Patent Publication Number: US-9850903-B2

Title: Capacity modulated scroll compressor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/089,677, filed on Dec. 9, 2014. The entire disclosure of the above application is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to scroll compressors, and, specifically, scroll compressors having capacity modulated systems. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     Scroll compressors include a variety of capacity modulation mechanisms to vary operating capacity of a compressor. Capacity modulation may be used to operate a compressor at full load or part load conditions. Requirement of full or part load variation depends on seasonal variation, occupants present in a conditioned space, and/or load requirement for a refrigeration unit. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     A system includes a compressor. The compressor may further include an orbiting scroll member having a first end plate and a first spiral wrap. A non-orbiting scroll member has a second end plate and a second spiral wrap, and the second spiral wrap forms a meshing engagement with the first spiral wrap to create a plurality of compression chambers between a suction port and a discharge port of the orbiting scroll member and the non-orbiting scroll member. A first port is in communication with a first of the plurality of compression chambers and selectively injects an injection fluid into the first of the plurality of compression chambers to increase a compressor capacity and selectively leaks a first compressed fluid from the first of the plurality of compression chambers to reduce the compressor capacity. A second port in communication with a second of the plurality of compression chambers and selectively leaking a second compressed fluid from the second of the plurality of compression chambers to reduce a compressor capacity. 
     The system may further include a controller controlling a plurality of valves that control the selective injection of the injection fluid and selectively leaking of the first and second compressed fluids. 
     The system may further include a second port that is not leaking the second compressed fluid when the first port injects the injected fluid into the first of the plurality of compression chambers. 
     The system may further include a second port that is one of leaking the second compressed fluid or not leaking the second compressed fluid when the first port leaks the first compressed fluid from the first of the plurality of compression chambers to reduce the compressor capacity. 
     The system may further include a second port and a first port that operate to reduce compressor capacity. 
     The system may further include a first passage in communication with the first port and a first fitting to transport fluid between the first of the at least one compression chamber and the first fitting. 
     The system may further include a first conduit in communication with the first fitting and a heat exchanger, wherein the first conduit transports compressed fluid from the heat exchanger to the first fitting. 
     The system may further include an expansion valve positioned within the first conduit to permit or prevent communication between the heat exchanger and the first fitting. 
     The system may further include a second conduit in communication with the first fitting and a suction pressure region, wherein the second conduit transports fluid from the first fitting to the suction pressure region. 
     The system may further include a solenoid valve positioned within the second conduit to permit or prevent communication between the suction pressure region and the first fitting. 
     The system may further include a second passage in communication with the second port and a second fitting to leak the second compressed fluid from the second of the at least one compression chamber. 
     The system may further include a third conduit in communication with the second fitting and a suction pressure region, wherein the third conduit transports fluid from the second fitting to the suction pressure region. 
     The system may further include a second solenoid valve positioned within the third conduit to permit or prevent communication between the second fitting and the suction pressure region. 
     The system may further include a first passage in communication with the first port and a first fitting to transport fluid between the first of the plurality of compression chambers and the first fitting. A first conduit may be in communication with the first fitting and a heat exchanger, wherein the first conduit transports compressed fluid from the heat exchanger to the first fitting. A second conduit may be in communication with the first fitting and a suction pressure region, wherein the second conduit transports fluid from the first fitting to the suction pressure region. A third solenoid valve may selectively permit or prevent flow between the first conduit and the suction pressure region, between the second conduit and the suction pressure region, or both the first and second conduits and the suction pressure region. 
     The system may further include at least one of a first port and a second port being a single larger port or a plurality of small ports grouped together. 
     The system may further include a first port is located radially outward relative to a second port. 
     Another compressor may include a first scroll member having a first end plate and a first spiral wrap. A second scroll member includes a second end plate and a second spiral wrap, wherein the second spiral wrap forms a meshing engagement with the first spiral wrap to create a plurality of compression chambers between the first scroll member and the second scroll member. A first port injects a fluid into a first of the plurality of compression chambers to increase a compressor capacity or leaks compressed fluid from the first of the plurality of compression chambers to reduce the compressor capacity. A second port leaks compressed fluid from a second of the plurality of compression chambers to reduce the compressor capacity. 
     The compressor may further include a first port that both injects the fluid into the first of the plurality of compression chambers to increase the compressor capacity and leaks compressed fluid from the first of the plurality of compression chambers to reduce the compressor capacity. 
     The compressor may further include a first port that is a vapor injection port in communication with the first of the plurality of compression chambers and injects the fluid into the first of the plurality of compression chambers to increase the compressor capacity, and a second port that is a bypass port in communication with the second of the plurality of compression chambers and leaks compressed fluid from the second of the plurality of compression chambers to reduce the compressor capacity. 
     The compressor may further include a first port that is positioned radially outward relative to a second port. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a perspective view of a compressor according the present disclosure; 
         FIG. 2  is a detail perspective view of the compressor of  FIG. 1 ; 
         FIG. 3  is an exploded view of the compressor of  FIG. 1 ; 
         FIG. 4  is a section view of the compressor of  FIG. 1  illustrating the compressor in an operational state; 
         FIG. 5  is a section view of the compressor of  FIG. 1  showing the compressor in a different operational state; 
         FIG. 6  is a section view of another compressor in an operational state; 
         FIG. 7  is a section view of the compressor in  FIG. 6  in a different operational state; 
         FIG. 8  is another section view of the compressor of  FIG. 1 ; 
         FIG. 9  is schematic view of a refrigeration system incorporating the compressor of  FIG. 1 ; 
         FIG. 10  is a schematic view of another refrigeration system incorporating the compressor of  FIG. 1 ; and 
         FIG. 11  is a schematic view of another refrigeration system incorporating the compressor of  FIG. 1 . 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. 
     Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
     A capacity modulation system according to the present disclosure allows for several levels of capacity reduction in a compressor. The capacity modulation system utilizes an economized vapor injection (EVI) port and a bypass port to either inject vapor fluid into the compressor to increase capacity, and/or leak compressed fluid from the compressor to reduce capacity. The positions of the EVI and bypass ports within the compressor and the areas of the EVI and bypass ports determine the amount of capacity increase or reduction that can be achieved. While the capacity modulation system is described and illustrated as modifying the capacity of a scroll compressor, it is understood that the concepts of the capacity modulation system may be applied to other compressors as well. For example only, the concepts of the capacity modulation system may be applied to a screw compressor. 
     With initial reference to  FIGS. 1 and 2 , a compressor  10  may include a hermetic shell assembly  12  housing a compression mechanism  18 . The compression mechanism  18  may be a scroll compressor. The shell assembly  12  provides access to the compression mechanism  18  through a suction port  22 , a discharge port  26 , and a plurality of other ports  30 ,  34 . In the illustrated embodiment of  FIGS. 4-5 , port  30  is an EVI-bypass combination port (referred to hereafter as an EVI port) and port  34  is a bypass port. While port  30  is illustrated and described ad an EVI-bypass combination port and port  34  is illustrated and described as a bypass port, ports  30 ,  34  may be economized vapor injection (EVI) ports, bypass ports, or a combination thereof. 
     With additional reference to  FIG. 3 , the compression mechanism  18  may generally include an orbiting scroll  38  and a fixed, or non-orbiting, scroll  42 . The orbiting scroll  38  may include an end plate  46  having a spiral vane or wrap  50  on the upper surface thereof. The non-orbiting scroll  42  may include an end plate  54  having a spiral wrap  58  on a lower surface thereof which forms a meshing engagement with the wrap  50  of the orbiting scroll  38 , thereby creating a series of pockets, or compression chambers ( FIGS. 4-7 ). An Oldham coupling  60  may be engaged with the orbiting and non-orbiting scrolls  38 ,  42  to prevent relative rotation therebetween. 
     Referring additionally to  FIGS. 4-7 , the scroll wraps  50 ,  58  interfit and surround discharge port  26 . The orbiting scroll  38  orbits relative to the non-orbiting scroll  42  and the scroll wraps  50 ,  58  selectively trap refrigerant in the series of pockets, or compression chambers, which compress the refrigerant toward discharge port  26 . The EVI and/or bypass ports,  30 ,  34  are formed in the non-orbiting scroll  42  to selectively inject an injected fluid into one of the compression chambers or leak a compressed fluid from one of the compression chambers to increase or reduce compressor capacity, as will be described in relation to  FIGS. 9-11 . The EVI and/or bypass ports  30 ,  34  may be a single larger port ( FIGS. 4 and 5 ) or the EVI and bypass ports  30 ,  34  may be a plurality of small ports grouped together (as shown by items  78 ,  82  in  FIGS. 6 and 7 ). 
     An EVI passage  62  provides communication between the EVI port  30  and the exterior of the shell  12 , and a bypass passage  66  provides communication between the bypass port  34  and the exterior of the shell  12 . An EVI fitting  64  is disposed on the exterior of the shell  12  and communicates with the EVI port  30  through the EVI passage  62 . A bypass fitting  68  is disposed on the exterior of the shell  12  and communicates with the bypass port  34  through the bypass passage  66 . Because of the location of the EVI port  30  and bypass port  34  within the non-orbiting scroll  42 , the EVI fitting  64  and bypass fitting  68  may be disposed on approximately opposing sides of the shell  12 . 
     Now referring to  FIG. 4 , the EVI port  30  is uncovered by the orbiting scroll  38  at about the same time that a compression chamber  70  is sealed from a zone  74  that communicates with suction port  22  (e.g., a suction pressure zone.). As shown in  FIG. 5 , as the orbiting scroll  38  continues to move relative to the non-orbiting scroll  42 , bypass port  34  remains partially in communication with compression chamber  70 , but is mostly covered by the orbiting scroll  38 . EVI port  30  moves into communication with compression chamber  76 . 
     Now referring to  FIGS. 6 and 7 , EVI port  30  and bypass port  34  may be series of small ports  78 ,  82 , respectively. By using a series of small ports  78 ,  82 , different variability in compressor capacity can be achieved.  FIG. 6  illustrates the EVI ports  78  are uncovered by the orbiting scroll  38  at about the same time that the compression chamber  70  is sealed from the zone  74  that communicates with suction port  22  (e.g., a suction pressure zone), similar to  FIG. 4 .  FIG. 7  illustrates bypass ports  82  covered by the orbiting scroll  38  as the orbiting scroll  38  continues to move relative to the non-orbiting scroll  42 ; whereas EVI ports  78  move into communication with compression chamber  76 . 
     As shown in  FIG. 8 , EVI passage  62  communicates with EVI port  30 , and bypass passage  66  communicates with bypass port  34 . EVI fitting  64  engages the exterior surface of the shell  12  and communicates between the EVI port  30  and a line  90  external to the compressor  10  ( FIGS. 9-11 ). As illustrated in conjunction with  FIGS. 4-5 , EVI port  30  may be positioned closer to the suction port than the bypass port  34 . This means that the EVI port  30  may be positioned or located radially outward relative to the bypass port  34 . Bypass fitting  68  engages the exterior surface of the shell  12  and communicates between the bypass port  34  and a line  98  external to the compressor  10  ( FIGS. 9-11 ). While lines  90  and  98  are referred to as lines throughout the spec, lines  90  and  98  may also be referred to as fluid conduits. 
     As illustrated in conjunction with  FIGS. 4-5 , EVI port  30  may be positioned closer to the zone  74  communicating with suction port  22  than the bypass port  34 . By moving the bypass port  34  closer to the discharge port  26 , capacity is further reduced because a portion of the wraps  50 ,  58  compressing the fluid are removed. The location of the bypass port  34  is optimized by taking into consideration the axial balance of the scrolls  38 ,  42  and the desired capacity reduction. The closer the bypass port  34  is positioned to the discharge port  26  and the further the bypass port  34  is positioned from the EVI port  30 , the more capacity reduction is achieved. However, the scroll  38 ,  42  instability also increases as the bypass port  34  is positioned closer to the discharge port  26 , because a bleed hole  92  ( FIG. 6 ) for a biasing chamber  96  ( FIG. 3 ) must apply enough force against the non-orbiting scroll  42  to maintain sealing between the compression pockets. 
     In some embodiments, only one port is necessary for both EVI functions and bypass functions. In the embodiments illustrated in the Figures, the EVI port  30  is used for both EVI functions and bypass functions, and the bypass port  34  is used for bypass functions. Because the EVI port  30  and the bypass port  34  do not communicate in reducing the capacity of the compressor  10 , there is no significant penalty in full load conditions. Further, the capacity reduction is limited by the size of the port  30 ,  34  and therefore, two ports enable a larger capacity reduction. Further, the capacity reduction of the compressor  10  is limited by the size of the port  30 ,  34  and therefore two ports enable a larger capacity reduction than a single port. 
     Now referring to  FIGS. 9-11 , several embodiments for capacity reduction in the compressor  10  are illustrated. During operation, multiple levels (for example, four) of capacity may be achieved. The compressor  10  is a portion of a refrigerant system  100 ,  200 ,  300  also having a condenser  104 , a heat exchanger (HX), or flash tank,  108 , and an evaporator  112 . A discharge outlet  114  is in communication with a line  116  leading to the condenser  104 . The condenser  104  communicates with the heat exchanger  108  through a line  120 . Beyond the heat exchanger  108 , fluid flows through a line  124  and a valve  128  in communication with the evaporator  112 . The evaporator  112  is in communication with the suction port  22  through a line  132 . 
     A controller  134  may operate to control the opening and closing of a plurality of valves, as further described below. While only a single controller  134  is illustrated and described as controlling each of the valves, one or more of the plurality of valves may be controlled by one or more additional controllers for selectively opening and closing the valves to provide liquid fluid injection, vapor fluid injection and/or leak compressed fluid, thereby allowing capacity modulation of the compressor. 
     Referring specifically to  FIG. 9 , when operating at an economized capacity, fluid may exit the compressor through the discharge outlet  114  into line  116 . After passing through the condenser  104 , the fluid may enter a line  136  containing a valve  140 . Valve  140  may be an expansion device, such as an electronic expansion valve, a thermostatic expansion valve, a capillary tube, or a float valve. Valve  140  may vary in the amount that it is open, such that it variably controls the amount of fluid passing through. The fluid continues in line  136  and passes through heat exchanger  108  and into line  90 . Line  90  may further contain an optional solenoid valve  144 . The fluid is injected back into compressor  10  through EVI port  30  to increase the compression of the fluid within the various compression pockets of wraps  50 ,  58 . In any emobdiment the injected fluid that is injected back into compressor  10  through EVI port  30  may be a vapor fluid or a liquid fluid. 
     Valve  148  along line  98  between bypass port  34  and line  132  may be selectively closed to prevent reduction in capacity. Alternatively, valve  148  may be located inside the compressor  10  to thereby selectively leak refrigerant from the bypass port  34  into the suction pressure zone. With this alternative, the bypass fitting  68  and line  98  are not used because the refrigerant will leak directly back to the suction pressure zone from the bypass port  34  through the bypass passage  66 . By injecting fluid into compressor  10  through EVI port  30 , capacity of the compressor  10  may be increased over the capacity of the compressor  10  without the fluid injection. 
     When operating at a full capacity, valves  140 ,  144 , and  148  may be closed such that the fluid follows a path as previously described from the discharge outlet  114 , to the condenser  104 , to the heat exchanger  108 , to the evaporator  112 , and back through the suction port  22 . 
     When operating at a first lower level of capacity, valves  140  and  144  may be selectively closed while valve  148  may be selectively opened to utilize the bypass port  34 . Valve  148  may be a solenoid valve for opening and closing line  98  communicating with bypass port  34 . During operation, a portion of partially compressed fluid exits the compressor  10  through the bypass port  34  before reaching full compression and discharge port  26 . The amount of capacity reduction is dependent on the amount of partially compressed fluid exiting the compressor  10 . The amount of partially compressed fluid exiting the compressor  10  is dependent on the area and location of the bypass port  34 . The partially compressed fluid exits the bypass port  34  into line  98 . The partially compressed fluid passes through valve  148  and into line  132  to reenter the suction port  22 . 
     As previously mentioned, controller  134  may control the opening and closing of valves  128 ,  140 ,  144  and  148  to selectively open and close communication with the EVI port  30  and the bypass port  34 . In other aspects, one or more of valves  128 ,  140 ,  144 , and  148  may be controlled by one or more additional controllers. 
     Now referring specifically to  FIG. 10 , system  200  may contain many of the same features as system  100  including, but not limited to, condenser  104 , heat exchanger  108 , evaporator  112 , valves  128 , 140 ,  144 ,  148 , and lines  90 ,  98 ,  116 ,  120 ,  124 ,  132 , and  136 . Line  204  and valve  208  may communicate between line  90 , thus EVI port  30 , and line  132 , thus suction port  22 . 
     When operating at an economized capacity, fluid may exit the compressor through the discharge outlet  114  into line  116 . After passing through the condenser  104 , the fluid may enter line  136  containing valve  140 . The fluid continues in line  136  and passes through heat exchanger  108  and into line  90 . Line  90  may further contain optional valve  144 . The fluid is injected back into compressor  10  through EVI port  30  to increase the compression of the fluid within the various compression pockets of wraps  50 ,  58 . The injected fluid that is injected back into compressor  10  through EVI port  30  may be a vapor fluid, a liquid fluid or a combination vapor-liquid fluid (e.g. wet vapor). 
     Valve  148  along line  98  and valve  208  along line  204  may be selectively closed to prevent reduction in capacity. By injecting fluid into compressor  10  through EVI port  30 , capacity of the compressor  10  may be increased over the capacity of the compressor  10 . 
     When operating at a full capacity, valves  140 ,  144 ,  148 , and  208  may be selectively closed such that the fluid follows a path as previously described from the discharge outlet  114 , to the condenser  104 , to the heat exchanger  108 , to the evaporator  112 , and back through the suction port  22 . 
     When operating at a first lower level of capacity, valves  140 ,  144 , and  148  may be selectively closed while valve  208  may be open. Fluid may pass as stated in full capacity mode. However, the portion of the compression pockets of wraps  50 ,  58  that are in communication with EVI port  30 ,  78  may now be in communication with line  132 , thereby creating a leak path in the compression pockets to a suction pressure zone via line  90 , line  204 , and valve  208 . Thus, by creating a leak path from compressor  10  through EVI port  30 , a first compressed fluid may be leaked from a compression pocket to the suction pressure zone such that capacity of the compressor  10  may be reduced because the overall compression of the fluid within the compression chambers of the wraps  50 ,  58  is reduced. 
     When operating at a second lower level of capacity, valves  140  and  144  may be closed while valves  148  and  208  may be open to utilize the EVI port  30  and the bypass port  34 . The process through the EVI port  30  may operate the same as previously described in the first lower level of capacity for system  200 . Additional capacity reduction is provided through use of the bypass port  34 , where a portion of a second compressed fluid exits the compressor  10  through the bypass port  34  before reaching full compression and discharge port  26 . The amount of additional capacity reduction is dependent upon the amount of the second compressed fluid exiting another compression pocket; thus the amount of the second compressed fluid exiting the compressor  10  is dependent on the area and location of the bypass port  34 . The second compressed fluid exits the bypass port  34  into line  98 . The fluid passes through valve  148  and into line  132  to reenter the suction port  22 . 
     A difference between the first compressed fluid that is leaked through the EVI port  30  and the second compressed fluid that exits through the bypass port  34  is directly related to the first and second compressed fluids being leaked at different points in the compression process. The EVI port  30  being located radially outward of the bypass port  34  causes the first compressed fluid to be less compressed than the second compressed fluid. Therefore the leaking of the first compressed fluid from the EVI port  30  creates less reduction in capacity than the leaking of the second compressed fluid from the bypass port  34 , thus achieving different levels of capacity. 
     As previously mentioned, controller  134  selectively controls the opening and closing of valves  128 ,  140 ,  144 ,  148 , and  208  to selectively open and close communication with the EVI port  30  and the bypass port  34 . In other aspects, one or more of valves  128 ,  140 ,  144 ,  148 , and  208  may be controlled by one or more additional controllers. 
     Now referring specifically to  FIG. 11 , system  300  may contain many of the same features as systems  100  and  200  including, but not limited to, condenser  104 , heat exchanger  108 , evaporator  112 , valves  128 , 140 ,  144 , and lines  90 ,  98 ,  116 ,  120 ,  124 ,  132 ,  136 , and  204 . Valve  304  may selectively communicate between lines  90 ,  98 ,  132 , and  204 , thus EVI port  30 , bypass port  34 , and suction port  22 . Valve  304  may be a three-way valve having a first position which restricts communication between all of line  90 , line  98 , and line  132 , a second position allowing communication between line  90  and line  132  while blocking communication between line  98  and  132 , and a third position allowing line  90  and line  98  to communicate with line  132 . Thus, valve  304  selectively allows or restricts communication between EVI port  30  and suction port  22  and bypass port  34  and suction port  22 . 
     When operating at an economized capacity, fluid may selectively exit the compressor through the discharge outlet  114  into line  116 . After passing through the condenser  104 , the fluid may enter line  136  containing valve  140 . The fluid continues in line  136  and passes through heat exchanger  108  and into line  90 . Line  90  may further contain optional valve  144 . The fluid is selectively injected back into compressor  10  through EVI port  30  to increase the compression of the fluid within the various compression pockets of wraps  50 ,  58 . The injected fluid that is injected back into compressor  10  through EVI port  30  may be a vapor fluid, a liquid fluid or a combination vapor-liquid fluid (e.g. wet vapor). 
     Valve  304  along line  204  may be closed to prevent reduction in capacity. By injecting fluid into compressor  10  through EVI port  30 , capacity of the compressor  10  may be increased over the capacity of the compressor  10 . 
     When operating at a full capacity, valves  140 ,  144 , and  304  may be closed such that the fluid follows a path as previously described from the discharge outlet  114 , to the condenser  104 , to the heat exchanger  108 , to the evaporator  112 , and back through the suction port  22 . 
     When operating at a first lower level of capacity, valves  140  and  144  may be closed while valve  304  may allow communication between lines  204 / 90  and line  132 . However, valve  304  may prevent communication with line  98 . Fluid may pass as stated in the full capacity mode. However, the portion of the compression pockets of wraps  50 ,  58  that are in communication with EVI port  30 ,  78  may now be in communication with line  132 , thereby creating a leak path in the compression pockets to a suction pressure zone via line  90 , line  204 , and valve  304 . Thus, by creating a leak path from compressor  10  through EVI port  30 , a first compressed fluid may be leaked from the compression pockets to the suction pressure zone such that capacity of the compressor  10  may be reduced because the overall compression of the fluid is reduced. 
     When operating at a second lower level of capacity, valves  140  and  144  may be closed while valve  304  may allow communication between line  98  and lines  204 / 132  and line  90  and lines  204 / 132 . Capacity reduction is provided through use of the bypass port  34  and the EVI port  30 , where a portion of a second compressed fluid exits the compressor  10  through the bypass port  34  and a portion of the first compressed fluid exits the compressor  10  through the EVI port  30  before reaching full compression and discharge port  26 . The amount of first and second compressed fluids exiting the compressor  10  is dependent on the area and location of the bypass port  34 . The second compressed fluid exits the bypass port  34  into line  98 . The fluid passes through valve  304  and into line  132  to reenter the suction port  22 . 
     As previously stated, a difference between the first compressed fluid that is leaked through the EVI port  30  and the second compressed fluid that exits through the bypass port  34  is directly related to the first and second compressed fluids being leaked at different points in the compression process. The EVI port  30  being located radially outward of the bypass port  34  causes the first compressed fluid to be less compressed than the second compressed fluid. Therefore the leaking of the first compressed fluid from the EVI port  30  creates less reduction in capacity than the leaking of the second compressed fluid from the bypass port  34 , thus achieving different levels of capacity. 
     As previously mentioned, controller  134  may control the opening and closing of valves  128 ,  140 ,  144 , and  304  to selectively open and close communication with the EVI port  30  and the bypass port  34 . In other aspects, one or more of valves  128 ,  140 ,  144 , and  304  may be controlled by one or more additional controllers. 
     In general, the present disclosure achieves benefits by utilizing a dual purpose EVI-bypass port and a secondary bypass port to achieve both economized and multiple bypass operations. The use of multiple EVI and/or bypass ports allow several levels of capacity reduction without the penalties associated with economized and bypass operation through a single port. In this way, the present disclosure improves upon the prior art. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.