Load compensator for height adjustable table

• US 20070137535A1
• Filed: 05/02/2006
• Published: 06/21/2007
• Est. Priority Date: 12/16/2005
• Status: Abandoned Application

• Current Assignee: Steelcase Incorporated
• Original Assignee: Steelcase Development Corporation (Steelcase Incorporated)
• Inventors: Heidmann, Kurt, Jones, David
• Application Number:
  US11/415,934
• Publication Number:
  US 20070137535A1
• Time in Patent Office: Days
• US Class Current: 108/147
• CPC Class Codes: A47B 9/02 with balancing device, e.g. by springs, by weight

Abstract

A support assembly including a first column having a length dimension parallel to a substantially vertical extension axis, a second column supported by the first member for sliding motion along the extension axis between at least an extended position and a retracted position, a spring that generates a variable spring force that depends at least in part on the degree of spring loading, the spring having first and second ends where the first end is supported by and stationary with respect to the second column, an equalizer assembly including a first end linked to the second end of the spring and a second end linked to the first column, the force equalizer assembly and spring applying a force between the first and second columns tending to drive the columns into the extended position wherein the applied force is substantially constant irrespective of the position of the second column with respect to the first column and one of a locking mechanism, a velocity governing assembly, a roller assembly and a counterbalancing adjustment assembly.

Claims

1. A support assembly, the assembly comprising:

a first elongated member having a length dimension parallel to a substantially vertical extension axis;

a second elongated member supported by the first member for sliding motion along the extension axis between at least an extended position and a retracted position;

a spring that generates a variable spring force that depends at least in part on the degree of spring loading, the spring having first and second ends where the first end is supported by and stationary with respect to the second elongated member; and

a velocity governor supported by at least one of the first and second elongated members for restricting the speed with which the second elongated member moves with respect to the first elongated member along the extension axis.

2. The assembly of claim 1 wherein the first elongated member includes a length dimension along the extension axis and wherein the velocity governor further includes a threaded shaft linked to and stationary with respect to the first elongated member and aligned substantially along the extension axis, a brake member forming a braking surface proximate the threaded shaft, a nut supported by the threaded shaft for movement there along and coupled to the second member, at least one brake shoe supported by the nut proximate the braking surface for sliding motion away from the threaded shaft and toward the braking surface and a biaser for biasing the brake shoe toward the threaded shaft and away from the braking surface, wherein, when the nut rotates about the shaft, centrifugal force on the brake shoe causes the brake shoe to move toward the braking surface and, when the centrifugal force exceeds a threshold level, the shoe contacts the braking surface.

3. The assembly of claim 2 wherein the brake member includes a housing mounted to the second elongated member for movement therewith.

4. The assembly of claim 2 wherein the braking surface includes an annular surface and wherein the brake shoe includes an arced surface that mirrors the annular surface and that contacts the annular surface when the threshold level is exceeded.

5. The assembly of claim 4 further including second and third brake shoes supported by the nut proximate the braking surface for sliding motion away from the threaded shaft and toward the braking surface and wherein the first, second and third brake shoes are substantially circumferentially equi-spaced about the nut for sliding motion away from the shaft in different directions.

6. The assembly of claim 5 wherein the nut includes an annular recess about an external surface and wherein the brake shoes are at least in part receivable within the annular recess.

7. The assembly of claim 6 wherein the nut further forms a rib extending along a trajectory perpendicular to the shaft for each of the brake shoes and wherein each brake shoe includes a groove that receives the rib to guide the shoe during sliding motion.

8. The assembly of claim 7 wherein the biaser includes a loop shaped extension spring.

9. The assembly of claim 8 wherein each of the brake shoes forms a channel substantially along a length dimension and wherein the extension spring is received within each of the brake shoe channels and generally around a lateral surface of the nut.

10. The assembly of claim 2 wherein the nut forms one of a rib and a groove extending along a trajectory perpendicular to the shaft and wherein the brake shoe forms the other of a rib and a groove that receives the one of the rib and groove formed by the nut to guide the shoe during sliding motion.

11. The assembly of claim 6 wherein the biaser includes a loop shaped extension spring.

12. The assembly of claim 3 wherein the housing includes a housing structure that forms a space, the nut is supported within the space, the assembly further including first and second bearing rings and wherein the bearing rings couple the nut to the housing.

13. The assembly of claim 12 wherein the housing includes an annular surface that forms the braking surface and wherein the brake shoe forms an arced surface that mirrors the braking surface such that, when the threshold force is exceeded, the arced surface contacts the braking surface.

14. The assembly of claim 2 further including a table top supported by one of the first and second members.

15. The assembly of claim 14 wherein the spring tends to drive the second elongated member and table top upward.

16. The assembly of claim 2 wherein the spring is a coil compression spring.

17. The assembly of claim 1 further including an equalizer assembly including a first end linked to the second end of the spring and a second end linked to the first member, the force equalizer assembly and spring applying a force between the first and second members tending to drive the elongated members into the extended position wherein the applied force is substantially constant irrespective of the position of the second elongated member with respect to the first elongated member.

18. The assembly of claim 17 wherein the equalizer includes a strand and a cam pulley, the cam pulley mounted to the second member for rotation about a pulley axis substantially perpendicular to the vertical extension axis, a first end of the strand linked to the second end of the spring, a second end of the strand linked to the first member and a central section of the strand wrapped around the cam pulley.

19. The assembly of claim 18 wherein the pulley includes a lateral surface spaced from the pulley axis, the lateral surface forming a helical cable channel that wraps around the pulley axis and that includes first and second channel ends so that at least a portion of the channel and the pulley axis forms channel radii perpendicular to the pulley axis, the radii increasing along at least a portion of the channel in the direction from the first channel end toward the second channel end, the central section of the strand received within at least a portion of the pulley channel with the first and second strand ends extending from a first radii portion and a second radii portion of the channel where the first portion has a radii that is smaller than the second portion.

20. The assembly of claim 19 wherein the first radii portion is at least 0.5 inches irrespective of the relative positions of the first and second columns.

21. The assembly of claim 20 wherein the first radii portion is approximately 0.5 inches when the second column is in the extended position and is approximately 2.0 inches when the second column is in the retracted position.

22. The assembly of claim 2 wherein the spring is a linear spring.

23. A telescoping assembly, the assembly comprising:

a first member having a length dimension along an extension axis;

a second member supported by the first member for movement along the extension axis;

a threaded shaft linked to and stationary with respect to the first member and aligned substantially along the extension axis;

a brake member forming a braking surface proximate the threaded shaft;

a nut supported by the threaded shaft for movement there along and coupled to the second member;

at least one brake shoe supported by the nut proximate the braking surface for sliding motion away from the threaded shaft and toward the braking surface;

a biaser for biasing the brake shoe toward the threaded shaft and away from the braking surface;

wherein, when the nut rotates about the shaft, centrifugal force on the brake shoe causes the brake shoe to move toward the braking surface and, when the centrifugal force exceeds a threshold level, the shoe contacts the braking surface.

24. The assembly of claim 23 wherein the brake member includes a housing mounted to the second member for movement therewith.

25. The assembly of claim 23 wherein the braking surface includes an annular surface and wherein the brake shoe includes an arced surface that mirrors the annular surface and contacts the annular surface when the threshold level is exceeded.

26. The assembly of claim 25 further including second and third brake shoes supported by the nut proximate the braking surface for sliding motion away from the threaded shaft and toward the braking surface and wherein the first, second and third brake shoes are substantially circumferentially equi-spaced about the nut for sliding motion away from the shaft in different directions.

27. The assembly of claim 26 wherein the nut includes an annular recess about an external surface and wherein the brake shoes are at least in part receivable within the annular recess.

28. The assembly of claim 27 wherein the nut further forms a rib extending along a trajectory perpendicular to the shaft for each of the brake shoes and wherein each brake shoe includes a groove that receives the rib to guide the shoe during sliding motion.

29. The assembly of claim 28 wherein the biaser includes a loop shaped extension spring.

30. The assembly of claim 29 wherein each of the brake shoes forms a channel substantially along a length dimension and wherein the extension spring is received within each of the brake shoe channels and generally around a lateral surface of the nut.

31. The assembly of claim 23 wherein the nut forms one of a rib and a groove extending along a trajectory perpendicular to the shaft and wherein the brake shoe forms the other of a rib and a groove that receives the one of the rib and groove formed by the nut to guide the shoe during sliding motion.

32. The assembly of claim 26 wherein the biaser includes a loop shaped extension spring.

33. The assembly of claim 24 wherein the housing includes a housing structure that forms a space, the nut is supported within the space, the assembly further including first and second bearing rings and wherein the bearing rings couple the nut to the housing.

34. The assembly of claim 33 wherein the housing includes an annular surface that forms the braking surface and wherein the brake shoe forms an arced surface that mirrors the braking surface such that, when the threshold force is exceeded, the arced surface contacts the braking surface.

35. The assembly of claim 23 further including a table top supported by one of the first and second members.

36. A support assembly, the assembly comprising:

a first elongated member having a length dimension parallel to a substantially vertical extension axis;

a second elongated member supported by the first member for sliding motion along the extension axis between at least an extended position and a retracted position;

a spring that generates a variable spring force that depends at least in part on the degree of spring loading, the spring having first and second ends where the first end is supported by and stationary with respect to the second elongated member;

an equalizer assembly including a first end linked to the second end of the spring and a second end linked to the first member, the force equalizer assembly and spring applying a force between the first and second members tending to drive the elongated members into the extended position wherein the applied force is substantially constant irrespective of the position of the second elongated member with respect to the first elongated member; and

a velocity governor supported by at least one of the first and second elongated members for restricting the speed with which the second elongated member moves with respect to the first elongated member along the extension axis.

37. The assembly of claim 36 wherein the first elongated member includes a length dimension along the extension axis and wherein the velocity governor further includes a threaded shaft linked to and stationary with respect to the first elongated member and aligned substantially along the extension axis, a brake member forming a braking surface proximate the threaded shaft, a nut supported by the threaded shaft for movement there along and coupled to the second member, at least one brake shoe supported by the nut proximate the braking surface for sliding motion away from the threaded shaft and toward the braking surface and a biaser for biasing the brake shoe toward the threaded shaft and away from the braking surface, wherein, when the nut rotates about the shaft, centrifugal force on the brake shoe causes the brake shoe to move toward the braking surface and, when the centrifugal force exceeds a threshold level, the shoe contacts the braking surface.

38. The assembly of claim 37 wherein the brake member includes a housing mounted to the second elongated member for movement therewith.

39. The assembly of claim 37 wherein the braking surface includes an annular surface and wherein the brake shoe includes an arced surface that mirrors the annular surface and that contacts the annular surface when the threshold level is exceeded.

40. The assembly of claim 39 further including second and third brake shoes supported by the nut proximate the braking surface for sliding motion away from the threaded shaft and toward the braking surface and wherein the first, second and third brake shoes are substantially circumferentially equi-spaced about the nut for sliding motion away from the shaft in different directions.

41. The assembly of claim 40 wherein the nut includes an annular recess about an external surface and wherein the brake shoes are at least in part receivable within the annular recess.

42. The assembly of claim 37 wherein the biaser includes a loop shaped extension spring.

43. The assembly of claim 37 wherein the nut forms one of a rib and a groove extending along a trajectory perpendicular to the shaft and wherein the brake shoe forms the other of a rib and a groove that receives the one of the rib and groove formed by the nut to guide the shoe during sliding motion.

44. The assembly of claim 36 further including a table top supported by one of the first and second members.

45. The assembly of claim 37 wherein the equalizer includes a strand and a cam pulley, the cam pulley mounted to the second member for rotation about a pulley axis substantially perpendicular to the vertical extension axis, a first end of the strand linked to the second end of the spring, a second end of the strand linked to the first member and a central section of the strand wrapped around the cam pulley.