Drive for an adjustment device with a worm wheel having a globoid toothing with a cylindrical section

• US 20050269478A1
• Filed: 03/15/2005
• Published: 12/08/2005
• Est. Priority Date: 03/16/2004
• Status: Active Grant

• Current Assignee: IMS Gear SE & Co. KGaA
• Original Assignee: IMS Gear GmbH
• Inventors: Woehrle, Michael, Voeckt, Andreas
• Granted Patent: US 8,904,895 B2
• Time in Patent Office: Days
• US Class Current: 248/430
• CPC Class Codes: F16H 1/16 comprising worm and worm-wheel
• CPC Class Codes: Y10T 74/19828 Worm
• CPC Class Codes: Y10T 74/19949 Teeth
• CPC Class Codes: Y10T 74/19953 Worm and helical

Abstract

Drive for an adjustment device, comprising a worm wheel which has a globoid toothing with a central cylindrical section. The drive for an adjustment device, specifically, a seat adjustment device within a vehicle, has a spindle (5) and a gear mechanism (9) coupled thereto which has a drive worm (20) drivable by a motor (2). The drive worm (20) engages a worm wheel (40). The toothing of the worm wheel (40) has a central section with cylindrical toothing (Z), which section transitions on both sides into a globoid toothing (G) such that at least one complete annular surface remains on both ends of the worm wheel (40). A method according to the invention of fabricating this worm wheel provides for a cutter (60) which is moved vertically relative to the axis (A) of a worm wheel blank. Advantages: Elimination of thrust washers; improved acoustics, torque fluctuations and vibrations; simple fabrication; improved run-out of the end faces; bearing surfaces projecting beyond the addendum circle of the toothing possible; no ridging on the functional surfaces and thus elimination of a separate deburring procedure.

Claims

1. Drive for an adjustment device within a vehicle, comprising a spindle (5) which is attached to one of two elements (3, 4) that are adjustable relative to each other, and comprising a gear mechanism (9) drivable by a motor (2), which gear mechanism is located on the second element (4), wherein the gear mechanism (9) has a drive worm (20) drivable by the motor (2), the drive worm engaging a worm wheel (40) coupled to the spindle (5), where the toothing of the worm wheel (40) has, as viewed in the axial direction of the worm wheel (9), a circumferential section with cylindrical toothing (z), which section transitions on both sides into a globoid toothing (g) such that at least one complete annular surface (f) remains on both ends of the worm wheel (40).

2. Drive according to claim 1, where the section with the cylindrical toothing is centered relative to the longitudinal axis of the worm wheel.

3. Drive according to claims 1, where the worm wheel (9) has the cylindrical toothing (Z) and bordering globoid toothing (G) in the form of toothing grooves oriented obliquely to the axis (A) of the worm wheel (9).

4. Drive according to claims 1, where the annular surface (F) on the ends of the worm wheel (40) extends to the outer diameter of the worm wheel (40).

5. Drive according to claim 1, where the complete annular surface (F) on the ends of the worm wheel (40) has a height which lies between the tooth root (45) and tooth crown (43) of the toothing of the worm wheel (40).

6. Drive according to claim 1, where the annular surface (F) on the ends of the worm wheel (40) is at least approximately as large as the bearing bushings (14a) of a housing (14) accommodating the gear mechanism (9).

7. Drive according to claim 1, where the cylindrical toothing (Z), as viewed in the axial direction of the worm wheel (40), extends axially over preferably the sum of the axial play, twice the axial misalignment, and twice the expected wear of the individual parts.

8. Drive according to claim 1, where the tooth crown (43) is depressed in the region of the cylindrical toothing (Z)—

relative to the axis (A) of the worm wheel (40)—

as compared to the tooth crown (43) in the region of the globoid toothing (G) of the worm wheel (40).

9. Drive according to claim 1, where the tooth bottom land in the tooth spaces (45) has a central straight section from which circular-arc sections extend on both sides.

10. Drive according to claim 1 where the worm wheel (40) has an internal thread (47) which engages the spindle (5).

11. Drive according to claim 1 where the spindle (5) is fixed and the worm wheel (40) is located rotatably on the spindle (5).

12. Drive according to claim 1, where the worm wheel (40) is in the form of a milled metal part.

13. Drive according to claim 1, where the worm wheel (40) has on both ends annular projections (41) formed as integrated components of the worm.

14. Drive according to claim 1, where the adjustment device is a seat adjustment device for a motor vehicle.

15. Method of fabricating a worm wheel (40), comprising:

a) providing a worm wheel blank;

b) providing a rotating hobbing cutter (60) which is obliquely offset by a predetermined angle relative to an axis (A) of the worm wheel blank;

c) vertically inserting the cutter (60) orthogonally relative to the axis (A) into the worm wheel blank by a specified depth, and longitudinal movement of the cutter (60) by a specified travel (L) to obtain a tooth space (45) of the toothing;

d) removing of the cutter (60) from the generated tooth space (45).

16. Method according to claim 15, angle α

is between approximately 5° and

20°

.

17. Method according to claim 16, where the specified travel (L) is between approximately 0.5 mm and approximately 2 mM.

18. Method according to claim 17, where a hobbing cutter is employed as the cutter (60).