JP2001349466A - Valve seat deterioration detecting device for valve driven by electric actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a valve seat deterioration detecting device in which deterioration of a valve seat with the lapse of time can be recognized at favorable reproducibility without using a strain gauge or dismantling piping or valves. SOLUTION: For detecting deterioration of a valve seat in a valve driven by an electric actuator, change of input valves with the lapse of time detected by a torque detecting device to detect the input valves of the electric actuator for a valve opening is measured, thereby the deterioration of the valve seat with the lapse of time is recognized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting deterioration of a valve seat of a valve driven by an electric actuator, and more particularly to detecting deterioration of a valve seat without removing a valve case or a pipe. The present invention relates to a valve seat deterioration detection device having high reproducibility of values.

[0002]

2. Description of the Related Art Generally, in butterfly valves, ball valves, and other valves driven by an electric actuator, an output shaft of the electric actuator is rotated to rotate a valve directly connected to a valve stem. In order to enhance the sealing performance when the valve is closed, a material such as elastic rubber or resin is used for the valve seat against which the valve body is pressed.

The force for pressing the valve body against the valve seat is generated by torque applied to the output shaft of the electric actuator.

As described above, the sealing performance of the valve is achieved by pressing the valve body against the valve seat.
A valve seat made of elastic rubber or resin deteriorates with time.

[0005] The deterioration of the sealing performance due to the deterioration of the valve seat is avoided by replacing the seat. However, in order to reduce the maintenance work, the valve case is not disassembled and the piping is not detached. It is desirable to be able to observe the state of deterioration of the valve seat from outside the valve.

[0006]

As a method meeting the above demands, a method of measuring the driving torque of a valve and estimating the degree of deterioration of the valve seat from a change with time has conventionally been adopted. This is because the driving force of the valve changes depending on the contact state between the valve body and the valve seat, and such a contact state depends on the degree of deterioration of the valve seat which changes with time.

As a method of measuring the drive torque applied to the valve drive shaft, a strain gauge is conventionally attached to a valve rod on which the valve drive torque acts directly, and the amount of strain is converted into an electric signal and detected. That is being done.

Although such a method can measure the valve driving torque without removing the valve body and the piping, it is very useful for reducing the maintenance work.
Strain gauges are vulnerable to external shocks, and the measured values are greatly affected by the temperature conditions in which they are used. Therefore, measurement of valve torque under actual use conditions has been impossible in terms of reproducibility. In addition, there is a problem that a rise in price cannot be suppressed because a strain gauge is required.

[0009]

SUMMARY OF THE INVENTION The present invention is provided to solve the above-mentioned problems. That is, according to the present invention, in a valve seat deterioration detecting device for detecting deterioration of a valve seat of a valve driven by an electric actuator, an input value for a valve opening of the electric actuator is detected. The present invention is configured as a valve seat deterioration detecting device for a valve driven by an electric actuator, which is provided with a torque detecting device and measures a temporal change of an input value detected by the torque detecting device.

According to a second aspect of the present invention, in the valve seat deterioration detecting device for a valve driven by the electric actuator according to the first aspect, the change with time of the input value is displayed on a monitor. I have.

[0011] The invention according to claim 3 is based on claim 1.
The device for detecting deterioration of a valve seat of a valve driven by an electric actuator according to the present invention includes a data table which is measured in advance with respect to a change with time of an input value and a degree of deterioration of a valve seat, and when the change with time of the input value is detected. The degree of deterioration of the valve seat is obtained from the data table and is displayed.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
Embodiments embodying the present invention will be described for the understanding of the present invention. Here, FIG. 1 is a block diagram of a deterioration detection device according to one embodiment of the present invention, and FIG. 2 is a graph showing a relationship between a valve opening and a drive voltage (input value) in the above embodiment. Tables 1 and 2 show the relationship between the drive voltage that fluctuates according to the change in the generated torque between the case of the AC motor and the case of the DC motor, respectively. Is set.

In FIG. 1, in a valve control circuit surrounded by a dotted line, a set value (input signal) e input from the outside to a motor drive circuit passes through a set value input circuit to a first A / D.
It enters a converter, where it is converted to a digital signal and input to a decision circuit.

An operation angle feedback signal generator connected to the output shaft of the motor m converts the rotation angle of the motor m into an electric signal. The angle signal output from the operating angle feedback signal generator is input to a feedback input circuit, further converted to a digital signal by a second A / D converter, and then input to a determination circuit.

The determination circuit compares the set value from the first A / D converter with the feedback value from the second A / D converter, and outputs a signal corresponding to the difference to the motor drive. Output to the circuit. The motor m is driven by a signal corresponding to the difference. Specifically, the signals described in Table 1 or Table 2 are used.

[Table 1] Table 1 is a table showing the relationship between the drive voltage and the generated torque when the motor m is an AC motor. Pattern numbers are assigned in ascending order of generated torque.

[Table 2] Table 2 is a table in the case where the motor m is a direct current. These tables are used depending on the type of the motor.

In the case of an AC motor, the state of pattern number 2 where the drive voltage is the lowest produces the smallest torque. Therefore, when the difference signal from the first A / D converter and the second A / D converter is very small, that is, when the difference between the target value and the actually measured value is small, the motor m is rotated strongly. Since there is no need and a small generated torque is sufficient, a pattern with a low drive voltage is selected.

Conversely, when the difference signal is large, that is, when the difference between the target value and the actually measured value is large, the motor m must be rotated strongly, so that the generated torque is large, for example, a pattern signal such as 8-9. Is selected.

The correspondence between the difference signal and the drive signal (ie, pattern number) output according to the magnitude is predetermined.

As described above, the driving power corresponding to the magnitude of the difference signal is applied to the motor m. However, since the output shaft of the motor m is connected to the valve driving actuator, Even if the applied drive power is applied to the motor m, the degree of rotation of the motor m varies depending on the load applied to the valve. Therefore, the determination circuit also measures the degree of rotation of the motor m (that is, the amount of rotation per time, which determines whether the valve is moving).
When it is determined that the degree of rotation of the motor m is small, the determination circuit selects the next pattern number having a larger generated torque and outputs the driving voltage thereof. At this time, the operating angle signal of the motor m (that is, the opening signal of the valve) and the pattern number at which the valve started to move as a result of switching and increasing the drive voltage are stored in the nonvolatile memory. . The valve opening (that is, the actuator opening) and the value of the pattern number (drive parameter) at which the valve has started moving, which are stored in the nonvolatile memory, are output to an external communication device via a communication circuit and stored.

FIG. 2 shows the relationship between the actuator opening and the driving parameters output to the external communication device. As is clear from FIG. 2, the relationship between the actuator opening degree and the drive parameters is determined when the valve is installed for the first time (when the seat ring is new) and when the seat ring is deformed with time. Draw different curves. Therefore,
By recording the relationship between the actuator opening and the drive parameters, the degree of deformation of the seat ring can be known without dismantling the valve or actuator or dismantling the piping.

[0021]

The deformation of the seat ring over time can be checked by checking the change over time of the input value (drive voltage) to the motor with respect to the valve opening described above on the graph shown in FIG. The confirmation may be made by displaying data.

[0022]

As described above, the present invention relates to a valve seat deterioration detecting apparatus for detecting the deterioration of a valve seat of a valve driven by an electric actuator. A valve seat deterioration detecting device for a valve driven by an electric actuator, comprising a torque detecting device for detecting the change in the input value detected by the torque detecting device with time; ,
Alternatively, it is possible to know the degree of deterioration of the valve seat without having to disassemble the piping, and to obtain a highly reproducible detection result because a strain gauge or the like is not used. Also, at this time, when the change with time of the input value is displayed on a monitor, the change with time of the valve seat can be easily confirmed in real time. Furthermore, it is provided with a data table measured in advance regarding the change with time of the input value and the degree of deterioration of the valve seat, and when the change with time of the input value is detected, the deterioration degree of the valve seat is obtained from the data table, When this is displayed, the change with time of the valve seat can be confirmed in real time with a simple configuration without requiring a particularly complicated control device, which is convenient.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an information transmission path of a valve control circuit according to one embodiment of the present invention.

FIG. 2 is a graph showing a change over time in a relationship between a drive parameter and an opening degree of an actuator.

Claims (3)

[Claims] 1. A valve seat deterioration detecting device for detecting deterioration of a valve seat of a valve driven by an electric actuator, comprising: a torque detecting device for detecting an input value with respect to a valve opening of the electric actuator; An apparatus for detecting deterioration of a valve seat of a valve driven by an electric actuator, characterized by measuring a change with time of an input value detected by a torque detector. 2. The valve seat deterioration detecting device for a valve driven by an electric actuator according to claim 1, wherein a change over time of the input value is displayed on a monitor. 3. A data table which has been measured in advance with respect to a temporal change of an input value and a degree of deterioration of a valve seat, and
2. The valve seat deterioration detection of a valve driven by an electric actuator according to claim 1, wherein when a change with time of the input value is detected, a deterioration degree of the valve seat is obtained from the data table and displayed. apparatus.