Abstract:
An actuator including a device for providing a magnetic field including a magnetic field generator, the actuator further including an output element being moveable between a first position where it blocks or breaks an associated mechanical transmission path and a second position where it unblocks or forms part of an associated mechanical transmission path, the output element being moveable as a result of changes in its local magnetic field as generated by the magnetic field generator, at least a part of the device being moveable to change said local magnetic field to effect movement of the output element.

Description:
This application claims priority from United Kingdom patent application GB0018102.4 filed on Jul. 25, 2000. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to actuators, and in particular actuators for latch mechanisms for doors of vehicles. 
     Actuators in latch mechanisms of door are known whereby movement of a cam effects movement of an associated cam follower. However, such arrangements are subject to wear and appropriate cam profiles can be difficult to manufacture. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide an improved form of actuator whereby some or all of the above mentioned problems are obviated. 
     An actuator including a device for providing a magnetic field including a magnetic field generator, the actuator further including an output element being moveable between a first position where it blocks or breaks an associated mechanical transmission path and a second position where it unblocks or forms part of an associated mechanical transmission path, the output element being moveable as a result of changes in its local magnetic field as generated by the magnetic field generator, at least a part of the device being moveable to change said local magnetic field to effect movement of the output element. 
     An actuator including a device for providing a magnetic field including a magnetic field generator the actuator further including an output element being moveable between a first position where it breaks an associated mechanical transmission path and a second position where it forms part of an associated mechanical transmission path, the output element being moveable as a result of changes in its local magnetic field as generated by the magnetic field generator, the device being operable to change said local magnetic field to effect movement of the output element, in which the actuator is caused to move during subsequent operation of an associated transmission path. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows: 
     FIG. 1 is a latch mechanism in a super-locked condition including an actuator according to the present invention; 
     FIG. 1 a  is an enlarged view of part of FIG. 1; 
     FIG. 1 b  is a schematic view in the direction of arrow A of FIG. 1; 
     FIG. 2 is the latch mechanism of FIG. 1 in a locked position with child safety on; 
     FIG. 3 is the latch mechanism of FIG. 1 in an unlocked condition with the child safety on; 
     FIG. 4 is the latch mechanism of FIG. 1 in a locked condition with the child safety off; 
     FIG. 5 is the latch mechanism of FIG. 1 in an unlocked position with the child safety off; 
     FIG. 6 is a latch mechanism of FIG. 1 in a release position; and 
     FIG. 7 is a further schematic embodiment of an actuator according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to FIGS. 1-6 there is shown a latch mechanism  10  including a body  11  which supports various components of the latch mechanism  10  as indicated below. 
     Latch mechanism  10  further includes a claw  12  pivotally mounted about axis  13  on the body  11 . Claw  12  acts to secure an associated door (not shown) in a closed position via a striker pin  14  attached to the door aperture. Rotation of the claw  12  in an anticlockwise direction about axis  13  when viewing FIG. 1 allows release of the striker pin  14 , thus enabling opening of the associated door. 
     The claw  12  is held in a closed position by a pawl  15 , only part of which is shown in dotted profile in FIG. 1 for clarity. Pawl  15  is pivotally mounted on body  11  and can rotate about axis  16 . Claw  12  can be held in a first safety position (not shown) when pawl  15  engages first safety abutment  17 . 
     Pawl lifter  20  is generally flat and lies in a plane parallel to pawl  15 , to which it is rotationally secured. When viewing FIG. 1 pawl  15  is obscured by pawl lifter  20 . Clearly, pawl lifter  20  also rotates about axis  16 . 
     An output element in the form of an inside lock link  21  and a further output element in the form of outside lock link  22  are mounted for movement with the pawl, in this case they are each individually pivoted about respective axes  21   a  and  22   a  on pawl lifter  20 . In this case inside lock link  21  and outside lock link  22  are identical and each have respective north magnetic poles  21   b  and  22   b  and release abutments  21   c  and  22   c.    
     Magnetic field generator  30  is capable of rotating independently from pawl lifter  20  about axis  16 . Magnetic field generator  30  has three sets of south magnetic poles S 1 , S 2  and S 3  and three sets of north magnetic poles N 1 , N 2  and N 3  shown diagrammatically in FIG. 1A for clarity. The magnetic field generator  30  further includes levers  34  and  35  shown schematically which are all rotationally fast with magnetic field generator  30 . Preferably magnetic field generator  30  can at least be rotated to the various positions as described below by a power actuator  100  such as a DC motor or preferably a stepper motor. 
     Outside release lever  40  is pivotally mounted about axis  41  and is connected to an outside door handle. Inside release lever  43  (shown diagrammatically in FIG. 1 b ) is pivotally mounted about axis  44  and is connected to an inside door handle. 
     Operation of a door latch mechanism is as follows. 
     FIG. 1 shows the door latch mechanism in a super lock condition, that is to say operation of the outside release lever  40  or inside release lever  43  does not allow unlatching of the mechanism. In this case north magnetic pole  21   b  has being attracted to south magnetic pole set S 2  and north magnetic pole  22   b  has being attracted towards south magnetic poles set S 3 . In particular it can be seen that if outside release lever  40  were to be operated by being rotated in a clockwise direction about axis  41 , abutment  42  would pass release abutment  22   c  of outside lock link  22  without contact (note that outside release lever  40  is in the same plane as outside lock link  22 ). Similarly inside release lever  43  when operated by being rotated in an anticlockwise direction about axis  44  when viewing FIG. 1 b , would cause abutment  45  to pass release abutment  21   c  of inside lock link  21  (see especially FIG.  1 ). 
     FIG. 2 shows the door latch mechanism  10  in a locked position with the child safety feature on. Magnetic field generator  30  has been rotated in an anticlockwise direction when compared to FIG.  1 . However, the inside lock link  21  and outside lock link  22  are in the same position when compared with FIG. 1 since the north magnetic poles  21   b  and  22   b  are still attracted to respective south magnetic poles sets S 2  and S 3 . As such no change in magnetic field has occurred in a region local to magnetic poles  21   b  and  22   b  and as such no movement of the output element takes place. However, lever  34  has been rotated to a position whereby operation of the inside release lever  43  in an anticlockwise direction when viewing FIG. 1 b  would cause abutment  46  to contact lever  34  and rotate magnetic field generator  30  to the position shown in FIG.  3 . Note this initial operation of inside release lever  43  does not unlatch the mechanism but only operates to unlock the door (see below). This method of being able to override and open a locked door which has the child safety on is especially important in an emergency situation whereby a passer-by can effect access to the inside door handle (e.g. by breaking the door window glass), operate the inside door handle to unlock the door, then operate the outside door handle to open the door and then remove the child from the car. 
     FIG. 3 shows the door latch mechanism  10  in an unlocked condition with the child safety feature on. In this case the magnetic field generator has been rotated sufficiently (either by operating the inside release lever when the magnetic field generator was in the position shown in FIG. 2 or by independent rotation of the magnetic field generator directly e.g. by a power actuator) such that north magnetic pole  21   b  is attracted towards the magnetic field generator but north magnetic pole  22   b  is repelled away from the magnetic field generator resulting in anticlockwise rotation of outside lock link  22 . Thus when outside release lever  40  is operated, abutment  42  contacts release abutment  22   c  causing the pawl lifter  20  as a whole to rotate anticlockwise when viewing FIG.  3  and releasing the pawl  15  and allowing the claw  12  to open. Stop  22   d  limits the anticlockwise rotation of outside lock link  22 . Upon release of the outside release lever  40  the pawl lifter  20  is biased back to the position as shown in FIG. 3 by a spring (not shown). It should also be noted that the inside lock link  21  is in the same position as that shown in FIG. 1, thus operation of the inside release lever  43  does not allow opening of the door. 
     It should be noted that lock link  21  has remained in the same position as shown in FIG.  3  and FIG. 2 since the magnetic field in the region local to the magnetic pole  21   b  has remained unchanged. 
     However, consideration of the magnetic field local to magnetic pole  22   b , but as generated by the magnetic field generator  30  shows that there has been a change. Thus as shown in FIG. 2 the local magnetic field as generated by the magnetic field generator, in the region of magnetic pole  22   b  is a south pole. 
     Consideration of FIG. 3 shows that the magnetic field, as generated by the magnetic field generator, in the region of magnetic pole  22   b  is now a north pole. Thus, it is the change in magnetic field as generated by the magnetic field generator that causes the lock link  22  to move. Furthermore, for a change in magnetic field to have an effect on lock link  22 , that change in magnetic field must, necessarily, be local to the lock link  22 . 
     FIG. 4 shows the door latch mechanism  10  in a locked condition with the child safety feature off. It should be noted that the magnetic field generator  30  has been rotated in an anticlockwise direction when compared with FIG.  1 . This results in north magnetic pole  22   b  being attracted towards the magnetic field generator and ensuring that operation of outside release lever  40  does not release the latch mechanism. Furthermore, the rotation of the magnetic field generator  30  has caused north magnetic pole  21   b  to be repelled from the magnetic field generator causing inside lock link  21  to rotate anticlockwise about axis  21   a . Thus abutment  21   c  of inside lock link  21  is contacted by abutment  45  of inside release lever  43  when it is operated. This causes anticlockwise rotation of the pawl lifter  20  about axis  16  resulting in unlatching of the door mechanism and allowing the door to be subsequently opened. Stop  21   d  limits the anticlockwise rotation of inside lock link  21 . It should be noted that the operation of the inside release lever  43  also causes abutment  46  to contact lever  35  causing rotation of magnetic field generator  30  to the position shown in FIG.  5 . This prevents a vehicle occupant inadvertedly locking himself out of the vehicle since opening of the door from the inside automatically unlocks the door, allowing subsequent opening from the outside. 
     FIG. 5 shows the door latch mechanism  10  in an unlocked position with the child safety feature off. It can be seen that the magnetic field generator has been rotated (either by operating the inside release lever when the magnetic field generator was in the position shown in FIG. 4 or by independent rotation of the magnetic field generator directly e.g. by a power actuator) such that north magnetic pole  22   b  is repelled away from the magnetic field generator  30  allowing operation of the outside release lever  40  to unlatch the latch mechanism as described above. Furthermore north magnetic pole  21   b  is repelled away from the magnetic field generator  30  thus ensuring that operation of the inside release lever also unlatches the door mechanism. 
     FIG. 6 shows the door latch mechanism  10  in a released position. This is achieved by rotation of magnetic field generator  30  in a anticlockwise direction which allows contact between corresponding lost motion abutments (not shown) on the pawl lifter  20  and magnetic field generator  30 . Such lost motion abutments allow the magnetic field generator  30  to rotate the pawl lifter  20  to release the door latch mechanism independently of the operation of the outside release lever  40  or the inside release lever  43 . 
     In this case the combination of the magnetic field generator  30  and inside lock link provides for an actuator according to the present invention. Furthermore the combination of the magnetic field generator  30  and the outside lock link provide for a further actuator according to the present invention. Thus in this particular case two actuators according to the present invention are provided having a common magnetic field generator. 
     It should also be noted that with the door in an unlocked condition there is a transmission path between the inside door handle and the pawl  15 . This transmission path includes amongst, other release lever  43  and inside lock link  21 . A further transmission path is provided between the outside door handle and the pawl  15  which includes, amongst others, the outside release lever  40  and the outside lock link  22 . 
     Note that with the latch mechanism in a superlocked condition the inside lock lever breaks the transmission path between the inside door handle and the pawl  15  and the outside lock lever  22  breaks the transmission path between the outside door handle and the pawl  15 . 
     However, with the latch mechanism in the unlocked condition the inside lock lever forms part of the transmission path between the inside door handle and the pawl and the outside lock link forms part of the transmission path between the outside door handle and the pawl. 
     In this case locking of the latch mechanism is of the free wheeling type i.e. with the door in a locked condition operation of an outside door handle is possible but does not open the latch. 
     In further embodiments of the present invention an actuator according to the present invention may be provided which provides for block type locking i.e. the output element of the actuator prevents movement of say an outside door handle. 
     In further embodiments the inside and outside lock links can be mounted directly on the pawl. 
     In the embodiments shown the magnetic field generator comprises an array of north and south magnetic poles and the output elements also include a magnetic pole (in this case a north magnetic pole). In further embodiments the array of magnetic poles on the magnetic field generator can be varied as can the polarity of the magnetic poles on the output element. 
     In a further embodiment the output elements need not include any magnetic poles but could consist of a material that is attracted to both a north and south magnetic pole of the magnetic field generator under these circumstances it would be possible to arrange for a resilient means to bias the output elements away from the magnetic field generator when a neutral magnetic field is generated in the vicinity of the output elements and when a magnetic field, either north or south is generated in the vicinity of the output element then that output element would be attracted towards the magnetic field generator. 
     In further embodiments the magnetic field generator could be in the form of one or more electro-magnetics. Furthermore one or more output elements could include an electromagnet arrangement. 
     In a yet further embodiment it is not necessary to move the magnetic field generator since it is possible to shield the output elements from the magnetic field generated by the magnetic field generator. To this end a magnetic shield could be moved between the output element and the magnetic field generator to effect a change in the magnetic field local to the output element. 
     Consideration of FIG. 7 shows, schematically, an actuator  108  having an electro magnetic  160 , a moveable shield  162 , and an output element  164  which is bias to the position as shown in FIG. 7 by spring  166 . 
     With the magnetic shield  162  in the position as shown in FIG. 7, the output element  164  is bias to the position as shown in FIG. 7 by spring  166 . 
     However, when the magnetic shield  162  is moved to the lower chain dotted position A, then the output element  164  is no longer shielded from the effects of the magnetic field as generated by the electro magnet  160 , and moves to the position shown chain dotted at B. 
     The aforementioned description is exemplary rather that limiting. 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, one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. Hence, within the scope of the appended claims, the invention may be practiced otherwise than as specifically described. For this reason the following claims should be studied to determine the true scope and content of this invention.