Abstract:
A cage nut assembly is provided having a nut with a body and depending base. The body and base define a bore through the body and base. A cage is disposed about at least a portion of the nut. The cage enables a limited range of movement for the nut within the cage and defines an aperture coaxial with the bore.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/421,759, filed on Oct. 28, 2002. The disclosure of the above application is incorporated herein by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention relates generally to a fastener and, more particularly, to an encaged, threaded fastener.  
         BACKGROUND OF THE INVENTION  
         [0003]    With ever increasing design demands, flexibility and adaptivity of unibody construction is increasingly required in order to provide vehicles that meet broader customer needs. Increases in the number of components and structures which are coupled to the unibody construction have led designers to consistently add threaded fasteners to the unibody frame. Variation in manufacturing tolerances require that the fastener couple to the unibody frame in a way which allows a degree of positional adjustment during final assembly. This positional adjustment is provided by using a female fastener, which is an encaged fastener. Typically, this takes the form of a nut encaged in a structure that is attached to the inner body frame. The cage is configured so as to provide the nut with a range of movement so that when a component is coupled to the frame, the alignment of the component and frame can be adjusted until they meet manufacturing standards.  
           [0004]    Very large variations in vehicle manufacturing tolerances, however, significantly increase the possible loading on fasteners, thus requiring larger and heaver fastening systems be used. This increase in fastener weight leads vehicle manufactures to make costly weight decreases in other portions of the vehicle to maintain government fuel efficiency standards. Accordingly, a need exists for a fastener with decreased weight and improved strength.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention provides a caged fastener assembly. In another aspect of the present invention, the fastener is a cage nut assembly which has a nut with a body and depending base. A further aspect of the present invention provides a cage disposed about at least a portion of the nut. In yet another aspect of the present invention, a transition thickness in a fastener is greater than a body and/or base thickness.  
           [0006]    Advantages of the present invention over conventional constructions include an ability to span large gaps without nut deformation which reduces part failures and improves part reliability. 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  
       [0007]    The greatest advantage of the present invention will become apparent to one skilled in the art upon reading the following specification and by reference to the drawings in which:  
         [0008]    [0008]FIG. 1 is a perspective view of the cage nut fastener in its unassembled condition according to the principles of the present invention;  
         [0009]    [0009]FIG. 2 is a perspective view of the cage nut fastener of the present invention in its assembled configuration;  
         [0010]    [0010]FIG. 3 a  is a cross-sectional view of the cage nut fastener in FIG. 2, taken along line  3 - 3  of FIG. 2, showing the first embodiment for the through bore of the cage nut fastener of FIG. 1;  
         [0011]    [0011]FIG. 3 b  is a cross-sectional view, like that of FIG. 3 a , showing an alternative embodiment cage nut fastener;  
         [0012]    [0012]FIG. 4 is a perspective view of the preferred embodiment of a cage nut fastener in its unassembled condition according to the principles of the present invention;  
         [0013]    [0013]FIG. 5 is a perspective view of the cage nut fastener of FIG. 4 in its assembled configuration; and  
         [0014]    [0014]FIG. 6 is a cross-sectional view of the cage nut fastener in FIG. 5 showing the relationship of the fasteners and attached parts.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]    The following description of the preferred embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0016]    The present invention is generally related to a fastener for use in applications which require a fastener to span large unsupported sections with minimal deflection. In this regard, the fastener will be described in the context of a cage nut fastener for use in joining sections of an automotive vehicle component, such as a truck bed or, alternately, an engine mount. However, it is to be understood that the principles embodied herein are equally applicable to the joining of other types of structures. In addition, it is to be understood that the fastener disclosed may function according to the principles of this invention with or without a cage, although various advantages of the present invention may not be achieved.  
         [0017]    With reference now to FIGS.  1 - 3   b , a first alternate embodiment of a cage nut fastener  10  is shown. The cage nut fastener  10  includes a nut  12  and a cage  14 . The nut  12  has a main body  16 , a base  18  and a through bore  20  extending through the main body  16  and the base  18 . The main body is generally conical in nature. The height H of the main body  16  may vary depending on the particular application, but is generally 1.5 to 2.5 times the thickness T of the base  18 . The base  18  of the nut  12  is generally square in shape, however any suitable shape may be used. The base  18  has a upper surface  22  and a bottom surface  24 . The main body  16  mates with the top surface  22  of the base  18  via a defined concave radius R. In an assembled state, both the upper surface  22  and the bottom surface  24  contact the cage  14  as shown in FIG. 2.  
         [0018]    With reference now to FIGS. 3 a  and  3   b , the through bore  20  is shown in greater detail. It will be understood that the through bore  20  described herein is adaptable to any type of fastener, and thus the principles disclosed herein are merely exemplary in nature. The through bore  20  can be characterized by three sections: a top countersink  26 , a middle threaded section  28  and bottom countersink  30 . The top countersink  26  ensures the bottom of the fastener does not extend beyond the main body  16 . The middle threaded section  28  has threads as dictated by the particular fastener employed. The bottom countersink  30  facilitates the alignment of a fastener therethrough and further assists in the subsequent alignment of the joining surfaces (FIG. 6). The bottom countersink  30  is proportionally larger than the top countersink  26  and may be defined by either an angled surface  32   a  as shown in FIG. 3 a  or a radius  32   b  as shown in FIG. 3 b.    
         [0019]    As best shown in FIG. 1, the cage  14  includes a body  34  with two flanges  36  and an upper surface  38 . The body  34  defines a central aperture  40 . The aperture  40  has a slightly larger diameter than the diameter of the bottom countersink  30  of the nut  12  to facilitate the receipt of a fastener therein. The body  34  further includes a pair of attachment points  42  which, in this embodiment, have an identical configuration. The configuration of the attachment points  42  can be adapted to suit the workpiece, as will be shown in the second embodiment. The attachment points  42  enable the cage nut fastener  10  to be affixed to a workpiece via any suitable means, such as, for example, welding, bolting, adhesion or riveting.  
         [0020]    The flanges  36  of the cage  14  serve to retain the nut  12 . The flanges  36  have cutouts  44  which correspond generally to the shape of the main body  16  of the nut  12 . The cutouts  44  are sized to restrict the movement of the nut  16  therein. In particular, as best shown in FIGS. 3 a  and  3   b , the cutouts  44  permit the nut  12  to move slightly away from the upper surface  38  of the cage  14  and also enable slight planar movement of the nut  12  generally parallel to the upper surface  38 .  
         [0021]    With reference now to FIG. 2, the cage nut fastener  10  is shown assembled. In order to assemble the nut  12  with the cage  14 , the through bore  20  of the nut  12  is co-axially aligned with the aperture  40  of the cage  14 . Next, the flanges  36  of the cage  14  are folded over the upper surface  38  of the base  18  of the nut  12 .  
         [0022]    A second alternate embodiment of the cage nut fastener  10  is shown in FIGS.  4 - 6 , wherein common reference numbers are utilized herein. The alternative embodiment is based on the previous embodiment, including a nut  12  and a cage  14 . Similar to the embodiments disclosed in FIGS.  1 - 3   b  the nut  12  and the cage  14  are configured to span a large gap or hole  103  formed in an automotive component, which will be described in detail below.  
         [0023]    In the alternative embodiment, the single piece nut  12  includes a main body  100 , a base  102  and a through bore  104  extending through both the main body  100  and the base  102 . Coupling the main body  100  and base  102  is a transition portion  101 . The main body  100  generally extends 10.7 mm to 12.6 mm above the base  102  with an outer diameter of 21.4 mm to 24.0 mm. The main body  100  is generally cylindrical, with an upper surface  106 . The upper surface  106  may optionally include a plurality of triangular grooves  108  as shown by phantom lines. These triangular grooves  108  provide a coefficient of friction to ensure that the nut  12  is properly torqued.  
         [0024]    The base  102  is generally oval in shape, however any shape suitable for the desired application would be within the scope of the present invention. The base  102  is has a width W of 35.1 mm to 39.7 mm and a length L of 43.2 mm to 48.3 mm. The base  102  has a top surface  110  and a bottom surface  112 . The main body  100  mates with the top surface  110  of the base  102  via a defined concave radius R at the transition portion  101 . Both the top surface  110  and the bottom surface  112  contact the cage  14  as shown in FIG. 5.  
         [0025]    As shown in FIG. 6, the through bore  104  can be characterized by three sections: a top countersink  114 , a middle threaded section  116  and a bottom countersink  118 . The top countersink  114  has a diameter between 13.5 mm to 14.9 mm. The top countersink ensures the bottom of the fastener does not extend beyond the upper surface  106  of the main body  100 . The middle threaded section  116  has threads as dictated by the particular fastener employed. Specifically, the number of threads and size of the threads is a function of the proof load required to meet a particular fastener class e.g. a Class 10 fastener.  
         [0026]    The bottom countersink  118  has a diameter which is preferably equal to diameter of the hole  103  formed in the component. The bottom countersink  118  has a diameter between 23.47 mm to 26.67 mm at an angle ranging between about 90 degrees and about 125 degrees. The specific angle of the countersink is a function of the diameter of the hole  103  in the component and the diameter of the threaded through bore  104 . The bottom countersink  118  which can be flat, concave or convex, facilitates the alignment of a fastener therethrough and further assists in the subsequent alignment of the joining surfaces (shown in FIG. 6).  
         [0027]    The main body  100  has a minimum wall thickness T 1  can be held constant throughout the length of the main body  100 . The base  102 , which is generally planar, has a minimum wall thickness T 2  that can be held constant throughout the length of the base  102 . The transition portion  103  has a minimum wall thickness T 3  can be held constant throughout the length of the transition portion  103 . The minimum thickness T 3  of the transition portion  103  can be greater than or equal to the minimum thickness T 1  of the body  100  or can be greater than or equal to the minimum thickness T 2  of the base  102 . Preferably, the minimum thickness T 3  of the transition portion  103  is greater than or equal to both the minimum thickness T 1  of the body  100  and is greater than or equal to the minimum thickness T 2  of the base  102 . Optionally, the wall minimum thickness T 1  of the body, the base T 2  and the transition portion T 3  are substantially constant throughout.  
         [0028]    With reference now to FIG. 4, the cage  14  has a body  120  defining a central aperture  122  and a pair of flanges  124 . The aperture  122  has a slightly larger diameter than the diameter of the bottom countersink  118  of the nut  12  to facilitate the receipt of a fastener therein. The body  120  has an upper surface  126  which contacts the nut  12 . The body  120  is further characterized by a first attachment point  128  and a second attachment point  130 . The first attachment point  128  is triangular in shape, while the second attachment point  130  is defined by three curved cutouts  132 . Both the first and second attachment points  128 ,  130  can be configured to mate with the workpiece (FIG. 6), and may be adapted for any type of suitable fastening means, such as, for example, welding, adhesion, bolting or riveting.  
         [0029]    The pair of flanges  124  each have a cutout  134  which enable the flanges  124  to mate substantially with the main body  100  of the nut  12 . The flange cutouts  134  retain the nut  12  in the cage  14  and are sized to restrict the movement of the nut  12  within the cage  14 . In particular, as best shown in FIG. 5, the cutouts  134  permit the nut  12  to move slightly away from the upper surface  126  of the cage  14  and also enable slight planar movement of the nut  12  generally parallel to the upper surface  126 . The movement of the nut  12  within the cage  14  provides for easier alignment of the nut  12  with a fastener (FIG. 6).  
         [0030]    With reference now to FIG. 5, the cage nut fastener  10  is shown assembled. In order to assemble the nut  12  with the cage  14 , the through bore  104  of the nut  12  is co-axially aligned with the aperture  122  of the cage  14 . Next, the flanges  124  of the cage  14  are folded over the upper surface  126  of the base  102  of the nut  12 .  
         [0031]    The nut  12  as described in either the first or second embodiment is a Class 10 or higher fastener. In this regard, a nut class is defined by its proof load in mega-Pascal (MPa) divided by 10. The shape of the main body  16 ,  100 , either conical or cylindrical, in conjunction with the transition portion, aids in reducing the weight of the nut  12  without significantly reducing the overall class or bearing strength of the nut  12 . The nut  12  may be formed by either cold or hot forming processes and is preferably manufactured from medium carbon steels (1022-1050), but may also be produced from low carbon steels (1008-1010). The nut  12  can also be optionally heat treated.  
         [0032]    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. For example, while a separate specific cage is shown, it is envisioned that a suitable structure, such as an inverted cage can be used. Additionally, the any structure which limits the range of movement of the nut with respect to a large gap or hole defined in the structure is envisioned. This specifically includes structures defined by or on the surface of the component the nut is coupled to. Such variations are not to be regarded as a departure from the spirit and scope of the invention.