Motor with releasable bearing assembly

Abstract

A motor (10) includes a stator (12), a rotor (14), and a bearing assembly (16). The stator (12) includes a bearing shield assembly (24), the bearing shield assembly including a bearing shield (26) and a fixed labyrinth seal ring (28), the fixed labyrinth seal ring having a tortuous labyrinth surface. The rotor (14) includes a rotor shaft (32) and a rotatable labyrinth seal ring (34), the rotatable labyrinth seal ring having a tortuous labyrinth surface, the tortuous labyrinth surface of the rotatable labyrinth seal ring facing the tortuous labyrinth surface of the fixed labyrinth seal ring (28) at a first axial distance (D1). The bearing shield assembly (24) is provided with a fixed contact surface (40), and the rotor (14) further includes a relative contact surface (42), the relative contact surface axially facing the fixed contact surface (40) of the bearing shield assembly (24) at a second axial distance (D2), the second axial distance being shorter than the first axial distance (D1).

Description

Technical Field

[0001] The present invention relates to electric machines such as electric motors or generators. The invention particularly, but not exclusively, relates to electric motors for driving vehicles, in particular rail vehicles.

[0002] In principle, the invention can be applied to any electric machine. However, these benefits are particularly important in the case of permanent magnet excited electric machines, in which high magnetic forces are generated not only when the machine is powered, but also permanently. Background Art

[0003] An electric motor used to drive a vehicle typically includes a stator including a bearing shield and a stationary labyrinth seal ring; a rotor including a rotor shaft and a rotatable labyrinth seal ring mounted on the rotor shaft and facing the stationary labyrinth seal ring at a distance therefrom, thereby forming an annular labyrinth between the stationary labyrinth seal ring and the rotatable labyrinth seal ring. One or more bearing assemblies are releasably mounted between the bearing shield and the rotor shaft to guide rotational movement of the rotor about the axis of rotation and prevent axial movement of the rotor relative to the stator.

[0004] The bearings of electric motors are subject to extensive use and must be regularly repaired or replaced. Replacing bearings is relatively complex and involves the risk of damaging motor components. Typically, the rotor must be disassembled and then reassembled during the bearing replacement process. This can be a difficult task, especially in motors with permanent magnet excitation due to the high magnetic forces present in the air gap between the rotor and stator.

[0005] EP 2610514 proposes the construction of an electric motor in which labyrinth rings can be moved relative to each other until they contact each other in a locked position, so that the rotor can be fixed in the axial and radial directions for bearing replacement. The labyrinth rings have conical surfaces that contact each other in the locked position, so that a positive connection between the labyrinth rings can be achieved in the locked position, which ensures that the rotor is precisely fixed in the center of the axis of rotation. During normal operation of the motor, the fixed labyrinth ring is connected to the bearing shield by bolts. The purpose of loosening these bolts is to move the labyrinth ring to the locked position for bearing replacement. The fixed labyrinth ring can be fixed in this locked position by at least one locking bolt, preferably three locking bolts arranged at a certain angle. This ensures that the position of the motor is firmly fixed with relatively little labor during the bearing replacement process. In the maintenance position, the bearings of the motor can be quickly and easily repaired or replaced.

[0006] However, this solution has the disadvantage of being very weak, relying on a compressive load on the bolts to create a frictional engagement in the labyrinth, which provides only a reduced contact surface. Furthermore, grease is often present in the labyrinth, further reducing this frictional engagement. Furthermore, this solution is sensitive to the manner in which the locking bolts are tightened, and the bolts need to be tightened crosswise in small increments to prevent the rotor from seizing. Last but not least, this solution requires specialized labyrinth sealing rings. Summary of the Invention

[0007] The present invention aims to overcome at least some of the disadvantages of the prior art and to provide an electric machine that can be easily maintained.

[0008] According to a first aspect of the present invention, a motor is provided, comprising: a stator, a rotor, and a bearing assembly. The stator is provided with a bearing shield assembly, the bearing shield assembly comprising a bearing shield and a stationary labyrinth seal ring having a tortuous labyrinth surface. The rotor is rotatable about a rotation axis relative to the stator, and the rotor comprises a rotor shaft and a rotatable labyrinth seal ring mounted on the rotor shaft. The rotatable labyrinth seal ring has a tortuous labyrinth surface, the tortuous labyrinth surface of the rotatable labyrinth seal ring facing the tortuous labyrinth surface of the stationary labyrinth seal ring at a first axial distance from the tortuous labyrinth surface of the stationary labyrinth seal ring, so as to form an annular labyrinth between the tortuous labyrinth surface of the stationary labyrinth seal ring and the tortuous labyrinth surface of the rotatable labyrinth seal ring. The bearing assembly is releasably mounted between the bearing shield assembly and the rotor shaft for guiding the rotational movement of the rotor about the rotation axis. The bearing shroud assembly is provided with a stationary contact surface, and the rotor further comprises an opposing contact surface axially facing the stationary contact surface of the bearing shroud assembly at a second axial distance therefrom, the second axial distance being shorter than the first axial distance.

[0009] When the releasable bearing is released, it is possible to translate the rotor relative to the stator until the fixed contact surface reaches the counter contact surface, which occurs before the rotatable labyrinth ring contacts the stationary labyrinth sealing ring. The fixed contact surface and the counter contact surface provide large and clean surfaces for locking the rotor to the stator.

[0010] In an embodiment, the bearing assembly includes a bearing bushing, an outer race assembled into the bearing bushing, and an inner race assembled onto the rotor shaft. Preferably, the bearing bushing is provided with a mounting through-hole parallel to the rotational axis and aligned with the threaded hole of the bearing shield assembly. The bearing assembly includes a fastening bolt that is inserted into the mounting through-hole of the bearing bushing and screwed into the threaded hole of the bearing shield assembly to secure the bearing bushing to the bearing shield assembly. The fastening bolt can be loosened to remove the bearing assembly.

[0011] In an embodiment, the bearing bushing is supported on an outer surface of the bearing shield, and the stationary labyrinth seal ring is supported on an inner surface of the bearing shield opposite the outer surface.

[0012] In a preferred embodiment, the bearing bushing is provided with a clearance through-hole parallel to the axis of rotation and aligned with the through-hole of the bearing shield assembly. The clearance through-hole is capable of being aligned with the threaded hole of the rotor at an indexed angular position of the rotor relative to the stator. The clearance through-hole has a diameter greater than that of the through-hole of the bearing shield assembly and the threaded hole of the rotor, such that in this indexed angular position, a locking bolt can be inserted into the clearance through-hole and the through-hole of the bearing shield assembly and screwed into the threaded hole of the rotor, with the cylindrical bolt head of the locking bolt axially bearing against the edge of the through-hole of the bearing shield assembly. Once the bolt head of one of the locking bolts reaches the edge of the through-hole of the bearing shield assembly, subsequent tightening of the bolt causes the rotor to translate relative to the stator parallel to the bolt axis (i.e., parallel to the axis of rotation) until contact is established between a contact surface of the bearing shield assembly and an opposing contact surface of the rotor. This translation is guided by radial contact between the bolt shank and the inner wall of the through-hole of the bearing shield assembly. Once contact between the contact surfaces is established, the locking bolt is further tightened until the tension-loaded locking bolt provides sufficient pressure between the contact surfaces and the rotor is locked by frictional engagement of the contact surfaces.

[0013] In one embodiment, the thrust washer is releasably secured at the end of the rotor shaft so as to bear axially on the inner race of the bearing assembly.The opposite axial end of the inner race may bear against a shoulder or another axial stop of the rotor shaft.

[0014] In one embodiment, the bearing assembly includes rolling elements between the outer race and the inner race. The rolling elements may include spherical, cylindrical, tapered or barrel-shaped rollers arranged in one or more rows.

[0015] In one embodiment, an inner bearing space filled with lubricant is formed between the inner race and the outer race, and the inner bearing space is sealed by an annular labyrinth formed between the stationary labyrinth sealing ring and the rotatable labyrinth sealing ring. The lubricant is preferably grease.

[0016] In one embodiment, the outer bearing cap is releasably secured to the bearing shield assembly. The outer bearing cap can enclose an inner lubrication space of the bearing, which extends from the outer bearing cap to the labyrinth seal ring. The outer bearing preferably covers the mounting through-hole and / or clearance through-hole of the bearing bushing.

[0017] In one embodiment, the fixed contact surface is made of an electrically insulating material. Alternatively or additionally, the opposing contact surface is made of an electrically insulating material. This ensures that no current flows through the contact surfaces when they are in contact.

[0018] In one embodiment, the fixed contact surface is made integrally with the fixed labyrinth seal ring. Alternatively, the fixed contact surface is formed on the bearing shield.

[0019] In a preferred embodiment, the fixed contact surface comprises at least one flat portion facing the flat portion of the opposing contact surface at the second axial distance.

[0020] Advantageously, the stationary labyrinth sealing ring and the rotatable labyrinth sealing ring are provided with staggered tubular ribs aligned with the axis of rotation, the labyrinth being formed by continuous annular spaces between the staggered tubular ribs.

[0021] In an embodiment, the electric machine is a drive motor of a rail vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Other advantages and features of the invention will become more clearly apparent from the following description of particular embodiments of the invention given purely as non-limiting examples and represented in the accompanying drawings, in which:

[0023] - FIG1 is an isometric view of a motor according to an embodiment of the invention, as seen from the drive side;

[0024] - FIG2 is an isometric view of the motor of FIG1 as viewed from the non-drive side during the step of disassembling the first bearing assembly on the non-drive side of the motor;

[0025] - Figure 3 is a front view of the motor of Figure 1 as viewed from the non-drive side, without the outer bearing cap;

[0026] - Figure 4 1 is an axial cross-sectional view of the motor through the cross-sectional plane IV-IV shown in FIG3;

[0027] - Figure 5 is an axial cross-sectional view of the motor of FIG. 1 through the cross-sectional plane VV shown in FIG. 3 ;

[0028] - Figure 6 shows a detail of the electric machine of FIG. 1 in the section plane VV shown in FIG. 3 during the step of disassembling the first bearing assembly on the non-drive side of the electric machine;

[0029] - Figure 7 shows a detail of the motor of FIG. 1 in the section plane VV shown in FIG. 3 during a further step of disassembling the first bearing assembly on the non-drive side of the motor;

[0030] - Figure 8 The motor in Figure 1 is shown Figure 7 Detail of the section plane IV-IV shown in FIG3 during the disassembly step;

[0031] - Figure 9 shows a detail of the electric machine of FIG. 1 in the section plane VV shown in FIG. 3 during the step of disassembling the second bearing assembly on the drive side of the electric machine;

[0032] - Figure 10 The electric machine of FIG. 1 is shown in detail in the section plane VV shown in FIG. 3 during a further step of disassembling the second bearing assembly on the drive side of the electric machine.

[0033] Corresponding reference numerals designate like or corresponding parts throughout the several views. DETAILED DESCRIPTION

[0034] Refer to Figures 1 to Figure 5 The motor 10 (e.g., a drive motor for a rail vehicle) includes a stator 12, a rotor 14, a first bearing assembly 16 at a non-driven end of the motor 10, and a second bearing assembly 116 at a driven end of the motor 10. The first bearing assembly 16 and the second bearing assembly 116 are used to guide the rotational movement of the rotor 14 relative to the stator 12 around the rotation axis 100 of the motor 10.

[0035] The stator 12 is provided with stator windings 18 housed in a stator housing 20, which includes a stator frame 22, a first bearing shield assembly 24 at the non-drive end of the motor 10, and a second bearing shield assembly 124 at the drive end of the motor 10. The first bearing shield assembly 24 is annular and includes a bearing shield 26 and a stationary labyrinth seal ring 28. The second bearing shield assembly 124 is annular and includes a bearing shield 126 and two stationary labyrinth seal rings 128, 228.

[0036] The rotor 14 is centered about an axis of rotation 100 and includes a set of rotor windings or permanent magnets 30, a rotor shaft 32, a first rotatable labyrinth seal ring 34 mounted on the rotor shaft 32 and facing the stationary labyrinth seal ring 28 of the first bearing shield assembly 24, and a pair of second rotatable labyrinth seal rings 134, 234 mounted on the rotor shaft 32 and facing the two stationary labyrinth seal rings 128, 228 of the second bearing shield assembly 124. The stationary labyrinth seal ring 28 , 128 , 228 and the rotatable labyrinth seal ring 34 , 134 , 234 are provided with staggered tubular ribs 36 , 38 , 136 , 138 , 236 , 238 aligned with the rotation axis 100 , and the tortuous path is formed by the continuous annular spaces between the staggered tubular ribs 36 , 38 , 136 , 138 , 236 , 238 .

[0037] In an axial direction parallel to the rotation axis 100 , a minimum distance D1 separates the tortuous labyrinth surface formed by the tubular ribs 38 of the rotatable labyrinth seal ring 34 from the tortuous labyrinth surface formed by the tubular ribs 36 of the stationary labyrinth seal ring 28 .

[0038] It is noteworthy that the bearing shield assembly 24 is provided with one or more fixed contact surfaces 40, and the rotor 14 further includes one or more opposing contact surfaces 42, the opposing contact surfaces 42 axially facing the fixed contact surface 40 of the bearing shield assembly 24 at an axial distance D2 from the fixed contact surface of the bearing shield assembly, where D2 < D1. The fixed contact surface and the opposing contact surface are flat surfaces perpendicular to the axis of rotation.

[0039] A minimum distance D11 separates the tortuous labyrinth surface formed by the tubular ribs 138, 238 of the rotatable labyrinth seal ring 134, 234 from the tortuous labyrinth surface formed by the tubular ribs 136, 138 of the stationary labyrinth seal ring 128, 228 in an axial direction parallel to the rotation axis 100. D11 is such that D2 < D11 and preferably D11 is equal to D1.

[0040] Similarly, the bearing shield assembly 124 is provided with one or more stationary contact surfaces 140, and the rotor 14 further includes one or more opposing contact surfaces 142, which face the stationary contact surface 140 of the bearing shield assembly 124 axially at an axial distance D22 from the stationary contact surface of the bearing shield assembly, where D12 < D11. The stationary contact surface and the opposing contact surface are flat surfaces perpendicular to the axis of rotation. Preferably, D12 is equal to D2.

[0041] A first bearing assembly 16 at the non-drive end of the motor 10 is mounted between the first bearing shield assembly 24 and the rotor 14 , and a second bearing assembly 116 is mounted between the second bearing shield assembly 124 and the rotor 14 for guiding rotational movement of the rotor 14 about the rotational axis 100 .

[0042] More specifically, the first bearing assembly 16 includes a bearing sleeve 44, an outer race 46 press-fitted into the bearing sleeve 44, an inner race 48 press-fitted onto the rotor shaft 14, and rolling elements 50 between the inner race 48 and the outer race 46. In this embodiment, the rolling elements 50 are spheres, and the inner race 48 and the outer race 46 have concave cross-sections. The inner race 48 is axially supported on a shoulder 52 on the rotor shaft 14. A thrust washer 54 is releasably secured to an end 56 of the rotor shaft 32 by bolts 58 so as to be axially supported on the inner race 48 of the bearing assembly 16.

[0043] like Figure 4As depicted in FIG, the bearing bushing 44 is axially supported on the outer side 60 of the bearing shield 26 and is provided with a set of several, preferably three or more, mounting through-holes 62 distributed on the circumference of the bearing bushing 44 and extending in a direction parallel to the rotation axis 100. The mounting through-holes 62 are aligned with the central hole 64 of the bearing shield 26 and the threaded holes 65 that fix the labyrinth seal ring 28. Fastening bolts 66 are inserted into the mounting through-holes 62 of the bearing bushing and are screwed into the threaded holes 64 of the bearing shield 26 to fasten the bearing bushing 44 to the bearing shield 26.

[0044] like Figure 5 As shown, the bearing bushing 44 is further provided with a group of several, preferably three or more, clearance through holes 68 distributed on the circumference of the bearing bushing 44, the clearance through holes 68 being parallel to the rotation axis 100 and aligned with the through holes 70, 72 of the bearing shield assembly 24. In this embodiment, the clearance through holes 68 pass through the bearing shield 26 and the fixed labyrinth sealing ring 28.

[0045] These clearance holes 68 align with the threaded holes 74 of the rotor 14 when the rotor 14 is in the indexed angular position relative to the stator 12. The clearance holes 68 have a diameter greater than the diameters of the bearing shield assembly through holes 70, 72 and the rotor threaded holes 74.

[0046] An outer bearing cap 76 is releasably secured to the bearing shield 26 by bolts 78 and covers the mounting through-holes 62 and the clearance through-holes 68 of the bearing bushing 44. A sealed lubrication volume 80 is formed between the inner race 48 and the outer race 46, which is closed at one axial end by the outer bearing cap 76 and sealed at the opposite axial end by a labyrinth seal formed by the stationary labyrinth seal ring 28 and the rotatable labyrinth seal ring 34. The lubrication volume may be filled with a lubricant, preferably grease.

[0047] Similarly, the second bearing assembly 16 at the drive end of the motor includes a bearing sleeve 144 integral with a fixed labyrinth seal ring 228, an outer race 146 press-fit into the bearing sleeve 144, an inner race 148 press-fit onto the rotor shaft 14, and rolling elements 150 between the inner race 148 and the outer race 146. In this embodiment, the rolling elements are cylindrical rollers, and the rings of the inner race 148 and the outer race 46 are cylindrical. The inner race 148 is axially supported on a shoulder 152 on the rotor shaft 14.

[0048] like Figure 4As depicted in FIG, the bearing bushing 144 is axially supported on the outer side 160 of the bearing shield 126 and is provided with a plurality of, preferably three or more, mounting through-holes 162 distributed around the circumference of the bearing bushing 144 and extending in a direction parallel to the rotation axis 100. The mounting through-holes 162 are aligned with the central through-holes of the bearing shield 126 and the threaded holes 165 that secure the labyrinth seal ring 128. Fastening bolts 166 are inserted into the mounting through-holes 162 of the bearing bushing 144 and screwed into the threaded holes 164 of the bearing shield 126 to fasten the bearing bushing 144 to the bearing shield 126.

[0049] like Figure 5 As shown, the bearing bushing 144 is further provided with a plurality of, preferably three or more, clearance holes 168 distributed around the circumference of the bearing bushing 144. The clearance holes 168 are parallel to the rotational axis 100 and aligned with the through holes 170, 172 of the bearing shield assembly 124. In this embodiment, the clearance holes 16 extend through the bearing shield 126 and the stationary labyrinth seal ring 128. When the rotor 14 is in an indexed angular position relative to the stator 12, these clearance holes 168 can be aligned with the threaded holes 174 of the rotor 14. The diameter of the clearance holes 168 is larger than the diameters of the through holes 170, 172 of the bearing shield assembly and the threaded hole 174 of the rotor.

[0050] A sealed lubrication volume 180 is formed between the inner race 48 and the outer race 46, which is sealed at one axial end by a labyrinth seal formed by a stationary labyrinth seal ring 128 and a rotatable labyrinth seal ring 134, and at the opposite axial end by a labyrinth seal formed by a stationary labyrinth seal ring 228 integral with the bearing bushing 144 and a rotatable labyrinth seal ring 34. The lubrication volume can be filled with a lubricant, preferably grease.

[0051] To disassemble the first bearing assembly 16 at the non-drive end of the motor 10 , the bolts 78 must first be loosened and the outer bearing cap 76 removed, which provides access to the clearance through-holes 68 and the mounting through-holes 62 of the bearing bushing 44 .

[0052] The rotor 14 is rotated to the indexed angular position and the locking bolt 82 is inserted into the clearance through-hole 68 (see FIG. 2 ) and the through-holes 70 , 72 of the bearing shield assembly 24 . Figure 6 As shown, the locking screw 82 is screwed into the threaded hole 74 of the rotor 14 until the cylindrical screw head 84 of the locking screw 82 bears axially against the edge 86 of the through-hole 70 of the bearing shield 26 .

[0053] Once the bolt head 84 of the locking bolt 82 reaches the edge 86 of the through hole 70 of the bearing shield 26, the shank of the locking bolt 82 comes into contact with the inner walls of the through holes 70, 72 of the bearing shield 24 and the fixed labyrinth seal 28 and ensures the central positioning of the rotor 14 relative to the rotation axis 10 independently of the bearing assembly 16. Thus, the mounting bolt 66 can be at least partially unscrewed to allow limited translational movement of the rotor 14 relative to the stator 12.

[0054] like Figure 7 As shown, tightening the locking bolt 82 subsequently causes the rotor 14 to translate relative to the stator 12 parallel to the locking bolt axis (i.e., parallel to the rotational axis 100) until contact is established between the contact surface 40 of the bearing shield assembly 24 and the opposing contact surface 42 of the rotor 14. This translation is guided by radial contact between the shank of the locking bolt 82 and the inner walls of the through-holes 70, 72 of the bearing shield assembly 24 and / or by the rolling elements 50 and the inner race 48. Once contact between the contact surfaces 40, 42 is established, the locking bolt 82 is further tightened until the tension-loaded locking bolt 82 provides sufficient pressure between the contact surfaces 40, 42 and the rotor 14 is locked by frictional engagement of the contact surfaces 40, 42. Notably, because D2 < D1, no contact occurs between the interleaved ribs 36, 38 of the stationary and movable labyrinth seal rings. Similarly, because D2 < D11, no contact occurs between the interleaved ribs 136, 138, 236, 238 of the stationary labyrinth seal rings 128, 228 and the movable labyrinth seal rings 134, 234. The cylindrical rollers 150 slide on the turns of the inner race 148 during translational motion of the rotor.

[0055] If they are Figure 5 If the ring puller is not completely removed at the end of the step, the mounting bolts 66 can be completely unscrewed and removed together with the bolts 58. The bearing bushing 76, the outer race 46 and the rolling elements 50 can be removed before the ring puller is inserted to reach the distal end face of the inner race 48 and pulls the inner race 48.

[0056] like Figure 9 As shown, in order to disassemble the second bearing assembly 116 at the drive end of the motor 10, it is first necessary to loosen the bolts 78 at the non-drive end of the motor 10 and remove the outer bearing cover 76, which provides access to the clearance through hole 68 of the bearing bushing 44 and the mounting through hole 62 of the bearing bushing 44.

[0057] like Figure 9 As shown, the rotor 14 is rotated to the indexed position and, optionally, a threaded indexing rod 90 is inserted into the clearance through-hole 68 and the through-holes 70 , 72 of the bearing shield assembly 24 and threaded into the threaded bore 74 of the rotor 14 .

[0058] Once the indexing rod 90 is in position, the shank of the indexing rod 90 contacts the inner walls of the through-holes 70, 72 of the bearing shield 24 and the fixed labyrinth seal 28 and ensures the central positioning of the rotor 14 relative to the axis of rotation 10, independently of the bearing assembly 16. Thus, the mounting bolts 66 can be at least partially unscrewed to allow limited translational movement of the rotor 14 relative to the stator 12.

[0059] Once these preliminary steps have been completed at the non-driven end of the motor 10, the actual operation at the driven end can begin. Figure 9 As shown, the locking bolt 182 is inserted into the clearance through-hole 168 and the through-holes 170 , 172 of the bearing shield assembly 124 , and screwed into the threaded hole 174 of the rotor 14 until the cylindrical bolt head 184 of the locking bolt 182 axially supports the edge 186 of the through-hole 170 of the bearing shield 126 .

[0060] Once the bolt head 184 of the locking bolt 182 has reached the edge 186 of the through hole 170 of the bearing shield 126, the shank of the locking bolt 182 comes into contact with the inner walls of the through holes 170, 172 of the bearing shield 124 and the stationary labyrinth seal 128 and ensures the central positioning of the rotor 14 relative to the rotation axis 10 independently of the bearing assembly 116. Thus, the mounting bolt 166 can be at least partially unscrewed to allow limited translational movement of the rotor 14 relative to the stator 12.

[0061] like Figure 10 As shown, subsequent tightening of the locking bolt 182 causes translational movement of the rotor 14 relative to the stator 12 parallel to the locking bolt axis (i.e., parallel to the rotational axis 100) until contact is established between the contact surface 140 of the bearing shield assembly 124 and the opposing contact surface 142 of the rotor 14. This translation is guided by radial contact between the shank of the locking bolt 182 and the inner walls of the through-holes 170, 172 of the bearing shield assembly 124 and / or by the rolling elements 150 and the inner race 148. Once contact between the contact surfaces 140, 142 is established, the locking bolt 182 is further tightened until the tension-loaded locking bolt 182 provides sufficient pressure between the contact surfaces 140, 142 and the rotor 14 is locked by frictional engagement of the contact surfaces 140, 142. It is noteworthy that, because D12 < D11, no contact occurs between the staggered ribs 136, 138, 236, 238 of the stationary labyrinth seal rings 128, 228 and the movable labyrinth seal rings 134, 234. It is noteworthy that the bearing assembly 16 at the non-drive end of the motor 10 moves with the rotor 14 and thrust washer 54 and pushes the stationary labyrinth seal ring 28 away from the bearing shield 26, while the relative angular position between the two components is maintained by the indexing rod 90. Figure 9 As shown, the movable labyrinth seal ring 223 can then be pulled out and the bearing bushing 176 , outer race 146 and rolling elements 150 can be removed before a ring puller is inserted to reach the distal end face of the inner race 148 and pull the inner race 148 .

[0062] The bearing shield 26, 126 is preferably metallic.The stationary labyrinth seal ring 28, 128, 228 is preferably made of an electrically insulating material so that no electrical path is created when the contact surfaces 40, 42, 140, 142 contact each other.

[0063] As a variation, Figure 4 After the step of, subsequently tightening the locking bolts 82 may result in elastic deformation of the bearing shield 26, which results in contact between the contact surfaces 40, 42 without requiring translation of the rotor 14 relative to the stator 12. Alternatively, deformation of the rotor plate where the threaded holes 74 are located may occur.

[0064] A clearance may be maintained between the shank of the locking bolt 82 , the through-holes 70 , 72 of the bearing shield 24 , and the stationary labyrinth seal 28 , in which case centering of the rotor 14 relative to the axis of rotation 10 is provided by the bearing assembly 16 when the mounting bolts 66 are removed.

Claims

1. A motor (10), comprising: - a stator (12), the stator (12) comprising a bearing shield assembly (24, 124), the bearing shield assembly (24, 124) comprising a bearing shield (26, 126) and a stationary labyrinth seal ring (28, 128), the stationary labyrinth seal ring (28, 128) having a tortuous labyrinth surface, - a rotor (14) rotatable relative to the stator (12) about a rotation axis (100), the rotor (14) comprising a rotor shaft (32) and a rotatable labyrinth seal ring (34, 134), the rotatable labyrinth seal ring (34, 134) being mounted on the rotor shaft (32), the rotatable labyrinth seal ring (34, 134) having a meandering labyrinth surface, the meandering labyrinth surface of the rotatable labyrinth seal ring (34, 134) facing the stator at a first minimum axial distance (D1, D11) from the meandering labyrinth surface of the stationary labyrinth seal ring (28, 128) the tortuous labyrinth surface of the stationary labyrinth seal ring (28, 128) so as to form an annular labyrinth between the tortuous labyrinth surface of the stationary labyrinth seal ring (28, 128) and the tortuous labyrinth surface of the rotatable labyrinth seal ring (34, 134), wherein the stationary labyrinth seal ring (28, 128) and the rotatable labyrinth seal ring (34, 134) are provided with staggered tubular ribs (36, 38, 136, 138) aligned with the rotation axis (100), the labyrinth being formed by continuous annular spaces between the staggered tubular ribs (36, 38, 136, 138), and a bearing assembly (16, 116) releasably mounted between the bearing shield assembly (24, 124) and the rotor shaft (32) for guiding rotational movement of the rotor (14) relative to the stator (12) about the rotational axis (100), Characterized in that the bearing shield assembly (24, 124) is provided with a fixed contact surface (40, 140), and the rotor (14) further includes an opposing contact surface (42, 142), the opposing contact surface axially facing the fixed contact surface (40, 140) of the bearing shield assembly (24, 124) at a second axial distance (D2, D12) from the fixed contact surface (40, 140) of the bearing shield assembly (24, 124), the second axial distance (D2, D12) being shorter than the first minimum axial distance (D1, D11).

2. The electric machine (10) according to claim 1, wherein The bearing assembly (16, 116) includes a bearing sleeve (44, 144), an outer race (46, 146), and an inner race (48, 148), the outer race being mounted in the bearing sleeve (44, 144) and the inner race being mounted on the rotor shaft (32).

3. The electric machine (10) according to claim 2, wherein The bearing sleeve (44, 144) is provided with a mounting through hole (62, 162), which is parallel to the rotation axis (100) and aligned with the threaded hole (65, 165) of the bearing shield assembly (24, 124); the bearing assembly (16, 116) includes a fastening bolt (66, 166), which is inserted into the mounting through hole (62, 162) of the bearing sleeve (44, 144) and screwed into the threaded hole (65, 165) of the bearing shield assembly (24, 124) to fasten the bearing sleeve (44, 144) to the bearing shield assembly (24, 124).

4. The electric machine (10) according to any one of claims 2 to 3, wherein: The bearing bushing (44, 144) is provided with a clearance through hole (68, 168), the clearance through hole (68, 168) is parallel to the rotation axis (100) and aligned with the through hole (70, 72, 170, 172) of the bearing shield assembly (24, 124), and the clearance through hole (68, 168) is capable of being aligned with the threaded hole (74, 174) of the rotor (14) at an indexing angle position of the rotor (14) relative to the stator (12), and the diameter of the clearance through hole (68, 168) is larger than the through hole (70, 72, 170, 172) of the bearing shield assembly. 170, 172) and the threaded hole (74, 174) of the rotor (14), so that at the indexing angle position, a locking bolt (82, 182) can be inserted into the clearance through hole (68, 168) and the through hole (70, 72, 170, 172) of the bearing shield assembly (24, 124) and screwed into the threaded hole (74, 174) of the rotor (14), wherein the cylindrical bolt head (84) of the locking bolt (82) is axially supported on the edge of the through hole (70, 72, 170, 172) of the bearing shield assembly (24).

5. The electric machine (10) of any one of claims 2 to 3, further comprising a thrust washer (54) releasably secured at an end of the rotor shaft (32) to axially support the inner race (48) of the bearing assembly (16).

6. The electric machine (10) according to any one of claims 2 to 3, wherein: The bearing assembly (10) includes rolling elements (50, 150) located between the outer race (46, 146) and the inner race (48, 148).

7. The electric machine (10) according to any one of claims 2 to 3, wherein: An inner bearing space (80, 180) filled with lubricant is formed between the inner race (48, 148) and the outer race (50, 150), and the inner bearing space (80, 180) is sealed by the annular labyrinth formed between the stationary labyrinth seal ring (28, 128) and the rotatable labyrinth seal ring (34, 134).

8. The electric machine (10) of any one of claims 2-3, further comprising an outer bearing cap (76) releasably secured to the bearing shield assembly (24).

9. The electric machine (10) according to any one of claims 1 to 3, wherein: The fixed contact surface (40, 140) is made of an electrically insulating material.

10. The electric machine (10) according to any one of claims 1 to 3, wherein: The opposing contact surfaces (42, 142) are made of electrically insulating material.

11. The electric machine according to any one of claims 1 to 3, wherein: The fixed contact surface (40, 140) and the fixed labyrinth seal ring (28, 128) are made integrally.

12. The electric machine according to any one of claims 1 to 3, wherein: The fixed contact surface (40, 140) is formed on the bearing shield (26, 126).

13. The electric machine (10) according to any one of claims 1 to 3, wherein: The fixed contact surface (40, 140) includes at least one flat portion, the flat portion facing the flat portion of the opposing contact surface (42, 142) at the second axial distance.

14. The electric machine (10) according to any one of claims 1 to 3, wherein: The electric motor (10) is a drive motor of a rail vehicle.

Images