DE102009039658A1 - Permanent magnet coupling for synchronous transmission of rotary motion, has two rotors which form inner rotor and outer rotor, where two rotors have permanent magnets or hysteresis materials - Google Patents

Abstract

The permanent magnet coupling has two rotors which form an inner rotor (1) and an outer rotor (2). The two rotors have permanent magnets (3) or hysteresis materials (4). The rotors are separated in an overlapping area by a radial gap (S). The overlapping area extends in an axial direction. The rotors are formed in a cascaded manner in longitudinal direction (z). The rotors have sections (1a,1b,1c,2a,2b,2c) provided with permanent magnets (3,3') and hysteresis materials. The sections have different diameters (A-a,A-b,A-c,I-a,I-b,I-c).

Description

The invention relates to a permanent magnet coupling for the synchronous transmission of rotational movements with a first rotor and a second rotor forming an inner rotor and an outer rotor, wherein the first rotor permanent magnets and the second rotor permanent magnets and / or a hysteresis material, wherein the rotors in a in the axial direction extending overlap region are separated by a radial gap and wherein the permanent magnet coupling has adjusting means for a longitudinal displacement between the rotors to allow an adjustment of the transmittable up to a slippage of the permanent magnet coupling torque. The rotors are arranged coaxially, wherein the first rotor having permanent magnets may be provided as an inner rotor or outer rotor. The other rotor forms correspondingly the outer or inner rotor and also has permanent magnets and / or a hysteresis material.

The invention thus relates to permanent magnet couplings in which up to a predetermined, adjustable torque, the transmission of rotational movements takes place synchronously. The transmission takes place by acting over the gap magnetic forces. Below the maximum torque to be transmitted, when using a hysteresis material on one of the rotors, it is magnetized by the permanent magnets of the other rotor in a certain way. Below the maximum torque to be transmitted, the magnetization of the hysteresis material is maintained even when an opposing field occurs. Only when approaching the predetermined limit value of the maximum torque to be transmitted may, depending on the design of the permanent magnet coupling, use a remagnetization of the hysteresis material, as a result of which the coupling begins to slip. In addition, then reverse magnetization losses (hysteresis losses) occur, which cause a deceleration by a conversion into heat energy. As the hysteresis material, for example, an AlNiCo material is suitable, and such alloy may include, in addition to aluminum (Al), nickel (Ni) and cobalt (Co), iron (Fe), copper (Cu) and titanium (Ti).

A permanent magnet coupling with the features mentioned, in which the inner rotor and the outer rotor are each covered with permanent magnets, is from the DE 10 2005 041 973 A1 known. The inner rotor and the coaxially arranged around outer rotor each have a cylindrical shape, wherein the inner rotor can be positioned by adjusting means in the axial direction relative to the outer rotor. By adjusting the overlap between the permanent magnet of the inner rotor and the permanent magnet of the outer rotor can be changed, whereby the transmittable up to a slippage of the permanent magnet coupling torque can be adjusted. By an axial adjustment of the inner rotor relative to the outer rotor, the maximum torque to be transmitted, starting from a maximum value to be set close to zero. The disadvantage here is that a total of a large travel is required for the adjustment of the torque.

From the DE 29 20 706 A1 such as DE 197 46 359 A1 Magnetic slip couplings are known which operate on the eddy current principle. By rotating a rotor provided with permanent magnets eddy currents are induced in the other rotor, which generate an opposing field. In order to be able to induce a corresponding field, the drive-side rotational speed is always greater than the output-side rotational speed of the clutch. There is the problem that increases the torque to be transmitted by the induction with an increase in the speed. To compensate for this increase, it is provided to vary with increasing speed, the air gap between the inner rotor and the outer rotor, wherein the rotors are formed conical. If almost complete coverage is provided on the rotor provided with permanent magnets, the permanent magnets must be adapted in their shape exactly to the conical shape of the respective rotor.

Against this background, the invention has for its object to provide a permanent magnet coupling for the synchronous transmission of rotational movements, which allows the transmission of large torques in a compact design and with respect to the maximum torque to be transmitted has a wide adjustment range. In particular, it is an object of the invention to reduce the travel required for a setting.

Starting from a permanent magnet coupling with the features described in the introduction, the object is achieved in that the rotors are seen stepwise in the longitudinal direction, the rotors each having at least a first provided with permanent magnets or hysteresis material portion and a second provided with permanent magnets or hysteresis material section comprise, which have different diameters. If in this case the inner rotor is moved out of the outer rotor in the direction of increasing diameter, the overlapping area between the rotors, ie the length of the gap extending in the overlapping area, initially changes, as is known from the prior art reduced. At the junctions of the steps, the sections of the inner rotor additionally reach areas of the outer rotor which have a larger diameter. In addition to a reduction in the overlap seen in the axial direction of the inner rotor and outer rotor so that at least partially an increase in the measured gap in the radial direction is achieved. With the increase in the gap, the forces acting on the gap are greatly reduced, so that the adjustment path for setting the maximum torque to be transmitted is considerably reduced by the step-shaped design of the rotors. The individual, stepwise adjoining sections usually have a simple cylindrical shape, wherein the term diameter in the inner rotor refers to the outer diameter and the outer rotor to the inner diameter.

According to a first embodiment of the permanent magnet coupling according to the invention, the first rotor and the second rotor, d. H. Inner rotor and outer rotor, each with permanent magnets. Then there is a synchronous permanent magnet coupling with an inner rotor and an outer rotor, each having permanent magnets, wherein the permanent magnets of the inner rotor and the permanent magnets of the outer rotor are separated in an axially extending overlap region by the radial gap and wherein the permanent magnet coupling adjusting means for a Longitudinal displacement between the inner rotor and the outer rotor, to allow an adjustment of the transmittable up to a slippage of the permanent magnet coupling torque.

If the inner rotor and the outer rotor of the synchronous permanent magnet coupling have the greatest possible overlap, that is, the inner rotor is fully retracted into the outer rotor, are located over the gap each mutually associated portions of the inner rotor and outer rotor, which are usually the same about the circumference Number of permanent magnets having an alternating direction of magnetization. Each permanent magnet of the inner rotor is then opposite to the synchronous transmission of rotational movements across the gap an oppositely poled permanent magnet of the outer rotor.

If, according to a preferred embodiment of the invention, then a larger number of circumferentially arranged permanent magnets is provided on the inner rotor and correspondingly also on the outer rotor from section to section with increasing diameter, are in a reduction of the overlap region by actuation of the adjusting increasingly sections the inner rotor and the outer rotor, which have a different number of permanent magnets, that is, an occupancy ratio equal to one. In these subsections is then no longer as described above each permanent magnet of the inner rotor opposite an oppositely poled permanent magnet of the outer rotor. On the contrary, in these subregions, there are partly mutually repulsive and partly attracting permanent magnets, so that the forces effective for transmitting the torque around the entire circumference cancel out to a great extent. Accordingly, in addition to the reduction of the overlap and the increase of the radial gap in the retraction of the inner rotor from the outer rotor results in a further effect that reduces the maximum torque to be transmitted.

Alternatively, the second rotor, which forms either the inner rotor or the outer rotor, also have a hysteresis material, which initially has a substantially constant magnetization below the maximum torque to be transmitted and thus ensures a synchronous transmission of the rotational movements. As explained above, when the maximum torque to be transmitted is reached, a re-magnetization of the hysteresis material can occur during slipping. If the inner rotor is partially extended relative to the outer rotor, starting from a maximum overlap, then usually no complete remagnetization of the hysteresis material will take place, wherein the respective locally present gap dimension is decisive for the occurrence of the remagnetization. While in the embodiment described above, as a synchronous permanent magnet coupling with permanent magnets on both the inner and the outer rotor in a slippage by the jump from pole to pole force peaks occur, hysteresis clutches, d. H. Permanent magnet couplings, which have permanent magnets on one rotor and hysteresis material on the other rotor, by means of a softer, more uniform slip-through behavior.

Within the scope of the invention, it is also possible to provide hysteresis material and permanent magnets on one or both rotors. Thus, hysteresis material can be provided on one section of the rotor and permanent magnets on another section of this rotor, wherein then, with a maximum overlap, the hysteresis material is always opposed by permanent magnets of the other rotor in order to magnetize the hysteresis material for the synchronous transmission of rotational movements in a defined manner ,

The hysteresis material may be provided at the respective sections without limitation as a circumferential ring or in the form of individual segments. It is also possible to provide more than one circumferentially extending layer of segments.

The individual sections having a different diameter are cylindrical. If the permanent magnets are then placed on the individual sections on the lateral surface, these expediently have a running in the radial direction magnetization, seen in the circumferential direction consecutive permanent magnets of the first rotor having a respective opposite magnetization direction. Although the second rotor has permanent magnets, they may also be arranged with an alternating direction of magnetization.

According to a preferred embodiment of the invention, the sections of the inner rotor and the outer rotor seen in the axial direction in approximately the same length.

The fact that the individual sections are cylindrically shaped in the context of the invention, the possibility for occupancy of the first rotor and possibly also of the second rotor results in simple standardized permanent magnets or segments of hysteresis material. Thus, it is preferably provided that the permanent magnets arranged at the different sections of the first rotor have the same dimensions. This also means that a larger number of permanent magnets is to be provided at the sections with the increase of the diameter around the circumference, if the closest possible packing and thus the largest possible maximum torque to be transmitted is to be achieved.

Due to the simple cylindrical shape of the individual sections, there is the advantage that the assignment of the first rotor and possibly the second rotor can be carried out with substantially parallelepiped-shaped permanent magnets. The permanent magnets produced, for example, by sintering and, if appropriate, cut to a predefined size can thus be produced in a particularly cost-effective manner and without material losses. A recourse to standard commercial dimensions is possible, which in total very low production costs are achieved even in small series or custom-made.

According to a preferred embodiment of the invention, at least 20 permanent magnets or segments of hysteresis material are respectively arranged on the individual sections around the circumference on the rotor forming the inner rotor. In the case of a large number of permanent magnets or segments of hysteresis material around the circumference, there is the advantage that the use of simple cuboidal elements results in a uniform polygon which approaches the circular shape. Regardless of the number of permanent magnets or segments of hysteresis material provided in each case, it can furthermore be provided that these elements of their side facing the gap are rounded to adapt to the respective diameter. For this purpose, the elements, preferably after the common arrangement on the inner rotor or outer rotor, are ground. If, as described above, an occupancy with a large number of elements is provided, there is the advantage that due to the approach to the circular shape in such subsequent processing only a small material removal is necessary, whereby the post-processing can be easily performed and only one overall low material loss leads.

In the context of the invention, alternatively, it is also possible to adapt the permanent magnets or segments during their production to a specific diameter. Thus, the permanent magnets or segments may have a width which increases in the radial direction and, at its side facing the gap, may have a curvature corresponding to the gap diameter. It results in the context of such an embodiment of the advantage that the permanent magnets or segments can be arranged around the circumference without the formation of spaces usually filled with filler, whereby the entire occupied area and thus the maximum torque to be transmitted can be increased. A special adaptation of the permanent magnets or segments comes from economic points of view, especially for large quantities into consideration.

On the permanent magnet of the first rotor, a cover of a non-magnetic material, such as non-magnetic stainless steel, may be provided. By means of this cover, the permanent magnets arranged underneath the gap can be held and protected. The second rotor may also be provided with a corresponding cover, in particular if this also has permanent magnets and / or hysteresis material in the form of segments.

In a manner known per se, a gap pot can be provided in the gap region between the rotors, which, according to the present invention, is to be step-shaped according to the shape of the rotors.

Conventional magnetic materials such as NdFeB, NeFeBo or SmCo can be provided for the permanent magnets. Also with regard to the selection of materials, it is advantageous that, depending on the configuration, it is also possible to use simple cuboid permanent magnets, so that no particular requirements must be imposed on the respective production method.

The invention will be explained below with reference to a drawing showing only one embodiment. They show schematically:

1a and 1b a sectional view through a permanent magnet coupling according to the invention in two functional positions

2 a detailed view of the 1a in the region of a gap between an inner rotor and an outer rotor of the permanent magnet coupling,

3a to 3c Cuts along the lines AA, BB as well as CC the 1a .

4 an alternative embodiment of the invention in fragmentary form in a sectional view.

1a schematically shows a longitudinal section through a part of a permanent magnet coupling for the synchronous transmission of rotational movements. The permanent magnet coupling has an inner rotor 1 as the first rotor and an outer rotor 2 as a second rotor. In the illustrated embodiment, the inner rotor 1 and the outer rotor 2 three sections each 1a . 1b . 1c . 2a . 2 B . 2c on, each with permanent magnets 3 or hysteresis material 4 are occupied in the form of segments. According to an alternative, explained in more detail below embodiment, both rotors 1 . 2 with a permanent magnet 3 . 3 ' be provided.

The inner rotor 1 and the outer rotor 2 are each seen in the longitudinal direction z formed step-shaped, wherein the inner rotor 1 opposite the outer rotor 2 By adjusting means, not shown in the longitudinal direction z is displaceable, whereby an adjustment of the transmittable up to a slippage of the permanent magnet coupling torque is made possible.

1a shows the inner rotor 1 and the outer rotor 2 at a maximum overlap, this functional position corresponds to a maximum value of the maximum torque to be transmitted. The first sections 1a . 1b . 1c of the inner rotor 1 with the respective outer diameters A _a , A _b , A _c , respectively lie the sections 2a . 2 B . 2c of the outer rotor 2 with the inner diameters I _a , I _b , I _c opposite. Between the sections opposite each other in this functional position 1a . 2a . 1b . 2 B . 1c . 2c is only a narrow radial gap S with the gap s (s = I _a - A _a ) is provided, which is required for a wear-free and non-contact transmission of torque. The individual sections 1a . 1b . 1c of the inner rotor 1 and the individual sections 2a . 2 B . 2c of the outer rotor 2 each have approximately the same length l in the axial direction z. The entire overlap between inner rotor 1 and outer rotor 2 is thus about 3 · l.

1b shows a second functional position of the permanent magnet coupling, wherein the inner rotor 1 opposite the outer rotor 2 shifted in the axial direction z by the length of the individual sections l, ie the inner rotor 1 from the outer rotor 2 partially drove out. By the displacement of the inner rotor 1 opposite the outer rotor 2 the overlap is only 2 · l, with a torque transfer substantially only between each two opposing sections 1a . 1b . 2 B . 2c of the inner rotor 1 and the outer rotor 2 he follows.

In addition to the reduction in overlap, the first section now lies 1a of the inner rotor 1 the second section 2 B of the outer rotor 2 as well as the second section 1b of the inner rotor 1 the third section 2c the outer rotor, whereby between the inner rotor 1 and the outer rotor 2 in the entire overlap region there is a greatly increased gap dimension s'(s' = I _b -A _a or s' = I _{c -Ab} ). This greatly increased gap s' leads to a further, very significant reduction in the maximum torque to be transmitted.

With a suitable gradation between the individual sections 1a . 1b . 1c . 2a . 2 B . 2c can be achieved that in the 1b shown functional position corresponds approximately to the functional position of a conventional adjustable permanent magnet coupling, in which the inner rotor is almost completely moved out of the outer rotor. Accordingly, the adjustment required for the adjustment of the maximum torque to be transmitted according to the invention is greatly reduced, whereby the entire permanent magnet coupling can be made very compact.

The illustrated embodiment with three sections 1a . 1b . 1c . 2a . 2 B . 2c on the inner rotor 1 and the outer rotor 2 is purely exemplary. According to the invention, at least two stepwise adjoining sections on the inner rotor 1 and the outer rotor 2 intended.

The 3a . 3b and 3c show starting from the 1a each in a cross section in the functional position of 1a mutually associated, separated by the gap S sections 1a . 2a . 1b . 2 B . 1c . 3c , A comparative consideration of 3a . 3b . 3c with the 2 it can be seen that on all sections 1a . 1b . 1c of the inner rotor 1 same in approximately cuboid permanent magnets 3 are arranged so as to form the sections 1a . 1b . 1c of the inner rotor 1 can be used on standard magnets that are available at low cost. The permanent magnets 3 For example, a standard gauge having a thickness of 3.5 mm, a width of 6 mm and a length of 10 mm may be used. In order to allow adaptation to the different outer diameter A _a , A _b , A _c are around the circumference of the first section 1a of the inner rotor 1 thirty magnets to the second section 1b Thirty-two and around the third section 1c arranged thirty-four magnets, each successively having an opposite, in the radial direction r facing magnetization.

At the sections 2a . 2 B . 2c of the outer rotor 2 are segments of hysteresis material 4 provided with the same dimensions, for example, a thickness of 2 mm, a width of 4 mm and a length of 10 mm, wherein here, depending on the respective diameter I _a , I _b , I _c, a different number is provided.

In the 3a . 3b and 3c is further indicated that the inner rotor 1 a solid cylindrical carrier 5 on the then to adjust the outer diameter A _b , A _c at the second and at the third section 1b . 1c Unterlegelemente 6 are arranged.

To better adapt the permanent magnets 3 and segments to reach the annular gap S, these elements can be adapted, for example, by grinding to the curvature of the gap S. Due to the multitude of adjacent permanent magnets 3 or segments, only a relatively small material removal is required.

The attachment of the permanent magnets 3 and segments of hysteresis material can be made, for example, by adhesive, with preferably also the remaining interstices being poured out. Additionally or alternatively, on the inner rotor 1 and the outer rotor 2 at the individual sections 1a . 1b . 1c . 2a . 2 B . 2c also an exemplary in the embodiment of 4 illustrated cover 7 be provided from a non-magnetic material, which the permanent magnets 3 or segments both protects and holds in position.

4 shows an embodiment in which both rotors permanent magnets 3 . 3 ' exhibit. The inner rotor 1 and the outer rotor 2 indicate at the maximum overlap each over the gap S opposite sections 1a . 2a . 1b . 2 B . 1c . 2c around the circumference an equal even number of permanent magnets 3 . 3 ' on. In the synchronous transmission of rotational movements are so every permanent magnet 3 of the inner rotor 1 an oppositely magnetized permanent magnet 3 ' of the outer rotor 2 opposite, so that the respectively opposite permanent magnets 3 . 3 ' attract.

In the 4 is further exemplified that the permanent magnets 3 . 3 ' are adapted in shape exactly to the respective diameter, whereby intermediate spaces are avoided. On the permanent magnets 3 . 3 ' are protective covers 7 intended. In the longitudinal direction z, the synchronous permanent magnet coupling in the 1 shown step shape, wherein with increasing diameter A _a , A _b , A _c , I _a , I _b , I _c at the individual sections 1a . 1b . 1c . 2a . 2 B . 2c around the circumference also an increasing number of permanent magnets 3 . 3 ' is provided. Between the inner rotor 1 and the outer rotor 2 is a containment shell 8th arranged according to the shape of inner rotor 1 and outer rotor 2 is stepped.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102005041973 A1 [0003]
• DE 2920706 A1 [0004]
• DE 19746359 A1 [0004]

Claims (12)

Permanent magnet coupling for the synchronous transmission of rotational movements with a first rotor and a second rotor having an inner rotor ( 1 ) and an outer rotor ( 2 ), wherein the first rotor permanent magnets ( 3 ) and the second rotor permanent magnets ( 3 ' ) and / or a hysteresis material ( 4 ), wherein the rotors are separated by a radial gap (S) in an overlapping region extending in the axial direction (z), and wherein the permanent magnet coupling has adjusting means for a longitudinal displacement between the rotors, in order to be able to adjust the up to a slippage of the permanent magnet coupling To enable torque, characterized in that the rotors in the longitudinal direction (z) are formed step-shaped, the rotors each having at least a first with permanent magnets ( 3 . 3 ' ) or hysteresis material ( 4 ) ( 1a . 2a ) and a second with permanent magnets ( 3 . 3 ' ) or hysteresis material ( 4 ) ( 1b . 2 B ), which have a different diameter (A _a , A _b , I _a , I _b ,). Permanent magnet coupling according to claim 1, characterized in that all permanent magnets ( 3 . 3 ' ) have a magnetization running in the radial direction (r). Permanent magnet coupling according to Claim 1 or 2, characterized in that the sections having a different diameter (A _a , A _b , A _c I _a , I _b , I _c ) ( 1a . 1b . 1c . 2a . 2 B . 2c ) in the axial direction (z) have an equal length (l). Permanent magnetic coupling according to one of claims 1 to 3, characterized in that the at the different sections ( 1a . 1b . 1c ) of the first rotor arranged permanent magnets ( 3 ) have the same dimensions. Permanent magnetic coupling according to one of claims 1 to 4, characterized in that the permanent magnets ( 3 ) of the first rotor are substantially cuboidal. Permanent magnetic coupling according to one of claims 1 to 5, characterized in that the permanent magnets ( 3 . 3 ' ) are rounded at its side facing the gap (S) for adaptation to the respective diameter. Permanent magnetic coupling according to one of claims 1 to 6, characterized in that seen in the circumferential direction successive permanent magnets ( 3 ) of the first rotor each have opposite magnetization direction. Permanent magnetic coupling according to one of claims 1 to 7, characterized in that the second rotor comprises a hysteresis material ( 4 ), which at the sections ( 2a . 2 B . 2c ) is arranged around the circumference in the form of individual segments. Permanent magnet coupling according to one of claims 1 to 7, characterized in that the inner rotor 1 and the outer rotor 2 Permanent magnets ( 3 . 3 ' ), wherein at a maximum overlap across the gap (S) to each other opposite sections ( 1a . 2a . 1b . 2 B . 1c . 2c ) around the circumference the same even number of permanent magnets ( 3 . 3 ' ) exhibit. Permanent magnetic coupling according to claim 9, characterized in that with increasing diameter (A _a , A _b , A _c I _a , I _b , I _c ) at the sections ( 1a . 1b . 1c . 2a . 2 B . 2c ) the number of circumferentially arranged permanent magnets ( 3 . 3 ' ) increases. Permanent magnetic coupling according to one of claims 1 to 10, characterized in that the permanent magnets ( 3 ) of the first rotor a non-magnetic cover ( 7 ) exhibit. Permanent magnetic coupling according to one of claims 1 to 11, characterized in that in the gap (S) a step-shaped containment shell ( 8th ) between the inner rotor ( 1 ) and the outer rotor ( 2 ) is arranged.

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