Single-wheel drive with combined drive / brake unit

Abstract

A combined drive / brake unit (100) integrated into the rim (111) of a wheel (112) includes an axial flux motor (118) and an eddy current brake (120), wherein a common rotor (106) is provided for the axial flux motor (118) and the eddy current brake (120).

Description

Technical Field

[0001] This invention relates to a combined drive / brake unit that can be integrated into the rim of a wheel, wherein the combined drive / brake unit includes an axial flux motor and an eddy current brake. Background Technology

[0002] DE 102020200852 A1 describes a regeneratively operating drive system, particularly for motor vehicles, having an electric motor, power electronics, a mechanical brake, and an eddy current brake that minimizes the load on the mechanical brake. It is proposed that braking force is generated by the action of the mechanical brake and / or the eddy current brake on an actuating unit rotatably connected to the rotor of the electric motor along a rotation axis.

[0003] WO 2019101861 A1 describes a drive and deceleration unit comprising a mechanical brake and an electric actuator, wherein the mechanical brake and the electric actuator are configured as a unit to act on a single wheel interface. Furthermore, a method for controlling or regulating such a drive and deceleration unit is disclosed.

[0004] DE 202005015404 U1 describes a device with a parking brake component, comprising an electric motor, a transmission mechanism, and a spindle unit arranged in series on a common shaft. The connection between the spindle unit and the transmission mechanism is achieved via a form-locking coupling. The electric motor is secured to a cover with bearings, thereby housing the motor and transmission mechanism as structural units within a common cylindrical housing. A plug-in connector for the electric motor is laterally located at the motor-transmission-spindle-unit junction. The independent claim also relates to a method for performing emergency braking in a combined operating and parking brake system. Summary of the Invention

[0005] According to the present invention, a combined drive / brake unit is proposed, which is integrated into the rim of a wheel and includes an axial flux motor and an eddy current brake, wherein a common rotor is provided for the axial flux motor and the eddy current brake. The axial flux motor can be implemented, for example, as a permanently excited or electrically excited synchronous or asynchronous motor; the present invention is described below in reference to a permanently excited synchronous motor.

[0006] In the context of this invention, a “combined drive / brake unit” refers to a component in which the rotor of an axial flux motor and the brake drum of a radial eddy current brake are combined into one unit, thereby achieving a structural dimension and lower weight that are advantageous compared to the prior art.

[0007] In the context of this invention, an eddy current brake is an electromagnetic braking system that, for example, provides braking force to a vehicle in a very low-wear and very material-friendly manner. In an eddy current brake, braking torque is generated according to the principle of eddy current induction, and this braking torque depends on the vehicle's speed and flux. Typical electrical components in an eddy current brake can be implemented, for example, as magnetic coils or electromagnets for generating a magnetic field. Alternatively, the electromagnet can have one or more magnetic coils. Furthermore, the eddy current brake has a rotor, wherein the rotor has a magnetic, conductive material arranged adjacent to the electrical components. The rotor typically has the shape of a disc or annular body.

[0008] A radial eddy current brake is an oriented eddy current brake such that the working air gap is cylindrical relative to the axis of rotation or the point of rotation, and the height of the working air gap is measured radially.

[0009] In the context of this invention, an axial flux motor is an electric motor in which the working air gap is oriented as a circular surface perpendicular to the rotation axis of the motor, and the height of the working air gap is measured along the direction of the rotation axis. An axial flux motor typically includes a rotor and a stator, wherein the rotor, which rotates about the rotation axis, and the stator, which generates a rotating magnetic field, are arranged axially. An axial flux motor can convert electrical energy into mechanical energy and vice versa.

[0010] According to the present invention, the rotor of the eddy current brake and the rotor of the axial flux motor are the same component element, which advantageously combines the axial flux motor and the eddy current brake in a combined structural configuration, and thus combines the driving and braking actions together, achieving space savings and therefore weight reduction compared to conventional drive / brake units.

[0011] In an advantageous design of the combined drive / brake unit according to the present invention, the axial flux motor has a first stator, a second stator, a third stator, and a rotor, the rotor being arranged axially between the first and second stators and capable of rotating relative to them. The axial flux motor is constructed substantially mirror-symmetrically with respect to the rotor.

[0012] In the context of this invention, the stator is a fixed, anti-rotational component surrounding the rotor of the combined drive / brake unit. Here, the radially spaced parts of the stator from the rotor function as eddy current brakes, and the axially spaced parts function as axial flux motors. The stator generates a magnetic field that interacts with the rotor's magnetic field, thus causing torque acting on the rotor. In this case, the torque generated by the axial flux motor causes the rotor to accelerate or decelerate, where electrical energy is converted into mechanical energy, or vice versa. The torque generated by the eddy current brake always acts as a decelerator, where the energy converted in the rotor is converted into heat. In the proposed embodiment, the drive / brake combination includes a first stator and a second stator, with the rotor centrally arranged between the two stators. In such a structure, two effective magnetic air gaps are provided, which, when the rotor is centrally arranged, cause the cancellation of forces in the axial direction. The first and second stators, as general components, have windings implemented in a mirror manner. The windings are, for example, coils arranged around slots in the stator, where the slots are, for example, grooves or deepenings in the stator. The third stator, as a component of the eddy current brake, is arranged around the rotor.

[0013] In the context of this invention, axial arrangement includes the arrangement of components (e.g., rotor, first stator and second stator) along the axis of the column (e.g., drive axis) to transmit energy in the axial direction, i.e., along the axis mentioned.

[0014] Furthermore, the rotor can rotate relative to the first, second, and third stators. The feasibility of the relative rotation of the rotor is caused by the fact that the rotor and stator are not fixedly connected, but have rotational degrees of freedom.

[0015] In an advantageous design of the combined drive / brake unit according to the present invention, the internal region of the rotor has a material with low conductivity or comprises multiple individually insulating plates, and the external region of the rotor has a material with high conductivity.

[0016] In an advantageous design of the combined drive / brake unit according to the present invention, a rotor thermal isolation section is provided to prevent heat input from the eddy current brake to the axial flux motor, particularly in the region of the magnet mounted on the rotor.

[0017] According to the present invention, a thermal isolation section is implemented at the rotor where the axial flux motor and eddy current brake are used together. This prevents heat transfer between the region of the rotor that interacts with the eddy current brake and is heated by braking energy and the region of the rotor that interacts with the axial flux motor. The thermal isolation section, for example, prevents overheating of the magnets, particularly on the rotor, of the combined drive / brake unit. Improvement is achieved by isolating the heat generated by the eddy current brake and preventing overheating of the axial flux motor.

[0018] In an advantageous design of the combined drive / brake unit according to the present invention, the thermal isolation is achieved by an inserted ring.

[0019] The inserted ring can, for example, be made of a material with low thermal conductivity. The ring can also additionally be made of a perforated or porous material to reduce the cross-section available for heat conduction and thus heat transfer. Alternatively to a separate ring, the annular region in the rotor can also be provided with recesses to reduce the cross-section and thus heat transfer.

[0020] In the context of this invention, the ring considered for thermal insulation is, for example, made of ceramic material.

[0021] In one advantageous design of the combined drive / brake unit according to the present invention, the inserted ring has a material made of plastic with low thermal conductivity.

[0022] In one advantageous design of the combined drive / brake unit according to the present invention, the inserted ring has a material made of ceramic with low thermal conductivity.

[0023] In one advantageous design of the combined drive / brake unit according to the present invention, the inserted ring is made of porous material.

[0024] In an advantageous design of the combined drive / brake unit according to the present invention, the thermal isolation portion is achieved by means of a material tapering caused by a notch at the rotor.

[0025] In an advantageous design of the combined drive / brake unit according to the present invention, the rotor has at least one cooling channel in the outermost region of the rotor near the eddy current brake.

[0026] The cooling channel can be similar to a turbine impeller or an internally ventilated brake disc, but is achieved through flow-facilitating through-holes in the rotor in an axial flow manner.

[0027] In the context of this invention, the rotor has a disc structure, wherein the disc has two abutting regions: an inner region extending from the center of the rotor to a specific diameter and functionally representing the rotor of an axial flux motor, and an outer region functionally representing the rotor of an eddy current brake, wherein the outer region extends from the edge of the inner region to the outermost edge, i.e., to the entire diameter of the rotor. Furthermore, the width of the inner region of the rotor can be designed to be smaller than the width of the outermost region of the rotor. Preferably, the inner and outer regions of the rotor are thermally decoupled from each other as efficiently as possible. Preferably, the inner region of the rotor is made of a material optimal for an axial flux motor, characterized by low conductivity or assembled from individually insulated sheets, while the outer region of the rotor is made of a material optimized for eddy current brakes, possessing high conductivity.

[0028] In one advantageous design of the combined drive / brake unit according to the present invention, the axial flux motor has a permanent magnet.

[0029] As an alternative, electrically excited machines can be constructed, in which electromagnets are arranged on the rotor instead of permanent magnets. In another embodiment, an asynchronous motor can also be involved, which has no magnets and instead has a short-circuit cage.

[0030] In one advantageous design of the combined drive / brake unit according to the present invention, the eddy current brake has an electromagnet.

[0031] In an advantageous design of the combined drive / brake unit according to the present invention, cooling airflow extends from the inner tire edge through the cooling channel to the outer tire edge of the rim.

[0032] The rotor is effectively cooled by internal ventilation achieved through cooling airflow via integrated cooling channels. This efficiently prevents the rotor from overheating.

[0033] The outer tire edge is, for example, a vehicle rim or a wheel with a rim that is visible from the outside, wherein the outer tire edge is, for example, obscured from the outside, wherein the inner tire edge is, for example, not visible from the outside.

[0034] According to the present invention, the combined drive / brake unit is used as a single-wheel drive for a vehicle.

[0035] Advantages of the present invention.

[0036] The advantageous structural space requirements within the wheel rim are achieved through the combined drive / brake unit proposed according to this invention. Here, the combined drive / brake unit efficiently utilizes the available structural space within the wheel rim through a compact, combined structure.

[0037] Additionally, the combined structure of the drive / brake unit achieves weight reduction, which leads to improvements in efficiency and the driving range of the vehicle, especially electric vehicles.

[0038] By utilizing the rotor in conjunction with an eddy current brake and an axial flux motor, the number of moving, such as rotating, parts is reduced. This reduction in moving parts results in less wear and maintenance, thereby increasing the vehicle's potential lifespan.

[0039] By using an eddy current brake, wear on the combined drive / brake unit is further reduced because braking is performed without physical contact, thus also achieving a longer lifespan for the combined drive / brake unit.

[0040] The advantageous arrangement of the stator facilitates easy electrical contact between eddy current brakes and axial machinery via multi-pole plugs. Therefore, a highly integrated and cost-effective overall solution is achieved in terms of structural space, mass, assembly, and electrical contact.

[0041] The embodiments of the present invention will be explained in more detail with reference to the accompanying drawings and the following description.

[0042] Permanently excited synchronous motors are shown and described as exemplary axial flux motors, and the invention also includes other embodiments of axial flux motors, such as electrically excited synchronous or asynchronous motors, for example. Attached Figure Description

[0043] in: Figure 1 A schematic diagram of a combined drive / brake unit is shown. Figure 2 A schematic diagram of a combined drive / brake unit with thermal insulation is shown. Figure 3 A schematic diagram of a combined drive / brake unit with an internally ventilated rotor is shown. Detailed Implementation

[0044] In the following description of embodiments of the invention, the same or similar elements are designated by the same reference numerals, and in some cases, repeated descriptions of these elements are omitted. The accompanying drawings are merely schematic illustrations of the subject matter of the invention.

[0045] Figure 1A schematic diagram of a combined drive / brake unit 100 is shown, which is integrated into the rim 111 of the wheel 112. Figure 1 It can be seen that a transmission mechanism 114, a first drive shaft 116, a second drive shaft 117, an axial flux motor 118, and an eddy current brake 120 are integrated within the rim 111 of the wheel 112. The axial flux motor 118 and the eddy current brake 120 are constructed as a combined drive / brake unit 100. (Based on...) Figure 1 The combined drive / brake unit 100 includes a rotor 106, a first stator 102, a second stator 103, a permanent magnet 104 for the rotor 106, and an electromagnet 108 for the eddy current brake 120.

[0046] The rotor 106 is centrally arranged axially between two stators 102 and 103, wherein an axial air gap 124 exists between the rotor 106 and the corresponding stators 102 and 103. The two stators 102 and 103 are symmetrically constructed and, for example, have windings. The windings can have different winding patterns, such as concentric windings or skew windings, depending on the specific design of the axial flux motor 118.

[0047] Permanent magnets 104 are arranged on the rotor 106, and the number of permanent magnets 104 can vary according to the design scheme of the rotor 106.

[0048] Furthermore, the rotor 106 is arranged radially and centrally between the eddy current brakes 120, wherein there is a radial air gap 122 between the outermost diameter, or second diameter 208.1, of the rotor 106, i.e., the outer region 208 of the rotor 106, and the eddy current brake 120, or the electromagnet 108 of the eddy current brake 120.

[0049] Figure 2 A schematic diagram of a combined drive / brake unit 100 with a thermal insulation section 202 is shown, which is integrated into the rim 111 of a wheel 112. Figure 1 It can be seen that a transmission mechanism 114, a first drive shaft 116, a second drive shaft 117, an axial flux motor 118, and an eddy current brake 120 are integrated within the rim 111 of the wheel 112. The axial flux motor 118 and the eddy current brake 120 are constructed as a combined drive / brake unit 100. (Based on...) Figure 2 The combined drive / brake unit 100 includes a rotor 106, a first stator 102, a second stator 103, a permanent magnet 104 for the rotor 106, and an electromagnet 108 for the eddy current brake 120. Furthermore, from... Figure 2It can be seen that the rotor 106 has a thermally insulating portion 202 caused by the ring 204 at the outermost diameter of the inner region 206, that is, at the first diameter 206.1.

[0050] Figure 3 A schematic diagram of a combined drive / brake unit 100 with an internally ventilated rotor 106 is shown, which is integrated into the rim 111 of a wheel 112. Figure 3 It can be seen that a transmission mechanism 114, a first drive shaft 116, a second drive shaft 117, an axial flux motor 118, and an eddy current brake 120 are integrated within the rim 111 of the wheel 112. The axial flux motor 118 and the eddy current brake 120 are constructed as a combined drive / brake unit 100. (Based on...) Figure 3 The combined drive / brake unit 100 includes a rotor 106, a first stator 102, a second stator 103, a permanent magnet 104 for the rotor 106, and an electromagnet 108 for the eddy current brake 120. Furthermore, from... Figure 2 It can be seen that the rotor 106 has a thermal insulation portion 202 caused by the ring 204 at the outermost diameter of the inner region, that is, at the first diameter 206.1. In addition, the outer region 208 of the rotor 106 has a cooling channel 302.

[0051] Internal ventilation of the rotor 106 is achieved through an integrated cooling channel 302 in the outer region 208 of the rotor 106. This can be achieved, for example, through a cooling airflow 304 extending from the inner tire edge 128 toward the outer tire edge 126. The integrated cooling channel 302 protects the rotor 106 from overheating caused by external heat input from the eddy brake 120 (e.g., the brake drum of the eddy brake 120).

[0052] This invention is not limited to the embodiments described herein and the aspects highlighted therein. Rather, numerous variations are possible within the scope of the claims and are within the practice of those skilled in the art.

Claims

1. A combined drive / brake unit (100) integrated into the rim (111) of a wheel (112), comprising an axial flux motor (118) and an eddy current brake (120), wherein, A common rotor (106) is provided for the axial flux motor (118) and the eddy current brake (120).

2. The combined drive / brake unit (100) according to claim 1, wherein, The axial flux motor (118) includes a first stator (102), a second stator (103), and a rotor (106) arranged axially between the first stator (102) and the second stator (103) and capable of rotating relative to them, and the axial flux motor (118) has a mirror-symmetric structure.

3. The combined drive / brake unit (100) according to any one of claims 1 to 2, wherein, The inner region (206) of the rotor (106) is made of a material with low conductivity or comprises multiple individually insulating plates, and the outer region (208) of the rotor (106) is made of a material with high conductivity.

4. The combined drive / brake unit (100) according to any one of claims 1 to 3, wherein, The rotor (106) is provided with a thermal insulation section (202) to prevent heat input from the eddy current brake (120) to the axial flux motor (118), especially in the area of ​​the magnet mounted on the rotor (106).

5. The combined drive / brake unit (100) according to claim 4, wherein, The thermal insulation section (202) is implemented by the inserted ring (204).

6. The combined drive / brake unit (100) according to claim 5, wherein, The inserted ring (204) is made of a plastic material with low thermal conductivity.

7. The combined drive / brake unit (100) according to claim 5, wherein, The inserted ring (204) is made of a ceramic material with low thermal conductivity.

8. The combined drive / brake unit (100) according to claim 5, wherein, The inserted ring (204) is made of porous material.

9. The combined drive / brake unit (100) according to claim 4, wherein, The thermal insulation section (202) is achieved by means of a material tapering caused by a notch at the rotor (106).

10. The combined drive / brake unit (100) according to any one of claims 1 to 9, wherein, The rotor (106) has at least one cooling channel (302) in the outer region (208) of the rotor (106) near the eddy current brake (120).

11. The combined drive / brake unit (100) according to any one of claims 1 to 10, wherein, The axial flux motor (118) has a permanent magnet (104).

12. The combined drive / brake unit (100) according to any one of claims 1 to 11, wherein, The eddy current brake (120) has an electromagnet (108).

13. The combined drive / brake unit (100) according to any one of claims 1 to 12, wherein, The rotor (106) of the axial flux motor (118) has an electromagnet (108).

14. The combined drive / brake unit (100) according to any one of claims 1 to 13, wherein, Cooling airflow (304) extends from the inner tire edge (128) through the cooling channel (302) to the outer tire edge (126) of the rim (111).

15. The combined drive / brake unit (100) according to any one of claims 1 to 14 is used as a single-wheel drive.

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