Patent Publication Number: US-2012039735-A1

Title: Variable capacity rotary compressor and air conditioning system having the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the priority benefit of Korean Patent Application No. 10-2010-0078318, filed on Aug. 13, 2010 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     Embodiments relate to a variable capacity rotary compressor having a variable refrigerant compression capacity and an air conditioning system having the same. 
     2. Description of the Related Art 
     A rotary compressor is used in an air conditioning system to compress refrigerant. Recently, a variable capacity rotary compressor, the capacity of which is variable to efficiently deal with various refrigeration loads, has been widely used. 
     A conventional variable capacity rotary compressor includes two cylinders or compressing chambers, which are mechanically controlled such that one of the cylinders always performs compression of refrigerant and the other cylinder selectively performs compression of refrigerant only as necessary. 
     In this case, selectively performing compression of refrigerant only as necessary may require control of the pressure of refrigerant introduced into the cylinder. To this end, a variety of valves and flow-path mechanisms have been used, leading to a complicated configuration. 
     Using these various additional valves and flow-path mechanisms to control the pressure of refrigerant may deteriorate performance of the compressor and also, may require changes in connection configurations between the compressor and the valves and flow-path mechanisms. Therefore, there is a need for a configuration to control the pressure of refrigerant in a more simplified manner. 
     SUMMARY 
     Therefore, it is one aspect to provide a rotary compressor, the capacity of which is variable with a simplified configuration, and an air conditioning system having the rotary compressor. 
     It is another aspect to provide a rotary compressor to enable efficient compression of refrigerant and an air conditioning system having the rotary compressor. 
     Additional aspects of the invention will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the invention. 
     In accordance with one aspect, a compressor, used in an air conditioning system including a condenser, a compressor, an evaporator and an expansion valve, includes a housing, a compressing chamber defined in the housing, and a vane to be moved forward or rearward in a radial direction of the compressing chamber, wherein the vane is moved forward or rearward depending on an opening rate of the expansion valve. 
     A pulling member may be placed between an inner circumferential surface of the housing and a rear end of the vane and serves to force the vane rearward. 
     The pulling member may be a magnet. 
     The pulling member may be an elastic member. 
     The compressor may further include a bypass valve placed in parallel to the expansion valve to bypass refrigerant to be introduced into the expansion valve. 
     The vane may be divided into at least two individually movable vanes. 
     The pulling member may be placed at the rear of one of the at least two divided vanes. 
     In accordance with another aspect, a compressor, used in an air conditioning system including a condenser, a compressor, an evaporator and an expansion valve, includes a housing, a first compressing chamber and a second compressing chamber defined in the housing, a first vane to be moved forward or rearward in a radial direction of the first compressing chamber, and a second vane to be moved forward or rearward in a radial direction of the second compressing chamber, wherein any one of the first vane and the second vane is moved forward or rearward depending on an opening rate of the expansion valve. 
     The first compressing chamber may be located above the second compressing chamber. 
     A pulling member may be placed at the rear of any one of the first vane and the second vane and may serve to force any one of the first vane and the second vane rearward. 
     The pulling member may be a magnet. 
     The pulling member may be an elastic member. 
     The compressor may further include a bypass valve placed in parallel to the expansion valve to bypass refrigerant to be introduced into the expansion valve. 
     Any one of the first vane and the second vane may be divided into at least two individually movable vanes. 
     In accordance with another aspect, a compressor, used in an air conditioning system including a condenser, a compressor, an evaporator and an expansion valve, includes a housing, a low-pressure pipe connected to the housing to enable introduction of relatively low-pressure refrigerant, a high-pressure pipe connected to the housing to enable discharge of relatively high-pressure refrigerant, a first compressing chamber and a second compressing chamber defined in the housing, and a first vane to be moved forward or rearward in a radial direction of the first compressing chamber and a second vane to be moved forward or rearward in a radial direction of the second compressing chamber, wherein any one of the first vane and the second vane is moved forward or rearward depending on a difference between the pressure of refrigerant introduced into the low-pressure pipe and the pressure of refrigerant discharged from the high-pressure pipe. 
     The difference between the pressure of refrigerant introduced into the low-pressure pipe and the pressure of refrigerant discharged from the high-pressure pipe may be adjusted by controlling an opening rate of the expansion valve. 
     The compressor may further include a bypass valve placed in parallel to the expansion valve to bypass refrigerant to be introduced into the expansion valve. 
     A pulling member may be placed at the rear of any one of the first vane and the second vane and may serve to force any one of the first vane and the second vane rearward. 
     Any one of the first vane and the second vane may be divided into at least two individually movable vanes. 
     In accordance with a further aspect, a compressor, used in an air conditioning system including a condenser, a compressor, an evaporator and an expansion valve, includes a housing, a low-pressure pipe connected to the housing to enable introduction of relatively low-pressure refrigerant, a high-pressure pipe connected to the housing to enable discharge of relatively high-pressure refrigerant, a first compressing chamber and a second compressing chamber defined in the housing, and a first vane to be moved forward or rearward in a radial direction of the first compressing chamber and a second vane to be moved forward or rearward in a radial direction of the second compressing chamber, wherein any one of the first vane and the second vane is moved forward or rearward as a difference between the pressure of refrigerant introduced into the low-pressure pipe and the pressure of refrigerant discharged from the high-pressure pipe is adjusted by controlling an opening rate of the expansion valve. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a longitudinal sectional view of a variable capacity rotary compressor according to an embodiment; 
         FIG. 2  is a plan sectional view illustrating a first compressing chamber provided in the variable capacity rotary compressor according to the embodiment; 
         FIG. 3  is a plan sectional view illustrating a second compressing chamber provided in the variable capacity rotary compressor according to the embodiment; 
         FIG. 4  is a diagram illustrating an air conditioning system using a variable capacity rotary compressor according to an embodiment of; 
         FIG. 5  is a diagram illustrating an air conditioning system with an additional bypass valve as compared to  FIG. 4 ; 
         FIG. 6  is an enthalpy-pressure diagram of an air conditioning system according to an embodiment; and 
         FIG. 7  is a sectional view illustrating a dividable vane provided in the variable capacity rotary compressor according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to an exemplary embodiment, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. 
       FIG. 1  is a longitudinal sectional view of a variable capacity rotary compressor according to an embodiment,  FIG. 2  is a plan sectional view illustrating a first compressing chamber provided in the variable capacity rotary compressor according to the embodiment, and  FIG. 3  is a plan sectional view illustrating a second compressing chamber provided in the variable capacity rotary compressor according to the embodiment. 
     As illustrated in  FIG. 1 , the variable capacity rotary compressor  100  according to the embodiment is used to compress refrigerant in an air conditioning system. The variable capacity rotary compressor  100  includes a housing  10  defining an external appearance of the compressor  100 , a drive device  20  placed in the housing  10  to generate rotating power, and a compressing device  30  to compress refrigerant upon receiving power from the drive device  20 . An accumulator  40  is installed around the housing  10 , serves to vaporize liquid-phase refrigerant which has not evaporated in an evaporator (not shown) constituting an air conditioning system, and allows gas-phase refrigerant to be introduced into the compressing device  30 . 
     The drive device  20  includes a cylindrical stator  21  fixed to an inner surface of the housing  10 , a rotator  22  rotatably installed inside the stator  21 , and a rotating shaft  23  having one end fixed to the rotator  22  and the other end installed to the compressing device  30  so as to transmit rotating power generated by the drive device  20  to the compressing device  30 . 
     The compressing device  30 , as illustrated in  FIGS. 2 and 3 , includes a first cylinder  31  and a second cylinder  32  respectively having a first compressing chamber  31   a  and a second compressing chamber  32   a  for compression of refrigerant, a first flange  33  and a second flange  34  configured to close an upper end of the first compressing chamber  31   a  and a lower end of the second compressing chamber  32   a  while rotatably supporting the rotating shaft  23 , and an intermediate plate  35  interposed between the first cylinder  31  and the second cylinder  32  to divide the first compressing chamber  31   a  and the second compressing chamber  32   a  from each other. 
     The first compressing chamber  31   a  and the second compressing chamber  32   a  respectively receive a first roller  36  and a second roller  37 , which compress refrigerant by being eccentrically rotated upon receiving rotating power from the rotating shaft  23 . To allow the first roller  36  and the second roller  37  to be eccentrically rotated in the first compressing chamber  31   a  and the second compressing chamber  32   a , respectively, the rotating shaft  23  includes a first eccentric portion  23   a  and a second eccentric portion  23   b , which are eccentric to a rotation center of the rotating shaft  23 . The first roller  36  is rotatably installed around the first eccentric portion  23   a , and the second roller  37  is rotatably installed around the second eccentric portion  23   b.    
     A discharge pipe  11  is connected to an upper end of the housing  10  to discharge compressed refrigerant from the housing  10 . A first suction pipe  12  and a second suction pipe  13  are connected to lower peripheral positions of the housing  10  to suction refrigerant to be compressed in the first compressing chamber  31   a  and the second compressing chamber  32   a.    
     The first cylinder  31  and the second cylinder  32  are respectively provided with a first suction port  31   b  and a second suction port  32   b , which are connected to the first suction pipe  12  and the second suction pipe  13 , respectively, such that refrigerant having passed through the first suction pipe  12  and the second suction pipe  13  is suctioned into the first compressing chamber  31   a  and the second compressing chamber  32   a.    
     Since the refrigerant discharged through the discharge pipe  11  has a higher pressure than the refrigerant introduced through the first suction pipe  12  and the second suction pipe  13 , the discharge pipe  11  serves as a high-pressure pipe and the first suction pipe  12  and the second suction pipe  13  serve as low-pressure pipes. 
     The first flange  33  and the second flange  34  are provided with a first discharge port  33   a  and a second discharge port  34   a , respectively, to allow the refrigerant compressed in the first compressing chamber  31   a  and the second compressing chamber  32   a  to be discharged into the interior of the housing  10 . 
     A first vane  38  is installed in the first compressing chamber  31   a . The first vane  38  is movable forward or rearward in a radial direction of the first roller  36  and serves to divide the interior of the first compressing chamber  31   a  into a refrigerant compression region and a refrigerant suction region when a tip end of the first vane  38  is supported by the first roller  36 . 
     A second vane  39  is installed in the second compressing chamber  32   a  and is elastically supported by an elastic member  39   a . The second vane  39  is movable forward or rearward in a radial direction of the second roller  37  and serves to divide the interior of the second compressing chamber  32   a  into a refrigerant compression region and a refrigerant suction region when a tip end of the second vane  39  is supported by the second roller  37 . 
     The first cylinder  31  and the second cylinder  32  are provided with a first guide groove  31   c  and a second guide groove  32   c , respectively. The first vane  38  and the second vane  39  are movable forward or rearward in the first guide groove  31   c  and the second guide groove  32   c , respectively. 
     In the variable capacity rotary compressor  100  having the above-described configuration, the capacity of the compressor may vary via forward or rearward movement of the first vane  38 . This will be described hereinafter. 
     Hereinafter, a configuration and method for varying the capacity of the variable capacity rotary compressor  100  according to the embodiment through control of an expansion valve  300  will be described. 
       FIG. 4  is a diagram illustrating an air conditioning system using a variable capacity rotary compressor according to an embodiment,  FIG. 5  is a diagram illustrating an air conditioning system with an additional bypass valve as compared to  FIG. 4 , and  FIG. 6  is an enthalpy-pressure diagram of an air conditioning system according to an embodiment. 
     As illustrated in  FIG. 4 , the air conditioning system according to the embodiment includes the variable capacity rotary compressor  100 , condenser  200 , expansion valve  300 , and evaporator  400 . 
     The condenser  200  serves to condense and liquefy high-temperature and high-pressure gas-phase refrigerant discharged from the rotary compressor  100  into high-temperature and high-pressure liquid-phase refrigerant by transferring heat of the gas-phase refrigerant to peripheral air or cooling water. 
     The expansion valve  300  serves to expand the high-temperature and high-pressure liquid-phase refrigerant having passed through the condenser  200  into low-temperature and low-pressure liquid-phase refrigerant. 
     The evaporator  400  serves to change the low-temperature and low-pressure liquid-phase refrigerant having passed through the expansion valve  300  into low-temperature and low-pressure gas-phase refrigerant. 
     The rotary compressor  100  serves as a pump to circulate refrigerant in the air conditioning system. Specifically, the rotary compressor  100  serves to increase the pressure of refrigerant to a saturation pressure corresponding to a condensation temperature sufficient to suction low-temperature and low-pressure gas-phase refrigerant evaporated in the evaporator, thereby allowing the low-temperature and low-pressure gas-phase refrigerant to be liquefied in the condenser  200 . 
     As illustrated in  FIGS. 1 to 4 , the variable capacity rotary compressor  100  may vary the compression capacity thereof via forward or rearward movement of the first vane  38 . The forward or rearward movement of the first vane  38  is determined based on a difference between the pressure of refrigerant at the rear of the first vane  38  and the pressure of refrigerant introduced into the first compressing chamber  31   a  through the first suction pipe  12 . In this case, a space  53  at the rear of the first vane  38  communicates with the discharge pipe  11  and thus, has the same pressure as that of the compressed refrigerant discharged through the discharge pipe  11 . 
     If the pressure of refrigerant at the rear of the first vane  38  is greater than the pressure of refrigerant at the front of the first vane  38 , i.e. inside the first compressing chamber  31   a , the first vane  38  is moved forward into the first compressing chamber  31   a  such that the tip of the first vane  38  is supported by the first roller  36 . Thereby, the interior of the first compressing chamber  31   a  is divided into a refrigerant suction region and a refrigerant compression region by the first vane  38 . In this way, refrigerant is compressed within the first compressing chamber  31   a.    
     If the pressure of refrigerant inside the first compressing chamber  31   a  is similar to or greater than the pressure of refrigerant at the rear of the first vane  38 , the first vane  38  is moved rearward from the first compressing chamber  31   a  such that the tip end of the first vane  38  is spaced apart from the first roller  36 . Thus, the first vane  38  does not divide the interior of the first compressing chamber  31   a , causing the first roller  36  located in the first compressing chamber  31   a  to perform idle rotation. In this way, refrigerant is not compressed within the first compressing chamber  31   a.    
     The second vane  39 , installed in the second compressing chamber  32   a , is elastically supported at a rear end thereof by the elastic member  39   a . Thus, in a state in which the tip end of the second vane  39  comes into contact with the second roller  37 , the second vane  39  is moved forward or rearward in a radial direction of the second compressing chamber  32   a  depending on rotation of the second roller  37 , thereby dividing the second compressing chamber  32   a  into a refrigerant compression region and a refrigerant suction region. In this way, refrigerant is always compressed in the second compressing chamber  32   a.    
     As described above, the refrigerant introduced into the second compressing chamber  32   a  is always compressed and discharged, whereas the refrigerant introduced into the first compressing chamber  31   a  is selectively compressed depending on forward or rearward movement of the first vane  38 . Accordingly, the capacity of the variable capacity rotary compressor  100  varies according to whether the refrigerant introduced into the first compressing chamber  31   a  is compressed or not. 
     When the first vane  38  is moved forward or rearward based on a difference between the pressure of refrigerant at the rear of the first vane  38  and the pressure of refrigerant at the front of the first vane  38 , i.e. between the pressure of refrigerant discharged through the discharge pipe  11  and the pressure of refrigerant inside the first compressing chamber  31   a , the pressure difference between the front and the rear of the first vane  38  may be controlled by the expansion valve  300 . 
     More specifically, as illustrated in the enthalpy-pressure diagram of  FIG. 6 , the refrigerant compressed in the rotary compressor  100  is increased in pressure to the highest pressure point Pd in the cycle ( 101 ) and then is liquefied by dissipating heat to the outside while passing through the condenser  200  ( 201 ). The liquefied refrigerant is lowered in pressure while passing through the expansion valve  300  ( 301 ) to the lowest pressure Ps and is changed into gas-phase refrigerant while passing through the evaporator  400  ( 401 ), thereby being returned to the rotary compressor  100 . 
     The expansion valve  300  operates based on the principle that pressure decreases when the area of the path narrows. In the air conditioning system, the pressure of refrigerant is lowered by providing the expansion valve with a smaller cross section than that of a refrigerant flow path. 
     In addition, the expansion valve  300  is configured to be opened or closed such that the cross section of a refrigerant passage region thereof may be controlled based on an opening rate of the expansion valve  300 . 
     When the opening rate of the expansion valve  300  is sufficiently reduced, the pressure of refrigerant is greatly lowered, causing a great difference between the highest pressure Pd and the lowest pressure Ps. On the contrary, when the opening rate of the expansion valve  300  is sufficiently increased, the pressure of refrigerant is only slightly lowered as designated by the arrows illustrated in the enthalpy-pressure diagram of  FIG. 6 , causing a reduced difference between the highest pressure Pd and the lowest pressure Ps. 
     In this case, the highest pressure Pd is substantially equal to the pressure of refrigerant discharged from the rotary compressor  100 , and the lowest pressure Ps is substantially equal to the pressure of refrigerant introduced into the rotary compressor  100 . 
     As described above, since the pressure of refrigerant discharged from the rotary compressor  100  is equal to the pressure of refrigerant discharged through the discharge pipe  11  and the pressure of refrigerant discharged through the discharge pipe  11  is equal to the pressure acting on the rear of the first vane  38 , the pressure at the rear of the first vane  38  is equal to the highest pressure Pd. 
     In addition, since the pressure of refrigerant Ps introduced into the rotary compressor  100  is equal to the pressure of refrigerant introduced into the first compressing chamber  31   a , the pressure at the front of the first vane  38  is equal to the lowest pressure Ps. 
     Accordingly, a pressure difference between the front and the rear of the first vane  38  may be controlled by controlling the opening rate of the expansion valve  300 . 
     When the opening rate of the expansion valve  300  is reduced, a difference between the highest pressure Pd and the lowest pressure Ps, i.e. a difference between the pressure at the rear of the first vane  38  and the pressure at the front of the first vane  38  is increased. In this case, the first vane  38  is moved forward into the first compressing chamber  31   a  such that the tip end of the first vane  38  is supported by the first roller  36 . Thereby, as the interior of the first compressing chamber  31   a  is divided into a refrigerant suction region and a refrigerant compression region by the first vane  38 , refrigerant is compressed in the first compressing chamber  31   a.    
     When the opening rate of the expansion valve  300  is increased, there is only a slight difference between the highest pressure Pd and the lowest pressure Ps, i.e. between the pressure of refrigerant at the rear of the first vane  38  and the pressure of refrigerant at the front of the first vane  38 . 
     As illustrated in  FIGS. 1 and 2 , a pulling member  63  is placed between an inner circumferential surface of the housing  10  and a rear end of the first vane  38 , and serves to force the first vane  38  rearward. Therefore, if force applied to the first vane  38  by the pulling member  63  is greater than a difference between the pressure at the front of the first vane  38  and the pressure at the rear of the first vane  38 , the first vane  38  is moved rearward away from the first compressing chamber  31   a  such that the tip end of the first vane  38  is spaced apart from the first roller  36 . Thereby, as the first compressing chamber  31   a  does not divide the interior of the first compressing chamber  31   a , the first roller  36  performs idle rotation and refrigerant is not compressed in the first compressing chamber  31   a.    
     The pulling member  63  used to force the first vane  38  rearward may be a magnet, a spring or the like. 
     The above-described effect, as illustrated in  FIG. 5 , may be obtained by adding a bypass valve  500  in parallel to the expansion valve  300 . 
     Specifically, the bypass valve  500  is connected in parallel to the expansion valve  300  so as to bypass a part of the refrigerant to be introduced into the expansion valve  300 . This has the effect of reducing a difference between the pressure at the front of the first vane  38  and the pressure at the rear of the first vane  38 , and causing the first vane  38  to be spaced apart from the first roller  36 . In this way, the capacity of the rotary compressor  100  may vary. 
       FIG. 7  is a sectional view illustrating a dividable vane provided in the variable capacity rotary compressor according to an embodiment. 
     As illustrated in  FIG. 7 , the first vane  38  may be divided into an upper first vane  38   a  and a lower first vane  38   b , and the pulling member  63  may be located only at the rear of the upper first vane  38   a.    
     In this case, the upper first vane  38   a  may be separated from the lower first vane  38   b  so as to be moved forward or rearward independently of the lower first vane  38   b.    
     If the opening rate of the expansion valve  300  is increased to reduce a difference between the highest pressure Pd and the lowest pressure Ps, i.e. a difference between the pressure at the front of the first vane  38  and the pressure at the rear of the first vane  38 , only the upper first vane  38   a  is moved rearward by the pulling member  63  provided at the rear of the upper first vane  38   a.    
     Even if the upper first vane  38   a  is moved rearward, the interior of the first compressing chamber  31   a  is not divided, causing the first roller  36  located in the first compressing chamber  31   a  to perform idle rotation and preventing compression of refrigerant from taking place in the first compressing chamber  31   a.    
     As described above, as the first vane  38  is divided into the upper first vane  38   a  and the lower first vane  38   b  such that only the upper first vane  38   a  is moved forward or rearward, the compression capacity of the rotary compressor  100  may be more precisely controlled. 
     Meanwhile, the first compressing chamber  31   a  and the second compressing chamber  32   a  may have the same or different volumes. 
     Assuming that the first compressing chamber  31   a  and the second compressing chamber  32   a  have the same volume, the variable capacity rotary compressor according to the embodiment operates at up to the maximum capacity if refrigerant is compressed in the first compressing chamber  31   a , and operates at up to approximately 50% of the maximum capacity if the first compressing chamber  31   a  performs idle rotation. 
     Assuming that the first compressing chamber  31   a  and the second compressing chamber  32   a  do not have the same volume, for example, assuming that the volume of the first compressing chamber  31   a  is double that of the second compressing chamber  32   a , the variable capacity rotary compressor according to the embodiment operates at up to the maximum capacity if refrigerant is compressed in the first compressing chamber  31   a , and operates at up to approximately 33% of the maximum capacity if the first compressing chamber  31   a  performs idle rotation. 
     As is apparent from the above description, a variable capacity rotary compressor according to the embodiments may achieve improved compression efficiency, in particular, in a low-load region. 
     Further, material costs required to realize a variable compression capacity may be reduced, resulting in improved productivity of the variable capacity rotary compressor. 
     Although the embodiment has been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.