The present invention relates to a device,
Such devices are generally known. Virtually any conventional electric motor which has a housing or is installed in a larger device in particular has such a design.
In the context of mobile applications, the power-to-weight ratio of electric motors is very important. In particular, attempts are made to reduce the weight of the electric motors as much as possible. It is desirable to reduce weight both in the case of the so-called active parts (i.e. the electromagnetically active components, i.e. magnets and windings and laminations or laminate stacks) and in the case of the remaining components, the so-called passive parts.
Attempts are generally made in the prior art to optimize the individual components of the systems. However, a particularly high degree of potential lies in integrative lightweight construction, for example by structural and functional integration of active and passive parts. The object of the present invention consists in providing a device comprising an electric machine with a lightweight design, in which such an integrative lightweight construction is realized.
The object is achieved by a device having the features of claim 1. Advantageous configurations of the device according to the invention are the subject matter of dependent claims 2 to 18.
In accordance with the invention, a device of the type mentioned at the outset is further developed in order to achieve the object in that
Owing to the first interlayers, the weight of the electric machine is considerably reduced in comparison with a conventional electric machine of the same physical size. The peak power that can be output by means of the electric machine according to the invention and which is limited by the magnetic saturation of the stator laminations is lower than in the case of the comparable conventional machine. The continuous power of the electric machine according to the invention, which is limited by the heat which can be dissipated from the stator stack, is virtually equal in size to that in the case of the conventional electric machine, however.
It is possible for in each case a first interlayer to be arranged between all of the stator laminations. Alternatively, it is possible for the first interlayers to only be arranged between some of the stator laminations. In this case, electromagnetically inactive second interlayers are preferably arranged between those stator laminations between which no first interlayer is arranged. The second interlayers are not part of the connecting structure. The cut of the second interlayers in this configuration generally corresponds to the cut of the stator laminations. Said second interlayers therefore have the same contour as the stator laminations.
In the case of the presence of the second interlayers, a predetermined number of second interlayers is arranged between in each case two first interlayers, wherein the number of second interlayers is generally always the same. It is possible for in each case a single second interlayer to be arranged between in each case two first interlayers. Preferably, however, in each case a plurality of second interlayers follow on from the first interlayers, when viewed in the direction of the axis of rotation.
The material of the first interlayers can be determined as required. Preferably, the first interlayers consist of a fiber composite material, for example from a carbon fiber-reinforced plastic (CFRP) or glass fiber-reinforced plastic (GFRP). The same applies, if present, to the second interlayers.
It is possible for the first interlayers to be used exclusively for fixing the stator stack, i.e. to exclusively implement the mechanical supporting function of the stator stack. Preferably, the first interlayers additionally provide a heat-conducting function, however. For this purpose, provision can be made in particular for the first interlayers to consist of a material which has a preferred heat-conducting direction. Such materials, in particular carbon fiber-reinforced plastics, are known to those skilled in the art. In the case of such a material, the preferred heat-conducting direction is preferably oriented radially or tangentially with respect to the axis of rotation within the stator stack and away from the stator stack outside of the stator stack.
It is possible for heat-dissipating elements such as cooling ribs or the like to be arranged on the connecting structure.
Preferably, provision is made for the connecting structure to have a number of substructures, the substructures each to have a central layer, which does not contain any of the first interlayers, and the central layers to be delimited on both sides in each case by a group of first interlayers, when viewed in the direction of the axis of rotation. By virtue of this configuration, a very stable connecting structure which can be subjected to loads results in a particularly simple manner.
The number of first interlayers per group of first interlayers can be as required. It is possible for the corresponding number to be equal to one. This can be expedient in particular when the second interlayers are present. Alternatively, it is possible for the corresponding number to be greater than one, for example three to six. This can be expedient in particular when no second interlayers are present, i.e. in each case a first interlayer is arranged between all stator laminations.
The central layers can be formed as required. For example, it is possible for the central layers to consist of a structural foam. Alternatively, the central layers can consist of a sandwich structure. In this case, the sandwich structure preferably has two covering layers and one honeycomb structure arranged between the covering layers.
In general, the connecting structure has at least two such substructures. It is possible for a single group of first interlayers to simultaneously adjoin the central layer of both substructures. Alternatively, it is possible for the mutually facing groups of first interlayers of the substructures to be spaced apart from one another, when viewed in the direction of the axis of rotation. In this case, the two substructures can delimit a cavity axially on both sides, for example. In this case, through-openings for feeding cooling medium into the cavity and for feeding the cooling medium out of the cavity are preferably arranged in the substructures. In particular in this configuration, the connecting structure is often formed over the full area tangentially, when viewed around the axis of rotation.
Alternatively, it is possible for the connecting structure to have a number of spoke-like connecting struts, which connect the stator stack to the basic body. In this case, the first interlayers are parts of the connecting struts.
In general, the connecting struts are flat. In this case, first interlayers are located at least on the upper side and the lower side of the (flat) connecting struts.
The connecting struts extend from the stator stack to the basic body in the direction of a respective main axis. In a preferred configuration of the present invention, provision is made for the connecting struts to be rotated about the respective main axis. As a result, the connecting struts can act as guide elements for cooling air, which is supplied to the connecting structure in the axial direction, i.e. in a direction parallel to the axis of rotation.
Alternatively, it is possible for the connecting struts to run in each case in a radial plane which is orthogonal to the axis of rotation, for the connecting struts to overlap a respective angular region, when viewed around the axis of rotation, for the connecting struts extending in the respective radial plane to only overlap part of a full circle, when viewed around the axis of rotation, per radial plane, and for the angular regions overlapped by the connecting struts extending in the respective radial plane to differ from one another with respect to at least two radial planes.
For example, a number of connecting struts which each overlap a specific angular region can be provided per radial plane. The connecting struts are generally arranged distributed uniformly within the respective radial plane. The connecting struts in the next radial plane can be offset with respect to the connecting struts in the first-mentioned radial plane by an offset angle, for example. The offset angle is preferably equal to or slightly less than the angular region. The whole process can be repeated for the subsequent radial plane, with the result that, when viewed over several radial planes, a coil-like configuration is gradually achieved. By virtue of such a configuration, the cooling effect of a cooling air flow supplied to the connecting structure can be optimized, for example.
Alternatively, it is possible for the connecting struts to extend from the stator stack to the basic body in the direction of a respective main axis and for the respective main axis to have, in addition to a component radial to the axis of rotation, a respective component axial to the axis of rotation. By virtue of this configuration, a particularly stable fixing of the stator stack relative to the basic body can be achieved in a particularly simple manner. This applies very especially when the respective main axis additionally has a respective component tangential to the axis of rotation. Such a spoke-like structure is a generally known approach in the case of wheels of bicycles and motorbikes, for example.
The present invention can be realized irrespective of whether the rotor is in the form of an internal rotor or an external rotor. All of the advantages of the present invention are shown, however, when the rotor is in the form of an external rotor. The device according to the invention can moreover be designed as required. Particularly preferred, however, is an application in the field of aeronautics, i.e. when the basic body is part of an aircraft, in particular a helicopter.
The above-described properties, features and advantages of this invention and the way in which said properties, features and advantages are achieved will become clearer and more easily comprehensible in connection with the following description of the exemplary embodiments, which will be explained in more detail in conjunction with the drawings, in which, as schematic illustrations:
As shown in
An electric machine 2 is arranged in the basic body 1. The electric machine 2 drives a generator set 3 of the device. In particular, the electric machine 2 can be in the form of the main drive for the device. In the case of an aircraft, the generator set 3 is in the form of an airscrew generating propulsion and/or uplift. The word “rotor” in this context is avoided intentionally because it is required later as such in connection with the electric machine 2.
As shown in
Where the terms “axial”, “radial” and “tangential” are used below, they always relate to the axis of rotation 7. Axial is a direction parallel to the axis of rotation 7. Radial is a direction orthogonal to the axis of rotation 7 towards the axis of rotation 7 or away from the axis of rotation 7. Tangential is a direction orthogonal to the axis of rotation 7 and orthogonal to the radial direction. Tangential is therefore a direction which is directed in the form of a circle around the axis of rotation 7 with a constant radial spacing and a constant axial position.
The stator stack 4 is fixed relative to the basic body 1 by means of the connecting structure 5. The stator stack 4 is therefore fixed both radially and axially relative to the basic body 1 by means of the connecting structure 5 and is furthermore also fixed in such a way as to prevent rotation about the axis of rotation 7.
As shown in
As shown in
In the configuration shown in
The first interlayers 10 consist of a material which is electromagnetically inactive. For example, the first interlayers 10 can consist of a fiber composite material. Suitable fiber composite materials are, for example, carbon fiber-reinforced plastics or glass fiber-reinforced plastics. The second interlayers 11, if provided, are also electromagnetically inactive. They can, but do not need to, consist of the same material as the first interlayers 10.
According to the configuration shown in
It is possible for the first interlayers 10 to consist of a material which has a preferred heat-conducting direction. For example, some carbon fiber-reinforced plastics have such a property. If the first interlayers 10 consist of such a material, the preferred heat-conducting direction is preferably oriented radially or tangentially to the axis of rotation 7 within the stator stack 4 and away from the stator stack 4 outside of the stator stack 4.
In the configuration shown in
In the configuration shown in
It is possible for heat-dissipating elements to be arranged on the connecting structure 5. Preferably, however, the connecting structure 5 itself is already in the form of a cooling device for the stator stack 4.
As shown in
As shown in
The number of first interlayers 10 per group of first interlayers 10 can be selected as required. It can be 1 (see
In general, a plurality of substructures 14 is provided. It is possible for the substructures 14 to merge with one another, when viewed in the direction of the axis of rotation 7, i.e. for a group of first interlayers 10 to simultaneously adjoin two central layers 15. Purely by way of example, this is illustrated in
Through-openings 21 for feeding a cooling medium into the cavity 20 and for feeding the cooling medium out of the cavity 20 can be arranged in the substructures 14. The cooling medium is preferably a liquid cooling medium, for example water. The arrangement of the through-openings 21 is preferably such that the cooling medium flows over the first interlayers 10 over their entire area. For example, the through-openings 21 corresponding to the illustration in
In accordance with a further configuration, the connecting structure 5 shown in
In the configuration shown in
In the configuration shown in
The offset angle γ can be selected as required. It is possible for the offset angle γ to be (slightly) less than the overlap angle α, for example approximately 25°. Alternatively, it may be equal to the overlap angle α or even greater than the overlap angle α.
As shown in
Even in the case of the illustration shown in
The present invention has many advantages. In particular, by virtue of the integration of active and passive parts by means of the first interlayers 10 of the connecting structure 5, a relatively simple, inexpensive and very lightweight solution for an electric machine 2 can be provided, whose performance potential during continuous operation can be maintained virtually to the full extent in comparison with a conventional electric machine.
Although the invention has been illustrated and described in detail by the preferred exemplary embodiment, the invention is not restricted by the examples disclosed and other variations can be derived herefrom by a person skilled in the art without departing from the scope of protection of the invention.
Number | Date | Country | Kind |
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12184238.9 | Sep 2012 | EP | regional |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2013/068177 | 9/3/2013 | WO | 00 |