Turbo compressor
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- MITSUBISHI HEAVY IND ENGINE & TURBOCHARGER LTD
- Filing Date
- 2025-01-24
- Publication Date
- 2026-07-30
Smart Images
Figure JP2025002217_30072026_PF_FP_ABST
Abstract
Description
Turbo-compressor
[0001] The present disclosure relates to a turbo-compressor.
[0002] A refrigerator cools by the sensible heat of a gas circulating in the gas phase. That is, for example, the refrigerator uses air as a refrigerant, generates high-pressure and high-temperature air by a compressor, cools the high-pressure and high-temperature air in a cooler (heat exchanger), then generates low-pressure and low-temperature air by an expander, and cools an object to be cooled by the sensible heat of the low-pressure and low-temperature air. A turbo-compressor is applied to the refrigerator. The turbo-compressor has an electric motor, a compressor wheel, and a turbine wheel connected to the rotating shaft of the electric motor. As such a turbo-compressor, for example, there is one described in Patent Document 1.
[0003] Japanese Patent Application Laid-Open No. 2023-553578
[0004] The turbo-compressor cools the high-pressure and high-temperature air generated by the compressor wheel in a cooler and then supplies it to the turbine wheel to generate low-pressure and low-temperature air. However, the electric motor rotates the rotor by flowing a current through the stator coil that constitutes the stator, and the rotating shaft integrated with the rotor rotates due to the attractive and repulsive forces of the magnetic force generated. Therefore, there is a problem that the stator (stator coil) becomes high temperature, heat is transmitted to the turbine wheel side, and the temperature of the low-pressure and low-temperature air cooled in the cooler rises.
[0005] The present disclosure solves the above-described problems, and an object thereof is to provide a turbo-compressor that suppresses the transmission of heat from the electric motor to the turbine wheel side and improves performance.
[0006] To achieve the above objectives, the turbo compressor of the present disclosure comprises a housing having a stator with a cylindrical shape on its inner circumference; a rotating shaft having a rotor disposed inside the housing and facing the stator; a turbine wheel fixed to one axial side of the rotating shaft; a compressor wheel fixed to the other axial side of the rotating shaft; a pair of journal bearings disposed on one and the other axial side of the rotating shaft to rotatably support the rotating shaft relative to the housing; a thrust bearing disposed on one axial side of the rotating shaft to rotatably support the rotating shaft relative to the housing; a space partitioned between one axial end of the stator and the end face of the housing; and a low thermal conductivity portion disposed between the end face of the housing and the turbine wheel, having a lower thermal conductivity than the housing.
[0007] The turbo compressor of this disclosure can improve performance by suppressing heat transfer from the electric motor to the turbine wheel.
[0008] Figure 1 is a schematic diagram showing a refrigeration unit of the first embodiment. Figure 2 is a cross-sectional view showing a turbo compressor of the first embodiment. Figure 3 is a cross-sectional view showing a turbo compressor of the second embodiment. Figure 4 is a cross-sectional view showing a turbo compressor of the third embodiment. Figure 5 is a cross-sectional view showing a turbo compressor of the fourth embodiment. Figure 6 is a cross-sectional view showing a turbo compressor of the fifth embodiment. Figure 7 is a cross-sectional view showing a first modified example of a low-heat-conductivity section in a turbo compressor. Figure 8 is a cross-sectional view showing a second modified example of a low-heat-conductivity section in a turbo compressor. Figure 9 is a cross-sectional view showing a third modified example of a low-heat-conductivity section in a turbo compressor. Figure 10 is a cross-sectional view showing a turbo compressor of the sixth embodiment.
[0009] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. However, these embodiments do not limit the present disclosure, and where there are multiple embodiments, they may be combinations of these embodiments. Furthermore, the components in the embodiments include those readily conceivable by those skilled in the art, those that are substantially identical, and those that are equivalent.
[0010] [First Embodiment] <Refrigeration Unit> Figure 1 is a schematic diagram showing the refrigeration unit of the first embodiment.
[0011] As shown in Figure 1, the refrigeration unit 10 comprises a compressor unit 11, a water-cooled heat exchanger (first cooler) 12, a brine heat exchanger (second cooler, brine cooler) 13, and a regenerative heat exchanger 14. The refrigeration unit 10 cools the object to be cooled by flowing a refrigerant gas through the compressor unit 11, the water-cooled heat exchanger 12, the brine heat exchanger 13, and the regenerative heat exchanger 14. Here, it is preferable to use a working fluid such as air, nitrogen, argon, helium, or an organic medium as the refrigerant gas, but it is not limited to these working fluids.
[0012] The compressor unit 11 comprises a drive unit 21, a compressor 22, and an expander 23. The compressor unit 11 has a compressor 22 and an expander 23 driven by a drive shaft 24 of the drive unit 21. The drive unit 21 is an electric motor and has a drive shaft 24 that can be driven and rotated. The compressor 22 is connected to one end of the drive shaft 24 in the axial direction, and the expander 23 is connected to the other end in the axial direction. The compressor 22 has a compressor wheel (not shown) attached to one end of the drive shaft 24, and the expander 23 has a turbine wheel (not shown) attached to the other end of the drive shaft 24.
[0013] The compressor 22 compresses the refrigerant gas to produce high-pressure refrigerant gas. The compressor 22 is connected to the water-cooled heat exchanger 12 by piping L1. The water-cooled heat exchanger 12 cools the high-pressure refrigerant gas compressed by the compressor 22. The water-cooled heat exchanger 12 is connected to an external cooler 31, and the cooling medium supplied from the cooler 31 cools the high-pressure refrigerant gas compressed by the compressor 22.
[0014] The water-cooled heat exchanger 12 is connected to the expander 23 by piping L2. The expander 23 recovers expansion energy from the high-pressure refrigerant gas cooled in the water-cooled heat exchanger 12 to generate low-pressure refrigerant gas. The expander 23 is connected to the brine heat exchanger 13 by piping L3. The brine heat exchanger 13 cools the brine (object to be cooled) with the low-pressure refrigerant gas from which the expansion energy was recovered in the expander 23. The brine heat exchanger 13 is connected to, for example, a freezer (object to be cooled) 32, and cools the freezer 32 with the cooled brine. The brine heat exchanger 13 is connected to the compressor 22 by piping L4.
[0015] The regenerative heat exchanger 14 is located in piping L2 and L4. In this case, piping L2 includes piping L21 connecting the water-cooled heat exchanger 12 and the regenerative heat exchanger 14, and piping L22 connecting the regenerative heat exchanger 14 and the expander 23. Piping L4 includes piping L41 connecting the brine heat exchanger 13 and the regenerative heat exchanger 14, and piping L42 connecting the regenerative heat exchanger 14 and the compressor 22. The regenerative heat exchanger 14 performs heat exchange between the refrigerant gas sent from the water-cooled heat exchanger 12 to the expander 23 and the refrigerant gas returned from the brine heat exchanger 13 to the compressor 22. That is, the regenerative heat exchanger 14 cools the refrigerant gas sent from the water-cooled heat exchanger 12 to the expander 23 through piping L2 using the low-temperature refrigerant gas returned from the brine heat exchanger 13 to the compressor 22 through piping L4.
[0016] Furthermore, a pipe L5 is provided that connects a pipe L2 that sends refrigerant gas from the water-cooled heat exchanger 12 to the expander 23 and a pipe L4 that returns refrigerant gas from the brine heat exchanger 13 to the compressor 22. A balance valve 33 is provided in the pipe L5. When the balance valve 33 is open, it bypasses a portion of the refrigerant gas flowing through the pipe L2 to the pipe L4.
[0017] In the refrigeration unit 10, when the drive unit 21 is driven, the drive shaft 24 rotates, and the compressor 22 and expander 23 operate. When the compressor 22 operates, it compresses the refrigerant gas to generate high-pressure refrigerant gas, which is sent to the water-cooled heat exchanger 12 through piping L1. The water-cooled heat exchanger 12 cools the high-pressure refrigerant gas compressed by the compressor 22 and sends it to the expander 23 through piping L2. When the expander 23 operates, it recovers expansion energy from the high-pressure refrigerant gas cooled in the water-cooled heat exchanger 12 to generate low-pressure refrigerant gas, which is sent to the brine heat exchanger 13 through piping L3. The brine heat exchanger 13 cools the brine with the low-pressure refrigerant gas from which the expansion energy was recovered in the expander 23, and returns it to the compressor 22 through piping L4. The regenerative heat exchanger 14 cools the refrigerant gas sent from the water-cooled heat exchanger 12 to the expander 23 through the pipe L2 using the low-temperature refrigerant gas returned from the brine heat exchanger 13 to the compressor 22 through the pipe L4.
[0018] Furthermore, when the refrigeration unit 10 is started, the balance valve 33 is opened, and a portion of the refrigerant gas flowing through piping L2 is bypassed and sent to piping L4. If the capacity of the compressor 22 and the expander 23 are different, the flow rates of the refrigerant gas flowing through piping L2 and L4 are balanced. After a predetermined time has elapsed since the refrigeration unit 10 was started, the balance valve 33 is closed.
[0019] The refrigeration unit 10 is a closed-loop type refrigeration unit comprising a compressor unit 11, a water-cooled heat exchanger 12, a brine heat exchanger 13, and a regenerative heat exchanger 14, but it is not limited to this type. For example, the refrigeration unit 10 may be an open-loop type refrigeration unit. In this case, the second cooler is, for example, a cooler that directly supplies and discharges refrigerant gas to the inside of the freezer chamber (object to be cooled) 32.
[0020] <Turbo Compressor> Figure 2 is a cross-sectional view showing a turbo compressor according to the first embodiment.
[0021] As shown in Figures 1 and 2, the turbo compressor 40 is applied to the refrigeration unit 10. The turbo compressor 40 is a compressor unit 11 that constitutes the refrigeration unit 10. Like the compressor unit 11, the turbo compressor 40 has a drive unit 21, a compressor 22, and an expander 23. The drive unit 21 is an electric motor and is driven and connected to the compressor 22 and the expander 23 by a drive shaft 24.
[0022] The drive unit 21 comprises a housing 41 and a rotating shaft 42 (drive shaft 24).
[0023] The housing 41 includes a motor housing 51 and a bearing housing 52. The motor housing 51 has a cylindrical shape with the other axial side (left side in Figure 2) closed. That is, the motor housing 51 has a cylindrical portion 51a and a disc portion 51b located on the other axial side of the cylindrical portion 51a. The cylindrical portion 51a functions as a support for the stator 61, which will be described later, and the disc portion 51b functions as a bearing housing on the compressor 22 side. The bearing housing 52 has a disc shape and is located on one axial side (right side in Figure 2) of the motor housing 51. The bearing housing 52 is detachably connected to one axial end of the motor housing 51 by a plurality of bolts (not shown).
[0024] In the motor housing 51, the other axial opening, that is, the other axial opening in the cylindrical portion 51a, is closed by the disc portion 51b, and one axial opening is closed by the bearing housing 52. Therefore, the housing 41 becomes hollow when the bearing housing 52 is fastened to the motor housing 51.
[0025] The motor housing 51 has a stator 61 fixed to the inner circumference of the cylindrical portion 51a. The stator 61 has a cylindrical shape.
[0026] The stator 61 has an insulating portion (not shown). The insulating portion is formed by molding, in which molten resin is filled into the main part of the stator 61 and cured. The insulating portion covers at least the ends (coil ends 63a, 63b) of the stator coil 63 in the direction of the axial center O of the stator 61.
[0027] The rotating shaft 42 constitutes the drive shaft 24. The rotating shaft 42 is located inside the housing 41. The rotating shaft 42 is positioned along an axis O concentric with the housing 41 and is rotatably supported by the housing 41 around the axis O. A rotor 64 is fixed to the outer circumference of the rotating shaft 42 at an intermediate position in the axial direction. The rotor 64 has a rotor core (permanent magnet) 65. The rotor core 65 is cylindrical and is fixed to the outer circumference of the rotating shaft 42.
[0028] The stator 61 and rotor 64 have their inner and outer circumferential surfaces facing each other in the radial direction. A gap is provided between the inner and outer circumferential surfaces of the stator 61 and rotor 64. Therefore, when current flows through the stator coil 63 of the stator 61, the rotor 64 rotates due to the attractive and repulsive forces of the generated magnetic force, and the rotating shaft 42 outputs a rotational force.
[0029] The housing 41 has an air bearing 66 on one axial side and an air bearing 67 on the other axial side. The air bearings 66 and 67 function as journal bearings. The air bearing 66 is cylindrical and is mounted on the bearing housing 52. The air bearing 67 is cylindrical and is mounted on the disc portion 51b of the motor housing 51. On the other hand, the rotating shaft 42 has a shaft portion 42a on one axial side of the rotor 64 and a shaft portion 42b on the other axial side of the rotor 64. The rotating shaft 42 is rotatably supported in the housing 41 by the support of the air bearing 66 at shaft portion 42a and the air bearing 67 at shaft portion 42b.
[0030] A gap is maintained between the inner surface of the air bearing 66 and the outer surface of the shaft portion 42a of the rotating shaft 42. A gap is maintained between the inner surface of the air bearing 67 and the outer surface of the shaft portion 42b of the rotating shaft 42. The air bearings 66 and 67 supply air to the respective gaps between the air bearings 66 and 67 and the shaft portions 42a and 42b of the rotating shaft 42, thereby supporting the rotating shaft 42 so that it can rotate freely at the axis O of the housing 41.
[0031] A thrust disc 68 is fixed to one side of the rotating shaft 42 in the axial direction. The thrust disc 68 functions as a thrust bearing. The thrust disc 68 is fixed to the end of the shaft portion 42a of the rotating shaft 42. The thrust disc 68 rotates integrally with the rotating shaft 42. The bearing housing 52 is provided with a thrust space portion 69 that has an inverted circular shape. The thrust disc 68 is positioned in the thrust space portion 69. The thrust space portion 69 has an axial clearance between it and the thrust disc 68 and communicates with the air bearing 66.
[0032] The housing 41 has an expander 23 positioned on the bearing housing 52 side. The expander 23 has a turbine housing 71 and a turbine wheel 72. The turbine housing 71 is fastened with a plurality of bolts (not shown) in contact with the ends of the motor housing 51 and the bearing housing 52. The turbine wheel 72 is positioned inside the turbine housing 71. The turbine wheel 72 is fixed to one axial end (shaft portion 42a) of the rotating shaft 42 by a bolt 73 so as to be able to rotate integrally. The expander 23, consisting of the turbine housing 71 and the turbine wheel 72, is provided with an intake port (not shown), a spiral-shaped scroll portion 74, and a discharge port 75.
[0033] Furthermore, the compressor 22 is positioned on the disc portion 51b side of the motor housing 51 in the housing 41. The compressor 22 has a compressor housing 81 and a compressor wheel 82. The compressor housing 81 is fastened with a plurality of bolts (not shown) while in contact with the disc portion 51b of the motor housing 51. The compressor wheel 82 is positioned inside the compressor housing 81. The compressor wheel 82 is fixed to the other axial end (shaft portion 42b) of the rotating shaft 42 by bolts 83 so as to be able to rotate integrally. The compressor 22, with the compressor housing 81 and compressor wheel 82, is provided with an intake port 84, a diffuser portion 85, a spiral-shaped scroll portion 86, and a discharge port (not shown).
[0034] As shown in Figures 1 and 2, the expander 23 has piping L2 connected to its intake port and piping L3 connected to its discharge port 75. The compressor 22 has piping L42 connected to its intake port 84 and piping L1 connected to its discharge port.
[0035] When the compressor wheel 82 rotates, air is drawn in from the piping L42 through the intake port 84, accelerated and pressurized by the centrifugal force of the compressor wheel 82, and after being decelerated by the diffuser section 85, it flows around the scroll section 86 and is discharged into the piping L1 from the discharge port. When high-pressure air is supplied to the intake port from the piping L22, the high-pressure air flows around the scroll section 74, causing the turbine wheel 72 to rotate. A portion of the expansion energy generated when the high-pressure air expands is recovered to assist in driving the compressor 22, and the expanded low-pressure air is discharged into the piping L3 from the discharge port.
[0036] <Thermal Insulation Structure> As shown in Figure 2, the turbo compressor 40 has an expander 23 positioned on one side of the axis O relative to the drive unit 21, and a compressor 22 positioned on the other side. The turbo compressor 40 has a thermal insulation structure that suppresses the transfer of heat generated by the electric motor constituting the drive unit 21 to the expander 23. The turbo compressor 40 has a space 101 partitioned between one axial end of the stator 61 and the end face of the housing 41. The space 101 is partitioned between the coil end 63a of one end of the stator coil 63 and the bearing housing 52.
[0037] The stator 61 has a stator coil 63 wound around a stator iron core 62, with coil ends 63a and 63b exposed. The stator 61 has an insulating portion (not shown) molded from a resin material, at least on the coil ends 63a and 63b. The space 101 is located between the insulating portion of the coil end 63a and the bearing housing 52. The space 101 is ring-shaped and prevents contact between the insulating portion of the coil end 63a and the bearing housing 52 by separating them. As a result, heat from the stator 61 is less likely to be transferred to the bearing housing 52 by the space 101, and the temperature rise of the compressed air (refrigerant gas) due to the high temperature of the expander 23 is suppressed.
[0038] Furthermore, the turbo compressor 40 has a low thermal conductivity portion 102 positioned between the end face of the housing 41 and the turbine wheel 72, which has a lower thermal conductivity than the housing 41. The low thermal conductivity portion 102 is a space, for example, provided in the bearing housing 52. The low thermal conductivity portion 102 is ring-shaped and is a space formed in the bearing housing 52. The space constituting the low thermal conductivity portion 102 may be formed directly in the bearing housing 52, or it may be formed by embedding a hollow member. As a result, the area in which the bearing housing 52 and the turbine housing 71 are in direct contact is reduced by the low thermal conductivity portion (space) 102, making it difficult for heat from the bearing housing 52 to be transferred to the turbine housing 71, and suppressing the temperature rise of the compressed air (refrigerant gas) due to the high temperature of the expander 23.
[0039] <Airflow path> The turbo compressor 40 has an airflow path 110. The airflow path 110 has a first airflow path 111 and a second airflow path 112. The first airflow path 111 extracts compressed air supplied to the expander 23 from the scroll section 74 and supplies it to the thrust bearing, that is, the thrust space 69 of the thrust disc 68. The second airflow path 112 extracts compressed air supplied to the expander 23 from the scroll section 74 and supplies it through the radially outer side of the stator 61 to a pair of journal bearings, that is, the low-pressure side gap of the air bearing 67 and the high-pressure side gap of the air bearing 66.
[0040] <First Airflow Channel> The first airflow channel 111 is provided in the bearing housing 52. The bearing housing 52 is provided with a first radial airflow channel 121 that runs along the radial direction. The first radial airflow channel 121 is provided along the radial direction of the bearing housing 52 on one axial side of the stator 61. The inner diameter end of the first radial airflow channel 121 communicates with the inner diameter side of the thrust space 69. The bearing housing 52 is provided with an opening 122 on the expander 23 side, and the turbine housing 71 is provided with an opening 123 on the bearing housing 52 side. The opening 122 is provided radially outward from the low heat conductivity section 102. The opening 122 of the bearing housing 52 and the opening 123 of the turbine housing 71 are at the same position in the radial and circumferential directions and communicate with each other, connecting the scroll section 74 and the axial airflow channel 124. The first air passage 111 is composed of a first radial air passage 121 and openings 122 and 123.
[0041] The compressed air supplied to the scroll section 74 of the expander 23 is extracted from the scroll section 74 through openings 123 and 122 into the first radial air passage 121 due to the pressure difference. The compressed air extracted into the first radial air passage 121 is supplied to the inner diameter side of the thrust space 69 and flows to the outer diameter side due to centrifugal force. At this time, the rotating shaft 42 is supported at a predetermined position in the axial direction by the compressed air supplied between the thrust disc 68 and the thrust space 69. In addition, the support surfaces supporting the thrust disc 68 (one axial surface and the other surface in the thrust space 69) are cooled by the compressed air.
[0042] <Second Airflow Channel> The second airflow channel 112 is provided in the housing 41. Specifically, the second airflow channel 112 is provided in the motor housing 51 and the bearing housing 52. The second airflow channel 112 has a first radial airflow channel 121, an axial airflow channel 124, and a second radial airflow channel 125. The axial airflow channel 124 is provided radially outward on the stator 61 along the axial direction of the motor housing 51. The outer diameter end of the first radial airflow channel 121 extends to the motor housing 51 and communicates with one end of the axial airflow channel 124.
[0043] The second radial air flow path 125 is provided along the radial direction of the motor housing 51 on the other axial side of the stator 61. That is, the second radial air flow path 125 is provided along the radial direction on the disk portion 51b of the motor housing 51. One end of the second radial air flow path 125 communicates with the other end of the axial air flow path 124, and the other end communicates with the air bearing 67 that constitutes the journal bearing.
[0044] Specifically, an annular space portion 126 is provided outside the shaft portion 42b of the rotating shaft 42 in the disk portion 51b. The space portion 126 communicates with the gap between the inner peripheral surface of the air bearing 67 and the outer peripheral surface of the shaft portion 42b. The other end of the second radial air flow path 125 communicates with the space portion 126. Also, the air bearing 67 communicates with the air bearing 66 through the gap between the stator core 62 and the rotor core 65.
[0045] Note that only one of each of the radial air flow paths 121 and 125 and the axial air flow path 124 is provided at a predetermined position in the circumferential direction in the housing 41. However, a plurality of each of the radial air flow paths 121 and 125 and the axial air flow path 124 may be provided at a predetermined position in the circumferential direction in the housing 41.
[0046] The compressed air supplied to the scroll portion 74 of the expander 23 is evacuated from the scroll portion 74 through the opening 123 and the opening 122 to the first radial air flow path 121 due to the pressure difference. The compressed air evacuated to the first radial air flow path 121 flows into the axial air flow path 124, flows inward in the radial direction through the second radial air flow path 125, and is supplied from the space portion 126 to the air bearing 67. That is, the compressed air is supplied to the gap between the inner peripheral surface of the air bearing 67 and the outer peripheral surface of the shaft portion 42b of the rotating shaft 42, so that the rotating shaft 42 floats and is supported at a predetermined position in the radial direction, and the air bearing 67 is appropriately cooled.
[0047] The compressed air of the air bearing 67 flows into the gap between the stator 61 and the rotor 64, cooling the stator iron core 62 and the stator coil 63 of the stator 61. Then, the compressed air that has cooled the stator 61 is supplied to the air bearing 66. Here, the compressed air is supplied into the gap between the inner peripheral surface of the air bearing 66 and the outer peripheral surface of the shaft portion 42a of the rotating shaft 42, causing the rotating shaft 42 to float and be supported at a predetermined position in the radial direction, and at the same time, the air bearing 66 is appropriately cooled.
[0048] <Discharge Flow Path> The air flow path 110 includes a discharge flow path 113 together with the first air flow path 111 and the second air flow path 112. The discharge flow path 113 combines the compressed air flowing through the first air flow path 111 and the compressed air flowing through the second air flow path 112 and discharges them to the outside. The discharge flow path 113 is provided in the bearing housing 52 on the expander 23 side.
[0049] The discharge flow path 113 is provided along the radial direction in the bearing housing 52. One end of the discharge flow path 113 communicates with the thrust space portion 69, and the other end is open to the outside. The compressed air flowing through the first air flow path 111 flows from the thrust space portion 69 into the discharge flow path 113. Also, the compressed air flowing through the second air flow path 112 flows from the air bearing 66 into the discharge flow path 113. The compressed air that has merged in the discharge flow path 113 is discharged to the outside by the discharge flow path 113. The compressed air discharged from the discharge flow path 113 is returned to the suction port 84 in the compressor 22.
[0050] The turbo compressor 40 of the first embodiment provides a space portion 101 between the coil end 63a of the stator coil 63 in the stator 61 and the bearing housing 52, and provides a low heat conduction portion 102 between the end face portion of the housing 41 and the turbine wheel 72. Therefore, the heat of the stator 61 is less likely to be transmitted to the bearing housing 52 through the space portion 101, and the heat of the bearing housing 52 is less likely to be transmitted to the turbine housing 71 through the low heat conduction portion 102, suppressing the temperature rise of the compressed air (refrigerant gas) due to the high temperature of the expander 23.
[0051] [Second Embodiment] Figure 3 is a cross-sectional view showing a turbo compressor of the second embodiment. Components having the same functions as those in the first embodiment described above are denoted by the same reference numerals, and detailed descriptions are omitted.
[0052] As shown in Figure 3, the turbo compressor 40A includes a drive unit 21, a compressor 22, and an expander 23. The turbo compressor 40A has a space 101 between one axial end of the stator 61 and the end face of the housing 41, and a low heat conductivity section 102 between the end face of the housing 41 and the turbine wheel 72.
[0053] The turbo compressor 40A has an air passage 110 consisting of a first air passage 111, a second air passage 112, and a discharge passage 113. The turbo compressor 40A also has a third air passage 114 as part of the air passage 110. The third air passage 114 is cylindrical in shape and is located radially outside the stator 61, and radially inside the axial air passage 124.
[0054] The third air passage 114 has an inlet 131 at one end in the axial direction and an outlet 132 at the other end in the axial direction. The inlet 131 is connected to an air passage (not shown) that extracts and supplies a portion of the compressed air supplied to the turbine wheel 72 of the expander 23. The compressed air supplied from the inlet 131 flows through the third air passage 114 in both the circumferential and axial directions. The outlet 132 is connected to an air passage (not shown) that supplies the compressed air that has flowed through the third air passage 114 to the intake port 84 of the compressor 22.
[0055] The compressed air extracted from the expander 23 is supplied from the inlet 131 to the third air passage 114, where it flows circumferentially and axially. At this time, the stator 61 of the drive unit 21 is cooled. The compressed air that has cooled the stator is discharged from the outlet 132 and supplied to the compressor 22.
[0056] In addition, the third air passage 114 is supplied with a portion of the compressed air supplied to the turbine wheel 72 of the expander 23, but it may also be supplied with a portion of the low-pressure air discharged from the turbine wheel 72 of the expander 23. Furthermore, the third air passage 114 may be supplied with cooling air or cooling water from an external source.
[0057] [Third Embodiment] Figure 4 is a cross-sectional view showing a turbo compressor of the third embodiment. Components having the same functions as those in the first embodiment described above are denoted by the same reference numerals, and detailed descriptions are omitted.
[0058] As shown in Figure 4, the turbo compressor 40B includes a drive unit 21, a compressor 22, and an expander 23. The turbo compressor 40B has a space 101 between one axial end of the stator 61 and the end face of the housing 41, and a low heat conduction section 102 between the end face of the housing 41 and the turbine wheel 72.
[0059] The turbo compressor 40B has an air passage 110 consisting of a first air passage 111B, a second air passage 112, and a discharge passage 113. The first air passage 111B has a first radial air passage 121, an external air passage 141, and a connecting passage 142. The second air passage 112 has a first radial air passage 121, an axial air passage 124, and a second radial air passage 125.
[0060] The first air passage 111B is provided radially in the bearing housing 52, and its inner diameter end communicates with the inner diameter side of the thrust space 69. The external air passage 141 extracts and supplies a portion of the low-pressure air discharged from the expander 23. The communication passage 142 is provided in the motor housing 51, with the downstream end of the external air passage 141 connected to one end and the other end communicating with the axial air passage 124.
[0061] Low-pressure air extracted from the discharge port 75 of the expander 23 is sent to the communication passage 142 through the external air passage 141 and supplied to the axial air passage 124. The low-pressure air supplied to the axial air passage 124 is supplied to the thrust space 69 through the first radial air passage 121. At this time, the rotating shaft 42 is supported at a predetermined position in the axial direction by the low-pressure air supplied between the thrust disc 68 and the thrust space 69. In addition, the support surfaces supporting the thrust disc 68 (one axial surface and the other surface in the thrust space 69) are cooled by the low-pressure air.
[0062] Furthermore, the low-pressure air supplied to the axial air passage 124 flows radially inward from the axial air passage 124 through the second radial air passage 125 and is supplied to the air bearing 67 from the space 126. At this time, the air bearing 67 functions due to the low-pressure air, causing the rotating shaft 42 to float and be supported at a predetermined position in the radial direction, and the air bearing 67 is properly cooled. The low-pressure air from the air bearing 67 flows into the gap between the stator 61 and the rotor 64, cooling the stator core 62 and stator coil 63 of the stator 61. Then, the low-pressure air that has cooled the stator 61 is supplied to the air bearing 66, causing the air bearing 66 to function, causing the rotating shaft 42 to float and be supported at a predetermined position in the radial direction, and the air bearing 66 is properly cooled.
[0063] In addition, the external air passage 141 was supplied with a portion of the low-pressure air discharged from the turbine wheel 72 of the expander 23, but it may also be supplied with a portion of the low-pressure air supplied to the expander 23.
[0064] [Fourth Embodiment] Figure 5 is a cross-sectional view showing a turbo compressor of the fourth embodiment. Components having the same functions as those in the first embodiment described above are denoted by the same reference numerals, and detailed descriptions are omitted.
[0065] As shown in Figure 5, the turbo compressor 40C includes a drive unit 21, a compressor 22, and an expander 23. The turbo compressor 40C has a space 101 between one axial end of the stator 61 and the end face of the housing 41, and a low heat conduction section 102 between the end face of the housing 41 and the turbine wheel 72.
[0066] The turbo compressor 40C has an air passage 110 which includes a first air passage 111, a second air passage 112C, and a discharge passage 113. The first air passage 111 has a first radial air passage 121 and openings 122 and 123. The second air passage 112C has a first radial air passage 121, an axial air passage 124C, and a second radial air passage 125C.
[0067] The axial air passage 124C is provided in the motor housing 51. The axial air passage 124C is cylindrical in shape and is provided radially outward from the stator 61 in the motor housing 51. The second radial air passage 125C is provided in the motor housing 51. The second radial air passage 125C is ring-shaped and is provided on the compressor wheel 82 side of the motor housing 51. One end of the axial air passage 124C communicates with the other end of the first radial air passage 121, and the other end communicates with one end of the second radial air passage 125C.
[0068] Compressed air extracted from the scroll section 74 of the expander 23 is supplied to the first radial air passage 121 through openings 123 and 122. The compressed air supplied to the first radial air passage 121 is then supplied to the thrust space 69 through the first radial air passage 121. At this time, the rotating shaft 42 is supported at a predetermined position in the axial direction by the compressed air supplied between the thrust disc 68 and the thrust space 69. In addition, the support surfaces supporting the thrust disc 68 (one axial surface and the other surface in the thrust space 69) are cooled by the compressed air.
[0069] Furthermore, the compressed air supplied to the first radial air passage 121 is supplied to the axial air passage 124C, and as it flows through the axial air passage 124C, it cools the stator 61. The compressed air flowing through the axial air passage 124C flows radially inward through the second radial air passage 125C and is supplied to the air bearing 67 from the space 126. At this time, the compressed air causes the air bearing 67 to function, the rotating shaft 42 to float and be supported at a predetermined radial position, and the air bearing 67 is properly cooled. The compressed air from the air bearing 67 flows into the gap between the stator 61 and the rotor 64, cooling the stator iron core 62 and stator coil 63 of the stator 61. Then, the compressed air that has cooled the stator 61 is supplied to the air bearing 66, the compressed air causes the air bearing 66 to function, the rotating shaft 42 to float and be supported at a predetermined radial position, and the air bearing 66 is properly cooled.
[0070] In this embodiment, the first air passage 111 is composed of a first radial air passage 121 and openings 122 and 123, but it may also have an external air passage, as in the third embodiment.
[0071] [Fifth Embodiment] Figure 6 is a cross-sectional view of a turbo compressor according to the fifth embodiment. Components having the same functions as those in the first embodiment described above are denoted by the same reference numerals, and detailed descriptions are omitted.
[0072] As shown in Figure 6, the turbo compressor 40D includes a drive unit 21, a compressor 22, and an expander 23. The turbo compressor 40D has a space 101 between one axial end of the stator 61 and the end face of the housing 41, and a low heat conduction section 102D between the end face of the housing 41 and the turbine wheel 72.
[0073] The low thermal conductivity section 102D is positioned between the end face of the housing 41 and the turbine wheel 72. The low thermal conductivity section 102D is ring-shaped and positioned in a space formed in the bearing housing 52. The low thermal conductivity section 102D is made of a material with a lower thermal conductivity than the housing 41. In this case, the housing 41 is made of, for example, aluminum, and the low thermal conductivity section 102D is made of, for example, an insulating material, Inconel, or stainless steel. Suitable insulating materials include, for example, glass wool (inorganic fiber), rock wool (inorganic fiber), cellulose fiber (wood fiber), insulation board (wood fiber), and extruded polystyrene foam (foamed plastic).
[0074] The bearing housing 52 has a ring shape, and a cylindrical member 151 is mounted on its inner circumference. The cylindrical member 151 has a ring-shaped notch 152 on its outer circumference on the turbine housing 71 (turbine wheel 72) side. The low thermal conductivity portion 102D is mounted in the notch 152 of the cylindrical member 151. When the low thermal conductivity portion 102D is in a soft material, it can be mounted in the notch 152 of the cylindrical member 151 by deforming the low thermal conductivity portion 102D.
[0075] Therefore, even if the temperature of the bearing housing 52 rises due to the heat of the stator 61, the heat from the bearing housing 52 is less likely to be transferred to the turbine housing 71 by the low thermal conductivity part 102D attached to the cylindrical member 151, thereby suppressing the temperature rise of the compressed air (refrigerant gas) due to the high temperature of the expander 23.
[0076] Figure 7 is a cross-sectional view showing a first modified example of a low-heat-conductivity section in a turbo compressor. As shown in Figure 7, the cylindrical member 151 mounted on the inner circumference of the bearing housing 52 has a main body member 151a and a locking member 151b. The main body member 151a is ring-shaped and has an L-shaped cross-section. The locking member 151b is also ring-shaped. The main body member 151a and the locking member 151b form a notch 152. The low-heat-conductivity section 102D is superimposed on the main body member 151a, and the locking member 151b is fixed to the main body member 151a, thereby becoming one with the cylindrical member 151. The cylindrical member 151 and the low-heat-conductivity section 102D are fixed together to the stepped portion 52a of the bearing housing 52.
[0077] Figure 8 is a cross-sectional view showing a second modified example of the low-heat-conductivity section in a turbo compressor. As shown in Figure 8, the cylindrical member 161, which is mounted on the inner circumference of the bearing housing 52, has a ring-shaped notch 162 on its outer circumference on the turbine housing 71 (turbine wheel 72) side. The low-heat-conductivity section 102D is mounted in the notch 162 of the cylindrical member 161. The outer diameter of the cylindrical member 161 is the same as the outer diameter of the low-heat-conductivity section 102D. With the low-heat-conductivity section 102D mounted in the notch 162 of the cylindrical member 161, it is mounted on the stepped portion 52a of the bearing housing 52.
[0078] Figure 9 is a cross-sectional view showing a third modified example of the low-heat-conductivity section in a turbo compressor. As shown in Figure 9, the cylindrical member 161 mounted on the inner circumference of the bearing housing 52 has a main body member 161a and a locking member 161b. The main body member 161a is ring-shaped and has an L-shaped cross-section. The outer diameter of the main body member 161a is the same as the outer diameter of the low-heat-conductivity section 102D. The locking member 161b is ring-shaped. The main body member 161a and the locking member 161b form a notch 162. The low-heat-conductivity section 102D is superimposed on the main body member 161a, and the locking member 161b is fixed to the main body member 161a, making it an integral part of the cylindrical member 161. The cylindrical member 161 and the low-heat-conductivity section 102D are fixed together to the stepped portion 52a of the bearing housing 52.
[0079] [Sixth Embodiment] Figure 10 is a cross-sectional view showing a turbo compressor according to the sixth embodiment. Components having the same functions as those in the first embodiment described above are denoted by the same reference numerals, and detailed descriptions are omitted.
[0080] As shown in Figure 10, the turbo compressor 40E includes a drive unit 21E, a compressor 22, and an expander 23. The turbo compressor 40E has a space 101 between one axial end of the stator 61 and the end face of the housing 41, and a low heat conduction portion 102 between the end face of the housing 41 and the turbine wheel 72.
[0081] The drive unit 21E comprises a housing 41 and a rotating shaft 42E. The rotating shaft 42E is located inside the housing 41. The rotating shaft 42E is positioned along an axis O concentric with the housing 41 and is rotatably supported by the housing 41 about the axis O. The rotating shaft 42 has a shaft portion (first shaft portion) 42c at its axial center, a shaft portion (second shaft portion) 42a on one side of the shaft portion 42c, and a shaft portion (third shaft portion) 42b on the other side of the shaft portion 42c. A rotor 64 is fixed to the shaft portion 42c of the rotating shaft 42E. The rotor 64 has a rotor core (permanent magnet) 65.
[0082] The rotating shaft 42E is formed by three separate components: shaft portion 42c, shaft portion 42a, and shaft portion 42b, which are joined together to form a single integrated unit. At least shaft portion 42a is made of a material with lower thermal conductivity than shaft portion 42c. For example, shaft portions 42b and 42c are made of carbon steel, while shaft portion 42a is made of Inconel or stainless steel. The bearing housing 52 is provided with a ring-shaped sealing member 70 on its inner circumference. The outer circumferential surface of one side of shaft portion 42a of the rotating shaft 42 contacts the sealing member 70. The sealing member 70 is made of a material with lower thermal conductivity than shaft portion 42a. For example, the sealing member 70 is made of a resin material.
[0083] The drive unit 21E rotates the rotor 64 by passing an electric current through the stator coil 63 that constitutes the stator 61, causing the rotating shaft 42E, which is integrated with the rotor 64, to rotate. At this time, the stator coil 63 becomes hot, and therefore the rotating shaft 42E also becomes hot. However, since the shaft portion 42a and the sealing member 70 are made of materials with low thermal conductivity, the heat from the rotating shaft 42E is less likely to be transmitted to the bearing housing 52 and turbine housing 71 by the shaft portion 42a and the sealing member 70, thereby suppressing the rise in the temperature of the compressed air due to the high temperature of the expander 23.
[0084] In this example, the rotating shaft 42E is assembled as a single unit by joining together shaft portions 42c, 42a, and 42b as separate components. Alternatively, shaft portions 42c and 42b may be made as a single unit, and shaft portion 42a as a separate component, which can then be joined together to form a single unit.
[0085] [Effects of this embodiment] The turbo compressor according to the first embodiment comprises a housing 41 having a stator 61 with a cylindrical shape on its inner circumference, a rotating shaft 42 having a rotor 64 disposed inside the housing 41 and facing the stator 61, a turbine wheel 72 fixed to one side of the rotating shaft 42 in the axial direction, a compressor wheel 82 fixed to the other side of the rotating shaft 42 in the axial direction, a pair of air bearings (journal bearings) 66, 67 disposed on one and the other side of the rotating shaft 42 in the axial direction to rotatably support the rotating shaft 42 with respect to the housing 41, a thrust disc (thrust bearing) 68 disposed on one side of the rotating shaft 42 in the axial direction to rotatably support the rotating shaft 42 with respect to the housing 41, a space 101 partitioned between one end of the stator 61 in the axial direction and the end face of the housing 41, and low thermal conductivity parts 102, 102D disposed between the end face of the housing 41 and the turbine wheel 72 and having a lower thermal conductivity than the housing 41.
[0086] In the turbo compressor according to the first embodiment, the heat from the stator 61 is blocked by the space 101 and is less likely to be transmitted to the bearing housing 52, and the heat from the bearing housing 52 is blocked by the low thermal conductivity parts 102 and 102D and is less likely to be transmitted to the turbine housing 71. As a result, the transfer of heat from the drive unit (electric motor) 21 to the turbine wheel 72 is suppressed, the temperature rise of the compressed air (refrigerant gas) due to the high temperature of the expander 23 is suppressed, and performance can be improved.
[0087] The turbo compressor according to the second embodiment is the turbo compressor according to the first embodiment, further comprising a stator 61 having a cylindrical stator core 62 and a stator coil 63 wound around the stator core 62, wherein at least one end and the other end of the stator coil 63 in the axial direction of the stator 61 are covered by the leading edge, and the space 101 is partitioned between one end of the stator coil 63 and the end face of the housing 41. This makes it possible to efficiently block the heat of the stator 61 with the space 101 and suppress the overheating of the bearing housing 52.
[0088] The turbo compressor according to the third embodiment is a turbo compressor according to the first or second embodiment, and further, the low heat conductivity section 102 is a space. This makes it possible to simplify the structure.
[0089] The turbo compressor according to the fourth embodiment is a turbo compressor according to the first or second embodiment, wherein the low thermal conductivity section 102D is made of a material with a lower thermal conductivity than the housing 41. This makes it possible to efficiently block the heat of the bearing housing 52 with the low thermal conductivity section 102D and suppress the temperature rise of the turbine housing 71.
[0090] The fifth embodiment of the turbo compressor is a turbo compressor according to any one of the first to fourth embodiments, further comprising a motor housing 51 positioned radially outward on the stator 61 and a bearing housing 52 connected to the turbine wheel 72 side of the motor housing 51. The bearing housing 52 is provided with ring-shaped notches 152 and 162 on the outer circumference on the turbine wheel 72 side, and the low heat conductivity parts 102 and 102D are mounted in the notches 152 and 162. This allows the low heat conductivity parts 102 and 102D to be easily assembled in the correct position, improving ease of assembly.
[0091] The turbo compressor according to the sixth embodiment is a turbo compressor according to any one of the first to fifth embodiments, further comprising: first air passages 111, 111B that extract a portion of the compressed air in the turbine wheel 72 and supply it to the thrust disc 68; and second air passages 112, 112C that extract a portion of the compressed air in the turbine wheel 72 and supply it to a pair of air bearings 66, 67 through the radially outer side of the stator 61. This enables the thrust disc 68 and the pair of air bearings 66, 67 to operate properly.
[0092] The turbo compressor according to the seventh embodiment is a turbo compressor according to the sixth embodiment, further comprising a discharge passage 113 that combines the compressed air flowing through the first air passages 111, 111B and the compressed air flowing through the second air passages 112, 112C and discharges them to the outside. This allows for the smooth discharge of compressed air.
[0093] The turbo compressor according to the eighth embodiment is a turbo compressor according to any one of the first to seventh embodiments, and further has a third air passage 114 that extracts a portion of the compressed air in the turbine wheel 72 and flows it radially outward from the stator 61. This allows the stator 61 to be properly cooled.
[0094] The turbo compressor according to the ninth embodiment is a turbo compressor according to any one of the first to seventh embodiments, further comprising: a shaft portion (first shaft portion) 42c on which a rotor 64 is mounted on its outer circumference; a shaft portion (second shaft portion) 42a supported on one side of the shaft portion 42c in the axial direction by one air bearing 66; and a shaft portion (third shaft portion) 42b supported on the other side of the shaft portion 42c in the axial direction by the other air bearing 67, wherein at least the shaft portion 42a is formed of a material with lower thermal conductivity than the shaft portion 42c. As a result, heat transmitted from the stator 61 to the shaft portion 42c of the rotating shaft 42 via the rotor 64 is blocked by the shaft portion 42a and is less likely to be transmitted to the bearing housing 52 and turbine housing 71, thereby suppressing the temperature rise of the compressed air (refrigerant gas) due to the high temperature of the expander 23.
[0095] The turbo compressor according to the tenth embodiment is a turbo compressor according to the ninth embodiment, further comprising a rotating shaft 42, the shaft portion 42a of which is supported by a bearing housing 52 via a sealing member 70, and the sealing member 70 is made of a material with a lower thermal conductivity than the shaft portion 42a. As a result, the heat transmitted to the shaft portion 42a of the rotating shaft 42 is blocked by the sealing member 70 and is less likely to be transmitted to the bearing housing 52 and turbine housing 71, thereby suppressing the temperature rise of the compressed air (refrigerant gas) due to the high temperature of the expander 23.
[0096] 10 Refrigeration unit 11 Compressor unit 12 Water-cooled heat exchanger (first cooler) 13 Brine heat exchanger (second cooler, brine cooler) 14 Regenerative heat exchanger 21, 21E Drive unit 22 Compressor 23 Expander 24 Drive shaft 31 Cooler 32 Refrigeration chamber 33 Balance valve 40, 40A, 40B, 40C, 40D, 40E Turbo compressor 41 Housing 42, 42E Rotating shaft 42a Shaft section (second shaft section) 42b Shaft section (third shaft section) 42c Shaft section (first shaft section) 51 Motor housing 51a Cylindrical section 51b Disc section 52 Bearing housing 61 Stator 62 Stator iron core 63 Stator coil 63a, 63b Coil end 64 Rotor 65 Rotor iron core 66, 67 Air bearing (journal bearing) 68 Thrust disc (thrust bearing) 69 Thrust space 70 Seal member 71 Turbine housing 72 Turbine wheel 73 Bolt 74 Scroll section 75 Discharge port 81 Compressor housing 82 Compressor wheel 83 Bolt 84 Inlet 85 Diffuser section 86 Scroll section 101 Space 102, 102D Low thermal conductivity section 110 Air passage 111, 111B First air passage 112, 112C Second air passage 113 Discharge passage 114 Third air passage 121 First radial air passage 122, 123 Opening 124, 124C Axial air passage 125 Second radial air passage 126 Space 131 Inlet 132 Outlet section 141 External air passage 142 Connecting passages 151, 161 Cylindrical members 152, 162 Notches
Claims
1. A turbo compressor comprising: a housing having a stator with a cylindrical shape on its inner circumference; a rotating shaft having a rotor disposed inside the housing and facing the stator; a turbine wheel fixed to one end of the rotating shaft in the axial direction; a compressor wheel fixed to the other end of the rotating shaft in the axial direction; a pair of journal bearings disposed on one and the other side of the rotating shaft in the axial direction to rotatably support the rotating shaft relative to the housing; a thrust bearing disposed on one end of the rotating shaft in the axial direction to rotatably support the rotating shaft relative to the housing; a space partitioned between one end of the stator in the axial direction and the end face of the housing; and a low thermal conductivity portion disposed between the end face of the housing and the turbine wheel, having a lower thermal conductivity than the housing.
2. The turbo compressor according to claim 1, wherein the stator comprises a cylindrical stator core and a stator coil wound around the stator core, and at least one end and the other end of the stator coil in the axial direction of the stator are covered by a leading edge, and the space is defined between one end of the stator coil and the end face of the housing.
3. The turbo compressor according to claim 1, wherein the low heat conductivity portion is a space portion.
4. The turbo compressor according to claim 1, wherein the low thermal conductivity section is made of a material with lower thermal conductivity than the housing.
5. The turbo compressor according to claim 4, wherein the housing comprises a motor housing positioned radially outward of the stator and a bearing housing connected to the turbine wheel side of the motor housing, the bearing housing having a ring-shaped notch on its outer circumference on the turbine wheel side, and the low heat conductivity portion being mounted in the notch.
6. The turbo compressor according to claim 1, further comprising: a first air passage for extracting a portion of the compressed air in the turbine wheel and supplying it to the thrust bearing; and a second air passage for extracting a portion of the compressed air in the turbine wheel and supplying it to the pair of journal bearings through the radially outer side of the stator.
7. The turbo compressor according to claim 6, further comprising a discharge channel for combining the compressed air that has flowed through the first air channel and the compressed air that has flowed through the second air channel and discharging them to the outside.
8. The turbo compressor according to claim 1, further comprising a third air passage for extracting a portion of the compressed air in the turbine wheel and flowing it radially outward from the stator.
9. The turbo compressor according to claim 1, wherein the rotating shaft has a first shaft portion on which the rotor is mounted on its outer circumference, a second shaft portion supported on one side of the first shaft portion in the axial direction by one of the journal bearings, and a third shaft portion supported on the other side of the first shaft portion in the axial direction by the other of the journal bearings, and at least the second shaft portion is formed of a material with lower thermal conductivity than the first shaft portion.
10. The rotating shaft is supported in the housing via a sealing member at the first shaft portion, and the sealing member is made of a material with lower thermal conductivity than the first shaft portion. The turbo compressor according to claim 9.