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Title:
A BABY CARRIER
Document Type and Number:
WIPO Patent Application WO/2016/153411
Kind Code:
A1
Abstract:
The invention relates to a baby carrier comprising a harness (2) and a harness-carried front piece (6) which forms at least a part of a baby-carrying pouch. The front piece (6) comprises a material having little or no inherent stability and is provide with at least one longitudinal flexible stiffening element (20;30;40) which is attached to and extends over a major portion of the front piece (6) in a longitudinal direction thereof.

Inventors:
ELMBERG LISEN (SE)
WIKNER JAKOB (SE)
ANDRÉN MÅRTEN (SE)
VEJBRINK ULRIKA (SE)
RAMEL-WÅHRBERG ELISABETH (SE)
Application Number:
PCT/SE2016/050211
Publication Date:
September 29, 2016
Filing Date:
March 16, 2016
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
BABYBJÖRN AB (SE)
International Classes:
A47D13/02; A47D13/08
Domestic Patent References:
WO2011071441A12011-06-16
Foreign References:
US20120187162A12012-07-26
US20120187161A12012-07-26
Attorney, Agent or Firm:
EHRNER & DELMAR PATENTBYRÅ AB (SE)
Download PDF:
Claims:
C L A I M S

1. A baby carrier comprising a harness (2) and a harness- carried front piece ( 6 ; 106 : 206 ; 306 ; 406 ; 506 ) which forms at least a part of a baby carrying pouch, characterized in that the front piece ( 6 ; 106 : 206 ; 306 ; 406 ; 506 ) comprises a material having little or no inherent stability and is provided with at least one longitudinal flexible

stiffening element (20;30;40) which is attached to and extend over a major portion of the front piece

( 6 ; 106 : 206 ; 306 ; 406 ; 506 ) in a longitudinal direction thereof so as to increase the stability of the front piece ( 6 ; 106 : 206 ; 306 ; 406 ; 506 ) and thereby enabling a wearer of the baby carrier to, by himself/herself , place a baby into the baby carrying pouch of the baby carrier when carried by the wearer without the necessity to use one hand for opening/widening the baby carrying pouch.

2. The baby carrier according to claim 1, characterized in that said material is a material selected from the group consisting of a mesh fabric, net-like layers of material, single layer fabric, knitted fabric, woven fabric, felt, leather, foamed plastic with an open-cell structure and foamed plastic with a closed-cell structure.

3. The baby carrier according to claim 1 or 2, characterized in that said material is a 3D mesh fabric.

4. The baby carrier according to any one of claims 1 to 3, characterized in that said at least one longitudinal flexible stiffening element (20;30;40) is arranged on either an external side, or on an internal side of said front piece ( 6 ; 106 ; 206 ; 306 ; 406 ; 506 ) or within the material forming said front piece ( 6 ; 106 ; 206 ; 306 ; 406 ;

506), or a combination thereof.

The baby carrier according to any one of claims 1 to 3, characterized in that two longitudinal flexible

stiffening elements (20;30;40) are arranged on either an external side, or on an internal side, or within the material forming said front piece ( 6 ; 106 ; 306 ; 406 ) , or a combination thereof, and placed on each side of a centre axis of the front piece ( 6 ; 106 ; 306 ; 406 ) .

The baby carrier according to claim 5, characterized in that the two longitudinal flexible stiffening elements (20;30;40) are at their upper ends connected to one another .

The baby carrier according claim 5 or 6, characterized in that, in case said front piece ( 6 ; 106 ; 206 ; 306 ; 406 ; 506 ) is provided with two longitudinal flexible stiffening elements ( 20 ; 30 ; 40 ) , wherein each longitudinal flexible stiffening element has a degree of flexural resistance so that a longitudinal flexible stiffening element

(20;30;40) which is fixed at a first end portion (50) and protrudes horizontally 150 mm from said first end portion to a free end (51) requires a load of 10 to 60 grams, preferably 15 to 40 grams, and most preferably about 20 grams, at said free end (51) for the free end to bend down 75 mm.

The baby carrier according to any one claims 5 to 7, characterized in that said two longitudinal flexible stiffening elements (20;30;40) are laterally separated from each other by a distance L of 0 to 220 mm, preferably by 10 to 150 mm, and most preferably by 40 to 80 mm measured from a centre line of one longitudinal flexible stiffening element to a centre line of the other longitudinal flexible stiffening element (20;30;40) .

9. The baby carrier according to any one of claims 1 to 8, characterized in that the baby carrier further comprises a waist belt (11), to an upper edge (14) of which is attached a lower edge (15) of the front piece (6), and that said at least one longitudinal flexible stiffening element (20; 30; 40) extends from a middle portion of the waist belt (11) to about an upper boarder edge

(12; 112; 212; 312; 412; 512) of said front piece

(6; 106:206; 306; 406; 506) .

10. The baby carrier according to any one of claims 1 to 8, characterized in that said at least one longitudinal flexible stiffening element (20;30;40) extends from a lower portion ( 360 ; 460 ; 560 ) of said front piece

(306; 406; 506) to about an upper boarder edge

(312; 412; 512) of said front piece (306 ; 406 ; 506 ) .

11. The baby carrier according to any one of claims 1 to 10, characterized in that said at least one longitudinal flexible stiffening element (20) comprises flexible stiff filaments (21), preferably 3 to 12 flexible stiff

filaments, most preferably 5 to 10 flexible stiff

filaments, and particularly 8 flexible stiff filaments. 12. The baby carrier according to any one of claims 1 to 10, characterized in that said at least one longitudinal flexible stiffening element (30) is formed as a solid elongated one-piece material (30), and that said at least one longitudinal flexible stiffening element (30) is provided along its longitudinal side edges (31) with a recess (32), said recess (32) forming a weakening in said at least one longitudinal flexible stiffening element (30) enabling the same to be sewed onto the front piece

(6,-106:206,-306,-406,-506) .

13. The baby carrier according to any one of claims 1 to 10, characterized in that said at least one longitudinal flexible stiffening element (40) is formed as a solid elongated one piece material (40), and that said at least one longitudinal flexible stiffening element (40) is provided along its longitudinal direction with a centre recess (132), said recess (132) forming a weakening in said at least one longitudinal flexible stiffening element (40) enabling the same to be sewed onto the front piece ( 6 ; 106 : 206 ; 306 ; 406 ; 506 ) .

14. The baby carrier according to any one of claims 1 to 13, characterized in that said at least one longitudinal flexible stiffening element (20;30;40) has the shape of a band, strip or rod, and that it has a fixed stiffness.

Description:
A BABY CARRIER

Field of the invention

The present invention relates to a baby carrier of the kind defined in the preamble of the accompanying claim 1. Background of the invention

A certain type of known baby carriers comprises a harness having at least chest straps arranged to extend around both shoulder regions of the wearer and a front piece which is carried by the harness and which forms a baby carrying pouch or at least a part of said baby carrying pouch. At least the upper lateral corner portions of the front piece are

preferably detachably connected to corresponding nearby connecting points of the harness. Also other part/parts of the front piece may be detachably connected to corresponding nearby connecting points of the harness. The front peace is flexible and therefore shapes itself to at least some extent by lifting and folding under the influence of the weight of the baby carried in the pouch. Moreover, the front piece is essentially comprised of a low-stretchable or non-stretchable material, so as to provide comfortable and ergonomical support for the baby carried.

In the past the front piece has preferably been made of a padded material, i.e. two sheets of fabric with an interlayer of a suitable padding material, so as to give the front piece stability/rigidity, and thereby facilitate positioning of the baby into the baby carrier when carried by the wearer, and also comfort to the baby carried.

However, such a padded front piece will to some extent form an isolating barrier and thereby be quite warm for the baby, particularly during summer time, or when the baby is carried indoors .

Therefore, instead of a padded front piece, baby carriers have been developed having at least a front piece made of an airy material such as a mesh fabric, for instance. A mesh fabric is a fabric having open voids and will thus be very airy. The front piece can also be made of a single layer fabric or any other light and/or suitable material, such as a knitted or woven fabric. Common for all these materials/fabrics are that they have no or little inherent rigidity/stability, i.e. they are

shapeless, and therefore the front piece and the baby carrier as such, since it consists to a major portion of the front piece, shows no or little rigidity/stability. This makes it difficult to place a baby into the baby carrying pouch when the baby carrier is carried by the wearer, since the opening of said carrying pouch formed between the wearer and the front piece will at least partly collapse. This will be particularly noticeably when one or both of the upper lateral corner portion (s) of the front piece is (are) detached from the corresponding nearby connecting points of the harness.

Accordingly, an object of the present invention is to provide a baby carrier, the front piece of which shows the necessary rigidity/stability to enable a wearer of the baby carrier to, by himself/herself , place a baby into the baby carrying pouch of the baby carrier when carried by the wearer without the necessity to use one hand for opening/widening the baby carrying pouch.

According to the invention, this object is achieved by a baby carrier comprising a harness and a harness-carried front piece which forms at least a part of a baby carrying pouch,

characterized in that the front piece comprises a material having little or no inherent stability and is provided with at least one longitudinal flexible stiffening element which is attached to and extend over a major portion of the front piece in a longitudinal direction thereof so as to increase the stability of the front piece and thereby enabling a wearer of the baby carrier to, by himself/herself , place a baby into the baby carrying pouch of the baby carrier when carried by the wearer without the necessity to use one hand for

opening/widening the baby carrying pouch.

Other embodiments of the invention will be apparent from the accompanying dependent claims.

Brief description of drawings

The invention will now be described by way of non-limiting examples with reference to the accompanying drawing, in which

- Fig. 1 is a front view of the inventive baby carrier with a front piece according to a first embodiment having two

laterally separated stiffening element located on the external side of said front piece,

- Fig. 2 is a view partly from the side of the baby carrier in Fig. 1,

- Fig. 3 is a front view of the inventive baby carrier with a front piece according to a second embodiment having two laterally separated stiffening element located on the external side of said front piece, the upper ends of said stiffening elements being connected to one another,

- Fig. 4 is a front view of the inventive baby carrier with a front piece according to a third embodiment having one central stiffening element located on the external side of the front piece,

- Fig. 5 is a front view of only the front piece according to a fourth embodiment of the inventive baby carrier having two laterally separated stiffening elements located on the

external side of said front piece,

- Fig. 6 is a front view of only the front piece according to a fifth embodiment of the inventive baby carrier having two laterally separated stiffening elements located on the

external side of said front piece, the upper ends of said stiffening elements being connected to one another,

- Fig. 7 is a front view of only the front piece according to a sixth embodiment of the inventive baby carrier having one central stiffening element located on the external side said front piece,

- Fig. 8 is a sectional view from above take along line A-A in Fig. 1 and 3 showing the two stiffening elements placed on the external side of said front piece,

- Fig. 9 shows the same view as in Fig. 8 but with the two stiffening elements placed on the internal side of said front piece,

- Fig. 10 is a sectional view from above take along line B-B in Fig. 4 showing the one stiffening element placed on the external side of the front piece,

- Fig. 11 shows the same view as in Fig. 10 but with the one stiffening element placed on the internal side of the front piece,

- Fig. 12 shows the same view as in Fig. 10 but with the one stiffening element placed in the middle of the material/fabric of the front piece,

- Fig. 13 shows the same view as in Fig. 8 but with the two stiffening elements placed in the middle of the

material/fabric of the front piece,

- Fig. 14 is a sectional view of a first embodiment of a stiffening element used for stiffening the front piece of the inventive baby carrier,

- Fig. 15 is a sectional view of a second embodiment of the stiffening element used for stiffening the front piece of the inventive baby carrier,

- Fig. 16 is a sectional view of a third embodiment of the stiffening element used for stiffening the front piece of the inventive baby carrier, and

- Fig. 17 shows a flexural resistance test performed on a stiffening element.

Description of preferred embodiments

In the description and claims below expressions such as upper, lower, external side, internal side etc. are to be understood in connection with the normal use of the baby carrier as carried by a wearer.

Figs. 1 and 2 show a first embodiment of a baby carrier 1 according to the invention comprising a harness 2 having adjustable chest straps 3, which are arranged to extend around the both shoulder regions of the wearer and which on the backside of the wearer are preferably connected to each other by a fitting 4 which is adjustable along the length of the chest straps 3. A baby-carrying pouch 5 is formed between at least the chest straps 3 and a front piece 6 carried by the harness 2. A leg opening is formed at each side and at a lower end of the front piece. The front piece 6 is at an upper edge region 8 detachably connected to respective chest strap 3 by a detachable connecting device 9, whereby the upper edge region 8 can be folded downwardly. A baby carrier having a front piece of the above-mentioned type is disclosed in Applicant's US patent No. 8,627,988, for instance, which is hereby incorporated by reference.

In the embodiment shown in Figs. 1 and 2 the baby carrier 1 is provided with an adjustable waist belt 11, and a lower portion 15 of the front piece 6 is connected to said waist belt 11, preferably at an upper edge 14 thereof, and forms a seat support (not shown) . A first end 3a of respective chest strap 3 is attached to the waist belt 11, while a second end 3b preferably is detachably connected by a detachable connecting device 7 to at least one edge portion/back portion of the front piece 6 situated in the vertical direction, as seen when the baby carrier is worn, somewhat below the centre of the height of the front piece. More particularly, the upper edge region 8 of the front piece 6 is connected to the first end 3a of respective chest strap 3 via an adjustable strap 10, at a first end 10a of which one part of the detachable connecting device 7 is attached, and a second end 10b of which is attached to the upper edge region 8 of the front piece 6. Preferably, the upper edge region 8 is a padded region having some rigidity/stability so as to form a suitable head rest.

Regarding the expression that the chest straps 3 are arranged to extend around both shoulder regions of the wearer it is to be understood that the chest straps either can be crossed or may stretch parallel to each other on the back side of the wearer, whereby in both cases the chest straps are connected to each other by a fitting, such as fitting 4 or any other suitable arrangement, which is movable along the length of the straps. The front piece 6 of the inventive baby carrier is preferably made of a material having no or low inherent rigidity/

stability such as a mesh fabric, net-like layers of material, single layer fabric, knitted fabric, woven fabric, felt, leather, foamed plastic with an open-cell structure or foamed plastic with a closed-cell structure or any other suitable material/fabric. In a preferred embodiment the front piece 6 is made of a 3D mesh fabric.

To increase the rigidity/stability of the front piece 6 at least one, preferably two, longitudinal flexible stiffening elements 20; 30; 40 are adapted to extend from the upper edge region 8 of the front piece 6, preferably from about the middle of the height of said upper edge region 8, to at least the connection between the front piece 6 and the waist belt 11, preferably to about the middle of the height of said waist belt, as seen by broken lines of the left stiffening element in Fig. 1. The ends of the stiffening elements 20;30;40 are preferably arranged inside of/hidden by the fabric/material forming part of the upper edge region 8 and the waist belt 11, respectively.

The stiffening element 20;30;40 has the function of a batten, i.e. to increase the rigidity/stability of the front piece 6 and extends over the front piece 6 in a longitudinal direction thereof . In the embodiment shown in Figs. 1 and 2, two laterally substantially parallel longitudinal flexible, possibly non- stretchable, stiffening elements 20;30;40 are provided on the external side of said front piece 6 and on each side of a centre axis of the front piece 6, preferably symmetrically arranged relatively to the centre axis of the front piece 6. The front piece 6 may be provided with a folding line 13 extending between a lower portion of the second end 10b of each adjustable strap 10, which second end 10b is attached to the upper edge region 8. This fold line 13 makes it easier to fold down the upper edge region 8.

Fig. 3 shows a second embodiment of a baby carrier 100 according to the invention which is formed in the same way as the baby carrier shown in Figs. 1 and 2 with the exception of that the two laterally separated stiffening elements 20;30;40 formed on the external side of a front piece 106 are at their upper ends connected to one another so as to form an

essentially U-shaped stiffening element turned upside-down which extends up to about an upper boarder edge 112 of the front piece 106. The U-shaped portion is preferably arranged inside of/hidden by the fabric/material forming an upper edge region 108.

Since the other features of the baby carrier 100 are the same as of the baby carrier 1 according to the first embodiment they will not be described in further detail. Fig. 4 shows a third embodiment of a baby carrier 200

according to the invention, which baby carrier is formed in the same way as the baby carrier 6; 106 according to the first and second embodiments with the exception of that only one longitudinal flexible stiffening element 20;30;40 is provided on the external side of a front piece 206. An uppermost portion 201 of the stiffening element 20;30;40 has preferably a progressively increasing width towards an upper boarder edge 212 of an upper edge region 208 so as to increase the area made stiffer by said stiffening element 20;30;40 and thereby better supporting a child's head. Preferably, this uppermost portion 201 of the stiffening element 20;30;40 is arranged inside of/hidden by the fabric/material forming the upper edge region 208, as seen by broken lines.

In Figs. 5 to 7 fourth to sixth embodiments of another type of front piece 306 ; 406 ; 506 are shown and mounted to a harness, which front piece is of a type essentially provided at a baby carrier as disclosed in Applicant's US patent Nos. 8,752,739 or 7,284,503, for instance, which are hereby incorporated by reference. Therefore, the front piece and the harness to which the front piece 306 ; 406 ; 506 is mounted will only be described regarding the features which are different from the features of the baby carriers disclosed in the first to third

embodiments above.

As can be inferred from Fig. 5, in the fourth embodiment, the external side of a front piece 306 is provided with two longitudinal flexible essentially parallel stiffening elements 20; 30; 40 of the same type as provided on the front piece 6 of the first embodiment, and on each side of a centre axis of the front piece 306.

The front piece 306 is further provided with an upper edge region 308, and each of the two stiffening elements 20;30;40 are arranged to extent to an upper boarder edge 312 of the upper edge region 308. The front piece 306 is at the upper edge region 308 detachably connected to respective chest strap of a harness (not shown) by a detachable connecting device 309 provided at an end of a strap 310, whereby the upper edge region 308 can be folded downwardly, preferably at a folding line 313 extending between a lower portion of an attachment point 311 for respective strap 310 to the upper edge region 308. The width of the upper edge region 308 can be reduced by an adjustable strap 311 provided at each side of the upper edge region 308. As seen in Fig. 5 a lower portion 360 of said front piece 306 is not provided with said stiffening elements 20;30;40, since said lower portion 360 forms a tongue which is adjustably attached to the harness by a connecting device (not shown) and forms a seat support (not shown) for the child carried.

However, the stiffening elements 20;30;40 extend over a major portion of the front piece 306 in a longitudinal direction thereof .

Fig. 6 shows a fifth embodiment of a front piece 406 of the same type as shown in Fig. 5. The only difference between the front piece 406 and the front piece 306 is that the two laterally separated stiffening elements 20;30;40, in the same way as in the second embodiment shown in Fig. 3, are at their upper ends connected to one another so as to form an

essentially U-shaped stiffening element turned upside-down extending up to about an upper boarder edge 412. A lower portion 460 of said front piece 406 is not provided with said stiffening elements 20;30;40 of the same reasons as for the fourth embodiment. Fig. 7 shows a sixth embodiment of a front piece 506 of the same type as shown in Figs. 5 and 6. The only difference between the front piece 506 and the front piece 306 and 406, respectively, is that only one longitudinal flexible

stiffening element 20;30;40 is provided on the external side of a front piece 506. An uppermost portion 501 of the

stiffening element 20;30;40 has preferably a progressively increasing width towards an upper boarder edge 512 of an upper edge region 508 so as to increase the area made stiffer by said stiffening element 20;30;40 and thereby better supporting a child's head. In said embodiment the stiffening element

20; 30; 40 is visible all the way up to the upper boarder edge 512 of the upper edge region 508. A lower portion 560 of said front piece 506 is not provided with said stiffening element 20; 30; 40 of the same reasons as for the fifth embodiment.

Fig. 8 is a view from above taken along line A-A in Fig. 1 and 3 showing two stiffening elements 20;30;40 arranged on the external side of the front piece 6 ; 106 ; 306 ; 406.

Fig. 9 is a view corresponding to the one shown in Fig. 8 but showing two stiffening elements 20;30;40 arranged on an internal side of said front piece 6 ; 106 ; 306 ; 406. Fig. 10 is a view from above taken along line B-B in Fig. 4 showing one stiffening element 20; 30; 40 arranged on the external side of the front piece 206;506.

Fig. 11 is a view corresponding to the one shown in Fig. 10 but showing one stiffening element 20; 30; 40 arranged on the internal side of said front piece 206;506.

Fig. 12 is a view from above taken along line B-B in Fig. 4 showing one stiffening element 20;30;40 arranged within the fabric/material of the front piece 206;506.

Fig. 13 is a view from above taken along line A-A in Figs. 1 and 3 showing two stiffening elements 20;30;40 arranged within the fabric/material of the front piece 6 ; 106 ; 306 ; 406.

Fig. 14 shows a sectional view of a first preferred embodiment of the longitudinal flexible stiffening element 20 used for stiffening the front piece 6 ; 106 ; 206 ; 306 ; 406 ; 506 of the inventive baby carrier.

In said first embodiment of the stiffening element 20 it is formed of several elongated round solid flexible stiff filaments 21 which are preferably interwoven into a suitable fabric 22 and made of a plastic material, preferably

polyamide, so as to form a band shaped stiffening element. The stiffening element (s) 20 can be sewed onto the front piece 6 ; 106 ; 206 ; 306 ; 406 ; 506. In Fig. 15 a second embodiment of the longitudinal flexible stiffening element 30 is shown. In said second embodiment the stiffening element 30 is formed as a solid elongated one-piece material, preferably in the form of a "ruler", and provided along its longitudinal side edges 31 with a recess 32. Said recess 32 forms a weakening enabling the stiffening element (s) 30 to be sewed onto or in any other suitable way to be

attached to the front piece 6 ; 106 ; 206 ; 306 ; 406 ; 506. The

longitudinal flexible stiffening element (s) 30 may be provided with holes (not shown) so as to increase the airiness of the same.

In Fig. 16 a third embodiment of the longitudinal flexible stiffening element 40 is shown. The stiffening element 40 corresponds to the stiffening element 30, but is provided in its longitudinal direction and at the centre with only one recess 132 which forms a weakening enabling the stiffening element (s) 40 to be sewed onto or in any other suitable way to be attached to the front piece 6 ; 106 ; 206 ; 306 ; 406 ; 506. The longitudinal flexible stiffening element (s) 40 may be provided with holes (not shown) so as to increase the airiness of the same.

In case the front piece 6 ; 106 ; 206 ; 306 ; 406 ; 506 is formed of two mutually parallel and preferably net-like layers of material, such as mesh material, the stiffening element (s) 20;30;40 may be placed between these layers and fastened to the front piece by sewing. The stiffening element 20; 30; 40 shown has the shape of a strip, but it is obvious for the man skilled in the art that the stiffening element 20;30;40 can have any other suitable shape such as the shape of a rod. The degree of stiffness of the stiffening element 20;30;40 is measured as follows.

In case said front piece 6 ; 106 ; 306 ; 406 is provided with two longitudinal flexible stiffening elements 20;30;40, each longitudinal flexible stiffening element has a degree of flexural resistance so that a longitudinal flexible stiffening element 20;30;40 which is fixed at a first end portion 50 and protrudes horizontally 150 mm from said first end potion 50 to a free end 51 requires a load of 10 to 60 grams, preferably 15 to 40 grams, and most preferably about 20 grams, at said free end 51 for the free end to bend down 75 mm. See Fig. 17.

In the preferred embodiment of the stiffening element 20, shown in Fig. 14, the diameter of the filaments is 0.5 to 1 mm, preferably 0.6 to 0.9 mm, and most preferably about 0.75 mm, and the number of the filaments are 3 to 12, preferably 5 to 10, and most preferably 8, in each stiffening element 20.

However, it should be noted that, in the embodiments showing the front piece 206; 506 provided with one stiffening element 20;30;40, the stiffness of said one stiffening element

20;30;40 should be at least twice the stiffness of the two stiffening elements 20;30;40 combined.

In the same way, if the front piece is provided with more than two stiffening elements said elements all together should have at least the same stiffness as of the two stiffening elements 20; 30; 40 combined. When two longitudinal flexible stiffening elements 20;30;40 are provided they are laterally separated from each other by a distance L of 0 to 220 mm, preferably by 10 to 150 mm, and most preferably by 40 to 80 mm measured from a centre line of one longitudinal flexible stiffening element to a centre line of the other longitudinal flexible stiffening element.

Although, it is described above that the longitudinal flexible stiffening element (s) 20;30;40 is (are) provided on the

external side, on the internal side or within the

fabric/material of the front piece, it is to be understand that the stiffening element (s) can be arranged at the same time both on the external side and on the internal side, or on the external side and within the fabric/material, or on the internal side and within the fabric/material of the front piece, or any suitable combination thereof.

Furthermore, in the embodiments described above either one or two stiffening elements are provided at the front piece, but it is obvious for the man skilled in the art that more than two stiffening elements can be arranged. Furthermore, in all the embodiments described above and shown in the drawings the front piece has a folding line, but it is obvious for the man skilled in the art that this is an option.