Patent Application
20130099534
Not Applicable.
Not Applicable.
1. Field of Invention
The present invention relates generally to the field of moveable and stackable seating. More specifically, this invention relates to stackable chairs having a self-adjustable back support with an improved back spring.
2. Description of the Related Art
Prior chairs having a flexible backrest frame have provided frame members with spring members connected internal of seat tube members for control of movement of the backrest frame of the chair. A typical flexible backrest is illustrated in U.S. Pat. No. 5,039,163, issued to Tolleson, which discloses a chair including depending leg members and a hollow support frame having members with open ends terminating beneath the seat assembly of the chair. The chair includes a pair of hollow backrest frame members having open frame ends extending beneath the seat assembly for alignment with respective open ends of the support frame members. Each open end of the respective frame members includes at least one flexible spring member inserted therein. Prior configurations of spring members allow insertion of opposed spring member ends into opposed and aligned open frame ends, with each spring member being aligned with the frame ends and extended to fill any gap between the respective back frame members and support frame members. Therefore, replacement of the spring member required full disassembly of the chair frame and removal of each inserted spring member end. In order to prevent each spring element from excessive flexing during reclining movements of the chair backrest, the spring member ends have been typically enclosed by pairs of U-shaped brackets of metal that limit the range of angular movement of each enclosed spring member, thereby limiting the reclining movements of the chair backrest. Additional pairs of spring members and U-shaped brackets have been required to be added for rigorous use. The additional pairs of spring members are typically positioned parallel to each first set of spring members with associated enclosure by U-shaped brackets of greater width or depth, thereby requiring an increased width or depth of the support frame members to accommodate the additional spring members and brackets.
Another example of a prior art chair having a flexible backrest frame is illustrated in U.S. Pat. No. 6,896,327, issued to Barile, which discloses a stackable chair with a seat assembly and flexible back support having a seat spring system attached therebetween. The seat assembly includes seat sides having spaced apart rear portions. The back support includes lower ends curved forwardly and disposed in registry with and separated by right and left gaps from respective seat side rear portions. Right and left spring members are disposed inwardly adjacent to bridge each gap. Each spring member includes forward ends connected to respective right and left front support members extended inbound from respective seat sides, and includes rear ends connected to opposed ends of a frame rear cross-member. The spring members allow limited reclining movement of the back frame. A limit to excessive forward movement of the back support is provided by pairs of fixation plates positioned in aligned and abutting relationship on upper surfaces of each respective forward and rear ends of each spring member.
The prior art leaves a void for a stackable chair with a flexible back support frame employing a spring assembly attached directly to the exterior of the back support frame and seat assembly, thus eliminating additional cross structures or spring support members.
The present invention, in some of its various embodiments, comprises a flexible back support frame mechanism for a stackable chair. The flexible back support frame mechanism includes an improved spring system designed to allow reclining movement of a back support frame while denying excessive forward movement of a back support relative to a seat assembly. The seat assembly includes right and left seat sides having spaced-apart rear portions. Right and left pairs of front and rear leg members are attached outboard of respective right and left seat sides, with each pair of leg members extended in spaced apart orientation to allow stacking with like-configured chair frames.
The back support frame includes frame lower ends curved forwardly and positioned in registry with and spaced apart by a gap separation from the rear portions of the seat assembly. Right and left spring members are superposed over each gap separation, with the rear end of each spring member secured in a substantial surface-to-surface contact relationship to the frame lower ends. Each spring member is extended a sufficient length to position a front end forward of each gap separation being secured in a substantial surface-to-surface contact relationship to respective right and left seat sides. This improved spring system dispenses with the need for additional spring support components that were previously required.
During reclining movement of the back support frame, the spring member rear ends are pivotably flexed downwardly to a flexed position. Each spring member is capable of repetitive flexing and includes an inherent bias to rebound to a non-flexed position, thereby returning the back support to a substantially upright position when not reclined by a seat occupant.
The above-mentioned and additional features of the invention will become more clearly understood from the following detailed description of the invention read together with the drawings in which:
A flexible back mechanism for stackable chairs is disclosed incorporating various features of the present invention for a stackable chair 10 as illustrated in
For support of a removable seat cushion 90, the seat assembly 12 includes a front seat member 14 joined at opposed ends to a right seat member 16 and a left seat member 18. The right and left seat members 16, 18 extend rearward to right and left rear portions 16′, 18′ (see
The seat assembly 12 is supported at a typical seating height above a supporting surface by a pair of right and left leg member units 22, 30 utilizing right front 24 and rear 26 legs, and left front 32 and rear 34 legs extending downwardly at respective forward and rearward angles. Each leg member unit 22, 30 includes an upper leg member support 22′, 30′ that is disposed in a substantially horizontal orientation parallel with, and joined outboard to the respective outer surfaces of the right and left seat members 16, 18.
The outboard positioning of the right and left leg member units 22, 30 facilitate generally vertical stacking of the chair 10 with like-configured chairs having similarly positioned leg member units disposed outboard of each seat assembly 12. In order to improve stability of the leg member units 22, 30, the front right and left legs 24, 32 can have an upper leg cross member 40 extended between the front legs 24, 32, and positioned below the front portions of respective right and left seat members 16, 18. The front legs 24, 32 can be angled laterally and outwardly to provide a lower leg width separation 40″ greater than an upper leg width separation 40′ to improve stability of the chair 10 (see
Additional structural rigidity for the leg member units 22, 30 can be provided by a right lateral brace 28, and a left lateral brace 36, with each brace being extended between respective front and rear legs (see
A back support frame 50 is positioned to extend generally upright from the rear portions 16′, 18′ of the right and left seat members 16, 18. The back support frame 50 includes an upper portion 52 joined at opposed ends to right and left frame side members 54, 56 which are spaced apart by a sufficient width to accept a back support cushion 92 detachably connectable thereon (see
As illustrated in
In order to provide a back support frame 50 that repetitively reclines and rebounds to a generally vertical position relative to the seat assembly 12, the opposed ends of each spring member 64 of spring units 62 are connected to respective bottom surfaces of the lower ends of the back support 50 and rear portions of the seat assembly 12. One skilled in the art will recognize that alternative positions of attachment can also be achieved. For instance, the spring members 64 can be connected to respective top surfaces of the lower ends of the back support 54′, 56′ and rear portions of the seat assembly 16′, 18′ without deviating from the present general inventive concept. Each spring member 64 includes a substantially planar and elongated body member having an adequate length to superpose respective left and right gap separations 46, 48 and overlap the back frame lower ends 54′, 56′ and respective rear seat portions 16′, 18′.
One configuration of the spring member 64 includes a length in a range of about three inches to about four inches, having a forward portion 64″ and a rear portion 64″′ (see
The spring member material is preferably biased to return to a substantially horizontal, non-flexed position 80 for approximately 150,000 or more repetitions without failure. One embodiment of the spring member 64 includes generally rectangular exterior dimensions, a rectangular cross-section, and generally planar upper and lower surfaces to provide a compact cross sectional outline while maintaining the desired stiffness over the expected life of the stackable chair 10. One skilled in the art will recognize that alternative cross-sectional outlines can be utilized such as an elongated spring member having a flattened oval cross-section, with generally planar upper and lower surfaces. Each spring member rear portion 64″′ is positioned to rotate downwardly during flexing to a flexed position 82 (see
To accommodate the spring units 62, the right and left seat member rear portions 16′, 18′ each contain a hollow cavity 16″, 18″ (see
Each solid support insert 70, 72 is further designed to provide structural support for each seat assembly 12 and back frame 50 member. Referring to
Additionally, superposed underneath each spring member front portion 64″ and rear portion 64″, and also penetrated by removable connectors 78, is a square washer 66 to facilitate receiving and securing the removable connectors 78 (see
One of skill in the art will recognize that other objects can be interposed between the spring member 64 and the seat member rear portions 16′, 18′ and back support frame lower ends 54′, 56′. For instance, an object having similar dimensions to the square washers 66 can be interposed between each spring member portion 64″, 64′″ and the seat member rear portions 16′, 18′ and back support frame lower ends 54′, 56′ and not compromise the spirit of the present general inventive concept. The spring member 64 will still be overlaid in a substantial surface-to-surface contact relationship with the seat member rear portions 16′, 18′ and back support frame lower ends 54′, 56′. Likewise, interposing a flexible component that spans substantially the length of the spring member 64 can also be included, as long as such component is flexible to facilitate flexing of the spring member 64 and reclining of the back support frame 50.
A back frame stop mechanism can be incorporated to prevent excessive backwards flexing 82 of the back support frame 50. A rear leg restraint bar 38 is extended to join at opposed ends 38′, 38″ between upper portions of the rear legs 26, 34, as illustrated in
A right stop guard 86 and a left stop guard 88 are attached to the lower surfaces of respective right and left frame lower ends 54′, 56′. The stop guards 86, 88 can be composed of a high density plastic material, a molded polypropylene material, other similar synthetic polymers or a rubber material. Each stop guard 86, 88 is positioned on lower surfaces of respective frame lower ends 54′, 56′ to allow contact by each stop guard 86, 88 against the upper surface of the rear restraint bar 38, 138 when the back frame sides 54, 56 are moved rearward 82 by force applied against the back support frame 50. The stop guards 86, 88 are shaped to extend downwardly about a half-inch from the lower surfaces of the right and left frame lower ends 54′, 56′, with preferably an inverted “U” shaped configuration to provide an encircling contact by each stop guard with the rear restraint bar 38, 138 as the right and left frame lower ends 54′, 56′ are moved downwardly. Alternate shapes and thicknesses can be selected for the stop guards in order to limit the maximum downwards movement of the respective right and left frame lower ends 54′, 56′ to about a half-inch of motion. Resulting reclining of the back support frame 50 and downwards flexing of the spring member rear portion 64″′ is limited to about a half-inch. One skilled in the art will readily recognize that the shape of the stop guards 86, 88, the position of the rear restraint bar 38, 138 and the range of extension below the frame lower ends 54′, 56′ can be altered to provide for greater or lesser reclining movement 82 of the back support frame 50. The stop members 86, 88 prevent excessive backwards reclining of the back support frame 50, thereby limiting the flexing motion of each spring member 64 in order to minimize breakage or fracture of either spring member 64.
A forward stop mechanism is provided by the improved spring member 64. The improved spring member is biased to return to non-flexed position 80 after reclining. Whereas the weight of an occupant will provide sufficient force to flex the spring member 64 and facilitate the back support member 50 moving to a reclined position 82, the rebound action of the occupant removing their weight from the back support frame 50 will not provide enough force to rebound the back support frame 50 substantially past the non-flexed position 80 into a forward, hyper-extended position (not illustrated). Further, the back frame support cross-member 58 will contact the lower surface of the seat cushion 90 if the back frame is flexed substantially forward, thereby also preventing hyper-extension.
As illustrated in
Alternative embodiments for the spring units 62 include a plurality of spring members 64 stacked and aligned on each other, thereby increasing the rigidity of each spring units 62. Alternative spring members include planar spring members having a plurality of widths, thicknesses, or lengths depending on the design of the stackable chair and the weights of the occupants predicted to be supported by the back support frame 50 during repetitive reclining movements. Each spring member 64 is composed of substantially stiff material, such as one example including layered fiberglass, which is capable of being repetitively flexed along a length dimension without failure. The chemical composition of each spring member 64 can be modified for production of a spring member having greater or lesser flexibility.
While the present invention has been illustrated by description of some embodiments, and while the illustrative embodiments have been described in detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant's general inventive concept.
