CN218130325U - Double-filter-screen pre-filter - Google Patents

Abstract

The utility model relates to a leading filter of two filter screens. It has been solved and has used the raw water to wash the technical problem such as pollution that causes to the filter core now. Including having the water inlet, the filter housing of delivery port and drain, be equipped with the filter core body in the filter housing, the filter core body inboard has the filtration main cavity and has to be located at filter core body circumference and filters the outlying main filter screen of main cavity, well core rod is worn to be equipped with in the internal activity of filter core, well core rod upper end inboard has the vice chamber of filtration that is linked together with the water inlet, circumference has to be located to filter the vice chamber outlying vice filter screen at well core rod upper end, be equipped with between well core rod and the filter core body and can be linked together and can block the drain and filter the main cavity and filter the filtration that the main cavity is linked together when the drain opens and wash switching mechanism. Has the advantages that: through two net filtration, the secondary pollution has been avoided for the water purification after filtering to the sparge water, forms the orifice through the washout hole and improves the directive property, realizes high-speed back flush.

Description

Double-filter-screen pre-filter

Technical Field

The utility model belongs to the technical field of leading filter equipment, concretely relates to leading filter of two filter screens.

Background

Before running water reaches every user through the pipe network, passed through a lot of pipelines, there are impurity such as a lot of silt, iron rust, plankton in the pipeline, can cause the water pollution if do not carry out filtration treatment. The pre-filter is adopted to filter at the source of the household water, so that the secondary pollution can be effectively eliminated, the water pollution diseases are reduced, the solid impurities can be removed, the safety of a pipeline system is protected, and the system maintenance cost is reduced.

After the long-time work of current leading filter, the impurity that carries in the raw water inlays in the mesh of filter core, causes the filter core to be blockked up easily. When clean filter core, generally to leading in the filter backward the raw water that lets in as the washing liquid, utilize the raw water to wash the filter core, but because also contain certain impurity in the raw water, impurity in the raw water can block up the opposite side of filter screen once more when washing, and not only original tiny particle impurity that blocks up in the mesh can't effectively be washed and still can produce new impurity like this, has aggravated the filter core and has blockked up and also caused secondary pollution. In addition, most of the existing pre-filters are pre-filters with single filter screen mechanisms, so that the filtering efficiency is low and the using effect is poor.

In order to solve the defects of the prior art, people have long searched for and put forward various solutions. For example, chinese patent literature discloses a backwash-capable prefilter [201620215059.7], which comprises a housing, a transmission rod penetrating through the housing, a filter element disposed on the outer periphery of the transmission rod, a purified water passage formed between the outer wall of the filter element and the inner wall of the housing, a raw water passage formed between the inner wall of the filter element and the outer wall of the transmission rod, a knob for rotating the transmission rod fixedly connected to the transmission rod, a water inlet and a water outlet provided on the knob, the knob being rotatable relative to the housing to switch the water inlet sequence, a lower cover for fixing the filter element in the housing provided at the bottom of the housing, a drain provided on the lower cover, and a ceramic switch for controlling the drain to open and close connected to the other end of the transmission rod.

Above-mentioned scheme has solved the downthehole tiny particle impurity of current filter screen to a certain extent and can't washed clean scheduling problem, but this scheme still has a great deal of not enough, for example the filtration efficiency is low, uses raw water to wash the filter core and causes secondary pollution scheduling problem easily.

Disclosure of Invention

The utility model aims at the above-mentioned problem, provide a leading filter of double screen.

In order to achieve the above purpose, the utility model adopts the following technical proposal: the utility model provides a leading filter of two filter screens, is including the filter housing who has water inlet, delivery port and drain, the filter housing in be equipped with the filter element body, filter element body outside and filter housing between be equipped with the water purification chamber that is linked together with the delivery port, the filter element body inboard have and filter the main chamber and have in filter element body circumference and be located and filter the outlying main filter screen of main chamber, wear to be equipped with well core rod in the internal activity of filter element, well core rod upper end inboard have the vice chamber of filtration that is linked together with the water inlet, circumference has to be located main filter screen top and is located and filters vice chamber outlying vice filter screen in well core rod upper end, well core rod and filter element between be equipped with and can be linked together when the drain and can block the vice chamber of filtration and filter the filtration that the main chamber is linked together with filtering the main chamber and filter the main chamber and wash the switching mechanism with filtering when the drain opens. Under the filter state, main filter screen and vice filter screen all can carry out the raw water and filter, realize that the twin-wire gauze filters simultaneously, wash the switching that switching mechanism filters and the blowdown through filtering, wash under the state, realize the water purification after vice filter screen filters the raw water and wash, have avoided the raw water to get into the water purification chamber like this and have caused the secondary water pollution.

In foretell leading filter of two filter screens, the filtration wash switching mechanism include and link to each other and the activity sets up the inboard movable filter core in filter element body upper end circumference with well core rod upper end, just filtration accessory chamber form in the movable filter core, just movable filter core and filter element body between be equipped with the main and accessory chamber that enables to filter accessory chamber and filter the main cavity intercommunication or block when the core rod oscilaltion, well core rod pass through the setting of elasticity movable mounting subassembly at the filter core internally. When the drain is opened or closed, the main cavity and the auxiliary cavity can be freely opened and closed by the elastic movable mounting assembly and the central rod, and the switching between the filtering mode and the draining mode is further controlled.

In foretell leading filter of two filter screens, main auxiliary chamber open and close the subassembly including setting up the filter core shrouding that is located main filter screen upper end inboard in filter core body upper end circumference, be equipped with a plurality of main cavity water conservancy diversion holes just in filter core shrouding circumference activity filter core lower extreme be equipped with a plurality of main cavity shutoff portions with main cavity water conservancy diversion hole one-to-one, activity filter core lower extreme be equipped with a plurality of respectively with the auxiliary cavity water conservancy diversion hole of main cavity water conservancy diversion hole one-to-one dislocation set, just the filter core shrouding on be equipped with a plurality of auxiliary cavity shutoff portions with auxiliary cavity water conservancy diversion hole one-to-one.

In the above-mentioned double-screen prefilter, the peripheral outer side of the movable filter element and the peripheral inner side of the filter element body are connected in a sealing and sliding manner, and the auxiliary screen is arranged on the peripheral inner side or the peripheral outer side of the movable filter element.

In foretell leading filter of two filter screens, elasticity movable mounting subassembly including setting up the well core rod movable hole at filter core shrouding center, well core rod about the activity wear to locate well core rod movable hole in, just well core rod lower extreme be equipped with and enable well core rod keep having the elasticity roof pressure mechanism of activity filter core direction motion trend towards.

In the double-filter-screen pre-filter, the elastic jacking mechanism comprises a movable base arranged at the lower end of the central rod, the movable base is provided with a sewage discharge guide hole communicated with the sewage discharge outlet, and a jacking spring is arranged between the lower ends of the movable bases. The central rod moves upwards through a top pressure spring at the bottom and drives the movable filter element at the same time, so that a filtering mode is realized; or the water pressure of the opened sewage draining outlet is changed to drive the movable filter element to move downwards and drive the central rod at the same time, so that a sewage draining mode is realized.

In the above-mentioned leading filter of two filter screens, main filter screen set up at filter element body circumference inboard, just filter element body circumference outside be equipped with and wash water conservancy diversion mechanism.

In foretell leading filter of two filter screens, wash water conservancy diversion mechanism including the cover locate the filter element body circumference outside wash the support body, wash support body upper end and filter element body upper end between be formed with the water conservancy diversion chamber of washing that is linked together with filtering vice chamber, wash water conservancy diversion chamber and be located main filter screen circumference outlying water conservancy diversion subassembly of washing and be linked together. The clean water from the movable filter element enters the washing diversion cavity to carry out back washing, thereby avoiding secondary pollution caused by washing.

In foretell leading filter of two filter screens, wash and form two arc clearances that correspond the setting between support body upper end circumference inboard and the filter core body upper end circumference outside, just thereby arc clearance upper and lower ends seal through the sealing washer respectively and form the aforesaid and wash the water conservancy diversion chamber. The upper end and the lower end of the washing diversion cavity are sealed by the sealing rings, and the purified water can only flow into the washing groove of the washing frame body from the washing diversion cavity, so that the washing pressure of the purified water is improved.

In foretell leading filter of two filter screens, wash water conservancy diversion subassembly include a plurality of vertical formation in the frame support bar that washes in the frame circumference outside, wash and be equipped with the washtrough of vertical setting on the frame support bar, thereby the removable closed strip that can seal the washtrough and form and wash the water conservancy diversion chamber and be linked together of washing the passageway of washing in the washtrough outside, just wash passageway upper end and extend to the arc water conservancy diversion portion department that washes frame upper end circumference inboard, be equipped with a plurality of vertical extensions respectively and set up and with wash the washing hole that the passageway is linked together washing one side that the frame support bar kept away from the closed strip, just the washing hole perpendicular to main filter screen respectively. The flushing hole is wide outside and narrow inside, effectively promotes the directive property of sparge water, forms a row of orifice under the cooperation of water pressure again.

Compared with the prior art, the utility model has the advantages of:

1. raw water flows outwards from the inner wall of the filter element body, the raw water is accumulated in the inner wall of the filter element body, and meanwhile, the auxiliary filter screen at the upper end of the central rod can also filter, so that double-net simultaneous filtration is realized, the filtration area is increased, the water flow is enhanced, and the filtration and water purification capacity is improved.

2. When washing the filter screen, the reverse flush water is the clean water after vice filter screen filters, has avoided secondary pollution, and reverse flush water pressure equals water supply pressure simultaneously, and the pressure boost forms the orifice and improves the directive property on the filter brush after washing the hole, realizes high-speed back flush, and the filter brush of deuterogamying carries out 360 degrees scrubs and washes, strengthens blowdown efficiency.

3. After the sewage draining exit is opened, the central rod automatically runs downwards along with the water flow pressure to start a sewage draining mode; after the drain is closed, the water pressure difference becomes small, the central rod moves upwards along with the top pressure spring, the filtering mode is automatically opened, the operation structure is simple, and the operation and the use are easy.

Drawings

Fig. 1 is a schematic structural diagram of the present invention.

Fig. 2 is a structural sectional view of the present invention.

Fig. 3 is a schematic structural view of the movable filter element of the present invention.

Fig. 4 is a schematic structural diagram of the center rod of the present invention.

Fig. 5 is a schematic structural diagram of the middle filter element body of the present invention.

Fig. 6 is a schematic structural view of the middle washing frame body of the present invention.

Fig. 7 is a sectional view of the structure of the middle filtering mode and the water source direction of the present invention.

Fig. 8 is a structural sectional view of the sewage discharge mode and the water source direction of the present invention.

In the figure: the filter comprises a filter shell 1, a water inlet 11, a water outlet 12, a water purification cavity 121, a sewage discharge outlet 13, a filter element body 2, a main filtering cavity 21, a main filtering screen 211, an auxiliary filtering screen 22, an auxiliary filtering screen 221, a flushing guide mechanism 23, a flushing frame body 24, an arc-shaped gap 241, a sealing ring 242, a flushing guide cavity 25, a central rod 3, a filtering and flushing switching mechanism 4, a movable filter element 41, a main cavity plugging part 411, an auxiliary cavity guide hole 412, a main and auxiliary cavity opening and closing assembly 5, a filter element sealing plate 51, a main cavity guide hole 511, an auxiliary cavity plugging part 512, an elastic movable mounting assembly 6, a central rod movable hole 61, an elastic jacking mechanism 62, a movable base 621, a sewage discharge guide hole 6211, a jacking spring 622, a flushing guide assembly 7, a flushing frame support bar 71, a flushing groove 72, a flushing channel 73, a sealing bar 74, an arc-shaped guide part 75 and a flushing hole 76.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

As shown in fig. 1-8, a dual-strainer front filter, including a filter housing 1 having a water inlet 11, a water outlet 12 and a sewage outlet 13, a filter element body 2 is provided in the filter housing 1, a clear water chamber 121 communicating with the water outlet 12 is provided between the outer side of the filter element body 2 and the filter housing 1, a main strainer 21 located at the periphery of the main strainer 21 is provided at the inner side of the filter element body 2, a central rod 3 is movably inserted in the filter element body 2, an auxiliary filtering chamber 22 communicating with the water inlet 11 is provided at the inner side of the upper end of the central rod 3, an auxiliary strainer 221 located above the main strainer 211 and located at the periphery of the auxiliary filtering chamber 22 is provided at the upper end of the central rod 3 in the circumferential direction, a filtering flushing mechanism 4 is provided between the central rod 3 and the filter element body 2, which can communicate the auxiliary filtering chamber 22 and the main filtering chamber 21 when the sewage outlet 13 is closed, and can communicate the auxiliary filtering chamber 22 and the main filtering chamber 21 when the sewage outlet 13 is opened, thereby blocking the sewage outlet 13 and the main filtering flushing mechanism communicating with the filtering chamber 21. Obviously, under the filtering state, both main filter screen 211 and auxiliary filter screen 211 can carry out raw water filtration, realize that the twin-wire filters simultaneously, under the state of washing, realize that the water purification is washed after auxiliary filter screen 221 filters the raw water, avoided like this that the raw water gets into water purification chamber 121 and causes the secondary water pollution.

As shown in fig. 2, the filtering and flushing switching mechanism 4 includes a movable filter element 41 connected to the upper end of the central rod 3 and movably disposed on the inner side of the upper end of the filter element body 2 in the circumferential direction, and a filtering auxiliary cavity 22 is formed in the movable filter element 41, a main and auxiliary cavity opening and closing assembly 5 is disposed between the movable filter element 41 and the filter element body 2, the main and auxiliary cavity opening and closing assembly enables the filtering auxiliary cavity 22 and the filtering main cavity 21 to be communicated or blocked when the central rod 3 ascends and descends, and the central rod 3 is disposed in the filter element body 2 through an elastic movable mounting assembly 6. When the drain 13 is opened or closed, the main cavity and the auxiliary cavity opening and closing assembly 5 can be freely used by the central rod 3 through the elastic movable mounting assembly 6, and the switching between the filtering mode and the draining mode is further controlled.

Referring to fig. 3 and 5, the main and auxiliary chamber opening and closing assembly 5 includes a filter element closing plate 51 disposed on the upper end of the filter element body 211 and disposed on the inner side of the circumference of the upper end of the filter element body 2, a plurality of main chamber diversion holes 511 are disposed in the circumference of the filter element closing plate 51, the lower end of the movable filter element 41 is provided with a plurality of main chamber plugging portions 411 corresponding to the main chamber diversion holes 511 one to one, the lower end of the movable filter element 41 is provided with a plurality of auxiliary chamber diversion holes 412 staggered with the main chamber diversion holes 511 one to one, and the filter element closing plate 51 is provided with a plurality of auxiliary chamber plugging portions 512 corresponding to the auxiliary chamber diversion holes 412 one to one.

Wherein, the outer side of the movable filter element 41 in the circumferential direction and the inner side of the filter element body 2 in the circumferential direction are connected in a sealing and sliding manner, and the auxiliary filter screen 221 is arranged on the inner side or the outer side of the movable filter element 41 in the circumferential direction. For example, it is preferable that the sub-screen 221 is provided on the inner circumferential side of the movable filter element 41, so that the movable filter element 41 is lifted and lowered, and the outer circumferential side of the movable filter element 41 and the inner circumferential side of the filter element body 2 are sealed by a seal ring.

With reference to fig. 4 and 5, the elastic movable mounting assembly 6 includes a central rod movable hole 61 disposed at the center of the filter core sealing plate 51, the central rod 3 is movably inserted into the central rod movable hole 61, and the lower end of the central rod 3 is provided with an elastic pressing mechanism 62 capable of keeping the central rod 3 moving toward the direction of the movable filter core 41.

The elastic pressing mechanism 62 includes a movable base 621 disposed at the lower end of the central rod 3, the movable base 621 has a sewage guide hole 6211 communicated with the sewage outlet 13, and a pressing spring 622 is disposed between the lower ends of the movable bases 621. The central rod 3 moves upwards through a top pressure spring 622 at the bottom and drives the movable filter 41 core at the same time, thereby realizing a filtering mode; or, the sewage draining outlet 13 is opened, the water pressure is changed, the movable filter element 41 is driven to move downwards, and the center rod 3 is driven at the same time, so that the sewage draining mode is realized.

As shown in fig. 2, the main screen 211 is disposed on the inner side of the filter element body 2 in the circumferential direction, and the flushing guide mechanism 23 is disposed on the outer side of the filter element body 2 in the circumferential direction.

Particularly, wash water conservancy diversion mechanism 23 including the cover locate 2 circumference outsides of filter element body wash the support body 24, wash and be formed with between support body 24 upper end and the 2 upper ends of filter element body and filter the vice chamber 22 of being linked together wash water conservancy diversion chamber 25, wash water conservancy diversion chamber 25 and be located main filter screen 211 circumference outlying and wash water conservancy diversion subassembly 7 and be linked together. The clean water from the movable filter element 41 enters the washing diversion cavity 25 to carry out back washing, thereby avoiding secondary pollution during washing.

As shown in fig. 6, two arc gaps 241 are correspondingly formed between the inner circumferential side of the upper end of the washing frame body 24 and the outer circumferential side of the upper end of the filter element body 2, and the upper and lower ends of the arc gaps 241 are respectively sealed by the sealing rings 242 to form the washing diversion cavity 25. The upper and lower ends of the washing diversion cavity 25 are sealed by the sealing rings 242, and the clean water can only flow into the washing groove 72 of the washing frame body 24 from the washing diversion cavity 25, so that the clean water washing pressure is improved.

Wherein, wash water conservancy diversion subassembly 7 and include a plurality of vertical formation in washing the frame support bar 71 that washes of the 24 circumference outsides of frame body, wash and be equipped with the washing groove 72 of vertical setting on the frame support bar 71, thereby washing groove 72 outside removable be equipped with can seal washing groove 72 and form with wash the closed strip 74 of washing passageway 73 that water conservancy diversion chamber 25 is linked together, and wash passageway 73 upper end and extend to wash the inboard arc water conservancy diversion portion 75 of 24 upper end circumference of frame body, wash one side that frame support bar 71 kept away from closed strip 74 and be equipped with a plurality of vertical extensions respectively and set up and with wash the washing hole 76 that passageway 73 is linked together, and wash hole 76 respectively perpendicular to main filter screen 211. The flushing holes 76 are of a structure with wide outside and narrow inside, so that the directivity of flushing water is effectively improved, and a row of spraying holes are formed under the cooperation of water pressure.

The principle of the embodiment is as follows:

combine shown in fig. 7, during the filtration state, close drain 13, roof pressure spring 622 drives well core rod 3 and movable filter core 41 rebound, movable filter core 41 and filter core shrouding 51 part, filter main cavity 21 and filter vice chamber 22 intercommunication each other, the raw water directly gets into from water inlet 11 and filters main cavity 21 and filter in the vice chamber 22, main filter screen 211 filters simultaneously with vice filter screen 221 double net, the raw water filters from inside to outside, discharge from delivery port 12 through clear water chamber 121, thereby realize the filtration mode.

Combine shown in fig. 8, during the state of washing, it changes to open drain 13 water pressure differential pressure, activity filter core 41 receives the water pressure influence to move down and supports each other with filter core shrouding 51 and lean on, it does not communicate each other with filtering vice chamber 22 to filter main cavity 21, well core rod 3 moves down simultaneously and drives movable base 621, the raw water gets into the vice filter screen 221 through activity filter core 41 from water inlet 11 and produces the water purification, flow to washing passageway 73 through washing hole 76 through washing water conservancy diversion chamber 25 afterwards and wash towards filtering main cavity 21 direction, filter impurity flows into drain 13 through blowdown water conservancy diversion hole 6211, thereby realize blowdown mode.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications, additions and substitutions may be made by those skilled in the art to the specific embodiments described without departing from the spirit of the invention or exceeding the scope of the invention as defined in the accompanying claims.

Although the terms of the filter housing 1, the water inlet 11, the water outlet 12, the clean water cavity 121, the sewage draining outlet 13, the filter element body 2, the main filtering cavity 21, the main filtering net 211, the auxiliary filtering cavity 22, the auxiliary filtering net 221, the flushing guide mechanism 23, the flushing frame body 24, the arc-shaped gap 241, the sealing ring 242, the flushing guide cavity 25, the central rod 3, the filtering and flushing switching mechanism 4, the movable filter element 41, the main cavity blocking part 411, the auxiliary cavity guide hole 412, the main and auxiliary cavity opening and closing assembly 5, the filter element closing plate 51, the main cavity guide hole 511, the auxiliary cavity blocking part 512, the elastic movable mounting assembly 6, the movable central rod hole 61, the elastic jacking mechanism 62, the movable base 621, the sewage guide hole 6211, the jacking spring 622, the flushing guide assembly 7, the flushing frame support bar 71, the flushing groove 72, the flushing channel 73, the closing bar 74, the arc-shaped guide part 75, and the flushing hole 76 are used more frequently, the possibility of using other terms is not excluded. These terms are used merely to more conveniently describe and explain the nature of the present invention; they are to be construed as being without limitation to any one of the additional limitations of the present invention.

Claims (10)

1. A pre-filter with double filter screens comprises a filter shell (1) with a water inlet (11), a water outlet (12) and a sewage outlet (13), wherein a filter element body (2) is arranged in the filter shell (1), it is characterized in that a water purifying cavity (121) communicated with the water outlet (12) is arranged between the outer side of the filter element body (2) and the filter shell (1), the inner side of the filter core body (2) is provided with a main filtering cavity (21) and a main filter screen (211) which is positioned at the periphery of the main filtering cavity (21) is arranged at the periphery of the filter core body (2), a central rod (3) is movably arranged in the filter element body (2) in a penetrating way, the inner side of the upper end of the central rod (3) is provided with a filter auxiliary cavity (22) communicated with the water inlet (11), an auxiliary filter screen (221) which is positioned above the main filter screen (211) and is positioned at the periphery of the auxiliary filtering cavity (22) is arranged at the upper end of the central rod (3) in the circumferential direction, thereby well core rod (3) and filter element body (2) between be equipped with and can be linked together filtering vice chamber (22) and filtering main cavity (21) when drain (13) are closed and can block filtering vice chamber (22) and filtering main cavity (21) when drain (13) are opened and filter that drain (13) and filtering main cavity (21) are linked together and wash switching mechanism (4).

2. The pre-filter with double filter screens as in claim 1, wherein the filtering and flushing switching mechanism (4) comprises a movable filter element (41) which is connected with the upper end of the central rod (3) and is movably arranged on the circumferential inner side of the upper end of the filter element body (2), the filtering auxiliary cavity (22) is formed in the movable filter element (41), a main and auxiliary cavity opening and closing component (5) which can enable the filtering auxiliary cavity (22) and the filtering main cavity (21) to be communicated or blocked when the central rod (3) ascends and descends is arranged between the movable filter element (41) and the filter element body (2), and the central rod (3) is arranged in the filter element body (2) through an elastic movable mounting component (6).

3. The pre-filter with double filter screens as claimed in claim 2, wherein the main and auxiliary chamber opening and closing assembly (5) comprises a filter element closing plate (51) arranged at the circumferential inner side of the upper end of the filter element body (2) and located at the upper end of the main filter screen (211), a plurality of main chamber flow guide holes (511) are arranged at the circumferential inner side of the filter element closing plate (51), a plurality of main chamber plugging portions (411) corresponding to the main chamber flow guide holes (511) one by one are arranged at the lower end of the movable filter element (41), a plurality of auxiliary chamber flow guide holes (412) staggered with the main chamber flow guide holes (511) one by one are arranged at the lower end of the movable filter element (41), and a plurality of auxiliary chamber plugging portions (512) corresponding to the auxiliary chamber flow guide holes (412) one by one are arranged on the filter element closing plate (51).

4. A double screen prefilter as claimed in claim 2 wherein said movable filter element (41) is sealingly and slidably associated with said circumferentially inner side of said core (2) and said secondary screen (221) is disposed circumferentially inwardly or outwardly of said movable filter element (41).

5. The double-filter-screen prefilter of claim 3 or 4 wherein said resilient movably mounted element (6) comprises a central rod moving hole (61) provided in the center of the filter element closing plate (51), said central rod (3) being movably inserted into the central rod moving hole (61) in an up-and-down manner, and said central rod (3) being provided at its lower end with a resilient biasing means (62) for maintaining the central rod (3) in a tendency to move in the direction of the movable filter element (41).

6. The pre-filter with double filter screens as in claim 5, wherein the elastic jacking mechanism (62) comprises a movable base (621) arranged at the lower end of the central rod (3), the movable base (621) is provided with a sewage drainage hole (6211) communicated with the sewage outlet (13), and a jacking spring (622) is arranged between the lower ends of the movable bases (621).

7. The double screen prefilter of claim 1 wherein said main screen (211) is located circumferentially inside said core (2) and said core (2) is provided circumferentially outside with flushing baffle means (23).

8. The double-filter-screen prefilter of claim 7 wherein said flushing guide mechanism (23) comprises a flushing frame body (24) which is sleeved on the circumferential outer side of said filter element body (2), a flushing guide cavity (25) which is communicated with said auxiliary filter cavity (22) is formed between the upper end of said flushing frame body (24) and the upper end of said filter element body (2), said flushing guide cavity (25) is communicated with said flushing guide assembly (7) which is located on the circumferential periphery of said main filter screen (211).

9. The dual screen prefilter of claim 8 wherein two correspondingly disposed arcuate gaps (241) are formed between the inner circumferential side of the upper end of the washing frame body (24) and the outer circumferential side of the upper end of the filter element body (2), and the upper and lower ends of the arcuate gaps (241) are respectively closed by sealing rings (242) to form said washing baffle cavity (25).

10. The dual-filter-screen prefilter of claim 9, wherein the flushing guide assembly (7) comprises a plurality of flushing frame support bars (71) vertically formed on the circumferential outer side of the flushing frame body (24), the flushing frame support bars (71) are provided with vertically arranged flushing grooves (72), the outer sides of the flushing grooves (72) are detachably provided with sealing bars (74) capable of sealing the flushing grooves (72) to form flushing channels (73) communicated with the flushing guide cavities (25), the upper ends of the flushing channels (73) extend to arc-shaped guide parts (75) on the circumferential inner side of the upper ends of the flushing frame body (24), one sides of the flushing frame support bars (71) far away from the sealing bars (74) are respectively provided with a plurality of flushing holes (76) vertically extending and communicated with the flushing channels (73), and the flushing holes (76) are respectively perpendicular to the main filter screens (211).

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