DE102023107406A1 - STATOR FOR ELECTRIC MACHINE, ELECTRIC MACHINE AND MOTOR VEHICLE WITH THE ELECTRIC MACHINE - Google Patents

Abstract

A stator (1) is provided for an electric machine (10) of a motor vehicle, comprising at least one winding (3, 4), each of which is formed from turns of an electrically conductive wire and has a winding head (4). At least one winding section (5-1) of the windings, which forms at least a part of the winding head (4), has at least one cooling passage (6-1, 6-2, 6-3).

Description

The present disclosure relates to a stator for an electric machine of a motor vehicle, an electric machine comprising the stator, and/or a motor vehicle comprising the electric machine.

An electrical machine (a motor and/or a generator) usually consists of a stator and a rotor. The stator is the part that does not move and the rotor is the part that rotates. In most AC machines (synchronous machine, asynchronous machine, reluctance motor, etc.) there are windings in the stator that generate a rotating magnetic field. These windings usually consist of a copper wire that is usually either rectangular, with rounded corners, or completely round. So-called hairpin windings, endless windings or wave windings are often used. The windings comprise turns that are arranged close to one another on several levels and also have a constant cross-section and the same shape throughout.

For example, the usual way to make hairpin windings is to form the metal rods into a U-shape and then push them through the stator so that the two ends are on opposite sides of the stator. The protruding ends of the metal rods are then bent back together and welded together.

Overall, the protruding part of the windings is called the winding head and the inner part is called the active part. The winding head is not a part that is necessary for the function of the electrical machine or contributes to the performance, but rather is a by-product that is created during production. Ideally, it is therefore as small as possible.

One known way of cooling an electrical machine is to use a fluid or medium, such as oil. This fluid cools the electrical machine directly in the stator itself, and oil is also sprayed onto the winding head through small holes from the stator, whereby this can either happen from the outside to the inside or in combination from several sides.

However, such fluid cooling or other known cooling techniques may be inadequate for some designs of electrical machines, e.g. for electrical machines in which approximately 30% more heat must be dissipated in the winding head areas than in conventional electrical machines.

document EN 10 2021 104 590 A1 describes an electric machine for hybrid or electric vehicles, comprising a stator core, cross-linked windings of hairpin contacts and a terminal. The cross-linked windings of hairpin contacts are arranged between an inner diameter and an outer diameter of the core. The terminal has a first plate connected to a first pair of hairpin contacts arranged along the outer diameter of the core, a second plate connected to a second pair of hairpin contacts arranged along the inner diameter of the core, and a bridge plate extending between and connecting the first plate and the second plate.

document EN 10 2014 218 453 A1 describes an electric motor with oil cooling, with a rotor that can rotate about an axis, in which a coolant line is formed radially centrally along the axis, which has at least one radially extending discharge opening. At least one distributor wheel fixed to the rotor is provided for centrifugally conveying a coolant that can be discharged from the discharge opening.

document EP 3 044 857 A2 describes an electric motor or generator comprising a stator having stator teeth for mounting electrical coils, a rotor, a first electrical device for controlling the current in the electrical coils to produce a rotational torque on the rotor, and a second electrical device for modifying the current supplied to the first electrical device. The stator includes a cooling arrangement having a cooling channel arranged to cool the electrical coils, the first electrical device, and the second electrical device.

document EN 10 2020 109 282 A1 describes an electrical machine comprising a rotor and a stator, which has a stator body with a plurality of stator teeth arranged distributed around the circumference and stator slots formed between the stator teeth. Hairpins are arranged in the stator slots to form a hairpin winding, wherein a first group of hairpins has a shell surface which is profiled at least in some areas, such that a stator cooling channel running in the axial direction is formed between two hairpins arranged immediately adjacent in a stator slot.

Against the background of this prior art, the object of the present disclosure is to provide a device which is each suitable for enriching the prior art.

The problem is solved by the features of the independent claims. The subordinate claims and the dependent claims each contain optional further developments of the disclosure.

The task is then solved by a stator for an electrical machine of a motor vehicle.

The stator comprises at least one winding, each of which is formed from turns of an electrically conductive wire and has a winding head.

At least one winding section of the windings, which forms at least a part of the winding head, has at least one cooling passage.

The at least one winding can have an active part. The active part can be designed to surround a rotor of the electrical machine (e.g. radially) and/or to generate a magnetic field for driving (or rotating) the rotor. The winding head can be formed at outer ends of the active part (e.g. in the direction of a rotation axis of the rotor and/or in the longitudinal direction of the stator). The active part can be an inner part of the stator (e.g. in the direction of the rotation axis of the rotor and/or in the longitudinal direction of the stator) and the winding head can be an outer part of the stator.

The stator described above offers a number of advantages. Among other things, the stator offers improved cooling, since the surface and thus the cooling area of the winding head is increased by the at least one cooling passage. Furthermore, a cooling fluid can be distributed better in or on the winding head, which increases the cooling effect. In addition, material can be saved on the winding head.

In contrast, cooling in known stators takes place on the surfaces of the winding packs (also: conductor packs), because the windings (or the electrically conductive wire) are arranged so close to one another that the cooling fluid cannot penetrate into the interior of the winding pack. This results in a much poorer cooling effect than is possible.

Possible further developments of the device described above are explained in detail below.

The at least one cooling passage may comprise a plurality of cooling passages spaced apart in the direction of the at least one winding section.

At least some of the plurality of cooling passages may have different shapes and/or cross-sectional sizes.

The electrically conductive wire can have a plate-shaped course (and/or a rectangular cross-sectional shape). The at least one cooling passage can extend in the height direction of the electrically conductive wire and/or the at least one winding section.

The winding head can be formed (at least partially) from winding sections of several of the windings arranged one behind the other. The winding sections can have cooling passages arranged one behind the other to form a cooling channel. This means that the winding head or the winding package can also be cooled from the inside in an advantageous manner, which, for example, allows more control over the flow of cooling fluid and/or the stator is cooled more evenly.

The stator may comprise fluid cooling. The at least one cooling passage may be designed as part of the fluid cooling and/or for guiding a cooling fluid. The cooling fluid may comprise an oil.

The at least one winding can be designed as a hairpin winding.

The electrically conductive wire can have a cross-sectional size and/or cross-sectional shape that changes in the direction of its extension. The stator can advantageously be improved with regard to various possible factors, e.g. with regard to a reduction in power losses (e.g. AC losses, DC losses), a reduced material consumption and/or an improved cooling effect.

A first winding section of the electrically conductive wire, which forms the active part at least in sections, can have a different cross-sectional size and/or cross-sectional shape than a second winding section of the electrically conductive wire, which forms the winding head at least in sections. The at least one winding section can, for example, comprise the second winding section or correspond to the second winding section.

The second winding section can have a smaller cross-sectional size than the first winding section. This advantageously allows material to be saved on the winding head and thus in the area that is less relevant for the function of the stator (or the electrical machine).

The second winding section can have a larger cross-sectional size than the first winding section. This advantageously makes it possible to provide a larger surface on the winding head for improved cooling, which can be sprayed with a cooling fluid, for example, thus improving the cooling effect.

The first winding section can have a polygonal cross-sectional shape and the second winding section can have a rounded cross-sectional shape, wherein optionally a cross-sectional size of the first winding section and a cross-sectional size of the second winding section are the same. This advantageously makes it possible to achieve a higher filling density of the active part and at the same time an improved cooling effect on the winding head, wherein, for example, cooling fluid can better pass through different layers of the winding head.

The first winding portion may have a rectangular cross-sectional shape and the second winding portion may have a circular (or oval) cross-sectional shape.

The cross-sectional size and the cross-sectional shape of the first winding section can be constant along the entire first winding section. The cross-sectional size and the cross-sectional shape of the second winding section can be constant along the entire second winding section.

The first winding section and the second winding section can merge directly into one another.

The first winding section and the second winding section can, for example, each have a length of at least 1 cm.

Several, optionally all, turns can be designed identically and/or each have the first turn section and the second turn section. Several first turn sections can be arranged adjacent to one another and/or one behind the other. Several second turn sections can be arranged adjacent to one another and/or one behind the other.

The active part can be formed from a plurality of winding sections of the electrically conductive wire. The plurality of winding sections can have at least partially different cross-sectional sizes and/or cross-sectional shapes.

The electrically conductive wire can have a cross-sectional size and/or cross-sectional shape that changes in the direction of travel in an unwound state and/or an unprocessed state (e.g. without openings and notches).

The electrically conductive wire can be made of metal, e.g. copper. The electrically conductive wire can also be referred to as an (electrical) conductor.

The fluid cooling can be designed to cool, e.g. spray, at least one surface of the winding head with a cooling fluid.

The above can be summarized in other words and in a possible more concrete embodiment of the disclosure as described below, whereby the following description is not to be interpreted as limiting the disclosure.

According to the present disclosure, holes, i.e. cooling passages, can be provided or formed in the winding head of the stator.

The holes can be implemented in any number, shape, position and orientation (e.g. round, rectangular, horizontal, vertical, many small, few large, etc.). Likewise, different types of holes can be used together. This can open up many new possibilities to improve the cooling of the stator.

The holes can be used to form a kind of channel that can run through the different levels of windings, making it possible to cool the conductor packages from the inside. This makes the flow of cooling fluid more controllable, so that the stator can be cooled evenly, for example.

The holes increase the surface area of the windings in the area of the winding head(s), which allows for more contact with the cooling fluid and thus a greater heat exchange, which can ultimately ensure improved cooling. Depending on how (exactly) the cooling, e.g. oil cooling, is implemented, the holes can be adapted and arranged differently accordingly.

Possible power losses due to a cross section of the windings passing through the holes can be compensated for in other ways, for example by saving energy through more efficient use of the cooling fluid.

Furthermore, an electric machine for a motor vehicle is provided, wherein the electric machine comprises the stator described above.

The electric machine can further comprise a rotatably mounted rotor. The stator can radially surround the rotor.

The stator and/or the electrically conductive wire can be subjected to an electrical voltage to generate a magnetic field. The magnetic field can be aligned to cause the rotor to rotate.

The electrical machine can be operated as a motor and/or as a generator.

What is described above with reference to the stator also applies analogously to the electrical machine and vice versa.

Furthermore, a motor vehicle is provided, wherein the motor vehicle comprises the electric machine (and/or the stator described above).

The motor vehicle may be a passenger car, in particular an automobile, or a commercial vehicle, such as a truck.

The motor vehicle can be an electrically driven, optionally drivable, motor vehicle. The electric machine can be part of an electric drive device of the motor vehicle.

What is described above with reference to the stator and the electric machine also applies analogously to the motor vehicle and vice versa.

• 1 zeigt schematisch eine offenbarungsgemäße elektrische Maschine,
• 2 zeigt schematisch einen Ausschnitt eines Wickelkopfs eines Stators gemäß einer Ausführungsform, und
• 3 zeigt schematisch einen ersten Windungsabschnitt und einen zweiten Windungsabschnitt gemäß zwei Ausführungsformen.

Below, optional embodiments are described with reference to 1 , 2 and 3 described.

• 1 shows schematically an electrical machine according to the disclosure,
• 2 shows schematically a section of a winding head of a stator according to an embodiment, and
• 3 schematically shows a first winding section and a second winding section according to two embodiments.

The 1 The electrical machine 10 for a motor vehicle, which is shown only schematically, comprises a conventional structure consisting of a rotatably mounted rotor 2 and a stator 1 radially surrounding the rotor 2.

The stator 1 comprises at least one winding, each of which is formed from turns of an electrically conductive wire. By applying an electrical voltage to the stator 1, a magnetic field can be generated which can set the rotor 2 in rotation. The at least one winding can be designed as a hairpin winding, for example.

The at least one winding has an active part 3 and (at least) one winding head 4. The active part 3 surrounds the rotor 2, wherein the magnetic field that drives the rotor 2 to rotate can be generated essentially by the active part 3. The winding head 4 can be formed at outer ends of the stator 1 in the direction of a rotation axis of the rotor 1 or in the longitudinal direction of the stator 1 and is essentially a by-product that arises during the manufacture of the rotor 2 or the at least one winding.

In 2 schematically shows a section of the winding head 4 according to an embodiment.

As shown, the inner part 3 (and also the rotor 2) can be enclosed by a housing 8. The winding head 4, which is formed by the winding sections 5-1, 5-2 and 5-3, among others, can be arranged outside the housing 8, wherein the turns of the at least one winding are guided through openings in the housing 8 to form the winding head 4.

A winding section 5-1 of the windings, which forms at least a part of the winding head 4, has at least one cooling passage 6-1, 6-2, 6-3, e.g., as shown, a plurality of cooling passages 6-1, 6-2, 6-3 spaced apart in the direction of the winding section 5-1.

At least a portion of the plurality of cooling passages 6-1, 6-2, 6-3 may have different shapes and/or cross-sectional sizes. For example, as shown, the cooling passage 6-1 may have a rectangular shape and the cooling passages 6-2 and 6-3 may have a round shape.

The electrically conductive wire can have a plate-shaped course and the at least one cooling passage 6-1, 6-2, 6-3 can extend in the height direction of the electrically conductive wire or the winding section 5-1.

The winding head 4 is formed from several winding sections of several of the windings det, among other things, the winding sections 5-1, 5-2, 5-3 arranged one behind the other. These winding sections 5-1, 5-2, 5-3 can have cooling passages arranged one behind the other to form a cooling channel. For example, the winding sections 5-2 and 5-3 can have cooling passages which are formed coaxially to the cooling passages 6-1, 6-2, 6-3.

The stator 1 can further comprise a fluid cooling system, wherein the at least one cooling passage 6-1, 6-2, 6-3 can be designed as part of the fluid cooling system and/or for guiding a cooling fluid.

Alternatively, or in addition to the at least one cooling passage 6-1, 6-2, 6-3, the electrically conductive wire can be designed such that it has a cross-sectional size and/or cross-sectional shape that changes in the direction of travel, e.g. in an unwound state and/or an unprocessed state. Two possible embodiments are shown schematically and by way of example in 3 shown.

Thus, a first winding section 7-1, 7-2 of the electrically conductive wire, which forms the active part 3 at least in sections, can have a different cross-sectional size and/or cross-sectional shape than a second winding section 5-4, 5-5 of the electrically conductive wire, which forms the winding head 4 at least in sections.

As in (a) the 3 For example, the second winding section 5-4 may have a smaller cross-sectional size than the first winding section 7-1. As shown in (b) of the 3 As shown, the second winding section 5-5 may alternatively have a larger cross-sectional size than the first winding section 7-2.

The first winding section 7-1, 7-2 can have a polygonal, e.g. rectangular, cross-sectional shape and the second winding section 5-4, 5-5 can have a rounded, e.g. circular, cross-sectional shape.

It is also conceivable that the active part 3 can be formed from a plurality of winding sections of the electrically conductive wire, wherein the plurality of winding sections can have at least partially different cross-sectional sizes and/or cross-sectional shapes.

List of reference symbols

1

stator

2

rotor

3

active part of the winding

4

Winding head of the winding

5-1, 5-2, 5-3 5-4, 5-5

Winding section which forms the winding head at least in sections

6-1, 6-2, 6-3

Cooling passage

7-1, 7-2

Winding section which forms the active part at least in sections

8

Housing

10

electric machine

QUOTES INCLUDED IN THE DESCRIPTION

This list of 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 accepts no liability for any errors or omissions.

Cited patent literature

• DE 102021104590 A1 [0007]
• DE 102014218453 A1 [0008]
• EP 3044857 A2 [0009]
• DE 102020109282 A1 [0010]

Claims (10)

Stator (1) for an electrical machine (10) of a motor vehicle, comprising: - at least one winding (3, 4), each of which is formed from turns of an electrically conductive wire and has a winding head (4), characterized in that - at least one winding section (5-1) of the windings, which forms at least a part of the winding head (4), has at least one cooling passage (6-1, 6-2, 6-3). Stator (1) after Claim 1 , characterized in that the at least one cooling passage comprises a plurality of cooling passages (6-1, 6-2, 6-3) spaced apart in the direction of the at least one winding section (5-1). Stator (1) after Claim 2 , characterized in that at least a part of the plurality of cooling passages (6-1, 6-2, 6-3) have different shapes and/or cross-sectional sizes. Stator (1) according to one of the preceding claims, characterized in that the electrically conductive wire has a plate-shaped course and the at least one cooling passage (6-1, 6-2, 6-3) extends in the height direction of the electrically conductive wire and/or the at least one winding section (5-1). Stator (1) according to one of the preceding claims, characterized in that the winding head (4) is formed from winding sections (5-1, 5-2, 5-3) of several of the windings arranged one behind the other, wherein the winding sections (5-1, 5-2, 5-3) have cooling passages arranged one behind the other for forming a cooling channel. Stator (1) according to one of the preceding claims, characterized in that the stator (1) comprises a fluid cooling system, wherein the at least one cooling passage (6-1, 6-2, 6-3) is designed as part of the fluid cooling system and/or for guiding a cooling fluid. Stator (1) according to one of the preceding claims, characterized in that the electrically conductive wire (7-1, 5-4, 7-2, 5-5) has a cross-sectional size and/or cross-sectional shape that changes in the direction of its extension. Stator (1) according to one of the preceding claims, characterized in that the at least one winding (3, 4) is designed as a hairpin winding. Electric machine (10) for a motor vehicle, characterized in that the electric machine (10) comprises the stator (1) according to one of the preceding claims. Motor vehicle, characterized in that the motor vehicle has the electric machine (10) according to Claim 9 includes.

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