JPH0249413B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge damage prevention device for space bearings used in space vehicles such as artificial satellites.

It is known that space vehicles such as artificial satellites become electrically charged due to collisions with charged particles such as photoelectrons and ions in outer space and various other electromagnetic environments in outer space. Magnetic bearings, which are expected to be used in the future for spacecraft such as artificial satellites, often have the rotor completely levitated above the stator, making no contact with the rotor, so the spacecraft is There is a risk that the main body will become electrically charged and a potential difference will occur between the rotor and the stator, which is integral with the projectile main body. On the other hand, when the rotor comes into contact with the stator for some reason or to intentionally erase the charge, it comes into contact with mechanical bearings such as ball bearings to prevent damage to the magnetic bearings. It is thought that the potential difference can be as high as several tens of kilovolts, so contact can cause a large current to flow momentarily through a mechanical bearing, which can cause damage to the balls, inner and outer races, and cage in ball bearings, for example. .

This invention has been made in view of the above-mentioned points, and is a space flight vehicle having a space bearing in which a rotor is supported with respect to a stator by a magnetic bearing, and a mechanical bearing for emergency contact is provided between the stator and the rotor. When a body flies through space, the body is charged with electric charge due to collisions with charged current particles such as photoelectrons and ions or various electromagnetic environments, and the electric charge is discharged between the stator and rotor, creating a mechanical emergency contact mechanism. It is an object of the present invention to provide a discharge damage prevention device for a space bearing, which prevents damage to a bearing, a stator, a rotor, etc. due to discharge flowing into the bearing. The present invention will be explained below based on the drawings.

FIG. 1 is a sectional view of an example of a magnetic bearing used as a space bearing, and FIG. 2 is a plan view of a stator portion and a rotor portion. In these figures, a stator section 1 is integrally fixed to a shaft 3, and a rotor section 2 is configured to rotate around the stator section 1, and a flywheel 4 is attached to the rotor section 2. The stator section 1 includes three flat annular yokes having the same inner diameter and outer diameter, namely, first and second stator yokes 1 disposed on the outside.
1 and 12, and a third stator yoke 13 sandwiched between them, and between the first and third stator yokes 11 and 13 and between the third and second stator yokes 13 and 12. , annular permanent magnets 14 and 15 are sandwiched between them. These permanent magnets 14 and 15 are magnetized in the axial direction, and the polarities of the permanent magnets 14 and 15 are vertically symmetrical with respect to the third stator yoke 13. For example, as shown in FIG. 2, the first and second stator yokes 11 and 12 are radially magnetically divided into eight parts, and cross-shaped first and second electromagnetic yokes 16 and 17 are attached to them, respectively. ing. These electromagnetic yokes 16 and 17 are magnetically connected to the divided parts of the first and second stator yokes 11 and 12 on the X and Y axes in FIG. 2, and are not on the X and Y axes. The divided part is an electromagnetic yoke 16,
17 and the other divisions are substantially magnetically insulated. In addition, each leg portion 16a, 16b, 16c, 16d and 17 of the electromagnetic yokes 16 and 17
A, 17b, 17c, 17d (17b, 17d are not shown) have a total of eight electromagnetic coils 18a, 18b, 18c, 18d and 1.
9a, 19b, 19c, 19d (19b, 19d
(not shown) is wound.

On the other hand, the stator arcs 11 and 1 are provided in the rotor section 2.
Three flat annular yokes with a larger diameter than the stator yokes 11, 12, 13 are provided to rotate around the first and second rotor yokes 21, 22 without contact. The rotor yoke 23 is arranged such that its circumferential surface faces the outer circumferential surface of the first and second stator yokes 11 and 12, respectively, and the inner circumferential surface of the third rotor yoke 23 faces the outer circumferential surface of the third stator yoke 13. . In addition, the rotor yokes 21, 22,
Permanent magnets 24 and 25, which are magnetized in the axial direction similarly to the stator section 1, are arranged between the rotor yoke 23 so that their polarities are symmetrical about the third rotor yoke 23. In addition, the permanent magnet 2 of this rotor part 2
The polarities of 4 and 25 correspond to the permanent magnets 14 and 25 of the stator section 1, respectively.
The direction of polarity is opposite to that of No. 15. 26
is a position sensor for detecting the displacement of the rotor portion 2 in the X-axis direction, and the position sensor for the Y-axis direction is omitted in the drawing. The output of the X-axis position sensor 26 passes through a control circuit and a power amplifier (not shown) to electromagnetic coils 18a, 18c, and 19a wound around the legs 16a, 16c, 17a, and 17c of the electromagnetic yokes 16 and 17 in the X-axis direction. ，
A current is caused to flow through 19c. Similarly, from the Y-axis position sensor (not shown), electromagnetic coils 18b, 18d, and 19 wound around the legs 16b, 16d, 17b, and 17d in the Y-axis direction are detected.
A current is supplied to b and 19d. Reference numeral 27 denotes a ball bearing for supporting the rotor section 2 when the floating control of the rotor section 2 becomes impossible or during a power outage. Note that solid and dotted arrows indicate magnetic flux.

In the magnetic bearing configured as described above, the rotor portion 2 is normally in a state completely floating above the stator portion 1. When a spacecraft equipped with such a magnetic bearing flies through space, it becomes charged due to collisions with charged particles such as photoelectrons and ions, as well as various other electromagnetic environments in space. A potential difference occurs between the two. When the rotor section 2 attempts to come into mechanical contact with the stator section 1 for some reason, it comes into contact with a mechanical ball bearing 27 such as a ball bearing to prevent damage to the magnetic bearing. However, as mentioned above, the number
With a charging voltage that can be 10kV, the ball bearing 27
At the moment of contact, a large current instantly flows through the ball bearing 27. For example, in a ball bearing like the one shown in the figure, damage may occur to the balls 27a, inner and outer races 27b, retainer, etc. Similar damage may occur when the rotor section 2 and stator section 1 are brought into contact in order to intentionally erase the charge.

FIG. 3 is a schematic view of an embodiment of the apparatus for preventing discharge damage for space bearings according to the present invention, and is a partially enlarged sectional view of the ball bearing 27 portion of the magnetic bearing. In the figure, an electrical insulator 28 is fixed to the shaft 3 to which the stator section 1 is fixed, and a ball bearing 27 is fixed to the electrical insulator 28. 29 is a coil,
30 is a resistor, and this coil 29 and resistor 3
0 are connected in series, one end of this series body is connected to the ball bearing 27, and the other end is connected to the shaft 3. Note that the coil 29 and resistor 30 are provided as necessary.

In the above configuration, the case where there is no series body of the coil 29 and the resistor 30 will be first described. Even if the rotor section 2 is displaced for some reason and comes into contact with the ball bearing 27, the stator section 1 will not move because the electrical insulator 28 is interposed in series between the rotor section 2 and the shaft 3. Alternatively, the electric charges charged in the rotor section 2 do not flow from the stator section 1 to the rotor section 2, or vice versa.

Next, a case where there is a series body of the coil 29 and the resistor 30 will be explained. When the rotor part 2 contacts the ball bearing 27, the inductance L of the coil 29 and the resistor 3
A resistor r of 0 forms an equivalent circuit as shown in FIG. In the figure, E is the charging voltage, R is the resistance of the electrical insulator 28, and I is the current flowing from the shaft 3 to the rotor section 2. The current I is as follows: I=E/R+E/r·1/1+jωL/r, R≫r. Therefore, if the voltage is step-like, the current I flows as shown by the solid line in Figure 5, but
In reality, as the current flows, the potential difference E decreases, so the current flows as indicated by the broken line in the figure. In other words, the current I is at the coil 29 at the initial stage of contact between the rotor section 2 and the bearing 3.
is controlled by the inductance L, so that a large current does not instantaneously flow through the ball bearing 27. Damage to the ball bearing 27 is therefore simulated.

FIG. 6 shows another embodiment of the present invention, which has a structure in which an electrical insulator 31 is fixed to the rotor portion 2, and a ball bearing 27 is fixed to this electrical insulator 31.
The coil 29 and resistor 30 in FIG. 3 are omitted.

7 and 8 are views showing other embodiments of the present invention, and in both cases the coil 29 and resistor 30 are omitted. As shown in the figure, this is a case in which electrical insulators 32 and 33 are provided on both the shaft 3 and the rotor section 2.

In addition, although the ball bearing 27 was used in the above embodiment, it may generally be a mechanical bearing.

As explained above, the space bearing discharge damage prevention device according to the present invention inserts an electrical insulator member into the rotor side, stator side, or both of the magnetic bearing so as to electrically insulate between the rotor and the stator. Since a series body of resistance and inductance is connected between the mechanical bearing and the stator, even if the rotor or stator comes into contact with the mechanical bearing for some reason, there will be a series body of resistance and inductance between the stator and rotor. , the electrical charge can be slowly discharged, and the electrical charge can be safely erased.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a magnetic bearing used as a space bearing, FIG. 2 is a plan view of a stator portion and a rotor portion, and FIG. 3 is a schematic diagram of a space bearing discharge damage prevention device that is an embodiment of the present invention. FIG. 4 is an equivalent circuit of a space bearing discharge damage prevention device, FIG. 5 is a diagram showing changes in discharge current, and FIGS. 6, 7, and 8 are diagrams showing other embodiments of the present invention. FIG. In the figure, 2 is a rotor part, 3 is a shaft, 27 is a ball bearing,
28 is an electrical insulator, 29 is a coil, 30 is a resistor, and 31, 32, and 33 are electrical insulators.

Claims (1)

[Claims] 1. A space bearing in which a rotor is supported with respect to a stator by a magnetic bearing, and a mechanical bearing for emergency contact is installed and interposed between the stator and rotor on either the stator or the rotor, and the rotor side and An electrical insulator is inserted into the mechanical bearing on at least one side of the stator so as to electrically insulate between the rotor and the stator, and a series body of resistance and inductance is connected between the mechanical bearing and the stator. Features: Discharge damage prevention device for space bearings.