Abstract:
A strain relief device includes an elongated body having a first and second end, the elongated body defining an elongated hole extending from the first end to the second end; and edges in the body defining a plurality of voids between the first and second end, wherein the edges become shorter in length from the first end to the second end such that the shorter edges define progressively smaller voids in the body from the first end to the second end. A method of providing a strain relief is also disclosed.

Description:
TECHNICAL FIELD 
       [0001]    This patent disclosure relates generally to a strain relief device and, more particularly, to a strain relief device for a harness. 
       BACKGROUND 
       [0002]    Conduits, cables, and harness assemblies often include a cable or other conduit that fits into a relatively rigid portion. The cable or conduit may be subject to flexing over the course of its use. This flexing may result in concentrated stress or strain at the point of where the conduit for cable attaches to the more rigid structure. Over time, this increased stress and strain can result in the conduit and/or protective isolative covering over the conduit cracking, breaking, or otherwise failing. 
         [0003]    Strain relief devices have been used at the connection between the conduit or cable and the more rigid structure in order to reinforce the conduit or cable at the point of connection to the more rigid structure. However, some strain relief devices suffer from various drawbacks. For example, some strain relief devices transfer concentrated stress from a point where the cable conduit enters more rigid structures to the point where the conduit or cable contacts the strain relief device. Other strain relief devices cannot withstand high temperatures and/or are not able to bend at extreme angles. Other strain relief devices suffer from various other drawbacks. 
         [0004]    WO 2007/113307 titled “RETENTION FERRULE FOR CABLE CONNECTOR” describes an apparatus that is of a similar construction along its axial length. As a result, it is assumed that it maintains a similar stiffness along its length, which may, in some instances, result in directing strain towards a point where the strain relief device and conduit or cable meet. Accordingly, there is a need for an improved strain relief device. 
       SUMMARY 
       [0005]    In one aspect, the disclosure describes a strain relief device that include an elongated body having a first and second end, the elongated body defining an elongated hole extending from the first end to the second end; and edges in the body defining a plurality of voids between the first and second end, wherein the edges become shorter in length from the first end to the second end such that the shorter edges define progressively smaller voids in the body from the first end to the second end. 
         [0006]    In another aspect, the disclosure describes a method of providing a strain relief device. The method includes forming a strain relief device body having two ends; forming an elongated hole in the strain relief device body connecting the first end to the second end; providing edges defining voids in the conduit; and dimensioning the edges to be shorter from the first end of the body to the second end of the body such that the voids defined by the edges become progressively smaller from the first end of the body to the second end. 
         [0007]    In yet another aspect, the disclosure describes a strain relief device that includes an elongated body made of a silicone material, the body having a first and second end, the elongated body defining an elongated hole extending from the first end to the second end, wherein the body has two clamshell sections, each clamshell section having a first and second end which correspond to the first and second ends of the body, and edges in each of the clamshell sections defining a plurality of voids between the first and second ends, wherein the edges become shorter in length from the first end to the second end such that the shorter edges define progressively smaller voids in the clamshells from the first end to the second end. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a perspective view of a strain relief device assembly attached to a sensor. 
           [0009]      FIG. 2  is a perspective view of a clamshell comprising part of the strain relief device. 
           [0010]      FIG. 3  is a perspective, exploded end view of two clamshells which form the strain relief device. 
           [0011]      FIG. 4  is an exploded, perspective, side view of two clamshells which foam the strain relief device. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    Now with reference to the drawings, like reference numbers refer to like elements,  FIG. 1  is a perspective view of a strain relief device  10  that is installed about a cable  12  which may be connected to a sensor  14 . The sensor  14  may be a NOx sensor, a pressure sensor, a temperature sensor, or any other type sensor. In other aspects, the strain relief device  10  may be used on a cable or cord that is not associated with a sensor all.  FIG. 1  shows an area  13  where the cable  12  connects to the strain relief device  10 . The sensor  14  also has an attaching nut  16  which allows the sensor  14  to be twisted. Typically, twisting is desired to install the sensor  14  via threads (not shown). 
         [0013]      FIG. 2  is a perspective view of a portion of the strain relief device  10 . The strain relief device  10  may be comprised of a first clamshell  18  and a second clamshell  20 . (See, for example,  FIGS. 3 and 4 ).  FIG. 2  illustrates the first clamshell  18 . In some aspects the second clamshell  20  is structurally the same as, or similar to, the first clamshell  18 . As result, one of ordinary skill in the art after reviewing this disclosure will understand features associated with a second clamshell  20  without a separate description of it beyond what is described with respect the first clamshell  18 . 
         [0014]    The first clamshell  18  has a first end  22  and a second end  24 . In some aspects, the clamshell  18  has a generally tapered shape  26  so that when the first clamshell  18  and second clamshell  20  are assembled as shown in  FIG. 1 , the strain relief device  10  has a cross-sectional diameter that is larger at the first end  22  and gradually gets smaller so that the cross-sectional diameter of the strain relief device  10  at the second end  24  is smaller than the cross-sectional diameter of the first end  22 . 
         [0015]    The first clamshell  18  includes a body  28 . In some aspects the body  28  is comprised of a silicone material. For example, in some aspects, the body  28  is composed of a fluro-silicone material that may be commercially available. In some aspects, the body  28  is made of a silicone material that has a durometer of at least 80 shore A. Furthermore, the material comprising the body  28  may be resilient and is biased to return to an initial shape when the material is flexed and deformed to a shaped different than that of the initial shape. The initial shape may be any initial shape desired. However in some aspects, the initial shape is a straight, elongated shape. An example of a straight, elongated shape is shown in  FIGS. 1 through 4 . In some instances, during use the strain relief device  10 , the strain relief device  10 , may be bent at extreme angles including or exceeding a 90° bend. 
         [0016]    In some aspects, the initial shape may be at an elongated shape at least four times longer than the cross-sectional diameter at the first end  22 . The longer the length of the strain relief device  10 , the more the strain relieve device  10  can spread strain over a longer area. As a result, a longer strain relief device  10  may provide better performance than a shorter one. 
         [0017]    The material comprising the body  28  may be selected so that the strain relief device  10  may be bent up to and perhaps exceeding a 90° bend but will still be biased to return to its initial shape once the forces causing the strain relief device to bend are removed. Furthermore, the material may be selected so that the strain relief device  10  may be subjected to temperatures up to, and in some instances exceeding, 200° C. The materials selected may withstand temperatures up to, and including, 200° C. without causing melting, deformation, or otherwise degradation of the strain relief device  10 . Furthermore, in some aspects, the material selected may be able to withstand multiple cycles of temperatures moving up to 200° C. and cooling back down again as well as being bent at extreme angles without degrading the material or causing the material to no longer be biased to return to its initial shape. As mentioned above, the material may be a silicone material and/or fluro-silicone. 
         [0018]    As shown in  FIG. 2 , the first clamshell  18  includes edges  29  which define voids or holes  30 . The body  28  is present between the holes or voids  30 . In some aspects, the holes or voids  30  are smaller near the first end  22  and grow larger toward the second end  24  of the clamshell  18 . The holes  30  can grow successively larger along the length of axis A-A from the first end  22  to the second end  24 . Alternatively, holes  30  of similar size may be grouped together and the various groups may have different sized holes  30  within the groups and the size of the holes  30  growing larger along axis A-A from the first end  22  to the second end  24 . In addition, the edges  29  may be shorter or smaller towards the first end  22  and grow larger and thus, define larger holes or voids  30  toward the second end  24 . The change in shape and size of the holes or voids  30  along the length of the strain relief device  10 , results in the strain relief device  10  having a different stiffness along the axis A-A or, in other words, a difference in stiffness along the axial length of the strain relief device  10 . Having a different stiffness along the length of the strain relief device  10 , results in stress and/or strain being spread along the length of the strain relief device. Having a different stiffness can also reduce the likelihood of the strain relief device concentrating stress at an area  13  where the conduit  12  and strain relief device  10  meet. 
         [0019]    As a corollary to the holes  30  becoming larger from the first end  22  to the second end  24 , the body sections  32  between the holes  30  becomes smaller from the first end  22  to the second end  24 . Because these sections  32  becomes smaller, the strain relief device  10  becomes less rigid toward the second end  24  compared to the first end  22 . What can further contribute to the change in rigidity along the length of the strain relief device is the fact that the strain relief device  10  is tapered  26 . Thus, the reduction in rigidity at the second end  24 , may be attributed to reduced material present in the strain relief device  10  resulting from the strain relief device  10  being smaller due to the tapered shape  26 , and the reduction of material present in the strain relief device  10  due to the reduction in size of the body sections  32  between the increasing in sized voids  30 . The holes  30  may be oriented to have an axis B-B that intersects axis A-A at a right angle. 
         [0020]      FIG. 3  is an end view of a strain relief device  10  comprising the first clamshell  18  located over the second clamshell  20 . The arrows C illustrate how the clamshells  18  and  20  fit together to form the strain relief device  10 .  FIG. 3  illustrates that the strain relief device  10  has, when assembled, a cross-section generally in the shape of an annulus. 
         [0021]      FIG. 4  is a perspective view of the first clam shell  18  and the second clamshell  20  located beneath the first clamshell  18 . Again the arrows C illustrate how the clamshells  18  and  20  can come together. The voids or holes  30  are illustrated as increasing in size moving along axis A-A from the first end  22  to the second end  24 . 
         [0022]    As shown in  FIGS. 2 and 4 , The ridges  36  define solid sections  34  where there are no holes or voids  30  in the flat sections  38  between the ridges  36 . Sets of ridges  36  can be found near the first end  22  and the second end  24 . In some aspects, the flat sections  38  between the ridges  36  may be used as a location for a connecting band or other mechanical fastener for connecting the first clamshell  18  to the second clamshell  20 . 
         [0023]    In some aspects, the strain relief device  10  may include a solid middle section  40  in which no holes or voids  30  are present. In some aspects, the solid middle section  40  may also be used as a place to locate a mechanical fastener for connecting the first clamshell  18  to the second clamshell  20 . 
         [0024]    In some aspects, and as shown in the figures, both clamshells  18  and  20  may include seam regions  42  which are located along axis A-A. No voids or holes  30  are located in the seam regions  42 . In other aspects, holes or voids  30  may be present in the seam regions  42 . The seam regions  42  may define a contacting surface  44  where the first clamshell  18  and the second clamshell  20  contact each other when the strain relief device  10  is assembled. 
       INDUSTRIAL APPLICABILITY 
       [0025]    The strain relief device  10 , as described herein, may be used as a protective apparatus to be fit over cables, conduits, or any other elongated flexible connector. The strain relief device  10  may help protect a cable or conduit from stress and strain which can cause cracking or any other undesirable degradation in performance for the conduit, cable, or other flexible connector. Some advantages found in the strain relief device  10 , described herein, are that it is able to withstand high temperatures without degradation of its performance In addition, the strain relief device  10 , described herein, may be bent at extreme angles and spread stress over the length of the strain relief device  10 . By having a different stiffness along the strain relief device  10 , the strain relief device  10  can diffuse stress along the length and reduces the likelihood of concentrating stress on the cable, conduit, or other flexible connector. 
         [0026]    One of ordinary skill in the art after reviewing this disclosure will be able to manipulate the design and/or material used in the strain relief device  10  to achieve a desired stiffness in the strain relief device  10 . For example, the size and location of the holes  30 , the amount of taper, and the material used to make the strain relief device  10  can be adjusted to achieve a strain relief device  10  having desired characteristics for a particular application. 
         [0027]    It will be appreciated that using larger holes  30  and/or locating the holes  30  close together along one portion of the strain relief device  10  will result in that portion of the strain relief device  10  being less rigid. This is due to the fact that larger holes  30  and/or the holes  30  being spaced closely together results in less material being present in that portion of the strain relief device  10 . With less material being present in that portion, that portion will become less rigid. 
         [0028]    Conversely, reducing the size of the holes  30  and/or spacing the holes  30  farther apart along a portion of the strain relief device  10  will result in that portion of the strain relief device  10  being more rigid. This is due to the fact that by making the holes  30  smaller and/or spacing the holes  30  apart, more material will be present along that portion of the strain relief device  10 . With that portion having more material, then that portion will become more rigid. 
         [0029]    It should also be appreciated that tapering the outer diameter of the strain relief device  10  will results in greater material present at the larger end of the strain relief device and less material being present at the tapered end. With less material being present along the length of the strain relief device  10  as result of the taper, the rigidity or stiffness of the strain relief device  10  will vary from more rigid at the non-tapered to less rigid toward the tapered end. 
         [0030]    Additional advantages may be found in that even when the strain relief device  10  described herein is bent at extreme angles, the strain relief device  10  will still be biased to return to its original configuration. In addition, in some aspects, even if the strain relief device  10  is subject to several cycles of intense heat while bent at an extreme angle, the strain relief device  10  will not be thermally set to a new position but rather will still be biased to return to its original configuration. 
         [0031]    It will be appreciated that the foregoing description provides examples of the disclosed device and technique. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated. 
         [0032]    Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. 
         [0033]    The many features and advantages of the disclosure are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the disclosure which fall within the true spirit and scope of the disclosure. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the disclosure to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the disclosure.