Patent Publication Number: US-7717686-B2

Title: Two stage compressor having rotary and scroll type compression mechanisms

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a compressor and, more particularly, to a compressor provided with two compression mechanisms of a rotary type compression mechanism and a scroll type compression mechanism. 
   2. Description of the Related Art 
   A compressor provided with two compression mechanisms of a rotary type compression mechanism and a scroll type compression mechanism has been proposed. For example, Japanese Patent Laid-Open No. 5-87074 discloses a two-stage compressor in which an electric motor is provided in a single hermetic housing and two compression mechanisms each driven by the rotating shaft of the electric motor are provided; one of these two compression mechanisms is made a rotary type compression mechanism and the other thereof is made a scroll type compression mechanism; and one of the two compression mechanisms is on the low stage side and the other thereof is on the high stage side. Japanese Patent Laid-Open No. 5-87074 describes that in this two-stage compressor, the low stage-side compression mechanism is preferably of a rotary type. According to this two-stage compressor, the low stage-side compressor compresses gases from a low pressure to an intermediate pressure, and the high stage-side compressor compresses gases from the intermediate pressure to a high pressure. Therefore, the drawback of individual compressor is overcome, and a compressor small in size but high in performance can be provided as compared with the case where a rotary type compression mechanism or a scroll type compression mechanism is used singly to compress gases from a lower pressure to a high pressure. 
   The rotary type compression mechanism has a rotor performing eccentric rotating motion in a cylinder and a blade reciprocating in a groove in the cylinder while the tip end thereof is in contact with the rotor. The blade partitions a space formed by the cylinder and the rotor into a suction chamber and a compression chamber. This blade must be lubricated because of its sliding motion performed when the blade reciprocates in the groove. Therefore, the oil level of lubricating oil is controlled so that the cylinder is immersed in the lubricating oil stored in an oil reservoir provided in the bottom part of the compressor. 
   From the viewpoint of energy saving, an inverter is used for the rotating speed control of a compressor. The inverter can be operated in a wide range from a low rotational speed to a high rotational speed. In the case of low rotational speed, the quantity of lubricating oil drawn up from the oil reservoir to lubricate the compression mechanisms is small, but in the case of high rotational speed, a large quantity of lubricating oil is drawn up. That is to say, the use of the inverter changes the height of oil level depending on the rotational speed of the compressor. 
   Also, in recent years, from the viewpoint of the preservation of global environment, the use of carbon dioxide (CO 2 ), which is one of natural refrigerants, as a refrigerant gas has been studied. If CO 2  is used as a refrigerant gas, the pressure on the high pressure side of a heat pump cycle increases and exceeds the critical pressure. If CO 2  in a supercritical pressure state is used, the dissolution amount of lubricating oil increases, so that the height of oil level is liable to change depending on the operating condition. In particular, in an operating condition in which the circulation amount of refrigerant gas is large, the quantity of lubricating oil in the oil reservoir decreases, and the oil level may become lower than the cylinder. At this time, the lubricating oil is not supplied to between the blade and the groove. Therefore, the mechanical efficiency is decreased by the increase in friction between the blade and the cylinder (groove), and also the reliability may be decreased by the friction. Also, the refrigerant gas flows in between the suction chambers or the compression chambers from the back surface of blade, which also poses a problem of decreased compressing efficiency. 
   SUMMARY OF THE INVENTION 
   The present invention has been accomplished to solve the above-described technical problems, and accordingly an object thereof is to provide a compressor capable of feeding lubricating oil to a blade of a rotary type compression mechanism even if the oil level in an oil reservoir lowers. 
   To achieve the above object, the present invention provides a compressor including a hermetic housing in which lubricating oil is stored in the bottom part thereof; a low stage-side rotary type compression mechanism provided in the hermetic housing and having a rotor, and a cylinder for holding the blade reciprocating with the rotation of the rotor while the tip end thereof is in contact with the rotor; a high stage-side scroll type compression mechanism provided in the hermetic housing to suck and compress refrigerant gas compressed by the low stage-side rotary type compression mechanism; a drive shaft connecting the low stage-side rotary type compression mechanism and the high stage-side scroll type compression mechanism to each other and having an oil feeding hole in the axial direction; an electric motor for driving the low stage-side rotary type compression mechanism and the high stage-side scroll type compression mechanism via the drive shaft; a lubrication pump for feeding the lubricating oil to the high stage-side scroll type compression mechanism via the oil feeding hole; and an oil feeding path for feeding the lubricating oil, which is fed to the high stage-side scroll type compression mechanism, toward the blade of the low stage-side rotary type compression mechanism. 
   The compressor in accordance with the present invention feeds the lubricating oil, which is drawn up by the lubrication pump and fed to the high stage-side scroll type compression mechanism during operation, toward the blade. Therefore, the compressor in accordance with the present invention can feed the lubricating oil to the blade surely even if the oil level in the oil reservoir lowers during operation. 
   In the compressor in accordance with the present invention, the oil feeding path is preferably configured so that the lubricating oil drops freely and is fed toward the blade. According to this oil feeding path, the lubricating oil fed to the high stage-side scroll type compression mechanism can be fed to the blade through the shortest distance. Therefore, the dissolution of lubricating oil in the refrigerant gas can be kept to the minimum. Also, according to this oil feeding path, a member for guiding the lubricating oil coming from the high stage-side scroll type compression mechanism to the blade need not be provided separately. 
   In the compressor in accordance with the present invention, the oil feeding path is preferably configured so that the lubricating oil is fed toward a penetrating hole formed in the cylinder so as to house an elastic body for pressing the blade toward the rotor and to penetrate in the rotation axis direction of the rotor. The lubricating oil fed toward the penetrating hole is sucked toward the tip end direction of the blade by the influence of differential pressure with the interior of rotor, so that the blade can be lubricated smoothly. Also, excess lubricating oil passes through the penetrating hole, and is dropped into the oil reservoir in the bottom part of the hermetic housing. Therefore, an increase in oil circulation rate (the quantity of oil circulating together with the refrigerant gas, OCR) caused by the raised excess lubricating oil can be prevented. 
   In the compressor in accordance with the present invention, the oil feeding path preferably has a shield for restraining the contact of the lubricating oil flowing in the oil feeding path with the refrigerant gas existing in the hermetic housing, so as to prevent an increase in OCR. 
   In the compressor in accordance with the present invention, in the case where the low stage-side rotary type compression mechanism is formed by a first rotary type compression mechanism positioned on the upper side and a second rotary type compression mechanism positioned on the lower side of the first rotary type compression mechanism, the oil feeding path has only to be configured so as to feed the lubricating oil, which is fed to the high stage-side scroll type compression mechanism, toward the blade of the first rotary type compression mechanism. For the second rotary type compression mechanism positioned on the lower side, the lubricating oil can be fed to the blade stably by adjusting the oil level of lubricating oil, but for the first rotary type compression mechanism positioned on the upper side, the lubricating oil cannot be fed stably. Therefore, the lubricating oil is fed from the high stage-side scroll type compression mechanism toward the blade of the first rotary type compression mechanism positioned on the upper side. 
   As described before, in the case where the refrigerant gas is CO 2 , the dissolution amount of lubricating oil increases, so that the height of oil level is liable to change depending on the operating condition. Therefore, the present invention is preferably applied to a compressor in which CO 2  is used as the refrigerant gas. 
   According to the present invention, even if the oil level in the oil reservoir lowers during operation, the lubricating oil can be fed to the blade surely. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a sectional view showing a construction of a compressor to which the present invention is applied; 
       FIG. 2  is a plan view showing a construction of a rotary type compression mechanism on the low stage side; 
       FIG. 3  is a transverse sectional view of a positive displacement lubrication pump; 
       FIG. 4  is a sectional view showing a construction of another compressor to which the present invention is applied; 
       FIG. 5  is a sectional view showing a twin rotary type compression mechanism; and 
       FIG. 6  is a schematic view showing an arrangement example of blades of a twin rotary type compression mechanism. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   First Embodiment 
   Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. 
     FIG. 1  is a sectional view showing the construction of a compressor  1  in accordance with a first embodiment. 
   In the compressor  1 , a low stage-side rotary type compression mechanism  3  is provided in the lower part of a hermetic housing  2 , and a high stage-side scroll type compression mechanism  4  is provided in the upper part therein. Also, in the central part of the hermetic housing  2 , an electric motor  21  is provided between the low stage-side rotary type compression mechanism  3  and the high stage-side scroll type compression mechanism  4 . The electric motor  21  includes a stator  22  and a rotor  23 . The rotor  23  is integrally connected with a crankshaft  24 . The lower end part of the crankshaft  24  forms a crankshaft  25  for the low stage-side rotary type compression mechanism  3 , and the upper end part thereof forms a crankshaft  26  for the high stage-side scroll type compression mechanism  4 . In the outer peripheral surface of the stator  22 , cut parts  22 C are formed. In portions in which the cut parts  22 C are formed, spaces are formed between the stator  22  and the hermetic housing  2 . Usually, the plurality of cut parts  22 C are formed at predetermined intervals in the outer periphery direction of the stator  22 . 
   Also, in the bottom part of the hermetic housing  2 , a predetermined amount of lubricating oil  27  is stored. The lubricating oil  27  is fed to predetermined lubrication locations of the low stage-side rotary type compression mechanism  3  and the high stage-side scroll type compression mechanism  4  via an oil feeding hole  11  formed in the axial direction of the crankshaft  24  by a positive displacement lubrication pump  60  provided in the lower end part of the crankshaft  25 . 
   As the low stage-side rotary type compression mechanism  3 , a general rotary type compression mechanism is used which has a cylinder chamber  31 , and includes a cylinder body  30  fixed to the hermetic housing  2 , an upper bearing  32  and a lower bearing  33  provided on top of and beneath the cylinder body  30 , respectively, a rotor  34  fitted in a crank part  25 A of the crankshaft  25  and rotated slidingly in the cylinder chamber  31 , a discharge cover  36  forming a discharge cavity  35 , and a blade  38  (refer to  FIG. 2 ) partitioning the cylinder chamber  31 . As shown in  FIG. 2 , the blade  38  is disposed in a slit  39  formed in the cylinder body  30 . The slit  39  is formed along the radial direction of the cylinder body  30  so as to have an approximately uniform width, and one end thereof is open to the cylinder chamber  31 . At the other end of the slit  39 , a broached hole  39 H is formed. The broached hole  39 H penetrates the cylinder body  30  in the rotation axis direction of the rotor  34 . A spring S is disposed in the broached hole  39 H to press the blade  38  toward the rotor  34 . The blade  38  reciprocates along the radial direction with the rotation of the rotor  34  while the tip end thereof is in contact with the outer periphery of the rotor  34 . 
   In the low stage-side rotary type compression mechanism  3 , refrigerant gas sucked into the cylinder chamber  31  via a suction pipe  37  connected to an accumulator, not shown, is compressed to an intermediate pressure by the rotation of the rotor  34 , and then is discharged into the discharge cavity  35  and is further discharged into the hermetic housing  2  through a discharge opening provided in the discharge cover  36 . 
   The refrigerant gas having the intermediate pressure discharged into the hermetic housing  2  flows into an upper space of the hermetic housing  2  through an air gap and the like of the electric motor  21 , and is sucked into the high stage-side scroll type compression mechanism  4 . 
   The high stage-side scroll type compression mechanism  4  includes a bearing  40  having a bearing part  41  for supporting the crankshaft  26  from the outer periphery and a fixing plate  42  for fixing the bearing  40 . The fixing plate  42  is fixed to the hermetic housing  2 . The bearing  40  is formed with an oil exhaust hole  40 H. The oil exhaust hole  40 H is formed so as to be directed from the central part to the outer peripheral part of the bearing  40 , and extends downward in the figure in the end part of the outer peripheral part. The fixing plate  42  is also formed with an oil exhaust hole  42 H. The oil exhaust hole  42 H is connected to the oil exhaust hole  40 H. The lubricating oil  27  supplied to the high stage-side scroll type compression mechanism  4  as described later is collected in a concave part of the bearing  40 , and is exhausted from this concave part to the lower part of the hermetic housing  2  through the oil exhaust hole  40 H and the oil exhaust hole  42 H. 
   For the compressor  1  in accordance with this embodiment, the positions of the oil exhaust hole  42 H and the cut part  22 C coincide with each other in the vertical direction. Further, the positions of the cut part  22 C and the portion in which the blade  38  of the low stage-side rotary type compression mechanism  3  is disposed coincide with each other in the vertical direction. Therefore, the lubricating oil  27  exhausted from the oil exhaust hole  42 H freely drops and passes through a space between the stator  22  and the hermetic housing  2 , which is formed by the cut part  22 C, and then is dripped toward the blade  38  of the low stage-side rotary type compression mechanism  3 . 
   Also, the high stage-side scroll type compression mechanism  4  includes a fixed scroll  43  and an orbiting scroll  44  for forming a pair of compression chambers  45  by being engaged with each other with the phase being shifted, a drive bush  46  connecting the orbiting scroll  44  to a crank part  26 A formed at the shaft end of the crankshaft  26  to revolve the orbiting scroll  44 , and an Oldham&#39;s ring  47  provided between the orbiting scroll  44  and the bearing  40  to revolve the orbiting scroll  44  while preventing the rotation thereof. 
   Further, the high stage-side scroll type compression mechanism  4  includes a discharge valve  48  provided on the back surface of the fixed scroll  43  and a discharge cover  50  fixed on the back surface of the fixed scroll  43  to form a discharge chamber  49  between the discharge cover  50  and the fixed scroll  43 . 
   In the high stage-side scroll type compression mechanism  4 , a discharge pipe  51  is connected to the discharge chamber  49 , so that the refrigerant gas having been compressed to high temperature and pressure by the procedure described below is discharged to the outside of the compressor  1 . 
   In the high stage-side scroll type compression mechanism  4 , the refrigerant gas compressed to the intermediate pressure by the low stage-side rotary type compression mechanism  3  and discharged into the hermetic housing  2  is sucked into the paired compression chambers  45  through a suction opening  52 . The paired compression chambers  45  are moved to the center side while the volume thereof is decreased by the revolution of the orbiting scroll  44 , and join together to form one compression chamber  45 . During this time, the refrigerant gas is compressed from the intermediate pressure to a high pressure (discharge pressure), and is discharged into the discharge chamber  49  through a discharge port  53  formed in the central part of the fixed scroll  43 . This high temperature and pressure refrigerant gas is discharged to the outside of the compressor  1  via the discharge pipe  51 . 
   As shown in  FIG. 3 , the positive displacement lubrication pump  60  forms a cylinder chamber  63 , the lower open part of which is closed, in the lower bearing  33  forming the low stage-side rotary type compression mechanism  3  by a thrust plate  61  and a cover plate  62 . In the cylinder chamber  63 , a rotor  64  fitted to an eccentric shaft  68  formed at the lower end of the crankshaft  24  and revolved while being in contact with the inner peripheral surface of the cylinder chamber  63  is disposed. The rotor  64  is integrally provided with a blade  64 A for partitioning the interior of the cylinder chamber  63  into an oil supply chamber  63 A and an oil exhaust chamber  63 B. By this positive displacement lubrication pump  60 , the lubricating oil  27  stored in the lower part of the hermetic housing  2  is sucked into the oil supply chamber  63 A through a suction opening  65 , and discharged from the oil exhaust chamber  63 B to a discharge opening  66  and fed to the oil feeding hole  11  through a communication path  67 . 
   The operation of the compressor  1  constructed as described above is explained. 
   In the low stage-side rotary type compression mechanism  3 , a refrigerant gas having a low pressure is sucked into the cylinder chamber  31  from the accumulator, not shown, via the suction pipe  37 . This refrigerant gas is compressed to the intermediate pressure by the rotation of the rotor  34  made via the electric motor  21  and the crankshaft  25 , and then is discharged into the discharge cavity  35 . The refrigerant gas is further discharged from the discharge cavity  35  into the hermetic housing  2  through the discharge opening provided in the discharge cover  36 . Thereby, the interior of the hermetic housing  2  is made to have an intermediate-pressure atmosphere, and therefore the electric motor  21  and the lubricating oil  27  are made to have a temperature equivalent to that of the intermediate-pressure refrigerant gas. 
   The above-mentioned intermediate-pressure refrigerant gas is sucked into the compression chambers  45  of the high stage-side scroll type compression mechanism  4  through the suction opening  52  that is open to the hermetic housing  2 . In the high stage-side scroll type compression mechanism  4 , the electric motor  21  is driven, and thereby the orbiting scroll  44  is revolved with respect to the fixed scroll  43  via the crankshaft  26 , the crank part  26 A, and the drive bush  46 , by which the refrigerant gas is compressed. Thereby, the intermediate-pressure refrigerant gas is compressed to a high-pressure state, and is discharged into the discharge chamber  49  through the discharge valve  48 . 
   The high temperature and pressure refrigerant gas discharged into the discharge chamber  49  is discharged from the compressor  1  through the discharge pipe  51  connected to the discharge chamber  49 . 
   While the above-described operation is performed, the lubricating oil  27  stored in the bottom part of the hermetic housing  2  is fed to the predetermined lubrication locations of the low stage-side rotary type compression mechanism  3  and the high stage-side scroll type compression mechanism  4  via the oil feeding hole  11  by the positive displacement lubrication pump  60 , so that the low stage-side rotary type compression mechanism  3  and the high stage-side scroll type compression mechanism  4  can be lubricated surely. Specifically, the lubricating oil  27  in the hermetic housing  2  is sucked into the oil supply chamber  63 A through the suction opening  65 , being discharged from the oil exhaust chamber  63 B to the discharge opening  66  by the revolution of the rotor  64 , and is sent out to the oil feeding hole  11  via the communication path  67 . By this lubricating operation of the positive displacement lubrication pump  60 , even the high stage-side scroll type compression mechanism  4 , for which differential pressure lubrication is difficult to do, can be lubricated surely. 
   As described above, in the compressor  1 , the positions of the oil exhaust hole  42 H formed in the high stage-side scroll type compression mechanism  4 , the cut part  22 C, and the blade  38  in the low stage-side rotary type compression mechanism  3  coincide with each other in the vertical direction. Therefore, the lubricating oil  27  supplied to the high stage-side scroll type compression mechanism  4  is collected in the concave part of the bearing  40 , and then is exhausted through the oil exhaust hole  42 H. Thereafter, the lubricating oil passes through the cut part  22 C while dropping freely, and is fed toward the blade  38  in the low stage-side rotary type compression mechanism  3 . Therefore, by controlling the rotational speed of the compressor  1  by an inverter and by using CO 2  as the refrigerant gas, the lubrication between the blade  38  and the cylinder body  31  is secured even if the oil level of the lubricating oil  27  is lower than the position of the cylinder body  31  of the low stage-side rotary type compression mechanism  3 . For this reason, the mechanical efficiency is not decreased by the friction between the blade  38  and the cylinder body  31  (groove), and also the reliability of the compressor  1  is not decreased by the friction. Further, since the refrigerant gas is prevented from flowing in between the suction chambers or the compression chambers from the back surface of the blade  38 , the compression efficiency can be prevented from decreasing. 
   The compressor  1  is configured so that the arrangement portions of the oil exhaust hole  42 H, the cut part  22 C, and the blade  38  in the low stage-side rotary type compression mechanism  3  coincide with each other in the vertical direction. Therefore, the oil feeding path of the lubricating oil  27  from the oil exhaust hole  42 H to the blade  38  in the low stage-side rotary type compression mechanism  3  is the shortest. Thereby, the time of contact with the refrigerant gas can be shortened, which is effective in restraining the dissolution of the lubricating oil  27  in the refrigerant gas. Also, for the compressor  1 , a guide for guiding the lubricating oil  27  supplied to the high stage-side scroll type compression mechanism  4  to the arrangement portion of the blade  38  need not be provided separately, so that the construction of the compressor  1  need not be complicated. 
   However, the present invention embraces a mode in which the lubricating oil  27  supplied to the high stage-side scroll type compression mechanism  4  is fed toward the blade  38  by providing the guide even if the positions of the oil exhaust hole  42 H, the cut part  22 C, and the blade  38  in the low stage-side rotary type compression mechanism  3  do not coincide with each other in the vertical direction. 
   The phrase of “toward the blade  38 ” includes a case where the lubricating oil  27  reaches the blade  38  as the result of being fed to the vicinity of the blade  38  besides being fed directly to the blade  38 . For example, in the case where the lubricating oil  27  is fed to the broached hole  39 H, the lubricating oil  27  is sucked from the cylinder chamber  31  side on which the lubricating oil  27  is at a low pressure, and resultantly the lubricating oil  27  reaches the blade  38 . In this case, even if the feed amount of the lubricating oil  27  is too large, the excess lubricating oil  27  returns to the bottom part of the hermetic housing  2  passing through the broached hole  39 H. Therefore, an increase in oil circulation rate (the quantity of oil circulating together with the refrigerant gas, OCR) caused by the raised excess lubricating oil  27  can be prevented. 
   Second Embodiment 
   Next, a second embodiment of the present invention is explained with reference to  FIG. 4 . 
   In the second embodiment, a tube body  69  is provided in the path for feeding the lubricating oil  27 , which is exhausted from the oil exhaust hole  40 H and the oil exhaust hole  42 H, toward the blade  38 . Since the lubricating oil  27  exhausted from the oil exhaust hole  40 H and the oil exhaust hole  42 H passes through the interior of the tube body  69 , the contact of the lubricating oil  27  with the refrigerant gas in the hermetic housing  2  is reduced. If CO 2  is used as the refrigerant gas as described above, the dissolution amount of the lubricating oil  27  in the refrigerant gas (CO 2 ) increases, so that the OCR increases. Therefore, the compressor in accordance with the second embodiment, in which the tube body  69  is provided, is effective in reducing the OCR in the case where CO 2  is used as the refrigerant gas. 
   Although the tube body  69  is used in this embodiment, any member such as a trough-shaped member or a plate-shaped member may be used if the member has a function for restraining the contact of the lubricating oil  27  with the refrigerant gas. 
   Third Embodiment 
   As the compressor  1  shown in  FIG. 1 , an example in which the rotary type compression mechanism has a single cylinder (single rotary) has been shown. However, the present invention can be applied to a compressor  200 , in which the rotary type compression mechanism is configured so as to have two cylinders (twin rotary) as shown in  FIG. 5  and other portions are configured in the same manner as those of the compressor  1  shown in  FIG. 1 . The twin rotary is provided with two cylinder bodies  30   a  and  30   b , and the cylinder body  30   a  has a cylinder chamber  31   a  and the cylinder body  30   b  has a cylinder chamber  31   b . In the cylinder chamber  31   a , a rotor  34   a  is disposed, and in the cylinder chamber  31   b , a rotor  34   b  is disposed. The refrigerant gas sucked into the cylinder chambers  31   a  and  31   b  via suction pipes  37   a  and  37   b  connected to the accumulator, respectively, is compressed by the rotations of the rotors  34   a  and  34   b . A mechanism in which the cylinder body  30   a  is an element is referred to as a first rotary, and a mechanism in which the cylinder body  30   b  is an element is referred to as a second rotary. The same symbols as those in  FIG. 1  denote the same elements as those of the compressor  1  shown in  FIG. 1 . In this embodiment, as shown in  FIG. 6 , a blade  38   a  of the first rotary and a blade  38   b  of the second rotary are sometimes arranged with the crankshaft  25  being held therebetween. 
   In the case of the compressor  200  provided with the above-mentioned twin rotary, the lubricating oil  27  exhausted from the oil exhaust hole  42 H is fed to the first rotary positioned on the upper stage side. 
   For the second rotary positioned on the lower stage side, it is relatively easy to control the oil level thereof so that the second rotary is immersed in the lubricating oil  27 . Even in the case where the rotational speed of the compressor  200  is controlled by the inverter, and CO 2  is used as the refrigerant gas, the blade  38   b  of the second rotary can be lubricated properly. Contrarily, for the first rotary arranged on the upper stage side, there is a fear that the blade  38   a  cannot be lubricated due to the changes in oil level of the lubricating oil  27 . Therefore, the lubricating oil  27  exhausted from the oil exhaust hole  42 H is fed to the blade  38   a  of the first rotary positioned on the upper stage side. 
   In this case, even if the lubricating oil  27  exhausted from the oil exhaust hole  40 H and the oil exhaust hole  42 H is fed to the blade  38   a  of the first rotary on the upper stage side, it is difficult to feed the lubricating oil  27  to the blade  38   b  of the second rotary on the lower stage side. Therefore, this embodiment in which the lubricating oil  27  exhausted from the oil exhaust hole  40 H and the oil exhaust hole  42 H is fed to the blade  38   a  of the first rotary on the upper stage side is especially effective for the compressor  200  in which the blade  38   a  of the first rotary and the blade  38   b  of the second rotary are arranged with the crankshaft  25  being held therebetween. 
   The above is an explanation of the embodiments of the present invention. The present invention is not limited to the above-described embodiments, and changes can be made appropriately without departing from the spirit and scope of the present invention.