DE102017120594A1 - Measuring arrangement for determining at least one state variable in a rolling bearing - Google Patents

Abstract

Rolling bearings usually have an inner ring, an outer ring and arranged therebetween rolling elements, which roll on the inner ring and the outer ring. Ideally, the rolling elements should roll freely on the inner ring or on the outer ring. A measuring arrangement 3 for determining at least one state variable v1, v2, v3, n in a rolling bearing, wherein the state variable v1, v2, v3, n is an end surface velocity v1 of one of the rollers 1 in the rolling bearing, wherein the rollers 1 are rotatable about the roller axis RA and / or are movable in the circumferential direction about a bearing axis of the rolling bearing, proposed with a first sensor 4 for outputting first measurement data M1 and with a second sensors 5 for outputting second measured data M2, wherein the sensors 4, 5 can be arranged in the direction of rotation about the bearing axis one after the other by a local offset, and with an evaluation device 6, wherein the evaluation device 6 is formed by comparing the first and the second measured data M1, M2 to determine a time offset delta_tw between the first and second measurement data M1, M2 and Ba sis the temporal offset delta_tw and the local offset to determine the front surface velocity v1.

Description

The invention relates to a measuring arrangement for determining at least one state variable in a rolling bearing having the features of the preamble of claim 1.

Rolling bearings usually have an inner ring, an outer ring and arranged therebetween rolling elements, which roll on the inner ring and the outer ring. Ideally, the rolling elements should roll on the inner ring or on the outer ring without slip. Due to geometrical conditions, such as that the raceway diameter on the outer ring is greater than the inner diameter of the treadmill diameter, there is inevitably some slip. In radially loaded roller bearings, there is also a loss of "traction" in load-free zones, in which the rolling elements are loaded only insufficient, and thus to a further structure of a rolling element slippage. The rolling element slip also depends on the lubrication situation (lubricant quantity, viscosity, etc.) as well as on the load situation (dynamics, preload, etc.). The rolling element slip can be responsible for wear, lubrication and WEC damage to rolling bearings.

To determine the rolling element slip, the roller speed can be measured. The publication DE 10 2014 214 178 A1 describes a method for measuring a rotational speed of a rolling element arranged in a rolling bearing, in which by the both about its Wälzkörperachse and about a parallel rolling bearing axis rotating and with an at least partially oriented perpendicular to the rolling element axis magnetic field rolling body an alternating magnetic field is generated, the magnetic Field strength is converted by a magnetic field sensor into an electrical voltage signal which is measured at a sampling frequency and evaluated algorithmically for calculating at least one speed, wherein as part of the algorithmic evaluation, a demodulation of the sampled voltage signal is performed.

The invention has for its object to provide a measuring arrangement for determining at least the roller speed, which allows easy integration. This object is achieved by a measuring arrangement with the features of claim 1. Preferred or advantageous embodiments of the invention will become apparent from the dependent claims, the following description and the accompanying figures.

The invention relates to a measuring arrangement for determining at least one state variable in a rolling bearing. The rolling bearing is designed in particular as a roller rolling bearing and has a plurality of rollers as rolling elements. The rolling bearing defines a bearing axis. Each of the rollers defines a roller axis associated with the respective roller around which the respective roller rotates. The state variable is designed, in particular, as a measured variable or as a derived variable for describing the state, in particular the state of motion, of the rolling bearing. The at least one state variable includes at least one end surface velocity of one of the rollers in the rolling bearing. The front surface speed describes the speed of a section on the face of the roller. The front surface speed may be given in units of travel per time.

In the context of the invention, it is proposed that the measuring arrangement has at least one first sensor for outputting first measured data and a second sensor for outputting second measured data. The sensors can be arranged next to one another in the direction of rotation about the bearing axis by a local offset. Thus, a roller, in particular a roller end, in particular a section of the roller end, first of the first sensor and temporally and / or locally subsequently detected by the second sensor.

The measuring arrangement has an evaluation device, wherein the evaluation device is preferably designed as a digital data processing device, such as a computer, a microcontroller, etc. The evaluation device is designed, in particular, in terms of programming technology and / or circuitry, by comparing the first and the second measurement data, wherein the first and the second measurement data can be assigned to a common roller of the rolling bearing, to determine a time offset between the first and the second measurement data. It is assumed that the first sensor to the common role receives the same signal as the second sensor and thus the time lag can be determined. Furthermore, the evaluation device is designed based on the time offset and the local offset, which is determined by the structural arrangement of the sensors to determine the front surface speed of the common role.

The measurement signals, and thus the measurement data of two sensors arranged in succession in a particular short local distance, measured on the roller face side, mainly depend on the inhomogeneities of the material element at the measuring point. From the time that elapses until a signal peak from the first sensor reaches the second sensors, the front surface speed can be determined in particular determine the common role. The measuring signals at the sensors fluctuate high-frequency due to material or surface inhomogeneities of the roller on the roller end face. From the time lag with which such rashes or inhomogeneities from the first sensor also reach the second sensor, the front surface speed of the common roller can be determined.

In one possible implementation of the invention, the first and second measurement data are compared with each other via an autocorrelation function. The autocorrelation function determines the time interval between the first and second measurement data with respect to the common role.

In a preferred embodiment of the invention, the sensors are arranged at the same radial distance from the bearing axis. Alternatively or additionally, the sensors are at the same distance from the roller end side. Characterized in that the measurement conditions are the same for each of the sensors with respect to the common role, the measurement accuracy of the measuring arrangement is improved.

It is particularly preferred that a measuring axis of the sensors is arranged in each case offset relative to the roller axis. For example, the measuring axes of the sensors are arranged at a different radial distance and / or on a different pitch circle diameter than the roller axes.

In principle, the sensors can be of any desired design and thus, for example, be implemented as optical sensors or magnetostrictive sensors. These are particularly preferably designed as eddy-current sensors. Eddy current sensors are particularly suitable as the sensors, since they are insensitive to oil, water, dust, etc., and are thus insensitive to substances present between the eddy current sensors and the rollers. The measuring signals, and thus the measured data of two eddy current sensors arranged in a short local distance one behind the other, depend on the magnetic inhomogeneities of the roller or the roller end at the measuring point. From the time that elapses until a signal peak from the first eddy current sensor reaches the second eddy current sensors, the front surface speed, in particular of the common roller, can be determined. The measuring signals at the eddy current sensors fluctuate high frequency due to material inhomogeneities of the roller on the roller end side. From the time offset with which such deflections or inhomogeneities from the first eddy current sensor also reach the second eddy current sensor, the end surface velocity of the common roller can be determined.

In a preferred embodiment of the invention, the evaluation device is designed in particular programmatically and / or circuitry to determine from the first and / or from the second measurement data a time offset between two consecutive roles or a time offset between two pockets of a cage of the bearing. While the determination of the front surface velocity is based on the inhomogeneities of the roll or the end of the roll and the resulting signal fluctuations in the first and / or second measurement data, the time offset between two consecutive rolls and / or between two successive windows can be very simple and clear from the first or alternatively derived from the second or from the first and second measurement data.

In a preferred embodiment of the invention, the evaluation device is designed in particular programmatically and / or circuitry, based on the geometric, in particular constructive sizes of the rolling bearing and the time offset between two consecutive pockets and / or between two consecutive roles a circulating speed of the rollers and / or Cage (cage speed) to determine the bearing axis as a state variable.

In a preferred embodiment of the invention, the evaluation device is designed in particular programmatically and / or circuitry, based on the front surface speed and the rotational speed to determine a roller speed of the particular common role in the rolling bearing as a state variable.

In a preferred embodiment of the invention, the measuring arrangement comprises the rolling bearing, wherein the sensors are arranged in the direction of rotation about the bearing axis by a local offset successively, as previously described.

Particularly preferably, the rolling bearing is designed as a rolling bearing with a pitch circle diameter> 500 mm, preferably> 1000 mm. Particularly preferably, the rolling bearing is used as a rotor bearing in a wind turbine.

• 1 eine schematische Darstellung einer Messanordnung als ein Ausführungsbeispiel der Erfindung sowie Signaldiagramme zur Erläuterung der Funktionsweise der Messanordnung.

Further features, effects and advantages of the invention will become apparent from the following description of a preferred embodiment of the invention and the accompanying figures. These show:

• 1 a schematic representation of a measuring arrangement as an embodiment of the invention and signal diagrams for explaining the operation of the measuring arrangement.

The 1 shows a roller in a schematic axial plan view 1 or a roller end 2 of the roller of a rolling bearing, not shown, which is designed as a radial roller bearing. The rolling bearing comprises an inner ring and an outer ring, wherein a plurality of such rollers 1 are arranged rolling between the inner ring and the outer ring. Furthermore, the roller bearing on a likewise not shown cage, wherein the rollers 1 are guided in the cage. For this purpose, the cage has windows in which the rollers 1 are inserted.

To measure the roll speed, that is the number of rotations of the roll 1 around its own roller axis RA , is a measuring arrangement 3 provided, which a first sensor 4 and a second sensor 5 as well as an evaluation device 6 having. The sensors 4, 5 are formed as eddy current sensors and data technology and / or signaling technology with the measuring arrangement 3 connected, so that these first and second measurement data to the evaluation 6 can pass .. The sensors 4 . 5 are in the 1 only roughly schematized shown as ovals. The sensors 4 . 5 are with their measuring axes parallel to the roller axis RA aligned. However, the measuring axes of the sensors 4, 5 are offset parallel to the roller axis RA arranged. The distances between the sensors 4 . 5 and the forehead 2 the role 1 are with both sensors 4 . 5 equal. The role 1 is formed of a metallic material, in particular of rolling steel.

With a rotation of the roll 1 on the one hand around its own roller axis RA and on the other hand around a bearing axis of the bearing take the sensors 4 . 5 Measuring signals, which high frequency due to material inhomogeneities of the role 1 or the roller end 2 fluctuate. These high-frequency fluctuations provide a kind of identification feature, such as a fingerprint, around a specific section on the roller end 7 of the roller 1 to be able to identify. Two exemplary measurement signals are schematically as first measurement data M1 and second measurement data M2 on the left in the 1 shown. It can be seen that the measured data M1 and M2 have the same high-frequency fluctuations, but are separated by the time delta_tw and thus by the time offset of delta_tw. The temporal offset delta_tw can be determined, for example, by an autocorrelation function AK.

On the basis of the time offset delta_tw, an end surface velocity v1 can be calculated. The front surface speed v1 is composed of the rotational speed of the roller 1 around the roller axis RA and from the rotational speed v2 the role 1 around the bearing axis of the rolling bearing.

In order to be able to calculate the roller speed from the front surface speed, it is thus necessary to calculate the revolution speed v2 or, equivalently, to determine a cage speed or a cage speed. On the right side are the measurement data M1 and M2 shown in a larger time scale. It can be seen that for each passing role 1 a peak P1 . P2 can be seen. By the temporal distance of the peaks P1 in the measured data M1 (t1) or by the time interval of the peaks P2 in the measured data M2 (t2) or by the time interval between a peak P1 from the measured data M1 and a peak P2 from the measured data M2 can be the speed of rotation of the rollers 1 and / or determine the rotational speed of the cage. In other words, a slightly time-delayed measurement signal is produced at the sensors 4, 5. From the time intervals between the two measuring signals at a sensor (t1, t2) or the time offset of the measuring signals at the sensor 4 . 5 (delta_tK) can at a known distance of two cage pockets or the two sensors 4 . 5 the cage speed and the surface speed v2 and thus the rotational speed in the center of the roller 1 are determined due to the cage rotation.

berechnen. Aus der Rollendrehzahl n kann - in Kenntnis der Drehzahlen des Innenrings und/oder des Außenrings im Weiteren der Wälzkörper-Schlupf berechnet werden.The evaluation device 6 is formed, the front surface speed v1 as well as the circulation speed v2 to calculate or determine. In a next step will depend on the position of the sensors 4 . 5 the front surface speed v1 from the revolution speed v2 - In this embodiment, by subtraction - adjusted .. Pulls from this frontal surface velocity v1, the speed due to the cage movement v2 From, you get the speed v3 in the place of the sensors 4 . 5 solely due to the roll rotation around its own roll axis. With known radius r_Sensor of the sensors 4 . 5 to the roll center or to the roll axis RA can be followed by the roller speed on the formula $$\text{n}=\text{<figure-callout id="3" label="v" filenames="DE102017120594A1\_0002.png" state="{{state}}">v</figure-callout>}3\text{/}\left(2*\text{pi}*\text{r}\_\text{sensor}\right)$$

to calculate. From the roller speed n can be calculated - knowing the speeds of the inner ring and / or the outer ring below the rolling element slip.

The measurement signals from the two arranged in quick succession, on the roller face 2 measuring eddy current sensors as sensors 4 . 5 depend mainly on the magnetic inhomogeneity of the material element at the measuring point, since the distance to the roller 1 is about the same. From the time that elapses until a signal peak from the sensor 4 the sensor 5 achieved, can the Calculate front surface speed. The measurement position is deliberately outside the role center. From the frequency, with the roles 1 at the sensors 4 . 5 or frequency sensor overdrive, the cage speed and thus the surface speed in the center of the role 1 be calculated. From the two surface speeds v1 and v2 can then be the roller speed n and optionally the roller slip can be calculated. Knowing the position of the load zone and the speed of the inner ring and outer ring can predict the role of rotational speed over the circumference. Alternatively, the measurement of the roller speed n at several circumferential positions possible to have multiple support points for the calculation of a roller speed curve.

LIST OF REFERENCE NUMBERS

1

role

2

roller end

3

measuring arrangement

4

first sensor

5

second sensor

6

evaluation

RA

roller axis

M1, M2

measurement data

P1, P2

peaks

t

Time

v1

Surface speed of the roll at sensor position

v2

Circulation speed of the roller and / or the cage around the bearing axis and / or surface speed of the roller on the bearing axis

v3

Surface speed of the roll at sensor position in the direction of rotation about the roll axis

n

Roller speed around the roller axis

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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

• DE 102014214178 A1 [0003]

Claims (9)

Measuring arrangement (3) for determining at least one state variable (v1, v2, v3, n) in a roller bearing, wherein the state variable (v1, v2, v3, n) is an end surface speed (v1) of one of the rollers (1) in the rolling bearing comprises, wherein the rollers (1) are rotatable about the roller axis (RA) and / or are movable in the direction of rotation about a bearing axis of the rolling bearing, characterized by a first sensor (4) for outputting first measurement data (M1) and by a second sensor (5) for outputting second measurement data (M2), wherein the sensors (4, 5) can be arranged successively in the direction of rotation about the bearing axis by a local offset, and by an evaluation device (6), wherein the evaluation device (6) is formed, by comparing the first and the second measurement data (M1, M2) to determine a time offset (delta_tw) between the first and the second measurement data (M1, M2) and the S based on the time offset (delta_tw) and the local offset to determine the surface velocity (v1). Measuring arrangement (3) according to Claim 1 , characterized in that the sensors (4, 5) in the same radial distance (r_sensor) are arranged to the bearing axis. Measuring arrangement (3) according to Claim 1 or 2 , characterized in that a measuring axis of the sensors (4,5) each offset from the roller axis (RA) are arranged. Measuring arrangement (3) according to one of the preceding claims, characterized in that the sensors (4,5) are designed as eddy current sensors. Measuring arrangement (3) according to one of the preceding claims, characterized in that the evaluation device (6) is formed from the first and / or second measurement data (M1, M2) a time offset between two successive roles or a time offset between two pockets determined by a cage of the rolling bearing. Measuring arrangement (3) according to Claim 5 , characterized in that the evaluation device (6) is designed to determine a rotational speed (v2) of the rollers and / or of the cage about the bearing axis on the basis of the geometric variables of the roller bearing and the time offset. Measuring arrangement (3) according to Claim 6 , characterized in that the evaluation device (6) is designed to determine a roller speed (n) in the rolling bearing on the basis of the front surface speed (v1) and the rotational speed (v2). Measuring arrangement (3) according to one of the preceding claims, characterized in that the measuring arrangement (3) comprises the rolling bearing and that the sensors (4,5) are arranged in the direction of rotation about the bearing axis by a local offset succession. Measuring arrangement (3) according to Claim 8 , characterized in that the rolling bearing is designed as a large roller bearing with a pitch circle diameter greater than 500 mm, preferably greater than 1000 mm.

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