Foil journal bearing utilizing semi-active dampers

Details Foil journal bearing utilizing semi-active dampers Foil journal bearing utilizing semi-active dampers

2001-07-25

2003-03-04

Footland, Lenard A. (Department: 3682)

Bearings

Rotary bearing

Hydraulic or pneumatic bearing support

C384S106000

Reexamination Certificate

active

06527446

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to foil journal bearings, and more particularly to a foil journal bearing utilizing semi-active dampers which improves the stiffness of the bearing against rotational shaft-supported load and the vibration suppressing capability of the bearing.
2. Description of the Prior Art
In general, a foil journal bearing employs air as lubricating material instead of lubricating oil, and therefore it is generally suitable for a clean mechanical system. Such a foil journal bearing has a relatively wide area for supporting a rotating member in comparison with other bearings, thus having high reliability. Accordingly, the foil journal bearing can be utilized as a supporting bearing for small, general aerial gas turbine engines, turbo expanders, various aerospace auxiliary power units, land transportation means, vapor cycle centrifugal compressors, and various commercial air compressors.
The foil journal bearing should be designed to have load-carrying capacity and stability, and withstand wear due to unstable contact between a shaft and a bearing during its starting and stopping.
FIG. 1
shows a sectional view of a conventional multi-leaf type foil journal bearing. A plurality of axial grooves
12
a
are formed on the inner surface of a bearing housing
12
while being spaced apart from one another. A plurality of the multi-leaf foils
14
are arranged into the axial grooves
12
a
, and support a shaft
10
. The conventional multi-leaf foil journal bearing shown as
FIG. 1
can increase stiffness as being increased the thickness of the multi-leaf foil
14
. However, the conventional multi-leaf type foil journal bearing is problematic in that the thickness of the foil is restricted and the life span of the bearing is restricted due to wear between the shaft
10
and the foils
14
. The vibration of the shaft
10
is controlled by only a factor of the multi-leaf foil
14
, for example, the thickness or the number of the foils, so that it is difficult to control the vibration of the shaft
10
.
FIG. 2
illustrates a sectional view of a bump foil journal bearing in which a top foil
16
and a bump foil
18
are positioned on the inner surface of a bearing housing
12
and support a shaft
10
thereon. The bump foil journal bearing can increase load-carrying capacity by the great stiffness of the bump foil
18
. However, gas in the bump foil
18
leaks in its axial direction, thereby being reduced the damping capacity of the bump bearing. In addition, the conventional bump foil journal bearing is further problematic in that it is difficult to design and form the bump foil
18
.
SUMMARY OF THE INVENTION
The main object of the present invention is to provide a foil journal bearing utilizing semi-active dampers, which improves load-carrying capacity and stability to be high by increasing stiffness and damping capacity.
Another object of the present invention is to provide a semi-active damper foil journal bearing which reduces the damping vibration and instability of the bearing by gas in a space between damper pin and a dimple of the bearing housing and/or which increase the stiffness by the spring under the damper pin when a shaft rotates fast.
In order to accomplish the above object, the present invention provides a foil journal bearing which is provided at an interior surface of the bearing housing with a plurality of foils or one foil for supporting a shaft wherein the bearing comprising a plurality of dampers embedded in an inside portion of its bearing housing while coming into contact with and supporting the plurality of foils or the one foil to increase stiffness and damping capacity of the bearing during rotation of said shaft, wherein each of said dampers is comprised of a damper pin inserted into one of dimples formed on the interior surface of the bearing housing and an elastic spring interposed between a bottom of the damper pin and a bottom of the dimple.
In order to accomplish the above object, the present invention provides a foil journal bearing for supporting a shaft, wherein the bearing comprising a plurality of foils or one foil at an interior surface of the foil journal bearing housing, and a plurality of dampers embedded in the interior surface of the foil journal bearing housing while coming into contact with and supporting the foils or the one foil to increase stiffness and damping capacity of the bearing during rotation of said shaft.


REFERENCES:
patent: 4178046 (1979-12-01), Silver
patent: 4195395 (1980-04-01), Silver
patent: 4227752 (1980-10-01), Wilcock
patent: 4475824 (1984-10-01), Glaser
patent: 4526483 (1985-07-01), Hishikawa
patent: 4552466 (1985-11-01), Warren
patent: 4616388 (1986-10-01), Soum
patent: 4950089 (1990-08-01), Jones
patent: 5911511 (1999-06-01), Saville

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