Pump device for liquefied gas

Abstract

The present invention relates to a pump device for transferring extremely low-temperature liquefied gas such as liquid hydrogen and liquefied natural gas, in particular to a pump device having an electric motor as a drive source for a pump. A pump device is provided with: a pump (1) having an impeller (2); a rotating shaft (5) to which the impeller (2) is fixed; and a motor (7) for rotating the rotating shaft (5) and the impeller (2). A rotor assembly (21) of an electric motor (7) is provided with: a motor rotor (40) fixed to a rotating shaft (5); side rings (41) disposed on both sides of the motor rotor (40); and a sealing cover (42) fixed to the outer peripheral surface of the side ring (41). The sealing cover (42) is made of glass fibers.

Description

Technical Field

[0001] The present invention relates to a pump device for transferring extremely low-temperature liquefied gas such as liquid hydrogen and liquefied natural gas, and more particularly to a pump device having an electric motor as a driving source of the pump. Background Art

[0002] In recent years, there has been a trend to reduce carbon dioxide: the demand for pump devices for transporting extremely low-temperature liquids such as liquid hydrogen (boiling point -253°C) and liquefied natural gas (boiling point -160°C) is increasing. For example, liquid hydrogen is sometimes used as fuel for power generation gas turbines that do not emit carbon dioxide, and is also used as fuel for aircraft engines.

[0003] Liquefied gases such as liquid hydrogen and liquefied natural gas have extremely low specific gravity, so pumps for liquefied gases are required to rotate at high speeds. In particular, in applications where aircraft engines require high discharge pressures and where miniaturization of pumps is required, the rotation speed of pumps can sometimes reach tens of thousands of revolutions per minute. -1 .

[0004] The pump device generally includes: a pump having an impeller; and an electric motor for rotating the impeller. As the impeller rotates, liquefied gas is sucked into the pump, pressurized by the rotation of the impeller, and then discharged from the pump. A portion of the pressurized liquefied gas flows into the motor chamber where the motor is arranged, filling the motor chamber. Therefore, the motor is immersed in the liquefied gas.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 9-19093 Summary of the invention

[0008] However, the material used for the motor rotor of the electric motor is brittle to liquefied gas, and the strength of the motor rotor in contact with liquefied gas decreases over time. In addition, as mentioned above, the motor rotor rotates at an ultra-high speed, thereby exerting a large centrifugal force on the motor rotor, generating a large stress on the motor rotor. As a result, a part of the motor rotor may be deformed or damaged.

[0009] Therefore, the present invention provides a pump device having a structure that isolates a motor rotor from liquefied gas and can enhance the mechanical strength of the motor rotor that rotates at an ultra-high speed.

[0010] In one embodiment, a pump device for liquefied gas is provided, comprising: a pump having an impeller; a rotating shaft to which the impeller is fixed; and an electric motor for rotating the rotating shaft and the impeller, the electric motor comprising: a rotor assembly capable of rotating integrally with the rotating shaft; and a motor stator having a coil and a stator core, the coil surrounding the rotor assembly, the rotor assembly comprising: a motor rotor fixed to the rotating shaft; side rings arranged on both sides of the motor rotor; and a sealing cover fixed to the outer peripheral surface of the side ring, the sealing cover being made of glass fiber.

[0011] In one embodiment, the side ring is made of glass fiber.

[0012] In one embodiment, the pump device further comprises: a balance ring arranged on the outside of the side ring in the axial direction of the rotating shaft; and a non-magnetic metal cover fixed to the outer peripheral surface of the balance ring, the non-magnetic metal cover and the balance ring forming a closed space for the sealing cover, the side ring, and the motor rotor to be arranged.

[0013] In one embodiment, the pump device further includes a coil protection cover disposed radially inward of an end portion of the coil, wherein the coil protection cover is made of a non-metallic material.

[0014] In one embodiment, a pump device for liquefied gas is provided, comprising: a pump having an impeller; a rotating shaft to which the impeller is fixed; and an electric motor for rotating the rotating shaft and the impeller, the electric motor comprising: a rotor assembly capable of rotating integrally with the rotating shaft; and a motor stator having a coil and a stator core, the coil surrounding the rotor assembly, the rotor assembly comprising: a motor rotor fixed to the rotating shaft; a balancing ring arranged on both sides of the motor rotor; a sealing cover fixed to the outer peripheral surface of the balancing ring; and a cylindrical reinforcement cover arranged on the outer peripheral surface of the sealing cover, the sealing cover being made of non-magnetic metal, and the cylindrical reinforcement cover being made of glass fiber.

[0015] In one embodiment, both ends of the cylindrical reinforcement cover are located inside the balance ring in the axial direction of the rotating shaft.

[0016] In one embodiment, the motor rotor comprises: a plurality of rotor bars arranged in a circumferential direction of the rotating shaft; and end rings fixed to both ends of the plurality of rotor bars, and both ends of the cylindrical reinforcement cover are located inside the end rings in the axial direction of the rotating shaft.

[0017] In one embodiment, the pump device further includes side rings disposed on both sides of the motor rotor, the motor rotor includes a plurality of permanent magnets arranged in a circumferential direction of the rotating shaft, and the side rings are made of a non-metallic material.

[0018] In one embodiment, the side ring is made of glass fiber.

[0019] In one embodiment, the pump device further includes a coil protection cover disposed radially inward of an end portion of the coil, wherein the coil protection cover is made of a non-metallic material.

[0020] In one embodiment, a pump device for liquefied gas is provided, comprising: a pump having an impeller; a rotating shaft to which the impeller is fixed; and an induction motor for rotating the rotating shaft and the impeller, the induction motor comprising: a rotor assembly capable of rotating integrally with the rotating shaft; and a motor stator having a coil and a stator core, the coil surrounding the rotor assembly, the rotor assembly comprising: a motor rotor having a plurality of rotor bars arranged in a circumferential direction of the rotating shaft, and end rings connected to both ends of the plurality of rotor bars; a balance ring in contact with the end ring; a first reinforcement cover surrounding the outer circumferential surface of the end ring; and a second reinforcement cover surrounding the plurality of rotor bars.

[0021] In one embodiment, the first reinforcing cover is made of glass fiber.

[0022] In one embodiment, the second reinforcing cover is made of glass fiber.

[0023] In one embodiment, the thickness of the first reinforcement cover is greater than the thickness of the second reinforcement cover.

[0024] In one embodiment, the second reinforcement cover is made of a non-magnetic metal, and the second reinforcement cover is fixed to the balance ring.

[0025] Effects of the Invention

[0026] The sealing cover and the side ring form a sealed space in which the motor rotor is arranged. Therefore, the motor rotor can be protected from the liquefied gas or its evaporated gas existing in the motor chamber of the motor. In addition, the sealing cover made of glass fiber can enhance the mechanical strength of the motor rotor. Therefore, when a large centrifugal force is applied to the motor rotor rotating at an ultra-high speed, deformation and damage of various components constituting the motor rotor can be prevented.

[0027] The sealing cover and the balance ring form a sealed space in which the motor rotor is arranged. Therefore, the motor rotor can be protected from the liquefied gas or its evaporated gas existing in the motor chamber of the motor. In addition, the cylindrical reinforcement cover made of glass fiber can enhance the mechanical strength of the motor rotor. Therefore, when a large centrifugal force is applied to the motor rotor rotating at ultra-high speed, deformation and damage of various components constituting the motor rotor can be prevented.

[0028] The first reinforcement cover, the second reinforcement cover, and the balance ring can protect the motor rotor from the liquefied gas or its boil-off gas existing in the motor chamber of the motor. In addition, the first reinforcement cover and the second reinforcement cover made of non-magnetic material can enhance the mechanical strength of the motor rotor. Therefore, when a large centrifugal force is applied to the motor rotor rotating at an ultra-high speed, deformation and damage of the end ring and the rotor guide bar constituting the motor rotor can be prevented. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a cross-sectional view showing one embodiment of a pump device for transferring liquefied gas.

[0030] Figure 2 Yes means Figure 1 An enlarged cross-sectional view of a portion of a pump assembly is shown.

[0031] Figure 3 yes Figure 2 A cross-sectional view of a rotor assembly.

[0032] Figure 4 This is an enlarged cross-sectional view showing a part of a pump device according to another embodiment.

[0033] Figure 5 This is an enlarged cross-sectional view showing a part of a pump device according to still another embodiment.

[0034] Figure 6 This is an enlarged cross-sectional view showing a part of a pump device according to still another embodiment.

[0035] Figure 7 yes Figure 6 A cross-sectional view of a rotor assembly.

[0036] Figure 8 This is an enlarged cross-sectional view showing a part of a pump device according to still another embodiment.

[0037] Fig. 9 This is an enlarged cross-sectional view showing a part of a pump device according to still another embodiment.

[0038] Fig.10 This is an enlarged cross-sectional view showing a part of a pump device according to still another embodiment.

[0039] Fig.11 It means to refer to Figure 4 Description of the non-magnetic metal cover for reference Fig.10 A diagram of an embodiment to which the described embodiment is applicable.

[0040] Fig.12 This is an enlarged cross-sectional view showing a part of a pump device according to still another embodiment.

[0041] Fig.13 It means to refer to Figure 5 The coil protection cover of the description is for reference Fig.12 A diagram of an embodiment to which the described embodiment is applicable.

[0042] Fig.14 This is an enlarged cross-sectional view showing a part of a pump device according to still another embodiment.

[0043] Fig.15 It means to refer to Figure 5 The coil protection cover of the description is for reference Fig.14 A diagram of an embodiment to which the described embodiment is applicable.

[0044] Fig.16 It is a diagram showing still another embodiment of the pump device.

[0045] Fig.17 It is a diagram showing still another embodiment of the pump device.

[0046] Fig.18 It is a diagram showing still another embodiment of the pump device.

[0047] Fig.19 It is a diagram showing still another embodiment of the pump device. DETAILED DESCRIPTION

[0048] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 1 is a cross-sectional view showing an embodiment of a pump device for transferring liquefied gas. Specific examples of liquefied gas include liquid hydrogen, liquefied natural gas, liquid oxygen, liquid nitrogen, and liquid ammonia.

[0049] like Figure 1 As shown, the pump device has: a pump 1 having an impeller 2; a rotating shaft 5 to which the impeller 2 is fixed; and a motor 7 for rotating the rotating shaft 5 and the impeller 2. The pump 1 has an impeller shell 15 that accommodates the impeller 2 inside. The impeller shell 15 has a suction port 16 and a discharge port (not shown) for liquefied gas. The liquid inlet 2a of the impeller 2 faces the suction port 16. Examples of the material of the impeller shell 15 include iron, cast iron, stainless steel, nickel alloy, etc. The suction port 16 of the pump 1 is directly or indirectly connected to a storage tank (not shown) for storing liquefied gas.

[0050] The pump device has bearings 31 and 32 that rotatably support the rotating shaft 5. The electric motor 7 has: a rotor assembly 21 that can rotate integrally with the rotating shaft 5; a motor stator 22 that surrounds the rotor assembly 21; and a motor housing 23 that holds the motor stator 22. The motor housing 23 forms a motor chamber 24 inside thereof, and the rotor assembly 21 and the motor stator 22 are arranged in the motor chamber 24. The motor stator 22 has: a plurality of coils 26 that are arranged in a manner surrounding the rotor assembly 21; and a stator core 27 that holds these coils 26. The motor stator 22 is in surface contact with the inner surface of the motor housing 23. The motor housing 23 is made of aluminum or an aluminum alloy.

[0051] The impeller shell 15 has a liquefied gas flow path 35 formed on the back side thereof. A portion of the liquefied gas pressurized by the rotation of the impeller 2 passes through the liquefied gas flow path 35 and is guided to the motor chamber 24. The liquefied gas in the motor chamber 24 cools the rotor assembly 21, the motor stator 22, and the bearings 31 and 32, and then passes through the return flow path 37 formed in the rotating shaft 5 and returns to the low-pressure side of the pump 1. In this way, a portion of the liquefied gas circulates between the pump 1 and the motor 7. The liquefied gas has electrical insulation properties, so even if the liquefied gas impregnates the coil 26, there will be no leakage.

[0052] The operation of the pump device is as follows. When the motor 7 rotates the rotating shaft 5 and the impeller 2, the liquefied gas flows into the impeller shell 15 through the suction port 16, and then flows into the impeller 2 through the liquid inlet 2a. The liquefied gas is pressurized as the impeller 2 rotates, and is discharged from the discharge port (not shown). A portion of the pressurized liquefied gas in the impeller shell 15 passes through the liquefied gas flow path 35 and moves into the motor chamber 24. The liquefied gas in the motor chamber 24 cools the rotor assembly 21, the motor stator 22, and the bearings 31 and 32, and then returns to the low-pressure side of the pump 1 through the return flow path 37.

[0053] Figure 2 Yes means Figure 1 An enlarged cross-sectional view of a portion of the pump assembly is shown. Figure 2 As shown, the rotor assembly 21 includes a motor rotor 40 fixed to the rotating shaft 5, side rings 41 disposed on both sides of the motor rotor 40, and a sealing cover 42 fixed to the outer circumference of the side ring 41. The side ring 41 is fixed to the outer circumference of the rotating shaft 5.

[0054] The motor 7 of the present embodiment is an induction motor, and therefore, the motor rotor 40 includes a plurality of rotor bars 44 arranged in the circumferential direction of the rotary shaft 5 and end rings 45 connected to both ends of the plurality of rotor bars 44 .

[0055] Figure 3 yes Figure 2 A cross-sectional view of the rotor assembly 21 is shown. Figure 3As shown, a plurality of rotor bars 44 are arranged in the circumferential direction of the rotating shaft 5. The motor rotor 40 has a rotor core 46 formed of a plurality of stacked electromagnetic steel plates, and the plurality of rotor bars 44 are arranged in the rotor core 46. The sealing cover 42 is in contact with the outer peripheral surface of the rotor core 46.

[0056] The materials of the rotor bars 44 and the end rings 45 are not particularly limited, but examples of the materials of the rotor bars 44 and the end rings 45 include aluminum (especially pure aluminum) and copper. In one embodiment, the rotor bars 44 and the end rings 45 are an integral structure manufactured by die casting.

[0057] The sealed cover 42 has a cylindrical shape and is made of glass fiber. The axial length of the sealed cover 42 is greater than the axial length of the motor rotor 40. The side ring 41 is arranged on the outer side of the end ring 45 in the axial direction of the rotating shaft 5. The side ring 41 is in contact with the end ring 45. In the present embodiment, the side ring 41 is also made of glass fiber. The sealed cover 42 is fixed to the side ring 41 by, for example, an adhesive. The sealed cover 42 and the side ring 41 are formed of the same material and have the same linear expansion coefficient. Therefore, when the sealed cover 42 and the side ring 41 are deformed due to temperature changes, no gap will be generated at the joint between the sealed cover 42 and the side ring 41.

[0058] The sealing cover 42 and the side ring 41 form a sealed space in which the motor rotor 40 is arranged. Therefore, the motor rotor 40 can be protected from the liquefied gas in the motor chamber 24 of the electric motor 7. In addition, the sealing cover 42 made of glass fiber can enhance the mechanical strength of the motor rotor 40. Therefore, when a large centrifugal force is applied to the motor rotor 40 rotating at an ultra-high speed, deformation and damage of the components constituting the motor rotor 40 can be prevented. In particular, if Figure 3 As shown in FIG. 1 , the rotor core bridge 46a of the rotor core 46 located radially outward of each rotor bar 44 is thin, and the core bridge 46a is easily deformed outward. The sealing cover 42 can prevent the rotor bar 44 and the core bridge 46a from deforming radially outward. In addition, no eddy current is generated in the sealing cover 42 made of glass fiber, so the sealing cover 42 does not impair the performance of the motor 7.

[0059] Figure 3 In the illustrated embodiment, the rotor core 46 is a closed type having rotor core connecting bridges 46 a on the radially outer sides of each rotor bar 44 , but in one embodiment, the rotor core 46 may be an open type without the rotor core connecting bridges 46 a .

[0060] The tensile strength of glass fiber is greater than the tensile strength of stainless steel used as a rotor sealing material of a conventional sealed motor. Therefore, the sealing cover 42 made of glass fiber can be made thinner. As a result, the magnetic gap of the motor 7 can be reduced, and high motor performance can be exerted.

[0061] The sealing cover 42 made of glass fiber is manufactured using a filament winding process. Specifically, the glass fiber is applied with tensile force and coated with an adhesive resin such as epoxy resin, and then the glass fiber is wound around the outer peripheral surface of the motor rotor 40. This type of glass fiber is also called glass fiber reinforced plastic. According to this process, the airtightness of the sealing cover 42 made of glass fiber can be improved.

[0062] In one embodiment, if Figure 2 As shown, the pump device may also include a balancing ring 51 disposed outside the side ring 41 in the axial direction of the rotating shaft 5. The balancing ring 51 is fixed to the outer peripheral surface of the rotating shaft 5. The balancing ring 51 is in contact with the sealing cover 42 and the side ring 41. The balancing ring 51 has an outer diameter that is the same as or larger than that of the sealing cover 42. When the sealing cover 42 is manufactured using a filament winding process, the balancing ring 51 functions as a winding tube. In addition, the balancing ring 51 is also used for the purpose of correcting the rotational balance of the motor rotor 40. The balancing ring 51 is made of a non-magnetic metal such as austenitic stainless steel.

[0063] Figure 4 FIG. 1 is an enlarged cross-sectional view showing a portion of a pump device according to another embodiment. Figures 1 to 3 The embodiments described are the same, so the repeated description is omitted. Figure 4 As shown, in this embodiment, the rotor assembly 21 further includes a non-magnetic metal cover 52 fixed to the outer peripheral surface of the balance ring 51. The non-magnetic metal cover 52 has a cylindrical shape and is arranged outside the sealing cover 42. The non-magnetic metal cover 52 is made of a non-magnetic metal such as austenitic stainless steel. The non-magnetic metal cover 52 is fixed to the balance ring 51 by welding.

[0064] The rotor assembly 21 of this embodiment has a double sealing structure that seals the motor rotor 40. That is, the sealing cover 42 and the side ring 41 form a first sealed space where the power supply rotor 40 is arranged, and the non-magnetic metal cover 52 and the balance ring 51 form a second sealed space where the sealing cover 42, the side ring 41, and the motor rotor 40 are arranged. The double sealing structure of this embodiment can reliably prevent the liquefied gas from contacting the motor rotor 40.

[0065] The sealing cover 42 made of glass fiber not only seals the motor rotor 40, but also can enhance the mechanical strength of the motor rotor 40. Therefore, the non-magnetic metal cover 52 only needs to have a thickness sufficient to seal the motor rotor 40, and the non-magnetic metal cover 52 can be thinner than the sealing cover 42. For example, the non-magnetic metal cover 52 can have a thickness of about 1 / 10 of the sealing cover 42.

[0066] Figure 5 FIG. 1 is an enlarged cross-sectional view showing a portion of a pump device according to another embodiment. Figures 1 to 3 The embodiments described are the same, so the repeated description is omitted. Figure 5 As shown, the pump device of this embodiment further includes a coil protection cover 55 disposed radially inward of the end of the coil 26. The coil protection cover 55 has a cylindrical shape. The coil protection cover 55 is made of a non-metallic material. As specific examples of the non-metallic material constituting the coil protection cover 55, ceramics and aramid fibers can be cited.

[0067] The coil 26 is in contact with the liquefied gas. The liquefied gas has electrical insulation properties, so there is no risk of leakage, but the high-speed airflow of the liquefied gas generated by the high-speed rotating rotor assembly 21 may come into contact with the coil 26. In particular, the coating (vernis) that fixes the wires of the coil 26 to each other and the enamel layer of the coil 26 are exposed to the liquefied gas and become brittle. There is a concern that the high-speed airflow of the liquefied gas may cause the coating and the enamel layer of the coil 26 to peel off, destroying the insulation between the coils 26.

[0068] According to the present embodiment, the coil protection cover 55 protects the end of the coil 26 from the high-speed gas flow of the liquefied gas, and can prevent the paint and the enamel layer of the coil 26 from peeling off. Figure 5 The coil protection cover 55 described above can also be applied to the Figure 4 The embodiments described above and the embodiments described below.

[0069] Figure 6 is an enlarged cross-sectional view showing a portion of a pump device according to another embodiment. Figure 7 yes Figure 6 The structure and operation of this embodiment not specifically described are similar to those of the reference Figures 1 to 3 The embodiment described is the same, so the repeated description is omitted. In this embodiment, the side ring 41, the sealing cover 42, and the non-magnetic metal cover 52 are not provided. The balance ring 51 is arranged outside the end ring 45 in the axial direction of the rotating shaft and contacts the end ring 45.

[0070] The rotor assembly 21 of the electric motor 7 includes a first reinforcement cover 57 surrounding the outer peripheral surface of the end ring 45 and a second reinforcement cover 58 surrounding the plurality of rotor bars 44. Figure 7 As shown, the plurality of rotor bars 44 are arranged along the circumferential direction of the rotating shaft 5. The first reinforcing cover 57 has a circular ring shape that contacts the outer peripheral surface of the end ring 45. The second reinforcing cover 58 has a cylindrical shape and contacts the outer peripheral surface of the rotor core 46. The second reinforcing cover 58 is arranged outside the plurality of rotor bars 44 in the radial direction of the motor rotor 40, and surrounds the plurality of rotor bars 44 and the rotor core 46 as a whole.

[0071] The first reinforcement cover 57 and the second reinforcement cover 58 are made of non-magnetic material. In the present embodiment, the first reinforcement cover 57 and the second reinforcement cover 58 are made of glass fiber. The first reinforcement cover 57 and the second reinforcement cover 58 of the present embodiment constitute an integral structure. The first reinforcement cover 57 is arranged on both sides of the second reinforcement cover 58. The first reinforcement cover 57 and the second reinforcement cover 58 made of glass fiber are manufactured using the above-mentioned filament winding process. When the first reinforcement cover 57 and the second reinforcement cover 58 are manufactured using the filament winding process, the balance ring 51 functions as a winding bobbin.

[0072] The thickness T1 of the first reinforcing cover 57 is greater than the thickness T2 of the second reinforcing cover 58 . Figure 6 In the illustrated embodiment, the outer diameter of the end ring 45 is smaller than the outer diameter of the rotor core 46. That is, the outer diameter of the first reinforcing cover 57 is the same as that of the second reinforcing cover 58, but the inner diameter of the first reinforcing cover 57 is smaller than that of the second reinforcing cover 58.

[0073] The balance ring 51 is located outside the first reinforcement cover 57 in the axial direction of the rotating shaft 5 and contacts the first reinforcement cover 57. Therefore, the balance ring 51 and the first reinforcement cover 57 and the second reinforcement cover 58, which are integral structures, form a space that completely seals the motor rotor 40, and can prevent the liquefied gas from contacting the motor rotor 40.

[0074] The first reinforcing cover 57 is provided to reinforce the end ring 45 disposed outside the rotor core 46. That is, the first reinforcing cover 57 can prevent the end ring 45 from being deformed radially outward due to the centrifugal force generated on the end ring 45 when the motor rotor 40 rotates at high speed.

[0075] The second reinforcing cover 58 is provided to reinforce the rotor core 46 and the rotor bars 44. That is, the second reinforcing cover 58 can prevent the rotor core 46 and the rotor bars 44 from being deformed radially outward due to the centrifugal force generated on the rotor core 46 and the rotor bars 44 when the motor rotor 40 rotates at a high speed. Figure 7As shown, the rotor core connecting bridges 46a of the rotor core 46 located radially outward of each rotor bar 44 are thin, and the core connecting bridges 46a are easily deformed outward. The second reinforcing cover 58 can prevent the rotor bars 44 and the core connecting bridges 46a from deforming radially outward.

[0076] Figure 7 In the illustrated embodiment, the rotor core 46 is a closed type having rotor core connecting bridges 46 a on the radially outer sides of each rotor bar 44 , but in one embodiment, the rotor core 46 may be an open type without the rotor core connecting bridges 46 a .

[0077] The rotor bars 44 are arranged inside the rotor core 46, whereas the end rings 45 are arranged outside the rotor core 46. Therefore, the end rings 45 are easily deformed outward due to centrifugal force. According to the present embodiment, the thickness T1 of the first reinforcement cover 57 is greater than the thickness T2 of the second reinforcement cover 58, so the first reinforcement cover 57 can prevent the deformation of the end rings 45. On this basis, the balance ring 51 in contact with the end rings 45 can prevent the deformation of the end rings 45 outward in the axial direction. Therefore, the structure of the present embodiment can prevent the radial and axial deformation of the end rings 45.

[0078] The first reinforcing cover 57 and the second reinforcing cover 58 can prevent deformation of the motor rotor 40 including the rotor bars 44 and the end rings 45, thereby preventing vibration of the motor rotor 40 during high-speed rotation and preventing the bearings 31 and 32 (see Figure 1 )’s lifespan is reduced.

[0079] The balance ring 51 is in contact with the end ring 45, and therefore also has the function of releasing the heat of the end ring 45. That is, the heat generated by the rotor bars 44 and the end ring 45 is transferred to the balance ring 51 made of non-magnetic metal, and released from the balance ring 51. The balance ring 51 is in contact with the liquefied gas, and therefore the heat is also transferred to the liquefied gas in the motor chamber 24. According to this embodiment, the motor rotor 40 including the rotor bars 44 and the end ring 45 can be prevented from overheating.

[0080] Figure 8 FIG. 1 is an enlarged cross-sectional view showing a portion of a pump device according to another embodiment. Figure 6 as well as Figure 7 The embodiments described are the same, so the repeated description thereof is omitted. The rotor assembly 21 of the motor 7 further includes a non-magnetic metal cover 52 fixed to the outer peripheral surface of the balance ring 51. The non-magnetic metal cover 52 has a cylindrical shape and contacts the outer peripheral surfaces of the first reinforcement cover 57 and the second reinforcement cover 58.

[0081] The non-magnetic metal cover 52 is arranged outside the first reinforcement cover 57 and the second reinforcement cover 58 in the radial direction of the motor rotor 40, and surrounds the entire first reinforcement cover 57 and the second reinforcement cover 58. The non-magnetic metal cover 52 is made of a non-magnetic metal such as austenitic stainless steel. The non-magnetic metal cover 52 is fixed to the balance ring 51 by welding.

[0082] The non-magnetic metal cover 52 and the balance ring 51 form a closed space in which the first reinforcement cover 57, the second reinforcement cover 58, and the motor rotor 40 are arranged. The structure of this embodiment can reliably prevent the liquefied gas from contacting the motor rotor 40. Figure 8 The described embodiment is suitable for the case where highly corrosive liquefied gas (liquid ammonia, etc.) is used.

[0083] Fig. 9 FIG. 1 is an enlarged cross-sectional view showing a portion of a pump device according to another embodiment. Figure 6 as well as Figure 7 The embodiments described are the same, and therefore, the repeated description thereof will be omitted. In this embodiment, the second reinforcing cover 58 is made of a non-magnetic metal, and the second reinforcing cover 58 is connected to the balance ring 51 .

[0084] The second reinforcing cover 58 surrounds the motor rotor 40 including the rotor bars 44 and the end rings 45, and the first reinforcing cover 57. The axial length of the second reinforcing cover 58 is greater than the axial length of the motor rotor 40, and the center of the second reinforcing cover 58 contacts the outer circumferential surface of the rotor core 46. The outer circumferential surface of the first reinforcing cover 57 contacts the inner circumferential surface of the second reinforcing cover 58. Figure 6 as well as Figure 7 Similar to the described embodiment, the second reinforcing cover 58 can prevent the rotor core 46 and the rotor bars 44 from being deformed radially outward due to the centrifugal force exerted on the rotor core 46 and the rotor bars 44 when the motor rotor 40 rotates at a high speed.

[0085] An example of the non-magnetic metal constituting the second reinforcing cover 58 is stainless steel (more specifically, austenitic stainless steel). Fig. 9 In the illustrated embodiment, both ends of the second reinforcing cover 58 are fixed to the outer peripheral surface of the balancing ring 51. The second reinforcing cover 58 and the balancing ring 51 are fixed by welding. Therefore, the second reinforcing cover 58 and the balancing ring 51 form a closed space therein. The motor rotor 40 including the rotor bars 44 and the end rings 45 and the first reinforcing cover 57 are arranged in the closed space formed by the second reinforcing cover 58 and the balancing ring 51.

[0086] The first reinforcing cover 57 and Figure 6 The embodiment shown is also made of glass fibers. Figure 6 Similarly to the embodiment described above, it is possible to prevent the end ring 45 from being deformed outward in the radial direction due to the centrifugal force generated on the end ring 45 when the motor rotor 40 rotates at a high speed.

[0087] According to this embodiment, the second reinforcing cover 58 and the balance ring 51 made of non-magnetic metal can reliably prevent the liquefied gas from contacting the motor rotor 40. Fig. 9 The described embodiment is suitable for the case where highly corrosive liquefied gas (liquid ammonia, etc.) is used.

[0088] Fig.10 FIG. 1 is an enlarged cross-sectional view showing a portion of a pump device according to another embodiment. Figures 1 to 3 The embodiments described are the same, so the repeated description thereof is omitted. The motor 7 of this embodiment is a permanent magnet type synchronous motor having a motor rotor 40, and the motor rotor 40 has a permanent magnet 70. That is, Fig.10 As shown, the rotor assembly 21 includes a plurality of permanent magnets 70 arranged in the circumferential direction of the rotating shaft 5 , and a rotor yoke 71 that holds the permanent magnets 70 . Fig.10 In FIG. 7 , only one permanent magnet 70 is depicted. The rotor yoke 71 is made of laminated electromagnetic steel plates or ferromagnetic metal.

[0089] The side rings 41 are arranged on both sides of the motor rotor 40, that is, on both sides of the permanent magnet 70. The side rings 41 are made of glass fiber. The glass fiber has a linear expansion coefficient close to that of the material constituting the rotor yoke 71, so it is difficult to generate stress when thermally deformed. The motor rotor 40 including the permanent magnet 70 is arranged in a closed space formed by the sealing cover 42 and the side rings 41. Therefore, liquefied gases such as liquid hydrogen will not come into contact with the motor rotor 40. In particular, rare earth magnets used in synchronous motors easily absorb hydrogen and are brittle to hydrogen. According to this embodiment, the sealing cover 42 and the side rings 41 can protect the permanent magnet 70 used in the motor rotor 40 from liquefied gases such as liquid hydrogen.

[0090] Magnetic paths are formed on both sides of the permanent magnet 70, and these magnetic paths pass through the side ring 41. With the discontinuity of the stator core 27 in the circumferential direction, ripples of the rotating magnetic field occur during the rotation of the rotor assembly 21. As a result, the magnetic field intensity on both sides of the permanent magnet 70 changes periodically. The side ring 41 of this embodiment is non-metallic and is composed of glass fiber as a non-magnetic material, so the periodic change of the magnetic field intensity does not generate eddy current in the side ring 41.

[0091] Fig.11 Is to refer to Figure 4 The non-magnetic metal cover 52 described above is Fig.10A diagram of an embodiment applicable to the embodiment described. Although not shown in the figure, it is also possible to refer to Figure 5 The coil protection cover 55 of the description is for reference Fig.10 The embodiments described are applicable. Figure 4 The non-magnetic metal cover 52 described above and the reference Figure 5 The coil protection cover 55 described in the drawings is shown in FIG. Fig.10 The described embodiments apply.

[0092] Fig.12 FIG. 1 is an enlarged cross-sectional view showing a portion of a pump device according to another embodiment. Figures 1 to 3 The described implementation modes are the same, and therefore, repeated descriptions thereof will be omitted.

[0093] The rotor assembly 21 includes a balancing ring 51 disposed on both sides of the motor rotor 40, a sealing cover 72 fixed to the outer peripheral surface of the balancing ring 51, and a cylindrical reinforcement cover 73 disposed on the outer peripheral surface of the sealing cover 72. The sealing cover 72 has a cylindrical shape. The sealing cover 72 is made of non-magnetic metal, and the cylindrical reinforcement cover 73 is made of glass fiber. The sealing cover 72 and the balancing ring 51 are made of non-magnetic metal such as austenitic stainless steel. The sealing cover 72 is fixed to the balancing ring 51 by welding.

[0094] The sealing cover 72 and the balance ring 51 form a sealed space in which the motor rotor 40 including the rotor bars 44, the end rings 45, and the rotor core 46 is arranged. Therefore, the motor rotor 40 can be protected from the liquefied gas existing in the motor chamber 24 of the electric motor 7. The cylindrical reinforcement cover 73 is arranged on the radial outer side of the motor rotor 40. The cylindrical reinforcement cover 73 made of glass fiber can strengthen the mechanical strength of the motor rotor 40. Therefore, when a large centrifugal force is applied to the motor rotor 40 rotating at an ultra-high speed, deformation and damage of each component constituting the motor rotor 40 can be prevented.

[0095] In this embodiment, the side ring 41 is not provided, and the end ring 45 is in contact with the balance ring 51 . Fig.12 In the illustrated embodiment, both ends of the cylindrical reinforcing cover 73 are located inside the balancing ring 51 in the axial direction of the rotating shaft 5. In other words, the cylindrical reinforcing cover 73 is not provided outside the balancing ring 51 in the radial direction. According to this configuration, the heat generated by the motor rotor 40 is transferred and released from the end ring 45, the balancing ring 51, and the sealing cover 72, which are made of metal.

[0096] In order to further improve the heat dissipation effect, Fig.12In the illustrated embodiment, both ends of the cylindrical reinforcing cover 73 are located inside the end ring 45 in the axial direction of the rotating shaft 5. In other words, the cylindrical reinforcing cover 73 is not provided outside the balance ring 51 and the end ring 45 in the radial direction. According to this configuration, the exposed area of ​​the sealing cover 72 made of non-magnetic metal is increased, and heat dissipation from the sealing cover 72 is promoted.

[0097] Fig.13 Is to refer to Figure 5 The coil protection cover 55 of the description is for reference Fig.12 A diagram of an embodiment to which the described embodiment is applicable.

[0098] Fig.14 FIG. 1 is an enlarged cross-sectional view showing a portion of a pump device according to another embodiment. Figure 1 as well as Fig.13 The embodiments described are the same, so the repeated description thereof is omitted. The motor 7 of this embodiment is a permanent magnet type synchronous motor having a motor rotor 40, and the motor rotor 40 has a permanent magnet 70. That is, Fig.14 As shown, the rotor assembly 21 includes a plurality of permanent magnets 70 arranged in the circumferential direction of the rotating shaft 5 , and a rotor yoke 71 that holds the permanent magnets 70 . Fig.14 In FIG. 7 , only one permanent magnet 70 is depicted. The rotor yoke 71 is made of laminated electromagnetic steel plates or ferromagnetic metal.

[0099] The side rings 41 are arranged on both sides of the motor rotor 40, that is, on both sides of the permanent magnet 70. The side rings 41 are made of glass fiber. Magnetic paths are formed on both sides of the permanent magnet 70, and these magnetic paths pass through the side rings 41. With the discontinuity of the stator core 27 in the circumferential direction, ripples of the rotating magnetic field occur, so that the magnetic field intensity on both sides of the permanent magnet 70 changes periodically. The side rings 41 of this embodiment are non-metallic and made of glass fiber as a non-magnetic material, so the periodic change of the magnetic field intensity does not generate eddy currents in the side rings 41.

[0100] Both ends of the cylindrical reinforcing cover 73 are located inside the side ring 41 in the axial direction of the rotating shaft 5. In other words, the cylindrical reinforcing cover 73 is not provided outside the balance ring 51 and the side ring 41 in the radial direction. According to this structure, the exposed area of ​​the sealing cover 72 made of non-magnetic metal is increased, and heat dissipation from the sealing cover 72 is promoted.

[0101] Fig.15 It means to refer to Figure 5 The coil protection cover 55 of the description is for reference Fig.14 A diagram of an embodiment to which the described embodiment is applicable.

[0102] Fig.16FIG. 2 is a diagram showing another embodiment of the pump device. The structure and operation of this embodiment not specifically described are similar to those of the reference Figure 1 as well as Figure 2 The described implementation modes are the same, and therefore, repeated descriptions thereof will be omitted. Fig.16 The pump device of the illustrated embodiment has a return line 75 disposed outside the motor housing 23 and the impeller shell 15, instead of the return flow path 37 in the rotating shaft 5. One end of the return line 75 is connected to the motor housing 23, and the other end of the return line 75 is connected to the suction side of the impeller shell 15. The suction side of the impeller shell 15 is located between the impeller 2 and the suction port 16.

[0103] A portion of the liquefied gas pressurized by the rotation of the impeller 2 is guided to the motor chamber 24 through the liquefied gas flow path 35. The liquefied gas in the motor chamber 24 cools the rotor assembly 21, the motor stator 22, and the bearings 31 and 32, and then returns to the low-pressure side of the pump 1 through the return line 75.

[0104] Fig.17 FIG. 2 is a diagram showing another embodiment of the pump device. The structure and operation of this embodiment not specifically described are similar to those of the reference Figures 1 to 3 The described implementation modes are the same, and therefore, repeated descriptions thereof will be omitted. Fig.17 The pump device of the illustrated embodiment includes a shaft sealing device 80 disposed between the impeller 2 and the motor 7. Examples of the shaft sealing device 80 include a labyrinth seal and a mechanical seal. Fig.17 In the embodiment shown, the shaft seal device 80 is arranged on the back side of the impeller 2, that is, between the impeller 2 and the bearing 31. In one embodiment, the shaft seal device 80 can also be arranged on the back side of the bearing 31, that is, between the bearing 31 and the motor 7.

[0105] In this embodiment, no Figure 1 The liquefied gas flow path 35 shown. The liquefied gas in the impeller housing 15 passes only through the shaft seal device 80. When and / or after the liquefied gas passes through the shaft seal device 80, the liquefied gas is gasified to form boil-off gas. Therefore, the motor chamber 24 in the motor housing 23 is filled with boil-off gas, and the rotor assembly 21 and the motor stator 22 of the motor 7 are exposed to the boil-off gas. The boil-off gas in the motor chamber 24 cools the rotor assembly 21, the motor stator 22, and the bearings 31 and 32.

[0106] Fig.18 yes Fig.17 A variation of the embodiment shown in FIG. Fig.18As shown, the motor housing 23 may also be connected to a storage tank (not shown) storing liquefied gas via an evaporation gas return line 82. One end of the evaporation gas return line 82 is connected to the motor housing 23, and the other end of the evaporation gas return line 82 is connected to the gas phase portion of the storage tank. The evaporation gas in the motor chamber 24 cools the rotor assembly 21, the motor stator 22, and the bearings 31 and 32, and then passes through the evaporation gas return line 82 and returns to the storage tank (not shown).

[0107] Fig.19 FIG. 2 is a diagram showing another embodiment of the pump device. The structure and operation of this embodiment not specifically described are similar to those of the reference Figures 1 to 3 The described implementation modes are the same, and therefore, repeated descriptions thereof will be omitted. Fig.19 The pump device of the illustrated embodiment further includes a suction container 90 surrounding the pump 1 , the rotating shaft 5 , and the motor 7 , and a liquefied gas discharge pipe 91 connected to a discharge port (not shown) of the pump 1 .

[0108] The suction container 90 is a fluid container into which the liquefied gas is introduced. More specifically, the suction container 90 has a suction port 94 connected to a storage tank (not shown) storing the liquefied gas. The liquefied gas is supplied from the storage tank to the suction container 90 and is introduced into the suction container 90 through the suction port 94. The pump 1 and the motor 7 are immersed in the liquefied gas in the suction container 90.

[0109] The liquefied gas discharge pipe 91 extends from the discharge port (not shown) of the pump 1 to the outside of the suction container 90. A part of the liquefied gas in the suction container 90 is vaporized by the heat generated by the motor 7 and the heat entering from the outside of the suction container 90 to form boil-off gas. The suction container 90 has a boil-off gas discharge port 96 for discharging boil-off gas generated therein. The boil-off gas discharge port 96 is connected to the boil-off gas return line 82. The boil-off gas is returned from the suction container 90 to the storage tank (not shown) through the boil-off gas discharge port 96 and the boil-off gas return line 82.

[0110] Include reference Figures 4 to 15 The above-mentioned embodiments including the embodiments described above can also be applied to the reference Figures 16 to 19 Furthermore, all the above-mentioned embodiments can be appropriately combined as long as they can be implemented. For example, Fig.18 The embodiment shown is similar to Fig.19 Combination of embodiments shown.

[0111] The above-mentioned embodiments are recorded for the purpose of enabling a person with common knowledge in the technical field to which the present invention belongs to implement the present invention. As long as a person skilled in the art can certainly think of various variations of the above-mentioned embodiments, the technical idea of ​​the present invention can also be applied to other embodiments. Therefore, the present invention is not limited to the embodiments that have been recorded, and can be interpreted within the maximum scope of the technical idea defined by the technical solution.

[0112] Industrial Applicability

[0113] The present invention can be used for a pump device for transferring extremely low-temperature liquefied gas such as liquid hydrogen and liquefied natural gas, and can be particularly used for a pump device having an electric motor as a driving source of the pump.

[0114] Description of Reference Numerals

[0115] 1 Pump

[0116] 2 Impeller

[0117] 2a Liquid inlet

[0118] 5 Rotation axis

[0119] 7 Electric Motor

[0120] 15 Impeller housing

[0121] 16 suction port

[0122] 21 Rotor assembly

[0123] 22 Motor stator

[0124] 23 Motor housing

[0125] 24 Motor room

[0126] 26 Coil

[0127] 27 Stator core

[0128] 31, 32 bearings

[0129] 35 Liquid gas flow path

[0130] 37 Return flow

[0131] 40 Motor rotor

[0132] 41 Side ring

[0133] 42 Sealed cover

[0134] 44 rotor bars

[0135] 45 End ring

[0136] 46 Rotor core

[0137] 51 Balance Ring

[0138] 52 Non-magnetic metal cover

[0139] 55 Coil protection cover

[0140] 57 No. 1 reinforcement cover

[0141] 58 2nd reinforcement cover

[0142] 70 Permanent magnet

[0143] 71 Rotor yoke

[0144] 72 Sealed cover

[0145] 73 Cylinder reinforcement cover

[0146] 75 Return line

[0147] 80 Shaft sealing device

[0148] 82 Boil-off gas return line

[0149] 90 suction container

[0150] 91 Liquefied gas discharge pipe

[0151] 94 Intake port

[0152] 96 Evaporative gas exhaust port.

Claims

1. A pump device for liquefied gas, in, have: A pump having an impeller; A rotating shaft to which the impeller is fixed; and an electric motor for rotating the rotating shaft and the impeller, The electric motor has: a rotor assembly capable of rotating integrally with the rotating shaft; and a motor stator having a coil and a stator core, the coil surrounding the rotor assembly, The rotor assembly comprises: a motor rotor fixed to the rotating shaft; Side rings arranged on both sides of the motor rotor; and a sealing cover fixed to the outer peripheral surface of the side ring, The sealing cover is made of glass fiber.

2. The pump device according to claim 1, in, The side rings are made of glass fiber.

3. The pump device according to claim 1, in, The pump device also has: A balancing ring disposed outside the side ring in the axial direction of the rotating shaft; and a non-magnetic metal cover fixed to the outer peripheral surface of the balance ring, The non-magnetic metal cover and the balance ring form a closed space for the sealing cover, the side ring, and the motor rotor to be arranged.

4. The pump device according to claim 1, in, The pump device further includes a coil protection cover disposed radially inward of an end portion of the coil, wherein the coil protection cover is made of a non-metallic material.

5. A pump device for liquefied gas, in, have: A pump having an impeller; A rotating shaft to which the impeller is fixed; and an electric motor for rotating the rotating shaft and the impeller, The electric motor has: a rotor assembly capable of rotating integrally with the rotating shaft; and a motor stator having a coil and a stator core, the coil surrounding the rotor assembly, The rotor assembly comprises: a motor rotor fixed to the rotating shaft; Balancing rings are arranged on both sides of the motor rotor; a sealing cover fixed to the outer peripheral surface of the balancing ring; and a cylindrical reinforcing cover disposed on the outer peripheral surface of the sealing cover, The sealing cover is made of non-magnetic metal. The cylindrical reinforcement cover is made of glass fiber.

6. The pump device according to claim 5, in, Both ends of the cylindrical reinforcement cover are located inside the balance ring in the axial direction of the rotating shaft.

7. The pump device according to claim 6, in, The motor rotor comprises: a plurality of rotor bars arranged along the circumferential direction of the rotating shaft; and end rings fixed to both ends of the plurality of rotor bars. Both ends of the cylindrical reinforcement cover are located inside the end ring in the axial direction of the rotating shaft.

8. The pump device according to claim 5, in, The pump device also has side rings arranged on both sides of the motor rotor. The motor rotor has a plurality of permanent magnets arranged along the circumferential direction of the rotating shaft. The side ring is made of non-metallic material.

9. The pump device according to claim 8, in, The side rings are made of glass fiber.

10. The pump device according to claim 5, in, The pump device further includes a coil protection cover disposed radially inward of an end portion of the coil, wherein the coil protection cover is made of a non-metallic material.

11. A pump device for liquefied gas, in, have: A pump having an impeller; A rotating shaft to which the impeller is fixed; and an induction motor for rotating the rotating shaft and the impeller, The induction motor has: a rotor assembly capable of rotating integrally with the rotating shaft; and a motor stator having a coil and a stator core, the coil surrounding the rotor assembly, The rotor assembly comprises: A motor rotor having a plurality of rotor bars arranged along the circumferential direction of the rotating shaft, and end rings connected to both ends of the plurality of rotor bars; a balancing ring in contact with the end ring; A first reinforcement cover surrounding the outer peripheral surface of the end ring; and A second reinforcement cover surrounds the plurality of rotor bars.

12. The pump device according to claim 11, in, The first reinforcing cover is made of glass fiber.

13. The pump device according to claim 11, in, The second reinforcing cover is made of glass fiber.

14. The pump device according to claim 11, in, The thickness of the first reinforcement cover is greater than the thickness of the second reinforcement cover.

15. The pump device according to claim 11, in, The second reinforcement cover is made of non-magnetic metal and is fixed to the balance ring.

Images