EP1425841A1

EP1425841A1 - Method for cooling a transverse flow synchronous machine and transverse flow synchronous machine

Info

Publication number: EP1425841A1
Application number: EP02779337A
Authority: EP
Inventors: Andreas Lange; Wolfram Angerer; Uwe Mühlberger
Original assignee: Voith Turbo GmbH and Co KG
Current assignee: Voith Turbo GmbH and Co KG
Priority date: 2001-09-14
Filing date: 2002-09-11
Publication date: 2004-06-09
Also published as: DE10145447A1; US20060082248A1; US7129602B2; WO2003026102A1

Abstract

The invention concerns a method for cooling a transverse flow synchronous machine comprising a rotor and a stator forming at least respectively an outer intermediate gap in the radial direction. The outer stator, which is associated with the rotor so as to be spaced apart therefrom by a ventilating interstice in the radial direction, comprises in the circumferential direction a plurality of substantially efficient individual elements spaced apart from one another by specific distances and associated with the rotor in corresponding and complementary manner. According to said method, at least a partial zone of the stator is cooled, and the inside of the synchronous machine is partly filled at least with a cooling medium. The invention is characterized in that when the synchornous machine is not operating and is being mounted, a layer of cooling medium is formed whereof the surface is at least at the zone of the outer intermediate gap located beneath the axis of symmetry of the synchronous machine, between the rotor and the stator, and when the synchronous machine is operating, the rotation of the rotor drives the cooling medium, which is then sprayed in the intermediate gaps between the individual elements of the stator.

Description

Method for cooling a synchronous machine with transverse flow guidance and synchronous machine with transverse flow guidance

The invention relates to a method for cooling a synchronous machine with transverse flow guidance, in particular a transverse flow machine; also a synchronous machine with transverse flow guidance.

Synchronous machines with transverse flow guidance are described, for example, in the following documents (1) DE 35 36 538 A1

(2) DE 3705089 C1

(3) DE 3904516 C1

(4) DE 4125779 C1. These essentially describe the basic principle and the structure.

These include at least one stator with at least one armature winding and a rotor opposite the armature winding. The rotor consists of at least two ring elements arranged next to one another, separated by an intermediate layer of magnetically and electrically non-conductive material, which have a plurality of alternately arranged polarized magnets and soft iron elements in the circumferential direction. Such an arrangement of two ring elements forms a pole structure. Transverse flux machines are preferably constructed symmetrically. These then comprise two pole structures separated by a central carrier disk.

With such a machine, heat is generated in operation both in the rotor and in the stator due to the power losses which occur due to the windings and the magnetic cores and are caused by induced eddy currents. If suitable measures are not taken, this limits the resilience and thus also the availability or operating time of the AC machine. The situations in which such a machine works under high load and above all at high speed are particularly critical. In order to avoid this disadvantageous effect, it is generally known to connect the stator to cooling devices. In this way, heating of the machine and its components can be reduced.

DE 43 35 848 A1 discloses a large number of possibilities for improving the cooling effect, in particular to design a cooling arrangement in such a way that it has at least one cooling channel which is installed in the region or in the vicinity of the carrier disk in the stator and through which a cooling fluid flows becomes. Each cooling channel is only one of the carrier disc

Channel cover of minimal thickness and the air gap between the rotor and stator separated. Also known from this publication is an embodiment with an at least axially extending cooling channel in a spacer which is provided between a pair of stator sections. The spacer is radially opposite the carrier disc, is arranged symmetrically to the carrier disc and is thermally insulated from the stator sections. This consists of a material that is magnetically passive and has good thermal conductivity.

Another known way to reduce heat is to use the

To provide the carrier disk and the areas of the stator located opposite each other in the area of the cooling channels with interlocking complementary teeth which have surfaces which run essentially parallel to one another and are separated from one another by an air gap.

It is also known to provide additional measures on the rotor either instead of the measures described above for stator cooling and thus indirectly for rotor cooling. This has at least one pair of collector rings, which are connected by an insulating ring made of magnetically passive and electrically non-conductive material, memory cells being incorporated in the circumferential direction and filled with a phase change material. The effect of these known measures can be increased by a suitable choice of material and surface treatment.

The disadvantage of the known designs is that large cooling effects can only be achieved with a high manufacturing expenditure. The most stressed and heated areas of the rotor can often not be optimally and above all not evenly cooled. Due to the structure of the transverse flux machine, cooling of some areas of the rotor is only possible indirectly, in particular the connection points between the individual ring elements of a pole structure and / or the connection between the carrier disk and the pole structures. However, these are the areas most exposed to warming.

From document WO 98/25331 a method for cooling an alternating current machine with a rotor and a stator is known, which each form at least one radially inner and / or radially outer space with one another, in particular of synchronous machines with transverse flow guidance, in which the ones that cannot be directly cooled are known Areas of the rotor are cooled by means of a coolant-air mixture that is created due to atomization. For this, the AC machine, especially the

The transverse flux machine is partially filled such that, at least in the installed position below the rotor axis, a coolant sump is formed in a non-operating manner in such a way that when the AC machine is operated, the coolant is partially entrained and atomized by the rotor rotation and the atomized particles in at least one of the spaces and thus in can reach the area of the rotor. The filling takes place in such a way that a coolant sump is formed below the rotor axis in the radially outer space, also referred to as an air gap, in the installed position between the rotor and the stator. The operation of the alternating current machine essentially occurs depending on the speed of the rotor shaft and the

Level a coolant-air mixture in the air gap between rotor and stator. This takes over through heat flow and heat transfer Heat transfer from the rotor to the water-cooled stator, for example. The coolant-air mixture essentially only takes on the heat transport, which is why no additional devices for cooling the coolant have to be provided and a one-time partial filling with coolant which remains inside the AC machine is generally sufficient. However, it has now been shown that in the case of the transverse flux machines corresponding to the design described in the documents 1 to 4, this method does not achieve the desired effects, that is to say the rotor does not nevertheless experience the desired cooling.

The invention is therefore based on the object of carrying out a cooling arrangement for a synchronous machine with transverse flow guidance in such a way that, in addition to ensuring effective cooling of the synchronous machine with transverse flow guidance, in particular the rotor as a particularly heavily stressed component, a low constructional and cost-effective expenditure is recorded is.

The solution according to the invention is characterized by the features of claims 1 and 7. Advantageous configurations are described in the subclaims.

The solution according to the invention for optimal rotor cooling for synchronous machines with transverse flow guidance is characterized by the use of a cooling method in which, due to the rotor rotation, a coolant located in the coolant sump is atomized into a coolant-air mixture for a special stator construction and a rotor design. The stator construction is characterized in that only the inner stator carries an armature winding, while the outer stator is made up of a large number of individual stator elements, which are designed as solid profile components, preferably made of powder-metallurgically manufactured and pressed materials. These are essentially designed as strip-shaped individual elements that face the rotor Form or carry tooth elements that can be attached directly to the stator housing with simple fastening elements - detachable or non-detachable. The large number of individual stator elements on the outer stator, which are arranged at a certain distance from one another in the circumferential direction and which therefore always form an intermediate space, enables a considerable increase in surface area and thus a substantial increase in the contact points for the coolant / air mixture to accommodate the by means of this heat dissipated by the rotor. In contrast, the individual stator units, in particular the, exist in conventional designs of synchronous machines with transverse flux guidance

External stator made up of a plurality of soft iron units arranged one behind the other, which are embedded in the stator housing and thus illustrate an essentially smooth stator structure. The rotor structure is characterized by a non-smooth outer surface. The rotor has a stepped structure which is produced by changing radial dimensions of the magnet arrangements and soft iron elements arranged alternately in the circumferential direction. This rotor structure significantly favors the atomization of the coolant. According to the invention, the synchronous machine with transverse flow guidance is partially filled with a coolant in such a way that in the installed position in the mathematical sense below the rotor axis, in particular in the

The area of the outer air gap between the rotor and the outer stator forms a coolant sump when not in operation, which is entrained, swirled and atomized on the individual stator elements and the atomized particles first because of the staged structure of the rotor immersed in the coolant sump when not in operation and then because of the negative pressure that arises during rotor rotation reach the area of the rotor from the gaps. The rotor therefore only plunges directly into the coolant sump when it is not in operation and after commissioning for a short period of time. The coolant is entrained due to the pressure conditions caused by the structure of the rotor. The rotor is therefore not cooled directly by the coolant, but by the swirl and

Nebulization of the coolant-air mixture. The coolant is atomized into many individual droplets, under normal pressure and normal Temperature conditions in the synchronous machine. The droplet mist is distributed over the entire interior of the machine. The rotor is cooled by heat transfer to the stator elements. No additional sealing is required. This process is carried out free of hydraulic friction. Due to the gaps caused by the stator construction, the

The available stator area, in particular on the outer stator, is considerably enlarged, which on the one hand has a positive effect on the atomization and on the other hand also considerably increases the surface area available for heat dissipation with regard to the possible cooling. Since the coolant-air mixture essentially only takes on the heat transport, it is not necessary to provide additional devices for cooling the coolant. A single partial filling with coolant, which remains inside the AC machine, is sufficient.

The spaces between the rotor and the stator are defined with respect to their radial position based on the theoretical symmetry or the axis which corresponds to the axis of rotation of the rotor.

Preferably, the low viscosity coolant, i.e. used with a low internal friction due to force effects between the molecules, for example in the form of low-viscosity oil.

The solution according to the invention offers the possibility of dissipating heat even at the critical areas of the rotor, which could previously only be insufficiently cooled by means of conventional cooling arrangements.

The heat can be removed from the stator by means of conventional simple stator cooling devices, for example cooling channels in the stator housing.

The solution according to the invention can also be used as an additional measure

Cooling can be used in combination with conventional cooling measures. For machines with low output, however, partial filling in combination with simple stator cooling is sufficient.

The selection of the suitable combinations of the oil mist cooling according to the invention with conventional cooling arrangements for stator cooling lies in

The specialist's discretion and depends on the specific application. The stator can be cooled in different ways, directly or indirectly using different cooling media. In the simplest case, this is connected to corresponding cooling devices or coolant channels which can be filled with coolant are provided in the stator main body.

In addition, there is also the possibility of combining the cooling of the rotor according to the invention with already known measures for indirect cooling of the rotor, in particular for local cooling of rotor sections.

Here are some examples:

For example, it is conceivable to provide in the stator in the vicinity of the carrier disk at least one cooling channel through which a cooling fluid can flow, the cooling channel from the carrier disk only through a channel cover of minimal thickness and the space between

Rotor and stator is separated.

In a special embodiment, the cooling channel can extend axially and be installed in a spacer which is arranged between a pair of stator sections. The spacer is arranged symmetrically in the radial direction opposite the carrier disk and thermally insulated from the stator sections. The spacer is preferably made of a material that is magnetically passive and has good thermal conductivity. On both sides of the cooling channel, it has essentially radially extending, large-area cavities which provide thermal insulation from the neighboring ones Form areas of the stator. The cavities can be filled with air or other insulation materials.

Furthermore, the cooling channel can be arranged in the base body of the stator.

With regard to further possible measures, reference is made to DE 43 35 848 A1, the disclosure content of which is to be included in full in this application for possible combinations of the solution according to the invention with known cooling arrangements.

In terms of the device, it is only necessary to assign the synchronous machine with transverse flow guidance only means for realizing the partial filling, in particular a coolant filling device.

The simplest way of realizing partial filling is to use the

To design the coolant sump in such a way that the stator is completely immersed in the radial direction in the region of a perpendicular to the axis of rotation below the rotor over part of its extent in the circumferential direction and thus the radial outer space between the stator and the rotor is partially filled in such a way that the rotor is inoperative in the vertical direction at least partially in the

Immersed coolant sump. The coolant is preferably filled as a constant filling before the synchronous machine is put into operation for the first time and later for replacement after the old coolant has been emptied at specific, preferably predefined or freely selectable time intervals. For filling, it is only necessary that a) on the end faces of the housing of the synchronous machine and / or b) in the element supporting the outer stator in the region of its end face or on the circumference closable through openings and / or channels are provided, which a space outside the radial outer space between the rotor and

Connect the outer stator and the radially outer space to each other and to which a coolant source can be connected. The achievement of the object according to the invention is explained below with reference to a figure. FIGS. 1a and 1b illustrate the basic principle of the method according to the invention in two views on the basis of a sectional illustration of a transverse flux machine.

FIG. 1 a uses a section from an axial section of a synchronous machine 1 with a transverse flux guide to illustrate the structure of a stator unit 2 designed for the solution according to the invention. This has at least one stator unit 4 carrying at least one armature winding 3. This is designed as an element of the overall internal stator assembly. The stator unit 4 is arranged in a stator housing 5. In the housing 5, a rotor 6 of the synchronous machine 1 with a transverse flow guide is also rotatably mounted. The stator assembly 2 further comprises a second stator unit 8, which functions as an external stator 7. This comprises a plurality of individual stator elements 9.1 to 9.n arranged one behind the other in the circumferential direction, which in the axial section according to FIG. 1a also have an essentially U-shaped cross section, however, at least are designed as tooth elements or teeth 15 supporting elements. The stator elements 9.1 to 9.n form with the outer surface 10 of the rotor 6 in

Installation position or assembled state of the synchronous machine 1 an air gap 11, which is also referred to as a radially outer space. The stator unit 8 is preferably free of an armature winding. The individual stator elements 9.1 to 9.n are arranged one behind the other in the circumferential direction at a certain distance from one another. These thus form spaces 12.1 to 12.n.

These spaces are connected to the radially outer space 11 between the rotor 6 and the outer stator 8. The rotor G comprises a central carrier disk 17 and at least one, preferably two pole structures extending in the axial direction from the carrier disk 17, shown here a pole structure 18, each comprising two rows, from in

Circumferentially arranged and alternately magnetized magnet arrangements with soft iron elements in between. For the Pole structure 18 shown, the rows are designated 19 and 20. The magnet arrangements of the series 19 are designated by 21. The series 19 soft iron units are designated 22 in this view. The magnet arrangements of the series 20 are designated by 23 and the soft iron elements by 21. The rows 19 and 20 are each by an intermediate layer, here the

Liner 25 made of magnetically and electrically non-conductive material separated from each other. The radially outer dimensions of the magnet arrangements 21 and 23 and the soft iron elements 22 and 24 arranged between them are different and thus produce a structure of the rotor G which is stepped in the circumferential direction and thus an uneven outer surface on the outer circumference 14 of the rotor. TA21, TA 23 for the magnet arrangements of both rows 19 and 20 and τ _A 22 and τ _A 24 for the soft iron elements 22 and 24 of rows 19 and 20 are shown.

The embodiments shown in FIGS. 1a and 1b describe a particularly compact configuration of a stator assembly 2, in particular a stator unit in the form of an outer stator. This enables a large surface area due to the circumferentially aligned end faces of the individual stator elements 9.1 to 9.n, which can be used completely for cooling purposes and for generating the coolant-air mixture, depending on the fastening. The individual individual stator element 9.1 to 9.n is designed as an element with a broadened back, which is preferably produced by powder metallurgy, that is to say pressed and is therefore produced in one piece. The individual stator element is designed as a full part and is preferably only connected to the stator housing 5 in a non-positive and positive manner by means of connecting elements.

In the simplest case, the stator housing comprises an annular housing part. The fastening elements are guided through the housing wall of the ring-shaped housing part and brought into operative connection with corresponding counter elements on the individual stator elements. In the simplest case, each individual stator element 9.1 to 9.n has at least one thread machined into it. The thread extends from the outer surface facing away from the rotor in the direction of the rotor 6. Others Connections that are easy to implement, for example by clamping, are also possible.

The synchronous machine 1 with transverse flow guidance are here means not shown in detail for filling the interior 16 with a

Assigned coolant. The interior 16 is filled at least over a portion of the outer spaces 11 in the radial direction. The coolant level 13 which is set when not in operation is at least touched by the outer circumference 14 of the rotor 6, preferably this is partially immersed therein. When the synchronous machine is started up, the coolant is replaced by the

Rotation and the stepped structure of the rotor 6 entrained and atomized due to the forces acting on the coolant. Basically, depending on the speed of the rotor shaft and the filling level, a coolant-air mixture is created in the space between the rotor 6 and the stator 2. This takes over through heat distortion and heat transfer

Heat transport from the rotor 6 to the stator 8. Because of the interstices 12.1 to 12.n caused by the stator construction, the available stator area, in particular on the outer stator, is considerably enlarged, which on the one hand favors the atomization and on the other hand also with respect to the possible cooling which Heat emission available surface increased considerably. Since the coolant-air mixture essentially only takes on the heat transport, it is not necessary to provide additional devices for cooling the coolant. A single partial filling with coolant, which remains inside the synchronous machine, is sufficient.

The external stator 7 can be cooled, for example, via cooling channels (not shown) in the housing 5. Other options are possible. LIST OF REFERENCE NUMBERS

1 synchronous machine with transverse flow control

2 stator assembly

3 armature winding

4 stator unit

5 housing

6 rotor

7 outer stator

8 second stator unit

9.1 - 9.n individual stator elements

10 outer surface 10

11 air gap

12.1 - 12.n gaps

13 coolant level

15 tooth bearing elements

16 interior

17 central carrier disc

18 pole structure

19 row

20 row

21 magnet arrangement

22 soft iron elements

23 magnet arrangements

24 soft iron elements

25 liner

Claims

claims

1. A method for cooling a synchronous machine with transverse flow guidance with a rotor having a stepped outer surface in the circumferential direction on the outer circumference and at least one outer stator, which form a space in the radial direction with one another, the outer stator comprising a plurality of individual elements arranged at certain distances from one another in the circumferential direction and is free of an armature winding; 1.1 in which at least a portion of the outer stator is cooled;

1.2 in which the interior of the synchronous machine is partially filled with a coolant such that

1.2.1 a coolant sump is formed in the non-operating position in the installed position, the mirror of which lies at least in the region of the area below the axis of rotation of the rotor of the synchronous machine

Sets the space between the rotor and outer stator, the rotor being immersed in the coolant sump in this operating state;

1.2.2 when the synchronous machine is in operation, the coolant is entrained by the rotor rotation of the resulting negative pressure and is atomized in the spaces between the individual elements, a coolant-air mixture being formed.

2. The method according to claim 1, characterized in that an oil with low viscosity is used as the coolant.

3. The method according to any one of claims 1 or 2, characterized in that the coolant remains in the interior in a closed system without circulation and the interior is kept free of a hermetic seal.

4. The method according to any one of claims 1 to 3, characterized in that the coolant after filling a predefined or freely selectable Period remains in the synchronous machine and is exchanged after a predefined or freely selectable period.

5. The method according to any one of claims 1 to 4, characterized in that the outer stator is additionally cooled.

6. The method according to claim 5, characterized in that a cooling medium is passed through the wall of the stator housing and / or along its outer circumference.

7. synchronous machine with transverse flow guidance;

7.1 with a rotor, the outer surface of which is not stepped on the outer circumference in the circumferential direction;

7.2 with a stator assembly comprising at least one outer stator and a stator housing assigned to the stator unit;

7.3 with at least one cooling device which is assigned to the outer stator;

7.4 rotor and outer stator form a gap in the radial direction;

7.5 means are provided for filling a portion of the space between the rotor and the outer stator with coolant; 7.6 the outer stator assigned to the rotor in the radial direction comprises in

Circumferential direction a plurality of individual elements arranged at certain distances from one another, which are assigned to the rotor in a corresponding complementary manner.

8. synchronous machine with transverse flow guidance according to claim 7, characterized in that the individual elements are formed in a strip shape.

9. synchronous machine with transverse flow guidance according to claim 7 or 8, characterized in that the uneven outer surface of the rotor is generated by changing radial dimensions alternately in the circumferential direction.

10. Synchronous machine with transverse flow guidance according to one of claims 7 to 9, characterized by the following features:

10.1 with at least one pole structure arranged on a central carrier disk and extending in the axial direction;

10.2 each pole structure comprises two rows of soft iron elements which are separated from one another by an intermediate layer and magnet arrangements arranged and alternately magnetized therebetween; 10.3 the uneven outer surface is characterized by different radial outer surfaces

Dimensions of the magnet arrangements and the soft iron elements arranged between them.

11. Synchronous machine with transverse flow guidance according to one of claims 7 to 10, characterized in that the individual elements are made of powder metallurgically manufactured and pressed materials and are connected by means of fastening elements to the stator housing.

12. Synchronous machine with transverse flow guidance according to one of claims 7 to 11, characterized in that the connection between the individual elements of the outer stator and the stator housing is realized by screw connections.

13. Synchronous machine with transverse flow guidance according to one of claims 7 to 12, characterized in that the individual elements

Form or carry number elements.

14. Synchronous machine with a transverse flow guide according to claim 13 to 11, characterized in that the tooth elements of a single element are arranged offset to one another in the circumferential direction.

15. synchronous machine with transverse flow guidance according to claim 13, characterized in that the tooth elements of a single element are arranged in the circumferential direction in one plane.

16. Synchronous machine according to one of claims 7 to 15, characterized by the following features:

16.1 with a stator housing;

16.2 the means for filling the intermediate space comprise a feed channel which is connected to the interior of the housing and can be closed and can be coupled to a coolant device.

17. Synchronous machine according to one of claims 7 to 16, characterized in that the cooling device assigned to the outer stator comprises at least one channel which can be filled with a cooling medium and is arranged in the stator housing.