WO2022237928A1

WO2022237928A1 - Bearing assembly, and method for operating a bearing assembly

Info

Publication number: WO2022237928A1
Application number: PCT/DE2022/100251
Authority: WO
Inventors: Johannes Bedenk
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2021-05-10
Filing date: 2022-04-01
Publication date: 2022-11-17
Also published as: DE102021112134B3

Abstract

A bearing assembly (1) comprises a rolling bearing (2) and a sliding bearing (3), wherein a race (7) of the rolling bearing (2) is at the same time a race (7) of the sliding bearing (3). The common race (7) of the rolling bearing (2) and the sliding bearing (3) has a lubricant circulation structure (15).

Description

1

Laqeranordnunq and procedures for operating a laqeranordnunq

The invention relates to a bearing arrangement which includes a roller bearing and a plain bearing. Furthermore, the invention relates to a method for operating such a bearing arrangement.

A bearing assembly with a combination of plain and roller bearings is known, for example, from DE 43 22 729 C1. The plain bearing of this bearing arrangement works with a definable or adjustable friction. For this purpose, a sliding ring of the sliding bearing can be clamped against a counter-sliding surface with an adjustable force. The roller bearing of the well-known roller-slide bearing combination is an axial ball bearing.

A further rolling plain bearing is disclosed in DE 1 525 146 A. This oil lubricated plain rolling bearing is designed for high speed, lightly loaded bearings and incorporates springs and friction discs to slow down bearing components. Tapered rollers are provided as rolling elements.

DE 12 86 344 A describes a radial roller bearing with two races which are rotatably mounted in a plain bearing, the plain bearings for the races each consisting of a support ring and a plain bearing bush arranged floating between the race and the support ring.

DE 26 28 828 A1 describes a bearing for shafts of turbochargers with a roller bearing, a lubricating oil supply and an axial plain bearing, which is arranged with a sliding ring on the fixed bearing flange and with a support ring rotating with the shaft to absorb axial forces of the shaft in one direction is, where at between the sliding ring and support ring a variable in the predetermined extent axial play is present.

In combination with bearings of other types, such as magnetic bearings, plain bearings are in principle suitable for taking on the function of a safety bearing in the event of a bearing failure, thus enabling emergency operation or the controlled shutdown of a machine. In this context reference is made to the documents DE 102013210 218 A1, WO 2012/025292 A1 and EP 2 522 870 A1 as examples. 2 sen. In the latter case, a sliding bearing is designed as an axial safety bearing, whereas a roller bearing is provided as a radial safety bearing.

The object of the invention is to provide a combination of roller and plain bearings that is more advanced than the prior art, has a compact structure and good emergency running properties.

This object is achieved according to the invention by a bearing arrangement having the features of claim 1. The object is also achieved by a method for operating a bearing arrangement according to claim. Configurations and advantages of the inventions explained below in connection with the operating method also apply to the device, ie the bearing arrangement, and vice versa.

The bearing assembly includes a roller bearing and a plain bearing, the plain bearing being designed as a bearing for emergency operation of the bearing assembly. A bearing ring of the roller bearing is also designed as a bearing ring of the plain bearing. This common bearing ring of the roller bearing and the plain bearing has a lubricant delivery structure which is designed to supply lubricant to the plain bearing, ie emergency bearing. In typical configurations, the roller bearing is located radially inside half of the plain bearing, which results in the structure of a three-ring bearing.

In normal operation, i.e. with proper functioning of the Wälzla gers, the common bearing ring rotates relative to another bearing ring of the roller bearing, whereas the common bearing ring and another bearing ring of the plain bearing typically represent components of a rigid arrangement of bearing components. In emergency operation, on the other hand, there is typically a rigid coupling of the components of the roller bearing, while the other bearing ring of the plain bearing rotates relative to the common bearing ring of the bearing assembly. 3

Due to the lubricant delivery structure of the common bearing ring, particularly good emergency running properties of the bearing arrangement are achieved in comparison to conventional solutions, with the lubricant delivery, which is caused by the common bearing ring, inevitably comes into operation in the event of a failure of the roller bearing.

The lubricant conveying structure can be formed on one face or on both faces of the common bearing ring. Individual conveying vanes of the lubricant conveying structure can extend outwards to the outer peripheral surface of the common bearing ring. Inwards, the impeller vanes end radially outside the inner peripheral surface of the common bearing ring. It has been shown that this minimizes lubricant losses towards the inside and at the same time an effective supply of lubricant to the sliding bearing, which is typically located radially outside of the roller bearing, can be ensured over a longer period of time.

The roller bearing, which is arranged radially inside the sliding bearing, is, for example, a double-row bearing, in particular a double-row angular contact ball bearing. The angular contact ball bearing can be designed as a bearing in an X arrangement or as a bearing in an O arrangement, in both cases, in addition to radial forces, there are also axial forces in both directions between the inner ring of the roller bearing and the outer ring of the roller bearing, which represents the common bearing ring. are transferrable. With regard to possible designs of double-row angular contact ball bearings, reference is made to the documents DE 102017 119 660 A1, DE 199 02 177 A1 and DE 102015 215 834 A1 by way of example.

Like the roller bearing, the plain bearing can be designed as a radial-axial bearing. Here, the sliding bearing can have a sliding surface on a cylindrical outer peripheral surface of the common bearing ring and two further sliding surfaces on the end faces of the common bearing ring. At the same time, the last-mentioned sliding surfaces can delimit contours of the lubricant conveying structure. 4

The sliding surface providing a radial bearing function does not necessarily extend over the entire width of the cylindrical outer peripheral surface of the common bearing ring of the roller and plain bearings. Rather, said sliding surface can be designed as a strip that is narrower in comparison to the width of the common bearing ring, which is touched on one side or on both sides by a lubricant chamber or two lubricant chambers.

The at least one lubricant chamber constantly supplies the plain bearing with lubricant in emergency operation. Lubricant that runs out of the lubricant chamber is permanently replaced by lubricant that flows in with the help of the lubricant conveying structure. Oil or grease can be used as a lubricant. Routine relubrication, which involves refilling the lubricant chamber described, can be carried out, for example, as part of maintenance work. Depending on the application, lifetime lubrication can also be considered.

The outer ring of the sliding bearing can be designed in one or more parts. In the case of a multi-part structure of the plain bearing outer ring, the individual bearing parts can have a uniform shape, be mirror images of one another, or be shaped differently from one another. Sliding surfaces, which are provided by the bearing parts of the plain bearing, can be coated in a manner known per se. This applies both to the sliding surfaces, which assume axial bearing functions, and to the at least one radial sliding bearing surface.

In a geometrically simple design, a plain bearing ring contacting the common bearing ring can be designed as an angle ring, that is to say it can be profiled in an L-shape. In this case, a radially inwardly directed section of the angle ring takes over an axial bearing function that is effective in exactly one direction, while a cylindrical section adjoining the radial bearing function, optionally together with another angle ring, takes over.

In a modified design, an angle ring can have a rim extending radially inwards from its cylindrical section and Contacted 5 cylindrical outer peripheral surface of the common bearing ring and thus serves the radial bearing. In cross section, the modified angle ring thus describes a U-profile with typically unequally long U-legs, the shorter U-leg, ie rim, forming the already mentioned sliding surface in the form of a narrow strip. The modified angle ring can be adjacent to another angle ring as a sliding bearing, which is either modified in a corresponding manner or designed as a simple L-shaped angle ring. In the latter case, the cylindrical portion of the angle ring can either rest completely on the outer peripheral surface of the common bearing ring or be completely lifted from this surface. If there is a distance between the outer peripheral surface of the common bearing ring and the inner peripheral surface of the cylindrical section of the win kelrings, this distance can be used to introduce and forward lubricant in the manner described in connection with the at least one lubricant chamber.

In various configurations of the bearing arrangement, there is at least one channel for supplying lubricant to the plain bearing. Such a channel, which increases the running time of the slide bearing through improved lubrication, can be formed in the common bearing ring, for example. In this case, lubricant can be promoted through the channel from the roller bearing to the plain bearing when the Wälzla ger no longer works and thus a relative rotation between the common seed bearing ring and the outer ring of the bearing assembly is set in motion.

Alternatively, at least one channel can be located in the outer ring of the bearing arrangement, in particular in an enlarged section of the outer ring that protrudes beyond the roller bearing in the axial direction, via which lubricant can be supplied to the plain bearing. A lubricant reservoir can be integrated in this channel. In particular, a lubricant reservoir, in which grease is kept ready as a lubricant for the sliding bearing, can be formed between the outer ring of the bearing arrangement and another element, which has the shape of an angle ring, for example.

The delivery of lubricant can be effected or supported by centrifugal forces which occur when the outer ring rotates. Around the lubricant reservoir 6 of the plain bearing, which is not active during normal operation, can be periodically filled with new lubricant, in particular grease, at least one grease nipple can be present at a suitable point in the bearing arrangement.

According to an advantageous development, the bearing arrangement includes a predetermined breaking element, which is designed to activate the plain bearing when the roller bearing is overloaded. By breaking the predetermined breaking element, the otherwise blocked plain bearing is released. The common bearing ring, the predetermined breaking element and the outer ring of the slide bearing thus interact in the manner of an overload clutch that can be triggered once.

In general, when the roller bearing is blocked, the plain bearing is put into operation and at the same time lubricant is conveyed from the roller bearing to the plain bearing through the common bearing ring of both bearings. The same applies if there is no blockage in the roller bearing, but a torque threshold value is exceeded, ie impermissible sluggishness occurs. The function of the entire bearing arrangement comprising the roller bearing and the plain bearing within a surrounding structure is in principle independent of whether the roller bearing or the plain bearing is in operation while the other bearing is inoperative.

The bearing arrangement is suitable, inter alia, for use in a blade adjustment of a tail rotor of a helicopter. For the technical background, reference is made in this context to the documents DE 1 118 017 A and EP 3 023 328 B1.

The tail rotor of a helicopter generates a torque about the vertical axis, i.e. the yaw axis. If the angle of attack of the tail rotor blades is adjusted, the moment generated by the tail rotor also changes. This adjustment can be effected by the pilot, in particular by means of pedals, the actuation of the pedals being converted into an adjustment of the angle of attack of the at least two blades of the tail rotor via a linear drive. A tail rotor of a lifting In principle, 7 screwdrivers can be driven in any way. An electric drive for a tail rotor is described, for example, in EP 2 412 630 B1.

Regardless of the application, during emergency operation of the bearing arrangement, which is equivalent to the fact that the plain bearing is in function, the plain bearing is permanently relubricated. This is particularly beneficial for the cooling of the bearing arrangement. Even in emergency operation, the bearing arrangement is characterized by high running accuracy.

Several exemplary embodiments of the invention are explained in more detail below with reference to a drawing. Show in it:

1 shows a bearing arrangement comprising a roller bearing and a plain bearing in a sectional view,

Fig. 2 Components of the bearing arrangement according to FIG. 1 in a simplified front-end view,

3 shows a detail of a bearing arrangement with a lubricant channel,

4 shows a further bearing arrangement with a lubricant channel in a representation analogous to FIG. 3.

Unless otherwise stated, the following explanations relate to all exemplary embodiments. Parts that correspond to one another or have basically the same effect are identified by the same reference symbols in all figures.

A bearing arrangement 1 is part of a blade adjustment, denoted overall by 10, of a tail rotor of a helicopter. The bearing assembly 1 includes a roller bearing 8th

2 and a plain bearing 3 and is therefore designed as a rolling plain bearing, with exactly one of the two bearings 2, 3 being in function in every operating state, as will be described in more detail below. The common central axis of the bearings 2, 3 is marked with MA be. ME designates a center plane of the bearing assembly 1.

The inner ring of the roller bearing 2 is denoted by 4 and in the present case zweitei lig, namely a first inner ring part 5 and a mirror image to this parent, identically shaped inner ring part 6 constructed. Overall, the roller bearing 2 is a double-row angular contact ball bearing in an O arrangement. On the inner ring parts 5, 6 roll balls as rolling elements 9, which leads ge in a cage 24 are.

The balls 9 contact at the same time a roller bearing outer ring 7, which represents a common bearing ring of the roller bearing 2 and the plain bearing 3. In addition to the common bearing ring 7, that is, the inner ring of the plain bearing 3, the plain bearing 3 has an outer ring 8, which is the outermost of the three bearing rings 4, 7, 8 that are concentric to one another. The rolling bearing 2 has an inner diameter d and an outer diameter D on.

In the intended operation of the blade adjustment 10, the outer ring 8 rotates together with the common bearing ring 7, whereas the inner ring 4 is a standing bearing ring. A blade of the tail rotor is adjusted by moving the inner ring 4 in the adjustment direction VR, ie along the center axis MA. In this case, the common bearing ring 7 and the outer ring 8 rotating with it are inevitably also displaced.

In the exemplary embodiment, the outer ring 8 is in two parts, namely a first plain bearing element 13 and a second plain bearing element 14 constructed. The Gleitla gerelemente 13, 14 each have a radially inwardly directed rim 17, 18, which connects to a cylindrical portion 19 of the outer ring 8, wherein the two rims 17, 18, the roller bearing 2 engage. 9

The end face of the common bearing ring 7 directly opposite the rims 17, 18 forms a lubricant conveying structure 15, which is illustrated in FIG. The lubricant conveying structure 15 includes conveying blades 16 which are formed by the common bearing ring 7 and have the task of conveying lubricant radially from the inside outwards and thus to the plain bearing 3 .

The slide bearing 3 has a lubricant chamber 20, which over most of the designated 12 outer peripheral surface of the common bearing ring 7 he stretches. The first plain bearing element 13 has a central rim 21 contacting the outer peripheral surface 12 , with which the plain bearing 3 can absorb radial forces acting between the outer ring 8 and the common bearing ring 7 . Axial forces are taken up by the shelves 17, 18. In the present case, in contrast to the plain bearing element 13, the plain bearing element 14 has no radial bearing function.

As can be seen from Figure 2, the conveyor blades 16 extend outwards to the outer peripheral surface 12 of the common bearing ring 7, but not inwards to the inner peripheral surface of the common bearing ring 7, which is designated 25. The conveyor blades 16 are formed, for example, by machining the end faces of the common bearing ring Bearing ring 7 produced.

As long as the common bearing ring 7 is freely rotatable relative to the inner ring 4, the plain bearing 3 remains inoperative. Any rotation of the outer ring 8 about the central axis MA is accompanied by a corresponding rotation of the common bearing ring 7 about the central axis MA. A pin 23 is firmly inserted into the common bearing ring 7 for this purpose. At the same time, the pin 23 engages in an opening 22 which is located in the outer ring 8 . In the circumferential direction of the outer ring 8, the pin 23 has no play or only a very small amount of play.

If too high moments between the inner ring 4 and the common bearing ring 7, which in extreme cases to a blockage between the inner ring 4 and the 10

Bearing ring 7, that is, a failure of the roller bearing 2, can be attributed, the pin 23 breaks, with which it represents a predetermined breaking element. At this moment, a rotation between the common bearing ring 7 and the outer ring 8 is released, which means that the bearing assembly 1 has to be converted from a pure rolling bearing to a plain bearing. The operability of the rotor blade adjustment 10 is retained in full in emergency operation, that is to say in plain bearing operation.

In the designs according to FIGS. 3 and 4, there are lubricant channels 26, 30 for supplying lubricant to the plain bearing 3 in emergency operation. In the case of FIG. 3, a lubricant channel 26 extends from the interior of the roller bearing 2 to the axial bearing surface of the plain bearing 3. During emergency operation of the bearing assembly 1, lubricant is conveyed radially from the inside to the outside through this lubricant channel 26.

In the embodiment according to FIG. 4, the outer ring 8 has an enlarged section

27, which can be used to supply the plain bearing 3 in emergency operation. In the lubricant channel 30, a lubricant chamber 29 is integrated in this case, wel che by the outer ring 8 and another element, which is here as an angle ring

28 is formed, is limited. The lubricant channel 30 continues from the lubricant chamber 29 to the axial bearing surface of the slide bearing 3 . The lubricant chamber 29 can be filled with new grease via the section of the lubricant channel 30 extending in the radial direction and a lubricating nipple (not shown). Alternatively, the plain bearing 3 can be filled with lubricant for life.

11

Bearing arrangement bearing plain bearing inner ring inner ring part inner ring part common bearing ring of the rolling bearing and the plain bearing outer ring rolling element, ball rotor blade adjustment seal outer peripheral surface of the common bearing ring first plain bearing element second plain bearing element lubricant conveying structure conveyor blade board board cylindrical section of the outer ring lubricant space center board opening predetermined breaking element, pin cage inner peripheral surface channel in the common bearing ring extension section of the Outer ring Angle ring Lubrication chamber Channel in the outer ring 12 d inner diameter of the rolling bearing D outer diameter of the rolling bearing MA central axis ME central plane

Claims

13 patent claims

1 . Bearing arrangement (1), comprising a roller bearing (2) and a plain bearing

(3), wherein a bearing ring (7) of the roller bearing (2) is also designed as a bearing ring (7) of the plain bearing (3), characterized in that the common La gerring (7) of the roller bearing (2) and the plain bearing ( 3) has a lubricant conveying structure (15) which is formed on at least one end face of the common bearing ring (7) and comprises conveying blades (16) which end radially inwards outside the inner diameter of the common bearing ring (7).

2. Bearing arrangement (1) according to claim 13, characterized in that the roller bearing (2) is designed as a double-row ball bearing.

3. Bearing arrangement (1) according to claim 1 or 2, characterized in that a lubricant supply of the plain bearing (3) provided channel (26, 30).

4. Bearing arrangement (1) according to any one of claims 1 to 3, characterized in that the sliding bearing (3) is designed as a radial-axial bearing.

5. Bearing arrangement (1) according to claim 4, characterized in that the sliding bearing (3) has a sliding surface on a cylindrical outer peripheral surface (12) of the common bearing ring (7) and two further sliding surfaces on the end faces of the common bearing ring (7).

6. Bearing arrangement (1) according to any one of claims 1 to 5, characterized by a predetermined breaking element (23) which is designed to put the slide bearing (3) in an overload of the roller bearing (2) in function. 14

7. Bearing arrangement (1) according to claim 6, characterized in that the predetermined breaking element (23) is designed as a pin which passes through an opening (22) in an outer ring (8) of the plain bearing (3) into the common bearing ring (7 ) is used.

8. A method for operating a bearing arrangement (1), which comprises a roller bearing (2) and a plain bearing (3), wherein a bearing ring (7) of the roller bearing (2) is formed at the same time as a bearing ring (7) of the plain bearing (3). , wherein the common bearing ring (7) of the roller bearing (2) and the plain bearing (3) has a lubricant conveying structure (15) which is formed on at least one end face of the common bearing ring (7) and comprises conveying blades (16) which radially inside, outside the inside diameter of the common bearing ring (7), whereby if the roller bearing (2) is blocked, the slide bearing (3) is put into operation and at the same time lubricant is released from the roller bearing through the common bearing ring (7) of both bearings (2, 3). (2) is conveyed to the slide bearing (3).