Abstract:
A powered vehicle door system and method in which a motor-driven door opening and closing mechanism and a motor-driven latching mechanism cooperate to enable the door to open from a latched, fully-closed position with improved noise control and improved smoothness of operation. The door can be a tailgate or a swinging or sliding door, and the opening and closing mechanism is operative to place the door in an over-closed position, thus reducing or eliminating the inherent tension placed upon the latch from the compressive force of the seal interposed between the door and the door frame. Optionally, the door latching mechanism assists the door opening and closing mechanism in placing the door in the over-closed position.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to the automatic power release and opening of the closed and latched tailgate of a vehicle. In particular, the invention relates to minimizing, or substantially eliminating, the uneven motion of the tailgate and the significantly audible “pop” or “snap” sound that is emitted when the tailgate is released by the latch preparatory to opening. 
     2. Description of the Related Art 
     Many vehicles, particularly sport utility vehicles (SUVs), and more particularly so-called luxury SUVs, employ a power rear tailgate that can be automatically opened and closed with, for example, a system comprising switches capable of initiating an action, microcontrollers capable of receiving signals from the switches, and motors capable of effecting the initiated action, such as closing and latching or unlatching and opening the tailgate, via the microcontrollers. For example, when the tailgate is in an open position and one desires to close and latch it, a switch is first closed to initiate the desired (closing) action. This switch may be located in the passenger compartment within reach of the driver. It may also be contained within a handheld wireless remote control device, usually attached to the vehicle ignition key, carried by the driver. The signal from the switch is then transmitted to motors which effect the closing of the tailgate. In an exemplary system, there are two motors, one that rotates the tailgate between the open and closed position and one that latches and unlatches the tailgate. The tailgate opening and closing means, comprising a tailgate actuator and a tailgate actuator arm, is secured to the body, or frame, of the vehicle and operatively connected to the tailgate. The latching means is also secured to the body of the vehicle and includes a latch which is adapted to engage a catch secured to the tailgate. 
     Further included is a compressible seal interposed between the tailgate and the tailgate frame and generally attached to the tailgate frame itself. When the tailgate is in the fully-closed position, the seal fills what would otherwise be gaps between the tailgate and the tailgate frame, thus helping to reduce entry of road and other external noise from the passenger compartment, inhibit rattles between the tailgate and the tailgate frame, and keep water, dust, and other unwanted matter from entering the vehicle. 
     Due to mechanical design considerations, particularly due to the elastic force exerted by the typical compressible seal, the tailgate actuator, or motor, and its associated mechanical system are generally not strong enough to close the tailgate from a nominally-closed position, where the tailgate is resting on a nominally-compressed seal, to a fully-closed position, where the seal is further compressed. When closing the tailgate, the latch actuator and latch system are employed to engage the catch and pull the tailgate into the latched, fully-closed position. Preparatory to opening the tailgate, the latch actuator then causes the latch to disengage from the catch. Unfortunately, this disengaging action, in which the catch slips from the confines of the latch, occurs quite suddenly because the engaged structures are under tension due to the compressed, elastic seal. This tension causes an undesirable loud “pop” or “snap” sound as the compressed seal exerts an opening force on the tailgate. Further, the opening motion of the tailgate appears uneven or abrupt. These events, especially with respect to a luxury vehicle, detract from the refined image such a vehicle should project. 
     Therefore, there is a need for a vehicle tailgate release and opening system that minimizes or reduces the loud popping sound and the sharp jerking motion currently associated with the opening of powered vehicle tailgates. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object of an exemplary embodiment of the present invention to provide a door release and opening system, the preferred embodiment of which comprises a vehicle having a body and a door, such as the tailgate, pivotably attached to the body. The tailgate includes a catch secured thereto. A tailgate frame is attached to the body and a tailgate opening and closing means is connected to the tailgate and to the body of the vehicle. A tailgate latching means is connected to the body of the vehicle. The latching means comprises a latch attached thereto, wherein the latch is adapted to engage the catch. An elastic, compressible seal is interposed between the tailgate and the tailgate frame. A first switch is operatively connected to the tailgate opening and closing means and a second switch is operatively connected to the tailgate latching means. 
     The tailgate is initially held by the latch engaged with the catch in a latched, fully-closed position, P F . The subscript “F” herein denotes the fully-closed position. The tailgate is close to, and separated by a distance S F  from, the frame, and the seal is compressed to full compression, C F . As will be appreciated by those skilled in the art, the degree of “compression” refers to the amount of force by which the compressible seal is compressed. A first signal from the first switch to the tailgate opening and closing means is effective to cause the tailgate opening and closing means to apply a further closing force to the tailgate whereby the tailgate is urged to an over-closed position, P O . The subscript “O” herein denotes the over-closed position. The separation distance between the tailgate and the frame is thus reduced to S O , and the seal is further compressed to an over-closed compression, C O . In a preferred embodiment, the further closing force is effected by powering the tailgate opening and closing means with a low-stall torque which is increased until terminal voltage (full V BATT ) is reached. Thus, the distance S F  is greater than the distance S O  and the compression C O  is greater than the compression C F  as the tailgate is urged closer to the vehicle body, from a fully-closed position to an over-closed position. 
     A second signal from the second switch to the tailgate latching means is effective to disengage the latch, now under reduced or no tension by the seal or other structure, from the catch. The tailgate is then unconstrained by the latch, and so long as the tailgate remains substantially at P O , the separation distance remains at substantially S O , and the seal compression remains at substantially C O  due to the force applied by the tailgate opening and closing means. In a preferred embodiment, however, the power to the tailgate opening and closing means is subsequently reduced until the tailgate opening and closing means is unpowered. Optionally, a third signal from a third switch to the tailgate opening and closing means is effective to apply an opening force to the tailgate and the tailgate at least partially opens. Because the compressive force of the seal is at least partially overcome by the tailgate opening and closing means when the latch is disengaged from the catch, the popping sound and the sharp jerking motion upon release by the latching means is reduced or eliminated. The tailgate opening and closing means can thus smoothly open the tailgate to its fully-open position. 
     In a further embodiment, a fourth switch is in operative connection with the tailgate latching means and is operative to cause a fourth signal to be transmitted to the tailgate latching means effective to draw the tailgate from the fully-closed position, P F , to the over-closed position, P O . Thus, the tailgate latching means assists the tailgate opening and closing means in urging the tailgate from the fully-closed position, P F , to the over-closed position, P O . 
     In a further alternative embodiment for releasing and opening a tailgate of a vehicle, the tailgate is initially in a latched, fully-closed position, P F , a first portion of the tailgate is close to, and separated by a distance S F  from, a first portion of a tailgate frame, and the tailgate is compressing a compressible seal interposed between at least a portion of the tailgate and at least a portion of the frame to C F . A signal is transmitted to a tailgate opening and closing means, whereby the tailgate is urged in a closed direction, to apply a closing force to the tailgate. The tailgate is thus urged in the closed direction to an over-closed position, P O , the separation distance between the first portion of the tailgate and the first portion of the frame is reduced to S O , and the seal is further compressed to C O . A signal is also transmitted to a tailgate latching means to move the latch to the unlatched position, whereby the latch moves to the unlatched position and the tailgate is unconstrained by the latch. Thus, S N  is greater than S F  and S F  is greater than S O  and C O  is greater than C F  and C F  is greater than C N . The subscript “N” herein denotes the nominally-closed position. Optionally, a signal is also transmitted to the tailgate opening and closing means to open the tailgate, whereby the tailgate at least partially opens. 
     In a further alternative embodiment, the tailgate latching means is further operative to move the latch to draw the tailgate from the latched, fully-closed position, P F , to the over-closed position, P O , and is signaled to apply a drawing force to the tailgate, whereby the tailgate is further urged in the closing direction to the over-closed position, P O . Thus, the tailgate latching means assists the tailgate opening and closing means in moving the tailgate from the fully-closed position, P F , to the over-closed position, P O . 
     In a further alternative embodiment, the signals are initiated from the passenger compartment of the vehicle. In a further alternative embodiment, the signals are initiated from a hand-held wireless transmitter. 
     In a further alternative embodiment, a signal is transmitted to a first actuator in operative connection with the tailgate of a vehicle, to apply a closing force to the tailgate in a first closed position, whereby the tailgate is urged to a second closed position. A signal is transmitted to a second actuator in operative connection with the tailgate latch, whereby the latch is moved from an engaged to a disengaged position. Additionally, a compressible seal may be interposed between at least a portion of the tailgate and at least a portion of the tailgate frame and, in the first closed position, the tailgate compresses the seal to C F  and, in the second closed position, the tailgate compresses the seal to C O  and C O  is greater than C F . Alternatively, a compressible seal is interposed between at least a portion of the tailgate and at least a portion of the tailgate frame and in the first closed position, a first portion of the tailgate is proximate to, and separated by a distance S F  from, a first portion of the frame and in the second closed position, the separation distance between the first portion of the tailgate and the first portion of the frame is S O  and S F  is greater than S O . 
     In a further alternative embodiment, a tailgate, having a catch secured thereto, is initially in a latched, fully-closed position, P F , and held in the latched, fully-closed position, P F , by a tailgate latch, the latch extendably operative to enable the tailgate to move between the latched, fully-closed position, P F , and a nominally-closed position, P N . The latch is operative to move between an engaged position and a disengaged position relative to the tailgate catch. In the latched, fully-closed position, P F , the tailgate compresses a compressible seal interposed between at least a portion of the tailgate and at least a portion of the tailgate frame. The latch is extended, whereby the tailgate moves from the latched, fully-closed position, P F , to the nominally-closed position, P O , the distance from a first portion of the tailgate to a first portion of the tailgate frame increases from S F  to S N , the seal is decompressed from C F  to C N , C F  is greater than C N , and S N  is greater than S F . Subsequently, the latch is moved from the engaged position to the disengaged position and the tailgate is free to at least partially open. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a side view illustrating a rear portion of a vehicle including a powered tailgate. 
         FIG. 2  is a partial cutaway side view illustrating the rear portion of the vehicle shown in  FIG. 1  including a tailgate catch and a power latch mechanism. 
         FIG. 3   a  is a partial cutaway side view illustrating the rear portion of the vehicle shown in  FIGS. 1 and 2  including a compressible seal with the tailgate in a nominally-closed position. 
         FIG. 3   b  is a partial cutaway side view illustrating the rear portion of the vehicle with the tailgate in a fully-closed position. 
         FIG. 3   c  is a partial cutaway side view illustrating the rear portion of the vehicle with the tailgate in an over-closed position. 
         FIG. 4   a  is a flowchart illustrating the operation of an embodiment of the present invention. 
         FIG. 4   b  is a flowchart illustrating the operation of an embodiment of the present invention. 
         FIG. 5  is a flowchart illustrating the operation of an embodiment of the present invention. 
         FIG. 6  is a flowchart illustrating the operation of an embodiment of the present invention. 
         FIG. 7  is a flowchart illustrating the operation of an embodiment of the present invention. 
         FIG. 8  is a flowchart illustrating the operation of an embodiment of the present invention. 
         FIG. 9  is a side view illustrating a rear portion of the vehicle shown in  FIG. 1  with alternative locations for the tailgate catch, latch, and opening/closing means. 
         FIG. 10  is a side view illustrating a vehicle with a power sliding door. 
         FIG. 11  is a is a partial cutaway side view illustrating the rear portion of a vehicle including a compressible seal with the tailgate in a nominally-closed position. 
         FIG. 12  is a partial cutaway side view illustrating the rear portion of the vehicle of  FIG. 11  with the tailgate in a fully-closed position. 
     
    
    
     In describing the various embodiments of the invention which is illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific term so selected and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. 
     DETAILED DESCRIPTION OF THE INVENTION 
     A power door system is shown in  FIG. 1 . In the invention, the term “door” is defined broadly to include any vehicle body closure that opens and/or closes under the power of prime movers, including, without limitation, electric motors and hydraulic/pneumatic rams. Thus, the term “door” includes, but is not limited to, sliding doors, doors that swing along a hinge, hinged tailgates and any other passenger compartment or cargo compartment body closure that is opened and/or closed under power, as opposed to completely manually. 
     A vehicle  11  comprises a body  13  and a tailgate  10  pivotably attached to the vehicle  11  at a hinge  12 . A tailgate frame  14  is also part of the vehicle, as is a tailgate opening and closing means  116 , comprising a tailgate actuator  16 , such as a motor, and a tailgate actuator arm  18 . The tailgate actuator arm  18  is preferably a conventional elongated, telescoping structure, possibly having teeth or threads formed in one or more ends thereof which engage with teeth or threads of a driven gear of the tailgate actuator  16 .  FIG. 2  further illustrates the exemplary power tailgate system shown in  FIG. 1  and shows a catch  20 , which can be a metal loop, as is conventional, secured to the tailgate  10 . A tailgate latching means  126  comprises a latch actuator  26 , such as a motor, and a clinch latch  28 , which may be a hook or “L-shape”, both of which are conventional. Also included is a compressible seal  30 , generally attached to the tailgate frame  14 , but optionally attached to the tailgate  10  itself and interposed between the tailgate  10  and the tailgate frame  14 . The compressible seal  30  can be a conventional elastomeric automobile seal. 
     A first switch  15  (shown in  FIG. 2 ) is operative to actuate the tailgate opening and closing means  116  to urge the tailgate  10  from a fully-closed position to an over-closed position. A third switch  115  is operative to actuate the tailgate opening and closing means  116  to urge the tailgate  10  to open, and is operatively connected to the tailgate opening and closing means  116 . Also shown in  FIG. 2  are a second switch  25 , operative to actuate the latch actuator  26  to disengage the latch  28  from the catch  20  and a fourth switch  125 , operative to actuate the latch actuator  26  to apply a drawing force to the latch  28 . When the drawing force is applied, the tailgate  10  is drawn to the over-closed position. A fifth switch  225  is operatively connected to the tailgate latching means  126  and is operative to apply an extension force, which is in the opposite direction to the drawing force, to the latch  28 . 
     A switch (not shown) controls the closing of the tailgate  10  via the tailgate opening and closing means  116  from a fully-open position. In operation, starting with the tailgate  10  in an open position allowing access to the interior of the vehicle  11  from outside the vehicle  11 , the tailgate closing switch is closed and a signal is communicated to the tailgate actuator  16  to move the tailgate  10  to a closed position. As will be understood by those skilled in the art, the signal to close may be effected via a microcontroller (not shown) with which the tailgate closing switch is in operative connection. Alternatively, the switch may be included within the microprocessor and the closing action initiated with the closing of a single switch in a passenger compartment of the vehicle or from a hand-held wireless device such as a remote control. 
     Upon reaching a nominally-closed position, P N , ( FIG. 3   a ), the tailgate  10  rests on the seal  30 , nominally applying a compressing force C N  to the seal  30 . The tailgate  10  is nominally separated from the tailgate frame  14  at a separation distance S N    32 . The tailgate latching means  126  causes the latch  28  to engage with the catch  20 . In this configuration, the tailgate  10  is latched, but the seal  30  is not yet significantly compressed. As will be appreciated by those skilled in the art, it is desirable not to provide power to the tailgate opening and closing means  116  sufficient to drive the tailgate  10  into a fully-closed and latched position, P F , by itself. This can be, for example, because the tailgate opening and closing means  116  cannot provide the torque required. Therefore, the tailgate latching means  126  is operative to urge the tailgate  10  into the fully-closed position, P F . As will be further appreciated by those skilled in the art, signals transmitted to the tailgate latching means  126  may also be effected via a microcontroller (not shown). As will be still further appreciated by those skilled in the art, the entire opening or closing step herein described may be initiated by a single physical switch and further switching effected by the microcontroller. 
     When the tailgate latching means  126  urges the tailgate  10  toward the fully-closed position, P F , from the nominally-closed position P N  the latch  28 , starting in an extended position, is drawn in a closing direction by the latch actuator  26 . As the latch  28  is moved, it thereby draws the attached tailgate  10  from the nominally-closed position, P N , ( FIG. 3   a ) to the fully-closed and latched position, P F , where the seal  30  is further compressed to C F  and the tailgate  10  is separated from the tailgate frame  14  at a separation distance S F    34 . ( FIG. 3   b .) The fully-compressed seal, C F , and tailgate position, P F , is the condition in which the seal  30  is compressed and maintained when the vehicle is in a condition to be driven. As will be appreciated by those skilled in the art, C F  is greater than C N  (greater compression force when fully closed) and S N  is greater than S F  (smaller gap when fully closed). 
     When it is desired to open the tailgate  10  using a first embodiment of the invention, the first switch  15  is closed and the tailgate opening and closing means  116  urges the tailgate  10  from the fully-closed position with a separation distance of S F    34  and a seal compression of C F  to an over-closed position, P O , with a separation distance of S O    36  and a seal compression of C O . ( FIG. 3   c .) The over-closed position, P O , is accomplished by displacing the tailgate  10  to a closed position beyond the fully-closed position, P F , to compress the seal  30  beyond the full-compressed state, C F . As will be appreciated by those skilled in the art, C O  is greater than C F  and S F    34  is greater than S O    36 . ( FIGS. 3   b ,  3   c , and  4   a .) Once the over-closed position, P O , is accomplished (shown in  FIG. 3   c ), the latch  28  is released, such as by displacing the latch  28  laterally in a conventional manner to release the catch  20 . At this point, the tailgate  10  has been moved beyond the fully-closed position, P F , thereby releasing or reducing tension on the latch  28  from the elastic force of the compressed seal  30 . Thus, when a signal from the second switch  25  causes the latch  28  to disengage from the catch  20 , the undesirably loud “pop” or “snap” traditionally associated with such disengagement is reduced or eliminated. Additionally, the tailgate  10  does not make an uneven or abrupt motion. Once the latch  28  is disengaged, the tailgate  10  may then be opened by the tailgate opening and closing means  116 , upon activation of the third switch  115  as described above, which is a smooth motion. ( FIGS. 2 and 6 .) Thus, the step of over-compressing the seal  30  prior to disengagement of the latch  28  eliminates or significantly reduces the audible and visible result of the sudden release of the potential energy of the compressed seal  30 . The potential energy is instead released more gradually by the tailgate opening and closing means  116  releasing the compressive force on the seal  30 . 
     The process described above is not the only method by which the potential energy of the compressed seal  30  may be gradually released. Turning now to  FIG. 4   b , again with the tailgate  10  in the fully-closed position seated on the seal  30 , an alternate method is described. The tailgate  10  is separated from the tailgate frame  14  by a separation distance S F    34  and the seal  30  is fully compressed to C F    34  by the latch actuator  26 . ( FIG. 3   b .) The first switch  15  is closed and the tailgate opening and closing means  116  urges the tailgate  10  from the fully-closed position with a separation distance S F    34  and a seal compression of C F  to an over-closed position, P O , with a separation distance of S O    36  and a seal compression of C O . ( FIGS. 3   c  and  4   b .) Additionally, the tailgate latching means  126 , and in particular the latch actuator  26 , is employed, via a signal from the fourth switch  125 , to assist in moving the tailgate  10  from the fully-closed position to the over-closed position. ( FIG. 4   b .) In an alternative, the latch actuator  26  first over-compresses the seal  30 , then the tailgate opening and closing means  116  applies a closing force to hold the tailgate  10  in the over-closed position, P O . Tension on the latch  28  from the compressive force of the seal  30  is thus overcome or reduced such that when a signal from the second switch  25  causes the latch  28  to disengage from the catch  20 , the undesirable loud “pop” or “snap” traditionally associated with such disengagement, is reduced or eliminated. Further, the tailgate  10  does not open in an uneven or abrupt motion. The tailgate  10  may then be smoothly fully opened upon activation of the third switch  115 . ( FIG. 7 .) Additionally, via a signal from the fifth switch  225 , the latch  28  may be extended before the signal is sent from the second switch  25  that causes the latch  28  to disengage from the catch  20 . By extending the latch  28 , which is movement of the latch  28  in the direction opposite to drawing of the latch  28 , the distance between the latch  28  and the catch  20  is increased. 
     Turning now to  FIGS. 5 and 8 , which illustrate a still further alternative embodiment, again with the tailgate  10  in the fully-closed position seated on the seal  30 , the tailgate is separated from the tailgate frame  14  by a separation distance S F    34  and the seal is compressed to C F . ( FIG. 3   b .) The fifth switch  225  is closed and the tailgate latching means  126  extends the latch  20  and allows the compressive force on the seal  30  to urge the tailgate  10  from the fully-closed position with a separation distance of S F    34  and a seal compression of C F  to the nominally-closed position, P N , with a separation distance S N    32  ( FIG. 3   a ) and a seal compression of C N . ( FIGS. 5 and 8 .) Tension on the latch  28  from the compressive force of the seal  30  is thus relaxed or reduced such that when a signal from the second switch  25  causes the latch  28  to disengage from the catch  20 , the undesirable “pop” or “snap” traditionally associated with such disengagement is reduced or eliminated. Further, the tailgate  10  does not open in an uneven or abrupt motion. The tailgate  10  may then be smoothly opened upon activation of the third switch  115 . ( FIG. 8 .) 
     Referring now to  FIG. 9 , the tailgate actuator (not shown) can be mounted to the body  200  of the vehicle  210  at location A, as in the embodiments of the invention described above, with the tailgate actuator arm  220  mounted to the tailgate  230  at location B. Alternatively, it is contemplated that the actuator can be mounted to the tailgate  230  at location B, with the tailgate actuator arm  220  mounted to the body  200  at location A. It is further contemplated the tailgate actuator can be mounted within the actuator arm  220 , for example, at location C, with one end of the actuator arm  220  mounted to the body  200  at location A, and the opposite end of the arm  220  mounted to the tailgate  230  at location B. The alternative placements of the actuator can be applied to each of the above-described embodiments of the invention without substantively altering the function and interaction of the various component parts described. 
     Still referring to  FIG. 9 , it is similarly contemplated that both the latching means (not shown) and the catch (not shown) can be alternatively mounted to either the vehicle body  200  at location D, or to the tailgate  230  at location E. If the latching means is mounted to the body  200  at location D, the catch is mounted to the tailgate  230  at location E (as in the embodiments described above). Alternatively, if the latching means is mounted to the tailgate  230  at location E, the catch is mounted to the body  200  at location D. As with the alternative placements of the actuator, the alternative placement of the latching means and the catch can be applied to each of the above-described embodiments of the invention without substantively altering the function and interaction of the various component parts described. 
     In an alternative embodiment of the invention shown in  FIG. 11 , a vehicle has a body with a tailgate  410  pivotably attached to the vehicle at a hinge as in the embodiments described above. A tailgate frame  414  is also part of the vehicle, as is a tailgate opening and closing means, substantially the same as the structures shown and described above. The alternative power tailgate system has a catch  420 , which can be a U-shaped metal loop, as is conventional, secured to the tailgate frame  414 . A tailgate latching means comprises a latch actuator  426 , such as a motor, and a clinch latch  428 , which may be a U-shaped body that is rotatably displaced by the latch actuator  426 . The latch actuator  426  and the clinch latch  428  are mounted in the tailgate  410 . A compressible seal  430  is attached to the tailgate frame  414  or the tailgate  410 , and is interposed between the tailgate  410  and the tailgate frame  414 . 
     A switch is operative to actuate the latch actuator  426  to engage the latch  428  on the catch  420 , such as by rotating the latch  428  to extend the leg  428   a  into the opening between the legs of the U-shaped catch  420 . This movement traps the base of the U-shaped catch  420  between the legs  428   a  and  428   b  of the latch  428 , as shown in  FIG. 12 . A switch is operative to actuate the latch actuator  426  to apply a drawing force to the catch  420  by rotating the latch  428 . When the drawing force is applied, the tailgate  410  is drawn to the over-closed position. A switch is operatively connected to the tailgate latching means  426  and is operative to apply an extension force, which rotates the latch  428  in the opposite direction to the drawing force. 
     A switch (not shown) controls the closing of the tailgate  410  via the tailgate opening and closing means from a fully-open position. In operation, starting with the tailgate  410  in an open position, the tailgate closing switch is closed and a signal is communicated to the tailgate actuator to move the tailgate  410  to a closed position. Upon reaching a nominally-closed position, P N , ( FIG. 11 ), the tailgate  410  rests on the seal  430 , nominally applying a compressing force C N  to the seal  430 . The tailgate  410  is nominally separated from the tailgate frame  414  at a separation distance S N . The tailgate latching means  426  causes the latch  428  to engage with the catch  420 . In this configuration, the tailgate  410  is closed, but the catch  420  is not latched, nor is the seal  430  significantly compressed. 
     When the tailgate latching means  426  urges the tailgate  410  toward the fully-closed position, P F , from the nominally-closed position P N  the latch  428 , starting in an extended position (shown in  FIG. 11 ), is drawn in a closing direction by the latch actuator  426  rotating the latch  428 . As the latch  428  is rotated, it draws the attached tailgate  410  from the nominally-closed position, P N , ( FIG. 11 ) to the fully-closed and latched position, P F , where the seal  430  is further compressed to C F  and the tailgate  410  is separated from the tailgate frame  414  at a separation distance S F  (see  FIG. 12 ). The fully-compressed seal, C F , and tailgate position, P F , is the condition in which the seal  430  is compressed and maintained when the vehicle is in a condition to be driven. 
     When it is desired to open the tailgate  410  using the alternative embodiment of the invention shown in  FIGS. 11 and 12 , a switch is closed and the tailgate latching means  426  rotates still further and urges the tailgate  410  from the fully-closed position with a seal compression of C F  to an over-closed position, P O , with a separation distance of S O  and a seal compression of C O . The over-closed position, P O , is accomplished by displacing the tailgate  410  beyond the fully-closed position, P F , to compress the seal  430  beyond the full-compressed state, C F . This is not illustrated, but is analogous to the over-closed position shown in  FIG. 3   c.    
     Once the over-closed position, P O , is accomplished, the tailgate opening and closing means applies a tailgate-closing force on the tailgate  410 . The tailgate  410  is held in this position by the tailgate-closing force and the tailgate latching means  426  is then actuated to rotate the latch  428  in a tailgate-opening direction, which is toward the fully-closed position from the over-closed position. Because the tailgate  410  has been moved beyond the fully-closed position, P F , by the tailgate latching means  426 , and held in that position by the tailgate opening and closing means (thereby releasing or reducing the tension on the latch  428  from the elastic force of the compressed seal  430 ), when a signal from the switch causes the latch  428  to rotate to release the catch  420 , the undesirably loud “pop” or “snap” traditionally associated with such disengagement is reduced or eliminated. Additionally, the tailgate  410  does not make an uneven or abrupt motion. 
     Once the latch  428  is disengaged from the catch  420 , the tailgate  410  may then be opened by the tailgate opening and closing means, upon activation of a switch as described above. Thus, the step of over-compressing the seal  430  prior to disengagement of the latch  428  eliminates or significantly reduces the audible and visible result of the sudden release of the potential energy of the compressed seal  430  as with the above-described embodiment. The potential energy is instead released more gradually by the tailgate opening and closing means releasing the compressive force on the seal  430 . 
     It is further contemplated that all of the embodiments of the invention described above can be applied to the opening and closing of a conventional power sliding door, such as those commonly used in minivan applications, in a manner that will be apparent to those skilled in the art. Referring to  FIG. 10 , for example, the power sliding door  300  of the minivan  310  slides in a conventional manner along a horizontal track  320  in the minivan body  330  between an open position and a nominally-closed position. When in the nominally-closed position, the door  300  can be moved inwardly, towards the vehicle body  330 , to a fully-closed position in which the exterior of the door  300  is flush with the exterior of the vehicle body  330  and the door seal (not within view) that lines the door frame is nominally-compressed. 
     A conventional catch (not within view), similar to the catch  20  in  FIG. 1 , is mounted within the sliding door  300  at location A. A sliding door latching means (not within view), similar to the tailgate latching means  126  in  FIG. 1 , is mounted within the door frame at location B for engaging the catch when the door  300  is in the fully-closed position. A sliding door opening and closing means (not within view), similar to the tailgate opening and closing means  116  in  FIG. 1 , is mounted within the body  330  at location C, and operatively engages the sliding door  300  for moving the door  300  back and forth in the horizontal direction. It is contemplated that the location of the latching means and the catch may be reversed, with the latching means mounted within the door  300  and the catch mounted to the door frame. 
     Similar to the first embodiment of the invention described above, a first switch is operative to actuate the sliding door opening and closing means to urge the door  300  from a fully-closed position to an over-closed position. A third switch is operative to actuate the opening and closing means to urge the door  300  to open, and is operatively connected to the opening and closing means. A second switch is operative to actuate the latch actuator to disengage the latch from the catch and a fourth switch is operative to actuate the latch actuator to apply a drawing force to the latch. When the drawing force is applied, the door  300  is drawn to the over-closed position. A fifth switch is operatively connected to the door latching means and is operative to apply an extension force, which is in the opposite direction to the drawing force, to the latch. 
     A switch (not shown) controls the closing of the door via the door opening and closing means from an open position. In operation, starting with the sliding door  300  in an open position allowing access to the interior of the vehicle  310  from outside the vehicle  310 , the door closing switch is closed and a signal is communicated to the opening and closing means to move the door  300  to a nominally-closed position. As will be understood by those skilled in the art, the signal to close may be effected via a microcontroller (not shown) with which the door closing switch is in operative connection. Alternatively, the switch may be included within the microprocessor and the closing action initiated with the closing of a single switch in a passenger compartment of the vehicle or from a hand-held wireless device such as a remote control. 
     Upon reaching a nominally-closed position, P N , the sliding door  300  rests on the door seal, nominally applying a compressing force C N  to the seal. The door  300  is nominally separated from the door frame at a separation distance S N . The latching means causes the latch to engage with the catch. In this configuration, the sliding door  300  is latched, but the door seal is not yet significantly compressed. As will be appreciated by those skilled in the art, it is desirable not to provide power to the door opening and closing means sufficient to drive the door  300  into a fully-closed and latched position, P F , by itself. This can be, for example, because the sliding door opening and closing means cannot provide the force required. Therefore, the door latching means is operative to urge the door into the fully-closed position, P F . As will be further appreciated by those skilled in the art, signals transmitted to the door latching means may also be effected via a microcontroller (not shown). As will be still further appreciated by those skilled in the art, the entire opening or closing step herein described may be initiated by a single physical switch and further switching effected by the microcontroller. 
     When the sliding door latching means urges the door  300  toward the fully-closed position, P F , from the nominally-closed position P N  the latch, starting in an extended position, is drawn in a closing direction by the latch actuator. As the latch is moved, it thereby draws the attached door from the nominally-closed position, P N  to the fully-closed and latched position, P F , where the door seal is further compressed to C F  and the door  300  is separated from the door frame at a separation distance S F . The fully-compressed seal, C F , and door position, P F , is the condition in which the door seal is compressed and maintained when the vehicle is in a condition to be driven. As will be appreciated by those skilled in the art, C F  is greater than C N  (greater compression force when fully closed) and S N  is greater than S F  (smaller gap when fully closed). 
     When it is desired to open the sliding door  300 , the first switch is closed and the door opening and closing means urges the door  300  from the fully-closed position with a separation distance of S F  and a seal compression of C F  to an over-closed position, P O , with a separation distance of S O  and a seal compression of C O . The over-closed position, P O , is accomplished by displacing the door  300  to a closed position beyond the fully-closed position, P F , to compress the door seal beyond the full-compressed state, C F . As will be appreciated by those skilled in the art, C O  is greater than C F  and S F  is greater than S O . Once the over-closed position, P O , is accomplished the latch is released, such as by displacing the latch laterally in a conventional manner to release the catch. At this point, the sliding door has been moved beyond the fully-closed position, P F , thereby releasing or reducing tension on the latch from the elastic force of the compressed door seal. Thus, when a signal from the second switch causes the latch to disengage from the catch, the undesirably loud “pop” or “snap” traditionally associated with such disengagement is reduced or eliminated. Additionally, the door  300  does not make an uneven or abrupt motion. Once the latch is disengaged, the door  300  may then be opened by the door opening and closing means, upon activation of the third switch as described above, which is a smooth motion. Thus, the step of over-compressing the door seal prior to disengagement of the latch eliminates or significantly reduces the audible and visible result of the sudden release of the potential energy of the compressed door seal. The potential energy is instead released more gradually by the sliding door opening and closing means releasing the compressive force on the door seal. 
     This detailed description in connection with the drawings is intended principally as a description of the presently preferred and exemplary embodiments of the invention, and is not intended to represent the only form in which the present invention may be constructed or utilized. The description sets forth the designs, functions, means, and methods of implementing the invention in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and features may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention and that various modifications may be adopted without departing from the invention or scope of the following claims.