DE102022207396A1 - Axial plain bearings with deformable support elements - Google Patents

Abstract

The invention relates to an axial plain bearing (01) for axially supporting a rotor of a gas turbine. This has a bearing housing (02) and a plurality of sliding bodies (03) and a plurality of support elements (07). The sliding bodies (03) are supported axially on support elements (07) and these in turn are supported on the bearing housing (02). To balance the axial forces on the individual sliding bodies (03), the support elements (07) have an elastically deformable deformation section (08). In order to achieve the most even distribution of force possible, it is provided that the support elements (07) also deform plastically in the event of an overload.

Description

The invention relates to an axial plain bearing with deformable support elements, which enable compensation to achieve a uniform surface pressure.

Various designs of axial plain bearings, which are used in particular with high axial forces, are known from the prior art. For example, such axial plain bearings are used in gas turbines to support the turbine rotor. The axial plain bearings have a plurality of sliding bodies distributed around the circumference, over which the axial force is transmitted from the rotor to the bearing housing.

In order to achieve an even load distribution on the individual sliding bodies, it is necessary to provide a compensation option between the individual sliding bodies. There are basically two different construction methods that can be considered. In a first, comparatively complicated arrangement, the individual sliding bodies are each mounted on tilting segments connected to one another. In this way, an even load on all sliding bodies can be achieved in an almost ideal manner. However, the disadvantage is the complicated structure and the associated high costs of a corresponding system.

A significantly simpler design is achieved if the individual sliding bodies are mounted elastically. For this purpose, there is an elastically deformable support body under each sliding body, so that with different loads on the sliding bodies, a different flexibility of the support bodies in return leads to a compensation of the axial load transmitted. Although this does not achieve a homogeneous distribution of the axial load, the differences can be reduced to small values at significantly lower costs for a corresponding bearing system.

In order to prevent an overload of the support body without over-dimensioning it, it is generally provided that the deformation of the support body is limited in such a way that from an expected maximum axial load of the support body on the bearing body blocks and no further deformation is possible.

Exemplary embodiments for such axial plain bearings are from the publications US 1684693 and the DE 4343965 known.

The disadvantage of this system, however, turns out to be that with a repeated, similar load distribution between the individual sliding bodies of the axial plain bearing, a repeated constant deformation of the support bodies with constant differences (remaining after the deformation) between the surface pressures on the individual sliding bodies remains.

The object of the present invention is therefore to achieve a better distribution of the axial load on the sliding bodies without the need for movable tilting segments.

The task is solved by an axial plain bearing according to the embodiment according to the teaching of claim 1.

Advantageous embodiments are the subject of the subclaims.

The generic axial plain bearing serves to support a rotor. What type of rotor this is is initially irrelevant. However, the embodiment is particularly suitable for supporting larger axial loads and the requirement for an even distribution of the axial load on the individual sliding bodies. Accordingly, the use of axial plain bearings in gas turbines is advantageous.

The axial plain bearing initially has a bearing housing and a plurality of sliding bodies distributed around the circumference. The sliding bodies each have a sliding surface that extends in the radial direction and in the circumferential direction on the side facing away from the bearing housing. On the axially opposite side there is a support section on which the respective sliding body rests and through which the axial forces are transmitted.

Furthermore, a plurality of supporting elements are present, via which the bearing forces are transmitted from the sliding bodies to the bearing housing. Accordingly, the respective sliding bodies with the respective support section rest against a support element in the axial direction. In relation to the support section in the circumferential direction and/or in the radial direction, the support element is again supported on the bearing housing in the axial direction. Furthermore, it is necessary that the support element each has a deformation section, which can deform when the support element is subjected to axial loading. Accordingly, it is necessary that the support element is positioned at the position of the support section of the bearing housing in the axial direction.

Expressly included in the generic or inventive embodiment of the axial plain bearing is an embodiment in which the support elements are located in the axial direction on a (one-piece or multi-part) in the axial direction Support adjustable bearing body, the axially adjustable bearing body in turn being mounted in the bearing housing and, for example, hydraulically adjustable in the axial direction. An essential aspect for the generic embodiment is that it is possible to compensate for the axial load on the individual sliding bodies when they are in different axial positions (which may be necessary even with minimal axial offset), with at least two support bodies, in particular all of them, on one each support a common bearing element (and therefore require axial compensation).

Expected axial loads occur when the axial plain bearing is used as intended. A nominal load is assumed to be the maximum axial load that occurs during regular operating behavior. Accordingly, the axial plain bearing must be designed taking the nominal load into account. It should be noted that in conjunction with the axial plain bearing, the nominal load is the total axial load to be transmitted by the rotor via the axial plain bearing. In contrast, the nominal load in relation to a sliding body or a support element is the load that results from dividing the nominal load acting on the axial plain bearing by the number of sliding bodies or support elements.

The support elements must be designed in such a way that the deformation section is deformed essentially elastically at the nominal load. Hysteresis due to recurring loading or permanent minimal deformation, which is common in many types of steel, is neglected here.

An improvement in terms of balancing the individual axial loads on the individual sliding bodies by means of flexibility of the support elements is achieved according to the invention in that the support elements are designed in such a way that plastic deformation occurs when a load exceeds the nominal load. Here it is required that the plastic deformation occurs at least at 1.5 times the nominal load.

Although it initially seems contradictory to provide for a plastic deformation of the support elements in the design, the plastic deformation enables a more even distribution of the axial load to the individual sliding bodies. It is generally assumed that the axial load on the individual sliding bodies is not static, but rather dynamically changing. If, for example, a sliding body is now minimally offset in the axial direction, the load in excess of the nominal load leads to plastic deformation of the associated support element. This in turn leads to a lower axial load on this sliding body when loaded again, since due to the plastic deformation of the support element, the sliding body is already offset in the axial direction compared to the starting position without any load.

What can be seen as a disadvantage of this design is that when the sliding bodies are replaced and thus a possible change in the axial position of the sliding surface and, as a result, a change in the distribution of the load on the axial plain bearing on the individual sliding bodies, this again leads to different loads on the individual sliding bodies . Accordingly, when replacing the sliding bodies, it can be advantageous to also replace the support elements, which may possibly be plastically deformed. However, the advantage of a better distribution of the axial load on the sliding bodies outweighs the disadvantage of possibly having to replace the support elements when replacing the sliding bodies.

First of all, it can be provided that a plastic deformation of the support element takes place at the support point of the support section and that this is pressed into, for example, a soft material. However, since plastic deformation should essentially be prevented up to the nominal load, attention must be paid to the precise design of the material and geometry.

In contrast, it is particularly advantageous if the deformation section deforms not only elastically but also plastically when subjected to a load in excess of the nominal load, in particular from 1.5 times the nominal load.

Furthermore, it is advantageous to design support elements in such a way that the plastic deformation occurs at 1.2 times the nominal load. It is particularly advantageous if the deformation section is plastically deformed from 1.2 times the nominal load.

It is advantageously provided that the support element allows deformation at least up to 1.5 times the nominal load. In this respect, it is necessary in this case that even with 1.5 times the nominal load on the support element, it is still in contact with the bearing housing on the side opposite to the support section in the axial direction.

It is particularly advantageously provided that at least at 1.8 times the nominal load there is an undiminished, albeit minimal, distance between the support elements and the bearing housing at the position opposite the support section.

The basic idea of the invention is that when a sliding body is loaded beyond the nominal load, a plastic deformation of the support element occurs and as a result, after relief and renewed loading due to the axial displacement caused by the plastic deformation, the load on this sliding body is lower than before the plastic deformation Deformation.

For this purpose, the support element is advantageously designed in such a way that after the axial plain bearing is loaded for the first time with 1.5 times the nominal load and a subsequent relief of the load, the plastic deformation on individual support elements leads to a new distribution of the load on the individual sliding bodies of the axial plain bearing. When the axial plain bearing is loaded again with the nominal load, none of the individual support elements distributed around the circumference should have a load higher than 1.2 times the nominal load.

Particularly preferably, the support elements are designed in such a way that after the axial plain bearing has been loaded with 1.5 times the nominal load and subsequent relief when loaded again up to the nominal load, no higher than 1.1 times the nominal load occurs on any of the individual support elements.

If all components are in the ideal position during assembly and there are no tolerances, each of the individual support elements is obviously subject to identical loads. However, if - as is usually to be expected - tolerances and deformations lead to uneven loading, the axial plain bearing according to the invention also ensures its function in this case with a reasonably uniform load on all individual sliding bodies.

Taking into account the frictional forces on the sliding bodies that occur during the rotation of the rotor to be supported in conjunction with the axial load present, there is generally a small offset from the geometric center of the sliding body with respect to the forces to be transmitted to the associated support elements. Accordingly, it can be advantageous to arrange the support section off-center on the sliding body in the circumferential direction.

The support elements required for each sliding body can be implemented in different ways. In a simple embodiment, it can be provided that an associated separate support element is provided for each sliding body.

In contrast, it can also be provided that an annular compensating disk is used, the sections of which are distributed around the circumference and form the respective support elements. If no division into an upper half and a lower half is required for assembly, for example, this is the preferred embodiment.

If it is necessary to divide the axial plain bearing into an upper half and a lower half, the support elements are preferably implemented by an upper half ring and a lower half ring.

Regardless of this, however, it is also possible to implement two or more support elements using a single component, several of which are arranged around the circumference.

Although a fixed position of the support elements is essentially given when using the axial plain bearing and a load on the sliding bodies, it is still advantageous if the support elements are mounted in a fixed manner on the bearing housing at least in the radial direction and in the circumferential direction.

The support elements can be stored differently depending on the embodiment, and these can be fixed to the bearing housing using screws, for example. If an annular compensating disk or two half rings are present, circumferential securing by means of axially engaging webs or pins may be sufficient, with the radial position resulting from the annular shape, or realized by a corresponding annular receptacle for the compensating disk or the half rings in the bearing housing can be.

• 1 eine Ansicht auf das beispielhafte Axialgleitlager in Achsrichtung;
• 2 ein Querschnitt durch das beispielhafte Axialgleitlager;
• 3 ein Schnitt durch ein Stützelement;
• 4 schematisch die Verformung des Stützelemente bei verschiedenen Lastzuständen.

An exemplary embodiment for an axial plain bearing is sketched in the following figures. Show it:

• 1 a view of the exemplary axial plain bearing in the axial direction;
• 2 a cross section through the exemplary axial plain bearing;
• 3 a section through a support element;
• 4 schematically shows the deformation of the support elements under different load conditions.

The 1 shows an exemplary embodiment for an axial plain bearing 01 in a view of the sliding bodies 03 in the axial direction of the axial plain bearing 01. You can see the surrounding bearing housing 02 and the bearing bodies 03, which are distributed around the circumference, with the respective sliding surface 04. For better visibility, the illustration of three sliding bodies 03 dispensed with. As a result, the compensating disk 06 located under the sliding body 03 is visible in sections. From The equal washer 06 forms the individual support elements 07 with sections distributed around the circumference. The support elements 07 in turn each have a deformation section 08, in the middle area of which there is a support surface 09. Also visible in this exemplary embodiment is a fixing element 13 with which the compensating disk 06 is fastened to the bearing housing 02.

In the 2 The axial plain bearing 01 is made from the 1 sketched in cross section. First of all, you can see the simply shown bearing housing 02 and the sliding bodies 03, which are distributed around the circumference. These 03 each have the sliding surface 04 on the side facing away from the bearing housing 02. Opposite the sliding surface 04 there are the support sections 05, via which the axial load is transmitted by the sliding bodies 03.

The support elements 07 are arranged between the bearing housing 02 and the sliding bodies 03, which 07 are jointly formed by a compensating disk 06. A section of the compensating disk 06, i.e. one of the support elements 07, is in the 3 shown in cross section. The deformation section 08 present over most of the extension can be seen. In this area, the support element 07 is opposed to the bearing housing 02. The support on the bearing housing 02 takes place via the support surfaces 11 of the support sections 10 on both sides in the circumferential direction. Axially opposite in the middle area is the support surface 09, on which the respective support section 05 of the respective sliding body 03 comes into contact.

Also visible is the circumferential securing 12 selected in this case to prevent the support elements 07 from shifting in the circumferential direction.

In the 4 Different load conditions for the support element 07 will now be outlined as examples.

First of all, the initial state is shown in which there is a distance 15a without load between the support element 07 and the bearing housing 02, axially opposite the support surface 09.

If the support element is now loaded axially with the nominal load, the distance 15b at nominal load is reduced.

If there is a further load up to 1.5 times the nominal load, the distance 15c is obviously reduced further, although there is still a small amount of free space to the bearing housing.

If the support element 07 is now relieved of the load, the distance 15d increases after the overload. The dashed line should represent the initial state. Accordingly, it can be seen that there is a plastic deformation and the support element 07 no longer returns to the starting position.

If the support element 07 is now loaded again with the nominal load, the distance 15e between the support element 07 and the bearing housing 02 opposite the support surface 09 is smaller than in the first case of the distance 15b.

This representation shows that the plastic deformation leads to an axial displacement of the adjacent sliding body 03 without axial loading. As a result, this leads to a lower load on this sliding body 03 in relation to the sliding bodies 03 present on the circumference. A better distribution of the axial load acting on the axial plain bearing can thus be achieved.

However, if an individual sliding body 03 is not loaded beyond the nominal load during operation and therefore no plastic deformation occurs, then there is no permanent overloading of the sliding body 03. Those sliding bodies 03, which are overloaded beyond the nominal load, are subsequently relieved again by the plastic deformation.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 1684693 [0006]
• DE 4343965 [0006]

Claims (9)

Axial plain bearing (01) for axially supporting a rotor, in particular a gas turbine, - with a bearing housing (02); and - with a plurality of sliding bodies (03) arranged distributed around the circumference, each of which (03) has a sliding surface (04) pointing away from the bearing housing (02) and extending radially and in the circumferential direction and a support section (05) facing axially opposite the bearing housing (02). exhibit; and - with a plurality of support elements (07), which (07) each have a deformation section (08) and on which (07) a support section (05) rests and the (07) are supported in the axial direction on the bearing housing (02) and are spaced apart from the bearing housing (02) in the axial direction opposite the support section (05); wherein when a respective support element (07) is loaded with a nominal load, its deformation section (08) is deformed substantially elastically, characterized in that when a respective support element (07) is loaded with 1.5 times the nominal load, this (07) is plastic is deformed. Axial plain bearing (01). Claim 1 , wherein when a respective support element (07) is loaded with 1.5 times the nominal load, the deformation section (08) is plastically deformed. Axial plain bearing (01). Claim 1 or 2 , whereby when a respective support element (07) is loaded with 1.2 times the nominal load, this (07) is plastically deformed; and/or wherein when a respective support element (07) is loaded with 1.2 times the nominal load, the deformation section (08) is plastically deformed. Axial plain bearing (01) according to one of the Claims 1 until 3 , wherein the respective support element (07) is spaced in the axial direction from the bearing housing (02) opposite the support section (05) when subjected to a load of 1.5 times the nominal load; and/or wherein the respective support element (07) is spaced apart from the bearing housing (02) in the axial direction opposite the support section (05) when subjected to a load of 1.8 times the nominal load. Axial plain bearing (01) according to one of the Claims 1 until 4 , whereby after an initial loading of the axial plain bearing (01) with 1.5 times the nominal load and a subsequent relief and a new loading of the axial plain bearing (01) with 1.0 times the nominal load on none of the support elements (07) is a higher than 1.2 times the nominal load occurs. Axial plain bearing (01) according to one of the Claims 1 until 5 , wherein the support section (05) is arranged off-center on the sliding body (03) in the circumferential direction. Axial plain bearing (01) according to one of the Claims 1 until 6 , wherein the support elements (07) are mounted individually on the bearing housing (02). Axial plain bearing (01) according to one of the Claims 1 until 6 , whereby all support elements (07) are part of an annular compensating disk (06); or wherein the support elements (07) are part of an upper half ring or a lower half ring. Axial plain bearing (01) according to one of the Claims 1 until 8th , wherein the support elements (07) are fixedly mounted on the bearing housing (02) in the radial direction and in the circumferential direction.

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