Patent Document

CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority under 35 U.S.C. §119 of German Patent Application DE 10 2009 017 601.2 filed Apr. 16, 2009, the entire contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The invention relates to a vehicle child seat for directly or indirectly fastening to a vehicle seat and/or a vehicle structure. 
     BACKGROUND OF THE INVENTION 
     Vehicle child seats, as are used for securing children in passenger vehicles, for example, are generally known. For securing the child in the child seat, either the belt system of the vehicle itself or an integrated child seat belt system is used. The child seat is positioned in the vehicle either directly onto the vehicle seat or indirectly onto a child seat base fastened in the vehicle, as is disclosed for example in DE 10 2006 011 520 A1. The fastening of the child seat and optionally of the child seat base in the vehicle takes place by means of the vehicle belt or a fastening system known by the term ISOFIX. 
     Belt tensioners for adult occupants of passenger motor vehicles are included in so-called passive safety systems. Belt tensioners tension the safety belts immediately before or during an accident. By tensioning the belt and the resulting tighter bearing of the belt against the body of the occupant, said occupant participates at an early stage in the deceleration of the vehicle and slipping down through the lap belt is prevented. In order to limit the forces produced on the occupant by means of the belt system, the belt tensioners may be combined with so-called belt force limiters which, from a defined belt force, for example, produce a specific unwinding of the belt strap from a belt retractor. 
     An optimal retaining action of a child in a vehicle child seat with an integrated belt system also requires the belt to bear as tightly as possible against the body. Thus it is also advantageous to incorporate the belt tensioning function in a child seat. 
     A vehicle child seat is disclosed in DE 197 22 096 A1 which has a retaining device consisting of an integrated belt system and belt tensioner arrangement. For triggering the belt tensioning function of the child seat, a sensor device as well as a control unit are required, of which at least the control unit is integrated outside the child seat in a fixed manner in the vehicle. When mounting the child seat in the vehicle, therefore, said child seat has to be attached by means of releasable plug connections to the control unit of the vehicle. If this inadvertently does not take place, the belt tensioning arrangement is inoperational. This fault is intended to be eliminated by additional monitoring means. 
     DE 102 51 040 A1 discloses a coupling device between the belt tensioning system of the vehicle itself and the belt system integrated in the child seat. A separate belt tensioning device is not provided in the child seat. The optimal retaining action of the child seat belt system is thus dependent on the presence of a belt tensioner in the vehicle. This is frequently not the case, however, in particular with rear seats of passenger motor vehicles, so that the use of the child seat remains restricted to specific vehicle models and/or to the front seats. 
     A vehicle child seat is disclosed in US 2007/0228787 A1 for directly fastening to a vehicle seat, comprising a backrest, a seat surface, an integrated belt system ( 10 ) for fastening a child in the vehicle child seat and a belt tensioning device comprising a trigger sensor, an energy storage device and a tensioning mechanism which, when exceeding a defined force acting on the vehicle child seat, in particular a crash force, abruptly tensions the belt system. 
     DE 20 2005 013 257 U1 discloses a belt force limiting function according to which, in the event of a crash and when exceeding a limit force, the belt is lengthened in a damped manner. A belt tensioner is not provided in this case. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to improve a vehicle child seat with a belt tensioning function, in particular with regard to its universal use and the avoidance of mounting errors. 
     According to the invention, a vehicle child seat is provided for directly or indirectly fastening to a vehicle seat and/or a vehicle structure. The vehicle child seat comprises a backrest, a seat surface, an integrated belt system for fastening a child in the vehicle child seat; and a belt tensioning device. The belt tensioning device comprises a trigger sensor, an energy storage device and a tensioning mechanism. The tensioning mechanism abruptly tensions the belt system when a force acting on the vehicle child seat exceeds a defined crash force. All components of the belt tensioning device required for the belt tensioning function are fastened to the vehicle child seat or in the vehicle child seat to form a unit therewith and to be able to be removed therewith from the vehicle. The tensioning device includes a belt force limiting means to limit the a belt force applied. The belt force limiting means is incorporated in the belt tensioning device. After triggering the belt tensioning device and upon exceeding a limit force F grenz  on the belt portion, at least one belt deflector is displaced sufficiently far in the direction of its normal position, until the force has fallen below the limit force F grenz  or the belt deflector has completely reached its normal position. 
     As all components of the belt tensioning device required for the belt tensioning function are fastened to or in the child seat and may be removed therewith from the vehicle, the child seat is able to be used universally in all vehicle models and on all seats. The attachment of the child seat to belt tensioners, sensor devices or control units integrated in the vehicle is dispensed with, whereby errors when mounting the child seat in the vehicle are avoided. The monitoring of the operating capability of the belt tensioning device may take place outside the vehicle, as the child seat represents a self-contained system. An additional belt force limiter integrated in the belt tensioning device effectively limits the belt forces acting on a child strapped into the child seat. During or immediately after the belt tensioning, individual belt portions of the belt system yield again when a limit force is exceeded, so that injuries of the child due to high belt forces are avoided. 
     In a preferred embodiment, the belt tensioning device is a mechanical system in which the trigger sensor comprises a sensor mass, the inertia force thereof triggering the belt tensioning device in the event of a crash. Due to the purely mechanical construction, no external or internal power supply is required to the child seat. 
     The energy storage device required for the belt tensioning function is preferably formed by one or more springs; in principle, the present invention, however, also includes pyrotechnical, hydraulic or pneumatic systems. 
     The belt tensioning in the event of a crash results from a spatial displacement of a first belt deflector, which deflects a belt portion of the integrated belt system. 
     By means of a second belt deflector a pulley block may be formed which effects a greater movement i.e. tensioning of the belt system relative to the movement of the first belt deflector. 
     The belt tensioning device is, in principle, suitable for integration in all types of child seat and for all age groups from newborns via toddlers to children up to 12 years old and for use in or counter to the direction of travel. The vehicle child seats according to the invention are, in particular, motor vehicle child seats for use in passenger motor vehicles, minibuses, buses, rail vehicles or aircraft. However, an embodiment for other vehicles, in particular bicycles is also possible. 
     The invention is described in more detail hereinafter with reference to two exemplary embodiments shown in the drawings. 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 
       In the drawings: 
         FIG. 1  is a perspective view of the vehicle child seat obliquely to the front; 
         FIG. 2  is a perspective view of the vehicle child seat obliquely to the rear; 
         FIG. 3  is a perspective view of the vehicle child seat obliquely from below, the belt tensioning device being shown simplified and schematically; 
         FIG. 4  is a schematic view of the adjusting belt path of a first exemplary embodiment in the normal state and in dashed lines in the triggered state; 
         FIG. 5  is a partially sectional view showing the belt tensioning device of the first exemplary embodiment in the normal state; 
         FIG. 6  is a partially sectional view showing the belt tensioning device of the first exemplary embodiment in the triggered state; 
         FIG. 7  is a schematic view of the adjusting belt path of a second exemplary embodiment in the normal state and in dashed lines in the triggered state; 
         FIG. 7   a  is a detail view showing a detail VII from  FIG. 7 ; 
         FIG. 7   b  is a detail view showing a detail corresponding to  FIG. 7  after the belt force limiting has taken place; 
         FIG. 8  is a partially sectional view showing a belt tensioning device of the second exemplary embodiment in the normal state; and 
         FIG. 9  is a partially sectional view showing the belt tensioning device of the second exemplary embodiment in the triggered state. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings in particular, a vehicle child seat  1  shown in  FIG. 1  for the transport of toddlers or children is positioned during mounting in the vehicle in the direction of travel, directly on the vehicle seat and fixed via the vehicle belt system which is present, in particular a 3-point belt. Alternatively, the child seat may be fastened indirectly onto the vehicle seat by means of a child seat base fastened to the vehicle seat or to the vehicle structure. In a modification of the exemplary embodiments described below, the vehicle child seat may also be fastened by means of a mechanical rapid fastening system, as is known for example by the term ISOFIX, to the vehicle seat or the child seat base. ISOFIX is standardized in the ISO standard 13216. 
     The directional information used below relates to the mounting of the vehicle child seat on the vehicle seat in the conventional direction of travel of the vehicle. 
     The structure of the child seat  1  consists of a padded plastic seat shell, which is divided substantially into backrest  3  and seat surface  5  regions, which are connected integrally to one another or alternatively are pivotable and lockable relative to one another by means of a horizontal hinge. The lateral support of the child takes place in each case by a side support  4  to the left and right of the backrest  3  and the seat surface  5 . 
     In the child seat a 5-point belt system  10  is incorporated which has a belt buckle  21 , which connects five belt portions to one another. The first belt portion is a crotch belt  11  which, starting from the belt buckle  21 , extends to the front region of the seat surface  5  and is fastened thereto. Two lower lateral belt portions, the lap belts  12 , are anchored by their lower ends in each case in the outer region of the seat surface  5 , and extend from there as far as the belt buckle  21 , where in each case they are passed through a slot-shaped through-guide  23   a  of two belt tongues  23  which may be locked to the belt buckle. In the further path of the lap belts, in the through-guides  23   a  the two lap belts  12  merge in one piece with one of two respective shoulder belts  13  which form the remaining belt portions of the 5-point belt system  10 . The shoulder belts  13  are passed in the upper region of the backrest  3  through two through-guides  14  of the backrest  3  and, as may be seen in  FIG. 2 , coupled to one another in the region of the rear side of the backrest  3  by means of a connecting element  17 . Starting from this connecting element  17  an adjusting belt  15  extends through a recess  8  shown in  FIG. 3 , of a seat bearing surface  6  located below the seat surface  5  and connected thereto in one piece, and in the front region of the seat shell bearing surface  6  is passed through said seat shell bearing surface. To this end, in the front region of the seat surface  5  a recess is formed, in which a belt securing device  16  known per se is arranged. This permits the adjusting belt to be pulled through only in the direction of the front edge of the child seat. In the other direction, the adjusting belt  15  may only be pulled by unlocking the belt securing device  16 . 
     To permit the child to be placed in and removed from the seat, by actuating an unlocking button of the belt buckle  21  the two belt tongues  23  may be removed therefrom and subsequently inserted therein and locked again. The belt system  10 , which bears against the child, may be tensioned by pulling on the adjusting belt  15  and thus adapted, in particular, to the size of the child. In this connection, the effective length of the shoulder belts  13  between the through-guides  23   a  of the belt tongues  23  and the through-guides  14  of the backrest  3  is altered so that the crotch belt  11 , the lap belts  12  as well as the shoulder belts  13  bear more tightly against the body of the child. 
     The adjusting belt  15  cooperates with a belt tensioning device  31 , which is also arranged in the recess  8  of the seat shell bearing surface  6 . In  FIG. 3 , said belt tensioning device  31  is shown schematically and simplified. Two exemplary embodiments are described hereinafter. 
       FIG. 4  shows a schematic view of the path of the adjusting belt  15  of a first exemplary embodiment in the normal state and in dashed lines in the triggered state. The adjusting belt  15  is deflected on a first belt deflector  37  of the belt tensioning device  31  positioned in the rear region of the recess  8 . Proceeding from the first belt deflector  37 , a portion of the adjusting belt  15  passes through in a freely movable manner between the belt tensioning device  31  and the seat surface  5  to the front towards the belt securing device  16  and is fixed there. The other portion of the adjusting belt  15 , starting from the first belt deflector  37 , passes behind the backrest  3  upwards and is coupled as described above to the connecting element  17 . 
     When the belt tensioning device  31  is triggered in the event of a crash, the first belt deflector  37  and thus the deflection point of the adjusting belt  15  is moved to the rear by the travel ΔL. The adjusting belt path is altered such that the length of the belt portion of the belt system  10  between the belt securing device  16  and the through-guides  14  of the shoulder belts  13  through the backrest  3  is lengthened. As the adjusting belt is fixed securely by means of the belt securing device  16 , accordingly the belt strap of the shoulder belts  13  is pulled from the front side of the backrest  3  through the through-guides  14  in the direction of the rear face of the backrest, so that less belt strap is present in front of the backrest  3 . As a result, the belt slack between a child sitting in the vehicle child seat  1  and the 5-point belt system  10  is reduced and/or eliminated. 
     The first exemplary embodiment shown in  FIG. 5  is disclosed in detail below. A support plate  33  connected below the seat surface  5  in the recess  8  of the seat shell bearing surface  6  fixedly connected to the seat surface  5 , has two guides  35  fixedly connected thereto. The guides  35  are respectively provided with a bore  35   a , which receive one respective limb  37   a  of the substantially U-shaped first belt deflector  37 , and guide said limb movably in a linear manner. One respective energy storage device  39  in the form of a spring is arranged between the guides  35  and one respective shoulder  37   b  of the limbs  37 . Preferably, the springs  39  are compression springs, which are received by the limbs  37   a  and secured against buckling. The two springs  39  act on the first belt deflector and produce in the triggered state of the belt tensioning device  31  the travel ΔL of the first belt deflector in the direction of the triggered position. In each case a second shoulder  37   c  serves as a travel limiter at the end of each limb  37 . The second shoulder  37   c  consists, for example, of a cylindrical bushing pushed on after mounting the springs  39 . 
     Between the limbs  37   a  of the first belt deflector  37 , a counter element  38  is arranged and fixedly connected thereto. The counter element  38  has a U-shape with slightly outwardly bent limbs and preferably consists of a material with a circular cross-section and a diameter of 6 mm. 
     Also fixedly connected to the support plate  33  is a housing  53  aligned approximately in the direction of travel and, in particular, of hollow cylindrical configuration. In the inside of the housing  53  a sensor mass  61  is movably guided therein. The sensor mass  61  has in the central point of its, in particular, circular cross section a bore  61   a , which extends parallel to the cylindrical alignment of the housing  53 . Through this bore  61   a  runs a cable control  57  which, with its first end, is fastened to a triggering device  41   a  of a connector  41  fastened to the support plate  33 . The connector  41  serves for locking the first belt deflector  37  in the normal position and is a locking device generally known as an “ISOFIX connector”, as is disclosed for example in DE 198 48 231 A1. In principle, however, all known locking systems are suitable as connectors  41  for locking counter elements, such as, for example, rotary latch locks. The connector  41 , the first belt deflector  37 , the guide  35  thereof and the counter element  38  represent the essential elements of the tensioning mechanism. 
     The second end of the cable control  57  is formed by a molded-on threaded rod portion  57   a , which passes through a bore of a closure  55 , which closes the end of the housing  53  remote from the first belt deflector  37 . The threaded rod portion  57   a  projecting from the housing  53  and/or the closure  55  is secured by a wing nut  59 . In the inside of the housing  53  a sensor spring  63  is supported, on the one hand, on the front face of the threaded rod and, on the other hand, on the sensor mass  61  and tensions said sensor mass against a stop  53   a  of the housing  53 . The stop  53   a  is preferably formed by a reduction in diameter in the inside of the cylindrical housing. The sensor mass  61  and the sensor spring  63  together form the trigger sensor of the belt tensioning device  31 . 
     In the event of a crash shown in  FIG. 6 , due to acceleration forces the sensor mass  61  is moved in the housing in the direction of travel, i.e. in the direction of the closure  55 , and thus tensions the spring  63 . As a result, a force is transmitted to the control cable  57 . As soon as this force exceeds the triggering force of the connector  41 , a triggering travel Δa of the triggering device  41   a  takes place and the counter element  38  and thus the first belt deflector  37  is released, which is moved due to the force of the now relaxed springs  39  into the triggered position. The triggering force of the connector  41  is understood to be the force which has to act on the triggering device  41   a  in order to overcome the spring forces and friction inside the connector  41 , and to unlock said connector. The mass of the sensor mass  61  and the triggering force of the connector  41  represent in the structural design of the trigger sensor the essential controlled variables for the triggering threshold of the belt tensioning device. 
       FIG. 7  and  FIG. 7   a  show a schematic view of the path of the adjusting belt  15  of a second exemplary embodiment in the normal state and in dashed lines in the triggered state. The adjusting belt  15  is deflected at a first belt deflector  137  of the belt tensioning device  131  positioned in the rear region of the recess  8 . Starting from the first belt deflector  137  a portion of the adjusting belt  15  passes through freely movably between the belt tensioning device  131  and the seat surface  5  to the front towards the belt securing device  16  and is fixed there. The other portion of the adjusting belt  15  starting from the first belt deflector  137  runs upwards through, in particular, a slot-shaped opening  173  of a second belt deflector connected fixedly and thus immovably to the vehicle child seat  1  behind the backrest  3  and is coupled as disclosed above to the connecting element  17 . 
     When triggering the belt tensioning device  131 , the first belt deflector  137  and thus the deflection point of the adjusting belt  15  is moved to the rear by the travel ΔL relative to the fixed second belt deflector  171 . As the adjusting belt  15  passes through the opening  173  of the second belt deflector  171 , the adjusting belt is deflected on the first belt deflector  137  preferably by approximately 150° to 180° and runs in the opposing direction as far as the opening  173  of the second belt deflector  171 . The adjusting belt  15  is again deflected thereon by preferably 80° to 130° and runs further upwards behind the backrest  3 . The adjusting belt path is deflected as a whole so that the length of the belt portion of the belt system  10  between the belt securing device  16  and the through-guides  14  of the shoulder belts  13  through the backrest  3  is lengthened. As the adjusting belt is securely fixed by means of the belt securing device  16 , accordingly the belt strap of the shoulder belts  13  is pulled through from the front side of the backrest  3  through the through-guides  14  in the direction of the rear side of the backrest, so that as in the first exemplary embodiment less belt strap is present in front of the backrest  3 . The arrangement of the first belt deflector  137  and the second belt deflector  171  and/or the relative movement thereof to one another produce a pulley block effect, through which the travel of the adjusting belt  15  behind the second belt deflector  171  is approximately double the size of the travel ΔL of the first belt deflector  137 . 
       FIG. 7   b  shows in a schematic view an additional belt force limiting function of the second exemplary embodiment. A child strapped into the child seat acts in the event of a crash on the belt system  10  with a force F, during or immediately after the belt tensioning. Corresponding reaction forces act via the belt system  10  on the body of the child and are limited as described below by the belt force limiting function. By the previously described arrangement of the first and second belt deflectors and the resulting pulley block effect, double the force F acts on the first belt deflector  137  in the direction of the original, untriggered normal position. When the force exceeds a limit force F grenz  the first belt deflector  137  is moved back sufficiently far until the force has again fallen below the limit force F grenz , or the belt deflector  137  has again completely reached its normal position. 
     The second exemplary embodiment shown in  FIG. 8  is disclosed in detail below. A housing  153  fixedly connected below the seat surface  5  in the recess  8  of the seat shell bearing surface  6  to the seat surface  5 , has a guide  135  connected thereto, in which the first belt deflector  137  in the form of a slide is received and is guided in a linear displaceable manner. Between the first belt deflector  137  and a shoulder  153   a  of the guide, an energy storage device  139  in the form of a spring is arranged. Preferably, the spring  139  is a compression spring which is secured externally by the guide  135  against buckling. The spring  139  acts upon the first belt deflector  137  and produces in the triggered state of the belt tensioning device  31  the travel ΔL of the first belt deflector  137  in the direction of the triggered position. 
     The adjusting belt  15  is guided through the opening  173  of the second belt deflector  171 , which is connected to the housing  153 . Thus the previously described belt path is implemented. 
     On the first belt deflector  137  a counter element  138  is fastened. The counter element  138  extends inside the housing  153  and has a U-shape with limbs, which are configured parallel to the guide  135  and the ends thereof are fixedly connected to the first belt deflector  137 . The counter element  138  preferably consists of a material with a circular cross-section and a diameter of 6 mm. 
     The connector  41  is located in the housing  153 , fixedly connected thereto. A sensor mass  161  is directly fastened to the triggering device  41   a  of the connector  41 , in particular screwed on. Inside the housing  153 , the sensor mass  161  is freely movable within limits, so that the necessary triggering travel Δa of the triggering device  41   a  is permitted. A sensor spring corresponding to the sensor spring  63  of the first exemplary embodiment is dispensed with in the second exemplary embodiment, so that the trigger sensor substantially consists of the sensor mass  161 . The connector  41 , the first belt deflector  137 , the guide thereof  135 , the counter element  138  and the second belt deflector  171  represent the essential elements of the tensioning mechanism. 
     In the event of a crash shown in  FIG. 9 , the inertia force of the sensor mass  161  acts directly on the triggering device  41   a . As soon as this force exceeds the triggering force of the connector  41 , said connector opens and releases the counter element  138  and thus the first belt deflector  137  which, due to the force of the now relaxed springs  139 , is moved into the triggered position. 
     After the triggering of the belt tensioning device  131 , for restoring to the normal state, the first belt deflector  137  is forced back counter to the force of the spring  139  in the guide  135  sufficiently far until the counter element  138  is again locked to the connector  41 . Thus the vehicle child seat  1  and the belt tensioning device thereof may be used repeatedly in a reversible manner. 
     While specific embodiments of the invention have been 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. 
     APPENDIX 
     List of Reference Numerals 
     
         
         Vehicle child seat 
         Backrest 
         Side support 
         Seat surface 
         Seat shell bearing surface 
         Recess 
         Belt system 
         Crotch belt 
         Lap belt 
         Shoulder belt 
         Through-guide 
         Adjusting belt 
         Belt securing device 
         Connecting element 
         Belt buckle 
         Belt tongue 
           23   a  Through-guide 
           31 ,  131  Belt tensioning device 
           33  Support plate 
           35 ,  135  Guide 
           35   a ,  135   a  Bore 
           37 ,  137  First belt deflector 
           37   a  Limb 
         
           37 
           b First shoulder  
         
           37   b  Second shoulder 
           38 ,  138  Counter element 
           39 ,  139  Energy storage device 
           41  Connector 
           41   a  Triggering device 
           53 ,  153  Housing 
           53   a ,  153   a  Stop 
           55  Closure 
           55   a  Through-hole 
           57  Cable control 
           57   a  Threaded rod 
           59  Wing nut 
           61 ,  161  Sensor mass 
           61   a  Bore 
           63  Sensor spring 
           171  Second belt deflector 
           173  Opening 
         Δa Triggering travel 
         ΔL Travel 
         F Belt force 
         F grenz  Limit force

Technology Category: 7