Abstract:
In the case where a radial fan is provided on the upper end side of a rotor to produce an air circulating flow containing refrigerant gas so as not to hinder the flow of lubricating oil in a motor chamber, by which a motor is cooled, in order to reduce the cost of the radial fan, the radial fan is constructed by combining a plurality of blades (fan blades)  242  formed radially in the range of approximately 180° opposed to an upper balancer  270  so as to have a height smaller than the height of the upper balancer  270 , and a fan cap  260  including a fan cover portion  262  covering the top faces of the blades  242  and an engagement portion  263  fixed to the upper end side of the rotor.

Description:
THCHINICAL FIELD  
         [0001]    The present invention relates to a scroll compressor used for a refrigerating cycle of an air conditioner or the like. More particularly, it relates to a scroll compressor provided with a radial fan that rotates together with a rotor in a closed vessel to restrain heat generation in a motor.  
         BACKGROUND ART  
         [0002]    A scroll compressor has a cylindrical closed vessel whose both ends are closed, and the closed vessel is arranged vertically. In the closed vessel, a refrigerant compressing section consisting of a combination of a fixed scroll and an orbiting scroll and a motor for driving the orbiting scroll are housed. The motor is also a heat source, and when it is operated in a closed space such as the closed vessel, the temperature rises rapidly. An excessive rise in temperature deteriorates component materials of the motor, so that the motor must be cooled.  
           [0003]    In the scroll compressor, as one of the methods for preventing an excessive temperature rise of the motor, a method described in Reference  1  (Japanese Patent Application Publication No. H07-305688) is known. This method is explained with reference to FIG. 10. A scroll compressor  1  has a cylindrical closed vessel  2  whose both ends are closed, and the interior of the closed vessel  2  is divided into a compression chamber  21  and a motor chamber  22  with a main frame  4  being held therebetween.  
           [0004]    In the compression chamber  21 , a refrigerant compressing section  3  consisting of a combination of a fixed scroll  31  and an orbiting scroll  32  is housed, and in the motor chamber  22 , a motor  6  having a rotational driving shaft  5  for orbiting the orbiting scroll  32  is housed. The closed vessel  2  is arranged vertically so that the axis thereof is substantially vertical, so that a bottom portion of the closed vessel  2  forms a storage portion for lubricating oil  9 .  
           [0005]    The fixed scroll  31  and the orbiting scroll  32  each have a scroll wrap formed so as to erect on an end plate, and are arranged in a state in which these scroll wraps are engaged with each other. In this state, the orbiting scroll  32  is rotated by the motor  6 , by which a crescent-shaped space formed by the wraps is moved from the outer periphery to the center while the volume is decreased. By utilizing this operation, low-pressure gas is sucked from the outer periphery side and high-pressure gas is discharged from a portion near the center.  
           [0006]    In order to restrain an excessive rise in temperature of the motor  6 , in Reference  1 , a pipe  23  is provided on the outside of the closed vessel  2  to cause the refrigerant compressing section  3  to communicate with a lower space  22   b  of the motor chamber  22 , by which high-pressure refrigerant gas produced in the refrigerant compressing section  3  is introduced into the lower space  22   b  of the motor chamber  22  via the pipe  23 .  
           [0007]    According to this configuration, the high-pressure refrigerant gas passes through a gap Ga between a stator  6   a  and a rotor  6   b  of the motor  6  and a gap Gb between the stator  6   a  and the closed vessel  2 , flowing toward an upper space  22   a  of the motor chamber  22  while cooling the motor  6 , and is delivered to a refrigerating cycle through a refrigerant discharge pipe  24  provided in the upper space  22   a.    
           [0008]    However, in the case of Reference  1 , there arise problems described below. The lubricating oil  9  stored under the motor chamber  22  is pumped up by a positive displacement pump or a centrifugal pump provided on the lower end side of the rotational driving shaft  5  along with the rotation of the rotor  6   b . After lubricating sliding portions such as a bearing of the main frame  4 , the lubricating oil  9  returns from the upper space  22   a  of the motor chamber  22  to the lower space  22   b  thereof passing through the gap between the stator  6   a  and the closed vessel  2 .  
           [0009]    Therefore, on the outer peripheral side of the stator  6   a , the high-pressure refrigerant gas flowing from the lower space  22   b  toward the upper space  22   a  and the lubricating oil flowing from the upper space  22   a  toward the lower space  22   b  collide with each other, so that the return of the lubricating oil  9  is hindered. Therefore, a sufficient amount of lubricating oil  9  is not supplied to the pump, so that poor lubrication of sliding portions may occur. Also, since the pipe  23  is laid on the outside of the closed vessel  2 , the piping cost is needed.  
           [0010]    To solve these problems, the applicant of the present invention has proposed a scroll compressor described in Japanese Patent Application Publication No. 2003-106272 as Reference  2 . In this scroll compressor, as communicating means for causing the upper space of motor chamber to communicate with the lower space thereof, first communicating means is provided between the stator of motor and the enclosed vessel, and second communicating means is provided in the rotor of motor or in the rotating shaft thereof. A radial fan that rotates together with the rotor is provided on an upper end ring of the rotor to directly introduce the high-pressure refrigerant gas produced in the refrigerant compressing section into the upper space of the motor chamber, by which the high-pressure refrigerant is circulated by convection using the radial fan to cool the motor.  
           [0011]    [0011]FIG. 11 shows an example of a radial fan  7  provided on an upper end ring  6   c  of the rotor. According to this configuration, some of high-pressure refrigerant is sucked from the lower space toward the upper space on the second communicating means side, and a circulation path for a flow from the upper space toward the lower space is formed on the first communicating means side, so that the motor can be cooled without a collision of the high-pressure refrigerant gas with the flow of lubricating oil.  
           [0012]    In a cage rotor, the end ring is usually manufactured by casting of aluminum. In Reference  2 , fan blades  7   a  of the radial fan  7  are formed integrally with the upper end ring  6   c , and a fan cover  8   a  for covering the top faces of the blades  7   a  is integrally formed on an upper balancer  8  installed to the upper end ring  6   c.    
           [0013]    According to this configuration, by installing the upper balancer  8  to the upper end ring  6   c , the radial fan  7  can be assembled. However, since the fan blade  7   a  and the upper balancer  8  have the same height, the fan blade  7   a  is higher than is necessary. Also, the mass of the balancer  8  must be increased according to the size of the fan blade  7   a , which increases the material cost.  
           [0014]    Furthermore, since the upper balancer  8  is formed integrally with the fan cover  8   a  for the fan blades  7   a , and thus the fan cover  8   a  is located just under a bearing section  4   a  (see FIG. 10) of the main frame  4 , a space having a height larger than the height of the upper balancer  8  must be secured between the bearing section  4   a  and the rotor  6   b , which poses a problem in that the axial length of the scroll compressor itself must accordingly be increased inevitably.  
           [0015]    To solve this problem, the applicant of the present invention has succeedingly proposed a scroll compressor described in Japanese Patent Application No. 2002-308007 as Reference  3 . One example of this proposal is explained with reference to FIG. 12. The height h of the fan blade  7   a  is made have the minimum height necessary for the air blowing capacity of the radial fan  7 , while the upper balancer  8  is made have a height p larger than h and is arranged so as to rotate along the outer periphery of the bearing section  4   a  of the main frame  4 .  
           [0016]    According to this configuration, the space between the bearing section  4   a  and the rotor  6   b  can be made narrower than the height of the upper balancer  8 . Therefore, the axial length of the scroll compressor itself can be made shorter, and also the radial fan  7  having a predetermined air blowing capacity can be obtained.  
           [0017]    However, in manufacturing the fan blades  7   a  and the upper balancer  8 , which have different heights as shown in FIG. 12, sintering is technically difficult to perform. Therefore, a cast product must be finished by cutting, which increases the manufacturing cost. A method can be used in which the radial fan  7  and the upper balancer  8  are manufactured separately by sintering. However, this method is unfavorable because the assembling man power increases, which also results in increased manufacturing cost.  
           [0018]    Also, in a synchronous motor using a permanent magnet rotor, unlike an induction motor having the cage rotor, the fan blades cannot be molded integrally with the end ring of rotor. Therefore, the fan blades of radial fan must be manufactured as a piece part by sintering or casting, which causes the cost to increase.  
         SUMMARY OF THE INVENTION  
         [0019]    Accordingly, an object of the present invention is to reduce the cost of a radial fan in the case where in order to prevent an excessive rise in temperature of a motor for driving an orbiting scroll in a refrigerant compressing section, the radial fan is provided on a rotor of the motor to circulate some of refrigerant gas in a motor chamber.  
           [0020]    To achieve the above object, a first invention of the present invention provides a scroll compressor in which the interior of a closed vessel is divided into a compression chamber on the upper side, which has a refrigerant compressing section, and a motor chamber on the lower side, which has a motor and is included in a part of a circulating path for refrigerant gas, by a main frame; in the motor chamber, there are provided, as means for causing a motor upper space to communicate with a motor lower space, first communicating means formed on the outer periphery side of a stator of the motor and second communicating means formed on the rotor side of the motor or on the rotor rotating shaft side; and a radial fan and a balancer that rotate together with the rotor are provided on the upper end side of the rotor, so that some of the refrigerant gas is sucked from the motor lower space via the second communicating means, and is discharged into the motor upper space so as to be circulated in the closed vessel by the radial fan, characterized in that the radial fan has a plurality of blades (fan blades) formed radially in the range of approximately 180° opposed to the balancer so as to have a height smaller than the height of the balancer, and a fan cap including a fan cover portion covering the top faces of the blades and an engagement portion fixed to the upper end side of the rotor.  
           [0021]    According to this configuration, a fan cover need not be formed integrally with either of the fan blades and the balancer. Therefore, the shapes of these elements may be simple, so that at least the balancer can be manufactured by sintering. Also, since the fan cap is fixed to the upper end side of the rotor together with the balancer, assembly can be accomplished easily.  
           [0022]    In order to prevent the refrigerant gas raised through the second communicating means from flowing out into the motor upper space without passing through the radial fan, the fan cap is preferably a partition plate for separating the second communicating means from the motor upper space. Thereby, the second communicating means and the motor upper space are caused to communicate with each other via the blades.  
           [0023]    According to a preferred mode of the first invention, the fan cap is formed by one substantially disk-shaped metallic sheet having an insertion hole for the rotor rotating shaft in the center thereof, almost a half of which is used as the fan cover portion and the remaining half of which is used as the engagement portion. According to this configuration, since the fan cap is formed by a product of metallic sheet, the material cost and fabrication cost are significantly lower than those of the conventional molded product.  
           [0024]    In order to respond to the case where the heights of the fan blade and the balancer are different from each other, the fan cap preferably has a connecting portion for integrally connecting the fan cover portion and the engagement portion in a step form so that the fan cover portion and the engagement portion are located at positions having different heights.  
           [0025]    According to this configuration, in the case where the rotor is a cage rotor, and the blades of the radial fan are formed integrally with an end ring of the cage rotor, while the balancer is formed separately, the engagement portion of the fan cap is fixed to the upper end portion of the rotor together with the balancer in a state of being held between the balancer and the upper end portion of the rotor.  
           [0026]    Also, in the case where the rotor is a cage rotor, and both of the blades of the radial fan and the balancer are formed integrally with an end ring of the cage rotor, the engagement portion of the fan cap is fixed to the upper end portion of the rotor together with the balancer in a state of being put on the balancer.  
           [0027]    Also, in the case where the rotor is a permanent magnet rotor, and the blades of the radial fan are formed integrally with an end plate installed to the magnet rotor, while the balancer is formed separately, the engagement portion of the fan cap is fixed to the upper end portion of the rotor together with the balancer and the end plate in a state of being held between the balancer and the end plate.  
           [0028]    Also, in the case where the rotor is a permanent magnet rotor, and both of the blades of the radial fan and the balancer are formed integrally with an end plate installed to the magnet rotor, the engagement portion of the fan cap is fixed to the upper end portion of the rotor together with the balancer in a state of being put on the balancer.  
           [0029]    To further reduce the cost, the first invention embraces a mode in which as the blades of the radial fan, fan blades are used which are formed by bending a metallic sheet, which has an insertion hole for the rotor rotating shaft in the center thereof, into a waveform in the range of approximately 180° in the circumferential direction with the insertion hole being the center.  
           [0030]    In this case, an engagement portion which is fixed to the upper end portion of the rotor is provided in the range of remaining 180° of the metallic sheet, and the engagement portion is formed with a split groove which divides the engagement portion into two, in the insertion hole for the rotor rotating shaft. Thereby, the work efficiency for installing the metallic sheet can further be improved.  
           [0031]    To achieve the above object, a second invention of the present invention provides a scroll compressor in which the interior of a closed vessel is divided into a compression chamber on the upper side, which has a refrigerant compressing section, and a motor chamber on the lower side, which has a motor and is included in a part of a circulating path for refrigerant gas, by a main frame; in the motor chamber, there are provided, as means for causing a motor upper space to communicate with a motor lower space, first communicating means formed on the outer periphery side of a stator of the motor and second communicating means formed on the rotor side of the motor or on the rotor rotating shaft side; and a radial fan and a balancer that rotate together with the rotor are provided on the upper end side of the rotor, so that some of the refrigerant gas is sucked from the motor lower space via the second communicating means and is discharged into the motor upper space so as to be circulated in the closed vessel by the radial fan, characterized in that the rotor is a permanent magnet rotor having an upper end plate and a lower end plate, and the radial fan consists of grooves formed radially on the lower surface side of the upper end plate so as to communicate with the second communicating means.  
           [0032]    According to this configuration, the radial fan can be obtained by simply installing the upper end plate to the rotor. In this case, the balancer can be formed integrally with the upper end plate in the range of approximately 180° opposed to the radial fan to further improve the assembling work efficiency.  
           [0033]    To achieve the above object, a third invention of the present invention provides a scroll compressor in which the interior of a closed vessel is divided into a compression chamber on the upper side, which has a refrigerant compressing section, and a motor chamber on the lower side, which has a motor and is included in a part of a circulating path for refrigerant gas, by a main frame; in the motor chamber, there are provided, as means for causing a motor upper space to communicate with a motor lower space, first communicating means formed on the outer periphery side of a stator of the motor and second communicating means formed on the rotor side of the motor or on the rotor rotating shaft side; and a radial fan and a balancer that rotate together with the rotor are provided on the upper end side of the rotor, so that some of the refrigerant gas is sucked from the motor lower space via the second communicating means and is discharged into the motor upper space so as to be circulated in the closed vessel by the radial fan, characterized in that the radial fan is formed by one metallic sheet having an insertion hole for the rotor rotating shaft in the center thereof, and has a fan blade portion including a plurality of radial grooves formed by bending the metallic sheet into a waveform in the range of approximately 180° in the circumferential direction with the insertion hole being the center so as to communicate with the second communicating means and an engagement portion formed so as to be fixed to the upper end side of the rotor together with the balancer in the range of remaining 180°.  
           [0034]    According to this configuration, the radial fan can be formed by a metal part produced by fabricating a part of metallic sheet into a waveform without using a sintering or casting process, and also can be assembled to the rotor easily. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0035]    [0035]FIG. 1 is a schematic sectional view showing a general configuration of a scroll compressor provided with a rotor in accordance with a first embodiment of the present invention;  
         [0036]    [0036]FIG. 2 is a sectional view taken along the line A-A of FIG. 1;  
         [0037]    [0037]FIG. 3 is an exploded perspective view of the rotor in accordance with the first embodiment;  
         [0038]    [0038]FIG. 4 is an exploded perspective view of a rotor in accordance with a second embodiment of the present invention;  
         [0039]    [0039]FIG. 5 is an exploded perspective view of a rotor in accordance with a third embodiment of the present invention;  
         [0040]    [0040]FIG. 6 is an exploded perspective view of a rotor in accordance with a fourth embodiment of the present invention;  
         [0041]    [0041]FIG. 7 is an exploded perspective view of a rotor in accordance with a fifth embodiment of the present invention;  
         [0042]    [0042]FIG. 8 is an exploded perspective view of a rotor in accordance with a sixth embodiment of the present invention;  
         [0043]    [0043]FIG. 9 is an exploded perspective view of a rotor in accordance with a seventh embodiment of the present invention;  
         [0044]    [0044]FIG. 10 is a schematic sectional view of a scroll compressor of a first conventional example;  
         [0045]    [0045]FIG. 11 is an exploded perspective view showing a construction of a radial fan provided by a scroll compressor of a second conventional example; and  
         [0046]    [0046]FIG. 12 is schematic sectional view showing a construction of a radial fan provided by a scroll compressor of a third conventional example. 
     
    
     DETAILED DESCRIPTION  
       [0047]    A scroll compressor  10  has a cylindrical closed vessel  100  whose both ends are closed and which is arranged vertically. The interior of the closed vessel  100  is divided into a compression chamber  110  on the upper side and a motor chamber  120  on the lower side with a main frame  130  being held therebetween.  
         [0048]    In the compression chamber  110 , a refrigerant compressing section  140  consisting of a combination of a fixed scroll  141  and an orbiting scroll  142  is housed. On an end plate of the fixed scroll  141 , a spiral fixed scroll wrap  143  is erected. Similarly, on an end plate of the orbiting scroll  142 , a spiral orbiting scroll wrap  144  is erected. The fixed scroll wrap  143  and the orbiting scroll wrap  144  are engaged with each other.  
         [0049]    On the back surface of the orbiting scroll  142 , a cylindrical bearing concave portion  145  is provided, and a crankshaft  152  of a motor rotational driving shaft  150  is connected to the bearing concave portion  145 . Between the orbiting scroll  142  and a main frame  130 , an Oldham&#39;s ring  146  is interposed to prevent the orbiting scroll  142  from rotating. Also, a refrigerant suction pipe  111  is inserted in the compression chamber  110  to draw a refrigerant (low-pressure refrigerant) having finished work from, for example, above the closed vessel  100  toward the refrigerant compressing section  140 .  
         [0050]    In the motor chamber  120 , an electric motor (hereinafter referred to as a motor)  200  having a rotational driving shaft  150  for driving the orbiting scroll  142  is housed. The interior of the motor chamber  120  is divided into a motor upper space  121  and a motor lower space  122  by the motor  200 , and a bottom portion of the motor lower space  122  forms a storage portion for lubricating oil  101 .  
         [0051]    The rotational driving shaft  150  includes a rotor rotating shaft  151  installed coaxially to a rotor  220  of the motor  200  and a crankshaft  152  that is provided at the tip end (upper end in FIG. 1) of the rotor rotating shaft  151  so as to be off-centered a predetermined distance with respect to the axis of the rotor rotating shaft  151 . In the rotational driving shaft  150 , a lubricating oil supply passage  153  is formed eccentrically to conduct the lubricating oil  101  to the tip end of the crankshaft  152 .  
         [0052]    In the motor lower space  122 , there is provided a subframe  160  that pivotally supports the lower end side of the rotor rotating shaft  151 . The rotor rotating shaft  151  is supported by two points of a rotor rotation bearing  131  formed on the main frame  130  and a bearing section  161  provided on the subframe  160 . The lower end side of the rotor rotating shaft  151  is supported by the subframe  160  so as to be immersed in the lubricating oil  101 .  
         [0053]    The scroll compressor  10  of this embodiment is of an internal high pressure type. The high-pressure refrigerant gas produced in the refrigerant compressing section  140  once enters the motor upper space  121  of the motor chamber  120  through a gas passage  132  formed on the outer periphery side of the fixed scroll  141  and the main frame  130 , and is delivered to a refrigerating cycle, not shown, through a refrigerant discharge pipe  123  provided in the motor upper space  121 .  
         [0054]    The motor  200  has a stator  210  arranged along the inner peripheral surface of the closed vessel  100  and the rotor  220  arranged rotatably on the inner peripheral surface of the stator  210  with a predetermined gap being provided therebetween. The rotor  220  has the rotor rotating shaft  151  in the center thereof. On the stator  210 , a coil  211  is wound to provide a rotating magnetic field to the rotor  220 .  
         [0055]    The motor upper space  121  and the motor lower space  122  are caused to communicate with each other by two first and second communicating means. In this example, the first communicating means is a notch groove  212  formed on the outer periphery side of the stator  210  between the stator  210  and the closed vessel  100 , and the second communicating means is a communicating hole  222  penetratingly formed in the axial direction of the rotor  220 . The arrangement and the number of notch holes  212  and communicating holes  222  can be set arbitrarily. The motor upper space  121  and the motor lower space  122  are also caused to communicate with each other by a gap that is present between the stator  210  and the rotor  220 .  
         [0056]    Although the communicating hole  222  is provided in the rotor  220  in FIGS. 1 and 2, it may be provided between a shaft insertion hole  221  in the rotor  220  and the rotor rotating shaft  151 . Specifically, a semicircular groove formed on the inner periphery side of the shaft insertion hole  221  and/or the outer periphery side of the rotor rotating shaft  151  may be used as the communicating hole  222 .  
         [0057]    Next, the construction of the rotor  220  will be described in detail with reference to FIG. 3. The rotor  220  in a first embodiment is a cage rotor. Specifically, the rotor  220  has a rotor body  230  formed by laminating ring-shaped electromagnetic steel sheets  231  while shifting through a predetermined angle, and end rings  240  and  250  are integrally molded at both ends of the rotor body  230 .  
         [0058]    As shown in FIG. 2, each of the electromagnetic steel sheets  231  is provided with many conductor forming holes  232  for forming cage conductors in the circumferential direction at predetermined intervals. By laminating the conductor forming holes  232  while shifting through a predetermined angle, a cage type slot holes  233  are formed in the rotor body  231 .  
         [0059]    The end rings  240  and  250  are formed integrally with conductors formed of, for example, aluminum that are cast in the slot holes  233 . In the central portion of the end ring  240 ,  250 , a circular concave portion  241  is formed, and each end portion of the communicating hole  222  is arranged in the concave portion  241 . The illustration of the circular concave portion on the lower end side is omitted for drawing convenience.  
         [0060]    On the upper end ring  240  on the upper side (motor upper space side  121 ) of the rotor  220 , a plurality of fan blades  242  constituting a radial fan are integrally formed. The fan blades  242  are arranged radially over a range of approximately 180° of the upper end ring  240 . Also, on the upper end ring  240 , guide pins  243  and  244  for fixing a fan cap  260  and a balancer  270 , described later, are provided in a pair at an interval of approximately 180°.  
         [0061]    The upper end ring  240  is provided with the fan cap  260  and the balancer (upper balancer)  270 . The fan cap  260  is formed by one substantially disk-shaped metallic sheet having an insertion hole  261  for the rotor rotating shaft  151  in the center thereof, and has a fan cover portion  262  for covering the top faces of the fan blades  242  and an engagement portion  263  engaged with the upper end ring  240 .  
         [0062]    The fan cover portion  262  is formed substantially over the semicircumference of the fan cap  260 , and the remaining semicircumference forms the engagement portion  263 . The fan cover portion  262  and the engagement portion  263  are connected to each other in a step form via connecting portions  264 ,  264 . In this example, the fan cap  260  is formed so that the fan cover portion  262  is located at a position one step higher than the engagement portion  263 .  
         [0063]    The connecting portion  264 ,  264  consists of a vertical plate having a height corresponding to the height of the fan blades  242 , and both ends thereof are connected to the fan cover portion  262  and the engagement portion  263  substantially at right angles. The engagement portion  263  is formed with guide holes  265 ,  265  in which the guide pins  243  and  244  of the upper end ring  240  are fitted.  
         [0064]    The upper balancer  270  consists of a C-shaped block arranged in the range of approximately 180° on the side opposite to the formation region of the fan blades  242  on the upper end ring  240 , and a sintered compact of, for example, brass powder can be used as the upper balancer  270 .  
         [0065]    The upper balancer  270  is formed so as to be higher than the fan blades  242  so that it has a mass equal to the sum of the balance mass inherent in the scroll compressor and the masses of the fan blades  242 . In both end portions of the upper balancer  270  are formed fixing holes  271 ,  271  into which the guide pins  243  and  244  are inserted from the downside.  
         [0066]    The fixing hole  271 ,  271  is provided as a through hole penetrating the upper balancer  270  from the lower end to the upper end. In this example, the fixing hole  271 ,  271  is formed so that the hole diameter on the lower end side is approximately equal to the diameter of the guide pin  243 ,  244  and the hole diameter on the upper end side is larger than that on the lower end side.  
         [0067]    In this example, the upper balancer  270  is fixed by being fitted on the guide pins  243  and  244  and then by staking the tip ends of the guide pins  243  and  244  from the upside of the fixing holes  271 ,  271 . For this purpose, the hole diameter on the upper end side is formed so as to be larger. Besides, the upper balancer  270  may be fixed using screw-type fasteners such as bolts.  
         [0068]    On the lower end ring  250  on the lower side (motor lower space side  122 ) the rotor  220 , a balancer  251  (hereinafter referred to as a lower balancer) is formed integrally. The lower balancer  251  is formed over a range of approximately 180° of the lower end ring  250 , and is formed so as to project by a predetermined height from the lower end surface of the lower end ring  250 . The upper balancer  270  and the lower balancer  251  are arranged so as to shift 180° from each other.  
         [0069]    According to this configuration, first, the fan cap  260  is placed on the upper end ring  240  so that the fan cover portion  262  covers the top faces of the fan blades  242 . For the positioning of the fan cap  260 , the guide holes  265 ,  265  in the engagement portion  263  are fitted on the guide pins  243  and  244  on the upper end ring  240 .  
         [0070]    Next, the upper balancer  270  is placed on the engagement portion  263  of the fan cap  260  by fitting the fixing holes  271 ,  271  in the upper balancer  270  on the guide pins  243  and  244 , and the tip ends of the guide pins  243  and  244  are staked. Thereby, the radial fan is provided on the rotor  220 .  
         [0071]    Referring again to FIG. 1, the operation of the scroll compressor provided with the radial fan is explained. When the motor  200  is started to operate the scroll compressor  10 , the low-pressure refrigerant that has finished work in the refrigerating cycle, not shown, is introduced to the outer periphery side of the refrigerant compressing section  140  through the refrigerant suction pipe  111 , and is compressed while moving between the scroll wraps  143  and  144  of the fixed scroll  141  and the orbiting scroll  142  from the outer periphery side to the center.  
         [0072]    The high-pressure refrigerant gas produced by the refrigerant compressing section  140  enters the motor upper space  121  of the motor chamber  120  through the gas passage  132 , and is delivered to the refrigerant cycle, not shown, through the refrigerant discharge pipe  123 . At this time, in the motor chamber  120 , the motor lower space  122  is made to have a negative pressure with respect to the motor upper space  121  by a centrifugal air blowing force of the radial fan consisting of the fan blades  242  that rotate together with the rotor  220 .  
         [0073]    Therefore, in the notch groove  212 , which is the first communicating means, an air flow directed from the motor upper space  121  to the motor lower space  122  is produced, and in the communicating hole  222 , which is the second communicating means, an air flow directed from the motor lower space  122  to the motor upper space  121  is produced.  
         [0074]    Thereby, some of the high-pressure refrigerant gas that enters the motor upper space  121  is circulated so as to go from the motor upper space  121  to the motor lower space  122  through the notch groove  212  on the outer periphery side and to return from the motor lower space  122  to the motor upper space  121  through the communicating hole  222  on the inner periphery side, by which the motor  200  is cooled.  
         [0075]    On the other hand, the lubricating oil  101  stored in the bottom portion of the closed vessel  100  is sucked upward through the lubricating oil supply passage  153  in the rotational driving shaft  150  by pumping means provided at the lower end of the rotational driving shaft  150 . After lubricating the bearing sliding portions of the main frame  130 , the lubricating oil  101  is returned to the motor upper space  121 . The lubricating oil  101  is returned to the bottom portion of the closed vessel  100  rapidly by being carried by the flow of high-pressure refrigerant gas going down through the notch groove  212  on the outer periphery side.  
         [0076]    As a second embodiment of the present invention, the fan cap  260  can also be applied to a rotor  320  having permanent magnets of a synchronous motor as shown in FIG. 4. In the permanent magnet rotor (magnet rotor)  320 , an upper end plate  340  and a lower end plate  350 , which are formed separately from a rotor body  330 , are installed on the upper end side and the lower end side of the rotor body  330 , respectively.  
         [0077]    The upper end plate  340  and the lower end plate  350  correspond to the upper end ring  240  and the lower end ring  250  of the above-described first embodiment, but they are different from each other in that the upper end plate  340  and the lower end plate  350  are not integral with the rotor body  330 .  
         [0078]    The rotor body  330  consists of a laminated body of electromagnetic steel sheets, and is formed with a shaft insertion hole  331 , through which the rotor rotating shaft  151  is inserted, in the center thereof. Around the shaft insertion hole  331 , there are provided communicating holes  332  that serve as the second communicating means for causing the motor upper space  121  to communicate with the motor lower space  122  (see FIG. 1). In this example, four communicating holes  332  are provided at intervals of 90° with the axis of the rotor  320  being the center.  
         [0079]    Also, in this example, the rotor body  330  is provided with six slot holes arranged at equal intervals in the circumferential direction, and a plate-shaped permanent magnet  333  is inserted in each of the slot holes. On the outer periphery side of the rotor body  330 , a plurality of pin insertion holes  334 , through which fixing pins  335  for holding the laminated body of electromagnetic steel sheets are inserted, are formed at equal intervals in the circumferential direction.  
         [0080]    On the upper end plate  340 , a plurality of fan blades  342  for radial fan are erected substantially over the semicircumference thereof. Also, the upper end plate  340  is provided with pin insertion holes  343 , through which the fixing pins  335  are inserted, the pin insertion holes  343  being arranged at equal intervals in the circumferential direction. The upper end plate  340  is integrally fixed to the rotor body  330  via the fixing pins  335 .  
         [0081]    As in the case of the above-described first embodiment, in the magnet rotor  320  as well, on the upper end plate  340 , there is provided a substantially C-shaped upper balancer  370  formed of, for example, a sintered compact, the upper balance  370  being arranged in the range of approximately 180° on the side opposite to the formation region of the fan blades  342 .  
         [0082]    The upper balancer  370  is integrally fixed to the rotor body  330  via the fixing pins  335  together with the fan cap  260  and the upper end plate  340 . For this purpose, the engagement portion  263  of the fan cap  260  and the upper balancer  370  are formed with pin insertion holes  365  and  371  through which the fixing pins  335  are inserted.  
         [0083]    Like the upper end plate  340 , the lower end plate  350  is also integrally fixed to the rotor body  330  via the fixing pins  335 . In this example, the lower end plate  350  and a lower balancer  351  are formed separately. The lower balancer  351  is fixed to the rotor body  330  via the fixing pins  335  together with the lower end plate  350 . The lower balancer  351  and the lower end plate  350  may be formed so as to be integral.  
         [0084]    One example of a procedure for assembling the magnet rotor  320  is explained. Assuming that the permanent magnets  333  are mounted in the rotor body  330  in advance, first, the fixing pins  335  are inserted under pressure into the pin insertion holes  334  in the rotor body  330 .  
         [0085]    Next, on the upper end side of the rotor body  330 , the pin insertion holes  343 ,  365  and  371  in the upper end plate  340 , the fan cap  260 , and the upper balancer  370  are fitted on projecting end portions of the fixing pins  335 . In this case, as in the case of the above-described first embodiment, the top faces of the fan blades  342  are covered by the fan cover portion  262  of the fan cap  260 , and the engagement portion  263  of the fan cap  260  is arranged between the upper end plate  340  and the upper balancer  370 .  
         [0086]    On the lower end side of the rotor body  330  as well, the lower end plate  350  and the lower balancer  351  are installed to projecting end portions of the fixing pins  335 . Then, both ends of the fixing pins  335  are staked. Thus, the radial fan can be assembled to the upper end plate  340  of the magnet rotor  320  at a low cost. The operation of the scroll compressor is the same as that in the above-described first embodiment.  
         [0087]    Next, a third embodiment shown in FIG. 5 is explained. FIG. 5 shows a rotor  420  only. This rotor  420  is a rotor for an induction motor, and the basic construction thereof may be the same as that of the rotor  220  shown in FIG. 3, which has been explained in the above-described first embodiment. Therefore, in the rotor  420 , the same reference numerals are applied to elements that are the same as or equivalent to those of the rotor  220 , and the explanation thereof is omitted.  
         [0088]    The third embodiment is characterized by the use of a fan plate  450  having the radial fan. Specifically, in the third embodiment, on the upper end ring  240  of a rotor body  430 , there are provided the guide pins  243  and  244  for integrally holding the fan plate  450  and the upper balancer  270 .  
         [0089]    The fan plate  450  is formed by a ring-shaped metallic sheet having an insertion hole  451  for the rotor rotating shaft  151  in the center thereof, and is provided with a plurality of blades (fan blades)  452  constituting the radial fan. The fan blades  452  are formed by bending the metallic sheet into a waveform in the range of approximately 180° in the circumferential direction with the insertion hole  451  being the center. In the range of remaining 180°, an engagement portion  453  that is fixed to the upper end portion of the rotor body  430  is provided. The engagement portion  453  is provided with a pair of pin insertion holes  454 ,  454  through which the guide pins  243  and  244  are inserted.  
         [0090]    According to this configuration, by fixing the fan plate  450  to the upper end ring  240  of the rotor body  430  together with the upper balancer  270 , the radial fan consisting of the fan blades  452  can be obtained. The fan blades  452  communicate with the communicating hole  222  serving as the second communicating means in a state of being fixed to the upper end ring  240 . Also, in this embodiment, the fan plate  450  is formed by pressing a metallic sheet. However, it may be formed by a resin sheet.  
         [0091]    Next, a fourth embodiment shown in FIG. 6 is explained. A rotor  520  in the fourth embodiment is a rotor for a permanent magnet motor, and the basic construction thereof may be the same as that of the rotor  320  shown in FIG. 4, which has been explained in the above-described second embodiment. Therefore, in the rotor  520 , the same reference numerals are applied to elements that are the same as or equivalent to those of the rotor  320 , and the explanation thereof is omitted.  
         [0092]    The fourth embodiment is characterized in that fan blades are not formed on the upper end plate  340  of a rotor body  530 , and instead a fan plate  550  is used together with the fan cap  260 .  
         [0093]    The fan plate  550  is formed by pressing a disk-shaped metallic sheet, and is provided with a shaft insertion hole  551 , through which the rotor rotating shaft  151  is inserted, in the center thereof. The fan plate  550  is formed with fan blades  552 , which are formed by bending the metallic sheet over the range of approximately 180° in the circumferential direction so that vertical faces and horizontal faces are arranged alternately. In the range of remaining 180°, an engagement portion  553  engaging with the upper end plate  340  is formed.  
         [0094]    In the engagement portion  553 , a plurality of pin insertion holes  554 , through which the fixing pins  335  projecting from the rotor body  530  are inserted, are formed at predetermined intervals in the circumferential direction. A part of the engagement portion  553  is formed of a slit groove  555 , which gives flexibility to the diameter of the shaft insertion hole  551  to decrease a gap between the shaft insertion hole  551  and the rotor rotating shaft  151  at the time of installation of the fan plate  550 , in the radial direction.  
         [0095]    The fan cap  260  is put on the fan plate  550 . In a state in which the top faces of the fan blades  552  are covered by the fan cover portion  262  of the fan cap  260 , the fan plate  550  is fixed to the upper end plate  340  of the rotor body  530  together with the upper balancer  370 , and communicates with the communicating holes  332  serving as the second communicating means in a state of being fixed. In some cases, the fan plate  550  may be formed by a resin sheet.  
         [0096]    Next, a fifth embodiment shown in FIG. 7 is explained. A rotor  620  in the fifth embodiment is a rotor for an induction motor, and the basic construction thereof may be the same as that of the rotor  220  shown in FIG. 3, which has been explained in the above-described first embodiment. Therefore, in the rotor  620 , the same reference numerals are applied to elements that are the same as or equivalent to those of the rotor  220 , and the explanation thereof is omitted.  
         [0097]    The fifth embodiment is characterized in that an upper balancer  642  is formed integrally with the upper end ring  240  of a rotor body  630  together with the fan blades  242 , and accordingly a fan cap  660  having a shape different from that of the fan cap  260  is used.  
         [0098]    Specifically, on the upper end ring  240 , the upper balancer  642 , which is arranged in the range of approximately 180° opposed to the fan blades  242 , is integrally formed so as to have a height larger than that of the fan blades  242 . The upper balancer  642  is provided with guide pins  644 ,  644  for installing the fan cap  660 . The entire mass of the upper balancer  642  is selected so as to be equal to the mass of the upper balancer  270  explained in the above-described first embodiment.  
         [0099]    The fan cap  660  is formed preferably by a metallic sheet having a shaft insertion hole  661  through which the rotor rotating shaft  151  is inserted, and has a fan cover portion  662  for covering the top faces of the fan blades  242  and an engagement portion  663  fixed to the upper end portion of the upper balancer  642 . The fan cover portion  662  and the engagement portion  663  are connected to each other via step portions  664 ,  664  so that the fan cover portion  662  is one step lower than the engagement portion  663 .  
         [0100]    According to the fifth embodiment, by simply fixing the fan cap  660  to the upper balancer  642 , the top faces of the fan blades  242  are covered by the fan cover portion  662  of the fan cap  660 , by which the radial fan using the fan blades  242  can be obtained.  
         [0101]    Next, a sixth embodiment shown in FIG. 8 is explained. A rotor  720  in the sixth embodiment is a rotor for a permanent magnet motor, and the basic construction thereof may be the same as that of the rotor  320  shown in FIG. 4, which has been explained in the above-described second embodiment. Therefore, in the rotor  720 , the same reference numerals are applied to elements that are the same as or equivalent to those of the rotor  320 , and the explanation thereof is omitted.  
         [0102]    The sixth embodiment is characterized in that an upper balancer  743  is formed integrally with the upper end plate  340  installed to a rotor body  730  together with the fan blades  342 , and accordingly a fan cap  750  having the same shape as that of the fan cap  660  in the above-described fifth embodiment is used.  
         [0103]    Specifically, the upper end plate  340  has a shaft insertion hole  741  through which the rotor rotating shaft  151  is inserted, and the upper balancer  743 , which is arranged in the range of approximately 180° opposed to the fan blades  342 , is integrally formed so as to have a height larger than that of the fan blades  342 . The entire mass of the upper balancer  743  is selected so as to be equal to the mass of the upper balancer  370  explained in the above-described second embodiment.  
         [0104]    The fan blades  342  and the upper balancer  743  are formed with pin insertion holes  744 , through which the end portions of the fixing pins  335  inserted under pressure in the rotor body  730  are inserted, at predetermined intervals to fix the upper end plate  340  to the rotor body  730 .  
         [0105]    The fan cap  750  is substantially the same as the fan cap  660 . It is formed preferably by a metallic sheet having a shaft insertion hole  751  through which the rotor rotating shaft  151  is inserted, and has a fan cover portion  752  for covering the top faces of the fan blades  342  and an engagement portion  753  fixed to the upper end portion of the upper balancer  743 .  
         [0106]    The fan cover portion  752  and the engagement portion  753  are connected to each other via step portions  754 ,  754  so that the fan cover portion  752  is one step lower than the engagement portion  753 . Also, the fan cover portion  752  and the engagement portion  753  are formed with pin insertion holes  755  at positions corresponding to the pin insertion holes  744  in the upper end plate  340  to fix the fan cap  750  to the rotor body  730 .  
         [0107]    In the sixth embodiment as well, after the upper end plate  340  is installed to the rotor body  730 , by simply fixing the fan cap  750  to the upper end plate  340 , the top faces of the fan blades  342  are covered by the fan cover portion  752  of the fan cap  750 , by which the radial fan using the fan blades  342  can be obtained.  
         [0108]    Next, a seventh embodiment shown in FIG. 9 is explained. A rotor  820  in the seventh embodiment is a rotor for a permanent magnet motor, and corresponds to a modification of the above-described sixth embodiment. Therefore, in the rotor  820 , the same reference numerals are applied to elements that are the same as or equivalent to those of the rotor  720 , and the explanation thereof is omitted.  
         [0109]    The seventh embodiment is characterized in that the radial fan is provided on the lower surface side (the surface side opposed to a rotor body  830 ) of the upper end plate  340  installed to the rotor body  830 .  
         [0110]    Specifically, the upper end plate  340  is formed into a disk shape having a shaft insertion hole  844 , through which the rotor rotating shaft  151  is inserted, in the center thereof preferably by sintering of metal powder. The upper end plate  340  is formed so as to have a large thickness, and on the lower surface side opposed to the rotor body  830 , a plurality of grooves  843  for radial fan are formed radially in the range of approximately 180°. The grooves  843  communicate with the communicating holes  332  serving as the second communicating means when the upper end plate  340  is fixed to the rotor body  830 .  
         [0111]    Also, on the upper surface side of the upper end plate  340 , an upper balancer  842  is provided in the range of approximately 180° on the opposite side opposed to the grooves  843  for radial fan. The upper balancer  842  is preferably formed integrally with the upper end plate  340 , but it may be formed separately and may be installed on the top surface of the upper end plate  340 .  
         [0112]    The upper end plate  340  is formed with pin insertion holes  845 , through which the end portions of the fixing pins  335  inserted under pressure in the rotor body  830  are inserted, at predetermined intervals to fix the upper end plate  340  to the rotor body  830 .  
         [0113]    According to the seventh embodiment, since the radial fan can be obtained by simply fixing the upper end plate  340  to the rotor body  830 , the aforementioned balancer cap is not needed, and thus the cost of radial fan can be reduced.  
         [0114]    Although the scroll compressor explained in the above-described embodiments is of an internal high pressure type in which the high-pressure refrigerant gas produced in the refrigerant compressing section is supplied to the refrigerating cycle via the motor chamber, the present invention can be applied to an internal low pressure type in which the low-pressure refrigerant returned from the refrigerating cycle is given to the refrigerant compressing section via the motor chamber. Also, although the balancer, the fan cap, and the like are fixed by staking the pins in the above embodiments, they may be fixed by using other fixing means such as bolts.  
         [0115]    The above is a description of preferred embodiments of the present invention given with reference to the accompanying drawings. The present invention is not limited to these embodiments. Various changes and modifications that will occur to a person skilled in the art having the ordinary technical knowledge who is engaged in the field of the scroll compressor within the scope of technical concept described in the appended claims are naturally embraced in the technical scope of the present invention.