Abstract:
An apparatus ( 10 ) is used in a vehicle having a vehicle seat ( 2 ) for a vehicle occupant and a vehicle floor pan ( 4 ) for supporting the vehicle seat ( 2 ). The apparatus ( 10 ) includes a vehicle seat frame ( 20 ), a sensor ( 99 ), and a member ( 60 ). The vehicle seat frame ( 20 ) supports a load of the vehicle occupant in the vehicle seat ( 2 ). The vehicle seat frame ( 20 ) is movable vertically upon application of a vertical load to the vehicle seat frame ( 20 ). The sensor ( 99 ) transfers the load of the vehicle occupant in the vehicle seat ( 2 ) from the vehicle seat frame ( 20 ) to the vehicle floor pan ( 4 ). The sensor ( 99 ) detects a part of the load of the vehicle occupant and provides an output signal indicative of the amount of the part of the load transferred. The member ( 60 ) damps force transferred by the vehicle seat ( 2 ) and the vehicle seat frame ( 20 ) to the vehicle floor pan ( 4 ). The member ( 60 ) is interposed between the vehicle floor pan ( 4 ) and the sensor ( 99 ).

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to an apparatus for sensing a load, and more particularly, to an apparatus for sensing the load imparted to a vehicle seat by a vehicle occupant.  
       BACKGROUND OF THE INVENTION  
       [0002]     A conventional vehicle occupant load sensing apparatus includes a load sensor placed between a corner of a vehicle seat frame and a support mount for the seat. The sensor is directly within the vertical load path of the occupant&#39;s weight and responds to the vertical loads imparted to the seat by the occupant of the seat. In addition, the sensor may respond to torque loads between the seat and the support mount. Since the seat frame and the support mount must withstand large torque loads (i.e., tilting of the seat frame during crash conditions), typically the sensor also must be constructed to withstand large torque loads.  
         [0003]     This construction exposes the sensor to large dynamic loads over short periods of time, such as during a collision to the vehicle. Thus, the sensor may not produce a reliable vertical load output signal subsequent to such a dynamic loading event.  
         [0004]     A load sensing apparatus which mitigates such dynamic loading during a dynamic loading event would eliminate the requirement of replacing the load sensing apparatus subsequent to the dynamic loading event.  
       SUMMARY OF THE INVENTION  
       [0005]     An apparatus in accordance with one aspect of the present invention is used in a vehicle having a vehicle seat for a vehicle occupant and a vehicle floor pan for supporting the vehicle seat. The apparatus includes a vehicle seat frame, a sensor, and a member. The vehicle seat frame supports a load of the vehicle occupant in the vehicle seat. The vehicle seat frame is movable vertically upon application of a vertical load to the vehicle seat frame. The sensor transfers the load of the vehicle occupant in the vehicle seat from the vehicle seat frame to the vehicle floor pan. The sensor detects a part of the load of the vehicle occupant and provides an output signal indicative of the amount of the part of the load transferred. The member damps force transferred by the vehicle seat and the vehicle seat frame to the vehicle floor pan. The member is interposed between the vehicle floor pan and the sensor.  
         [0006]     An apparatus in accordance with another aspect of the present invention is used in a vehicle having a vehicle seat for a vehicle occupant and a vehicle floor pan for supporting the vehicle seat. The apparatus includes a bracket, a sensor, and a member. The bracket supports a load of the vehicle occupant in the vehicle seat. The vehicle seat is movable vertically relative to the bracket upon application of a vertical load to the vehicle seat. The sensor transfers the load of the vehicle occupant from the vehicle seat to the vehicle floor pan. The sensor detects a part of the load of the vehicle occupant and provides an output signal indicative of the amount of the part of the load transferred. The member damps force transferred by the vehicle seat to the vehicle floor pan. The member is interposed between the vehicle floor pan and the sensor.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The foregoing and other features of the invention will become more apparent to one skilled in the art upon consideration of the following description of the invention and the accompanying drawings, in which:  
         [0008]      FIG. 1  is a schematic representation of an apparatus in accordance with the present invention;  
         [0009]      FIG. 2  is a schematic representation of one aspect of the apparatus of  FIG. 1  taken along line  2 - 2  of  FIG. 1 ;  
         [0010]      FIG. 3  is a schematic representation of the apparatus of  FIG. 2  taken along line  3 - 3  of  FIG. 2 ;  
         [0011]      FIG. 4  is a schematic representation of another aspect of the apparatus of  FIG. 1  taken along line  4 - 4  of  FIG. 1 ; and  
         [0012]      FIG. 5  is a schematic representation of the apparatus of  FIG. 4  taken along line  5 - 5  of  FIG. 4 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]     According to an aspect of the present invention, as shown in  FIGS. 1-3 , a vehicle occupant load sensing apparatus  10  is used in a vehicle having a seat  2  for the vehicle occupant. A vehicle floor pan  4  supports the vehicle seat  2 . The apparatus  10  includes a vehicle seat frame  20  for supporting the vehicle seat  2 , a sensor  99  for sensing a load placed on the vehicle seat, a resilient member  60  for absorbing dynamic loads imparted to the sensor by the vehicle seat, a bracket  30  for transmitting the load from the vehicle seat to the vehicle floor pan, an upper track  12  for supporting the bracket, and a lower track  16  for adjustably supporting the upper track.  
         [0014]     The vehicle seat frame  20  supports a weight load of the vehicle occupant in the vehicle seat  2 . During a vehicle collision, the seat frame  20  may also sustain upward and lateral loads created by the vehicle collision. The load of the vehicle occupant in the vehicle seat  2  is transmitted through the sensor  99 , the bracket  30 , upper track  12 , and lower track  16  from the vehicle seat frame  20  to the vehicle floor pan  4 .  
         [0015]     The lower track  16  is fixedly attached to the vehicle floor pan  4  in a suitable manner. The lower track  16  has two opposite side rails  17 ,  18 . The upper track  12  has two opposite rails  13 ,  14  that slidingly engage the side rails  17 ,  18  of the lower track  16 . The upper track  12  may slide on the lower track  16  for manual forward or rearward adjustment of the position of the seat  2  for occupants of varying sizes, as is known in the art. The bracket  30  is thus supported by the upper track  12  so that it is vertically stationary and does not move as a result of loads applied to the vehicle seat  2 .  
         [0016]     The bracket  30  is typically constructed of a suitable metal such as steel. The bracket  30  has a first horizontal lower portion  40  for fixed connection to the upper track  12  and a second upper horizontal portion  50  for connection to the sensor  99  through the resilient member  60 . The first portion  40  of the bracket  30  is connected to the second portion  50  of the bracket  30  by a vertical portion  55  thereby forming a C-shaped channel ( FIG. 3 ). The upper horizontal portion  50  of the bracket  30  has an upper surface  52  and a lower surface  54  opposite the upper surface. The lower horizontal portion  40  of the bracket  30  has an upper surface  42  and a lower surface  44  opposite the upper surface.  
         [0017]     The resilient member  60  is interposed between the sensor  99  and the first upper portion  50  of the bracket  30 . The resilient member  60  absorbs, or dampens, dynamic loads placed on the vehicle seat  2  thereby protecting the sensor  99 . The resilient member  60  typically a resilient bushing, is compressible and expandable as the vertical load on the seat frame  20  increases or decreases. The resilient member  60  is typically formed of rubber or other suitable elastomer.  
         [0018]     The resilient member  60  has a toroidal shape with a first upper surface  62  and a second lower surface  64  opposite the upper surface. The resilient member also has an inner annular surface  66  interconnecting the upper and lower surfaces  62 ,  64  and an outer annular surface  68  interconnecting the upper and lower surfaces. The outer annular surface  68  has an annular groove  69  for receiving the upper horizontal portion  50  of the bracket  30 .  
         [0019]     A downward limit stop bracket  80  prevents over-travel of the vehicle seat frame  20  from an excessive downward load on the vehicle seat frame  20 . The bracket  80  has an S-shape in cross-section ( FIG. 2 ) with an upper horizontal portion  82 , a lower horizontal portion  84 , and a vertical middle portion  86  interconnecting the upper and lower portions. The upper horizontal portion  82  is secured for movement with the vehicle seat frame  20  such that, when a predetermined excessive downward load is applied to the vehicle seat frame  20 , a lower surface  85  of the lower horizontal portion  84  contacts the upper surface  52  of the upper horizontal portion  50  of the bracket  30  thereby preventing further downward movement of the vehicle seat frame. The compressibility of the resilient member  60  allows this limited downward movement to occur. The predetermined excessive downward load is dependent on the material of construction of the resilient member  60 .  
         [0020]     An upward limit stop bracket  120  prevents over-travel of the vehicle seat frame  20  from an excessive upward load on the vehicle seat frame  20 . The bracket  120  has a generally annular shape with an inner annular sleeve portion  122 , an outer ring portion  124 , and an annular horizontal portion  126  interconnecting the inner and outer portions. The bracket  120  is secured for movement with the vehicle seat frame  20  such that, when a predetermined excessive upward load is applied to the vehicle seat frame  20 , an upper surface  125  of the outer ring portion  124  contacts the lower surface  54  of the upper horizontal portion  50  of the bracket  30  thereby preventing further upward movement of the vehicle seat frame. The compressibility of the resilient member  60  allows this limited upward movement to occur.  
         [0021]     The sensor  99  is typically a single bolt axial sensor which detects axial loads on it and supports the attached structure against lateral loads. One example of this type of sensor is a Texas Instruments Part Number 4WS3-1.  
         [0022]     The sensor  99  has a rectangular main body portion  101  with an electronic plug  103  extending laterally therefrom, an upper threaded stud  107  extending upward from the main body portion, and a lower threaded stud  109  extending downward from the main body portion. The two studs  107 ,  109  lie on a single axis  991 . The main body portion  101  has an upper horizontal surface  111  from which the upper stud  107  extends and a lower horizontal surface  113  from which the lower stud  109  extends.  
         [0023]     An upper fastener member  140 , typically a nut, and a lower fastener member  150 , typically a nut, secures the apparatus  10  together. The upper threaded stud  107  of the sensor  99  extends upward from the main body portion  101  through a bore in the upper horizontal portion  82  of the bracket  80  and a bore in the vehicle seat frame  20  to the upper fastener member  140 .  
         [0024]     The upper surface  111  of the main body portion  101  of the sensor  99  engages a lower surface  821  of the upper horizontal portion  80  of the bracket  80 . An upper surface  822  of the upper horizontal portion  82  of the bracket  80  engages a lower surface  21  of the vehicle seat frame  20 . An upper surface  22  of the vehicle seat frame  20  engages the upper fastener member  140 .  
         [0025]     The lower threaded stud  109  extends downward from the main body portion  101  simultaneously through a bore defined by the inner annular sleeve portion  122  of the bracket  120  and a bore defined by the inner annular surface  66  of the resilient member  60  to the lower fastener member  150 .  
         [0026]     The lower surface  113  of the main body portion  101  of the sensor  99  engages the upper surface  62  of the resilient member  60 . The lower surface  64  of the resilient member  60  engages an upper surface  127  of the annular horizontal portion  126  of the bracket  120 . A lower surface  129  of the annular horizontal portion  126  of the bracket  120  engages the lower fastener member  150 .  
         [0027]     The two fasteners  140 ,  150  together secure the resilient member  60  in a compressed condition. Thus, part of the resilient member  60  compresses and part of the resilient member expands when a vertical load is placed on the vehicle seat frame  20 .  
         [0028]     When a downward load is placed on the seat frame  20 , the portion  601  of the resilient member  60  between the lower surface  113  of the sensor  99  and the upper surface  52  of the upper portion  50  of the bracket  30  compresses while the sensor  99  senses the downward load. As stated above, the portion  601  of the resilient member  60  mitigates any downward dynamic load, or spike, that may be imparted to the apparatus  10  during a collision or other such condition.  
         [0029]     When an upward load is placed on the seat frame  20 , the portion  603  of the resilient member  60  between the lower surface  54  of the upper portion  50  of the bracket  30  and the upper surface  127  of the horizontal portion  126  of the bracket  120  compresses while the sensor  99  senses up the upward load. As stated above, the portion  603  of the resilient member  60  mitigates any downward dynamic load, or spike, that may be imparted to the apparatus  10  during a collision or other such condition.  
         [0030]     According to a second aspect of the present invention, as shown in  FIGS. 1 and 4 - 5 , a vehicle occupant load sensing apparatus  210  is used in a vehicle having a seat  202  for the vehicle occupant. A vehicle floor pan  204  supports the vehicle seat  202 . The apparatus  210  includes a vehicle seat frame  220  for supporting the vehicle seat  202 , a sensor  299  for sensing a load placed on the vehicle seat, a resilient member assembly  260  for absorbing dynamic loads imparted to the sensor by the vehicle seat, a bracket  230  for transmitting the load from the vehicle seat to the vehicle floor pan, an upper track  212  for supporting the bracket, and a lower track  216  for adjustably supporting the upper track.  
         [0031]     The vehicle seat frame  220  supports a weight load of the vehicle occupant in the vehicle seat  202 . During a vehicle collision, the seat frame  220  may also sustain upward and lateral loads created by the vehicle collision. The load of the vehicle occupant in the vehicle seat  202  is transmitted through the sensor  299 , the bracket  230 , upper track  212 , and lower track  216  from the vehicle seat frame  220  to the vehicle floor pan  204 .  
         [0032]     The lower track  216  is fixedly attached to the vehicle floor pan  204  in a suitable manner. The lower track  216  has two opposite side rails  217 ,  218 . The upper track  212  has two opposite rails  213 ,  214  that slidingly engage the side rails  217 ,  218  of the lower track  216 . The upper track  212  may slide on the lower track  216  for manual forward or rearward adjustment of the position of the seat  202  for occupants of varying sizes, as is known in the art. The bracket  230  is thus supported by the upper track  212  so that it is vertically stationary and does not move as a result of loads applied to the vehicle seat  202 .  
         [0033]     The bracket  230  is typically constructed of a suitable metal such as steel. The bracket  230  has a first horizontal lower portion  240  for fixed connection to the upper track  212  and a second upper horizontal portion  250  for connection to the sensor  299  through the resilient member assembly  260 . The first portion  240  of the bracket  230  is connected to the second portion  250  of the bracket  230  by a vertical portion  255  thereby forming a C-shaped channel ( FIG. 5 ). The upper horizontal portion  250  of the bracket  230  has an upper surface  252  and a lower surface  254  opposite the upper surface. The lower horizontal portion  240  of the bracket  230  has an upper surface  242  and a lower surface  244  opposite the upper surface.  
         [0034]     The resilient member assembly  260  is interposed between the sensor  299  and the first upper portion  250  of the bracket  230 . The resilient member assembly  260  absorbs, or dampens, dynamic loads placed on the vehicle seat  202  thereby protecting the sensor  99 . The resilient member assembly  260 , typically two annular resilient bushings, is compressible and expandable as the vertical load on the seat frame  220  increases or decreases. The resilient member assembly  260  is typically formed of rubber or other suitable elastomer.  
         [0035]     The resilient member assembly  260  has a first upper member  261  and a second lower member  262 . The first and second members  261 ,  262  are symmetric about the upper horizontal portion  250  of the bracket  230 , thereby together forming a resilient member similar to resilient member  60  of  FIGS. 2 &amp; 3 . Together the members  261 ,  262  form a toroidal shape with a first upper surface  263  and a second lower surface  264  opposite the upper surface ( FIG. 5 ). The resilient member assembly  260  also has an inner annular surface  266  interconnecting the upper and lower surfaces  263 ,  264  and an outer annular surface  268  interconnecting the upper and lower surfaces. The outer annular surface  268  has an annular groove  269  for receiving the upper horizontal portion  250  of the bracket  230 .  
         [0036]     A downward limit stop bracket  280  prevents over-travel of the vehicle seat frame  220  from an excessive downward load on the vehicle seat frame  220 . The bracket  280  has an S-shape in cross-section ( FIG. 4 ) with an upper horizontal portion  282 , a lower horizontal portion  284 , and a vertical middle portion  286  interconnecting the upper and lower portions. The upper horizontal portion  282  is secured for movement with the vehicle seat frame  220  such that, when a predetermined excessive downward load is applied to the vehicle seat frame  220 , a lower surface  285  of the lower horizontal portion  284  contacts the upper surface  252  of the upper horizontal portion  250  of the bracket  230  thereby preventing further downward movement of the vehicle seat frame. The compressibility of the resilient member assembly  260  allows this limited downward movement to occur. The predetermined excessive downward load is dependent on the material of construction of the resilient member assembly  260 .  
         [0037]     A limit stop bracket assembly  320  prevents over-travel of the vehicle seat frame  220  from an excessive load on the vehicle seat frame  320 . The bracket assembly  320  has an upper bracket member  321  and a lower bracket member  322 . The bracket members  321 ,  322  are symmetric about the upper horizontal portion  250  of the bracket  230  ( FIGS. 4 &amp; 5 ). Together the bracket members  321 ,  322  have a generally annular shape with an inner annular sleeve portion  323 , an upper outer ring portion  324 , a lower outer ring portion  325 , an upper annular horizontal portion  326  interconnecting the inner sleeve portion and the upper outer ring portion, and a lower annular horizontal portion  327  interconnecting the inner sleeve portion and the lower outer ring portion.  
         [0038]     The bracket assembly  320  is secured for movement with the vehicle seat frame  220  such that, when a predetermined excessive downward load is applied to the vehicle seat frame  220 , a lower surface  328  of the upper outer ring portion  324  contacts the upper surface  254  of the upper horizontal portion  250  of the bracket  230  thereby preventing further downward movement of the vehicle seat frame. The compressibility of the upper resilient member  261  allows this limited downward movement to occur.  
         [0039]     Similarly, bracket assembly  320  is secured for movement with the vehicle seat frame  220  such that, when a predetermined excessive upward load is applied to the vehicle seat frame  220 , an upper surface  329  of the lower outer ring portion  325  contacts the lower surface  254  of the upper horizontal portion  250  of the bracket  230  thereby preventing further upward movement of the vehicle seat frame. The compressibility of the lower resilient member  262  allows this limited downward movement to occur.  
         [0040]     The sensor  299  is typically a single bolt axial sensor which detects axial loads on it and supports the attached structure against lateral loads. One example of this type of sensor is a Texas Instruments Part Number 4WS3-1.  
         [0041]     The sensor  299  has a rectangular main body portion  301  with an electronic plug  303  extending laterally therefrom, an upper threaded stud  307  extending upward from the main body portion, and a lower threaded stud  309  extending downward from the main body portion. The two studs  307 ,  309  lie on a single axis  992 . The main body portion  301  has an upper horizontal surface  311  from which the upper stud  307  extends and a lower horizontal surface  313  from which the lower stud  309  extends.  
         [0042]     An upper fastener member  340 , typically a nut, and a lower fastener member  350 , typically a nut, secures the apparatus  210  together. The upper threaded stud  307  of the sensor  299  extends upward from the main body portion  301  through a bore in the upper horizontal portion  282  of the bracket  280  and a bore in the vehicle seat frame  220  to the upper fastener member  340 .  
         [0043]     The upper surface  311  of the main body portion  301  of the sensor  299  engages a lower surface  921  of the upper horizontal portion  282  of the bracket  280 . An upper surface  922  of the upper horizontal portion  282  of the bracket  280  engages a lower surface  221  of the vehicle seat frame  220 . An upper surface  222  of the vehicle seat frame  220  engages the upper fastener member  340 .  
         [0044]     The lower threaded stud  309  extends downward from the main body portion  301  simultaneously through a bore defined by the inner annular sleeve portion  322  of the bracket assembly  320  and a bore defined by the inner annular surface  266  of the resilient member assembly  260  to the lower fastener member  350 .  
         [0045]     The lower surface  313  of the main body portion  301  of the sensor  299  engages an upper surface  331  of the upper horizontal portion  326  of the upper bracket member  321 . A lower surface  333  of the upper horizontal portion  326  of the upper bracket member  321  engages the upper surface  263  of the resilient member assembly  260 . The lower surface  264  of the resilient member assembly  260  engages an upper surface  335  of the lower horizontal portion  327  of the lower bracket member  322 . A lower surface  337  of the lower horizontal portion  327  of the lower bracket member  322  engages the lower fastener member  350 .  
         [0046]     The two fasteners  340 ,  350  together secure the resilient member assembly  260  in a compressed condition. Thus, part of the resilient member assembly  260  compresses and part of the resilient member assembly expands when a vertical load is placed on the vehicle seat frame  20 .  
         [0047]     When a downward load is placed on the seat frame  220 , the portion  701  of the upper resilient member  261  between the lower surface  333  of the upper horizontal portion  326  of the upper bracket member  321  and the upper surface  252  of the upper portion  250  of the bracket  230  compresses while the sensor  299  senses the downward load. As stated above, the portion  701  of the upper resilient member  261  mitigates any downward dynamic load, or spike, that may be imparted to the apparatus  210  during a collision or other such condition.  
         [0048]     When an upward load is placed on the seat frame  220 , the portion  703  of the lower resilient member  262  between the lower surface  254  of the upper portion  250  of the bracket  230  and the upper surface  335  of the lower horizontal portion  327  of the bracket member  322  compresses while the sensor  299  senses the upward load. As stated above, the portion  703  of the lower resilient member  262  mitigates any downward dynamic load, or spike, that may be imparted to the apparatus  210  during a collision or other such condition.  
         [0049]     In either apparatus  10  or  210 , any initial stresses incurred by the sensor due to initial loading by manufacturing tolerances or assembly tolerances (i.e., tightening of the fastener members, etc.) may be factored out during an initial calibration of the sensor.  
         [0050]     The sensor produces an output signal directly proportional to the vertical force applied to the seat frame via the vehicle seat (i.e., the weight of the vehicle occupant, a load incurred during a vehicle collision, etc.). The sensor, while preferably the sensor  99  or  299  described above, may be any comparable sensor.  
         [0051]     Either apparatus  10  or  210  may be placed at a corner of a rectangular seat frame and may be used in conjunction with other similar apparatuses to generate multiple signals (such as two at the front corners of a seat frame and two at rear corners of a seat frame in  FIG. 1 ). A wire harness  390  may transmit the output signals from the apparatuses to an electrical controller  400 .  
         [0052]     The sensor  10  or  210  may be electrically connected to the controller by lead wires running to the connector plugs  103  or  303  mounted on the sensor. The controller  400  processes the signals from the apparatuses at each corner of the seat and generates an output signal indicative of the load on the seat frame. The multiple signals also can be analyzed by the controller  400  to produce output signals for controlling occupant protection devices, such as an air bags, seat belt pretensioners, etc.  
         [0053]     A seat belt assembly (not shown) may also be associated with the vehicle seat. The seat belt assembly would include a seat belt retractor, mounted for example to the vehicle floor pan, and a seat belt buckle connected to the bracket. The seat belt would extend from the retractor to the buckle across a vehicle occupant in the seat.  
         [0054]     From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications. For example, the apparatus  10  or  210  may be placed below the upper and lower tracks with the bracket attaching directly to the vehicle floor pan. Such improvements, changes and modifications are intended to be included within the scope of the appended claims.