Patent Publication Number: US-7909298-B2

Title: Child seat fixing device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a national stage of PCT International Application No. PCT/EP2005/008947, filed Aug. 18, 2005, which claims priority under 35 U.S.C. §119 to German Patent Application No. 10 2004 040 573.5, filed Aug. 21, 2004, the entire disclosures of which are herein expressly incorporated by reference. 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention relates to a device for fixing a child seat to a support structure of a motor vehicle with a plastically deformable holding device, which is fixed to the support structure and has a holding element to which a fixing element, which is attached to the child seat, can be fixed. 
     The fixing element may be a fixing hook, which is attached to one end of a strap, the other end of which is fixed to the upper region of the child seat. The strap with the hook is also referred to as a Top Tether, which is used in the USA and Canada for fixing child seats to the vehicle structure. 
     German laid-open specification DE 198 00 072 A1 discloses a restraint system for a child seat, which is carried in a motor vehicle and is deposited on a seat of the motor vehicle. The child seat is provided with at least one integrated latching device which, during the fixing of the deposited child seat, enters into engagement with at least one fixing device attached to the seat or, in the vicinity thereof, to a body part of the motor vehicle and is fixed on the seat or vehicle. To improve the restraining capability of the latching or fixing device, at least one deformation element is arranged between the child seat and the seat or the body part, the deformation element plastically deforming when a predetermined force is exceeded, thereby permitting a limited forward movement of the child seat in relation to the vehicle seat in order to reduce a peak stressing of the latching and/or fixing device. 
     The German translation DE 695 11 954 T2 of European patent specification EP 0 689 955 B1 discloses a child seat fixing device, which contains an energy-absorbing plate member having a first tab and a second tab and a first edge and a second edge, which edges extend therebetween, and having a center portion which is substantially midway between the first and second tabs. 
     It is an object of the present invention to provide a device for fixing a child seat to a support structure of a motor vehicle, with a plastically deformable holding device, which is fixed to the support structure and has a holding element to which a fixing element, which is attached to the child seat, can be fixed. The fixing device permits a defined movement of the holding element during deformation of the holding device, and not just in the vehicle longitudinal direction. 
     This and other objects and advantages are achieved by the device according to the invention for fixing a child seat to a support structure of a motor vehicle, in which a plastically deformable holding device fixed to the support structure has a holding element to which a fixing element (attached to the child seat) can be fixed. The holding device has at least one bending axis, along which it can be deformed when a force, such as a tensile force, acts on it. In known child seat fixing devices, the holding element moves in the direction in which the force applied to the holding element acts, i.e., generally in the vehicle longitudinal direction. In child seat fixing devices according to the present invention, the bending axis permits a defined movement of the holding element, for example, on an arc of a circle. 
     In a further exemplary embodiment of the device, the bending axis is arranged transversely with respect to the vehicle longitudinal direction. The effect achieved by this is that the holding element moves on an arc of a circle when a tensile force is applied to the holding element. 
     In another exemplary embodiment of the device, the holding device has a plurality of bending axes, which are arranged transversely with respect to the vehicle longitudinal direction and are designed such that the holding device is successively deformed in a defined bending sequence along a particular bending axis when a force, such as a tensile force, acts on the holding element. By means of the bending sequence, kinematics can be predetermined for the holding element under load such that the holding element does not come to bear against the support structure when the holding device is deformed. 
     In another exemplary embodiment of the device, the holding device has a first bending axis, which, both in the undeformed and in the deformed state of the holding device, is arranged below the upper edge of the support structure. The holding device has a second bending axis, which, in the undeformed state of the holding device, is arranged below the upper edge of the support structure and below the first bending axis, and, in the deformed state, is arranged above the upper edge of the support structure. The distance between the bending axes may be greater than the distance of the first bending axis from the upper edge of the support structure. The effect achieved by the above-described structure is that, during deformation of the holding device, the holding element does not come to bear against the support structure. 
     In another exemplary embodiment of the device, the holding device has a fixing portion delimited by the first bending axis, a holding portion delimited by the second bending axis, and a lever portion arranged between the two bending axes. The fixing portion can have at least one through hole which serves to receive a fixing element, such as a screw. The holding portion and/or the lever portion can be provided with at least one cutout. 
     In another exemplary embodiment of the device, the holding device has a first bending axis delimiting a fixing portion, a second bending axis, and a third bending axis, delimiting a holding portion, wherein a respective lever portion is formed between the first and second bending axes and between the second and third bending axes. The three bending axes make it possible to significantly reduce the loading of the support structure. 
     In another exemplary embodiment of the device, the holding device is formed from a piece of plastically deformable sheet metal. Apertures and/or predetermined points of weakness may be provided in the sheet metal in order to restrict the level of force linearly, degressively or progressively. 
     Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a holding device, which is fixed to a support structure, in the undeformed state; 
         FIG. 2  shows the holding device from  FIG. 1  after deformation about a first bending axis; 
         FIG. 3  shows the holding device from  FIG. 1  after deformation about a second bending axis; 
         FIG. 4  shows a perspective illustration of the holding device from  FIG. 1 ; 
         FIG. 5  shows a bottom view of the holding device from  FIG. 1 ; 
         FIG. 6  shows a side view of the holding device from  FIG. 1 ; 
         FIG. 7  shows a plan view of the holding device from  FIG. 1 ; 
         FIG. 8  is a perspective illustration of a holding device with three bending axes; 
         FIG. 9  shows a side view of the holding device from  FIG. 8 ; 
         FIG. 10  shows a perspective illustration of a holding device with two bending axes, and 
         FIG. 11  shows a side view of the holding device from  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
       FIG. 1  schematically illustrates a support structure  1  of a motor vehicle. The vehicle longitudinal direction is indicated by an arrow  3 . The support structure  1  is, for example, part of the rear parcel shelf of the motor vehicle. The support structure  1  has an oblique surface  5  and an upper side  6  running horizontally. A fixing portion  8  of a holding device  10  is fixed to the oblique surface  5 . The fixing portion  8  is delimited by a first bending axis  11 , which is arranged transversely with respect to the vehicle longitudinal direction  3 . 
     The holding device  10  has a second bending axis  12 , which is likewise arranged transversely with respect to the vehicle longitudinal direction  3 . A lever portion  14 , which, in the undeformed state of the holding device  10 , bears against the fixing portion  8 , is formed between the first bending axis  11  and the second bending axis  12 . A holding portion  16 , which is arranged transversely with respect to the vehicle longitudinal direction  3 , i.e., vertically, emerges from the second bending axis  12 . A tensioning hook  18 , which is attached to a fixing element  20 , engages in the holding portion  16 . 
     The tensioning hook  18  and the fixing element  20  form a “Top Tether” which serves to fix the upper region of a child seat in the region of the upper end of the backrest of a motor vehicle seat. A Top Tether includes, for example, an upper lashing strap which is fixed to the child seat and to the support structure. Top Tethers of this type are used in the USA and Canada for fixing child seats to the vehicle structure. 
       FIG. 2  illustrates the holding device  10  in a first deformation state. A force has been applied via the tensioning hook  18  in the tensioning direction  22  to the holding portion  16  of the holding device  10 . As a result, the lever portion  14  of the holding device  10  has been deformed from the position illustrated in  FIG. 1  through approximately 90° about the first bending axis  11 . The lever portion  14  is arranged approximately at right angles to the oblique surface  5 . A deformation about the second bending axis  12  has not yet taken place. The holding portion  16  is arranged above the upper side  6  of the support structure  1  approximately parallel to the upper side  6 . This ensures that the tensioning hook  18  does not bear against the support structure  1  but rather is spaced apart therefrom. 
       FIG. 3  illustrates a second deformation state of the holding device  10 . A force has continued to be applied via the tensioning hook  18  in the tensioning direction  22  to the holding portion  16  of the holding device  10 . The further application of force has caused the lever portion  14  to deform even further about the first bending axis  11 . In addition, the holding portion  16  has been deformed in relation to the lever portion  14  about the second bending axis  12 . The holding portion  16  and the tensioning hook  18  fixed thereto are also arranged above the upper side  6  of the support structure  1  in the second deformation state of the holding device  10 , which state is illustrated in  FIG. 3 . 
     Preferred bending lines can be predetermined by the special construction of the holding device. The bending line regions may be designed in such a manner that a defined bending sequence is achieved. By means of the bending sequence, kinematics can be predetermined for the tensioning hook such that the deformation first of all takes place about the first bending axis  11 , with the tensioning hook not coming to bear against the support structure. As the level of force rises, a deformation about the second bending axis also takes place, and the holding device can stretch without the tensioning hook coming to bear against the support structure. By means of a suitable weakening of the holding device along the first bending axis and the addition of a bead in the region of the second bending axis, a reproducible bending kinematics is imposed on the holding device. 
       FIGS. 4 to 7  illustrate the holding device  10  from  FIGS. 1 to 3  on its own in different views. It can be seen in  FIGS. 4 ,  5  and  7  that a through hole  24  is provided in the fixing portion  8 , which through hole serves, for example, to receive a screw with which the holding device  10  can be fixed to the support structure. In  FIGS. 4 and 7 , it can be seen that an essentially rectangular cutout  26 , which permits the engagement of the tensioning hook, is provided in the holding portion  16 . 
       FIGS. 8 and 9  illustrate a holding device  50 , which has a fixing portion  48 , in different views. The holding device  50  has a first bending axis  51 , a second bending axis  52  and a third bending axis  53 . The bending axes  51  to  53  are arranged parallel to one another. The first bending axis  51  delimits the fixing portion  48 . A first lever portion  54  is formed between the first bending axis  51  and the second bending axis  52 . A second lever portion  55  is formed between the second bending axis  52  and the third bending axis  53 . A holding portion  56  which, like the lever portions  54  and  55 , is of essentially rectangular design emerges from the third bending axis  53 . The second lever portion  55  has an essentially rectangular cutout  58 . The first lever portion  54  has an essentially rectangular cutout  60 . The fixing portion  48  is rounded at its free end. A through hole  64  which serves to receive a fixing element is provided in the fixing portion  48 . An essentially rectangular cutout  66  is provided in the holding portion  56 . 
     The type and the design of the various portions of the holding device, such as the shaping and the position of the apertures or predetermined points of weakness, enable the level of force to be restricted linearly, degressively or progressively. The holding device  10  is of partially elastic design in order to restrict the level of force and to open up a defined path. As a result, the load to which the occupant is subjected is kept to an extent which is as small as possible. During the application of a tensile force, the tensioning hook (tether hook) avoids resting on body parts and therefore failure of the hook is avoided. The loading to which the vehicle body is subjected is reduced. It is also possible to use the holding device according to the invention for an Isofix connection. 
       FIGS. 10 and 11  illustrate a further exemplary embodiment of a holding device according to the invention in different views. A holding device  70  has an elongate fixing portion  68 , which can be fixed to a support structure (not illustrated) of a motor vehicle. The holding device  70  has a first bending axis  71  and a second bending axis  72 . The bending axes  71  and  72  are arranged parallel to each other. The first bending axis  71  delimits the central region of the fixing portion  68 . A lever portion  74  is formed between the first bending axis  71  and the second bending axis  72 . A holding portion  76  which has an essentially rectangular cutout  78  emerges from the second bending axis  72 . In the fixing portion  68 , a plurality of through holes  79  and  80  are provided in the two lateral regions and serve to receive fixing elements, such as screws, in order to fix the holding device  70  to the support structure of the motor vehicle. 
     The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.