JP2000025028A - Producing device for cement slurry, powder valve, liquid valve, and detector for height of liquid level - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a producing device for cement slurry in which charge and transfer of water, cement and cement slurry are automated and also quality of cement slurry is stabilized. SOLUTION: The mixer part 1600 of the producing device 1000 for cement slurry is equipped with a mixer 1602, a level switch 1604 and a mixer valve 1606. The mixer 1602 is equipped with a first tank and a second tank in which water and cement are agitated and cement slurry is manufactured. A pipeline supplying cement slurry from the first tank to the second tank is provided. The mixer valve 1606 for performing opening and closing of the pipeline is provided. The mixer valve is opened, closed and controlled by a control signal sent from a cement slurry control panel 2000. Cement slurry is continuously manufactured in the first tank and the second tank and supplied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cement slurry producing apparatus for producing a cement slurry by stirring cement and water, and a powder valve, a liquid valve and a liquid level suitable for such a cement slurry producing apparatus. Related to the detector.

[0002]

2. Description of the Related Art Conventionally, there is a cement slurry producing apparatus for producing cement slurry by stirring cement and water using a two-tank mixer. The two-tank type mixer is composed of an upper tank and a lower tank which are arranged vertically, a pipe connecting the upper tank and the lower tank,
A mixer valve for opening and closing the pipe is provided. As a production procedure of a cement slurry, first, a cement slurry is prepared by putting measured cement and water into an upper tank and stirring. The cement slurry produced in the upper tank is charged into the lower tank from the upper tank by manually opening the mixer valve. The cement slurry put into the lower tank is pumped from the lower tank to a supply destination by a slurry pump or the like.

[0003] When the cement slurry in the upper tank is empty, the above valve is manually closed, and the cement and water are put into the upper tank and stirred to form a cement slurry. Save in.
When the cement slurry in the lower tank becomes empty, the cement slurry is supplied from the upper tank to the lower tank in the same procedure. Such a procedure is sequentially repeated. In addition, when the cement is put into the upper tank of the mixer, a mixer valve provided in a pipe communicating between the cement silo storing the cement and the upper tank of the mixer is manually opened and closed. In addition, when pouring water into the upper tank of the mixer, water is supplied from the water tank storing water to the upper tank of the mixer by a submersible pump. We measure the amount of water we make based on visual measurements.

[0004]

In the above-mentioned conventional cement slurry manufacturing apparatus, first, the step of putting cement into the upper tank and the step of putting water into the upper tank are performed manually. Had the following problems. That is, in the step of putting cement, since the cement bag carried in a bag unit of 25 kg per bag was manually opened and put into the upper tank each time, heavy labor was forced. , It was troublesome. Further, the opened cement bag becomes a large amount of construction waste, which is not preferable in terms of environmental protection.
Further, when the powder is put into the upper tank, considerable dust is generated, which is not preferable as a working environment. It is desirable to automate the process as a method for solving the problems of the above process. For this reason, automation can be considered by supplying small quantities of bulk cement to the cement hopper in small batches using a small cement silo instead of cementing in bags, but even in that case, the following problems common to manual work are considered. We have to solve it. That is, the moisture or repellent water generated by stirring with the water charged into the upper tank of the two-tank mixer and the cement dust adhere and grow around the powder valve during a long operation, and This also hindered the normal and reliable operation of the body valve. In the past, there was no suitable powder valve that could operate stably against such phenomena. In such a case, the original slurry production operation was temporarily suspended and the adhered material was manually removed. Was. Therefore, there was a remarkable decrease in work efficiency. Next, in the process of pouring water into the upper tank, the worker had to open and close the water pipe valve while visually checking the scale. It is difficult to stabilize the mixing ratio between the cement and the cement, that is, to accurately control the quality of the cement slurry. Secondly, in any of the upper tank for producing the cement slurry by stirring the supplied cement and water, and in the lower tank for receiving and temporarily storing the cement slurry produced by stirring and supplying to the supply destination, There has been no liquid level detector capable of operating accurately with respect to the flow phenomenon of the cement slurry liquid surface caused by stirring, the increase in viscosity of the cement slurry caused by the passage of time, and the phenomenon of adhesion and solidification. More specifically, in a float type liquid level detector conventionally used, the float constantly swings near its control level due to the flow of the liquid surface accompanying agitation. There were many things. Further, in a rod-shaped liquid level detector such as a conventionally used electrode type, during a long operation, cement slurry adheres to the surface of the rod-shaped detector and solidifies and grows,
The resistance value of the detector deviates from the normal state,
There was a problem that accurate level information could not be obtained. Furthermore, even in non-contact type detectors such as ultrasonic type or laser type, a lot of cement slurry bubbles are generated by the entrainment of air on the liquid surface to be measured originally, and sound or light is generated on the surface of the bubbles. Is reflected, so it is difficult to know the accurate liquid level. Third, when the cement slurry is sent from the upper tank to the lower tank and from the lower tank to the supply destination, there is no liquid valve that can properly operate the cement slurry having a property of increasing viscosity and solidifying and adhering. Was. The present invention has been devised in view of the above-mentioned circumstances, and an object of the present invention is to solve the above-mentioned problems by fully manufacturing a required amount in small batches continuously in a batch unit for a long time. It is an object of the present invention to provide a possible cement slurry production apparatus.
Another object of the present invention is to provide a powder valve, a liquid valve, and a liquid level detector suitable for such a cement slurry manufacturing apparatus.

[0005]

According to a first aspect of the present invention, there is provided a cement slurry producing apparatus including a cement supply unit, a water supply unit, a mixer, and a control unit. A fixed amount of cement is measured and stored, and the measured predetermined amount of cement is charged into the mixer.The water supply unit is configured to measure and store a predetermined amount of water and measure the predetermined amount of water. Into the mixer, the mixer has a first tank, a second tank, and a liquid level detector, and the first tank is charged from the cement supply unit. A predetermined amount of cement and a predetermined amount of water supplied from the water supply unit are stirred to form and store a cement slurry, and the second tank is configured to store the cement slurry supplied from the first tank. When you stir and store In addition, it is configured to supply the stored cement slurry to a supply destination, and the liquid level height detector determines whether the liquid level of the cement slurry in the second tank is equal to or less than a predetermined position. When the liquid level sensor detects that the position of the liquid level of the cement slurry in the second tank has become equal to or less than a predetermined position, the control device controls the first tank. Into the second tank, instructing the cement supply unit to measure a predetermined amount of cement, and instructing the water supply unit to measure a predetermined amount of water, and measuring the cement and water. After completion, the predetermined amount of cement is supplied from the cement supply unit to the first tank, and the predetermined amount of water is supplied from the water supply unit to the first tank. Features. Further, the present invention is characterized in that the cement slurry is a refractory coating spraying material used in construction work. Further, the present invention is a powder valve provided at a powder discharge port of a hopper for storing powder and controlling discharge of the powder, wherein a rubber forming a pipeline connected to the powder discharge port is provided. A chute and an opening / closing means configured to close the pipeline by sandwiching an intermediate portion of the rubber chute from the outside of the rubber chute and open the pipeline by releasing the sandwiching. Features. Further, according to the present invention, the opening / closing means includes a first arm, a second arm, a link mechanism, and a driving means, and one end of the first arm and the second arm is pivotally connected to the main body of the hopper. The other end has a pressing portion for pressing the rubber chute at the other end, and the pressing portion is disposed at a position sandwiching the rubber chute.
An arm and a second arm are connected to open and close the pressing portions, and the driving unit opens and closes the pressing portions by applying a driving force to the first arm and the second arm. The closing of the pipeline by the opening and closing means is performed by closing the pressing portion,
The opening of the conduit by the opening / closing means is performed by opening the pressing portion. Further, the present invention is a liquid valve provided at a liquid discharge port of a liquid tank for storing liquid and controlling the discharge of the liquid, comprising a stopper, an urging member, and a driving unit, wherein the stopper is provided. Is disposed inside the liquid tank so as to be movable along an axis passing through the center of the liquid discharge port between a closed position for closing the liquid discharge port and an open position for opening the liquid discharge port, and the biasing member is The stopper is configured to bias toward the closed position, and the driving unit is configured to move the stopper to the open position when activated. Further, in the present invention, a manual opening handle is connected to the stopper, and the stopper is moved to the closed position by moving the manual opening handle against the urging force of the urging member. From the open position to the open position. Further, the invention is characterized in that the driving means is an air cylinder. Further, the present invention is a liquid level detector for detecting the liquid level of the flowing liquid, comprising a pendulum member and a limit switch, wherein the pendulum member is located above the liquid level. In, the portion facing the liquid surface of the liquid is supported so as to be swingable along the flow direction of the liquid, and the portion facing the liquid surface of the liquid is in the first position in a state where it is not immersed in the liquid. The liquid crystal display device is configured to be positioned and to be swung to a second position by the flow of the liquid in a state where the portion facing the liquid surface of the liquid is immersed in the liquid. It is characterized in that it is configured to output an opening / closing signal in conjunction with swinging to the second position. Further, according to the present invention, the limit switch includes a main body, a movable piece that advances and retreats from the main body, and an urging member, wherein the movable piece is urged in a predetermined direction by the urging member. Is configured to turn on and off by being moved back and forth,
The movable piece and the pendulum member are connected, and the pendulum member is configured to move the first pendulum member by the urging force of the urging member.
It is configured to be located at a position. Further, the present invention is characterized in that the first position is a position where the pendulum member is located by an urging force of an urging member built in the limit switch. Further, the present invention is characterized in that a stirring means for flowing the liquid is provided, and the opening / closing signal is made valid only during a period when the stirring means is performing the stirring operation.

[0006] In the cement slurry production apparatus of the present invention,
When the position of the liquid level of the cement slurry in the second tank falls below a predetermined position, the cement slurry in the first tank is
It is put into the tank. Then, the cement supply unit is instructed to measure a predetermined amount of cement, and the water supply unit is instructed to measure a predetermined amount of water. After the measurement of the cement and the water is completed, a predetermined amount of the cement is supplied from the cement supply unit to the first tank, and a predetermined amount of the water is supplied to the first tank from the water supply unit. Therefore, the cement slurry is continuously produced and supplied in the first tank and the second tank. In the powder valve of the present invention, the pipeline formed by the rubber chute is opened and closed by the opening and closing means. In the liquid valve according to the aspect of the invention, the stopper moves along the axis passing through the center of the liquid outlet between the closed position that closes the liquid outlet and the open position that opens the liquid outlet inside the liquid tank. Open and close the outlet. In the liquid level detector of the present invention, the pendulum member is swung from the first position to the second position by the flowing liquid to output an open / close signal.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a cement slurry producing apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a cement slurry producing apparatus according to the present invention, FIG. 2 is an explanatory view showing a configuration of a powder valve, FIG. 2 (A) shows a valve closed state, and FIG. B) shows a valve open state. FIG. 3 is an explanatory view showing the configuration of the liquid valve, and FIG. 3 (A) shows the valve closed state.
(B) shows a valve open state. 4A and 4B are explanatory diagrams showing the configuration of the liquid level detector, wherein FIG. 4A shows a detection state and FIG. 4B shows a non-detection state. FIG. 5 is an operation flowchart illustrating an automatic operation preparation operation of the cement slurry manufacturing apparatus, and FIG. 6 is an operation flowchart illustrating an automatic operation operation of the cement slurry manufacturing apparatus.

First, a schematic configuration of a cement slurry producing apparatus will be described with reference to FIG. The cement slurry manufacturing apparatus 1000 includes a cement supply unit 1200 for supplying cement, a water supply unit 1400 for supplying water,
A mixer section 1600 for producing cement slurry by stirring cement and water, and a cement slurry supply section 1800 for supplying cement slurry to a supply destination are provided.

The cement supply unit 1200 includes a cement tank 1202, a level switch 1204, a horizontal screw conveyor 1206, a vertical screw conveyor 1208,
Measuring hopper 1210, load cell 121 for measuring cement
2. A cement discharge valve (powder valve) 1214 and a cement silo control panel 1216 are provided.

A cement tank 1202 is for storing cement, and is a level switch 1 for detecting whether or not the amount of stored cement has become equal to or less than a predetermined amount.
204 is provided. Horizontal screw conveyor 12
06, the vertical screw conveyor 1208 is for transferring the cement in the cement tank 1202 to the weighing hopper 1210.

A weighing hopper 1210 is for weighing the cement fed by the horizontal screw conveyor 1206 and the vertical screw conveyor 1208.
A cement measuring load cell 1212 for detecting the weight of the cement stored in the measuring hopper 1210 is provided. A cement discharge valve (corresponding to a powder valve in the claims) 1214 for charging cement into the first tank 1602 constituting the mixer is provided below the measuring hopper 1210.

A cement silo control panel 1216 exchanges information with a cement slurry control panel 2000, which will be described later, and inputs a detection signal of a level switch 1204 and a detection signal of a cement weighing load cell 1212, and outputs a horizontal screw conveyor 1206, Vertical screw conveyor 1
208, is configured to control the operation of the cement discharge valve 1214.

The water supply unit 1400 includes a water tank 1402, a water supply pump 1404, a measuring water tank 1406, and a water level meter 1 for measuring water.
408, a water discharge valve 1410 is provided. Aquarium 14
A water distribution pipe is connected to 02 so that water from the water distribution pipe is introduced through a float cock, and a constant amount of water is always stored by the action of the float cock. . The water supply pump 1404 is connected to the water tank 1
The water 402 is supplied to the measuring water tank 1406, and is configured to operate under the control of the cement slurry control panel 2000.

The measuring water tank 1406 is for storing a predetermined amount of water, and is provided with a water measuring water level gauge 1408. The water meter 1408 for measuring water is provided with a measuring tank 1406.
, And is configured to input a detection signal to the cement slurry control panel 2000.
Water discharge valve (corresponding to the liquid valve in the claims) 1
410 is provided in the measuring water tank 1406 to supply water from the measuring water tank 1406 to the first tank 1602 of the mixer, and is configured to be opened and closed by the cement slurry control panel 2000. I have.

The mixer section 1600 comprises a first tank (upper tank) 1602, a second tank (lower tank) 1603,
The tank is provided with level switches 1604 and 1605 for the tank and the second tank (corresponding to the liquid level detector in the claims), a mixer valve (corresponding to the liquid valve in the claims) 1606, and the like. First tank 1602 and second tank 160
Reference numeral 3 denotes that the first tank is disposed on the upper side and the second tank is disposed on the lower side, so that they are in a vertical positional relationship. Both the first tank and the second tank are configured to stir the supplied water and cement to produce a cement slurry. First tank and second tank
A pipe for supplying cement slurry from the first tank to the second tank is provided between the tank and a tank, and a mixer valve 1606 for opening and closing the pipe is provided. The mixer valve is configured to be opened and closed by a control signal from a cement slurry control panel 2000.

Level switches 1604 and 1605 are for detecting the liquid level of the cement slurry stored in the first tank 1602 and the second tank 1603, respectively. It is configured to input a detection signal to the cement slurry control panel 2000 when the following occurs. Also, the first tank 1602 and the second tank 16
A stirring device (not illustrated) (corresponding to a stirring means in the claims) is provided at 03. The stirring device is the first tank 160
2 and a stirring blade disposed on the inner bottom portion of the second tank 1603. By rotating the stirring blade, the first
The cement and the water stored inside the tank and the second tank are stirred to form a cement slurry.

The cement slurry supply section 1800 is provided with a cement slurry pump 1802 and the like.

The cement slurry pump 1802 has a second
This is for pressure-feeding the cement slurry supplied from the tank 1603 to the spray nozzle 1900 as a supply destination. The spray nozzle 1900 is configured to blow a cement slurry as a refractory coating spray material supplied by a cement slurry pump 1802 to a building.

As described above, the cement slurry control panel 2000 includes the cement supply unit 1200 and the water supply unit 140.
0, mixer section 1600, cement slurry supply section 180
0 is controlled. Plant control panel 2
002 (corresponding to the control means in the claims) is configured to exchange information with the cement slurry control panel 2000. The hand control panel 2004 is connected to the cement slurry control panel 2000 via the plant control panel 2002. And the exchange of information. Hand control panel 20
Reference numeral 04 is configured to perform manual control of the cement slurry control panel 2000 and the cement silo control panel 1216 and to display the operation status of the cement slurry control panel 2000 and the cement silo control panel 1216.

Next, the structure of the cement discharge valve 1214 will be described with reference to FIG. The cement discharge valve 1214 is provided at the powder discharge port 1210A of the weighing hopper 1210 for storing cement, and constitutes a powder valve for controlling the discharge of cement. The cement discharge valve 1214 is connected to the powder discharge port 1210 of the weighing hopper 1210.
Rubber chute 1214A forming a pipeline connected to A
An opening / closing means 1 configured to close the pipeline by pinching an intermediate portion of the rubber chute rubber chute 1214A from the outside of the rubber chute rubber chute 1214A, and to open the pipeline by releasing the pinch.
214B.

The opening / closing means 1214B includes a first arm 121
4C, the second arm 1214D, and the link mechanism 1214
E and an air cylinder 1214F which constitutes the driving means. First arm 1214C and second arm 121
4D has a pin 1214 on one end of the body of the hopper 1210.
G and 1214H, the other end has pressing portions 1214I and 1214J for pressing the rubber chute, and the pressing portions 1214I and 1214J are arranged at positions sandwiching the rubber chute 1214A.

The link mechanism 1214E includes the link arm 1
214K and pins 1214L provided at both ends thereof,
1214M. One end of the link arm 1214K is connected to the first arm 1214K by a pin 1214L.
The other end of the link arm 1214K is pivotally connected to a position located below the pin 1214H at one end of the second arm 1214D by a pin 1214M at one end of the link arm 1214G. Each is pivoted. Therefore, the link mechanism 1214E includes the first arm 1214C and the second arm 1
214D, and pressing parts 1214I and 1214 of each other.
It is configured to open and close J.

The air cylinder 1214F has a main body 1214
N, and a rod 1214O that moves forward and backward from the main body 1214N by supplying and discharging air. The main body 1214N
The rod 1214O is pivotally connected to the weighing hopper 1210 via a pin 1214P.
A portion 12 extending from the intermediate portion of the first arm 1214C in the direction perpendicular to the longitudinal direction of the first arm 1214C
It is pivoted to 14R.

Therefore, when the rod 1214O of the air cylinder 1214F protrudes from the main body 1214N and the first arm 1214C swings counterclockwise on the paper with the pin 1214G as a fulcrum, the driving force of the driving means 1214F is increased by the link arm. The second arm 121 via the 1214E
4D, the second arm 1214D
H is pivoted clockwise on the paper about the fulcrum,
4I and 1214J are closed. When the rod 1214O of the air cylinder 1214F enters the main body 1214N and the first arm 1214C swings clockwise about the pin 1214G as a fulcrum, the driving force of the air cylinder 1214F is changed to the link arm 1
The second arm 1214D is transmitted to the second arm 1214D via the pin 214E, and the second arm 1214D is swung counterclockwise on the paper with the pin 1214H as a fulcrum.
Is opened.

Next, the operation and effect of the cement discharge valve having the above configuration will be described. FIG. 2A shows that the rod 1214O of the air cylinder 1214F is
N and the first arm 1214
C and the second arm 1214D are closed by the action of the link mechanism 1214E. In other words, the pressing portions 1214I and 1214J press the rubber chute 1214A from the outside thereof to close a pipe communicating with the powder discharge port 1210A of the measuring hopper 1210 formed by the rubber chute 1214A. Therefore, the weighing hopper 1210
A predetermined amount of cement stored in the first tank 1602 of the mixer located below is prevented from being charged.

FIG. 2B shows a state in which the rod 1214O of the air cylinder 1214F is sunk into the main body 1214N, and the first arm 1214C and the second arm 121
4D is opened by the action of the link mechanism 1214E. That is, the pressing portions 1214I and 1214
The state in which J presses the rubber chute 1214A from the outside is released, and the pipeline communicating with the powder discharge port 1210A of the weighing hopper 1210 formed by the rubber chute 1214A is opened. Therefore, a predetermined amount of cement stored in the weighing hopper 1210 is supplied to the first tank 1602 of the mixer located below.

As described above, since the opening and closing of the cement discharge valve 1214 is controlled by the operation of the air cylinder 1214F, there is no need to manually control the input of cement unlike the related art. For this reason, it is possible to achieve unmanned operation in a work environment where dust easily occurs. When an electric butterfly valve or a slide gate valve is used as the cement discharge valve, the first tank 1 of the mixer may be used.
When the cement is injected into the 602, splashes of the cement slurry fly from the mixer and adhere to the valve, and the adhered cement slurry may block the valve. In contrast, the cement discharge valve 121 of the present embodiment
In No. 4, since the pipeline formed by the rubber chute is opened and closed by the opening / closing means, even if the splash of the cement slurry adheres to the rubber chute portion, the cement chute is discharged together with the cement. Because the cement slurry attached to
There is no blockage of the valve. In addition, in the cement discharge valve 1214 of the present embodiment, it is easy to increase the valve opening ratio by increasing the cross-sectional area of the pipe formed by the rubber chute. The time required for discharging can be shortened. Further, only the rubber chute may be considered as a consumable item of the cement discharge valve 1214 of the present embodiment, and there is an advantage that the cost required for the consumable item can be reduced.

Next, referring to FIG.
0, the configuration of the mixer valve 1606 will be described. Since the configuration of each valve is the same, the mixer valve 1
606 will be described as an example. Mixer valve 1606
Is a first tank 1602 of a mixer for storing cement slurry.
A liquid valve is provided at the liquid discharge port 1602B of the tank main body 1602A, and controls the discharge to the second tank 1603.

The mixer valve 1606 has a stopper 1606A.
, An urging member 1606B, and an air cylinder 1606C constituting a driving unit. The plug portion 1606A is provided inside the tank main body 1602A of the first tank.
The liquid discharge port 1202B is provided so as to be movable along an axis passing through the center of the liquid discharge port 1202B between a closed position (FIG. 3A) for closing 02B and an open position (FIG. 3B) for opening 02B. .
That is, the lower end of the first arm 1606D extending in the vertical direction is connected to the upper part of the plug 1606A,
A bent portion 1606E bent in a direction substantially perpendicular to the longitudinal direction is provided at an upper end of the first arm 1606D, and a manual opening handle 1606F is attached to the bent portion 1606E. The manual opening handle 1606F is provided at a location that can be operated from outside the tank body 1602.

The upper end of a second arm 1606G extending in the vertical direction is connected to the bent portion 1606C.
The arm 1606G is supported by upper guides 1606H and 1606I disposed outside the tank body 1602A so as to be movable in the longitudinal direction of the second arm 1606G, that is, in the vertical direction. The lower end of the second arm 1606G is connected to the air cylinder 1606C. The air cylinder 1606C has a main body 1606J and a rod 1606K that advances and retreats from the main body 1606J by supplying and discharging air. The tip of the rod 1606I is the second arm 1
It is connected to the lower end of 606G. Driving means 1606
Air is supplied / discharged to / from an air cylinder constituting C through an electromagnetic valve, and the air cylinder is operated by controlling on / off of the electromagnetic valve.

A fixing member 1606L is attached to the second arm 1606G at a location between the upper guide 1606H and the lower guide 1606I, and an outer periphery of the second arm 1606G is provided between the fixing member 1606L and the upper guide 1606H. Is provided with a biasing member 1606B composed of a coil spring. The urging member 1606B is
The fixing member 1606L is urged downward. That is,
The plug 1606A is urged by the urging member 1606B toward a closed position where the outlet 1602B is closed.

Further, a second arm 1606 is provided at a position between the lower guide 1606I and the air cylinder 1606C.
A restricting member 1606M is attached to G, and when the restricting member 1606M contacts the lower part of the lower guide 1606I, the projecting position of the rod 1606K of the driving means 1606C is restricted. Therefore, when the air cylinder 1606C is inactive, the rod 160
6K is applied to the main body 160 by the urging force of the urging member 1606B.
6J is immersed in the air cylinder 16
When the 06C operates, the rod 1606K protrudes until the regulating member 1606M contacts the lower guide 1606I against the urging force of the urging member 1606B.

Next, the operation and effect of the mixer valve having the above configuration will be described. FIG. 3A shows a state in which the air cylinder 1606C is not operated. At this time, since the first arm 1606D is urged downward by the urging force of the urging member 1606C, the stopper 1606A closes the liquid outlet 1602B. Therefore, the cement slurry stored in the second tank 1603 is not discharged.

FIG. 3B shows a state where the air cylinder 1606C is operating. At this time, since the first arm 1606D is moved upward by the driving force of the air cylinder 1606M, the stopper 1606A is pulled up to open the liquid outlet 1602B. Therefore, the cement slurry stored in the tank main body 1602A of the first tank passes through the liquid outlet 1602B and the lower second tank 1
It is discharged to 603.

When the mixer valve 1606 is in the closed state, as shown in FIG.
If the hand 606F is pulled upward by hand against the urging force of the urging member 1606B, the stopper 1606A also moves upward together with the first arm 1606D and the liquid outlet 1602
B is released.

The mixer valve (liquid valve) configured as described above has the following advantages. First, as a conventional liquid valve, there is an electromagnetic valve, an electric ball valve, or an air-driven ball valve. In the electromagnetic valve, dust contained in the liquid is clogged in a liquid flow path, or the electric ball valve, an air-driven ball valve is used. In the ball valve, similar dust often gets stuck in the ball portion, and it is necessary to perform sufficient cleaning, and the maintenance work is troublesome. On the other hand, the liquid valve according to the present embodiment is configured so that the liquid outlet is opened and closed by the stopper moving along the axis passing through the center of the liquid outlet. Is less likely to occur, less maintenance work such as cleaning is required, viscosity is increased, and opening and closing operation can be reliably performed even on solidified and adhered cement slurry. Second, if the supply of an electric signal or air for controlling the opening / closing operation of the solenoid valve, the electric ball valve, and the air-driven ball valve is stopped, the opening / closing operation cannot be performed. On the other hand, in the liquid valve according to the present embodiment, even when the supply and discharge of air to the air cylinder serving as the driving unit is stopped, the liquid discharge port is opened by pulling up the handle 1606F for the manual opening operation. There is an advantage that can be. Note that, of course, these effects are similarly exerted in the water discharge valve 1410.

Next, the configuration of the level switches 1604 and 1605 of the first tank and the second tank will be described with reference to FIG. Since the configuration of each level switch is the same,
A description will be given by taking the level switch 1604 as an example. The level switch 1604 is connected to the tank main body 1602 of the first tank 1602.
A is provided in A and constitutes a liquid level detector for detecting the level of the liquid level of the cement slurry that is flowing.

A stirring blade 1602D for stirring the cement slurry is provided at the bottom inside the tank body 1602A. The rotation of the stirring blade 1602D causes the cement slurry A to be stirred and flow in the direction of arrow D. It is supposed to be.

The level switch 1604 is connected to the base member 1
604A, holding member 1604B, limit switch 16
04C, a pendulum member 1604D, and the like. The base member 1604A is attached to the tank main body 1602A. The holding member 1 is attached to the base member 1604A.
604B is pivotally supported by pin 1604E. The pendulum member 1604D has a bar shape extending in the vertical direction, and is held by a holding member 1604B at a position displaced from the position of the pin 1604E. Therefore,
The pendulum member 1604D is configured to swing integrally with the holding member 1604B with the pin 1604E as a fulcrum. Here, the pendulum member 1604D is configured such that the lower end 1604F, which is a portion facing the cement slurry A, swings along the flow direction of the cement slurry A (the direction of arrow D).

The limit switch 1604C is connected to the main body 16
04G, a movable piece 1604H, and a biasing member (not shown) built in the main body 1604G. Movable piece 1604H
Is biased in a direction protruding from the main body 1604G by a biasing member, and is configured to output an open / close signal by performing an on / off operation by pushing the movable piece 1604H into the main body 1604G. The tip of the movable piece 1604H is connected to the upper end 1604I of the pendulum member 1604D so that the movable piece 1604H advances and retreats in response to the swing of the pendulum member 1604D so that the main body 1604G is turned on and off. It is configured.

As shown in FIG. 3B, the pendulum member 16
04D is located above the liquid surface T of the cement slurry A, that is, when the pendulum member 16
When no force due to the flow of the cement slurry A is acting on 04D, the pendulum member 1404D is moved in the vertical direction by a movable piece 1604H that is biased in a direction protruding from the main body 1604G by a biasing member of a limit switch 1604C. At a tilted position (first position). At this time, the limit switch 16
04C is, for example, ON corresponding to the position of the movable piece 1604H.
It has become.

As shown in FIG. 3A, the pendulum member 16
04D is located below the liquid level T of the cement slurry A, that is, when the pendulum member 16
When a force due to the flow of the cement slurry A is acting on 04D, the pendulum member 1404D is swung along the flow direction of the cement slurry A with the pin 1604E as a fulcrum, and the movable piece 1604H of the limit switch 1604C is moved.
Is positioned at a position (second position) where the is pushed into the main body 1604G. At this time, the limit switch 16
04C corresponds to the position of the movable piece 1604H, for example, OF
It is F.

Next, the function and effect of the liquid level detector 1604 will be described. As shown in FIG.
When the liquid level T of the cement slurry A stored in 602A is above the lower end 1604F of the pendulum member 1604D, the pendulum member 1604D is swung to the second position by the flow of the cement slurry A. Therefore, the limit switch 1604C is OFF. As shown in FIG. 3 (B), when the liquid surface T of the cement slurry A stored in the tank body 1602A is at a position below the lower end 1604F of the pendulum member 1604D, the pendulum member 1604D is limited. Switch 16
Since the lever is swayed to the first position by the action of the biasing member 04C, the limit switch 1604C is ON.

Therefore, the limit switch 1604C
The height of the liquid surface T of the cement slurry A stored in the tank body 1602A can be detected by the opening / closing signal output from. That is, the pendulum member 1604
By setting the position of the lower end 1404F of D to a detection position at which the height of the liquid level is to be detected, a limit switch 1604 determines whether or not the height of the liquid level falls below the detection position.
It can be detected by the open / close signal output from C. This open / close signal is input to the cement slurry control panel 2000 as a detection signal.

The level switch 1 of the second tank 1603
605 also has the same configuration as described above, and is configured to detect whether or not cement slurry is stored in the second tank 1603 by this level switch 1605. The detection signal of the level switch 1605 is also input to the cement slurry control panel 2000.

The level switch configured as described above detects the liquid level by swinging the pendulum member by the flowing liquid. Accordingly, it is preferable that the detection signal (open / close signal) of the level switch is made valid and invalid, respectively. For example, the opening and closing signal of the cement slurry may be made valid only during the period when the stirring device (stirring means) for stirring the cement slurry is operating.

As described above, the liquid level detector according to the present embodiment has the following effects. Conventionally, an electrode type water level gauge or a float type water level meter has been used as a liquid level height detector for detecting the liquid level. In addition, a detector that measures the distance to the liquid surface by applying ultrasonic waves or light to the liquid surface and detects the liquid surface height based on the measurement result is also used.
However, the electrode type water level meter has a drawback that the liquid to be detected is limited to a conductive type and cannot be used with a liquid to which dirt adheres to the electrode. In addition, the float type water level meter has a drawback that when the liquid is agitated and bubbles are generated, the float floats on the bubbles, so that the liquid level cannot be accurately detected. Further, a detector using ultrasonic waves or light has a disadvantage in that the cost is high, and detection becomes impossible if dirt adheres to a portion where ultrasonic waves or light passes.

On the other hand, the liquid level detector according to the present embodiment can be used regardless of the nature and type of the liquid as long as the liquid to be detected is flowing. Also, even if the liquid is agitated to form bubbles, the pendulum member 160
Since 4D is not affected by bubbles, the liquid level can be accurately detected. Further, since no ultrasonic wave or light is used, the influence of dirt is not expected, and the use of an inexpensive limit switch saves cost. Also,
The detection position of the liquid level can be set only by adjusting the position of the lower end 1604F of the pendulum member 1604D. Further, even if the pendulum member 1604D becomes dirty or damaged, the pendulum member 1604D can be easily replaced, and maintenance work is easy. That is, the liquid level detector of the present embodiment is suitable for detecting the liquid level of the cement slurry.

Next, the operation of the cement slurry producing apparatus of the present invention will be described with reference to the flowcharts of FIGS. First, the operation of the automatic driving preparation will be described with reference to FIG. By performing a predetermined operation on the hand control panel 2004 or the like, an instruction to start an operation for automatic operation preparation is given to the cement slurry control panel 2000 via the plant control panel 2002. First, the cement slurry control panel 2000 includes a first tank 1602 and a second tank 1603 of a mixer.
(S1).
Then, the first switch of the mixer is set by the level switch 1604.
The liquid level of the tank 1602 is detected (S2). If it is detected from the result of the level switch 1604 that the liquid level of the cement slurry in the first tank 1602 exceeds a predetermined height (“Y” in S2), the liquid of the cement slurry in the second tank 1603 is detected. Detect surface height (S1
0).

If "Y" in step S10, that is, if it is detected that the cement slurry is stored in the second tank 1603, the operation for automatic operation preparation is completed. When the automatic operation preparation is completed, the cement slurry control panel 2000
Sends a signal indicating completion of automatic operation preparation to the plant control panel 20.
The control signal is transmitted to the control panel 2004 via the control panel 02, and the control panel 2004 turns on the indicator lamp indicating the completion of the automatic operation preparation based on the signal.

On the other hand, in step S 2, “N”, that is, the first tank 160
When it is detected that the liquid level of the second cement slurry is below the predetermined height, the measurement of the cement by the cement supply unit 1200 and the measurement of the water by the water supply unit 1400 are started (S3).

That is, the cement slurry control panel 200
0 based on the instruction from 0
Controls the horizontal screw conveyor 1206 and the vertical screw conveyor 1208 to transfer the cement from the cement tank 1202 to the weighing hopper 1210. On this occasion,
Control is performed based on the detection signal from the cement measuring load cell 1212 so that a predetermined amount of cement is put into the measuring hopper 1210.

The cement slurry control panel 2000
Controls the water supply pump 1404 to transfer the water in the water tank 1402 to the metering water tank 1406. At this time, control is performed such that a predetermined amount of water is supplied to the measuring water tank 1406 based on a detection signal from the water measuring water level meter 1408.

When the measurement of the cement and water is completed in this way (S4), the water discharge valve 1
410 is opened (S5). After a lapse of a predetermined time, a cement discharge valve (referred to as a cement valve in FIGS. 5 and 6) 1214 of the measuring hopper 1210 is opened (S6). Next, the cement discharge valve 1214 is closed (S7),
Water discharge valve (indicated as a water valve in FIGS. 5 and 6) 14
10 is closed (S8). As a result, cement and water are charged into the first tank 1602.

Since the stirring operation of the first tank 1602 has been started in step S1, the cement and water charged in the first tank 1602 are stirred to form a cement slurry.
After a predetermined time required for stirring has elapsed, the first tank 1602,
The stirring operation of the stirring device of the second tank 1603 is stopped (S
9).

Next, it is detected whether or not the cement slurry is stored in the second tank 1603 (S10). If the cement slurry is stored in the second tank 1603,
(“Y” in S10), the preparation for automatic operation is completed. At this time, the cement slurry is stored in both the first tank 1602 and the second tank 1603.

If "N" in step S10, that is, if the cement slurry is not stored in the second tank 1603, the mixer valve 1606 is opened and the first tank 1602 is opened.
Is poured into the second tank 1603 (S1).
1). As a result, the second tank 1603 is filled with the cement slurry.

Then, simultaneously with step S11, the cement metering by the cement feeder 1200 and the water feeder 1
The measurement of water by 400 is started (S12). When the measurement of the cement and water is completed (S13), the mixer valve 1
606 is closed (S14), the process proceeds to step S5, and the processes of steps S6 to S9 are executed to produce a cement slurry in the first tank 1602. Here, since the cement slurry is already stored in the second tank 1603, step S10 becomes "Y", and the preparation for automatic operation is completed.

Next, the operation of the automatic operation will be described with reference to FIG. By performing a predetermined operation on the hand control panel 2004 or the like, an instruction to start an automatic operation is given to the cement slurry control panel 2000 via the plant control panel 2002. When the automatic operation is started, the cement slurry control panel 2000 determines whether or not the automatic operation preparation described above is completed (S20). If the determination result is "N", the automatic operation preparation described above is performed. Move to the operation of. If the result of the determination in step S20 is "Y", the stirrers of the first tank 1602 and the second tank 1603 constituting the mixer are each started to perform a stirring operation (S21).

Then, the liquid level of the second tank 1603 is detected by the level switch 1604, and it is determined whether the liquid level of the cement slurry in the second tank 1603 is higher than a predetermined level (S22). If step S22 is "Y", the cement slurry is stored in the second tank 1603, so S22 is repeated. Step S22 is "N"
Then, since the cement slurry is not stored in the second tank 1603, the mixer valve 1606 of the first tank 1602
And release the cement slurry from the first tank 1602 to the second tank.
It is put into the tank 1603 (S23).

Then, the cement supply unit 1200 and the water supply unit 1400 start the measurement of cement and water, respectively (S24). When the measurement of cement and water is completed (S2
5) The mixer valve 1606 of the first tank 1602 is closed (S26), and the water discharge valve 1410 is opened to discharge water to the first tank 1602.
The cement is put into the tank (S27), and the cement discharge valve 1214 is opened to put the cement 1410 into the first tank 1602 (S28).

Next, the cement discharge valve 1214 is closed (S29), and the water discharge valve 1410 is closed (S29).
30). Then, after the cement and water are stirred in the first tank 1602 for a predetermined time to form a cement slurry, the stirring operation is completed (S31). Then, the process shifts to step S22 to repeat the same operation as described above.

According to the above-described operation, the cement slurry is stored in the first tank 1602 and the second tank 1603,
When the amount of the cement slurry in the tank 1603 becomes equal to or less than a predetermined amount, the measurement of the cement and the water is started. After the cement slurry in the first tank 1602 is put into the second tank 1603, the measured cement and water are added to the first tank. 1602 to make a cement slurry. Therefore, the cement slurry can be continuously produced and supplied by the first tank and the second tank.

Further, cement is supplied to the cement supply section 1200.
, And water is measured by the water supply unit 1400,
Since the cement slurry is prepared by putting the measured cement and water into the first tank 1602, the cement slurry having a stable quality can be supplied while keeping the ratio of water to cement constant.

Further, the first tank 16 is
02 to the cement discharge valve 1214
Therefore, the transfer of the cement to the mixer is automated, and it is possible to achieve an unmanned operation in a work environment where dust easily occurs. From the measuring water tank 1406 to the first tank 16
Since the input of water to 02 is controlled by the water discharge valve 1410, the transfer of water to 1602 is automated. First
Since the transfer of the cement slurry from the tank 1602 to the second tank 1603 is controlled by the mixer valve 1606, the transfer of the cement slurry is automated.

[0066]

As is apparent from the above description, the cement slurry producing apparatus of the present invention includes a cement supply section, a water supply section, a mixer, and a control device. While measuring and storing the cement, it is configured to put a measured predetermined amount of cement into the mixer, and the water supply unit measures and stores a predetermined amount of water, and dispenses the measured predetermined amount of water. The mixer has a first tank, a second tank, and a liquid level detector, and the first tank has a predetermined amount charged from the cement supply unit. The cement and a predetermined amount of water supplied from the water supply unit are stirred to form and store a cement slurry, the second tank,
The cement slurry supplied from the first tank is stored and agitated, and the stored cement slurry is supplied to a supply destination. The liquid level detector detects the cement slurry in the second tank. The controller is configured to detect whether or not the position of the liquid level is equal to or lower than a predetermined position, and the control device is configured such that the liquid level height detector detects that the position of the liquid level of the cement slurry in the second tank is equal to or lower than a predetermined position. When it is detected that the cement slurry in the first tank is
Into the tank, and instruct the cement supply unit to measure a predetermined amount of cement, and instruct the water supply unit to measure a predetermined amount of water, and after the cement and water measurement is completed, And the predetermined amount of water is supplied from the water supply unit to the first tank.

Therefore, when the position of the liquid level of the cement slurry in the second tank falls below a predetermined position, the cement slurry in the first tank is poured into the second tank. Then, the cement supply unit is instructed to measure a predetermined amount of cement, and the water supply unit is instructed to measure a predetermined amount of water. After the measurement of the cement and the water is completed, a predetermined amount of the cement is supplied from the cement supply unit to the first tank, and a predetermined amount of the water is supplied to the first tank from the water supply unit. Therefore, it is possible to continuously produce and supply cement slurry in which the ratio of cement and water is kept constant in the first tank and the second tank.

The powder valve of the present invention is provided at a powder discharge port of a hopper for storing powder, and controls the discharge of the powder, and is connected to the powder discharge port. A rubber chute that forms a bent conduit, and the intermediate portion of the rubber chute is sandwiched from outside of the rubber chute to close the conduit, and the conduit is opened by releasing the clamping. And an opening / closing means. Therefore, in the powder valve of the present invention, since the pipeline formed by the rubber chute is opened and closed by the opening / closing means, even if dirt made of powder or the like adheres to the rubber chute, the dirt is also removed together with the powder. Since it is dropped, there is little possibility that the pipe line will be blocked by dirt attached to the rubber chute. Also, it is easy to increase the valve opening ratio by increasing the cross-sectional area of the pipe formed by the rubber chute, and to shorten the time required for discharging the powder by increasing the valve opening ratio. Becomes possible. In addition, only a rubber chute may be considered as a consumable, and there is an advantage that the cost required for the consumable can be reduced.

The liquid valve of the present invention is provided at a liquid discharge port of a liquid tank for storing liquid and controls the discharge of the liquid. The liquid valve includes a stopper, an urging member, and a driving means. The stopper is disposed movably along an axis passing through the center of the liquid outlet between a closed position for closing the liquid outlet and an open position for opening the liquid outlet inside the liquid tank, The biasing member is configured to bias the stopper toward the closed position, and the driving unit is configured to move the stopper to the open position when activated. Therefore, according to the liquid valve of the present invention, the stopper moves along the axis passing through the center of the liquid outlet between the closed position that closes the liquid outlet and the open position that opens the liquid outlet inside the liquid tank. This opens and closes the liquid outlet. Therefore, compared to the conventionally used solenoid valves, electric ball valves, and air-driven ball valves, there is less risk of dust clogging the liquid flow path and getting stuck in the ball portion, and maintenance work such as cleaning can be performed. Less is needed.

Further, the liquid level detector of the present invention is a liquid level detector for detecting the liquid level of a flowing liquid, comprising a pendulum member and a limit switch. The pendulum member is supported above the liquid surface so that a portion facing the liquid surface of the liquid is swingable along a flow direction of the liquid, and a portion facing the liquid surface of the liquid is the liquid. The limit switch is located at the first position when not immersed in the liquid, and is swung to the second position by the flow of the liquid when the portion facing the liquid surface of the liquid is immersed in the liquid; Means that the pendulum member is the first
It is configured to output an open / close signal in conjunction with swinging between the position and the second position. Therefore, in the liquid level height detector of the present invention, the pendulum member is swung from the first position to the second position by the flowing liquid to output an open / close signal, so that the liquid to be detected flows. If used, it can be used regardless of the nature and type of the liquid. Further, even if the liquid is agitated and bubbles are generated, the pendulum member is not affected by the bubbles, so that the liquid level can be accurately detected. Further, since no ultrasonic wave or light is used, the influence of dirt is not expected, and the use of an inexpensive limit switch saves cost. Further, the detection position of the liquid level can be set only by adjusting the position of the pendulum member.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a cement slurry producing apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing a configuration of a parking lot shown in FIG.

FIG. 3 is an explanatory view showing a configuration of a powder valve, and FIG.
2A shows a valve closed state, and FIG. 2B shows a valve open state.

FIG. 4 is an explanatory view showing a configuration of a liquid valve, and FIG.
3A shows a valve closed state, and FIG. 3B shows a valve open state.

FIG. 5 is an operation flowchart illustrating an automatic operation preparation operation of the cement slurry manufacturing apparatus.

FIG. 6 is an operation flowchart illustrating an automatic operation operation of the cement slurry manufacturing apparatus.

[Explanation of symbols]

1000 Cement slurry production apparatus 1210 Measuring hopper 1210A Powder discharge port 1214 Cement discharge valve (powder valve) 1214A Rubber chute 1214B Opening / closing means 1406 Measuring water tank 1410 Water discharge valve (liquid valve) 1602 First tank 1603 Second tank 1604, 1605 Level switch (liquid level detector) 1604C Limit switch 1604D Pendulum member 1606 Mixer valve (liquid valve) 1606A Plug part 1606B Biasing member 1606C Air cylinder (drive means) 2000 Cement slurry control panel (control device)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Ryoji Yoshitake 4-6-15 Sendagaya, Shibuya-ku, Tokyo Inside Fujita Co., Ltd. (72) Hideo Tanijiri 4-6-115 Sendagaya, Shibuya-ku, Tokyo Stock Company Fujita Co., Ltd. (72) Inventor Yukihiro Watanabe 4-6-115 Sendagaya, Shibuya-ku, Tokyo Co., Ltd.Fujita Co., Ltd. 72) Inventor Osamu Tanaka 2-5-5 Tsurumi-Chuo, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Within Asuku Techno Construction Co., Ltd. (72) Inventor Takashi Miyai 2-6-1, Ginza, Chuo-ku, Tokyo Nikki Plantech Co., Ltd. F-term (reference) 4G056 AA 07 CB02 CB13 CB17 CC37 CC39 CD31 DA01 DA05 DA08

Claims (11)

[Claims] 1. A cement supply unit, a water supply unit, a mixer, and a control device, wherein the cement supply unit measures and stores a predetermined amount of cement, and transfers the measured predetermined amount of cement to the mixer. The water supply unit is configured to measure and store a predetermined amount of water, and to charge the measured predetermined amount of water to the mixer. The mixer includes a first tank and , A second tank, and a liquid level detector, wherein the first tank stores a predetermined amount of cement supplied from the cement supply unit and a predetermined amount of water supplied from the water supply unit. The second tank is configured to store and stir the cement slurry input from the first tank while stirring to form and store the cement slurry, and to supply the stored cement slurry to a supply destination. Composed of the above The liquid level height detector is configured to detect whether or not the position of the liquid level of the cement slurry in the second tank is equal to or less than a predetermined position, and the control device is configured such that the liquid level height detector is When detecting that the level of the liquid level of the cement slurry in the second tank is equal to or less than a predetermined position, the cement slurry in the first tank is charged into the second tank, and a predetermined amount of the cement slurry is supplied to the cement supply unit. While instructing the measurement of cement, instructing the water supply unit to measure a predetermined amount of water, and after the cement and water measurement is completed, the predetermined amount of cement is transferred from the cement supply unit to the first tank. The cement slurry producing apparatus is configured to be supplied and to supply the predetermined amount of water from the water supply unit to the first tank. 2. The cement slurry producing apparatus according to claim 1, wherein the cement slurry is a refractory coating spraying material used in construction work. 3. A rubber chute provided at a powder discharge port of a hopper for storing powder and controlling discharge of the powder, wherein a rubber chute forming a pipe connected to the powder discharge port is provided. An opening / closing means configured to close the pipeline by sandwiching an intermediate portion of the rubber chute from outside of the rubber chute, and to open the pipeline by releasing the sandwiching. Features powder valve. 4. The opening / closing means includes a first arm, a second arm, a link mechanism, and a driving means. One end of each of the first arm and the second arm is pivotally supported by a body of the hopper. The other end has a pressing portion for pressing a rubber chute, the pressing portion is disposed at a position sandwiching the rubber chute, and the link mechanism connects the first arm and the second arm to connect each other. It is configured to open and close the pressing portion,
The driving unit is configured to open and close the pressing unit by applying a driving force to the first arm and the second arm, and the closing of the conduit by the opening and closing unit is performed by closing the pressing unit. The powder valve according to claim 3, wherein the opening of the conduit by the opening / closing means is performed by opening the pressing portion. 5. A liquid valve provided at a liquid discharge port of a liquid tank for storing liquid and controlling discharge of the liquid, comprising: a plug portion, an urging member, and a driving unit, wherein the plug portion is Inside the liquid tank, the liquid discharging port is disposed so as to be movable along an axis passing through the center of the liquid discharging port between a closed position for closing the liquid discharging port and an open position for opening the liquid discharging port. A liquid valve configured to urge the plug toward the closed position, and wherein the driving means is configured to move the plug to the open position when activated. 6. A manually-opening handle is connected to the stopper, and the stopper is moved from the closed position by moving the manually-opening handle against the urging force of the urging member. The liquid valve according to claim 5, wherein the liquid valve is configured to move to the open position. 7. The liquid valve according to claim 5, wherein the driving unit is an air cylinder. 8. A liquid level detector for detecting a liquid level of a flowing liquid, comprising: a pendulum member; and a limit switch, wherein the pendulum member is provided above the liquid surface. A portion facing the liquid surface of the liquid is supported so as to be swingable along a flow direction of the liquid, and the portion facing the liquid surface of the liquid is located at the first position in a state where it is not immersed in the liquid. And
When a portion of the liquid facing the liquid surface is immersed in the liquid, the liquid is swung to a second position by the flow of the liquid, and the limit switch is configured such that the pendulum member is in a first position and a second position. The liquid level detector is configured to output an opening / closing signal in conjunction with the swinging motion. 9. The limit switch includes a main body, a movable piece that advances and retreats from the main body, and an urging member, wherein the movable piece is urged in a predetermined direction by the urging member,
The movable piece is configured to be turned on and off by being moved forward and backward, the movable piece and the pendulum member are connected, and the pendulum member is located at the first position by the urging force of the urging member. 9. The liquid level detector according to claim 8, wherein the liquid level detector is configured as follows. 10. The liquid level detector according to claim 8, wherein the first position is a position at which the pendulum member is positioned by an urging force of an urging member built in the limit switch. . 11. A stirrer for flowing the liquid is provided, and the opening / closing signal is made valid only during a period in which the stirrer performs a stirring operation. The liquid level detector according to 8, 9 or 10.