Method for mounting an electric machine and its transport support

Abstract

The electric machine includes a stator (101), a rotor (102), and bearings (103) configured to rotatably support the rotor relative to the stator. The electric machine includes a force-generating device (104) attached to the stator and including an actuator (105) for directing an axial force at the end of the rotor's shaft (106). The actuator can be hydraulic, pneumatic, or electrically driven. While the electric machine is being transported, for example, by using a trailer, truck, locomotive, or ship, and transportation support is required, the actuator is controlled to direct an axial force at the end of the shaft to remove clearance from the bearing and thereby protect the bearing against damage during transportation. While the electric machine is being used for its intended purpose as a motor or generator, there is advantageously a physical air gap between the actuator and the end of the shaft.

Description

[Technical Field]

[0001] The present disclosure relates generally to electric machines. More particularly, the present disclosure relates to an electric machine including a stator, a rotor, bearings configured to rotatably support the rotor relative to the stator, and means for mounting a transport support to protect the electric machine against damage when the electric machine is transported or otherwise subjected to external vibrations and / or shocks while stationary. Additionally, the present disclosure relates to a method for mounting a transport support for an electric machine. Furthermore, the present disclosure relates to an electric drive. [Background technology]

[0002] The bearings of an electric machine can be damaged when the machine is stopped and transported by trailer, truck, locomotive, or ship, either directly or as part of an application system such as a work machine. Particularly in large electric machines with relatively large rotors, the bearings are at serious risk of being damaged by external vibrations and shocks if not properly protected. Damage can occur because all rolling bearings have clearances that allow them to be lubricated and to rotate with low rolling resistance. Therefore, external vibrations and shocks can cause bearing surfaces to collide with each other, resulting in damage.

[0003] To avoid bearing damage as described above, the rotor of the electric machine must be mechanically supported so that the bearing surfaces do not collide with each other when the electric machine is transported or otherwise subjected to external vibrations and / or shocks while stationary. Arranging sufficient mechanical support can be particularly difficult when the electric machine is part of an application system, such as a work machine, that is being transported or otherwise subjected to external vibrations and / or shocks. Summary of the Invention [Means for solving the problem]

[0004] The following presents a simplified summary in order to provide a basic understanding of some aspects of various embodiments. This summary is not an extensive overview of the invention. It is not intended to identify key or critical elements of the invention, nor is it intended to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to a more detailed description of example embodiments.

[0005] In accordance with the present invention, - a stator; - a rotor rotatably supported relative to the stator and configured to electromagnetically interact with the stator to generate torque in response to one or more currents supplied to the electric machine; - a bearing configured to rotatably support the rotor relative to the stator; a force generating device including an actuator mechanically attached to the stator and configured to direct an axial force at an end of the rotor shaft to remove clearance from the bearing; A novel electric machine is provided that includes:

[0006] While the electric machine is being transported or otherwise subjected to external vibrations and / or shocks while at rest, the actuator is controlled to direct an axial force at the end of the shaft to remove clearance from the bearing and thereby prevent the bearing surfaces from colliding with each other, protecting the bearing against damage. While the electric machine is used for its purpose as a motor or generator, the force generating device is advantageously in a mode where there is a physical air gap between the actuator and the end of the shaft.

[0007] In the electric machines described above, the fact that many bearings that provide radial support can also withstand axial loads is utilized to support the rotor when the electric machine is being transported or otherwise subjected to external vibrations and / or shocks while at rest. For example, round or convex rolling elements naturally eliminate radial clearance when the outer ring of the bearing is axially displaced from the inner ring of the bearing.

[0008] The force-generating device can be a hydraulic device in which the actuator includes a hydraulic piston. The force-generating device can also be a pneumatic device with a pneumatically driven actuator or an electric device with a magnetically driven actuator. It should be noted that embodiments of the present invention are not limited to any particular method or methods for directing an axial force at the end of the shaft of the electric machine.

[0009] In accordance with the present invention, there is also provided a novel electric drive including an electric machine and a converter configured to drive the electric machine. The electric machine includes a state detection device configured to generate a state signal indicative of whether an actuator is directing an axial force at an end of the rotor shaft. The converter is configured to receive the state signal and to withhold supply of voltage to the electric machine when the actuator is directing an axial force at the end of the rotor shaft, thereby avoiding unintended start-up and possible damage to the electric machine when the force-generating device is operating.

[0010] According to the invention there is provided an electric machine comprising: - a stator; a rotor rotatably supported relative to the stator and configured to electromagnetically interact with the stator to generate torque in response to current supplied to the electric machine; a bearing configured to rotatably support the rotor relative to the stator; A novel method of mounting a support for transporting an electric machine is also provided, which includes:

[0011] A method according to the present invention includes directing an axial force at the end of the rotor shaft to remove clearance from the bearing using a force generating device including an actuator mechanically attached to the stator and configured to direct an axial force at the end of the rotor shaft.

[0012] In this specification, the term "transport support" refers to a support arrangement that can be applied to protect against damage not only during transport but also during other situations in which the electric machine is at rest and is subjected to external vibrations and / or shocks.

[0013] Exemplary and non-limiting embodiments are set forth in the accompanying dependent claims.

[0014] The illustrative and non-limiting embodiments, both as to structure and method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific illustrative and non-limiting embodiments when read in conjunction with the accompanying drawings.

[0015] The verbs "comprise" and "include" are used herein as open limitations that do not exclude or require the presence of unrecited features.

[0016] The features recited in the dependent claims may be freely combined with one another, unless expressly stated otherwise.

[0017] Furthermore, it is to be understood that the use of "a" or "an", i.e. the singular, does not exclude the plural throughout this specification.

[0018] Exemplary, non-limiting embodiments and their advantages are described in more detail below, by way of example and with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0019] [Figure 1] 1 illustrates an electric machine in accordance with an exemplary and non-limiting embodiment. [Figure 2] 1 illustrates an electric machine in accordance with an exemplary and non-limiting embodiment. [Figure 3] 1 illustrates a flowchart of a method for implementing a support for transporting an electric machine, according to an exemplary and non-limiting embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] The specific examples provided herein below are not to be construed as limitations on the scope and / or applicability of the appended claims. The listings and groups of examples provided herein are not intended to be exhaustive unless expressly stated to the contrary.

[0021] FIG. 1 illustrates a portion of an electric machine 100 according to an exemplary and non-limiting embodiment. The electric machine 100 includes a stator 101 and a rotor 102 rotatably supported relative to the stator 101 and configured to electromagnetically interact with the stator to generate torque in response to current supplied to the electric machine. The electric machine 100 may be, for example, an induction machine, a permanent magnet machine, a reluctance machine, or a direct current (DC) machine. In FIG. 1 , only the non-drive (ND) end of the electric machine 100 is shown. The stator 101 is shown in cross section with a geometric cross-sectional plane parallel to the yz-plane of a coordinate system 199. The stator 102 includes a stator core structure 118 and stator windings 119. An axial direction of the electric machine 100 is parallel to the z-axis of the coordinate system 199. The electric machine 100 includes bearings configured to rotatably support the rotor 102 relative to the stator 101. In Figure 1, the ND-end bearing is designated by reference numeral 103. In this exemplary case, bearing 103 is a ball bearing. Correspondingly, the drive "D"-end bearing of electric machine 100 may be a ball bearing. The D-end bearing is not shown in Figure 1.

[0022] The electric machine 100 includes a force-generating device 104 mechanically attached to the stator 101 and includes an actuator 105 configured to direct an axial force at the end of the shaft 106 of the rotor 102 to remove clearance from the bearings of the electric machine 100. In FIG. 1 , the end of the shaft 106 is shown in cross section with the geometric cross-sectional plane parallel to the yz-plane of the coordinate system 199. In this illustrative case, the force-generating device is at the ND-end of the electric machine. However, the force-generating device could also be configured to direct an axial force at the end of the shaft at the D-end of the electric machine. For example, a gear or sheave could be attached to the end of the shaft of the electric machine, and the force-generating device configured to direct an axial force at the end of the shaft that protrudes through the gear or sheave.

[0023] In the exemplary electric machine 100 illustrated in FIG. 1 , the force-generating device 104 is a hydraulic device including a hydraulic cylinder 107, and the actuator 105 of the force-generating device 104 includes a hydraulic piston 108. In FIG. 1 , the hydraulic cylinder 107 is shown in cross section with a geometric cross-sectional plane parallel to the yz-plane of a coordinate system 199. In this exemplary case, the hydraulic cylinder 107 is a single-acting hydraulic cylinder capable of pushing the hydraulic piston 108 in the negative z-direction of the coordinate system 199 toward the end of the rotor shaft 106. The force-generating device 104 includes a return spring 109 configured to push the hydraulic piston in the positive z-direction of the coordinate system 199, away from the end of the rotor shaft 106. The force-generating device of the electric machine, according to one exemplary and non-limiting embodiment, can also be an electromagnetic device including an electromagnet for generating an axial force directed toward the end of the electric machine shaft. Furthermore, the force generating device of the electric machine according to one exemplary and non-limiting embodiment can be a pneumatic device including a pneumatically driven actuator for generating an axial force directed at the end of the shaft of the electric machine.

[0024] In the exemplary electric machine 100 illustrated in FIG. 1 , the force-generating device 104 includes a pressurizer 110 that can maintain hydraulic fluid pressure without external energy, for example, when the electric machine 100 is being transported or otherwise subject to external vibration and / or shock and external energy is unavailable. In this exemplary case, the pressurizer 110 includes a body and a flexible bag 120 containing hydraulic fluid within the body. The force-generating device 104 is activated by forcing compressed flexible material 111, such as air or other gas, into the space between the body and the flexible bag 120. The flexible material 111 transfers pressure to the flexible bag 120, thereby maintaining the pressure of the hydraulic fluid. The force-generating device 104 is deactivated by releasing the pressure in the flexible material 111. Depending on the requirements and the availability or unavailability of external energy, various means for controlling the force-generating device 104 are possible, such as an electrically driven hydraulic pump, a spring-activated pressurizer, etc.

[0025] 1, the force-generating device 104 includes a collar portion 112 attached to a bearing shield 113 of the electric machine 100 and a flange portion 114 connected to the collar portion. In FIG. 1, the collar portion 112 and flange portion 114 are shown in cross section with the geometric cross-sectional plane parallel to the yz-plane of coordinate system 199. A hydraulic cylinder 107 is attached to the flange portion 114, and an actuator 105 protrudes through an aperture in the flange portion 114 toward the end of the rotor shaft 106.

[0026] The exemplary electric machine 100 illustrated in Figure 1 includes a protective element 117 between the actuator 105 of the force-generating device 104 and the end of the rotor shaft 106. In Figure 1, the protective element 117 is shown in a cross-sectional view with a geometric cross-sectional plane parallel to the yz-plane of the coordinate system 199. The protective element 117 is made of a material that is softer than the material of the rotor shaft 106 and protects the rotor shaft from shape deformation. The protective element 117 may be made of aluminum or nylon, for example.

[0027] According to one exemplary, non-limiting embodiment, the electric machine includes a state detection device 115 configured to generate a state signal 116 that directly or indirectly indicates whether the actuator 105 is directing an axial force at the end of the shaft 106 of the rotor 102. In the exemplary electric machine illustrated in FIG. 1 , the state detection device 115 includes a pressure sensor configured to detect the pressure of the hydraulic fluid and generate the state signal 116 according to the detected pressure. According to one exemplary, non-limiting embodiment, the state detection device of the electric machine may also include a position sensor configured to detect the axial position of the actuator of the force-generating device or a mechanical sensor such as a strain gauge configured to detect mechanical stress or deformation of the actuator or some other relevant part of the force-generating device. In the exemplary case where the force-generating device is an electromagnetic force-generating device, the state detection device may include a device for generating the state signal based on current flow in the electromagnetic force-generating device. In the exemplary case where the force-generating device is a pneumatic pressure-generating device, the state detection device may include, for example, a gas pressure sensor or a device for generating the state signal based on operation of a means for supplying pressurized gas, e.g., air, to the pneumatic pressure-generating device. It should be noted that the above status signals may be generated in many ways, and embodiments of the present invention are not limited to any particular method or methods for generating the status signals.

[0028] Advantageously, the status signal 116 is an electric drive including the electric machine 100 and a converter 132 configured to drive the electric machine 100. The converter 132 is configured to receive the status signal 116 and to refrain from supplying voltage to the electric machine 100 when the actuator 105 is directing an axial force at the end of the shaft 106, to avoid unintentional start-up and possible damage to the electric machine 100 when the force-generating device 104 is operating.

[0029] Additionally, the status signal 116 can be used as a feedback signal provided to a controller configured to control the force-generating device. The feedback signal can be used, for example, to monitor that the force-generating device operates correctly in response to control actions taken by the controller. Hidden incorrect operation of the force-generating device can lead to bearing damage not only during transportation but also during other situations in which the electric machine is stopped and subjected to external vibrations and / or shocks. The feedback signal can be used to generate an alarm if the force-generating device is not operating correctly. An electric machine according to one exemplary and non-limiting embodiment includes a controller 150 configured to control the force-generating device, receive the status signal 116, and generate an alarm in response to a situation in which i) the force-generating device is controlled to direct an axial force at the end of the shaft, but ii) the status signal 116 indicates that the axial force is not being directed at the end of the shaft.

[0030] FIG. 2 illustrates a portion of an electric machine 200 according to an exemplary and non-limiting embodiment. The electric machine 200 includes a stator 201 and a rotor 202 rotatably supported relative to the stator 201 and configured to electromagnetically interact with the stator to generate torque in response to current supplied to the electric machine. In FIG. 2 , only the non-drive “ND” end of the electric machine 200 is shown. The stator 201 is shown in cross section with a geometric cross-sectional plane parallel to the yz-plane of a coordinate system 299. The stator 202 includes a stator core structure 218 and stator windings 219. The axial direction of the electric machine 200 is parallel to the z-axis of the coordinate system 299. The electric machine 200 includes a bearing configured to rotatably support the rotor 202 relative to the stator 201. In FIG. 2 , the ND-end bearing is designated by reference numeral 203. In this exemplary case, the bearing 203 is a spherical roller bearing. Correspondingly, the drive "D" end bearing of electric machine 200 may be a spherical roller bearing. The D end bearing is not shown in FIG.

[0031] The electric machine 200 includes a force generator 204 mechanically attached to the stator 201 and an actuator 205 configured to direct an axial force at the end of the shaft 206 of the rotor 202 to remove clearance from the bearings of the electric machine 200. In FIG. 2 , the end of the shaft 206 is shown in cross section with a geometric cross-sectional plane parallel to the yz-plane of the coordinate system 299. In this exemplary case, the force generator is at the ND end of the electric machine. The force generator 204 includes a hydraulic cylinder 207, and the force generator actuator 205 includes a hydraulic piston 208. In FIG. 2 , the hydraulic cylinder 207 is shown in cross section with a geometric cross-sectional plane parallel to the yz-plane of the coordinate system 299. In this exemplary case, the hydraulic cylinder 207 is a double-acting hydraulic cylinder capable of pushing the hydraulic piston 208 toward the end of the rotor shaft 206 in the negative z-direction of the coordinate system 299 and moving the hydraulic piston away from the end of the rotor shaft in the positive z-direction of the coordinate system 299.

[0032] 2, the force-generating device 204 includes pressurizers 210 and 230 that can maintain the pressure of hydraulic fluid in different compartments of the hydraulic cylinder 207 without external energy. In this exemplary case, the pressurizers 210 and 230 each include a body and a flexible bag within the body that contains hydraulic fluid.

[0033] FIG. 3 illustrates a flowchart of a method for implementing a transport support for an electric machine including a stator, a rotor rotatably supported relative to the stator and configured to electromagnetically interact with the stator to generate torque in response to current supplied to the electric machine, and bearings configured to rotatably support the rotor relative to the stator, according to one exemplary and non-limiting embodiment.

[0034] The method includes directing 301 an axial force to an end of the rotor shaft to remove clearance from the bearing using a force generating device including an actuator mechanically attached to the stator and configured to direct an axial force to the end of the rotor shaft.

[0035] In a method according to one exemplary and non-limiting embodiment, the force-generating device includes a hydraulic cylinder and the actuator of the force-generating device includes a hydraulic piston.

[0036] In a method according to one exemplary and non-limiting embodiment, the hydraulic cylinder is a double-acting hydraulic cylinder capable of pushing a hydraulic piston toward the end of the rotor shaft and moving the hydraulic piston away from the end of the rotor shaft.

[0037] In a method according to one exemplary and non-limiting embodiment, the hydraulic cylinder is a single-acting hydraulic cylinder capable of urging a hydraulic piston toward an end of the rotor shaft, and the force generating device includes a return spring configured to urge the hydraulic piston away from the end of the rotor shaft.

[0038] A method according to one exemplary, non-limiting embodiment includes maintaining hydraulic fluid pressure using a flexible material, such as air, that is compressed and tends to return to an uncompressed state.

[0039] A method according to one exemplary, non-limiting embodiment includes the use of a protective element between the actuator of the force-generating device and the end of the rotor shaft, the protective element being made of a material softer than the material of the rotor shaft, such as aluminum or nylon, and protecting the rotor shaft from shape deformation.

[0040] A method according to one exemplary and non-limiting embodiment includes: - generating a status signal indicative of whether the actuator is directing an axial force at the end of the rotor shaft; - delivering a status signal to a converter configured to drive an electric machine; - preventing the converter from supplying voltage to the electric machine when the status signal indicates that the actuator is directing an axial force at the end of the rotor shaft; Includes:

[0041] A method according to one exemplary non-limiting embodiment includes generating a status signal representative of whether an actuator is directing an axial force at an end of a rotor shaft, and issuing an alarm in response to a situation in which the status signal represents i) the force-generating device is controlled to direct an axial force at the end of the shaft, but ii) no axial force is being directed at the end of the shaft.

[0042] The specific examples provided in the above description are not to be construed as limitations on the applicability and / or interpretation of the appended claims. It should be noted that the lists and groups of examples set forth herein are not exhaustive lists and groups unless expressly stated to the contrary.

Claims

1. An electric machine (100, 200) comprising: - a stator (101, 201), a rotor (102, 202) rotatably supported relative to the stator and configured to interact electromagnetically with the stator to generate torque in response to one or more currents supplied to the electric machine; bearings (103, 203) adapted to rotatably support said rotor relative to said stator; and a force generating device (104, 204) mechanically attached to the stator and including an actuator (105, 205) configured to direct an axial force at an end of the rotor shaft (106, 206) to remove clearance from the bearing.

2. 2. The electric machine of claim 1, wherein the force generating device (104, 204) comprises a hydraulic cylinder (107, 207) and the actuator (105, 205) of the force generating device comprises a hydraulic piston (108, 208).

3. 3. The electric machine of claim 2, wherein the hydraulic cylinder (207) is a double-acting hydraulic cylinder capable of pushing the hydraulic piston (208) toward the end of the shaft of the rotor and moving the hydraulic piston away from the end of the shaft of the rotor.

4. 3. The electric machine of claim 2, wherein the hydraulic cylinder (107) is a single-acting hydraulic cylinder capable of urging the hydraulic piston (108) toward the end of the shaft of the rotor, and the force-generating device (104) includes a return spring (109) configured to urge the hydraulic piston away from the end of the shaft of the rotor.

5. 5. The electric machine of claim 2, wherein the force generating device includes a pressurizer configured to maintain hydraulic fluid pressure using a flexible material that tends to be compressed and return to an uncompressed state.

6. 6. The electric machine of claim 2, wherein the force generating device (104, 204) comprises a collar portion (112) attached to a bearing shield (113) of the electric machine and a flange portion (114) connecting to the collar portion, the hydraulic cylinder (107, 207) attached to the flange portion, and the actuator (105, 205) protruding through an aperture in the flange portion towards the end of the shaft of the rotor.

7. 7. The electric machine according to claim 1, further comprising a protective element (117) between the actuator (105) of the force generating device (104) and the end of the shaft (106) of the rotor, the protective element being made of a material softer than a material of the shaft (106) of the rotor and protecting the shaft of the rotor from shape deformation.

8. 8. The electric machine of claim 1, further comprising a state detection device configured to generate a state signal representative of whether the actuator is directing the axial force at the end of the rotor shaft.

9. 9. The electric machine of claim 8, further comprising a controller configured to control the force-generating device, receive the status signal, and issue an alarm in response to a situation in which i) the force-generating device is controlled to direct the axial force at the end of the shaft, but ii) the status signal indicates that an axial force is not being directed at the end of the shaft.

10. 1. An electric drive device, comprising: an electric machine (100), a converter (132) configured to drive said electric machine; 10. An electric drive system comprising: the electric machine (100) being an electric machine according to claim 8 or 9; and the converter configured to receive the status signal and to withhold supply of voltage to the electric machine when the status signal indicates that the actuator is directing the axial force at the end of the shaft of the rotor.

11. 1. An electric machine comprising: - a stator (101, 201), a rotor (102, 202) rotatably supported relative to the stator and configured to interact electromagnetically with the stator to generate torque in response to current supplied to the electric machine; bearings (103, 203) adapted to rotatably support said rotor relative to said stator; directing (301) an axial force to the end of the rotor shaft (106, 206) to remove clearance from the bearing using a force generating device (104, 204) mechanically attached to the stator and including an actuator (105, 205) configured to direct the axial force to the end of the rotor shaft.

12. 12. The method of claim 11, wherein the force-generating device (104, 204) comprises a hydraulic cylinder (107, 207) and the actuator (105, 205) of the force-generating device comprises a hydraulic piston.

13. 13. The method of claim 12, wherein the hydraulic cylinder (207) is a double-acting hydraulic cylinder capable of pushing the hydraulic piston (208) toward the end of the shaft of the rotor and moving the hydraulic piston away from the end of the shaft of the rotor.

14. 14. The method of claim 13, wherein the hydraulic cylinder (107) is a single-acting hydraulic cylinder capable of urging the hydraulic piston toward the end of the shaft of the rotor, and the force-generating device (104) includes a return spring (109) configured to urge the hydraulic piston away from the end of the shaft of the rotor.

15. A method according to any one of claims 12 to 14, comprising maintaining the pressure of the hydraulic fluid using a flexible material (111) that is compressed and tends to return to an uncompressed state.

16. 16. The method according to any one of claims 11 to 15, comprising the use of a protective element (117) between the actuator (205) of the force-generating device (104) and the end of the shaft (106) of the rotor, the protective element being made of a material softer than the material of the shaft (106) of the rotor and protecting the shaft of the rotor from shape deformation.

17. - generating a status signal (116) representative of whether said actuator (105) is directing said axial force at said end of said rotor shaft (106); delivering said status signal to a converter (132) configured to drive said electric machine; - preventing the converter from supplying voltage to the electric machine when the status signal indicates that the actuator is directing the axial force at the end of the shaft of the rotor; The method according to any one of claims 11 to 16, comprising:

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