Abstract:
A muffler assembly for use in an air conditioning system includes a muffler conduit for receiving pressurized fluid and a valve in fluid communication with the muffler conduit. The valve is moveable between closed and open positions in response to a pressure differential in the muffler conduit. In one example, the valve includes a valve member and a magnetic member that magnetically influences movement of the valve member. In one example method of making a muffler assembly, the valve is arranged at least partially within the muffler conduit. The conduit includes first and second tube portions that are formed in a spinning operation.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     This invention relates to a muffler and, more particularly, to a compressor muffler.  
         [0002]     Commercial, residential and other air conditioning systems typically utilize a refrigerant to cool a space. A compressor pumps refrigerant gas to a condenser that permits the refrigerant gas to release heat to the surrounding environment as the refrigerant gas condenses (typically outdoors). Condensed refrigerant liquid circulates from the condenser to an evaporator (typically indoors). The refrigerant liquid expands within the evaporator and absorbs heat from air blowing over the evaporator. The refrigerant then circulates to the compressor and another cooling cycle begins.  
         [0003]     Typical air conditioning systems produce surges in refrigerant flow through the air conditioning system. A surge in refrigerant flow may occur because of cyclic variation in a discharge pressure of the refrigerant from the compressor. The variation in flow may cause undesirable noise and fluctuation in the cooling capacity of the air conditioning system.  
         [0004]     Disadvantageously, the air conditioning system may operate inefficiently because of refrigerant pressure loss. The pressure within the air conditioning system equalizes through a bleed valve near the compressor when the air conditioning system is shut off after operating for a time. When the air conditioning system is activated, the compressor operates for a period of time before there is enough build-up of refrigerant pressure to fully circulate the refrigerant through the air conditioning system. The compressor is operating but the air blowing over the evaporator may not be adequately cooled under this inefficient condition.  
         [0005]     Accordingly, there is a need for an assembly that muffles the surge in refrigerant flow and reduces refrigerant pressure loss. This invention addresses those needs and provides enhanced capabilities while avoiding the shortcomings and drawbacks of the prior art.  
       SUMMARY OF THE INVENTION  
       [0006]     A muffler assembly for use in an air conditioning system includes a muffler conduit for receiving the pressurized fluid and a valve in fluid communication with the muffler conduit. The valve is moveable between a closed position and an open position in response to a pressure differential in the muffler conduit.  
         [0007]     In one example, the valve includes a valve member and a magnetic member that magnetically influences movement of the valve member. The magnetic member biases the valve member to a closed position. The valve member is moved to an open position by the pressurized fluid when the pressure is great enough to overcome the magnetic attraction between the magnetic member and the valve member.  
         [0008]     In one example method of making the muffler assembly, the valve is arranged at least partially within the conduit. In one example, the conduit includes a tube that undergoes a spinning operation to form a tube end portion. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiment. The drawings that accompany the detailed description can be briefly described as follows.  
         [0010]      FIG. 1  schematically shows selected portions of an air conditioning system.  
         [0011]      FIG. 2  schematically shows selected portions of an example muffler assembly.  
         [0012]      FIG. 3  schematically shows selected portions of an example muffler assembly having a valve in an open position.  
         [0013]      FIG. 4  shows a perspective view of an example guide member of a valve of a muffler assembly.  
         [0014]      FIG. 5  schematically shows a cross-section of selected portions of a muffler assembly.  
         [0015]      FIG. 6  schematically shows selected portions of a muffler assembly during an example fabrication operation.  
         [0016]      FIG. 7  schematically shows selected portions of a muffler assembly during an example fabrication operation. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0017]      FIG. 1  schematically shows selected portions of an example air conditioning system  10 . The air conditioning system  10  includes a compressor  12  that pumps refrigerant through air conditioning lines  14  to a muffler assembly  16 . The muffler assembly  16  dampens surges of refrigerant flow from the compressor and a valve assembly  18  within the muffler assembly  16  prevents backflow of refrigerant into the compressor  12 . Refrigerant from the muffler assembly  16  is received in a condenser  20  that permits the refrigerant to release heat to the surrounding environment (e.g., outdoors). Condensed refrigerant circulates from the condenser  20  through an expansion device  23  and then to an evaporator  22 . The refrigerant expands in the evaporator  22  and absorbs heat from air blowing over the evaporator  22  to provide cool air to a space  24 , such as an office, residency, or other space. The refrigerant then circulates to the compressor  12  and another cooling cycle beings.  
         [0018]      FIG. 2  shows selected portions of an example muffler assembly  16  including a muffler conduit  30  through which the refrigerant flows. The muffler conduit  30  includes a tube  32  having a mixing portion  33 , an inlet tube portion  34  for receiving refrigerant from the compressor  12 , and an outlet tube portion  36  leading to the condenser  20 . In the example shown, the tube  32  has a larger cross-sectional area than the inlet tube portion  34  to promote mixing of the refrigerant and equalization of surge flow in the mixing portion  33 .  
         [0019]     The mixing portion  33  is of adequate volumetric size to equalize (i.e. muffle) surges of refrigerant flow from the compressor  12 . That is, surges of flow are mixed in the mixing portion  33  to form a more uniform flow of refrigerant. In one example, the extent to which the surges of flow are mixed in the mixing portion  33  depends on the volume of the mixing portion  33 . A smaller volume allows less mixing than a larger volume.  
         [0020]     In the illustrated example, the tube  32  includes dimples  38  that extend inwardly from the tube  32 . The valve assembly  18  abuts the dimples  38  such that the valve assembly  18  is prevented from moving axially past the dimples  38 . The dimples  38  provide the benefit of at least partially securing the valve assembly  18  in the tube  32  without additional fastening operations, such as bolt tightening.  
         [0021]     In the illustrated example, a seat member  56  of the valve assembly  18  is secured to an inner surface  42  of the tube  32  at a soldered joint  44 . In one example, the seat member  56  is positioned in the tube  32  and solder material is deposited into the soldered joint  44  to secure the seat member  56  to the inner surface  42 . The solder material forms a seal between the valve assembly  18  and the inner surface  42 .  
         [0022]     The valve assembly  18  includes a valve member  54  that moves between the seat member  56  and a guide member  58  in response to a pressure differential of the refrigerant across the valve assembly  18 , as will be described in more detail below. The seat member  56  includes a magnet  60  that is press-fit into an opening  62 , for example. In the example shown, the magnet  60  occupies less than a full cross-sectional area of the opening  62  such that refrigerant is permitted to flow through the opening  62  when the valve member  54  is open. The valve member  54  and guide member  58  are installed into the tube  32  and assembled to the seat member  56  after the seat member  56  is soldered.  
         [0023]     The magnet  60  magnetically attracts the valve member  54  such that the valve member  54  is biased to a closed position sealed against the seat member  56 . To move the valve member to an open position, a pressure of refrigerant in the mixing portion  33  overcomes the magnetic attraction and a pressure of refrigerant downstream of the valve assembly  18 . In one example, the downstream refrigerant pressure is greater than the magnetic attraction such that the refrigerant pressure in the mixing portion  33  primarily overcomes the downstream refrigerant pressure to open the valve member  54 .  
         [0024]     In the illustrated example, the valve member  54  is made of a ferrous material that is subject to the magnetic influence of the magnet  60 . This feature provides the advantage of attracting undesirable ferrous particles that are in the refrigerant, essentially removing the ferrous particles from the flow of refrigerant through the air conditioning system  10 . Given this disclosure, those of ordinary skill in the art will recognize additional configurations that utilize magnetic influence to control movement of a valve member to meet their particular needs.  
         [0025]     In the closed position, a pressure of refrigerant in the mixing portion  33  of the muffler assembly  16  is too low to overcome the downstream refrigerant pressure and the magnetic attraction between the magnet  60  and the valve member  54 . Thus the refrigerant is prevented from flowing back into the compressor  12  from the condenser  20  and evaporator  22 . In one example, this condition corresponds to the compressor being in an inactive state such that no refrigerant is being pumped from the compressor  12  to the muffler assembly  16 .  
         [0026]     In another example, the compressor  12  has just been activated but has not yet built up enough pressure in the mixing portion  33  to overcome the downstream refrigerant pressure and magnetic attraction to move the valve member  54  to an open position. This may provide the benefit of increased efficiency of the air conditioning system  10  compared to previously known systems. In previously known systems, a compressor has to build the refrigerant pressure in the entire volume of the air conditioning system to fully circulate the refrigerant. In the disclosed example, the valve assembly  18  prevents refrigerant from backflowing into the compressor  12  from the condenser  20  and the evaporator  22 . This in turn prevents refrigerant pressure loss through a bleed valve commonly located near the compressor  12  and prevents the compressor  12  from operating in reverse to expand the refrigerant. In the disclosed example, the compressor  12  only has to build the refrigerant pressure in the volume between the compressor  12  and the valve assembly  18  (i.e. less than the entire volume of the air conditioner system  10 ) in order to overcome the magnetic attraction and refrigerant pressure downstream from the valve assembly  18  to move the valve member  54  to an open position ( FIG. 3 ) to fully circulate the refrigerant.  
         [0027]     In the illustrated example, the guide member  58  includes spaced apart guide arms  64  that extend about the valve member  54 . Each of the spaced apart guide arms  64  includes a first face  66  that restricts movement of the valve member  54  in a radial direction with respect to a central axis A and a second face  68  that restricts axial movement of the valve member  54 . The guide arms  64  provide the advantage of maintaining alignment of the valve member  54  with the opening  62  of the seat member  56 .  
         [0028]     In the example shown, the spaced apart guide arms  64  mix the refrigerant as the refrigerant flows through the valve assembly  18 . The refrigerant flows in a tortuous path through the opening  62 , around the valve member  54  in a direction radial to the central axis A, between the spaced apart guide arms  64 , and then again along the direction D out of an opening  70  ( FIG. 4 ) in the guide member  58  to the outlet tube portion  36 .  
         [0029]      FIG. 5  schematically illustrates another cross-sectional view of an example tube  32 . In the illustrated example, the dimples  38  are formed at 90° intervals around the circumference of the tube  32  to provide balanced support of the valve assembly  18 . In one example, the dimples  38  are mechanically pressed into the tube  32  such that depressions  72  are left on the outside of the tube  32 . In another example, the valve assembly  18  is welded to the inner surface  44  of the tube  32  before forming the dimples  38 . The valve assembly  18  provides support of the tube  32  during the dimple forming process such that the walls of the tube  32  are prevented from buckling while the tube  32  is secured to form the dimples  38 .  
         [0030]      FIG. 6  schematically illustrates a method of making the muffler assembly  16 . In the illustrated example, the valve assembly  18  is installed into the tube  32  before forming the inlet tube portion  34 . This provides the benefit of allowing easier access to install the valve assembly  18  within the tube  32  rather than having to tediously install the valve assembly  18  through restrictive openings.  
         [0031]     In one example forming operation, a pilot member  78  is inserted along the central axis A into a tool  80 . The pilot member  78  includes a body portion  82  having a nominal dimension D 1  and an extended portion  84  having a smaller nominal dimension D 2 . The body portion  82  and extended portion  84  form a lip  86 . The nominal dimension D 1  corresponds to an inner diameter D 3  of an opening  88  of the tool  80  such that the pilot member  78  fits tightly within the opening  88 .  
         [0032]     The tube  32  is aligned along the central axis A and the tool  80  and pilot member  78  are rotated (i.e., spun) about the central axis A. The tube  32  is then inserted into a cavity  90  of the tool  80 , as illustrated in  FIG. 7 . The tube  32  contacts the walls of the tool  80  that form the cavity  90 . The contact produces friction and heats the tube  32 . In the illustrated example, the tube  32  is heated to a temperature below the melting point of the tube  32  but high enough to make the tube  32  ductile such that continuing force on the tube  32  into the cavity  90  causes the tube  32  to bend inwardly over the extended portion  84  to form the inlet tube portion  34 . As the tube  32  is further inserted into the cavity  90  and inwardly bent over the extended portion  84 , the tube  32  contacts the lip  86 . The lip  86  stops further advancement of the tube  32  into the cavity  90 .  
         [0033]     In one example, the tube  32  is made of a metal or metal alloy. The mechanical force of bending the tube  32  onto the extended portion  84  mechanically forms a thickened neck  92  between the inlet tube portion  34  and the tube  32 .  
         [0034]     Although a preferred embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.