Turbo compressor

Abstract

To provide a turbo compressor for having a tension bolt which easily follows up a temperature change of a member arranged around the tension bolt.SOLUTION: The turbo compressor includes an impeller 10 having a through-hole 10a, a rotary shaft 15b, and a tension bolt 17, the tension bolt 17 having an intermediate part 17a between a first male screw part 17b and a second male screw part 17c in the longitudinal direction, the intermediate part 17a being arranged in the through-hole 10a of the impeller 10, the intermediate part 17a having a radiation portion laminated on the outer periphery side of a body part inside in the shaft diameter direction, in at least part in the longitudinal direction, the radiation portion being opposed to the inner peripheral face of the impeller 10, around the through-hole 10a, via a gap G and formed of a material having higher emissivity than the body part.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a turbo compressor.

Background Art

[0002] Conventionally, turbo-type compressors are known. In Patent Document 1, a turbo compressor is disclosed that includes tension bolts that sandwich and support an impeller against a rotating shaft at a predetermined pressure. The tension bolts are formed with male threads at both ends of a high-strength steel bar. In the sandwiching support of the impeller against the rotating shaft using the tension bolts, first, the tension bolts are passed through the through holes of the impeller, and the male thread on one end side is screwed into the female thread provided at the tip of the rotating shaft. Next, with a predetermined tensile force applied to the tension bolts, a nut is screwed onto the other male thread protruding from the impeller. By sandwiching and supporting the impeller against the rotating shaft using the tension bolts in this way, the impeller is sandwiched between the rotating shaft and the nut by the reaction force (axial force) of the tensile force generated in the tension bolts.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, components such as the impeller in a turbo compressor expand and contract depending on the ambient temperature. Therefore, it is preferable that the tension bolts also expand and contract with high responsiveness to the expansion and contraction of other components.

[0005] However, in turbo compressors, heat exchange in the tension bolts is limited to the contact points with other components, resulting in slower temperature changes in the tension bolts compared to other components. Therefore, there is a concern that the tension bolts may loosen or overtighten during turbo compressor operation due to the slower temperature changes compared to surrounding components. This problem becomes particularly pronounced when handling high-temperature gases.

[0006] This invention has been made in view of the above problems, and aims to make it easier for a tension bolt to follow temperature changes in a member arranged around the tension bolt. [Means for solving the problem]

[0007] A turbo compressor according to one aspect of the present invention comprises a rotating member, a rotating shaft, and a tension bolt. The rotating member includes an impeller and has a through hole formed at its center of rotation. The rotating shaft is a shaft member for rotating the rotating member and has a female threaded portion formed at its tip. The tension bolt has its longitudinal middle portion located within the through hole, a first male threaded portion protruding from one opening of the through hole is screwed with a nut outside the impeller, and a second male threaded portion protruding from the opening opposite to the first opening is screwed with the female threaded portion.

[0008] The tension bolt of the turbo compressor according to this embodiment has a main body and a radiating portion in the intermediate section. The radiating portion is a part that is stacked on the outer circumference of the main body in at least a part of the longitudinal direction of the intermediate section. In the turbo compressor according to this embodiment, the radiating portion is connected to the portion of the rotating member surrounding the radiating portion through a gap. In a non-contact state They are positioned opposite each other and are made of a material with a higher emissivity than the main body. The dimension of the gap is 5% to 50% of the diameter of the tension bolt.

[0009] In the turbo compressor according to the above embodiment, since a radiating portion is stacked on the outer circumference of at least a part of the main body in the middle portion of the tension bolt, the surface emissivity in that portion can be made higher than that of the main body. Therefore, in the turbo compressor according to this embodiment, radiant heat transfer can be effectively utilized, and the tension bolt can easily follow the temperature changes of the rotating member (member arranged around the tension bolt). Thus, the occurrence of loosening or overtightening of the tension bolt can be suppressed during the operation of the turbo compressor. Furthermore, in the turbo compressor according to the above embodiment, even when the gap between the rotating member and the tension bolt is in the range of 5% to 50% of the diameter of the tension bolt, the presence of a radiating section allows for effective utilization of radiant heat transfer, enabling the compressor to respond to temperature changes in the rotating member with high responsiveness.

[0010] In the turbo compressor according to the above embodiment, the radiating portion may be a coating layer formed on the outer periphery of the main body by ceramic thermal spraying.

[0011] In the turbo compressor according to the above embodiment, the radiating section is composed of a coating layer formed by ceramic thermal spraying, which allows for excellent durability and heat resistance of the radiating section.

[0012] In the turbo compressor according to the above embodiment, the coating layer may consist of a ceramic coating containing at least one of aluminachromia and alumina-titania.

[0013] In the turbo compressor according to the above embodiment, a coating layer made of a ceramic coating containing the above-mentioned materials is employed, making it easy to spray and resulting in a dense coating. Specifically, a ceramic coating containing at least one of aluminachromia and alumina-titania exhibits better wear resistance than a coating of alumina or titania alone.

[0016] In the turbo compressor according to the above embodiment, the rotating member may have a rotating member body which is the main body of the rotating member, and another radiating portion. The other radiating portion may be a portion laminated on at least a part of the surface of the rotating member body that faces the intermediate portion of the tension bolt. Furthermore, in the turbo compressor according to this embodiment, the other radiating portion may be made of a material with a higher emissivity than the rotating member body.

[0017] In the turbo compressor according to the above embodiment, since other radiating elements are provided on at least a portion of the part of the rotating member that faces the intermediate portion of the tension bolt, heat can be transferred to the tension bolt more efficiently by radiation. Therefore, it is even more advantageous in suppressing loosening or overtightening of the tension bolt during the operation of the turbo compressor.

[0018] In the turbo compressor according to the above embodiment, the radiating portion of the tension bolt may be provided in a part of the longitudinal direction of the intermediate portion. Furthermore, the tension bolt may have a contact portion that contacts the rotating member in a portion of the intermediate portion other than the portion where the radiating portion is provided.

[0019] In the turbo compressor according to the above embodiment, since the tension bolts have contact portions, axial misalignment of the tension bolts with respect to the rotating members can be suppressed. Therefore, wear of the radiating portion can be suppressed even with the rotation of the rotating shaft and the impeller.

[0020] The tension bolt of the turbo compressor according to the above embodiment may have another radiating portion at the contact portion. The other radiating portion may be provided in the portion that contacts the rotating member and may be made of a material with a higher emissivity than the main body portion.

[0021] In the turbo compressor according to the above embodiment, since another radiating portion is formed at the contact portion of the tension bolt with the rotating member, wear can be suppressed even if sliding occurs at the contact portion.

Advantages of the Invention

[0022] In the turbo compressor according to each of the above aspects, the tension bolt easily follows the temperature change of the members arranged around the tension bolt.

Brief Description of the Drawings

[0023] [Figure 1] It is a cross-sectional view showing a partial configuration of the turbo compressor according to the first embodiment of the present invention. [Figure 2] It is a cross-sectional view showing the tension bolt and its peripheral members in the turbo compressor. [Figure 3] It is a notch view showing the configuration of the middle part of the tension bolt. [Figure 4] It is a graph showing the simulation results of the temperature change of the tension bolt. [Figure 5] It is a graph showing the simulation results of the stress change acting on the tension bolt. [Figure 6] It is a cross-sectional view showing a partial configuration of the turbo compressor according to the second embodiment of the present invention. [Figure 7] It is a cross-sectional view showing a partial configuration of the turbo compressor according to the third embodiment of the present invention. [Figure 8] It is a cross-sectional view showing a partial configuration of the turbo compressor according to the fourth embodiment of the present invention. [Figure 9] It is a cross-sectional view showing a partial configuration of the turbo compressor according to the fifth embodiment of the present invention.

Modes for Carrying Out the Invention

[0024] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below are illustrative of the present invention, and the present invention is not limited to the following embodiments except for its essential configuration.

[0025] [First Embodiment] 1. Structure of Turbo Compressor 1 The structure of the turbo compressor 1 according to the first embodiment of the present invention will be described with reference to Figure 1. Note that Figure 1 shows only a portion of the components of the turbo compressor 1.

[0026] As shown in Figure 1, the turbo compressor 1 comprises a rotating member, a casing 11, and a casing cover 12. The turbo compressor 1 also comprises a gear case 13, a bull gear 16, and a pinion gear 15.

[0027] The gear case 13 is a case member having a housing space 13a for housing the bull gear 16 and the pinion gear 15. The casing cover 12 is fastened to the gear case 13 by fastening members (not shown in the figure).

[0028] The gear case 13 has a case hole 13b that connects the housing space 13a to the outside. The casing cover 12 is provided so that the centerlines of the case hole 13b of the gear case 13 coincide, and has a cover hole 12a that penetrates in the thickness direction. The gear case 13 and the casing cover 12 are fastened together so that the case hole 13b of the gear case 13 and the cover hole 12a of the casing cover 12 are in communication with each other.

[0029] The casing cover 12 has the casing 11 attached to the side opposite to the side attached to the gear case 13. The casing 11 is also attached to the casing cover 12 using fastening members, which are not shown in the figures. The space 1a formed by the casing cover 12 and the casing 11 houses the impeller 10.

[0030] The rotating member is a member that rotates on a rotating shaft 15b, which will be described later, and in this embodiment, it is configured as an impeller 10.

[0031] In the turbo compressor 1, during operation, kinetic energy is imparted to the gas by the rotation of the impeller 10 in the space 1a formed by the casing cover 12 and the casing 11. Then, in the portion of space 1a radially outside the impeller 10, the gas to which kinetic energy has been imparted by the rotation of the impeller 10 is decelerated and pressurized. During operation of the turbo compressor 1, temperature changes occur in the impeller 10, the casing 11 and casing cover 12, etc., which are affected by the compressed gas. The impeller 10, casing 11 and casing cover 12, etc., expand and contract in accordance with the temperature changes.

[0032] A motor or turbine (not shown) is connected to the pull gear 16 housed in the storage space 13a of the gear case 13. The pull gear 16 rotates by receiving rotational driving force from a rotational drive source such as a motor.

[0033] The pinion gear 15 has a gear body 15a that meshes with the bull gear 16, and a rod-shaped rotating shaft 15b formed integrally with the gear body 15a. The rotating shaft 15b of the pinion gear 15 is positioned so that its end face faces the space 1a side, passing through the case hole 13b of the gear case 13 and the cover hole 12a of the casing cover 12. The rotating shaft 15b is rotatably supported by a bearing 14 attached to the inner circumference of the gear case 13 that forms the case hole 13b.

[0034] The impeller 10 is attached to the rotating shaft 15b using tension bolts 17 and nuts 18.

[0035] 2. Mounting structure of the impeller 10 to the rotating shaft 15b The mounting structure of the impeller 10 to the rotating shaft 15b will be explained using Figure 2. Figure 2 is an enlarged cross-sectional view showing the mounting portion of the impeller 10 to the rotating shaft 15b and the surrounding portion.

[0036] As shown in Figure 2, the rotating shaft 15b has a female threaded portion 15c formed at the end to which the impeller 10 is attached. The female threaded portion 15c is formed at the rotation center of the rotating shaft 15b.

[0037] Although not shown in Figure 1, a cylindrical seal portion 19 with a labyrinth structure is positioned between the outer circumferential surface of the rotating shaft 15b and the inner circumferential surface surrounding the cover hole 12a in the casing cover 12. The seal portion 19 suppresses gas leakage from the space 1a in which the impeller 10 is housed to the housing space 13a of the gear case 13.

[0038] The impeller 10 has a through hole 10a formed at its center of rotation. In other words, in this embodiment, the through hole 10a of the impeller 10 is the "through hole of the rotating member". The through hole 10a of the impeller 10 and the female threaded portion 15c of the rotating shaft 15b are positioned so that their respective centerlines coincide.

[0039] The tension bolts 17 for attaching the impeller 10 to the rotating shaft 15b are positioned to pass through the through-holes 10a of the impeller 10.

[0040] The tension bolt 17 has an integrally formed intermediate portion 17a, a first male threaded portion 17b, and a second male threaded portion 17c. The intermediate portion 17a is located within the through hole 10a, as indicated by arrow A in Figure 2. The first male threaded portion 17b protrudes from the opening in the through hole 10a opposite to the side in which the rotating shaft 15b is attached. A nut 18 is screwed onto the first male threaded portion 17b. The second male threaded portion 17c protrudes from the opening in the through hole 10a on the side in which the rotating shaft 15b is attached. The second male threaded portion 17c is screwed onto the female threaded portion 17c of the rotating shaft 15b.

[0041] In the state where the rotating shaft 15b and the impeller 10 are connected by the tension bolt 17 and nut 18, tensile stress is applied to the tension bolt 17 in the longitudinal direction. This makes the connection between the rotating shaft 15b and the impeller 10 strong.

[0042] As shown by the arrow A in Figure 2, the intermediate portion 17a of the tension bolt 17 is formed to have an outer diameter D17. In contrast, the through hole 10a of the impeller 10 is formed to have a larger diameter than the outer diameter D17 of the intermediate portion 17a, so that there is a gap G with respect to the outer circumferential surface of the tension bolt 17. In other words, in this embodiment, the inner circumferential surface constituting the through hole 10a of the impeller 10 surrounds the intermediate portion 17a of the tension bolt 17 with a gap G. That is, in this embodiment, the rotating member configured as the impeller 10 surrounds the periphery of the intermediate portion 17a of the tension bolt 17.

[0043] In this embodiment, the dimension of the gap G is set to be 5% or more and 50% or less of the diameter of the tension bolt 17 (outer diameter D17 of the intermediate portion 17a).

[0044] In this embodiment, a tension bolt 17 with an upper limit of approximately 350°C in its operating temperature range is used.

[0045] 3. Structure of the intermediate portion 17a in the tension bolt 17 The structure of the intermediate portion 17a of the tension bolt 17 will be explained using Figure 3. In Figure 3, a portion of the longitudinal direction of the intermediate portion 17a of the tension bolt 17 is shown cut out.

[0046] As shown in Figure 3, the intermediate portion 17a of the tension bolt 17 has a rod-shaped main body portion 17d having a circular cross-section, and a radiating portion 17e that is laminated on the outer peripheral portion (layer outer peripheral surface) 17f of the main body portion 17d in at least a portion of its longitudinal direction. In this embodiment, the radiating portion 17e is laminated over the entire longitudinal region of the main body portion 17d, extending around its entire circumference. Thus, over the entire longitudinal region of the intermediate portion 17a, the outer peripheral surface of the radiating portion 17e constitutes the outer peripheral surface 17g of the intermediate portion 17a. In the intermediate portion 17a, the region in which the radiating portion 17e is laminated relative to the main body portion 17d may be a portion in the longitudinal direction or a portion in the circumferential direction.

[0047] In this embodiment, the main body portion 17d is formed using titanium alloy, stainless steel alloy, heat-resistant steel, nickel-chromium-molybdenum steel, chromium-molybdenum steel, or the like.

[0048] The radiating section 17e is made of a material with a higher emissivity than the main body section 17d. Generally, by using a material with an emissivity of 0.8 or higher as the radiating section 17e, it can be said that its emissivity is higher than that of the main body section 17d.

[0049] Furthermore, "a material with higher emissivity than the main body 17d" means that, when a comparative product is prepared that is made of the same material as the main body 17d but does not have a laminated radiating portion 17e, the radiating portion 17e has a higher emissivity than the comparative product. Specifically, "a material with higher emissivity than the main body 17d" means that, when comparing the comparative product and the tension bolt 17 of this embodiment, with both surfaces unoxidized and having the same surface roughness, the radiating portion 17e has a higher emissivity than the comparative product.

[0050] In this embodiment, the radiating portion 17e is a coating layer formed by ceramic thermal spraying on the outer peripheral surface (layer outer peripheral surface) 17f of the main body portion 17d. However, the radiating portion 17d is not limited to a coating layer formed by ceramic thermal spraying. For example, it may be a coating film formed by applying heat-resistant paint.

[0051] As a specific example of the coating layer constituting the radiating portion 17e, a layer consisting of a ceramic coating containing at least one of aluminachromia and alumina-titania can be employed.

[0052] 4. Effects In the turbo compressor 1 according to this embodiment, in the intermediate portion 17a of the tension bolt 17, a radiating portion 17e is laminated on the outer peripheral surface 17f of the main body portion 17d in at least a portion of the longitudinal direction. Therefore, in the turbo compressor 1, the emissivity of the surface (outer peripheral surface 17g) of the portion of the tension bolt 17 in which the radiating portion 17e is laminated can be made higher than that of the main body portion 17d. As a result, the turbo compressor 1 can effectively utilize radiant heat transfer and make it easier for the tension bolt 17 to follow the temperature changes of the impeller 10. Thus, it is possible to suppress the occurrence of loosening or overtightening of the tension bolt 17 during the operation of the turbo compressor 1.

[0053] Furthermore, in the turbo compressor 1 according to this embodiment, the radiating portion 17e of the tension bolt 17 is composed of a coating layer formed by ceramic thermal spraying, which makes the radiating portion 17e highly durable and heat resistant.

[0054] Furthermore, the turbo compressor 1 according to this embodiment employs a coating layer made of a ceramic coating containing at least one of aluminachromia and alumina-titania, making it easy to spray and resulting in a dense coating. Specifically, the ceramic coating containing at least one of aluminachromia and alumina-titania has excellent film-forming properties and exhibits better wear resistance than coatings made of alumina or titania alone.

[0055] Furthermore, in the turbo compressor 1 according to this embodiment, the dimension of the gap G between the impeller 10 and the tension bolt 17 is set to a range of 5% to 50% of the outer diameter D17 of the tension bolt 17. In the turbo compressor 1, even in such a case, a radiating portion 17e is provided in the intermediate portion 17a of the tension bolt 17, so radiant heat transfer can be effectively utilized. Therefore, the turbo compressor 1 can make the tension bolt 17 follow the temperature change of the impeller 10 with high responsiveness.

[0056] 5. Confirmation of effectiveness The simulation results obtained to confirm the above effects will be explained using Figures 4 and 5. Figure 4 is a graph showing the temperature change of the tension bolts over time during turbo compressor startup, and Figure 5 is a graph showing the stress change acting on the tension bolts over time.

[0057] First, in this simulation, the examples and comparative examples were set up as follows.

[0058] <Examples> As an example, similar to the first embodiment described above, a radiating portion 17e was provided in the intermediate portion 17a of the tension bolt 17. Specifically, in the tension bolt 17 of the example, the intermediate portion 17a was assumed to be made of SUS630 material with an aluminachromia surface coating, and the emissivity was set to 0.8 (emissivity of aluminachromia).

[0059] <Comparative Example> As a comparative example, the intermediate portion 17a was not provided with a radiating portion 17e, and assuming an uncoated SUS630 material, the surface emissivity was set to 0.2 (emissivity of machined SUS630 material). The comparative example was identical to the example in all other conditions except for the absence of a radiating portion in the intermediate portion of the tension bolt.

[0060] In this verification, we took one operating example of each turbo compressor in the above examples and comparative examples when it increased from a standstill to its rated rotational speed, and calculated the temperature of the tension bolts and the stress acting on the tension bolts for each. For the calculations, it was assumed that the temperature of each part of the compressor was uniform (12°C) while it was stopped.

[0061] <result> First, as shown in Figure 4, the temperature of the tension bolts in the embodiment and comparative example increases as time passes from the start of the turbo compressor. That is, in both the embodiment and comparative example, the temperature of the tension bolts gradually approaches the temperature of the inner circumferential surface constituting the through hole 10a in the impeller 10 (dotted line in Figure 4) as time passes.

[0062] The tension bolt 17 in the embodiment, shown by the solid line, shows a greater degree of temperature rise compared to the comparative example, shown by the dashed line. Specifically, after 500 seconds, the temperature of the tension bolt in the comparative example was approximately 19% of the temperature of the inner surface of the impeller, while the temperature of the tension bolt 17 in the embodiment was approximately 21% of the temperature of the inner surface of the impeller.

[0063] Furthermore, at the 1000-second mark, the temperature of the tension bolt in the comparative example was approximately 43% of the temperature of the inner surface of the impeller, while the temperature of the tension bolt 17 in the example was approximately 50% of the temperature of the inner surface of the impeller.

[0064] Furthermore, at 1500 seconds, the temperature of the tension bolt in the comparative example was approximately 65% ​​of the temperature of the inner surface of the impeller, while the temperature of the tension bolt 17 in the example was 74% of the temperature of the inner surface of the impeller.

[0065] Next, as shown in Figure 5, the maximum stress acts on the tension bolt 17 of the embodiment and the tension bolt of the comparative example at 650 to 700 seconds. The maximum stress acting on the tension bolt 17 of the embodiment was approximately 3% lower than the maximum stress acting on the tension bolt of the comparative example.

[0066] When examining the stress acting on the tension bolts over time, as described above, the stress reached its maximum value at 650-700 seconds, and then gradually decreased in both the example and the comparative example. The degree of decrease from the maximum stress value was greater for tension bolt 17 in the example than for tension bolt in the comparative example. Specifically, at 1000 seconds, the stress value in the comparative example decreased to about 92% of the maximum stress value, while the stress value in the example decreased to about 89% of the maximum stress value.

[0067] Furthermore, at 1500 seconds, the stress value in the comparative example decreased to approximately 76% of the maximum stress value, while in the example, the stress value decreased to approximately 71% of the maximum stress value.

[0068] <Consideration> In the embodiment, the tension bolt 17 employs a configuration that includes a radiating portion 17e in the intermediate portion 17a. As a result, the temperature of the tension bolt 17 follows the temperature change of the inner circumferential surface of the impeller (the inner circumferential surface constituting the through hole 10a in the impeller 10) better than that of the comparative example. Therefore, it was confirmed that the stress acting on the tension bolt 17 in the embodiment decreased faster than that of the comparative example.

[0069] From the above, it was confirmed that by providing a radiating portion 17e in the intermediate portion 17a of the tension bolt 17, the tension bolt 17 can be made to follow the temperature changes of the impeller 10 with high responsiveness.

[0070] [Second Embodiment] A turbo compressor 1 according to a second embodiment of the present invention will be described with reference to Figure 6. Note that in Figure 6, only the tension bolt 17 and its surrounding area are shown. In this embodiment, the turbo compressor 1 employs the same configuration as the first embodiment described above, except for the parts that are not shown in Figure 6.

[0071] First, in the turbo compressor 1 according to this embodiment, the impeller 10 is not directly attached to the rotating shaft 15b, but rather attached to the rotating shaft 15b with an intermediate member 20 in between. That is, the intermediate member 20 is interposed in the transmission path of rotational driving force from the rotating shaft 15b to the impeller 10. This is the difference from the first embodiment described above.

[0072] As shown in Figure 6, the intermediate member 20 is positioned within the cover hole 12a of the casing cover 12. Therefore, in the turbo compressor 1 according to this embodiment, the seal portion 19 is positioned between the outer circumferential surface of the intermediate member 20 and the inner circumferential surface of the casing cover 12 that surrounds the cover hole 12a.

[0073] In this embodiment, the intermediate member 20 is formed using a metal material with higher heat resistance than the pinion gear 15 (for example, austenitic stainless steel, precipitation-hardening stainless steel, or titanium).

[0074] The intermediate member 20 has a through hole 20a that penetrates the rotation center in the axial direction. The through hole 20a communicates with the female thread portion 15c on the rotation shaft 15b side and with the through hole 10a on the impeller 10 side.

[0075] In this embodiment, the intermediate portion 17a of the tension bolt 17 is surrounded by the impeller 10 and the intermediate member 20 with a gap G between them. That is, the intermediate portion 17a of the tension bolt 17 is positioned extending from the impeller through hole 10a to the through hole 20a of the intermediate member 20.

[0076] In this embodiment, the impeller 10 and the intermediate member 20 are included in the "rotating member" that rotates on the rotation shaft 15b. The through hole 10a of the impeller 10 and the through hole 20a of the intermediate member 20 are the "through holes of the rotating member".

[0077] A nut 18 is screwed onto the first male threaded portion 17b of the tension bolt 17. The second male threaded portion 17c of the tension bolt 17 is screwed onto the female threaded portion 15c of the rotating shaft 15b. As a result, the intermediate member 20 is sandwiched between the rotating shaft 15b and the impeller 10.

[0078] As shown in part B of Figure 6, the intermediate portion 17a of the tension bolt 17 has a radiating portion 17e laminated on the outer circumference of the main body portion 17d in at least a portion of its longitudinal direction. The radiating portion 17e is made of the same material as in the first embodiment. Also, the radiating portion 17e is a coating layer formed by ceramic thermal spraying, similar to the first embodiment.

[0079] The radiating portion 17e of the tension bolt 17 faces the impeller 10 and the intermediate member 20 with a gap G in between. The ratio of the gap G to the outer diameter D17 (see Figure 2) of the intermediate portion 17a of the tension bolt 17 is 5% or more and 50% or less, as in the first embodiment described above.

[0080] In the turbo compressor 1 according to this embodiment, the radiating portion 17e of the tension bolt 17 is formed in at least a portion of the intermediate portion 17a that is located within the through-hole 10a of the impeller 10 and the through-hole 20a of the intermediate member 20. That is, in this embodiment, the radiating portion 17e may be provided over the entire longitudinal area of ​​the intermediate portion 17a that is located within the through-hole 10a of the impeller 10 and the through-hole 20a of the intermediate member 20, or it may be provided only in a portion of the longitudinal area. For example, the radiating portion 17e may be provided only in the portion located within the through-hole 20a of the intermediate member 20, or it may be provided only in the portion located within the through-hole 10a of the impeller 10. Furthermore, the radiating portion 17e may be provided in a portion of the portion located within the through-hole 10a of the impeller 10 and a portion of the portion located within the through-hole 20a of the intermediate member 20.

[0081] The turbo compressor 1 according to this embodiment has the above-described configuration and can obtain the same effects as the first embodiment. That is, in the turbo compressor 1 according to this embodiment as well, the intermediate portion 17a of the tension bolt 17 has a radiating portion 17e in at least a part of the portion located within the through hole 10a of the impeller 10 and the through hole 20a of the intermediate member 20. Therefore, in this embodiment as well, the formation of the radiating portion 17e in the tension bolt 17 makes it possible to effectively utilize radiant heat transfer from at least one of the impeller 10 and the intermediate member 20. Thus, the tension bolt 17 can be made more responsive to temperature changes in the at least one of the members, and the occurrence of loosening or overtightening of the tension bolt 17 during operation of the turbo compressor 1 can be suppressed. Furthermore, if the radiating portion 17e is formed over the entire area of ​​the portion located within the through hole 10a of the impeller 10 and the through hole 20a of the intermediate member 20, radiant heat transfer can be utilized more effectively.

[0082] [Third Embodiment] A turbo compressor 1 according to a third embodiment of the present invention will be described with reference to Figure 7. In Figure 7, only the tension bolt 17 and its surrounding area are shown. The turbo compressor 1 according to this embodiment employs the same configuration as the second embodiment described above, except for the parts that are not shown in Figure 7.

[0083] First, the turbo compressor 1 according to this embodiment differs from the second embodiment in that a contact portion 17h is provided on the intermediate portion 17a of the tension bolt 17. Furthermore, the tension bolt 17 in this embodiment also has a radiating portion 17e in the portion located within the through hole 10a of the impeller 10. However, as with the second embodiment, the radiating portion 17e only needs to be provided in a portion of the portion located within the through hole 10a of the impeller 10 and the through hole 20a of the intermediate member 20.

[0084] As shown in Figure 7, the tension bolt 17 has a contact portion 17h that is larger in diameter than other portions in a part of the portion located within the through hole 20a of the intermediate member 20. As shown in portion C of Figure 7, the outer surface of the contact portion 17h of the tension bolt 17 contacts the inner surface of the intermediate member 20 that surrounds the through hole 20a.

[0085] Furthermore, in the contact portion 17h of the tension bolt 17, the radiating portion 17e is not formed on the surface layer, and the main body portion 17d is exposed on the outer circumferential surface. That is, in the turbo compressor 1 according to this embodiment, the radiating portion 17e of the tension bolt 17 is formed only on a part of the longitudinal direction of the intermediate portion 17a, and the contact portion 17h is formed in the portion where the radiating portion 17e is not provided.

[0086] In this embodiment, a single contact portion 17h is provided in a part of the intermediate portion 17a of the tension bolt 17 that is located within the through hole 20a of the intermediate member 20. However, multiple contact portions 17h may be provided in the intermediate portion 17a, or they may be provided in a part located within the through hole 10a of the impeller 10.

[0087] The turbo compressor 1 according to this embodiment has the above-described configuration and can obtain the same effects as the second embodiment. That is, in the turbo compressor 1 according to this embodiment as well, the radiating portion 17e is stacked on the outer circumference of the main body portion 17d, except for the portion of the intermediate portion 17a of the tension bolt 17 where the contact portion 17h is provided. Therefore, in this embodiment as well, the radiant heat transfer from the intermediate member 20 can be effectively utilized in the portion of the tension bolt 17 where the radiating portion 17e is formed. Thus, it is possible to suppress the occurrence of loosening or overtightening of the tension bolt 17 during the operation of the turbo compressor 1.

[0088] Furthermore, in the turbo compressor 1 according to this embodiment, a contact portion 17h is provided on a part of the intermediate portion 17a of the tension bolt 17, so that axial misalignment of the tension bolt 17 with respect to the intermediate member 20 can be suppressed. Therefore, in the turbo compressor 1 according to this embodiment, wear of the radiating portion 17e provided on the tension bolt 17 can be suppressed even by the rotation of the rotating shaft 15b and the impeller 10.

[0089] [Fourth Embodiment] A turbo compressor 1 according to the fourth embodiment of the present invention will be described with reference to Figure 8. In Figure 8, only the tension bolt 17 and its surrounding area are shown. The turbo compressor 1 according to this embodiment employs the same configuration as the third embodiment described above, except for the parts that are not shown in Figure 8.

[0090] First, in the turbo compressor 1 according to this embodiment, the structure of the contact portion 17h of the tension bolt 17 differs from that of the third embodiment described above. The other structural aspects are the same as those of the third embodiment described above.

[0091] As shown in Figure 8, in the turbo compressor 1 according to this embodiment, a contact radiation portion 17i is formed on the surface portion of the contact portion 17h of the tension bolt 17. In the turbo compressor 1 according to this embodiment, the contact radiation portion 17i is formed continuously with the radiation portions 17e formed on the front and rear sides in the longitudinal direction of the tension bolt 17.

[0092] In this embodiment, the portion of the radiating portion 17e and 17i formed on the surface of the tension bolt 17 that is not the contact portion 17i is the "radiating portion" (radiating portion 17e), and the portion of the surface of the contact portion 17i is the "other radiating portion" (contact radiating portion 17i). However, the radiating portion 17e and the contact radiating portion 17i do not necessarily have to be formed continuously and may be formed discontinuously with respect to each other.

[0093] In this embodiment, the contact radiation section 17i is formed using the same material and the same forming method (ceramic thermal spraying) as the radiation section 17e. Furthermore, in this embodiment, the contact radiation section 17i and the radiation section 17e are formed to be continuous.

[0094] The turbo compressor 1 according to this embodiment has the above-described configuration and can obtain the same effects as the third embodiment described above.

[0095] Furthermore, in the turbo compressor 1 according to this embodiment, a contact radiant portion 17i made of the same material as the radiant portion 17e is also provided on the surface layer of the contact portion 17h, so that heat can be received from the intermediate member 20 from this portion as well. Ensuring that the contact radiant portion 17i also functions as a radiant portion provides an even greater advantage in making the tension bolt 17 follow the temperature changes of the intermediate member 20 and other components when the turbo compressor 1 is in operation.

[0096] Furthermore, in this embodiment, since the contact radiation portion 17i is formed of the same material as the radiation portion 17e, wear of the contact radiation portion 17i against the inner circumferential surface surrounding the through hole 20a can also be suppressed.

[0097] In this embodiment as well, the contact portion 17h and the contact radiation portion 17i may be provided at multiple locations in the intermediate portion 17a, or they may be provided in a portion located within the through hole 10a of the impeller 10.

[0098] Furthermore, in this embodiment, the contact radiation portion 17i is made of the same material as the radiation portion 17e, but it is also possible to form the contact radiation portion 17i with a different material than the radiation portion 17e. However, by making the contact radiation portion 17i the same material as the contact portion 17e, as in this embodiment, the contact radiation portion 17i and the radiation portion 17e can be formed continuously, which reduces the number of steps required during manufacturing.

[0099] [Fifth Embodiment] A turbo compressor 1 according to the fifth embodiment of the present invention will be described with reference to Figure 9. In Figure 9, only the tension bolt 17 and its surrounding area are shown. The turbo compressor 1 according to this embodiment employs the same configuration as the first embodiment described above, except for the parts that are not shown in Figure 9.

[0100] First, in the turbo compressor 1 according to this embodiment, the structure of the impeller 10 differs from that of the first embodiment described above.

[0101] As shown in section D of Figure 9, the impeller 10 has a main body portion 10b and an impeller radiating portion 10c.

[0102] The impeller radiating section 10c is laminated to the inner surface layer portion surrounding the through-hole 10a relative to the main body 10b. Furthermore, the impeller radiating section 10c is made of a material with a higher emissivity than the main body 10b.

[0103] Here, "a material with higher emissivity than the main body 10b" means that, when a comparative product is prepared that is made of the same material as the main body 10d but does not have the impeller radiation section 10c laminated, the impeller radiation section 10c has a higher emissivity than the comparative product. Specifically, "a material with higher emissivity than the main body 10b" means that, when comparing the comparative product and the impeller 10 of this embodiment, both with unoxidized surfaces and the same surface roughness, the impeller radiation section 10c has a higher emissivity than the comparative product.

[0104] The impeller radiating section 10c is formed on the inner circumferential surface 10d of the inner circumferential layer of the main body 10b using the same material and the same forming method (ceramic thermal spraying) as the radiating section 17e of the first embodiment. The impeller radiating section 10c is made of a material with a higher emissivity than the main body 10b. As described above, by using a material with an emissivity of 0.8 or higher as the impeller radiating section 10c, it can be said that it has a higher emissivity than the main body 10b.

[0105] In this embodiment, the impeller radiation section 10c is "another radiation section." Also, the main body section 10b in this embodiment is "the main body of the rotating member."

[0106] In this embodiment, the main body 10b of the impeller 10 is formed using a metal material with higher heat resistance than the pinion gear 15 (for example, austenitic stainless steel, precipitation-hardening stainless steel, or titanium).

[0107] In the turbo compressor 1 equipped with the impeller 10 having the above configuration, the impeller radiating portion 10c of the impeller 10 and the radiating portion 17e of the tension bolt 17 face each other with a gap G in between.

[0108] The turbo compressor 1 according to this embodiment has the above-described configuration and can obtain the same effects as the first embodiment.

[0109] Furthermore, in the turbo compressor 1 according to this embodiment, an impeller radiation section 10c is provided in at least a portion of the portion of the impeller 10 that faces the intermediate portion 17a of the tension bolt 17, so that radiant heat can be transferred to the tension bolt 17 more efficiently. Therefore, it is even more advantageous in suppressing the loosening or overtightening of the tension bolt 17 during the operation of the turbo compressor 1.

[0110] In the turbo compressor 1 according to this embodiment, the impeller radiating portion 10c is provided on the inner circumference surrounding the through hole 10a of the impeller 10, in the portion facing the radiating portion 17e of the tension bolt 17. However, similar radiating portions (other radiating portions) may be provided on members other than the impeller 10 among the members facing the outer circumference 17g of the tension bolt 17. For example, a radiating portion (other radiating portion) similar to the impeller radiating portion 10c may be provided on the inner circumference surrounding the through hole 20a of the intermediate member 20 in the second embodiment. The same effect can be obtained in this case as well.

[0111] [Differentiation] In the first to fifth embodiments described above, it was not stated whether the turbo compressor 1 was single-stage or multi-stage, but the present invention can be applied to either type.

[0112] Furthermore, in the first to fifth embodiments described above, ceramic thermal spraying was used as an example of a method for forming the radiating portion 17e, the contact radiating portion 17i, and the impeller radiating portion 10c. However, in the present invention, the radiating portion 17e, etc., can also be formed by painting. When forming the radiating portion 17e, etc., by painting, the radiating portion 17e, the contact radiating portion 17i, and the impeller radiating portion 10e can be formed with a coating film made of a material that has heat resistance and a higher emissivity than the main body portion 17d and the main body portion 10b.

[0113] Furthermore, in the first to fifth embodiments described above, when the radiating portion 17e, the contact radiating portion 17i, and the impeller radiating portion 10c are formed by a coating layer formed by ceramic thermal spraying, at least one of aluminachromia and alumina-titania is used as the specific material for forming the coating layer. However, the present invention is not limited thereto. Any material can be used for the formed radiating portion 17e, the contact radiating portion 17i, and the impeller radiating portion 10c that has a higher emissivity than the main body portion 17d and the main body portion 10b.

[0114] Furthermore, in the first to fifth embodiments described above, the dimension of the gap G was set to be 5% or more and 50% or less of the outer diameter D17 of the intermediate portion 17a of the tension bolt 17. However, in the present invention, the dimension of the gap G is not limited to this. It may be less than 5% or more than 50%. [Explanation of Symbols]

[0115] 1. Turbo compressor 10 Impeller (rotating component) 10a through hole 10c Impeller radiation section (other radiation sections) 15 Pinion Gear 15b Rotation axis 15c Female thread section 17 Tension bolts 17a middle part 17b First male thread section 17c Second male thread section 17d Main body 17e Radiant part 17h Contact part 17i Contact radiation section (another radiation section) 18 Net 20 Intermediate member (rotating member) 20a through hole

Claims

1. It is a turbo compressor, A rotating member including an impeller, the rotating member having a through hole formed at the center of rotation, A rotating shaft for rotating the aforementioned rotating member, wherein the rotating shaft has a female threaded portion formed at its tip, A tension bolt having a longitudinal intermediate portion located within the through hole, a first male threaded portion protruding from one opening of the through hole being screwed with a nut outside the impeller, and a second male threaded portion protruding from the opening opposite to the first opening being screwed with the female threaded portion, Equipped with, The tension bolt has, in the intermediate portion, a main body and a radiating portion stacked on the outer circumference of the main body in at least a portion of the longitudinal direction of the intermediate portion, The radiating portion is positioned so as to face the portion of the rotating member surrounding the radiating portion in a non-contact state with a gap in between, and is made of a material with a higher emissivity than the main body portion. The dimension of the gap is 5% to 50% of the diameter of the tension bolt. Turbo compressor.

2. The turbo compressor according to claim 1, wherein the radiating portion is a coating layer formed on the outer periphery of the main body by ceramic thermal spraying.

3. The aforementioned coating layer comprises ceramic containing at least one of aluminachromia and alumina-titania. A turbo compressor according to claim 2, comprising a MIC coating.

4. The rotating member comprises a rotating member body portion which is the main body of the rotating member, and other radiating portions laminated on at least a portion of the surface of the rotating member body portion facing the intermediate portion of the tension bolt, The turbo compressor according to claim 1, wherein the other radiating portion is made of a material with a higher emissivity than the rotating member body.

5. The radiating portion in the tension bolt is provided in a part of the longitudinal direction in the intermediate portion, The turbo compressor according to claim 1, wherein the tension bolt has a contact portion that contacts the rotating member in the portion of the intermediate part other than the portion where the radiating portion is provided.

6. The turbo compressor according to claim 5, wherein the tension bolt has a separate radiating portion provided in the contact portion that contacts the rotating member, and is made of a material with a higher emissivity than the main body portion.

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