DEVICE FOR GENERATING A VARIABLE ANGULAR MOMENTUM, IN PARTICULAR FOR SPACECRAFT ATTITUDE CONTROL

Abstract

The present invention relates to a device for generating a variable angular momentum or torque, which has a container (1) partially filled with a magnetizable fluid (2) and a device for generating one or several rotating or wandering magnetic fields, with which the magnetizable fluid (2) in the container (1) can be made to continuously move on a closed orbit. The device for generating the rotating or wandering magnetic fields has several electric coils (4), whose coil axes lie in the orbital plane. This structure makes it possible to generate a variable angular momentum without mechanical moved parts or the necessity of external magnetic fields. For example, the device enables a simple and cost-effective spacecraft attitude control.

Claims

1. A device for generating a variable angular momentum, in particular for spacecraft attitude control, which has a container (1) partially filled with a magnetizable fluid (2) and a device for generating at least one rotating or wandering magnetic field, with which the magnetizable fluid (2) in the container (1) can be made to continuously move on a closed orbit in an orbital plane, wherein the device for generating at least one rotating or wandering magnetic field has several electric coils (4) for generating the magnetic field, whose coil axes lie in the orbital plane, and a controller, with which a phase-shifted current flow through the electric coils (4) can be generated and controlled or regulated.

2. The device according to claim 1, characterized in that the container (1) extends around a central area of the device and the electric coils (4) are arranged in the central area.

3. The device according to claim 1, characterized in that the electric coils (4) are arranged around the container (1).

4. The device according to claim 2, characterized in that the container (1) forms a closed channel around the central area.

5. The device according to claim 4, characterized in that the container (1) is annularly formed around the central area.

6. The device according to claim 1, characterized in that the coil axes each are aligned perpendicularly to a next section of the closed orbit.

7. The device according to claim 1, characterized in that an interior volume of the container (1) remaining due to the only partial filling with the magnetizable fluid (2) is filled up with a liquid medium, which has a higher density than the magnetizable fluid (2), and does not mix with the magnetizable fluid (2).

8. The device according to claim 7, characterized in that the liquid medium is a metallic material with a density of ≥6 g.Math.cm.sup.−3, in particular mercury or a eutectic alloy of gallium and indium or gallium, indium, and tin.

9. The device according to claim 1, characterized in that the container (1) is filled with the magnetizable fluid (2) in such a way that several partial volumes of the magnetizable fluid (2) separated from each other are present.

10. The device according to claim 1, characterized in that the controller is designed in such a way that it can generate a phase-offset sinusoidal current flow through the coils (4).

11. The device according to claim 1, characterized in that the container (1) is filled with the magnetizable fluid (2) in such a way that several partial volumes of the magnetizable fluid (2) separated from each other are present.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The proposed device will be exemplarily described in more detail once more below based on exemplary embodiments in conjunction with the drawings. Shown here on:

[0016] FIG. 1 is an exemplary structure of the proposed device, as well as three phases of the movement of the magnetizable fluid;

[0017] FIG. 2 is a schematic illustration of another example for a structure of the proposed device;

[0018] FIG. 3 is a schematic illustration of another example for a structure of the proposed device; and

[0019] FIG. 4 is a schematic illustration of another example for a structure of the proposed device.

WAYS OF IMPLEMENTING THE INVENTION

[0020] The principle of the proposed device is based on a magnetizable liquid being magnetized by locally sufficiently strong magnetic fields, and attracted by these magnetic fields. The magnetized liquid can be correspondingly moved by specifically displacing the positions of high magnetic field strength. In the proposed device, one or several rotating or wandering magnetic fields are now used to make the magnetizable liquid continuously move on a closed orbit, and thereby generate an angular momentum. This is achieved via the suitable arrangement and control of electric coils, whose coil axes lie in the orbital plane.

[0021] Shown in cross section on FIG. 1 is a first example for the structure of the proposed device. FIG. 1a here shows an annularly designed container 1, which forms a closed channel around the central area of the device, and is partially filled with a ferrofluid 2. In this example, the container 1 is filled with the ferrofluid 2 in such a way that two partial volumes of the ferrofluid separated from each other are present, which are separated from each other by a liquid or gaseous medium 3. The annular container 1 envelops a central area in which six coils 4 are arranged in a stellate manner with their axes, as evident from FIG. 1a. A respective two opposing coils 4 form a coil pair connected with each other. The respective open first ends A, B, C of the coil pairs can be put under a voltage by an undepicted controller, so that a current flows through the respective coil pairs. The second ends are here connected with a common ground connection. A suitable phase-offset control of the individual coil pairs by means of the controller makes it possible to generate two rotating magnetic fields 5, through which each of the two partial volumes of the ferrofluid 2 are moved on an annular orbit defined by the container 1. The coil axes of the coils 4 here all lie within the orbital plane of this orbit.

[0022] The generation of the rotating magnetic fields and resultant movement of the ferrofluid are illustrated based on FIGS. 1b-1d. On FIG. 1b, the ends B and C are first put under a voltage by the controller. The current flow thereby generated in the corresponding coil pairs produces the magnetic fields 5 depicted on the figure. As a result, each of the two partial volumes of the ferrofluid 2 flows in the direction of the respective magnetic field 5, as denoted on the figure by the arrows. Since this process takes place symmetrically, an angular momentum is stored in the system, and a torque is exerted. This makes it possible to realize attitude control for a spacecraft in which this device is used. FIGS. 1c and 1d show the continuation of this process by applying the voltage to the ends C and A or A and B. In turn, the figures show the respective magnetic fields 5 this generates and movements of the ferrofluid 2. The individual coil pairs of the device are here preferably controlled by the controller in such a way as to yield a continuous and uniform rotation of the magnetic fields 5. To this end, the controller preferably generates a sinusoidal multiphase alternating current, in the present example a three-phase alternating current using three coil pairs.

[0023] The number of electric coils or coil groups is not limited to the quantity shown on FIG. 1. Rather, more than two coils per group or even more than three groups of coils can also be used. A group formation is also not necessary in each case. The individual coils can also be controlled individually, independently of each other. Depending on how the ferrofluid is allocated, this independent control may also be necessary. Furthermore, it is of course also possible that the container 1 not be annular, but instead be configured with another shape, as exemplarily denoted schematically on FIG. 2. On this figure, the container 1 again forms a channel around a central area, in which the individual coils 4 suitable for generating two rotating magnetic fields are arranged.

[0024] The coils 4 can also be arranged around the container 1, as schematically denoted based on an example on FIG. 3. In this case, for example, the container 1 has a disk-shaped design in a central area of the device, wherein the coils 4 are arranged with their coil axes around the container 1 in a stellate manner in this example. In this example as well, the ferrofluid 2 can be moved on a closed orbit by a rotating magnetic field.

[0025] The coils 4 need not be arranged completely around the container 1 or along the closed orbit. This is shown by example on FIG. 4 as a modification of the embodiment on FIG. 3, but can naturally be applied to other embodiments, for example the one on FIG. 1 or FIG. 2. The movement of the ferrofluid 2 in the orbit area without coils here takes place by momentum transfer within the media 2, 3 in the container 1.

REFERENCE LIST

[0026] 1 Container [0027] 2 Ferrofluid [0028] 3 Liquid or gaseous medium [0029] 4 Coil [0030] 5 Magnetic field [0031] A, B, C Ends of the coils