Rotor shaft portion, electric motor drive unit, and vehicle

Abstract

The invention proposes a rotor shaft portion (2) for an externally excited synchronous machine of an electric motor drive unit, in particular for driving a vehicle. The rotor shaft portion (2) is partly produced from a plastic in which metal contacting means for externally exciting the synchronous machine are embedded. These contacting means comprise at least two slip rings (10, 12) for contacting with an associated brush (24, 26), and at least one conductor track (16, 18) for each slip ring (10, 12), the respective conductor track (16, 18) extending from the associated slip ring (10, 12) through the plastic of the rotor shaft portion (2). At least one rib portion (R1, R2, R3, R4) which protrudes radially and / or axially - with respect to a rotation axis of the rotor shaft portion (2) - is integrally formed on at least one of the two slip rings (10, 12) in order to increase a slip ring surface area. The invention additionally proposes an electric motor drive unit comprising such a rotor shaft portion, and a vehicle comprising such an electric motor drive unit.

Description

[0001] Description

[0002] Rotor shaft section, electric motor drive unit and vehicle

[0003] The invention relates to a rotor shaft section for a separately excited synchronous machine of an electric motor drive unit, in particular for driving a vehicle, an electric motor drive unit, in particular for driving a vehicle, having such a rotor shaft section and a vehicle having such an electric motor drive unit.

[0004] One object underlying the invention is to improve an electric motor drive unit, in particular for driving a vehicle.

[0005] This object is achieved by a rotor shaft section proposed and protected according to claim 1.

[0006] The proposed rotor shaft section is intended in particular for use with a wet-running brush actuator or brush controller for power transmission, the brushes of which are oiled during operation of a separately excited synchronous machine or come into contact with an oil provided or stored for the lubrication and cooling of the synchronous machine or are wetted with this oil.

[0007] Heat is generated at the respective contact surfaces or contact points between the grinding brushes and the associated slip rings due to friction losses as well as ohmic or electrical losses, whereby these losses as such vary depending on the operating point of the synchronous machine.

[0008] Particularly when the synchronous machine is at a standstill or at low speeds, heat dissipation or heat removal through the oil is poor or insufficient. At low speeds of the synchronous machine, which are associated with high torques, high currents or rotor currents are transmitted across the contact surfaces, resulting in correspondingly high ohmic or electrical losses at the contact surfaces or contact points. This can lead to excessively high slip ring and brush temperatures, which can damage or age the oil and thus have a lasting negative impact.

[0009] The at least one rib section proposed or provided to enlarge the slip ring surface contributes to significantly reducing these high slip ring and brush temperatures, particularly at low speeds of a rotor shaft or such a synchronous machine.

[0010] Such a proposed rib section thus counteracts or at least slows down temperature-related oil aging.

[0011] Particularly in conjunction with lubrication of the proposed rotor shaft section, these slip ring and brush temperatures can be further reduced. Consequently, thermal stress on the slip rings and brushes can also be advantageously reduced.

[0012] The lubrication can be actively implemented by supplying an oil intended for lubrication and cooling of the synchronous machine, for example by means of a spray nozzle, to the rotor shaft section in an area of ​​the slip rings and grinding brushes or the respective contact surfaces.

[0013] In addition, or alternatively, or in the simplest case, it can also be ensured by design that, during operation of the synchronous machine or the vehicle, the oil can penetrate into this area of ​​the slip rings and brushes and thus wet them. In this context, one can also speak of passive lubrication.

[0014] And by reducing the thermal stress on a brush actuator or brush controller having such grinding brushes, such an actuator or controller can also be made smaller and thus more space-saving. The orientation or extension of such a rib section is to be understood in a longitudinal direction and / or transverse direction of a rotor shaft (section) axis or a rotational axis of such a rotor shaft section. This means that the rib section formed on at least one of the two slip rings can be designed in any desired manner - with respect to such an axis, i.e. projecting radially outwards and / or inwards - i.e. away from the axis and / or towards the axis - and / or projecting axially in order to enlarge the slip ring surface for the purpose of improved heat dissipation or improved heat removal.

[0015] In one embodiment, it is proposed that at least two such rib sections, which are spaced apart from one another and each project radially and / or axially, are provided per slip ring, wherein two adjacent rib sections of an associated slip ring are spaced apart from one another in such a way that they enable contact with the associated grinding brush.

[0016] In a further embodiment, it is proposed that one of the two slip rings is also formed with a front-side, metallic section with interruptions in the circumferential direction of the rotor shaft section, wherein this front-side metallic section is designed to interact with an associated signal transmitter for detecting the position of a rotor of the synchronous machine.

[0017] The separate excitation of the synchronous machine, on the one hand, and the position detection of the synchronous machine's rotor, on the other, are made possible by the proposed slip ring, which, as such, implements both of these functions. The proposed rotor shaft section thus contributes to a reduction in the number of components. This, in turn, results in savings in weight, installation space, and costs. It also simplifies rotor shaft assembly.

[0018] In this case, the slip ring with the front-side metallic section can be designed as a pot-shaped element, wherein the bottom of the pot forms the said front-side metallic section with the interruptions in the circumferential direction of the rotor shaft section.

[0019] In a further embodiment, it is proposed to design the rotor shaft section in the form of a rotor shaft attachment, the plastic of which is injection-molded onto a metallic sleeve that can be pushed onto a shaft journal of a rotor shaft.

[0020] Alternatively, the plastic of the rotor shaft section can also be injection-molded directly onto such a shaft journal of a rotor shaft, so that the proposed rotor shaft section is to be understood as a part formed or molded in one piece with the rotor shaft.

[0021] Furthermore, an electric motor drive unit, in particular for driving a vehicle, is proposed and protected. The electric motor drive unit comprises a separately excited synchronous machine with a rotor shaft section of the type described above (see claim 7).

[0022] In addition, a vehicle with an electric motor drive unit of this type is proposed and protected (see claim 8).

[0023] A vehicle is understood to mean any type of vehicle or motor vehicle that is powered by an electric motor, but in particular, passenger cars and / or commercial vehicles in the form of an electric or hybrid vehicle. These are preferably semi-autonomous and, in particular, fully autonomous vehicles. The invention is explained in detail below with reference to figures. Further advantageous developments of the invention emerge from the dependent claims and the following description of preferred embodiments. In this regard, the following figures show:

[0024] Fig. 1 shows a proposed rotor shaft section in a sectional view and

[0025] Fig. 2 shows the rotor shaft section shown in Fig. 1 in a perspective view.

[0026] The rotor shaft section 2 shown in Fig. 1 is part of a rotor shaft of a separately excited synchronous machine, particularly for driving a vehicle. Fig. 1 also shows this rotor shaft section 2 in conjunction with a brush actuator or

[0027] Brush actuator, whose grinding brushes 24, 26 are applied against associated slip rings 10, 12 of the rotor shaft section 2.

[0028] Fig. 1 shows a metallic shaft end or a shaft journal 4, to which a plastic or a plastic section 6 is attached.

[0029] This plastic section 6 can be injection-molded directly onto the shaft journal 4 and thus be integrally connected thereto. Alternatively, this plastic section 6 can also be injection-molded onto a sleeve (not shown in Fig. 1) and thus integrally connected thereto, which, as such, can be pushed onto the shaft journal 4 in a form-fitting and / or force-fitting or friction-fitting manner and can, for example, form a press fit with the shaft journal 4. In the latter case, or in the case of the sleeve, the proposed rotor shaft section 2 thus forms a type of rotor shaft adapter (part) or rotor shaft attachment.

[0030] Embedded in this plastic section 6 are metallic contacting means in the form of two slip rings 10, 12 and two conductor tracks 16, 18, which are contacted with an associated slip ring 10, 12 and extend from the associated slip ring 10, 12 through the plastic section 6 in the direction of an externally excited rotor (not shown here) arranged on the rotor shaft.

[0031] Between the slip rings 10, 12, a radially projecting plastic section 8 is provided, which is formed in one piece or integrally with the plastic section 6. This plastic section 8 serves to adequately insulate the two slip rings 10, 12 from one another, specifically in the form of so-called air gaps and creepage gaps to protect against short circuits. Likewise, a brush actuator or brush control section made of a plastic, into which the plastic section 8 extends, provides adequate insulation between the two brushes 24, 26 from one another, specifically in the form of so-called air gaps and creepage gaps to protect against short circuits. This brush actuator or brush control section and the plastic section 8 thus form a type of insulation structure in the illustrated assembly to protect against short circuits.

[0032] For each slip ring 10, 12, two spaced-apart, radially projecting rib sections Ri, R2, R3, R4 are provided. The rib sections Ri, R2, R3, R4 of an associated slip ring 10, 12 are formed or configured at such a distance from one another that they enable contact with the associated brush 24, 26 and thereby flank the associated brush 24, 26.

[0033] The slip ring 12 is shaped or formed in a pot-like manner. The base of the pot forms a front section 14 of one end of the rotor shaft section 2, in order to be able to interact with, for example, an inductive signal transmitter of a circuit board for detecting the position of the rotor shaft and thus of the rotor.

[0034] Fig. 2 shows the rotor shaft section 2, but detached from the rotor shaft journal 4 and the brush arrangement according to Fig. 1. Fig. 2 also shows the design of the metallic section 14 with its interruptions U in the circumferential direction of the slip ring 12, which as such can be completely filled with the injection-molded plastic. Between two adjacent interruptions U or recesses of this type is a metallic web-shaped section 20, which as such extends radially inward or in the direction of the rotational axis of the rotor shaft section.

[0035] The blind hole in the shaft journal 4 shown in Fig. 1 has no significance within the scope of the invention proposed or disclosed here. Rather, it is a receiving point for the rotor shaft, enabling the rotor shaft to be balanced.

[0036] The proposed rotor shaft section 2 implements at least two, i.e., strictly speaking, even three functions:

[0037] It serves, on the one hand, to separately excite the rotor of the rotor shaft and, on the other hand, to detect the position of the separately excited rotor. The slip ring 12 implements these two functions in a single component. On the one hand, it acts as a contact element with the grinding brush 12, and on the other hand, it acts as a sensor wheel with the signal generator.

[0038] When interacting with the signal generator, periodic or sine-cosine voltage signals are generated, from which an absolute angular position of the rotor relative to a stator of the synchronous machine can be determined in a control unit, allowing the synchronous machine to be commutated efficiently. Therefore, the rotor shaft section 2 shown in Fig. 1 represents at least a so-called 2-in-1 module (implementation of two functions in one module or in the rotor shaft section 2).

[0039] In addition, there is an improved thermal behavior of such a rotor shaft section 2 - already described at the beginning - due to the proposed rib sections Ri, R2, R3, R4 in conjunction with a brush actuator or brush actuator which interacts with the rotor shaft section 2.

[0040] And if one considers this improved thermal behavior as a further feature of the rotor shaft section 2, then one can even speak of a 3-in-1 module (- implementation of three functions in one module or in the rotor shaft section 2).

[0041] The proposed rotor shaft section 2 is intended in particular for use with a wet-running brush actuator or brush controller. Reference is made here, for example, to German patent application DE 10 2023 110 338.5, which discloses a wet-running arrangement of a rotor shaft section and a brush controller or brush controller. The controller or brush controller

[0042] The actuator enables the grinding brushes to be pressed against the assigned slip rings as required. Depending on the requirements, the grinding brushes can be pressed against the slip rings either passively or actively using spring preload.

[0043] Although exemplary embodiments are explained in the foregoing description, it should be noted that numerous modifications are possible. Furthermore, it should be noted that the exemplary embodiments are merely examples and are not intended to limit the scope of protection, applications, or structure in any way. Rather, the foregoing description provides the skilled person with a guide for implementing at least one exemplary embodiment, whereby various modifications, particularly with regard to the function and arrangement of the described components, can be made without departing from the scope of protection as it results from the claims and equivalent combinations of features.

Claims

Patent claims 1. Rotor shaft section (2) for a separately excited synchronous machine of an electric motor drive unit, in particular for driving a vehicle, wherein the rotor shaft section (2) is made in sections from a plastic material in which metallic contacting means for separately exciting the synchronous machine are embedded, wherein these contacting means comprise at least two slip rings (10, 12) for contacting an associated slip brush (24, 26) and at least one conductor track (16, 18) per slip ring (10, 12), wherein the respective conductor track (16, 18) extends from the associated slip ring (10, 12) through the plastic material of the rotor shaft section (2), wherein at least one of the two slip rings (10, 12) has at least one radially and / or axially projecting rib section (Ri, R2, R3, R4) formed thereon for enlarging a slip ring surface, relative to a rotational axis of the rotor shaft section (2).

2. Rotor shaft section (2) according to claim 1, wherein at least two spaced-apart, radially and / or axially projecting rib sections (Ri, R2, R3, R4) are provided for each slip ring (10, 12), wherein two adjacent rib sections (Ri, R2, R3, R4) of an associated slip ring (10, 12) are spaced from one another in such a way that they enable contact with the associated grinding brush (24, 26).

3. Rotor shaft section (2) according to claim 1 or 2, wherein one of the two slip rings is further formed with a front-side, metallic section (14) with interruptions (U) in the circumferential direction of the rotor shaft section (2), wherein this front-side metallic section (14) is designed to cooperate with an associated signal transmitter for detecting the position of a rotor of the synchronous machine.

4. Rotor shaft section (2) according to one of the preceding claims, wherein the slip ring (12) with the front-side metallic section (14) is designed as a pot-shaped element.

5. Rotor shaft section (2) according to one of the preceding claims, which is designed in the form of a rotor shaft attachment, the plastic of which is sprayed onto a metallic sleeve which can be pushed onto a shaft journal of a rotor shaft (4).

6. Rotor shaft section (2) according to one of the preceding claims 1 to 4, the plastic of which is injection-molded onto a shaft journal of a rotor shaft (4).

7. Electric motor drive unit, in particular for driving a vehicle, with a separately excited synchronous machine with a rotor shaft section according to one of the preceding claims 1 to 6.

8. Vehicle with an electric motor drive unit according to claim 7.

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