Abstract:
A turbo compressor includes an impeller; compression stages having scroll chambers which introduce the refrigerant to the impeller or lead the refrigerant compressed by the rotation of the impeller to the outside; and an oil tank in which a heater is disposed and an lubricant oil is stored, and at least a part of the scroll chambers is disposed in the vicinity of the oil tank.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a turbo compressor and a refrigerator. More specifically, the present invention relates to a turbo compressor capable of compressing a fluid by a plurality of impellers and a refrigerator including the turbo compressor. 
         [0003]    Priority is claimed on Japanese Patent Application No. 2009-170191, filed Jul. 21, 2009, the content of which is incorporated herein by reference. 
         [0004]    2. Description of Related Art 
         [0005]    As a refrigerator for cooling or refrigerating a material to be cooled such as water, there is known a turbo refrigerator or the like including a turbo compressor which compresses and discharges the refrigerant by means of a compressing means equipped with an impeller or the like. In the compressor, when the compression ratio increases, the discharging temperature of the compressor rises and the volumetric efficiency declines. Thus, in the turbo compressor included in the turbo refrigerator or the like as described above, the compression of the refrigerant is often performed so as to be divided into a plurality of stages (for example, see PCT Japanese Translation Patent Publication No. 2008-506885). 
         [0006]    In such a turbo compressor, a spiral scroll chamber for leading the compressed refrigerant to the outside of the compressor or for introducing the refrigerant into the inside of the compressor to compress the refrigerant is disposed. Furthermore, the lubricant oil is supplied from an oil tank to sliding parts such as a bearing for rotatably supporting an impeller or the like. 
         [0007]    In the turbo compressor and the refrigerator of the related art as described above, when the operation is stopped for a long time, the refrigerant is condensed at the lower part in the scroll chamber. For this reason, before the operation of the compressor restarts, there is a need for an operation of discharging the condensed refrigerant liquid from a drain port disposed or the like under the scroll chamber to the outside, which becomes complicated. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention provides a turbo compressor and a refrigerator which can automatically discharge the refrigerant from the inside of the scroll chamber to rapidly restart the operation, even if the refrigerant is condensed in the scroll chamber for a long-term operation stop. 
         [0009]    According to a first aspect of the present invention, a turbo compressor relating to the present invention includes a case having sliding parts, an impeller which is connected to a shaft portion supported by the sliding part and rotates around an axis, a plurality of compression stages having scroll chambers which introduce the fluid into the impeller or leads the fluid compressed by the rotation of the impeller to the outside, and an oil tank in which a heating source is disposed and an lubricant oil to be supplied to the sliding part is stored, wherein at least a part of the scroll chambers is disposed in the vicinity of the oil tank. 
         [0010]    In the turbo compressor, at least a part of the scroll chambers is disposed in the vicinity of the oil tank with the heating source disposed thereon. For this reason, it is possible to preferably transmit the heat of the lubricant heated before the operation restart by the heating source oil from the wall surface of the oil tank to the wall surface of the scroll chamber. In addition, the fluid to be compressed, which has been condensed within the scroll chamber, can be heated by the heat. 
         [0011]    Thus, the work of discharging the condensed refrigerant liquid from the drain port or the like disposed under the scroll chamber to the outside is unnecessary, whereby the operation can restart without any particular operations. 
         [0012]    According to a second aspect of the present invention, in the turbo compressor relating to the present invention, at least a part of the scroll chamber is disposed under the oil surface of the lubricant oil to be stored in the oil tank. According to the turbo compressor, the heat of the heated lubricant oil can be more preferably transmitted to the scroll chamber. 
         [0013]    According to a third aspect of the present invention, a refrigerator relating to the present invention includes a condenser that cools and liquefies the compressed refrigerant; an evaporator which cools a material to be cooled by evaporating the liquefied refrigerant to take the vaporization heat from the material to be cooled; and a turbo compressor which compresses the refrigerant evaporated by the evaporator to supply the refrigerant to the condenser, wherein the above-mentioned compressor is used as the turbo compressor. 
         [0014]    The refrigerator exhibits the same working effects as the turbo compressor. 
         [0015]    According to the present invention, even if the refrigerant is condensed in the scroll chamber during operation stop, the refrigerant can be automatically discharged from the inside of the scroll chamber to rapidly restart the operation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a block diagram showing a schematic configuration of a turbo refrigerator relating to an embodiment of the present invention. 
           [0017]      FIG. 2  is a vertical sectional view of a turbo compressor included in the turbo refrigerator relating to an embodiment of the present invention. 
           [0018]      FIG. 3  is a sectional view taken from lines III-III in  FIG. 2 . 
           [0019]      FIG. 4  is a sectional view taken from lines IV-IV in  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    An embodiment of a turbo compressor and a refrigerator relating to the present invention will be described with reference to  FIGS. 1 to 4 . 
         [0021]    A turbo refrigerator (a refrigerator)  1  relating to the present embodiment is, for example, installed on a building or a factory so as to create the cooling water for air conditioning. As shown in  FIG. 1 , the turbo refrigerator  1  includes a condenser  2 , an economizer  3 , an evaporator  5  and a turbo compressor  6 . 
         [0022]    The condenser  2  is supplied with a compression refrigerant gas X 1 , which is a refrigerant (a fluid) such as R134a compressed in a gas state, and makes the compression refrigerant gas X 1  a refrigerant liquid X 2  by cooling and liquefying the compression refrigerant gas X 1 . As shown in  FIG. 1 , the condenser  2  is connected to the turbo compressor  6  via a flow path R 1  through which the compression refrigerant gas X 1  flows. In addition, the condenser  2  is connected to the economizer  3  via a flow path R 2  through which the refrigerant liquid X 2  flows. An expansion valve  7  for decompressing the refrigerant liquid X 2  is installed on the flow path R 2 . 
         [0023]    The economizer  3  temporarily stores the refrigerant liquid X 2  which has been decompressed in the expansion valve  7 . The economizer  3  is connected to the evaporator  5  via a flow path R 3  through which the refrigerant liquid X 2  flows. Furthermore, the economizer  3  is connected to the turbo compressor  6  via a flow path R 4  through which gaseous components X 3  of the refrigerant generated in the economizer  3  flow. An expansion valve  8  for further decompressing the refrigerant liquid X 2  is installed in the flow path R 3 . The flow path R 4  is connected to the turbo compressor  6  so as to supply the gaseous components X 3  to a second compression stage  23  described below which is included in the turbo compressor  6 . 
         [0024]    The evaporator  5  cools a material to be cooled, such as water, by evaporating the refrigerant liquid X 2  to take the vaporization heat from the material to be cooled. The evaporator  5  is connected to the turbo compressor  6  via a flow path R 5  through which a refrigerant gas X 4  generated by the evaporation of the refrigerant liquid X 2  flows. The flow path R 5  is connected to a first compression stage  22  described below which is included in the turbo compressor  6 . 
         [0025]    The turbo compressor  6  compresses the refrigerant gas X 4  to make it the compression refrigerant gas X 1 . As described above, the turbo compressor  6  is connected to the condenser  2  via the flow path R 1  through which the compression refrigerant gas X 1  flows. Furthermore, the turbo compressor  6  is connected to the evaporator  5  via the flow path R 5  through which the refrigerant gas X 4  flows. 
         [0026]    As shown in  FIGS. 2 to 4 , the turbo compressor  6  includes a case  11  with a plurality of sliding parts  10 , a plurality of compression stages  12 , and an oil tank  13  in which the lubricant oil LO is stored. 
         [0027]    The case  11  is divided into a motor housing  15 , a compressor housing  16  and a gear housing  17 , and those parts are connected to each other in a separable manner. On the motor housing  15 , an output shaft  18  which rotates around an axis O, and a motor  20 , which is connected to the output shaft  18  to drive the compression stage  12 , are disposed. The output shaft  18  is rotatably supported by a first bearing  21  fixed to the motor housing  15 . Herein, the sliding parts  10  include not only the first bearing  21  but a second bearing  26 , a third bearing  27 , a gear unit  28  or the like as described below. 
         [0028]    The compression stage  12  includes a first compression stage  22  which sucks and compresses the refrigerant gas X 4  (see  FIG. 1 ), and a second compression stage  23  which further compresses the refrigerant gas X 4  compressed in the first compression stage  22  to discharge the refrigerant gas X 4  as the compression refrigerant gas X 1  (see  FIG. 1 ). The first compression stage  22  is disposed on the compressor housing  16 . The second compression stage  23  is disposed on the gear housing  17 . 
         [0029]    The first compression stage  22  has a plurality of first impellers (impellers)  22   a , a first diffuser  22   b , a first scroll chamber (a scroll chamber)  22   c  and a suction port  22   d . The plurality of first impellers  22   a  is fixed to a rotational shaft (a shaft portion)  25 , is driven for rotation around the axis O by means of the motor  20 , and imparts the speed energy to the refrigerant gas X 4  which is supplied from a thrust direction to discharge the refrigerant gas X 4  in a radial direction. The first diffuser  22   b  compresses the refrigerant gas X 4  by converting the speed energy imparted to the refrigerant gas X 4  by the first impeller  22   a  into the pressure energy. The first scroll chamber (the scroll chamber)  22   c  leads the refrigerant gas X 4  compressed by the first diffuser  22   b  to the outside of the first compression stage  22 . The suction port  22   d  sucks the refrigerant gas X 4  to supply the same to the first impeller  22   a . The first diffuser  22   b , the first scroll chamber  22   c  and a part of the suction port  22   d  is formed by a first housing  22   e  surrounding the first impeller  22   a.    
         [0030]    A plurality of inlet guide vanes  22   g  for adjusting the suction capacity of the first compression stage  22  is installed in the suction port  22   d  of the first compression stage  22 . The respective inlet guide vanes  22   g  can rotate so that external areas from the flow direction of the refrigerant gas X 4  can be altered by means of a driving mechanism  22   i.    
         [0031]    In the first housing  22   e  which is the outer peripheral portion of the first impeller  22   a  in the first compression stage  22  and the suction port  22   d  at the upstream side thereof, a relay space  22   h , which forms a ring shape centered on the axis O, is dividedly formed. A driving mechanism  22   i  for driving the inlet guide vane  22   g  is housed inside the relay space  22   h.    
         [0032]    The relay space  22   h  communicates with the rear surface side of the inlet guide vane  22   g  in the suction port  22   d  via a slight gap  22   j . As a result, it is configured such that the pressure of the relay space  22   h  is always equal to that of the suction port  22   d.    
         [0033]    The second compression stage  23  includes a second impeller (an impeller)  23   a , a second diffuser  23   b , a second scroll chamber (a scroll chamber)  23   c  and an inlet scroll chamber (a scroll chamber)  23   d . The second impeller  23   a  imparts the speed energy to the refrigerant gas X 4 , which is compressed in the first compression stage  22  and is supplied from the thrust direction, to discharge the refrigerant gas X 4  in the radial direction. The second diffuser  23   b  compresses the refrigerant gas X 4  by converting the speed energy imparted to the refrigerant gas X 4  by the second impeller  23   a  to the pressure energy to discharge the refrigerant gas X 4  as the compression refrigerant gas X 1 . The second scroll chamber  23   c  leads the compression refrigerant gas X 1  discharged from the second diffuser  23   b  to the outside of the second compression stage  23 . The inlet scroll chamber  23   d  guides the refrigerant gas X 4  compressed in the first compression stage  22  to the second impeller  23   a . Herein, the second diffuser  23   b , the second scroll chamber  23   c  and a part of the inlet scroll chamber  23   d  is formed by a second housing  23   e  surrounding the second impeller  23   a.    
         [0034]    The second impeller  23   a  is fixed to the rotational shaft  25  such that the rear surface thereof is mated with that of the first impeller  22   a , and the rotational movement force from the output shaft  18  of the motor  20  is transmitted to the rotational shaft  25 , so that the rotational shaft  25  rotates around the axis O, whereby the second impeller  23   a  is driven for rotation. The second diffuser  23   b  is disposed around the second impeller  23   a  in the shape of a ring. 
         [0035]    The second scroll chamber  23   c  is connected to the flow path R 1  for supplying the condenser  2  with the compression refrigerant gas X 1  to supply the flow path R 1  with the compression refrigerant gas X 1  led from the second compression stage  23 . 
         [0036]    In addition, the first scroll chamber  22   c  of the first compression stage  22  and the inlet scroll chamber  23   d  of the second compression stage  23  are connected with each other via an outside piping (not shown) which is provided separately from the first compression stage  22  and the second compression stage  23 , whereby the refrigerant gas X 4  compressed in the first compression stage  22  is supplied to the second compression stage  23  via the outside piping. The above-mentioned flow path R 4  (see  FIG. 1 ) is connected to the outside piping, whereby the gaseous components X 3  of the refrigerant generated in the economizer  3  is supplied to the second compression stage  23  via the outside piping. 
         [0037]    The rotational shaft  25  is rotatably supported by the second bearing  26  fixed to the gear housing  17  and the third bearing  27  fixed to the compressor housing  16  in a rotatable manner with respect to the case  11 . 
         [0038]    In the gear housing  17 , an accommodation space S 1  is formed which accommodates a gear unit  28  for transmitting the driving force of the output shaft  18  to the rotational shaft  25 . 
         [0039]    The oil tank  13  is formed and disposed so as to extend from the lower part of the accommodation space S 1  to the lower part of the compressor housing  16 . The first scroll chamber  22   c , the second scroll chamber  23   c  and the lower part sides of the inlet scroll chamber  23   d  are disposed so as to be lower than the oil surface L of the lubricant oil LO stored in the oil tank  13 . 
         [0040]    A heater (a heating source)  30  for heating the lubricant oil LO to a prescribed temperature is disposed in the oil tank  13 . 
         [0041]    The gear unit  28  includes a low speed gear  31  fixed to the output shaft  18  of the motor  20 , and a high speed gear  32  which is fixed to the rotational shaft  25  and is engaged with the low speed gear  31 . In addition, the rotational movement force of the output shaft  18  of the motor  20  is transmitted to the rotational shaft  25  such that the revolution count of the rotational shaft  25  increases with respect to the revolution count of the output shaft  18 . 
         [0042]    Next, the operations of the turbo refrigerator  1  and the turbo compressor  6  relating to the present embodiment will be described. 
         [0043]    First of all, along with the operation start of the turbo refrigerator  1  and the turbo compressor  6 , the lubricant oil LO is supplied from the oil tank  13  to the sliding parts  10  by means of an oil pump (not shown). Then, the motor  20  is driven, so that the rotational movement force of the output shaft  18  of the motor  20  is transmitted to the rotation shaft  25  via gear unit  28 . As a result, the first compression stage  22  and the second compression stage  23  are driven for rotation. 
         [0044]    When the first compression stage  22  is driven for rotation, the suction port  22   d  of the first compression stage  22  enters a negative pressure state, whereby the refrigerant gas X 4  from the flow path R 5  flows in the first compression stage  22  via the suction port  22   d . At this time, the suction capacity is suitably adjusted by means of the inlet guide vane  22   g.    
         [0045]    The refrigerant gas X 4 , which has flowed in the first compression stage  22 , flows in the first impeller  22   a  from the thrust direction, is imparted with the speed energy by the first impeller  22   a  and is discharged in the radial direction. 
         [0046]    The speed energy of the refrigerant gas X 4  discharged from the first impeller  22   a  is converted to the pressure energy by the first diffuser  22   b , so that the refrigerant gas X 4  is compressed. The refrigerant gas X 4  discharged from the first diffuser  22   b  is led to the outside of the first compression stage  22  via the first scroll chamber  22   c.    
         [0047]    In addition, the refrigerant gas X 4  led to the outside of the first compression stage  22  is supplied to the second compression stage  23  via the outside piping. 
         [0048]    The refrigerant gas X 4  supplied to the second compression stage  23  flows in the second impeller chamber  23   a  from the thrust direction via the inlet scroll chamber  23   d  and is discharged in the radial direction imparted with the speed energy by the second impeller  23   a.    
         [0049]    The speed energy of the refrigerant gas X 4  discharged from the second impeller  23   a  is converted to the pressure energy by the second diffuser  23   b , whereby the refrigerant gas X 4  is further compressed and becomes the compression refrigerant gas X 1 . 
         [0050]    The compression refrigerant gas X 1  discharged from the second diffuser  23   b  is led to the outside of the second compression stage  23  via the second scroll chamber  23   c.    
         [0051]    In addition, the compression refrigerant gas X 1  led to the outside of the second compression stage  23  is supplied to the condenser  2  via the flow path R 1 . 
         [0052]    In a case where R134a or the like is used as the refrigerant liquid X 2 , since the condensation temperature is 30° C. to 40° C., when the turbo refrigerator  1  is stopped for a long time, the refrigerants remaining as the gas in the first scroll chamber  22   c , the second scroll chamber  23   c  and the inlet scroll chamber  23   d  are condensed in the lower part thereof. 
         [0053]    When the operation restarts, the lubricant oil LO stored in the oil tank  13  is heated to the condensation temperature or more of the refrigerant by means of the heater  30 . As a result, the heat of the heated lubricant oil LO is transferred from the wall surface of the oil tank  13  to the respective wall surfaces of the first scroll chamber  22   c , the second scroll chamber  23   c  and the inlet scroll chamber  23   d , so that the refrigerant, which was condensed in the chamber, is heated. Thus, the refrigerant is evaporated and becomes gas again. 
         [0054]    According to the turbo refrigerator  1  and the turbo compressor  6 , the first scroll chamber  22   c , the second scroll chamber  23   c  and the lower part of the inlet scroll chamber  23   d  are disposed in the vicinity of the oil tank  13 . For that reason, when the turbo compressor  6  starts, by heating the lubricant oil LO stored in the oil tank  13  with the heater  30 , the refrigerants, which are condensed in the first scroll chamber  22   c , the second scroll chamber  23   c  and the inlet scroll chamber  23   d , are heated and evaporated, whereby the refrigerants can be automatically discharged from the chamber. 
         [0055]    At this time, the first scroll chamber  22   c , the second scroll chamber  23   c  and the lower part of the inlet scroll chamber  23   d  are disposed at the part lower than the oil surface L of the lubricant oil LO which is stored in the oil tank  13 . Thus, the heat of the heated lubricant oil LO can be further preferably transmitted. 
         [0056]    Furthermore, the technical scope of the present invention is not limited to the above-mentioned embodiment, but various modifications can be added without departing from the gist of the present invention. 
         [0057]    For example, in the above-mentioned embodiments, although the configuration including the two compression stages (the first compression stage  22  and the second compression stage  23 ) has been described, the present invention is not limited thereto, but a configuration including three or more compression stages may be adopted. 
         [0058]    In addition, the turbo compressor, in which the motor housing  15 , the compressor housing  16 , and the gear housing  17  are each dividedly formed as the case  11 , has been described. However, the present invention is not limited thereto, but, for example, a configuration, in which the motor is disposed between the first compression stage and the second compression stage, may be adopted. 
         [0059]    While preferred embodiments of the invention have been described and illustrated above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit or scope of the present invention. Accordingly, the invention is not to be considered as being limited by the foregoing description, and is only limited by the scope of the appended claims.