KR20230128718A - Air foil journal bearing - Google Patents

Abstract

The present invention relates to airfoil journal bearings. It provides a receiving space of a certain inner diameter, a bearing housing having a concealed groove formed on an outer circumferential surface, and a side passage opening the receiving space toward the concealed groove side; Built in the accommodating space of the bearing housing, in line contact with the inner circumferential surface of the accommodating space, elastically deformable elastic body, integral with one end of the elastic body, having a first extension tab accommodated in the concealed groove through the side passage a bump foil; A foil body accommodated inside the bump foil and in surface contact with the bump foil, a second extension tab integrally formed at one end of the foil body and accommodated in a concealed groove through a side passage, overlapping the first extension tab a top foil; A fixing part fixing the overlapping first extension tab and the second extension tab in the concealing groove is included.
Since the airfoil journal bearing of the present invention formed as described above does not cause abrasion at the contact portion between the bump foil and the bearing housing, there is no need for maintenance on the bearing housing even when used for a long time, and it always maintains the best condition. . In addition, since the coupling of the bump foil and the top foil to the bearing housing is implemented in a prefabricated manner, periodic or non-periodic replacement of the bump foil and top foil is possible, which is advantageous in maintenance.

Description

Air foil journal bearing {Air foil journal bearing}

The present invention relates to an airfoil journal bearing, and more particularly, to an airfoil journal bearing, which does not require abrasion of the bearing housing due to bump foils, requires little maintenance of the bearing housing, and maintains the best condition even after long use. It's about journal bearings.

Airfoil bearings, which are widely used in various turbo machines, have the basic principle of allowing the shaft to be lifted by the force of air within the bearing housing by guiding the compressed air generated during shaft rotation into the space between the shaft and the bearing housing. have

For example, in the case of a gas turbine engine with an airfoil bearing, the air compressed in the compressor is mainly used for fuel combustion, and the remaining compressed air is supplied to the airfoil bearing to support the shaft of the compressor or turbine. to drive the bearings.

Such an airfoil bearing is suitable for supporting the shaft of a rotating body rotating at high speed, and can be used as a bearing for a high-speed turbo machine operating at 50,000 rpm to 150,000 rpm, for example. Moreover, airfoil bearings are clean because they do not require a lubrication system, and have good load bearing capacity because the area supporting the shaft is wider than other types of bearings.

As a background technology of this related invention, a journal foil air bearing has been disclosed through Korean Patent Registration No. 10-1068542.

The disclosed journal foil air bearing includes a bearing housing having a hollow in which a rotor is disposed; bump foils spaced apart from each other along the inner circumferential surface of the hollow of the bearing housing and installed at least two; It is disposed along the top of two or more bump foils and includes a top foil installed one along the circumferential direction; When the rotor rotates at high speed, the top foil is deformed outwardly in a lobe form at a place where the bump foils are spaced apart from each other.

However, the conventional air bearing described above has a disadvantage in that the top foil and the bump foil are fixed to the bearing housing by welding. That is, the top foil and the bump foil are fixed to the spacer block of the bearing housing by spot welding. Since it is fixed by welding, it is of course impossible to replace the top foil and the bump foil separately.

In addition, when cracks occur on the welded portion due to micro-vibration generated during use and the welded portion is finally broken, the top foil and bump foil are separated, resulting in a large-scale accident and destruction of the equipment with built-in air bearings. It can be.

In addition to this, there is also a problem that the contact portion between the bump foil and the bearing housing can be easily worn. The corner of the bump foil rubs against the inner circumferential surface of the bearing housing, and the friction part is cut and eaten. Of course, if the wear is severe, the function as a bearing cannot be properly performed.

Korean Patent Registration No. 10-1068542 (Journal Foil Air Bearing)

The present invention was created to solve the above problems, and maintenance of the bearing housing is not required even when used for a long time, it is always maintained in the best condition, and the bump foil and top foil can be periodically or non-periodically replaced. It is an object to provide an advantageous, airfoil journal bearing.

The airfoil journal bearing of the present invention as a means of solving the problems for achieving the above object takes the shape of a ring and provides an accommodation space of a certain inner diameter, a concealed groove is formed on the outer circumferential surface, and the accommodation space is opened toward the concealed groove a bearing housing having a side passage to; It is embedded in the accommodating space of the bearing housing in a rolled state, and is in line contact with the inner circumferential surface of the accommodating space, elastically deformable by external force, integral with one end of the elastic body, concealed groove through the side passage a bump foil having a first extension tab accommodated therein; A foil body accommodated inside the bump foil in a rolled state and in surface contact with the bump foil, formed integrally with one end of the foil body and accommodated in a concealed groove through a side passage, and overlapping the first extension tab. a top foil having two extension tabs; A fixing part fixing the overlapping first extension tab and the second extension tab in the concealing groove is included.

In addition, a tangential plane portion extending in a tangential direction of a circumferential circle of an inner circumferential surface of the accommodation space is formed inside the concealing groove, and the first extension tab and the second extension tab are detachably fixed to the tangential plane portion in an overlapping state. do.

In addition, the bump foil is obtained by pressing a metal plate having a certain width and length, and the elastic body has a constant pitch interval in the longitudinal direction and is in line contact with the inner circumferential surface of the accommodating space. and has a close-contact portion that is positioned and comes into surface contact with the foil body.

Further, the elastic body takes a predetermined cross-sectional shape in the width direction, and the curved portion is in line contact with the inner circumferential surface of the accommodation space, and opens when the contact portion is pressed by an external force.

In addition, the resilient body has a predetermined cross-sectional shape in the width direction, and the curved portion is in line contact with the inner circumferential surface of the accommodation space, and when the contact portion is pressed by an external force, it collapses.

In addition, the elastic body of the bump foil; A plurality of adhesion members spaced apart at regular intervals, parallel to each other, and face-to-face with the top foil, located between each adhesion member, assembled to be decomposable for the adhesion member, in line contact with the inner circumferential surface of the accommodation space, and by external force It is configured to include a plurality of elastically deformable elastic curved surface members.

In addition, the elastic curved surface member is slidably fitted to the close contact member.

Since the airfoil journal bearing of the present invention formed as described above does not cause abrasion at the contact portion between the bump foil and the bearing housing, there is no need for maintenance on the bearing housing even when used for a long time, and it always maintains the best condition. .

In addition, since the coupling of the bump foil and the top foil to the bearing housing is implemented in a prefabricated manner, periodic or non-periodic replacement of the bump foil and top foil is possible, which is advantageous in maintenance.

1 is a cutaway perspective view of an air blower to which an airfoil journal bearing is applied according to an embodiment of the present invention.
2 is an exploded perspective view of the air blower shown in FIG. 1;
FIG. 3 is a view showing the shaft and journal bearing of FIG. 1 separately.
4 is a perspective view of a journal bearing according to an embodiment of the present invention.
5 is a front view of the journal bearing shown in FIG. 4;
6 is an exploded perspective view of the journal bearing shown in FIG. 4;
7 is an exploded cutaway perspective view of the journal bearing of FIG. 4 .
8A and 8B are diagrams for explaining the action of a bump foil in a journal bearing according to an embodiment of the present invention.
9 is a front view illustrating a modified example of a journal bearing according to an embodiment of the present invention.
10 is a front view for explaining another modified example of a journal bearing according to an embodiment of the present invention.

Hereinafter, one embodiment according to the present invention will be described in more detail with reference to the accompanying drawings.

The journal bearing of the present invention is applicable to various turbo machines. A turbo machine is a term that encompasses mechanical equipment with built-in high-speed rotating shafts. In this embodiment to be described later, the air blower 10 will be described as an example as a turbo machine.

1 is an exploded perspective view of an air blower to which an airfoil journal bearing is applied according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view of the air blower shown in FIG. 1 . 3 is a view separately showing the shaft and the journal bearing of FIG. 1 .

As shown, the motor 11 is built into the main body 18 of the air blower 10, and the shaft 13 outputting the rotational force of the motor 11 is supported by two journal bearings 30 there is. The journal bearing 30 rotatably supports the shaft 13 while being accommodated and fixed to the main body 18 .

In addition, an impeller 17 is fixed to one end of the shaft 13. The impeller 17 is built into the impeller casing 15 and rotates at high speed when the motor 11 is operated to pump air.

The two journal bearings 30 have the same configuration, and have basic configurations of a bearing housing 31, a bump foil 37, and a top foil 35. In particular, the bump foil 37 and the top foil 35 are detachably mounted to the bearing housing 31 . In other words, it is not completely fixed by welding, but can be separated if necessary.

4 is a perspective view of a journal bearing according to an embodiment of the present invention, and FIG. 5 is a front view of the journal bearing shown in FIG. 4 . Also, it is an exploded perspective view of the journal bearing, and FIG. 7 is an exploded perspective view of the journal bearing of FIG. 4 with a partial cutout. 8A and 8B are diagrams for explaining an action of a bump foil in a journal bearing according to an embodiment of the present invention.

As shown, the airfoil journal bearing 30 according to this embodiment includes a bearing housing 31, two bump foils 37, a top foil 35, and a fixing screw 40 as a fixing part. .

The bearing housing 31 is a ring-shaped member providing a receiving space 31b of a certain inner diameter. The bearing housing 31 may be made of aluminum. In addition, two concealed grooves 31k are formed outside the bearing housing 31 . The concealed groove 31k is a portion to which first and second extension tabs 37e and 35c are coupled, and communicates with the accommodation space 31b through the side passage 31c. The side passage 31 is a hole through which the first and second extension tabs 37e and 35c pass.

In addition, the bottom surface of the concealing groove 31k is a tangential flat portion 31e, which is in close contact with the second extension tab 35c. The tangential flat portion 31e is a flat surface extending in the tangential direction of the circumferential circle (S in Fig. 5) of the inner circumferential surface 31a of the accommodating space 31b. In other words, the imaginary plane including the tangent plane portion 31e coincides with the tangent to the circle S.

The reason why the tangential plane portion 31e coincides with the tangential line as described above is to more easily push the first and second extension tabs 37e and 35c toward the concealed groove 31k. That is, in a state where the bump foil 37 and the top foil 35 are wound round and inserted into the accommodating space 31b, only by rotating them in the direction of the arrow a, the first and second extension tabs 37e and 35c are It automatically passes through the side passage 31c and falls in the direction of arrow b, considering the simplicity of this assembly.

In addition, female screw holes 31g are formed on both tangential plane portions 31e. The female screw hole 31g is a groove into which the fixing screw 40 is screwed.

The bump foil 37 is obtained by pressing a metal plate having a certain thickness, and is composed of an elastic body 37d and a first extension tab 37e.

The elastic body 37d takes the shape of a substantially rectangular plate, and has a plurality of parabolic curved portions 37a and contact portions 37c. The contact portion 37c is a portion that adheres to the outer circumferential surface of the foil body 35a of the top foil 35. In addition, the parabolic curved surface portion 37a protrudes convexly toward the inner circumferential surface 31a of the bearing housing 31, and as shown in FIG. 5, it is a portion that makes linear contact with the inner circumferential surface 31a.

The parabolic curved surface portion 37a is integrally formed between the two contact portions 37c. Similarly, the contact portion 37c is integrally formed between the two parabolic curved surface portions 37a. The parabolic curved portion 37a has a parabolic cross-sectional shape, and is completely open in the direction of the top foil 35, as shown in FIG. 8A.

The parabolic curved surface portions 37a have a constant pitch interval in the longitudinal direction. The term "longitudinal direction" means the longitudinal direction when the elastic body 37d is flatly unfolded (circumferential direction when rolled). In addition, the cross-sectional shape of the elastic body 37d in the width direction is the same. The width direction is a direction orthogonal to the length direction.

The first extension tab 37e is a rectangular plate integrally formed with one end of the elastic body, and as described above, passes through the side passage 31c and is accommodated in the concealed groove 31k by the fixing screw 40. fixed by To this end, a screw hole 37g is formed in the first extension tab 37e.

Meanwhile, two bump foils 37 are embedded in the journal bearing 30 of this embodiment. That is, as shown in FIG. 6, the two are accommodated in the bearing housing 31 in a connected state side by side. In particular, the parabolic curved surface portions 37a of the bump foils 37 on both sides are shifted by half pitch. In other words, in the drawing of FIG. 6 , the parabolic curved portion 37a is located on the right side of the close contact portion 37c of the left bump foil 37. This arrangement structure is to balance the support for the shaft 13.

The two bump foils 37 having the above configuration are mounted on the bearing housing 31 in a rolled state. At this time, the parabolic curved surface portion 37a of the elastic body 37d makes linear contact with the inner circumferential surface 31a of the bearing housing.

The top foil 35 is composed of a foil body 35a and two second extension tabs 35c. The top foil 35 is also manufactured by pressing a metal plate having a certain thickness.

The foil body 35a is accommodated inside the bump foil 37 in a rolled state, and the outer circumferential surface faces the contact portion 37c. The foil body 35a transfers the load generated when the shaft 13 rotates at high speed to the bump foil 37 .

As shown in Figs. 8A and 8B, the bump foil 37 is elastically deformed by the top foil 35 being pressed in the direction of arrow F. That is, the parabolic curved surface portion 37a elastically spreads and absorbs vibration. When the force applied to the top foil 35 is removed, the parabolic curved surface portion 37a is elastically restored to its original state.

Although the parabolic curved surface portion 37a elastically deforms and absorbs vibration, it is not accompanied by friction with the bearing housing 31, and since the shape of the parabolic curved surface portion 37a itself is formed round, the bearing housing inner circumferential surface 31a wear does not occur.

The second extension tab 35c passes through the side passage 31c and is accommodated in the concealed groove 31k. The second extension tab 35c is interposed between the first extension tab 37e and the tangential plane portion 31e. A screw hole 35e is also formed in the second extension tab 35c. The second extension tab 35c is fixed to the inside of the concealed groove 31k through the fixing screw 40 while overlapping the first extension tab 37e.

9 is a front view showing a modified example of the journal bearing 30 according to an embodiment of the present invention.

Hereinafter, the same reference numerals as the above reference numerals indicate the same members having the same functions.

The elastic body 37d in the bump foil 37 shown in FIG. 9 is composed of a contact portion 37c and a cylindrical curved portion 37k. The cylindrical curved portion 37k is a portion in line contact with the inner circumferential surface 31a of the bearing housing 31 . Although the cylindrical curved portion 37k is open to the bump foil 37 side, it takes a constricted shape. In other words, the maximum diameter D of the inside of the cylindrical curved portion 37k is relatively large compared to the distance W at the point where the cylindrical curved portion 37k and the contact portion 37c meet.

The cylindrical curved portion 37k is elastically deformed in a constriction direction when a pressing force in the direction of arrow P is applied, and absorbs vibration. Of course, when the pressing force in the direction of the arrow P is removed, it is elastically restored to the initial state.

10 is a front view for explaining another modified example of a journal bearing according to an embodiment of the present invention.

The elastic body 52 of the bump foil 50 shown in FIG. 10 has a prefabricated structure. That is, a plurality of close contact members 51 and elastic curved surface members 53 are mutually fitted and assembled.

The adhesive member 51 is a portion that faces the top foil 35 and has a fitting groove 51c at an end in the direction of the elastic curved member 53 . Fitting groove (51c) is a groove formed by bending the end of the close contact member (51).

In addition, the elastic curved surface member 53 is a member that is curved in a substantially U-shape and has a predetermined cross-sectional shape in the longitudinal direction (width direction of the elastic body), and is in line contact with the inner circumferential surface 31a of the bearing housing 31. The elastic curved surface member 53 can be elastically deformed.

In addition, a hook 53a is formed at an end of the elastic curved member 53 . The hook 53a is also made by bending the elastic curved surface member 53. The engaging hook 53a is inserted into the fitting groove 51c in a sliding direction. That is, in a state in which the engaging hook 53a is aligned with one end of the fitting groove 51c, the assembly is performed by sliding in the longitudinal direction of the fitting groove.

As described above, by implementing the close contact member 51 and the elastic curved member 53 in an assembly type, the close contact member 51 or the elastic curved member 53 can be selectively replaced. For example, replacing only damaged parts.

Furthermore, a plurality of elastic curved surface members 53 having different elastic forces may be provided, and the elastic curved surface members 53 may be replaced according to the required load of the bearing. For example, an elastic curved surface member having an optimal elastic force can be mounted and used in its place, except for the elastic curved surface member used.

In the above, the present invention has been described in detail through specific embodiments, but the present invention is not limited to the above embodiments, and various modifications are possible by those skilled in the art within the scope of the technical idea of the present invention.

10: air blower 11: motor 13: shaft
15: impeller casing 17: impeller 18: main body
30: journal bearing 31: bearing housing 31a: inner circumference
31b: accommodation space 31c: side passage 31e: tangent plane
31g: female screw hole 31k: concealed groove 35: top foil
35a: foil body 35c: second extension tab 35e: screw hole
37: bump foil 37a: parabolic curved surface portion 37c: contact portion
37d: elastic body 37e: first extension tab 37g: screw hole
37k: cylindrical curved portion 40: fixing screw 50: bump foil
51: adhesion member 51c: fitting groove 52: elastic body
53: elastic curved surface member 53a: hook

Claims (7)

a bearing housing in the shape of a ring, providing an accommodation space of a predetermined inner diameter, having a concealed groove formed on an outer circumference thereof, and having a side passage opening the accommodation space toward the concealed groove side;
It is embedded in the accommodating space of the bearing housing in a rolled state, and is in line contact with the inner circumferential surface of the accommodating space, elastically deformable by external force, integral with one end of the elastic body, concealed groove through the side passage a bump foil having a first extension tab accommodated therein;
A foil body accommodated inside the bump foil in a rolled state and in surface contact with the bump foil, formed integrally with one end of the foil body and accommodated in a concealed groove through a side passage, and overlapping the first extension tab. a top foil having two extension tabs;
Including a fixing part for fixing the overlapping first extension tab and the second extension tab in the concealing groove,
Airfoil journal bearings. According to claim 1,
Inside the concealed groove,
A tangential plane portion extending in the tangential direction of the circumferential circle of the inner circumferential surface of the accommodation space is formed,
The first extension tab and the second extension tab are detachably fixed to the tangential plane portion in an overlapping state.
Airfoil journal bearings. According to claim 1,
The bump foil is obtained by pressing a metal plate having a certain width and length,
The elastic body,
Having a curved portion having a predetermined pitch interval in the longitudinal direction and in line contact with the inner circumferential surface of the accommodation space, and a close contact portion located between each curved portion and in surface contact with the fabric body,
Airfoil journal bearings. According to claim 3,
The resilient body takes a certain cross-sectional shape in the width direction,
The curved portion is in line contact with the inner circumferential surface of the accommodation space, and opens when the close contact portion is pressed by an external force.
Airfoil journal bearings. According to claim 3,
The elastic body has a certain cross-sectional shape in the width direction,
The curved portion, in a state of line contact with the inner circumferential surface of the accommodation space, is compressed when the close contact portion is pressed by an external force.
Airfoil journal bearings. According to claim 1,
The elastic body of the bump foil;
A plurality of adhesion members spaced apart at a predetermined interval, parallel to each other, and interviewing the top foil;
Located between each contact member, assembled to be decomposable for the contact member, in line contact with the inner circumferential surface of the accommodation space, and composed of a plurality of elastic curved surface members that can be elastically deformed by external force,
Airfoil journal bearings. According to claim 6,
The elastic curved surface member,
Fitting and coupling to be able to slide to the close member,
Airfoil journal bearings.

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