LINEAR ACTUATOR

• US 20100282009A1
• Filed: 01/12/2009
• Published: 11/11/2010
• Est. Priority Date: 01/12/2008
• Status: Active Grant

• Current Assignee: Linak A/S (Linak Holding A/S)
• Original Assignee: Linak A/S (Linak Holding A/S)
• Inventors: Sørensen, René, Lorenzen, Anders B., Knudsen, Martin Kahr
• Granted Patent: US 8,308,603 B2
• Time in Patent Office: Days
• US Class Current: 74/89.37
• CPC Class Codes: F16H 2025/2031 Actuator casings
• CPC Class Codes: F16H 2025/2084 Perpendicular arrangement of drive motor to screw axis
• CPC Class Codes: F16H 2025/2087 using planetary gears
• CPC Class Codes: F16H 2025/209 using worm gears
• CPC Class Codes: F16H 25/20 Screw mechanisms with automatic reversal F16H25/12
• CPC Class Codes: H02K 7/06 Means for converting reciprocating motion into rotary motion or vice versa
• CPC Class Codes: Y10T 74/18576 including screw and nut
• CPC Class Codes: Y10T 74/18688 Limit stop
• CPC Class Codes: Y10T 74/18704 Means to selectively lock or retard screw or nut

Abstract

A linear actuator comprising a spindle (5) with a spindle nut (6), where the spindle (5) is driven by an electric motor (2) via a transmission (3,4), comprising a planetary gear (4). The construction is constructed in such a way that the spindle (5) is lead through the transmission (3,4) and is embedded by means of a ball bearing (20) in connection with a rear mounting (10), causing the axial forces to be lead through the transmission (3,4) via the spindle (5) and the ball bearing (20) to the rear mounting (10). This means that the construction is simpler and less voluminous and that the axial forces, moreover, are not transferred to the transmission.

Claims

1. A linear actuator comprising:

an electric motor (2),

a gear housing (18),

a transmission comprising a planetary gear (4) with a sun wheel (17), a planetary wheel holder (13) with planetary wheels (14) in mesh with the sun wheel (17) and a tooth rim (15) in the gear housing (18), where the planetary wheels (14) are in mesh with the toothed rim (15);

a spindle (5) in connection with the transmission,

a spindle nut (6) on the spindle,

a bearing (20) for embedding a shaft end of the spindle (5), wherein the shaft end of the spindle (5) is lead freely through the transmission and connected to the bearing (20), and where the connection between the shaft end of the spindle (5) and the transmission allows a mutual axial movement so that axial forces are only lead through the spindle bypassing the transmission and directly to the bearing (20).

2. The linear actuator according to claim 1, including a rear mounting (10) and the bearing (20) is located in the gear housing (18) between the transmission and the rear mounting (10) directly or indirectly.

3. The linear actuator according to claim 1, wherein the connection between the planetary wheel holder (13) and the spindle (5) is an axially displaceable connection secured against rotation constructed so that the planetary wheel holder (13) may be displaced in the longitudinal direction relative to the spindle (5) while the planetary wheel holder (13) and the spindle (5) are mutually secured against rotation.

4. The linear actuator according to claim 1, wherein the sun wheel (17) of the planetary gear is embedded on a shaft end of the spindle (5).

5. The linear actuator according to claim 3, wherein the connection between the planetary wheel holder (13) and the spindle (5) comprises a bushing (12) on the shaft end of the spindle (5), and the shaft end and the bushing (12) over at least part of the length of the bushing (12) have means for mutual securing against rotation, and the bushing (12) moreover has means for securing the planetary wheel holder (13) against rotation relative to the bushing (12).

6. The linear actuator according to claim 3, wherein the bushing (12) forms a stop for movement of the planetary wheel holder (13) in at least one axial direction.

7. The linear actuator according to claim 4, wherein the bushing (12), at least over a distance functions as a slide bearing for the sun wheel (17), embedded on the bushing (12).

8. The linear actuator according to claim 7, wherein the sun wheel (17) is embedded in connection with a wall (18b) in the gear housing (18) and that the bushing (12) is lead through the wall and on the other side of the wall is in connection with an extension (19), connected to the bushing (12) by means of a spline connection, securing the bushing (12) and the extension (19) against mutual rotation.

9. The linear actuator according to claim 8, wherein the bearing (20) is in connection with the extension (19).

10. The linear actuator according to claim 9, wherein a braking device (22) having at least one brake disc (24) is located in connection with the bearing (20) and the rear mounting (10), and performs a braking effect in at least one rotational direction of the spindle (5), and the braking force does not change or noticeable change as the braking disc (24) is worn, as the spindle (5) is axially displaceable in the transmission.

11. The linear actuator according to claim 1, wherein the wall (18a) in the gear housing (18) and the driven gear wheel (17) is constructed so that the wall (18a) functions as a centering and support for the gear wheel (17).

12. The linear actuator according to claim 11, wherein the transmission further comprises a worm gear, where the worm wheel (17a) is interconnected with the sun wheel (17) in the worm gear and the worm wheel (17a) is in mesh with a worm (16) driven by the electric motor (2).

13. The linear actuator according to claim 11, wherein the worm wheel (17a);

on the side facing the transversal wall (18b) in the gear housing (18), is designed with a recess or collar (17b) around its axial center line, which is in connection with a cylindrical counter part (18a) constructed in the transversal wall (18b) in the gear housing (18) or vice versa.

14. The linear actuator according to claim 1, wherein the toothed rim (15) is a separate ring having internal teeth (27) secured against rotation in the gear housing (18).

15. The linear actuator according to claim 14, wherein the mutual means for securing against rotation consist of at least one pin or list (28) on the outside of the separate toothed rim (15) and at least one counter part in the form of one or more axially running guides or tracks (29) on the inner side of the gear housing (18) or vice versa, and has a stop (30) which determines the position of the separate toothed rim (15) in the longitudinal direction of the gear housing (18).