electric machine

Abstract

The motor includes a shaft (10), a rotor (100), a stator (200), and a frame (300). The shaft is rotatably supported on the frame with axial location sleeve bearings (20, 30B) located at each axial end of the shaft. The axial clearance that limits axial movement of the shaft in one of the two axial location sleeve bearings is larger than the axial clearance in the other of the two axial location sleeve bearings. During normal operating conditions, axial movement of the shaft is limited only by the bearing with the smaller axial clearance, and during abnormal events, axial movement of the shaft is limited by both bearings, with the bearing with the larger axial clearance reducing the axial load of the first bearing.

Description

Technical Field

[0001] This invention relates to electric motors. Background Technology

[0002] An electric motor may consist of a rotor, a stator surrounding the rotor, and a frame surrounding the stator.

[0003] The motor shaft can be rotatably supported on the frame using bearings located at both the drive and non-drive ends of the motor. The bearings can be sleeve bearings, whereby one of the motor's sleeve bearings can be an axially locating sleeve bearing, and the other sleeve bearing can be a conventional sleeve bearing without any axial locating capability. The axially locating sleeve bearing can be located at the drive end of the motor.

[0004] An actual axial bearing is also provided, comprising: a disc attached to the shaft; and a support element acting radially outward on the outer surface of the shaft against the opposite surface of the disc. The support element may be supported in a bearing frame. However, the actual axial bearing is an expensive component and is therefore used only in critical applications.

[0005] Earthquakes cause ground acceleration, which exerts stress on the motor. The biggest problem during an earthquake is keeping the rotor in its position. Summary of the Invention

[0006] The purpose of this invention is to obtain an improved motor.

[0007] The motor according to the invention is defined in claim 1.

[0008] The motor includes:

[0009] axis,

[0010] The rotor, which is supported on the shaft,

[0011] The stator, which surrounds the rotor,

[0012] The frame, which surrounds the stator,

[0013] The bearings at the drive end and the non-drive end of the motor are used to rotatably support the shaft on the frame; both bearings are sleeve bearings.

[0014] The motor is characterized by

[0015] Both bearings are axial locating sleeve bearings. The axial clearance of one of the two axial locating sleeve bearings, which restricts the axial movement of the shaft, is larger than that of the other axial locating sleeve bearing. This means that during normal operation, the axial movement of the shaft is restricted only by the bearing with the smaller axial clearance. However, during abnormal events, such as earthquakes, the axial movement of the shaft is restricted by both bearings. In such abnormal events, the bearing with the larger axial clearance reduces the axial load on the first bearing.

[0016] This invention provides an efficient method for addressing the problem of maintaining a rotor in a predetermined axial position during an earthquake event. Under normal operating conditions, bearings with large axial clearance do not participate in restricting the rotor's axial movement. Only during abnormal seismic events, such as earthquakes, do bearings with large axial clearance restrict the rotor's axial movement. During an earthquake, bearings with large axial clearance may bear 50% of the total axial impact load after the initial threshold force has already been reached.

[0017] This can be achieved by arranging axial locating sleeve bearings at each end of the motor. The axial clearance of one of the axial locating sleeve bearings can be larger than that of the other. The larger axial clearance can be sized so that anticipated thermal expansion does not activate the axial positioning of the bearing with the larger clearance; that is, they are handled by the axial positioning of the bearing with the smaller axial clearance. The impact load during an earthquake can be estimated to be approximately 800 kN. During an earthquake, the axial deformation of the axial locating sleeve bearing with the smaller axial clearance may be several millimeters.

[0018] Axial positioning sleeve bearings are bearings that bear axial loads.

[0019] The motor can be an electric motor or a generator.

[0020] The motor can be a large motor. The shaft height of the motor can range from 1120mm to 2000mm. The motor can be a high-voltage motor. The motor can be a fin-cooled motor. The output power of the motor can range from 1MW to 25MW. The voltage of the motor can be up to 11.5kV. Attached Figure Description

[0021] The invention will now be described in more detail with reference to the accompanying drawings, in which:

[0022] Figure 1A shows the axial cross-section of a motor according to the prior art.

[0023] Figure 1B An axial cross-section of an electric motor according to an embodiment of the present invention is shown.

[0024] Figure 2 An axial positioning sleeve bearing according to an embodiment of the present invention is shown.

[0025] Figure 3A shows a conventional sleeve bearing without axial positioning according to the prior art.

[0026] Figure 3B An axially locating sleeve bearing located on the non-drive side according to an embodiment of the present invention is shown.

[0027] Figure 4 A sleeve bearing mounted on a base for an electric motor according to an embodiment of the present invention is shown.

[0028] Figure 5 A sleeve bearing mounted on a flange is shown for an electric motor according to an embodiment of the present invention. Detailed Implementation

[0029] Figure 1A shows an axial cross-section of a motor according to the prior art.

[0030] The motor may include a shaft 10, a rotor 100, a stator 200, and a frame 300.

[0031] Shaft 10 can be rotatably supported by bearings 20 and 30A located at the driving end D and the non-driving end N of the motor. Bearings 20 and 30A can be positioned within bearing housings 40 and 50A arranged outside the end plates 320 and 330 of frame 300. The first end plate 320 of the two end plates 320 and 330 can be attached to the first axial end of frame 300 at the driving end D of the motor. The second end plate 330 of the two end plates 320 and 330 can be attached to the second axial end of frame 300 at the non-driving end N of the motor. The first axial end of frame 300 is opposite to the second axial end of frame 300. Shaft 10 can rotate about the axis of rotation XX. The driving end D of the motor is located on the left side of the figure, and the non-driving end N of the motor is located on the right side of the figure.

[0032] The rotor 100 can be mounted on a cylindrical intermediate portion 11 supported on the shaft 10, so that the rotor 100 rotates synchronously with the shaft 10. The rotor 100 may include rotor windings 110.

[0033] The stator 200 may surround the rotor 100. The stator 200 may be attached to the frame 300. The frame 300 may surround the stator 200. Both the stator 200 and the frame 300 are fixed.

[0034] The stator 200 may include a stator core 210 and a stator winding 220. The stator winding 220 may be positioned in an axial groove disposed on the inner surface of the stator core 210. The stator winding 220 may also include end portions 220A, 220B extending outward from opposite axial ends of the stator core 210.

[0035] The motor exciter 60 is positioned on the shaft 10 within the motor frame 300.

[0036] There is an air gap G between the inner periphery of the stator core 210 and the outer periphery of the rotor 100.

[0037] The frame 300 may include a cover 310 that covers the motor from the top. In this embodiment, bearings 20 and 30A are mounted on a base. Bearing housings 40 and 50A are supported on support blocks 340 and 350. Support blocks 340 and 350 may be supported on a floor in the field.

[0038] A first axial air passage may be formed between the outer periphery of the rotor 100 and the inner periphery of the stator 200. A second axial air passage may be formed between the outer periphery of the stator core 210 and the frame 300. The stator core 210 and the rotor 100 may have a laminated structure formed from a set of sheets.

[0039] The first bearing 20, located on the drive side of the motor, can be an axially locating sleeve bearing. The second bearing 30A, located on the non-drive side of the motor, can be a conventional sleeve bearing. This is a conventional prior art method for handling axial forces in a motor. Only one of the bearings, typically the drive end bearing 20, is an axially locating sleeve bearing capable of withstanding axial forces to hold the shaft 10 axially in the correct position during normal operating conditions.

[0040] Figure 1B An axial cross-section of an electric motor according to an embodiment of the present invention is shown.

[0041] The motor may include a shaft 10, a rotor 100, a stator 200, and a frame 300.

[0042] Shaft 10 can be rotatably supported by bearings 20 and 30B located at the driving end D and the non-driving end N of the motor. Bearings 20 and 30B can be positioned within bearing housings 40 and 50B arranged outside the end plates 320 and 330 of frame 300. The first end plate 320 of the two end plates 320 and 330 can be attached to the first axial end of frame 300 at the driving end D of the motor. The second end plate 330 of the two end plates 320 and 330 can be attached to the second axial end of frame 300 at the non-driving end N of the motor. The first axial end of frame 300 is opposite to the second axial end of frame 300. Shaft 10 can rotate about the axis of rotation XX. The driving end D of the motor is located on the left side of the figure, and the non-driving end N of the motor is located on the right side of the figure.

[0043] The rotor 100 can be mounted on a cylindrical intermediate portion 11 supported on the shaft 10, so that the rotor 100 rotates synchronously with the shaft 10. The rotor 100 may include rotor windings 110.

[0044] The stator 200 may surround the rotor 100. The stator 200 may be attached to the frame 300. The frame 300 may surround the stator 200. Both the stator 200 and the frame 300 are fixed.

[0045] The stator 200 may include a stator core 210 and a stator winding 220. The stator winding 220 may be positioned in an axial groove disposed on the inner surface of the stator core 210. The stator winding 220 may also include end portions 220A, 220B extending outward from opposite axial ends of the stator core 210.

[0046] The motor exciter 60 is positioned on the shaft 10 within the motor frame 300.

[0047] There is an air gap G between the inner periphery of the stator core 210 and the outer periphery of the rotor 100.

[0048] The frame 300 may include a cover 310 that covers the motor from the top. In this embodiment, bearings 20 and 30B are mounted on a base. Bearing housings 40 and 50B are supported on support blocks 340 and 350. Support blocks 340 and 350 may be supported on a floor in the field.

[0049] A first axial air passage may be formed between the outer periphery of the rotor 100 and the inner periphery of the stator 200. A second axial air passage may be formed between the outer periphery of the stator core 210 and the frame 300. The stator core 210 and the rotor 100 may have a laminated structure formed from a set of sheets.

[0050] In an embodiment of the present invention, the first bearing 20 located on the driving side of the motor and the second bearing 30B located on the non-driving side of the motor are both axial positioning sleeve bearings.

[0051] In an embodiment of the present invention, both the first bearing 20 and the second bearing 30B are axial positioning sleeve bearings. The axial clearance in one of the two axial positioning sleeve bearings 20 and 30B that restricts the axial movement of the shaft 10 is larger than the axial clearance in the other axial positioning sleeve bearing 20. This is such that during normal operation, the axial movement of the shaft 10 is restricted only by the first bearing 20, which has a smaller axial clearance. During abnormal events, the axial movement of the shaft 10 is restricted by both bearings 20 and 30B. The second bearing 30B, which has a larger axial clearance, reduces the axial load on the first bearing 20 during such abnormal events.

[0052] When the term “abnormal event” is used in this application, “abnormal event” means any unforeseen event or event that is not considered typical of the motor device that occurs near the motor device, such as an earthquake, seismic event, military explosion, rock blasting, piling, or other similar abnormal event that affects the motor device.

[0053] When the term “normal operation” is used in this application, “normal operation” means any normal operating condition that is not considered to fall under the term “abnormal event”.

[0054] In this application, the two axial positioning sleeve bearings 20 and 30B are sized such that, under normal operating conditions, the first bearing 20 with a smaller axial clearance restricts the axial movement of the shaft 10 as the axial positioning sleeve bearing 20, and both of the two axial positioning sleeve bearings 20 and 30B restrict the axial movement of the shaft 10 only when the initial threshold force of the "abnormal event" is reached.

[0055] Figure 2 An axial positioning sleeve bearing according to an embodiment of the present invention is shown.

[0056] Figure 1B The bearing on the drive side of the motor is an axial positioning sleeve bearing 20. The vertical center line YY of this bearing is shown in the attached figure.

[0057] Shaft 10 includes collars 12 and 13 extending radially outward from the outer surface of shaft 10. The collars 12 and 13 rotate with shaft 10. Shaft 10 also includes a portion 15 with a smaller diameter between the two collars 12 and 13. Bearing 20 includes a bearing frame 22. A spherical seat 21 is positioned within the bearing frame 22 between the collars 12 and 13. A sleeve 25 surrounding shaft 10 and forming a bearing surface between shaft 10 and bearing 20 is supported in the seat 21. Each collar 12 and 13 includes an outer radial surface and an inner radial surface. Bearing frame 22 includes a first bearing support 23 seated against the inner radial surface of collars 12 and 13. Bearing frame 22 also includes a second bearing support 24 seated against the outer radial surface of collars 12 and 13. Bearing frame 22 is supported within a bearing housing 40 (not shown in the figures). Shaft 10 is thus supported axially between bearing supports 23 and 24 within bearing frame 22. Shaft 10 is also rotatably supported in the radial direction by sleeve 25.

[0058] There is axial clearance between the rotating radial surfaces of the collars 12 and 13 of shaft 10 and the corresponding relatively stationary radial surfaces in bearing 20. This clearance allows for a small amount of axial movement of shaft 10. The maximum axial clearance of rotor 100 can be ±8 mm. Therefore, the axial movement of shaft 10 should be limited to less than this maximum clearance of ±8 mm under all circumstances.

[0059] Figure 3A shows a conventional sleeve bearing without axial positioning according to the prior art.

[0060] The bearing on the non-drive side of the motor in Figure 1A is a conventional sleeve bearing 30A. The vertical center line YY of this bearing is shown in the figure.

[0061] No collar is provided on the shaft 10 in the conventional sleeve bearing. The outer surface of the shaft 10 is straight, i.e., it has a uniform diameter within the region of the sleeve bearing 30A. The bearing 30A includes a bearing frame 32A. A spherical seat 31A is positioned within the bearing frame 32A. A sleeve 35A, surrounding the shaft 10 and forming the bearing surface between the shaft 10 and the bearing 30A, is supported in the seat 31A. The bearing frame 32A includes a first bearing support 33A, which forms the outermost portion of the bearing frame 32A. The bearing frame 32A is supported within a bearing housing 50A (not shown in the figures). Therefore, the shaft 10 is rotatably supported only in the radial direction by the sleeve 35A.

[0062] Figure 3B An axially locating sleeve bearing located on the non-driving side is shown according to an embodiment of the present invention.

[0063] Figure 1BThe bearing on the non-drive side of the motor is an axial positioning sleeve bearing 30B. The vertical center line YY of this bearing is shown in the attached drawing.

[0064] Shaft 10 includes collars 16 and 17 extending radially outward from the outer surface of shaft 10. The collars 16 and 17 rotate with shaft 10. Shaft 10 also includes a portion 18 with a smaller diameter between the two collars 16 and 17. Bearing 30B includes a bearing frame 32B. A spherical seat 31B is positioned within the bearing frame 32B between the collars 16 and 17. A sleeve 35B surrounding shaft 10 and forming a bearing surface between shaft 10 and bearing 30B is supported in the seat 31B. Each collar 16 and 17 includes an outer radial surface and an inner radial surface. Bearing frame 32B includes a first bearing support 33B seated against the inner radial surface of collars 16 and 17. Bearing frame 32B also includes a second bearing support 34B seated against the outer radial surface of collar 16. Bearing frame 32B is supported within a bearing housing 50B (not shown in the figures). Shaft 10 is therefore supported axially between bearing supports 33B and 34B in bearing frame 22. Shaft 10 is also rotatably supported radially by sleeve 35B.

[0065] Figure 4 A sleeve bearing mounted on a base for an electric motor according to an embodiment of the present invention is shown.

[0066] Bearing 20 includes an axial centerline XX and a vertical centerline YY.

[0067] A spherical seat 21 is seated within a bearing frame 22. A sleeve 25 is supported within the spherical seat 21. The spherical seat 21 and sleeve 25 may be provided with oil passages 29A and 29B for supplying oil from the oil chamber 26 to the bearing surface. The bearing 20 also includes two seals 27A and 27B, positioned on opposite axial sides of the sleeve 25 at an axial distance from each other. Each seal 27A and 27B abuts against the outer surface of the shaft 10. The seals 27A and 27B prevent bearing lubricant from seeping along the shaft 10 to the outside of the bearing 20.

[0068] Figure 5 A sleeve bearing mounted on a flange is shown for an electric motor according to an embodiment of the present invention.

[0069] Bearing 20 includes an axial centerline XX and a vertical centerline YY.

[0070] In this embodiment, the frame 22 of the bearing 20 is attached to the flange 70. A spherical seat 21 is seated in the bearing frame 22. A sleeve 25 is supported in the spherical seat 21. The spherical seat 21 and the sleeve 25 may be provided with an oil passage 29A for supplying oil from the oil chamber 26 to the bearing surface. The bearing 20 also includes two seals 27A and 27B, which are positioned on opposite axial sides of the sleeve 25 at an axial distance from each other. Each seal 27A and 27B acts against the outer surface of the shaft 10. The seals 27A and 27B prevent bearing lubricant from permeating along the shaft 10 to the outside of the bearing 20. A mechanical seal 28 is also provided to prevent air circulating in the motor from acting on the actual seals 27A and 27B.

[0071] The rotor core and stator core can have a laminated structure made of electrical steel sheets.

[0072] The present invention is not limited to the above examples, but may vary within the scope of the claims.

Claims

1. An electric motor, comprising: Shaft (10) Rotor (100), which is supported on the shaft (10), Stator (200) surrounding rotor (100). A frame (300) surrounds the stator (200). A first bearing (20) located at the drive end (D) of the motor and a second bearing (30B) located at the non-drive end (N) of the motor are used to rotatably support the shaft (10) on the frame (300), wherein the first bearing (20) and the second bearing (30B) are axial positioning sleeve bearings. Its features are, The axial clearance in the second bearing (30B) that restricts the axial movement of the shaft (10) is larger than the axial clearance in the first bearing (20), such that during normal operation, the axial movement of the shaft (10) is restricted only by the first bearing (20) with smaller axial clearance, and during abnormal events, the axial movement of the shaft (10) is restricted by both the first bearing (20) and the second bearing (30B), and the second bearing (30B) with larger axial clearance reduces the axial load on the first bearing (20) with smaller axial clearance; Each of the first bearing (20) and the second bearing (30B) includes: a sleeve bearing portion (21, 31B) that supports the shaft (10) only in the radial direction; and an axial bearing portion (23, 24, 33B, 34B) that includes a first bearing support (23, 33B) and a second bearing support (24, 34B), wherein the first bearing support (23, 33B) is seated against the inner radial surface of a collar extending radially outward from the outer surface of the shaft (10), and the second bearing support (24, 34B) is seated against the outer radial surface of the collar, such that the axial bearing portion (23, 24, 33B, 34B) supports the shaft (10) only in the axial direction.

2. The motor according to claim 1, wherein, The second bearing (30B), which has a large axial clearance, is sized to withstand approximately 50% of the axial impact load after the initial threshold force has been reached.

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