BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to an electrical machine, specifically for a motor vehicle.

An electrical machine of this type, specifically for a motor vehicle, is already known, for example, from DE 10 2013 112 625 A1. The electrical machine comprises a stator, having at least one first magnet and at least one second magnet. The electrical machine further comprises a rotor, which is drivable by means of the stator, specifically by means of the magnets, and is thus rotatable about an axis of rotation relative to the stator.

The object of the invention is the further development of an electrical machine of the above-mentioned type, such that a particularly advantageous operation of the electrical machine can be achieved.

This object is fulfilled by an electrical machine according to the invention.

The electrical machine according to the invention, specifically for a motor vehicle such as, for example, a motor car, comprises a stator, which has at least one first magnet and at least one second magnet. The electrical machine further comprises a rotor, which is rotatable about an axis of rotation relative to the stator, which can be driven by means of the stator, specifically by means of the magnets, and is thus rotatable about the axis of rotation relative to the stator.

In order to permit the achievement of a particularly advantageous, and specifically an appropriate operation of the electrical machine, it is provided, according to the invention, that the first magnet is held on a first ring, and the second magnet is held on a second ring. The second ring follows the first ring, in the axial direction of the electrical machine. In other words, the rings, in the axial direction of the electrical machine, and thus along the axis of rotation, are arranged one after another, or sequentially. Accordingly, for example, the magnets are also arranged one after another, or sequentially, in the axial direction of the electrical machine. The second ring, together with the second magnet, is rotatable about the axis of rotation relative to the first ring and to the first magnet. In other words, the rings are rotatable relative to one another about the axis of rotation, such that—as the magnets are held or secured on the rings—the magnets are rotatable relative to one another about the axis of rotation. Thus, for example, a clearance between the magnets in the circumferential direction of the electrical machine can be appropriately set, such that a particularly advantageous, and specifically an efficient, effective and appropriate operation of the electrical machine is possible. Again, expressed in other words, the magnets are appropriately positionable relative to one another in the circumferential direction of the electrical machine, as a result of which, for example, a magnetic field creatable by the magnets, specifically the profile thereof, can be influenced in a particularly appropriate manner. As a consequence, an advantageous, efficient and effective operation of the electrical machine can be achieved.

The electrical machine preferably incorporates an actuator, by which the rings, and thus the magnets, are rotatable relative to one another about the axis of rotation. The actuator is preferably configured as an electrically-operatable actuator. Specifically, it is contemplated that at least one of the rings is rotatable about the axis of rotation relative to the rotor and/or relative to a housing, in which the stator and the rotor respectively are at least partially accommodated, whereas, for example, the other ring is non-rotational relative to the housing, and thus cannot be rotated about the axis of rotation relative to the housing. However, it has proved to be particularly advantageous if both rings are rotatable about the axis of rotation relative to the housing and relative to the rotor, as a result of which the magnets can be adjusted with respect to their position in a particularly appropriate manner.

The actuator comprises a first actuating element for example, by which the first ring is rotatable about the axis of rotation relative to the housing. Preferably, the actuator further comprises a second actuating element, by which, for example, the second ring is rotatable about the axis of rotation relative to the housing.

The electrical machine is preferably configured as an internal rotor machine, such that the rotor is at least partially arranged within the stator. The stator thus outwardly overlaps, for example, at least one longitudinal region of the rotor in the radial direction of the electrical machine, such that the magnets are configured, for example, as external magnets.

In an advantageous configuration of the invention, the magnets are respectively configured as electromagnets, as a result of which a particularly advantageous, and specifically an appropriate operation of the electrical machine can be achieved. Specifically, it is contemplated that the electrical machine is operable in a motor mode, and is thus operable as an electric motor. In the motor mode, the electrical machine delivers torques via the rotor, by which, for example, at least one wheel of the motor vehicle is drivable. Alternatively or additionally, the electrical machine can be operated, for example, in a generator mode, and can thus be operated as a generator. In the generator mode, the rotor is driven, for example by the kinetic energy of the moving vehicle such that, by way of the generator, kinetic or mechanical energy is converted into electrical energy, which is delivered by the generator.

It has proved to be particularly advantageous if the electromagnets are electrically actuatable in an individual or separate manner. It is thus possible, for example, for the electromagnets to be actuated independently of one another and/or in a different manner from one another such that, for example, a first electric voltage is applied to one of the electromagnets, and a second electric voltage, which differs from the first electric voltage, is applied to the other electromagnets, and/or such that an electric current of a first current strength flows in a first of the electromagnets, whereas electric current of a second current strength, which differs from the first current strength, flows in the second electromagnet. The electric voltages preferably differ from 0 and/or the electric current strengths differ from 0. Specifically, it is contemplated that one of the electric voltages or one of the electric current strengths differs from 0 whereas, for example, the other electric voltage or the other electric current strength assumes a value of 0. By means of the possibility for the appropriate positioning of the magnets, and for the appropriate or differing electrical actuation thereof, a particularly advantageous speed adjustment, and specifically a speed control of the rotor is possible, for example by means of the magnets which are configured as external magnets. Specifically, an intelligent control of the magnets and the fields thereof can be achieved. The respective field is, for example, a magnetic field created by the respective magnet, the flux of which can be adjusted in an appropriate manner. The number of magnets and the size thereof can be variable, and can be adjusted appropriately.

In a further embodiment of the invention, the electrical machine has at least a first operating state, in which the electromagnets are supplied with alternating current. A particularly advantageous operation can be achieved as a result.

A further embodiment is characterized in that the electrical machine has at least a second operating state, in which the electromagnets are supplied with direct current. Specifically, it is contemplated that, in the second operating state, the direct current flows through the electromagnets in a first direction. A third operating state is further contemplated, in which the electromagnets are supplied with direct current wherein, in a third operating state, the direct current flows through the electromagnets in a second direction, which is in opposition to the first direction. Overall, for example, an exceptionally rapid and advantageous acceleration of the rotor can thus be achieved. Moreover, by a corresponding electrical actuation of the magnets, the rotor can be braked in a particularly rapid, appropriate and targeted manner such that, for example, the overall braking of the vehicle can advantageously be achieved thereafter.

In a further configuration of the invention, a plurality of first magnets are held on the first ring, wherein a plurality of second magnets are held on the second ring. A particularly advantageous, effective and efficient operation of the electrical machine can be achieved as a result.

It has proved to be particularly advantageous if at least three first magnets, held on the first ring, and at least three second magnets, held on the second ring, are provided, wherein the first magnets and/or the second magnets are arranged with an equal mutual spacing in the circumferential direction of the respective ring. This means that pairs of the first or second magnets are arranged with an equal spacing from one another in the circumferential direction of the respective ring. If, for example, exactly three magnets are held on the respective ring, pairs of magnets are arranged with a respective clearance of 120 degrees running in the circumferential direction of the respective ring. In other words, for example, the magnets are arranged with a mutual offset of 120 degrees in relation to one another in the circumferential direction of the respective ring, as a result of which a particularly advantageous operation can be constituted.

In a further configuration of the invention, the rotor comprises at least one shaft which is rotatable about the axis of rotation relative to the stator, and a coil which is at least indirectly connected to the shaft, and is co-rotatable with said shaft, and which can be supplied with electric current. For example, the coil is at least indirectly non-rotationally connected to the shaft. Specifically, it is contemplated that the rotor comprises at least one carrier, which is also described as a carrier element. The carrier is, for example, non-rotationally connected to the shaft, and is thus co-rotatable with the shaft about the axis of rotation. The coil is at least indirectly, and specifically directly, held on the carrier here, for example. The coil, for example, is wound about at least one sub-region of the carrier.

It has proved to be particularly advantageous if the rotor is rotatably mounted on the stator by means of at least one rolling bearing device. The rolling bearing device has a first series of rolling elements, comprising a first rolling element ring with a plurality of first rolling elements arranged sequentially in the circumferential direction of the shaft, a second rolling element ring arranged subsequently to the first rolling element ring in an axial direction of the shaft, having a plurality of second rolling elements arranged sequentially in a circumferential direction of the shaft, and a first bearing ring element. The first bearing ring element forms a first raceway for the first rolling elements and a second raceway for the second rolling elements. This means that the rolling elements, which are configured in a mutually separate manner per se and arranged sequentially in the circumferential direction of the shaft, can roll or rotate in the respectively associated raceway.

The rolling bearing device further comprises a second series of rolling elements, comprising a third rolling element ring, which at least partially inwardly overlaps the first rolling element ring in the radial direction of the shaft, having a plurality of third rolling elements arranged sequentially in the circumferential direction of the shaft, a fourth rolling element ring arranged subsequently to the third rolling element ring in an axial direction of the shaft and at least partially inwardly overlapping the second rolling element ring in the radial direction of the shaft, having a plurality of fourth rolling elements arranged sequentially in a circumferential direction of the shaft, and a second bearing ring element arranged in the radial direction of the shaft between the first bearing ring element and the third rolling elements, and between the first bearing ring element and the fourth rolling elements. The second bearing ring element constitutes a third raceway for the third rolling elements, and a fourth raceway for the fourth rolling elements. As a result, the third rolling elements which are mutually separately configured and arranged sequentially in the circumferential direction of the shaft can roll in the third raceway, and the fourth rolling elements which are mutually separately configured and arranged sequentially in the circumferential direction of the shaft can roll in the fourth raceway, specifically when the shaft or the rotor as a whole is rotated about the axis of rotation, relative to the rotor.

The rolling bearing device further comprises at least one insulating element arranged in the radial direction between the series of rolling elements, specifically between the bearing ring elements, by means of which the series of rolling elements are electrically insulated from one another. In other words, the first series of rolling elements is electrically insulated from the second series of rolling elements by means of the insulating element. Moreover, in at least one operating state of the electrical machine, the coil, also described as the winding, is supplied with electric current such that said electric current flows to the coil via one of the series of rolling elements, and flows from the coil via the other series of rolling elements.

The electric current with which the coil is supplied is delivered, for example, by an energy or current source. In the above-mentioned operating state, electric current delivered by the current source flows, for example, from the current source via the one series of rolling elements to the coil, and through said coil. Thereafter, for example, the electric current flows out of the coil, and here from the coil via the other series of rolling elements to the current source, or to the ground of the electrical machines as a result of which, for example, an electric circuit is closed. Specifically, it is contemplated that the infeed of electric current, for example to the coil, is delivered via the above-mentioned carrier and/or that electric current flows out of the coil via the carrier.

By means of this supply of electric current to the coil, a particularly simple, space-saving, weight-saving, efficient and effective electric current supply is ensured, such that a particularly advantageous operation of the electrical machine can be achieved.

In order to achieve the supply of electric current to the coil in a particularly advantageous manner, and thus permit the achievement of a particularly advantageous operation of the electrical machine, in a further embodiment of the invention, it is provided that the first rolling element ring and the third rolling element ring are arranged in a first longitudinal region of the rolling bearing device, wherein the first longitudinal region is configured in an overlap-free outward arrangement, in the radial direction, to the coil and/or to the carrier which is non-rotationally connected to the shaft, on which the coil is mounted. Thus, the first rolling element ring and the second rolling element ring, in the outward radial direction, are not overlapped by the coil or by the carrier.

The second rolling element ring and the fourth rolling element ring, for example, are arranged in a second longitudinal region of the rolling bearing device, which is arranged in an axial direction of the shaft subsequently to the first longitudinal region, wherein the second longitudinal region, in the outward radial direction, is overlapped by the coil and/or by the carrier.

In order to achieve a particularly advantageous electric current supply, it is provided, in a further configuration of the invention, that the rotor is rotatably mounted on the stator by means of at least one second rolling bearing device, arranged in the axial direction of the shaft subsequently to the rolling bearing device and spaced from said rolling bearing device. The second rolling bearing device comprises a third series of rolling elements, having a fifth rolling element ring with a plurality of fifth rolling elements which are arranged sequentially in a circumferential direction of the shaft, wherein, in the at least one operating state of the electrical machine, the coil is supplied with electric current in such a way that the electric current flows to or from the coil via the third series of rolling elements.

Finally, it has proved to be particularly advantageous if, in at least one operating state of the electrical machine, the coil is supplied with electric current in such a way that the electric current flows to or from the coil via the shaft. Thus, at least one longitudinal region of the shaft is also employed for the supply of electric current to the shaft, thus permitting a particular restriction of the number of parts, the weight and the space requirement. As a consequence, a particularly advantageous, and specifically an effective and efficient operation of the electrical machine can be constituted.

Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.

