Abstract:
A scroll compressor incorporates a vapor injection system where only one vapor injection port is utilized. The single vapor injection port injects refrigerant vapor into two of the initially formed enclosed spaces. The scrolls of the scroll compressor are designed with asymmetric wraps where the non-orbiting scroll wrap extends angularly further than the orbiting scroll wrap.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to scroll type machines. More particularly, the present invention relates to scroll compressors incorporating a vapor injection system which utilizes a single large port extending through a scroll member.  
         BACKGROUND AND SUMMARY OF THE INVENTION  
         [0002]    Refrigeration and air conditioning systems generally include a compressor, a condenser, an expansion valve or equivalent, and an evaporator. These components are coupled in sequence in a continuous flow path. A working fluid flows through the system and alternates between a liquid phase and a vapor or gaseous phase.  
           [0003]    A variety of compressor types have been used in refrigeration systems, including but not limited to reciprocating compressors, screw compressors and rotary compressors. Rotary compressors can both include the vane type compressors as well as the scroll machines. Scroll machines are constructed using two scroll members with each scroll member having an end plate and a spiral wrap. The spiral wraps are arranged in an opposing manner with the two spiral wraps being interfitted. The scroll members are mounted so that they may engage in relative orbiting motion with respect to each other. During this orbiting movement, the spiral wraps define a successive series of enclosed spaces, each of which progressively decreases in size as it moves inwardly from a radially outer position at a relatively low suction pressure to a central position at a relatively high pressure. The compressed gas exits from the enclosed space at the central position through a discharge passage formed through the end plate of one of the scroll members.  
           [0004]    Refrigeration systems are now incorporating vapor injection systems where a portion of the refrigerant in gaseous form is injected into the enclosed spaces at a pressure which is intermediate the low suction pressure and the relatively high pressure or what is termed discharge pressure. This gaseous refrigerant is injected into the enclosed spaces through injection ports extending through one of the two scroll members. The injection of this gaseous refrigerant has the effect of increasing both system capacity and the efficiency of the compressor. In systems where vapor injection is incorporated to achieve maximum capacity increase, the development engineer attempts to provide a system which will maximize the amount of refrigerant gas that is injected into the enclosed pocket. By maximizing the amount of refrigerant gas that is injected, the system capacity and the efficiency of the compressor are maximized.  
           [0005]    When developing the vapor injection system, the development engineer must ensure that the intermediate pressurized vapor that is being injected is not allowed to migrate into the suction chamber of the compressor. If the intermediate pressurized vapor does migrate into the suction area, the capacity of the compressor will actually decrease. Thus, vapor injection ports are typically placed at a location where they do not communicate with an enclosed space until the enclosed space has been sealed.  
           [0006]    There have been attempts to locate the vapor injection ports at a position where they open just prior to the sealing of the enclosed space. The theory is that the enclosed space will be sealed prior to any of the intermediate pressurized vapor migrating to the suction chamber. While these systems have increased the amount of refrigerant vapor that is injected, the increase in the amount of refrigerant vapor that is injected is less than an optimal amount.  
           [0007]    Thus, the continued development of vapor injection systems is directed towards increasing the amount of intermediate pressurized vapor that can be injected into the enclosed spaces.  
           [0008]    The present invention provides the art with an injection system which utilizes a single large injection port and which injects intermediate pressurized vapor refrigerant into two different enclosed pockets of a scroll compressor having asymmetric scroll wraps. The single large injection port allows for an increased amount of the vapor to be injected into both of the enclosed spaces without the possibility of the injected vapor migrating to the suction area of the compressor.  
           [0009]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0011]    [0011]FIG. 1 is a vertical cross-section of a scroll compressor incorporating the unique vapor injection system in accordance with the present invention;  
         [0012]    [0012]FIG. 2 is a horizontal sectional view of the scroll compressor of the present invention taken just below the partition in FIG. 1;  
         [0013]    [0013]FIG. 3 is a plan view of the non-orbiting scroll of the present invention viewed from the vane side of the non-orbiting scroll;  
         [0014]    [0014]FIG. 4 is a plan view of the scroll members positioned at the point of initially sealing off the first enclosed space;  
         [0015]    [0015]FIG. 5 is a plan view of the scroll members positioned at the point of initially sealing off the second enclosed space;  
         [0016]    [0016]FIG. 6 is a plan view of the scroll members positioned at the point where the vapor injection port is open to two enclosed spaces; and  
         [0017]    [0017]FIG. 7 is a plan view of an orbiting scroll in accordance with another embodiment of the present invention viewed from the vane side of the orbiting scroll.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0019]    Referring now to the drawings in which like reference numerals designate like or corresponding parts throughout the several views, there is shown in FIG. 1, a scroll compressor which incorporates the unique vapor injection system in accordance with the present invention and which is designated generally by the reference numeral  10 . The following description of the preferred embodiment is merely exemplary in nature and is no way intended to limit the invention, its application or its uses.  
         [0020]    Scroll compressor  10  comprises a generally cylindrical hermetic shell  12  having welded at the upper end thereof a cap  14  and at the lower end thereof a base  16  having a plurality of mounting feet (not shown) integrally formed therewith. Cap  14  is provided with a refrigerant discharge fitting  18  which may have the usual discharge valve therein (not shown). Other major elements affixed to shell  12  include a transversely extending partition  20  which is welded about its periphery at the same point cap  14  is welded to shell  12 , an inlet fitting  22 , a main bearing housing  24  which is suitably secured to shell  12  and a lower bearing housing  26  having a plurality of radially outwardly extending legs each of which is suitably secured to shell  12 . A motor stator  28  which is generally square in cross-section but with the corners rounded off is press fit into shell  12 . The flats between the rounded corners on motor stator  28  provide passageways between motor stator  28  and shell  12  which facilitate the return flow of the lubricant from the top of shell  12  to its bottom.  
         [0021]    A drive shaft or crankshaft  30  having an eccentric crank pin  32  at the upper end thereof is rotatably journaled in a bearing  34  in main bearing housing  24  and in a bearing  36  in lower bearing housing  26 . Crankshaft  30  has at the lower end thereof a relatively large diameter concentric bore  38  which communicates with a radially outwardly located smaller diameter bore  40  extending upwardly therefrom to the top of crankshaft  30 . Disposed within bore  38  is a stirrer  42 . The lower portion of the interior shell  12  is filled with lubricating oil and bores  38  and  40  act as a pump to pump the lubricating oil up crankshaft  30  and ultimately to all of the various portions of compressor  10  which require lubrication.  
         [0022]    Crankshaft  30  is relatively driven by an electric motor which includes motor stator  28  having motor windings  44  passing therethrough and a motor rotor  46  press fitted onto crankshaft  30  and having upper and lower counterweights  48  and  50 , respectively. A motor protector  52 , of the usual type, is provided in close proximity to motor windings  44  so that if the motor exceeds its normal temperature range, motor protector  52  will de-energize the motor.  
         [0023]    The upper surface of main bearing housing  24  is provided with an annular flat thrust bearing surfaces  54  on which is disposed an orbiting scroll member  56 . Scroll member  56  comprises an end plate  58  having the usual spiral valve or wrap  60  on the upper surface thereof and an annular flat thrust surface  62  on the lower surface thereof. Projecting downwardly from the lower surface is a cylindrical hub  64  having a journal bearing  66  therein and in which is rotatively disposed a drive bushing  68  having an inner bore within which crank pin  32  is drivingly disposed. Crank pin  32  has a flat on one surface (not shown) which drivingly engages a flat surface in a portion of the inner bore of drive bushing  68  to provide a radially compliant drive arrangement such as shown in assignee&#39;s U.S. Pat. No. 4,877,382, the disclosure of which is incorporated herein by reference.  
         [0024]    Wrap  60  meshes with a non-orbiting scroll wrap  72  forming part of a non-orbiting scroll member  74 . During orbital movement of orbiting scroll member  56  with respect to non-orbiting scroll member  74  creates moving pockets of fluid which are compressed as the pocket moves from a radially outer position to a central position of scroll members  56  and  74 . Non-orbiting scroll member  74  is mounted to main bearing housing  24  in any desired manner which will provide limited axial movement of non-orbiting scroll member  74 . The specific manner of such mounting is not critical to the present invention.  
         [0025]    Non-orbiting scroll member  74  has a centrally disposed discharge port  76  which is in fluid communication via an opening  78  in partition  20  with a discharge muffler  80  defined by cap  14  and partition  20 . Fluid compressed by the moving pockets between scroll wraps  60  and  72  discharges into discharge muffler  80  through port  76  and opening  78 . Non-orbiting scroll member  74  has in the upper surface thereof an annular recess  82  having parallel coaxial sidewalls within which is sealing disposed for relative axial movement an annular seal assembly  84  which serves to isolate the bottom of recess  82  so that it can be placed in fluid communication with a source of intermediate fluid pressure by means of a passageway  86 . Non-orbiting scroll member  74  is thus axially biased against orbiting scroll member  56  by the forces created by discharge pressure acting on the central portion of non-orbiting scroll member  74  and the forces created by intermediate fluid pressure acting on the bottom of recess  82 . This axial pressure biasing, as well as the various techniques for supporting non-orbiting scroll member  74  for limited axial movement, are disclosed in much greater detail in assignee&#39;s aforementioned U.S. Pat. No. 4,877,382.  
         [0026]    Relative rotation of scroll members  56  and  74  is prevented by the usual Oldham Coupling  88  having a pair of key slidably disposed in diametrically opposing slots in non-orbiting scroll member  74  and a second pair of keys slidably disposed in diametrically opposed slots in orbiting scroll member  56 .  
         [0027]    Compressor  10  is preferably of the “low side” type in which suction gas entering shell  12  is allowed, in part, to assist in cooling the motor. So long as there is an adequate flow of returning suction gas, the motor will remain within the desired temperature limits. When this flow ceases, however, the loss of cooling will cause motor protector  52  to trip and shut compressor  10  down.  
         [0028]    The scroll compressor, as thus broadly described, is either known in the art or it is the subject matter of other pending applications for patent by Applicant&#39;s assignee. The details of construction which incorporate the principles of the present invention are those which deal with a unique vapor injection system identified generally by reference numeral  100 . Vapor injection system  100  is used to inject vapor or gaseous refrigerant for increasing the capacity and efficiency of compressor  10 .  
         [0029]    Referring now to FIGS.  1 - 3 , vapor injection system  100  comprises a vapor injection passage  102  extending through an end plate  88  of non-orbiting scroll member  74 , a single vapor injection port  104  opening into the enclosed fluid pockets, a connecting tube  106 , a fluid injection port  108  extending through shell  12  and a vapor injection fitting  110  secured to the outside of shell  12 .  
         [0030]    Vapor injection passage  102  is a cross drill feed hole which extends generally horizontal through non-orbiting scroll member  74  from a position on the exterior of non-orbiting scroll member  74  to a position where it communicates with vapor injection port  104 . Vapor injection port  104  extends generally vertically from passage  102  through non-orbiting scroll member  74  to open into the enclosed spaces or pockets formed by wraps  60  and  72  as detailed below. Connecting tube  106  extends from vapor injection passage  102  to fluid injection port  108  where it extends through fluid injection port  108  to be sealingly secured to vapor injection fitting  110 . While not shown, the source of the intermediate pressurized refrigerant vapor from a refrigeration system (not shown) is in communication with vapor injection fitting  110  to provide the refrigerant vapor for injecting.  
         [0031]    Referring now to FIGS. 4 and 5, the positioning of vapor injection port  104  is illustrated in relation to scroll wraps  60  and  72 . As can be seen in FIGS. 4 and 5, scroll wraps  60  and  72  as asymmetrically designed. Non-orbiting scroll wrap  72  extends an additional angular amount to provide the asymmetrical profile. In the preferred embodiment, non-orbiting scroll wrap  72  extends  1700  further than orbiting scroll wrap  60 . The asymmetrical profile of scroll wraps  60  and  72  causes the two fluid pockets created by wraps  60  and  72  to be initially sealed off at different positions of the orbiting motion of orbiting scroll member  56 . FIG. 4 illustrates the initial sealing point of an enclosed space  120  which is sealed when an outer surface  122  of orbiting scroll wrap  60  engages an inner surface  124  of non-orbiting scroll wrap  72 . Just prior to the time of sealing enclosed space  120 , vapor injection port  104  is sealed off or closed by orbiting scroll wrap  60  as shown in FIG. 4. This ensures that there will not be any intermediate pressurized refrigerant vapor that is allowed to migrate to the suction chamber of compressor  10 . Simultaneous with the sealing of enclosed space  120  by surfaces  122  and  124 , orbiting scroll wrap  60  begins to uncover or open vapor injection port  104  to begin the injection of refrigerant vapor into enclosed space  120 . While FIG. 4 is illustrated with vapor injection port  104  opening simultaneous with the sealing of enclosed space  120 , it is within the scope of the present invention to open vapor injection port  104  prior to or subsequent to the sealing of enclosed space  120  if desired.  
         [0032]    [0032]FIG. 5 illustrates the initial sealing point of an enclosed space  130  which is sealed when an inner surface  132  of orbiting scroll wrap  60  engages an outer surface  134  of non-orbiting scroll wrap  72 . Just prior to the time of sealing enclosed space  130 , vapor injection port  104  is sealed off or closed by orbiting scroll wrap  60  as shown in FIG. 5. This ensures that there will not be any intermediate pressurized refrigerant vapor that is allowed to migrate to the suction chamber of compressor  10 . Simultaneous with the sealing of enclosed space  130  by surfaces  132  and  134 , orbiting scroll wrap  60  begins to uncover or open vapor injection port  104  to begin the injection of refrigerant vapor into enclosed space  130 . While FIG. 5 is illustrated with vapor injection port  104  opening simultaneous with the sealing of enclosed space  130 , it is within the scope of the present invention to open vapor injection port  104  prior to or subsequent to the sealing of enclosed space  130  if desired.  
         [0033]    As can be seen in FIG. 6, the size of vapor injection port  104  is significantly larger than the width of orbiting scroll wrap  60 . This means that during a portion of the cycle for orbiting scroll  56 , vapor injection port  104  will be open to both enclosed space  120  and enclosed space  130 . This does not present a problem to the operation and function of vapor injection system  100  because the pressure of refrigerant vapor at vapor injection port  104  is always larger than the pressure of refrigerant gas in enclosed spaces  120  and  130 . The increased size for vapor injection port  104  allows for the unique ability of a single port being able to open to both enclosed spaces  120  and  130  simultaneous to the sealing of the respective enclosed space. In addition, the increased size of vapor injection port  104  allows for the injection of an increased amount of intermediate pressurized gas to increase the capacity and efficiency of compressor  10 .  
         [0034]    Referring now to FIG. 7, an orbiting scroll member  56 ′ is illustrated. Orbiting scroll member  56 ′ is the same as orbiting scroll  56  except that vapor injection passage  102  and vapor injection port  104  are located in orbiting scroll  56 ′ instead of non-orbiting scroll member  74 . Vapor injection passage  102  which extends through orbiting scroll member  56 ′ is in communication with the exterior of shell  12  by utilizing connecting tube  106  or by other means known well in the art. Other methods of providing communication for vapor injection passage  102  and vapor injection port  104  are shown in Assignee&#39;s co-pending patent application Ser. No. 09/639,004 the disclosure of which is incorporated herein by reference.  
         [0035]    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.