ELECTROMECHANICAL STRUT

• US 20090200830A1
• Filed: 03/16/2009
• Published: 08/13/2009
• Est. Priority Date: 08/06/2004
• Status: Active Grant

• Current Assignee: Magna Closures Company Limited (Magna International Incorporated)
• Original Assignee: Magna Closures Company Limited (Magna International Incorporated)
• Inventors: Mitchell, Stephen A.G., PATON, Gordon Andrew, Mrkovic, Dragan, Groszkowski, Krzysztof, Gusev, Victor, Shchokin, Borys M.
• Granted Patent: US 7,938,473 B2
• Time in Patent Office: Days
• US Class Current: 296/146.800
• CPC Class Codes: B60J 5/101 for non-load transporting vehicles, i.e. family cars including vans
• CPC Class Codes: E05F 1/1058 for counterbalancing
• CPC Class Codes: E05F 1/1083 with a leaf or similar spring E05F1/1284 takes precedence
• CPC Class Codes: E05F 15/622 using screw-and-nut mechanisms
• CPC Class Codes: E05Y 2201/434 Electromotors; Details thereof
• CPC Class Codes: E05Y 2201/47 Springs; Spring tensioners
• CPC Class Codes: E05Y 2201/604 Transmission members
• CPC Class Codes: E05Y 2201/706 Shafts
• CPC Class Codes: E05Y 2201/72 Planetary gearing
• CPC Class Codes: E05Y 2400/502 of components
• CPC Class Codes: E05Y 2600/13 by motors, magnets, springs, weights
• CPC Class Codes: E05Y 2800/11 Manual wing operation
• CPC Class Codes: E05Y 2800/122 Telescopic action
• CPC Class Codes: E05Y 2800/232 of motors and transmissions
• CPC Class Codes: E05Y 2800/238 of springs and transmissions
• CPC Class Codes: E05Y 2800/678 Elastomers
• CPC Class Codes: E05Y 2900/546 Tailgates
• CPC Class Codes: E05Y 2900/548 Trunk lids
• CPC Class Codes: Y10T 74/18664 Shaft moves through rotary drive means

Abstract

An electromechanical strut is provided for moving a pivotal lift gate between an open position and a closed position relative to a motor vehicle body. The electromechanical strut includes a housing connected to one of the lift gate and the motor vehicle body. An extensible shaft is slidably mounted to the housing. The extensible shaft is connected to the other of the lift gate and the motor vehicle body. A drive mechanism includes a rotatable power screw. The drive mechanism converts rotary motion of the power screw into linear motion of the extensible shaft to move the extensible shaft between a retracted position corresponding to the closed position of the lift gate and an extended position corresponding to the open position of the lift gate. A power spring includes one end connected to the extensible shaft and another end connected to the housing for providing a mechanical counterbalance to the weight of the lift gate.

Claims

1. An electromechanical strut for moving a pivotal lift gate 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 lift gate and the motor vehicle body;

an extensible member slidably mounted to the housing, the extensible member connected to the other of the lift gate and the motor vehicle body;

a drive mechanism including a power screw which rotates in situ, the drive mechanism converting rotary motion of the power screw into linear motion of the extensible member to move the extensible member between a retracted position corresponding to the closed position of the lift gate and an extended position corresponding to the open position of the lift gate; and

a power spring coupled between the extensible member and the housing for providing a mechanical counterbalance to the weight of the lift gate.

2. An electromechanical strut as set forth in claim 1 wherein the drive mechanism includes a motor-gear assembly mounted in the housing and operably coupled to the power screw, the screw extending into the extensible member.

3. An electromechanical strut as set forth in claim 2 including a drive nut fixedly secured to the extensible member and threadedly engaging the power screw.

4. An electromechanical strut as set forth in claim 3 wherein the extensible member includes an outer cylindrical wall and an radially inner cylindrical wall dividing the interior of the extensible member into an outer toroidal chamber and a radially interior chamber, the power spring being received within the outer toroidal chamber and the power screw being received within the radially inner interior chamber.

5. An electromechanical strut as set forth in claim 4 wherein the housing includes a stationary guide tube extending into the outer toroidal chamber of the extensible member adjacent to the radially inner cylindrical wall thereof such that a radially inner edge of the power spring is guided by the stationary guide tube and a radially outer edge of the power spring is guided by the outer cylindrical wall of the extensible member.

6. An electromechanical strut as set forth in claim 5 wherein the power spring comprises two serially arranged coils segments with a thrust bearing therebetween, the coil spring segments uncoiling and recoiling as the extensible member moves relative to the housing.

7. An electromechanical strut for moving a pivotal lift gate 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 lift gate and the motor vehicle body, the housing including a stationary guide tube;

an extensible member slidably mounted to the housing and connected to the other of the lift gate and the motor vehicle body, the extensible member including spaced apart outer and inner tubular walls defining a toroidal chamber therebetween and a radially inner interior chamber, the stationary guide tube extending into the toroidal chamber adjacent the inner tubular wall of the extensible member;

at least one coil spring disposed within the toroidal chamber and coupled between one end of the extensible member and the housing for providing a mechanical counterbalance to the weight of the lift gate, wherein a radially inner edge of the at least one coil spring is guided by the stationary guide tube and a radially outer edge of the at least one coil spring is guided by the outer tubular wall of the extensible member;

a motor-gear assembly mounted in the housing;

a rotatable power screw connected to and driven by the motor gear assembly, the power screw extending into the radially interior chamber of the extensible member; and

a drive nut fixedly mounted in the interior chamber of the extensible member, the drive nut threadingly engaging the power screw;

whereby the motor gear assembly converts rotary motion of the power screw into linear motion of the extensible member to move the extensible member between a retracted position corresponding to the closed position of the lift gate and an extended position corresponding to the open position of the lift gate.

8. An electromechanical strut for moving a pivotal lift gate between an open position and a closed position relative to a motor vehicle body, the electromechanical strut comprising:

a power unit, the power unit including a casing and a motor-gear assembly mounted within the casing, the motor-gear assembly including an output drive shaft; and

a telescoping unit, the telescoping unit including a stationary guide tube and an extensible member slidably mounted to the stationary guide tube;

the stationary member including a rotatable power screw journalled therein;

the extensible member including spaced apart outer and inner tubular walls defining a toroidal chamber therebetween and a radially inner interior chamber, the stationary guide tube extending into the toroidal chamber adjacent the inner tubular wall of the extensible member;

the toroidal chamber receiving at least one coil spring connected between one end of the extensible member and one end of the stationary tube, wherein a radially inner edge of the at least one coil spring is guided by the stationary guide tube and a radially outer edge of the at least one coil spring is guided by the outer tubular wall of the extensible member; and

the radially inner interior chamber having a drive nut fixedly mounted therein, the drive nut threadingly engaging the power screw;

wherein the telescopic unit is attached to the power unit such that the output drive shaft drivingly engages the power screw.

9. An electromechanical strut as set forth in claim 8 including an elastomeric coupling mounted between power unit and the telescoping unit for reducing impact of the motor-gear assembly on the telescoping unit.

10. An electromechanical strut as set forth in claim 9 wherein the elastomeric coupling features a plurality of lugs and is mounted to one of the stationary guide tube and the power unit casing, and at least one of the stationary guide tube and the power unit casing features lugs interdigitating with the coupling lugs.

11. An electromechanical strut as set forth in claim 8, further including one or more elastomeric spacers mounted between the motor gear assembly and the power unit casing.

12. An electromechanical strut as set forth in claim 8, including a gearbox coupler mounted to power screw for readily interconnecting the power screw with the power unit output shaft.

13. An electromechanical strut as set forth in claim 8, wherein two serially arranged coils segments with a thrust bearing therebetween are mounted in the toroidal chamber, one coil spring being wound in a first direction, the other coil spring being wound in the other direction.

14. An electromechanical strut for moving a pivotal lift gate between an open position and a closed position relative to a motor vehicle body, the electromechanical strut comprising:

a power unit, the power unit including a casing and a motor-gear assembly mounted within the casing, the motor-gear assembly including an output drive shaft; and

a telescoping unit, the telescoping unit including a stationary tube and an extensible member slidably mounted to the stationary tube;

the stationary tube including a rotatable power screw journalled therein;

the telescoping unit including one coil spring connected between one end of the extensible member and one end of the stationary tube, the extensible member having a drive nut threadingly engaging the power screw;

wherein the telescopic unit is attached to the power unit such that the output drive shaft drivingly engages the power screw; and

an elastomeric coupling mounted between power unit and the telescoping unit for reducing impact of the motor-gear assembly on the telescoping unit.

15. An electromechanical strut as set forth in claim 14, wherein the elastomeric coupling features a plurality of lugs and is mounted to one of the stationary guide tube and the power unit casing, and at least one of the stationary guide tube and the power unit casing features lugs interdigitating with the coupling lugs.

16. An electromechanical strut as set forth in claim 15, including a gearbox coupler mounted to power screw for readily interconnecting the power screw with the power unit output shaft.

18. An electromechanical strut as set forth in claim 14, wherein two serially arranged coils segments with a thrust bearing therebetween are mounted in the toroidal chamber, one coil spring being wound in a first direction, the other coil spring being wound in the other direction.