Abstract:
A foam part ( 5, 105, 205, 305 ), in particular for a vehicle seat, includes a first foam layer ( 11, 111, 211, 311 ) facing a user and a second foam layer ( 21, 221 ) facing away from the user. The first foam layer has a hardness and/or density that is different from the hardness or density of the second foam layer ( 21, 221 ). The first foam layer includes several comfort tubes ( 50, 150, 250, 350 ) facing the user. A method for producing such a foam part ( 5, 105, 205, 305 ) includes a first step in which the first foam layer, having the comfort tubes ( 50, 150, 250, 350 ), is foamed and a second step in which the second foam layer ( 21, 221 ) is foamed. A tool ( 500 ) for producing a foam part ( 5, 105, 205, 305 ) includes a bottom part ( 510 ), a frame ( 520 ), and a top part ( 530 ).

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a United States National Phase application of International Application PCT/EP2013/077630 and claims the benefit of priority under 35 U.S.C. §119 of German Patent Application DE 10 2013 000 244.3 filed on Jan. 4, 2013, DE 10 2013 002 826.4 filed on Feb. 15, 2013 and DE 10 2013 209 465.5 filed on May 22, 2013, the entire contents of which are incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    The present invention to a foam part, in particular for a vehicle seat, having a first foam tier which faces a user, and a second foam tier which faces away from the user, wherein the first foam tier has a hardness and/or density which is different from the second foam tier and to a method for producing the foam part and to a tool for producing the foam part. 
       BACKGROUND OF THE INVENTION 
       [0003]    By way of use, foam parts for vehicle seats, which serve as upholstery for the seat structure and are to offer the user of the vehicle seat as good a seating comfort as possible, are known. The seat upholstery mostly comprises a foam part for the seat cushion and a foam part for the seat back, which is separate from the former. Each of the two foam parts has a central region and two side panels. In the case of a foam part for the seat cushion, the central region of the foam part supports the buttocks and the rear sides of the thighs of the occupant of the vehicle seat in the downward direction, while the two side panels laterally bear on in each case one thigh and, on account thereof, may absorb transverse forces acting on the occupant, in particular when cornering. In the case of a foam part for the seat back, the central region of the foam part supports the back of the occupant in a rearward direction, while the two side panels laterally bear on the back and, on account thereof, may absorb transverse forces acting on the occupant. 
         [0004]    EP 1 068 094 B1 discloses a foam part having for increased comfort a plurality of mutually adjacent tubular portions which are molded onto a main body of the foam part and extend upward in a substantially perpendicular manner to the seat face away from the main body. As the occupant sits down, the tubular portions are initially compressed while the main body is only insubstantially deformed. It is only after significant deformation of the tubular portions that the main body is more intensely compressed. On account thereof, a dual-stage behavior with progressive upholstery hardness is achieved while sitting down. 
         [0005]    Dual-zone foams in which by way of use of various foam materials the central region is configured so as to be softer than the side panels are known from the prior art. On account thereof, the seating comfort is to be increased on the one hand, and the lateral support for the user is to be improved on the other hand To this end, cut foam supports are often used in the central region and hard foam inserts are used in the side panels. In order to avoid submarining of the user under the lap belt in the event of a crash, an anti-submarining function is often provided by an additional component made from a granulated foam material, for example EPP (expanded polypropylene). The additional components mentioned increase costs and reduce durability of the foam parts. Moreover, foam thicknesses are limited in terms of thinness. 
         [0006]    A foam part having a first region of foam of a first composition and a second region of foam of a second composition is known from WO 01/74557 A1, wherein a meshwork of polyethylene, jute, gauze, non-woven material or the like is disposed between the first and the second region. However, this foam part does not meet the highest requirements in terms of comfort while sitting down, in particular not when a very soft upholstery layer is desired when initially sitting down. A comparable upholstery construction is also known from WO 2010/102785 A2. 
         [0007]    A combination of tubular portions, as is known from EP 1 068 094 B1, and a horizontal separation plane between a first region of the foam part having a first composition and a second region of the foam part having a second composition, as is known from WO 01/74557 A1, is considered impossible to produce. Avoiding air pockets which compromise quality is considered to be impossible to achieve. Likewise, rupturing of the foam part in the region of the separation plane is suspected during demolding of the tubes, in particular when the tubes are continuously hollow for the purpose of seat air-conditioning and a separating non-woven material in the separation plane has to be correspondingly perforated. 
       SUMMARY OF THE INVENTION 
       [0008]    The invention is based on an object of improving a foam part of the type mentioned at the outset, in particular of improving comfort and of lowering production costs by reducing components, and of providing a method and a tool for producing such a foam part. 
         [0009]    On account of the first foam tier having a hardness and/or density which is different from the second foam tier and of a plurality of comfort tubes which face the user being provided, comfort can be improved. A hysteresis in the contraction and rebound of the foam part and vibration damping can be better adapted to customer requirements. Additional cut foam supports and hard foam inserts in the side panels, and the adhesive processes which are required in part therefor, may be dispensed with. Moreover, on account thereof, excellent durability is achieved. Reduced foam thicknesses and, on account thereof, reduced foam-part weight become possible. An additional EPP component for ensuring an anti-submarining function may be dispensed with. 
         [0010]    The term comfort tube is understood to be an elevated foam-part region which faces the occupant and which may have the most varied geometry. The comfort tubes in the upholstery regions which face the occupant form freestanding elevations in relation to a main body of the foam part. 
         [0011]    The comfort tubes may be configured so as to be hollow inside, for example for the purposes of seat air-conditioning, or may be composed of solid material. In the case of comfort tubes which are configured so as to be hollow inside, cylindrical holes run through the comfort tubes and through a main body of the foam part which bears the comfort tubes. A comfort tube here may have no holes, or one or two holes which are offset in relation to one another and which run parallel with one another. 
         [0012]    The holes may completely run through the foam part, such that air from the lower side of the foam part may flow through the holes to the upper side of the foam part. Alternatively, at least one hole is configured as a blind hole which does not completely run through the foam part, but only through the region of the associated comfort tube, for example. 
         [0013]    Preferably, the holes are configured so as to be cylindrical, in particular circular-cylindrical. On account thereof, the holes may be produced with simple means. 
         [0014]    The compliancy of an individual comfort tube may also be influenced in a targeted manner by providing a plurality of holes. Preferably, comfort tubes having a plurality of holes are disposed in the region of the seat center, when viewed perpendicularly to the driving direction. 
         [0015]    Optimizing seating comfort in terms of the hardness of the foam parts and optimizing seat ventilation often represent competing objectives when designing foam parts. This conflict of objectives may be avoided in that individual holes of the comfort tubes are configured as blind holes, that is to say that they do not completely run through the foam part. While the blind holes do not offer air circulation through the foam part, a comfort tube having a blind hole does have less compliancy in comparison with a comfort tube having a continuous hole. 
         [0016]    The outer contours of the cross sections of the comfort tubes in principle may have all known cross sections of solid bodies, and in particular may be implemented in a round, polygonal, honeycomb-shaped manner, or as described in EP 1 068 094 B1. The outer contours of the comfort tubes are independent from the cross sections of the holes, such that a square comfort tube may have an oval hole, for example. 
         [0017]    A preconception widely held in relevant expert circles that a combination of comfort tubes and a foam part which is composed of two foam tiers is not producible has been overcome. 
         [0018]    An exact separation of the foam-part regions between the first foam tier and the second foam tier may be achieved by way of a planar meshwork between the foam tiers, in particular a meshwork of polyethylene, jute, gauze, or non-woven material. Ideally, the meshwork during the foaming process is to a modest extent permeable to the foam material, on account of which a fixed connection between the foam tiers and the meshwork is created. The term meshwork is also to be understood to include all textile cloths, woven fabrics, warp-knitted fabrics, and non-woven materials which are known per se. 
         [0019]    The meshwork of a foam part designed so as to be comfortable preferably lies between the first foam tier and the second foam tier in an almost horizontal plane of the foam part. The term horizontal here does not mean the mathematically exact horizontal position within a vehicle, but all planes which are almost parallel with that surface of the respective foam part that faces the seat occupant. Seat-back upholstery may thus have a horizontal plane which in the vehicle can even be almost vertically oriented. However, in the tool the horizontal plane is mostly almost horizontal. The horizontal plane here need not be mathematically planar, that is to say two-dimensional, but may also have a slightly three-dimensional shaping having bulges and slight elevations and depressions. 
         [0020]    If and when the meshwork is disposed in a region of the lowermost points of depressions between at least two comfort tubes, the comfort tubes are initially substantially compressed as the occupant sits down. In the further process of sitting down, the second foam tier is also significantly compressed. On account thereof, a dual-stage behavior with progressive upholstery hardness is achieved while sitting down. 
         [0021]    A triple-stage behavior with progressive upholstery hardness while sitting down is achieved in that the meshwork is disposed in a region which is significantly below the depressions between the at least two comfort tubes. In comparison with the afore-described variant having dual-stage behavior while sitting down, the separation plane between the two foam tiers lies deeper, that is to say is more distant from the occupant. The comfort tubes are initially substantially compressed as the occupant sits down. In the further process of sitting down, the layer of the first foam tier which is disposed below the comfort tubes is substantially compressed, the second foam tier initially not being significantly compressed. Finally, the second foam tier is then also significantly compressed. 
         [0022]    Alternatively, a triple-stage behavior when sitting down may also be achieved in that the meshwork is disposed in a region above the lowermost points of the depressions between at least two comfort tubes. 
         [0023]    A preferred covering fastening to a foam part according to the invention provides that upholstery fastening ducts are provided between individual fields of comfort tubes, through which upholstery fastening ducts the covering is fastenable to fastening means in the foam part, preferably by way of clips, wires, or hooks. Such fastening means may be metal wires embedded in the foam, which are known per se. 
         [0024]    Homogeneous distribution of the seating pressure is achieved when the comfort tubes of individual fields which are disposed in a mirror-symmetrical manner in relation to one another are disposed in a mirror-imaged manner in relation to one another. A mirror plane through an upholstery fastening duct which runs in the driving direction and in the seat center is particularly preferable here. 
         [0025]    A foam part offers particularly good lateral support to a seat occupant in that the foam part has a third foam tier which has a greater hardness and/or density than the hardness and/or density of the other two foam tiers, in particular in the region of a side panel of the foam part). 
         [0026]    A method for producing a foam part according to the invention provides that in a first step the first foam tier having the comfort tubes is foamed, and in a second step the second foam tier is foamed. 
         [0027]    A preferred tool for producing a foam part according to the invention comprises a lower part, a frame, in particular for mounting a meshwork which is configured as a non-woven material, and an upper part. 
         [0028]    The foam part according to the invention may be produced without air pockets which compromise quality and may be readily demolded, in particular if and when the method according to the invention and the tool according to the invention for producing the foam part according to the invention are used. 
         [0029]    The invention is explained in more detail in the following by means of advantageous exemplary embodiments which are illustrated in the figures. However, the invention is not limited to these exemplary embodiments. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    In the drawings: 
           [0031]      FIG. 1  is a plan view of a first exemplary embodiment which is implemented as a seat-cushion foam part; 
           [0032]      FIG. 2  is a lateral view of the first exemplary embodiment; 
           [0033]      FIG. 3  is a section through the first exemplary embodiment along the line A-A in  FIG. 1 ; 
           [0034]      FIG. 4  is a section corresponding to  FIG. 3  through a first modification of the first exemplary embodiment; 
           [0035]      FIG. 5  is a section corresponding to  FIG. 3  through a second modification of the first exemplary embodiment; 
           [0036]      FIG. 6  is a front view of a second exemplary embodiment which is implemented as a seat-back foam part; 
           [0037]      FIG. 7  is an in-principle illustration of a tool according to the invention; 
           [0038]      FIG. 8  is a schematic and perspective illustration of the tool from  FIG. 7 ; 
           [0039]      FIG. 9  is a perspective view of a third exemplary embodiment which is implemented as a seat-cushion foam part; 
           [0040]      FIG. 10  is a plan view of the third exemplary embodiment; and 
           [0041]      FIG. 11  is a plan view of a fourth exemplary embodiment. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0042]    A vehicle seat, in particular for a motor vehicle, comprises a seat cushion and a back rest. 
         [0043]    In  FIGS. 1 and 2 , a foam part  5  according to the invention for a seat cushion of the vehicle seat is illustrated as a first exemplary embodiment. The foam part  5  comprises a central region  6  and two side panels  7 . 
         [0044]    A first foam tier  11  which in the installed position of the vehicle seat is disposed so as to be almost horizontal in the event of the vehicle seat being used faces the user, such that the user by way of his/her buttocks and the rear sides of his/her thighs in part-regions is in contact with the first foam tier  11 , optionally by way of intermediate tiers of further upholstery components, in particular of a cloth or leather covering. The first foam tier  11  is preferably composed of soft foam. 
         [0045]    In the installed position, a second foam tier  21  is disposed below the first foam tier  11  and is in particular likewise almost horizontally oriented and integrally connected to the first foam tier  11 . The second foam tier  21  is composed of a foam material which in relation to the foam material of the first foam tier  11  is firmer, preferably of hard foam. 
         [0046]    In a modification of the first exemplary embodiment, the side panels  7  are composed of a third foam material. The second foam tier  21  is composed of a foam material which in relation to the foam material of the first foam tier  11  is harder. The third foam material of the side panels  7  is again harder than the foam material of the second foam tier  21 . 
         [0047]    A separation plane between the first foam tier  11  and the second foam tier  21  in the present case runs through the central region  6  as well as through the two side panels  7 . However, in modifications of the exemplary embodiment, the side panels  7  may also be entirely composed of the second foam tier  21  or of a third foam material. In this case, only the central region  6  has dual-zone foam. 
         [0048]    The two foam tiers  11 ,  21  are foamed in one tool and have hardnesses and densities which differ from one another. The two foam tiers  11  and  21  are produced from polyurethane and in particular by the MDI (methane diphenyl diisocyanate) or the TDI (toluene diisocyanate) foaming method or by a hybrid method. The foam hardnesses are preferably between 4 and 20 kPa, wherein the first foam tier  11  is closer to the lower value and the second foam tier  21  is closer to the upper value. The density of the foam tiers  11 ,  21  is preferably between 50 g/l and 95 g/l. 
         [0049]    Moreover, the central region  6  of the first foam tier  11  has a plurality of comfort tubes  50 , in the present case forty-one, which in particular are designed so as to have a rectangular cross section and which increase comfort when first sitting down and on short driving distances. By contrast, the lower and harder second foam tier  21  improves long-term comfort. 
         [0050]    The comfort tubes  50  are integrally connected to the first foam tier  11  and form those portions of the central region  6  of the foam part  5  which most directly face the seat occupant. The comfort tubes  50  are disposed so as to be substantially perpendicular to the seat face. In the present case, the cross sections of the comfort tubes  50  are rectangular having rounded edges, but said cross sections may also have any other geometric shape. Depressions  52 , the depth of which corresponds to the height of the respective comfort tubes  50  above a base area of the first foam tier  11 , lie between adjacent comfort tubes  50 . 
         [0051]    With a view to good climatic comfort, one hole  55  which completely extends through the foam part  5  is provided in each of the comfort tubes  50 . It is also possible for only some individual comfort tubes  50  to be provided with a hole  55  in a targeted manner. The continuous holes  55  enable an effective exchange of air and moisture through the foam part, specifically and advantageously also without active ventilation means, such as ventilators. This is thus a purely passive climate system. 
         [0052]    The holes  55  in the present case are configured so as to be circular-cylindrical and preferably in each case lie in a centrical manner in the associated comfort tube  50 . 
         [0053]    A meshwork which is configured so as to be a non-woven material  225  and which represents a barrier between the two foam tiers  11  and  21  is located between the two foam tiers  11  and  21 . The two foam tiers  11  and  21  are in each case connected to the non-woven material  225  in a materially integral and/or a form-fitting manner. 
         [0054]    The non-woven material  225  is preferably oriented so as to be perpendicular to the holes  55 . In the present case, the non-woven material  225  is configured so as to be planar without holes, such that the non-woven material  225  runs through the holes  55 . However, the non-woven material  225  may also be configured so as to be perforated in the region of the holes  55 . 
         [0055]      FIG. 3  shows a section through the foam part  5 . The non-woven material  225  immediately adjoins the depressions  52  between the individual comfort holes  50 , such that the comfort tubes  50  exclusively form the first foam tier  11 . When the occupant sits down, the comfort tubes  50  are initially substantially compressed. In the further process of sitting down, the second foam tier  21  is also significantly compressed. On account thereof, a dual-stage behavior with progressive upholstery hardness is achieved while sitting down. 
         [0056]    In  FIG. 4 , a first modification of the first exemplary embodiment is illustrated. In comparison with the first exemplary embodiment, the non-woven material  225  is disposed so as to be lower, such that the separation plane between the two foam tiers  11  and  21  lies lower down, that is to say is more distant from the occupant. The comfort tubes  50  are initially substantially compressed while the occupant sits down. In the further process of sitting down, that layer of the first foam tier  11  that is disposed below the comfort tubes  50  is substantially compressed, until the second foam tier  21  is finally significantly compressed. On account thereof, a triple-stage behavior with progressive upholstery hardness is achieved while sitting down. 
         [0057]    In  FIG. 5 , a second modification of the first exemplary embodiment is illustrated. In comparison with the first exemplary embodiment, the non-woven material  225  is disposed so as to be higher, such that the separation between the two foam tiers  11  and  21  lies within the comfort tubes  50 , that is to say is closer to the occupant. The upper regions of the comfort tubes  50  which belong to the first foam tier  11  are initially substantially compressed while the occupant sits down. In the further process of sitting down, the lower regions of the comfort tubes  50 , which belong to the second foam tier  21 , are also more significantly compressed, and finally also the regions of the second foam tier  21 , which lie below the comfort tubes, are compressed. On account thereof, a triple-stage behavior with progressive upholstery hardness is achieved while sitting down. 
         [0058]    A second exemplary embodiment which is illustrated in  FIG. 6  is implemented as a foam part  105  for a seat back. The foam part  105  comprises a central region  106  and two side panels  107 . The foam part  5  of the first exemplary embodiment and the foam part  105 , in the installed and use position, enclose an angle of almost about 90 degrees, for example. A first foam tier  111  of the foam part  105  in the vehicle is oriented so as to be almost vertical and, in the driving direction, oriented toward the front, such that the user by way of his/her back is in contact in part regions with the first foam tier  111 , optionally by way of intermediate tiers of further upholstery components, in particular of a cloth or leather covering. 
         [0059]    In the installed position, a second foam tier which is not visible in  FIG. 6  is disposed behind the first foam tier  111 , so as to be in particular likewise almost vertically oriented and in particular integrally connected to the first foam tier  111 . The second foam tier is preferably composed of hard foam. The first foam tier  111  and the second foam tier are foamed in one tool and have hardnesses and densities which differ from one another. 
         [0060]    Moreover, the first foam tier  111  has a plurality of comfort tubes  150  which increase comfort when first sitting down and on short driving distances. By contrast, the lower and harder second foam tier enhances long-term comfort. 
         [0061]    Depressions  152 , the depth of which corresponds to the height of the respective comfort tubes  150  above a base area of the first foam tier  111 , lie between adjacent comfort tubes  150 . 
         [0062]    With a view to good climatic comfort, one hole  155  which completely extends through the foam part  105  is provided in each tube section of the comfort tubes  150 . 
         [0063]    The first foam tier  111  and the second foam tier are preferably produced by the MDI (methane diphenyl diisocyanate) or the TDI (toluene diisocyanate) foaming method. The foam hardnesses are in typical ranges which are known per se. 
         [0064]    In a modification of the second exemplary embodiment, the foam part  105  comprises a first foam tier  111 , but no further and in particular no second foam tier. This construction is preferably selected when a very modest foam thickness of the foam part  105  is to be achieved, or a simple tool construction is to be achieved. 
         [0065]    The production of the foam parts  5  and  105  according to the invention is carried out in a tool  500 . The tool  500  comprises a key-type lower part  510 , a frame  520  which is pivotable in relation to the lower part  510  and which mounts a non-woven material  225  as an intermediate insert, and a lid-type upper part  530  which is pivotable in relation to the frame  520 . The tool contours for producing the comfort tubes  50  and  150  are provided in the lower part  510 , such that the foam part  5  in relation to its installed position in the vehicle is produced upside down. 
         [0066]    In a first foaming operation, the material for the first foam tier  11 ,  111  is filled into the lower part  510 . Subsequently, the frame  520  together with the mounted non-woven material  225  is pivoted onto the lower part  510 , such that the non-woven material  225  bears on the surface of the second foam tier  21 ,  221 . In a second foaming operation, the material for the second foam tier  21  is introduced into the space between the frame  520  and the upper part  330 , and the upper part  530  is subsequently closed. 
         [0067]    A third exemplary embodiment which is illustrated in  FIGS. 9 and 10  largely corresponds to the first exemplary embodiment, in as far as the former is not subsequently described so as to deviate therefrom. Components and contours with the same function have reference signs which in relation to the first exemplary embodiment are increased by a value of  200 . A production method and a tool for the third exemplary embodiment likewise in each case largely correspond to the afore-described production method and tool. 
         [0068]    The third exemplary embodiment is a foam part  205  for a seat cushion of the vehicle seat. The foam part  205  comprises a central region  206  and two side panels  207 . 
         [0069]    A first foam tier  211  which in the installed position of the vehicle seat is disposed so as to be almost horizontal faces the user in the event of the vehicle seat being used. The first foam tier  211  is preferably composed of soft foam. 
         [0070]    In the installed position, a second foam tier  221  is disposed below the first foam tier  211  and is in particular likewise almost horizontally oriented and integrally connected to the first foam tier  211 . The second foam tier  221  is composed of a foam material which in relation to the foam material of the first foam tier  211  is firmer, preferably of hard foam. 
         [0071]    The two foam tiers  211  and  221  are foamed in one tool and have hardnesses and densities which differ from one another. 
         [0072]    Moreover, the first foam tier  211  has a plurality of comfort tubes  250 , in the present case forty-three, which have a largely rectangular cross section. Some individual comfort tubes  250  have an almost square cross section. Depressions  252 , the depth of which corresponds to the height of the respective comfort tubes  250  above a base area of the first foam tier  211 , lie between adjacent comfort tubes  250 . 
         [0073]    The comfort tubes  250  are subdivided into three fields of immediately adjacent comfort tubes  250 . The limits of the fields are formed by upholstery fastening ducts  254 . The upholstery fastening ducts  254  offer a plurality of passages for first fastening means which are fastened to a seat covering and for second fastening means which interact with these first fastening means and are incorporated in the foam part  205 . The fastening means, such as wires and hooks, for example, which are known per se, are not illustrated in the Figures. 
         [0074]    In a front field of comfort tubes  250  which is positioned below the thighs of an occupant, that is to say in the front region of the central region  206  of the foam part  205 , in the present case seventeen comfort tubes  250  are distributed across the entire width of the central region  206 . In two further rear fields of comfort tubes  250 , which fields are in each case positioned in a region under the ischial tuberosities of the occupant, in the present case thirteen comfort tubes  250  are in each case distributed. In the transverse direction, each of the two fields lies in each case between an upholstery fastening duct  254  in the seat center and in each case one upholstery fastening duct  254  which is adjacent to one of the two side panels  207 . The distribution and the shaping of the comfort tubes  250  in the two fields are mirror-symmetrical in relation to one another. 
         [0075]    The comfort tubes  250  are integrally connected to the first foam tier  211  and form those portions of the central region  206  of the foam part  205  which most directly face the seat occupant. The comfort tubes  250  are disposed so as to be substantially perpendicular to the seat face. In the present case, the cross sections of the comfort tubes  250  are rectangular having rounded edges, but said cross sections may also have any other geometric shape. 
         [0076]    With a view to good climatic comfort, one hole  255  which completely extends through the foam part  205  is provided in some of the comfort tubes  250 . However, individual comfort tubes  250  which in the present case are disposed so as to be adjacent to the side panels  207  are formed from solid material and thus have no hole. 
         [0077]    A meshwork which is configured so as to be a non-woven material  225  and which represents a barrier between the two foam tiers  211  and  221  is located between the two foam tiers  211  and  221 . The two foam tiers  211  and  221  are in each case connected to the non-woven material  225  in a materially integral and/or a form-fitting manner. 
         [0078]    The non-woven material  225  is preferably oriented so as to be perpendicular to the holes  255 . In the present case, the non-woven material  225  is configured so as to be planar without holes, such that the non-woven material runs through the holes  255 . However, the non-woven material  225  may also be configured so as to be perforated in the region of the holes  255 . 
         [0079]    A fourth exemplary embodiment which is illustrated in  FIG. 11  largely corresponds to the first exemplary embodiment, in as far as the former is not subsequently described so as to deviate therefrom. Components and contours with the same function have reference signs which in relation to the first exemplary embodiment are increased by a value of  300 . A production method and a tool for the fourth exemplary embodiment likewise in each case largely correspond to the afore-described production method and tool. 
         [0080]    The fourth exemplary embodiment is a foam part  305  for a seat cushion of the vehicle seat. The foam part  305  comprises a central region  306  and two side panels  307 . 
         [0081]    A first foam tier  311  which in the installed position of the vehicle seat is disposed so as to be almost horizontal faces the user in the event of the vehicle seat being used. The first foam tier  311  is preferably composed of soft foam. 
         [0082]    In the installed position, a second foam tier which is not illustrated in  FIG. 11  is disposed below the first foam tier  311  and is in particular likewise almost horizontally oriented and integrally connected to the first foam tier  311 . The second foam tier is composed of a foam material which in relation to the foam material of the first foam tier  311  is firmer and/or harder, preferably of hard foam. 
         [0083]    The first foam tier  311  moreover has a plurality of comfort tubes  350  which have a largely rectangular cross section. Some individual comfort tubes  350  have an almost square cross section. Depressions  352  having variable depths lie between adjacent comfort tubes  350 . 
         [0084]    The comfort tubes  350  are subdivided into two fields of immediately adjacent comfort tubes  350 . The limits of the fields are largely formed by upholstery fastening ducts  354 . The upholstery fastening ducts  354  offer a plurality of passages for first fastening means which are fastened to a seat covering and for second fastening means which interact with these first fastening means and are incorporated in the foam part  305 . The fastening means, such as wires and hooks, for example, which are known per se, are not illustrated in  FIG. 11 . 
         [0085]    The comfort tubes  350  are integrally connected to the first foam tier  311  and form those portions of the central region  306  of the foam part  305  which most directly face the seat occupant. The comfort tubes  350  are disposed so as to be substantially perpendicular to the seat face. In the present case, the cross sections of the comfort tubes  350  are rectangular having rounded edges, but said cross sections may also have any other geometric shape. 
         [0086]    With a view to good climatic comfort, in each case one hole  355  or two holes  355  is/are provided in some of the comfort tubes  350 . In the present case, the holes  355  are configured so as to be circular-cylindrical and preferably lie in a centrical manner in the associated comfort tube  350 . Cross sections which deviate from a circular-cylindrical shape, for example polygonal cross sections or elliptical cross sections, are likewise possible. Comfort tubes  350  having two parallel holes  355  which are positioned so as to be offset in relation to one another are provided in the center of the central region  306 . 
         [0087]    Some of the holes  355  completely extend through the foam part  305 . Further holes  355  are configured as blind holes, such that the holes  355  do not completely run through the foam part  305  but preferably only through the first foam tier  311 . It is also conceivable for the holes  355  which are configured as blind holes to not completely run through the first foam tier  311 , or run into the second foam tier. Individual comfort tubes  350  which in the present case are disposed so as to be adjacent to the side panels  307  are formed from solid material and thus have no hole. 
         [0088]    By means of a combination of holes  355  which are configured as blind holes and continuous holes  355  within a foam part  305 , the seating comfort and the seating climate may be influenced in a targeted manner. 
         [0089]    In a modification of the preceding exemplary embodiments, the side panels  7 ,  107 ,  207 ,  307  are composed of a third foam material which in relation to the foam material of the second foam tier  21 ,  221  is firmer and/or harder. The separation plane between the first foam tier  311  and the second foam tier then does not run through the side panels  7 ,  107 ,  207 ,  307 . 
         [0090]    The features disclosed in the above description, the claims and the drawings both individually as well as in combination may be of relevance to the implementation of the invention in its various design embodiments. For example, a horizontal dual-zone foam, a horizontal dual-zone foam with climatic functionality, a horizontal dual-zone foam with comfort tubes and a horizontal dual-zone foam with comfort tubes and with climatic functionality may thus be formed as possible variants for the seat cushion. Blind holes may be employed in modifications of all the exemplary embodiments. 
         [0091]    Conventional dual-zone foam may also be advantageously upgraded by way of climatic functionality and/or by way of the comfort tubes. 
         [0092]    While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.