DE102014014770A1 - Electric motor with a stator and rotor - Google Patents

Abstract

Electric motor with a stator and rotor,
wherein the stator is arranged in a housing,
the housing accommodating bearings which support the rotor,
wherein the housing accommodates two spaced-apart magneto-fluid seals, each of which seals the rotor against the housing part,
wherein the motor interior disposed between the magneto-fluid seals is at least partially filled with a medium,
the medium being liquid below a boiling temperature and gaseous above the boiling point,
wherein a first surface portion of the boundary of the motor interior has a lower temperature than the boiling temperature of the medium present at the pressure occurring during operation,
wherein a second surface portion of the boundary of the motor interior has a higher temperature than the boiling temperature of the medium present at the pressure occurring during operation

Description

The invention relates to an electric motor with a stator and rotor.

From the internet page http://www.vacom.de/produkte/mechanischedurchfuehrungen/drehdurchfuehrungen-mit-magnetofluid-dichtung as of 26.9.2014 at 2:10 pm magneto-fluid seals are known. Unlike conventional rotary joints with elastomeric or bellows seals, a magnetofluid rotary union uses a magnetizable fluid (magnetic fluid) as a dynamic seal that fills the gap between the rotating shaft and the static housing. Strong magnetic solenoids form the magnetic fluid in the form of liquid O-rings, creating a low-friction seal between the shaft and the housing.

The invention is therefore based on the object to perform an electric motor as compact as possible with the highest possible power per volume.

According to the invention, the object is achieved in the electric motor according to the features indicated in claim 1.

Important features of the invention in the electric motor with a stator and rotor according to claim 1,
that the stator is arranged in a housing,
the housing accommodating bearings which support the rotor,
wherein the housing accommodates two spaced-apart magneto-fluid seals, each of which seals the rotor against the housing part,
wherein the motor interior disposed between the magneto-fluid seals is at least partially filled with a medium,
the medium being liquid below a boiling temperature and gaseous above the boiling point,
wherein, in particular during operation, in particular in the case of a permanently executed rated operation of the engine, a first surface section of the boundary of the motor interior has a lower temperature than the boiling temperature of the medium present at the pressure occurring during operation,
wherein, in particular during operation, in particular in the case of a permanently performed nominal operation of the engine, a second surface section of the boundary of the motor interior has a higher temperature than the boiling temperature of the medium present at the pressure occurring during operation,
in particular, wherein the boiling temperature deviates at least 10 Kelvin from the lowest and the highest temperature.

The advantage here is that the most homogeneous temperature distribution in the engine interior is reached. Because the thermal hotspots, such as stator winding or active part of the rotor, have in operation at a temperature which exceeds the boiling point of the medium located in the engine compartment. Thus, the medium becomes gaseous in the region of the thermal hotspots and absorbs heat energy through this phase transition as well as through the further heating and transports it to the flange part, ie to that boundary section of the motor interior which has a temperature below the boiling temperature. By condensation on the flange, the heat is released to this flange and discharged from this to the environment or to a flange flowing through the cooling medium. The condensed medium is liquid and flows along the surface of the flange part which at least partially surrounds the motor interior, to the gap region between rotor and stator. Thus, the medium is supplied to the hotspots and is thus able to absorb heat again. The medium is therefore a working medium. In addition to the medium, air may also be in the engine compartment. The air, however, transports heat only in a convective way.

Important features of the invention in the electric motor with a stator and rotor according to claim 2,
that the stator is arranged in a housing,
the housing accommodating bearings which support the rotor,
wherein the housing accommodates two spaced-apart magneto-fluid seals, each of which seals the rotor against the housing part,
wherein the motor interior disposed between the magneto-fluid seals is at least partially filled with a medium,
the medium being liquid below a boiling temperature and gaseous above the boiling point,
wherein a first surface portion of the boundary of the motor interior has a lowest temperature along the boundary during operation, in particular in the case of permanently executed nominal operation of the engine, and a second surface section of the boundary of the motor interior has a highest temperature along the boundary,
wherein the boiling temperature of the medium at the pressure occurring during operation is between the lowest and the highest temperature,
in particular, wherein the boiling temperature deviates at least 10 Kelvin from the lowest and the highest temperature.

The advantage here is that the most homogeneous temperature distribution in the engine compartment is reachable. Because the thermal hotspots, such as stator winding or active part of the rotor, have in operation at a temperature which exceeds the boiling point of the medium located in the engine compartment. Thus, the medium becomes gaseous in the region of the thermal hotspots and absorbs heat energy through this phase transition as well as through the further heating and transports it to the flange part, ie to that boundary section of the motor interior which has a temperature below the boiling temperature. By condensation on the flange, the heat is released to this flange and discharged from this to the environment or to a flange flowing through the cooling medium. The condensed medium is liquid and flows along the surface of the flange part which at least partially surrounds the motor interior, to the gap region between rotor and stator. Thus, the medium is supplied to the hotspots and is thus able to absorb heat again. The medium is therefore a working medium. In addition to the medium, air may also be in the engine compartment. The air, however, transports heat only in a convective way.

In an advantageous embodiment, the housing has a housing part, which receives the stator, in particular a stator lamination stack of the stator,
wherein the housing part is connected to a first flange part of the housing and a second flange part of the housing, wherein the two flange parts are spaced from each other,
wherein the flange parts each receive one of the bearings. The advantage here is that a compact design is possible.

In an advantageous embodiment, a stator winding of the stator is received by the laminated stator core and is encapsulated with potting compound. The advantage here is that the engine interior is bordered by potting compound and thus a chemically inert choice of material to the medium is possible.

In an advantageous embodiment, the rotor has a mounted on the bearing in the housing rotor shaft and a rotatably connected to the rotor shaft active part. The advantage here is that the active part can reach high temperatures and thus can be effective as a hotspot, so that the medium when contacting the area of the hotspot is gaseous.

In an advantageous embodiment, in each case a shaft sealing ring is arranged on the side remote from the respective magneto-fluid seal side of the respective bearing, which is accommodated in the housing, in particular in a respective flange of the housing, and runs on the rotor shaft. The advantage here is that a higher level of security can be achieved. Because even with failure of the magneto-fluid seal another seal is effective. In addition, the bearing is oil lubricated operable that the lubricating oil between magneto-fluid seal and shaft seal is limited.

In an advantageous embodiment of the motor interior is limited to the outside by the flange and the potting compound of the stator winding and the magneto-fluid seals,
in particular wherein the motor interior is also bounded by the rotor shaft and by the active part of the rotor. The advantage here is that only a few materials are to be selected, which are chemically inert to the medium, so do not react chemically with the medium.

In an advantageous embodiment, during operation, the flange parts have a lower temperature than the active part and / or the potting compound of the stator winding,
in particular, wherein the lowest temperature of the engine compartment occurs at a surface portion of one of the flange parts. The advantage here is that the flange are suitable for condensation of the medium and thus dissipate the heat to the outside.

In an advantageous embodiment, the flange parts each have at least one channel, which is flowed through by a cooling medium, such as oil or water. The advantage here is that a further improved heat dissipation is effected.

In an advantageous embodiment, the motor interior is in each case at least partially bounded by a depression of the respective flange part, the diameter of which grows monotonously, in particular strictly monotonically, with increasing axial distance from the respective magneto-fluid seal.
in particular wherein the largest diameter of the recess is a diameter of the gap between the stator and the rotor or the smallest inner diameter of the stator. The advantage here is that the condensed medium to the gap region is feasible and thus is available as soon as possible for a vaporization in the range of a hotspot available. In this way, a fast circulation of the medium in the engine compartment and thus a quick removal of the heat can be carried out.

In an advantageous embodiment, the respective flange part has a recess facing the motor interior in particular, the diameter of which increases monotonously, in particular strictly monotonically, with increasing axial distance from the respective magneto-fluid seal,
in particular, wherein the largest diameter of the recess corresponds to a diameter of the gap between the stator and rotor or the smallest inner diameter of the stator. The advantage here is that the condensed medium to the gap region is feasible and thus is available as soon as possible for a vaporization in the range of a hotspot available. In this way, a fast circulation of the medium in the engine compartment and thus a quick removal of the heat can be carried out.

In an advantageous embodiment, the engine compartment on an overpressure or negative pressure relative to the ambient air. The advantage here is that the boiling temperature can be controlled with the specified pressure. Thus, the most effective possible Entwärmmen the engine is achievable.

Further advantages emerge from the subclaims. The invention is not limited to the combination of features of the claims. For the skilled person, further meaningful combination options of claims and / or individual claim features and / or features of the description and / or figures, in particular from the task and / or the task posing by comparison with the prior art arise.

The invention will now be explained in more detail with reference to figures:

In the 1 an inventive electric motor is shown.

This motor has a housing part 1 on the front axial side and on the rear axial side, each with a flange 4 tight, in particular pressure-tight, is connected.

The housing part 1 surrounds a stator of the electric motor, which is a laminated stator core 2 and a stator winding received therein 3 having. Preferably, the stator with the housing part non-positively and / or cohesively, in particular by means of potting compound, connected.

In the respective flange part 4 is each a warehouse 6 a rotor shaft 8th added.

With the rotor shaft 8th is an active part rotatably connected, which is the rotor shaft 8th radially surrounding in an axial section. This active part has a rotor core 10 and a rotor winding received therein 11 on. Preferably, the rotor winding 11 executable as a short-circuit cage. This is, for example, by casting with the rotor laminated core 10 connectable. The motor is thus an asynchronous motor.

On the output side, ie on the axially remote from the engine compartment side of the output-side bearing 6 , A shaft seal is arranged in the output side flange part 4 is recorded and on the rotor shaft 8th running. For this purpose, the output-side flange part 4 a bearing seat.

The output side end of the rotor shaft 8th is connected to a driven, rotatably mounted part of a machine, wherein the housing, in particular the output-side flange part 4 , the motor is connected to the housing of the machine.

Between the respective flange part 4 and the rotor shaft 8th are also two more seals 5 arranged as a magneto-fluid seal 5 are executed. The respective magneto-fluid seal 5 is between each camp 6 and the engine compartment arranged. The magneto-fluid seal 5 allows a gas-tightness at high negative pressure or overpressure in the engine compartment relative to the environment of the engine.

In the engine compartment, a medium is filled, which is liquid at low temperatures and at an operating temperature, in particular at a temperature of a hotspot during operation, the engine is gaseous. In this way, a thermal homogenization is achieved, so that rotor, stator and acting as end shields flange parts 4 have the same temperature. Because after commissioning, the medium is first gaseous where a higher temperature occurs than in the rest of the engine. Thus, such thermal hotspots are effectively cooled, since the gaseous medium removes the heat and has a high thermal conductivity, in particular a much higher thermal conductivity compared to air. An essential effect is also the phase transition of the medium. Because during the phase transition from the liquid state to the gaseous state, additional heat is absorbed.

Advantageously, therefore, an isothermal temperature distribution in the engine interior is achieved in this way.

The gaseous medium also permeates the air space in the gap between rotor and stator in a quick and simple manner. This gap is designed substantially hollow cylindrical and is flowed through by the gaseous medium.

Preferably, the stator winding 3 executed with potting compound. In this case, a positive connection with the motor interior facing side of the flange 4 advantageous, with additional seals, such as O-rings, are providable. Thus, the winding heads protrude the stator winding 3 each in an annular recess of the respective flange 4 in and between with Potting compound potted and encapsulated winding heads and the respective flange 4 An O-ring is arranged.

In this way, therefore, the engine compartment is pressure-tight, in particular gas-tight, sealed against the environment. Thus, the medium is not lost. The medium selected is not air but preferably a hydrocarbon compound comprising substance or water or a water-containing mixture.

The flange bearing part acting as end shield 4 has a through hole through which the medium is refillable. This hole is pressure-tight with a closure element, in particular gas-tight, sealed.

The space region in which the medium is located is thus limited by the magneto-fluid seals, the flange parts, the potting compound with which the stator winding is encapsulated, and by the laminated stator core or by a coating of the laminated stator core. In addition, this space is limited inwards by the rotor and its active part. Because these rotatably mounted parts go through the space area. Thus, the Raumberiech also includes the gap between the rotor and stator.

If, during operation, a surface section, for example, of the active part of the rotor or a surface section of the stator has a higher temperature than the boiling temperature of the medium, the medium located on this surface section changes to the gaseous state. After the arrival of this gaseous medium at a surface portion of the space region, which has a lower temperature than the boiling temperature, the medium then goes back to the liquid state. For example, the respective flange is correspondingly cool. The driven-side flange part 4 is formed in such a way that the condensed, ie liquid medium is passed into the gap between the rotor and stator. For this purpose, the flange part 4 a depression seen from the axial direction, the diameter of which increases monotonically in the axial direction. Likewise, the other flange part 4 a recess seen from the axial direction, the diameter of which increases monotonically opposite to the axial direction.

The largest diameter corresponds to the diameter of the gap between rotor and stator. Thus, this flows on the flange part 4 condensed medium along the bottom of the depression along in the gap. The flange part 4 has a low temperature, since the outer surface of the flange 4 adjacent to the ambient air. In the gap, however, there is a high temperature because of the high operating currents. Thus, located at the boundary of the gap hotspots, where the liquid medium passes into the gaseous state.

For example, the flange part 4 in continuous operation, in particular at nominal load, on its outer surface at a temperature of 90 ° C and the stator winding or the active part of the rotor has a temperature of 135 ° C. Since the boiling point of the medium should be between these temperatures, water can be used as the medium, for example. The space region of the medium preferably has an overpressure with respect to the outside environment. Thus, the boiling temperature is for example 110 ° C.

For other embodiments, other temperatures are provided. The boiling temperature of the medium is controllable in a simple manner by the pressure difference between the medium area comprising the medium and the external environment. Depending on the temperature and chemical composition of the boundary of the room area, another medium can be selected instead of water. It is important that the medium is chemically inert within the operating time with the materials surrounding the spatial area, such as potting compound, metallic material of the flange, materials of the active part, materials of the magneto-fluid seal.

In a further embodiment of the invention, the rotor on its surface facing the stator on such structures that the gaseous medium is conveyed in the axial direction through the gap between the stator and the rotor. For return promotion against the axial direction, the stator or the housing part 1 axially extending recesses, which open axially on both sides in the engine compartment. If the recesses are arranged in the stator, it is advantageous, these recesses in the laminated stator core 2 to arrange. By casting compound corresponding connection channels are guided so that a cycle of the flowing gaseous medium can be reached.

In a further embodiment of the invention, the active part is equipped with permanent magnets, so that the motor is a synchronous motor. Alternatively, the active part as an active part of a reluctance motor executable. Thus, the active part then has radially protruding metal regions and can be operated as a reluctance motor.

In a further embodiment of the invention is by means of a pressure control device, such as pump or other actuator, in particular compression device, the pressure in Engine interior controlled. With a pressure sensor arranged in the interior of the engine, it is even possible to regulate the pressure to a target value.

The pressure to be controlled, in particular desired value for pressure, is predetermined such that the boiling temperature of the medium is controlled accordingly. In this way, at low operating temperature, so low utilization of the engine, a low boiling temperature value reached and high operating temperature, ie high utilization, a high value of the boiling temperature. This boiling temperature control allows for effective defrosting at different engine utilization levels and / or different ambient temperatures.

In a further embodiment of the invention, a different Dcihtung, such as shaft seal or combi shaft seal is used instead of the magneto-fluid seal. However, then a more frequent refilling of the medium in the engine compartment is necessary.

LIST OF REFERENCE NUMBERS

1

housing part

2

stator lamination

3

stator

4

flange

5

Magneto-fluid seal

6

camp

7

Shaft seal

8th

rotor shaft

9

Interior area of the engine

10

Laminated core

11

rotor winding

12

Sealing, like O-ring

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• http://www.vacom.de/produkte/mechanischedurchfuehrungen/drehdurchfuehrungen-mit-magnetofluid- Dichtung [0002]

Claims (12)

Electric motor with a stator and rotor, wherein the stator is arranged in a housing, wherein the housing accommodates bearings which support the rotor, characterized in that the housing receives two spaced-apart seals, in particular magneto-fluid seals, each receiving the rotor against Seal the housing part, the arranged between the seals, in particular magneto-fluid seals, motor interior is at least partially filled with a medium, the medium is liquid below a boiling temperature and above the boiling point gaseous, wherein, in particular during operation, especially at permanently executed nominal operation of the engine, a first surface portion of the boundary of the engine compartment has a lower temperature than the pressure at the occurring during operation pressure of the medium, wherein, in particular during operation, in particular at permanently running m rated operation of the engine, a second surface portion of the boundary of the engine compartment has a higher temperature than that occurring at the pressure occurring during operation pressure of the medium, in particular wherein the boiling temperature deviates at least 10 Kelvin from the lowest and the highest temperature. Electric motor with a stator and rotor, wherein the stator is arranged in a housing, wherein the housing accommodates bearings which support the rotor, characterized in that the housing receives two spaced-apart seals, in particular magneto-fluid seals, each receiving the rotor against Seal the housing part, wherein the arranged between the seals, in particular magneto-fluid seals, motor interior is at least partially filled with a medium, the medium below a boiling temperature liquid and above the boiling point is gaseous, wherein during operation, especially in permanently running rated operation of the engine, a first surface portion of the boundary of the engine compartment has a lowest temperature along the boundary and a second surface portion of the boundary of the engine compartment has a highest temperature along the boundary, the auftre during operation the boiling point of the medium lying between the lowest and highest temperature, in particular wherein the boiling temperature deviates at least 10 Kelvin from the lowest and the highest temperature. Electric motor according to at least one of the preceding claims, characterized in that the housing has a housing part, which accommodates the stator, in particular a stator lamination stack of the stator, wherein the housing part is connected to a first flange part of the housing and a second flange part of the housing, wherein the two flange portions are spaced from each other, wherein the flange receive each one of the bearing. Electric motor according to at least one of the preceding claims, characterized in that a stator winding of the stator is received by the stator lamination and is encapsulated with potting compound. Electric motor according to at least one of the preceding claims, characterized in that the rotor has a mounted on the bearing in the housing rotor shaft and a rotatably connected to the rotor shaft active part. Electric motor according to at least one of the preceding claims, characterized in that on the side remote from the respective magneto-fluid seal side of each bearing a shaft seal is arranged, which is housed in the housing, in particular in a respective flange of the housing, and running on the rotor shaft , Electric motor according to at least one of the preceding claims, characterized in that the motor interior is limited to the outside by the flange and the potting compound of the stator winding and the seals, in particular magneto-fluid seals, in particular wherein the motor interior and the rotor shaft of the active part of the rotor is bounded. Electric motor according to at least one of the preceding claims, characterized in that during operation, the flange parts have a lower temperature than the active part and / or the potting compound of the stator winding, in particular, wherein the lowest temperature of the engine compartment occurs at a surface portion of one of the flange parts. Electric motor according to at least one of the preceding claims, characterized in that the flange parts each have at least one channel which is flowed through by a cooling medium, such as oil or water. Electric motor according to at least one of the preceding claims, characterized in that the motor interior is at least partially bounded by a recess of the respective flange, the diameter monotonically, in particular strictly monotonously increases with increasing axial distance from the respective magneto-fluid seal, in particular wherein the largest Diameter of the recess corresponds to a diameter of the gap between the stator and rotor or the smallest inner diameter of the stator. Electric motor according to at least one of the preceding claims, characterized in that the respective flange has an in particular the engine compartment facing recess whose diameter increases monotonically with increasing axial distance from the respective magneto-fluid seal, in particular strictly monotonous, in particular wherein the largest diameter of the recess a diameter of the gap between the stator and the rotor or the smallest inner diameter of the stator. Electric motor according to at least one of the preceding claims, characterized in that the motor interior has an overpressure or negative pressure relative to the ambient air.

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