Abstract:
A rotary machine characterized by being equipped with: a rotary drive part; a drive shaft that is rotated about a horizontally extending axis by the rotary drive part; a large gear that is fixed to the drive shaft; a bearing part that rotatably supports the drive shaft, and to which a lubrication oil is supplied; multiple pinions that are driven by being engaged with the large gear; multiple compression parts that are arranged so as to correspond to the multiple pinions and are respectively rotated by the pinions; and a plate that is installed between the bearing part and the large gear and covers at least a portion of the bottom half of the large gear so as to separate the large gear and the bearing part from each other.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a rotary machine, and more particularly to a rotary machine having a gear wheel, and a plurality of pinion gears which mesh with the gear wheel to be driven. 
       BACKGROUND ART 
       [0002]    A centrifugal compressor which is a rotary machine allows gas to pass through a rotating impeller in a radial direction and compresses the gas using a centrifugal force generated at this time. The centrifugal compressor is used, for example, in a petrochemical plant, a natural gas plant, or an air separation plant. 
         [0003]    As the centrifugal compressor, a single-shaft, multi-stage type centrifugal compressor having a structure in which an impeller which compresses gas is attached to a single shaft, and an accelerator-embedded centrifugal compressor (hereinafter, referred to as a geared compressor) having a structure in which impellers are attached to the shaft ends of a plurality of driven shafts, are known. A type of geared compressor which compresses gas using a plurality of compressing parts having impellers provided at the shaft ends of a plurality of driven shafts is known. 
         [0004]    In PTL 1, a geared compressor in which a pinion gear is disposed on the upper side of a gear wheel attached to a driving shaft is described. In order to prevent drain oil discharged from the bearing of the pinion gear from falling on the gear wheel, the geared compressor includes covers provided on both sides of the bearing corresponding to the pinion gear disposed on the upper side. 
       CITATION LIST 
     Patent Literature 
       [0005]    [PTL 1] Japanese Patent No. 3735147 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0006]    However, in the rotary machine such as the geared compressor, various loss reductions are attempted. 
         [0007]    In a process of examination regarding loss reductions, the inventors found that in a rotary machine having a gear train constituted by a gear wheel and a pinion gear, the adhesion of drain oil discharged from a bearing of a driving shaft to the gear wheel is a factor that causes unexpected loss. 
         [0008]    That is, it was found that power loss occurs when the gear wheel is rotated, since the drain oil discharged from the bearing of the driving shaft to which the gear wheel is attached adheres to a side surface of the gear wheel that is rotated. Particularly, in a case of a rotary machine having high power, this loss is noticeable. However, it has been observed that it is difficult to quantitatively estimate the loss, and there is a possibility that higher loss than postulated may be generated. 
         [0009]    In the case of the geared compressor described in PTL 1, although the adhesion of the drain oil to the upper half portion of the gear wheel is prevented, the adhesion thereof to the lower half portion of the gear wheel is not prevented, and the drain oil that adheres to the lower half portion of the gear wheel becomes the cause of power loss. 
         [0010]    The present invention provides a rotary machine capable of reducing required power by reducing power loss when a gear wheel is rotated. 
       Solution to Problem 
       [0011]    A rotary machine of the present invention includes: a rotational driving part; a driving shaft which is rotated by the rotational driving part about an axis that extends in a horizontal direction; a gear wheel which is fixed to the driving shaft; a bearing section which rotatably supports the driving shaft and is supplied with lubricating oil; a plurality of pinions which mesh with the gear wheel to be driven; a plurality of compressing parts which are provided to correspond to the plurality of pinions and are respectively rotated by the pinions; and a first plate which is disposed between the bearing section and the gear wheel, and covers a region of at least a portion of a lower half of the gear wheel so as to separate the gear wheel from the bearing section. 
         [0012]    In this configuration, drain oil discharged from the bearing section is prevented from falling and adhering onto the lower half portion of the gear wheel by the first plate. Accordingly, power loss that occurs due to the adhesion of the drain oil to the gear wheel when the gear wheel is rotated can be reduced. 
         [0013]    In the rotary machine, it is preferable that a lower end of the first plate extends further downward than a lower end of the gear wheel. 
         [0014]    In this configuration, the adhesion of the drain oil to the gear wheel can be further prevented. 
         [0015]    The rotary machine may be configured to further include a second plate which is disposed between an upper half portion of the bearing section and the gear wheel to separate the gear wheel from the bearing section. 
         [0016]    In this configuration, the drain oil discharged toward the upper side from the bearing section can be prevented from adhering to the gear wheel by the second plate. 
         [0017]    The rotary machine may be configured to further include: a driven shaft bearing section which rotatably supports a driven shaft to which the pinion is fixed; and a third plate which is disposed between a lower half portion of the driven shaft bearing section and the gear wheel to separate the gear wheel from the driven shaft bearing section. 
         [0018]    In this configuration, the drain oil discharged from the driven shaft bearing section can be prevented from adhering to the gear wheel by the third plate. 
         [0019]    The rotary machine may be configured to further include a casing which supports the bearing section, and the casing may be provided with an oil groove which guides drain oil, which is discharged from the bearing section toward the other side of the bearing section in an axial direction, to one side of the bearing section in the axial direction, on which the first plate is disposed. 
       Advantageous Effects of Invention 
       [0020]    According to the present invention, the drain oil discharged from the bearing section is prevented from falling and adhering onto the lower half portion of the gear wheel by the plate. Accordingly, power loss that occurs due to the adhesion of the drain oil to the gear wheel when the gear wheel is rotated can be reduced. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0021]      FIG. 1  is a plan view of a geared compressor of an embodiment of the present invention. 
           [0022]      FIG. 2  is a sectional view taken along A-A of  FIG. 1 , and is a view illustrating the arrangement of baffle plates of the geared compressor. 
           [0023]      FIG. 3  is a sectional view taken along B-B of  FIG. 2 , and is a view illustrating the arrangement of first baffle plates and second baffle plates. 
           [0024]      FIG. 4  is a sectional view taken along C-C of  FIG. 2 , and is a view illustrating the arrangement of third baffle plates. 
           [0025]      FIG. 5  is a front view of an oil thrower of the embodiment of the present invention, viewed in an axial direction. 
           [0026]      FIG. 6  is a sectional view of the oil throwers of the embodiment of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0027]    Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. 
         [0028]    A geared compressor which is a rotary machine of the embodiment of the present invention includes a gear train therein, and has a multi-shaft, multi-stage configuration that drives a plurality of impellers. 
         [0029]    As illustrated in  FIG. 1 , a geared compressor  1  includes a rotational driving part  2  which generates power, a driving shaft  3  which is a rotary shaft that is rotated by the rotational driving part  2  about an axis that extends in a horizontal direction, a gear wheel  4  fixed to the driving shaft  3 , two pinion gears  6  which mesh with the gear wheel  4  to be driven, two driven shafts  5  which respectively act as the shafts of the pinion gears  6 , and three compressing parts  11 ,  12 , and  13  which are driven by power transmitted to the driven shafts  5 . 
         [0030]    As the rotational driving part  2 , for example, an electric motor may be employed. The gear wheel  4  and the pinion gears  6  constitute a gear train that functions as an accelerator which increases the speed of the driving shaft  3 . 
         [0031]    The two pinion gears  6  are rotated by the rotation of the gear wheel  4 . The two pinion gears  6  are constituted by a lower-pressure-stage pinion gear  6   a , and a higher-pressure-stage pinion gear  6   b  which is smaller than the lower-pressure-stage pinion gear  6   a . Therefore, the higher-pressure-stage pinion gear  6   b  is rotated at a higher rotation speed than that of the lower-pressure-stage pinion gear  6   a.    
         [0032]    The two driven shafts  5  are constituted by a lower-pressure-stage driven shaft  5   a  which extends toward both ends of the lower-pressure-stage pinion gear  6   a  in the central axis direction, and a higher-pressure-stage driven shaft  5   b  which extends toward both ends of the higher-pressure-stage pinion gear  6   b  in the central axis direction. 
         [0033]    The three compressing parts  11 ,  12 , and  13  are provided to correspond to the pinion gears  6 , and are constituted by the first-stage compressing part  11  which is provided at the front end of the lower-pressure-stage driven shaft  5   a  on the opposite side of a side on which the rotational driving part  2  is provided, the second-stage compressing part  12  which is provided at the rear end of the higher-pressure-stage driven shaft  5   b , and the first-stage compressing part  11  which is provided at the front end of the higher-pressure-stage driven shaft  5   b . A counterweight  7  is attached to the other end of the lower-pressure-stage driven shaft  5   a.    
         [0034]    In the following description, the axial directions of the driving shaft  3  and the driven shafts  5  are simply referred to as an axial direction, and a side (upper side in  FIG. 1 ) on which the rotational driving part  2  is provided in the axial direction is referred to as a rear side, while the opposite side (lower side in  FIG. 1 ) of the side on which the rotational driving part  2  is provided in the axial direction is referred to as a front side. 
         [0035]    Each of the first-stage compressing part  11 , the second-stage compressing part  12 , and the third-stage compressing part  13  includes an impeller  14 , and a scroll casing (not illustrated) which covers the impeller  14  and has a gas introduction portion and a gas discharge port. 
         [0036]    Each of the first-stage compressing part  11 , the second-stage compressing part  12 , and the third-stage compressing part  13  compresses an operating fluid by using the impeller  14 . The impeller  14  discharges the operating fluid suctioned from the gas introduction portion toward the radially outer peripheral side via a passage formed therein. The first-stage compressing part  11 , the second-stage compressing part  12 , and the third-stage compressing part  13  are connected via pipes  8 . 
         [0037]    The gear train constituted by the gear wheel  4  and the plurality of pinion gears  6  is accommodated inside a gear casing  9 , and the driving shaft  3 , the lower-pressure-stage driven shaft  5   a , and the higher-pressure-stage driven shaft  5   b  are rotatably supported by bearings  15  and  16  in the gear casing  9 . The bearings  15  and  16  are constituted by the driving shaft bearings  15  which are disposed on the front side and the rear side of the gear wheel  4  in the axial direction, and the driven shaft bearings  16  which are disposed on the front side and the rear side of the pinion gears  6  in the axial direction. 
         [0038]    The bearings  15  and  16  are journal bearings (radial bearings) having a plurality of bearing pads  17  (see  FIGS. 3 and 4 ) for supporting the driving shaft  3  and the driven shafts  5 . The bearings  15  and  16  include oil supply nozzles (not illustrated) which supply lubricating oil between the shafts and the bearing pads  17 . Drain oil which finishes the function as the lubricating oil is discharged toward both sides of the bearing pads  17  in the axial direction. 
         [0039]    As illustrated in  FIG. 2 , the gear casing  9  includes a lower casing  19  of which the upper side is open, and an upper casing  20  which covers the upper side of the lower casing  19 . A flanged portion  21  having a shape that extends from the opening in the horizontal direction is formed in the lower casing  19 . 
         [0040]    The gear casing  9  includes a plurality of bearing fixing parts  23  and  24 . The bearing fixing parts  23  and  24  are constituted by the first bearing fixing parts  23  which fix the driving shaft bearings  15 , and the second bearing fixing parts  24  which fix the driven shaft bearings  16 . 
         [0041]    The bearing fixing parts  23  and  24  are constituted by bearing fixing part lower half portions  23   a  and  24   a  which are formed integrally with the flanged portion  21  of the lower casing  19 , and bearing fixing part upper half portions  23   b  and  24   b  which are attached to the upper portions of the bearing fixing part lower half portions  23   a  and  24   a  using fastening members such as bolts. The bearing fixing part upper half portions  23   b  and  24   b  may also be configured to be integrated with the upper casing  20 . 
         [0042]    The bearings  15  and  16  are interposed between the bearing fixing part upper half portions  23   b  and  24   b  and the bearing fixing part lower half portions  23   a  and  24   a  so as to be fixed to the flanged portion  21  of the gear casing  9 . The bearing fixing part lower half portions  23   a  and  24   a  of the lower casing  19  are provided with oil grooves  27  which act as outflow passages of the drain oil from the bearings  15  and  16 . 
         [0043]    Here, the structure of the oil grooves  27  will be described with reference to  FIG. 3 . The oil grooves  27  are formed to guide the drain oil discharged to the opposite side of the gear wheel  4  (the other side in the axial direction) to the gear wheel  4  side (one side in the axial direction). Specifically, the oil grooves  27  are formed so that an upper surface which is the upper surface of the bearing fixing part lower half portion  23   a  on the opposite side of the gear wheel  4  is communicated with a side surface which is the side surface of the bearing fixing part lower half portion  23   a  on the gear wheel  4  side. 
         [0044]    The geared compressor  1  of this embodiment is provided with a plurality of baffle plates  28 ,  30 , and  31  for preventing the drain oil discharged from the bearings  15  and  16  from adhering to the gear wheel  4 . The baffle plates  28 ,  30 , and  31  are formed by performing sheet-metal working on a steel sheet such as SUS304. 
         [0045]    Among the plurality of baffle plates, the first baffle plates  28  are disposed on both sides of the gear wheel  4  in the axial direction between the driving shaft bearings  15  and the gear wheel  4  so as to separate the driving shaft bearings  15  from the gear wheel  4 . 
         [0046]    The first baffle plate  28  is a rectangular plate member which covers the region of at least a portion of the lower half of the gear wheel  4  and has dimensions such that the width dimension W (see  FIG. 2 ) thereof in the horizontal direction perpendicular to the axial direction is sufficiently greater than the diameter of the driving shaft bearing  15  and the first baffle plate  28  sufficiently covers the outlet portion of the oil groove  27  when viewed in the axial direction. The upper end of the first baffle plate  28  is at the same position as the center of the driving shaft  3 , and the lower end thereof is positioned at a slightly lower position than the lower end of the gear wheel  4 . 
         [0047]    As illustrated in  FIG. 3 , the first baffle plates  28  are fixed to the inner surface of the lower casing  19  via bent portions  29  provided on both sides thereof so as to be separated from the inner surface of the lower casing  19  by a predetermined dimension G 1 . In addition, the upper portions of the first baffle plates  28  are provided with semicircular cut-outs in order to prevent interference with the driving shaft  3  and the driving shaft bearings  15 . 
         [0048]    The second baffle plates  30  are disposed between the upper half portions of the driving shaft bearings  15  and the gear wheel  4  to separate the driving shaft bearings  15  from the gear wheel  4 . The second baffle plates  30  are attached to the bearing fixing part upper half portions  23   b  for fixing the driving shaft bearings  15 . 
         [0049]    In the second baffle plates  30 , the second baffle plate on the front side of the gear wheel  4  in the axial direction and the second baffle plate on the rear side of the gear wheel  4  in the axial direction have different shapes. The second baffle plate  30  on the front side in the axial direction is bent toward the upper side from the bearing fixing part upper half portion  23   b  so as to avoid a boss portion  4   a  of the gear wheel  4 . The second baffle plate  30  on the rear side in the axial direction is bent toward the lower side from the upper end of the bearing fixing part upper half portion  23   b.    
         [0050]    The third baffle plates  31  are disposed between the lower half portions of the driven shaft bearings  16  and the gear wheel  4  so as to separate the driven shaft bearings  16  from the gear wheel  4 . As illustrated in  FIG. 4 , the third baffle plates  31  are attached to the bearing fixing part lower half portions  24   a  for fixing the driven shaft bearings  16 . The principal surfaces of the third baffle plates  31  are fixed to the bearing fixing part lower half portions  24   a  for fixing the driven shaft bearings  16  so as to be separated from the inner surface of the lower casing  19  by a predetermined dimension G 2 . 
         [0051]    As illustrated in  FIGS. 5 and 6 , oil throwers  33  for preventing the drain oil discharged from the bearings of the driven shafts  5  from scattering are attached to the driven shaft bearings  16 . The oil throwers  33  are constituted by cut-out rings  34  having discharge ports formed by cutting the lower portions thereof, and covers  35  having a disk shape, and are attached to both sides of the driven shaft bearings  16  in the axial direction by fastening means such as bolts. 
         [0052]    Next, the action of the geared compressor  1  of this embodiment will be described. 
         [0053]    The operating fluid to be compressed is introduced into the first-stage compressing part  11 , the second-stage compressing part  12 , and the third-stage compressing part  13  in this order and is compressed. After the operating fluid is compressed by the third-stage compressing part  13 , the operating fluid is supplied to a predetermined plant P which is a demander of the compressed operating fluid. 
         [0054]    As illustrated in  FIG. 3 , the drain oil which is discharged from the driving shaft bearings  15  and is discharged toward the gear wheel  4  side abuts the first baffle plates  28  and thereafter flows toward the lower side via a section surrounded by the gear casing  9  and the first baffle plates  28 . The drain oil which is discharged from the driving shaft bearings  15  and is discharged toward the opposite side of the gear wheel  4  flows toward the first baffle plates  28  via the oil grooves  27  and flows toward the lower side via a section surrounded by the first baffle plates  28 . 
         [0055]    The drain oil which is discharged from the driving shaft bearings  15  and is discharged while scattering upward, abuts the second baffle plates  30  and is not allowed to be scattered upward by the second baffle plates  30 . 
         [0056]    As illustrated in  FIGS. 5 and 6 , the drain oil which is discharged from the driven shaft bearings  16  is discharged toward the space surrounded by the cut-out rings  34  and the covers  35  of the oil throwers  33  and is discharged toward the lower side from the discharge ports in the lower portions of the cut-out rings  34 . As illustrated in  FIG. 4 , the drain oil which is discharged via the oil grooves  27  and is discharged toward the gear wheel  4  side abuts the third baffle plates  31  and then flows downward. 
         [0057]    According to this embodiment, the drain oil discharged from the driving shaft bearings  15  is prevented from falling and adhering onto the lower half portion of the gear wheel  4  by the first baffle plates  28 . Accordingly, power loss that occurs due to the adhesion of the drain oil to the gear wheel  4  when the gear wheel  4  is rotated can be reduced, and thus the geared compressor  1  that needs low power for the rotational driving part  2  can be provided. 
         [0058]    In addition, since the lower ends of the first baffle plates  28  extend further downward than the lower end of the gear wheel  4 , the adhesion of the drain oil to the gear wheel  4  can be further prevented. 
         [0059]    In addition, since the second baffle plates  30  are disposed between the upper half portions of the driving shaft bearings  15  and the gear wheel  4 , the drain oil discharged toward the upper side from the driving shaft bearings  15  can be prevented from adhering to the gear wheel  4 . 
         [0060]    In addition, since the third baffle plates  31  are disposed between the lower half portions of the driven shaft bearings  16  and the gear wheel  4 , the drain oil discharged from the driven shaft bearings  16  can be prevented from adhering to the gear wheel  4 . 
         [0061]    While the embodiment of the present invention has been described in detail with reference to the drawings, the configurations and combinations thereof in the embodiment are only examples, and additions, omissions, substitutions, and other changes in the configurations may be made without departing from the spirit of the invention. In addition, the present invention is not limited by the embodiment, and is limited only by the appended claims. 
         [0062]    In addition, in the above-described embodiment, an example in which the baffle plates are applied to the geared compressor is used. However, the baffle plates can be applied to any rotary machine that includes a gear train constituted by a gear wheel and a pinion gear, and for example, can be applied to a turbine. 
         [0063]    In addition, the geared compressor of the above-described embodiment has a configuration with three compressing parts. However, the embodiment is not limited thereto, and compressing parts may also be provided at both ends of two driven shafts. 
         [0064]    In addition, the number of the pinion gears is not limited to two, and for example, a third pinion gear may also be disposed on the upper side of the gear wheel. 
       INDUSTRIAL APPLICABILITY 
       [0065]    The present invention can be applied to a rotary machine such as a geared compressor or a turbine, which includes a gear train constituted by a gear wheel and a pinion gear. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           1  geared compressor 
           2  rotational driving part 
           3  driving shaft 
           4  gear wheel 
           5  driven shaft 
           5   a  lower-pressure-stage driven shaft 
           5   b  higher-pressure-stage driven shaft 
           6  pinion gear (pinion) 
           6   a  lower-pressure-stage pinion gear 
           6   b  higher-pressure-stage pinion gear 
           7  counterweight 
           8  pipe 
           9  gear casing 
           11  first-stage compressing part 
           12  second-stage compressing part 
           13  third-stage compressing part 
           14  impeller 
           15  driving shaft bearing 
           16  driven shaft bearing 
           17  bearing pad 
           19  lower casing 
           20  upper casing 
           21  flanged portion 
           23  first bearing fixing part 
           23   a  bearing fixing part lower half portion 
           23   b  bearing fixing part upper half portion 
           24  second bearing fixing part 
           24   a  bearing fixing part lower half portion 
           24   b  bearing fixing part upper half portion 
           27  oil groove 
           28  first baffle plate (first plate) 
           29  bent portion 
           30  second baffle plate (second plate) 
           31  third baffle plate (third plate) 
           33  oil thrower 
           34  cut-out ring 
           35  cover