JP2585953B2 - Open blade thickness monitor for rotating machinery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for monitoring the thickness of an open blade of a rotating machine, which monitors the thickness of the open blade of the rotating machine in an operating state.

[0002]

2. Description of the Related Art In a conventional rotating machine, a vibration sensor is attached to a bearing housing portion, and the quality of the rotating machine is estimated and determined from the magnitude of vibration amplitude, vibration speed, vibration acceleration, and the like. . Alternatively, two gap sensors are provided in two directions perpendicular to each other in a plane perpendicular to the axis close to the rotation axis, and the state of the rotary machine is estimated based on a change in the distance between the rotation axis and the gap sensor. Have been.

[0003]

In the above-mentioned conventional method for judging the state of the rotating machine, the behavior of the rotating body due to hydrodynamic or mechanical causes occurring inside the rotating machine is externally grasped. When an abnormal vibration occurs, the investigation of the cause does not go beyond estimation. The rotating machine itself is under the floor, such as a vertical pump, and when vibration is detected from the rotary shaft above the floor, different vibrations occur depending on the installation state of the vertical pump. It is difficult to determine the cause because of the attenuated state.

However, in the conventional apparatus for measuring vibrations and the like, it is impossible to detect a decrease in pump performance due to wear of the blades. Further, even if abnormal vibration occurs in the rotating machine due to wear of the blades, the cause cannot be specified. For this reason, there is no other way to know the state of the impeller, the blades, etc., except to stop the operation, disassemble, and directly check it visually.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides an open blade thickness monitoring device for a rotating machine which directly measures the thickness of an open blade in an operating state. The purpose is to do.

[0006]

In order to achieve the above object, an apparatus for monitoring the thickness of an open type blade of a rotary machine according to the present invention is provided with the open type blade at a position close to a rotating surface of the open type blade of the rotary machine. A gap sensor disposed toward the blade, means for measuring a time width of an output signal output from the gap sensor when the open type blade passes in front of the gap sensor, Thickness calculating means for calculating the thickness of the open type blade from the passing speed of the die blade,
It is comprised including.

Also, a gap sensor is provided at the position close to the rotating surface of the open type blade of the rotary machine toward the open type blade, and an A / D for sampling and A / D converting an output signal of the gap sensor. Conversion means and this A /
Differentiating means for numerically differentiating the discrete amount data output from the D converting means; and discrete amount data sampled from the differential data output from the differentiating means while the output signal of the gap sensor is changed by the open-type blade. And a thickness calculating means for calculating the thickness of the open-type blade from the sampled number and the passing speed of the open-type blade.

Also, a gap sensor arranged toward the open blade at a position close to the rotating surface of the open blade of the rotary machine, and an A / D for sampling and A / D converting an output signal of the gap sensor. Conversion means and this A /
Comparison means for comparing the discrete amount data output from the D-conversion means with a reference value; timer means for measuring a time width during which the discrete amount data exceeds the reference value; Thickness calculating means for calculating the thickness of the open type blade from the passing speed of the type blade.

The difference between the actual thickness of the open type blade and the thickness calculated by the thickness calculating means is measured in advance, and a correction value corresponding to the difference is calculated from the thickness calculated by the thickness calculating means. May be provided by providing a correction means for correcting.

Further, the gap sensor may be provided on a casing of an impeller, and a sensing surface of the gap sensor facing the open type blade may be covered with a nonmagnetic ceramic.

[0011]

According to a first aspect of the present invention, there is provided an apparatus for monitoring the thickness of an open blade of a rotary machine, wherein the open blade is directly opened based on a time width of an output signal output from a gap sensor and a passage speed of the open blade. The measurement result according to the thickness of the mold blade can be calculated.

According to a second aspect of the present invention, there is provided an apparatus for monitoring the thickness of an open blade of a rotary machine, wherein the open blade crosses in front of a gap sensor with a time width corresponding to the thickness of the open blade. By differentiating the output signal output from the gap sensor, the start point and the end point of the change of the output signal can be specified, and the time width during which the output signal is output can be specified from the number of discrete data sampled during that time. Therefore, a measurement result corresponding to the thickness of the open blade can be obtained from the time width and the rotation speed of the open blade.

According to the third aspect of the present invention, the output signal is easily output by comparing the output signal output from the gap sensor with a reference value. Can specify the time span during Then, from this time width, a time width corresponding to the time when the open blade crosses in front of the gap sensor can be specified. Therefore, a measurement result corresponding to the thickness of the open blade can be obtained from the time width and the rotation speed of the open blade.

According to a fourth aspect of the present invention, the difference between the actual thickness of the open type blade and the thickness calculated by the thickness calculating means is measured in advance. Since the difference is corrected by the correction means, the accuracy of the measured thickness of the open blade is improved.

Furthermore, in the apparatus for monitoring the thickness of an open type blade of a rotary machine according to the present invention, the sensing surface of the gap sensor facing the open type blade is covered with a non-magnetic ceramic material. The sensitive surface of the gap sensor can be protected from fluid wear without affecting the output signal from the gap sensor.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block circuit diagram of one embodiment of an open blade thickness monitoring device for a rotating machine according to the present invention;
FIG. 2A is a waveform diagram of an output signal of the gap sensor, FIG. 2B is a waveform diagram based on a differential value thereof, FIG. 3A is a waveform diagram based on discrete amount data, FIG.
FIG. 4B is a waveform diagram based on a numerical differential value at each point of the discrete amount data, and FIG. 4 is a flowchart illustrating the operation of the open blade thickness monitoring device of the rotating machine according to the present invention;
FIG. 5 is a cross-sectional view of a main part in which the sensing surface of the gap sensor is covered with ceramics.

First, in FIG. 1, a small gap g (for example, 1 mm) is provided on the rotating surface of an open type blade 10 of a rotary machine such as a vertical shaft pump or a mixed flow pump, and a gap sensor 12 is directed toward the open type blade 10. Will be arranged. The output signal of the gap sensor 12 is appropriately amplified by the amplifying unit 14 and provided to the A / D converting unit 16. In the A / D conversion means 16, the output signal is sampled at an appropriate sampling period (for example, 96 μs).
Is converted. Then, the A / D-converted discrete amount data is given to the differentiating means 18 and the display means 20, respectively. In the differentiating means 18, the discrete amount data is numerically differentiated by the forward difference method, the central difference method, the Lagrange interpolation method, or the like, and the numerically differentiated value is provided to the sampling number calculating means 22 and the display means 20. In the sampling number calculation means 22, the output signal output from the gap sensor 12 is calculated based on the numerical differential value data.
The number of discrete amount data sampled while changing with the passage of 0 is calculated, and the calculation result is given to the thickness calculating means 24. The sampling cycle, the rotation speed of the open blade 10 and the radius at which the gap sensor 12 is provided are given to the thickness calculating means 24 in advance.
The passing speed of the open blade 10 is calculated, and the thickness of the open blade 10 is calculated from the number of samplings. The calculated thickness is further corrected by the correction unit 26 and is provided to the display unit 20 as data corresponding to the thickness. This display means 20 displays the waveform of the output signal output from the gap sensor 12 as shown in FIG.
The waveform of the differential value obtained by differentiating the waveform of the output signal as in (b) and the thickness of the open-type blade 10 corrected by the correction means 26 are appropriately displayed.

The A / D converting means 16, the differentiating means 18, the sampling number calculating means 22, the thickness calculating means 24 and the correcting means 26 are processed by a computer 28 as software. Note that the A / D conversion means 16 may be provided outside the computer 28.

The operation of the apparatus for monitoring the thickness of an open blade of a rotary machine according to the present invention will be described below with reference to FIG. First, the output signal of the gap sensor 12 is sampled to take in data (step), and then A / D converted to output discrete amount data (step). Then, the discrete amount data is numerically differentiated (step).

The discrete amount data output from the A / D converter 16 is shown in FIG. 3 (a). Then, this discrete amount data is converted into, for example, the Lagrange interpolation 5
If the point method is used to perform numerical differentiation, the time point k at which the open type blade 10 approaches the gap sensor 12 and the gap sensor 12 starts to sense and the output signal starts to change in the positive direction.
_{In 1} (0), the differential value becomes a negative value as shown in FIG. Further, the open type blade 10 is used as the gap sensor 1.
At the time point k ₂ (0) at which the gap sensor 12 is no longer perceived from the distance 2, the differential value becomes a positive value as shown in FIG. 3B.

Therefore, the negative value at the time point of k ₁ (0) and the positive value at the time point of k ₂ (0) are detected by the sampling number calculating means 22, that is, the starting point and the ending point of the change of the output signal are detected. From the number of discrete data sampled between k ₁ (0) and k ₂ (0), the time width during which the gap sensor 12 senses the open blade 10 is calculated as the number of samples. (Step).

The speed of the open blade 10 passing through the gap sensor 12 can be calculated from the rotation speed of the open blade 10 and the radius at which the gap sensor 12 is disposed with respect to the open blade 10. Also, the time width between them can be calculated from the number of samplings and the sampling period. Therefore, the thickness of the open blade 10 is calculated by the thickness calculating means 24 from the number of samples obtained by the sampling number calculating means 22 (step).

The thickness calculated by the thickness calculating means 24 may include the following errors. That is, when the open-type blade 10 approaches the gap sensor 12, the open-type blade 10 senses this before the gap-type sensor 12 faces the gap sensor 12, and the output signal starts to change in the positive direction. If the open blade 10 continues to be sensed until the output signal returns to zero after the open type blade 10 has already passed through the gap sensor 12 when the member 10 moves away from the gap sensor 12, the thickness is calculated by the thickness calculating means 24. The thickness will be larger than it actually is. Conversely, if the output signal changes with a delay when approaching, and returns to zero while still facing when leaving, the thickness by the thickness calculating means 24 is smaller than the actual one. Becomes According to experiments performed by the inventors, it has been found that the degree to which the gap sensor 12 senses is affected by the size of the gap g, the material and shape of the open blade 10 and the like. And
These factors are constant depending on the type of the open blade 10.

Therefore, the actual thickness of the open type blade 10 and
A difference from the thickness calculated by the thickness calculating means 24 is measured in advance, a correction value is set in accordance with the difference, and the thickness calculated by the thickness calculating means 24 is corrected by the correcting means 26 using the correction value. Thus, the accurate thickness of the open blade 10 is calculated (step).

Finally, the display means 2 determines the exact thickness of the open type blade 10 together with the output signal and the waveform of the differential value.
0 is displayed (step), and the operation ends.

If the type of the open blade 10 and the size of the gap g are appropriately set, the thickness calculating means 2
The thickness calculated in 4 can be made to match the actual thickness of the open blade 10. In such a case, the correction unit 26 in FIG. 1 may be omitted, and the step in FIG. 4 may be omitted. When the correction value changes in accordance with the rotation speed of the open blade 10, a data table or a relational expression of the rotation speed versus the correction value is obtained in advance, and the correction value in the correction means 26 is set to the rotation speed of the open blade 10. It may be corrected according to.

Further, in one embodiment of the apparatus for monitoring the thickness of an open blade of a rotary machine according to the present invention, the gap sensor 1 is provided.
2 to prevent abrasion by the fluid of the sensing surface 12a to prevent the gap g
In order to maintain the gap, as shown in FIG.
The second sensing surface 12a is covered with a nonmagnetic ceramic 30. The gap sensor 12 having the sensing surface 12 a covered with the ceramic 30 is fitted in a hole formed in the casing 32 and arranged so as to face the open type blade 10. The gap sensor 12 is housed in a retainer 34, and the gap sensor 12 is integrated with the ceramics 30 and the retainer 34 by filling with an epoxy resin 36. Further, an O-ring 38 is provided between the integrated retainer 34 and the casing 32 to form a watertight structure.

Next, another embodiment of the present invention will be described with reference to FIGS. FIG. 6 is a block circuit diagram of another embodiment of the open blade thickness monitoring device for a rotary machine according to the present invention, and FIG. 7 is a diagram for explaining the operation of the comparing means in FIG. 6, the same or equivalent circuit blocks as those in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted.

The difference between the apparatus shown in FIG. 6 and the apparatus shown in FIG.
1 in that a comparing means 40 and a time measuring means 42 are provided instead of the differentiating means 18 and the sampling number calculating means 22 in FIG. That is, the discrete amount data sampled and A / D converted by the A / D conversion means 16 is given to the comparison means 40 and compared with the reference value Vref as shown in FIG. The time width t during which the signal output of the A / D conversion means 16 exceeds the reference value Vref is determined by the time measurement means 42.
And is given to the thickness calculating means 24. The thickness calculating means 24 is provided with data capable of calculating the passing speed of the open-type blade 10, and the thickness of the open-type blade 10 is calculated from the time width t provided by the timer 42.
The display unit 20 appropriately displays the waveform of the output signal of the gap sensor 12 and the corrected thickness of the open blade 10.

The A / D converting means 16, the comparing means 40, the time measuring means 42, the thickness calculating means 24 and the correcting means 26
Are processed by software by the computer 28.

In each of the above embodiments, the thickness of the open blade 10 at the present time has been described as being calculated.
The thickness of the open blade 10 may be determined by comparing the initial value with the current value.

In the above-described embodiment, the output signal of the gap sensor 12 is converted into an A / D signal by the A / D conversion means 16 in order to perform digital processing by the computer 28.
Although the D / D conversion is performed, if the analog processing can be performed, the A / D conversion means 16 is of course unnecessary. Further, instead of the software processing of the computer 28, some or all of the processing may be performed by hardware processing. Further, the gap sensor 12 can also be used as one of two gap sensors provided at a relative position orthogonal to or opposed to the rotating body for displaying an orbit trajectory (Lissajous figure). .

[0033]

As described above, the open-type blade thickness monitoring device of the rotating machine according to the present invention is constituted, and therefore, has the following special effects.

In the apparatus for monitoring the thickness of an open blade of a rotary machine according to the first aspect, a measurement result corresponding to the thickness of the open blade in an operating state can be directly obtained. It is possible to determine the wear of the open type blade with extremely high accuracy as compared to estimating and determining the cause from the above. In addition, from the degree of wear of the open type blade, it is possible to infer performance deterioration of the pump and the like.

In the apparatus for monitoring the thickness of an open type blade of a rotary machine according to the second and third aspects, the output signal of the gap sensor is processed as a digital signal. The thickness can be calculated, and the wear state of the open blade can be monitored in real time while operating.

According to the fourth aspect of the present invention, the thickness of the open-type blade can be measured and calculated with high accuracy, and the open-type blade thickness of the open-type blade can be reliably measured. The wear condition can be monitored.

Furthermore, in the apparatus for monitoring the thickness of an open blade of a rotary machine according to the fifth aspect, the gap sensor is covered with ceramics so that the gap sensor is not worn by the fluid. The gap between the open blade and the gap sensor can be kept constant,
As a result, the measurement accuracy of the thickness of the open type blade can be maintained for many months, which is extremely useful in practical use.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of one embodiment of a device for monitoring the thickness of an open blade of a rotating machine according to the present invention.

2A is a waveform diagram of an output signal of a gap sensor, and FIG. 2B is a waveform diagram of a differential value thereof.

FIG. 3A is a waveform diagram based on discrete amount data,
(B) is a waveform diagram based on a numerical differential value at each point of the discrete amount data.

FIG. 4 is a flowchart illustrating the operation of the open blade thickness monitoring device of the rotary machine according to the present invention.

FIG. 5 is a sectional view of a main part in which a sensing surface of a gap sensor is covered with ceramics.

FIG. 6 is a block circuit diagram of another embodiment of the open blade thickness monitoring device for the rotary machine according to the present invention.

FIG. 7 is a diagram for explaining the operation of the comparing means in FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Open type blade 12 Gap sensor 12a Sensing surface 16 A / D conversion means 18 Differentiation means 22 Sampling number calculation means 24 Thickness calculation means 26 Correction means 30 Ceramics 40 Comparison means 42 Timing means

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hiroshi Masushima 10-24, Midoricho, Mishima-shi, Shizuoka Prefecture Inside the Mishima Works of Machinery Works, Ltd. (72) Inventor Osamu Kota 10-24, Midoricho, Mishima-shi, Shizuoka Stock (56) References JP-A-3-48110 (JP, A) JP-A-61-20805 (JP, A) JP-A-63-135812 (JP, A) JP-A Sho 58-75007 (JP, A) JP-A-58-37503 (JP, A) JP-A-51-64948 (JP, A) Jpn.

Claims (5)

(57) [Claims] 1. A gap sensor disposed at a position close to a rotation surface of an open blade of a rotary machine and facing the open blade, and the gap when the open blade passes in front of the gap sensor. Means for measuring the time width of the output signal output from the sensor, and thickness calculating means for calculating the thickness of the open blade from the time width and the passing speed of the open blade. An apparatus for monitoring the thickness of an open blade of a rotating machine. 2. A gap sensor disposed close to a rotating surface of an open-type blade of a rotating machine toward the open-type blade, and an A / D for sampling and A / D-converting an output signal of the gap sensor. Converting means; differentiating means for numerically differentiating the discrete amount data output from the A / D converting means; and, while the output signal of the gap sensor is changed by the open blade from the differential data output from the differentiating means. Sampling number calculating means for calculating the number of discrete amounts of data sampled in, and thickness calculating means for calculating the thickness of the open type blade from the sampled number and the passing speed of the open type blade. An open-type blade thickness monitoring device for a rotary machine, comprising: 3. A gap sensor disposed close to a rotating surface of an open type blade of a rotary machine toward said open type blade, and an A / D for sampling and A / D converting an output signal of the gap sensor. Converting means; comparing means for comparing the discrete amount data output from the A / D converting means with a reference value; timing means for measuring a time width during which the discrete amount data exceeds the reference value; Thickness calculating means for calculating the thickness of the open-type blade from the time width by means and the passage speed of the open-type blade. . 4. The open blade thickness monitoring device for a rotary machine according to claim 1, wherein the difference between the actual thickness of the open blade and the thickness calculated by the thickness calculating means is determined. An apparatus for monitoring the thickness of an open-type blade of a rotary machine, comprising: a correction unit that measures in advance and corrects a correction value according to the difference from the thickness calculated by the thickness calculation unit. 5. The open blade thickness monitoring device for a rotary machine according to claim 1, wherein the gap sensor is disposed on a casing of an impeller, and the gap sensor is attached to the open blade of the gap sensor. An open-type blade thickness monitoring device for a rotary machine, wherein an opposing sensing surface is covered with a nonmagnetic ceramic.