WO1994026148A1

WO1994026148A1 - Front tilt mechanism for chair

Info

Publication number: WO1994026148A1
Application number: PCT/CA1993/000211
Authority: WO
Inventors: William S. Stumpf
Original assignee: Doerner Products Ltd.
Priority date: 1992-02-25
Filing date: 1993-05-18
Publication date: 1994-11-24
Also published as: CA2061813A1

Abstract

A front tilt mechanism for a chair is disclosed which can be coupled directly to the underside of the chair seat or alternatively may be incorporated into an existing rear tilt mechanism housing. The forward tilt mechanism includes a mounting bracket mountable to the underside of a chair seat and seat support spindle bracket pivotally connected to the mounting bracket. The spindle bracket is located in such a way that the chair seat is tilted forward by the user shifting his centre of gravity, and wherein, when in use, the chair seat is movable with respect to the spindle bracket between a first position in which the chair seat is untilted with respect to the horizontal and a second position in which the chair seat is tilted forward at an angle with respect to the horizontal.

Description

FRONT TILT MECHANISM FOR CHAIR

FIELD OF THE INVENTION

The present invention relates to a tilt mechanism for a chair.

BACKGROUND OF THE INVENTION

There is a need for a chair having a tilt mechanism which allows a user sitting in the chair to tilt the chair seat forward in addition to tilting the chair seat in a rearward direction. This is necessitated by posture requirements or simply a need for a more comfortable seating arrangement when performing various tasks involving reaching by the user. For example, individuals sitting at work stations may wish to tilt their chairs forward while making entries on a computer keyboard and tilt rearward while reading documents. While it is desirable to have a seat rearward tilt mechanism which utilizes spring bias, it has been found that a spring biased forward tilt mechanism is not desirable since the user must actively push downwards against the front of the chair seat in order to maintain the seat angle in a forward tilt position, which can become uncomfortable. In one type of known tilt mechanism the aforesaid disadvantage is circumvented by utilizing the spring of the rearward tilt mechanism to drive the seat forward. However, this type of arrangement has its own disadvantages in that the rearward tilt mechanism must first be manually disengaged in order to utilize the spring for the forward tilt operation which presents an inconvenience. In addition, during forward tilting the user is literally thrown forward in the chair seat with considerable force. Accordingly, it would be desirable to provide a tilt mechanism which avoids the above mentioned disadvantages. SUMMARY OF THE INVENTION

The subject invention provides a front tilt mechanism for a chair seat in which the forward tilt function is separated from the rearward tilt function. Further, the forward tilt mechanism disclosed herein permits a user to tilt the chair seat forward by merely shifting his or her centre of gravity, and hence there is no spring bias which must be overcome in order to maintain the chair seat in a forward tilt position.

In one aspect, the tilt mechanism includes a seat support spindle receiving means pivotally attachable to the underside of a chair seat for receiving a seat support spindle, and wherein, when in use, the chair seat is movable with respect to the spindle receiving means between an untilted position with respect to the horizontal and a tilted position in which the chair seat is tilted forward at an angle by the user shifting his centre of gravity forward from a first position. The seat is returned to the untilted position by ,the user either shifting his centre of gravity back to the first position or by vacating the seat.

In another aspect of the invention there is provided a chair having a forward tilt mechanism which includes a chair support base and a chair seat support spindle attached to the support base which extends upwardly therefrom. The chair is provided with a chair seat operably coupled to said seat support spindle, said operable coupling including a chair spindle receiving means pivotally attachable to the underside of the chair seat for receiving the seat support spindle, the chair seat being movable with respect to the spindle receiving means between a first position in which the chair seat is untilted with respect to the horizontal and a second position in which the chair seat is tilted forward at an angle with respect to the horizontal. The spindle receiving means is pivotally attached to the seat underside at a position such that the chair seat is tilted forward by the user shifting his centre of gravity.

In still another aspect of the invention there is provided an improved tilt mechanism for a chair, the chair being of the type having a rearward tilt mechanism which includes a housing for enclosing the rearward tilt mechanism, wherein the housing includes a first housing portion to which a chair seat is attachable, and a second housing portion coupled to the first housing portion in such a way that when, in use, as the chair seat is tilted rearwardly, the first housing portion pivots with respect to the second housing portion. The improvement comprises a chair spindle receiving means operably coupled to the second housing portion for receiving a seat support spindle. The chair seat is movable with respect to the receiving means between a first position in which the chair seat is substantially untilted with respect to the horizontal and a second position in which the chair seat is tilted forward at an angle with respect to the horizontal. The spindle receiving means is operably coupled to the second housing portion at a position such that the chair seat is tilted forward by the user shifting his centre of gravity.

In a further aspect of the invention there is provided a tilt mechanism for a chair offering both forward and rearward tilt functions. The tilt mechanism includes a housing enclosing a rearward tilt mechanism, the housing including a first bracket having a top surface and a bottom surface. A chair seat attachable to the top surface of the first bracket and the housing is provided with a second bracket pivotally mounted to the first bracket in facing relationship with the bottom surface of the first bracket. The rearward tilt mechanism is located adjacent one end of the housing between two facing end portions of the brackets. The second bracket is provided with a cut-out portion located adjacent the other end of the second bracket. The tilt mechanism includes a seat support spindle receiving bracket located in the cut-out portion and pivotally mounted to the second bracket adjacent an end of the spindle receiving bracket closest to said other end of the second bracket. The tilt mechanism housing includes a stop means positioned in the housing so that it is intercepted by the spindle receiving bracket after the housing pivotally moves with respect to the spindle support bracket a predetermined distance. The spindle receiving bracket is pivotally mounted to the second housing portion at a position such that, when in use, the chair seat is tilted forward by the user shifting his centre of gravity until the stop means is intercepted by the spindle receiving bracket wherein the seat is in the forward tilted position.

BRIEF DESCRIPTION OF THE DRAWINGS

The following is a description, by way of example only, of various embodiments of the invention, reference being had to the accompanying drawings, in which:

Figure 1 is a schematic perspective view of a chair fitted with a tilt mechanism constructed in accordance with the subject invention;

Figure 2 is a side elevational view of one embodiment of a tilt mechanism;

Figure 3 is a view of a portion of the tilt mechanism looking along arrow 5 of Figure 2;

Figure 4 is a perspective view, broken away, of the tilt mechanism of Figure 2 illustrating one embodiment of the invention;

Figure 5 is a perspective view of the encircled portion 5 of Figure 1 illustrating another embodiment of the invention;

Figure 6 is a side elevational view, partially broken away, of the chair and tilt mechanism of Figure 5 in operation with the chair in the untilted position;

Figure 7 is similar to Figure 6 but with the chair seat tilted fully forwards;

Figure 8 illustrates the chair seat in the fully forward tilted position similar to Figure 7 but with the tilt mechanism adjusted to give a smaller forward angle of tilt;

Figure 9 is a plan view of an alternative forward tilt mechanism; and

Figure 10 is a side elevation of the embodiment of Figure 9.

DETAILED DESCRIPTION OF THE INVENTION

Referring first to Figure 1 there is shown a chair generally at 20 having a base with supporting legs 22 each with support castors 24. Supporting legs 22 are arranged in a star configuration being connected together at a bracket 26. Extending vertically upwards from bracket 26 is a cylindrical support column or spindle 28. Chair 20 includes a seat base 30, a back rest 32 coupled by a support member to base 30 and a seat cushion 34 mounted on base 30. As will be discussed below, the forward tilt mechanism embodying the subject invention may be mounted directly to the underside of a chair seat, or alternatively, it may be incorporated into the housing of a chair rearward tilt mechanism. The incorporation of the subject forward tilt mechanism into a housing of a rearward tilt mechanism will be discussed first.

Referring again to Figure 1, chair 20 is provided with a known rearward tilt mechanism shown generally at 36 which includes a tilt mechanism housing 40 operably coupled between base 30 and spindle 28. Only those structural and functional details of housing 40 and rearward tilt mechanism 36 required for an understanding of the forward tilt mechanism embodying the subject invention will now be discussed .

Referring to Figures 2 and 3, known tilt mechanism 36 includes a housing 40 comprised of a first support bracket 42 having a generally planar portion 44 with a top surface 46 (which may serve as a seat base 30), a bottom surface 48 and side walls 50. Housing 40 includes a second support bracket 54 having a planar portion 56, a portion 58 angled with respect to portion 56 and side walls 60. Brackets 42 and 54 are pivotally coupled together by a pivot rod 62 extending transversely through side walls 50 and 60 of brackets 42 and 54 respectively. Pivot rod 62 extends through a bias spring 64 which in turn extends between side walls 60 of bracket 54.

Tilt mechanism 36 is of the type including a bias spring tension adjustment means 66 including a manual adjustment knob 68 operably coupled to spring 64 and is located at the front end 70 of housing 40 to provide tension adjustment of the spring. Tilt mechanism 36 includes a locking mechanism 72 operably coupled to brackets 42 and 54 in order to lock same in a fixed relationship. Bias spring 64 is coupled between brackets 42 and 54 in such a way that the end portion of bracket 42 located at the front 70 of housing 40 can be pivotally moved away from the front end of bracket 54 located at the front of housing 40 about pivot rod 62 in the direction of arrow A, see Figure 2. This arrangement provides the rearward spring biased tilt action when mechanism 36 is connected to chair 20 with housing 40 mounted to seat base 30 so that front end 70 of housing 40 is under the front of the seat base.

The modification of housing 40 of the known rearward tilt mechanism 36 to provide a forward tilt function, which is the subject of the present invention will now be described. Referring to Figures 2-4, bracket 54 is provided with a cut-out portion 80 in which a generally rectangular bracket 82 is mounted. Bracket 82 includes opposing faces 84 and 86 and opposing side walls 88 and 90. Bracket 82 is provided with holes 92 and 94 located in faces 84 and 86 respectively with the holes being aligned for receiving therein an end portion of seat support spindle 28. Bracket 82 also includes a pair of aligned elongate slots 96 and 98 located in side walls 88 and 90 respectively with each slot having an upper and lower end. Bracket 82 is pivotally mounted to bracket 54 in cut-out portion 80 by a pivot rod 100 extending through aligned apertures in side walls 88 and 90 of bracket 82 and aligned apertures in side walls 60 of bracket 54 at a point adjacent the end of bracket 82 which is spaced furthest from front end 70 of housing 40. Slots 96 and 98 are located adjacent the end of bracket 82 closest to front end 70 of housing 40.

When housing 40 is mounted to the underside of a chair seat the chair spindle 28 is secured in holes 92 and 94 of bracket 82. Bracket 82 is spatially fixed with respect to spindle 28 while housing 40 is subject to pivotal movement.

Housing 40 includes a stop means for stopping the pivotal movement of bracket 82 with respect to the rest of housing 40 thereby defining the ambit of motion of bracket 82. In this embodiment the stop means includes a stop rod 104 extending transversely between side walls 60 of bracket 54 and through slots 96 and 98, see Figures 2 and 4. Therefore, when in use, with spindle 28 securely engaged in holes 94 and 92 of bracket 82, housing 40 can pivot about pivot rod 100 in the direction of arrow B until stop rod 104, which moves along the path of slots 96 and 98, abuts the lower end of the slots so that front end 70 of housing 40 is tilted downward at an angle with respect to bracket 82 and the horizon. In the embodiment of the tilt mechanism shown in Figure 4, stop rod 104 is a cylindrical rod secured at its ends to side walls 60 of bracket 54.

It will be apparent to those skilled in the art that the maximum angle of tilt of housing 40 with respect to bracket 82 which can be achieved is determined by the length of aligned slots 96 and 98 which directly determines the distance through which the housing can pivotally move. Therefore the tilt angle will be determined by the relevant dimensions such as the diameter of the stop rod and length of the slots. A tilt angle in the range 0-10 degrees is suitable for most functions. As illustrated in Figure 4, in the untilted position stop rod 104 is abutting the upper ends of slots 96 and 98 thereby acting as a stop to prevent housing 40 from freely tilting backwards.

It will be appreciated that in another embodiment of the tilt mechanism some other means for preventing rearward tilting may be used, such as a tab 105 extending from portion 56 of bracket 54 over cut-cut portion 80 adjacent the end of bracket 82 closest to front end 70 of housing 40. Tab 105 will abut bracket 84 so as to restrict rearward tilting of the chair seat.

The seat chair is mounted to the housing of the combined tilt mechanism in such a way so that when the seat support spindle 28 is mounted in bracket 82 with a seat comprised of seat base 30 and seat cushion 34 secured to the top surface of bracket 42, housing 40 is in a first untilted, substantially horizontal position as illustrated in Figure 6. Therefore housing 40 is mounted to the underside of seat base 30 so that bracket 82 is positioned with respect to the seat in such a way that the user actuates the forward tilt function by shifting his or her centre of gravity. While bracket 82 is shown mounted in cut-out portion 80 of bracket 54, those skilled in the art will appreciate that bracket 82 could be readily be mounted below bracket 54. In such an embodiment, pins 100 and 104 would be operably coupled to housing 40 by angle brackets extending downwardly from the housing.

In another embodiment of a forward tilt mechanism embodying the subject invention, a variable angle of tilt is achieved by substituting a cam rod for the cylindrical stop rod 104 of Figure 4. Referring to Figure 5, the stop means includes a cam rod 110 having a cam rod portion 112 mounted through slots 96 and 98 with one end of rod portion 110 rotatably mounted in one side wall 60 and the other end protruding through the other side wall 60 and connected to a knob 114 used to manually rotate rod 110, also shown in Figure 1. In this embodiment cam rod portion 112 is spaced from the upper end of slots 96 and 98 in the untilted position so that rotation of rod 110 to vary the tilt angle does not also cause the seat while in the "untilted" position to be automatically tilted. Tab 105 would prevent backward tilting in this embodiment. The tilt angle is varied by rotating cam rod 110 which acts to preselect the distance through which housing 40 may pivot before cam rod portion 112 abuts the lower end of slots 96 and 98. In this way the tilt angle may be manually varied within a range from about 0 to 10 degrees depending on the user's needs or preferences.

In operation a seat base and cushion are secured to top surface 46 of bracket 42 with the front of the seat being located above front end 70 of housing 40, see Figure 1. A user sitting in the chair can recline backwards in known fashion by leaning rearwards so that, looking to Figures 2 and 4, bracket 42 pivots about pivot rod 62 in the direction of arrow A against bias spring 64 thereby causing the user to tilt rearwards. When the user returns to the upright position so that the chair seat is generally horizontal, the spring returns bracket 42 to its resting position with respect to the bracket 54. In order to tilt forward, the user shifts his or her centre of gravity in the forward direction thereby causing housing 40 to pivot about pivot rod 100 in the direction of arrow B until stop rod 104 intercepts the lower ends of slots 96 and 98.

Figures 6-8 illustrate the range of forward tilt motion of the chair seat but with cam rod portion 112 adjusted to give a different tilt angle in Figures 7 and 8.

The decoupling of the forward and backward tilt functions disclosed herein has been illustrated with reference to one specific type of tilt mechanism, but it will be readily understood that the same principle can be applied to any other type of tilt mechanism where it is desirable to have a biased backward tilt and an unbiased forward tilt mechanism.

Further, it will be understood that the forward tilt mechanism disclosed herein may be used with chairs which have no rearward tilt mechanism. Referring to Figures 9 an 10, a forward tilt mechanism absent a rearward tilt mechanism is shown at 120, pins 100' and 110' (or 104) are mounted to a mounting bracket 122 having a top surface 124 which could be coupled to the underside of a seat base. A spindle receiving bracket 82' would be pivotally mounted to pin 100' as discussed above. Bracket 122 is mounted to the underside of a seat base in such a way so that spindle bracket 82' is positioned with respect to the seat in such a way that the user actuates the forward tilt function by shifting his or her centre of gravity.

Therefore,. while the forward tilt mechanism of the present invention has been described ^' and illustrated with respect to preferred and some alternative embodiments, it will be appreciated that numerous variations of these embodiments may be made without departing from the scope of the invention.

Claims

I CLAIM:

1. A tilt mechanism for a chair, comprising: chair spindle receiving means pivotally attachable to the underside of a chair seat for receiving a seat support spindle, wherein, when in use, the seat is movable with respect to the spindle receiving means between a substantially untilted position with respect to the horizontal and a position in which the chair seat is tilted forward at an angle with respect to the horizontal by a user of the chair shifting his centre of gravity forward from a first position, the spindle receiving means mounted at a position with respect to the seat so that the seat returns to the untilted horizontal position by the user either returning his centre of gravity to said first position or by vacating the seat.

2. A tilt mechanism according to claim 1 wherein the spindle receiving means is a bracket having opposed faces each provided with a hole therein, the end of the seat support spindle mountable through said holes, the bracket including opposed sides, a pivot rod mounted through said opposed sides adjacent one end thereof, the pivot rod being operably connectible to the underside of the chair seat, each opposed side provided with an elongate slot, the slots being in alignment and located on the side of the holes opposite from the end of the bracket which is pivotally coupled to the pivot rod, a stop means operably connectible to the chair seat underside, the stop means including a stop rod extending through the aligned slots so that the ambit of pivotal motion of the chair seat with respect to the bracket is defined by the stop rod abutting the ends of said aligned slots.

3. A tilt mechanism according to claim 2 wherein the dimensions of the aligned elongate slots and the diameter of the stop rod are chosen to give a maximum forward tilt angle of about 6 degrees.

4. A tilt mechanism according to claim 2 wherein the stop rod includes a cam rod portion which can be manually rotated so that the angle of tilt can be varied.

5. A tilt mechanism according to claim 4 wherein the tilt angle can be varied between about 0 to about 10 degrees.

6. A chair having a forward tilt mechanism, comprising: a) a chair support base, a chair seat support spindle attached to said support base and extending upwardly therefrom; and b) a chair seat operably coupled to said seat support spindle, said operable coupling comprising a chair spindle receiving means pivotally attachable to the underside of said chair seat for receiving said seat support spindle, the chair seat being., movable with respect to the spindle receiving means between a substantially untilted position with respect to the horizontal and a position in which the chair seat is tilted forward at an angle with respect to the horizontal, wherein the spindle receiving means is located with respect to said seat underside such that the chair seat is tilted forward by the user shifting his centre of gravity forward from a first position, and wherein the seat returns to the substantially untilted position by the user shifing his centre of gravity back to said first position or by the user vacating the seat.

7. A chair according to claim 6 wherein the spindle receiving means is a bracket having opposed faces each provided with a hole therein., the end of the seat support spindle mounted through said holes, the bracket including opposed sides, a pivot rod mounted through said opposed sides adjacent one end thereof, the pivot rod operably coupled to the underside of the chair seat, each opposed side provided with an elongate slot, the slots being in alignment and located on the side of the holes spaced from end of the bracket which is pivotally coupled to the pivot rod, a stop means operably coupled to the chair seat underside, the stop means including a stop rod extending through the aligned slots so that the ambit of pivotal motion of the chair seat with respect to the bracket is defined by the stop rod abutting the ends of said aligned slots.

8. A chair according to claim 7 wherein the stop rod includes a cam rod portion which can be manually rotated so that the angle of tilt can be varied.

9. A chair according to claim 8 wherein the tilt angle can be varied between about 0 to about 10 degrees.

10. In an improved tilt mechanism for a chair, the chair being of the type having a rearward tilt mechanism which includes a housing for enclosing the rearward tilt mechanism, wherein the housing includes a first housing portion to which a chair seat is attachable, and a second housing portion coupled to the first housing portion in such a way that when, in use, as the chair seat is tilted rearwardly, the first housing portion pivots with respect to the second housing portion, the improvement comprising; chair spindle receiving means operably coupled to the second housing portion for receiving a seat support spindle, the chair seat movable with respect to the chair spindle receiving means between a first position in which the chair seat is substantially untilted with respect to the horizontal and a second position in which the chair seat is tilted forward at an angle with respect to the horizontal, wherein the spindle receiving means is operably coupled to said second housing portion at a position such that the chair seat is tilted forward by the user shifting his centre of gravity.

11. An improved tilt mechanism according to claim 10 wherein the second housing portion is provided with a cut¬ out portion, the spindle receiving means including a support bracket pivotally mounted to the second housing portion in said cut-out portion, the bracket provided with attachment means for securely attaching a seat support spindle thereto.

12. An improved tilt mechanism according to claim 11 wherein the support bracket is provided with opposed faces each provided with a hole therein, the end of the seat support spindle being mounted through said holes, the bracket including opposed sides, a pivot rod mounted through said opposed sides adjacent one end thereof, the pivot rod being operably coupled to the second housing portion so that the, second housing portion pivots with respect to the bracket, each opposed side provided with an elongate slot, the slots being in alignment and located on the side of the holes spaced from end of the bracket which is pivotally coupled to the pivot rod, a stop means operably coupled to the chair seat underside, the stop means including a stop rod extending through the aligned slots so that the ambit of pivotal motion of the chair seat with respect to the bracket is defined by the stop rod abutting the ends of said aligned slots.

13. A tilt mechanism according to claim 12 wherein the dimensions of the aligned elongate slots and the diameter of the stop rod are chosen to give a maximum forward tilt angle of about 6 degrees.

14. A tilt mechanism according to claim 12 wherein the stop rod includes a cam rod portion which can be manually rotated so that the angle of tilt can be varied.

15. A tilt mechanism according to claim 14 wherein the tilt angle can be varied between in the range from about 0 to about 10 degrees.

16. A tilt mechanism for a chair offering both forward and rearward tilt functions, comprising: a) a housing enclosing a rearward tilt mechanism, the housing including a first bracket having a top surface and a bottom surface, a chair seat attachable to the top surface of the first bracket, the housing provided with a second bracket pivotally mounted to the first bracket in facing relationship with the bottom surface of the first bracket, the rearward tilt mechanism located adjacent one end of the housing between two facing end portions of the brackets, the second bracket provided with a cut-out portion located adjacent the other end of the second bracket; b) a seat support spindle receiving bracket located in the cut-out portion and pivotally mounted to the second bracket adjacent an end of said spindle receiving bracket closest to said other end of the second bracket; and c) the housing including stop means positioned in the housing so that it is intercepted by the spindle receiving bracket after the housing pivotally moves with respect to the spindle support bracket a predetermined distance, wherein the spindle receiving bracket is pivotally mounted to said second housing portion at a position such that, when in use, the chair seat is tilted forward by the user shifting his centre of gravity until the stop means is intercepted by the spindle receiving bracket wherein the seat is in the forward tilted position.

17. A tilt mechanism according to claim 16 wherein the spindle receiving bracket includes opposed faces each provided with a hole therein, the end of the seat support spindle mounted in said hole, the bracket including opposed sides, each opposed side provided with an elongate slot, the slots being in alignment and located on the side of the hole spaced from end of the spindle receiving bracket which is pivotally coupled to the second bracket, the stop means including a rod attached to the second bracket and extending through the aligned slots so that the ambit of pivotal motion of the housing with respect to the spindle receiving bracket is defined by the rod abutting the ends of said aligned slots.

18. A tilt mechanism according to claim 17 wherein the dimensions of the aligned elongate slots and the diameter of the stop rod are chosen to give a maximum forward tilt angle of about 6 degrees.

19. A tilt mechanism according to claim 17 wherein the rod includes a cam member which can be manually adjusted so that the angle of tilt can be varied.

20. A tilt mechanism according to claim 19 wherein the tilt angle can be varied between about 0 to about 10 degrees.