WO1995013728A1

WO1995013728A1 - Flexible support, such as a mattress, a chair seat or the like

Info

Publication number: WO1995013728A1
Application number: PCT/NO1994/000177
Authority: WO
Inventors: Johan Caspar Falkenberg
Original assignee: Nail-Web A.S.
Priority date: 1993-11-16
Filing date: 1994-11-08
Publication date: 1995-05-26
Also published as: NO934149L; NO178562C; NO934149D0; NO178562B

Abstract

A flexible support, for instance a mattress, a chair seat or the like has a core of mechanical springs (31) provided between a lower and upper supporting plane (34, 34'). When a body is placed on the support, it is wanted a uniform and flexible transfer of the body weight. In order to achieve this the springs (31) are composed of spring elements, preferably lengths of spring strip steel or another suitable strip or wire-shaped material, which are provided with their attachment points (11) predominantly perpendicular between the two supporting planes and whose axis is slightly curved or bent in its longitudinal direction. The spring elements will thus have an eccentricity over the entire or a part of the length in relation to the line between the attachment points, with the result that during vertical loading they obtain a horizontal deflection in an intended direction and accompanied by a vertical depression of the springs.

Description

Flexible support, such as a mattress, a chair seat or the like

The invention concerns flexible support, for instance a mattress, a chair seat or the like, said support having a core of mechanical springs provided between an upper and a lower supporting plane. The invention also concerns a spring element for a support of this kind. Finally the invention also concerns a stay element for transverse stays in a support of this kind, especially where the support is horizontally braced and the depression of the springs is restricted.

The core of mechanical springs in such flexible supports is attached on the top to a padding sheet of a soft material, such as foamed plastic or foam rubber and on the bottom it can be attached to a corresponding sheet or alternatively to a supporting framework.

With the term flexible support, it is understood any support which is ment for supporting a body so that the rest pressure of the body against the support will be uniformly distributed. Primarily it is referred to the support or bearing of a human body, as on a mattress, on a sofa or a chair, but the support may also be a back or side support. The term flexible support is also ment to cover supports for other types of bodies, i.e. any object, by which it is important to have a flexible, force or pressure unifying support.

With respect to the prior art, as a basis, reference is made to mattress constructions, which seems to be the construction closest to the present invention.^' The object of the invention and the advantages achieved may also best be illustrated through this example, which shall not be limiting the scope of the invention.

One disadvantage of the known support constructions, for instance in the form of mattress designs, is that during use they fail to exert on the various parts of the body a pressure which would correspond to the greatest possible extent to the pressure acting on these bodily parts when the body is floating in water in a horizontal, natural position. In such a case a buoyant force would be exerted on each part of the body corresponding to the weight of the bodily part concerned and this bodily part thus does not need to support or burden adjoining parts with the consequent creation of tensions.

Known mattress designs do not in any way fulfil this ideal. In order to limit the degree to which the body sinks down in a water bed, the greatest part of the body's weight is taken up by tension in the material of the mattress and a water mattress therefore acts like a hammock with a certain water pressure on the bottom. Thus the pressure under the lowest-lying parts of the body such as the buttocks and shoulders becomes disproportionately great in relation to the pressure under the lower back.

The same applies to a spring mattress where the pressure against the body is provided by coil springs where force and depression of the springs are linearly proportional. In a well adapted spring mattress the buttocks will sink to approximately 8-10 cm below the surface plane. In the natural resting position the lower back should then be 4-5 cm higher. This means that the springs under the buttocks should provide double the amount of counterpressure compared to the springs under the lower back. This situation is further reinforced by the fact that, due to the padding and the inevitable interaction or interference between adjoining springs, the lower-lying parts of the body "pull after them" a larger part of the adjacent springs than the body's higher- lying parts, with the result that in practice the pressure under the buttocks can be up to three times as great as the pressure under the lower back. Thus the support under the lower back becomes insufficient and muscle tensions will easily arise.

When the body is floating in a horizontal, natural position in water, the buttocks, e.g., will sink to a depth of approximately 25 cm and the lower back to a depth of approximately 20 cm, thus giving a pressure under the buttocks of 25 N/dm² and 20 N/dm² under the lower back, in other words a fairly even pressure distribution.

The object of the present invention, therefore, is to provide a flexible support, for instance a mattress which exerts a pressure against the various parts of a body which to the greatest possible extent corresponds to the pressure which acts on these various parts when such a body is floating in water in a horizontal, natural position. A further object of the invention is to avoid the disadvantages which exist in the present, known mattress designs.

These and other objects are achieved with a flexible support which, according to the present invention, is characterized by the features defined in the patent claims.

Further features and benefits of the support according to the invention are characterized by the features presented in the independent claims.

A spring element for implementing the flexible support according to the invention is characterized by a spring element formed from a piece of hardened spring strip steel, the ends of which spring element are provided with notches or holes for fastening to the supporting plane of the flexible support.

A stay element for implementing the support according to the invention is characterized by a stay element formed with a middle part and bent or splitted end parts or arms beginning some distance inwards from each end. The middle part may be a tube piece, and the end parts or arms may be provided by flat, splitted, spring steel elements, the arms of the stay elements may in a further embodiment of the invention be formed by bending the split end pieces of a strip steel element in opposite directions, obliquely downwards and obliquely upwards respectively, the end sections of the arms being bent back to the horizontal direction and provided with mounting holes, and the horizontal central section of the stay element being braced by means of profiling.

The invention will now be described in more detail with reference to embodiments which are illustrated in the attached drawing.

Fig. 1 illustrates a spring element according to the invention.

Fig. 2 illustrates a diagram for the ratio between load and depression of the springs of the spring element in fig. 1.

Fig. 3 illustrates the spring element in fig. 1 used in an embodiment of the invention in the form of a mattress.

Fig. 4 is a plan view of a mattress according to the invention, with the upper padding sheet of the mattress removed.

Fig. 5 is a cross section through the mattress according to the invention, viewed along the line 5-5 in fig. 4.

Fig. 6 is a longitudinal section through the mattress according to the invention, viewed along the line 6-6 in fig. 4.

Fig. 7 is a simplified longitudinal section corresponding to the longitudinal section in fig. 6, with the springs of the mattress according to the invention in a partially depressed condition. Figs. 8a-c illustrate a stay element used as a transverse stay in the support according to the invention.

Figs. 9a-c illustrate a second embodiment of the stay element in fig. 8.

Figs. 10a,b are a sectional elevation and a side view respectively of the spring element in fig. 3.

Figs. 11-14 illustrate alternative versions of spring elements for use in a support according to the invention and made of a wire material.

In the drawings it is, as a non restricting example of a flexible support according to the invention, referred to a mattress.

Fig. 1 illustrates a spring element 10, hereinafter called a "floating spring" in the form of a thin leaf spring of tempered strip steel or another suitable material, such as fibre- reinforced plastic. The spring element 10 is slightly curved or alternatively provided with one or more bent plane sections, thus causing the spring's longitudinal centre line to form a curve which at least over a section of this centre line deviates in relation to the axis 11 between the spring element's end points. This deviation can have a maximum value e at the central section of the spring element or floating spring 10, while the floating spring's end points are secured against substantial horizontal displacement. When the springs are depressed they will not be able to move further than permitted out of plumb.

If the floating spring 10 is straight, i.e. e = 0, and is exposed to an increasing axial pressure P, the spring will remain straight until P reaches a critical value

.2

^PCR~^π El

where E is the material's modulus of elasticity, and I is the moment of inertia for the cross section about the axis of deflection which is perpendicular to the paper plane and given by the expression

b - t³ 12 for a leaf spring with thickness t and breadth b. When P reaches the critical value P_CR, the spring will bend in the lateral direction and for a relatively small increase in P obtains a rapidly increasing deflection and depression of the springs Y, the curve which expresses the correlation between the depression of the springs and the pressure P being^* indicated by the dotted line 1 in fig. 2.

If the spring is given a small initial deflection e as illustrated in fig. 1 , the correlation between depression of the springs and force will be in principle as shown by the curve 2 in fig. 2, i.e. a slow increase will be obtained in the depression of the springs, but a rapid increase in the force in a first phase, whereupon the depression of the springs rapidly increases with a small increase in the force in the next phase which is described as "the floating phase" and is indicated by S in fig. 2. The extent to which the curve 2 deviates from the curve 1 will depend on the initial eccentricity e, which in the case of the present invention may suitably be 2-5% of the length of L of the floating spring 10. The linear spring characteristic is illustrated by the curve 3 on the curve 2 and this illustrates very clearly that the floating spring 10 according to the invention has an essentially non-linear characteristic which helps to give the spring element the qualities desirable for implementing the present invention.

Floating springs 10 of the above-mentioned kind can constitute the spring core in a flexible support according to the invention, for instance a mattress, the said springs being glued with their ends against a lower and an upper sheet 34 and 34' respectively of foamed plastic, as shown in fig. 3. Here the spring element 10 is designed as a leaf spring 31 , the ends of which are designed to ensure that the adhesive 33 is securely fixed to the sheets 34, 34'.

The adhesive 33 can preferably be a fusible adhesive. The leaf spring 31 is also illustrated in more detail in fig. 10, where the design of the ends of the leaf springs can be clearly seen. On the side to which the springs 31 are attached, there is glued or laminated to the sheets 34, 34' a woven fabric 35, 35' which reinforces the sheets around the attachment point of the spring while simultaneously also ensuring that the adhesive is well fixed. With a view to this the woven fabric 35, 35' may have a rather open structure, thus allowing the glue to penetrate in between the threads of the fabric and adhere to them. Instead of a fabric, also elastic strips may be used.

An embodiment of a mattress according to the invention and provided with floating springs 10 as described above is illustrated in figs. 4-7, where the floating springs 10 are indicated by 31. Fig. 4 is a plan view of the mattress with the upper padding sheet 34' removed and illustrating the spring elements 31 arranged in rows in the mattress's transverse direction, the spring elements 31' thus being deflected to the right of the figure and the spring elements 31" being deflected to the left, illustrated by the arrows 70' and 70" respectively. As shown, the spring elements 31" are provided horizontally displaced in relation to the springs 31 , thus preventing springs in two adjacent rows from touching one another when the depression of the springs causes them to be bent towards one another.

Between two rows of springs 31' and 31" which are deflected from each other, there is provided a stabilizing, transverse stay 36, as shown in sectional elevation in fig. 5 and which will be described in more detail with reference to figs. 8 and 9. At their four end points the stays 36 are connected with longitudinal edging strips 37, 37', preferably formed from strip steel, which extend along the lower and upper longitudinal edges of the mattress and are connected at their end points with transverse end bars 39, 39', as illustrated in figs. 4 and 6. The end bars 39, 39' can be made of profiled strip steel or laminated wood.

The object of the transverse stays 36 is first of all to transfer transverse horizontal loads in the upper plane, illustrated by F in fig. 5, down to the lower plane and over into the underlying, supporting bed construction. Secondly, the horizontal central sections of the transverse stays which are located in the mattress's median plane, help to restrict the deflection of the springs 31, thus preventing them from, being overloaded and becoming permanently deformed. This is best illustrated in fig. 7, where it can also be seen that with the springs positioned in a pattern as described above, interference between the spring elements 31 and the stay 36 is avoided.

The mattress is closed along the longitudinal edges with edging elements 38 and along the end edges with edging elements 40. The elements 38, 40 are preferably made of a soft foam material and glued to the respective longitudinal edging strips 37 and end bars 39, as well as to the edges of the foam sheets 34, 34^*.

Fig. 8 shows a version of the stay element or transverse stay 36, consisting of a middle or center part 81 formed of a stiff tube open in both ends, and two sets of pieces of strip steel 36' and 36" inserted in each end of the tube 81. The pieces of strip steel are joined for instance by welding at one end, while the other end sections are bent obliquely downwards and obliquely upwards respectively. The outermost end of the oblique end sections is bent back to a horizontal position and provided with a holes 82 for attachment to the longitudinal edge strip 37. Figs. 8b and 8c show two possible variants of connections between the steel strips 36', 36" and the horizontal central section, viewed along lines A-A or B-B in fig. 8a. By squeezing together the tube 81 as shown on the left side of figs. 8a and 8b, the strips will be fixed in the tube in an easy way. As shown in fig. 8c and on the right side of fig. 8a, the connection between tube and the elements 36', 36" may also be provided through rivets, welding or the like.

Figs. 9a-c illustrate an alternative embodiment 90 of the stay element or transverse stay 36 with the advantage that the stay element is formed from a single piece of strip steel, thereby avoiding the welding operation. A further advantage of this design is that the individual stay elements 90 can be nested into one another during transport and storage, thereby occupying less volume. Fig. 9 shows the stay element 90 in a plan view, the stay element 90 being split from the end points along the centre line and some distance inwards from each end, thus forming arms 94', 94" which are bent downwards and upwards respectively about the line 92. The end sections 94', 94" are provided with holes 96 and bent in the opposite direction to the arms about the line 95, so that they are substantially horizontal and can form a flat abutment against the longitudinal edge strips 37', 37". The stay elements' horizontal central section can have a reinforcing profile as illustrated in the section in fig. 9c.

Fig. 10 illustrates a preferred embodiment of a floating spring 31 formed from a piece of reinforced strip steel. The ends of the floating spring 31 are equipped with a central tongue-shaped section 102 and two shorter tongue-shaped sections 101 , separated by rounded notches 103. This design makes it possible to cold press on to the end of the spring an adhesive element 33 in the form of a cut-off fusible adhesive string. The tongue 102 is pressed through the diameter of the adhesive element, while the shorter, tongue-shaped sections 101 are pressed some distance into the adhesive element 33, thus preventing this from being completely split. When the floating spring 31 is subsequently glued to the textile-coated sheets 34,34' as illustrated in fig. 3, local heat is applied to the end section of the floating spring 31 , thus causing the adhesive element 33 to be fused into the fabric 35, 35'.

The spring elements can also be provided straight, i.e. with e = 0, and in this condition they are glued between the supporting plates 34, 34', whereupon the spring elements are given a bend or deflection about their horizontal centre axes, with the result that when they are loaded they are deflected in the desired direction, as illustrated in fig. 4. Figs. 11-13 show alternative versions of floating springs, all of which are made of a wire material (spring wire). Fig. 11 shows a slim screw spring 111 with a relatively large pitch and with its ends provided with loops or hoops which have an eccentricity e in relation to the rectilinear spring axis 112. Fig. 12 illustrates a second spring element in the form of a coiled wire 121 where the coils can be open or closed, as in the case of corset springs. The coils lie in a slightly curved or bent plane, the spring element 121 thus obtaining a controlled deflection. Here too hoops are used on the ends of the spring element 121 for attachment to the sheets 34,34' in the mattress according to the invention.

Fig. 13 illustrates a spring element in the form of a rolled flat screw spring 131 of a type which is used, amongst other things, in camping stool seats.

Figs. 14a-b illustrate a floating spring 140 which, in the same way as that illustrated in fig. 10, is formed from a piece of reinforced and slightly curved strip steel, but each end of which is provided with an oblong transverse hole 141. The object of this design is to enable the spring to be attached to the reinforced foam sheet 34, firstly by applying a small quantity of fusible adhesive 142 in the form of a button or a short string, after which the end of the spring is stuck down into the hot glue, thus causing it to flow in and fill the hole 141 , thereby locking the end of the spring in the glue 142 which is again attached between and under the wires in the relatively open fabric 35.

An alternative to this is to use a shoe 143 at each end of the spring 31. Such a shoe may be glued to foam sheet or the fabric before positioning the floating spring 140, whereupon the spring is fitted into the shoe 143 and held in position by a knot 144 extending through the hole 141. This will be favourable for automatic production. In fig. 14d a variant is shown, in which the shoe 143 has a bottom foot element 146 which is glued to the foam sheet between the shoe 143 and the foot element 146 there is a narrow part 145 which may bend and fuction as an integral hinge. In this way the influence from the movement of the spring on the foam sheet will be reduced.

As mentioned above in connection with fig. 3, the object of the glued on or laminated woven fabric 35, 35' is to attach the spring 31 and reinforce the foam sheet 34, 34' locally around the spring attachment. At the same time the woven fabric 35 helps to restrict the elastic axial deformation in the horizontal plane of the upper foam sheet 34' and thereby limit the displacement of the top points of the springs, thus preventing the spring elements from coming further than permitted out of plumb. However, it is desirable that the woven fabric 35' should permit a certain amount of elastic stretching of the foam sheet 34', thus enabling it to form hollows for the various parts of the body without behaving like a taut hammock. This may be achieved simply by using a stretch fabric. An alternative is also that the woven fabric 35' is glued on to the foam sheet 34' in such a manner that it can expand somewhat before the woven fabric 35' tautens and stops the movement. This can be achieved by stretching the sheet 34' in the longitudinal direction and/or the transverse direction before the woven fabric 35' is glued on, the woven fabric 35' then being glued to the sheet 34' while it is under tension. When the tension is released after the woven fabric 35' has been glued on, the sheet 34' will contract and the woven fabric 35' will form a finely distributed wrinkle pattern which permits a certain limited degree of elastic stretching or extension of the sheet 34' until the wrinkles or crimping have been smoothed out, preventing further stretching.

With a mattress formed according to the present invention which employs spring elements according to the present invention, a substantial improvement is obtained in relation to the mattress constructions known at present, the spring elements according to the invention having a non-linear ratio between force and depression of the springs, since the spring force increases rapidly in an initial phase of the depression of the springs, followed by only a slight increase during a further depression of the springs, a spring which is compressed by, for example, 8 cm thereby exerting a pressure on the body which is normally only 15-20% greater than a spring which only has half the depression of the springs.

Moreover, in the mattress formed according to the present invention the springs are mounted in such a manner at their upper and lower end points that in practice they offer no resistance to lateral movements and furthermore there is no interconnection between adjoining springs apart from the soft and elastic padding sheet to which they are attached, thus achieving a high degree of independence between the individual spring elements in the mattress. A mattress is thereby obtained which provides a much more even pressure distribution against the body of a user of the mattress and the mattress also attains far better "sensitivity", i.e. ability to shape itself according to the body, than that obtained with the conventional mattresses used hitherto where the spring elements have a linear characteristic.

Many modifications of the invention are possible within the scope of the claims, both with respect to construction details and type of flexible support being produced. Such details may be the use of a stretchable woven fabric, the amount of glue used and the penetration into or through the fabric, use of shoes, etc. As mentioned earlier other types of flexible supports than mattresses are within the scope of the invention. Such supports may be chairs and sofas. The support may be used for all purposes where a uniform and flexible support is wanted.

Claims

PATENT CLAIMS

1. A flexible support, for instance a mattress, a chair or the like, which support has a core of mechanical springs (31) provided between a lower and an upper supporting plane (34, 34'), cha racterized in that the springs (31) are composed of spring elements, preferably lengths of spring strip steel or another suitable strip or wire-shaped material, which are provided with their attachment points (11) predominantly perpendicular between the two supporting planes and whose axis is slightly curved or bent in its longitudinal direction, the spring elements thus having an eccentricity over the entire or a part of the length in relation to the line between the attachment points, with the result that during vertical loading they obtain a horizontal deflection in an intended direction and accompanied by a vertical depression of the springs.

2. A flexible support according to claim 1, cha racterized in that the lower and/or upper supporting plane (34, 34') are composed of a sheet of a soft material, such as foam material to which on the side which faces into the mattress there is laminated a woven fabric (35, 35'), for instance a stretchable fabric, or elastic strips, to which the ends of the spring elements (10; 31) can be attached, preferably by means of fusible adhesive.

3. A flexible support according to claim 2, cha racterized i n that the spring elements (10; 31) are composed of pieces of reinforced spring strip steel which is provided at at least one of its ends with notches (103) or holes for attachment to the support's lower and/or upper supporting plane (34, 34").

4. A flexible support according to claim 2, ch a ra cterized i n that the spring elements are composed of slim, coil springs (111) with a relatively large pitch.

5.. A flexible support according to claim 2, ch a ra cte rized i n that the spring elements are composed of a wire (121) which is bent in open or closed coils which are substantially located in the same plane.

6. A flexible support according to claim 2, ch a ra cterized in that the spring elements are composed of rolled flat coil springs (131).

7. A flexible support according to one of the preceding claims, ch aracterized in that the spring elements (31) are provided with their axis of deflection in the support's transverse direction and regularly in pairs of rows, that there is provided a transverse stay (36) between respective pairs of rows, that the springs (31') in one row of the pair are displaced in the support's transverse direction in relation to the springs (31") in the second row of the pair, and that the spring elements (31) are arranged in such a manner that during depression of the springs they are deflected away from the transverse stay (36).

8. A flexible support according to one of the preceding claims, ch a racterized in that the lower ends of the spring elements are attached to a supporting framework.

9. A flexible support according to one of the claims 1-9, wherein the upper and lower supporting planes are sheets (34, 34') of foam material, and wherein the sheets (34, 34') are connected to longitudinal edge walls (38) of foam material, ch a racte rized in that a pair of lower and a pair of upper longitudinal edging strips (37, 37') are attached between the sheets (34, 34") and the edge walls (38), the ends of the longitudinal edging strips (37, 37') being connected to respective transverse lower and upper end edge bars (39, 39'), that a row of transverse stays (36) are provided, the central section of the stays being located in or near a plane halfway between the sheets (34, 34'), and that the ends of the stays (36) are attached to the upper and lower longitudinal edging strips (37, 37') respectively, the ends of the stays being composed of a pair of arms (36', 36"; 91', 91") respectively, bent in opposite directions, one arm (36; 91) in a respective pair extending downwards for attachment to the lower longitudinal edging strip (37) and the second arm (36", 91") extending upwards for attachment to the upper longitudinal edging strip (37').

10. A spring element (10, 31) for a flexible support according to claim 1 or 2, with a core of mechanical springs (31) provided between an upper and a lower supporting plane (34, 34'), ch a ra cterized in that the spring element (10, 31) is formed from a piece of reinforced spring strip steel, the ends of which are equipped with notches (103) or holes preferably in an oblong transverse hole for attachment to the flexible support's supporting plane.

11. A spring element according to claim 10, characterized in that in its longitudinal direction it is in the shape of a 5 curve which deviates from the straight line between the ends of the element, thus giving it a deflection perpendicular to the axis in an intended direction during axial pressure loading.

12. A spring element according to claim 10 or 11,

<\Q characterized in that the support on the surface facing the spring element, or the spring element on the end points are provided with a quantity of fusible adhesive, the end points of the spring element possibly having been provided with end shoes.

•15 13. A stay element for horizontal bracing and restriction of the depression of the springs in mattresses with a core of mechanical springs (31) provided between an upper and a lower supporting plane (34, 35'), characterized in that the stay element (90) is formed from a sentral, firm element, between pieces of strip steel which is split some distance inwards from each end, the stay element's arms (91', 91") being formed by bending the split end pieces of the strip steel in opposite directions, obliquely downwards and obliquely upwards respectively, that the arms' end sections (94^*.94") are bent back to the horizontal direction and provided with mounting holes (96), and that the horizontal central section of the stay element (90) preferably is made of a piece of tube.