EP0796580A1 - Spring core for cushion - Google Patents

Abstract

The core comprises a large number of springs (4) which are inserted in the central foam body (3), on which there are covering layers. The body is profiled on both sides and has protrusions (5) and recesses of a mating geometrical shape. The springs are accommodated in the recesses. Parallel ribs, which can be of trapezium or rectangular cross-section, can be formed on both sides of the body, and spiral springs can be used, their ends resting on the protrusions. The covering layers (2) can be glued to the protrusions, with the spring ends between them. The spring ends can be 60 mm. diameter, or the springs may be of a double-cone shape.

Description

The present invention relates to a spring core according to claim 1 and in particular to a multi-layer spring core with a central foam body, in which a plurality of spring elements are used, and a cushion element with such a spring core.

Such spring cores are used in the furniture industry and are used in particular as a core element in mattresses or upholstered furniture. These core pieces are decisive for the lifespan and hardness of the pieces of furniture and are usually provided with a cushion layer that determines the lying or sitting comfort before they are covered with a firm drill. In the case of modern innersprings, synthetic foams are increasingly being used in addition to foam rubber or foamed latex for reasons of cost. Unfortunately, the compression hardness and thus the spring force of these foams noticeably diminish after a short time, making them unsuitable for use in heavily used furniture. Improved spring cores therefore consist of a combination of foam and spring elements.

For example, spring cores are used today in railroad or airplane seats, in which metallic springs are directly foamed in a foam body. In this way, the service life can be extended compared to pure foam innersprings; However, comfortable and inexpensive seating or reclining furniture cannot be manufactured with it. The direct foaming in of the spring elements requires complex machine tools and increases the cost of manufacture, especially in the case of smaller production quantities. In addition, it has proven essential for the comfort of reclining and seating furniture that they have good point elasticity, that is to say they have a pronounced local spring force. By foaming the spring elements, however, these are coupled to one another and can therefore no longer be a local load profile independently of one another consequences. In addition, the foam in the area of the metallic spring elements suffers from this type of composite spring cores and these composite spring cores often have to be replaced when used heavily.

It has therefore already been proposed to punch cylindrical cavities out of a central foam body and to insert spiral spring elements into these punch holes. This central foam body is covered on both sides with thinner foam layers, so-called cover layers. This ensures on the one hand that there is no substantial spring coupling between the individual spring elements and that the spring core can act in a desired manner in a point-elastic manner. In a more comfortable embodiment, a thin fiber or needle fleece is glued in between the central foam body and the foamed cover layers as a cushion carrier. Unfortunately, this type of combined innerspring also shows undesirable signs of wear on the cover layers after prolonged use. Upholstery carriers in the contact area of the individual spring elements and a considerable amount of foam residues accumulates in the production of such spring cores, which can not be used easily.

With today's living and sleeping habits, in addition to the pleasantly felt point elasticity, there is also the desire for thin and light cushions. On the one hand, these should not spring back and on the other hand should also retain their shape over the long term. Unfortunately, it turns out that in the case of such thin upholstery with combination spring cores, their metallic spiral springs are compressed in such a way that their individual turns collide directly when subjected to heavy loads. This leads to undesirable metallic noises, especially when using interconnected spring elements (Bonel systems).

It is therefore an object of the present invention to provide an inexpensive and low-wear cushion core with good point elasticity, which is suitable for use in thin cushion elements. In particular, a combination spring core with a central foam body is to be created, in the production of which no systematically generated waste pieces are produced and with which spring core silent and freely dimensionable cushion elements can be produced.

This object is achieved according to the invention by a spring core with the features of claim 1. The central foam body is profiled on both sides in a special way, i.e. the elevations and depressions of the respective profile have a complementary geometric shape. Spring elements, preferably metallic spiral springs, are used at those points where depressions lie opposite one another. This special shape of the central foam body and the spiral springs used also ensures that the spring elements are installed in the correct position within this foam body, since these spring elements are shaped and dimensioned such that their ends rest on the elevations of the foam body profile. In a preferred embodiment, the spiral springs are preloaded and can be clamped onto the elevations of the foam body profile.

The construction according to the invention leads to the fact that when the cover layers, respectively. Upholstery carrier, also called cover layers below, on the foam body, the ends of the spiral springs between these cover layers and the foam body are held. Spiral springs used and fixed in this way lie next to each other precisely and without contact even after intensive and prolonged use and cannot rub against the cover layers. Your vibration behavior can by the Foam body and the top layers are damped in the desired manner. The double-conical shape of the spiral springs on the one hand and the foam part in the middle prevent the individual spiral flights of the spiral springs from resting on top of one another under extreme loads or low installation heights.

According to the invention, the elevations of the foam body profile are formed on both sides as parallel ribs. These ribs have a complementary geometric shape to their gaps, whereby low-waste production can be realized and the production costs can be reduced. In addition, these ribs have a stiffening effect in their longitudinal direction and at the same time allow the spring core to be bent in the transverse direction without great effort, as is desired in the case of beds with adjustable head and / or foot ends. When bending, the cushion layer can escape into the spaces between the ribbed foam body and thus increases the flexibility of the entire cushion element transverse to the direction of the ribs.

The individual fixation of the spring elements in the spaces between these ribs also creates optimal point elasticity and the spring core can be assembled in a simple manner, i.e. cut into desired sizes.

Further advantages of this type of low-wear combination spring cores are immediately apparent to the person skilled in the art and can be seen not only in the waste-free production method and the free dimensioning, but also in particular in the silent functioning and the improved cross ventilation. With conventional combination spring cores, the air in the cavities cannot circulate freely and does not escape when loaded always silent. The construction according to the invention allows good ventilation of the entire cushion element.

It goes without saying that the physical properties of the foam used for the foam body or the cover layers are selected in a desired manner by a person skilled in the art and the spring strengths or. Spring shapes can be adapted to the desired requirements. In particular, individual springs can be combined into spring groups in order to be able to correspond to an individual load profile or additional cushion or spring layers can be provided.

Fig. 1

ein Kombinations-Federkern bekannter Art;

Fig. 2

eine bevorzugte Ausführungsform eines erfindungsgemässen Kombinations-Federkerns;

Fig. 3

ein Ausschnitt aus der in Fig, 2 dargestellten bevorzugten Ausführungsform.

The invention will be explained in more detail below with the aid of an exemplary embodiment and with the aid of the figures. It shows:

Fig. 1

a combination spring core of a known type;

Fig. 2

a preferred embodiment of a combination spring core according to the invention;

Fig. 3

a section of the preferred embodiment shown in Fig. 2.

The spring core 1 of known type shown in FIG. 1 has a central foam body 3 which is provided with cover layers 2 on both sides. An elastic adhesive layer 12 ensures the connection between the cover layers 2 and the foam body 3. These cover layers 2 can consist of a simple foam layer or additionally comprise a nonwoven layer. The foam body 3 has cylindrical recesses 6, in which spring elements 4 are inserted. When this spring core is subjected to a local load, the individual springs are coupled to one another by the solid foam body 3 and by the relatively stiff fiber fleece, ie they cannot really be point-elastic Act. Foams are not only synthetic products but also natural foam rubber or foamed latex.

In contrast, Figure 2 shows a central foam body 3, which is provided on both sides with a rib-shaped profile, the elevations 5 and depressions 7 have a complementary geometric shape. In the illustrated embodiment, the cross section of the rib-shaped profile is trapezoidal and has a wider base towards the central part. It goes without saying that this trapezoidal cross section can also be designed such that the wider base lies on the side of the cover layers 2. The spring elements 4 are mounted in the respective recesses 7, i.e. are not coupled together by the foam body 3 and ensure good point elasticity. The individual spring elements 4 are adapted to the flank profile of the profile and have a biconical shape in the embodiment shown. In order to ensure the exact positioning of the springs within the spring core, the winding ends of the individual spring elements 4 protrude above the elevations 5 and rest on the end faces 11 of these elevations.

The respective cover layers 2 are glued to the end faces 11 of the elevations 5 of this profile. Through this gluing, the spring ends are held in their position and cannot slide out of their position and touch each other, even in the event of extreme compressions or deflections of the entire spring core. In addition, this fixation prevents the spring elements from rubbing against the cover layers and damaging them after prolonged use. The ribs running parallel to one another on both sides of the foam body 3 lead on the one hand to a stiffening of the entire spring core in the direction of the ribs 5 and at the same time to a greater flexibility transversely to this direction. The complementary is essential to the invention Geometric shape of the elevations 5 and depressions 7 of the profile, since there is no undesired cutting waste during the production of this central foam body 3. This special geometric design also leads to cross ventilation, which facilitates the noiseless escape of air under extreme loads.

Figure 3 shows a section of the preferred embodiment. This has a central foam body 3 with ribs 5, the trapezoidal cross section of which tapers towards the top layer 2. In the complementarily shaped space, a spiral spring 4 is used, the uppermost end of the winding 13 rests on the end face 11 of the profile elevation 5. These spiral springs 4 are preferably preloaded such that they act against the spring force of the foam body ribs 5. It is thereby achieved that the springing behavior inherent in the spring elements is dampened by the elasticity of the foam. The hardness of the springs can be chosen according to requirements and is essentially determined by the thickness of the spring wire. In the preferred embodiments, springs with a wire thickness of 1.4 to 2.6 mm are used. The maximum diameter of these springs is 60mm, but can of course be adapted to the geometry of the foam body. Plastic foams of 20-70 kg / m ³ are preferably used as the foam body. The profiled foam body 3 has, for example, a total height of 10 cm, the central web 8 of which has a thickness of 15 mm. The height of the individual springs 4 is adapted to this overall height of the foam body and varies in the preferred embodiments between 6 cm and 14 cm. The adhesive layer 12 creates a connection between the end faces 11 of the elevations 5 and the cover layer 2, such that the winding end 13 is held in place. In a simple embodiment, these cover layers 2 consist of foam with a thickness of approximately 25 mm, so that the entire innerspring can be reduced to a height of 11cm. The shape of the spring elements 4, which is adapted to the shape of the interspaces, prevents the spring elements 4 from rubbing against and damaging the foam body 3. A significant advantage in the combination of foam with metallic springs is the fact that the elasticity of the plastic foam, which usually diminishes in the longer term, can be maintained through the dimensional stability of the spiral springs.

Due to the independent positioning of the metallic springs, such a spring core also proves to be easy to assemble, i.e. can be cut around the springs in any way. Due to the double-conical shape of the spiral springs and the thin foam layer of the foam body in the middle area of the spring elements, their turns cannot come to rest on each other under extreme loads.

It goes without saying that differently shaped spring elements can be selected and used in accordance with the application. For example, biconical, cylindrical or barrel-shaped spring elements can be used. It is also in the technical ability to combine individual springs into groups in order to adapt the spring-elastic properties to the desired load profiles. It goes without saying that the person skilled in the art would also consider rubber springs or similar elastic elements instead of the spiral springs. Likewise, the foam body can be cut from one piece or constructed from several different layers. The recesses of the ribbed foam body can be slotted in a suitable manner for easier assembly of the spring elements. The flanks of the individual ribs can be adapted to the shape of the spring. It is also within the skill in the art to choose an adhesive with the desired elasticity for the adhesive layer 12.

Claims (10)

Spring core for an upholstery made of a central foam body provided with cover layers with a plurality of spring elements which are inserted in the foam body, characterized in that the central foam body (3) is provided on both sides with a profile, the elevations (5) and depressions (7) have a complementary geometric shape, the spring elements (4) being arranged in the recesses (7) of the profile. Spring core according to claim 1, characterized in that the foam body (3) has ribs (5, 8) running parallel to one another on both sides. Spring core according to claim 2, characterized in that the elevations (5) have a trapezoidal cross section. Spring core according to claim 2, characterized in that the elevations (5) have a rectangular cross section. Spring core according to one of claims 1 to 4, characterized in that the spring elements (4) are metallic spiral springs. Spring core according to claim 5, characterized in that the ends of the individual spiral springs (4) rest on the elevations (5) of the profile. Spring core according to claim 6, characterized in that the cover layers (2) are glued to the end faces (11) of the elevations (9) and thereby the ends of the individual spiral springs (4) are glued between these elevations (9) and the cover layers (2) are. Spring core according to one of claims 1 to 7, characterized in that the spring elements (4) have a biconical shape. Spring core according to one of claims 1 to 7, characterized in that the ends of the spring elements (4) have a diameter of 60mm. Upholstery element with a spring core according to claim 1.

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