Abstract:
The present invention relates to a scroll compressor. The scroll compressor is configured to have bypass holes communicated with compression chambers so as to bypass a part of a compressed refrigerant and thus to modulate a capacity of the compressor, a middle pressure chamber and a valve. Accordingly, it is capable of simplifying a capacity modulation apparatus of the scroll compressor, thereby miniaturizing the compressor and reducing a fabrication cost. And, as the bypass holes are disposed to be adjacent to each other, an operating capacity of the compressor can be easily modulated with only one bypass valve, accordingly it is capable of reducing the number of bypass valve and of enhancing reliability.

Description:
RELATED APPLICATION 
       [0001]    The present disclosure relates to subject matter contained in priority Korean Application No. 10-2007-0109830, filed on Oct. 30, 2007, which is herein expressly incorporated by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a capacity modulation apparatus of a scroll compressor. 
         [0004]    2. Background of the Invention 
         [0005]    Generally, a scroll compressor is broadly used in an air conditioning system and has characteristics of high efficiency and low noise. The scroll compressor is implemented in a manner as follows. That is, two scrolls relatively orbit and then one pair of compression chambers are formed between the two scrolls. And, as the compression chambers continuously move toward a center, volume thereof is reduced. Accordingly, a refrigerant is consecutively sucked, compressed and discharged. 
         [0006]    In the related art scroll compressor, bypass holes are formed in the middle of the compression chambers and a part of a refrigerant implementing a middle pressure is moved toward a suction groove using the bypass holes so as to modulate a capacity of the compressor. Or, a discharge pipe and a suction pipe are connected to each other and a solenoid valve is installed therebetween so as to modulate the capacity of the compressor using a switching operation of the solenoid valve. 
         [0007]    However, in the related art, the manner using the bypass holes has the following problems. That is, since the bypass holes are formed to be symmetric to each other centering a discharge outlet, a plurality of valves are required to switch the bypass holes. Accordingly, a fabrication cost may increase. And, since it is required to control the bypass holes disposed to be remote from each other at the same time, reliability may decrease. And, the manner using the discharge pipe and the suction pipe connected to each other also has the following problems. That is, since the pipes are intricately arranged and valves should be installed at the pipes, the compressor may be enlarged. And, since the number of assembly processes may increase, the fabrication cost may increase. 
       SUMMARY OF THE INVENTION 
       [0008]    Therefore, an object of the present invention is to provide a scroll compressor which is capable of modulating a capacity of the compressor using bypass holes, of reducing the number of valves for controlling the modulation of the capacity, of enhancing reliability, of miniaturizing the compressor by simplifying pipes and of reducing a fabrication cost. 
         [0009]    To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a scroll compressor comprising a hermetic container, a fixed scroll fixed in the hermetic container and provided with a spiral shaped fixed wrap and an orbiting scroll provided with a spiral shaped orbiting wrap engaged with the fixed wrap of the fixed scroll so as to implement one pair of compression chambers. At least one of the fixed scroll and the orbiting scroll is provided with one or more bypass holes communicated with the compression chambers. A chamber having a specific volume is formed at an outlet side of the bypass holes. And, a valve is installed at one side of the chamber so as to open/close an inner space of the chamber. 
         [0010]    The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. 
           [0012]    In the drawings: 
           [0013]      FIG. 1  is a cross section view showing one exemplary low pressure type scroll compressor in accordance with the present invention; 
           [0014]      FIG. 2  is a cross section view showing a main part of the scroll compressor of  FIG. 1 ; 
           [0015]      FIG. 3  is a planar view showing a non-symmetric fixed scroll of the scroll compressor of  FIG. 1 ; 
           [0016]      FIGS. 4 and 5  are cross section views respectively showing operations of a bypass apparatus in a power operation mode and a saving operation mode of the scroll compressor of  FIG. 1 ; 
           [0017]      FIGS. 6 to 8  are cross section views showing other embodiments of a bypass apparatus in the scroll compressor of  FIG. 1 ; 
           [0018]      FIG. 9  is a planar view showing a symmetric fixed scroll of the scroll compressor in accordance with the present invention; and 
           [0019]      FIG. 10  is a cross section view showing one exemplary high pressure type scroll compressor in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    Hereafter, description will now be given in detail of one embodiment of a scroll compressor according to the present invention with accompanying drawings. 
         [0021]      FIGS. 1 to 3  are cross section views showing one exemplary embodiment of a scroll compressor in accordance with the present invention. 
         [0022]    As shown in  FIGS. 1 and 2 , the scroll compressor in accordance with the present invention includes a hermetic container  10  provided with a gas suction pipe (SP) and a gas discharge pipe (DP), a main frame  20  and a sub frame  30  respectively fixed at upper and lower portions of the hermetic container  10 , a driving motor  40  mounted between the main frame  20  and the sub frame  30  so as to generate a rotational force, a fixed scroll  50  fixed over the main frame  20 , an orbiting scroll  60  orbitably disposed on the main frame  20  so as to form one pair of compression chambers (P) by being engaged with the fixed scroll  50 , an Oldham&#39;s ring  70  interposed between the orbiting scroll  60  and the main frame  20  so as to orbit the orbiting scroll  60  with preventing a rotation of the orbiting scroll  60 , a discharge muffler  80  fixed over the fixed scroll  50  so as to remove noise of a discharged refrigerant and a bypass apparatus  90  installed at one side of the discharge muffler  80  so as to bypass a refrigerant implementing a middle pressure in the compression chambers (P). 
         [0023]    The hermetic container  10  includes a cylindrical case  11  for installing the driving motor  40  therein, and an upper cap  12  and a lower cap  13  respectively coupled to upper and lower sides of the cylindrical case  11 . The gas suction pipe (SP) is coupled to the cylindrical case  11  and also coupled to the upper cap  12  in a direction perpendicular to a length direction of the hermetic container  10 . The gas discharge pipe (DP) is coupled to be communicated with a discharge space  81  of the discharge muffler  80  by passing through the upper cap  12 . 
         [0024]    As shown in  FIG. 3 , the fixed scroll  50  is provided with a fixed wrap  51  in a spiral shape so as to form the compression chambers at a lower surface of a plate thereof. And, a suction groove  52  is formed at an outer edge side of the fixed wrap  51  and a discharge outlet  53  is formed in the center of the fixed wrap  51 . And, bypass holes  91  forming a part of the bypass apparatus  90  is formed at the plate of an intermediate portion of the fixed wrap  51 , that is, in the middle side fixed wrap. The fixed wrap  51  has a wrap length to be longer than that of the orbiting wrap  61  in a circumferential direction by approximately 180° so as to simultaneously form both of the compression chambers (P). Here, if the bypass holes  91  are formed at the orbiting scroll  60 , the orbiting wrap  61  of the orbiting scroll  60  may be longer than the fixed wrap  51  by approximately 180°. The bypass holes  91  may be formed to be received in a middle pressure chamber  92  on a straight line in a radial shape centering the discharge outlet  53  within a range of approximately 90° along a track of the orbiting scroll  60  so as to be respectively communicated with both of the compression chambers (P). Here, as the fixed scroll  50  and the orbiting scroll  60  are fabricated in a non-symmetric shape, that is, the fixed wrap  51  of the fixed scroll  50  is longer than the orbiting wrap  61  of the orbiting scroll  60 , even if the bypass holes  91  are disposed to be adjacent to each other, it is capable of normally compressing the refrigerant with maintaining balance between the pressure of the compression chambers (P). 
         [0025]    The orbiting wrap  61  is formed at an upper surface of the plate of the orbiting scroll  60  in the spiral shape so as to form one pair of compression chambers (P) by being engaged with the fixed wrap  51 . 
         [0026]    As shown in  FIG. 2 , the discharge muffler  80  has an opened lower surface, thus the discharge space  81  is formed so as to receive the discharge outlet  53  of the fixed scroll  60  therein. The middle pressure chamber  92  forming a part of the bypass apparatus  90  and serving to receive the bypass holes  91  of the fixed scroll  50  is formed at one side of the discharge space  81 . And, a bypass tube  93  forming a part of the bypass apparatus  90  is inserted into one side of the middle pressure chamber  92  so as to bypass the refrigerant having been bypassed to the middle pressure chamber  92  to an inner space of the hermetic container  10 , that is, a suction space  10   a . The bypass tube  93  is coupled to the discharge muffler  80  by being sealed in a welding manner so as to prevent the refrigerant from being leaked, preferably. 
         [0027]    As shown in  FIG. 2 , the bypass apparatus  90  includes the bypass holes  91 , the middle pressure chamber  92 , the bypass tube  93  and a bypass valve  94  fixed at the discharge muffler  80  or the fixed scroll  50  by an additional fixing member (not shown) so as to switch the bypass tube  93 . The bypass valve  94  is installed to be slidable with respect to the bypass tube  93  so that a switching unit (not shown) can switch the bypass tube  93  when a power is applied. And, a power terminal  95  for applying the power to the bypass valve  94  is installed at the upper cap  12  of the hermetic container  10 . 
         [0028]    The bypass holes  91  may be implemented as a plurality of circular holes as shown in  FIG. 3 , as a long slit shape though it is not shown, or other shapes. 
         [0029]    Regarding unexplained reference numerals,  41  denotes a stator,  42  denotes a rotor and  43  denotes a driving shaft. 
         [0030]    Operations of the scroll compressor in accordance with the present invention will be explained. 
         [0031]    When the power is applied to the driving motor  40 , the driving shaft  43  orbits with the rotor  42 . Then, the orbiting scroll  60  orbits on the main frame  20  by the Oldham&#39;s ring  70  by an eccentric distance, and at the same time, one pair of compression chambers (P) moving toward the center are consecutively formed between the fixed wrap  51  and the orbiting wrap  61 . The compression chambers (P) are moved toward the center by the continuous orbiting motion of the orbiting scroll  60 , thus the volume thereof is reduced and the refrigerant gas is sucked and compressed. And then, the refrigerant gas is discharged to a refrigeration cycle through the discharge space  81  of the discharge muffler  80  and the gas discharge pipe (DP). 
         [0032]    Here, a capacity of the compressor can be varied by operating the bypass valve  94 . For example, when the compressor is in a power operation mode, as shown in  FIG. 4 , the power is not applied to the bypass valve  94  and thus the bypass valve  94  keeps closing the bypass tube  93 . Accordingly, the middle pressure chamber  92  is still filled with the middle pressure refrigerant and the middle pressure refrigerant is not bypassed into the inner space  10   a  of the hermetic container  10  implementing a suction pressure, thus the refrigerant of the compression chamber  10  is continuously moved and compressed. 
         [0033]    On the other hand, when the compressor is in a saving mode, as shown in  FIG. 5 , the power is applied to the bypass valve  94  and thus the bypass tube  93  is opened by the bypass valve  94 . Accordingly, the refrigerant in the compression chambers (P) is bypassed into the inner space  10   a  of the hermetic container  10  implementing the suction pressure through the middle pressure chamber  92  and the bypass tube  93  and thus the compressor is not operated or operated in a mode requiring less capacity than that in the power mode. 
         [0034]    As the compressor comes to have the variable capacity resulting from bypassing a part of the compressed refrigerant to one bypass valve using the bypass holes, it is capable of simplifying an apparatus for modulating the capacity of the compressor, thereby being capable of providing a capacity modulation apparatus of the scroll compressor which requires low costs and is highly reliable. 
         [0035]    Other embodiments of the scroll compressor in accordance with the present invention will be explained. 
         [0036]    The gas discharge pipe (DP) is disposed in a direction perpendicular to the length direction of the hermetic container  10  of the gas discharge pipe (DP) in the first embodiment, however, as shown in  FIG. 6 , the gas discharge pipe (DP) is disposed in the same direction with respect to the length direction (axial direction) of the hermetic container  10  in this embodiment. Here, the positions of the bypass holes  91  and the configuration of the bypass valve  94  are same as those of the first embodiment. In this embodiment, as the gas discharge pipe (DP) is disposed in the direction same as the length direction of the hermetic container  10 , the gas discharge pipe (DP) can be easily connected to the discharge muffler  80 , thereby simplifying a fabrication process. 
         [0037]    And, the middle pressure chamber  92  is formed in the discharge muffler  80  in the abovementioned embodiments, however, as shown in  FIG. 7 , the middle pressure chamber  92  is separated from the discharge muffler  80  in this embodiment. Here, the positions of the bypass holes  91  and the configuration of the bypass valve  94  are same as those of the first embodiment. In this embodiment, as the middle pressure chamber  92  is not formed in the discharge muffler  80  and is configured by installing an additional chamber member  96  at the fixed scroll  50 , it is capable of preventing the refrigerant from being leaked between the discharge space  81  of the discharge muffler  80  and the middle pressure chamber  92 . 
         [0038]    And, the refrigerant bypassed in the middle of the compression chambers (P) is collected under a state that the middle pressure chamber  92  is provided and the middle pressure chamber  92  is connected to the bypass tube  93  so as to install the bypass valve  94  at the bypass tube  93  in the abovementioned embodiments, however, as shown in  FIG. 8 , a valve hole  97  is formed at the discharge muffler  80  with excluding the middle pressure chamber  92  and the bypass tube  93  and the bypass valve  94  is directly coupled to be slidable into the valve hole  97  in this embodiment. Here, the positions of the bypass holes  91  are same as those of the abovementioned embodiments. In this embodiment, as the bypass holes  91  are directly opened/closed by the bypass valve  94 , the discharge muffler  80  is further provided with a bypass channel  98  to be communicated with the suction pressure area of the hermetic container through the valve hole  97 . Here, though it is not shown, it may be configured to directly open/close the bypass holes using an additional fixing member (not shown) without directly coupling the bypass valve  94  to the discharge muffler  80 . 
         [0039]    Meanwhile, the fixed wrap of the fixed scroll and the orbiting wrap of the orbiting scroll are formed in a non-symmetric shape in the abovementioned embodiments, however, the fixed wrap and the orbiting wrap can be formed to have the same wrap length to each other, i.e., in a symmetric shape. For example, as shown in  FIG. 9 , the fixed scroll  50  is provided with the fixed wrap  51  in the spiral shape so as to form the compression chambers at the lower surface of the plate. And, the suction groove  52  is formed at the outer edge side of the fixed wrap  51  and the discharge outlet  53  is formed at the center of the fixed wrap  51 . And, the bypass holes  91  forming a part of the bypass apparatus  90  are formed at both sides of the plate at the intermediate portion of the fixed wrap  51 , that is, in the middle side fixed wrap with a phase difference of approximately 180°. The length of the fixed wrap  51  and the orbiting wrap  61  may be same to each other in the circumferential direction so as to simultaneously form both of the compression chambers (P). The bypass holes  91  are separately received in the inner spaces of the plurality of middle pressure chambers  92  fixed at the upper surface of the fixed scroll  50  with the phase difference of approximately 180°. The plurality of middle pressure chambers  92  may be respectively integrated with the muffler  80  or be assembled to the muffler  80  after being separately fabricated. And, the middle pressure chambers may be implemented in one arc shape so as to receive the plurality of bypass holes therein. 
         [0040]    The abovementioned embodiments are applied to a low pressure type scroll compressor in which the inner space of the hermetic container is configured to implement the suction pressure, however, as shown in  FIG. 10 , can be applied to a high pressure type scroll compressor in which the inner space  10   a  of the hermetic container  10  is configured to implement a discharge pressure. Here, in the high pressure type scroll compressor, since the inner space  10   a  of the hermetic container  10  is configured to implement the discharge pressure, an electromagnet of the bypass valve  94  may be badly influenced under a high pressure atmosphere, which causes the compressor to have a degraded performance. Thus, in this case, the bypass holes may be formed at the fixed scroll and a housing  96  having the middle pressure chamber  92  receiving the bypass holes is installed. And, the bypass tube  93  communicated with the middle pressure chamber  92  of the housing  96  may be extended to the outside of the hermetic container  10  and then connected to the gas suction pipe (SP) so as to install the bypass valve  94  at the outside of the hermetic container  10 . Here, the positions of the bypass holes  91  and the configuration of the middle pressure chamber  92  are same as those of the abovementioned embodiments. 
         [0041]    The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present disclosure. The present teachings can be readily applied to other types of apparatuses. This description is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art. The features, structures, methods, and other characteristics of the exemplary embodiments described herein may be combined in various ways to obtain additional and/or alternative exemplary embodiments. 
         [0042]    As the present features may be embodied in several forms without departing from the characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalents of such metes and bounds are therefore intended to be embraced by the appended claims.