JPH08261232A - Squeezed film dumper bearing - Google Patents

Abstract

PURPOSE: To prevent cutting of an oil film due to a big whirling force by bringing projections in parallel with the inner and outer peripheral axes of a concentric spring into contact with a bearing outer periphery and a bearing case supporting surface and supplying oil to a recess formed between the projections. CONSTITUTION: The projections 5a and 5b of a concentric spring 3 are respectively brought into contact with a supporting surface 13 and the outer periphery of a bearing metal 2 and the bearing metal 2 is supported so as to be concentric with the supporting surface 13 of a bearing case 4. A plurality of projections are provided at equal intervals in the circumferential directions of both ends of the supporting surface 13 in order to hold the concentric spring 3 in an axial direction without being moved. Lubricating oil flows through an oil supply passage 9 into a space 12a and its part is supplied through the recesses 6 of the inner and outer surfaces of the concentric spring 3 to a space 12b. A part of the lubricating oil of the space 12a and the lubricating oil of the space 12b flow through an oil supply passage 11 into the inner surface of the bearing metal 2, forming an oil film between this and a rotary shaft 1. Since vibrations are reduced by this oil film equivalent to the depth of the recess 6 and the rigidity of the concentric spring is large, cutting of the oil film is prevented even when shaking around of the shaft is large.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing for supporting a high speed rotating shaft such as a centrifugal compressor, and more particularly to a squeeze film damper bearing.

[0002]

2. Description of the Related Art A squeeze film damper bearing is a bearing in which a fluid film is formed between a bearing that supports a rotating shaft and a fixed surface, and the bearing is supported by the pressure of the fluid film. It is extremely effective as a bearing for turbo compressors and turbochargers.

A typical example of such a squeeze film damper bearing is shown in Japanese Patent Application Laid-Open No. 58-109718. In this example, a gap is provided between the fixed bearing surface and the outside of the outer ring retainer of the rolling bearing, and a film damper oil film is formed by refueling the gap, and the outer ring retainer is fixed parallel to the shaft from the fixed side. It is supported by a large number of bolts extending so as to surround it, and the bolts act as springs. In this way, the bearing is supported by the spring and the oil film provided in parallel with the spring to form a squeeze film damper bearing.

However, the structure described above is difficult to assemble with high precision, is therefore expensive, requires a large space in the axial direction, and is difficult to apply to a small rotating machine having a limited space. . In order to solve this problem, the applicant of the present patent application has previously filed an application of Japanese Utility Model Application No. 60-169158 (actual fair number 3-39618). FIG. 3 is a sectional view taken in a direction perpendicular to the axis of the squeeze film bearing of the above application.

As shown in FIG. 3, in the squeeze film bearing, the outer ring of the rolling bearing b mounted on the rotary shaft a is fitted in the outer ring support ring d, and the outer ring support ring d and the bearing surface of the bearing case c covering it. Cylindrical thin plate f between e
Has been inserted. On the outer surface and inner surface of the thin plate f, recesses g and h formed by etching are arranged at equal intervals in the circumferential direction and staggered. Therefore, the convex portions i and j are formed between the adjacent concave portions g and h, and the convex portion j is in contact with the outer ring support ring d and the convex portion i is in contact with the bearing surface e. The recesses g and h are formed over the entire width of the thin plate f. An oil passage (not shown) for supplying oil so as to generate a predetermined oil film pressure is provided in communication in the recesses g and h.

[0006]

However, in the above-described squeeze film bearing, the rigidity of the thin plate forming the film damper is small, so that the direction perpendicular to the axis (that is, the radial direction).
The whirling force easily causes the surface of the recess g or h to directly abut the bearing surface e of the bearing case or the outer surface of the outer ring support ring d, and the oil film is cut off at that portion, and the performance as a film damper deteriorates. I will end up.

Further, since the thin plate f is integrally formed in a cylindrical shape, the protrusions i and j must be brought into close contact with the outer ring support ring d and the bearing surface e of the bearing case with high precision unless the manufacturing precision is increased so much. Are difficult to manufacture, and therefore the production cost is high.

The present invention has been devised in view of the above problems, and an object of the present invention is to provide a squeeze film damper bearing capable of effectively damping the whirling of the shaft and being inexpensive to manufacture.

[0009]

In order to achieve the above object, the squeeze film damper bearing of the present invention has rigidity between the outer circumference of the bearing metal supporting the rotating shaft and the bearing surface of the bearing case inner surface covering the bearing metal. , Which has a large concentric spring, has a circular arc shape in which a cylinder is equally divided into a plurality of parts in the circumferential direction, and projections parallel to the axis are formed on the outer circumference of the spring at both ends and the middle in the circumferential direction. The protrusions are arranged at equal intervals on the inner periphery of the spring, and the protrusions on the outer periphery are provided with protrusions parallel to the shaft so as to be located at the approximate center of the Sugano circumferential direction. And an oil supply passage for supplying oil so as to generate a predetermined oil film pressure, are connected to the concave portions formed between the projections.

[0010]

The bearing is supported by the bearing surface of the bearing case via the projection provided on the concentric spring. Since the concentric spring has a high rigidity, even if a whirling force is applied to the bearing, the surface of the recess formed between the projections does not come into contact with the bearing surface and the oil film is not broken. Further, since the concentric spring has an arc shape divided in the circumferential direction, it is slightly deformed by being pressed by the bearing casing and is formed between the outer circumference of the bearing metal and the bearing surface of the inner surface of the bearing case covering the bearing metal. Since the shape of the gap is adapted, the bearing can be accurately supported with good adhesion to the protrusions even if the manufacturing accuracy is somewhat low.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 is a front sectional view of a squeeze film damper bearing of the present invention, and FIG. 2 is a sectional view taken along the arrow A in FIG.

In the figure, 1 is a rotary shaft, 2 is a bearing metal, and two semicircular ones are used in combination in the upper and lower directions. Reference numeral 3 is a concentric spring, and two semi-circular springs are used by combining them vertically. Outside the concentric spring 3, projections 5a parallel to the axis are provided at both ends in the circumferential direction and at the central portion in the circumferential direction. Further, inside the concentric spring 3, there is provided a projection 5b parallel to the axis in the direction of 45 ° from the horizontal. A recess 6 is formed between the protrusions. The concentric spring is manufactured as follows. That is, when the portions of the inner and outer surfaces of the cylindrical body which correspond to the protrusions are masked and the remaining portions are removed by etching, the etched portions become the recesses 6 and the masked portions remain as the protrusions 5. After that, it may pass through the central portion of the outer protrusion 5a and be cut along a plane including the axis. The depth of the recess 6 may be about 0.1 to 0.2 mm.

A bearing case 4 comprises an upper bearing case 4a and a lower bearing case 4b. Upper and lower bearing cases 4
A and 4b are fastened by through bolts (not shown) inserted into the bolt holes 7. The bearing case 4 has a U-shaped side cross-section, and a cylindrical bearing surface 13 is formed on the inner surface. When the bearing is assembled, the concentric spring 3
Of the bearing metal 2 to the bearing surface 13 and the protrusion 5b to the bearing surface of the bearing metal 2, respectively.
It is supported so as to be concentric with the bearing surface 13 of. 8 is a bearing surface 1 for holding the concentric spring 3 so as not to move in the axial direction.
A plurality of protrusions are provided at both end portions of No. 3 at equal intervals in the circumferential direction. 9 and 11 are oil supply passages and 10 is an O-ring. 12
Reference characters a and 12b are spaces formed on both sides of the concentric spring 3.

Next, the operation of this embodiment will be described. The lubricating oil flows into the one space 12a through the oil supply passage 9. The pressure of the lubricating oil may be 2-3 kg / cm ² . A part of the lubricating oil from the space 12a is a recess 6 formed on the inner and outer surfaces of the concentric spring 3.
Through to the other space 12b. A part of the lubricating oil flowing into the space 12a and the lubricating oil flowing into the space 12b flow into the inner surface of the bearing metal 2 through the oil supply passage 11 and form a lubricating oil film with the rotating shaft 1. At this time, the oil supply passage 11
As shown in the figure, if the space closer to the space 12a is made thinner and the space closer to the space 12b is made thicker, the amounts flowing in both spaces are balanced. Since the oil film (squeeze film) corresponding to the depth of the recess 6 is formed on the inner and outer surfaces of the concentric spring 3, the vibration generated in the bearing is damped. Since the concentric spring has a large rigidity, the surface of the recess 6 does not directly contact the surface of the bearing metal 2 or the surface of the bearing surface 13 and the oil film is not broken even when the swinging force of the shaft is large.

The concentric spring 3 preferably has a spring constant of about 10 ⁴ kg / cm when a force is applied to the inner protrusion 5b with the outer protrusion 5a as a fulcrum. The spring constant depends on the thickness and width of the spring, the distance between the protrusions, and the like.

Since the concentric spring 3 has a semicircular shape as shown in FIG. 4, it is slightly deformed by being pressed by the bearing casing 4 and the outer circumference of the bearing metal 2 and the bearing surface 13 of the bearing case. Since it conforms to the shape of the gap formed between the two, even if the manufacturing accuracy is somewhat low, the adhesion with the protrusions 5a and 5b is good and the bearing can be supported with high accuracy.

The present invention is not limited to the embodiments described above, but various modifications can be made within the scope of the claims. For example, the bearings may be rolling bearings as shown in FIG. 3 instead of sliding bearings. In this case, the outer ring retainer is fitted onto the outer ring of the rolling bearing, and the outside of the outer ring retainer is concentric with the spring 3.
Will be supported by.

[0018]

As described above, the squeeze film damper bearing of the present invention has the following effects because it has high rigidity and uses the concentric springs divided into a plurality of pieces in the circumferential direction. (1) The oil film is not broken even when a large whirling force is applied, and the vibration damping function of the film damper is always maintained. (2) Even if the manufacturing precision is somewhat low, the adhesion with the concentric spring is good, so the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a front sectional view of a squeeze film damper bearing of the present invention.

FIG. 2 is a sectional view taken along the arrow A in FIG.

FIG. 3 is a front sectional view of a conventional squeeze film bearing.

FIG. 4 is a perspective view of a concentric spring.

[Explanation of symbols]

 1 rotating shaft 2 bearing metal 3 concentric spring 4 bearing casing 5 protrusion 6 recess

Claims (5)

[Claims] 1. A concentric spring having high rigidity is inserted between an outer periphery of a bearing metal supporting a rotating shaft and a bearing surface of an inner surface of a bearing case covering the bearing metal, and the concentric spring is a cylinder. It has a circular arc shape equally divided into a plurality of parts in the circumferential direction, and projections parallel to the axis are provided on the outer circumference of the spring at equal intervals at both ends and the middle part in the circumferential direction. Protrusions parallel to the shaft are provided so as to be located approximately in the center between the protrusions in the circumferential direction, and each protrusion abuts on the outer periphery of the bearing and the bearing surface of the bearing case, and a predetermined portion is formed in a recess formed between the protrusions. The squeeze film damper bearing is characterized in that an oil supply passage for supplying oil to generate the oil film pressure is connected. 2. The squeeze film damper bearing according to claim 1, wherein the concentric spring has a semicircular shape. 3. The squeeze film damper bearing according to claim 1, wherein the recess is formed by etching. 4. The squeeze film damper bearing according to claim 1, wherein the bearing is a slide bearing formed by being divided into two in the circumferential direction. 5. The squeeze film damper bearing according to claim 1, wherein the bearing is a rolling bearing.