GB2586583A

GB2586583A - Rotating machine

Info

Publication number: GB2586583A
Application number: GB1911533.6A
Authority: GB
Inventors: Jacobs-Cook Alan; Pinnock Robert
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2019-08-12
Filing date: 2019-08-12
Publication date: 2021-03-03
Anticipated expiration: 2039-08-12
Also published as: GB201911533D0; GB2586583B

Abstract

A rotating machine 100 comprising: a casing 102; and a vibration sensor 106 configured to provide an output indicative of a condition of the rotating machine; wherein the vibration sensor includes a 2D material film, the 2D material film being attached to a surface 112 of the casing. The 2d material film may include graphene. The condition may include a wear condition, break or fracture of a component and/or failure or predicted failure of the rotating machine.

Description

ROTATING MACHINE

The present invention relates to a rotating machine comprising a casing and a vibration sensor. Particularly, but not exclusively, the rotating machine may comprise an electric motor. The invention also relates to a method of monitoring a condition of a rotating machine using an output of a vibration sensor.

It is desirable to be able to monitor rotating machinery in a way that allows condition monitoring, diagnostics, and prognostics of the machinery. The monitoring can enable the detection of a variety of wear and failure mechanisms and predict lifetime to failure of the rotating machine. One favoured method of monitoring rotating machines is the provision of acoustic or vibrational sensing.

Commonly, such sensing relics of arrays of microphones positioned around the rotating machine to he monitored. Sophisticated signal monitoring is then required to interpret the received signals into information useful to indicate the status of the machine. This method of monitoring is bulky and expensive, and is therefore inadequate for long-term performance monitoring of a rotating machine. Instead, such set-ups are used either for one-off applications or to investigate a known problem in a particular piece of machinery.

When seeking to identify fault features in the rotating machinery, the performance of acoustic monitoring systems is dependent critically on the placement of the array of microphones. This therefore requires specialist knowledge in order to achieve the desired result.

Moreover, where microphones are positioned at a distance from the rotating machinery to be monitored, they necessarily detect the "far-field" acoustic signature of the machinery. Acoustic signals relating to or indicative of specific faults or wear mechanisms, however, tend to be detectable in the "near-field" acoustic signature and difficult or impossible to detect in the "far-field". In some cases, it may be possible to adapt a "far-field" signature to reverse-engineer the "near-field" signature that produced it, but this is far from simple to achieve.

Other methods of monitoring rotating machines rely on vibrational monitoring by the application of accelerometers to the machinery itself. Whilst in principle these techniques can he used to detect specific faults, they are also subject to shortcomings.

For example, the size of accelerometers precludes the attachment of significant numbers of sensors. Their size may also be an issue where the arrangement of the rotating machine and/or its surrounding components means that it is not possible to access specific parts of the machine for monitoring. Moreover, as only a small number of accelerometers can be attached, the position of their attachment is critical to providing useful output signals. If these positions are incorrect, fault conditions may be missed.

In addition, particular types of accelerometer have limited dynamic range. If the frequencies that are indicative of specific faults fall outside of this limited dynamic range, the acoustic signatures may he missed.

According to a first aspect, there is provided a rotating machine comprising: a casing; and a vibration sensor configured to provide an output indicative of a condition of the rotating machine; wherein the vibration sensor includes a 2D material film, the 2D material film being attached to a surface of the casing.

Providing acoustic or vibration sensing enables monitoring of the condition of the rotating machine without requiring sensors internal to its casing. Such monitoring can detect acoustic or vibrational signatures of such things as wear, fracture, breakage, or other failure as well as provide signals indicative of a predicted failure or a remaining lifetime before failure.

By providing a vibration sensor including a 2D material film, a sensing can be achieved in spaces that would normally be difficult or impossible to provide vibrational or other forms of sensing. For example, rotating machines may be present in cramped or restricted spacing in which the use of conventional sensors may not be achievable or may be impractical.

The 2D material film may be at least one of a piezoelectric 2D material film and a strain-sensitive 2D material film.

Such material films may provide easily readable outputs in response to the propagation of vibrations through the casing. Such materials may include 2-D materials such as boron nitride and molybdenum-and tungsten-based compounds.

Discussion of various suitable materials can be found in the following paper: K. Duerloo, Y. Li, M. Ong and E. Reed: "Intrinsic Piezoelectricity in Two-Dimensional Materials"; J. Pin's. Chem. Lett., 3, 19 (2012).

The 2D material film may be provided in a plurality of positions on the surface of the casing. A plurality of readings may therefore he provided by the vibration sensor.

Each reading may he provided from each of the plurality of positions.

The plurality of positions may provide a plurality of sensor reading corresponding to spaced points on the surface of the casing. In such an arrangement, the vibration sensor may provide readings specific to points of interest, which may he provided on different, spaced-apart, areas of the casing.

The plurality of positions may provide an array of sensor readings over a portion of the surface of the case.

The plurality of positions may be arranged in a grid formation. A grid formation may allow monitoring of a large portion of the casing.

The plurality of positions may be arranged in a pseudorandom formation. Such pseudorandom formations may ensure that regular nodes or antinodes in a sensed vibration pattern are not inadvertently missed. For example, where detectors are arranged in a regular pattern they may all be at or close to the regular antinodes of a standing-wave type vibrational pattern, limiting effectiveness. By using non-regular or pseudorandom detector patterns, usch possibilities can be prevented.

The vibration sensor may he configured to provide continuous and/or long-term condition monitoring of the rotating machine.

The vibration sensor may be configured to provide fault condition diagnostics of the rotating machine.

The output of the vibration sensor may be indicative of a wear condition, break or fracture of a component, and/or failure or predicted failure of the rotating machine.

The rotating machine may further comprise a processor that is configured to receive the output from the vibration sensor and determine the condition of the rotating machine.

The rotating machine may comprise an electric motor.

According to a second aspect, there is provided a method of monitoring a condition of a rotating machine, the method including the steps of: providing a vibration sensor comprising a 2D material film that is attached to a surface of a casing of the rotating machine; and monitoring an output of the vibration sensor, the output being indicative of the condition of the rotating machine.

The method may further comprise the step of determining from the output of the vibration sensor whether the rotating machine has a fault or is likely to develop a fault.

The fault may include one or more of a wear condition, break or fracture of a component, and/or failure or predicted failure of the rotating machine The rotating machine and vibration sensor may include any of the preferable or optional features described in relation to the first aspect.

Specific embodiments will now be discussed in detail with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of a rotating machine according to the first aspect; Figure 2 is a schematic arrangement of a first example of a vibration sensor on a casing; Figure 3 is a schematic arrangement of a second example of a vibration sensor on a casing; Figure 4 is a schematic arrangement of a third example of a vibration sensor on a casing; and Figure 5 is a flow diagram of the method according to the second aspect.

Referring firstly to Figure 1, there is provided a rotating machine 100. The rotating machine 1 00 is in the form of an electric motor, although the disclosure is also applicable to any other form of rotating machine. The rotating machine 100 includes a casing 102, which in the depicted embodiment encloses the inner components (not shown) of the rotating machine 100. An output shaft 104 is shown that allows the output of the rotating machine 100 to be transmitted to other parts of an assembly (not shown).

A vibration sensor 106 is attached to the casing 102 of the rotating machine 100, the vibration sensor 106 being configured to provide an output indicative of a condition of the rotating machine 100. By "a condition", it is meant the presence or absence of a fault, such as, for example, a vibrational or acoustic signature of a crack, fracture, break, misalignment, imbalance, or other feature of one or more component of the rotating machine 100. Where the rotating machine is a motor the components may include a stator and rotor of the motor. Where the rotating machine is a gearbox, the components may include one or more shafts or gears of the rotating machine.

An output signal of the vibration sensor 106 is provided to a processor 108, which is configured to process the output signal in order to determine the condition of the rotating machine 100. An output of the processor 108, which is indicative of the condition, can then be provided to a monitoring device 110, or any other part of a system that may benefit from the information provided by the processor 108.

The vibration sensor 106 includes a 2D material film that is attached to a surface 112 of the casing 102. The 2D material film may be of any kind that is capable of providing an output signal to the processor 108 that is indicative of a vibration of the casing 102. For example, the 2D material film may he a piezoelectric material or may be a strain-sensitive material. Such materials may include 2-D materials such as boron nitride and molybdenum-and tungsten-based compounds. Discussion of various suitable materials can be found in the following paper: K M Or 3nt: r.1 z An output signal of the vibration sensor 106 may therefore he provided by monitoring of a voltage, resistance, current, or other characteristic of the 2D material film. The vibration sensor 106 may therefore be active or passive, i.e. the characteristic of the 2D material film may be monitored actively, for example by applying a voltage and monitoring the current flowing through the vibration sensor 106, or may be monitored passively by monitoring for a voltage change across the vibration sensor 106. Other such characteristics that are applicable to the present application, and methods of monitoring said characteristics, will be known to the skilled person, and may be dependent on the 2D material film selected.

Although the vibration sensor 106 may be provided as a single area of 2D material film, suitable for providing a single output signal, it may be preferable to provide multiple areas of 2D material film, the vibration sensor 106 therefore being able to provide multiple output signals to the processor. Three examples of arrangements of the 2D material film are shown in Figures 3 to 5. In each case, the processor and any detail of the rotating machine is omitted.

A first arrangement is shown in Figure 3. In this first arrangement, the 2D material film is provided in four positions or sensing areas 214. Each sensing area 214 is positioned on a part of the surface 212 of the casing 202 where vibration monitoring is desired. These areas of interest may correspond to positions in which vibrations from specific internal components of the rotating machine 200 may be monitored, for example.

The positioning of each sensing area may depend on the type of machine and the type of condition being monitored. In the case of a gearbox, it may be desirable to appropriately place the sensor areas to be able to determine (a) that a gear tooth is or is not damaged and (b) exactly where the damage is. Alternatively, it may be possible to identify incipient problems from subtle changes in vibrational patterns across a whole area of the machine rather than a more specific location. In this latter case, the vibrational pattern may still offer information as to the location of the problem, indicated by the changes in the vibrational pattern.

As the sensor areas will detect near-field vibrational patterns rather than the far-field patterns detected by more conventional techniques, the location of the cause of the vibrational change will be more easily detectable. Moreover, detection in the near-field prevents or limits the chances of any problems being masked by general mixing of signals in the far-field region.

In the depicted embodiment, each sensing area 214 is of equal size, but this need not necessarily be the case and a range of sizes of sensing area may be provided, depending on individual requirements. The sensing areas in combination will be referred to as a vibration sensor 206.

The signals from each sensing area 214 of the vibration sensor 206 may he processed independently of each other or may be processed together in order to provide the output of the processor. The processing will depend on the positioning of each sensing area 214 and the desired output.

In a second arrangement, as shown in Figure 4, the 2D material film is provided in 35 positions or sensing areas 314. The sensing areas 314 are laid out in a 5 x 7 array on the surface 312 of the casing 302. Each sensing area 314 is of equal size, although this need not necessarily be the case. By providing an array of sensing areas 314, the vibration sensor 306 can monitor a large portion of the casing 302. The use of an array may also allow differentiation of the source position of any sensed vibrations. Use of a large array of sensing areas allows monitoring of a larger proportion of, or the entirety of, the casing of the machine, whilst still allowing problem areas to be pinpointed through comparison of the effect of the detected vibrational characteristic on each individual sensing area.

As with the first arrangement, the signals from each sensing area 314 of the vibration sensor 306 may be processed independently of each other or may be processed together in order to provide the output of the processor. The processing will depend on the positioning of each sensor area 314 and the desired output.

A third arrangement includes a vibration sensor 406 having pseudorandom arrangement of sensing areas 414 on the surface 412 of the casing 402. Whilst the sensing areas 414 are arranged in a 3 x 3 array, each sensing area 414 is of a different shape and/or size to the other sensing areas 414 in the arrangement. The pseudorandom arrangement may be calculated by use of any suitable algorithm. Such algorithms will be known to the skilled person.

Advantageously, pseudorandom or known, irregular arrangements of sensing areas may result in output signals that can allow superior sensing to other arrangements. For example, such arrangements may ensure that regular nodes and antinodes present in a sensed vibration pattern are not inadvertently missed. The sensing pattern must be known, even if irregular or pseudorandom, in order that the vibrational patterns detected can be analysed to provide useful information about the source of any particular vibration or vibrational patter.

The depictions of the arrangement of the sensing areas in each embodiment are highly schematic and used to illustrate the differences between the different arrangements. In practice, the pattern of sensing areas may he a speckle-like pattern, although each sensing area need not be particularly small. Such a speckle-like pattern should be capable of being described mathematically in order that the vibrations can be analysed, but importantly would be capable of detecting patterns that shift temporally, for example by detecting the positions pattern as a particular fault develops. of peaks and troughs in a standing-wave type Figure 5 is a flow chart that depicts a method of monitoring a condition of a rotating machine. In a first step Si, a vibration sensor is provided. The vibration sensor comprises a 2D material film that is attached to a surface of a casing of the rotating machine. The combination of the rotating machine and vibration sensor may be as shown in Figures 1 to 4.

In a second step S2, an output of the vibration sensor is monitored. The monitoring is provided by the use of a processor such as that described in relation to Figure 1. By monitoring the output, a third step S3 of determining a fault or other condition of the rotating machine is possible. Such a fault or condition may include one or more of a wear condition, break or fracture of a component, or may allow a future failure of the rotating machine to be predicted.

Claims

CLAIMS1. A rotating machine comprising: a casing; and a vibration sensor configured to provide an output indicative of a condition of the rotating machine; wherein the vibration sensor includes a 2D material film, the 2D material film being attached to a surface of the casing.
2. A rotating machine according to claim 1, wherein the 2D material film is at least one of a piezoelectric 2D material film and a strain-sensitive 2D material film.
3. A rotating machine according to claim 1 or claim 2, wherein the 2D material film includes graphcnc.
4. A rotating machine according to any preceding claim, wherein the 2D material film is provided in a plurality of positions on the surface of the casing.
5. A rotating machine according to claim 4, wherein the plurality of positions provide a plurality of sensor readings corresponding to spaced points on the surface of the casing.
6. A rotating machine according to claim 4 or claim 5, wherein the plurality of positions provide an array of sensor readings over a portion of the surface of the 25 casing.
7. A rotating machine according to any of claims 4 to 6, wherein the plurality of positions arc arranged in a grid formation.
8. A rotating machine according to any of claims 4 to 7, wherein the plurality of positions are arranged in a pseudorandom formation.
9. A rotating machine according to any preceding claim, wherein the vibration sensor is configured to provide continuous and/or long-term condition monitoring of the rotating machine.
10. A rotating machine according to any preceding claim, wherein the vibration sensor is configured to provide fault condition diagnostics of the rotating machine.
11. A rotating machine according to any preceding claim, wherein the output of the vibration sensor is indicative of a wear condition, break or fracture of a component, and/or failure or predicted failure of the rotating machine.
12. A rotating machine according to any preceding claim, wherein the rotating machine further comprises a processor that is configured to receive the output from the vibration sensor and determine the condition of the rotating machine.
13. A rotating machine according to any preceding claim, wherein the rotating machine comprises an electric motor. 15
14. A method of monitoring a condition of a rotating machine, the method including the steps of: providing a vibration sensor comprising a 2D material film that is attached to a surface of a casing of the rotating machine; and monitoring an output of the vibration sensor, the output being indicative of the condition of the rotating machine.
15. A method according to claim 14, further comprising the step of determining from the output of the vibration sensor whether the rotating machine has a fault or is likely to develop a fault.
16. A method according to claim 15, wherein the fault includes one or more of a wear condition, break or fracture of a component, and/or failure or predicted failure of the rotating machine.