JP2015222229A - Load measurement apparatus of valve stem and load measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a load measurement apparatus of a valve stem allowing a valve stem load sensor measuring a load applied to the valve stem to be mounted to the valve stem at all times in a detachable state, and further to provide a load measurement method thereof.SOLUTION: A valve stem load sensor 10 comprises: a semi-circular arc-shaped main body portion 26; and a recess portion 27 formed at an outer surface side of a central portion of the main body portion 26. Further, a strain gauge 7 is provided in an area having a plate thickness reduced by the recess portion 27. A pair of gripping rods 28a and 28b are provided so as to extend from both end edges of the main body portion 26. Gripping members 29 gripping a valve stem 2 are provided at end portions of the pair of gripping rods 28a and 28b. The valve stem load sensor 10 can be fixed to the valve stem 2 or to guides 6 by an electromagnet 8 provided in an area facing the recess portion 27.

Description

  Embodiments described herein relate generally to a valve rod load measuring device and a load measuring method for measuring a load acting on a valve rod that operates a valve body of the valve device.

  2. Description of the Related Art Conventionally, in various plants such as a power plant, a state monitoring technique for measuring a load acting on a valve stem has been applied as a preventive maintenance measure for a valve device. The valve stem connects the drive unit and the valve body, and plays a role of transmitting driving force from the drive unit to the valve body. Therefore, by measuring the load acting on the valve stem, it is possible to monitor the state of the drive unit and the valve unit for abnormalities.

  For example, there is a measurement technique described in Patent Documents 1 and 2 for performing state monitoring for abnormalities of the drive unit and the valve unit. In this measurement technique, a valve rod load sensor equipped with a strain gauge is attached to a part of the valve rod, and the load acting on the valve rod can be measured by the valve rod load sensor.

Japanese Patent No. 2716809 Japanese Patent No. 4540978

  Even if it is going to apply the prior arts described in Patent Documents 1 and 2, there are many valve devices in which the space for attaching the valve rod load sensor to the valve rod is narrow due to structural problems of the valve device. . Therefore, if the valve stem is moved to the full stroke position with the valve stem load sensor attached to the valve stem, a situation occurs in which the valve stem load sensor contacts the yoke during the stroke.

  When the valve stem load sensor contacts the yoke, the load acting on the valve stem cannot be measured. Therefore, there is a problem that there is a region where the load on the valve stem cannot be measured within the entire stroke range up to the full stroke position.

  In addition, the valve rod load sensor cannot be attached to the valve rod in a permanent manner, and the load acting on the valve rod cannot be always measured. Therefore, every time the load acting on the valve stem is measured and data is obtained, the valve stem load sensor is attached to the valve stem, adjusted, and the measurement work is performed. The work which removes a sensor from a valve stem is needed. As a result, there is a problem that the amount of work required for data measurement becomes large and the work time becomes long.

  The present invention provides a valve stem load measuring device and a load measuring method thereof, in which a valve stem load sensor for measuring a load acting on the valve stem can be always attached in a detachable state to the valve stem. With the goal.

  In order to solve the above problems, a valve stem load measuring device according to an embodiment of the present invention includes a valve body housed in a valve box, a valve rod for operating the valve body, and a drive for driving the valve stem. A load measuring device for a valve stem that measures a load acting on the valve stem in a valve device comprising: a strain gauge and an electromagnet; and mounting to the valve stem by electromagnetic force of the electromagnet; And a valve stem load sensor configured to be able to be released from the mounted state.

  The load measuring method for a valve stem according to an embodiment of the present invention includes a valve body housed in a valve box, a valve rod for operating the valve body, and a drive unit for driving the valve rod. A load measuring method for measuring a load acting on the valve stem in a valve device, wherein a valve rod load sensor equipped with a strain gauge and an electromagnet is attached to the valve stem by electromagnetic force of the electromagnet, and the valve The mounting state with the rod is released and the valve device is fixed to the yoke side, and the strain amount of the valve rod is measured during the operation of the valve device by the strain gauge, and the measured strain A load acting on the valve stem is calculated based on the amount.

  According to the embodiment of the present invention, the valve rod load sensor for measuring the load acting on the valve rod can be always mounted in a state where it can be attached to and detached from the valve rod.

It is a schematic sectional drawing of a motor operated valve. It is the enlarged view (a) of the part enclosed with the dotted line circle of FIG. 1, and BB sectional drawing (b) of FIG. 2 (a). It is a block diagram which shows the structure of a load measuring device. It is a flowchart which shows the process of a load measuring method. It is an example of a waveform which shows the time-axis change of the load which acts on a valve stem.

  Hereinafter, embodiments of a load measuring device and a load measuring method for a valve stem according to the present invention will be described with reference to the drawings.

(Valve stem load measuring device)
FIG. 1 shows a schematic cross-sectional view of a motor-operated valve as one type of valve device 25 as an example of a valve device to be monitored, and FIG. 2 (a) is a portion surrounded by a dotted circle in FIG. The figure which expanded is shown. Moreover, FIG.2 (b) has shown the load measuring apparatus 20 using the BB sectional drawing in Fig.2 (a). In FIG. 3, the block which shows the structure of the load measuring apparatus 20 which measures the load of the valve stem 2 is shown. FIG. 4 is a flowchart showing the steps of the load measuring method performed using the load measuring device 20. FIG. 5 shows an example of a time-axis waveform of the load acting on the valve stem 2 measured by the load measuring device 20.

  The configuration of the valve stem load measuring device will be described with reference to FIGS. The valve body 1 is accommodated in a valve box 3 constituting the valve device 25, one end of the valve stem 2 is connected to the valve body 1, and the end on the other end side is led out to the outside of the valve box 3. It is connected to the electric drive unit 4.

  The upper opening of the valve box 3 is sealed by a lid 3b, and the valve stem 2 protrudes to the outside from a hole formed in the lid 3b while being sealed in a liquid-tight state. When the valve stem 2 moves in the vertical direction, the fluid flowing in the valve box 3 is configured not to leak to the outside by a seal member (not shown) provided between the valve stem 2 and the lid 3b.

  As indicated by the arrows, the valve box 3 is provided in the middle of the flow path for flowing the fluid flowing in from the left side of FIG. 1 to the right side, and by seating the valve body 1 on the valve seat 3a, the left side of the fluid The flow to the right side can be cut off. And the flow volume of the fluid which flows from the left side to the right side can be controlled by adjusting the space | interval of the valve body 1 and the valve seat 3a.

  The configuration of the valve box 3 has been described using an example in which the fluid flows from the left side to the right side. However, even when the fluid flows from the right side to the left side, the distance between the valve body 1 and the valve seat 3a is adjusted. By doing so, the flow rate of the fluid flowing through the valve box 3 can be controlled.

  In order to control the flow rate of the fluid flowing in the valve box 3, the distance between the valve body 1 and the valve seat 3a is controlled by the amount of movement when the valve rod 2 that moves the valve body 1 up and down is moved in the vertical direction. Can do. The vertical movement of the valve stem 2 can be performed by the electric drive unit 4.

  That is, by transmitting the operating force generated by the electric drive unit 4 to the valve rod 2, the valve body 1 is moved in the vertical direction, and the amount of clearance between the valve body 1 and the valve seat 3a is adjusted. The flow of the fluid in the valve box 3 can be cut off and the flow rate can be adjusted.

  The operating force required to move the valve body 1 in the vertical direction includes frictional force generated between the valve body 1 and the valve seat 3a and when the valve rod 2 slides in the hole formed in the lid 3b. The pressure contact state is released from the state in which the valve body 1 is pressed against the valve seat 3a by the resistance force, the resistance force generated between the fluid in the valve box 3 and the valve body 1 and the valve stem 2, and the inertia of the electric drive unit 4. It is set in consideration of these necessary forces such as the necessary force.

  When the operating force is transmitted to the valve stem 2 and the valve stem 2 and the valve body 1 are driven, a load is applied to the valve stem 2. Since the valve stem 2 is configured to connect the electric drive unit 4 that receives the operation force and the valve body 1 that applies the operation force, the load acting on the valve rod 2 is the electric drive unit 4 and the valve body. It functions as a highly sensitive parameter for abnormalities related to 1.

  When an abnormality occurs in the electric drive unit 4 or the valve body 1, the load acting on the valve stem 2 changes from the normal state. For this reason, abnormalities related to the electric drive unit 4 and the valve body 1 can be detected by periodically measuring the load acting on the valve stem 2 and monitoring the change tendency of the load.

  In the present embodiment, as shown in FIG. 1, a guide 6 is provided inside the yoke 5 of the valve device 25, and the valve is driven by the electromagnetic force of the electromagnet 8 mounted inside the valve rod load sensor 10. The rod load sensor 10 is configured to be detachable from the valve stem 2.

  That is, as shown in FIG. 2 (b), the valve stem load sensor 10 has a shape including a semicircular arc-shaped main body portion 26 and a concave portion 27 formed in the central portion on the outer surface side of the main body portion 26. It is configured. A pair of gripping rods 28 a and a pair of gripping rods 28 b extending from the both end edges of the main body 26 to the inner and outer diameter sides of a semicircular arc are provided. A gripping member 29 that grips the valve stem 2 is provided at the end of each gripping rod 28a.

  Electromagnets 8 are mounted on the opposing portions of the recess 27, respectively. By supplying a power supply voltage to the pair of electromagnets 8 to generate an electromagnetic force, the pair of electromagnets 8 can generate a repulsive force to reduce the diameter of the semicircular main body 26 inward. When the diameter of the main body portion 26 is reduced inward, the gripping members 29 provided at the end portions of the pair of gripping rods 28a move in directions close to each other and come into contact with the valve stem 2 to grip the valve stem 2. Can do. Thereby, the valve stem load sensor 10 can be fixed to the valve stem 2.

  On the other hand, when the power supply voltage supplied to the pair of electromagnets 8 is cut off, the repulsive force generated between the pair of electromagnets 8 disappears, and the main body portion 26 that has been reduced in diameter returns elastically. When the main body portion 26 is elastically restored, the pair of gripping members 29 that have gripped the valve stem 2 are separated from the valve stem 2, and conversely, the pair of gripping rods 28b extending from the main body portion 26 to the outer diameter side are The end of each grip rod 28b can be brought into pressure contact with the inner surface of the guide 6 by moving in the direction of expanding the diameter.

  Thereby, the valve stem load sensor 10 separated from the valve stem 2 can be fixed to the guide 6 without dropping downward. A gripping member similar to that provided at the ends of the pair of grip rods 28a may be provided at the ends of the pair of grip rods 28b.

  The repulsive force between the pair of electromagnets 8 releases the valve stem load sensor 10 from the gripped state of the valve stem 2, fixes the valve stem load sensor 10 to the guide 6, and the repulsion between the pair of electromagnets 8. By releasing the force, the valve rod load sensor 10 can be changed from being fixed by the guide 6 to being gripped by the valve rod 2. And by attracting | sucking in the direction which attracts | sucks the attraction | suction force between a pair of electromagnets 8 and mutual, it can hold | grip to the valve stem 2 and can fix to the guide 6. FIG.

  The power supply voltage supplied to the electromagnet 8 can be feedback-controlled by the power supply voltage control unit 15 shown in FIG. Then, by controlling the electromagnetic force generated by each electromagnet 8, the gripping force for gripping the valve stem 2 by the gripping member 29 can be adjusted so as to be within an appropriate range.

  After adjusting the gripping force on the valve stem 2 by the gripping member 29, a strain gauge 7 is provided in a portion where the plate thickness in the vertical direction is reduced by the concave portion 27 in the valve stem load sensor 10, and the strain acting on the valve stem 2. Measure the amount. When the supply of the power supply voltage to each electromagnet 8 is interrupted, the repulsive force between the pair of electromagnets 8 disappears, and the valve stem load sensor 10 is detached from the valve stem 2 and fixed to the guide 6.

  Normally, the power supply voltage is not supplied to the valve stem load sensor 10, and the valve stem load sensor 10 is detached from the valve stem 2 and is fixed to the guide 6. Therefore, the valve stem load sensor 10 does not affect the operation of the valve device 25 with respect to the movement of the valve stem 2. On the other hand, when performing data measurement, a power supply voltage is supplied to the pair of electromagnets 8, and the valve stem load sensor 10 is fixed to the valve stem 2.

As shown in FIGS. 2B and 3, a displacement sensor 9 is mounted on the valve rod load sensor 10, and the distance between the valve rod load sensor 10 and the yoke 5 can be measured.
In FIG. 2B, the displacement sensor 9 is arranged on the upper surface of the main body portion 26 at the left side of the valve stem 2, but on the lower surface of the main body portion 26 at the right side of the valve stem 2. Alternatively, a displacement sensor 9 can be provided. Thus, by arranging the displacement sensors 9 on both sides of the main body 26, the horizontal balance of the main body 26 can be maintained. The distance between the left side portion of the main body 26 and the yoke 5 in FIG. 2B can be measured by the displacement sensor 9 disposed on the upper surface of the main body 26, and the displacement sensor disposed on the lower surface of the main body 26. 9, the distance between the right side portion of the main body 26 and the lower portion of the yoke 5 can be measured.

  The value measured by the displacement sensor 9 is input to the power supply voltage control unit 15 of the electromagnet 8. In order to prevent the valve stem load sensor 10 from contacting the yoke 5 and the guide 6 provided inside the yoke 5, the power supply voltage control unit 15 uses the detection signal from the displacement sensor 9 to detect the difference between the valve stem load sensor 10 and the yoke 5. When the interval becomes a predetermined interval, the power supply voltage supplied to each electromagnet 8 can be controlled.

  When the power supply voltage supplied to each electromagnet 8 is cut off, the valve stem load sensor 10 is detached from the gripping state of the valve stem 2 and is fixed to the guide 6. The strain amount measured by the strain gauge 7 of the valve stem load sensor 10 is A / D converted by the signal processing unit 11 to become a digital value. The strain amount data obtained in this way can be transmitted via a network to a remote location, for example, the analysis unit 12 in the central control room of the plant.

  In the analysis unit 12, the load acting on the valve stem 2 based on the shape and material coefficient of the valve stem 2 based on the time axis waveform obtained with respect to the strain amount of the valve stem 2 during the valve operation measured by the strain gauge 7. Convert to time axis waveform. The time axis waveform of the load acting on the valve stem 2 is displayed on the display unit 13 and stored in the database unit 14 for history management.

(Valve stem load measurement method)
A valve stem load measuring method using the present valve stem load measuring apparatus will be described with reference to FIGS. Before measuring the strain data of the valve stem 2, the power supply voltage is supplied to the electromagnet 8 mounted on the valve stem load sensor 10 while the valve device 25 is stopped, and the valve stem load sensor 10 is connected to the valve stem. (Step 101).

  At this time, the power supply voltage control unit 15 can adjust the electromagnetic force generated by the pair of electromagnets 8 by feedback control of the power supply voltage supplied by each electromagnet 8, and the gripping provided on the gripping rod 28 a. Adjustment is made so that the gripping force of the member 29 against the valve stem 2 falls within an appropriate range (step 102).

After adjusting the gripping force by the pair of gripping members 29, the valve device 25 is operated (step 103).
During the operation of the valve device 25, the time axis waveform relating to the strain amount of the valve stem 2 is measured by the valve stem load sensor 10 (step 104).

  If the distance between the valve stem load sensor 10 and the yoke 5 reaches a predetermined interval during the operation of the valve device 25, the power supply voltage controller 15 cuts off the power supply voltage supplied to the electromagnet 8 and the valve stem. The load sensor 10 is detached from the valve stem 2 and fixed to the guide 6 (step 105).

A time axis waveform of the strain amount of the valve stem 2 measured by the strain gauge 7 is A / D converted in the signal processing unit 11. The digitally converted time axis waveform is converted into a time axis waveform of the load acting on the valve stem 2 based on the shape of the valve stem 2 and the material coefficient in the analysis unit 12. The time axis waveform of the load is as shown in FIG. 5 and is displayed on the display unit (step 106).
Based on the time-axis waveform of the displayed load, the load for each operation event of the valve device 25 is stored in the database unit 14 (step 107).

  For example, as shown in FIG. 5, the operation event of the valve device 25 can be regarded as each stage of (1) to (13). In the valve device 25 in the fully closed state, the stage shown by (1) is that when the opening operation is performed by the valve body 1, the motor that moves the valve rod 2 up and down in the electric drive unit 4 is activated. This is a stage at the time of “motor start” when the gear connected to the motor starts to rotate.

The stage indicated by (2) is a stage at the time of “hammer blow” in which the rotation of the motor is transmitted by the gear within the electric drive unit 4 and the gear connected to the valve stem 2 starts to rotate.
The stage indicated by (3) is a stage at the time of “no valve stem no load” in which the connection state between the gear and the valve stem 2 is momentarily loosened immediately after hammer blow.

The stage indicated by (4) is a stage at the time of “valve stem opening operation start” in which only the valve stem 2 starts to open the valve body 1.
The stage indicated by (5) is a stage at the time of “valve element opening operation start” in which the valve rod 2 starts the opening operation in the valve device 25 together with the valve element 1.

  The stage indicated by (6) is a stage at the time of “motor stop” when the open limit switch arranged in the electric drive unit 4 is in an open state and the motor stops. In this state, the valve body 1 is separated from the valve seat 3a, and the valve device 25 is fully opened.

  Next, when closing the valve device 25 in the fully open state, the stage shown in (7) is the time when the motor is started in the electric drive unit 4 and the gear connected to the motor starts rotating. It is a stage.

The stage indicated by (8) is a stage at the time of “hammer blow” in which the rotation of the motor is transmitted by the gear in the electric drive unit 4 and the gear connected to the valve stem 2 starts to rotate.
The stage indicated by (9) is a stage at the time of “no valve stem no load” in which the connection state between the gear and the valve stem 2 is momentarily loosened immediately after hammer blow.

The stage indicated by (10) is a stage at the time of “valve element closing operation start” in which the valve rod 2 starts the closing operation in the valve device 25 together with the valve element 1.
The stage indicated by (11) is a stage at the time of “valve seat” in which the valve body 1 comes into contact with the valve seat 3a.

The stage shown in (12) is a stage at the time of “motor stop” in which the closed torque switch is opened in the electric drive unit 4 and the motor is stopped.
The stage indicated by (13) is a stage at the time of “valve element operation stop” in which the operation of the valve element 1 is stopped by stopping the motor.
Each of these stages is listed as an operation event.

  The display unit 13 confirms the change between the time axis waveform of the load acting on the valve stem 2 measured this time, the load measured for each operation event of the valve device 25, and the load obtained from the past measurement result. Trend graph and past evaluation results are displayed (step 108).

Based on the display result, the evaluation result for the current measurement result is stored in the database unit 14 (step 109).
By performing Step 101 to Step 109, the load acting on the valve stem 2 can be measured.

  In addition to the valve stem load sensor 10, for example, if the valve device 25 is an electric valve, the valve device 25 is permanently installed together with sensors for measuring the motor current and voltage, the limit switch, and the torque switch ON / OFF time. Can be made. By comprising in this way, several data can be measured simultaneously and the comprehensive state monitoring with respect to the valve apparatus 25 can be performed.

  In the prior art, as described in the section of the problem to be solved by the invention, the valve stem cannot be operated to the full stroke position with the valve stem load sensor attached in many cases. Therefore, it has been difficult to measure the load acting on the valve stem with the valve rod load sensor permanently installed. For this reason, it is necessary to go to the site every time data measurement is performed, attach the valve rod load sensor to the valve rod, perform adjustment, perform measurement, and then remove the valve rod load sensor from the valve rod. Therefore, the data measurement requires a large amount of work and a long work time.

  As described above, according to the present embodiment, the above-described operation that was necessary in the prior art for each data measurement is not required, and the amount of work required for data measurement and the operation time can be reduced.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, combinations, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1 ... Valve body, 2 ... Valve rod, 3 ... Valve box, 4 ... Electric drive part, 5 ... Yoke, 6 ... Guide, 7 ... Strain gauge, 8 ... Electromagnet, 9 ... Displacement sensor, 10 ... Valve rod load sensor, DESCRIPTION OF SYMBOLS 11 ... Signal processing part, 12 ... Analysis part, 13 ... Display part, 14 ... Database part, 15 ... Power supply voltage control part, 20 ... Load measuring device, 25 ... Valve apparatus, 26 ... Main-body part, 27 ... Recessed part, 28a, 28b: gripping rod.

Claims (8)

A valve rod load for measuring a load acting on the valve rod in a valve device having a valve body housed in a valve box, a valve rod for operating the valve body, and a drive unit for driving the valve rod. A measuring device,
A valve rod load sensor that is equipped with a strain gauge and an electromagnet, and is configured to be able to be mounted on the valve rod and released from the mounted state by the electromagnetic force of the electromagnet;
A load measuring device for a valve stem, comprising: The valve stem load sensor includes a semicircular arc main body, and a recess formed on the outer surface side in the center of the main body,
The strain gauge is provided in the central portion;
A pair of gripping rods extending from the both end edges of the main body to the inner diameter side and the outer diameter side are formed, respectively.
The valve rod load measuring device according to claim 1, wherein a pair of electromagnets are provided at portions of the concave portion facing each other.   The power supply voltage control part which adjusts the electromagnetic force of the said electromagnet in an appropriate range by feedback-controlling the power supply voltage supplied to the said electromagnet is provided. Valve stem load measuring device. A displacement sensor for measuring the distance between the valve stem load sensor and the yoke of the valve device is mounted on the valve stem load sensor,
The power supply voltage control unit shuts off the power supply voltage to the electromagnet when the interval becomes a predetermined interval according to a detection signal from the displacement sensor, and the valve stem load sensor is attached to the valve stem. The valve rod load measuring device according to claim 1, wherein the valve rod load measuring device is fixed to the yoke side. A signal processing unit for A / D converting the time-axis waveform of the strain amount detected by the valve stem load sensor;
An analysis unit that converts a time-axis waveform of a strain amount converted into a digital value by the signal processing unit into a time-axis waveform of a load acting on the valve stem based on the shape and material coefficient of the valve stem. When,
A display unit for displaying a time-axis waveform of the load;
A database unit for storing the load data and performing history management;
5. The valve stem load measuring device according to claim 1, comprising: A load measuring method for measuring a load acting on the valve stem in a valve device having a valve body housed in a valve box, a valve stem for operating the valve body, and a drive unit for driving the valve stem. There,
A valve rod load sensor equipped with a strain gauge and an electromagnet is attached to the valve stem by electromagnetic force of the electromagnet, and fixed to the yoke side of the valve device by releasing the attachment state of the valve stem, Switching to
The strain gauge measures the amount of strain of the valve stem during operation of the valve device, and calculates a load acting on the valve stem based on the measured strain amount. Load measurement method.   7. The valve stem load measuring method according to claim 6, wherein a power supply voltage supplied to the electromagnetic force is feedback-controlled so that the electromagnetic force of the electromagnet falls within an appropriate range. Measuring the distance between the valve stem load sensor and the yoke of the valve device with a displacement sensor mounted on the valve stem load sensor;
When the interval is narrowed to a predetermined interval by a detection signal from the displacement sensor so that the valve stem load sensor does not contact the yoke, the power supply voltage for controlling the electromagnetic force is cut off, and the valve stem load is 8. The valve stem load measuring method according to claim 6 or 7, wherein the sensor is released from the mounting state with the valve stem and fixed to the yoke side.

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