Electric Centrifugal Compressor

Abstract

To provide an electric centrifugal compressor which can simplify a component around a bearing.SOLUTION: An electric centrifugal compressor comprises: an electric motor including a rotating shaft; a first impeller arranged at one end side of the rotating shaft; a first bearing for rotatably supporting the rotating shaft in a position between the first impeller and the electric motor, and including a lubricant; and a first bearing housing for accommodating the first bearing. The first bearing housing includes a compressed gas supply hole for supplying a compressed gas from the outside of the first bearing housing in a clearance between a rotating body including the rotating shaft and the first bearing housing, and an outlet of the compressed gas supply hole is formed at an inner face of the first bearing housing, and located between the first impeller and the first bearing in an axial direction of the rotating shaft.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an electric centrifugal compressor. [Background technology]

[0002] Fuel cell vehicles, which generate electricity using fuel cells installed in the vehicle body and run on the power of electric motors, are sometimes equipped with electric centrifugal compressors, which improve the efficiency of the fuel cell by supplying compressed air to the fuel cell.

[0003] In this type of electric centrifugal compressor, since clean compressed air needs to be supplied to the fuel cell, oil-free air bearings are mainly used (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-155696 A Summary of the Invention [Problem to be solved by the invention]

[0005] When using an air bearing that does not contain lubricant as described in Patent Document 1, it is necessary to manage the air around the bearing using a dedicated air pump or the like, which complicates the configuration of the parts around the bearing, including the bearing housing, and tends to lead to high costs.

[0006] In view of the above circumstances, an object of at least one embodiment of the present disclosure is to provide an electric centrifugal compressor that enables simplification of parts around a bearing. [Means for solving the problem]

[0007] An electric centrifugal compressor according to an embodiment of the present disclosure includes: an electric motor including a rotating shaft; A first impeller provided on one end side of the rotating shaft; a first bearing that rotatably supports the rotating shaft at a position between the first impeller and the electric motor and contains a lubricant; a first bearing housing that accommodates the first bearing; Equipped with the first bearing housing includes a compressed gas supply hole for supplying compressed gas from outside the first bearing housing to a gap between the first bearing housing and a rotating body including the rotating shaft, The outlet of the compressed gas supply hole is provided on the inner surface of the first bearing housing and is located between the first impeller and the first bearing in the axial direction of the rotating shaft. Effect of the Invention

[0008] According to at least one embodiment of the present disclosure, there is provided an electric centrifugal compressor that enables simplification of parts around a bearing. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view illustrating a schematic configuration of an electric centrifugal compressor 1 according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a cross-sectional view of the electric centrifugal compressor 1 shown in FIG. 1 at a circumferential position different from that of the cross-sectional view shown in FIG. [Diagram 3] 3 is an enlarged view of the vicinity of a high-pressure stage sleeve 18B in the cross section shown in FIG. 2. FIG. [Figure 4] FIG. 4 is a diagram showing a schematic cross section taken along line AA in FIG. [Diagram 5] 3 is an enlarged view of the vicinity of a low-pressure stage sleeve 18A in the cross section shown in FIG. 2. FIG. [Figure 6] FIG. 2 is an enlarged view of the vicinity of a high-pressure stage sleeve 18B of the electric centrifugal compressor 1 according to one embodiment, and shows a schematic cross section taken along the rotation axis CA of the electric centrifugal compressor 1. [Figure 7] 7 is a schematic cross-sectional view illustrating a state in which the rotation speed of a rotating shaft 3 in the electric centrifugal compressor 1 illustrated in FIG. 6 has exceeded a reference value. [Figure 8]FIG. 2 is an enlarged view of the vicinity of a high-pressure stage sleeve 18B of the electric centrifugal compressor 1 according to one embodiment, and shows a schematic cross section taken along the rotation axis CA of the electric centrifugal compressor 1. [Figure 9] 9 is a schematic cross-sectional view illustrating a state in which the rotation speed of a rotating shaft 3 in the electric centrifugal compressor 1 illustrated in FIG. 8 has exceeded a reference value. [Figure 10] 1 is a cross-sectional view showing a schematic configuration of an electric centrifugal compressor 1 equipped with a negative pressure pump 230. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure. For example, expressions expressing relative or absolute configuration, such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial," not only strictly express such a configuration, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions indicating that things are in an equal state, such as "identical," "equal," and "homogeneous," not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only refer to rectangular shapes, cylindrical shapes, etc. in the strict geometric sense, but also refer to shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect is obtained. On the other hand, the expressions "comprise", "include", or "have" a certain element are not exclusive expressions excluding the presence of other elements. In addition, the same components are denoted by the same reference numerals and the description thereof may be omitted.

[0011] (Multi-stage electric centrifugal compressor) 1 is a schematic diagram illustrating an electric centrifugal compressor 1 according to an embodiment of the present disclosure. In FIG. 1, a cross section of the electric centrifugal compressor 1 taken along a rotation axis CA of a rotating shaft 3 is illustrated. As shown in FIG. 1, an electric centrifugal compressor 1 according to some embodiments of the present disclosure is a multi-stage electric centrifugal compressor configured to drive impellers (a low-pressure stage impeller 4, a high-pressure stage impeller 5) provided at both ends of a rotating shaft 3 by an electric motor 10.

[0012] The exemplary electric centrifugal compressor 1 shown in FIG. 1 includes a low-pressure stage impeller 4, a high-pressure stage impeller 5, a low-pressure stage housing 6, a high-pressure stage housing 7, connecting piping 8, an electric motor 10, a low-pressure stage side bearing 15A, a high-pressure stage side bearing 15B, a low-pressure stage side bearing housing 16A, and a high-pressure stage side bearing housing 16B.

[0013] 1, the direction in which the rotation axis CA of the rotating shaft 3 extends is defined as the axial direction X, and the direction perpendicular to the rotation axis CA is defined as the radial direction Y. In the axial direction X, the side where the low-pressure stage impeller 4 is located relative to the high-pressure stage impeller 5 (the right side in FIG. 1) is defined as the low-pressure stage side XL, and the side opposite to the low-pressure stage side XL (the left side in FIG. 1) is defined as the high-pressure stage side XH.

[0014] (Electric motor) The electric motor 10 mounted on the electric centrifugal compressor 1 includes a rotor 11, a motor stator 12, and a stator housing 17 configured to accommodate the motor stator 12. The rotor 11 includes a rotating shaft 3 and a rotor assembly 13 attached to the outer periphery of the rotating shaft 3. The rotor assembly 13 includes a permanent magnet 14. The motor stator 12 is disposed so as to surround the outer periphery of the rotor assembly 13, and is supported by the stator housing 17 inside the stator housing 17. The motor stator 12 includes a motor coil (stator coil) 121, and is configured to generate a magnetic field that rotates the rotor 11 on which the permanent magnet 14 is mounted, by power supplied from a power source (not shown). When the rotor 11 rotates due to the magnetic field generated by the motor stator 12 (power generated by the electric motor 10), the impellers (low-pressure stage impeller 4 and high-pressure stage impeller 5) attached to the rotating shaft 3 rotate in conjunction with the rotor 11.

[0015] The electric centrifugal compressor 1 rotates the low-pressure stage impeller 4 to compress the gas introduced into the low-pressure stage housing 6 and pressurize the gas to a first pressure. The compressed gas pressurized to the first pressure is led into the high-pressure stage housing 7 through a connecting pipe 8. The electric centrifugal compressor 1 rotates the high-pressure stage impeller 5 to further compress the compressed gas introduced into the high-pressure stage housing 7 and pressurize the compressed gas to a second pressure higher than the first pressure.

[0016] (Low pressure stage housing, low pressure stage impeller) 1, the low-pressure stage housing 6 is formed with a low-pressure stage inlet opening 61 for introducing gas from the outside of the low-pressure stage housing 6 to the inside, and a low-pressure stage outlet opening 62 for discharging gas from the inside of the low-pressure stage housing 6 to the outside. Inside the low-pressure stage housing 6, a supply passage 63 for guiding the gas introduced into the inside of the low-pressure stage housing 6 from the low-pressure stage inlet opening 61 to the low-pressure stage impeller 4, and a scroll passage 64 for guiding the gas that has passed through the low-pressure stage impeller 4 to the low-pressure stage outlet opening 62 are formed. In the illustrated embodiment, the low-pressure stage inlet opening 61 opens toward the low-pressure stage side XL in the axial direction X. The low-pressure stage outlet opening 62 opens toward a direction intersecting (for example, perpendicular to) the rotation axis CA.

[0017] In the embodiment shown in FIG. 1, the low-pressure stage impeller 4 is provided on one end side of the rotating shaft 3. The low-pressure stage impeller 4 has a hub 41 mechanically connected to one end side of the rotating shaft 3, and a plurality of impeller blades 43 provided on the outer circumferential surface of the hub 41. The low-pressure stage impeller 4 can rotate integrally with the rotating shaft 3 about the rotation axis CA of the rotating shaft 3. The low-pressure stage impeller 4 is a centrifugal impeller configured to guide gas sent from the low-pressure stage side XL along the axial direction X to the outside in the radial direction Y. A gap (clearance) is formed between each of the tips of the plurality of impeller blades 43 and the convexly curved shroud surface of the low-pressure stage housing 6.

[0018] 1, the low-pressure stage housing 6 is combined with other members (in the illustrated example, the low-pressure stage bearing housing 16A) to form a low-pressure stage impeller chamber 66 that rotatably houses the low-pressure stage impeller 4. The low-pressure stage impeller chamber 66 communicates with a supply passage 63 located upstream in the gas flow direction, and a scroll passage 64 located downstream in the gas flow direction. The scroll passage 64 has a spiral shape that surrounds the outside of the low-pressure stage impeller 4 in the radial direction Y.

[0019] Gas (e.g., air) introduced into the supply passage 63 from the outside of the low-pressure stage housing 6 through the low-pressure stage inlet opening 61 flows through the supply passage 63 to the high-pressure stage side XH, and is then sent to the low-pressure stage impeller 4, where it is compressed by the rotation of the low-pressure stage impeller 4 and pressurized to a first pressure. The compressed gas (e.g., compressed air) that has passed through the low-pressure stage impeller 4 flows through the scroll passage 64 toward the outside in the radial direction Y, and is then discharged from the low-pressure stage housing 6 through the low-pressure stage outlet opening 62.

[0020] (High pressure stage housing, high pressure stage impeller) 1, the high-pressure stage housing 7 is formed with a high-pressure stage inlet opening 71 for introducing gas from the outside of the high-pressure stage housing 7 to the inside, and a high-pressure stage outlet opening 72 for discharging gas from the inside of the high-pressure stage housing 7 to the outside. Formed inside the high-pressure stage housing 7 are a supply passage 73 for guiding the gas introduced from the high-pressure stage inlet opening 71 into the inside of the high-pressure stage housing 7 to the high-pressure stage impeller 5, and a scroll passage 74 for guiding the gas that has passed through the high-pressure stage impeller 5 to the high-pressure stage outlet opening 72. In the illustrated embodiment, each of the high-pressure stage inlet opening 71 and the high-pressure stage outlet opening 72 opens in a direction intersecting (for example, perpendicular to) the rotation axis CA.

[0021] In the embodiment shown in FIG. 1, the high-pressure stage impeller 5 is provided on the other end side of the rotating shaft 3. The high-pressure stage impeller 5 has a hub 51 mechanically connected to the other end side of the rotating shaft 3, and a plurality of impeller blades 53 provided on the outer circumferential surface of the hub 51. The high-pressure stage impeller 5 can rotate integrally with the rotating shaft 3 about the rotation axis CA of the rotating shaft 3. The high-pressure stage impeller 5 is a centrifugal impeller configured to guide gas sent from the high-pressure stage side XH along the axial direction X to the outside in the radial direction Y. A gap (clearance) is formed between each of the tips of the plurality of impeller blades 53 and the convexly curved shroud surface of the high-pressure stage housing 7.

[0022] 1, the high-pressure stage housing 7 is combined with other members (in the illustrated example, the high-pressure stage bearing housing 16B) to form a high-pressure stage impeller chamber 76 that rotatably houses the high-pressure stage impeller 5. The high-pressure stage impeller chamber 76 communicates with a supply passage 73 located upstream in the gas flow direction, and a scroll passage 74 located downstream in the gas flow direction. The scroll passage 74 has a spiral shape that surrounds the outside of the high-pressure stage impeller 5 in the radial direction Y.

[0023] (Connecting piping) As shown in Fig. 1, the electric centrifugal compressor 1 includes a connecting pipe 8 for supplying compressed gas compressed by the low-pressure stage impeller 4 to the high-pressure stage housing 7. As shown in Fig. 1, the connecting pipe 8 is formed in a tubular shape extending along its length direction, and includes at least a high-pressure stage side connecting part 81 connected to the above-mentioned high-pressure stage inlet opening 71, and a low-pressure stage side connecting part 82 connected to the low-pressure stage outlet opening 62. In the illustrated embodiment, each of the high-pressure stage side connecting part 81 and the low-pressure stage side connecting part 82 extends along a direction intersecting (orthogonal in the illustrated example) the rotation axis CA of the rotating shaft 3.

[0024] The connecting pipe 8 further includes an intermediate portion 83 extending along the rotation axis CA of the rotating shaft, a low-pressure stage side curved portion 84 having a curved shape connecting the low-pressure stage side connecting portion 82 and the intermediate portion 83, and a high-pressure stage side curved portion 85 having a curved shape connecting the high-pressure stage side connecting portion 81 and the intermediate portion 83. In Fig. 1, the boundaries between the respective portions of the connecting pipe 8 are indicated by two-dot chain lines. The respective portions of the connecting pipe 8 may be constituted by separate members, or may be integrally formed from a single material.

[0025] The compressed gas discharged from the low-pressure stage outlet opening 62 of the low-pressure stage housing 6 flows through the connecting pipe 8 from the low-pressure stage side connecting portion 82 toward the high-pressure stage side connecting portion 81, and then is guided to the supply passage 73 through the high-pressure stage inlet opening 71 of the high-pressure stage housing 7. The compressed gas guided to the supply passage 73 is sent to the high-pressure stage impeller 5, and compressed by the rotation of the high-pressure stage impeller 5, and pressurized to a second pressure higher than the first pressure. The compressed gas that has passed through the high-pressure stage impeller 5 flows through the scroll passage 74 toward the outside in the radial direction Y, and then is discharged from the high-pressure stage housing 7 through the high-pressure stage outlet opening 72.

[0026] In the illustrated embodiment, the electric centrifugal compressor 1 is an electric centrifugal compressor for a fuel cell vehicle. Therefore, the compressed gas compressed by the high-pressure stage impeller 5 is supplied to an air electrode of a fuel cell (not shown). Note that the present disclosure may be applied to electric centrifugal compressors other than those for fuel cell vehicles, for example, electric centrifugal compressors for internal combustion engines that pressurize combustion gas sent to an internal combustion engine such as an engine.

[0027] According to the above configuration, the high-pressure stage housing 7 has a high-pressure stage inlet opening 71 opening in a direction intersecting the rotation axis CA of the rotating shaft 3, and the high-pressure stage side connection part 81 of the connecting pipe 8 is connected to the high-pressure stage inlet opening 71. Therefore, the compressed gas compressed by the low-pressure stage impeller 4 is supplied to the inside of the high-pressure stage housing 7 from the outer periphery side (outside in the radial direction Y) of the high-pressure stage housing 7 through the connecting pipe 8. In this case, the length of the connecting pipe 8 and the high-pressure stage housing 7 in the axial direction X can be made shorter than when the compressed gas is introduced into the high-pressure stage housing 7 along the axial direction X of the rotating shaft 3. This allows the length of the electric centrifugal compressor 1 in the axial direction X to be shortened, thereby making it possible to reduce the size and weight of the multi-stage electric centrifugal compressor. In addition, according to the electric centrifugal compressor 1, a high pressure ratio can be achieved at a low flow rate, and a multi-stage electric centrifugal compressor with excellent thrust load balance can be realized.

[0028] (Bearings) The low-pressure stage bearing 15A rotatably supports the rotating shaft 3 at a position between the low-pressure stage impeller 4 and the electric motor 10 (between the low-pressure stage impeller 4 and the rotor assembly 13). The low-pressure stage bearing 15A is a grease-filled ball bearing that is filled with grease as a lubricant in advance. Compared to air bearings, ball bearings do not require idling, do not require complex systems, are highly marketable, and have excellent durability against repeated rotation and stopping of the rotating shaft 3.

[0029] The high-pressure stage bearing 15B rotatably supports the rotating shaft 3 at a position between the high-pressure stage impeller 5 and the electric motor 10 (between the high-pressure stage impeller 5 and the rotor assembly 13). The high-pressure stage bearing 15B is a grease-filled ball bearing in which grease is filled in advance as a lubricant.

[0030] According to the above configuration, since it is not necessary to supply grease to the low-pressure stage bearing 15A, the structure of the parts around the low-pressure stage bearing 15A (for example, the low-pressure stage bearing housing 16A) can be simplified, and the multi-stage electric centrifugal compressor can be made smaller and lighter. Also, since it is not necessary to supply grease to the high-pressure stage bearing 15B, the structure of the parts around the high-pressure stage bearing 15B (for example, the high-pressure stage bearing housing 16B) can be simplified, and the multi-stage electric centrifugal compressor can be made smaller and lighter.

[0031] (Bearing housing) The low-pressure stage bearing housing 16A accommodates the low-pressure stage bearing 15A, and the low-pressure stage bearing 15A is supported by a bearing support surface 161 formed inside the low-pressure stage bearing housing 16A. The high-pressure stage bearing housing 16B accommodates the high-pressure stage bearing 15B, and the high-pressure stage bearing 15B is supported by a bearing support surface 162 formed inside the high-pressure stage bearing housing 16B.

[0032] The low-pressure stage side bearing housing 16A, the high-pressure stage side bearing housing 16B, and the stator housing 17 are disposed between the low-pressure stage housing 6 and the high-pressure stage housing 7 in the axial direction X. The stator housing 17 is located between the low-pressure stage side bearing housing 16A and the high-pressure stage side bearing housing 16B in the axial direction X, and is adjacent to each of the low-pressure stage side bearing housing 16A and the high-pressure stage side bearing housing 16B.

[0033] The low-pressure stage bearing housing 16A is disposed on the high-pressure stage side XH of the low-pressure stage housing 6 and on the low-pressure stage side XL of the stator housing 17. The low-pressure stage bearing housing 16A is mechanically connected to the low-pressure stage housing 6 and the stator housing 17 arranged adjacent to the low-pressure stage bearing housing 16A in the axial direction X by fastening members such as fastening bolts. The high-pressure stage bearing housing 16B is disposed on the low-pressure stage side XL of the high-pressure stage housing 7 and on the high-pressure stage side XH of the stator housing 17. The high-pressure stage bearing housing 16B is mechanically connected to the high-pressure stage housing 7 and the stator housing 17 arranged adjacent to the high-pressure stage bearing housing 16B in the axial direction X by fastening members such as fastening bolts. Further detailed configurations of the low-pressure stage bearing housing 16A and the high-pressure stage bearing housing 16B will be described later.

[0034] (sleeve) In the illustrated embodiment, the electric centrifugal compressor 1 further includes a low-pressure stage sleeve 18A attached to the outer periphery of the rotating shaft 3 between the low-pressure stage impeller 4 and the low-pressure stage bearing 15A in the axial direction X, a high-pressure stage sleeve 18B attached to the outer periphery of the rotating shaft 3 between the high-pressure stage impeller 5 and the high-pressure stage bearing 15B in the axial direction X, and a pressure spring 19 that biases the high-pressure stage bearing 15B toward the low-pressure stage side XL. The above-mentioned rotating body 11 further includes the low-pressure stage sleeve 18A and the high-pressure stage sleeve 18B.

[0035] The low-pressure stage bearing housing 16A has an inner surface (sleeve-opposing surface) 36 facing the outer circumferential surface 34 of the low-pressure stage sleeve 18A, and a locking surface 164 that extends from the end of the bearing support surface 161 on the low-pressure stage side XL toward the inside in the radial direction and engages with the low-pressure stage bearing 15A. The inner surface 36 is formed to have a smaller diameter than the bearing support surface 161. The high-pressure stage bearing housing 16B has an inner surface (sleeve-opposing surface) 165 facing the outer circumferential surface 181 of the high-pressure stage sleeve 18B, and a locking surface 166 that extends from the end of the bearing support surface 162 on the high-pressure stage side XH toward the inside in the radial direction. The inner surface 165 is formed to have a smaller diameter than the bearing support surface 162. The above-mentioned pressure spring 19 is disposed between the locking surface 166 and the high-pressure stage bearing 15B, and applies a predetermined pressure to the high-pressure stage bearing 15B.

[0036] Fig. 2 is a diagram showing a cross section of the electric centrifugal compressor 1 shown in Fig. 1 at a different circumferential position from the cross section shown in Fig. 1. The cross section shown in Fig. 2 is also a cross section along the rotation axis CA. Fig. 3 is an enlarged view of the vicinity of the high-pressure stage sleeve 18B in the cross section shown in Fig. 2. Fig. 4 is a diagram showing a schematic view of the AA cross section in Fig. 3. Fig. 5 is an enlarged view of the vicinity of the low-pressure stage sleeve 18A in the cross section shown in Fig. 2.

[0037] (Compressed air supply port on the high pressure stage side) As shown in FIG. 2 or 3, the high-pressure stage bearing housing 16B includes a compressed air supply hole 90 for supplying compressed air to a gap 25 (in the illustrated example, a gap between an outer peripheral surface 181 of the high-pressure stage sleeve 18B and an inner surface 165 of the high-pressure stage bearing housing 16B) between the rotor 11 including the rotating shaft 3 and the high-pressure stage bearing housing 16B. The compressed air supply hole 90 is formed as a through hole that penetrates the high-pressure stage bearing housing 16B in the radial direction from the outer surface 168 to the inner surface 165 of the high-pressure stage bearing housing 16B. An inlet 90a of the compressed air supply hole 90 is formed on the outer surface 168 of the high-pressure stage bearing housing 16B, and an outlet 90b of the compressed air supply hole 90 is formed on the inner surface 165 of the high-pressure stage bearing housing 16B. The outlet 90b of the compressed air supply hole 90 is located between the high-pressure stage impeller 5 and the high-pressure stage bearing 15B in the axial direction.

[0038] As shown in FIG. 2, the above-described electric centrifugal compressor 1 includes a compressed air inlet line 26 configured to introduce compressed air from a pressure source (e.g., the compressed air supply line 21 or the surge tank 27) to the inlet 90a of the compressed air supply hole 90.

[0039] The compressed air introduction line 26 is configured to introduce compressed air from each of the compressed air supply line 21 and the surge tank 27 to the inlet 90a of the compressed air supply hole 90. The gas in the surge tank 27 is made higher in pressure than a space 24 described below by a compressor 28. The compressed air introduction line 26 includes a first pipe 261 having one side connected to the branching portion 211 of the compressed air supply line 21 and the other side connected to the inlet 90a, a second pipe 262 having one side connected to the first pipe 261 and the other side connected to the surge tank 27, and a switching device 263 configured to be able to switch the supply source of compressed air to the inlet 90a between the compressed air supply line 21 and the surge tank 27. In addition, a cooling device 265 for cooling the compressed air is provided on the compressed air supply line 21. In another embodiment, the cooling device 265 may be provided on the first piping 261 upstream of the switching device 263 (between the branching portion 211 and the switching device 263 in the first piping 261).

[0040] 2, the switching device 263 may be a three-way valve provided at the connection between the first pipe 261 and the second pipe 262, or may be a valve (for example, an on-off valve) provided upstream of the connection between the first pipe 261 and the second pipe 262 and in the second pipe 262. In some other embodiments, the compressed air introduction line 26 may include a pipe connected at one side to the surge tank 27 and connected at the other side to the inlet 90a, and may be configured to introduce compressed air only from the surge tank 27 to the inlet 90a. By configuring the compressed air to be able to be supplied from the compressed air supply line 21 to the inlet 90a, the capacity of the surge tank 27 can be made small.

[0041] 3, a space 24 is formed between the back surface 57 of the high-pressure stage impeller 5 and the high-pressure stage side surface 167 of the high-pressure stage side bearing housing 16B facing the back surface 57. In addition, a gap 25 formed between the outer peripheral surface 181 of the high-pressure stage side sleeve 18B and the inner surface 165 of the high-pressure stage side bearing housing 16B communicates with the space 24.

[0042] In the illustrated embodiment, as shown in FIG. 3, an annular groove 182 into which a seal member (e.g., an annular seal ring) 86 fits, an annular groove 183 into which a seal member (e.g., an annular seal ring) 87 fits, and an annular groove 184 into which a seal member (e.g., an annular seal ring) 88 fits are formed on the outer peripheral surface 181 of the high-pressure stage sleeve 18B.

[0043] The annular groove 182 is located between the high pressure stage impeller 5 and the outlet 90b of the compressed air supply hole 90 in the axial direction X. The seal member 86 is provided so as to seal the gap 25 at a position between the high pressure stage impeller 5 and the outlet 90b of the compressed air supply hole 90 in the axial direction X.

[0044] The annular groove 183 is located between the outlet 90b of the compressed air supply hole 90 and the high-pressure stage side bearing 15B in the axial direction. Therefore, the outlet 90b of the compressed air supply hole 90 is located between the annular groove 182 and the annular groove 183 in the axial direction X. The seal member 87 is provided so as to seal the gap 25 at a position between the outlet 90b of the compressed air supply hole 90 and the high-pressure stage side bearing 15B in the axial direction.

[0045] The annular groove 184 is located between the outlet 90b of the compressed air supply hole 90 and the high-pressure stage side bearing 15B in the axial direction (more specifically, between the annular groove 183 and the high-pressure stage side bearing 15B in the axial direction). The seal member 88 is provided so as to seal the gap 25 at a position between the outlet of the compressed air supply hole 90 and the high-pressure stage side bearing 15B in the axial direction (more specifically, between the annular groove 183 and the high-pressure stage side bearing 15B in the axial direction). The outer surface of each of the seal members 86, 87 and 88 abuts against the outer peripheral surface 181 of the high-pressure stage side sleeve 18B, dividing the gap 25 into a plurality of parts.

[0046] When the high-pressure stage impeller 5 rotates, the temperature and pressure of the gas present in the space 24 increases. If the gas present in the space 24 passes through the gap 25 and flows into the high-pressure stage side bearing 15B, the grease in the high-pressure stage side bearing 15B may turn into oil mist, causing deterioration of the high-pressure stage side bearing 15B.

[0047] In this regard, according to the above configuration, the high pressure stage side bearing housing 16B includes a compressed air supply hole 90 for supplying compressed gas from outside the high pressure stage side bearing housing 16B to the gap 25 between the rotating body 11 including the rotating shaft 3 and the high pressure stage side bearing housing 16B, and the outlet 90b of the compressed air supply hole 90 is formed on the inner surface 165 of the high pressure stage side bearing housing 16B and is located between the high pressure stage impeller 5 and the high pressure stage side bearing 15B in the axial direction X.

[0048] As a result, compressed gas is supplied to the gap 25 from the compressed air supply hole 90, so that leakage flow from the space 24 facing the back surface 57 of the high-pressure stage impeller 5 to the high-pressure stage side bearing 15B can be suppressed. This makes it possible to suppress the grease of the high-pressure stage side bearing 15B from turning into oil mist due to the leakage flow, and to realize improved durability and a longer lifespan of the high-pressure stage side bearing 15B.

[0049] Furthermore, by supplying compressed air from the compressed air inlet line 26 to the inlet 90a of the compressed air supply hole 90 so that the pressure in the space 89 between the sealing members 86 and 87 within the gap 25 becomes greater than the pressure in the space 24 adjacent to the back surface of the high-pressure stage impeller 5, leakage flow from the space 24 facing the back surface 57 of the high-pressure stage impeller 5 to the high-pressure stage side bearing 15B can be effectively suppressed.

[0050] Furthermore, compressed air is supplied from the compressed air introduction line 26 to the inlet 90a of the compressed air supply hole 90 so that the pressure in the space 89 between the seal member 86 and the seal member 87 in the gap 25 becomes greater than the pressure in the space 79 (the space between the seal member 88 and the high-pressure stage bearing 15B) in the gap 25 that accommodates the high-pressure stage bearing 15B, thereby preventing the grease sealed in the high-pressure stage bearing 15B from leaking out into the flow path in the high-pressure stage housing 7 through the gap 25 or the space 24. This prevents the grease from being mixed into the compressed gas compressed by the electric centrifugal compressor 1, so that the electric centrifugal compressor 1 can supply clean compressed gas to a fuel cell or the like.

[0051] (Purge hole on the high pressure stage side) As shown in FIG. 2 or FIG. 3, the high-pressure stage bearing housing 16B includes a purge hole 92 (purge passage) for discharging the compressed air supplied from the compressed air supply hole 90 to the gap 25 from the gap 25 to the outside of the high-pressure stage bearing housing 16B. The purge hole 92 is formed as a through hole that penetrates the high-pressure stage bearing housing 16B in the radial direction from the outer surface 168 to the inner surface 165 of the high-pressure stage bearing housing 16B. An inlet 92a of the purge hole 92 is formed on the inner surface 165 of the high-pressure stage bearing housing 16B and is located between the high-pressure stage impeller 5 and the high-pressure stage bearing 15B in the axial direction X. In the example shown in FIG. 3, the inlet 92a of the purge hole 92 is formed on the high-pressure stage impeller 5 side of the bearing support surface 162 and opens toward the space 99 in which the pressure spring 19 is accommodated. An outlet 92b of the purge hole 92 is formed on the outer surface 168 of the high-pressure stage bearing housing 16B.

[0052] According to the above configuration, the compressed air supplied to the gap 25 is discharged to the outside of the high-pressure stage side bearing housing 16B through the purge hole 92, so that it is possible to prevent the compressed air supplied to the gap 25 from entering the inside of the high-pressure stage side bearing 15B. This makes it possible to prevent the grease of the high-pressure stage side bearing 15B from turning into oil mist, thereby achieving improved durability and a longer lifespan of the high-pressure stage side bearing 15B.

[0053] As shown in Fig. 3 or 4, the high-pressure stage bearing 15B includes an inner ring 94, an outer ring 95, a plurality of balls 96 (a plurality of rolling elements) held between the inner ring 94 and the outer ring 95, and a pair of annular seal plates 97 positioned on both sides of the balls 96 in the axial direction X and held by the outer ring 95. Here, an annular gap formed between the annular seal plate 97 on the high-pressure stage impeller 5 side of the pair of annular seal plates 97 and the inner ring 94 is defined as a seal plate gap 98, and a cross-sectional area perpendicular to the axial direction X in the seal plate gap 98 (the area of ​​the annular seal plate gap 98 shown in Fig. 4) is defined as S1. The purge hole 92 has a passage cross-sectional area S2 larger than the cross-sectional area S1. The purge hole 92 may have a passage cross-sectional area S2 larger than the cross-sectional area S1 from the inlet 92a to the outlet 92b. The passage cross-sectional area of ​​the purge hole 92 means the cross-sectional area perpendicular to the flow direction of the compressed air in the purge hole 92 (the cross-sectional area perpendicular to the extension direction of the purge hole 92).

[0054] In this way, the purge hole 92 has a passage cross-sectional area S2 larger than the cross-sectional area S1 of the seal plate gap 98, which promotes the flow of compressed air supplied to the gap 25 into the purge hole 92 and suppresses the intrusion of compressed air into the high-pressure stage side bearing 15B from the gap 25. This suppresses the grease of the high-pressure stage side bearing 15B from turning into oil mist, thereby achieving improved durability and a longer lifespan of the high-pressure stage side bearing 15B.

[0055] (Compressed air supply hole on the low pressure stage side) As shown in FIG. 2 or 5, the low-pressure stage bearing housing 16A includes a compressed air supply hole 91 for supplying compressed air to a gap 38 (in the illustrated example, a gap between the outer circumferential surface 34 of the low-pressure stage sleeve 18A and the inner surface 36 of the low-pressure stage bearing housing 16A) between the rotor 11 including the rotating shaft 3 and the low-pressure stage bearing housing 16A. The compressed air supply hole 91 is formed as a through hole that penetrates the high-pressure stage bearing housing 16B along the radial direction from the outer surface 170 to the inner surface 36 of the low-pressure stage bearing housing 16A. An inlet 91a of the compressed air supply hole 91 is formed on the outer surface 170 of the low-pressure stage bearing housing 16A, and an outlet 91b of the compressed air supply hole 91 is formed on the inner surface 36 of the low-pressure stage bearing housing 16A. The outlet 91b of the compressed air supply hole 91 is located between the low-pressure stage impeller 4 and the low-pressure stage bearing 15A in the axial direction.

[0056] The above-mentioned electric centrifugal compressor 1 includes a compressed air introduction line 29 configured to introduce compressed air from a pressure source (for example, the compressed air supply line 21 or the surge tank 27) to the inlet 91a of the compressed air supply hole 91. The compressed air introduction line 29 shares some of the equipment (pipes and valves) with the above-mentioned compressed air introduction line 26. That is, the compressed air introduction line 29 includes a third pipe 291, one side of which is connected to a branching portion 264 located between the connection portion of the first pipe 261 with the second pipe 262 and the inlet 91a, and the other side of which is connected to the inlet 91a, and a pressure reducing throttle valve 292 provided on the third pipe 291. Note that in some other embodiments, the compressed air introduction line 29 does not need to share equipment with the compressed air introduction line 26.

[0057] 5, a space 33 is formed between a back surface 30 of the low-pressure stage impeller 4 and a low-pressure stage side surface 32 of the low-pressure stage bearing housing 16A facing the back surface 30. In addition, a gap 38 formed between an outer peripheral surface 34 of the low-pressure stage sleeve 18A and an inner surface 36 of the low-pressure stage bearing housing 16A communicates with the space 33.

[0058] In the illustrated embodiment, as shown in FIG. 5, an annular groove 203 into which a seal member (e.g., an annular seal ring) 202 fits, and an annular groove 205 into which a seal member (e.g., an annular seal ring) 204 fits are formed on the outer peripheral surface 34 of the low-pressure stage sleeve 18A.

[0059] The annular groove 203 is located between the low-pressure stage impeller 4 and the outlet 91b of the compressed air supply hole 91 in the axial direction X. The seal member 202 is provided so as to seal the gap 38 at a position between the low-pressure stage impeller 4 and the outlet 91b of the compressed air supply hole 91 in the axial direction X.

[0060] The annular groove 205 is located between the outlet 91b of the compressed air supply hole 91 and the low-pressure stage side bearing 15A in the axial direction. Therefore, the outlet 91b of the compressed air supply hole 91 is located between the annular groove 203 and the annular groove 205 in the axial direction X. The seal member 204 is provided so as to seal the gap 38 at a position between the outlet 91b of the compressed air supply hole 91 and the low-pressure stage side bearing 15A in the axial direction.

[0061] The outer surfaces of the seal members 202 and 204 are in contact with the outer circumferential surface 34 of the low-pressure stage sleeve 18A, and divide the gap 38 into a plurality of parts.

[0062] When the low-pressure stage impeller 4 rotates, the temperature and pressure of the gas present in the space 33 increases. If the gas present in the space 33 passes through the gap 38 and flows into the low-pressure stage side bearing 15A, the grease in the low-pressure stage side bearing 15A may turn into oil mist, causing deterioration of the low-pressure stage side bearing 15A.

[0063] In this regard, according to the above configuration, the low-pressure stage side bearing housing 16A includes a compressed air supply hole 91 for supplying compressed gas from outside the low-pressure stage side bearing housing 16A to a gap 38 between the rotating body 11 including the rotating shaft 3 and the low-pressure stage side bearing housing 16A, and an outlet 91b of the compressed air supply hole 91 is formed on the inner surface 36 of the low-pressure stage side bearing housing 16A and is located between the low-pressure stage impeller 4 and the low-pressure stage side bearing 15A in the axial direction X.

[0064] As a result, compressed gas is supplied to the gap 38 from the compressed air supply hole 91, thereby suppressing leakage flow from the space 33 adjacent to the back surface 30 of the low-pressure stage impeller 4 to the low-pressure stage side bearing 15A. This suppresses the grease in the low-pressure stage side bearing 15A from turning into oil mist due to the leakage flow, and makes it possible to realize improved durability and a longer lifespan of the low-pressure stage side bearing 15A.

[0065] In addition, by supplying compressed air from the compressed air inlet line 29 to the inlet 91a of the compressed air supply hole 91 so that the pressure in the space 206 between the sealing member 202 and the sealing member 204 within the gap 38 becomes greater than the pressure in the space 33 adjacent to the back surface 30 of the low-pressure stage impeller 4, leakage flow from the space 33 adjacent to the back surface 30 of the low-pressure stage impeller 4 to the low-pressure stage side bearing 15A can be effectively suppressed.

[0066] Furthermore, compressed air is supplied from the compressed air introduction line 29 to the inlet 91a of the compressed air supply hole 91 so that the pressure in the space 206 between the seal member 202 and the seal member 204 in the gap 38 becomes greater than the pressure in the space 208 (the space between the seal member 204 and the low-pressure stage bearing 15A) in the gap 38 that accommodates the low-pressure stage bearing 15A, thereby preventing the grease sealed in the low-pressure stage bearing 15A from leaking through the gap 38 or the space 33 into the flow path in the low-pressure stage housing 6. This prevents the grease from being mixed into the compressed gas compressed by the electric centrifugal compressor 1, so that the electric centrifugal compressor 1 can supply clean compressed gas to a fuel cell or the like.

[0067] (Purge hole on the low pressure stage) As shown in Fig. 2 and Fig. 5, the low-pressure stage bearing housing 16A includes a purge hole 93 for discharging the compressed air supplied from the compressed air supply hole 91 to the gap 38 from the gap 38 to the outside of the low-pressure stage bearing housing 16A. The purge hole 93 is formed as a through hole that penetrates the low-pressure stage bearing housing 16A in the radial direction from the outer surface 170 to the inner surface 36 of the low-pressure stage bearing housing 16A. An inlet 93a of the purge hole 93 is formed on the inner surface 36 of the low-pressure stage bearing housing 16A and is located between the low-pressure stage impeller 4 and the low-pressure stage bearing 15A in the axial direction X (between the seal member 204 and the low-pressure stage bearing 15A in the axial direction X in the illustrated example). An outlet 93b of the purge hole 93 is formed on the outer surface 170 of the low-pressure stage bearing housing 16A.

[0068] According to the above configuration, the compressed air supplied to the gap 38 is discharged to the outside of the low-pressure stage side bearing housing 16A through the purge hole 93, so that it is possible to prevent the compressed air supplied to the gap 38 from entering the inside of the low-pressure stage side bearing 15A. This makes it possible to prevent the grease of the low-pressure stage side bearing 15A from turning into oil mist, thereby improving the durability and extending the lifespan of the low-pressure stage side bearing 15A.

[0069] 5, the low-pressure stage bearing 15A includes an inner ring 212, an outer ring 213, a plurality of balls 214 as a plurality of rolling elements held between the inner ring 212 and the outer ring 213, and a pair of annular seal plates 215 positioned on both sides of the balls 214 in the axial direction X and held by the outer ring 213. Here, an annular gap formed between the annular seal plate 215 on the high-pressure stage impeller 5 side of the pair of annular seal plates 215 and the inner ring 212 is defined as a seal plate gap 216, and a cross-sectional area perpendicular to the axial direction X in the seal plate gap 216 is defined as S3. The purge hole 93 may have a passage cross-sectional area S4 larger than the cross-sectional area S3 from the inlet 93a to the outlet 93b. The passage cross-sectional area of ​​purge hole 93 means a cross-sectional area perpendicular to the flow direction of compressed air in purge hole 93 (a cross-sectional area perpendicular to the extending direction of purge hole 93).

[0070] In this way, by having the purge hole 93 have a passage cross-sectional area larger than the cross-sectional area of ​​the seal plate gap 216, it is possible to promote the flow of the compressed air supplied to the gap 38 into the purge hole 93 and suppress the intrusion of the compressed air from the gap 38 into the inside of the low-pressure stage side bearing 15A. This makes it possible to suppress the grease of the low-pressure stage side bearing 15A from turning into oil mist, and to realize improved durability and a longer lifespan of the low-pressure stage side bearing 15A.

[0071] (Lip seal) 6 is an enlarged view of the vicinity of the high-pressure stage sleeve 18B of the electric centrifugal compressor 1 according to one embodiment, and shows a schematic cross section along the rotation axis CA of the electric centrifugal compressor 1. In the configurations shown below, reference numerals common to the configurations described above indicate the same configurations as those described above unless otherwise specified, and description thereof will be omitted.

[0072] In the configuration shown in Figure 3 etc., three seal members 86-88 are provided on the outer peripheral surface 181 of the high pressure stage side sleeve 18B, but in some embodiments, for example as shown in Figure 6, only two seal members 86, 87 may be provided on the outer peripheral surface 181 of the high pressure stage side sleeve 18B.

[0073] The annular groove 182 is located between the high pressure stage impeller 5 and the outlet 90b of the compressed air supply hole 90 in the axial direction X. The seal member 86 is provided so as to seal the gap 25 at a position between the high pressure stage impeller 5 and the outlet 90b of the compressed air supply hole 90 in the axial direction X.

[0074] The annular groove 183 is located between the outlet 90b of the compressed air supply hole 90 and the high-pressure stage side bearing 15B in the axial direction. Therefore, the outlet 90b of the compressed air supply hole 90 is located between the annular groove 182 and the annular groove 183 in the axial direction X. The seal member 87 is provided so as to seal the gap 25 at a position between the outlet 90b of the compressed air supply hole 90 and the high-pressure stage side bearing 15B in the axial direction.

[0075] The outer surfaces of the seal members 86 and 87 are in contact with the outer circumferential surface 181 of the high pressure stage sleeve 18B, and divide the gap 25 into a plurality of parts.

[0076] 6, the electric centrifugal compressor 1 further includes a lip seal 100 provided to seal a gap 25 (in the illustrated example, a gap between an outer peripheral surface 181 of the high-pressure stage sleeve 18B and an inner surface 165 of the high-pressure stage bearing housing 16B) between the rotor 11 including the rotating shaft 3 and the high-pressure stage bearing housing 16B at a position between the seal member 87 and the high-pressure stage bearing 15B in the axial direction X. A base end 100a of the lip seal 100 is fixed to the inner surface 165 of the high-pressure stage bearing housing 16B, and a tip end 100b of the lip seal 100 is configured to be able to abut against the outer peripheral surface 181 of the rotor 11.

[0077] In the example shown in Fig. 6, the inner surface 165 of the high-pressure stage bearing housing 16B includes a first inner surface 165a where the outlet 90b of the compressed air supply hole 90 is formed, and a second inner surface 165c connected to the first inner surface 165a via a stepped surface 165b. The second inner surface 165c is configured to have a larger diameter than the first inner surface 165a and a smaller diameter than the bearing support surface. The lip seal 100 includes a base end portion 100a fixed to the second inner surface 165c, a first connecting portion 100c extending radially inward from the end portion of the base end portion 100a on the high-pressure stage impeller 5 side in the axial direction X along the stepped surface 165b, a second connecting portion 100d connecting the inner peripheral end of the first connecting portion 100c to the tip portion 100b, and the tip portion 100b. The second connection portion 100d extends in an oblique direction intersecting with both the axial direction X and the radial direction Y so as to move radially inward from the inner peripheral end of the first connection portion 100c and toward the high-pressure stage side bearing 15B in the axial direction. The tip portion 100b of the lip seal 100 is formed thicker than each of the base end portion 100a, the first connection portion 100c, and the second connection portion 100d.

[0078] 6, the outer circumferential surface 181 of the high pressure stage sleeve 18B includes a large diameter portion 181a and a small diameter portion 181b having a smaller diameter than the large diameter portion 181a. The large diameter portion 181a is located between the small diameter portion 181b and the high pressure stage impeller 5, and is adjacent to both the small diameter portion 181b and the high pressure stage impeller 5. The annular grooves 182, 183 are formed in the large diameter portion 181a, and the tip portion 100b of the lip seal 100 is configured to be able to abut against the small diameter portion 181b.

[0079] According to the configuration shown in Fig. 6, when the rotating shaft 3 is stopped or when the rotation speed of the rotating shaft 3 is equal to or lower than a reference value, the pressure of the compressed air supplied from the compressed air supply hole 90 to the gap 25 does not separate the tip portion 100b of the lip seal 100 from the outer circumferential surface 181 of the high pressure stage sleeve 18B. For this reason, as shown in Fig. 6, the compressed air supplied to the gap 25 flows into the space 24 between the back surface 57 of the high pressure stage impeller 5 and the high pressure stage side surface 167, and hardly any of the compressed air flows toward the high pressure stage bearing 15B.

[0080] In contrast, when the rotation speed of the rotating shaft 3 exceeds a reference value, the pressure of the compressed air supplied from the compressed air supply hole 90 to the gap 25 causes the tip 100b of the lip seal 100 to separate from the outer circumferential surface 181 of the high-pressure stage sleeve 18B. For this reason, as shown in Fig. 7, the compressed air supplied to the gap 25 flows into the space 24 between the back surface 57 of the high-pressure stage impeller 5 and the high-pressure stage side surface 167, and also flows toward the high-pressure stage bearing 15B, and is discharged from the purge hole 92.

[0081] 6 and 7, when the rotation of the rotating shaft 3 stops, it is possible to prevent the grease in the high-pressure stage bearing 15B from leaking into the flow path in the high-pressure stage housing 5 through the gap 25 and the space 24. This makes it possible to prevent the grease from being mixed into the compressed gas compressed by the electric centrifugal compressor 1, so that the electric centrifugal compressor 1 can supply clean compressed gas to a fuel cell or the like.

[0082] In addition, when the rotation speed of the rotating shaft 3 exceeds a reference value, the tip 100b of the lip seal 100 moves away from the outer peripheral surface 181 of the high pressure stage sleeve 18B, thereby effectively suppressing an increase in the load on the electric motor 10 caused by contact between the tip 100b of the lip seal 100 and the outer peripheral surface 181 of the high pressure stage sleeve 18B when the rotation speed of the rotating shaft 3 is high.

[0083] 8, the electric centrifugal compressor 1 includes a magnetic body 219 (e.g., iron or the like) fixed to the tip portion 100b of the lip seal 100, an electromagnet 220 for separating the tip portion 100b of the lip seal 100 from the outer circumferential surface 181 of the rotor 11, a power supply unit 222 configured to apply a current to the electromagnet 220, a rotation speed sensor 224 for measuring the rotation speed of the rotating shaft 3, and a power supply control unit 226 for controlling the power supply unit 222. In the illustrated example, the magnetic body 219 is fixed to a surface of the tip portion 100b of the lip seal 100 opposite to the high-pressure stage sleeve 18B.

[0084] The power supply control unit 226 may be configured from an electric circuit or may be configured from a computer. When the power supply control unit 226 is configured from a computer, it includes a storage device such as a RAM (Random Access Memory) or a ROM (Read Only Memory) and a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), and the processor executes a program stored in the storage device to realize its functions.

[0085] The power supply control unit 226 is configured to apply a current to the electromagnet 220 based on the rotation speed of the rotating shaft 3 measured by the rotation speed sensor 224. For example, the power supply control unit 226 may be configured to apply a current to the electromagnet 220 to separate the tip portion 100b of the lip seal 100 from the outer circumferential surface 181 of the rotor 11 when the rotation speed of the rotating shaft 3 measured by the rotation speed sensor 224 exceeds a reference value.

[0086] 8, when the rotation speed of the rotating shaft 3 measured by the rotation speed sensor 224 is equal to or lower than a reference value, the power supply control unit 226 does not energize the electromagnet 220, so that the tip portion 100b of the lip seal 100 does not separate from the outer circumferential surface 181 of the high pressure stage sleeve 18B by only the pressure of the compressed air supplied from the compressed air supply hole 90 to the gap 25. For this reason, as shown in FIG. 8, the compressed air supplied to the gap 25 flows into the space 24 between the back surface 57 of the high pressure stage impeller 5 and the high pressure stage side surface 167, and hardly flows toward the high pressure stage side bearing 15B.

[0087] On the other hand, when the rotation speed of the rotating shaft 3 measured by the rotation speed sensor 224 exceeds a reference value, the power supply control unit 226 controls the power supply unit 222 to pass current through the electromagnet 220, thereby attracting the magnetic body 219 and the tip portion 100b to which the magnetic body 219 is fixed to the electromagnet 220, and moving the tip portion 100b away from the outer peripheral surface 181 of the high-pressure stage sleeve 18B.

[0088] Therefore, as shown in Figure 9, the compressed air supplied to the gap 25 flows into the space 24 between the back surface 57 of the high-pressure stage impeller 5 and the high-pressure stage side surface 167, and also flows toward the high-pressure stage side bearing 15B, and is discharged through the purge hole 92.

[0089] 8 and 9, when the rotation speed of the rotating shaft 3 is equal to or lower than a reference value, it is possible to prevent the grease in the low-pressure stage bearing 15A from leaking into the flow path in the low-pressure stage housing 6 through the gap 25 or the space 24. This makes it possible to prevent the grease from being mixed into the compressed gas compressed by the electric centrifugal compressor 1, so that the electric centrifugal compressor 1 can supply clean compressed gas to a fuel cell or the like.

[0090] In addition, when the rotation speed of the rotating shaft 3 exceeds a reference value, the tip 100b of the lip seal 100 moves away from the outer peripheral surface 181 of the high pressure stage sleeve 18B more reliably than the configurations shown in Figures 6 and 7, so that an increase in the load on the electric motor 10 caused by contact between the tip 100b of the lip seal 100 and the outer peripheral surface 181 of the high pressure stage sleeve 18B when the rotation speed of the rotating shaft 3 is high can be effectively suppressed.

[0091] (Negative pressure pump) 10, the electric centrifugal compressor 1 may further include a negative pressure pump 230 for sucking air from each of the purge hole 92 and the purge hole 93. The electric centrifugal compressor 1 shown in FIG. 10 further includes a purge line 232 connecting the outlet 92b of the purge hole 92 and the negative pressure pump 230, and a purge line 234 connecting the outlet 93b of the purge hole 93 and the negative pressure pump 230.

[0092] 10 further includes a pump control unit 236 that controls the negative pressure pump 230, and the pump control unit 236 is configured to operate the negative pressure pump 230 when the electric motor 10 is stopped to suck air from each of the purge holes 92 and 93. The pump control unit 236 may be configured from an electric circuit or may be configured from a computer. When the pump control unit 236 is configured from a computer, it includes a storage device such as a RAM (Random Access Memory) or a ROM, and a processor such as a CPU or a GPU, and the processor executes a program stored in the storage device to realize its functions.

[0093] According to the configuration shown in Figure 10, when the electric motor 10 is stopped, the negative pressure pump 230 is operated to evacuate the internal air of the high-pressure stage bearing housing 16B through the purge hole 92, thereby preventing the grease sealed in the high-pressure stage bearing 15B from leaking into the flow path in the high-pressure stage housing 7 through the gap 25 or space 24.

[0094] In addition, by operating the negative pressure pump 230 to evacuate the internal air of the low-pressure stage bearing housing 16A through the purge hole 93 when the electric motor 10 is stopped, it is possible to prevent the grease sealed in the low-pressure stage bearing 15A from leaking into the flow path inside the low-pressure stage housing 6 through the gap 38 or space 33.

[0095] Therefore, even without providing a lip seal 100 as shown in Figures 6 to 10, it is possible to effectively prevent grease from being mixed into the compressed gas compressed by the electric centrifugal compressor 1, and clean compressed gas can be supplied to fuel cells, etc.

[0096] The present disclosure is not limited to the above-described embodiments, and includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0097] For example, in the above-described embodiment, a multi-stage electric centrifugal compressor is exemplified, but in other embodiments, a single-stage electric centrifugal compressor may be used.

[0098] 6 to 9, the electric centrifugal compressor 1 includes a lip seal 100 provided between the seal member 87 and the high-pressure stage bearing 15B in the axial direction X to seal the gap 25 between the rotor 11 including the rotating shaft 3 and the high-pressure stage bearing housing 16B. In other embodiments, the electric centrifugal compressor 1 may include a lip seal provided between the seal member 204 and the low-pressure stage bearing 15A in the axial direction X to seal the gap 38 between the rotor 11 including the rotating shaft 3 and the low-pressure stage bearing housing 16A in the configuration shown in FIG. 5, for example.

[0099] This makes it possible to prevent grease in the low-pressure stage bearing 15A from leaking into the flow path in the low-pressure stage housing 6 through the gap 38 and the space 33 when the rotation of the rotating shaft 3 stops. This makes it possible to prevent grease from being mixed into the compressed gas compressed by the electric centrifugal compressor 1, so that the electric centrifugal compressor 1 can supply clean compressed gas to a fuel cell or the like.

[0100] The contents described in the above-mentioned embodiments can be understood, for example, as follows.

[0101] (1) An electric centrifugal compressor according to the present disclosure (for example, the electric centrifugal compressor 1 described above) has the following features: an electric motor (such as the electric motor 10 described above) including a rotating shaft (such as the rotating shaft 3 described above); A first impeller (for example, the above-mentioned low pressure stage impeller 4 or high pressure stage impeller 5) provided on one end side of the rotating shaft; A first bearing (for example, the above-mentioned low pressure stage side bearing 15A or the above-mentioned high pressure stage side bearing 15B) that rotatably supports the rotating shaft at a position between the first impeller and the electric motor and contains a lubricant (for example, the above-mentioned grease); A first bearing housing (for example, the above-mentioned low pressure stage side bearing housing 16A or the high pressure stage side bearing housing 16B) that accommodates the first bearing; Equipped with the first bearing housing includes a compressed gas supply hole (e.g., the above-mentioned compressed air supply hole 90 or compressed air supply hole 91) for supplying compressed gas from outside the first bearing housing to a gap (e.g., the above-mentioned gap 25 or gap 38) between the first bearing housing and a rotating body including the rotating shaft (e.g., the above-mentioned rotating body 11), An outlet of the compressed gas supply hole (for example, the above-mentioned outlet 90b or outlet 91b) is provided on the inner surface of the first bearing housing and is located between the first impeller and the first bearing in the axial direction of the rotating shaft.

[0102] According to the electric centrifugal compressor described in (1) above, compressed gas is supplied from the compressed gas supply hole of the first bearing housing to the gap between the rotor and the first bearing housing, so that leakage flow from the space adjacent to the back surface of the first impeller to the first bearing can be suppressed. This makes it possible to suppress deterioration of the lubricant in the first bearing caused by the leakage flow, thereby improving the durability and extending the life of the first bearing.

[0103] In addition, the lubricant of the first bearing can be prevented from leaking into the flow passage on the mainstream side that flows through the first impeller through the gap between the rotor and the first bearing housing or through the space adjacent to the back surface of the first impeller. This prevents the lubricant from being mixed into the compressed gas compressed by the electric centrifugal compressor, allowing the electric centrifugal compressor to discharge clean compressed gas. In addition, since the lubricant can be prevented from being mixed into the compressed gas generated even when a first bearing containing lubricant is used, the structure of the parts around the first bearing can be simplified compared to the case where an air bearing is used to generate clean compressed gas, and the electric centrifugal compressor can be made smaller and lighter.

[0104] (2) In some embodiments, in the electric centrifugal compressor according to (1) above, a first seal member (e.g., the above-mentioned seal member 86 or seal member 202) provided to seal the gap at a position between the first impeller and the outlet of the compressed gas supply hole in the axial direction; a second seal member (e.g., the above-mentioned seal member 87, seal member 88, or seal member 204) provided to seal the gap at a position between the outlet of the compressed gas supply hole and the first bearing in the axial direction; It further comprises:

[0105] According to the electric centrifugal compressor described in (2) above, by providing an outlet for the compressed gas supply hole in the space between the first seal member and the second seal member in the gap between the rotor and the first bearing housing, leakage flow from the space adjacent to the back surface of the first impeller to the first bearing can be effectively suppressed, and leakage of lubricant for the first bearing through the gap between the rotor and the first bearing housing or the space adjacent to the back surface of the first impeller to the mainstream flow side flowing through the first impeller can be effectively suppressed.

[0106] (3) In some embodiments, in the electric centrifugal compressor according to (2) above, The rotor further includes a third seal member (eg, the above-mentioned seal member 88) provided to seal the gap at a position between the second seal member (eg, the above-mentioned seal member 87) and the first bearing in the axial direction.

[0107] According to the electric centrifugal compressor described above in (3), it is possible to effectively prevent the lubricant of the first bearing from leaking into the mainstream flowing through the first impeller through the gap between the rotor and the first bearing housing or through the space adjacent to the back surface of the first impeller.

[0108] (4) In some embodiments, in the electric centrifugal compressor according to (2) or (3), The gap further includes a compressed gas inlet line (e.g., the above-mentioned compressed air inlet line 26 or compressed air inlet line 29) configured to introduce the compressed gas into the inlet of the compressed gas supply hole (e.g., the above-mentioned inlet 90a or 91a) so that the pressure in the space between the first sealing member and the second sealing member in the gap is greater than the pressure in the space adjacent to the back surface of the first impeller (e.g., the above-mentioned space 24 or space 33).

[0109] According to the electric centrifugal compressor described above in (4), by making the pressure in the space between the first seal member and the second seal member in the gap greater than the pressure in the space adjacent to the back surface of the first impeller, leakage flow from the space adjacent to the back surface of the first impeller to the first bearing can be effectively suppressed.

[0110] (5) In some embodiments, in the electric centrifugal compressor according to any one of (2) to (4), The bearing further includes a lip seal (for example, the above-mentioned lip seal 100) provided to seal the gap at a position between the second seal member and the first bearing in the axial direction.

[0111] According to the electric centrifugal compressor described in (5) above, when the rotation of the rotating shaft stops, it is possible to effectively prevent the lubricant in the first bearing from leaking through the gap or the space adjacent to the back surface of the impeller into the mainstream flowing through the first impeller.

[0112] (6) In some embodiments, in the electric centrifugal compressor according to (5) above, A base end portion of the lip seal (for example, the above-mentioned base end portion 100a) is fixed to the first bearing housing, and a tip end portion of the lip seal (for example, the above-mentioned tip end portion 100b) is configured to be able to abut against the outer circumferential surface of the rotating body.

[0113] According to the electric centrifugal compressor described in (6) above, when the rotation of the rotating shaft stops, it is possible to effectively prevent the lubricant in the first bearing from leaking through the gap or the space adjacent to the back surface of the impeller into the mainstream flowing through the first impeller.

[0114] (7) In some embodiments, in the electric centrifugal compressor according to (6) above, The rotor further includes an electromagnet (for example, the electromagnet 220 described above) for separating the tip of the lip seal from the outer circumferential surface of the rotor.

[0115] According to the electric centrifugal compressor of the above (7), by passing a current through the electromagnet to separate the tip of the lip seal from the outer circumferential surface of the rotor, it is possible to suppress an increase in the load on the electric motor caused by the lip seal rubbing against the outer circumferential surface of the rotor.

[0116] (8) In some embodiments, in the electric centrifugal compressor according to (7) above, a power supply unit (e.g., power supply unit 222 described above) configured to apply a current to the electromagnet; A rotation speed sensor (e.g., the above-mentioned rotation speed sensor 224) for measuring the rotation speed of the rotating shaft; a power supply control unit (such as the above-mentioned power supply control unit 226) for controlling the power supply unit; Equipped with The power supply control unit is configured to apply a current to the electromagnet based on the rotation speed of the rotating shaft measured by the rotation speed sensor.

[0117] According to the electric centrifugal compressor described above in (8), by passing a current through the electromagnet based on the rotation speed of the rotating shaft, it is possible to suppress an increase in the load of the electric motor that corresponds to the rotation speed of the rotating shaft.

[0118] (9) In some embodiments, in the electric centrifugal compressor according to (8) above, The power supply control unit is configured to pass a current through the electromagnet to separate the tip of the lip seal from the outer peripheral surface of the rotating body when the rotation speed of the rotating shaft measured by the rotation speed sensor exceeds a reference value.

[0119] According to the electric centrifugal compressor described above in (9), it is possible to effectively suppress an increase in the load on the electric motor caused by contact between the tip end of the lip seal and the outer peripheral surface of the rotor when the rotation speed of the rotating shaft is higher than a reference value.

[0120] (10) In some embodiments, in the electric centrifugal compressor according to any one of (2) to (9), The first bearing housing includes a purge hole (e.g., the above-mentioned purge hole 92 or purge hole 93) for discharging the compressed gas supplied from the compressed gas supply hole to the gap from the gap to the outside of the first bearing housing, The inlet of the purge hole (for example, the above-mentioned inlet 92a or inlet 93a) is provided on the inner surface of the first bearing housing, and is located between the first impeller and the first bearing in the axial direction.

[0121] According to the electric centrifugal compressor described in (10) above, the compressed gas supplied to the gap between the rotor and the first bearing housing is discharged to the outside of the first bearing housing through the purge hole, so that the compressed gas supplied to the gap can be prevented from entering the inside of the first bearing. This makes it possible to prevent deterioration of the lubricant in the first bearing and to realize improved durability and a longer lifespan of the first bearing.

[0122] (11) In some embodiments, in the electric centrifugal compressor according to (10), The first bearing includes an inner ring (e.g., the above-mentioned inner ring 94 or inner ring 212), an outer ring (e.g., the above-mentioned outer ring 95 or outer ring 213), a plurality of rolling elements (e.g., the above-mentioned plurality of balls 96 or the above-mentioned plurality of balls 214) held between the inner ring and the outer ring, and a pair of annular seal plates (e.g., the above-mentioned pair of annular seal plates 97 or the above-mentioned pair of annular seal plates 215) positioned on both sides of the rolling elements in the axial direction and held by the outer ring, If an annular gap formed between the annular seal plate on the first impeller side of the pair of annular seal plates and the inner ring is defined as a seal plate gap (for example, the above-mentioned seal plate gap 98 or seal plate gap 216), A passage cross-sectional area of ​​the purge hole is larger than a cross-sectional area of ​​the seal plate gap perpendicular to the axial direction.

[0123] According to the electric centrifugal compressor described in (11) above, the purge hole has a passage cross-sectional area larger than the cross-sectional area of ​​the seal plate gap, which promotes the flow of compressed gas supplied to the gap between the rotor and the first bearing housing to the purge hole, thereby making it possible to suppress the intrusion of compressed gas into the first bearing through the gap between the rotor and the first bearing housing. This makes it possible to suppress deterioration of the lubricant in the first bearing and to realize improved durability and a longer lifespan of the first bearing.

[0124] (12) In some embodiments, in the electric centrifugal compressor according to (10) or (11), It further includes a negative pressure pump (such as the above-mentioned negative pressure pump 230) for sucking gas out of the purge hole.

[0125] According to the electric centrifugal compressor described in (12) above, by operating the negative pressure pump when the electric motor is stopped to suck out the internal air of the first bearing housing through the purge hole, it is possible to prevent the lubricant of the first bearing from leaking into the main flow path flowing through the first impeller through the gap between the rotor and the first bearing housing or through the space adjacent to the back surface of the first impeller.

[0126] (13) In some embodiments, in the electric centrifugal compressor according to (12), Further comprising a pump control unit (e.g., the above-mentioned pump control unit 236) for controlling the negative pressure pump; The pump control unit is configured to operate the negative pressure pump when the electric motor is stopped.

[0127] According to the electric centrifugal compressor described in (13) above, by automatically operating the negative pressure pump when the electric motor is stopped to suck out the internal air of the first bearing housing through the purge hole, it is possible to prevent the lubricant of the first bearing from leaking into the main flow path flowing through the first impeller through the gap between the rotor and the first shaft housing or through the space adjacent to the back surface of the first impeller.

[0128] (14) In some embodiments, in the electric centrifugal compressor according to any one of (1) to (13), The electric centrifugal compressor is a multi-stage electric centrifugal compressor, A second impeller (for example, the above-mentioned low pressure stage impeller 4 or high pressure stage impeller 5) provided on the other end side of the rotating shaft; A second bearing (for example, the above-mentioned low pressure stage side bearing 15A or the above-mentioned high pressure stage side bearing 15B) that rotatably supports the rotating shaft at a position between the second impeller and the electric motor and contains a lubricant (for example, the above-mentioned grease); A second bearing housing (for example, the above-mentioned low pressure stage side bearing housing 16A or the high pressure stage side bearing housing 16B) that accommodates the second bearing; Equipped with The second bearing housing includes a compressed gas supply hole (e.g., the above-mentioned compressed air supply hole 90 or compressed air supply hole 91) for supplying compressed gas to a gap (e.g., the above-mentioned gap 25 or gap 38) between a rotating body including the rotating shaft and the second bearing housing, An outlet of the compressed gas supply hole of the second bearing housing (for example, the above-mentioned outlet 90b or outlet 91b) is located between the second impeller and the second bearing in the axial direction.

[0129] According to the electric centrifugal compressor described in (14) above, compressed gas is supplied from the compressed gas supply hole of the second bearing housing to the gap between the rotor and the second bearing housing, so that leakage flow from the space adjacent to the back surface of the second impeller to the second bearing can be suppressed. This makes it possible to suppress deterioration of the lubricant in the second bearing caused by the leakage flow, and to realize improved durability and a longer lifespan of the second bearing.

[0130] In addition, it is possible to prevent the lubricant for the second bearing from leaking into the flow passage on the mainstream side that flows through the second impeller through the gap between the rotor and the second bearing housing or through the space adjacent to the back surface of the second impeller. This makes it possible to prevent the lubricant from being mixed into the compressed gas compressed by the electric centrifugal compressor, enabling the electric centrifugal compressor to discharge clean compressed gas.

[0131] (15) In some embodiments, in the electric centrifugal compressor according to (14), A low-pressure stage housing (for example, the above-mentioned low-pressure stage housing 6) that accommodates the first impeller; A high-pressure stage housing (for example, the above-mentioned high-pressure stage housing 7) that accommodates the second impeller; a connecting pipe (for example, the above-mentioned connecting pipe 8) for supplying the compressed gas compressed by the first impeller to the high-pressure stage housing, The high-pressure stage housing has a high-pressure stage inlet opening (for example, the above-mentioned high-pressure stage inlet opening 71) that opens in a direction intersecting with the axis of the rotating shaft, The tie-up line is connected to the high pressure stage inlet opening.

[0132] According to the electric centrifugal compressor described in (15) above, the high-pressure stage housing has a high-pressure stage inlet opening that opens in a direction intersecting the axis of the rotating shaft, and a connecting pipe is connected to the high-pressure stage inlet opening. Therefore, the compressed gas compressed by the first impeller is supplied to the inside of the high-pressure stage housing from the outer periphery side of the high-pressure stage housing through the connecting pipe. In this case, the length of the connecting pipe and the high-pressure stage housing in the axial direction can be made shorter than when the compressed gas is introduced into the high-pressure stage housing along the axial direction of the rotating shaft. This allows the length of the multi-stage electric centrifugal compressor in the axial direction to be shortened, thereby making it possible to reduce the size and weight of the multi-stage electric centrifugal compressor. In addition, a high pressure ratio can be achieved at a low flow rate, and a multi-stage electric centrifugal compressor with excellent thrust load balance can be realized. [Explanation of symbols]

[0133] 1 Electric centrifugal compressor 3 Rotating shaft 4. Low pressure stage impeller 5. High pressure stage impeller 6 Low pressure stage housing 7 High pressure stage housing 8 Connecting piping 10 Electric motor 11 Rotating Body 12 Motor stator 13 Rotor Assembly 14 Permanent magnets 15A Low pressure stage bearing 15B High pressure stage bearing 16A Low pressure stage bearing housing 16B High pressure stage bearing housing 17 Stator housing 18A Low pressure stage sleeve 18B High pressure stage sleeve 19 Pressure spring 21 Compressed air supply line 24,33,79,89,206,208 space 25,38 Gap 26,29 Compressed air introduction line 27 Surge Tank 28 Compressor 30,57 Back 32 Low pressure stage side 34,181 Outer surface 36,165 Inside 41,51 Hub 43,53 Impeller blade 61 Low pressure stage inlet opening 62 Low pressure stage outlet opening 63,73 Supply channel 64,74 Scroll flow passage 66 Low pressure stage impeller chamber 71 High pressure stage inlet opening 72 High pressure stage outlet opening 76 High pressure stage impeller chamber 81 High pressure stage side connection 82 Low-voltage stage side connection 83 Middle Section 84 Low pressure stage side curve 85 High pressure stage side curve 86, 87, 88, 202, 204 Sealing materials 90,91 Compressed air supply hole 90a,91a,92a,93a Entrance 90b,91b,92b,93b Exit 92,93 Purge holes 94,212 Inner circle 95,213 Outer ring 96,214 balls 97,215 Annular seal plate 98,216 Seal plate gap 100 Lip seal 100a Base end 100b Tip 100c First connection part 100d Second connection part 161,162 Bearing support surface 164,166 Locking surface 165a First inner surface 165b Step surface 165c 2nd inner surface 167 High pressure stage side 168,170 Exterior 181a Large diameter section 181b Small diameter section 182,183,184,203,205 Annular groove 211,264 Branch 219 Magnetic material 220 Electromagnet 222 Power supply unit 224 Rotational speed sensor 226 Power supply control section 230 Negative pressure pump 232,234 Purge Line 236 Pump control section 261 First Pipe 262 Second Pipe 263 Switching Device 291 Third Pipe 292 Pressure reducing throttle valve CA (rotating shaft) axis X-axis direction XH (Axial) High Pressure Stage Side XL (Axial) Low pressure stage side Y radial direction

Claims

1. an electric motor including a rotating shaft; A first impeller provided on one end side of the rotating shaft; a first bearing that rotatably supports the rotating shaft at a position between the first impeller and the electric motor and that contains a lubricant; a first bearing housing that accommodates the first bearing; An electric centrifugal compressor comprising: the first bearing housing includes a compressed gas supply hole for supplying compressed gas from an outside of the first bearing housing to a gap between the first bearing housing and a rotating body including the rotating shaft, an outlet of the compressed gas supply hole is provided on an inner surface of the first bearing housing and is located between the first impeller and the first bearing in the axial direction of the rotating shaft; The electric centrifugal compressor comprises: a first seal member provided to seal the gap at a position between the first impeller and the outlet of the compressed gas supply hole in the axial direction; a second seal member provided to seal the gap at a position between the outlet of the compressed gas supply hole and the first bearing in the axial direction; a lip seal provided to seal the gap at a position between the second seal member and the first bearing in the axial direction; Further comprising: a base end of the lip seal is fixed to the first bearing housing, and a tip end of the lip seal is configured to be able to abut against an outer circumferential surface of the rotating body, The electric centrifugal compressor further comprises an electromagnet for separating a tip end of the lip seal from an outer circumferential surface of the rotating body.

2. 2. The electric centrifugal compressor according to claim 1, further comprising a third seal member provided to seal the gap at a position between the second seal member and the first bearing in the axial direction.

3. 3. The electric centrifugal compressor according to claim 1, further comprising a compressed gas introduction line configured to introduce the compressed gas to an inlet of the compressed gas supply hole so that a pressure in a space in the gap between the first seal member and the second seal member is greater than a pressure in a space adjacent to a back surface of the first impeller.

4. a power supply unit configured to apply a current to the electromagnet; a rotation speed sensor for measuring the rotation speed of the rotating shaft; a power supply control unit for controlling the power supply unit; Equipped with The electric centrifugal compressor according to claim 1 , wherein the power supply control unit is configured to apply a current to the electromagnet based on a rotation speed of the rotating shaft measured by the rotation speed sensor.

5. 5. The electric centrifugal compressor according to claim 4, wherein the power supply control unit is configured to, when the rotation speed of the rotating shaft measured by the rotation speed sensor exceeds a reference value, pass a current through the electromagnet to separate the tip portion of the lip seal from the outer circumferential surface of the rotating body.

6. the first bearing housing includes a purge hole for discharging the compressed gas supplied from the compressed gas supply hole to the gap from the gap to an outside of the first bearing housing, 6. The electric centrifugal compressor according to claim 1, wherein an inlet of the purge hole is provided on an inner surface of the first bearing housing and is located between the first impeller and the first bearing in the axial direction.

7. the first bearing includes an inner ring, an outer ring, a plurality of rolling elements held between the inner ring and the outer ring, and a pair of annular seal plates positioned on either side of the rolling elements in the axial direction and held by the outer ring, When an annular gap formed between the annular seal plate on the first impeller side of the pair of annular seal plates and the inner ring is defined as a seal plate gap, The electric centrifugal compressor according to claim 6 , wherein a passage cross-sectional area of ​​the purge hole is larger than a cross-sectional area of ​​the seal plate gap perpendicular to the axial direction.

8. The electric centrifugal compressor according to claim 6 or 7, further comprising a negative pressure pump for sucking gas out from the purge hole.

9. A pump control unit for controlling the negative pressure pump is further provided. The electric centrifugal compressor according to claim 8 , wherein the pump control unit is configured to operate the negative pressure pump when the electric motor is stopped.

10. The electric centrifugal compressor is a multi-stage electric centrifugal compressor, A second impeller provided on the other end side of the rotating shaft; a second bearing that rotatably supports the rotating shaft at a position between the second impeller and the electric motor and that contains a lubricant; a second bearing housing that accommodates the second bearing; Equipped with the second bearing housing includes a compressed gas supply hole for supplying compressed gas to a gap between the rotating body and the second bearing housing, 10. The electric centrifugal compressor according to claim 1, wherein an outlet of the compressed gas supply hole of the second bearing housing is located between the second impeller and the second bearing in the axial direction.

11. an electric motor including a rotating shaft; A first impeller provided on one end side of the rotating shaft; a first bearing that rotatably supports the rotating shaft at a position between the first impeller and the electric motor and that contains a lubricant; a first bearing housing that accommodates the first bearing; An electric centrifugal compressor comprising: the first bearing housing includes a compressed gas supply hole for supplying compressed gas from an outside of the first bearing housing to a gap between the first bearing housing and a rotating body including the rotating shaft, an outlet of the compressed gas supply hole is provided on an inner surface of the first bearing housing and is located between the first impeller and the first bearing in the axial direction of the rotating shaft; The electric centrifugal compressor is a multi-stage electric centrifugal compressor, A second impeller provided on the other end side of the rotating shaft; a second bearing that rotatably supports the rotating shaft at a position between the second impeller and the electric motor and that contains a lubricant; a second bearing housing that accommodates the second bearing; Equipped with the second bearing housing includes a compressed gas supply hole for supplying compressed gas to a gap between the rotating body and the second bearing housing, an outlet of the compressed gas supply hole of the second bearing housing is located between the second impeller and the second bearing in the axial direction, The electric centrifugal compressor comprises: a low pressure stage housing that houses the first impeller; a high pressure stage housing that houses the second impeller; a connecting pipe for supplying the compressed gas compressed by the first impeller to the high-pressure stage housing, the high-pressure stage housing has a high-pressure stage inlet opening that opens in a direction intersecting with an axis of the rotating shaft, The connecting pipe is connected to the high pressure stage inlet opening, a surge tank for storing compressed air compressed by a compressor other than the electric centrifugal compressor; a switching device configured to be able to switch a supply source of the compressed air to each of the inlet of the compressed gas supply hole of the first bearing housing and the inlet of the compressed gas supply hole of the second bearing housing to either a compressed air supply line through which compressed air compressed by the second impeller flows or the surge tank; The electric centrifugal compressor further comprises:

12. The electric centrifugal compressor according to claim 11, wherein the high-pressure stage inlet opening opens in a direction perpendicular to an axis of the rotating shaft.

Images