Abstract:
A stick shift handle assembly has a stick shift handle and an actuator for releasing the stick shift handle for movement between a plurality of gear positions. The actuator has a housing. A sleeve is disposed between the actuator and the housing. The sleeve and the housing are made of different materials.

Description:
FIELD OF THE INVENTION 
     This invention relates to an actuator for a stick shift handle assembly. 
     BACKGROUND OF THE INVENTION 
     A stick shift handle for an automatic transmission permits a driver to change the gears of a vehicle transmission by moving the stick shift handle between various positions. Typically, the stick shift handle is locked in a particular gear position until unlocked by the driver. The driver unlocks the stick shift handle by pressing a release button either at the front of the stick shift handle or on its side, which, in turn, causes an actuator in the stick shift handle to release the stick shift handle from a shift lock mechanism. 
     Problems may arise with the actuator that unlocks the stick shift handle. Specifically, the stick shift handle, which houses the actuator, is generally made from plastic and fiberglass. This material has a high coefficient of friction and causes the actuator to experience a fair amount of friction when moved. While manufacturers have sought to overcome this problem by placing lubricant between the actuator and the stick shift handle, during frequent use, the lubricant tends to migrate from the area of contact between the actuator and the stick shift handle. 
     In addition, for a side actuating stick shift handle, manufacturers have sought to reduce the effort of unlocking the stick shift handle by employing a cam as an actuator. To unlock the stick shift handle, the driver presses a release button, which causes pivotal movement of the cam. The cam then moves an unlocking member along a linear path. However, the pivoting action of the cam tends to force the unlocking member to move in a pivoting fashion as well. On occasion, this type of movement may cause a backlash through the release button. Manufacturers have sought to eliminate this problem by creating a notch in the cam to prevent the unlocking member from moving radially relatively to the cam. This fix is time consuming to implement. 
     A need therefore exists for a stick shift handle assembly that provides smooth and inexpensive actuation of a shift lock mechanism. 
     SUMMARY OF THE INVENTION 
     The present invention comprises a stick shift handle and an actuator for releasing the stick shift handle for movement between various gear positions. The actuator has a housing that is disposed within the stick shift handle. In contrast to existing stick shift handle assemblies, however, the inventive stick shift handle assembly employs a sleeve between the actuator and its housing. The sleeve has a co-efficient of friction less than the coefficient of friction of the housing or the stick shift handle. In this way, the actuator may slide on the sleeve with less frictional resistance than existing stick shift handle assemblies. 
     The actuator may have a flat surface that contacts a flat surface of the sleeve. Lubricant may be provided between the flat surfaces to facilitate movement of the actuator within its housing. The flat surfaces ensure that the lubricant will not migrate from the area of contact. 
     In addition, the sleeve may have a particular shape to match a shape of the housing. In this way, the sleeve will not move within the housing. The stick shift handle assembly may also employ a motion transmitting member, such as a swizzle stick, to unlock a shift lock mechanism. The actuator may also have a button, which has a sloped surface in contact with another sloped surface of the actuator to allow motion to be transmitted from the button to the actuator in a smooth fashion. 
     For a side-actuating stick shift handle assembly, the inventive stick shift handle assembly employs a stick shift handle that moves between the various gear positions along a first axis. Unlike a front actuation stick shift handle assembly, the side actuation stick shift handle uses an actuator that unlocks the stick shift handle by moving along a second axis transverse to the first axis. The actuator has a first member that moves along this second axis. In addition, a second member moves along a third axis to disengage the shift lock mechanism. The first member has a first sloped surface while the second member has a second sloped surface. The first member transmits motion to the second member through the sloped surfaces. In this way, motion may be transmitted along two different paths with little resistance. 
     The first slope surface may be a rounded surface or an inclined surface. The first member may have a projection that fits into a groove of the housing to prevent rotation of the first member within its housing. In addition, the housing may comprise a first portion extending along the second axis and a second portion extending along the third axis. 
    
    
     
       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  illustrates a stick shift handle assembly of a first embodiment of the invention, showing actuator and sleeve. 
         FIG. 2  illustrates an exploded view of the stick shift handle of  FIG. 1 , highlighting actuator and sleeve. 
         FIG. 3  illustrates the sleeve of  FIGS. 1 and 2  with lubricant. 
         FIG. 4  illustrates the housing of  FIGS. 1 and 2 . 
         FIG. 5  illustrates a second embodiment of the invention, a side actuation stick shift handle assembly. 
         FIG. 6  illustrates the actuator of FIG.  5 . 
         FIG. 7  illustrates a cross-sectional view of the actuator of  FIGS. 5 and 6  in its housing. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  illustrates a cross-sectional view of inventive stick shift handle assembly  10 . Like existing stick shift handle assemblies, inventive stick shift handle assembly  10  has stick shift handle  14 , which allows a driver to shift a vehicle transmission through its various gears. Stick shift handle  14  is prevented from moving from gear shift position to gear shift position by shift lock mechanism  50 , here shown schematically. 
     To release stick shift handle  14  for movement between the various gear shift positions, a driver presses button  60  in the direction of arrow C. Button  60  has first sloped surface  64 , such as a rounded or inclined surface, which also moves in the direction of arrow C to contact second sloped surface  68 , here another rounded or inclined surface, of actuator  18 . Actuator  18  is housed in housing  22 , which may be a separate part or be part of stick shift handle  14 . Actuator  18  then moves in the direction of arrow A and transmits its motion to motion transmitting member  54  to release shift lock mechanism  50 . Following movement of stick shift handle  14  to its proper gear shift position, motion transmitting member  54  and actuator  18  move in the direction of arrow B and return button  60  to its original position along arrow D. 
     In contrast to existing stick shift handle assemblies, inventive stick shift handle assembly  10  employs sleeve  26  between actuator  18  and housing  22 . Sleeve  26  comprises a material having a lower coefficient of friction C 1  than the coefficient of friction of housing  22 , C 2 . Sleeve  26  thus offers a low amount of frictional resistance to actuator  18  within housing  22 . 
     As shown in  FIG. 2 , actuator  18  has first planar area  30  that fits on top of second planar area  34  of sleeve  26 . Accordingly, first planar area  30  slides on second planar area  34 . To further reduce friction between actuator  18  and sleeve  26 , lubricant  37  is placed on sleeve  26  at location  38  to allow actuator  18  to slide on sleeve  26  more smoothly. Because lubricant  37  is placed between first planar area  30  and second planar area  34 , movement of actuator  18  on sleeve  26  causes lubricant to spread evenly over the planar areas  30 ,  34  rather than in one particular area. In this way, sleeve  26  prevents the migration of lubricant away from the area of contact between actuator  18  and sleeve  26 . 
     As shown in  FIG. 3 , sleeve  26  has first cross-section  42  of a particular shape to match, as shown in  FIG. 4 , the shape of second cross-section  46  of housing  22 . Moreover, second cross-section  46  has shoulders  48 . By having shoulders  48 , sleeve  26  is prevented from rotating within housing  22  and is, in fact, locked in place against rotational movement within housing  22 . 
       FIGS. 5-7  illustrate side actuation shift assembly  100 . Inventive stick shift handle assembly  100  has stick shift handle  104 . Stick shift handle  104  moves between gear shift positions along the X axis. As in the previous embodiment, stick shift handle assembly  100  is prevented from moving between gear positions by shift lock mechanism  150 . 
     To release stick shift handle  104  for movement, a driver presses button  102  in the direction of arrow E along the Y axis, as axis transverse to the X axis, to contact actuator  108 . Actuator  108  comprises first member  124 , which extends along the Y axis within first portion  116  of housing  112 , as well as second member  128 , which extends along the Z axis, an axis transverse to both the X and Y axes, within second portion  120  of housing  112 . Movement of button  102  forces movement of first member  124  in the direction of arrow E. 
     As shown in  FIG. 6 , first member  124  has first sloped surface  132 , such as a rounded or inclined surface, while second member  128  has second sloped surface  136 , such as a rounded or inclined surface. Accordingly, movement of first member  124  in the direction of arrow E causes first sloped surface  132  to contact second sloped surface  136 . Motion is transmitted from first member  124  along the direction of arrow E to second member  128  along the direction of arrow A, along the Z axis, through first sloped surface  132  and second sloped surface  136 . Second member  128  moves motion transmitting member  154  to release shift lock mechanism  150  in the direction of arrow A. Once the gear shift position has been changed, motion transmitting member  154  returns along the direction of arrow B to its original position. Motion transmitting member  154  moves second member  128  in this same direction, which ultimately causes first member  124  and button  102  to return to their original positions along the direction of arrow F. This return and release function can be as known in the prior art. Thus, in contrast to other side actuation stick shift handle assemblies, inventive stick shift handle assembly  100  eliminates the cam as well as its pivoting action. In this way, stick shift handle assembly  100  eliminates the backlash associated with other side actuation stick shift handle assemblies. 
     In addition, first member  124  is provided with protrusion  140 , as shown in  FIGS. 6 and 7 . As shown in  FIG. 7 , first portion  116  of housing  112  is provided with groove  144  to receive protrusion  140 . In this way, first member  124  is prevented from rotating within first portion  116  of housing  112 . 
     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.