KR101478078B1 - Wear-monitoring of a gearbox in a power station - Google Patents

Abstract

The present invention relates to a method for monitoring the wear of a gearbox in a power plant such as a windmill, aberration or tidal power plant, wherein the gearbox comprises at least two shafts, gears and bearings as components of the gearbox. The method includes the steps of sensing an angular position in the shafts by a rotary shaft encoder, monitoring wear of the transfer-unit in accordance with differences in sensed angular positions, in a state indicative of wear of the gearbox And generating a signal. Wherein the monitoring step further comprises sensing additional degrees of freedom of at least one of the shafts caused by wear of at least one of the components of the gearbox, particularly additional of axial and / or eccentric displacement, And generating a status signal in accordance with differences and displacements.

Description

[0001] Wear-monitoring of a gearbox in a power plant [0002]

The present invention generally relates to a method for monitoring the wear of a gearbox in a power plant according to the preamble of claim 1 and to a gearbox monitoring apparatus according to the preamble of claim 10.

Wind power plants - also called windmills - are a promising source of renewable energy already available in the market. Many windmills are crowded in wind parks or wind farms, often located in windy areas. A classic design includes a tower with a nacelle that is horizontally rotatable on top, in which a rotor with propeller blades is arranged or an electric generator is located.

In windmill applications, it is necessary for the gearboxes to turn the rotor-blade rotation at an operating speed of approximately 6 to 20 revolutions per minute (RPM) into an electric generator operating in the range of approximately 900 to 2000 RPM. Since spur gears generally allow a gear ratio of up to about 1: 5 per stage, multiple gear stages are required to achieve the required gearing ratio. Because of the efficiency, size, noise and cost considerations to reduce the number of stages and gearwheels, and also because of the considerations of power, size, noise and cost, at least one planetary gear stage having a high gear ratio can be alternately equipped. Combinations of oil and spur stages are also used.

Wind farms often operate in the megawatt range and are designed for lifetimes of more than 20 years. Although the efficiency of such gearboxes is quite high (e.g., about 98%), in terms of megawatts of power delivered, the gearbox itself or the oil therein must be actively cooled in many instances. Long lifetime also means hundreds of millions of rotor rotations and billions of rotations of generators. Similar applications also include slowly rotating input shafts that require gearing up, such as waterwheels, tidal power plants, etc., with similar operating conditions other than the above-mentioned windmills Are gearboxes at other low speed power plants. Apart from a considerably long lifetime, the load of such a windmill can change over a wide range and quickly, especially in the case of emergency stop or flurry, squall or gust of wind. Load control can be achieved by varying the angle of attack of the blades or by a horizontal rotation of the entire nacelle, but these adjustments are slow compared to possible changes in wind speed. Also, the environmental and climatic conditions of the nacelle are not desirable for operating the machinery. The above facts show that the windmill gearbox will require servicing during run-time.

There are quite complex ways to determine the predictable run time of the gearbox during the design phase. These calculations are based on predicted loads and statistical data and experiences. Due to uncertainties in actual load profiles, manufacturing tolerances and often harsh environmental conditions during run-time, these calculations can only be used to determine a preventive maintenance plan, including a considerable safety margin . Certain unexpected impacts during run time, such as peak loads, temperature cycles, manufacturing inaccuracies, and the like - if not detected - unexpected gearbox failure such as jamming or spinning And all the side effects that may arise therefrom.

In windmills, the gearbox is usually placed in a nacelle, which is higher than the ground level, and therefore it is difficult to service or repair the gearbox or its parts. Accessing it is difficult, especially because windmills are often located in remote areas, on mountains, or even on the coast. In many cases, the helicopter needs to supply space parts to the nacelle.

In particular, maintenance and replacement of the gearboxes can be quite cost-intensive, so long before the actual life is over, these tasks can be repaired based on the determined actual conditions of the gearbox, And / or replacement plans.

A known method for estimating the conditions of the gearbox is to analyze the oil inside the gearbox for wear, especially for grazed metal particles. In addition to cyclical manual analysis, there are also known in-line sensors. For example, the device disclosed in KR 2007024230 will provide a condition signal and warning if the oil analysis result is in a critical state - as an indication of worn gear wheels.

Another way that has been done manually by a skilled craftsman for a long time is to "listen" to the sound emitted by the gearbox. In automation systems, this can be done by acoustic analysis or by vibrations or acceleration sensors of some sort of microphone. Publications US 2008/0234964, CN 101 196 174 or US 5,661,659 relate to wear detection systems for mechanical systems such as gear boxes by structural acoustic or vibration analysis. Publication US 2007/0118333 discloses an anomaly detection system wherein acoustic sensors for detecting anomalies in gearbox sounds are included in the bearing unit.

In WO 2004/034010 a method for quality monitoring in the manufacture of gearboxes is presented. This is accomplished by monitoring two interacting gear wheels by two synchronously sampled rotary transducers attached to the gear wheel shafts after assembly of the gearbox. There, backlash of the gearing is determined by measurements in the forward and backward modes which provide an indication of the quality of the gearbox.

In US 6,175,793, the steering wheel gearbox of the vehicle is similar to the one in the input and output shafts of the gearbox, but is monitored by the respective position sensing means and torque sensing unit. A mathematical cancellation of torque related torsions generates a signal indicative of wear of the gear wheels in the gearbox.

JP 58 034333 relates to the invariably monitoring of stress conditions in diaphragm coupling based on the axial displacement, rotational speed and load of the power plant. This is done by means of detecting the degree of axial displacement near the fitting portion of the diaphragm coupling to the generator shaft. Based on the displacement, rotational speed and load of the power plant, the stresses in the diaphragm coupling are calculated and the safe operating state of the coupling is determined.

Although some wear effects can be deduced from the rotational position data, the wear information contained in the rotational data is incomplete and the evaluation of these data is based on experience. The clearance or backlash of the teeth of the gear wheels can be estimated with great precision, but many wear effects in the gearbox can not be deduced from the rotational position offsets. If only the angular measurements are analyzed, wear which is not visible at angular positions and which is primarily indicative of itself in other influences can not be detected.

Therefore, a more reliable basis for determining the state of the gearbox is desirable. The above-mentioned noise measurements may cover a wider range of wear effects, but are generally not highly accurate and also involve different setup-specific configurations and guesswork for each example of the gearbox. In addition, desired management of the entire system, including precise load monitoring, and taking into account actual load conditions and lifetime - or lifetime - management dependencies of critical system parts, is not feasible with acoustic analysis alone. False detections are a large cost problem, especially if there are false positives or false negative detections, especially for large machines that are difficult to access, such as those in windmill towers. In many important applications, his own acoustic analysis is not reliable or precise enough for independent use.

It is an object of the present invention to provide improved lifetime management of wind power plants by precise and reliable wear monitoring of gearboxes, as one of the most lifetime-critical parts.

It is therefore an object of the present invention to more reliably monitor the gearbox of a windmill system.

It is a further object of the present invention to provide an improved method and system for monitoring abrasion during the entire gearbox run-time, particularly in monitoring, including full set-up with gear wheels, shafts and bearings.

Another object of the present invention is to allow a more precise determination of the type and position of the worn portion in the gearbox, particularly providing all-or at least condition-status data for the most important components of the gearbox.

It is an object of the present invention to include a wide spectral range of wear indications for monitoring low frequency ranges, especially starting from the DC level.

The present invention relates to a method for monitoring the wear of a gearbox in a wind power plant. The gearbox comprises at least one first shaft, at least one second shaft, toothed wheels and bearings as components of the gearbox.

The method includes sensing a first angular position at a first shaft by a first rotary shaft encoder - as a first degree of freedom - and sensing a second angular position at a second shaft by a second rotary shaft encoder Do. Monitoring the wear of the gearbox is done in accordance with the differences in the sensed angular positions of the shafts and a state-signal is generated indicative of wear of the transfer-unit in accordance with the monitored differences.

This method is particularly suitable for the additional detection of additional degrees of freedom of at least one of the shafts, in particular of axial and / or eccentric displacement, caused by wear of at least one of the components of the gearbox, Monitoring the degree of freedom of at least two degrees of freedom, and generating a state-signal in accordance with differences and displacements in at least two degrees of freedom, especially at least one angle and at least one linear degree of freedom.

By analyzing the rotational positions of the input and output shafts of the gearbox and comparing these measurements, an indication of wear in the form of backlash or clearance and tooth wear or breakage can be evaluated. Clearance or backlash occurs especially when moving the direction of rotation. Signal disturbances due to tooth-errors have rotational periodicity. If an error does not occur on the measuring shaft, but occurs, for example, on an intermediate stage gear wheel, it is scaled by the gear transmission ratio.

In particular, if the torque-load of the gearbox is also measured and the torque-related angular displacement effects compensated, the wear effects mentioned above are represented by the angular displacement differences of the shafts relative to each other. By incorporating the shape of the internal components and knowledge of the materials, the theoretical behavior of the gearbox under load and dynamics can be predicted and the dynamic performance of the gearbox or its specific parts can be derived and monitored .

With the knowledge of the strength of the shaft and with the intermediate torque load shaft section - the two angle encoders on a single shaft can be used to determine the torque in accordance with the torsion or angular twist of the shaft under load. Thus, things such as peak torque, the number of times the torque exceeds a limit, the number of load cycles, etc. can be recorded, evaluated and monitored. This can be done separately for one or more axes. By angular position measurement, the rotational speed of the axis is also known, and the transmitted power can be calculated by torque and speed. If the power on the input and output shafts is determined, the efficiency of the gearbox, or even the efficiency of each of the internal stages, can be calculated by the two encoders on each axis. Variations for the torsion of the shaft within one revolution may also be indicative of wear. A well running gear will have a smooth, round angular torque distribution without peaks or singularities. Another source for measuring the actual power and / or torque value may be the electrical output of the generator.

The encoders may be absolute or relative encoders. To determine in a long term manner, absolute angle encoders may be used. Thereby, in the case of even a discontinuous monitoring or power failure, the offsets of the measured position values are constant with respect to each other. By analyzing the variations of the offsets of at least two absolute encoders located on different shafts, if torque computation and temperature effects are also measured and mathematically compensated, the variation in gearing within the system that is an indication of wear can be evaluated .

By determining absolute angular positions for the box fundament, further scenarios can be covered, using absolute encoders or encoders with precise reference marks at least once. For example, the first rotation of the gears measures the angle profile reference as a reference sensor, in particular in a loaded and unloaded and in both rotational directions. The reference sensor can then be used to determine wear or single effects. Also, in the case of making necessary repairs in the field, such as broken or heavily worn teeth that require the material to be applied (e.g., by welding, etc.), the reference sensor may be moved in a reference state (e.g. by special polishing of non- Can be used to re-establish. Therefore, a smooth angular position profile can be established without peaks that can indicate non optimal meshing of the gear wheels, particularly by reworking the affected sections of the cog wheel.

In addition to the above-mentioned modeling of a single shaft, the strength of the entire gearbox can also be calculated or experimentally evaluated, for example in running in phase. In theory, the experimental and actual system behavior can be compared, wherein the differences obtained indicate the conditions of the gearbox, and the information collected thereby can also be used to manage its life span.

In actual use, it is of interest, for example, not only structural sound or wear marks of the entire gearbox which can be detected only by the input and output encoders, but also where, at which stage or at what part of the gearbox wear problems arise. Many, all or at least most important system components or a smart array of sensors on their respective shafts can be used to precisely monitor the entire gearbox. Monitoring of the gear wheels can be done up to the monitoring level of a single tooth to determine the state of the teeth.

According to the invention, determining the shaft movement in a plurality of degrees of freedom, in particular in the further axial and eccentric directions, can obtain additional information on the state of the gearbox and more precise monitoring can be achieved.

On the other hand, this can be done by extending the system by combining angular encoders with other axial-sensor-means such as optical, capacitive or inductive displacement sensors.

Another approach is the use of an encoder configured to also determine eccentricities and axial shifts. The encoder may be implemented as a capacitive encoder, an optical rotary encoder, a magnetic encoder, or other type of encoder with the ability to measure angular position and at least one additional degree of freedom. For example, an optical angle encoder with a line sensor or an area sensor for the evaluation of an optical projection of any geometric 2D-pattern may be used, wherein the projected pattern may even be non-radial. Such sensors, evaluation circuits and evaluation software are optimized to determine changes in the position and / or scale of the projection. In the case of a radial disc including a 2D-pattern and an axial projection, the change of position represents the eccentricity, the change of scale represents the axial shift, and the pattern evaluation determines the angular position.

Known sensors of the prior art capable of detecting such effects are not conceived for the measurement of the effect itself, but rather are intended to achieve compensation for high precision angle measurements. The values of the axial and eccentric side effects are not even available in the outputs of sensors in the prior art because they are only used internally for angle measurement calibration purposes. Even when such information is available at separate outputs, it is not obvious to use the latter to monitor the different wear effects of the gearbox, since it is done in accordance with the present invention.

The basic principles for determining exemplary embodiments or additional degrees of freedom of the sensors can be found, for example, in WO 2008/083797, WO 2008/141817, WO 2007/051575 or EP 1 632 754.

Bearing failures and bearing wear can also be detected in accordance with the present invention because these problems are mainly manifested by eccentric or axial loosening. In particular, when helical cut gears are used, axial forces are present. In many cases, the bearings are pre-tensioned, and if they become loose over time, this can be an indication of wear. Particularly once the bearings are loosened, wear will increase. If not detected, this can lead to complete system failure, but if detected and re-stressed, this can be avoided and the overall lifetime can be increased without exchange and with less maintenance effort.

It is also possible to detect shaft-failures such as plastic deformations due to overloaded conditions, which may also result in eccentric or axial displacements. If the gearbox is kept in motion by such a deformed portion in the interior, aftereffects can occur, and therefore, not only the affected portion but also other portions will require maintenance or replacement.

Especially for gearboxes rotating at low speeds, wear monitoring by the encoders may be advantageous compared to wear monitoring by acoustic or vibration only, because many error terms to be determined are low due to low rotational speeds Frequency. Because acoustic and vibration analysis is advantageous for high frequencies, the combination of both wear monitoring principles covers a broad spectrum spectrum which is advantageous, especially if low speed and high speed rotations are to be covered.

In addition, precise monitoring of actual load-cycles improves the reliability of life estimation. For example, a gearbox that operates with lower loads far below its designed values will achieve extended service life. On the other hand, unexpected, harsh impacts can significantly reduce the remaining life below the expected value. The undetected, slight deformation of the inner portion due to the short time overload condition can lead to increased wear and can also affect other components of the gearbox. As a result, even a complete replacement of the entire gearbox will be required. By simple repairs of the direct deformation of the slight deformation, this can be avoided.

Another example that results in reduced life is an imbalance in one of the shafts. This can also be detected in accordance with the present invention because it is observable by eccentric influences, in particular by frequency or velocity dependent eccentrics.

The method, apparatus and setup according to the present invention will now be described or illustrated in more detail below, by way of example only, with reference to working examples schematically illustrated in the drawings.

Figure 1 shows an example of a first embodiment of a gearbox with a single stage for the description of the method according to the invention;
Figure 2 shows an example of a second embodiment of a gearbox with multiple stages and an alternative sensor setup according to the invention;
Figure 3a shows summarized gearings with exemplary embodiments of sensors that can be used in accordance with the present invention;
Figure 3b shows a simplified block diagram for illustrating the method according to the invention;
Figure 4 shows other examples of sensors that can be used by the special embodiment of the gearbox and the method according to the invention;
Figure 5 shows an oil-based stage of a gearbox to illustrate the applicability of the method according to the invention;
Figure 6 shows an embodiment of a windmill delivery system with sensors for the method according to the invention;
Figure 7 illustrates an example of a wind farm area monitored and managed in accordance with the present invention.

The diagrams of the figures should not be construed as being drawn to scale.

Fig. 1 shows an exemplary embodiment of a single-stage gear box 1 having two shafts, namely an input shaft 2A and an output shaft 2B. Obviously, the gear box 1 can also be used in the reverse direction to change the roles of the shafts 2A and 2B. The shafts 2A and 2B are supported by the bearings 10. The bearings 10 may be, for example, gliding bearings, roller bearings, air or fluid bearings, magnetic bearings, and the like. Since this embodiment represents a single stage gear box 1, there are two interaction gears 3A and 3B included in the gear box 1, namely, an input gear 3A and an output gear 3B . The gear box 1 can be applied with a forced lubrication system, which can be lubricated or filled with oil, in particular for friction reduction, or which can also include cooling purposes.

Gears 3A and 3B have different diameters and number of teeth to achieve the desired gear and transmission ratio because the conversion of the speed / momentum ratio is a common purpose of gearbox 1, but input shaft 2A ) Of the output shaft 2B with respect to the gear box 1 can be a purpose of the gear box 1. [

According to the present invention, there are at least two sensors 11A and 11B attached to the gear box 1. As described above, all the sensors can detect the angular position 30 of the shaft 2A with respect to the base 1 of the gearbox as the first degree of freedom. At least one of the sensors 11A, 11B or an additional sensor may detect axial displacement 31 or eccentric 32 displacement. In FIG. 1, the sensors 11A and 11B can detect three degrees of freedom, that is, the degree of freedom of rotation 30 around the axis, the degree of freedom of rotation in the axial direction 31, and the degree of freedom of the eccentricity 32. Skilled persons can see that the eccentricity (32) error itself can be interpreted as catatian displacement in two dimensions, resulting in a total of four dimensions of three linear and one rotation. Alternatively, eccentric 32 errors can be interpreted as polar displacements due to rotation angles and radii, and since only one additional degree of freedom in radial form is covered, as the rotational degrees of freedom are covered, Three rotation values and two linear values are generated.

For measurement of displacements due to wear, other influences such as temperature strain or mechanical strain can be removed mathematically by subtracting displacements resulting from measurement and modeling of cause effects such as temperature or torque and the resulting displacements.

The torque measurement can be made by measuring the torsion of the shaft by dedicated means according to the electrical output of the generator or by angle information from the sensors 2A and 2B. By angular measurement at the two ends of one (or more) torqued shaft sections, the difference in measurements will be proportional to the torque, in particular as a twist of the shaft, and in particular, one backlash and other influences are canceled out . By knowing the torque and rotational speed, which can be determined by angular encoders, the delivered power can also be calculated.

The angular displacements in the gearbox are good indicators for detecting the torsion of the gears and shafts and also for determining the backlash. Some backlash is inevitable for working gear transmission, but too much or too little torque is a disadvantage and an indication of an estimated reduction in service life. Further, complete failure or at least partial breakage of one or more teeth of the gearwheel is identifiable by increased backlash that occurs with a periodicity of rotation whenever the affected section of the gearwheel is interacting.

The actual forces and load conditions inside the gear box 1 are quite complex. For example, in general, the forces of a gear-gear combination transmit axial components that move the gears laterally (particularly with helical cut gears), radial components that move the two gear wheels away, Tangential components. Moreover, some frictional forces are also inevitable. These forces are all burdened to the gears 3A 3A, the bearings 10, the shafts 2A, 2B and the housing of the gear box 1 to achieve force balance.

The angular-only diagnosis of the prior art is not itself capable of detecting axial 31 and radial 32 influences. For example, due to the radial and tangential forces and the radii of the gear wheels- or axial forces result in bending moments exerted on the shafts and lateral and longitudinal forces in the bearings 10. The bending moments result in the eccentricity 32 of the shaft 2A compared to a theoretical force-free shaft axis. The lateral forces are also imposed on the bearings 10 in the axial direction 31 and displace the bearings 10.

The effects of these forces are also related to the state of the gearbox 1 and affect or indicate wear of the gearbox 1 and nevertheless they can not be detected and evaluated by rotary ON only encoders. A more accurate analysis of friction, strain, strain, losses and other influences is achieved by analyzing all forces or rather their effects in accordance with the present invention.

Bearings 10 can also be monitored in accordance with the present invention because they are also much more often worn than gear wheels 3A, 3B. In most cases, the bearing-wear does not result in increased clearance or backlash of the gear wheels 3A, 3B, but rather an eccentric or axial clearance which is not detected by the rotary only encoder.

The figure also shows the measured signals from the sensors 5A and 5B and the evaluation unit 4. To simultaneously determine the difference in angular position, the readings of the sensors 11A and 11B are preferably synchronized. The evaluation unit generates a signal indicative of wear of the gearbox 1 based on the position and displacement information sensed from the sensors 11A and 11B.

Fig. 2 shows a multiple stage gear box 1. The gearbox 1 comprises at least one input-shaft 2A to which a driving torque or momentum is applied, and at least one output-torque-torque-torque- And a shaft 2B. Between the two shafts 2A and 2B there is a plurality of gears 3A, 3B, 3C1 and 3C2 and in this particular example one is equipped with two gears 3C1 and 3C2 Stage-shaft 3C of FIG. Such multi-stage gearboxes can be viewed as a single stage of a daisy chain in which the input shaft of one stage is integrated with the output shaft of the previous stage and is not accessible from outside the gearbox, Resulting in an intermediate stage.

Gears are attached to the center shaft and are rotatable about the shaft by several bearings or are coupled to the shaft for transmission of torque from the gear to the shaft. There are also known special gear arrangements, such as sprockets, worm wheels, spur wheels, planetary wheel drives and the like, which can have more complicated mechanics than simple spur wheels.

There are also different shapes and arrangements of teeth known to the gears. For example, helical cut gears can achieve more running smoothness and produce less noise compared to orthogonally tooth-formed gears and have a side effect of additional axial forces on the shaft and bearings ≪ / RTI > In gears, teeth are an important part because they have to transmit torque from one wheel to another. Depending on the actual shape of the tooth and the precision of the shape, high punctual loads may occur on the face of the tooth. Moreover, some friction between the two interacting teeth will occur. Although friction can theoretically be avoided by design and can only be replaced by rolling motion, in fact, at least some friction always remains due to manufacturing errors, mounting inaccuracies, thermal expansion, and the like. Also, cyclical changes in the load profile of the teeth can cause fatigue problems and failures.

The load on the teeth of the gearbox 1 will lead to wear in the gearbox 1, which can cause damage to the gearbox 1. The total failure of both types of gearbox 1, i. E. Jamming or spinning, can also lead to serious follow-up injuries. Teeth-wear increases the friction and scuffing even further, especially if detected, and generates more heat, and even cracking, breaking loose or even breaking out of one or more teeth, Which may lead to subsequent tooth failure. In particular, in the event of a single tooth failure, the gearbox will continue to operate, but the load on the other teeth will increase thereby causing them to also fail within short time frames. The cleaved part of the teeth can also cause jamming if it is squeezed between the two gear wheels.

In particular, miscellaneous supplies, such as wind power plants, which require large forces to be transmitted, require corresponding large gears and gearboxes which are expensive and difficult to inspect and maintain. In addition, the entire machine has to pause for error diagnosis and maintenance, resulting in productivity losses.

Most torque-dependent measurements of the sensors can be accomplished by placing the sensor on the unloaded end of the shaft shown by sensors 11C and 11D. Since the gear wheels 3B and 3C2 themselves have a high torsional strength due to their geometry, the unloading ends of the shafts conform to the gearwheel substantially irrespective of the torsional effects due to the actual power transmitted by the gearbox, something to do.

The sensor 11D is an example of an embodiment using a dedicated linear position sensor, indicated by a bi-directional arrow in the sensor 11E, with axial freedom. The sensor 11A has a concomitant eccentric sensor 11F with two degrees of freedom shown next to the sensor 11F, which measures the same shaft as the sensor 11A. As mentioned, eccentricity can also be displayed in polar coordinates by angle and radius. Since the angular position has already been measured, only the radius has to be determined and this can be done, for example, by the radial distance sensing of the circumference of the shaft with an additional (linear) freedom of one.

In the embodiment shown, there is also sensor 11C in the inner-stage-shaft 2C. Thus, all the shafts in the gearbox 1 can be monitored and each gearing stage can be evaluated separately. This direct measurement is advantageous, for example, if the intermediate shaft 2C and / or its gear wheel 3C2 are known or expected to be the weakest link in the gearbox. In particular, the sensor 11C shown is even located inside the gear box 1.

In further embodiments, the other or more axes of the gearbox 1 may be equipped with sensors for a respective subset of degrees of freedom. For example, in a complete embodiment, each end of each shaft may be equipped with a sensor capable of sensing rotational, axial and eccentric degrees of freedom.

Fig. 3A shows a close-up of the gear system with two gear wheels 3A and 3B (teeth not shown) together with exemplary embodiments of the sensors for measurement above rotational degrees of freedom. The sensor 11A includes a code-wheel 111A and four sensors 112A arranged on the circumference of the code wheel. The arrangement of the sensors allows the determination of the eccentricity of the code wheel, and the sensors are embedded in such a way as to determine the axial position according to the scale factor for the projection of the code wheel (code wheel 'projection).

The sensor 11B includes a single line sensor 112B and a code wheel 111B holding a code for rotational positioning and also for evaluating the scaling and displacement of the projections of the rings to produce two inner sides for eccentric and also axial positioning Rings.

There are various other sensor designs that can measure rotational position and additional linear displacement or tilt. For example, European Patent Application No. 10157931.6 relates to the measurement of multiple degrees of freedom by a single device. In addition to these off-center sensing principles, as in DE 197 50 474, EP 1 890 113 or DE 39 24 460, which can be measured directly to the plane end of the shaft and also used according to the invention There are also known central sense encoders.

One single sensor for determining at least two degrees of freedom comprises code carriers 111A and 111B and sensor arrays 112A and 112B wherein the code carriers and sensor arrays are coupled to each other as a first degree of freedom about the axis of the shaft . The sensing includes detecting the occurrence of a code projection over the sensor arrays 112A, 112B and at least a portion of the code projection, depending on the three-dimensional displacement of the code carriers 11A, 111B relative to the sensor arrays 112A, 112B do. From the code projection, the angular position of the code carriers 111A, 11B is determined based on the axis of the shaft.

Also, a displacement value for at least one additional degree of freedom of the code carriers 111A, 111B for the sensor arrays 112A, 112B is determined based on the code projection, and in particular here the axial displacement of the sensor array relative to the code carrier And / or the eccentricity of the sensor array relative to the code carrier.

3B is a block diagram of a method of monitoring a gearbox 1 comprising a plurality of stages 45A, 45B, 45C with at least one corresponding shaft 2A, 2B, . The stages 45A, 45B and 46C are equipped with sensor means which may be of different types. As possible examples, the angular transducers 40A and 40B, the axial shift sensor 41A, the eccentric sensor 42B and the combined angle, axial and eccentric sensor 43C are described. The calculation unit 4 for monitoring the gearbox 1 receives a status signal 47 from the sensor data, which may contain single information or information dedicated to a particular component, stage or subset of the gearbox 1 .

As mentioned above, the acoustic / vibration analysis can cover the high frequency ranges fairly well, thereby allowing a combination of both wear monitoring principles to be used to cover a wide spectral range. In particular, if low speed and high speed rotations are present, a combination of position and sound monitoring may be advantageous. For example, in an embodiment in accordance with the present invention for a windmill or aberration gearbox, an input stage that rotates slowly to about 10 RPM may be monitored by angle sensing 45A, 45B, 45C, May be covered by acoustic and / or vibration monitoring 48 as an additional or alternative to position sensing. According to the present invention, also low frequency wear effects can be monitored, which can not be covered well by acoustic analysis, or are often overlapped by external noise and vibration sources, such as oscillating the entire Windmill Tower.

Fig. 4 shows a special embodiment of a worm gear, in which the shaft 2A is loaded in particular in the axial direction due to the design of the tooth system 3A.

The sensor 7A on the input shaft 2A and the corresponding code-section 8A are implemented as codes on the shaft 8A. The code 8A may be engraved, etched, printed, glued, for example on a shaft (laser), and the read head 7A may sense at least a portion of the code 8A Lt; / RTI > By sensing the distance between the shaft and the sensor, the eccentricity can also be determined, for example, optically or capacitively. The code 8A and the read head 7A can further determine the position in the axial direction in which the information is also to be assessed and determine the wear of the bearings which must withstand the axial load as well as the gearing. Such a system can also be used for rapid retrofitting since the shaft must only be stopped to apply the cord 9A.

In this embodiment, the second sensor 11B is configured as a tooth sensor that directly senses the teeth of the toothed wheel 3B. For example, this can be done capacitively or magnetically by estimating the distance between the sensor and the teeth. The rotating cogwheel will produce a signal having an alternating part representing, for example, teeth and angular position and offset that may have a periodicity of one revolution due to eccentricity. Obviously, the above-mentioned sensor principles are not limited to worm gears but can be applied to other gearbox types as well.

5 shows an embodiment of a planetary gear stage. In one embodiment, the planet gears have a rotating outer ring 3A and a standstill planet carrier 50 to which the planetary wheels 3C, 3D, 3E are attached. Another embodiment is realized by the fixed outer ring 3A and the rotating planetary carrier 50. The arrangement of the sensors varies accordingly, because rotating sensors connected rotatably or by radio means can be used differently, but the arrangement of sensors on non-rotating components .

In the illustrated example, the planet carrier 50 is static and therefore the planetary wheels 3C, 3D, 3E can be sensed by the three sensors 11C, 11D, and 11E. In addition, the input-and-output-shafts or wheels 3A and 3B may be sensed by sensors 11A and 11B. Therefore, although the planet gears are known to be difficult to monitor by acoustic means, the entire gear can be monitored.

When the planet carrier is rotating, the sensing of the planet wheels may require a rotatable electrical connection or some radio means, but at least the rotation of the entire carrier can be sensed, which can cause the planetary carrier to suffer from eccentricity will be.

6 shows another embodiment of a mechanical transmission system of a wind power plant having a rotor 20, a gear box 1 and a generator 21. [ The gearbox 1 comprises a number of, in particular three stages, the first stage of which is an oil-based stage 22 and the remainder comprises helical-cut gear wheel stages 23, 24. According to the invention, the shafts of the axis are equipped with sensors 11A to 11G, and at least one of the sensors is preferably all rotatable and at least one additional degree of freedom, in particular an axial and / Can be detected.

7 shows a schematic view of a wind power plant area having a plurality of wind mills 99 each having a rotor 20 connected to a gear box 1. On the other end of the gear box 1, there is an electric generator 21. All these parts are inside the nacelle 100 on the tower 101. The gear box 1 is equipped with a monitoring device 4 according to the invention for monitoring wear of gearboxes and life management.

The monitoring device 4 allows precise monitoring or wear conditions of each windmill 99. Not only the health of the entire wind mill 99 can be determined, but also the diagnosis can be performed up to a particularly important component level by the obtained sensor. One example of an advantage of the present invention is that by knowing the spare parts that are needed even before opening the gearbox, the necessary parts can be obtained prior to maintenance. In addition, statistical analysis such as a failure trend can be made at a very precise level.

Not only can a maintenance plan be planned based on these sensors, but also a plan of additional load distributions between windmills in a wind farm can be planned to achieve equalization of service periods between multiple windmills , Allowing multiple windmills to remain at random on the current demand in the same time frame.

Since the reduction in load on half-worn gearboxes can extend its life span to some extent, maintenance can be scheduled in a desired time frame, for example in a calm season according to a weather forecast, (Although with slightly reduced efficiency) still produce energy.

Claims (15)

A method of monitoring wear of a gearbox (1) in a power plant (99), said gearbox comprising at least the following components:
At least the first shaft 2A,
At least the second shaft 2B,
Gears (3A, 3B) and
- Bearings (10)
The method
- sensing a first angular position (40A) of said first shaft (2A) by means of a first rotary shaft encoder,
Sensing a second angular position (40B) of the second shaft (2B) by a second rotary shaft encoder,
- monitoring said wear of said gear box (1) according to differences of said sensed angular positions of said first shaft (2A) and second shaft (2B), and
- generating a condition-signal (47) indicative of said wear of said gearbox (1) in accordance with said monitored differences, characterized in that it comprises the steps of: ,
Includes the additional detection of displacement of the first shaft (2A) or the second shaft (2B) with at least one additional degree of freedom (41A, 42B, 43C)
Characterized in that said displacement in said further degrees of freedom is included in the generation of said monitoring and said state-signal as an indication of wear. The method according to claim 1,
Characterized in that said sensing of said angular position and said displacement in one of said shafts is carried out by one single means of sensing at least two degrees of freedom. 3. The method of claim 2,
Said one single means comprising:
A code carrier and a sensor array are rotatable relative to each other as a first degree of freedom,
Wherein the sensing comprises:
On said sensor arrangement (112A, 112B), said code projection is generated on the basis of the three-dimensional displacement of said code carrier (11A, 111B) relative to said sensor arrangement (112A, 112B) Detecting a portion,
- determining said angular position of said code carrier (111A, 11B) from said code projection,
- determining a displacement value for said at least one further degree of freedom of said code carrier (111A, 111B) for said sensor arrangement (112A, 112B) based on said code projection A method of monitoring wear of a box (1). 4. The method according to any one of claims 1 to 3,
At least two angular positions at different axial positions on each of the first shaft 2A, the second shaft 2B and the intermediate shaft 2C are sensed and the respective shafts 2A, 2B, 2C Characterized in that a twist of the gear box (1) is determined. 5. The method of claim 4,
Characterized in that the efficiency or losses of the gearbox (1) are determined according to the sensed positions or displacements and the determined torque load. 4. The method according to any one of claims 1 to 3,
Characterized in that said condition of said bearings (10) is monitored in accordance with the sensed axial or eccentric displacement of the shafts (2A, 2B, 2C). 4. The method according to any one of claims 1 to 3,
Characterized in that each of the shafts (2A, 2B, 2C) in the gear box (1) is sensed for their actual position or orientation in at least two degrees of freedom . 4. The method according to any one of claims 1 to 3,
Characterized in that it comprises additional acoustic / vibration monitoring of the gearbox (1). 4. The method according to any one of claims 1 to 3,
(47) of the gearbox (1), characterized in that it comprises the management of the life of the gearbox (1) according to the state-signal (47). As a gearbox monitoring device for power plants,
· Angular shaft encoder for first-shaft (2A)
An angle shaft encoder for the second-shaft 2B and
- a gearbox monitoring device comprising a calculation unit (4) for monitoring the wear-state of the gearbox (1) in accordance with the signals of the angle shaft encoders,
And at least one displacement sensor for determining displacements of the shaft of the gearbox (1) in at least one translational degree of freedom, the calculation unit comprising: Is configured in such a way as to determine the wear of the gearbox (1) in accordance with at least one signal from at least one displacement sensor. 11. The method of claim 10,
Wherein the angular shaft encoder and the displacement sensor are implemented as a single sensor configured in a manner that senses at least two degrees of freedom. The method according to claim 10 or 11,
Characterized in that the first or second shaft has an additional angle shaft encoder and the tweight of the shaft is determined by the calculation unit (4) according to the difference in the relative angular position of the angle shaft encoders Monitoring device. The method according to claim 10 or 11,
Characterized in that a sensor is equipped on the intermediate-stage-shaft (2C) of the gear box (1). In a wear monitoring gearbox system,
A wear monitoring gearbox system comprising a gearbox (1) and a gearbox monitoring device according to claims 10 or 11, for use in the practice of the method according to any one of claims 1 to 3. 13. A machine-readable medium having stored thereon a program code, the program code being programmed to cause the computer to perform any of the steps of any one of claims 1 to 3 when the program code is executed on a calculation unit of a gearbox monitoring apparatus according to claim 10 or 11. To automatically execute and operate a method of monitoring the wear of a gearbox according to claim < RTI ID = 0.0 > 1, < / RTI >

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