JPH08121630A - Valve driving device - Google Patents

Abstract

PURPOSE: To easily and surely stop a valve element at the closing position. CONSTITUTION: A valve actuator opens/closes a valve arranged in the fluid transfer piping, and is provided with an electric motor M to drive the valve element of the valve, two limit switches LS1, LS2 to detect whether or not the valve opening is <=15%, and a torque switch CT2 which is turned off when the torque not less than the preset torque (for example, 50Nm) Is applied to the valve when the opening in the closing direction is <=15%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve drive device, and more particularly to a valve drive device for opening and closing a valve arranged in a fluid transfer pipe.

[0002]

2. Description of the Related Art In equipment such as oil refining plants and power plants, many valves are mounted on a fluid transfer pipe for transferring fluids such as oil, water and steam. The valve actuator that opens and closes this kind of valve includes a motor that drives the valve body, a limit switch that detects the fully closed position of the valve body, and the motor that stops when an abnormal load acts on the valve body. And a torque switch for controlling the operation. The torque switch is a switch that is turned off when a torque larger than a set value is applied, and one switch is provided in each of the opening direction and the closing direction. In this valve actuator, when a torque equal to or greater than the torque set value is applied to the valve element, the torque switch operates to stop the motor. Further, when the valve body reaches the fully closed position, the limit switch works to stop the motor.

[0003]

SUMMARY OF THE INVENTION In the above conventional configuration,
It is difficult to adjust the position of the limit switch in a valve such as a soft-seat butterfly valve that requires delicate adjustment at the fully closed position. For example, as shown in FIG. 5, opening 100% to opening 0% at point c
In the meantime, when the torque shown by the solid line acts on the valve body, and the opening at which the valve body contacts the soft seat is point a, the limit switch opens the valve at point b before the point a. When the body is detected, the valve body may not leak because the valve body is not in contact with the soft seat. On the contrary, when the limit switch detects the valve body at a point d of the opening farther back than the opening degree of 0% (point c), the valve body bites into the soft seat and damages the soft seat, etc. The problem of may occur. Therefore, it is necessary to adjust the limit switch to stop the valve body at the point c where the opening degree is 0%. These adjustments can be made only by delicate adjustments in which the position of the limit switch is set while watching the torque acting on the valve body. Moreover, if the number of valves is large, such adjustment must be performed for each valve, and the adjustment of the fully closed position of the valve body becomes complicated.

An object of the present invention is to enable the valve body to be easily stopped at the fully closed position.

[0005]

A valve drive device according to the present invention is a device for opening and closing a valve arranged in a fluid transfer pipe, the valve drive means for driving a valve body of the valve, and an opening degree. The detection means, the load detection means, the load setting means, and the stop means are provided. The opening detection means detects the opening of the valve. The load detecting means detects a load acting on the valve. The load setting means sets a load corresponding to the opening of the valve. The stop means stops the valve drive means when the load detection means detects a load equal to or higher than the load set by the load setting means.

[0006]

In the valve drive device according to the present invention, when the valve body of the valve is driven by the valve drive means, the opening degree thereof is detected by the opening degree detection means. Further, the load acting on the valve is detected by the load detecting means. Then, when the detected load exceeds the load set value corresponding to the opening degree of the valve which is predetermined by the load setting means, the stopping means stops the valve driving means. Here, since the load can be set according to the opening degree, for example, at an opening degree close to fully closed, the load is set when the valve body closes the flow path and hits the valve seat, and other loads are set. In terms of degrees, by setting the load to a value higher than the maximum load, the valve body can be stopped in the fully closed position easily and reliably.

[0007]

1 and 2, an automatic butterfly valve 1 according to an embodiment of the present invention comprises a valve body 2 and
It has a valve actuator 3. Valve body 2
Has a valve body 5, a soft seat 6 arranged in a ring shape along the inner circumference of the valve body 5, and a disc-shaped valve body 7 rotatable in the valve body 5 about a diameter axis. are doing. The rotary shaft 8 of the valve body 7 is arranged vertically in FIG.

The valve actuator 3 is arranged between the conversion mechanism 10 connected to the tip of the rotary shaft 8, the handle 11 connected to the conversion mechanism 10, the handle 11 and the conversion mechanism 10, and An electric motor M for rotating the rotary shaft, a switch mechanism section 12 for accommodating a limit switch for detecting the opening degree and three torque switches (both will be described later), and a control box 4 for controlling the valve actuator 3. Is equipped with.

The automatic butterfly valve 1 can be automatically opened / closed by the electric motor M, and can be manually opened / closed by the handle 11. An automatic manual switching lever 13 is provided below the valve actuator 3. The control box 4 is
Non-fuse breaker NFB connected to three-phase power supply 15
And a closing electromagnetic contactor CC and an opening electromagnetic contactor O arranged between the non-fuse breaker NFB and the electric motor M.
C. The opening electromagnetic contactor OC and the closing electromagnetic contactor CC are contactors for connecting two wires of the three-phase power source by interchanging them and rotating the electric motor M in the reverse direction. Further, one of the three-phase wires is connected to the operation switch COS. The other one is connected to the thermal relay THR.

The operation switch COS is a changeover switch having three terminals of an open side terminal CL, a closed side terminal OP and an OFF terminal OFF, and two limit switches LS1 and LS2 are connected in parallel to the open side terminal CL. ing. The limit switch LS1 is a switch that turns on at an opening of 15% or more. The limit switch LS2 is a switch that turns on when the opening is 15% or less. Limit switch LS1
And LS2 have torque switches CT1 and C, respectively.
T2 is connected. The torque switch CT1 is a switch that is turned off when the closing torque acting on the valve body 7 is 100 Nm or more. The torque switch CT2 is a switch that is turned off when the closing torque is 50 Nm or more. The torque switches CT1 and CT2 are collectively connected to the coil portion of the close side electromagnetic contactor CC. The open-side terminal OP of the operation switch COS is connected to the limit switch OLS that is turned off at the fully open position. Limit switch OLS is
It is connected to the torque switch OT1. The torque switch OT1 is a switch that is turned off when the open side torque is 100 Nm or more. Torque switch OT1 is open side electromagnetic contactor O
It is connected to the C coil section. Both coil parts are connected to the thermal relay THR.

Next, the operation of the above embodiment will be described. First, when opening the valve from the fully closed position (opening 0%) to the fully open position (opening 100%), the operation switch COS
To the open terminal OP side. At this time, since both the limit switch OLS and the torque switch CT1 are on, a current flows through the coil portion of the open side electromagnetic contactor OC, and the open side electromagnetic contactor OC is turned on. As a result, the motor M
Is reversed, the valve body 7 rotates in the opening direction, and the automatic butterfly valve 1 gradually opens. When the limit switch OLS is turned off, the electromagnetic contactor OC is opened, and the motor M is opened at the fully open position.
Stops.

On the contrary, when the automatic butterfly valve 1 is closed from the fully open position to the fully closed position, torque acts on the valve body 7 so that a peak appears in the middle as shown in FIG. 4, for example. In this case, set the operation switch COS to the close side terminal C
Switch to L side. Then, the opening is 100% to 1
The limit switch LS1 is closed up to 5%, and in the normal case where the torque does not exceed 100 Nm, the torque switch CT1 is also closed, so that a current flows through the coil portion of the close side electromagnetic contactor CC, and the close side electromagnetic contactor CC is closed. The contactor CC closes. As a result, the electric motor M rotates normally and the valve body 7 rotates in the closing direction. When the opening degree falls below 15%, the limit switch LS1 opens and the limit switch LS2 closes. When the valve body 7 contacts the soft seat 6 (point a in FIG. 4), the torque curve gradually rises. Torque is 50 Nm
When it exceeds, the torque switch CT2 is turned off and the closing side electromagnetic contactor CC is opened. As a result, the motor M stops. The torque at this time is set such that the valve body 7 is in proper contact with the soft seat 6, so that the valve body 7 reliably stops at the fully closed position.

Here, since the valve body 7 is stopped by the torque acting on the valve body 7, the valve body 7 can be stopped easily and reliably at the fully closed position. [Other Embodiments] (a) In the above embodiments, the three-phase motor was used as an electric motor, but in addition to the three-phase motor, a single-phase capacitor motor or a D
A C motor, an air motor, or a hydraulic motor may be used. (B) Two or more torque switches may be provided. Further, instead of the torque switch, a torque sensor and a microcomputer may be used to set an arbitrary torque at any arbitrary position from 0 to 100% of the opening. (C) Instead of the configuration in which the load is detected by the torque, the load may be detected by the current value to the motor or the pressure value to the hydraulic motor. In this case, the set current and the set pressure may be changed according to the opening.

[0014]

In the valve drive device according to the present invention, the load can be set in correspondence with the opening, so that, for example, when the opening is close to fully closed, the load acting when the valve body closes the flow path is reduced. The valve body can be easily and reliably stopped at the fully closed position by setting the load and setting the load to a value slightly higher than the maximum load at other opening degrees.

[Brief description of drawings]

FIG. 1 is a front view of an automatic butterfly valve that employs an embodiment of the present invention.

FIG. 2 is a side view of an automatic butterfly valve.

FIG. 3 is a sequence diagram of a control unit.

FIG. 4 is a graph showing the relationship between torque and opening.

FIG. 5 is a graph for explaining the conventional procedure for adjusting the detection position of the limit switch.

[Explanation of symbols]

 1 Automatic butterfly valve 2 Valve body 3 Valve actuator 7 Valve body M Electric motor LS2 Limit switch CT2 Torque switch

Claims (1)

[Claims] 1. A valve drive device for opening and closing a valve arranged in a fluid transfer pipe, the valve drive means for driving a valve body of the valve, and an opening degree detection means for detecting an opening degree of the valve. A load detecting means for detecting a load acting on the valve, a load setting means for setting a load corresponding to the opening of the valve, and a load equal to or more than the load set by the load setting means. A valve drive device comprising: stop means for stopping the valve drive means when detected by the detection means.