Abstract:
Forward movement of a bicycle results when force is transfer from the chain or belt to a sprocket on a cassette. The cassette is splined to the cassette driver and causes the wheel of the bike to rotate when torque is applied from the cassette to the cassette driver. The cassette driver is typically made of a strong hard material such as steel to withstand the forces in parted thereon by the cassette. The present disclosure provide a hub configuration and method that enables the cassette driver to be made with construction of a lighter weight material such as aluminum yet still withstand the toque applied thereto.

Description:
RELATED APPLICATION 
       [0001]    This application is a continuation in part of U.S. patent application Ser. No. 15/089,998 which was filed on Apr. 4, 2016, which is incorporated herein by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    A cassette driver for a freewheel hub. 
       BACKGROUND 
       [0003]    Freewheeling bicycle hubs are generally known. For example, U.S. Pat. No. 2,211,548 to Frank W. Schwinn issued on Jun. 24, 1940 is directed to a freewheeling bicycle hub configuration. Freewheeling bicycle hubs are configured to enable rotation of the pedals to drive the rotation of the wheels while also allowing the wheels to rotate independently of the rotation of the pedals. This functionality enables the pedals of the bike to be held stationary while the wheels rotate as the bike coasts. Often freewheeling hubs are configured for geared applications that include a rear cassette. A cassette driver is a portion of the hub that supports a cassette and drives the rotation of the cassette. 
       SUMMARY 
       [0004]    Forward movement of a bicycle results when force is transferred from the chain or belt to a sprocket on a cassette. The cassette is splined to the cassette driver and causes the wheel of the bike to rotate when torque is applied from the cassette to the cassette driver. The cassette driver is typically made of a strong hard material such as steel to withstand the forces in parted thereon by the cassette. The present disclosure provides a hub configuration and method that enables the cassette driver to be constructed of a lighter weight material such as aluminum yet still withstand the toque applied thereto. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is an isometric view of a hub according to the principles of the present disclosure; 
           [0006]      FIG. 2  is a longitudinal cross-sectional view of the hub of  FIG. 1 ; 
           [0007]      FIG. 3  is a cross-sectional view of the hub along line  3 - 3  of  FIG. 2 ; 
           [0008]      FIG. 4  is a cross-sectional view of the hub along line  4 - 4  of  FIG. 2 ; 
           [0009]      FIG. 5  is an exploded assembly view of the hub of  FIG. 1 ; 
           [0010]      FIG. 6  is a first perspective view of a first embodiment of the cassette driver; 
           [0011]      FIG. 7  is a second perspective view of the embodiment of the cassette driver of  FIG. 6 ; 
           [0012]      FIG. 8  is an assembly view of the first embodiment of the cassette driver of  FIG. 6 ; 
           [0013]      FIG. 9  is a cross sectional view of the cassette driver of  FIG. 6  along line  9 - 9  of  FIG. 10 ; 
           [0014]      FIG. 10  is a cross sectional view of the cassette driver of  FIG. 6  along line  10 - 10  of  FIG. 9 ; 
           [0015]      FIG. 11  is an enlarged view of a portion of  FIG. 10 ; 
           [0016]      FIG. 12  is an enlarged view of a portion of  FIG. 8 ; 
           [0017]      FIG. 13  is a first perspective view of a second embodiment of the cassette driver; 
           [0018]      FIG. 14  is a second perspective view of the embodiment of the cassette driver of  FIG. 13 ; 
           [0019]      FIG. 15  is an assembly view of the first embodiment of the cassette driver of  FIG. 13 ; 
           [0020]      FIG. 16  is a cross sectional view of the cassette driver of  FIG. 13  along line  16 - 16  of  FIG. 17 ; 
           [0021]      FIG. 17  is a cross/sectional view of the cassette driver of  FIG. 13  along line  17 - 17  of  FIG. 16 ; 
           [0022]      FIG. 18  is a perspective view of a component of a hub shown in  FIG. 2  according to the present disclosure; 
           [0023]      FIG. 19  is a first perspective view of a third embodiment of the cassette driver; 
           [0024]      FIG. 20  is a second perspective view of the cassette driver of  FIG. 19 ; 
           [0025]      FIG. 21  is a third perspective view of the cassette driver of  FIG. 19 ; 
           [0026]      FIG. 22  is an first assembly view of the cassette driver of  FIG. 19 ; 
           [0027]      FIG. 23  is a second assembly view of the cassette driver of  FIG. 19 ; 
           [0028]      FIG. 24  is a third assembly view of the cassette driver of  FIG. 19 ; 
           [0029]      FIG. 25  is an end view of the cassette driver of  FIG. 19 ; and 
           [0030]      FIG. 26  is a cross sectional view of the cassette driver of  FIG. 19  along lines  26 - 26 . 
       
    
    
     DETAILED DESCRIPTION 
       [0031]    Referring to  FIG. 1 , a first embodiment of a hub according to the present disclosure is shown. In the depicted embodiment, the hub  10  includes a hub body  12 , an axle  14 , and cassette driver  16 . In the depicted embodiment, the hub  10  is configured to freewheel. In other words, a cassette driver  16  rotates with the hub body  12  when the wheel is driven by the cassette driver  16  and the cassette driver  16  rotates relative to the hub body  12  when the wheel is coasting (rotating and not being driven). 
         [0032]    Referring to the FIGS. generally, the configuration of hub  10  is described in greater detail. In the depicted embodiment, the hub  10  is configured for use with multiple speed bicycles (e.g., road bikes, mountain bikes, etc.) that utilize an external cassette driven by a chain. In the depicted embodiment, the axle  14  is co-axially arranged within the hub body  12 . In particular, the axle  14  extends through the hub body  12 . The axle  14  includes a first end portion  18  that is positioned within the first end portion  22  of the hub body  12  and a second opposed end portion  24  that includes a portion that extend outwardly from the second end  26  of the hub body  12 . It should be appreciate that the principles of the present disclosure can alternatively be integrated into a single speed bicycle. 
         [0033]    In the depicted embodiment, the first end portion  18  of the axle includes a shoulder  28 . The hub body  12  includes a snap ring groove  30  aligned with the shoulder  28  in a radial direction such that a snap ring  32  and the shoulder  28  cooperatively limit the axial movement of a bearing set  34  in a direction toward the second end  26  of the hub body  12 . The bearing set  34  engages an exterior surface of the axle and an interior surface of the internal cavity  56  of the hub body  12 . 
         [0034]    In the depicted embodiment, the second end portion  24  of the axle  14  is co-axially arranged within both the hub body  12  and drive end portion  48  of the cassette driver  16 . In the depicted embodiment, a portion of the second end portion  24  of the axle  14  extends into the driven end of the cassette. In the depicted embodiment, the second end of portion  24  of the axle  14  interfaces with the cassette driver  16  via bearing set  52 . 
         [0035]    In the depicted embodiment, the hub body  12  includes a one-piece construction. The hub body  12  is machined from a single piece of aluminum (e.g., aluminum 7075T651). The hub body  12  defines a longitudinal rotational axis A-A. The hub body  12  includes an internal cavity  56  that receives the axle  14  as well as the drive end portion  48  of the cassette driver  16 . The hub body  12  includes a first radially extending flange  58  located at the first end portion  22  of the hub body  12 , and a second radially extending flange  60  located at the second end of the hub body. Each of the radially extending flanges  58 ,  60  includes a plurality of spaced apart through apertures  62  that are configured to secure spokes. Adjacent the first radially extending flange  58  is a disk brake mount flange  64  configured to support a disk of a disk brake system. The external cylindrical body of the hub body  12  tapers from the second flange  60  towards the first flange  58 . In other words, the exterior diameter of the hub body  12  adjacent the second flange  60  is greater than the exterior diameter of the hub body  12  adjacent the first flange  58 . 
         [0036]    In the depicted embodiment, the wall thickness of the hub body  12  is greater in the portion that radially overlaps the drive end portion  48  of the cassette driver  16  as compared to the portion that does not overlap the cassette driver  16 . In the depicted embodiment, the internal cavity  56  of the second end portion  26  of the hub body defines two internal cylindrical surfaces. A first cylindrical surface  66  is defined as being a distance D 1  from the longitudinal rotational axis A-A, and a second cylindrical surface  68  is defined as being a distance D 2  from the longitudinal rotational axis A-A. In the depicted embodiment, D 2  is greater than D 1  and the first surface  66  is closer to the first end portion  22  of the hub body  12  than the second cylindrical surface  68 . In the depicted embodiment, the hub body is machined in a process whereby the hub body is not removed from a spindle until both the first and second cylindrical surfaces  66 ,  68  are machined. 
         [0037]    In the depicted embodiment, the cassette driver  16  includes an internal cavity  70  that extends from a drive end portion  48  to an opposed driven end portion  72 . The cavity receives the axle  14 , which extends into the drive end portion  48  of the cassette driver  16 . The cassette driver  16  defines a longitudinal axis of rotation that is coaxial and coincident with the axis of rotation A-A of the hub body  12 . 
         [0038]    In the depicted embodiment, the drive end  48  of the cassette driver  16  includes a plurality of coaxial cylindrical surfaces that are positioned within the hub body  12  opposite the internal cylindrical surfaces  66 ,  68  of the hub body  12 . In the depicted embodiment, an annular snap ring groove  76  is located in the first cylindrical surface  66  of the inner cavity  56  of the hub body  12  opposite an end face  78  of the drive end portion  48  of the cassette driver  16 . A first cylindrical surface  80  extends from the end face  78  of the cassette driver towards the driven end  72  of the cassette driver  16 . The first cylindrical surface  80  of the drive end  48  together with the first cylindrical surface  66  defines a first annular cavity that receives bearing set  82  that interfaces between the drive end  48  of the cassette driver  16  and the hub body  12 . 
         [0039]    In the depicted embodiment, a second cylindrical surface  84  having a larger diameter than the first cylindrical surface  80  extends from the first cylindrical surface  80  towards the driven end  72  of the cassette driver  16 . The second cylindrical surface  84  of the drive end  48  together with the second cylindrical surface  68  defines an annular cavity that receives a sprag clutch assembly. In the depicted embodiment, the surface finish of the second cylindrical surface  84  is less than or equal to Rz of 2.5 micrometers and has a HRC hardness of at least 56 (e.g., between 58 to 62). In the depicted embodiment, the second cylindrical surface  84  has a diameter of greater than 22 mm (e.g., 29 mm). In the depicted embodiment, the second cylindrical surface is constructed of stainless steel. 
         [0040]    In the depicted embodiment, the sprag clutch assembly includes a sprag sleeve  86 , a sprag retaining cage  88 , sprags  90 , and a tensioning band  92 . In the depicted embodiment, the surface finish of the inside surface of the sprag sleeve is less than or equal to Rz of 2.5 micrometers and the inside surface of the sprag sleeve has a HRC hardness of at least 56 (e.g., between 58 to 62). In the depicted embodiment, the sprag sleeve  86  has a diameter of less than 40 mm (e.g., 37 mm). The sprag sleeve has a height dimension that is greater than the height dimension of the sprag retaining cage  88 . The sprag sleeve  86  includes a snap ring groove that receives a snap ring that limits the axial movement of the sprag cage  88  in the axial direction towards the driven end  72  of the cassette driver. 
         [0041]    In the depicted embodiment, the sprag sleeve is constructed of a 5210 bearing race type steel which is pressed fit/interference fit into the second cylindrical surface  68  of the hub body  12 . The construction of the sprag sleeve  98  and the hub body  12  cooperatively provide the structural stiffness needed for reliable and long lasting operation of the hub despite the strong radial forces that are generated by the sprags  90 . The sprags and sprag cages used in the depicted embodiment are currently available commercially from GMN Paul Müller Industrie GmbH &amp; Co. KG. 
         [0042]    In the depicted embodiment, a third cylindrical surface  94  extends coaxially from the second cylindrical surface  84  towards the driven end  72  of the cassette driver  16 . The third cylindrical surface  94  has a diameter that is greater than the diameter of the second cylindrical surface  84 . A shoulder  96  is provided on the cassette driver  16  between the third cylindrical surface  94  and the driven end  72  of the cassette driver  16 . The third cylindrical surface  94  of the drive end  48  of the cassette driver  16  together with the second cylindrical surface  68  defines a first annular cavity that receives bearing set  98  that interfaces between the drive end  48  of the cassette driver  16  and the hub body  12 . The shoulder  96  limits axial movement of the bearing set  98  in the direction towards the driven end  72  of the cassette driver  16 . An end face of the sprag sleeve  86  limits axial movement of the bearing set  98  on the axial direction towards the first cylindrical surface  80  of the drive end  48  of the cassette driver  16 . In the depicted embodiment the third cylindrical surface  94  includes an annular o-ring groove configured to receive an o-ring that seals the interface between the third cylindrical surface  94  and the bearing set  98 . 
         [0043]    In the depicted embodiment, the internal cavity of the drive end  48  of the cassette driver includes a first cylindrical surface  100  defined by a first diameter that is greater than the diameter of the axle. The configuration results in further weight savings and strength of the cassette driver and facilitates precision manufacturing thereof. 
         [0044]    In the depicted embodiment the configuration results in a high performance hub as it has the strength and durability to withstand intense use while also being lightweight and smooth in operation. The hub body  12  is constructed of lightweight, relatively softer aluminum material, and it is designed so that it can be manufactured with high precision as the above-referenced cylindrical surfaces  66 ,  68  can be machined without detaching the hub body  12  from the chuck that holds the part during machining. The hard and robust sprag sleeve  86  is pressed into the softer aluminum. The pressing process creates a tight interference fit between the sprag sleeve  86  and cylindrical surface  68 . This interface allows the hub body  12  to work together to resist the radial forces generated by the sprags. The sprag sleeve  86  provides the hardened surface that interfaces with the sprags and also provides additional structural strength to the hub. The hub of the depicted embodiment does not require rebuilding and can operate in extreme environments including environments as cold as −50 degrees Fahrenheit. 
         [0045]    In the depicted embodiment, the sprag cage moves with the cassette driver  16 . The tensioning member (e.g., spring) on the sprag cage biases the individual sprags against the cylindrical surface  84  of the cassette driver  16  resulting in the sprag cage being essentially tension mounted to cassette driver  16 . The internal ends of the sprags contact the second external surface  84  of the cassette driver and are biased radially outwardly against a spring and extend radially slightly beyond the periphery edge of the sprag cage. This configuration results in little and light contact between the sprags and the sprag sleeve  86  during coasting, which results in a very low friction configuration as the clutch configuration is disengaged during coasting. The non-drive forces applied between the hub body  12  and the cassette driver  16  are transferred through the bearing sets  82 ,  98  that sandwich the sprag clutch assembly. 
         [0046]    In the depicted embodiment, as soon as the driven end  72  is rotated in the drive direction at a rotational speed that exceeds the rotational speed in the drive direction of the hub body  12 , the sprags engage and lock against the sprag sleeve  86  and transfer torque from the cassette driver  16  to the hub body  12 . In the depicted embodiment, the sprag clutch assembly transfers torque to drive the hub forward. However, the sprag clutch assembly is not relied on as a bearing set support the relative rotation between the cassette driver  16  and the hub body  12 . This configuration results in a clutch configuration that immediately engages when the driven end is driven. For example, in the depicted configuration the driven end cannot be rotated relative to the hub body in the drive direction more than a small amount before it fully engages and transfers torque from the cassette driver  16  to the hub body  12 , thereby causing the hub body to rotate with the cassette driver  16 . The amount of relative rotation in the drive direction, commonly referred to as play or slop, can be less than five degrees (e.g., less than two degrees, less than one degree, or one half of a degree). 
         [0047]    In the depicted embodiment, the driven end portion  72  is connected to the drive end portion. As discussed above, the drive end portion includes a plurality of coaxial cylindrical surfaces. In the depicted embodiment, the driven end portion  72  is formed of aluminum and includes a cylindrical body portion  110  with a plurality of axially extending raised splines  112  spaced apart on the cylindrical body portion  110 . In the depicted embodiment, adjacent splines define channels  134  therebetween. In the depicted embodiment the splines extend axially from a back wall  138  located at an end portion of the cylindrical body portion. The splines  112  are configured to engage a cassette comprised of sprockets and spacers. It should be appreciated that in alternative embodiments, the driven end portion is not integral connected to the drive end portion (e.g., they are separate components). 
         [0048]    In the depicted embodiment, at least one of the splines is integrally formed on the surface of the cylindrical body portion  110  of the cassette driver. The at least one spline  114  includes a drive side  116 , which including a reinforcement engagement member  118 . In the depicted embodiment, at least three of the splines  114 ,  120 ,  122  are integrally formed on the surface of the driven end portion of the cassette driver. In the depicted embodiment, all of the splines are integrally formed on the surface of the cassette driver. However, many other alternative are also possible. 
         [0049]    In the depicted embodiment, the at least three splines each includes a drive side  116 ,  124 ,  126 . Each of the drive sides of the splines includes a reinforcement engagement member  118 ,  128 ,  130 . The reinforcement engagement members can include a portion having a radius surface  132  (see  FIG. 8 ). Additionally or alternatively, the reinforcement engagement member can include an undercut surface  136  on the drive side of the spline (see  FIG. 9 ). Also, additionally or alternatively, the reinforcement member can be at least partially recessed into grooves  144  in the channel  134  between adjacent splines (see  FIG. 6 ). Additionally or alternatively, the reinforcement member can include round pin receiving aperture  142  configured to receive an end of a round pin (see  FIGS. 10 and 11 ). Additionally or alternatively, the reinforcement engagement member is configured to receive a reinforcement member radially and secure the reinforcement member adjacent the drive side of the spline (see  FIG. 8 ). Alternatively, reinforcement engagement member is configured to receive a reinforcement member axially and secure the reinforcement member adjacent the drive side of the spline (see  FIGS. 10 and 11 ). It should be appreciated that many configurations are possible. 
         [0050]    In the depicted embodiment, the drive end portion of the cassette drive includes at least one reinforcement member  140 . In the depicted embodiment, the reinforcement member has a HRC hardness of at least at least 56 (e.g., between 58 to 62) and is engaged with the reinforcement engagement member. In the depicted embodiment, the reinforcement member is a round steel pin. In some embodiments, the round pin can be snap into engagement with the reinforcement engagement member ( FIG. 8 ). In some embodiments, the end of the reinforcement member (e.g., round pin) is pressed into an aperture  142  on the back wall  138  ( FIGS. 10 and 11 ). In the depicted embodiment, the distance from a rotational axis to a far edge of the reinforcement member does not exceed the distance from the rotational axis to a top surface of the spline (i.e., the reinforcement member is flush with or less than flush with the top of the spline). 
         [0051]    The present disclosure also provides a method of manufacturing a hub. The method includes the step of machining a cassette driver from an aluminum body. The step of machining includes forming a drive end portion  48  and a driven end portion  72 , wherein the drive end portion includes a plurality of coaxial cylindrical surfaces and the driven end portion includes a cylindrical body portion including a plurality axially extending raised splines  112  spaced apart on the cylindrical body portion  110 , wherein the splines define a plurality of channels  134  between adjacent spline. In the depicted embodiment, at least one spline includes a drive side, the drive side including a reinforcement engagement member  140 . 
         [0052]    The method can further include the step of securing a reinforcement member to the reinforcement engagement member. The method can further include connecting a steel insert  150  over the drive end portion of the cassette driver and machining the steel insert thereafter. The step of connecting the steel insert can include the step of pressing the steel insert into engagement with the drive end portion of the cassette driver or threading the insert thereon. The step of connecting the steel insert can include the step of axially aligning tangs with notches in the drive end of the cassette driver. The tangs once engaged with the notches prevent relative rotation of the steel insert relative to the cassette driver. In the depicted embodiments the steel insert include two tangs where are opposed and have curved exterior and interior surfaces. It should be appreciated that many other configurations are possible including for example configuration with more or less tangs (e.g., four tangs). The step of machine the steel insert after connecting it to the steel driver can be used to ensure its concentricity with the other cylindrical surface of the drive end portion  48  of the cassette driver. Many other connection methods are also possible. 
         [0053]    Referring to  FIGS. 19-26 , an alternative embodiment of the cassette driver is shown. In the depicted embodiment, the cassette driver  160  includes splines  162 ,  164  each includes a longitudinal side  166 ,  168 ,  170 ,  172 . Opposed sides of the adjacent splines includes a reinforcement engagement members. The reinforcement engagement members can include a portion having a radius surface. Additionally or alternatively, the reinforcement engagement member can include an undercut surface on the longitudinal side of the spline. It should be appreciated that many configurations are possible. 
         [0054]    In the depicted embodiment, the drive end portion of the cassette drive includes at least one reinforcement member  180 . In the depicted embodiment, the reinforcement member has a HRC hardness of at least at least 56 (e.g., between 58 to 62) and is engaged with the reinforcement engagement member. In the depicted embodiment, the reinforcement member  180  is a steel spring clip having a circular cross section. In the depicted embodiment, the spring clip  180  includes a first leg  190  and a second leg  192  that are connected to each other via a base portion  182 . In some embodiments, the spring clip  180  is snap or axially slide into engagement with the reinforcement engagement member. In the depicted embodiment the spring force of the spring clip  180  acting outwardly against the longitudinal sides  168 ,  170  of the adjacent splines  162 ,  164  retains the spring clip in place against the opposed longitudinal surfaces of adjacent splines. 
         [0055]    In the depicted embodiment, the distance from a rotational axis to a far edge of the reinforcement member does not exceed the distance from the rotational axis to a top surface of the spline (i.e., the reinforcement member is flush with or less than flush with the top of the spline). 
         [0056]    In the depicted embodiment, the base portion  182  of the spring clip  180  is received within an undercut portion  184  of a rear shoulder  186  that creates a cavity  188 . The based portion  182  facilitates retention of the spring clip  180 . In the depicted embodiment, the spring clip  180  can be fitted onto the cassette driver prior to installing the cassette thereon. In the depicted embodiment, the spring clip is can be assembled onto the cassette drive during manufacturing thereof prior to being ship and sold. 
         [0057]    In alternative embodiment, the spring clip could be installed onto the cassette driver during the assembling the bicycle or even after the cassette is installed on the cassette driver. In the depicted embodiment wherein the cassette driver is installed first, the spring clip can be installed with the ends retained in the cavity  188  and the based  182  located at the distal end of the cassette driver. It should be appreciated that many alternative configurations are possible. 
         [0058]    In the depicted embodiment, the cassette drive includes three spring clips that are spaced apart on the cassette driver. In the depicted embodiment, the spring clips are retained between alternating splines. In the depicted embodiment, the spring clips are evenly spaced around the periphery of the cassette body approximately 120 degrees apart. It should be appreciated that many alternative configurations are possible. 
         [0059]    The above specification, examples, and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.