JPS621429Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a protection circuit for a pneumatic circuit that operates infrequently, and is improved to improve the reliability of the pneumatic circuit that operates infrequently.

FIG. 1 shows a conventional example of a low-frequency operation pneumatic circuit that operates the guide vanes of a power generation water turbine. In this conventional example, an electric motor drives an actuator connected to a guide vane that adjusts the amount of water supplied to a power generation water turbine.When the electric motor stops due to a power outage, etc., the actuator is moved by a pneumatic circuit. This closes the guide vanes and stops power generation. More specifically, referring to FIG. 1, a feed nut 1 connected to a guide vane of a power generation water turbine (not shown) has a guide groove 1a formed in its axial direction, while a guide frame 2 has a guide groove 1a formed therein.
A guide protrusion 2a is formed which fits into the guide nut 2a and restrains the rotation of the feed nut 1. Therefore, the guide projection 2a fits into the guide groove 1a, and the feed nut 1 is slidably supported on the guide frame 2. The forward end of the feed screw shaft 3, which is formed with a male thread, is screwed into the feed nut 1, and the base end thereof is rotatably supported by a bearing 5 attached to a support base 4. Further, the base end of the feed screw shaft 3 is connected to an electric motor 7 via a plurality of reduction gears 6. Therefore, in the actuator composed of the feed nut 1 and the feed screw shaft 3, the rotation of the feed screw shaft 3 rotated by the electric motor 7 causes the feed nut 1 to perform reciprocating linear movement to open and close a guide vane (not shown). I'm starting to do it. On the other hand, a pneumatic motor 8 is directly connected to the electric motor 7. Furthermore, this pneumatic motor 8 is connected via an air supply path 9 to a pneumatic tank 10 which is a pneumatic source in which compressed air is stored. The air supply path 9 is closed during normal times, that is, when the electric motor 7 and its power source (not shown) are connected, and is open during a power outage, that is, when the electric motor 7 and its power source are cut off. Solenoid valve 1
1 is interposed. Furthermore, two pressure reducing valves 12 are interposed in the air supply path 9 in order to prevent damage to the solenoid valve 11 due to sudden changes in air pressure. Further, a speed controller 13 is connected to the exhaust port side of the pneumatic motor 8 to adjust the rotational speed of the pneumatic motor 8 by adjusting the amount of compressed air exhausted. In addition, in the figure, 10a is a manual valve of the pneumatic tank 10, 14
is a silencer.

Therefore, when the operation of the electric motor 7 stops due to a power outage, the solenoid valve 11 opens and the compressed air in the pneumatic tank 10 flows into the pneumatic motor 8, causing the pneumatic motor 8 to rotate and the electric motor 7 to be forced into operation. Since the feed screw shaft 3 rotates and the feed nut 1 moves, the guide vanes are closed and the generator (not shown) is stopped. Note that the solenoid valve 11 used in this conventional example is closed when energized and opened when not energized.
1 and the electric motor 7 can be used in common. This results in a simpler structure.

However, in such conventional technology, the situation where the actuator is operated by the pneumatic motor 8 due to a power outage occurs only once a year or more often, so there is a risk that the solenoid valve 11 may become stuck due to rust or the like and become inoperable. It was hot. Therefore, in order to prevent the solenoid valve 11 from sticking, it was necessary to perform an operation test of the solenoid valve 11 once a week to once a month with the manual valve 10a closed. Furthermore, in order to ensure the desired operation, the solenoid valve 11 had to be a low-frequency solenoid valve.

SUMMARY OF THE INVENTION In view of the above-mentioned prior art, it is an object of the present invention to provide a protection circuit for a pneumatic circuit that operates infrequently, which prevents the electromagnetic valve of the pneumatic circuit that operates infrequently from sticking and improves reliability. The configuration of the present invention to achieve such an object is to use the electric motor as a drive source during a power outage for an actuator consisting of a feed screw shaft that is connected to an electric motor and rotates, and a feed nut that makes reciprocating linear movements due to the rotation of the feed screw shaft. A pneumatic motor that is directly connected to the pneumatic motor and an air supply path that supplies compressed air from a pneumatic source to the pneumatic motor are connected in series, and both are normally closed when the electric motor and its power source are connected. In a low-frequency operation pneumatic circuit having two solenoid valves that are both opened at the time of a power outage and shut off, two switches individually connected to the solenoid valves are connected in the direction of the reciprocating linear movement of the feed nut. It is characterized in that the solenoid valve is disposed at different positions and is alternately closed by the reciprocating linear movement of the feed nut to open the solenoid valve during normal operation.

Embodiments of the present invention will be described in detail below with reference to the drawings. Note that parts that are the same as those in the prior art are given the same numbers and redundant explanations will be omitted.

FIG. 2 shows an embodiment of the invention. As shown in the figure, the air supply path 9 has two solenoid valves 11 and 11a.
are inserted in series. These solenoid valves 11,1
1a is normally closed when the electric motor 7 and a power source (not shown) are connected, and is open during a power outage when the electric motor 7 and the power source are cut off. The feed nut 1 that makes a reciprocating linear motion is equipped with a cam 15, and two limit switches 16, 16a are arranged at two different points in the direction of the reciprocating linear movement of the feed nut 1 and contact the cam 15 alternately. It's becoming like that. and the limit switch 1
6 and 16a are individually connected to electromagnetic valves 11 and 11a. Therefore, under normal conditions, the feed nut 1 is linearly reciprocated by the electric motor 7, and when the cam 15 contacts the limit switch 16 and the limit switch 16 is turned on, the solenoid valve 11 opens, and the cam 15 contacts the limit switch 16a. When the lever limit switch 16a is turned on, the solenoid valve 1
1a is open. That is, the solenoid valve 11 and the solenoid valve 11a
and operate alternately. Needless to say, at this time, at least one of the solenoid valve 11 and the solenoid valve 11a is closed. In addition, in the event of a power outage, solenoid valve 1
It goes without saying that 1 and 11a are both open.

As specifically explained above in conjunction with the embodiments, according to the present invention, two switches individually connected to each solenoid valve move in a reciprocating straight line so that the two solenoid valves are actuated when turned on. Since the feed nut allows the feed to be fed alternately,
As a result of the solenoid valve being operated without operating the pneumatic motor during normal operation, the solenoid valve can be prevented from sticking due to a simple structure and reliability is improved.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing a conventional example of a low-frequency operation pneumatic circuit that operates the guide vanes of a power generation water turbine;
The figure is a schematic diagram showing an embodiment of the present invention. In the drawing, 1 is the feed nut, 3 is the feed screw shaft, and 7 is the feed nut.
is an electric motor, 8 is a pneumatic motor, 9 is an air supply path, 1
0 is a pneumatic tank, 11, 11a is a solenoid valve, 16,
16a is a limit switch.

Claims (1)

[Scope of utility model registration request] A pneumatic motor directly connected to the electric motor as a drive source during a power outage for an actuator consisting of a feed screw shaft connected to an electric motor for rotational movement and a feed nut for reciprocating linear movement due to the rotation of the feed screw shaft; It is installed in series in an air supply path that supplies compressed air from a pneumatic source to a motor, and when the electric motor and its power source are connected, both are closed and cut off during a power outage. In a low frequency operating pneumatic circuit having two solenoid valves that are open, two
The solenoid valve is characterized in that two switches are disposed at different positions in the direction of the reciprocating linear movement of the feed nut, and are alternately closed by the reciprocating linear movement of the feed nut to open the solenoid valve in normal times. Protection circuit for frequency operated pneumatic circuits.