CN113350884B

CN113350884B - Secondary precision filter

Info

Publication number: CN113350884B
Application number: CN202110625270.1A
Authority: CN
Inventors: 杨宏良; 王怀平
Original assignee: Zhejiang Sipu Intelligent Technology Co ltd
Current assignee: Zhejiang Sipu Intelligent Technology Co ltd
Priority date: 2021-06-04
Filing date: 2021-06-04
Publication date: 2022-04-15
Anticipated expiration: 2041-06-04
Also published as: CN113350884A

Abstract

The invention discloses a secondary precision filter, which comprises a sand cylinder, filter sand, a filter assembly and a control valve, wherein the filter sand is contained in the sand cylinder, the filter assembly comprises a filter piece, a water collecting pipe, a fine filter cylinder and a water outlet pipe, a plurality of filter pieces are distributed at one end of the water collecting pipe, a mounting port is formed in the side surface of the sand cylinder, the cylinder port end of the fine filter cylinder is fixed on the mounting port, a cylinder cover is connected to the mounting port in a sealing mode, two pipe interfaces are arranged on the fine filter cylinder and are respectively connected with the water collecting pipe and the water outlet pipe, a filter element is arranged in the fine filter cylinder, a connecting disc is arranged at the bottom of the control valve, a filter water inlet and a filter water outlet are further formed in the control valve, the water outlet pipe is communicated with the filter water outlet, and the filter water inlet is communicated with an inner cavity of the sand cylinder. The secondary precision filter obtained by the invention has the advantages that the filter element in the fine filter cylinder is convenient to install and take out, the filter element can be quickly replaced, the fine filter quality is guaranteed, and the secondary precision filter has a more compact structure and is more convenient to use compared with the existing precision filter.

Description

Secondary precision filter

Technical Field

The invention relates to a filtering device, in particular to a secondary precision filter.

Background

Along with the social economic development, the family swimming pool, the district swimming pool appears in resident's urban life gradually, it is different with general commercial swimming pool, the volume of this kind of swimming pool is less relatively, the place is also comparatively limited, can't hold large-scale filtration equipment, also can't often adopt chemical mode to disinfect, therefore, need a less integrated form swimming pool water filtration equipment of volume, among the prior art, the universal adoption filters the sand and disinfects (filters) to swimming pool water, the great suspended solid of granule in this kind of filtration mode can the filtering swimming pool, however, to some tiny microorganism filter effects limitedly, for guaranteeing that user's is healthy, it is necessary to carry out the essence to swimming pool water.

Disclosure of Invention

The invention aims to solve the defects of the prior art and provide a secondary precision filter which has a compact structure and can effectively perform fine filtration on swimming pool water.

In order to achieve the purpose, the secondary precise filter comprises a sand cylinder, filter sand, a filter assembly and a control valve, wherein an opening is formed in the top of the sand cylinder, the filter sand is contained in the sand cylinder, the filter assembly comprises a filter piece, a water collecting pipe, a fine filter cylinder and a water outlet pipe, a plurality of filter pieces are distributed at one end of the water collecting pipe, the filter pieces are buried in the filter sand, a mounting port is formed in the side surface of the sand cylinder, the cylinder port end of the fine filter cylinder is fixed on the mounting port, the other end of the fine filter cylinder extends into the sand cylinder, the cylinder port of the fine filter cylinder is in sealed connection with the mounting port, a cylinder cover is in sealed connection with the mounting port, two pipe ports are formed in the fine filter cylinder and are respectively connected with the water collecting pipe and the water outlet pipe, a filter element of the fine filter cylinder is arranged at the bottom of the control valve, and a filter water inlet and a filter water outlet are further formed in the control valve, the connecting disc covers the opening and is in sealing connection with the opening, the water outlet pipe is communicated with the filtering water outlet, and the filtering water inlet is communicated with the inner cavity of the sand cylinder.

In order to make the whole filtering system compact in structure and convenient to control, the control valve comprises a valve body, a valve core, a valve cover and a control handle, wherein the valve cover covers the valve body and is connected with the valve body in a sealing way, and the valve body is provided with a sewage inlet, a waste water discharge port and a backflow discharge port; a sewage inlet chamber and a valve cavity are arranged in the valve body from top to bottom, the sewage inlet is communicated with the sewage inlet chamber, a support column and a waterproof plate are arranged in the valve cavity, the support column is positioned in the center of the valve cavity, the filtering water outlet is arranged on the support column, the waterproof plate extends from the support column to the inner wall of the valve body, thereby dividing the valve cavity into five areas distributed around the support column, namely a water inlet cavity, a waste water cavity, a closed area, a water outlet cavity and a return cavity in sequence, wherein the bottom area of the water inlet cavity is 2 times of that of the waste water cavity, the bottom areas of the waste water cavity and the backflow cavity are equal, the filtering water inlet is communicated with the water inlet cavity, the waste water discharge port is communicated with the waste water cavity, the filtering water outlet is communicated with the water outlet cavity, the backflow discharge port is communicated with the backflow cavity, the top of the closed area is provided with a closed plate, and the surface of the closed plate facing the sewage inlet chamber and the top of each waterproof plate form an interface of the sewage inlet chamber and the valve cavity; the case is installed in the sewage intake chamber, the case includes valve pad, valve plate and spring, the valve pad install in the valve plate bottom and with the interface butt, the valve plate is including relative through-hole and the circulation groove that sets up in the valve plate both sides, the valve plate top is equipped with the transfer line, the spring housing is established in the transfer line periphery, the valve plate top is equipped with the atress plane with the junction of transfer line, atress plane and spring one end butt, be equipped with the spring holder on the valve gap, the other end and the spring holder butt of spring, spring holder central authorities are equipped with and form hole axle complex shaft hole with the transfer line, be equipped with the sealing washer between transfer line and shaft hole, the transfer line passes and is connected with the handle bar transmission behind the shaft hole, be equipped with the fulcrum on the handle, fulcrum and valve gap surface contact.

In order to reduce the impact of water inflow on the filter sand, the bottom of the control valve is also provided with a water distribution net, the water distribution net is provided with water distribution holes, and the center of the water distribution net is provided with a guide pipe for a water outlet pipe to pass through.

In order to avoid the air in the sand cylinder to obstruct the water inlet, the water collecting pipe is provided with an exhaust pipe, the end part of the exhaust pipe is connected with a filtering exhaust head, and the filtering exhaust head is provided with an exhaust groove with the width smaller than the grain diameter of the filtering sand.

For convenient drainage, the sand cylinder bottom is equipped with the outlet, be equipped with the drain plug on the outlet, the drain plug includes eyebolt, fixation nut, blind nut, rubber buffer and filter screen, eyebolt passes and is equipped with the drainage sealing washer between outlet and eyebolt and sand cylinder, the filter screen sets up in the drainage hole in the middle of the eyebolt, fixation nut and eyebolt threaded connection and fix the eyebolt on the sand cylinder, blind nut and eyebolt stretch out the one end threaded connection of sand cylinder, the rubber buffer sets up between blind nut inboard and eyebolt tip.

For convenience and reliability, the connecting disc is fixedly connected with the opening through a pair of clamping rings, the clamping rings are connected and locked through a connecting bolt, the opening is provided with a folding edge, the clamping ring is provided with a clamping groove, the width of the groove opening of the clamping groove is larger than the width of the groove bottom, the folding edge and the connecting disc are clamped into the clamping groove after being aligned, and a tank body sealing ring is arranged between the folding edge and the connecting disc.

In order to install and seal the fine filter cylinder, a folding edge is arranged at the position of the cylinder opening, a limiting pipe structure is arranged on the installation opening, the top of the limiting pipe is abutted to the folding edge, a sealing ring is arranged between the top of the limiting pipe and the folding edge, limiting flanges are distributed on the folding edge in a surrounding mode, a guide flange corresponding to the limiting flanges is arranged at the top of the limiting pipe, when the fine filter cylinder is installed on the installation opening, the limiting flanges and the guide flange are mutually overlapped to form positioning buckles, positioning clamping grooves corresponding to the positioning buckles in quantity are distributed on the inner side of the cylinder cover, an inclined plane is arranged on one side, facing the sand cylinder, of the guide flange, and the contact surface of the positioning clamping grooves and the guide flange is a matched inclined plane in sliding fit with the inclined plane.

The secondary precise filter obtained by the invention realizes secondary precise filtration of swimming pool water by using the filter element inside the fine filter cylinder through arranging the fine filter cylinder, and meanwhile, the filter element in the fine filter cylinder is convenient to install and take out, so that the filter element can be quickly replaced, the fine filtration quality is ensured, compared with the existing precise filter, the secondary precise filter has a more compact structure and more convenient use, and can meet the use requirements of swimming pools in families and communities.

Drawings

FIG. 1 is a front view of a secondary precision filter embodiment 1 of the present invention;

FIG. 2 is a schematic view of the internal structure of embodiment 1;

fig. 3 is a perspective sectional view of a control valve in embodiment 1;

fig. 4 is a plan view of the valve body in embodiment 1;

FIG. 5 is a schematic view showing the internal structure of the secondary fine filter of example 2 of the present invention;

FIG. 6 is an enlarged schematic view at A in FIG. 5;

FIG. 7 is an enlarged schematic view at B in FIG. 5;

FIG. 8 is a rear view of embodiment 2 with the cover removed;

FIG. 9 is an enlarged schematic view at C of FIG. 8;

FIG. 10 is a schematic view showing the internal structure of the embodiment 2 from another angle;

fig. 11 is an enlarged schematic view at D in fig. 10.

In the figure: the filter comprises a sand cylinder 1, filter sand 2, a control valve 3, a filter element 4, a water collecting pipe 5, a fine filter cylinder 6, a water outlet pipe 7, a sealing ring 8, a water distribution net 9, a cylinder cover 10, a drain plug 11, a clamping ring 12, a connecting bolt 13, a cylinder body sealing ring 14, a sealing ring 15, a connecting disc 30, a control handle 35, a filter water inlet 31, a filter water outlet 32, a valve body 33, a valve cover 34, a supporting column 36, a waterproof plate 37, a valve plate 38, a valve pad 39, a spring 40, an exhaust pipe 50, a filter exhaust head 51, an exhaust groove 52, a filter element 60, a pipe interface 61, a folded edge 62, a limit flange 63, a water distribution hole 90, a guide pipe 91, an opening 100, a mounting port 101, a drain port 102, a folded edge 103, a guide flange 104, a positioning clamping groove 105, a perforated bolt 110, a fixing nut 111, a blind nut 112, a rubber plug 113, a filter screen 114, a drain sealing ring 115, a bolt drain hole 116, a clamping groove 120, a sewage inlet 330, a, The sewage treatment device comprises a waste water discharge port 331, a backflow discharge port 332, a sewage inlet chamber 333, an inlet cavity 334, a waste water cavity 335, an outlet cavity 336, a backflow cavity 337, a closing plate 338, a spring seat 340, a shaft hole 341, a fulcrum 350, a through hole 380, a circulation groove 381, a transmission rod 382, a stress plane 383 and a bevel 1040.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

Example 1:

the secondary precision filter described in this embodiment, as shown in fig. 1, includes a sand cylinder 1, filter sand 2, a filter assembly and a control valve 3, the top of the sand cylinder 1 is provided with an opening 100, the filter sand 2 is accommodated in the sand cylinder 1, the filter assembly includes a filter member 4, a water collecting pipe 5, a fine filter cylinder 6 and a water outlet pipe 7, one end of the water collecting pipe 5 is distributed with a plurality of filter members 4, the filter members 4 are embedded in the filter sand 2, a side surface of the sand cylinder 1 is provided with a mounting port 101, a cylinder port end of the fine filter cylinder 6 is fixed on the mounting port 101, the other end extends into the sand cylinder 1, a cylinder port of the fine filter cylinder 6 is hermetically connected with the mounting port 101, the mounting port 101 is hermetically connected with a cylinder cover 10, the fine filter cylinder 6 is provided with two pipe connectors 61, the two pipe connectors 61 are respectively connected with the water collecting pipe 5 and the water outlet pipe 7, the fine filter cylinder 6 is internally provided with a filter element 60, the bottom of the control valve 3 is provided with a connecting disc 30, the control valve 3 is also provided with a filtering water inlet 31 and a filtering water outlet 32, the connecting disc 30 covers the opening 100 and is hermetically connected with the opening 100, the water outlet pipe 7 is communicated with the filtering water outlet 32, and the filtering water inlet 31 is communicated with the inner cavity of the sand cylinder 1; in this embodiment, the filter element 4 may be a tube with meshes, and it should be understood that the purpose of the filter element 4 in the present invention is to prevent the filter sand 2 from entering the water collecting pipe 5, and it is well within the skill of those in the art to adjust the shape and the size of the meshes of the filter element 4, and even to replace the filtering function of the meshes with filter cotton, gauze, etc., without any creative work.

In order to make the whole filtering system compact in structure and convenient to control, the control valve 3 comprises a valve body 33, a valve core, a valve cover 34 and a control handle 35, wherein the valve cover 34 covers the valve body 33 and is hermetically connected with the valve body 33, and the valve body 33 is provided with a sewage inlet 330, a waste water discharge port 331 and a backflow discharge port 332; from top to bottom be equipped with sewage intake chamber 333 and valve pocket in the valve body 33, sewage import 330 intercommunication sewage intake chamber 333, be equipped with support column 36 and waterproof board 37 in the valve pocket, support column 36 is located the valve pocket central authorities, it sets up on support column 36 to filter out the mouth of a river 32, waterproof board 37 extends to valve body 33 inner wall from support column 36 to divide into the valve pocket and encircle support column 36 five regions of distribution, be intake chamber 334, waste water chamber 335, closed area, play water chamber 336 and backward flow chamber 337 in proper order, wherein the bottom area of intake chamber 334 is 2 times of waste water chamber 335 bottom area, the bottom area of waste water chamber 335 and backward flow chamber 337 equals, filters water inlet 31 and intake chamber 334 intercommunication, waste water discharge port 331 and waste water chamber 335 intercommunication, filters out mouth of a river 32 and play water chamber 336 intercommunication, backward flow discharge port 332 and backward flow chamber 337 intercommunication, is equipped with closed board 338 at the closed area top, the surface of the closing plate 338 facing the sewage inlet chamber 333 and the top of each waterproof plate 37 form an interface of the sewage inlet chamber 333 and the valve cavity; the valve core is arranged in the sewage inlet chamber 333, the valve core comprises a valve pad 39, a valve plate 38 and a spring 40, the valve pad 39 is arranged at the bottom of the valve plate 38 and is abutted against the interface, the valve plate 38 comprises a through hole 380 and a circulation groove 381 which are oppositely arranged at two sides of the valve plate 38, a transmission rod 382 is arranged at the top of the valve plate 38, the spring 40 is sleeved on the periphery of the transmission rod 382, a stress plane 383 is arranged at the joint of the top of the valve plate 38 and the transmission rod 382, the stress plane 383 is abutted against one end of the spring 40, a spring seat 340 is arranged on the valve cover 34, the other end of the spring 40 is abutted against the spring seat 340, a shaft hole 341 which forms a hole-shaft fit with the transmission rod 382 is arranged in the center of the spring seat 340, a sealing ring 8 is arranged between the transmission rod 382 and the shaft hole 341, the transmission rod 382 is in transmission connection with the operating handle 35 after penetrating through the shaft hole 341, and a fulcrum 350 is arranged on the operating handle 35, the fulcrum 350 is in surface contact with the valve cover 34.

In the actual working process, the control valve 3 at least comprises five working positions of closing, filtering, water circulation, backwashing and direct discharging, and the communication relation among the working positions is as follows:

1. closing the working position: the sewage inlet 330, the waste water discharge port 331, the backflow discharge port 332, the filtering water inlet 31 and the filtering water outlet 32 are all closed and blocked, and at the moment, all water paths in the control valve 3 are stopped, so that the filtering and draining functions are not realized;

2. a filtering work position: the sewage inlet 330 is communicated with the filtering water inlet 31 through a through hole 380, the filtering water outlet 32 is communicated with the wastewater discharge port 331 through a circulation groove 381, the backflow discharge port 332 is sealed by a valve plate 38, at the moment, sewage flows in from the sewage inlet 330, flows into the sand cylinder 1 through the filtering water inlet 31, is filtered by the filtering sand 2, flows into the fine filtering cylinder 6 through the filtering piece 4 and the water collecting pipe 5, and is subjected to secondary filtering by the filter element 60 in the fine filtering cylinder 6, wherein the filter element 60 can be made of materials such as filter paper, cotton, yarn and the like, and after the secondary filtering, water passes through the water outlet pipe 7 and is filtered out of the water outlet 32, and is finally discharged from the wastewater discharge port 331;

3. water circulation working position: the sewage inlet 330 is communicated with the filtering water inlet 31 through the through hole 380, the filtering water outlet 32 is communicated with the return discharge port 332 through the flow groove 381, the waste water discharge port 331 is closed by the valve plate 38, the sewage flows to the same phase as the filtering operation phase, but the filtered water is finally discharged into the swimming pool again from the return discharge port 332;

4. backwashing the working position: the sewage inlet 330 is communicated with the filtering water outlet 32 through a through hole 380, the filtering water inlet 31 is communicated with the wastewater discharge port 331 through a circulation groove 381, the backflow discharge port 332 is sealed, at the moment, purified water is pumped into the sewage inlet 330, the purified water reversely flows into the water outlet pipe 7 from the filtering water outlet 32, the water flowing into the water outlet pipe 7 flows into the filtering sand 2 through the empty fine filtering cylinder 6, the water collecting pipe 5 and the filtering piece 4, the filtering sand 2 is discharged through the filtering water inlet 31 and the wastewater discharge port 331 after being subjected to back washing, in the back washing process, in order to prevent the back washing water from impacting the filter element 60, the cylinder cover 10 can be opened firstly, the filter element 60 is taken out of the fine filtering cylinder 6, then the cylinder cover 60 and the mounting port 101 are sealed again, then the back washing is performed, and the taken-out filter element 60 can be replaced or cleaned independently and then put into a back washing finished system again;

5. straight row work position: at this time, the sewage inlet 330 and the waste water discharge port 331 are directly communicated, and waste water is directly discharged.

The switching of the working positions is carried out by manually rotating the operating lever so as to drive the valve core to rotate, when the working positions are switched, the operating lever is pressed down, the valve core is pried and rotated by relying on the fulcrum 350, in the process, the valve core and the interface of the sewage inlet chamber 333 and the valve cavity formed by the sealing plate 338 and the tops of the waterproof plates 37 are attached again after the operating handle 35 is loosened by the elasticity of the spring 40, and the sealing effect of the control valve 3 is ensured.

The secondary precision filter that this embodiment provided, through setting up essence section of thick bamboo 6, utilize its inside filter core 60 to realize straining the secondary essence of swimming pool water, filter core 60 installation in the essence section of thick bamboo 6 simultaneously with take out the convenience, can replace the filter core fast, guarantee essence strain the quality, current precision filter, the structure is more compact, it is more convenient to use, can satisfy the user demand of family, swimming pool in the district.

Example 2:

in the secondary precision filter described in this embodiment, as shown in fig. 4 and 5, in addition to the features described in embodiment 1, in order to reduce the impact of the inlet water on the filter sand 2, a water distribution net 9 is further disposed at the bottom of the control valve 3, a water distribution hole 90 is disposed on the water distribution net 9, and a guide pipe 91 through which the outlet water pipe 7 passes is disposed in the center of the water distribution net 9.

In order to avoid the obstruction of air in the sand cylinder 1 to water inlet, the water collecting pipe 5 is provided with an exhaust pipe 50, the end part of the exhaust pipe 50 is connected with a filtering exhaust head 51, and the filtering exhaust head is provided with an exhaust groove 52 with the width smaller than the grain diameter of the filtering sand 2.

In order to facilitate drainage, a drainage outlet 102 is formed in the bottom of the sand cylinder 1, a drainage plug 11 is arranged on the drainage outlet 102, the drainage plug 11 comprises a perforated bolt 110, a fixing nut 111, a blind nut 112, a rubber plug 113 and a filter screen 114, the perforated bolt 110 penetrates through the drainage outlet 102, a drainage sealing ring 115 is arranged between the perforated bolt 110 and the sand cylinder 1, the filter screen 114 is arranged in a drainage hole in the middle of the perforated bolt 110, the fixing nut 111 is in threaded connection with the perforated bolt 110 and fixes the perforated bolt 110 on the sand cylinder 1, the blind nut 112 is in threaded connection with one end, extending out of the sand cylinder 1, of the perforated bolt 110, and the rubber plug 113 is arranged between the inner side of the blind nut 112 and the end of the perforated nut.

For convenience and reliability in connection and fixation, the connecting disc 30 and the opening 100 are fixedly connected through a pair of clamping rings 12, the clamping rings 12 are connected and locked through connecting bolts 13, a folding edge 103 is arranged on the opening 100, a clamping groove 120 is arranged on the clamping ring 12, the width of a groove opening of the clamping groove 120 is larger than that of a groove bottom, the folding edge 103 and the connecting disc 30 are aligned and then clamped into the clamping groove 120, and a tank body sealing ring 14 is arranged between the folding edge 103 and the connecting disc 30.

In order to install and seal the fine filtering cylinder 6, a folding edge 62 is arranged at the cylinder opening, a limiting pipe structure is arranged on the installation opening 101, the top of the limiting pipe is abutted to the folding edge 62, a sealing ring 15 is arranged between the top of the limiting pipe and the folding edge 62, limiting flanges 63 are distributed on the folding edge 62 in a surrounding mode, guide flanges 104 corresponding to the limiting flanges 63 are arranged at the top of the limiting pipe, when the fine filtering cylinder 6 is installed on the installation opening 101, the limiting flanges 63 and the guide flanges 104 are mutually overlapped to form positioning buckles, positioning clamping grooves 105 corresponding to the positioning buckles in number are distributed on the inner side of the cylinder cover 10, an inclined plane 1040 is arranged on one side, facing the sand cylinder 1, of each guide flange 104, and the contact surfaces of the positioning clamping grooves 105 and the guide flanges 104 are matched inclined planes in sliding fit with the inclined plane 1040.

In the practical working process of the secondary precision filter provided by this embodiment, the control valve 3 can be used in cooperation with the water outlet 102 at the bottom of the sand cylinder 1 to positively wash the filtered sand 2 in the sand cylinder 1, at this time, in the control valve 3, the waste water port is communicated with the filtered water inlet 31 through the circulation groove 381, purified water is pumped into the sand cylinder 1 from the waste water port, the blind nut 112 is unscrewed, at this time, the rubber plug 113 is separated from the bolt drain hole 116 due to the loss of the axial position limitation of the blind nut 112, at this time, the water pumped into the sand cylinder 1 can be drained through the bolt drain hole 116, and at the same time, the filtered sand 2 is limited in the sand cylinder 1 by the filter screen 114 and cannot flow out along with the water; in addition, when the fine filter cylinder 6 is installed, the fine filter cylinder 6 is inserted into the installation hole along the limiting pipe, the water outlet pipe 7 and the water collecting pipe 5 are connected with the fine filter cylinder 6, the limiting flange 63 and the guide flange 104 are just overlapped, then the cylinder cover 10 is covered on the installation hole 101, the positioning buckle formed by overlapping is clamped into the positioning clamping groove 105 through rotation, due to the inclined plane 1040 and the matched inclined plane, along with the rotation of the cylinder cover 10, the positioning clamping groove 105 can press the positioning buckle structure, and therefore the limiting flange 63 and the guide flange 104 are tightly pressed.

Claims

1. A secondary precision filter comprises a sand cylinder (1), filter sand (2), a filter assembly and a control valve (3), and is characterized in that an opening (100) is formed in the top of the sand cylinder (1), the filter sand (2) is contained in the sand cylinder (1), the filter assembly comprises a filter piece (4), a water collecting pipe (5), a fine filter cylinder (6) and a water outlet pipe (7), a plurality of filter pieces (4) are distributed at one end of the water collecting pipe (5), the filter pieces (4) are buried in the filter sand (2), a mounting port (101) is formed in the side surface of the sand cylinder (1), the fine filter cylinder (6) is obliquely inserted into the sand cylinder (1), the cylinder port end of the fine filter cylinder (6) is fixed on the mounting port (101), the other end of the fine filter cylinder extends into the sand cylinder (1), the cylinder port of the fine filter cylinder (6) is hermetically connected with the mounting port (101), and a cylinder cover (10) is hermetically connected to the mounting port (101), the fine filter is characterized in that two pipe connectors (61) are arranged on the fine filter cylinder (6), the two pipe connectors (61) are respectively connected with a water collecting pipe (5) and a water outlet pipe (7), a filter element (60) is arranged in the fine filter cylinder (6), a connecting disc (30) is arranged at the bottom of the control valve (3), a filtering water inlet (31) and a filtering water outlet (32) are further arranged on the control valve (3), the connecting disc (30) covers the opening (100) and is in sealing connection with the opening (100), the water outlet pipe (7) is communicated with the filtering water outlet (32), and the filtering water inlet (31) is communicated with an inner cavity of the sand cylinder (1); the control valve (3) comprises a valve body (33), a valve core, a valve cover (34) and an operating handle (35), the valve cover (34) covers the valve body (33) and is in sealing connection with the valve body (33), and a sewage inlet (330), a waste water discharge port (331) and a backflow discharge port (332) are arranged on the valve body (33); the water filter is characterized in that a sewage inlet chamber (333) and a valve cavity are arranged in the valve body (33) from top to bottom, a sewage inlet (330) is communicated with the sewage inlet chamber (333), a waterproof plate (37) is arranged in the valve cavity, a water inlet cavity (334), a waste water cavity (335), a closed area, a water outlet cavity (336) and a backflow cavity (337) are sequentially distributed in the valve cavity in a surrounding manner, the waterproof plate (37) forms the water inlet cavity (334), the waste water cavity (335), the closed area, the water outlet cavity (336) and the backflow cavity (337), a filter water inlet (31) is communicated with the water inlet cavity (334), a waste water discharge port (331) is communicated with the waste water cavity (335), the backflow discharge port (332) is communicated with the backflow cavity (337), a filter water outlet (32) is communicated with the water outlet cavity (336), a closed plate (338) is arranged at the top of the closed area, and the closed plate (338) faces the surface of the sewage inlet chamber (333) and the top of each waterproof plate (37) to form a sewage inlet chamber (333) and a separating interface of the valve cavity, the valve core is arranged in the sewage inlet chamber (333), the valve core comprises a valve plate (38), and the valve plate (38) comprises a through hole (380) and a circulation groove (381) which are oppositely arranged on two sides of the valve plate (38).

2. The secondary precise filter of claim 1, wherein a supporting column (36) is further arranged in the valve cavity, the supporting column (36) is positioned in the center of the valve cavity, the filtering water outlet (32) is formed in the supporting column (36), the waterproof plate (37) extends from the supporting column (36) to the inner wall of the valve body (33), the bottom area of the water inlet cavity (334) is 2 times of that of the waste water cavity (335), and the bottom areas of the waste water cavity (335) and the return cavity (337) are equal; the valve core further comprises a valve pad (39) and a spring (40), the valve pad (39) is installed at the bottom of the valve plate (38) and abutted to the interface, a transmission rod (382) is arranged at the top of the valve plate (38), the spring (40) is sleeved on the periphery of the transmission rod (382), a stress plane (383) is arranged at the joint of the top of the valve plate (38) and the transmission rod (382), the stress plane (383) is abutted to one end of the spring (40), a spring seat (340) is arranged on the valve cover (34), the other end of the spring (40) is abutted to the spring seat (340), a shaft hole (341) matched with the transmission rod (382) in a hole-shaft manner is arranged in the center of the spring seat (340), a sealing ring (8) is arranged between the transmission rod (382) and the shaft hole (341), the transmission rod (382) is in transmission connection with the operating handle (35) after penetrating through the shaft hole (341), and a fulcrum (350) is arranged on the operating handle (35), the fulcrum (350) is in surface contact with the valve cover (34).

3. The secondary precision filter as claimed in claim 1 or 2, wherein the bottom of the control valve (3) is further provided with a water distribution net (9), the water distribution net (9) is provided with water distribution holes (90), and the center of the water distribution net (9) is provided with a guide pipe (91) for the water outlet pipe (7) to pass through.

4. The secondary precision filter according to claim 1 or 2, characterized in that the water collecting pipe (5) is provided with an exhaust pipe (50), the end part of the exhaust pipe (50) is connected with a filtering exhaust head (51), and the filtering exhaust head is provided with an exhaust groove (52) with the width smaller than the grain diameter of the filter sand (2).

5. The secondary fine filter according to claim 1 or 2, wherein a water outlet (102) is arranged at the bottom of the sand cylinder (1), a drain plug (11) is arranged on the drain outlet (102), the drain plug (11) comprises a perforated bolt (110), a fixing nut (111), a blind nut (112), a rubber plug (113) and a filter screen (114), the perforated bolt (110) passes through the water outlet (102) and a drainage sealing ring (115) is arranged between the perforated bolt (110) and the sand cylinder (1), the filter screen (114) is arranged in a drainage hole in the middle of the bolt (110) with the hole, the fixing nut (111) is in threaded connection with the perforated bolt (110) and fixes the perforated bolt (110) on the sand cylinder (1), the blind nut (112) is in threaded connection with one end of the bolt with the hole (110) extending out of the sand cylinder (1), the rubber stopper (113) is arranged between the inner side of the blind nut (112) and the end part of the nut with the hole.

6. The secondary precision filter of claim 1 or 2, wherein the connecting disc (30) is fixedly connected with the opening (100) through a pair of clamping rings (12), the clamping rings (12) are connected and locked through connecting bolts (13), a folding edge (103) is arranged on the opening (100), a clamping groove (120) is arranged on the clamping ring (12), the width of a groove opening of the clamping groove (120) is larger than the width of a groove bottom, the folding edge (103) is clamped into the clamping groove (120) after being aligned with the connecting disc (30), and a tank body sealing ring (14) is arranged between the folding edge (103) and the connecting disc (30).

7. The secondary precision filter as claimed in claim 1 or 2, wherein a flange (62) is arranged at the cylinder opening, a limiting pipe structure is arranged on the mounting opening (101), the top of the limiting pipe abuts against the flange (62), a sealing ring (15) is arranged between the top of the limiting pipe and the flange (62), a limiting flange (63) is further distributed on the flange (62) in a surrounding manner, a guide flange (104) corresponding to the limiting flange (63) is arranged at the top of the limiting pipe, when the fine filtering cylinder (6) is mounted on the mounting opening (101), the limiting flange (63) and the guide flange (104) are mutually overlapped to form positioning buckles, positioning clamping grooves (105) corresponding to the number of the positioning buckles are distributed on the inner side of the cylinder cover (10), an inclined surface (1040) is arranged on one surface of the guide flange (104) facing the sand cylinder (1), and the contact surface of the positioning clamping grooves (105) and the guide flange (104) is a matching inclined surface 1040) in sliding fit with the inclined surface (1040).