The disclosure relates to a rolling bearing arrangement for a transmission that, in particular, is designed for a wind turbine, comprising a rolling bearing having an outer ring, an inner ring and a multiplicity of rolling bodies rolling between the outer ring and the inner ring, wherein the outer ring and/or the inner ring have/has at least one sensor element for sensing and monitoring a state variable. The disclosure additionally relates to a wind turbine having the aforementioned rolling bearing arrangement, and to the use of the rolling bearing arrangement in a wind turbine.
In the case of wind turbine transmissions, sensors, for measuring differing state variables such as, for example, vibrations, temperatures and rotational speeds, are used to monitor the state of transmission elements. The sensors are usually attached to easily accessible locations on the transmission housing, and are connected by cables to an evaluation unit, in which the signals undergo further processing.
Known from DE 10 2011 087 471 A1 is a component having a material recess, and having a material element that includes at least one sensor. The material element is force-fitted into the material recess, and closes off the material recess in a flush manner, at least on one side. The sensor is designed to measure the forces acting upon the component and, in particular, the measure the deformations of the component.
The object of the present disclosure consists in further developing a rolling bearing arrangement for a transmission.
This object is achieved by one or more of the features according to the disclosure. Advantageous developments are given by claims, the description and the figures.
A rolling bearing arrangement according to the disclosure for a transmission of a wind turbine comprises a rolling bearing having an outer ring, an inner ring and a multiplicity of rolling bodies rolling between the outer ring and the inner ring, wherein the outer ring and/or the inner ring have/has at least one sensor element for sensing and monitoring a state variable, wherein the at least one sensor element comprises a load measuring bolt having at least one strain gauge, wherein the at least one sensor element is positioned directly in a force flow path of the state variable, wherein the state variable is at least a bearing preload of the rolling bearing.
The load measuring bolt of the sensor element is preferably produced mechanically, and preferably made of a metallic material. The metallic material, in particular, has the same coefficient of expansion as the material of the inner ring and/or of the outer ring. The metallic material is therefore preferably a bearing steel. In addition, the load measuring bolt is realized, for example, in the form of a cylinder, with alternative geometries also being conceivable. The at least one strain gauge is, for example, adhesive-bonded onto a defined surface of the load measuring bolt or applied using a coating, the at least one strain gauge being arranged, for example, on an end face and/or a lateral face of the load measuring bolt. For example, temperature-induced resistance changes may be measured by a strain gauge arranged on the lateral face of the load measuring bolt. A strain gauge arranged on the end face of the load measuring bolt may measure, for example, strain-induced resistance changes caused by compression.
The rolling bearing arrangement according to the disclosure may alternatively also be provided for a main bearing assembly, in particular for a main bearing assembly of a shaft. The rolling bearing is realized, in particular, as a tapered-roller bearing. In addition, however, the rolling bearing may also be realized as a cylindrical-roller bearing, or other rolling bearing.
Permanent or intermittent sensing of the sensor measurement values of the load measuring bolts during operation makes it possible, for example, to deduce the currently existing preload of the rolling bearing arrangement. The sensor measurement values of the load measuring bolts are therefore a measure of the bearing preload. The bearing preload is sometimes an influence parameter for the service life of a rolling bearing. For example, by taking into account the actually prevailing bearing preload, a calculation of service life can be performed while the bearing is in operation, and a continuously updated prognosis of impending bearing damage can be effected.
The term force flow path describes the course of the preload force introduced into the bearing system of the rolling bearing arrangement, the preload force being generated, for example, by the tightening of a screw on the bearing ring. The preload force is supported on the housing of the transmission, the at least one sensor element being arranged radially on one of the preloaded components such as for example, the inner ring, the outer ring or an adjusting ring, in order to detect strain-induced resistance changes. The preload force may additionally be supported on the structure surrounding the rolling bearing arrangement, for example on a shaft or a bearing housing. Alternatively, the sensor element may be arranged on another preloaded component of the rolling bearing arrangement.
Preferably, the at least one sensor element is accommodated, at least partly, in a respective radial recess of the inner ring and/or of the outer ring. The recess is realized so as to complement the geometry of the load measuring bolt, such that a force-fitting and form-fitting connection is formed between the load measuring bolt, inserted into the recess, and the inner wall of the recess. Alternatively, the load measuring bolt may be cemented into the recess.
Preferably, the respective recess is realized on the inner circumferential surface of the inner ring. The simplified cable routing of the at least one strain gauge, to a signal processing device or to a receiver, for the purpose of communicating the measured data, is advantageous. The communication may be effected both by cable and wirelessly. In the case of wireless communication, the energy supply to the strain gauge may be effected, for example, by a rechargeable battery or so-called energy harvesting. For example, in the case of energy harvesting, energy is generated from vibrations, air flows, rotational energy, temperature differences or light. Alternatively, the energy supply may also be effected inductively or capacitively.
Furthermore, preferably, three recesses, having a respective sensor element accommodated therein, are realized in a uniformly distributed manner on a circumferential surface of the inner ring and/or of the outer ring. In other words, the recesses, with a respective sensor element accommodated therein, are realized in a uniformly distributed manner, at an angle of 120° in relation to each other, on the circumference of the inner ring and/or of the outer ring. In addition, it is also conceivable for more or fewer sensor elements to be arranged in a uniformly or non-uniformly distributed manner on the circumferential surface of the inner ring and/or of the outer ring.
In a further preferred embodiment, the at least one sensor element is arranged on an adjusting ring. Preferably, the adjusting ring has a respective radially realized recess, for at least partly receiving the at least one sensor element. The adjusting ring bears axially against the rolling bearing, in particular against the inner ring or the outer ring, and may be screw-connected to produce a preload force. The sensor element arranged in the adjusting ring may be used, for example, to measure and monitor the bearing preload force.
The disclosure includes the technical teaching that the at least one strain gauge is realized by a coating. In particular, the strain gauge is realized as a thin-film sensor, which is preferably protected by a protective layer, additionally applied to the strain gauge, against mechanical influences. The coating for realizing the strain gauge is processed, for example, using a laser.
Preferably, the outer ring and/or the inner ring have/has at least two sensor elements for temperature compensation. The temperature compensation is effected directly on the load measuring bolt. For example, the error caused by the effect of temperature can be precluded by arranging the strain gauges on the end face and on the lateral face of the load measuring bolt, and interconnecting the strain gauges in a half-bridge.
Two preferred exemplary embodiments of the disclosure are described in the following on the basis of the three drawings, in which elements that are the same or similar are denoted by the same reference numerals. Shown are:
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The disclosure is not limited to the previously described exemplary embodiment. Further exemplary embodiments or development possibilities are given, in particular, by the claims or the description.
Number | Date | Country | Kind |
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102017111745.8 | May 2017 | DE | national |
This application is a 371 National Phase of PCT/DE2018/100332, filed Apr. 11, 2018, which claims the benefit of German Patent Application No. 10 2017 111 745.8, filed May 30, 2017, both of which are incorporated by reference herein as if fully set forth.
Filing Document | Filing Date | Country | Kind |
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PCT/DE2018/100332 | 4/11/2018 | WO | 00 |