Telescopic actuator

• US 7,225,694 B2
• Filed: 02/05/2004
• Issued: 06/05/2007
• Est. Priority Date: 03/03/2003
• Status: Expired due to Fees

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Said, Brian R.
• Primary Examiner(s): FENSTERMACHER, DAVID MORGAN
• Application Number:
  US10/771,716
• Publication Number:
  US 20040173041A1
• Time in Patent Office: 1,216 Days
• Field of Search: 74/893.5, 74/893.7, 74/893.8, 74/893.9
• US Class Current: 74/89.35
• CPC Class Codes: F16H 25/20 Screw mechanisms with automatic reversal F16H25/12
• CPC Class Codes: F16H 25/2056 Telescopic screws with at least three screw members in coaxial arrangement
• CPC Class Codes: Y10T 74/18672 Plural screws in series [e.g., telescoping, etc.]
• CPC Class Codes: Y10T 74/18688 Limit stop

Abstract

A telescopic actuator has a lead screw and one or more concentric or tiered screws. Each screw has one or more tangential interference stop features such as stop cogs. As the lead screw is rotated, it translates out of the concentric screws. As the lead screw reaches its maximum extension, a tangential interference stop feature on the lead screw tangentially contacts a tangential interference stop feature on the concentric screw with which the lead screw is threadably engaged. Upon tangential contact, the associated concentric screw rotates in unison with the lead screw. When there are additional concentric screws, as each concentric screw reaches its maximum extension, the system of tangential contacting of tangential interference stop features causes the other concentric screws to extend out in sequential fashion.

Claims

1. A telescoping actuator comprising:

a lead screw;

a lead interference stop feature radially attached to said lead screw;

a first tubular screw, said first tubular screw having inner threads; and

a first interference stop feature radially attached to said inner threads of said first tubular screw;

wherein said lead screw is threadably engaged to said first tubular screw;

wherein upon rotation of said lead screw, said lead screw translates out from said first tubular screw;

and further wherein said lead interference stop feature tangentially contacts said first interference stop feature, and further wherein upon contact of said lead interference stop feature and said first interference stop feature, said first tubular screw rotates in unison with said lead screw.

2. The telescoping actuator according to claim 1, further comprising a housing to enclose said actuator, said housing comprising a first and second segment, wherein said first segment and said second segment further comprise longitudinal limit stops, and wherein said first segment is rotatably keyed to said second segment, and further wherein said first segment of said housing translates relative to said second segment of said housing within said longitudinal limit stops, thereby preserving a limited portion of overlapping sleeved engagement between said first segment and said second segment.

3. The telescoping actuator according to claim 1, further comprising:

a second tubular screw, said second tubular screw comprising inner threads;

wherein said first tubular screw further comprises outer threads;

a second tangential interference stop feature, said second tangential interference stop feature attached to said outer threads of said first tubular screw; and

a third tangential interference stop feature, said third tangential interference stop feature attached to said inner threads of said second tubular screw;

wherein said outer threads of said first tubular screw are threadably engaged with said inner threads of said second tubular screw;

and further wherein said second tangential interference stop feature tangentially contacts said third tangential interference stop feature, thereby causing said second tubular screw to rotate in unison with said lead screw and said first tubular screw.

4. The telescoping actuator according to claim 1, wherein said telescoping actuator comprises a linear drive actuator converting rotary motion to linear motion.

5. The telescoping actuator according to claim 4, wherein said linear drive actuator comprises an antenna.

6. The telescoping actuator according to claim 1, wherein said telescoping actuator comprises a surgical device.

7. The telescoping actuator according to claim 1, wherein said threads of said lead screw extend along said lead screw for a distance that is less than the length of said lead screw.

8. The telescoping actuator according to claim 1, wherein said inner threads of said first tubular screw extend along said first tubular screw for a distance that is less than the length of said first tubular screw.

9. The telescoping actuator according to claim 1, wherein said lead tangential interference stop feature is positioned on said lead screw so that said lead screw does not translate substantially completely out of said first tubular screw.

10. The telescoping actuator according to claim 1, further comprising a grounding bracket coupled to said lead screw.

11. A telescoping actuator comprising:

a lead tubular screw, said lead tubular screw comprising inner threads;

a lead interference stop feature radially attached to said lead tubular screw;

a second tubular screw, said second tubular screw comprising outer threads; and

a first interference stop feature radially attached to said outer threads of said second tubular screw;

wherein said lead tubular screw is threadably engaged to said second tubular screw;

wherein upon rotation of said lead tubular screw, said lead tubular screw translates out from said second tubular screw;

and further wherein said lead interference stop feature tangentially contacts said first interference stop feature, and further wherein upon contact of said lead interference stop feature and said first interference stop feature, said second tubular screw rotates in unison with said lead tubular screw.

12. The telescoping actuator according to claim 11, further comprising a housing to enclose said actuator, said housing comprising a first and second segment, said first and second segment comprising longitudinal limit stops, wherein said first segment is rotatably keyed to said second segment, and further wherein said first segment of said housing translates relative to said second segment of said housing within said longitudinal limit stops, thereby preserving a limited portion of overlapping sleeved engagement between said first segment and said second segment.

13. The telescoping actuator according to claim 11, further comprising:

a third tubular screw, said third tubular screw comprising outer threads;

wherein

said second tubular screw further comprises inner threads;

a second tangential interference stop feature, said second tangential interference stop feature attached to said inner threads of said second tubular screw; and

a third tangential interference stop feature, said third tangential interference stop feature attached to said outer threads of said third tubular screw;

wherein said inner threads of said second tubular screw arc threadably engaged with said outer threads of said third tubular screw;

and further wherein said second tangential interference stop feature tangentially contacts said third tangential interference stop feature, thereby causing said third tubular screw to rotate in unison with said lead tubular screw and said second tubular screw.

14. The telescoping actuator according to claim 11, wherein said telescoping actuator comprises a linear drive actuator convening rotary motion to linear motion.

15. The telescoping actuator according to claim 14, wherein said linear drive actuator comprises an antenna.

16. The telescoping actuator according to claim 11, wherein said telescoping actuator comprises a surgical device.

17. The telescoping actuator according to claim 11, wherein said threads of said lead tubular screw extend along said lead tubular screw for a distance that is less than the length of said lead tubular screw.

18. The telescoping actuator according to claim 11, wherein said outer threads of said second tubular screw extend along said second tubular screw for a distance that is less than the length of said second tubular screw.

19. The telescoping actuator according to claim 11, wherein said lead tangential interference stop feature is positioned on said lead tubular screw so that said lead tubular screw does not translate substantially completely off of said second tubular screw.

20. A telescoping actuator comprising:

a lead screw;

one or more concentric screws; and

one or more interference stop features;

wherein rotation of said lead screw causes said lead screw to translate out of or off of said concentric screws, said extension occurring until a first interference stop feature radially positioned on said lead screw tangentially contacts a second interference stop feature radially positioned on a first concentric screw; and

wherein upon said tangential contact of said first interference stop feature and said second interference stop feature, further rotation of said lead screw causes said first concentric screw to rotate in unison with said lead screw, thereby forming a tier between said lead screw and said first concentric screw.

21. A telescopic actuator comprising:

a lead screw;

a lead interference stop feature radially attached to said lead screw;

a first screw; and

a first interference stop feature radially attached to said first screw;

wherein said lead screw is threadably engaged to said first screw;

wherein upon rotation of said lead screw, said lead screw translates away from said first screw;

and further wherein said lead interference stop feature tangentially contacts said first interference stop feature, and further wherein upon tangential contact of said lead interference stop feature and said first interference stop feature, said first screw rotates in unison with said lead screw.