Patent Publication Number: US-9835236-B2

Title: Linear actuator assembly

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is the National Stage of International Patent Application No. PCT/IB2012/002431, filed on Nov. 21, 2012, which claims the benefit of U.S. Provisional Patent Application Ser. No. 61/562,149 filed Nov. 21, 2011, the contents of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to a linear actuator assembly, and more specifically to a linear actuator assembly for use in shift by wire transmission systems. 
     2. Description of the Related Art 
     A technology that is becoming increasingly common in gearboxes in vehicles is so-called “shift by wire” technology. In other words a system where there is no mechanical connection between the gear lever and the gearbox. Instead, such systems have an electronic connection between a gear selector, arranged in association with the gear lever, and the gearbox. The position of the gear lever in the gear selector is read off by a sensor arrangement that sends information about the position of the gear lever to the gearbox, whereupon a required gear position is assumed. 
     Linear electromechanical actuators, also known as linear actuator assemblies, are useful in vehicle transmissions to facilitate gear selection and provide shift-by-wire functionality. These linear actuator assemblies offers a number of advantages over electromechanical systems based on electric motors and gearboxes in that their outer appearance is similar to a mechanical cable end and thus allows simple attachment and interface to existing Bowden cable operated transmissions. The present invention provides simple, robust linear actuator assemblies having electronic and mechanical control. 
     SUMMARY OF THE INVENTION AND ADVANTAGES 
     The present invention provides a linear actuator assembly comprising a housing and a motor at least partially supported by the housing. The linear actuator assembly also comprises an outer sleeve coupled to the housing and defining a working chamber with the outer sleeve defining a longitudinal axis and an inner sleeve disposed within the working chamber and movable between a retracted position and an extended position along the longitudinal axis relative to the outer sleeve. The inner sleeve has a first end and an opposing second end and a series of threads disposed along at least a portion of the sleeve. A screw is coupled to the motor and extends outwardly from the motor along the longitudinal axis with the screw having a threaded exterior surface engaging the threads of the inner sleeve, wherein the rotation of the motor rotates the screw through the threads of the inner sleeve and facilitates the movement of the inner sleeve between the retracted and extended positions along the longitudinal axis. The linear actuator assembly also comprises a stop mechanism limiting the movement of the inner sleeve relative to the outer sleeve in the extended position, the stop mechanism having a first portion associated with the outer sleeve and a second portion associated with the inner sleeve with the first and second portions abutting each other when the inner sleeve is in the extended position to define a hard stop. 
     The linear actuator assembly may be utilized in transmission shift by wire assemblies of vehicles. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a linear actuator assembly in accordance with one embodiment of the present invention. 
         FIG. 2A  is an exploded perspective view of the linear actuator assembly of  FIG. 1 . 
         FIG. 2B  is a rear perspective view a portion of a housing and an outer sleeve of the linear actuator assembly of  FIG. 2A . 
         FIG. 2C  is a front perspective view of  FIG. 2B . 
         FIG. 2D  is another rear perspective view of the portion of the housing and outer sleeve with an inner sleeve and screw disposed within the outer sleeve of the linear actuator assembly of  FIG. 2A . 
         FIG. 3  is a partially cross-sectioned side view the linear actuator assembly of  FIG. 1 . 
         FIG. 4  is a partially cross-sectioned top view of the linear actuator assembly connected to a gearshift lever in a fully retracted position. 
         FIG. 5  is a partially cross-sectioned top view of the linear actuator assembly connected to a gearshift lever in a fully extended position. 
         FIG. 6  is a partially cross-sectioned side view of a portion of the linear actuator assembly of  FIG. 1 . 
         FIG. 7  is a perspective view of the linear actuator assembly mounted within an alternative bracket assembly in accordance with another embodiment of the present invention. 
         FIG. 8  is a partially cross-sectioned side of a linear actuator assembly connected to a gearshift lever in a fully retracted position in accordance with yet another embodiment of the present invention. 
         FIG. 9  is a partially cross-sectioned side of a linear actuator assembly connected to a gearshift lever in a fully extended position in accordance with the embodiment of  FIG. 8 . 
         FIG. 10  is a partially cross-sectioned side of a linear actuator assembly connected to a gearshift lever illustrating the positioning of a gearshift lever coupled to the linear actuator assembly in three positions in accordance with the embodiment of  FIG. 8 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the  FIGS. 1-6 , wherein like numerals indicate like or corresponding parts throughout several views, a linear actuator assembly  30  in accordance with one exemplary embodiment is generally shown. The linear actuator assembly  30  may be utilized in transmission shift by wire assemblies of vehicles. 
     The linear actuator assembly  30  includes a motor  32  disposed in and at least partially supported by a housing  34 . The housing  34 , in certain embodiments, includes a first portion  35  mated or otherwise fixedly coupled to a second portion  37 . The motor  32  includes an output shaft  36  extending through an aperture  38  in a ring gear  56  that is fixedly coupled to the motor  32 . The assembly  30  may be seated onto, or fixedly attached, to a bracket assembly  31 . 
     The output shaft  36  includes a first end extending into the motor  32  and second end  44  extending outwardly away from the motor  32 . The second end  44  preferably includes a splined outer surface  46 . The motor  32  and output shaft  36  are shown schematically in  FIG. 3-5 . 
     The assembly  30  also includes a gear assembly  50  including a plurality of planetary gears  52  located radially around and engaged with a central, or sun gear  54 . The planetary gears  52  are located radially within the ring gear  56  that is fixed within the space between the housing  34  and the motor  32 . The sun gear  54  preferably includes an internal aperture that mates to the outer surface  46  of the output shaft  36  when the output shaft  36  is coupled to the sun gear  54 . in certain embodiments, the output shaft  36  is press fit within the aperture of the sun gear  54 . When powered, the output shaft  34  of the motor  32  will rotate the sun gear  54 , which in turn rotates the plurality of planetary gears  52  in response. As the planetary gears rotate  52 , they travel in a circular manner along the geared inner surface of the fixed ring gear  56  and about a center axis  62 . As best shown in  FIG. 2A , each of the planetary gears  52  is rotatably mounted to a planet carrier  64  using a pin or other fastening device. The planet carrier  64  includes an aperture  74 . 
     The linear actuator assembly  30  has an outer sleeve  90  defining a first end  92  and a second end  94 . The outer sleeve  90  also defines a longitudinal axis and an interior surface  96  defining a working chamber and an exterior surface  97 . As best shown in  FIG. 2B , the interior surface  96  also includes a series of inwardly projecting flanges  93 , wherein a respective pair of the series of flanges  93  defines a respective guide slot  95 . The longitudinal axis may be parallel to or equivalent to the center axis  62 . The working chamber extends from the first end  92  to the second end  94 . A cap or seal-like structure  98  having a shoulder  99  is mounted to the second end  94  of the outer sleeve  90 . In the illustrated embodiment, the outer sleeve  90  is a portion of the housing  34  (i.e., is integrally formed with the housing  34 ). In particular, the outer sleeve  90  abuts the second portion  37  of the housing  34  to define a stepped portion  41 . Alternatively, the sleeve  90  may be separately affixed or otherwise coupled to and extend from the housing  34 . 
     The linear actuator assembly  30  also has an inner sleeve  100 . As best shown in  FIGS. 2D and 3-5 , the inner sleeve  100  is disposed within the working chamber of the outer sleeve  90 . The inner sleeve  100  has a first end  102  and a second end  104 . The inner sleeve  100  also defines the longitudinal axis and an interior surface  106  defining an inner region  108 . Referring specifically to  FIGS. 2C, 2D and 4-5 , the inner sleeve  100  further includes an exterior surface  110  having a plurality of tabs  111 , with each of the plurality of tabs  111  disposed within a respective one of the plurality of guide slots  95  of the outer sleeve  90 , as best shown in  FIG. 2D . Also, each of the tabs  111  define a respective shoulder  112  near the first end  102 . In addition, the inner sleeve  100  is cylindrical near the second end  104 , but becomes semi-cylindrical nearer to the first end  102 , and therefore defines a cylindrical region  103  and a semi-cylindrical region  105 . A slot  109  is formed in the interior surface  106  of the semi-cylindrical region  105  of the inner sleeve  100 . Further, the tabs  111  extend beyond the semi-cylindrical region  105  at the first end  102  of the inner sleeve  100  towards the motor  32 . As best shown in  FIG. 6 , the portions of the tabs  111  that extend beyond the semi-cylindrical region  105  of the first end  102  define a gap  114  in the inner sleeve  100  wherein a portion of the screw  102  remains exposed. 
     A protective shield  107  is mounted to or otherwise coupled to the second end  104  of the inner sleeve  100  and extends from the second end  104  over the exterior surface  97  of the outer sleeve  90 . The shield  107  can be integrally formed with the inner sleeve  100  or, as shown, may be formed as a separate piece and coupled to the inner sleeve  100  at the second end  104 . The shield  107  preferably surrounds the inner sleeve  100  such that the inner sleeve  100  is not exposed during movement and such that the shield  107  overlies at least a portion of the outer sleeve  90  during movement between a fully extended position, as shown in  FIG. 5 , and a fully retracted position, as shown in  FIG. 4 . An o-ring (not shown) mounted on a groove within the inner surface of the shield  107  and abutting the outer sleeve  90  may be utilized to seal the shield  107  to the outer sleeve  90 . 
     The linear actuator assembly  30  further includes a screw  120 . The screw  120  is disposed in the inner region  108  of the inner sleeve  100 . The screw  120  has a first end  122  and a second end  124 . The screw  120  also has a threaded exterior surface  126  along a portion of its length. An adaptor  130  coupled within the housing  34  is fixedly coupled to the first end  122  of the screw  120 . The outer surface  134  of the adaptor  130  is preferably press fit or otherwise contained within the aperture  74  of the planet carrier  64 . As such, the screw  120  is coupled to the motor  32  through the gear assembly  50  (i.e., the gear assembly  50  is disposed between the motor  32  and the screw  120 ) and extends outwardly from the motor  32  along the longitudinal axis. The assembly  30  also includes a bearing  80  coupled within the housing  34  with the adaptor  130  being supported by the bearing  80  to facilitate rotation of the adaptor  130 , fix the screw  120  longitudinally, and absorb axial forces to protect the motor  32 . 
     The inner sleeve  100  includes a nut  140  having a threaded interior surface  142  defining a series of threads which are threadingly engaged with the threaded exterior surface  126  of the screw  120  and is affixed within the slot  109  of the interior surface  106  of the inner sleeve  100 . Thus, the nut  140  remains in a fixed location relative to the inner sleeve  100  as the screw  120  is rotated such that the nut  140  and the inner sleeve  100  move as a unit. In alternative embodiments, a nut  140  is not utilized, and thus the threaded exterior surface  126  of the screw  120  is threadingly engaged with the threaded interior surface  142  of the inner sleeve  140  along the portion of the length illustrated as including the nut in  FIGS. 1-7 . 
     When powered, the output shaft  36  of the motor  32  will rotate the sun gear  54 , which in turn rotates the plurality of planetary gears  52  and planet carrier  64  around the center axis  62 . The rotation of the planet carrier  64  in turn rotates the adaptor  130 , which in turn rotates the screw  120 , which will rotate within the threaded interior surface  142  of the nut  140 . The nut  140  and inner sleeve  100  will move axially as a unit along the length of the screw  120  and outer sleeve  90 , with the respective plurality of tabs  111  moving axially within each of the respective plurality of guide slots  95  of the outer sleeve  90  and along the longitudinal axis in response to the rotation of the screw  120 . Notably, the coupling of the plurality of tabs  111  within the respective plurality of guide slots  95  prevents the inner sleeve  100  from rotating as a unit with the screw  120 . The screw  120  remains longitudinally fixed relative to the outer sleeve  90  and the longitudinal axis while rotating. In addition, the outer sleeve  90  remains fixed to the housing  34  and fixed relative to the housing  34  during movement of the inner sleeve  100 . 
     The inner sleeve  100  can be linearly displaced axially along the longitudinal axis relative to the screw  120  and outer sleeve  90  in a first longitudinal direction when the motor  32  is rotating in a first direction (i.e., the first rotational direction) until such time as the shoulder  112  of the tab  111  on the inner sleeve  100  is brought into contact with the shoulder  99  of the cap  98  on the outer sleeve  90 . Stated differently, the linear actuator assembly includes a stop mechanism that limits the movement of the inner sleeve  100  relative to the outer sleeve  90  at the fully extended position, as shown in  FIG. 5 , when a first portion associated with the outer sleeve  90  and a second portion associated with the inner sleeve  100  abut each other to define a hard stop. As the inner sleeve  100  is displaced, the shield  107  is also linearly displaced axially in a direction away from the stepped portion  41  of the housing  34 . Rotating the output shaft  36  and the motor  32  in the opposite direction (i.e., the second rotational direction) will allow the inner sleeve  100  to move axially in the opposite linear direction along the longitudinal axis (i.e. a second longitudinal direction) toward the stepped portion  41  of the housing  34 . This movement will continue until the tabs  111  contact the adaptor  30 , or wherein the protective shield  107  contacts the stepped portion  41  of the housing  34 , or both, as described in greater detail below in the fully retracted position, as shown in  FIG. 4 . Thus, the length of displacement of the inner sleeve  100  relative to the outer sleeve  90  and screw  120  is limited. 
     The linear actuator assembly  30  also includes a shaft  170  with the shaft  170  having an axis. The shaft  170  also has an exterior surface  172  and a first end  174 . The linear actuator assembly  30  also has a gear  176  supported within the housing  34  with the gear  176  having an exterior surface  178 . The shaft  170  is disposed in and abuts the gear  176 . Alternatively, the shaft  170  and gear  176  may be integrally formed as a single piece or mounted together for concurrent rotation. The exterior surface  178  of the gear  176  has teeth. The gear  176  also has an emitter, shown in  FIGS. 1-6  as a magnet  180 , which is attached to and abuts the first or distal end  174  of the shaft  170 . The magnet  180  is located in close proximity to a sensor, shown in  FIG. 2  as a Hall Effect sensor  184 . The magnet  180  has a North Pole  182  and a South Pole  183  that emits a magnetic field. In alternative arrangements, the magnet  180  may be attached to any other portion of the gear  176  or shaft  170 . Further, it can be appreciated that other sensor arrangements could be implemented. A printed circuit board  185  electrically coupled to the Hall Effect sensor  184  is disposed within the housing  34 . The printed circuit board  185  is electrically coupled to a controller  101 . 
     The teeth of the gear  176  are disposed in are threadingly engaged with the threaded exterior surface  126  of the screw  120  such that the gear  176  rotates the shaft  170  and the magnet  180  during the movement of the inner sleeve  100 . As the magnet  180  rotates, the circular movement of the North Pole  182  and the South Pole  183  create a change in the magnetic field. The Hall Effect sensor  184  that is positioned adjacent the magnet  180  detects the change in the magnetic field. The different magnetic field measurements detected by the Hall Effect sensor  184  are electronically transmitted to the printed circuit board  185  and the controller  101  to determine the axial position of the inner sleeve  100  relative to the outer sleeve  90  along the longitudinal axis. The gear  176  should have a gear ratio with the screw  120  that would rotate the magnet  180  approximately 300 degrees for the entire linear displacement of the inner sleeve  100 . The large amount of rotation will provide good variation in the magnetic field between the different positions of the inner sleeve  100  that allows for an accurate determination of the linear positioning of the inner sleeve  100  relative to the outer sleeve  90  in the assembly  30 . 
     As mentioned above, the gear  176  also includes a notch, or cut-out region  177 , that removes approximately 60-120 degrees of the teeth of the gear  176  and therefore defines a first end  179  and a second end  181  of the teeth of the gear  176 . In the fully retracted position, as shown in  FIG. 4 , the first end  102  of the inner sleeve  100  is positioned within the notch  177  of the gear  176  and the second end  181  of the gear  176  is in contact with the threaded portion of the exterior surface  126  of the screw  120 . The gap  114  formed in the inner sleeve  100  provides the necessary clearance for the second end  181  of the gear  176  to remain in contact with the screw  120 . In this position, the inner sleeve  100  is prevented from retracting further towards the motor  32  due the contact of the tabs  111  with the adaptor  30  or wherein the protective shield  107  contracts the stepped portion  41  of the housing  34 . In the fully extended position, as shown in  FIG. 5 , the gear  176  has rotated clockwise approximately 250-300 degrees relative to the positioning of the gear  176  when in the fully retracted position. Stated differently, the complete rotation of the gear  175  from the fully retracted position, as shown in  FIG. 4 , to the fully extended position, as shown in  FIG. 5 , is approximately 250-300 degrees. 
     In certain embodiments, as noted above, the linear actuator assembly  30  is utilized in transmission shift by wire assemblies of vehicles. In these embodiments, as shown best in  FIGS. 3-5 , a first terminal  186 , having a terminal end fitting  188 , is coupled to a gear shift lever  224 . The terminal end fitting  188  extends into the inner region  108  of the inner sleeve  100  and is connected or otherwise mounted to the inner sleeve  100 . 
     The first terminal  186  includes an interior region  200  that is designed to be mounted about a pin  220  of the gear shifter  224 . The configuration of the interior region  200  of the first terminal  186  and the gear shifter  224  can be of any suitable design. Once mounted, the pin  220  may articulate within the interior region  200  to shift the transmission of a vehicle as desired. The first terminal  186  moves as a unit with the inner sleeve  100  from a first position, corresponding to the fully retracted position of the linear actuator assembly  30 , to a second position corresponding to the fully extended position of the linear actuator assembly  30 . The gear shifter  224  is displaced as the inner sleeve  100  of the linear actuator assembly  30  moves from the fully retracted position to the fully extended position, as best shown in  FIGS. 4 and 5 . 
     Also shown in  FIGS. 1-6  is a second terminal  235  which is coupled to first portion  35  of the housing  34  near the motor  32 . The second terminal  235  is structurally similar to the first terminal  186 , and may accommodate a pin  240  within an interior region  245  similar to the first terminal  186 . However, as opposed to the first terminal  186 , the second damper assembly  235  is not displaced axially relative to the housing  34  and motor  32  as the linear actuator assembly  30  is moved from a fully retracted position to a fully extended position. Stated differently, the second terminal  235 , as one of ordinary skill readily recognizes, is a fixed terminal in a transmission shift by wire assembly, whereas the first terminal  186  is considered the displaceable terminal. However, during gear shifting, the linear actuator assembly  30  may articulate on the pin  240  to facilitate the up or down displacement of the gear shifter  224  during the gear shifter&#39;s pivotal movement. 
     Referring to  FIG. 7 , an alternative mounting bracket assembly  310  to the bracket assembly  31  for attachment to the linear actuator assembly  30  is generally shown. The mounting bracket assembly  310  includes a mount  312 . The mount  312  includes a plate  314  having a first arm  316  and a second arm  318 . In the embodiment shown, the first arm  316  and second arm  318  are generally L-shaped and have an interior surface. The interior surfaces are perpendicular to the plate  314  and parallel to each other. 
     The mounting bracket assembly  310  also includes an actuator bracket  326  rotationally mounted to the first arm  316  and the second arm  318  about a first pivot axis with the first pivot axis being transverse to the longitudinal axis. The housing  34  is supported by the actuator bracket  326  to permit the housing  34  to rotate about the first pivot axis, relative to the plate  314 , as shown by arrow  322 , to assist with installation of the linear actuator assembly  30  on the first terminal  186  and on the gear shifter  224 . 
     The actuator bracket  326  has a bearing  346  defining a second pivot axis transverse to the longitudinal axis and the first pivot axis. The housing  34  has a journal  348 ,  350  rotatably mounted about the bearing  346  to permit the housing  34  to rotate about the second pivot axis. Rotation about the second pivot axis will typically occur during operation of the linear actuator assembly  30 . 
     The bearing  346  of the actuator bracket  326  includes a first end  330  and a second end  332 . The first end  330  includes a curved surface  334  and the second end  332  includes another curved surface  336 . The first end  330  and second end  332  also include angled surfaces  338 ,  340 ,  342 ,  344 . 
     The journal  348 ,  350  of the housing  34  is further defined as two curved ribs  348 ,  350 . The linear actuator assembly  30  can rotate about the second pivot axis of the bearing  346  by the curved ribs  348 ,  350  along the curved surfaces  334 ,  336 , as shown by arrow  320 . The rotation about the second pivot axis is limited when the curved ribs  348 ,  350  of the journal  348 ,  350  abut the angled surfaces  338 ,  340 ,  342 ,  344  of the bearing  346 . As mentioned above, rotation of the linear actuator assembly  30  is necessary to accommodate the arcuate motion of the gear shifter  224  (see  FIG. 4 ). 
     Referring to the  FIGS. 8-10 , wherein like numerals indicate like or corresponding parts throughout several views, a linear actuator assembly  400  in accordance with another exemplary embodiment is shown. Similar to the linear actuator assembly  30 , the linear actuator assembly  400  may be utilized in transmission shift by wire assemblies of vehicles. 
     The linear actuator assembly  400  includes a motor  412  coupled within a housing  413 . The motor  412  includes an output shaft  414 . 
     The output shaft  414  includes a first end  416  and second end  418 . The motor  412  is disposed around and abuts the first end  416  of the output shaft  414 . The second end  418  is disposed in and abuts a bearing  420 . The bearing  420  protects the motor  412  from axial forces. The motor also abuts a case  422 . The case  422  is disposed around the bearing  420  and includes a printed circuit board  424  and Hall Effect sensor  426 . The printed circuit board  424  is electrically coupled to a controller  101 , which typically includes a central processing unit. 
     The linear actuator assembly  400  has an outer sleeve  428  defining a first end  430  and a second end  432 . The first end  430  is disposed in the case  422  and abuts the bearing  420 . The outer sleeve  428  also has an axis and an interior surface  434  defining a working chamber. The working chamber extends from the first end  430  to the second end  432 . The outer sleeve  428  further includes an aperture  436  and a pin  438  with the pin  438  disposed in the aperture  436  and positioned near the second end  432 . The outer sleeve  428  further defines a second aperture  437 , or removed section, located at the second end  432 . 
     The linear actuator assembly  400  also has an inner sleeve  440 . The inner sleeve  440  is disposed within the working chamber of the outer sleeve  428 . The inner sleeve  440  has a first end  442  and a second end  444 . The inner sleeve  440  also has an axis and an interior surface  446  defining a second chamber. The second chamber extends from the first end  442  to the second end  444 . The interior surface  446  of the second chamber includes inwardly projecting collar  443  having a threaded surface  445  defining a series of threads. The collar  443  projects inwardly into the second chamber and is preferably near the first end  442 . The collar  443  may be integrally formed with the inner sleeve  440 , as shown, or separately coupled to the inner sleeve  440 . Referring specifically to  FIG. 8 , the inner sleeve  440  further includes an exterior surface  448  and a slot  450  that extends along a majority of the length of the inner sleeve  440 . 
     The linear actuator assembly  400  further includes a screw  452 . The screw  452  is disposed in the second chamber of the inner sleeve  440 . The screw  452  has a first end  454  and a second end  456 . The screw  452  also has an exterior surface  458 . The exterior surface  458  of the screw  452  is threaded. The first end  454  of the screw  452  abuts the bearing  420 . 
     The inner sleeve  440  is disposed in the working chamber of the outer sleeve  428 . The screw  452  is disposed in the second chamber of the inner sleeve  440 . The threads on the threaded exterior surface  458  of the screw  452  are disposed in and abut the threaded portion  445  of the collar  443  of the inner sleeve  440 . Stated differently, the threads of the exterior surface  458  of the screw  452  are threadingly engaged with the threads of threaded surface  445  of the inner sleeve  440 . The screw  452  is attached to and abuts the bearing  420 . The bearing  420  is disposed around and attached to the second end  418  of the output shaft  414 . 
     When powered, the output shaft  414  of the motor  412  will rotate the bearing  420  and screw  452 . The threads of the threaded exterior surface  458  of the screw  452  will rotate within the threaded surface  445  of the inwardly projecting collar  443  of the inner sleeve  440 . The inner sleeve  440  will move axially along the screw  452 . Referring specifically to  FIG. 7 , in order to prevent the inner sleeve  440  from rotating and extending past the screw  452 , the slot  450  of the inner sleeve  440  is aligned with the aperture  436  of the outer sleeve  428 . The pin  438  is inserted into the aperture  436  and the slot  450 . The pin  438  will remain stationary as the slot  450  of the inner sleeve  440  moves. The inner sleeve  440  can only be displaced the length of the slot  450  as the pin  438  will stop the inner sleeve  440  at each end  451 ,  453  of the slot  450 . Stated differently, the pin  438  and slot  450  define a stop mechanism that limits the range of movement of the inner sleeve  440  axially along a longitudinal axis relative to the outer sleeve  428  between a fully extended position, as shown in  FIG. 8 , and a fully retracted position as shown in  FIGS. 7 and 9 . 
     The linear actuator assembly  400  includes a shaft  460  with the shaft  460  having an axis. The shaft  460  also has an exterior surface  462  and a bottom end  464 . The linear actuator assembly  400  also has a gear  466  with the gear  466  having an exterior surface  468 . The shaft  460  is disposed in and abuts the gear  466 . The gear  466  is disposed within and at least partially supported by the housing  413  and engages the screw  452  through the second aperture  437  in the outer sleeve  428 . The exterior surface  468  of the gear  466  has teeth. The shaft  460  also has a magnet  470  which is attached to and abuts the bottom end  464  of the shaft  460 . The magnet  470  has a north pole  472  and a south pole  474 . 
     The teeth of the gear  466  are disposed in and threadingly engaged with the threaded exterior surface  458  of the screw  452 . The gear  466  will rotate when the screw  452  rotates to change the linear position of the inner sleeve  440 . The gear  466  rotates the shaft  460  and the magnet  470 . As discussed above, as the magnet  470  rotates, the circular movement of the North Pole  472  and the South Pole  474  create a change in the magnetic field. The Hall Effect sensor  426  positioned below the magnet  470  will detect the change in the magnetic field. The different magnetic field measurements detected by the Hall Effect sensor  426  are electronically transmitted to the printed circuit board (not shown), which includes a central processing unit that can determine the linear position of the inner sleeve  440  relative to the outer sleeve  428 . Alternatively, the Hall Effect sensor  426  may itself have the capability for determining the linear position of the inner sleeve  440  relative to the outer sleeve  428  in the assembly  400 . The gear  466  preferably has a gear ratio with the screw  452  that would rotate the magnet  470  approximately 300 degrees for the entire linear displacement of the inner sleeve  440 . The large amount of rotation will provide good variation in the magnetic field between the different positions of the inner sleeve  440 . 
     Similar to the linear actuator assembly  30 , a first terminal  186  may be mounted to the linear actuator assembly  400 . More specifically, a terminal end fitting  188  of the first terminal  186  is disposed within an inner region  475  of the inner sleeve  440 . 
     Similar to the first embodiment shown in  FIGS. 1-6 , the first terminal  186  may be designed to be mounted about a pin  220  of a gear shifter lever  224  and operate in a similar manner. 
     The present inventions have been described herein in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present inventions are possible in light of the above teachings. The inventions may be practiced otherwise than as specifically described within the scope of the appended claims.