Chairs and seats – Movable bottom – Tiltable
Reexamination Certificate
2000-10-20
2001-11-20
Nelson, Jr., Milton (Department: 3636)
Chairs and seats
Movable bottom
Tiltable
C297S300200
Reexamination Certificate
active
06318800
ABSTRACT:
This application is related to the following co-assigned patents and applications, which are filed on even date herewith. The disclosure of each of these patents and applications is incorporated herein by reference in its entirety:
TITLE
PATENT APPLN. NO.
FILING DATE
Chair Including
5,975,634
11/02/99
Novel Back Construction
Chair With Novel Seat Construction
5,871,258
02/16/99
Chair with Novel Pivot Mounts and
5,909,923
06/08/99
Method of Assembly
Synchrotilt Chair with
5,979,984
11/09/99
Forwardly Movable Seat
Seating Unit with Reclineable Back and
09/692,816
(filed on even date herewith)
Forwardly Movable Seat
Seating Unit with Novel
09/692,810
(filed on even date herewith)
Seat Construction
Seating Unit Including Novel
09/694,041
(filed on even date herewith)
Back Construction
BACKGROUND OF THE INVENTION
The present invention concerns seating units having a reclineable back, and more particularly concerns seating units having a reclineable back and a forwardly movable/tiltable seat that move with a synchronous movement as the back is reclined, and that are pivotally interconnected in a novel manner.
Reclineable chairs have gained wide and enthusiastic support in the chair industry. Reclineable chairs often include a back frame pivoted by back pivots to opposite sides of a base or control housing to define a back-tilt axis. A problem is that the back pivots do not always align perfectly with the back-tilt axis. This misalignment can be a result from the back pivots being skewed at an angle to the back-tilt axis, or from the back pivots being parallel to the back-tilt axis but non-aligned with it, or from the back pivots changing orientation as a person sits in the chair or reclines in the chair. A net result is that, during recline of the back, at least one chair component must flex and mechanically give to prevent binding. Typically, either the control housing or back frame structure deforms, and/or the bearing is sloppy enough to compensate for the misalignment. If the deformation is large enough or if the chair components are not designed for such flexing, one of the chair components may break, fail, or fracture over time due to cyclical fatigue failure. Another problem is that bearings of the back pivots will rapidly wear from the high forces generated by the misalignment. This results in looseness in the back, which can be objectionable in some situations.
Another problem with known back pivots for chairs is that they can be cumbersome to assemble and/or manually intensive to assemble, as well as expensive, since holes must be aligned to receive pivot pins/axles, and the pivot pins/axles must be adequately but not overly tightened and secured. Specifically, during securement, the pivot pins/axles cannot be overtorqued or the assembly will bind, and also cannot be undertorqued or the assembly will be unacceptably loose and prone to come apart.
Similar problems can occur in synchrotilt chairs where a seat has spaced-apart seat pivots that do not accurately align with a seat-tilt axis. It is noted that seat pivots must also support a large portion of the weight of a seated user, thus adding to his/her stress level.
Along with the above requirements, any back pivots and seat pivots must be integrated into the chair construction to provide an acceptable appearance, since they are often located in a highly visible area of a chair.
Accordingly, a chair construction solving the aforementioned problems is desired.
SUMMARY OF INVENTION
In one aspect of the present invention, a method of assembling a seating unit includes steps of providing a seating unit component with laterally-extending oppositely-facing protrusions, and providing a back frame with end sections having recesses therein. The method further includes flexing the end sections of the back frame and simultaneously positioning the recesses of the end sections on the protrusions, and also releasing the back frame so that the back frame resiliently returns to an original shape which holds the back frame in place and pivotally connects the back frame to the seating unit component.
In another aspect of the present invention, a seating unit assembly includes a base assembly having opposing side arms, a back frame with opposing end sections pivoted to the side arms at back pivots for rotation about a back-tilt axis, and a seat pivoted to the end sections at seat pivots for rotation about a seat-tilt axis. The back pivots includes a pair of inwardly-facing studs on the side arms, a pair of outwardly-facing frustoconically-shaped pockets formed in the opposing end sections for receiving the studs, a pair of elastomeric bushings fit mateably into the frustoconically-shaped pockets, and lubricious bearing elements positioned in the bushings that rotatably support the studs. The elastomeric bushings have an outer frustoconically-shaped surface for mateably engaging the frustoconically-shaped pockets from an assembly direction defined by a concavity of the frustoconically-shaped pockets. The elastomeric bushings are resiliently deformable so that, when the studs are misaligned with the back-tilt axis, the elastomeric bushings flex and deform to reduce binding and stress in the base assembly and the back frame upon recline of the back frame.
In another aspect of the present invention, a seating unit assembly includes a base assembly having opposing side arms, a back frame having opposing end sections pivoted to the side arms at back pivots for rotation about a back-tilt axis, and a seat pivoted to the end sections at seat pivots for rotation about a seat-tilt axis. The seat pivots include a pair of outwardly-facing studs on the seat, a pair of inwardly-facing frustoconically-shaped pockets formed in the opposing end sections for receiving the studs, a pair of elastomeric bushings fit mateably into the frustoconically-shaped pockets, and lubricious bearing elements positioned in the bushings that rotatably support the studs. The elastomeric bushings have an outer frustoconically-shaped surface for mateably engaging the frustoconically-shaped pockets from an assembly direction defined by a concavity of the frustoconically-shaped pockets. The elastomeric bushings are resiliently deformable so that, when the studs are misaligned with the seat-tilt axis, the elastomeric bushings flex to reduce binding and stress in the seat and the back frame upon recline of the back frame.
In yet another aspect, a seating unit assembly includes a base assembly having side arms, and a back frame having end sections pivoted to the side arms at back pivots for rotation about a back-tilt axis. The back frame is flexible enough to permit the end sections to be flexed apart during assembly. The end sections and the sidearms have adjacent faces, one of which has a frustoconically-shaped recess therein. A bearing arrangement is provided at each back pivot for pivotally connecting the side arms to the respective end sections. The bearing arrangement includes a stud that extends into a large end of the recess, and a bearing element rotatably engaging the stud. The bearing element is removable from the recess through the large end of the recess, but held therein in part by the proximity of the adjacent faces and by the strength of the back frame.
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Jr. Milton Nelson
Price Heneveld Cooper DeWitt & Litton
Steelcase Development Corporation
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