JP2011007251A - Power-saving circuit of motor-operated valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To save energy, by reducing worthless heat generation in a spring-return type valve, and to elongate the lifetime.SOLUTION: A reactance element 11 is connected to between an alternator 13 and an induction motor 10 driving a valve in a direction opening the valve against a spring via a switch means 12. When the valve is opened, the alternator 13 is connected with the induction motor 10 to open the valve and thereby to compress the spring. After the valve is opened, the reactance element 11 is connected to between the alternator 13 and the motor 10 through the switch means 12 to decrease voltage applied to the motor 10 and thereby to decrease torque of the motor 10. The electric power is not consumed since a phase difference between a current flowing in the reactance element 11 and the voltage becomes π/2, so that the heat generation is suppressed to save energy.

Description

  The present invention relates to a power saving circuit for a motor-operated valve for reducing the holding power of a shut-off valve.

  The spring return type electric shut-off valve applies a rotational force by always operating a motor, and keeps the valve open so that the spring does not extend. In this way, when power is stopped in an emergency, the spring extends to close the valve.

For example, the shut-off valve shown in Patent Document 1 has a configuration in which a power transmission mechanism is provided between a ball valve and a DC motor, and a spring that biases the ball valve in a direction to close the valve is provided.
Here, the power transmission mechanism is composed of an electromagnetic clutch and a gear reduction mechanism, and the clutch is merely for connecting and disconnecting the motor and the gear reduction mechanism. A circuit as shown in FIG. 6 is provided and controlled. As shown in FIG. 6, this circuit includes a parallel circuit in which the intermittent clutch 1 and the DC motor 2 are connected in parallel and a parallel circuit in which a limit switch 3 and a bypass resistor 4 are connected in parallel. The limit switch 3 is provided for detecting the opening / closing of the valve.

In this shut-off valve, since the limit switch 3 is on when the valve is opened, when the relay contact 5 is closed, power is supplied from the DC power source 6 to the DC motor 2 and the clutch 1. Therefore, the clutch 1 is operated to connect the DC motor 2 and the gear reduction mechanism, and the motor 2 rotates the ball valve in the valve opening direction (against the spring) via the gear reduction mechanism. When the ball valve is opened, the limit switch 3 is turned off, so that electric power is supplied to the motor 2 and the clutch 1 via the bypass resistor 4. Therefore, the torque of the DC motor 2 whose current is limited by the bypass resistor 4 is limited.
At this time,
Spring restoring force <DC motor hoisting force, and the motor 2 keeps the valve open state against the reverse torque caused by the spring of the ball valve.
On the other hand, when the relay contact 5 is turned off while the valve is open and the supply of power from the DC power supply 6 is interrupted, the clutch 1 disconnects the DC motor 2 from the gear mechanism, so that the ball valve is closed by a spring. It turns in the valve direction and closes.

Japanese Patent Laid-Open No. 2005-20967

  However, in the above circuit, since the current of the DC motor is controlled by the bypass resistor, the resistor generates heat. At this time, since the motor-operated valve has a sealed structure, the internal temperature rises, for example, the dielectric breakdown of the motor coil occurs due to the temperature rise, the lubricating oil evaporates and the friction coefficient increases, This will shorten the life of the motor and mechanism.

  Accordingly, an object of the present invention is to reduce wasteful heat generation and save energy, and at the same time, to extend the life.

  In order to solve the above problems, in the present invention, a valve, a spring that biases the valve in a closing direction, an induction motor that drives the valve in a direction to open the valve against the spring, and between the motor and an AC power source A reactance element connected via a switch means to the motor, an AC power supply is connected, the motor is driven to open a valve while compressing a spring, and when the valve is opened, the switch means A configuration was adopted in which a reactance element was connected between the motor and the AC power supply to keep the valve open.

  With this configuration, when the valve is opened, the valve is opened by connecting the AC power source and the induction motor, and at the same time, the blocking spring is compressed. After the valve is opened, only the extension of the spring is stopped. Therefore, a reactance element is connected between the AC power source and the motor by the switch means, and the voltage applied to the motor is lowered to lower the torque of the motor. At this time, since the phase difference between the current flowing through the reactance element and the voltage is π / 2, power is not consumed. Therefore, heat generation can be suppressed and energy saving can be achieved.

  Further, at this time, it is possible to adopt a configuration in which an adjustment resistor is provided in series with the reactance element so that the torque can be adjusted.

  By adopting such a configuration, it is possible to adjust the torque by adjusting the voltage applied to the motor with the adjusting resistor.For example, the torque variation can be adjusted for each individual shutoff valve. The torque can be adjusted so that it can be used optimally even in regions with different power supply frequencies.

  Further, at this time, instead of the adjustment resistor, a configuration in which a bidirectional thyristor is provided so that the torque can be adjusted can be employed.

  By adopting such a configuration, the voltage can be adjusted by phase control, so that the power loss due to the adjusting resistor can be reduced.

  Since the present invention is configured as described above, power consumption can be reduced, wasteful heat generation can be reduced, and the life can be extended. In addition, energy saving can be achieved.

(A) Circuit diagram of embodiment, (b) Diagram showing another mode of switch means Action explanatory diagram of shut-off valve of embodiment Circuit diagram of Example 1 Circuit diagram of Example 2 Circuit diagram of Example 3 Circuit diagram of conventional example

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
A power saving circuit of the motor-operated valve of this embodiment is shown in FIG. As shown in FIG. 1A, the power saving circuit of this embodiment includes a single-phase induction motor 10, a reactance element 11, and a switch means 12, and is connected to an AC power source 13.

  The single phase induction motor 10 uses a capacitor starting type. The motor 10 is a cage-shaped rotor in which a stator coil composed of a main winding La and an auxiliary winding Lb is arranged orthogonally. Here, a phase advance capacitor Ca is provided on the auxiliary winding Lb. It has an inserted structure.

  Further, as shown in FIG. 2, for example, the motor 10 has a structure that is connected via an output shaft 15 of the valve 14 and a transmission mechanism 16 that combines a plurality of gears. A (spring) spring 17 is provided.

  At this time, a gear head is attached to the motor shaft of the motor 10, and a pinion gear is attached to the rotation shaft of the attached gear head to be engaged with the transmission mechanism 16. Therefore, the motor shaft and the output shaft 15 are directly connected via a transmission mechanism.

  The transmission mechanism 16 is configured to obtain a required torque by combining transmission gears having different pitches. A direction in which the spring 17 is attached to the transmission gear engaged with the output shaft 15 to close the valve 14. The output shaft 15 is biased.

  On the other hand, a spur gear is attached to the output shaft of the valve 14, and the valve 14 is attached to the tip of the output shaft below the spur gear. Furthermore, a cam is attached to the rear end of the output shaft above the spur gear, and the aforementioned switch means 12 is attached so that the opening / closing of the valve 14 can be detected.

  The switch means 12 uses, for example, a limit switch or a relay operated by a limit switch. When the valve 14 is opened and closed, as shown in FIG. 1A, the normally open contact (a contact) is changed to a normally closed contact. A single pole double throw switch to (b contact) is used. The switching contact (c contact) of the switch means 12 is connected to the main winding La of the motor 10 and the normally open contact (a contact) is connected to the AC power supply 13. The normally closed contact (b contact) is connected to one of the reactance elements 11 so that the reactance element 11 is connected between the motor 10 and the AC power supply 13 when the valve is opened.

In this embodiment, the reactance element 11 is a capacitive element (capacitor C). The capacitor C can be used with an alternating current and has a sufficient withstand voltage.
At this time, the reactance of the capacitor C is
Xc = 1 / ωC (Ω)
Therefore, the capacity is set appropriately so that a torque sufficient to balance the extension force of the spring 17 (for the sake of safety, the extension force of the spring <torque) is obtained. At that time, the capacity includes the coils La and Lb of the motor 10 and the phase capacitor Ca in the circuit, and is calculated based on the above formula in consideration of results of experiments and experiences.

  In the power saving circuit configured as described above, when the valve is opened, since the switch means 12 is set to the a contact, the motor 10 opens the valve 14 while compressing the spring 17 with the rated output. When the valve 14 is opened, the switch means 12 is switched, and the capacitor C is connected between the motor 10 and the AC power supply 13. Therefore, when the voltage applied to the motor 10 is reduced by the inserted capacitor C, the rotational speed of the motor 10 is reduced and the torque is reduced. In addition, the power consumption of the motor 10 is reduced. At this time, since the capacity of the capacitor C is set so that the torque is balanced with the extension force of the spring 17, the valve open state can be maintained. In addition, at this time, the phase of the current flowing through the capacitor C as the reactance element 11 is delayed by π / 2 from the voltage, so that no power loss occurs.

  In this way, the reactance element 11 does not cause a power loss, so that it does not generate heat like a resistor. In addition, since the motor 10 also reduces the torque, heat generation can be reduced. Therefore, useless heat generation can be reduced to extend the life of the shut-off valve, and at the same time energy saving can be achieved.

  In this embodiment, the single-pole double-throw switch unit 12 is used in this embodiment. However, it is sufficient that the reactance element 11 can be connected between the motor 10 and the AC power source 13, and as shown in FIG. A pole throw type can also be used.

In the first embodiment, as shown in FIG. 3, a coil (inductor) L is used as the reactance element 11. The reactance for the coil L is
XL = ωL (Ω)
Since the phase of the current flowing through the coil L advances by π / 2 from the voltage, no power loss occurs.
In addition, the inductor of the coil L is appropriately set so as to obtain a torque that balances with the extension force of the spring 17 (for the sake of safety, the extension force of the spring <torque). At this time, as described above, the circuits include the coils La and Lb of the motor 10 and the phase capacitor Ca, and the calculation is performed based on the above formula, taking into account the results of experiments and experiences. In the circuit, there are a motor coil, a phase capacitor, and the like.
Since other configurations are the same as those of the embodiment, the same reference numerals are given to the drawings and description thereof is omitted.

In the second embodiment, as shown in FIG. 4, an adjustment resistor 18 is provided in series with the reactance element 11. Here, a variable resistor is used as the adjustment resistor 18. Thus, the amplitude of the voltage applied to the motor 10 is adjusted by using the variable resistor 18. The torque is adjusted by adjusting the amplitude of the applied voltage. For example, the variation of the individual valves 14 can be adjusted by adjusting the torque. Further, even when the frequency of the AC power supply 13 is changed from 50 Hz to 60 Hz, adjustment can be performed to set an appropriate torque. Therefore, there is no need to prepare a different specification for each power supply frequency.
At this time, the reactance element 11 does not cause power loss (although power loss occurs in the adjustment resistor 18), it does not generate heat unlike the case of only the resistor. In addition, since the motor 10 also reduces the torque, the heat generation of the motor 10 can be reduced. Therefore, useless heat generation can be reduced, the life of the shut-off valve can be extended, and energy can be saved.
Incidentally, it is conceivable to adjust the reactance element 11 at this time, but, for example, since the types of capacitance values of the commercially available capacitor C are limited, it is easier to perform accurate adjustment by using the adjustment resistor 18. Can be.
In the second embodiment, a variable resistor is used as the adjustment resistor 18. However, a fixed resistor may be used (a resistor having an appropriate resistance value may be attached, or a switch may be provided for switching. .) Obviously, it may be adjusted.

The third embodiment uses a bidirectional thyristor 20 as shown in FIG. 5 in place of the adjustment resistor 18 of the second embodiment, and the phase control circuit 21 controls the amplitude of the voltage applied to the motor 10. It is intended to be adjusted. The torque is reduced by lowering the voltage applied to the motor 10 by phase control in this way.
At this time, since the voltage is lowered by phase control, the resistance loss can be reduced as compared with the case where the adjusting resistor 18 is used. The other functions and effects are the same as those of the first embodiment, and therefore, the same reference numerals are given to the drawings and description thereof is omitted.

In the second and third embodiments, the capacitor C is employed as the reactance element 11, but it is obvious that the coil L may be used.
Moreover, although the embodiment and Examples 1 to 3 described the use of the single-phase induction motor for the induction motor, the present invention is not limited to this. In the case of an induction motor, if the voltage is reduced, the torque can be reduced, so that the present invention can also be applied to a three-phase induction motor.

DESCRIPTION OF SYMBOLS 10 Single phase induction motor 11 Reactance element 12 Switch means 13 AC power supply 18 Adjustment resistance 20 Bidirectional thyristor C Capacitor L Coil

Claims (3)

A valve, a spring that biases the valve in a closing direction, an induction motor that drives the valve in a direction to open the valve against the spring, and a reactance element that is connected between the motor and an AC power source via a switch means Consists of
When the motor is connected to an AC power supply, the motor is driven to open the valve while compressing the spring, and when the valve is opened, the switch means connects the reactance element between the motor and the AC power supply to open the valve. Power saving circuit for motorized valve   The power saving circuit for a motor-operated valve according to claim 1, wherein an adjustment resistor is provided in series with the reactance element so that torque can be adjusted according to a power supply frequency.   The power saving circuit for a motor-operated valve according to claim 2, wherein a torque can be adjusted by providing a bidirectional thyristor instead of the adjusting resistor.

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