Insulation of coil windings of active parts of electric machines

Abstract

The invention relates to a method for insulating a coil winding (3) of an active component (5) of a rotating electrical machine. In this method, the active component (5) is first impregnated with an insulating resin (30) in a trough-shaped impregnation container (7) by vacuum pressure impregnation. The impregnation container (7) filled with the insulating resin (30) is then introduced into a baking oven together with the active component (5) arranged therein, and the active component (5) in the insulating resin (30) is set in rotation about the longitudinal axis (15) of the active component (5). During the rotation of the active component (5), the insulating resin (30) is discharged from the impregnation container (7), and then the oven temperature is increased to a preset baking temperature and maintained at the baking temperature for a preset baking duration. After the baking duration has expired, the rotation of the active component (5) is terminated.

Description

Technical Field

[0001] The invention relates to a method for insulating coil windings of an active component of a rotating electrical machine, ie a stator or a rotor, and to a device for carrying out the method. Background Art

[0002] More specifically, the invention relates to the insulation of coil windings of active components of rotating electrical machines, wherein the coil windings are impregnated with insulating resin by so-called vacuum pressure impregnation (VPI). During vacuum pressure impregnation, the active components are first degassed in a vacuum and then immersed in insulating resin. Finally, the insulating resin and the active components immersed in the insulating resin are subjected to an overpressure in order to press the insulating resin into the evacuated cavities of the active components which have not been filled with insulating resin up to this point. In this context, it is necessary to prevent a relatively large amount of insulating resin from flowing out of the active components again after impregnation. The resin outflow has the disadvantage of producing poorer insulation values ​​on the one hand, but also has the more serious disadvantage of producing insulation which can be easily damaged or destroyed in the event of a sudden decompression. Such damage can be caused by shrinkage cavities in the insulation, i.e. by closed cavities which are formed by the outflowing resin and into which gases at high process gas pressures to which the machine is subjected diffuse during operation of the electrical machine into the cavities, which then fill the cavities with such high process gas pressures. In the event of a rapid drop in pressure in the motor environment, the gas expanding into the shrinkage cavity cannot escape quickly enough, so that an overpressure forms in the shrinkage cavity due to the gas remaining there, which leads to rupture or delamination of the insulation.

[0003] In the case of certain resins, the outflow of the insulating resin can be reduced after impregnation by so-called accelerators, wherein an accelerator is a material which is introduced into the coil winding to be impregnated and which gels the insulating resin during the impregnation process and thus prevents outflow. However, such accelerators cannot be used in all insulating resins, in particular in certain resins which are necessary for the insulation of the windings of certain fast-running electric machines and which must withstand high voltages when cooled by process gas. Summary of the invention

[0004] The invention is based on the object of specifying an improved method for insulating coil windings of an active component of a rotating electrical machine by means of vacuum pressure impregnation and a device for carrying out the method.

[0005] According to the invention, this object is achieved by a method having the features of the invention and by a device having the features of the invention.

[0006] Advantageous embodiments of the invention are the subject matter of the individual exemplary embodiments.

[0007] In the method according to the invention for insulating the coil windings of an active component of a rotating electrical machine, the active component is first impregnated with insulating resin by vacuum pressure impregnation in a trough-shaped impregnation container. The impregnation container, which is still filled with insulating resin, is then introduced into a baking oven together with the active component arranged therein, and the active component in the insulating resin is set into rotation about the longitudinal axis of the active component. During the rotation of the active component, the insulating resin is discharged from the impregnation container, and the oven temperature is then increased to a preset baking temperature and maintained at the baking temperature for a preset baking duration. The rotation of the active component is not terminated until the baking duration has expired.

[0008] In the method according to the invention, the outflow of insulating resin from the active component is significantly reduced after vacuum pressure impregnation by placing the active component in rotation and keeping it in rotation during the curing of the insulating resin. It is particularly advantageous here that the active component is already placed in rotation while it is still immersed in the insulating resin and that the rotation is maintained during the discharge of the insulating resin from the impregnation container and during the baking in the baking oven. This prevents in particular the passage of time between the discharge of the insulating resin and the start of baking, during which time the active component is not rotating and during which time more insulating resin can flow out accordingly, because, for example, the active component is only transported to the baking oven after the insulating resin has been discharged, is then positioned in the baking oven and finally has to be connected to a rotary drive.

[0009] In one embodiment of the method according to the invention, the active component in the impregnation container is set in rotation by a chain drive. In particular, it can be provided that the active component is held in the impregnation container by two chains and is set in rotation via at least one of the two chains, wherein the active component is suspended at the active component carrier via the two chains. This embodiment of the method according to the invention takes into account that according to the invention, the active component is still immersed in the insulating resin at the beginning of the rotation. The chain drive is adapted to this aspect of the invention because it simply transmits the drive torque to the active component via the chain, and the chain can also be replaced cheaply in the event of contamination by the insulating resin. In addition, this embodiment of the method according to the invention simultaneously makes it possible to appropriately suspend the active component at the active component carrier via the chain in order to hold the active component in the impregnation container during the vacuum pressure impregnation and the subsequent rotation of the active component.

[0010] In another embodiment of the method according to the present invention, the baking furnace is preheated to a preheating temperature lower than the baking temperature before the impregnation container filled with the insulating resin and the active components arranged in the impregnation container are introduced. Thus, the baking furnace can be preheated to a temperature at which the insulating resin has a viscosity suitable for discharging the insulating resin.

[0011] In another embodiment of the method according to the invention, after the baking duration has expired, the furnace temperature is reduced to the final temperature according to a predefined temperature reduction curve. In this case, it can be provided that the rotation of the active component is terminated after the furnace temperature has reached the final temperature. This embodiment of the method according to the invention allows uniform and controlled cooling of the active component and the insulating resin at the coil winding, so that stresses in the insulating resin caused by temperature differences, which could damage the insulation, can be avoided.

[0012] The device according to the invention for carrying out the method according to the invention comprises an impregnation container, which is designed to accommodate the active component and is filled with insulating resin until the active component is completely immersed in the insulating resin, at least one first sprocket that can be connected to the active component, and an active component carrier, which is designed to hold the active component in the impregnation container and has a second sprocket for each first sprocket, which can be connected to the first sprocket via a chain, wherein at least one second sprocket can be driven by a drive in order to set the active component into rotation about its longitudinal axis. The device according to the invention enables the method according to the invention to be carried out with the advantages already mentioned above.

[0013] In one embodiment of the device according to the invention, each first sprocket can be releasably connected to the active component via at least one connecting element. As a result, the first sprocket can be advantageously used multiple times to insulate the coil windings of the active component.

[0014] According to another embodiment of the device according to the invention, two first sprockets are provided, which can be connected to the active component at the sides of the active component that are opposite along the longitudinal axis of the active component, and the active component can be suspended on the active component carrier via the first sprockets by means of corresponding chains in order to hold the active component in the impregnation container. In this case, it can be provided that the spacing between the two second sprockets can be adjusted. This makes it possible to suspend the active component on the active component carrier via two chains in the manner already proposed above. In addition, the adjustability of the spacing of the two second sprockets advantageously makes it possible to match the spacing of the second sprockets to the spacing of the first sprockets or to the axial extension of the active component, and thus use the device according to the invention for active components with different axial extensions.

[0015] In another embodiment of the device according to the invention, the impregnation container has a container bottom with a drain pipe which opens into a container opening which can be closed by a closure device. This advantageously simplifies the outflow of insulating resin from the impregnation container.

[0016] According to another embodiment of the device of the invention, a carrier insert is provided, which has walls arranged in a grid-like manner and can be arranged on the active component carrier in such a way that when the active components in the impregnation container are immersed in the insulating resin, the walls extend into the insulating resin above the active components. As a result, shaking of the insulating resin in the impregnation container (in particular during the transport of the impregnation container filled with the insulating resin into the baking oven) can be advantageously reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The following description of the embodiments in conjunction with the accompanying drawings will more clearly explain the above-described characteristics, features and advantages of the present invention and the ways and methods of achieving them. It is shown here:

[0018] Figure 1 A perspective view of an embodiment of a device according to the invention for insulating a coil winding of an active component with an active component arranged thereon or therein,

[0019] Figure 2 Show Figure 1 A perspective view of the active component and the first sprocket connected to the active component,

[0020] Figure 3 A flow chart of an exemplary embodiment of a method according to the invention for insulating a coil winding of an active component is shown.

[0021] Parts that correspond to one another are provided with the same reference symbols in the figures. DETAILED DESCRIPTION

[0022] Figure 1 A perspective view of an embodiment of a device 1 according to the invention for insulating a coil winding 3 of an active component 5 of a rotating electrical machine is shown. The device 1 comprises an impregnation container 7, an active component carrier 9 and two first sprockets 11,12.

[0023] Figure 2 Show Figure 1 FIG. 4 is a perspective view of an active component 5 and first sprockets 11 , 12 connected to the active component 5 .

[0024] The active component 5 has a laminated core 13 which extends in a ring around a longitudinal axis 15 of the active component 5. The longitudinal axis 15 defines an axial direction. The laminated core 13 has axially extending slots 17 through which straight sections of the coil winding 3 extend, which are connected to form a coil at both axial ends of the laminated core 13 by corresponding winding heads of the coil winding 3. The slots 17 are closed by slot closing wedges (not shown).

[0025] The first sprockets 11, 12 are arranged on axially opposite sides of the active component 5 and extend respectively about the longitudinal axis 15. Each first sprocket 11, 12 is fixedly arranged on a carrier disk 19, 20, which is connected to the laminated core 13 via a connecting element 21 designed as a connecting rod. The carrier disks 19, 20 are detachably connected to the connecting element 21 via a screw connection 23.

[0026] The impregnation container 7 is trough-shaped and has a container bottom with a drain pipe 25. The drain pipe 25 opens at the lowest point of the impregnation container 7 into a container opening 29 which can be closed by a closure device 27. The impregnation container 7 is filled with an insulating resin 30 so that the active component 5 is completely immersed in the insulating resin 30.

[0027] The active component carrier 9 comprises a carrier frame 33 arranged on a carrier leg 31. Two carrier beams 35, 36 are arranged on the carrier frame 33, at which second sprockets 37, 38 are respectively arranged. Each second sprocket 37, 38 is connected to the first sprocket 11, 12 via a chain 39, 40. The carrier beams 35, 36 can be fixed at different positions on the carrier frame 33, so that the spacing of the second sprockets 37, 38 can be matched to the spacing of the first sprockets 11, 12 or the axial extension of the active component 5.

[0028] A carrier insert 41 is inserted into the active component carrier 9, and the carrier insert has walls 43 arranged in a grid. The walls 43 extend into the insulating resin 30 on the upper part of the active component 5.

[0029] The active component 5 is suspended on the active component carrier 9 by means of chains 39, 40. The at least one second sprocket 37, 38 can be driven by a drive (not shown) in order to set the active component 5 into rotation about the longitudinal axis 15.

[0030] Figure 3 The method for utilizing the Figure 1 The illustrated flow chart 100 shows an exemplary embodiment of a method for insulating a coil winding 3 of an active component 5 using a device 1 , the method having method steps 101 to 107 .

[0031] In a first method step 101, the active components 5 in the impregnation container 7 are impregnated with the insulating resin 30 by vacuum pressure impregnation. For this purpose, the carrier plates 19, 20 are fixed to the active components 5 by means of connecting elements 21. The active component carrier 9 is lifted over the active components 5, for example by means of a crane, until each first sprocket 11, 12 can be hooked into a chain 39, 40 hanging from the second sprocket 37, 38. After the first sprockets 11, 12 have been hooked, the active component carrier 9 with the active components 5 hanging thereon is lifted and lowered over the impregnation container 7, so that the active components 5 are held by the active component carrier 9 in the impregnation container 7. The impregnation container 7 and the active component carrier 9 are then connected to one another, for example by means of a screw connection. The impregnation container 7 and the active component carrier 9 with the active components 5 hanging thereon are then moved into a pressure container. The pressure container is closed and evacuated, and the active components are degassed in the evacuated pressure container for a preset degassing duration. At the same time, the insulating resin 30 is heated to a preheating temperature, for example, to about 70° C. Then, the heated insulating resin 30 in the evacuated pressure vessel is pumped into the impregnation vessel 7 through the vessel opening 29 until the filling level of the insulating resin 30 in the impregnation vessel 7 reaches a preset value, at which the active component 5 is completely immersed in the insulating resin 30. Then, the active component 5 is impregnated with the insulating resin 30 during the impregnation duration. Then, the pressure in the pressure vessel is increased to the overpressure during the overpressure duration, and then reduced to the normal pressure again.

[0032] In a second method step 102, firstly, the carrier insert 41 is inserted into the carrier frame 33. Subsequently, the impregnation container 7 still filled with insulating resin 30 and the active component carrier 9 with the active component 5 suspended thereon are introduced into a baking oven preheated to a preheating temperature.

[0033] In a third method step 103 , the active component 5 in the insulating resin 30 is set into rotation about the longitudinal axis 15 , for example at an angular speed of approximately three revolutions per minute, by driving at least one second sprocket 37 , 38 by a drive, for example via a cardan shaft.

[0034] In a fourth method step 104, the insulating resin 30 is pumped out of the impregnation container 7, while the active component 5 continues to rotate. Optionally, after the insulating resin 30 has been pumped out, a large-area collecting trough is pushed under the open container opening 29 in order to collect trailing insulating resin 30, for example dripping from the active component 5, and distribute it over a large area in order to avoid spontaneous combustion of the insulating resin 30 during baking in a fifth method step 105.

[0035] In a fifth method step 105 , the oven temperature is increased to a preset baking temperature, for example approximately 170° C., and maintained at the baking temperature during a preset baking duration, for example approximately eight hours.

[0036] In a sixth method step 106 , the furnace temperature is gradually reduced to a final temperature according to a predefined temperature reduction curve.

[0037] In a seventh method step 107, after the furnace temperature has reached the final temperature, the rotation of the active component 5 is terminated. The cooled device 1 is then disassembled and all parts of the device 1 that are in contact with the insulating resin 30 (impregnation container 7, sprockets 11, 12, 37, 38, chains 39, 40, carrier discs 19, 20 and carrier insert 41) are checked and, if necessary, cleaned or replaced.

[0038] Although the present invention has been illustrated and described in detail by means of preferred embodiments, the present invention is not limited to the disclosed examples and a person skilled in the art can derive other variants therefrom without departing from the scope of protection of the present invention.

Claims

1. A method for insulating a coil winding (3) of an active component (5) of a rotating electrical machine, wherein - the active component (5) is impregnated with the insulating resin (30) by vacuum pressure impregnation in a tank-shaped impregnation container (7), and after the active component (5) is impregnated with the insulating resin (30), the active component is held in the insulating resin (30) in a manner completely immersed in the impregnation container (7) filled with the insulating resin (30), - Subsequently, the impregnation container (7) filled with the insulating resin (30) is introduced into a baking oven together with the active component (5) arranged in the impregnation container, and the active component (5) in the insulating resin (30) is placed in rotation about the longitudinal axis (15) of the active component (5), - during the rotation of the active component (5), the insulating resin (30) is discharged from the impregnation container (7), and then the furnace temperature is increased to a preset baking temperature and maintained at the baking temperature for a preset baking duration, - and after expiration of the baking duration, ending the rotation of the active component (5).

2. The method according to claim 1, wherein: The active component (5) in the impregnation container (7) is set in rotation by a chain drive.

3. The method according to claim 2, wherein: The active component (5) is held in the immersion container (7) by means of two chains (39, 40) and is set into rotation by means of at least one of the two chains (39, 40), wherein the active component (5) is suspended on an active component carrier (9) by means of the two chains.

4. The method according to any one of claims 1 to 3, wherein: Before introducing the impregnation container (7) filled with the insulating resin (30) and the active component (5) arranged in the impregnation container (7), the baking furnace is preheated to a preheating temperature lower than the baking temperature.

5. The method according to any one of claims 1 to 3, wherein: After the baking duration has expired, the furnace temperature is reduced to a final temperature according to a preset temperature reduction curve.

6. The method according to claim 5, wherein: After the furnace temperature reaches the final temperature, the rotation of the active component (5) is terminated.

7. A device (1) for performing the method according to any one of claims 1 to 6, the device (1) comprising - an impregnation container (7) which is provided for receiving the active component (5) and which is filled with an insulating resin (30) until the active component (5) is completely immersed in the insulating resin (30), - at least one first sprocket (11, 12) connectable to the active component (5), and - an active component carrier (9) which is provided for holding the active component (5) in the impregnation container (7) and which has, for each first sprocket (11, 12), a second sprocket (37, 38) which can be connected to the first sprocket (11, 12) via a chain (39, 40), wherein: At least one second sprocket (37, 38) can be driven by a drive in order to set the active component (5) into rotation about a longitudinal axis (15) of the active component.

8. The device (1) according to claim 7, wherein Each first sprocket (11, 12) can be releasably connected to the active component (5) via at least one connecting element (21).

9. The device (1) according to claim 7 or 8, comprising two first sprockets (11, 12) which can be connected to the active component (5) at opposite sides of the active component (5) along the longitudinal axis (15) of the active component (5) and can suspend the active component (5) on the active component carrier (9) by means of corresponding chains (39, 40) via the first sprockets in order to hold the active component (5) in the impregnation container (7).

10. The device (1) according to claim 9, wherein: The distance between the two second sprockets (37, 38) can be adjusted.

11. The device (1) according to claim 7 or 8, wherein: The impregnation container (7) has a container bottom with a water discharge line (25) which opens into a container opening (29) which can be closed by a closure device (27).

12. The device (1) according to claim 7 or 8, having a carrier insert (41) having walls (43) arranged in a grid-like manner and being arrangeable at the active component carrier (9) in such a way that when the active component (5) in the impregnation container (7) is immersed in the insulating resin (30), the walls (43) extend into the insulating resin (30) above the active component (5).

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