US20060220431A1

US20060220431A1 - Chair control device

Info

Publication number: US20060220431A1
Application number: US11/083,436
Authority: US
Inventors: Ing Kwa
Original assignee: SITWELL LLC
Current assignee: SITWELL LLC
Priority date: 2005-03-17
Filing date: 2005-03-17
Publication date: 2006-10-05
Also published as: CN101036554A; CA2539854A1

Abstract

A mechanism is provided for an office chair to adjust the tilt of the seat portion relative to the base of the chair. The mechanism includes an adjustable member tiltably mounted on a base, a compression spring bearing on the adjustable member and connected to the base using a retaining bolt running through the center of the compression spring, and a clutch device fixably attached to the base extending to the adjustable member, which clutch device is capable of holding the adjustable member in a fixed position relative to the base.

Description

FIELD OF THE INVENTION

The present invention relates to an adjustment mechanism for a chair allowing relative displacement of two chair parts. In an exemplary embodiment, the invention provides a seat tilt and locking device.

BACKGROUND

It is typical in office chairs for the seat to tilt rearwardly as an occupant leans back in the seat. To accommodate this motion, known chair control devices allow a seat portion of a chair to tilt in relation to its wheeled support. These chair control devices are provided with an adjustable spring to counteract the rearward force exerted on the chair by the user, which force will ordinarily cause the chair to return to an upright position when unoccupied. This adjustable spring may be pretensioned by a user to a greater or lesser degree to cause the spring to exert a greater or lesser reaction force to the rearward force supplied by the user.
Sophisticated chair control devices are known which, in addition to having an adjustable spring, incorporate a clutch assembly which allows a user to lock the chair in any reclined or upright position throughout its range of motion. Simpler devices are also known which have a tilt lock mechanism which merely prevents the chair from righting itself when in a reclined position and/or locks the chair in an upright position.
The more sophisticated chair control devices which incorporate the clutch assembly feature are far more expensive and complicated to manufacture than the simpler tilt lock mechanisms. This is due to certain design considerations, because of which it has been necessary in the past to use an expensive tilt assembly and torsion spring in devices featuring both an adjustable pretensioned spring for counteracting the tilt force exerted by a user and a clutch assembly for locking in a tilt position.

SUMMARY OF THE INVENTION

In an exemplary embodiment, an adjustment mechanism for a chair comprises a base, an adjustable member tiltably mounted on the base and moveable between a first position and a second position, a compression spring bearing on the adjustable member which urges the adjustable member toward the first position when compressed and a clutch attached to the base and the adjustable member capable of engaging to hold the adjustable member in a fixed position relative to the base between or including the first position and the second position.
In another embodiment, an adjustment mechanism for a chair comprises a base, an adjustable member tiltably mounted on the base and moveable between a first position and a second position, an elastic element bearing on the adjustable member which urges the adjustable member toward the first position when deformed, and a clutch comprising a clutch lever mounted on the base and a clutch assembly attached to the adjustable member. The clutch assembly connects the clutch lever and the adjustable member, and the clutch is capable of engaging to hold the adjustable member in a fixed position relative to the base between or including the first position and the second position.
In yet another embodiment, an adjustment mechanism for a chair comprises a base comprising a first central plate and a first pair of sidewalls extending substantially perpendicularly downward from the first central plate, the first pair of sidewalls being substantially parallel to one another, an adjustable member tiltably mounted on the base below the first central plate moveable between a first position and a second position, an elastic element provided below the adjustable member and the first central plate of the base which bears on the adjustable member and urges the adjustable member toward the first position when deformed, and a clutch attached to the base and the adjustable member capable of engaging to hold the adjustable member in a fixed position relative to the base between or including the first position and the second position.
In yet another embodiment, an adjustment mechanism for a chair comprises a base comprising a first central plate and a first pair of sidewalls extending substantially perpendicularly downward from the first central plate, the first pair of sidewalls being substantially parallel to one another, an adjustable member moveable between a first position and a second position which is tiltably mounted on the base, and which comprises a second central plate, a column mount and a second pair of sidewalls extending substantially perpendicularly downward from the second central plate to the column mount, the second pair of sidewalls being substantially parallel to one another, an elastic element bearing on the adjustable member which urges the adjustable member toward the first position when deformed, and a clutch attached to the base and the adjustable member capable of engaging to hold the adjustable member in a fixed position relative to the base between or including the first position and the second position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a conventional tilt mechanism for use with a chair control device;
FIG. 2 shows another conventional tilt mechanism for use with a chair control device;
FIG. 3 shows an exemplary embodiment of a tilt mechanism for use the present chair control device;
FIG. 4 shows perspective view of an exemplary embodiment of a chair control device wherein the tilt mechanism is concealed beneath a shroud;
FIG. 5 shows another perspective view of the chair control device of FIG. 4 wherein the shroud has been removed;
FIG. 6 shows an overhead view of the chair control device of FIG. 5;
FIG. 7 depicts outlines of an embodiment of the present tilt mechanism in both the reclined and upright positions;
FIG. 8 shows a side view of an exemplary embodiment of a tilt mechanism;
FIG. 9 shows an overhead view of the tilt mechanism of FIG. 8;
FIG. 10A depicts detail 1 of FIG. 8;
FIG. 10B shows an end view of the tilt mechanism of FIG. 8;
FIG. 11 shows an overhead view of an exemplary embodiment of a base of a chair control device;
FIG. 12 shows a side view of the base of FIG. 11;
FIG. 13 shows an end view of the base of FIG. 11;
FIG. 14A depicts detail 1 of FIG. 11;
FIG. 14B depicts section B-B of FIG. 11;
FIG. 14C depicts section A-A of FIG. 11;
FIG. 15A shows a top view of one embodiment of a tilt clutch bracket;
FIG. 15B shows a side view of the tilt clutch bracket of FIG. 15A; and
FIG. 15C depicts detail 2 of FIG. 12.
Before any embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangements of components set forth in the following description, or illustrated in the drawings. The invention is capable of alternative embodiments and of being practiced or being carried out in various ways. Specifically, numerical dimensions, where they appear on the following drawings, represent those of exemplary embodiments only and may be modified by one skilled in the art as conditions warrant. Also, it is to be understood that the terminology used herein is for the purpose of illustrative description and should not be regarded as limiting.

DETAILED DESCRIPTION

FIG. 1 shows a conventional tilt mechanism for use with a chair control device. This device, known in the art as a “tilt lock” device, comprises a tilt mechanism 10 pivotably connected to a base 11. The underside of the mechanism has a column mount 15 on its underside which may be mounted on the column of the wheeled support of a standard office chair. As the tilt mechanism 10 rotates relative to the base 11, this causes the wheeled support of the chair to tilt relative to a seat of the chair mounted on the top surface of the base 11.
Counteracting the tendency of the tilt mechanism 10 to rotate relative to the base 11 is the compression spring 13 compressed between the underside of the tilt mechanism 10 and a knob 12 secured to the base 11 by the retaining bolt 14. The knob 12 is adjustably mounted on the retaining bolt 14 so that it may be rotated to add or remove a preloading force to the compression spring 13. This preloading force causes the tilt mechanism 10 to rotate more or less stiffly relative to the base 11 when subjected to an outside force. Through this mechanism, a user of the chair can adjust the recline resistance of her chair to her personal comfort.
FIG. 2 shows another conventional tilt mechanism for use with a chair control device. Similarly to the device of FIG. 1, a tilt mechanism 20 is provided which rotates relative to the base 21, and the tilt mechanism 20 is provided with a column mount 25 on its underside. In contrast to the device of FIG. 1, in place of a compression spring bearing on the outside of the tilt mechanism 20 a torsion spring 23 is provided within the tilt mechanism 20, and a knob 22 bears directly on the tilt mechanism 20. The knob 22 is drawn downwards by a retaining hook 24 which passes through an opening in the tilt mechanism 20 to engage with a torsion spring 23 within. The opposition end of the torsion spring 23 bears on the base 21, and is provided with a stop 28 for this purpose.
In the conventional mechanism shown in FIG. 2, the compression spring has been replaced by the torsion spring 23 in part to accommodate the addition of the clutch assembly 26. This assembly connects the base 21 and the tilt mechanism 20 and allows the rotation of one to be halted relative to the other at any position throughout its range. While the clutch assembly provides a useful functionality to the chair control device of FIG. 2, it cannot be added to the chair control device shown in FIG. 1 as is without significantly redesigning the tilt mechanism 11 requiring at the very least that it be made larger overall, significantly so in the area of the added clutch assembly. This larger tilt mechanism 20 cannot easily accommodate a compression spring without impeding its function. Furthermore, if one were to try to add a compression spring to the mechanism shown in FIG. 2 by placing it between the knob 22 and the tilt mechanism 20, the knob 22 would extend an unacceptably far distance below the base 21 and interfere with other functions of the chair itself. Thus in the known mechanism of FIG. 2, in place of a compression spring a torsion spring 23 is used. Although the redesigned tilt mechanism 20 provides tilt functionality to the chair control device and accommodates the newly added clutch assembly 26, its complexity makes it difficult to manufacture and thus relatively expensive. Likewise the torsion spring 23 is also more expensive than more common compression springs. As such the chair control device of FIG. 2, while providing increased functionality over the chair control device of FIG. 1, does so only at an increased cost in materials.
FIG. 3 shows an exemplary embodiment of a tilt mechanism for use the present chair control device. The device has a tilt mechanism 30 which as in the previous figures rotates relative to the base 31. However unlike the prior art figures, this embodiment of a tilt mechanism features a clutch assembly 36 together with a compression spring 33, as well as a relatively simple design for the tilt mechanism 30 comprising a central plate 38, a column mount 35 and a pair of sidewalls 37 extending from the central plate to the column mount. In one embodiment, the pair of sidewalls 37 are substantially parallel to one another and substantially perpendicular to the central plate 38. In another embodiment, the pair of sidewalls reinforce and add rigidity to the central plate. In yet another embodiment, an incline 37 may be provided on the central plate 38, on which incline 37 the compression spring 33 bears.
Because the tilt mechanism 30 is provided with these sidewalls 37 extending from the central plate 38 away from the base 31 towards the bottom of the device in contrast to the tilt mechanisms of the prior art, the surface of the central plate 38 on which a spring bears can be closer to the base 31 than would otherwise be the case. As such, a compression spring can be used rather than torsion spring of the prior art. To further accommodate this substitution, the clutch assembly 36 and a clutch lever (not shown) can be provided as a unit fixably mounted on the base 31 below which point it pivotably engages the tilt mechanism 30. A knob 32 is also provided secured to the base 31 by the retaining bolt 34. The knob 32 is adjustably mounted on the retaining bolt 34 so that it may be rotated to add or remove a preloading force to the compression spring 33.
FIG. 4 shows perspective view of an exemplary embodiment of a chair control device wherein the tilt mechanism is concealed beneath a shroud. The device comprises a base 51 and a tilt mechanism (not shown) which may be pivotably connected thereto at the primary pivot point 42. A shroud 44 attached to the base 51 at least partially covers the tilt mechanism to reduce the risk to a user of a user's finger being caught between the tilt mechanism and the base 51. A knob 52 is provided which may be adjusted to add or remove a preloading force to the compression spring 59 mounted beneath the knob 52 on the tilt assembly. In an alternative embodiment, the spring 59 may be any elastic element. The base 51 is provided with tabs 67 through which the device may be attached by bolts or another fastener to the underside of the seat portion of a chair (not shown).
The tilt mechanism supports the column mount 55 which can be mounted on the column of a standard wheeled support for an office chair (not shown). This column may include a gas cylinder having two-chambers separated by a normally closed valve. A user actuator 62 may be provided tiltably mounted in a housing above the valve opening member, and which may be operated to depress the valve opening member in order to open the cylinder valve to permit height adjustment of the seat.
Further adjustment devices may be provided as part of the present chair control device including a primary clutch lever 63 attached to the base 51 by a clutch housing 43. The primary clutch lever 63 is provided to operate a clutch assembly at least partially concealed within the shroud 44, which assembly comprises at least one clutch plate and a clutch pin 41. The primary clutch lever 63 may be operated to engage or disengage the clutch assembly to prevent or permit tilt mechanism to move relative to the base 51. A secondary adjustment assembly 60 may be provided to support element for a chair backrest, the motion of which secondary adjustment assembly 60 may halted by the engagement of a secondary clutch lever 61. A recline locking lever 65 may be provided mounted on the base 51 having a recline locking stop 66 thereon which may be slid into a blocking position to prevent the tilt assembly from being adjusted to the fully upright position relative to the base 51.
FIG. 5 shows another perspective view of the chair control device of FIG. 4 wherein the shroud has been removed so that the tilt mechanism 50 is visible. As previously mentioned, the tilt mechanism 50 may be pivotably connected to the base 51 at a primary pivot point 42. Also visible in FIG. 5 is a spring loaded clutch bracket 64 which the primary clutch lever 63 mounted on the base 51 may be operated to disengage, as well as a clutch assembly 56. FIG. 6 shows an overhead view of the chair control device of FIG. 5 having a clutch spring 68 for spring loading the clutch bracket 64. The tilt mechanism 50 is shown here having reinforcing ridges 69 thereon to provide additional stiffness. FIG. 7 depicts an embodiment of the present chair control device wherein an outline of the base 71 is shown in relation to outlines of the tilt mechanism in both the reclined position 70 a as well as an upright p006Fsition 70 b.
FIG. 8 shows a side view of an exemplary embodiment of a tilt mechanism 80 provided with a primary pivot point 82 for engaging with a base of a chair control device, column mount flanges 85 for engaging with a column mount, a user actuator 84 to permit height adjustment of the seat and an actuator slot 83 therefore, an incline 86 to provided a bearing surface for a compression spring or other elastic element, and a retaining bolt passage 87 through which a retaining bolt may pass to secure a control knob to the base of a chair control device.
FIG. 9 shows an overhead view of the tilt mechanism 80 of FIG. 8 wherein clutch mounts 88 are visible. In one embodiment, the clutch mounts 88 comprise raised tabs which pivotably engage the at least one clutch plate of the clutch assembly of the chair control device. The column mount flanges 85 are also shown having at least one rivet hole 89 to which a plate column mount may be attached to receive the column of a wheeled or other support of a chair. Reinforcing flanges 92 extending downward from the second central plate 90 to reinforce the second central plate 90 are also shown in FIGS. 8, 9 and 10B.
FIG. 10A depicts detail 1 of FIG. 8 showing the user actuator 84 to permit height adjustment of the seat and the actuator slot 83 therefore. FIG. 10B shows an end view of the tilt mechanism of FIG. 8 wherein the a tilt mechanism 80 comprises a second central plate 90, a second pair of sidewalls 91, and column mount flanges 85 which may be attached to a column mount, in which case a passage is provided through the tilt mechanism 80 defined by the second central plate 90, the column support and the first pair of sidewalls 91. In an exemplary embodiment, the second pair of sidewalls 91 extend substantially perpendicular from the central plate 90, and are substantially parallel to one another.
FIG. 11 shows an overhead view of an exemplary embodiment of a base 111 for use with a chair control device comprising tabs 117 through which the base 111 may be attached by bolts or other fasteners to the underside of the seat portion of a chair (not shown), a raised portion 115 and retaining bolt socket 116 for securing an end of a retaining bolt, a protrusion 114, and a neck 113 which narrows to provide an attachment point for a secondary adjustment assembly 60. In one embodiment, base 111 comprises a base end plate 112 though which a recline locking stop 66 of a recline locking lever 65 passes.
FIG. 12 shows a side view of the base 111 of FIG. 11 having a passage 121 for a clutch bracket 64, a passage 122 for a clutch pin 41, an actuator slot 118, a passage 123 for a secondary clutch pin, secondary pivot point 124 for a secondary adjustment assembly 60, and a primary pivot point 125 for a tilt mechanism 50. FIG. 13 shows an end view of the base 111 of FIG. 11 wherein the base comprises a central plate 131 and a pair of sidewalls 132. In an exemplary embodiment, the pair of sidewalls 132 extend substantially perpendicularly downward from the central plate 131 and are substantially parallel to one another.
FIG. 14A depicts the protrusion 114 highlighted in detail 1 of FIG. 11, FIG. 14B depicts the raised portion 115 highlighted in section B-B of FIG. 11, and FIG. 14C depicts the raised portion 115 and retaining bolt socket 116 highlighted in section A-A of FIG. 11. FIG. 15A shows a top view of one embodiment of a tilt clutch bracket 154 having a clutch pin passage 151, FIG. 15B shows a side view of the tilt clutch bracket 154, and FIG. 15C depicts detail 2 of FIG. 12.

Claims

1. An adjustment mechanism for a chair, the mechanism comprising:

a base;

an adjustable member tiltably mounted on the base and moveable between a first position and a second position;

a compression spring bearing on the adjustable member which urges the adjustable member toward the first position when compressed; and

a clutch attached to the base and the adjustable member capable of engaging to hold the adjustable member in a fixed position relative to the base between or including the first position and the second position.

2. The adjustment mechanism of claim 1, further comprising a manual adjustment device bearing on the compression spring and a retaining member passing thorough the compression spring,

wherein the retaining member is held in tension between the manual adjustment device and the base.

3. The adjustment mechanism of claim 1, wherein the base comprises a central plate and a pair of sidewalls extending substantially perpendicularly downward from the central plate, the pair of sidewalls being substantially parallel to one another.

4. The adjustment mechanism chair of claim 3, further comprising a shroud attached to the base below the adjustable member,

wherein the shroud at least partially covers the adjustable member to reduce the risk to a user of a user's finger being caught between the adjustable member and the base.

5. The adjustment mechanism chair of claim 1, further comprising a slider having an abutment thereon mounted on the base which may be slid into a blocking position to prevent the adjustable member from reaching the first position.

6. The adjustment mechanism of claim 3, further comprising a seat connected above and to the base and a support connected below and to the adjustable member,

wherein moving the adjustable member to the first position causes the seat to assume an upright position relative to the support, and

wherein moving the adjustable member to the second position causes the seat to assume a reclined position relative to the support.

7. An adjustment mechanism for a chair, the mechanism comprising:

a base;

an elastic element bearing on the adjustable member which urges the adjustable member toward the first position when deformed; and

a clutch comprising a clutch lever mounted on the base and a clutch assembly attached to the adjustable member,

wherein the clutch assembly connects the clutch lever and the adjustable member, and

wherein the clutch is capable of engaging to hold the adjustable member in a fixed position relative to the base between or including the first position and the second position.

8. The adjustment mechanism of claim 7, wherein the elastic element is a compression spring.

9. The adjustment mechanism of claim 8, further comprising a manual adjustment device bearing on the compression spring and a retaining member passing thorough the compression spring,

10. The adjustment mechanism of claim 7, wherein the clutch lever is tiltably mounted on the base and may be operated to disengage a spring loaded bracket.

11. The adjustment mechanism chair of claim 7, further comprising a slider having an abutment thereon mounted on the base which may be slid into a blocking position to prevent the adjustable member from reaching the first position.

12. The adjustment mechanism of claim 7, wherein the base comprises a central plate and a pair of sidewalls extending substantially perpendicularly downward from the central plate, the pair of sidewalls being substantially parallel to one another.

13. The adjustment mechanism chair of claim 12, further comprising a shroud attached to the base below the adjustable member,

14. The adjustment mechanism of claim 12, further comprising a seat connected above and to the base and a support connected below and to the adjustable member,

15. The adjustment mechanism of claim 7, wherein the clutch assembly comprises at least one clutch plate and a clutch pin, and

wherein when the clutch lever is operated to disengage a spring loaded bracket, the at least one clutch plate is released to move relative to the clutch pin which in turn releases the clutch assembly to move relative to the base.

16. The adjustment mechanism of claim 15, wherein the clutch assembly is attached to the adjustable member at a pivot point lying between the clutch pin and the central plate of the base.

17. The adjustment mechanism of claim 16, wherein the pivot point is provided below the central plate of the base and above the pivot pin of the clutch assembly.

18. An adjustment mechanism for a chair, the mechanism comprising:

a base comprising a first central plate and a first pair of sidewalls extending substantially perpendicularly downward from the first central plate, the first pair of sidewalls being substantially parallel to one another;

an adjustable member tiltably mounted on the base below the first central plate moveable between a first position and a second position;

an elastic element provided below the adjustable member and the first central plate of the base which bears on the adjustable member and urges the adjustable member toward the first position when deformed; and

19. The adjustment mechanism of claim 18, wherein the elastic element is a compression spring.

20. The adjustment mechanism of claim 19, further comprising a manual adjustment device bearing on the compression spring and a retaining member passing thorough the compression spring,

21. The adjustment mechanism chair of claim 18, further comprising a shroud attached to the base below the adjustable member,

22. The adjustment mechanism chair of claim 18, further comprising a slider having an abutment thereon mounted on the base which may be slid into a blocking position to prevent the adjustable member from reaching the first position.

23. The adjustment mechanism of claim 18, further comprising a seat connected above and to the base and a support connected below and to the adjustable member,

24. An adjustment mechanism for a chair, the mechanism comprising:

an adjustable member moveable between a first position and a second position which is tiltably mounted on the base, and which comprises a second central plate, a column mount and a second pair of sidewalls extending substantially perpendicularly downward from the second central plate to the column mount, the second pair of sidewalls being substantially parallel to one another;

25. The adjustment mechanism of claim 24, wherein a passage is provided through the adjustable member defined by the column support, the first pair of sidewalls and the second central plate.

26. The adjustment mechanism of claim 24, wherein the adjustable member further comprises reinforcing flanges extending downward from the second central plate to reinforce the second central plate.

27. The adjustment mechanism of claim 24, wherein the elastic element is a compression spring.

28. The adjustment mechanism of claim 27, further comprising a manual adjustment device bearing on the compression spring and a retaining member passing thorough the compression spring,

29. The adjustment mechanism chair of claim 24, further comprising a shroud attached to the base below the adjustable member,

30. The adjustment mechanism chair of claim 24, further comprising a slider having an abutment thereon mounted on the base which may be slid into a blocking position to prevent the adjustable member from reaching the first position.

31. The adjustment mechanism of claim 24, further comprising a seat connected above and to the base and a support connected below and to the adjustable member,