JPS647270B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an opening/closing control device for an electric valve, and particularly to an opening/closing control device for an electric valve having a structure suitable for making it possible to reliably display whether an electric globe valve is fully open or fully closed. It is related to.

Due to its structure and function, electric globe valves are
When fully closed, the valve seat and valve body must come into contact and sufficient surface pressure is generated before the valve can be fully closed.
Therefore, it is inappropriate to use a limit switch to detect the fully closed position and then stop the electric motor that is the driving source.It is therefore inappropriate to use a torque switch to detect that the required surface pressure has been obtained between the valve seat and the valve body. It must be detected and the motor must be stopped using that output. On the other hand, electric globe valves are often held at an intermediate opening position by remote control to perform throttling movements, so if the operator returns the remote control switch from the open (or closed) position to the neutral position, ,
It is necessary to stop the electric motor immediately and stop it at a predetermined opening degree.

FIG. 1 is a circuit diagram for controlling the opening/closing and displaying the opening/closing of a conventional electric globe valve. In Fig. 1, 1 is an electric motor, 2A ₁ and 2B ₁ are contactor contacts for rotating the electric motor 1 in forward and reverse directions, 3A,
3B is an operation switch, 2A and 2B are contactor relays, and 2A ₂ and 2B ₂ are relays 2A and 2B, respectively.
The auxiliary contacts 4A and 4B are torque switches that open when the drive torque of the electric motor 1 reaches a predetermined value, 5A ₁ , 5A ₂ , 5B ₁ and 5B ₂ are limit switches, and 6A and 6B are indicator lights.

Next, the operation will be explained using the closing operation as an example. When the operator turns on the operating switch 3B, the contactor relay 2B is energized and its auxiliary contact _2B2 is opened, preventing it from opening, and the contactor contact _2B1 is closed, causing the motor 1 to operate the electric globe valve ( (not shown) in the direction of the closing operation. When the electric motor starts, it generates an impact force, which may cause temporary overtorque and cause the torque switch 4B to open. However, since the limit switch _5B1 is connected in parallel with the torque switch 4B, the electric motor 1 never stops. When the electric globe valve starts its closing operation and the valve stem begins to move, the limit switch _5B1 opens, and thereafter the closing operation continues until the torque switch 4B opens due to overtorque. When the electric globe valve is fully closed, the valve stem stops moving, the rotational speed of the electric motor 1 suddenly decreases, and the torque increases. When the torque exceeds the set torque of the torque switch 4B, the torque switch 4B closes. Since the circuit is opened and the contactor relay 2B is no longer excited, the contactor contact _2B1 is opened and the motor 1 is stopped. At this time, the limit switch _5B2 is opened, the red indicator light 6B goes out, and only the green indicator light 6A lights up, indicating that the electric valve is fully closed. The operator releases the operating switch 3B when the red indicator light 6B goes out.

In the above case, in the electric globe valve, when adjusting the opening position of the limit switch _5B2 , the valve seat and the valve body are in contact, and it is possible to determine whether the surface pressure is sufficient or insufficient. This is extremely difficult as there is no difference in the strokes of the rods, resulting in insufficient adjustment. By the way, if there is a slight deviation in the position where limit switch _5B2 opens,
Even though the electric globe valve is normally fully closed, the indicator light 6B may not turn off, causing an inconvenience. Taking these points into consideration, there is a tendency to open the limit switch _5B2 a little before the position where the electric globe valve normally fully closes, but in this case, when the electric globe valve closes, the indicator light If the operator releases the operation switch 3B immediately after 6B goes out, the closing operation will stop just before the valve is fully closed, which will impair the basic function of the valve to completely close the fluid. Furthermore, if the valve is slightly opened and subjected to a high differential pressure, the sealing surfaces of the valve seat and valve body may suffer erosion damage.

SUMMARY OF THE INVENTION An object of the present invention is to provide an opening/closing control device for a motor-operated valve that can completely close the fluid and can reliably display that the motor-operated valve is fully closed or fully open.

The features of the present invention include: a closing control means connected between two wirings connected to a motor that drives an electric valve; an opening control means connected between the two wirings in parallel with the closing control means; The close control means includes a closed display means connected between two wires in parallel with the close control means, and an open display means connected between the two wires in parallel with the open control means, and the close control means A parallel circuit with a first limit switch that operates in the fully closed position and a first torque switch that operates when the motor torque reaches a predetermined value, a close operation switch, and a motor-operated valve that closes when the close operation switch is turned on. The opening control means is configured by connecting in series means for operating the opening/closing means so as to rotate the motor in the direction in which the electric valve is fully open, and the opening control means operates when the electric valve is in the fully open position and the motor torque reaches a predetermined value. When the second works
Parallel circuit with torque switch, open operation switch,
and a means for operating the opening/closing means so as to reverse the motor in the direction of opening the electric valve when the opening operation switch is turned on, and a means for operating the opening/closing means is connected in series. A parallel circuit of a third limit switch that operates, a third torque switch that operates when the torque of the motor reaches the set torque value of the first torque switch, and a first indicator light are connected in series, The disclosure display means is
A parallel circuit between the 4th limit switch that operates when the electric valve is fully open and the 4th torque switch that operates when the motor torque reaches the set torque value of the 2nd torque switch, and the 2nd indicator light are connected in series. The reason is that it is structured as follows.

The present invention will be explained in detail below using the embodiment shown in FIG.

FIG. 2 is a circuit diagram showing one embodiment of the device of the present invention, and the opening/closing control circuit for the electric globe valve has the same circuit configuration as that in FIG. 1, and its explanation will be omitted here. In Figure 2, 5A ₂ and 5B ₂ are limit switches that open when the valve stem of the electric globe valve stops moving, and 4A ₂ and 4B ₂ drive electric globe valves that are connected in parallel to the limit switches 5A ₂ and 5B ₂ , respectively. a torque switch that opens when the torque of the electric motor reaches a predetermined value;
6A and 6B are green and red indicator lights connected in parallel to the power supply, respectively, and the parallel circuit of the limit switch 5A ₂ and torque switch 4A ₂ described above, and the parallel circuit of the limit switch 5B ₂ and torque switch 4B ₂ are connected in series. It's connected.

Next, the operation will be described using as an example the closing operation of an electric globe valve (not shown). When the electric globe valve approaches full close and reaches the set position of the limit switch _5B2 , the limit switch _5B2 opens. However, the torque switch _4B2 remains closed until the driving torque of the electric motor 1 (see Fig. 1) reaches a state where the valve seat and the valve body are in contact and sufficient surface pressure is obtained. Indicator lights 6A and 6B are lit. From this state, the electric globe valve continues to close, the contact pressure of the sealing surface between the valve seat and the valve body increases, and when the driving torque of the electric motor 1 reaches a predetermined value, the torque switch 4B ₂ ( The setting value is the same as that of torque switch 4B in Fig. 1.)
is opened and the indicator light 6B goes out. Therefore,
This allows you to display that it is completely closed. In addition, in this case, even if only torque switch 4B ₂ is used,
Although they have the same effect, the limit switch _5B2 is connected in parallel so that when the electric globe valve becomes overtorque due to some abnormality at the intermediate opening and the torque switch _4B2 opens, the indicator light 6
This is to prevent the erroneous display of fully closed due to B being turned off.

Although the explanation is omitted here, the opening operation of the electric globe valve operates in almost the same way, and the indicator light 6
A can be turned off by opening the torque switch _4A2 when the electric globe valve is fully open.

According to this embodiment, the closing control means (auxiliary contact 2
A ₂ , contactor relay 2B, operation switch 3B,
Torque switch 4B and limit switch 5B ₁
) and a close indicating means (comprising a torque switch 4B ₂ , a limit switch 5B ₂ and an indicator light 6B) are connected in parallel to the wiring U and wiring W that supply current to the electric motor 1. Since the set torques of the switches 4B and _4B2 are the same value, the torque switch 4B of the close control means and the torque switch _4B2 of the close indication means are opened at the same time, the electric globe valve is fully closed, and the electric motor 1 is stopped. At the same time, the indicator light 6B goes out. Therefore, the indicator light 6B always indicates that the electric globe valve is fully closed when it is fully closed. In addition, the opening control means (auxiliary contact 2B ₂ ,
contactor relay 2A, operation switch 3A, torque switch 4A, and limit switch 5A ₁ ), open display means (torque switch 4
A ₂ , a limit switch 5A ₂ and a display 6A) are connected in parallel to the wiring U and the wiring W,
Moreover, since the set torque of torque switches 4A and 4A ₂ is the same value, the indicator light 6A of the open indicator means
Similarly, when the electric globe valve is fully opened and the electric motor 1 is stopped, the light is turned off. For this reason,
The indicator light 6A always indicates that the electric globe valve is fully open when it is fully open.

Since the closing control means includes the torque switch 4B and the limit switch _5B1 arranged in parallel, the electric globe valve can be reliably fully closed, and the fluid flowing inside the valve can be completely closed. For this reason, the valve seat of the electric globe valve,
It is possible to prevent the sealing surface of the valve body from being damaged by erosion.

As explained above, according to the present invention, when the electric globe valve is completely fully closed or fully open, it is possible to reliably display that the electric globe valve is fully closed or fully open, and to prevent fluid from flowing. It is now possible to completely close the valve, preventing erosion damage to the sealing surfaces of the valve seat and valve body, and also delaying the opening/closing operation of the electric globe valve for a while after the fully closed or fully open indication is displayed. This has the effect of making consideration unnecessary.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram for performing open/close control and open/close display of a conventional electric globe valve, and FIG. 2 is a circuit diagram showing an embodiment of the open/close display device of the present invention. 1...Electric motor, 2A, 2B...Contactor relay, 2A ₁ , 2B ₁ ...Contactor contact, 3A, 3
B...Open and close operation switch, 4A, 4 respectively
B, 4A ₂ , 4B ₂ ...torque switch, 5A ₁ , 5
B ₁ , 5A ₂ , 5B ₂ ... Limit switch, 6A,
6B... Indicator light.

Claims (1)

[Claims] 1. A motor that drives an electric valve, an opening/closing means for controlling forward and reverse rotation of the motor by switching the connection state of wiring connected to the motor, a closing control means connected between two of the wirings, and a closing control means connected between the two wirings; an open control means connected between the two wires in parallel with the close control means;
a closed display means connected between the two wires in parallel with the close control means; and an open display means connected between the two wires in parallel with the open control means, the close control means However, a parallel circuit of a first limit switch that operates when the electric valve is in the fully closed position and a first torque switch that operates when the torque of the motor reaches a predetermined value, a closing operation switch, and the closing operation switch being turned on. means for operating the opening/closing means are connected in series so as to rotate the motor in a direction to close the electric valve when the electric valve is opened, and the opening control means operates at a fully open position of the electric valve. A parallel circuit of a second limit switch and a second torque switch that operates when the torque of the motor reaches a predetermined value, an opening operation switch, and a direction that opens the electric valve when the opening operation switch is turned on. Means for operating the opening/closing means so as to reverse the motor is connected in series, and the close indicating means is configured such that the third limit switch operates at the fully closed position of the electric valve and the third limit switch operates when the torque of the motor is at the third limit switch. It is configured by connecting in series a parallel circuit with a third torque switch that operates when the set torque value of the first torque switch is reached, and a first indicator light, and the open indicating means indicates when the electric valve is in the fully open position. A parallel circuit of a fourth limit switch that operates when the torque of the motor reaches a set torque value of the second torque switch, and a second indicator light are connected in series. An electric valve opening/closing control device characterized by: