CN215781917U - Two-sided leading filter of scraping and washing - Google Patents

Abstract

The application relates to the technical field of water treatment, and relates to a double-sided scraping and washing pre-filter which comprises a shell, and a water inlet end and a water outlet end which are arranged on two sides of the upper end of the shell, wherein a filter screen cylinder is erected in the shell, a space is reserved between the filter screen cylinder and the inner wall of the shell, a filter screen is wrapped on the surface of the filter screen cylinder, a first water inlet and a back flushing hole are formed in the top of the filter screen cylinder, a double-sided scraping blade is arranged in the shell, and the scraping blade is made of a soft material; the width of the scraping blade is larger than the distance between the outer wall of the scraping blade and the outer wall of the filter screen; the top of the shell is provided with a stroke hole communicated with the inner space of the shell, and an internal thread is arranged in the stroke hole; when the pre-filter is used for backwashing, the opening of a sewage discharge outlet and the double-sided spiral scraping can be simultaneously realized by rotating the knob, dirt and impurities on the outer wall of the filter screen are cleaned by the double-sided spiral scraping in the process of flushing and sewage discharge, when the sewage discharge mechanism needs to be disassembled, the clamp spring structure is pulled out, the second knob is pulled outwards, and the valve core and the knob are simple and convenient to install, disassemble or replace.

Description

Two-sided leading filter of scraping and washing

Technical Field

The application relates to the technical field of water treatment, in particular to a double-sided scraping and washing pre-filter.

Background

The first coarse filtration equipment of the pre-filter for the water used in the whole house can filter large granular substances such as silt, rust and the like in tap water, and is generally installed at the front end of a pipeline, the water in the pipeline firstly enters a filter screen cylinder through a water inlet end of the pre-filter and then is filtered by the filter screen cylinder, the water flow finally flows out from a water outlet end for use, a filter screen on the filter screen cylinder is continuously contacted with impurities in the filtering process of the filter screen cylinder, the impurities even cover a filter screen port of the filter screen cylinder in the past, the water flow cannot flow out of the filter screen cylinder in a large flow, the water pressure is reduced, and even the filter screen cylinder is blocked, in order to ensure the normal use of the filter screen cylinder, the filter screen cylinder needs to be cleaned,

when the conventional pre-filter needs to be cleaned, a filter screen cylinder is generally cleaned in a back-flushing mode, but some stubborn dirt is attached to the outer wall of the filter screen, and the outer wall of the filter screen is extremely difficult to be flushed by water flow which flushes outwards from the filter screen cylinder, so that the filter screen cannot be cleaned completely; impurities washed by a backwashing mode can be discharged from a sewage discharge outlet, and the front filter can be switched to a flushing and sewage discharge state from a normal filtering state only by rotating a knob at the top end of the front filter, so that if the front filter needs to perform backwashing work, control switches such as the knob and a valve need to be opened at the same time, the process of flushing and sewage discharge of the front filter becomes troublesome due to the existence of a plurality of control switches, the workload of users is increased, the switching time is prolonged, and the cleaning efficiency of the front filter is influenced;

the drain of traditional leading filter all can be provided with the valve for opening and close of control drain, if direct mode through rivers back flush washes a filter screen section of thick bamboo, need open the valve of drain department earlier, leading filter equipment among the prior art, the case and the knob spiro union of blowdown ball valve, the knob is as vulnerable part, need the unscheduled change, but the knob installation, the dismantlement and the change of the blowoff valve of prior art need professional instrument cooperation, the operation is inconvenient.

SUMMERY OF THE UTILITY MODEL

The utility model aims to overcome the defects of the prior art and provides a double-sided scraping pre-filter.

The utility model provides a double-sided scraping and washing pre-filter, which comprises a shell, a water inlet end and a water outlet end, wherein the water inlet end and the water outlet end are arranged on two sides of the upper end of the shell, a filter screen cylinder is erected in the shell, a space is reserved between the filter screen cylinder and the inner wall of the shell, a plurality of filter holes are uniformly distributed in the filter screen cylinder, and a filter screen is wrapped on the surface of the filter screen cylinder, and the double-sided scraping and washing pre-filter is characterized in that: the top of the filter screen cylinder is provided with a first water inlet, the side wall close to the first water inlet is provided with a plurality of back washing holes communicated with the inner space of the first water inlet, the top of the shell is provided with a stroke hole communicated with the inner space of the shell, and the stroke hole is internally provided with an internal thread; a valve rod is arranged at the center of the top of the filter screen cylinder; the outer wall of the lower part of the valve rod is provided with an external thread which is in threaded connection with the internal thread, and the upper part of the valve rod penetrates through the stroke hole and is connected with a first knob;

an opening is formed below the filter screen cylinder, and a pollution discharge plug is screwed at the opening; the bottom of the shell is provided with a sewage discharge outlet communicated with the inner space of the shell, and the sewage discharge outlet is sealed and blocked by the sewage discharge plug;

the two side surfaces of the upper end of the sewage discharge plug are symmetrically provided with limiting lugs, a brush rod is arranged in a brush rod fixing hole on the limiting lugs, a brush strip is sleeved on the brush rod, the movable brush strip is movably connected with the brush rod,

the outer wall of the upper part of the filter screen cylinder is provided with a snap ring; the brush strip is positioned between the snap ring and the limiting lug; movable intervals are arranged among the brush strip, the clamping ring and the limiting lug;

and a joint is arranged below the sewage draining outlet and communicated with a sewage draining pipeline, and a sewage draining mechanism is arranged on the sewage draining pipeline.

Further, the brush bar is provided with a mounting part and a cleaning part, the mounting part is provided with a sleeve hole matched with the brush rod, the sleeve hole is sleeved on the brush rod, the bottom of the brush rod is provided with an anti-falling screw, the cleaning part is provided with a scraping blade, the scraping blade is made of soft materials, and the width of the scraping blade is larger than the distance between the outer wall of the scraping blade and the outer wall of the filter screen;

further, screw holes are formed in the valve rod and the center of the top of the first knob and penetrate through the screw holes through screws for fixing;

furthermore, a protective cover is arranged on the outer ring of the joint, an installation opening is formed in the bottom surface of the protective cover, and the inner diameter of the installation opening is larger than the outer diameter of the joint; the boot length is greater than the connector length.

Further, the pollution discharge mechanism comprises a valve shell, a valve core and a valve core driving shaft are arranged in the valve shell, a second knob is arranged on one side of the valve shell,

the valve casing comprises a valve casing assembling part and a limiting groove, the valve casing assembling part is an annular bulge, the lower side of the bulge is provided with a penetrating groove,

a limiting groove is arranged below the side surface of the valve shell assembling part,

the second knob comprises a rotating part and a knob assembling part, an annular clamping groove is formed in the outer part of the knob assembling part, and an assembling hole is formed in the end part of the knob assembling part;

the assembly hole arranged on the knob assembly part, the annular bulge arranged on the valve shell assembly part and the valve core driving shaft are axially connected and penetrate through the penetrating groove through a clamp spring structure to be fixed with the limiting groove and the annular clamping groove; the valve core driving shaft and the second knob rotate synchronously relative to the valve shell.

Further, still be equipped with spacing convex body in the valve casing assembly portion, knob assembly portion is equipped with spacing mouthful along the circumference for the rotation angle of control second knob through the cooperation of spacing convex body and spacing mouthful.

Furthermore, the width of the limiting opening accounts for one fourth of the circumference of the knob assembling part and is used for controlling the rotating angle of the second knob to be 90 degrees;

compared with the prior art, the utility model has the beneficial effects that:

(1) the double-sided scraping pre-filter adopting the structure of the utility model can realize the backwashing by the scraping strips arranged on the two sides, the dirt and impurities on the outer wall of the filter screen are scraped, and along with the process that the filter screen cylinder moves upwards for several circles and moves downwards for several circles, can completely scrape and wash the outer wall of the filter screen, completely remove dirt and impurities on the outer wall of the filter screen, and shift up the in-process at the filter screen section of thick bamboo, not only can make the scraping strip scrape the washing to the filter screen outer wall, and enable the back flush hole relative with the play water end, convert the filtration state of leading filter into and wash the blowdown state, more can open the drain simultaneously, need not to go to open the valve of drain department again after converting to and washing the blowdown state, realized the effect of a switch simultaneous control a plurality of positions, can effectively simplify leading filter's structure, make manufacturing cost obtain reducing, more can effectively reduce leading filter operation degree of difficulty and improve operating efficiency.

(2) The pollution discharge mechanism prevents the second knob from falling off by arranging the clamp spring structure, and when the second knob needs to be disassembled, the clamp spring structure is pulled out, and the second knob is pulled outwards; the blowdown mechanism of the device has reasonable design, the valve core and the knob are easy and convenient to install, disassemble or replace, and the use is convenient.

Drawings

The utility model is illustrated and described only by way of example and not by way of limitation in the scope of the utility model as set forth in the following drawings, in which:

FIG. 1: the utility model has a schematic structure;

FIG. 2: the utility model discloses a structural schematic diagram of a pollution discharge mechanism;

in the figure: 1-housing, 2-water inlet end, 3-water outlet end, 4-screen cylinder, 5-screen, 6-backwash hole, 8-stroke hole, 9-internal thread, 10-valve stem, 11-external thread, 12-first knob, 13-opening, 14-blowdown plug, 15-blowdown port, 16-screw, 17-joint, 18-protective cover, 19-mounting port, 20-snap ring, 31-limit lug, 32-brush bar, 33-brush bar, 41-valve housing, 42-second knob, 43-snap ring structure, 411-valve housing assembly, 412-limit groove, 421-knob assembly, 422-rotating part, 423-annular snap groove,

Detailed Description

In order to make the objects, technical solutions, design methods, and advantages of the present invention more apparent, the present invention will be further described in detail by specific embodiments with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the utility model and are not intended to limit the utility model.

As shown in fig. 1-2, the utility model provides a double-sided scraping and washing prefilter, which comprises a shell 1, and a water inlet end 2 and a water outlet end 3 which are arranged on two sides of the upper end of the shell 1, wherein a filter screen cylinder 4 is erected in the shell 1, a gap is formed between the filter screen cylinder 4 and the inner wall of the shell 1, a plurality of filter holes which are uniformly distributed are arranged on the filter screen cylinder 4, and a filter screen 5 is wrapped on the surface of the filter screen cylinder 4, and the prefilter is characterized in that: the top of the filter screen cylinder 4 is provided with a first water inlet, the side wall close to the first water inlet is provided with a plurality of back washing holes 6 communicated with the inner space of the first water inlet, the top of the shell 1 is provided with a stroke hole 8 communicated with the inner space of the shell 1, and the stroke hole 8 is internally provided with an internal thread 9; a valve rod 10 is arranged at the center of the top of the filter screen cylinder 4; the outer wall of the lower part of the valve rod 10 is provided with an external thread 11 which is in threaded connection with the internal thread 9, and the upper part of the valve rod 10 penetrates through the stroke hole 8 and is connected with a first knob 12;

an opening 13 is formed below the filter screen cylinder 4, and a pollution discharge plug 14 is screwed at the opening 13; a sewage discharge outlet 15 communicated with the inner space of the shell 1 is formed in the bottom of the shell, and the sewage discharge plug 14 seals and blocks the sewage discharge outlet 15;

a joint 17 is arranged below the sewage discharge port 15, the joint 17 is communicated with a sewage discharge pipeline, and a sewage discharge mechanism is arranged on the sewage discharge pipeline;

the two side surfaces of the upper end of the sewage discharge plug 14 are symmetrically provided with a pair of limiting lugs 31, a brush rod 32 is arranged in a brush rod fixing hole on the limiting lugs 31, a movable brush strip 33 is sleeved on the brush rod 32, the movable brush strip 33 is movably connected with the brush rod 32,

the outer wall of the upper part of the filter screen cylinder 4 is provided with a snap ring 20; the brush strip 33 is positioned between the snap ring 20 and the limiting lug 31; the brush strip 33, the snap ring 20 and the limiting lug 31 are respectively provided with a movable distance;

further, the brush bar 33 is provided with a mounting part and a cleaning part, the mounting part is provided with a sleeve hole matched with the brush rod 32, the sleeve hole is sleeved on the valve rod 32, the bottom of the valve rod 32 is provided with an anti-falling screw 34, the cleaning part is provided with a scraping blade, the scraping blade is made of soft materials, and the width of the scraping blade is larger than the distance between the outer wall of the scraping blade and the outer wall of the filter screen 5;

it should be noted that the snap ring 20 and the limiting lug 31 can achieve the effect of limiting up and down, and avoid the situation that the internal and external threads are separated due to too many rotation turns when a user scrapes and washes the filter screen cylinder 4, when the user moves the filter screen cylinder 4 up by a certain distance through the first knob 12, the brush bar 33 moves down, the lower edge of the brush bar 33 will contact with the upper surface of the limiting lug 31, and at this time, the user can clearly feel the resistance from the first knob 12, and then can rotate the filter screen cylinder 4 down through the first knob 12, when the brush bar 33 of the filter screen cylinder 4 moves up, and when the upper edge of the brush bar 33 contacts with the lower surface of the snap ring 20 in the moving down process, the user can clearly feel the resistance, and if the user wants to continue to scrape and wash the filter screen cylinder, the user can continue to move up the filter screen cylinder;

further, screw holes are formed in the centers of the tops of the valve rod 10 and the first knob 12 and are fixed through screws 16;

furthermore, a protective cover 18 is sleeved outside the joint 17, an installation opening 19 is formed in the bottom surface of the protective cover 18, and the inner diameter of the installation opening 19 is larger than the outer diameter of the joint 17; the length of the protective cover 18 is greater than that of the joint 17; it should be noted that the joint 17 is arranged at the sewage discharge port 15, and the existence of the joint 17 can quickly realize the connection between the sewage discharge port 15 and the sewage discharge pipeline, so that the sewage can be conveniently discharged to an actually required position through the sewage discharge pipeline;

a protective cover is sleeved outside the joint 17, a mounting opening 19 is formed in the bottom surface of the protective cover 18, the inner diameter of the mounting opening 19 is larger than the outer diameter of the joint 17, the length of the protective cover 18 is larger than that of the joint 17, the protective cover 18 can shield the connecting position between the joint 17 and the sewage discharge pipeline, so that the connecting position between the joint 17 and the sewage discharge pipeline is protected, and the condition that the sewage discharge pipeline falls off due to the fact that a user or other things touch the connecting position carelessly is avoided;

further, the pollution discharge mechanism comprises a valve housing 41, a valve core arranged in the valve housing 41, a second knob 42 for driving the valve core to rotate and a clamp spring structure 43, wherein the second knob 42 comprises a rotating part 422 and a knob assembling part 421, an annular clamp groove 423 is arranged outside the knob assembling part 421, and an assembling hole matched with the valve core driving shaft is arranged at the end part of the knob assembling part 421; the valve casing 41 is provided with a valve casing assembling portion 411 matched with the knob assembling portion 421, and the side surface of the valve casing assembling portion 411 is provided with a limiting groove 412; the knob assembly part 421, the valve casing assembly part 411 and the valve core driving shaft are axially connected and fixed by the matching of the snap spring structure 43, the limiting groove 412 and the annular clamping groove 423; the spool drive shaft and second knob 42 rotate synchronously relative to the valve housing; it should be noted that the snap spring structure 43 prevents the second knob 42 from falling off, when the second knob 42 needs to be detached, the snap spring structure 43 is pulled out, and the second knob 42 is pulled outwards, the assembly hole is a kidney-shaped hole or a multi-variable hole, and the second knob 42 is integrally injection-molded by hard plastics;

further, a limiting convex body is further arranged in the valve housing assembling portion 411, a limiting opening is arranged along the circumference of the knob assembling portion 421, and the limiting convex body is matched with the limiting opening to control the rotation angle of the second knob 42;

further, the width of the limiting opening occupies one fourth of the circumference of the knob assembling portion 421, and is used for controlling the rotation angle of the second knob 42 to be 90 °, namely, the second knob rotates clockwise 90 °, so as to open the valve core; the valve core is turned over 90 degrees, so that the valve core is closed;

the working process is as follows: before the pre-filter is used, the pre-filter is installed on a pipeline through a water inlet end 2 and a water outlet end 3, at the moment, a back washing hole 6 of the pre-filter is blocked by the inner wall of a shell 1, when water flows into the shell 1 from the water inlet end 2, the water flows into a filter screen cylinder 4 through an inlet at the upper end of the filter screen cylinder 4, finally, the water flows into the inner space of the shell 1 through a filter screen 5 in the filter screen cylinder 4, once the water flows through the filter screen 5, the filter screen 5 has a filtering effect, a sewage discharge plug 14 blocks a sewage discharge port 15, and as the inner space of the shell 1 is continuously filled with the water flows, the water flows out of the water outlet end 3 finally and flows into the corresponding pipeline for use;

when the pre-filter needs to be backwashed for cleaning a filter screen cylinder, a user can rotate a first knob 12, as the first knob 12 is connected with a valve rod 10, when the first knob 12 is rotated, the valve rod 10 rotates along with the first knob, an external thread 11 at the lower part of the valve rod 10 is in threaded connection with an internal thread 9 on the inner wall of a stroke hole 8, the valve rod 10 can move up and down along the track of the internal thread and the external thread when rotating, the filter screen cylinder 4 moves up and down along the track of the upper thread and the lower thread when the valve rod 10 moves up and down, when the user controls the filter screen cylinder 4 to move up through the first knob 12, a sewage discharge plug 14 screwed below the filter screen cylinder 4 moves up along with the track of the internal thread, the sewage discharge plug 14 does not block and seal a sewage discharge outlet 15, the sewage discharge outlet 15 is communicated with the internal space of the shell 1, and the upper end of the filter screen cylinder is staggered with the upward movement of the filter screen cylinder, and a water inlet end 2 cannot feed water into the filter screen cylinder 4, the backwashing hole 6 is moved to a position opposite to the water outlet end 3, water in a pipeline connected with the water outlet end 3 is backwashed into the water outlet end 3 and enters the filter screen cylinder 4 through the backwashing hole 6, along with the continuous entering of water flow into the filter screen cylinder 4, the water pressure of the water flow continuously scours the inner wall of the filter screen cylinder 4, scoured impurities are brought out of the filter screen cylinder 4 through the screen opening of the filter screen 5, and the water flow also scours the impurities in the screen opening of the filter screen 5 in the process of passing through the screen opening of the filter screen 5;

in the rotation process of the filter screen cylinder 4, a pair of lugs 32 are oppositely arranged on two side surfaces of the upper end of the pollution discharge plug 14, a brush rod 7 is arranged on each lug 32 through a brush rod fixing hole, a movable brush strip 6 is sleeved on each brush rod 7, each brush rod 7 is movably connected with the corresponding movable brush strip 6, each brush strip 6 is provided with an installation part and a cleaning part, each installation part is a sleeve hole matched with each brush rod and is sleeved on the corresponding valve rod 7 through the corresponding sleeve hole, an anti-falling screw 8 is arranged at the bottom of each valve rod 7, a scraping piece is arranged on each cleaning part, and each scraping piece is made of soft materials; because the doctor blade is fixed and the width of the doctor blade is larger than the distance between the outer wall of the doctor blade and the outer wall of the filter screen 5, the doctor blade can be fully contacted with the outer wall of the filter screen 5, the doctor blade contacted with the doctor blade can form a reaction force along with the centrifugal force generated by the rotation of the filter screen cylinder 4, and the scraping force of the doctor blade can be improved under the action of the reaction force, thereby improving the cleaning quality, when the doctor blade continuously scrapes the surface of the filter screen 5, the doctor blade can scrape off the dirt impurities attached to the outer wall of the filter screen 5, so that the fallen dirt impurities are also mixed into the water flow, and the doctor blade is made of a soft material, the doctor blade can not damage the outer wall of the filter screen while scraping the outer wall of the filter screen 5, under the condition of the soft material of the doctor blade, the doctor blade can deform, and the contact between the doctor blade and the outer wall of the filter screen 5 is converted into the contact between the surface and the surface, the scraping and washing range is wider, the scraping and washing efficiency is higher, the outer wall of the filter screen 5 can be completely cleaned by rotating the filter screen cylinder 4 for one circle, a user can completely clean dirt and impurities on the outer wall of the filter screen 5 only by rotating the filter screen cylinder 4 up and down for several circles through the first knob 12, the drain outlet 15 and the inner space of the filter screen cylinder 4 are in a communicated state along with the upward movement of the filter screen cylinder, at the moment, the drain outlet 15 is opened, water in the drain outlet 15 passes through the joint 17, the connection between the drain outlet 15 and a drain pipeline is quickly realized, and the impurities and the dirt are discharged from the drain outlet along with water flow through a drainage mechanism arranged on the drain pipeline;

the utility model can scrape dirt and impurities on the outer wall of the filter screen 5 in the back washing process by the scraping strip, and along with the process that the filter screen cylinder 4 moves upwards for a plurality of circles and moves downwards for a plurality of circles, can completely scrape and wash the outer wall of the filter screen 5 and completely remove dirt and impurities on the outer wall of the filter screen 5, in the process of moving the filter screen cylinder 4 upwards, the scraping strips 7 can scrape and wash the outer wall of the filter screen 5, and the back flush hole 6 is opposite to the water outlet end 3, the filtering state of the pre-filter is converted into a flushing and pollution discharging state, the sewage outlet 15 can be opened simultaneously, a valve at the position of the sewage outlet 15 does not need to be opened after the filtering state of the pre-filter is converted into the flushing and pollution discharging state, the effect that one switch controls a plurality of parts simultaneously is realized, the structure of the pre-filter can be effectively simplified, the production cost is reduced, the operation difficulty of the pre-filter can be effectively reduced, and the operation efficiency is improved.

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.

Claims (7)

1. The utility model provides a two-sided leading filter of scraping, includes casing (1) and locates intake end (2), play water end (3) of casing (1) upper end both sides, and casing (1) inner tower is equipped with filter screen cylinder (4), has the interval between filter screen cylinder (4) and casing (1) inner wall, is equipped with a plurality of evenly distributed's filtration pore on filter screen cylinder (4), and filter screen cylinder (4) surface coating has filter screen (5), its characterized in that: a first water inlet is formed in the top of the filter screen cylinder (4), a plurality of back washing holes (6) communicated with the inner space of the first water inlet are formed in the side wall close to the first water inlet, a stroke hole (8) communicated with the inner space of the shell (1) is formed in the top of the shell (1), and an internal thread (9) is formed in the stroke hole (8); a valve rod (10) is arranged at the center of the top of the filter screen cylinder (4); the outer wall of the lower part of the valve rod (10) is provided with an external thread (11) which is in threaded connection with the internal thread (9), and the upper part of the valve rod (10) penetrates through the stroke hole (8) and is connected with a first knob (12);

an opening (13) is formed below the filter screen cylinder (4), and a pollution discharge plug (14) is screwed at the opening (13); a sewage discharge outlet (15) communicated with the inner space of the shell (1) is formed in the bottom of the shell, and the sewage discharge plug (14) seals and blocks the sewage discharge outlet (15);

the two side surfaces of the upper end of the sewage discharge plug (14) are symmetrically provided with limiting lugs (31), a brush rod (32) is arranged in a brush rod fixing hole on the limiting lugs (31), a brush strip (33) is sleeved on the brush rod (32), the brush strip (33) is movably connected with the brush rod (32),

the outer wall of the upper part of the filter screen cylinder (4) is provided with a snap ring (20); the brush rod (32) is positioned between the clamping ring (20) and the limiting lug (31); the brush strip (33), the snap ring (20) and the limiting lug (31) are all provided with movable intervals;

a connector (17) is arranged below the sewage draining port (15), the connector (17) is communicated with a sewage draining pipeline, and a sewage draining mechanism is arranged on the sewage draining pipeline.

2. The pre-filter of claim 1, wherein the brush bar (33) is provided with a mounting part and a cleaning part, the mounting part is provided with a sleeve hole matched with the brush rod (32), the sleeve hole is sleeved on the brush rod (32), the bottom of the brush rod (32) is provided with an anti-falling screw, the cleaning part is provided with a scraping blade, the scraping blade is made of soft material, and the width of the scraping blade is larger than the distance between the outer wall of the scraping blade and the outer wall of the filter screen (5).

3. A double-sided scratchpad prefilter according to claim 1 wherein screw holes are provided in the valve stem (10) and in the centre of the top of the first knob (12) and through which screws (16) are fastened.

4. A double-sided scraping pre-filter according to claim 1, characterized in that a protective cover (18) is sleeved outside the joint (17), a mounting opening (19) is formed in the bottom surface of the protective cover (18), and the inner diameter of the mounting opening (19) is larger than the outer diameter of the joint (17); the length of the protective cover (18) is larger than that of the joint (17).

5. A double-sided scratchback prefilter according to claim 1, wherein said drainage mechanism comprises a valve housing (41), a valve element and a valve element driving shaft being provided in said valve housing (41), a second knob (42) being provided on one side of the valve housing (41),

the valve casing (41) comprises a valve casing assembling part (411) and a limit groove (412), the valve casing assembling part (411) is an annular bulge, the lower side of the bulge is provided with a penetrating groove,

a limit groove (412) is arranged below the side surface of the valve shell assembling part (411),

the second knob (42) comprises a rotating part (422) and a knob assembling part (421), an annular clamping groove (423) is formed in the outer part of the knob assembling part (421), and an assembling hole is formed in the end part of the knob assembling part (421);

an assembly hole arranged in the knob assembly part (421), an annular bulge arranged in the valve shell assembly part (411) and the valve core driving shaft are axially connected and penetrate through the penetrating groove through a clamp spring structure (43) to be fixed with the limiting groove (412) and the annular clamping groove (423); the spool drive shaft and the second knob (42) rotate synchronously with respect to the valve housing (41).

6. The double-sided scratchback prefilter of claim 5, wherein: still be equipped with spacing convex body in valve casing assembly portion (411), knob assembly portion (421) are equipped with spacing mouthful along the circumference for the rotation angle of control second knob (42) through the cooperation of spacing convex body and spacing mouthful.

7. The double-sided scratchback prefilter of claim 6, wherein: the width of the limiting opening accounts for one fourth of the circumference of the knob assembling part (421) and is used for controlling the rotating angle of the second knob (42) to be 90 degrees.

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