JP5711591B2 - Electric emergency shut-off valve - Google Patents

Description

  The present invention relates to an electric emergency shut-off valve that can change the opening degree of a valve.

As a shut-off valve that can change the opening of the valve, for example, there is a four-wire wiring (AC input terminal, open input terminal, and closed input terminal) shown in Patent Document 1. As shown in FIG. 5, the shut-off valve (with the cover case removed) is connected to the opening / closing motor 4 via the reduction gear 3 at the other end of the output shaft 2 to which the valve 1 is attached at one end. Is attached. Further, as shown in FIG. 6, a sleeve 7 having a sun gear 6 attached between the valve 1 and the drive gear 5 is inserted into the output shaft 2, and around the sun gear 6 attached to the lower portion of the sleeve 7. A planetary gear 8 is arranged. Further, the planetary gear 10 is formed by fitting an internal gear 9 having teeth formed inside the ring on the outer side of the planetary gear 8, and a hook-shaped support plate 11 is provided below the sleeve 7 to The planetary mechanism 10 is supported.
On the other hand, a circular plate 12 and a fan-shaped gear 13 are attached to the upper portion of the sleeve 7. The fan-shaped gear 13 has teeth formed around the fan-shaped periphery, and is mounted on the circular plate 12 as shown in FIG. 6, and a pin 14 provided on one side of the mounted fan-shaped gear 13 on the circular plate 12. To come in contact with. The circular plate 12 and the support plate 11 are connected by a connecting shaft 15 through which the planetary gear 8 is inserted, and the sector gear 13 on the circular plate 12 meshes with a winding gear 17 attached to a spring spring 16. doing. The winding gear 17 meshes with the pinion gear of the spring winding motor 19 through the reduction gear 18.

In the shut-off valve configured as described above, when the spring-winding motor 19 is operated to wind (spring-tighten) the spring spring 16 with the sector gear 13 in contact with the pin 14 of the circular plate 12, the sector gear 13 is shown in FIG. It rotates counterclockwise as indicated by the arrow 6 and is held away from the pin 14. At this time, the spring winding motor 19 maintains an energized state.
In this state, when the opening / closing motor 4 is operated and the sun gear 6 rotates counterclockwise as indicated by a broken line arrow in FIG. 6, each planetary gear 8 revolves counterclockwise while rotating clockwise. At this time, since the circular plate 12 connected to the planetary gear 8 and the connecting shaft 15 and the output shaft 2 are integrally rotated counterclockwise, the valve 1 is opened, and the opening / closing motor 4 is reversely rotated. By doing so, the valve 1 can be closed.
On the other hand, when the power supply is cut off in an emergency, the spring winding motor 19 is turned off, the mainspring 16 is released and rewinded, and the winding gear 17, the reduction gear 18, and the winding motor 19 rotate in the reverse direction to the winding, The sector gear 13 that meshes with the winding gear 17 rotates clockwise in the direction opposite to the arrow in FIG. 5 and pushes the pin 14 of the circular plate 12. Therefore, since the plate 12 with the pin 14 pressed rotates counterclockwise, each planetary gear 8 connected to the plate 12 revolves clockwise while rotating counterclockwise.
As a result, the sun gear 6 rotates and the output shaft 2 can rotate clockwise to close the valve 1.

JP 2010-38238 A

  However, the emergency shut-off valve has a complicated structure because the opening degree of the valve can be changed using a planetary mechanism. Therefore, as the mechanism becomes complicated, the probability of failure is high, and assembly work is difficult to prevent it. In addition, the number of parts to be assembled and managed increases, and there is a problem that the cost is high.

  Accordingly, an object of the present invention is to make it possible to change the opening degree with a simple structure without adopting a complicated structure such as a planetary mechanism.

  In order to solve the above problems, in the present invention, an output shaft connected to a valve and a reversible 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 An electromagnetic brake is provided, and comprises a shut-off valve body that operates the motor to open the valve and tightens a spring and then activates the electromagnetic brake, and a drive circuit. The drive circuit is provided with a motor current detection means. When the motor current detecting means detects the motor current, it opens (OFF) the connection between the electromagnetic brake and the power supply circuit that supplies the driving current to the brake. On the other hand, if the motor current is not detected, the electromagnetic brake And the power supply circuit are closed (ON), and when the power supply circuit is stopped due to an emergency power failure, the electromagnetic brake is released.

By adopting such a configuration, when the motor is energized to adjust the opening of the valve, the motor current detecting means detects the energized motor current and turns off the drive current from the power supply circuit to the electromagnetic brake. To. Therefore, the electromagnetic brake that has been holding the valve is in a released state, and the released valve can be wound around the spring by the operation of the motor, or the opening degree can be changed while the wound spring is extended. When the energization to the motor is stopped when the predetermined opening is reached, the motor current detecting means turns off the driving current from the power supply circuit to the electromagnetic brake because the motor current is not detected. Therefore, the electromagnetic brake supplied with the drive current can be operated to maintain a predetermined opening degree.
At this time, when the drive current from the power supply circuit to the electromagnetic brake disappears due to a power failure, the electromagnetic brake is released. Therefore, the valve is closed by the extension force of the spring wound according to the predetermined opening degree.

  At this time, the motor current detection means connects a series circuit in which a plurality of diodes are connected in series in the forward direction in parallel so that their polarities are opposite to each other, and is a parallel circuit inserted into the motor current supply path A switch unit configured to connect an input / output terminal of a light emitting element of a photocoupler to both ends of the parallel circuit and supply current to the electromagnetic brake through the light receiving element side input / output terminal; The structure which consists of can be employ | adopted.

With this configuration, the series circuit that forms the parallel circuit of the current detection unit generates a potential difference (the number of diodes connected in series × 0.6 V (saturation voltage)) when the motor current flows through the supply path. Therefore, using this potential difference as a power source, the light emitting element of the photocoupler of the switch unit connected to both ends of the parallel circuit is operated. Then, by turning off the light receiving element side input / output terminal by the operation of the light emitting element, the electromagnetic brake is released from the current supply from the power supply path, and the valve can be opened and closed by the motor. .
On the other hand, when the motor current is cut off (when the number of diodes is lower than the saturation voltage), the potential difference of the parallel circuit becomes zero, so the light emitting element of the photocoupler turns off and the input / output terminal on the light receiving element side is turned on. . By doing so, an electric current is supplied to the electromagnetic brake and the position of the valve can be maintained.
If a power failure occurs in this state, the electromagnetic brake is released because the current supply is cut off. Therefore, the valve is closed by the extension force of the spring wound according to the predetermined opening degree.

  Further, at this time, a fully closed sensor for detecting that the valve is closed and a fully opened sensor for detecting that the valve is opened are provided, and the fully closed sensor turns off the motor current supply path when the valve is closed, When the valve begins to open, the motor current supply path is turned on. On the other hand, the fully open sensor turns off the motor current supply path when the valve opens, and when the valve starts to close, the motor current supply path is turned on. can do.

By adopting such a configuration, when the motor is operated and the valve reaches the fully open position, the fully open sensor detects the state and turns off the motor current supply path. For this reason, the motor current detecting means detects that the motor current is turned off and the electromagnetic brake is actuated to hold the fully open position.
On the other hand, when the motor is operated and the valve reaches the fully closed position, the fully closed sensor detects this state and turns off the motor current supply path. For this reason, the motor current detecting means detects that the motor current is turned off, and the electromagnetic brake is operated to hold the fully closed position.

  Since the present invention is configured as described above, the opening degree of the emergency shutoff valve can be changed with a simple structure.

Perspective view of an embodiment Circuit diagram of the embodiment (A) Action illustration, (b) Action illustration, (c) Action illustration Circuit diagram of Example 1 Perspective view of conventional example 5 is an exploded perspective view of FIG.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
The electric emergency shut-off valve in this form includes a shut-off valve body and a drive circuit.

  As shown in FIG. 1, the shut-off valve body has an output shaft 20 to which a valve (not shown) is attached at the tip and an open / close motor (hereinafter referred to as a motor) 21 connected via a transmission mechanism 22 that combines a plurality of gears. The transmission mechanism 22 is attached with a biasing spring (for example, a spring) 23.

That is, the output shaft 20 has a configuration in which a spur gear is attached and a valve is attached to the tip. Also, two cams are attached to the rear end of the output shaft 20 with a phase difference of 90 degrees, and two micro switches, a fully open position setting micro switch LS1 and a fully closed position setting micro switch LS2, are attached to the cam. Thus, the opening / closing of the valve can be detected.
Here, normally closed contact setting (b contact) type switches are used for the fully open position setting micro switch LS1 and the fully closed position setting micro switch LS2, which are normally on and turned off when the valve is opened (or closed).

The motor 21 includes a motor shaft of an AC reversible motor with a gear head 26 mounted thereon and a braking electromagnetic clutch brake 27 mounted thereon. The gear head 26 having a pinion gear mounted by sliding the motor shaft with the clutch brake 27 is provided. It is possible to engage with the transmission mechanism 22 or lock the valve connected to the transmission mechanism 22 by fixing the motor shaft.
In this embodiment, an AC reversible motor is used as the motor 21, but the motor 21 is not limited to an AC reversible motor. As will be described later, a DC motor can be used by changing the current detection relay DTR.
The transmission mechanism 22 combines the transmission gears with different pitches to obtain the required torque, and attaches the spring 23 described above to the transmission gear that engages with the output shaft 20 to close the valve. It comes to be energized.

  In this shut-off valve, when the motor 21 is operated to open the valve, the spring of the transmission mechanism is also wound (tightened). Further, as will be described later, when the electromagnetic clutch brake 27 is released, the wound spring expands to close the valve.

  As shown in FIG. 2, the drive circuit includes a current detection relay DTR as a motor current detection means, an open direction control relay R1, a close direction control relay R2, a fully open position setting micro switch LS1, a fully close position setting micro switch LS2, and a rectification. The circuit 33 comprises a 4-wire input of an open command switch connection terminal T1, a close command switch connection terminal T2, and power supply connection terminals T3 and T4.

The open command switch connection terminal T1 is connected to the open input terminal 40 of the motor 21 via the open direction control relay contact r1. On the other hand, the closing command switch connection terminal T2 is connected to the closing input terminal 41 of the motor 21 via the closing direction control relay contact r2.
The common terminal 42 of the main coil and auxiliary coil of the motor 21 is connected to one of the power connection terminals T3 and T4 via a current detection relay DTR.

Here, the current detection relay DTR employs a mechanical relay having a normally closed contact output. When the current is detected (when the current flows through the coil), the contact is opened and the output is turned off. If is not detected (no current flows through the coil), the contact is closed and the output is turned on.
One power connection terminal T3 connected to the current detection relay DTR and the remaining terminal T4 are connected to the rectifier circuit 33.
Here, the rectifier circuit 33 is a full-wave rectifier circuit including a power transformer, a bridge rectifier, and a block capacitor. Three circuits are connected in parallel to the rectifier circuit 33.
That is, a first series circuit 45 in which a close direction control relay R2 and a fully closed position setting micro switch (normally closed “b” contact) LS2 are connected in series, an open direction control relay R1, and a fully open position setting micro switch (normally closed). “B” contact) The second series circuit 46 and the electromagnetic clutch brake circuit 27 connected in series with LS1 are connected in parallel, and a current detection relay is connected between the second series circuit 46 and the electromagnetic clutch brake circuit 27. The contact 47 is arranged.

  Further, as shown in FIG. 2, the operation switch 50 is connected to the open command switch connection terminal T1 and the close command switch connection terminal T2 of the four-wire input of the drive circuit. The operation switch 50 is a switching contact switch with an intermediate OFF (for example, an intermediate contact of a three-contact rotary switch can be freely connected), and the input / output terminal of the switch 50 is closed with the open command switch connection terminal T1. Connected to the command switch connection terminal T2, the common contact of the operation switch 50 is connected to the other terminal T4 of the AC power supply.

  In the electric emergency shut-off valve configured as described above, the valve is in the closed position before the power is turned on. Therefore, the normally closed contact fully open position setting microswitch LS1 is turned off when the contact is “closed”, and the normally closed contact fully closed position setting microswitch LS2 is turned on when the contact is “open”.

Now, when an AC power source is connected to the power connection terminals T3 and T4 and the power is turned on, the electric emergency shutoff valve operates as follows by the operation switch 50.
(1) Initial state immediately after power-on,
When the position of the operation switch 50 is neither the “open command switch connection” terminal T1 side nor the “close command switch connection” terminal T2 side, and is in the intermediate OFF position as shown in FIG.
In this case, since the valve immediately after turning on the power is in a closed state, as shown in FIG. 2, the fully open position setting micro switch LS1 is OFF at the contact “closed”, and the open direction control relay R1 is ON and the open direction The control relay contact r1 is held in the on (“closed”) state.
On the other hand, the fully closed position setting micro switch LS2 is ON when the contact is “open”, the close direction control relay R2 is OFF, and the close direction control relay contact r2 is also OFF (“open”).
At this time, since the operation switch 50 is in an intermediate OFF position, the power from the AC power source is not supplied to any of the terminals T1 and T2 of the “open command switch connection” terminal T1 or the “close command switch connection” terminal T2. No current flows. Accordingly, since the current detection relay DTR is turned off and the current detection relay contact 47 is turned on (“closed”), the electromagnetic clutch brake 27 is operated and the valve is held in the fully closed state.

(2) When the valve is fully opened from fully closed (the position of the operation switch 50 is operated to the “open command switch connection” terminal T1 side).
In this case, as shown in FIG. 2, the position of each contact in the fully closed state is that the fully open position setting micro switch LS1 is OFF when the contact is “closed”, and the open direction control relay R1 is ON and the open direction control is performed. The relay contact r1 is held in an on (“closed”) state. Further, the fully closed position setting micro switch LS2 is turned on at the contact “open”, the close direction control relay R2 is turned off, and the close direction control relay contact r2 is turned off (“open”).
Therefore, electric power is supplied from the AC power source to the open input terminal 40 of the motor 21 via the open direction control relay contact r1, the motor current flows, and the current detection relay DTR is turned on.
As a result, the current detection relay contact 47 is turned off (“open”), and power supply to the electromagnetic clutch brake 27 is cut off. Therefore, the valve released from the locking of the brake 27 is rotated by winding the spring 23 in the valve opening direction by the operation of the motor 21.
At this time, when the motor 21 starts to rotate, the normally closed contact fully closed position setting micro switch LS2 is turned off at the contact “closed”, the closing direction control relay R2 is turned on, and the closing direction control relay contact r2 is turned on. Holds the on (“closed”) state.
When the rotating valve reaches the fully open position, as shown in FIG. 3 (a), the fully open position setting micro switch LS1 which is a normally closed contact is turned off with the contact "open", and the open direction control relay R1. Is turned off, and the open direction control relay contact r1 is turned off ("open"). Therefore, the power supply to the motor 21 is cut off, the motor current stops flowing, and the current detection relay DTR is turned off.
As a result, the current detection relay contact 47 is turned on (“closed”) and power supply to the electromagnetic clutch brake 27 is started, so that the electromagnetic clutch brake 27 is operated and the valve is held in a fully opened state.

(3) When closing the valve from fully open,
The position of the operation switch 50 is operated toward the “close command switch connection” terminal T2.
In this case, as shown in FIG. 3 (a), the position of each contact when the valve is fully open is the normally open contact fully open position setting microswitch LS1 is ON when the contact is "open", and the opening direction control relay R1 Is off and the open direction control relay contact r1 is off ("open"). In addition, the normally closed contact fully closed position setting micro switch LS2 is OFF when the contact is “closed”, the close direction control relay R2 is ON, and the close direction control relay contact r2 is ON (“closed”). .
Therefore, when the operation switch 50 is operated to the “close command switch connection” terminal T2 side, power is supplied from the AC power source to the close input terminal 41 of the motor 21 via the close direction control relay contact r2, and the motor current flows to The detection relay DTR is turned on.
As a result, the current detection relay contact 47 is turned off (“open”), and the power supply to the electromagnetic clutch brake 27 is cut off. Therefore, the valve released from the holding of the brake 27 is closed by the operation of the motor 21. The spring 23 rotates while extending in the valve direction.
When the rotating valve reaches the fully closed position, as shown in FIG. 3 (b), the fully open position setting micro switch LS1 which is a normally closed contact is turned off with the contact "closed", and the open direction control relay R1 is turned on and the open direction control relay contact r1 is turned on (“closed”). In addition, the normally closed contact fully closed position setting micro switch LS2 is turned on with the contact "open", the close direction control relay R2 is turned off, and the close direction control relay contact r2 is turned off ("open"). Become.
Accordingly, the power supply to the motor 21 is interrupted and the motor current does not flow, so the current detection relay DTR is turned off.
As a result, the current detection relay contact 47 is turned on (“closed”), power is supplied to the electromagnetic clutch brake 27, the electromagnetic clutch brake 27 is activated, and the valve is held in a fully closed state.

(4) When holding the valve at the required opening (intermediate position)
The position of the operation switch 50 is operated to either the “open command switch connection” terminal T1 side or the “close command switch connection” terminal T2 side, and when the required opening is reached, the operation switch 50 is operated to the intermediate OFF position.
For example, consider a case where the position of the operation switch 50 is operated to the “open command switch connection” terminal T1 side from the fully closed state and the intermediate switch is operated when the required opening is reached.
In this case, as shown in FIG. 3B, the position of each contact in the fully closed state is that the normally closed contact fully open position setting microswitch LS1 is OFF when the contact is “closed”, and the open direction control relay R1 is The opening direction control relay contact r1 is turned on (closed). In addition, the normally closed contact fully closed position setting micro switch LS2 is turned on when the contact is "open", the close direction control relay R2 is turned off, and the close direction control relay contact r2 is turned off ("open"). ing.
Therefore, when the position of the operation switch 50 is operated to the “open command switch connection” terminal T1 side, power is supplied from the AC power source to the open input terminal 40 of the motor 21 via the open direction control relay contact r1, and the motor current flows. The current detection relay DTR is turned on.
As a result, the current detection relay contact 47 is turned off ("open"), and the power supply to the electromagnetic clutch brake 27 is cut off. Therefore, the valve released from the locking of the brake 27 is caused by the operation of the motor 21. It rotates while winding the spring 23 in the valve opening direction.
At this time, when the motor 21 starts to rotate, the normally closed contact fully-closed position setting microswitch LS2 is turned off with the contact "open", so the closing direction control relay R2 is turned on and the closing direction control is performed. The relay contact r2 is turned on (“closed”).
In this state, when the position of the operation switch 50 reaches the required opening, the intermediate switch is operated to the intermediate OFF position. Then, as shown in FIG. 3C, the power supply to the motor 21 is stopped, so that the motor current stops flowing and the current detection relay DTR is turned off.
As a result, the current detection relay contact 47 is turned on ("opened"), and power supply to the electromagnetic clutch brake 27 is started, so that the valve is held at a required opening by the operated electromagnetic clutch brake 27.
Further, when changing the opening degree, as shown in FIG. 3C, the contact r1 of the opening direction control relay R1 and the contact r2 of the closing direction control relay R2 are turned on (“closed”). If the position of 50 is operated on either the “open command switch connection” terminal T1 side or the “close command switch connection” terminal T2 side, a current can be supplied to the motor 21. When the motor current flows in this way, the current detection relay DTR is turned on, the current detection relay contact 47 is turned off (“open”), and the power supply to the electromagnetic clutch brake 27 is cut off. The opening of the valve released from the engagement can be changed while the spring 23 is wound or extended by the operation of the motor 21.
Then, when the opening of the valve reaches the required position, when the position of the operation switch 50 is operated to the intermediate OFF position, the power supply to the motor 21 is stopped, the motor current stops flowing, and the current detection relay DTR is turned on. Turn off.
As a result, the current detection relay contact 47 is turned on (“closed”) and power supply to the electromagnetic clutch brake 27 is started, so that the valve is held at a required opening by the operated electromagnetic clutch brake 27.
Further, when the valve is to be fully opened or fully closed from this state, the position of the operation switch 50 is operated to either the “open command switch connection” terminal T1 side or the “close command switch connection” terminal T2 side. That's fine. By operating in this way, the motor current flows, the current detection relay DTR is turned on, the current detection relay contact 47 is turned off (“open”), and the power supply to the electromagnetic clutch brake 27 can be cut off. Therefore, the valve can be fully opened or fully closed while the spring 23 is wound or extended by the operation of the motor 21.
At that time, in the case of full opening, when the valve is fully opened, the normally closed contact full open position setting micro switch LS1 is turned on with the contact "open" and the open direction control relay R1 is turned off. The direction control relay contact r1 is held in the off (“open”) state. In the case of the fully closed state, when the valve is fully closed, the normally closed contact fully closed position setting micro switch LS2 is turned on with the contact "open", and the closing direction control relay R2 is turned off. The contact r2 of the closing direction control relay R2 is maintained in the on (“open”) state.
In this way, the opening of the valve can be freely changed.

(5) Power failure When the valve is held fully open, or when the valve is held at the required opening (intermediate position), a power failure occurs due to an emergency situation, and the electromagnetic clutch When the drive current to the brake 27 disappears, the electromagnetic clutch brake 27 is released, and the valve is closed by the extension force of the spring 23 tightened according to a predetermined opening degree.
At this time, the closed valve needs to be pressed with spring pressure to resist the fluid, and the amount of tightening of the spring 23 is set so that such spring pressure can be generated when the valve is closed. Of course you need to do.

As described above, the valve opening / closing mechanism has a simplified structure in which the transmission mechanism 22 that connects the output shaft 20 and the motor 21 is simply provided with the spring 23. By doing so, the electromagnetic clutch brake 27 is released (free) in the event of a power failure, so that the valve can be urgently shut off by the extension force of the spring 23.
As a result, it is possible to reduce the number of parts and assembly man-hours of the emergency shut-off valve, and the cost can be reduced.
Further, the number of parts to be assembled and managed in the mechanism portion is reduced, and the probability of failure can be reduced.
Further, it is not necessary to wind up and set the spring 23 after installation or inspection, and an immediate opening / closing operation is possible. Therefore, there is no need for a switch for detecting completion of spring winding.

The first embodiment shows an example of the current detection relay DTR.
The current detection relay DTR according to the first embodiment includes a current detection unit 60 and a switch unit 61, as shown in FIG.
The current detector 60 is a series circuit 62 in which a plurality of diodes D are connected in series in the forward direction and connected in parallel so that their polarities are opposite to each other. The parallel circuit 63 is inserted into the motor current path. .
Thus, the parallel circuit 63 generates a potential difference (the number of diodes connected in series × 0.6 V (saturation voltage)) when the motor current flows in the motor current path. At this time, since the series circuit in which the diodes D are connected in series as described above is a parallel circuit in which the polarities are connected to each other, the motor current flowing in the supply path is AC, DC, and motor inversion. Can be detected regardless.
On the other hand, the switch unit 61 uses a photocoupler 64, connects the input / output terminals of the light emitting element 65 of the photocoupler 64 to both ends of the parallel circuit 63, and electromagnetic clutch brakes via the input / output terminals of the light receiving element. 27 is to supply current.
Here, in the case of FIG. 4, two diodes are used for the light emitting element 65, and the two diodes are connected in parallel so that their polarities are opposite to each other. It can be detected regardless of.
Therefore, as the motor 21, it is possible to use not only an AC motor but also a DC motor in which the direction of the motor current changes forward and reverse.
As shown by the broken line in FIG. 4, it is natural that the output of the light receiving element is an inverted output in accordance with the specifications of the electromagnetic clutch brake 27 and the configuration of the drive circuit.

In the current detection relay DTR configured in this manner, when the parallel circuit 63 of the current detection unit 60 inserted in the motor current path flows into the current path, the potential difference (the number of diodes connected in series × 0.6 V ( Saturation voltage)). For this reason, the light emitting element 65 of the switch unit 61 (photocoupler 64) connected to both ends of the parallel circuit 63 emits light by this potential difference, and the input / output terminals on the light receiving element side are turned on.
And, for example, as shown by the broken line in FIG. 4, by turning off the transistor switch circuit inserted in the motor current path, the current supply to the electromagnetic clutch brake 27 is cut off and the released state is established. It can be opened and closed.
On the other hand, when the motor current is interrupted (when the number of diodes is lower than the saturation voltage), the potential difference of the parallel circuit 63 becomes zero, so that the light emitting element 65 of the switch unit 61 is turned off and the light receiving element is turned off. Therefore, by enabling the current to be supplied to the electromagnetic clutch brake 27 with the light receiving element off, the electromagnetic clutch brake 27 can be operated to hold the valve position.
In addition, when a power failure occurs in this held state, the electromagnetic clutch brake 27 enters a released state in which the current supply is cut off. Therefore, the valve can be closed by the extension force of the spring tightened according to the predetermined opening degree.

  Thus, since the current detection relay DTR can be formed of a semiconductor, reliability can be improved. In addition, by appropriately setting the number of diodes in the current detection unit, it is possible to improve resistance to noise and the like.

20 output shaft 21 motor 22 transmission mechanism 23 spring 27 electromagnetic clutch brake 45 first series circuit 46 second series circuit 60 current detection unit 61 switch unit 62 series circuit 63 parallel circuit 64 photocoupler 65 light emitting element D diode DTR current detection Relay LS1 Fully open position setting micro switch LS2 Fully closed position setting micro switch

Claims (3)

The output shaft (20) connected to the valve and the reversible motor (21) are connected via a transmission mechanism (22) combining a plurality of gears, and a spring (23) for urging the valve in the closing direction and braking of the valve An electromagnetic brake (27) for operating the electromagnetic brake (27) after operating the motor (21) to open the valve and tightening the spring (23) and driving the electromagnetic brake (27 ); A circuit,
The drive circuit is provided with motor current detection means (DTR), and when the motor current detection means (DTR) detects the motor current, a power supply circuit that supplies the electromagnetic brake (27) and the brake (27) with drive current When the connection with (33) is opened (OFF) and no motor current is detected, the connection between the electromagnetic brake (27) and the power supply circuit (33) is closed (ON) and the power supply circuit (33) The electric emergency shut-off valve is characterized in that the electromagnetic brake (27) is released when is stopped due to a power failure in an emergency. The motor current detection means (DTR) connects a series circuit (62) in which a plurality of diodes (D) are connected in series in the forward direction in parallel so that their polarities are opposite to each other, and a motor current supply path The current detection unit (60) composed of a parallel circuit (63) inserted in the input and output terminals of the light emitting element (65) of the photocoupler (64) are connected to both ends of the parallel circuit (63) to receive light. The electric emergency shut-off valve according to claim 1, comprising a switch portion (61) configured to supply current to the electromagnetic brake (27) via the element side input / output terminal. A fully closed sensor (LS2) for detecting that the valve is closed and a fully open sensor (LS1) for detecting that the valve is open are provided, and the fully closed sensor (LS2) is a motor current supply path when the valve is closed. When the valve begins to open, the motor current supply path is turned on. On the other hand, the fully open sensor (LS1) turns off the motor current supply path when the valve is opened, and when the valve begins to close, the motor current supply path. The electric emergency shut-off valve according to claim 1 or 2, characterized in that is turned on.

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