Abstract:
A line fitting employs blocks secured together with a stud and a nut and having gaskets or seals which militate against permeation of CO 2  when subjected to high pressures and high temperatures, the seals are also resistant to decompression damage.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]    This application claims the benefit of U.S. provisional patent application Serial No. 60/335,134, filed Nov. 1, 2001. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The invention relates to a fitting for joining tubing in a vehicle air conditioning system and more particularly to a line fitting wherein the air conditioning system refrigerant is CO 2  and the fitting militates against permeation/leakage of CO 2  in the high pressures and high temperatures experienced during operation of the CO 2  air conditioning system.  
         BACKGROUND OF THE INVENTION  
         [0003]    In assembly line manufacturing of vehicles, it is desirable that line fittings in an air conditioning system can be secured using a power nut driver rather than using a torque wrench. For this reason, peanut (i.e., block) fittings are often employed.  
           [0004]    Conventional air conditioning systems have employed various refrigerants (e.g., Freon and R134a) having modest pressure and temperature ranges. Newer air conditioning and heat pump systems are being developed which use CO 2  as the refrigerant. The CO 2  systems operate at much higher pressures and temperatures. Fittings used for conventional systems typically employ rubber seals (e.g., O-rings) and cannot be used in CO 2  systems because of high permeation and decompression damage to the seals.  
           [0005]    It would be desirable to produce a fitting for use in an air conditioning system which militates against permeation of CO 2  and decompression damage to seals in high pressure and high temperature systems.  
         SUMMARY OF THE INVENTION  
         [0006]    Consistent and consonant with the present invention, a fitting for use in an air conditioning system which militates against permeation of CO 2  and decompression damage to seals in high pressure and high temperature systems has surprisingly been discovered. The fitting of the present invention employs blocks secured together using a stud, a nut, and gaskets or seals having a low permeation to CO 2 , an ability to withstand high operating pressures and temperatures, and a resistance to decompression damage.  
           [0007]    The block fitting for a CO 2  air conditioning system comprises:  
           [0008]    a male block including a first aperture having a first end and a second end, the first end of the first aperture of the male block is adapted to receive a tube end therein, the male block including a female annular bore surrounding the first aperture to form a channel having a generally u-shaped cross-section;  
           [0009]    a female block including a first aperture having a first end and a second end, the first end of the first aperture of the female block is adapted to receive a tube end therein, the female block including an annular collar surrounding the first aperture of the female block and adapted to be inserted into the channel formed by the female annular bore of the male block, at least one of an inner surface of the annular collar and an inner surface of the channel having an annular groove formed therein, the first aperture of the male block and the first aperture of the female block being substantially concentrically aligned;  
           [0010]    a primary seal disposed adjacent and surrounding the second end of the first aperture of the male block and adjacent and surrounding the second end of the first aperture of the female block;  
           [0011]    a secondary seal disposed in the annular groove of the annular collar of the female block, the secondary seal comprising a material with low permeation to CO 2 ; and  
           [0012]    a fastener adapted to engage the male block and the female block to sealingly engage the female annular bore of the male block and the annular collar of the female block. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]    The above, as well as other objects, features, and advantages of the present invention will be understood from the detailed description of the preferred embodiments of the present invention with reference to the accompanying drawings, in which:  
         [0014]    [0014]FIG. 1 is a sectional elevation view incorporating the features of the present invention;  
         [0015]    [0015]FIG. 2 is a sectional elevation view of an alternate embodiment of the present invention;  
         [0016]    [0016]FIG. 3 is a sectional elevation view of an alternate embodiment of the present invention;  
         [0017]    [0017]FIG. 4 is a sectional elevation view of an alternate embodiment of the present invention; and  
         [0018]    [0018]FIG. 5 is a sectional elevation view of an alternate embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]    Referring now to the drawings, and particularly FIG. 1, there is shown generally at  10  a block or peanut fitting incorporating the features of the invention. The block fitting  10  includes a male block portion  12  and a female block portion  14 . The male block  12  includes a first aperture  16  having a generally circular cross section and one end adapted to receive a tube or conduit  18 . It is desirable, although not critical, to have a press fit between the tube  18  and the wall forming the first aperture  16 . Splines formed on the wall which forms the first aperture  16  can also be used to accomplish the desired interference fit. The tube  18  is joined to the male block  12  by any conventional method such as by brazing or welding, for example, to form a leak free connection. The male block  12  includes a second aperture  20  adapted to receive a stud  22 .  
         [0020]    A female annular bore  24  is formed in the male block  12  and is adapted to receive an annular collar  26  formed on the female block  14 . An annular groove  28  is formed on an inner wall  30  of the collar  26 . The groove  28  is adapted to receive seal  32 , which serves as a secondary seal. It is understood that the groove  28  could also be formed on a wall of the female annular bore  24  or an outer wall of the collar  26 . A flat washer  31  is disposed between the male block  12  and the female block  14  adjacent the first aperture  16  to serve as a primary seal. Sealing beads  33  are formed on opposing surfaces of the male block  12  and the female block  14  to abut the flat washer  31 . In the embodiment shown, a tin-coated copper flat washer  31  is used. However, it is understood that other conventional CO 2  resistant sealing materials could be used such as laminated tetrafluoroethylene, rubber-coated aluminum, pewter, babbit, bronze, nickel, polyamide, aluminum, and other metal coated or rubber-coated metals, for example. Other sealing bead  33  shapes can be used such as curved radius, square, or other shapes and can employ one or more beads  33 .  
         [0021]    The female block  14  includes a first aperture  34  having a generally circular cross section and one end adapted to receive a tube or conduit  36 . The tube  36  is joined to the female block  14  by any conventional method such as by brazing or welding, for example, to form a leak free connection. The female block  14  includes a second aperture  38  adapted to receive the stud  22 . The stud  22  is inserted through the second aperture  38  of the female block  14  and the second aperture  20  of the male block  12 . A nut  40  threadingly engages the stud  22  to tightly hold the male block  12  adjacent the female block  14  and hold the first aperture  16  of the male block  12  adjacent and substantially concentric with the first aperture  34  of the female block  14 . It is understood that other fasteners could be used without departing from the scope and spirit of the invention.  
         [0022]    Referring now to FIG. 2, there is shown generally at  50  a block or peanut fitting incorporating a second embodiment of the present invention. The block fitting  50  includes a male block portion  52  and a female block portion  54 . The male block  52  includes a first aperture  56  having a generally circular cross section and one end adapted to receive a tube or conduit  58 . It is desirable, although not critical, to have a press fit between the tube  58  and the wall forming the first aperture  56 . Splines formed on the wall forming the first aperture  56  can also be used to accomplish the desired interference fit. The tube  58  is joined to the male block  52  by any conventional method such as by brazing or welding, for example, to form a leak free connection. The male block  52  includes a second aperture  60  adapted to receive a stud  62 .  
         [0023]    An annular shoulder  64  is formed on the male block  52  and is adapted to receive an annular collar  66  formed on the female block  54 . A ring seal or washer  68  is disposed within the annular collar  66  of the female block  54  and abuts the end of the shoulder  64  of the male block  52 . Sealing beads  69  are formed on opposing surfaces of the male block  52  and the female block  54  to abut the seal  68 . In the embodiment shown, a tin-coated copper seal  68  is used. However, it is understood that other conventional CO 2  resistant sealing materials could be used such as laminated tetrafluoroethylene, rubber-coated aluminum, pewter, babbit, bronze, nickel, polyamide, aluminum, and other metal coated or rubber-coated metals, for example. Other seal  68  cross sections can also be used without departing from the scope and spirit of the invention such as rectangular, triangular, and oval or various other radial curves, for example. Other sealing bead  69  shapes can be used such as curved radius, square, or other shapes and can employ one or more beads  69 .  
         [0024]    The female block  54  includes a first aperture  70  having a generally circular cross section and one end adapted to receive a tube or conduit  72 . The tube  72  is joined to the female block  54  by any conventional method such as by brazing or welding, for example, to form a leak free connection. The female block  54  includes a second aperture  74  adapted to receive the stud  62 . The stud  62  is inserted through the second aperture  60  of the male block  52  and the second aperture  74  of the female block  54 . A nut  76  threadingly engages the stud  62  to tightly hold the male block  52  adjacent the female block  54  and hold the first aperture  56  of the male block  52  adjacent and substantially concentric with the first aperture  70  of the female block  54 . It is understood that other fasteners could be used without departing from the scope and spirit of the invention.  
         [0025]    Referring now to FIG. 3, there is shown generally at  80  a block or peanut fitting incorporating a third embodiment of the present invention. The block fitting  80  includes a clamping block portion  82  and a female block portion  84 . The clamping block  82  includes a first aperture  86  with a generally circular cross section and adapted to receive a hollow tube end form  88 . The tube end form  88  has an annular shoulder  90  formed on an outer surface thereof. A central aperture  92  of the tube end form  88  has one end adapted to receive a tube or conduit  94 . It is desirable, although not critical, to have a press fit between the tube  94  and the wall forming the central aperture  92 . Splines formed on the wall forming the central aperture  92  can also be used to accomplish the desired interference fit. The tube  94  is joined to the tube end form  88  by any conventional method such as by brazing or welding, for example, to form a leak free connection. The clamping block portion  82  includes a second aperture  96  adapted to receive a stud  98 .  
         [0026]    The female block  84  includes a first aperture  100  having a generally circular cross section and a first end adapted to receive a tube or conduit  102 . The tube  102  is joined to the female block  100  by any conventional method such as by brazing or welding, for example, to form a leak free connection. A second end of the first aperture  100  is adapted to receive the tube end form  88 . The second end of the first aperture  100  has a sloped inner surface  104  adapted have a flare washer or seal  106  inserted therein and to abut the end of the tube end form  88 . In the embodiment shown, a tin-coated copper seal is used. However, it is understood that other conventional CO 2  resistant sealing materials could be used such as laminated tetrafluoroethylene, rubber-coated aluminum, pewter, and other rubber-coated metals, for example. Additionally, in the embodiment shown, the slope angle of the sloped inner surface is approximately 37 degrees. It is understood that other slope angles could be used without departing from the scope and spirit of the invention.  
         [0027]    The female block  84  includes a second aperture  108  adapted to receive the stud  98 . The stud  98  is inserted through the second aperture  96  of the clamping block  82  and the second aperture  108  of the female block  84 . A nut  110  threadingly engages the stud  98  to urge the clamping block  82  and the tube end form  88  adjacent the female block  84  and form a tight seal. Hence, the central aperture  92  of the tube end form  88  is held adjacent and substantially concentric with the first aperture  100  of the female block  84 . It is understood that other fasteners could be used without departing from the scope and spirit of the invention.  
         [0028]    Referring now to FIG. 4, there is shown generally at  120  a block or peanut fitting incorporating a fourth embodiment of the present invention. The block fitting  120  includes a male block portion  122  and a female block portion  124 . The male block  122  includes a first aperture  126  having a generally circular cross section and one end adapted to receive a tube or conduit  128 . It is desirable, although not critical, to have a press fit between the tube  128  and the wall forming the first aperture  126 . Splines formed on the wall forming the first aperture  126  can also be used to accomplish the desired interference fit. The tube  128  is joined to the male block  122  by any conventional method such as by brazing or welding, for example, to form a leak free connection. The male block  122  includes a second aperture  130  adapted to receive a stud  132 .  
         [0029]    A tapered end surface  134  is formed on the male block  122  and is adapted to be received in an annular collar  136  formed on the female block  124 . A seal  138  is disposed on a facing surface  140  of the female block  124  and abuts a facing surface  142  of the male block  122 . The seal  138  has a sealing bead  144  disposed thereon. In the embodiment shown, a rubber coated metal seal is used. However, it is understood that other conventional CO 2  resistant sealing materials could be used such as laminated tetrafluoroethylene, tin-coated copper, and pewter, for example.  
         [0030]    The female block  124  includes a first aperture  146  having a generally circular cross section and one end adapted to receive a tube or conduit  148 . The tube  148  is joined to the female block  124  by any conventional method such as by brazing or welding, for example, to form a leak free connection. The female block  124  includes a second aperture  150  adapted to receive the stud  132 . The stud  132  is inserted through the second aperture  130  of the male block  122  and threadingly engaged in the second aperture  150  of the female block  124 . A nut  152  threadingly engages the stud  132  to tightly hold the male block  122  adjacent the female block  124  and hold the first aperture  126  of the male block  122  adjacent and substantially concentric with the first aperture  146  of the female block  124 . It is understood that other fasteners could be used without departing from the scope and spirit of the invention.  
         [0031]    Referring now to FIG. 5, there is shown generally at  160  a block or peanut fitting incorporating a fifth embodiment of the present invention. The block fitting  160  includes a male block portion  162  and a female block portion  164 . The male block  162  includes a first aperture  166  having a generally circular cross section and one end adapted to receive a tube or conduit  168 . It is desirable, although not critical, to have a press fit between the tube  168  and the wall forming the first aperture  166 . Splines formed on the wall forming the first aperture  166  can also be used to accomplish the desired interference fit. The tube  168  is joined to the male block  162  by any conventional method such as by brazing or welding, for example, to form a leak free connection. The male block  162  includes a second aperture  170  adapted to receive a stud  172 .  
         [0032]    A generally spherical end surface  174  is formed on the male block  162  and is adapted to be received in a generally spherical socket  176  formed on the female block  164 . A seal  178  is disposed between the spherical end surface  174  and the spherical socket  176 . The seal  178  also extends to essentially cover the full interface area between the male block  162  and the female block  164 . The seal  178  has a first aperture  180  and a second aperture  182  formed therein. In the embodiment shown, a rubber coated metal seal is used. However, it is understood that other conventional CO 2  resistant sealing materials could be used such as laminated tetrafluoroethylene, tin coated copper, polyimide, rubber, and soft metal, for example.  
         [0033]    The female block  164  includes a first aperture  184  having a generally circular cross section and one end adapted to receive a tube or conduit  186 . The tube  186  is joined to the female block  164  by any conventional method such as by brazing or welding, for example, to form a leak free connection. The female block  164  includes a second aperture  188  adapted to receive the stud  172 . The stud  172  is inserted through the second aperture  170  of the male block  162 , the second aperture  182  of the seal  178 , and the second aperture  188  of the female block  164 . A nut  190  threadingly engages the stud  172  to tightly hold the male block  162  adjacent the female block  164  having the seal  178  sandwiched therebetween. The first aperture  166  of the male block  162  is also held adjacent and substantially concentric with the first aperture  180  of the seal  178  and the first aperture  184  of the female block  164 . The radius of the spherical portion of the seal  178  may be slightly larger than that of the spherical end surface  174  to provide a good fit and good sealing. The spherical shape allows the male block  162  and the female block  164  to be slightly misaligned during assembly and still achieve a good seal as the spherical surface is naturally guided to nest properly when the nut  190  is secured. It is understood that other fasteners could be used without departing from the scope and spirit of the invention.  
         [0034]    The assembly and operation of the embodiments of the invention will now be described. To assemble the embodiment of the invention illustrated in FIG. 1, the tube  18  is inserted in the first aperture  16  of the male block  12  and secured. The tube  36  is inserted in the first aperture  34  of the female block  14  and secured. The stud  22  is then threadingly engaged with the second aperture  20  of the male block  12 . The flat washer  31  is placed within the annular collar  26  formed on the female block  14  and generally concentric with the first aperture  16  of the male block  12  and the first aperture  34  of the female block  14 . Then, the seal  32  is placed in the annular channel  28 . The male block  12  and the female block  14  are moved adjacent one another allowing the stud  22  to slide through the second aperture  38  of the female block  14 . The nut  40  is then engaged with the threaded portion of the stud  22  and tightened to sealingly engage the male block  12  and the female block  14 . Once assembled, the male block  12  and the female block  14  cooperate with the flat washer  31  and the seal  32  to create a sealed, tight fit and militate against relative axial and rotational movement between the tube  18  and the tube  36 . A sealing pressure of about 7200 psi (50 Mpa) at 8 Nm torque, with 600 lbf clamp load has been achieved. This embodiment has resulted in successful leak testing using CO 2  at 15 Mpa and 180 degrees Celsius.  
         [0035]    To assemble the embodiment of the invention illustrated in FIG. 2, the tube  58  is inserted in the first aperture  56  of the male block  52  and secured. The tube  72  is inserted in the first aperture  70  of the female block  54  and secured. The stud  62  is then threadingly engaged with the second aperture  74  of the female block  54 . Then, the seal  68  is press fit into the annular collar  66 . The male block  52  and the female block  54  are moved adjacent one another allowing the stud  62  to slide through the second aperture  60  of the male block  52 . The nut  76  is then engaged with the threaded portion of the stud  62  and tightened to sealingly engage the male block  52  and the female block  54 . Once assembled, the male block  52  and the female block  54  cooperate with the seal  68  to create a sealed, tight fit and militate against relative axial and rotational movement between the tube  58  and the tube  72 . The male block  52  and the female block  54  are typically clamped with about 600 lbf clamping load on the seal  68  resulting in about 9700 psi (66 Mpa) of sealing pressure with 8 Nm of torque on the nut. This embodiment has resulted in a successful leak test using CO 2  at 15 Mpa and 180 degrees Celsius.  
         [0036]    For the embodiment of the invention illustrated in FIG. 3, the tube  94  is inserted in the central aperture  92  of the tube end form  88  and secured. The tube  102  is inserted in the first aperture  100  of the female block  84  and secured. Then, the flare washer  106  is placed within the sloped inner surface,  104 . The tube end form  88  is inserted into the first aperture  86  of the clamping block  82  and the clamping block  82  and the female block  84  are moved adjacent one another. Then, the stud  98  is inserted into the second aperture  96  of the clamping block  82  and threadingly engaged with the second aperture  108  of the female block  84 . The nut  110  is then engaged with the threaded portion of the stud  98  and tightened to sealingly engage the tube end form  88  and the female block  84 . Once assembled, the clamping block  82 , the tube end form  88 , and the female block  84  cooperate with the flare washer  106  to create a sealed, tight fit and militate against relative axial and rotational movement between the tube  94  and the tube  102 . Using a tin coated copper washer with this embodiment has resulted in a successful leak test using helium at 900 psig.  
         [0037]    To assemble the embodiment of the invention illustrated in FIG. 4, the tube  128  is inserted in the first aperture  126  of the male block  122  and secured. The tube  148  is inserted in the first aperture  146  of the female block  124  and secured. Then, the seal  138  is placed adjacent the facing surface  140  of the female block  124  within the annular collar  136 . The male block  122  and the female block  124  are then moved adjacent one another. The stud  132  is inserted into the second aperture  130  of the male block  122  and threadingly engaged with the second aperture  150  of the female block  124 . The nut  152  is then engaged with the threaded portion of the stud  132  and tightened to sealingly engage the male block  122  and the female block  124 . Once assembled, the male block  122  and the female block  124  cooperate with the seal  138  to create a sealed, tight fit and militate against relative axial and rotational movement between the tube  128  and the tube  148 . A sealing pressure of about 7200 psi (50 Mpa) at 8 Nm torque, with 600 lbf clamp load has been achieved. This embodiment has resulted in successful leak testing using helium at 900 psig.  
         [0038]    For the assembly of the embodiment of the invention illustrated in FIG. 5, the tube  168  is inserted in the first aperture  166  of the male block  162  and secured. The tube  186  is inserted in the first aperture  184  of the female block  164  and secured. Then, the seal  178  is placed within the spherical socket  176 . The male block  162  and the female block  164  are moved adjacent one another to trap the seal  178  therebetween. The stud  172  is then inserted into the second aperture  170  of the male block  162 , the second aperture  182  of the seal  178 , and threadingly engages the second aperture  188  of the female block  164 . The nut  190  is then engaged with the threaded portion of the stud  172  and tightened to sealingly engage the male block  162  and the female block  164 . Once assembled, the male block  162  and the female block  164  cooperate with the seal  178  to create a sealed, tight fit and militate against relative axial and rotational movement between the tube  168  and the tube  186 . Use of this embodiment has resulted in successful leak testing using helium at 900 psig with a torque on the nut  190  of approximately 20 Nm.  
         [0039]    From the foregoing description, one ordinarily skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications to the invention to adapt it to various usages and conditions.