Beds – Mattress – Having innerspring-type core
Reexamination Certificate
2000-06-02
2001-07-24
Trettel, Michael F. (Department: 3628)
Beds
Mattress
Having innerspring-type core
C005S739000, C005S740000
Reexamination Certificate
active
06263533
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains generally to flexible support structures such as seating and bedding and, more particularly, to internal flexible structures for use in mattresses and furniture.
BACKGROUND OF THE INVENTION
Innerspring assemblies for mattresses or seating structures such as sofas are generally composed of a plurality of spring coils tied together in a matrix or array. In a mattress innerspring, border wires usually encircle both the upper and lower perimeters of support surfaces formed by the ends of the vertically oriented coils. The border wires are connected to convolutions of the perimetrical springs by hog rings. The border wires are attached to top and bottom convolutions of the perimeter coils. Alternatively, the coils may have offset sections located near the ends which extend radially beyond the terminal convolutions, and wherein the terminal convolutions extend axially beyond the offset sections, as described for example in Sealy U.S. Pat. No. 5,713,088. It is a common practice to overlap the terminal convolutions of adjacent spring coils in a row, and then wind even smaller diameter helical spring coils, referred to as cross-helicals, across the rows to encircle the overlapped terminal convolution portions. Such an innerspring construction is described for example in Sealy U.S. Pat. No. 4,726,572. Other types of innersprings may have spring and support elements made or plastic or composite materials.
With respect to the perimeter of the innerspring assemblies of mattresses, there are some general considerations of construction and manufacture. In the normal use of a mattress, the edges of the innerspring are subjected to greater compression forces than the interior of the innerspring, largely due to the common practice of sitting on the edge of the bed. The added stresses and strains on the edges of the innerspring are evident in a general rounding of the mattress at the perimeter, creating a condition known as “roll-off”. This is especially true of the edges and corners of a mattress which are the weakest structural points of the mattress, particularly in lower end mattress designs in which the innerspring assemblies rely entirely on the weight bearing ability of the coils for the mattress to maintain its shape. The innerspring can further give the impression of a degree of softness it does not have, since a person sitting on the edge provides a much more concentrated load on the underlying springs than a prone body upon a central portion of the innerspring.
Different types of reinforcements have been used in connection with innerspring assemblies to overcome these weaknesses. For example, Sealy U.S. Pat. No. 5,787,532 describes various foam structures interlockingly engaged with mattress innersprings to improve the shape and support characteristics. Some of the foam shapes described, though highly functional, are rather complex and therefore somewhat difficult to manufacture and assemble. Extrusion of foam pieces of different cross-sectional configurations has been proven to be efficient, so long as the shape is not overly complex. Also, dimensional tolerance is sometimes difficult to achieve given the somewhat unpredictable expansion behavior of different types of foam as it exits the extrusion die. Therefore, foam pieces of relatively simple cross-sectional configuration are preferable for consistency. Also, smaller and more compact foam pieces are easier to engage with innerspring assemblies. Large or long structures have a tendency to disengage before the padding and upholstery is attached over the foam to secure it in place. The assembly of mattresses is largely a manual process. In particular, the installation of padding and upholstery to the top and bottom surfaces of the innerspring and about the borderwire is very difficult. Much dimensional variation can occur in the process, due to deflection of the springs and compression of the padding material, resulting in uneven seam lines. Adding structural elements to the innerspring.
SUMMARY OF THE PRESENT INVENTION
In view of the difficulties and drawbacks encountered with previous innerspring; reinforcement structures, there is a need for various types of modular innerspring reinforcements which provide rigidity and shape-retention of the innerspring. There is also a need for relatively simple mattress reinforcement structures which are easy to manufacture to consistent tolerances, and easy to install in a manual assembly process.
The present invention provides four different types of extruded foam innerspring reinforcement structures of relatively simple geometry, which are easy to manufacture and install or engage with an innerspring. The four types of innerspring reinforcement structures include: 1) a corner coil reinforcement member; 2) a side wall reinforcement member having a planar wall section, 3) a single piece side wall reinforcement, and 4) a tapered edge reinforcement member.
In one aspect of the invention, there is provided an extruded foam corner coil reinforcement configured to fit axially about an outer diameter of each of the corner coils of an innerspring unit, and between upper and lower border wires. The corner coil reinforcement structure substantially strengthens the innerspring at the corners and improves the dimensional stability and appearance of the overlying padding and upholstery.
In another aspect of the invention, there is provided an extruded foam reinforcement structure configured for engagement with coils of the innerspring to substantially strengthen the sides of the innerspring. One or more vertically disposed vertical members are engaged between the turns of adjacent coils at the perimeter of the innerspring. A planar wall portion is attached to the vertical members to closely abut the perimetric coils and provide a smooth substantially rigid side wall to the innerspring over which padding and upholstery is attached.
And in another aspect of the invention, there is provided a tapered anti-roll-off extruded foam structure adapted to fit at an edge of a supporting surface of an innerspring. The structure provides a surface edge which is tapered inward from the edge toward the center of the innerspring support surface, and a registration lip which fits over a borderwire or top edge of the perimetric coils of the innerspring, to accurately position the edge structure. The edge structure counters the roll-off effect of innersprings.
The invention further includes innerspring assemblies in combination with all or combinations of some of the four disclosed reinforcement structures.
These and other novel aspects of the invention are herein described in particularized detail with reference to the accompanying Figures. While shown in certain preferred and alternate embodiments, it will be appreciated that the basic concepts and forms of the invention could be implemented in other equivalent ways which are nonetheless within the scope of the invention as defined by the accompanying claims and equivalents thereof.
REFERENCES:
patent: 2826769 (1958-03-01), Drews
patent: 3100305 (1963-08-01), Kaye
patent: 3618146 (1971-11-01), Ferdinand
patent: 4286344 (1981-09-01), Ikeda
patent: 5133116 (1992-07-01), Wagner et al.
patent: 5210890 (1993-05-01), Hagglund
patent: 5239715 (1993-08-01), Wagner
patent: 5787532 (1998-08-01), Langer et al.
Dimitry Said
Freeman William
Arter & Hadden LLP
Sealy Technology LLC
Trettel Michael F.
LandOfFree
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