JPH08145220A - Control method for electrically-driven flow rate control valve - Google Patents

Abstract

PURPOSE: To eliminate malfunction accompanied with excessive fastening of a screw with a simple structure in a device where rotation of a motor is transduced to reciprocation of a valve through a screw mechanism by rotating the motor is rotated with high torque with a specified time from starting, and rotating it with low torque in other time. CONSTITUTION: A valve body 4 in a casing 1 is provided with an external screw 5 screwed with an internal screw 3 formed on the casing 1, and a guide groove 7 to which a pin 10 embedded on a shaft 9 of a stepping motor 8 is fitted. By the rotation of the motor 8, torque is transmitted to a valve body 4 through the pin 10, so that the external screw 5 is screwed with the internal screw 3, for reciprocating the valve body 4. In such a control method for an electrically-driven flow rate control valve, in order to open the valve body 4, the motor 8 is rotated with high torque within a set time from starting. The motor 8 is rotated with a low torque after specified time passes until the completion of opening the valve, and from the opening state to the closing state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling an electric flow control valve which converts the rotation of a motor into a forward / backward movement of a valve via a screw mechanism.

[0002]

2. Description of the Related Art In an electric flow control valve that converts the rotation of a motor into a forward / backward movement of a valve via a screw mechanism, the motor continues to rotate despite the valve being pressed against a port. When the torque is continuously applied, the screw mechanism is excessively tightened, and in order to turn the tightened screw in the opposite direction to loosen it, a torque larger than the tightened torque is required.

Such excessive screw tightening occurs not only in the final stage of valve closing but also in the final stage of valve opening. In either case,
If the torque required for loosening cannot be applied, the valve cannot be moved, which may cause troubles such as opening or closing the valve. In order to prevent such inconvenience, it is necessary to attach an element such as a valve position detecting device to prevent the screw from being tightened, or to provide a mechanism for loosening the screw after it is tightened.

[0004]

SUMMARY OF THE INVENTION The present invention eliminates excessive screw tightening at the final stage of valve closing and the final stage of valve opening, which leads to an increase in cost and a valve position detecting device, and a tightened valve position detecting device. Another object of the present invention is to provide a control method means for an electric flow control valve that does not require a special mechanism for loosening the valve.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for controlling an electric flow control valve of the type in which rotation of a motor is converted into forward / backward movement of a valve via a screw mechanism, and a valve in a closed state is opened. At the time of starting, the motor is rotated with a high torque within a set time from the start, and after the predetermined set time when the other valves in the valve closed state are opened and after completion of the valve opening,
The motor is rotated with a low torque during the period from the open state to the closed state.

Further, according to the present invention, in the control method of the electric type flow control valve of the type in which the rotation of the step motor is converted into the forward / backward movement of the valve through the screw mechanism, when the valve in the closed state is opened, The step motor is rotated with a high torque during the set time from the start, and after the predetermined set time elapses when the other valves that are in the valve closed state are opened, the valve is opened, and the valve is opened. While the valve is closed, the step motor is rotated with a low torque, and the valve closing position of the step motor is used as a starting point, and the valve position when opening the valve is regulated by the number of steps or the motor rotation angle from the starting point. It is the one.

Further, according to the present invention, the valve position is regulated when the valve is opened by mechanically bringing the valve into contact with the locking means, and the valve opening position is used as a starting point, and the number of steps or the motor rotation from the starting point. The above torque control is performed depending on the angle.

[0008]

[Operation] According to the present invention, the valve in the closed state can be surely opened by selecting the motor that can obtain the torque required to loosen the screw. Other than that, the torque is lower than the above torque during the period from the open state to the closed state and after the elapse of a predetermined set time when the valve in the closed state is opened to the completion of the valve opening. Therefore, excessive tightening of the screw at the time of opening the valve does not occur.

If the above motor is a step motor,
In order to rotate exactly by the rotation angle determined by the number of input pulses, position regulation is performed by giving a pulse that you want to rotate, in other words, a predetermined time or angle, step without requiring position detection or comparison. Is possible. Therefore, when the valve is closed, the position of the valve from that point can be known from the given number of steps or rotation angle. It is possible to control by stopping with.

Further, if the valve position is regulated when the valve is opened by mechanically bringing the valve into contact with the locking means, accurate regulation is possible. From the valve opening position as a starting point, the number of steps from that starting point is set. Alternatively, the torque control described above may be performed depending on the motor rotation angle.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing the operating principle in the valve opening process of the present invention, in which the vertical axis represents the torque T obtained by the motor and the horizontal axis represents time. Conventionally, as indicated by the alternate long and short dash line, the torque is constant from the time the motor starts rotating to the time it stops.

On the other hand, in the present invention, as indicated by the solid line, the torque is high from point A at the start of valve opening to point B after the elapse of a predetermined set time, but after reaching point B, the torque is low. There is no point C, and there is a difference in that the above-mentioned low torque is maintained from point C to point D when stopped. The high torque at the start of valve opening can be determined from the point that it can be loosened even if excessive screw tightening occurs, and if it is determined, a motor that can generate the high torque can be selected. It will be good. The torque lower than the high torque can be achieved by adjusting the power supply applied to the excitation winding.

If the motor is a stepping motor that rotates by rotating a rotor made of a permanent magnet with an electromagnetic force generated by a stator winding, the motor can be accurately rotated by a rotation angle determined by the number of input pulses. it can. Therefore, the valve position can be regulated from the starting point by deciding the starting point as the A point and giving a pulse as many as desired to rotate.

There is no reason why the above-mentioned starting point must be the A point, and the D point may be the starting point. To determine the point D, the valve is mechanically brought into contact with the locking means, and accurate valve position regulation is performed.
Point to point C and point B to point A can be determined by the time, the number of steps, or the rotation angle, respectively.

An example of an electric type flow control valve of the type in which the rotation of the motor is converted into the forward / backward movement of the valve via a screw mechanism is shown in FIG.
Shown in

In the figure, 1 is a casing of the flow control valve, 2 is its port, and the arrows show the flow of fluid. An outer threaded portion 5 that is screwed into an inner threaded portion 3 formed in the casing 1 and a pin 10 that is planted on a shaft 9 of a stepping motor 8 are fitted into the valve body 4 that is internally and movably installed in the casing 1. A guide groove 7 is formed so as to fit therewith. still,
Reference numeral 6 is an O-ring provided for maintaining liquid tightness between the inner surface of the casing 1 and the outer surface of the valve body 4. When the rotational force is transmitted to the valve body 4 via the pin 10 by the rotation of the stepping motor 8, the outer screw portion 5 is screwed into the inner screw portion 3 of the casing 1. Can be moved back and forth. In this example, when the end surface of the guide groove 7 comes into contact with the pin 10, the valve body 4 is not retracted any further.

In the example of FIG. 2, the shaft 9 of the stepping motor 8 is used.
Although no thrust load is applied to the screw, if such consideration is unnecessary, a screw member 11 is attached to the shaft 9 of the stepping motor 8 as shown in FIG.
It is also possible to have a structure in which the locking means 14 attached to the casing 1 is fitted in the guide groove 13 formed on the valve body 4 side by screwing together the inner threaded portion 12 formed on the valve body 4. In this way, the flow control valve has a simple structure.

[0018]

As described above, according to the present invention,
In order to eliminate the inconvenience caused by excessive tightening of screws, it is extremely effective in that it is not necessary to provide an extra device such as a valve position detecting device, and the cost and size can be reduced.

Further, the motor is a step motor, and the valve closing position is used as a starting point, and the valve position when opening is regulated by the number of steps or the rotation angle from the starting point. When the valve is fully opened, excessive screw tightening is performed. It is possible to easily control that the valve is stopped just before that, and excessive tightening of screws at the time of valve opening does not occur.

Further, the valve position at the time of opening the valve is regulated by mechanically abutting the locking means on the valve, and the valve opening position is used as a starting point, and the number of steps from the starting point or the motor rotation angle is used for the above description. When performing the torque control, if the valve must not be completely closed or if it is not necessary to completely close the valve, the control becomes easy.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between torque and time for explaining a control method of an electric flow control valve according to the present invention.

FIG. 2 is a cross-sectional view showing the structure of an electric flow control valve used in the control method of the present invention.

FIG. 3 is a cross-sectional view showing the structure of an electric flow control valve different from that of FIG.

[Explanation of symbols]

 1 ... Casing of flow control valve 2 ... Port 3 ... Inner thread 4 ... Valve body 5 ... Outer thread 6 ... O-ring 7 ... Guide groove 8 ... Stepping motor 9 ... Shaft 10 ... …pin

Claims (3)

[Claims] 1. A control method for an electrically operated flow control valve, wherein a rotation of a motor is converted into an advancing / retreating motion of a valve via a screw mechanism, and when a valve in a closed state is opened, within a set time from start-up. Is the rotation of the motor with a high torque and the opening of other valves in the closed state after a predetermined set time has elapsed and the valve has been opened, and the valve has been opened and closed. Is a method for controlling an electric flow control valve, characterized in that the motor is rotated with a low torque. 2. A control method for an electrically operated flow control valve, wherein a rotation of a step motor is converted into a forward / backward movement of a valve via a screw mechanism, and when a valve in a closed state is opened, a set time is set from start-up. The inside of the valve is changed from the open state to the closed state after the predetermined set time elapses when the step motor is rotated with high torque and the other valves in the closed state are opened. During this period, the step motor is rotated with a low torque, the valve closing position of the step motor is used as a starting point, and the valve position at the time of valve opening is regulated by the number of steps or the motor rotation angle from the starting point. Electric flow control valve control method. 3. The valve position regulation at the time of valve opening is performed by mechanically bringing the valve into contact with the locking means, and the valve opening position is used as a starting point, and the above-mentioned value is determined by the number of steps or the rotation angle from the starting point. 2. Torque control is performed.
Alternatively, the control method of the electric flow control valve according to claim 2.