Abstract:
A window regulator assembly particularly adapted for motor vehicle applications having a pulley assembly featuring snap in insulation of a pulley ring into a pulley housing. The pulley housing features the clearance area and a number of retention tabs and hooks which enable the pulley ring to be snap fit into position. The assembly may be implemented with a discrete window regulator or as part of a modular inner door plate as well as and for other applications.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application No. 62/290,733, filed on, filed on Feb. 3, 2016. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a pulley joint assembly potentially suited for various applications but in a preferred implementation is utilized in an automotive window regulator assembly. 
     BACKGROUND 
     Passenger car and a light truck motor vehicles feature movable side door glass. A mechanism is required to move the glass between the upper closed position and the lower opened position. These mechanisms are generally known as window regulators. Window regulators can be manually operated, or can be driven by a power actuator, most commonly employing an electric motor. One type of window regulator uses a pulley arrangement having a metal cable wrapped around a drum driven by an electric motor. These devices use a carrier movable along a guide rail which engages the door glass which is a driven by the metal cable to control its motion. 
     The pulley components provided for cable driven window regulator systems are available in numerous configurations. A typical arrangement is to provide a stud or shaft which acts as a bearing journal for supporting and permitting rotation of the pulley. The drive cable is wrapped around the outer perimeter of the pulley wheel. These devices work well and are implemented in a wide range of machines, articles and mechanisms. Despite the satisfactory performance of conventional pulley arrangements, there is constantly a desire to reduced cost, simplify assembly, and reduce weight of automotive components, while providing a desirable durability, low warranty claims, and compliance with performance requirements. This invention is related to a pulley joint assembly which addresses the above-referenced desirable attributes. 
     SUMMARY 
     The pulley joint assembly in accordance with the present invention utilizes a simple pulley arrangement which is snap-fit into a pulley housing. The joint assembly includes features for maintaining the pulley in an assembled condition while providing required performance attributes. The described arrangement may be implemented with a conventional guide rail type window regulator, or in an alternative implementation, can be integrated into a door module structure. Moreover other applications of the described pulley joint assembly in various structures and machines are available. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a window regulator assembly incorporating a pulley joint assembly in accordance with the present invention; 
         FIG. 2  is an exploded view of the pulley joint assembly components; 
         FIGS. 3A and 3B  are enlarged illustrations of the pulley joint assembly; 
         FIGS. 4A and 4B  are pictorial views illustrating an assembly process of the pulley ring into the pulley joint housing; 
         FIGS. 5A and 5B  illustrate the completed assembly condition of the pulley joint assembly; 
         FIG. 6  is a top view of pulley assembly showing contact and clearance segments of the bearing post; 
         FIG. 7A  is a cross-sectional view of the pulley joint assembly taken along line  7 A- 7 A of  FIG. 6  and  FIG. 7B  is an elongated view taken from  FIG. 7A ; and 
         FIG. 8A  is a side view of a module plate incorporating the pulley joint assembly of the present invention, and  FIG. 8B  is an enlargement from  FIG. 8A . 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIG. 1  window regulator assembly  10  is illustrated, which includes as principal components, guide rail  12 , window carrier  14 , pulley assembly  16 , motor drive assembly  18 , and drive cable  20 . Guide rail  12  is typically made from sheet-metal stock fabricated by a stamping or rolling process, or as an extrusion. Window carrier  14  is caused to travel up and down along guide rail  12  and includes a window clamp arrangement which attaches to the lower edge of the vehicle side door glass (not illustrated). Pulley assembly  16  is positioned at the top of guide rail  12  and acts to redirect and tension drive cable  20 . Motor drive assembly  16  is powered electrically and includes internal reduction gears and a cable drum to move drive cable  18 . Drive cable  20  wraps around pulley assembly  16  at the top of the assembly and wraps around the drive pulley which is part of motor drive assembly  18 . Ends of drive cable  20  terminate at window carrier  14 . 
     Motor drive assembly  18  is shown in  FIG. 1  affixed to the bottom of guide rail  12  but could be positioned at other locations depending on application requirements. Similarly, pulley assembly  16  is shown at the top of guide rail  12  but may be implemented in various other positions depending on the application. Window regulator assembly  10  is shown as a single rail type system. Alternate implementations may use a pair of separated guide rails provided for control of the movable glass or other panel, based on application requirements. 
     This invention is particularly related to the design configuration of pulley assembly  16 . As noted previously, such a pulley arrangement may be found in numerous automotive and other vehicle applications and other mechanisms and devices. Although this description treats pulley assembly  16  as part of window regulator assembly  10 , the pulley assembly may be implemented in such alternative applications. For example pulley assembly  16  is described as usable for controlling the motion of side door glass, but could be readily implemented for other motor vehicle movable panels including closure panels. 
     With particular reference to  FIGS. 2A, 2B, 3A and 3B , features of components of pulley assembly  16  are illustrated. Pulley ring  22  is hoop shaped with an outer external grooved perimeter  24  for receiving and guiding drive cable  20 . Inside cylindrical bearing surface  26  is provided for allowing rotation of pulley ring  22 , as will be described in further detail. Between perimeter  24  and bearing surface  26  is a reduced thickness circular central hub portion  25 . Pulley ring  22  is preferably formed of a polymeric resin material. 
     Pulley housing  28  is an injection molded unitary plastic component and features slot  30  to enable it to be slid on and attached to the upper end of guide rail  12 , as best illustrated in  FIG. 2 . Once assembled, a locking feature may be implemented to maintain the components in an assembled condition. For example, a pierced hole or tab formed in guide rail  12  can be provided to interact with an interlocking feature of pulley housing  28 , or a discrete fastener may be used for attachment of the components. Pulley housing  28  further integrally forms projecting bearing post  32  within a circular clearance area  34  provided for accommodating pulley ring  22  for rotation. Projecting from bearing post  32  is retention tab  36  which extends in a radially outward direction to overlie a portion of clearance area  34 . Retention tab  38  is also provided which is positioned radially outside clearance area  34  and extends in a radially inward direction toward bearing post  32  and overlies clearance area  34 . An additional tab  40  extends from is supported by flexible arm  42 , and in a normal relaxed condition, positions tab  40  to project radially inwardly to overlie circular clearance area  34 . In this illustrated embodiment, central clearance bore  44  is provided at the center of bearing post  32  and receives bolt  46  which is used to fasten the upper end of the unit to associated structure. Retention tabs  36  and  40  confront each other and are positioned along a radial line vertical with respect to the top of the assembly and tension applied by the drive pulley, and tab  38  is located at a diametrically opposed radial position from tabs  36  and  40 . 
     Now with reference to  FIGS. 4A, 4B, 5A and 5B , additional design features and an assembly process for pulley assembly  16  is described. As shown in  FIGS. 4A and 4B , in a first assembly step, pulley ring  22  is positioned over bearing post  32  and its upper edge is placed in the gap between tabs  36  and  40 . As shown pulley ring  22  is tipped from the plane of its final installed position. Tab  40  is deflected as shown in  FIG. 5A  and this portion of the ring  22  is placed in position. Thereafter, the bottom edge of ring  22  closest to hook  38  can be displaced over tab  38  and placed into its final assembled condition. Arm  42  resiliently biases tab  40  to maintain pulley ring  22  in its installed condition, interlocked with tabs  36 ,  38  and  40  which overlie circular clearance area  34  and trap the pulley ring in position. Bearing post  32  is shaped such that an upper portion  48  makes direct contact with pulley ring bearing surface  26  over an arcuate contact surface when tension upon is applied by drive cable  20 , whereas lower clearance segment  50  is provided to allow vertical displacement of pulley ring  22  during the installation process, as described previously. A clearance gap  53  shown in  FIG. 6  allows pulley ring  22  to be displaced over retention tab  36  during installation. During operation of window regulator assembly  10 , tension on drive cable  22  presses pulley ring  22  against the bearing portion of bearing post  32 . 
     Assembly of pulley ring  22  and pulley housing  28  may occur before or after the assembly is affixed to guide rail  12 . In the embodiment described above, bolt  46  is provided to support the upper end of regulator assembly  10  to an associated structure. However, bolt  46  is not provided to act as a bearing component for pulley ring  22 . In an alternate design without bolt  46 , the central area of pulley housing  28  can be solid, with other features provided for supporting window regulator assembly  10 . 
       FIGS. 7A  and &amp;B illustrate a feature for reducing friction in the sliding contact between pulley bearing surface  26  and bearing post  32 . As shown by the figures, the bearing surface  26  may be relieved or chamfered from a cylindrical surface such that contact does not occur along its entire axial length but is rather concentrated to a line of contact  52 . Reduction of the contact area may provide lower friction, allowing more free movement of pulley ring  22  during operation of the window regulator assembly  10 . 
       FIGS. 8A and 8B  illustrate an embodiment of window regulator assembly  52  in which pulley assembly  26  is integrated into a module plate  56  which provides for mounting of various hardware components or functional features of the regulator assembly  54 . Such implementations may not require a discrete guide rail  12  and the features of pulley housing  28  may be molded into a larger module plate provided for the other functions described above. The regulator assembly shown in  FIG. 8A  has its motor drive assembly  18   a  at a central location with a pair of pulley assemblies  16   a  positioned at the top and bottom of the guide rail  12   a , as an example of alternate implementations of pulley assembly  16 . Pulley assemblies  16   a  are functionally identical to assembly  16  described previously. Guide rail element  12   a  can be molded as part of module plate  56 , or can be made of a metal component attached to the module plate or molded in position. Pulley housing  28   a  may be separately formed and affixed to module plate  56 , or its features can be directly molded as an integral feature of the module plate. 
     While the above description constitutes the preferred embodiment of the present invention, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope and fair meaning of the accompanying claims.