KR20220166481A - Air foil journal bearing - Google Patents

Abstract

The present invention relates to an air foil journal bearing in which a bump foil includes an outer bump foil and an inner bump foil, and in a partial area of the outer bump foil or the inner bump foil, a pitch control part in which the pitch of elastic bumps is different from that of the remaining area is formed or a height control part having a height different from that of the remaining area is formed, so that the inner shape of a bearing can be easily controlled with a simple structure, thereby enabling the performance of the bearing to be easily controlled, preventing the manufacturability of a bump foil from being degraded, and improving the vibration damping performance and driving stability.

Description

Air foil journal bearing {Air foil journal bearing}

The present invention relates to an air foil journal bearing that supports a radial load of a rotor using air pressure generated by high-speed rotation of the rotor.

An air foil bearing is a bearing that supports a load by introducing air, which is a viscous fluid, between a rotor or a bearing disc and a foil in contact with a rotor (or a rotating shaft) to rotate at high speed to form pressure.

Among the air foil bearings, the air foil journal bearing is a bearing configured to support a load in a radial direction of the rotor, which is a direction perpendicular to the rotor.

In a general air foil journal bearing, as shown in FIG. 1, bump foils 2a and 2b are installed along the hollow inner circumferential surface of the bearing housing 1, and top foils 3a and 3b are installed inside the bump foils 2a and 2b. The rotor 4 is disposed inside the top foils 3a and 3b so that the rotor can be rotated while the inner circumferential surface of the top foil 3 and the outer circumferential surface of the rotor 4 are spaced apart. In addition, the bump foils 2a and 2b and the top foils 3a and 3b are formed with a bent portion in which one end in the circumferential direction is bent outward in the radial direction, and the bent portion is inserted into the groove formed in the bearing housing 1 and fixed. . Therefore, when the rotor is stopped, the rotor is in contact with and supported by the lower side of the inner circumference of the top foil by its own weight, and when the rotor is rotated and started, the air pressure between the lower side of the rotor and the top foil increases and the rotor moves along the top foil. It floats upward from the lower inner circumferential surface of and rotates.

Here, the conventional air foil journal bearing may be composed of a so-called double bump in which two sheets of bump foils 2a and 2b are overlapped in order to improve damping against vibration.

However, in such a conventional double bump, overlapping and aligning of the peaks and valleys of the elastic bumps 2c of the two sheets of bump foil are repeated along the circumferential direction, and the surface contact overlaps so that there is no spaced gap between the two sheets of bump foil. Since it is a shape, it is difficult to consider both design parameters for manufacturing bump foils and design matters of peripheral parts when design changes, such as when changing the internal shape of the bearing or adjusting the gap between the top foil and the rotor, etc. .

WO 2015/005547 A1 (2015.01.15.)

The present invention has been made to solve the above problems, and an object of the present invention is to add a new parameter to the design parameters of the bump foil so that the internal shape of the bearing can be easily adjusted, thereby manufacturing and managing parts. It is to provide an air foil journal bearing that can solve the problem.

The air foil journal bearing of the present invention for achieving the above object includes a bump foil in which a plurality of concavo-convex elastic bumps formed in the radial direction are formed along the circumferential direction and are provided and coupled to the inside of the bearing housing. An air foil journal bearing comprising: an outer bump foil disposed relatively outward in a radial direction; and an inner bump foil disposed radially inside the outer bump foil and overlapping the outer bump foil. A pitch adjusting portion may be formed in a portion of the outer bump foil or the inner bump foil, wherein the pitch of the elastic bumps is different from that of the rest of the bump foil.

In addition, the outer bump foil and the inner bump foil may be in line contact with each other in the pitch adjusting unit, and the outer bump foil and inner bump foil may be in surface contact with each other in areas other than the pitch adjusting unit.

In addition, the pitch of the elastic bumps in the pitch control unit may gradually decrease or increase along the circumferential direction.

In addition, a bearing housing in which the outer bump foil and the inner bump foil are provided inside and coupled thereto; and a top foil provided inside the inner bump foil, formed in a circumferential direction, and coupled to the bearing housing; It may be further included.

In addition, one end of each of the outer bump foil and the inner bump foil is coupled to and fixed to the bearing housing, the other end of the outer bump foil and the inner bump foil is formed as a free end, and the pitch adjusting unit controls the outer bump foil and a region adjacent to the free end of the inner bump foil.

In addition, the top foil may include a first top foil disposed inside the inner bump foil; a second top foil disposed inside the first top foil; and a third top foil disposed inside the second top foil. Including, the first top foil, the second top foil and the third top foil may overlap each other.

In addition, the free end of the second top foil may be disposed at a lower side with respect to the center of the bearing housing, and the pitch adjusting unit may be disposed at an upper side with respect to the center of the bearing housing.

In addition, the air foil journal bearing of the present invention includes a bump foil in which a plurality of concavo-convex elastic bumps formed in the radial direction are formed along the circumferential direction and are provided inside the bearing housing to be coupled. , The bump foil may include an outer bump foil disposed relatively outward in a radial direction; and an inner bump foil disposed radially inside the outer bump foil and overlapping the outer bump foil. A height adjuster may be formed in a partial area of at least one of the outer bump foil and the inner bump foil so that the height of the elastic bumps is different from that of other areas.

In addition, the outer bump foil and the inner bump foil may be in line contact with each other in the height adjuster, and the outer bump foil and inner bump foil may be in surface contact with each other in areas other than the height adjuster.

Also, pitches of the elastic bumps in the height adjuster may be the same as each other.

In addition, a bearing housing in which the outer bump foil and the inner bump foil are provided inside and coupled thereto; and a top foil provided inside the inner bump foil, formed in a circumferential direction, and coupled to the bearing housing; It may be further included.

In addition, one end of each of the outer bump foil and the inner bump foil is coupled to and fixed to the bearing housing, and the other end of the outer bump foil and the inner bump foil is formed as a free end, and the height adjuster controls the outer bump foil. and a region adjacent to the free end of the inner bump foil.

In addition, the top foil may include a first top foil disposed inside the inner bump foil; a second top foil disposed inside the first top foil; and a third top foil disposed inside the second top foil. Including, the first top foil, the second top foil and the third top foil may overlap each other.

Also, the free end of the second top foil may be disposed at a lower side with respect to the center of the bearing housing, and the height adjuster may be disposed at an upper side with respect to the center of the bearing housing.

The air foil journal bearing of the present invention has an advantage in that it is easy to adjust the performance of the bearing because the inner shape of the bearing can be adjusted with a simple structure.

In addition, there is an advantage in that manufacturability of the bump foil is not deteriorated, and damping performance for vibration and driving stability are improved.

1 is a cross-sectional view showing a conventional air foil journal bearing.
2 and 3 are cross-sectional and partially enlarged views of an air foil journal bearing according to a first embodiment of the present invention.
4 and 5 are conceptual views showing a state in which the outer bump foil and the inner bump foil of the air foil journal bearing according to the first embodiment of the present invention are spread out.
FIG. 6 is a conceptual diagram showing the air pressure field formed by the top foils of the air foil journal bearing according to the first embodiment of the present invention and the pitch adjusting unit when the rotor rotates.
7 is a graph comparing displacement measurement values of a conventional air foil journal bearing and an air foil journal bearing according to the first embodiment of the present invention in vibration evaluation.
8 and 9 are cross-sectional and partially enlarged views of an air foil journal bearing according to a second embodiment of the present invention.
10 and 11 are conceptual views showing a state in which the outer bump foil and the inner bump foil of the air foil journal bearing according to the second embodiment of the present invention are spread out.

Hereinafter, the air foil journal bearing of the present invention having the above configuration will be described in detail with reference to the accompanying drawings.

First of all, the air foil journal bearing of the present invention may be configured to include two or more bump foils. The air foil journal bearing of the present invention may further include at least one of one or more top foils, a bump foil or a key for fixing the top foil, and a bearing housing. Hereinafter, embodiments in which the top foil is composed of three sheets have been described.

<Example 1>

2 and 3 are cross-sectional and partially enlarged views of an air foil journal bearing according to the first embodiment of the present invention, and FIGS. 4 and 5 are external bumps of the air foil journal bearing according to the first embodiment of the present invention. It is a conceptual diagram showing the unfolded state of the foil and inner bump foil.

As shown, the air foil journal bearing according to the first embodiment of the present invention may largely include two bump foils and three top foils, and may further include a key and a bearing housing coupled to the top foil. there is.

The bearing housing 100 may be formed in a cylindrical shape by forming a hollow 110 through which both sides pass in the central axis direction on the inside. In addition, the key groove 120 may be concavely formed at an upper inner portion of the bearing housing 100 to communicate with the hollow 110 . The key groove 120 extends along the central axis direction and may be formed in a form in which both sides pass through in the central axis direction. In addition, the bearing housing 100 may be formed in various shapes.

The bump foil may largely include an outer bump foil 210 and an inner bump foil 220, and the outer bump foil 210 and the inner bump foil 220 are provided on the inner side of the bearing housing 100 to form a bearing housing ( 100) can be combined. In addition, the outer bump foil 210 is disposed relatively radially outward to contact the inner circumferential surface of the bearing housing 100, and the inner bump foil 220 is disposed inside the outer bump foil 210 to form an outer bump foil ( 210 , the outer bump foil 210 and the inner bump foil 220 may be coupled to the bearing housing 100 in an overlapped state. In addition, the outer bump foil 210 and the inner bump foil 220 may have ends in the circumferential direction bent outward in the radial direction, and the bent portion may be inserted into the keyway 120 of the bearing housing 100 and coupled thereto. Thus, the outer bump foil 210 and the inner bump foil 220 may be fixed to the bearing housing 100 without being rotated. In addition, the outer bump foil 210 and the inner bump foil 220 may be formed with free ends in the circumferential direction. In addition, the outer bump foil 210 and the inner bump foil 220 may each have a plurality of elastic bumps 211 and 221 formed in a radially inward convex shape, and the plurality of elastic bumps 211 and 221 may be respectively formed. It may be spaced apart at specific intervals along the circumferential direction to form a repeating form of peaks and valleys.

The top foil may include a first top foil 310, a second top foil 320, and a third top foil 330, and the three top foils are disposed inside the inner bump foil 220 in the radial direction. It can be. Also, the first top foil 310 is disposed on the inside of the inner bump foil 220 to be in contact with the inner bump foil 220, and the second top foil 320 is on the inside of the first top foil 310. The third top foil 330 may be disposed inside the second top foil 320 and may come into contact with the second top foil 320. Thus, three sheets of The top foils may be coupled to the bearing housing 100 in an overlapped state. In addition, the first top foil 310, the second top foil 320, and the third top foil 330 have one end in the circumferential direction outside the radial direction. It is bent toward the side, and the bent part can be inserted into and coupled to the keyway 120 of the bearing housing 100. Thus, the three top foils can be fixed to the bearing housing 100 without being rotated. , The first top foil 310, the second top foil 320, and the third top foil 330 may be formed with free ends in the circumferential direction, and the rotor 500 may be a rotating shaft, and the rotor ( 500) may be disposed inside the third top foil 330. In addition, in a state in which the rotor 500 is not rotated, the rotor 500 is in contact with and supported by the third top foil 330 by its own weight. state, and when the rotor 500 is rotated at high speed, the rotor 500 may float upward and be spaced apart from the inside of the third top foil 330. In addition, the first top foil 310 And the third top foil 330 is formed in a form rolled about one turn so that one end and the other end in the circumferential direction can be disposed on the upper side, and the second top foil 320 is formed in a form rolled a little more than half a turn, The rotor can be more easily lifted by air pressure, and the top foils can be formed in various ways.

The key 400 may serve to fix the top foils to the keyway 120 . The key 400 may be formed in the form of a rod having a length longer than the width and height, and is coupled to a third top foil disposed at the innermost part in the radial direction among the three top foils by welding or the like to form a single top foil and The key may be integrally formed. In addition, the key 400 may be formed in various shapes and numbers.

Here, a pitch control unit may be formed in a portion of the outer bump foil 210 or the inner bump foil 220 in which the pitches of the elastic bumps 211 and 221 are different from those of the other areas. For example, a pitch adjusting portion may be formed near a free end of the inner bump foil 220 . The pitch of the inner bump foil 220 from the 1st elastic bump 221 to the 16th elastic bump 221 is all P1 based on the bent part inserted into the keyway 120 of the bearing housing 100 and fixed. After the 17th, the pitch may be P2. (P1≠P2) At this time, only the pitch between the 17th and 18th elastic bumps may be P2, and after the 18th, it may be P1, and the 17th and subsequent pitches may be P2. All pitches between all elastic bumps may be P2. In addition, all pitches between the elastic bumps 211 of the outer bump foil 210 may be formed as P3. Thus, looking at the state in which the outer bump foil 210 and the inner bump foil 220 are assembled to the bearing housing 100, the outer bump foil 210 and the inner bump foil 220 are mutually connected to each other in the remaining parts except for the pitch adjusting part. They may be in surface contact over the entire area without being spaced apart. On the other hand, in the area where the pitch adjusting unit is formed, the outer bump foil 210 and the inner bump foil 220 may be in line contact so that most of the area may be spaced apart from each other. It may be a shape that is more inward in the radial direction than the rest of the area.

Accordingly, the air foil journal bearing of the present invention can easily adjust the inner shape of the bearing by a simple method, so that the performance of the bearing can be easily adjusted, and the manufacturability of the bump foil can not be deteriorated.

And, in the airfoil journal bearing according to the first embodiment of the present invention, the height of the elastic bumps 221 of the inner bump foil 220 formed with the pitch control part may be formed to be the same as H1, and the elasticity of the outer bump foil 210 The bumps 211 may have the same height as H2.

FIG. 6 is a conceptual diagram showing the air pressure field formed by the top foils of the air foil journal bearing according to the first embodiment of the present invention and the pitch adjusting unit when the rotor rotates.

Referring to FIG. 6 , in the air foil journal bearing according to the first embodiment of the present invention, the free end of the second top foil 320 is disposed below the center of the bearing housing 100, and the pitch adjusting unit Based on the center of the bearing housing 100, it may be disposed on the upper side. Thus, in the prior art, when the rotor rotates clockwise, negative pressure is applied near the upper left side of the rotor, but in the present invention, positive pressure is generated by the pitch control unit located near the upper left side of the rotor, so that displacement due to vibration during vibration of the rotor is reduced. can be reduced Accordingly, damping performance for vibration and driving stability may be improved.

In addition, the pitch of the elastic bumps 211 and 221 in the pitch control unit may gradually decrease or increase along the circumferential direction. For example, when P2, which is the pitch between the 17th and 18th elastic bumps 221 of the inner bump foil 220, is larger than the pitch P1 of the other elastic bumps 221 (P1<P2), including the 18th elastic bumps 221, Thereafter, it may be formed in a form in which the pitch gradually increases.

7 is a graph comparing displacement measurement values of a conventional air foil journal bearing and an air foil journal bearing according to the first embodiment of the present invention in vibration evaluation.

7, when shims are inserted into the conventional airfoil journal bearing, the experimental example A of the present invention, the experimental example B of the present invention, and the conventional airfoil journal bearing in order from left to right (bearing housing and outer bump It is the amount of displacement measured by inserting a thin plate-type shim between the foils. And, this is the case where the pitch of the pitch adjusting part of Experimental Example B is larger than that of Experimental Example A of the present invention. As shown, it can be seen that both Experimental Example A and Experimental Example B of the present invention have a smaller displacement due to vibration than the conventional air foil journal bearing. In addition, it can be seen that in Experimental Example B of the present invention, the amount of displacement due to vibration appears at almost the same level as when a shim is inserted into a conventional airfoil journal bearing.

<Example 2>

8 and 9 are cross-sectional and partially enlarged views of an air foil journal bearing according to a second embodiment of the present invention, and FIGS. 10 and 11 are outer bumps of the air foil journal bearing according to a second embodiment of the present invention. It is a conceptual diagram showing the unfolded state of the foil and inner bump foil.

As shown, the air foil journal bearing according to the second embodiment of the present invention, as shown, the air foil journal bearing according to the first embodiment of the present invention largely includes two bump foils and three top foils. It may be configured, and may further include a key and bearing housing coupled to the top foil.

The bearing housing 100, top foil and key 400 may be formed in the same manner as in the first embodiment.

The bump foil may largely include an outer bump foil 210 and an inner bump foil 220, and the outer bump foil 210 and the inner bump foil 220 are provided on the inner side of the bearing housing 100 to form a bearing housing ( 100) can be combined. In addition, the outer bump foil 210 is disposed relatively radially outward to contact the inner circumferential surface of the bearing housing 100, and the inner bump foil 220 is disposed inside the outer bump foil 210 to form an outer bump foil ( 210 , the outer bump foil 210 and the inner bump foil 220 may be coupled to the bearing housing 100 in an overlapped state. In addition, the outer bump foil 210 and the inner bump foil 220 may have ends in the circumferential direction bent outward in the radial direction, and the bent portion may be inserted into the keyway 120 of the bearing housing 100 and coupled thereto. Thus, the outer bump foil 210 and the inner bump foil 220 may be fixed to the bearing housing 100 without being rotated. In addition, the outer bump foil 210 and the inner bump foil 220 may be formed with free ends in the circumferential direction. In addition, the outer bump foil 210 and the inner bump foil 220 may each have a plurality of elastic bumps 211 and 221 formed in a radially inward convex shape, and the plurality of elastic bumps 211 and 221 may be respectively formed. It may be spaced apart at specific intervals along the circumferential direction to form a repeating form of peaks and valleys.

Here, a height adjuster may be formed in a portion of the outer bump foil 210 or the inner bump foil 220 to have different heights of the elastic bumps 211 and 221 than the rest of the area. For example, a height adjusting portion may be formed near a free end of the outer bump foil 210 . The heights of the outer bump foil 210 from the first elastic bump 211 to the 16th elastic bump 211 based on the bent portion inserted into and fixed into the keyway 120 of the bearing housing 100 may be H2. And, after the 17th, the height may be H3. (H2≠H3) At this time, the heights of all the elastic bumps 211 after the 17th may be H3, and H3 may be larger than H2. (H2<H3) In addition, all of the heights of the elastic bumps 221 of the inner bump foil 220 may be formed as H1. Thus, looking at the state in which the outer bump foil 210 and the inner bump foil 220 are assembled to the bearing housing 100, the outer bump foil 210 and the inner bump foil 220 are mutually related to each other in the remaining parts except for the height adjusting part. They may be in surface contact over the entire area without being spaced apart. On the other hand, in the area where the height adjuster is formed, the outer bump foil 210 and the inner bump foil 220 are in line contact so that most of the area may be spaced apart from each other. In the area where the height adjuster is formed, the inner bump foil 220 is It may be a shape that is more inward in the radial direction than the rest of the area.

Accordingly, the air foil journal bearing of the present invention can easily adjust the inner shape of the bearing by a simple method, so that the performance of the bearing can be easily adjusted, and the manufacturability of the bump foil can not be deteriorated.

Thus, the air foil journal bearing according to the second embodiment of the present invention is similar to the first embodiment.

In addition, in the airfoil journal bearing according to the second embodiment of the present invention, the pitch of the elastic bumps 211 of the outer bump foil 210 formed with the height adjuster may be formed to be the same as P3, and the pitch of the inner bump foil 220 The elastic bumps 221 may have the same pitch as P1.

In addition, the air foil journal bearing according to the second embodiment of the present invention can easily adjust the inner shape of the bearing as in the first embodiment, so that the performance of the bearing can be easily adjusted, and the manufacturability of the bump foil can not be reduced. .

In addition, the free end of the second top foil 320 may be disposed on the lower side with respect to the center of the bearing housing 100, and the height adjuster may be disposed on the upper side with respect to the center of the bearing housing 100. Thus, positive pressure is generated in an area near the height adjusting unit by the height adjusting unit located near the upper left side of the rotor, so that displacement due to vibration during vibration of the rotor can be reduced. Accordingly, damping performance for vibration and driving stability may be improved.

The present invention is not limited to the above embodiments, and the scope of application is diverse, and anyone with ordinary knowledge in the field to which the present invention belongs without departing from the gist of the present invention claimed in the claims Of course, various modifications are possible.

100: bearing housing
110: hollow 120: keyway
210: outer bump foil 211: elastic bump
220: inner bump foil 221: elastic bump
310: first top foil 320: second top foil
330: 3rd tower foil
400: key
500: rotor

Claims (14)

In the air foil journal bearing comprising a bump foil in which a plurality of concavo-convex elastic bumps formed in the radial direction are formed along the circumferential direction and are provided and coupled to the inside of the bearing housing,
The bump foil,
an outer bump foil disposed relatively radially outward; and
an inner bump foil disposed radially inside the outer bump foil and overlapping the outer bump foil; including,
An air foil journal bearing, characterized in that a pitch adjustment portion is formed in a portion of the outer bump foil or the inner bump foil in which the pitch of the elastic bumps is different from that of the other areas.
According to claim 1,
In the pitch adjusting unit, the outer bump foil and the inner bump foil are in line contact with each other,
The air foil journal bearing, characterized in that the outer bump foil and the inner bump foil are in surface contact in the remaining area except for the pitch adjusting part.
According to claim 1,
The air foil journal bearing, characterized in that the pitch of the elastic bumps in the pitch adjusting unit gradually decreases or increases along the circumferential direction.
According to claim 1,
a bearing housing in which the outer bump foil and the inner bump foil are provided and coupled thereto; and
a top foil provided inside the inner bump foil, formed in a circumferential direction, and coupled to the bearing housing; An air foil journal bearing made of a further comprising.
According to claim 4,
One end of each of the outer bump foil and the inner bump foil is coupled to and fixed to the bearing housing, and the other end of the outer bump foil and the inner bump foil is formed as a free end,
The air foil journal bearing, characterized in that the pitch adjusting portion is formed in a region adjacent to free ends of the outer bump foil and the inner bump foil.
According to claim 4,
The top foil,
a first top foil disposed inside the inner bump foil;
a second top foil disposed inside the first top foil; and
a third top foil disposed inside the second top foil; including,
An air foil journal bearing, characterized in that the first top foil, the second top foil and the third top foil overlap each other.
According to claim 6,
The air foil journal bearing, characterized in that the free end of the second top foil is disposed on the lower side with respect to the center of the bearing housing, and the pitch adjusting unit is disposed on the upper side with respect to the center of the bearing housing.
In the air foil journal bearing comprising a bump foil in which a plurality of concavo-convex elastic bumps formed in the radial direction are formed along the circumferential direction and are provided and coupled to the inside of the bearing housing,
The bump foil,
an outer bump foil disposed relatively radially outward; and
an inner bump foil disposed radially inside the outer bump foil and overlapping the outer bump foil; including,
An air foil journal bearing, characterized in that a height adjuster is formed in a portion of at least one of the outer bump foil and the inner bump foil, wherein the height of the elastic bumps is different from the rest of the area.
According to claim 8,
In the height adjuster, the outer bump foil and the inner bump foil are in line contact with each other,
The air foil journal bearing, characterized in that the outer bump foil and the inner bump foil are in surface contact in the remaining area except for the height adjusting portion.
According to claim 8,
Air foil journal bearings, characterized in that the pitch of the elastic bumps in the height adjustment unit is the same as each other.
According to claim 8,
a bearing housing in which the outer bump foil and the inner bump foil are provided and coupled thereto; and
a top foil provided inside the inner bump foil, formed in a circumferential direction, and coupled to the bearing housing; An air foil journal bearing made of a further comprising.
According to claim 11,
One end of each of the outer bump foil and the inner bump foil is coupled to and fixed to the bearing housing, and the other end of the outer bump foil and the inner bump foil is formed as a free end,
The air foil journal bearing, characterized in that the height adjusting portion is formed in a region adjacent to free ends of the outer bump foil and the inner bump foil.
According to claim 11,
The top foil,
a first top foil disposed inside the inner bump foil;
a second top foil disposed inside the first top foil; and
a third top foil disposed inside the second top foil; including,
An air foil journal bearing, characterized in that the first top foil, the second top foil and the third top foil overlap each other.
According to claim 13,
The air foil journal bearing, characterized in that the free end of the second top foil is disposed on the lower side with respect to the center of the bearing housing, and the height adjuster is disposed on the upper side with respect to the center of the bearing housing.

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