CN220633353U - Prefilter with back flush and self-cleaning function - Google Patents

Abstract

The utility model discloses a pre-filter with back flushing and self-cleaning functions, which comprises a pipeline joint, a filter flask, a flow director, an inner framework, an outer framework, a sewage joint and a ball valve, wherein the pipeline joint is connected with the filter flask; the front filter further comprises a lower sealing body, springs and a limiting sleeve, wherein the lower sealing body can be vertically and slidably connected to the inner side of the sewage joint, a plurality of throttling holes which are circumferentially distributed at intervals are formed in the lower sealing body, the springs are arranged between the lower sealing body and the sewage joint, the lower end of the inner framework movably penetrates through the outer framework and then is fixed with the lower sealing body, a plurality of spiral blades which are circumferentially distributed at intervals are arranged at the lower end of the outer framework, the limiting sleeve is fixed to the inner side of the upper end of the filter flask, a second filter screen which is fixed with the inner framework is sleeved on the outer wall of the upper end of the inner framework, and an annular convex edge is arranged on the outer wall of the inner framework between the second filter screen and the first filter screen; the utility model not only has the function of self-cleaning the first filter screen, but also has the function of back flushing the first filter screen.

Description

Prefilter with back flush and self-cleaning function

Technical Field

The utility model relates to the technical field of pre-filters, in particular to a pre-filter with back flushing and self-cleaning functions.

Background

Along with the improvement of the living standard of people, the water quality requirement on the living water is also high. Therefore, the prefilter is widely applied, and generally consists of a valve body and a filtering device arranged in the valve body, wherein a water inlet and a water outlet are arranged on the valve body, water flows in from the water inlet, and flows out from the water outlet after being filtered by the filtering device. Impurities such as rust, suspended matters, colloid substances and the like in the water can be blocked between the filtering device and the valve body. Over time, these impurities can stack up, affecting filtration efficiency; meanwhile, accumulated impurities easily pass through the filtering device under the flushing of water flow and flow out of the water outlet, so that the filtering effect is affected. In order to keep the filter working normally, the filter is often required to be disassembled periodically by manpower, the filter device and the valve body are manually cleaned, and the cleaning work is very tedious and time-consuming.

For this purpose, chinese patent publication No.: CN217041543U discloses a self-cleaning filter comprising a valve body, a filter assembly and a cleaning assembly; the valve body comprises a shell and a cover body, the cover body is connected to one end of the shell, and the cover body is provided with a water inlet and a water outlet; the filter assembly is arranged inside the shell and forms a first cavity with the shell, the interior of the filter assembly is hollow to form a second cavity, the first cavity is communicated with the water inlet, the second cavity is communicated with the water outlet, the filter assembly comprises a filter cylinder and a first blade which are integrally arranged, and the first blade is positioned at one end of the filter cylinder close to the water inlet and is spirally arranged; the cleaning component is rotatably arranged between the shell and the filtering component and is abutted with the filter cartridge and/or the shell, and the cleaning component is provided with a second blade which is positioned at the rear side of the first blade along the water flow direction and is used for driving the cleaning component to rotate; according to the self-cleaning filter, the filter cartridge and the first blade are integrally arranged, so that the self-cleaning filter is simpler and more compact in structure, the assembly work is simpler, the time cost is saved, and the assembly efficiency is improved. Meanwhile, the abrasion of the filter assembly and the rotation generating device at the joint in the original structure can be avoided, so that the service life of the self-cleaning filter is prolonged.

However, in the use process of the self-cleaning filter, the cleaning assembly is arranged, and the cleaning assembly can clean the filter assembly and the shell, but cannot back flush the filter assembly, so that the defect of poor cleaning effect on the filter assembly exists.

Disclosure of Invention

Aiming at the defects of the prior art, the utility model provides the pre-filter with the back flushing and self-cleaning functions, which not only has the function of self-cleaning the first filter screen, but also has the function of back flushing the first filter screen, thereby improving the cleaning effect of the first filter screen.

The utility model relates to a pre-filter with back flushing and self-cleaning functions, which comprises a pipeline joint, a filter flask, a flow director, an inner framework, an outer framework, a sewage joint and a ball valve; the pipe joint is provided with a water inlet, a water outlet and a connecting port, the flow director is arranged at the connecting port and is fixed with the pipe joint, and the outer wall of the flow director is provided with a plurality of flow guiding blades which are circumferentially distributed so as to generate a rotational flow effect on the water flow flowing through the flow director; the upper end of the filter flask is fixed with the connecting port and is sealed circumferentially; the lower end of the drain connector penetrates through the filter bottle and then extends out of the filter bottle, the upper end of the ball valve is fixed with the lower end of the filter bottle and is circumferentially sealed, and the drain connector is rotationally connected with the filter bottle and is circumferentially sealed; the inner framework is arranged in the filter flask and is positioned between the flow director and the sewage discharging joint, a first filter screen fixed with the inner framework is sleeved on the outer wall of the lower end of the inner framework, the outer framework is sleeved on the outer side of the inner framework and can rotate relative to the inner framework, a plurality of rubber scraping strips which are circumferentially distributed at intervals are fixed on the side wall of the outer framework, each rubber scraping strip extends along the vertical direction, the inner end part of each rubber scraping strip abuts against the outer wall of the first filter screen, and the outer end part of each rubber scraping strip abuts against the inner side wall of the filter flask; the front filter further comprises a lower sealing body, springs and a limiting sleeve, wherein the lower sealing body can be vertically and slidably connected to the inner side of the blowdown connector and circumferentially sealed with the blowdown connector, a plurality of throttling holes which are circumferentially and alternately distributed are formed in the lower sealing body, the springs are arranged between the lower sealing body and the blowdown connector, two ends of each spring are respectively abutted against the lower sealing body and the blowdown connector, the lower end of the inner framework movably penetrates through the outer framework and then is fixed with the lower sealing body, a plurality of spiral blades which are circumferentially and alternately distributed are arranged at the lower end of the outer framework, when water flows through the plurality of spiral blades, the plurality of spiral blades are used for driving the outer framework to rotate relative to the inner framework, the limiting sleeve is fixed to the inner side of the upper end of the filter flask, a second filter screen which is fixedly arranged on the outer wall of the upper end of the inner framework is sleeved with the inner framework, and an annular convex edge which is abutted against the inner edge of the limiting sleeve is arranged on the outer wall of the inner framework between the second filter screen and the first filter screen; when the ball valve is closed, water flow from the water inlet sequentially flows through the flow director, the gap between the annular convex edge and the limiting sleeve, the first filter screen and the inner framework and then is discharged from the water outlet; when the ball valve is opened, water flow from the water inlet sequentially flows through the flow guider, the second filter screen, the inner framework, the first filter screen, the spiral blade, the throttling hole and the blowdown connector and then is discharged from the ball valve.

By adopting the structure, the utility model not only has the function of self-cleaning the first filter screen, but also has the function of back flushing the first filter screen, thereby improving the cleaning effect of the first filter screen.

The utility model relates to a pre-filter with back flushing and self-cleaning functions, wherein the upper end of a flow director is provided with a clamping hook group which is matched and clamped with the inner wall of a connecting port, and the flow director is fixed with a pipeline joint through the clamping hook group; by adopting the structure, the flow guider can be reliably and conveniently fixed with the pipeline joint.

The utility model relates to a pre-filter with back flushing and self-cleaning functions, wherein the outer side wall of an outer framework is provided with caulking grooves which are in one-to-one correspondence with each rubber scraping strip, each rubber scraping strip is embedded in the caulking groove at the corresponding position, each caulking groove is provided with a scraping strip pressing plate, each scraping strip pressing plate is matched and clamped with the side wall of the caulking groove, each rubber scraping strip is tightly pressed in the caulking groove at the corresponding position through the scraping strip pressing plate at the corresponding position, and the outer end part of each rubber scraping strip extends out of the scraping strip pressing plate after penetrating through the scraping strip pressing plate at the corresponding position; by adopting the structure, each rubber scraping strip can be reliably pressed in the caulking groove at the corresponding position through the scraping strip pressing plate at the corresponding position.

The utility model relates to a pre-filter with back flushing and self-cleaning functions, wherein the lower end of an inner framework is provided with a pair of elastic buckles, the middle part of a lower sealing body is provided with a buckling hole, and the elastic buckles are movably penetrated through the lower end of an outer framework and then matched and buckled with the buckling hole; by adopting the structure, the lower end of the inner framework can be reliably and conveniently fixed with the lower sealing body.

The utility model relates to a pre-filter with back flushing and self-cleaning functions, wherein a sealing ring is embedded on the outer side wall of a lower sealing body, and the sealing ring is used for sealing a gap between the lower sealing body and a sewage joint; by adopting the structure, the sealing ring can reliably realize the sealing of the gap between the lower sealing body and the sewage discharging joint under the action of the sealing ring.

The utility model relates to a pre-filter with back flushing and self-cleaning functions, wherein the pre-filter further comprises a pressing ring, the lower end of the pressing ring is inserted into the upper end of an inner framework and is matched and clamped with the inner framework, the upper end of the pressing ring abuts against the upper end of a second filter screen, and the second filter screen is pressed on the inner framework through the pressing ring; by adopting such a structure, the second filter screen can be reliably pressed against the inner frame by the pressing ring.

The utility model relates to a pre-filter with back flushing and self-cleaning functions, wherein two elastic cantilevers which are circumferentially and alternately distributed are arranged at the upper end of a lower sealing body; through adopting this kind of structure, under the effect of elasticity cantilever, when the manual ball valve that rotates with making ball valve drive blowdown connect and lower seal body rotate towards the rotation direction of relative inner skeleton of outer skeleton, the free end of every elasticity cantilever homoenergetic is supported with one of them helical blade's lower extreme and is leaned on so that lower seal body drives outer skeleton and rotates together, promptly when there is more impurity in the filter flask so that the outer skeleton can not rotate relative inner skeleton because of being blocked, can make outer skeleton rotate relative inner skeleton through manual rotation ball valve, just so can scrape down the filth that will adhere to on first filter screen or filter flask inner wall by artificial intervention by force, so that outer skeleton can rotate relative inner skeleton again, in addition, when the reverse direction rotates the ball valve, elasticity cantilever can slide with helical blade between, can't drive outer skeleton and rotate promptly, also outer skeleton when independently rotating, the outer skeleton can not cause the influence to outer skeleton's rotation.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute an undue limitation to the application. In the drawings:

FIG. 1 is a schematic perspective view of the present utility model;

FIG. 2 is a schematic cross-sectional view of the present utility model;

FIG. 3 is a schematic cross-sectional view of the present utility model in a normal filtering state;

FIG. 4 is a schematic cross-sectional view of the present utility model in a blowdown state;

FIG. 5 is a schematic perspective cross-sectional view of the present utility model;

FIG. 6 is a schematic view of a first partially exploded perspective view of the present utility model with portions removed;

fig. 7 is a schematic view of a second partially exploded perspective view of the present utility model with portions removed.

Detailed Description

Various embodiments of the utility model are disclosed in the following drawings, in which details of the practice are set forth in the following description for the purpose of clarity. However, it should be understood that these practical details are not to be taken as limiting the utility model. That is, in some embodiments of the utility model, these practical details are unnecessary. Moreover, for the purpose of simplifying the drawings, some conventional structures and components are shown in the drawings in a simplified schematic manner.

In addition, the descriptions of the "first," "second," and the like, herein are for descriptive purposes only and are not intended to be specifically construed as order or sequence, nor are they intended to limit the utility model solely for distinguishing between components or operations described in the same technical term, but are not to be construed as indicating or implying any relative importance or order of such features. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions of the embodiments may be combined with each other, but it is necessary to base that the technical solutions can be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent and not within the scope of protection claimed in the present utility model.

As shown in fig. 1 to 7, the prefilter with back flushing and self-cleaning functions comprises a pipeline joint 1, a filter flask 2, a deflector 3, an inner framework 4, an outer framework 5, a sewage joint 6 and a ball valve 7; the pipeline joint 1 is provided with a water inlet 11, a water outlet 12 and a connecting port 13, the flow guider 3 is arranged at the connecting port 13 and is fixed with the pipeline joint 1, and the outer wall of the flow guider 3 is provided with a plurality of flow guiding blades 31 which are circumferentially distributed so as to generate a rotational flow effect on the water flow flowing through the flow guider 3; the upper end of the filter flask 2 is fixed with the connecting port 13 and is sealed circumferentially; the drain connector 6 is arranged at the inner bottom of the filter flask 2, the lower end of the drain connector 6 penetrates through the filter flask 2 and then extends out of the filter flask 2, the upper end of the ball valve 7 is fixed with the lower end of the filter flask 2 and is sealed circumferentially, and the drain connector 6 is connected with the filter flask 2 in a rotating manner and is sealed circumferentially; the inner framework 4 is arranged in the filter flask 2 and is positioned between the flow director 3 and the sewage discharging joint 6, the outer wall of the lower end of the inner framework 4 is sleeved with a first filter screen 41 fixed with the inner framework 4, the outer framework 5 is sleeved on the outer side of the inner framework 4, the outer framework 5 can rotate relative to the inner framework 4, the side wall of the outer framework 5 is fixedly provided with a plurality of rubber scraping strips 51 which are circumferentially distributed at intervals, each rubber scraping strip 51 extends along the vertical direction, the inner end part of each rubber scraping strip 51 abuts against the outer wall of the first filter screen 41, and the outer end part of each rubber scraping strip 51 abuts against the inner side wall of the filter flask 2; the front filter further comprises a lower sealing body 8, springs 9 and a limiting sleeve 10, wherein the lower sealing body 8 is vertically and slidably connected to the inner side of the blowdown connector 6 and is circumferentially sealed with the blowdown connector 6, a plurality of throttling holes 81 which are circumferentially and alternately distributed are formed in the lower sealing body 8, the springs 9 are arranged between the lower sealing body 8 and the blowdown connector 6, two ends of each spring 9 respectively prop against the lower sealing body 8 and the blowdown connector 6, the lower end of the inner framework 4 movably penetrates through the outer framework 5 and is fixed with the lower sealing body 8, a plurality of spiral blades 52 which are circumferentially and alternately distributed are arranged at the lower end of the outer framework 5, when water flows through the plurality of spiral blades 52, the plurality of spiral blades 52 are used for driving the outer framework 5 to rotate relative to the inner framework 4, the limiting sleeve 10 is fixed to the inner side of the upper end of the filter flask 2, a second filter screen 42 which is fixed with the inner framework 4 is sleeved on the outer wall of the upper end of the inner framework 4, and an annular convex edge 43 which props against the inner edge of the limiting sleeve 10 is arranged on the outer wall of the inner framework 4 between the second filter screen 42 and the first filter screen 41; when the ball valve 7 is closed, water flow from the water inlet 11 sequentially flows through the flow director 3, the gap between the annular convex edge 43 and the limiting sleeve 10, the first filter screen 41 and the inner skeleton 4 and then is discharged from the water outlet 12; when the ball valve 7 is opened, the water flow from the water inlet 11 sequentially passes through the deflector 3, the second screen 42, the inner frame 4, the first screen 41, the spiral vane 52, the orifice 81, and the drain joint 6, and then is discharged from the ball valve 7.

The upper end of the fluid director 3 is provided with a clamping hook group 32, the clamping hook group 32 is matched and clamped with the inner wall of the connecting port 13, and the fluid director 3 is fixed with the pipeline joint 1 through the clamping hook group 32; by adopting the structure, the flow guider can be reliably and conveniently fixed with the pipeline joint.

The outer side wall of the outer framework 5 is provided with caulking grooves 53 which are in one-to-one correspondence with each rubber scraping strip 51, each rubber scraping strip 51 is embedded in the caulking groove 53 at the corresponding position, each caulking groove 53 is provided with a scraping strip pressing plate 54, each scraping strip pressing plate 54 is matched and clamped with the side wall of the caulking groove 53, each rubber scraping strip 51 is tightly pressed in the caulking groove 53 at the corresponding position through the scraping strip pressing plate 54 at the corresponding position, and the outer end part of each rubber scraping strip 51 penetrates through the scraping strip pressing plate 54 at the corresponding position and then extends out of the scraping strip pressing plate 54; by adopting the structure, each rubber scraping strip can be reliably pressed in the caulking groove at the corresponding position through the scraping strip pressing plate at the corresponding position.

The lower end of the inner framework 4 is provided with a pair of elastic buckles 44, the middle part of the lower sealing body 8 is provided with buckling holes 82, and the elastic buckles 44 movably penetrate through the lower end of the outer framework 5 and then are matched and buckled with the buckling holes 82; by adopting the structure, the lower end of the inner framework can be reliably and conveniently fixed with the lower sealing body.

A sealing ring 83 is embedded on the outer side wall of the lower sealing body 8, and the sealing ring 83 is used for sealing a gap between the lower sealing body 8 and the sewage joint 6; by adopting the structure, the sealing ring can reliably realize the sealing of the gap between the lower sealing body and the sewage discharging joint under the action of the sealing ring.

The pre-filter further comprises a pressing ring 45, the lower end of the pressing ring 45 is inserted into the upper end of the inner framework 4 and is matched and clamped with the inner framework 4, the upper end of the pressing ring 45 abuts against the upper end of the second filter screen 42, and the second filter screen 42 is pressed on the inner framework 4 through the pressing ring 45; by adopting such a structure, the second filter screen can be reliably pressed against the inner frame by the pressing ring.

The upper end of the lower sealing body 8 is provided with two elastic cantilever arms 84 which are circumferentially and alternately distributed, and when the ball valve 7 is manually rotated to enable the ball valve 7 to drive the pollution discharge joint 6 and the lower sealing body 8 to rotate towards the rotation direction of the outer framework 5 relative to the inner framework 4, the free end of each elastic cantilever arm 84 is used for abutting against the lower end of one of the spiral blades 52 to enable the lower sealing body 8 to drive the outer framework 5 to rotate together; through adopting this kind of structure, under the effect of elasticity cantilever, when the manual ball valve that rotates with making ball valve drive blowdown connect and lower seal body rotate towards the rotation direction of relative inner skeleton of outer skeleton, the free end of every elasticity cantilever homoenergetic is supported with one of them helical blade's lower extreme and is leaned on so that lower seal body drives outer skeleton and rotates together, promptly when there is more impurity in the filter flask so that the outer skeleton can not rotate relative inner skeleton because of being blocked, can make outer skeleton rotate relative inner skeleton through manual rotation ball valve, just so can scrape down the filth that will adhere to on first filter screen or filter flask inner wall by artificial intervention by force, so that outer skeleton can rotate relative inner skeleton again, in addition, when the reverse direction rotates the ball valve, elasticity cantilever can slide with helical blade between, can't drive outer skeleton and rotate promptly, also outer skeleton when independently rotating, the outer skeleton can not cause the influence to outer skeleton's rotation.

When the filter is in a normal filtering state, namely when the ball valve is in a closed state, water enters from the water inlet on the pipe joint and flows through the flow guider, when the water flows through the flow guider, the water flow can generate a rotational flow effect under the action of the flow guide blades on the flow guider, the rotational flow enters the filter flask through the slit between the annular convex edge and the limiting sleeve and impacts the spiral blades on the outer framework, at the moment, the outer framework and the rubber scraping strip fixed on the outer framework can rotate relative to the inner framework, the rubber scraping strip can scrape impurities adsorbed on the outer surface of the first filter screen and the inner wall of the filter flask and enable the impurities to be settled at the bottom of the filter flask, and meanwhile, the water flow can enter the inner side of the first filter screen after being filtered by the first filter screen and finally is discharged through the water outlet on the pipe joint.

When the utility model is in a pollution discharge state, namely when the ball valve is in an open state, water enters from the water inlet on the pipeline joint and flows through the flow director, water flowing through the flow director can enter into the filter flask, and because the ball valve is in the open state, water in the filter flask can flow through the throttling hole on the lower end socket and the pollution discharge joint and then is discharged from the ball valve, when the water flows through the throttling hole, the water flow can form a pressure difference on the upper side and the lower side of the lower sealing body due to the throttling effect of the throttling hole, at the moment, the water flow can compress the spring and move downwards, when the lower sealing body moves downwards, the lower sealing body can drive the inner framework, the outer framework and the rubber scraping strip to move downwards due to the fact that the lower end of the inner framework is fixed with the lower sealing body, and when the inner framework moves downwards, the annular convex edge on the inner framework can finally abut against the limiting sleeve, and at the moment, the inner framework stops moving downwards, and the water from the deflector can not flow through the slit between the annular convex edge and the limiting sleeve, and because of the downward movement of the inner framework, the water from the deflector flows through the second filter screen and enters the inner side of the inner framework, the water entering the inner framework flows through the first filter screen from inside to outside, so that the water can flush impurities adsorbed on the outer wall of the first filter screen, the flushed impurities can be finally discharged from the ball valve along with the water, at the same time, under the action of the helical blades on the outer framework after the water flows into the first filter screen, the outer framework and the rubber scraping strips fixed on the outer framework can rotate relative to the inner framework, the rubber scraping strips can further scrape the impurities adsorbed on the outer surface of the first filter screen and the inner wall of the filter flask, the scraped impurities can be finally discharged from the ball valve along with the water, thereby realizing the cleaning of the outer wall of the first filter screen and the inner wall of the filter flask and the back flushing cleaning of the first filter screen; when the ball valve is closed, water flow stops flowing through the throttling hole on the lower sealing body, at the moment, the pressure difference on the upper side and the lower side of the lower sealing body disappears, the lower sealing body moves upwards to reset under the action of the spring, namely the inner framework, the outer framework and the rubber scraping strip also move upwards to reset, and the pre-filter is restored to a normal filtering state.

In addition, under the effect of elasticity cantilever, when the manual ball valve that rotates so that ball valve drive blowdown connect and lower seal body rotate towards the rotation direction of relative inner skeleton of outer skeleton, the free end of every elasticity cantilever all can lean on with one of them helical blade's lower extreme counterbalance so that lower seal body drives outer skeleton and rotates together, promptly when there is more impurity in the filter flask so that outer skeleton can't rotate relative inner skeleton because of being blocked, can make outer skeleton rotate relative inner skeleton through manual rotation ball valve, just so can scrape the filth that will adhere to on first filter screen or filter flask inner wall through artificial intervention by force, so that outer skeleton can rotate relative inner skeleton again, in addition, when the reverse direction rotates the ball valve, elasticity cantilever can slide with helical blade between, can't drive outer skeleton and rotate promptly, also outer skeleton is when independently rotating, the outer skeleton can not influence to outer skeleton's rotation.

The foregoing description is only illustrative of the utility model and is not to be construed as limiting the utility model. Various modifications and variations of the present utility model will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, or the like, which is within the spirit and principles of the present utility model, should be included in the scope of the claims of the present utility model.

Claims (7)

1. A pre-filter with back flushing and self-cleaning functions comprises a pipeline joint (1), a filter flask (2), a deflector (3), an inner framework (4), an outer framework (5), a sewage discharging joint (6) and a ball valve (7); the pipeline joint (1) is provided with a water inlet (11), a water outlet (12) and a connecting port (13), the flow guider (3) is arranged at the connecting port (13) and is fixed with the pipeline joint (1), and the outer wall of the flow guider (3) is provided with a plurality of flow guiding blades (31) which are circumferentially distributed so as to enable water flowing through the flow guider (3) to generate a rotational flow effect; the upper end of the filter flask (2) is fixed with the connecting port (13) and is sealed circumferentially; the sewage draining connector (6) is arranged at the inner bottom of the filter flask (2), the lower end of the sewage draining connector (6) penetrates through the filter flask (2) and then extends out of the filter flask (2), the upper end of the ball valve (7) is fixed with the lower end of the filter flask (2) and is sealed circumferentially, and the sewage draining connector (6) is connected with the filter flask (2) in a rotating manner and is sealed circumferentially; the inner framework (4) is arranged in the filter flask (2) and is positioned between the fluid director (3) and the sewage discharging joint (6), a first filter screen (41) fixed with the inner framework (4) is sleeved on the outer wall of the lower end of the inner framework (4), the outer framework (5) is sleeved on the outer side of the inner framework (4) and can rotate relative to the inner framework (4), a plurality of rubber scraping strips (51) which are circumferentially distributed at intervals are fixed on the side wall of the outer framework (5), each rubber scraping strip (51) extends along the vertical direction, the inner end part of each rubber scraping strip (51) abuts against the outer wall of the first filter screen (41), and the outer end part of each rubber scraping strip (51) abuts against the inner side wall of the filter flask (2); the method is characterized in that: the front filter further comprises a lower sealing body (8), a spring (9) and a limit sleeve (10), wherein the lower sealing body (8) can be vertically and slidably connected to the inner side of the sewage joint (6) and is circumferentially sealed with the sewage joint (6), a plurality of orifices (81) which are circumferentially distributed at intervals are arranged on the lower sealing body (8), the spring (9) is arranged between the lower sealing body (8) and the sewage joint (6) and two ends of the spring (9) are respectively abutted against the lower sealing body (8) and the sewage joint (6), the lower end of the inner framework (4) is movably connected with the outer framework (5) and then fixed with the lower sealing body (8), a plurality of spiral blades (52) which are circumferentially distributed at intervals are arranged at the lower end of the outer framework (5), when water flows through the spiral blades (52), the spiral blades (52) are driven to rotate relative to the inner framework (4), the limit sleeve (10) is fixed to the inner end of the inner framework (2), the second end of the inner framework (4) is fixed to the upper end of the inner framework (4), an annular convex edge (43) which is used for propping against the inner edge of the limit sleeve (10) is arranged on the outer wall of the inner framework (4) between the second filter screen (42) and the first filter screen (41); when the ball valve (7) is closed, water flow from the water inlet (11) sequentially flows through the flow director (3), the gap between the annular convex edge (43) and the limiting sleeve (10), the first filter screen (41) and the inner framework (4) and then is discharged from the water outlet (12); when the ball valve (7) is opened, water flow from the water inlet (11) sequentially flows through the flow director (3), the second filter screen (42), the inner framework (4), the first filter screen (41), the spiral blade (52), the throttling hole (81) and the sewage draining joint (6) and then is discharged from the ball valve (7).

2. The prefilter with backwash and self-cleaning functions according to claim 1, wherein a hook group (32) is arranged at the upper end of the deflector (3), the hook group (32) is clamped with the inner wall of the connection port (13) in a matched manner, and the deflector (3) is fixed with the pipeline joint (1) through the hook group (32).

3. The pre-filter with backwashing and self-cleaning functions according to claim 1, wherein the outer side wall of the outer framework (5) is provided with caulking grooves (53) corresponding to each rubber scraping strip (51) one by one, each rubber scraping strip (51) is embedded in the caulking groove (53) at the corresponding position, each caulking groove (53) is provided with a scraping strip pressing plate (54), each scraping strip pressing plate (54) is clamped with the side wall of the caulking groove (53) in a matched manner, each rubber scraping strip (51) is pressed in the caulking groove (53) at the corresponding position through the scraping strip pressing plate (54) at the corresponding position, and the outer end part of each rubber scraping strip (51) extends out of the scraping strip pressing plate (54) after penetrating through the scraping strip pressing plate (54) at the corresponding position.

4. The pre-filter with back flushing and self-cleaning functions according to claim 1, wherein a pair of elastic buckles (44) are arranged at the lower end of the inner framework (4), a buckling hole (82) is arranged in the middle of the lower sealing body (8), and the pair of elastic buckles (44) are buckled with the buckling hole (82) in a matched mode after movably penetrating through the lower end of the outer framework (5).

5. The prefilter with backwash and self-cleaning functions according to claim 1, wherein a sealing ring (83) is embedded on the outer side wall of the lower sealing body (8), and the sealing ring (83) is used for sealing a gap between the lower sealing body (8) and the drain joint (6).

6. The pre-filter with backwash and self-cleaning functions according to claim 1, further comprising a pressing ring (45), wherein the lower end of the pressing ring (45) is inserted into the upper end of the inner skeleton (4) and is clamped with the inner skeleton (4), the upper end of the pressing ring (45) abuts against the upper end of the second filter screen (42), and the second filter screen (42) is pressed on the inner skeleton (4) through the pressing ring (45).

7. The prefilter with backwash and self-cleaning functions according to any one of claims 1-6, wherein two elastic cantilevers (84) are arranged at the upper end of the lower sealing body (8) and are circumferentially spaced apart, and when the ball valve (7) is manually rotated to enable the ball valve (7) to drive the sewage draining joint (6) and the lower sealing body (8) to rotate towards the rotation direction of the outer skeleton (5) relative to the inner skeleton (4), the free end of each elastic cantilever (84) is used for abutting against the lower end of one of the spiral blades (52) to enable the lower sealing body (8) to drive the outer skeleton (5) to rotate together.