Abstract:
The present invention is a leak detection mechanism for use with a pressurized system and relates generally to an assembly for connecting a conduit to a component. The mechanism utilizes a fluid passageway for detecting a leak or absence of a seal after connecting a conduit to a component such as an expansion valve of a pressurized fluid system. The fluid passageway forms a predetermined leak path enabling fluid flow into or out of the system when an o-ring or other seal means is missing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to an assembly for connecting conduit to a component. More specifically, this invention relates to a mechanism for detecting a leak or absence of a seal after connecting a conduit to a component, such as connection block or an expansion valve, of a pressurized fluid system. 
         [0004]    2. Description of Related Art 
         [0005]    Modern automotive air-conditioning systems generally include a compressor, condenser, evaporator, expansion valve and a plurality of conduits or lines that connect the various components. A suitable refrigerant is contained within the system. Installation of the various air-conditioning system components is typically independent of one another with the conduit connected to the components after they are installed or mounted to the vehicle. While different methods and apparatuses for securing the conduit to the various components are known, one method utilizes an o-ring encircling an end of conduit that provides a seal when the end of the conduit is secured in a port on the component. 
         [0006]    To secure the end of the conduit to the component, a connection plate engages and traps the conduit in a conduit passage extending through the plate. The connection plate further includes a second passageway offset from and parallel to the conduit passage. Once the conduit and is inserted into a port on the component, a fastener extending through the second passageway secures the connection plate to the component whereby the end of the conduit is connected to the component. 
         [0007]    Vehicle space limitations and packaging consideration sometimes make it difficult for an assembler to attach the conduit to the various components due to their location on the vehicle. In addition, mass production constraints, wherein the vehicles are traveling rapidly on an assembly, limit the time provided to connect the conduit to the various components. Thus, during or prior to the assembly process and unbeknownst to the assembler, the o-ring may be damaged or missing from the end of the conduit. Accordingly, the conduit may be installed to the component with a damaged o-ring or without the o-ring. 
         [0008]    To insure the system is properly assembled, the system undergoes a leak test prior to filling the system. The leak test typically involves the use of a vacuum leak testing system that draws a vacuum on the system and monitors the level and hold time of the vacuum. Accordingly, an air conditioning system may ultimately pass the leak test even though the o-ring is damaged or missing. For example, in some instances the connection plate provides sufficient pressure on an annular bead or upset portion of the conduit to compress it against the component thereby forming a temporary or limited seal. Such a seal results in a slow leak. The leak detection system may not detect such slow leaks resulting in the system passing the leak test and being filled with refrigerant. Over time, the refrigerant leaks out and the system ceases to work, resulting in warranty concerns along with expensive and time-consuming repairs. 
         [0009]    Accordingly, it is desirable to provide a conduit to component fitting assembly having a leak detection mechanism that cooperates with the leak detection system to detect a missing or damaged seal member upon or at the initial leak detection step and prior to filling the system with refrigerant. 
       SUMMARY OF THE INVENTION 
       [0010]    The present invention is a leak detection mechanism for use with a pressurized system, such as an air conditioning system. In particular, the present invention provides a mechanism for detecting a leak between a component and a conduit connected to the component. The component has an outer surface. A port having an inner surface and a seal surface extends inward into the component. A fluid passageway extends from the outer surface of the component to a position spaced from the seal surface. In an embodiment thereof, the fluid passageway includes a slot located in an inner surface of the port. 
         [0011]    In a further embodiment, the conduit includes an end, an upset and an o-ring located on the conduit between the end and the upset. The conduit is placed in the port such that the o-ring engages the seal surface of the port and the upset contacts the component. The fluid passageway extends from the outer surface to the port and forms an opening in the port with the opening located between the seal surface and the upset. 
         [0012]    In accordance with the present invention, the fluid passageway provides fluid communication between the port and the outer surface and bypasses any temporary or limited seal formed between the upset and the component. Thus, the fluid passageway forms a leak path if the o-ring is not present. The present invention leaves the o-ring seat or seal surface undisturbed whereby the o-ring seals the conduit/component interface when the o-ring is present. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is an exploded perspective view of a conduit to component fitting having a leak detection mechanism according to the present invention. 
           [0014]      FIG. 2  is a perspective sectional view of the component alone. 
           [0015]      FIG. 3  is a side view of the conduit and connection plate spaced from the component and in the process of being attached. 
           [0016]      FIG. 4  is a side view of the conduit and connection plate attached to the component. 
           [0017]      FIG. 5  is an enlarged cross-section of circle  5  of  FIG. 4 . 
           [0018]      FIG. 6  is the enlarged cross section of circle  5  with the o-ring removed. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]    Referring now to  FIG. 1 , an embodiment of the leak detection mechanism, seen generally at  10  according to the present invention is shown. The mechanism  10  includes a high-pressure line or inlet conduit  12  and a suction line or outlet conduit  14 , a connector plate  16 , threaded fastener  18  and an air conditioning (A/C) system component  20 , such as an expansion valve. The inlet conduit  12  and outlet conduit  14  are connected to the component  20  and correspondingly provide a supply and return line for a pressurized fluid, such as a refrigerant used in the A/C system. 
         [0020]    The component  20  has an outer surface  22 . The outer surface  22  contains an inlet port  24  and an outlet port  26  through which the pressurized fluid flows as it travels into and out of the component  20 . Both the inlet port  24  and outlet port  26  include a counterbore  28  formed of a first annular surface  30  and an axial surface  32 . The inlet and outlet ports  24 ,  26  further include a second annular surface  34  and a third annular surface  36  that extends into the component  20  from the second annular surface  34 . Each of the ports  24 ,  26  connect with the respective bores,  38 ,  40  whereby fluid flows through the component  20 . 
         [0021]    The inlet conduit  12  and outlet conduit  14  each include an upset  42  and an end  44 . A seal member, such as an o-ring  46 , is located on the respective ends  44  of the inlet conduit and outlet conduits  12 ,  14  adjacent to the upset  42 . To connect the inlet and outlet conduits  12 ,  14  to the component  20 , the ends  44  of the inlet conduit  12  and outlet conduit  14  are slidably inserted into the respective inlet port  24  and outlet port  26  such that the ends  44  of the inlet and outlet conduits  12 ,  14  engage the third annular surfaces  36  of each of the inlet and outlet ports  26 . The upsets  42  engage the counterbores  28  on each of the inlet and outlet ports  24 ,  26  and limit travel of the inlet and outlet conduits  12 ,  14 . As illustrated in  FIG. 4  the o-rings  46  located on the ends  44  of the conduits  12 ,  14  create an annular seal by engaging the second annular surfaces  34 . As known in the art, the connector plate  16  and threaded fastener  18  provide a compressive force on the upset  42  to hold the respective inlet and outlet conduits  12 ,  14  in position on the component  20 . 
         [0022]    Referring now to the inlet conduit  12  and corresponding inlet port  24 , as the conduit  12  is inserted into the port  24  the end of the conduit  12  enters the passageway or bore  48  defined by the third annular surface  36 . The end of the conduit  12  continues to travel within the bore  48  until the upset  42  is located in the counterbore  28  formed by the first annular surface  30  and the axial surface  32 . The second annular surface  34  includes a seal surface  54  that cooperates with the o-ring  46  located on the end  44  of the conduit  12  to form an annular seal and prevent leakage at the conduit  12  and port  24  interface. As illustrated in  FIGS. 5-6 , the port  24  includes a passageway shown as a slot  50  extending radially outward from the first annular surface  30 . The slot  50  extends along the inner surface of the port  24  from the outer surface  22  of the component  20  to the second annular surface  34  and creates an opening  52  in the second annular surface  34 . 
         [0023]    The slot  50  and correspondingly the opening  52  in the second annular surface  34  does not interfere with the sealing capability of the o-ring  46 , since the opening  52  formed in the second annular surface  34  is located between the o-ring  46  and the upset  42 . As illustrated in  FIG. 5 , seal surface  54 , that is the area or surface of the second inner surface  34  contacted by the o-ring  46 , is spaced from the opening  52  located in the second annular surface  34 . Accordingly, the O-ring  46  contacts the seal surface  54  and prevents any pressurized fluid from passing through the slot  50 . 
         [0024]    In those cases where the O-ring  46  is a missing or improperly installed, a temporary or limited seal can be created when the conduit  12  is connected to the component  20 . The temporary or limited seal results from the upset  42  engaging the first annular surface  30 , the axial surface  32  or both. For example, depending upon tolerances tightening the fastener  18  and corresponding connection plate  16  compresses the upset  42  against one of the surfaces of the counterbore  28  and creates a temporary or limited seal. Prior to filling the system with refrigerant, a leak test, that includes drawing a vacuum on the system, is conducted. The temporary or limited seal is often sufficient to result in the A/C system passing the leak test. Accordingly, the A/C system is filled with refrigerant, which over time leaks out causing repair and warranty concerns. 
         [0025]    As illustrated in  FIG. 6 , the slot  50  provides a predetermined leak path, illustrated by the arrow  56 . Accordingly, when the O-ring  46  is missing, the leak testing equipment cannot draw a vacuum as it draws air through the slot  50  into the A/C system during the leak test. Since drawing air through the slot  52  prevents drawing a vacuum the slot provides a mechanism whereby the A/C system does not past the leak test if the o-ring  46  is missing. Accordingly, the present invention provides a leak detection mechanism, in the form of a passageway or slot  50  extending between the seal surface  54 , that portion of the second annular surface  34  contacted by the o-ring  46 , and the outer surface  22  of the component  20 . The passageway or slot  50  is only open or communicates with the interior of the A/C system when the seal element or o-ring  46  is missing. As disclosed, the opening  52  in the second annular surface  34  created by of the passageway or slot  50  is located between the seal surface  54  and the upset  42  on the conduit  12 . 
         [0026]    While illustrated herein as a slot  50 , the passageway can take several forms including a bore, aperture or other opening that extends between the second annular surface  34  and the outer surface  22  of the component  20 . It should be understood that the slot  50  forms a predetermined leak path that circumvents any seal formed between the upset  42  and the inlet port  24 . Further, while the slot  50  is shown only used with the inlet port  24 , that is for illustrative purposes only, a slot  50  may also be used with the outlet port  26 . 
         [0027]    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. Such variations are not to be regarded as a departure from the spirit and scope of the invention.