Apparatus with weight responsive changeable adjusting characteristics

Abstract

A reconfigurable apparatus for seating a user and having: a frame; a seat movable relative to the frame between: a) a first position in which the seat resides with no user sitting on the seat; and b) a loaded position; a back rest with a changeable angular orientation relative to the frame; and an adjusting assembly having a plurality of gears that move relative to each other as an incident of the seat moving from the first position into the loaded position to thereby cause an increase in resistance to changing of the angular orientation of the back rest.

Claims

1. A reconfigurable apparatus for seating a user, the reconfigurable apparatus comprising: a frame; a seat mounted on the frame and movable relative to the frame between: a) a first position in which the seat resides with no user sitting on the seat; and b) a loaded position into which the seat moves from the first position as an incident of a user sitting on the seat; a back rest against which a user sitting on the seat can bear his/her back to produce a leaning force that changes an angular orientation of the back rest relative to the frame, the apparatus configured so that a first leaning force is required to be applied to the back rest to change the angular orientation of the back rest from a starting angular position relative to the frame with no user sitting in the seat; and an adjusting assembly comprising a plurality of gears that cooperate and move relative to each other as an incident of the seat moving from the first position into the loaded position and configured to thereby increase a resistance to changing of the angular orientation of the back rest from the starting angular position, whereby as an incident of a user sitting on the seat a leaning force greater than the first leaning force is required to change the angular position of the back rest from the starting angular position.

2. The reconfigurable apparatus for seating a user according to claim 1 wherein the plurality of gears comprises a first rack gear and first pinion gear, the first rack gear and first pinion gear cooperating with, and movable relative to, each other as an incident of the seat moving from the first position into the loaded position.

3. The reconfigurable apparatus for seating a user according to claim 2 wherein the plurality of gears comprises a second rack gear and a second pinion gear, the second rack gear and second pinion gear cooperating with, and movable relative to, each other as an incident of the seat moving from the first position into the loaded position.

4. The reconfigurable apparatus according to claim 1 wherein the reconfigurable apparatus comprises an elongate spring bar having a length and that resists changing of the angular orientation of the back rest from the starting position by bending against a fulcrum part.

5. The reconfigurable apparatus for seating a user according to claim 4 wherein as an incident of the seat being changed from the first position into the loaded position the fulcrum part is caused to move along the length of the elongate spring bar so as to thereby increase a force required to bend the elongate spring bar about the fulcrum part and as an incident thereof increase the leaning force required to change the angular orientation of the back rest.

6. The reconfigurable apparatus for seating a user according to claim 5 wherein the plurality of gears are configured so that the seat moves a first distance between the first and loaded positions and the fulcrum part moves greater than the first distance along the length of the fulcrum bar in response to a same movement of the seat relative to the frame.

7. The reconfigurable apparatus for seating a user according to claim 1 wherein the back rest is mounted directly to the frame.

8. The reconfigurable apparatus for seating a user according to claim 1 wherein the back rest is mounted directly to the seat.

9. The reconfigurable apparatus for seating a user according to claim 8 wherein the back rest follows movement of the seat as the seat is changed from the first position into the loaded position.

10. The reconfigurable apparatus for seating a user according to claim 8 wherein the back rest is attached to and movable relative to the seat.

11. The reconfigurable apparatus for seating a user according to claim 1 wherein the sitting apparatus comprises a chair.

12. The reconfigurable apparatus for seating a user according to claim 11 wherein the frame comprises wheels that support the chair on a subjacent surface.

13. The reconfigurable apparatus for seating a user according to claim 11 wherein the chair comprises a pair of armrests.

14. The reconfigurable apparatus for seating a user according to claim 11 wherein the chair is a task chair.

15. The reconfigurable apparatus for seating a user according to claim 1 wherein the plurality of gears comprises first and second gears that each turns around an axis and the first and second gears have different diameters.

16. The reconfigurable apparatus for seating a user according to claim 15 wherein the first and second gears turn around different axes.

17. The reconfigurable apparatus for seating a user according to claim 15 wherein the first and second gears turn around a same axis.

18. The reconfigurable apparatus for seating a user according to claim 1 wherein the reconfigurable apparatus comprises at least one spring bar that is bent under forces applied by a user to the reconfigurable apparatus to resist reconfiguration of a part of the reconfigurable apparatus.

19. The reconfigurable apparatus for seating a user according to claim 18 wherein the at least one spring bar comprises a plurality of spring bars.

20. The reconfigurable apparatus for seating a user according to claim 19 wherein at least one of the spring bars comprises an elongate spring bar with a length and the elongate spring bar resists reconfiguration of the reconfigurable apparatus by being bent transversely to the length of the elongate spring bar.

21. The reconfigurable apparatus for seating a user according to claim 3 wherein the reconfigurable apparatus comprises an elongate spring bar having a length and that resists changing of the angular orientation of the back, rest from the starting position by bending against a fulcrum part, the seat moves a first distance between the first and loaded positions, and the first and second rack and pinion gears are configured so that as an incident of the seat moving from the first position into the loaded position there is relative movement of the elongate spring bar and fulcrum along the length of the elongate spring bar a distance different than the first distance.

22. The reconfigurable apparatus for seating a user according to claim 4 wherein the seat moves a first distance between the first and loaded positions and the plurality of gears comprises first and second gear pairs configured so that as an incident of the seat moving from the first position into the loaded position there is relative movement of the elongate spring bar and fulcrum along the length of the elongate spring bar a distance different than the first distance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic representation of a reconfigurable apparatus, according to the present invention;

(2) FIG. 2 is a side elevation view of a task chair, that is one representative form of apparatus as shown in FIG. 1, and incorporating an adjusting assembly according to the present invention;

(3) FIG. 3 is a partially schematic representation of one specific form of adjusting assembly, integrated into the apparatus in FIGS. 1 and 2;

(4) FIG. 4 is a fragmentary view of a part of the adjusting assembly in FIG. 3, which utilizes a leaf spring, and from a different perspective;

(5) FIG. 5 is an enlarged, fragmentary view of a modified form of a leaf spring utilized on the apparatus in FIGS. 3 and 4;

(6) FIG. 6 is an enlarged, fragmentary, elevation view of a linkage, modified from a corresponding linkage as used on the apparatus in FIGS. 3 and 4;

(7) FIGS. 7-16 are partially schematic representations of apparatus incorporating different forms of adjusting assemblies, according to the invention;

(8) FIG. 17 is a schematic representation of a further modified form of reconfigurable apparatus, according to the present invention; and

(9) FIG. 18 is a schematic representation of adjusting assemblies, according to the invention, acting between separate components on a frame.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(10) In FIG. 1, a reconfigurable apparatus, according to the present invention, is shown in schematic form at 10. The apparatus 10 consists of a frame 12 and at least a first component 14 on the frame 12 upon which a force is applied in a first manner in using the apparatus 10 for its intended purpose.

(11) At least a second component 16 is provided on the frame 12 and is movable relative to the at least first component and/or the frame 12. A force can be applied in a second manner upon the at least second component to reconfigure the apparatus 10 by moving the at least second component 16 relative to the at least first component and/or the frame 12.

(12) An adjusting assembly 18 cooperates between the at least first component 14 and the at least second component 16 and is configured so that, as an incident of the force being applied in the first manner changing, the force applied in the second manner required to reconfigure the apparatus 10 changes.

(13) The adjusting assembly 18 includes a spring assembly 19. The spring assembly 19 is configured to exert a force that resists movement of the at least second component 16 that varies as a magnitude of the force applied in the first manner varies.

(14) The generic showing of the apparatus 10 is intended to encompass a wide range of different products and different applications. The inventive concepts can be used in virtually any system or apparatus wherein its normal intended use requires the application of a force on a first component and wherein that force on the first component impacts a force required to be applied to a second component to reconfigure the apparatus as contemplated during use.

(15) While not intended to be limiting, the detailed description herein will be focused upon furniture and, more particularly, a chair construction. This application of the inventive concepts is intended to be exemplary in nature only and should not be viewed as limiting the inventive concepts to the specific type of apparatus described in detail herein. Further, the schematic showing in FIG. 1 is intended to encompass not only a wide range of different systems/apparatus, but different forms of components and their interaction for each such system/apparatus.

(16) For example, interlocking toothed components are described, in exemplary forms below. The invention contemplates not only different types of toothed components, such as gears, differential gears, epicyclic gears, rack and pinion arrangements, etc., but also virtually an unlimited number of different interengaging components, such as sprockets and chains, pulleys and cables, mechanisms using levers, pistons, different types of linkages, etc.

(17) In FIG. 2, one exemplary apparatus 10 is shown in the form of a task chair, in this case without armrests. Of course, armrests might be incorporated and might also have parts thereof movable in different manners depending upon the weight of the user, as hereinafter explained.

(18) The chair 10 has a wheeled frame 12 with a vertically extending pedestal assembly 20. The first component 14 is in the form of a conventional-type seat with an upwardly facing user support surface 22. In this case, the aforementioned force applied in the first manner is the weight of the user exerted downwardly on the support surface 22 as he/she sits on the chair 10.

(19) A corresponding second component 16 is in the form of a back rest against which a seated user leans to exert the aforementioned force in the second manner to reconfigure the chair 10. That is, the back rest moves relative to the frame 12 and first component 14, as the user leans back and forth while seated, generally in a manner as indicated by the double-headed arrow 23.

(20) The adjusting assembly 18, as shown schematically in FIG. 2, acts between the first component/seat 14 and second component/back rest 16 directly and/or through the frame 12. The adjusting assembly 18 may be added to the frame 12 by attachment thereto, virtually anywhere thereon, or integrated thereinto, as by being constructed within a hollow 24 on the pedestal assembly 20.

(21) The chair 10 may incorporate one or more adjusting features other than one that permits reconfiguration by changing the angle of the second component/back rest 16. The adjusting assembly 18 may be integrated into the mechanisms associated with these other features. Alternatively, the other features may operate without effect by the adjusting assembly 18.

(22) For purposes of simplicity, the second component/back rest 16 will be shown as repositionable relative to the first component/seat 14 to reconfigure the chair 10 by movement of the second component/back rest 16 relative to the first component/seat 14 and frame 12 around a pivot axis 26. This particular connection should not be viewed as limiting.

(23) Exemplary specific forms of the adjusting assembly 18 will now be described. As noted above, virtually an unlimited number of different variations of adjusting assembly are contemplated within the generic showing of FIGS. 1 and 2. These specific forms are exemplary in nature only. These particular mechanisms will also be described with respect to the apparatus in the form of a chair as shown in FIG. 2. Again, the particular nature of the apparatus is not limited to a chair or furniture, although it has particular applicability in this category of product.

(24) In FIGS. 3 and 4, the first component/seat 14 (hereinafter referred to only as the representative chair seat 14) is integrated into a support 28 that has a depending post 30 that is slidable guidingly vertically, as indicated by the double-headed arrow 32, in a guide channel 34 on the frame 12. A biasing assembly, shown in one exemplary form as a coil spring 33, normally biasably urges the seat 14 upwardly relative to the frame 12.

(25) A generally U-shaped member 36 has one leg 38 of the U mounted on a frame part 40. The other leg 42 of the U has an offset bracing end 44.

(26) For purposes of simplicity, the support 28 and member 36 can be considered to be part of the frame 12 and/or the adjusting assembly 18. Similarly, the component 58 can be considered to be part of the back rest 16 and/or the adjusting assembly 18.

(27) The spring assembly 19 in this embodiment is in the form of a leaf spring. The leaf spring 19 has an elongate body 46 with a length L between spaced ends 48, 50, a width W, and a thickness T.

(28) The leaf spring end 19 is anchored in the member 36 to project in cantilever fashion vertically upwardly therefrom. In this embodiment, the body 46 of the leaf spring 19 is preloaded so that it naturally assumes the dotted line shape and position.

(29) The bracing end 44 of the member 36 is bifurcated, as seen in FIG. 4, with spaced edges 52 (one shown) at the extremity of the bracing end 44 engageable with one surface 54 of the leaf spring body 46 to maintain the body 46 in the straight vertical orientation, as shown in FIG. 3.

(30) A part of the second component/back rest 16 (hereafter referred to only as the representative chair back rest 16) is connected to the support 28 for movement relative thereto around the axis 26 as seen in FIG. 2. As a user situated on the seat 14 leans against the back rest 16, a force is generated as shown by the arrow 56 on the back rest component 58 that tends to pivot the component 58 in the direction of the arrow 60 around the axis 26.

(31) The component 58 is configured so that an edge 61 on a cantilevered part 62 thereof bears against the leaf spring surface 54. In the depicted state, this produces a force upon the leaf spring body 46, at a location A along the length of the body 46, that tends to bend the body 46 in the direction of the arrow 64 around a fulcrum location at 66 where the body 46 projects away from the part of the member 36 in which it is anchored. The leaf spring 19 thus biasably resists movement of the component 58, and the back rest 16 of which the component 58 is a part, with a first force.

(32) The configuration in FIG. 3, while it could show a starting state without any force application on the seat 14, is also representative of the overall state of the apparatus 10 with an individual of a first weight seated thereon. This is an equilibrium position for the chair 10 resulting from the balancing of the user's weight and the upward biasing force generated by the spring 33 acting between the frame 12 and the seat 14 through the support 28.

(33) In the event that an individual of greater weight assumes a sitting position on the seat 14, the support 28 and component 58 will translate further downwardly against the force of the spring 33, which causes the edge 61 on the back rest component 58 to bear upon the leaf spring 19 at a location below the location A. As a result, a shorter moment arm is established between the location where the edge 61 on the part 62 contacts the surface 54 and the fulcrum location at 66. Thus, the leaf spring 19 has an effectively shorter length, whereby a greater force is required to be applied to the leaf spring 19 to effect bending thereof as would in turn allow movement of the back rest 16 to reconfigure the chair 10.

(34) To stabilize the support 28, a depending arm 70 thereon connects to the frame part 40 through a link 72. One link end 74 moves about an axis 76 that is fixed relative to the frame part 40. The other link end 78 pivotally connects to the arm 70 for movement about an axis 80.

(35) The bifurcated configuration of the leg 42 allows the part 62 on the component 58 to move in an opening 82 through the region at the offset bracing end 44 so that the member 36 does not interfere with the back rest component 58 as the back rest component 58 lowers under increasing user weight.

(36) Accordingly, an increase in the weight of a user causes the leaf spring 19 to produce a greater resistance to movement of the back rest 16 relative to the frame 12. As a result, the chair is self-adjusting. The parts thereof can be engineered so that a desired relationship between the user's weight and the force required to move the back rest 16 are appropriately established.

(37) In designing the chair 10 using a leaf spring component, the leaf spring body 46 may have a uniform cross-sectional shape as viewed orthogonally to its length. Alternatively, this shape may be non-uniform over at least a portion of its length. For example, as shown for a portion of the length of a modified form of body 46a, as shown in FIG. 5, the cross-sectional area varies progressively.

(38) Tapering the cross-sectional area of the leaf spring over its length may allow further tuning of performance. Thickened regions may be provided to produce larger resistance forces for users at the higher weight end of the functional range.

(39) The leaf spring material may be metal, plastic, a composite, etc. The leaf spring may be straight, curved, with changing cross-sectional shapes, etc. Changing shapes, pre-loading, changing dimensions, etc., are just examples of options that might be practiced to design and tune the adjusting assemblies so that they adapt more appropriately to users throughout a workable user weight range.

(40) In a still further modified form of the structure in FIG. 3, as shown in FIG. 6, the link 72a, corresponding to the link 72, can be connected to the frame 12 for pivoting movement about an axis 84 between its ends 74a, 78a. Accordingly, as the arm 70a moves downwardly under increasing user weight, link 72a pivots around the axis 84 so that the member 36a simultaneously moves upwardly. Thus, for each incremental movement of the seat 14 downwardly, there is a greater movement of the edge 61 on the part 62 toward the fulcrum location 66 for the leaf spring 19 than occurs with the design in FIGS. 3 and 4.

(41) In FIG. 7, a modified form of chair is shown at 10, with elements corresponding to those in FIGS. 3 and 4 identified with like reference numerals and a designation.

(42) The chair 10 has a back rest component 58 that acts against a leaf spring 19 that is anchored in a component 36.

(43) In this embodiment, the leaf spring body 46 is mounted at a slight angle to vertical. Accordingly, the part 62 of the component 58 tends to bind more with the leaf spring 19 as it slides downwardly thereagainst under increasing user weight. This binding creates frictional forces that augment the upward balancing force produced by the spring 33.

(44) Additionally, the chair 10 utilizes cooperating toothed elements 86, 88, 90 that interact to cause movement of the frame part 40, arm 70 and leg 38 relative to each other and the frame part 40 that replicates the relative movement that occurs with corresponding elements in the embodiment shown in FIGS. 3 and 4. The toothed element 88 is in the form of a differential pinion that turns around an axis 92. Larger and smaller diameter toothed portions 94, 96, respectively, engage toothed racks 98, 100, respectively on the leg 38 and arm 70. Turning of the toothed element 88 in the direction of the arrow 102 under increasing user weight causes simultaneous upward movement of the member 36 and downward movement of the support 28.

(45) In FIG. 8, a further modified form of chair, according to the present invention, is shown at 10. The chair 10 incorporates a back rest component 58 that interacts with a leaf spring 19 and leg 42 in the same way that the corresponding components interact on the chair 10 in FIGS. 3 and 4.

(46) Further, the chair 10 incorporates toothed elements 86, 88, 90 which function essentially in the same manner as the corresponding components on the chair 10 in FIG. 7. The primary difference between these embodiments is that the leg 38 has a curved shape that moves in a complementarily-curved channel 104 on the frame part 40. Whereas the support 28 associated with the seat 14 and member 36 move relative to each other in parallel, straight paths, the member 36 moves in a curved path, as dictated by the curvature of the leg 38 and cooperating channel 104. This curvature nominally matches the curved shape of the leaf spring 19 which is pre-loaded from the dotted line position to the operative, solid line position in FIG. 8. Accordingly, the relative movement of the member 36 and support 28 causes the part 62 that engages the leaf spring 19 to generally follow the pre-loaded curvature of the leaf spring 19.

(47) In a further modified form of chair, as shown at 10 in FIG. 9, the basic construction of FIGS. 3 and 7 is utilized with the exception that the leaf spring 19 is fixedly mounted to the component 58 and acts against the member 36, i.e., this component arrangement is reversed from that in the earlier embodiments. The leaf spring 19 is pre-loaded from the dotted line position into the solid line position which is maintained by the abutment thereof to the member 36.

(48) In FIGS. 10 and 11, a further modified form of chair, according to the invention, is shown at 10.sup.4. In this embodiment, multiple leaf springs 19a.sup.4, 19b.sup.4, 19c.sup.4, 19d.sup.4 are utilized, each with an end anchored in a block 105.

(49) In this embodiment, the post 30.sup.40 has a toothed rack 100.sup.4 that cooperates with a toothed, differential pinion element 88.sup.4, that cooperates in turn with a toothed rack 98.sup.4 making up part of a toothed element 86.sup.4 on a member 36.sup.4.

(50) Downward movement of the post 30.sup.4 under the weight applied to the seat 14 causes the toothed rack 100.sup.4 and toothed element 88.sup.4, and separately the toothed elements 88.sup.4, 86.sup.4, to interact to translate the member 36.sup.4 in the direction of the arrow 106.

(51) As the weight on the seat 14 is increased, the member 36.sup.4 will move continuously in the direction of the arrow 106 to successively engage free ends of angled extensions 108a, 108b, 108c at the ends of leaf springs 19a.sup.4, 19b.sup.4, 19c.sup.4, successively. The extensions 108a, 108b, 108c and one surface 110 on the leaf spring 19d.sup.4 reside in a reference plane P. As user applied weight increases, a surface 112 on the member 36.sup.4 moves along this plane P to successively engage the extensions 108a, 108b, 108c and eventually the surface 110, whereby the surface 112 defines separate fulcrum locations, corresponding to the fulcrum location 66, for the free ends of the leaf springs 19a.sup.4, 19b.sup.4, 19c.sup.4, 19d.sup.4. In other words, the leaf springs 19a.sup.4, 19b.sup.4, 19c.sup.4, 19d.sup.4 are successively operatively engaged under increasing user weight. As a result, the resistance force to the applied leaning force on the back rest 18 in the direction of the arrow 114 is generated by some or all of the leaf springs 19a.sup.4, 19b.sup.4, 19c.sup.4, 19d.sup.4 as they are borne against the surface 112 under the user leaning force.

(52) It is important to point out that the rack and pinion components are not restricted to any specific orientation. The cooperating rack and pinion components may be oriented in virtually any orientation that can be adapted to cause movement of the associated parts in the same manner.

(53) Further, one or all of the leaf springs 19a.sup.4, 19b.sup.4, 19c.sup.4, 19d.sup.4 could be pre-loaded or in curved tracks.

(54) In an alternative form of the basic structure in FIGS. 10 and 11, as shown for the chair 10.sup.5 in FIGS. 12 and 13, the member 36.sup.5 vertically advanced, or advanced in another direction, is caused to interact with some, or all, of a plurality, and in this case three, leaf springs 19a.sup.5, 19b.sup.5, 19c.sup.5, which are arranged to be substantially coplanar, as opposed to stacked as the leaf springs 19a.sup.4, 19b.sup.4, 19c.sup.4, 19d.sup.4 are on the chair 10.sup.4.

(55) Under an increasing user weight on the seat 14, a surface 112.sup.5 on the member 36.sup.5 engages successively against surfaces 116a.sup.5, 116b.sup.5, 116c.sup.5. As shown in FIG. 12, the particular exemplary weight causes engagement of the surface 112.sup.5 with only two of the leaf springs 19a.sup.5, 19b.sup.5.

(56) The leaning force on the back rest 18 is applied on an actuator 118 in a direction into the page, as indicated by the X at 120. Resistance to the leaning force is generated in the same manner for the chair 10.sup.5 as for the chair 10.sup.4 but with the different arrangement of leaf springs.

(57) In an alternative form, each of the leaf springs in FIGS. 12 and 13 might be substituted for by coil springs, compression/tension springs, or a torsion rod of the type described in an additional embodiment below. One or more springs might be utilized. More springs allow for finer control. Each spring can be individually tuned.

(58) In FIG. 14, a further modified form of chair, according to the invention, is shown at 10.sup.6. A post 30.sup.6 has a toothed rack 100.sup.6 that cooperates with a differential pinion/toothed element 88.sup.6. The toothed element 88.sup.6 moves together with a component 58.sup.6 that is part of the back rest 16 or otherwise moves in response to movement thereof. The component 58.sup.6 is mounted for pivoting movement relative to a frame part 122 around an axis 124 as the post 30.sup.6 raises and lowers as different weight forces are applied to and removed from the seat 14.

(59) The leaning force on the back rest 16 is applied to an arm 126 on the component 58.sup.6 in the direction of the arrow 128.

(60) The frame part 122 has a U shape with spaced legs 130, 132. The component 58.sup.6 is mounted on the leg 130.

(61) The toothed element 88.sup.6 cooperates with a separate toothed element 134 that moves guidingly in a channel 136 on the component 58.sup.6. In this embodiment, the toothed element 134 and cooperating channel 136 have a curved shape so that the toothed element 134 is movable guidingly in an arcuate path. A row of teeth 138 on one side of the toothed element 134 engage teeth 140 on the toothed element 88.sup.6 so that the toothed element 134 moves back and forth within the channel 136 as the toothed element 88.sup.6 is rotated in opposite directions around its axis 124.

(62) The adjusting assembly 18.sup.6 in this embodiment consists of an elongate spring assembly 19.sup.6, in this particular embodiment shown as a coil spring under tension. The spring 19.sup.6 is connected between an end location at 144 on the toothed element 134 and the leg 132 on the frame part 122.

(63) As a user sits on the seat 14, without leaning against the back rest 16, the post 30.sup.6 moves against the force of the spring 33.sup.6 downwardly, thereby turning the toothed element 88.sup.6 in the direction of the arrow 146, which causes the toothed element 134 to move in the direction of the arrow 148 in the channel 136. The precise position of the toothed element 134 in the channel 136 is dictated by the weight of the user.

(64) Once the user is seated and leans back against the back rest 16, separate teeth 150, 152, on the toothed element 134 and component 58.sup.6, within the channel 136, engage, thereby to fix the position of the toothed element 134 within the channel 136.

(65) Under an applied leaning force in the direction of the arrow 128 on the arm 126, the component 58.sup.6, and the associated back rest 16, tend to pivot around the axis 124, which is resisted by the force in the spring 142. Because the distance between the axis 124 and end location 144 where the resistant spring force is applied is increased with increasing weight of a user, the resistant force generated by the coil spring 19.sup.6 is likewise increased.

(66) The chair 10.sup.7 in FIG. 15 operates on the same basic principles as the chair 10.sup.6 in FIG. 14.

(67) More particularly, a toothed element 134.sup.7 moves in a channel 136.sup.7 having an arcuate shape. A coil spring 19.sup.7 connects between the toothed element 134.sup.7 and a leg 132.sup.7 on a U-shaped frame part 122.sup.7.

(68) The primary difference between the structure in FIG. 15, compared to that in FIG. 14, is that the toothed element 134.sup.7 is part of, and moves with, an elongate component 154 that is pivoted about an axis 156 that is the approximate location at which the spring 19.sup.7 connects to the leg 132.sup.7. The component 154 has a curved edge 158 with a constant radius R centered on the axis 156. That edge 158 has teeth 160 which mesh with teeth 162 on a post 30.sup.7 that has a toothed rack 100.sup.6 where the teeth 162 are located.

(69) Increased weight of a user on the seat 14 pivots the component 154 in the direction of the arrow 164 around the axis 156 to move the toothed element 134.sup.7 in the direction of the arrow 166 in the channel 136.sup.7. In so doing, the distance between the spring mount location at 144.sup.7 on the toothed element 134.sup.7 and the pivot axis 124.sup.7 for the component 58.sup.7 increases, thereby to cause an increase in the resistance to tilting of the back rest 16 in the same manner as occurs with the chair 10.sup.6.

(70) In FIG. 16, a further modified form of chair is shown at 10.sup.8 wherein the spring assembly 19.sup.8 includes an elongate torsion component 168 with a lengthwise axis 170. The adjusting assembly 18.sup.8 further includes an actuating component 172 that has a portion 174 keyed to the periphery of the torsion component 168 to move slidingly axially therealong in the same angular orientation. With the torsion component 168 fixed in relationship to the frame 12.sup.8, a user's weight on the seat 14 causes movement of the actuating component 172 through cooperation between a toothed rack 176 thereon and intermediate input structure 178 of suitable construction. Increased weight on the seat 14 causes the actuating component 172 to shift closer to a base 180 of the torsion component 168 closer to where it is anchored to the frame 12.sup.8.

(71) A leaning force on the back rest 16 is applied to the torsion component generally in the direction of the arrow 182, tending to turn the torsion component 168 around the axis 170. For the back rest 16 to reposition, the torsion component 168 must be twisted around the axis 170. This twisting action is resisted to a greater degree with the actuating component 172 closer to the base 180 under a heavier user weight.

(72) On the other hand, with the actuating component 172 shifted towards its free end 184, as occurs with a lighter user, the torsion component 168 can be more readily twisted about its length and the axis 170.

(73) In FIG. 17, a still further modified form of chair, according to the invention, is shown at 10.sup.9 with an adjusting assembly 18.sup.9 cooperating between a seat 14 and back rest 16. A spring assembly 19.sup.9 is mounted to a frame 12.sup.9 and consists of separate leaf springs with bodies 46.sup.9 each with spaced ends supported by blocks 186, 188 on the frame 12.sup.9. With this arrangement, the bodies 46.sup.9 and blocks 186, 188 cooperatively extend around an opening 190 with a width W.

(74) An elongate, wedge-shaped actuating component 192 with a uniform width W1, slightly less than the width W, extends through the opening 190.

(75) A toothed rack 194 is provided on the actuating component 192 and moves therewith. In response to a weight force being applied to the seat 14, and through an appropriate force transfer structure 196, the toothed rack 194 and actuating component 192 are shifted in the direction of the arrow 198.

(76) By reason of the wedge shape, the actuating component 192 has oppositely facing actuating surfaces S1, S2, each with one dimension D1 at one end and a larger dimension D2 at its opposite end, that abut to, or reside adjacent to, facing surfaces S3, S4, respectively, on the bodies 46.sup.9. As the actuating component 192 shifts in the direction of the arrow 198, a progressively larger area of the surfaces S1, S2 confronts the leaf spring bodies 46.sup.9.

(77) The back rest 16 imparts a force to the actuating component 192 through a suitable force transfer structure at 202 tending to turn the actuating component 192 around an axis 204.

(78) Accordingly, a user leaning force generates a force on the actuating component 192 that bears the surfaces S1, S2 simultaneously against the surfaces S3, S4 of the leaf spring bodies 46.sup.9 between the spaced supported ends. The larger the area of the surfaces S1, S2 in contact with the bodies 46.sup.9, the more resistant the bodies 46.sup.9 are to deformation. This translates into a greater resistance to the repositioning of the back rest 16 for a larger weight application on the seat 14.

(79) Further, as the actuating component 192 turns around the axis 204, the force transfer between the actuating component 192 and bodies 46.sup.9 occurs primarily at corners C1 C2, C3, C4 of the actuating component 192, which bear against reinforced and thus more rigid parts of the bodies 46.sup.9 adjacent to the blocks 186, 188 as more user weight is applied. Thus, greater resistance to back rest movement results.

(80) In a still further alternative form, as shown in FIG. 18, multiple adjusting assemblies 18 are utilized between a cooperating first components)/seat 14 and second component(s)/back rest 16 on a frame 12.

(81) Ideally, the apparatus/chair 10 will adapt to users weighing as much as 350 pounds, or more. While one spring assembly might be designed for a total desired weight range to be accommodated, two or more spring assemblies might be utilized and their function and operation coordinated.

(82) Further, different spring assemblies might be utilized with coordinated operation. For example, one spring assembly may cover a range of 30-175 pounds with a second spring assembly operational for user weights in the range of 175-350 pounds. More springs/spring assemblies might be added to further split up the weight ranges.

(83) The spring assemblies may be designed in relationship to seat movement. For example, one spring assembly may be operational for 0-0.5 of seat movement with a separate spring assembly operational for seat movement of 0.5-1, where 1 is the seat movement for the maximum weight for which the apparatus is designed.

(84) The examples herein of spring assembly/spring construction should not be viewed as limiting. Different spring types and combinations are contemplated. For example, the springs may be curved, coiled with different turn diameter and rise, hybrid shapes, concentric arrangements, etc. Coil springs, or the like, may produce forces under either compression or tension.

(85) The foregoing disclosure of specific embodiments is intended to be illustrative of the broad concepts comprehended by the invention.