Rotary machine

Abstract

A rotary machine according to one embodiment is provided with: a hollow shaft that extends in the axial direction and is rotatable; a connected body housed in the inner space of the hollow shaft in a state in which movement in the axial direction is restricted; a first impeller provided at one end of the hollow shaft and rotating together with the hollow shaft; a second impeller provided at the other end of the hollow shaft and rotating together with the hollow shaft; a first coupling body that couples the first impeller and the body to be coupled; and a second coupling body that couples the second impeller and the body to be coupled.

Description

Technical Field

[0001] The present disclosure relates to rotary machinery. Background Art

[0002] Well-known rotary machinery such as superchargers and compressors (for example, refer to Patent Documents 1 to 6 below). For example, Patent Document 1 describes an electric supercharger having: a turbine shaft, a bearing housing that supports the turbine shaft rotatably, a turbine impeller provided at one end of the turbine shaft, a compressor impeller connected to the other end of the turbine shaft by a shaft end nut, a motor stator fixed to the bearing housing, and a motor rotor fixed to the turbine shaft.

[0003] Patent Document 1: International Publication No. 2008 / 020511

[0004] Patent Document 2: Japanese Utility Model Laid-Open No. 59-141442

[0005] Patent Document 3: Japanese Utility Model Laid-Open No. 5-055742

[0006] Patent Document 4: Japanese Utility Model Laid-Open No. 7-023970

[0007] Patent Document 5: Japanese Patent Laid-Open No. 10-201152

[0008] Patent Document 6: Japanese Patent Laid-Open No. 2013-15098

[0009] In order to improve the performance of rotary machinery, it is desired to make the rotary machinery lighter. However, the constituent components of rotary machinery have natural vibration frequencies (eigenvalues) determined by the shape and size of the constituent components. If the rotational speed of the turbine shaft approaches the critical speed determined by the natural vibration frequency of the constituent components, vibrations will occur in the rotary machinery as the turbine shaft rotates. Especially in rotary machinery such as superchargers and compressors that require high output, since the rated speed is high, if the natural vibration frequency is low, resonance will occur in the rotary machinery and the vibrations are likely to become larger. Therefore, it is required to design the rotary machinery in consideration of the natural vibration frequencies of the respective constituent components. Summary of the Invention

[0010] Therefore, an object of the present disclosure is to provide a rotary machinery capable of suppressing vibrations.

[0011] A rotary machine according to one aspect of the present disclosure includes: a hollow shaft that extends in the axial direction and is rotatable; a connected body that is housed in the inner space of the hollow shaft in a state where movement in the axial direction is restricted; a first impeller that is provided at one end of the hollow shaft and rotates together with the hollow shaft; a second impeller that is provided at the other end of the hollow shaft and rotates together with the hollow shaft; a first connecting body that connects the first impeller and the connected body; and a second connecting body that connects the second impeller and the connected body.

[0012] According to various aspects of the present disclosure, vibration of the rotary machine can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a diagram schematically showing a rotary machine according to one embodiment.

[0014] Figure 2 is a diagram schematically showing a rotary machine according to another embodiment. DETAILED DESCRIPTION

[0015] A rotary machine according to one aspect of the present disclosure includes: a hollow shaft that extends in the axial direction and is rotatable; a connected body that is housed in the inner space of the hollow shaft in a state where movement in the axial direction is restricted; a first impeller that is provided at one end of the hollow shaft and rotates together with the hollow shaft; a second impeller that is provided at the other end of the hollow shaft and rotates together with the hollow shaft; a first connecting body that connects the first impeller and the connected body; and a second connecting body that connects the second impeller and the connected body.

[0016] In this aspect, by using the hollow shaft, lightening of the rotary machine can be achieved. In addition, the connected body is housed in the inner space of the hollow shaft, the first connecting body connected to the first impeller is connected to the connected body, and the second connecting body connected to the second impeller is connected to the connected body. Therefore, the first impeller and the second impeller can be connected while suppressing the lengths of the first connecting body and the second connecting body. As a result, a decrease in the natural vibration frequency of the first connecting body and the second connecting body can be suppressed, and the critical speed determined by the natural vibration frequency of the first connecting body and the second connecting body is less likely to coincide with the rotational speed of the rotary machine. Thereby, vibration of the rotary machine can be suppressed.

[0017] In one mode, it is also possible that the first impeller and the second impeller have bolt holes extending in the axial direction. The first connecting body includes: a first bolt inserted through the bolt hole of the first impeller, having one end connected to the connected body and the other end protruding from the bolt hole of the first impeller; and a first nut threadedly engaged with the first bolt to fix the first impeller to one end of the hollow shaft. The second connecting body includes: a second bolt inserted through the bolt hole of the second impeller, having one end connected to the connected body and the other end protruding from the bolt hole of the second impeller; and a second nut threadedly engaged with the second bolt to fix the second impeller to the other end of the hollow shaft. In this mode, a decrease in the natural vibration frequency of the first bolt and the second bolt can be suppressed, and thus vibration of the rotating machine can be suppressed.

[0018] In one mode, it is also possible that the connected body includes: a first part connected to one end of the first bolt, a second part connected to one end of the second bolt, and an axial force shaft extending in the axial direction and connecting the first part and the second part. A gap is formed between the axial force shaft and the inner surface of the hollow shaft. By forming a gap between the axial force shaft and the inner surface of the hollow shaft, the rotating machine can be made lighter.

[0019] In one mode, it is also possible that the hollow shaft includes a stopper protruding toward the inner space of the hollow shaft in a manner of being clamped between the connected body and the first impeller. The first nut and the second nut are respectively fastened to the first bolt and the second bolt in such a manner that the axial force generated in the first bolt is greater than the axial force generated in the second bolt. By making the axial force generated in the first bolt greater than the axial force generated in the second bolt, the connected body is urged by the stopper, thereby restricting the movement of the connected body in the axial direction. Therefore, the detachment of the connected body can be prevented.

[0020] In one mode, it is also possible that the length of the axial force shaft in the axial direction is shorter than the lengths of the first bolt and the second bolt. If the axial force shaft becomes longer, the natural vibration frequency of the axial force shaft decreases and vibration is likely to occur in the rotating machine. By making the length of the axial force shaft shorter than the lengths of the first bolt and the second bolt, vibration of the rotating machine can be suppressed.

[0021] In one mode, it is also possible that the connected body includes: a first part connected to one end of the first bolt and a second part connected to one end of the second bolt. The first part and the second part are fixed to the hollow shaft, and a gap is formed between the first part and the second part. By welding the first part and the second part of the connected body to the hollow shaft, the detachment of the connected body from the hollow shaft can be prevented. In addition, by forming a gap between the first part and the second part, the rotating machine can be made lighter.

[0022] In one mode, it can also be the distance in the axial direction between the connection point of the first part and one end of the first bolt and the connection point of the second part and one end of the second bolt, which is longer than the lengths of the first bolt and the second bolt respectively. By making the distance in the axial direction between the connection point of the first part and one end of the first bolt and the connection point of the second part and one end of the second bolt long, the lengths of the first bolt and the second bolt are shortened. Along with this, the decrease in the natural vibration frequencies of the first bolt and the second bolt is suppressed, and thus the vibration of the rotating machine can be suppressed.

[0023] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In addition, in the following description, the same or corresponding elements are denoted by the same reference numerals, and repeated explanations will not be repeated.

[0024] Figure 1 FIG. is a diagram schematically showing a rotating machine 1 of one embodiment. As Figure 1 shown, the rotating machine 1 includes: a hollow shaft 2, a connected body 3, a first impeller 4, a second impeller 5, a first connecting body 6, and a second connecting body 7. The rotating machine 1 is, for example, a two-stage compressor that further compresses the gas compressed by the first impeller 4 by the second impeller 5.

[0025] The hollow shaft 2 is a hollow rotating shaft having an internal space 10 and extends in the direction along the axis AX (hereinafter, referred to as the "axial direction"). The hollow shaft 2 is made of a metal such as stainless steel and has a cylindrical shape. The hollow shaft 2 is supported by a pair of bearings 25 so as to be rotatable about the axis AX. The pair of bearings 25 are respectively provided between the first impeller 4 and a rotor 26 described later, and between the second impeller 5 and the rotor 26.

[0026] The hollow shaft 2 has a stopper 8 that protrudes into the internal space 10 of the hollow shaft 2. The inner diameter of the hollow shaft 2 is narrower at the position where the stopper 8 is formed than at the position where the stopper 8 is not formed. The stopper 8 is arranged to be sandwiched between the connected body 3 and the first impeller 4 to restrict the movement of the connected body 3 in the axial direction.

[0027] The connected body 3 is accommodated in the internal space 10 of the hollow shaft 2. Specifically, the connected body 3 is detachably provided between the stopper 8 of the hollow shaft 2 and the second impeller 5. The connected body 3 may be made of the same material as the hollow shaft 2 or a different material from the hollow shaft 2. For example, the connected body 3 is made of a metal such as stainless steel or titanium.

[0028] The connected body 3 includes: a first part 11, a second part 12, and an axial force shaft 13. The first part 11 and the second part 12 are substantially cylindrical with the axis AX as the central axis, and are arranged separately from each other in the axial direction within the internal space 10 of the hollow shaft 2. The first part 11 is arranged closer to the first impeller 4 side than the second part 12. The outer diameters of the first part 11 and the second part 12 are substantially the same as the inner diameter of the hollow shaft 2 at the position where the stopper 8 is not formed. Therefore, the outer peripheral surfaces of the first part 11 and the second part 12 are in contact with the inner peripheral surface of the hollow shaft 2. On the other hand, the inner diameter of the stopper 8 is smaller than the outer diameters of the first part 11 and the second part 12. Therefore, when the connected body 3 slides toward the first impeller 4 side, the connected body 3 contacts the stopper 8 and restricts the movement toward the first impeller 4 side.

[0029] The first part 11 has: a first side surface 11a facing the first impeller 4 side, and a second side surface 11b facing the second impeller 5 side. An internal threaded hole 11c is formed in the first side surface 11a of the first part 11. The second part 12 has: a first side surface 12a facing the second impeller 5 side, and a second side surface 12b facing the first impeller 4 side. An internal threaded hole 12c is formed in the first side surface 12a of the second part 12.

[0030] The axial force shaft 13 extends in the axial direction and connects the first part 11 and the second part 12. That is, one end of the axial force shaft 13 is connected to the second side surface 11b of the first part 11, and the other end of the axial force shaft 13 is connected to the second side surface 12b of the second part 12. The axial force shaft 13 has the function of transmitting the axial force between the first connecting body 6 and the second connecting body 7. The diameter of the axial force shaft 13 is smaller than the inner diameter of the hollow shaft 2. Therefore, a gap 15 is formed between the outer peripheral surface of the axial force shaft 13 and the inner peripheral surface (inner surface) of the hollow shaft 2. By forming the gap 15, the weight reduction of the rotating machine 1 is achieved. In addition, the first part 11, the second part 12, and the axial force shaft 13 may also be integrally formed.

[0031] The first impeller 4 is provided at one end 2a of the hollow shaft 2. The first impeller 4 is, for example, a compressor impeller having blades for compressing gas. As Figure 1 shown, the back surface of the first impeller 4 abuts against one end 2a of the hollow shaft 2. A part of the first impeller 4 may also be inserted into the internal space 10 of the hollow shaft 2. A bolt hole 4a extending in the axial direction in a manner penetrating the first impeller 4 is formed in the first impeller 4.

[0032] The second impeller 5 is provided at the other end 2b of the hollow shaft 2. The second impeller 5 is, for example, a compressor impeller having blades for compressing gas. For example, the gas compressed by the first impeller 4 is supplied to the second impeller 5 through a flow path (not shown) and is further compressed by the second impeller 5. As Figure 1As shown, the back surface of the second impeller 5 abuts against the other end 2b of the hollow shaft 2. A part of the second impeller 5 may also be inserted into the internal space 10 of the hollow shaft 2. A bolt hole 5a extending in the axial direction is formed in the second impeller 5 so as to penetrate the second impeller 5.

[0033] The first connecting body 6 connects the first impeller 4 and the connected body 3. The first connecting body 6 includes a first bolt 21 and a first nut 22. The first bolt 21 is inserted through the bolt hole 4a of the first impeller 4 and extends in the axial direction. One end 21a of the first bolt 21 is fastened to the internal thread hole 11c of the first part 11 of the connected body 3 formed in the internal space 10 of the hollow shaft 2. The other end 21b of the first bolt 21 projects in the axial direction from the bolt hole 4a of the first impeller 4. The first nut 22 is threadedly engaged with the first bolt 21 from the other end 21b side. By tightening the first nut 22, the first impeller 4 is fixed to one end 2a of the hollow shaft 2.

[0034] The second connecting body 7 connects the second impeller 5 and the connected body 3. The second connecting body 7 includes a second bolt 23 and a second nut 24. The second bolt 23 is inserted through the bolt hole 5a of the second impeller 5 and extends in the axial direction. One end 23a of the second bolt 23 is fastened to the internal thread hole 12c of the second part 12 of the connected body 3 formed in the internal space 10 of the hollow shaft 2. The other end 23b of the second bolt 23 projects in the axial direction from the bolt hole 5a of the second impeller 5. The second nut 24 is threadedly engaged with the second bolt 23 from the other end 23b side. By tightening the second nut 24, the second impeller 5 is fixed to the other end 2b of the hollow shaft 2. As described later, the first nut 22 and the second nut 24 are respectively fastened to the first bolt 21 and the second bolt 23 such that the axial force F1 generated in the first bolt 21 is greater than the axial force F2 generated in the second bolt 23.

[0035] As described above, the axial force shaft 13 connects the first part 11 and the second part 12. Here, the length L1 of the axial force shaft 13 in the axial direction may also be shorter than the length L2 of the first bolt 21 and the length L3 of the second bolt 23. If the axial force shaft 13 is too long, the natural vibration frequency of the axial force shaft 13 may decrease and become a cause of vibration. By making the length L1 of the axial force shaft 13 shorter than the length L2 of the first bolt 21 and the length L3 of the second bolt 23, it is possible to suppress the decrease in the natural vibration frequency of the axial force shaft 13 and to suppress the vibration of the rotating machine 1.

[0036] The rotating machine 1 further includes a rotor 26 and a stator 27. The rotor 26 is disposed between a pair of bearings 25 and fixed to the outer peripheral surface of the hollow shaft 2. The rotor 26 includes one or more permanent magnets. The stator 27 is disposed to surround the rotor 26 from the outer side in the radial direction and fixed to a housing (not shown). The stator 27 includes a coil that generates a magnetic field and a stator core around which the coil is wound. When electric power is supplied to the coil of the stator 27, a force for rotating around the axis AX acts on the rotor 26 due to the interaction between the magnetic field generated by the coil and the magnetic field of the rotor 26. The force acting on the rotor 26 is transmitted to the hollow shaft 2, causing the hollow shaft 2 to rotate around the axis AX. That is, the rotor 26 and the stator 27 function as a motor that imparts a rotational force to the hollow shaft 2.

[0037] As the hollow shaft 2 rotates around the axis AX, the first impeller 4 and the second impeller 5 rotate together with the hollow shaft 2. The first impeller 4 and the second impeller 5 rotate, so that the gas supplied to the first impeller 4 is compressed, and the gas compressed by the first impeller 4 is further compressed by the second impeller 5.

[0038] Hereinafter, with reference to Figure 1 , an assembling method of the rotating machine 1 will be described. When assembling the rotating machine 1, first, the connected body 3 is pressed into the internal space 10 from the other end 2b side of the hollow shaft 2 so that the first side surface 11a of the first portion 11 abuts against the stopper 8. Next, the first impeller 4 is fixed to one end 2a of the hollow shaft 2 using the first connecting body 6. Specifically, the first bolt 21 is inserted into the bolt hole 4a of the first impeller 4, and one end 21a of the first bolt 21 is fastened to the internal thread hole 11c formed in the first portion 11 of the connected body 3. Next, the first nut 22 is threadedly engaged with the other end 21b of the first bolt 21 protruding from the bolt hole 4a, and the first nut 22 is tightened to fix the first impeller 4 to one end 2a of the hollow shaft 2. At this time, the tightening torque of the first nut 22 is adjusted so that an axial force F1 is generated in the first bolt 21. Axial force means the stress generated in the longitudinal direction of the bolt by the tightening of the nut.

[0039] Next, the second impeller 5 is fixed to the other end 2b of the hollow shaft 2 using the second connecting body 7. Specifically, the second bolt 23 is inserted into the bolt hole 5a of the second impeller 5, and one end 23a of the second bolt 23 is fastened to the internal thread hole 12c formed in the second portion 12 of the connected body 3. Next, the second nut 24 is threadedly engaged with the other end 23b of the second bolt 23 protruding from the bolt hole 5a, and the second nut 24 is tightened to fix the second impeller 5 to the other end 2b of the hollow shaft 2. At this time, the tightening torque of the second nut 24 is adjusted so that an axial force F2 is generated in the second bolt 23.

[0040] Here, the first nut 22 and the second nut 24 are respectively fastened to the first bolt 21 and the second bolt 23 in such a manner that the axial force F1 generated in the first bolt 21 is greater than the axial force F2 generated in the second bolt 23. That is, the tightening torque of the first nut 22 relative to the first bolt 21 is greater than the tightening torque of the second nut 24 relative to the second bolt 23. By making the axial force F1 greater than the axial force F2, a force that pulls the connected body 3 toward the first impeller 4 acts on the connected body 3, and the connected body 3 is urged by the stopper 8. Therefore, when the second nut 24 is fastened to the second bolt 23, the connected body 3 is prevented from moving toward the other end 2b side of the hollow shaft 2 due to the axial force F2 and falling off from the hollow shaft 2. That is, the movement of the connected body 3 in the axial direction is restricted.

[0041] As described above, in the rotating machine 1, by using the hollow shaft 2 having the internal space 10, the weight reduction of the rotating machine 1 can be achieved. On the other hand, when the first impeller 4 and the second impeller 5 are mounted on the hollow shaft 2, how to fix the first impeller 4 and the second impeller 5 to the hollow shaft 2 becomes a problem. For example, it may be considered to connect the first impeller 4 and the second impeller 5 with a single bolt, but in this case, the bolt will inevitably be long, so the natural vibration frequency of the bolt decreases. Along with this, the critical speed determined by the natural vibration frequency of the bolt approaches the rotational speed of the hollow shaft 2, and thus vibration may occur in the rotating machine 1 when the hollow shaft 2 rotates.

[0042] In contrast, in the rotating machine 1, the first bolt 21 is used to connect the connected body 3 and the first impeller 4, and the second bolt 23 is used to connect the connected body 3 and the second impeller 5. That is, different bolts are used to fasten the first impeller 4 and the second impeller 5 to the connected body 3. Thereby, compared with the case of connecting the first impeller 4 and the second impeller 5 with a single bolt, the first impeller 4 and the second impeller 5 can be fixed to the hollow shaft 2 using relatively short bolts. Therefore, the critical speed determined by the natural vibration frequencies of the first bolt 21 and the second bolt 23 is less likely to coincide with the rotational speed of the hollow shaft 2. As a result, vibration of the rotating machine 1 can be suppressed.

[0043] In addition, in the rotating machine 1, the length L1 of the axial force shaft 13 is shorter than the length L2 of the first bolt 21 and the length L3 of the second bolt 23, so a decrease in the natural vibration frequency of the axial force shaft 13 can be suppressed. Therefore, the critical speed determined by the natural vibration frequency of the axial force shaft 13 is less likely to coincide with the rotational speed of the hollow shaft 2, and as a result, vibration of the rotating machine 1 can be suppressed.

[0044] Next, a rotating machine according to another embodiment will be described. Figure 2 FIG. schematically shows a rotating machine 1A according to another embodiment. In the following description, the differences from the above-described rotating machine 1 will be mainly described, and repeated descriptions will be omitted.

[0045] As Figure 2 shown, the hollow shaft 2 of the rotary machine 1A does not have a stopper 8, which is different from the hollow shaft 2 of the rotary machine 1 Figure 1 shown. Therefore, the hollow shaft 2 of the rotary machine 1A has a constant inner diameter over the entire region in the axial direction. In addition, the rotary machine 1A is provided with a connected body 30 in place of the connected body 3. The connected body 30 includes a first part 31 and a second part 32. The first part 31 and the second part 32 are substantially cylindrical with the axis AX as the central axis, and are arranged separately from each other in the axial direction in the inner space 10 of the hollow shaft 2.

[0046] The first part 31 is arranged closer to the first impeller 4 side than the second part 32. The outer diameters of the first part 31 and the second part 32 are substantially the same as the inner diameter of the hollow shaft 2. Therefore, the outer peripheral surfaces of the first part 31 and the second part 32 are in contact with the inner peripheral surface of the hollow shaft 2. A gap 20 is formed between the first part 31 and the second part 32. The gap 20 is formed over the entire region between the first part 31 and the second part 32. By forming the gap 20, the rotary machine 1A is made lighter. Different from the connected body 3, the connected body 30 does not have an axial force shaft 13, and the first part 31 and the second part 32 are not connected to each other. Instead, the first part 11 and the second part 12 are respectively fixed to the hollow shaft 2 by welding. Thereby, the movement of the connected body 30 in the axial direction is restricted.

[0047] The first part 31 has: a first side surface 31a facing the first impeller 4 side, and a second side surface 31b facing the second impeller 5 side. An internal threaded hole 31c is formed in the first side surface 31a of the first part 11. The second part 32 has: a first side surface 32a facing the second impeller 5 side, and a second side surface 32b facing the first impeller 4 side. An internal threaded hole 32c is formed in the first side surface 32a of the second part 12. One end 21a of the first bolt 21 is fastened to the internal threaded hole 31c of the first part 11. One end 23a of the second bolt 23 is fastened to the internal threaded hole 32c. The first nut 22 and the second nut 24 can also be fastened to the first bolt 21 and the second bolt 23 such that the axial force F1 generated in the first bolt 21 is equal to the axial force F2 generated in the second bolt 23.

[0048] In Figure 2In [the structure], the axial distance L4 between the connection point 35 of the first part 31 of the connected body 30 and one end 21a of the first bolt 21, and the connection point 36 of the second part 32 of the connected body 30 and one end 23a of the second bolt 23 is shorter than the length L2 of the first bolt 21 and the length L3 of the second bolt 23. However, in one embodiment, the distance L4 between the connection point 35 and the connection point 36 may also be longer than the length L2 of the first bolt 21 and the length L3 of the second bolt 23. By making the distance L4 between the connection point 35 and the connection point 36 long, the lengths L2 of the first bolt 21 and L3 of the second bolt 23 are shortened. As a result, a decrease in the natural vibration frequency of the first bolt 21 and the second bolt 23 can be suppressed, and as a result, vibration of the rotary machine 1A caused by resonance can be suppressed.

[0049] Similar to the rotary machine 1, in the rotary machine 1A, by using the hollow shaft 2 having the internal space 10, weight reduction of the rotary machine 1 can be achieved. In addition, the first impeller 4 and the second impeller 5 are fastened to the connected body 3 by using the first bolt 21 and the second bolt 23. Therefore, compared with the case where the first impeller 4 and the second impeller 5 are connected by one bolt, the first impeller 4 and the second impeller 5 can be fixed to the hollow shaft 2 with relatively short bolts. Therefore, the critical speed determined by the natural vibration frequency of the first bolt 21 and the second bolt 23 is not likely to coincide with the rotational speed of the hollow shaft 2, and vibration of the rotary machine 1 can be suppressed. And, in the rotary machine 1A, the axial force shaft 13 is not provided, and accordingly, the rotary machine 1A can be further lightened.

[0050] As described above, the rotary machines of various embodiments have been described, but the present disclosure is not limited to the above-described embodiments and can be configured in various modified forms without changing the gist of the disclosure. That is, it should be noted that the above-described embodiments are for illustrative purposes and do not limit the scope of the present disclosure.

[0051] For example, in the above-described embodiment, an example in which the rotary machines 1 and 1A are used as two-stage compressors has been described, but the rotary machines 1 and 1A can also be used as superchargers for internal combustion engines of ships or vehicles. When the rotary machine is used as a supercharger, the first impeller 4 rotates by the flow of the exhaust gas discharged from the internal combustion engine. The second impeller 5 rotates along with the rotation of the first impeller 4, compresses the obtained air, and supplies the compressed air to the internal combustion engine. In addition, the rotary machines 1 and 1A can also be an electric turbocharger that supplies the compressed air to a fuel cell.

[0052] Explanation of Reference Numerals

[0053] 1, 1A... Rotary machinery; 2... Hollow shaft; 2a... One end of the hollow shaft; 2b... The other end of the hollow shaft; 3, 30... Connected body; 4... First impeller; 5... Second impeller; 4a, 5a... Bolt holes; 6... First connecting body; 7... Second connecting body; 8... Limiter; 10... Internal space; 11, 31... First part; 12, 32... Second part; 13... Axial force axis; 15, 20... Gap; 21... First bolt; 21a... One end of the first bolt; 21b... The other end of the first bolt; 22... First nut; 23... Second bolt; 23a... One end of the second bolt; 23b... The other end of the second bolt; 24... Second nut; 35, 36... Connection points; F1, F2... Axial force.

Claims

1. A rotating machine, characterized in that, Comprising: A hollow shaft that extends in the axial direction and is rotatable; A connected body that is accommodated in the internal space of the hollow shaft in a state where movement in the axial direction is restricted; A first impeller that is provided at one end of the hollow shaft and rotates together with the hollow shaft; A second impeller that is provided at the other end of the hollow shaft and rotates together with the hollow shaft; A first connecting body that connects the first impeller and the connected body; And A second connecting body that connects the second impeller and the connected body.

2. The rotary machine according to claim 1, wherein The first impeller and the second impeller have bolt holes extending in the axial direction, The first connecting body includes: a first bolt that is inserted through the bolt hole of the first impeller, has one end connected to the connected body and the other end protruding from the bolt hole of the first impeller; and a first nut that is threadedly engaged with the first bolt to fix the first impeller to one end of the hollow shaft, The second connecting body includes: a second bolt that is inserted through the bolt hole of the second impeller, has one end connected to the connected body and the other end protruding from the bolt hole of the second impeller; and a second nut that is threadedly engaged with the second bolt to fix the second impeller to the other end of the hollow shaft.

3. The rotary machine according to claim 2, wherein The connected body includes: a first part connected to one end of the first bolt, a second part connected to one end of the second bolt, and an axial force shaft that extends in the axial direction and connects the first part and the second part, A gap is formed between the axial force shaft and the inner surface of the hollow shaft.

4. The rotary machine according to claim 3, wherein The hollow shaft includes a limiter that protrudes toward the internal space of the hollow shaft in a manner of being clamped between the connected body and the first impeller, The first nut and the second nut are respectively tightened to the first bolt and the second bolt in such a way that the axial force generated by the first bolt is greater than the axial force generated by the second bolt.

5. The rotary machine according to claim 3 or 4, wherein The length of the axial force shaft in the axial direction is shorter than the lengths of the first bolt and the second bolt.

6. The rotary machine according to claim 2, wherein The connected body includes: a first part connected to one end of the first bolt, and a second part connected to one end of the second bolt, The first part and the second part are fixed to the hollow shaft, A gap is formed between the first part and the second part.

7. The rotary machine according to claim 6, wherein The distance in the axial direction between the connection point of the first part and one end of the first bolt and the connection point of the second part and one end of the second bolt is longer than the lengths of the first bolt and the second bolt respectively.

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