Abstract:
A sensor assembly for sensing attachment of an object to a safety bar in a vehicle. The assembly may include a movable portion positioned to move from a first position to a second position upon attachment of the object to the safety bar, and a sensor adjacent the movable portion for providing a first output when the movable portion is in the first position and a second output when the sensor is in the second position. The attachment member may allow pivotal movement of the assembly relative to the safety bar to accommodate the orientation of the object to be attached to the safety bar. A method of modifying deployment force of an airbag upon attachment of a child safety seat to safety bar in a vehicle is also provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application Ser. No. PCT/US02/15354, filed May 15, 2002 and designating the United States, and claims the benefit of the filing date of U.S. Provisional Application Ser. No. 60/291,116, filed May 15, 2001, the teachings of which applications are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to a sensor and system for sensing the presence of a child safety seat and limiting or disabling an associated air bag. 
     BACKGROUND OF THE INVENTION 
     New vehicles may be equipped with rigid safety bars affixed to the floor of the vehicle or assembled as an integral part of the seat between the top and bottom seat cushions. A car safety seat may be equipped with a mechanism, such as an attachment bar or tether strap, to secure to the rigid safety bar. As such, this provides an additional mechanism for securing a child safety seat in addition to the typically utilized vehicle seat belt. Such a safety bar may be an ISOFIX wire attachment. Safety Associations around the world are requiring such safety bars to be installed in newer vehicles. It is expected that by 2003 to 2004 every new vehicle will be equipped with such a safety bar. 
     There is concern for child safety when an air bag deploys into a forward facing child safety seat. In such instances, the air bag may cause considerable harm to the front facing child. Accordingly, there is a need in the art for a sensor that detects when a child safety seat is installed. Upon sensing the presence of such a child seat, a proper control signal is sent to the vehicle control system in order to limit or prevent deployment of the air bag. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention, a sensor assembly for sensing attachment of an object to a safety bar in a vehicle includes: a movable portion positioned to move from a first position to a second position upon attachment of the object to the safety bar; and a sensor adjacent the movable portion for providing a first output when the movable portion is in the first position and a second output when the sensor is in the second position. The assembly may include at least one attachment member for removably affixing the assembly to the safety bar. The attachment member may allow pivotal movement of the assembly relative to the safety bar to accommodate the orientation of the object to be attached to the safety bar. 
     According to another aspect of the invention, a method of modifying deployment force of an airbag upon attachment of a child safety seat to safety bar in a vehicle includes: providing a sensor assembly consistent with the invention, and providing the first and second outputs of the sensor assembly to an airbag controller for modifying the deployment force in response to the second output. The method may further include pivotally attaching the sensor assembly to the safety bar, and/or attaching the sensor assembly to the safety bar to prevent protrusion of the assembly into the passenger compartment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Advantages of the present invention will be apparent from the following detailed description of exemplary embodiments thereof, which description should be considered in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a block diagram of an exemplary child seat sensor system consistent with the present invention; 
         FIG. 2  is a view of an exemplary rigid safety bar attachment and sensor combination consistent with the invention; 
         FIG. 3  is an isometric view of an exemplary sensor consistent with the present invention attached to a rigid safety bar; 
         FIG. 4  is a plan view of an exemplary sensor consistent with the invention; 
         FIG. 5  illustrates an exemplary cover that may be utilized with a sensor consistent with the present invention; 
         FIG. 6  illustrates a funnel that may be used with a sensor consistent with the present invention to ensure ease of assembly during attachment of a child safety seat; 
         FIG. 7A  illustrates a dog style leash attachment configuration of a sensor consistent with the present invention in a position wherein the dog style leash is unattached to a safety bar; and 
         FIG. 7B  illustrates a dog style leash attachment configuration of a sensor consistent with the present invention in a position wherein the dog style leash is attached to a safety bar. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , there is illustrated a block diagram of an exemplary child seat sensor system  101  consistent with the present invention. A safety bar, e.g., an ISOFIX wire  104 , may be installed and affixed permanently to the chassis of the vehicle or to the car seat  102 . When affixed to the car seat  102 , the safety bar  104  is typically located between the top and bottom car seat cushions. As known to those skilled in the art, there may be one or more such safety bars  104  installed in each car seat. 
     Advantageously, an exemplary sensor  106  consistent with the present invention is affixed to the safety bar  104 . The sensor  106  senses whether an attachment mechanism  114 , e.g. an attachment bar or tether strap, of a child safety seat  116  is affixed to the safety bar  104 . When a child safety seat  116  is attached to the safety bar  104  via the attachment mechanism  114 , the sensor  106  provides an appropriate control signal to an air bag controller  108 . Such a controller  108  is known to those skilled in the art and may comprise state machine type logic and/or a microprocessor programmed to generate various control signals. 
     Upon receiving an appropriate control signal from the sensor  106 , the controller  108  disables or limits deployment of an air bag  112  associated with the seat to which the child safety seat  116  is attached. The controller may reduce the intensity or power of the air bag deployment so that a child in such a safety seat would not be injured if such air bag deployed. Hence, the air bag for that seat would be limited or disabled if the car encountered a condition, e.g. a collision, which would normally deploy the air bag. Once the car seat and hence the mechanism attachment to the safety bar  104  is removed, a control signal from the sensor  106  to the controller  108  indicates that normal air bag operation could resume. Electric power for the system is provided by a power source  110 , e.g. a car battery. 
     Turning to  FIG. 2 , a view of the rear of a car seat frame  200  with two exemplary safety bars  202  and  206  on opposite ends of the frame is illustrated. Each safety bar  202 ,  206  in this exemplary configuration is a generally u-shaped ISOFIX bar of approximately 6 mm in diameter. A sensor  208  consistent with the present invention is affixed to the safety bar  202 . A child safety seat  204  having first and second attachment bars  210  affixed thereto is secured to the safety bars by engagement of the attachment bars  210  with the safety bars  202 ,  206 . Either one or two sensors may be utilized when two or more safety bars are utilized. The safety bars  202  and  206  in the exemplary embodiment of  FIG. 2  fit in between the lower and upper seat cushions in a typical car seat. Those skilled in the art will recognize that the sensor could be attached to any rigid mechanism near the applicable car seat without departing from the scope of the present invention. 
     Turning to  FIG. 3 , an isometric view of an exemplary sensor  302  consistent with the present invention attached to a safety bar  308  is illustrated. A pair of attachment members  304  and  306  may be used to affix the sensor  302  to the safety bar  308 . Advantageously, the attachment members  304  and  306  permit 360-degree rotation of the sensor about an axis of rotation  301 . This enables the sensor to hinge or rotate about the same axis as a reclining upper seat cushion. In addition, this also allows for easy installation in a variety of configurations. The sensor may also be readily affixed to existing support bars in existing vehicles. 
     Turning to  FIG. 4 , a plan view of an exemplary sensor  401  consistent with the invention is illustrated. Attachment members  406  and  408  affix the sensor  401  to the safety bar  402 . A portion  404  of the sensor is configured to move in a direction parallel to the longer legs of the safety bar  402  as indicated by a direction arrow  410 . When an attachment mechanisms e.g. a child seat attachment bar, is affixed to the safety bar  402  between the attachment members  406 , 408 , the attachment mechanism depresses the portion  404 . When the attachment mechanism is removed, the portion  404  returns to its default position, e.g. as illustrated in FIG.  4 . 
     The sensor may incorporate solid-state sensor technology such as a Hall sensor  412  to sense movement of the portion  404  and, thus, the connection of the child seat attachment mechanism to the safety bar. Hall Sensors, as known by those skilled in the art, are non-contact sensors, and may be connected to the vehicle controller in a two-wire configuration. In addition or in the alternative, those skilled in the art will recognize, however, that a variety of sensing means may be used. For example, optical, magneto-resistive, fluxgate sensors etc. may be useful in connection with a sensor consistent with the present invention. It is to be understood, therefore, that the embodiments described herein are described by way of illustration, not of limitation. 
     In an embodiment including a Hall sensor, e.g. sensor  412 , the portion  404  may include a magnetic actuator. When the portion  404  is depressed upon attachment of an attachment mechanism to the safety bar, the Hall sensor may provide an output to the controller causing modification of airbag deployment. When the portion  404  is not depressed, i.e. not attachment mechanism is affixed to the safety bar, the Hall sensor may provide a different output allowing full deployment of the airbag. 
     Advantageously, the sensor  401  and its attachment members  406  and  408  may be configured to accept a variety of standard safety bars  402  including standard ISOFIX child seat connectors. The configuration also requires only a relatively small opening when the rigid support member is located beneath the bottom and top seat cushions. As such, the opening is visually non-intrusive to passengers of the vehicle. Also, the sensor  401  may hinge around the rigid support bar  402  in order to comply with the orientation of the child seat connector mechanism, e.g., an attachment bar or tether strap. Advantageously, the sensor can be assembled and attached to the safety bar after the safety bar is already affixed to the vehicle floor or seat. The sensor may also include robust mechanical packaging  407  to ensure that the sensor can withstand harsh operating conditions. The sensor  401  may also be located and configured such that service can be performed on the sensor after installation. 
     The sensor may also have drain slots to drain foreign liquids that may enter the sensor. The sensor configuration is very flexible in that it may be used on any vehicle with little modification, on any front or back seat using a rigid support bar, and with multiple child seat attachments available from a host of various child safety seats. The sensor can also be configured with integrated connector or wire harness. Also, the integrated connector may be limited in size so as not to protrude into the passenger compartment of the vehicle. The sensor may also incorporate an opening that may be made of plastic to capture the safety bar, e.g. an ISOFIX bar, child seat attachment specified by Safety Associations. 
     Turning to  FIG. 5 , there is illustrated an exemplary cover  502  that may be utilized with a sensor  504  consistent with the present invention. The cover  502  may be affixed to the front portion  503  of the sensor  504  to protect the sensor  502  from various foreign objects that may enter when the child car seat is not in use. The operator of the vehicle will remove the cover  502  before installing the car seat. In addition, the cover  502  may also include an attachment  506 , e.g., a tether strap, to the sensor to insure the cover  502  is not lost when a child car seat is not in use. As shown in  FIG. 6 , when the cover  502  illustrated in  FIG. 5  is removed an attachable funnel  602  may be utilized to insure ease of assembly during attachment of a child car seat. 
       FIG. 7A  illustrates a dog style leash attachment configuration  700  of a sensor consistent with the present invention in a position wherein the dog style leash is unattached to a safety bar  701 .  FIG. 7B  illustrates a dog style leash attachment configuration of a sensor consistent with the present invention in a position wherein the dog style leash  702  is attached to a safety bar  701 . As shown in a configuration for sensing a typical dog style leash  702 , a movable portion  704  of the sensor may be configured with a stroke A that is larger then the thickness of the leash  702 . 
     The embodiments that have been described herein, however, are but some of the several which utilize this invention and are set forth here by way of illustration but not of limitation. It is obvious that many other embodiments, which will be readily apparent to those skilled in the art, may be made without departing materially from the spirit and scope of the invention as defined in the appended claims.