PROCESS FOR DETERMINING THE RELIABILITY OF A SENSORIZED ROLLER BEARING

Abstract

A process for determining the reliability of a sensorized bearing configured to measure load and speed is provided. The process includes the following steps. Bearing load and rotational speed are determined from data acquired from the sensorized bearing. Next, an array linking the determined load to the determined n.dm value is filled until that all available loads are parsed. Then a L10 life is determined for each load within a distribution based on the array. Finally, an overall L10 life is determined based on the Palmgren-Minor rule. The load distribution and the L10 lives a bearing reliability R for a given date is determined based on a Weibull curve and the overall L10 life.

Claims

1. A process for determining the reliability of a sensorized roller bearing provided with an inner ring, with an outer ring and with at least one row of rollers comprising at least one sensorized roller, the at least one sensorized roller being configured to measure at least load and speed, the process comprising the following steps: bearing load and rotational speed are determined from data acquired from the at least one sensorized roller, a n.dm value is determined as being equal to the rotation speed times the mean diameter of the roller bearing, an entry is filed in an array, linking the determined load to the determined n.dm value, the n.dm values are aggregated over all the measurements, those steps are performed in a loop until that all available loads are parsed resulting in a load distribution, then the process resumes with the following steps: a distribution linking the percentage of occurrences versus each load is calculated based on the array, then a L10 life is determined for each load within the distribution, and an overall L10 life is determined based on the Palmgren-Minor rule, the load distribution and the L10 lives, and a bearing reliability R for a given date is determined based on the Weibull curve and the overall L10 life.

2. The process according to claim 1, wherein the sensorized roller bearing comprises at least first and second rows of rollers, each row comprising at least one sensorized roller, bearing load and rotational speed being determined from data acquired from the sensorized rollers of the first and second rows.

3. The process according to claim 1, wherein the date for determining the reliability is any point of time, past, present or future.

4. The process according to claim 1, wherein bearing temperature is determined from data acquired from the at least one sensorized roller.

5. A process for controlling a wind turbine having a main shaft supported by at least one sensorized roller bearing, wherein the operating parameters of the wind turbine are adjusted based on the L10 life and the determined reliability of a sensorized roller bearing provided with an inner ring, with an outer ring and with at least one row of rollers comprising at least one sensorized roller, the at least one sensorized roller being configured to measure at least load and speed, the process comprising the following steps: bearing load and rotational speed are determined from data acquired from the at least one sensorized roller, a n.dm value is determined as being equal to the rotation speed times the mean diameter of the roller bearing, an entry is filed in an array, linking the determined load to the determined n.dm value, the n.dm values are aggregated over all the measurements, those steps are performed in a loop until that all available loads are parsed resulting in a load distribution, then the process resumes with the following steps: a distribution linking the percentage of occurrences versus each load is calculated based on the array, then a L10 life is determined for each load within the distribution, and an overall L10 life is determined based on the Palmgren-Minor rule, the load distribution and the L10 lives, and a bearing reliability R for a given date is determined based on the Weibull curve and the overall L10 life.

6. The process according to claim 5, wherein the reliability is determined for several dates in the future, the reliability for each date is then compared to a threshold and maintenance is planned for the first date associated with a reliability lower than the threshold.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0045] At least one of the embodiments of the present invention is accurately represented by this application's drawings which are relied on to illustrate such embodiment(s) to scale and the drawings are relied on to illustrate the relative size, proportions, and positioning of the individual components of the present invention accurately relative to each other and relative to the overall embodiment(s). Those of ordinary skill in the art will appreciate from this disclosure that the present invention is not limited to the scaled drawings and that the illustrated proportions, scale, and relative positioning can be varied without departing from the scope of the present invention as set forth in the broadest descriptions set forth in any portion of the originally filed specification and/or drawings. The present invention will be better understood from studying the detailed description of a number of embodiments considered by way of entirely non-limiting examples and illustrated by the attached drawing in which:

[0046] FIG. 1 shows the main components of a sensorized bearing,

[0047] FIG. 2 shows the main steps of a process according to the invention, and

[0048] FIG. 3 shows the geometric relationship between the forces applied to the rollers and the forces applied on the bearing.

[0049] FIG. 4 shows a process for controlling a wind turbine according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0050] Those of ordinary skill in the art will appreciate from this disclosure that when a range is provided such as (for example) an angle/distance/number/weight/volume/spacing being between one (1 of the appropriate unit) and ten (10 of the appropriate units) that specific support is provided by the specification to identify any number within the range as being disclosed for use with a preferred embodiment. For example, the recitation of a percentage of copper between one percent (1%) and twenty percent (20%) provides specific support for a preferred embodiment having two point three percent (2.3%) copper even if not separately listed herein and thus provides support for claiming a preferred embodiment having two point three percent (2.3%) copper. By way of an additional example, a recitation in the claims and/or in portions of an element moving along an arcuate path by at least twenty) (20° degrees, provides specific literal support for any angle greater than twenty)(20° degrees, such as twenty-three)(23° degrees, thirty)(30° degrees, thirty-three-point five)(33.5° degrees, forty-five) (45° degrees, fifty-two)(52° degrees, or the like and thus provides support for claiming a preferred embodiment with the element moving along the arcuate path thirty-three-point five)(33.5° degrees. In order to solve the aforementioned drawbacks, the inventors got the idea to use the data provided by a sensorized bearing in order to estimate the bearing reliability. Documents DE201810200047, DE201610211779 and DE201810200048 disclose different examples of such a sensorized bearing. In particular, the determination of a bearing reliability can be applied to a wind turbine where the main shaft bearing is a sensorized bearing.

[0051] Thanks to the data available through the sensorized bearing, the load frequency can be updated and a new overall L10 life can be calculated.

[0052] Based on the overall L10 life and the turbine operation duration, the current reliability of the main shaft bearing can be calculated using the Weibull curve.

[0053] FIG. 1 illustrates a sensorized bearing 1, similar to a conventional bearing and of a roller bearing type. The sensorized bearing 1 comprises an inner ring, an outer ring, first and second row of rollers arranged between raceways provided on the inner and outer rings. The rollers may be tapered, spherical or cylindrical rollers.

[0054] The sensorized bearing differs from a conventional bearing in that one roller 2 in the first row and one roller 3 in the second row are each embedded with sensors for determining forces Fr1 and Fr2 applied respectively on their surface along with their rotation speed and, eventually temperature. In the illustrated example, the sensorized roller 2 axially faces the sensorized roller 3.

[0055] A process for determining the reliability of the sensorized bearing is illustrated by FIG. 2.

[0056] During a first step 11, bearing temperature, load and rotational speed are determined out of data acquired from the sensorized rollers.

[0057] Bearing temperature is determined based on a model out of the sensorized rollers measured temperature and the geometry of the bearing.

[0058] Similarly, bearing rotational speed is determined based on a model out of the sensorized rollers measured rotational speed and the geometry of the bearing.

[0059] Radial and axial bearing loads are determined first by projecting roller forces onto the radial and axial directions. FIG. 3 illustrates the position of the sensorized roller 2 and the position of the sensorized roller 3 in respect to bearing center C along with the applied forces Fr1, Fr2 and the resulting loads Fx, Fy, Fz in an orthonormal frame.

[0060] Based on the measured roller forces Fr1 and Fr2 in the two raceways, the axial load Fx can be determined based on the following equation:

Fx=(Fr2−Fr1)*cos (∈)

[0061] where ∈ is n/2—the contact angle of the roller to the raceway.

[0062] Two radial loads Fy, Fz can be determined based on the following equations:

Fy=(Fr1+Fr2)*sin(∈)*sin(θ)

Fz=(Fr1+Fr2)*sin(∈)*cos(θ)

[0063] where θ is the angle of the roller around the circumference of the bearing.

[0064] In the present invention, θ is chosen equal to 0 so that the radial load considered is the vertical load comprised in a plane extending in between the sensorized rollers.

[0065] In order to determine the moments Mx and My, the distance L between the applied load locus and the bearing center of rotation and the angle A between the applied load direction and the direction extending between the applied load locus and the bearing center of rotation are determined thanks to the following equations:

A=∈−atan(W/P)

L=√{square root over (P.sup.2+W.sup.2)}

[0066] Where:

[0067] W is the width from center of the bearing to the roller

[0068] P is the pitch radius

[0069] The moments Mx and My are determined by applying the following equations:

Mx=(Fr2−Fr1)*cos(A)*L*cos(θ)

My=(Fr2−Fr1)*cos(A)*L*sin(θ)

[0070] It is reminded that θ is chosen equal to 0. My is then equal to 0.

[0071] Once the radial and axial forces and moment are determined for the pair of sensorized rollers, the corresponding values for the bearing can be determined through integration or summation on a full ring of rollers.

[0072] During a second step 12, the n.dm value is determined as being equal to the rotation speed times the mean diameter of the bearing.

[0073] During a third step 13, an entry is filed in an array, linking the current loads to the n.dm value.

[0074] Steps 11 to 13 are performed in a loop so that all available loads are parsed.

[0075] During a fourth step 14, a distribution linking the percentage of occurrences versus each load is calculated based on the array. A L10 life is determined for each load within the distribution. The overall L10 life is then determined based on the Palmgren-Minor rule and the load distribution.

[0076] During a fifth step 15, the reliability R for a given date is determined based on the Weibull curve and the overall L10 life. The instant can be any point of time, past, present or future.

[0077] A process for controlling a wind turbine in order to optimize the main shaft bearing life and operation of the wind turbine comprises the following steps and is illustrated by the FIG. 4.

[0078] Steps 11 to 15 are similar to those described above in relation with the process for determining the reliability of a sensorized bearing. After the fifth step 15, the present process continues with a sixth step 16, during which the operating parameters of the wind turbine are adjusted based on the L10 life and the current reliability.

[0079] Alternatively, during the sixth step 16, the reliability is determined for several dates in the future. The reliability for each date is then compared to a threshold and maintenance is planned for the first date associated with a reliability lower than the threshold.

[0080] In a particular embodiment, only one sensorized roller is present or considered for determination of the loads, rotational speed and temperature. Depending of the sensorized roller present or active, load Fr1 or Fr2 are considered equal to zero in the aforementioned equations. In another embodiment, the rolling bearing comprises only one single row of rollers with at least one sensorized roller.