JPH0850049A - Level switch - Google Patents

Abstract

PURPOSE:To omit a spring between a float, which is liable to be damaged by the rotation of the float, and stopper, by providing a magnet, which has the magnetic repelling force with respect to a magnet provided on the float, at a stopper for preventing the float from coming off. CONSTITUTION:A lead switch 49 is embedded in a float 45 and opened and closed by the approach and separation of a magnet 8 and detects the surface of the liquid. An annular magnet 51 is embedded in the surface of the float 45 facing a stopper 46. An annular magnet 52 is provided in the surface of the stopper 46 facing the magnet 51. The polarity of the surface of the magnet 52 facing the float 45 has the same polarity of the surface of the magnet 51 facing the stopper 46. Thus, the magnets 51 and 52 generate the magnetic repelling forces repelling each other. The repelling forces act in the separating direction of the float 45 and the stopper 46. Since the shapes of the magnets 51 and 52 both have the annular shape, the repelling forces are not changed even if the float 45 is rotated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a level switch used in an accumulator device of a control rod drive water pressure device of a boiling water reactor.

[0002]

2. Description of the Related Art The output control of a boiling water reactor is performed by inserting and pulling out control rods in addition to the flow rate control by a coolant. Also, in an emergency, insert the control rod in an emergency.
Shut down the reactor.

The control rod drive mechanism inserts and pulls out the control rod. A plurality of control rod drive mechanisms are installed in the reactor in correspondence with the number of control rods to be inserted into and extracted from the reactor core, and the control rod drive mechanism operates by supplying drive water from each control rod drive water pressure device. Further, in the event of an emergency, the control rod drive mechanism urgently inserts the control rod into the core portion by supplying the high-pressure water stored in the accumulator device of the control rod drive water pressure device.

FIG. 4 shows a concrete example of the structure of the control rod drive water pressure device described above. This control rod drive water pressure device 1 is provided with an accumulator device 2 and a switching device 3.
The accumulator device 2 is connected to the insertion pipe 6 via a valve 4 and a scrum valve 5, and a control rod drive mechanism (not shown) is connected to the tip of the insertion pipe 6.
A filling water pipe 8 is connected to the pipe 7 between the scrum valve 5 and the accumulator device 2.

The accumulator device 2 includes an accumulator 10, a gas container 11, and a pipe 1 for connecting them.
2 and an instrumentation unit 13 inserted in the pipe 12.

The accumulator 10 has an end plate 2 at the upper and lower ends.
It is composed of a cylinder 23 closed by 1, 22 and a piston 24 inserted in the cylinder 23 so as to be vertically movable. A gas chamber 26 formed between the end plate 22 and the piston 24 has a gas chamber 26. The pipe 12 is connected.

The instrumentation unit 13 includes a level switch 31 and a valve 3 provided between the pipe 12 and the gas inlet 30.
2 and a pressure switch 33 connected between the gas inlet 30 and the valve 32.

As shown in FIG. 5, the level switch 31 has a switch body 40 composed of a body upper portion 41 and a body lower portion 42, a base end thereof connected to the body upper portion 41, and a tip of a convex portion of the body lower portion 42. Recess 43 formed inside 43a
a guide pipe 44 inserted in b, a float 45 fitted to the convex portion 43a of the lower body 42 so as to be vertically movable,
A stopper 46 attached to the tip of the convex portion 43a of the lower body 42 for preventing the float 45 from falling off the convex portion 43a, the stopper 46 and the float 4
5, a spring 47 that is interposed between the float 45 and the float 45 and generates a spring force in a direction in which the float 45 and the float 46 are separated from each other;
It is roughly composed of.

The spring 47 includes a float 45 and a stopper 46.
By reducing the risk that the float 45 will not rise even if the water surface reaches the float 45, and when the water surface reaches the float 45, by promoting the float 45 to rise, The level switch 31 is provided to enable quick detection of water. The spring 47 in a state where the water surface does not reach the float 45 is held in a contracted state by the weight of the float 45.

The float 45 is made of a material or structure having a specific gravity smaller than that of water, and has a first magnet 48 embedded therein. Further, protrusions 45a and 45b are provided on the upper portion of the float 45, which prevents the float 45 itself from being in contact with the lower flat surface 43c of the lower portion 42 of the main body.

A reed switch 49 is built in the guide pipe 44. As a result, when the first magnet 48 embedded in the float 45 approaches the reed switch 49, the reed contact of the reed switch 49 is closed by the magnetic force of the first magnet 48 itself, and as a result, the position of the float 45 changes. To be detected.

In the above apparatus, the water chamber 25 of the accumulator 10 stores water necessary for driving the control rod drive mechanism in an emergency, and the gas container 11 stores the water in the accumulator 10. A gas having the pressure necessary to supply the control rod drive mechanism is stored.
The pressure inside the gas container 11 is set lower than the water pressure from the filling water pipe 8.

The scrum valve 5 is normally closed, so that the piston 24 in the accumulator 10 is closed.
Is constantly pressed against the lower end plate 22 by the water pressure from the filling water pipe 8 to compress the gas in the gas container 11 and to supply the accumulator 10 with a necessary amount of water in an emergency.
Is stored in.

Further, the piston 2 in the accumulator 10
Water leakage from 4 is monitored by a level switch 24, while gas container 11, piston 24, cylinder 21
Gas leakage from the welded portion between the end plate 22 and the end plate 22 or the seal portion of the instrumentation unit 13 is constantly monitored by the pressure switch 33 to secure water and gas at a pressure necessary in an emergency.

[0015]

In the control rod drive water pressure device constructed as described above, when inspecting the accumulator device 2 during the periodic inspection, the plug (not shown) of the gas inlet 30 is removed and the valve is opened. Although the gas is discharged by opening the valve 32, the level switch 31 is on the flow path of the exhaust gas. Therefore, when the exhaust gas has a strong momentum, a gas flow in the cross-sectional direction is generated around the float 45. When the lateral component of the gas flow is unbalanced, a rotational force is generated in the float 45, which may damage the spring 47.
When the spring 47 is damaged, even if the water surface reaches the float 45, the force for raising the float 45 is reduced by the spring force of the spring 47 itself. The detection cannot be performed quickly, and the float 45 itself has a stopper 46.
If it sticks to the float 45, the float 45 itself is lifted until the float 45 itself generates a floating force equal to or more than the force for releasing the sticking between the float 45 and the stopper 46 (hereinafter, referred to as sticking force). However, there was a problem that the water surface could not be detected quickly as a result.

[0016]

In order to solve the above-mentioned problems, claim 1 of the present invention provides a reed switch installed in a main body, and the main body penetrates through the reed switch to move up and down along the main body. The float, a first magnet attached to the float to actuate the reed switch, and a stopper connected to one side of the body to prevent the float from falling off. Is provided with a second magnet, and the stopper is provided with a third magnet having a magnetic repulsive force with respect to the second magnet.

According to a second aspect of the present invention, in the level switch according to the first aspect, the first magnet and the second magnet provided on the float are composed of one magnet. It is characterized by

According to a third aspect of the present invention, a reed switch installed in the main body, a float penetrating the main body and moving up and down along the main body, and the float for reacting the reed switch. And a stopper connected to one side of the main body to prevent the float from falling off. The float is provided with a bottomed hole on the surface facing the stopper. It is characterized by

[0019]

In the level switch according to the first to third aspects of the present invention, even if a lateral force component of the gas flow around the float causes an imbalance and a rotational force is generated in the float and the float rotates, the float switch does not work. Since no spring is provided between the float and the stopper, there is no problem caused by damage to the spring as in the conventional case.

Further, in the level switch according to any one of claims 1 and 2, the float is provided with a second magnet, and the stopper has a magnetic repulsive force with respect to the second magnet. Since the attached third magnet is provided, the repulsive force acts on the float in addition to the above-mentioned floating force, so that the float rapidly rises by the amount of the repulsive force. Further, if a floating force, which is a force obtained by subtracting the repulsive force from the sticking force, is generated in the float itself by the action of the repulsive force, the sticking between the float and the stopper is released.

Further, the level switch according to claim 3 is
When the water surface rises to reach the float, air is trapped in the bottomed hole provided on the surface of the float facing the stopper. Therefore, when the water surface reaches the float, in addition to the floating force of the float itself, the floating force of the air trapped in the bottomed hole acts on the float. Rises quickly. Further, since the levitation force by the air acts, if the levitation force of the force obtained by subtracting the levitation force by the air from the adhesion force is generated in the float itself, the adhesion between the float and the stopper is released.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the level switch of the present invention is shown in FIG.
Will be explained. FIG. 1 shows the overall structure of a level switch 50 which is an embodiment of the present invention. In FIG. 1, the same components as those of the conventional level switch 31 shown in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted.
Further, the reed switch 49 of this embodiment is the float 45.
Since the first magnets 48 embedded in are opposed to each other, they are normally closed, and when the magnets 48 are separated upward, they are opened to detect the liquid surface.

An annular second magnet 51 is embedded in the surface of the float 45 facing the stopper 46.

On the surface of the stopper 46 facing the second magnet 51 provided on the float 45, an annular third magnet 52 is provided. The polarity (N pole / S pole) of the surface of the third magnet 52 facing the float 45 is the same as that of the second magnet 51 described above.
The polarity is the same as the polarity of the surface facing the stopper 46. As a result, the second magnet 51 and the third magnet 52 magnetically generate repulsive force (magnetic force),
This repulsive force acts in a direction in which the float 45 and the stopper 46 are separated from each other. Further, since the second magnet and the third magnet 52 are both annular in shape, the repulsive force does not change even if the float 45 rotates.

The level switch 50 formed in this way
In the above, in the horizontal component of the gas flow around the float 45, an imbalance occurs and a rotational force is generated in the float 45, a rotational force is generated in the float 45 itself, and even if the float 45 rotates, Stopper 4
Since no spring is provided between the spring 6 and 6, there is no problem caused by damage to the spring as in the conventional case.

The stopper 46 is provided with a third magnet, and the float is provided with a second magnet having a magnetic repulsive force with respect to the third magnet. The above-mentioned repulsive force acts in addition to the above-mentioned levitation force. Therefore, if a floating force of a force obtained by subtracting the above-mentioned repulsive force from the above-mentioned sticking force is generated in the float 45, the float 45 and the stopper 46 will be stuck together. Can be released, and after the sticking is released, the float 45 can be quickly raised by this repulsive force.

The maximum value of the magnetic force as the repulsive force generated between the second magnet 51 and the third magnet 52 is the weight of the float 45, the first magnet 48 and the second magnet 51. It is preferable that the magnetic force is larger than the total weight of the two. In this way, even if the water surface does not reach the float 45, the float 4
5 and the stopper 46 are kept in a separated state, the sticking of the float 45 and the stopper 46 can be completely eliminated.

Further, the float 45 of this embodiment has the first magnet 4 for operating the reed switch 49.
8 and the second magnet 51 are provided in total, but one magnet A is provided in the portion shown by the dotted line in FIG. 1, and this magnet A has the functions of the above two magnets 48 and 51. You may allow it. In this case, it is preferable that the reed switch 49 is normally opened and is closed only when the first magnet 48 embedded in the float 45 is close to detect the liquid level.

Further, by making the shapes of the second magnet 51 provided on the float 45 and the third magnet 52 provided on the stopper 46 both annular, the second magnet 51 is rotated even if the float 45 rotates. The repulsive force between the third magnet 52 and
The present invention is not limited to this. For example, even if only one of the second magnet 51 and the third magnet 52 is an annular magnet, the repulsive force between the second magnet 51 and the third magnet 52. Can be constant.

Next, a second embodiment of the level switch of the present invention will be described with reference to FIGS. FIG. 2 is a vertical sectional view of a level switch 60 which is an embodiment of the present invention.
FIG. 3 is a sectional view taken along line AA of FIG. Level switch 6
1 is not shown in FIG. 2 and FIG.
Is the same as 2 and 3, the same components as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

An annular bottomed hole 61 is provided on the surface of the float 45 facing the stopper 46. As a result, the tip end surface 62A of the annular convex portion 62 on the inner peripheral side of the float 45 comes into contact with the stopper 46.

The level switch 60 constructed in this way
In the above, in the horizontal component of the gas flow around the float 45, an imbalance occurs and a rotational force is generated in the float 45, a rotational force is generated in the float 45 itself, and even if the float 45 rotates, Stopper 4
Since no spring is provided between the spring 6 and 6, there is no problem caused by damage to the spring as in the conventional case.

When the water surface rises and reaches the float 45, air is trapped in an annular bottomed hole 61 provided on the surface of the float 45 facing the stopper 46. Therefore, when the water surface reaches the float 45,
In addition to the levitation force of the float 45 itself, the levitation force of the air trapped in the annular bottomed hole 61 acts on the float 45. Therefore, the levitation force of the air is subtracted from the sticking force. If the floating force is generated in the float 45, the sticking between the float 45 and the stopper 46 can be released, and after the sticking is released, the float 4 is lifted by the floating force by the air.
5 can be raised quickly.

Further, in this embodiment, since the contact surface between the float 45 and the stopper 46 is only the tip surface 62A of the annular convex portion 62 on the inner peripheral side of the float 45, as seen in the conventional level switch. The contact surface area is smaller than the contact surface between the float 45 and the stopper 46. For this reason, the sticking force between the float 45 and the stopper 46 can be reduced by the amount that the area of the contact surface is reduced, and as a result, the sticking between the float 45 and the stopper 46 can be released with a small force. be able to. As is apparent from the above, it goes without saying that the smaller the area of the front end surface 62A, the smaller the sticking force between the float 45 and the stopper 46.

The level switch 60 of this embodiment is provided with an annular bottomed hole 61 on the surface of the float 45 facing the stopper 46. Although the float 45 can be quickly raised, the shape of the bottomed hole 61 does not have to be annular, and for example, a circular or quadrangular bottomed hole may be provided. In this case, the more circular or square bottomed holes are provided, the larger the volume of air in the bottomed holes becomes, and the larger the levitation force becomes. Become.

[0036]

As described above, the first aspect of the present invention according to the present invention is as follows.
According to the level switch of claim 3, the lateral component of the gas flow around the float is unbalanced, the rotational force is generated in the float, the rotational force is generated in the float itself, and even if the float is rotated, it is originally. Since no spring is provided between the float and the stopper, there is no problem caused by damage to the spring as in the conventional case.

Further, in the level switch according to any one of claims 1 and 2, the float is provided with a second magnet, and the stopper is a third magnet having a magnetic repulsive force against the second magnet. Since the magnet is provided, the repulsive force acts on the float in addition to the above-mentioned floating force, so that the float can be quickly raised by this repulsive force. Further, if the floating force, which is a force obtained by subtracting the repulsive force from the sticking force, is generated in the float by the action of the repulsive force, the sticking between the float and the stopper can be released.

A level switch according to a third aspect of the invention is
When the water surface rises and reaches the float, air is trapped in the bottomed hole provided on the surface facing the stopper of the float. Therefore, when the water surface reaches the float, in addition to the floating force of the float itself, the floating force of the air trapped in the bottomed hole acts on the float. Can be raised quickly. Further, since the levitation force due to the air acts, if a levitation force of a force obtained by subtracting the levitation force due to the air from the sticking force is generated in the float,
The sticking of the float and the stopper can be released.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a first embodiment of a level switch according to the present invention.

FIG. 2 is a vertical sectional view of a second embodiment of the level switch of the present invention.

3 is a cross-sectional view taken along the line AA of the level switch shown in FIG.

FIG. 4 is a diagram showing a specific configuration example of a control rod drive hydraulic device in which the level switch of the present invention is used.

FIG. 5 is a vertical sectional view of an example of a conventional level switch.

[Explanation of symbols]

 31, 50, 60 Level switch 40 Main body 41 Main body upper part 42 Main body lower part 44 Guide pipe 45 Float 46 Stopper 47 Spring 48 First magnet 51 Second magnet 52 Third magnet 61 Bottomed hole

Claims (3)

[Claims] 1. A reed switch installed in the main body, a float penetrating the main body, and moving up and down along the main body, and a first magnet attached to the float for reacting the reed switch. And a stopper that is connected to one side of the main body and prevents the float from falling off, the float is provided with a second magnet, and the stopper is provided with a magnet for the second magnet. A level switch characterized in that a third magnet having a repulsive force is provided. 2. The level switch according to claim 1, wherein the first magnet and the second magnet provided on the float are composed of one magnet. 3. A reed switch installed in the main body, a float penetrating the main body, and moving up and down along the main body, a magnet attached to the float for reacting the reed switch, A stopper connected to one side of the main body for preventing the float from falling off; and the float having a bottomed hole on a surface facing the stopper. switch.