Electromechanical strut with motor-gearbox assembly having dual stage planetary gearbox

Patent metadata

Field	Value
Publication number	US-9776483-B2
Application number	US-201514938156-A
Country	US
Kind code	B2
Filing date	Nov 11, 2015
Priority date	Nov 24, 2014
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

An electromechanical strut is provided for moving a pivotal closure member between an open position and a closed position relative to a motor vehicle body. The electromechanical strut includes a drive mechanism having a motor-gearbox assembly that is operable to drive a rotatable power screw. The drive mechanism converts rotary motion of the power screw into linear motion of an extensible member to move the extensible member between a retracted position corresponding to the closed position of the closure member and an extended position corresponding to the open position of the closure member. The motor-gearbox assembly includes a gearbox unit equipped with a dual-stage planetary geartrain that is operably disposed between a motor output and the power screw. The dual-stage planetary geartrain includes a first stage gearset and a second stage gearset sharing a common ring gear.

First claim

What is claimed:

1. An electromechanical strut for moving a pivotal closure member between an open position and a closed position relative to a motor vehicle body, the electromechanical strut comprising:
a housing connected to one of the closure member and the motor vehicle body;
an extensible member slideably moveable relative to the housing and connected to the other one of the closure member and the motor vehicle body; and
a drive mechanism operable for converting rotary motion of a drive member into linear motion of the extensible member for moving the extensible member between a retracted position relative to the housing which corresponds to the closed position of the closure member and an extended position relative to the housing which corresponds to the open position of the closure member, the drive mechanism including a motor-gearbox assembly having an electric motor unit and a gearbox unit, the electric motor unit having a rotary output member, the gearbox unit having a dual-stage planetary geartrain with an input component coupled to the output member of the electric motor unit and an output component coupled to the drive member, wherein the dual-stage planetary geartrain includes a first stage gearset, a second stage gearset and a common helical ring gear having a first ring gear segment and second ring gear segment which together define a continuous helical gear tooth pattern, and wherein said first stage gearset has a first sun gear with helical gear teeth and which is driven by said output member of said electric motor and further including a plurality of first planet gears, said first planet gears having helical gear teeth that are meshed with said first sun gear and said first ring gear segment of said common helical ring gear and a second stage gearset driven by said first gearset and having a second sun gear with helical gear teeth and a plurality of second planet gears, said second planet gears having helical gear teeth that are meshed with said second sun gear and said second ring segment of said common helical ring gear.

2. The electromechanical strut of claim 1 wherein the first stage gearset includes a first planet carrier, and wherein the plurality of first planet gears are rotatably supported on first pins extending from the first planet carrier.

3. The electromechanical strut of claim 2 wherein the second stage gearset second sun gear is driven by the first planet carrier and wherein the second stage gearset includes a second planet carrier, and wherein the plurality of second planet gears are rotatably supported on second pins associated with the second planet carrier.

4. The electromechanical strut of claim 3 wherein the common helical ring gear is formed in a gearbox chamber of a gearbox housing, and wherein the first and second stage gearsets are disposed within the gearbox chamber.

5. The electromechanical strut of claim 4 wherein the gearbox housing includes a cylindrical segment having an inner diameter surface on which the continuous gear tooth pattern of the common helical ring gear is formed, and a cup-shaped end segment defining a tubular boss having an aperture, and wherein the output component of the dual-stage planetary geartrain is fixed for rotation with the second planet carrier and extends through the aperture in the tubular boss.

6. The electromechanical strut of claim 5 wherein the gearbox unit further includes a spacer ring enclosing an open end of the gearbox housing opposite the cup-shaped end segment, and wherein the spacer ring includes an aperture through which the rotary member of the motor unit extends into the gearbox chamber.

7. The electromechanical strut of claim 4 wherein the first planet gears and the second planet gears are circumferentially aligned along a common axis.

8. The electromechanical strut of claim 7 wherein the first planet gears are identical in size and helical gear tooth configuration to the second planet gears.

9. The electromechanical strut of claim 8 wherein the first sun gear is identical in size and helical gear tooth configuration to the second sun gear.

10. The electromechanical strut of claim 9 wherein the same number of the first planet gears and the second planet gears are associated with the dual-stage planetary geartrain.

11. The electromechanical strut of claim 9 wherein a different number of first planet gears and second planet gears are associated with the dual-stage planetary geartrain.

12. The electromechanical strut of claim 11 wherein a plurality of three of the first planet gears and a plurality of four of the second planet gears are associated with the dual-stage planetary geartrain.

13. The electromechanical strut of claim 4 wherein at least one of the first planet carrier and the second planet carrier is made from plastic.

14. The electromechanical strut of claim 13 wherein the first planet carrier is a two-piece assembly having first and second carrier members interconnected and configured to rotatably support the first planet gears therebetween, and wherein the first and second carrier members are made from plastic.

15. The electromechanical strut of claim 4 wherein the gearbox housing is made from plastic.

16. A gearbox unit for interconnecting a rotary output of a motor unit to a rotary drive component, the gearbox unit comprising:
a gearbox housing defining an internal gearbox chamber and having a stationary common ring gear within the gearbox chamber, the common ring gear having a first ring gear segment and a second ring gear segment which together define a continuous helical gear tooth pattern; and
a dual-stage planetary geartrain disposed within the gearbox chamber and including a first stage gearset associated with the first ring gear segment and which is driven by the rotary output of the motor unit, the first stage gearset including a first sun pear with helical gear teeth and a plurality of first planet gears with helical gear teeth that are meshed with the first sun gear and the first ring gear segment, and a second stage gearset associated with the second ring gear segment, the second stage gearset including a second sun gear with helical gear teeth and a plurality of second planet pears with helical gear teeth that are meshed with the second sun gear and the second ring gear segment, and wherein the second stage gearset is driven by the first stage gearset for driving the rotary drive component at a reduced speed ratio relative to the rotary output of the motor.

17. The gearbox unit of claim 16 wherein the rotary output of the motor unit extends into the gearbox chamber, and wherein the first stage gearset includes the first sun gear drivingly connected to the rotary output of the motor unit, a first planet carrier, and the plurality of first planet gears rotatably supported by the first planet carrier.

18. The gearbox unit of claim 17 wherein the second stage gearset second sun gear is drivingly connected to the first planet carrier, and wherein the second stage gearset includes a second planet carrier, and the plurality of second planet gears rotatably supported by the second planet carrier.

19. The gearbox unit of claim 18 wherein the first planet gears and the second planet gears are circumferentially aligned along a common rotary axis.

20. The gearbox unit of claim 18 wherein the first planet gears are identical in size and in helical tooth configuration to the second planet gears, and wherein the first and second sun gears are identical in size and in helical tooth configuration.

Assignees

• Magna Closures Inc

Inventors

• Shchokin Borys M
• Cosmin Dan
• Scheuring Joseph

Classifications

• E05Y2900/546

  Tailboards, tailgates or sideboards opening upwards · CPC title

• F16H2025/2087

  using planetary gears · CPC title

• B60J5/107 Primary

  constructional details, e.g. about door frame, panels, materials used, reinforcements · CPC title

• E05Y2900/548

  Trunk lids · CPC title

• E05F15/622

  using screw-and-nut mechanisms · CPC title