Patent Publication Number: US-2004055407-A1

Title: Actuator assembly

Description:
[0001] This application claims priority to Great Britain Patent Application GB 0217665.9 filed on Jul. 31, 2002.  
       BACKGROUND OF THE INVENTION  
       [0002] The present invention relates to an actuator assembly used to release or latch vehicle door latches that includes an energy storing member that assists movement of an output member and provides a force that acts substantially through a pivot point of the output member when in a rest position.  
       [0003] Known actuator assemblies used in vehicle door latches are only required to provide an output in one direction when actuating. The actuator assembly is returned to a rest position by powering an actuator assembly motor in a reverse return direction. This return stoke does no work.  
       [0004] Copending application EP1128006 discloses a system which exploits the fact that the return stroke can be used to do work and includes a form of energy storage member. This disclosed storage member is a spring, arranged to store energy when the actuator is moving in a return direction, and to assist the actuator when moving in the actuation direction. This allows the actuator to produce a higher output force in the actuation direction, or indeed allow a smaller actuator motor to be used for the same output force.  
       [0005] However, a problem with such an actuator assembly is that once the energy has been stored in the spring, some form of retaining member is required to releasably retain the actuator in the rest position, thereby preventing the spring from driving the actuator in the actuation direction when actuation is not required.  
       [0006] This problem is overcome in EP1128006 by using a retaining member, such as a clutch or detent arrangement, arranged in the actuator assembly to prevent the spring from driving the actuator. However, this requires the actuator assembly to include additional components and adds to the complexity of the assembly.  
       [0007] In some situations, the friction associated with the actuator assembly itself and/or the friction associated with the components to be actuated is sufficient to overcome the energy stored in the spring, and therefore prevent the spring from driving the actuator in the actuation direction. However, relying on such friction tends to limit the force of the spring which can be used.  
       SUMMARY OF THE INVENTION  
       [0008] An object of the present invention is to provide an actuator assembly which is powered in an actuation direction and in a return direction (to store energy in an energy storage member) which is less complex.  
       [0009] According to the present invention, an actuator assembly includes an actuator drivingly connected by a transmission path to an output member. The actuator is capable of moving the output member about a pivot point in a first direction from a rest position to an actuated position. The actuator is also capable of moving the output member in a second direction from the actuated position to the rest position. The actuator assembly further includes an energy storing member which provides a force. Movement of the output member by the actuator in the first direction is assisted by the energy storing member, and movement of the output member by the actuator in the second direction stores energy in the energy storing member. The energy storing member is positioned relative to the pivot point such that in the rest position, the force acts substantially through the pivot point and does not generate any substantial resultant torque on the output member.  
       [0010] Advantageously, since there is no resultant torque acting on the output member, the output member remains in the rest position and therefore prevents the energy storing member from driving the actuator until actuation is required.  
       [0011] According to another aspect of the present invention, the actuator assembly includes an actuator drivingly connected by a transmission path to an output member. The actuator is capable of moving the output member about a pivot point in a first direction from a rest position to an actuated position. The actuator is also capable of moving the output member in a second direction from the actuated position to the rest position. The actuator assembly further includes an energy storing member which provides a force. Movement of the output member by the actuator in the first direction is assisted by the energy storing member over a substantial portion of the movement to the actuated position. Movement of the output member by the actuator in the second direction stores energy in the energy storing member over a substantial portion of the movement to the rest position. The energy storing member is positioned relative to the pivot point such that in the rest position, the force acts to drive the output member in the second direction.  
       [0012] Advantageously, this means that in the rest position, the energy storing member drives the actuator in the second direction, and therefore prevents the energy storing member from driving the actuator until actuation is required.  
       [0013] These and other features of the present invention will be best understood from the following specification and drawings.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0014] The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:  
     [0015]FIG. 1 shows the actuator assembly of the present invention with the actuator in a rest position;  
     [0016]FIG. 2 shows the actuator assembly of FIG. 1 with the actuator in an actuated position;  
     [0017]FIG. 3 shows an alternative actuator assembly with the actuator in a rest position;  
     [0018]FIG. 3A shows the actuator assembly of FIG. 3 with the actuator in an actuated position;  
     [0019]FIG. 4 shows an elevated view of parts of a latch assembly according to the present invention with a claw at an outer first safety position;  
     [0020]FIG. 5 shows an opposite side view of the latch assembly of FIG. 4;  
     [0021]FIG. 6 shows an elevated view of the latch assembly of FIG. 4 with the claw driven to an inner door fully closed position;  
     [0022]FIG. 7 shows an opposite side view of the latch assembly showing unlatching with disablement of a drive pawl; and  
     [0023]FIG. 8 shows a view of an alternate latch assembly.  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0024] With reference to FIG. 1, there is shown an actuator assembly  10  including a housing  13  (only part of which is shown), an actuator in the form of an electric motor  12 , an output member in the form of a worm wheel  16 , and an energy storing member in the form of a helical spring  18 .  
     [0025] The worm wheel  16  is rotationally mounted on the housing  13  at a pivot  28  and includes an abutment in the form of a crank pin  30 . A pin  23  mounted on the worm wheel  16  can be connected, via a suitable linkage (not shown in FIG. 1), to a device which is to be actuated.  
     [0026] The helical spring  18  is mounted on the housing  13  and has a circular portion  26  that includes several coils mounted on a boss  26 A of the housing  13 . The spring  18  also includes a first arm  20  and a second arm  22 . The first arm  20  abuts against the crank pin  30 , and the second arm  22  abuts against a fixed abutment  24  is mounted on the housing  13 . The spring  18  thus acts to bias the crank pin  30  away from fixed abutment  24 .  
     [0027] The electric motor  12  is drivingly connected to the worm wheel  16  by a worm gear  17 . The worm gear  17  is mounted rotationally fast on an electric motor shaft  15  and engages with the worm wheel  16  via gear teeth (not shown). As shown in FIG. 1, the worm gear  17  and the electric motor shaft  15  form a transmission path  14  between the electric motor  12  and the worm wheel  16 , such that actuation of the electric motor  12  causes the worm wheel  16  to rotate about the pivot  28 .  
     [0028] The actuator assembly  10  preferably includes a stop means (not shown) operable to prevent movement of the worm wheel  16  counter-clockwise past the position shown in FIG. 1. The actuator assembly  10  also preferably includes a further stop means (not shown) operable to prevent movement of the worm wheel  16  clockwise past the position shown in FIG. 2.  
     [0029]FIG. 1 shows the actuator assembly  10  in a rest position with the helical spring  18  wound up (see below). With the crank pin  30  in position A, the first arm  20  generates a force F which acts on the crank pin  30  in a direction which acts through the pivot  28 . Thus, the force generated by the helical spring  18  does not generate a resultant torque on the worm wheel  16 .  
     [0030] It will be appreciated that when the force acts substantially through the pivot  28 , the actuator assembly  10  will remain stationary. This is independent of any friction forces associated with the actuator or friction forces associated with the components to be actuated.  
     [0031] When actuation is required, an electrical current is supplied to the motor  12 , rotating the shaft  15  and consequently the worm wheel  16  in a first actuating direction (clockwise when viewing FIG. 1) towards the actuated position of FIG. 2. As the worm wheel  16  rotates, the crank pin  30  moves in the first direction from position A of FIG. 1 to position C of FIG. 2. This movement is assisted by the force provided by the helical spring  18  which acts on the crank pin  30  and therefore on the worm wheel  16 .  
     [0032] Once actuation has occurred, an electrical current is supplied to the motor  12 , causing it to run in a reverse direction, and results in the worm wheel  16  rotating in a second return direction (counter-clockwise direction when viewing FIG. 2) towards the rest position of FIG. 1. This results in the crank pin  30  moving from position C of FIG. 2 to position A of FIG. 1. It will be appreciated that as the worm wheel  16  moves in the second direction, it works against the helical spring  18  which is being acted on by the crank pin  30 , causing the helical spring  18  to wind up.  
     [0033] Thus, when the actuator assembly is  10  moving in the first actuating direction from the rest position to the actuated position, the helical spring  18  is unwinding and thus releasing energy previously stored, assisting the motor  12 . When the actuator assembly  10  moves in the second return direction from the actuated position to the rest position, the motor  12  acts to wind up, and therefore store energy in, the helical spring  18 .  
     [0034] It will be appreciated that as the worm wheel  16  rotates in the first direction, the crank pin  30  will first slide along the arm  20  towards the circular portion  26  of the helical spring  18  before reaching its closest position. The crank pin  30  will then slide back along the arm  20  away from the circular portion  26 .  
     [0035] In a further embodiment, the arm  22  can be locally fixed to the abutment  24  to prevent sliding. Similarly, the arm  20  can be locally fixed to the pin  30  to prevent sliding. Under these circumstances, the boss  26 A can be dispensed with to allow the circular portion  26  to float in space, as determined by the movement of the arms  22  and  20 .  
     [0036] Once the actuator assembly  10  returns to the rest position by the motor  12  as shown in FIG. 1, the helical spring  18  acts on the crank pin  30 . However, as described above, the force acting on the crank pin  30  acts substantially through the pivot  28 , and thus the actuator assembly  10  remains in the rest position until further current is supplied to the motor  12 .  
     [0037] Even though the spring  18  unwinds when moving from the position shown in FIG. 1 to the position shown in FIG. 2, depending upon the geometry and spring rate, the torque applied to worm wheel  16  by the spring  18  can be arranged to start at zero, increase to a maximum and then decrease (in some cases back to zero) as the actuator assembly  10  moves from the rest position to the actuated position. This has the advantage that the actuator assembly  10  only has to produce a relatively low torque when starting to return. The higher torque is only required on the return strokes once the motor  12  is in motion.  
     [0038]FIG. 1 also shows a second embodiment, where the crank pin  30  is shown in a rest position B. In this case, the preferred stop means (not shown, but mentioned above) would be repositioned to allow the worm wheel  16  to rotate this far counterclockwise.  
     [0039] The operation of the second embodiment of the actuator assembly  10  differs from the first embodiment since, in the rest position, the force acting on the crank pin  30  does not act substantially through the pivot  28 , but is sufficiently offset from the pivot  28  to generate a relatively low torque on the worm wheel  16  and drive the worm wheel  16  in the second return direction against the stop.  
     [0040] As the worm wheel  16  is driven by the motor  12  in the first direction from the rest position (position B), the crank pin  30  first passes through position A before reaching the actuated position (position C) shown in FIG. 2. Therefore, from position B to position A, the motor  12  is storing energy in the helical spring  18 , whereas from position A to position C, the motor  12  is assisted by the helical spring  18 . It should be noted that the angle that the arm  20  rotates between position B and position A is relatively small and hence only a relatively small amount of energy is stored in the spring  18  when the crank pin  30  moves from position B to position A. However, the spring  18  is significantly unwound when the crank pin  30  moves from position A to position C, thus releasing significant amounts of stored energy to assist the motor  12 .  
     [0041] Thus, whether the crank pin  30  is stopped at position A (first embodiment) or position B (second embodiment), the helical spring  18  provides a force which either does not generate any substantial resultant torque on the worm wheel  16  (position A), or drives the worm wheel  16  in the second return direction (position B). Therefore, the worm wheel  16  is prevented from driving the motor in the first actuating direction unless actuated.  
     [0042] With reference to FIGS. 3 and 3A, there is shown an alternate actuator assembly  110 . Corresponding features from the first and second embodiments of FIG. 1 are numbered 100 greater. In this case, the output member is in the form of an output lever  119 . The worm wheel  116  has wheel teeth  113  and is rotatably mounted on a chassis (not shown) at a pivot  128 . The worm gear  117  has gear teeth  141 . The worm gear  117  is mounted on a shaft  115  of a motor  112  and is positioned such that gear teeth  141  engage with the wheel teeth  113 , thereby drivingly connecting the worm gear  117  and the worm wheel  116 . The worm wheel  116  has a wheel  145  with teeth  147  which is located on the pivot  128 . The wheel  145  has a smaller diameter and is rotationally fast with the worm wheel  116 .  
     [0043] An output lever  119  is rotatably mounted on the chassis at a pivot  125 . The output lever  119  has a quadrant portion  149  having teeth  127  located on an outer surface. A detent  130  is also located on the quadrant portion  149 . The output lever  119  further includes a lower portion  121  upon which a pin  123  is mounted. The output lever  119  is positioned relative to the wheel  145  such that the teeth  127  engage the teeth  147 , drivingly connecting the worm wheel  116  to the output lever  119 . It can be seen from FIG. 3 that the worm gear  117 , the electromotor shaft  115 , and the worm wheel  116  form a transmission path  114  between the motor  112  and the output lever  119 . Actuation of the motor  112  causes the output lever  119  to rotate about the pivot  125 .  
     [0044]FIG. 3 shows the actuator assembly  110  in a rest position with the helical spring  118  wound up. With the detent  130  in position A, the first arm  120  generates a force F on the detent  130  which acts through the pivot  125  of the output lever  119 . Thus, as in the embodiment of FIG. 1, the force generated by the helical spring  118  does not generate a resulting torque on the output lever  119 .  
     [0045] When actuation is required, an electrical current supplied to the motor  112  rotates the shaft  115 . Consequently, the worm wheel  116  rotates in a counterclockwise direction, causing the output lever  119  to move in a first direction (clockwise when viewing FIG. 3) towards the actuated position of FIG. 3A. As the output lever  119  rotates, the detent  130  moves in the first direction from position A of FIG. 3 to position C of FIG. 3A. The movement is assisted by the force provided by the helical spring  118  which acts on the detent  130  and therefore the output lever  119 .  
     [0046] Once actuation has occurred, an electrical current is supplied to the motor  112 , causing it to run in a reverse direction, rotating the worm wheel  116  in a clockwise direction. This causes the output lever  119  to move in a counter-clockwise (second return) direction towards the rest position of FIG. 3. As the output lever  119  rotates counter-clockwise, it works against the helical spring  118  acted on by the detent  130 , causing the helical spring  118  to wind up.  
     [0047] Thus, as in the first embodiment, when the actuator assembly  110  is moving in the first actuating direction from the rest position to the actuated position the helical spring  118  unwinds and releases energy previously stored to assist the motor  112 . When the actuator assembly  110  moves in the second return direction from the actuated position to the rest position, the motor  112  acts to wind up, and therefore store energy in, the helical spring  118 .  
     [0048] Once the actuator assembly  110  returns to the rest position by the motor  112 , as shown in FIG. 3, the helical spring  118  acts on the detent  130 . However, as described above, the force acting on the detent  130  acts substantially through the pivot  125 , and thus the actuator assembly  110  remains in the rest position until further current is supplied to the motor  112 .  
     [0049] In an alternate embodiment, the detent  130  can be arranged on the output lever  119 . In the rest position, the force acting on detent  130  does not act through the pivot  125 , but acts sufficiently offset from the pivot  125  to generate a relatively low torque on the output lever  119  and drive the worm wheel  116  in the second return direction (in a manner similar to the second embodiment).  
     [0050] The actuator assemblies  10  and  110  described in FIGS.  1  to  3 A can be used to move a component of an associated device, such as a component of a vehicle door latch assembly to change the state of the latch.  
     [0051] A typical latch can achieve various states, for example unlocked (can be unlatched by operation of an inside or outside handle), locked (can be unlatched by operation of an inside handle but not an outside handle), latch bolt fully released (door open), latch bolt fully latched (door fully closed), latch bolt in a first safety position (a door ajar position between fully latched and released where a striker is still retained by a latch bolt), superlocked (cannot be unlatched by operation of inside handle or outside handle), and child safety on (operation of an inside door handle does not unlatch the latch, and operation of the outside handle may or may not unlatch the latch depending upon whether the door is locked or unlocked).  
     [0052] It will be appreciated that some of these latch states are mutually exclusive. For example, a latch cannot be both unlocked and superlocked. However, other latch states can exist simultaneously. For example, a latch can be child safety on and locked. Similarly, a latch can be child safety on and unlocked.  
     [0053] A known prior art latch is described in copending PCT application WO98/531565 which relates to power closing a vehicle door latch. Actuator assemblies according to the present invention can be used with this power closable latch as described in detail below.  
     [0054]FIGS. 4 and 5 illustrate a latch assembly  250 , which will be operatively secured in a door (not shown) in a known manner. The latch assembly  250  includes a conventional rotating latch claw  210  having a mouth  212 . The mouth  212  coacts with a striker  214  operatively mounted to the associated door post (not shown) and the actuator assembly  10  of FIGS. 1 and 2. In those Figures, the claw  210  is shown at an outer position at which it is engaged by the striker  214  as the door closed to a first safety position. In the first safety position, the door is still slightly ajar, with little or no compression of its weather seals, turning the claw  210  counter-clockwise.  
     [0055] A latching pawl  216  self-engages a ratchet tooth  218  formed as a notch in the upper claw  210  periphery to retain the claw  210 . An unlatching member, operated by the door handles (not shown), is of generally conventional construction and includes a release lever  220  selectively shiftable to free the pawl  216  from the claw  210  when the door is to be opened.  
     [0056] The power closing mechanism of the latch assembly  250  includes a drive input lever  222  pivoted co-axially with the claw  210  that carries a drive pawl  224  pivoted on a leftwardly projecting arm  226  of the drive input lever  222 . In FIGS. 4 and 5, the drive input lever  222  is shown at the rest position with the arm  26  raised. In this position, the drive pawl  224  is held clear of the claw  210  periphery by a back-stop pin  228  (mounted on a chassis  229  of the latch assembly  250 ) which abuts a projection on the upper edge of the drive pawl  224 .  
     [0057] The distal end of the projecting arm  226  is connected by a vertical pull cable  230  to the actuator assembly  10 . The cable  230  is attached to the pin  23  on the worm wheel  16  of the actuator assembly  10 .  
     [0058] In operation, after the door is opened to let passengers in or out of the vehicle, the door is either manually pulled or pushed towards a closed position, and the claw  210  mounted on the door approaches the striker  214 . When the door moves to the first safety position with the claw  210  in the outer position of FIG. 4, the switching logic of the actuator assembly  10  energizes the actuator automatically after a time delay. The worm wheel  16  is driven in a first direction, and hence drives the projecting arm  226  downwards to the position shown in FIG. 6. As the drive input lever  222  turns clockwise, the drive pawl  224  is carried towards the claw  210  periphery, spacing the drive pawl  228  from the back-stop pin  228 . The drive pawl  228  is free to self engage with a drive ratchet tooth  232  in the lower edge of the claw  210 , driving the claw  210  further counter-clockwise to the inner position of FIG. 6. Thus, the claw  210  co-acts with the striker  214  to drive the door to the fully closed position, compressing the weather seals.  
     [0059] The latching pawl  216  engages the left hand top edge of the mouth  212  of the claw  210 , serving as a further ratchet tooth  234  to secure the door closed in conventional manner.  
     [0060] Thus, it can be seen that moving the actuator in a first direction moves the drive pawl from  224  a first position where the latch is in a first state (first safety position) to a second position where the latch is in a fully closed state.  
     [0061] As soon as the drive input lever  222  has completed its downward power stroke, i.e. almost immediately after actuation, the electrical circuit restores the drive unit to its rest condition. The drive input lever  222  is returned to the rest position as shown in FIG. 4, with the back-stop pin  228  ensuring that the drive pawl  224  is again disengaged from the claw  210  to allow for subsequent opening of the door.  
     [0062] To open the door, the latching pawl  216  is shifted in a known manner by operation of a release lever  220 , freeing the claw  210  to turn clockwise as the door is pushed open.  
     [0063] To ensure that the door can be opened if the power should fail or there is an electrical malfunction, the assembly further includes a disabling system. As shown in FIG. 5, the projecting arm  226  mounts a rocker lever  236 , one arm of which is coextensive with the drive pawl  224  and which projects above a rearwardly extending pin  238  on the drive pawl  224 . In normal operation, as described above, the pin  238  does not contact the rocker lever  236 . The left hand tail  240  of the rocker lever  236  is connected to an arm of the release lever  220  by a rigid vertical link  242 .  
     [0064] If the door is closed, i.e. the mechanism is in the FIG. 6 condition, but the input lever  222  fails to return to the rest position, the drive pawl  224  remains engaged with the tooth  232  and obstructs clockwise rotation of the claw  210  for opening the door. However, when the release lever  220  is operated to disengage the latching pawl  216 , the link  242  is drawn up, rotating the rocker lever  236  to the position of FIG. 7 and depressing the pin  238  to ensure that the drive pawl  224  is disengaged from the claw  210 .  
     [0065] As the motor  12  power closes the latch, the motor  12  is assisted by the spring  18 . As the motor  12  returns to the rest position, the motor  12  works against and stores energy in the spring  18 . Thus, it is possible to use a lower output motor  12  to power close the latch when using the actuator assembly  10  of the present invention by utilizing the energy stored in the spring  18  when the motor  12  returns to the rest position.  
     [0066] In another embodiment, the latch of FIGS.  4  to  7  can be power latched by using the actuator assembly  110  of FIGS. 3 and 4 by connecting the pin  123  of the output lever  119  to the cable  230 .  
     [0067] The principle of operation of the latch assembly  250  is that the door is manually moved to the first safety position, and then electrically moved to the fully closed position. However, in principle, it is possible to provide a power closing latch wherein the door is manually moved to a position which is not a first safety position. Thus, the door might be manually moved to an “initial engagement state”, typically as a striker  214  comes into initial engagement with a claw  210 , or initially enters the mouth  212  of a claw  210 . The latch would then be power closed from this initial engagement state to the fully closed state.  
     [0068] In other embodiments, the initial engagement state could be detected by a sensing means (such as micro switches) which detects a predetermined position of the door relative to the latch.  
     [0069] Actuator assemblies  10 ,  110  according to the present invention can also be used to power unlatch latches. FIG. 8 illustrates a power unlatching latch assembly  350 . The latch assembly  350  of FIG. 8 includes a rotating latch claw  310  having a mouth  312  for coacting with a striker  314  which is mounted on a door post (not shown). The claw  310  has a fully closed abutment surface  333  and a first safety abutment surface  382 .  
     [0070] The claw  310  is biased by a claw spring (not shown) in a clockwise direction. A pawl tooth  381  of a pawl  316  self engages with the claw  310  to releasably retain the claw  310  in a closed position. The pawl  316  is mounted on a latch chassis  360  at a pivot  380 , and the claw  310  is mounted on the latch chassis at a pivot  370 . A pin  239  is mounted on the pawl  316 . The latch assembly  350  further includes the actuator assembly  10  of FIGS. 1 and 2. The pin  23  of the actuator assembly  10  is connected to the pin  329  of the pawl  316  via a rod  331 .  
     [0071]FIG. 8 shows the latch in a fully closed state with the pawl  316  in a first position. The pawl tooth  318  is in engagement with the fully closed abutment surface  333  of the claw  310 .  
     [0072] To release the striker (and hence an associated door), operation of an inside or outside door handle (not shown) results in a micro switch (not shown) being actuated. This sends a signal to the actuator assembly  10 , causing the motor  12  to rotate the worm wheel  16  in a first direction, moving the rod  331  to move the pawl  316 , in a clockwise direction and out of engagement with the claw  310 , to a second position. The claw  310  is then free to rotate about a pivot  370 , and movement of the door in an opening direction will result in the claw  310  rotating in a clockwise direction until the striker  314  is disengaged from the claw mouth  312 .  
     [0073] Thus, it can be seen that moving the actuator in a first direction moves the latch pawl  316  from a first position where the latch is in a fully closed state to a second position where the latch is free to open.  
     [0074] Once the latch is open, i.e. once the striker  314  has been released from the mouth  312 , the actuator assembly  10  is almost immediately powered to a rest condition and ready for a subsequent closing of the door. In such a rest condition, the pawl  316  is free to re-engage with the first safety abutment  382  or the closed abutment surface  333 , as will be described below.  
     [0075] Upon closing the door, the claw  310  will initially engage the striker  314 . Further, closing movement of the door will cause the claw  310  to rotate counterclockwise until the claw  310  returns to the fully closed position of FIG. 8. If the door is not fully closed or does not close properly, the claw  310  may not rotate sufficiently to allow engagement of the pawl tooth  381  with the fully closed abutment surface  333 . In these circumstances, the pawl tooth  381  engages with the first safety abutment  382  to prevent the door from inadvertently opening.  
     [0076] Thus, as the motor  12  moves the pawl  316  out of engagement with the claw  310  to release the latch claw  310 , the motor  12  is assisted by the spring  18 . As the motor  12  returns to the rest position, the motor  12  works against and stores energy in the spring  18 . Thus, it is possible to use a lower powered output motor  12  to power release the latch when using the actuator assembly  10  of the present invention by utilizing the energy stored in the spring  18  when the motor  12  returns to the rest position.  
     [0077] In another embodiment, the latch of FIG. 8 is power unlatched by using the actuator assembly  110  of FIGS. 3 and 4 by connecting the pin  123  of the output lever to the pin  329  of the latch pawl  316  using a suitable linkage.  
     [0078] Actuator assemblies according to the present invention can be used with other types of power unlatching latches.  
     [0079] The foregoing description is only exemplary of the principles of the invention. Many modifications and variations of the present invention are possible in light of the above teachings. The preferred embodiments of this invention have been disclosed, however, so that one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.