Electric power steering assembly

Patent metadata

Field	Value
Publication number	US-9440672-B2
Application number	US-201313803891-A
Country	US
Kind code	B2
Filing date	Mar 14, 2013
Priority date	Mar 14, 2013
Publication date	Sep 13, 2016
Grant date	Sep 13, 2016

Abstract

A rack drive assembly adapted for use in a vehicle electric power steering assembly includes a ball nut assembly having at least a first end portion and an opposite second end portion, a bearing assembly carried by the ball nut assembly for rotatably supporting the ball nut assembly, a pulley assembly configured to be carried by the ball nut assembly, and at least a first spanner nut configured to be carried by the first end portion of the ball nut for securing the bearing assembly on the ball nut assembly. The ball nut includes a flange provided on an outer portion thereof configured to connect the ball nut to a pulley of a pulley assembly for rotation therewith. The flange is spaced remote from an end of the second end portion of the ball nut.

First claim

What is claimed is:

1. A rack drive assembly adapted for use in a vehicle electric power steering assembly comprising:
a steering member configured to be disposed in a rack housing and including a rack portion operatively connected to a vehicle steering wheel and a screw portion;
a ball nut assembly configured to be operatively connected to the screw portion of the rack portion of the steering member for effecting axial movement of the steering member upon rotation of a vehicle steering wheel, the ball nut assembly including a one-piece ball nut having only a first end portion, an intermediate body portion and an opposite second end portion;
a bearing assembly configured to be disposed in the rack housing and carried by the intermediate body portion of the ball nut assembly for rotatably supporting the ball nut assembly relative to the steering member;
a pulley assembly configured to be carried by the ball nut assembly; and
a pair of spanner nuts disposed on opposite sides of the bearing assembly, the pair of spanner nuts including a first spanner nut configured to be screwed onto internal threads provided in an inner surface of the rack housing so as to engage an end surface of an outer race of the bearing assembly and a second spanner nut configured to be screwed onto external threads provided on the first end portion of the ball nut so as to engage an oppositely disposed end surface of the inner race of the bearing assembly;
wherein the ball nut includes a flange provided on an outer portion thereof configured to connect the ball nut to a pulley of the pulley assembly for rotation therewith, wherein the flange is located along a portion of the second end portion of the ball nut and is spaced apart from an end of the second end portion of the ball nut and the intermediate body portion of the ball nut, wherein the flange includes a plurality of openings configured to receive fasteners to connect the ball nut to the pulley.

2. The rack drive assembly according to claim 1 wherein the flange includes a plurality of first openings, the pulley including a plurality of second openings, wherein one of the plurality of first and second openings are threaded and the other one of the plurality of first and second openings are non-threaded through openings, and wherein the fasteners extend through the non-threaded openings and are secured in the threaded openings to connect the ball nut to the pulley.

3. The rack drive assembly according to claim 1 wherein the flange includes a plurality of threaded openings, the pulley including a plurality of non-threaded openings formed therethrough, and wherein the fasteners extend through the non-threaded openings and are secured in the threaded openings to connect the ball nut to the pulley.

4. The rack drive assembly according to claim 1 wherein the ball nut is stepped and further includes at least an intermediate body portion disposed between the first end portion and the second end portion, wherein the intermediate body portion defines a bearing seat for receiving the bearing assembly.

5. The rack drive assembly according to claim 4 wherein the first end portion defines a first outer diameter, wherein the intermediate body portion defines a second outer diameter greater than the first outer diameter and defines a bearing seat for receiving the bearing assembly, and wherein the second end portion defines a third outer diameter which is greater than the second outer diameter.

6. The rack drive assembly according to claim 4 wherein the second end portion is stepped and includes a first portion which defines a first outer diameter and a second portion which defines a second outer diameter, and wherein the flange is disposed on the second end portion between the first portion and the second portion and defines a flange outer diameter which is greater than the first outer diameter.

7. The rack drive assembly according to claim 1 wherein the pulley includes a flange provided thereon configured to be secured to the flange of the ball nut by the fasteners.

8. A rack drive assembly adapted for use in a vehicle electric power steering assembly comprising:
a steering member configured to be disposed in a rack housing and including a rack portion operatively connected to a vehicle steering wheel and a screw portion;
a ball nut assembly configured to be operatively connected to the screw portion of the rack portion of the steering member for effecting axial movement of the steering member upon rotation of a vehicle steering wheel, the ball nut assembly including a one-piece ball nut having only a first end portion, an intermediate body portion and an opposite second end portion, the first end portion provided with external threads at least along a portion thereof;
a bearing assembly configured to be disposed in the rack housing and carried by the intermediate body portion of the ball nut assembly for rotatably supporting the ball nut assembly relative to the steering member;
a pulley assembly configured to be carried by the ball nut assembly;
a pair of spanner nuts disposed on opposite sides of the bearing assembly, the pair of spanner nuts including a first spanner nut configured to be screwed onto internal threads provided in an inner surface of the rack housing so as to engage an end surface of an outer race of the bearing assembly and a second spanner nut configured to be screwed onto the external threads provided on the first end portion of the ball nut so as to engage an oppositely disposed end surface of the inner race of the bearing assembly; and
an electric motor configured to be operatively connected to the ball nut assembly by the pulley assembly;
wherein the ball nut includes a flange provided on an outer portion thereof configured to connect the ball nut to a pulley of the pulley assembly for rotation therewith, wherein the flange is located along a portion of the second end portion of the ball nut and is spaced apart from an end of the second end portion of the ball nut and the intermediate body portion of the ball nut, wherein the flange includes a plurality of openings configured to receive fasteners to connect the ball nut to the pulley.

9. The rack drive assembly according to claim 8 wherein the flange includes a plurality of first openings, the pulley including a plurality of second openings, wherein one of the plurality of first and second openings are threaded and the other one of the plurality of first and second openings are non-threaded through openings, and wherein the fasteners extend through the non-threaded openings and are secured in the threaded openings to connect the ball nut to the pulley.

10. The rack drive assembly according to claim 8 wherein the flange includes a plurality of threaded openings, the pulley including a plurality of non-threaded openings formed therethrough, and wherein the fasteners extend through the non-threaded openings and are secured in the threaded openings to connect the ball nut to the pulley.

11. The rack drive assembly according to claim 8 wherein the ball nut is stepped and further includes at least an intermediate body portion disposed between the first end portion and the second end portion, wherein the intermediate body portion defines a bearing seat for receiving the bearing assembly.

12. The rack drive assembly according to claim 11 wherein the first end portion defines a first outer diameter, wherein the intermediate body portion defines a second outer diameter greater than the first outer diameter and defines a bearing seat for receiving the bearing assembly, and wherein the second end portion defines a third outer diameter which is greater than the second outer diameter.

Assignees

• Trw Automotive Us Llc

Inventors

• Holm John

Classifications

• F16C35/063

  Fixing them on the shaft (with interposition of an element F16C35/07) · CPC title

• F16H55/36

  Pulleys (with features essential for adjustment F16H55/52) · CPC title

• F16H25/24

  Elements essential to such mechanisms, e.g. screws, nuts (F16H25/22 takes precedence) · CPC title

• Y10T74/18576

  including screw and nut · CPC title

• B62D5/0448 Primary

  Ball nuts · CPC title