CRYOGENIC COOLING IN ELECTRICAL MACHINES

Abstract

The invention describes a rotor (17) of an electrical machine (13) having a first housing (1) and a second housing (2), which is arranged in the interior of the first housing (1) with a cavity (18) with respect to the first housing (1). A liquid cryogen (9) can be introduced into the second housing (2) through a first opening (4) formed on the second housing (2). The vaporised cryogen (10) can be introduced into the cavity (18) through a second opening (5) formed on the second housing (2). The vaporised cryogen (10) can flow out from the cavity (18) through a third opening (6) formed on the first housing (1). In addition, the invention describes an electrical machine (13), a device for cooling and an aircraft. The invention also relates to an associated method for cooling a rotor (17).

Claims

1. A rotor of an electrical machine, the rotor comprising: a first housing; a second housing arranged in an interior of the first housing, wherein a cavity is formed between the first housing and the second housing; a first opening formed at the second housing, a liquid cryogen being flowable through the first opening into the second housing; a second opening formed at the second housing, an evaporated cryogen being flowable through the second opening into the cavity; and a third opening formed at the first housing, the evaporated cryogen being flowable through the third opening out of the cavity.

2. The rotor of claim 1, further comprising: a fourth opening formed at the first housing, the fourth opening being in operative connection with the first opening such that the liquid cryogen is flowable into the second housing.

3. The rotor of claim 1, further comprising a structure, arranged in the cavity, that is configured to: permit a flow of the evaporated cryogen in an axial direction; and interrupt a flow of the evaporated cryogen in a radial direction, such that radially oriented convection cells are prevented.

4. The rotor of claim 3, wherein the structure is formed of coaxial rings or has a honeycomb structure.

5. The rotor of claim 1, wherein the liquid cryogen is liquid hydrogen.

6. An electrical machine comprising: a rotor comprising: a first housing; a second housing arranged in an interior of the first housing, wherein a cavity is formed between the first housing and the second housing; a first opening formed at the second housing, a liquid cryogen being flowable through the first opening into the second housing; a second opening formed at the second housing, an evaporated cryogen being flowable through the second opening into the cavity; a third opening formed at the first housing, the evaporated cryogen being flowable through the third opening out of the cavity; a fourth opening formed at the first housing, the fourth opening being in operative connection with the first opening such that the liquid cryogen is flowable into the second housing; and a rotary feedthrough having the first opening and the fourth opening.

7. A device for cooling a rotor of an electrical machine, the rotor comprising a first housing, a second housing arranged in an interior of the first housing, wherein a cavity is formed between the first housing and the second housing, the rotor further comprising a first opening formed at the second housing, a liquid cryogen being flowable through the first opening into the second housing, a second opening formed at the second housing, an evaporated cryogen being flowable through the second opening into the cavity, a third opening formed at the first housing, the evaporated cryogen being flowable through the third opening out of the cavity, and a fourth opening formed at the first housing, the fourth opening being in operative connection with the first opening such that the liquid cryogen is flowable into the second housing, the device comprising: a container that is in operative connection with the fourth opening and is configured to provide the liquid cryogen.

8. The device of claim 7, further comprising: at least one unit to be cooled that is coolable by the evaporated cryogen after the evaporated cryogen has left the first housing; at least one fuel cell or at least one combustion engine configured to use the evaporated cryogen as fuel after the evaporated cryogen has left the first housing; or a combination thereof.

9. An aircraft comprising: a device for cooling a rotor of an electrical machine, the rotor comprising a first housing, a second housing arranged in an interior of the first housing, wherein a cavity is formed between the first housing and the second housing, the rotor further comprising a first opening formed at the second housing, a liquid cryogen being flowable through the first opening into the second housing, a second opening formed at the second housing, an evaporated cryogen being flowable through the second opening into the cavity, a third opening formed at the first housing, the evaporated cryogen being flowable through the third opening out of the cavity, and a fourth opening formed at the first housing, the fourth opening being in operative connection with the first opening such that the liquid cryogen is flowable into the second housing, the device comprising: a container that is in operative connection with the fourth opening and is configured to provide the liquid cryogen.

10. The aircraft of claim 9, further comprising an electric or hybrid-electric aircraft propulsion unit.

11. The aircraft of claim 9, wherein the aircraft is an airplane.

12. The aircraft of claim 11, further comprising: the electrical machine comprising the rotor; a rotary feedthrough having the first opening and the fourth opening; and a propeller that is settable in rotation by the electrical machine.

13. (canceled)

14. The rotor of claim 2, further comprising a structure, arranged in the cavity, that is configured to: permit a flow of the evaporated cryogen in an axial direction; and interrupt a flow of the evaporated cryogen in a radial direction, such that radially oriented convection cells are prevented.

15. The rotor of claim 14, wherein the structure is formed of coaxial rings or has a honeycomb structure.

16. The electrical machine of claim 6, wherein the rotor further comprises a structure, arranged in the cavity, that is configured to: permit a flow of the evaporated cryogen in an axial direction; and interrupt a flow of the evaporated cryogen in a radial direction, such that radially oriented convection cells are prevented.

17. The electrical machine of claim 16, wherein the structure is formed of coaxial rings or has a honeycomb structure.

18. The electrical machine of claim 6, wherein the liquid cryogen is liquid hydrogen.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 shows a longitudinal section through one embodiment of a rotor of an electrical machine;

[0028] FIG. 2 shows a longitudinal section through one embodiment of a rotor of an electrical machine having a honeycomb structure in a cavity between housings;

[0029] FIG. 3 shows a longitudinal section through one embodiment of a rotor of an electrical machine having coaxial rings in the cavity between the housings;

[0030] FIG. 4 shows a cross section through one embodiment of a rotor of an electrical machine having a tube structure in the cavity between the housings;

[0031] FIG. 5 shows a cross section through one embodiment of a rotor of an electrical machine having coaxial rings in the cavity between the housings;

[0032] FIG. 6 is a block diagram of one embodiment of a device for cooling an electrical machine having a rotor, a container in operative connection, and a further unit to be cooled or a combustion unit; and

[0033] FIG. 7 shows a view of one embodiment of an airplane.

DETAILED DESCRIPTION

[0034] FIG. 1 shows a schematic illustration of exemplary cooling of a rotor 17 of an electrical machine in longitudinal section. FIG. 1 shows a first housing 1 that is outer relative to a second housing 2. The second housing 2 is located in an interior 19 of the first housing 1. The first housing 1 and the second housing 2 may each have a circular cylindrical shape, for example, and are may be arranged concentrically.

[0035] Between the first housing 1 and the second housing 2, there is a cavity 18. A torque transmission element 3 is formed on the first housing 1 and the second housing 2. This may be used to transmit rotation of the electrical machine to a propulsion unit (e.g., a propeller). A first opening 4 and a second opening 5 opposite the first opening 4 are located at the second housing 2, at end faces. A third opening 6 and a fourth opening 7 are located at the first housing 1, at an end face. The fourth opening 7 is in operative connection with the first opening 4 at the second housing 2 and is in the form of a rotary feedthrough 8.

[0036] Liquid cryogen 9 flows via the rotary feedthrough 8 into an interior 19 of the second housing 2. The liquid cryogen 9 may be hydrogen, for example. The liquid cryogen 9 warms up in the interior of the second housing 2 and becomes gaseous (e.g., gaseous cryogen 10). The gaseous cryogen 10 then leaves the second housing 2 through the second opening 5 and flows into the cavity 18 between the first housing 1 and the second housing 2.

[0037] In the cavity 18, the gaseous cryogen 10 takes up most of the heat flow entering from the warm outer first housing 1. The gaseous cryogen 10 then leaves the cavity 18 between the first housing 1 and the second housing 2 and may be fed to further uses. A pressure slightly above ambient pressure prevails in the cavity 18.

[0038] FIG. 2 shows an extension of FIG. 1. The extension, which is likewise shown in longitudinal section, contains a means (e.g., structure) arranged in the cavity 18. The structure includes a tube structure 11. Flow channels are present in a direction of the flowing gaseous cryogen 10 (e.g., in an axial direction of the rotor 17), but as little heat-conducting material and convection as possible is formed transversely to the axial direction in order to prevent heat transport from the outside to the inside through thermal bridges. Alternatively to the tube structure, a honeycomb structure, for example, may be provided.

[0039] FIG. 3 shows an alternative extension to FIG. 2 of the rotor according to FIG. 1. The extension, which is likewise shown in longitudinal section, includes a means (e.g., a structure) in the form of coaxial rings 12 arranged in the cavity 18. The coaxial rings 18 are arranged axially concentrically around the second housing 2 and have spacers (not shown) for support in the cavity 18 or against one another.

[0040] FIG. 4 shows the cross section belonging to FIG. 2. FIG. 2 shows the first housing 1, the second housing 2, the tube structure 11 arranged in the cavity 18, and the interior 19. Alternatively to the tube structure, a honeycomb structure, for example, may be provided.

[0041] FIG. 5 shows the cross section belonging to FIG. 3. FIG. 5 shows the first housing 1, the second housing 2, the coaxial rings 12 arranged in the cavity 18, and the interior 19.

[0042] The heat input from the warm outside wall to the hydrogen gas owing to radially oriented convection cells is prevented. This may be achieved, for example, by a tube structure 11 that is introduced into the annular gap and through which flow takes place (FIG. 2 and FIG. 4), by coaxial rings 12 (FIG. 3 and FIG. 5), or by a honeycomb structure, which prevent radial convection.

[0043] FIG. 6 shows a block diagram of a device for cooling an electrical machine 13 having a rotor 17 according to FIG. 1, FIG. 2, or FIG. 3, and a container 14 connected thereto for providing a liquid cryogen 9. The device also includes a further unit 20 to be cooled or a fuel cell/internal combustion engine 21.

[0044] FIG. 7 is a view of an electric or hybrid-electric airplane 15 as an example of an aircraft. The electric or hybrid-electric airplane 15 includes an electrical machine 13 (not shown). The rotor 17 (not shown) of the electrical machine 13 sets a propeller 16 in rotation.

[0045] Although the invention has been described and illustrated more specifically in detail by exemplary embodiments, the invention is not restricted by the disclosed examples, and other variations may be derived therefrom by a person skilled in the art without departing from the scope of protection of the invention.

[0046] The elements and features recited in the appended claims may be combined in different ways to produce new claims that likewise fall within the scope of the present invention. Thus, whereas the dependent claims appended below depend from only a single independent or dependent claim, it is to be understood that these dependent claims may, alternatively, be made to depend in the alternative from any preceding or following claim, whether independent or dependent. Such new combinations are to be understood as forming a part of the present specification.

[0047] While the present invention has been described above by reference to various embodiments, it should be understood that many changes and modifications can be made to the described embodiments. It is therefore intended that the foregoing description be regarded as illustrative rather than limiting, and that it be understood that all equivalents and/or combinations of embodiments are intended to be included in this description.