US2935124A

US2935124A - Spring unit for cushion spring assemblies

Info

Publication number: US2935124A
Application number: US744955A
Authority: US
Inventors: John G Platt
Original assignee: Flex O Lators Inc
Current assignee: Flex O Lators Inc
Priority date: 1958-06-27
Filing date: 1958-06-27
Publication date: 1960-05-03
Anticipated expiration: 1977-05-03

Description

May 3, 1960 J. G. PLATT SPRING UNIT FDR CUSHION SPRING ASSEMBLIES Filed June 27, 1958 John 6: Fla/f Aria/wax 2,935,124 Fate-mated May"3,- 1960 lie SPRING UNIT FQR CUSHION SPG V ASSEMBLIES John G. Piatt, Carthage, Mo., assignor to Fiex fi-Lators, Inc., Carthage, Mo., a corporation of Missouri Application June 27, 1958, Serial No. 744,955

Claims. (Cl. 155-179) This invention relates to new and useful improvements in cushion spring assemblies for furniture, automotive seating and the like, and has particular reference to spring assemblies of the type comprising a series of substantially planar spring units disposed in spaced apart vertical planes and each connected to a furniture frame only at its opposite ends.

An important advantage of the above type of spring units has been that since they aresubstantially planar, they may be packed flat in a very compact package for handling, storage and shipping, thus overcoming the usual disadvantage of'other spring units which are extremely bulky in proportion to their weight and hence difiicult to store and expensive to ship. They are also quite economical. in cost, simple to install, and do not require specially fabricated or complicated furniture frames to accommodate their use.

On the other hand, spring units of the type described have been subject to certain disadvantages, particularly with regard to obtaining an assembly having the desired characteristics of yieldability over the entire area of a spring deck produced from such units. Specifically, spring assemblies produced from these units have exhibited a pronounced tendency to sag excessively in the portion thereof midway between the secured ends of the units, since the units are secured only at their opposite ends and must of necessity have a considerable span. Attempts to stiffen the mid-portion of the load-supporting deck to prevent sagging as described, have generally resulted in a structure which is objectionably stiff or hard when a person first applies his weight thereto. An important object of the present invention is, therefore, the provision of a spring unit of the character described having novel means for stiffening the mid-portion thereof to prevent excessive sagging as above discussed, and which nevertheless will initially be sufficiently yieldable to preserve the feeling of depth and luxury so essential in modern seating. The central stiffening means, for this reason, are comparatively inactive during the initial compression of the units, but become increasingly effective as a greater load is applied and the deflection becomes correspondingly greater.

1 Another disadvantage of spring units of this type has been that since the load-supporting deck of the assembly must of necessity be disposed well above the level of the furniture frame to which the ends of the units are secured, there must be vertically extending spring portions between the spring ends and the portions thereof forming the deck. These vertically extending portions are of course resiliently yieldable, and hence can move horizontally, with the result that the deck can sway from side to side in any direction. This lack of horizontal stability, even though slight, can be disconcerting to the -user, and definitely detracts from the comfort of the cushion. Another object of the present invention is, therefore, the provision of means for horizontally stabilizing ;the;unit s to minimize such swaying.

ability for use in many types and varities of furniture. I

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 drawing, wherein:

Fig. 1 is a top plan view of a cushion spring assembly comprising spring units embodying the present invention,

Fig. 2 is a sectional view taken on line 11-11 of Fig. l, with parts broken away, and

Fig. 3 is an enlarged sectional view taken on line III-III of Fig. 2.

Like reference numerals apply to similar parts throughout the several views, and the numeral 2 applies generally to a furniture frame which by way of example will hereinafter be referred to as a seat frame, although it will be readily apparent that the concepts involved are equally adaptable to back frames, couches, automotive seating, .and in nearly any application involving spring cushions. Said frame as shown is formedvof wood and is of rectangular form, comprising a front rail 4, back rail 6, and parallel, spaced apart side rails 8, all rigidly joined together in a unitary structure. A plurality of spring units each embodying the present invention and each designated generally by the numeral 10, are mounted insaid frame. Each of said units is approximately planar, and said units are disposed in vertical planes spaced regularly across the width of frame 2. Each of said spring units comprises a main spring 12, a secondary or auxiliary spring 14, and a stabilizing spring 16, all formed of fiat spring steel stock or other suitable material.

Main spring 12 includes a substantially straight central portion 17 which is disposed above and approximately parallel to the plane of the frame, and which in conjunction with the like portions of the other units forms the load-supporting platform ordeck of the assembly. At the forward end of section 17, the main spring is bent to form, successively, a forwardly and up wardly inclined bight or loop 18, a rearwardly and downwardly inclined leg 20, bend 22, a forwardly extending leg 24, and a downwardly extending terminal leg 26 adapted to be secured to front rail 4 of the frame. At the rearward end of central section 17, the main spring is bent to form successively, a bend 28, a forwardly and downwardly inclined leg 30, bend 32, a downwardly and rearwardly inclined leg 34, and a downwardly extending terminal leg 36 adapted to be secured to back rail 6 of the frame.

Secondary spring 14 is shaped somewhat similarly to the main spring, having a horizontal central portion 38 disposed beneath and in engagement with central port-ion 17 of the main spring but of shorter span than portion 17, and being secured thereto intermediate its ends by a rivet 40. At the forward end of portion 38, the secondary spring is bent to form, successively, a bend 42, a downwardly and rearwardly inclined leg 44 contacting leg 20 of'the main spring, a bend 46 engaging bend 22 of the main spring, a forwardly extending leg 48 lying beneath leg 24 of the main spring and affixed thereto by rivet 50, and .a downwardly extending terminal leg 52 adapted to be secured to frame rail 4. Spring legs 26 and 52' are both secured to rail 4 by a common setof fasteners such as nails 54. At the rearward end of portion 38, the secondary spring i bent to form, successively, a bend 56, a downwardly and forwardly inclined leg 58, bend 60, a downwardly and rearwardly inclined leg 62 which lies against leg 34 of the main spring and is secured thereto by rivet 64, and a downwardly extending terminal leg 66 adapted to be secured to frame rail 6. i t

Stabilizing spring 16 has one end portion 68 thereof Other objects are similicity and economy of construcsecured to the central portions 17 and 38 of the main and secondary springs by rivet 40, and extends forwardly from its point of attachment. It is then bent to form, successively, a bend 70, a downwardly and rearwardly inclined leg 72 which lies beneath and in contact with leg 62 of the secondary spring and is secured thereto by rivet 64, and a downwardly extending terminal leg 74 adapted to be secured to frame rail 6. The rearward terminal legs of all of the spring members are secured to rail 6 by a common set of fasteners such as nails 76.

All of spring units 10 are interconnected and stabilized against movement transverse to their planes by a plurality of flexible steel tie strips 78 extending transversely across the load-supporting deck of the assembly, each of said strips being secured to the central portion 17 of each main spring at its point of intersection therewith, as by a rivet. The illustration shows two such tie strips disposed respectively adjacent the forward and rearward edges of the deck, and secured by rivets 80, and a third tie strip disposed intermediate the front and rear edges of the deck and secured by rivets 40, although a larger or smaller number of strips could obviously be used if desired. It will be understood that the spring assembly as shown is in actual use covered by suitable layers of padding and upholstery.

The operation of the spring assembly is substantially as follows: At least two features contribute to a stiffening or reinforcing of the central portion of each spring unit 10 whereby to prevent excessive sagging thereof when loaded. Firstly, the fact that the rearwardly extending

legs

34, 62 and 72 of the main, secondary and stabilizing spring members are rigidly secured together by rivet 64, and forwardly extending

legs

24 and 48 of the main and secondary springs are secured together by rivet 549, provides that each unit has end portions which are effectively much stiffer than the central portion, since the end sections are of double or triple thickness and must flex as a unit. Thus the unit is rendered of more uniform strength from end to end in much the same manner as would be provided by a multi-leaf spring wherein the leaves are of graduated lengths, and the effective points of support for the central deck portions are moved'inwardly from rails 4' and 6. Secondly, secondary spring 14 and auxiliary spring 16 provide additional direct support under the central portion 17 of the main spring to brace the same against undue deflection. In this connection, two special provisions should be noted. First, it will be seen that forward bend 42 of the secondary spring, which is relatively rigid as compared to an extended length of the spring, is seated directly be tween central portion 17 and leg 20 of the main spring, while the portions of the secondary and stabilizing spring at the rearward end section of main spring section 17 not only do not seat on leg 3% of the main spring, but are spaced respectively at substantial distances forwardly from leg 30. This relationship provides that the forward edge of the cushion will be slightly stiffer, that is, will have a slightly greater resistance to initial downward deflection, than the rearward edge. This. defeats any tendency of the deck to tilt forwardly as a person applies his weight thereto, and on the contrary produces a very slight rearward tilting. This is conducive to comfort as it, tends to move the person toward the seat back (not shown) and hold him firmly in the seat. On the other hand, any tendency toward forward tilting creates a sensation of slipping out of the seat, and is distinctly uncomfortable. Secondly, the compound leg formed by leg 34 of the main spring and the portions of legs 62 and 72 of the secondary and stabilizing springs, which are secured to leg 34 by rivet 64, yields a relatively small distance as compared to central portion 17 of the main spring as a load is applied thereto, and there is therefore a substantial relative movement between section 17 and leg 34. Also, the portions of legs 62 and 72 extending forwardly from rivet 64 are initially unstressed, and it will be apparent that they will not supply appreciable support to section 17 until section 17 has been deflected sufliciently, relative to leg 34, to flex the forward portions of legs 62 and 72, relative to leg 34. Thus the section 17 is initially relatively soft and yieldable, but becomes progressively, firmer as .the secondary and stabilizing springs are brought into play as described. Excessive yieldability or sagging'of the assembly is therefore prevented, while at the same time preserving the initial softness or yieldability which is necessary to a feeling of luxurious comfort or depth.

Stabilizing spring 16 also has the valuable function of preventing undue forward and rearward movement or swaying of the deck portions 17 of the units. Were it not for the stabilizing spring, the double bend at each end of section 17, and at' each end of the secondary spring would permit such movement, That is, for example, a forward movement of a person sitting on the cushion would cause an opening or straightening action on bends 28 and 32 of the main spring and bends 56 and 60 of the secondary spring, and a closing action on

bends

18, 22, 42 and 46 of the main and secondary springs, and section 17 would move forwardly. Such a movement creates a feeling of instability and discomfort,

. and is also accompanied by a tilting or rocking movement which causes further discomfort. The stabilizing spring 16, however, has only a single bend 70 therein between main spring section 17 and its point of attachment to rail 6. Therefore a mere opening action of bend 7 0, as distinguished from the double bends of the main and secondary springs, will not permit any appreciable forward movement of the upper end of the stabilizing spring. Forward movement at this point would require that bend 70 to be unrolled by opposite longitudinal forces in the spring at opposite sides of the bend, and the spring is relatively highly resistant to this type of deformation.

Bend 70 could of course be eliminated, and spring 16 extended substantially straight to a point of attachment to main spring section 17. This would provide the forward and rearward stabilization as discussed, but would be too' severe in that it would prevent any degree whatsoever of forward movement. Such absolute stabilization is in itself undesirable, as complete immovability of the deck in any direction creates an anchored or tethere'd" feel which is not conducive to comfort. The single bend 70 has been found to produce adequate stability and still to be sufficiently yieldable for comfort. Spring 16 also stabilizes against rearward movement, since rearward movement places leg 72 thereof in compression, and since said leg is supported along most of its length by its proximity and attachment to legs 34 and 62 of the main and secondary springs.

While I have shown and described a specific embodiment of my invention, it will be 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.

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

l. A spring unit for use in a cushion spring assembly comprising a plurality of such spring units disposed in substantially parallel, horizontally spaced apart vertical planes ina suitable frame, said spring unit comprising a main spring formed of a single length'of resilient ma- 'terial having a generally straight central portion disposed generally horizontally above said frame and an inwardly converging V-formation at each end of said central portion, said V-forrnations having upper and lower legs and being adapted to be secured at their lower ends to said frame, and a secondary spring formed similarly to said main spring, the central portion thereof being of shorter span than but disposed directly beneathand aifixed to the central portion of said main spring, and the V-formations at the ends thereof also being adapted to be afiixed to said frame, the upper leg of the V-formation, at one end of said secondary spring being seated directly on the corresponding leg of said main spring, and the lower leg of the V-formation at the opposite end of said secondary spring is substantially longer than the corresponding leg of said main spring, whereby the upper legs of the V- formations at this end are spaced substantially apart.

2. A spring unit as recited in claim 1 wherein the lower legs of the .V-formations at both ends of theunit are rigidly secured together to form legs of greater thickness and stiifness.

3. A spring unit for use in a cushion spring assembly comprising a plurality of such spring units disposed in substantially parallel, horizontally spaced apart vertical planes in a suitable frame, said spring unit comprising a main spring formed of a single length of resilient material having a generally straight central portion disposed generally horizontally above said frame and an inwardly converging V-formation at each end of said central portion, said V-formations having upper and lower legs and being adapted to be secured at their lower ends to said frame, and a secondary spring formed similarly to said main spring, the central portion thereof being of shorter span than but disposed directly beneath and aflixed to the central portion of said main spring, and the V-formations at the ends thereof also being adapted to be aflixed to said frame, and a stabilizing spring comprising a length of resilient material having upper and lower legs connected by a single reverse bend, said upper leg being secured to the central portion of said main spring intermediate the ends thereof, and said lower leg being adapted to be secured at its lower end to said frame.

4. A spring unit as recited in claim 2 with the addition of a stabilizing spring comprising a length of resilient material having its upper end portion secured to the central portion of said main spring and having a lower leg extending toward the end of said unit at which the lower legs of the V-formation is of the main and secondary springs are of unequal lengths, and adapted to be attached at its lower end to said frame, the lower leg of said stabilizing spring being of greater length than the corresponding lower leg of the V-formation of the secondary spring, and attached rigidly to the lower legs of the corresponding V-formations of the main and secondary springs.

5. A spring unit as recited in claim 4 wherein said stabilizing spring comprises upper and lower legs connected by a single reverse bend, the upper leg thereof being aifixed to the central pontion of said main spring.

245,447 Chittenden Aug. 9, 1881 Mengel Aug. 1, 18s;