Abstract:
The invention provides for a seat shell for seat furniture, in particular chairs, comprising a shell top and a shell base, said shell top has a substantially closed surface. The surface of the shell top has a surface structure with a plurality of intersecting recesses which form ventilation channels.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation of International Application No. PCT/EP2012/059337, filed on May 21, 2012, which claims priority to German Patent Application No. 10 2011 076 196.9, filed on May 20, 2011, the contents of each of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a seat shell for seating furniture, especially chairs, with a shell top and a shell base side. 
       BACKGROUND 
       [0003]    Seat shells for seating furniture with a shell top and a shell base side are known from the prior art. For example, seat shells made from plastic material are known whose internal volume is designed as a hollow body. It is known to provide openings in the surface forming the seat surface which lead into the interior volume or in the cavity of the seat shell in order to achieve a certain ventilation effect and hence to reduce the perspiration of the user. 
         [0004]    Adequate ventilation of the seat surface is yet not achieved, especially not if all openings on the seat surface are covered by the seated person, since the openings only lead into the cavity of the seat shell, therefore preventing or at least impeding circulation of air or an air exchange. Another disadvantage is that the openings allow the arrival of any kind of dirt, but also of liquids into the cavity of the seat shell, which may also clog the apertures himself. A cleaning of the interior of the seat shell is not possible or possible only with great difficulties. This is particularly disadvantageous when the seat shell is to be used for seating furniture in the school system where high demands are placed on hygiene. 
         [0005]    The object of the present invention was therefore to provide a seat shell for seating furniture, in particular chairs, which avoids the disadvantages known from the prior art and which in particular do allow for an improved ventilation of the seat surface. 
       SUMMARY 
       [0006]    According to the invention, this problem is solved by a seat shell for seating furniture, especially for chairs, according to the independent claim. Advantageous embodiments of the invention emerge from the dependent claims. 
         [0007]    Accordingly, the invention provides a seat shell for seating furniture, especially chairs, comprising a shell top and a shell base side. The shell top has a substantially closed surface, whereby the surface of the shell top has a surface structure with recesses which form channels for the passage of air. 
         [0008]    Thus, in an advantageous manner a ventilation in the area of the shell top is ensured as a circulation of air from one end of the recession to the other end of the recession is maintained even when a person sits on the seat shell, because of the recessions, forming channels or ventilation grooves respectively. In addition, it is prevented that dirt can enter the interior of the shell, because openings in the shell top into the cavity of the seat shell can be avoided. The recessions are preferably designed or formed in such a way that the seated person does have no unpleasant sensation. Instead, the seated person generally does feel the haptic impression created by the rest of the surface structure of the shell top. 
         [0009]    It is especially preferred when the recesses in the seating area do have a width of between 5 mm and 20 mm. At this width, sufficient ventilation function can be provided while easy accessibility of the recesses is guaranteed for cleaning purposes. 
         [0010]    It has been found to be advantageous when the surface structure of the shell top comprises a plurality of intersecting recesses. The intersecting recessions can form a network structure. The recessions may intersect at an angle of about 60° but different at an angle other than 60°. It can also be the case that more than two elongated recesses intersect at one point. 
         [0011]    The non-recessed areas of the surface structure form the bearing surfaces of the shell top. The bearing surfaces together form the seat area, or that side facing the back of a person forming the backrest. The intersecting elongated recesses provide a further improved ventilation of the shell top. The transitions between the recesses and the seating surface or respectively that side, facing the back of a person and forming the backrest, are substantially rounded. 
         [0012]    It has been found particularly advantageous when at least one recession in the surface structure does extend up to an outer edge of the shell top. As a consequence, the ventilation function is maintained substantially independent from the seating position. 
         [0013]    The elongated recesses may have a substantially smooth surface, preferably with no edges and corners. Thus, cleaning of the elongated recesses is substantially simplified. 
         [0014]    The seat surface forming part of the shell top can be curved in the front region in the center in a saddle shape, wherein the curvature may extend beyond the front edge of the shell top. Thus, a common seating position among students, namely sitting very close to the front of the chair, is supported. 
         [0015]    The backrest forming part of the shell top may have a vertical spine recess in the central region. The spine recess may widen up to the upper part. In one embodiment of the invention, the spine recess in the lower region has a width between 30 mm and 100 mm and a width between 20 mm and 60 mm in the upper region. 
         [0016]    According to a further embodiment of the invention, the spinal recess may be tapered to the top. 
         [0017]    Thus, a more pleasant and ergonomic seating is made possible, whereby an adequate ventilation also at the backrest forming part of the shell top is ensured at the same time by the recesses in the shell top. 
         [0018]    The depth of the spine recession may correspond substantially to the depth of the recessions on the surface structure. Preferably the spine recess intersects at least some of the recessions of the surface structure, so that an air circulation is possible also in the region of the spine recession. 
         [0019]    The backrest may comprise a grip hole to allow easy carrying of the chair. The grip hole is preferably situated in the lower range, even more preferred in the lower third of the backrest. Thus it is also possible for children to carry the chair in an ergonomic and power saving manner. 
         [0020]    The shell base side may comprise a recess which is configured stronger and into which a part of a seat support can be arranged in a substantially positive fitting. 
         [0021]    Further provided is a seat shell for seating furniture, especially chairs, with a seat shell made of plastic, wherein the backrest comprises a grip hole, to which at the rear of the backrest a downwardly extending recess is adjoined, that recess being continued to the underside of the shell base side, wherein the width the recession substantially corresponds to the width of the grip hole. In the recess of the recess, the backrest has a lower thickness than in the remaining region. 
         [0022]    The recess is forming bars being substantially parallel to each another and downwardly extending, which connect ideally to the bars formed by the grip hole. The bars are continued preferably at the underside of the shell base side. 
         [0023]    Thus, both the backrest and the transition region between the seat and backrest gain additional stability, allowing in particular for plastic chairs the use of less material while maintaining high stability, which is especially necessary for school furniture. In addition, the grip hole forms of a large contact area at its top, because the recession is not maintained above the grip hole, so that an ergonomic lifting of the chair is made possible. 
         [0024]    Preferably the width of the seat shell in the transition region between the seating surface and backrest is less than the width of the seating surface and the backrest. Thus, a very popular sitting position among students, namely sitting on the chair twisted around, is supported. 
         [0025]    It has been found to be advantageous to arrange for drawn down blankets at the outer edges of the seat shell in the transition region between the seat and backrest. In case a child is sitting on the chair in a twisted position, an unpleasant sensation in the thigh area is avoided, because the blankets are a very good surface for the femur. Moreover, the rigidity of the seat shell in the transition region is further improved. 
         [0026]    The upper end edge of the backrest can be designed bead like, wherein the bead is extending substantially only at the rear of the backrest. This is on one side an additional possibility to carry the chair whereas on the other side the rigidity of the seat shell in the area of the top end edge of the backrest improves. 
         [0027]    A further advantage results from the formation of a finger grip recess in the lower region of the backrest, preferably below the seat. This makes it possible to take the chair at a low point and raise it, thus easing the raise up to higher altitudes—for example when stacking chairs. This a special advantage for smaller people, particularly school children. 
         [0028]    A hollow body is formed by the shell top and the shell base side. The shell base side may have at least one opening through which an exchange of air between the hollow body and the environment is possible. This opening in the shell base side warrants that the hardness or flexibility of the shell top and in particular the seat surface forming part of the shell top is defined substantially by the material of the shell top, without influencing the hardness or flexibility of the shell top by the internal pressure of the hollow body. 
         [0029]    In one embodiment of the invention the wall thickness of the shell top is smaller than the wall thickness of the shell base side. Thus, the shell top can be made more flexible and soft, while the shell base side is harder and stronger and takes over the function of holding the seat. The hardness or flexibility of the shell top and the shell base side can be determined essentially by the respective wall thickness. 
         [0030]    The shell base side of the seat shell may have a recess, which may be designed reinforced and in which a part of a seat support can be arranged in a substantially positive fitting. Thus, the mount of a seat support is greatly facilitated. 
         [0031]    The shell base side side and/or the shell top can be made by injection moulding, by using blowing process and/or by a cupping process and/or by a rotary casting process. Shell base side and shell top may be manufactured separately from each other, for example using the cupping process, then being connected subsequently. 
         [0032]    Preferably, the seat shell is designed in one piece. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0033]    Further details and features of the invention will become apparent from the following description in conjunction with the drawings. In the drawings: 
           [0034]      FIG. 1  shows an inventive seat shell in an isometric angular view from above; 
           [0035]      FIG. 2  shows the inventive seat shell of  FIG. 1  in a view from below; 
           [0036]      FIG. 3  shows the inventive seat shell of  FIG. 1  in a view from above; 
           [0037]      FIG. 4  shows the inventive seat shell of  FIG. 1  in a side view; 
           [0038]      FIG. 5  shows the inventive seat shell of  FIG. 1  in a view from the front; 
           [0039]      FIG. 6  shows the inventive seat shell of  FIG. 1  in a view from the rear; and 
           [0040]      FIG. 7  shows an inventive seat shell, which in arranged on a seat support, in an isometric view from below. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0041]      FIG. 1  shows an inventive seat shell in an isometric angular view from above. 
         [0042]    The seat shell  10  comprises a shell top  20  and a shell base side  30 . Preferably the seat shell is made of plastic. The shell top  20  and the shell base side  30  can be each prepared by a thermoforming or an injection molding process and are subsequently assembled. Alternatively, the seat shell  10  can be manufactured in one piece by an injection blow molding process. Alternatively, the shell top  20  may be made of a plastic material and the shell base side  30  from a stable material, such as metal. 
         [0043]    The shell top  20 , forming the seating surface  25  and that part of the back rest  26 , facing the person&#39;s back, comprises a plurality of recesses  22 . Those recesses form ventilation grooves or channels for the passage of air. 
         [0044]    In the example shown in  FIG. 1 , several elongated recesses  22  extend from the right side of the shell top  20  to the left side of the shell top  20 . Furthermore, several elongated recesses  22  extend from the rear portion of the seat surface  25  to the front area of the seat surface  25 , wherein these elongated recesses do cross those recesses extending from the right side of the shell top to the left side of the shell top  20 . Furthermore, elongated recesses across the seat surface are provided. The non-recessed portions  23  of the shell top have, according to the embodiment of the seat shell shown in  FIG. 1 , a substantially triangular shape. 
         [0045]    In another embodiment not shown here, only longitudinal recessions or only recessions transverse the seating surface may be provided. 
         [0046]    The seating surface of the shell top  20  is formed by the non-recessed regions  23 . The transitions between the recessions  22  and the non-recessed areas  23  are preferably rounded so that no unpleasant sensation is caused by the recessions when sitting on the seat shell. 
         [0047]    In addition, the top shell  20  has in the region of the backrest several elongated recessions  22  which extend from the upper region of the backrest to the lower region of the backrest. Also in the area of the back rest those recessions  22  extending from the top to the bottom  2  cross those recessions  22 , extending from right to left. Similarly, also in the region of the backrest transverse recesses  22  may be provided. The transitions between the recesses  22  and the non-recessed areas  23  are rounded also in the region of the backrest. 
         [0048]    In the area of the seating surface, recesses do have a maximum width of 20 mm. They preferably have a maximum width of 10 mm. Particularly preferred, a width of the elongated recesses  22  of about 6 mm to about 10 mm is chosen. That provides for a sufficiently good ventilation function of the seating surface respectively the shell top whereas on the other hand the elongated recesses  22  are sufficiently wide in order to allow for a proper cleaning of the recessions  22 . Moreover, depending on the surface structure, up to a maximum width of the elongated recesses  22  of 20 mm, it is ensured that no unpleasant sensation due to broad recessions  22  is created. 
         [0049]    The recessions extending from the right side of the shell top  20  to the left side of the shell top  20  preferably extend up to the right outer edge or to the left outer edge of the shell top  20  respectively so that sufficient air circulation is guaranteed, therefore allowing for a proper ventilation function of the shell top regardless of seat position. 
         [0050]    The distance between the elongated recesses is chosen so that a comfortable sitting on the seat surface, which is formed by the non-recessed regions  23 , is ensured and, at the same time, that a sufficiently good ventilation function over the entire area of the shell top  20  is ensured also. 
         [0051]    On that side of backrest of the shell top  20 , facing the dorsum, a spine recess  28  is provided, into which the spine finds clearance at least partially in order to avoid an unpleasant pressure of the backrest against the spine far as possible. The spine recess  28  has a width in the lower region of about between 30 mm and 100 mm and tapers towards the top, where it has a width of about between 20 mm and 60 mm. 
         [0052]    In a further embodiment not shown here the spine recess  28  in the lower region may also be formed more narrow than in the upper region. Also conceivable is an embodiment with a parallel spine recess  28 , that is a recess with substantially constant width. 
         [0053]    The spine recess  28  provides substantially the same depth as the elongated recesses  22  in the back rest of the shell top  20 . The spine recess  28  may also be somewhat deeper than the elongated recesses  22 . 
         [0054]    In the shell top embodiment shown here, the spine recess  28  intersects the recesses  22  extending from right to left. Thereby also in the area of the spine recess  28 , a proper ventilation is provided, as the recesses  22  extending from right to left provide for adequate air circulation in the area of the spine recess  28  also. 
         [0055]    In the embodiment shown here, the top shell  20  is configured soft, while the shell base side  30  is harder and provides the necessary stability of the seat shell  10 . The hardness of the shell top  20  and the shell base side  30  can be determined essentially by the material thickness, i.e. by the wall thickness of the shell top or the shell base side. It has been found to be advantageous to use a thin, slightly resilient material for the seat top  20 , that therefore is a material supporting a soft seat position. 
         [0056]    It is also possible to use plastic material for the shell top  20  and a stable material such as wood or metal for the shell base side  30 . Alternatively, for the manufacture of the shell top and the shell base side  30  also composite materials such as plastic mixed with hemp fibers may be used. 
         [0057]    The seat shell  10  provides for a curvature  27  in the front region of the seating surface  25 , so that the seating surface  25  forms essentially a so-called saddle seat. Thus, a student at common sitting posture, namely sitting very far forward, can be supported. 
         [0058]    The width of the seat shell in the transition region between the seat  25  and backrest  26  is smaller than that of the rest of the seat shell, i.e., less than the width of the seat surface  25  and the backrest  26 . Thus, a very popular students sitting posture, namely twisted around to sit on the chair, can be supported, because the lower part of the backrest is ergonomically advantageous placed between the thighs. A detailed view of the transition region between the seating surface  25  and backrest  26  can be seen in the  FIG. 5  and  FIG. 6 . 
         [0059]    In order to support an ergonomic and comfortable sitting when sitting rotated around also, it is advantageous when the seat shell provides for blankets  45  at its outer edges in the transition region between the seating surface  25  and the backrest  26 . The blankets  45  form an excellent surface for the femur, when a person turned around is sitting in the chair. In addition, the rigidity of the seat shell in the transition zone is also clearly improved by the blankets  45 . 
         [0060]    The backrest has a grip hole  40 , to allow for easy carrying of the chair by engaging in the grip hole. The grip hole is preferably situated in the lower range, particularly preferred in the lower third of the backrest. Therefore it is also possible for children to carry the chair in an ergonomic and power-saving manner. In addition, the grip hole  40 , which is located in the spinal recession  28 , supports air circulation in the area of the backrest  26 . 
         [0061]    The upper end edge of the backrest  26  can be configured bead like, which will be described in greater detail with reference to  FIG. 4 . In addition, a recessed grip recess  49  may be formed in the lower region of the backrest, preferably below the seat surface. Such a low-lying grip allows to take and raise the chair at a low point, which allows to more easily raise the chair to greater heights—for example in order to stack the chairs—, which is especially in schools of great advantage, where many children, due to their smaller body size, have difficulties to cope with such tasks. Particularly advantageous is the combination of a bead like upper edge of the backrest  26  with such a low lying grip recess  49 , as the chair can be handled specifically good and safe in that way. 
         [0062]      FIG. 2  shows the seat shell  10  of  FIG. 1  a view from below. 
         [0063]    Visible here is the part of the shell base side  30 , being opposite to the seating surface  25 . Also visible here is the configuration of the shell base side  30 , which allows to securely and stably attach the seat shell  10  to a seat support  35  or to a holder for a seat support. For this purpose, the lower part of the shell base side  30  provides for one or more recesses  50  into which a seat support  35  and a mounting for a seat support can be arranged with a substantially positive fit. The area of the recesses  50  can be designed more stable than the remaining area of the shell base side  30 . The seat support  35  or a bracket can be fastened by means of a screw connection to the seat shell  10 . Through the recesses  50 , a simple mounting of the seat support  35  or the bracket is supported, because the seat support can be mounted with a positive fitting into the recesses  50 , where it can remain until screwing the seat support in place. Of course it goes without saying that a conventional screw mounting, ideally with the help of additional metal plates, is possible also. 
         [0064]    Furthermore, the shell base side  30 , may, not shown here, comprise an opening which extends into the cavity between the shell top  20  and shell base side  30 . Through the opening, air may escape from the cavity of the seat shell  10 , which is particularly the case when someone sits on the (softer) shell top  20 . Through by the exchange of air between the cavity and the surrounding it is ensured that the hardness or elasticity of the shell top  20  is determined substantially by the material of the shell top  20 , as no back pressure can arise, counteracting the deformation of the shell top. 
         [0065]    Preferably, the opening is provided at the shell base side, i.e. in the area of the shell base side  30  lying opposite to the seating surface of the shell top  20 . Of course, the opening can also be arranged at the rear of the backrest, which, however, has the disadvantage that dirt can easily get into the cavity of the seat shell  10 . The diameter of the hole is ideally about 20 mm. It is also possible to use—possibly several—smaller or larger openings, whereas the openings should not be so small that noise is arising when air is flowing through the openings. 
         [0066]    In case of the use of wood or metal as a material for the shell base side  30 , the openings in the shell base side also serve to reduce the weight of the seat shell. 
         [0067]      FIG. 3  does show the seat shell  10  of  FIG. 1  in a view from above. Clearly visible here is the texture of the shell top  20  with its recessions  22  along the shell top  20 . Also visible here is the curvature  27  in the front region of the seating surface  25  which protrudes beyond the front edge of the shell top  20  so that the seat surface  25  substantially forms a so-called saddle seat. 
         [0068]      FIG. 4  does show the seat shell  10  of  FIG. 1  in a side view. At the top end edge of the backrest  26 , a bead  48  is provided which extends substantially only at the rear of the backrest  26 . Seen here is also the blanket  45  dragged down in the transition region between the seating surface  25  and the seatback  26  at the outermost right side of the seat shell  10 . The blanket  45  on one hand improves the stability or rigidity of the seat shell  10  in the transition region. On the other hand, the leg can very well rest on the blanket  45  when a person sits in the chair turned around. The blankets  45  can also be shaped in such a way, i.e. rounded, that a lifting of the chair at those blankets causes no unpleasant sensations. 
         [0069]      FIG. 5  shows the seat shell  10  of  FIG. 1  in a front view. Seen especially well here is the configuration of the transition area between the seating surface  25  and the backrest  26 . The width of the seat shell in the transition region is substantially less than in the remainder of the seat shell, so that if a person sits rotated on the chair, the transition region conveniently takes place between the thighs of the person. 
         [0070]      FIG. 6  shows the seat shell  10  of  FIG. 1  in a view from the rear. Visible are the pulled down and substantially rounded blankets  45  at the side. 
         [0071]    The backrest  26  comprises at its back of a downwardly extending recess  46  which is continued to the base side of the seating surface. The continuation of the recession  46  on the base side of the seating surface is shown in  FIG. 2 . The recession  46  is bounded above by the grip hole  40  so that the upper end of the recess  46  directly emerges into the grip hole  40 . The width of the recess  46  corresponds substantially to the width of the grip hole  40 . By the recess  46  two substantially parallel formed downwardly extending bars  47  are formed at the back side of the backrest  26 , which in the region of the grip hole  40 , that is above the grip hole, are brought together. The bars  47  are continued on the base side of the seating surface. 
         [0072]    The bars  47  will award the backrest and the transition region between the backrest and the seating surface additional stability, which is further improved by the blankets  45  pulled down at the side. An additional lower grip  49  forms a stop ridge at the same time, thus also contributing to the increased stability. 
         [0073]      FIG. 7  shows a seat shell mounted on a seat support  35  which is designed as a Z-shaped cantilever in an isometric view from a downward position. Seen here is in particular the substantially form-fitting arrangement of the seat support  35  in the recess  50  at the shell base side  30 . As an alternative to the Z-shaped cantilever, other cantilevers or other seat supports, such as four-legged seat supports may be used instead. 
       LIST OF REFERENCE NUMERALS  
       [0000]    
       
           10  seat for seating furniture 
           20  shell top 
           22  air recessions (elongated dimples) on the shell top 
           23  non recessed areas on the shell top 
           25  the part of the shell top forming the seating surface 
           26  the part of the shell top forming the backrest 
           27  curvature 
           28  vertical spine recession at the part of the shell top, forming the backrest 
           30  shell base side 
           35  seat support and seat support bracket 
           40  grip hole 
           45  pulled down blankets (to the seat, rear left and right) 
           46  recess at the rear of the backrest 
           47  vertical bars at the rear of the backrest 
           48  bead on the top end edge of the backrest 
           49  lower recessed grip 
           50  opening at the shell base side 
           60  cross strut of a seat support 
           70  connection element of a seat support