Abstract:
The present invention has as an object providing a scroll compressor that transmits rotation of the eccentric axle side end plate of the orbiting scroll to the involute wrap side end plate with good efficiency, and sufficiently presses the involute wrap side end plate continuously against the fixed scroll without causing friction with the seal member; in order to attain this object, the present invention provides a scroll compressor providing a fixed scroll comprising an end plate and an involute wrap provided on one face of the end plate, and an orbiting scroll comprising and end plate, an engagement part provided on one face of the end plate and accommodating an eccentric axle therein, and an involute wrap provided on the other face of the end plate and forming a plurality of compression chambers by the combination with the involute wrap of the fixed scroll, wherein the end plate of the orbiting scroll is divided along the axial direction thereof into an involute wrap side end plate providing an involute wrap and an eccentric axle side end plate providing the engagement part, and furthermore, wherein a transmission mechanism is provided that permits movement of this involute wrap side end plate in the axial direction with respect to the eccentric axle side end plate but prevents movement in the radial or peripheral directions, and transmits the orbital movement of the eccentric axle side end plate to the involute wrap side end plate.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a scroll compressor, and in particular to a scroll compressor suitable for a vapor compression refrigerating cycle that uses a refrigerant having the supercritical region of carbon dioxide (CO 2 ), for example. 
     2. Description of the Related Art 
     Recently, a refrigeration cycle using carbon dioxide (referred to hereinbelow as a “carbon dioxide cycle”) as a working gas (refrigerant gas) has been proposed, for example, in Japanese Examined Patent Application, Second Publication, No. Hei 7-18602, as one measure for eliminating the use of Freon (dichlorofluoromethane) as a refrigerant in the vapor compression-type refrigerating cycle. This carbon dioxide cycle is identical to the conventional vapor compression-type refrigerating cycle that uses Freon. That is, as shown by A-B-C-D-A in FIG. 5, which shows a carbon dioxide Mollier chart, the carbon dioxide in the gaseous phase is compressed by a compressor (A-B), and this gas-phase carbon dioxide that has been compressed to a high temperature is cooled in a radiator, such as a gas cooler (B-C). Next, the carbon dioxide is decompressed using a decompressor (C-D), the carbon dioxide that has changed to a liquid phase is vaporized (D-A), and an external fluid such as air is cooled by removing its latent heat of vaporization. 
     However, the critical temperature of carbon dioxide is about 31°, which is low compared to the critical temperature of Freon, the conventional refrigerant. When the external temperature is high, during summer, for example, the temperature of carbon dioxide on the radiator side is higher than its critical temperature. This means that the carbon dioxide does not condense at the radiator outlet side. In FIG. 5, this is shown by the fact that the line BC does not cross the saturated liquid line SL. In addition, the state on the radiator output side (point C) is determined by the discharge pressure of the compressor and the temperature of the carbon dioxide at the radiator outlet side. Moreover, the temperature of the carbon dioxide at the radiator outlet side is determined by the radiating capacity of the radiator and the temperature of the uncontrollable external air. Due to this, the temperature at the radiator outlet cannot be substantially controlled. Therefore, the state of the radiator outlet side (point C) can be controlled by the discharge pressure of the compressor, that is, the pressure on the radiator outlet side. This means that in order to guarantee sufficient refrigerating capacity (difference in enthalpy) when the temperature of the external air is high, during summer, for example, as shown by E-F-G-H-E, the pressure on the radiator output side must be high. In order to attain this, the operating pressure of the compressor must be high in comparison to the refrigeration cycle used with conventional Freon. In the case of an air conditioning device for an automobile, for example, the operating pressure of the compressor when using Freon (Trademark R134) is about 3 kg/cm 2 , while in contrast, this pressure must be raised to about 40 kg/cm 2  for carbon dioxide. In addition, the operation stopping pressure when using Freon (Trademark R134) is about 15 kg/cm 2 , while in contrast it must be raised to about 100 kg/cm 2  for carbon dioxide. 
     Below, referring to FIG. 6, a typical scroll compressor as disclosed in Japanese Unexamined Patent Application, First Publication, No. Hei 5-149270, will be explained. As shown in FIG. 6, in a casing (not illustrated), a fixed scroll member  100 , an orbiting scroll member  101 , and an eccentric axle  102  are provided. 
     The fixed scroll  100  is formed by an end plate  100   a  providing a discharge port for discharging the compressor working gas (not illustrated) and an involute wrap  106   b  provided on one face of this end plate  100   a.    
     The orbiting scroll  101  is formed by an end plate  101   a  comprising an involute wrap side end plate  105  and an eccentric axle side end plate  106 , an involute wrap  101   b  provided on the face of the involute wrap side end plate  105  facing the end plate  100   a  of the fixed scroll, and an engagement part  103  provided on the face of the eccentric axle side end plate  106  not facing the involute wrap side end plate  105 , and accommodating therein the eccentric axle  102 , described below. The involute compression chamber  104  is formed by installing the fixed scroll  100  and the orbiting scroll  101  in the casing such that the involute wrap  100   b  of the fixed scroll  100  and the involute wrap  101   b  of the orbiting scroll  101  intermesh. Thereby, when the orbiting scroll  101  is rotated eccentrically with respect to the fixed scroll  100  by rotating the eccentric axle  102  installed in the engagement part  103 , while the working gas in the casing is compressed in compression chamber  104 , the working gas can be discharged from the discharge port provided on the end plate  100   a  of the fixed scroll  100 . 
     Moreover, as explained above, a scroll compressor using carbon dioxide as a working gas requires a high revolution and pressure. Thus, there is a concern of a deterioration in capacity due to leakage of the working gas. In order to prevent this, the orbiting scroll  101  presses against the fixed scroll  100 . That is, along the axial direction of the orbiting scroll  101 , the end plate  100   a  thereof is divided into an involute wrap side end plate  105  providing an involute projection  10   b  and an eccentric axle side end plate  106  providing an engagement part  103 . In addition, an sealed space  107  is formed between the involute wrap side end plate  105  and the eccentric axle side end plate  106 . Furthermore, on the involute wrap side end plate  105 , a narrow hole  108  is formed for introducing the high pressure working gas in the compression chamber  104  into the sealed space  107 . Moreover, in FIG. 6, reference numeral  109  denotes a seal part for sealing the sealed space  107 . 
     By adopting this kind of structure, one part of the high pressure working gas in the compression chamber  104  is introduced into the sealed space  107  via the narrow hole  108 , and fills the sealed space  107 . When comparing the upward force operating from the sealed space  107  on the involute wrap side end plate  105  and the downward force operating from the compression chamber  104  on the involute wrap side end plate  105 , the upward force is greater than the downward force, and thus the involute wrap side end plate  105  rises up as a whole and presses against the fixed scroll  100  side. Therefore, the end plate  100   a  of the fixed scroll  100  and the end plate  105  of the orbiting scroll  101  are on intimate contact. Thus, gas leakage from between the fixed scroll  100  and the orbiting scroll  101  is inhibited. 
     However, in the above-described conventional scroll compressor, the revolution of the eccentric axle side end plate  106  of the orbiting scroll  101  must be transmitted to the involute wrap side end plate  105  via the above-described seal member  109 . Thus, there is the problem of low transmission efficiency. 
     Thus, the friction on the seal member  109  becomes severe, and there is the problem that the operation of replacing the seal member  109  requires labor. 
     Furthermore, as described above, in the conventional scroll compressor, a compressed working gas is used, and the involute wrap side end plate  105  is pressed against the fixed scroll  100  side. However, in particular during operation of the scroll compressor, the compression or the working gas does not become sufficiently high, and thus the force pushing the involute wrap side end plate  105  against the fixed scroll  100  is weak and the compression efficiency is low. 
     In consideration of the above-described problems, it is an object of the present invention to provide a scroll compressor that transmits rotation of the eccentric axle side end plate  106  of the orbiting scroll to the involute wrap side end plate  105  with good efficiency, and sufficiently presses the involute wrap side end plate  105  continuously against the fixed scroll  100  without causing friction with the seal member  109 . 
     SUMMARY OF THE INVENTION 
     A first aspect of the present invention is a scroll compressor providing a fixed scroll comprising an end plate and an involute wrap provided on one face of the end plate, and an orbiting scroll comprising and end plate, an engagement part provided on one face of the end plate and accommodating an eccentric axle therein, and an involute wrap provided on the other face of the end face and forming a plurality of compression chambers by the combination with the involute wrap of the fixed scroll, wherein the end plate of the orbiting scroll is divided along the axial direction thereof into an involute wrap side end plate providing an involute wrap and an eccentric axle side end plate providing the engagement part, and furthermore, wherein a transmission mechanism is provided that permits movement of this involute wrap side end plate in the axial direction with respect to the eccentric axle side end plate but prevents movement in the radial or peripheral directions, and transmits the orbital movement of the eccentric axle side end plate to the involute wrap side end plate. 
     This scroll compressor efficiently transmits the rotation of the eccentric axle side end face to the involute wrap side end face by a transmission means, and can decrease drive loss. Furthermore, because there is no damage to the seal member, maintenance thereof is not necessary. 
     In particular, preferably the transmission mechanism comprises pin intermitting holes formed parallel to the axial direction on the external perimeter of the involute wrap side end plate and the eccentric axle side end plate and pins fit freely slidably into the pin interfitting holes from the involute wrap side end face or the eccentric side end face side, because the structure will be simplified. 
     A second aspect of the present invention is a scroll compressor characterized in an elastic member that presses the involute wrap side end face in the direction of the fixed scroll being installed between the involute wrap side end plate and the eccentric axle side end plate. 
     With this scroll compressor, the involute wrap side end face is continuously pressed against the fixed scroll by the elastic member. That is, a back-pressure applying mechanism that presses the end plate of the orbiting scroll against the fixed scroll side is provided on the orbiting scroll. Thereby, even during the beginning of the operation of the scroll compressor, no leakage of gas from the compression chamber occurs, and thus, the compression efficiency becomes high. Furthermore, with this scroll compressor, both the back-pressure applying mechanism and the transmission mechanism having an axially compliant structure are provided on the orbiting scroll side. When the scroll compressor wherein the fixed scroll as a whole has a floating structure and a back-pressure block is provided on the back face of the fixed scroll is compared to the above-described scroll compressor, in the above-described scroll compressor the high pressure compression chamber can be made compact, and thus the result is a housing having a reduced size. In particular, preferably an inexpensive flat spring can be used as the elastic member. 
     A third aspect of the invention is a scroll compressor characterized in sealed spaces being formed between the involute wrap side end plate and the eccentric axle side end plate, and furthermore, an introduction hole is formed in order to introduce working gas in the compression chamber to the involute wrap side end plate. 
     According to this scroll compressor, in addition to the elastic member, the involute wrap side end plate is pressed against the fixed scroll by the working gas in the compression chamber. 
     In particular, preferably two sealed spaces are formed, and the working gas in the middle-pressure compression chamber is introduced into one sealed space and the working gas in the high-pressure compression chamber is introduced into the other sealed space. 
     A fourth aspect of the invention is a scroll compressor having a high operation pressure applied, for example, to a refrigeration cycle using carbon dioxide as the working gas. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a longitudinal cross-sectional drawing showing a first embodiment of the scroll compressor according to the present invention. 
     FIG. 2 is an enlarged cross-sectional drawing of the orbiting scroll shown in FIG.  1 . 
     FIGS. 3A and 3B are cross-sectional drawings showing another example of an orbiting scroll, and show the orbiting scroll cut in mutually orthogonal directions. 
     FIGS. 3C,  3 D, and  3 E are drawings showing another example of the orbiting scroll, and are respectively a planar drawing showing the involute wrap side end plate, a planar drawing showing the eccentric axle side end plate, and a planar drawing showing the flat spring. 
     FIG. 4 is a schematic drawing showing a vapor compression type refrigeration cycle. 
     FIG. 5 is a Mollier chart for carbon dioxide. 
     FIG. 6 is a cross-sectional drawing the essential parts of a conventional scroll compressor. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Next, an embodiment of the scroll compressor of the present invention will be explained referring to the drawings. 
     First, please refer to FIG. 4 for the carbon dioxide cycle for the scroll compressor of the present invention. The carbon dioxide cycles shown in FIG. 4 applies, for example, to an air-conditioning system for an automobile. 
     In FIG. 4, reference numeral  1  denotes the scroll compressor that compresses carbon dioxide that is in a gaseous state. The scroll compressor  1  is driven by receiving drive power from a drive source such as an engine (not illustrated). Reference numeral  1   a  denotes a radiator such as a gas cooler that cools the carbon dioxide that has been compressed by the scroll compressor  1  by heat exchange with the external air. Reference numeral  1   b  denotes a pressure control valve that controls the pressure of the radiator  1   a  outlet side according to the temperature of the carbon dioxide on the radiator  1   a  outlet side. Reference numeral  1   c  is a metering device. The carbon dioxide is decompressed by the pressure control valve  1   b  and the metering device  1   c,  and the carbon dioxide changes to a gas-liquid two-phase state at low temperature and low pressure. Reference numeral  1   d  shows a vaporizer such as a heat sink that serves as an air-cooling mechanism in an automobile cabin. When the liquid-gas two-phase carbon dioxide at low temperature and low pressure is vaporized, that is, evaporated, in the vaporizer, the air in the automobile cabin is cooled by removing the latent heat of vaporization from the air in the automobile cabin. Reference numeral  1   e  denotes an accumulator that temporarily accumulates the gas-phase carbon dioxide. The scroll compressor  1 , the radiator  1   a,  the pressure control valve  1   b,  the metering device  1   c,  the vaporizer  1   d,  and the accumulator  1   e  are respectively connected by conduit  1   f  to form a closed system. 
     Next, a preferred embodiment of the above-described scroll compressor will be explained referring to FIG.  1 . The housing (casing)  1 A of the scroll compressor  1  is formed by a cup-shaped case body  2  and a front case (crankshaft case)  4  fastened thereto by a bolt  3 . The crankshaft  5  passes through the front case  4 , and is supported freely-rotatably in the front case  4  via a main bearing  6  and a sub-bearing  7 . The revolution of the automobile engine (not illustrated) is transmitted via a well-known electromagnetic clutch  32  to the crankshaft  5 . Moreover, reference numerals  32   a  and  32   b  respectively denote the coil and pulley of the electromagnetic clutch  32 . 
     Inside the housing  1 A, the orbiting scroll member  9  and the fixed scroll member  8  are disposed. Furthermore, an Oldham ring  27  is installed between the fixed scroll  8  and the orbiting scroll  9  that prevents autorotation of the orbiting scroll  9  and permits orbiting of the orbiting scroll  9  with respect to the fixed scroll  8 . 
     The fixed scroll  8  comprises an end plate  10  and an involute wrap  11  provided on the inside face thereof This end plate  10  is anchored to the case body  2  by a bolt  12 . In addition, on the outer peripheral face of the end plate  10 , a groove is formed for installing of an O-ring  14 , and an O-ring  14  is disposed in this groove. This O-ring  14  is in intimate contact with the inner peripheral face of the case body. Thereby, the inside of the case body  2  is divided into a low pressure chamber (intake chamber)  15  and a high pressure chamber (discharge chamber)  16 . Furthermore, on the end plate  10 , a discharge port  34  is formed, and a discharge valve  35  is installed for opening and closing this discharge port  34 . 
     The orbiting scroll  9  is formed by an end plate  17  comprising an involute wrap side end plate  13   a  and an eccentric axle side end plate  13   b,  and an involute wrap  18  provided on the inner face thereof. This involute wrap  18  has a form substantially identical to the involute wrap  11  of the fixed scroll  8 . The respective involute wraps  18  and  11  of the orbiting scroll  9  and the fixed scroll  8  are installed in the casing  1 A so as to be eccentric by the radius of the rotation orbit, and mesh by being offset by a rotation phase by 180°. Thereby, the side faces of the involute wraps  11  and  18  are in intimate contact at a plurality of locations. In addition, the tip seal (not illustrated) installed on the end plate of the involute wrap  11  of fixed scroll  8  is in intimate contact with the inner face of the involute wrap side end plate  13   a  of the orbiting scroll  9 . Thereby, a plurality of compression chambers  21   a  and  21   b  that are substantially point symmetrical with respect to the center of the involute wraps  11  and  18  are formed. Moreover, compression chambers  21   a  and  21   b  are middle pressure compression chambers while compression chamber  21   c  is a high pressure compression chamber. 
     Furthermore, on the center part of the external face of the eccentric axle side end plate  13   b  of the orbiting scroll  9 , a cylindrical engagement part (boss)  22  is formed. Inside this engagement part  22 , a drive bush  23  is accommodated freely rotatably via an orbiting bearing (drive bearing)  24  that also acts as a radial bearing. Furthermore, an eccentric axle  26  extending from the inner end of the crankshaft  5  is freely rotatably fit in a through hole  25  formed in the drive bush  23 . In addition, between the outer peripheral edge of the outer face of the end plate  17  of the orbiting scroll  9  and the front case  4 , a thrust ball bearing  19  is disposed in order to support the orbiting scroll  9 . 
     On the external periphery of the crankshaft  5 , a mechanical seal  28 , which is a well-known shaft seal, is disposed. This mechanical seal  28  is formed from a sheet ring  28   a,  anchored in the front case  4 , and a trailing ring  28   b  that rotates with the crankshaft  5 . This trailing ring  28   b  is pressed against the sheet ring  28   a  by the urging member  28   c.  Thereby, the trailing ring  28   b  slides with respect to the sheet ring  28   a  along with the rotation of the crankshaft  5 . 
     Below, the characteristic parts of the scroll compressor  1  are explained referring to FIG.  2 . 
     As briefly explained above, the end plate  17  of the orbiting scroll  9  is formed by an involute wrap side end plate  13   a  and an eccentric axle side end plate  13   b  which divide in the axial direction of the orbiting scroll  9 . The involute wrap side end plate  13   a  is provided with an involute projection  18  and the eccentric axle side end plate  13   b  is provided with a boss  22  that is an engagement part for the eccentric axle  26 . 
     The involute wrap side end plate  13   a  is attached freely movably on the eccentric axle side end plate  13   b  by a plurality of pins  40   a  on the fixed scroll  10  side. In addition, the rotation of the eccentric axle side end plate  13   b  can be efficiently transmitted to the involute wrap side end plate  13   a  via the plurality of pins  40   a.  More precisely, on the outer peripheral parts of the involute wrap side end plate  13   a  and the eccentric axle side end plate  13   b,  pin interfitting holes  40   b  for insertion of the plurality of the pins  40   a  are formed in parallel in the axial direction. The pins  40   a  are fit into these pin interfitting holes  40   b  freely slidably from the involute wrap side end plate  13   a  to the eccentric axle side end plate  13   b.  A transmission mechanism  40  is formed by these pins  40   a  and pin interfitting holes  40   b.  This transmission mechanism  40  permits the movement of the involute wrap side end plate  13   a  in the axial direction with respect to the eccentric axle side end plate  13   b,  and prevents the movements in the radial and peripheral directions. Furthermore, the orbiting movement of the eccentric axle side end plate  13   b  is transmitted to the involute wrap side end plate  13   a.  Moreover, in this structure, the pins  40   a  can also be inserted contrariwise from the eccentric axle side end plate  13   b  to the involute wrap side end plate  13   a.    
     In addition, a flat spring  41  is disposed between the external periphery of the involute wrap side end plate  13   a  and the external periphery of the eccentric axle side end plate  13   b.  This flat spring  41  is an elastic member that pushes the involute wrap side end plate  13   a  against the fixed scroll  8 . That is, the involute wrap side end plate  13   a  has an axial direction compliance support structure (floating structure) in its axial direction. 
     A first sealed space  43  and a second sealed space  44  are formed between the face  14   a  of the involute wrap side end plate  13   a  facing the eccentric axle side end plate  13   b  and the face  14   a  of the eccentric axle side end plate  13   b  facing the involute wrap side end plate  13   a.  More precisely, on the center part of the face  14   a  of the involute wrap side end plate  13   a  a convex part  43   a  is formed. On the center part of the face  14   b  of the eccentric axle side end plate  13   b,  a concave part  43   b  is formed such that a first sealed space  43  is formed having a certain width with respect to the convex part  43   a  of the involute wrap side end plate  13   a.  In addition, an annular concave part  44   a  is formed on the periphery of the convex part  43   a  of the involute wrap side end plate  13   a.  In contrast, on the eccentric axle side end plate  13   b  an annular convex part  44   b  is formed such that a second sealed space  44  is formed having a certain width with respect to the concave part  44   a  of the involute wrap side end plate  13   a.  Furthermore, on the external peripheral step of the convex part  43   a,  a first annular seal  45  having a U-shaped cross-section is formed. Thereby, the above-described sealed space  43  is formed. In addition, similarly, a second annular seal  46  having a U-shaped cross section is attached on the external peripheral step part of the concave part  44   a.  Thus, the above-described sealed space  44  is formed. 
     Furthermore, on the involute wrap side end plate  13   a,  a high pressure introduction hole  47  for communication between the first sealed space  43  and the high pressure part  21   c  of the compression chamber (refer to FIG. 1) and a middle pressure introduction hole  48  for communication between the second sealed space  44  and the middle pressure part  21   a  (refer to FIG. 1) of the compression chamber are formed. Moreover, the second sealed space  44  an the middle pressure introduction hole  48  need not be provided. 
     Below, the operation of the scroll compressor  1  will be explained. 
     Current passes through the coil  32   a  of the electromagnetic clutch  32 , and the rotation of the automobile engine is transmitted to the crankshaft  5 . Then the rotation of the crankshaft  5  is transmitted to the orbiting scroll member  9  via the orbiting drive mechanism comprising the eccentric axle  26 , and through hole  25 , the drive bush  23 , the orbiting bearing  24 , and the boss  22 . The orbiting scroll member  9  is prevented from autorotation by the Oldham ring  27 , which is an anti-rotation device, and moves in orbital rotation on a circular orbit whose radius is the eccentricity ρ of the eccentric axle  26 . Because the orbiting scroll member  9  and the fixed scroll member  8  are disposed eccentrically, the involute wraps  11  and  18  contact each other at a plurality of locations at which the vertical line extending the whole height of the involute wrap  11  of the fixed scroll member  8  is in contact with the vertical line extending the whole height of the involute wrap  18  of the orbiting scroll member  9 . Thereby, a plurality of compression spaces  21   a  and  21   b  are formed. When the orbiting scroll member  9  orbits, the contacting locations gradually move toward the centers of the involute wraps  11  and  18 . Thereby, as the orbiting scroll member  9  orbits, the compressed spaces  21   a  and  21   b  made by the contacting involute wraps  11  and  18  move towards the center of the involute wraps  11  and  18  while the volume of the compressed spaces  21   a  and  21   b  decreases. Accompanying the above, the working gas that flows to the intake chamber  15  through the intake opening (not illustrated) flows into the sealed space  21   a  from the outer terminal opening part (refer to arrow A in FIG. 1) between both of the involute wraps  11  and  18 , and reaches the center part  21   c  while being compressed. From here, the working gas passes through the discharge port  34  formed in the end plate  10  of the fixed scroll member  8 , pushes open the discharge valve  35 , and is discharged from the high pressure chamber  16 . Subsequently, the discharge gas flows out from the discharge opening  38 . Thereby, the working gas that is a fluid introduced from the intake chamber  15  due to the orbiting of the orbiting scroll member  9  is compressed in the sealed spaces  21   a  and  21   b,  and the obtained pressurized gas is discharged. The current flowing to the coil  32   a  of the electromagnetic clutch  32  is cut, and when the transmission of the rotational force to the crankshaft  5  ceases, the motion of the open-type compressor  1  is stopped. In addition, the when the current again runs to the coil  32   a  of the electromagnetic clutch  32 , the scroll compressor  1  restarts. 
     Moreover, one part of the working gas that is compressed to high pressure by being compressed in the high pressure part  21   a  of the compression chamber is introduced into the first sealed space  43  via the high pressure introduction hole  47 , and fills the space. The amount of high pressure working gas introduced into the first sealed space  43  is set so that the axial pressure applied from the first sealed space  43  to the involute wrap side end plate  13   a  is larger than the maximum value of the axial pressure applied from the compression chamber to the involute wrap side end plate  13   a.  Referring to FIG. 2 to explain this, the amount of the high pressure working gas introduced into the first sealed space  43  is such that the upward pressure applied to the involute wrap side end plate  13   a  from below is larger than the downward pressure applied to the involute wrap side end plate  13   a  from above. 
     Assuming that the area of the first sealed space  43  is R, and that the high pressure working gas from the high pressure introduction hole  47  is introduced at a discharge pressure Pd, then the force F 1  in the upward axial direction acting on the involute warp side end plate  13   a  from the first sealed space  43  is represented by the following equation: 
     
       
           F   1 =( Pd−Ps )×R 
       
     
     (where Ps is the intake pressure). 
     As explained above, in the involute wrap side end plate  13   a,  not only the upward force, but the pressure from the compression chamber to the involute wrap side end plate  13   a,  that is, the downward force F 2 , is applied simultaneously. Here, if the area R of the first sealed space  43  is set such that F 1 &gt;F 2 , then the involute wrap side end plate  13   a  contributes a back pressure from the first sealed space  43 , and is pressed against the fixed scroll  8 . The second sealed space  44  acts in the same manner as the first sealed space  43 . As a result, the tip seal (not illustrated) embedded in the end face of the involute wrap  11  of the fixed scroll  8  comes into intimate contact with the inside of the end plate  17  of the orbiting scroll  9 . Simultaneously, the tip seal (not illustrated) embedded in the end face of the involute wrap  18  of the orbiting scroll  9  also becomes in intimate contact with the inside of the end plate  10  of the fixed scroll  8 , and the leakage of the working gas from the compression spaces is prevented. 
     In the present embodiment, the rotation of the eccentric axle side end plate  13   b  of the orbiting scroll  9  is efficiently transmitted to the involute wrap side end plate  13   a  via the transmission means  40  comprising a plurality of pins  40   a  and pin holes  40   b  into which these pins  40   a  are inserted. 
     In addition, in particular during operation of the scroll compressor  1 , the pressure of the compressed working gas does not become sufficiently high. Due to this, the effect of the pack pressure application that presses the involute side end plate  13   a  against the fixed scroll  10  is low. However, even in this sort of case, the flat spring  41  continuously presses the involute wrap side end late  13   a  against the fixed scroll  8 , and thereby leakage of the working gas is reliably prevented, and thus the compression efficiency can be improved. 
     Furthermore, both the pack pressure application structure in which, in the orbiting scroll  9 , the involute wrap side end plate  13   a  of the orbiting scroll  9  is pressed against the fixed scroll  10  side and the axial compliance structure were used. The fixed scroll  10  as a whole was given a floating structure, and because the fixed scroll  10  is made to be in intimate contact with the orbiting scroll  9 , when the scroll compressor provided with back pressure block on the back face of the fixed scroll  10  is compared to the scroll compressor of the present embodiment, the scroll compressor of the present embodiment has the advantages that the high pressure chamber can be made smaller, and as a result the housing can be reduced in size. 
     FIGS. 3A and 3B are drawings for showing another example of the axial compliance support structure (floating structure) preferably used on the involute wrap side end plate  13   a.  These are cross-sectional drawings showing the orbiting scroll  9  when cut in mutually perpendicular directions. Between the involute wrap side end plate  13   a  shown in FIG.  3 C and the eccentric axle side end plate  13   b  shown in FIG. 3D, the ring-shaped flat spring  50  shown in FIG. 3E is provided as an elastic member. This flat spring  50  is disposed between the involute wrap side end plate  13   a  and the eccentric axle side end plate  13   b,  and then a plurality of bolts  51  are anchored by being inserted alternately in the peripheral direction from the involute wrap side end plate  13   a  and the eccentric axle side end plate  13   b.    
     More precisely, as shown in FIG. 3D, on the outside peripheral portion of the eccentric axle side end plate  13   b,  a plurality of screw holes  52  (four in this example), are formed at equal intervals along the peripheral direction. Furthermore, between a screw hole  52  and a screw hole  52 , a notch  52   a  is formed in order to prevent the screw holes  52  formed on the involute wrap side end plate  13   a  from being covered when the involute wrap side end plate  13   a  and the eccentric axle side end plate  13   b  are displaced over one another. 
     In addition, as shown in FIG. 3C, on the outside peripheral portion of the involute wrap side end plate  13   a,  a plurality of screw holes  53  (four in this example) are formed at equal intervals along the peripheral direction. Furthermore, between the screw hole  53  and screw hole  53 , a notch  54  is formed in order to prevent the screw holes  52  formed on the eccentric axle side end plate  13   b  from being covered when the involute wrap side end plate  13   a  and the eccentric axle side end plate  13   b  are disposed over one another. 
     Furthermore, as shown in FIG. 3E, on the flat spring  50 , through holes  55  are formed at eight equal intervals in the peripheral direction conforming to the screw holes  53  formed on the involute wrap side end plate  13   a  and the screw holes  52  formed on the eccentric axle side end plate  13   b.    
     The eight bolts  51  pass through the through holes  55  of the flat spring  50  from alternately opposite directions, that is, the bolts  51  are inserted alternating from the involute wrap side end plate  13   a  and then from the eccentric axle side end plate  13   b.  In other words, in each screw hole  52  of the eccentric axle side end plate  13   b,  the bolts  51  are inserted and engaged from the involute wrap side end plate  13   a.  Additionally, in the screw holes  53  of the involute wrap side end plate  13   a,  the bolts  51  are inserted and engaged from the eccentric axle side end plate  13   b.    
     By using this structure, the involute wrap side end plate  13   a  can be moved with respect to the eccentric axle side end plate  13   b  in the axial direction up to the limit of the flexible tolerance of the flat spring  50 . The rotation of the eccentric axle side end plate  13   b  is transmitted to the involute wrap side end plate  13   a  via the transmission mechanism comprising the bolts  51  and the flat spring  50 . 
     Moreover, in FIG. 3A to FIG. 3C, the sealed space and the high pressure introduction holes formed between the involute wrap side end plate  13   a  and the eccentric axle side end plate  13   b  are the same as those in FIG. 2, and are not illustrated. 
     Furthermore, in the above-described embodiment, a carbon dioxide cycle using carbon dioxide as a working gas is adopted in an open compressor, but the invention is not limited thereby, and can be applied to a vapor compression refrigeration cycle using a typical working gas such as Freon.