Geared Compressor

Abstract

To suppress vibrations of an intermediate gear even if the size of an impeller connected to a driven gear is different.SOLUTION: A geared compressor is equipped with a driving gear rotated around a driving axis, a first intermediate gear rotated around a first intermediate axis, a second intermediate gear rotated around a second intermediate axis, a first driven gear rotated around a first driven axis, a second driven gear rotated around a second driven axis, a first impeller and a second impeller connected to the first driven gear, and a third impeller and a fourth impeller connected to the second driven gear. When viewed from an axis direction, the driving axis is disposed in a lower part in a vertical direction, with respect to the first intermediate axis, the second intermediate axis, the first driven axis, and the second driven axis. The first impeller has a large diameter as compared with the second impeller, the third impeller, and the fourth impeller.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to geared compressors. [Background technology]

[0002] Centrifugal compressors are known as devices for compressing fluids to generate compressed fluids. One type of centrifugal compressor is a geared compressor, which compresses fluids in stages using multiple impellers via multiple gears. For example, Patent Document 1 (Patent Document 1) describes a geared compressor including a drive gear rotated by a drive source, first and second intermediate gears meshing with the drive gear, a first driven gear meshing with the first intermediate gear, and a second driven gear meshing with the second intermediate gear. The geared compressor of Patent Document 1 has two first-stage compression sections connected to a first driven shaft of the first driven gear, and a second and third compression sections connected to a second driven shaft of the second driven gear. Each compression section has an impeller. The fluid compressed in the two first-stage compression sections flows sequentially through the second and third compression sections, where it is gradually increased in pressure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5863320 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, when two intermediate gears mesh with each other at a distance from the drive gear, one of the two intermediate gears receives a vertically upward load and a horizontally pressing load from the drive gear and the driven gear, respectively. The vertically upward load causes a floating force to act on the intermediate gear. When the vertically upward load and the weight of the intermediate gear are balanced, the horizontally pressing load from the drive gear and the horizontally pressing load from the driven gear are also balanced, causing the intermediate gear to become unstable. In this state, the intermediate gear may rotate at high speed, potentially causing destabilizing vibrations in the intermediate gear. Vibrations in the intermediate gear are particularly pronounced when the sizes of the impellers in the compressor section connected to the driven gear that mesh with the intermediate gear are different at each end.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a geared compressor that can suppress vibration of an intermediate gear even if the sizes of impellers connected to the driven gears are different. [Means for solving the problem]

[0006] In order to solve the above-described problems, a geared compressor according to the present disclosure includes a drive gear that is rotated about a drive axis by rotation of a drive source, a first intermediate gear that meshes with the drive gear and rotates about a first intermediate axis parallel to the drive axis, a second intermediate gear that meshes with the drive gear at a position spaced apart from the first intermediate gear and rotates about a second intermediate axis parallel to the drive axis, a first driven gear that meshes with the first intermediate gear at a position spaced apart from the drive gear and rotates about a first driven axis parallel to the drive axis, a second driven gear that meshes with the second intermediate gear at a position spaced apart from the drive gear and rotates about a second driven axis parallel to the drive axis, and a first impeller and a second impeller connected to one driven gear and compressing a working fluid supplied from the outside by rotation of the first driven gear, and a third impeller and a fourth impeller connected to the second driven gear and compressing a working fluid supplied from the outside by rotation of the second driven gear, wherein when viewed from an axial direction in which the drive axis extends, the drive axis is disposed vertically below the first intermediate axis, the second intermediate axis, the first driven axis, and the second driven axis, and when the working fluid is compressed in order from the first impeller to the fourth impeller, the first impeller has an outer diameter larger than those of the second impeller, the third impeller, and the fourth impeller, When viewed from the axial direction, the first intermediate axis, the second intermediate axis, the first driven axis, and the second driven axis are positioned at the same position in the vertical direction. . [Effects of the Invention]

[0007] According to the geared compressor of the present disclosure, vibration of the rotating shaft can be suppressed even if the impellers connected to the driven gears are of different sizes. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic plan view illustrating a geared compressor according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic diagram illustrating the positional relationship of gears when viewed from the axial direction of a geared compressor according to an embodiment of the present disclosure. [Figure 3]10 is a schematic diagram illustrating a case where the positions of a first driven gear and a second driven gear are shifted relative to the positional relationship of the gears when viewed from the axial direction of the geared compressor according to the embodiment of the present disclosure. FIG. [Figure 4] 10 is a graph showing the relationship between the offset angle of the drive gear relative to the first intermediate gear and the second intermediate gear, and the horizontal force generated between the first intermediate gear, the second intermediate gear, and the drive gear when a load acting vertically upward is balanced with the weights of the first intermediate gear and the second intermediate gear. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of a geared compressor 1 according to the present disclosure will be described with reference to the accompanying drawings. However, the present disclosure is not limited to this embodiment.

[0010] (Configuration of geared compressor) 1 and 2, the geared compressor 1 has a multi-shaft, multi-stage configuration that drives multiple impellers 40. The geared compressor 1 has a drive source 2, a compression section drive mechanism 3, and multiple compression sections 4.

[0011] (Drive source) The driving source 2 generates power for driving the geared compressor 1. For example, a steam turbine can be used as the driving source 2. The output shaft 21 of the driving source 2 is arranged coaxially with a driving axis O1 of a driving gear 31, which will be described later. Therefore, the output shaft 21 of the driving source 2 is rotatable about the driving axis O1.

[0012] (Compression section drive mechanism) The compression unit drive mechanism 3 receives power (torque) generated by the drive source 2 to rotate the impeller 40 of the compression unit 4, which is a device that compresses a working fluid supplied from the outside. The compression unit drive mechanism 3 of this embodiment has a gear case 30, a drive gear 31, a first intermediate gear 32, a second intermediate gear 33, a first driven gear 34, a second intermediate driven gear, multiple radial bearings 51, and multiple thrust bearings 52. The gear case 30 is a casing for accommodating multiple gears therein. The gear case 30 of this embodiment accommodates the drive gear 31, the first intermediate gear 32, the second intermediate gear 33, the first driven gear 34, and the second intermediate driven gear in its internal space.

[0013] The drive gear 31 is housed in a gear case 30. The drive gear 31 is rotated by the rotation of the steam turbine, which is the drive source 2. The drive gear 31 has a drive support shaft 311 and a drive gear body 312. The drive support shaft 311 is formed in a cylindrical shape extending about a drive axis O1 that extends in the horizontal direction Dh.

[0014] In this embodiment, one end of the drive shaft 311 in the axial direction Da is integrally connected to the output shaft 21 of the drive source 2 via a coupling (not shown). Therefore, the drive shaft 311 is rotated around the drive axis O1 by the rotation of the drive source 2.

[0015] In this embodiment, the direction in which the drive axis O1 extends is simply referred to as the "axial direction Da." Furthermore, of both sides of the axial direction Da, one side Da1 (first side) will be simply referred to as the "one side Da1," and the opposite other side Da2 (second side) will be simply referred to as the "other side Da2." In this embodiment, the one side Da1 of the axial direction Da is the side on which the drive source 2 is not arranged relative to the drive support shaft 311. In other words, the other side Da2 of the axial direction Da in this embodiment is the side on which the drive source 2 is arranged relative to the drive support shaft 311.

[0016] The drive spindle 311 is disposed so as to protrude on both sides in the axial direction Da from the drive gear main body 312. An end of the drive spindle 311 on the other side Da2 in the axial direction Da protrudes outside the gear case. The drive spindle 311 is rotatably supported with respect to the gear case by a pair of radial bearings 51 at positions spaced apart from the drive gear main body 312 on one side Da1 and the other side Da2 in the axial direction Da.

[0017] The drive gear body 312 is fixed to the outer periphery of the drive support shaft 311. The drive gear body 312 is, for example, a helical gear that expands from the drive support shaft 311. The drive gear body 312 expands so as to protrude in the vertical direction Dv perpendicular to the drive axis O1 and in the horizontal direction Dh.

[0018] The first intermediate gear 32 is housed in the gear case 30. The first intermediate gear 32 rotates in conjunction with the rotation of the drive gear 31. The first intermediate gear 32 has a first intermediate support shaft 321 and a first intermediate gear main body 322.

[0019] The first intermediate support shaft 321 is formed in a cylindrical shape extending about a first intermediate axis O2 that is parallel to the drive axis O1. The first intermediate support shaft 321 is rotated about the first intermediate axis O2 by the rotation of the drive gear 31. The first intermediate support shaft 321 is disposed so as to protrude on both sides in the axial direction Da from the first intermediate gear main body 322. Both ends of the first intermediate support shaft 321 are rotatably supported with respect to the gear case by a pair of radial bearings 51 at positions spaced apart from the first intermediate gear main body 322 on one side Da1 and the other side Da2 in the axial direction Da.

[0020] The first intermediate gear body 322 meshes with the drive gear body 312. The first intermediate gear body 322 is fixed to the outer periphery of the first intermediate support shaft 321. The first intermediate gear body 322 is, for example, a helical gear that expands from the first intermediate support shaft 321. The first intermediate gear body 322 expands so as to protrude in the vertical direction Dv perpendicular to the first intermediate axis O2 and in the horizontal direction Dh.

[0021] The second intermediate gear 33 is housed in the gear case 30. The second intermediate gear 33 rotates in conjunction with the rotation of the drive gear 31. The second intermediate gear 33 is disposed at a position separated from the first intermediate gear 32. The second intermediate gear 33 has a second intermediate support shaft 331 and a second intermediate gear body 332.

[0022] The second intermediate support shaft 331 is formed in a cylindrical shape extending about a second intermediate axis O3 that is parallel to the drive axis O1 and the first intermediate axis O2. The second intermediate support shaft 331 is rotated about the second intermediate axis O3 by the rotation of the drive gear 31. The second intermediate support shaft 331 is disposed so as to protrude on both sides in the axial direction Da from the second intermediate gear main body 332. Both ends of the second intermediate support shaft 331 are rotatably supported with respect to the gear case by a pair of radial bearings 51 at positions spaced apart from the second intermediate gear main body 332 on one side Da1 and the other side Da2 in the axial direction Da.

[0023] The second intermediate gear body 332 meshes with the drive gear body 312. The second intermediate gear body 332 does not mesh with the first intermediate gear body 322. The second intermediate gear body 332 is fixed to the outer periphery of the second intermediate support shaft 331. The second intermediate gear body 332 is, for example, a helical gear that expands around the second intermediate support shaft 331. The second intermediate gear body 332 expands so as to protrude in the vertical direction Dv perpendicular to the second intermediate axis O3 and in the horizontal direction Dh.

[0024] The first driven gear 34 is housed in the gear case 30. The first driven gear 34 rotates in accordance with the rotation of the first intermediate gear 32. The first driven gear 34 is disposed at a position spaced apart from the drive gear 31 and the second intermediate gear 33. The first driven gear 34 has a first driven support shaft 341 and a first driven gear main body 342. The first driven support shaft 341 is formed in a cylindrical shape extending about a first driven axis O4 that is parallel to the drive axis O1. The first driven support shaft 341 is rotated about the first driven axis O4 by the rotation of the first intermediate gear 32. The first driven support shaft 341 is disposed so as to protrude on both sides in the axial direction Da from the first driven gear main body 342. Both ends of the first driven support shaft 341 are disposed at positions protruding outside the gear case. The first driven support shaft 341 is rotatably supported with respect to the gear case by a pair of radial bearings 51 at positions spaced apart on one side Da1 and the other side Da2 in the axial direction Da from the first driven gear body 342. Furthermore, the first driven support shaft 341 is supported by a thrust bearing 52 on the inside of the pair of radial bearings 51 in the axial direction Da. The thrust bearing 52 has, for example, a thrust collar (not shown) that extends in a disk shape from the outer circumferential surface of the first driven support shaft 341. The thrust bearing 52 restricts movement of the first driven support shaft 341 in the axial direction Da.

[0025] The first driven gear body 342 meshes with the first intermediate gear body 322. The first driven gear body 342 does not mesh with the drive gear body 312 or the second intermediate gear body 332. The first driven gear body 342 is fixed to the outer periphery of the first driven support shaft 341. The first driven gear body 342 is, for example, a helical gear that expands from the first driven support shaft 341 as the center. The first driven gear body 342 expands so as to protrude in the vertical direction Dv perpendicular to the first driven axis O4 and in the horizontal direction Dh.

[0026] The second driven gear 35 is housed in the gear case 30. The second driven gear 35 rotates in conjunction with the rotation of the second intermediate gear 33. The second driven gear 35 is disposed at a position separated from the drive gear 31 and the first intermediate gear 32. The second driven gear 35 has a second driven support shaft 351 and a second driven gear main body 352.

[0027] The second driven shaft 351 is formed in a cylindrical shape extending about a second driven axis O5 parallel to the drive axis O1. The second driven shaft 351 is rotated about the second driven axis O5 by the rotation of the second intermediate gear 33. The second driven shaft 351 is arranged to protrude from the second driven gear main body 352 on both sides in the axial direction Da. Both ends of the second driven shaft 351 are arranged at positions protruding outside the gear case. The second driven shaft 351 is rotatably supported with respect to the gear case by a pair of radial bearings 51 at positions spaced apart from the second driven gear main body 352 on one side Da1 and the other side Da2 in the axial direction Da. Furthermore, the second driven shaft 351 is supported by a thrust bearing 52 inside the pair of radial bearings 51 in the axial direction Da. The thrust bearing 52 restricts the movement of the second driven support shaft 351 in the axial direction Da.

[0028] The second driven gear body 352 meshes with the second intermediate gear body 332. The second driven gear body 352 does not mesh with the drive gear body 312 or the first intermediate gear body 322. The second driven gear body 352 is fixed to the outer periphery of the second driven support shaft 351. The second driven gear body 352 is, for example, a helical gear that expands from the second driven support shaft 351 as the center. The second driven gear body 352 expands so as to protrude in the vertical direction Dv perpendicular to the second driven axis O5 and in the horizontal direction Dh.

[0029] As shown in FIG. 2 , the outer diameter of the drive gear body 312 in this embodiment is smaller than the outer diameters of the first intermediate gear body 322 and the second intermediate gear body 332. Therefore, the number of teeth of the drive gear body 312 is smaller than the number of teeth of the first intermediate gear body 322. Note that the "outer diameter" of a gear in this embodiment may be, for example, the root diameter, tip diameter, or pitch diameter, which can be measured as the distance (dimension) from the center axis of each gear. The outer diameter of the drive gear body 312 is larger than the outer diameters of the first driven gear body 342 and the second driven gear body 352. Therefore, the number of teeth of the drive gear body 312 is greater than the number of teeth of the first driven gear body 342. The outer diameter of the first intermediate gear body 322 is larger than the outer diameter of the first driven gear body 342. Therefore, the number of teeth of the first intermediate gear body 322 is greater than the number of teeth of the first driven gear body 342. The outer diameter of the first intermediate gear body 322 is the same as the outer diameter of the second intermediate gear body 332. Therefore, the number of teeth of the first intermediate gear body 322 is the same as the number of teeth of the second intermediate gear body 332.

[0030] Furthermore, when viewed from the axial direction Da, the first intermediate axis O2, the second intermediate axis O3, the first driven axis O4, and the second driven axis O5 are arranged so that their positions in the vertical direction Dv are the same. That is, when viewed from the axial direction Da, the first driven axis O4 and the second driven axis O5 are arranged on an imaginary horizontal line VH connecting the first intermediate axis O2 and the second intermediate axis O3. The imaginary horizontal line VH is an imaginary straight line extending in the horizontal direction Dh, perpendicular to the vertical direction Dv. Furthermore, when viewed from the axial direction Da, the first intermediate support shaft 321, the second intermediate support shaft 331, the first driven support shaft 341, and the second intermediate support shaft 331 are arranged in parallel so that their positions in the vertical direction Dv overlap.

[0031] In the present embodiment, when viewed from the axial direction Da, the first intermediate axes O2 and the second intermediate axes O3 and the first driven axes O4 and the second driven axes O5 are disposed at the same position in the vertical direction Dv, but the present invention is not limited to such an arrangement. In other words, when viewed from the axial direction Da, the first driven axes O4 and the second driven axes O5 may be disposed so as to be shifted in the vertical direction Dv with respect to the first intermediate axes O2 and the second intermediate axes O3.

[0032] Furthermore, when viewed from the axial direction Da, the drive axis O1 is disposed below the first intermediate axis O2, the second intermediate axis O3, the first driven axis O4, and the second driven axis O5 in the vertical direction Dv. Specifically, when viewed from the axial direction Da, the drive support shaft 311 is disposed below the first intermediate support shaft 321, the second intermediate support shaft 331, the first driven support shaft 341, and the second driven support shaft 351 so as not to overlap their positions in the vertical direction Dv. When viewed from the axial direction Da, the drive support shaft 311 is disposed below the vertical direction Dv so as not to overlap with the imaginary horizontal line VH. When viewed from the axial direction Da, the distance between the drive support shaft 311 and the first intermediate support shaft 321 is the same as the distance between the drive support shaft 311 and the second intermediate support shaft 331. Here, the imaginary line connecting the drive axis O1 and the first intermediate axis O2 is referred to as a first imaginary inclined line VC1. The offset angle of the first imaginary inclined line VC1 with respect to the imaginary horizontal line VH is preferably 15° or more and 35° or less. Furthermore, the offset angle of the first imaginary inclined line VC1 with respect to the imaginary horizontal line VH is more preferably 20° or more and 30° or less. Similarly, the imaginary line connecting the drive axis O1 and the second intermediate axis O3 is referred to as the second imaginary inclined line VC2. The offset angle of the second imaginary inclined line VC2 with respect to the imaginary horizontal line VH is preferably 15° or more and 35° or less. Furthermore, the offset angle of the first imaginary inclined line VC1 with respect to the imaginary horizontal line VH is more preferably 20° or more and 30° or less.

[0033] (Compression section) As shown in FIG. 1 , the compression section 4 compresses the working fluid by being rotated by either a first driven gear 34 or a second driven gear 35. The compression section 4 has an impeller 40 that rotates to compress the working fluid supplied from the outside. A plurality of compression sections 4 are provided. In this embodiment, the geared compressor 1 includes four compression sections 4: a first-stage compression section 41, a second-stage compression section 42, a third-stage compression section 43, and a fourth-stage compression section 44. The number of compression sections 4 in the geared compressor 1 is not limited to four, and may be four or more or four or less.

[0034] The first-stage compression section 41 is connected to the first driven support shaft 341. The first-stage compression section 41 has a first impeller 410 and a scroll casing (not shown). The scroll casing covers the first impeller 410 and has a gas inlet and a gas outlet. The first impeller 410 is fixed to an end of the first driven support shaft 341 on one side Da1 in the axial direction Da. The first impeller 410 compresses the working fluid supplied from the outside by the rotation of the first driven gear 34. The first impeller 410 is formed to be the largest of the multiple impellers 40, when the working fluid is compressed in order from the first impeller 410 to a fourth impeller 440 (described later).

[0035] The second-stage compression section 42 compresses the working fluid compressed in the first-stage compression section 41. The second-stage compression section 42 is connected to the first driven support shaft 341. The second-stage compression section 42 has a second impeller 420 and a scroll casing (not shown). The scroll casing covers the second impeller 420 and has a gas inlet and a gas outlet. The second impeller 420 is fixed to the end of the first driven support shaft 341 on the other side Da2 in the axial direction Da. The second impeller 420 compresses the working fluid supplied from the outside by the rotation of the first driven gear 34. The second impeller 420 is formed to be the second largest of the multiple impellers 40.

[0036] The third-stage compression section 43 compresses the working fluid compressed in the second-stage compression section 42. The third-stage compression section 43 is connected to the second driven support shaft 351. The third-stage compression section 43 has a third impeller 430 and a scroll casing (not shown). The scroll casing covers the third impeller 430 and has a gas inlet and a gas outlet. The third impeller 430 is fixed to an end of the second driven support shaft 351 on one side Da1 in the axial direction Da. The third impeller 430 compresses the working fluid supplied from the outside by the rotation of the second driven gear 35. The third impeller 430 is formed to be the third largest of the multiple impellers 40.

[0037] The fourth-stage compression section 44 compresses the working fluid compressed in the third-stage compression section 43. The fourth-stage compression section 44 is connected to the second driven support shaft 351. The fourth-stage compression section 44 has a fourth impeller 440 and a scroll casing (not shown). The scroll casing covers the fourth impeller 440 and has a gas inlet and a gas outlet. The fourth impeller 440 is fixed to the end of the second driven support shaft 351 on the other side Da2 in the axial direction Da. The fourth impeller 440 compresses the working fluid supplied from the outside by the rotation of the second driven gear 35. The fourth impeller 440 is formed to be the smallest of the multiple impellers 40.

[0038] The first impeller 410, the second impeller 420, the third impeller 430, and the fourth impeller 440 each compress the working fluid drawn into the scroll casing from the gas inlet port while sending it outward in the radial direction of the impeller 40 through a flow path formed therein. The first stage compression section 41, the second stage compression section 42, the third stage compression section 43, and the fourth stage compression section 44 are connected via piping (not shown). As a result, in the geared compressor 1, the working fluid flows through the first stage compression section 41, the second stage compression section 42, the third stage compression section 43, and the fourth stage compression section 44 in this order, thereby compressing the working fluid in stages. Note that a heat exchanger (not shown) may be disposed midway through the piping connecting the first stage compression section 41, the second stage compression section 42, the third stage compression section 43, and the fourth stage compression section 44.

[0039] (Action and effect) In the geared compressor 1 having the above configuration, as shown in FIG. 3 , the first intermediate gear 32 is sandwiched between the drive gear 31 and the first driven gear 34 when viewed from the axial direction Da. As a result, the first intermediate gear 32 receives an upward load in the vertical direction Dv and a load pressing in the horizontal direction Dh (horizontal force Dh) from the drive gear 31 and the first driven gear 34. The upward load in the vertical direction Dv causes a force to act on the first intermediate gear 32 such that it floats up. When the upward load in the vertical direction Dv and the weight of the first intermediate gear 32 are balanced, if the load pressing in the horizontal direction Dh from the drive gear 31 and the load pressing in the horizontal direction Dh from the first driven gear 34 are balanced, the first intermediate support shaft 321 becomes unstable.

[0040] Here, the load acting upward in the vertical direction Dv and the load acting in the horizontal direction Dh are loads generated by the tangential force when moved by an adjacent gear and the reaction force generated when moving the adjacent gear.

[0041] In response to this, the inventors discovered that when a load acting upward in the vertical direction Dv and the weight of the first intermediate gear 32 are balanced, and when a load pressing in the horizontal direction Dh from the drive gear 31 and a load pressing in the horizontal direction Dh from the first driven gear 34 are balanced, the eccentricity ratios of the first intermediate gear 32 relative to the radial bearing 51 in the vertical direction Dv and the horizontal direction Dh approach zero. As the eccentricity ratios of the first intermediate gear 32 in the vertical direction Dv and the horizontal direction Dh approach zero, the gap between the radial bearing 51 supporting the first intermediate support shaft 321 and the first intermediate support shaft 321 becomes uniform over the entire circumference. In this state, when the loads acting on the first intermediate support shaft 321 in the vertical direction Dv and the horizontal direction Dh are balanced and the load acting on the first intermediate support shaft 321 becomes smaller, the first intermediate support shaft 321 will be supported in an unstable state by the radial bearing 51. This is because, in this state, the first intermediate support shaft 321 rotates at high speed, causing unstable vibrations in the first intermediate gear 32.

[0042] 1, the first impeller 410 is formed to be the largest of the multiple impellers 40. In other words, the first driven support shaft 341 has the first impeller 410 connected to one end and the second impeller 420, which is smaller than the first impeller 410, connected to the other end. Therefore, the weights of the impellers 40 supported at both ends of the first driven support shaft 341 are different. As a result, the first driven support shaft 341 is prone to unstable vibrations, which may destabilize the first intermediate support shaft 321.

[0043] However, as shown in FIG. 3 , in the geared compressor 1 having the above-described configuration of this embodiment, the drive gear 31 is disposed so that the drive axis O1 is positioned below the first intermediate axis O2 and the first driven axis O4 in the vertical direction Dv. Therefore, even when a load acting upward in the vertical direction Dv on the first intermediate gear 32 and the weight of the first intermediate gear 32 are balanced, a state can be created in which a load pressed in the horizontal direction Dh from the drive gear 31 and a load pressed in the horizontal direction Dh from the first driven gear 34 are unbalanced. As a result, the first intermediate support shaft 321 can be maintained in a state where it is slightly eccentric in the horizontal direction Dh with respect to the radial bearing 51. This allows the first intermediate support shaft 321 to continue to be stably supported by the radial bearing 51. Furthermore, even when the sizes of the impellers 40 connected to the first driven gear 34 and the second driven gear 35 are different, unstable vibrations in the first intermediate gear 32 can be suppressed.

[0044] Furthermore, when viewed from the axial direction Da, the positions of the first intermediate axis O2, the second intermediate axis O3, the first driven axis O4, and the second driven axis O5 in the vertical direction Dv are the same. Therefore, the positional relationship between the first intermediate gear 32 and the second intermediate gear 33 and the first driven gear 34 and the second driven gear 35 can be made the same. Therefore, the torque transmitted to the first intermediate gear 32 when the load in the vertical direction Dv acting on the first intermediate gear 32 is balanced can be reduced. The reduced transmitted torque allows the load in the vertical direction Dv acting on the first intermediate gear 32 to pass through a balanced state at an early timing after the geared compressor 1 is started and the first intermediate gear 32 begins to rotate. Therefore, when the geared compressor 1 is operating at rated speed, the load in the vertical direction Dv acting on the first intermediate gear 32 is no longer balanced, and unstable vibration in the first intermediate gear 32 can be effectively suppressed.

[0045] Furthermore, if the first driven axis O4 and the second driven axis O5 are disposed above the first intermediate axis O2 and the second intermediate axis O3 in the vertical direction Dv when viewed from the axial direction Da, the torque transmitted to the first intermediate gear 32 when the load in the vertical direction Dv acting on the first intermediate gear 32 is balanced increases. Therefore, it is highly likely that the load in the vertical direction Dv acting on the first intermediate gear 32 will be balanced when the geared compressor 1 is operating at rated speed. As a result, it may not be possible to effectively suppress unstable vibrations in the first intermediate gear 32.

[0046] Furthermore, if the first driven axis O4 and the second driven axis O5 were positioned below the first intermediate axis O2 and the second intermediate axis O3 in the vertical direction Dv when viewed from the axial direction Da, the first driven axis O4 and the second driven axis O5 would be closer to the drive axis O1. Therefore, when the loads in the vertical direction Dv acting on the first intermediate gear 32 and the second intermediate gear 33 are balanced, the load that the first intermediate gear 32 and the second intermediate gear 33 receive from the first driven gear 34 pressing them in the horizontal direction Dh would be reduced. This could result in a smaller amount of eccentricity of the drive support shaft 311 in the horizontal direction Dh relative to the radial bearing 51. As a result, it may not be possible to effectively suppress unstable vibrations in the first intermediate gear 32.

[0047] Therefore, when viewed from the axial direction Da, the unstable vibration of the first intermediate gear 32 can be most effectively suppressed when the positions of the first intermediate axis O2, the second intermediate axis O3, the first driven axis O4, and the second driven axis O5 in the vertical direction Dv are the same.

[0048] Furthermore, the positions of the axes in the vertical direction Dv are limited to only two positions: the position of the drive axis O1 and the position of the first intermediate axis O2. As a result, the structure of the gear case 30 that covers the gears can be simplified.

[0049] 4, when the offset angle is small, the load that the first intermediate gear 32 receives from the drive gear 31 in the horizontal direction Dh when the load in the vertical direction Dv acting on the first intermediate gear 32 is balanced decreases. This may reduce the amount of eccentricity of the drive support shaft 311 in the horizontal direction Dh with respect to the radial bearing 51. As a result, it may not be possible to effectively suppress unstable vibrations in the first intermediate gear 32.

[0050] Furthermore, as the offset angle increases, the load that the first intermediate gear 32 receives in the horizontal direction Dh from the drive gear 31 when the load in the vertical direction Dv acting on the first intermediate gear 32 is balanced can be increased. However, the positions of the drive shaft 311 in the horizontal direction Dh become closer to the first intermediate gear 32 and the second intermediate gear 33. As a result, the positions of the first driven shaft 341 and the second driven shaft 351 in the horizontal direction Dh also become closer. This places a limit on the size of the impeller 40 that can be arranged on the first driven shaft 341 and the second driven shaft 351. Furthermore, if a larger impeller 40 is to be arranged, the first intermediate gear 32 and the second intermediate gear 33 must be made larger. As a result, the machine weight and moment of inertia increase, making it impossible to optimize the compressor drive mechanism 3.

[0051] In contrast to this, by setting the offset angle to be equal to or greater than 15° and equal to or less than 35°, it is possible to ensure a load that presses the first intermediate gear 32 and the second intermediate gear 33 in the horizontal direction Dh from the drive gear 31, while also sufficiently separating the position of the drive support shaft 311 in the horizontal direction Dh from the first intermediate gear 32 and the second intermediate gear 33. This makes it possible to effectively suppress unstable vibrations in the first intermediate gear 32 without being limited by the size of the impeller 40 that can be arranged.

[0052] Furthermore, by setting the offset angle to be equal to or greater than 20° and equal to or less than 30°, unstable vibrations in the first intermediate gear 32 can be more effectively suppressed without being limited by the size of the impeller 40 that can be arranged.

[0053] As shown in FIG. 3 , the outer diameter of the drive gear 31 is smaller than that of the first intermediate gear 32 and the second intermediate gear 33. Furthermore, the outer diameters of the first driven gear 34 and the second driven gear 35 are smaller than that of the drive gear 31. This allows the load applied to the first intermediate gear 32 and the second intermediate gear 33 from the drive gear 31 in the horizontal direction Dh to be greater than the load applied to the first intermediate gear 32 and the second intermediate gear 33 from the first driven gear 34 and the second driven gear 35 in the horizontal direction Dh. As a result, the load applied to the drive gear 31 in the horizontal direction Dh and the load applied to the first driven gear 34 and the second driven gear 35 in the horizontal direction Dh can be reliably offset from each other. This reliably maintains the drive support shaft 311 slightly eccentric in the horizontal direction Dh relative to the radial bearing 51. Therefore, unstable vibrations in the first intermediate gear 32 can be reliably suppressed.

[0054] (Other embodiments) The above describes in detail the embodiments of the present disclosure with reference to the drawings, but the specific configuration is not limited to this embodiment, and design changes and the like are also included within the scope that does not deviate from the gist of the present disclosure.

[0055] The outer diameters of the gears are not limited to those shown in the embodiment. For example, the outer diameter of the first intermediate gear body 322 is not limited to being the same as the outer diameter of the second intermediate gear body 332. The outer diameter of the first intermediate gear body 322 may be larger or smaller than the outer diameter of the second intermediate gear body 332. Furthermore, the outer diameter of the first driven gear body 342 is not limited to being the same as the outer diameter of the second driven gear body 352. Therefore, the outer diameter of the first driven gear body 342 may be larger or smaller than the outer diameter of the second driven gear body 352.

[0056] Furthermore, the size relationship between the impellers 40 is not limited to the shape of the embodiment, as long as the outer diameters of the second impeller 420, the third impeller 430, and the fourth impeller 440 are smaller than the outer diameter of the first impeller 410. The outer diameters of the second impeller 420, the third impeller 430, and the fourth impeller 440 may be the same, or only parts of the second impeller 420, the third impeller 430, and the fourth impeller 440 may have the same outer diameter.

[0057] <Additional Notes> The geared compressor 1 according to the embodiment can be understood, for example, as follows.

[0058] (1) A geared compressor 1 according to a first aspect includes a drive gear 31 that is rotated about a drive axis O1 by rotation of a drive source 2, a first intermediate gear 32 that meshes with the drive gear 31 and rotates about a first intermediate axis O2 that is parallel to the drive axis O1, a second intermediate gear 33 that meshes with the drive gear 31 at a position spaced apart from the first intermediate gear 32 and rotates about a second intermediate axis O3 that is parallel to the drive axis O1, a first driven gear 34 that meshes with the first intermediate gear 32 at a position spaced apart from the drive gear 31 and rotates about a first driven axis O4 that is parallel to the drive axis O1, a second driven gear 35 that meshes with the second intermediate gear 33 at a position spaced apart from the drive gear 31 and rotates about a second driven axis O5 that is parallel to the drive axis O1, and a second driven gear 35 that meshes with the first driven gear 34 at a position spaced apart from the drive gear 31 and rotates about a second driven axis O5 that is parallel to the drive axis O1, and a second driven gear 35 that meshes with the second intermediate gear 33 at a position spaced apart from the drive gear 31 and rotates about a the first driven gear 34 and the second driven gear 35, and compress the working fluid supplied from the outside by the rotation of the second driven gear 35; and the third impeller 430 and the fourth impeller 440, which are connected to the second driven gear 35 and compress the working fluid supplied from the outside by the rotation of the second driven gear 35. When viewed from an axial direction Da in which the drive axis O1 extends, the drive axis O1 is disposed below the first intermediate axis O2, the second intermediate axis O3, the first driven axis O4, and the second driven axis O5 in the vertical direction Dv. When the working fluid is compressed in order from the first impeller 410 to the fourth impeller 440, the first impeller 410 has a larger outer diameter than the second impeller 420, the third impeller 430, and the fourth impeller 440.

[0059] As a result, the drive gear 31 is disposed so that the drive axis O1 is positioned below the first intermediate axis O2 and the first driven axis O4 in the vertical direction Dv. Therefore, even when a load acting upward in the vertical direction Dv on the first intermediate gear 32 is balanced with the weight of the first intermediate gear 32, a state can be maintained in which a load pressed in the horizontal direction Dh from the drive gear 31 and a load pressed in the horizontal direction Dh from the first driven gear 34 are unbalanced. As a result, the first intermediate support shaft 321 can be maintained in a state where it is slightly eccentric in the horizontal direction Dh with respect to the radial bearing 51. This allows the first intermediate support shaft 321 to continue to be stably supported by the radial bearing 51. Furthermore, unstable vibration in the first intermediate gear 32 can be suppressed even when the sizes of the impellers 40 connected to the first driven gear 34 and the second driven gear 35 are different.

[0060] (2) A geared compressor 1 according to a second aspect is the geared compressor 1 of (1), in which, when viewed from the axial direction Da, the positions of the first intermediate axis O2, the second intermediate axis O3, the first driven axis O4, and the second driven axis O5 in the vertical direction Dv are the same.

[0061] This allows the positional relationship between the first intermediate gear 32 and the second intermediate gear 33 and the first driven gear 34 and the second driven gear 35 to be the same. Therefore, it is possible to reduce the torque transmitted to the first intermediate gear 32 when the load in the vertical direction Dv acting on the first intermediate gear 32 is balanced. The reduced transmitted torque allows the load in the vertical direction Dv acting on the first intermediate gear 32 to pass through a balanced state at an early timing after the geared compressor 1 is started and the first intermediate gear 32 begins to rotate. Therefore, when the geared compressor 1 is operating at rated speed, the load in the vertical direction Dv acting on the first intermediate gear 32 is no longer balanced, and unstable vibration in the first intermediate gear 32 can be effectively suppressed.

[0062] (3) A geared compressor 1 according to a third aspect is the geared compressor 1 of (1) or (2), wherein, when viewed from the axial direction Da, an offset angle formed by a first imaginary inclined line VC1 connecting the drive axis O1 and the first intermediate axis O2 with respect to an imaginary horizontal line VH connecting the first intermediate axis O2 and the second intermediate axis O3 is equal to or greater than 15° and equal to or less than 35°.

[0063] This ensures that the first intermediate gear 32 and the second intermediate gear 33 receive a load from the drive gear 31 that presses them in the horizontal direction Dh, while also allowing the drive support shaft 311 to be positioned sufficiently far apart in the horizontal direction Dh from the first intermediate gear 32 and the second intermediate gear 33. This makes it possible to effectively suppress unstable vibrations in the first intermediate gear 32 without being limited by the size of the impeller 40 that can be arranged.

[0064] (4) The geared compressor 1 according to the fourth aspect is any one of the geared compressors 1 according to (1) to (3), in which the outer diameter of the drive gear 31 is smaller than that of the first intermediate gear 32 and the second intermediate gear 33, and the outer diameters of the first driven gear 34 and the second driven gear 35 are smaller than that of the drive gear 31.

[0065] This makes it possible to make the load applied to the first intermediate gear 32 and the second intermediate gear 33 from the drive gear 31 in the horizontal direction Dh larger than the load applied to the first driven gear 34 and the second driven gear 35 in the horizontal direction Dh. As a result, it is possible to reliably offset the load applied to the first intermediate gear 32 and the second intermediate gear 33 in the horizontal direction Dh from the load applied to the first driven gear 34 and the second driven gear 35 in the horizontal direction Dh. This makes it possible to reliably maintain a state in which the drive support shaft 311 is slightly eccentric in the horizontal direction Dh with respect to the radial bearing 51. Therefore, it is possible to reliably suppress unstable vibrations in the first intermediate gear 32. [Explanation of symbols]

[0066] 1...Geared compressor 2...Drive source 21...Output shaft 3...Compression section drive mechanism 30...Gear case 31...Drive gear 311...Drive shaft O1...Drive axis 312...Drive gear body 32...First intermediate gear 321...First intermediate support shaft O2…first intermediate axis 322...First intermediate gear body 33...Second intermediate gear 331...Second intermediate support shaft O3…Second intermediate axis 332...Second intermediate gear body 34...First driven gear 341…First driven support shaft O4…First driven axis 342...First driven gear body 35...Second driven gear 351…Second driven support shaft O5…Second driven axis 352...Second driven gear body VH...virtual horizon VC1: First virtual slope line VC2: Second virtual inclined line 51...Radial bearing 52...Thrust bearing 4...Compression section 40...Impeller 41...First stage compression section 410...First impeller 42...Second stage compression section 420...Second impeller 43...Third stage compression section 430...Third impeller 44...Fourth stage compression section 440...Fourth impeller Da…Axis direction Da1...one side Da2...other side Dv: vertical direction Dh…Horizontal direction

Claims

1. a drive gear that is rotated about a drive axis by rotation of the drive source; a first intermediate gear that meshes with the drive gear and is rotated about a first intermediate axis that is parallel to the drive axis; a second intermediate gear that meshes with the drive gear at a position spaced apart from the first intermediate gear and is rotated about a second intermediate axis that is parallel to the drive axis; a first driven gear that meshes with the first intermediate gear at a position spaced apart from the drive gear and is rotated about a first driven axis that is parallel to the drive axis; a second driven gear that meshes with the second intermediate gear at a position spaced apart from the drive gear and is rotated about a second driven axis that is parallel to the drive axis; a first impeller and a second impeller connected to the first driven gear and configured to compress a working fluid supplied from an external source by rotation of the first driven gear; a third impeller and a fourth impeller connected to the second driven gear and configured to compress a working fluid supplied from an external source by rotation of the second driven gear, When viewed from an axial direction in which the drive axis extends, the drive axis is disposed vertically below the first intermediate axis, the second intermediate axis, the first driven axis, and the second driven axis, When the working fluid is compressed in order from the first impeller to the fourth impeller, the first impeller has an outer diameter larger than those of the second impeller, the third impeller, and the fourth impeller, When viewed from the axial direction, the first intermediate axis, the second intermediate axis, the first driven axis, and the second driven axis are all positioned at the same position in the vertical direction.

2. 2. The geared compressor according to claim 1, wherein, when viewed from the axial direction, an offset angle formed by a first imaginary inclined line connecting the drive axis and the first intermediate axis with respect to an imaginary horizontal line connecting the first intermediate axis and the second intermediate axis is equal to or greater than 15° and is equal to or smaller than 35°.

3. The outer diameter of the drive gear is smaller than the first intermediate gear and the second intermediate gear, 3. The geared compressor according to claim 1, wherein the first driven gear and the second driven gear have outer diameters smaller than that of the drive gear.

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