EP2203730A2

EP2203730A2 - Measuring device for detecting the operating state of a shaft, method and shaft arrangement comprising said measuring device

Info

Publication number: EP2203730A2
Application number: EP08839450A
Authority: EP
Inventors: Tobias Hagemann; Christian Schaaf
Original assignee: Schaeffler Technologies AG and Co KG
Current assignee: Schaeffler Technologies AG and Co KG
Priority date: 2007-10-17
Filing date: 2008-10-16
Publication date: 2010-07-07
Also published as: US20100282002A1; DE102007049672A1; WO2009049610A2; WO2009049610A3

Abstract

The aim of the invention is to provide a measuring device, a method, and a shaft arrangement comprising said measuring device, which enable a robust and simultaneouly precise measurement of the torque, a torque variation and/or an equivalent variable. To this end, the invention provides a measuring device for detecting the torque operating state of a shaft (3), in the form of a torque, a torque variation and/or an equivalent variable, said device comprising a signal emitter (5) that can be connected and/or is connected to the shaft in a rotationally fixed manner, a signal receiver (7) designed to detect signals from the signal emitter and emit a measuring signal having a constituent dependent on rotational speed, according to the detection of the signals of the signal emitter. The measuring device also comprises an evaluation device (8) for determining the torque operating state of the shaft (3) on the basis of, and/or, by evaluation of the measuring signal. The evaluation device (8) is designed to carry out and/or complete the determination of the torque operating state by analysing signal constituents of the measuring signal, that have a limiting frequency which is higher than the current rotational frequency of the shaft.

Description

Name of the invention

Measuring device for detecting the operating state of a shaft, method and shaft arrangement with the measuring device

description

Field of the invention

The invention relates to a measuring device for detecting the torque operating state of a shaft in the form of a torque, a torque change and / or an equivalent size with a signal generator which is rotatably connected to the shaft and / or connected to a signal receiver, which for detection is formed of the signal generator and outputs a measurement signal with a speed-dependent component as a function of the detection of the signal generator, and with an evaluation device for determining the torque operating state of the shaft based on and / or by evaluation of the measurement signal. The invention further relates to a corresponding method for detecting a torque operating state of a shaft and a shaft arrangement with the measuring device. The measurement of a torque or a torque change of a shaft during operation is often part of a monitoring of a manufacturing or working machine. The knowledge of the torque is necessary to z. For example, it is possible to make estimates about work quality, load or wear of the respective machines.

The metrological determination of the torque is often carried out with a serially coupled intermediate member whose torsion is measured and converted over predetermined characteristics into a torque. For example, optical measuring methods are used, in which the displacement of two spaced apart from each other at an axial distance reference marks in the circumferential direction is detected metrologically. Other measuring systems evaluate the torsion of the intermediate member with mechanical or magnetic measuring means. However, the intermediate elements necessary for the measuring methods limit the applicability of this type of measuring method to shafts which transmit only small torques.

In another type of torque measurement, the distortion of the torque-loaded shaft is measured directly on the basis of different measuring methods. In these measuring methods, the shaft is provided, for example with strain gauges (DMS), which detect the distortion. Methods are also known in which the change in a magnetic field is measured due to twisting of the shaft and a torque is derived therefrom. These methods evaluate path differences in a sub-millimeter range due to the twist and are therefore susceptible to interference due to the system in difficult operating environments such as soiling, heat and the like. Common practice is to use the electric current of the drive motor of the shaft as a basis for calculating an estimate of a torque actually transmitted through the shaft. In this case, the motor current or the motor power is offset with a speed of the shaft tapped off at any desired position, and from this a torque is estimated. In the article "Measure directly on the shaft" by Lutz May, published in "Computer &Automation" 8/05, page 73 et seq., The latter solution is evaluated disadvantageously, as these too slow reaction times, inaccurate measurements and a constantly changing reference base should show. As a solution, it is proposed in the article, instead of determining the torque over the motor current, to apply a magnetic coding on the shaft and to determine the torque over the magnetic field changing due to the stress or distortion irrespective of the rotational speed or direction of rotation of the shaft.

The invention has for its object to provide a measuring device, a method and a shaft assembly with the measuring device, which allow a robust yet accurate detection of torque, a torque change and / or an equivalent size.

This object is achieved by a measuring device having the features of claim 1, by a method having the features of claim 11 and by a shaft arrangement having the features of claim 13. Preferred or advantageous embodiments of the invention will become apparent from the dependent claims, the following description and the accompanying drawings.

According to the invention, a measuring device is proposed for detecting a torque operating state of a shaft, wherein the torque operating state describes the torque transmitted via the shaft, or its change and / or a variable equivalent thereto. The measuring device comprises a signal generator, which is rotatably connected to the shaft and / or connected, wherein the signal generator rotates during operation of the shaft with this. On the one hand, the signal generator can be a separate component, which is fastened on or on the shaft in any desired manner. Alternatively, the signal generator is realized as an integral and / or integral with the shaft component. The signal generator can be designed in the most general definition for the output and / or change of any signal, in particular a magnetic, optical, electrical, electromagnetic, capacitive and / or inductive signal.

The measuring device further comprises a signal receiver, which is designed to detect the signal generator. The signal receiver can be realized as a passive signal receiver, wherein a signal actively output by the signal generator is detected or as an active signal receiver, wherein the signal receiver sends a test signal to the signal generator, this modifies the test signal and the signal receiver then receives the modified test signal.

In terms of programming technology and / or circuitry, the signal receiver is designed in such a way that, depending on the detection of the signal generator, a measurement signal is output with a component which is dependent on the rotational speed of the shaft.

Furthermore, the measuring device shows an evaluation device which determines the torque operating state of the shaft on the basis of or by evaluation of the measurement signal.

Following the invention, it is proposed that the evaluation orientation is designed in terms of programming and / or circuitry so that the determination of the torque operating state is carried out and / or supplemented by analyzing signal components of the measuring signal with a cut-off frequency greater than the current rotational frequency.

In contrast to the known prior art, not only the rotational frequency of the shaft is used as a slowly changing variable for determining the torque operating state, but the high-frequency components of the measurement signal for highly dynamic determination of the torque operating state of the shaft used. Preferably, the measurement signal is evaluated in such a way that the rotational speed and at least one further characteristic variable are determined from the measurement signal, wherein the further parameter is used to determine the torque operating state. The parameter is designed in particular as a time-dependent information signal, wherein the information-carrying components of the information signal are located in a frequency range greater than the cutoff frequency.

Optionally, the determination of the torque operating state is performed using a high-pass filtered measurement signal having a cut-off frequency greater than the current rotational frequency and / or the maximum rotational frequency of the shaft.

The measuring signal is preferably designed as a local and / or angular time signal, which provides a time-dependent location and / or angle information of the shaft. Alternatively or additionally, the measurement signal can also be realized as a speed and / or acceleration signal.

A consideration of the invention is that precisely high-frequency torque changes can be detected by a change in the synchronous operation of the shaft, as long as the synchronization of the shaft is recorded sufficiently accurately by measurement. In turn, it is possible from the deviations of the synchronism of the shaft conclusions on the current torque and / or to draw an actual torque change and / or to an equivalent size to this. The measuring device thus has the advantage of being able to measure the torque or the torque change of a shaft with high precision with a comparatively simple and therefore robust measuring structure.

In a preferred embodiment of the invention, the cutoff frequency is a multiple, preferably at least a tenfold, in particular a hundredfold, in particular a thousand times the rotational frequency and / or the maximum rotational frequency of the shaft. These high-frequency signal components of the measurement signal carry the information about the instantaneous torque or about the instantaneous torque change.

In a preferred development of the invention, the torque operating state of the shaft is determined using a further auxiliary variable, the further auxiliary variable being dependent on the current torque of the shaft. A particularly preferred alternative for the auxiliary size is a variable proportional to the current and / or to the power and / or to the voltage of a motor driving the shaft and / or of a generator driven by the shaft. In the event that the shaft driving unit is not designed as an electric motor, but for example as an internal combustion engine, for example, a speed, consumption or the like of the engine is used to form the further auxiliary size.

In a preferred constructional realization of the signal generator, the latter has a plurality of coding features which can be distributed and / or distributed around the shaft in the direction of rotation. Preferably, more than 100 coding features are mounted on a shaft. In principle, the coding features in the direction of rotation with different distances from each other and / or each be designed differently. In a preferred embodiment, which facilitates the evaluation of the measurement signal, however, the coding features are each of the same design and / or arranged equidistantly in the direction of rotation. Particularly preferably, the coding features are arranged in a common radial plane perpendicular to the axis of rotation of the shaft, so that they each also have the same axial position.

In a particularly robust and therefore preferred embodiment of the invention, the signal generator or the coding features on a magnetic coding, which is detected by the signal receiver. Especially the magnetic coding is - for example compared to an optical see coding - even in harsh industrial environments very robust and prone to failure.

In particular, it is provided that signal transmitter and signal receiver are designed as an incremental encoder device, which provides at least 10, preferably at least 100, in particular at least 1000 signals per revolution of the shaft. On the one hand, it may be provided that the number of coding features corresponds to the number of signals. On the other hand, it is also possible to use a plurality or a multistage signal receiver which reads off a coding feature at different circulating positions of the shaft in a spatially offset manner. For example, in a wave with 100 coding features and 5 distributed signal receivers, a measuring signal is provided which comprises 500 signals per revolution.

Another object of the invention relates to a method for measuring a torque of a shaft having the features of claim 11, preferably using the measuring device described above. In the measuring method, a measuring signal is recorded with a speed-dependent component of the shaft and carried out by analyzing signal components of the measuring signal with a cut-off frequency greater than the current rotational frequency of the shaft, the determination of Drehmomentbetriebs- state and / or supplemented. Optionally, the determination of the torque operating condition is made using an auxiliary amount previously described.

Another object of the invention relates to a shaft arrangement, in particular in a rolling mill, for example for steel, in a printing unit, for example, for paper, in a wind turbine, for example, for the rotor, in a marine propulsion, for example, to drive the screw , with a drive shaft for driving a cylinder, generator, a screw or the like, wherein the drive shaft for the transmission of high power of more than 100 kW, in particular more than 1 MW and in particular more than 10 MW is formed and / or arranged , wherein the torque operating state with a measuring device as described above or is carried out with a corresponding measurement method.

In a preferred implementation of the shaft arrangement, the signal transmitter is arranged in or on a torque-loaded intermediate member. In particular, the implementation ensures that the signal generator is not positioned on a free, unloaded shaft end. In contrast, it is preferred that the signal transmitter is arranged on an intermediate member in the kinematic chain between the torque generator and the torque consumer. The torque generator is designed, for example, as a motor and the torque consumer as the rolls of the rolling mill or the printing unit. Preferably, the signal generator is mounted directly in front of the torque consumer, in particular on its input shaft. In alternative embodiments, the torque generator is powered by, for example, wind or hydro, or is designed as an internal combustion engine. The torque consumer is designed as a generator, propeller, etc. In these embodiments, too, it is preferred that the signal generator is positioned in the region of the torque consumer.

In summary, the advantages of preferred embodiments of the invention are in particular that can be determined by the use of a high-precision speed measurement and a significant increase in the signal sampling torque operating conditions with an accuracy that could previously only be achieved, for example, by gauging enbasierte systems. Thus, the invention is characterized by the advantages of a simple sensor technology, a simple application technique and a low economic outlay. Particularly preferably, the speed sensor is positioned in the region of the torque load and in particular is not arranged on the torque-free shaft end of the motor shaft. The invention makes use of the fact that damping effects determined by the measuring method, which result from the mechanics, are determined with the aid of analytical methods, such as transfer functions, state controllers, neural networks, fuzzy logic, etc., and implemented in the calculation of the torque.

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

Figure 1 is a highly schematic block diagram of a measuring device for determining a torque operating state as a first embodiment of the invention; FIG. 2 shows a highly schematic representation of the signal generator

Receiver area in Figure 1.

1 shows in a highly schematic block diagram a shaft arrangement 1, which comprises a torque generator 2, such as an electric motor or combustion engine, at least one torque transmitting drive shaft 3 and a torque consumer 4, wherein a torque from the torque generator 2 via the drive shaft 3rd is transmitted to the torque consumer 4. The torque consumer is designed, for example, as a rolling mill, pressure roll of a printing press, generator or the like.

In a torque-loaded area, a signal transmitter 5 is arranged on the drive shaft 3, which distributes a multiplicity of coding features 6 in the circumferential direction. The coding features 6 are preferably designed as magnetic codings, the number of which in this embodiment preferably being more than 2000.

For detecting the coding features 6 of the signal generator 5, a signal receiver 7 is set up, which scans the coding features 6 without contact. The signal receiver 7 generates a measurement signal from the scanning signals, which thus provides a time-dependent signal.

The measurement signal is transmitted to an evaluation device 8, which determines based on the high-frequency components, in particular components with frequencies greater than the rotational frequency of the drive shaft 3, a torque and / or a torque change in the transmission of the drive shaft 3. Optionally, 2 power signals are transmitted as an auxiliary variable of the torque generator, which can be formed, for example, in an electric motor as current and / or voltage signals and in an internal combustion engine as speed or consumption.

A possible alternative embodiment is to detect slowly changing components of the torque via the change in the performance data of the torque generator 2 and to determine faster changes in the torque via the evaluation of the high-frequency measurement signal. To determine the rapid changes, for example, the time intervals of two successive increments, the shape or the edge steepness of the individual pulses of the increments are evaluated.

FIG. 2 shows in a highly schematized manner a possible embodiment of the transmitter-receiver region in the shaft arrangement in FIG. 1. The coding features 6 are designed as magnetic codings in strip form with axial alignment. To ensure trouble-free detection of the coding features by the signal receiver, the strips are spaced in the circumferential direction at a distance of 5 mm to 10 mm. In order nevertheless to obtain a sufficiently high number of signals per revolution, a plurality of signal receivers 7 are arranged in the direction of rotation and axially offset from one another, so that each coding feature 6 is read several times per revolution, in this example four times.

LIST OF REFERENCE NUMBERS

1 shaft arrangement

2 torque generator 3 drive shaft

4 torque consumers

5 signalers

6 coding feature

7 signal receiver 8 evaluation device

Claims

claims

A measuring device for detecting the torque operating state of a shaft (3) in the form of a torque, a torque change and / or an equivalent size

with a signal generator (5) which is rotatably connected to the shaft (3) and / or connected,

with a signal receiver (7), which is designed to detect the signal generator and outputs a measuring signal with a speed-dependent component as a function of the detection of the signal generator,

and with an evaluation device (8) for determining the torque operating state of the shaft (3) on the basis of and / or by evaluating the measurement signal,

characterized,

in that the evaluation device (8) is designed to carry out and / or supplement the determination of the torque operating state by analyzing signal components of the measuring signal with a cut-off frequency greater than the current rotational frequency of the shaft.

2. Measuring device according to one of the preceding claims, characterized in that the cutoff frequency is a multiple, preferably at least a 10-fold, in particular at least a 100-fold and in particular at least a 1000 times the orbital frequency.

3. Measuring device according to claim 1 or 2, characterized in that the evaluation device (8) is designed to determine the operating state using a further auxiliary variable, wherein the further auxiliary variable is dependent on the current torque of the shaft (3).

4. Measuring device according to claim 3, characterized in that the further auxiliary variable as a to the current of the shaft driving the motor (2) and / or driven by the shaft generator

(4) is proportionally sized.

5. Measuring device according to one of the preceding claims, characterized in that the signal generator (5) has a plurality of coding features (6) which are distributed in the direction of rotation about the shaft (3) and / or distributed.

6. Measuring device according to claim 5, characterized in that the coding features (6) have the same design and / or are arranged equidistantly to one another in the direction of rotation.

7. Measuring device according to one of claims 5 or 6, characterized in that the coding features (6) in a common radial plane perpendicular to the axis of rotation of the shaft (3) are arranged.

8. Measuring device according to one of the preceding claims, characterized in that the signal transmitter (5) has a magnetic coding, which is detected by the signal receiver (7).

9. Measuring device according to one of the preceding claims, characterized in that the signal generator (5) and signal receiver (7) are designed as incremental encoder device.

10. Measuring device according to claim 9, characterized in that the encoder device provides at least 10, preferably at least 100, in particular at least 1000 signals per revolution.

11. A method for detecting a torque operating state of a shaft (3) in the form of a torque, a torque change and / or an equivalent size, wherein by a measuring device preferably according to one of the preceding claims, a measurement signal with a speed-dependent component of the shaft (3) recorded and A determination of the torque operating state is performed and / or supplemented by analyzing signal components of the measurement signal with a cutoff frequency greater than the current rotational frequency of the shaft (3).

12. The method according to claim 11, characterized in that the torque operating state of the shaft (3) takes place using the speed-dependent component and a further auxiliary variable, wherein the auxiliary variable is preferably designed as a motor torque of the shaft driving motor of certain torque value.

13. shaft assembly (1), in particular rolling mill, printing unit, wind turbine, marine propulsion, etc., with a drive shaft (3) for driving a cylinder, generator, screw, a roller or the like, wherein the drive shaft for the transmission of high power of more is formed as 100 kW, preferably more than 1 MW, in particular more than 10 MW, characterized in that a torque operating state of the drive shaft (3) with a measuring device according to one of claims 1 to 10 and / or by means of a method having the features 11 to 12 is determined.

14. Shaft arrangement (1) according to claim 13, characterized in that the signal transmitter is arranged in or on a torque-loaded intermediate member (3).

15. shaft assembly (1) according to claim 14, characterized in that the signal transmitter (5) on one or the intermediate member in the kinematic chain between the torque generator (2) and torque consumers (4) is arranged.