Method for manufacturing gear box and method for manufacturing method for rotary machine

Abstract

To prevent the body size of a rotary machine from changing while keeping the rotation speed of an impeller the same regardless of the frequency of a power source.SOLUTION: A method for manufacturing a gearbox 10 forms a bull gear 11 and a pinion gear 12 based on a design result determined using a method for designing the gearbox 10. The method for designing the gearbox 10 determines pitch circle diameters A, B of the bull gear 11 and pinion gear 12 so that a rotation speed of the pinion gear 12 remains the same and a distance between the central axes of the bull gear 11 and pinion gear 12 remains the same regardless of a frequency of AC power supplied to a motor.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a gearbox and a method for manufacturing a rotary machine. [Background technology]

[0002] Conventionally, a geared centrifugal compressor is known, as disclosed in Patent Document 1. As disclosed in Patent Document 1, the centrifugal compressor includes a bull gear and a pinion gear. A motor that generates a rotational driving force is connected to the bull gear. The pinion gear meshes with the bull gear and is connected to an impeller. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-119378 Summary of the Invention [Problem to be solved by the invention]

[0004] In a rotary machine in which a bull gear is rotated by a motor supplied with AC power, the rotation speed of the motor changes depending on the frequency of the supplied power. Therefore, in a rotary machine according to the prior art, the rotation speed of the impeller changes depending on the frequency of the supplied power. Therefore, in the prior art, even if the configuration of the bull gear, pinion gear, etc. in the rotary machine is the same, the gas throughput changes simply when the frequency of the power supplied to the motor changes.

[0005] Here, in order to prevent the rotation speed of the impeller from changing even when the frequency of the supplied power changes, it is conceivable to adjust the gear diameter of the bull gear or the gear diameter of the pinion gear.

[0006] However, when the gear diameters of the bull gear, pinion gear, etc. are adjusted to keep the impeller rotation speed constant regardless of frequency, the main body size of the rotary machine changes. That is, when the gear diameters of the bull gear and pinion gear are changed, the distance between the central axis of the bull gear and the central axis of the pinion gear, or the distance between the central axes of multiple pinion gears, may change. When the main body size changes in this way, it is necessary to design the layout of auxiliary parts such as piping for each main body size, which increases manufacturing costs.

[0007] The present invention has been made in view of the above-mentioned problems, and has an object to prevent the main body size of a rotary machine from changing while keeping the impeller rotation speed the same regardless of the frequency of the power supply. [Means for solving the problem]

[0008] A manufacturing method according to one aspect of the present invention is a method for manufacturing a gearbox 10 for a rotary machine 1 for transmitting power from a motor. The gearbox 10 includes a bull gear 11 connected to an input shaft of the motor and a pinion gear 12 meshing with the bull gear 11.

[0009] The manufacturing method according to this aspect includes a reference setting step, a determination step, a step of forming a bull gear 11, and a step of forming a pinion gear 12. In the reference setting step, a reference center axis distance (Ls1) is set, which is the distance between the center axis of the bull gear 11 and the center axis of the pinion gear 12, and which is defined when the frequency of the AC power supplied to the motor is a predetermined frequency. In the reference setting step, a reference rotation speed is set, which is the rotation speed of the pinion gear 12, and which is defined when the frequency of the AC power supplied to the motor is a predetermined frequency.

[0010] In the determination step, when the frequency of the AC power supplied to the motor is different from the predetermined frequency, the pitch circle diameters (A, B) of the bull gear (11) and the pinion gear (12) are determined so as to satisfy the following conditions a1 and a2.

[0011] (Condition a1) The center axis distance, which is the distance between the center axis of the bull gear (11) and the center axis of the pinion gear (12), is set to be the same as the reference center axis distance (Ls1).

[0012] (Condition a2) The rotation speed of the pinion gear (12) is set to be the same as the reference rotation speed.

[0013] In the manufacturing method according to this embodiment, a step of forming the bull gear (11) and a step of forming the pinion gear (12) are carried out using the design results determined through a design process including a reference setting step and the determination step.

[0014] In the manufacturing method of the gearbox 10, even if the rotation speed of the bull gear 11 changes due to a difference in the frequency of the power supply, the rotation speed of the pinion gear 12 can be made the same as the reference rotation speed and the center axis distance can be made the same as the reference center axis distance Ls1, thereby preventing a change in the body size of the rotating machine 1. As a result, it is possible to standardize auxiliary parts such as piping.

[0015] In the manufacturing method according to the above aspect, the gearbox 10 for the rotating machine 1 may further include another pinion gear 13 meshing with the bull gear 11. In this case, the reference setting step may further set a reference center axis distance (Ls2) that is the distance between the center axis of the bull gear 11 and the center axis of the other pinion gear 13 when the frequency of the AC power supplied to the motor is a predetermined frequency. The reference setting step may also set a reference pinion center axis distance (Ls3) that is the distance between the center axis of the pinion gear 12 and the center axis of the other pinion gear 13 when the frequency of the AC power supplied to the motor is a predetermined frequency. The reference setting step may also set a reference rotation speed that is the rotation speed of the other pinion gear 13 when the frequency of the AC power supplied to the motor is a predetermined frequency.

[0016] In the manufacturing method according to this aspect, in the determination step, when the frequency of the AC power supplied to the motor is different from the predetermined frequency, the pitch circle diameter (B2) of the other pinion gear (13) may further be determined so as to satisfy the following conditions b1 and b2.

[0017] (Condition b1) The center axis distance, which is the distance between the center axis of the bull gear (11) and the center axis of the other pinion gear (13), is set to be the same as the reference center axis distance (Ls2).

[0018] (Condition b2) The rotation speed of the other pinion gear (13) is set to be the same as the reference rotation speed.

[0019] Furthermore, in the manufacturing method according to the present aspect, in the determining step, when the frequency of the AC power supplied to the motor is different from the predetermined frequency, the relative positions of the pinion gears (12, 13) may further be determined so as to satisfy the following condition b3:

[0020] (Condition b3) The pinion center axis distance, which is the distance between the center axis of the pinion gear (12) and the center axis of the other pinion gear (13), is set to be the same as the reference pinion center axis distance (Ls3).

[0021] In the manufacturing method of the gearbox 10, even if the rotation speed of the bull gear 11 changes depending on the frequency of the power supply, the size of the main body of the rotary machine 1 can be prevented from changing. As a result, even in manufacturing a gearbox 10 having a plurality of pinion gears 12, 13, it is possible to standardize the piping and other auxiliary parts.

[0022] A manufacturing method according to another aspect of the present invention is a method for manufacturing a gearbox 10 for a rotary machine 1 for transmitting power from a motor. The gearbox 10 includes a bull gear 11 connected to an input shaft of the motor, a pinion gear 12 meshing with the bull gear 11, an idler gear 15 meshing with the bull gear 11, and an idler-side pinion gear 16 meshing with the idler gear 15.

[0023] The manufacturing method according to this embodiment includes a reference setting process, a determination process, a process of forming the bull gear (11), a process of forming the pinion gear (12), a process of forming the idler gear (15), and a process of forming the idler side pinion gear (16).

[0024] In the manufacturing method according to this aspect, the reference setting step sets a reference center axis distance (Ls1) that is the distance between the center axis of the bull gear (11) and the center axis of the pinion gear (12) when the frequency of the AC power supplied to the motor is a predetermined frequency. The reference setting step also sets a reference pinion center axis distance (Ls5) that is the distance between the center axis of the pinion gear (12) and the center axis of the idler-side pinion gear (16) when the frequency of the AC power supplied to the motor is a predetermined frequency. The reference setting step also sets a reference rotation speed that is the rotation speed of the pinion gear (12) when the frequency of the AC power supplied to the motor is a predetermined frequency. The reference setting step also sets another reference rotation speed that is the rotation speed of the idler-side pinion gear (16) when the frequency of the AC power supplied to the motor is a predetermined frequency.

[0025] In the manufacturing method according to this embodiment, in the determination step, when the frequency of the AC power supplied to the motor is different from the predetermined frequency, the pitch circle diameters (A, B1, B3) of the bull gear (11), the pinion gear (12), and the idler side pinion gear (16) are determined so as to satisfy the following conditions c1 and c2.

[0026] (Condition c1) The center axis distance, which is the distance between the center axis of the bull gear (11) and the center axis of the pinion gear (12), is the same as the reference center axis distance (Ls1), and the rotation speed of the pinion gear (12) is the same as the reference rotation speed.

[0027] (Condition c2) The rotational speed of the idler-side pinion gear (16) is set to be the same as the other reference rotational speed.

[0028] In addition, in the determination step, when the frequency of the AC power supplied to the motor is different from the predetermined frequency, the pitch circle diameter (C2) of the idler gear (15) is determined so as to satisfy the following condition c3.

[0029] (Condition c3) The pinion center axis distance, which is the distance between the center axis of the pinion gear (12) and the center axis of the idler side pinion gear (16), is set to be the same as the reference pinion center axis distance (Ls5).

[0030] In the manufacturing method according to this embodiment, the steps of forming the bull gear (11), forming the pinion gear (12), forming the idler gear (15), and forming the idler side pinion gear (16) are carried out using the design results determined through a design process including a reference setting step and the determination step.

[0031] By using the above-described manufacturing method for the gearbox (10), even in the gearbox (10) having an idler side pinion gear (16) with an idler gear (15) interposed between the bull gear (11) and the gearbox (10), it is possible to prevent the main body size of the rotating machine (1) from changing, and to standardize ancillary parts such as piping.

[0032] In the manufacturing method according to the above aspect, the gearbox 10 for the rotating machine 1 may further include another pinion gear 13 meshing with the bull gear 11. In this case, the reference setting step may further set a reference center axis distance (Ls2) that is the distance between the center axis of the bull gear 11 and the center axis of the another pinion gear 13, which is defined when the frequency of the AC power supplied to the motor is a predetermined frequency. Furthermore, the reference setting step may further set a reference pinion center axis distance (Ls3) that is the distance between the center axis of the pinion gear 12 and the center axis of the another pinion gear 13, which is defined when the frequency of the AC power supplied to the motor is a predetermined frequency. The reference setting step may further set a reference pinion center axis distance (Ls6) that is the distance between the center axis of the idler side pinion gear (16) and the center axis of the other pinion gear (13) that is defined when the frequency of the AC power supplied to the motor is a predetermined frequency. The reference setting step may further set a reference rotation speed that is the rotation speed of the other pinion gear (13) that is defined when the frequency of the AC power supplied to the motor is a predetermined frequency.

[0033] In the manufacturing method according to this aspect, in the determination step, when the frequency of the AC power supplied to the motor is different from the predetermined frequency, the pitch circle diameter (B2) of the pinion gear (13) may be determined so as to satisfy the following conditions d1 and d2.

[0034] (Condition d1) The center axis distance, which is the distance between the center axis of the bull gear (11) and the center axis of the other pinion gear (13), is set to be the same as the reference center axis distance (Ls2).

[0035] (Condition d2) The rotation speed of the pinion gear (13) is set to be the same as the reference rotation speed.

[0036] In the manufacturing method according to the present aspect, in the determining step, when the frequency of the AC power supplied to the motor is different from the predetermined frequency, the relative positions of the pinion gears (12, 13) may further be determined so as to satisfy the following condition d3:

[0037] (Condition d3) The pinion center axis distance, which is the distance between the center axis of the pinion gear (12) and the center axis of the other pinion gear (13), is set to be the same as the reference pinion center axis distance (Ls3).

[0038] In the manufacturing method according to the present aspect, in the determination step, when the frequency of the AC power supplied to the motor is different from the predetermined frequency, the pitch circle diameter (C2) of the idler gear (15) may be determined so as to satisfy the following conditions d4 and d5.

[0039] (Condition d4) The pinion center axis distance, which is the distance between the center axis of the pinion gear (12) and the center axis of the idler side pinion gear (16), is set to be the same as the reference pinion center axis distance (Ls5).

[0040] (Condition d5) The pinion center axis distance, which is the distance between the center axis of the other pinion gear (13) and the center axis of the idler side pinion gear (16), is set to be the same as the reference pinion center axis distance (Ls6).

[0041] In the manufacturing method of the gearbox 10, even if the rotation speed of the bull gear 11 changes depending on the frequency of the power supply, it is possible to prevent the main body size of the rotary machine 1 from changing. As a result, even in manufacturing the gearbox 10 including the multiple pinion gears 12, 13, the idler-side pinion gear 16, and the idler gear 15, it is possible to standardize the auxiliary parts such as piping.

[0042] In the manufacturing method according to the above aspect, the gearbox 10 for the rotating machine 1 may further include another idler-side pinion gear 17 that meshes with the idler gear 15. In this case, the reference setting step may further set a reference pinion axis distance Ls7, which is the distance between the center axis of the pinion gear 12 and the center axis of the other idler-side pinion gear 17, defined when the frequency of the AC power supplied to the motor is a predetermined frequency. Furthermore, the reference setting step may further set another reference rotation speed, which is the rotation speed of the other idler-side pinion gear 17, defined when the frequency of the AC power supplied to the motor is a predetermined frequency. Furthermore, in the reference setting process, a reference pinion center axis distance (Ls8) may be set, which is the distance between the center axis of the idler side pinion gear (16) and the center axis of the other idler side pinion gear (17) that is defined when the frequency of the AC power supplied to the motor is a predetermined frequency.

[0043] In the manufacturing method according to this aspect, in the determination step, when the frequency of the AC power supplied to the motor is different from the predetermined frequency, the pitch circle diameter (B4) of the other idler side pinion gear (17) may be determined so as to satisfy the following condition e1:

[0044] (Condition e1) The rotation speed of the other idler-side pinion gear (17) is set to be the same as the other reference rotation speed.

[0045] In the manufacturing method according to the present aspect, in the determining step, when the frequency of the AC power supplied to the motor is different from the predetermined frequency, the pitch circle diameter (C2) of the idler gear (15) may be determined so as to satisfy the following conditions e2 and e3:

[0046] (Condition e2) The pinion center axis distance, which is the distance between the center axis of the pinion gear (12) and the center axis of the idler side pinion gear (16), is set to be the same as the reference pinion center axis distance (Ls5).

[0047] (Condition e3) The pinion center axis distance, which is the distance between the center axis of the pinion gear (12) and the center axis of the other idler side pinion gear (17), is set to be the same as the reference pinion center axis distance (Ls7).

[0048] In the manufacturing method according to the present aspect, in the determining step, when the frequency of the AC power supplied to the motor is different from the predetermined frequency, the relative positions of the idler side pinion gears (16, 17) may further be determined so as to satisfy the following condition e4:

[0049] (Condition e4) The pinion center axis distance, which is the distance between the center axis of the idler side pinion gear (16) and the center axis of the other idler side pinion gear (17), is set to be the same as the reference pinion center axis distance Ls8).

[0050] A method for manufacturing a rotary machine (1) according to one aspect of the present invention includes a step of manufacturing a gearbox (10) by the manufacturing method according to any one of the above aspects.

[0051] In the method for manufacturing the centrifugal compressor (1) according to the above aspect, the gear box (10) is manufactured using the manufacturing method according to the above aspect, and therefore, the same effects as those described above can be obtained.

[0052] In the method for manufacturing the rotary machine (1) according to the above aspect, the rotary machine (1) may be a centrifugal compressor. [Effects of the Invention]

[0053] In each of the above aspects, it is possible to prevent the main body size of the rotary machine from changing while keeping the impeller rotation speed the same regardless of the frequency of the power supply. [Brief explanation of the drawings]

[0054] [Figure 1] 1 is a perspective view showing a partial configuration of a centrifugal compressor manufactured by a manufacturing method according to a first embodiment of the present invention. [Figure 2] FIG. 1 is a process diagram showing a method for designing a gear box and a method for manufacturing a centrifugal compressor. [Figure 3] FIG. 1A is a schematic diagram showing the bull gear and pinion gear when the frequency of the AC power supplied to the motor is a reference frequency, and FIG. 1B is a schematic diagram showing the bull gear and pinion gear when the frequency is different from the reference frequency. [Figure 4] FIG. 6 is a process chart showing a method for designing a gear box and a method for manufacturing a centrifugal compressor according to a modified example of the first embodiment. [Figure 5] FIG. 1A is a schematic diagram showing the bull gear and pinion gear when the frequency of the AC power supplied to the motor is a reference frequency, and FIG. 1B is a schematic diagram showing the bull gear and pinion gear when the frequency is different from the reference frequency. [Figure 6] FIG. 6 is a process chart showing a method for designing a gearbox and a method for manufacturing a centrifugal compressor according to a second embodiment of the present invention. [Figure 7] FIG. 1A is a schematic diagram showing the bull gear and pinion gear when the frequency of the AC power supplied to the motor is a reference frequency, and FIG. 1B is a schematic diagram showing the bull gear and pinion gear when the frequency is different from the reference frequency. [Figure 8] FIG. 10 is a process chart showing a method for designing a gear box and a method for manufacturing a centrifugal compressor according to a modified example of the second embodiment. [Figure 9] FIG. 1A is a schematic diagram showing the bull gear and pinion gear when the frequency of the AC power supplied to the motor is a reference frequency, and FIG. 1B is a schematic diagram showing the bull gear and pinion gear when the frequency is different from the reference frequency. [Figure 10] FIG. 10 is a process chart showing a method for designing a gear box and a method for manufacturing a centrifugal compressor according to another modified example of the second embodiment. [Figure 11] FIG. 10 is a schematic diagram showing a bull gear and a pinion gear when the frequency is different from the reference frequency. DETAILED DESCRIPTION OF THE INVENTION

[0055] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below are merely illustrative of the present invention, and the present invention is not limited to the following embodiments except for the essential configuration.

[0056] [First embodiment] 1. Configuration of centrifugal compressor 1 The configuration of a centrifugal compressor (rotary machine) 1 manufactured using a manufacturing method according to a first embodiment of the present invention will be described with reference to Fig. 1. Note that Fig. 1 shows only a portion of the configuration of the centrifugal compressor 1.

[0057] 1, the centrifugal compressor 1 includes an impeller 40 and a gearbox 10 that transmits a rotational driving force for rotating the impeller 40. The gearbox 10 includes a bull gear 11, a pinion gear 12, and a gear case 14 that covers the outside of these gears 11 and 12.

[0058] The gear case 14 is a case member having an accommodation space 14a that accommodates the bull gear 11 and the pinion gear 12. The gear case 14 has through holes that penetrate the outer wall of the gear case 14 for each of the bull gear 11 and the pinion gear 12. In reality, the gear case 14 is composed of two separate bodies that can be separated into an upper and lower section. The bull gear 11 and the pinion gear 12 are arranged so that their respective shaft portions pass through the through holes of the gear case 14. In other words, the bull gear 11 and the pinion gear 12 are journaled to the gear case 14 via bearings.

[0059] A coupling hub 50 for connecting to a motor 62 is attached to the bull gear 11 outside the gear case 14. The bull gear 11 is rotationally driven by the rotational driving force of the motor 62. The centrifugal compressor 1 of this embodiment employs the motor 62 which is rotationally driven by receiving a supply of AC power.

[0060] The bull gear 11 and the pinion gear 12 are arranged so that their shafts are parallel to each other. The bull gear 11 and the pinion gear 12 are arranged so that their gear portions mesh with each other within the accommodation space 14a of the gear case 14.

[0061] One or two impellers 40 are attached to one or both ends of the pinion gear 12 outside the gear case 14. This also applies to the following embodiments. The impellers 40 are housed in a space defined by the casing 20 and the casing cover 30.

[0062] The space defined by the casing 20 and the casing cover 30 includes a portion for accommodating the impeller 40, a diffuser (not shown) provided radially outward from the impeller 40, and a spiral scroll portion provided further radially outward from the diffuser. Note that the diffuser is not necessarily provided.

[0063] In the centrifugal compressor 1, the gas to which kinetic energy is imparted by the rotation of the impeller 40 is decelerated and pressurized in the diffuser and sent to the scroll section. Note that Fig. 1 shows the centrifugal compressor 1 with parts of the gear case 14, the casing 20, and the casing cover 30 each cut away.

[0064] The casing cover 30 is fastened to the gear case 14 by a fastening member (not shown) at a portion where the shaft portion of the pinion gear 12 extends from the gear case 14.

[0065] A pipe 61 is connected to the casing 20 on the side opposite to the side where the casing cover 30 is attached. The pipe 61 is arranged so that the pipe axis coincides with the central axis Ax12 of the pinion gear 12 at the connection portion with the casing 20. The pipe 61 is attached to the centrifugal compressor 1 as an example of an accessory part.

[0066] As described above, the bull gear 11 and the pinion gear 12 are arranged so that their shaft portions are parallel to each other, and therefore the central axis Ax11 of the bull gear 11 and the central axis Ax12 of the pinion gear 12 are parallel to each other. The same applies to the bull gears and pinion gears in other embodiments.

[0067] Specifically, the pinion gear 12 is arranged such that the center axis Ax12 of the pinion gear 12 is parallel to and spaced apart from the center axis Ax11 of the bull gear 11 by a distance (center axis distance) Ls1.

[0068] In the centrifugal compressor 1 having the above-described configuration, the bull gear 11 rotates when AC power is supplied to the motor 62. The pinion gear 12, which meshes with the bull gear 11 within the accommodation space 14a of the gear case 14, rotates at a rotation speed corresponding to the rotation speed of the bull gear 11. The impeller 40 attached to the tip of the pinion gear 12 rotates at the same rotation speed as the pinion gear 12, imparting kinetic energy to the gas drawn into the space defined by the casing 20 and the casing cover 30.

[0069] 2. Manufacturing method of centrifugal compressor 1 Manufacturing method ST of the centrifugal compressor 1 according to this embodiment MC This will be explained using FIG. 2.

[0070] As shown in FIG. 2, the manufacturing method ST of the centrifugal compressor 1 MC So, how to design a gearbox 10ST D The bull gear 11 and the pinion gear 12 are formed using the design results determined by the above (Step ST5: Manufacturing Method ST of the Gearbox 10) MG Specifically, the bull gear 11 and the pinion gear 12 are formed to have pitch circle diameters determined so as to satisfy conditions 1-1 and 1-2 described below. Next, the bull gear 11 and the pinion gear 12 are assembled to the gear case 14, the impeller 40, and other parts, thereby assembling the centrifugal compressor 1 (step ST6).

[0071] 3. Gearbox 10 design method STD Design method ST for the gearbox 10 according to this embodiment D This will be explained using Figures 2 and 3. Note that only the pitch circle diameter is shown in Figure 3. The same applies to other similar figures.

[0072] 3(a) is a diagram showing the relationship between the bull gear 11 and the pinion gear 12. Design method ST of the gearbox 10 D First, the bull gear 11 and pinion gear 12 are set as references. That is, the design method ST for the gearbox 10 according to this embodiment is D In order to design the gearbox 10 so that the rotation speed of the impeller 40 remains the same regardless of the frequency of the AC power supplied to the motor 63 and the center axis distance is the same as the reference center axis distance Ls1, first, the reference bull gear 11 and pinion gear 12 are set.

[0073] The reference bull gear 11 is set to rotate at a predetermined rotation speed when the frequency of AC power supplied to the motor 62 is a predetermined frequency fs (for example, 50 Hz). The reference pinion gear 12 is set to mesh with the reference bull gear 11 (to have the same module).

[0074] In the following description, the predetermined frequency fs, which is defined when setting the bull gear 11 and pinion gear 12 as the reference, will be referred to as the "reference frequency fs."

[0075] In FIG. 3(a), the pitch circle of the bull gear 11 is indicated by 11c. The pitch circle of the pinion gear 12 is indicated by 12c. The diameter of the pitch circle 11c at the reference frequency fs is designated as "As" (hereinafter referred to as "reference pitch circle diameter As"). The diameter of the pitch circle 12c at the reference frequency fs is designated as "Bs" (hereinafter referred to as "reference pitch circle diameter Bs"). The center axis distance, which is the distance between the center axis of the bull gear 11 and the center axis of the pinion gear 12 at the reference frequency fs, is designated as "Ls1" (hereinafter referred to as "reference center axis distance Ls1").

[0076] Here, when the bull gear 11 is rotated at a predetermined rotation speed Nbs by the motor 62 supplied with AC power of the reference frequency fs, the reference pitch circle diameter Bs is set so that the rotation speed of the pinion gear 12 (which is also the rotation speed of the impeller 40 attached to the pinion gear 12) rotates at the predetermined rotation speed Nps. Note that, hereinafter, Nbs and Nps will be referred to as the "reference rotation speed Nbs" and the "reference rotation speed Nps", respectively.

[0077] As shown in Figure 2, the design method of the gearbox 10 D First, in step ST1 (a reference setting step), reference pitch circle diameters As and Bs, reference rotational speeds of the bull gear 11 and pinion gear 12, and reference center axis distance Ls1 are set.

[0078] Next, it is determined whether or not the frequency f of the power input to the attached motor 62 is the same as the reference frequency fs in the specifications of the gearbox 10 to be designed (step ST2).

[0079] If the frequency f is the same as the reference frequency fs (step ST2: NO), the bull gear 11 and the pinion gear 12 are designed using the reference pitch circle diameters As and Bs (step ST4: determination step). MC Steps ST5 and ST6 are executed.

[0080] Next, a case where frequency f is different from reference frequency fs (for example, 60 Hz) will be described (step ST2: YES). In the following description, frequency f will be referred to as "target frequency ft" when it is to be distinguished from reference frequency fs. Figure 3(b) is a diagram showing the relationship between bull gear 11 and pinion gear 12 at target frequency ft.

[0081] In Figure 3(b), in the gearbox 10 to be designed, the diameter (pitch circle diameter) of the pitch circle 11c of the bull gear 11 at the target frequency ft is indicated by "A", and the diameter (pitch circle diameter) of the pitch circle 12c of the pinion gear 12 is indicated by "B". The pitch circle diameters A and B of the bull gear 11 and pinion gear 12 at the target frequency ft are determined based on the following conditions 1-1 and 1-2.

[0082] (Condition 1-1) The distance between the centers of the bull gear 11 and the pinion gear 12 is the same as the reference distance between the centers Ls1 set in step ST1.

[0083] Therefore, the following relationship holds between the pitch circle diameters As and Bs of the bull gear 11 and pinion gear 12 at the reference frequency fs and the pitch circle diameters A and B of these at the target frequency ft.

[0084] A+B=As+Bs (Equation 1-1) (Condition 1-2) The rotation speed Np of the pinion gear 12 at the target frequency ft is the same as the reference rotation speed Nps set in step ST1, and the rotation speed Nb of the bull gear 11 is (ft / fs)×Nbs.

[0085] Therefore, Nb / Np = (ft / fs)Nbs / Nps. Also, when the speed transmission ratio is taken into consideration, Nb / Np = B / A holds between the rotation speed and pitch circle diameter of the bull gear 11 and pinion gear 12 when the target frequency is ft, and Nbs / Nps = Bs / As holds when the reference frequency is fs, leading to the following relationship:

[0086] (B / A)=(ft / fs)×(Bs / As) (Formula 1-2) The pitch circle diameters A and B of the bull gear 11 and the pinion gear 12 can be determined based on Equations 1-1 and 1-2 (Step ST3: Determination step). Note that the pitch circle diameters A and B may be finely adjusted based on the helix angles and addendum modification coefficients of the bull gear 11 and the pinion gear 12 (the same applies to the other embodiments).

[0087] The determination of the pitch circle diameters A and B in step ST3 is based on the premise that the frequency f of the power input to the motor 62 is different from the reference frequency fs, but other design conditions are the same (typically, the same model). Therefore, in the actual design of the gearbox 10, other design conditions such as the processing air volume may also be taken into consideration.

[0088] In addition, the design method ST for the gearbox 10 according to this embodiment D The distance between the central axes of the bull gear 11 and the pinion gear 12 formed based on the above does not need to be strictly the same as the reference central axis distance Ls1. The rotation speed of the pinion gear 12 does not need to be strictly the same as the reference rotation speed Nps.

[0089] 4.Effects Manufacturing method ST of the gearbox 10 according to this embodiment MC In this case, even if the frequency of the power supply (the frequency of the AC power supplied to the motor 62) is a frequency f different from the reference frequency fs, the pitch circle diameters A and B are determined so as to satisfy the above conditions 1-1 and 1-2, and the results are used to form the bull gear 11 and each pinion gear 12 (execute step ST5). MC In this case, even if the rotation speed of the bull gear 11 changes due to differences in the frequency of the power supply, the rotation speed Np of the impeller 40 can be made the same as the reference rotation speed Nps, and the center axis distance between the bull gear 11 and the pinion gear 12 can be made the same as the reference center axis distance Ls1. Therefore, in the manufacturing method ST for the gearbox 10 according to this embodiment, MC In this case, it is possible to prevent the main body size of the centrifugal compressor 1 equipped with the gearbox 10 from changing, and it is possible to standardize the auxiliary parts such as the piping 61. The relative position between the piping 61 and the motor 62 can also be made the same regardless of the frequency of the AC power supplied to the motor 62.

[0090] [Modification of the first embodiment] Design method ST for the gearbox 10 according to a modification of the first embodiment DThis will be described with reference to FIG. 4. D 4, the same configuration as that of the first embodiment is adopted. The gearbox 10 according to this modification is also incorporated as a part of the centrifugal compressor 1, similarly to the first embodiment.

[0091] 5(a) is a diagram showing the relationship between the bull gear 11 and the pinion gears 12 and 13 at the reference frequency fs. D In the gearbox 10 designed by the present invention, in addition to the pinion gear 12, another pinion gear 13 that meshes with the bull gear 11 is arranged at a 90-degree angle. The arrangement of the pinion gears 12 and 13 relative to the bull gear 11 may be set arbitrarily. Although not shown in the drawings, an impeller 40 is also connected to the pinion gear 13.

[0092] In Figure 5(a), the reference pitch diameter of the pitch circle 11c of the bull gear 11 is indicated by "As1". The reference pitch diameter of the pitch circle 12c of the pinion gear 12 is indicated by "Bs1". The reference center axis distance between the bull gear 11 and the pinion gear 12 is indicated by "Ls1". The reference pitch diameter of the pitch circle 13c of the pinion gear 13 is indicated by "Bs2". The reference center axis distance between the center axis of the bull gear 11 and the center axis of the pinion gear 13 is indicated by "Ls2". The pinion center axis distance, which is the distance between the center axis of the pinion gear 12 and the center axis of the pinion gear 13, is indicated by "Ls3" (hereinafter referred to as the "reference pinion center axis distance Ls3").

[0093] Here, the reference pitch circle diameter Bs1 of the pinion gear 12 and the reference pitch circle diameter Bs2 of the pinion gear 13 are set so that when the bull gear 11 rotates at a predetermined rotation speed Nbs by the motor 62 having the reference frequency fs, the pinion gears 12 and 13 rotate at the reference rotation speed Nps1 and the reference rotation speed Nps2, respectively.

[0094] As shown in Figure 4, the design method of the gearbox 10 DIn step ST11 (reference setting step), reference pitch diameters As, Bs1, Bs2, reference rotational speeds Nbs, Nps1, Nps2 of the bull gear 11 and pinion gears 12, 13, reference center axis distances Ls1, Ls2, and reference pinion center axis distance Ls3 are set.

[0095] Next, it is determined whether the frequency f of the power input to the motor 62 is the same as the reference frequency fs (step ST2).

[0096] If the frequency f is the same as the reference frequency fs (step ST2: NO), the bull gear 11 and the pinion gears 12 and 13 are designed using the preset reference pitch circle diameters As, Bs1, and Bs2 (step ST41: determination step). MC Steps ST5 and ST6 (see FIG. 2) are executed.

[0097] Next, a case where frequency f (e.g., 60 Hz) is different from reference frequency fs will be described (step ST2: YES). In the following description, frequency f will be referred to as target frequency ft when it is to be distinguished from reference frequency fs. Figure 5(b) is a diagram showing the relationship between bull gear 11 and pinion gears 12, 13 at target frequency ft.

[0098] The pitch circle diameters A and B1 of the bull gear 11 and any one of the pinion gears 12 at the target frequency ft are determined based on the following conditions 2-1 and 2-2, which are the same as the above-mentioned conditions 1-1 and 1-2.

[0099] (Condition 2-1) The distance between the centers of the bull gear 11 and the pinion gear 12 is the same as the reference distance between the centers Ls1 set in step ST1.

[0100] (Condition 2-2) The rotation speed Np1 of the pinion gear 12 at the target frequency ft is the same as the reference rotation speed Nps1 referred to in step ST1, and the rotation speed Nb of the bull gear 11 is (ft / fs)×Nbs.

[0101] Therefore, the following equations 2-1 and 2-2 hold true.

[0102] A+B1=As+Bs1 (Formula 2-1) (B1 / A)=(ft / fs)×(Bs1 / As) (Formula 2-2) The pitch circle diameters A and B1 of the bull gear 11 and the pinion gear 12 are determined based on the formulas 2-1 and 2-2.

[0103] Furthermore, the following conditions 2-3 and 2-4, which are similar to the conditions 2-1 and 2-2, are set between the bull gear 11 and the pitch circle diameters A and B2 of the other pinion gears 13 at the target frequency ft.

[0104] (Condition 2-3) The distance between the central axes of the bull gear 11 and the other pinion gears 13 is the same as the reference distance between the central axes Ls2 referred to in step ST1.

[0105] (Condition 2-4) The rotation speed Np2 of the other pinion gears 13 at the target frequency ft is the same as the reference rotation speed Nps2 referred to in step ST1, and the rotation speed Nb of the bull gear 11 is (ft / fs)×Nbs.

[0106] Based on condition 2-3, equation 2-3, which is similar to equation 2-1, holds.

[0107] A+B2=As+Bs2 (Equation 2-3) The pitch circle diameter B2 of the other pinion gear 13 can be determined based on the pitch circle diameter A of the bull gear 11 calculated by equations 2-1 and 2-2 and equation 2-3.

[0108] Furthermore, since equation 2-4 similar to equation 2-2 holds based on condition 2-4, the pitch circle diameter A of the bull gear 11 calculated by equations 2-1 and 2-2 and the pitch circle diameter B2 of the other pinion gear 13 may be determined based on equation 2-4.

[0109] (B2 / A)=(ft / fs)×(Bs2 / As) (Formula 2-4) (Condition 2-5) The pinion center axis distance, which is the distance between the center axes of the two pinion gears 12, 13, is the same as the reference pinion center axis distance Ls3.

[0110] Based on the conditions 2-5, the arrangement of the pinion gears 12 and 13 is determined so that the relative positions between them are the same as in the case of the reference frequency fs (step ST31: determining step).

[0111] As described above, the design method ST for the gearbox 10 according to this modified example D and manufacturing method ST MG ,ST MC In this regard, it is possible to prevent the main body size of the centrifugal compressor 1 equipped with the gear box 10 from changing, and it is possible to standardize the auxiliary parts such as the piping 61.

[0112] In the modified example of the first embodiment, the design method ST for the gearbox 10 according to the above aspect can also be used in the manufacture of a gearbox 10 having three or more pinion gears that mesh with the bull gear 11. D can be applied. In the following description, only differences from the design method described using FIG. 4 will be described. The rest of the design method is the same as that shown in FIG. 4. That is, in step ST32 (determination step), the pitch diameter of each pinion gear can be determined based on an equation similar to equation 2-3 for each pinion gear and the pitch diameter A of the bull gear 11 calculated using equations 2-1 and 2-2. Furthermore, similar to condition 2-5, the relative position of each pinion gear is determined so that multiple pinion center axis distances between the multiple pinion gears are the same as multiple reference pinion center axis distances at the reference frequency fs. For example, when three pinion gears are provided, the relative position of each pinion gear is determined so that the pinion center axis distances between the first pinion gear and the second pinion gear, between the second pinion gear and the third pinion gear, and between the third pinion gear and the first pinion gear are the same as the reference pinion center axis distances at the corresponding reference frequency fs. This makes it possible to prevent the main body size of the centrifugal compressor 1 from changing even when the frequency of the power supply changes.

[0113] [Second embodiment] Manufacturing method ST for a gearbox 10 according to a second embodiment of the present invention MG and design method ST D and the manufacturing method ST of the centrifugal compressor 1 MC This will be described with reference to Figures 6 and 7. The centrifugal compressor 1 has the same configuration as that of the first embodiment except for the configuration shown in Figure 7.

[0114] 1. Gearbox 10 configuration As shown in FIG. 7(a), the manufacturing method ST according to this embodiment MG The gearbox 10 to be manufactured using the above includes a bull gear 11, pinion gears 12 and 16, and an idler gear 15. The pinion gear 12 is a gear that meshes with the bull gear 11. The pinion gear 16 is a pinion gear that indirectly meshes with the bull gear 11 via the idler gear 15. Hereinafter, the pinion gear 16 will be referred to as the "idler-side pinion gear 16." One or two impellers 40 are attached to one or both ends of each of the pinion gear 12 and the idler-side pinion gear 16, outside the gear case 14. The idler gear 15 and the idler-side pinion gear 16 are also journaled to the gear case 14 (see FIG. 1) via bearings.

[0115] 2. Manufacturing method of centrifugal compressor 1 As shown in FIG. 6, a manufacturing method ST for the centrifugal compressor 1 according to this embodiment MC How to design a gearbox 10 ST D Using the design results determined by the above, the bull gear 11, pinion gear 12, idler-side pinion gear 16, and idler gear 15 are formed (step ST52). Next, the bull gear 11, pinion gear 12, idler-side pinion gear 16, and idler gear 15 are assembled to the gear case 14, the impeller 40, and other parts, thereby assembling the centrifugal compressor 1 (step ST6).

[0116] 3. Gearbox 10 design method ST D How to design a gearbox 10ST D Then, in step ST12 (reference setting step), reference pitch circle diameters As, Bs1, and Bs3 of the bull gear 11, pinion gear 12, and idler-side pinion gear 16 at the reference frequency fs are set. Furthermore, reference rotation speeds of the bull gear 11, pinion gear 12, and idler-side pinion gear 16 are set. A reference center axis distance Ls1 and a reference pinion center axis distance Ls5 are set. A pitch circle diameter C1 of the idler gear 15 is set.

[0117] FIG. 7(a) is a diagram showing the relationship between the bull gear 11, the pinion gear 12, the idler-side pinion gear 16, and the idler gear 15 at the reference frequency fs.

[0118] The reference bull gear 11 is set to rotate at a predetermined rotation speed when the frequency of the AC power supplied to the motor 62 is a predetermined reference frequency fs (for example, 50 Hz).

[0119] In FIG. 7(a), the pitch circle of the bull gear 11 is indicated by 11c. The diameter (reference pitch diameter) of the pitch circle 11c is indicated by "As". The pitch circles of the pinion gear 12 and the idler-side pinion gear 16 are indicated by 12c and 16c. The diameters (reference pitch diameters) of the pitch circles 12c and 16c are indicated by "Bs1" and "Bs3", respectively. The reference center axis distance between the bull gear 11 and the pinion gear 12 is indicated by "Ls1", as in the first embodiment. The reference center axis distance between the bull gear 11 and the idler-side pinion gear 16 is indicated by "Ls4". The reference pinion center axis distance between the pinion gear 12 and the idler-side pinion gear 16 is indicated by "Ls5". The pitch circle diameter of the idler gear 15 at the reference frequency fs is indicated by "C1".

[0120] In this embodiment, the reference pitch diameters Bs1 and Bs3 of the pinion gear 12 and the idler side pinion gear 16 are set so as to rotate at a predetermined reference rotation speed NPs1 and a reference rotation speed (reference rotation speed of the idler side impeller 40 connected to the idler side pinion gear 16) Nps3, respectively, relative to the reference rotation speed Nbs of the bull gear 11 at the reference frequency fs.

[0121] As shown in Figure 6, the design method of the gearbox 10 D If the frequency f is the same as the reference frequency fs (step ST2: NO), the bull gear 11, pinion gear 12, and idler-side pinion gear 16 are designed using the preset reference pitch circle diameters As, Bs1, and Bs3, and the idler gear 15 is designed using the pitch circle diameter C1 (step ST42: determination step). MC Steps ST52 and ST6 are executed.

[0122] Next, a case where the frequency f is different from the reference frequency fs (for example, 60 Hz) will be described (step ST2: YES). Fig. 7(b) is a diagram showing the relationship between the bull gear 11, the pinion gear 12, the idler-side pinion gear 16, and the idler gear 15 at a target frequency ft, which is a frequency f different from the reference frequency fs.

[0123] In Figure 7(b), in the gearbox 10 to be designed, the pitch circle diameter of the bull gear 11 at the target frequency ft is indicated by "A", and the pitch circle diameters of the pinion gear 12 and idler-side pinion gear 16 are indicated by "B1" and "B3". The pitch circle diameter of the idler gear 15 is indicated by "C2". The pitch circle diameters A, B1, B3, and C2 are determined based on the following conditions 3-1 to 3-4.

[0124] (Condition 3-1) The distance between the centers of the bull gear 11 and the pinion gear 12 is the same as the reference distance between the centers Ls1 set in step ST11.

[0125] Therefore, the following relationship holds true, as in the first embodiment.

[0126] A+B1=As+Bs1 ···(Formula 3-1) (Condition 3-2) The rotation speed Np1 of the pinion gear 12 at the target frequency ft is the same as the reference rotation speed Nps1, and the rotation speed Nb of the bull gear 11 is (ft / fs)×Nbs.

[0127] Therefore, the following relationship holds true, as in the first embodiment.

[0128] (B1 / A)=(ft / fs)×(Bs1 / As) (Formula 3-2) The pitch circle diameters A and B1 of the bull gear 11 and the pinion gear 12 are determined based on the formulas 3-1 and 3-2.

[0129] (Condition 3-3) The rotation speed Np3 of the idler-side pinion gear 16 at the target frequency ft is the same as the reference rotation speed Nps3 referred to in step ST1.

[0130] Therefore, the following relationship is derived between the idler side pinion gear 16 and the bull gear 11:

[0131] (B3 / A)=(ft / fs)×(Bs3 / As) (Formula 3-3) The pitch circle diameter B3 of the idler-side pinion gear 16 is determined based on the formula 3-3 and the pitch circle diameter A of the bull gear 11 determined based on the formulas 3-1 and 3-2.

[0132] (Condition 3-4) The pinion center axis distance between the pinion gear 12 and the idler side pinion gear 16 is the same as the reference pinion center axis distance Ls5.

[0133] Based on condition 3-4, the pitch circle diameter C2 of the idler gear 15 is determined so that the relative position between the pinion gear 12 and the idler-side pinion gear 16 is fixed (step ST32: determination step). Note that the pitch circle diameter C2 may be the same as C1. The position of the central axis of the idler gear 15 may deviate from the position of the central axis of the idler gear 15 in the reference setting step.

[0134] 4.Effects Manufacturing method ST of the gearbox 10 according to this embodiment MG In this case, even if the rotation speed of the bull gear 11 changes due to differences in the frequency of the power supply, the rotation speeds of the pinion gear 12 and the idler-side pinion gear 16 can be made the same as the reference rotation speeds Nps1 and Nps3, while the pinion center axis distance between the pinion gear 12 and the idler-side pinion gear 16 can be made the same as the reference pinion center axis distance Ls5. The relative position between the pinion gear 12 and the idler-side pinion gear 16 can also be made the same. Therefore, the manufacturing method ST for the gearbox 10 according to this embodiment MG In this case, it is possible to prevent the main body size of the centrifugal compressor 1 from changing, and it is possible to standardize the layout of the auxiliary parts such as the piping 61.

[0135] Design method ST according to this embodiment D In a manufacturing method of a gearbox 10 having a plurality of idler gears, the above method can be used to determine the pitch diameter and rotation speed of the idler-side pinion gear that meshes with each idler gear, as well as to determine the relative position between the pinion gear 12 and the idler-side pinion gear.

[0136] [Modification of the second embodiment] Design method ST for the gearbox 10 according to the modified example of the second embodiment D This will be explained with reference to FIG.

[0137] 9(a) is a diagram showing the relationship between the bull gear 11, the pinion gears 12 and 13, the idler-side pinion gear 16, and the idler gear 15 at the reference frequency fs. DIn the gearbox 10 designed by the present invention, two pinion gears 12 and 13 are arranged with a 90-degree offset from each other relative to the bull gear 11. Other configurations are the same as those of the second embodiment. The arrangement of the pinion gears 12 and 13 relative to the bull gear 11 may be set arbitrarily. Although not shown in the drawings, an impeller 40 is connected to each of the pinion gears 12 and 13 and the idler-side pinion gear 16.

[0138] How to design a gearbox 10ST D First, in step ST12 (reference setting step) shown in Fig. 8, reference pitch circle diameters As, Bs1, Bs2, and Bs3 of the bull gear 11, pinion gears 12 and 13, and idler-side pinion gear 16 at the reference frequency fs are set. Reference rotation speeds of the bull gear 11, pinion gears 12 and 13, and idler-side pinion gear 16 are set. A pitch circle diameter C1 of the idler gear 15 is set.

[0139] Also, reference center axis distances Ls1 and Ls2 are set between the bull gear 11 and the pinion gears 12 and 13. Furthermore, in this modified example, as shown in Fig. 9(a), a plurality of types of reference pinion center axis distances are set, and specifically, a reference pinion center axis distance Ls3 (first type) between the pinion gears 12 and 13 that mesh with the bull gear 11, and reference pinion center axis distances Ls5 and Ls6 (second type) between the pinion gears 12 and 13 and the idler-side pinion gear are set.

[0140] Next, it is determined whether the frequency f of the power is the same as the reference frequency fs (step ST2). If the frequency f is the same as the reference frequency fs (step ST2: NO), the bull gear 11, pinion gears 12, 13, and idler-side pinion gear 16 are designed using the reference pitch circle diameters As, Bs1, Bs2, and Bs3, and the idler gear 15 is designed using the pitch circle diameter C1 (step ST43: determination step). Then, the manufacturing method ST MC Steps ST52 and ST6 (see FIG. 6) are executed.

[0141] Next, a case where frequency f (e.g., 60 Hz) is different from reference frequency fs will be described (step ST2: YES). Fig. 9(b) is a diagram showing the relationship between bull gear 11, pinion gears 12 and 13, idler-side pinion gear 16, and idler gear 15 at target frequency ft, which is frequency f different from reference frequency fs. Each pitch circle diameter A, B1, B2, B3, and C2 is determined based on the following conditions 4-1 to 4-5.

[0142] (Condition 4-1) The center axis distance between the bull gear 11 and the pinion gear 12 is the same as the reference center axis distance Ls1 referred to in step ST12.

[0143] Therefore, the following relationship holds true, as in the first embodiment.

[0144] A+B1=As+Bs1 (Formula 4-1) (Condition 4-2) The rotation speed Np1 of the pinion gear 12 at the target frequency ft is the same as the reference rotation speed Nps, and the rotation speed Nb of the bull gear 11 is (ft / fs)×Nbs.

[0145] Therefore, the following relationship holds true, as in the first embodiment.

[0146] (B1 / A)=(ft / fs)×(Bs1 / As) (Formula 4-2) (Condition 4-3) The center axis distance between the bull gear 11 and the other pinion gears 13 is the same as the reference center axis distance Ls2 referred to in step ST1.

[0147] (Condition 4-4) The rotation speed Np2 of the other pinion gears 13 at the target frequency ft is the same as the reference rotation speed Nps2 referred to in step ST1, and the rotation speed Nb of the bull gear 11 is (ft / fs)×Nbs.

[0148] Based on condition 4-3, equation 4-3, which is similar to equation 4-1, holds.

[0149] A+B2=As+Bs2 (Equation 4-3) The pitch circle diameters A, B1, and B2 can be determined based on the formulas 4-1 to 4-3. Note that, since the formula 4-4, which is similar to the formula 4-2, is established based on the condition 4-4, the formula 4-4 may be used instead of the formula 4-3.

[0150] (B2 / A)=(ft / fs)×(Bs2 / As) (Formula 4-4) (Condition 4-5) The distance between the pinion central axes of the two pinion gears 12, 13 is the same as the reference pinion central axis distance Ls3.

[0151] The arrangement of the pinion gears 12 and 13 is determined so that the relative positions between them are fixed based on conditions 4-5.

[0152] (Condition 4-6) The rotation speed Np3 of the idler-side pinion gear 16 at the target frequency ft is the same as the reference rotation speed Nps3 at the reference frequency fs.

[0153] Therefore, the following relationship is derived between the idler side pinion gear 16 and the bull gear 11:

[0154] (B3 / A)=(ft / fs)×(Bs3 / As) (Formula 4-5) The pitch circle diameter B3 of the idler side pinion gear 16 can be determined based on equation 4-5 and the pitch circle diameter A determined based on equations 4-1 to 4-3. Note that equation 4-6 may be used instead of equation 4-5, based on the condition that the center axis distance between the bull gear 11 and the idler side pinion gear 16 is the same as the reference center axis distance Ls4.

[0155] As+Bs3=A+B3 (Equation 4-6) (Condition 4-7) The pinion center axis distances between the pinion gear 12 and the idler side pinion gear 16 and between the pinion gear 13 and the idler side pinion gear 16 are the same as the reference pinion center axis distances Ls5 and Ls6, respectively.

[0156] Based on conditions 4-7, the pitch circle diameter C2 of the idler gear 15 is determined so that the relative positions between the pinion gears 12, 13 and the idler-side pinion gear 16 are fixed (step ST33: determination step). Note that the pitch circle diameter C2 may be the same as C1. The position of the central axis of the idler gear 15 may deviate from the position of the central axis of the idler gear 15 in the reference setting step.

[0157] Manufacturing method ST of the gearbox 10 according to this embodiment MG Even in this case, it is possible to prevent the main body size of the centrifugal compressor 1 from changing, and it is possible to standardize the layout of auxiliary parts such as the piping 61.

[0158] In a modification of the second embodiment, three or more pinion gears may be provided that mesh with the bull gear 11. If the target frequency ft is different from the reference frequency fs (step ST2: YES), in step ST33 (determination step), the pitch diameter of each pinion gear is determined based on an equation similar to equation 4-3 for each pinion gear and the pitch diameter A of the bull gear 11 calculated using equations 4-1 and 4-2. Furthermore, similar to condition 4-5, the relative positions of each pinion gear are determined so that the distances between the pinion central axes of the multiple pinion gears are the same as the multiple reference distances between the pinion central axes at the reference frequency fs.

[0159] Design method ST according to this embodiment D In a manufacturing method of a gearbox 10 having a plurality of idler gears, the above method can be used to determine the pitch diameter and rotation speed of the idler side pinion gear that meshes with each idler gear, as well as to determine the relative positions between the two pinion gears 12, 13 and the idler side pinion gear.

[0160] [Another Modification of the Second Embodiment] Design method ST for the gearbox 10 according to another modification of the second embodiment D This will be described with reference to Fig. 10. In the following description, only the differences from the design method described with reference to Fig. 6 will be described. The other design methods are the same as those in Fig. 6.

[0161] Design method ST according to this modification D In the gearbox 10 to be designed, in addition to the idler side pinion gear 16, another idler side pinion gear 17 that meshes with the idler gear 15 may be provided as shown in Fig. 11. Note that Fig. 11 shows the configuration of the bull gear 11 etc. when the target frequency ft is different from the reference frequency fs.

[0162] In step ST13 (reference setting step), in addition to the reference pitch diameters As, Bs1, and Bs3, a reference pitch diameter Bs4 of the idler-side pinion gear 17 at the reference frequency fs is set. In addition to the reference rotational speeds of the bull gear 11, pinion gear 12, and idler-side pinion gear 16, a reference rotational speed of the idler-side pinion gear 17 is set. In addition to the reference center axis distance Ls1 and the reference pinion center axis distance Ls5, a reference pinion center axis distance Ls8 (third type) between the idler-side pinion gears 16 and 17 is set as a type different from the reference pinion center axis distance shown in FIG. 9. The pitch diameter C1 of the idler gear 15 is also set.

[0163] If the target frequency ft is different from the reference frequency fs (step ST2: YES), in step ST34 (determining step), Equation 5-3, which is similar to Equation 3-3, is derived for the idler-side pinion gear 17.

[0164] (B4 / A)=(ft / fs)×(Bs4 / As) (Formula 5-3) The pitch circle diameter B4 of the idler-side pinion gear 17 is determined based on equation 5-3 and the pitch circle diameter A of the bull gear 11 calculated by equations 3-1 and 3-2. Note that equation 5-4 may be used instead of equation 5-3, provided that the center axis distance between the bull gear 11 and the idler-side pinion gear 17 is the same as the reference center axis distance therebetween at the reference frequency.

[0165] As+Bs4=A+B4 (Formula 5-4) Furthermore, similarly to condition 3-4, based on the condition that the pinion center axis distances between the pinion gear 12 and each of the idler-side pinion gears 16, 17 are the same as the reference pinion center axis distances Ls5, Ls7 at the reference frequency fs, the pitch circle diameter C2 of the idler gear 15 is determined so that the relative positions between the pinion gear 12 and each of the idler-side pinion gears 16, 17 are fixed. Note that the pitch circle diameter C2 may be the same as C1. The position of the central axis of the idler gear 15 may deviate from the position of the central axis of the idler gear 15 in the reference setting process.

[0166] Design method ST according to this modification D The following conditions are then added:

[0167] (Condition 5-1) The pinion center axis distance between the idler side pinion gears 16, 17 is the same as the reference pinion center axis distance Ls8 at the reference frequency fs.

[0168] Based on condition 5-1, the relative positions of the idler-side pinion gears 16 and 17 are determined.

[0169] Manufacturing method ST of the gearbox 10 according to this embodiment MG Even in this case, the main body size of the centrifugal compressor 1 can be prevented from changing.

[0170] Design method ST according to this modification D can also be applied to the manufacture of a gearbox 10 having three or more idler-side pinion gears that mesh with the idler gear 15. When the target frequency ft is different from the reference frequency fs, the relative positions of the idler-side pinion gears are determined so that the pinion center axis distances between the three or more idler-side pinion gears are the same as the reference pinion center axis distances at the corresponding reference frequency fs.

[0171] Design method ST according to this modification Dmay also be applied to the manufacturing method of the gearbox 10 having a plurality of pinion gears that mesh with the bull gear 11. In this case, similar to condition 3-4, the pitch circle diameter C2 of the idler gear 15 is determined so that the pinion center axis distance between each pinion gear and the idler side pinion gears 16, 17 becomes the same as the reference pinion center axis distance at the reference frequency fs.

[0172] In addition, in a manufacturing method of a gearbox 10 having two or more idler gears 15, the design method ST according to this modification is applied to the idler-side pinion gears that mesh with each idler gear. D may be applied.

[0173] As described above, by carrying out the above-described reference setting process and determination process for each of the plurality of idler gears, the plurality of pinion gears, and the plurality of idler-side pinion gears, and designing and forming the various gears, it is possible to prevent the body size of the centrifugal compressor (1) from changing even when the frequency of the power supply changes.

[0174] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the spirit of the present invention.

[0175] The manufacturing method according to the above embodiment may be applied to other rotary machines such as turbines and pumps. [Explanation of symbols]

[0176] 1. Centrifugal compressor (rotating machine) 10. Gearbox 11 Burgia 12,13 Pinion gear 15 Idler gear 16,17 Pinion gear (idler side pinion gear) 40 impeller 61 Piping 62 Motor ST DHow to design a gearbox ST MG Gearbox manufacturing method ST MC Manufacturing method of centrifugal compressor

Claims

1. A method for manufacturing a gearbox (10) for a rotary machine (1) for transmitting power of a motor, the gearbox (10) comprising a bull gear (11) connected to an input shaft of the motor and a pinion gear (12) meshing with the bull gear (11), the method comprising: a reference setting step of setting a reference center axis distance (Ls1) that is the distance between the center axis of the bull gear (11) and the center axis of the pinion gear (12) and a reference rotation speed that is the rotation speed of the pinion gear (12), both of which are defined when the frequency of the AC power supplied to the motor is a predetermined frequency; a determining step of determining pitch circle diameters (A, B) of the bull gear (11) and the pinion gear (12) so that, when the frequency of the AC power supplied to the motor is different from the predetermined frequency, a center axis distance between the center axis of the bull gear (11) and the center axis of the pinion gear (12) is the same as the reference center axis distance (Ls1) and so that the rotation speed of the pinion gear (12) is the same as the reference rotation speed; Using the design results determined through a design process including forming the bull gear (11); forming the pinion gear (12); To execute A method for manufacturing a gearbox (10).

2. The gearbox (10) for the rotary machine (1) further comprises another pinion gear (13) that meshes with the bull gear (11); In the reference setting step, a reference center axis distance (Ls2) which is the distance between the center axis of the bull gear (11) and the center axis of the other pinion gear (13), a reference pinion center axis distance (Ls3) which is the distance between the center axis of the pinion gear (12) and the center axis of the other pinion gear (13), and a reference rotation speed which is the rotation speed of the other pinion gear (13) are further set, which are defined when the frequency of the AC power supplied to the motor is a predetermined frequency, In the determination step, when the frequency of the AC power supplied to the motor is different from the predetermined frequency, a pitch circle diameter (B2) of the other pinion gear (13) is further determined so that a center axis distance between the center axis of the bull gear (11) and the center axis of the other pinion gear (13) is the same as the reference center axis distance (Ls2) and the rotation speed of the other pinion gear (13) is the same as the reference rotation speed; and 2. The method for manufacturing a gearbox (10) according to claim 1, further comprising determining a relative position between each of the pinion gears (12, 13) so that a pinion center axis distance, which is a distance between the center axis of the pinion gear (12) and the center axis of the other pinion gear (13), is the same as the reference pinion center axis distance (Ls3).

3. A method for manufacturing a gearbox (10) for a rotary machine (1) for transmitting power of a motor, the gearbox (10) comprising: a bull gear (11) connected to an input shaft of a motor; a pinion gear (12) meshing with the bull gear (11); an idler gear (15) meshing with the bull gear (11); and an idler-side pinion gear (16) meshing with the idler gear (15), the method comprising the steps of: a reference setting step of setting a reference center axis distance (Ls1) that is the distance between the center axis of the bull gear (11) and the center axis of the pinion gear (12), a reference pinion center axis distance (Ls5) that is the distance between the center axis of the pinion gear (12) and the center axis of the idler side pinion gear (16), a reference rotation speed that is the rotation speed of the pinion gear (12), and another reference rotation speed that is the rotation speed of the idler side pinion gear (16), all of which are defined when the frequency of the AC power supplied to the motor is a predetermined frequency; a determining step of determining pitch circle diameters (A, B1, B3) of the bull gear (11), the pinion gear (12), and the idler-side pinion gear (16) so that, when the frequency of the AC power supplied to the motor is different from the predetermined frequency, a center-to-center distance between the center axis of the bull gear (11) and the center axis of the pinion gear (12) is the same as the reference center-to-center distance (Ls1), the rotation speed of the pinion gear (12) is the same as the reference rotation speed, and the rotation speed of the idler-side pinion gear (16) is the same as the other reference rotation speed, and determining a pitch circle diameter (C2) of the idler gear (15) so that a pinion center-to-center distance between the center axis of the pinion gear (12) and the center axis of the idler-side pinion gear (16) is the same as the reference pinion center-to-center distance (Ls5); Using the design results determined through a design process including forming the bull gear (11); forming the pinion gear (12); forming the idler gear (15); forming the idler-side pinion gear (16); To execute A method for manufacturing a gearbox (10).

4. The gearbox (10) for the rotary machine (1) further comprises another pinion gear (13) that meshes with the bull gear (11); In the reference setting step, a reference center axis distance (Ls2) which is the distance between the center axis of the bull gear (11) and the center axis of the other pinion gear (13), a reference pinion center axis distance (Ls3) which is the distance between the center axis of the pinion gear (12) and the center axis of the other pinion gear (13), a reference pinion center axis distance (Ls6) which is the distance between the center axis of the idler side pinion gear (16) and the center axis of the other pinion gear (13), and a reference rotation speed which is the rotation speed of the other pinion gear (13) are further set, which are defined when the frequency of the AC power supplied to the motor is a predetermined frequency, In the determination step, when the frequency of the AC power supplied to the motor is different from the predetermined frequency, a pitch circle diameter (B2) of the pinion gear (13) is further determined so that a center axis distance between the center axis of the bull gear (11) and the center axis of the other pinion gear (13) is the same as the reference center axis distance (Ls2) and the rotation speed of the pinion gear (13) is the same as the reference rotation speed; and further determining the relative positions of the pinion gears (12, 13) so that a pinion center axis distance, which is a distance between the center axis of the pinion gear (12) and the center axis of the other pinion gear (13), is equal to the reference pinion center axis distance (Ls3); The pitch circle diameter (C2) of the idler gear (15) is determined so that a pinion center axis distance, which is a distance between the center axis of the pinion gear (12) and the center axis of the idler side pinion gear (16), is the same as the reference pinion center axis distance (Ls5), and so that a pinion center axis distance, which is a distance between the center axis of the other pinion gear (13) and the center axis of the idler side pinion gear (16), is the same as the reference pinion center axis distance (Ls6). A method for manufacturing a gearbox (10) according to claim 3.

5. Further provided is another idler-side pinion gear (17) that meshes with the idler gear (15), In the reference setting step, a reference pinion center axis distance (Ls7) which is the distance between the center axis of the pinion gear (12) and the center axis of the other idler side pinion gear (17), another reference rotation speed which is the rotation speed of the other idler side pinion gear (17), and a reference pinion center axis distance (Ls8) which is the distance between the center axis of the idler side pinion gear (16) and the center axis of the other idler side pinion gear (17) are further set, which are defined when the frequency of the AC power supplied to the motor is a predetermined frequency; In the determination step, when the frequency of the AC power supplied to the motor is different from the predetermined frequency, a pitch circle diameter (B4) of the other idler side pinion gear (17) is determined so that the rotation speed of the other idler side pinion gear (17) becomes the same as the other reference rotation speed; determining a pitch circle diameter (C2) of the idler gear (15) so that the pinion center axis distance, which is the distance between the center axis of the pinion gear (12) and the center axis of the idler-side pinion gear (16), is the same as the reference pinion center axis distance (Ls5), and so that the pinion center axis distance, which is the distance between the center axis of the pinion gear (12) and the center axis of another idler-side pinion gear (17), is the same as the reference pinion center axis distance (Ls7); 5. The method for manufacturing a gearbox (10) according to claim 3 or 4, further comprising determining a relative position of each of the idler side pinion gears (16, 17) so that a pinion center axis distance, which is a distance between the center axis of the idler side pinion gear (16) and the center axis of the other idler side pinion gear (17), is the same as the reference pinion center axis distance (Ls8).

6. A method for manufacturing a rotary machine (1), comprising the step of manufacturing a gearbox (10) by the manufacturing method according to any one of claims 1 to 3.

7. The method for manufacturing a rotary machine (1) according to claim 6, wherein the rotary machine (1) is a centrifugal compressor.

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