Abstract:
A child safety seat is provided. The safety seat includes a generally L-shaped shell having a seat bottom and a seat back, a harness assembly carried by the shell for restraining an occupant in the seat, a restraining member for receiving a latching assembly for securing the safety seat into a support position on a vehicle seat in a manner, and at least one area of predetermined reduced material thickness formed into the shell in the rearward portion of the seat bottom. The area of reduce material thickness defines a crush zone of reduced capacity to resist a downward movement-induced load on the seat bottom indicative of the sudden forward travel decceleration of the vehicle.

Description:
PRIORITY CLAIM 
       [0001]    This application claims priority to U.S. Provisional Patent Application No. 61/045,022 filed on Apr. 15, 2008, and incorporates by reference all of the subject matter disclosed therein. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    This invention relates generally to child restraint systems, and more particularly, to a child seat including a crush zone for absorbing impact energy. 
         [0003]    A child restraint system, commonly referred to as a child car seat, child safety seat or simply child seat, is used for transporting and safely restraining a child within a vehicle so as to minimize the risk of injury to the child in the event of an abrupt movement or a collision involving the vehicle. Safety is of utmost concern in the design of a child seat. Conventionally, child seats have been made for infants and young children weighing less than about 45 pounds. However, as the safety advantages of the child seats and the associated safety harnesses become better known, there is an increased need in a child seat for older children of up to 80 or 100 pounds in weight. 
         [0004]    The structural requirements of the child seat typically vary insubstantially from child to child within a relatively small weight range. As a result, conventional child seats are configured to contain children having similar sizes. In contrast, the structural requirements for containing children weighing about 80 pounds is significantly different from those weighing about 25 pounds. Therefore more than one child seat would have to be purchased for a child as they grow from about 25 pounds to about 80 pounds. 
         [0005]    Accordingly, it is recognized that a specific need exists for a child seat that is configurable to address the aforementioned concerns. More particularly, there is a specific need for a child seat that is easily configurable to contain a child as that child grows from about 25 pounds to about 80 pounds. There is a specific need for a child seat that can be configured to protect a small child from the impact of a crash and easily reconfigured to protect a much larger child from the impact of a crash. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    Therefore, it is an object of the invention to provide a child safety seat that is adapted for use for different weight children. 
         [0007]    It is another object of the invention to provide a child safety seat that is adapted to absorb energy occurring during an impact. 
         [0008]    It is another object of the invention to provide a visual indicator that the child safety seat needs to be replaced because of an impact. 
         [0009]    It is another object of the invention to provide a child safety seat having a controlled crush rate. 
         [0010]    These and other objects of the invention are disclosed below in connection with a child safety seat having a generally L-shaped shell having a seat bottom and a seat back, a harness assembly carried by the shell for restraining an occupant in the seat, a restraining member for receiving a latching assembly for securing the safety seat into a support position on a vehicle seat in a manner whereby, upon a sudden forward travel decelleration of the vehicle, the seat back of the safety seat translates forward and the seat bottom of the safety seat translates downward toward the vehicle seat, and at least one area of predetermined reduced material thickness formed into the shell in the rearward portion of the seat bottom and defining a crush zone of reduced capacity to resist a downward movement-induced load on the seat bottom indicative of the sudden forward travel decceleration of the vehicle, whereby the material in the crush zone crushes at a controlled rate for reducing the load that would otherwise be transmitted to the seat occupant. 
         [0011]    According to another embodiment of the present invention, the crush zone further defines a first crush region formed about an opening on a bottom surface of the seat bottom for receiving the harness assembly. 
         [0012]    According to another embodiment of the present invention, the first crush region has a thickness between about 0.020 inches and about 0.065 inches. 
         [0013]    According to another embodiment of the present invention, the first crush region has a thickness between about 0.025 inches and about 0.060 inches. 
         [0014]    According to another embodiment of the present invention, the first crush region has a thickness between about 0.030 inches and about 0.055 inches. 
         [0015]    According to another embodiment of the present invention, the crush zone further defines a second crush region on an outwardly facing side of the seat bottom. 
         [0016]    According to another embodiment of the present invention, the shell is blow molded. 
         [0017]    According to another embodiment of the present invention, the restraining member comprises a pair of laterally spaced apart openings in the shell for cooperatively receiving a vehicle seat belt therethough. 
         [0018]    According to another preferred embodiment, a child safety seat is provided and includes a shell having a seat bottom and an attached seat back, a harness assembly carried by the shell for restraining a child in the seat, means for receiving a latching assembly for securing the safety seat to a vehicle seat, and an area of reduce material thickness formed in a rearward portion of the seat bottom and defining a crush zone for resisting a generally downwardly extending force occurring during an impact. 
         [0019]    According to another embodiment of the present invention, the means for receiving a latching assembly comprises a pair of laterally spaced apart openings in the shell for cooperatively receiving a vehicle seat belt therethough. 
         [0020]    According to another preferred embodiment, a shell for a child safety seat is provided and includes a seat bottom and an attached seat back, and an area of reduce material thickness formed in a rearward portion of the seat bottom and defining a crush zone for resisting a generally downwardly extending force occurring during an impact. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The subject matter that is regarded as the invention may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which: 
           [0022]      FIG. 1  is an perspective three-dimensional rendering of a child seat according to one embodiment of the present invention; 
           [0023]      FIG. 2  is a side view of a shell of the child seat of  FIG. 1 ; 
           [0024]      FIG. 3  is a bottom view of the shell of  FIG. 2 ; 
           [0025]      FIG. 4  is a rear view of the shell of  FIG. 2 ; 
           [0026]      FIG. 5  is a side view of the child seat of  FIG. 1  in a first non-inclined position. 
           [0027]      FIG. 6  is a side view of the child seat of  FIG. 5  in a second inclined position. 
           [0028]      FIGS. 7-10  show graphs depicting actual crash-test data obtained using a child seat of the prior art; and 
           [0029]      FIGS. 11-14  show graphs depicting actual crash-test data obtained using a child seat of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    Referring to the drawings wherein identical reference numerals denote the same elements throughout the various views, a child restraint system, indicated generally at  20 , and commonly referred to as a child car seat, child safety seat, or child seat, is shown in  FIG. 1 . By way of example only, the child seat  20  shown and described herein is a forward-facing child seat of the type typically used to transport and safely restrain children over the age of 1 year, less than about 49 inches (124 cm) in height, and weighing between about 20 pounds (about 9 kg) and about 100 pounds (about 45 kg). 
         [0031]    In one embodiment, the child seat  20  is of a single-piece construction and is configured to be secured onto a seat within a vehicle by a vehicle seat belt or a tether that is attachable to an anchor ring formed in the vehicle. Alternatively, the child seat  20  can be a two-piece construction that includes a base and a seat portion configured to be mounted to the base. The base is configured to be secured onto a seat within a vehicle by a vehicle seat belt and the seat portion is pivotally mountable on the base such that the seat portion is movable between different recline positions. In addition, the child seat  20  may be a two-piece forward-facing child seat, commonly referred to as a child booster seat, of the type that includes a base and a seat portion adapted to be mounted on the base. Preferably, the child seat  20  is made from a relatively hard, rigid plastic or composite material, and is secured onto a seat within a vehicle by a conventional vehicle seat belt, such as a lap belt or combination lap belt and shoulder harness. 
         [0032]    In the exemplary embodiment shown, the child seat  20  defines a seat area  21  for seating a child and comprises a child seat harness  22  for restraining the child within the seat area. The harness  22  comprises a pair of adjustable shoulder and chest straps  23  that are secured to a fixed length harness buckle  24  by conventional tongues or clasps (not shown) provided on the shoulder and chest straps. The harness  22  may also comprise a pair of shoulder pads  25  and a chest clip  26  for providing additional comfort and security. Other pads, such as head and thigh pads, may be provided for additional comfort, and a removable fabric cover  27  may be placed over the child seat  20  to alleviate temperature extremes and to shield the finish of the child seat from spills and stains. The child seat  20  further comprises an adjustment strap  28  for adjusting the length (i.e. tension) of the shoulder and chest straps  23  of the harness  22  to properly fit the size of a child seated within the seat area  21 . In particular, the adjustment strap  28  may be extended (i.e. pulled) to shorten (i.e. tighten) the harness  22  around the child. If desired, the child seat  20  may be fitted with armrests  29  configured to rotate upwardly for easier entry into and exit from the seat area  21 . 
         [0033]    Referring now to  FIGS. 1 and 2 , the child seat  20  includes a shell having a back  52  and a seat bottom  54 . In one embodiment, the back  52  and the seat bottom  54  are integrally formed in a blow molding process. As used herein, the term “integrally formed” refers to components that are manufactured in the same process step such that they are joined together. It should be appreciated that the back  52  and the seat bottom  54  could be manufactured separately and subsequently assembled together to form the child seat  20 . In preferred embodiments, the thickness of the top wall  56  and the bottom wall  58  is preferably between about 0.100 and 0.400 inches, more preferably between about 0.150 and 0.350 inches, and even more preferably between about 0.180 and 0.220 inches. 
         [0034]    Referring to  FIGS. 2 and 3  showing side and bottom views of the seat  20  respectively, it should be appreciated that child seat  20  is generally symmetrical and that a description of features positioned on one side of the seat can be used to understand corresponding features formed on the other side of the seat. In one embodiment, a recessed area  92  is defined by the bottom wall of the seat  20 . Recess  92  has a slot  72  formed therein for receiving an end of the harness  22  therethrough. An end stop  76  is fitted to the end of the harness and is configured to engage an end stop region  78  defined around the slot  72  thereby preventing the end from passing through the slot  72 . 
         [0035]    The wall thickness of the end stop region  78  is chosen such that end generally does not pull into or through the slot  72  during normal use or an impact such as a vehicle crash. A first crush region  82  is defined near the slot  72  such that in the illustrated embodiment, at least a portion of the end stop region  78  is positioned between the first crush region  82  and the slot  72 . The thickness of the wall in the first crush region  82  is preferably between about 0.020 inches and about 0.065 inches; more preferably between about 0.025 inches and 0.060 inches; and even more preferably between about 0.030 inches and 0.055 inches. This thickness is usually of a smaller amount that the remaining portions of the seat shell. 
         [0036]    The first crush region  82  is configured such that during an impact event, or crash of the vehicle, energy that would otherwise be transmitted to a child seated within the child seat  20  is absorbed by the first crush region  82 . It is believed that one mechanism by which the first crush region  82  absorbs energy is that it deforms, i.e., folds, crumples, tears, or the like, when exposed to a first predetermined amount of force. It should be appreciated that the end stop region  78  could also be configured to deform when exposed to the first predetermined amount of force or a second predetermined amount of force. In other words, the crush region  82  could overlap the end stop region  78  such that the wall thickness in the overlap area is uniform or gradually transitions from a first thickness in crush region  82  to a second thickness in end stop region  78 . 
         [0037]    In one embodiment, a second crush region  84  is positioned as shown in  FIG. 2  on the side of the child seat and has a thickness that is within the ranges of thickness of the first crush region  82  as described above. It should be appreciated that the first crush region  82  and the second crush region  84  can be contiguous or can be separated by a region having a thicker wall thickness. In one embodiment, only the second crush region  84  is present. It should also be appreciated that the wall thickness of the outer wall of the seat bottom  54  portion of the shell can transition gradually from the thickness near the parting seam  59  to the crush region  84 . The first crush region  82  and the second crush region  84  are configured for cooperatively forming a controlled rate of crushing. In this manner, the first crush region  82  may be configured for relatively fast crushing under a relatively smaller downward movement-induced load, whereas the second crush region  84  may be configured for relatively slower crushing under a relatively larger downward movement-induced load. Cooperatively, the first crush region  82  and the second crush region  84  combine to form a crush zone having a predetermined reduce material thickness. 
         [0038]    The present invention can be better understood with regard to a description of its operation as follows. During normal use, a child is positioned within child seat  20  and harness  22  is fastened securely. During a head-on collision, the child remains fastened within the child seat  20 . The harness  22  pulls tight such that the end stop rests against the end stop region  78 , thereby preventing the end stop from pulling through the bottom wall of the seat child seat  20 . It is believed that the first and second crush regions  82 ,  84  are crushed as the result of the following mechanism. 
         [0039]    The child seat translates forward after the harness  22  pulls tight such that a force is transmitted upward through the seat bottom  54 . When the force reaches a predetermined minimum force, the first and second crush regions  82 ,  84  collapse, i.e., crush, and the force that would have otherwise been transmitted through the seat bottom  54  and into the child is absorbed by the first and second crush regions  82 ,  84 . Upon a sudden forward travel decelleration of the vehicle, the seat back  52  of the child seat  20  translates forward and the seat bottom of the safety seat translates downward toward the vehicle seat. 
         [0040]    As shown in  FIG. 4 , a restraining member or means for receiving a latching member are provided. These means include a pair of spaced-apart openings  62  formed on a back side  60  of the child seat  20 . The pair of spaced-apart openings  62  are operable to receive a belt  64  of the vehicle seat, or may receive a belt attached to an isofix latch known in the art. The belt  64  is installed by inserting one end through a first opening of the pair of spaced-apart openings  62  and then, by reaching underneath the fabric cover  27  on the front of the seat  20 , the belt  64  is fed out through the second opening of the pair of spaced apart openings  62 . A pivotable platform  66  may be provided on the seat bottom  54  for varying the incline of the seat  20 , but is not essential for patentability and will not be further described. 
         [0041]    As shown in  FIGS. 5 and 6 , the child safety seat  20  is mounted on a vehicle seat  30 . The embodiment shown in  FIGS. 5 and 6  represents a more commercialized finish and includes a cup holder  32  that will not be described in further detail. The pivotable platform  66  is provided and is generally pivotable such that when the pivotable platform  66  is flipped in its biased first position, the child safety seat  20  is shown generally flat relative to the vehicle seat  30 . When the pivotable platform  66  is flipped forward as shown in  FIG. 6 , the child safety seat  20  takes on a second inclined position relative to the vehicle seat  30 . 
         [0042]    The present invention can be better understood with regard to examples of crash data as shown in  FIGS. 7 through 14 . In  FIGS. 7 through 10 , line G represents force transmitted in the vertical direction; line R represents force transmitted in the side-to-side direction; line K represents force transmitted in the forward direction; and line B represents the sum of the force vectors represented by G, R, and K. The sled acceleration pulse is depicted in  FIG. 7  and  FIG. 11 . The forces acting on a child&#39;s head are depicted in  FIG. 8  and  FIG. 12 . The forces acting on the child&#39;s chest are depicted in  FIG. 9  and  FIG. 13 . The forces acting on the child about the belt  64  are depicted in  FIG. 10  and  FIG. 14 . 
         [0043]    First, a conventional child seat according formed according to the prior art was subjected to a standard test and data obtained therefrom is shown in  FIGS. 7 through 10 . As shown in  FIG. 9 , the sum of the forces transmitted through the chest had a maximum force of 66.6 g-forces. Then, a child seat formed in accordance with the present invention was subjected to the same standard test and data obtained therefrom is shown in  FIGS. 11 through 14 . As shown in  FIG. 13 , the sum of the forces transmitted through the chest had a maximum force of 49.2 g-forces. It is believed that the difference of about 17 g-forces between the sum of the forces transmitted through the chest in these two tests can be attributed to the presence of the first crush region  82  and the second crush region  84  in the second child seat tested. 
         [0044]    The data obtained for the conventional child safety seat as shown in  FIGS. 5-8  was conducted with a delta V of 13.30 m/s or 29.75 MPH, having a sled impact velocity of 51.882 MPH and HIC number of 755. The G forces acted pm the chest were 66.6 Gs. The weight of the sled used in the crash was 50 lbs and having a belt tension of 15 lbs. The test was conducted at a temperature of 22.6° C. with a humidity of 24.6%. 
         [0045]    The data obtained for the conventional child safety seat as shown in  FIGS. 9-12  was conducted with a delta V of 13.29 m/s or 29.73 MPH, having a sled impact velocity of 52.247 MPH and HIC number of 667. The G forces acted pm the chest were 49.2 Gs. The weight of the sled used in the crash was 50 lbs and having a belt tension of 15 lbs. The test was conducted at a temperature of 22.5° C. with a humidity of 27.5% 
         [0046]    In the illustrated embodiment, the geometry of the seat bottom is such that first crush region  82  and end stop region  78  are separated by a dividing wall  79  that is generally perpendicular to the outer surface of the child seat  20  that is defined by the crush region  82  and the outer surface of the bottom of the child seat that is defined by the end stop region  78 . Alternatively, these outer surfaces could be generally coplanar or the dividing wall could be positioned relative to one or both of them. It should be appreciated that the crush region  82  can be configured that outer surfaces in the crush region  82  define a plurality of geometric features such as planes, curves, walls, ribs, pleats and the like. 
         [0047]    In other embodiments, it may be possible that after the harness  22  pulls tight, the harness  22  applies a force to the end cap region end stop region  78 . The end stop region  78  then transmits the force to the first crush region  82 . When the force that is transmitted to the first crush region  82  reaches a predetermined minimum force, the first crush region  82  collapses or deforms. It should be appreciated that at least a fraction of force could be transmitted through the first crush region  82  to the second crush region  84  such that the second crush region collapses. In this manner, force that would have been transmitted to the child in the child seat  20  is instead absorbed by the deformation of the first and second crush regions  82 ,  84 . 
         [0048]    The foregoing has described a child safety seat for receiving and protecting children having a weight that falls within a wide range. The child safety seat includes an area configured to reduce impact energy transferred to a child having a weight near the low end of the range. While specific embodiments of the present invention have been described, it will be apparent to those skilled in the art that various modifications thereto can be made without departing from the spirit and scope of the invention. Accordingly, the foregoing description of the preferred embodiment of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation.