DE102019135140A1 - Electric machine stator, related manufacturing process, electric machine, and vehicle - Google Patents

Abstract

Stator (1) for an electrical machine (100), comprising
- A stator core (2) with stator slots (3) which are arranged distributed in a circumferential direction with respect to a central axis (4) of the stator core (2), and
- a hairpin winding (5); wherein the hairpin winding (5) comprises several pairs (7) of shaped conductors (6a, 6b) through which a cooling fluid can flow and which extend through two different stator slots (3), the shaped conductors (6a, 6b) of a respective pair (7) are electrically conductively connected to one end face of the stator (1) by a connecting device (8) which is fastened to the shaped conductors (6a, 6b) and through which the cooling fluid cannot flow.

Description

The present invention relates to a stator for an electrical machine, comprising a stator core with stator slots, which are arranged distributed in a circumferential direction with respect to a central axis of the stator core, and a hairpin winding.

In addition, the invention relates to a method for producing a stator for an electrical machine, an electrical machine and a vehicle.

Stators with a hairpin winding have become the focus of industrial development efforts, particularly in the field of electric drives for vehicles. Compared to distributed windings, they allow largely automated production, because there is no need to draw in a winding made of thin wires. When operating an electrical machine having such a stator, heat losses occur which are essentially proportional to the current flowing through the hairpin winding. If these currents become too high, a thermal fault can occur on the stator, in particular on the hairpin winding. It has already been proposed to cool such stators by a cooling fluid, for example oil, in order to achieve a high degree of utilization of the electrical machine.

The document DE 10 2017 204 472 A1 discloses a stator for an electrical machine having a central axis, the stator comprising a stator winding formed by electrically connecting a plurality of prefabricated hairpin-shaped conductor elements and a stator yoke having a plurality of slots. The stator winding has a plurality of interconnected conductor segments, each with an axially inner inner section and two axially outer outer sections, the inner sections being embedded in the slots of the stator yoke and channels for the flow of coolant being formed in some of the slots in the axial direction . Each hairpin-shaped conductor element comprises two inner sections which are connected to one another by an outer section bent in a U-shape. The hairpins are formed from waveguides, the hollow open end of the hairpin being used to feed coolant into the interior of the conductor elements.

To build such a stator, hollow shaped conductors are bent to form a U-pin. This requires at least the formation of an acute-angled bend of the shaped conductor, which locally reduces the inner diameter of the conductor and thus locally increases a volume flow density of the cooling fluid. If it is desired to guide the cooling fluid out of the shaped conductor at the end face of the stator having the bend, complex bores must be made in the shaped conductor, which must be positioned exactly in order to correctly reach the cavity. This is extremely time-consuming.

The invention is therefore based on the object of specifying an improved possibility, particularly advantageous in terms of fluid mechanics and / or which can be implemented with little effort, for cooling a stator having a hairpin winding.

This object is achieved according to the invention in a stator of the type mentioned at the outset in that the hairpin winding comprises several pairs of shaped conductors through which a cooling fluid can flow and which extend through two different stator slots, the shaped conductors of a respective pair being connected to one end face of the stator by an The connecting device attached to the shaped conductors, through which the cooling fluid cannot flow, are connected in an electrically conductive manner.

The invention is based on the idea of realizing a U-shaped structure with regard to the flow of electrical current through the pair of shaped conductors by being connected in an electrically conductive manner by a connecting device. The cooling fluid can thus flow through a respective shaped conductor and can easily be introduced into or out of the respective shaped conductor of the pair without having to flow through a bend. In other words, the electrical current flow is separated from the cooling fluid flow in the region of the pair realized by the connecting device.

As a result, it is advantageously possible to dispense with complexly curved shaped conductors which have a narrowed cooling channel due to the bend. Likewise, there is no need for complex, high-precision bores in order to discharge the cooling fluid on one end face. The hairpin winding of the stator according to the invention can thus be designed with little effort and in a fluid-mechanical manner.

A hairpin winding in the context of the present invention is a winding that is formed from essentially rigid shaped conductors. The term “hairpin winding” is also known for hairpin winding, so that the term “hairpin” - also in word combinations - can be replaced by “hairpin”.

The shaped conductors are preferably each formed from a tube. The tube can, for example, have a circular, oval or polygonal, in particular rectangular, cross section.

The shaped conductors are particularly preferably designed to be straight over their entire extent. As a result, the shaped conductors can be produced without bending and, as it were, have an essentially constant internal cross section.

In the case of the stator according to the invention, it is preferred if the connecting device is attached to the exterior of a respective one of the shaped conductors. In this way, an arrangement formed from the shaped conductor and the connecting device can be produced in a simple manner. Alternatively or additionally, the connecting device is formed from a strip-shaped conductor. Such a conductor can advantageously be bent with little effort in such a way that a desired winding pattern can be implemented. The connecting device is typically formed in one piece. According to a preferred production-related embodiment, it is provided that the connecting device is materially connected to the shaped conductors, for example by welding.

In the stator according to the invention it can also be provided that one of the shaped conductors of a first of the pairs is electrically conductively connected to one of the shaped conductors of a second of the pairs by a second connecting device which is attached to the shaped conductors in an electrically conductive manner.

According to a first alternative development, it is provided that the second connecting device comprises a first connecting element that is electrically conductive attached to the molded conductor of the first pair, and a second connecting element that is electrically conductive attached to the molded conductor of the second pair, the first and the second Connecting element are attached to one another in an electrically conductive manner. The first and the second connecting element can therefore be fastened to the shaped conductors and to one another in an electrically conductive manner after the shaped conductors connected by the first connecting device have been introduced.

Analogous to the first connection device, it can be provided for the first connection element and / or the second connection element of the second connection device that the first connection element and / or the second connection element cannot be flowed through by the cooling fluid and / or is formed from a strip-shaped conductor and / or is made in one piece is and / or cohesively, preferably by welding, is connected to the form conductors.

According to a second alternative development, the second connecting device is designed in one piece. Here, too, it can be provided that the second connection device cannot be flowed through by the cooling fluid and / or is formed from a strip-shaped conductor and / or is connected to the shaped conductors in a materially bonded manner, preferably by welding.

In general, it is preferred if the second connecting device is attached in an electrically conductive manner to the exterior of the molded conductor of the first pair and to the molded conductor of the second pair.

Typically, the first connection devices are arranged on a first end face of the stator and the second connection devices are arranged on a second end face of the stator opposite the first end face.

The object on which the invention is based is further achieved by a method for producing a stator for an electrical machine, comprising the following steps: providing a stator core with stator slots which are arranged distributed in a circumferential direction with respect to a central axis of the stator core; Providing a plurality of pairs of shaped conductors through which a cooling fluid can flow; and inserting the pairs of shaped conductors into the stator slots, the shaped conductors of a respective pair being inserted into different stator slots; wherein the pairs are provided with a connection device through which the cooling fluid cannot flow and which connects the shaped conductors in an electrically conductive manner, or wherein the pairs are connected in an electrically conductive manner after insertion by a connection device through which the cooling fluid cannot flow.

The shaped conductors connected by means of the first connecting device are therefore provided in an already connected state in order to be introduced into the stator slots, typically from an end face of the stator core. At the other end face, open free ends of the shaped conductors then typically protrude.

The production method according to the invention preferably further comprises the following step: electrically conductive connection of one of the shaped conductors of a first of the pairs to one of the shaped conductors of a second of the pairs by a second connecting device. As a result, the shaped conductors of different pairs are connected in an electrically conductive manner in order to implement a predetermined winding scheme. The step is typically repeated multiple times for a plurality of first and second pairs.

According to a first preferred alternative, it is provided that the electrically conductive connection by means of the second connection device comprises the following steps: electrically conductive fastening of a first connection element of the second connection device to the shaped conductor of the first pair; electrically conductive fastening of a second connecting element of the second connecting device to the shaped conductor of the second pair; and electrically conductive connection of the first and second connecting element to each other.

The first and the second connecting element are preferably connected to one another by a materially bonded joining process, preferably by welding.

According to a second preferred alternative, a one-piece second connecting device is used.

Alternatively or additionally, it can be provided that the second connecting device is connected to the shaped conductor of the first pair and / or to the shaped conductor of the second pair by a material-locking joining process, in particular by welding.

All statements relating to the stator according to the invention can be applied analogously to the manufacturing method according to the invention, so that the aforementioned advantages can also be achieved with this. In particular, the shaped conductors, connecting devices and connecting elements described for the stator can be used in the context of the manufacturing method according to the invention.

The object on which the invention is based is also achieved by an electrical machine, comprising a stator according to the invention or a stator obtainable by the method according to the invention; and a cooling device which is configured to convey a cooling fluid through the shaped conductors.

The object on which the invention is based is finally also achieved by a vehicle comprising an electrical machine according to the invention, the electrical machine being set up to drive the vehicle.

• 1 eine stirnseitige Ansicht eines Ausführungsbeispiels der erfindungsgemäßen elektrischen Maschine;
• 2 eine perspektivische Ansicht eines Paares der Formleiter mit Verbindungsvorrichtungen gemäß dem Ausführungsbeispiel;
• 3 eine Draufsicht auf das Paar von Formleitern mit den Verbindungsvorrichtungen gemäß dem Ausführungsbeispiel; und
• 4 eine Prinzipskizze eines Ausführungsbeispiels des erfindungsgemäßen Fahrzeugs mit einem Ausführungsbeispiel der erfindungsgemäßen elektrischen Maschine.

Further advantages and details of the present invention emerge from the exemplary embodiments described below and on the basis of the drawings. These are schematic representations and show:

• 1 an end view of an embodiment of the electrical machine according to the invention;
• 2 a perspective view of a pair of shaped conductors with connecting devices according to the embodiment;
• 3 a plan view of the pair of shaped conductors with the connecting devices according to the embodiment; and
• 4th a schematic diagram of an embodiment of the vehicle according to the invention with an embodiment of the electrical machine according to the invention.

1 Figure 3 is an end view of one embodiment of a stator 1 . Here is the stator 1 shown in a state in which - connecting elements described in more detail below 10 , 11 (please refer 2 and 3 ) - are not yet connected.

The stator 1 includes a stator core 2 with a variety of stator slots 3 , where the number of stator slots 3 in the present example is forty-eight. The stator slots 3 are in a circumferential direction with respect to a central axis 4th of the stator core 2 arranged distributed and extending along an axial direction with respect to the central axis 4th .

The stator 1 further comprises a hairpin winding 5 with a plurality of shaped conductors that can be flown through by a cooling fluid and extend along the axial direction 6a , 6b . In the present embodiment, each stator slot 3 two radially shaped conductors with respect to the central axis 6a , 6b arranged.

2 and 3 each show a pair 7th of form managers 6a , 6b and a first connecting device 8th and each part of two second connecting devices 9a , 9b , in which 2 a perspective view and 3 is a plan view.

Every form manager 6a , 6b is formed from a tube, here exemplarily with a rectangular inner and outer profile, so that a cooling fluid can flow through it. The form manager 6a , 6b are over their entire extent, i.e. both within the stator slots 3 as well as outside the stator slots 3 , just trained. They therefore have no bends and the like.

The form manager 6a , 6b of the couple 7th are in two different stator slots 3 arranged at different radial positions. On a first end face that the in 1 opposite side shown the form manager 6a , 6b of the couple 7th by the first connecting device 8th electrically conductively connected. The first connecting device 8th is on the outside of the form ladder 6th attached and formed in one piece by a strip-shaped conductor. At the first connection device 8th it is therefore a massive conductor through which the cooling fluid cannot flow. This is the first connection device 8th on the form leaders 6a , 6b welded on or attached by means of another material-locking joining process. The first connecting device 8th is bent so that the shape of the ladder 6a , 6b of the couple 7th for realizing a desired winding scheme when it is introduced into the stator slots 3 are positioned to each other.

On the second face of the stator 1 is the form manager 6a of the in 2 and 3 shown pair 7th with a form manager 6b of a second pair by a second connecting device 9a electrically connected. The form manager is at the same time 6b of the couple 7th with a form manager 6a another pair by a further second connecting device 9b electrically connected. In the present exemplary embodiment, every second connecting device comprises 9a , 9b a first connecting element 10 , where in 2 and 3 the first connector 10 the second connecting device 9a and a second connector 11 , where in the 2 and 3 the second connecting element 11 the second connecting device 9b is shown. The fasteners 10 , 11 are each electrically conductive on the shaped conductor 6a or. 6b attached. The fasteners 10 , 11 are like the first connecting device 8th also made of a strip-shaped, solid conductor through which the cooling fluid cannot flow, formed in one piece and cohesively with the shaped conductors 6a , 6b attached to their exterior.

According to an alternative embodiment, the second are connecting devices 9a , 9b integrally formed so that they are the first connecting device 8th are similar, but different pairs of form conductors 6a , 6b connect.

• In einem ersten Schritt des Verfahrens wird ein Statorkern 2 mit Statornuten 3, die in einer Umfangsrichtung bezüglich einer Mittelachse 4 des Statorkerns 2 verteilt angeordnet sind, bereitgestellt. In einem weiteren Schritt des Verfahrens werden mehrere Paare 7 von durch ein Kühlfluid durchströmbaren Formleitern 6a, 6b, die durch eine nicht durch das Kühlfluid durchströmbare erste Verbindungsvorrichtung 8 elektrisch leitfähig verbunden sind, bereitgestellt. Die verbundenen Paare 7 von Formleitern 6a, 6b werden in einem folgenden Schritt in unterschiedliche Statornuten 3 eingeführt.

The following are exemplary embodiments of a method for producing a stator 1 described, with reference to 1 to 3 and identical reference symbols are used for identical or identically acting components:

• The first step in the process is to create a stator core 2 with stator slots 3 in a circumferential direction with respect to a central axis 4th of the stator core 2 are arranged distributed, provided. In a further step of the process, several pairs are made 7th of shaped conductors through which a cooling fluid can flow 6a , 6b through a first connection device through which the cooling fluid cannot flow 8th are electrically conductively connected, provided. The connected couples 7th of form managers 6a , 6b are in a following step in different stator slots 3 introduced.

The next step in the process is to become one of the form leaders 6a one of the first of the couples 7th with one of the form leaders 6b a second of the pairs by a second connecting device 9a connected.

According to a first exemplary embodiment of the method, this step comprises the following substeps: In a first substep, a first connecting element is created 10 the second connecting device 9a on the form manager 6a of the first couple 7th attached in an electrically conductive manner. In a second substep, a second connecting element is used 11 the second connecting device 9a on the form manager 6b of the second pair attached. In a third sub-step, the first connecting element 10 and the second connecting element 11 electrically conductively connected to one another.

According to a second exemplary embodiment of the method, when performing the step of connecting the shaped conductor 6a of the first of the couple 7th with the form manager 6b of the second of the pairs by the second connecting device 9a an integral second connector 9a used. This is the first sub-step on the form manager 6a of the first couple 7th Electrically conductive attached and in a second sub-step on the form conductor 6b of the second pair electrically conductive attached.

The aforementioned step is then carried out for further pairs with further second connection devices 9b repeated.

The electrically conductive fastening of the connecting devices 9a , 9b or the connection of the connecting elements 10 , 11 takes place by means of a cohesive joining process, here by welding.

According to further exemplary embodiments, which correspond to one of the aforementioned exemplary embodiments of the production method, only the pair 7th of form managers 6a , 6b provided and in the stator core 2 introduced. After insertion, the couple will 7th then by means of the first connection device through which the cooling fluid cannot flow 8th connected with each other.

4th Figure 3 is a schematic diagram of one embodiment of a vehicle 103 , comprising an electric machine 100 . The electric machine 100 is set up to do this, the vehicle 103 to drive. This is therefore an electric vehicle (BEV) or a hybrid vehicle.

The electric machine 100 includes a stator 101 according to one of the exemplary embodiments described above or a stator obtained by one of the exemplary embodiments of the manufacturing method 101 . The electric machine 100 further comprises a not shown rotatable within the stator 101 mounted rotor. It also includes the electrical machine 100 or the vehicle 103 a grant through which the cooling fluid, here a cooling oil, through the form conductor 6a , 6b (please refer 2 and 3 ) is eligible for funding.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 102017204472 A1 [0004]

Claims (15)

Stator (1) for an electrical machine (100), comprising - a stator core (2) with stator slots (3) which are arranged distributed in a circumferential direction with respect to a central axis (4) of the stator core (2), and - a hairpin winding (5) ); characterized in that the hairpin winding (5) comprises several pairs (7) of shaped conductors (6a, 6b) through which a cooling fluid can flow and which extend through two different stator slots (3), the shaped conductors (6a, 6b) of a respective pair (7) are electrically conductively connected to one end face of the stator (1) by a connecting device (8) which is fastened to the shaped conductors (6a, 6b) and through which the cooling fluid cannot flow. Stator after Claim 1 , wherein the shaped conductors (6a, 6b) are each formed from a tube and / or are straight over their entire extent. Stator according to one of the preceding claims, wherein the connecting device (8) - Is attached to the exterior of a respective one of the shaped conductors (6a, 6b) and / or - Is formed from a strip-shaped conductor and / or - Is formed in one piece and / or - Is firmly connected to the form conductors (6a, 6b). Stator according to one of the preceding claims, wherein one of the shaped conductors (6a) of a first of the pairs (7) is electrically conductively connected to one of the shaped conductors (6b) of a second of the pairs by a second connecting device (9a, 9b) attached to the shaped conductors (6a, 6b) is attached in an electrically conductive manner. Stator after Claim 4 , the second connecting device (9a, 9b) having a first connecting element (10) which is electrically conductive attached to the molded conductor (6a) of the first pair (7), and a second connecting element (11) which is electrically conductive to the molded conductor (6b) of the second pair is attached, wherein the first and the second connecting element (10, 11) are electrically conductively attached to one another. Stator after Claim 4 , wherein the second connecting device (9a, 9b) is formed in one piece. Stator according to one of the Claims 4 to 6th , wherein the second connecting device (9a, 9b) is electrically conductively attached to the exterior of the molded conductor (6a) of the first pair (7) and to the molded conductor (6b) of the second pair. A method for producing a stator (1) for an electrical machine (100), comprising the following steps: - Provision of a stator core (2) with stator slots (3) which are arranged distributed in a circumferential direction with respect to a central axis (4) of the stator core (2); - Provision of several pairs (7) of shaped conductors (6a, 6b) through which a cooling fluid can flow; and - Introducing the pairs (7) of shaped conductors (6a, 6b) into the stator slots (3), the shaped conductors (6a, 6b) of a respective pair (7) being introduced into different stator slots (3); wherein the pairs are provided with a connection device (8) through which the cooling fluid cannot flow and which connects the shaped conductors (6a, 6b) in an electrically conductive manner, or wherein the pairs are electrically conductively connected after insertion by a connection device (8) through which the cooling fluid cannot flow become. Manufacturing process according to Claim 8 , further comprising the following step: electrically conductive connection of one of the shaped conductors (6a) of a first of the pairs (7) to one of the shaped conductors (6b) of a second of the pairs by a second connecting device (9a, 9b). Manufacturing process according to Claim 9 , wherein the electrically conductive connection by means of the second connecting device (9a, 9b) comprises the following steps: - electrically conductive fastening of a first connecting element (10) of the second connecting device (9a, 9b) to the shaped conductor (6a) of the first pair (7); - electrically conductive fastening of a second connecting element (11) of the second connecting device (9a, 9b) to the shaped conductor (6b) of the second pair; and - electrically conductive connection of the first and second connecting elements (10, 11) to one another. Manufacturing process according to Claim 10 , wherein the first and the second connecting element (10, 11) are connected to one another by a material-locking joining process, preferably by welding. Manufacturing process according to Claim 9 using an integral second connecting device (9a, 9b). Manufacturing process according to one of the Claims 8 to 12th , the second connecting device (9a, 9b) being connected to the shaped conductor (6a) of the first pair (7) and / or to the shaped conductor (6b) of the second pair by a material-locking joining process, in particular by welding. Electrical machine (100), comprising - a stator (1, 101) according to one of the Claims 1 to 7th or by a method according to one of the Claims 8 to 13th available stator (1, 101); and - a cooling device which is set up to convey a cooling fluid through the shaped conductors (6a, 6b). Vehicle (103) comprising an electric machine (100) according to Claim 14 , wherein the electric machine (100) is set up to drive the vehicle (103).

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