EP0139956B1 - Spring core for a mattress - Google Patents

Abstract

The spring core for a mattress consists of several, identically formed spring coils arranged in side by side rows with each row forming a wire piece having an upper and a lower mutually aligned end spiral in a U-shape, and having opposite legs joined together by a base webb. Adjacent coil springs are joined together at their end spirals along abutting legs by helical connecting springs. To arrange the springs at tight angles in rows and columns, a length of one leg is greater than the length of another leg and all the coil springs are oriented in the same direction, except along a edge region of the spring core.

Description

The invention relates to a coil spring for the innerspring of a mattress according to the preamble of patent claim 1.

GB-A-386 251 already discloses such a coil spring for the spring core of a mattress. The longer legs of the known coil spring each have a bend at the end in the manner of a hook bent in the plane of the end windings in order to be able to fix the ends of the coil spring in the region of a helical connecting spring. The disadvantage here is that the respective ends of the coil spring are limited in flexibility under high loads and disadvantageously get caught in the coil spring, so that high loads on the spring core can lead to deformation of the respective end region of the coil spring and the connecting spring. Furthermore, the hooks bent in the plane of the respective end turn can easily damage a mattress lying on it. In addition, due to the hardened spring steel, the formation of a bent hook is complex during assembly and can easily lead to the spring steel breaking out.

The invention therefore has the task of developing a coil spring of the type mentioned in such a way that the assembly of the spring core is facilitated and high loads can be absorbed resiliently without fear of deformation of the coil spring or the connecting spring.

To achieve the object, the invention is characterized in that the slightly arcuate wire piece on the free longer legs is formed obliquely inwards out of the plane of the end turns and in connection with the kick end and that, with the exception of an edge region of the spring core, all coil springs are aligned equally.

The essence of the invention is that the respective end regions of the coil spring in the area of a connecting spring are not fixed relentlessly when they are arranged in the innerspring of a mattress, but rather that the ends of the coil spring are resilient in narrow areas due to the oblique, stepped design. Therefore, the ends of the coil spring can dodge slightly under high loads in the area of the helical connecting spring, as a result of which irreversible deformations are avoided. Damaging an overlying mattress is also avoided by the inclined inward bend out of the plane of the end turns. The installation of the spring core, in particular in connection with an automatic assembly, is facilitated by the only slight step-shaped inclined bending of the respective ends.

In an embodiment of the invention, it is provided that each end turn has five bending points, of which the first bending point defines the transition of the screw turn into the shorter leg; the second bending point the transition of the shorter leg into the base web; the third bending point is the transition of the base web into the longer leg; the fourth bending point the transition of the longer leg into the bent piece of wire; and the fifth bending point the transition of the piece of wire into the obliquely bent kink end. The proposed arrangement of the bending points achieves an excellent connection of the legs in the helical connecting spring encompassing them. Through this preferred embodiment of the respective end regions of the helical spring, loads occurring during the stringing together are advantageously continued, with the longer leg in each case being flexibly arranged in the region of the connecting spring within certain limits, in particular to avoid deformations. This also prevents harmful squeaking and scratching noises that could otherwise easily result if deformations occur.

All of the information and features disclosed in the documents, in particular the spatial design shown in the drawings, are claimed to be essential to the invention insofar as they are new to the prior art, individually or in combination.

The invention is explained in more detail below with the aid of drawings which illustrate only one embodiment. Further features and advantages of the invention which are essential to the invention emerge from the drawings and their description.

• Figur 1: perspektivische Seitenansicht einer Schraubenfeder nach der Erfindung,
• Figur 2: Draufsicht auf die Stirnseite der Schraubenfeder nach Figur 1,
• Figur 3: perspektivische Seitenansicht eines Teils eines Federkerns,
• Figur 4: Draufsicht auf die Eckpartie eines Federkerns nach Figur 3,
• Figur 5: Stirnansicht des Federkerns in Richtung des Pfeiles V in Figur 3 und 4.

Show it:

• FIG. 1: perspective side view of a coil spring according to the invention,
• FIG. 2: top view of the end face of the coil spring according to FIG. 1,
• FIG. 3: perspective side view of part of a spring core,
• FIG. 4: top view of the corner part of a spring core according to FIG. 3,
• Figure 5: Front view of the spring core in the direction of arrow V in Figures 3 and 4.

The coil spring 10 shown in FIG. 1 preferably has two successive screw turns 15, 16, the upper screw turn 15 in the upper level 1 of the spring core ending in a U-shaped curved end turn 11, while the lower screw turn 16 in the lower level 2 of the Spring core runs into a lower end turn 31. Both end turns 11, 31 are the same, so that the description of one end turn enough. The end windings 11, 31 lie one above the other in alignment with the spring axis 17. The active length of the wire, which determines the spring property of the helical spring 10, extends from the position 23 of the upper end turn 11 down to the position 24 of the lower end turn 31. This means that parts of the end turns 11, 31 also take part in the spring work, in particular the base web 18 and the adjoining, shorter leg 13 of the respective U-shaped end winding 11, 31. This explains the very favorable use of the wire, ie with relatively little wire, superior suspension properties are achieved.

To explain the shape of the respective U-shaped end windings 11, 31 reference is made to the illustration in Figure 1 and Figure 2. FIG. 2 shows the bottom view of the lower end turn 31 in solid lines, while the parts above it, in particular the upper end turn 11, are indicated in dashed lines. For the sake of clarity, the shorter leg 13 of the upper end turn 11 is not shown in FIG. 2.

It is important first of all that the U-shaped curved end turn is at a lateral distance from the screw turns 15, 16. This is represented by the distance 3 of the longer leg 12 of the end turn from the associated screw turn 16, while on the opposite side the shorter leg 13 has a smaller distance 4 from the screw turn 16 of the coil spring 10. These distances 3, 4 ensure that the end turns do not come into contact with the screw turns 15, 16 even when the coil spring 10 is subjected to extreme loads.

As described at the beginning, the respective end turn 11, 31 is bent in a U-shape. The end turn 31 shown in solid lines in FIG. 2 is formed from a shorter leg 13, the base web 18 forming the base of the U and the longer leg 12.

The shorter leg 13 of the U-shaped end turn 31 connects to the descending screw turn 16 of the coil spring 10 via a first bending point 5. The shorter leg 13 has a length 26. Via a second bending point 6, the shorter leg 13 runs into the base web 18, which at the time was slightly curved. At the opposite end of the base web 18, a third bending point 7 is arranged, to which one end of the longer leg 12 connects. This, in turn, runs slightly curved with a length 25 to the fourth bending point 8. There, again slightly curved and bent out of level 1, the mattress, a piece of wire 28 attaches to the front free end of which via a fifth bending point 9 the kink 14 starts.

The meaning of the bent wire piece 28 with the bent end 14 attached to it can be seen from FIG. 5. There it can be seen that the wire pieces 28 with the kink ends 14 attached to them are each bent obliquely inwards in the direction of the spring axis 17, so that there is no contact with the helical coils 15, 16 of the coil springs 10, 10 ', and no excavation of the padding is to be feared. The respective wire end of the open end turn 11, 31 is thus optimally protected. The upper end turn 11 is formed analogously to the lower end turn 31, as can be seen from the broken line in FIG. 2. It is essential here that the two longer legs 12 and the two shorter legs 13 of the two superimposed and aligned end windings 11, 13 lie exactly mirror-symmetrically with respect to one another along a longitudinal center line through the spring axis 17. As a result, a symmetrical loading of the coil spring 10 is achieved.

Figures 3 to 5 show a partially assembled spring core. FIGS. 3 and 4 also show the edge region 27 of the spring core, where it can be seen that only in this edge region 27 are the coil springs 10, which are otherwise oriented the same way, so that the otherwise lower end turn 31 lies there at the top. This ensures that the base web 18 always forms the outer edge of the spring core and thus it is possible to connect a peripheral circumferential wire 32 in the upper and lower level 1, the spring core on the edge side to the end windings of the associated coil springs and with the peripheral peripheral connecting spring 33 with them To fasten coil springs.

FIGS. 3 and 4 show the coil springs 10 arranged in rows and columns. The connecting lines 19 through the spring axes 17 form vertical lines in the drawing plane of FIG. 4, while horizontal lines are defined in an analogous manner through the connecting lines 19a. The connecting lines 19, 19a intersect at right angles, so that the edge sides of the spring core assembled in this way also form right angles. The formation of said right angles does not lead to the offset previously described in connection with DE-OS-3 321 991, which could only be eliminated by corresponding corrections on the assembly machine.

The right angles are obtained as shown in FIG. 4 in that, in the helical connecting spring, both the longer leg 12 of one helical spring and the shorter leg 13 of the adjacent helical spring emerge on one spring turn 20, while on the opposite side after the passage of four spring coils the shorter leg 13 of a coil spring exits the spring turn 21, while the longer leg 12 of the adjacent coil spring exits a spring turn later, namely on the spring turn 22.

It also follows from FIG. 3 and FIG. 4 that, due to the kinks 5, 6 in the region of the shorter legs 13, this leg 13 is excellently fixed in the region of the connecting spring 30. In an analogous manner, the longer leg 12 is also fixed in the connection spring 30 in the region of the bends 7, 8.

In the edge region 27, the coil springs are turned over so that the end turn 31, which is otherwise at the bottom, is at the top.

In Figure 5, two adjacent, adjacent coil springs are shown. So that it can be seen which part belongs to which helical spring, all reference numerals of the helical spring shown in FIG. 5 are provided with a prime. The same designations are also contained in FIG. 4 Hnks below, so that it can be seen where the two coil springs 10, 10 'shown in FIG. 5 are arranged in the spring core.

It is clear from the illustration in FIG. 5 that in the area of the connecting springs 30, which each receive a longer leg 12 of one helical spring 10 and a shorter leg 13 'of the adjacent helical spring 10', these two legs 12, 13 'one above the other in a clear cross section the connecting spring 30 are arranged. As a result, these legs 12, 13 'are optimally secured against displacement, which ensures that no undesirable scratching or squeaking noises can occur.

It is also clear from the illustration that the bent wire pieces 28 with the bending ends 14 attached to them are each bent inwards in the direction of the spring axis 17, 17 '. They are each bent out of level 1, 2 of the innerspring, so that an undesired contact with the cushioning material is excluded in any case.

It is also clear from FIG. 5 that the base webs 18, 18 'of mutually adjacent coil springs 10, 10' overlap, so to speak, in the manner of a roof tile, which leads to the said tight fit of the legs 12, 13 'and 12', 13 in the connecting springs 30. In order to achieve said overlap, it is necessary that the longitudinal axes of the base webs 18, 18 'are inclined at an angle 29 to the horizontal, as can be seen in FIG. 5.

• 1 obere Ebene (Endwindung 11)
• 2 untere Ebene (Endwindung 31)
• 3 Abstand
• 4 Abstand
• 5 erste Biegestelle
• 6 zweite Biegestelle
• 7 dritte Biegestelle
• 8 vierte Biegestelle
• 9 fünfte Biegestelle
• 10 Schraubenfeder
• 11 Endwindung, obere
• 12 langer Schenkel
• 13 kurzer Schenkel
• 14 Knickende
• 15 Schraubenwindung
• 16 Schraubenwindung
• 17 Federachse
• 18 Basissteg
• 19 Verbindungslinie 19a
• 20 Federwindung
• 21 Federwindung
• 22 Federwindung
• 23 Position
• 24 Position
• 25 Länge (Schenkel 12)
• 26 Länge (Schenkel 13)
• 27 Randbereich
• 28 Drahtstück
• 29 Winkel
• 30 Verbindungsfeder
• 31 untere Endwindung
• 32 Umfassungsdraht
• 33 Verbindungsfeder, randseitig

The described arrangement of all helical springs in the same direction, with the exception of the helical springs turned over in the edge region 27, and by the unequal length of adjacent legs 12, 13, the advantage of a surprisingly quick and easy assembly is achieved without special measures having to be taken to the described offset to avoid.

• 1 upper level (end turn 11)
• 2 lower level (end turn 31)
• 3 distance
• 4 distance
• 5 first bending point
• 6 second bending point
• 7 third bending point
• 8 fourth bending point
• 9 fifth bending point
• 10 coil spring
• 11 final turn, upper
• 12 long legs
• 13 short legs
• 14 kinking
• 15 screw turn
• 16 screw turn
• 17 spring axle
• 18 base bridge
• 19 connecting line 19a
• 20 spring turn
• 21 spring turn
• 22 spring turn
• 23 position
• 24 position
• 25 length (leg 12)
• 26 length (leg 13)
• 27 edge area
• 28 piece of wire
• 29 angles
• 30 connecting spring
• 31 lower end turn
• 32 perimeter wire
• 33 Connection spring, on the edge

Claims (2)

1. Coil spring for the spring core of a mattress, the coil spring having end windings (11, 31) formed in a U-shape each with a lightly arcuate wire element (28) at the free end and the mutually opposed branches (12, 13) of each end winding (11, 31) being connected together via a base piece (18), the free branch (12) being made longer than the other branch (13) and one long branch (12) and one short branch (13) each being interconnected in the spring core by means of coil-shaped connecting springs, characterised in that the lightly arcuate wire element on each of the longer free branches is formed to extend obliquely inwards out of the plane (1, 2) of the end windings (11, 31) and with a step-like connection to the angled end (14) and that all the coil springs are identically aligned except for a marginal portion (27) of the spring core.

2. Coil spring according to claim 1, characterised in that each end winding (11, 31) has five bending points (5 - 9) of which the first bending point (5) defines the transition of the coil winding (15,16) into the shorter branch (13); the second bending point (6) defines the transition of the shorter branch (13) into the base piece (18); the third bending point (7) defines the transition of the base piece (18) into the longer branch (12); the fourth bending point (8) defines the transition of the longer branch (12) into the bent-over wire element (28); and the fifth bending point (9) defines the transition of the wire element (28) into the obliquely bent over angled end (14).

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