Abstract:
A fitting, such as an anti-blowback fitting, that includes a friction reducing device that enables easy removal of the fitting from a high pressure connection such as one associated with an HVAC unit. When used in connection with refrigeration, anti-blow back fittings function to keep the refrigerant in the hose to which it is connected in order to minimize or prevent the refrigerant from escaping to the environment. In certain embodiments, a friction reducing device is positioned in the fitting, and decreases the load on the rear housing, which enables easy rotation of the outer or swivel housing of the fitting to remove the same from the high pressure connection. In certain embodiments, the friction reducing device is a thrust bearing.

Description:
[0001]    This application is a Continuation of U.S. patent application Ser. No. 13/804,344 filed Mar. 14, 2013, the disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    Mechanical air conditioning and refrigeration are accomplished by continuously circulating, evaporating, and condensing a fixed supply of refrigerant in a closed system. Charging or recharging an air conditioning or refrigeration system with refrigerant is done through the low side suction intake fitting with the use of manifold gauges and service hoses. There are several types of refrigerants used and some can be charged as a vapor and others must be charged as a liquid. 
         [0003]    For example, R-410A is replacing R-22 refrigerant and is a mixture of HFC-32 and HFC-125, and is thus considered to be zeotropic. Zeotropic refrigerants such as R-410A must be charged as a liquid from a canister due to the possibility of fractionation of the blend of refrigerants it contains. The range of temperatures at which components in the blended components of R-410A refrigerant boil (temperature glide) is &lt;0.3° F., making it a near-azeotropic refrigerant mixture. 
         [0004]    Since the different components of zeotropic refrigerants such as R-410A have different boiling points, the components fractionate during boiling. That is, as the temperature increases, the lower boiling point components vaporize first. The vapor thus has a higher concentration of the lower boiling components than the liquid, and a lower concentration of the higher boiling components. When such a fluid blend is stored in a closed container in which there is a vapor space above the liquid, the composition of the vapor is different from the composition of the liquid. If the fluid is then removed from the container to charge an air conditioning system, for example, fractionation can take place, with accompanying changes in composition. Such changes can cause a refrigerant to have a composition outside of specified limits, to have different performance properties or even to become hazardous, such as by becoming flammable. 
         [0005]    In general, R-410A pressures are 1.8 times higher than those of R-22, and can be over 600 psi. CO 2  is an example of another refrigerant gas that can run at a much higher pressure, as high as 1800 psi or more. 
         [0006]    Low-pressure vapor refrigerant is compressed and discharged from the compressor as a high temperature, high-pressure, “superheated” vapor or liquid. The high-pressure refrigerant flows to the condenser, where it is changed to a low temperature, high-pressure liquid. It then flows through a filter dryer to a thermal expansion valve or TXV. The TXV meters the correct amount of liquid refrigerant into an evaporator. As the TXV meters the refrigerant, the high-pressure liquid changes to a low pressure, low temperature, saturated liquid/vapor. This saturated liquid/vapor enters the evaporator and is changed to a low pressure, dry vapor. The low pressure, dry vapor is then returned to the compressor. The cycle then repeats. 
         [0007]    Because of the relatively high pressures involved, difficulties have arisen in removing fittings, such as anti-blowback fittings, coupled to high pressure, such as the hose connecting the high side of a refrigeration unit to the refrigerant source. The high pressure puts force on the connection, making it difficult to remove the fitting, especially manually. 
         [0008]    It therefore would be desirable to provide a fitting that is easily removed from a high-pressure connection. It would be particularly desirable to provide a fitting that is easily removed from a high-pressure connection manually, i.e., without the need for a tool to apply torque to the fitting greater than can be applied by hand. 
       SUMMARY 
       [0009]    The shortcomings of the prior art have been overcome by the embodiments disclosed herein, which relate to a fitting, such as an anti-blowback fitting, that includes a friction reducing device that enables easy removal of the fitting from a high-pressure connection such as that associated with an HVAC unit. When used in connection with refrigeration, anti-blow back fittings function to keep the refrigerant in the hose to which it is connected in order to minimize or prevent the refrigerant from escaping to the environment. 
         [0010]    In certain embodiments, a friction reducing device is positioned in the fitting, and enables easy rotation of the outer housing of the fitting despite the axial load resulting from the high pressure connection, to remove the same from the high-pressure connection by hand and without the need for tools to supply sufficient torque. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is an exploded view of a fitting in accordance with certain embodiments; 
           [0012]      FIG. 2  is a cross-sectional view of the fitting of  FIG. 1  in accordance with certain embodiments; 
           [0013]      FIG. 3  is a cross-sectional view of a swivel housing in accordance with certain embodiments; 
           [0014]      FIG. 4  is a cross-sectional view of a front housing in accordance with certain embodiments; 
           [0015]      FIG. 5A  is a cross-sectional view of a depressor in accordance with certain embodiments; 
           [0016]      FIG. 5B  is a top view of the depressor of  FIG. 5A ; 
           [0017]      FIG. 6  is a cross-sectional view of a rear housing in accordance with certain embodiments; 
           [0018]      FIG. 7  is a cross-sectional view of a friction reducing device in accordance with certain embodiments; 
           [0019]      FIG. 8  is a cross-sectional view of a retaining member in accordance with certain embodiments; 
           [0020]      FIG. 9  is an exploded view of a fitting in accordance with another embodiment; 
           [0021]      FIG. 10  is a cross-sectional view of the fitting of  FIG. 9 ; 
           [0022]      FIG. 11  is an exploded view of a fitting in accordance with yet another embodiment; and 
           [0023]      FIG. 12  is a cross-sectional view of the fitting of  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    Turning first to  FIGS. 1 and 2 , there is shown a fitting  10 , which in the embodiment shown, is an anti-blowback fitting. In accordance with certain embodiments, the fitting  10  includes an outer or swivel housing  12 , front housing  14 , depressor  16 , biasing member  18 , rear housing  20 , friction reducing device  22 , and retaining member  24 . 
         [0025]    As best seen in  FIG. 3 , in accordance with certain embodiments the swivel housing  12  is generally cylindrical, and includes an internal cavity  28 . The distal end  12 A of the swivel housing  12  has a central bore  30  that is internally threaded so that it can mate with a corresponding threaded male member on the HVAC unit (not shown) to connect the fitting to the unit. The central bore  30  is in fluid communication with the internal cavity  28 , and has an inner diameter less than the inner diameter of the central bore  30 . Near the proximal end  12 B of the swivel housing  12  there is formed an internal annular groove  29  to receive retaining member  24  as discussed in greater detail below. In certain embodiments, the internal cavity  28  houses the front housing  14 , the depressor  16 , the biasing member  18 , a portion of the rear housing  20 , the friction reducing device  22 , and the retaining member  24 . 
         [0026]    In accordance with certain embodiments,  FIG. 4  shows a front housing  14  that is generally cylindrical and has an outer diameter smaller than the inner diameter of the swivel housing  12  so that the front housing  14  fits inside the swivel housing  12 , as seen in  FIG. 2 . In certain embodiments, the housing  14  includes a distal end  35 A having a region with internal threads  31 , and a proximal end  35 B with flanges  14 A,  14 B that extend radially inwardly from the end as shown. The flanges  14 A,  14 B retain O-ring  65  as seen in  FIG. 2 . An intermediate region includes flange members  14 C,  14 D, each having a main body that extends radially inwardly. Leg  14 E extends axially from the main body of flange  14 C in the direction of the distal end  35 A, and leg  14 F extends axially from the main body of flange  14 D in the direction of the distal end  35 A. 
         [0027]    In accordance with certain embodiments,  FIGS. 5A and 5B  show a depressor  16  that is configured to be positioned inside the front housing  14  as shown in  FIG. 2 . The depressor  16  has a main body  41  that terminates at one end with a central axially extending member  42 . The main body  41  sits on a hollow hexagonal base  43  as seen in  FIG. 5B . When positioned in the front housing  14 , the outer wall of the main body  41  abuts the outer walls of the flange members  14 C,  14 D and legs  14 E,  14 F of the outer housing  14 , and a square seal  75  is positioned on the shoulder  44  and free distal end  55  of the rear housing  20 . ( FIG. 2 ). The depressor  16  is normally urged axially towards the distal end  30  of the swivel housing  12  by biasing member  18  that seats within the hollow region of the hexagonal base  43 , as best seen in  FIG. 2 . When the force of the biasing member  18  is overcome such as by connection of the fitting to a high pressure unit, the depressor is forced axially away from the distal end  12 A of the housing  12 . 
         [0028]    In accordance with certain embodiments,  FIG. 6  shows a rear housing  20 . The housing  20  includes at the distal end  54  an axially extending ring  51  having external threads  58  that mate with internal threads  31  in the front housing  14 . Extending axially from the ring  51  is a main body member  55 , which seats the biasing member  18  ( FIG. 2 ) and extends radially outwardly a distance greater than the diameter of the ring  51 . In certain embodiments, the opposite proximal end of the housing  20  is an elongated barbed member  52  formed with a plurality of barbs  53 A,  53 B,  53 C. Each barb is frusto conical in shape, tapering radially outwardly as it extends axially towards the distal end  54 . The barb member  52  receives a hose (not shown) or the like. The barb member  52  includes an elongated leg  56  that connects the barbed portion to the main body member  55 . The elongated leg  56  includes a region  57  of increased diameter  58  that is surrounded by friction reducing device  22  when in the assembled condition ( FIG. 2 ). The barbs on the housing  20  are not necessary; connection can be made to the housing  20  by other suitable means, such as threads or a quick coupler. 
         [0029]    In accordance with certain embodiments,  FIG. 7  illustrates an embodiment of the friction reducing device  22 . In the embodiment shown, the friction reducing device  22  is a thrust bearing that is a rotary type bearing that permits rotation between parts, while supporting an axial load. In accordance with certain embodiments, the thrust bearing includes outer washers  61 ,  62  that sandwich an inner cage  63 . The washers  61 ,  62  may be made of stainless steel or other suitable material, and the inner cage  63  of nylon or metal, for example. The washers  61 ,  62  and inner cage  63  each has a central bore  66  that align when in the assembled condition. The inner cage  63  has a plurality of apertures, each receiving a ball bearing  64  held in place by the outer washers  61 ,  62 . Although a thrust ball bearing is illustrated, those skilled in the art will appreciate that other types of friction reducers may be used, such as thrust roller bearings, slip washers or plates, or other known friction reducing members as discussed in greater detail below. The slip washers or plates can be made of or coated with polytetrafluoroethylene (Teflon®) or the like, for example. The friction reducing device  22  is positioned in the swivel housing  12  such that it abuts against the rear wall of the main body member  55  of the rear housing  20 , and the region  57  of the main body member  55  is received in the central bore  66  of the device  22 , as best seen in  FIG. 2 . The upstream outer washer  62  rotates with the swivel housing  12 , while the downstream outer washer  61  does not. This reduces friction between swivel housing  12 , rear housing  20  and retaining member  24 , and allows for manual rotation of the swivel housing despite the axial load caused by the high pressure connection. 
         [0030]    In accordance with certain embodiments,  FIG. 8  shows a retaining member  24 . The retaining member  24  is resilient, preferably made of steel, and is force fit into annular groove in the swivel housing  12 . It abuts against the friction reducing device  22  and retains it in place in the fitting  10 . 
         [0031]    The swivel housing  12  is rotatable relative to the depressor  16 , the front housing  14 , the biasing member  18 , the rear housing  20 , and a portion of the friction reducing device  22 . 
         [0032]      FIGS. 9 and 10  illustrate another embodiment of the friction reducing device. In accordance with certain embodiments, the friction reducing device  222  of  FIGS. 9 and 10  is a needle roller bearing  221 , made of stainless steel, for example, sandwiched by downstream washer  261  and upstream washer  263 . The washers  261  and  263  can be made of plastic. In certain embodiments, the needle rollers are equally spaced by means of a cage whose web section separates the rollers and provides guidance to keep them tracking in an orbital path. It transmits thrust loads between two relatively rotating objects while reducing friction. 
         [0033]      FIGS. 11 and 12  illustrate another embodiment of the friction reducing device. In accordance with certain embodiments, the friction reducing device  322  of  FIG. 10  and is a thrust bearing washer  321 , made of plastic, for example, sandwiched by downstream washer  361  and upstream washer  363 . The washers  361  and  363  also can be made of plastic. 
         [0034]    In operation in certain embodiments, the fitting  10  is coupled to a hose or the like which is connected to an access fitting on the unit being serviced or the refrigerant source (or a vacuum pump) and whose other end is connected to a refrigerant charging manifold. In certain embodiments, the connection to the access fitting (or refrigerant source or vacuum pump), for example, is connected via internal threads in the swivel housing  12  that mate with an access fitting containing a Shrader valve (not shown) or the like. The Shrader valved access fitting or the like has a pin that contacts and depresses depressor  16  against the force of biasing member  18 , moving the depressor  16  axially in a direction away from the access fitting, opening both the fitting  10  and the Shrader valve to create fluid communication between the hose and the unit being serviced. This axial movement opens a passageway between the perimeter of depressor  16  and the front housing  14  and distal end of rear housing  20 , allowing fluid to flow from the manifold through the fitting and into the hose or the like (not shown) attached to the fitting at the proximal end of rear housing. When the operation is complete, removal of the fitting from the high pressure connection can be carried out by manual rotation of the swivel housing  12 , due to the presence of the friction reducing device  22 ,  222 ,  322  which causes the depressor  16  to move axially way from the access fitting. The force of the biasing member  18  then causes the depressor  16  to move axially towards the proximal end of the swivel housing  12 , closing the passageway and blocking the flow of fluid. 
         [0035]    In certain embodiments, a Shrader valve is not necessary; the anti-blowback valve can be attached directly to a standard access fitting provided the fitting is shaped to depress the depressor axially when in the assembled condition. 
         [0036]    The fitting disclosed herein reduces the torque required to remove it from connections under virtually any amount of pressure, and is especially advantageous the higher the pressure is. For example, at pressures of 500 psi, anti-blowback fittings with the friction reducing device required about 20% less torque (as measured with a torque wrench (inch-pounds)) to remove it from a connection than a conventional anti-blowback fitting devoid of a friction reducing device. At pressures of 600 psi, anti-blowback fittings with the friction reducing device required about 25% less torque (as measured with a torque wrench (inch-pounds)) to remove it from a connection than a conventional anti-blowback fitting devoid of a friction reducing device.