JP2009174458A - Centrifugal compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a centrifugal compressor improved in durability without increasing its size. <P>SOLUTION: The centrifugal compressor 10 includes a rotary shaft 11, a centrifugal impeller 12 attached to the rotary shaft, a pair of diaphragms 13a, 13b for regulating a flow passage 31 upstream of the centrifugal impeller, and casings 14, 14a for storing the rotary shaft, the centrifugal impeller, and the diaphragms. A plurality of swingable inlet guide vanes 15 are disposed in the annular flow passage and on the same pitch circle. A flow rate control mechanism 30 includes two kinds of long and short shafts 16a, 16b having the inlet guide vanes attached on one end and first gears 17a, 17b attached on the other end, a ring gear 18 engaged with all of the first gears and disposed coaxially with the rotary shaft, and a second gear 19 engaged on an engaging face of the ring gear different from an engaging face engaged with the first gears. The axial position of the first gear is different from that of an adjacent first gear. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a centrifugal compressor, and more particularly to a flow rate adjustment device suitable for being arranged on the suction side of a centrifugal compressor.

  An example of a conventional centrifugal compressor provided with a flow rate adjusting device is described in Patent Document 1. In this publication, in order to improve the durability without increasing the size of the centrifugal compressor, in the barrel type single-shaft multistage centrifuge, the arrangement of gears included in the flow rate adjusting device provided on the suction side is different from that of the conventional one. . That is, the main shaft, the impeller attached to the main shaft, an inflow passage that surrounds the main shaft and guides the gas to be compressed from the radially outer side of the main shaft to the impeller, and the periphery of the main shaft in the inflow passage A plurality of suction vanes (inlet guide vanes) arranged so as to surround each other and swingable about a swing axis parallel to the axis of the main shaft, and a vane drive device for swinging each suction vane are provided. The vane driving device includes a driven gear (first gear) provided in each suction vane, a driving gear (second gear) disposed adjacent to the swing axis direction of the driven gear, and a gear for driving the driving gear. The drive device includes a ring gear in which a first gear portion that meshes with each driven gear and a second gear portion that meshes with the drive gear are arranged adjacent to each other in the swing axis direction.

JP 2006-233901 A

  In the flow rate adjusting device described in Patent Document 1, the inlet guide vane and the first gear are attached to an attachment shaft arranged in parallel to the main shaft. Each first gear meshes with an annular ring gear. A second gear is arranged adjacent to the first gear in the axial direction so as to mesh with the ring gear. Therefore, in the flow control device described in this publication, power is transmitted from the drive unit in the order of the second gear, the ring gear, and the first gear, and the direction of the inlet guide vane attached to the first gear is changed.

  By the way, a reaction force is applied to each inlet guide vane by the working fluid flowing in the flow path. This load is transmitted to the ring gear through the mounting shaft and the first gear. Since the ring gear meshes with all the first gears, a load corresponding to the total number of inlet guide vanes is applied to the ring gear. At the same time, in the ring gear, one second gear meshes with a position where the first gear meshes with a position different in the axial direction. A large tangential load is applied at the position where the ring gear and the second gear mesh. As a result, the second gear configured to have a smaller diameter is required to have higher strength than the first gear and the ring gear.

  In the conventional flow control device described in the above publication, the durability of the flow control device is improved without increasing the size of the centrifugal compressor. However, in order to further reduce the size of the centrifugal compressor, it is necessary to increase the strength or reduce the load of the second gear used in the flow rate adjusting device.

  The present invention has been made in view of the above conventional technology, and further improves the conventional centrifugal compressor to increase the size of the centrifugal compressor while improving the durability of the flow control device of the centrifugal compressor. The purpose is to avoid.

  A feature of the present invention that achieves the above object is that a rotating shaft, at least one centrifugal impeller attached to the rotating shaft, a pair of diaphragms defining a flow path upstream of the centrifugal impeller, and the rotation In a centrifugal compressor that has a shaft, a centrifugal impeller, and a casing that accommodates a diaphragm, and that rotates the rotating shaft with a driving device to compress the sucked gas, the centrifugal compressor is formed upstream of the centrifugal impeller on the suction side. A plurality of inlet guide vanes arranged on the same pitch circle and each swingable, and the inlet guide vanes are attached to one end and the first gear is attached to the other end. A mounting gear, a ring gear that meshes with all of the first gears, and a second gear that meshes with a meshing surface of a ring gear different from a meshing surface with which the first gear meshes A flow control device comprising a formed, lies in having different first gear adjacent the axial position of the first gear.

  In this feature, there are two types of attachment shafts, long and short, and these two types of attachment shafts are arranged adjacent to each other, and the first gear arrangement surface is preferably arranged at two locations in the axial direction. The teeth are formed only on a part of the circumference, and the shape of the first gear may be substantially fan-shaped. Further, the ring gear may mesh with the first gear on the inner peripheral surface and mesh with the second gear on the outer peripheral surface, and the ring gear may have teeth formed only on a part of the outer peripheral surface.

  According to the present invention, since the flow rate adjusting mechanism of the centrifugal compressor has the first gears that are driven gears alternately arranged at different positions in the axial direction, the load transmitted from the first gear to the ring gear is reduced. Thereby, the stress of the 2nd gear which is a drive gear can be reduced, and it can avoid that a centrifugal compressor enlarges, improving the durability of the flow volume adjustment apparatus of a centrifugal compressor.

  Hereinafter, an embodiment and some modifications of a centrifugal compressor according to the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a main part of an embodiment of a centrifugal compressor. FIG. 2 is a perspective view showing a flow rate adjusting mechanism included in the centrifugal compressor shown in FIG.

  As shown in FIG. 1, the centrifugal compressor 10 has a main shaft 11 and a centrifugal impeller 12 attached to the main shaft. A plurality of impellers (not shown) may be attached to the main shaft 11 on the downstream side of the centrifugal impeller 12. In the centrifugal compressor 10, the diaphragm 13 a disposed at the suction side end and the diaphragm 13 b disposed on the shroud side of the impeller 12 are accommodated in the casing 14. The diaphragms 13a and 13b and the casing 14 form a flow path 31 through which the gas guided to the impeller 12 passes.

  The impeller 12 rotates together with the main shaft 11 by a driving device (not shown) that rotates the main shaft 11. When the impeller 12 rotates, the gas that has passed through the flow path 31 is compressed in the impeller 12 by centrifugal force. The compressed gas is guided to a subsequent impeller (not shown) and further compressed. After passing through a discharge port (not shown), the compressed gas is discharged to the outside of the centrifugal compressor 10.

  A plurality of inlet guide vanes 15 oscillating in a plane orthogonal to the main shaft 11 so as to surround the main shaft 11 in the middle of the flow path 31 formed by the diaphragm 13a on the suction end side and the diaphragm 13b on the shroud side. It is arrange | positioned at equal intervals on the circumference. In the present embodiment, the number of inlet guide vanes is 18, but the number is not limited to this. The angle of the inlet guide vane 15 is changed by first gears 17a and 17b included in a flow rate adjusting device, which will be described later, and the gas flowing into the impeller 12 is pre-swiveled. By giving a pre-swirl to the working gas, the working range on the low flow rate region side is expanded.

  Details of the flow control device 30 including the inlet guide vane 15 will be described below. The flow control device 30 has an even number of inlet guide vanes 15. Each inlet guide vane 15 is attached to one end side of attachment shafts 16 a and 16 b arranged in parallel to the main shaft 11. Here, the even-numbered attachment shafts 16a counted from the reference position are formed to have a longer shaft length than the odd-numbered attachment shafts 16b. A first gear 17a is attached to the other end of the even-numbered attachment shaft 16a, and a first gear 17b is attached to the other end of the odd-numbered attachment shaft 16b.

  As shown in FIG. 2, since the axial lengths of the mounting shaft 16a and the mounting shaft 16b are different, the other end sides of the mounting shafts 16a and 16b positioned by the inlet guide vane 15 arranged on one end side of the mounting shaft. The axial positions of are different. That is, the first gear 17b attached to the odd-numbered attachment shaft 16b is located on the rear side, in the axial direction, closer to the impeller 12 than the first gear 17a attached to the even-numbered attachment shaft 16a.

  The attachment shafts 16a and 16b have a central axis on the same pitch circle. The first gears 17a and 17b mesh with the ring gear 18 having the inner teeth 18a formed on the inner peripheral surface while changing the position in the axial direction. The ring gear 18 is disposed coaxially with the main shaft 11. External teeth 18b are formed only on a part of the outer peripheral surface of the ring gear 18, and the second gear 19 is engaged with the external teeth 18b.

  One or at most several second gears 19 are arranged around the ring gear 18. Therefore, only the portion that meshes with the second gear 19 is cut on the outer peripheral side of the ring gear 18, and the man-hour required for gear cutting is reduced. The second gear 19 is attached to one end of the drive shaft 20 that is arranged in parallel to the main shaft.

  The casing 14 that accommodates the diaphragms 13a and 13b has a head flange 14b on the suction side, and the casing 14 and the head flange 14b are fastened by a cap nut 25. A ring-shaped space 14c for accommodating the first gears 17a, 17b, the second gear 19, and the ring gear 18 is formed in a portion of the head flange 14b located on the back side of the diaphragm 13a facing the diaphragm 13a. Yes. Therefore, the attachment shafts 16a and 16b extend from the flow path 31 through the diaphragm 13a to the space 14c, and are rotatably supported by the bearing 13d provided in the diaphragm portion.

  A through hole is formed in the head flange 14b at a position corresponding to the position of the second gear 19, and a holding member that holds the drive shaft 20 with the second gear 19 attached to one end side is formed in the through hole. 14d is fitted. The drive shaft 20 is rotatably supported by a bearing provided on the holding member 14d. The other end side of the drive shaft 20 extends in the axial direction from the holding member 14 d, and the extended end portion is connected to a drive source (not shown) via the gear drive unit 21.

  In the flow control device 30 configured as described above, power is applied from the gear drive unit 21. The applied power is transmitted in the order of the second gear 19, the ring gear 18, and the first gears 17a and 17b, and the angle of the inlet guide vane 15 is changed.

  Here, in the flow rate adjusting device 30 of the centrifugal compressor 10 of the present embodiment, the first gears 17 a and 17 b are arranged on two different arrangement surfaces orthogonal to the main shaft 11 as described above. That is, since the first gears 17a and 17b are arranged on two different surfaces in the axial direction, the first gear 17a and the first gear 17b that are adjacent in the single row arrangement are not adjacent to each other on the same arrangement plane. . The first gear 17a is adjacent to the first gear 17a, and the first gear 17b is adjacent to the first gear 17b.

  As a result, the distance (gap) between the adjacent gears 17a, 17a; 17b, 17b can be made larger than before. Alternatively, it is possible to increase the diameter of the first gears 17a and 17b by an amount corresponding to the increase in distance. When the diameters of the first gears 17a and 17b are increased, the load transmitted from the first gears 17a and 17b to the ring gear 18 is reduced. As a result, the load on the meshing portion between the ring gear 18 and the second gear 19 is reduced, and the durability of the second gear 19 is significantly improved.

  When the inlet guide vane 15 receives a fluctuating load due to fluid force, the first gears 17a and 17b may slightly move and fretting wear may occur at the meshing portion with the ring gear 18. As described above, even when the inlet guide vane 15 is subjected to the fluctuation load by the fluid force, if the flow rate adjusting device shown in the present embodiment is used, the first gears 17a and 17b have a large diameter, and therefore the inertia. Moment increases and fretting wear can be suppressed.

  By the way, in the flow volume control apparatus 30 of a present Example, since the 1st gears 17a and 17b whose diameter was larger than before are used, the module of the 1st gears 17a and 17b can be enlarged. Increasing the modules of the first gears 17a and 17b increases the strength of the gears. Accordingly, the tooth widths of the first gears 17a and 17b can be reduced, and the weight can be reduced.

  Since the first gears 17a and 17b have a larger diameter than before, the space formed between the first gears 17a and 17b and the main shaft 11 is reduced. Depending on the type of centrifugal compressor, the first gears 17a and 17b can be reduced. In some cases, it is difficult to increase the diameter. As the inlet guide vane 15 swings, the positions where the first gears 17a and 17b mesh with the ring gear 18 are changed, but the meshing range does not reach the entire circumference in the circumferential direction. That is, the teeth on the inner diameter side do not mesh with the ring gear 18 at all.

  Therefore, instead of cutting out the entire circumference of the first gears 17a, 17b, as shown in FIG. 3, only the portion that meshes with the ring gear 18 or a fan-shaped first gear cut in consideration of a slight margin. It is also possible to use gears 17c and 17d. When such sector-shaped first gears 17c and 17d are used, a space can be secured on the inner diameter side of the first gears 17c and 17d. Here, the first gear 17c is a gear attached to the long shaft 16a, and the first gear 17b is a gear attached to the short shaft 16b.

  When the fan-shaped first gears 17c and 17d are used, the space between the adjacent gears and 17c and 17c; 17d and 17d becomes wider, so that the diameters of the first gears 17c and 17d can be further increased. In the above embodiment, the first gears 17a to 17d are arranged in two rows in the axial direction. However, the shaft length of the first gear mounting shaft is three or more types, and the first gear is arranged in three or more rows in the axial direction. You may do it. In this case, the structure is a little complicated, but the flow control device 30 can be expected to be downsized.

  In the above embodiments, the first gears 17a to 17d are attached to the two types of long and short shafts 16a and 16b, but the lengths of the shafts to which the first gears 17a to 17d are attached may be the same. However, even in this case, the first gears 17a to 17d need to change their axial mounting positions alternately or according to a certain rule. If the mounting shafts of the first gears 17a to 17d have the same length, there is an advantage that the processing is simplified.

It is a longitudinal cross-sectional view of the principal part of the centrifugal compressor which concerns on this invention. FIG. 2 is a perspective view of a flow rate adjusting device provided in the centrifugal compressor shown in FIG. 1. It is a perspective view of the modification of the flow regulating device concerning the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Centrifugal compressor, 11 ... Main shaft (rotating shaft), 12 ... Impeller, 13 ... Diaphragm, 14 ... Casing, 15 ... Inlet guide vane, 16 ... Mounting shaft, 17 ... First gear, 18 ... Ring gear, 19 2nd gear, 20 ... Drive shaft, 21 ... Gear drive, 30 ... Flow rate adjusting device.

Claims (5)

  A rotating shaft, at least one centrifugal impeller attached to the rotating shaft, a pair of diaphragms defining a flow path upstream of the centrifugal impeller, and the rotating shaft, the centrifugal impeller, and the diaphragm are accommodated. A centrifugal compressor that compresses the sucked gas by rotating the rotary shaft with a driving device, and in the annular flow path formed upstream of the centrifugal impeller on the suction side. A plurality of inlet guide vanes arranged on the same pitch circle and each swingable, an attachment shaft having the inlet guide vanes attached to one end and a first gear attached to the other end, and the first A ring gear meshing with all of the gears and coaxially arranged with the rotary shaft; and a second gear meshing with a meshing surface of a ring gear different from a meshing surface with which the first gear meshes. The amount regulating device is provided, a centrifugal compressor, characterized in that made different in first gear adjacent the axial position of the first gear.   2. The centrifugal according to claim 1, wherein the attachment shaft has two types of long and short, and the two types of attachment shafts are arranged adjacent to each other so that two arrangement surfaces of the first gear are provided in the axial direction. Compressor.   2. The centrifugal compressor according to claim 1, wherein the first gear has teeth formed on only a part of a circumference thereof, and the shape of the first gear is substantially a sector shape.   2. The centrifugal compressor according to claim 1, wherein the ring gear meshes with the first gear on an inner circumferential surface and meshes with a second gear on the outer circumferential surface.   The centrifugal compressor according to claim 4, wherein the ring gear has teeth formed only on a part of an outer peripheral surface thereof.

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