Magnetic Gear

Abstract

Magnetic transmission with three coaxial and rotatable transmission elements (2, 3, 4), two of which have magnetic pole pairs (n, s; N, S) and one of which has magnetic flux elements (8) that conduct a magnetic flux between the magnetic pole pairs (n, s; N, S) of the other two transmission elements (2, 4), characterized in that the two transmission elements (2) having magnetic pole pairs (n, s; N, S) have magnetic pole pairs (n, s; N, S) arranged axially next to each other and / or radially inside or outside of each other with an offset in the circumferential direction, or that at least one of the two transmission elements (2) having magnetic pole pairs (n, s; N, S) has magnetic pole pairs (n, s; N, S) arranged axially next to each other and / or radially inside or outside of each other.s) with an offset in the circumferential direction and the gear element (3) with the magnetic flux elements (8) has magnetic flux elements (8) arranged axially next to each other and / or radially inside or outside of each other with an offset in the circumferential direction, that one of the two magnetic pole pairs (n, s) having gear element (2) has fewer magnetic poles (n, s) and one gear element (4) having magnetic pole pairs (N, S) has more magnetic poles (N, S) than the gear element (3) having the magnetic flux elements (8) has magnetic flux elements (8) and that the offset of the magnetic pole pairs (n, s) of the gear element (2) having fewer magnetic pole pairs (n, s) in the circumferential direction is greater than the offset of the magnetic flux elements (8) of the gear element (3) having the magnetic flux elements (8) in the circumferential direction and greater than the offset of the magnetic pole pairs (N, S) of the gear element (4) having more magnetic pole pairs (N, S) in the Circumferential direction is.

Description

[0001] The invention relates to a magnetic transmission with the features of the preamble of claim 1.

[0002] A magnetic transmission comprises three coaxial transmission elements that are rotatable relative to one another. One of these elements serves as the input, one as the output, and one is fixed against rotation and can be considered the stator. The essential feature is the rotatability of the three transmission elements relative to each other, not necessarily the fixed rotation of one of the three elements. Preferably, the three transmission elements are arranged one inside the other, with an inner transmission element forming a hollow or solid shaft enclosed by the two other transmission elements, which are tubular in shape. The tubular transmission elements can be considered hollow shafts, and an outer transmission element can also be considered a housing. However, it is also possible to arrange the three transmission elements axially side by side, so that their end faces are facing each other, or a hybrid configuration.

[0003] Two of the three gear elements have magnetic pole pairs and one magnetic flux element, which conducts a magnetic flux between the magnetic pole pairs of the other two gear elements. The gear element with the magnetic flux elements can also be considered a coupling element for the magnetic flux between the magnetic pole pairs of the other two gear elements. This gear element is typically located between the two gear elements with the magnetic pole pairs. The number of magnetic pole pairs of the two gear elements and the number of magnetic flux elements differ to achieve a gear ratio increase or decrease. With the same number of magnetic pole pairs in both gear elements and the same number of magnetic flux elements, the magnetic gear has a gear ratio of 1 and is therefore, strictly speaking, a clutch. The gear element with fewer magnetic pole pairs has at least one magnetic pole pair.

[0004] An example of a magnetic transmission is disclosed in German patent application DE 44 05 701 A1. The known magnetic transmission has a cylindrical rotor with a drive shaft, enclosed by a tubular, coaxial soft iron yoke, and a tubular runner, which also concentrically encloses the soft iron yoke and the rotor. The rotor has two semi-cylindrical magnetic poles, i.e., a pair of magnetic poles. The soft iron yoke is smooth on the inside and has, for example, nine outwardly projecting teeth that form magnetic flux elements. The runner has, for example, ten pairs of magnetic poles on its inner surface. When the rotor is driven, the runner rotates at a lower speed in the same direction of rotation. The speed ratio between the runner and the rotor is determined by the number of magnetic pole pairs of the rotor and the runner and the number of teeth of the soft iron yoke.

[0005] Advantages of a magnetic transmission compared to a mechanical gear transmission include freedom from wear, because forces are transmitted contactlessly as magnetic forces, the elimination of gear lubrication, overload protection against high torques due to slippage, smooth running, high efficiency because no mechanical friction occurs, and no bending stress on transmission shafts due to one-sided force application.

[0006] One disadvantage of a magnetic transmission is the ripple in torque transmission. The torque transmitted between the transmission elements depends on the angular position of these elements relative to each other and changes with any rotation of the elements against each other. This results in cogging torques, which ultimately lead to fluctuations in torque.

[0007] Preferably, a magnetic transmission incorporates permanent magnets, although electromagnets are also possible. Due to the simple power supply, electromagnets are particularly suitable for the rotationally fixed transmission element, allowing for the generation of a large magnetic flux and strong magnetic forces, and consequently enabling the transmission of high torques.

[0008] German patent application DE 10 21 461 A and patent application DE 26 31 354 A1 disclose magnetic couplings with two gear elements rotatable relative to each other and having pairs of magnetic poles. No third gear element with magnetic flux elements is present. The gear elements are arranged in a manner comparable to gear drives, namely spur gear drives, internal gear drives, crown gear drives, and special designs. The two gear elements overlap only on small circumferential sections, corresponding to the areas where gears mesh in gear drives. Consequently, the transmissible torque is relatively small. The transmission ratio corresponds to the ratio of the number of magnetic poles of the two gear elements. For smoother operation, the magnets can be inclined, similar to helical gearing.

[0009] German patent application DE 27 53 096 A1 discloses an asynchronous magnetic clutch with magnetic poles arranged at an angle of 45 degrees to each other on both clutch halves to prevent unwanted pulsation of the transmitted torque. The magnetic clutch does not have a constant transmission ratio; instead, a slip occurs between the two clutch halves, which depends on the transmitted torque and the rotational speed. In other words, the transmission ratio changes with the rotational speed and the transmitted torque.

[0010] German patent application DE 28 47 618 A1 also discloses a magnetic coupling in which the magnetic poles on one half of the coupling are offset in the circumferential direction. While this reduces the ripple of a transmitted torque, it also reduces the transmitted torque itself, because only one pair of magnetic poles is congruent at any given time. The other pairs of magnetic poles, due to their circumferential offset, contribute less torque or even generate a torque in the opposite direction, weakening the torque transmission, because their offset opposes a direction of rotation.

[0011] International patent application WO 2011 / 098 317 A2 discloses a switchable magnetic transmission comprising several sets of transmission elements on both an input and an output side. These elements are arranged in the manner of internal gear transmissions and exhibit different gear ratios due to varying numbers of magnetic poles. A tubular transmission element, corresponding to an internal gear and having magnetic poles on its inner surface, transmits a rotation from the input side to the output side.

[0012] The object of the invention is to reduce and preferably eliminate the ripple of the torque transmission of a magnetic transmission, i.e., to reduce or preferably make the torque transmission independent of the angular positions of the transmission elements of a magnetic transmission relative to each other.

[0013] This problem is solved according to the invention by the features of independent claim 1. The gear elements of the magnetic transmission according to the invention have magnetic pole pairs and / or magnetic flux elements that are arranged axially adjacent to one another and / or radially inside and / or outside of one another. These magnetic pole pairs and / or magnetic flux elements have a circumferential offset. Thus, at least two of the three gear elements of the magnetic transmission according to the invention have one or more magnetic pole pairs or magnetic flux elements that are arranged axially adjacent to one another and / or radially inside or outside of one another with a circumferential offset. This circumferential offset of magnetic pole pairs arranged adjacent to one another or inside or outside of one another is also present if the gear element has several magnetic pole pairs that are distributed around the circumference.The offset axially adjacent and / or radially inside or outside of each other arranged magnetic pole pairs and / or magnetic flux elements is present in at least two of the three gear elements of the magnetic transmission; it can also be present in all three gear elements.

[0014] According to the invention, one gear element having magnetic pole pairs has more magnetic pole pairs and the other gear element having fewer magnetic pole pairs than the gear element having magnetic flux elements.

[0015] And according to the invention, the offset of the magnetic pole pairs of the gear element having fewer magnetic pole pairs in the circumferential direction is greater than the offset of the magnetic flux elements of the gear element having magnetic flux elements in the circumferential direction and greater than the offset of the magnetic pole pairs of the gear element (4) having more magnetic pole pairs in the circumferential direction.

[0016] By offsetting the adjacent, inside- or outside-each-of-each-other magnetic pole pairs and / or magnetic flux elements in the circumferential direction, the number of detent positions—that is, the angular positions in which the three gear elements engage—increases, or the detent positions are distributed discretely or continuously in the circumferential direction, thereby reducing the detent torques. In other words, the dependence of the torque transmitted between the gear elements on the angular position of the gear elements relative to each other, and thus torque fluctuations, are reduced. However, the torque transmitted between the gear elements, or the maximum transmissible torque, remains the same; any ripple in the torque transmission during rotation of the gear elements relative to each other is reduced.The magnetic transmission according to the invention is, so to speak, divided into several transmissions which are angularly offset from each other and therefore have their detent positions in different angular positions.

[0017] The greatest reduction in torque ripple of the magnetic transmission according to the invention is achieved when the offset of the magnetic pole pairs or magnetic flux elements is 360 degrees divided by the number of axially adjacent and / or radially inside or outside of each other magnetic pole pairs or magnetic flux elements. In other words, the magnetic pole pairs and / or magnetic flux elements are arranged uniformly around the circumference. Adjacent magnetic pole pairs and / or magnetic flux elements can be offset from each other by a multiple of this angle in the circumferential direction; overall, the axially adjacent and / or radially inside or outside of each other magnetic pole pairs and / or magnetic flux elements should be arranged uniformly around the circumference.

[0018] Helical or spiral magnetic pole pairs and / or magnetic flux elements are also possible, resulting in a transition from a discrete to a continuous circumferential offset of the magnetic pole pairs and / or magnetic flux elements. The angle through which the magnetic pole pairs and / or magnetic flux elements extend circumferentially should be 360 ​​degrees divided by the number of magnetic pole pairs or magnetic flux elements. In other words, the magnetic pole pairs and / or magnetic flux elements should extend once around the circumference divided by the number of magnetic pole pairs or magnetic flux elements. Ideally, the torque transmitted between the gear elements is constant, the gear elements have no detents, and the torque transmission is smooth.

[0019] The invention is explained in more detail below with reference to an embodiment shown in the drawing. The drawing shows: Fig. 1. An end view of a magnetic transmission according to the invention; and Fig. 2 a perspective view of the individual parts of the gearbox made of Fig. 1.

[0020] The drawing is to be understood as a schematic and simplified representation for the purpose of understanding and explaining the invention.

[0021] The in Fig. A highly simplified drawing of the magnetic transmission 1 according to the invention comprises three coaxially arranged transmission elements 2, 3, 4, namely a rotatably mounted shaft as rotor 5, a rotatably mounted, tubular coupling element 6 which concentrically surrounds the rotor and can be considered a hollow shaft, and a rotationally fixed stator 7 which concentrically surrounds the rotor 5 and the coupling element 6 and forms a housing of the magnetic transmission 1. The rotor 5 serves as the input and the coupling element 6 as the output.

[0022] The rotor 5 has narrow, semicircular pairs of magnetic poles n, s, which are arranged axially next to and adjacent to each other. In the circumferential direction, the adjacent pairs of magnetic poles n, s are offset from each other, with the offset being 360 degrees divided by the number of adjacent pairs of magnetic poles n, s ( Fig. 2) The offset from the first magnetic pole pair n, s at one end of the rotor 5 to the last magnetic pole pair n, s at the other end of the rotor 5 is 360 degrees. The intervening magnetic pole pairs n, s are always offset from each other by the same angle in the circumferential direction. This results in a single magnetic pole pair n, s that winds helically around the rotor 5 with exactly one turn along its entire length. However, as described above, the magnetic pole pair n, s is not continuous but is divided into narrow segments, each with the same circumferential offset, so that the total is exactly one turn, and the first and last magnetic pole pairs n, s, as already mentioned, assume the same circumferential position.

[0023] The tubular coupling element 6 has magnetic flux elements 8 that conduct a magnetic flux between the magnetic pole pairs n, s of the rotor 5 and the magnetic pole pairs N, S of the stator 7. The magnetic flux elements 8 have high magnetic conductivity (magnetic permeability); they are ferromagnetic and made, for example, of soft iron (transformer sheet). The magnetic flux elements 8 are spaced apart circumferentially. They are connected circumferentially by a support, which is not shown in the drawing for clarity. The support connects the magnetic flux elements 8 to form the tubular coupling element 6. The support is magnetically neutral; ideally, it does not influence the magnetic flux between the magnetic pole pairs n, s, N, S.The magnetic flux elements 8 can also be connected to each other in other ways, for example with disks at both ends and / or rings at both ends and / or between the two ends. In the exemplary embodiment, the coupling element 6 has nine magnetic flux elements 8 arranged evenly distributed around its circumference. The number of nine magnetic flux elements 8 on the circumference is not essential for the invention; the number of magnetic flux elements 8 around the circumference of the coupling element 6 determines the gear ratio of the magnetic transmission 1.

[0024] In the axial direction, the magnetic flux elements are 8 narrow disks that are offset from each other in the circumferential direction, so that they form helical rods, as shown in Fig. Figure 2 shows the circumferential offset of the axially adjacent magnetic flux elements 8. This offset is 360 degrees divided by the number of adjacent magnetic flux element discs and divided by the number of circumferentially arranged magnetic flux elements 8. As mentioned, the latter number is nine in this embodiment. The total circumferential offset from a first magnetic flux element 8 at one end of the coupling element 6 to a last magnetic flux element 8 at the other end of the coupling element 6 is 360 degrees divided by the number of magnetic flux elements 8 that the coupling element 6 has circumferentially. With nine magnetic flux elements 8 circumferentially, the helical magnetic flux elements 8 wind around the length of the coupling element 6 by 40 degrees circumferentially.This results, with the rotor 5 having a circumferential pair of magnetic poles n, s, in a minimal possible ripple in the torque transmission from the rotor 5 to the coupling element 6. The ripple in the torque transmission decreases with narrower disks of the magnetic flux elements 8 and is minimized or disappears completely if the magnetic flux elements 8 are not divided into disks but are formed as a single, continuous piece.

[0025] In the exemplary embodiment, the stator 7 has eight pairs of magnetic poles N, S on its inner side, which extend axially parallel along its length. Fig.For clarity, only the magnetic pole pairs N, S of the stator 7 are shown in Figure 2. The number of magnetic pole pairs N, S of the stator 7 is calculated as the difference between the number of magnetic flux elements 8 and the number of magnetic pole pairs n, s that the rotor 5 has circumferentially. The transmission ratio of the magnetic drive 1 is calculated as the quotient of the magnetic flux elements 8 that the coupling element 6 has circumferentially and the number of magnetic pole pairs n, s that the rotor 5 has circumferentially.

[0026] In the exemplary embodiment, the magnetic transmission 1 has permanent magnets as magnetic pole pairs (n, s; N, S) of the rotor 5 and the stator 7.

Claims

[1] Magnetic transmission with three coaxial and rotatable transmission elements (2, 3, 4), two of which have magnetic pole pairs (n, s; N, S) and one of which has magnetic flux elements (8) that conduct a magnetic flux between the magnetic pole pairs (n, s; N, S) of the other two transmission elements (2, 4), characterized by, that the two gear elements (2) having magnetic pole pairs (n, s; N, S) have magnetic pole pairs (n, s; N, S) arranged axially next to each other and / or radially inside or outside of each other with an offset in the circumferential direction, or that at least one of the two gear elements (2) having magnetic pole pairs (n, s; N, S) has magnetic pole pairs (n, s) arranged axially next to each other and / or radially inside or outside of each other with an offset in the circumferential direction, and the gear element (3) with the magnetic flux elements (8) has magnetic flux elements (8) arranged axially next to each other and / or radially inside or outside of each other with an offset in the circumferential direction, that one of the two gear elements (2) having magnetic pole pairs (n, s) has fewer magnetic poles (n, s) and one gear element (4) having magnetic pole pairs (N, S) has more magnetic poles (N,S) has a greater magnetic flux element offset (8) than the gear element (3) having magnetic flux elements (8), and that the circumferential offset of the magnetic pole pairs (n, s) of the gear element (2) having fewer magnetic pole pairs (n, s) is greater than the circumferential offset of the magnetic flux elements (8) of the gear element (3) having magnetic flux elements (8), and greater than the circumferential offset of the magnetic pole pairs (N, S) of the gear element (4) having more magnetic pole pairs (N, S). [2] Magnetic transmission according to claim 1, characterized by , that the circumferential offset of the magnetic pole pairs (n, s) is 360 degrees divided by the number of axially adjacent and / or radially inside or outside of each other magnetic pole pairs (n, s) and divided by the number of magnetic pole pairs (n, s) on the circumference. [3] Magnetic transmission according to claim 1 or 2, characterized by, that the offset of the magnetic flux elements (8) is 360 degrees divided by the number of magnetic flux elements (8) arranged axially next to each other and / or radially inside or outside of each other and divided by the number of magnetic flux elements (8) arranged on the circumference. [4] Magnetic transmission according to any one of the preceding claims, characterized by , that at least one gear element (2) has helical or spiral magnetic pole pairs (n, s). [5] Magnetic transmission according to claim 4, characterized by , that the magnetic pole pairs (n, s) wind in the circumferential direction over an angle of 360 degrees divided by the number of magnetic pole pairs (n, s) that the gear element (2) has on its circumference. [6] Magnetic transmission according to any one of the preceding claims, characterized by, that the gear element (3), with the magnetic flux elements (8) has helical or spiral magnetic flux elements (8). [7] Magnetic transmission according to claim 6, characterized by , that the magnetic flux elements (8) wind in the circumferential direction over an angle of 360 degrees divided by the number of magnetic flux elements (8) that the gear element (3) has on its circumference.

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