Abstract:
A sensor assembly is provided with a speed sensor module that is rotatable relative to a bracket between first and second positions. The sensor module need not be translated to accomplish the rotation; therefore, it may remain installed through an aperture of a transmission casing and adjustment between the positions will not involve fluid leakage. The sensor module and the bracket interfit to establish and define both the first and second positions. A method of assembling a sensor module in a transmission includes loosening a bolt holding a bracket to a transmission casing, sliding the bracket relative to the sensor module, and then rotating a sensor module between first and second positions without removing or even translating the module in the casing aperture. Preferably, testing of the sensor module occurs when it is in the first position and the second position is an in-use position.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application 60/1756,152, filed Jan. 4, 2006, which is hereby incorporated by reference in its entirety. 
     
    
     TECHNICAL FIELD  
       [0002]     The invention relates to a sensor assembly for a transmission and a method of assembling a sensor module in a transmission.  
       BACKGROUND OF THE INVENTION  
       [0003]     Transmission output speed sensor modules are typically inserted through the transmission casing so that the sensor end is in the immediate proximity of a non-contact ring with protrusions on its perimeter that are detected by the sensor as they pass by it. The sensor is in contact with transmission fluid within the transmission and an electrical connector end is located outside of the transmission casing, with the electrical connector accessible for connection via wiring to an electronic control module. A dedicated opening through the casing is required for the sensor module. Additionally, a bracket that secures the sensor module portion to the casing is typically bolted to the casing, thus requiring a dedicated bolt opening in the casing. Output speed sensors are tested to ensure functionality within the transmission prior to being shipped to the vehicle assembly plant. A test stand specifically designed to support the transmission during testing is used by the transmission original equipment manufacturer to fully test the transmission and its components (including the output speed sensor). Electrical connectors are positioned on the stand in a location that allows the test stand electrical connectors to interface with the sensor module electrical connector, assuming a standard installed position of the sensor module. If a different installed position of the sensor module is necessary for a different vehicle model, this may be inconsistent with the test stand design. For instance, the test stand electrical connectors may not be able to interface with an electrical connector on the sensor module when the sensor module electrical connector is in a different orientation. Significant capital expenditure would be required to alter the test stand to accommodate more than one electrical connector position or to provide a modified transmission casing in order to reposition the sensor module. Repositioning of either or both the bolt location and the sensor module opening in the casing would require recasting of and retooling for the transmission.  
       SUMMARY OF THE INVENTION  
       [0004]     A sensor assembly is provided with a speed sensor module that is rotatable relative to a bracket between a first position and a second position. The sensor module has a central axis about which it is rotatable. The sensor module need not be translated along the axis to accomplish the rotation; therefore, it may remain installed axially through an aperture of a transmission casing and adjustment between the positions will not involve fluid leakage. The sensor module and the bracket interfit to establish and define both the first and second positions. The sensor module cannot rotate relative to the bracket when interfit with the bracket in the first and second positions. Thus, installation error is minimized. The sensor module is fully operative in both positions. Thus, one position may be optimal for purposes of testing while the other position may be optimal for in-vehicle use with associated packaging issues.  
         [0005]     A method of assembling a sensor module in a transmission includes loosening a bolt holding a bracket to a transmission casing, sliding the bracket relative to the sensor module, and then rotating the sensor module in a casing aperture between first and second positions without removing or even translating the sensor module in the casing aperture. Preferably, testing of the sensor module occurs when it is in the first position. Once tested, the module may be rotated to the second position either prior to or after installation of the transmission on a vehicle chassis. If shipped between testing and installation, the module may be placed in whichever one of the two positions minimizes damage to the module. The second position is the in-use position, and is optimized for packaging with other components.  
         [0006]     The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  is a schematic, fragmentary side-view illustration of a transmission having a sensor assembly installed thereon with a sensor module shown in a first position and in a second position (in phantom) rotated with respect to the first position;  
         [0008]      FIG. 2  is a side-view of the sensor assembly of  FIG. 1 ;  
         [0009]      FIG. 3  is a schematic perspective view of the sensor module used in the sensor assembly of  FIGS. 1 and 2 ; and  
         [0010]      FIG. 4  is a schematic perspective illustration of the sensor assembly of  FIGS. 1 and 2  showing an electrical connector within an electrical connector portion of the sensor module. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0011]     Referring to the drawings, wherein like reference numbers refer to like components,  FIG. 1  schematically shows a transmission  10  having a sensor assembly  12  installed thereon. An aperture  14  extending through a casing  16  of the transmission  10  allows a portion of the sensor assembly  12  to extend within the transmission  10  for sensing rotational speed of an output member (not shown) as is understood by those skilled in the art. The sensor assembly  12  includes a bracket  18  as well as a sensor module  20 . Referring to  FIG. 3 , the sensor module  20  includes a plastic body  19  including a generally cylindrical portion  21  overmolded over a magnetic pickup (not visible within the body  19 ) and including an electrical connector  25  (see  FIG. 4 ) within an electrical connector portion of the body  19 . The body  19  of the sensor module  20  is generally cylindrical so that the sensor module  20  has a central axis  24 . The electrical connector portion is shown in a first position in which the electrical connector portion is referred to as  22 A. The sensor module  20  may be a solid state sensor, a variable reluctance sensor, a magneto-restrictive sensor or a Hall effect sensor, all of which function to create and relay an electrical signal corresponding with the speed of an output member of the transmission. Such sensors are well understood by those skilled in the art. The sensor module  20  must be oriented in the casing  16  with respect to the output member to be able to establish the corresponding signal. The bracket  18  is bolted to the casing  16  with a bolt  23  to secure the sensor module  20  in a desired rotational position. The sensor module body  19  includes the electrical connector portion  22 A that extends radially with respect to the cylindrical portion  21  of the body  19  that extends through the transmission aperture  14 . In  FIG. 1 , the sensor module  20  is shown in the first position in which the electrical connector portion  22 A extends generally downward (i.e., in a six o&#39;clock position with respect to the casing  16 ). The sensor assembly  12  is designed as described herein to allow the sensor module  20  to be rotated about axis  24  to a second position in which the electrical connector portion is designated  22 A in  FIG. 1 . Preferably, the second position is rotated approximately 55 degrees from the first position, although the bracket  18  and sensor module  20  can be designed to allow a rotation of virtually any angle for the second position. The electrical connector portion  22 A is rigidly formed with respect to the cylindrical portion  21  of the body  19  and rotates therewith so that it is accessible at two different locations, the generally vertical location (see  FIG. 1 ) consistent with the first position of electrical connector portion  22 A and a second location consistent with the second position in which the electrical connector portion is designated  22 B.  
         [0012]     Referring now to  FIG. 2 , the sensor assembly  12  is shown with the sensor module  20  orientated in the first position of  FIG. 1 . The first position is established by interfacing the bracket  18  with the sensor module  20 . Specifically, a locking finger or extension  26  formed on the bracket  18  extends within a first recess  28  formed along an outer surface  30  of the sensor module  20 , as may be better viewed in  FIG. 3 . A protrusion or stopper  32  extending radially from a circumferential shoulder  33  of the sensor module  20  rests against a shoulder portion  34  (see  FIG. 2 ) of the finger  26  to further establish the first position. When the bolt  23  of  FIG. 1  is tightened, first and second arms  36 ,  38  of the bracket  18  rest against the shoulder  33  of the sensor module  20  (better viewed in  FIG. 3 ), providing an axial tightening force to secure the relative positioning of the bracket  18  and sensor module  20  to one another and to the casing  16 , and thereby lock the finger  26  within the recess  28  and against the protrusion  32 . The arms  36 ,  38  are between the circumferential shoulder  33  and a second circumferential shoulder  39  to partially surround the sensor module  20 . First and second inwardly-extending detents  40 ,  41  extend from the respective bracket arms  36 ,  38 , to further surround the sensor module  20  and prevent the bracket  18  from moving from around the sensor module  20 , as the detents  40 ,  41  establish a clearance smaller than the outer diameter of the portion of the sensor module body  19  between the shoulders  33 ,  39 . In order to rotate the sensor module  20  to the second position indicated in  FIG. 1 , the bolt  23  is loosened and the bracket  18  is slid radially away from the sensor module  20  (in the direction of arrow A of  FIG. 1 ). A slotted opening  42  of the bracket  18  through which the bolt  23  extends allows the bracket  18  to be slid radially with respect to the sensor module  20  without removing the sensor module  20  from the aperture  14  of  FIG. 1 . In fact, the sensor module  20  is not translated along axis  24  when it is rotated from the first position to the second position. Sliding the bracket  18  removes the finger  26  from the recess  28  and the shoulder portion  34  from contact with the protrusion  32 . Thus, the sensor module  20  may be rotated clockwise in  FIG. 2  until recess  44  is in the same position as recess  28  was in the first position, such that the finger  26  aligns with the second recess  44 . The bracket  18  is then slid radially toward the sensor module  20  (in the direction of Arrow B of  FIG. 1 ) so that the finger  26  extends within the second recess  44 , thus preventing further rotation of the sensor module  20  relative to the bracket  18 . The bolt  23  is then tightened to maintain the relative position of the sensor assembly  12  with respect to the casing  16  and the sensor module  20  with respect to the bracket  18 .  
         [0013]     By providing a sensor assembly  12  that may be rotated from first to second positions without removing or even translating the sensor module  20  along axis  24  with respect to the aperture  14  in the casing  16 , the first and second positions may be advantageously employed with respect to required testing and function of the sensor assembly  12 . For instance, it may be desirable to maintain the sensor module  20  in the first position for testing. An available test stand which must interface with the electrical connector  25  may be designed to align with the electrical connector portion  22 A when it is in the first position. This is likely if the first position is also the in-use position on a vehicle model having the transmission for which the test stand was originally designed. The second position of the electrical connector portion  22 B in  FIG. 1  may be desirable to alleviate other interference issues that may arise with installation on a vehicle, for instance, other vehicle components or electrical wiring may interfere with the first position. Thus, the two relative positions are achieved with a minimum number of process and assembly steps, namely loosening the bracket  18  with respect to the casing  16 , sliding the bracket  18  and rotating the sensor module  20  along axis  24  to the second position. The bracket is first slid away from the sensor module to allow rotation of the module and then slid back toward the sensor module such that the finger  26  interfits with the second recess  44  of the sensor module body portion  19  to establish the second position. Because translation of the sensor module  20  along axis  24  in the aperture  14  is not necessary, transmission fluid leakage is avoided. Additionally, it may be advantageous to ship the transmission  10  from an assembly location to an installation location with the sensor module  20  in the first position. During transport at the assembly location and shipping to the installation location, the center of mass of a typically non-symmetrical transmission may cause a tendency to tip. The narrower profile of the essentially vertical electrical connector portion  22 A of the sensor module  20  in the first position (when viewed from below) minimizes breakage during shipping of the transmission  10 .  
         [0014]     Other embodiments of a sensor assembly may also be employed within the scope of the present invention. For example, a bracket having a transverse slot may be used that interfaces with two pins circumferentially-spaced from one another and formed in the sensor module body. The pins may be spaced such that they fall at opposing ends of the slot, spanning the width of the slot, thus preventing rotation of the sensor module relative to the bracket and establishing a first position. If one of the pins is of a relatively weak material, such as plastic, it may be sheared when an assembler loosens the bolt and applies sufficient rotational force, thus allowing rotation of the sensor module relative to the bracket. The other pin, which is preferably a relatively strong material, such as metal, will act as a stopper when the sensor module is rotated to an extent such that the metal pin reaches the opposing end of the bracket slot, establishing a second position. The bolt may then be tightened to so that the bracket secures the sensor module in the new position.  
         [0015]     While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.