US3131924A - Spring base for upholstered seat backs - Google Patents

Description

y 5, 1954 R. o. lsAAcs 3,131,924

SPRING BASE FOR UPHOLSTERED SEAT BACKS Filed Aug. 9, 1962 3b 28 f0 1 3 21 .7416 3a .24 y 4042 INVENTOR. fimwa L220.

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United States Patent O 3,131,924 SPRING BASE FOR UPI-IGLSTERED SEAT BACKS Robert 0. Isaaes, Joplin, Mo., assignor to Flex-O-Lators, Inc., Carthage, Mo., a corporation of Missouri Fiied Aug. 9, 1952, Ser. No. 215,844 7 Claims. (Cl. 267-107) This invention relates to new and useful improvements in upholstered, spring-based furniture, and has particular reference to a spring base particularly adapted for use in seat backs.

Among the main objects of the present invention is the provision of a spring base which is quite firm and will hold its form through long periods of hard usage, so as to preserve the padding and upholstery layers applied thereover in a neat, tailored appearance, but which nevertheless possesses the softness and yieldability quite adequate for comfort. The upper edge of the base is a soft edge for comfort, that is, it will yield rearwardly, but is supported in a novel manner with suflicient firmness to prevent sagging, or the assumption of an uneven or undulating line even after long periods of usage. Provision is also made for preventing lateral movement of the upper edge of the base. The base structure involves spring strips more or less rigidly fixed at their upper and lower ends, and having their intermediate portions bowed forwardly. This type of structure, which is in common usage in seat backs, has a common fault in that as said strips are deflected rearwardly by the pressure of a persons back to a rearwardly bowed position, they tend to snap, or change their direction of bowing very suddenly as they pass between their upper and lower supports. This snap-action causes a disconcerting, uncomfortable sensation. The present structure has novel means for overcoming this fault.

Another object is the provision of a spring base of the character described which is adapted to be supplied to furniture manufacturers as a completely integrated unit not requiring any additional assembly, and which may be mounted in a furniture frame with the least possible time and labor, and with no tools or implements other than hammer and nails. Before mounting in the furniture frame, the base may be collapsed into an extremely compact form for greater convenience and economy of storage, handling and shipping.

A further object is the provision of a spring base of the character described having a novel means for providing additional support for the lower portion of a persons back, thereby encouraging better seating posture and reducing fatigue.

Other objects are simplicity and economy of construction, efliciency and dependability of operation, and adaptability for use in furniture of a wide variety of styles and types.

With these objects in view, as well as other objects which will appear in the course of the specification, reference will be had to the accompanying drawings, wherein:

FIG. 1 is a front elevational view of the back portion of a furniture seating frame, showing a spring base embodying the present invention mounted therein, with the padding and upholstery layers omitted,

FIG. 2 is a sectional view taken on line HII of FIG. 1, indicating the seat cushion in dotted lines, and

FIG. 3 is a view of the spring base only, separated from the furniture frame and collapsed for shipping or storage.

Like reference numerals apply to similar parts throughout the several views, and the numeral 2 applies generally to the back frame of a furniture piece such as an up holstered chair, couch, sofa or the like, a chair being shown for the purposes of illustration. The remainder of the frame, such as the seat, legs and arms, is not pertinent 3,131,924 Patented May 5, 1964 to the present invention and is not shown. Said frame comprises a pair of side uprights 4 connected at their upper rear portions by ahorizontal cross bar 6, at their lower rear portions by a horizontal cross bar 8, and at their lower forward portions by a horizontal cross bar 10. Said uprights and cross bars are formed of wood or other suitable material, and are rigidly connected to form a rigid, unitary structure. In the particular embodiment illustrated, the upper portions of uprights 4 are provided with outward offsets forming wings 12 which in the finished chair will overlie the upper surfaces of the chair arms.

The spring base forming the subject matter of the present invention is indicated generally by the numeral 14, and includes a plurality of compound spring units (five illustrated) each indicated generally by the numeral 16. Each of said units comprises a vertically extending spring steel strip 18 arranged to flex forwardly and rearwardly and fixed at its lower end to frame cross bar 10 as by a nail 20, and a generally S-shaped auxiliary spring strip 22 (see FIG. 2) alfixed at one end to end of strip 18, adjacent the upper end thereof, by a pair of rivets 24. From its point of attachment to strip 18, strip 22 is curved rearwardly and downwardly, then upwardly, and is affixed at its opposite end to frame cross bar 6, as by a nail 26. The upper end portions of strips 18 are thus normally supported well forwardly of cross bar 6, so as to be rearwardly yieldable, and strips 18 are flexed in a forwardly bowed position as shown in FIG. 2. The spring units 16 are disposed generally in regularly spaced relation across the Width of the chair, as indicated in FIG. 1. A greater or smaller number of units could be used, as necessary or desired. 7

The upper ends of strips 18 are joined by a series of short connectors 28, 3t), 32 and 34, each formed of a length of spring steel strip. Each of said connectors extends between and overlaps the upper ends of a successive pair of strips 18, and the overlapping contiguous ends of each successive pair of connectors are pivoted to the associated strip 18 by a rivet 36. The sidemost connectors 28 and 34 are extended outwardly from the associated strips 18, and each has a hole 38 formed in the extended portion thereof. One end of a tension spring 40 'is secured in each of holes 38. Said springs extend laterally outwardly and rearwardly, and each is secured at its outer end to a nail 42 driven into the upper end of the associated frame upright 4. The intermediate portions of spring strips 18 are joined by a continuous spring steel connector strip 44 which extends horizontally, being pivoted to each of strips 18 at its point of intersection therewith by a rivet 46. Intermediate connector 44 and the lower ends of strips 18, each strip 18 has an S-bend 48 formed therein and lying generally in the same vertical plane as strips 13 and 2-2 of the spring unit. Said S-bend provides a forward to rearward offset, so that the portion of strip 18 below the bend is offset rearwardly from the portion above the bend. The purpose of these S-bends will bediscussed presently. It will be understood that frame 2 and spring base 14 will in actual use be covered by upholstery material such as spring insulation, padding and decorative fabric, but that these layers have been omitted from the drawing for purposes of clarity.

In use, it will be seen that as a person leans rearwardly against the back, the strips 18 will be flexed from the forwardly bowed position shown in FIG. 2 to a rearwardly bowed position, in addition to a general rearward movement provided by compression of the s-shaped auxiliary springs 22. In moving from a forwardly to a rearwardly ward a vrearwardly bowed position. If the distance between the upper and lower ends of strips 18 were fixed, as if both ends were afiixed to frame 2, then the strips would be forced into an S-bend as they passed between the Supports, and would snap to their rearwardly bowed positions. This snap action, previously discussed, is highly objectionable. In the ,present'structure, the connection between the upper ends of strips 18 formed by connector links 28, 30, 32 and 34 is free to move upwardly as strips 18 lengthen, so that the strips may move freely and smoothly from forwardly to rearwardly bowed position with no snap action. S-shaped auxiliary springs 22 of course do not interfere appreciably with vertical movement of the upper ends of strips 18.

' However, if connections 28, 30, 32 and 34 were a continuous member rather than pivoted links as shown, snap action could occur, since a persons weight is seldom if ever applied uniformly across the entire width of a chair back, but is concentrated more heavily at one part of the chair width. Hence strips 18 must lengthen unequally as they are flexed, and those strips which must lengthen to a greater extent, being restricted by the top connector, which is in turn restricted by strips 18 which are not lengthened to the same degree, would still have a snap action. In the present structure, the snap action due to unequal lengthening of strips 18 is prevented by'relative pivoting of connector links 28, 30, 32 and 34. That is, if one strip 18 tends to lengthen more than those adjacentto it, upper end is freed .to move upwardly to a'gre-ater extent by pivotal movement'of. the adjacent links, as indicated in dotted lines at 30' and 32"in FIG. 1, although it is exaggerated in the drawing for clarity. Relative pivoting of the links occurs to some degree every time the seat back is flexed, and while such pivoting does draw the upper ends of strips 18 somewhat closer together, the movement is so slight as to be almost imperceptible, and in any event is rendered quite easy by the free lateral movement of 18 which results from springs 40 and. springs 22.

Therelative pivoting of connector links 28, 30, 32 and 34' could result in permanent angular relation thereof due to gradual deformation of strips 1 8 over long periods of usage, and since said connector links'form the padding support for the upper edge of the cushion, such permanent anglingpof the connector would result in a sagging, undulating, uneven, or otherwise unsightly edge, were it not for springs 40. These springs maintain the-chain formed by links 28, 30, 32 and 34 under constant tension and hence normally straight. Thus a neat, tailored edge is retained even after long, hard usage. Springs 40 also function to prevent to a great degree any general lateral movement of side sway of the upper portion of the springbase.

The S-bends 48 of strips 18 are disposed preferably at or above the seating level of the chair, as indicated by the seat cushion 50 shown in dotted lines in FIG. 2. It will be understood that said cushion is compressible, and is itself supported on a spring base, not shown. Hence when a person sits in the .chair, the S-bend 48 forms a rearward offset, overlaid by padding of course, which engages the persons back somewhat above the bottom of his hips. This provides a posture chair in that the persons hips may move somewhat rearwardly beneath the S-bend, and additional support is provided for the lower back. This reduces fatigue, and is conducive to better posture. The actual elevation of bends 48 is of course subject to variation as deemed advisable. An S-bend has been found to be preferable to a .contoured strip 18 wherein the strip is curved to an actual theoretical curve of the humanspine, or to any type of angular offset, since the S-bend maintains the entire length of the strip in a virtually pure bending stress as it is flexed in use, while a contoured or angularlyoffset strip creates zones of stress concentration leading to early failure. On standard furniture machines the back shown withstood up 4 to five and six more flexings with the S-bend,.before failure, as the same back contoured or angularly offset springs 18.

S bends 48 are also useful in connection with the lengthening action of 18 as described in connection with links 28, 30, 32 and 34. Firstly, the S-bends do permit some degree of relative vertical movement between the portions of the strip above and below the bend. This permits a shortening of the strips 18 to offset partially the total lengthening required, so that less movement of 28, 30, 32 and 34 is required. Secondly, S-bends 48 permit shortening of the strips 18 between their lower ends and continuous connector strip 44. Said connector strip is desirable, to maintain proper spacing of strips 18 and to provide better general stability of the structure, but nevertheless does inhibit relative vertical movement of the strips 18 and could permit snap action of the lower portions of strips 18, if it were not for bends 48. I V

As shown in 'FIG. 3, the spring base 14, when it is separated from the frame, may be collapsed or folded into a very compact form with spring units lying in contacting relation in parallel planes, due to the pivotal action supplied by rivets 36 and 46. This greatly reduces the bulk of the spring base, and constitutes a great advantage when storing, shipping or handling said bases, in that a much greater number of them may be packed into a small space. Assembled spring decks or bases of the general type shown are notoriously inconvenient to ship and store, due to their extremely large bulk as compared to their weight. This expense has made it necessary in many instances to sell and ship spring bases in a knockeddown or disassembled condition, so that assembly and mounting thereof was a tedious and expensive procedure for the furniture manufacturer utilizing them. The present base may feasibly and economically be furnished in completely assembled form, and may be mounted quickly and easily with only a hammer and nails.

While I have shown and described a specific embodiment of my invention, it be readily apparent that many minor changes of structure and operation could be made without departing from the spirit of the invention as defined by the scope of the appended claims.

What I claim as new and desire to protect by Letters Patent is:

1. In combination: (a) -a furniture seat including a back frame having rigidly associated top and bottom horizontal cross bars, and (b) a spring base mounted in said back frame and comprising:

(1) a plurality of upright spring strips spaced regularly across said frame and each affixed at its lower end to said bottom cross bar and extending upwardly therefirom, the intermediate portion of each strip being normally bowed forwardly and the upper end thereof being spaced apart forwardly from said top cross bar,

(2) a compressible auxiliary spring element secured at its forward end to each of said upright stripsradjacent the upper end thereof, and secured at its rearwardend to said top cross bar, and

(3) a horizontal cross strip extending across said spring base at the upper ends of said upright strips and comprising a series of links of flat spring material, each successive pair of said links being connected pivotally together, and to the upper end of one of said upright strips, on an axis normal to the general plane established by said upright p 2. The combination as recited in claim 1 with the addition of:

(a) resilient means biasing said links toward a straight,

aligned relation.

3. The combination as recited in claim 1 with the addition of:

(a) resilient means tensioning said cross strip longitudinally, whereby the thereof are biased yieldably toward a straight, aligned relation.

4. The combination as recited in claim 1 with the addition of:

(a) a pair of tension springs secured respeotively to opposite ends of said cross-strip, said springs extending longitudinally outwardly from the ends of said cross strip and being secured at their outer ends to said frame, whereby said cross strip is tensione-d.

5. The combination as recited in elm 1 wherein each of said upright strips is formed in an S-shape at or immediately above the seating level of said seat, so that the portion of the strip below said S-shape is ofiset rearwardly item the portion thereof above said S-shape.

6. The combination as recited in claim 1 wherein each of said upright strips is formed in an S-shape at or immediately above the seat ng level of said seat, so that the pontion of the strip below said S-shape is offset rearwardly firorn the portion thereof above said $-shape, and with the addition of:

(a) a continuous horizontal cross strip extending across said spring base and being secured to each of said upright strips at a point intermediate the S-shape thereof and said first-named top cross strip.

7. The combination as recited in claim 6 wherein said continuous cross ship is pivoted to each of said upright strips on an axis parallel to the pivotal connection of said linked across srtm'p thereto, whereby when said spring base is separated Tom said firame, the former may be folded so that said upright strips are disposed in parallel, abutting relation.

Ball Mar. 17, 1936 Flint Apr. 30, 1957

Claims (1)

1. IN COMBINATION: (A) A FURNITURE SEAT INCLUDING A BACK FRAME HAVING RIDGIDLY ASSOCIATED TO AND BOTTOMM HORIZONTAL CROSS BAR, AND (B) A SPRING BASE MOUNTED IN SAID BACK FRAME AND COMPRISING: (1) A PLURALITY OF UPRIGHT SPRING STRIPS SPACED REGULARLY ACROSS SAID FRAME AND EACH AFFIXED AT ITS LOWER END TO SAID BOTTOM CROSS BAR AND EXTENDING UPWARDLY THEREFROM, THE INTERMEDIATE PORTION OF EACH STRIP BEING NORMALLY BOWED FORWARDLY AND THE UPPER END THEREOF BEING SPACED APART FORWARDLY FROM SAID TOP CROSS BAR, (2) A COMPRESSIBLE AUXILIARY SPRING ELEMENT SECURED AT ITS FORWARD END TO EACH OF SAID UPRIGHT STRIPS ADJACENT THE UPPER END THEREOF, AND SECURED AT ITS REARWARD END TO SAID TOP CROSS BAR, AND (3) A HORIZONTAL CROSS STRIP EXTENDING ACROSS SAID SPRING BASE AT THE UPPER ENDS OF SAID UPRIGHT STRIPS AND COMPRISING A SERIES OF LINKS OF FLAT SPRING MATERIAL, EACH SUCCESSIVE PAIR OF SAID LINKS BEING CONNECTED PIVOTALLY TOGETHER, AND TO THE UPPER END OF ONE OF SAID UPRIGHT STRIPS, ON AN AXIS NORMAL TO THE GENERAL PLANE ESTABLISHED BY SAID UPRIGHT STRIPS.

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