BELT TYPE DRIVELINE AND RACK ASSIST TYPE ELECTRIC POWER STEERING APPARATUS HAVING THE SAME

• US 20130048411A1
• Filed: 08/31/2012
• Published: 02/28/2013
• Est. Priority Date: 08/31/2011
• Status: Active Grant

• Current Assignee: HL Mando Corporation (Halla Holdings Corporation)
• Original Assignee: Mando Corporation (Halla Holdings Corporation)
• Inventors: LEE, Je Ho
• Granted Patent: US 8,789,648 B2
• Time in Patent Office: Days
• US Class Current: 180/444
• CPC Class Codes: B62D 5/0427 the axes being coaxial
• CPC Class Codes: B62D 5/0448 Ball nuts
• CPC Class Codes: F16H 2025/2081 Parallel arrangement of drive motor to screw axis
• CPC Class Codes: F16H 2025/2096 using endless flexible members
• CPC Class Codes: F16H 25/20 Screw mechanisms with automatic reversal F16H25/12
• CPC Class Codes: F16H 25/2204 with balls
• CPC Class Codes: F16H 25/24 Elements essential to such mechanisms, e.g. screws, nuts F16H25/22 takes precedence
• CPC Class Codes: F16H 55/14 Construction providing resilience or vibration-damping F16H55/06 takes precedence
• CPC Class Codes: Y10T 74/18576 including screw and nut

Abstract

Disclosed are a belt type driveline and a rack assist type electric power steering apparatus including the belt type driveline, which improve power transmission efficiency and increases durability by preventing spinning with no traction of a ball nut and a nut pulley due to a slip between the ball nut and the nut pulley in an operation of a belt by a motor, and provide a user with convenient steering by minimizing vibration and noise transferred through a rack bar, the ball nut, the nut pulley, etc., when the rack bar slides while the nut pulley and the ball nut rotate.

Claims

1. A belt type driveline comprising:

a ball nut engaged with a rack bar and configured to slide the rack bar;

a nut pulley engaged with an outer peripheral surface of the ball nut and configured to transfer a driving force of a belt; and

support members formed in an inner peripheral surface of the nut pulley and configured to add a supporting force while being elastically transformed when the nut pulley is engaged with the ball nut.

2. The belt type driveline of claim 1, wherein the support member is inserted in and coupled to an inner side of the nut pulley.

3. The belt type driveline of claim 2, wherein the nut pulley includes coupling recesses to which the support members are coupled in the inner peripheral surface thereof.

4. The belt type driveline of claim 1, wherein the support member is integrally formed with the nut pulley by a molding.

5. The belt type driveline of one of claims 2 to 4, wherein the support member includes a protrusion protruding in a radial direction.

6. The belt type driveline of one of claims 2 to 4, wherein the support member is formed to have a curved surface convex to a radial direction.

7. The belt type driveline of claim 1, wherein the support member comprises:

a fixed part inserted in and integrally fixed to the inside of the nut pulley; and

an elastically transformable part protruding outward from the inner peripheral surface of the nut pulley and being elastically transformed.

8. The belt type driveline of claim 7, wherein both side edges connected to the fixed parts extend in a radial direction, are then bent in a circumferential direction, and then connected to each other, so as to form the elastically transformable part.

9. The belt type driveline of claim 8, wherein the elastically transformable part includes a protrusion formed at a region at which the side edges of the elastically transformable part are connected to each other after being bent in the circumferential direction, wherein the protrusion protrudes in the radial direction.

10. The belt type driveline of claim 7, wherein the elastically transformable part is formed to have a curved surface convex to a radial direction.

11. The belt type driveline of claim 7, wherein the support member is integrally formed with the nut pulley by a molding.

12. A rack assist type electric power steering apparatus, comprising:

a torque sensor for outputting an electrical signal proportionate to steering torque;

an Electronic Control Unit (ECU) for generating a control signal based on the electrical signal transferred from the torque sensor;

a motor for generating auxiliary steering power based control signal transferred from the ECU; and

a belt type driveline for transferring auxiliary power generated in the motor to a rack bar,

wherein the belt type driveline comprises;

a ball nut engaged with the rack bar and configured to slide the rack bar;

a nut pulley engaged with an outer peripheral surface of the ball nut and configured to transfer a driving force of a belt; and

support members formed in an inner peripheral surface of the nut pulley and configured to add a supporting force while being elastically transformed when the nut pulley is engaged with the ball nut.