Abstract:
An actuator for a latch is provided, the actuator having: a motor operatively coupled to a gear train; and a rack moveably mounted to the actuator for linear movement with respect to a housing of the actuator, wherein the gear train comprises: a worm; a worm gear and a pinion gear, wherein the pinion gear is rotatably mounted to the worm gear and the pinion gear has a plurality of teeth configured to engage a portion of the rack, wherein the axis of rotation of the worm is perpendicular to the axis of rotation of the worm gear and the pinion gear.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/940,423 filed on Feb. 15, 2014, the entire contents of which are incorporated herein by reference thereto. 
         [0002]    This application also claims the benefit of U.S. Provisional Patent Application Ser. No. 61/942,833 filed Feb. 21, 2014, the entire contents of which are incorporated herein by reference thereto. 
     
    
     BACKGROUND 
       [0003]    Various embodiments of the present invention relate to a latch and more particularly, an actuator for a vehicle latch. 
         [0004]    In some applications, latches are required to perform numerous operations within limited confines of an application area of the item they are installed in. 
         [0005]    Accordingly, it is desirable to provide a latch with an actuator that is able to perform the required functions while being subject to certain space requirements. 
       SUMMARY OF THE INVENTION 
       [0006]    An actuator for a latch is provided. The actuator having: a motor operatively coupled to a gear train; and a rack moveably mounted to the actuator for linear movement with respect to a housing of the actuator, wherein the gear train comprises: a worm; a worm gear and a pinion gear, wherein the pinion gear is rotatably mounted to the worm gear and the pinion gear has a plurality of teeth configured to engage a portion of the rack, wherein the axis of rotation of the worm is perpendicular to the axis of rotation of the worm gear and the pinion gear. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    These and/or other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: 
           [0008]      FIG. 1  is an exploded view of an actuator according to an embodiment of the present invention; 
           [0009]      FIG. 2  is line drawing of the view of  FIG. 1 ; 
           [0010]      FIG. 3  is a view of the actuator in a locked state; 
           [0011]      FIG. 4  is line drawing of the view of  FIG. 3 ; 
           [0012]      FIG. 5  is a view of the actuator in a unlocked state; 
           [0013]      FIG. 6  is line drawing of the view of  FIG. 5 . 
       
    
    
       [0014]    Although the drawings represent varied embodiments and features of the present invention, the drawings are not necessarily to scale and certain features may be exaggerated in order to illustrate and explain exemplary embodiments the present invention. The exemplification set forth herein illustrates several aspects of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
       DETAILED DESCRIPTION 
       [0015]    Reference is made to the following U.S. Pat. Nos. 3,969,789; 6,568,741; 6,679,531; 8,348,310 and U.S. Patent Publication Nos. US 2010/0127512; US 2011/0204659; US 2012/0292927 and provisional Patent Application Ser. No. 61/806,530 filed Mar. 29, 2013, the entire contents each of which are incorporated herein by reference thereto. 
         [0016]    Referring now to the FIGS. and in particular,  FIGS. 1-6 , an actuator  10  for a latch is illustrated. In one embodiment, the latch is a vehicle door latch or any other type of vehicle latch. Latch has an actuator  10  operatively coupled to components of the latch that are located within a latch housing. In one embodiment, a rack  12  is movably mounted to the actuator  10 . Movement of the rack  12  actuates other component(s) of the latch, for example a detent lever or pawl that operatively engages a claw or fork bolt of the latch and thus movement of the rack can place the latch that is operatively coupled to the actuator in a locked or unlocked state. It is, of course, understood that the rack may also be configured to operatively engage other components of the latch such as a lock lever. It is, of course, understood that the lock lever may also be configured to operatively engage other components of the latch and the interaction of the lock lever to the detent lever is one of many applications and/or operations that may be used alone or in combination with other features/operations of the latch. For example, movement of the lock lever via movement of the rack may couple or uncouple a detent lever or pawl of the latch from a release lever or release handle such that movement of the same may either open the latch or have no effect on the latch. In other words movement of the lock lever via movement of the rack locks or unlocks the latch by coupling or uncoupling components of the latch through movement of the lock lever operably coupled to an end of the rack. Still further and in an alternative embodiment, the rack may comprise or be a portion of the lock lever such that movement of the rack causes the desired latch function. 
         [0017]    In one embodiment, the rack  12  is driven by a motor  14  of the actuator  10  via a gear train  16  operatively coupled to the motor  14  and the rack  12 . As illustrated, the actuator  10  only utilizes three gears that are also three separate components to reduce the velocity and allow the last component (e.g., rack  12 ) in the mechanism to exert the required force. The first component of the gear train  16  which is connected to the motor shaft is a helical gear normally called a worm  18 . The second component is a helical gear normally called a worm gear  20  which is mounted at a ninety degree angle with respect to the first gear or worm&#39;s axis of rotation  22 . The worm gear&#39;s axis of rotation is illustrated as axis  24 . This second gear  20  is in turn connected via a positive and unique surface contact with a component or pinion gear  26  that has a spur gear, which in turn moves the rack  12 , which is the last component and output of the actuator  10 . 
         [0018]    The described crossed axis gear train mechanism has several advantages with respect to other actuators in that the number of required gears is reduced to only three and the number of gear meshes or gear pairs is reduced to two. In addition, the engagement between the second and third gear is not via a gear mesh, which eliminates the accumulation and subsequent amplification of backlash in the system. Also, the fact that the helical gears have crossed axes required the uses of helical gears which create less noise as the transmission of power is carried out through a sliding motion as opposed to the harsh tooth to tooth contact inherent to the spur gears. 
         [0019]    Accordingly, the worm/worm gear configuration creates a more cost efficient and a quieter actuator  10 . 
         [0020]    The actuator  10  has a housing  28  and an associated cover  30  as well as an unlock switch  32  and a door ajar switch  34 . The unlock switch is mounted to an unlock switch carrier  36  while the door ajar switch  34  is mounted to a door ajar switch carrier  38 . 
         [0021]    As mentioned above, worm gear  20  is operatively coupled to a worm  18  which is rotatably driven by motor  14 . Gear  26  is rotatably mounted to worm gear  20  about axis  24  such that gear  26  can rotate with respect to worm gear  20  about axis  24 . Gear  26  also has a protrusion  40  that is located between a pair of features  42  and  44  of worm gear  20  such that as worm gear  20  rotates in one direction (e.g., clockwise) from a home or central position and the actuator  10  is in the locked position illustrated in  FIGS. 3 and 4 , feature  42  will contact protrusion  40  and thus rotate gear  26  clockwise and accordingly move rack  12  linearly in the direction of arrow  46  between a first position and a second position with respect to the actuator  10  so that the actuator is now in the locked position illustrated in  FIGS. 5 and 6 . 
         [0022]    After this movement, the worm gear  20  returns to the home or central position illustrated in  FIGS. 3 and 4  via counter clockwise movement while gear  26  stays in the position illustrated in  FIGS. 5 and 6 . In other words and when viewing  FIGS. 3-6 , clockwise movement of the worm gear  20  from the central or home position of  FIGS. 3 and 4  will move gear  26  clockwise and rack in the direction of arrow  46 . Afterwards, worm gear  20  is spring biased to rotate counter clockwise back to the home or central position illustrated in  FIGS. 3 and 4  as well as  FIGS. 5 and 6  via a return spring  48  however, gear  26  and rack  12  stay in the position illustrated in  FIGS. 5 and 6 . 
         [0023]    When the actuator is in the position illustrated in  FIGS. 5 and 6 , feature  44  of the worm gear is adjacent to protrusion  40  and thus counter clockwise movement of worm gear  20  will then rotate gear  26  in a counter clockwise manner and accordingly move rack  12  in a direction opposite to arrow  46  and thus move the rack from the unlocked position ( FIGS. 4 and 5 ) to the locked position of ( FIGS. 3 and 4 ). Once in this position, the return spring  48  rotates the worm gear  20  in a clockwise direction back to the home or central position illustrated in  FIGS. 3 and 4  such that feature  42  is now positioned to contact protrusion  40  when worm gear  20  is rotated clockwise. 
         [0024]    It being understood that in one embodiment, the distance between features  42  and  44  is larger than protrusion  40  so that the aforementioned movement of worm gear  20  with respect to gear  26  is possible. 
         [0025]    The return spring  48  is configured to be located between the housing  28  and worm gear  20  in order to provide a biasing force to return the worm gear  20  back to the home or central position after the motor  14  is denergized such that either feature  42  or  44  is positioned to make contact with protrusion  40  depending on the state of the latch or actuator  10  (e.g., locked or unlocked). Accordingly and through the rotational movement of the worm gear  20  in opposite directions linear movement of the rack  12  in the direction of arrows  50  is possible. 
         [0026]    A switch  32  is positioned to be actuated by a surface or cam surface  52  of the rack  12  as is moves in the directions of arrows  50  between the locked and unlocked positions. As such movement of the rack or its current location or state is determined by the state switch  32  is in (e.g., closed or open depending on the location of surface or cam surface  52  of rack  12 ). When activated, the motor  14  will drive the gear system or gear train  16  and move the rack  12  linearly. The rack  12  and/or the actuator  10  and accordingly the associated latch will stay in the locked or unlocked position until the motor  14  is once again activated and the state of the actuator changes (e.g., from locked to unlocked or unlocked to locked). Spring  48  returns the worm gear to a central position or home position so that either one of features  42  or  44  is ready to contact protrusion  40  depending on the state of the actuator (e.g., locked or unlocked). The will occur when the motor  14  is operated in one of two directions and reversing the flow of current to the motor  14  will reverse the direction of the motor  14  and move the rack  12  in an opposite direction thus, changing the state of the actuator  10  from lock to unlock or vice versa. Once the state has been changed the spring  48  will again return the gear train  16  and/or worm gear  20  to a central position so that either feature  42  or  44  is ready to contact protrusion  40 . 
         [0027]    As illustrated and as mentioned above, the cam surface  52  of the rack  12  is integrally formed therewith and the cam surface is configured to actuate switch  32  as the rack  12  is moved linearly. This allows the actuator  10  to have a more cost efficient design as the number of separately required components are reduced as the rack  12  is used as a multi-functional component. 
         [0028]    For example and as discussed above, the rack  12  is a link between a gear of the gear train and an arm or a lever of the latch in order to transmit the force and travel given by the actuator. The system also accommodates for loss of travel in order to avoid to back driving the gearing system when the mechanism is subjected to a manual operation. The cam feature  52  allows the position of the actuator to be detected by activation of a switch, which negates the need for a separate component to sense the position of the actuator. Since the lock/unlock switch  32  is integrated into the actuator  10  the necessity for an exclusive connector for a switch outside of the actuator was eliminated and electrical traces are optimized as there is now a common terminal for several switches. 
         [0029]    Also, a feature  70  is located at an end portion of the rack  12 . The configuration of the feature  70  allows for a bumper to be eliminated from the interface between the rack  12  and a lock/unlock lever  72  (illustrated schematically in  FIGS. 3-6 ). The configuration of feature  70  allows for it to be received in a complimentary opening or feature of the locking lever  72  operatively coupled to the rack  12  and the cooperation of feature  70  and its associated opening or feature of the locking lever  72  reduces the need for a bumper to reduce the noise between these components. Accordingly, a multifunctional rack  12  is provided. 
         [0030]    Switches  32  and  34  are operatively coupled to a controller or microcontroller  54  that is provided with the states of switches  32  and  34  and can thus operate the motor  14  in the aforementioned opposite directions based upon the states or information received from the switches  32  and  34  or at least switch  32 . 
         [0031]    This arrangement or design disclosed herein also allows for a compact design. In addition, this design or arrangement also allows for less movable components required to be located between the motor  14  and the rack  12  thus reducing cost, noise, size requirements, possible wear issues etc. 
         [0032]    Reduction in the number of components and/or gears reduces the sensitivity of the transmission between the components and/or gear as the backlash between each pair of gears is minimized due to the reduced amount of pairs of gears. Also, the time required to lock and unlock the latch by the motor is reduced as the motor does not have to overcome lost motion created by accumulated backlash. Moreover, reduced backlash between each gear reduces the amount of noise created by the actuator. Still further, the gear train system provides desired gear train ratios without numerous gears and gear pairs nor does it require a parallel shaft gear train. 
         [0033]    As used herein, the terms “first,” “second,” and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another, and the terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. In addition, it is noted that the terms “bottom” and “top” are used herein, unless otherwise noted, merely for convenience of description, and are not limited to any one position or spatial orientation. 
         [0034]    The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., includes the degree of error associated with measurement of the particular quantity). 
         [0035]    While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.