The invention relates to an electrical machine, particularly for a vehicle, and to a vehicle comprising such a machine.
An electrical machine of this type can generally be an electric motor or a generator. The electrical machine can be embodied as external rotor or as internal rotor.
A machine of the generic type is known from U.S. Pat. No. 5,214,325, for example. It comprises a housing, which surrounds an interior and which has a casing extending circumferentially in a circumferential direction of the housing and radially delimiting the interior, axially at one side a rear side wall axially delimiting the interior, and axially at the other side a front side wall axially delimiting the interior. A stator of the machine is fixedly connected to the casing. A rotor of the machine is arranged in the stator, wherein a rotor shaft of the rotor is mounted rotatably by way of a front shaft bearing on the front side wall.
The stator of a conventional electrical machine typically comprises stator windings, which are electrically energized during operation of the machine. This gives rise to heat which has to be dissipated in order to avoid overheating and associated damage or even destruction of the stator. For this purpose, it is known from conventional electrical machines to equip the latter with a cooling device for cooling the stator—in particular said stator windings. Such a cooling device comprises one or more cooling channels through which a coolant flows and which are arranged in the vicinity of the stator windings in the stator. Heat transfer from the stator windings to the coolant enables heat to be dissipated from the stator.
In this case, it proves to be disadvantageous that efficient heat transfer from the stator to the coolant flowing through the respective cooling channel is only associated with considerable structural complexity. However, this has a disadvantageous effect on the production costs of the electrical machine.
Therefore, it is an object of the present invention to provide an improved embodiment for an electrical machine in which this disadvantage is largely or evenly completely eliminated. In particular, the intention is to provide an improved embodiment for an electrical machine which is distinguished by improved cooling of the stator windings of the stator.
This object is achieved by means of the subject matter of the independent patent claims. The dependent patent claims relate to preferred embodiments.
Accordingly, the basic concept of the invention is to embed the stator windings of an electrical machine into a plastic composition composed of a plastic, in which are also provided a coolant distributor chamber and a coolant collector chamber for a coolant which absorbs the waste heat generated by the stator windings as a result of thermal interaction. In this case, the plastic is used as a heat transfer medium for transferring heat from the stator windings to the coolant.
A particularly good heat transfer between the stator windings and the coolant passed through the stator is produced in this way. This holds true particularly if a plastic having a high thermal conductivity is used. So-called thermosetting plastics, in particular, are suitable for this purpose. Since a plastic typically also has the properties of an electrical insulator, at the same time this ensures that the stator windings to be cooled are not electrically short-circuited in an undesired manner by the plastic. Consequently, even in the case of high evolution of waste heat in the stator, such as occurs for example during operation of the electrical machine under high load, it can be ensured that the waste heat that arises can be dissipated from the stator. Damage or even destruction of the electrical machine as a result of overheating of the stator can thus be avoided. The plastic composition—essential to the invention—with the coolant distributor chamber and/or respectively coolant collector chamber formed therein can be produced by means of injection molding, in the course of which the plastic is injection-molded around the stator windings to be cooled. The embedding of the stator windings and the cooling channel into the plastic composition therefore turns out to be very simple.
For the purpose of cooling the stator windings, the coolant proceeding from the coolant collector chamber embodied in the plastic composition can be distributed among a plurality of cooling channels in which the coolant absorbs waste heat from the stator windings as a result of thermal interaction. After flowing through the cooling channels, the coolant can be collected in the coolant collector chamber. Since the coolant distributor chamber and the coolant collector chamber are arranged in the plastic composition according to the invention, the coolant present in the coolant distributor chamber can be used for cooling the stator winding already before being distributed among the cooling channels. The same correspondingly holds true for the coolant collected in the coolant collector chamber after flowing through the cooling channels. Since the coolant distributor chamber and/or respectively coolant collector chamber are/is thus arranged directly adjacent to the stator windings to be cooled, an effective thermal coupling of the coolant distributor chamber and/or respectively coolant collector chamber to the stator windings to be cooled is achieved in this way.
An electrical machine according to the invention, particularly for a vehicle, comprises a rotor, which is rotatable about a rotation axis. The rotation axis defines an axial direction of the electrical machine. The machine furthermore comprises a stator having stator windings. The machine furthermore comprises a coolant distributor chamber and a coolant collector chamber arranged axially at a distance therefrom. A coolant can flow through the coolant distributor chamber for the purpose of cooling the waste heat generated by the stator winding and said coolant distributor chamber communicates fluidically with the coolant collector chamber by means of at least one cooling channel. Preferably, at least two, particularly preferably a plurality of such cooling channels are provided. At least one stator winding is embedded at least in sections, preferably completely, into a plastic composition composed of an electrically insulating plastic for the purpose of thermal coupling to the coolant. In this case, the coolant distributor chamber and/or the coolant collector chamber are/is arranged in the region of a first and/or second axial end section of at least one stator winding. Preferably, the coolant distributor chamber and/or the coolant collector chamber are/is arranged in an axial extension of the first and/or second end section. According to the invention, the coolant distributor chamber and/or the coolant collector chamber are/is embodied at least partly in the plastic composition and thus at least partly delimited by the latter for the purpose of thermal coupling to the at least one stator winding.
In accordance with one preferred embodiment, the coolant distributor chamber and/or the coolant collector chamber in a longitudinal section along the rotation axis surround(s) the first and/or second axial end section of the at least one stator winding in a U-shaped or C-shaped manner. In this way, the end sections particularly subjected to thermal loading are virtually surrounded by the coolant distributor chamber and/or by the coolant collector chamber, with the result that a particularly good thermal coupling of the coolant to the end sections of the respective stator winding can be effected.
Particularly preferably, the coolant distributor chamber and/or the coolant collector chamber in the longitudinal section along the axial direction therefore have/has a U-shaped or C-shaped geometric shaping.
In one advantageous development, the coolant distributor chamber and/or the coolant collector chamber are/is also arranged radially on the outside of the first and/or second end section of the at least one stator winding.
Expediently, the coolant distributor chamber and/or the coolant collector chamber can have a ring-shaped geometric shaping in a cross section perpendicular to the rotation axis of the rotor. This allows a plurality of cooling channels to be arranged at a distance from one another along the circumferential direction along the stator.
Particularly preferably, the at least one plastic composition at least partly delimits the coolant distributor chamber and/or the coolant collector chamber. The provision of a separate housing can thus be obviated.
In accordance with a further preferred embodiment, the coolant distributor chamber and/or the coolant collector chamber are/is embodied by a cavity provided at least partly, preferably completely, in the plastic composition. The provision of a separate enclosure or a housing for delimiting the coolant distributor chamber and/or coolant collector chamber can thus be obviated. This is associated with not inconsiderable cost advantages.
In accordance with one preferred embodiment, the at least one cooling channel is also embedded into the at least one plastic composition composed of the electrically insulating plastic. This ensures a good thermal coupling of the coolant flowing through the cooling channel to the relevant stator windings.
In accordance with another preferred embodiment, the stator has stator teeth extending along the axial direction and arranged at a distance from one another along a circumferential direction, said stator teeth carrying the stator windings. In this embodiment, the plastic composition together with the at least one cooling channel and the at least one stator winding is arranged in an interspace embodied between two stator teeth that are adjacent in the circumferential direction. This measure ensures a particularly good heat transfer between the stator windings and the cooling channel since the cooling channel is arranged in the interspace in direct proximity to the stator windings to be cooled. Furthermore, said interspace between the stator teeth can be used during the production of the plastic composition in the manner of a mold into which the plastic of the plastic composition is injected. This simplifies the production of the plastic composition since the provision of a separate mold can be obviated.
A further preferred embodiment proposes subdividing the interspace into a first and a second subspace. In this configuration, the at least one stator winding is arranged in the first subspace. The at least one cooling channel is arranged in the second subspace. A positioning aid is embodied between the two subspaces, by means of which positioning aid the at least one cooling channel is positionable in the second subspace. This measure allows precise and stable positioning of the cooling channel—which is typically a tube body or a flat tube—, particularly if the latter together with the stator windings in the interspace between the two stator teeth is encapsulated by injection molding with the plastic that produces the plastic composition.
In one advantageous development of this configuration, the positioning aid comprises two projections embodied at two stator teeth which are adjacent in the circumferential direction. The two projections face one another in the circumferential direction of the rotor and project into the interspace for the purpose of positioning the cooling channel. This configuration allows a particularly accurate alignment of the cooling channel in the interspace before encapsulation by injection molding with the plastic of the plastic composition.
In accordance with one preferred embodiment, the plastic composition arranged in the interspace consists of a single plastic material. In this embodiment, an additional electrical insulation composed of an electrically insulating material is arranged in the interspace, preferably between the stator winding or plastic composition and the stator tooth. Since, in this embodiment, only a single plastic material has to be introduced into the interspaces, the production of the plastic composition composed of said plastic can be effected in a single injection-molding step. The production of the plastic composition therefore turns out to be particularly simple, which is associated with cost advantages.
Expediently, the electrically insulating plastic of the plastic composition comprises a thermosetting plastic or is a thermosetting plastic. Alternatively, the electrically insulating plastic of the plastic composition can comprise a thermoplastic or be a thermoplastic. A combination of a thermosetting plastic and a thermoplastic is also conceivable in a further variant.
Expediently, the plastic composition substantially completely fills the interspace. The formation of undesired interspaces, for instance in the manner of air gaps, which would result in an undesired reduction of the heat transfer, is avoided in this way.
In accordance with one preferred embodiment, the at least one plastic composition projects axially, preferably on both sides, from the interspace. The plastic composition can thus be used for embodying the coolant distributor chamber and/or coolant collector chamber.
In accordance with another preferred embodiment, the at least one cooling channel is arranged radially outside and/or radially within the respective stator winding in the interspace. This enables a space-saving arrangement of the cooling channel near the stator windings to be cooled, with the result that the electrical machine requires only little structural space for the cooling of the stator windings.
One preferred configuration proposes embodying the at least one cooling channel as a tube body surrounding a tube body interior. In this variant, at least one separating element is shaped at the tube body and subdivides the tube body interior into at least two partial cooling channels which are fluidically separated from one another. The tube body can be reinforced by means of said separating elements, and so its mechanical strength increases.
Expediently, the tube body can be embodied as a flat tube having two broad sides and two narrow sides.
One advantageous development proposes embodying the tube body as a flat tube which extends along the axial direction and has two broad sides and two narrow sides in a cross section perpendicular to the axial direction. Expediently, in the cross section perpendicular to the axial direction at least one broad side of the flat tube extends perpendicular to the radial direction. In this case, a length of the two broad sides can preferably be at least four times, preferably at least ten times, a length of the two narrow sides.
Particularly preferably, the at least one cooling channel is arranged completely in the plastic composition composed of the plastic.
In accordance with a further preferred embodiment, the stator in a cross section perpendicular to the axial direction is embodied in a ring-shaped fashion and has stator teeth extending along the axial direction and arranged at a distance from one another along a circumferential direction of the stator, said stator teeth carrying the stator windings. In this embodiment, the plastic composition together with the at least one cooling channel and the at least one stator winding is arranged in an interspace embodied between two stator teeth that are adjacent in the circumferential direction. This measure ensures a particularly effective heat transfer between the stator windings and the cooling channel since the cooling channel arranged in the interspace is situated in direct proximity to the stator windings to be cooled. Furthermore, the interspace between the stator teeth can be used during the production of the plastic composition in a manner of a mold into which the plastic of the plastic composition is injected. This simplifies the production of the plastic composition since the provision of a separate mold can be obviated.
In accordance with a further preferred embodiment, the at least one cooling channel is formed by at least one perforation, preferably by a plurality of perforations, which is/are provided in the plastic composition and through which the coolant can flow. Particularly preferably, a plurality of such perforations are provided. The provision of a separate tube body or the like for delimiting the cooling channel is obviated in this variant. This is associated with reduced production costs. Said perforation can be realized in the form of a through hole introduced into the plastic composition by means of a suitable drilling tool. The provision of a separate tube body or the like for delimiting the cooling channel is obviated in this variant. This is associated with reduced production costs.
Expediently, at least one perforation in a cross section perpendicular to the axial direction can have the geometry of a rectangle having two broad sides and two narrow sides. In this way, the advantageous geometry of a flat tube is imparted to the perforation, said geometry in turn allowing a structural-space-saving arrangement of the cooling channel in direct proximity to the stator winding(s) to be cooled.
In accordance with a further preferred embodiment, at least one cooling channel is arranged in the stator body and is formed by at least one perforation through which the coolant can flow. Said perforation can be realized in the form of a through hole introduced into the stator body by means of a suitable drilling tool in the course of the production of the electrical machine. The provision of a separate tube body or the like for delimiting the cooling channel is obviated in this variant. This is associated with reduced production costs.
In a further preferred embodiment, the perforation forming the cooling channel is embodied as open toward the interspace. Moreover, said perforation is closed in a fluid-tight fashion by the plastic composition arranged in the interspace. In this variant, the perforations are able to be produced particularly simply, which is associated with cost advantages during production.
Expediently, the at least one cooling channel is arranged in the stator body in the region between two adjacent stator teeth with respect to the circumferential direction. This makes it possible to arrange the cooling channel near the stator windings to be cooled, which improves the heat transfer from the stator windings to the cooling channel.
In accordance with another preferred embodiment, at least one cooling channel is provided in the plastic composition and at least one further cooling channel is provided in the stator body. This variant requires particularly little structural space since both the stator body and the plastic composition are used for accommodating the cooling channel.
In accordance with another preferred embodiment, the stator is arranged along the axial direction between a first and a second end shield, which lie opposite one another along the axial direction. In this embodiment, a part of the coolant distributor chamber is arranged in the first end shield. Alternatively or additionally, a part of the coolant collector chamber is arranged in the second coolant collector chamber.
In accordance with another preferred embodiment, a coolant feed is embodied in the first end shield and fluidically connects the coolant distributor chamber to a coolant inlet provided on the outside, preferably on the end side, of the first end shield. Furthermore, a coolant discharge is embodied in the second end shield and fluidically connects the coolant collector chamber to a coolant outlet provided on the outside, preferably on the end side, of the second end shield. Particularly preferably, the coolant feed can be thermally connected to a first shaft bearing for the rotatable mounting of the stator, said first shaft bearing being provided in the first end shield. In an analogous manner, the coolant discharge can be thermally connected to a second shaft bearing for the rotatable mounting of the stator, said second shaft bearing being provided in the second end shield.
Particularly preferably, the plastic composition is an injection-molded composition composed of an electrically insulating plastic. The application of an injection-molding method simplifies and accelerates the production of the plastic composition. This results in cost advantages during the production of the electrical machine.
Particularly preferably, the entire plastic composition, that is to say in particular the plastic composition arranged in the interspaces between the stator teeth and the plastic composition delimiting the coolant distributor chamber and the coolant collector chamber, is embodied in integral fashion. This measure simplifies the production of the electrical machine, which is associated with cost advantages.
In one advantageous development, the stator comprises a, preferably ring-shaped, stator body, from which the stator teeth protrude. In this development, the plastic composition composed of the electrically insulating plastic is arranged on an outer circumferential side of the stator body and preferably forms a plastic coating on said outer circumferential side. The stator can thus be electrically insulated from the surroundings. The provision of a separate housing for accommodating the stator body can thus be obviated. A coating of at least one or both end sides of the stator body with the plastic composition is also conceivable in an optional variant. In a further variant, the plastic composition can envelop, preferably completely, the stator body.
Particularly preferably, the coolant distributor chamber and/or the coolant collector chamber axially adjoin(s) the at least one stator winding. Since the coolant distributor chamber and/or coolant collector chamber are/is thus arranged directly adjacent to the stator windings to be cooled with respect to the axial direction, an effective thermal coupling of the coolant distributor chamber and/or coolant collector chamber to the stator windings to be cooled is achieved in this way.
In accordance with a further preferred embodiment, the coolant collector chamber and/or the coolant distributor chamber adjoin(s) the at least one stator winding radially on the outside and/or radially on the inside and axially at the end face, with preference adjoin(s) the first and/or respectively second axial end section of said at least one stator winding.
In accordance with one preferred embodiment, the plastic composition at least partly surrounds at least one winding section of at least one stator winding that projects axially from the interspace of the stator body, and in this case partly delimits the coolant distributor chamber and/or the coolant collector chamber, such that said winding section of the stator winding is electrically insulated from the coolant. An undesired electrical short circuit of the coolant with the stator winding during operation of the electrical machine is prevented in this way.
In accordance with one advantageous development, the coolant distributor chamber communicates fluidically with the coolant collector chamber by means of a plurality of cooling channels.
Expediently, the plurality of cooling channels extend at a distance from one another along the axial direction. This measure ensures that all axial sections of the stator windings are cooled.
Preferably, the cooling channels are arranged at a distance from one another along a circumferential direction of the stator. This measure ensures that along the circumferential direction all stator windings are cooled.
In accordance with another preferred embodiment, the coolant distributor chamber and/or coolant collector chamber are/is arranged exclusively in an axial extension of the stator body adjacent thereto. Preferably, in this embodiment, the coolant distributor chamber and/or the coolant collector chamber do[es] not project beyond the stator body or stator along a radial direction thereof. This embodiment requires only very little structural space in a radial direction.
Particularly preferably, at least one stator winding is embodied such that it is electrically insulated from the coolant and from the stator body at least in the region within the respective interspace during operation of the electrical machine. Particularly preferably, this applies to all the stator windings of the electrical machine. An undesired electrical short circuit of the stator winding with the stator body or—during operation of the electrical machine—with the coolant is prevented in this way.
Particularly expediently, this electrical insulation of the at least one stator winding from the stator body, preferably also from the stator teeth delimiting the interspace, is formed completely by the plastic composition and/or by the additional insulation—already mentioned above. The provision of a further electrical insulation can be obviated in this way.
In accordance with another preferred embodiment, the additional electrical insulation extends within the interspace over the entire length of the interspace as measured along the axial direction, such that it insulates the stator winding from the stator body and from the stator teeth delimiting the interspace.
In accordance with one advantageous development, the additional electrical insulation encloses the stator winding within the interspace over at least the entire length of the interspace along the circumference thereof.
In one particularly preferred embodiment, the at least one stator winding is also electrically insulated from the cooling channel embodied as a tube body. In this case, the electrical insulation is formed by the plastic composition and/or the additional electrical insulation.
Particularly preferably, the stator windings can be part of a distributed winding.
The invention furthermore relates to a vehicle, in particular a motor vehicle, comprising an electrical machine presented above. The above-explained advantages of the electrical machine are therefore also applicable to the vehicle according to the invention.
Further important features and advantages of the invention are evident from the dependent claims, from the drawings and from the associated description of the figures with reference to the drawings.
It goes without saying that the features mentioned above and those yet to be explained below are usable not only in the combination respectively indicated, but also in other combinations or by themselves, without departing from the scope of the present invention.
Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in greater detail in the following description.
In the figures, schematically in each case:
The electrical machine 1 comprises a rotor 3, which is merely illustrated roughly schematically in
As can be discerned from
The stator 2 additionally comprises, in a known manner, a plurality of stator windings 6, which are electrically energizable for the purpose of generating a magnetic field. Magnetic interaction between the magnetic field generated by the magnets of the rotor 3 and the magnetic field generated by the stator windings 6 causes the rotor 3 to rotate.
The cross section in
During operation of the machine 1, the electrically energized stator windings 6 generate waste heat which has to be dissipated from the machine 1 in order to prevent overheating and associated damage or even destruction of the machine 1. Therefore, the stator windings 6 are cooled with the aid of a coolant K which is passed through the stator 2 and absorbs the waste heat generated by the stator windings 6 by means of heat transfer.
In order to pass the coolant K through the stator 2, the machine 1 comprises a coolant distributor chamber 4, into which a coolant K can be introduced via a coolant inlet 33. A coolant collector chamber 5 is arranged at a distance from the coolant distributor chamber 4 along the axial direction A. The coolant distributor chamber 4 communicates fluidically with the coolant collector chamber 5 by means of a plurality of cooling channels 10, only a single one of which is discernible in the illustration in
As revealed by the illustration in
Attention shall now be directed to the illustration in
As further revealed by the detailed illustration in
As demonstrated by the detailed illustration in
In the example in
In the text that follows, reference is made once again to
In this way, even in the region of the axial end sections 14a, 14b of the relevant stator winding 6, said end sections usually being particularly subjected to thermal loading, it is possible to produce an effective heat transfer to the coolant K present in the coolant distributor chamber 4 and/or coolant collector chamber 5. This measure allows particularly effective cooling of the two axial end sections 14a, 14b of the stator winding 6.
Furthermore, in accordance with
The coolant distributor chamber 4 and the coolant collector chamber 5 are in each case partly formed by a cavity 41a, 41b provided in the plastic composition 11. The first cavity 41a is supplemented by a cavity 42a embodied in the first end shield 25a to form the coolant distributor chamber 4. Correspondingly, the second cavity 41b is supplemented by a cavity 42b embodied in the second end shield 25b to form the coolant collector chamber 5.
Furthermore, a coolant feed 35 can be embodied in the first end shield 25a and fluidically connects the coolant distributor chamber 4 to a coolant inlet 33 provided on the outside, in particular on the circumferential side as illustrated in
In accordance with
In accordance with
In order to produce an electrical machine 1 in accordance with
Attention shall now be directed to the illustration in
It goes without saying that the stator winding 6 arranged in the interspace 9 in accordance with
In the example in
As further revealed by the detailed illustration in
In the example in
The variants in accordance with
The plastic composition 11 can also surround that winding section of the stator winding 6 which projects axially from the interspace 9 of the stator body, and in so doing partly delimit the coolant distributor chamber 4 and/or the coolant collector chamber 5, such that the relevant stator winding 6 or the relevant winding section of the stator winding 6 is electrically insulated from the coolant when the latter is passed through the relevant cooling channel 10 during operation of the machine 1.
Expediently, the coolant distributor chamber 4 and the coolant collector chamber 5 are arranged in an axial extension of the stator body 7 adjacent to the latter. Preferably, the coolant distributor chamber 4 and/or the coolant collector chamber 5 do(es) not project beyond the stator body 7 or stator 2 along the radial direction R thereof.
The stator winding 6 is embodied in each case such that it is electrically insulated from the coolant K and from the stator body 7 of the stator 2 at least in the region within the respective interspace 9 during operation of the electrical machine 1. An undesired electrical short circuit of the stator winding 6 with the stator body 7—during operation of the electrical machine 1—with the coolant K is prevented in this way. Expediently, such an electrical insulation of the stator winding 6 vis-à-vis the stator body 7—preferably also vis-à-vis the stator teeth 8 delimiting the interspace 9—is formed completely by the plastic composition 11 and/or by the additional electrical insulation 15—already mentioned above.
Expediently, the additional electrical insulation 15 extends within the interspace 9 over the entire length of the interspace 9 as measured along the axial direction A, such that it insulates the stator winding 6 from the stator body 7 and/or from the stator teeth 8. The additional electrical insulation 15 likewise expediently encloses the stator winding 6 within the interspace 9 over at least the entire length of the interspace 9 along the circumferential boundary thereof. Expediently, the stator winding 6 is also electrically insulated from the cooling channel embodied as a tube body 16. In this case, the electrical insulation is formed by the plastic composition and, alternatively or additionally, the additional electrical insulation 15.
Number | Date | Country | Kind |
---|---|---|---|
10 2017 208 564.9 | May 2017 | DE | national |
This application claims priority to International Patent Application No. PCT/EP2018/063138 filed May 18, 2018, which also claims priority to German Patent Application DE 10 2017 208 564.9 filed May 19, 2017, each of which is hereby incorporated by reference in its entirety.
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/EP2018/063138 | 5/18/2018 | WO | 00 |