Ball screw unit
AssigneeJtekt Corporation
InventorsHajime Watanabe, Satoshi Kondo, Yasuhiro Ohta
Life of this patent
Estimating the term…
Abstract
The outer diameter of a spline nut and the inner diameter of a nut body holding portion of a housing gradually decrease in the downward direction. A ball screw protection unit includes a nut body taper face that is formed in the outer peripheral face of the spline nut, a holding portion taper face that is formed in the nut body holding portion, and a disc spring that is provided at the upper end of the spline nut and that biases the spline nut in such a direction that a friction force between the nut body taper face and the holding portion taper face increases (downward direction).
Claims10
A ball screw unit, comprising:
- a screw shaft that has a groove;
- a nut that is fitted to the groove of the screw shaft via balls and that has an outer diameter which gradually decreases in a predetermined direction;
- a nut holding portion that is provided on an outer peripheral face of the nut, that holds the nut, and that has an inner diameter which gradually decreases in the predetermined direction in accordance with a gradual decrease in the outer diameter of the nut;
- and
- a nut biasing member that biases the nut in the predetermined direction in which the outer diameter of the nut and the inner diameter of the nut holding portion gradually decrease, wherein
- the outer diameter of the nut and the inner diameter of the nut holding portion gradually decrease in such a manner that when a force that proceeds in a direction opposite to a direction of the biasing force of the nut biasing member and that overcomes the biasing force is applied to the nut, a friction force between the outer peripheral face of the nut and an inner peripheral face of the nut holding portion decreases to allow relative movement between the nut and the nut holding portion.
Dependencies are inferred from the claim text.