EP3027919A1

EP3027919A1 - Rolling-element bearing for a gearing

Info

Publication number: EP3027919A1
Application number: EP14739084.3A
Authority: EP
Inventors: Dirk Leimann; Kurt Engelen
Original assignee: ZF Wind Power Antwerpen NV; ZF Friedrichshafen AG
Current assignee: ZF Wind Power Antwerpen NV; ZF Friedrichshafen AG
Priority date: 2013-07-29
Filing date: 2014-06-30
Publication date: 2016-06-08
Also published as: US20160169288A1; CN105452693A; WO2015014554A1; JP2016531250A; DE102013214703A1

Abstract

The invention relates to a rolling-element bearing for a gearing, wherein the rolling-element bearing comprises an inner bearing ring (13), an outer bearing ring (14), and at least one rolling element (15), wherein the rolling-element bearing has a sensor (19), which is rigidly arranged in relation to a gearing part or a part of the rolling-element bearing, and the rolling element comprises a depth deviation (16) on at least one lateral surface (17), wherein the depth deviation is designed in such a way that the lateral surface of the rolling element has at least two different depths along a circular path about an axis of rotation of the rolling element and the sensor is positioned in order to detect the depth deviation.

Description

Rolling bearings for a transmission

Technical field of the invention

The present invention relates to a rolling bearing for a transmission according to the preamble of independent claim 1 and to a method for determining the speed, the rotational speed and / or the slip of at least one rolling body according to the preamble of independent claim 10.

General state of the art

Rolling bearings are used in particular to rotatably support shafts and often have an inner ring, an outer ring and a rolling element. In this case, the inner ring is disposed within the outer ring and the rolling elements between the inner ring and the outer ring. The rolling elements roll on the inner ring and the outer ring.

Since bearings, such as rolling bearings, are important components of transmissions, for example of transmissions for a wind turbine, and bearing damage can lead to a total failure of the transmission, it is necessary to be able to analyze bearing damage accurately. An important part of the analysis of bearing damage is the slip measurement to determine slippage in the bearing. As a slip is hereinafter referred to a sliding movement of the rolling elements relative to the inner and / or outer ring of the bearing. In general, three types of slip are important here, namely cage slip, roller slip, and axial slip.

FIG. 1 shows the three types of slip. FIG. 1 shows a bearing 1 with an inner ring 2, an outer ring 3 and rolling elements 4 between the inner ring 2 and the outer ring 3.

Sliding motion of a rolling element 4 in the circumferential direction of the inner or outer ring is referred to as rolling element slip 5.

Such a sliding movement of the rolling element 4 may be combined with sliding movements in other directions or rotational movements. Axial slip 6 is understood as meaning a movement of a rolling element 4, in which the rolling element 4 moves along its axis of rotation.

Cage slip 7 is understood as a sliding of the inner ring and / or the outer ring on the rolling elements.

Methods for determining the Wälzkörperschlups are already known.

DE 102008 061 280 shows a method for detecting the rotational speed of a rolling element by means of measuring the magnetic field of one or more magnetized rolling elements. Also, optical methods, such as the use of a high-speed camera, are usually used in conjunction with an image derotation prism for detecting the rotational speed of the rolling element.

However, the above-described methods may be limited or not suitable for use in wind turbines. When using optical methods, existing lubricating oils or greases needed to lubricate rotating parts can affect the visibility of the rolling elements. In addition, the realization of a camera in a wind turbine gear is often disadvantageous, even because of the space required.

When using magnetized rolling elements there is a risk that they are attracted by these metal particles and this leads to premature bearing damage. Furthermore, the results obtained by magnetic methods are often unreliable because wind power transmissions are partially made of magnetic materials that affect the magnetic field measurements. In addition, the measurements are often disturbed by existing in wind power transmissions electrical Irrströmen. Object of the invention

It is an object of the invention to provide an apparatus and / or a method which is suitable for determining the slip of at least one part of a roller bearing.

This object is achieved by a rolling bearing according to claim 1 and a method according to claim 10. Preferred embodiments can be found in the subclaims.

Summary of the invention

In particular, the object can be achieved by a rolling bearing for a transmission, in particular a transmission for a wind turbine. The rolling bearing may include a bearing inner ring, a bearing outer ring and at least one rolling element.

The rolling bearing has a fixed relative to a transmission parts or a part of the rolling bearing sensor. The rolling element has a depth deviation at least on one side surface. The depth deviation is designed so that the side surface of the rolling body along a circular path about an axis of rotation of the rolling body has at least two different depths. The sensor is positioned so that it can detect the depth deviation.

It has therefore been recognized that a speed, position, or slip measurement can be made by means of the depth deviations on the rolling elements and a sensor which detects these depth deviations. This measurement can dispense with the use of sensitive optical methods or a magnetic field and thus provide a reliable measurement.

The inner ring or the outer ring need not be designed as a separate component, but also bearing inner rings or bearing outer rings are known, which are integrated in another component or part of the component. Thus, the in- nenring be designed as part of a rotatably supported by the bearing shaft to be stored. Also, the bearing outer ring may be a housing part or a part of a gear, such as a planet.

The sensor may be fixed with respect to a gear part and / or fixed with respect to a bearing part. This facilitates the calculation of the slip from the signals of the sensor, in particular when the relative movement of the gear part or the bearing part relative to the bearing inner ring and / or the bearing outer ring is known. In addition, in an arrangement of the sensor fixed relative to a gear and / or bearing component, the transmission or the bearing can be manufactured and mounted as a closed component.

In particular, the sensor can be mounted so that it detects the depth deviation as a function of the position of the axis of rotation of the rolling body and in dependence on the angular position of the rolling body.

Thus, a sensor can be arranged so that it detects the depth deviation only when it is at a certain position. Thus, the slip of the rolling body can be detected via a recurrent detection of the depth deviation on the rotating rolling body. Also, the sensor or a plurality of sensors may be arranged so that the depth deviations are detected at different positions. This makes it possible to track the trajectory of the depth deviation at least in sections, and thus to detect the speed, the position, the acceleration and / or the slippage of the rolling body.

A depth deviation is understood below to mean the deviation of the surface of the rolling element to a plane perpendicular to the axis of rotation of the rolling element, the plane including at least one point on the surface of the rolling element. If the rolling element has a depth deviation, this means that not the entire side surface of the rolling element lies on a plane perpendicular to the axis of rotation of the rolling element. As a side surface of the rolling body, in particular a side is understood, which does not run on the inner ring and / or the outer ring. It can also be understood as one or more sides of the rolling element, which is perpendicular to the running surface of the rolling body. Under the tread is the surface of the rolling element understood, over which the rolling body rolls at least mainly on the inner or outer ring. The arrangement of the depth deviation on the side surface of the rolling element prevents the depth deviation from coming into contact with the running surface of the inner and / or outer ring and thus changing the running properties of the rolling element. Also, it is possible by the arrangement of the depth deviation on the side surface of the rolling body to position the corresponding sensor only laterally, so that detection of the depth deviation can be avoided by the inner and / or outer ring.

Preferably, at least one rolling element, in particular a plurality of rolling elements, particularly preferably all rolling elements of the rolling bearing, have depth deviations. For example, the slippage of several rolling elements can be analyzed, making the investigation methods more accurate and comprehensive.

Preferably, the at least one rolling element on several depth deviations. Preferably, the depth deviations are arranged at a uniform distance from each other on a circle about the axis of rotation of the rolling body. But it also rolling elements are possible in which the depth deviations are arranged at different intervals. Thus, the orientation of the rolling element can be coded via the distance between the depth deviations.

In a preferred embodiment, the depth deviations are positioned at all rolling elements with such depth deviations in the same places. The rolling elements with depth deviations thus do not differ from each other by the position of this depth deviation. Thus, the signal detected by the sensor is independent of the rolling element. This facilitates the evaluation of the sensor signals and thus the analysis of the slip. However, it is also possible that different rolling elements have different depth deviations. Thus, the position of the depth deviations or the height difference between the side surface and the depth deviation between the variations in depth of a rolling element or between the variations in depth of different rolling elements can vary and so the position of the rolling elements or the rolling elements are coded on the depth deviations.

Also, the shape of the depth deviation, e.g. the cross section of the depth deviation vary.

At least one of the depth deviations can be formed by a recess. Such a recess may have a circular cross-section. However, other shapes, such as triangular, quadrangular, polygonal, star-shaped or irregular cross-sections of the recesses are possible. Preferably, a plurality of the depth deviations, in particular all deviations in depth, are formed on a rolling body as a recess. In particular, all variations in depth of the rolling elements can be designed as recesses.

Recesses can be easily attached to side surfaces of rolling elements, for example by drilling, milling, etching and the like. Also, the rolling element can be manufactured in the intended shape, as cast, without the recess being added in a post-processing. Also, rolling elements can be guided in the part of the side surface, which has the recesses, by an inner ring and / or an outer ring without the recess scratching or destroying the inner ring and / or outer ring.

At least one, in particular several or even all deviations in depth can be formed by a material surplus. Such excess material can be added to the rolling element by soldering and / or welding. Also, the surplus material can already be formed on the side surface of the rolling element during the production of the rolling element. The formation of the depth deviation in the form of an excess of material allows the depth deviation at the Side surface of the rolling element, without the rolling element is weakened by a material removal

The sensor may be attached to the inner ring of the rolling bearing, to the outer ring of the rolling bearing, to a cage of the rolling bearing, to a housing of the transmission or to a shaft of the transmission.

By attaching the sensor to the inner and / or outer ring of the sensor can be arranged in a simple manner fixed relative to the inner and / or outer ring. Also, so the slip of the rolling elements can be detected for several rolling elements, if several rolling elements have one or more suitable depth deviations, since the rolling elements move relative to the inner and / or outer ring usually and so several rolling elements offset by a fixed time the sensor attached to the inner and / or outer ring can be detected.

By attaching the sensor to the rolling cage in particular the slip of a rolling element can be detected, since the axis of rotation of the rolling elements is fixed to the cage. Thus, the slip of a single rolling element can be detected without having to take into account a relative movement of the axis of rotation to the sensor. This further facilitates the calculation of the Wälzkörperschlupfes.

Also, the sensor can be attached to the transmission housing or a transmission shaft. Since the gear housing is fixed, it is particularly suitable for attachment of components, since no dynamic properties of the housing must be considered for the attachment. The arrangement of the sensor on a shaft may be advantageous since such waves are positioned at least close to the bearing and thus to the rolling elements and in particular in wind power transmissions have masses which are large in relation to the sensor mass, so that the attachment of the sensor to a shaft represents no or only a slight influence on the dynamic properties of the shaft.

In particular, the sensor can be a distance sensor, in particular an eddy current sensor, an inductive proximity sensor, a Hall sensor or a dental be wheel sensor. Such sensors are suitable for detecting the deviations in depth that are arranged on a surface of a rolling body which is located in the detection range of the sensor. The measurement of the speed and the orientation of the rolling body on the basis of a depth deviation signal makes it possible to dispense with sensitive and / or disturbing measurements.

Preferably, the one rolling element or a plurality of rolling elements or all rolling elements is spherical, conical or pendulum roller body or toroidal rolling elements. Such rolling elements are particularly suitable to be used in a transmission for a wind turbine position.

The rolling element preferably has at least one running surface and at least one side surface with at least one depth deviation, so that the rolling element has at least two different depths along a circular line about the axis of rotation of the rolling element.

The object can also be achieved by a method for determining the speed, the rotational speed and / or the slip of at least one rolling element of a roller bearing, wherein at least one rolling element has different depths on a circular path about the axis of rotation and a sensor is arranged on a part of the roller bearing in that the depth deviation can be detected, the speed, the rotational speed and / or the slip being calculated from the sensor signal, in particular the time interval of the sensor signals, which are dependent on a passage of the depth deviation at the sensor.

Furthermore, the invention will be explained in more detail using an exemplary embodiment with the aid of the drawings. It shows

1 different types of slip,

2 a rolling bearing arrangement,

3 shows a part of a rolling bearing,

4 different depth deviations, 5 different depth deviations, which are mounted on a side surface of the rolling elements of a bearing,

6 shows the position of the sensor,

7 to 10 parts of a rolling bearing and the position of the sensor,

Fig. 1 1 (a) the computational path of a mounted on the outer ring of the bearing

Sensors for different degrees of hatching,

Fig. 1 1 (b) the resulting sensor signal over time

FIG. 11 (c) shows the time between different pulses with estimated parabolas. FIG.

12 Monte Carlo simulation for a rolling element with 20 depth deviations and different degrees of slip,

13 Monte Carlo simulation for a rolling element with 20 depth deviations, FIG. 14 test results for a rolling element with a diameter of 58 mm and 20 depth deviations, FIG.

Fig. 15 test results for a rolling element with a diameter of 58 mm and 20 depth deviations and different Schlupfarten.

Description of exemplary embodiments

The term "includes" is not to be construed as limiting the invention in any way The term "comprising" as used in the claims should not be limited to the nature of the agent described hereafter; he does not exclude other elements, parts or steps.

As used in the claims and the description, the term "connected / connected" is not to be construed as limiting to direct connections unless otherwise indicated, so the statement that part A is connected to part B is not It also encompasses indirect contact between Part A and Part B, in other words, it also includes the case where there are intermediate parts between Part A and Part B. Not all embodiments of the invention embrace all features of the invention. In the following description and in the claims, any of the claimed embodiments may be used in any combination.

Figure 2 illustrates schematically a shaft-bearing assembly 10. The shaft bearing assembly 10 includes a shaft 1 1, which is supported by at least one bearing 12. The shaft 1 1 can e.g. be a planetary shaft, a transmission shaft, a pinion shaft or a hollow shaft. In particular, the shaft 1 1 may be a shaft in a wind power transmission. The bearing 12, a detail of which is shown in Fig. 3, comprises an inner ring 13, an outer ring 14 and rolling elements 15 between the inner ring 13 and the outer ring 14. In particular, the outer ring 14 of the bearing 12 may be incorporated into a part of the transmission, e.g. be integrated in a planetary gear of the transmission. The bearing 12 may be a roller bearing with cylindrical rolling elements 15, conical rolling elements 15, spherical roller bodies 15 or toroidal rolling elements 15. The bearing 12 may be a radial bearing or a thrust bearing.

In one embodiment, at least one of the rolling elements 15 of the bearing 12 has at least one depth deviation 1 6. In the example mentioned, one of the rolling elements 15 comprises a plurality of depth deviations 16, which are circumferentially spaced from one another on the rolling element 15. The rolling elements 15 have two side surfaces 17 and a rolling surface 18, wherein the depth deviations 1 6 are arranged at least on one of the side surfaces 17 of the rolling body 15. The depth deviations 1 6 may be on a side surface 17 of the rolling element 15, on both side surfaces 17 of the rolling element 15 and / or on the rolling surface 18 of the rolling element 15.

In particular, a plurality of rolling elements 15 may include depth deviations 16, in particular two depth deviations. According to other embodiments, a plurality of rolling elements 15 may be provided with depth deviations 1 6, and the number of existing on the plurality of rolling elements 15 depth deviations 1 6 may be the same or different at least one rolling element 15 at each rolling element 15. According to embodiments of the invention, any number of depth deviations 1 6, on at least one side surface 17 of the rolling body 15 are attached. Furthermore, the depth deviations can be a suitable Have shape. Some examples are illustrated in FIG. These examples are for illustration only and not as a limitation of the invention. The depth deviations 1 6 z. B., inter alia, have an oval shape, circular shape or a substantially trapezoidal shape.

According to FIG. 4, z. B. two, four or eighteen depth deviations 1 6 may be present. Also other different ones are an odd number of depth deviations 1 6 is possible. Even if in the given example, the depth deviations 1 6 on the rolling elements 15 circumferentially equidistant, the; Distances between adjacent depth deviations 1 6 be different sizes.

The depth deviations 16 may be formed by locally adding material to the rolling element 15 (see FIG. 5 (a)), or in other words by locally attaching projections on the at least one rolling element 15. Also, the depth deviations 16 may be formed by locally removing material from the reel body 15 (see FIG. 5 (b)), or in other words, locally forming grooves in the at least one reel body 15. The format of the depth deviations 16 may depend on the type of sensor used. The shaft bearing assembly 10 further includes at least one sensor 19 for generating a signal when the depth deviations 16 pass it. The sensor 19 is connected to a part of the transmission, the component of which forms the shaft-bearing assembly 10, or fixed to a part of the rolling bearing 12. The sensor 19 has a scanning direction bounded by a cone whose half angle at the top is 40 °, and a center line CL of the cone is perpendicular to a plane having a tolerance of + 40 ° and -40, respectively ° is formed by the side surface 17, which includes the depth deviations 16 (see FIG. 6). In other words, the sensor 19 has a scanning direction which is perpendicular to a plane formed by the side surface 17 including the depth deviations 16 with a tolerance of + 40 ° and -40 °, respectively. The center line CL of the cone is substantially perpendicular to the plane formed by the side surface 17, which includes the depth deviations 16.

According to one embodiment of the invention, the sensor 19 may be connected by means of a connecting part 20 fixed to a part of the rolling bearing 12. The sensor 19, for example, by means of the connecting part 20 fixed to the outer ring 14 of the Rolling 12 may be connected. This is illustrated in FIG. 7. Also, the sensor 19 may be fixedly connected to an inner ring 13 of the rolling bearing 12 or a cage of the rolling bearing 12 (not shown in the figures) in a similar manner.

According to further embodiments, the sensor 19 may be fixedly connected to a part of the transmission. For example, the sensor 19 by means of connecting part 20 fixed to the gear housing 21 (see Fig. 8) or in a similar manner fixed to a shaft 1 1 of the transmission (not shown in the figures). The connecting part 20 between the gear part and the sensor 19 may be formed by a separate connecting part 20, as shown in Fig. 8, or by a connecting part 20, which is formed with the gear part to which the sensor 19, in one piece is (not shown in the figures).

According to one embodiment, the shaft 1 1 may be a planetary shaft 1 1, and the bearing 12 may serve for the storage of planetary gears 22 on the planet shaft 1 1, or in other words be a planetary gear 12. According to this particular example, the outer ring 14 of the bearing 12 can be installed in the planetary gear 22 and the sensor 19 can be fixedly connected to the inner ring 13 of the bearing 12 via the connecting part 20. This is illustrated in FIGS. 9 and 10. The difference between the two figures is the location of the sensor 19. In principle, the sensor 19 may be positioned in any position to the reel body 15, but the farther the sensor 19 is from the (indicated by dashed line) center line of the reel body 15, the better will be the sensor signal.

The sensor 19 may be any known to a person skilled in the sensor, which is suitable for detecting depth deviations 1 6. According to embodiments of the invention, the sensor 19 may include a distance sensor, such as e.g. be an eddy current sensor, or it may be a pulse generator such as e.g. be an inductive proximity switch sensor, a Hall sensor or a gear sensor. These sensors have the advantage that they can detect the presence of near ferrous objects without body contact.

According to one embodiment of the invention, the sensor 19 can detect the speed of the rolling body 15, regardless of which of the bearing rings 13, 14 rotates.

By appropriate positioning and specific choice of the sensor 19, one can measure three types of slip in one step or with the same sensor signal. lent roll body slip, cage slippage and axial slip. If, for example, the sensor 19 is fastened to the inner ring 13 or outer ring 14 of the bearing 12, the rotational speed can be determined in the moment in which the sensor passes by the rolling element 15. An advantage of this sensor positioning is that the rotational speed of the cage of the bearing 12 can be determined; As a result, the cage slip can also be calculated from the sensor signal. For example, if an eddy current sensor 19 is used, which can measure the axial displacement of the roller body 15, three slip types can be determined from only one sensor signal, namely roller body slip, cage slip and axial slip.

The present invention also provides for the use of a bearing described above according to various embodiments in order to determine the speed of at least one rolling element 15 in the bearing 12 or to determine the slippage in the bearing 12.

The following explains how to determine the slip or the speed of at least one of the rolling elements 15 according to embodiments of the invention.

Fig. 1 1 shows an example Matlab simulations for bearings 12 with rotating inner ring 13 and fixed Au ßenring 14, wherein the sensor 19 is mounted on the Au ßenring 14. The invention also applies to bearings 12 in which the inner ring 13 is fixed and the outer ring 14 rotates. The rolling element 15, for which the measurements are simulated, has 20 depth deviations 1 6, which are arranged circumferentially spaced on the rolling elements 15 from each other. Fig. 11 (a) shows the computational path of the sensor 19 in the coordinate system of the reel body 15 for different degrees of slip. The bold black line in the figure signals the path taken by the sensor 19. From left to right, simulations for slip of 0%, 33%, 67% and 100% are shown. In this case, a slip of 0% is understood to mean that the path traveled by the rolling element relative to the inner ring has no portion which is covered by sliding movement. At a slip of 10%, the proportion of the path traveled by a sliding movement in relation to the total travel of the rolling element relative to the inner ring is 0.1. For the other percentages applies accordingly. It can be seen from the figure that, depending on the degree of slip, different depth deviations 1 6 pass sensor 19. fen, This is also clear from the time signal of the sensor, which is shown in Fig. 1 1 (b). This means that the degree of slip can be determined by counting the number of pulses each time the reel body 15 passes the depth deviations 16 at the sensor 19. The measurement resolution can be increased by not only counting the number of pulses in the sensor signal, but also taking into account the length of time between the pulses. The shape of the vector time lengths is a parabola (see Fig. 11 (c)). The estimated characteristics of this parabola are used to estimate the degree of hatching.

Fig. 12 shows results from simulations for a rolling element 15 as described above with reference to Fig. 11, with random initial angle of the rolling element 15 at the moment of passing the reel body 15 on the sensor 19. The left diagram shows the number of pulses that occur at each pass of the sensor 19 on the rolling elements 15 were counted. The right diagram shows the parameter a of the parabola with the equation y = a + bx ² , calculated from the progression of the time intervals between the pulses plotted against time. Subsequently, a function of the number of pulses and the parameter a as a function of the slip is determined from these simulations. This function is shown in Fig. 12 by the bold, solid line. In the left diagram this is a straight line, in the right diagram a second order approximation is used. This function then estimates the degree of slip for the simulations. The results are shown in FIG. The estimated degree of slip from the number of pulses recorded in the signal is shown in the left diagram. This graph shows that 95% of the estimates are within 15% of the actual degree of hatching,

that is, 95% of the crosses in this diagram are less than 15% difference from the real degree of slip (straight line). Using the parameter a function of the estimated parabola yields an error of only 2% (see right diagram).

The simulations were checked experimentally. To validate the simulations, an experimental setup was set up. A roller body 15 with a diameter of 58 mm was provided with 20 depth deviations 16, which were circumferentially spacedly mounted on the reel body 15, and driven by an electric motor to represent the reel body speed. In the experiment, a gearwheel sensor attached to a pendulum was used. The rotary The speed of the pendulum was measured with an incremental encoder and represents the cage speed of the bearing.

With each passing of the sensor on the rotating reel body, the number of pulses and the time between each pulse were registered. In a similar manner as described above for the simulation, roller slip is estimated from the sensor signal. This estimate is compared to a precisely determined slip value calculated from values of measured pendulum velocity (= cage velocity) and engine velocity (roll body velocity).

The results are shown in FIGS. 14 and 15. At the level of hatching estimated from the number of pulses detected in the signal, 95% of the estimates are within 17% of the actual degree of hatching; this is comparable to the simulation result. Using the parameter a function of the estimated parabola results in a 9% error.

Claims

claims

1 . Rolling bearing (10) for a gear, wherein the rolling bearing (10) comprises a bearing inner ring (13), a bearing outer ring (14) and at least one rolling body (15),

characterized in that the rolling bearing (10) has a sensor (19) which is fixedly arranged with respect to a gear parts or a part of the rolling bearing (10) and the rolling elements (15) on at least one side surface (17) has a depth deviation (1 6) comprises, wherein the depth deviation is formed so that the side surface of the rolling body (15) along a circular path about an axis of rotation of the rolling body (15) has at least two different depths and the sensor is positioned to detect the depth deviation.

2. Rolling bearing (10) for a transmission according to the preceding claim, characterized in that a plurality of rolling bodies (15) of the rolling bearing (10) have depth deviations (1 6).

3. rolling bearing (10) according to any one of the preceding claims, characterized in that the at least one rolling body (15) has a plurality of depth deviations (1 6).

4. rolling bearing (10) according to any one of the preceding claims, characterized in that at least one of the depth deviations (1 6) is formed by a recess.

5. Rolling bearing (10) according to any one of the preceding claims, characterized in that at least one of the depth deviations (1 6) is formed by a material terial excess.

6. Rolling bearing (10) according to any one of the preceding claims, characterized in that the sensor (19) on the inner ring (13) of the rolling bearing (12), on Outer ring (14) of the rolling bearing (12) on a cage of the rolling bearing (12), on a housing of the transmission or on a shaft (1 1) of the transmission is attached.

7. rolling bearing (10) according to any one of the preceding claims, characterized in that the sensor (19) is a distance sensor, in particular an eddy current sensor, an inductive proximity sensor, a Hall sensor or a gear sensor.

8. Rolling bearing (10) according to one of the preceding claims, characterized in that the rolling bearing (10) cylindrical rolling elements, conical rolling elements, pendulum roller body or toroidal rolling elements.

9. rolling elements (15) for a rolling bearing (10) according to one of the preceding claims in particular for a transmission for a wind turbine, characterized in that the rolling body (15) has a running surface and at least one side surface, characterized in that the side surface a depth deviation has, so that the rolling body (15) along a circular line around the axis of rotation of the rolling body (15) has at least two different depths.

10. A method for determining the speed, the rotational speed and / or the slip of at least one rolling element (15) of a rolling bearing (10), characterized in that at least one rolling element (15) has different depths on a circular path about the axis of rotation and a sensor ( 19) is arranged on a part of the roller bearing (10) so that the depth deviation can be detected, wherein from the sensor signal, in particular the time interval of the sensor signals, which are dependent on a passing of the depth deviation at the sensor, the speed, the rotational speed and / or the slip is calculated.

1 1. Transmission comprising a roller bearing according to one of claims 1 to 8.

12. Use of a rolling element according to claim 9 and / or a rolling bearing in a transmission, in particular in a wind power transmission.