DE102015014689A1 - Rotor with a measuring element for temperature determination of the rotor - Google Patents

Abstract

The invention relates to a rotor (10) for an electric machine. In this case, the rotor (10) comprises a laminated core (14), at least one short-circuit ring (20) which is arranged on an end face (16) of the laminated core (14), at least one short-circuiting bar (18) which extends from the at least one short-circuit ring (16). 20) extends in the axial direction through the laminated core (14), and a measuring element (22) which is adapted to detect a temperature at a predetermined measuring point on the rotor (10). Furthermore, the rotor has a laying channel in which the measuring element (22) is arranged.

Description

The invention relates to a rotor for an electric machine according to the preamble of patent claim 1.

During operation of the electrical machine, heat losses can occur within the electrical machine. Especially the rotor of the electric machine is thermally heavily loaded during operation of the electric machine. Heat losses are caused, for example, by high rotor speeds, by the current flowing through the conductor in the rotor or by the air friction. These heat losses must be dissipated to prevent overheating or damage to the electrical machine or the rotor.

The heat losses during operation of the electric machine or the rotor can cause thermal expansion. The rotor for an electric machine may be, for example, a squirrel cage rotor. Such thermal expansions are manifested, for example, by elastic or plastic widening of the casting compound of the rotor on short-circuiting rods and / or short-circuiting rings.

In order to reduce the high thermal load in the rotor, in particular on the potting compound of the rotor, the electric machine is cooled. The heat losses during operation of the electric machine can be dissipated, for example by means of a fluid cooling. In a fluid cooling, a cooling fluid, for example an oil, is fed in between the stator and the rotor.

For controlling the fluid cooling or for determining the volume flow of the cooling fluid, the temperature at the most thermally stressed points within the electrical machine, in particular the temperature of the rotor to determine.

Object of the present invention is therefore to provide a rotor of the type mentioned, which allows a simpler and more reliable temperature determination of the rotor.

This object is achieved by a rotor with the features of claim 1. Advantageous embodiments with expedient developments of the invention are specified in the remaining claims.

In order to provide a rotor of the type specified in the preamble of patent claim 1, in which a temperature determination can be carried out particularly simply and reliably, it is inventively provided that the rotor has a laying channel in which the measuring element is arranged. Preferably, the measuring element is guided through the laying channel to a predetermined measuring point in the rotor. The laying channel is preferably arranged within a short-circuit ring. Alternatively, the routing channel may be located within the shorting ring and within a shorting bar. In other words, the laying channel may preferably be integrated in a potting compound of the short-circuit ring and / or the short-circuiting rod of the rotor. Under a laying channel, for example, a tubular passage or a blind hole to understand. Alternatively, the laying channel can also be designed as a groove and / or depression and extend along a surface of the rotor, in particular along a surface of the shorting ring and / or the shorting bar, in the axial direction or radial direction. The groove and / or recess may be formed, for example groove-shaped.

The invention is based on the finding that measuring elements, which are arranged to determine the temperature of the rotor on a surface of the rotor, are mechanically heavily loaded during operation of the electric machine and can even be torn off. The mechanical loading of the measuring elements is achieved in particular by the thermal expansion of the rotor and / or by the flow of the cooling fluid. As a result of the arrangement of the measuring element in the laying channel, the measuring element is not exposed to any direct mechanical loads, for example the flow of the cooling fluid. By laying in the laying channel further no filler material, such as an adhesive is necessary to attach the measuring element to the rotor.

The measuring element is preferably a thermocouple. A thermocouple is a pair of metallic conductors of different materials connected at one end. Due to the occurring thermoelectric effect, a temperature can be determined. This results in the advantage that the temperature of the rotor can be determined in a particularly cost-effective and therefore economical manner.

An embodiment of the invention provides that the laying channel comprises a first channel section, the first channel section extending radially inside the at least one shorting ring from an inner diameter of the at least one shorting ring in the direction of the outer diameter of the at least one shorting ring. In other words, the first channel section within the at least one shorting ring can be arranged from an inner side of the at least one shorting ring, which corresponds to a shaft of the Rotor facing radially towards an upper side of the at least one short-circuit ring extend. By top of the shorting ring is meant the surface which extends in a uniform radial distance parallel to the inside of the at least one shorting ring. By radial is meant here the direction which extends perpendicular to the main extension direction of the rotor, that is the axis of rotation of the rotor.

Preferably, the first channel portion is formed as a blind hole having a predetermined depth, starting from the inner diameter of the at least one short-circuit ring. The first channel portion may extend in the radial direction within the potting compound of the rotor, for example, up to half of the short-circuit ring. The first channel section preferably has only one opening. This results in the advantage that the measuring element integrated in a particularly simple manner in the potting compound of the rotor and the core temperature can be determined in the short-circuit ring particularly reliable.

Advantageously, the laying channel may have a second channel portion which is coupled to the first channel portion and extends in the axial direction from the first channel portion into a shorting bar of the rotor. In other words, the second channel section runs perpendicular to the first channel section from the at least one short-circuiting ring into a short-circuiting bar of the rotor. The second channel portion of the routing channel preferably extends for a predetermined length into the shorting bar. Preferably, the laying channel with the first channel portion and the second channel portion in cross-section parallel to the axis of rotation of the rotor has an L-shape. By "coupled" is meant here that the first channel section and the second channel section of the routing channel merge directly into each other. By axial direction is meant here the direction which extends parallel to the main extension direction of the rotor, that is to say the axis of rotation of the rotor. This has the advantage that the core temperature in the short-circuiting rod can be determined in a particularly simple manner.

Additionally or alternatively, an annular balancing element is preferably arranged on an end face of the at least one short-circuit ring. Motors of electrical machines, such as electric motors, are balanced to reduce or eliminate imbalance during operation of the electric machine. For balancing rotors two different methods can be used. A first method is a negative balancing method. Therein, bores or notches are provided in the laminated core and / or the short-circuit ring of the rotor, thereby reducing the weight of the rotor. A second balancing method is a positive balancing method. In this process, additional material is attached to the rotor. For example, additional potting compound is attached to the potting compound of the shorting ring. The balancing element is preferably arranged in overlapping with the short-circuit ring concentric with the shaft of the rotor. The balancing element may, for example, have an extension of 2.5 millimeters to 10 millimeters, in particular 5 millimeters, in the axial direction. Preferably, the short-circuit ring and the balancing element are formed from a potting compound.

Advantageously, the laying channel comprises a third channel portion, the third channel portion extending radially inwardly of the annular balancing member from an inner diameter of the annular balancing member in the outer diameter direction of the annular balancing member, and wherein the laying channel comprises a fourth channel portion connected to the third channel portion is coupled and extends in the axial direction of the third channel portion in the annular balancing element in the at least one short-circuit ring or in the axial direction through the at least one short-circuit ring in a shorting bar of the rotor. The balancing element is thus not only designed to reduce an imbalance of the rotor during operation of the electrical machine, but can additionally accommodate the measuring element by the third channel section and / or fourth channel section.

In a further embodiment, the first channel section or the third channel section is preferably formed meander-shaped or rectilinear. By "meandering" is meant a serpentine course of the first and / or third channel section.

The at least one short-circuit ring or the annular balancing element advantageously has a deflection opening, wherein the first channel section or third channel section of the routing channel is coupled to the deflection opening, wherein a deflection element can be inserted into the first channel section or third channel section via the deflection opening, wherein the deflection element is designed to deflect the measuring element axially from the first channel section or third channel section into the second channel section or fourth channel section when arranging the measuring element in the second channel section or fourth channel section. Due to the deflection opening, there is the advantage that the measuring element is particularly simply in the second channel section and fourth channel section can be laid.

In an advantageous manner, in a mounted state of the measuring element in the deflection opening, a closure element for hermetically sealing the laying channel with respect to an environment of the rotor is arranged. For example, the deflection opening is sealed with an adhesive, in particular a structural adhesive or a two-component adhesive. This results in the advantage that the deflection opening can be closed in a particularly simple and cost-effective manner.

Further advantages, features and details of the invention will become apparent from the following description of a preferred embodiment and from the drawings. The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively specified combination but also in other combinations or in isolation, without the scope of To leave invention.

Showing:

1 a schematic perspective view of a rotor of an electrical machine with threaded measuring elements;

2 an enlarged view of the rotor 1 ;

3 an enlarged view of the rotor 1 ;

4 partial view of a side view of the rotor 1 ; and

5 a perspective view of a short-circuit ring of the rotor with threaded measuring elements.

In the figures, the same or functionally identical elements are provided with the same reference numerals.

In 1 is a rotor in a perspective view 10 shown for an electric machine. At the rotor 10 it is preferably a squirrel cage. The electric machine can be designed for example as a motor or as a generator. The electric machine is preferably part of a motor vehicle, in particular a passenger car.

Out 1 it can be seen that the rotor 10 rotatable with a while 12 connected is. The wave 12 is preferably formed as a hollow shaft. The wave 12 is rotatable about an axis of rotation and in the rotor 10 stored. Furthermore, the rotor comprises 10 a laminated core 14 , In the laminated core 14 runs from one end face 16 of the laminated core 14 to one of the front side 16 axially opposite end face of the laminated core 14 a shorting bar 18 , In the laminated core 14 are in the circumferential direction at uniform and predetermined intervals to each other a plurality of shorting bars 18 arranged. The shorting bar 18 is on the front side 16 of the laminated core 14 with one at the front 16 of the laminated core 14 arranged shorting ring 20 connected. At the front 16 axially opposite end face of the laminated core 14 is another shorting ring (in 1 not shown). The other short-circuit ring is, as well as the short-circuit ring 20 , with the shorting bar 18 connected or electrically coupled. Furthermore, the rotor includes 10 a measuring element 22 , The measuring element 22 first passes through a channel 24 , which is schematically indicated by the arrow, in the axial direction in the direction of the short-circuit ring 20 , Below an inner diameter 28 of the short-circuit ring 20 becomes the measuring element 22 radially into a first channel section 26 - indicated by the radial arrow - deflected. The first channel section 26 extends radially from an inner diameter 28 of the short-circuit ring 20 within the shorting ring 20 in the direction of an outer diameter 30 of the short-circuit ring 20 , Out 1 it can be seen that the first channel section 26 the short-circuit ring 20 not completely radially from the inner diameter 28 up to an outer diameter 30 penetrates, but up to a predetermined point inside the short-circuit ring 20 runs.

To the first channel section 26 borders a second channel section 32 at. In other words, the first channel section 26 with the second channel section 32 coupled. The first channel section 26 goes into the second channel section 32 above. The second channel section 32 extends from the first channel section 26 axially in the direction of the shorting bar 18 , About the second channel section 32 can the measuring element 22 in the short-circuit bar 18 be guided. In the circumferential direction of the rotor 10 can at predetermined angular distances from each other a plurality of first channel sections 26 and second channel sections 32 , each with a first channel section 26 are coupled, be arranged. For example, in the circumferential direction at 90 ° intervals to each other four first channel sections 26 be arranged. Between the four first channel sections 26 can be another four first channel sections 26 , each with a second channel section 32 are coupled, in the circumferential direction at an angular distance of 45 ° to each one of the first four channel sections 26 be arranged. Again, four second channel sections 32 at 90 ° intervals in the circumferential direction of the rotor 10 symmetrical to the axis of rotation of the rotor 10 be arranged.

As 2 can be seen, it may also be provided that on the short-circuit ring 20 an annular balancing element 34 is arranged. The short-circuit ring 20 and the balancing element 34 are preferably formed from a potting compound. The short-circuit ring is preferred 20 , the balancing element 34 and the shorting bar 18 formed from a potting compound. The potting compound may comprise, for example, aluminum. In other words, the short-circuit ring 20 and / or the balancing element 34 and / or the shorting bar 18 together form a unity. As already in connection with the first channel section 26 described, which is within the shorting ring 20 extends, may be a third channel section 36 from an inner diameter of the annular balancing member 34 in the direction of an outer diameter of the annular balancing element 34 extend.

To the third channel section 36 includes a fourth channel section 38 or a fifth channel section 42 at. As already in connection with the first channel section 26 and the second channel section 32 described is the fourth channel section 38 or the fifth channel section 42 with the third channel section 36 coupled. The coupling of the third channel section 36 and the fourth channel section 38 For example, go out 2 out. The third channel section 36 and the fourth channel section 38 are indicated by the arrows. Therein, the fourth channel section extends 38 starting from the third channel section 36 which extends radially inside the balancing element 34 extends, axially in the direction of the front side 16 of the laminated core 14 up to a given measuring point within the short-circuit ring 20 ,

Not just the core temperature of the shorting ring 20 be determined, but also the core temperature of the shorting bar 18 so leads, as in 3 shown the fifth channel section 42 over a predetermined length into the shorting bar 18 , The fifth channel section 42 is with the third channel section 36 coupled.

In 4 is a partial side view of the rotor 10 the extension of the fourth channel section 38 from the balancing element 34 in the short-circuit ring 20 indicated by the short arrow. The fifth channel section 42 extending from the balancing element 34 over the short-circuit ring 20 in the short-circuit bar 18 extends is indicated by the long arrow. in the circumferential direction of the rotor 10 can alternately at predetermined angular intervals to each other several fourth channel sections 38 and fifth channel sections 42 , each with a third channel section 36 are coupled, be arranged. For example, four fourth channel sections each 38 be arranged in the circumferential direction at 90 ° intervals to each other. Between the fourth channel sections 38 can each have a fifth channel section 42 in the circumferential direction at an angular distance of 45 ° to the fourth channel section 38 be arranged. Again, four fifth channel sections 42 at 90 ° intervals in the circumferential direction of the rotor 10 be arranged symmetrically. Overall, the rotor can 10 So for example, eight third channel sections 36 , four fourth channel sections 38 and four fifth channel sections 42 exhibit. The third channel sections are preferred 36 , fourth channel sections 38 and fifth channel sections 42 in the circumferential direction of the rotor 10 symmetrical to the axis of rotation of the rotor 10 arranged.

To the measuring element from the radially extending first channel section 26 or third channel section 36 axially in the second channel section 32 and / or fourth channel section 38 or fifth channel section 42 to redirect, the shorting bar points 18 or the balancing element 34 a deflection opening 40 on. About the deflection opening 40 is a deflecting element in the first channel section 26 or third channel section 36 insertable, wherein the deflecting element is adapted to, when arranging the measuring element 22 in the second channel section 32 or fourth 38 or fifth channel section 42 the measuring element 22 from the first one 26 or third channel section 36 in the second 32 or fourth 38 or fifth channel section 42 to deflect axially. In the assembled state of the measuring element 22 becomes the deflection opening 40 then with an adhesive hermetically against an environment of the rotor 10 sealed.

At this point, in the following, even closer to the production of the channel 24 and / or the first channel section 26 and / or second channel section 32 and / or third channel section 36 and / or fourth channel section 38 and / or fifth channel section 42 the laying channel of the rotor 10 To be received.

To the measuring element in the channel 24 the wave 12 order to be able, by means of a erosion process, the channel 24 generated. Also in an erosion process are the first channel section 26 and / or the second channel section 32 and / or the third channel section 36 and / or the fourth channel section 38 and / or fifth channel section 42 the laying channel of the rotor 10 generated. In the following, the steps of the erosion process using the example of the third channel section 36 and the fifth channel section 42 be explained in more detail. For the third channel section 36 first becomes the balancing element 34 processed. This is the balancing element 34 provided with a channel or a bore with a diameter of for example 2 millimeters. For the fifth channel section 42 will be the balancing element next 34 and the short-circuit ring 20 axially eroded with a diameter of 2 millimeters to the measuring point of the measuring element. This will be the third channel section 36 with the fifth channel section 42 connected.

Thereafter, the eroded hole - third channel section and fifth channel section is eroded again, but with a larger compared to the first diameter diameter of, for example, 4 millimeters. The measuring element 22 will now be in the third channel section 36 threaded and led out at the deflection, for example by means of an eyelet. Following by means of a deflecting element, for. B. a loop, the measuring element 22 axially in the fifth channel section 42 deflected and to the end fifth channel section 42 introduced. The fifth channel section 42 extends, for example, starting from the front side 16 of the laminated core 14 up to half of the shorting bar 18 , Subsequently, the deflection opening 40 closed with an adhesive. Likewise, alternative methods, such as drilling and / or milling, can be used instead of an eroding method.

In 5 is the short-circuit ring with two first channel sections 26 and each arranged therein measuring elements 22 shown. The first channel section 26 can, how out 5 emerges, for example, be designed as a groove-shaped groove. The first channel section 26 But also, as already related to the 1 to 4 described as a tubular channel in the potting compound of the shorting ring 20 or the balancing element 34 be integrated. As 5 can be seen, the first channel section 26 have a rectilinear shape and / or a meandering shape.

Overall, therefore, a method for temperature determination of the Rotorvergusses by Vergussintegrierte measuring points in wet-running electric motors emerges.

The high rotor speeds (nominal speed: 16,000 rpm up to the permissible overspeed of up to 22,400 rpm) lead to elastic-plastic widening of the aluminum casting on short-circuit bars and rings. Above all in areas that are subject to voids due to air and vibration porosities. The material movements lead to material fatigue and temperature increases in the casting. In addition to the mechanical stress caused by the high speeds, high electrical currents flow through the short-circuit bars, which also leads to material heating. Furthermore, the rotor heats up by a further 30 ° C to 40 ° C due to air friction at maximum speed. In order to reduce the high thermal loads on the aluminum casting, the rotor is designed with oil cooling, which means that oil is fed in between the stator and the rotor. To control the oil cooling and the current flow, however, the Vergusstemperatur must be determined in order to avoid overheating of the rotor. The following procedure allows for the application of conventional thermocouples in the rotor casting. As a result, the temperature measurement in the core of the encapsulation is only possible because on the one hand tear off the thermocouples on the surface due to the oil flow and on the other not meaningful enough to characterize or control the flow of oil to cool the electric machine.

By laying the thermocouples in the encapsulation of the short-circuit ring, the thermocouples are neither burdened nor torn by the oil or air turbulence and are not subject to any mechanical wear. In addition to the safe separation, this also enables the detection of the core temperature in the short-circuit ring and in the short-circuit bars of the aluminum casting. Furthermore, no additive can be released by the occurring loads (inter alia shear loads due to fluid) and cause further damage.

First, an additional lead of 5 millimeters must be cast on the rotor in the encapsulation of the short-circuit ring. This widens the short-circuit ring by 5 millimeters. Subsequently, this is first processed radially via an erosion process. This gives the short-circuit ring a channel with a diameter of 2 millimeters (diameter thermo-cable 1 millimeter). Next, the short-circuit ring is axially eroded with a diameter of 2 millimeters to the measuring point of the thermocouple. Thereafter, the eroded bore is eroded again, but with a diameter of 4 millimeters and to a depth of 5 millimeters (until the thermocouple passes through). The thermocouple is now threaded from below into the short-circuit ring and led out at the axial bore by means of eyelet. Then, by means of grinding, the thermocouple is inserted axially to the end of the erosion. Subsequently, the bore opening is closed with adhesive (two-component structural adhesive or liquid metal adhesive). The asymmetric routing of the thermocouples leads on the one hand by the material removal and the thermocouples to change the imbalance. This can be avoided by a symmetrical arrangement of the thermocouples. Furthermore, the cavity can be closed again by aluminum, in order to prevent unbalance and line resistance unaffected. This process can be scaled up or down to different diameters of the thermocouples. Likewise, alternative methods such as drilling, milling et cetera can be used instead of an erosion process.

LIST OF REFERENCE NUMBERS

10

rotor

12

wave

14

laminated core

16

front

18

Shorting bar

20

Shorting ring

22

measuring element

24

channel

26

first channel section

28

inner diameter

30

outer diameter

32

second channel section

34

Wuchtungselement

36

third channel section

38

fourth channel section

40

deflection opening

42

fifth channel section

Claims (8)

Rotor ( 10 ) for an electrical machine comprising: - a laminated core ( 14 ), - at least one short-circuit ring ( 20 ), which at one end face ( 16 ) of the laminated core ( 14 ), - at least one short-circuit bar ( 18 ), which differs from the at least one short-circuit ring ( 20 ) in the axial direction through the laminated core ( 14 ), and - a measuring element ( 22 ), which is adapted to a temperature at a predetermined measuring point on the rotor ( 10 ), characterized in that the rotor ( 10 ) has a laying channel in which the measuring element ( 22 ) is arranged. Rotor ( 10 ) according to claim 1, characterized in that the laying channel has a first channel section ( 26 ), wherein the first channel section ( 26 ) radially within the at least one short-circuit ring ( 20 ) of an inner diameter ( 28 ) of the at least one short-circuit ring ( 20 ) in the direction of the outer diameter ( 30 ) of the at least one short-circuit ring ( 20 ). Rotor ( 10 ) according to claim 2, characterized in that the laying channel has a second channel section ( 32 ) which is connected to the first channel section ( 26 ) and in the axial direction of the first channel section ( 26 ) into a short-circuit bar ( 18 ) of the rotor ( 10 ). Rotor ( 10 ) according to claim 1, characterized in that at one end face of the at least one short-circuit ring ( 20 ) an annular balancing element ( 34 ), wherein the laying channel has a third channel section ( 36 ), wherein the third channel section ( 36 ) radially within the balancing element ( 34 ) of an inner diameter of the balancing element ( 34 ) in the direction of the outer diameter of the balancing element ( 34 ) and wherein the laying channel has a fourth channel section ( 38 ) which is connected to the third channel section ( 36 ) and in the axial direction of the third channel section ( 36 ) in the balancing element ( 34 ) in the at least one short-circuit ring ( 20 ) or in the axial direction through the at least one Kurschlußring ( 20 ) into a short-circuit bar ( 18 ) of the rotor ( 10 ). Rotor ( 10 ) according to one of claims 2 to 4, characterized in that the first ( 26 ) or the third channel section ( 36 ) is meander-shaped or rectilinear Rotor ( 10 ) according to one of claims 3 to 5, characterized in that the at least one short-circuit ring ( 20 ) or the balancing element ( 34 ) a deflection opening ( 40 ), the first ( 26 ) or third channel section ( 36 ) of the laying channel with the deflection opening ( 40 ), wherein via the deflection opening ( 40 ) a deflecting element in the first ( 26 ) or third channel section ( 36 ) is insertable, wherein the deflecting element is adapted to, when arranging the measuring element ( 22 ) in the second ( 32 ) or fourth channel section ( 38 ) the measuring element from the first ( 26 ) or third channel section ( 36 ) in the second ( 32 ) or fourth channel section ( 38 ) axially deflect. Rotor ( 10 ) according to claim 6, characterized in that in the mounted state of the measuring element ( 22 ) in the deflection opening ( 40 ) a closure element for hermetically sealing the laying channel with respect to an environment of the rotor ( 10 ) is arranged. Rotor ( 10 ) according to one of the preceding claims, characterized in that the measuring element ( 22 ) is designed as a thermocouple.

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