Load compensator for height adjustable table

• US 20060130714A1
• Filed: 12/16/2005
• Published: 06/22/2006
• Est. Priority Date: 12/17/2004
• Status: Active Grant

• Current Assignee: Steelcase Incorporated
• Original Assignee: Steelcase Development Corporation (Steelcase Incorporated)
• Inventors: Heidmann, Kurt, Andres, Todd, Jones, David K.
• Granted Patent: US 7,658,359 B2
• Time in Patent Office: Days
• US Class Current: 108/106
• CPC Class Codes: A47B 13/023 with a central column
• CPC Class Codes: A47B 2013/024 being assembled to a base
• CPC Class Codes: A47B 2200/0051 Telescopic
• CPC Class Codes: A47B 2200/0052 with two telescopic parts
• CPC Class Codes: A47B 9/00 Tables with tops of variable height lecterns with variable height A47B19/06; school forms or desks with variable height A47B39/02, A47B41/02; seats with variable height A47C3/20
• CPC Class Codes: A47B 9/02 with balancing device, e.g. by springs, by weight
• CPC Class Codes: A47B 9/12 with flexible height-adjusting means, e.g. rope, chain
• CPC Class Codes: A47B 9/20 Telescopic guides

Abstract

A force adjustment assembly for use within a telescoping subassembly that includes a first elongated member and a second elongated member that is supported by the first elongated member for sliding motion along an extension axis, the subassembly further including a force equalizer assembly that includes a strand having first and second ends that are supported by the second and first elongated members, respectively, the adjustment assembly comprising a preloader supported by at least one of the first and second elongated members and supporting at least a portion of the strand, the preloader applying a preload force via the strand when the second elongated member is in a fully extended position and an adjuster for adjusting the preload force applied by the preloader.

Claims

1. A telescoping assembly, the assembly comprising:

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

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

a nut mounted to the threaded shaft for movement there along;

a locking member moveable between a locking position and an unlocking position for restricting and allowing rotation of the nut with respect to the threaded shaft, and

a second member supported by the first member for movement along the extension axis, the second member also supported by the nut for movement therewith.

2. The assembly of claim 1 wherein the nut forms a first engaging surface adjacent one end thereof and the locking member forms a second engaging surface proximate the first engaging surface, the second engaging surface contacting the first engaging surface when restricting nut rotation.

3. The assembly of claim 2 wherein the first engaging surface is frusto-conically shaped and circumscribes the shaft.

4. The assembly of claim 3 wherein the second engaging surface is frusto-conically shaped and circumscribes the shaft and wherein the locking member is axially aligned with the shaft and the locking member moves along a trajectory that is substantially parallel to the shaft between the locking position wherein the second engaging surface engages the first engaging surface and the unlocking position wherein the second engaging surface is separated from the first engaging surface.

5. The assembly of claim 4 further including a biasing spring that biases the locking member toward the nut and the second engaging surface toward the first engaging surface.

6. The assembly of claim 5 further including a housing member that forms a cavity and that is supported by the second member for movement therewith, the locking member supported by the housing member for movement between the locking and the unlocking positions.

7. The assembly of claim 5 further including an activation mechanism that is mechanically linked to the locking member for moving the locking member from the locking position toward the unlocking position against the biasing force of the spring.

8. The assembly of claim 1 further including a housing and at least a first mount that mounts the housing to the second member, the nut and the locking member supported by the housing.

9. The assembly of claim 8 wherein the mount is a resilient mount that mechanically isolates the housing and components supported thereby from the second member.

10. The assembly of claim 9 wherein the housing forms openings on opposite sides of the nut that that shaft extends through, the assembly further including first and second annular guides that mechanically isolate the housing from the shaft.

11. The assembly of claim 10 wherein each of the guides is formed of a low friction material.

12. The assembly of claim 11 wherein each of the guides is formed of urethane.

13. The assembly of claim 9 wherein the mount is a rubber mount.

14. The assembly of claim 13 wherein the mount includes a pair of rubber washers.

15. The assembly of claim 9 including at least three mounts that mechanically isolate the housing components supported thereby from the second member.

16. The assembly of claim 1 further including a housing and first and second bearing races, the housing supported by the second member, the races isolating the nut from the housing, the locking member supported by the housing adjacent the nut.

17. The assembly of claim 2 wherein each of the first and second engaging surfaces are formed of high friction material.

18. The assembly of claim 13 wherein the nut includes first and second nut members, the first nut member forming a threaded opening for receiving the shaft and the second nut member forming an opening that is aligned with the threaded opening and that passes the shaft, the first nut member formed of a low friction material and the second nut member formed of a relatively high friction material.

19. The assembly of claim 1 wherein the nut includes a substantially cylindrical external surface.

20. The assembly of claim 19 wherein the locking member is a primary locking member and wherein the primary locking member restricts rotation of the nut by contacting the cylindrical external surface of the nut.

21. The assembly of claim 20 further including a secondary locking means for, with the primary locking member restricting rotation of the nut, additionally restricting the nut when a force within a first range is applied to the second member along a first trajectory tending to move the second member in a first direction along the extension axis.

22. The assembly of claim 21 further including a third locking means for, with the primary locking member restricting rotation of the nut, additionally restricting the nut when a force within a second range is applied to the second member along a second trajectory tending to move the second member in a second direction along the extension axis where the second direction is opposite the first direction.

23. The assembly of claim 19 further including velocity limiting means for limiting the velocity of second member with respect to the first member.

24. A telescoping assembly, the assembly comprising:

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

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

a nut mounted to the threaded shaft for movement there along, the nut forming a first frusto-conically shaped engaging surface proximate one end;

a locking member forming a second frusto-conically shaped engaging surface proximate the first engaging surface, the locking member moveable between a locking position with the second surface contacting the first surface and restricting rotation of the nut and an unlocking position with the second surface separated from the first surface;

a second member supported by the first member for movement along the extension axis, the second member also supported by the nut for movement therewith; and

a biaser biasing the locking member toward the nut and biasing the second engaging surface toward the first engaging surface.

25. The assembly of claim 24 wherein the nut includes first and second nut members, the first nut member forming a threaded opening for receiving the threaded shaft and the second nut member forming an opening that is aligned with the threaded opening and that passes the shaft, the first nut member secured to the second nut member, the first nut member formed of a low friction material and the second nut member formed of a high friction material.

26. The assembly of claim 25 wherein the second nut member is formed of thermal plastic urethane.

27. The assembly of claim 24 wherein the locking member is formed of powdered metal.

28. A support assembly, the assembly comprising:

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

a second 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 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 members into the extended position wherein the applied force is substantially constant irrespective of the position of the second member with respect to the first member; and

a locking mechanism including at least a first locking member supported by at least one of the first and second members, the first locking member moveable between a locked position wherein the locking member substantially minimizes movement of the second member with respect to the first member and an unlocked position wherein the first locking member allows movement of the second member with respect to the first member.

29. The assembly of claim 28 wherein the locking mechanism includes a first coupler supported by the first member, a second coupler supported by the second member proximate the first coupler and a locking member, the second coupler operable to move with respect to the first coupler and with respect to the first member when the second member moves with respect to the first member, the first locking member supported proximate the second coupler and operable to engage and disengage the second coupler when in the locked and unlocked positions, respectively, when the locking member engages the second coupler, the locking member restricting movement of the second coupler with respect to each of the first coupler and the first member.

30. The assembly of claim 29 further including an operator for controlling the locking member to engage and disengage the second coupler.

31. The assembly of claim 30 wherein the first locking member is a lever having a cam surface and linked for pivotal movement between the unlocked and locked positions.

32. The assembly of claim 31 further including a locking spring that biases the lever into the locked position.

33. The assembly of claim 29 further including a second locking member and at least a first biaser, the second locking member supported by the second member and proximate the second coupler, the first biaser supported by the second locking member and biasing the second coupler away from the second locking member wherein, when a load on the table top is within a first range, the first biaser separates the second coupler from the second locking member and, when the load on the table top is within a second range, the second coupler contacts the second locking member and inhibits movement of the second coupler.

34. The assembly of claim 33 further including a third locking member and a second biaser, the third locking member supported by the second member and proximate the second coupler, the second biaser supported by the third locking member and biasing the second coupler away from the third locking member wherein, when the load on the top is within the first range, the second biaser separates the second coupler from the third locking member and, when the load is within a third range, the second coupler contacts the third locking member and movement of the second coupler is restricted.

35. The assembly of claim 34 wherein the first coupler is a threaded shaft and the second coupler is a nut mounted to the shaft and wherein the threaded shaft is mounted to the first column and is substantially parallel to the vertical extension axis.

36. The assembly of claim 35 wherein the second and third locking members are mounted to the second member on opposite sides of the nut and wherein the first and second biasers are one of coil springs and disc springs.

37. The assembly of claim 33 wherein the first coupler is a threaded shaft and the second coupler is a nut mounted to the shaft and wherein the threaded shaft is mounted to the first member and is substantially parallel to the vertical extension axis.

38. The assembly of claim 28 wherein the locking mechanism further includes a threaded shaft linked to and stationary with respect to the first member and aligned substantially along the extension axis and a nut mounted to the threaded shaft for movement there along, the second member coupled to the nut for movement therewith along the extension axis, the first locking member supported adjacent the nut such that, when the first locking member is in the locked position, the first locking member restricts rotation of the nut with respect to the shaft.

39. The assembly of claim 38 wherein the locking assembly further includes a housing and a biaser, the housing forming a first stop surface and a first bearing surface, the housing supported by the second column for movement therewith, a first space located adjacent the first stop member, the biaser mounted between the first bearing surface and the nut, the biaser tending to bias the nut away from the first stop surface wherein, with the first locking member restricting rotation of the nut, when a force within a first range is applied to the second member along a first trajectory tending to move the first stop surface toward the nut, the first bearing surface and the nut compress the biaser so that the nut contacts the first stop surface and the first stop surface tends to separately restrict movement of the nut.

40. The assembly of claim 39 wherein, when a force within a second range which is less than the first range is applied to the second member along the first trajectory, the biaser maintains a space between the nut and the first stop surface.

41. The assembly of claim 39 further including an annular bearing ring between the biaser and the nut and that surrounds the threaded shaft.

42. The assembly of claim 41 wherein the biaser is one of a coil spring and a disc spring forming a spring passageway and wherein the threaded shaft passes through the spring passageway.

43. The assembly of claim 41 wherein the housing includes a first stop member and a first bearing member that form the first stop surface and the first bearing surface, respectively, and, wherein, the first bearing member and first stop member form aligned openings through which the threaded shaft passes.

44. The assembly of claim 43 wherein the spring is positioned between the first bearing surface and the first stop surface, the apparatus further including a first plunger between the spring and the annular bearing ring that passes through the opening formed by the first stop member.

45. The assembly of claim 39 wherein the housing forms a second stop surface and a second bearing surface, the first space located between the first and second stop surfaces, the assembly further including a second biaser mounted between the second bearing surface and the nut on a side of the nut opposite the first biaser, the second biaser tending to bias the nut away from the second stop surface, wherein, with the locking means restricting rotation of the nut, when a force within a second range is applied to the second column along a second trajectory opposite the first trajectory and tending to move the second stop surface toward the nut, the second stop surface and the nut compress the second biaser so that the nut contacts the second stop surface and the second stop surface tends to separately restrict movement of the nut.

46. The assembly of claim 45 wherein when a force within a third range which is less than the first range is applied to the second column along the first trajectory, the first biaser maintains a space between the nut and the first stop surface and when a force within a fourth range which is less than the first range is applied to the second column along the second trajectory, the second biaser maintains a space between the nut and the second stop surface

47. The assembly of claim 45 further including first and second annular bearing rings between the first biaser and the nut and the second biaser and the nut, respectively, where each of the bearing rings surrounds the threaded shaft.

48. The assembly of claim 47 wherein each of the bearing rings is one of a needle bearing ring and a ball bearing ring.

49. The assembly of claim 47 wherein the housing includes a first stop member, a first bearing member, a second stop member and a second bearing member that form the first stop surface, the first bearing surface, the second stop surface and the second bearing surface, respectively, and, wherein, the first bearing member, first stop member, second bearing member and second stop member form aligned openings through which the threaded shaft passes.

50. The assembly of claim 49 wherein the first spring is positioned between the first bearing surface and the first stop member and the second spring is positioned between the second bearing surface and the second stop member, the apparatus further including a first plunger between the first spring and the first bearing ring that passes through the opening formed by the first stop member and a second plunger between the second spring and the second bearing ring that passes through the opening formed by the second stop member.

51. The assembly of claim 28 further including a table top member wherein one of the first and second members supports the table top member in a substantially horizontal orientation.

52. The assembly of claim 51 wherein the table top is supported by the second member and wherein the second member and table top together have a weight greater than 25 pounds.

53. The assembly of claim 28 further including velocity limiting means for limiting the velocity of second member with respect to the first member.

54. The assembly of claim 28 wherein the spring is a compression coil spring.

55. The assembly of claim 28 wherein the equalizer includes a strand and a cam pulley, the cam pulley mounted to the second column for rotation about a pulley axis substantially perpendicular to the 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.

56. The assembly of claim 55 wherein the spring forms a spring passageway and wherein the first end of the strand passes at least part way through the passageway before linking to the second end of the spring.

57. The assembly of claim 55 wherein the cam pulley is a spiral cam pulley.

58. The assembly of claim 51 wherein the spring is a coil spring and is aligned generally parallel to the vertical extension axis.

59. The assembly of claim 28 wherein the second member forms a passageway, the equalizer assembly includes a cam pulley and a strand having first and second ends linked to the second end of the spring and to the first member, respectively, and a central section wrapped around the pulley and, wherein, the cam pulley and spring are mounted within the passageway.

60. The assembly of claim 59 wherein the cam pulley is mounted by an annular bearing race to the second member for rotation about a cam axis.

61. The assembly of claim 59 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.

62. The assembly of claim 61 wherein the first radii portion is at least 0.5 inches irrespective of the relative positions of the first and second columns.

63. The assembly of claim 62 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.

64. The assembly of claim 28 wherein the spring is a linear spring.

65. The assembly of claim 28 further including rollers between the first and second members that facilitate movement of the second member along the extension axis.

66. The assembly of claim 28 wherein the equalizer assembly is adjustable to adjust the force between the first and second members.

67. The assembly of claim 28 wherein the stroke of the sliding motion of the second member is at least twelve inches.

68. The assembly of claim 29 wherein the first coupler is a threaded shaft and the second coupler is a nut received on the shaft that forms a first engaging surface adjacent one end of the nut, the first locking member forming a second engaging surface proximate the first engaging surface and that contacts the first engaging surface when the first locking member is in the locking position.

69. The assembly of claim 68 wherein the first engaging surface is frusto-conically shaped.

70. The assembly of claim 69 wherein the second engaging surface is frusto-conically shaped.

71. The assembly of claim 69 wherein the locking mechanism further includes a spring that biases the second engaging surface of the first locking member toward the first engaging surface of the nut.

72. The assembly of claim 71 wherein the first locking member includes at least a first lateral lift extension and an operator mechanically linked to the first lateral lift extension, the operator, when activated, moving the lateral lift extension and the first locking member against the biasing force of the spring to the unlocked position.

73. The assembly of claim 69 wherein the first engaging surface is formed of a high friction material.

74. The assembly of claim 73 wherein the nut includes first and second nut members, the first nut member forming a threaded opening for receiving the shaft and the second member forming a non-threaded opening for passing the shaft and also forming the first engaging surface, the first nut member formed of a relatively low friction material and the second nut member formed of a relatively high friction material.

75. 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 housing forming a first stop surface and a first bearing surface, the housing linked to the second member for movement therewith, a first space located adjacent the first stop member;

a nut mounted to the threaded shaft for movement there along and located within the first space adjacent the first stop surface;

a lock for restricting and allowing rotation of the nut with respect to the threaded shaft;

a biaser mounted between the first bearing surface and the nut, the biaser tending to bias the nut away from the first stop surface wherein, with the locking means restricting rotation of the nut, when a force within a first range is applied to the second member along a first trajectory tending to move the first stop surface toward the nut, the first bearing surface and the nut compress the biaser so that the nut contacts the first stop surface and the first stop surface tends to separately restrict movement of the nut.

76. The assembly of claim 75 wherein, when a force within a second range which is less than the first range is applied to the second member along the first trajectory, the biaser maintains a space between the nut and the first stop surface.

77. The assembly of claim 75 wherein the housing forms a second stop surface and a second bearing surface, the first space located between the first and second stop surfaces, the assembly further including a second biaser mounted between the second bearing surface and the nut on a side of the nut opposite the first biaser, the second biaser tending to bias the nut away from the second stop surface, wherein, with the locking means restricting rotation of the nut, when a force within a second range is applied to the second member along a second trajectory opposite the first trajectory and tending to move the second stop surface toward the nut, the second stop surface and the nut compress the second biaser so that the nut contacts the second stop surface and the second stop surface tends to separately restrict movement of the nut.

78. The assembly of claim 77 wherein a force within a third range which is less than the first range is applied to the second member along the first trajectory, the first biaser maintains a space between the nut and the first stop surface and when a force within a fourth range which is less than the first range is applied to the second member along the second trajectory, the second biaser maintains a space between the nut and the second stop surface

79. The assembly of claim 77 further including first and second annular bearing rings between the first biaser and the nut and the second biaser and the nut, respectively, where each of the bearing rings surrounds the threaded shaft.

80. The assembly of claim 79 wherein each of the bearing rings is one of a needle bearing ring and a ball bearing ring.

81. The assembly of claim 79 wherein the first and second biasers are first and second springs that form first and second spring passageways, respectively, and, wherein, the threaded shaft passes through the spring passageways.

82. The assembly of claim 75 wherein the locking means includes a cam having a cam surface and linked for pivotal movement from an unlocked position where the cam surface is separate from the nut and a locked position wherein the cam surface contacts the nut and restricts movement.

83. The assembly of claim 82 further including a locking spring that biases the cam into the locked position.

84. The assembly of claim 75 further including an operator for controlling the locking means to engage and disengage the nut.

85. The assembly of claim 75 further including a table top member wherein one of the first and second elongated members supports the table top member in a substantially horizontal orientation.

86. The assembly of claim 75 further including velocity limiting means for limiting the velocity of second member with respect to the first member.