JPH08293219A - Operating apparatus for switch - Google Patents

Abstract

PURPOSE: To provide an operating apparatus for a switch in which the adjustment of the position of the limit switch commanding the stop of a motor can be facilitated. CONSTITUTION: A roller 12 is fitted to a screw bar 1 rotating driven by a motor 7 and to a moving element 5 having a female screw which engages with the screw portion of the screw bar 1. The roller 12 is fitted in the slit 14a of an arm 14 fitted to a main shaft 13 so as to rotate the main shaft with the displacement of the moving element 5. The rotation of the main shaft 13 is coupled to the operating shaft of a switch so as to operate the switch. Limit switches LS11 , LS21 which detect the completion of the open circuit operation and the close circuit operation of the switch and the limit switches LS12 , LS22 which command the stop of a motor after the completion of the operation of the switch are arranged side by side in the shaft line direction of the screw bar 1 so that the limit switches LS11 , LS21 , LS12 , LS22 are directly actuated by the moving element 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch operating device used to operate a switch such as a disconnect switch or a ground switch.

[0002]

2. Description of the Related Art As a switch operating device using an electric motor as a drive source, one using a feed screw mechanism is known. FIG.
Shows a conventional switch operating mechanism using a feed screw mechanism. In the figure, 1 is a screw rod supported by a frame 2 of the operating device through bearings 3 and 4, and 5 is a screw of the screw rod 1. It is a mover that has a female screw threaded to the portion 1a and is linearly displaced as the screw rod 1 rotates. A spur gear 6 is attached to one end of the screw rod 1. The electric motor 7 is fixed to a portion (not shown) of the frame 2 in a state where the axis of the output shaft 7a is parallel to the axis of the screw rod 1.
A pinion gear 9 coupled to the output shaft 7 a of the above through a coupling 8 is screwed to the spur gear 6. Screw rod 1
The mover 5, the electric motor 7, the spur gear 6 and the pinion gear 9
The screw feed mechanism 10 is configured by the speed reducing mechanism consisting of, and the mover 5 is linearly displaced in the axial direction of the screw rod 1 by the rotation of the electric motor 7. A shaft 11 protruding in a direction perpendicular to the axis of the screw rod 1 is fixed to the mover 5, and a roller 12 is rotatably attached to the shaft 11.

Reference numeral 13 denotes a main shaft (output shaft) of an operating device which is rotatably supported by a portion (not shown) of the frame 2. The main shaft has its axis orthogonal to the axis of the screw rod 1 and the mover 5
It is provided in a state of being parallel to the axis of the shaft 11 provided in the. The main shaft 13 is provided so that one end thereof is located laterally of the central portion in the longitudinal direction of the screw rod 1.
A prismatic portion 13a is formed on one end side of 3, and the prismatic portion is fitted into a square hole provided in the plate-like arm 14. A screw portion 13b is provided at one end of the main shaft 13, and the arm 14 is fixed to the main shaft 13 by a nut (not shown) screwed to the screw portion 13b. The arm 14 is provided with a C-shaped notch groove 14a opening to the side of the mover 5, and the roller 1 is provided in the notch groove 14a.
2 is fitted. Therefore, when the mover 5 is linearly displaced in the axial direction of the screw rod 1, the arm 14 rotates, and the rotation of the arm 14 is transmitted to the main shaft 13. Since the cutout groove 14a of the arm 14 into which the roller 12 is fitted is formed in a V shape, the rotation amount of the arm 14 with respect to the displacement amount of the roller 12 is measured by the roller 12 from the central portion of the cutout groove 14a. It becomes smaller as it moves toward the opening end. In this example, the roller 12 and the arm 14 constitute a conversion mechanism that converts the linear motion of the mover into a rotary motion and transmits the rotary motion to the main shaft 13.

The other end of the main shaft 13 is projected to the outside from the frame 2 of the operating device, and the other end of the main shaft 13 is rotated by the operating shaft of a switch (not shown) when the switch is opened and closed. The shaft to be connected) is directly coupled via a coupling or an appropriate coupling mechanism (link mechanism or the like).
When operating the switch with this operator, the mover 5
Is linearly displaced in one direction and the main shaft 13 is rotated in one direction, the closing operation of a switch (not shown) is performed, and when the mover 5 is linearly displaced in the other direction and the main shaft 13 is rotated in the other direction. The opening operation of the switch is performed. The relationship between the displacement direction of the mover and the opening / closing operation of the switch is arbitrary, but in this example, the closing operation of the switch is performed when the main shaft 13 is rotated clockwise by the displacement in the left direction in the drawing. It is assumed that the switch opening operation is performed when the mover 5 is displaced rightward in the drawing and the main shaft 13 rotates counterclockwise.

In this type of operating device, it is necessary to stop the electric motor 7 promptly when the opening or closing operation of the switch is completed. For that purpose, the opening and closing operations of the switch are completed respectively. It is necessary to generate a command signal for instructing to stop the electric motor 7 by detecting that. Therefore, in the conventional operating device, the arm 14
A dog plate 15 is fixed to the tip of the dog plate 15, and one end of the dog plate 15 in the rotating direction is opened by the dog plate 15 when the opening operation of the switch is completed. A limit switch LS11 and a limit switch LS12 for stopping the motor during open circuit operation, which generates a command signal for driving the dog plate 15 to stop the electric motor after the limit switch LS11 performs a detection operation, are arranged. On the other side of the rotating direction of the plate 15, the limit switch LS21 for detecting the closing operation, which is driven by the dog plate 15 to perform the detecting operation when the closing operation of the switch is completed, and the limit switch LS21 detect the detecting operation. The limit switch L for stopping the electric motor at the time of closing operation, which generates a command signal for instructing to stop the electric motor after being driven by the dog plate 15. S22 and was arranged. Each limit switch has a plunger P, and when the plunger is pushed by the toggle plate 15, a detection operation or a command signal is generated (ON operation or OFF operation). 5A and 5B are respectively the Z of FIG.
A view of the limit switch from the 1 and Z2 directions.
The limit switches LS11, LS12 and LS21, LS22 are arranged so as to be slightly displaced so that they are driven by the toggle plate with a slight delay. The chain line p shown in FIG. 5 indicates the position of the plunger of each limit switch.

A signal obtained by each of the limit switches is given to a control circuit for controlling the electric motor 7, a predetermined limit switch detects the completion of the opening operation or the closing operation, and a command for instructing to stop the electric motor. When a signal is generated, the electric power to the electric motor 7 is cut off to stop the electric motor.

[0007]

In the conventional switch operating device shown in FIG. 4, the movable contact of the switch is completely separated from the fixed contact (when the opening operation is completed) or the movable contact. When the child completely contacts the fixed contact (when the closing operation is completed), the operation completion detection limit switch LS11 or LS21 operates, and after these limit switches operate, the motor stop limit switch LS
12 or LS22 is configured to operate. Therefore, even after the operation of the switch is completed, the limit switch LS
The electric motor 7 continues to rotate until 12 or LS22 operates, and the movable contactor of the switch overstrokes. In order to reduce the overstroke amount of the movable contact as much as possible, the shape of the notch groove 14a provided in the arm 14 is formed into a V shape so that the rotation amount of the main shaft 13 relative to the displacement amount of the movable element 5 after the opening / closing operation is completed. I am less. Therefore, after the opening operation is completed and after the closing operation is completed, the rotation amount of the main shaft 13 with respect to the displacement amount of the mover 5 is very small, and the motor stop limit switch L
S12 and LS22 are limit switches L for operation completion detection
After S11 and LS21 are operated, it is necessary to operate them in a region where the rotation amount of the main shaft 13 with respect to the displacement amount of the mover 5 is small. Therefore, in the conventional operation device of this type, the adjustment range of the position of the limit switch for stopping the electric motor becomes extremely small, and there is a problem that the adjustment work takes time.

Further, in the operating device shown in FIG. 4, the dog plate 15 is used.
Since it is necessary to secure a special space necessary for rotating the actuator, and also to secure a space for arranging the limit switches on both sides of the dog plate 15, it is possible to avoid making the actuator large. I couldn't do it.

It is an object of the present invention to provide an operating device for a switch which can easily adjust the position of a limit switch for stopping an electric motor and can be made more compact than before.

[0010]

SUMMARY OF THE INVENTION The present invention is directed to a main shaft that is directly or via a connecting mechanism connected to an operating shaft of a switch, a screw rod that is driven to rotate by an electric motor, and a female screwed to the screw rod. A feed screw mechanism including a mover having a screw and linearly displaced with the rotation of a screw rod, and a conversion mechanism converting the linear motion of the mover into a rotary motion and transmitting the rotary motion to the main shaft. It also relates to a switch operating device.

In the present invention, when the mover reaches the position for completing the operation of the switch, the operation completion detection limit switch driven by the mover to perform the detection operation, and the mover for the operation completion detection. Immediately after the limit switch is driven, a motor stop limit switch that is driven by the mover to generate a command signal for instructing to stop the motor is arranged side by side in a direction parallel to the axis of the screw rod.

According to a preferred aspect of the present invention, when the mover reaches a position for completing the opening operation of the switch, the open switch operation completion detecting limit switch driven by the mover to perform a detecting operation, and the mover are provided. Immediately after driving the limit switch for detecting the completion of the open circuit, a command signal for instructing to stop the electric motor is generated by being driven by the mover, and the limit switch for stopping the motor during open circuit operation, and the mover closes the switch. And a limit switch for detecting a closing operation which is driven by the mover to perform a detection operation when the position reaches a position for completing the closing operation, and a mover immediately after driving the limit switch for detecting the closing operation completion. Provided with a limit switch for stopping the electric motor during closing operation that generates a command signal for instructing to stop the electric motor,
These limit switches are arranged side by side in a direction parallel to the axis of the screw rod.

[0013]

As described above, the operation completion detecting limit switch for detecting the completion of the operation of the switch, and the motor stop limit switch for instructing to stop the electric motor after the completion of the operation of the switch are detected. Are arranged side by side in the axial direction of the screw rod and driven by the mover,
Since the displacement of the mover is relatively large even after the operation of the switch is completed, the allowable range of the installation position of the motor stop limit switch can be widened and the position of the limit switch can be easily adjusted. You can

Further, as described above, when a plurality of limit switches are arranged side by side along the axis of the screw rod, the limit switches can be arranged by effectively utilizing the dead space formed on the side of the feed screw mechanism. The space required to place the limit switch can be reduced compared to a conventional actuator that has a dog plate attached to the arm that transmits the displacement of the mover to the main shaft, and the actuator can be made compact. be able to.

[0015]

1 to 3 are front views partially showing the structure of the essential part of an embodiment of the present invention, and FIG. 1 shows a state in which a mover of a feed screw mechanism is at a neutral position. 2 shows the state when the mover of the feed screw mechanism reaches the completion position of the circuit opening operation. Further, FIG. 3 shows a state in which the mover of the feed screw mechanism reaches the stop position of the electric motor after completion of the opening operation.

1 to 3, parts that are the same as the parts of the conventional operating device shown in FIG. 4 are given the same reference numerals. In these figures, 1 is a screw rod supported by a frame 2 of an operating device via bearings 3 and 4, and 5 is a mover having a female screw screwed into a screw portion 1a of the screw rod 1, The rotation of the output shaft 7a of the electric motor 7 is transmitted to the motor 1 via a reduction mechanism including a pinion gear 9 and a spur gear 6. The screw rod 1, the mover 5, the electric motor 7, and the speed reducing mechanism including the spur gear 6 and the pinion gear 9 constitute a screw feed mechanism 10. The rotation of the electric motor 7 causes the mover 5 to move in the axial direction of the screw rod 1. Linearly displaced. The mover 5 has a shaft 1 protruding in a direction perpendicular to the axis of the screw rod 1.
1 is fixed, and a roller 12 is rotatably attached to the shaft 11.

The axis 13 is orthogonal to the axis of the screw rod 1,
A main shaft provided in a state parallel to the axis of a shaft 11 provided on the mover 5, and a prismatic portion 13a provided on one end side of the main shaft 13 having a prismatic hole provided on a plate-like arm 14. 13b fitted to one end of the main shaft 13
The arm 14 is fixed to the main shaft 13 by a nut (not shown) screwed into the. The roller 1 attached to the mover 5 in the V-shaped cutout groove 14 a provided in the arm 14.
2, the linear motion of the mover 5 is converted into a rotary motion by the arm 14 and transmitted to the main shaft 13. The roller 12 and the arm 14 constitute a conversion mechanism that converts the linear motion of the mover 5 into a rotary motion and transmits the rotary motion to the main shaft 13.

Since the cutout groove 14a of the arm 14 into which the roller 12 is fitted is formed in a V shape, the rotation amount of the arm 14 with respect to the displacement amount of the roller 12 is the same as that of the cutout groove 14a of the roller 12. It becomes smaller as it moves from the center to the opening end side.

The other end of the main shaft 13 is projected to the outside from the frame 2 of the operating device, and the other end of the main shaft 13 is rotated by the operating shaft of a switch (not shown) when opening and closing the switch. The shaft to be connected) is directly coupled via a coupling or an appropriate coupling mechanism (link mechanism or the like).

Also in this embodiment, when the mover 5 is displaced leftward in the drawing and the main shaft 13 is rotated clockwise, the switch is closed, and the mover 5 is displaced rightward in the drawing. Then, the opening operation of the switch is performed when the main shaft 13 rotates counterclockwise.

The construction of each of the above parts is similar to that of the conventional operating device shown in FIG. 4, but in the present embodiment, a limit switch LS11 for detecting the completion of the opening operation and a limit switch LS12 for stopping the motor during opening operation are provided. The closing switch LS21 for closing the closing operation and the limit switch LS22 for stopping the motor during closing operation are arranged side by side on a straight line parallel to the axis of the screw rod 1 so that the limit switch LS22 for closing the closing motor can be directly driven by the mover 5 to operate. There is.

In the example shown in the figure, the support bases 20, 20 are arranged at intervals in the axial direction of the screw rod 1 and are fixed to a portion (not shown) of the frame 2 of the operating device, in the axial direction of the screw rod 1. A strip-shaped mounting plate 21 extending parallel to the screw rod is fixed, and each limit switch is mounted on the mounting plate 21. Each limit switch is supported by a mounting plate 21 via a slide mechanism so that it can move in the axial direction of the threaded rod 1 by a predetermined distance. Each limit switch can be fixed by an appropriate locking means. Also, each limit switch is a plunger P
And is configured to perform an on operation or an off operation when the plunger is pushed, and when the mover 5 moves to a predetermined position, the side surface of the mover has a predetermined limit switch. The position of each limit switch with respect to the moving direction of the mover 5 and the distance between each limit switch and the screw rod 1 are set so that the plunger is pressed to operate the limit switch.

To describe in more detail, the limit switch LS11 for detecting the completion of the opening operation is such that when the mover 5 reaches the position for completing the opening operation of the switch, its plunger is pushed by the side surface of the mover 5. The limit switch LS12 for stopping the motor during the opening operation is positioned by the moving element 5 with a predetermined (slight) delay after the moving element 5 drives the limit switch LS11 for detecting the completion of the opening operation. Is pressed to generate a command signal (ON operation or OFF operation). Further, the closing operation completion detection limit switch LS21 is positioned so that the plunger is pushed by the side surface of the moving element 5 to perform the detection operation when the mover 5 reaches the position for completing the closing operation of the switch. ,
The limit switch LS22 for stopping the motor during closing operation causes the mover 5 to push its plunger with a predetermined (slight) delay after driving the limit switch LS21 for detecting completion of closing operation, thereby causing the command signal to be generated. Positioned to do.

In this embodiment, for example, when closing the switch, the electric motor 7 is rotated in one direction to move the mover 5 to the right in the drawing, and the main shaft 13 is rotated counterclockwise. When the mover 5 reaches the position for completing the closing operation of the switch, the mover 5 contacts the plunger P of the closing operation completion detection limit switch LS21 to push the plunger P, as shown in FIG. Operate the limit switch LS21. After that, the mover 5 is further displaced to the right while maintaining the state of being in contact with the plunger P of the limit switch LS21 (the state of pushing the plunger),
As shown in (4), the limit switch LS22 for stopping the motor at the time of closing operation is brought into contact with the plunger P, and the plunger P is pushed to operate the limit switch LS22. When the limit switch LS22 operates, the control circuit of the electric motor 7 stops energizing the electric motor 7 and stops the electric motor 7. The operation when opening the switch is also the same.

When operating the switch using the operating device of the above-mentioned embodiment, it is necessary to minimize the overstroke amount of the movable contactor of the switch after the operation of the switch is completed. In the above-mentioned operating device, the notch groove 14a provided in the arm 14 is set in a V shape so that when the movable contact of the switch enters the overstroke region,
Since the ratio of the rotational displacement amount of the main shaft to the displacement amount of the mover is set to be small, the variable amount of the mover 5 allowed in the overstroke region is relatively large. Therefore, as in the above embodiment, the operation completion detection limit switches LS11 and LS21 for detecting the completion of the operation of the switch, and the electric motor for instructing to stop the electric motor after the completion of the operation of the switch is detected. Stop limit switch LS12, L
When S22 and S22 are arranged side by side in the axial direction of the screw rod 1 and these limit switches are driven by the mover 5, the limit switches LS12 and LS for stopping the motor are arranged.
The allowable range of the installation positions of 22 can be widened, and the positions of these limit switches can be easily adjusted.

Further, as described above, when a plurality of limit switches are arranged side by side along the axis of the screw rod 1, the limit switches can be arranged by effectively utilizing the dead space formed on the side of the feed screw mechanism 10. Therefore, compared with the conventional operating device in which the dog plate for driving the limit switch is attached to the arm 14 that transmits the displacement of the mover to the main shaft,
The space required for disposing the limit switch can be reduced, and the operating device can be made compact.

Further, if the limit switch is directly driven on the side surface of the mover 5 as in the above embodiment,
Since it is not necessary to specially provide a dog for driving the limit switch, the number of parts can be reduced.

The preferred embodiments of the present invention have been described above. The main aspects of the invention disclosed in this specification are as follows.

(1) A threaded rod having a main shaft directly connected to an operating shaft of a switch or via a connecting mechanism, a screw rod rotated by an electric motor, and a female screw screwed to the screw rod. In a switch operating device including a feed screw mechanism including a mover that is linearly displaced with the rotation of, and a conversion mechanism that converts the linear motion of the mover into a rotary motion and transmits the rotary motion to the spindle. An operation completion detection limit switch that is driven by the mover to perform a detection operation when the mover reaches a position to complete the operation of the switch, and the mover drives the operation completion detection limit switch. Immediately after that, a limit switch for stopping the electric motor that generates a command signal for instructing to stop the electric motor driven by the mover is arranged side by side in a direction parallel to the axis of the screw rod. Characteristic switch operating device.

(2) A screw rod having a main shaft directly connected to the operating shaft of the switch or through a connecting mechanism, a screw rod driven by an electric motor, and a female screw screwed to the screw rod. A feed screw mechanism including a mover that is linearly displaced in accordance with the rotation, and a conversion mechanism that converts a linear motion of the mover into a rotary motion and transmits the rotary motion to the main shaft. It has an arm attached to the main shaft and having a squared V-shaped cutout opening on the mover side, and a roller attached to the mover and fitted in the cutout groove of the arm. Then, in the process in which the mover is displaced from the central portion of the screw rod to one end side and the other end side of the screw rod, as the displacement amount of the mover increases, the rotational displacement of the main shaft with respect to the displacement amount of the mover increases. Configured so that the proportion of volume decreases In the switch operating device
An operation completion detection limit switch that is driven by the mover to perform a detection operation when the mover reaches a position to complete the operation of the switch, and the mover drives the operation completion detection limit switch. Immediately after that, a limit switch for stopping the electric motor which generates a command signal for instructing to stop the electric motor driven by the mover,
A switch operating device, which is arranged side by side in a direction parallel to the axis of the screw rod.

(3) A screw rod having a main shaft connected directly to the operating shaft of the switch or via a connecting mechanism, a screw rod rotated by an electric motor, and a female screw screwed to the screw rod. A feed screw mechanism including a mover that is linearly displaced in accordance with the rotation, and a conversion mechanism that converts a linear motion of the mover into a rotary motion and transmits the rotary motion to the main shaft. It has an arm attached to the main shaft and having a squared V-shaped cutout opening on the mover side, and a roller attached to the mover and fitted in the cutout groove of the arm. Then, in the process in which the mover is displaced from the central portion of the screw rod to one end side and the other end side of the screw rod, as the displacement amount of the mover increases, the rotational displacement of the main shaft with respect to the displacement amount of the mover increases. Configured so that the proportion of volume decreases In the switch operating device
A limit switch for detecting the opening operation completion, which is driven by the mover to perform a detection operation when the mover reaches a position where the opening operation of the switch is completed, and a limit switch for detecting the opening operation completion of the mover. And a position at which the mover completes the closing operation of the switch when the motor is stopped by the mover to generate a command signal to stop the electric motor immediately after driving the motor. Limit switch for detecting a closing operation completion which is driven by the mover to perform a detecting operation when the moving speed is reached, and the electric motor driven by the mover immediately after the limiter for closing the closing operation is driven by the mover. A limit switch for stopping the motor during closing operation that generates a command signal to stop the motor is connected in parallel with the axis of the screw rod. Switch operating device, characterized in that arranged side by side in the direction.

[0032]

As described above, according to the present invention, the operation completion detecting limit switch for detecting the completion of the operation of the switch and the stop of the electric motor after the completion of the operation of the switch are detected. Since the motor stop limit switch for commanding is arranged side by side in the axial direction of the screw rod and driven by the mover, the allowable range of the installation position of the motor stop limit switch can be widened and the limit switch There is an advantage that the position can be easily adjusted.

Further, according to the present invention, since the plurality of limit switches are arranged side by side along the axis of the screw rod, the limit switches are arranged by effectively utilizing the dead space formed on the side of the feed screw mechanism. Compared to a conventional actuator that has a dog plate for driving the limit switch mounted on the arm that transmits the displacement of the mover to the main shaft, the space required for arranging the limit switch can be reduced to operate. The container can be made compact.

[Brief description of drawings]

FIG. 1 is a front view showing a partial cross-section of the structure of a main part of an embodiment of the present invention, showing a state in which a mover of a feed screw mechanism is in a neutral position.

FIG. 2 is a front view showing a partial cross-section of the structure of the essential parts of an embodiment of the present invention, showing the state when the mover of the feed screw mechanism reaches the position where the opening operation of the switch is completed. It is a figure.

FIG. 3 is a front view showing a partial cross-section of the configuration of the essential parts of an embodiment of the present invention, showing the state when the mover of the feed screw mechanism reaches the stop position after completion of the opening operation of the switch. It is the figure shown.

FIG. 4 is a front view showing a partial cross-section of the structure of a main part of a conventional switch operating device.

5A and 5B are views showing the arrangement of limit switches when viewed from the Z1 direction and the Z2 direction of FIG. 4, respectively.

[Explanation of symbols]

 1 Screw rod 5 Mover 7 Motor 12 Roller 13 Spindle 14 Arm LS11 Open circuit operation completion detection limit switch LS12 Open circuit operation motor stop limit switch LS21 Closing operation completion limit switch LS22 Circuit closing operation motor stop limit switch

Claims (2)

[Claims] 1. A screw rod having a main shaft directly connected to an operating shaft of a switch or through a connecting mechanism, a screw rod driven by an electric motor, and a female screw screwed to the screw rod. In a switch operating device including a feed screw mechanism including a mover that is linearly displaced with rotation, and a conversion mechanism that converts a linear motion of the mover into a rotary motion and transmits the rotary motion to the spindle. Immediately after the mover drives the limit switch for operation completion detection, which is driven by the mover to perform a detection operation when the mover reaches a position for completing the operation of the switch. A motor stop limit switch for generating a command signal for instructing to stop the motor driven by the mover,
A switch operating device, which is arranged side by side in a direction parallel to the axis of the screw rod. 2. A screw shaft having a main shaft connected directly to an operating shaft of a switch or through a connecting mechanism, a screw rod driven to rotate by an electric motor, and a female screw screwed to the screw rod. In a switch operating device including a feed screw mechanism including a mover that is linearly displaced with rotation, and a conversion mechanism that converts a linear motion of the mover into a rotary motion and transmits the rotary motion to the spindle. When the mover reaches a position to complete the opening operation of the switch, it is driven by the mover to perform a detection operation, and a limit switch for detecting the completion of the opening operation, and the mover includes a limit switch for detecting the completion of the opening operation. Immediately after driving, a limit switch for stopping the electric motor at the time of open circuit, which generates a command signal for instructing to stop the electric motor by being driven by the mover, and the mover performs the closing operation of the switch. And a closing switch for detecting the closing of the closing operation, which is driven by the mover to perform a detecting operation when the position reaches the closing position, and is driven by the moving piece immediately after the mover drives the closing switch for detecting the closing operation And a limit switch for stopping the electric motor during closing operation that generates a command signal for instructing to stop the electric motor by arranging them in a direction parallel to the axis of the screw rod.