JP2003156168A - Motor-driven opening-closing method and device of valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving method and a device which fully closes a valve element by automatically exhibiting large driving force when an electric driving device is incapable of fully closing the valve element by ordinary force when using a valve. SOLUTION: A speed reducer including a worm mechanism and a capacitor induction electric motor are used. In the capacitor induction electric motor, a second capacitor is connected in parallel to a first capacitor in a circuit including the normally installed first capacitor. The worm mechanism measures force required for a worm to rotate a worm wheel. In the beginning, the valve element is opened and closed without operating the second capacitor. When the force for the worm to rotate the worm wheel exceeds a preset value, the valve element is opened and closed by operating the second capacitor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric valve opening / closing method and an apparatus thereof.

[0002]

2. Description of the Related Art In general, a valve has a valve body movably fixed in a valve body. Explaining the butterfly valve as an example, the valve body has a cylindrical portion that allows fluid to pass through, while the valve body consists of a disk that is just large enough to close the cylinder. A valve shaft extending parallel to the disc surface is provided at the position. A butterfly valve has a valve body housed in a cylindrical portion of such a valve body, and has a valve shaft rotatably fixed to a wall of the cylindrical portion so that the valve body opens and closes the cylindrical portion.

In the butterfly valve, a seat ring is often attached to the inner surface of the cylindrical portion of the valve body in order to bring the outer periphery of the valve element into close contact with the inner surface of the cylindrical portion of the valve body when the valve body is fully closed. The seat ring is made of synthetic rubber or synthetic resin, and is made of a softer material than the valve body. For this reason, the surface of the seat ring is apt to be roughened by the contact with the fluid, and is easily rubbed by the valve body to be worn. Therefore, while the valve is in use, the outer circumference of the valve body gradually becomes difficult to come into close contact with the inner surface of the seat ring.

Generally, a large force is required when trying to fully close the valve. This is because, in order to bring the outer circumference of the valve body into close contact with the seat ring, in addition to the force to rotate the valve body, the valve body further overcomes the frictional force with the inner surface of the seat ring to bring the valve body into close contact with the seat ring. Because it must be. When trying to rotate the valve body by the drive device, taking this into consideration,
A powerful drive with sufficient reserve is attached to the valve.

In an electric drive device, a capacitor induction motor is used as a prime mover. This electric motor is suitable for turning the valve body because the rotation direction can be reversed by changing the flowing direction of electricity. Therefore, the capacitor induction motor is widely used for opening and closing the valve.

When rotating the valve body electrically, a reduction gear is attached to the output shaft of the electric motor to reduce the rotational speed of the electric motor. Generally, gear meshing is used to reduce the rotation speed. Among the meshing of gears, the meshing of spur gears has an advantage that it does not require a large space, but has a drawback that it cannot significantly reduce the speed. On the other hand, the meshing of the worm and the worm wheel has advantages and disadvantages exactly opposite to those of the spur gear. Therefore, both of the above are used together for deceleration. Therefore, the decelerator always uses the mesh of the worm and the worm wheel.

As mentioned above, it is generally more and more difficult for the valve to fully close the valve body during continuous use. Therefore, a gradually increasing force is required to bring the valve into the fully closed state. Therefore, even a drive device having a sufficient reserve capacity at the beginning gradually loses the reserve capacity, and finally the valve cannot be fully closed even if the maximum drive force is exerted. If this happens, the drive must be replaced. The replacement of the drive device has hitherto been carried out by replacing the electric motor to increase the capacity of the electric motor or replacing the reduction gear to increase the reduction ratio.

However, for a valve that has been used for a while, it is not a good idea to replace the electric motor or speed reducer attached to the valve, which involves great expense. Instead,
It is more wasteful to use a motor with a larger capacity or a reducer with a larger reduction ratio from the beginning. Therefore, it was necessary to improve this point.

[0009]

The present invention has been made in response to the above-mentioned needs. That is, according to the present invention, as the valve is used, even when the electric drive device exerts the maximum driving force, when the valve body cannot be fully closed, a large drive is automatically performed. It is an object of the present invention to provide a drive device that can exert force, and in particular, exerts only a small drive force until such a state occurs. The present invention also seeks to provide the driving method as described above.

[0010]

The present application has focused on the fact that a capacitor induction motor is used as a prime mover in a valve body drive device. As shown in FIG. 1, a capacitor induction motor has a starting capacitor connected to a circuit including a main winding and an operating capacitor in parallel with the operating capacitor together with a centrifugal force switch in order to connect the main winding and the starting winding. It has a circuit that is connected in series. It has been found that, in such a circuit, if a second capacitor is additionally provided in parallel with the operating capacitor, the driving force of the electric motor can be further increased. Therefore, the second capacitor as described above is attached.

However, if the second capacitor is attached and is always operated from the beginning, a large amount of electric power is consumed as in the case of attaching a large capacity electric motor, which is uneconomical. Therefore, a switch is attached to the second capacitor so that the switch works only when the electric motor has insufficient power so that the second capacitor operates.

In this case, the problem is how to detect that the electric motor has insufficient power. The present application has attempted to detect a situation where the power of the electric motor is insufficient by the operating state of the speed reducer. In other words, paying attention to the fact that the speed reducer normally uses a speed reduction mechanism that meshes a worm and a worm wheel, and measures the component force in the worm axis direction of the rotational force that the worm receives from the worm wheel. It was decided to measure the magnitude of the rotational force and detect the insufficient force of the electric motor when the rotational force exceeded a certain set value. Then, when the rotational force exceeds the set value, the switch operates so that the second capacitor operates.
The present invention has been completed based on such an idea.

According to the present invention, in a method of decelerating a rotational force of a capacitor induction motor by a worm mechanism and then transmitting the same to a valve shaft of a valve to open and close the valve, a circuit including a first capacitor usually attached to a capacitor induction motor. Then, a second capacitor is connected in parallel with the first capacitor together with a switch, and at first, the electric motor is operated to open and close the valve without operating the second capacitor. Measure the amount of force required to rotate,
A method for electrically opening and closing a valve is characterized in that when the magnitude of the force exceeds a set value, the switch automatically operates to operate the second capacitor.

The present invention also provides an electric valve opening / closing device. The device comprises a capacitor induction motor, a speed reducer including a worm mechanism, and connecting means for relating the movement of the worm mechanism to the movement of the capacitor induction motor, and the capacitor induction motor is usually equipped with a first condenser. A second capacitor is connected in parallel with the first capacitor to a circuit including the switch, and the worm mechanism is configured such that the worm can move on the worm shaft against the spring. It is characterized in that when the movement distance of the worm on the shaft exceeds a certain set value, the switch operates to actuate the second capacitor.

[0015]

DETAILED DESCRIPTION OF THE INVENTION The invention of the above method is believed to be readily understood by understanding the invention of the above apparatus, so the apparatus will first be described. In that case, FIG. 2 is a circuit diagram of the capacitor induction motor used in the present invention. Figure 3
FIG. 3 is an explanatory view showing a worm mechanism of the speed reducer used in the present invention.

An electric valve opening / closing device according to the present invention comprises:
A capacitor induction motor having a circuit arrangement as shown in FIG. 2, a speed reducer including a worm mechanism as shown in FIG. 3, and a connecting means for relating the movement of the worm mechanism to the movement of the capacitor induction motor. It consists of and.

As is apparent from comparison with FIG. 1, the motor shown in FIG. 2 includes a first capacitor in a circuit including an operating capacitor (that is, a first capacitor) which is generally included in a general capacitor induction motor. And a circuit in which a second capacitor is connected in parallel with the switch. When the switch is turned on, the second capacitor is activated and the motor increases its output. However, when the switch is turned off, the second capacitor does not operate, so that the output is equivalent to that of the conventional electric motor.

In the worm mechanism shown in FIG. 3, the rotation of the electric motor (not shown) is reduced by the engagement of spur gears (not shown) and then transmitted to the worm shaft of FIG. Both ends of the worm shaft are rotatably supported by ball bearings, and the worm mounted thereon is rotated. The worm meshes with the worm wheel. As a result, when the worm shaft is rotated, the worm wheel is rotated.
In this respect, the worm mechanism of FIG. 3 is no different from the conventional one.

The worm mechanism shown in FIG. 3 is different from the conventional one in that the worm is axially movable on the worm shaft. However, the worm is restrained from moving in the axial direction by a spring inserted between the worm and the ball bearing. That is, although the worm is movable in the axial direction, the movement of the worm is always urged toward the other ball bearing by the spring, so that the worm cannot move unless it is rotated.

In the worm mechanism of FIG. 3, when the worm shaft is rotated, the worm meshes with the worm wheel, so that the worm receives a reaction force of rotation from the worm wheel and moves in the Y direction against the spring. To do. The moving distance is proportional to the force that the worm receives from the worm wheel, that is, the magnitude of the rotating force of the worm. Therefore, the magnitude of the force required for the worm to rotate the worm wheel can be known from the above moving distance.

Thus, by connecting the valve shaft to the worm wheel shaft as the output shaft and measuring the moving distance of the worm, it is possible to know the magnitude of the force required for the electric motor to fully close the valve body. it can. Therefore, the situation in which the magnitude of this force is likely to exceed the output limit of the electric motor can be known from the moving distance of the worm.

In the worm mechanism of FIG. 3, a magnet is attached to one end of the worm, and the movement distance of the worm is measured by moving the position of the magnet. For the measurement, a detector (torque sensor) is provided in a groove that extends close to the worm shaft and is parallel to the worm shaft, and the moving distance of the magnet is electrically detected by the torque sensor.

The electrical detector shown in FIG. 3 can also be regarded as a signal generator. That is, when the detected moving distance of the magnet exceeds a certain set value, a signal is electrically generated. The generated signal acts on the switch attached to the second capacitor of the above-mentioned capacitor induction motor to activate the second capacitor. This is the connecting means that links the movement of the worm mechanism to the movement of the capacitor induction motor.

The drive device according to the present invention comprises a capacitor induction motor having the circuit shown in FIG. 2, a speed reducer including the worm mechanism shown in FIG. 3, and connecting means for associating these. is there. This drive device is used by connecting the valve shaft of the valve to the shaft of the worm wheel shown in FIG. By using this drive device, the electric opening and closing of the valve can be smoothly and economically performed. That is, when the drive device is first used, since a large force is not required to open and close the valve, the travel distance of the worm is small, and thus the valve can be opened and closed without operating the second capacitor of the electric motor. it can. Therefore, at this stage, electric power is consumed as usual, which is economical.

However, when the valve is used for a while and a large force is required to open and close the valve body, the movement distance of the worm gradually increases, and the movement distance approaches a certain set value. Then, the detector or signal generator emits a signal to switch on and automatically activate the second capacitor. Then, the electric motor rotates the valve body with a large force. Thus, in the conventional method, the drive device has to be replaced, but according to the device of the present invention, the opening and closing of the valve body can be continued without changing the drive device.

Moreover, since a large force is exerted only when a truly large force is required to rotate the valve element, there is no waste in power consumption and it is economical. .

If the output of the electric motor suddenly becomes insufficient for some reason during the work of opening and closing the valve without operating the second capacitor, the switch is turned on and the second
The output of opening and closing the valve can be easily increased by operating the capacitor, which is convenient because it allows for on-site emergency repairs. The device according to the present invention provides such a benefit.

In the method of the present invention, the capacitor induction motor shown in FIG. 2 and the speed reducer shown in FIG. 3 are related to each other by the connecting means described above, and the output shaft of the speed reducer is connected to the valve shaft. This makes it easy to implement.
That is, in this case, after rotating the rotational force of the capacitor induction motor by the worm mechanism, this rotational force is transmitted to the valve shaft of the valve to open and close the valve, and the capacitor induction motor is normally installed. A circuit including the first capacitor is connected with the second capacitor together with the switch in parallel with the first capacitor, and the valve can be opened and closed by operating the electric motor without operating the second capacitor at first. In addition, when the valve is opened or closed, the worm in the worm mechanism always measures the force required to rotate the worm wheel, and when the force exceeds the set value, the switch automatically operates to activate the second condenser. Can be activated. Thus, the method of the present invention enables smooth and economical opening and closing of the valve electrically. The method of the present invention provides such benefits.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a conventional capacitor induction motor.

FIG. 2 is a circuit diagram of a capacitor induction motor used in the present invention.

FIG. 3 is an explanatory view showing the worm mechanism of the speed reducer used in the present invention and a part of the connecting means.

Claims (5)

[Claims] 1. A method for opening and closing a valve by transmitting the rotational force of a capacitor induction motor to a valve shaft of a valve after decelerating the torque by a worm mechanism, in a circuit including a first capacitor usually attached to a capacitor induction motor,
The second capacitor is connected in parallel with the first capacitor together with the switch. At first, the electric motor is operated without operating the second capacitor to open / close the valve. When the valve is opened / closed, the worm in the worm mechanism rotates the worm wheel. It is characterized in that the magnitude of the force required to operate is measured, and when the magnitude of the force exceeds a set value, the switch automatically operates to activate the second capacitor, How to open and close the valve electrically. 2. The magnitude of the force required for the worm to rotate the worm wheel is measured by the distance the worm moves axially against the spring on the worm shaft. Item 2. An electric valve opening / closing method according to Item 1. 3. The position of the magnet fixed to a part of the worm is detected by a detector installed close to the worm shaft,
The method for electrically opening and closing a valve according to claim 2, wherein the moving distance of the worm is measured. 4. The signal generator activates a second capacitor by emitting a signal when the worm travel exceeds a preset value.
Alternatively, the method for electrically opening and closing the valve according to the item 3 is provided. 5. A capacitor induction motor, a speed reducer including a worm mechanism, and connecting means for relating the movement of the worm mechanism to the movement of the capacitor induction motor. The capacitor induction motor is usually equipped with a first unit. The second capacitor is connected to the circuit including the capacitor in parallel with the first capacitor together with the switch. In the above worm mechanism, the worm is capable of moving on the worm shaft against the spring and the above means is provided. An electrically-operated valve opening / closing device, characterized in that when the moving distance of the worm on the worm shaft exceeds a certain set value, the switch operates to actuate the second capacitor.