,
wherein the stopper includes: a first contact surface configured by a flat surface existing on a virtual plane perpendicular to a center axis of the stopper and having a rotationally symmetrical shape in relation to the center axis of the stopper, on a side surface on the one side in the axial direction so as to contact the holding member, and a second contact surface configured by a flat surface existing on a virtual plane perpendicular to the center axis of the stopper and having a rotationally symmetrical shape in relation to the center axis of the stopper, on a side surface on the other side in the axial direction so as to contact the screw portion,
wherein the first contact surface is configured by a side surface on the one side in the axial direction of the boss portion, and the second contact surface is configured by a side surface on the other side in the axial direction of the boss portion, and
wherein a side surface on the one side in the axial direction of the second engaging portion is arranged so as to be shifted in the axial direction to the other side in the axial direction with respect to the side surface on the one side in the axial direction of the boss portion, and a side surface on the other side in the axial direction of the second engaging portion is arranged so as to be shifted in the axial direction to the one side in the axial direction with respect to the side surface on the other side in the axial direction of the boss portion.