DE102020007754A1 - electrical machine - Google Patents

Abstract

The invention relates to an electrical machine (1) with a housing (12), a stator (2) and a rotor (3), a rotor chamber (4) being separated from the stator ( 2) is separated, with the stator (2) being flooded with a dielectric cooling medium, with an axially running bypass channel (10) being provided at an angular position of an oil inlet (6) radially outside a stator winding or in a stator lamination, which bypass channel (10) connects the two end winding spaces ( 9) with one another, with the oil inlet (6) and an oil outlet (7) being arranged on opposite end faces of the stator (2), with another axially running bypass channel being located at the angular position of the oil outlet (7) radially outside the stator winding or in the stator lamination (10) is provided, which connects the two end winding spaces (9) to one another, with a plurality of axial channels (11) being provided distributed over the circumference, which two end winding spaces (9) ver each other bind, the axial channels (11) being integrated into the stator lamination and/or being formed in a cavity between an innermost conductor of the stator winding and the sleeve (5), the bypass channels (10) each having a larger cross-section than the axial channels (11) , wherein for the removal of small amounts of leakage of the cooling medium in the rotor space (4) a drain is provided from this.

Description

The invention relates to an electrical machine according to the preamble of claim 1.

It is known to use fully flooded electrical machines as refrigerant compressors. However, these are not suitable for use in vehicle drives, since the high speeds would result in very high friction losses on the rotor.

From the DE 198 51 439 A1 an electrical machine with a stator is known, the stator being surrounded by a housing, and a cooling arrangement connected to the housing, the stator being subjected to liquid coolant.

the EP 1 271 747 A1 discloses that cans, which enable liquid cooling of the stator, are often used in electric motors. The middle part of a split tube described is designed with thinner walls than the side parts. The shape and choice of material of these side parts are also adapted to the specific thermal conditions. The object is particularly suitable for machine tools with main spindle drives with medium-frequency synchronous motors, since the operating temperature in the bearing on the drive side can be reduced in this way. According to the method, the center part is turned and calibrated with very narrow air gaps between the stator and rotor.

The invention is based on the object of specifying an improved electrical machine.

The object is achieved according to the invention by an electrical machine with the features of claim 1.

Advantageous configurations of the invention are the subject matter of the dependent claims.

An electrical machine according to the invention comprises a housing, a stator and a rotor which can be rotated in the stator, with a rotor space in which the rotor is located being secured by a sleeve made of an electrically non-conductive and non-ferromagnetic material which is arranged in the stator and which is held at its ends against the housing is sealed, is fluid-tightly separated from the stator, wherein the stator is flooded with a dielectric cooling medium, wherein an oil inlet is arranged on an end face of the stator in a radial direction spaced from a longitudinal axis, wherein an oil outlet is arranged on an end face of the stator in a radial direction from the longitudinal axis spaced apart and offset by an angle of 180° to the oil inlet, the stator having two winding overhangs, for each of which a circumferential winding overhang space is provided for the cooling medium to flow, with an axial running B ypasskanal is provided, which connects the two end winding spaces with each other. According to the invention, the oil inlet and the oil outlet are arranged on opposite end faces of the stator, with a further axially running bypass channel being provided at the angular position of the oil outlet radially outside the stator winding or in the stator lamination, which bypass channel connects the two end winding spaces with one another, with several axial channels distributed over the circumference are provided, which connect the two end winding spaces to one another, the axial channels being integrated into the stator lamination and/or being formed in a cavity between an innermost conductor of the stator winding and the sleeve, the bypass channels each having a larger cross-section than the axial channels, the discharge being smaller Leakage quantities of the cooling medium in the rotor space, a drain is provided from this.

The solution according to the invention makes it possible to increase the (continuous) power density of the electrical machine by significantly improving the cooling.

Exemplary embodiments of the invention are explained in more detail below with reference to drawings.

• 1 eine schematische Schnittansicht einer elektrischen Maschine mit einem Stator und einem im Stator rotierbaren Rotor,
• 2 eine schematische Ansicht eines Öleinlasses, eines Ölauslasses, zweier Wickelkopfräume, von Bypasskanälen und Axialkanälen für die Kühlung des Stators der elektrischen Maschine,
• 3 schematische Diagramme eines tangentialen Volumenstroms, einer Druckdifferenz sowie eines axialen Volumenstroms in Abhängigkeit von einem Winkel für den Fall, dass keine Bypasskanäle vorgesehen wären, und
• 4 schematische Diagramme eines tangentialen Volumenstroms, einer Druckdifferenz sowie eines axialen Volumenstroms in Abhängigkeit von einem Winkel bei Verwendung von Bypasskanälen.

show:

• 1 a schematic sectional view of an electrical machine with a stator and a rotor rotatable in the stator,
• 2 a schematic view of an oil inlet, an oil outlet, two end winding spaces, bypass channels and axial channels for cooling the stator of the electrical machine,
• 3 schematic diagrams of a tangential volume flow, a pressure difference and an axial volume flow as a function of an angle in the event that no bypass channels were provided, and
• 4 schematic diagrams of a tangential volume flow, a pressure difference and an axial volume flow as a function of an angle when using bypass channels.

Corresponding parts are provided with the same reference symbols in all figures.

1 is a schematic sectional view of an electrical machine 1 with a stator 2 and a rotor 3 rotatable in the stator 2. A rotor chamber 4, in which the rotor 3 is located, is separated from the stator 2 in a fluid-tight manner by a sleeve 5 arranged in the stator 2. For example, the sleeve 5 is sealed at its ends against a housing 12 of the electrical machine 1 . The stator 2 is flooded with a dielectric cooling medium, in particular gear oil. Due to the fluid-tight, separated rotor chamber 4, this is oil-free. In order to discharge small amounts of leakage into the rotor chamber 4, a drain is provided therefrom.

The sleeve 5 is inserted into a laminated stator core and is made from an electrically non-conductive and non-ferromagnetic material in order not to generate any additional losses that would negatively affect the efficiency of the electrical machine 1 . For example, the sleeve 5 can be made of glass fiber reinforced plastic (GRP) in order to meet these requirements.

The invention enables a significant increase in the (continuous) power density of the electrical machine 1, which is based on the significantly improved cooling effect. This is caused by the cooling medium flowing over the entire end winding 8 . The winding of the electrical machine 1 consists of copper and therefore has a very high thermal conductivity. At the same time, a large part of the power loss occurs in the stator winding of the electrical machine 1 . Compared to the prior art, a water jacket cooling, a significantly improved cooling effect is achieved and thus a significant increase in the continuous power density is achieved.

Cooling via the end winding 8 is particularly effective with hairpin windings, since this offers a larger surface area for the cooling medium than a round wire winding. At the same time, however, the hairpin winding is also susceptible to tangential temperature differences between the individual conductors, since the individual conductors thermally homogenize comparatively poorly tangentially.

Therefore, a flow guide for the cooling medium is provided, which is designed to generate a sufficient flow over the entire circumference of both winding overhangs 8 and thus to achieve a uniform cooling effect over the entire winding overhang 8 . In order to achieve this, the oil supply and oil discharge are arranged on axially opposite sides and offset by an angle φ of 180°, i.e. an oil inlet 6 is arranged on an end face of the stator 2 at a distance from a longitudinal axis L in the radial direction and an oil outlet 7 is open the opposite end face of the stator 2 in the radial direction at a distance from the longitudinal axis L and offset by the angle φ of 180° to the oil inlet 6 . 2 is a schematic view of the oil inlet 6, the oil outlet 7, two winding head spaces 9, bypass channels 10 and axial channels 11. In the area of both winding heads 8, a circumferential winding head space 9 is provided in which the cooling medium can flow.

At the angular position of the oil inlet 6 and the oil outlet 7, an axially extending bypass channel 10 is provided radially outside the stator winding or in the stator lamination, which connects the two end winding spaces 9 to one another. Furthermore, several axial channels 11 are distributed over the circumference and connect the two end winding spaces 9 to one another. These axial channels 11 can be integrated into the stator lamination or can be formed via a cavity between the innermost conductor of the stator winding and the sleeve 5 . By using the cavity between the innermost conductor and the sleeve 5, it is not necessary to weaken the stator lamination; instead, a space is used that has no electromagnetic properties anyway and would otherwise only be filled with resin and/or potting compound. In one embodiment, the bypass channels 10 have a larger cross section than the axial channels 11.

3 shows a schematic diagram of a tangential volume flow V for the end windings 8 at the oil inlet 6 and at the oil outlet 7 as a function of the angle φ, a schematic diagram of a pressure difference Δ _paxial between the two end windings 8 as a function of the angle φ, and a schematic diagram of an axial volume flow V̇ _axially between the two end windings 8 as a function of the angle φ in the event that no bypass channels 10 were provided. 4 shows a schematic diagram of a tangential volume flow V for the end windings 8 at the oil inlet 6 and at the oil outlet 7 as a function of the angle φ, a schematic diagram of a pressure difference Δ _paxial between the two end windings 8 as a function of the angle φ, and a schematic diagram of an axial volume flow V̇ _axially between the two end windings 8 depending on the angle φ when using bypass channels 10.

The bypass channels 10 ensure that the volume flow V is sufficiently large in all areas of the end winding 8 . Without the bypass channels 10 at 0° and 180°, a tangentially flowing volume flow V in the end winding area would approach zero in precisely these areas. Furthermore, the bypass channels 10 ensure a more uniform volume flow V - _axially via the remaining axial channels 11 and thus to a tangentially more even cooling.

The supply and discharge axially opposite, offset by 180° with bypass channels 10 at 0° and 180°, means that the pressure gradients remain the same over the circumference and, moreover, enables both a uniform flow through the axial channels 11 and a sufficient flow through the end winding space 9 in the circumferential direction will.

The electrical machine 1 can be used, for example, to drive an electrically powered vehicle.

Reference List

1

electric machine

2

stator

3

rotor

4

rotor space

5

sleeve

6

oil inlet

7

oil outlet

8th

winding head

9

end winding space

10

bypass channel

11

axial channel

12

Housing

L

longitudinal axis

V

tangential flow

V̇axial

axial volume flow

Δpaxial

pressure difference

φ

angle

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was 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.

Patent Literature Cited

• DE 19851439 A1 [0003]
• EP 1271747 A1 [0004]

Claims (3)

Electrical machine (1) with a housing (12), a stator (2) and in the stator (2) rotatable rotor (3), wherein a rotor space (4) in which the rotor (3) is located by an im Stator (2) arranged sleeve (5) made of an electrically non-conductive and non-ferromagnetic material, which is sealed at its ends against the housing (12), is fluid-tightly separated from the stator (2), the stator (2) having a dielectric cooling medium is flooded, an oil inlet (6) being arranged on an end face of the stator (2) in the radial direction spaced from a longitudinal axis (L), an oil outlet (7) being arranged on an end face of the stator (2) in the radial direction from the longitudinal axis ( L) spaced and offset by an angle (φ) of 180° to the oil inlet (6), the stator (2) having two end windings (8), for each of which a circumferential end winding space (9) is provided for the cooling medium to flow , Wherein on the angular position of the oil inlet (6) radially outside An axially running bypass channel (10) is provided in a stator winding or in a stator lamination, which connects the two end winding spaces (9) to one another, characterized in that the oil inlet (6) and the oil outlet (7) are on opposite end faces of the stator (2nd ) are arranged, with a further axially running bypass channel (10) being provided at the angular position of the oil outlet (7) radially outside the stator winding or in the stator lamination, which connects the two end winding spaces (9) to one another, with several axial channels (11 ) are provided which connect the two end winding spaces (9) to one another, the axial channels (11) being integrated into the stator sheet metal and/or being formed in a cavity between an innermost conductor of the stator winding and the sleeve (5), the bypass channels (10) each have a larger cross section than the axial channels (11), with the removal of small amounts of leakage of the cooling medium in de n rotor space (4) a drain is provided from this. Electrical machine (1) according to claim 1 , characterized in that the sleeve (5) is made of glass fiber reinforced plastic. Electrical machine (1) according to one of Claims 1 or 2 , characterized in that the stator winding is designed as a hairpin winding.

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