RU2054334C1 - Magnetic support of gas centrifuge rotor - Google Patents

Abstract

FIELD: mechanical engineering. SUBSTANCE: magnetic support has ferromagnetic bushing mounted coaxial to rotor on its upper cover, circular axially magnetized magnet disposed with gap above bushing coaxially with it in centrifuge housing and polar piece made in the shape of ring with radial shelf near the face end adjoining the lower face end of magnet. Near upper face end the ferromagnetic bushing is equipped with ring-shaped radial protrusion whose thickness is equal to 0.5-1.5 of that of bushing wall and its height is equal to 0.1-0.3 of that of bushing. The width of lower face end of pole piece is equal to 1.8-2.2 of width of upper face end of ferromagnetic bushing and exceeds its width from the side of its interior and exterior surfaces by the same value. The outer diameter of radial shelf of pole piece is equal to 0.92-0.95 of average diameter of ring-shaped magnet. EFFECT: simultaneous lowered pressure on lower support of rotor by 4-5% and increased radial rigidity of upper support of rotor by 8-10% due to indicated relationships of geometric parameters of magnetic support members. 2 dwg

Description

 The invention relates to the upper supports of high-speed rotors with a vertical axis of rotation, by which the rotors are held in a vertical position, for example, gas ultracentrifuge rotors.

 In the upper bearings of high-speed rotors with a vertical axis of rotation, magnetic bearings are used to reduce the pressure on the lower bearing, increasing the reliability and durability of the bearings. To perform the functions of axial unloading of the lower support and stabilization of the vertical position of the axis of rotation of the rotor, the upper magnetic support must have sufficient axial attractive force and radial stiffness and at the same time have relatively small mass and dimensions of the rotating elements.

Known magnetic support of a rotor of a centrifuge rotating around a vertical axis, containing a fixed annular permanent magnet with two pole tips, spaced apart in radius and directed downward, and an anchor mounted on the rotor in the form of a sleeve with two ring protrusions that are opposite to the pole tips, having the same pole pieces dimensions and axial clearance separated from them. The support is also provided with at least one disk mounted on the rotor between the ring electric windings to compensate for part of the rotor weight force and its axial deviations [1]
This magnetic support unloads the lower support of the rotor and stabilizes its vertical position. However, it has a complex structure and has an increased mass and radial dimensions of the armature rotating with the rotor, which is unacceptable for high-speed rotors.

The magnetic support of a vertical centrifuge rotor is also known, containing axial protrusions located on the ring at the upper and lower ends of the rotor and reciprocal axial protrusions on the centrifuge body. In the spaces between the wall of the housing and the protrusions, permanent magnets are mounted on it, with the help of which the housing, the rotating rotor and the protrusions on the housing and on the rotor form a magnetic circuit. Centrifuge body, rotor and protrusions made of ferromagnetic material [2]
In this magnetic support of the rotor, it is necessary to maintain small working gaps between the protrusions on the housing and on the rotor both in the upper and lower parts of the centrifuge, which reduces the reliability of its operation.

The closest technical solution to the proposed one is the magnetic support of the rotor of a gas centrifuge, containing a ferromagnetic sleeve fixed coaxially to the rotor on its upper cover, an annular axial magnetized magnet installed in the centrifuge body above the sleeve coaxially with it, and a pole piece made in the form of a ring with a radial shelf end face adjacent to the bottom end of the magnet [3]
This magnetic support provides the rotation of the rotor without mechanical contact with the elements of the upper part of the centrifuge housing, relieves the lower support by the axial force of attraction of the magnet and stabilizes the position of the axis of rotation of the rotor due to radial rigidity due to the action of an axisymmetric magnetic field. However, the design of the elements of this magnetic support does not allow the efficient use of magnetic field energy to increase the bearing capacity and rigidity of the support. In this support, an increase in the axial force of attraction of the rotor and an increase in radial stiffness can be achieved either by increasing the mass and dimensions of the support elements (including rotating elements), and / or by using new magnetic materials, which significantly increases the cost.

 The problem is solved by the invention, is to reduce the pressure on the lower support and increase the radial stiffness of the upper magnetic support of the high-speed rotor of the gas centrifuge without compromising weight and size and complicating the design of the support by choosing a rational shape, size ratios and relative positions of its elements.

 To solve this problem, in the proposed magnetic support of a vertical rotor of a gas centrifuge, containing a ferromagnetic sleeve fixed coaxially to the rotor on its upper cover, an annular axially magnetized magnet mounted above the sleeve coaxially with it in the centrifuge body, and a pole piece made in the form of a ring with a radial a shelf at the end adjacent to the lower end of the magnet, the ferromagnetic sleeve in the upper part is equipped with an annular radial protrusion, the thickness of which is 0.5-1.5 of the wall thickness of the sleeve, and its height equal to 0.1-0.3 of the height of the sleeve, the width of the lower end of the pole tip is equal to 1.8-2.2 of the width of the upper end of the ferromagnetic sleeve and exceeds the width of its end from the side of the inner and outer surfaces by the same amount, and the outer diameter of the radial shelf of the pole the tip is 0.92-0.95 of the average diameter of the ring magnet.

 Figure 1 shows a partial longitudinal section of a magnetic support; in Fig.2 node I in Fig.1.

The magnetic support includes an axially magnetized ring magnet 3 mounted in a non-magnetic housing 1 coaxially to the vertical rotor 2 with a pole tip 4 at its lower end. The pole tip 4 is made annular with a radial shelf 5 on the side of the end adjacent to the lower end of the magnet 3. Coaxially to the rotor 2, a ferromagnetic sleeve 7 is mounted on its upper cover 6, on which a radial annular projection 9 is made at its upper end 8. End face 8 of the ferromagnetic sleeve 7 is located with a gap K relative to the housing 1 against the lower end 10 of the pole piece 4, while the width S _{3 of the} end 10 is 1.8-2.2 of the width S _{2 of the} upper end 8 of the sleeve 7, and, in addition, the width of the end 10 exceeds the width end 8 from the inner and the outer surfaces of the sleeve 7 by the same amount equal to (S ₃ -S ₂ ) / 2. The annular protrusion 9 in the upper part of the sleeve 7 is made with a thickness S ₂ -S ₁ equal to 0.5-1.5 of the thickness S _{1 of the} wall of the sleeve, or the same thing S ₂ / S ₁ = 1.5-2.5 and the height H _{1 of the} radial protrusion 9 is 0.1-0.3 of the height H _{2 of the} sleeve 7. The outer diameter D _{1 of the} radial shelf 5 of the pole piece 4 is 0.92-0.95 of the average diameter D _{2 of the} ring magnet 3. Rotor 2 relies on the lower support (not shown in the drawing), and in the upper magnetic support does not have mechanical contact with fixed parts. An annular magnet 3 creates an axisymmetric magnetic field, the attractive force of which through the ferromagnetic sleeve 7 unloads the lower support from a part of the rotor weight force and provides the upper support with radial stiffness, that is, the ability to counteract the rotor deviations angular relative to the lower support. The magnetic flux between the poles of the magnet 3 is closed through the pole piece 4 and the ferromagnetic sleeve 7.

 Magnetic support works as follows.

 At rest and during rotation of the rotor 2, an axisymmetric magnetic field holds the ferromagnetic sleeve 7 and the associated rotor in a vertical stationary position, without interfering with the rotation of the rotor. If the rotor deviates from the stationary position, the symmetry of the magnetic field is violated, which creates a radial force that prevents the rotor from deviating and returns the rotor to its original position when the action of the disturbing force ceases.

Due to the presence of a radial protrusion 9 on the sleeve 7, the relative position of the pole tip 4 and the end face of the ferromagnetic sleeve 7 and the choice of the geometric parameters of the magnetic support elements from the proposed ranges of their preferred values, an increased concentration of magnetic flux in the gap between the sleeve 7 and the pole tip 4 is provided, which is compared with known magnetic supports increases the efficiency of unloading the lower support of the rotor and stabilizes the axis of its rotation due to a more complete useful use of energy ology magnetic field and increase the magnetic flux density in the gap K. The experimental studies performed by the applicant have shown that the choice of the geometric dimensions of the members of the magnetic bearings is specified ranges of values deteriorates the operating parameters of the magnetic bearing. For example, increasing the height H _{1 of the} radial protrusion 9 on the upper part of the ferromagnetic sleeve practically does not increase the degree of unloading of the lower support of the rotor and its radial rigidity, but only increases the mass of the ferromagnetic sleeve connected to the rotating rotor. In addition, it was also revealed that in the presence of an inevitable technological dispersion of the values of the attractive forces of the serial magnets used in the support, the spread of the attractive forces in the proposed support is noticeably narrowed, which simplifies the technological requirements in serial production.

Using the invention allows to increase the rigidity of the magnetic support of the rotor of the gas centrifuge by 8-10% and reduce the pressure on the lower support by 4-5%
Reducing the pressure on the lower support of the rotor and increasing the reliability of stabilization of the position of the axis of its rotation increases the reliability and durability of the gas centrifuge.

Claims (1)

 A GAS CENTRIFUGE MAGNETIC ROTOR MOUNT, containing a ferromagnetic sleeve mounted coaxially with the rotor on its top cover, an axially magnetized ring magnet mounted in a centrifuge above the sleeve coaxially with it, and a pole piece made in the form of a ring with a radial shelf at the end face the lower end of the magnet, characterized in that the ferromagnetic sleeve at the upper end is provided with an annular radial protrusion, the thickness of which is 0.5 - 1.5 of the wall thickness of the sleeve, and its height is 0.1 - 0.3 of the height of the sleeve, w the irina of the lower end of the pole tip is equal to 1.8 - 2.2 of the width of the upper end of the ferromagnetic sleeve and exceeds the width of its end from the side of the inner and outer surfaces by the same amount, and the outer diameter of the radial shelf of the pole tip is 0.92 - 0.95 of the average diameter ring magnet.

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