JP4583546B2 - Centrifugal compressor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a barrel-type centrifugal compressor in which an outer casing is provided outside an inner casing.
[0002]
[Prior art]
Conventionally, a technique disclosed in Japanese Patent Application Laid-Open No. 55-7914 is known as a technique in such a field. This publication describes a so-called barrel-type centrifugal compressor in which an outer casing is provided outside a middle case (inner casing). A diaphragm is attached inside the inner casing, and a plurality of impellers fixed to a rotating shaft (main shaft) are accommodated. The outer casing is a combination of a cylindrical body (case) and two side lids. The body portion is provided with a suction nozzle (suction port) and a discharge nozzle (discharge port). The main shaft to which the impeller is fixed is provided on each of the two side covers that form the outer casing.
[0003]
[Problems to be solved by the invention]
In recent years, in order to improve the efficiency of a centrifugal compressor, it may be desired to adjust the amount of fluid sucked from a suction nozzle. In general, the suction flow rate is adjusted by a flow rate adjusting mechanism having the following configuration. That is, the flow rate adjusting mechanism is composed of a suction vane provided in the suction nozzle and a variable angle mechanism for changing the attachment angle of the suction vane, and obtains a driving force from a driving unit provided outside the centrifugal compressor. The angle of the suction vane was controlled by operating the angle changing mechanism to adjust the suction flow rate.
[0004]
However, the angle changing mechanism provided in the centrifugal compressor has a complicated structure using a guide ring, a link, and the like, and in order to provide such a angle changing mechanism, a large space is required in the outer casing. For this reason, there is a problem that the entire apparatus becomes large. It has been difficult to apply such a variable angle mechanism to a barrel-type centrifugal compressor.
[0005]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a barrel-type centrifugal compressor that has a variable angle mechanism that can reliably control a suction vane and that can be reduced in size.
[0006]
[Means for Solving the Problems]
A centrifugal compressor according to the present invention is a barrel-type centrifugal compressor in which a cylindrical outer casing having a suction port and a discharge port is provided outside an inner casing that houses an impeller attached to a main shaft. A plurality of suction vanes each having a mounting shaft extending in parallel to the main shaft and formed in a circle surrounding the main shaft in an inflow path for introducing fluid sucked from the mouth into the impeller; and each suction vane A plurality of first gears fixed to the mounting shaft and teeth for meshing are formed on the outer periphery , arranged on the main shaft side from the first gear, and each first gear by the teeth for meshing And an annular ring gear that can rotate around the main shaft and a first gear and a side that is in mesh with the ring gear of the first gear. Then outer casing A second gear having a drive shaft which penetrates, with provided outside the outer casing, characterized in that it comprises a gear drive unit connected to the drive shaft.
[0007]
In the present invention, the first gear fixed to the plurality of suction vanes is meshed with an annular ring gear provided closer to the main shaft than the first gear, and is connected to a drive unit outside the outer casing. The second gear and any one of the first gears are meshed with each other. As a result, when the second gear is rotated by the drive unit, the first gear meshed with the second gear is rotated, and accordingly, the ring gear meshed with the first gear is rotated around the main shaft. . When the ring gear rotates, only the ring gear meshes with the other first gear that does not mesh with the second gear. Thereby, if the second gear is rotated by the drive unit, each first gear rotates, and the angle of the suction vane fixed to each first gear can be changed. Further, in the centrifugal compressor according to the present invention, the drive shaft is connected to the outer diameter of the ring gear by the configuration in which the first gear is meshed around the ring gear and the second gear meshed on the outer side is driven. Since the first gear is separated from the main shaft by the combined size with the outer diameter of the first gear, it is possible to avoid interference between the drive shaft and a bearing provided near the main shaft. Thereby, it is not necessary to increase the diameter of the ring gear for the purpose of avoiding interference with a bearing or the like, the rotation radius of the ring gear can be reduced, and the outer casing covering the ring gear or the like can be reduced in size.
[0008]
In the centrifugal compressor, the drive shaft includes a gear side shaft having a second gear and a drive unit side shaft connected to the gear drive unit, and the gear side shaft and the drive unit side shaft have torque. It is good also as the characteristics connected by the torque variable means which can change ratio.
[0009]
By adopting such a configuration, the torque transmitted from the drive unit side shaft can be absorbed to some extent by the torque varying means and transmitted to the gear side shaft.
Thereby, since the burden which acts on a gear side shaft can be reduced, a gear side shaft can be reduced in diameter.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a centrifugal compressor according to the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.
[0011]
FIG. 1 is a cross-sectional view of a main part showing a centrifugal compressor 10 of the present embodiment. The centrifugal compressor 10 is configured as a so-called barrel-type single-shaft multistage centrifugal compressor 10 and includes a plurality (in this case, four) impellers (impellers) 14 attached to a main shaft 12.
[0012]
Each impeller 14 is accommodated in an inner casing 16 formed in a horizontal split shape or a ring shape. A diaphragm 18 that defines a flow path connecting the impellers 14 is attached to the inside of the inner casing 16. On the other hand, the outer casing 20 includes a cylindrical body portion 22 and two side lids 24 and 26. The side lid 24 is firmly attached to the body portion 22 by welding and the side lid 26 is bolted or the like. Are combined.
[0013]
The body portion 22 of the outer casing 20 is provided with a suction port 28 and a discharge port 30 that extend in a direction orthogonal to the main shaft 12. Further, the side lids 24 and 26 are provided with a gas seal type shaft seal portion 32 and a pipe (not shown) for supplying a buffer gas. Further, a bearing casing 38 to which a journal bearing 34 that supports the main shaft 12 is attached is fixed to the side lids 24 and 26. In FIG. 1, a thrust bearing 36 is further disposed outside the journal bearing 34 in the bearing casing 38 located on the suction port 28 side (right side in FIG. 1).
[0014]
A plurality of (in this case, twelve) suction vanes 40, which is a feature of the present embodiment, are provided in the inflow passage that connects the suction port 28 and the suction port 15 of the first impeller 14. Each suction vane 40 is located in the rear stage of the guide vane 41 arranged from the most entrance of the inflow passage. As shown in FIG. 2, each suction vane 40 is disposed so as to form a circumference surrounding the main shaft 12. Then, by rotating the suction vane 40 as shown by a one-dot chain line in FIG. 2, the amount of fluid passing between the suction vanes 40 toward the suction port 15 of the first stage impeller 14 is adjusted. Is done.
[0015]
Next, a mechanism for changing the angle of each suction vane 40 will be described. As shown in FIG. 1, each suction vane 40 has a mounting shaft 42 extending in parallel with the main shaft 12. Then, a driven gear (first gear) 44 that is operated by a mechanism described below and rotates the suction vane 40 is fixed to the mounting shaft 42. Each driven gear 44 fixed to the attachment shaft 42 of each suction vane 40 is meshed with an annular ring gear 46 located on the main shaft 12 side from each driven gear 44, and the ring gear 46 is rotated to rotate. The attachment shaft 42 of each suction vane 44 rotates together with each driven gear 44. On the other hand, among the plurality of driven gears 44, one driven gear 44 is meshed with a drive gear (second gear) 48 connected to an external drive device 60.
[0016]
FIG. 3 is an enlarged perspective view of a main part schematically showing each gear (the driven gear 44, the ring gear 46, and the driving gear 48). As shown in FIG. 3, a plurality of driven gears 44 are engaged with the outside of a ring gear 46 having teeth for engagement on the outer periphery. A drive gear 48 is meshed with one driven gear 44 from the side opposite to the side where the ring gear 46 is located. In addition, the area | region R (refer FIG. 1) with which each gear is mesh | engaged is satisfy | filled with grease, and, thereby, each gear can rotate smoothly.
[0017]
As shown in FIG. 1, the drive gear 48 is disposed below the main shaft 12 and is connected to a drive device 60 provided outside the outer casing 20 by a drive shaft 52 that passes through the outer casing 20 (side cover 26). Yes. The drive shaft 52 is composed of two members: a shaft 53 on the drive gear 48 side to which the drive gear 48 is connected and a shaft 54 on the drive device 60 side to which the drive device 60 is connected. The shaft 53 on the drive gear 48 side is supported by a ball bearing 50 attached to the side lid 26. The two shafts 53 and 54 are connected by a torque limiter 56 that can change the torque ratio.
[0018]
Next, operation | movement of the centrifugal compressor 10 of this embodiment is demonstrated. First, the main shaft 12 is rotated, each impeller 14 is rotated, and fluid is sucked from the suction port 28. At this time, the angle of the suction vane 40 is changed to adjust the flow rate of flow into the first stage impeller 14 communicating with the suction port 28. That is, the drive gear 52 is rotated by rotating the drive shaft 52 by the drive device 60. At this time, the torque applied from the drive device 60 is reduced to some extent by a torque limiter 56 provided in the middle of the drive shaft 52 and transmitted to the shaft 53 on the drive gear 48 side. For this reason, the burden concerning the shaft 53 by the side of the drive gear 48 can be reduced.
[0019]
When the drive gear 48 rotates, one driven gear 44 meshed with the drive gear 48 rotates, and at the same time, the ring gear 46 meshed with the driven gear 44 rotates around the main shaft 12. Then, as the ring gear 46 rotates, each driven gear 44 meshed with the ring gear 46 also rotates, so that each suction vane 40 connected to each driven gear 44 via the mounting shaft 42. Rotates and its angle changes.
[0020]
The fluid that has passed through the suction vane 40 and has flowed into the suction port 15 of the impeller 14 passes through the four impellers 14 and is compressed and discharged from the discharge port 30 to the outside of the centrifugal compressor 10.
[0021]
Thus, in the centrifugal compressor 10 of the present embodiment, the driven gear 44 fixed to the mounting shaft 42 of the absorption vane 40 is meshed with the ring gear 46 that rotates around the main shaft 12. Thereby, the suction vane 40 can be rotated by rotating the ring gear 46, and the angle can be changed.
[0022]
The rotational driving force for rotating the ring gear 46 is transmitted by a driving gear 48 meshed with one driven gear 44 from the side opposite to the side where the main shaft 12 is located. Since the drive gear 48 is disposed at a position separated from the main shaft 12, interference between the bearings 32, 34, 36 and the like disposed in the vicinity of the main shaft 12 and the drive shaft 52 of the drive gear 48 occurs. It has no configuration. Accordingly, it is not necessary to increase the diameter of the ring gear 46 for the purpose of avoiding interference with the bearings 32, 34, 36, etc., and the angle changing mechanism of the suction vane 40 can be configured by the ring gear 46 having a small diameter. Miniaturization can be achieved.
[0023]
The drive shaft 52 for connecting the drive gear 48 and the drive device 60 is composed of two members, a shaft 53 on the drive gear 48 side and a shaft 54 on the drive device 60 side. They are connected by a torque limiter 56. As a result, the torque transmitted from the drive device 60 can be reduced by the torque limiter 56 and transmitted to the shaft 53 on the drive gear 48 side, so that the diameter of the shaft 53 on the drive gear 48 side can be reduced, and the size of the device can be reduced. Can be achieved.
[0024]
Next, a second embodiment of the present invention will be described. The centrifugal compressor 70 of the second embodiment shown in FIG. 4 has the same basic configuration as the centrifugal compressor 10 of the first embodiment, but the shape of the drive gear 72 is different.
[0025]
As shown in FIG. 5, the drive gear 72 of the second embodiment is not circular, but has a shape in which a part of the side that does not mesh with the driven gear 44 is cut off. As apparent from FIG. 2, the suction vane 40 does not necessarily rotate once, and the suction flow rate from the suction port 28 can be adjusted by changing the angle within a range of about 0 to 90 °. it can. Therefore, the drive gear 72 is not necessarily rotated once, and the driven gear 44 may be rotated within the above-described range. The range necessary for meshing between the driven gear 44 and the drive gear 72 is determined by the ratio of the diameters of the driven gear 44 and the drive gear 72.
[0026]
With such a configuration, the space occupied by the drive gear 72 in the outer casing 20 can be reduced, and the centrifugal compressor 70 can be reduced in size. Further, as shown in FIG. 4, an O-ring 74 can be provided in the reduced space to improve the sealing performance.
[0027]
As mentioned above, although each embodiment of the centrifugal compressor of this invention has been described in detail, this invention is not limited to each said embodiment.
[0028]
In each of the above embodiments, the circular driven gear 44 is adopted and teeth are provided on the entire circumference. However, the driven gear 44 rotates and the ring gear 46 according to the rotation angle of the suction vane 40. It is good also as providing a tooth | gear only in the part which meshes with. Thereby, saving of material cost and size reduction of an apparatus can be achieved.
[0029]
Further, a bearing that supports the drive shaft 52 protruding from the outer casing 20 may be provided. Thereby, the drive shaft 52 can be extended to a position separated from the centrifugal compressor 10.
[0030]
【The invention's effect】
According to the present invention, in the suction vane of the centrifugal compressor, the first gear fixed to the suction vane mounting shaft is meshed with the ring gear rotatable around the main shaft. Accordingly, when the ring gear is rotated, the first gear is also rotated, and the angle of the suction vane to which the first gear is fixed can be changed.
[0031]
The first gear is meshed with a second gear connected by a drive shaft and a drive shaft outside the outer casing from the side opposite to the side meshed with the ring gear. As a result, the drive shaft is separated from the main shaft by a dimension that combines the outer diameter of the ring gear and the outer diameter of the first gear without enlarging the diameter of the ring gear and separating the first gear from the main shaft. Thus, it is possible to avoid interference between the drive shaft and the bearing that supports the main shaft. Therefore, a variable angle mechanism having a small diameter of the ring gear can be configured, and the apparatus can be miniaturized.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a centrifugal compressor.
FIG. 2 is a cross-sectional view showing an arrangement direction of suction vanes.
FIG. 3 is a perspective view showing meshing of a ring gear, a driven gear, and a drive gear.
FIG. 4 is a cross-sectional view showing a centrifugal compressor.
FIG. 5 is an explanatory diagram illustrating a drive gear.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Centrifugal compressor, 12 ... Main shaft, 14 ... Impeller, 16 ... Inner casing, 18 ... Diaphragm, 20 ... Outer casing, 22 ... Body, 24, 26 ... Side cover, 28 ... Suction port, 30 ... Discharge port, 32 ... Shaft seal, 34 ... Journal bearing, 36 ... Thrust bearing, 38 ... Bearing casing, 40 ... Suction vane, 41 ... Guide vane, 42 ... Mounting shaft, 44 ... Drive gear, 46 ... Ring gear, 48 ... Drive gear, 50 ... Ball bearing, 52 ..Drive shaft, 53, 54 ... shaft, 56 ... torque limiter, 60 ... drive unit, 70 ... centrifugal compressor, 72 ... drive gear, 74 ... O-ring.

Claims (2)

In the barrel-type centrifugal compressor provided with a cylindrical outer casing having a suction port and a discharge port on the outside of the inner casing that houses the impeller attached to the main shaft,
A plurality of suction vanes having an attachment shaft extending in parallel to the main shaft and provided to form a circumference surrounding the main shaft in an inflow path for introducing fluid sucked from the suction port into the impeller When,
A plurality of first gears fixed to the mounting shaft of each suction vane;
Teeth for meshing are formed on the outer periphery, arranged on the main shaft side from the first gear, meshed with the first gears by the meshing teeth, and rotatable around the main shaft. An annular ring gear,
A second gear having a drive shaft that meshes with the first gear from the opposite side of the first gear that meshes with the ring gear and that extends parallel to the main shaft and penetrates the outer casing. With the gear
A gear drive unit provided outside the outer casing and connected to the drive shaft;
A centrifugal compressor characterized by comprising:   The drive shaft includes a gear side shaft having the second gear and a drive portion side shaft connected to the gear drive portion, and the gear side shaft and the drive portion side shaft change a torque ratio. The centrifugal compressor according to claim 1, wherein the centrifugal compressor is connected by a torque variable means that can be operated.

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