JP5315972B2 - Shut-off valve - Google Patents

Description

  The present invention relates to a spring return type electric shut-off valve, and more particularly to a shut-off valve which maintains an open state by controlling a spring winding induction motor in place of an electromagnetic clutch for braking.

The spring return type electric shut-off valve generally has a mechanism as schematically shown in FIG.
In other words, the shut-off valve has a structure in which the output shaft 1 and the motor 2 are connected via a transmission mechanism 3 in which a plurality of gears are combined. Hereinafter, the spring 4 is provided. Incidentally, a torsion spring can also be used for the spring 4.

  A spur gear is attached to the output shaft 1, and a valve 5 is attached to the tip of the output shaft 1, which is below the spur gear in FIG. Further, two cams are attached to the rear end of the output shaft 1 above the spur gear with a phase difference of 90 °, and limit switches 7a and 7b are attached as shown in FIG. Can be detected.

  The motor 2 has a DC or AC motor motor shaft attached with a reduction gearhead and a braking electromagnetic clutch / brake 8 mounted thereon. The motor shaft is slid by the clutch / brake 8 to pinion. The gear head to which the gear is attached is engaged with the transmission mechanism 3 or the motor shaft is fixed and locked.

  The transmission mechanism 3 is a combination of transmission gears having different pitches. By using such a gear, a required torque can be obtained, and a transmission gear engaged with the output shaft 1 (FIG. 6). Then, a spring 4 is attached to the third motor 2). The spring 4 is attached so as to urge the output shaft 1 in the direction in which the valve 5 is closed, and a gear is attached to the rear end of the output shaft 1 to which the spring 4 is attached. Then, a gear with a cam attached is engaged with the rear end gear, and the limit switch 9 engaged with the cam detects that the spring 4 has been wound.

  In such a shut-off valve, when the motor 2 is operated and the valve 5 of the output shaft 1 is opened, the spring 4 provided in the transmission mechanism 3 that rotates the output shaft 1 is also taken up simultaneously. When the limit switch 7a, 7b detects that the valve 5 is open and the limit switch 9 detects that the spring 4 has been wound, the electromagnetic clutch / brake 8 is actuated to activate the motor shaft. Is stopped and the power supply to the motor 2 is stopped. Then, the valve 5 is held in an open state, and the spring 4 is held in a wound state.

  On the other hand, when the energization of the electromagnetic clutch / brake 8 is interrupted in an emergency such as a power failure, the electromagnetic clutch / brake 8 is unlocked and the spring 4 is extended. As a result, the gear of the transmission mechanism 3 is rotated by the extension of the spring 4, and the shutoff valve is closed by rotating the output shaft 1 in the direction in which the valve 5 is closed.

  By the way, in said shut-off valve, in order to close valve 5 quickly at the time of emergency, the thing with big extension force is used for the spring 4. FIG. For this reason, the electromagnetic clutch / brake 8 needs to have a large torque in order to hold the wound spring 4. However, since the thing of a big torque is very expensive, the clutch of a small torque is used using the transmission mechanism 3 for the above deceleration. As a result, the clutch rotates at a very high speed (tens of thousands of revolutions / minute), which causes a problem that causes a failure.

  As one method for solving such a problem, Patent Document 1 describes that the motor 2 is always operated to apply a rotational force so that the spring 4 does not extend and the electromagnetic clutch / brake 8 is not used. Has been.

  That is, this shut-off valve is provided with a power transmission mechanism between the ball valve and the DC motor, and the ball valve is provided with a spring that biases the valve in the closing direction. 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. Then, a circuit as shown in FIG. 7 is provided and controlled. As shown in FIG. 7, this circuit includes a parallel circuit in which the intermittent clutch 10 and the DC motor 2 are connected in parallel and a parallel circuit in which a limit switch 11 and a bypass resistor 12 are connected in parallel. The limit switch 11 is for detecting the opening / closing of the valve 5, which is connected to the DC power supply 14 via the relay contact 13.

In this shut-off valve, since the limit switch 11 is on when the valve is opened, when the relay contact 13 is closed, power is supplied from the DC power source 14 to the motor 2 and the clutch 10. Therefore, the clutch 10 is operated to connect the motor 2 and the gear reduction mechanism, and the motor 2 rotates the ball valve in the valve opening direction via the gear reduction mechanism (against the spring). When the ball valve is opened, the limit switch 11 is turned off, so that the holding current is supplied to the motor 2 and the clutch 10 via the bypass resistor 12. For this reason, the motor 2 keeps the valve open state against the reverse torque caused by the spring of the ball valve by the holding current. On the other hand, when the relay contact 13 is turned off while the valve is open and the supply of power from the DC power supply 14 is interrupted, the clutch 10 disconnects the motor 2 from the gear reduction mechanism, so that the ball valve is rotated by a spring. It will be moved and closed.
Japanese Patent Laid-Open No. 2005-20967

However, in the above, a bypass resistor is connected after the valve is opened, and the voltage applied to the DC motor is lowered to hold the valve. By doing so, the rotational speed of the DC motor is reduced to lower the torque, and the burden on the valve is reduced. The power consumption, noise, and heat generation are reduced.

  However, since a DC motor uses a brush or a commutator, it is more likely to cause a failure than an induction motor that does not use a brush or a commutator, and is inferior in durability. For this reason, there is a problem that regular maintenance is necessary and costly. In particular, the shut-off valve must operate without fail in an emergency, so we want to use a highly reliable induction motor.

  However, if rotation is controlled using an induction motor so as to balance the restoring force of the spring (force to return), the motor is locked, a large current flows and power loss increases. In addition, such a locked state may have a problem that the load on the mechanism portion increases.

  Furthermore, in the above-mentioned, since the connection between the motor and the gear mechanism is cut by the clutch and a sudden closing operation is performed, there is a problem that a water hammer is generated and the shut-off valve is damaged.

  Accordingly, an object of the present invention is to make it possible to use a highly reliable induction motor as a shut-off valve. It is also possible to prevent the occurrence of a water hammer at the deadline.

  In order to solve the above problems, in the present invention, an output shaft connected to a valve and a DC motor are connected via a transmission mechanism that combines a plurality of gears, and a spring that biases the valve in a closing direction and a brake In a shutoff valve provided with an electromagnetic clutch / brake, the motor is an induction motor instead of the electromagnetic clutch / brake for braking, and includes a DC power source and an AC power source, and the DC power source or the AC power source and the induction motor Switch means for switching the connection between the induction motor and the AC power supply when the valve is opened to open the valve, and when the valve is opened, the induction motor and the DC power supply are connected to maintain the open state. The configuration was adopted.

  By adopting such a configuration, when the valve is opened, the switch means connects the AC power source and the induction motor to open the valve at the rated output. After the valve is opened, the switch means connects the DC motor to the induction motor instead of the AC power source, and supplies the DC power. In this way, after the valve is opened, the stator coil of the motor is used as an electromagnet, and the rotor is attracted to keep the valve open.

  Further, at this time, a constant current circuit unit is provided between the induction motor and the ground or between the DC power source and the induction motor, and the constant current circuit is connected to the motor when the switch means connects the induction motor and the DC power source. It is possible to adopt a configuration in which it is interposed between the ground or between the DC power source and the motor.

  By adopting such a configuration, a constant current is supplied to the stator coil having a low impedance so that the attracting force can be maintained. At the same time, the supply current is kept constant to prevent the DC power supply from being overloaded.

  In addition, the DC power supply is provided with battery means, and the constant current circuit is provided with current setting means so as to set a current for maintaining the valve open state and a current for setting the valve closing speed. be able to.

  By adopting such a configuration, a direct current is supplied to the stator coil from the battery means provided in the direct current power source in the event of an emergency such as a power failure, and the sudden closing operation of the valve is prevented by the adsorption force of the stator coil. At this time, the current supplied by the constant current circuit is set by the current setting means to adjust the attracting force, whereby the valve can be closed at the highest speed at which no water hammer is generated.

  Since the present invention is configured as described above, a highly reliable induction motor can be used as the shutoff valve. In addition, the occurrence of a water hammer when the valve is closed can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, this type of shut-off valve is the same as the prior art shown in FIG. The mechanism is the same.

  That is, as shown in FIG. 1, the output shaft 1 and the motor 20 are connected via a transmission mechanism 3 in which a plurality of gears are combined, and the transmission mechanism 3 includes an urging (spring) 4. ing.

  Further, a spur gear is attached to the output shaft 1, and a valve 5 is attached to the tip of the output shaft 1 below the spur gear. On the other hand, at the rear end of the output shaft 1 above the spur gear, two cams are attached with a phase difference of 90 °, and limit switches 7a and 7b are attached so that the opening / closing of the valve 5 can be detected.

  In this embodiment, the motor 20 uses a capacitor-type single-phase AC induction motor as shown in FIG. The motor 20 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 is inserted into the auxiliary winding Lb. It has a structure.

  A gear head is attached to the motor shaft of the motor 20, and a pinion gear is attached to the rotation shaft of the attached gear head so as to engage with the transmission mechanism 3. Therefore, the motor shaft and the output shaft 1 are directly connected via the transmission mechanism 3.

  The transmission mechanism 3 is configured to obtain a required torque by combining transmission gears having different pitches, and the above-described spring 4 is attached to the transmission gear (third from the motor) engaged with the output shaft 1. It is attached. The spring 4 biases the output shaft 1 in the direction in which the valve 5 is closed. Further, a gear is attached to the rear end of the output shaft 1 to which the spring 4 is attached, and the gear to which the cam is attached is engaged to detect that the limit switch 9 has finished winding the spring 4.

  As shown in FIG. 2, the control circuit includes an AC power source 21, a DC power source 22, a constant current circuit unit 23, and a switch unit 24. The constant current circuit unit 23 includes a current setting unit 25. ing.

  The AC power source 21 is an AC 100V power source for a power line, and is connected to the DC power source 22 as shown in FIG. 2 and is connected via the transfer contact circuits RL1-1 and RL1-3 of the relay RL1 serving as the switch means 24. The motor 20 is connected.

The main winding La and the auxiliary winding Lb of the motor 20 are connected to the discharging resistor via the transfer contact circuit RL1-2 of the relay RL1 of the switch means 24.
That is, here, as shown in FIG. 2, the auxiliary winding Lb is connected to the c (transfer) contact of the transfer contact circuit RL1-2, and the b (normally closed) contact is connected to one end of the main winding La. The other end is connected.

The DC power source 22 includes a rectifier circuit 30, a capacitor charging circuit 31, and a DC / DC converter circuit 32, and is connected to the motor 20 via a transfer contact circuit RL1-1 of a relay RL1 that is a switch means 24.
Specifically, the output of the DC / DC converter circuit 32 of the DC power supply 22 is connected to the b contact of the transfer contact circuit RL1-1.

  The rectifier circuit 30 is, for example, a known circuit composed of a step-down transformer, a rectifier bridge circuit, and a smoothing capacitor, and may include a constant voltage circuit or a charging constant current circuit. Here, 12 V smoothed direct current is supplied to the relays RL1 and RL2 of the switch means 24 and also supplied to the capacitor charging circuit 31.

  The capacitor charging circuit 31 is a charging circuit provided with an electric double layer capacitor as battery means, and is connected to the rectifier circuit 30 so as to keep a charged state at all times. In addition, power is supplied to the load during charging.

  The DC / DC converter circuit 32 is configured by, for example, a self-excited up-converter (simple circuit configuration and high reliability) that operates with power supplied from the capacitor charging circuit 31, and the output voltage of the capacitor charging circuit 31 is The voltage is raised to the operating voltage Vc and supplied to the b-contact of the relay RL1 of the motor 20, the constant current circuit unit 23 and the switch means 24. Thus, the use of the electric double layer capacitor as the battery means achieves both long life and maintenance-free.

The capacitor charging circuit 31 may be, for example, a secondary battery such as a lead storage battery or a lithium ion battery as long as it can supply power during a power failure. It is also possible to use a primary battery that cannot be charged.
Furthermore, the configuration of the DC power supply 22 can be realized even without using the DC / DC converter circuit 32 as long as the output voltage of the rectifier circuit 30 and the output voltage of the charging circuit 31 can be set to be the same as the operating voltage Vc.

The constant current circuit unit 23 is provided between the motor 20 and the ground via a transfer contact circuit RL1-3 of the relay RL1 of the switch means 24.
Specifically, as shown in FIG. 2, it is connected to the b contact of the transfer contact circuit RL1-3, and is connected to the motor 20 by switching the transfer contact circuit RL1-3.

  This constant current circuit unit 23 uses an N-channel junction type FET 35 and an operational amplifier 36, and connects the connection point between the source terminal of the FET 35 and the resistor 37 to the inverting input of the operational amplifier 36, and the non-inverting input of the operational amplifier 36. The current setting means 25 is connected to this. The operational amplifier 36 compares the voltage drop Vs of the resistor 37 whose one end is grounded with the set voltage of the current setting means 25, and controls the current by operating the FET 25 so that they are equal.

  As shown in FIG. 2, the current setting means 25 includes two semi-fixed volumes VR1 and VR2 and a transfer contact circuit RL2-1 of a relay RL2 (switch means 24).

The semi-fixed volume VR1 is for adjusting a torque for holding the valve 5 in an open state (after winding of the spring 4). The semi-fixed volume VR2 is for adjusting the shut-off speed when the valve is closed in an emergency.
The semi-fixed volumes VR1 and VR2 have one end connected to the output of a DC power source (DC / DC converter) 22 and the other end grounded. The outputs of the volumes VR1 and VR2 are connected to the a contact and the b contact of the transfer contact circuit RL2-1 of the relay RL2, respectively.

  As described above, the transfer contact circuit RL2-1 of the relay RL2 connects the contact a with the output of the volume VR1, connects the point b with the output of the volume VR2, and connects the contact c with the non-inverting input of the operational amplifier. Thus, the input to the operational amplifier is switched by the operation of the relay RL2, and the current value of the constant current circuit unit 23 can be changed.

The switch means 24 is composed of two relays RL1 and RL2. The relay RL1 has three transfer contact circuits RL1-1, RL1-2, and RL1-3, and is connected to the output of the rectifier circuit 30 via the limit switch 9 as shown in FIG.
Here, the limit switch 9 uses a normally closed contact to detect the winding (winding) of the spring 4 described above in the transmission mechanism 3.
Therefore, when the limit switch 9 detects the winding of the mainspring 4 and operates, the switch output is turned off, and the transfer contact circuits RL1-1, RL1-2, and RL1-3 of the relay RL1 move from the a contact to the b contact. .
On the other hand, the relay RL2 is connected to the output of the rectifier circuit 30, normally maintains the ON state at the output of the rectifier circuit 30 connected to the AC power source 21, and the input from the AC power source 21 is interrupted due to a power failure or the like. It is supposed to be off.

This embodiment is configured as described above, and the shut-off valve adjusts the semi-fixed volume VR1 of the current setting means 25 in operation, and holds the valve 5 with the spring 4 wound up as described above. Set the current. Further, the semi-fixed volume VR2 is adjusted to set a current for adjusting the valve closing speed in an emergency. Since both volumes VR1 and VR2 differ depending on the shape of the shutoff valve and the installation conditions thereof, it is preferable that the volumes VR1 and VR2 are appropriately set according to the environment, for example, by cut and try.
At this time, the current for setting the shutoff speed of the volume VR2 is sufficiently lower than the current for setting the stop torque at the time of winding the volume VR1, so that the torque can be lowered to start the valve closing.

When the setting is completed and the AC power supply 21 is turned on, power is supplied from the rectifier circuit 30 to the relays RL1 and RL2 of the switch means 24 and the capacitor charging circuit 31.
At this time, since the spring 4 is in the extended state, the limit switch 9 is off, but the output of the normally closed contact is on. Therefore, the relay RL1 of the switch means 24 is turned on, and the transfer contact circuits RL1-1, RL1-2, RL1-3 of the relay RL1 are connected as shown in FIG. 3, and the AC power source 21 and the motor 20 are connected. Connected.
As a result, the motor 20 rotates the output shaft 1 via the transmission mechanism 3 and opens the valve. At the same time, the spring 4 of the transmission mechanism 3 is wound up.

  At this time, since the relay RL2 is turned on by the output of the rectifier circuit 30, the transfer contact circuit RL2-1 provided in the current setting means 25 is in a standby state in a state where it is moved (connected) to the a contact. .

  On the other hand, when power is supplied from the rectifier circuit 30, the capacitor charging circuit 31 operates the DC / DC converter circuit 32 to boost the operating voltage to the contact b of the transfer contact circuit RL 1-1 and the constant current circuit unit 23. Supply power.

  In this state, when the valve 5 is opened, the spring 4 is wound up and the limit switch 9 is turned on, the normally closed contact output of the switch 9 is turned on, the relay RL1 of the switch means 24 is turned off, and the relay RL1. Each of the transfer contact circuits RL1-1, RL1-2, and RL1-3 moves from the a contact to the b contact. Therefore, as shown in FIG. 4, a DC power source (DC / DC converter) 22 is connected to the motor 20, and at the same time, a constant current circuit unit 23 is connected between the motor 20 and the ground. The main winding La and the auxiliary winding Lb of the motor 20 are connected in parallel through a resistor (for short circuit prevention). Therefore, the motor 20 is supplied with the DC current set by the volume VR1 of the current setting means 25 from the DC power supply 22.

  That is, the direct current set by the constant current circuit unit 23 is supplied to the main winding La and the auxiliary winding Lb of the stator coil of the motor 20. When this direct current is supplied to the stator coils La and Lb, the coils La and Lb become electromagnets to attract the rotor. The adsorbed rotor holds the valve open state against the extension force of the spring 4.

  As described above, since the current is supplied using the constant current circuit unit 23 after the valve is opened, the stator coil La having a low impedance can be obtained without overloading the DC power source (mainly DC / DC converter) 22. And Lb can be supplied with a holding current.

After that, when an abnormality such as a power failure occurs and the AC power supply 21 is shut off, the output of the rectifier circuit 30 disappears. Therefore, the relay RL1 of the switch unit 24 maintains the off state regardless of whether the limit switch 9 is on or off. On the other hand, the relay RL2 is turned off from on.
That is, the transfer contact circuits RL1-1, RL1-2, and RL1-3 of the relay RL1 maintain the b contact. On the other hand, the transfer contact circuit RL2-1 of the relay RL2 moves to the b contact side as indicated by the broken line in FIG.
Accordingly, the output of the current setting means 25 is changed from the stop torque set by the volume VR1 to the setting of the cutoff speed set by the volume VR2. Therefore, the holding current is reduced by the constant current circuit unit 23, and the attractive force is reduced. As a result, the extension force of the spring 4 becomes dominant and the valve closing operation is started. At this time, since the valve closing speed is decelerated by the current set by the volume VR2, a sudden closing operation is not performed. Thus, if the set current is adjusted optimally, the valve can be closed at the highest speed so that a water hammer does not occur.

  As described above, the highly reliable induction motor 20 can be used as the shut-off valve, and the load applied to the valve 5 can be reduced by maintaining the valve open state with a circuit having a simple configuration. Therefore, it is not necessary to use expensive clutches and brakes.

  In this embodiment, the constant current circuit unit 23 is provided between the motor 20 and the ground, but the present invention is not limited to this. For example, even if the constant current circuit unit 23 is provided between the DC power supply 22 and the motor 20 as shown in the figure, the same effect as the embodiment can be obtained.

Structure diagram of the embodiment Circuit block diagram of the embodiment Action explanatory diagram of the embodiment Action explanatory diagram of the embodiment Action explanatory drawing which shows the other aspect of embodiment Structure diagram of conventional example Circuit diagram of conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Output shaft 2 DC motor 3 Transmission mechanism 4 Spring 5 Valve 8 Electromagnetic clutch / brake 20 Induction motor 21 AC power source 22 DC power source 23 Constant current circuit part 24 Switch means 25 Current setting means 31 Battery means

Claims (1)

A spring (1) that connects the output shaft (1) connected to the valve (5) and the DC motor (2) via a transmission mechanism (3) that combines a plurality of gears, and biases the valve (5) in the closing direction. 4) and an electromagnetic clutch / brake (8) for braking, actuating the motor (2) to open the valve (5) while winding the spring (4), and when the valve (5) opens, After actuating the electromagnetic clutch / brake (8), turn off the motor (2), hold the valve (5) open, and close the valve (5) with the urging force of the spring (4) in an emergency. In the shut-off valve
Instead of the electromagnetic clutch and brake (8) for the brake, when the above-mentioned motor (2) the induction motor (20) and monitor, equipped with a DC power supply (22) and an AC power source (21), the DC power supply ( 22) or switch means (24) for switching the connection between the AC power source (21) and the induction motor (20). When the switch means (24) opens the valve, the induction motor (20) and the AC power source (21) are switched. opening the valve (5) connected to the valve (5) shut-off valve for holding an open state by connecting a DC power source (22) and opens the induction motor (20), and the induction motor (20) A constant current circuit unit (23) is provided between the ground or between the DC power source (22) and the induction motor (20), and the switch unit (24) is connected to the induction motor (20) and the DC power source. When connecting (22), the mode (20) and ground or between the DC power supply (22) and the motor (20), the DC power supply (22) includes battery means (31), and the constant current circuit section ( 23) A shut-off valve provided with a current setting means (25) in 23) to set a current for maintaining the open state of the valve (5) and a current for setting the valve closing speed.

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