Patent Publication Number: US-6338508-B1

Title: Motor-vehicle latch system with power open

Description:
FIELD OF THE INVENTION 
     The present invention relates to a motor-vehicle latch system. More particularly this invention concerns such a system which has actuators in the latch and a central controller for power opening any of the latches. 
     BACKGROUND OF THE INVENTION 
     In a standard motor-vehicle central-lock system all of the door latches, even any latches of the trunk or gas-filler cover, are operated by a central controller and can each be moved between a latched position holding the respective door or lid closed and an unlatched position allowing it to open. Each passenger or driver door latch also normally has an outside operating handle and can also be moved between an unlocked position in which actuation of the respective outside handle shifts the latch into the unlatched position and a locked position in which actuation of the outside handle does nothing. Furthermore each latch normally comprises a fork engageable around a bolt extending from the door post, a pawl that can retain the fork in a position engaged around the door bolt and that can release the fork to allow the door to open. This fork/pawl structure is operated through a main locking lever shiftable between the above-described locked and unlocked positions by means of a respective small electrical drive operated by the central controller. 
     The controller can in turn be triggered by an operator normally carried by the driver. In the most sophisticated keyless-entry systems, the driver simply carries a small transponder that communicates with the controller to unlock the latches as the driver approaches his or her vehicle. Similarly the operator could be a standard push-button remote or a smart card. It could even be a standard edge-bitted key. 
     As described in EP 0,896,113 of Hochart and Girard the drive of each latch can also directly or indirectly move the latch from the latched to the unlatched position. To this end a release lever has an edge that coacts with a pin on the fork-retaining pawl. Pivoting the release lever requires considerable torque, so the drive motor for the latch must be fairly powerful. This largely loses the advantage of the standard central-system latches where a relatively small motor is used to move between the locked and unlocked positions. 
     In U.S. Pat. No. 5,802,894 of Jahrsetz a central control system for the door latches of a motor vehicle has a central unit connected to the door latches via a control line and the door latches each have a first electrically-operable actuator and a second electrically-operable actuator together enabling the “operate”, “locked and unlocked”, “antitheft mode on and off” and “child-safety mode on and off” operations. The door latches can be mechanically identical and can have a keeper pawl controlled both by the first actuator and an interior lever which is effective only when the second operator has displaced a lever from its ineffective position into an effective position. 
     These central lock systems which employ the drive in the latch to effect the unlatching movement have the considerable disadvantage that, if the vehicle power fails, the doors cannot be opened from inside or out unless they have, in addition to the motor-powered actuation, a complete mechanical linkage. The alternative to providing such a redundant mechanical linkage is a redundant power supply which is not normally considered a reasonable option. 
     OBJECTS OF THE INVENTION 
     It is therefore an object of the present invention to provide an improved door latch for a central motor-vehicle latch system. 
     Another object is the provision of such an improved door latch for a central motor-vehicle latch system which overcomes the above-given disadvantages, that is which is of relatively simple construction but which can be locked and unlocked and latched and unlatched both by an individual mechanical linkage and an individual motor drive. 
     The invention is aimed at producing such a lock which, in spite of parallel powered and mechanical systems, is of simple and inexpensive construction. 
     SUMMARY OF THE INVENTION 
     A door latch for a motor-vehicle central-latch system having a central electronic controller and an operator for the controller latch has according to the invention a housing, a locking element displaceable on the housing between a position holding a door bolt and a position releasing the door bolt, and a pawl displaceable on the housing between a retaining position holding the locking element in its bolt-holding position and a freeing position allowing the locking element to assume its bolt-releasing position. A release lever pivotal on the housing into an actuated position can put the pawl into the freeing position and an outside operating lever is pivotal on the housing between actuated and unactuated positions. A main locking lever is pivotal on the housing between locked and unlocked positions. An electric motor in the housing can displace the main locking lever between its locked and unlocked positions. A link engageable between the main locking lever, the outside operating lever, and the release lever serves for, when the main locking lever is in the unlocked position and the outside operating lever is in its unactuated position, coupling the outside operating lever to the release lever to displace same into its freeing position on movement of the outside operating lever into its actuated position. When the main locking lever is in the locked position and the outside operating lever is in its actuated position, the link displaces the release lever into its freeing position on movement of the main locking lever into its unlocked position. Normally the link, when the main locking lever holds in the locked position, decouples the outside locking lever from the release lever. 
     Thus with this system the drive motor can function, as is standard, to switch the latch between its locked and unlocked conditions. In the locked position actuation of the outside operating handle is not transmitted to the release lever by the link. According to the invention, however, if the drive motor attempts to move the locking lever into the unlocked position while the outside operating lever is actuated, the locking lever is effectively coupled to or acts on the release lever to trip it and unlatch the latch. Thus the same drive motor can serve both to lock and unlock the latch and to unlatch it. It is not necessary to provide a second drive motor for the unlatching function. 
     The drive in accordance with the invention includes a worm mounted on the drive motor, a worm wheel meshing with the worm, and an eccentric on the worm wheel engageable with the main locking lever. The main locking lever has a forked end formed with a recess in which the eccentric is engageable. Of course the release lever can also be actuated directly by means of an inside door handle, and the main locking lever can also be directly actuated by means of an inside lock button or the like. 
     The main locking lever and release lever are formed according to the invention with crossing slots and the link is engaged in both of the slots. More particularly the link is a pin engaged through both of the slots and provided with a retaining disk between the main locking and release levers. Alternately as shown in above-cited U.S. Pat. No. 5,802,894, the link can be a lever pivoted on the latch. 
     The outside operating lever is pivotal on the housing about an axis parallel to axes of rotation of the main locking and release levers. In addition the outside operating lever has an angled cam edge engageable with the link in the actuated position of the outside operating lever on movement of the main locking lever from the locked position to the unlocked position. Thus as the link pin is moved by the main locking lever while engaged in the slot of the release lever, it is cammed to the side to actuate the release lever. The travel along the cam edge can be relatively long for considerable mechanical advantage so a relatively weak drive motor can be used. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which: 
     FIG. 1 is a schematic diagram illustrating a latch system according to the invention; 
     FIG. 2 is a side view of one of the latches of the system; 
     FIG. 3 is an opposite side view of the latch in the unlocked and unactuated position; 
     FIG. 4 is a view like FIG. 3 in the locked and unactuated position; 
     FIG. 5 is a view like FIG. 3 in the actuated and unlocked position; and 
     FIG. 6 is a section taken along line VI—VI of FIG.  1 . 
    
    
     SPECIFIC DESCRIPTION 
     As seen in FIG. 1 a central electronic controller  1  is connected to a plurality of identical power door latches  2 , where one for each of four doors, via a serial-bus line  3  with a multiplexer and demultiplexer as described in above-cited U.S. Pat. No. 5,802,894. Each latch  2  includes its own operating circuit  4  that in turn controls an electrical drive  5  that serves for displacing the latch  2  between locked and unlocked conditions and that can actually unlatch the latch under certain conditions. The controller  1  coacts with an operator  6  that can be a remote transmitter, a smart card, a transponder, or a simple key. In a standard system it is a transponder carried by the user and capable of being sensed when in close proximity to the vehicle having the latches  2  and controller  1 . Thus the user carrying the operator  6  is detected as he or she approaches the vehicle and as described below the controller  1  unlocks all the latches  2  and even unlatches any latch  2  that is being actuated. The operator serves for identifying the person carrying it, by a comparison between an identity code word stored in the controller and an identity code word outputted by or read from the transponder. A passive system such as in German 197 01 077 is also usable. 
     FIGS. 2 and 6 show how one of the latches  2  has a housing  9  comprised of a body  10  and a cover  11  carrying a fork  7  pivotal on a shaft  28  and securable by a pawl  8  about a door-post bolt  34 . An inside locking lever  12  operable by a door button  35  and an inside latching or operating lever  13  operated by an inside handle  36  are both mounted on the inside face of the housing  9 . 
     Inside the housing  9  a main locking lever  14  is pivotal on the fork pivot  28  adjacent a worm wheel  15 . The drive  5  comprises a reversible electric motor  5   a  having an output shaft  5   b  carrying a worm  5   c  meshing with the wheel  15 . This wheel  15  in turn carries a pair of diametrically opposite eccentric pins  16 ′ and  16 ″ that serve to pivot the locking lever  14  between the unlocked positions shown in FIGS. 3 and 5 and the locked position of FIG.  4 . To this end the lever  14  has an end cutout  17  flanked by a pair of cam surfaces  18 ′ and  18 ″ that can be positioned to extend radial of the axis  15 A of the wheel  15 . 
     An outside locking lever  19  is connected to the main locking lever  14  by a lost-motion coupling constituted by a narrow tab  20  on the lever  19  projecting into a wide cutout  21  in the lever  14 . This lever  19  is normally operated by an outside key cylinder  38  as shown in FIG.  3 . In addition an outside operating or latching lever  22  is pivoted at  23  on the housing  9  and has one arm  22   a  connected to an outside door handle  37  and an opposite arm  22   b  forming a pair of cam surfaces  33 ′ and  33 ″. 
     A release lever  24  pivoted on the housing body  10  at  25  is formed with a nose  26  that can engage a tab  27  projecting from the pawl  8  through the housing body  10 . When the lever  24  is rocked counterclockwise as seen in FIGS. 3 to  5  about its pivot  25 , the nose  26  engages and presses down on the tab  27  and pushes the pawl  8  against the force of an unillustrated torque spring out of engagement with the fork  7  so it can pivot clockwise as shown in FIG. 2 to release the bolt  34  and unlatch the respective door. The pivots  23 ,  25 , and  28  are all parallel to each other and to the rotation axis  15 A. 
     While the inside handle  36  can be coupled permanently via the lever  13  with the release lever  24 , the outside handle  37  and its lever  22  are coupled via a link pin  30  with the lever  24 . To this end the main locking lever  14  is formed with a straight elongated slot  31  extending generally radially of its pivot  28  and the release lever  24  is formed with another such elongated slot  32  extending generally radially from its pivot  25  and transverse to the slot  31 . The pin  30  extends through both slots  31  and  32  and is fitted with a snap ring or washer  29  between the levers  14  and  24 . This pin  30  can engage cam surfaces  33 ′ and  33 ″ on the arm  22   b  of the lever  22 . 
     The latch described above operates as follows: 
     When unlocked as shown in FIG. 3 the pin  30  is in position A engaging the upper cam edge  33 ″ which extends generally radially from the pivot  23 . If the outside handle  37  is operated to pivot the lever  22  clockwise, this edge  33 ″ will push the pin  30  to the left, into position B of FIG. 5, thereby causing the nose  26  to push down on the tab  25  and disengage the pawl  8  from the fork  7 . 
     Similarly, starting from the unlocked position, the drive  5  can rotate the wheel  15  counterclockwise so the pin  16 ″ engages in the cutout  17  and rotates the main locking lever  14  clockwise until the other pin  16 ′ comes to rest on the surface  18 ′ as shown in FIG.  4 . This will cause the lever  14  to push the pin  30  down in the slot  32  to position C shown in FIG.  4 . Actuation of the lever  22  in this position will have no effect, since the edges  33 ′ and  33 ″ will move past the pin  30  without touching it. The door thus is locked. 
     From the locked position of FIG. 4, opposite clockwise rotation of the wheel will oppositely rock the lever  14  and move it back into the unlocked position. 
     In addition from the locked position of FIG. 4, if the outside handle  37  is actuated before the operator  6  initiates unlocking of the latches, the drive  5  can release the fork  8  without the driver having to reactuate the handle  37  or operator  6 . This is done as shown in FIG. 5, where the lever  22  is shown in the actuated position, by the drive  5  pivoting the main locking lever  14  counterclockwise so the slot  31  raises the pin  30  along the slot  32 . As the pin  30  moves up toward the pivot  23 , it first contacts the angled outer cam surface  33 ′, forcing it toward the pivot  28  and thereby pivoting the release lever  24  counterclockwise about its pivot  25  and freeing the fork  7 . Thus a user equipped with, for instance, a transponder  6  that is sensed by the controller  1  will always be able to open a door. If he or she actuates the handle  37  before the drive  5  has had time to move the latch  2  to the unlocked (FIG. 3) position or the operator  6  has been actuated, movement into this position will automatically unlatch the latch  2  without the user having to reactuate the handle  37 .