JP2932279B2 - Filtration device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for filtering liquid such as a cutting liquid used in a processing machine and a cleaning liquid used in a cleaning machine.

(Prior Art) Generally, as a first method of a liquid filtering device used in a processing machine or a washing machine, a liquid is sucked up from a dirty tank into which a suspension from the machine flows by a filtration pump. After once storing the filtered liquid in a clean tank once with a filter interposed in the middle of the discharge pipe of the filtration pump, the liquid is drawn up from the clean tank with a supply pump and supplied to a machine or the like. Are known.

Further, as another second method, filtration is performed in the middle of sucking up liquid by a supply pump through a suction filter that opens a suction port in a dirty tank, and the discharge liquid of the supply pump is directly supplied to the machine. Devices are known.

(Problems to be Solved by the Invention) However, the first method conventionally known requires two tanks, a dirty tank and a clean tank, and also requires a filtration pump and a supply pump. However, there is a disadvantage that the installation area of the filtration device becomes large and the equipment cost becomes expensive.

Also, in the second method conventionally known, a pump dedicated to filtration is not required, but in terms of installation area, generally, the height of outflow of liquid from the machine is about 400 mm from the floor surface, The liquid level in the dirty tank will of course not exceed this level. By the way, if air is sucked in during operation of the pump, the pump may not be able to operate. As a method of preventing the inhalation of air, it is sufficient to take a sufficient amount of liquid in the dirty tank.
However, since the liquid level of the dirty tank is restricted by the height of the outflow from the machine for the above-mentioned reason, the planar area of the dirty tank is widened to secure the liquid amount, and therefore, a pump dedicated to filtration is used. However, there is a drawback that the installation area becomes large even if is unnecessary.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide a low-cost, easy-to-use filtration device which does not require a pump dedicated to filtration, and has a small installation area.

(Means for Solving the Problems) For this reason, the present invention has a dirty tank into which a suspension flows in and a sludge discharge mechanism, a suction port opened in the dirty tank, and a backwashing mechanism for a filtration element. The other of the suction filter, the suction filter outlet pipe, the pump suction pipe, and the other of the air pipe having means for opening one of the dirty tanks at a predetermined liquid level and preventing sludge or the like from passing therethrough, and an on-off valve A liquid supply pipe for supplying the liquid through the like is opened, a liquid tank made airtight except for these openings, a liquid level detecting means of the liquid tank, and when necessary,
A liquid flow path switching valve mechanism for closing an opening of the pump suction pipe and the suction filter outlet pipe to the liquid tank, and instead communicating with the pump suction pipe and the suction filter outlet pipe.

(Operation) According to the above configuration, since the filtration is performed by the suction filter while the pump is sucking the liquid, the discharge liquid of the pump can be directly supplied to the washing machine and the processing machine, and another pump dedicated to filtration is not required. . In addition, since the liquid tank is attached to the pipeline between the suction filter and the pump, the liquid tank can be attached three-dimensionally to an upper part of a dirty tank or the like as long as the height is less than the height at which the pump can suck. Regarding the shape of the liquid tank, there is no restriction on the height of the liquid flowing out of the machine, and the height dimension can be sufficiently obtained.
Even if the planar area is reduced, the tank volume can be secured,
The amount of liquid stored is sufficient. Therefore, the pump having the suction pipe opened in the liquid tank rarely sucks air during operation. After the operation of the pump is started, the liquid in the dirty tank is first sucked until the liquid level in the dirty tank becomes lower than the lower end of the air pipe. Since the suction and discharge liquid volumes of the pump are equal, an empty volume for the inflow of the liquid flowing back from the machine is always ensured in the dirty tank,
Therefore, the volume of the dirty tank does not need to be increased more than necessary. Therefore, in addition to the fact that the liquid tank can be installed three-dimensionally, the installation area of the filtration device can be greatly reduced. Further, the liquid supply to the liquid tank can be performed while the operation of the filtration device is continued by switching the liquid flow path switching valve mechanism at the time of liquid supply.

(Example) Hereinafter, an example of the present invention is described based on a drawing.
In FIG. 2, 1 is a dirty tank and a cylindrical side wall 2;
It has a flat bottom surface 3. Liquid from the machine flows through the liquid chute 4 into the dirty tank. Reference numeral 5 denotes a liquid tank, which is erected above the dirty tank via a bracket 6. The liquid tank has a volume for storing most of the liquid used in the filtration device, and is made airtight except for openings such as a liquid inflow port and an air inflow port into the liquid tank. 7, a suction filter; and 8, a filter case constituting the suction filter. The filter case has a cylindrical shape slightly smaller than the side wall 2 of the dirty tank, and the bracket 9 is concentric with the dirty tank and the lower part of the filter case is positioned slightly above the bottom surface 3 of the dirty tank. And is fixed to the side wall 2. In addition, a filter element 10 is soaked over the entire lower surface of the filter case, and the suction filter is opened to the bottom of the dirty tank via the filter element. In addition, a filter cover 11 is attached to the upper end surface of the filter case, so that a filter chamber 12 is formed by the filter case, the filtering element, and the filter cover. Reference numeral 13 denotes a rotating shaft provided perpendicularly to the center of the suction filter. Above the rotating shaft, the bracket 6 is mounted on the bracket 6 and the center of a support 14 having both ends attached thereto (FIG. 3). It is rotatably supported at 16.

A sprocket 17 is key-fitted to the uppermost part of the rotating shaft. Reference numeral 18 denotes a water joint disposed above the filter lid 11, and a water passage 19 is provided therein. A branch pipe 21 of a discharge pipe of a supply pump 20 shown in FIG. ing. The upper and lower holes of the water joint are O-rings.
It is sealed at 22, 23 and penetrates. Reference numeral 24 denotes a water passage provided inside the rotary shaft in the axial direction thereof, and an upper portion thereof communicates with the water passage 19. 25 is a component of the sludge discharge mechanism, is an upper rotary shaking plate, the rotary shaft is fitted into a fitting hole provided at one end thereof, the rotary shaft and the upper rotary shaking plate by the key 26, They rotate together.
In addition, the rotation shaft is further provided with an O-ring
Sealed at 150 and penetrating into the filter chamber. The other end of the upper rotary shaving plate extends slightly outward from the outer periphery of the filter lid, and the lower surface 27 is in contact with the upper surface of the filter lid 11.

Also, as shown in FIG.
Is a distance A from the radius line 29 extending from the rotation center of the rotation shaft on the rotation direction side of the rotation shaft.
The filter lid is moved from the center to the outer peripheral direction.

In FIG. 2, reference numeral 30 denotes a backwash pipe provided in the filter chamber 12, which is a component of a backwash mechanism of a filtration element. The rotating shaft is fitted into a fitting hole provided at one end of the backwash pipe, and the rotary shaft and the backwash pipe are integrally rotated by the key 31. The other end of the backwash pipe extends radially through the filter chamber and reaches near the inner periphery of the filter chamber. A hollow water passage 32 is provided substantially throughout the inside of the backwash pipe, and one end of the water passage 32 communicates with a lower portion of a water passage 24 provided inside the rotary shaft. Reference numeral 33 denotes a plurality of nozzle holes provided at intervals over substantially the entire length of the backwash pipe, and one end thereof communicates with the water passage 32 and opens at a right angle to the filtration surface of the filtration element 10. The rotating shaft further penetrates a hole provided in a boss 34 at the center of the filtration element by being sealed with an O-ring 35, and the lower rotating shaft is a lower rotating shaving plate at the bottom of the dirty tank.
The rotary shaft and the lower rotary shaving plate are fitted into a fitting hole provided at one end of 36, and can be integrally rotated by the key 37 between the lower surface of the suction filter and the bottom surface 3 of the dirty tank. I have. Further, the other end of the lower rotary shaving plate extends in the radial direction of the dirty tank, reaches near the inner periphery of the side wall 2, and has a lower end surface in contact with the bottom surface 3 of the dirty tank.

As shown in FIG. 5, when viewed from a plane, the leading edge 38 of the lower rotary shaving plate has a radius line 39 extending from the center of rotation of the rotary shaft.
From the rotation direction of the rotation axis by the distance A from
By rotating the lower rotary shaking plate, the sludge settled on the bottom surface 3 of the dirty tank is moved outward from the center.

In FIG. 3, reference numeral 40 denotes a liquid flow path switching valve mechanism provided below the liquid tank 5. Reference numerals 41 and 42 denote three-way switching valves, and a connection port 43 of the three-way switching valve 41 and a connection port 44 of the three-way switching valve 42 communicate with each other via a pipe 45. Further, the connection port 46 of the three-way switching valve 41 and the connection port 47 of the three-way switching valve 42 are respectively opened inside from the lower wall of the liquid tank. 3 more
The connection port 48 of the one-way switching valve 41 communicates with one end of a suction filter outlet pipe 49. The other end of the suction filter outlet pipe opens from the side surface of the filter case 8 into the filter chamber 12. Reference numeral 50 denotes a check valve interposed in the middle of the suction filter outlet pipe. The check valve opens for the flow of liquid in the suction direction of the supply pump 20, and the liquid stops flowing when the pump stops. If it tries to flow backward in the suction direction, it will close. The connection port 51 of the three-way switching valve 42 communicates with the supply pump suction pipe 52.
Reference numerals 53 and 54 denote switching levers for switching the liquid flow paths inside the three-way switching valves 41 and 42.
They are rotatably connected by 56 and 57. More pins
56 has a piston rod tip 59 of an air cylinder 58
Are rotatably connected, and a rear portion of the air cylinder 58 is provided with a mounting plate 60 mounted at a lower portion of the liquid tank 5.
Are rotatably connected by a pin 61. Further, air piping 62, 63 connected to both ends of the air cylinder is connected to a compression air source 65 via a two-position switching type electromagnetic switching valve 64. At the forward end of the air cylinder, the liquid flow path inside the three-way switching valve 41 communicates from the connection port 48 to the connection port 46, and the liquid flow path inside the three-way switching valve 42 connects to the connection port 51 and the connection port. 47 are configured to communicate with each other. Therefore, the forward end m of the air cylinder
Then, the suction filter outlet pipe and the supply pump suction pipe open to the liquid tank via the three-way switching valves 41 and 42. Also, at the retreat end n of the air cylinder, the connection port 48 and the connection port 43 communicate with the liquid flow path inside the three-way switching valve 41,
The liquid flow path inside the one-way switching valve 42 is configured such that the connection port 44 and the connection port 51 communicate with each other. At this time, the suction filter outlet pipe and the supply pump suction pipe are both connected to the liquid tank. Is closed, and the three-way switching valve 41 and the pipe 45 and the three-way switching valve 42 communicate with each other.

In FIG. 2, reference numeral 70 denotes a sludge conveyor which is also a component of the sludge discharging mechanism. A rectangular tube 71 having a rectangular cross section is vertically fixed to the side wall 2 of the dirty tank via a mounting plate 72, and the bottom of the dirty tank and the bottom of the square tube are
They are connected by a communication hole 73. At the top of the square tube, a shaft 74
Is rotatably supported by bearings 76 and 77 attached to the outer wall of the rectangular cylinder, and a shaft 75 is rotatably supported by bearings 78 and 79 attached to the outer wall of the rectangular cylinder at the lower part. . A sprocket 80 is key-fitted to the shaft 74, and a sprocket 81 is key-fitted to the shaft 75. The sprocket 80 and the sprocket 81 are connected by a chain 82, and a mounting bracket 83 of the chain 82 includes:
Raised plate whose width is almost the same as the inner width B of the rectangular cylinder
84, an appropriate number are attached.

As shown in FIG. 6, the bottom surface 85 of the square cylinder is defined by a distance C between the axis of the shaft 75 and the inner surface 86 of the side wall of the square tube as a radius.
The tip 87 of the lifting plate moves while contacting the bottom surface 85 and the inner wall surface 86 of the rectangular cylinder when the chain 82 rotates. Reference numeral 88 denotes a sludge discharge port opened at the upper part of the rectangular cylinder, and one end of a sludge chute 89 is attached to an outer wall of the rectangular cylinder slightly below the sludge discharge port. Numeral 90 denotes a scraping plate, one end of which is attached to the side wall of the sludge chute by a shaft 91 so as to be swingable up and down. The other end of the scraping plate 90 is bent substantially at a right angle and has the same width as the scraping plate. At the lower side p of the scraping plate swinging, the lower end portion 92 comes into contact with the upper flat portion 93 near the mounting bracket 83 of the scraping plate 84, which has risen with the rotation of the chain, and the scraping plate is further raised by further raising the scraping plate. Is swung upward about the shaft 91. Therefore, the lower end portion 92 moves toward the sludge discharge port while being in contact with the upper flat portion of the scraping plate, and at the swing upper end q, finally comes off the upper flat portion and drops to the swing lower end by its own weight. . The scraping plate repeats this upward and downward swinging motion each time the scraping plate rises.

In FIG. 2, reference numeral 95 denotes a drive motor for driving a sludge discharge mechanism and a backwashing mechanism for a filtration element. A flange portion 96 is fixed to an upper portion of the rectangular tube 71, and a sprocket 98 is key-fitted to the motor shaft 97. ing. 99 is a conduction shaft, and bearings are provided on support brackets 100 and 101 attached to the outer wall of the rectangular cylinder.
At 102 and 103, they are rotatably supported in parallel with the rectangular tube. A sprocket 104 is key-fitted on the upper part of the conduction shaft 99,
Sprocket 104 and sprocket by chain 105
98 is connected. A bevel gear 106 is key-fitted to an intermediate portion of the conduction shaft 99, and a bevel gear 107 key-fitted to one end of the shaft 74 attached to the upper part of the rectangular tube.
And are engaged. Further, a sprocket 108 is key-fitted to the lower portion of the transmission shaft 99, and is connected to the rotating shaft 13 by a key-fitted proket 17 and a chain 109. 110 is an air tube. The air pipe penetrates the lower wall of the liquid tank 5, and its upper end is opened at the upper part in the liquid tank. It goes without saying that the air pipe penetration portion on the lower wall of the liquid tank is kept airtight. The lower portion of the air pipe has a stepped inner hole. The large-diameter portion 114 rises when the level of the dirty tank rises, and closes the small-diameter portion 115. A ball-shaped check valve 116 is provided. At the lower end surface of the air pipe, a filtration membrane 117 having substantially the same filtration accuracy as the filtration element 10 is attached, and the air pipe is opened above the suction filter of the dirty tank via the filtration membrane. Reference numeral 120 denotes an upper limit detector for detecting the upper limit liquid level of the liquid tank, and reference numeral 121 denotes a lower limit detector for detecting the lower limit liquid level. The upper limit detector 120 and the lower limit detector 121 are provided with O
The outer peripheral portions thereof are sealed by rings 122 and 123, and the tip detecting sections 124 and 125 are attached in a state of being inserted into the liquid tank, respectively. The upper and lower detectors detect the liquid level in the liquid tank using the capacitance difference between the liquid and air, and are sent when the tip detectors 124 and 125 are in contact with the liquid. The signal turns on, and the signal turns off when it comes into contact with air. Reference numeral 126 denotes a liquid supply pipe. One end of the liquid supply pipe is opened on the side wall of the liquid tank, and an electromagnetic on-off valve 127 is provided on the way. The other end of the liquid supply pipe is connected to a discharge port of a liquid supply pump 129 which opens a suction port into the supply liquid tank 128.

With the above configuration, in the present invention, prior to the start of the operation of the filtration device, the supply pump 20 is filled with priming water, the liquid tank 5 is replenished with a sufficient liquid up to near the upper limit, and the dirty tank 1 is also supplied with an air pipe. When the electromagnetic switching valve 64 is excited while the liquid is being replenished to slightly above the lower end of the air cylinder 58, the air cylinder 58 moves forward, and at the forward end m, the three-way switching valve 41 moves from the connection port 48 to the connection port 46. The internal liquid flow path communicates with the three-way switching valve 42, and the internal liquid flow path communicates from the connection port 51 to the connection port 47. As a result, the suction filter outlet pipe 49 and the supply pump suction pipe 52 Open to liquid tank. When the supply pump 20 is started in this state, the liquid in the liquid tank is sucked into the supply pump, discharged, and supplied to the machine. When the liquid in the liquid tank is sucked into the supply pump, the inside of the liquid tank becomes a negative pressure.
The liquid is sucked into the liquid tank via the suction filter 7 and is filtered when passing through the filter element 10. At this time, a small amount of liquid is about to be sucked up from the air pipe 110, but the check valve 116 rises and the small-diameter portion 115
, The suction of liquid from the air tube is prevented. The filtration membrane 117 also prevents sludge from entering the air tube. When the operation of the supply pump 20 continues and the liquid level of the dirty tank drops and becomes lower than the lower end of the air pipe,
Since the check valve 116 is lowered and the small diameter portion 115 is opened, the air passing through the filtration membrane 117 enters the liquid tank through the air pipe. Therefore, the suction of the liquid from the dirty tank via the suction filter is stopped, and only the liquid in the liquid tank is sucked into the supply pump and discharged.
After a short time, the liquid supplied to the machine by the supply pump flows back through the liquid chute 4 to the dirty tank. This strange, when the liquid level of the dirty tank rises and becomes more than the lower end of the air pipe,
The flow of air from the air pipe into the liquid tank stops, and the liquid is sucked up again while being filtered through the suction filter until the liquid level in the dirty tank reaches the level at the lower end of the air pipe. Therefore, the filtration device is usually operated with the liquid almost below the level at the lower end of the air pipe always remaining in the dirty tank. If the operation of the filtration device is interrupted and the operation of the supply pump is also stopped, the liquid remaining in the machine will return to the dirty tank for a while after the discharge of the liquid is finished,
As a result, the liquid level in the dirty tank rises above the lower end of the air pipe and stops. Since some of the liquid adheres to the work that has been evaporated or processed by the machine and is carried away, if the amount of liquid flowing back to the dirty tank decreases, the liquid level of the dirty tank falls below the lower end of the air pipe. The liquid of this reduced amount enters air into the liquid tank from the air pipe, and the liquid in the liquid tank is discharged by the supply pump, and is automatically replenished to the dirty tank. Therefore, the liquid level of the liquid tank gradually decreases as the operation of the filtration device continues. As a result, the liquid level in the liquid tank is
When it becomes 1 or less, the signal from the lower limit detector changes from ON to OFF. The change of this signal demagnetizes the electromagnetic switching valve 64, retracts the air cylinder to the retreat end n, switches the liquid flow path inside the three-way switching valves 41 and 42, and sucks the suction filter outlet pipe 49 and the supply pump. The opening of the pipe 52 to the liquid tank is closed, and the suction filter outlet pipe and the supply pump suction pipe are communicated via the three-way switching valve 41, the pipe 45, and the three-way switching valve 42. In this state, when the electromagnetic on-off valve 127 is excited and opened to start the liquid supply pump 129, liquid supply to the liquid tank is started. At this time, the air in the liquid tank is discharged outside through an air pipe.
In addition, the supply pump can suck up the liquid remaining in the dirty tank through the suction filter and continue to supply the liquid to the machine. You can continue driving without doing it. When the liquid level in the liquid tank reaches the upper limit detector 120 due to the liquid supply, the signal of the upper limit detector turns ON. When the electromagnetic on-off valve 127 is closed by this ON signal and the liquid supply pump 129 is stopped, the liquid supply to the liquid tank is completed. Next, the electromagnetic switching valve 64
Is re-excited, the air cylinder is advanced, the suction filter outlet pipe and the supply pump suction pipe are reopened to the liquid tank respectively, and the operation returns to normal operation. When the operation of the filtration device is stopped for a long period of time, the electromagnetic switching valve 64 is demagnetized and the air cylinder is retracted to the retracted end, thereby connecting the suction filter outlet pipe and the supply pump suction pipe, By closing the opening to the liquid tank, it is possible to reliably prevent the liquid in the liquid tank from flowing out when the operation is stopped for a long time. The check valve 50 also prevents the liquid in the outlet pipe of the suction filter from flowing back in the anti-suction direction when the supply pump is stopped. While the supply pump is operated, the drive motor 95 is also operated at the same time. The rotational force of the drive motor is sprocket 98,
It is transmitted to the transmission shaft 99 by the chain 104 and the chain 105. Due to the rotation of the conduction shaft, the bevel gear 106 key-fitted to the intermediate portion of the conduction shaft, the bevel gear 107 meshing with the bevel gear 106, and the shaft 74 in which the bevel gear 107 is key-fitted rotate sequentially. The rotation of the shaft 74 also rotates the sprocket 80 keyed to the shaft 74. As the sprocket 80 rotates, the chain 82 and the sprocket 81 also rotate sequentially. Further, the rotation of the transmission shaft 99 is transmitted to the sprocket 108, the chain 109, and the sprocket 17 key-fitted to the lower portion of the transmission shaft, and the sprocket 17 rotates the rotation shaft 13 key-fitted. .
By rotating the rotating shaft, fitted to the rotating shaft,
Upper rotary shaving board 25, backwash pipe 30, and lower rotary shaking board
36 rotates at the same time. Part of the liquid discharged from the supply pump 20
Through the branch pipe 21, the water enters the water passage 19 provided inside the water joint 18, and further, the water passage provided inside the rotary shaft.
After passing through 24, it enters the water passage 32 in the backwash pipe, and the nozzle hole 33
From the filter element 10 to the filtration surface. Since the backwash pipe is rotated by the rotating shaft, the entire surface of the filter element is continuously backwashed, and the sludge attached to the filter element is dropped on the bottom of the dirty tank. In addition, the sludge flowing into the dirty tank mixed with the liquid refluxing from the machine also sinks on the upper surface of the filter lid 11 of the suction filter, but rotates with the rotating shaft.
By 25, the filter lid is moved from the center of the filter lid toward the outer periphery, and also falls to the bottom of the dirty tank. The sludge that has fallen to the bottom of the dirty tank is moved in the outer circumferential direction of the bottom of the dirty tank by the lower rotary shaking plate 36 that rotates together with the rotating shaft. And enters the lower part of the square tube 71. The sludge that has entered the lower part of the rectangular tube is flat on the upper surface of the scraping plate 84 attached to the rotating chain 82.
It is placed on 93 and moved upward along the inner wall of the rectangular cylinder, and when it reaches the upper part of the sludge discharge port 88 provided at the upper part of the rectangular cylinder, the scraper plate 90 flats the upper surface of the scraper plate. The portion is moved in the direction of the sludge discharge port, falls on the sludge chute 89 at the swinging upper end q of the scraping plate, falls along the sludge chute, and is discharged to the outside.

(Effects of the Invention) According to the above configuration, the supply pump performs filtration with the suction filter interposed in the middle of the supply pump suction pipe while sucking the liquid from the dirty tank.
The liquid discharged from the supply pump can be directly supplied to a washing machine or a processing machine, and a special pump for filtration is not required, so that inexpensive equipment can be provided. Also, the liquid tank that stores most of the liquid used in the filtration device is installed between the suction filter and the supply pump. Can be attached three-dimensionally. The shape of the liquid tank is not restricted by the height of the liquid flowing out of the machine. The quantity is enough. Therefore, the supply pump having the suction pipe opened in the liquid tank does not suck air during operation. Further, after the operation of the supply pump is started, the liquid in the dirty tank is first sucked until the liquid level in the dirty tank falls below the lower end of the air pipe. Since the suction amount and the discharge amount of the liquid from the supply pump are equal, an empty volume for the inflow of the liquid refluxed from the machine is always ensured in the dirty tank. For this reason, the volume of the dirty tank can be minimized. Therefore, in addition to the fact that the liquid tank can be installed three-dimensionally, the installation area of the filtration device can be greatly reduced. Also, clogging of the filtration element is continuously backwashed, and sludge is automatically discharged. Furthermore, the supply of the liquid to the liquid tank can be performed while the operation of the filtration device is continued, which is a revolutionary filtration device that is very easy to use.

[Brief description of the drawings]

The drawings each explain a filtration device according to the present invention. FIG. 1 is a plan view, and FIG. 2 is a sectional view taken along a line aa of FIG. 3 is a side view, FIG. 4 is a cross-sectional view taken along line bb of FIG. 2, and FIG. 5 is a cross-sectional view taken along line cc of FIG. . FIG. 6 is a sectional view taken along line dd of FIG. 2 and shows a section of the sludge conveyor. 1 ... Dirty tank, 5 ... Liquid tank, 7 ... Suction filter, 10 ... Filtration element, 13 ... Rotating shaft, 20 ... Supply pump, 25 ... Upper rotating shaving board, 30 ... Backwash pipe , 36 …… Lower rotating shaving board, 40 ……
Liquid flow switching valve mechanism, 70 …… Sludge conveyor, 95 ……
Drive motor, 110: air tube, 120: upper limit detector, 12
1 ... Lower detector, 126 ... Supply pipe.

Claims (1)

(57) [Claims] 1. A filtration device for filtering a liquid, a dirty tank having a sludge discharge mechanism, a suction filter having a suction port opened in the dirty tank and having a backwashing mechanism for a filtration element, and a suction filter outlet. The other of the pipe, the pump suction pipe, and the other of the air pipe which has a means for opening one to a predetermined liquid level of the dirty tank and preventing sludge from passing therethrough, and the liquid supply pipe for supplying the liquid when necessary. Then, except for these openings, the liquid tank is made airtight, means for detecting the liquid level in the liquid tank, and the pump suction pipe and the suction filter outlet pipe opening to the liquid tank are closed when necessary. A liquid flow path switching valve mechanism that connects the pump suction pipe and the suction filter outlet pipe,
A filtering device, comprising: