Radial flux rotor machine and its use, as well as wheel hub drive

Abstract

Radial flux rotor machine for a wheel hub drive (1) with a drum brake (20), with a stator (14) with a stator core (16); with a rotor (11) associated with the stator core (16); with a bearing shield (15) supporting the stator core (16); with a brake drum (20) arranged radially inside the rotor (11) and fixed on a wheel hub (17); with a brake unit (21) mounted in the brake drum (20); and with a parking brake actuator (28) operatively connected to the brake unit (21), wherein the brake unit (21) is arranged directly on a first surface (29) of the bearing shield (15) facing the stator core (16) and the parking brake actuator (28) is arranged on a second surface (30) of the bearing shield (15) facing away from the first.

Description

AREA OF INVENTION

[0001] The present invention relates to a radial flux rotor machine for a wheel hub drive with a drum brake. The invention further relates to the use of a drum brake in a radial flux rotor machine for a wheel hub drive and a wheel hub drive. TECHNICAL BACKGROUND

[0002] Electric machines with a stator and up to two rotationally fixed rotors, so-called radial flux rotor machines or radial flux double rotor machines (also referred to simply as double rotor, multiple rotor, or dual rotor), are suitable for increasing both the torque density and the efficiency of electric drives compared to conventional electric machines. Particularly in wheel hub drives, such radial flux rotor machines offer decisive advantages in terms of achievable efficiency and the required installation space in the vehicle.

[0003] An example of a radial flux twin-rotor motor is described in DE 10 2021 003 942 A1. These types of radial flux twin-rotor motors are characterized by high torque and power density. Radial flux twin-rotor motors generally employ established and mass-producible manufacturing processes for the winding and stator core, enabling the support of the torque generated in the stator core. Radial flux rotor motors used as wheel hub motors regularly employ drum brakes as an alternative to conventional disc brakes, resulting in a more compact and robust design. The drum brake unit and a parking brake actuator are typically mounted on a carrier plate, which is then integrated into the radial flux rotor motor between a stator end plate or a winding head carrier and the rotor.This configuration generally requires a relatively large opening in the stator end shield to allow mounting the parking brake actuator to the drum brake unit's support shield. This reduces the stiffness of the end shield and also necessitates the integration of additional radial sealing elements for the openings into the system.

[0004] DE 10 2011 081 503 A1 discloses a wheel hub drive system with an electric motor arranged within a rim. The electric motor is designed to be operated with direct current, with alternating current being generated by an inverter attached to the stator. DE 10 2012 204 790 A1 shows a drive system for vehicles, in particular wheel hub drive systems, which includes a thermal shielding device and a dynamic brake compartment seal. DE 10 2011 081 118 A1 describes a drive system, in particular for electric and hybrid vehicles, which includes a rotor carrier made of a light metal such as aluminum, which is held between a rim contact plate and a wheel flange. SUMMARY OF THE INVENTION

[0005] Against this background, the present invention aims to provide an improved radial flux twin-rotor machine which in particular has reduced assembly effort and improved stiffness of the bearing shield.

[0006] According to the invention, this problem is solved by a radial flux rotor machine with the features of claim 1 by using it in conjunction with the features of claim 12 and / or a wheel hub drive with a radial flux rotor machine with a drum brake having the features of claim 16.

[0007] Accordingly, the following is planned: - A radial flux rotor machine for a wheel hub drive with a drum brake, comprising a stator with a stator core; a rotor associated with the stator core; a bearing shield supporting the stator core; a brake drum arranged radially inside the rotor and fixed on a wheel hub; a brake unit received in the brake drum; and a parking brake actuator operatively connected with the brake unit, wherein the brake unit is arranged directly on a first surface of the bearing shield facing the stator core and the parking brake actuator is arranged on a second surface of the bearing shield facing away from the first. - The use of a drum brake unit in a radial flux rotor machine for a wheel hub drive, in particular a radial flux rotor machine according to the invention, comprising a brake drum arranged on a wheel hub; a brake unit received in the brake drum, in particular comprising at least a brake actuator, also referred to as a brake cylinder, brake shoes, at least one abutment for the brake shoes, at least one incremental adjuster and / or return springs engaging with the brake shoes; and a parking brake actuator, wherein the brake unit and the parking brake actuator are mechanically fixed directly on the bearing plate of the radial flux twin rotor machine supporting the stator. - A wheel hub drive with a radial flux rotor machine according to the invention with a drum brake.

[0008] The underlying insight of the present invention is that, for the installation of a brake unit consisting of a drum brake and a parking brake actuator arranged on a separate carrier plate, large openings must be provided in the bearing shield of the stator for the passage of the parking brake actuator, which reduce the stiffness of the bearing shield of the stator and additionally necessitate partially large radial seals to seal the brake unit and the parking brake actuator against the openings.

[0009] The underlying idea of ​​the present invention is to arrange the brake unit and the parking brake actuator directly on the stator's bearing plate, in particular by mechanically fixing them in place. This avoids a large opening in the bearing plate and increases the rigidity of the support plate. Furthermore, the functions of the brake unit's support plate are fully integrated into the stator's bearing plate, thus eliminating the need for the support plate altogether. This simplifies the assembly of the brake unit in the radial flux rotor machine, resulting in a reduction in the weight and complexity of the drum brake and the entire wheel hub drive.

[0010] Advantageous designs and further developments result from the further sub-claims as well as from the description with reference to the figures in the drawing.

[0011] According to one embodiment, the arrangement is provided via fastening means, in particular screws, guided through the bearing plate. The fastening means allow for the simple mounting of the brake unit on the one hand and the parking brake actuator on the other.

[0012] According to one embodiment, support points for the brake unit are provided in the bearing plate. These support points define the mounting position of the brake unit and thus facilitate precise positioning and support of the brake unit on the bearing plate.

[0013] According to one embodiment, the support points are at least partially formed by inserts inserted into or placed on the bearing plate, with such inserts achieving advantages in the friction optimization between the movable brake shoes and the bearing plate, particularly in the support points for the brake shoes of the brake unit.

[0014] According to one embodiment, the inserts are designed as steel inserts. This reduces friction between the moving parts of the brake unit, particularly the brake shoes and the bearing shield, and thus advantageously minimizes wear in the areas of the bearing shield that are subject to high frictional stress.

[0015] According to one embodiment, a heat shield is provided between the brake unit and the rotor, protecting the brake unit. This protects the bearing shield and the rotor from the heat generated during braking, thus preventing heat-induced deformation of the bearing shield and demagnetization of the rotor. The heat shield can be a separate element, inserted between the brake unit and the bearing shield, for example, during assembly, or placed on top of the bearing shield or the brake unit. In particular, it can be a ring-shaped heat shield that substantially corresponds to the brake unit, especially in terms of surface area, or surrounds the brake unit or the brake drum. Furthermore, it is also possible to integrate the heat shield into the bearing shield or the brake unit during manufacturing.The heat shield preferably surrounds the contact surface and / or circumference of the brake unit on the bearing shield in terms of size and shape, or has an area corresponding to or larger than that covered by the brake unit. All heat protection materials known to those skilled in the art are suitable as heat shields.

[0016] According to one embodiment, a seal is provided between the brake drum and the bearing shield, the seal being designed in particular as an annular labyrinth seal. This prevents brake dust from escaping the drum brake and accumulating in the wheel hub drive, the rotor, or on the stator or stator core. This avoids or reduces malfunctions and downtime of the electric machine.

[0017] According to one embodiment, the bearing shield provides an inspection opening, which allows access to the brake unit and is particularly lockable. This enables a visual and functional inspection of the brake unit, especially of the condition of the brake shoes and the wear of the brake linings, and allows inspection without disassembling the entire unit.

[0018] According to one embodiment, the parking brake actuator comprises a gear unit, in particular an electromechanical gear unit. Due to the arrangement of the parking brake actuator according to the invention, it is not necessary to use a brake cable laid at, for example, a 90° angle relative to the brake unit, thereby achieving a more efficient braking effect of the parking brake.

[0019] According to one embodiment, the brake unit in the wheel hub drive can be mounted from the drive side and the parking brake actuator from the suspension side. The integrated solution proposed according to the invention thus allows for separate installation of the brake unit or drum brake and the parking brake actuator in a wheel hub drive from two sides. This significantly reduces the number of openings in the stator's bearing shield, resulting in increased rigidity and greater design freedom. Additional large radial seals are no longer required; the openings in the bearing shield are closed by the brakes or brake components from both sides or—if necessary—by significantly smaller seals.Furthermore, the solution according to the invention enables the complete integration of the functions of the drum brake into the bearing shield of the stator of the radial flux rotor machine, which leads to a reduction in weight and complexity, since the conventionally used support plate for the brake unit, which carries the brake unit and the parking brake actuator and is provided as a separate, in particular pre-assembled, element, is eliminated.

[0020] According to one embodiment, the radial flux rotor machine is designed as a radial flux double-rotor machine with a first rotor arranged radially inside the stator core and a second rotor arranged radially outside the stator core. Radial flux double-rotor machines with two rotors rigidly connected to each other, also referred to simply as double rotors, multiple rotors, or dual rotors, increase both the torque density and the efficiency of electric drives. Radial flux double-rotor machines offer significant advantages in terms of achievable efficiency and the required installation space in the wheel hub drive.

[0021] According to one embodiment of the use described above, the brake unit and the parking brake actuator are arranged on opposite surfaces of the bearing shield supporting the stator core, and are in particular mechanically fixed. In one embodiment, the brake unit can be mounted from a drive side of the radial flux twin-rotor machine, and the parking brake actuator can be mounted from a suspension side of the radial flux twin-rotor machine. The use according to the invention thus provides an integrated solution and simultaneously allows separate installation of the brake unit or a drum brake and the parking brake actuator in a wheel hub drive, without having to provide a separate mounting plate for the brake unit.This allows for a significant reduction in the number of openings, particularly for the passage of the parking brake actuator through the stator end shield, compared to conventional arrangements with a separate support plate, thereby increasing the stiffness of the end shield. Additional large radial seals are no longer required; the openings in the end shield are closed by the brakes or brake components from both sides, or—if necessary—only by significantly smaller seals. Furthermore, the inventive design enables the complete integration of the drum brake functions into the end shield, thus eliminating the need for the conventionally used support plate for the brake unit.

[0022] According to one embodiment of the application, the bearing shield is connected to a mechanically fixed base of the radial flux rotor machine. This allows for a significantly more compact design of the entire electric machine, particularly a wheel hub drive.

[0023] The above embodiments and further developments can be combined with one another as appropriate. Further possible embodiments, further developments, and implementations of the invention also include combinations of features of the invention described previously or subsequently with regard to the exemplary embodiments, even if not explicitly mentioned. In particular, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the present invention. CONTENT OF THE DRAWING

[0024] The present invention will be explained in more detail below with reference to the exemplary embodiments shown in the schematic figures of the drawing. These figures show: Fig. 1 a perspective exploded view of a wheel hub drive with a radial flux rotor machine according to an embodiment of the invention; Fig. 2. A representation of the wheel hub drive according to an embodiment of the invention in the assembled state in a top view; and Fig. 3 a sectional view of the wheel hub drive with a radial flux double rotor machine according to an embodiment of the invention in the assembled state.

[0025] The accompanying figures are intended to provide a further understanding of the embodiments of the invention. They illustrate embodiments and, in conjunction with the description, serve to explain the principles and concepts of the invention. Other embodiments and many of the advantages mentioned will become apparent with reference to the drawings. The elements of the drawings are not necessarily shown to scale.

[0026] In the figures of the drawing, identical, functionally equivalent and similarly acting elements, features and components - unless otherwise stated - are each provided with the same reference symbols. DESCRIPTION OF EXAMPLES OF EXECUTION

[0027] Fig. Figure 1 shows a wheel hub drive 1 in a perspective exploded view. The wheel hub drive 1 has, on its drive side A, where the wheel is mounted in the completed vehicle, a radial flux rotor machine, in the exemplary embodiment a radial flux double rotor machine 10, arranged as the drive. This has a drive unit mounted on a Fig. 1 unrecognizable base, for example the housing 13 of an integrated inverter of the electric machine (cf. Fig. 2), , fixed stator 14, with a stator core 16 fixed on a bearing plate 15 in the assembled state. The bearing plate 15 has a central opening 33 for the passage of the vehicle-side wheel hub 17. The double rotor 11, which can be connected to the wheel hub 17, has a radially inner first rotor 18, which is arranged inside the stator core 16 in the assembled state, and a radially outer second rotor 19, which is arranged outside the stator core 16 in the assembled state (see [reference]). Fig. 3) The brake drum 20 is arranged inside the double rotor 11 and is connected to the wheel hub 17 during assembly. In the assembled state, the brake drum 20 accommodates the brake unit 21, which, in addition to the brake shoes 22, may also include the brake actuator 23, at least one abutment 24 for the brake shoes 22, at least one incremental adjuster 25, and return springs 26 that engage with the brake shoes 22.

[0028] The brake unit 21 is mounted directly on the bearing plate 15 from the drive side A. Fastening elements (not shown), such as screws, are guided through the bores 27 provided in the bearing plate 15 from the suspension side B of the drive and connect the brake unit 21, or parts thereof, to the bearing plate 15, so that the brake unit 21 is mounted directly on the bearing plate 15. The brake unit 21 is supported on the bearing plate 15 at several support points 32. These can be formed, at least partially, by inserts 35 that are either inserted into or placed on the bearing plate 15. Such inserts 35 prove particularly advantageous at the support points 32 for the brake shoes 22 of the brake unit 21 in order to optimize friction between the brake shoes 22 and the bearing plate 15.In this particular case, the use of steel inserts proves advantageous, and the use of steel inserts need not be limited to the support points 32 for the brake shoes 22.

[0029] The in Fig. The parking brake actuator 28, also shown, is supplied from the suspension side B and mounted directly on the end plate 15 of the stator 14, for example, by being bolted to it. The connection to the brake unit 21 is then established via a brake cable 37 fed through the bushing 36. By directly arranging the brake unit 21 on a drive-side first surface 29 of the end plate 15 facing the stator 14 and supporting the stator core 16, and the parking brake actuator 28 on a suspension-side second surface 30 of the end plate 15 facing away from the first, a separate support plate for the brake unit 21 and the parking brake actuator 28 is unnecessary. This also eliminates the need for larger openings in the end plate 15, which are required for the parking brake actuator 28 when using brake units 21 with support plates.Furthermore, the parking brake actuator 28 can be positioned relative to the brake unit 21 in such a way that no brake cables 37 are required, or only short ones that are not angled within the brake unit 21, thereby increasing the efficiency of the parking brake. Avoiding larger openings in the bearing plate 15 significantly increases its rigidity. The embodiment according to the invention also allows for a more compact design of the radial flux twin-rotor machine 10 and the wheel hub drive 1 equipped with it. The condition of the brake unit 21, in particular the wear of the brake linings 39 applied to the brake shoes 22, can be easily checked via inspection openings 38 provided in the bearing plate 15 without disassembling the entire unit.

[0030] Fig. Figure 2 shows the rear view, i.e., the view from the suspension side B, of the mounted electric machine. Fig. 1. The bearing shield 15 is visible, which in the exemplary embodiment is mechanically connected from the drive side A to the housing 13 enclosing an integrated inverter. The wheel hub 17, which carries the rotor 11 and the brake drum 20 on the drive side, is guided through the central opening 33 in the bearing shield 15 of the stator 14. The parking brake actuator 28 with electromechanical gear unit 40, which is supplied from the suspension side B, is mechanically fixed to the bearing shield 15 and is also arranged directly on the bearing shield 15 from the suspension side B. To establish an operative connection between the in Fig. Only a small, in Fig. 3. An opening concealed by the parking brake actuator 28 is provided. The design according to the invention avoids the use of a common support plate for the brake unit 21 and the parking brake actuator 28, and eliminates the need for larger mounting and feed-through openings in the bearing plate 15, which would, in particular, reduce its rigidity and also necessitate the arrangement of large-area seals. The openings required for the passage of, for example, brake cables 37 are sealed by the attached elements themselves. An inspection opening 38 for inspecting the brake shoes 22 or brake linings 39 is also provided in the bearing plate 15.

[0031] Fig. Figure 3 shows the wheel hub drive 1 with a radial flux double rotor machine 10. Fig. 1 in the assembled state in a sectional view. The section was made along the in Fig. Section line CC specified in Figure 2. In the exemplary embodiment, the rotor 11 is designed as a double rotor with a radially inner first rotor 18, which is arranged inside the stator core 16, and a radially outer second rotor 19, which is arranged outside the stator core 16. The stator core 16 is fixedly connected to the bearing shield 15 of the stator 14. The double rotor 11 surrounds the brake drum 20, which in turn connects the brake unit 21 with the components already mentioned in connection with Fig.The brake unit 21 is enclosed by the elements described in Section 1. It is located directly on the end shield 15 of the stator 14. The abutment 24 of the brake unit 21 is bolted to, for example, a steering knuckle (not shown) provided by the vehicle via the fastening element 41 shown here, thus mechanically securing the brake unit 21. A heat shield 34 is provided between the brake unit 21 and the end shield 15. This protects the end shield 15 from heat generated during braking and thus prevents heat-induced deformation of the end shield 15. Furthermore, the heat is shielded from the rotor, protecting it, particularly with regard to demagnetization. The heat shield 34 can be provided as a separate element inserted between the brake unit 21 and the end shield 15 or placed on top of the end shield 15 or the brake unit 21.Furthermore, it is also possible to integrate the heat shield 34 into the bearing shield 15 during its manufacture.

[0032] The wheel hub 17 is guided through the central opening 33 in the bearing plate 15. A circumferential seal 31 is provided between the brake drum 20 and the bearing plate 15, sealing the brake drum 20 and the brake unit 21 arranged therein against the bearing plate 15 and reducing the escape of brake dust into the double rotor 11. In the exemplary embodiment, the seal 31 is designed as a labyrinth seal, without limiting the invention to this.

[0033] Although the present invention has been fully described above with reference to preferred embodiments, it is not limited thereto, but can be modified in many ways. Reference symbol list 1 wheel hub drive 10 Radial flux twin-rotor machine 11 Twin rotor 12 Drum brake 13 cases 14 Stator 15 Storage sign 16 Stator core 17 Wheel hub 18 first rotor 19 second rotor 20 brake drums 21 Brake unit 22 brake shoes 23 Brake actuator 24 abutments 25 incremental adjusters 26 Return spring 27 boreholes 28 Parking brake actuator 29 first surface 30 second surface 31 Seal 32 Support point 33 central opening 34 Heat shield 35 deployment 36 socket 37 Brake cable 38 Inspection opening 39 brake pads 40 Gear unit A Drive side B Suspension side

Claims

[1] Radial flux rotor machine for a wheel hub drive (1) with a drum brake (20), with a stator (14) with a stator core (16); with a rotor (11) associated with the stator core (16); with a bearing shield (15) supporting the stator core (16); with a brake drum (20) arranged radially inside the rotor (11) and fixed on a wheel hub (17); with a brake unit (21) mounted in the brake drum (20); and with a parking brake actuator (28) operatively connected to the brake unit (21), wherein the brake unit (21) is arranged directly on a first surface (29) of the bearing shield (15) facing the stator core (16) and the parking brake actuator (28) is arranged on a second surface (30) of the bearing shield (15) facing away from the first. [2] Radial flux rotor machine according to claim 1, characterized by, that the arrangement is provided via fastening means guided through the bearing shield (15). [3] Radial flux rotor machine according to one of the preceding claims, characterized by , that bearing points (32) for the brake unit (21) are provided in the bearing shield (15). [4] Radial flux rotor machine according to claim 3, characterized by that the support points (32) are formed at least partially by inserts placed in or on top of the bearing plate (15). [5] Radial flux rotor machine according to claim 4, characterized by that the inserts are designed as steel inserts. [6] Radial flux rotor machine according to one of the preceding claims, characterized by , that a heat shield (34) is provided between the brake unit (21) and the bearing shield and / or the rotor (15) to protect the brake unit. [7] Radial flux rotor machine according to one of the preceding claims, characterized by, that a seal (31) is provided between the brake drum (20) and the bearing plate (15). [8] Radial flux rotor machine according to one of the preceding claims, characterized by , that at least one inspection opening (38) is provided in the bearing shield (15) which allows a view and / or access to the brake unit (21). [9] Radial flux rotor machine according to any one of the preceding claims, characterized by , that the parking brake actuator (28) comprises a gear unit (40). [10] Radial flux rotor machine according to any one of the preceding claims, characterized by , that the brake unit (21) can be mounted from a drive side (A) and the parking brake actuator (28) can be mounted from a suspension side (B). [11] Radial flux rotor machine according to one of the preceding claims, characterized by, that the radial flux rotor machine is designed as a radial flux double rotor machine (10) with a first rotor (18) arranged radially inside the stator core (16) and a second rotor (19) arranged radially outside the stator core (16). [12] Use of a drum brake (12) in a radial flux rotor machine for a wheel hub drive (1) according to any one of claims 1 to 11, with a brake drum (20) arranged on a wheel hub (17); with a brake unit (21) received in the brake drum (20), in particular comprising at least a brake actuator (23), brake shoes (22), at least one abutment (24) for the brake shoes (22), at least one incremental adjuster (25) and / or return springs (26) engaging with the brake shoes (22); and with a parking brake actuator (28), wherein the brake unit (21) and the parking brake actuator (28) are arranged directly on the bearing shield (15) of the radial flux rotor machine which supports the stator core (16). [13] Use according to claim 12, characterized by , that the brake unit (21) and the parking brake actuator (28) are arranged on opposite surfaces (29, 30) of the bearing shield (15) supporting the stator core (16). [14] Use according to one of claims 12 or 13, characterized by , that the brake unit (21) is mounted from a drive side (A) of the radial flux rotor machine and the parking brake actuator (28) is mounted from a suspension side (B) of the radial flux rotor machine. [15] Use according to one of claims 12, 13 or 14, characterized by , that the bearing shield (15) is connected to a mechanically fixed base of the radial flux rotor machine. [16] Wheel hub drive with a radial flux rotor machine with a drum brake according to one of claims 1 to 11, wherein the radial flux rotor machine is in particular designed as a radial flux double rotor machine (10).

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