Abstract:
A latch system for vehicle doors includes a bypass mechanism that mechanically disconnects a linkage assembly if an exterior door handle is moved towards an open position at a high speed. The bypass mechanism ensures that the door latch mechanism does not unlatch in the event a crash causes the exterior door handle to move open at a high speed, while providing for normal unlatching operation if the exterior door handle is opened at a relatively low velocity by a user.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to a door latch system for motor vehicles, and specifically to a door latch that does not release if the exterior door handle is moved open at a high speed. 
       BACKGROUND OF THE INVENTION 
       [0002]    Various types of vehicle door latches and handles have been developed. The latch and handle assembly may include a handle that can be pulled outwardly by a user to release a door latch, thereby permitting the door to open. However, if a vehicle is subject to lateral acceleration due to a side impact such as a crash, the acceleration may cause the handle to shift outwardly due to its own mass, thereby causing the latch to release. Various counterweights and inertia locks have been developed to prevent inadvertent unlatching of a door latch during lateral acceleration of the vehicle. 
       SUMMARY OF THE INVENTION 
       [0003]    One aspect of the present invention is a latch system for vehicle doors including a movable door handle and a door latch mechanism having latched and unlatched configurations. A first linkage is connected to the door handle such that movement of the door handle moves the first linkage. A second linkage is connected to the door latch mechanism such that movement of the second linkage causes the latch mechanism to shift from the latched configuration to the unlatched configuration. The latch system further includes a bypass mechanism having an engaged configuration in which the bypass mechanism interconnects the first and second linkages such that movement of the first linkage causes movement of the second linkage to thereby unlatch the latch mechanism. The bypass mechanism disconnects the first and second linkages when the bypass mechanism is in a bypassed configuration such that movement of the first linkage does not cause movement of the second linkage to unlatch the latch mechanism. The bypass mechanism further defines a home configuration. When the bypass mechanism is in its home configuration, movement of the first linkage at a first velocity relative to the second linkage causes the bypass mechanism to shift from its home configuration to its engaged configuration. When the bypass mechanism is in its home configuration, movement of the first linkage relative to the second linkage at a second velocity that is significantly greater than the first velocity causes the bypass mechanism to shift from its home configuration to its bypass configuration such that movement of the first linkage at the second velocity does not unlatch the latch mechanism. The bypass mechanism includes a locking member that is connected to a selected one of the first and second linkages. The locking member includes a first engagement surface and a retaining surface. The bypass mechanism further includes a lever support that is connected to the other of the first and second linkages. The bypass mechanism still further includes a lever that is movably connected to the lever support. The lever includes a second engagement surface that is configured to engage the first engagement surface, whereby the lever interconnects the lever support and the locking member when the bypass mechanism is in its engaged configuration. The lever engages the retaining surface when the bypass mechanism is in its home configuration to prevent the second engagement surface from engaging the first engagement surface. The lever support is disconnected from the locking member when the bypass mechanism is in its bypassed configuration. 
         [0004]    Another aspect of the present invention is a latch system for vehicle doors. The latch system includes a movable door handle, a door latch mechanism, and a bypass mechanism defining an engaged configuration, a bypass configuration, and a home configuration. The latch system further includes a linkage assembly including first and second linkages that are connected to the bypass mechanism to operably interconnect the door handle and the door latch mechanism when the bypass mechanism is in its engaged configuration. The bypass mechanism includes a locking member that is connected to the first linkage. The locking member defines an axis, and includes an end and an outer surface that is spaced from the axis a first distance. The locking member further includes an outer second surface at the end of the locking member that is spaced from the axis a second distance that is less than the first distance. The locking member further includes a recess that is disposed between the outer first and second surfaces. The bypass mechanism further includes a lever that is pivotably connected to the second linkage for rotation about a second axis that is transverse to the first axis. The lever includes a hooked end portion that slidably engages the outer first surface when the bypass mechanism is in its home configuration. If the door handle is moved from a rest position to an actuated position by a user, the hooked end portion rotates into engagement with the recess to interconnect the lever with the locking member such that the first and second linkages are interconnected, and movement of the door handle shifts the first and second linkages and unlatches the door latch mechanism. If the door handle is moved from a rest position to an actuated position at a relatively high velocity due to a vehicle crash, the hooked end of the lever slides on the first outer surface and moves across the recess without engaging the recess, and slidably engages the outer second surface, such that the first and second linkages are disconnected, and the movement of the door handle does not unlatch the door latch mechanism. 
         [0005]    Another aspect of the present invention is a vehicle door latch assembly including a door handle that is operably connected to a latch by first and second cables. The first and second cables are releasably interconnected by a spring-biased rotating lever having a hooked end. The hooked end slidably engages an outer surface of a locking member, and then engages a groove of the locking member to interconnect the first and second cables only if the door handle moves at a speed below a predefined speed. 
         [0006]    These and other aspects, objects, and features of the present invention will be understood and appreciated by those skilled in the art upon studying the following specification, claims, and appended drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    In the drawings: 
           [0008]      FIG. 1  is a partially fragmentary schematic side elevational view of a vehicle door including a latch system having a bypass device according to one aspect of the present invention; 
           [0009]      FIG. 2  is a partially fragmentary schematic top plan view of the vehicle door handle and latch system of  FIG. 2 ; 
           [0010]      FIG. 3  is a cross sectional view of a bypass mechanism according to the present invention showing the bypass mechanism in a home configuration; 
           [0011]      FIG. 4  is a cross sectional view of the bypass mechanism of  FIG. 3  showing the bypass mechanism in an engaged configuration; 
           [0012]      FIG. 5  is a cross sectional view of the bypass mechanism in a released configuration; 
           [0013]      FIG. 6  is a cross sectional view of the bypass mechanism showing the bypass mechanism as it shifts from a disengaged configuration or an engaged configuration to the home configuration of  FIG. 3 ; and 
           [0014]      FIG. 7  is a fragmentary enlarged view of a portion of the lever and locking barrel of  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0015]    For purposes of description herein, the terms “upper,” “lower,” “right,” “left,” “rear,” “front,” “vertical,” “horizontal,” and derivatives thereof shall relate to the invention as oriented in  FIG. 1 . However, it is to be understood that the invention may assume various alternative orientations, except where expressly specified to the contrary. It is also to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification are simply exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered as limiting, unless the claims expressly state otherwise. 
         [0016]    With reference to  FIG. 1 , a motor vehicle  1  includes one or more doors  2  that are movably mounted to a vehicle structure  6  by one or more hinges  4 A,  4 B. A movable exterior door handle  8  is connected to a latch mechanism  14  by first and second linkages such as cables  10  and  12  and a bypass mechanism  20  that selectively interconnects cables  10  and  12 . Latch mechanism  14  engages a striker  16  when the latch mechanism  14  is in a latched state or configuration to thereby selectively retain the door  2  in a closed position. Latch mechanism  14  and striker  16  may comprise a conventional latch mechanism and striker of a type that is well known in the art. As discussed in more detail below, when exterior door handle  8  is moved outwardly by a user, the bypass mechanism  20  mechanically interconnects the cables  10  and  12  such that movement of the exterior door handle  8  by a user unlatches the latch mechanism  14  so it is no longer latched to striker  16 , thereby permitting the door  2  to open (provided the latch mechanism  14  is not in a locked configuration). However, in the event of a vehicle crash/side impact resulting in rapid outward movement of exterior door handle  8 , the bypass mechanism  20  will mechanically disconnect first and second cables  12  such that the rapid movement of exterior door handle  8  does not unlatch the latch mechanism  14 . 
         [0017]    With reference to  FIG. 2 , handle  8  may comprise a strap type handle of a known design having a body portion  18  defining a forward end  22  having a connecting structure  24  that rotatably engages a hinge pin or pivot  26  whereby the handle  8  rotates outwardly as shown by the arrow “A” about a vertical axis  28  relative to the door  2  to a released position shown in dashed lines  8 A. A spring such as torsion spring  25  biases the handle member  8  towards a closed position such that the handle  8  returns to the closed position after the handle  8  is released by a user. A rear end portion  30  of handle  8  is connected to an inner strand  32  of first cable  10 , such that outward movement of rear end portion  30  to the released position  30 A shifts strand  32  lengthwise. A first end of an outer sheath  34  of cable  10  is connected to a fitting  36  that is secured to the door  2 , and an opposite end of outer sheath  34  of cable  10  is connected to housing  42  of bypass mechanism  20  by a fitting  58  of a known type. Cable  12  may comprise an inner strand  38  and an outer sheath  40 . A first end of the outer sheath  40  is connected to housing  42  of bypass mechanism  20  utilizing a fitting  76  ( FIG. 3 ) of a known type, and the other end of outer sheath  40  is be connected to latch mechanism  14  utilizing a fitting  36  of a known type. The bypass mechanism  20  may be utilized in connection with a strap type exterior door handle  8  as shown in  FIG. 2 , or the bypass mechanism  20  may be utilized in connection with other types of moveable exterior door handles that are known in the art. 
         [0018]    With further reference to  FIG. 3 , the bypass mechanism  20  includes a main housing  44  having inner and outer cylindrical surfaces  46  and  48 , respectively and an end wall  50  having inner and outer surfaces  52  and  54 , respectively at a first end  56  of main housing  44 . A fitting  58  on end wall  50  connects the outer sheath  34  of cable  10  to the main housing  44 . A second or smaller housing  60  includes a first portion  62  having cylindrical inner and outer surfaces  64  and  66 , respectively, and an enlarged end portion  68  that is received in an open second end  70  of main housing  44 . The smaller housing  60  may be secured to the main housing  44  by welding, adhesives, crimping, or other suitable techniques. The housings  60  and  44  may be made from metal (e.g. steel), polymer, or other suitable material. The main housing  44  defines a generally cylindrical main cavity  72 , and the second housing  60  defines a generally cylindrical smaller second cavity portion that joins to the main cavity  72 . A fitting  76  is mounted on an end wall  78  of second housing  60 . The fitting  76  attaches the outer sheath  40  of second cable  12  to the second housing  60 . 
         [0019]    The bypass mechanism  20  also includes a lever support member  80  having a cylindrical outer surface  82  that slidably supports the lever support member  80  in the main housing  44  for reciprocating movement of lever support member  80 . End  84  of inner cable strand  32  is connected to lever support member  80 , such that lever support member  80  moves with inner cable strand  32 . A coil spring  86  is disposed around inner cable strand  32  between an end surface  88  of lever support member  80  and inner surface  52  of end wall  50  of main housing  44 . Coil spring  86  biases the lever support member  80  in the direction of the arrow “B” when coil spring  86  is compressed. Lever support member  80  includes a pair of extensions  90  that extend from end surface  92  of lever support member  80  to form a clevis  94 . A lever member  96  is rotatably connected to lever support member  80  at clevis  94  by a pin  98 . A second spring  102  is disposed in a cylindrical cavity  104  of lever support member  80 . The second spring  102  is a compression spring that bears against end surface  106  of lever member  96  to thereby bias the lever member  96  in the direction of the arrow “C” about the pin  98 . Second spring  102  may, alternatively, comprise a torsion spring (not shown) disposed about the pin  98 . As discussed in more detail below, the lever member  96  includes an end portion  108  that contacts a locking barrel member  110  when the bypass mechanism  20  is in the home configuration shown in  FIG. 3 . 
         [0020]    Locking barrel member  110  includes an elongated body portion  112  having a cylindrical first outer surface  114 . The locking barrel member  110  is slidably disposed in the second cavity  74  of second housing  60 . The locking barrel member  110  is connected to the inner cable strand  38  of second cable  12 , such that the locking barrel member  110  and inner cable strand  38  move together. Locking barrel member  110  further includes an end portion  116  having a tapered, conical outer surface  118 , and a cylindrical second outer surface  120 . An annular groove  122  is disposed between the cylindrical first outer surface  114  and the cylindrical second outer surface  120 . Annular groove  122  is defined by a cylindrical surface  124  having a diameter that is significantly less than the diameters of the first and second outer surfaces  114  and  120 , and spaced apart side surfaces  126  and  128 . 
         [0021]    In use, when exterior door handle  8  is in a closed or non-actuated rest position, the bypass mechanism  20  is in a home position or configuration as shown in  FIG. 3 . When bypass mechanism  20  is in the home configuration, end surface  130  of end  108  of lever member  96  is in sliding contact with cylindrical first outer surface  114  of locking barrel member  110 . The end surface  130  is biased into contact with the cylindrical first outer surface  114  by second spring  102 . If a user pulls outwardly on the exterior door handle  8 , inner cable strand  32  of first cable  10  will move in the direction of the arrow “D” ( FIG. 4 ). As the lever support member  80  moves in the direction of the arrow D, and the end  108  of lever member  96  will engage annular groove  122  due to the bias of second spring  102 . Side surface  132  of end  108  of lever member  196  then comes into contact with side surface  126  of annular groove  122  to thereby mechanically interconnect inner strands  32  and  38  of first and second cables  10  and  12 , respectively with respect to tension forces acting on cable strands  32  and  38 . Thus, as the exterior door handle  8  is pulled further towards its open position  8 A ( FIG. 2 ) movement of inner cable strand  32  causes movement of inner cable strand  38 . Movement of inner cable strand  38  causes latch mechanism  14  to unlatch, thereby permitting a user to open the vehicle door  2 . 
         [0022]    However, if the exterior door handle  8  is initially in a rest or non-actuated position, and the bypass mechanism  20  is in its home position or configuration ( FIG. 3 ), and if the exterior door handle  8  is moved outwardly at a high speed/velocity due to a side impact or the like, the bypass mechanism  20  will shift to the bypassed or disengaged configuration of  FIG. 5 . When bypass mechanism  20  is in the bypassed configuration, cable strand  32  is mechanically disconnected from inner cable strand  38  such that movement of cable strand  32  does not result in movement of inner cable strand  38 . Thus, when bypass mechanism  20  is in its bypass configuration, movement of the exterior door handle  8  does not unlatch the latch mechanism  14 . 
         [0023]    The first cylindrical first outer surface  114  of locking barrel member  110  has a diameter that is somewhat greater than the diameter of cylindrical second outer surface  120 . If lever support member  80  is moved in the direction of the arrow D ( FIG. 4 ) at a relatively high speed/velocity, the end surface  130  of end  108  of lever member  96  initially slides on cylindrical first outer surface  114  of locking barrel member  110 . However, if lever support member  80  is moving at a relatively high velocity, the end surface  130  “jumps” across the annular groove  122 , and then slidably engages the cylindrical second outer surface  120 . The end surface  130  of lever member  96  then slides off the tapered outer end surface  118  of locking barrel member  110 , thereby shifting the bypass mechanism  20  to the bypassed or disconnected configuration of  FIG. 5 . 
         [0024]    Although the second spring  102  biases the end  108  of lever member  96  towards the annular groove  122 , the second spring  102  may be selected to provide a relatively small biasing force such that the rotational inertia of lever member  96  results in a relatively slow rotational acceleration and velocity of lever member  96  as it slides off cylindrical first outer surface  114 . The mass/rotational inertia of lever member  96  and bias of second spring  102 , along with the dimensions of the cylindrical first outer surface  114 , cylindrical second outer surface  120 , and annular groove  122  can be selected such that the bypass mechanism  20  shifts to the engaged configuration ( FIG. 4 ) if handle  8  is moving at a relatively slow velocity, but shifts to the bypassed or disconnected configuration ( FIG. 5 ) if the exterior door handle  8  is moved at a relatively high speed/velocity. Specifically, a user will typically move the exterior door handle  8  outwardly at a speed that is less than 500 ms. Accordingly, the components of the bypass mechanism  20  can be selected such that the bypass mechanism  20  shifts from the home configuration ( FIG. 3 ) to the engaged configuration ( FIG. 4 ) if the exterior door handle  8  and cable  32  are moved at a speed of 500 ms or less. However, in the event the exterior door handle  8  moves outwardly at a relatively high velocity due to a side impact, the exterior door handle  8  will normally move at a speed of at least about 2000 ms to 2500 ms. Thus, the bypass mechanism  20  may be configured to shift from the home configuration ( FIG. 3 ) to the disconnected configuration ( FIG. 5 ) if the exterior handle and cable  32  move at a predefined speed that is significantly greater than 500 ms. In a preferred embodiment, the bypass mechanism  20  shifts from the home configuration ( FIG. 3 ) to the engaged configuration ( FIG. 4 ) if the exterior door handle  8  and cable  32  are moving at a speed greater than 1000 ms, and the bypass mechanism  20  shifts from the home configuration ( FIG. 3 ) to the bypass or disconnected configuration ( FIG. 5 ) if the exterior handle  8  and cable  32  are moving at a speed that is greater than 1000 ms. It will be understood that the various components of bypass mechanism  20  may be designed to provide a desired preselected speed at which the bypass mechanism  20  shifts from the home configuration to the disengaged configuration as required for a particular application. 
         [0025]    When the bypass mechanism  20  is in the engaged configuration ( FIG. 4 ) or the bypass configuration ( FIG. 5 ), the spring  86  is compressed, thereby generating a force tending to shift the lever support member  80  in the direction of the arrow “E” ( FIG. 6 ) Thus, after the exterior door handle  8  is released by a user, or as the exterior door handle  8  moves inwardly after a side impact due to the bias of spring  25  ( FIG. 2 ), the spring  86  will move the lever support member  80  towards the locking barrel member  110  to reset the bypass mechanism  20 . 
         [0026]    As shown in  FIG. 7 , end portion  108  of lever member  96  may include a radiused edge portion  134 . The radiused edge portion  134  slidably engages an edge  136  of locking barrel member  110  as the lever support member  80  moves towards the locking barrel member  110 . The sliding engagement of the radiused edge  134  on the edge  136  causes the lever member  96  to rotate outwardly away from the annular groove  122  despite the rotational bias of spring  102 , and the force of spring  86  returns the bypass mechanism  20  to the home position ( FIG. 3 ) wherein the end surface  130  of lever member  96  engages cylindrical first outer surface  114 . 
         [0027]    Referring again to  FIG. 7 , end  108  of lever member  96  may, alternatively, include a chamfer  138  instead of radiused edge  134 . Annular groove  122  may include a corresponding chamfer or ramp surface  140  rather than a side surface  128 . The chamfers  138  and  140  ensure that the lever member  96  shifts to the home position or configuration of  FIG. 3  as the lever support member  80  moves towards the locking barrel member  110  due to the bias of spring  86 . For example, if the bypass mechanism  28  is in the engaged configuration ( FIG. 4 ), and the exterior door handle  8  is released, the end  108  of lever member  96  will move from the position of  FIG. 4  to the home position of  FIG. 3  due to the sliding engagement of chamfers  138  and  140 . 
         [0028]    It is to be understood that variations and modifications can be made on the aforementioned structure without departing from the concepts of the present invention, and further it is to be understood that such concepts are intended to be covered by the following claims unless these claims by their language expressly state otherwise.