Patent Publication Number: US-7216621-B2

Title: Double sheave accessory drive pulley

Description:
FIELD OF THE INVENTION 
     The present invention relates to an automotive accessory drive pulley and, more particularly, to a double drive pulley assembly adapted to drive a plurality of automotive vehicle accessories and support loads associated therewith. 
     BACKGROUND OF THE INVENTION 
     Automotive engine accessories such as generators, air conditioning compressors, and power steering pumps are typically driven by engine torque. The torque is transmitted through a serpentine belt wrapped around an engine crankshaft pulley and routed around a series of additional pulleys mounted on the front of the engine accessories. It is critical to position the accessories on the engine to ensure adequate belt wrap at the pulleys to provide maximum power transmission throughout all driving conditions. If the belt wrap is insufficient, the belt may slip under certain conditions. Belt slippage results in reduced accessory performance, reduced belt durability, and increased noise. Additionally, it is critical to ensure that the belt or belts are adequately taught to provide maximum power transmission and to minimize belt slippage. However, high belt tension results in high radial loads being transferred to the crankshaft and other pulleys. These radial loads are then transferred to the engine accessory drive shafts, which can ultimately reduce the useful life of the accessories. 
     Further design challenges relate to the desire of Original Equipment Manufacturers to increase the number of engine accessories, thereby increasing the complexity of these belt and pulley systems, while reducing the envelope available for the engine and the engine accessories. One attempt to overcome these challenges includes driving a plurality of belts directly from the crankshaft, thereby providing direct power to a plurality of accessories. Unfortunately, vehicle steering, suspension, or any other automotive system or systems may occupy the packaging space and preclude the use of a plurality of drive belts directly driven by the crankshaft. 
     SUMMARY OF THE INVENTION 
     The present invention provides a pulley assembly adapted to transmit torque from a drive pulley to first and second driven accessories. The pulley assembly generally includes a housing and an auxiliary drive component. The auxiliary drive component is rotatably supported by the housing and adapted to be coupled to the first driven accessory. The auxiliary drive component includes first and second annular drive surfaces. The first drive surface is adapted to be drivingly coupled to the drive pulley and the second drive surface is adapted to be drivingly coupled to the second driven accessory. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of an exemplary pulley configuration including a double pulley assembly in accordance with the present invention; 
         FIG. 2  is a side cross-sectional view of an exemplary embodiment of a double pulley assembly in accordance with the present invention; and 
         FIG. 3  is a side cross-sectional view of an alternative embodiment of a double pulley assembly in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the scope of the invention, its application, or its uses. 
     Referring to  FIG. 1 , an exemplary pulley configuration for an automotive vehicle engine  10  is illustrated at reference numeral  12 . The configuration generally includes a crankshaft pulley  14 , an air conditioner compressor  16  having a compressor pulley  18 , a linear tensioner  20  having a tensioner pulley  22 , a power steering pump  24  having a pump pulley  26 , an idler pulley  28 , a supercharger  30  having a supercharger pulley  32 , a serpentine belt  34 , and an auxiliary belt  36 . The pump pulley  26  illustrated in  FIG. 1  includes a double sheave pulley assembly  100  in accordance with the present invention. The double sheave pulley assembly  100  includes a first pulley portion  100   a  and a second pulley portion  100   b . The serpentine belt  34  wraps around the crankshaft pulley  14 , the tensioner pulley  22 , the compressor pulley  18 , and the first pulley portion  100   a  of the pump pulley  26 . The auxiliary belt  36  wraps around the second pulley portion  100   b  of the pump pulley  26 , the idler pulley  28 , and the supercharger pulley  32 . While the pulley configuration and accessories described herein generally relate to automobiles, the double pulley assembly of the present invention may also be applied to other motorized devices such as boats, snowmobiles, tractors and the like. 
     During operation, the serpentine belt  34  transfers torque produced by an engine  10 , via the crankshaft pulley  14 , to the air conditioner compressor  16  and power steering pump  24 . In addition, the auxiliary belt  36  transfers drive torque from the crankshaft pulley  14  to the supercharger  30 , via the pump pulley  26 . It should be appreciated that while the double sheave pulley assembly  100  is illustrated as being employed on the power steering pump  24 , alternate locations are within the scope of the present invention. For example, the double pulley assembly may be coupled to a water pump, a generator, a hydraulic pump, an air conditioning compressor, a supercharger, or another accessory not listed. 
       FIG. 2  depicts the double sheave pulley assembly  100  generally including a housing  102  and an auxiliary drive component  104 . The housing  102  is adapted to be substantially stationarily mounted to the vehicle engine  10 . The auxiliary drive component  104  is rotatably supported by the housing  102 . The auxiliary drive component  104  is drivingly coupled to an input shaft  105  of the power steering pump  24 . 
     The housing  102  includes a body portion  106  and a flange portion  108 . The body portion  106  includes a generally cylindrical interior surface  110  and a generally conical exterior surface  113 . The flange portion  108  includes a plurality of recesses  107  that receive a plurality of fasteners  109  to mount the double sheave pulley assembly  100  to the engine  10 . 
     The auxiliary drive component  104  includes a shaft  112  and a rotary member  114 . The shaft  112  includes a first end  112   a  having a threaded internal bore  116  and a second end  112   b  having an external flange  118  and a plurality of internal teeth  120 . The rotary member  114  includes a pulley portion  122  and a base portion  124 . The pulley portion  122  is generally cylindrical in shape and includes a first plurality of annular grooves  126  defining the second pulley portion  100   b  and a second plurality of annular grooves  128  defining the first pulley portion  100   a . The base portion  124  is a generally circular plate having an aperture  130 . The aperture  130  receives the first end  112   a  of the shaft  112  to support the rotary member  114  thereon. 
     The shaft  112  supports the auxiliary drive component  104  for rotation relative to the housing  102 . A first bearing  132  is positioned at the first end  112   a  of the shaft  112 . A second bearing  134  is positioned at the second end  112   b  of the shaft  112 . The first bearing  132  includes an inner race  136  and an outer race  140 . The second bearing  134  includes an inner race  138  and an outer race  142 . Outer race  140  is press-fit within a counter-bore  143  of the housing  102 . Outer race  142  is press-fit within a counter-bore  145  of the housing  102 . The inner races  136 ,  138  are slip-fit on the shaft  112 . A shaft sleeve  144  is positioned on the shaft  112  between the first bearing  132  and the second bearing  134  to space apart the first  132  and second  134  bearings a predetermined distance. 
     A threaded fastener  146  threadably engages the threaded internal bore  116  of the shaft  112  to maintain axial engagement of the components of the assembly  100 . A head  148  on the threaded fastener  146  engages a washer  150 , which in turn engages the base portion  124  of the rotary member  114  on the auxiliary drive component  104 . The base portion  124  engages the inner race  136  of the first bearing  132 . The inner race  136  of the first bearing  132  engages the shaft sleeve  144 . The shaft sleeve  144  engages the inner race  138  of the second bearing  134 . Finally, the inner race  138  of the second bearing  134  engages the external flange  118  formed on the second end  112   b  of the shaft  112 . Hence, the threaded fastener  146  clamps the rotary member  114 , the first bearing  132 , the shaft sleeve  144 , and the second bearing  134  between the external flange  118  and the washer  150  to provide proper alignment and support for rotary member  114 . 
     During operation, the plurality of internal teeth  120  on the second end  112   b  of the shaft  112  are splined to a plurality of external teeth  152  formed on the input shaft  105 . A drive belt  34  (shown in  FIG. 1 ), such as a serpentine belt, engages the second plurality of annular grooves  128  formed on the pulley portion  122  of the rotary member  114 . An auxiliary belt  36  (shown in  FIG. 1 ) engages the first plurality of annular grooves  126  formed on the pulley portion  122  of the rotary member  114 . Due to belt wrap and belt tension, radial loads are often generated while one or both of the above-described belts deliver torque to the rotary member  114 . Transmission of these radial loads to the input shaft  105  of the vehicle accessory can substantially decrease the useful life of the vehicle accessory. Therefore, the housing  102  reacts the radial loads experienced by the rotary member  114  to ensure that only torque is transmitted to the input shaft  105  of the vehicle accessory. 
       FIG. 3  depicts an alternative double sheave pulley assembly  200  generally including a housing  202  and an auxiliary drive component  204 . The housing  202  is adapted to be substantially stationarily mounted to a vehicle engine  10  (shown in  FIG. 1 ). The auxiliary drive component  204  is rotatably supported by the housing  202 . The auxiliary drive component  204  is drivingly coupled to an input shaft  205  of the power steering pump  24 . 
     The housing  202  includes a body portion  206  and a flange portion  208 . The body portion  206  has a substantially cylindrical interior surface  210  and a substantially conical exterior surface  212 . The flange portion  208  includes a plurality of recesses  214  that receive a plurality of fasteners  216  for being mounted to the engine  10 . 
     The auxiliary drive component  204  is a one piece member including a shaft portion  218 , a pulley portion  220 , and a base portion  222 . The shaft portion  218  is rotatably supported within the housing  202 , thereby rotatably supporting the pulley portion  220  outside the housing  202 . The shaft portion  218  includes an outer end  218   a  and an inner end  218   b . The inner end  218   b  includes a plurality of internal teeth  224  and an annular channel  226 . The pulley portion  220  includes a first plurality of annular grooves  228  and a second plurality of annular grooves  230 . The base portion  222  is a substantially circular plate that provides the radial transition between the shaft portion  218  and the pulley portion  220 . 
     A first bearing  231  is positioned at the outer end  218   a  of the shaft portion  218 . A second bearing  232  is positioned at the inner end  218   b  of the shaft portion  218 . The first bearing  231  includes an inner race  234  and an outer race  238 . The second bearing  232  includes an inner race  236  and an outer race  240 . Outer race  238  is press-fit within counter-bore  242  of the housing  202 . Outer race  240  is press-fit within counter-bore  244  of the housing  202 . The inner races  234 ,  236  are slip-fit on the shaft portion  218 . A shaft sleeve  246  is positioned between the bearings  231 ,  232 . A snap ring  248  engages the annular channel  226  formed in the inner end  218   b  of the shaft portion  218 . 
     During assembly, the bearings  231 ,  232 , shaft sleeve  246 , and housing  202  are assembled before applying the snap ring  248 . This aforementioned assembly is pre-loaded in the axial direction and then the snap ring  248  is applied to the annular channel  226 . The snap ring  248 , thus, provides a clamping force to the components of the assembly  200 . The snap ring  248  engages the inner race  236  of the second bearing  232 . The inner race  236  of the second bearing  232  engages the shaft sleeve  246 . The shaft sleeve  246  engages the inner race  234  of the first bearing  231 . The inner race  234  of the first bearing  231  engages a shoulder  250  formed on an inside surface of the base portion  222  of the auxiliary drive component  204 . 
     Operation of this alternative embodiment of the double sheave pulley assembly  200  is similar to that of the first embodiment described above. The plurality of internal teeth  224  on the inner end  218   b  of the shaft portion  218  are engagingly splined to a plurality of external teeth  252  on the input shaft  205  of the vehicle accessory. A drive belt  34  (shown in  FIG. 1 ) engages the second plurality of annular grooves  230  formed on the pulley portion  220  of the auxiliary drive component  204 . An auxiliary belt  36  (shown in  FIG. 1 ) engages the first plurality of annular grooves  228  formed on the pulley portion  220  of the auxiliary drive component  204 . The component assembly just described assures that a bending moment is not imported onto the input shaft  205  of the vehicle accessory. As described above, with reference to the first embodiment, the housing  202  reacts the radial loads generated by one or both of the belts delivering torque to the pulley portion  220  of the auxiliary drive component  204 . 
     The description of the invention is merely exemplary in nature and, thus, 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.