Patent Publication Number: US-6708380-B2

Title: Breakaway latch plate

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a latch plate for a seat belt system. More specifically, the present invention relates to a breakaway latch plate that maintains seat belt webbing at a fixed position relative to the plate during normal usage, but allows movement of the seat belt webbing in accident conditions. 
     2. Technical Background 
     Seat belts are known to increase the safety of occupants in various motorized vehicles. Seat belt use is often cited as the most useful line of defense in reducing accident related injuries. The actions of consumer groups, governmental agencies, and political activists all reflect the tremendous societal value of seat belt use. Legislation requiring manufacturers to include seat belts in their vehicles has been in place for many years. More recently, laws have been enacted requiring consumers to use seat belts. 
     The benefits of seat belt use are numerous. In a collision, seat belts may prevent the occupant of a vehicle from striking the interior of the vehicle or other objects within the vehicle, including other occupants. Seat belts aid in keeping the occupant inside the vehicle, where the chances of survival are much greater. Seat belts may also keep the driver behind the wheel and in control of the vehicle in a collision, averting additional damage or injuries. Seat belts also enhance the effectiveness of other safety devices. For example, in a vehicle with airbags, a seat belt keeps the occupant in the seat, so the airbag can better protect the occupant. 
     Statistics show that lap and shoulder belts, when used properly, reduce the risk of fatal injury in front-seat occupants of cars by 45 percent and the risk of moderate-to-critical injury by 50 percent. With respect to light truck occupants, seat belts reduce the risk of fatal injury by 60 percent and moderate-to-critical injury by 65 percent. 
     Seat belts vary in their configuration, but one of the most common types of seat belts is the lap belt. The lap belt includes right and left belts, which traverse an occupant&#39;s lap and are secured to each other by a buckle, which is often located near the occupant&#39;s mid-abdomen. Lap belts are found in many different types of vehicles throughout the world. 
     Although conventional lap belts are well used and accepted, they do not limit movement of an occupant&#39;s head and torso. Thus, although the lower body is restrained, the upper body may experience rapid and dangerous movement during an accident. This is particularly dangerous for passengers in the front seat of an automobile, who may strike the steering wheel, dashboard, or windshield during an accident. 
     A seat belt having a shoulder strap limits an occupant&#39;s upper body movement in an accident, providing improved and potentially lifesaving restraint. Shoulder-strap restraints come in various configurations, involving both single- and double-strap implementations. In one commonly employed shoulder-strap configuration, the seat belt webbing traverses the occupant&#39;s upper body in a diagonal fashion, passes through a latch plate, and then traverses the occupant&#39;s lap. The latch plate is fastened to a buckle, which is secured to the vehicle. This seat belt system is frequently employed in passenger vehicles and is frequently referred to as a three-point seat belt system. 
     However, in this configuration, problems arise in loading and unloading occupants. Often the latch plate becomes dislocated from its correct position, making it difficult for the occupant to locate the latch plate or correctly position the latch plate before engaging the seat belt. 
     Dislocation of the latch plate creates a number of safety and convenience issues. For example, the latch plate could move so far from its correct position that it may be difficult for the occupant to locate or secure the latch plate, discouraging the occupant from using the seat belt. Also, in this condition, the seat belt webbing is more likely to become knotted or entangled with other items around the seat belt. Further, if the latch plate is not in the correct position when in use, the seat belt webbing may have slack, preventing the seat belt from safely restraining the occupant during an accident. 
     Locking the latch plate into a fixed position relative to the seat belt webbing is one potential solution to the problems noted above. However, this solution has substantial limitations in certain scenarios. In a collision, the torso of the occupant is often thrust forward, applying great pressure to the torso portion of the seat belt webbing (the portion of the seat belt webbing above the latch plate). If the latch plate is locked into position relative to the seat belt webbing, the tension in the torso portion of the seat belt webbing will not be transferred to the lap portion of the seat belt webbing (the portion of the seat belt webbing below the latch plate). As a consequence, the lap portion of the seat belt webbing may be undesirably loose. 
     In this condition, the occupant&#39;s lower body may strike portions of the vehicle or other objects with great force. Most dangerously, lacking tension in the lap portion of the seat belt webbing, the occupant may slide completely or partially out of the seat belt restraint (a process known as “submarining”), resulting in potentially more serious injuries. The transfer of tension from the torso portion of the seat belt to the lap portion of the seat belt during an accident is desirable and enhances the restraining capabilities of the seat belt. 
     Thus, it would be an advancement in the art to provide a latch plate that maintains a fixed position relative to the seat belt webbing during normal usage, but enables movement of the seat belt webbing relative to the plate in the event of an accident. 
     Such a latch plate is disclosed and claimed herein. 
     SUMMARY OF THE INVENTION 
     The apparatus and methods of the present invention have been developed in response to the present state-of-the-art, and, in particular, in response to problems and needs in the art that have not yet been fully resolved by currently available inflatable seat belt systems. The present invention provides an apparatus for enhancing the effectiveness of seat belt systems. To achieve the foregoing, and in accordance with the invention as embodied and broadly described in the preferred embodiment, a breakaway latch plate is disclosed that maintains seat belt webbing at a fixed position relative to the plate during normal usage, but allows movement of the seat belt webbing relative to the latch plate during accident conditions. 
     In one embodiment, the breakaway latch plate may be used in connection with a three-point seat belt system. A three-point seat belt system may include seat belt webbing connected at one end to a torso retractor and at the other end to lap retractor. 
     The breakaway latch plate, which is coupled to the seat belt webbing, includes a latch plate body. More specifically, an interior surface of the latch plate body defines an orifice through which the seat belt webbing passes. The latch plate body includes a buckle interface that may interface with and be inserted into a buckle to secure the seat belt webbing across an occupant of the vehicle. When the buckle interface is secured to the buckle, a torso portion of the seat belt webbing diagonally traverses the occupant&#39;s body, while a lap portion of the seat belt webbing crosses the occupant&#39;s lap. 
     A locking mechanism is coupled to the latch plate body. The locking mechanism prevents movement of the seat belt webbing relative to the latch plate body when the locking mechanism is in a locked state. Conversely, when the locking mechanism is in an unlocked state, the locking mechanism permits movement of the seat belt webbing relative to the latch plate body. 
     The locking mechanism changes from the locked to the unlocked state in response to at least a predetermined load being applied to the seat belt webbing, such as during accident conditions. As a consequence, during an accident, tension in the torso portion of the seat belt webbing may be transferred to the lap portion of the seat belt webbing to provide additional restraint to an occupant&#39;s legs and lower body. 
     The predetermined load required to change the breakaway latch plate from the locked to the unlocked state may be set by a manufacturer of the latch plate through, for instance, selection of materials of a particular strength to make the locking mechanism. Also, variations in the design of the locking mechanism contribute to setting the predetermined load required to change the plate into an unlocked state. 
     The locking mechanism may be embodied in various forms, four of which are disclosed herein. The disclosed embodiments are, of course, merely illustrative, not limiting of the scope of this invention. 
     The first embodiment includes a cam having a guide track, a pin opening, and a movable gripping mechanism. A guide pin, which is also attached the latch plate body, is disposed within the guide track. The guide track may be embodied in various forms, following both linear and nonlinear paths. In one embodiment, the guide track is sized just large enough to receive the guide pin, but to not permit the guide pin to move within the track. 
     A breakaway pin, which is attached to the latch plate body, is disposed within the pin opening. The breakaway pin is designed to break upon the application of at least a predetermined force to the pin. 
     The movable gripping mechanism (e.g., teeth) of the cam contacts and grips the seat belt webbing passing through the orifice when the locking mechanism is in a locked state. When a load is applied to the seat belt webbing, force is applied to the moveable gripping mechanism and cam. Consequently, force is applied to the breakaway pin. When the load is equal to or exceeds a predetermined load set by the manufacturer of the breakaway latch plate, the breakaway pin breaks and the cam (along with the movable gripping mechanism) rotates away from the seat belt webbing about the guide pin, permitting the seat belt webbing to move relative to the latch plate body. 
     In a second embodiment of the breakaway latch plate, the locking mechanism includes a locking pin. The interior surface, which defines the orifice through which the seat belt webbing passes, further defines a retention notch within the orifice. An aperture is disposed within the seat belt webbing. 
     The locking pin is disposed through the aperture in the seat belt webbing when the locking mechanism is in a locked state. In the locked state, the locking pin is also disposed, at one end, within the retention notch. The other end of the locking pin is attached to a hinged cam. The hinged cam is rotatably connected to the latch plate body. 
     When a load is applied to the seat belt webbing, the edges of the aperture exert force on the locking pin. If the applied load is equal to or greater than a predetermined load, the locking pin deforms and is displaced from both the retention notch and the aperture, permitting movement of the seat belt webbing relative to the latch plate body. 
     In a third embodiment of the breakaway latch plate, a locking pin, which is frangible, includes a first and a second end. The interior surface defining the orifice also defines at least one retention notch for receiving the first and second ends of the locking pin. Again, an aperture is disposed in the seat belt webbing. 
     In a locked state, the locking pin is disposed through the aperture of the seat belt webbing, and the first and second ends of the locking pin are retained within the one or more retention notches. 
     When a load is applied to the seat belt webbing, the edges of the aperture in the webbing exert force on the locking pin. As stated above, the locking pin is frangible. Consequently, when at least a predetermined load is applied to the seat belt webbing, the locking pin breaks so that the seat belt webbing may move relative to the latch plate body. 
     The fourth embodiment of the locking mechanism is similar to the third embodiment. However, instead of the locking pin being frangible, the retention notches are frangible. As a consequence, in a locked state, the locking pin passes through the aperture and the first and second ends of the locking pin are disposed within at least one frangible retention notch. 
     Again, when a load is applied to the seat belt webbing, the seat belt webbing at the edges of the aperture applies force to the locking pin and consequently to the frangible retention notches. When the predetermined load is applied to the seat belt webbing, the notch, rather than the locking pin, breaks to permit the seat belt webbing to move relative to the latch plate body. 
     In view of the foregoing, the breakaway latch plate offers advantages not present in conventional latch plates. The breakaway latch plate retains a fixed position relative to the seat belt webbing during normal usage. Thus, the latch plate may be conveniently accessed and used by an occupant. However, in accident conditions, the seat belt webbing may move with respect to the latch plate body, permitting tension from the torso portion of the seat belt webbing to be transferred to the lap portion of the seat belt webbing and vice versa. 
     These and other advantages of the present invention will become more fully apparent from the following description and appended claims, or maybe learned by the practice of the invention as set forth hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In order that the manner in which the advantages and features of the invention are obtained, a more particular description of the invention summarized above will be rendered by reference to the appended drawings. Understanding that these drawings illustrate only selected embodiments of the invention and are not therefore to be considered limiting in scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
     FIG. 1 is a plan view of a three-point seat belt system including a breakaway latch plate; 
     FIG. 2 a  is a cross-sectional view of a first embodiment of the breakaway latch plate in a locked state; 
     FIG. 2 b  is a cross-sectional view of the first embodiment of the breakaway latch plate in an unlocked state; 
     FIG. 3 a  is a cross-sectional view of a second embodiment of the breakaway latch plate in a locked state; 
     FIG. 3 b  is a cross-sectional view of the second embodiment of the breakaway latch plate in an unlocked state; 
     FIG. 4 a  is a cross-sectional view of a third embodiment of the breakaway latch plate in a locked state; 
     FIG. 4 b  is a cross-sectional view of the third embodiment of the breakaway latch plate in an unlocked state; 
     FIG. 5 a  is a cross-sectional view of a fourth embodiment of the breakaway latch plate in a locked state; and 
     FIG. 5 b  is a cross-sectional view of the fourth embodiment of the breakaway latch plate in an unlocked state. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The preferred embodiments of the invention are now described with reference to FIGS. 1-5. The members of the present invention, as generally described and illustrated in the Figures, may be implemented in a wide variety of configurations. Thus, the following more detailed description of the embodiments of the system and method of the present invention, as represented in the Figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of presently preferred embodiments of the invention. 
     Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to convey a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention. 
     FIG. 1 is a plan view of a three-point seat belt system  10  including a breakaway latch plate  12 . Three-point seat belt systems  10  are well-known in the art and are frequently implemented in connection with passenger vehicles. 
     Seat belt webbing  14  used in connection with such a system  10  may have a first end  16  and a second end  18 . The first end  16  of the seat belt webbing  14  may be coupled to a torso retractor  20 , and the second end  18  may be coupled to a lap retractor  22 . Retractors  20 ,  22  are well-known in the art and serve to stop movement of the seat belt webbing  14  when a corresponding vehicle rapidly accelerates or decelerates or when seat belt webbing  14  is rapidly pulled from the retractor  20 ,  22 . 
     The breakaway latch plate  12 , which will be described in detail below, may be used in connection with both conventional, uninflatable seat belt webbing  14  and inflatable seat belt webbing  14 . Inflatable seat belt webbing  14  includes seat belt webbing  14  in which inflatable members  24  (similar to airbags) are disposed on or within the seat belt webbing  14 . If an inflatable member  24  is disposed within the seatbelt webbing  14 , the webbing  14  may include a frangible seam (not shown) that ruptures upon inflation of the member  24 . Inflatable members may be in fluid communication with an inflator (not shown) that transmits gas or other filler medium to the inflatable members in the event of an accident. 
     As stated above, FIG. 1 also illustrates a breakaway latch plate  12 . The breakaway latch plate  12  may include a latch plate body  26  having a buckle interface  28 . The buckle interface  28  interfaces with and may be inserted into a buckle  30 , which is attached to a corresponding vehicle, for securing the seat belt webbing  14  across an occupant  32  of the vehicle. 
     The breakaway latch plate  12  may include an interior surface  34  defining an orifice  36  through which the seat belt webbing  14  passes. The orifice  36  may be configured in various shapes and dimensions according to, for example, the dimensions of the seat belt webbing  14  passing through the orifice  36 . 
     A locking mechanism  38  may be coupled to the latch plate body  26 . The locking mechanism  38  may have a locked and an unlocked state. In the locked state, the locking mechanism  38  prevents movement of the seat belt webbing  14  relative to the latch plate body  26 . In the unlocked state, the locking mechanism  38  permits movement of the seat belt webbing  14  relative to the latch plate body  26 . 
     The locking mechanism  38  changes from the locked state to the unlocked state in response to at least a predetermined load being applied to the seat belt webbing  14 . For instance, in an accident, the torso  40  of the occupant  32  may be thrust forward, applying pressure to the torso portion  42  of the seat belt webbing  14  (the portion of the seat belt webbing  14  above the latch plate  12 ). If the pressure applied to the seat belt webbing  14  is greater than or equal to the predetermined load, the locking mechanism  38  changes to the unlocked state, permitting the tension from the torso portion  42  of the seat belt webbing  14  to be transferred to the lap portion  44  of the seat belt webbing  14  (the portion of the seat belt webbing  14  below the latch plate  12 ). The predetermined load required to change the locking mechanism  38  into the unlocked state may be specified by a particular manufacturer of the breakaway latch plate  12 . 
     The predetermined load required to change the breakaway latch plate  12  from the locked to the unlocked state may be determined by a manufacturer of the plate  12  through, for instance, selection of materials of a particular strength to make the plate  12 . Also, variations in the design of the breakaway latch plate  12  contribute to setting the predetermined load required to change the plate  12  into an unlocked state. 
     Various embodiments of the locking mechanism  38  are discussed in connection with FIGS. 2-5 below. Of course, the embodiments discussed below are illustrative and are not to be considered limiting of the scope of this invention. 
     FIG. 2 a  is a cross-sectional view of a first embodiment of the breakaway latch plate  46  in a locked state, while FIG. 2 b  illustrates the breakaway latch plate  46  in an unlocked state. A locking mechanism  48  is coupled to a latch plate body  50 , and the seat belt webbing  14  passes through an orifice  52 , which is defined by an interior surface  54  of the latch plate body  50 . As before, the locking mechanism  48 , in a locked state, prevents movement of the seat belt webbing  14  relative to the latch plate body  50  and, in an unlocked state, permits such movement. 
     In one embodiment, the locking mechanism  48  includes a cam  56 . As illustrated, the cam  56  is asymmetrically shaped. However, it should be noted that the cam  56  may be embodied in various symmetrical shapes, such as a circle. 
     The cam  56  may include a guide track  58 , which is shaped to receive a guide pin  60 . The guide pin  60  is attached to the latch plate body  50  and may be disposed within the guide track  58 . As illustrated, the guide track  58  follows a nonlinear course, although a guide track  58  with a linear course also comes within the scope of this invention. However, in other embodiments, the guide track  58  may be circular and sized to receive the guide pin  60 , allowing for rotation of the cam  56  about the guide pin  60  but not movement of the guide pin  60  within the guide track  58 . 
     The cam  56  may also include a pin opening  62 , which is shaped to receive a breakaway pin  64 . The breakaway pin  64  is attached to the latch plate body  50  and may be disposed within the pin opening  62 . The breakaway pin  64  is configured to break upon the application of at least a particular amount of force to the pin  64 , which corresponds to the predetermined load required to change the latch plate  50  into an unlocked state. 
     In addition, a movable gripping mechanism  66  may be disposed on the cam  56 . In the locked state, the movable gripping mechanism  66  contacts and grips the seat belt webbing  14  to prevent the seat belt webbing  14  from moving with respect to the latch plate body  50 . The movable gripping mechanism  66  may be embodied as teeth or another uneven surface that grips the seat belt webbing  14  and maintains the webbing  14  in a fixed position relative to the latch plate body  50  when the locking mechanism  48  is in a locked state. 
     The locking mechanism  48  may further include a fixed gripping mechanism  68  attached to the latch plate body  50  that contacts and grips the seat belt webbing  14  when the locking mechanism  48  is in a locked state. As with the movable locking mechanism  66 , the fixed locking mechanism  68  may be embodied as teeth or another uneven surface for gripping the seat belt webbing  14 . The fixed locking mechanism  68  aids the movable locking mechanism  66  in maintaining the seat belt webbing  14  in a fixed position relative to the latch plate body  50  when the locking mechanism  48  is in a locked state. 
     When a load is applied to the seat belt webbing  14 , force is applied to the gripping mechanism  66 , which is gripping the seat belt webbing  14 , and the cam  56 . That force is thus applied to the breakaway pin  64 . 
     As illustrated in FIG. 2 b , when a predetermined load is applied to the seat belt webbing  14 , the breakaway pin  64  breaks enabling the cam  56  to rotate about the guide pin  60  and separate the movable gripping mechanism  66  from the seat belt webbing  14 . The force of the seat belt webbing  14 , under the influence of the predetermined load, will push the movable locking mechanism  66  away from the seat belt webbing  14 . As such, the seat belt webbing  14  may move through the orifice  52 , unimpeded by the movable gripping mechanism  66 . 
     Referring to both FIGS. 2 a  and  2   b , in one embodiment, the movable gripping mechanism  66  comprises teeth inclined to limit movement of the seat belt webbing  14  through the orifice  52  toward the torso retractor  20 , and the fixed gripping mechanism  68  comprises teeth inclined to limit movement of the seat belt webbing  14  through the orifice  52  toward the lap retractor  22 , as illustrated in FIG. 2 a-b . As a consequence, in such an embodiment, only the application of the predetermined load to the torso portion  42  of the seat belt webbing  14  will displace the cam  56  and permit movement of the seat belt webbing  14  relative to the latch plate body  50 . 
     Of course, the teeth of the movable gripping mechanisms  66  could be inclined to limit movement of the seat belt webbing  14  toward the lap retractor  22 , and the teeth of the fixed gripping mechanism  68  could be inclined to limit movement of the seat belt webbing  14  toward the torso retractor  20  so that only application of the predetermined load to the lap portion  44  of the seat belt webbing  14  would displace the cam  56 . Also, it should be noted that uninclined teeth (teeth which are generally perpendicular to the seat belt webbing) also come within the scope of this invention. 
     Referring still to FIGS. 2 a  and  2   b , in one embodiment, frictional undulations  70  may be disposed on the cam  56 . The frictional undulations  70  contact the seat belt webbing  14  when the locking mechanism  48  is in an unlocked state. The undulations  70  may be embodied as illustrated in FIGS. 2 a  and  2   b  or may include another uneven surface that serves to moderate the speed with which the seat belt webbing  14  moves through the orifice  52  in the unlocked state. 
     In addition, the locking mechanism  48  may include a web guide  72 . The web guide  72  prevents the seat belt webbing  14  from contacting the movable gripping mechanism  66  when the locking mechanism is in an unlocked state. Without the web guide  70  the seat belt webbing  14  could contact the movable gripping mechanism  66 , undesirably limiting movement of the webbing  14 . 
     In an alternative embodiment, the guide pin  60  may also be frangible. In such an embodiment, when the predetermined load is applied to the seat belt webbing  14 , both the guide pin  60  and the breakaway pin  64  may break, enabling the movable gripping mechanism  66  to move away from the seat belt webbing  14 . 
     FIG. 3 a  is a cross-sectional view of a second embodiment of the breakaway latch plate  74  in a locked state, while FIG. 3 b  illustrates the breakaway latch plate  74  in an unlocked state. A locking mechanism  76  is coupled to the latch plate body  78 , and seat belt webbing  80  (inflatable or conventional seat belt webbing) passes through an orifice  82 , which is defined by an interior surface  84  of the latch plate body  78 . As before, a locking mechanism  76  prevents movement of the seat belt webbing  80  relative to the latch plate body  78  in a locked state and in an unlocked state, permits such movement. 
     The locking mechanism  76  includes a hinged cam  86 . The hinged cam  86  is rotatably connected to the latch plate body  78 . A locking pin  88 , which is deformable upon the application of at least a particular force, is disposed on the hinged cam  86 . The particular force required to deform the locking pin  88  corresponds to the predetermined load required to change the latch plate  74  into an unlocked state. 
     An aperture  90  is disposed within the seat belt webbing  80 . The aperture  90  may be sized to receive the locking pin  88 . Of course, the aperture  90  may be configured in various shapes, such as rectangular, square, or round. 
     A retention notch  92  is defined by the interior surface  84 , which also defines the orifice  82 . The retention notch  92  is shaped to receive and retain the locking pin  88  when the locking mechanism  76  is in a locked state, as shown in FIG. 3 a . The retention notch  92  may be configured in various ways, such as a recess defined by the surface  84 . Alternatively, the retention notch  92  may be formed by one or more surrounding protrusions defined by the surface  84 . 
     In the locked state, the locking pin  88  is disposed through the aperture  90  and retained within the retention notch  92 , as illustrated in FIG. 3 a . In the locked state, the locking mechanism  76  prevents movement of the seat belt webbing  80  relative to the latch plate body  78 . 
     When a load is applied to the seat belt webbing  80 , the seat belt webbing  80  at the edges  93  of the aperture  90  exerts force on the locking pin  88 . As illustrated in FIG. 3 b , when at least a predetermined load is applied to the seat belt webbing  80 , the force applied to the locking pin  88  deforms a locking pin  88  and displaces the pin  88  from within the aperture  90  and the retention notch  92 , as the hinged cam  86  rotates away from the seat belt webbing  80 . In this unlocked state, the seat belt webbing  80  may move with respect to the latch plate body  78 . 
     FIG. 4 a  is a cross-sectional view of a third embodiment of the breakaway latch plate  94  in a locked state, while FIG. 4 b  illustrates the breakaway latch plate  94  in an unlocked state. As before, the seat belt webbing  80  passes through an orifice  96 , which is defined by an interior surface  98  of a latch plate body  100 . Again, an aperture  90 , which may be configured in various shapes, is disposed within the seat belt webbing  80 . 
     A locking mechanism  102  retains the seat belt webbing  80  in a fixed position relative to the latch plate body  100  when in a locked state. In this embodiment, the locking mechanism  102  comprises a locking pin  104 . The locking pin  104  is frangible and breaks upon the application of at least a predetermined force. The predetermined force required to break the locking pin  104  corresponds to the predetermined load required to change the latch plate  94  into an unlocked state. 
     The locking pin  104  includes a first and a second end  106 ,  108 . The locking pin  104  may be configured in a variety of different shapes and sizes according to, for example, the desired force at which a manufacturer desires the locking pin  104  to break. 
     The interior surface  98 , which defines the orifice  96 , further defines at least one retention notch  110  within the orifice  96 . The retention notch or notches  110  are shaped and positioned to retain the first and second ends  106 ,  108  of the locking pin  104  when the locking mechanism  102  is in a locked state, as illustrated in FIG. 4 a.    
     The retention notch or notches  110  may be configured in a number of different ways within the scope of this invention. For instance, a single retention notch  110  may be disposed around the interior surface  98 , or at least a portion of the interior surface  98 , of the orifice  96  for receiving both the first and second ends  106 ,  108  of the locking pin  104 . Alternatively, for example, two or more discrete retention notches  110  may be disposed on opposing sides of the orifice  96 . Again, the retention notch  110  may be defined by a recess in the orifice  96  (as illustrated in FIG. 4 a ) or by protrusions disposed on the orifice  96 . 
     In the locked state, the locking pin  104  is disposed through the aperture  90  of the seat belt webbing  80  and the first and second ends  106 ,  108  of the locking pin  104  are retained within the retention notch or notches  110 , as illustrated in FIG. 4 a . When at least a predetermined load is applied to the seat belt webbing  80 , the pressure applied by seat belt webbing  80  at the edges  93  of the aperture  90  to the locking pin  104  breaks the locking pin  104 , as shown in FIG. 4 b . Consequently, in the unlocked state, the seat belt webbing  80  may move relative to the latch plate body  100  and tension from the torso portion  114  of the seat belt webbing  80  (the portion of the seat belt webbing above the latch plate) may be transferred to the lap portion  116  of the seat belt webbing  80  (the portion of the seat belt webbing below the latch plate) or vice versa. 
     In an alternative embodiment, either one or both of the first and second ends  106 ,  108  of the locking pin  104  are attached to the surface  98  defining the orifice  96 . Also, either the first or second ends  106 ,  108  of the locking pin  104  may be disposed within a retention notch  110 , while the other end  106 ,  108  is attached to the surface  98  defining the orifice  96 . 
     FIG. 5 a  is a cross-sectional view of a fourth embodiment of the breakaway latch plate  118  in a locked state, while FIG. 5 b  illustrates the breakaway latch plate  118  in an unlocked state. As before, the seat belt webbing  80  passes through an orifice  120 , which is defined by an interior surface  122  of the latch plate body  124 . Again, an aperture  90 , which may be configured in various shapes, is disposed within the seat belt webbing  80 . 
     Once again, a locking mechanism  126  retains the seat belt webbing  80  in a fixed position relative to the latch plate body  124  when in a locked state. In this embodiment, the locking mechanism  126  comprises a locking pin  128 . The locking pin  128  includes a first and a second ends  130 ,  132  and maybe configured in various shapes and sizes, as stated above. In this embodiment, however, the locking pin  128  is not designed to break. 
     The interior surface  122 , which defines the orifice  120 , further defines at least one frangible retention notch  134  within the orifice  120 . The frangible retention notch or notches  134  may be similar in shape and position to the retention notch or notches  110  disclosed in connection with the FIGS. 4 a-b . The frangible notch or notches  134  are likewise configured to receive and retain the first and second ends  130 ,  132  of the locking pin  128 . However, the frangible retention notch  134  is configured to break upon the application of the least a predetermined force. The predetermined force required to break the frangible retention notch  134  corresponds to the predetermined load required to change the latch plate  118  into an unlocked state. 
     Thus, in the locked state, the locking pin  128  is disposed through the aperture  90  and the first and the second ends  130 ,  132  of the locking pin  128  are retained within the frangible retention notch or notches  134 , as illustrated in FIG. 5 a . When a load is applied to the seat belt webbing  80 , the seat belt webbing  80 , at the edges  93  of the aperture  90 , applies force to the locking pin  128 , which, in turn, exerts force on the frangible notch or notches  134 . When at least the predetermined load is applied to the seat belt webbing  80 , the frangible notch  134  breaks to permit movement of the seat belt webbing  80  relative to the latch plate body  124 , as illustrated in FIG. 5 b.    
     In view of the foregoing, the breakaway latch plate  12 ,  46 ,  74 ,  94 ,  118  offers advantages not present in conventional latch plates. The breakaway latch plate  12 ,  46 ,  74 ,  94 ,  118  retains a fixed position relative to the seat belt webbing  14 ,  80  during normal usage. Thus, the latch plate  12 ,  46 ,  74 ,  94 ,  118  may be conveniently accessed and used by an occupant. However, in accident conditions, the latch plate  12 ,  46 ,  74 ,  94 ,  118  is movable with respect to the seat belt webbing  14 ,  80 , permitting tension from the torso portion  42 ,  114  of the seat belt webbing  14 ,  80  to be transferred to the lap portion  44 ,  116  of the seat belt webbing  14 ,  80  and vice versa. 
     In view of the foregoing, present invention may be embodied in other specific forms without departing from its scope or essential characteristics. The described embodiments are to be considered in all respects only illustrative, not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.