RU2237201C2 - Magnetic bearing - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: magnetic bearing has rotor made of a magnetic material and secured to the shaft, stator made of a magnetic material and mounted in front of the rotor, and movable member made of a magnetic material and interposed between them. The movable member is made of balls set in the coaxial passages for movement. The passages are made in the unmovable housing and filled with damping fluid. The housing can be sealed.

EFFECT: simplified assembling of bearings.

2 cl, 5 dwg

Description

The invention relates to mechanical engineering and, mainly, to a magnetic bearing of a vertical shaft.

A vertical shaft magnetic bearing is known in which an annular radially movable element located in the gap between the ends of the stator and rotor magnets is pivotally connected to the housing by means of vertical rigid rods, and damping and elastic links connecting the radially movable element to the housing are located outside the gap at the periphery rolling element [Japan, US Pat. No. 53-25898, F 16 C 32/04, publ. 07/29/78.].

Closest to the proposed support is a magnetic shaft bearing with a vertical axis of rotation, comprising a first annular axially magnetized magnet coaxially mounted on the shaft, a second annular magnet fixedly mounted in the housing with a gap above the first magnet, and a radially movable annular element made of ferromagnetic material located in the gap mounted in a damping fluid [Japan, US Pat. No. 52-27779, F 16 C 32/04, publ. 07/22/77.].

In case of radial oscillations of the shaft due to the magnetic coupling of the radially moving element and the magnet attached to the shaft, the moving element, rolling on balls, will follow the radial movements of the shaft. In this case, the braking forces of the movable element in a viscous medium and the elastic forces due to the presence of lateral stiffness in the magnetic bearing and the elastic suspension of the radially movable element counteract the radial deviations of the shaft.

However, in this magnetic support, the presence of a massive movable element limits the area of effective damping of shaft oscillations, and particles of oil held only by capillary action in the axial clearance between the radially movable element and the end face of the stator magnet can migrate outside the damper and disrupt the operation of the rotating shaft.

The objective of the present invention is to provide a magnetic bearing design that effectively dampens shaft vibrations, simplifies assembly, and eliminates the migration of damping fluid particles from the damper.

The technical result of the invention is to increase the efficiency of suppressing shaft vibrations at various frequencies, simplicity of design and the ability to work in a vacuum cavity.

The essence of the invention lies in the fact that in a magnetic bearing containing a rotor of magnetic material attached to the shaft, a stator of magnetic material located opposite the rotor, and a movable element of ferromagnetic material mounted between them, the movable element is made in the form of balls, freely located in one or more annular coaxial channels with damping fluid, made in a fixed housing.

In addition, the housing may be sealed.

Additionally, spacers of non-magnetic material can be installed between the balls.

The invention is illustrated by drawings, which schematically depict:

figure 1 is a vertical section of a magnetic bearing;

figure 2 - section aa in figure 1;

figure 3 is an embodiment of a bearing with coaxial channels;

figure 4 is a section bB in figure 3;

5 is an embodiment of a bearing with spacers.

The magnetic bearing comprises a rotor 1 of magnetic material, for example steel, attached to the shaft 2, a stator 3 of magnetic material, for example, in the form of a permanent magnet, located opposite the rotor 1, and a movable element made in the form of balls 4 of magnetic material, for example , in the form of steel balls of a ball bearing installed in the gap between the rotor 1 and the stator 3. The balls 4 are freely located in the annular channel 5 with a damping fluid, for example with oil, made in a fixed housing 6, closed by a cover 7.

In the embodiment of the bearing shown in FIGS. 3 and 4, several coaxially arranged annular channels 5 with damping fluid are made in the housing 6, in which the balls 4 are placed. In this embodiment, the stator 3 is made in the form of an electromagnet with a winding 8.

The cover 7 can hermetically close the channels 5 with damping fluid, for example, can be fixed by welding 9 on the housing 6.

In another embodiment of the bearing shown in FIG. 5, spacers 10 of non-magnetic material are installed in the channels 5 between the balls 4.

When the shaft 2 oscillates, the bearing rotor 1 deviates from the axis of the fixed stator 3. The balls 4 under the influence of magnetic force from the rotor 1 move in the channels 5 in the direction of movement of the rotor. When the balls 4 move in a damping fluid (oil), viscous friction forces arise in the channels 5, which impede the movement of the balls and the rotor magnetically coupled to them and suppress the oscillations of the latter. Since the mass of each ball is negligible, the design provides damping of the oscillations of the shaft at different frequencies, which increases the efficiency of the magnetic bearing in various modes.

With a sealed design of the bearing housing 6, the latter can be installed in the vacuum chambers of various devices using rotating shafts on magnetic bearings without violating their vacuum during operation, since the sealed housing completely eliminates the migration of oil particles outside the damper design.

During the operation of the bearing under the action of axial symmetric fields from the stator 3 and rotor 1, the balls 4 are evenly distributed by magnetic forces around the circumference of the annular channel 5. Under the action of asymmetric radial magnetic fields or during installation of the housing with balls in the magnetic bearing system, a uniform distribution of balls can occur 4 through channel 5 and it is possible for the balls 4 to stick together in one or several groups, which will interfere with the effective operation of the bearing. To prevent the balls 4 from sticking together, non-magnetic separators 10 are installed between them, for example, made of plastic, which completely exclude the possibility of uneven distribution of the balls 4 over the channels 5, which could lead to disruption of the bearing.

Since the height of the housing 6 with balls 4 is determined by the diameter of the balls 4 and the thickness of the bottom and cover 7 of the housing, this assembly is practically a washer 1 to 5 mm thick for balls with a diameter of 0.5 to 4 mm, which greatly simplifies the assembly of a magnetic bearing with a damping element .

Claims (3)

1. A magnetic bearing comprising a rotor of magnetic material attached to the shaft, a stator of magnetic material located opposite the rotor, and a movable element of magnetic material mounted between them, characterized in that the movable element is made in the form of balls freely located in one or several annular coaxial channels with damping fluid, made in a fixed housing. 2. The magnetic bearing according to claim 1, characterized in that the housing is sealed. 3. A magnetic bearing according to claims 1 and 2, characterized in that the spacers of non-magnetic material are installed between the balls.

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