Abstract:
An occupant weight sensing apparatus configured to be coupled to a vehicle seat. The apparatus includes a base configured to be connected to a vehicle, a lever pivotally connected to the base, a rocker configured to be connected to the vehicle seat, the rocker also pivotally connected to the lever, and a sensor coupled to the lever. A force applied to the seat causes pivotal movement of the lever relative to the base. The sensor detects the pivotal movement to sense the weight of the occupant.

Description:
RELATED APPLICATIONS 
       [0001]    The present application claims priority to U.S. Provisional Application No. 61/365,683 filed on Jul. 19, 2010, the entire contents of which are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    Embodiments of the invention relate to measuring the weight of an occupant sitting in the seat of a vehicle. 
         [0003]    The operation of vehicular occupant safety systems (such as airbag and seatbelt systems) is sometimes varied depending on the weight of the occupant sitting in the seat (protected by the relevant safety system). A number of weight-sensing technologies exist for this purpose. 
       SUMMARY 
       [0004]    The invention provides, among other things, an improved bracket configuration whereby occupant weight is transferred from seat rails positioned along the bottom of a seat through two brackets (one per each side of the seat) to a sensor or load cell, such as a Hall effect sensor, particularly in the form of a sensor that replaces a securing fastener such as a bolt. A specific example of such an intelligent fastener suitable for use with the brackets is available from Robert Bosch GmbH under the trademark iBolt. The sensor or load cell could also be based on other technologies such as strain gauge technologies (e.g., thick film strain gauge, thin film strain gauge, semiconductor strain gauge), eddy-current technologies, etc. The brackets are configured such that loads (i.e., a portion of the seat weight) from more than one corner of the seat are mechanically added at the sensor or load cell. 
         [0005]    The invention also provides an occupant weight sensing apparatus configured to be coupled to a vehicle seat. The apparatus includes a base configured to be connected to a vehicle, a lever pivotally connected to the base, a rocker configured to be connected to the vehicle seat, the rocker also pivotally connected to the lever, and a sensor coupled to the lever. A force applied to the seat causes pivotal movement of the lever relative to the base. The sensor detects the pivotal movement to sense the weight of the occupant. 
         [0006]    The invention also provides an occupant weight sensing apparatus configured to be coupled to a vehicle seat, the apparatus comprising: a base configured to be connected to a vehicle; a lever including a lever bracket pivotally connected to the base and configured to be connected to the vehicle seat, and a loading bracket that extends from the lever bracket; and a sensor coupled to the loading bracket, the sensor configured to detect pivotal movement of the lever relative to the base to sense the weight of the occupant. 
         [0007]    The invention also provides an occupant weight sensing apparatus configured to be coupled to a vehicle seat, the apparatus comprising: a lever configured to be pivotally connected to a vehicle; a rocker configured to be connected to the vehicle seat, the rocker also pivotally connected to the lever; and a sensor coupled to the lever, the sensor configured to detect pivotal movement of the lever relative to the base to sense the weight of the occupant. 
         [0008]    The invention also provides an occupant weight sensing apparatus configured to be coupled to a vehicle seat, the apparatus comprising: a lever including a lever bracket configured to be pivotally connected to a vehicle and configured to be connected to the vehicle seat, and a loading bracket that extends from the lever bracket; and a sensor coupled to the loading bracket, the sensor configured to detect pivotal movement of the lever relative to the base to sense the weight of the occupant. 
         [0009]    Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1A  is a perspective view of one side of the weight sensing system. 
           [0011]      FIG. 1B  is a perspective view of the other side of the weight sensing system. 
           [0012]      FIG. 2  is an exploded view of a base of the weight sensing system of  FIGS. 1A and 1B . 
           [0013]      FIG. 3  is an exploded view of a lever of the weight sensing system of  FIGS. 1A and 1B . 
           [0014]      FIG. 4  is a view similar to  FIG. 1B  without a front or rear rocker bracket. 
           [0015]      FIG. 5  is an exploded view of a front rocker bracket. 
           [0016]      FIG. 6  is an exploded view of a rear rocker bracket. 
           [0017]      FIG. 7  is a cross-sectional view along a front pivot pin. 
           [0018]      FIG. 8  is a cross-sectional view along a rear pivot pin. 
           [0019]      FIG. 9  is a cross-sectional view along a front limit pin. 
           [0020]      FIG. 10  is a cross-sectional view along a rear limit pin. 
           [0021]      FIG. 11  is a cross-sectional view through a sensor. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. 
         [0023]    The system  100  illustrated in the drawings provides an apparatus that connects a vehicle seat to the floor of the vehicle and also detects a weight of an occupant of the seat. The weight determination sensed by the system is then used to control various components and apparatuses of the vehicle including, for example, an airbag or other vehicle occupant restraint system. The system  100  is an improvement over prior systems such as described in U.S. Pat. No. 6,859,753 titled APPARATUS AND METHOD FOR MEASURING THE WEIGHT OF AN OCCUPANT IN A VEHICLE, which is incorporated herein by reference. 
         [0024]    As illustrated in  FIG. 1A , the system  100  includes a base or support bracket  101  mounted on the floor of the vehicle or attached to feet or risers that mount on the floor of the vehicle. The structure and function of the base is described in further detail below. A front lever including a front lever bracket  103  is pivotably connected to the base  101  by the front pivot pin  105 . A front rocker bracket  107  is pivotably connected to the front lever bracket  103  by the front limit pin  109 . This arrangement allows the front rocker bracket  107  to pivot relative to the front lever bracket  103  and also allows the front lever bracket  103  to pivot relative to the base  101 . The front limit pin  109 , as described further below, prevents the front lever bracket  103  from pivoting beyond a maximum pivot angle. The rear portion of the system includes similar corresponding components. A rear lever including a rear lever bracket  111  is pivotably connected to the base  101  by a rear pivot pin  113  and a rear rocker bracket  115  is pivotably connected to the rear lever bracket  111  by the rear limit pin  117 . 
         [0025]    The front lever also includes a front loading bracket  119  extending from the front lever bracket  103 . The front loading bracket  119  is fixedly connected to the front lever bracket, preferably by rivets, and is connected to a sensor  123  as described below. As such, when the front lever bracket  103  pivots around the front pivot pin  105 , the front loading bracket  119  is raised or lowered. This movement is detected by the sensor  123  and is used to determine the weight of an occupant of the vehicle. A corresponding rear loading bracket  121  extends from the rear lever bracket  111  and the movement of the rear loading bracket  121  is also detected by the sensor  123 . 
         [0026]    The system of  FIG. 1A  is positioned beneath a seat in a vehicle. The front rocker bracket  107  is positioned near the front of the seat and the rear rocker bracket  115  is positioned near the rear of the seat. The system  100  is positioned along the left side of the vehicle seat and a corresponding, symmetric system is installed along the right side of the vehicle seat. Each of the four corners of the vehicle seat is attached to one of the rocker brackets. For example, the left front corner of the vehicle seat is attached to the front rocker bracket  107  of the system  100  of  FIG. 1A . As illustrated in  FIG. 1B , the front rocker bracket  107  includes three apertures: a guide aperture  127 , a key-lock aperture  129 , and a threaded screw aperture  131 . To attach the vehicle seat to the front rocker bracket, pins extending from the lower track of the seat are inserted into the guide aperture  127  and the key-lock aperture  129 . The lower track is slid toward the rear of the system  100  and locks into place. The lower track is then held in place by a screw installed in the threaded aperture  131 . Similarly, two bolts on the lower track are attached to the rear rocker bracket  115  through two additional apertures  133 ,  135 . An example of a lower track and a vehicle seat are described in further detail in U.S. Pat. No. 6,859,753 which has been incorporated by reference above. 
         [0027]    In the system  100 , the sensor  123  is a hall-effect sensor which also acts as a support bolt. One example of such a sensor is available from Robert Bosch GmbH under the trademark iBolt. The sensor  123  includes a threaded bolt that extends through an aperture in the base  101  and that is secured by a threaded nut  125 . The sensor  123  is thus fixed to the base. The sensor also extends through apertures  311  in the front loading bracket  119  and in the rear loading bracket  121 , as best shown in  FIGS. 4 and 10  and as described in detail below. 
         [0028]    After the seat is attached to the rocker brackets, the system  100  both supports the seat and measures the weight of a person sitting in the seat. Weight applied to the front left corner of the vehicle seat is transferred to the front rocker bracket  107 . The force applied to the front rocker bracket  107  causes the front lever bracket  103  to pivot at the front pivot pin  105 . This pivoting movement causes the front loading bracket  119  to move upward relative to the sensor  123 . Similarly, weight applied to the rear left corner of the seat is transferred to the rear rocket bracket  115 . This force causes the rear lever bracket to pivot at the rear pivot pin  113  and causes the rear loading bracket  121  to move upward relative to the sensor  123 . Movements of the front loading bracket  119  and the rear loading bracket  121  relative to the base cause the bolt to become angled relative to the housing of the sensor  123 . This creates a hall-effect which enables the sensor  123  to detect the magnitude of forces exerted upon the iBolt. The sensor  123  detects a combined force caused by the upward movement of both the front loading bracket  119  and the rear loading bracket  121 . A signal indicative of this combined force is transmitted to a control unit (including a processor and a computer-readable memory) and is used to calculate the weight of the occupant of the seat. An example of such a calculation is described in U.S. Pat. No. 6,859,753. 
         [0029]    Although the system  100  illustrated in  FIGS. 1A and 1B  includes a hall-effect sensor in the form of an iBolt, other embodiments of the system  100  can include other types of force, motion, or strain sensors including, but not limited to a thick film strain gauge, a thin film strain gauge, a semiconductor strain gauge, eddy-current sensors, or other types of hall-effect sensors. 
         [0030]      FIG. 2  illustrates an exploded view of the base  101 . The base is formed of a single piece of metal, but is shaped to include a bottom wall  201 , a first side wall  203 , and a second side wall  205 . The second side wall  205  includes front and rear portions. Several apertures are provided through the side walls  203 ,  205  of the base  101 . A pair of rear limit pin apertures  207  and a pair of rear pivot pin apertures  209  are positioned towards the rear of the first wall  203  and the second wall  205 . Similarly, a pair of front pivot pin apertures  211  and a pair of front limit pin apertures  213  are positioned toward the front of the first wall  203  and the second wall  205 . Bushings are located inside each of these apertures to provide for smoother rotation of the pins within each aperture. Each of the bushings positioned in the front limit pin apertures  213  also extends to the outside surface of a weld plate  215 . The first side wall  203  also includes a centrally located sensor aperture  217  for receiving the bolt of the sensor  123 . 
         [0031]      FIG. 3  illustrates an exploded view of the rear lever  110 . The front lever is constructed similarly. The rear lever bracket  111  includes a first side wall  301  and a second side wall  303 . The side walls  301 ,  303  are somewhat s-shaped and combine to form the shape of a fork. The rear loading bracket  121  extends between the side walls  301 ,  303  in a narrow portion of the fork-shaped bracket. The rear loading bracket  121  is attached to the rear lever bracket  111  and held in place by a pair of rivets  305 . Alternatively, the three pieces can be welded together. Each side wall  301 ,  303  includes a limit pin aperture  307  and a pivot pin aperture  309 . The apertures  307  and  309  have therein bushings. 
         [0032]      FIG. 4  shows the base  101  without the rear lever bracket  111  and the front lever bracket  103  installed. The rear pivot pin  113  extends through both rear pivot pin apertures  307 ,  207  of the rear lever bracket  111  and the base  101 . The rear limit pin  117  extends through both rear limit pin apertures  309 ,  209  of the rear lever bracket  111  and the base  101 . 
         [0033]      FIG. 5  shows an exploded view of the front rocker bracket  107 . The front rocker bracket includes a pair of front limit pin apertures  501 . As shown in  FIG. 1A  above, the front limit pin  109  extends through the front limit pin apertures  501  to pivotably connect the front rocker bracket  107  to the front lever bracket  103 . Bushings are shown but not numbered. 
         [0034]      FIG. 6  shows an exploded view of the rear rocker bracket  115 . The rear rocker bracket  115  includes a pair of rear limit pin apertures  601 . To pivotably connect the rear rocker bracket  115  to the rear lever bracket  107 , the rear limit pin  117  is extended through the rear limit pin apertures  601 . Bushings are shown but not numbered. 
         [0035]      FIG. 7  is a cross-sectional view along the front pivot pin  105 . As described above, the front pivot pin  105  extends through the front pivot pin apertures of both the base  101  and the front lever bracket  103 . The front pivot pin  105  does not extend through the front rocker bracket  107  and, therefore, does not restrict the pivoting movement of the front rocker bracket  107 . Lateral movement of the front pivot pin  105  is restricted for example, by a nut on the end of the front pivot pin  105  or by orbital peening of the front pivot pin  105  to create a riveted joint. 
         [0036]      FIG. 8  is a cross-sectional view along the rear pivot pin  113 . Again, the rear pivot pin  113  extends through the rear pivot pin apertures of both the base  101  and the rear lever bracket  111 . The rear pivot pin  113  does not extend through the rear rocker bracket  115  and, therefore, does not restrict the pivoting movement of the rear rocker bracket  115 . Lateral movement of the rear pivot pin  113  is restricted for example, by a nut on the end of the rear pivot pin  113  or by using a rivet for the rear pivot pin  113 . 
         [0037]      FIG. 9  is a cross-sectional view along the front limit pin. The front limit pin  109  extends through the front limit pin apertures of the base  101 , the front lever bracket  103 , and the front rocker bracket  107 . Although the front limit pin apertures of the front lever bracket  103  and the front rocker bracket  107  are sized to snugly receive the front limit pin  109 , the front limit pin apertures of the base  101  are sized to leave a gap  1001  between the front limit pin and the side wall of the base  101 . As described above, this arrangement allows the front lever bracket  103  to pivot up to a maximum pivot angle. When the front lever bracket  103  reaches the maximum pivot angle, the front limit pin  109  contacts the side wall of the base  101  and closes the gap  1001 . This prevents further pivoting movement of the front lever bracket  103 . In other words, the base includes a stop surface configured to engage the pin to limit movement of the lever  103  relative to the base. Lateral movement of the front limit pin  109  is restricted for example, by a nut on the end of the front limit pin  109  or by orbital peening of the front limit pin  109  to create a riveted joint. 
         [0038]      FIG. 9  shows that the front lever bracket  103  nests inside the side walls of the base  101 , and the front rocker bracket  107  nests inside the front lever bracket  103 . Alternatively, the rocker bracket could nest outside the lever bracket. 
         [0039]      FIG. 10  is a cross-sectional view along the rear limit pin. The rear limit pin  117  extends through the rear limit pin apertures of the weld plates  215 , the base  101 , the rear lever bracket  111 , and the rear rocker bracket  115 . Although the rear limit pin apertures of the rear rocker bracket  115  and the rear lever bracket  111  are sized to snugly receive the rear limit pin  117 , the rear limit pin apertures of the base  101  are sized to leave a gap  1003  between the rear limit pin and the side wall of the base  101 . As described above, this arrangement allows the rear lever bracket  111  to pivot up to a maximum pivot angle. When the rear lever bracket  111  reaches the maximum pivot angle, the rear limit pin  117  contacts the side wall of the base  101  and closes the gap  1003 . This prevents further pivoting movement of the rear lever bracket  111 . In other words, the base includes a stop surface configured to engage the pin to limit movement of the lever  110  relative to the base. Lateral movement of the rear limit pin  117  is restricted for example, by a nut on the end of the rear limit pin  117  or by orbital peening of the rear limit pin  117  to create a riveted joint. 
         [0040]      FIG. 10  shows that the rear lever bracket  111  nests inside the side walls of the base  101  and the rear rocker bracket  115  nests inside the rear lever bracket  111 . Alternatively, the rocker bracket could nest outside the lever bracket. 
         [0041]      FIG. 11  is a cross-sectional view through the sensor  123 . The sensor includes a housing  1101  and a threaded bolt  1103  extending from the housing  1101 . The threaded bolt  1103  extends through the sensor aperture  217  of the base  101  and is secured by a threaded nut  125  on the opposite side of the sidewall of the base  101 . The housing  1101  of the sensor extends through the apertures of the front loading bracket  119  and the rear loading bracket  121 . As described above, when the front and rear loading brackets  119 ,  121  pivot, the housing  1101  of the sensor moves relative to the base  101 . This movement causes the angle of the threaded bolt  1103  to change relative to the housing  1101 . This change of angle is detected by a hall-effect sensor positioned within the housing  1101  of the sensor. 
         [0042]    It is to be understood that the examples provided above are exemplary and do not represent the only possible configuration of a system according to the invention. For example, the lever bracket and the loading bracket are described as two separate pieces that are attached by a pair of rivets. However, in some embodiments, the lever bracket and the loading bracket can be manufactured as a single piece. Furthermore, although the system is described as using an iBolt as the sensor, a system according to this invention can include any sensor that measures displacement, force, or strain. 
         [0043]    Various features and advantages of the invention are set forth in the following claims.