Abstract:
In one non-limiting embodiment, a latch assembly includes a claw movable between a latched position and an unlatched position, and a pawl movable between a first position and a second position. The system also includes a pawl lifter operatively associated with the pawl, the pawl lifter movable between a switch-off position when the pawl is in the first position and a switch-on position when the pawl is in the second position, and a pawl switch configured to generate a pawl switch signal, the pawl lifter engaging the pawl switch to an “on” condition when the pawl lifter is in the switch-on position, and the pawl lifter disengaging the pawl switch to an “off” condition when the pawl lifter is in the switch-off position.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims foreign priority to French Patent Application No. 13/62345 filed on Dec. 10, 2013, under 35 U.S.C. §119, the contents of which are incorporated herein by reference thereto. 
       BACKGROUND 
       [0002]    Exemplary embodiments of the present invention relate generally to latches and, more particularly, to latches for vehicles. 
         [0003]    Some known vehicles typically include displaceable panels such as doors, windows, hood, trunk lid, hatch and the like which are affixed for hinged or sliding engagement with a vehicle body. Cooperating systems of latches and strikers are typically provided to ensure that such panels remain secured in their fully closed position when the panel is closed. 
         [0004]    A latch typically includes a fork bolt or claw that is pivoted between an unlatched position and a primary latched position when the door is closed to latch the door in the closed position. The fork bolt is typically held in the primary latched position by a detent lever or pawl that pivots between an engaged position and a disengaged position. The detent lever holds the fork bolt in the primary latched position when in the engaged position and releases the fork bolt when in the disengaged position so that the door can be opened. 
         [0005]    The fork bolt is pivoted to the primary latched position by a striker attached to, for example, an associated doorjamb when the door is closed. Once in the primary latched position, the detent lever engages the fork bolt to ensure the assembly remains latched. 
         [0006]    In some known vehicles, doors may be automatically power closed by a motor when the door is in a certain position, for example, a first safety position. Due to a high clearance during transition to the latch closing position, a switch associated with the detent lever may fail to indicate when the door is closed. This may lead to the motor operating in a stall position for an undesirable amount of time. Accordingly, it is desirable to provide an improved latch assembly. 
       SUMMARY OF THE INVENTION 
       [0007]    In one non-limiting embodiment, a latch assembly is provided. The latch assembly includes a claw movable between a latched position and an unlatched position, and a pawl movable between a first position and a second position, the pawl engaging and holding the claw in the latched position when the pawl is in the first position, the pawl disengaging the claw for movement to the unlatched position when the pawl is in the second position. The system also includes a pawl lifter operatively associated with the pawl, the pawl lifter movable between a switch-off position when the pawl is in the first position and a switch-on position when the pawl is in the second position, and a pawl switch configured to generate a pawl switch signal, the pawl lifter engaging the pawl switch to an “on” condition when the pawl lifter is in the switch-on position, and the pawl lifter disengaging the pawl switch to an “off” condition when the pawl lifter is in the switch-off position. 
         [0008]    In another non-limiting embodiment, a vehicle is provided. The vehicle includes a controller, a door, and a door latch assembly. The door latch assembly includes a claw movable between a latched position and an unlatched position, and a pawl movable between a first position and a second position, the pawl engaging and holding the claw in the latched position when the pawl is in the first position, the pawl disengaging the claw for movement to the unlatched position when the pawl is in the second position. The assembly further includes a pawl lifter operatively associated with the pawl, the pawl lifter movable between a switch-off position when the pawl is in the first position and a switch-on position when the pawl is in the second position, and a pawl switch communicatively coupled to the controller, the pawl switch configured to generate a pawl switch signal, the pawl lifter engaging the pawl switch to an “on” condition when the pawl lifter is in the switch-on position, and the pawl lifter disengaging the pawl switch to an “off” condition when the pawl lifter is in the switch-off position. 
         [0009]    In yet another non-limiting embodiment, a method of detecting the position of a door of a vehicle is provided, the vehicle having a latch assembly including a claw, a pawl, a switch cam operatively associated with the claw, a pawl lifter operatively associated with the pawl, a pawl switch, and a controller. The method includes providing the claw movable between a latched position and an unlatched position, providing the pawl movable between a first position and a second position, the pawl engaging and holding the claw in the latched position when the pawl is in the first position, the pawl disengaging the claw for movement to the unlatched position when the pawl is in the second position, and operatively associating the pawl lifter with the pawl such that the pawl lifter is movable between a switch-off position when the pawl is in the first position and a switch-on position when the pawl is in the second position. The method further includes providing a pawl switch communicatively coupled to the controller and configured to generate a pawl switch signal, and orienting the pawl switch such that the pawl lifter engages the pawl switch to an “on” condition when the pawl lifter is in the switch-on position, and the pawl lifter disengages the pawl switch to an “off” condition when the pawl lifter is in the switch-off position. The method further includes indicating to the controller, with the pawl switch signal, a door open position condition of the latch assembly when the pawl switch is in the “on” condition, and indicating to the controller, with the pawl switch signal, a door safety position or closed condition of the latch assembly when the pawl switch is in the “off” condition. 
         [0010]    The above-described and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: 
           [0012]      FIG. 1  is a side view of a latch assembly in an open position according to an embodiment of the invention; 
           [0013]      FIG. 2  is a side view of the latch assembly in a safety position according to an embodiment of the invention; 
           [0014]      FIG. 3  is a side view of the latch assembly in a closed position according to an embodiment of the invention; 
           [0015]      FIG. 4  is a schematic view of an embodiment of a latch connector that may be used with the latch assembly shown in  FIGS. 1-3 ; 
           [0016]      FIG. 5  is a schematic view of another embodiment of a latch connector that may be used with the latch assembly shown in  FIGS. 1-3 ; 
           [0017]      FIG. 6  is a graph showing the operational relationship among the latch assembly, a claw switch, a pawl switch, and the latch connector shown in  FIG. 4 ; 
           [0018]      FIG. 7  is a chart showing the operational relationship among the latch assembly, the claw switch, the pawl switch, and the latch connector shown in  FIG. 4 ; 
           [0019]      FIG. 8  is a graph showing the operational relationship among the latch assembly, the claw switch, the pawl switch, and the latch connector shown in  FIG. 5 ; and 
           [0020]      FIG. 9  is a chart showing the operational relationship among the latch assembly, the claw switch, the pawl switch, and the latch connector shown in  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Described herein is an exemplary latch assembly that includes an integrated pawl switch for use in detecting a true position of a vehicle door, such as a power sliding door. The pawl switch is connected in parallel with a claw switch using existing electrical wiring such that the switches provide an electrical status of the latch in different door positions. 
         [0022]    Referring now to the FIGS., an exemplary latch assembly  10  is illustrated in an open position ( FIG. 1 ), an intermediate safety position ( FIG. 2 ), and a closed position ( FIG. 3 ). Latch assembly  10  may be integrated into a component of a vehicle, such as the vehicle door, trunk, frame surrounding the door opening or trunk opening, or any other operable component for example. Latch assembly  10  generally includes a claw  12 , a cooperating pawl  14 , a switch cam  16 , a pawl lifter  18 , a claw switch  20 , and a pawl switch  22 . 
         [0023]    Claw  12  is pivotally or rotationally mounted about a pin  56  that is received within an opening  24 . Claw  12  is capable of rotational movement between an open or unlatched position shown in  FIG. 1  and a closed or latched position shown in  FIG. 3 , wherein claw  12  rotates in the direction of arrows  26 . 
         [0024]    Latch assembly  10  is attached to a vehicle structure such that claw  12  is moved between the open position ( FIG. 1 ) and the closed position ( FIG. 3 ) when a door, window, lift gate, etc. is opened and closed and claw  12  engages a striker (not shown) that is attached to the door, window, lift gate, etc. In the exemplary embodiment, latch assembly  10  includes safety position ( FIG. 2 ) that is an intermediate position between the open position and the closed position. In other embodiments, latch assembly  10  is secured to the door, window, lift gate, etc. and the striker is secured to the vehicle body at an opening into which the door, window, lift gate, etc. is received. The cooperation of a claw and striker is well known and need not be described in detail. 
         [0025]    Pawl  14  is pivotally mounted by a stud  28  received within a stud aperture  30  formed within pawl  14 . Pawl  14  cooperates with claw  12  in a well-known manner to retain claw  12  in the safety position ( FIG. 2 ) and the closed position ( FIG. 3 ), or release claw  12  for return to the open position ( FIG. 1 ). That is, pawl  14  pivots between a release or disengaged first position shown in  FIG. 1  in the direction of arrows  32 , a closed or engaged second position shown in  FIG. 2 , and a closed or engaged third position shown in  FIG. 3 . In the exemplary embodiment, claw  12  is spring biased clockwise to the open position shown in  FIG. 1  or in the direction of arrow  34  by a biasing member (not shown; e.g., coil or torsion spring or other equivalent member) that has one end attached to claw  12  and the other end attached to a housing or other equivalent location. Similarly, a biasing member (not shown) biases pawl  14  in the direction of arrow  34 A against a face of claw  12 . 
         [0026]    In the exemplary embodiment, claw  12  has a surface  36  that slides along a complimentary surface  38  of pawl  14  when claw  12  rotates from the open position ( FIG. 1 ) to the closed position ( FIG. 3 ). Once in the closed position ( FIG. 3 ), a claw shoulder portion  40  engages a pawl shoulder portion  42  thus engaging claw  12  and securing it into the closed position when the striker is secured in a receiving opening  44  of claw  12 . Once the latch assembly  10  is in the closed position, pawl  14  is spring biased in the direction of arrow  34 A and shoulder  40  engages shoulder  42  such that claw  12  cannot rotate into the open position unless pawl  14  is moved back to the release position (e.g., moving shoulder  42  away from shoulder  40 ) allowing claw  12  to rotate in the direction of arrow  34  into the open position. 
         [0027]    Claw  12  also includes a second shoulder portion  46  that is engaged by pawl shoulder portion  42  when claw  12  has been engaged by the striker as the door is closed to the safety position ( FIG. 2 ), at which point the door is still slightly ajar, with little or no compression of its weather seals (not shown), for example. Once in the safety position ( FIG. 2 ), claw second shoulder portion  46  engages pawl shoulder portion  42  thus engaging claw  12  and securing it into the first safety position. Once latch assembly  10  is in the closed position, pawl  14  is spring biased in the direction of arrow  34 A and shoulder  46  engages shoulder  42  such that claw  12  cannot rotate into the open position unless pawl  14  is moved back to the release position (e.g., moving shoulder  42  away from shoulder  40 ) allowing claw  12  to rotate in the direction of arrow  34  into the open position. Further, in the exemplary embodiment, once latch assembly  10  is in the first safety position, a controller  48  in communication with a power closing mechanism  49  (shown schematically) actuates power closing mechanism  49  to transition assembly  10  to the closed position ( FIG. 3 ). 
         [0028]    In the exemplary embodiment, latch assembly  10  includes a pawl sensor assembly  50  and a claw sensor assembly  52 , which are in communication with controller  48 . 
         [0029]    Pawl sensor assembly  50  includes pawl switch  22  and pawl lifter  18 , which facilitates transitioning pawl switch  22  between an “on” condition and an “off” condition for communication with controller  48 . Pawl lifter  18  is pivotally or rotationally mounted by stud  28  received within stud aperture  30 , and pawl lifter  18  may rotate with pawl  14  during rotation of pawl lifter  18 . In the exemplary embodiment, pawl lifter  18  includes an engagement surface  54  configured to selectively engage pawl switch  22 . In the open position ( FIG. 1 ), engagement surface  54  is not in contact with pawl switch  22  such that pawl lifter  18  is in the switch-on position. Engagement surface  54  contacts pawl switch  22  when claw  12  is in the safety position ( FIG. 2 ) and in the closed position ( FIG. 3 ) such that pawl lifter  18  is in a switch-off position. 
         [0030]    Claw sensor assembly  52  includes claw switch  20  and switch cam  16 , which facilitates transitioning claw switch  20  between an “on” condition and an “off” condition for communication with controller  48 . Switch cam  16  is pivotally or rotationally mounted by a pin  56  received within claw opening  24 , and switch cam  16  may rotate with claw  12  during rotation of switch cam  16 . In the exemplary embodiment, switch cam  16  includes a contact surface  58  configured to selectively engage claw switch  20 . In the open position ( FIG. 1 ) and in the safety position ( FIG. 2 ), contact surface  58  is in contact with claw switch  20  such that switch cam  16  is in a switch-on position. Contact surface  58  does not contact claw switch  20  when claw  12  is in the closed position ( FIG. 3 ) such that switch cam  16  is in a switch-off position. 
         [0031]    In the exemplary embodiment, claw switch  20  and pawl switch  22  are each microswitches that provide a signal to controller  48 , as described herein in more detail. However, switches  20  and  22  may be any suitable switch or sensor that enables assembly  10  to function as described herein. Claw switch  20  is positioned to engage switch cam  16  such that rotation of claw  12  from the closed position to the safety position and/or open position causes claw switch  20  to transition from an “off” position to an “on” position. Although described as “off” and “on” positions, claw switch  20  have may any suitable position or condition that enables system  10  to function as described herein. In the “off” position, claw switch  20  sends a signal (or indicates a lack of a signal) to controller  48  to indicate that latch assembly  10  is in the closed position ( FIG. 3 ). In the “on” position, claw switch  20  sends a signal (or indicates a lack of a signal) to controller  48  to indicate that latch assembly  10  is in the safety position ( FIG. 2 ) or the open position ( FIG. 1 ). 
         [0032]    In the exemplary embodiment, pawl switch  22  is positioned to engage pawl lifter  18  such that rotation of pawl  14  from the first position ( FIG. 1 ) to the second position ( FIG. 2 ) or the third position ( FIG. 3 ) causes pawl switch  22  to transition from an “on” position to an “off” position. Although described as “off” and “on” positions, pawl switch  22  have may any suitable position or condition that enables system  10  to function as described herein. In the “off” position, pawl switch  22  sends a signal (or indicates a lack of a signal) to controller  48  to indicate that latch assembly  10  is in the first safety position ( FIG. 2 ) or the closed position ( FIG. 3 ). In the “on” position, pawl switch  22  sends a signal (or indicates a lack of a signal) to controller  48  to indicate that latch assembly  10  is in the open position ( FIG. 1 ). 
         [0033]    As shown in  FIG. 4 , latch assembly  10  includes an electrical circuit or latch connector  60  where pawl switch  22  is connected in parallel with claw switch  20  such that only two wires A, B are required to communicatively couple switches  20  and  22  to controller  48 .  FIG. 5  illustrates an alternative embodiment of latch connector  60  that includes a resistor  62  connected in serial with claw switch  20 , which facilitates controller  48  detecting when latch assembly  10  is in the safety position ( FIG. 2 ). As such, a different voltage is on the wire due to resistor  62 , which provides at least three different types of signals to controller  48 . For example, with reference to  FIGS. 6 and 8 , a 0 (zero) signal may indicate no resistance, a 0.5 signal may indicate an intermediate resistance, and a 1 signal may indicate a high resistance. Controller  48  may then translate these signals to determine the position or condition of latch assembly  10 . 
         [0034]    With reference to  FIGS. 6-9 , an exemplary operation of latch assembly  10  is described herein.  FIGS. 6-9  illustrate correlations among the position of a vehicle door corresponding to the position of latch assembly  10 , the output signal from claw switch  20 , the output signal from pawl switch  22 , and a signal result on latch connector  60  wire B.  FIGS. 6 and 7  illustrate correlations when latch connector  60  does not include resistor  62 , and  FIGS. 8 and 9  illustrate correlations when latch connector  60  includes resistor  62 . 
         [0035]    In the exemplary operation, claw  12  begins in an unlatched position ( FIG. 1 ) corresponding to a component such as a vehicle door being in an open position. Switch cam  16  is oriented in the switch-on position such that switch cam contact surface  58  contacts claw switch  20  into the “on” state where claw switch  20  sends a signal to controller  48  indicating the vehicle door is in the open/safety position. Pawl  14  is in the first position and pawl lifter  18  is oriented in the switch-on position such that pawl lifter engagement surface  54  does not contact pawl switch  22 . As such, pawl switch  22  is in the “on” state where pawl switch  22  sends a signal to controller  48  that indicates the vehicle door is in the open position. Accordingly, switches  20 ,  22  indicate to controller  48  that the vehicle door is open. 
         [0036]    As the vehicle door moves from the open position ( FIG. 1 ) to the safety position ( FIG. 2 ), claw  12  rotates counter-clockwise and pawl  14  rotates from the first position ( FIG. 1 ) where it is disengaged from claw  12  to the second position ( FIG. 2 ) where pawl shoulder  42  engages claw shoulder  40  to prevent the vehicle door from accidentally moving to the open position. As such, contact surface  58  remains in contact with claw switch  20 , and pawl  14  has rotated clockwise causing engagement surface  54  to contact pawl switch  22 , thereby transitioning switch  22  to the “off” condition. As such, claw switch  20  sends a signal to controller  48  indicating that the vehicle door is in the open or safety position, and pawl switch  22  sends a signal to controller  48  that indicates the vehicle door is in the safety or closed position. Controller  48  may subsequently actuate the motor of power closing mechanism  49  to commence a power close operation where claw  12  is rotated counter-clockwise into the latched position ( FIG. 3 ) to safely secure the door in a closed position. 
         [0037]    As the vehicle door moves from the safety position ( FIG. 2 ) to the closed position ( FIG. 3 ), claw  12  rotates to the latched position and pawl  14  rotates to the third position ( FIG. 3 ). Accordingly, in the door closed position, engagement surface  54  remains in contact with pawl switch  22 , and switch cam  16  has been rotated out of engagement with claw switch  20 , thereby transitioning switch  20  to the “off” condition. As such, claw switch  20  sends a signal to controller  48  that indicates the vehicle door is in the closed position. Controller  48  may then cease the power close operation and power-off the power close mechanism motor. 
         [0038]    As the vehicle door returns to the open position ( FIG. 1 ), pawl  14  disengages claw  12 , and claw  12  rotates clockwise from the latched position ( FIG. 3 ) to the unlatched position ( FIG. 1 ). As such, contact surface  58  engages claw switch  20  indicating to controller  48  a door open or safety position, and pawl lifter  18  rotates out of engagement with pawl switch  22  indicating to controller  48  a door open position. The operation of latch assembly  10  may then be repeated as the door again moves from the open position ( FIG. 1 ), to the safety position ( FIG. 2 ), and to the closed position ( FIG. 3 ). 
         [0039]    Described herein is a latch assembly for detecting a position of a vehicle door. The latch assembly includes a claw switch and a pawl switch connected in parallel. Economically, the claw switch and pawl switch may be coupled in parallel using only two wires. The switches are communicatively coupled to a controller (e.g., vehicle electronics) and are selectively engaged by portions of the latch assembly to indicate various positions of the vehicle door depending on whether the switches are in an “on/off” condition. Further, a resistor may be coupled in serial with the claw switch. Accordingly, the dual switches facilitate improved indication of door position, and thus, improved door operation, improved door closure safety, and increased vehicle occupant safety. 
         [0040]    While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.