DE202021106586U1 - Bearing arrangement for a rotating shaft - Google Patents

Abstract

Bearing arrangement (100) for a rotating shaft (9), in particular for a gas turbine shaft, comprising a bearing inner ring (3), a bearing outer ring designed as a bearing damping ring (5), rolling bodies (7) which are located between the bearing inner ring (3) and the bearing damping ring (5 ) are arranged, a bearing housing (11) and a fluid (13) for bearing damping arranged between an outside of the bearing damping ring (5) and an outside of the radially opposite inside of the bearing housing (11), the bearing damping ring (5) for hydraulic bearing damping by means of the fluid (13), and wherein the bearing damping ring (5) has a stepped outer profile, with a first step (15) having a smaller outer radius (R1) compared to a second step (17) with a larger outer radius (R2) of the bearing damping ring (5 ) has, and wherein the first stage (15) is arranged in a groove-like manner between two axially (a) adjacent second stages (17), and the axial replacement elongation of the two adjacent second stages (17) corresponds at least to the axial extent of the first stage (15).

Description

The present invention relates to a bearing arrangement for a rotating shaft, in particular for a gas turbine shaft, comprising a bearing inner ring, a bearing damping ring, rolling bodies, a bearing housing and a fluid for bearing damping.

In the case of gas turbines, which are used as engines in aircraft, for example, or in other devices with a rotating shaft, resonances can occur under load, which can lead to damage to the gas turbine, for example. Accordingly, the occurrence of such resonance vibrations should be avoided, specifically preferably over the entire operating range of the gas turbine. A known possibility from the prior art are damping systems in the area of the shaft bearing. As a rule, however, these damping systems cannot compensate for or dampen very strong imbalances.

So-called "squeeze film damping systems" are often used to dampen these systems. Most aircraft engines have one or more of these systems. They are constructed in such a way that there is an oil-filled, circumferential radial gap between the bearing housing and the bearing outer ring, which acts as a vibration-dampening, viscous damper (liquid damper). In the case of strong rotor imbalances, e.g. B. due to blade fracture, the viscous damping of this arrangement is no longer sufficient according to the prior art, so that there are strong radial relative movements. The mostly cylindrical shape of these damping systems is not optimized for these strong imbalances.

An object of the present invention is to propose a bearing arrangement for a rotating shaft which can also dampen strong imbalances.

The object according to the invention is achieved by a bearing arrangement having the features of claim 1.

According to the invention, a bearing arrangement for a rotating shaft, in particular for a gas turbine shaft, is proposed which has a bearing inner ring, a bearing outer ring designed as a bearing damping ring, rolling elements which are arranged between the bearing inner ring and the bearing damping ring, a bearing housing and a bearing between an outside of the bearing damping ring and an outside of the comprises radially opposite inside of the bearing housing arranged fluid for bearing damping. The fluid can in particular be a highly viscous oil. The bearing damping ring is designed for hydraulic bearing damping by means of the fluid. The bearing damping ring has a stepped outer profile. A first stage of the outer profile has a smaller outer radius compared to a second stage with a larger outer radius of the bearing damping ring. The first stage is arranged in the form of a groove between two axially adjacent second stages. The shape of the groove can be designed as an elongate depression with a cylindrical shape or can be referred to as such. The axial extent of the two adjacent second stages corresponds at least to the axial extent of the first stage.

Advantageous further developments of the present invention are the subject matter of subclaims and embodiments.

Exemplary embodiments according to the invention can have one or more of the features mentioned below in any combination, provided that one or the specific combination is not evidently technically impossible for a person skilled in the art. The subject matter of the subclaims also each specify exemplary embodiments according to the invention.

In all statements made above and below, the use of the expression “can be” or “can have” etc. is to be understood as synonymous with “is preferably” or “has preferably” etc. and is intended to explain exemplary embodiments according to the invention.

Whenever alternatives with "and/or" are introduced herein, the person skilled in the art understands the "or" contained therein preferably as "either or" and preferably not as "and".

Embodiments mentioned herein are to be understood as inventive, purely exemplary embodiments of the present invention, which are not to be understood as limiting.

In some embodiments according to the invention, the first stage is arranged radially to the rolling elements. In this arrangement, the wall thickness of the bearing outer ring designed as a bearing damping ring can be significantly less than the axially adjacent wall thickness of the bearing damping ring with the second stage. At the same time, the fluid volume in the radially adjoining intermediate space toward the bearing housing is greater than the fluid volume radially toward the second stage. As a result, this bearing area, which is arranged radially to the rolling bodies, can advantageously have a damping effect for particularly high imbalances.

In some embodiments according to the invention, the fluid is an oil, in particular a highly viscous oil. A highly viscous oil can advantageously have a particularly strong damping effect on vibrations and imbalances.

In some embodiments of the present invention, the first stage groove shape is rectangular or trapezoidal. These groove shapes can often be easily produced by standardizing the geometries.

In some embodiments of the present invention, the first stage groove shape has a round, oval, or other cross-sectional shape. These groove shapes can have special damping properties. Depending on the vibration patterns and imbalances to be expected, individual cross-sectional shapes can advantageously be implemented constructively.

In some embodiments according to the invention, the first step and/or the second step has grooves which are formed essentially in the axial direction. Grooves can additionally dampen vibrations and/or imbalances. Depending on the shape, size and number of grooves, the damping can be advantageously influenced.

In some embodiments according to the invention, the radial distance between the radially outer surface of the second stage and the radially opposite inner side of the bearing housing is between 0.05 mm and 0.12 mm. The radial distance can be 0.1 mm in particular. The fluid volume in this space correlates with the distance. Therefore, these distance values can advantageously dampen minor imbalances and vibrations.

In some embodiments according to the invention, the radial distance between the radial outer surface of the first stage and the radially opposite inner side of the bearing housing is between 0.13 mm and 0.2 mm, in particular between 0.14 mm and 0.18 mm. The radial distance can be 0.15 mm in particular. Since the distance is correlated to the volume of fluid in that gap and these values are larger than the second stage values, these distance values can advantageously dampen larger imbalances and vibrations.

In some embodiments according to the invention, the first step and/or the second step extends around the entire circumference of the bearing damping ring. As a result, high damping can advantageously be achieved.

By means of the bearing arrangement according to the invention, it is advantageously possible to damp particularly strong imbalances. Such strong imbalances can occur in the case of a so-called blade-off, a blade tearing off in the event of damage in a fan or also in a compressor and/or turbine stage of an aircraft engine. With such strong imbalances, the damping systems according to the prior art are no longer active. An example oil film for damping would tear off in this case and the vibrations, which often become resonance vibrations, can no longer be damped.

• 1 zeigt eine erfindungsgemäße Lageranordnung mit einem Kugellager in einer Längsschnittdarstellung;
• 2 zeigt einen Lagerdämpfungsring in einer Aufsicht von radial außen in einer ersten Ausführungsform mit Rillen auf der Oberfläche der zweiten Stufe; und
• 3 zeigt einen Lagerdämpfungsring in einer Aufsicht von radial außen in einer zweiten Ausführungsform mit Rillen auf der Oberfläche der ersten und der zweiten Stufe.

The present invention is explained below by way of example with reference to the attached drawings, in which identical reference symbols designate identical or similar components. In the greatly simplified figures, the following applies:

• 1 shows a bearing arrangement according to the invention with a ball bearing in a longitudinal section;
• 2 shows a bearing damping ring in a plan view from radially outside in a first embodiment with grooves on the surface of the second step; and
• 3 shows a bearing damping ring in a top view from radially outside in a second embodiment with grooves on the surface of the first and the second stage.

1 shows an exemplary bearing arrangement 100 according to the invention with a roller bearing designed as a ball bearing 1 in a longitudinal section. The ball bearing 1 comprises a bearing inner ring 3, a bearing outer ring 5 and balls 7 as rolling elements between the bearing inner ring 3 and the bearing outer ring 5.

The bearing inner ring 3 is connected radially on the inside to a shaft 9, for example by means of a non-positive press fit. The shaft 9 rotating in the operating state can be a gas turbine shaft for an aircraft engine.

The bearing arrangement according to the invention also includes a fluid 13 arranged between the outer bearing ring 5 and a bearing housing 11 arranged radially on the outside in an exemplary closed intermediate space. The axial boundaries of this space, such as piston rings, are in 1 not shown. The fluid 13 has the function of dampening, for example, vibrations and imbalances of the rotating shaft 9, as they usually occur in aircraft engines. The fluid 13 can be an oil, in particular a highly viscous oil. The bearing assembly 100 may function as hydraulic bearing dampening or as pinch oil dampening be designated. In English, the term "squeeze film damper" can be used. The bearing outer ring 5 is therefore designed as a bearing damping ring 5 .

According to the invention, the bearing damping ring 5 has a stepped outer profile. The first stage 15 has a smaller outer radius R1 compared to the second stage 17 with a larger outer radius R2 of the bearing damping ring 5. The first step 15 is arranged in the form of a groove between the two second steps 17 which are adjacent axially a. The axial extension 19 of the two adjacent second stages 17, which in 1 are not shown in full is greater than the axial extent 21 of the first stage 15.

The groove-like arrangement of the first stage 15 of the bearing damping ring 5 can be referred to as an elongated depression. In this embodiment, both the first stage 15 and the second stage 17 have, for example, a cylindrical shape.

With the bearing arrangement 100 according to the invention with the stepped shape of the bearing damping ring 5, it is advantageously possible to dampen particularly strong imbalances. In the case of small imbalances, the damping volume of the fluid 13 radially to the second stage 17 is often sufficient. In the case of large or severe imbalances, however, the gap between the radial outer surface of the second stage 17 and the radial inner side of the bearing housing 11 is minimized, so that the fluid 13 can no longer produce a damping effect in this intermediate space. However, the fluid 13 between the radial outer surface of the first stage 15 and the radial inner side of the bearing housing 11 is then still available for effective damping. A direct deformation of the bearing damping ring 5 in this area, ie radially to the balls 7 of the roller bearing 1, and thus to the fluid 13, can possibly also have a damping effect. Such strong imbalances can occur, for example, in the case of a so-called blade-off, ie a blade tearing off in a fan or also in a compressor and/or turbine stage of an aircraft engine.

2 shows a bearing damping ring 5 in a view from radially outside in a first embodiment with grooves 23 on the surface 25 of the second step 17 of the bearing damping ring 5.

The grooves 23 are straight and equidistant, purely by way of example. In other embodiments, the grooves 23 can have different widths in the circumferential direction u and other shapes. The grooves 23 can to 1 influence the dampening effect discussed directly and, if necessary, amplify it.

3 shows a bearing damping ring 5 in a top view from radially outside in a second embodiment with grooves 23, 27 on the surface of the first 15 and second 17 stage.

The grooves 27 of the first stage 15 are straight and equidistant, purely by way of example. In other embodiments, the grooves 27 can have different widths in the circumferential direction u and other shapes. Likewise, the grooves 23 of the second stage are wavy and equidistant, purely by way of example. In other embodiments, the grooves 27 can have different widths in the circumferential direction u and other shapes.

The grooves 23, 27 can to 1 influence the dampening effect discussed directly and, if necessary, amplify it.

Reference List

a

axial; axial direction; flow direction

and

circumferential direction; direction of rotation

right

radial; radial direction

R1

Outer radius of the first stage

R2

Second stage outer radius

100

bearing arrangement

1

Ball-bearing; roller bearing

3

bearing inner ring

5

bearing outer ring; bearing damping ring

7

ball of a ball bearing; rolling elements

9

wave

11

bearing housing

13

fluid; oil

15

first stage of the bearing damping ring

17

second stage of the bearing damping ring

19

second stage axial extension

21

axial extension of the first stage

23

Second stage grooves

25

Second level surface

27

First stage grooves

29

First level surface

Claims (9)

Bearing arrangement (100) for a rotating shaft (9), in particular for a gas turbine shaft, comprising a bearing inner ring (3), a bearing outer ring designed as a bearing damping ring (5), rolling bodies (7) which are located between the bearing inner ring (3) and the bearing damping ring (5 ) are arranged, a bearing housing (11) and a fluid (13) for bearing damping arranged between an outside of the bearing damping ring (5) and an outside of the radially opposite inside of the bearing housing (11), the bearing damping ring (5) for hydraulic bearing damping by means of the fluid (13), and wherein the bearing damping ring (5) has a stepped outer profile, with a first step (15) having a smaller outer radius (R1) compared to a second step (17) with a larger outer radius (R2) of the bearing damping ring (5 ), and wherein the first stage (15) is arranged in a groove between two axially (a) adjacent second stages (17), and the axial replacement elongation of the two adjacent second stages (17) corresponds at least to the axial extent of the first stage (15). Bearing arrangement (100) after claim 1 , wherein the first stage (15) is arranged radially (r) to the rolling elements (7). Bearing arrangement (100) after claim 1 or 2 , wherein the fluid (13) is an oil. Bearing arrangement (100) according to one of the preceding claims, wherein the groove shape of the first step (15) is rectangular or trapezoidal. Bearing arrangement (100) according to a Claims 1 until 3 , wherein the groove shape of the first stage (15) has a round, an oval or another cross-sectional shape. Bearing arrangement (100) according to one of the preceding claims, wherein the first stage (15) and/or the second stage (17) has grooves (23, 27) formed essentially in the axial direction (a). Bearing arrangement (100) according to one of the preceding claims, wherein the radial distance between the radial outer surface of the second step (17) and the radially opposite inner side of the bearing housing (11) is between 0.05 mm and 0.12 mm, in particular 0.1 mm amounts to. Bearing arrangement (100) according to one of the preceding claims, wherein the radial distance between the radial outer surface of the first stage (15) and the radially opposite inner side of the bearing housing (11) is between 0.13 mm and 0.2 mm, in particular between 0.14 mm and 0.18 mm, more particularly 0.15 mm. Bearing arrangement (100) according to any one of the preceding claims, wherein the first stage (15) and/or the second stage (17) extends around the entire circumference of the bearing damping ring (5).

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