JP2015143711A - vibration characteristic measuring apparatus and vibration characteristic measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration characteristic measuring apparatus and a vibration characteristic measuring method capable of vibrating a rotary body without exceeding an allowable value and acquiring high-quality data without increasing energy consumption at a time of measuring vibration characteristics.SOLUTION: A vibration characteristic measuring apparatus 1 comprises: a magnetic bearing 12 supporting a rotary body of a multistage centrifugal compressor; a displacement sensor 13 measuring the amplitude of the rotary body; and an excitation controller 7 outputting an excitation control signal for exciting the rotary body and measuring response characteristics of a vibration of the rotary body to the excitation control signal, the excitation controller 7 including an excitation response analyzer 9, outputting a rotary-body control signal obtained by adding a vibration cancellation signal for cancelling an imbalanced vibration of the rotary body to the excitation control signal at a time of measuring the response characteristics, generating a forced vibration having an amplitude allowable value based on a state of no imbalanced vibration as maximum amplitude, and measuring the response characteristics of the excited rotary body by the excitation response analyzer 9. Furthermore, a vibration characteristic measuring method for the vibration characteristic measuring apparatus 1 is provided.

Description

  The present invention relates to a vibration characteristic measuring apparatus and a vibration characteristic measuring method for measuring vibration characteristics of a rotating shaft of a rotary machine such as a multistage centrifugal compressor.

Multistage centrifugal compressors that are placed in oil fields, natural gas plants, petrochemical plants, etc. and compress compressed fluids such as various gases and liquids rotate a centrifugal impeller with multiple stages together with a rotating shaft, and are covered by centrifugal force. It is a rotating machine that compresses compressed fluid.
Such a multistage centrifugal compressor has a sealing mechanism including an annular sealing member centering on the axis of the rotating shaft in order to prevent leakage of the fluid to be compressed from each stage of the centrifugal impeller. It is equipped.
In the sealing mechanism provided in the multistage centrifugal compressor, a destabilizing force is generated due to the leakage flow of the fluid to be compressed, and this destabilizing force affects the rotational stability of the rotating shaft and the centrifugal impeller. That is, when the destabilizing force exceeds the stabilizing force, self-excited vibration called seal whirl occurs.

  Therefore, it is important that the rotating machine is designed to generate a sufficiently large stabilizing force against the destabilizing force generated in the seal mechanism. For this purpose, it is necessary to measure the vibration characteristics of the rotating body including the rotating shaft, grasp the characteristics, and evaluate the stability based on the vibration characteristics.

  For example, Patent Document 1 discloses a technique for actually measuring the vibration characteristics of a rotating machine during operation by applying vibration to a bearing portion and analyzing vibration generated on a rotating shaft by the vibration. Further, in Non-Patent Document 1, an active radial magnetic bearing is attached to the end of the rotary shaft of the compressor, an excitation current is supplied to the magnetic bearing to vibrate the rotary shaft, and the vibration characteristics of the rotary shaft are determined. A technique for actual measurement is disclosed.

Japanese Patent Publication No. 5-5057

Pettinato and two others, “Shop Acceptance Testing of Compressor Rotational Stability and Theoretical Correlation”, 39th Turbomachinery Symposium, Texas, pp. 31-42

The techniques described in Patent Document 1 and Non-Patent Document 1 are techniques for measuring vibration characteristics of a rotating shaft by exciting a rotating rotating shaft and measuring vibration (amplitude and phase) of the rotating shaft. It is.
Thus, when measuring the vibration characteristics of a rotating body such as a rotating shaft, it is preferable that the excitation amplitude is large in order to obtain high quality data with little variation. By increasing the amplitude of the rotating body that vibrates by excitation, the signal-to-noise ratio of the signal output by the sensor that measures vibration can be improved, and high-quality data can be acquired as data indicating the amplitude.

On the other hand, when the amplitude of the rotating rotating body increases due to vibration, if the amplitude exceeds an allowable value determined as a design value, for example, the sealing member provided in the sealing mechanism comes into contact with the rotating body and the sealing mechanism. Problems such as wear. Therefore, it is necessary to vibrate in a range where the amplitude generated in the rotating body does not exceed the allowable value.
However, the rotating body of the rotating machine vibrates in an amplitude range that does not exceed the allowable value even during normal rotation due to mass deviation or the like. Therefore, the amplitude of vibration that can be generated by exciting the rotating body during rotation is limited to a range between the amplitude of vibration during normal rotation and a margin of allowable values. In other words, the vibration that can be generated in the rotating shaft by vibration is suppressed to a small value, and the SN ratio of the signal output from the sensor that measures the vibration is deteriorated. And there exists a problem that the quality of the data (data which shows the vibration characteristic of a rotating shaft) acquired based on this signal falls.

For example, when the quality of acquired data is poor, vibration analysis can be performed by greatly increasing the number of acquired data and performing an averaging process.
However, when a large amount of data is acquired to perform the averaging process, there is a problem that it takes time to acquire the data and man-hours increase. In addition, there is a problem that the operation time of the rotating shaft and the time for vibration are increased in order to acquire a large amount of data, and the amount of energy consumption increases.

  Therefore, the present invention provides a vibration characteristic measuring apparatus and a vibration characteristic measuring method that can vibrate a rotating body without exceeding an allowable value and obtain high quality data without increasing energy consumption when measuring vibration characteristics. The issue is to provide.

  In order to solve the above problems, the present invention provides a magnetic bearing that supports a rotating body of a rotating machine in a non-contact manner, a measuring device that measures an amplitude when the rotating body vibrates, and a current supply that supplies a current to the magnetic bearing. And a vibration control signal for controlling the magnetic bearing so as to vibrate the rotating body, and vibration of the rotating body with respect to the vibration control signal based on the amplitude measured by the measuring device And a vibration control device that measures a response characteristic to the vibration control signal. The vibration control device includes a vibration response analysis device and a balance signal generation device. When measuring the response characteristics, the vibration control device generates unbalance vibration generated when the rotating body rotates. A vibration elimination signal for elimination by a bearing is generated by the balancing signal generator to eliminate the unbalanced vibration, and a rotating body control signal obtained by adding the vibration elimination signal to the excitation control signal is output. The forced vibration is generated by generating a forced vibration whose maximum amplitude is an allowable amplitude based on a state in which there is no unbalanced vibration, and the response characteristic of the excited rotating body is excited. Measured with a response analyzer. Further, a vibration characteristic measuring method in this vibration characteristic measuring apparatus is used.

According to the present invention, a vibration characteristic measuring apparatus and a vibration characteristic measuring method capable of acquiring high-quality data without increasing energy consumption by vibrating a rotating body without exceeding an allowable value when measuring vibration characteristics are provided. it can.
The vibration characteristics can be measured without causing problems such as damage to the bearing and the seal mechanism and wear of the seal mechanism.

(A) is the schematic block diagram which looked at the multistage centrifugal compressor which attached the vibration characteristic measuring apparatus which concerns on this embodiment from the side, (b) is the magnetic bearing of a vibration characteristic measuring apparatus, and the rotating shaft of a multistage centrifugal compressor is A. It is the schematic seen from the direction. (A) is the figure which modeled the unbalance vibration of a rotating shaft, (b) is a figure for demonstrating the margin of the amplitude and allowable value of a rotating shaft. It is a figure which shows the functional block of a vibration characteristic measuring apparatus. (A) is a figure which shows the amplitude of the X-axis direction of a rotating shaft when vibrating with the conventional vibration characteristic measuring apparatus, (b) is a rotating shaft when vibrating with the vibration characteristic measuring apparatus which concerns on this embodiment. It is a figure which shows the amplitude of a X-axis direction. It is a figure which compares the amplitude of a rotating shaft, and the margin of an allowable value with a prior art example and this embodiment. It is a figure which shows the functional block of a vibration characteristic measuring apparatus provided with the vibration control apparatus which has a vibration signal circuit breaker.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
As shown in FIG. 1A, the vibration characteristic measuring apparatus 1 according to this embodiment is attached to a rotary machine such as a multistage centrifugal compressor 50 and vibrates a rotary body including a rotary shaft 51 and a centrifugal impeller 53. It is a device that can measure characteristics.
The vibration characteristic measuring apparatus 1 according to the present embodiment is not limited to the multistage centrifugal compressor 50, and can be attached to a rotary machine (turbine, electric motor, etc.) having a rotating body such as the rotary shaft 51. An example attached to the machine 50 will be described.

  A multistage centrifugal compressor 50 configured as shown in FIG. 1A is a device that continuously compresses a fluid to be compressed, such as gas, by the centrifugal force of a centrifugal impeller 53 that rotates together with a rotating shaft 51. The rotation shaft 51 is rotationally driven by a drive source (such as an electric motor) (not shown).

  The centrifugal impeller 53 is provided in multiple stages in the axial direction of the rotary shaft 51 and rotates together with the rotary shaft 51 to compress the compressed fluid sucked from the center side (rotary shaft 51 side) and discharge it from the outer periphery with centrifugal force. It is configured.

The rotating shaft 51 is rotatably supported by a plurality of bearing members. For example, the rotary shaft 51 is supported in the radial direction by bearing members 52a and 52b provided at two locations so as to sandwich the centrifugal impeller 53 in the axial direction. Further, the bearing member 52c that supports the rotating shaft 51 in the axial direction restricts the variation of the rotating shaft 51 in the axial direction.
Thus, the rotating shaft 51 is rotatably supported by the plurality of bearing members 52a to 52c.

The centrifugal impeller 53 is housed in a housing 54 that is a stationary body, and the compressed fluid taken in from the inlet portion 54a is compressed by the multistage centrifugal impeller 53 and discharged from the outlet portion 54b.
Hereinafter, structures that include the rotating shaft 51 and the centrifugal impeller 53 and rotate integrally with the rotating shaft 51 may be collectively referred to as “rotating bodies”. In addition, structures (such as the housing 54) that are stationary with respect to the rotating body may be collectively referred to as “stationary bodies”.

  In the multistage centrifugal compressor 50 configured as described above, when the compressed fluid taken in from the inlet portion 54a of the housing 54 is discharged from the housing 54 without passing through the centrifugal impeller 53, the compressed fluid is not compressed. Thus, the gas is discharged from the outlet portion 54b, and the compression efficiency of the multistage centrifugal compressor 50 is reduced. Therefore, in order to improve the compression efficiency, a sealing mechanism 55 is appropriately provided so as to seal the gap between the housing 54 (stationary body) and the rotating shaft 51 or the centrifugal impeller 53 (rotating body).

The seal mechanism 55 is, for example, for preventing the upstream stage (the inlet part 54a side) of the centrifugal impeller 53 from flowing into the downstream stage (the outlet part 54b side) through the gap between the centrifugal impeller 53 and the housing 54. The gap between the housing 54 and the centrifugal impeller 53 is sealed.
Further, both end portions of the centrifugal impeller 53 in the axial direction are provided with seal mechanisms 55 for sealing the gap between the housing 54 and the rotary shaft 51.

The sealing mechanism 55 appropriately provided as described above has a sealing member (not shown) provided so that a minute clearance is formed between the stationary body and the rotating body, and is configured to prevent the flow of the fluid to be compressed. The
Further, by forming the clearance, for example, the seal member of the seal mechanism 55 provided in the stationary body is prevented from coming into contact with the rotating body, and wear of the seal member is suppressed.
FIG. 1 shows a configuration in which the seal mechanism 55 is provided in the stationary body (housing 54). However, the seal mechanism 55 is provided in the rotating body (rotary shaft 51, centrifugal impeller 53, etc.). Also good. Further, the sealing mechanism 55 may be provided in a stationary body other than the housing 54.

A rotating body configured to include the rotating shaft 51, the centrifugal impeller 53, and the like generates minute vibrations (unbalanced vibrations) when the circumferential mass is not uniform and rotates.
If the mass of the rotating body is not uniform in the circumferential direction, the rotating body can be modeled so that one point in the circumferential direction becomes a mass concentration point (mass concentration point G) as shown in FIG. it can. When the rotating body having the mass concentration point G rotates, centrifugal force acts on the mass concentration point G and is drawn outward, and the rotating body is displaced toward the mass concentration point G. Such displacement continuously occurs as the rotating body rotates, and unbalanced vibration occurs.
2X and 12Y shown in FIG. 2A are electromagnets of the magnetic bearing 12 provided in the vibration characteristic measuring apparatus 1 (see FIG. 1A) so as to support the rotating shaft 51 in a non-contact manner.

Thus, since unbalanced vibration occurs in the rotating body, the seal mechanism 55 provided in the stationary body may have a clearance so as not to contact the rotating body even when unbalanced vibration occurs. Although it is preferable, when the clearance is increased, the sealing performance for preventing the flow of the fluid to be compressed is lowered.
Therefore, there is a case where the unbalanced vibration of the rotating body is constantly monitored and the operation of the rotating body is managed so that the amplitude does not exceed a predetermined allowable value.

Further, in a rotary machine such as the multistage centrifugal compressor 50 (see FIG. 1A), in order to evaluate the stability of the rotating body against the natural vibration mode, the response characteristic of the shaft vibration generated in the rotating body is used as the vibration characteristic. Vibration characteristic measurement to be measured is required.
The stability of the rotating body against axial vibration can be evaluated by exciting the rotating body and measuring the response characteristics of the vibration of the rotating body caused thereby.
Therefore, when evaluating the stability of the rotating body against axial vibration, the rotating body is forcibly vibrated, that is, vibrated, and the amplitude and phase of the rotating body vibration at that time are measured. The response characteristic of the output (actual vibration of the rotating body) with respect to the input (vibration applied to the rotating body) is measured.

As shown in FIG. 1A, the vibration characteristic measuring apparatus 1 according to this embodiment that can be attached to a multistage centrifugal compressor 50 vibrates the rotating body in order to evaluate the stability of the axial vibration of the rotating body. Furthermore, it is a device that measures vibration (amplitude and phase) of the excited rotating body and measures the response characteristics of the vibration.
Therefore, the vibration characteristic measuring device 1 includes a magnetic bearing 12 that vibrates the rotating shaft 51 and a measuring device (displacement sensor 13) that measures the amplitude (displacement) of the rotating shaft 51.
The magnetic bearing 12 includes electromagnets 12X and 12Y (see FIG. 1B), and supports the rotating shaft 51 in a non-contact manner by a magnetic force generated by a current supplied to a coil (not shown). Is the original function.

  As shown in FIG. 1B, the Y axis in the vertical vertical direction (second direction) on the plane having the axis of the rotation shaft 51 as the normal line (the first direction and the first direction) Set the X-axis to According to this configuration, the X-axis direction (first direction) is a direction orthogonal to the axial direction of the rotating shaft 51 (rotating body), and the Y-axis direction (second direction) is the axial direction of the rotating shaft 51. And a direction orthogonal to the X-axis direction (first direction).

As shown in FIG. 1B, in the coordinate system in which the rotation center of the rotation shaft 51 is the origin O, the magnetic bearing 12 includes the electromagnet 12X sandwiching the rotation shaft 51 in the lateral direction on the X axis. The electromagnet 12Y is arranged so as to sandwich the rotary shaft 51 in the vertical direction on the Y axis. The gap between the rotating shaft 51 and the electromagnet 12X can be adjusted by controlling the current supplied to the electromagnet 12X, and the gap between the rotating shaft 51 and the electromagnet 12Y can be adjusted by controlling the current supplied to the electromagnet 12Y.
Further, by continuously adjusting the gap between the rotating shaft 51 and the electromagnet 12X, the rotating shaft 51 can be vibrated in the X-axis direction, and by continuously adjusting the gap between the rotating shaft 51 and the electromagnet 12Y, The rotating shaft 51 can be vibrated in the Y-axis direction. In this way, the rotating shaft 51 can be vibrated by the magnetic bearing 12.

  For example, a cosine wave current is supplied to the electromagnet 12X so as to periodically adjust the gap between the rotary shaft 51 and the electromagnet 12X, and the gap between the rotary shaft 51 and the electromagnet 12Y is set at the same cycle as the gap between the rotary shaft 51 and the electromagnet 12X. When a sine wave current that is adjusted so that the phase is shifted by 90 degrees is supplied to the electromagnet 12Y, the rotating shaft 51 can be vibrated so as to swing around the axis.

  The displacement sensor 13 shown in FIG. 1A includes, for example, an X displacement sensor 13X that measures the amount of displacement of the rotating shaft 51 in the X axis direction due to vibration and a Y displacement sensor 13Y that measures the amount of displacement in the Y axis direction. Thus, the vibration displacement of the rotating shaft 51 is measured by the amount of displacement in the X-axis direction and the amount of displacement in the Y-axis direction. The type of the displacement sensor 13 is not limited. For example, an eddy current type sensor capable of measuring the displacement of the rotating shaft 51 in a non-contact manner can be used.

Conventionally, the vibration characteristic measuring apparatus 1 vibrates the rotating shaft 51 with the magnetic bearing 12 while the rotating body is rotating, and measures the displacement amount of the rotating shaft 51 in the X-axis direction and the Y-axis direction with the displacement sensor 13. Thus, the vibration displacement of the rotating shaft 51 is measured.
At this time, since the rotating body is rotating, the unbalanced vibration described above is generated. Therefore, when the rotating shaft 51 is vibrated, vibration due to vibration (hereinafter referred to as forced vibration) occurs in addition to unbalanced vibration, and the amplitude of the rotating body increases.
As described above, in order to avoid contact between the sealing mechanism 55 provided in the stationary body and the rotating body, the amplitude of the rotating body is required to be smaller than a predetermined allowable value. Therefore, a vibration that maximizes the amplitude corresponding to the margin between the amplitude due to the unbalanced vibration and the allowable value can be input to the rotating body in which the unbalanced vibration is generated.

In other words, the magnitude of forced vibration due to vibration is limited. That is, as shown in FIG. 2B, the amplitude of the unbalanced vibration V1 is used as a reference, and the amplitude of the forced vibration V2 is suppressed within a margin (margin 1) from the reference amplitude to the allowable value. Required.
Therefore, the amplitude of the rotating shaft 51 due to forced vibration is reduced, and the SN ratio of the signal indicating the displacement of the rotating shaft 51 (displacement signal) output from the displacement sensor 13 is deteriorated.

Therefore, the vibration characteristic measuring apparatus 1 according to the present embodiment is configured so as to give a large amplitude vibration to the rotating rotating shaft 51 and to maintain a good S / N ratio of the displacement signal output from the displacement sensor 13. Yes.
Specifically, the vibration characteristic measuring apparatus 1 includes a balancing signal generator 8 as shown in FIG. 3, and is configured to temporarily cancel the unbalanced vibration when measuring the response characteristics of the rotating body.

As shown in FIG. 2A, the balancing signal generator 8 continuously generates a force that counteracts the centrifugal force acting on the mass concentration point G by the magnetic force of the magnetic bearing 12. The displacement to the concentrated point G side is canceled to cancel the unbalanced vibration of the rotating body.
As described above, the vibration characteristic measuring apparatus 1 according to the present embodiment is a current supply apparatus according to the present embodiment, which generates a signal for eliminating the unbalanced vibration of the rotating body by the balance signal generator 8 shown in FIG. It has a function of inputting to the current amplifier 11 (see FIG. 3). The current amplifier 11 supplies the magnetic bearing 12 with a current obtained by amplifying the input signal (signal for eliminating unbalanced vibration) with a predetermined gain.

The current supplied from the current amplifier 11 to the magnetic bearing 12 is preferably a current obtained by amplifying the input signal with a predetermined gain, and is synchronized with the input signal. With this configuration, the magnetic bearing 12 to which current is supplied from the current amplifier 11 can generate a magnetic force according to a signal input to the current amplifier 11.
In addition, if the current supply device is a device capable of supplying the magnetic bearing 12 with a current that generates a magnetic force according to the input signal, the current amplifier 11 supplies a current obtained by amplifying the input signal to the magnetic bearing 12. It is not limited to.

The balancing signal generator 8 shown in FIG. 3 includes a so-called two-phase oscillator, and its oscillation frequency is required to be synchronized with the rotation frequency of the rotating body. Therefore, a rotation pulse signal Rp indicating the rotation speed of the rotating body is input to the balancing signal generator 8. For example, the rotation speed sensor (not shown) may measure the rotation reference groove carved on the rotation shaft 51 and input the result to the balancing signal generator 8 as the rotation pulse signal Rp.
The balancing signal generator 8 incorporates a phase-locked loop circuit (PLL circuit) using the input rotation pulse signal Rp as a reference signal, and a sine wave signal and a cosine wave signal synchronized with the rotation frequency of the rotating body. Is configured to oscillate. The sine wave signal and the cosine wave signal oscillated by the PLL circuit are single frequency signals whose phases are different by 90 degrees.

Moreover, as shown in FIG. 3, the counterbalance amplitude Am and phase Ph of the unbalance vibration are input to the counterbalance signal generator 8 respectively. Here, the phase Ph indicates a phase obtained by delaying a shift of the rotation angle of the rotating body from the rotation angle of the mass concentration point G shown in FIG. That is, the rotation angle of the mass concentration point G (indicated by θa in FIG. 2A) when the rotator is at the reference position (for example, the rotation angle is “0”) is delayed by 180 degrees (FIG. 2). (Indicated by θb in (a)).
In this way, by setting the phase Ph delayed by 180 degrees from the rotation angle of the mass concentration point G, a force in a direction to cancel the centrifugal force acting on the mass concentration point G can be generated.
Further, the canceling amplitude Am indicates an amount for canceling the centrifugal force acting on the mass concentration point G.

  The canceling amplitude Am and the phase Ph are, for example, not generated by the administrator of the vibration characteristic measuring apparatus 1 (see FIG. 1A) in the rotating body of the multistage centrifugal compressor 50 (see FIG. 1A). What is necessary is just to set it as the value acquired by measuring a balance vibration, and also inputting with an input device which is not illustrated. If the input cancellation amplitude Am and phase Ph are stored in a storage unit (not shown), the balancing signal generator 8 can read and use the cancellation amplitude Am and phase Ph as necessary.

The balancing signal generator 8 combines the cosine wave signal and sine wave signal oscillated by the PLL circuit with the cancellation amplitude Am and the phase Ph, and generates an oscillation signal in the X-axis direction as shown in the following equations (1a) and (1b). Fx and the oscillation signal Fy in the Y-axis direction are generated as shown in FIG.
Fx = Am · Cos (Ωt + Ph) (1a)
Fy = Am · Sin (Ωt + Ph) (1b)
Here, Ω represents the rotational angular velocity of the rotating body, and t represents time.
Further, the rotation angular velocity Ω is a value calculated based on, for example, the input rotation pulse signal Rp.
Thus, the balancing signal generator 8 generates the oscillation signals Fx and Fy whose amplitude is both Am and whose phases are shifted from each other by 90 degrees.
Thus, the balancing signal generator 8 includes the oscillation signal Fx in the X-axis direction including the cosine wave component (Am · Cos (Ωt + Ph)) and the Y including the sine wave component (Am · Sin (Ωt + Ph)). An axial oscillation signal Fy is generated.

The oscillation signals Fx and Fy shown in the equations (1a) and (1b) are output from the balancing signal generator 8 and input to the X amplifier 11X and the Y amplifier 11Y of the current amplifier 11, respectively.
The X amplifier 11X amplifies the input oscillation signal Fx with a predetermined gain and supplies it to the electromagnet 12X. The Y amplifier 11Y amplifies the input oscillation signal Fy with a predetermined gain (for example, a gain equivalent to the gain of the X amplifier 11X) and supplies the amplified signal to the electromagnet 12Y. The gains of the X amplifier 11X and the Y amplifier 11Y are preferably set as appropriate according to the characteristics of the magnetic bearing 12 and the vibration characteristics of the rotating body.

When a current output from the current amplifier 11 (X amplifier 11X, Y amplifier 11Y) is supplied to the electromagnet 12X and the electromagnet 12Y, a signal (synthetic oscillation) is combined with the magnetic bearing 12 in the X-axis direction and the Y-axis direction. A current obtained by amplifying the signal Fz) is supplied. This synthesized oscillation signal Fz is represented by the following expression (2) in complex number notation.
Fz = Fx + jFy = Am · ej (Ωt + Ph) (2)
J represents an imaginary unit.

  From the equation (2), it can be seen that the combined oscillation signal Fz is a signal that swings in a circle with a radius Am on the complex plane as time t passes. Therefore, if the electromagnets 12X and 12Y arranged so as to be orthogonal to each other around the rotating body in the magnetic bearing 12 generate magnetic forces corresponding to the oscillation signals Fx and Fy, respectively, In synchronism with the rotation, the force swings in a circle around the rotation center of the rotating body.

Further, a force generated by unbalanced vibration and displacing the rotating body (hereinafter referred to as unbalanced force) is also a force that swings in a circle centering on the rotation center of the rotating body in synchronization with the rotation of the rotating body. This unbalanced force is generated by the centrifugal force acting on the mass concentration point G shown in FIG. 2A, and the phase Ph of the oscillation signals Fx and Fy is an angle obtained by delaying the rotation angle of the mass concentration point G by 180 degrees. Therefore, the unbalanced vibration of the rotating body can be eliminated by the magnetic force generated in the magnetic bearing 12 to which the cosine wave current and the sine wave current obtained by amplifying the oscillation signals Fx and Fy are supplied.
In other words, the combined oscillation signal Fz eliminates the cosine wave component (Am · Cos (Ωt + Ph)) that eliminates vibration in the X-axis direction and the sine wave component (Am · Sin (Ωt + Ph)) that eliminates vibration in the Y-axis direction. It becomes a vibration elimination signal as a component.
The balancing signal generator 8 generates the oscillation signals Fx and Fy in this way, and further generates a combined oscillation signal (vibration elimination signal) Fz obtained by synthesizing the oscillation signals Fx and Fy to eliminate the unbalanced vibration of the rotating body. To do.

Further, the vibration characteristic measuring apparatus 1 includes an excitation response analyzing apparatus 9 as shown in FIG. The vibration response analyzer 9 generates vibration signals Ex and Ey for vibrating the rotating body. The excitation signal Ex is a control signal for exciting the rotating body in the X-axis direction, and the excitation signal Ey is a control signal for exciting the rotating body in the Y-axis direction. A signal including at least one of the vibration signals Ex and Ey as a component is referred to as a vibration control signal.
According to this configuration, the vibration signal Ex becomes a component of the vibration control signal (first direction vibration component) that vibrates the rotating body in the X-axis direction, and the vibration signal Ey moves the rotating body in the Y-axis direction. Is a component of the vibration control signal (second direction vibration component).

The vibration response analyzing apparatus 9 according to the present embodiment outputs, for example, a sine wave signal having an arbitrary amplitude as the vibration signal Ex in the X-axis direction and the vibration signal Ey in the Y-axis direction while changing the cycle. The signals are input to the X amplifier 11X and the Y amplifier 11Y of the amplifier 11, respectively.
When the current obtained by amplifying the excitation signal Ex, which is a sine wave signal, by the X amplifier 11X is supplied to the electromagnet 12X, the rotating body is excited in the X-axis direction. When the current obtained by amplifying the excitation signal Ey, which is a sine wave signal, by the Y amplifier 11Y is supplied to the electromagnet 12Y, the rotating body is excited in the Y-axis direction.

  Further, a displacement signal indicating the displacement of the rotating body measured by the displacement sensor 13 is input to the vibration response analyzer 9. The X displacement sensor 13X measures the displacement of the rotating body in the X axis direction and inputs the measurement result as an X displacement signal Mx to the vibration response analyzer 9. The Y displacement sensor 13Y detects the displacement of the rotating body in the Y axis direction. And the measurement result is input to the vibration response analyzer 9 as the Y displacement signal My.

When the excitation signal Ex in the X-axis direction is a sine wave signal, the excitation response analyzer 9 outputs the excitation signal Ex while changing the period with time, and rotates based on the input X displacement signal Mx. The displacement of the body in the X-axis direction is acquired as data. Then, the response characteristic (frequency characteristic) in the X-axis direction of the rotating body with respect to the excitation signal Ex (sine wave signal) is measured.
Similarly, when the excitation signal Ey in the Y-axis direction is a sine wave signal, the excitation response analyzer 9 outputs the excitation signal Ey while changing the period with the passage of time, and the input Y displacement signal My Based on this, the displacement in the Y-axis direction of the rotating body is acquired as data. Then, the response characteristic (frequency characteristic) of the rotating body in the Y-axis direction with respect to the excitation signal Ey (sine wave signal) is measured.
In this way, the vibration response analyzing apparatus 9 outputs (the X displacement signal Mx, the Y displacement signal My) of the rotating body with respect to the input to the rotating body (the X-axis direction excitation signal Ex, the Y-axis direction excitation signal Ey). ) Is measured.

For example, as shown in FIG. 4A, when the vibration response analyzer 9 vibrates the rotating body in the X-axis direction in order to measure the response characteristics in the X-axis direction, In the vibration execution period), the displacement in the X-axis direction, that is, the amplitude changes according to the change in the period of the excitation signal Ex in the X-axis direction, and a response characteristic having the maximum amplitude at a specific frequency is obtained.
However, since the unbalanced vibration is generated in the rotating body even during the vibration execution period, the amplitude of the forced vibration due to the vibration is an amplitude superimposed on the amplitude of the unbalanced vibration. The amplitude of the rotating body that is forcibly oscillated is larger than the amplitude of the rotating body that is not vibrated. Therefore, the amplitude that can be generated in the rotating body by the vibration is as shown in FIG. 2B (shown again as (conventional example) in FIG. 5), and the amplitude of the unbalanced vibration and the allowable value described above. The margin is limited to a range of 1.

That is, as shown in FIG. 5 (conventional example), the amplitude of the unbalanced vibration V1 appears as a reference, and the amplitude of the forced vibration V2 appears as an increase from the reference amplitude. Therefore, the amplitude of the forced vibration V2 is limited to an amplitude corresponding to a margin 1 between the reference amplitude (the amplitude of the unbalanced vibration V1) and the allowable value. Thus, the amplitude that can be generated by exciting the rotating body is limited. That is, the maximum amplitude of the forced vibration V2 is limited to be small, and the S / N ratio of the X displacement signal Mx output by the X displacement sensor 13X measuring the maximum amplitude is deteriorated. And the quality of the data of the displacement of the X-axis direction which the vibration response analyzer 9 acquires decreases.
Similarly, the quality of the displacement data in the Y-axis direction also decreases.

  Therefore, as shown in FIG. 3, the vibration characteristic measuring apparatus 1 (see FIG. 1A) adds an oscillation signal Fx and an excitation signal Ex, and adds an oscillation signal Fy and an excitation signal Ey. 7a. In the present embodiment, the vibration control device 7 of the vibration characteristic measuring device 1 includes the balance signal generator 8, the vibration response analyzer 9, and the adder 7a.

When measuring the response characteristics of the rotating body, the vibration characteristic measuring device 1 generates an vibration control signal by the vibration response analyzing device 9 of the vibration control device 7, and further generates a vibration cancellation signal by the balancing signal generator 8. Occur. Then, an adder 7a generates an addition signal ADDx obtained by adding the oscillation signal Fx in the X-axis direction of the vibration elimination signal and the excitation signal Ex in the X-axis direction of the excitation control signal. Similarly, an addition signal ADDy is generated by adding the oscillation signal Fy in the Y-axis direction of the vibration elimination signal and the excitation signal Ey in the Y-axis direction of the excitation control signal.
The addition signal ADDx is input to the X amplifier 11X, and a current obtained by amplifying the addition signal ADDx by the X amplifier 11X is supplied to the electromagnet 12X of the magnetic bearing 12 (see FIG. 1B).
The addition signal ADDy is input to the Y amplifier 11Y, and a current obtained by amplifying the addition signal ADDy by the Y amplifier 11Y is supplied to the electromagnet 12Y (see FIG. 1B) of the magnetic bearing 12.

That is, the vibration control device 7 outputs a signal obtained by adding the vibration elimination signal (synthetic oscillation signal Fz) and the vibration control signal (hereinafter referred to as a rotator control signal).
The rotator control signal includes a cosine wave component of the vibration elimination signal, an addition signal ADDx including a component obtained by adding the first direction excitation component of the oscillation control signal, a sine wave component of the vibration elimination signal, and an excitation It is a synthesized signal composed of an addition signal ADDy including a component obtained by adding the second direction excitation component of the control signal.
The addition signal ADDx is a signal obtained by adding the oscillation signal Fx in the X-axis direction and the excitation signal Ex. The component of the oscillation signal Fx in the X-axis direction of the rotating body and the component of the excitation signal Ex in the X-axis direction are added. The added signal is included.
The addition signal ADDy is a signal obtained by adding the oscillation signal Fy in the Y-axis direction and the excitation signal Ey, and the component of the oscillation signal Fy in the Y-axis direction of the rotating body and the component of the excitation signal Ey in the Y-axis direction. It becomes the addition signal containing.

  Therefore, the rotating body control signal including the addition signals ADDx and ADDy as components includes the component of the oscillation signal Fx in the X-axis direction, the component of the oscillation signal Fy in the Y-axis direction, and the component of the excitation signal Ex in the X-axis direction. , A signal including a component of the excitation signal Ey in the Y-axis direction. When the current obtained by amplifying the rotating body control signal by the current amplifier 11 is supplied to the magnetic bearing 12, the component of the oscillation signal Fx in the X-axis direction and the oscillation signal Fy in the Y-axis direction are supplied to the magnetic bearing 12. A current including a component, a component of the excitation signal Ex in the X-axis direction, and a component of the excitation signal Ey in the Y-axis direction is supplied.

According to this configuration, during the excitation execution period, the unbalanced vibration of the rotating body is eliminated by the components of the oscillation signals Fx and Fy of the current supplied to the magnetic bearing 12, and the rotating body is driven by the components of the excitation signals Ex and Ey. Excitation is performed in the X-axis direction and the Y-axis direction. Accordingly, as shown in FIG. 4B, unbalanced vibration does not occur in the X-axis direction during the vibration execution period, and only forced vibration due to vibration occurs. The amplitude of the rotating body in the X-axis direction is the amplitude of forced vibration. Although not shown, unbalanced vibration does not occur in the Y-axis direction, and only forced vibration due to excitation occurs. The amplitude of the rotating body in the Y-axis direction is the amplitude of forced vibration.
As a result, the X displacement sensor 13X (see FIG. 3) measures only the amplitude of the forced vibration in the X-axis direction, and the measurement result is used as the X displacement signal Mx (see FIG. 3). Reference). Similarly, the Y displacement sensor 13Y (see FIG. 3) measures only the amplitude of the forced vibration in the Y-axis direction, and uses the measurement result as a Y displacement signal My (see FIG. 3) as an excitation response analyzer 9 (see FIG. 3). Can be entered.

That is, as shown in FIG. 5 (this embodiment), a state where there is no amplitude of unbalanced vibration, in other words, a state where the amplitude is “0” can be used as a reference, and the amplitude of the forced vibration V2 is “0”. Appears as an increase from Therefore, the amplitude of the forced vibration V2 only needs to be within an amplitude range corresponding to a margin (margin 2) between “0” and the allowable value, and the amplitude that can be generated by exciting the rotating body can be expanded. Further, the maximum amplitude of the forced vibration V2 can be expanded to an amplitude corresponding to a margin 2 between “0” and an allowable value, and the X displacement signal output by the X displacement sensor 13X (see FIG. 3) measuring the maximum amplitude. The SN ratio of Mx (see FIG. 3) can be improved. Similarly, the SN ratio of the Y displacement signal My (see FIG. 3) output by measuring the maximum amplitude by the Y displacement sensor 13Y (see FIG. 3) can be improved.
The quality of the displacement data in the X-axis direction and the displacement data in the Y-axis direction acquired by the vibration response analyzer 9 can be improved.

In addition, the vibration characteristic measuring apparatus 1 is configured to be capable of independently measuring the response characteristic in the X-axis direction and the response characteristic in the Y-axis direction of the rotating body of the multistage centrifugal compressor 50 (see FIG. 1A). You can also
For example, when measuring the response characteristic in the X-axis direction alone, the vibration response analyzer 9 outputs the oscillation signal Fx in the X-axis direction output from the balancing signal generator 8 and the vibration response analyzer 9. An addition signal ADDx obtained by adding the excitation signal Ex in the X-axis direction is input to the X amplifier 11X.
Further, the oscillation signal Fy in the Y-axis direction output from the balancing signal generator 8 is input to the Y amplifier 11Y. That is, the addition signal ADDy that makes the excitation signal Ey in the Y-axis direction zero is input to the Y amplifier 11Y.
At this time, the magnetic bearing 12 is supplied with a current including the component of the oscillation signal Fx in the X-axis direction, the component of the oscillation signal Fy in the Y-axis direction, and the component of the excitation signal Ex in the X-axis direction. The

The X displacement sensor 13X (see FIG. 3) measures the displacement of the rotating body in the X-axis direction and inputs the X displacement signal Mx (see FIG. 3) to the vibration response analyzer 9 (see FIG. 3).
In the rotating body, the unbalanced vibration in the X-axis direction is eliminated by the component of the oscillation signal Fx in the X-axis direction of the current supplied to the magnetic bearing 12, and the X displacement sensor 13X measures the amplitude of the rotating body that vibrates by excitation. it can.

Similarly, the vibration response analyzer 9 adds the Y-axis direction oscillation signal Fy output from the balancing signal generator 8 and the Y-axis direction vibration signal Ey output from the vibration response analyzer 9. The signal ADDy is input to the Y amplifier 11Y. Further, an addition signal ADDx for setting the X-axis direction excitation signal Ex to zero is input to the X amplifier 11X. In this way, the displacement of the rotating body in the Y-axis direction can be measured by the Y displacement sensor 13Y (see FIG. 3).
The rotating body eliminates the unbalanced vibration in the Y-axis direction due to the component of the oscillation signal Fy in the Y-axis direction of the current supplied to the magnetic bearing 12, and the Y displacement sensor 13Y measures the amplitude of the rotating body that vibrates due to the excitation. it can.
Thus, the structure which can each measure the response characteristic of the X-axis direction of a rotary body and the response characteristic of a Y-axis direction independently may be sufficient.

As described above, the vibration characteristic measuring apparatus 1 (see FIG. 1A) according to the present embodiment includes a rotating body (rotating shaft 51 (see FIG. 1A)) provided in the multistage centrifugal compressor 50 (see FIG. 1A). 1 (see (a) of FIG. 1), when measuring the response characteristics of the centrifugal impeller 53 (see (a) of FIG. 1)), the oscillation signals Fx and Fy generated by the balancing signal generator 8 (see FIG. 3) Then, the excitation signals Ex and Ey generated by the excitation response analyzer 9 (see FIG. 3) are added by the adder 7a (see FIG. 3), and the component of the oscillation signal Fx in the X-axis direction and the excitation in the X-axis direction are added. An addition signal ADDx (see FIG. 3) including the component of the signal Ex, and an addition signal ADDy (see FIG. 3) including the component of the oscillation signal Fy in the Y-axis direction and the component of the excitation signal Ey in the Y-axis direction are generated. To do.
The addition signals ADDx and ADDy are input to the current amplifier 11 (X amplifier 11X (see FIG. 3), Y amplifier 11Y (see FIG. 3)) as an output signal from the vibration control device 7 (see FIG. 3).
The X amplifier 11X supplies the current obtained by amplifying the addition signal ADDx to the electromagnet 12X (see FIG. 3) of the magnetic bearing 12, and the Y amplifier 11Y supplies the current obtained by amplifying the addition signal ADDy to the electromagnet 12Y (FIG. 3). Supply).

  The rotating body includes the component of the oscillation signal Fx in the X-axis direction included in the current supplied to the electromagnet 12X (see FIG. 3) and the oscillation in the Y-axis direction included in the current supplied to the electromagnet 12Y (see FIG. 3). The unbalanced vibration is eliminated by the component of the signal Fy. Further, vibration is performed by the component of the X-axis direction excitation signal Ex included in the current supplied to the electromagnet 12X and the component of the Y-axis direction excitation signal Ey included in the current supplied to the electromagnet 12Y.

  With this configuration, when the vibration characteristic measuring apparatus 1 (see FIG. 1A) measures the response characteristics of the rotating body provided in the multistage centrifugal compressor 50 (see FIG. 1A), the vibration characteristics of the rotating body are not detected. Balance vibration can be eliminated. As a result, the allowable range of the amplitude of forced vibration due to vibration can be expanded, and the X displacement signal output by the displacement sensor 13 (X displacement sensor 13X (see FIG. 3), Y displacement sensor 13Y (see FIG. 3)). The SN ratio of Mx and Y displacement signal My can be improved. And the vibration response analyzer 9 (refer FIG. 3) can acquire the high quality data regarding the displacement of a X-axis direction, and the high quality data regarding the displacement of a Y-axis direction.

  Furthermore, since the quality of data to be acquired is high and the response characteristics of the rotating body can be evaluated with a small number of data, the time required for data acquisition can be shortened. As a result, man-hours required for data acquisition can be reduced, and energy consumption can be reduced.

Note that, as the excitation signals Ex and Ey, in addition to the above-described sine wave signal, a random signal, a pulse signal, or the like can be considered.
Even when the vibration response analyzing device 9 generates a signal other than a sine wave signal as a vibration signal, the vibration signal component (first direction vibration component, second direction vibration component) is included in the vibration signal component. What is necessary is just to set it as the structure which supplies the electric current which amplified the rotating body control signal which added (cosine wave component, sine wave component) with the current amplifier 11 (refer FIG. 3) to the magnetic bearing 12 (refer FIG. 3).

  In addition, in order to evaluate the stability of the rotating body, there is also a method of identifying system parameters by analyzing the vibration waveform of the rotating body. For example, the rotating body is vibrated with an excitation signal including a sine wave component of a frequency that causes the vibration of the natural frequency in the rotating body, and the excitation signal is instantaneously cut off when the rotating body is in a resonance state. System parameters can be identified by the free vibration waveform of the time (for example, refer to “System identification for control by MATLAB (Shuichi Adachi, Tokyo Denki University Press)”) .

  In the case of the method for identifying the system parameters as described above, the rotating body control signal obtained by adding the oscillation signal to the excitation signal for generating the vibration of the natural frequency in the rotating body is amplified by the current amplifier 11 (see FIG. 3). What is necessary is just to set it as the structure which supplies an electric current to the magnetic bearing 12 (refer FIG. 3). Furthermore, if the configuration is such that the current obtained by amplifying the oscillation signals Fx and Fy by the current amplifier 11 is supplied to the magnetic bearing 12 while the rotating body is freely vibrating after the excitation signal is cut off, the displacement sensor 13 (FIG. 3) can measure the displacement of a rotating body that is freely vibrating without being affected by unbalanced vibration.

As an example of a design change of the vibration characteristic measuring apparatus 1, for example, as shown in FIG. 6, an excitation control having an excitation signal circuit breaker 10 that blocks output of the addition signals ADDx and ADDy output from the adder 7a. The structure provided with the apparatus 7 may be sufficient.
The vibration signal breaker 10 receives the X displacement signal Mx output from the X displacement sensor 13X and the Y displacement signal My output from the Y displacement sensor 13Y.
The vibration signal breaker 10 is at least one of the displacement in the X-axis direction of the rotating body calculated based on the X-displacement signal Mx or the displacement in the Y-axis direction of the rotating body calculated based on the Y-displacement signal My. Is configured to block the output of the addition signals ADDx and ADDy when the value exceeds a predetermined threshold.

  According to this configuration, for example, when the displacement in the X-axis direction or the displacement in the Y-axis direction exceeds a predetermined threshold due to the excitation by the components of the excitation signals Ex and Ey of the addition signals ADDx and ADDy, that is, the rotation When the body amplitude exceeds the allowable value, the supply of the current obtained by amplifying the addition signals ADDx and ADDy by the current amplifier 11 to the magnetic bearing 12 is cut off. Therefore, it is possible to converge vibration with an amplitude exceeding the allowable value generated in the rotating body, and for example, it is possible to prevent the seal mechanism 55 (see FIG. 1A) from being damaged.

Although not shown, if the vibration signal breaker 10 is arranged between the vibration response analyzer 9 and the adder 7a, the vibration response when the amplitude of the rotating body exceeds the allowable value. The input of the excitation signals Ex and Ey output from the analyzer 9 to the adder 7a can be cut off. Therefore, only the oscillation signals Fx and Fy are output from the vibration control device 7, and the current obtained by amplifying the oscillation signals Fx and Fy by the current amplifier 11 is supplied to the magnetic bearing 12.
According to this configuration, it is possible to more quickly converge the vibration with the amplitude exceeding the allowable value generated in the rotating body.

DESCRIPTION OF SYMBOLS 1 Vibration characteristic measuring apparatus 7 Excitation control apparatus 8 Balance signal generator 9 Excitation response analyzer 10 Excitation signal breaker 11 Current amplifier (current supply apparatus)
12 Magnetic bearing 13 Displacement sensor (measuring device)
50 Multistage centrifugal compressor (rotary machine)
51 Rotating shaft (Rotating body)
52a, 52b, 52c Bearing member 53 Centrifugal impeller (rotating body)
54 Housing (stationary body)
55 Seal mechanism ADDx, ADDy addition signal (rotary body control signal)
Ex, Ey Excitation signal (Excitation control signal)
Fx, Fy oscillation signal Fz vibration cancellation signal

Claims (3)

A magnetic bearing that supports the rotating body of the rotating machine in a non-contact manner;
A measuring device for measuring an amplitude when the rotating body vibrates;
A current supply device for supplying a current to the magnetic bearing;
An excitation control signal for controlling the magnetic bearing to vibrate the rotating body is output, and the vibration of the rotating body is applied to the excitation control signal based on the amplitude measured by the measuring device. A vibration control device for measuring a response characteristic to a vibration control signal,
The vibration control device has a vibration response analysis device and a balancing signal generator, and when measuring the response characteristics,
The balance signal generator generates a vibration cancellation signal for canceling the unbalanced vibration generated when the rotating body rotates by the magnetic bearing, and cancels the unbalanced vibration. A rotating body control signal added to the excitation control signal is output, and the rotating body is vibrated by generating a forced vibration having a maximum amplitude based on an allowable value based on the state without the unbalanced vibration,
A vibration characteristic measuring apparatus, wherein the response characteristic of the rotating body being vibrated is measured by the vibration response analyzer. The rotating machine is a multi-stage centrifugal compressor,
2. The vibration characteristic measurement according to claim 1, wherein the allowable value is provided so that a seal mechanism provided in a stationary body of the multistage centrifugal compressor and the rotating body do not contact with each other due to the unbalanced vibration. apparatus. A magnetic bearing that supports the rotating body of the rotating machine in a non-contact manner;
A measuring device for measuring an amplitude when the rotating body vibrates;
An excitation response analyzer for outputting an excitation control signal for controlling the magnetic bearing so as to vibrate the rotating body, and a vibration canceling signal for eliminating unbalanced vibration that occurs when the rotating body rotates. And a vibration control device that includes a balance signal generator and a vibration control device that measures a response characteristic of the vibration of the rotating body to the vibration control signal based on the amplitude measured by the measurement device. A vibration characteristic measuring method in
When measuring the response characteristic, generating the vibration cancellation signal in the balancing signal generator to eliminate the unbalanced vibration;
The vibration cancellation signal is added to the vibration control signal to generate a forced vibration having a maximum amplitude based on a state where there is no unbalanced vibration, and the rotating body is vibrated to be excited. Measuring the response characteristics of the rotating body being vibrated with the vibration response analyzer;
A vibration characteristic measuring method characterized by comprising: