CN210057540U

CN210057540U - Back-flushing pre-filter

Info

Publication number: CN210057540U
Application number: CN201920716605.9U
Authority: CN
Inventors: 吕仁木
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-05-17
Filing date: 2019-05-17
Publication date: 2020-02-14
Anticipated expiration: 2029-05-17

Abstract

The utility model provides a leading filter of back flush belongs to filter technical field. It has solved the problem of how to further improve the washing effect of filter core. The backwash pre-filter comprises a switching head which can rotate and is arranged in the upper end of a body, the upper end of the switching head extends out of the body, a gap which communicates a water inlet with a water passing cavity is formed between the switching head and the body, the lower end of the switching head is located in a filter element, a water inlet hole is formed in the lower end face of the switching head and located above a cleaning rod, and a water outlet hole which can communicate the water inlet with the water inlet or the water outlet when the switching head rotates is formed in the side portion of the switching head. The backwashing pre-filter well improves the flushing effect of the filter element.

Description

Back-flushing pre-filter

Technical Field

The utility model belongs to the technical field of the filter, a filter is related to, especially, relate to a leading filter of back flush.

Background

At present, people have higher requirements on daily water and diet health, and more people adopt a pre-filter to purify water for one time so as to filter magazines and the like in a pipe network. The working principle of the pre-filter is generally as follows: tap water is connected into the shell of the pre-filter from the water inlet, and flows out from the water outlet after being filtered by the filter element in the shell for users to use. This is the normal working condition of the prefilter, however, after a period of use, many impurities and gels remain on the filter element, and the impurities and gels are generally difficult to clean. For this reason, chinese patent application No. 201520252203.X discloses a prefilter, which is convenient for users to clean impurities by arranging a siphon-type flushing device, but the siphon-type flushing device needs manual operation, so that jelly adhered to a filter element is difficult to clean.

In order to solve the above problems, the applicant has proposed a backwash filter with application number 201710360090.9, which comprises a body, wherein the body is provided with a water inlet, a water outlet and a drain outlet capable of being opened and closed, a cylindrical filter element is arranged in the body, the water inlet and the water outlet of the body are communicated through the filter element, a cleaning rod with an inner cavity is arranged in the filter element, a sewage suction port communicated with the inner cavity of the cleaning rod is arranged on the side part of the cleaning rod, the bottom of the filter element is provided with a sewage removal port communicated with the drain outlet, the lower end of the cleaning rod is opened and is opposite to the sewage removal port, the outer side of the cleaning rod is provided with a stress part, an impeller is arranged in the cleaning rod, and a supporting structure capable of supporting the cleaning rod to rotate when water flows through the. This back flush filter passes through impeller and bearing structure's cooperation messenger and washs the stick and can form quick rotation automatically when washing to in rotating the in-process and can being inhaled the washing stick smoothly by impurity and the jelly that the atress portion will be attached to on the filter core with soil pick-up mouth combined action, improved the washing effect of filter core well.

However, in practical applications, it is found that although the washing effect is not improved much compared with the filter which needs to be washed manually, the washing rod can only suck impurities and jelly from outside to inside due to the structural limitation, and cannot achieve the true back washing, so the washing effect is still not very ideal.

Disclosure of Invention

The utility model aims at the above-mentioned problem that prior art exists, provide a back flush leading filter, the technical problem that solve is how to further improve the washing effect of filter core.

The purpose of the utility model can be realized by the following technical proposal:

a back-flushing prefilter is composed of a main body with water inlet and outlet at its top and sewage draining hole at its bottom, a water passing cavity communicated with said sewage draining hole, a cylindrical filter core with hollow cleaning rod in it, an impeller linked to said cleaning rod, a supporting structure between said cleaning rod and filter core for supporting said cleaning rod to rotate when water flows through said impeller, and several water nozzles radially arranged on said cleaning rod and axially distributed along said cleaning rod. The water inlet is positioned above the cleaning rod, and the side part of the switching head is provided with a water outlet which can enable the water inlet to be communicated with the water inlet or the water outlet when the switching head rotates.

When normal water is discharged, the sewage draining hole is closed, the switching head is rotated to enable the water outlet hole to communicate the water inlet hole with the water outlet of the body, and at the moment, water is fed from the water inlet of the body and flows downwards into the water passing cavity through the gap between the body and the switching head. Because the sewage draining hole is closed, water can only flow into the filter element, and thus the water can be filtered and flows into the water inlet hole from bottom to top in the filter element, and then is supplied outwards through the water outlet hole and the water outlet hole in sequence.

When the filter element needs to be washed, the sewage draining hole is opened, the switching head is rotated to enable the water outlet hole to communicate with the water inlet of the water inlet hole and the body, at the moment, water is fed from the water supply port of the body and sequentially enters the cleaning rod through the water outlet hole and the water inlet hole, the cleaning rod generates quick rotation under the action of the impeller and the supporting structure, the water flowing into the cleaning rod is sprayed outwards from the water spraying port on the outer side of the cleaning rod to flush impurities and jelly attached to the filter element, and finally, sewage flows into the sewage draining hole from the water passing cavity to be discharged.

The filter element is reversely washed by the switching head, and the filter element is comprehensively washed from inside to outside by matching with the use of the cleaning rod, so that the backwashing is really realized, and the water pressure of the water sprayed out is very large due to the fact that the flow cross section area of the water spraying opening is smaller relative to the inner cavity of the cleaning rod, so that the washing effect is very obvious.

In the backwash pre-filter, the filter element comprises a cylindrical support and a cylindrical filter screen fixed outside the cylindrical support, a plurality of water passing holes distributed along the axial direction and the circumferential direction are arranged on the side part of the cylindrical support in a penetrating manner, an annular convex shoulder is arranged on the inner side of the upper end of the cylindrical support, an annular convex part is arranged on the outer side of the upper end of the cleaning rod, and the annular convex part is positioned on the inner side of the annular convex shoulder and forms clearance fit with the annular convex shoulder when the filter is.

During back washing, water can be sprayed in an all-directional mode only by matching with the rotation of the upper cleaning rod and the water spraying port on the cleaning rod, the water is required to flow into the cleaning rod as much as possible, the cleaning rod and the filter element are in an ideal state at the moment, however, a sealing ring cannot be arranged between the cleaning rod and the filter element due to the fact that the cleaning rod needs to rotate fast, and if the sealing ring is arranged, friction force is inevitably generated to block the rotation of the cleaning rod. Therefore, the inner side of the upper end of the cylindrical support of the filter element is provided with the annular convex shoulder, the outer side of the upper end of the cleaning rod is provided with the annular convex part, and the annular convex part is positioned at the inner side of the annular convex shoulder during back flushing and forms clearance fit with the annular convex shoulder, so that the water flow directly flowing into the filter element can be reduced to the minimum, and more water can flow into the cleaning rod to achieve the best flushing effect.

In the backwash pre-filter, the lower end surface of the switching head is provided with a stop block, the upper end surface of the annular convex part is provided with a plurality of convex blocks along the circumferential direction, and the side part of one of the convex blocks can be abutted against the side part of the stop block when the filter normally discharges water.

When the filter normally goes out water, water flows from bottom to top after entering the filter core, and the cleaning rod floats upwards, so that the stop block is arranged on the lower end face of the switching head, the upper end face of the annular convex part is provided with a plurality of convex blocks along the circumferential direction, and the unnecessary rotation of the cleaning rod is prevented by the fact that the side part of one of the convex blocks abuts against the side part of the stop block after the cleaning rod floats upwards, so that the stability of the filter in normal water outlet is improved.

In the backwash pre-filter, a sealing sleeve is arranged in the water outlet hole, a spring is arranged between the sealing sleeve and the inner wall of the water inlet hole, and one end face of the sealing sleeve is always abutted against the inner wall of the body under the elastic force of the spring.

Set up sealed sleeve in the apopore and be used for preventing water leakage, simultaneously because sealed sleeve terminal surface supports to lean on body inner wall to carry out synchronous pivoted when the switching head rotates, consequently utilize the elasticity of spring to compensate sealed sleeve's wearing and tearing, ensure that sealed sleeve's terminal surface can offset with body inner wall all the time and lean on and form effectual sealedly.

In the backwash pre-filter, the body comprises a shell and a top cover in threaded connection with the upper end of the shell, the water inlet and the water outlet are located on the top cover, the switching head is located in the top cover, the upper end of the switching head extends out of the top cover and is connected with the hand wheel, two limiting blocks are arranged on the upper end face of the top cover, limiting pieces are fixedly connected to the inner side of the hand wheel, the limiting pieces abut against the side portions of one limiting block when the filter normally produces water, and the limiting pieces abut against the side portions of the other limiting block when the filter backflush.

Two limit blocks are arranged on the upper end face of the top cover, the upper end of the switching head extends out of the top cover and is connected with a hand wheel, the inner side of the hand wheel is fixedly connected with a limit sheet, and the control of the rotation angle of the switching head is realized through the matching of the limit sheet and the two limit blocks when the switching head is rotated.

In the backwashing prefilter, the inner side of the lower end of the shell is fixedly connected with a plurality of convex ribs along the circumferential direction, the inner side of each convex rib is provided with a right-angle notch, the lower end of the cylindrical support is abutted against the right-angle notch of each convex rib, the upper end of the cylindrical support is circumferentially fixed with the switching head, the lower end of the shell is provided with a positioning hole in a penetrating manner along the axial direction, a positioning sleeve is fixed in the positioning hole, a sewage discharge head is connected in the positioning sleeve in a threaded manner, the lower end face of the cylindrical support is provided with a connecting hole, the upper end of the sewage discharge head is provided with a connecting part, the connecting part is slidably arranged in the connecting hole and circumferentially fixed with the cylindrical support, the sewage discharge hole is arranged on the sewage discharge head along the axial direction, the side part of the sewage discharge head is circumferentially provided with a plurality of through holes communicated with the sewage.

When water is discharged normally, the annular sealing part is positioned in the positioning sleeve to form sealing, the through hole is positioned in the positioning sleeve, and water flowing into the shell cannot flow into the sewage discharge hole. When the switching head is rotated to a back flushing state, the cylindrical support rotates along with the switching head, and as the connecting part on the sewage discharging head is arranged in the connecting hole in a sliding mode and is circumferentially fixed with the cylindrical support, and meanwhile, the sewage discharging head is in threaded connection with the positioning head and the positioning head is fixed in the positioning hole, the sewage discharging head can synchronously rotate along with the cylindrical support and move upwards along with the threads, so that the annular sealing part is moved upwards to the outside of the positioning sleeve, the through hole is opened, and sewage can flow into the sewage discharging hole through the through hole.

In the backwash pre-filter, the connecting holes are square holes, the shape of the connecting parts is the same as that of the connecting holes, and the opening depth of the connecting holes is larger than the length of the connecting parts.

The coupling hole is a square hole, and the shape of the coupling portion is the same as that of the coupling hole, so that the coupling portion and the cylindrical stent are circumferentially fixed by the non-circular fit. At the same time, the opening depth of the connecting hole is set to be larger than the length of the connecting part, so that the connecting part can axially move to a certain extent relative to the cylindrical support.

In foretell back flush leading filter, the switching head outside has linked firmly a plurality of cards along circumference, and each card all sets up along vertical direction, and the draw-in groove the same with card quantity is seted up along circumference to the up end of cylindric support, and each card lower extreme inserts in the draw-in groove that corresponds.

The switching head outside links firmly a plurality of cards along circumference, and the draw-in groove the same with card quantity is seted up along circumference to the up end of cylindric support, inserts through each card lower extreme and makes filter core and switching head can form circumference fixed in the draw-in groove that corresponds to can drive cylindric support when the switching head rotates and realize reciprocating of blowdown head.

In the backwash pre-filter, the outer side of the upper end of the positioning sleeve is provided with an annular retaining shoulder, the lower end face of the annular retaining shoulder abuts against the surface where the upper end opening of the positioning hole is located, the lower end of the positioning sleeve extends out of the lower end of the shell and is in threaded connection with the connecting pipe, and the connecting pipe abuts against the surface where the lower end opening of the positioning hole is located.

The lower end face of the annular shoulder is pressed on the face where the upper end opening of the positioning hole is located after the connecting pipe is screwed tightly, so that the connecting pipe, the positioning sleeve and the shell are fixed together, the positioning sleeve can be kept still when the switching head drives the sewage discharging head to rotate, and the sewage discharging head can move upwards or downwards along the thread to open or close the sewage discharging hole.

Compared with the prior art, the back flush prepositive filter changes the flushing direction of the filter element through the arrangement of the switching head, and simultaneously cooperates with the use of the upper cleaning rod to form the all-around flushing of the filter element from inside to outside, thereby really realizing the back flush, and because the flow cross section area of the water spray opening is reduced relative to the inner cavity of the cleaning rod, the water pressure of the water spray opening is very large, thereby well improving the flushing effect.

In addition, the sewage discharge head is circumferentially fixed with the cylindrical support, and the connecting part at the upper end of the sewage discharge head is arranged in the connecting hole in a sliding manner, so that the sewage discharge hole can be simultaneously closed or opened when the rotary switching head is used for switching between normal water outlet and backwashing, and the operation convenience of a user is improved.

Drawings

Fig. 1 is a longitudinal sectional view of the backwash pre-filter in normal water discharge.

Fig. 2 is a longitudinal sectional view of the backwash pre-filter in another direction when water is normally discharged.

Fig. 3 is an enlarged view at a in fig. 1.

Fig. 4 is an enlarged view at B in fig. 1.

FIG. 5 is a transverse cross-sectional view at the top cover of the present backflush prefilter.

Fig. 6 is a schematic view between the top cover and the handwheel in the backwash pre-filter.

Fig. 7 is another angle schematic diagram between the top cover and the handwheel in the backwash pre-filter.

FIG. 8 is a schematic view of the connection of the switch head to the cylindrical support in the present backwash pre-filter.

FIG. 9 is an exploded view of the present backwash pre-filter between the switch head, cylindrical support and wash rod.

FIG. 10 is another exploded perspective view of the present backwash pre-filter between the switch head, cylindrical support and wash rod.

Fig. 11 is a longitudinal sectional view of the present backwash pre-filter during backwash.

In the figure, 1, a body; 1a, a shell; 1a1, a water passing cavity; 1a2, convex ribs; 1b, a top cover; 1b1, water inlet; 1b2, a water outlet; 1b3 and a limiting block; 1c, a positioning sleeve; 1c1, annular shoulder; 1d, a sewage discharge head; 1d1, a sewage hole; 1d2, a coupling part; 1d3, vias; 1d4, annular seal; 2. a filter element; 2a, a cylindrical bracket; 2a1, annular shoulder; 2a2, coupling holes; 2a3, card slot; 2b, a cylindrical filter screen; 3. cleaning the rod; 3a, a water spraying opening; 3b, an annular convex part; 3b1, bumps; 4. an impeller; 5. switching the head; 5a, a water inlet hole; 5b, water outlet holes; 5c, a stop block; 5d, clamping the card; 6. a sealing sleeve; 7. a spring; 8. a hand wheel; 8a, a limiting sheet; 9. taking over a pipe; 10. a gap.

Detailed Description

The following are specific embodiments of the present invention and the accompanying drawings are used to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

As shown in fig. 1 and 11, the backwash pre-filter comprises a body 1, wherein the outer side of the upper end of the body 1 is provided with a water inlet 1b1 and a water outlet 1b2, the lower end of the body 1 is provided with a sewage discharge hole 1d1 which can be opened and closed, the body 1 is internally provided with a water passing cavity 1a1, and the sewage discharge hole 1d1, the water inlet 1b1 and the water outlet 1b2 are respectively communicated with the water passing cavity 1a 1. Specifically, the body 1 comprises a casing 1a with an open upper end and a top cover 1b screwed to the upper end of the casing 1a, the water passing cavity 1a1 is located in the casing 1a, and the water inlet 1b1 and the water outlet 1b2 are both located on the top cover 1 b.

As shown in fig. 1, 2, 9, 10 and 11, a cylindrical filter element 2 is arranged in the water passing cavity 1a1, the filter element 2 includes a cylindrical support 2a with an open upper end and a cylindrical filter screen 2b fixed outside the cylindrical support 2a, and a plurality of water passing holes distributed along the axial direction and the circumferential direction are arranged on the side portion of the cylindrical support 2a in a penetrating manner. Be equipped with hollow washing rod 3 in the

cylindric support

2a, 3 upper end openings of washing rod and 3 upper end inboards of washing rod have linked firmly

impeller

4, and 3 lower extremes of washing rod are sealed, and the lower extreme of cylindric support 2a seals, is equipped with between 3 lower terminal surfaces of washing rod and the filter core 2 and can support washing rod 3 when rivers pass through impeller 4 and carry out pivoted bearing structure, and 3 outsides of washing rod run through along the axial and are provided with a plurality of water jet 3 a. The specific construction of the filter element 2, the cleaning rod 3 and the support structure can be referred to a backflush filter of application No. 201710360090.9.

As shown in fig. 1, 2, 5, 8, 9 and 10, a columnar rotatable switching head 5 is provided in the top cover 1b, and a gap 10 communicating the water inlet 1b1 and the water passing chamber 1a1 is formed between the switching head 5 and the top cover 1 b. The switching head 5 lower extreme stretches into in the cylindric support 2a upper end and both form circumference fixed, specifically does, has linked firmly a plurality of cards 5d along circumference in the switching head 5 outside, and each card 5d all sets up along vertical direction, and the draw-in groove 2a3 the same with card 5d quantity is seted up along circumference to the up end of cylindric support 2a, and each card 5d lower extreme all inserts in the draw-in groove 2a3 that corresponds.

As shown in fig. 1 and 11, the lower end surface of the switch head 5 is provided with a water inlet hole 5a, the water inlet hole 5a is positioned above the cleaning rod 3, and the side portion of the switch head 5 is provided with a water outlet hole 5b which can enable the water inlet hole 5a to be communicated with the water inlet 1b1 or the water outlet 1b2 when the switch head 5 rotates. In this embodiment, be equipped with sealing sleeve 6 in apopore 5b, be equipped with spring 7 between sealing sleeve 6 and the 5a inner walls of inlet opening, spring 7 both ends push up respectively on 5a inner walls of inlet opening and sealing

sleeve

6, and 6 terminal surfaces of sealing sleeve are leaned on with top cap 1b inside wall all the time under spring 7's elastic force effect.

As shown in fig. 3, 9 and 10, the cylindrical support 2a is provided with an annular shoulder 2a1 on the inner side of the upper end thereof, and the cleaning rod 3 is provided with an annular protrusion 3b on the outer side of the upper end thereof, wherein the annular protrusion 3b is located in the annular shoulder 2a1 with a clearance fit when the water outlet 5b communicates the water inlet 5a with the water inlet 1b 1. The lower end face of the switching head 5 is provided with a stop block 5c, the upper end face of the annular convex part 3b is provided with a plurality of bumps 3b1 along the circumferential direction, and when the water outlet 5b communicates the water inlet 5a with the water outlet 1b2, the side part of one bump 3b1 can abut against the side part of the stop block 5 c.

As shown in fig. 6 and 7, the upper end of the switching head 5 extends out of the top cover 1b and is connected with a hand wheel 8, the inner side of the hand wheel 8 is fixedly connected with a limiting piece 8a, the upper end surface of the top cover 1b is provided with two limiting blocks 1b3, when the switching head 5 rotates to the water outlet 5b to communicate the water inlet 5a with the water outlet 1b2, the limiting piece 8a abuts against the side part of one limiting block 1b3, and when the switching head 5 rotates to the water outlet 5b to communicate the water inlet 5a with the water inlet 1b1, the limiting piece 8a abuts against the side part of the other limiting block 1b 3. When the switching head 5 is rotated, the rotation angle of the switching head 5 is controlled by the matching of the limiting piece 8a and the two limiting blocks 1b 3.

As shown in fig. 1, 2 and 4, the inner side of the lower end of the casing 1a is fixedly connected with a plurality of ribs 1a2 along the circumferential direction, the inner side of each rib 1a2 is provided with a right-angle notch, and the lower end of the cylindrical support 2a abuts against one side wall of the right-angle notch of each rib 1a 2. The lower end of the shell 1a is provided with a positioning hole in an axial penetrating manner, a positioning sleeve 1c is fixed in the positioning hole, a columnar pollution discharge head 1d is connected with the positioning sleeve 1c in a threaded manner, a connecting hole 2a2 is formed in the lower end face of the cylindrical support 2a, a connecting part 1d2 is formed in the upper end of the pollution discharge head 1d, a connecting part 1d2 is arranged in the connecting hole 2a2 in a sliding manner, the connecting part 1d2 is circumferentially fixed with the cylindrical support 2a, a pollution discharge hole 1d1 is formed in the pollution discharge head 1d in the axial direction, and a plurality of through holes 1d3 communicated with the pollution discharge hole 1d1 are circumferentially arranged on the side part of the. The outer side of the upper end of the sewage discharge head 1d is provided with an annular sealing part 1d4, the through hole 1d3 is positioned below the annular sealing part 1d4, and when the water outlet hole 5b communicates the water inlet hole 5a with the water outlet hole 1b2, the annular sealing part 1d4 is positioned in the positioning sleeve 1c to form sealing.

As shown in fig. 4, specifically, the outer side of the upper end of the positioning sleeve 1c is provided with an annular shoulder 1c1, the lower end surface of the annular shoulder 1c1 abuts against the surface of the upper port of the positioning hole, the lower end of the positioning sleeve 1c extends out of the lower end of the outer shell 1a and is in threaded connection with the adapter tube 9, the adapter tube 9 abuts against the surface of the lower port of the positioning hole, and when the adapter tube 9 is screwed, the annular shoulder 1c1 is pressed against the surface of the upper port of the positioning hole, so that the adapter tube 9, the positioning sleeve 1c and the outer shell 1a are fixed together. The connecting hole 2a2 is a square hole, the shape of the connecting part 1d2 is the same as that of the connecting hole 2a2, and the opening depth of the connecting hole 2a2 is larger than the length of the connecting part 1d 2.

As shown in fig. 1, during normal water discharge, the switching head 5 is rotated to make the water outlet hole 5b communicate the water inlet hole 5a with the water outlet hole 1b2, and at this time, the annular sealing part 1d4 is located in the positioning sleeve 1c to form a seal, so that the sewage discharge hole 1d1 is closed. Water is supplied from the water inlet 1b1 and flows down into the water passing chamber 1a1 through the gap 10 between the switch head 5 and the top cover 1b, and since the sewage discharge hole 1d1 is closed, water can only flow into the filter element 2, so that water is filtered by the filter element 2. At the same time, wash rod 3 floats upward by the buoyancy of the water so that one of the projections 3b1 side abuts against the stopper 5c side so that wash rod 3 does not rotate, and annular projection 3b is offset in height from annular shoulder 2a 1. The water filtered by the filter element 2 flows upward from the gap 10 between the filter element 2 and the cleaning rod 3 and flows into the cleaning rod 3 from bottom to top, and finally the water filtered by the filter element 2 flows into the water inlet 5a and is supplied to the outside through the water outlet 5b and the water outlet 1b2 in sequence.

As shown in fig. 11, during back flushing, the switching head 5 is rotated to make the water outlet hole 5b communicate the water inlet hole 5a with the water inlet 1b1, the switching head 5 drives the cylindrical support 2a and the pollution discharge head 1d to rotate synchronously, because the pollution discharge head 1d is connected with the positioning sleeve 1c by screw threads and the connecting part 1d2 on the pollution discharge head 1d is arranged in the connecting hole 2a2 in a sliding manner, the pollution discharge head 1d moves upwards along the screw threads to move the annular sealing part 1d4 upwards out of the positioning sleeve 1c, and the through hole 1d3 is opened. Water is supplied from a water supply port of the body 1 and enters the cleaning rod 3 through the water outlet hole 5b and the water inlet hole 5a in sequence, the cleaning rod 3 moves downwards under the impact of water flow and self gravity, the cleaning rod 3 generates rapid rotation under the action of the impeller 4 and the supporting structure, simultaneously, the water flowing into the cleaning rod 3 is sprayed outwards from the water spray port 3a outside the cleaning rod 3 to wash down impurities and jelly attached on the filter element 2, and finally, sewage flows into the sewage discharge hole 1d1 from the water passing cavity 1a1 through the through hole 1d3 and is discharged outwards.

The back-flushing prefilter changes the reverse direction of the flushing of the filter element 2 through the arrangement of the switching head 5, and simultaneously, the use of the upper cleaning rod 3 is matched, so that the filter element 2 is flushed from inside to outside in all directions, the back flushing is really realized, and the water pressure of the sprayed water is very high because the flow cross section area of the water spraying opening 3a is smaller than that of the inner cavity of the cleaning rod 3, so that the flushing effect is very obvious.

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

Claims

1. A back-washing pre-filter comprises a body (1) with a water inlet (1b1) and a water outlet (1b2) at the outer side of the upper end, a blow-off hole (1d1) capable of being opened and closed is arranged at the lower end of the body (1), a water passing cavity (1a1) communicated with the blow-off hole (1d1) is arranged in the body (1), a cylindrical filter element (2) is arranged in the water passing cavity (1a1), a hollow cleaning rod (3) is arranged in the filter element (2), an impeller (4) is fixedly connected with the upper end opening of the cleaning rod (3) and the inner side of the cleaning rod (3), a supporting structure capable of supporting the cleaning rod (3) to rotate when water flows through the impeller (4) is arranged between the lower end face of the cleaning rod (3) and the filter element (2), a plurality of water spray ports (3a) are radially arranged on the outer side of the cleaning rod (3) in a penetrating manner, and the water spray ports (3, be equipped with in the upper end of body (1) and can pivoted switching head (5), switching head (5) upper end stretches out outside body (1), have between switching head (5) and body (1) and be linked together clearance (10) with water inlet (1b1) and water passing cavity (1a1), switching head (5) lower extreme is located filter core (2), switching head (5) lower terminal surface is equipped with inlet opening (5a), inlet opening (5a) are located the top of wasing stick (3), switching head (5) lateral part is equipped with apopore (5b) that can make inlet opening (5a) and water inlet (1b1) or delivery port (1b2) be linked together when switching head (5) rotate.

2. The backwashing prefilter of claim 1 wherein said filter element (2) comprises a cylindrical support (2a) and a cylindrical filter screen (2b) fixed outside the cylindrical support (2a), the side of the cylindrical support (2a) is provided with a plurality of water passing holes distributed axially and circumferentially, the upper end of the cylindrical support (2a) is provided with an annular shoulder (2a1), the upper end of said cleaning rod (3) is provided with an annular protrusion (3b), and the annular protrusion (3b) is located inside the annular shoulder (2a1) and forms a clearance fit when the filter is backwashed.

3. The backwash pre-filter as claimed in claim 2, wherein the lower end surface of the switching head (5) is provided with a stopper (5c), the upper end surface of the annular convex part (3b) is provided with a plurality of projections (3b1) along the circumferential direction, and the side of one projection (3b1) can abut against the side of the stopper (5c) when the filter normally discharges water.

4. The pre-filter of claim 2 or 3, characterized in that a sealing sleeve (6) is arranged in the water outlet (5b), a spring (7) is arranged between the sealing sleeve (6) and the inner wall of the water inlet (5a), and one end face of the sealing sleeve (6) is always abutted against the inner wall of the body (1) under the elastic force of the spring (7).

5. The backwash pre-filter according to claim 4, wherein the body (1) comprises a shell (1a) and a top cover (1b) which is connected with the upper end of the shell (1a) in a threaded manner, the water inlet (1b1) and the water outlet (1b2) are arranged on the top cover (1b), the switching head (5) is arranged in the top cover (1b), the upper end of the switching head (5) extends out of the top cover (1b) and is connected with a hand wheel (8), the upper end face of the top cover (1b) is provided with two limiting blocks (1b3), the inner side of the hand wheel (8) is fixedly connected with a limiting piece (8a), the limiting piece (8a) abuts against the side of one limiting block (1b3) when the filter normally outputs water, and the limiting piece (8a) abuts against the side of the other limiting block (1b3) when the filter backflushes.

6. The backwashing prefilter of claim 5 wherein the inner side of the lower end of said housing (1a) is fixedly connected with a plurality of ribs (1a2) along the circumferential direction, each rib (1a2) is provided with a right-angle notch at the inner side, the lower end of said cylindrical support (2a) is abutted against the right-angle notch of each rib (1a2), the upper end of said cylindrical support (2a) is circumferentially fixed with said switching head (5), the lower end of said housing (1a) is provided with a positioning hole along the axial direction, a positioning sleeve (1c) is fixed in said positioning hole, said positioning sleeve (1c) is connected with said pollution discharge head (1d) by internal thread, the lower end face of said cylindrical support (2a) is provided with a connecting hole (2a2), the upper end of said pollution discharge head (1d2), said connecting portion (1d2) is slidably arranged in said connecting hole (2a2), and said connecting portion (1d2) is circumferentially fixed with said cylindrical support (2a), the blowdown hole (1d1) are opened on blowdown head (1d) along the axial, the lateral part of blowdown head (1d) is provided with a plurality of through-holes (1d3) that are linked together with blowdown hole (1d1) along circumference run-through, the blowdown head (1d) upper end outside is equipped with annular sealing portion (1d4), through-hole (1d3) are located the below of annular sealing portion (1d4), annular sealing portion (1d4) are located position sleeve (1c) and form sealedly when normally going out water.

7. The backwash pre-filter according to claim 6, wherein the coupling holes (2a2) are square holes, the shape of the coupling part (1d2) is the same as that of the coupling holes (2a2), and the opening depth of the coupling holes (2a2) is larger than the length of the coupling part (1d 2).

8. The backwash prefilter according to claim 6, wherein a plurality of clamping pieces (5d) are fixed to the outer side of said switching head (5) along the circumferential direction, each clamping piece (5d) is arranged along the vertical direction, the upper end surface of said cylindrical support (2a) is circumferentially provided with a number of clamping slots (2a3) equal to the number of clamping pieces (5d), and the lower end of each clamping piece (5d) is inserted into the corresponding clamping slot (2a 3).

9. The backwash pre-filter as claimed in claim 6, wherein the locating sleeve (1c) is provided with an annular retaining shoulder (1c1) at the upper end outside, the lower end face of the annular retaining shoulder (1c1) abuts against the surface of the upper port of the locating hole, the lower end of the locating sleeve (1c) extends out of the lower end of the housing (1a) and is connected with a connecting pipe (9) in a threaded manner, and the connecting pipe (9) abuts against the surface of the lower port of the locating hole.