WOBBLE GEARBOX WITH ONE DRIVE SHAFT AND ONE OUTPUT SHAFT

Description

Technical field

[0001] The invention relates to a wobble gear with a drive shaft and an output shaft, a stator having at least one row of teeth circumferentially, a rotor having at least one row of teeth circumferentially and being freely rotatable on a shaft section rigidly connected to the drive shaft and pivoted at an angle relative to the drive shaft, the rotor being spaced apart from the stator by a circumferentially continuous air gap located directly between the rows of teeth of the stator and the rotor, and at least one magnet for generating a magnetic flux between the rotor and the stator, wherein the rotor and stator have a different number of rows of teeth and axially adjacent rows of teeth of the stator and the rotor are arranged rotated relative to each other. State of the art

[0002] Magnetic transmissions are known from the prior art. For example, KR101462832B1 shows a magnetic coupling in which the stator and rotor are hollow cylindrical and made of several permanent magnets. The stator and rotor are arranged concentrically to each other, with a modulator having a row of teeth located in the air gap between the stator and rotor.

[0003] The AT321051B also shows a magnetic gear unit with three concentrically arranged elements. The outermost and innermost elements are pole rings in which the poles alternate circumferentially. These poles can either be poles of a permanent magnet or be induced by the third element, which is located between the outermost and innermost elements.

[0004] Wobble gears are also known from the prior art. DE102014001263A1 discloses a magnetic wobble gear with a stator and a rotor at least partially mounted in the stator. The rotor is mounted to rotate freely on a shaft section of the drive shaft, which is pivoted at an angle relative to the drive shaft. The rotor has at least one row of teeth with individual magnets on its outer surface, while the stator has two rows of teeth on its inner surface, which are twisted relative to each other. The rows of teeth of the stator and the rotor are separated from each other by a minimal air gap. The magnets of the rows of teeth are arranged such that the magnetic field lines close over adjacent teeth of a row of teeth in the plane spanned by the row of teeth, i.e., essentially perpendicular to the drive and output shafts.Since the rotor is mounted on the pivoted section of the drive shaft, the rotor is set into a wobbling motion when the drive shaft rotates. The rotor then rotates due to the reluctance force, and its tooth rows align with the second tooth row of the stator, which is rotated relative to the first tooth row, in such a way that the teeth of the stator and rotor tooth rows separated by the air gap are as closely aligned as possible. This minimizes the magnetic resistance between the rotor and stator and maximizes the magnetic flux between the opposing tooth rows of the rotor and stator, thus transmitting torque.

[0005] CN105071633A discloses a wobble gear which has rows of teeth whose teeth are formed from respective permanent magnets.

[0006] A disadvantage of the current state of the art, however, is the need for a large number of permanent magnets. The geometry of the permanent magnet surfaces determines the magnetic flux distribution and thus the efficiency of the magnetic coupling. Therefore, the permanent magnets must be spherically shaped using complex manufacturing processes, a process further complicated by the hardness and brittleness of typical permanent magnets. Furthermore, the permanent magnet field makes component assembly more difficult, ultimately increasing the overall time, material, and cost of production. Description of the invention

[0007] The invention is therefore based on the objective of demonstrating a magnetic wobble gear whose magnetic components, despite efficient magnetic coupling properties and precisely determinable field line profile, can be easily machined, thus facilitating the assembly of the magnetic wobble gear.

[0008] The invention, proposed in the form of a wobble gear according to claim 1, solves the stated problem by making the stator and rotor, and thus also the toothed rows, from ferromagnetic material, and by having the dipole of the magnet run transversely to a plane spanned by a toothed row. The dipole is a vector that runs between the entry and exit points of the magnetic field lines. These exit points can be, depending on the magnet used, for example, at the north or south pole of a permanent magnet, or at the ends of the coil of an electromagnet. The teeth of the toothed rows of the stator and rotor are therefore not themselves magnets, but are magnetized by the magnet. The magnet can be attached either to the stator or to the rotor. If it is attached to the stator, the dipole runs parallel to the drive shaft. If the magnet is located on the rotor, the dipole runs parallel to the pivoted shaft spacing.The field line paths resulting from this magnet arrangement are described for the case where the magnet is located on the stator. In the first field line path, both the stator and rotor have at least two rows of teeth. The field lines run from the magnet through the first row of teeth on the stator, bridge the air gap to the opposite row of teeth on the rotor, cross the rotor to reach the second row of teeth on the rotor, and again bridge the air gap to the second row of teeth on the stator. They then pass through this air gap before returning to the magnet and completing the field line. In the second field line path, either the rotor or the stator has only one row of teeth, so the field lines cannot pass through axially adjacent rows of teeth.The field lines thus pass through the air gap via the first row of teeth of the rotor / stator into the single row of teeth of the stator / rotor, and then through this single row of teeth to pass through the air gap a second time at the point where the magnetic resistance to the second row of teeth of the rotor / stator, which is axially spaced from the first, is lowest. The field lines therefore do not close within the planes spanned by the rows of teeth, as in the prior art, but always via at least two axially adjacent rows of teeth of the stator or rotor that are rotated relative to each other. It is clear to those skilled in the art that, with the magnet arranged on the rotor, the field lines only pass through the components described above in a different sequence; however, the resulting technical effect and the orientation of the field lines are the same.The exact position of the dipole relative to the rotor or stator is irrelevant, as long as the field lines follow the path described above due to the dipole's spatial orientation. If no external force acts via the drive shaft, the teeth of several rows of teeth on the stator and motor align themselves in the magnetic field in such a way that the distance between the opposing rows of teeth, separated by the air gap, and thus the magnetic resistance, is minimized. If the rotor is tilted due to the pivoted section of the drive shaft, different rows of teeth on the rotor or stator align themselves in a known manner, thereby transmitting a torque to the stator. Closely adjacent rows of teeth on the stator or rotor can be twisted relative to each other so that they are offset by gaps. Axially spaced rows of teeth can also be designed to form claw poles.

[0009] To make the wobble gear independent of an external power supply, and therefore more energy-efficient and robust, the magnet can be a permanent magnet. This eliminates a potential source of failure, namely the power supply of an electromagnet, particularly when the wobble gear is used in low-maintenance applications. Furthermore, the use of ferromagnetic materials for the stator and rotor reduces the complex manufacturing steps involved with the brittle permanent magnet material.

[0010] To achieve a homogeneous magnetic field despite simple assembly conditions, the magnet can be a ring magnet arranged concentrically to the drive shaft. Such a ring magnet can be easily arranged on or around the stator to ensure the most homogeneous possible distribution of the magnetic field lines within the wobble drive between the rotor and stator. In a particularly preferred embodiment, the ring magnet can be two-pole and axially magnetized, since this allows all the advantages of the wobble drive according to the invention to be implemented with a magnet that is easy to manufacture.

[0011] To achieve the most compact design possible with the most homogeneous magnetic field, the magnet can be a ring magnet arranged concentrically to the shaft section. This would place the magnet inside the wobble gear, minimizing the required installation space while still ensuring the most homogeneous distribution of magnetic field lines within the wobble gear between the rotor and stator. Due to the concentric arrangement to the shaft section, the spatial orientation of the ring magnet changes with the wobble motion of the rotor.

[0012] The torque transmitted to the rotor depends on the strength of the magnetic field acting upon it. This cannot be adjusted during operation with a magnet of constant field strength and spatial position. Therefore, to nevertheless allow adjustment of the transmitted torque, it is proposed that an electromagnet be used to generate an additional magnetic flux between the rotor and stator. This allows the position, current direction, and current intensity of the electromagnet to generate a further magnetic field, which continuously strengthens or weakens the existing magnetic field of the magnet and thus the torque transmitted to the rotor.

[0013] The magnetic field line density decreases with increasing distance from the dipole. Particularly when multiple rows of teeth are used for the stator or rotor, this can result in a reduction of the usable magnetic surface area, i.e., the number of field lines per tooth surface. An improvement in the spatial distribution of the magnetic field lines can be achieved by using a second magnet with an antiparallel dipole, positioned axially apart from the first magnet. The superposition of the fields from the two magnets can thus increase the field line density in the tooth rows, and consequently the transmitted torque, especially in the edge regions of the stator and rotor. In the case of a stator-side arrangement of the second magnet, "axial" means along the drive shaft; in the case of a rotor-side arrangement, it means along the shaft section.

[0014] Despite the generally very low maintenance requirements of magnetic wobble drives, the connection between the shaft section and the rotor, which is difficult to access for maintenance, is subject to abrasive forces due to the rotor's wobbling motion. To reduce material wear at this point, it is proposed that the rotor be mounted on the shaft section via ball bearings. The ball bearings enable the rotor to rotate around the shaft section with minimal friction.

[0015] The rotor's wobble motion makes it difficult to transmit torque to the output shaft. To minimize the axial force transmission caused by the wobble motion during torque transmission to the output shaft under simple manufacturing conditions, the rotor can be connected to the output shaft via a joint that incorporates a spring for wobble compensation. The joint is preferably as rigid as possible in the direction of rotation to prevent unwanted rotation of the output shaft. Brief description of the invention

[0016] The invention is illustrated in the drawing as an example. It shows Fig. 1 shows a section through a wobble gear according to the invention with two rows of teeth on the stator and three rows of teeth on the rotor, a permanent ring magnet arranged on the stator side, and a switchable electromagnet. Fig. 2 shows a section through a wobble gear according to the invention with two rows of teeth on the stator and one row of teeth on the rotor, a permanent ring magnet arranged on the stator side, and a switchable electromagnet. Fig. 3 shows a section through a wobble gear according to the invention with three rows of teeth on the stator and two rows of teeth on the rotor, as well as a permanent ring magnet arranged on the rotor side. Fig. 4 shows a section through a wobble gear according to the invention with three rows of teeth on the stator and four rows of teeth on the rotor, as well as two reverse-polarized permanent ring magnets arranged on the stator side.Fig. 5 a section through a wobble gear according to the invention with four rows of teeth on the stator and three rows of teeth on the rotor, as well as two reverse-polarized permanent ring magnets arranged on the stator side, Fig. 6 a section through a stator and rotor with the course of the magnetic field lines shown and Fig. 7 a schematic partial view of the arrangement of two rows of teeth of the rotor within three rows of teeth of the rotor . Ways to implement the invention

[0017] A wobble drive according to the invention comprises a drive shaft 1 and an output shaft 2, as well as a stator 4 having circumferential rows of teeth 3 and a rotor 6 having circumferential rows of teeth 5. In its function as a wobble body, the rotor 6 is freely rotatable on a shaft section 7 that is offset by an angle relative to the drive shaft 1. The shaft section 7 is rigidly connected to the drive shaft 1, so that rotation of the drive shaft 1 sets the rotor 6 into a wobble motion. The stator 4 and rotor 6 are spaced apart from each other by a circumferential air gap 8. The ferromagnetic stator 4 and the also ferromagnetic rotor 6 are magnetized by a magnet 9, which, in the embodiments shown here, is designed as a ring magnet extending concentrically to the drive shaft 1 or to the shaft section 7. The orientation of the dipole of the magnet 9 depends on whether it is arranged on the stator 4 or on the rotor 6.In an arrangement on the stator 4, the dipole runs parallel to the axis of the drive shaft 1. In an arrangement on the rotor 6, the dipole runs parallel to the axis of the shaft section 7. To ensure efficient torque transmission, the magnet 9 is arranged such that the field lines B of the magnet 9 pass through the stator 4 or the rotor 6 as symmetrically as possible. In the illustrated embodiments, this is the case when the magnet 9 is arranged circumferentially in the center, as is particularly the case with the [example missing]. Fig. 6 As can be seen from the diagram, the teeth of the tooth rows 3 and 5 align themselves with each other due to the magnetic field, in order to minimize magnetic resistance. If the rotor 6 performs a wobbling motion due to the rotation of the drive shaft 1, the teeth of the tooth rows 3 and 5 are no longer aligned with each other. To minimize the distance between the teeth of the tooth rows, and thus the magnetic resistance, the tooth rows 3 and 5 realign themselves. Since the individual tooth rows 3 and 5 of the stator 4 and the rotor 6 are arranged at a twisted angle to each other, this alignment can only be achieved by a rotational movement of the rotor 4, which transmits a torque to the output shaft 2 connected to the rotor 4. A switchable electromagnet 10 can be provided to strengthen or weaken the magnetic field acting on the stator 4 and the rotor 6, or the magnetic field itself.With a second magnet 11, magnetized oppositely to the first magnet 9, the field line density can be further increased by means of teeth of the tooth rows 3 and 5. For particularly wear-free, rotatable mounting, the rotor 6 can be mounted on the shaft section 7 via ball bearings 12. Since the wobbling motion of the rotor 6 makes it more difficult to transmit torque to the output shaft 2, the rotor 6 can be connected to the output shaft 2 via a joint 13 which includes a spring for wobble compensation. Fig. 6 The course of some magnetic field lines B for the embodiment with two rows of teeth on the stator and three rows of teeth on the rotor, with the magnet 9 arranged on the stator side, can be seen. The field lines run via a first row of teeth 3 of the stator 4, across the air gap 8 to a first row of teeth 5 of the rotor 6, cross the rotor 6 to a second row of teeth 5 of the rotor 6, then again across the air gap 8 to bridge the distance to a second row of teeth 3 of the stator 4 and finally enter the magnet 9. Fig. 7 The arrangement of the rotor 6 within the stator 4 can be seen, in particular the twisted arrangement of axially adjacent rows of teeth 3, 5 can be seen.

Claims

1. Wobble gear with a drive shaft (1) and an output shaft (2), a stator (4) comprising at least one tooth row (3) around its circumference, a rotor (6) comprising at least one tooth row (5) around its circumference, which is mounted so as to rotate freely on a shaft section (7) which is rigidly connected to the drive shaft (1) and is pivoted at an angle relative to the drive shaft (1), wherein the rotor (6) is distanced from the stator (4) by an air gap (8) which is continuous around the circumference and located between the tooth rows of the stator (4) and the rotor (6), and at least one magnet (9) arranged on the stator (4) or on the rotor (6) for generating a magnetic flux between the rotor (6) and the stator (4), wherein the rotor (6) and the stator (4) have a different number of tooth rows (3, 5) and axially adjacent tooth rows (3, 5) of the stator (4) and the rotor (6) are arranged in a rotated manner relative to one another, characterized in that the tooth rows (3, 5) of the stator (4) and the rotor (6) are ferromagnetic and can be magnetized via the magnet (9), and that the dipole of the magnet (9) is a vector extending between the entry and exit points of the field lines (B) and extends transversely to a plane spanned by a tooth row in such a way that the field lines (B) always close over at least two axially adjacent, relative to each other rotated tooth rows (3, 5) of the stator (4) or rotor (6).

2. Wobble gear according to claim 1, characterized in that the magnet (9) is a permanent magnet.

3. Wobble gear according to claim 1 or 2, characterized in that the magnet (9) is a ring magnet arranged concentrically to the drive shaft (1).

4. Wobble gear according to claim 1 or 2, characterized in that the magnet (9) is a ring magnet arranged concentrically to the shaft section (7).

5. Wobble gear according to one of claims 1 to 4, characterized in that an electromagnet (10) is provided for generating a further magnetic flux between the rotor (4) and the stator (6).

6. Wobble gear according to one of claims 1 to 5, characterized in that a second magnet (11) with opposite magnetization is provided, which is axially distanced from the first magnet (9).

7. Wobble gear according to one of claims 1 to 6, characterized in that the rotor (6) is mounted on the shaft section (7) via ball bearings (12).

8. Wobble gear according to one of claims 1 to 7, characterized in that the rotor (6) is connected to the output shaft (2) via a joint (13) comprising a spring for wobble compensation.