Abstract:
An RTD connector seal to couple and seal an RTD device to an RTD cable. The RTD connector seal includes a tubular sleeve defining an groove in an interior surface proximate each end of the sleeve. The RTD connector seal includes a pair of end plugs, each end plug defining a first channel configured to receive an O-ring and a second channel configured to receive stacked O-rings, with one O-ring aligned with the groove in the sleeve, each end plug defining a through hole configured to receive one of the RTD device and RTD cable. The RTD connector seal includes a terminal plate coupled to each end plug and configured to slidingly engage the interior surface of the sleeve. The RTD connector seal includes a terminal block mounted on the terminal plate, wherein the RTD device is coupled to the RTD cable on the terminal block sealed within the sleeve.

Description:
FIELD OF INVENTION 
   The present invention relates generally to the field of resistance temperature detectors (RTDs), and more particularly to a fluidly sealed connector for a RTD device and RDT cable. 
   BACKGROUND OF THE INVENTION 
   RTDs are well known for measuring temperature based on their coefficients of resistivity. RTDs operate on the principle of changes in electrical resistance of pure metals and are characterized by a linear positive change in resistance with temperature. When heated, the resistance of the metal increases; when cooled, the resistance decreases. Passing current through an RTD generates a voltage across the RTD. By measuring this voltage, you determine its resistance, and thus its temperature. Typical elements used for RTDs include nickel (Ni) and copper (Cu), but platinum (Pt) is by far the most common because of its wide temperature range, accuracy, and stability. RTDs are popular because of their excellent stability, and exhibit the most linear signal with respect to temperature of any electronic temperature sensor. 
   RTDs are typically constructed by one of two different manufacturing configurations. Wire-wound RTDs are constructed by winding a thin wire into a coil. A more common configuration is the thin-film element, which consists of a very thin layer of metal laid out on a plastic or ceramic substrate. Thin-film elements are cheaper and more widely available because they can achieve higher nominal resistances with less platinum. To protect the RTD, a metal sheath encloses the RTD element and the lead wires connected to it. Such metal sheaths as are currently known in the art, however, when submerged in a fluid such as water for up to 24 hours, for example, are not capable providing an adequate seal around the element and wires without a leak. 
   Thus there is a need for an RTD connector seal to couple and seal an RTD element to an RTD cable so that the RTD connector seal is capable of remaining submerged in a medium for a period of time while obtaining temperature data. There is also a need for a method of connecting an RTD element to an RTD cable in an RTD junction box so that the RTD element, cable, and junction box are capable of remaining submerged in a medium for a period of time while obtaining temperature data. 
   SUMMARY OF THE INVENTION 
   One embodiment of the invention relates to an RTD connector seal to couple and seal an RTD device to an RTD cable. The RTD connector seal comprises a tubular sleeve defining an annular groove in an interior surface proximate each end of the sleeve. The RTD connector seal further comprises a pair of end plugs, each end plug defining a first annular channel configured to receive an O-ring and a second annular channel configured to receive stacked O-rings, with one O-ring aligned with the annular groove in the sleeve, each end plug further defining a through hole configured to receive one of the RTD device and RTD cable. The RTD connector seal further comprises a terminal plate coupled to each end plug and configured to slidingly engage the interior surface of the sleeve. The RTD connector seal further comprises a terminal block mounted on the terminal plate, wherein the RTD device is coupled to the RTD cable on the terminal block sealed within the sleeve. 
   Another embodiment of the invention relates to an apparatus to fluidly seal a terminal connection of an RTD device and an RTD cable. The apparatus comprises a tubular sleeve including an interior surface, the sleeve having a first end and a second end, and a groove defined in the interior surface proximate each of the first and second ends. The apparatus further comprises a first plug disposed in the first end and a second plug disposed in the second end, with each plug configured to support a plurality of seals, wherein at least one seal on each plug engages the groove at each respective end of the sleeve and at least one seal on each plug fluidly seals the plug against the interior surface of the sleeve. The apparatus further comprises a terminal member disposed inside the sleeve between and coupled to the first and second plug and in contact with the interior surface of the sleeve, with the terminal member configured to couple the RTD device and the RTD cable together, wherein the terminal member guides the sleeve as the sleeve moves to expose the terminal member. 
   Another embodiment of the invention relates to a method of connecting an RTD device to an RTD cable in a RTD junction box, the junction box including a slidable sleeve and a terminal member, for submersion in a fluid. The method comprises the step of coupling the RTD device to the junction box. The method further comprises the step of coupling the RTD cable to the junction box. The method further comprises the step of moving the slidable sleeve from a first position to a second position indexed by an O-ring inserting into an annular groove defined in an interior surface of the sleeve, wherein the terminal member is exposed. The method further comprises the step of attaching the RTD device and RTD cable to each other on the terminal member. The method further comprises the step of moving the slidable sleeve to the first position indexed by the O-ring inserting into another annular groove defined a spaced distance from the other annular groove in the interior surface of the sleeve, wherein at least two other O-rings fluidly seal the terminal member inside the sleeve 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a top partial cross-section of a resistance temperature detector and cable coupled in a junction box according one example embodiment. 
       FIG. 2  is top cross-section of the junction box of  FIG. 1  with the sleeve of the junction box in a closed position according to one example embodiment. 
       FIG. 3  is a side cross-section of the junction box of  FIG. 1  with the sleeve of the junction box in a closed position according to one example embodiment. 
       FIG. 4  is a top cross-section of the junction box of  FIG. 1  with the sleeve of the junction box in a an open position according to one example embodiment. 
       FIG. 5  is an end view cross-section of the junction box of  FIG. 1  along the line  5 - 5  according to one example embodiment. 
   

   DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     FIG. 1  illustrates one example of a resistance temperature detector (RTD)  10  configured to have wire connections substantially sealed from the environment around it in a junction box  16 , also referred to as a connector seal. RTD  10  includes stem  12 , cable  14 , and junction box  16 . Stem  12  is the portion of RTD  10  that retrieves temperature measurements. Stem  12  includes probe  18  and fitting  20 . Probe  18  is intended to provide fast responses of temperature changes. In the illustrated example embodiment, probe  18  is inserted into a subject of interest  21  in order to obtain temperature data from it. Probe  18  is retained within fitting  20  by an adhesive or fastening means. In one example embodiment, probe  18  may be retained within fitting  20  using glue. In other example embodiments, probe  18  may be retained by welding, soldering, or any other known means. In another example embodiment, probe  18  may be made of platinum, while in other example embodiments, probe  18  may be made of nickel, copper, or any other material suitable for retrieving temperature data. 
   Cable  14  is coupled to junction box  16  and stem  12  and both provides temperature data to a user interface, such as a central processing unit or the like, and provides power to stem  12 . In one embodiment, cable  14  may be coupled to junction box  16  via a wire connector fitting. In other example embodiments, cable  14  may be coupled to junction box  16  using any national pipe thread connection or any other suitable means that fluidly seals the junction box  16 . 
   Referring to  FIG. 2 , junction box  16  will be described in greater detail. Junction box  16  serves as a connector of stem  12  and cable  14  and well as a seal for enclosed wire terminals. The seal is intended to enable RTD  10  to remain within a medium, such as a fluid, with a reduced chance of the medium leaking into junction box  16 . Junction box  16  generally includes body  22  and sleeve  24 . Body  22  serves to physically and electrically couple stem  12  and cable  14  together. Body  22  includes terminal plate  28 , fasteners  30 , terminal block  32 , connectors  34 , and end plugs  36 . Plate  28  serves as a base for block  32  to be fastened via fasteners  30  and abuts against sleeve  24  (as described in greater detail below). 
   Block  32  serves as a contact point for stem  12  and cable  14  to be coupled together. Wires from stem  12  and cable  14  are connected together by insertion into block  32  and making contact with connectors  34 . In one example embodiment, block  32  may be made of a nylon material, while in other example embodiments, block  32  may be of any suitable materials that serves as an insulator or holds form in a wide temperature range. In another example embodiment, connectors  34  may be screws, while in other example embodiments, connectors  34  may be wire connectors or any other suitable fastening device. 
   End plugs  36  each define a through-hole  38 , a channel  40 , and a channel  42  and each include at least three O-rings  44 ,  46 , and  48 . Through-hole  38  receives and retains either stem  12  or cable  14  in a substantially sealed fashion. Channel  40  is configured to retain O-ring  44 , which makes contact with sleeve  24  in order to maintain positioning of and to aid in substantially sealing sleeve  24 . Channel  42  is configured to retain stacked O-rings  46  and  48 . O-ring  46  is positioned as an internal O-ring while O-ring  48  is positioned in an external fashion around O-ring  46 . O-ring  46  acts to bias O-ring  48  against sleeve  24  in order to form a substantial seal and to index the position of sleeve  24  as described below. 
   Sleeve  24  is a cylindrical section of material that is configured to substantially seal junction box  16  from an outside medium by compressing O-rings  44 ,  46 , and  48 . Sleeve  24  is configured to reciprocally slide between a first and second position. In on example embodiment, each of the first and second positions may correspond to an open position, where the wire connections to block  32  may be maintained, or a closed position, which is intended to substantially seal the wire connections. In another example embodiment, each of sleeve  24 , plate  28 , fasteners  30 , connectors  34 , end plugs  36  may be constructed of stainless steel. In other example embodiments, each of these components of junction box  16  may be made of any other metal or polymer material or combination thereof that is suitable for the tasks each component is intended to perform. 
     FIG. 3  illustrates a side view of junction box  16  and how the wires from stem  12  and cable  14  connect to block  32 . Block  32  defines holes  50  that are configured to receive wires from each of stem  12  and cable  14  for connection via connectors  34 . In the illustrated example embodiment, block  32  is fastened to plate  28  via fasteners  30 , shown as bolts, which pass through plate  28 . In another example embodiment, fasteners  30  may be screws, while in other embodiments fasteners  30  may be any other suitable fastening means such clips, adhesive, or the like. 
     FIG. 4  illustrates junction box  16  with sleeve  24  in the open position where the wire connections from stem  12  and cable  14  may be maintained. Each end of sleeve  24  defines a groove  54 . These grooves receive O-rings  48 . When sleeve  24  is in the open position, groove  54  receives O-Ring  48  in order to index and retain sleeve  24  in this open position. When sleeve  24  is in the closed position, O-ring  44  is compressed by the interior surface  56  of sleeve  24  and forms a seal  7  and groove  54  receives O-ring  48 , which indexes the position of sleeve  24  and forms a substantial seal with interior surface  56  of sleeve  24  due to the compression created from the bias of O-ring  46 . 
     FIG. 5  illustrates an cross-sectional end view of junction box  16  and how plate  28 , fasteners  30 , and block  32  are aligned within, sleeve  24 . Plate  28  is configured to be tangential to sleeve  24 . This abutment of plate  28  to sleeve  24  serves as a guide for sliding sleeve  24  between the open and closed positions. While the illustrated example embodiment shows that sleeve  24  is a cylindrical shape, in other embodiments, sleeve  24  may be prismatic, pyramidal, or any other suitable shape. Likewise, while plate  28 , fastener  30 , and block  32  are shown to have a specific shape in the illustrated embodiment, in other example embodiments, the RTD seal elements may be of any shape that facilitates the intended functionality. The plate  28  and block  32  may also be a single integral member fabricated by any suitable method such as injection molding. 
   For purposes of this disclosure, the term “coupled” means the joining of two components (electrical or mechanical) directly or indirectly to one another. Such joining may be stationary in nature or movable in nature. Such joining may be achieved with the two components (electrical or mechanical) and any additional intermediate members being integrally defined as a single unitary body with one another or with the two components or the two components and any additional member being attached to one another. Such joining may be permanent in nature or alternatively may be removable or releasable in nature. Further, for purposes of this disclosure, the term “seal” means to prevent entry of a fluid into junction box  16  for a selected period of time. 
   The present disclosure has been described with reference to example embodiments, however workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the claimed subject matter. For example, although different example embodiments may have been described as including one or more features providing one or more benefits, it is contemplated that the described features may be interchanged with one another or alternatively be combined with one another in the described example embodiments or in other alternative embodiments. Because the technology of the present disclosure is relatively complex, not all changes in the technology are foreseeable. The present disclosure described with reference to the example embodiments and set forth in the following claims is manifestly intended to be as broad as possible. For example, unless specifically otherwise noted, the claims reciting a single particular element also encompass a plurality of such particular elements. 
   It is also important to note that the construction and arrangement of the elements of the system as shown in the preferred and other exemplary embodiments is illustrative only. Although only a certain number of embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited. For example, elements shown as integrally formed may be constructed of multiple parts or elements shown as multiple parts may be integrally formed, the operation of the assemblies may be reversed or otherwise varied, the length or width of the structures and/or members or connectors or other elements of the system may be varied, the nature or number of adjustment or attachment positions provided between the elements may be varied. It should be noted that the elements and/or assemblies of the system may be constructed from any of a wide variety of materials that provide sufficient strength or durability. Accordingly, all such modifications are intended to be included within the scope of the present disclosure. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the preferred and other exemplary embodiments without departing from the spirit of the present subject matter.