EP3210286A1

EP3210286A1 - Electric machine designed as a disc-rotor comprising a cooling channel arrangement

Info

Publication number: EP3210286A1
Application number: EP15756923.7A
Authority: EP
Inventors: Patrick Fruehauf
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2014-10-24
Filing date: 2015-09-01
Publication date: 2017-08-30
Also published as: WO2016062438A1; DE102014221648A1

Abstract

An electric machine (1) is described, which can be designed, in particular, as a disc-rotor. The electric machine (1) comprises a stator (3), a rotor (5) and a cooling channel arrangement (9) on the stator (3). Heat-generating components (4), for example in the form of coils (8), are provided on the stator (3). The rotor (5) can be rotated relative to the stator (3) and is spaced apart therefrom by an air gap (7). The cooling channel arrangement (9) comprises a cooling channel (11) through which a cooling fluid can flow in the circumferential direction (13) along the stator (3). The electric machine (1) is characterized in that the cooling arrangement (9) extends both along an outer surface (15) of the heat-generating components (4) of the stator (3) on the opposite side to a surface (17) of the stator (3) adjacent to the air gap (7), and also along at least one, preferably both, opposite lateral surfaces (19) of the stator (3), extending transversely to said surface (17) and up to the air gap (7). Owing to such a cooling channel arrangement (9), having an L-shaped or U-shaped cross-section, the heat-generating components (4) can also be efficiently cooled on the sides thereof up to the areas close to the air gap (7). The cooling channel arrangement (9) can advantageously have a two-part design, wherein a first part (21) can be made, for example, as a die-cast component, from a good thermally conductive metal and a second component (23), acting as a lid, can be closed. Webs (29) or turbulence elements (31) can provide improved cooling power inside the cooling channels (11).

Description

title

AS DISC OPERATOR ELECTRIC MACHINE WITH

COOLING CHANNEL ARRANGEMENT

Field of the invention

The invention relates to an electrical machine, which may be designed in particular as a pancake and in which a Kühlkanalanordnun is advantageously formed.

Background of the Invention Electric machines can be used as motors or generators for a variety of applications

Purposes are used. In particular, electrical machines in electric or hybrid vehicles can serve as a drive or for recuperation of kinetic energy. An electric machine points

typically a stator and a rotatable relative to this stator rotor.

In an electric machine, electrical energy is converted into kinetic energy or vice versa. Any losses that occur lead to heating of components of the electrical machine during their operation. In order to avoid excessive heating of these components, a cooling arrangement should be provided in the electrical machine.

In conventional electric machines, the stator is often cooled by means of a liquid or gaseous cooling fluid. On the stator can be provided for this purpose a cooling channel through which the cooling fluid is flowed.

For example, the cooling channel can run in such a way that the cooling fluid flows in the circumferential direction along the stator. Usually, the cooling channel is located at the back of the stator, that is, at an outward and thus opposite to a surface facing the rotor

located side of the stator. Alternatively, stator windings can also be designed as waveguides, by means of which cooling can be realized.

DE 10 2013 206 021 AI and DE 10 2013 206 017 AI describe a

Transverse flux machine in 2-phase design or an asynchronous transverse flux machine with cooled stator.

Disclosure of the invention

Embodiments of the present invention may advantageously enable an electric machine, in particular an electric machine designed as a disk rotor, to be suitably designed

To cool the cooling channel arrangement efficiently. In particular, the

Cooling duct arrangement and provided with this cooling channel arrangement stator are easily manufactured or assembled.

According to one aspect of the present invention, an electric machine is proposed, which has a stator, a rotor and a cooling channel arrangement on the stator. The stator has heat generating components disposed therein. The rotor is rotatable relative to the stator and spaced therefrom by an air gap. The cooling channel arrangement has a

Cooling passage through which a cooling fluid in the circumferential direction along the stator can be flowed. The electric machine is characterized in that the cooling channel arrangement extends both along an outer surface of the

heat generating components of the stator opposite to an air gap adjacent surface of the stator and at least one extending transversely to this surface and toward the air gap side surface of the stator extends.

Ideas for embodiments of the present invention may be considered, inter alia, as being based on the thoughts and findings described below.

As noted in the introduction, in conventional electric machines, the stator is usually cooled only on an outside opposite the side of the air gap. Stator windings, which during operation of the electric machine as active parts, ie as heat-generating components, act and where a large part of the total dissipated in the electric machine waste heat, are relatively far from one

Cooling channel removed and often only by poor thermal conductivity materials such as insulation materials, for electrical insulation of the

Serve stator windings, tied. In particular, the insulation materials used can also be sensitive to high temperatures. Thus, since the insulating materials can be damaged at high temperatures, a power density of such electric machines can be narrow

Be limited.

It is therefore proposed to provide on a stator of an electric machine, an improved cooling channel arrangement, which increased

Heat dissipation can allow in particular from heat-generating components of the stator. As a heat-generating components of the stator can primarily coils or stator windings

be considered. But in other components of the stator, such as to be magnetized ferromagnetic areas of the stator can lead to losses and thus to heat generation.

It is proposed that the cooling channel arrangement not only extend along an outer surface of the heat-generating components of the stator, that is, a surface opposite to an air gap adjacent surface of the stator, but also extend along one or preferably both opposite side surfaces of the stator should. Such a cross-sectionally, for example, L-shaped or U-shaped cooling channel arrangement, the stator and in particular its heat-generating components not only only from the outer surface but also from at least one or preferably of both

Side surfaces are cooled down. The described cooling channel arrangement can thus enable efficient cooling of the stator and in particular of the windings provided therein with only one integrated cooling channel.

In particular, it may be advantageous for the cooling channel arrangement to extend along at least one side surface of the stator up to the air gap.

In other words, portions of the cooling channel assembly may extend from the outer surface of the stator along at least one of the side surfaces to an inner surface of the stator adjacent the air gap extend. Thus, heat-generating components can be cooled efficiently, particularly in this region adjacent to the air gap, that is, where the strongest heat generation frequently occurs during operation. Indirectly, even the rotor or a surrounding medium can be cooled.

In an advantageous embodiment, the cooling channel arrangement may be composed of at least two components. The two components can be easily manufactured and later assembled to form the cooling channel arrangement.

In particular, it can be advantageous for the cooling channel arrangement to be composed of a first part which forms a channel that is L-shaped or U-shaped and outwardly open, and a second part which closes off the area of the first component that is open to the outside. The im

Cross-section L-shaped or U-shaped and open on one side first component can be easily manufactured. In particular, this first component can be easily die-cast. This makes it possible to produce the first component of the cooling channel arrangement easily and with low manufacturing tolerances. In a state mounted on the stator, the first component open towards the outside can then be closed to the outside with a suitably designed second component, in order in this way to produce a sealed cooling channel through which cooling fluid can flow during operation. The first and the second component can in principle consist of different

Materials exist. For example, the first component may consist of a metal, whereas the second component may be made of plastic, for example, and thus may be provided inexpensively as an injection molded part. However, it may be advantageous to make the same components

or to develop similar behaving materials, for example, any problems due to different

To avoid thermal expansion coefficient.

It may be advantageous to form at least partial regions of the cooling arrangement, which adjoin heat-generating components of the stator, from a material having good thermal conductivity. In particular, these portions may consist of a metal such as aluminum. A good

Thermal conductivity of the cooling channel arrangement in these sub-areas can contribute to efficient heat dissipation from the stator of the electric machine. Under a good heat conductive material can in this

Connection a material are understood, which has a thermal conductivity of preferably more than 50 W / (m K), in particular more than 100 W / (m K) or more than 200 W / (m K).

In particular, the above-mentioned first component of a two-part cooling channel arrangement can be designed in such a way that it adjoins heat-generating components of the stator at least in regions, and consist of a material having good thermal conductivity, in particular a metal.

The first component can thus be easily manufactured, for example, die-cast, and thereby for a particularly good heat dissipation from the

provide heat generating components. Alternatively to a two-part embodiment described above, the

Cooling channel arrangement also be formed in one piece. For example, a cooling channel arrangement can be constructed from a part using a lost-form method. In such an embodiment or in a structure constructed of two parts, the area to be sealed needs the

Cooling channel arrangement in principle not be larger than conventional

Cooling channels in electrical machines.

It may be advantageous to arrange webs running transversely to the circumferential direction of the stator in the cooling channel of the cooling channel arrangement. The webs may partially protrude into the cross section of the cooling channel or this

Cooling channel in a direction parallel to the circumferential direction of the stator in

Block portions so that passed through the cooling passage cooling fluid can not flow unhindered along the circumferential direction of the stator through the cooling passage, but is at least partially deflected by the webs. Preferably, the webs are formed and arranged such that the

Cooling fluid is meander-like passed through the cooling channel arrangement. As a result, an overall increased cooling capacity can be achieved. In addition, it can be effected that cooling fluid flows through as far as possible all areas of the cooling channel and thus a spatially homogeneously distributed cooling capacity can be achieved.

It may also be advantageous to form turbulence elements in the cooling channel for swirling a cooling fluid flow. Such swirling elements For example, may be local projections, which protrude into the cross section of the cooling channel. Due to the turbulence caused by the cooling fluid flow, an increased cooling capacity can be achieved. In some cases, the above-mentioned transverse to the circumferential direction

extending webs serve as swirling elements.

The cooling channel arrangement may advantageously have a rotationally symmetrical structure. In particular, in such a rotationally symmetrical structure, a position of terminals, by the cooling fluid in the of the

Cooling channel formed cooling channel can be added or removed, be set or positioned at different angles.

The cooling channel arrangement proposed herein may be used for different types of electrical machines and adapted as appropriate.

Particularly advantageously, the cooling channel arrangement can be used for a designed as a disc rotor electrical machine. A pancake can be an electric motor or generator whose rotor has a shape of a disk. Current-carrying windings may for example be mounted on the disk, but the rotor typically does not contain an iron core. For disc travelers, the diameter is typically greater than an axial length. Disk runners are often designed as axial flow machines, that is, a magnetic flux extends in a wide range parallel to an axis of rotation of the electric machine. Alternatively, however, a pancake may also be designed as a transverse flux machine.

It should be understood that some of the possible features and advantages of the invention are described herein with reference to different embodiments. A person skilled in the art will recognize that the features can be suitably combined, adapted or replaced in order to arrive at further embodiments of the invention.

Brief description of the drawings

Embodiments of the invention will now be described with reference to the accompanying drawings, in which neither the drawings nor the description are to be construed as limiting the invention. Fig. 1 shows a perspective view of a trained as a disc rotor electrical machine.

2 shows a perspective sectional view from the outside through a stator of an electric machine according to the invention.

Fig. 3 shows a perspective, partially cut away sectional view from the outside through a stator of an electric machine according to the invention.

Fig. 4 shows a perspective sectional view from the inside through a stator of an electric machine according to the invention.

The figures are only schematic and not to scale. Like reference numerals in the figures designate the same or equivalent

Characteristics.

Embodiments of the invention

FIG. 1 shows an electric machine 1 embodied as a disk rotor. An annular stator 3 and a likewise annular rotor 5 are arranged next to one another in the axial direction, that is to say along a rotation axis 6. The stator 3 and the rotor 5 have approximately the same diameter and are both arranged coaxially with the axis of rotation 6. Between the stator 3 and the rotor 5, an air gap 7 extends.

In Figures 2, 3 and 4, a structure of a stator 3 based on

shown in perspective sectional views.

Adjacent to the air gap 7, the stator 3 has a plurality of coils 8, which are arranged side by side along the circumference of the stator 3. Each of the coils 8 has windings 10 made of wires, which are wound on a base body 12. In the case of an electric machine 1 designed as a disk rotor, an axis about which the windings 10 are wound can run parallel to the axis of rotation 6 of the electric machine 1.

During operation of the electric machine 1, a time-varying magnetic field is generated by energizing the windings 10, by means of which then the rotor 5 is set in rotation. In particular, due to occurring electrical losses in the windings 10 and magnetic losses in the bodies 12, this can lead to significant local warming, so that the coils 8 can be considered as heat-generating components 4 of the stator 3.

In order to be able to cool these heat-generating components 4 efficiently, a cooling channel arrangement 9 is provided on the stator 3. The cooling channel arrangement 9 has a cooling channel 11, through which a cooling fluid such as water or oil or a cooling gas can be flowed substantially in the circumferential direction 13 along the stator 3.

The cooling channel arrangement 9 is designed with a specially adapted geometry. Portions of the cooling arrangement extend along an outer surface 15 of the heat-generating components 4 of the stator 3, this outer surface 15 extending opposite or opposite to a surface 17 of the stator 3 adjoining the air gap 7. These portions of the cooling channel assembly 9 mainly cool one

Rear side of the heat-generating components 4. However, the cooling channel arrangement 9 also has further subregions which extend in the illustrated example along both opposite side surfaces 19 of the stator 3. These side surfaces 19 are arranged transversely to the surface 17 adjacent to the air gap 7. The entire cooling channel 11 of the cooling channel arrangement 9 thus has in

illustrated example in cross-section on a U-shape. The two lateral limbs of the "U" encompass the heat-generating components 4 from the sides and extend there substantially as far as the air gap 7. Accordingly, the coils 8 acting as heat-generating components 4 are not only at their outwardly directed rear side, but also at its radially inward, that is towards the axis of rotation 6, directed

Side surface 19 and at the opposite, radially outwardly facing side surface 19 in contact with portions of the cooling channel assembly 9 or at least closely adjacent to these, and thus can be efficiently cooled.

In the example shown, the cooling channel arrangement 9 is composed of two components 21, 23. A first component 21 essentially has a U-shape, however, alternatively could have an L-shape in another embodiment. This first component may advantageously consist of a good thermal conductivity material such as aluminum. Due to its relatively simple geometry and its design, which essentially requires no undercuts, the first component 21 can be simple

be die-cast. On a side directed towards the outer surface 15, the first component 21 is open and thus forms an outwardly open channel 25 towards this side. In order to close this channel 25, a second component 23 in the form of a second component 23 is formed

Cover attached to the first component 21. Edges of the two components 21, 23 are fluid-tightly connected to each other, so that the channel 25 is hermetically sealed. By supplying and discharging ports (not shown), a cooling fluid can be circulated through the cooling passage 11.

FIG. 3 illustrates an internal structure of the cooling channel arrangement 9 without a covering second component 23 acting as a cover. In its interior, that is to say in its cooling channel 11, the cooling channel arrangement 9 has webs 29 which run transversely to the circumferential direction 13. The webs 29 extend on the one hand along the on the outer surface 15 of the heat-generating

Components 4 adjacent portions of the first component 21. In this case, the webs 29 are arranged approximately perpendicular to the circumferential direction 13 in this area. On the other hand, parts of the webs 29 also extend within the lateral limbs of the U-shaped cooling channel arrangement 9, that is parallel to the axial direction 14. Along the circumferential direction 13, a plurality of such webs 29 are arranged, each individual web each with only a portion in a the lateral leg of the cross-sectionally U-shaped first member 21 extends, whereas an opposite lateral leg without local web 29 remains. The webs 29 are alternately formed so that an axially extending portion of a first web 29 extends in an outer leg, whereas an axially extending portion of an adjacent web 29 in a radially inner leg of the U-shaped first member 21 extends.

In this way, 11 of the webs 29 each within the cooling channel constructed barriers which force a flowing cooling fluid to flow along a meandering path through the cooling channel 11. One such meander-shaped path is illustrated by the arrow 16. A meandering of the cooling fluid flow caused thereby can considerably increase a cooling capacity of the cooling channel arrangement 9. On the one hand, the webs 29 can cause the cooling fluid as possible in all

Regions of the cooling channel 11 flows and receives heat there. On the other hand, can be increased by the webs 29, a surface of the cooling channel 11. In addition, the webs 29 may act as the cooling channel assembly 9 stiffening.

In order to further increase a cooling capacity, 11 are in the cooling channel

Verwirbelungselemente 31 provided. In the example shown, these swirling elements 31 are designed as projections projecting into the interior of the cooling channel 11, around which a cooling fluid flowing through is deflected and in that case preferably swirled.

In summary, an electric machine is presented in which a cooling channel arrangement has a special, for example U-shaped or L-shaped cooling channel geometry. A cooling channel protrudes in the radial direction and the axial direction inwards and outwards via heat-generating

Components, that is, active parts of the stator, out and continues to run in the axial direction towards the air gap. The special cooling channel geometry enables simultaneous cooling of the stator and the stator coils. The cooling channel arrangement can be constructed in one or two parts. In particular, in a two-part structure, individual components can be easily manufactured, for example, die-cast, and then connected to each other. Despite enclosing cooling can thereby only small

Be necessary sealing surfaces. Verwirbelungselemente within the cooling channel and webs, which can cause a coolant flow in meandering paths, can increase a cooling capacity. Due to the hereby possible improved cooling of the heat-generating components of the stator, a higher power density of the active parts,

especially at continuous power to be achieved. In addition, due to the overall cooler components of the electric machine overall, a higher efficiency for these can be achieved.

Finally, it should be noted that terms such as "comprising", "comprising", etc. do not exclude other elements or steps and Terms such as "one" or "one" do not exclude a multitude. It should also be appreciated that features or steps described with reference to any of the above embodiments may also be used in combination with other features or steps of others described above

Embodiments can be used. Reference signs in the claims are not to be considered as limiting.

Claims

Electric machine (1), comprising:

a stator

(3) with heat-generating components arranged therein

(4),

a rotor

(5) rotatable relative to the stator (3) and spaced therefrom by an air gap (7);

a cooling channel arrangement (9) on the stator (3), which has a cooling channel (11) through which a cooling fluid can flow in the circumferential direction (13) along the stator (3);

characterized in that

the cooling channel arrangement (9) extends both along an outer surface (15) of the heat-generating components (4) of the stator (3) opposite to a surface (17) of the stator (3) adjacent to the air gap (7) and along at least one transversely this surface (17) and towards the air gap (7) extending side surface (19) of the stator (3).

Electrical machine according to claim 1, wherein the cooling channel arrangement (9) extends along both opposite side surfaces (19) of the stator (3).

Electric machine according to claim 1 or 2, wherein the

Cooling channel arrangement (9) extends along at least one side surface (19) of the stator (3) up to the air gap (7).

Electric machine according to one of claims 1 to 3, wherein the

Cooling channel arrangement (9) made of at least two components (23)

is composed.

Electrical machine according to one of claims 1 to 4, wherein the

Cooling channel arrangement (9) consisting of a first component (21), which forms a channel (25) which is L-shaped or U-shaped in cross section and is open to the outside, and a second component (23), which forms the area (27) which is open to the outside. of the first component (21) closes like a lid, is assembled.

6. Electrical machine according to claim 5, wherein at least the first component (21) is a die-cast component.

7. Electrical machine according to one of claims 1 to 6, wherein at least partial areas of the cooling channel arrangement (9), which adjoin heat-generating components (4) of the stator (3), are made of a good

thermally conductive material, in particular a metal.

8. Electrical machine according to one of claims 1 to 7, wherein webs (29) running transversely to the circumferential direction (13) of the stator (3) are arranged in the cooling channel (11) of the cooling channel arrangement (9).

9. Electrical machine according to one of claims 1 to 8, wherein in the cooling channel (11) swirling elements (31) for swirling a

Cooling fluid flow are formed.

10. Electrical machine according to one of claims 1 to 9, wherein the

Cooling channel arrangement (11) has a rotationally symmetrical structure.

11. Electrical machine according to one of claims 1 to 10, which

Disc rotor is designed.