DE102019218582A1 - Electric machine with cooling device - Google Patents

Abstract

The invention relates to an electric machine (1) for a motor vehicle (2), having a rotor (4) rotatable about a machine longitudinal axis (3) and a stator (5), the stator (5) having a stator base body (6) and one on the stator base body (6) arranged coil winding (7) made of coil wire (8), the coil winding (7) having an end winding (9), with free spaces (10) being formed in the end winding (9) between adjacent coil wire sections, and wherein the electric machine (1 ) has a cooling device (11) in the area of the end winding (9). The cooling device (11) has a cooling base body (12) and a plurality of engagement elements (13) arranged on the cooling base body (12), the engagement elements (13) extending into the free spaces (10) of the end winding (9). The invention also relates to a motor vehicle (2) with a drive system (19), the drive system (19) having an electric machine (1) according to the invention.

Description

The present invention relates to an electric machine for a motor vehicle, having a rotor that can be rotated about a machine longitudinal axis and a stator. The stator has a stator base body and a coil winding made of coil wire and arranged on the stator base body, the coil winding having an end winding. In the end winding, free spaces are formed between adjacent coil wire sections. In addition, the electric machine has a cooling device in the area of the end winding. The invention also relates to a motor vehicle with a drive system.

It is known that electrical machines generate heat during operation and often have cooling devices to improve performance and to protect the components. In the case of cooling devices, a distinction is made in particular between cooling devices with an open cooling system and cooling devices with a closed cooling system. In addition, hybrid cooling devices are known which have both an open cooling system and a closed cooling system.

In the case of open cooling systems, the components of the electric machine are acted upon directly with a cooling fluid such as air, a cooled oil or the like. For this purpose, the cooling system has, for example, a nozzle through which the cooling fluid can flow out against the component to be cooled. Open cooling systems have the disadvantage that the cooling effect is often insufficient. For compensation, for example, a particularly high volume flow of the supplied cooling fluid must be set. Furthermore, the cooling fluid can lead to additional friction losses in the electric machine, in particular due to the penetration of oil into the air gap between rotor and stator and / or foaming of the oil. Finally, there may be potential incompatibilities between the cooling fluid and the electrical machine's insulation and sealing materials.

Cooling devices with a closed cooling system are designed in such a way that there is no direct contact between the cooling fluid and the components to be cooled. The cooling fluid can be used to cool a cooling body which cools the components to be cooled through direct contact or via an intermediate medium, such as a potting compound, an air gap or the like. An electric machine with a closed cooling system is, for example, from the DE 10 2013 210 311 A1 known. The electric machine has a stator with a plurality of stator teeth, on each of which a coil winding is arranged. In the area of a winding head of the stator, shim elements are arranged between the stator teeth, the shim elements being thermally connected to a stator housing. The DE 10 2018 102 750 A1 discloses a stator for an induction machine, in which a cooling element of a cooling device is pressed against an end face of an end winding by means of a spring device. The cooling device is thermally connected to a housing of the induction machine. From the DE 10 2018 102 740 A1 a rotary field machine with a stator is known, the stator having a plurality of stator teeth having windings. A cooling device of the induction machine has intermediate elements which are arranged between adjacent stator teeth and are designed to transport heat.

Known electrical machines with cooling devices that have a closed cooling system have the disadvantage that cooling of the end windings is only guaranteed over a very limited surface. To compensate for this, a cooling capacity of the cooling device must be increased and / or a poorer efficiency of the electric machine must be accepted.

It is therefore the object of the present invention to eliminate or at least partially eliminate the disadvantages described above in an electric machine for a motor vehicle. In particular, it is the object of the present invention to create an electric machine for a motor vehicle and a motor vehicle with an electric machine, which ensure improved cooling and / or an improved efficiency of the electric machine in a simple and inexpensive manner.

The above problem is solved by the patent claims. Accordingly, the object is achieved by an electric machine for a motor vehicle with the features of independent claim 1 and by a motor vehicle with an electric machine with the features of the independent claim 10. Further features and details of the invention emerge from the subclaims, the description and the drawings. Features and details that are described in connection with the electric machine according to the invention naturally also apply in connection with the motor vehicle according to the invention and vice versa, so that, with regard to the disclosure, reference is or can always be made to the individual aspects of the invention.

According to a first aspect of the invention, the object is achieved by an electric machine for a motor vehicle. The electric machine has one that can be rotated about a machine longitudinal axis Rotor and a stator, wherein the stator has a stator base body and a coil winding arranged on the stator base body made of coil wire. The coil winding has an end winding, with free spaces being formed in the end winding between adjacent coil wire sections. The electric machine has a cooling device in the area of the end winding. According to the invention, the cooling device has a cooling base body and a plurality of engagement elements arranged on the cooling base body, the engagement elements extending into the free spaces of the end winding.

The rotor preferably has a rotatably mounted rotor shaft with an active part, the active part preferably having a plurality of permanent magnets, which are preferably arranged in cutouts in the rotor shaft or in a magnet carrier formed for this purpose. As an alternative to permanent magnets, the rotor can have magnetic coils. According to the invention, it can be provided that the rotor has one or more cooling channels for cooling the rotor. The cooling channels are designed to allow a cooling fluid, such as oil, to pass through.

The stator base body preferably has a multiplicity of stator laminations which are assembled to form a laminated core. The adjacent stator laminations are preferably electrically insulated from one another, in particular by means of a lacquer layer or the like.

The coil winding is arranged on the stator base body and held by it. A coil winding is understood to mean an arrangement of a coil wire which is designed to generate an intensified magnetic field. This can be, for example, an actual winding or a winding-like arrangement of coil wire segments, which is generated, for example, by targeted arrangement and electrical coupling on the winding heads, in particular by welding, soldering or the like, of the coil wire segments. The adjacent coil wire sections or coil wire segments are preferably electrically insulated from one another, in particular by means of a layer of lacquer. Furthermore, it is preferred that the adjacent coil wire sections or coil wire segments are arranged at a distance from one another. The coil winding preferably extends parallel to the longitudinal axis of the machine, so that the opposite end regions of the coil winding each form a winding head.

In the end winding, the adjacent coil wire sections are arranged at a distance from one another and thus form free spaces. The free spaces preferably extend parallel to the machine longitudinal axis or have at least one extension component parallel to the machine longitudinal axis. In other words, according to the invention, the free spaces can also extend obliquely to the longitudinal axis of the machine. The free spaces can, for example, have a square or rectangular cross section. The adjacent coil wire sections in the end winding are preferably at a greater distance from one another than in other areas of the coil winding. This can be produced, for example, by a corresponding cranking of the coil wire.

The cooling base body is preferably arranged on the end face on the end winding. The cooling base body is preferably designed in the form of a plate and / or ring. The cooling base body preferably has a material with particularly advantageous thermal conductivity properties, such as, for example, special composite materials or metal, in particular copper, aluminum or the like, or is formed from such a material. A base body end face facing the winding head is preferably adapted to a surface contour of the winding head in order to ensure the greatest possible heat transfer from the winding head to the cooling base body. According to the invention, it can be provided that the cooling base body makes contact with the end winding. It is preferred here that the cooling base body is electrically insulated from the winding head, in particular the coil wire of the winding head, for example by means of a lacquer, casting resin or the like. The material used for electrical insulation preferably has at least average thermal conductivities.

The engagement elements of the cooling device extend from the cooling base body into the free spaces of the end winding. This means that an engagement element is arranged between several coil wire sections in the winding head. The engagement elements preferably have a shape and size corresponding to the respective free space. This means, for example, that a shape of a cross-section of an engagement element preferably corresponds to a cross-sectional shape of a free space. Preferably, a cross-sectional area of the engagement element is slightly smaller than a cross-sectional area of the free space in order to improve the arrangement of the engagement element in the free space. For improved mountability, the engagement elements preferably have a taper in the direction of an end facing away from the cooling base body.

The engagement elements extend with an extension component parallel to the machine longitudinal axis into the end winding between the coil wire sections. It is preferred that the engagement elements at least over half the length of the winding head with respect to the The longitudinal axis of the machine extends into the end winding. More preferably, the engagement elements extend over 70%, particularly preferably over 90%, into the end winding. The engagement elements are preferably made from the same material as the cooling base body. The engagement elements are particularly preferably monolithic with the cooling base body.

According to the invention, it is preferred that the stator each have a winding head at two opposite ends, the electric machine preferably having such a cooling device on each winding head, the engagement elements engaging in the free spaces of the winding heads. More preferably, the electric machine has further cooling devices, such as a machine housing cooling device, a rotor cooling device, a stator base body cooling device or the like.

An electrical machine according to the invention has the advantage over conventional electrical machines that improved cooling of the stator, in particular the end windings of the stator, is provided with simple means and in a cost-effective manner. Heat can be dissipated directly from the winding wire via the engagement elements, so that heating of surrounding components of the electrical machine, such as the stator base body or the rotor, can be avoided. Direct cooling of the winding wire in the area of the winding heads means that heat can be dissipated at the point where it is generated. An efficiency of the cooling device and an efficiency of the electric machine can thus be improved.

According to a preferred further development of the invention, it can be provided in an electrical machine that the coil winding is designed as a hairpin winding, plugged winding, individual winding or as a single tooth winding. In a hairpin winding, the winding wire has several wire sections, preferably with a rectangular or square cross section, which are arranged on the stator base body and electrically coupled to one another, for example soldered or welded, in the area of the winding heads to form the coil winding. In the case of a single-tooth winding, the stator base body has a plurality of stator teeth which extend radially to the longitudinal axis of the machine, the coil winding being arranged on the stator teeth. A hairpin winding has the advantage that the creation of defined free spaces between adjacent coil wire sections is improved. As a result, the assembly of the electric machine and the efficiency of the cooling device and thus also the efficiency of the electric machine are improved with simple means and in a cost-effective manner. A single-tooth winding with free spaces between adjacent coil wire sections on the winding heads can also be produced with simple means and in a cost-effective manner.

It is preferred according to the invention that the engagement elements have a material which has better thermal conductivity than the stator base body. The material preferably has better thermal conductivity than conventional potting material. According to the invention, improved thermal conductivity is understood to mean the property of dissipating heat more quickly than materials with poorer thermal conductivity. According to the invention, materials such as copper, aluminum or composite materials with improved thermal conductivity are particularly preferred for this purpose. Such a material has the advantage that heat transfer from the coil wire to the cooling base body is improved with simple means and in a cost-effective manner.

The engagement elements are furthermore preferably insulated from the coil wire by means of electrical insulation. The electrical insulation can be designed, for example, as a coating, such as, for example, a lacquer, of the coil wire and / or the engagement elements. As an alternative or in addition, the electrical insulation can have a potting compound, such as, for example, casting resin, in particular filled or unfilled epoxy resin, silicone, non-hardening TIM or the like. Electrical insulation has the advantage that the engagement elements prevent short-circuiting of the coil winding by simple means and in a cost-effective manner.

In a particularly preferred embodiment of the invention, the engagement elements thermally contact the coil wire via the electrical insulation. This preferably means that there is a direct contact between the engagement elements, the electrical insulation and the coil wire at least at one point, preferably at several points or over a larger area, via which a direct heat exchange can take place. This has the advantage that heat removal from the coil wire to the cooling base body is improved with simple means and in a cost-effective manner. Furthermore, relative movements of the cooling device to the end winding can be reduced in an advantageous manner by means of such contacts. Alternatively, it can be provided according to the invention that a gap is formed between the engagement elements and an adjacent coil wire section. This has the advantage that, with simple means and in a cost-effective manner, the introduction of the engagement elements into the free spaces is improved during the assembly of the electric machine. Moreover, in this way the risk of short circuit is the Coil winding can be reduced by the engagement elements.

The engagement elements are preferably designed in the shape of a scoop, rib or pin. Shovel-shaped engagement elements preferably have a relatively small end face and two side faces facing away from one another and relatively large. According to the invention, the side surfaces can, for example, have a curvature. Rib-shaped or pin-shaped engagement elements preferably have a round or square, especially square or diamond-shaped cross section. The engagement elements are preferably arranged in a star shape or in a rib shape on the cooling base body. Such engagement elements can be produced inexpensively and are particularly suitable for heat exchange with the coil wire.

According to a preferred embodiment of the invention, cooling channels for the passage of a cooling fluid are formed in the engagement elements. The cooling channels formed in the engagement elements are preferably connected to a closed cooling circuit. It is preferred that cooling channels are additionally or alternatively formed in the cooling base body. The cooling channels formed in the basic cooling body are preferably connected to a closed cooling circuit. The cooling channels formed in the engagement elements are preferably coupled in a fluid-communicating manner to the cooling channels formed in the cooling base body. This has the advantage that heat removal from the engagement elements and thus from the winding wire via the winding heads is improved with simple means and in a cost-effective manner.

The cooling base body of the cooling device particularly preferably has a cooling plate arranged at the end of the end winding, the cooling plate preferably having cooling fins extending away from the end winding and / or a cooling fluid channel for passing a cooling fluid through. The engagement elements are preferably thermally connected to the cooling plate. The cooling plate preferably makes contact with the coil winding in the area of the winding head. Heat can be dissipated from the cooling device to the environment via the cooling fins. The electric machine preferably has a fan for generating an air flow flowing towards the cooling fins. The cooling fluid channel preferably extends over the cross section of the cooling plate in such a way that the cooling of the cooling plate is guaranteed to be as large as possible. For example, an additional cooling device can be provided for particularly advantageous cooling of the cooling fluid.

Furthermore, an electrical or electronic component of the electrical machine is preferably arranged on the cooling plate. The electrical or electronic component can be designed, for example, as a control device, sensor, in particular speed sensor and / or temperature sensor, protective circuit or the like. A plurality of electrical or electronic components of the electrical machine are preferably arranged on the cooling plate. The electrical or electronic component is preferably arranged in a receiving cavity of the cooling plate. The plurality of electrical or electronic components are preferably arranged in one or more receiving cavities of the cooling plate. This has the advantage that improved cooling of the electrical or electronic components is ensured with simple means and in a cost-effective manner. The risk of these components overheating is thus considerably reduced.

According to a second aspect of the invention, the object is achieved by a motor vehicle with a drive system. According to the invention, the drive system has an electric machine according to one of the preceding claims. The drive system preferably has a plurality of electrical machines according to the invention, which are preferably each designed to drive one wheel or two wheels. In addition, the motor vehicle preferably has the usual components of a conventional motor vehicle, such as transmission, brake system, steering system, traction battery, on-board computer or the like.

The motor vehicle according to the invention has all the advantages that have already been described for an electric machine according to the first aspect of the invention. Accordingly, the motor vehicle according to the invention has the advantage over conventional motor vehicles that improved cooling of the stator, in particular the end windings of the stator, is provided with simple means and in a cost-effective manner. Heat can be dissipated directly from the winding wire via the engagement elements, so that heating of surrounding components of the electrical machine, such as the stator base body or the rotor, can be avoided. Direct cooling of the winding wire in the area of the winding heads means that heat can be dissipated at the point where it is generated. An efficiency of the cooling device and an efficiency of the electric machine can thus be improved.

• 1 in einer Seitenansicht eine bevorzugte erste Ausführungsform einer erfindungsgemäßen Elektromaschine,
• 2 in einer Schnittdarstellung eine an einem Wickelkopf angeordnete Kühlvorrichtung gemäß einer bevorzugten zweiten Ausführungsform einer erfindungsgemäßen Elektromaschine,
• 3 in einer Schnittdarstellung eine Kühlvorrichtung gemäß einer bevorzugten dritten Ausführungsform einer erfindungsgemäßen Elektromaschine,
• 4 in einer Schnittdarstellung eine Kühlvorrichtung gemäß einer bevorzugten vierten Ausführungsform einer erfindungsgemäßen Elektromaschine,
• 5 in einer Schnittdarstellung eine Kühlvorrichtung gemäß einer bevorzugten fünften Ausführungsform einer erfindungsgemäßen Elektromaschine, und
• 6 in einer Seitenansicht eine bevorzugte Ausführungsform eines erfindungsgemäßen Kraftfahrzeugs.

An electric machine according to the invention and a motor vehicle according to the invention are explained in more detail below with reference to drawings. They each show schematically:

• 1 in a side view a preferred first embodiment of an electric machine according to the invention,
• 2 in a sectional view a cooling device arranged on an end winding according to a preferred second embodiment of an electrical machine according to the invention,
• 3rd in a sectional view a cooling device according to a preferred third embodiment of an electric machine according to the invention,
• 4th in a sectional view a cooling device according to a preferred fourth embodiment of an electric machine according to the invention,
• 5 in a sectional view a cooling device according to a preferred fifth embodiment of an electric machine according to the invention, and
• 6th in a side view a preferred embodiment of a motor vehicle according to the invention.

Elements with the same function and mode of operation are in the 1 to 6th each provided with the same reference numerals.

In 1 is a preferred first embodiment of an electric machine according to the invention 1 for a motor vehicle (cf. 6th ) shown schematically in a side view. The electric machine 1 has a rotor 4th , which can be rotated around a longitudinal axis of the machine 3rd is stored. The rotor 4th preferably has an active part on which permanent magnets (not shown) are arranged. The rotor 4th is formed by a stator coaxial with the rotor 5 surround. The stator 5 has a stator body 6th as well as one the stator base body 6th arranged coil winding 7th made of coil wire 8th on. The stator body 6th is preferably designed as a laminated core from a large number of stator laminations arranged next to one another. The stator winding 7th is essentially parallel to the machine's longitudinal axis 3rd arranged. The stator winding faces at opposite end regions 7th one winding head each 9 on. In the end winding, there are free spaces between adjacent stator wire sections 10 educated.

In the open spaces 10 engage engagement elements 13th a cooling device 11 the electric machine 1 a. The cooler 11 has one as a cooling body 12th trained cooling plate 15th which on the end of the winding head 9 is arranged. In this preferred first embodiment there is a cooling device on each end of the two winding heads 11 arranged. The engaging elements 13th extend from the heat sink 12th parallel to the machine's longitudinal axis 3rd into the coil winding 7th of the winding head 9 into it, so that the engaging elements from several sides of coil wire 8th are surrounded. In a cooling plate 15th is a receiving cavity 18th formed in which an electronic component 17th the electric machine is arranged.

2 shows one on an end winding 9 arranged cooling device 11 according to a preferred second embodiment of an electric machine according to the invention 1 . The heat sink 12th the cooling device 11 is as an annular cooling plate 15th formed and has a cooling fluid channel 14th for passing a cooling fluid on. The engaging elements 13th extend into open spaces 10 of the winding head 9 of the stator 5 into it. The free spaces 10 are between adjacent coil wires 8th or coil wire sections on the stator base body 6th arranged coil winding 7th educated. On an end face of the cooling body facing away from the winding head 12th are electronic components 17th arranged.

In 3rd is a cooling device 11 according to a preferred third embodiment of an electric machine according to the invention 1 shown schematically in a side view. The heat sink 12th the cooling device 11 is as an annular cooling plate 15th formed and has a cooling fluid channel 14th for passing a cooling fluid on. The engaging elements 13th are peg-shaped and extend from the cooling body 12th path.

4th shows a cooling device 11 according to a preferred fourth embodiment of an electric machine according to the invention 1 schematically in a side view. The heat sink 12th the cooling device 11 is as an annular cooling plate 15th formed and has a cooling fluid channel 14th for passing a cooling fluid on. The engaging elements 13th are shovel-shaped and extend from the cooling body 12th path.

In 5 is a cooling device 11 according to a preferred fifth embodiment of an electric machine according to the invention 1 shown schematically in a side view. The heat sink 12th the cooling device 11 is as an annular cooling plate 15th formed and has a cooling fluid channel 14th for passing a cooling fluid on. The cooling fins 16 are shovel-shaped and arched and extend from the cooling body 12th path.

On one of the cooling fins 16 opposite end face of the cooling body 12th are two engagement elements 13th arranged parallel to the machine's longitudinal axis 3rd extend.

6th shows a preferred embodiment of a motor vehicle according to the invention 2 schematically in a side view. The car 2 exhibits a drive system 19th with four electrical machines according to the invention 1 on, being on each wheel of the motor vehicle 2 one electric machine each 1 of the drive system 19th is arranged. In an alternative embodiment, the motor vehicle 2 an electric machine according to the invention as the central machine 1 on, which is preferably arranged in a front region of the motor vehicle.

List of reference symbols

1

Electric machine

2

Motor vehicle

3

Machine longitudinal axis

4th

rotor

5

stator

6th

Stator body

7th

Coil winding

8th

Coil wire

9

Winding head

10

free space

11

Cooling device

12th

Heat sink

13th

Engagement element

14th

Cooling fluid channel

15th

Cooling plate

16

Cooling fin

17th

electronic component

18th

Receiving cavity

19th

Drive system

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 102013210311 A1 [0004]
• DE 102018102750 A1 [0004]
• DE 102018102740 A1 [0004]

Claims (10)

Electric machine (1) for a motor vehicle (2), comprising a rotor (4) rotatable about a machine longitudinal axis (3) and a stator (5), the stator (5) having a stator base body (6) and one on the stator base body (6) Has coil winding (7) made of coil wire (8), the coil winding (7) having a winding head (9), with free spaces (10) being formed in the winding head (9) between adjacent coil wire sections, and the electric machine (1) in the area of the The end winding (9) has a cooling device (11), characterized in that the cooling device (11) has a cooling base body (12) and several engagement elements (13) arranged on the cooling base body (12), the engagement elements (13) extending into the free spaces ( 10) of the winding head (9) extend. Electric machine (1) after Claim 1 , characterized in that the coil winding (7) is designed as a hairpin winding, plugged winding, pull-in winding or as a single-tooth winding. Electric machine (1) after Claim 1 or 2 , characterized in that the engagement elements (13) have a material which has a better thermal conductivity than the stator base body (6). Electric machine (1) according to one of the preceding claims, characterized in that the engagement elements (13) are insulated from the coil wire (8) by means of electrical insulation. Electric machine (1) after Claim 4 , characterized in that the engagement elements (13) thermally contact the coil wire (8) via the electrical insulation. Electric machine (1) according to one of the preceding claims, characterized in that the engagement elements (13) are designed in the form of shovels or pins. Electric machine (1) according to one of the preceding claims, characterized in that cooling channels (14) for passing a cooling fluid through are formed in the engagement elements (13). Electric machine (1) according to one of the preceding claims, characterized in that the cooling base body (12) of the cooling device (11) has a cooling plate (15) arranged at the end of the end winding (9), the cooling plate (15) extending from the end winding (9) having cooling ribs (16) extending away and / or a cooling fluid channel (14) for the passage of a cooling fluid. Electric machine (1) after Claim 8 , characterized in that an electronic component (17) of the electric machine (1) is arranged on the cooling plate (15). Motor vehicle (2), having a drive system (19), characterized in that the drive system (19) has an electric machine (1) according to one of the preceding claims.

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