KR100948905B1 - Long life foil bearing - Google Patents

Abstract

The present invention provides a stable long-life radial foil bearing.

Radial Foil Bearings, Dynamic Pressure Bearings, Air Bearings

Description

Long Life Foil Bearings {long life foil bearing}

Fig. 1: Conventional form of radial foil bearing

Figure 2: Improved Radial Foil Bearing

Dynamic pressure bearings are widely used in high-speed rotating applications due to their low friction loss and the need for liquid lubricating oils. Especially, dynamic pressure bearings are mainly used in high-speed applications that are difficult to support with rolling bearings and where it is difficult to use liquid lubricants. In particular, foil bearings, called compliant hydrodynamic fluid-film bearings, offer significantly higher performances than fixed-type tilt pad bearings, and have made great strides in recent 20 years and have been applied in aircraft air conditioning systems. In particular, it is used in high speed rotary machines such as ultra-high speed cryogenic turbocompressors of more than 100,000 RPM. Foil bearings in aviation have been used in air cooling machines (ACMs), a key component for regulating the pressure and temperature in the cabin in the environmental control system (ECS) since 1970. It provides stable operation for a long enough time compared to ball bearings without polluting the soil and without a fixed maintenance schedule.

Related patents filed in the United States are as follows. 4,300,806; 5,915,841; 5,988,885; 4,465,384; 5,498,083; 5,584,582; 6,024,491; 6,190,048 B1; 4,624,583; 3,893,733; 3,809,443; 4,178,046; 4,654,939; 4,005,914; 5,911,511; 5,534,723; 5,427,455; 5,866,518

Recently, in order to apply a foil bearing to a heavier shaft and a higher rotational speed than the above-described ACM, a bump type foil bearing capable of supporting high loads has been started. Unlike the leaf type, the bump type includes bump-type springs as shown in FIG. 1 and is attenuated by friction of the springs, thereby essentially determining the operating life of the bearings by wear. Of course, the coating applied to the inside diameter of the top foil 2 by the friction between the top foil 2 and the shaft 1 at the time of starting stop may also limit the service life in a vehicle or a small product which repeats the starting stop frequently. For industrial products that are used for a long time, wear by long time drive is the most important life limiting factor rather than start stop.

When friction is reduced to eliminate wear, the damping is reduced and the rotational motion itself becomes unstable, resulting in a shorter life. Therefore, it is an object of the present invention to protect a part having sufficient friction and having no wear margin. In other words, the wear somewhere is inevitable, and the wear is distributed to a large area so that the effect of the wear is minimal.

1 is a conventional general foil bearing type, in which the top foil 2 has a relative movement with respect to the bump 6, so that after a long time of operation, the contact surface of the bump 6 with the top foil 2 is worn out and thus the bump 6 is removed. Will be broken and the bearings will reach the end of their service life.

According to the present invention, since the wear of the bump 6 due to the friction between the bump 6 and the top foil 2 becomes a problem, a part having direct friction while serving as a friction with the spring, which is the main function of the bump 6, We devised a method to increase the area of. In other words, a cover having a thickness that is thick enough to not affect the spring function is sufficiently mounted on the top of the bumps 6 (parts in contact with the top foil 2). Since it is ideal to mount every mountain, but it is difficult to produce, it is preferable to arrange so that one bump cover 7 can protect several mountains. At this time, determining the welding position close to the welding position of the bump 6 and the bump base 5 is a preferable method of reducing the relative movement distance of the mountain.

Thus, even if the bump cover 7 is installed, the bump cover itself is a relative movement, so the entire movement distance becomes the same and does not reduce the amount of friction. Therefore, it is possible to reduce the amount of wear by increasing the friction area under the same damping function.

There is also abrasion between the bump 6 and the bump base 5, but in general, the height of the bump 6 is different so that even when a part of the bump 6 mountain contacts, the bump 6 and the bump base 7 ) Are always in contact with each other so that sufficient load is distributed, which does not significantly affect the service life. However, in some cases, a protective cover can be added between the bumps 6 and the bump base 7 in the same manner. There will be.

As described above, by applying a plurality of bump covers 7 to the bumps 6, the relative movement of the top foils 2 and 6 can be reduced to reduce wear, and the contact between the circle and the circle is circumscribed. The contact between the circle and the straight line can be increased to minimize the wear of the bump 6 by increasing the contact area. In other words, the wear of the bump 6 is minimized, thereby ensuring the life of the bearing itself.

Claims (1)

A plurality of wavy bumps 6 in which mountains and valleys are sequentially formed are arranged on the bump base 5 positioned at a predetermined distance from the outer periphery of the rotating shaft 1 at a predetermined interval, and the shaft 1 In the radial foil bearing provided with the top foil (2) between the and the plurality of bumps (6), And having at least two bump covers 7 welded between the plurality of bumpers 6 and the top foils 2 to the tops of the respective bumpers 6 formed in the top foils 2 direction. Radial foil bearing.

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