ELECTRIC MACHINE AND MOTOR VEHICLE

An electric machine includes a housing, a rotor including a rotor shaft and a rotor laminated core, and a stator including a stator laminated core with grooves in which stator windings are received, through which a coolant can flow, and wherein a respective tooth of the stator laminated core is arranged between two respective grooves arranged adjacent to one another in a circumferential direction. An annular gap is included between the rotor and stator laminated cores and a tooth head ring arranged in the annular gap, a respective recess of the tooth head ring arranged between two tooth heads of the tooth head ring arranged adjacent to one another in a circumferential direction of the tooth head ring. A wall element is arranged in the annular gap and seals the stator against the rotor such that, from the stator via the annular gap, no coolant moves towards the rotor.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit to German Patent Application No. DE 10 2022 125 595.6, filed on Oct. 5, 2022, which is hereby incorporated by reference herein.

FIELD

The invention relates to an electric machine. The invention further relates to a motor vehicle.

BACKGROUND

The basic design of an electric machine is known from practice. An electric machine has a housing and a stator, which comprises a stator laminated core. The stator is also referred to as the stand. An electric machine also has a rotor, which comprises a rotor shaft and a rotor laminated core. The rotor is also referred to as the runner. The rotor is rotatably mounted in the housing.

DE 10 2019 106 801 A1 and DE 10 2020 117 274 B3 each disclose electric machines having a stator and a rotor. It is disclosed that the stator comprises a stator laminated core, wherein grooves are introduced into the stator lamination, in which stator windings are accommodated. The grooves of the stator laminated core are open radially inwardly, facing the rotor. An annular gap is formed between the rotor and the stator.

In order to be able to operate an electric machine efficiently with a high performance coefficient, a cooling, in particular of the stator windings of the stator, is advantageous. DE 10 2017 102 141 A1 discloses an electric machine around whose stator windings coolant directly flows. The coolant flows through the grooves of the stator laminated core, in which the stator windings are received. In order to prevent the coolant from flowing from the stator into the region of the rotor, a sealing means configured as a sleeve-like wall element is arranged in the annular gap between the stator and the rotor. Such a sleeve-like sealing means is also referred to as a liner or a collimator.

SUMMARY

In an embodiment, the present disclosure provides an electric machine, comprising a housing, a rotor comprising a rotor shaft and a rotor laminated core, and a stator comprising a stator laminated core, wherein the stator laminated core comprises grooves in which stator windings are received, through which a coolant can flow, and wherein a respective tooth of the stator laminated core is arranged between two respective grooves that are arranged adjacent to one another in a circumferential direction. The electric machine further comprises an annular gap formed between the rotor laminated core and the stator laminated core and a tooth head ring arranged in the annular gap, a respective recess of the tooth head ring being arranged between two tooth heads of the tooth head ring that are arranged adjacent to one another in a circumferential direction of the tooth head ring. The electric machine further comprises a wall element arranged in the annular gap between the tooth head ring and the stator laminated core, wherein the wall element seals the stator against the rotor such that, proceeding from the stator via the annular gap and the tooth head ring, no coolant moves towards the rotor.

DETAILED DESCRIPTION

There is a need for an electric machine that can be operated efficiently and thus with a high performance coefficient, which preferably serves as a drivetrain assembly of a motor vehicle. The problem addressed by embodiments of the invention create a corresponding electric machine and a motor vehicle.

According to an embodiment of the invention, a tooth head ring is arranged in the annular gap, a respective recess of the tooth head ring is arranged between two tooth heads that are arranged adjacent to one another in the circumferential direction of the tooth head ring.

According to an embodiment of the invention, a wall element is further arranged in the annular gap, namely between the tooth head ring and the stator laminated core, wherein the wall element seals the stator against the rotor such that, proceeding from the stator via the annular gap and the tooth head ring, no coolant moves towards the rotor.

Via the tooth head ring arranged in the annular gap of the electric machine and arranged between the sleeve-like wall element and the rotor, the sleeve-like wall element can be radially supported inwardly. There is then no risk that the latter will undesirably deform as a result of a coolant pressure and that coolant will leak in the direction of the rotor.

Furthermore, the magnetic flux can be optimally guided using the tooth head ring arranged in the annular gap of the electric machine in order to minimize losses in the stator. As a result, it is ultimately possible to operate an electric machine efficiently and thus with a high performance coefficient.

Preferably, via a relative movement between the stator laminated core of the electric machine and the tooth head ring of the electric machine, the relative position of the stator laminated core and the tooth head ring is adjustable such that, in a first relative position of the stator laminated core and the tooth head ring, the tooth heads of the tooth head ring radially inwardly abut the teeth of the stator laminated core, and, in a second relative position of the stator laminated core and the tooth head ring, the tooth heads radially inwardly abut the grooves of the stator laminated core, in each case having a wall element positioned therebetween. Then, when the relative position of the stator laminated core and the tooth head ring is adjustable, a particularly efficient operation of the electric machine at different operating points and load conditions of the electric machine is possible.

The first relative position of the stator laminated core and the tooth head ring of the electric machine is used in particular for a full-load operation of the electric machine in order to allow for the greatest possible electromagnetic flux, so that the electric machine can provide a maximum torque.

The second relative position of the stator laminated core and the tooth head ring of the electric machine is used in particular for a partial-load operation of the electric machine in order to reduce the direction of the electromagnetic flux and to reduce losses, in particular so-called intrinsic losses, in the stator and thus also to enable efficient operation with a high performance coefficient in the partial-load operation.

Preferably, the electric machine comprises an actuator configured so as to transition the stator laminated core or tooth head ring from the first relative position into the second relative position and from the second relative position into the first relative position. The relative position between the stator laminated core and the tooth head ring of the electric machine can be particularly advantageously changed or adjusted via an actuator of the electric machine.

According to a first embodiment of the invention, the wall element is configured so as to be fixed in place, as is the stator laminated core and the housing, wherein the tooth head ring is configured so as to be rotatable relative to the stator laminated core and relative to the wall element in the circumferential direction of the tooth head ring. According to a second embodiment of the invention, the wall element is configured so as to be fixed in place, as is the tooth head ring and the housing, wherein the stator laminated core is configured so as to be rotatable relative to the tooth head ring and relative to the wall element in the circumferential direction of the stator laminated core. In both embodiments, the wall element, as well as the housing, is configured so as to be fixed in place and sealed against the housing. In the first embodiment of the invention, the tooth head ring is rotatable relative to the fixed stator laminated core and, in the second embodiment of the invention, the stator laminated core is rotatable in a circumferential direction relative to the fixed tooth head ring in order to adjust the relative position between the stator laminated core and the tooth head ring of the electric machine. Both embodiments allow for an efficient operation of an electric machine with a high performance coefficient.

Preferably, in the second embodiment of the invention, the wall element is applied radially outwardly onto the tooth head ring and fixedly connected thereto. In the second embodiment of the invention, the wall element can be fixedly connected to the tooth head ring and can thus be integrated into the tooth head ring. In this case, there is then no gap between the tooth head ring and the wall element, so that the tooth head ring can optimally support the wall element.

In the first embodiment of the invention, a small air gap is formed between the tooth head ring and the wall element in order to be able to displace the tooth head ring relative to the wall element. In this embodiment, however, the tooth head ring can also protect the wall element against impermissibly high deformation by radially inner support.

A motor vehicle according to an embodiment of the invention is provided.

Embodiments of the invention emerge from the following description. Without being restricted thereto, embodiments of the invention will be explained in greater detail with reference to the drawings.

FIGS.1and2show different views of an electric machine10according to an embodiment of the present invention. The electric machine10has a housing11, a stator12, and a rotor13. The stator12is also referred to as the stand, and the rotor13is also referred to as the runner.

The rotor13is rotatably supported in the housing11via bearings14. Thus,FIG.2shows a rotor shaft15that is rotatably supported in the housing11via the bearings14. The rotor shaft15supports a rotor laminated core16.

The stator12comprises a stator laminated core17. Grooves18are introduced into the stator laminated core17, wherein stator windings19are arranged in the grooves18of the stator laminated core17. The stator windings19project from the stator laminated core12at axial ends of the stator laminated core12and form winding heads20there.

The grooves18of the stator laminated core12are perfused by coolant such that the stator windings19received in the grooves18are directly surrounded by coolant. The winding heads20are also directly surrounded by coolant. InFIG.2, a coolant inlet21and a coolant outlet22of the housing11are shown, via which coolant can be supplied for cooling of the stator12and then discharged.

Between circumferentially adjacent grooves18of the stator laminated core17, the stator laminated core17forms teeth23. Between two circumferentially adjacent teeth23, a respective groove18is configured so as to receive the stator windings19, around which coolant directly flows.

An annular gap24is formed between the stator12and the rotor13of the electric machine10, namely between the stator laminated core12and the rotor laminated core16. A tooth head ring25is arranged in the annular gap24.

The head ring25has a plurality of tooth heads26arranged side-by-side in the circumferential direction of the head ring, wherein a recess27of the tooth head ring25is formed between two respective circumferentially distanced tooth heads26of the head ring25. In the region of these recesses27, the tooth heads26are connected to one another by webs28.

In the exemplary embodiment shown, the recesses27of the tooth head ring25are open radially outwardly towards the stator laminated core17. The webs28thereof, which connect the tooth heads26, are then positioned radially inwardly. By contrast, it is also possible for the recesses27of the tooth head ring25to open radially inwardly towards the rotor laminated core16, in which case the webs28would then be arranged radially outwards for connecting the tooth heads26.

In the annular gap24, not only the tooth head ring25is arranged, but rather also a wall element29. This wall element29is arranged between the tooth head ring25and the stator laminated core17of the stator12and is preferably shaped like a sleeve in the form of a liner or also a collimator. The wall element29seals the stator12against the rotor13and ensures that no coolant moves towards the rotor13proceeding from the stator12via the annular gap24and via the tooth head ring25. The wall element29therefore seals the rotor13against the stator12in order to prevent coolant from entering the region of the rotor13.

Via the tooth head ring25, the magnetic flux can be optimally guided during operation of the electric machine10in order to efficiently operate the electric machine10with a high performance coefficient. Furthermore, the tooth head ring25can support the wall element29radially inwardly and can prevent an impermissibly large deformation of the wall element29. Leaks in the wall element29can thus be prevented. Overall, it is possible to efficiently operate an electric machine10with a high performance coefficient.

According to an advantageous embodiment of the invention, via a relative movement between the stator laminated core17and the tooth head ring25, the relative position of the stator laminated core17and the tooth head ring25is adjustable such that, in a first relative position of the stator laminated core17and the tooth head ring25, the tooth heads26of the tooth head ring25radially inwardly abut the teeth23of the stator laminated core17, namely with the wall element29positioned therebetween. This relative position is shown inFIG.1. By means of a relative movement between the stator laminated core17and the tooth head ring25in the circumferential direction of the stator laminated core17and thus the tooth head ring25, a second relative position of the stator laminated core17and the tooth head ring25can also be adjusted, in which the tooth heads26radially inwardly abut the grooves18of the stator laminated core17and thus the stator windings19received in the grooves18, namely with the wall element29positioned therebetween.

The first relative position of the stator laminated core17and the tooth head ring25is particularly advantageous for full-load operation of the electric machine10in order to provide a maximum magnetic flux so that the electric machine can ultimately generate a maximum torque. The second relative position of the stator laminated core17and the tooth head ring25is particularly advantageous for partial-load operation in order to adjust an air gap with higher efficiency, thereby reducing the guidance of the magnetic flux and reducing losses, in particular intrinsic losses, in the stator12in the partial-load operation. Finally, an electric machine10can be efficiently operated with a high performance coefficient both in full-load operation and in partial-load operation.

In the exemplary embodiment ofFIGS.1and2, the wall element29as well as the stator laminated core17and the housing11are configured so as to be fixed in place. The tooth head ring25can be rotated relative to the stator laminated core17and relative to the wall element29in the circumferential direction of the tooth head ring25in order to change the relative position between the tooth head ring25and the stator laminated core17. For example,FIG.2shows bearings29via which the tooth head ring25is rotatably supported in the housing11of the electric machine10.

An actuator30is used in order to rotate the tooth head ring25in the circumferential direction thereof. This actuator30can be an actuator that actively twists the tooth head ring25in the circumferential direction in relation to the stator laminated core12in order to transfer the latter from the first relative position into the second relative position and vice versa from the second relative position into the first relative position.

In the exemplary embodiment ofFIGS.1and2, a small gap is formed between the tooth head ring25and the wall element29, so that the tooth head ring25can freely rotate without contact to the wall element29.

If, however, the wall element29is subjected to deformation as a result of impermissibly high coolant pressures, the tooth head ring25can radially inwardly support the wall element and protect it against impermissibly large deformation.

The wall element29, which can be configured as a liner or a collimator, is sealed against the housing11. For example,FIG.2shows that sealing elements31are arranged at axial ends of the wall element29between the housing11and the wall element29.

FIGS.3,4, and5show details of a second exemplary embodiment of an electric machine10, wherein the same reference numerals are used for the same assemblies in order to avoid unnecessary repetitions, and reference is made to the embodiments of the exemplary embodiment ofFIGS.1and2. The only detailed descriptions below will be for aspects in which the electric machine10ofFIGS.3to5differs from the electric machine10ofFIGS.1and2.

While inFIGS.1,2, the stator12is fixed and the tooth head ring25is configured so as to be rotatable in the circumferential direction, in the exemplary embodiment ofFIGS.3to5it is provided that the tooth head ring25is fixed and the stator laminated core17is rotatable in the circumferential direction relative to the stator laminated core12in order to adjust the relative position between the stator laminated core17and the tooth head ring25. For this purpose, the stator12, namely the stator laminated core17, is rotatably supported in the housing11of the electric machine10via a bearing32, wherein the rotation of the stator laminated core12in the circumferential direction thereof is in turn provided by an actuator30. Accordingly, in the exemplary embodiment ofFIGS.3,4, and5, the wall element29as well as the tooth head ring25and the housing11are configured so as to be fixed in place, and the stator laminated core17is configured so as to be rotatable relative to the tooth head ring25and relative to the wall element29in the circumferential direction of the stator laminated core17.

InFIG.3, the actuator30comprises spring elements33configured as resetting elements that automatically push the stator laminated core17of the stator12into a relative position. From this relative position, the stator laminated core17can then be transferred to the respective other relative position in the circumferential direction of the latter counter to the resetting force of the resetting elements, in particular counter to the spring force of the spring elements.

Preferably, the spring elements33push the stator laminated core17into the second relative position. In this second relative position, the tooth heads26of the tooth head ring25radially abut the grooves18or the stator windings19of the stator12received in the grooves18, namely with the wall element29positioned therebetween. Out of this second relative position, the stator laminated core17of the stator12can be transferred to the first relative position counter to the spring forces of the spring elements33, namely either actively via an actuator or passively by exploiting electromagnetic forces that build up during operation of the electric machine or torques of the electric machine10to be supported.

For example, the spring elements33can be sized such that they automatically push the stator laminated core17into the second relative position, up to a certain threshold value. If the torque supplied and to be supported by the electric machine is greater than the determined threshold value, the stator laminated core17is automatically transferred into the first relative position, counter to the spring forces of the spring elements33. A hysteresis can be adjusted via friction elements for a spring characteristic curve of the spring elements33in order to avoid a frequent transfer back and forth between the first relative position and the second relative position.

Also in the exemplary embodiment ofFIGS.3,4, and5, the wall element29is arranged between the tooth head ring25and the stator laminated core17in the annular gap24between the stator laminated core17and the rotor laminated core16, wherein, however, in the exemplary embodiment ofFIGS.3,4, and5, no air gap is required between the wall element29and the tooth head ring25.

Rather, in the exemplary embodiment ofFIGS.3,4, and5, it is provided that the wall element29is directly applied radially outwardly on the tooth head ring25and is fixedly connected thereto. As can in particular be seen inFIGS.3and4, projections34of the wall element29extend into the recesses27of the tooth head ring25. The tooth head ring25and wall element29thus form an integral assembly.

The tooth head ring25is preferably made from a laminated core of electric sheets and accordingly made of a metallic material. The wall element29is made of a plastic, for example a fiber-reinforced plastic.

Also in the exemplary embodiment ofFIGS.3,4, and5, it is possible that, by contrast to the exemplary embodiment shown, the recesses27of the tooth head ring25do not open radially outwards but rather radially inwards. In this case, however, the wall element29radially outwardly abuts the tooth head ring25.

The electric machine10according to an embodiment of the invention uses a direct cooling of the stator windings19received in the grooves18of the stator laminated core17as well as the winding heads20, which are formed on both sides of the stator laminated core17. Heat can thus be optimally dissipated from the stator windings19. The wall element29prevents the coolant from entering the region of the rotor13.

Between the rotor13and the wall element29, i.e., radially inwardly abutting the wall element29, the tooth head ring25is positioned, which can protect the wall element29against impermissibly large deformations and via which the magnetic flux can be optimally guided in the operation of the electric machine.

In particular, via a change in the relative position between the tooth head ring25and the stator laminated core17, the magnetic flux can be optimally adjusted to the load point of the electric machine10in order to minimize losses and increase the efficiency and thus the performance coefficient of the electric machine.

In the exemplary embodiments shown, magnets35are arranged in recesses of the rotor laminated core16. In the case of a permanently stimulated synchronous machine, the magnets35are permanent magnets. However, in the recesses of the rotor laminated core16of the rotor13, geometries generating a reluctance, rotor windings, or short-circuited cages made of copper or aluminum can also be provided in other designs.