Abstract:
A guide pin assembly for a CVT variator includes a retainer and a guide pin coupled to the retainer. The retainer provides at least three functions for the guide pin: pilot, orientation and retention. The guide pin provides lateral and axial constraints to a chain guide through which a chain extends.

Description:
RELATED APPLICATION  
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 62/034,873, filed on Aug. 8, 2014, the entire contents of which are incorporated herein by reference. 
     
    
     FIELD  
       [0002]    The present disclosure relates to continuously variable transmissions. More specifically, the present disclosure relates to a guide pin assembly for continuously variable transmissions. 
       BACKGROUND  
       [0003]    The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
         [0004]    Many modern motor vehicle automatic continuously variable transmissions (CVT) utilize chain and pulleys to achieve a desired gear ratio. The CVT chain drive is an advancement in automatic transmissions that provide increased efficiency and robustness. To reduce noise, vibration and harshness from the chain and pulley assemblies, chain guides are employed. For example, chain guides are typically positioned in the two regions where the chain spans between a pair of pulleys. During the manufacturing of the CVTs, guide pins may be employed to aid in the assembly of the chain guides in the CVTs 
         [0005]    Accordingly, there is a need for a guide pin assembly that facilitates high volume production of CVTs with the chain guides. 
       SUMMARY  
       [0006]    The present invention provides a guide pin assembly for a CVT variator. The guide pin assembly includes a retainer and a guide pin coupled to the retainer. The retainer is also coupled to a housing portion of the CVT with an attachment mechanism such as, for example, a bolt. The retainer provides at least three functions for the guide pin: pilot, orientation and retention. The guide pin provides lateral and axial constraints to a chain guide through which a chain extends. 
         [0007]    Further features, advantages and areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS  
         [0008]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the views. In the drawings: 
           [0009]      FIG. 1  is a perspective view of a chain and pulley assembly for a CVT in accordance with the principles of the present invention; 
           [0010]      FIG. 2A  is a top view of the chain and pulley assembly shown in  FIG. 1 ; 
           [0011]      FIG. 2B  is a close-view of a chain guide and guide pin assembly for the chain and pulley assembly shown in  FIGS. 1 and 2A ; 
           [0012]      FIG. 2C  is a partial cross-sectional view of the chain guide and guide pin assembly shown in  FIG. 2B ; 
           [0013]      FIG. 3  is a perspective view of a pair of guide pin assemblies attached to a housing portion of the CVT; 
           [0014]      FIG. 4  is a perspective view of the pair of guide pin assemblies; 
           [0015]      FIG. 5  is a close-up view of a single guide pin assembly; and 
           [0016]      FIG. 6  is a close-up view of a guide pin of the single guide pin assembly. 
       
    
    
     DETAILED DESCRIPTION  
       [0017]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
         [0018]    Referring now to the drawings, a chain and pulley assembly for a CVT embodying the principles of the present invention is illustrated in  FIGS. 1  and  2 A and designated at  10 . The assembly  10  includes a pair of pulleys  12  and  14  rotationally coupled to a housing portion  16 . A chain  18  encircles the pulleys  12  and  14  such that rotation of one pulley results in the rotation of the other pulley. A pair of chain guides  20 A and  20 B are positioned between the pulleys  12  and  14  and couple with respective guide pin assemblies  22 A and  22 B. 
         [0019]    Each chain guide  20 A and  20 B includes a sleeve  28  ( FIGS. 2B and 2C ) through which the chain  18  extends. When the assembly  10  is being assembled together, certain amount of slack in the chain  18  allows the chain  18  and the chain guides  20 A and  20 B to move away from the pulleys  12  and  14  as indicated by the arrows  24 . Each chain guide  20 A and  20 B includes a block portion  38  connected to the sleeve  28 . A pair of spaced apart U-shaped extensions  34  and  32  extends from a top section  42  and a bottom section  40  of the block portion  38 , respectively, towards respective guide pin assemblies  22 A and  22 B. Each U-shaped extension  32  and  34  includes an interior  30  that defines a cutout region  36 . The cutout region  36  engages with a respective guide pin assembly  22 A and  22 B during the assembly process as the chain guides  20 A and  20 B are directed towards the guide pin assemblies  22 A and  22 B as indicated by the arrows  26 , thereby, restraining inward lateral movement of the chain guides  20 A and  20 B. 
         [0020]    Referring also to  FIGS. 3 and 4 , each guide pin assembly  22 A and  22 B includes a retainer  44  and a guide pin  46  that is coupled to the retainer  44 . The retainer  44  includes a flange portion  49  through which a bolt  45  extends to attach the retainer  44  to the housing portion  16 . The guide pin  46  includes a top axial stop  48  and a bottom axial stop  50  spaced apart from the top axial stop  48 . 
         [0021]    When assembled, each guide pin  46  resides in the cutout region  36  of a respective chain guide  20 A and  20 B. Engagement between the guide pins  46  and the chain guides  20 A and  20 B prevent further lateral movement of the chain guides  20 A and  20 B during the manufacturing process of the assembly  10  as well during the operation of the assembly  10 . Further, engagement between the top axial stop  48  and the top U-shaped extension  34  and engagement between the bottom axial stop  50  and the bottom U-shaped extension  32  limits the up and down axial movement of the chain guides  20 A and  20 B, that is, movement of each chain guide  20 A and  20 B parallel to the longitudinal axis of each guide pin  46 . Hence, during the operation of the assembly  10 , axial movement of the chain guides  20 A and  20 B, and hence the chain  18 , is limited by the axial stops  48  and  50  of the guide pins  46 , inward lateral movement of the chain guides  20 A and  20 B and the chain  18  is limited by the engagement between the chain guides  20 A and  20 B and the guide pins  46 , and outward lateral movement of the chain guides  20 A and  20 B and the chain  18  is limited by the tension of the chain  18 . 
         [0022]    Referring specifically to  FIG. 4 , each retainer  44  includes a guide stub  47  that extends from the bottom of the flange portion  49  into the housing portion  16  such that together with the bolts  45  ensure proper orientation of the retainer  44  with respect to the housing portion  16 . One or both guide pins  46  can include a feed  52  that provides lubrication, such as, for example, oil, to the chain  18  and the pulleys  12  and  14 . 
         [0023]    Referring now to  FIGS. 5 and 6 , each guide pin  46  includes semi-circular regions  54  and  55 , a tab  56  and a cylindrical region  58 . The cylindrical region acts  58  as a pilot pin to guide the guide pin  46  into a bore of the retainer  44  when the guide pin  46  and the retainer  44  are being coupled together. The semi-circular regions  54  and  55  allow rotational movement of the guide pin  46  about the longitudinal axis of the guide pin  46  and within the bore of the retainer  44  for proper orientation of the axial stops  48  and  50 . After the guide pin  46  has been properly positioned and orientated, the tab  56  is engaged with a notch  60  within the bore of the retainer  44  which prevents the de-coupling of the guide pin  46  from the retainer  44 , that is, provides retention of the guide pin  46  within the retainer  44 . Note that dampening material  51  may be placed in the housing portion  16  beneath the retainer  44  to limit the transmission of vibrations between the guide pin assemblies  22 A and  22 B and the housing portion  16 . 
         [0024]    The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.