Patent Publication Number: US-7585164-B2

Title: Backflow preventing apparatus for compressor

Description:
RELATED APPLICATION 
   The present application claims priority to Korean Application No. 10-2006-0031625, filed on Apr. 6, 2006, Korean Application No. 10-2006-0081978, filed in Korea on Aug. 28, 2006, and Korean Application No. 10-2007-0016229, filed in Korea on Feb. 15, 2007, all of which are herein expressly incorporated by reference in their entirety. 
   BACKGROUND 
   1. Field 
   A compressor, and more particularly, a backflow preventing apparatus for a compressor are disclosed herein. 
   2. Background 
   Generally, a compressor serves to compress a refrigerant at a low pressure into a refrigerant at a high pressure. The compressor may include a driving motor that generates a driving force at an inner space of a hermetic casing, and a compression part that compresses a refrigerant using the driving force received from the driving motor. The compressor may be classified into, for example, a reciprocating compressor, a rotary compressor, a scroll compressor, or a centrifugal compressor, according to the method of compressing the refrigerant. However, the compressor may have degraded function or may be damaged when a discharged refrigerant backflows into the inner space of the casing. Accordingly, a backflow preventing apparatus, including a backflow preventing valve is provided to prevent discharged refrigerant from backflowing into the casing. However, the conventional backflow preventing apparatus have various problems. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein: 
       FIG. 1  is a longitudinal sectional view of a scroll compressor in accordance with an embodiment; 
       FIG. 2  is a longitudinal sectional view of a backflow preventing apparatus of  FIG. 1  according to an embodiment; 
       FIG. 3  is a longitudinal sectional view of a backflow preventing apparatus of  FIG. 1  according to another embodiment; 
       FIG. 4  is a longitudinal sectional view of a low pressure type scroll compressor having a backflow preventing apparatus according to another embodiment; 
       FIG. 5  is an exploded perspective view of a valve seat of the backflow preventing apparatus of  FIG. 4  according to an embodiment; 
       FIG. 6  is an exploded perspective view of a valve seat of the backflow preventing apparatus of  FIG. 4  according to another embodiment; 
       FIG. 7  is a longitudinal sectional view showing an assembled state of the backflow preventing apparatus of  FIG. 4 ; 
       FIG. 8A  is a longitudinal sectional view showing the backflow preventing apparatus of  FIG. 4  when the compressor is normally operated; 
       FIG. 8B  is a longitudinal sectional view showing the backflow preventing apparatus of  FIG. 4  when the compressor is stopped; 
       FIG. 9  is a longitudinal sectional view showing an assembled state of the backflow preventing apparatus according to another embodiment; 
       FIG. 10  is a longitudinal sectional view showing a state in which an elastic member is provided at a check valve of the backflow preventing apparatus of  FIG. 4 ; 
       FIG. 11  is a longitudinal sectional view showing a check valve of a backflow preventing apparatus according to another embodiment; 
       FIGS. 12 to 14  are longitudinal sectional views showing each installation position of a backflow preventing apparatus according to another embodiment; and 
       FIG. 15  is a longitudinal sectional view showing a high-pressure type scroll compressor having a backflow preventing apparatus according to an embodiment. 
   

   DETAILED DESCRIPTION 
   Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. The backflow preventing apparatus according to embodiments is shown implemented in both a low pressure type scroll compressor and a high pressure type scroll compressor; however, the backflow preventing apparatus according to embodiments may implemented in other types of compressors as well. 
   A scroll compressor having a backflow preventing apparatus according to an embodiment will be explained hereinafter. Scroll compressors are widely applied to, for example, air conditioning systems due to their high efficiency and low noise output. A scroll compressor may include a driving motor and a compression part at an inner space of a casing, the compression part including compression chambers formed by two scrolls engaged with each other. In the scroll compressor, a refrigerant is respectively sucked into a pair of compression chambers that are formed by a wrap of an orbiting scroll engaged with a wrap of a fixed scroll. While the refrigerant sucked into the respective compression chambers moves along an orbit of the orbiting scroll, it is compressed and then discharged to the inner space of the casing at a final compression chamber. 
     FIG. 1  discloses a scroll compressor according to one embodiment, which includes a casing  10  to which a suction pipe  11  and a discharge pipe  12  are connected, a main frame  20  and a sub frame (not shown) fixed to upper and lower sides of an inner circumferential surface of the casing  10 , a driving motor  30  with stator  31  disposed between the main frame  20  and the sub frame that generates a rotation force, a fixed scroll  40  fixed to an upper surface of the main frame  20  and having an involute wrap  42  at a lower surface of a plate  41 , an orbiting scroll  50  having an involute wrap  52  at an upper surface of a plate  51  that performs an orbiting motion by being engaged with the involute wrap  42  of the fixed scroll  40  so that a plurality of compression chambers are formed, an Oldham&#39;s ring  60  disposed between the orbiting scroll  50  and the main frame  20  that orbits the orbiting scroll  50  while preventing the orbiting scroll  50  from rotating, a high-low pressure separating plate  70  coupled to a rear surface of the fixed scroll  40  that divides an inner space of the casing  10  into a suction space  13  and a discharge space  14 , and a backflow preventing apparatus  80  disposed at an outlet of the discharge space  14  that prevents compression gas discharged to the discharge pipe  12  from backflowing. 
   In the scroll compressor of  FIG. 1 , when power is supplied to the driving motor  30 , a driving shaft  33  of the driving motor  30  is rotated together with a rotor  32 . Accordingly, the orbiting scroll  50  performs an eccentric orbiting motion on an upper surface of the main frame  20  via the Oldham&#39;s ring  60 , thereby forming a pair of compression chambers P that consecutively move between the orbiting wrap  52  and the fixed wrap  42 . At the same time, as the orbiting scroll  50  continuously performs an orbiting motion, a refrigerant is sucked into an outermost compression chamber through an inlet  43  of the fixed scroll  40 . While the refrigerant moves to a center of a scroll along an orbit of the orbiting scroll  50 , it is compressed and is discharged into the discharge space  14  of the casing  10  through a discharge port  44  of the fixed scroll  40  at the final compression chamber. Then, the refrigerant is discharged, for example, to a condenser of a refrigerating cycle provided in an air conditioning system through the discharge pipe  12  thus to circulate the refrigerant through the refrigerating cycle. 
   When the compressor is stopped, a pressure of the discharge space  14  is lower than that of the discharge pipe  12 . As a result, the refrigerant discharged to the discharge pipe  12  may backflow into the discharge space  14 . However, since a backflow preventing apparatus  80  is disposed at the outlet of the discharge space  14 , the refrigerant having been discharged to the discharge pipe  12  is prevented from backflowing into the discharge space  14  due to the pressure difference. 
   Examples of backflow preventing apparatus provided in the outlet of the discharge space have been disclosed, for example, in the U.S. Pat. No. 5,141,420, No. 6,171,084, and No. 6,428,292. The backflow preventing apparatus of  FIG. 1  is configured so that a check valve serves to open and close a space between the discharge space and the discharge pipe due to a pressure difference. The backflow preventing apparatus of  FIG. 1  will be explained in more detail with reference to  FIGS. 2 and 3 . 
   Referring to  FIG. 2 , the backflow preventing apparatus  80  includes a housing  81  having a first refrigerant passing hole  85  through which the discharge space  14  and the discharge pipe  12  of the casing  10  communicate with one another, and fixedly-coupled to an inner circumferential surface of the casing  10 ; a valve seat  82  fixedly-coupled to an entrance of the housing  81  and having a second refrigerant passing hole  86  at an edge thereof; a stop  83  fixedly-coupled to an exit of the housing  81  and having a third refrigerant passing hole  87  at a center thereof; and a check valve  84  formed, for example, of a thin plate so as to freely move between the valve seat  82  and the stop  83  and having a fourth refrigerant passing hole  88  at a center thereof, that opens and closes the second refrigerant passing hole  86  of the valve seat  82 . 
   The backflow preventing apparatus  80  allows a refrigerant to be smoothly discharged and prevents a refrigerant from backflowing by opening and closing the second refrigerant passing hole  86  of the valve seat  82  according to an operation state of the compressor. When the compressor is normally operated, since a pressure of the discharge space  14  is higher than that of the discharge pipe  12 , the check valve  84  is pushed to the stop  83  due to the pressure difference. Since the second refrigerant passing hole  86  of the valve seat  82  is opened, the refrigerant discharged to the discharge space  14  is discharged to the discharge pipe  12 . However, when the compressor is stopped, since the pressure of the discharge space  14  is lower than that of the discharge pipe  12 , the check valve  84  is pushed to the valve seat  82  due to the pressure difference. As the second refrigerant passing hole  86  of the valve seat  82  is closed, the refrigerant discharged to the discharge pipe  12  is prevented from backflowing into the discharge pipe  14 . 
   Referring to  FIG. 3 , in the backflow preventing apparatus  80 , an entrance of the discharge pipe  12  is stepped without having the housing, the stop, and the valve seat, thereby forming the housing  81  for receiving the check valve  84  and the stop  83 . Also, the valve seat  82  is formed at an outer surface of the casing  10  received in the entrance of the discharge pipe  12 . Herein, the check valve  84  opens and closes a space between the discharge space  14  and the discharge pipe  12  freely moving due to a pressure difference. 
   However, the backflow preventing apparatus shown in  FIG. 1-3  has the following problems. Since the check valve  84  moves only due to the pressure difference, it has a low responsive characteristic and a delayed closing speed. As a result, the refrigerant discharged to the discharge pipe  12  backflows, and a performance of the compressor is lowered. Further, the check valve  84  collides with the valve seat  82  when closed, and collides with the stop  83  when opened, thereby causing collision noise at the check valve and vibration noise for the compressor. 
   Hereinafter, a backflow preventing apparatus according to another embodiment will be explained in more detail herein below. 
     FIGS. 4 to 8B  are views of a backflow preventing apparatus according another embodiment implemented in a scroll compressor. The scroll compressor of  FIG. 4  may include a casing  100  to which a suction pipe  110  and a discharge pipe  120  are connected; a main frame  200  fixed to the inside of the casing  100 ; a driving motor  300  fixed to the inside of the casing  100  that generates a driving force; a fixed scroll  400  fixed to an upper surface of the main frame  200 ; an orbiting scroll  500  disposed on an upper surface of the main frame  200  and eccentrically coupled to a driving shaft  330  of the driving motor  300 , forming a pair of compression chambers P and performing an orbiting motion by being engaged with the fixed scroll  400 ; an Oldham&#39;s ring  600  disposed between the orbiting scroll  500  and the main frame  200 , that causes the orbiting scroll  500  to orbit while preventing the orbiting scroll  500  from rotating; a high-low pressure separating plate  700  that divides an inner space of the casing  100  into a suction space  130  and a discharge space  140 ; and a backflow preventing apparatus  800  inserted into the discharge space  140  of the casing  100 , having an entrance connected to the casing  100 , and having an exit connected to the discharge pipe  120 , that prevents a refrigerant discharged to the discharge pipe  120  from backflowing into the discharge space  140  of the casing  100 . 
   The suction pipe  110  may be connected to the suction space  130  of the casing  100 , and the discharge pipe  120  may be connected to the discharge space  140  of the casing  100 . The discharge pipe  120  may be insertion-coupled to a valve housing  810  of the backflow preventing apparatus  800 , thereby connected to the discharge space  140 . 
   An involute wrap  420  of the fixed scroll  400  and an orbiting wrap  520  of the orbiting scroll  500  may be disposed on plates  410  and  510 , respectively. The involute wrap  420  of the fixed scroll  400  and an orbiting wrap  520  of the orbiting scroll  500  may be engaged with each other, thereby forming a pair of compression chambers P that consecutively move. An inlet  430  through which an outermost compression chamber communicates with the suction space  130  of the casing  100  may be disposed at one lower edge of the fixed scroll  400 . An outlet  440  with which the discharge space  140  of the casing  100  communicates at a final compression chamber may be disposed at a middle portion of the fixed scroll  400 . A check valve (not shown) that prevents the refrigerant discharged to the discharge space  140  of the casing  100  from backflowing into the compression chamber P may be disposed at an exit of the outlet  440 . 
   The high-low pressure separating plate  700  may be formed as a ring-shaped plate having a predetermined width so that an inner circumferential surface thereof may be coupled to an upper surface of the fixed scroll  400  and an outer circumferential surface thereof may be coupled to the casing  100 . Reference numeral  310  denotes a stator,  320  denotes a rotor, and  450  denotes a sub frame. 
   As shown in  FIGS. 5 to 7 , the backflow preventing apparatus  800  may include a valve housing  810  adhered to an inner wall surface of the casing  100 , a valve seat  820  fixed to the inside of the valve housing  810  and having a refrigerant passing hole  821  at a center thereof, and a check valve  830  rotatably disposed on the valve seat  820  so as to open and close the refrigerant passing hole  821  of the valve seat  820  by being rotated that prevents a discharged refrigerant from backflowing. 
   The valve housing  810  may be disposed in the discharge space  140  of the casing  100 , and both ends thereof may be opened so that the discharge space  140  and the discharge pipe  120  can may communicate with each other. One of the ends of the valve housing  810  may have a tapered cylindrical shape to which the discharge pipe  120  may be connected. The tapered portion may be partially inserted into a through hole  101  of the casing  100 , and may be coupled thereto by, for example, welding. The valve housing  810  may be integrally coupled to the end of the tapered portion so that the valve housing  810  and discharge pipe  120  constitute one module. Accordingly, when the valve housing  810  is coupled to the casing  100 , the discharge pipe  120  may be coupled thereto together therewith. 
   The valve housing  810  may have a seat supporting portion  811  that supports the valve seat  820 . The seat supporting portion  811  may be formed by being protruded from an inner circumferential surface of the valve housing  810 , or by contracting both ends of an entrance of the valve housing  810 . 
   The valve seat  820  may have a ring shape having the first refrigerant passing hole  821  at a center thereof. The valve seat  820  may be forcibly inserted into the valve housing  810 , or may be fixed to the valve housing  810 , such as by welding or a by a bolt. The valve seat  820  may be integrally formed in the valve housing  810 . 
   The valve seat  820  may have hinge protrusions  822  for inserting a hinge portion  831  of the check valve  830  and rotating the hinge portion  831 , at right and left upper portions. A side hinge hole  823  for inserting a hinge pin  840  may be formed at a center of the hinge protrusion  822  in correspondence to a side hinge hole  833  of the check valve  830 . The side hinge hole  823  may be formed on the same vertical line as a front end of the valve seat  820 , or may be disposed at a discharge side so that the check valve  830  may be smoothly closed by a pressure difference and its weight. 
   As shown in  FIG. 5 , a sealing protrusion  824  may be formed near the refrigerant passing hole  821  so that a front end of the valve seat  820  may be in linear contact with a compression surface of the check valve  830 . However, as shown in  FIG. 6 , a buffering member  825  may be disposed so that a refrigerant may be prevented from leaking between the check valve  830  and the valve seat  820  when the check valve  830  is closed, and so that an impact due to collision of the check valve  830  with another component may be buffered. The buffering member  825  may be formed to have a circular section so as to be in linear-contact with the check valve  830 . The buffering member  825  may be disposed at the compression surface of the check valve  830 . 
   As shown in  FIGS. 5 to 7 , the check valve  830  may have a hinge portion  831  configured to be hinge-coupled to the valve seat  820  at one end thereof, and an opening/closing portion  832  for opening and closing the refrigerant passing hole  821  of the valve seat  820  at another end thereof. The opening/closing portion  832  may have a disc shape. Further, the check valve  830  may be formed to be thicker towards the opening/closing portion  832  from the hinge portion  831  so as to be quickly opened. 
   The side hinge hole  833  may be formed at a center of the hinge portion  831  in correspondence to the side hinge hole  823  of the valve seat  820 . The side hinge hole  833  may be formed on the same vertical line as the compression surface of the check valve  830 , or may be disposed at a discharge side so that the check valve  830  may be smoothly closed by a pressure difference and its weight. The check valve  830  may have a valve stopping surface  834  inclined at a certain angle for limiting an opened angle of the check valve  830  being opened when an outer circumferential surface of the hinge portion  831  comes into contact with the valve seat  820 . As shown in  FIG. 9 , a valve stopping protrusion  835  for limiting an opened angle of the check valve  830  by coming into contact with an inner circumferential surface of the valve housing  810  may be disposed at a compression rear surface of the opening/closing portion  832 . 
   The check valve  830  may be formed of a thin metallic plate with consideration to rigidity and elasticity, or may be formed of an engineered plastic material, such as peek, with consideration to noise and cost. 
   As shown in  FIG. 10 , an elastic member  850 , such as a torsion spring, for accumulating an elastic force when the check valve  830  is opened and being restored when the check valve  830  is closed may be installed between the check valve  830  and the valve seat  820 . Reference numeral  836  denotes a spring supporting protrusion. Refrigerant backflow may be effectively prevented by enhancing a closing speed of the check valve  830 . 
   Operation and effect of the backflow preventing apparatus according to an embodiment will be explained herein below. 
   When power is supplied to the driving motor  300 , the driving shaft  330  rotates, causing the orbiting scroll  500  coupled to the driving shaft  330  to eccentrically orbit by being engaged with the fixed scroll  400 . When the orbiting scroll  500  progressively moves within the fixed scroll  400 , a pair of compression chambers P having decreased volume toward the center of the scrolls is formed. A refrigerant is sucked into the suction space  130  of the casing  100  through the suction pipe  110 , and is sucked to an outermost compression chamber through the outlet  430  of the fixed scroll  400 . Then, the refrigerant is compressed while moving towards a final compression chamber, and is discharged into the discharge space  140  of the casing  100 . The refrigerant opens the check valve  830  provided at an entrance of the valve housing  810  by pushing, moves into the discharge pipe  140  through the refrigerant passing hole  821  of the valve seat  820 , and is discharged from the compressor. 
   The process for opening and closing the check valve will be explained in detail herein below. 
   As shown in  FIG. 8A , when the compressor is normally operated, a discharge pressure of a refrigerant applied to a front surface of the check valve  830  is greater than the sum of the pressure applied to a rear surface of the check valve  830  and the pressure due to the weight of the check valve  830 . Accordingly, the check valve  830  is opened by upwardly rotating around the hinge pin  840 . The refrigerant compressed through the refrigerant passing hole  821  is quickly discharged to the discharge pipe  120 . Since the valve stopping surface  834  having a predetermined inclination angle (α) is formed on an outer circumferential surface of the hinge portion  831  of the check valve  830 , it comes into contact with the valve seat  820 , thereby limiting an opened angle of the check valve  830 . 
   In contrast, as shown in  FIG. 8B , when the compressor is abnormally operated or stopped, a discharge pressure of a refrigerant applied to the front surface of the check valve  830  is less than the sum between the pressure applied to the rear surface of the check valve  830  and the pressure due to the weight of the check valve  830 . Accordingly, the check valve  830  is closed by downwardly rotating around the hinge pin  840 . In this position, the front surface of the check valve  830  is in linear-contact with the sealing protrusion  824  of the valve seat  820 , thereby preventing the refrigerant discharged into the discharge pipe  120  from backflowing into the discharge space  140 . As shown in  FIG. 6 , when the buffering member  825  is disposed in the valve seat  820 , the discharge valve  830  is elastically buffered by the buffering member  825 . The buffering member  825  prevents or reduces collision noise or damage to the check valve, and refrigerant backflow is effectively prevented as the buffering member  825  is in linear-contact with the discharge valve  830 . 
   As the check valve is hinge-coupled to the valve seat, the check valve has a quick response speed when opened and closed. When the check valve is closed, it is quickly closed by the pressure difference between both sides thereof and its own weight. Accordingly, discharged refrigerant may be effectively prevented from backflowing, and thus efficiency of the scroll compressor may be enhanced. 
   Further, collision noise of the check valve may be reduced when the check valve is opened and closed, thereby reducing discharge noise of the compressor. When the check valve is opened, it is prevented from colliding with other components by the valve stopping surface. Also, when the check valve is closed, noise that occurs when the discharge valve collides with the valve seat is reduced by the buffering member provided at the valve seat. Accordingly, discharge noise of the compressor may be reduced. 
   The backflow preventing apparatus according to another embodiment will be explained herein below. 
   In the previously disclosed embodiment, the check valve  830  is implemented as a hinge type valve. However, in this embodiment, the check valve  861  may be implemented as a read type valve. 
   The check valve  861  may be formed of a thin metallic plate having its own elasticity, as shown in  FIG. 11 . One end of the check valve  861  may have a fixed end fixedly-coupled to the valve seat  820 , and another free end for opening and closing the refrigerant passing hole  821  of the valve seat  820  by freely rotating centered around the fixed end to a bent state. The check valve  861  may have an opened degree limited by its own elastic force, by an inner circumferential surface of the valve housing  810 , or by additionally disposing a retainer  862  at the rear surface of the check valve  830 . 
   Construction and operation of the valve housing  810  and the valve seat  820  of the backflow preventing apparatus are the same as those of the aforementioned embodiment, and thus their detailed explanation will be omitted. When the check valve  861  is opened, noise may be generated as the check valve  861  collides with the retainer  862 . However, if the retainer  862  is formed to have a curved surface in correspondence to an opened shape of the check valve, the collision noise may be reduced. 
   An installation position of the backflow preventing apparatus according to embodiments may be varied as follows. 
   As shown in  FIG. 12 , the valve housing  810  may be penetratingly-coupled to the casing  100 , for example, by one or more weldings  100   a ,  100   b . The valve housing  810  may be disposed on an outer surface of the casing  100 , as shown in  FIG. 13 , or may be insertion-coupled to a discharge plenum  900  coupled to the fixed scroll  410 , as shown in  FIG. 14 . 
   Referring to  FIG. 12 , when the valve housing  810  penetrates the casing  100 , an outer circumferential surface of the valve housing  810  penetrates the through hole  101  of the casing  100 , and is coupled to the casing by, for example, welding. With this configuration, the backflow preventing apparatus may be assembled even after the casing  100  is assembled. 
   Referring to  FIG. 13 , when the valve housing  810  is disposed on an outer surface of the casing  100 , a valve seat portion  150  having a refrigerant passing hole  151  may be integrally formed in the casing  100 . Also, the hinge protrusion  152  for rotatably coupling the hinge portion  831  of the check valve  830  may be disposed above the refrigerant passing hole  151 . An entrance of the valve housing  810  receives the check valve  830  thus to be hermetically-coupled to an outer surface of the casing  100 , and the discharge pipe  120  may be connected to an exit of the valve housing  810 . Since an additional valve seat for fixing the check valve  830  is not required, the number of components and the number of assembly processes may be reduced. Accordingly, a manufacturing cost may be reduced and productivity enhanced. 
   Referring to  FIG. 14 , when the valve housing  810  is coupled to a discharge plenum  900  that forms the discharge space, the valve housing  810  may be insertion-coupled to a through hole  910  of the discharge plenum  900 . Also, the discharge pipe  120  connected to the exit of the valve housing  810  may be penetratingly-coupled to the casing  100  sealed to an outer surface of the discharge plenum  900 . With this configuration, since the inner space of the casing  100  except the discharge plenum  900  forms a suction space of low pressure, a welding portion between the casing  100  and the discharge pipe  120  may receive less pressure, thus enhancing a sealing force. Also, since the discharge plenum  900  serves as a muffler, noise from the compressor may be reduced. The valve housing  810  may be adhered to an inner wall surface of the discharge plenum  900 . 
   In the aforementioned embodiment, the backflow preventing apparatus was applied to a low pressure type scroll compressor in which the inner space of the casing is divided into a suction space and a discharge space by the high-low pressure separating plate or the discharge plenum. However, as shown in  FIG. 15 , the backflow preventing apparatus may be applied to a high pressure type scroll compressor in which the suction pipe  110  is directly coupled to the fixed scroll  400  by penetrating the casing  100 , the inner space of the casing  100  maintains the discharge space  140  of a high pressure, and the discharge pipe  120  is connected to the discharge space  140 . That is, the backflow preventing apparatus, such as the hinge type valve or the read type valve according to embodiments disclosed herein, is disposed between the discharge space  140  and the discharge pipe  120 . Operation of the high-pressure type scroll compressor is the same as that of the low-pressure type scroll compressor, and thus its detailed explanation will be omitted. 
   Embodiments disclosed herein provide a backflow preventing apparatus for a compressor, such as a scroll compressor, capable of enhancing a performance of the compressor by quickly closing a check valve, enhancing a responsive characteristic of the check valve, and preventing a refrigerant from backflowing. 
   Embodiments disclosed herein also provide a backflow preventing apparatus for a compressor, such as a scroll compressor, capable of lowering vibration noise of the compressor by reducing collision noise that occurs when the check valve is opened and closed. 
   The backflow preventing apparatus for a compressor, such as a scroll compressor, includes a valve housing disposed between an inner space of a hermetic casing and a discharge pipe communicated with the inner space, a valve seat disposed at the valve housing and having a refrigerant passing hole so that the inner space of the casing and the discharge pipe can communicate with each other, and a check valve rotatably coupled to the valve seat, that opens and closes the refrigerant passing hole of the valve seat. 
   Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments. 
   Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.