Abstract:
An apparatus, system and method for releasably retaining a helical compression spring with respect to a threaded fastener. The threaded fastener includes an annular ridge that is sized and configured to retain the helical compression spring without interfering with the operation of the helical compression spring.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of the earlier filing date of U.S. Provisional Application No. 60/427,406, filed 19 Nov. 2002, which is incorporated by reference herein in its entirety. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    According to the present invention, a coil spring is retained on a cylindrical element during an assembly process in which the position or orientation of the cylindrical element is changed. For example, a retainer according to the present invention may be used in automotive assemblies, such as electric exhaust gas recirculation valves or other components, which require pre-assembly of a coil spring and another element into a sub-assembly that is used in a subsequent assembly operation.  
         BACKGROUND OF THE INVENTION  
         [0003]    A known electric exhaust gas recirculation valve, which may be used in automotive engine combustion emission control systems, includes a coil spring and a calibration bolt that bias an armature while allowing movement of the armature.  
           [0004]    In this known design, the coil spring is placed over the calibration bolt, and the calibration bolt is adjusted. In an automated assembly process, the calibration bolt could be inverted such that the coil spring would be prone to fall off the calibration bolt.  
           [0005]    Thus, it would be advantageous to provide an apparatus, system and method to retain the coil spring with respect to the calibration bolt.  
         SUMMARY OF THE INVENTION  
         [0006]    The present invention provides a retaining system that includes first and second elements. The first element includes a body that extends along a longitudinal axis between first and second end portions. The body has at the first end portion a first maximum outside dimension measured perpendicular to the longitudinal axis, and has at the second end portion a second maximum outside dimension measured perpendicular to the longitudinal axis. The second maximum outside dimension is greater than the first maximum outside dimension. The body also includes a band that generally surrounds the longitudinal axis at an intermediate portion between the first and second end portions. The band has a first lateral surface that generally faces the first end portion, a second lateral surface that generally faces the second end portion, and a crest between the first and second lateral surfaces. The crest defines a third maximum outside dimension that is greater than the first maximum outside dimension and that is less than the second maximum outside dimension. The second element is adapted to extend along the longitudinal axis and to surround the body. The second element includes a first section that is proximate the first end portion, a second section that is adapted to abut the second end portion, and an intermediate section that extends between and resiliently couples the first and second sections. The intermediate section is adapted to overly the band only at one position.  
           [0007]    The present invention also provides a retainer for loosely holding along a longitudinal axis a helical compression spring with respect to a threaded fastener. The helical compression spring includes generally closed first and second ends that are generally parallel to one another, and includes at least a portion of a coil that has a pitch measured along the longitudinal axis. The coil couples together the first and second ends. And the first end has an inside diameter. The threaded fastener includes a threaded section, a head, and a shank that couples the threaded section and the head. The threaded section and the shank have outside diameters that are less than the inside diameter of the first end. The retainer includes an annular ridge that projects from the shank. The annular ridge includes a first lateral surface that generally confronts the head, a second lateral surface that generally faces the threaded section, and a crest that is spaced along the longitudinal axis between the first and second lateral surfaces. The crest defines a maximum ridge diameter and is greater than the inside diameter of the first end of the helical compression spring.  
           [0008]    The present invention also provides a method of releasably retaining along a longitudinal axis a helical compression spring with respect to a threaded fastener. The helical compression spring includes generally closed first and second ends that are generally parallel to one another and includes at least a portion of a coil that has a pitch along the longitudinal axis. The coil couples the first and second ends, and the first end has an inside diameter. The threaded fastener includes a threaded section, a head, a shank that couples the threaded section and the head, and an annular ridge that projects from shank. The threaded section and the shank have outside diameters that are less than the inside diameter. The annular ridge includes a first lateral surface that generally confronts the head, a second lateral surface that generally faces the threaded section, and a crest that is spaced along the longitudinal axis between the first and second lateral surfaces. The crest defines a maximum ridge diameter that is greater than the inside diameter of the first end of the helical compression spring. The method includes moving, substantially without interference, away from the threaded section, the first end over the first lateral surface; snapping the first end over the crest; and moving, substantially without interference, toward the head, the first end over the second lateral surface and a portion of the shank. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate presently preferred embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain features of the invention.  
         [0010]    [0010]FIG. 1 is plan view of a threaded fastener including a retainer in accordance with the detailed description of a preferred embodiment.  
         [0011]    [0011]FIG. 2 is a cross-section showing a helical compression spring that may be used with the threaded fastener shown in FIG. 1.  
         [0012]    [0012]FIG. 3 is a schematic illustration showing a relative position of the threaded fastener shown in FIG. 1 and the helical compression spring shown in FIG. 2, before the helical compression spring is retained with respect to the threaded fastener.  
         [0013]    [0013]FIG. 4 is a schematic illustration showing a relative position of the threaded fastener shown in FIG. 1 and the helical compression spring shown in FIG. 2, as the helical compression spring is being retained or released with respect to the threaded fastener.  
         [0014]    [0014]FIG. 5 is a schematic illustration showing a relative position of the threaded fastener shown in FIG. 1 and the helical compression spring shown in FIG. 2, after the helical compression spring is retained with respect to the threaded fastener. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]    [0015]FIG. 1 shows a threaded fastener  100 , which can be a screw, bolt, or another type of fastener. The threaded fastener  100  includes a body  102  that extends along a longitudinal axis L between a first end portion  110  and a second end portion  120 . According to a preferred embodiment, the first end portion  110  includes at least one thread  112 , and the second end portion  120  includes a head  122 . The first end portion  110  has a maximum outside dimension OD 1 , and the second end portion  120  has a maximum outside dimension OD 2 . According to the preferred embodiment, the maximum outside dimension OD 1  represents the diameter of the at least one thread  112 , and the maximum outside dimension OD 2  represents the size of the head  122 . The maximum outside dimension OD 2  exceeds the maximum outside dimension OD 1 .  
         [0016]    Extending between and coupling the first and second end portions  110 , 120  is an intermediate portion  130 . According to the preferred embodiment, the intermediate portion  130  includes a shank  132 , or unthreaded portion, and the maximum outside dimension OD 1  represents the diameter of the shank  132 .  
         [0017]    Extending from the intermediate portion  130  is an annular band  140  that a maximum outside dimension OD 3 . The maximum outside dimension OD 3  exceeds the maximum outside dimension OD 1 , but is less than the maximum outside dimension OD 2 . According to a preferred embodiment, the band  140  includes a first lateral face  142  that generally faces the first end portion  110 , and includes a second lateral face  144  that generally facing the second end portion  120 . Further, according to the preferred embodiment, the first and second lateral faces  142 , 144  each include respective sloping sections that intersect at a crest  146 , which defines the maximum outside dimension OD 3 . According to a most preferred embodiment, when viewed in a cross-section including the longitudinal axis L, the -first and second lateral faces  142 , 144 , including their respective sloping sections, define a semi-circle with the crest  146  at the apex of the semi-circle.  
         [0018]    [0018]FIG. 2 shows a helical compression spring  200  that may be used, according to the present invention, with the threaded fastener  100 . The helical compression spring  200  extends along a longitudinal axis L between a first section  210  and a second section  220 . According to a preferred embodiment, the first section  210  includes a first generally closed end  212 , and the second section  220  includes a second generally closed end  222 . As it is used in this description, the phrase “closed end” refers to a nearly circular loop that lies in an imaginary plane that is substantially orthogonal with respect to the longitudinal axis L. According to a preferred embodiment, the first and second generally closed ends  212 , 222  have a common minimum inside dimension ID. However, the first and second generally closed ends  212 , 222  can have different minimum inside dimensions so long as both are larger than the maximum outside dimension OD 1 , and the minimum inside dimension of the second generally closed end  222  is less than maximum outside dimension OD 2 . In practice, the minimum inside dimension ID and the maximum outside dimension OD 3  are cooperatively selected such that there is some interference therebetween, while minimizing the force necessary to push the minimum inside dimension ID through the maximum outside dimension OD 3 .  
         [0019]    Extending between and coupling the first and second sections  210 , 220  is an intermediate section  230 . According to the preferred embodiment, the intermediate section  230  includes a body  232  having the form of at least a portion of a resilient coil that has a pitch. As it is used in this description, the term “pitch” refers to a count of the number of twists the body  232  makes around longitudinal axis L per unit length of the longitudinal axis L and, in conjunction with the size of the material for the body  232 , relates to the spacing along the longitudinal axis L of adjacent twists in the intermediate section  230 . According to a preferred embodiment, the intermediate section  230  includes a plurality of twists of the body  232 , and has a minimum inside dimension at least as great as the minimum inside dimension ID.  
         [0020]    Referring now to FIGS.  3 - 5 , and initially to FIG. 3, the threaded fastener  100  and the helical compression spring  200  are aligned along the longitudinal axis L, and the helical compression spring  200  is displaced along the longitudinal axis L, substantially without interference, so as to surround the first end portion  110 . As it is used in this description, the phrase “substantially without interference” refers to relative movement that is not opposed by sliding friction. For example, relative movement substantially without interference would, in the case of relative movement along the longitudinal axis L between the threaded fastener  100  and the helical compression spring  200 , occur when there is no engagement or minimal contact between the minimum inside dimension ID and the maximum outside dimension OD 3 .  
         [0021]    As shown in FIG. 4, as the helical compression spring  200  continues to be displaced along the longitudinal axis L, the first generally closed end  212  engages the band  140  on the intermediate portion  130  of the threaded fastener  100 . In particular, the first generally closed end  212  initially engages the sloping section of the first lateral surface  142 , and is resiliently expanded as it approaches the crest  146 . At the instant that the first generally closed end  212  and the crest  146  are commonly located along the longitudinal axis L, the minimum inside dimension ID of the first generally closed end  212  is approximately the same size as the maximum outside dimension OD 3 .  
         [0022]    Referring now to FIG. 5, as the helical compression spring  200  continues to be displaced along the longitudinal axis L, substantially without interference, the first generally closed end  212  is loosely retained along the longitudinal axis L between the band  140  and the second end portion  120 . As it is used in this description, the term “loosely” refers to allowing appreciable movement. For example, loosely retained would, in the case of the first generally closed end  212 , allow appreciable movement along the longitudinal axis L between the band  140  and the second end portion. According to the preferred embodiment, the first generally closed end  212  resiliently contracts as it moves away from the crest  146  and subsequently disengages the sloping section of the second lateral surface  144 .  
         [0023]    By cooperatively selecting the pitch of the intermediate section  230  such that the spacing along the longitudinal axis L of adjacent twists in the intermediate section  232  is greater than the longitudinal width of the band  140  (measured along the longitudinal axis L between the first and second lateral surfaces  142 , 144 ), ensures that there is only one occurrence of the body  232  overlying the band  140 .  
         [0024]    In order to release the threaded fastener  100  with respect to the helical compression spring  200 , the sequence shown and described with respect to FIGS.  3 - 5  is reversed.  
         [0025]    Advantages of the present invention include that the operation of the helical compression spring  200  is unaffected when the helical compression spring  200  is retained on the threaded fastener  100 . It is believed that this is at least in part due to the body  232  overlying the band  140  only at one position. Another advantage of the present invention is that, due to the helical compression spring  200  and the threaded fastener  100  being relatively releasable, alternate ones of the helical compression spring  200  can be retained on a single threaded fastener  100 . Consequently, it is possible according to the present invention to replace a worn or fatigued helical compression spring with a fresh helical compression spring, and to substitute helical compression springs having different spring rates.  
         [0026]    While the present invention has been disclosed with reference to certain preferred embodiments, numerous modifications, alterations, and changes to the described embodiments are possible without departing from the sphere and scope of the present invention, as defined in the appended claims. Accordingly, it is intended that the present invention not be limited to the described embodiments, but that it have the full scope defined by the language of the following claims, and equivalents thereof.