The invention relates to an electrical machine, particularly for a vehicle, and to a vehicle with such a machine.
An electrical machine of this type can in general be an electric motor or a generator. The electrical machine can be in the form of an external rotor or an internal rotor.
A machine of the type in question is known, for example, from U.S. Pat. No. 5,214,325. It comprises a housing which surrounds an interior space and which has a casing encircling in a circumferential direction of the housing and radially bounding the interior space, a rear side wall axially bounding the interior space axially on one side and a front side wall axially bounding the interior space axially on the other side. A stator of the machine is fixedly connected to the casing. A rotor of the machine is arranged in the stator, with a rotor shaft of the rotor being mounted rotatably on the front side wall via a front shaft bearing.
The stator of a conventional electrical machine typically comprises stator windings which are electrically energized during the operation of the machine. In the process, heat arises 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 said machines 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 can be dissipated from the stator by transmission of heat from the stator windings to the coolant.
It has proven disadvantageous here that efficient transfer of heat from the stator to the coolant flowing through the respective cooling channel is associated only with a considerable structural outlay. However, this has a disadvantageous effect on the production costs of the electrical machine.
It is therefore an object of the present invention to provide an improved embodiment for an electrical machine, in which said disadvantage is substantially or even completely eliminated. In particular, the intention is to provide an improved embodiment for an electrical machine that is distinguished by improved cooling of the stator windings of the stator.
This object is achieved by the subject matter of the independent patent claims. Preferred embodiments are the subject matter of the dependent patent claims.
Accordingly, the basic concept of the invention is to embed the stator windings of an electrical machine together with a cooling channel through which a coolant flows and which is provided for cooling the stator windings into a plastics compound consisting of an electrically insulating plastic. The plastic can therefore act firstly as a heat-transmitting medium for transmitting heat from the stator windings to the coolant and secondly as an electrical insulator for the stator windings. In particular, particularly good transfer of heat between the stator windings and the coolant guided through the cooling channel is thereby produced. This is true in particular if use is made of a plastic which has high thermal conductivity. Particularly what are referred to as thermosetting plastics are suitable for this purpose. Use of an electrically insulating plastic simultaneously ensures that the stator windings to be cooled are not undesirably electrically short-circuited by the plastic.
The direct thermal coupling of the cooling channel with the coolant to the stator windings to be cooled, with the aid of the embedding essential to the invention of said two components in a plastics compound leads to particularly effective cooling of the stator windings in comparison to conventional cooling devices. Even when a high level of waste heat is produced in the stator, as occurs, for example, in a high-load mode of the electrical machine, it can therefore be ensured that the waste heat which arises can be dissipated from the stator. Damage or even destruction of the electrical machine due to overheating of the stator can therefore be avoided. The plastics compound essential to the invention can preferably be produced by means of injection molding with the stator windings to be cooled and the cooling channel being insert molded with the plastic in order to form the plastics compound. The embedding of the stator windings and of the cooling channel in the plastics compound therefore turns out to be very simple. Considerable cost advantages thereby arise in the production of the electrical machine according to the invention.
An electrical machine according to the invention, in particular for a vehicle, comprises a rotor which is rotatable about an axis of rotation. The axis of rotation defines an axial direction of the electrical machine. In addition, the machine comprises a stator which has a plurality of stator windings. The machine furthermore comprises a coolant distributor chamber and a coolant collector chamber arranged axially at a distance from the latter. The coolant distributor chamber fluidically communicates here with the coolant collector chamber by means of at least one cooling channel through which a coolant can flow. A plurality of such cooling channels are preferably provided between the coolant distributor chamber and the coolant collector chamber. According to the invention, for the thermal coupling to the coolant, the at least one cooling channel and the at least one stator winding are embedded at least in sections in a plastics compound consisting of an electrically insulating plastic.
According to a preferred embodiment, for the thermal coupling to the stator windings, the coolant distributor chamber and/or the coolant collector chamber are at least partially arranged in the at least one plastics compound. This permits a particularly good transfer of heat between the coolant distributor chamber or coolant collector chamber and the stator windings, and therefore the coolant distributor chamber or the coolant collector chamber can also be used for directly absorbing heat from the stator windings.
According to another preferred embodiment, the stator has stator teeth which extend along the axial direction, are arranged at a distance from one another along a circumferential direction and carry the stator windings. In this embodiment, the plastics compound is arranged with the at least one cooling channel and with the at least one stator winding in an intermediate space which is formed between two adjacent stator teeth in the circumferential direction. This measure ensures particularly good transfer of heat between the stator windings and the cooling channel since the cooling channel is arranged in the intermediate space in the immediate vicinity of the stator windings to be cooled. Furthermore, during the production of the plastics compound, said intermediate space between the stator teeth can be used in the manner of a casting mold into which the plastic of the plastics compound is injected. This simplifies the production of the plastics compound since the provision of a separate casting mold can be omitted.
A further preferred refinement proposes dividing the intermediate space into a first and a second partial space. In this refinement, the at least one stator winding is arranged in the first partial space. The at least one cooling channel is arranged in the second partial space. A positioning aid is formed between the two partial spaces, by means of which positioning aid the at least one cooling channel can be positioned in the second partial space. This measure permits precise and stable positioning of the cooling channel—which is typically a tubular body or a flat tube—if said cooling channel is insert molded together with the stator windings in the intermediate space between the two stator teeth with the plastic producing the plastics compound.
In an advantageous development of this refinement, the positioning aid comprises two projections which are formed on two adjacent stator teeth in the circumferential direction. The two projections face each other in the circumferential direction of the rotor and project into the intermediate space in order to position the cooling channel. This refinement permits a particularly precise alignment of the cooling channel in the intermediate space prior to the insert molding with the plastic of the plastics compound.
The plastics compound expediently projects axially, preferably on both sides, out of the respective intermediate space. The plastics compound can therefore also be used for partially bounding the coolant distributor chamber or the coolant collector chamber. In particular, the required removal during the production of the machine of that part of the plastics compound which projects from the intermediate space can be omitted, which is associated with cost advantages during the production of the machine.
A further advantageous refinement therefore proposes that the at least one plastics compound at least partially bounds the coolant distributor chamber and/or the coolant collector chamber. The provision of a separate boundary for the coolant distributor chamber or the coolant collector chamber, for example in the form of a housing, can therefore be omitted.
According to a preferred embodiment, a plastics compound arranged in the intermediate space is composed of a single plastics material. In this embodiment, additional electrical insulation consisting of an electrically insulating material is arranged in the intermediate space, preferably between the stator winding or plastics compound and the stator tooth. Since, in this embodiment, only a single plastics material has to be introduced in the intermediate spaces, the production of the plastics compound from said plastic can take place in a single injection molding step. The production of the plastics compound therefore turns out to be particularly simple, which is associated with cost advantages.
The plastics compound expediently substantially completely fills the intermediate space. The formation of undesirable intermediate spaces, for example in the manner of air gaps, which would lead to an undesirable reduction in the transfer of heat, is thereby avoided.
The electrically insulating plastic of the plastics compound expediently comprises a thermosetting plastic or is a thermosetting plastic. Alternatively, the electrically insulating plastic of the plastics compound can comprise a thermoplastic or can be a thermoplastic. In a further variant, a combination of a thermosetting plastic and a thermoplastic is also conceivable.
Expediently, in each case at least one cooling channel and the plastics compound can be provided in at least one, preferably in each, intermediate space between two respectively adjacent stator teeth in the circumferential direction. This ensures that operationally generated waste heat can be dissipated from all of the stator windings present.
According to another preferred embodiment, the at least one cooling channel is arranged radially outside and/or radially within the respective stator winding in the intermediate space. This permits a space-saving arrangement of the cooling channel close to the stator windings to be cooled, and therefore the electrical machine requires only little construction space for the cooling of the stator windings.
A preferred refinement proposes designing the at least one cooling channel as a tubular body which surrounds a tubular body interior space. In this variant, at least one separating element which divides the tubular body interior space into at least two partial cooling channels separated fluidically from one another is formed on the tubular body. The tubular body can be stiffened by means of said separating elements, and therefore the mechanical strength of the tubular body is increased.
An advantageous development proposes designing the tubular body as a flat tube which extends along the axial direction and, in a cross section perpendicular to the axial direction, has two wide sides and two narrow sides. Expediently, in the cross section perpendicular to the axial direction, at least one wide side of the flat tube extends substantially perpendicularly to the radial direction. A length of the two wide sides can preferably be at least four times, preferably at least ten times, a length of the two narrow sides.
According to a further preferred embodiment, the coolant distributor chamber and/or the coolant collector chamber are/is formed by a cavity present at least partially, preferably completely, in the plastics compound. The provision of a separate covering or of a housing for bounding the coolant distributor chamber or coolant collector chamber can therefore be omitted. Not inconsiderable cost advantages are associated therewith.
The plastics compound is particularly preferably an injection molding compound consisting of an electrically insulating plastic. The use of an injection molding process simplifies and accelerates the production of the plastics compound. This leads to cost advantages in the production of the electrical machine.
In an advantageous development, the stator comprises a, preferably annular, stator body from which the stator teeth protrude. In this development, the plastics compound consisting of the electrically insulating plastic is arranged on an outer circumferential side of the stator body and preferably forms a plastics coating on said outer circumferential side. The stator can therefore be electrically insulated from the surroundings. The provision of a separate housing for receiving the stator body can therefore be omitted. In an optional variant, coating of at least one or both end sides of the stator body with the plastics compound is also conceivable. In a further variant, the plastics compound can encase the stator body, preferably completely.
According to a preferred embodiment, the plastics compound at least partially surrounds at least one winding portion of at least one stator winding, said winding portion projecting axially out of the intermediate space of the stator body, and partially bounds the coolant distributor chamber and/or the coolant collector chamber in the process such that said winding portion of the stator winding is electrically insulated in relation to the coolant. An undesirable electrical short circuit of the coolant with the stator winding during the operation of the electrical machine is thereby prevented.
According to an advantageous development, the coolant distributor chamber fluidically communicates with the coolant collector chamber by means of a plurality of cooling channels.
The plurality of cooling channels expediently extends, in each case at a distance from one another, along the axial direction. This measure ensures that all of the axial portions of the stator windings are cooled.
The cooling channels are preferably arranged at a distance from one another along a circumferential direction of the stator. This measure ensures that all of the stator windings are cooled along the circumferential direction.
According to another preferred embodiment, the coolant distributor chamber and/or the coolant collector chamber are/is arranged adjacent to the stator body exclusively in an axial extension thereof. Preferably, in this embodiment, the coolant distributor chamber or the coolant collector chamber does not project beyond the stator body or stator in a radial direction thereof. This embodiment requires only very little construction space in the radial direction.
Particularly preferably, at least one stator winding is designed in such a manner that it is insulated electrically from the coolant and from the stator body at least in the region within the respective intermediate space during operation of the electrical machine. This is particularly preferably true of all of the stator windings of the electrical machine. An undesirable electrical short circuit of the stator winding with the stator body—during the operation of the electrical machine—with the coolant is thereby prevented.
Particularly expediently, said electrical insulation of the at least one stator winding from the stator body, preferably also from the stator teeth bounding the intermediate space, is formed completely by the plastics compound and/or by the additional electrical insulation already mentioned above. The provision of a further electrical insulator can thereby be omitted.
According to another preferred embodiment, the additional electrical insulation within the intermediate space extends over the entire length of the intermediate space, as measured along the axial direction, such that said insulation insulates the stator winding from the stator body and from the stator teeth bounding the respective intermediate space.
According to an advantageous development, the additional electrical insulation surrounds the stator winding within the intermediate space over at least the entire length of the intermediate space along the circumference thereof.
In a particularly preferred embodiment, the at least one stator winding is also electrically insulated from the cooling channel, which is in the form of a tubular body. The electrical insulation is formed here by the plastics compound and/or the additional insulation.
The stator windings can particularly preferably 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 therefore also apply to the vehicle according to the invention.
Further important features and advantages of the invention emerge 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 which have yet to be explained below can be used not only in the respectively stated combination, but also in different combinations or on their own without departing from the scope of the present invention.
Preferred exemplary embodiments of the invention are illustrated in the drawings and will be explained in more detail in the description below.
In the drawings, in each case schematically:
The electrical machine 1 comprises a rotor 3, illustrated only roughly schematically in
As
In addition, the stator 2 comprises in a known manner a plurality of stator windings 6 which can be electrically energized in order to generate a magnetic field. The rotor 3 is set into rotation by magnetic interaction of the magnetic field generated by the magnets of the rotor 3 with the magnetic field generated by the stator windings 6. The stator windings 6 can be part of a distributed winding.
It is gathered from the cross section of
During the 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. The stator windings 6 are therefore cooled with the aid of a coolant K which is guided through the stator 2 and which, by transmission of heat, absorbs waste heat generated by the stator windings 6.
In order to guide 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 along the axial direction A at a distance from the coolant distributor chamber 4. The coolant distributor chamber 4 communicates fluidically with the coolant collector chamber 5 by means of a plurality of cooling channels 10, of which only a single one can be seen in the illustration of
As can be seen in the illustrations of
Attention will now be turned to the illustration of
As the detailed illustration of
As the detailed illustration of
In the example of
In order to produce an electrical machine 1 according to
According to
Reference is again made to
Furthermore, according to
As
The first cavity 41a is complemented here by a cavity 42a, formed in the first bearing plate 25a, to form the coolant distributor chamber 4. In a corresponding manner, the second cavity 41b is complemented by a cavity 42b, formed in the second end plate 25b, to form the coolant collector chamber 5. In the variant embodiment explained above, the plastics compound 11 therefore at least partially bounds the coolant distributor chamber 4 and the coolant collector chamber 5.
The first bearing plate 25a can furthermore contain a coolant feed 35 which fluidically connects the coolant distributor chamber 4 to a coolant inlet 33 provided on the outside, in particular, as illustrated in
According to
The stator windings 6 are guided outward from the stator 2 with an electrical connection 50 through a leadthrough 39 provided in the second end plate 25b, and therefore said stator windings can be electrically energized from the outside.
The leadthrough 39 is arranged radially between the coolant distributor chamber 4 or the coolant collector chamber 5 and the axis of rotation D.
In the example of
In the variant according to
A development of
The plastics compound 11 can also surround the winding portion of the stator winding 6 that projects axially out of the intermediate space 9 of the stator body, and can partially bound the coolant distributor chamber 4 or the coolant collector chamber 5 in the process such that the relevant stator windings 6 or the relevant winding portion of the stator winding 6 is insulated electrically in relation to the coolant when the latter is guided through the relevant cooling channel 10 during the operation of the machine 1.
The coolant distributor chamber 4 and the coolant collector chamber 5 are expediently arranged adjacent to the stator body 7 in an axial extension thereof. The coolant distributor chamber 4 or the coolant collector chamber 5 preferably does not project beyond the stator body 7 or stator 2 along the radial direction R thereof.
The stator winding 6 is in each case designed in such a manner 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 intermediate space 9 during the operation of the electrical machine 1. An undesirable electrical short circuit of the stator winding 6 with the stator body 7—during the operation of the electrical machine 1—with the coolant K is thereby prevented. Such electrical insulation of the stator winding 6 in relation to the stator body 7—preferably also in relation to the stator teeth 8 bounding the intermediate space 9—is expediently completely formed by the plastic compound 11 and/or by the additional electrical insulation 15 already mentioned above.
The additional electrical insulation 15 expediently extends within the intermediate space 9 over the entire length of the intermediate space 9, as measured along the axial direction A, such that the electrical insulation insulates the stator winding 6 from the stator body 7 and/or from the stator teeth 8. The additional electrical insulation 15 likewise expediently surrounds the stator winding 6 within the intermediate space 9 over at least the entire length of the intermediate space 9 along the circumferential boundary thereof. The stator winding 6 is expediently also electrically insulated from the cooling channel, which is in the form of a tubular body 16. The electrical insulation is formed here by the plastics compound and, alternatively or additionally, by the additional electrical insulation 15.
Number | Date | Country | Kind |
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10 2017 208 546.0 | May 2017 | DE | national |
This application claim priority to International Patent Application No. PCT/EP2018/063165 filed May 18, 2018, which also claims priority to German Patent Application DE 10 2017 208 546.0 filed May 19, 2017, each of which is hereby incorporated by reference in its entirety.
Filing Document | Filing Date | Country | Kind |
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PCT/EP2018/063165 | 5/18/2018 | WO | 00 |