JP3117865B2 - Diagnosis method for rotating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for diagnosing abnormalities in a rotating device such as a motor based on the acceleration, speed, and displacement of the vibration.

[0002]

2. Description of the Related Art For example, in a device having a rotating part such as a motor, abrasion or damage (for example, damage to a bearing) due to a high load may occur with use, and in the worst case, the device is immediately stopped. I have to do it. In FIG.
The horizontal axis indicates the vibration frequency, and the vertical axis indicates the acceleration, which is the vibration value.A conceptual diagram of the frequency distribution of the mechanical vibration is shown. As is clear from this figure, as a means for monitoring the presence or absence of abnormality in the rotating device, Conventionally, a method based on vibration analysis has been used.

In this method, as is apparent from FIG. 5, vibration of a rotating device is detected by an acceleration sensor, and the vibration value measured when the device is installed in a normal state is compared. An abnormality is determined when the value is equal to or more than a certain value. When performing abnormality monitoring, an alarm is generated based on the abnormality determination result, and further, the device is automatically stopped.

[0004] Further, there is an idea of a relative judgment criterion.
The relative criterion is a method in which the same part is periodically measured and compared in chronological order, and as an initial value of a normal value, a determination is made by seeing how many times the value has increased.

In low-frequency vibrations, if the vibration value changes by 4 dB based on past experience values or human senses, it is perceived as having changed as a vibration sensation.
In many cases, the standard is created with the caution area when the value is approximately doubled and the abnormal value when the value is approximately four times. At high frequencies,
From the results of the forced deterioration test of the mechanical element, there is an example in which a caution area is set at about three times the initial value and an abnormal area is set at about six times the initial value. FIG. 6 shows an example of such a relative determination criterion.

[0006]

However, in the above-mentioned prior art, the detection of vibration is performed at a fixed rotation speed. However, when the rotation speed changes, the vibration value of the device changes with the rotation change even in the same deterioration state. For this reason, under operating conditions in which the number of revolutions of the device changes, a situation occurs in which an alarm is issued even when there is no abnormality, so that trend management cannot be performed.

[0007] Further, since the vibration value greatly varies with the change in the number of revolutions, when the measurement is performed under the condition of a constant number of revolutions, the number of measurement opportunities becomes extremely small, which also makes it difficult to manage the tendency. Was.

[0008] For the above reasons, the vibration analysis method is limited in applicable equipment and has low diagnostic accuracy, so that its practicality is poor.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for diagnosing abnormalities of a rotating device, which expands the scope of application of abnormalities diagnosis by a vibration analysis method and enables high-precision diagnosis.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an equation in which the relationship between the normal rotation speed of a rotating device and the vibration value of the rotating device is approximated by a quadratic or cubic function. Is used to correct a vibration value at an arbitrary rotation speed to a vibration value at a reference rotation speed, and an abnormality is determined based on the correction value.

[0011]

[0012]

According to the above-described means, an equation is created by approximating the relative relationship between the rotation speed and the vibration value by the least squares method, and based on this, the vibration value at an arbitrary rotation speed is calculated at the reference rotation speed. The vibration value is corrected, and when the correction value exceeds a threshold value, it is determined that the vibration value is abnormal.

[0013] Thus, even for a rotating device having a rotation fluctuation, a vibration analysis method can be used, and a highly accurate abnormality diagnosis can be performed.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a flowchart illustrating a method for diagnosing an abnormality of a rotating device according to the present invention. FIG. 2 is a block diagram showing an abnormality diagnosis device according to the present invention. FIG. 3 is a rotation speed-vibration level characteristic diagram for explaining the correction processing according to the present invention. In FIG. 1, the steps of the flowchart are represented by “ST”.

[0016] As shown in FIG.
An input interface 203 connected to a bus 202, a ROM (read only memory) 204 storing programs and set values, and a measured value are temporarily stored around a U (central processing unit) 201. RAM
(Random access memory) 205 and a computer portion composed of an output interface 206 are mainly constituted.

Further, the input interface 203 is connected to a vibration sensor 207 for measuring acceleration, velocity, and displacement as vibration values, and the output interface 206 is connected to an electro-acoustic conversion device such as a buzzer and a drive circuit for driving the device. Is connected.
The vibration sensor 207 is installed indirectly or directly on a rotating device (in this embodiment, a motor), and measures vibration accompanying rotation in the form of acceleration, velocity, or displacement. And CP
U201 performs the process shown in FIG.

First, the relationship between the rotational speed of the rotating device and the vibration value immediately after installation is measured, and this is stored and stored as an initial value (ST101). Next, the vibration value during operation (that is, at present) is measured by the vibration sensor 207, the CPU 201 reads the measured value via the input interface 203, and stores it in the RAM 205 via the bus 202 (ST102).

If the number of revolutions of the operating device does not change for a certain time (or a certain period) (ST103), the process proceeds to step 105, and there is a change in the number of rotations for a certain time (or a certain period). In the case, the measured value in step 102 and the data stored in the ROM 204 (the average value obtained by performing the data extraction processing on the vibration data and the rotation data)
(ST104). In this correction calculation, the correlation between the rotation speed n and the vibration value V is approximated by the least squares method to obtain the expression S. Details of the correction processing will be described with reference to FIG.

For example, if the vibration value V _n at a certain rotation speed n shown in FIG. 3 is corrected to a vibration value V _s at a reference rotation speed n _s , trend management becomes possible. The formula used for this is
Secondary or tertiary function is used, represented by the following formula (free
And, S _n is a function, A, B, C are known coefficients). (Secondary expression) _Sn = A × (n−B) ² + C (1) (cubic expression) _Sn = A × (n−B) ³ + C (2) Further, the corrected vibration value V _s Is determined as follows.

[0021] _{(quadratic) V s = A '× (} n s -B) 2 + C ··· (3) ( _{cubic) V s = A' × (} n s -B) 3 + C ··· ( 4) where A '= (V _n -C) / (n-B) ^{2 in} equation (3) A' = (V _n -C) / (n-B) ³ _ns = reference in equation (4) Number of rotations n = number of rotations measured in step 102 Also, the coefficients B and C of the formula (1) or (2)
Are used as the B and C values shown in equation (4). A program for performing such an operation is incorporated in the ROM 204, and its execution is performed by the CPU 201. It is determined whether or not the corrected vibration value Vs has _exceeded a preset threshold (ST105).
6 to drive the alarm 208 to issue a warning (ST
106). Also, when it is determined in step 103 that there is no change in rotation, it is determined whether or not the vibration value exceeds a threshold value.

[0022]

[0023]

[0024]

Since the present invention is constituted as described above, the following effects can be obtained.

In the method of diagnosing abnormality of a rotating device according to the first aspect of the present invention, an arbitrary rotation is determined by using an equation approximated by a quadratic or cubic function to a relationship between a rotating speed of the rotating device in a normal state and a vibration value of the rotating device. The vibration value in the number is corrected to the vibration value of the reference rotation speed, and the abnormal value is determined based on this correction value. Diagnosis of abnormalities becomes possible.

[0026]

[0027]

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a method for diagnosing abnormality of a rotating device according to the present invention.

FIG. 2 is a block diagram showing an abnormality diagnosis device according to the present invention.

FIG. 3 is a rotation speed-vibration level characteristic diagram for explaining a correction process according to the present invention.

FIG. 4 is a diagram showing a relationship between a vibration value and a vibration frequency in a rotating device.

FIG. 5 is a diagram showing an implementation process of state-based maintenance in a rotating device.

FIG. 6 is a diagram illustrating an example of a relative determination criterion.

[Explanation of symbols]

 201 CPU 202 Bus 203 Input interface 204 ROM 205 RAM 206 Output interface 207 Vibration sensor 208 Alarm

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01H 17/00 G01M 19/00

Claims (1)

(57) [Claims] [Claim 1] The relationship between the vibration value S _n of the rotational speed n and the rotating device in the normal of the rotating device is approximated by a secondary or tertiary function following (1) or (2) of the coefficients B, C value the,
Using the B and C values shown in the following equation (3) or (4) ,
Correcting the vibration value V _n at an arbitrary rotational speed n to the vibration value V _s of the following (3) or (4) the reference number of revolutions in the expression n _s, to determine an abnormality by the correction value exceeds the threshold A method for diagnosing abnormality of a rotating device. (Secondary expression) _Sn = A × (n−B) ² + C (1) (Tertiary expression) _Sn = A × (n−B) ³ + C (2) (Secondary expression) _{V s = A '× (n} s -B) 2 + C ··· (3) ( _{cubic) V s = A' × (} n s -B) 3 + C ··· (4) However, A, B, C is a known coefficient; A ′ = (V _n −C) / (n−B) ^{2 in} equation (3); A ′ = (V _n −C) / (n−B) ^{3 in} equation (4)