US3242512A - Bellows spring assembly - Google Patents

Description

March 29, 1966 R. H. BECKMAN BELLOWS SPRING ASSEMBLY 2 Sheets-Sheet 1 Filed March 3, 1964 INVENTOR WW1 14K 551/ 74 1 L/ BY March 29, 1966 R H. BECKMAN 3,242,512

BELLOWS SPRING ASSEMBLY Filed March 5, 1964 2 Sheets-Sheet 2 United States Patent 6 3,242,512 EELLOWS SPRING ASSEMBLY Ronald H. Beckman, 27 Bank St., New York, N.Y. Filed Mar. 3, 1964, Ser. No. 348,928 4 Claims. (Cl. -353) This invention relates to a resilient load supporting assembly, and more particularly to a vented, bellows spring cushioning assembly, especially for furniture, mattresses, cushions, automotive and general transportation seating.

One of the simplest and least expensive types of support construction is that employing a flexible sheet suspended on a peripheral frame. Although this basic construction is employed to some extent in modern furniture by stretching a canvas type material over a support, it is not widely used for high quality items since it does not provide optimum comfort. The sheet has limited flex under load. It does not have the capacity to depress comfortably more than a small amount under the weight of a person. Attempts have been made to improve the comfort characteristics by making the sheet of stretchable material so that it could shift and depress more readily. This does result in more give, but the sheet tends to wrap around the body portion of the resting person in an unpleasant manner. Also, the stretched material gives an insecure sensation as a person shifts his weight from one position to another. Therefore, peripherally suspended tension sheet supports are not widely employed in top quality furniture.

It is an object of this invention to provide a support construction enabling a tension sheet or pad to be employed to maximum advantage in furniture in a unique manner that produces a highly comfortable as well as a relatively inexpensive structure.

It is another object of this invention to provide a novel furniture construction employing the unique combination of a flexible stretchable support pad with special springs in a complementary manner effectuating excellent compressive support characteristics, but without the undesirable wrap-around tendency. The springs counteract the latter tendency of the stretch pad, while contributing beneficially to the former characteristics.

Still another object of this invention is to provide a furniture structure of a combination resilient, stretchable, polymeric, tension-suspended support pad with a plurality of polymeric, compressible, bellows springs so that the resulting combination is relatively inexpensive, readily assembled, and adaptable to a variety of different sizes and types of furniture.

Another object of this invention is to provide a furniture construction making a peripherally suspended tension element completely practical for usage in comfortable, high quality, modern style furniture manufacture.

These and other objects of this invention will become apparent from a study of the specification in conjunction with the drawings in which:

FIG. 1 is a perspective view of an exemplary article of furniture employing the novel combination;

FIG. 2 is an enlarged fragmentary perspective view of the underlying support construction in the article of FIG.

FIG. 3 is a plan view of one of the pad segments illustrated in FIG. 2 before assembly;

FIG. 4 is an elevational view of the pad segment in FIG. 3 shown stretched for attachment of bellows springs;

FIG. 5 is a fragmentary, enlarged, elevational, sectional view of one bellow-s spring being assembled with a stretched pad segment;

FIG. 6 is an elevational, enlarged, fragmentary, sectional view of the spring in FIG. 5 assembled in the pad 3,242,512 Patented Mar. 29, 1966 segment and intermeshing with a pair of adjacent bellows springs;

FIG. 7 is an enlarged, fragmentary, elevational view of a slightly modified form of the assembly in FIG. 6; and

FIG. 8 is a plan view of the assembly of one of the pad segments and a plurality of intermeshed bellows springs.

Referring now specifically to the drawings, in FIG. 1 is illustrated a typical article of furniture 10 employing this combination. This article includes a seat portion 12 and a back rest portion 14 supported on a plurality of legs 16.

The seat is peripherally outlined by a rectangular frame 18 connected securely to a like outline frame 20 for the back. The seat frame and back frame each support flexible web-type pad means 22 and 24 respectively. In the form of the invention shown, each of these pad means includes a plurality of pad segments 26 interconnected to form the web assembly. It will be understood that within the broader concepts of this invention, each of these may comprise a unitary pad rather than a plurality of interconnected segments.

Each of these segments is for-med of a polymeric, resilient, flexible, stretchable, material preferably of rubber or the equivalent. Each is of substantial thickness, for example around one-eighth to one-quarter inch, to support a load as well as being self-supporting. Each of the pad segments, when attached, is in slight tension. The attachment means on the periphery of each segment to secure the pad to each other and segments to the frame may be by any suitable means. For example, ring clips 28 may be employed. The number of clips employed depends upon the size of the article, the loads normally supported, and other design variations. These clips may interconnect with cooperating connector elements 30 on the frame portions.

The rubber pad segments are preferably molded individually to have optimum strength. They are shown in segmental form since molding is easier to achieve with these smaller units. The peripheral edge may be reinforced for additional strength and freedom from tearing. The thickness of the portions is made sufiicient to enable controlled give with stretching under load, yet not sufficient to allow excessive stretching for release of the springs attached in a unique way (to be described). The particular thickness can be varied to provide seating of different characteristics, for public or private use. The back pads may be of thinner material to more readily flex under the lighter load. Then too, mattresses formed of the novel combination will have different thickness than a chair, for example. In fact the thickness may vary from portion to portion, as from edge toedge in a mattress to effect controlled resiliency in all portions. This can be coupled with different wall thickness and/or degree of intermesh in the bellows springs. These dimensions can readily be determined by one skilled in the field for the particular use so that a long list of dimensions here would be superfluous.

Mounted on each of the segments and covering the entire surface area of the seat pad and the back rest pad is a plurality of bellows springs 34. Each of these springs is of a resilient polymeric material having a series of inner apices and outer apices forming hinge joints for axial compression of the spring.

Each of the bellows springs comprises a hollow undulated Wall formed of series of adjacent interconnected individual bellows of a resilient polymer. This polymer is preferably a low density polyethylene. It may alternatively be some other suitable polymer such as a polymer of ethylene and ethyl acrylate mixtures, or possibly a mixture of propylene and polyisobutylene polymers, or similar materials capable of being blow-molded from a central parison into a mold surrounding the parison. In a less preferred form of the invention where the spring is formed by the method of rotational casting the polymer may be a butadiene polymer.

The blow molding process is preferred because of the low cost of the molds, and the rapidity and accuracy of the process in reproducing springs of identical characteristics. Also springs of varying wall thicknesses can be formed with the same mold. This process is preferred also because of the desirable physical characteristics of the polymeric wall resulting from the polymer being forced. radially into the mold while blow molding, and because of a double action compression that results causing each individual spring to compress in two stages when compressed singly.

The wall thickness of the blown spring may be varied by variation of the wall thickness of the initial hollow parison to be blown, and/or by variation of the initial diameter of the parison with respect to the mold. Wall characteristics also vary with the polymeric material employed.

This blow molding process causes the wall of the outer peripheral extremities of the individual bellows to be thinner than the inner extremities, with the change in thickness being gradual over the legs. The greater the radial distance of the spring portion from the central parison being blow molded, the thinner the wall. These arcuate outer extremities have the least resistance to flexing, and therefore, comprise unique hinges which flex controllably over the entire arcuate surface. Each flexible outer hinge is integral with and joins the radially outwardly converging legs of each individual bellows, and is formed by the arcuate portion extending from one leg to the other.

Almost the entire deflection of each spring, when compressed singly, is a result of the flexure of the outer flexible juncture hinges, with only slight flexing occurring in the legs during spring compression under load. The flexing characteristics of the outer junctures depend upon the thickness of the junctures as well as the materials and the arcuate configuration thereof.

The thicker walled, inner junctures constitute the most rigid portion of the bellows construction. Therefore, when each spring is compressed singly, the inner junctures flex only after the outer junctures have flexed considerably. This creates a unique double-action, since the initial compression or partial deflection of the spring is soft, and occurs readily under a relatively light load, with flexure of the outer, thin, arcuate hinges. This is followed by a second partial depression, due to flexure about the inner junctures, but only under a substantially greater load.

More specifically, if each taipered spring is compressed individually, the largest diameter juncture, i.e., the uppermost hinge is the first to react. This is because the wall thickness of the hinge is the least on this bellow. After this upprmost bellow is deflected a small amount, resistance to further deflection becomes equal to the initial resistance to deflection of the adjacent bellow. Then, the next or second largest bellow begins to compress until its resistance increases to equal that of the third bellow. This sequential compression continues down to the smallest bellow which has the thickest outer juncture. Thereafter the spring begins to compress about the inner junctures which are substantially thicker and, therefore, offer greater resistance. The area about the largest diameter inner juncture begins to compress first and this sequential action continues down to the juncture of smallest diameter. As a concrete illustration, springs of the novel construction, mounted on a panel to form a mattress, but not intermeshed, would readily compress the initial amount under the weight of a body. Then localized springs would be compressed under bony parts of the body such as a hip, but with substantially greater resistance to deflection. This effect creates good comfort, yet without abrupt bottoming. This doubleaction is reduced considerably between intermeshed springs due to a normalizing effect to be discussed hereinafter, but is believed to be present even then to some extent depending upon the degree of intermeshing, to provide optimum comfort when balanced with other characteristics. It will be noted that when the springs are not intermeshed, each spring acts singly except for load distribution by the cover sheet.

The bellows springs can also be formed by rotational casting processes. However, blow molding is certainly preferred due to the unique structural features obtainable when employing blow-molding techniques, as explained herein.

For optimum intermeshing and stability, and for maximum compression without bottoming, the springs are preferably tapered lengthwise from one end to the other. This tapering causes the smaller diameter bellows to have a thicker outer hinge or juncture than the larger diameter bellows. This wall thickness variation occurs because the wall thickness decreases gradually with increasing distance from the center of the spring.

In the normal uncompressed state, the angle between the legs of each bellow should be greater than an angle of about 50 minimum to obtain a proper blow-molded hinge. If the angle is significantly less than this, the wall thickness of the outer arcuate hinge tends to be too thin because of the difficulty of forcing the polymer into the corresponding mold cavities. Thus, it is too weak to supply its share of support. Also, the bellows tends to have an insuflicient range of flexure, since the total flexure of each bellows is determined largely by the initial angle of separation of its legs. The combination of these two factors detrimentally lessens the spring support below a useful amount. However, it has been found that if the angle is about 50 or greater, when using the ordinary sharp apex on the outer juncture, the fiber stress in the plastic of the outer hinge becomes so great that a permanent set results.

Remarkably, it has been found that the novel arcuate outer hingle configuration actually enables these large angles to be employed yet without the occurrence of significant permanent set. This is believed to be because the flexing action occurs over the entire arcuate area rather than at a concentrated sharp apex. Whatever the technical explanation happens to be, the fact remains that these two normally incompatible, and very important characteristics are thus made completely compatible, thereby making bellows springs extremely useful.

This arcuate configuration has been found to be advantageous for other reasons also. This feature, coupled with others, causes the springs to have a spongy rather than an abrupt bottoming action under maximum compression. The resistance to compression increases with increasing load, and just prior to maximum compression, the resistance increases generally exponentially. Iie. the increase is rapid, but still at a rate, instead of instantaneously, so that a certain springiness remains even at the point of bottoming rather than a harsh, abrupt, unpleasant halt. This arcuate configuration is also of utmost importance for the squeezing and hinge bulging action occurring under load when the springs are intermeshed, as will be explained hereinafter.

While each of the bellows springs is shown to be generally circular in configuration, i.e. a tapered cylinder, each can conceivably be of polygonal cross-sectional configuration also.

Each of the hollow springs is freely vented to the atmosphere to allow the spring to readily vent the air therein and refill it. Thereby the walls and the hinges control and provide the compressible support of the springs.

Preferably, every one of these springs is attached to the support pad. However, in instances where certain of the tions in combinations of resiliency,

specifically,

springs are intermeshed or internested with other springs, only some need be attached. Thus, comparing the pad segment 26 in FIG. 3 with the number of springs mounted on pad 26' in FIG. 2, note that only nine connector Openings are provided, but that thirteen springs are mounted. The intermediate inverted springs 36 between the main upright springs 34 are held in the pattern relationship by being internested with springs 34 in the manner illustrated in FIG. 6.

The stretching capacity of the rubber support pad is important in combination with the bellows springs since it effects a complimentary give or shift of the support away from the body of the person for optimum comfort. The compression of the bellows springs is complemented by the flexing and stretching of the stretchable element. Yet the two coact to achieve a controlled resiliency without undue force concentration and with variable, controlled, reaction under load. The designer has almost complete freedom of support variation from portion to portion and in overall effect. This is because the variaload capacity, deflection per unit of load, total deflection, and other factors are practically without limit.

This stretching capacity is also important for another reason in the preferred form of the invention, since it allows easy attachment of the bellows springs. More referring to FIG. 3, the segment 26 there shown includes a plurality of openings 40 placed in pattern formation. These are preferably formed when the unit "is molded. Reinforcing each of these openings is a peripheral bead which preferably is formed of three like, separate arcuate components 42. These arcuate bead segments normally are inclose abutting, endto-end relationship with each other as illustrated in FIG. 3, to provide a complete peripheral support around the opening. These 'beads, shown more specifically in FIGS. 5 and 6, may be formed integrally with pad 26 or may be adhered thereto subsequently.

When stretching force is applied to the segment as illustrated at 26 in FIG. 4, the openings 40 are enlarged. This enables the enlarged head 50 on the lower end of each bellows spring 34 to be inserted through the opening, so that the smaller diameter neck portion 52 is in the plane of the pad. Release of the stretched pad allows the opening to contract to its original size so that the reinforced beads grip the spring neck 52 (FIG. 6). v The peripheral bead is purposely made in segments so that the openings can stretch uniformly with stretching of the sheet. If these were solid, excessive force would have to be locally applied to each bead to stretch it sufficiently. Further, undue stress would be placed on the rubber immediately around the openings.

It will be realized that the springs can be popped into place rapidly and conveniently using automated equipment. All that is needed is means to grip the resilient pad segment and expand it, and means to insert the springs. The insertion can be manual if desired.

As explained previously with respect to intermeshed springs 36, some of these need not be attached positively to the pad. However, as an alternative these may be attached as shown in FIG. 7. The inverted springs 36' in this case each have an enlarged head protrusion 56 and a smaller neck at the end adjacent the sheet pad 26'. The pad has extra openings for the inverted springs. It will be realized that when these springs to be internested are inserted in the pad, the pad has to be flexed into a curved configuration so that the springs radiate away from the pad at an angle with respect to each other. Then when the sheet is straightened the springs intermesh.

To assemble the novel apparatus, a plurality of molded pad segments 26 are formed with patterned openings. Segmental bead portions are formed around each open ing. The springs 34 are mounted to the pads by stretching each pad in the manner illustrated in FIG. 4, inserting the head and neck of the end enlargement, and releasing the pad to grip the springs as illustrated in FIGS. 6 and 8. Next the attachment rings 28 are applied to the pad peripheries. The segments are then interconnected using these rings, and the periphery of the entire pad means is connected to the respective peripheral frames 18 and 20 of the seat and back. The pads are therefore in tension.

The assembly is then covered with a cover layer material 15 (FIG. 6) to provide a support surface as well as aesthetic appeal. This cover layer 15 may be of any selected cloth or polymeric material, either solid or woven. It may constitute a single sheet or decorative material, or may include an underlying foam pad of a fraction of an inch thickness.

If desired, the periphery of the plurality of bellows springs may be enclosed with an undulated retention band like that illustrated and claimed in patent application Serial No. 348,927, entitled Spring Assembly, filed March 3, 1964 and assigned to the assignee herein. Mass production assembly can be achieved very readily.

In use, the compressive characteristics of each spring along its axis complement the pad stretching action. Moreover, any tendency of the sheet pad to present an unstable characteristic to the person sitting or resting thereon and any tendency of the pad to wrap around the person is cancelled out to any significant extent by the springs. That is, since each spring is capable of tilting, i.e., compressing on one side more than the other in response to an off-center load thereon, the springs together form a pocket to accommodate the shape of the person sitting thereon. Yet the pocket does not cause a wrapping effect around the person since the cover sheet 15 distributes part of the load to surrounding springs not contacted by the person. This effect is supplemented further if the springs are intermeshed, since a lateral action takes place between the intermeshed bellows of the springs. This action causes an increased support capacity due to three known effects.

The first eflect involves the expected cumulative resistance to deflection of the several springs due to individual hinge resistance to flexing under load. The second effect involves the frictional resistance between bellows of adjacent springs as they extend radially outwardly with compression and slide together. The third effect, and perhaps the most important is caused by an interference fit between the springs, and involves the necessity of the compressed bellows, and especially the arcuate outer ends, to bulge radially outwardly into the adjacent grooves, in spite of their increasing resistance to this action as the springs are squeezed further together, causing the free arcuate ends to constantly decrease in size. Each of these resistance forces increases markedly with each increment of further compression. All of these factors cooperate to achieve the final result. Consequently, an explanation of each factor, taken separately, is really incomplete. This is especially true with respect to the second and third factors which are closely interrelated.

Further, the springs cooperate uniquely with the flexible pad to bring out the best qualities and characteristics in each. No portion of the pad is unduly stretched or flexed in a manner to cause the springs to be uncomfortable. The springs never bottom in an uncomfortable manner, partially due to the give of the pad. The combination does not cause an unpleasant insecure feeling with shifting of a persons weight on the support. Further, the springs actually isolate the person from the pad so that any undesirable effects which would be created with the tendency of the pad to flex or shift or stretch are compensated for and cancelled out by the springs in a unique manner which cannot completely be explained. Actual tests on furniture units have shown the structure to be completely comfortable, practical, and relatively inexpensive.

Preferably, with this type of structure the hollow interior 35 of each spring is vented out through the neck and head by a central passage 37. This is preferable to the side outlet vents 39 since the air is vented completely out of the article of furniture rather than to the space intermediate the springs. This, therefore, eliminates any Swoosh noise when the air is vented intermediate the springs since it must find a means of escape out of the article seat or back. Therefore, the head enlargement serves a dual purpose of attachment and venting.

Several additional objects and advantages will become apparent to those skilled in this field upon studying the foregoing preferred form of the invention. Also, those with any imagination in this field will conceive of various obvious structural and design modifications to suit particular types of furniture, particular surroundings, and other various factors. These obvious modifications are deemed to be part of this invention, which is not to be limited to the specific detailed features of the preferred form shown, but only by the scope of the appended claims and the reasonably equivalent structures to those defined therein, if falling within the inventive concept.

I claim:

1. A resilient support comprising: a stretchable support layer; a plurality of upright, vented bellows springs substantially covering said layer in a pattern relationship with respect thereto; at least some of said springs having a knob protrusion at the end of adjacent said layer, and said layer including a plurality of openings to receive said protrusions for securing said springs; said openings being stretchable with said layer to increase in size to receive said protrusions; the inside of each spring being hollow and vented to the atmosphere, allowing unhindered air flow in and out; the walls of each spring being formed of a series of integrally joined individual bellows collectively providing the resilient support of the springs; each bellows formed by apair of outwardly converging legs having an outer juncture forming a resilient hinge biased to an expanded attitude; said bellows capable of being compressed varying amounts under load to flex said hinge, and of returning to the original expanded attitude upon removal of said load due to its inherent resilience, all without significant pneumatic hindrance from air in said spring.

2. An article of furniture comprising: a frame; a stretchable flexible support'layer having its periphery attached to said frame; a plurality of upright, vented bellows springs supported by said layer in a pattern relationship; at least some of said springs having a knob protrusion at the end of the spring adjacent said layer, said layer including a plurality of openings to receive said protrusions to secure said springs; said knobs each having an enlarged head and a smaller neck; and said openings each being expandable with stretching of said layer to pass the head of a respective spring knob to retain the spring around its neck upon relaxation of said layer; the inside of each spring being hollow and vented to the atmosphere, allowing unhindered air flow in and out; the walls of each spring being formed of a series of integrally joined individual bellows collectively providing the resilient support of the springs; each bellows formed by a pair of outwardly converging legs having an outer juncture forming a resilient hinge biased to an expanded attitude; said bellows capable of being compressed varying amounts under load to flex said hinge, and of returning to the original expanded attitude upon removal of said load due to its inherent resilience, all without significant pneumatic hindrance from air in said spring.

3. A resilient support comprising: a peripheral frame; a rubber-type stretchable flexible, tension-type, load supp sheet me ns att ched at it P r p e y to Said frame;

said sheet means having peripheral connectors attached to said frame to suspend it and any load thereon; a plurality of hollow, vented, polymeric bellows springs supported on said sheet means; said springs having internested bellows with surrounding springs; at least some of said springs having axial protuberances adjacent said sheet means, including an enlarged head and a smaller neck, and said sheet means having a plurality of receiving openings corresponding in pattern to said protuberances; each of said openings including peripheral reinforcing bead means formed of a plurality of independent, arcuate bead portions, and forming an opening of smaller size than one of said heads; said openings being expandable with stretching of said sheet means to pass said heads for retention of said springs; and cover means over said springs opposite said sheet means incorporating the assembly into a unitary support; the inside of each spring being hollow and vented to the atmosphere, allowing unhindered air flow in and out; the walls of each spring being formed of a series of integrally joined individual bellows collectively providing the resilient support of the springs; each bellows formed by a pair of outwardly converging legs having an outer juncture forming a resilient hinge biased to an expanded attitude; said bellows capable of being compressed varying amounts under load to flex said hinge, and of returning to the original expanded attitude upon removal of said load due to its inherent resilience, all without significant pneumatic hindrance from air in said spring.

4. A resilient support comprising: a rubber-type, stretchable flexible, tension-type, load support sheet means; a plurality of polymeric bellows springs supported on said sheet means; at least some of said springs having axial protuberances adjacent said sheet means, including an enlarged head and a smaller neck, and said sheet means having a plurality of receiving openings corresponding in pattern to said protuberances; each of said openings including peripheral reinforcing bead means formed of a plurality of arcuate bead portions and forming an opening of smaller size than one of said heads; said openings being expandable with stretching of said sheet means to pass said heads for retention of said springs; the inside of each spring being hollow and vented to the atmosphere, allowing unhindered air flow in and out; the walls of each spring being formed of a series of integrally joined individual bellows collectively providing the resilient support of the springs; each bellows formed by a pair of outwardly converging legs having an outer juncture forming a resilient hinge biased to an expanded attitude; said bellows capable of being compressed varying amounts under load to flex said hinge, and of returning to the original expanded attitude upon removal of said load due to its inherent resilience, all without significant pneumatic hindrance from air in said spring.

References Cited by the Examiner UNITED STATES PATENTS 2,350,711 6/1944 Amos 5348 2,686,006 8/1954 Hasselquist 5-348 2,818,974 1/ 1958 Talbot 206 2,897,520 8/1959 Bradford 5-348 2,979,739 4/1961 Krakauer 5345 3,171,691 3/1965 Buehrig 5345 FOREIGN PATENTS 1,148,718 5/1963 Germany.

FRANK B. SHERRY, Primary Examiner. C, A. NUNBERG, Assistant Examiner,

Claims (1)

1. A RESILIENT SUPPORT COMPRISING: A STRETCHABLE SUPPORT LAYER; A PLURALITY OF UPRIGHT, VENTED BELLOWS SPRINGS SUBSTANTIALLY COVERING SAID LAYER IN A PATTERN RELATIONSHIP WITH RESPECT THERETO; AT LEAST SOME OF SAID SPRINGS HAVING A KNOB PROTRUSION AT THE END OF ADJACENT SAID LAYER, AND SAID LAYER INCLUDING A PLURALITY OF OPENINGS TO RECEIVE SAID PROTRUSIONS FOR SECURING SAID SPRINGS; SAID OPENINGS BEING STRETCHABLE WITH SAID LAYER TO INCREASE IN SIZE TO RECEIVE SAID PROTRUSIONS; THE INSIDE OF EACH SPRING BEING HOLLOW AND VENTED TO THE ATMOSPHERE, ALLOWING UNHINDERED AIR FLOW IN AND OUT; THE WALLS OF EACH SPRING BEING FORMED OF A SERIES OF INTEGRALLY JOINED INDIVIDUAL BELLOWS COLLECTIVELY PROVIDING THE RESILIENT SUPPORT OF THE SPRINGS; EACH BELLOWS FORMED BY A PAIR OF OUTWARDLY CONVERGING LEGS HAVING AN OUTER JUNCTURE FORMING A RESILIENT HINGE BIASED TO AN EXPANDED ATTITUDE; SAID BELLOWS CAPABLE OF BEING COMPRESSED VARYING AMOUNTS UNDER LOAD TO FLEX SAID HINGE, AND OF RETURNING TO THE ORIGINAL EXPANDED ATTITUDE UPON REMOVAL OF SAID LOAD DUE TO ITS INHERENT RESILIENCE, ALL WITHOUT SIGNIFICANT PNEUMATIC HINDRANCE FROM AIR IN SAID SPRING.

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