Rack assist type power steering apparatus
US10220874B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jul 12, 2016 |
| Grant date | Mar 5, 2019 |
| Priority date | — |
| Expiry date | Apr 4, 2037 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16H25/2204
- WIPO fieldTransport
- WIPO sectorMechanical engineering
Abstract
The present disclosure relates to a rack assist type power steering apparatus that includes: a ball nut that is rotated by the rotating force transmitted from a motor and has an internal screw groove formed in the inner circumferential surface thereof; and a rack bar that has an external-screw-groove-formed part that has an external screw groove formed in the outer circumferential surface thereof, and is coupled with the ball nut by a ball, wherein the external screw groove has a first curved portion and a second curved portion connected to each other, and is formed such that a contact angle formed by a line that is normal to a tangent line at a point where the ball makes contact with the first curved portion and a line that is normal to a tangent line at a point where the ball makes contact with the second curved portion gradually decreases from the central portion toward opposite end portions of the external-screw-groove-formed part, thereby reducing friction generated when the ball performs a rolling motion in the middle of the external screw groove that is formed in the rack bar and distributing the load acting on the ball in the opposite end portions of the external screw groo…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.