Abstract:
A buckle switch arrangement for a multi-point seat belt system. A restraints control module is provided to receive signals from sensors operatively associated with the vehicle seat which determine and identify seat occupancy and also to receive signals from other sensors operatively associated with the vehicle seat which sense seat belt webbing payout. The signals obtained by the restraints control module are interpreted and, based on the interpretation, a telltale device may be activated to warn the vehicle operator that a seat occupant is not in compliance with seat belt usage.

Description:
TECHNICAL FIELD 
       [0001]    A buckle switch arrangement for seat belts is provided. The arrangement includes a device in the nature of a Hall effect sensor coupled with the seat belt retractor for sensing the amount of seat belt extracted. Information regarding the belt payout is relayed to a module to determine if the belt is being worn properly and may also determine if a telltale indicating non-compliance of seat belt usage or incorrect seat belt usage should be illuminated. 
       BACKGROUND OF THE INVENTION 
       [0002]    Automotive vehicles incorporate a variety of restraint systems to provide for the safety of occupants. For example, it is known in the vehicle art to provide various types of seat belts or restraint systems for restraining an occupant in his or her seat and for providing controlled deceleration of the occupant from an event such as a collision. Various types of seat belts and restraint systems have been used in automobiles, trucks, and other vehicles and are commonly known today. 
         [0003]    Known seat belt systems typically used in commercially available production vehicles include a seat belt telltale that is visible to the driver. The seat belt telltale is illuminated in the event that a seat belt is not being used in 3-point seat belt systems for some time. 
         [0004]    A commonly used telltale arrangement includes an electrical switch in the buckle that senses engagement between the tongue or latchplate and the buckle. This arrangement identifies the buckle status and, hence, seat belt usage. Non-compliance with seat belt usage results in a signal light being illuminated on or near the instrument cluster. This signaling is initiated when associated electrical information (e.g., voltage) is transmitted using a wiring harness attached to the buckle assembly and subsequently used (e.g., by a Restraints Control Module [an “RCM”]) to determine if the telltale should be illuminated. Examples of buckle switch systems may be found in U.S. Pat. Nos. 4,060,878, 4,163,128, 4,920,629, and 6,381,815. 
         [0005]    An alternate method for sensing seat belt use compliance is an arrangement that is used to determine if the amount of extraction of webbing from the seat belt retractor is greater than a minimum amount that would indicate seat belt usage. This is commonly done using a mechanical device in the retractor which determines the number of revolutions of the retractor spool and hence the amount of webbing extracted. An example of this arrangement may be found in U.S. Pat. No. 4,866,223. 
         [0006]    While the above-cited references provide certain advancement in the state of the art of systems for detecting and relaying information relative to seat belt use compliance, opportunities for improving such systems yet exist. 
       BRIEF DESCRIPTION 
       [0007]    The disclosed embodiments of the invention are generally directed to a buckle switch arrangement for a multi-point seat belt system. The embodiments are all directed to a system that determines and relays the status of seat belt usage. The present invention finds particular application with a four-point seat belt system but could also be used with any multi-point seat belt system using one or more retractors. The arrangement includes an occupant seat in a vehicle, a seat belt arrangement operatively associated with the seat, at least one seat belt retractor with which at least one seat belt of the seat belt arrangement is operatively associated, and a feedback sensor associated with the seat belt retractor. The system further includes a seat occupancy sensor which senses occupancy of the seat. A restraints control module is provided to receive signals from the feedback sensor and from the occupancy sensor. The signals obtained by the restraints control module are interpreted by algorithmic analysis and, based on the interpretation, a telltale device may be activated to warn the vehicle operator that a seat occupant is not in compliance with seat belt usage or is using the seat belt incorrectly. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    For a more complete understanding of this invention, reference should now be made to the embodiment illustrated in greater detail in the accompanying drawings and described below by way of examples of the invention wherein: 
           [0009]      FIG. 1  illustrates a stylized view of the intelligent arrangement buckle switch for seat belts as set forth herein; and 
           [0010]      FIG. 2  is an algorithm which accompanies the arrangement of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0011]    In the following figures, the same reference numerals will be used to refer to the same components. In the following description, various operating parameters and components are described for one constructed embodiment. These specific parameters and components are included as examples and are not meant to be limiting. 
         [0012]    Referring to the drawings and in particular to  FIG. 1 , one embodiment of a four-point seat belt restraint system, generally illustrated as  10 , is shown in the donned position. A seat  12 , typically for use in an automotive vehicle (not shown), includes a generally upright seat back  14  extending between a top portion  16  and a bottom portion  18  for supporting the back of a seated occupant. The seat  12  further includes a generally horizontal seat cushion  20  projecting forwardly from the bottom portion  18  of the seat back  14  and extending between an inboard or right side  22  and an outboard or left side  24  for supporting the bottom of the seated occupant. The inboard, side  22  is further defined by the side of the seat  12  adjacent the inboard or middle of the vehicle and the outboard side  24  is further defined by the side of the seat  12  adjacent the outboard or outside of the vehicle as is commonly known in the art. 
         [0013]    The four-point seat belt restraint system  10  includes a first, or inboard shoulder belt webbing  26  extending from the top portion  16  to the bottom portion  18  of the seat back  14  adjacent the inboard side  22  of the seat cushion  20 . The four-point seat restraint system  10  further includes a second, or outboard, shoulder belt webbing  28  extending from the top portion  16  to the bottom portion  18  of the seat back  14  adjacent the outboard side  24  of the seat cushion  20 . The four-point seat belt restraint system  10  further includes a first, or inboard, lap belt webbing  30  extending from the inboard side  22  of the seat cushion  20  to a buckle/tongue  32  (which may be either a tongue or a buckle) and a second, or outboard, lap belt webbing  34  extending from the outboard side  24  of the seat cushion  20  to a tongue/buckle  36  (which may be either a buckle or a tongue). The first lap belt webbing  30  is anchored to the seat  12  by a retractor  38  having a retractor spool  39 . The retractor  38  is anchored to the seat by fasteners including bolts, welds and the like. The second lap belt webbing  34  is anchored to the seat  12  by a retractor  40 , also attached to the seat  12  by the mentioned fasteners. The retractor  40  includes a spool  41 . When the first shoulder belt webbing  26 , the second shoulder belt webbing  28 , the first lap belt webbing  30 , and the second lap belt webbing  34  are donned and the buckle/tongue  32  and the tongue/buckle  36  are attached, the assembled buckle/tongue  32  and tongue/buckle  36  are ideally located across the centerline of the occupant (not shown). 
         [0014]    In particular, the lap belt retractors  38  and  40  (as well as the shoulder belt retractors) may even be attached to the body structure in so-called body mounted systems. The present invention easily extends such a body mounted system if additionally a sensor  43  may be provided to measure fore and aft seat travel (if the seat is movable). This information is processed together with the lap retractor webbing information to determine occupant presence and the like. 
         [0015]    The retractors  38  and  40  may be positioned in a variety of places relative to the seat  12 , but are shown herein in their preferred positions substantially under the seat  12 . The illustrated under-seat location of the lap belt retractors  38  and  40  under the seat makes packaging of the retractors easier and more economical, particularly in vehicles where seat-to-tunnel or seat-to-door spacing is restricted. 
         [0016]    While two retractors  38  and  40  are illustrated it is to be understood that a single retractor may be used in lieu of the shown and discussed pair. Conversely, the retractors  38  and  40  may be substituted for by a rigid, fixed anchor as is known in the art. The retractors  38  and  40  may be of a variety of types, including mechanical, mechanical with electric retractor, electromagnetic, and others. An electric retractor is valuable in that it offers a selected tension (either constant or varying) to be imposed on the lap belts  30  and  34  to aid in maintaining the buckle/tongue  32  and the tongue/buckle  36  as low on the occupant&#39;s lap as possible. In addition, a high lap belt tension also resists lateral motion of the lap belts  30  and  34 , thereby assisting in maintaining the buckle-tongue interface of the buckle/tongue  32  and the tongue/buckle  34  as close to the centerline of the occupant as is possible. This arrangement offers an improvement over known restraint systems using conventional mechanical retractors. The retractors  38  and  40  may also be equipped with dynamic pretensioners (of the pyrotechnic type or of another design). The retractors  38  and  40  also may be equipped with static; pretensioning. 
         [0017]    The first shoulder belt webbing  26  is releasably attachable to the buckle/tongue  32  and the second shoulder belt webbing  28  is releasably attachable to the tongue/buckle  36 . The buckle/tongue  32  is releasably attachable to the tongue/buckle  36 . This arrangement results in the illustrated V-shape defined by the substantial convergence of the first shoulder belt webbing  26  and the second shoulder belt webbing  28  at the buckle/tongue  32  and the tongue/buckle  36 . The first shoulder belt webbing  26  and the second shoulder belt webbing  28  have a large lateral spacing as illustrated from the occupants neck (not shown) while still providing effective support by the convergence along the centerline of the occupant at the area of the buckle/tongue  32  and the tongue/buckle  36 . This increased lateral spacing at the upper part of the seat  12  increases occupant comfort for occupants of different sizes, including smaller occupants having smaller necks, narrower shoulders and shorter upper torso eights. This geometry also aids in keeping seat belts on the occupant&#39;s shoulders at all times, while lowering the risk of soft tissue neck injury and enhancing comfort for wide range of occupant builds. 
         [0018]    It is to be understood that the buckle arrangement illustrated in  FIG. 1  may be altered so that, for example, the buckle component is provided on the shoulder webbing. The configuration shown is intended as being illustrative and not limiting. 
         [0019]    The first shoulder belt webbing  26  and the second shoulder belt webbing may be anchored to the seat  12  by separate or a single retractor (neither shown) fixedly secured to the seat  12  by fasteners including bolts, welds and the like. Alternatively, the retractor may be mounted on the body as in known body-mounted systems. 
         [0020]    The restraint system  10  is fitted with an occupant sensing and identification system for determining whether or not the seat  12  is occupied. The occupant sensing and identification system also functions to determine whether the occupant is a child in a Child Restraint Seat (CRS). The occupant sensing and identification system includes a first of two occupant sensing and identification sensors  42  operatively associated with the seat  10 . The occupant sensing and identification system further includes a second of two occupant sensing and identification sensors  44  also operatively associated with the seat  10 . When activated, the first occupant sensing and identification sensor  42  and the second occupant sensing and identification sensor  44  provide an electrical signal to an Occupant Classification System (OCS) unit  46  via a first conduit  48  connected between the first occupant sensing and identification sensor  42  and the OCS unit  46  and via a second conduit  50  connected between the second occupant sensing and identification sensor  44  and the OCS unit  46 . The OCS unit  46  then analyzes the received electrical signal and, if appropriate, sends a corresponding electrical input signal of a sufficient and pre-established value to a Restraints Control Module  52  which interprets the information received from the OCS unit  46  and generates, if appropriate, an electrical signal to a telltale device  54  as will be discussed in greater detail below. The telltale device  54  may produce a visual signal, an audio signal, or both. 
         [0021]    The restraint system  10  is further fitted with a sensor arrangement to determine if the webbing of the retractors  38  and  40  have been paid out. Particularly, a payout sensor  56 , such as an electromagnetic e.g., optical or electrical, mechanical or even possibly chemical sensor, is fitted to the retractor  38 . A similar or same payout sensor  58  is fitted to the retractor  40 . The sensors  56  and  58  monitor the webbing payout from each of the retractors  38  and  40 , respectively. Electrical input signals (for example, current in mA) are sent to the Restrains Control Module (RCM)  52  by way of a first electrical conduit  60  and a second electrical conduit  62 , the first electrical conduit  60  being associated with the retractor  38  and the second electrical conduit  62  being associated with the retractor  40 . The RCM  52  then interprets the information received from the payout sensors  56  and  58 . Once the information is interpreted, the RCM  52  generates, if appropriate, an electrical signal to a telltale device  54 . 
         [0022]    The RCM  52  uses an algorithm to determine whether or not the telltale device  54  should be activated. While a number of related algorithms may be used to determine the nature of the seat belt usage, a preferred algorithm to effect this purpose is set forth in  FIG. 2 . According to this algorithm, the initial inquiry is whether or not the ignition of the vehicle is on. If the ignition is not on, then no signal is sent to the telltale device  54 . If the ignition is on, then an inquiry is made whether or not an occupant is present, as sensed by the sensors  56  and  58  and as interpreted by the OCS  46 . In the event that it is determined that no occupant is present, then no signal will be sent to the telltale device  54 . 
         [0023]    Is an occupant present? If it is determined that an occupant is present in the seat, then two inquiries are made, both with respect to whether or not the lap belt webbing has been extracted far enough from the retractor to confirm proper seat belt utilization. 
         [0024]    Is the occupant an adult or a child? If the determination is “yes” then two further inquires will be made. One inquiry is whether or not a child restraint seat (CRS) is present with a child seated therein. If the answer is “yes,” then no signal will be sent to the telltale device  54 . If, however, the answer is “no” (indicating that a child restraint seat is present but the seat is unrestrained), then an activation signal will be sent to the telltale device  54 . 
         [0025]    The other inquiry is whether or not the webbing from the lap belt retractor has been withdrawn far enough to confirm that the seat belt is, in fact, being properly used. If the answer to this is “yes” and if the difference in the length of belt webbing exhausted from each retractor is less than or equal to a predetermined amount (for example, 2.0″), then no signal will be generated. If, on the other hand, the answer to the first question is “yes” and the difference in extracted belt webbing is greater than the predetermined amount, then a signal will be generated. 
         [0026]    If, however, the answer to the original inquiry (regarding the sufficiency of webbing length extracted from the lap belt retractor) is “no,” then an activation signal will be sent to the telltale device  54 . 
         [0027]    The possible conditions (other than the ignition being “off”) are summarized in Table 1. The algorithm is used to determine the following classifications: 
         [0028]    (1) no occupant 
         [0029]    (2) occupant (not in CRS) buckled, with buckle in proper position (correct zone) 
         [0030]    (3) occupant (not in CRS) buckled, with buckle out of zone 
         [0031]    (4) occupant (not in CRS) not buckled 
         [0032]    (5) occupant in restrained CRS 
         [0033]    (6) occupant in unrestrained CRS 
         [0034]    In the event that conditions (3), (4), or (6) exist, the RCM  52  will send an activating signal to the telltale device  54 . In the event that conditions (1), (2) or (5) are determined to exist, no such signal will be sent. 
         [0000]    
       
         
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                   
                   
                 Child 
                   
                   
               
               
                   
                   
                   
                   
                 seat (with 
               
               
                   
                   
                   
                   
                 child)? 
                 Buckle 
               
               
                   
                   
                 Occupant? 
                 Seatbelt 
                 (sensed 
                 within 
               
               
                 Condition 
                 Description 
                 (sensed by OCS) 
                 “buckled”? 
                 by OCS) 
                 zone? 
                 Telltale 
               
               
                   
               
             
             
               
                 1 
                 No occupant 
                 N 
                 Y/N 
                 N 
                 Y/N 
                 Off 
               
               
                 2 
                 Occupant 
                 Y 
                 Y 
                 N 
                 Y 
                 Off 
               
               
                   
                 (not in CRS) 
               
               
                   
                 buckled, with 
               
               
                   
                 buckle in 
               
               
                   
                 zone 
               
               
                 3 
                 Occupant 
                 Y 
                 Y 
                 N 
                 N 
                 On 
               
               
                   
                 (not in CRS) 
               
               
                   
                 buckled, with 
               
               
                   
                 buckle out of 
               
               
                   
                 zone 
               
               
                 4 
                 Occupant 
                 Y 
                 N 
                 N 
                 N/A 
                 On 
               
               
                   
                 (not in CRS) 
               
               
                   
                 not buckled 
               
               
                 5 
                 Occupant in 
                 Y 
                 Y 
                 Y 
                 Y/N 
                 Off 
               
               
                   
                 restrained 
               
               
                   
                 CRS 
               
               
                 6 
                 Occupant in 
                 Y 
                 N 
                 Y 
                 N/A 
                 On 
               
               
                   
                 unrestrained 
               
               
                   
                 CRS 
               
               
                 7 
                 Occupant in 
                 Y 
                 N 
                 Y 
                 N/A 
                 On 
               
               
                   
                 booster 
               
               
                 8 
                 Occupant in 
                 Y 
                 Y 
                 Y 
                 N 
                 On 
               
               
                   
                 booster 
               
               
                 9 
                 Occupant in 
                 Y 
                 Y 
                 Y 
                 Y 
                 Off 
               
               
                   
                 booster 
               
               
                   
               
               
                 NOTE 1: 
               
               
                 Above assumes “Ignition On”. For the trivial case, of “Ignition Off” the telltale will be “OFF” 
               
               
                 NOTE 2: 
               
               
                 Above also assumes that if webbing &gt;L crit  is pulled out of either retractor =&gt; “buckled” state. 
               
               
                 NOTE: 3: 
               
               
                 “Null” signal treated as “No” 
               
               
                 NOTE 4: 
               
               
                 Assume whenever a CRS is present, it is restrained by the seatbelt system. Hence a typical booster seat would not be treated as a CRS by this algorithm. 
               
             
          
         
       
     
         [0035]    According to the present invention, a solution to known problems associated with non-compliance with seat belt usage requirements is presented in an efficient and cost-effective manner. The vehicle operator will immediately know if a passenger is not wearing a seatbelt or if a passenger is wearing a seat belt but the seat belt buckle is outside of the preferred zone for effective wearing. The present invention also provides information to the vehicle operator as to whether or not a child is in an unrestrained child restraint seat.